8544 files changed, 827894 insertions, 768819 deletions

diff --git a/.appveyor.yml b/.appveyor.yml
deleted file mode 100644
index 1ea5e59210..0000000000
--- a/.appveyor.yml
+++ /dev/null
@@ -1,135 +0,0 @@
----
-version: '{build}'
-init:
-  - git config --global user.name git
-  - git config --global user.email svn-admin@ruby-lang.org
-  - git config --global core.autocrlf false
-  - git config --global core.eol lf
-  - git config --global advice.detachedHead 0
-shallow_clone: true
-clone_depth: 10
-platform:
-  - x64
-skip_commits:
-  message: /\[DOC\]/
-  files:
-    - doc/*
-    - '**/*.md'
-    - '**/*.rdoc'
-    - '**/.document'
-environment:
-  ruby_version: "24-%Platform%"
-  zlib_version: "1.2.12"
-  matrix:
-    - build: vs
-      vs: 120
-      ssl: OpenSSL
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      GEMS_FOR_TEST: ""
-    - build: vs
-      vs: 140
-      ssl: OpenSSL-v111
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      GEMS_FOR_TEST: ""
-  RELINE_TEST_ENCODING: "UTF-8"
-cache:
-  - c:\Tools\vcpkg\installed\
-for:
--
-  matrix:
-    only:
-      - build: vs
-  install:
-    - ver
-    - chcp
-    - SET BITS=%Platform:x86=32%
-    - SET BITS=%BITS:x=%
-    - SET OPENSSL_DIR=C:\%ssl%-Win%BITS%
-    - cd C:\Tools\vcpkg
-    - git pull -q
-    - .\bootstrap-vcpkg.bat
-    - cd %APPVEYOR_BUILD_FOLDER%
-    - vcpkg --triplet %Platform%-windows install libffi libyaml readline zlib
-    - CALL SET vcvars=%%^VS%VS%COMNTOOLS^%%..\..\VC\vcvarsall.bat
-    - SET vcvars
-    - '"%vcvars%" %Platform:x64=amd64%'
-    - SET ruby_path=C:\Ruby%ruby_version:-x86=%
-    - SET PATH=\usr\local\bin;%ruby_path%\bin;%PATH%;C:\msys64\mingw64\bin;C:\msys64\usr\bin
-    - ruby --version
-    - 'cl'
-    - echo> Makefile srcdir=.
-    - echo>> Makefile MSC_VER=0
-    - echo>> Makefile RT=none
-    - echo>> Makefile RT_VER=0
-    - echo>> Makefile BUILTIN_ENCOBJS=nul
-    - type win32\Makefile.sub >> Makefile
-    - nmake %mflags% up VCSUP="echo Update OK"
-    - nmake %mflags% extract-extlibs
-    - del Makefile
-    - mkdir \usr\local\bin
-    - mkdir \usr\local\include
-    - mkdir \usr\local\lib
-    - SET ZLIB_ZIP=.downloaded-cache\zlib%zlib_version:.=%.zip
-    - if not exist %ZLIB_ZIP% curl -fsSL -o %ZLIB_ZIP% --retry 10 https://zlib.net/zlib%zlib_version:.=%.zip
-    - 7z x -aos -o%APPVEYOR_BUILD_FOLDER%\ext\zlib %ZLIB_ZIP%
-    - for %%I in (%OPENSSL_DIR%\*.dll) do mklink /h \usr\local\bin\%%~nxI %%I
-    - for %%I in (c:\Tools\vcpkg\installed\%Platform%-windows\bin\*.dll) do (
-        if not %%~nI == readline mklink \usr\local\bin\%%~nxI %%I
-      )
-    - attrib +r /s /d
-    - mkdir %Platform%-mswin_%vs%
-  build_script:
-    - cd %APPVEYOR_BUILD_FOLDER%
-    - cd %Platform%-mswin_%vs%
-    - >-
-      ..\win32\configure.bat
-      --with-opt-dir="/usr/local;c:/Tools/vcpkg/installed/%Platform%-windows"
-      --with-openssl-dir=%OPENSSL_DIR:\=/%
-    - nmake -l
-    - nmake install-nodoc
-    - \usr\bin\ruby -v -e "p :locale => Encoding.find('locale'), :filesystem => Encoding.find('filesystem')"
-    - if not "%GEMS_FOR_TEST%" == "" \usr\bin\gem install --no-document %GEMS_FOR_TEST%
-    - \usr\bin\ruby -ropenssl -e "puts 'Build    ' + OpenSSL::OPENSSL_VERSION, 'Runtime  ' + OpenSSL::OPENSSL_LIBRARY_VERSION"
-  test_script:
-    - set /a JOBS=%NUMBER_OF_PROCESSORS%
-    - nmake -l "TESTOPTS=-v -q" btest
-    - nmake -l "TESTOPTS=-v -q" test-basic
-    - >-
-      nmake -l "TESTOPTS=-v --timeout-scale=3.0
-      --excludes=../test/excludes/_appveyor -j%JOBS%
-      --exclude win32ole
-      --exclude test_bignum
-      --exclude test_syntax
-      --exclude test_open-uri
-      --exclude test_bundled_ca
-      " test-all
-    # separately execute tests without -j which may crash worker with -j.
-    - >-
-      nmake -l
-      "TESTOPTS=-v --timeout-scale=3.0 --excludes=../test/excludes/_appveyor"
-      TESTS="
-      ../test/win32ole
-      ../test/ruby/test_bignum.rb
-      ../test/ruby/test_syntax.rb
-      ../test/open-uri/test_open-uri.rb
-      ../test/rubygems/test_bundled_ca.rb
-      " test-all
-    - nmake -l test-spec MSPECOPT=-fs # not using `-j` because sometimes `mspec -j` silently dies on Windows
-notifications:
-  - provider: Webhook
-    method: POST
-    url:
-      secure: CcFlJNDJ/a6to7u3Z4Fnz6dScEPNx7hTha2GkSRlV+1U6dqmxY/7uBcLXYb9gR3jfQk6w+2o/HrjNAyXMNGU/JOka3s2WRI4VKitzM+lQ08owvJIh0R7LxrGH0J2e81U # ruby-lang slack: ruby/simpler-alerts-bot
-    body: >-
-      {{^isPullRequest}}
-        {
-          "ci": "AppVeyor CI",
-          "env": "Visual Studio 2013 / 2015",
-          "url": "{{buildUrl}}",
-          "commit": "{{commitId}}",
-          "branch": "{{branch}}"
-        }
-      {{/isPullRequest}}
-    on_build_success: false
-    on_build_failure: true
-    on_build_status_changed: false
diff --git a/.cirrus.yml b/.cirrus.yml
deleted file mode 100644
index 1e7832ed00..0000000000
--- a/.cirrus.yml
+++ /dev/null
@@ -1,133 +0,0 @@
-# This CI is used to test Arm cases. We can set the maximum 16 tasks.
-# The entire testing design is inspired from .github/workflows/compilers.yml.
-
-# By default, Cirrus mounts an empty volume to `/tmp`
-# which triggers all sorts of warnings like "system temporary path is world-writable: /tmp".
-# Lets workaround it by specifying a custom volume mount point.
-env:
-  CIRRUS_VOLUME: /cirrus-ci-volume
-  LANG: C.UTF-8
-
-task:
-  name: Arm64 Graviton2 / $CC
-  skip: "changesIncludeOnly('doc/**', '**.{md,rdoc}', '.document')"
-  arm_container:
-    # We use the arm64 images at https://github.com/ruby/ruby-ci-image/pkgs/container/ruby-ci-image .
-    image: ghcr.io/ruby/ruby-ci-image:$CC
-    # Define the used cpu core in each matrix task. We can use total 16 cpu
-    # cores in entire matrix. [cpu] = [total cpu: 16] / [number of tasks]
-    cpu: 8
-    # We can request maximum 4 GB per cpu.
-    # [memory per task] = [memory per cpu: 4 GB] * [cpu]
-    memory: 32G
-  env:
-    CIRRUS_CLONE_DEPTH: 50
-    optflags: '-O1'
-    debugflags: '-ggdb3'
-    RUBY_PREFIX: /tmp/ruby-prefix
-    RUBY_DEBUG: ci rgengc
-    RUBY_TESTOPTS: >-
-      -q
-      --color=always
-      --tty=no
-    matrix:
-      CC: clang-12
-      CC: gcc-11
-  id_script: id
-  set_env_script:
-    # Set `GNUMAKEFLAGS`, because the flags are GNU make specific. Note using
-    # the `make` environment variable used in compilers.yml causes some rubygems
-    # tests to fail.
-    # https://github.com/rubygems/rubygems/issues/4921
-    - echo "GNUMAKEFLAGS=-s -j$((1 + $CIRRUS_CPU))" >> $CIRRUS_ENV
-  print_env_script:
-    - echo "GNUMAKEFLAGS=$GNUMAKEFLAGS"
-  # Arm containers are executed in AWS's EKS, and it's not yet supporting IPv6
-  # See https://github.com/aws/containers-roadmap/issues/835
-  disable_ipv6_script: sudo ./tool/disable_ipv6.sh
-  autogen_script: ./autogen.sh
-  configure_script: >-
-    ./configure -C
-    --enable-debug-env
-    --disable-install-doc
-    --with-ext=-test-/cxxanyargs,+
-    --prefix="$RUBY_PREFIX"
-  make_extract-extlibs_script: make extract-extlibs
-  make_incs_script: make incs
-  make_script: make
-  make_leaked-globals_script: make leaked-globals
-  make_test_script: make test
-  make_install_script: make install
-  install_gems_for_test_script: $RUBY_PREFIX/bin/gem install --no-doc timezone tzinfo
-  make_test-tool_script: make test-tool
-  make_test-all_script: make test-all
-  make_test-spec_script: make test-spec
-
-# The following is to test YJIT on ARM64 CPUs available on Cirrus CI
-yjit_task:
-  name: Arm64 Graviton2 / $CC YJIT
-  auto_cancellation: $CIRRUS_BRANCH != 'master'
-  skip: "changesIncludeOnly('doc/**', '**.{md,rdoc}')"
-  arm_container:
-    # We use the arm64 images at https://github.com/ruby/ruby-ci-image/pkgs/container/ruby-ci-image .
-    image: ghcr.io/ruby/ruby-ci-image:$CC
-    # Define the used cpu core in each matrix task. We can use total 16 cpu
-    # cores in entire matrix. [cpu] = [total cpu: 16] / [number of tasks]
-    cpu: 8
-    # We can request maximum 4 GB per cpu.
-    # [memory per task] = [memory per cpu: 4 GB] * [cpu]
-    memory: 32G
-  env:
-    CIRRUS_CLONE_DEPTH: 50
-    optflags: '-O1'
-    debugflags: '-ggdb3'
-    RUBY_PREFIX: /tmp/ruby-prefix
-    RUBY_DEBUG: ci rgengc
-    RUBY_TESTOPTS: >-
-      -q
-      --color=always
-      --tty=no
-    matrix:
-      - CC: clang-12
-        configure: --enable-yjit=dev
-      - CC: gcc-11
-        configure: --enable-yjit
-  id_script: id
-  set_env_script:
-    # Set `GNUMAKEFLAGS`, because the flags are GNU make specific. Note using
-    # the `make` environment variable used in compilers.yml causes some rubygems
-    # tests to fail.
-    # https://github.com/rubygems/rubygems/issues/4921
-    - echo "GNUMAKEFLAGS=-s -j$((1 + $CIRRUS_CPU))" >> $CIRRUS_ENV
-  print_env_script:
-    - echo "GNUMAKEFLAGS=$GNUMAKEFLAGS"
-  # Arm containers are executed in AWS's EKS, and it's not yet supporting IPv6
-  # See https://github.com/aws/containers-roadmap/issues/835
-  disable_ipv6_script: sudo ./tool/disable_ipv6.sh
-  install_rust_script:
-    - sudo apt-get update -y
-    - sudo apt-get install -y curl
-    - "curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y"
-  autogen_script: ./autogen.sh
-  configure_script: >-
-    source $HOME/.cargo/env && ./configure -C
-    --enable-debug-env
-    --disable-install-doc
-    --with-ext=-test-/cxxanyargs,+
-    --prefix="$RUBY_PREFIX"
-    $configure
-  make_miniruby_script: source $HOME/.cargo/env && make miniruby
-  make_bindgen_script: |
-    if [[ "$CC" = "clang-12" ]]; then
-      source $HOME/.cargo/env && make yjit-bindgen
-    else
-      echo "only running bindgen on clang image"
-    fi
-  boot_miniruby_script: RUST_BACKTRACE=1 ./miniruby --yjit-call-threshold=1 -e0
-  test_dump_insns_script: RUST_BACKTRACE=1 ./miniruby --yjit-call-threshold=1 --yjit-dump-insns -e0
-  output_stats_script: RUST_BACKTRACE=1 ./miniruby --yjit-call-threshold=1 --yjit-stats -e0
-  full_build_script: source $HOME/.cargo/env && make
-  cargo_test_script: source $HOME/.cargo/env && cd yjit && cargo test
-  make_test_script: source $HOME/.cargo/env && make test RUN_OPTS="--yjit-call-threshold=1 --yjit-verify-ctx"
-  make_test_all_script: source $HOME/.cargo/env && make test-all RUN_OPTS="--yjit-call-threshold=1" TESTOPTS="$RUBY_TESTOPTS"
-  make_test_spec_script: source $HOME/.cargo/env && make test-spec RUN_OPTS="--yjit-call-threshold=1"
diff --git a/.document b/.document
index ec2fa09326..82ca602bfb 100644
--- a/.document
+++ b/.document
@@ -15,18 +15,26 @@ array.rb
 ast.rb
 dir.rb
 gc.rb
+hash.rb
 io.rb
 kernel.rb
 marshal.rb
 numeric.rb
 nilclass.rb
 pack.rb
+pathname_builtin.rb
 ractor.rb
 string.rb
+symbol.rb
 timev.rb
 thread_sync.rb
 trace_point.rb
 warning.rb
+yjit.rb
+zjit.rb
+
+# Errno::*
+known_errors.inc
 
 # the lib/ directory (which has its own .document file)
 lib
@@ -45,7 +53,4 @@ COPYING.ja
 
 LEGAL
 
-# win32/README.win32 linked from README.md
-win32
-
 doc
diff --git a/.gdbinit b/.gdbinit
index 34d044caf6..bda544c641 100644
--- a/.gdbinit
+++ b/.gdbinit
@@ -1,23 +1,7 @@
-set startup-with-shell off
-
-define hook-run
-  set $color_type = 0
-  set $color_highlite = 0
-  set $color_end = 0
-end
-
 define ruby_gdb_init
-  if !$color_type
-    set $color_type = "\033[31m"
-  end
-  if !$color_highlite
-    set $color_highlite = "\033[36m"
-  end
-  if !$color_end
-    set $color_end = "\033[m"
-  end
-  if ruby_dummy_gdb_enums.special_consts
-  end
+  init-if-undefined $color_type = "\033[31m"
+  init-if-undefined $color_highlite = "\033[36m"
+  init-if-undefined $color_end = "\033[m"
 end
 
 # set prompt \033[36m(gdb)\033[m\040
@@ -67,7 +51,7 @@ define rp
     printf "%sT_OBJECT%s: ", $color_type, $color_end
     print ((struct RObject *)($arg0))->basic
     if ($flags & ROBJECT_EMBED)
-      print/x *((VALUE*)((struct RObject*)($arg0))->as.ary) @ (ROBJECT_EMBED_LEN_MAX+0)
+      print/x *((VALUE*)((struct RObject*)($arg0))->as.ary) @ (RSHAPE_CAPACITY(rb_obj_shape_id($arg0)))
     else
       print (((struct RObject *)($arg0))->as.heap)
       if (((struct RObject*)($arg0))->as.heap.numiv) > 0
@@ -99,13 +83,11 @@ define rp
     set $regsrc = ((struct RRegexp*)($arg0))->src
     set $rsflags = ((struct RBasic*)$regsrc)->flags
     printf "%sT_REGEXP%s: ", $color_type, $color_end
-    set $len = ($rsflags & RUBY_FL_USER1) ? \
-            ((struct RString*)$regsrc)->as.heap.len : \
-            (($rsflags & (RUBY_FL_USER2|RUBY_FL_USER3|RUBY_FL_USER4|RUBY_FL_USER5|RUBY_FL_USER6)) >> RUBY_FL_USHIFT+2)
+    set $len = ((struct RString*)($arg0))->len
     set print address off
     output *(char *)(($rsflags & RUBY_FL_USER1) ? \
-	    ((struct RString*)$regsrc)->as.heap.ptr : \
-	    ((struct RString*)$regsrc)->as.ary) @ $len
+            ((struct RString*)$regsrc)->as.heap.ptr : \
+            ((struct RString*)$regsrc)->as.embed.ary) @ $len
     set print address on
     printf " len:%ld ", $len
     if $flags & RUBY_FL_USER6
@@ -126,26 +108,26 @@ define rp
       printf "%sT_ARRAY%s: len=%ld ", $color_type, $color_end, $len
       printf "(embed) "
       if ($len == 0)
-	printf "{(empty)} "
+        printf "{(empty)} "
       else
-	print/x *((VALUE*)((struct RArray*)($arg0))->as.ary) @ $len
-	printf " "
+        print/x *((VALUE*)((struct RArray*)($arg0))->as.ary) @ $len
+        printf " "
       end
     else
       set $len = ((struct RArray*)($arg0))->as.heap.len
       printf "%sT_ARRAY%s: len=%ld ", $color_type, $color_end, $len
       if ($flags & RUBY_FL_USER2)
-	printf "(shared) shared="
-	output/x ((struct RArray*)($arg0))->as.heap.aux.shared_root
-	printf " "
+        printf "(shared) shared="
+        output/x ((struct RArray*)($arg0))->as.heap.aux.shared_root
+        printf " "
       else
-	printf "(ownership) capa=%ld ", ((struct RArray*)($arg0))->as.heap.aux.capa
+        printf "(ownership) capa=%ld ", ((struct RArray*)($arg0))->as.heap.aux.capa
       end
       if ($len == 0)
-	printf "{(empty)} "
+        printf "{(empty)} "
       else
-	print/x *((VALUE*)((struct RArray*)($arg0))->as.heap.ptr) @ $len
-	printf " "
+        print/x *((VALUE*)((struct RArray*)($arg0))->as.heap.ptr) @ $len
+        printf " "
       end
     end
     print (struct RArray *)($arg0)
@@ -157,13 +139,15 @@ define rp
   if ($flags & RUBY_T_MASK) == RUBY_T_HASH
     printf "%sT_HASH%s: ", $color_type, $color_end,
     if (((struct RHash *)($arg0))->basic.flags & RHASH_ST_TABLE_FLAG)
-      printf "st len=%ld ", ((struct RHash *)($arg0))->as.st->num_entries
+      set $st = (struct st_table *)((uintptr_t)($arg0) + sizeof(struct RHash))
+      printf "st len=%ld ", $st->num_entries
+      print $st
     else
       printf "li len=%ld bound=%ld ", \
         ((((struct RHash *)($arg0))->basic.flags & RHASH_AR_TABLE_SIZE_MASK) >> RHASH_AR_TABLE_SIZE_SHIFT), \
         ((((struct RHash *)($arg0))->basic.flags & RHASH_AR_TABLE_BOUND_MASK) >> RHASH_AR_TABLE_BOUND_SHIFT)
+	print (struct ar_table_struct *)((uintptr_t)($arg0) + sizeof(struct RHash))
     end
-    print (struct RHash *)($arg0)
   else
   if ($flags & RUBY_T_MASK) == RUBY_T_STRUCT
     set $len = (($flags & (RUBY_FL_USER1|RUBY_FL_USER2)) ? \
@@ -201,12 +185,19 @@ define rp
     print (struct RBasic *)($arg0)
   else
   if ($flags & RUBY_T_MASK) == RUBY_T_DATA
-    if ((struct RTypedData *)($arg0))->typed_flag == 1
-      printf "%sT_DATA%s(%s): ", $color_type, $color_end, ((struct RTypedData *)($arg0))->type->wrap_struct_name
-      print (struct RTypedData *)($arg0)
+    if ($flags & RUBY_TYPED_FL_IS_TYPED_DATA)
+      set $data = (struct RTypedData *)($arg0)
+      set $type = (const rb_data_type_t *)($data->type & ~1)
+      printf "%sT_DATA%s(%s): ", $color_type, $color_end, $type->wrap_struct_name
+      print *$type
+      if ($data->type & 1)
+        print (void *)&$data->data
+      else
+        print $data
+      end
     else
       printf "%sT_DATA%s: ", $color_type, $color_end
-      print (struct RData *)($arg0)
+      print *(struct RData *)($arg0)
     end
   else
   if ($flags & RUBY_T_MASK) == RUBY_T_MATCH
@@ -440,13 +431,11 @@ end
 
 define output_string
   set $flags = ((struct RBasic*)($arg0))->flags
-  set $len = ($flags & RUBY_FL_USER1) ? \
-          ((struct RString*)($arg0))->as.heap.len : \
-          (($flags & (RUBY_FL_USER2|RUBY_FL_USER3|RUBY_FL_USER4|RUBY_FL_USER5|RUBY_FL_USER6)) >> RUBY_FL_USHIFT+2)
+  set $len = ((struct RString*)($arg0))->len
   if $len > 0
     output *(char *)(($flags & RUBY_FL_USER1) ? \
-	    ((struct RString*)($arg0))->as.heap.ptr : \
-	    ((struct RString*)($arg0))->as.ary) @ $len
+            ((struct RString*)($arg0))->as.heap.ptr : \
+            ((struct RString*)($arg0))->as.embed.ary) @ $len
   else
     output ""
   end
@@ -454,13 +443,11 @@ end
 
 define print_string
   set $flags = ((struct RBasic*)($arg0))->flags
-  set $len = ($flags & RUBY_FL_USER1) ? \
-          ((struct RString*)($arg0))->as.heap.len : \
-          (($flags & (RUBY_FL_USER2|RUBY_FL_USER3|RUBY_FL_USER4|RUBY_FL_USER5|RUBY_FL_USER6)) >> RUBY_FL_USHIFT+2)
+  set $len = ((struct RString*)($arg0))->len
   if $len > 0
     printf "%s", *(char *)(($flags & RUBY_FL_USER1) ? \
-	    ((struct RString*)($arg0))->as.heap.ptr : \
-	    ((struct RString*)($arg0))->as.ary) @ $len
+            ((struct RString*)($arg0))->as.heap.ptr : \
+            ((struct RString*)($arg0))->as.embed.ary) @ $len
   end
 end
 
@@ -543,14 +530,14 @@ document rp_bignum
 end
 
 define rp_class
+  set $class_and_classext = (struct RClass_and_rb_classext_t *)($arg0)
   printf "(struct RClass *) %p", (void*)$arg0
-  if RCLASS_ORIGIN((struct RClass *)($arg0)) != $arg0
-    printf " -> %p", RCLASS_ORIGIN((struct RClass *)($arg0))
+  if $class_and_classext->classext->origin_ != (VALUE)$arg0
+    printf " -> %p", $class_and_classext->classext->origin_
   end
   printf "\n"
   rb_classname $arg0
-  print/x *(struct RClass *)($arg0)
-  print *RCLASS_EXT((struct RClass *)($arg0))
+  print/x *$class_and_classext
 end
 document rp_class
   Print the content of a Class/Module.
@@ -689,11 +676,6 @@ define nd_stts
 end
 
 
-define nd_entry
-  printf "%su3.entry%s: ", $color_highlite, $color_end
-  p ($arg0).u3.entry
-end
-
 define nd_vid
   printf "%su1.id%s: ", $color_highlite, $color_end
   p ($arg0).u1.id
@@ -868,22 +850,22 @@ define rb_numtable_entry
     set $rb_numtable_p = $rb_numtable_tbl->as.packed.bins
     while $rb_numtable_p && $rb_numtable_p < $rb_numtable_tbl->as.packed.bins+$rb_numtable_tbl->num_entries
       if $rb_numtable_p.k == $rb_numtable_id
-	set $rb_numtable_key = $rb_numtable_p.k
-	set $rb_numtable_rec = $rb_numtable_p.v
-	set $rb_numtable_p = 0
+        set $rb_numtable_key = $rb_numtable_p.k
+        set $rb_numtable_rec = $rb_numtable_p.v
+        set $rb_numtable_p = 0
       else
-	set $rb_numtable_p = $rb_numtable_p + 1
+        set $rb_numtable_p = $rb_numtable_p + 1
       end
     end
   else
     set $rb_numtable_p = $rb_numtable_tbl->as.big.bins[st_numhash($rb_numtable_id) % $rb_numtable_tbl->num_bins]
     while $rb_numtable_p
       if $rb_numtable_p->key == $rb_numtable_id
-	set $rb_numtable_key = $rb_numtable_p->key
-	set $rb_numtable_rec = $rb_numtable_p->record
-	set $rb_numtable_p = 0
+        set $rb_numtable_key = $rb_numtable_p->key
+        set $rb_numtable_rec = $rb_numtable_p->record
+        set $rb_numtable_p = 0
       else
-	set $rb_numtable_p = $rb_numtable_p->next
+        set $rb_numtable_p = $rb_numtable_p->next
       end
     end
   end
@@ -921,10 +903,10 @@ document rb_method_entry
 end
 
 define rb_classname
-  # up to 128bit int
-  set $rb_classname = rb_mod_name($arg0)
-  if $rb_classname != RUBY_Qnil
-    rp $rb_classname
+  set $rb_classname = ((struct RClass_and_rb_classext_t*)$arg0)->classext->classpath
+  if $rb_classname != RUBY_Qfalse
+    print_string $rb_classname
+    printf "\n"
   else
     echo anonymous class/module\n
   end
@@ -961,7 +943,7 @@ define iseq
       set $operand_size = ((INSN*)($arg0))->operand_size
       set $operands = ((INSN*)($arg0))->operands
       while $i < $operand_size
-	rp $operands[$i++]
+        rp $operands[$i++]
       end
     end
   end
@@ -1131,7 +1113,7 @@ define rb_ps_thread
   set $ps_thread = (struct RTypedData*)$arg0
   set $ps_thread_th = (rb_thread_t*)$ps_thread->data
   printf "* #<Thread:%p rb_thread_t:%p native_thread:%p>\n", \
-    $ps_thread, $ps_thread_th, $ps_thread_th->thread_id
+    $ps_thread, $ps_thread_th, $ps_thread_th->nt
   set $cfp = $ps_thread_th->ec->cfp
   set $cfpend = (rb_control_frame_t *)($ps_thread_th->ec->vm_stack + $ps_thread_th->ec->vm_stack_size)-1
   while $cfp < $cfpend
@@ -1279,9 +1261,9 @@ document rb_count_objects
   Counts all objects grouped by type.
 end
 
-# Details: https://bugs.ruby-lang.org/projects/ruby-master/wiki/MachineInstructionsTraceWithGDB
+# Details: https://github.com/ruby/ruby/wiki/Machine-Instructions-Trace-with-GDB
 define trace_machine_instructions
-  set logging on
+  set logging enabled
   set height 0
   set width 0
   display/i $pc
@@ -1316,13 +1298,12 @@ define dump_node
   set $flags = ((struct RBasic*)($str))->flags
   printf "%s", (char *)(($flags & RUBY_FL_USER1) ? \
                         ((struct RString*)$str)->as.heap.ptr : \
-                        ((struct RString*)$str)->as.ary)
+                        ((struct RString*)$str)->as.embed.ary)
 end
 
 define print_flags
   printf "RUBY_FL_WB_PROTECTED: %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_WB_PROTECTED ? "1" : "0"
-  printf "RUBY_FL_PROMOTED0   : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_PROMOTED0 ? "1" : "0"
-  printf "RUBY_FL_PROMOTED1   : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_PROMOTED1 ? "1" : "0"
+  printf "RUBY_FL_PROMOTED    : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_PROMOTED ? "1" : "0"
   printf "RUBY_FL_FINALIZE    : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_FINALIZE ? "1" : "0"
   printf "RUBY_FL_SHAREABLE   : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_SHAREABLE ? "1" : "0"
   printf "RUBY_FL_EXIVAR      : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_EXIVAR ? "1" : "0"
@@ -1348,3 +1329,8 @@ define print_flags
   printf "RUBY_FL_USER17      : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_USER17 ? "1" : "0"
   printf "RUBY_FL_USER18      : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_USER18 ? "1" : "0"
 end
+
+source -s misc/gdb.py
+
+# Moved from beginning, since it fails on older gdbs
+set startup-with-shell off
diff --git a/.git-blame-ignore-revs b/.git-blame-ignore-revs
index 6c5eac5a0f..d98646febf 100644
--- a/.git-blame-ignore-revs
+++ b/.git-blame-ignore-revs
@@ -5,6 +5,12 @@
 
 # Expand tabs
 5b21e94bebed90180d8ff63dad03b8b948361089
+c5e9af9c9d890578182a21e7b71b50334cd5579e
+e63a2115f64433b21cb5dd67c5bf8b30f87ef293
+712ac99e4d0384a941c80a9f48f62943ba7d97c0
+d1474affa8e105bece209cc9d594bb0a989859e1
+2da92388b948821269b18d6b178a680f17e41750
+5062c0c621d887367af8a054e5e5d83d7ec57dd3
 
 # Enable Style/StringLiterals cop for RubyGems/Bundler
 d7ffd3fea402239b16833cc434404a7af82d44f3
@@ -21,3 +27,15 @@ f28287d34c03f472ffe90ea262bdde9affd4b965
 
 # Make benchmark indentation consistent
 fc4acf8cae82e5196186d3278d831f2438479d91
+
+# Make prism_compile.c indentation consistent
+40b2c8e5e7e6e5f83cee9276dc9c1922a69292d6
+d2c5867357ed88eccc28c2b3bd4a46e206e7ff85
+
+# Miss-and-revived commits
+a0f7de814ae5c299d6ce99bed5fb308a05d50ba0
+d4e24021d39e1f80f0055b55d91f8d5f22e15084
+7a56c316418980b8a41fcbdc94067b2bda2ad112
+e90282be7ba1bc8e3119f6e1a2c80356ceb3f80a
+26a9e0b4e31f7b5a9cbd755e0a15823a8fa51bae
+2f53985da9ee593fe524d408256835667938c7d7
diff --git a/.gitattributes b/.gitattributes
index d0c2d266b4..6ac6e6fcc3 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,5 +1,6 @@
 *.gemspec diff=ruby
 *.rb diff=ruby
+*.inc.rs linguist-generated=true
 bin svn-properties=svn:ignore=ruby
 bin/* diff=ruby
 tool/update-deps diff=ruby
diff --git a/.github/actions/capiext/action.yml b/.github/actions/capiext/action.yml
new file mode 100644
index 0000000000..49562725f4
--- /dev/null
+++ b/.github/actions/capiext/action.yml
@@ -0,0 +1,86 @@
+name: rubyspec C-API extensions
+
+inputs:
+  builddir:
+    required: false
+    default: '.'
+  make:
+    required: false
+    default: 'make -s'
+
+outputs:
+  key:
+    value: >-
+      ${{
+      !steps.restore.outputs.cache-hit &&
+      github.ref == 'refs/heads/master' &&
+      steps.config.outputs.key
+      }}
+
+runs:
+  using: composite
+
+  steps:
+    - id: config
+      shell: bash
+      run: |
+        eval $(grep -e '^arch *=' -e '^ruby_version *=' -e '^DLEXT *=' Makefile |
+            sed 's/ *= */=/')
+        case "${ruby_version}" in
+        *+*) key=capiexts-${arch}-${ruby_version}-${{ hashFiles('src/spec/ruby/optional/capi/ext/*.[ch]') }};;
+        *)   key=;;
+        esac
+        echo version=$ruby_version >> $GITHUB_OUTPUT
+        echo key="$key" >> $GITHUB_OUTPUT
+        echo DLEXT=$DLEXT >> $GITHUB_OUTPUT
+      working-directory: ${{ inputs.builddir }}
+
+    - name: Restore previous CAPI extensions
+      uses: actions/cache/restore@0400d5f644dc74513175e3cd8d07132dd4860809 # v4.2.4
+      id: cache
+      with:
+        path: ${{ inputs.builddir }}/spec/ruby/optional/capi/ext/
+        key: ${{ steps.config.outputs.key }}
+      if: ${{ steps.config.outputs.key }}
+
+    - name: Run test-spec with previous CAPI extension binaries
+      id: check
+      shell: bash
+      run: |
+        touch spec/ruby/optional/capi/ext/*.$DLEXT
+        [ ! -f spec/ruby/optional/capi/ext/\*.$DLEXT ]
+        ${{ inputs.make }} SPECOPTS=optional/capi test-spec
+      env:
+        DLEXT: ${{ steps.config.outputs.DLEXT }}
+      working-directory: ${{ inputs.builddir }}
+      if: ${{ steps.cache.outputs.cache-hit }}
+
+    - name: Strip CAPI extensions
+      id: strip
+      shell: bash
+      run: |
+        rm -f spec/ruby/optional/capi/ext/*.c
+        [ "$DLEXT" = bundle ] || # separated to .dSYM directories
+        strip spec/ruby/optional/capi/ext/*.$DLEXT
+      env:
+        DLEXT: ${{ steps.config.outputs.DLEXT }}
+      working-directory: ${{ inputs.builddir }}
+      if: >-
+        ${{true
+        && ! steps.cache.outputs.cache-hit
+        && github.ref_name == 'master'
+        }}
+
+    - name: Save CAPI extensions
+      uses: actions/cache/save@0400d5f644dc74513175e3cd8d07132dd4860809 # v4.2.4
+      with:
+        path: ${{ inputs.builddir }}/spec/ruby/optional/capi/ext/
+        key: ${{ steps.config.outputs.key }}
+      if: ${{ steps.strip.outcome == 'success' }}
+
+    - shell: bash
+      run: |
+        echo "::error::Change from ${prev} detected; bump up ABI version"
+      env:
+        prev: ${{ steps.config.outputs.version }}
+      if: ${{ always() && steps.check.outcome == 'failure' }}
diff --git a/.github/actions/compilers/action.yml b/.github/actions/compilers/action.yml
new file mode 100644
index 0000000000..ab5b56a889
--- /dev/null
+++ b/.github/actions/compilers/action.yml
@@ -0,0 +1,133 @@
+name: Compiles ruby in a container
+description: >-
+  Makes ruby using a dedicated container
+
+inputs:
+  tag:
+    required: false
+    default: clang-20
+    description: >-
+      container image tag to use in this run.
+
+  with_gcc:
+    required: false
+    description: >-
+      override compiler path & flags.
+
+  CFLAGS:
+    required: false
+    description: >-
+      C compiler flags to override.
+
+  CXXFLAGS:
+    required: false
+    description: >-
+      C++ compiler flags to override.
+
+  optflags:
+    required: false
+    # -O1 is faster than -O3 in our tests... Majority of time are consumed trying
+    # to optimize binaries.  Also GitHub Actions run on relatively modern CPUs
+    # compared to, say, GCC 4 or Clang 3.  We don't specify `-march=native`
+    # because compilers tend not understand what the CPU is.
+    default: '-O1'
+    description: >-
+      Compiler flags for optimisations.
+
+  cppflags:
+    required: false
+    description: >-
+      Additional preprocessor flags.
+
+  append_configure:
+    required: false
+    default: >-
+      --without-valgrind
+      --without-jemalloc
+      --without-gmp
+    description: >-
+      flags to append to configure.
+
+  enable_shared:
+    required: false
+    default: true
+    description: >-
+      Whether to build libruby.so.
+
+  check:
+    required: false
+    default: ''
+    description: >-
+      Whether to run `make check`
+
+  test_all:
+    required: false
+    default: ''
+    description: >-
+      Whether to run `make test-all` with options for test-all.
+
+  test_spec:
+    required: false
+    default: ''
+    description: >-
+      Whether to run `make test-spec` with options for mspec.
+
+  static_exts:
+    required: false
+    description: >-
+      whitespace separated list of extensions that need be linked statically.
+
+runs:
+  using: composite
+  steps:
+    - shell: bash
+      run: docker pull --quiet 'ghcr.io/ruby/ruby-ci-image:${{ inputs.tag }}'
+
+    - name: Enable Launchable conditionally
+      id: enable-launchable
+      run: echo "enable-launchable=true" >> $GITHUB_OUTPUT
+      shell: bash
+      if: >-
+        ${{
+        github.repository == 'ruby/ruby' ||
+        (github.repository != 'ruby/ruby' && env.LAUNCHABLE_TOKEN)
+        }}
+
+    - name: compile
+      shell: bash
+      run: >-
+        docker run
+        --rm
+        --user=root
+        --volume '${{ github.workspace }}:/github/workspace:ro'
+        --workdir=/github/workspace
+        --entrypoint=/github/workspace/.github/actions/compilers/entrypoint.sh
+        --env CI
+        --env GITHUB_ACTION
+        --env INPUT_WITH_GCC='${{ inputs.with_gcc || inputs.tag }}'
+        --env INPUT_CFLAGS='${{ inputs.CFLAGS }}'
+        --env INPUT_CXXFLAGS='${{ inputs.CXXFLAGS }}'
+        --env INPUT_OPTFLAGS='${{ inputs.OPTFLAGS }}'
+        --env INPUT_CPPFLAGS='${{ inputs.cppflags }}'
+        --env INPUT_APPEND_CONFIGURE='${{ inputs.append_configure }}'
+        --env INPUT_CHECK='${{ inputs.check }}'
+        --env INPUT_TEST_ALL='${{ inputs.test_all }}'
+        --env INPUT_TEST_SPEC='${{ inputs.test_spec }}'
+        --env INPUT_ENABLE_SHARED='${{ inputs.enable_shared }}'
+        --env INPUT_STATIC_EXTS='${{ inputs.static_exts }}'
+        --env LAUNCHABLE_ORGANIZATION='${{ github.repository_owner }}'
+        --env LAUNCHABLE_WORKSPACE='${{ github.event.repository.name }}'
+        --env LAUNCHABLE_ENABLED='${{ steps.enable-launchable.outputs.enable-launchable || false }}'
+        --env GITHUB_PR_HEAD_SHA='${{ github.event.pull_request.head.sha || github.sha }}'
+        --env GITHUB_PULL_REQUEST_URL='${{ github.event.pull_request.html_url }}'
+        --env GITHUB_REF='${{ github.ref }}'
+        --env GITHUB_ACTIONS
+        --env GITHUB_RUN_ID
+        --env GITHUB_REPOSITORY
+        --env GITHUB_WORKFLOW
+        --env GITHUB_RUN_NUMBER
+        --env GITHUB_EVENT_NAME
+        --env GITHUB_SHA
+        --env GITHUB_HEAD_REF
+        --env GITHUB_SERVER_URL
+        'ghcr.io/ruby/ruby-ci-image:${{ inputs.tag }}'
diff --git a/.github/actions/compilers/entrypoint.sh b/.github/actions/compilers/entrypoint.sh
new file mode 100755
index 0000000000..b554151091
--- /dev/null
+++ b/.github/actions/compilers/entrypoint.sh
@@ -0,0 +1,90 @@
+#! /bin/bash
+
+# Copyright (c) 2024 Ruby developers.  All rights reserved.
+#
+# This file is  a part of the programming language  Ruby.  Permission is hereby
+# granted, to  either redistribute and/or  modify this file, provided  that the
+# conditions  mentioned in  the file  COPYING are  met.  Consult  the file  for
+# details.
+
+grouped()
+{
+    echo "::group::${@}"
+    "${@}"
+    echo "::endgroup::"
+}
+
+set -e
+set -u
+set -o pipefail
+
+srcdir="/github/workspace/src"
+builddir="$(mktemp -dt)"
+
+export GITHUB_WORKFLOW='Compilations'
+export CONFIGURE_TTY='never'
+export RUBY_DEBUG='ci rgengc'
+export RUBY_TESTOPTS='-q --color=always --tty=no'
+export RUBY_DEBUG_COUNTER_DISABLE='1'
+export GNUMAKEFLAGS="-j$((1 + $(nproc)))"
+
+case "x${INPUT_ENABLE_SHARED}" in
+x | xno | xfalse )
+    enable_shared='--disable-shared'
+    ;;
+*)
+    enable_shared='--enable-shared'
+    ;;
+esac
+
+pushd ${builddir}
+
+grouped git config --global --add safe.directory ${srcdir}
+
+grouped ${srcdir}/configure        \
+    -C                             \
+    --with-gcc="${INPUT_WITH_GCC}" \
+    --enable-debug-env             \
+    --disable-install-doc          \
+    --with-ext=-test-/cxxanyargs,+ \
+    --without-git                  \
+    ${enable_shared}               \
+    ${INPUT_APPEND_CONFIGURE}      \
+    CFLAGS="${INPUT_CFLAGS}"       \
+    CXXFLAGS="${INPUT_CXXFLAGS}"   \
+    optflags="${INPUT_OPTFLAGS}"   \
+    cppflags="${INPUT_CPPFLAGS}"   \
+    debugflags='-ggdb3' # -g0 disables backtraces when SEGV.  Do not set that.
+
+popd
+
+if [[ -n "${INPUT_STATIC_EXTS}" ]]; then
+    echo "::group::ext/Setup"
+    set -x
+    mkdir ${builddir}/ext
+    (
+        for ext in ${INPUT_STATIC_EXTS}; do
+            echo "${ext}"
+        done
+    ) >> ${builddir}/ext/Setup
+    set +x
+    echo "::endgroup::"
+fi
+
+if [ -n "$INPUT_TEST_ALL" ]; then
+  tests=" -- $INPUT_TEST_ALL"
+else
+  tests=" -- ruby -ext-"
+fi
+
+pushd ${builddir}
+
+grouped make showflags
+grouped make all
+# grouped make install
+
+# Run only `make test` by default. Run other tests if specified.
+grouped make test
+if [[ -n "$INPUT_CHECK" ]]; then grouped make test-tool; fi
+if [[ -n "$INPUT_CHECK" || -n "$INPUT_TEST_ALL" ]]; then grouped make test-all TESTS="$tests"; fi
+if [[ -n "$INPUT_CHECK" || -n "$INPUT_TEST_SPEC" ]]; then grouped env CHECK_LEAKS=true make test-spec MSPECOPT="$INPUT_TEST_SPEC"; fi
diff --git a/.github/actions/launchable/setup/action.yml b/.github/actions/launchable/setup/action.yml
new file mode 100644
index 0000000000..16af8fc3fd
--- /dev/null
+++ b/.github/actions/launchable/setup/action.yml
@@ -0,0 +1,313 @@
+name: Set up Launchable
+description: >-
+  Install the required dependencies and execute the necessary Launchable commands for test recording
+
+inputs:
+  os:
+    required: true
+    description: The operating system that CI runs on. This value is used in Launchable flavor.
+
+  test-opts:
+    default: none
+    required: false
+    description: >-
+      Test options that determine how tests are run.
+      This value is used in the Launchable flavor.
+
+  launchable-token:
+    required: false
+    description: >-
+      Launchable token is needed if you want to run Launchable on your forked repository.
+      See https://github.com/ruby/ruby/wiki/CI-Servers#launchable-ci for details.
+
+  builddir:
+    required: false
+    default: ${{ github.workspace }}
+    description: >-
+      Directory to create Launchable report file.
+
+  srcdir:
+    required: false
+    default: ${{ github.workspace }}
+    description: >-
+      Directory to (re-)checkout source codes. Launchable retrieves the commit information
+      from the directory.
+
+  test-task:
+    required: false
+    default: ${{ matrix.test_task }}
+    description: >-
+      Specifies a single test task to be executed.
+      This value is used in the Launchable flavor.
+      Either 'test-task' or 'multi-test-tasks' must be configured.
+
+  test-tasks:
+    required: false
+    default: '[]'
+    description: >-
+      Specifies an array of multiple test tasks to be executed.
+      For example: '["test", "test-all"]'.
+      If you want to run a single test task, use the 'test-task' input instead.
+
+  is-yjit:
+    required: false
+    default: 'false'
+    description: >-
+      Whether this workflow is executed on YJIT.
+
+outputs:
+  stdout_report_path:
+    value: ${{ steps.global.outputs.stdout_report_path }}
+    description: >-
+      Report file path for standard output.
+
+  stderr_report_path:
+    value: ${{ steps.global.outputs.stderr_report_path }}
+    description: >-
+      Report file path for standard error.
+
+runs:
+  using: composite
+
+  steps:
+    - name: Enable Launchable conditionally
+      id: enable-launchable
+      run: echo "enable-launchable=true" >> $GITHUB_OUTPUT
+      shell: bash
+      if: >-
+        ${{
+        (github.repository == 'ruby/ruby'
+          || (github.repository != 'ruby/ruby'
+          && env.LAUNCHABLE_TOKEN))
+        && (inputs.test-task == 'check'
+          || inputs.test-task == 'test-all'
+          || inputs.test-task == 'test'
+          || contains(fromJSON(inputs.test-tasks), 'test-all')
+          || contains(fromJSON(inputs.test-tasks), 'test'))
+        }}
+
+    # Launchable CLI requires Python and Java.
+    # https://www.launchableinc.com/docs/resources/cli-reference/
+    - name: Set up Python
+      uses: actions/setup-python@871daa956ca9ea99f3c3e30acb424b7960676734 # v5.0.0
+      with:
+        python-version: "3.x"
+      if: >-
+        ${{ steps.enable-launchable.outputs.enable-launchable
+        && !endsWith(inputs.os, 'ppc64le') && !endsWith(inputs.os, 's390x') }}
+
+    - name: Set up Java
+      uses: actions/setup-java@7a445ee88d4e23b52c33fdc7601e40278616c7f8 # v4.0.0
+      with:
+        distribution: 'temurin'
+        java-version: '17'
+      if: >-
+        ${{ steps.enable-launchable.outputs.enable-launchable
+        && !endsWith(inputs.os, 'ppc64le') && !endsWith(inputs.os, 's390x') }}
+
+    - name: Set up Java ppc64le
+      uses: actions/setup-java@7a445ee88d4e23b52c33fdc7601e40278616c7f8 # v4.0.0
+      with:
+        distribution: 'semeru'
+        architecture: 'ppc64le'
+        java-version: '17'
+      if: >-
+        ${{ steps.enable-launchable.outputs.enable-launchable
+        && endsWith(inputs.os, 'ppc64le') }}
+
+    - name: Set up Java s390x
+      uses: actions/setup-java@7a445ee88d4e23b52c33fdc7601e40278616c7f8 # v4.0.0
+      with:
+        distribution: 'semeru'
+        architecture: 's390x'
+        java-version: '17'
+      if: >-
+        ${{ steps.enable-launchable.outputs.enable-launchable
+        && endsWith(inputs.os, 's390x') }}
+
+    - name: Set global vars
+      id: global
+      shell: bash
+      run: |
+        test_all_enabled="${{ inputs.test-task == 'check' ||  inputs.test-task == 'test-all' || contains(fromJSON(inputs.test-tasks), 'test-all') }}"
+        btest_enabled="${{ inputs.test-task == 'check' ||  inputs.test-task == 'test' || contains(fromJSON(inputs.test-tasks), 'test') }}"
+        test_spec_enabled="${{ inputs.test-task == 'check' ||  inputs.test-task == 'test-spec' || contains(fromJSON(inputs.test-tasks), 'test-spec') }}"
+        echo test_all_enabled="${test_all_enabled}" >> $GITHUB_OUTPUT
+        echo btest_enabled="${btest_enabled}" >> $GITHUB_OUTPUT
+        echo test_spec_enabled="${test_spec_enabled}" >> $GITHUB_OUTPUT
+        echo test_all_report_file='launchable_test_all_report.json' >> $GITHUB_OUTPUT
+        echo btest_report_file='launchable_btest_report.json' >> $GITHUB_OUTPUT
+        echo test_spec_report_dir='launchable_test_spec_report' >> $GITHUB_OUTPUT
+        echo stdout_report_path="launchable_stdout.log" >> $GITHUB_OUTPUT
+        echo stderr_report_path="launchable_stderr.log" >> $GITHUB_OUTPUT
+      if: steps.enable-launchable.outputs.enable-launchable
+
+    - name: Set environment variables for Launchable
+      shell: bash
+      run: |
+        : # GITHUB_PULL_REQUEST_URL are used for commenting test reports in Launchable Github App.
+        : # https://github.com/launchableinc/cli/blob/v1.80.1/launchable/utils/link.py#L42
+        echo "GITHUB_PULL_REQUEST_URL=${{ github.event.pull_request.html_url }}" >> $GITHUB_ENV
+        : # The following envs are necessary in Launchable tokenless authentication.
+        : # https://github.com/launchableinc/cli/blob/v1.80.1/launchable/utils/authentication.py#L20
+        echo "LAUNCHABLE_ORGANIZATION=${{ github.repository_owner }}" >> $GITHUB_ENV
+        echo "LAUNCHABLE_WORKSPACE=${{ github.event.repository.name }}" >> $GITHUB_ENV
+        : # https://github.com/launchableinc/cli/blob/v1.80.1/launchable/utils/authentication.py#L71
+        echo "GITHUB_PR_HEAD_SHA=${{ github.event.pull_request.head.sha || github.sha }}" >> $GITHUB_ENV
+        echo "LAUNCHABLE_TOKEN=${{ inputs.launchable-token }}" >> $GITHUB_ENV
+        : # To prevent a slowdown in CI, disable request retries when the Launchable server is unstable.
+        echo "LAUNCHABLE_SKIP_TIMEOUT_RETRY=1" >> $GITHUB_ENV
+        echo "LAUNCHABLE_COMMIT_TIMEOUT=1" >> $GITHUB_ENV
+      if: steps.enable-launchable.outputs.enable-launchable
+
+    - name: Set up path
+      shell: bash
+      working-directory: ${{ inputs.srcdir }}
+      # Since updated PATH variable will be available in only subsequent actions, we need to add the path beforehand.
+      # https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#adding-a-system-path
+      run: echo "$(python -msite --user-base)/bin" >> $GITHUB_PATH
+      if: >-
+        ${{
+        steps.enable-launchable.outputs.enable-launchable
+        && (startsWith(inputs.os, 'macos')
+          || endsWith(inputs.os, 'ppc64le')
+          || endsWith(inputs.os, 's390x'))
+        }}
+
+    - name: Set up Launchable
+      id: setup-launchable
+      shell: bash
+      working-directory: ${{ inputs.srcdir }}
+      run: |
+        set -x
+        pip install --user launchable
+        : # The build name cannot include a slash, so we replace the string here.
+        github_ref="${{ github.ref }}"
+        github_ref="${github_ref//\//_}"
+        : # With the --name option, we need to configure a unique identifier for this build.
+        : # To avoid setting the same build name as the CI which runs on other branches, we use the branch name here.
+        build_name="${github_ref}_${GITHUB_PR_HEAD_SHA}"
+        test_opts="${{ inputs.test-opts }}"
+        test_opts="${test_opts// /}"
+        test_opts="${test_opts//=/:}"
+        test_all_test_suite='test-all'
+        btest_test_suite='btest'
+        test_spec_test_suite='test-spec'
+        if [ "${{ inputs.is-yjit }}" = "true" ]; then
+          test_all_test_suite="yjit-${test_all_test_suite}"
+          btest_test_suite="yjit-${btest_test_suite}"
+          test_spec_test_suite="yjit-${test_spec_test_suite}"
+        fi
+        # launchable_setup target var -- refers ${target} prefixed variables
+        launchable_setup() {
+          local target=$1 session
+          eval [ "\${${target}_enabled}" = "true" ] || return
+          eval local suite=\${${target}_test_suite}
+          session=$(launchable record session \
+            --build "${build_name}" \
+            --observation \
+            --flavor os="${{ inputs.os }}" \
+            --flavor test_task="${{ inputs.test-task }}" \
+            --flavor test_opts="${test_opts}" \
+            --flavor workflow="${{ github.workflow }}" \
+            --test-suite ${suite} \
+            )
+          echo "${target}_session=${session}" >> $GITHUB_OUTPUT
+        }
+
+        launchable record build --name "${build_name}"
+        if launchable_setup test_all; then
+          echo "TESTS=${TESTS:+$TESTS }--launchable-test-reports=${test_all_report_file}" >> $GITHUB_ENV
+        fi
+        if launchable_setup btest; then
+          echo "BTESTS=${BTESTS:+$BTESTS }--launchable-test-reports=${btest_report_file}" >> $GITHUB_ENV
+        fi
+        if launchable_setup test_spec; then
+          echo "SPECOPTS=${SPECOPTS:$SPECOPTS }--launchable-test-reports=${test_spec_report_dir}" >> $GITHUB_ENV
+          echo test_spec_enabled=true >> $GITHUB_OUTPUT
+        fi
+
+        echo launchable_setup_dir=$(pwd) >> $GITHUB_OUTPUT
+      if: steps.enable-launchable.outputs.enable-launchable
+      env:
+        test_all_enabled: ${{ steps.global.outputs.test_all_enabled }}
+        btest_enabled: ${{ steps.global.outputs.btest_enabled }}
+        test_spec_enabled: ${{ steps.global.outputs.test_spec_enabled }}
+        test_all_report_file: ${{ steps.global.outputs.test_all_report_file }}
+        btest_report_file: ${{ steps.global.outputs.btest_report_file }}
+        test_spec_report_dir: ${{ steps.global.outputs.test_spec_report_dir }}
+
+    - name: make test-spec report directory in build directory
+      shell: bash
+      working-directory: ${{ inputs.builddir }}
+      run: mkdir "${test_spec_report_dir}"
+      if: ${{ steps.setup-launchable.outputs.test_spec_enabled == 'true' }}
+      env:
+        test_spec_report_dir: ${{ steps.global.outputs.test_spec_report_dir }}
+
+    - name: Clean up test results in Launchable
+      uses: gacts/run-and-post-run@674528335da98a7afc80915ff2b4b860a0b3553a # v1.4.0
+      with:
+        shell: bash
+        working-directory: ${{ inputs.builddir }}
+        post: |
+          rm -f "${test_all_report_file}"
+          rm -f "${btest_report_file}"
+          rm -fr "${test_spec_report_dir}"
+          rm -f launchable_stdout.log
+          rm -f launchable_stderr.log
+      if: always() && steps.setup-launchable.outcome == 'success'
+      env:
+        test_all_report_file: ${{ steps.global.outputs.test_all_report_file }}
+        btest_report_file: ${{ steps.global.outputs.btest_report_file }}
+        test_spec_report_dir: ${{ steps.global.outputs.test_spec_report_dir }}
+
+    - name: Record test results in Launchable
+      uses: gacts/run-and-post-run@674528335da98a7afc80915ff2b4b860a0b3553a # v1.4.0
+      with:
+        shell: bash
+        working-directory: ${{ inputs.builddir }}
+        post: |
+          if [[ "${test_all_enabled}" = "true" ]]; then \
+            launchable record attachment \
+              --session "${test_all_session}" \
+              "${stdout_report_path}" \
+              "${stderr_report_path}"; \
+            launchable record tests \
+              --session "${test_all_session}" \
+              raw "${test_all_report_file}" || true; \
+          fi
+
+          if [[ "${btest_enabled}" = "true" ]]; then \
+            launchable record attachment \
+              --session "${btest_session}" \
+              "${stdout_report_path}" \
+              "${stderr_report_path}"; \
+            launchable record tests \
+              --session "${btest_session}" \
+              raw "${btest_report_file}" || true; \
+          fi
+
+          if [[ "${test_spec_enabled}" = "true" ]]; then \
+            launchable record attachment \
+              --session "${test_spec_session}" \
+              "${stdout_report_path}" \
+              "${stderr_report_path}"; \
+            launchable record tests \
+              --session "${test_spec_session}" \
+              raw ${test_spec_report_dir}/* || true; \
+          fi
+      if: ${{ always() && steps.setup-launchable.outcome == 'success' }}
+      env:
+        test_all_report_file: ${{ steps.global.outputs.test_all_report_file }}
+        btest_report_file: ${{ steps.global.outputs.btest_report_file }}
+        test_spec_report_dir: ${{ steps.global.outputs.test_spec_report_dir }}
+        test_all_enabled: ${{ steps.global.outputs.test_all_enabled }}
+        btest_enabled: ${{ steps.global.outputs.btest_enabled }}
+        test_spec_enabled: ${{ steps.global.outputs.test_spec_enabled }}
+        test_all_session: ${{ steps.setup-launchable.outputs.test_all_session }}
+        btest_session: ${{ steps.setup-launchable.outputs.btest_session }}
+        test_spec_session: ${{ steps.setup-launchable.outputs.test_spec_session }}
+        stdout_report_path: ${{ steps.global.outputs.stdout_report_path }}
+        stderr_report_path: ${{ steps.global.outputs.stderr_report_path }}
+        LAUNCHABLE_SETUP_DIR: ${{ steps.setup-launchable.outputs.launchable_setup_dir }}
diff --git a/.github/actions/setup/directories/action.yml b/.github/actions/setup/directories/action.yml
new file mode 100644
index 0000000000..0e8ffd59ef
--- /dev/null
+++ b/.github/actions/setup/directories/action.yml
@@ -0,0 +1,194 @@
+name: Setup directories etc.
+description: >-
+  Set up the source code and build directories (plus some
+  environmental tweaks)
+
+inputs:
+  srcdir:
+    required: false
+    default: ${{ github.workspace }}
+    description: >-
+      Directory to (re-)checkout source codes.  This will be created
+      if absent.  If there is no `configure` file that is also
+      generated inside.
+
+  builddir:
+    required: false
+    default: ${{ github.workspace }}
+    description: >-
+      Where binaries and other generated contents go.  This will be
+      created if absent.
+
+  make-command:
+    required: false
+    type: string
+    default: 'make'
+    description: >-
+      The command of `make`.
+
+  makeup:
+    required: false
+    type: boolean
+    # Note that `default: false` evaluates to a string constant
+    # `'false'`, which is a truthy value :sigh:
+    # https://github.com/actions/runner/issues/2238
+    default: ''
+    description: >-
+      If set to true, additionally runs `make up`.
+
+  checkout:
+    required: false
+    type: boolean
+    default: true
+    description: >-
+      If set to '' (false), skip running actions/checkout. This is useful when
+      you don't want to overwrite a GitHub token that is already set up.
+
+  dummy-files:
+    required: false
+    type: boolean
+    default: ''
+    description: >-
+      If set to true, creates dummy files in build dir.
+
+  fetch-depth:
+    required: false
+    default: '1'
+    description: The depth of commit history fetched from the remote repository
+
+  clean:
+    required: false
+    type: boolean
+    default: ''
+    description: >-
+      If set to true, clean build directory.
+
+outputs: {} # nothing?
+
+runs:
+  using: composite
+
+  steps:
+    # Note that `shell: bash` works on both Windows and Linux, but not
+    # `shell: sh`.  This is because GitHub hosted Windows runners have
+    # their bash manually installed.
+    - shell: bash
+      run: |
+        mkdir -p ${{ inputs.srcdir }}
+        mkdir -p ${{ inputs.builddir }}
+
+    # Did you know that actions/checkout works without git(1)?  We are
+    # checking that here.
+    - id: which
+      shell: bash
+      run: |
+        echo "git=`command -v git`" >> "$GITHUB_OUTPUT"
+        echo "sudo=`sudo true && command -v sudo`" >> "$GITHUB_OUTPUT"
+        echo "autoreconf=`command -v autoreconf`" >> "$GITHUB_OUTPUT"
+
+    - if: steps.which.outputs.git
+      shell: bash
+      run: |
+        git config --global core.autocrlf false
+        git config --global core.eol lf
+        git config --global advice.detachedHead 0
+        git config --global init.defaultBranch garbage
+
+    - if: inputs.checkout
+      uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+      with:
+        path: ${{ inputs.srcdir }}
+        fetch-depth: ${{ inputs.fetch-depth }}
+
+    - uses: actions/cache@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
+      with:
+        path: ${{ inputs.srcdir }}/.downloaded-cache
+        key: ${{ runner.os }}-${{ runner.arch }}-downloaded-cache
+
+    - if: steps.which.outputs.autoreconf
+      shell: bash
+      working-directory: ${{ inputs.srcdir }}
+      run: ./autogen.sh --install
+
+    # This is for MinGW.
+    - if: runner.os == 'Windows'
+      shell: bash
+      run: echo "GNUMAKEFLAGS=-j$((2 * NUMBER_OF_PROCESSORS))" >> $GITHUB_ENV
+
+    - if: runner.os == 'Linux'
+      shell: bash
+      run: echo "GNUMAKEFLAGS=-sj$((1 + $(nproc)))" >> "$GITHUB_ENV"
+
+    # macOS' GNU make is so old that they doesn't understand `GNUMAKEFLAGS`.
+    - if: runner.os == 'macOS'
+      shell: bash
+      run: echo "MAKEFLAGS=-j$((1 + $(sysctl -n hw.activecpu)))" >> "$GITHUB_ENV"
+
+    - if: inputs.makeup
+      shell: bash
+      working-directory: ${{ inputs.srcdir }}
+      run: |
+        touch config.status .rbconfig.time
+        for mk in Makefile GNUmakefile; do
+          sed -f tool/prereq.status template/$mk.in > $mk
+        done
+        make up
+
+    # Cleanup, runs even on failure
+    - if: always() && inputs.makeup
+      shell: bash
+      working-directory: ${{ inputs.srcdir }}
+      run: |
+        rm -f config.status .rbconfig.time \
+          Makefile GNUmakefile uncommon.mk enc.mk noarch-fake.rb
+
+    - if: steps.which.outputs.sudo
+      shell: bash
+      run: |
+        sudo chmod -R go-w /usr/share
+        chmod -v go-w $HOME $HOME/.config || :
+        declare -a dirs # -A is not supported by old bash, e.g. macos
+        SAVE_IFS="$IFS" IFS=:; set $PATH
+        for d do
+          while [ -d "$d" ]; do
+            case "$IFS${dirs[*]}$IFS" in *"$IFS$d$IFS"*) ;; *) dirs+=("$d");; esac
+            d="${d%/*}"
+          done
+        done
+        IFS="$SAVE_IFS"
+        sudo chmod -v go-w "${dirs[@]}" || :
+
+    - if: inputs.dummy-files == 'true'
+      shell: bash
+      id: dummy-files
+      working-directory: ${{ inputs.builddir }}
+      run: |
+        : Create dummy files in build dir
+        set {{a..z},{A..Z},{0..9},foo,bar,test,zzz}.rb
+        for file; do \
+          echo > $file "raise 'do not load $file'"; \
+        done
+        # drop {a..z}.rb if case-insensitive filesystem
+        grep -F A.rb a.rb > /dev/null && set "${@:27}"
+        echo clean="cd ${{ inputs.builddir }} && rm $*" >> $GITHUB_OUTPUT
+
+    - if: inputs.clean == 'true'
+      shell: bash
+      id: clean
+      run: |
+        echo distclean='cd ${{ inputs.builddir }} && ${{ inputs.make-command }} distclean' >> $GITHUB_OUTPUT
+        echo remained-files='find ${{ inputs.builddir }} -ls' >> $GITHUB_OUTPUT
+        [ "${{ inputs.builddir }}" = "${{ inputs.srcdir }}" ] ||
+        echo final='rmdir ${{ inputs.builddir }}' >> $GITHUB_OUTPUT
+
+    - name: clean
+      uses: gacts/run-and-post-run@81b6ce503cde93862cec047c54652e45c5dca991 # v1.4.3
+      with:
+        working-directory:
+        post: |
+          ${{ steps.dummy-files.outputs.clean }}
+          ${{ steps.clean.outputs.distclean }}
+          ${{ steps.clean.outputs.remained-files }}
+          ${{ steps.clean.outputs.final }}
+      # rmdir randomly fails due to launchable files
+      continue-on-error: true
diff --git a/.github/actions/setup/macos/action.yml b/.github/actions/setup/macos/action.yml
new file mode 100644
index 0000000000..d0072ff828
--- /dev/null
+++ b/.github/actions/setup/macos/action.yml
@@ -0,0 +1,29 @@
+name: Setup macOS environment
+description: >-
+  Installs necessary packages via Homebrew.
+
+inputs: {} # nothing?
+
+outputs: {} # nothing?
+
+runs:
+  using: composite
+
+  steps:
+    - name: brew
+      shell: bash
+      run: |
+        brew install --quiet jemalloc gmp libffi openssl@3 zlib autoconf automake libtool
+
+    - name: Set ENV
+      shell: bash
+      run: |
+        dir_config() {
+          local args=() lib var="$1"; shift
+          for lib in "$@"; do
+            args+=("--with-${lib%@*}-dir=$(brew --prefix $lib)")
+          done
+          echo "$var=${args[*]}" >> $GITHUB_ENV
+        }
+        dir_config ruby_configure_args gmp
+        dir_config CONFIGURE_ARGS openssl@3
diff --git a/.github/actions/setup/ubuntu/action.yml b/.github/actions/setup/ubuntu/action.yml
new file mode 100644
index 0000000000..a9e5b41951
--- /dev/null
+++ b/.github/actions/setup/ubuntu/action.yml
@@ -0,0 +1,53 @@
+name: Setup ubuntu environment
+description: >-
+  At the beginning there was no way but to copy & paste `apt-get`
+  everywhere.  But now that we have composite actions, it seems better
+  merge them into one.
+
+inputs:
+  arch:
+    required: false
+    default: ''
+    description: >-
+      Architecture.  Because we run this on a GitHub-hosted runner
+      acceptable value for this input is very limited.
+
+outputs:
+  arch:
+    value: ${{ steps.uname.outputs.uname }}
+    description: >-
+      Actual architecture.  This could be different from the one
+      passed to the `inputs.arch`.  For instance giving `i386` to this
+      action yields `i686`.
+
+runs:
+  using: composite
+
+  steps:
+    - name: set SETARCH
+      shell: bash
+      run: echo "SETARCH=${setarch}" >> "$GITHUB_ENV"
+      env:
+        setarch: ${{ inputs.arch && format('setarch {0} --', inputs.arch) }}
+
+    - id: uname
+      name: uname
+      shell: bash
+      run: |
+        echo uname=`${SETARCH} uname -m` >> "$GITHUB_OUTPUT"
+        echo dpkg=`${SETARCH} uname -m | sed s/686/386/` >> "$GITHUB_OUTPUT"
+
+    - name: apt-get
+      shell: bash
+      env:
+        arch: ${{ inputs.arch && format(':{0}', steps.uname.outputs.dpkg) || '' }}
+      run: |
+        set -x
+        ${arch:+sudo dpkg --add-architecture ${arch#:}}
+        sudo apt-get update -qq || :
+        sudo apt-get install --no-install-recommends -qq -y -o=Dpkg::Use-Pty=0 \
+        ${arch:+cross}build-essential${arch/:/-} \
+        libssl-dev${arch} libyaml-dev${arch} libreadline6-dev${arch} \
+        zlib1g-dev${arch} libncurses5-dev${arch} libffi-dev${arch} \
+        autoconf ruby
+        sudo apt-get install -qq -y pkg-config${arch} || :
diff --git a/.github/actions/slack/action.yml b/.github/actions/slack/action.yml
new file mode 100644
index 0000000000..4a398da1d1
--- /dev/null
+++ b/.github/actions/slack/action.yml
@@ -0,0 +1,51 @@
+name: Post a message to slack
+description: >-
+  We have our ruby/action-slack webhook.  However its arguments are
+  bit verbose to be listed in every workflow files.  Better merge them
+  into one.
+
+inputs:
+  SLACK_WEBHOOK_URL:
+    required: true
+    description: >-
+      The URL to post the payload.  This is an input because it tends
+      to be stored in a secrets vault and a composite action cannot
+      look into one.
+
+  label:
+    required: false
+    description: >-
+      Human-readable description of the run, something like "DEBUG=1".
+      This need not be unique among runs.
+
+  event_name:
+    required: false
+    default: 'push'
+    description: >-
+      Target event to trigger notification. Notify only push by default.
+
+  extra_channel_id:
+    required: false
+    description: >-
+      Slack channel ID to notify besides #alerts and #alerts-emoji.
+
+outputs: {} # Nothing?
+
+runs:
+  using: composite
+
+  steps:
+    - uses: ruby/action-slack@54175162371f1f7c8eb94d7c8644ee2479fcd375 # v3.2.2
+      with:
+        payload: |
+          {
+            "ci": "GitHub Actions",
+            "env": "${{ github.workflow }}${{ inputs.label && format(' / {0}', inputs.label) }}",
+            "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+            "commit": "${{ github.sha }}",
+            "branch": "${{ github.ref_name }}"
+            ${{ inputs.extra_channel_id && format(', "extra_channel_id": "{0}"', inputs.extra_channel_id) }}
+          }
+      env:
+        SLACK_WEBHOOK_URL: ${{ inputs.SLACK_WEBHOOK_URL }}
+      if: ${{ github.event_name == inputs.event_name && startsWith(github.repository, 'ruby/') }}
diff --git a/.github/auto_request_review.yml b/.github/auto_request_review.yml
index d058b6ca00..38496d5ceb 100644
--- a/.github/auto_request_review.yml
+++ b/.github/auto_request_review.yml
@@ -1,9 +1,20 @@
 files:
-  'yjit*': [team:yjit]
-  'yjit/**/*': [team:yjit]
-  'doc/yjit/*': [team:yjit]
-  'bootstraptest/test_yjit*': [team:yjit]
-  'test/ruby/test_yjit*': [team:yjit]
-  '.github/workflows/yjit*': [team:yjit]
+  'yjit*': [team:jit]
+  'yjit/**/*': [team:jit]
+  'yjit/src/cruby_bindings.inc.rs': []
+  'bootstraptest/test_yjit*': [team:jit]
+  'test/ruby/test_yjit*': [team:jit]
+  'zjit*': [team:jit]
+  'zjit/**/*': [team:jit]
+  'zjit/src/cruby_bindings.inc.rs': []
+  'test/ruby/test_zjit*': [team:jit]
+  'defs/jit.mk': [team:jit]
+  'tool/zjit_bisect.rb': [team:jit]
+  'doc/jit/*': [team:jit]
+  # Skip github workflow files because the team don't necessarily need to review dependabot updates for GitHub Actions. It's noisy in notifications, and they're auto-merged anyway.
 options:
   ignore_draft: true
+  # This currently doesn't work as intended. We want to skip reviews when only
+  # cruby_bingings.inc.rs is modified, but this skips reviews even when other
+  # files are modified as well. To be enabled after fixing the behavior.
+  #last_files_match_only: true
diff --git a/.github/codeql/codeql-config.yml b/.github/codeql/codeql-config.yml
deleted file mode 100644
index 6036043d8c..0000000000
--- a/.github/codeql/codeql-config.yml
+++ /dev/null
@@ -1,7 +0,0 @@
-name: "CodeQL config for the Ruby language"
-
-languages: cpp
-
-# syntax_suggest consumes an hour.
-paths-ignore:
-  - lib/syntax_suggest
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index b18fd29357..2c2982d1d4 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -3,4 +3,20 @@ updates:
   - package-ecosystem: 'github-actions'
     directory: '/'
     schedule:
-      interval: 'weekly'
+      interval: 'daily'
+  - package-ecosystem: 'github-actions'
+    directory: '/.github/actions/slack'
+    schedule:
+      interval: 'daily'
+  - package-ecosystem: 'github-actions'
+    directory: '/.github/actions/setup/directories'
+    schedule:
+      interval: 'daily'
+  - package-ecosystem: 'cargo'
+    directory: '/yjit'
+    schedule:
+      interval: 'daily'
+  - package-ecosystem: 'vcpkg'
+    directory: '/'
+    schedule:
+      interval: 'daily'
diff --git a/.github/labeler.yml b/.github/labeler.yml
new file mode 100644
index 0000000000..e81aed8e98
--- /dev/null
+++ b/.github/labeler.yml
@@ -0,0 +1,6 @@
+Documentation:
+- changed-files:
+  - all-globs-to-all-files: doc/**
+
+Backport:
+- base-branch: 'ruby_3_\d'
diff --git a/.github/workflows/annocheck.yml b/.github/workflows/annocheck.yml
new file mode 100644
index 0000000000..899d601aef
--- /dev/null
+++ b/.github/workflows/annocheck.yml
@@ -0,0 +1,110 @@
+name: Annocheck
+
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  compile:
+    name: test-annocheck
+
+    runs-on: ubuntu-latest
+
+    container:
+      image: ghcr.io/ruby/ruby-ci-image:gcc-11
+      options: --user root
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    env:
+      CONFIGURE_TTY: never
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+      RUBY_DEBUG: ci rgengc
+      RUBY_TESTOPTS: >-
+        -q
+        --color=always
+        --tty=no
+      # FIXME: Drop skipping options
+      # https://bugs.ruby-lang.org/issues/18061
+      # https://sourceware.org/annobin/annobin.html/Test-pie.html
+      TEST_ANNOCHECK_OPTS: '--skip-pie --skip-gaps'
+
+    steps:
+      - run: id
+        working-directory:
+
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
+        with:
+          ruby-version: '3.1'
+          bundler: none
+
+      # Minimal flags to pass the check.
+      # -g0 disables backtraces when SEGV.  Do not set that.
+      - name: Run configure
+        run: >
+          ../src/configure -C
+          --enable-debug-env
+          --disable-install-doc
+          --with-ext=-test-/cxxanyargs,+
+          --without-valgrind
+          --without-jemalloc
+          --without-gmp
+          --with-gcc="gcc-11 -fcf-protection -Wa,--generate-missing-build-notes=yes"
+          --enable-shared
+          debugflags=-ggdb3
+          optflags=-O2
+          LDFLAGS=-Wl,-z,now
+
+      - run: make showflags
+
+      - run: make
+
+      - run: make test-annocheck
+
+      - uses: ./.github/actions/slack
+        with:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/auto_request_review.yml b/.github/workflows/auto_request_review.yml
index 7e163de697..207315a084 100644
--- a/.github/workflows/auto_request_review.yml
+++ b/.github/workflows/auto_request_review.yml
@@ -2,13 +2,19 @@ name: Auto Request Review
 on:
   pull_request_target:
     types: [opened, ready_for_review, reopened]
+    branches: [master]
+
+permissions:
+  contents: read
+
 jobs:
   auto-request-review:
     name: Auto Request Review
     runs-on: ubuntu-latest
+    if: ${{ github.repository == 'ruby/ruby' && github.base_ref == 'master' }}
     steps:
       - name: Request review based on files changes and/or groups the author belongs to
-        uses: necojackarc/auto-request-review@e08cdffa277d50854744de3f76230260e61c67f4 # v0.7.0, checking sha
+        uses: necojackarc/auto-request-review@e89da1a8cd7c8c16d9de9c6e763290b6b0e3d424 # v0.13.0
         with:
           # scope: public_repo
-          token: ${{ secrets.MATZBOT_GITHUB_TOKEN }}
+          token: ${{ secrets.MATZBOT_AUTO_REQUEST_REVIEW_TOKEN }}
diff --git a/.github/workflows/auto_review_pr.yml b/.github/workflows/auto_review_pr.yml
new file mode 100644
index 0000000000..ad0e63ba12
--- /dev/null
+++ b/.github/workflows/auto_review_pr.yml
@@ -0,0 +1,33 @@
+name: Auto Review PR
+on:
+  pull_request_target:
+    types: [opened, ready_for_review, reopened]
+    branches: [master]
+
+permissions:
+  contents: read
+
+jobs:
+  auto-review-pr:
+    name: Auto Review PR
+    runs-on: ubuntu-latest
+    if: ${{ github.repository == 'ruby/ruby' && github.base_ref == 'master' }}
+
+    permissions:
+      pull-requests: write
+      contents: read
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6.0.1
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
+        with:
+          ruby-version: '3.4'
+          bundler: none
+
+      - name: Auto Review PR
+        run: ruby tool/auto_review_pr.rb "$GITHUB_PR_NUMBER"
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITHUB_PR_NUMBER: ${{ github.event.pull_request.number }}
diff --git a/.github/workflows/baseruby.yml b/.github/workflows/baseruby.yml
index 1c314da911..d3e734f885 100644
--- a/.github/workflows/baseruby.yml
+++ b/.github/workflows/baseruby.yml
@@ -4,63 +4,71 @@ on:
   push:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
   pull_request:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions:
+  contents: read
+
 jobs:
   baseruby:
     name: BASERUBY
-    runs-on: ubuntu-20.04
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+
+    runs-on: ubuntu-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
     strategy:
       matrix:
         ruby:
-          - ruby-2.2
-#         - ruby-2.3
-#         - ruby-2.4
-#         - ruby-2.5
-#         - ruby-2.6
-#         - ruby-2.7
-          - ruby-3.0
           - ruby-3.1
+          - ruby-3.2
+          - ruby-3.3
 
     steps:
-      - uses: actions/checkout@v3
-      - uses: actions/cache@v3
-        with:
-          path: .downloaded-cache
-          key: downloaded-cache
-      - uses: ruby/setup-ruby@v1
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
         with:
           ruby-version: ${{ matrix.ruby }}
           bundler: none
-      - run: echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
-      - run: sudo apt-get install build-essential autoconf bison libyaml-dev
-      - run: ./autogen.sh
+
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - uses: ./.github/actions/setup/ubuntu
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          makeup: true
+
       - run: ./configure --disable-install-doc
-      - run: make common-srcs
-      - run: make incs
+
       - run: make all
+
       - run: make test
-      - uses: k0kubun/action-slack@v2.0.0
+
+      - uses: ./.github/actions/slack
         with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ github.workflow }} / BASERUBY @ ${{ matrix.ruby }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
-        env:
+          label: ${{ matrix.ruby }}
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ failure() }}
diff --git a/.github/workflows/bundled_gems.yml b/.github/workflows/bundled_gems.yml
index f6f8b9a45b..59f64e8312 100644
--- a/.github/workflows/bundled_gems.yml
+++ b/.github/workflows/bundled_gems.yml
@@ -1,139 +1,190 @@
 name: bundled_gems
 
+env:
+  UPDATE_ENABLED: true
+
 on:
   push:
+    branches: ['master']
     paths:
       - '.github/workflows/bundled_gems.yml'
       - 'gems/bundled_gems'
   pull_request:
+    branches: ['master']
     paths:
       - '.github/workflows/bundled_gems.yml'
       - 'gems/bundled_gems'
+  merge_group:
   schedule:
     - cron: '45 6 * * *'
+  workflow_dispatch:
+
+permissions: # added using https://github.com/step-security/secure-workflows
+  contents: read
 
 jobs:
   update:
+    permissions:
+      contents: write # for Git to git push
+
     if: ${{ github.event_name != 'schedule' || github.repository == 'ruby/ruby' }}
+
     name: update ${{ github.workflow }}
+
     runs-on: ubuntu-latest
+
     steps:
-      - name: git config
-        run: |
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          token: ${{ (github.repository == 'ruby/ruby' && !startsWith(github.event_name, 'pull')) && secrets.MATZBOT_AUTO_UPDATE_TOKEN || secrets.GITHUB_TOKEN }}
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          # Skip overwriting MATZBOT_AUTO_UPDATE_TOKEN
+          checkout: '' # false (ref: https://github.com/actions/runner/issues/2238)
 
       - name: Set ENV
         run: |
-          echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
           echo "TODAY=$(date +%F)" >> $GITHUB_ENV
 
-      - uses: actions/checkout@v3
-
-      - uses: actions/cache@v3
-        with:
-          path: .downloaded-cache
-          key: downloaded-cache-${{ github.sha }}
-          restore-keys: |
-            downloaded-cache
-
       - name: Download previous gems list
         run: |
-          data=bundled_gems.json
           mkdir -p .downloaded-cache
-          ln -s .downloaded-cache/$data .
-          curl -O -R -z ./$data https://stdgems.org/$data
+          for data in bundled_gems.json default_gems.json; do
+            ln -s .downloaded-cache/$data .
+            curl -O -R -z ./$data https://stdgems.org/$data
+          done
 
       - name: Update bundled gems list
+        id: bundled_gems
         run: |
-          ruby -i~ tool/update-bundled_gems.rb gems/bundled_gems
+          ruby -i~ tool/update-bundled_gems.rb gems/bundled_gems >> $GITHUB_OUTPUT
+        if: ${{ env.UPDATE_ENABLED == 'true' }}
 
-      - name: Maintain updated gems list in NEWS
+      - name: Update spec/bundler/support/builders.rb
         run: |
           #!ruby
-          require 'json'
-          news = File.read("NEWS.md")
-          prev = news[/since the \*+(\d+\.\d+\.\d+)\*+/, 1]
-          prevs = [prev, prev.sub(/\.\d+\z/, '')]
-          %W[bundled].each do |type|
-            last = JSON.parse(File.read("#{type}_gems.json"))['gems'].filter_map do |g|
-              v = g['versions'].values_at(*prevs).compact.first
-              g = g['gem']
-              g = 'RubyGems' if g == 'rubygems'
-              [g, v] if v
-            end.to_h
-            changed = File.foreach("gems/#{type}_gems").filter_map do |l|
-              next if l.start_with?("#")
-              g, v = l.split(" ", 3)
-              [g, v] unless last[g] == v
-            end
-            changed, added = changed.partition {|g, _| last[g]}
-            news.sub!(/^\*( +)The following #{type} gems? are updated\.\n\K(?: \1\* .*\n)*/) do
-              mark = "#{$1} * "
-              changed.map {|g, v|"#{mark}#{g} #{v}\n"}.join("")
-            end or next
-            news.sub!(/^\*( +)The following default gems are now bundled gems\.\n\K(?: \1\* .*\n)*/) do
-              mark = "#{$1} * "
-              added.map {|g, v|"#{mark}#{g} #{v}\n"}.join("")
-            end or next if added
-            File.write("NEWS.md", news)
-          end
-        shell: ruby {0}
+          rake_version = File.read("gems/bundled_gems")[/^rake\s+(\S+)/, 1]
+          print ARGF.read.sub(/^ *def rake_version\s*\K".*?"/) {rake_version.dump}
+        shell: ruby -i~ {0} spec/bundler/support/builders.rb
+        if: ${{ env.UPDATE_ENABLED == 'true' }}
+
+      - name: Maintain updated gems list in NEWS
+        run: |
+          ruby tool/update-NEWS-gemlist.rb bundled
+        if: ${{ env.UPDATE_ENABLED == 'true' }}
 
       - name: Check diffs
         id: diff
         run: |
-          git add -- NEWS.md
-          git diff --no-ext-diff --ignore-submodules --quiet -- gems/bundled_gems
-        continue-on-error: true
+          news= gems=
+          git diff --color --no-ext-diff --ignore-submodules --exit-code -- NEWS.md ||
+          news=true
+          git diff --color --no-ext-diff --ignore-submodules --exit-code -- gems/bundled_gems ||
+          gems=true
+          git add -- NEWS.md gems/bundled_gems
+          git add -- spec/bundler/support/builders.rb
+          echo news=$news >> $GITHUB_OUTPUT
+          echo gems=$gems >> $GITHUB_OUTPUT
+          echo update=${news:-$gems} >> $GITHUB_OUTPUT
 
-      - name: Install libraries
+      - name: Commit
+        id: commit
         run: |
-          set -x
-          sudo apt-get update -q || :
-          sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev bison autoconf ruby
-        if: ${{ steps.diff.outcome == 'failure' }}
+          git pull --ff-only origin ${GITHUB_REF#refs/heads/}
+          message="Update bundled gems list"
+          if [ -z "${gems}" ]; then
+            git commit --message="[DOC] ${message} at ${GITHUB_SHA:0:30}"
+          else
+            git commit --message="${message} as of ${TODAY}"
+          fi
+        env:
+          TODAY: ${{ steps.bundled_gems.outputs.latest_date || env.TODAY }}
+          EMAIL: svn-admin@ruby-lang.org
+          GIT_AUTHOR_NAME: git
+          GIT_COMMITTER_NAME: git
+          gems: ${{ steps.diff.outputs.gems }}
+        if: ${{ steps.diff.outputs.update }}
+
+      - name: Development revision of bundled gems
+        run: |
+          #!ruby
+          file = "gems/bundled_gems"
+
+          SECONDS_IN_DAY = 86400
+          today = Time.new("#{ENV['TODAY']}Z")
+          if !(december = today.month == 12)
+            days = 30
+          elsif (days = 26 - today.day).positive?
+            days += 4
+          else
+            puts "::info:: just after released"
+            exit
+          end
+
+          since = "#{today.year-1}-12-26"
+          ref = ENV['GITHUB_REF']
+          puts "::group::\e[94mfetching \e[1m#{file}\e[22m since \e[1m#{since}\e[22m from \e[1m#{ref}\e[m"
+          system(*%W[git fetch --shallow-since=#{since} --no-tags origin #{ref}], exception: true)
+          puts "::endgroup::"
+
+          puts "\e[94mchecking development version bundled gems older than \e[1m#{days}\e[22m days\e[m"
+          limit = today.to_i - days * SECONDS_IN_DAY
+          old = 0
+          IO.popen(%W"git blame --line-porcelain -- #{file}") do |blame|
+            while head = blame.gets("\n\t") and s = blame.gets
+              next unless (gem = s.split(/\s+|#.*/)).size > 3
+              time = head[/^committer-time \K\d+/].to_i
+              next if (d = limit - time) <= 0
+              d /= SECONDS_IN_DAY
+              line = head[/\A\h+ \d+ \K\d+/].to_i
+              level = if d < days; 'warning'; else old += 1; 'error'; end
+              d += days
+              puts "::#{level} file=#{file},line=#{line},title=Older than #{d} days::#{gem[0]} #{gem[3]}"
+            end
+          end
+          abort "::error title=Too long-standing gems::The release comes soon." if december and old.nonzero?
+        shell: ruby {0}
+        env:
+          file: ${{ steps.logs.outputs.file }}
+          days: ${{ steps.logs.outputs.days }}
+
+      - name: Install libraries
+        uses: ./.github/actions/setup/ubuntu
+        if: ${{ steps.diff.outputs.gems }}
 
       - name: Build
         run: |
           ./autogen.sh
           ./configure -C --disable-install-doc
           make
-        if: ${{ steps.diff.outcome == 'failure' }}
+        if: ${{ steps.diff.outputs.gems }}
 
       - name: Prepare bundled gems
         run: |
           make -s prepare-gems
-        if: ${{ steps.diff.outcome == 'failure' }}
+        if: ${{ steps.diff.outputs.gems }}
 
       - name: Test bundled gems
         run: |
           make -s test-bundled-gems
-          git add -- gems/bundled_gems
         timeout-minutes: 30
         env:
-          RUBY_TESTOPTS: "-q --tty=no"
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ""
-        if: ${{ steps.diff.outcome == 'failure' }}
-
-      - name: Show diffs
-        id: show
-        run: |
-          git diff --cached --color --no-ext-diff --ignore-submodules --exit-code --
-        continue-on-error: true
+          RUBY_TESTOPTS: '-q --tty=no'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
+        if: ${{ steps.diff.outputs.gems }}
 
-      - name: Commit
+      - name: Push
         run: |
-          git pull --ff-only origin ${GITHUB_REF#refs/heads/}
-          message="Update bundled gems list at "
-          if [ ${{ steps.diff.outcome }} = success ]; then
-            git commit --message="${message}${GITHUB_SHA:0:30} [ci skip]"
-          else
-            git commit --message="${message}${TODAY}"
-          fi
           git push origin ${GITHUB_REF#refs/heads/}
-        env:
-          EMAIL: svn-admin@ruby-lang.org
-          GIT_AUTHOR_NAME: git
-          GIT_COMMITTER_NAME: git
-        if: ${{ github.repository == 'ruby/ruby' && !startsWith(github.event_name, 'pull') && steps.show.outcome == 'failure' }}
+        if: >-
+          ${{
+          github.repository == 'ruby/ruby' &&
+          !startsWith(github.event_name, 'pull') &&
+          steps.commit.outcome == 'success'
+          }}
+
+      - uses: ./.github/actions/slack
+        with:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
diff --git a/.github/workflows/check_dependencies.yml b/.github/workflows/check_dependencies.yml
index fab1989335..c5dec65e48 100644
--- a/.github/workflows/check_dependencies.yml
+++ b/.github/workflows/check_dependencies.yml
@@ -3,65 +3,57 @@ on:
   push:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   pull_request:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions:
+  contents: read
+
 jobs:
   update-deps:
+    name: Dependency checks
+
     strategy:
       matrix:
-        os: [ubuntu-20.04]
+        os: [ubuntu-latest]
       fail-fast: true
+
     runs-on: ${{ matrix.os }}
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+
     steps:
-      - name: Install libraries
-        run: |
-          set -x
-          sudo apt-get update -q || :
-          sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev bison autoconf ruby
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - uses: ./.github/actions/setup/ubuntu
         if: ${{ contains(matrix.os, 'ubuntu') }}
-      - name: Install libraries
-        run: |
-          brew upgrade
-          brew install gmp libffi openssl@1.1 zlib autoconf automake libtool readline
+
+      - uses: ./.github/actions/setup/macos
         if: ${{ contains(matrix.os, 'macos') }}
-      - name: git config
-        run: |
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v3
-      - uses: actions/cache@v3
+
+      - uses: ./.github/actions/setup/directories
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
         with:
-          path: .downloaded-cache
-          key: downloaded-cache
-      - run: ./autogen.sh
+          ruby-version: '3.1'
+          bundler: none
+
       - name: Run configure
         run: ./configure -C --disable-install-doc --disable-rubygems --with-gcc 'optflags=-O0' 'debugflags=-save-temps=obj -g'
-      - run: make all golf
-      - run: ruby tool/update-deps --fix
+
+      - run: make fix-depends
+
       - run: git diff --no-ext-diff --ignore-submodules --exit-code
-      - uses: k0kubun/action-slack@v2.0.0
+
+      - uses: ./.github/actions/slack
         with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ matrix.os }} / Dependencies need to update",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
-        env:
+          label: ${{ matrix.os }} / Dependencies need to update
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ failure() }}
diff --git a/.github/workflows/check_misc.yml b/.github/workflows/check_misc.yml
index 32a07f7fd6..2a2bd1df53 100644
--- a/.github/workflows/check_misc.yml
+++ b/.github/workflows/check_misc.yml
@@ -1,99 +1,127 @@
-name: Miscellaneous checks
-on: [push, pull_request]
+name: Misc
+on: [push, pull_request, merge_group]
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions:
+  contents: read
+
 jobs:
   checks:
+    name: Miscellaneous checks
+
+    permissions:
+      contents: write # for Git to git push
+
     runs-on: ubuntu-latest
+
     steps:
-      - uses: actions/checkout@v3
-      - name: Check if C-sources are US-ASCII
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          token: ${{ (github.repository == 'ruby/ruby' && !startsWith(github.event_name, 'pull')) && secrets.MATZBOT_AUTO_UPDATE_TOKEN || secrets.GITHUB_TOKEN }}
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          makeup: true
+          # Skip overwriting MATZBOT_AUTO_UPDATE_TOKEN
+          checkout: '' # false (ref: https://github.com/actions/runner/issues/2238)
+
+      - name: Check for code styles
         run: |
-          ! grep -r -n '[^	 -~]' *.[chy] include internal win32/*.[ch]
-      - name: Check for trailing spaces
+          set -x
+          ruby tool/auto-style.rb "$GITHUB_OLD_SHA" "$GITHUB_NEW_SHA"
+        env:
+          GITHUB_OLD_SHA: ${{ github.event.pull_request.base.sha }}
+          GITHUB_NEW_SHA: ${{ github.event.pull_request.merge_commit_sha }}
+        # Skip 'push' events because post_push.yml fixes them on push
+        if: ${{ github.repository == 'ruby/ruby' && startsWith(github.event_name, 'pull') }}
+
+      - name: Check for bash specific substitution in configure.ac
         run: |
-          ! git grep -n '[	 ]$' '*.rb' '*.[chy]'
+          git grep -n '\${[A-Za-z_0-9]*/' -- configure.ac && exit 1 || :
+
       - name: Check for header macros
         run: |
-          ! for header in ruby/*.h; do \
-            git grep -l -F -e $header -e HAVE_`echo $header | tr a-z./ A-Z__` -- . > /dev/null || echo $header
-          done | grep -F .
+          fail=
+          for header in ruby/*.h; do
+            git grep -l -F -e $header -e HAVE_`echo $header | tr a-z./ A-Z__` -- . > /dev/null && continue
+            fail=1
+            echo $header
+          done
+          exit $fail
         working-directory: include
 
-      - uses: actions/cache@v3
-        with:
-          path: .downloaded-cache
-          key: downloaded-cache-${{ github.sha }}
-          restore-keys: |
-            downloaded-cache
+      - id: now
+        run: |
+          date +"mon=%-m"%n"day=%-d" >> $GITHUB_OUTPUT
+        env:
+          TZ: Tokyo/Asia
 
-      - name: Download previous gems list
+      - id: deprecation
         run: |
-          data=default_gems.json
-          mkdir -p .downloaded-cache
-          ln -s .downloaded-cache/$data .
-          curl -O -R -z ./$data https://stdgems.org/$data
+          eval $(sed -n 's/^#define RUBY_API_VERSION_\(MAJOR\|MINOR\) /\1=/p' include/ruby/version.h)
+          if git --no-pager grep --color -o 'rb_warn_deprecated_to_remove_at('$MAJOR'\.'$MINOR',.*' -- '*.c' >&2; then
+              false
+          else
+              true
+          fi
+        continue-on-error: ${{ steps.now.outputs.mon < 12 }}
 
-      - name: Make default gems list
+      - name: Check if to generate documents
+        id: rdoc
         run: |
-          #!ruby
-          require 'rubygems'
-          $:.unshift "lib"
-          rgver = File.foreach("lib/rubygems.rb") do |line|
-            break $1 if /^\s*VERSION\s*=\s*"([^"]+)"/ =~ line
-          end
-          gems = Dir.glob("{ext,lib}/**/*.gemspec").map do |f|
-            spec = Gem::Specification.load(f)
-            "#{spec.name} #{spec.version}"
-          end.sort
-          File.open("gems/default_gems", "w") do |f|
-            f.puts "RubyGems #{rgver}"
-            f.puts gems
-          end
-        shell: ruby --disable=gems {0}
-
-      - name: Maintain updated gems list in NEWS
+          set -- $(sed 's/#.*//;/^rdoc /!d' gems/bundled_gems)
+          { echo version=$2; echo ref=$4; } >> $GITHUB_OUTPUT
+          echo RDOC='ruby -W0 --disable-gems tool/rdoc-srcdir -q' >> $GITHUB_ENV
+
+      - name: Checkout rdoc
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          repository: ruby/rdoc
+          ref: ${{ steps.rdoc.outputs.ref }}
+          path: .bundle/gems/rdoc-${{ steps.rdoc.outputs.version }}
+        if: ${{ steps.rdoc.outputs.ref != '' }}
+
+      - name: Generate rdoc
         run: |
-          #!ruby
-          require 'json'
-          news = File.read("NEWS.md")
-          prev = news[/since the \*+(\d+\.\d+\.\d+)\*+/, 1]
-          prevs = [prev, prev.sub(/\.\d+\z/, '')]
-          %W[default].each do |type|
-            last = JSON.parse(File.read("#{type}_gems.json"))['gems'].filter_map do |g|
-              v = g['versions'].values_at(*prevs).compact.first
-              g = g['gem']
-              g = 'RubyGems' if g == 'rubygems'
-              [g, v] if v
-            end.to_h
-            changed = File.foreach("gems/#{type}_gems").filter_map do |l|
-              next if l.start_with?("#")
-              g, v = l.split(" ", 3)
-              [g, v] unless last[g] == v
-            end
-            news.sub!(/^\*( +)The following #{type} gems? are updated\.\n\K(?: \1\* .*\n)*/) do
-              mark = "#{$1} * "
-              changed.map {|g, v|"#{mark}#{g} #{v}\n"}.join("")
-            end or next
-            File.write("NEWS.md", news)
-          end
-        shell: ruby {0}
-
-      - name: Check diffs
-        id: diff
+          set -x
+          gempath=$(ruby -e 'print Gem.user_dir, "/bin"')
+          PATH=$gempath:$PATH
+          gem install --user bundler
+          bundle config --local path vendor/bundle
+          bundle install --jobs 4
+          bundle exec rake generate
+        working-directory: .bundle/gems/rdoc-${{ steps.rdoc.outputs.version }}
+        if: ${{ steps.rdoc.outputs.ref != '' }}
+
+      - name: Core docs coverage
         run: |
-          git diff --color --no-ext-diff --ignore-submodules --exit-code NEWS.md
-        continue-on-error: true
-      - name: Commit
+          $RDOC -C -x ^ext -x ^lib .
+
+      - name: Generate docs
+        id: docs
         run: |
-          git pull --ff-only origin ${GITHUB_REF#refs/heads/}
-          git commit --message="Update default gems list at ${GITHUB_SHA:0:30} [ci skip]" NEWS.md
-          git push origin ${GITHUB_REF#refs/heads/}
-        env:
-          EMAIL: svn-admin@ruby-lang.org
-          GIT_AUTHOR_NAME: git
-          GIT_COMMITTER_NAME: git
-        if: ${{ github.repository == 'ruby/ruby' && !startsWith(github.event_name, 'pull') && steps.diff.outcome == 'failure' }}
+          $RDOC --op html .
+          echo htmlout=ruby-html-${GITHUB_SHA:0:10} >> $GITHUB_OUTPUT
+        # Generate only when document commit/PR
+        if: >-
+          ${{false
+          || contains(github.event.head_commit.message, '[ruby/rdoc]')
+          || contains(github.event.head_commit.message, '[DOC]')
+          || contains(github.event.pull_request.title, '[DOC]')
+          || contains(github.event.pull_request.labels.*.name, 'Documentation')
+          }}
+
+      - name: Upload docs
+        uses: actions/upload-artifact@v6.0.0
+        with:
+          path: html
+          name: ${{ steps.docs.outputs.htmlout }}
+        if: ${{ steps.docs.outcome == 'success' }}
+
+      - uses: ./.github/actions/slack
+        with:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index f9fa0a7449..a92c93b476 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -1,63 +1,121 @@
-name: "Code scanning - action"
+name: 'CodeQL'
 
 on:
   push:
+    branches: ['master']
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   pull_request:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   schedule:
-    - cron: '0 12 * * 4'
+    - cron: '0 12 * * *'
+  workflow_dispatch:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
-jobs:
-  CodeQL-Build:
+permissions: # added using https://github.com/step-security/secure-workflows
+  contents: read
 
-    # CodeQL runs on ubuntu-latest and windows-latest
+jobs:
+  analyze:
+    name: Analyze
     runs-on: ubuntu-latest
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+    permissions:
+      actions: read # for github/codeql-action/init to get workflow details
+      contents: read # for actions/checkout to fetch code
+      security-events: write # for github/codeql-action/autobuild to send a status report
+    # CodeQL fails to run pull requests from dependabot due to missing write access to upload results.
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
 
     env:
       enable_install_doc: no
 
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - language: cpp
+          - language: ruby
+
     steps:
-    - name: Install libraries
-      run: |
-        set -x
-        sudo apt-get update -q || :
-        sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev bison autoconf ruby
+      - name: Checkout repository
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - name: Install libraries
+        if: ${{ contains(matrix.os, 'macos') }}
+        uses: ./.github/actions/setup/macos
+
+      - name: Install libraries
+        if : ${{ matrix.os == 'ubuntu-latest' }}
+        uses: ./.github/actions/setup/ubuntu
 
-    - name: Checkout repository
-      uses: actions/checkout@v3
+      - uses: ./.github/actions/setup/directories
 
-    - uses: actions/cache@v3
-      with:
-        path: .downloaded-cache
-        key: downloaded-cache
+      - name: Remove an obsolete rubygems vendored file
+        if: ${{ matrix.os == 'ubuntu-latest' }}
+        run: sudo rm /usr/lib/ruby/vendor_ruby/rubygems/defaults/operating_system.rb
 
-    - name: Remove an obsolete rubygems vendored file
-      run: sudo rm /usr/lib/ruby/vendor_ruby/rubygems/defaults/operating_system.rb
+      - name: Initialize CodeQL
+        uses: github/codeql-action/init@e296a935590eb16afc0c0108289f68c87e2a89a5 # v4.30.7
+        with:
+          languages: ${{ matrix.language }}
+          trap-caching: false
+          debug: true
 
-    - name: Initialize CodeQL
-      uses: github/codeql-action/init@v2
-      with:
-        config-file: ./.github/codeql/codeql-config.yml
+      - name: Autobuild
+        uses: github/codeql-action/autobuild@e296a935590eb16afc0c0108289f68c87e2a89a5 # v4.30.7
 
-    - name: Set ENV
-      run: echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
+      - name: Perform CodeQL Analysis
+        uses: github/codeql-action/analyze@e296a935590eb16afc0c0108289f68c87e2a89a5 # v4.30.7
+        with:
+          category: '/language:${{ matrix.language }}'
+          upload: False
+          output: sarif-results
 
-    - name: Autobuild
-      uses: github/codeql-action/autobuild@v2
+      - name: filter-sarif
+        uses: advanced-security/filter-sarif@f3b8118a9349d88f7b1c0c488476411145b6270d # v1.0.1
+        with:
+          patterns: |
+            +**/*.rb
+            -lib/uri/mailto.rb:rb/overly-large-range
+            -lib/uri/rfc3986_parser.rb:rb/overly-large-range
+            -lib/bundler/vendor/uri/lib/uri/mailto.rb:rb/overly-large-range
+            -lib/bundler/vendor/uri/lib/uri/rfc3986_parser.rb:rb/overly-large-range
+            -test/ruby/test_io.rb:rb/non-constant-kernel-open
+            -test/open-uri/test_open-uri.rb:rb/non-constant-kernel-open
+            -test/open-uri/test_ssl.rb:rb/non-constant-kernel-open
+            -spec/ruby/core/io/binread_spec.rb:rb/non-constant-kernel-open
+            -spec/ruby/core/io/readlines_spec.rb:rb/non-constant-kernel-open
+            -spec/ruby/core/io/foreach_spec.rb:rb/non-constant-kernel-open
+            -spec/ruby/core/io/write_spec.rb:rb/non-constant-kernel-open
+            -spec/ruby/core/io/read_spec.rb:rb/non-constant-kernel-open
+            -spec/ruby/core/kernel/open_spec.rb:rb/non-constant-kernel-open
+          input: sarif-results/${{ matrix.language }}.sarif
+          output: sarif-results/${{ matrix.language }}.sarif
+        if: ${{ matrix.language == 'ruby' }}
+        continue-on-error: true
 
-    - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v2
+      - name: Upload SARIF
+        uses: github/codeql-action/upload-sarif@e296a935590eb16afc0c0108289f68c87e2a89a5 # v4.30.7
+        with:
+          sarif_file: sarif-results/${{ matrix.language }}.sarif
+        continue-on-error: true
diff --git a/.github/workflows/compilers.yml b/.github/workflows/compilers.yml
index 70d0e3ae6c..8c0ca54e0b 100644
--- a/.github/workflows/compilers.yml
+++ b/.github/workflows/compilers.yml
@@ -1,282 +1,334 @@
+# Some tests depending on this name 'Compilations' via $GITHUB_WORKFLOW. Make sure to update such tests when renaming this workflow.
 name: Compilations
 
 on:
   push:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   pull_request:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
-# GitHub actions does not support YAML anchors.  This creative use of
-# environment variables (plus the "echo $GITHUB_ENV" hack) is to reroute that
-# restriction.
-env:
-  default_cc: clang-15
-  append_cc: ''
-
-  # -O1 is faster than -O3 in our tests... Majority of time are consumed trying
-  # to optimize binaries.  Also GitHub Actions run on relatively modern CPUs
-  # compared to, say, GCC 4 or Clang 3.  We don't specify `-march=native`
-  # because compilers tend not understand what the CPU is.
-  optflags: '-O1'
-
-  # -g0 disables backtraces when SEGV.  Do not set that.
-  debugflags: '-ggdb3'
-
-  default_configure: >-
-    --enable-debug-env
-    --disable-install-doc
-    --with-ext=-test-/cxxanyargs,+
-  append_configure: >-
-    --without-valgrind
-    --without-jemalloc
-    --without-gmp
-
-  UPDATE_UNICODE: >-
-    UNICODE_FILES=.
-    UNICODE_PROPERTY_FILES=.
-    UNICODE_AUXILIARY_FILES=.
-    UNICODE_EMOJI_FILES=.
-  CONFIGURE_TTY: never
-  GITPULLOPTIONS: --no-tags origin ${{github.ref}}
-  RUBY_DEBUG: ci rgengc
-  RUBY_TESTOPTS: >-
-    -q
-    --color=always
-    --tty=no
+permissions:
+  contents: read
 
+# Each job is split so that they roughly take 30min to run through.
 jobs:
-  compile:
-    strategy:
-      fail-fast: false
-      matrix:
-        env:
-          - {}
-        entry:
-          - { name: gcc-12,    env: { default_cc: gcc-12 } }
-          - { name: gcc-11,    env: { default_cc: gcc-11 } }
-          - { name: gcc-10,    env: { default_cc: gcc-10 } }
-          - { name: gcc-9,     env: { default_cc: gcc-9 } }
-          - { name: gcc-8,     env: { default_cc: gcc-8 } }
-          - { name: gcc-7,     env: { default_cc: gcc-7 } }
-          - { name: gcc-6,     env: { default_cc: gcc-6 } }
-          - { name: gcc-5,     env: { default_cc: gcc-5 } }
-          - { name: gcc-4.8,   env: { default_cc: gcc-4.8 } }
-          - name: 'gcc-11 LTO'
-            container: gcc-11
-            env:
-              default_cc: 'gcc-11 -flto=auto -ffat-lto-objects'
-              optflags: '-O2'
-            shared: disable
-            # check: true
-          - name: 'gcc-11 annocheck'
-            container: gcc-11
-            env:
-              # Minimal flags to pass the check.
-              default_cc: 'gcc-11 -O2 -fcf-protection -Wa,--generate-missing-build-notes=yes'
-              LDFLAGS: '-Wl,-z,now'
-              # FIXME: Drop skipping options
-              # https://bugs.ruby-lang.org/issues/18061
-              # https://sourceware.org/annobin/annobin.html/Test-pie.html
-              TEST_ANNOCHECK_OPTS: "--skip-pie"
-            check: true
-          - { name: clang-16,  env: { default_cc: clang-16 } }
-          - { name: clang-15,  env: { default_cc: clang-15 } }
-          - { name: clang-14,  env: { default_cc: clang-14 } }
-          - { name: clang-13,  env: { default_cc: clang-13 } }
-          - { name: clang-12,  env: { default_cc: clang-12 } }
-          - { name: clang-11,  env: { default_cc: clang-11 } }
-          - { name: clang-10,  env: { default_cc: clang-10 } }
-          - { name: clang-9,   env: { default_cc: clang-9 } }
-          - { name: clang-8,   env: { default_cc: clang-8 } }
-          - { name: clang-7,   env: { default_cc: clang-7 } }
-          - { name: clang-6.0, env: { default_cc: clang-6.0 } }
-          - { name: clang-5.0, env: { default_cc: clang-5.0 } }
-          - { name: clang-4.0, env: { default_cc: clang-4.0 } }
-          - { name: clang-3.9, env: { default_cc: clang-3.9 } }
-          - name: 'clang-14 LTO'
-            container: clang-14
-            env:
-              default_cc: 'clang-14 -flto=auto'
-              optflags: '-O2'
-            shared: disable
-            # check: true
-
-#         - { name: aarch64-linux-gnu,     crosshost: aarch64-linux-gnu, container: crossbuild-essential-arm64 }
-#         - { name: arm-linux-gnueabi,     crosshost: arm-linux-gnueabi }
-#         - { name: arm-linux-gnueabihf,   crosshost: arm-linux-gnueabihf }
-#         - { name: i686-w64-mingw32,      crosshost: i686-w64-mingw32 }
-#         - { name: powerpc-linux-gnu,     crosshost: powerpc-linux-gnu }
-#         - { name: powerpc64le-linux-gnu, crosshost: powerpc64le-linux-gnu, container: crossbuild-essential-ppc64el }
-#         - { name: s390x-linux-gnu,       crosshost: s390x-linux-gnu, container: crossbuild-essential-s390x }
-#         - { name: x86_64-w64-mingw32,    crosshost: x86_64-w64-mingw32, container: mingw-w64 }
-
-          # -Wno-strict-prototypes is necessary with current clang-15 since
-          # older autoconf generate functions without prototype and -pedantic
-          # now implies strict-prototypes. Disabling the error but leaving the
-          # warning generates a lot of noise from use of ANYARGS in
-          # rb_define_method() and friends.
-          # See: https://github.com/llvm/llvm-project/commit/11da1b53d8cd3507959022cd790d5a7ad4573d94
-          - { name: c99,   env: { append_cc: '-std=c99   -Werror=pedantic -pedantic-errors -Wno-strict-prototypes' } }
-#         - { name: c11,   env: { append_cc: '-std=c11   -Werror=pedantic -pedantic-errors -Wno-strict-prototypes' } }
-#         - { name: c17,   env: { append_cc: '-std=c17   -Werror=pedantic -pedantic-errors -Wno-strict-prototypes' } }
-          - { name: c2x,   env: { append_cc: '-std=c2x   -Werror=pedantic -pedantic-errors -Wno-strict-prototypes' } }
-          - { name: c++98, env: { CXXFLAGS: '-std=c++98 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' } }
-#         - { name: c++11, env: { CXXFLAGS: '-std=c++11 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' } }
-#         - { name: c++14, env: { CXXFLAGS: '-std=c++14 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' } }
-#         - { name: c++17, env: { CXXFLAGS: '-std=c++17 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' } }
-          - { name: c++2a, env: { CXXFLAGS: '-std=c++2a -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' } }
-
-          - { name: '-O0', env: { optflags: '-O0 -march=x86-64 -mtune=generic' } }
-#         - { name: '-O3', env: { optflags: '-O3 -march=x86-64 -mtune=generic' }, check: true }
-
-          - { name: gmp,                  env: { append_configure: '--with-gmp' } }
-          - { name: jemalloc,             env: { append_configure: '--with-jemalloc' } }
-          - { name: valgrind,             env: { append_configure: '--with-valgrind' } }
-          - { name: 'coroutine=ucontext', env: { append_configure: '--with-coroutine=ucontext' } }
-          - { name: 'coroutine=pthread',  env: { append_configure: '--with-coroutine=pthread' } }
-          - { name: disable-jit-support,  env: { append_configure: '--disable-jit-support' } }
-          - { name: disable-dln,          env: { append_configure: '--disable-dln' } }
-          - { name: enable-mkmf-verbose,  env: { append_configure: '--enable-mkmf-verbose' } }
-          - { name: disable-rubygems,     env: { append_configure: '--disable-rubygems' } }
-          - { name: RUBY_DEVEL,           env: { append_configure: '--enable-devel' } }
+  compile-if:
+    name: 'omnibus compilations, trigger'
+    runs-on: ubuntu-latest
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+    steps:
+      - run: true
+        working-directory:
 
-          - { name: OPT_THREADED_CODE=1,            env: { cppflags: '-DOPT_THREADED_CODE=1' } }
-          - { name: OPT_THREADED_CODE=2,            env: { cppflags: '-DOPT_THREADED_CODE=2' } }
-          - { name: OPT_THREADED_CODE=3,            env: { cppflags: '-DOPT_THREADED_CODE=3' } }
+  compile1:
+    name: 'omnibus compilations, #1'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      # Set fetch-depth: 10 so that Launchable can receive commits information.
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - name: 'clang 18 LTO'
+        uses: './.github/actions/compilers'
+        with:
+          tag: clang-18
+          with_gcc: 'clang-18 -flto=auto'
+          optflags: '-O2'
+          enable_shared: false
+        timeout-minutes: 30
+      - { uses: './.github/actions/compilers', name: '-O0', with: { optflags: '-O0 -march=x86-64 -mtune=generic' }, timeout-minutes: 5 }
+      # - { uses: './.github/actions/compilers', name: '-O3', with: { optflags: '-O3 -march=x86-64 -mtune=generic', check: true } }
 
-          - { name: NDEBUG,                         env: { cppflags: '-DNDEBUG' } }
-          - { name: RUBY_DEBUG,                     env: { cppflags: '-DRUBY_DEBUG' } }
-#         - { name: ARRAY_DEBUG,                    env: { cppflags: '-DARRAY_DEBUG' } }
-#         - { name: BIGNUM_DEBUG,                   env: { cppflags: '-DBIGNUM_DEBUG' } }
-#         - { name: CCAN_LIST_DEBUG,                env: { cppflags: '-DCCAN_LIST_DEBUG' } }
-#         - { name: CPDEBUG=-1,                     env: { cppflags: '-DCPDEBUG=-1' } }
-#         - { name: ENC_DEBUG,                      env: { cppflags: '-DENC_DEBUG' } }
-#         - { name: GC_DEBUG,                       env: { cppflags: '-DGC_DEBUG' } }
-#         - { name: HASH_DEBUG,                     env: { cppflags: '-DHASH_DEBUG' } }
-#         - { name: ID_TABLE_DEBUG,                 env: { cppflags: '-DID_TABLE_DEBUG' } }
-#         - { name: RGENGC_DEBUG=-1,                env: { cppflags: '-DRGENGC_DEBUG=-1' } }
-#         - { name: SYMBOL_DEBUG,                   env: { cppflags: '-DSYMBOL_DEBUG' } }
+  compile2:
+    name: 'omnibus compilations, #2'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - name: 'GCC 15 LTO'
+        uses: './.github/actions/compilers'
+        with:
+          tag: gcc-15
+          with_gcc: 'gcc-15 -flto=auto -ffat-lto-objects -Werror=lto-type-mismatch'
+          optflags: '-O2'
+          enable_shared: false
+        timeout-minutes: 10
+      - { uses: './.github/actions/compilers', name: 'ext/Setup', with: { static_exts: 'etc json/* */escape' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GCC 15', with: { tag: 'gcc-15' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GCC 14', with: { tag: 'gcc-14' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GCC 13', with: { tag: 'gcc-13' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GCC 12', with: { tag: 'gcc-12' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GCC 11', with: { tag: 'gcc-11' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GCC 10', with: { tag: 'gcc-10' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GCC 9',  with: { tag: 'gcc-9'  }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GCC 8',  with: { tag: 'gcc-8'  }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GCC 7',  with: { tag: 'gcc-7'  }, timeout-minutes: 5 }
 
-#         - { name: RGENGC_CHECK_MODE,              env: { cppflags: '-DRGENGC_CHECK_MODE' } }
-#         - { name: TRANSIENT_HEAP_CHECK_MODE,      env: { cppflags: '-DTRANSIENT_HEAP_CHECK_MODE' } }
-#         - { name: VM_CHECK_MODE,                  env: { cppflags: '-DVM_CHECK_MODE' } }
+  compile3:
+    name: 'omnibus compilations, #3'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - { uses: './.github/actions/compilers', name: 'clang 22', with: { tag: 'clang-22' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 21', with: { tag: 'clang-21' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 20', with: { tag: 'clang-20' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 19', with: { tag: 'clang-19' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 18', with: { tag: 'clang-18' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 17', with: { tag: 'clang-17' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 16', with: { tag: 'clang-16' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 15', with: { tag: 'clang-15' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 14', with: { tag: 'clang-14' }, timeout-minutes: 5 }
 
-          - { name: USE_EMBED_CI=0,                 env: { cppflags: '-DUSE_EMBED_CI=0' } }
-          - { name: USE_FLONUM=0,                   env: { cppflags: '-DUSE_FLONUM=0' } }
-#         - { name: USE_GC_MALLOC_OBJ_INFO_DETAILS, env: { cppflags: '-DUSE_GC_MALLOC_OBJ_INFO_DETAILS' } }
-          - { name: USE_LAZY_LOAD,                  env: { cppflags: '-DUSE_LAZY_LOAD' } }
-#         - { name: USE_RINCGC=0,                   env: { cppflags: '-DUSE_RINCGC=0' } }
-#         - { name: USE_SYMBOL_GC=0,                env: { cppflags: '-DUSE_SYMBOL_GC=0' } }
-#         - { name: USE_THREAD_CACHE=0,             env: { cppflags: '-DUSE_THREAD_CACHE=0' } }
-#         - { name: USE_TRANSIENT_HEAP=0,           env: { cppflags: '-DUSE_TRANSIENT_HEAP=0' } }
-#         - { name: USE_RUBY_DEBUG_LOG=1,           env: { cppflags: '-DUSE_RUBY_DEBUG_LOG=1' } }
-          - { name: USE_RVARGC=0,                   env: { cppflags: '-DUSE_RVARGC=0' } }
-#         - { name: USE_RVARGC=1,                   env: { cppflags: '-DUSE_RVARGC=1' } }
-#         - { name: USE_DEBUG_COUNTER,              env: { cppflags: '-DUSE_DEBUG_COUNTER=1', RUBY_DEBUG_COUNTER_DISABLE: '1' } }
+  compile4:
+    name: 'omnibus compilations, #4'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - { uses: './.github/actions/compilers', name: 'clang 13', with: { tag: 'clang-13' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 12', with: { tag: 'clang-12' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 11', with: { tag: 'clang-11' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 10', with: { tag: 'clang-10' }, timeout-minutes: 5 }
+        # llvm-objcopy<=9 doesn't have --wildcard. It compiles, but leaves Rust symbols in libyjit.o and fail `make test-leaked-globals`.
+      - { uses: './.github/actions/compilers', name: 'clang 9',  with: { tag: 'clang-9',   append_configure: '--disable-yjit --disable-zjit' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 8',  with: { tag: 'clang-8',   append_configure: '--disable-yjit --disable-zjit' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 7',  with: { tag: 'clang-7',   append_configure: '--disable-yjit --disable-zjit' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'clang 6',  with: { tag: 'clang-6.0', append_configure: '--disable-yjit --disable-zjit' }, timeout-minutes: 5 }
 
-          - { name: DEBUG_FIND_TIME_NUMGUESS,       env: { cppflags: '-DDEBUG_FIND_TIME_NUMGUESS' } }
-          - { name: DEBUG_INTEGER_PACK,             env: { cppflags: '-DDEBUG_INTEGER_PACK' } }
-#         - { name: ENABLE_PATH_CHECK,              env: { cppflags: '-DENABLE_PATH_CHECK' } }
+  compile5:
+    name: 'omnibus compilations, #5'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      # -Wno-strict-prototypes is necessary with current clang-15 since
+      # older autoconf generate functions without prototype and -pedantic
+      # now implies strict-prototypes. Disabling the error but leaving the
+      # warning generates a lot of noise from use of ANYARGS in
+      # rb_define_method() and friends.
+      # See: https://github.com/llvm/llvm-project/commit/11da1b53d8cd3507959022cd790d5a7ad4573d94
+      - { uses: './.github/actions/compilers', name: 'C99',      with: { CFLAGS: '-std=c99 -Werror=pedantic -pedantic-errors -Wno-strict-prototypes' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'C11',   with: { CFLAGS:   '-std=c11   -Werror=pedantic -pedantic-errors -Wno-strict-prototypes' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'C17',   with: { CFLAGS:   '-std=c17   -Werror=pedantic -pedantic-errors -Wno-strict-prototypes' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'C23',   with: { CFLAGS:   '-std=c2x   -Werror=pedantic -pedantic-errors -Wno-strict-prototypes' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'C++98', with: { CXXFLAGS: '-std=c++98 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'C++11', with: { CXXFLAGS: '-std=c++11 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'C++14', with: { CXXFLAGS: '-std=c++14 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'C++17', with: { CXXFLAGS: '-std=c++17 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }, timeout-minutes: 5 }
 
-          - { name: GC_DEBUG_STRESS_TO_CLASS,       env: { cppflags: '-DGC_DEBUG_STRESS_TO_CLASS' } }
-#         - { name: GC_ENABLE_LAZY_SWEEP=0,         env: { cppflags: '-DGC_ENABLE_LAZY_SWEEP=0' } }
-#         - { name: GC_PROFILE_DETAIL_MEMOTY,       env: { cppflags: '-DGC_PROFILE_DETAIL_MEMOTY' } }
-#         - { name: GC_PROFILE_MORE_DETAIL,         env: { cppflags: '-DGC_PROFILE_MORE_DETAIL' } }
+  compile6:
+    name: 'omnibus compilations, #6'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - { uses: './.github/actions/compilers', name: 'C++20', with: { CXXFLAGS: '-std=c++20 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'C++23', with: { CXXFLAGS: '-std=c++23 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'C++26', with: { CXXFLAGS: '-std=c++26 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'gmp',                 with: { append_configure: '--with-gmp', test_all: 'ruby/test_bignum.rb', test_spec: "/github/workspace/src/spec/ruby/core/integer" }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'jemalloc',            with: { append_configure: '--with-jemalloc' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'valgrind',            with: { append_configure: '--with-valgrind' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'coroutine=ucontext',  with: { append_configure: '--with-coroutine=ucontext' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'coroutine=pthread',   with: { append_configure: '--with-coroutine=pthread' }, timeout-minutes: 5 }
 
-#         - { name: CALC_EXACT_MALLOC_SIZE,         env: { cppflags: '-DCALC_EXACT_MALLOC_SIZE' } }
-#         - { name: MALLOC_ALLOCATED_SIZE_CHECK,    env: { cppflags: '-DMALLOC_ALLOCATED_SIZE_CHECK' } }
+  compile7:
+    name: 'omnibus compilations, #7'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - { uses: './.github/actions/compilers', name: 'disable-jit',         with: { append_configure: '--disable-yjit --disable-zjit' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'disable-yjit',        with: { append_configure: '--disable-yjit' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'disable-zjit',        with: { append_configure: '--disable-zjit' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'disable-dln',         with: { append_configure: '--disable-dln' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'enable-mkmf-verbose', with: { append_configure: '--enable-mkmf-verbose' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'disable-rubygems',    with: { append_configure: '--disable-rubygems' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'RUBY_DEVEL',          with: { append_configure: '--enable-devel' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'OPT_THREADED_CODE=0',            with: { cppflags: '-DOPT_THREADED_CODE=0' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'OPT_THREADED_CODE=1',            with: { cppflags: '-DOPT_THREADED_CODE=1' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'OPT_THREADED_CODE=2',            with: { cppflags: '-DOPT_THREADED_CODE=2' }, timeout-minutes: 5 }
 
-#         - { name: IBF_ISEQ_ENABLE_LOCAL_BUFFER,   env: { cppflags: '-DIBF_ISEQ_ENABLE_LOCAL_BUFFER' } }
+  compile8:
+    name: 'omnibus compilations, #8'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - { uses: './.github/actions/compilers', name: 'NDEBUG',                         with: { cppflags: '-DNDEBUG' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'RUBY_DEBUG',                     with: { cppflags: '-DRUBY_DEBUG' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'ARRAY_DEBUG',                    with: { cppflags: '-DARRAY_DEBUG' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'BIGNUM_DEBUG',                   with: { cppflags: '-DBIGNUM_DEBUG' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'CCAN_LIST_DEBUG',                with: { cppflags: '-DCCAN_LIST_DEBUG' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'CPDEBUG=-1',                     with: { cppflags: '-DCPDEBUG=-1' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'ENC_DEBUG',                      with: { cppflags: '-DENC_DEBUG' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GC_DEBUG',                       with: { cppflags: '-DGC_DEBUG' }, timeout-minutes: 5 }
 
-#         - { name: RGENGC_ESTIMATE_OLDMALLOC,      env: { cppflags: '-DRGENGC_ESTIMATE_OLDMALLOC' } }
-#         - { name: RGENGC_FORCE_MAJOR_GC,          env: { cppflags: '-DRGENGC_FORCE_MAJOR_GC' } }
-#         - { name: RGENGC_OBJ_INFO,                env: { cppflags: '-DRGENGC_OBJ_INFO' } }
-#         - { name: RGENGC_OLD_NEWOBJ_CHECK,        env: { cppflags: '-DRGENGC_OLD_NEWOBJ_CHECK' } }
-#         - { name: RGENGC_PROFILE,                 env: { cppflags: '-DRGENGC_PROFILE' } }
+  compile9:
+    name: 'omnibus compilations, #9'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - { uses: './.github/actions/compilers', name: 'HASH_DEBUG',                     with: { cppflags: '-DHASH_DEBUG' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'ID_TABLE_DEBUG',                 with: { cppflags: '-DID_TABLE_DEBUG' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'RGENGC_DEBUG=-1',                with: { cppflags: '-DRGENGC_DEBUG=-1' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'SYMBOL_DEBUG',                   with: { cppflags: '-DSYMBOL_DEBUG' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'RGENGC_CHECK_MODE',              with: { cppflags: '-DRGENGC_CHECK_MODE' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'VM_CHECK_MODE',                  with: { cppflags: '-DVM_CHECK_MODE' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'USE_EMBED_CI=0',                 with: { cppflags: '-DUSE_EMBED_CI=0' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'USE_FLONUM=0',                   with: { cppflags: '-DUSE_FLONUM=0', append_configure: '--disable-yjit --disable-zjit' }, timeout-minutes: 5 }
 
-#         - { name: VM_DEBUG_BP_CHECK,              env: { cppflags: '-DVM_DEBUG_BP_CHECK' } }
-#         - { name: VM_DEBUG_VERIFY_METHOD_CACHE,   env: { cppflags: '-DVM_DEBUG_VERIFY_METHOD_CACHE' } }
+  compileX:
+    name: 'omnibus compilations, #10'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - { uses: './.github/actions/compilers', name: 'USE_LAZY_LOAD',                  with: { cppflags: '-DUSE_LAZY_LOAD' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'USE_SYMBOL_GC=0',                with: { cppflags: '-DUSE_SYMBOL_GC=0' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'USE_THREAD_CACHE=0',             with: { cppflags: '-DUSE_THREAD_CACHE=0' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'USE_RUBY_DEBUG_LOG=1',           with: { cppflags: '-DUSE_RUBY_DEBUG_LOG=1' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'USE_DEBUG_COUNTER',              with: { cppflags: '-DUSE_DEBUG_COUNTER=1' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'SHARABLE_MIDDLE_SUBSTRING',      with: { cppflags: '-DSHARABLE_MIDDLE_SUBSTRING=1' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'DEBUG_FIND_TIME_NUMGUESS',       with: { cppflags: '-DDEBUG_FIND_TIME_NUMGUESS' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'DEBUG_INTEGER_PACK',             with: { cppflags: '-DDEBUG_INTEGER_PACK' }, timeout-minutes: 5 }
 
-          - { name: MJIT_FORCE_ENABLE,              env: { cppflags: '-DMJIT_FORCE_ENABLE' } }
-          - { name: YJIT_FORCE_ENABLE,              env: { cppflags: '-DYJIT_FORCE_ENABLE' } }
+  compileB:
+    name: 'omnibus compilations, #11'
+    runs-on: ubuntu-latest
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - { uses: './.github/actions/compilers', name: 'GC_DEBUG_STRESS_TO_CLASS',       with: { cppflags: '-DGC_DEBUG_STRESS_TO_CLASS' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GC_ENABLE_LAZY_SWEEP=0',         with: { cppflags: '-DGC_ENABLE_LAZY_SWEEP=0' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GC_PROFILE_DETAIL_MEMORY',       with: { cppflags: '-DGC_PROFILE_DETAIL_MEMORY' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'GC_PROFILE_MORE_DETAIL',         with: { cppflags: '-DGC_PROFILE_MORE_DETAIL' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'MALLOC_ALLOCATED_SIZE_CHECK',    with: { cppflags: '-DMALLOC_ALLOCATED_SIZE_CHECK' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'RGENGC_ESTIMATE_OLDMALLOC',      with: { cppflags: '-DRGENGC_ESTIMATE_OLDMALLOC' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'RGENGC_PROFILE',                 with: { cppflags: '-DRGENGC_PROFILE' }, timeout-minutes: 5 }
 
-    name: ${{ matrix.entry.name }}
+  compileC:
+    name: 'omnibus compilations, #12'
     runs-on: ubuntu-latest
-    container:
-      image: ghcr.io/ruby/ruby-ci-image:${{ matrix.entry.container || matrix.entry.env.default_cc || 'clang-15' }}
-      options: --user root
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
-    env: ${{ matrix.entry.env || matrix.env }}
+    needs: compile-if
+    if: ${{ needs.compile-if.result == 'success' }}
+    timeout-minutes: 60
+    services: { docuum: { image: 'stephanmisc/docuum', options: '--init', volumes: [ '/root', '/var/run/docker.sock:/var/run/docker.sock' ] } }
     steps:
-      - run: id
-        working-directory:
-      - run: mkdir build
-        working-directory:
-      - name: setenv
-        run: |
-          echo "GNUMAKEFLAGS=-sj$((1 + $(nproc --all)))" >> $GITHUB_ENV
-      - uses: actions/checkout@v3
-        with:
-          path: src
-      - uses: actions/cache@v3
-        with:
-          path: src/.downloaded-cache
-          key: downloaded-cache
-      - run: ./autogen.sh
-        working-directory: src
-      - name: Run configure
-        run: >
-          ../src/configure -C ${default_configure} ${append_configure}
-          --${{
-            matrix.entry.crosshost && 'host' || 'with-gcc'
-          }}=${{
-            matrix.entry.crosshost || '"${default_cc}${append_cc:+ $append_cc}"'
-          }}
-          --${{ matrix.entry.shared || 'enable' }}-shared
-      - run: make extract-extlibs
-      - run: make incs
-      - run: make showflags
-      - run: make
-      - run: make leaked-globals
-      - run: make test
-      - run: make install
-        if: ${{ matrix.entry.check }}
-      - run: make test-tool
-        if: ${{ matrix.entry.check }}
-      - run: make test-all TESTS='-- ruby -ext-'
-        if: ${{ matrix.entry.check }}
-      - run: make test-spec
-        env:
-          CHECK_LEAKS: true
-        if: ${{ matrix.entry.check }}
-      - run: make test-annocheck
-        if: ${{ matrix.entry.check && endsWith(matrix.entry.name, 'annocheck') }}
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - { uses: './.github/actions/setup/directories', with: { srcdir: 'src', builddir: 'build', makeup: true, fetch-depth: 10 } }
+      - { uses: './.github/actions/compilers', name: 'VM_DEBUG_BP_CHECK',              with: { cppflags: '-DVM_DEBUG_BP_CHECK' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'VM_DEBUG_VERIFY_METHOD_CACHE',   with: { cppflags: '-DVM_DEBUG_VERIFY_METHOD_CACHE' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'YJIT_FORCE_ENABLE',              with: { cppflags: '-DYJIT_FORCE_ENABLE' }, timeout-minutes: 5 }
+      - { uses: './.github/actions/compilers', name: 'UNIVERSAL_PARSER',               with: { cppflags: '-DUNIVERSAL_PARSER' }, timeout-minutes: 5 }
 
-      - uses: k0kubun/action-slack@v2.0.0
+  compilemax:
+    name: 'omnibus compilations, result'
+    runs-on: ubuntu-latest
+    if: ${{ always() }}
+    needs:
+      - 'compile1'
+      - 'compile2'
+      - 'compile3'
+      - 'compile4'
+      - 'compile5'
+      - 'compile6'
+      - 'compile7'
+      - 'compile8'
+      - 'compile9'
+      - 'compileX'
+      - 'compileB'
+      - 'compileC'
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with: { sparse-checkout-cone-mode: false, sparse-checkout: /.github }
+      - uses: ./.github/actions/slack
         with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ github.workflow }} / ${{ matrix.entry.name }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
-        env:
+          label: 'omnibus'
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
+      - run: false
+        working-directory:
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
 
 defaults:
   run:
diff --git a/.github/workflows/cygwin.yml b/.github/workflows/cygwin.yml
new file mode 100644
index 0000000000..ac73991fe8
--- /dev/null
+++ b/.github/workflows/cygwin.yml
@@ -0,0 +1,71 @@
+name: Cygwin
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  make:
+    runs-on: windows-2022
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - run: git config --global core.autocrlf input
+
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - name: Setup Cygwin
+        uses: cygwin/cygwin-install-action@master
+        with:
+          packages: ruby gcc-core make autoconf libtool libssl-devel libyaml-devel libffi-devel zlib-devel rubygems
+
+      - name: configure
+        run: |
+          ./autogen.sh
+          ./configure --disable-install-doc
+        shell: C:\cygwin\bin\bash.EXE --noprofile --norc -e -o igncr -o pipefail {0}
+
+      - name: Extract bundled gems
+        run: |
+          make ruby -j5
+          make extract-gems
+        shell: C:\cygwin\bin\bash.EXE --noprofile --norc -e -o igncr -o pipefail {0}
+
+      - name: make all
+        timeout-minutes: 30
+        run: make -j4 V=1
+        shell: C:\cygwin\bin\bash.EXE --noprofile --norc -e -o igncr -o pipefail {0}
+
+      - uses: ./.github/actions/slack
+        with:
+          label: Cygwin
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
diff --git a/.github/workflows/default_gems_list.yml b/.github/workflows/default_gems_list.yml
new file mode 100644
index 0000000000..1c7e2195c8
--- /dev/null
+++ b/.github/workflows/default_gems_list.yml
@@ -0,0 +1,99 @@
+name: Update default gems list
+on: [push, pull_request, merge_group]
+
+env:
+  UPDATE_NEWS_ENABLED: true
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  update_default_gems_list:
+    name: Update default gems list
+
+    permissions:
+      contents: write # for Git to git push
+
+    runs-on: ubuntu-latest
+
+    if: ${{ github.repository == 'ruby/ruby' }}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          token: ${{ (github.repository == 'ruby/ruby' && !startsWith(github.event_name, 'pull')) && secrets.MATZBOT_AUTO_UPDATE_TOKEN || secrets.GITHUB_TOKEN }}
+
+      - id: gems
+        run: true
+        if: ${{ github.ref == 'refs/heads/master' }}
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          makeup: true
+          # Skip overwriting MATZBOT_AUTO_UPDATE_TOKEN
+          checkout: '' # false (ref: https://github.com/actions/runner/issues/2238)
+        if: ${{ steps.gems.outcome == 'success' }}
+
+      - name: Download previous gems list
+        run: |
+          data=default_gems.json
+          mkdir -p .downloaded-cache
+          ln -s .downloaded-cache/$data .
+          curl -O -R -z ./$data https://stdgems.org/$data
+        if: ${{ steps.gems.outcome == 'success' }}
+
+      - name: Make default gems list
+        run: |
+          #!ruby
+          require 'rubygems'
+          $:.unshift "lib"
+          rgver = File.foreach("lib/rubygems.rb") do |line|
+            break $1 if /^\s*VERSION\s*=\s*"([^"]+)"/ =~ line
+          end
+          gems = Dir.glob("{ext,lib}/**/*.gemspec").map do |f|
+            spec = Gem::Specification.load(f)
+            "#{spec.name} #{spec.version}"
+          end.sort
+          File.open("gems/default_gems", "w") do |f|
+            f.puts "RubyGems #{rgver}"
+            f.puts gems
+          end
+        shell: ruby --disable=gems {0}
+        if: ${{ steps.gems.outcome == 'success' }}
+
+      - name: Maintain updated gems list in NEWS
+        run: |
+          ruby tool/update-NEWS-gemlist.rb default
+        if: ${{ steps.gems.outcome == 'success' && env.UPDATE_NEWS_ENABLED == 'true' }}
+
+      - name: Check diffs
+        id: diff
+        run: |
+          git diff --color --no-ext-diff --ignore-submodules --exit-code NEWS.md ||
+          echo update=true >> $GITHUB_OUTPUT
+        if: ${{ steps.gems.outcome == 'success' }}
+
+      - name: Commit
+        run: |
+          git pull --ff-only origin ${GITHUB_REF#refs/heads/}
+          git commit --message="Update default gems list at ${GITHUB_SHA:0:30} [ci skip]" NEWS.md
+          git push origin ${GITHUB_REF#refs/heads/}
+        env:
+          EMAIL: svn-admin@ruby-lang.org
+          GIT_AUTHOR_NAME: git
+          GIT_COMMITTER_NAME: git
+        if: >-
+          ${{
+          github.repository == 'ruby/ruby' &&
+          !startsWith(github.event_name, 'pull') &&
+          steps.diff.outputs.update
+          }}
+
+      - uses: ./.github/actions/slack
+        with:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
diff --git a/.github/workflows/dependabot_automerge.yml b/.github/workflows/dependabot_automerge.yml
new file mode 100644
index 0000000000..a95c7005c4
--- /dev/null
+++ b/.github/workflows/dependabot_automerge.yml
@@ -0,0 +1,32 @@
+# from https://github.com/gofiber/swagger/blob/main/.github/workflows/dependabot_automerge.yml
+name: Dependabot auto-merge
+on:
+  pull_request:
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  automerge:
+    runs-on: ubuntu-latest
+    if: github.event.pull_request.user.login == 'dependabot[bot]' && github.repository == 'ruby/ruby'
+    steps:
+      - name: Dependabot metadata
+        uses: dependabot/fetch-metadata@21025c705c08248db411dc16f3619e6b5f9ea21a # v2.5.0
+        id: metadata
+
+      - name: Wait for status checks
+        uses: lewagon/wait-on-check-action@3603e826ee561ea102b58accb5ea55a1a7482343 # v1.4.1
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
+          check-regexp: 'make \(check, .*\)'
+          wait-interval: 30
+
+      - name: Auto-merge for Dependabot PRs
+        if: ${{ steps.metadata.outputs.update-type == 'version-update:semver-minor' || steps.metadata.outputs.update-type == 'version-update:semver-patch' }}
+        run: gh pr merge --auto --rebase "$PR_URL"
+        env:
+          PR_URL: ${{ github.event.pull_request.html_url }}
+          GITHUB_TOKEN: ${{ secrets.MATZBOT_DEPENDABOT_MERGE_TOKEN }}
diff --git a/.github/workflows/labeler.yml b/.github/workflows/labeler.yml
new file mode 100644
index 0000000000..16dbac1afa
--- /dev/null
+++ b/.github/workflows/labeler.yml
@@ -0,0 +1,12 @@
+name: "Pull Request Labeler"
+on:
+- pull_request_target
+
+jobs:
+  labeler:
+    permissions:
+      contents: read
+      pull-requests: write
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/labeler@v6
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 72f28a7b61..29adcab39a 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -3,97 +3,199 @@ on:
   push:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   pull_request:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions:
+  contents: read
+
 jobs:
   make:
     strategy:
       matrix:
-        test_task: ["check"] # "test-bundler-parallel", "test-bundled-gems"
-        os:
-          - macos-11
-          - macos-12
+        include:
+          - test_task: check
+            os: macos-14
+          - test_task: check
+            os: macos-14
+            configure_args: '--with-gcc=gcc-14'
+          - test_task: check
+            os: macos-14
+            configure_args: '--with-jemalloc --with-opt-dir=$(brew --prefix jemalloc)'
+          - test_task: check
+            os: macos-14
+            configure_args: '--with-gmp'
+          - test_task: test-all
+            test_opts: --repeat-count=2
+            os: macos-14
+          - test_task: test-bundler-parallel
+            os: macos-14
+          - test_task: test-bundled-gems
+            os: macos-14
+          - test_task: check
+            os: macos-15
       fail-fast: false
+
     env:
-      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+
     runs-on: ${{ matrix.os }}
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
     steps:
-      - run: mkdir build
-        working-directory:
-      - name: git config
-        run: |
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v3
-        with:
-          path: src
-      - uses: actions/cache@v3
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
-          path: src/.downloaded-cache
-          key: downloaded-cache
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
       - name: Install libraries
+        uses: ./.github/actions/setup/macos
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          clean: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
+          # Set fetch-depth: 0 so that Launchable can receive commits information.
+          fetch-depth: 10
+
+      - name: make sure that kern.coredump=1
         run: |
-          brew upgrade
-          brew install gmp libffi openssl@1.1 zlib autoconf automake libtool readline
-        working-directory: src
-      - name: Set ENV
+          sysctl -n kern.coredump
+          sudo sysctl -w kern.coredump=1
+          sudo chmod -R +rwx /cores/
+
+      - name: Delete unused SDKs
+        # To free up disk space to not run out during the run
         run: |
-          echo "MAKEFLAGS=-j$((1 + $(sysctl -n hw.activecpu)))" >> $GITHUB_ENV
-      - run: ./autogen.sh
-        working-directory: src
+          sudo rm -rf ~/.dotnet
+          sudo rm -rf /Library/Android
+          sudo rm -rf /Library/Developer/CoreSimulator
+        continue-on-error: true
+
       - name: Run configure
-        run: ../src/configure -C --disable-install-doc --with-openssl-dir=$(brew --prefix openssl@1.1) --with-readline-dir=$(brew --prefix readline)
-      - run: make incs
+        run: ../src/configure -C --disable-install-doc ${ruby_configure_args} ${{ matrix.configure_args }}
+
       - run: make prepare-gems
         if: ${{ matrix.test_task == 'test-bundled-gems' }}
+
       - run: make
-      - run: make leaked-globals
-        if: ${{ matrix.test_task == 'check' }}
+
+      - run: make hello
+
+      - name: runirb
+        run: |
+          echo IRB::VERSION | make runirb RUNOPT="-- -f"
+
+      - name: Set test options for skipped tests
+        run: |
+          set -x
+          TESTS="$(echo "${{ matrix.skipped_tests }}" | sed 's| |$$/ -n!/|g;s|^|-n!/|;s|$|$$/|')"
+          echo "TESTS=${TESTS}" >> $GITHUB_ENV
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
+
+      - name: Set up Launchable
+        id: launchable
+        uses: ./.github/actions/launchable/setup
+        with:
+          os: ${{ matrix.os }}
+          test-opts: ${{ matrix.test_opts }}
+          launchable-token: ${{ secrets.LAUNCHABLE_TOKEN }}
+          builddir: build
+          srcdir: src
+        continue-on-error: true
+        timeout-minutes: 3
+
+      - name: Set extra test options
+        run: |
+          echo "TESTS=$TESTS ${{ matrix.test_opts }}" >> $GITHUB_ENV
+          echo "RUBY_TEST_TIMEOUT_SCALE=10" >> $GITHUB_ENV # With --repeat-count=2, flaky test by timeout occurs frequently for some reason
+        if: matrix.test_opts
+
       - name: make ${{ matrix.test_task }}
         run: |
-          make -s ${{ matrix.test_task }} ${TESTS:+TESTS=`echo "$TESTS" | sed 's| |$$/ -n!/|g;s|^|-n!/|;s|$|$$/|'`}
-        timeout-minutes: 40
+          test -n "${LAUNCHABLE_STDOUT}" && exec 1> >(tee "${LAUNCHABLE_STDOUT}")
+          test -n "${LAUNCHABLE_STDERR}" && exec 2> >(tee "${LAUNCHABLE_STDERR}")
+
+          ulimit -c unlimited
+          make -s ${{ matrix.test_task }} ${TESTS:+TESTS="$TESTS"}
+        timeout-minutes: 90
         env:
-          RUBY_TESTOPTS: "-q --tty=no"
-          TESTS: ${{ matrix.test_task == 'check' && matrix.skipped_tests || '' }}
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ""
-          PRECHECK_BUNDLED_GEMS: "no"
+          RUBY_TESTOPTS: '-q --tty=no'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
+          PRECHECK_BUNDLED_GEMS: 'no'
+          LAUNCHABLE_STDOUT: ${{ steps.launchable.outputs.stdout_report_path }}
+          LAUNCHABLE_STDERR: ${{ steps.launchable.outputs.stderr_report_path }}
+
       - name: make skipped tests
         run: |
-          make -s test-all TESTS=`echo "$TESTS" | sed 's| |$$/ -n/|g;s|^|-n/|;s|$|$$/|'`
+          make -s test-all TESTS="${TESTS//-n!\//-n/}"
         env:
-          GNUMAKEFLAGS: ""
-          RUBY_TESTOPTS: "-v --tty=no"
-          TESTS: ${{ matrix.skipped_tests }}
-          PRECHECK_BUNDLED_GEMS: "no"
-        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests != '' }}
+          GNUMAKEFLAGS: ''
+          RUBY_TESTOPTS: '-v --tty=no'
+          PRECHECK_BUNDLED_GEMS: 'no'
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
         continue-on-error: ${{ matrix.continue-on-skipped_tests || false }}
-      - uses: k0kubun/action-slack@v2.0.0
+
+      - name: CAPI extensions
+        uses: ./.github/actions/capiext
         with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ matrix.os }} / ${{ matrix.test_task }}${{ matrix.configure }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
+          builddir: build
         env:
+          RUBY_TESTOPTS: '-v --tty=no'
+        if: ${{ contains(matrix.extra_checks, 'capi') }}
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.os }} / ${{ matrix.test_task }}
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ failure() }}
+
+      - name: Resolve job ID
+        id: job_id
+        uses: actions/github-script@main
+        env:
+          matrix: ${{ toJson(matrix) }}
+        with:
+          script: |
+            const { data: workflow_run } = await github.rest.actions.listJobsForWorkflowRun({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              run_id: context.runId
+            });
+            const matrix = JSON.parse(process.env.matrix);
+            const job_name = `${context.job}${matrix ? ` (${Object.values(matrix).join(", ")})` : ""}`;
+            return workflow_run.jobs.find((job) => job.name === job_name).id;
+
+  result:
+    if: ${{ always() }}
+    name: ${{ github.workflow }} result
+    runs-on: macos-latest
+    needs: [make]
+    steps:
+      - run: exit 1
+        working-directory:
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
 
 defaults:
   run:
diff --git a/.github/workflows/mingw.yml b/.github/workflows/mingw.yml
index 020295baa1..5c639ad48b 100644
--- a/.github/workflows/mingw.yml
+++ b/.github/workflows/mingw.yml
@@ -3,168 +3,241 @@ on:
   push:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   pull_request:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions:
+  contents: read
+
 # Notes:
 # Actions console encoding causes issues, see test-all & test-spec steps
 #
 jobs:
   make:
-    runs-on: windows-2022
+    runs-on: windows-${{ matrix.os }}
+
     name: ${{ github.workflow }} (${{ matrix.msystem }})
+
     env:
       MSYSTEM: ${{ matrix.msystem }}
-      MSYS2_ARCH: x86_64
-      CHOST: "x86_64-w64-mingw32"
-      CFLAGS:   "-march=x86-64 -mtune=generic -O3 -pipe -fstack-protector-strong"
-      CXXFLAGS: "-march=x86-64 -mtune=generic -O3 -pipe"
-      CPPFLAGS: "-D_FORTIFY_SOURCE=2 -D__USE_MINGW_ANSI_STDIO=1 -DFD_SETSIZE=2048"
-      LDFLAGS:  "-pipe -fstack-protector-strong"
-      UPDATE_UNICODE: "UNICODE_FILES=. UNICODE_PROPERTY_FILES=. UNICODE_AUXILIARY_FILES=. UNICODE_EMOJI_FILES=."
-      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
+      MSYS2_ARCH: >-
+        ${{
+        contains(matrix.msystem, 'arm64') && 'aarch64' ||
+        contains(matrix.msystem, '64') && 'x86_64' || 'i686'
+        }}
+      MINGW_PACKAGE_PREFIX: >-
+        mingw-w${{
+        endsWith(matrix.msystem, '64') && '64' || '32'
+        }}-${{
+        startsWith(matrix.msystem, 'clang') && 'clang' ||
+        startsWith(matrix.msystem, 'ucrt') && 'ucrt' ||
+        'mingw'
+        }}-${{
+        contains(matrix.msystem, 'arm64') && 'aarch64' ||
+        endsWith(matrix.msystem, '64') && 'x86_64' || 'i686'
+        }}
+      CFLAGS: '-mtune=generic -O3 -pipe'
+      CXXFLAGS: '-mtune=generic -O3 -pipe'
+      CPPFLAGS: '-D_FORTIFY_SOURCE=2 -D__USE_MINGW_ANSI_STDIO=1 -DFD_SETSIZE=2048'
+      LDFLAGS: '-pipe'
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+
     strategy:
       matrix:
         include:
-          - msystem: "MINGW64"
-            base_ruby: 2.6
-            test_task: "check"
-            test-all-opts: "--name=!/TestObjSpace#test_reachable_objects_during_iteration/"
-          - msystem: "UCRT64"
-            base_ruby: head
-            test_task: "check"
-            test-all-opts: "--name=!/TestObjSpace#test_reachable_objects_during_iteration/"
+          # To mitigate flakiness of MinGW CI, we test only one runtime that newer MSYS2 uses.
+          # Ruby 3.2 is the first Windows Ruby to use OpenSSL 3.x
+          - msystem: 'UCRT64'
+            os: 2022
+            test_task: 'check'
+            test-all-opts: '--name=!/TestObjSpace#test_reachable_objects_during_iteration/'
+          - msystem: 'CLANGARM64'
+            os: 11-arm
+            test_task: 'check'
       fail-fast: false
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
     steps:
-      - run: mkdir build
-        working-directory:
-      - name: git config
-        run: |
-          git config --global core.autocrlf false
-          git config --global core.eol lf
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v3
-        with:
-          path: src
-      - uses: actions/cache@v3
+      - uses: msys2/setup-msys2@4f806de0a5a7294ffabaff804b38a9b435a73bda # v2.30.0
+        id: msys2
         with:
-          path: src/.downloaded-cache
-          key: downloaded-cache
-      - name: Set up Ruby & MSYS2
-        uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: ${{ matrix.base_ruby }}
-      - name: set env
+          msystem: ${{ matrix.msystem }}
+          update: true
+          install: >-
+            git
+            make
+            ruby
+            autoconf
+            ${{ env.MINGW_PACKAGE_PREFIX }}-gcc
+            ${{ env.MINGW_PACKAGE_PREFIX }}-ragel
+            ${{ env.MINGW_PACKAGE_PREFIX }}-openssl
+            ${{ env.MINGW_PACKAGE_PREFIX }}-libyaml
+            ${{ env.MINGW_PACKAGE_PREFIX }}-libffi
+
+      - name: Set up env
+        id: setup-env
+        working-directory:
         run: |
-          echo "GNUMAKEFLAGS=-j$((2 * NUMBER_OF_PROCESSORS))" >> $GITHUB_ENV
+          $msys2 = ${env:MSYS2_LOCATION}
+          $msystem = ${env:MSYSTEM}.ToLower()
+          echo $msys2\usr\bin $msys2\$msystem\bin |
+            Tee-Object ${env:GITHUB_PATH} -Append -Encoding utf-8
+
+          # Use the fast device for the temporary directory.
+          # %TEMP% is inconsistent with %TMP% and test-all expects they are consistent.
+          # https://github.com/actions/virtual-environments/issues/712#issuecomment-613004302
+          $tmp = ${env:RUNNER_TEMP}
+          echo HOME=$home TMP=$tmp TEMP=$tmp TMPDIR=$tmp |
+            Tee-Object ${env:GITHUB_ENV} -Append -Encoding utf-8
+        shell: pwsh             # cmd.exe does not strip spaces before `|`.
+        env:
+          MSYS2_LOCATION: ${{ steps.msys2.outputs.msys2-location }}
+          MSYSTEM: ${{ matrix.msystem }}
 
-      - name: where check
-        run: |
-          # show where
-          mv /c/Windows/System32/libcrypto-1_1-x64.dll /c/Windows/System32/libcrypto-1_1-x64.dll_
-          mv /c/Windows/System32/libssl-1_1-x64.dll    /c/Windows/System32/libssl-1_1-x64.dll_
-          result=true
-          for e in gcc.exe ragel.exe make.exe bison.exe libcrypto-1_1-x64.dll libssl-1_1-x64.dll; do
-            echo '##['group']'$'\033[93m'$e$'\033[m'
-            where $e || result=false
-            echo '##['endgroup']'
-          done
-          $result
-
-      - name: version check
+      - name: Remove Strawberry Perl pkg-config
+        working-directory:
+        # `pkg-config.bat` included in Strawberry Perl is written in
+        # Perl and doesn't work when another msys2 `perl` precede its
+        # own `perl`.
+        #
+        # ```
+        # Can't find C:\Strawberry\perl\bin\pkg-config.bat on PATH, '.' not in PATH.
+        # ```
         run: |
-          # show version
-          result=true
-          for e in gcc ragel make bison "openssl version"; do
-            case "$e" in *" "*) ;; *) e="$e --version";; esac
-            echo '##['group']'$'\033[93m'$e$'\033[m'
-            $e || result=false
-            echo '##['endgroup']'
-          done
-          $result
-
-      - name: autogen
+          Get-Command pkg-config.bat | % { ren $_.path ($_.path + "~") }
+        shell: pwsh
+
+      - name: Misc system & package info
+        working-directory:
         run: |
-          ./autogen.sh
-        working-directory: src
+          group() { echo ::group::$'\e[94;1m'"$*"$'\e[m'; }
+          endgroup() { echo ::endgroup::; }
+
+          group Path
+          cygpath -wa / . $(type -p cygpath bash sh)
+          endgroup
+
+          I() {
+              group $1
+              run Where type -pa $1 && { [ $# -eq 1 ] || run Version "$@"; } ||
+                  failed+=($1)
+              endgroup
+          }
+          run() { local w m=$1; shift; w="$("$@")" && show "$m" && indent "$w"; }
+          indent() { [ -z "$1" ] || echo "$1" | /bin/sed '/^$/!s/^/  /'; }
+          show() { echo $'\e[96m'"$*"$'\e[m'; }
+
+          failed=()
+
+          I gcc.exe --version
+          I ragel.exe --version
+          I make.exe --version
+          I openssl.exe version
+          I libcrypto-3-x64.dll
+          I libssl-3-x64.dll
+
+          group Packages
+          pacman -Qs $MINGW_PACKAGE_PREFIX-* | /bin/sed -n "s,local/$MINGW_PACKAGE_PREFIX-,,p"
+          endgroup
+
+          [ ${#failed[@]} -eq 0 ]
+        shell: sh
+
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          # Set fetch-depth: 10 so that Launchable can receive commits information.
+          fetch-depth: 10
 
       - name: configure
         run: >
           ../src/configure --disable-install-doc --prefix=/.
           --build=$CHOST --host=$CHOST --target=$CHOST
-
-      - name: update
-        run: |
-          make incs
-
-      - name: download gems
-        run: |
-          make update-gems
+        shell: sh
+        env:
+          CHOST: ${{ env.MSYS2_ARCH }}-w64-mingw32
 
       - name: make all
         timeout-minutes: 30
-        run: |
-          make
-
-      - run: make leaked-globals
+        run: make -j4
 
       - name: make install
-        run: |
-          make DESTDIR=../install install-nodoc
+        run: make DESTDIR=../install install-nodoc
+
+      - name: Set up Launchable
+        uses: ./.github/actions/launchable/setup
+        with:
+          os: windows-2022
+          launchable-token: ${{ secrets.LAUNCHABLE_TOKEN }}
+          builddir: build
+          srcdir: src
+          test-tasks: '["test", "test-all", "test-spec"]'
+        continue-on-error: true
+        timeout-minutes: 3
 
       - name: test
-        timeout-minutes: 5
-        run: |
-          make test
-        if: ${{matrix.test_task == 'check' || matrix.test_task == 'test'}}
+        timeout-minutes: 30
+        run: make test test-tool
+        env:
+          GNUMAKEFLAGS: ''
+          RUBY_TESTOPTS: '-v --tty=no'
+        if: ${{ matrix.test_task == 'check' || matrix.test_task == 'test' }}
 
       - name: test-all
         timeout-minutes: 45
         run: |
-          # Actions uses UTF8, causes test failures, similar to normal OS setup
-          chcp.com 437
           make ${{ StartsWith(matrix.test_task, 'test/') && matrix.test_task || 'test-all' }}
         env:
           RUBY_TESTOPTS: >-
-            --retry --job-status=normal --show-skip --timeout-scale=1.5
+            --retry --job-status=normal --show-skip --timeout-scale=1.5 -j4
             ${{ matrix.test-all-opts }}
+            ${{ env.TESTS }}
           BUNDLER_VERSION:
-        if: ${{matrix.test_task == 'check' || matrix.test_task == 'test-all' || StartsWith(matrix.test_task, 'test/')}}
+        if: ${{ matrix.test_task == 'check' || matrix.test_task == 'test-all' || StartsWith(matrix.test_task, 'test/') }}
 
       - name: test-spec
         timeout-minutes: 10
         run: |
           make ${{ StartsWith(matrix.test_task, 'spec/') && matrix.test_task || 'test-spec' }}
-        if: ${{matrix.test_task == 'check' || matrix.test_task == 'test-spec' || StartsWith(matrix.test_task, 'spec/')}}
+        if: ${{ matrix.test_task == 'check' || matrix.test_task == 'test-spec' || StartsWith(matrix.test_task, 'spec/') }}
 
-      - uses: k0kubun/action-slack@v2.0.0
+      - uses: ./src/.github/actions/slack
         with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ github.workflow }} ${{ matrix.msystem }} / ${{ matrix.test_task }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
-        env:
+          label: ${{ matrix.msystem }} / ${{ matrix.test_task }}
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ failure() }}
 
 defaults:
   run:
     working-directory: build
-    shell: sh
+    shell: cmd
diff --git a/.github/workflows/mjit-bindgen.yml b/.github/workflows/mjit-bindgen.yml
deleted file mode 100644
index 33a1650f92..0000000000
--- a/.github/workflows/mjit-bindgen.yml
+++ /dev/null
@@ -1,101 +0,0 @@
-name: MJIT bindgen
-on:
-  push:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
-  pull_request:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
-
-concurrency:
-  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
-  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
-
-jobs:
-  make:
-    strategy:
-      matrix:
-        include:
-          - task: mjit-bindgen
-            configure: '--enable-yjit=dev_nodebug'
-          - task: mjit-bindgen
-            arch: i686
-      fail-fast: false
-    env:
-      SETARCH: ${{ matrix.arch && format('setarch {0}', matrix.arch) }}
-    runs-on: ubuntu-20.04
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
-    steps:
-      - run: mkdir build
-        working-directory:
-      - name: Set ENV
-        run: |
-          echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
-      - name: Install libraries
-        env:
-          arch: ${{ matrix.arch }}
-        run: |
-          set -x
-          arch=${arch:+:${arch/i[3-6]86/i386}}
-          ${arch:+sudo dpkg --add-architecture ${arch#:}}
-          sudo apt-get update -q || :
-          sudo apt-get install --no-install-recommends -q -y \
-          ${arch:+cross}build-essential${arch/:/-} \
-          libssl-dev${arch} libyaml-dev${arch} libreadline6-dev${arch} \
-          zlib1g-dev${arch} libncurses5-dev${arch} libffi-dev${arch} \
-          libclang1-10${arch} \
-          bison autoconf ruby
-          sudo apt-get install -q -y pkg-config${arch} || :
-      - name: git config
-        run: |
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v3
-        with:
-          path: src
-      - uses: actions/cache@v3
-        with:
-          path: src/.downloaded-cache
-          key: downloaded-cache
-      - name: Fixed world writable dirs
-        run: |
-          chmod -v go-w $HOME $HOME/.config
-          sudo chmod -R go-w /usr/share
-          sudo bash -c 'IFS=:; for d in '"$PATH"'; do chmod -v go-w $d; done' || :
-      - run: ./autogen.sh
-        working-directory: src
-      - name: Run configure
-        env:
-          arch: ${{ matrix.arch }}
-        run: >-
-          $SETARCH ../src/configure -C --disable-install-doc --prefix=$(pwd)/install ${{ matrix.configure }}
-          ${arch:+--target=$arch-$OSTYPE --host=$arch-$OSTYPE}
-      - run: $SETARCH make incs
-      - run: $SETARCH make
-      - run: $SETARCH make install
-      - run: $SETARCH make ${{ matrix.task }}
-      - run: git diff --exit-code
-        working-directory: src
-      - uses: k0kubun/action-slack@v2.0.0
-        with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ matrix.os }} / ${{ matrix.test_task }}${{ matrix.configure }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
-        env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
-
-defaults:
-  run:
-    working-directory: build
diff --git a/.github/workflows/mjit.yml b/.github/workflows/mjit.yml
deleted file mode 100644
index b5065288c7..0000000000
--- a/.github/workflows/mjit.yml
+++ /dev/null
@@ -1,99 +0,0 @@
-name: MJIT
-on:
-  push:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
-  pull_request:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
-
-concurrency:
-  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
-  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
-
-jobs:
-  make:
-    strategy:
-      matrix:
-        test_task: [ "check" ] # to make job names consistent
-        jit_opts: [ "--mjit", "--mjit-wait" ]
-      fail-fast: false
-    runs-on: ubuntu-latest
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
-    env:
-      TESTOPTS: '-q --tty=no'
-      RUN_OPTS: '--disable-gems ${{ matrix.jit_opts }} --mjit-debug=-ggdb3'
-      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
-    steps:
-      - run: mkdir build
-        working-directory:
-      - name: Install libraries
-        run: |
-          set -x
-          sudo apt-get update -q || :
-          sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev bison autoconf ruby
-      - name: git config
-        run: |
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v3
-        with:
-          path: src
-      - uses: actions/cache@v3
-        with:
-          path: src/.downloaded-cache
-          key: downloaded-cache
-      - name: Fixed world writable dirs
-        run: |
-          chmod -v go-w $HOME $HOME/.config
-          sudo chmod -R go-w /usr/share
-          sudo bash -c 'IFS=:; for d in '"$PATH"'; do chmod -v go-w $d; done' || :
-      - name: Set ENV
-        run: |
-          echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
-      - run: ./autogen.sh
-        working-directory: src
-      - name: Run configure
-        run: ../src/configure -C --disable-install-doc cppflags=-DVM_CHECK_MODE
-      - run: make incs
-      - run: make
-      - run: sudo make -s install
-      - run: sudo apt-get install gdb # used by test / test-all failure
-      - name: Run test
-        run: |
-          ulimit -c unlimited
-          make -s test RUN_OPTS="$RUN_OPTS"
-        timeout-minutes: 60
-      - name: Run test-all
-        run: |
-          ulimit -c unlimited
-          make -s test-all RUN_OPTS="$RUN_OPTS"
-        timeout-minutes: 60
-      - name: Run test-spec
-        run: |
-          ulimit -c unlimited
-          make -s test-spec RUN_OPTS="$RUN_OPTS"
-        timeout-minutes: 60
-      - uses: k0kubun/action-slack@v2.0.0
-        with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ github.workflow }} / ${{ matrix.test_task }} ${{ matrix.jit_opts }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
-        env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
-
-defaults:
-  run:
-    working-directory: build
diff --git a/.github/workflows/modgc.yml b/.github/workflows/modgc.yml
new file mode 100644
index 0000000000..1d14934df8
--- /dev/null
+++ b/.github/workflows/modgc.yml
@@ -0,0 +1,176 @@
+name: ModGC
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    strategy:
+      matrix:
+        gc:
+          - name: default
+          - name: mmtk
+            mmtk_build: release
+        os: [macos-latest, ubuntu-latest]
+        include:
+          - test_task: check
+      fail-fast: false
+
+    env:
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+      RUBY_DEBUG: ci
+
+    runs-on: ${{ matrix.os }}
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - name: Install libraries (macOS)
+        uses: ./.github/actions/setup/macos
+        if: ${{ contains(matrix.os, 'macos') }}
+
+      - name: Install libraries (Ubuntu)
+        uses: ./.github/actions/setup/ubuntu
+        if: ${{ contains(matrix.os, 'ubuntu') }}
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
+        with:
+          ruby-version: '3.1'
+          bundler: none
+        if: ${{ contains(matrix.os, 'ubuntu') }}
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          clean: true
+          dummy-files: false
+          # Set fetch-depth: 10 so that Launchable can receive commits information.
+          fetch-depth: 10
+
+      - name: make sure that kern.coredump=1
+        run: |
+          sysctl -n kern.coredump
+          sudo sysctl -w kern.coredump=1
+          sudo chmod -R +rwx /cores/
+        if: ${{ contains(matrix.os, 'macos') }}
+
+      - name: Delete unused SDKs
+        # To free up disk space to not run out during the run
+        run: |
+          sudo rm -rf ~/.dotnet
+          sudo rm -rf /Library/Android
+          sudo rm -rf /Library/Developer/CoreSimulator
+        continue-on-error: true
+        if: ${{ contains(matrix.os, 'macos') }}
+
+      - name: Setup Ruby GC Directory
+        run: |
+          echo "MODULAR_GC_DIR=$HOME/ruby_gc" >> $GITHUB_ENV
+
+      - name: Run configure
+        env:
+          arch: ${{ matrix.arch }}
+        run: >-
+          $SETARCH ../src/configure -C --disable-install-doc --with-modular-gc=${{ env.MODULAR_GC_DIR }}
+          ${arch:+--target=$arch-$OSTYPE --host=$arch-$OSTYPE}
+
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+      - name: Set MMTk environment variables
+        run: |
+          echo 'EXCLUDES=../src/test/.excludes-mmtk' >> $GITHUB_ENV
+          echo 'MSPECOPT=-B../src/spec/mmtk.mspec' >> $GITHUB_ENV
+        if: ${{ matrix.gc.name == 'mmtk' }}
+
+      - run: $SETARCH make
+
+      - name: Build Modular  GC
+        run: |
+          echo "RUBY_GC_LIBRARY=${{ matrix.gc.name }}" >> $GITHUB_ENV
+          make install-modular-gc MODULAR_GC=${{ matrix.gc.name }} MMTK_BUILD=${{ matrix.gc.mmtk_build }}
+          make distclean-modular-gc MODULAR_GC=${{ matrix.gc.name }}
+
+      - run: $SETARCH make hello
+
+      - name: Set test options for skipped tests
+        run: |
+          set -x
+          TESTS="$(echo "${{ matrix.skipped_tests }}" | sed 's| |$$/ -n!/|g;s|^|-n!/|;s|$|$$/|')"
+          echo "TESTS=${TESTS}" >> $GITHUB_ENV
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
+
+      - name: Set up Launchable
+        id: launchable
+        uses: ./.github/actions/launchable/setup
+        with:
+          os: ${{ matrix.os || 'ubuntu-22.04' }}
+          test-opts: ${{ matrix.configure }}
+          launchable-token: ${{ secrets.LAUNCHABLE_TOKEN }}
+          builddir: build
+          srcdir: src
+        continue-on-error: true
+        timeout-minutes: 3
+
+      - name: make ${{ matrix.test_task }}
+        run: |
+          test -n "${LAUNCHABLE_STDOUT}" && exec 1> >(tee "${LAUNCHABLE_STDOUT}")
+          test -n "${LAUNCHABLE_STDERR}" && exec 2> >(tee "${LAUNCHABLE_STDERR}")
+
+          $SETARCH make -s ${{ matrix.test_task }} \
+            ${TESTS:+TESTS="$TESTS"} \
+            ${{ !contains(matrix.test_task, 'bundle') && 'RUBYOPT=-w' || '' }}
+        timeout-minutes: ${{ matrix.gc.timeout || 40 }}
+        env:
+          RUBY_TESTOPTS: '-q --tty=no'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
+          PRECHECK_BUNDLED_GEMS: 'no'
+          LAUNCHABLE_STDOUT: ${{ steps.launchable.outputs.stdout_report_path }}
+          LAUNCHABLE_STDERR: ${{ steps.launchable.outputs.stderr_report_path }}
+
+      - name: make skipped tests
+        run: |
+          $SETARCH make -s test-all TESTS="${TESTS//-n!\//-n/}"
+        env:
+          GNUMAKEFLAGS: ''
+          RUBY_TESTOPTS: '-v --tty=no'
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
+        continue-on-error: ${{ matrix.continue-on-skipped_tests || false }}
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.test_task }} ${{ matrix.configure }}${{ matrix.arch }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/parse_y.yml b/.github/workflows/parse_y.yml
new file mode 100644
index 0000000000..87facc8a55
--- /dev/null
+++ b/.github/workflows/parse_y.yml
@@ -0,0 +1,100 @@
+name: parse.y
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  make:
+    strategy:
+      matrix:
+        include:
+          - test_task: check
+          - test_task: test-bundler-parallel
+          - test_task: test-bundled-gems
+      fail-fast: false
+
+    env:
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+      RUBY_DEBUG: ci
+      SETARCH: ${{ matrix.arch && format('setarch {0}', matrix.arch) }}
+
+    runs-on: ubuntu-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - uses: ./.github/actions/setup/ubuntu
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
+        with:
+          ruby-version: '3.1'
+          bundler: none
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          clean: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
+
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc cppflags=-DRUBY_DEBUG --with-parser=parse.y
+
+      - run: make
+
+      - run: make TESTRUN_SCRIPT='-renvutil -v -e "exit EnvUtil.current_parser == %[parse.y]"' run
+        env:
+          RUNOPT0: -I$(tooldir)/lib
+
+      - name: make ${{ matrix.test_task }}
+        run: make -s ${{ matrix.test_task }} RUN_OPTS="$RUN_OPTS" SPECOPTS="$SPECOPTS"
+        env:
+          RUBY_TESTOPTS: ${{ matrix.testopts }}
+          EXCLUDES: '../src/test/.excludes-parsey'
+          RUN_OPTS: ${{ matrix.run_opts || '--parser=parse.y' }}
+          SPECOPTS: ${{ matrix.specopts || '-T --parser=parse.y' }}
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.run_opts }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/post_push.yml b/.github/workflows/post_push.yml
new file mode 100644
index 0000000000..318444c0a2
--- /dev/null
+++ b/.github/workflows/post_push.yml
@@ -0,0 +1,85 @@
+name: Post-push
+on:
+  push:
+    branches:
+      - master
+      - 'ruby_*_*'
+jobs:
+  hooks:
+    name: Post-push hooks
+    runs-on: ubuntu-latest
+    if: ${{ github.repository == 'ruby/ruby' }}
+    steps:
+      - name: Sync git.ruby-lang.org
+        run: |
+          mkdir -p ~/.ssh
+          (umask 066; printenv RUBY_GIT_SYNC_PRIVATE_KEY > ~/.ssh/id_ed25519)
+          ssh-keyscan -t ed25519 git.ruby-lang.org >> ~/.ssh/known_hosts
+          ssh -i ~/.ssh/id_ed25519 git-sync@git.ruby-lang.org "sudo -u git /home/git/git.ruby-lang.org/bin/update-ruby.sh $GITHUB_REF"
+        env:
+          GITHUB_REF: ${{ github.ref }}
+          RUBY_GIT_SYNC_PRIVATE_KEY: ${{ secrets.RUBY_GIT_SYNC_PRIVATE_KEY }}
+        if: ${{ github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/heads/ruby_') }}
+
+      - name: Fetch changesets on bugs.ruby-lang.org
+        run: |
+          curl "https://bugs.ruby-lang.org/sys/fetch_changesets?key=${REDMINE_SYS_API_KEY}" -s --fail-with-body -w '* status: %{http_code}\n'
+        env:
+          REDMINE_SYS_API_KEY: ${{ secrets.REDMINE_SYS_API_KEY }}
+        if: ${{ github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/heads/ruby_') }}
+
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          fetch-depth: 500 # for notify-slack-commits
+          token: ${{ secrets.MATZBOT_AUTO_UPDATE_TOKEN }}
+
+      - name: Notify commit to Slack
+        run: ruby tool/notify-slack-commits.rb "$GITHUB_OLD_SHA" "$GITHUB_NEW_SHA" refs/heads/master
+        env:
+          GITHUB_OLD_SHA: ${{ github.event.before }}
+          GITHUB_NEW_SHA: ${{ github.event.after }}
+          SLACK_WEBHOOK_URL_ALERTS: ${{ secrets.SLACK_WEBHOOK_URL_ALERTS }}
+          SLACK_WEBHOOK_URL_COMMITS: ${{ secrets.SLACK_WEBHOOK_URL_COMMITS }}
+          SLACK_WEBHOOK_URL_RUBY_JP: ${{ secrets.SLACK_WEBHOOK_URL_RUBY_JP }}
+        if: ${{ github.ref == 'refs/heads/master' }}
+
+      - name: Notify commit to ruby-cvs
+        run: |
+          SENDMAIL="ssh -i ${HOME}/.ssh/id_ed25519 git-sync@git.ruby-lang.org /usr/sbin/sendmail" \
+            ruby tool/commit-email.rb . ruby-cvs@g.ruby-lang.org \
+            "$GITHUB_OLD_SHA" "$GITHUB_NEW_SHA" "$GITHUB_REF" \
+            --viewer-uri "https://github.com/ruby/ruby/commit/" \
+            --error-to cvs-admin@ruby-lang.org
+        env:
+          GITHUB_OLD_SHA: ${{ github.event.before }}
+          GITHUB_NEW_SHA: ${{ github.event.after }}
+          GITHUB_REF: ${{ github.ref }}
+        if: ${{ github.ref == 'refs/heads/master' || startsWith(github.ref, 'refs/heads/ruby_') }}
+
+      - name: Auto-correct code styles
+        run: |
+          set -x
+          ruby tool/auto-style.rb "$GITHUB_OLD_SHA" "$GITHUB_NEW_SHA" refs/heads/master
+        env:
+          GITHUB_OLD_SHA: ${{ github.event.before }}
+          GITHUB_NEW_SHA: ${{ github.event.after }}
+          GIT_AUTHOR_NAME: git
+          GIT_COMMITTER_NAME: git
+          EMAIL: svn-admin@ruby-lang.org
+        if: ${{ github.ref == 'refs/heads/master' }}
+
+      - name: Push PR notes to GitHub
+        run: ruby tool/notes-github-pr.rb "$(pwd)/.git" "$GITHUB_OLD_SHA" "$GITHUB_NEW_SHA" refs/heads/master
+        env:
+          GITHUB_OLD_SHA: ${{ github.event.before }}
+          GITHUB_NEW_SHA: ${{ github.event.after }}
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GIT_AUTHOR_NAME: git
+          GIT_COMMITTER_NAME: git
+          EMAIL: svn-admin@ruby-lang.org
+        if: ${{ github.ref == 'refs/heads/master' }}
+
+      - uses: ./.github/actions/slack
+        with:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
diff --git a/.github/workflows/pr-playground.yml b/.github/workflows/pr-playground.yml
new file mode 100644
index 0000000000..f3c0556429
--- /dev/null
+++ b/.github/workflows/pr-playground.yml
@@ -0,0 +1,127 @@
+name: Post Playground link to PR
+on:
+  pull_request_target:
+    types: [labeled]
+  workflow_run:
+    workflows: ["WebAssembly"]
+    types: [completed]
+
+jobs:
+  post-summary:
+    name: Post Playground link
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    # Post a comment only if the PR status check is passed and the PR is labeled with `Playground`.
+    # Triggered twice: when the PR is labeled and when PR build is passed.
+    if: >-
+      ${{ false
+      || (true
+        && github.event_name == 'pull_request_target'
+        && contains(github.event.pull_request.labels.*.name, 'Playground'))
+      || (true
+        && github.event_name == 'workflow_run'
+        && github.event.workflow_run.conclusion == 'success'
+        && github.event.workflow_run.event == 'pull_request')
+      }}
+    steps:
+      - uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const fs = require('fs/promises');
+
+            const buildWorkflowPath = '.github/workflows/wasm.yml';
+            const findSuccessfuBuildRun = async (pr) => {
+              const opts = github.rest.actions.listWorkflowRunsForRepo.endpoint.merge({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                status: 'success',
+                branch: pr.head.ref,
+              });
+              const runs = await github.paginate(opts);
+              const buildRun = runs.find(run => run.path == buildWorkflowPath);
+              return buildRun;
+            }
+
+            const postComment = async (body, pr) => {
+              const { data: comments } = await github.rest.issues.listComments({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: pr.number,
+              });
+
+              const commentOpts = { owner: context.repo.owner, repo: context.repo.repo, body: comment };
+
+              const existingComment = comments.find(comment => comment.body.startsWith(magicComment));
+              if (existingComment) {
+                core.info(`Updating existing comment: ${existingComment.html_url}`);
+                await github.rest.issues.updateComment({
+                  ...commentOpts, comment_id: existingComment.id
+                });
+              } else {
+                await github.rest.issues.createComment({
+                  ...commentOpts, issue_number: pr.number
+                });
+              }
+            }
+
+            const derivePRNumber = async () => {
+              if (context.payload.pull_request) {
+                return context.payload.pull_request.number;
+              }
+              // Workaround for https://github.com/orgs/community/discussions/25220
+
+              const { data: { artifacts } } = await github.rest.actions.listWorkflowRunArtifacts({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                run_id: context.payload.workflow_run.id,
+              });
+              const artifact = artifacts.find(artifact => artifact.name == 'github-pr-info');
+              if (!artifact) {
+                throw new Error('Cannot find github-pr-info.txt artifact');
+              }
+
+              const { data } = await github.rest.actions.downloadArtifact({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                artifact_id: artifact.id,
+                archive_format: 'zip',
+              });
+
+              await fs.writeFile('pr-info.zip', Buffer.from(data));
+              await exec.exec('unzip', ['pr-info.zip']);
+              return await fs.readFile('github-pr-info.txt', 'utf8');
+            }
+
+            const prNumber = await derivePRNumber();
+
+            const { data: pr } = await github.rest.pulls.get({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              pull_number: prNumber,
+            });
+
+            core.info(`Checking if the PR ${prNumber} is labeled with Playground...`);
+            if (!pr.labels.some(label => label.name == 'Playground')) {
+              core.info(`The PR is not labeled with Playground.`);
+              return;
+            }
+
+            core.info(`Checking if the build is successful for ${pr.head.ref} in ${pr.head.repo.owner.login}/${pr.head.repo.name}...`);
+            const buildRun = await findSuccessfuBuildRun(pr);
+            if (!buildRun) {
+              core.info(`No successful build run found for ${buildWorkflowPath} on ${pr.head.ref} yet.`);
+              return;
+            }
+            core.info(`Found a successful build run: ${buildRun.html_url}`);
+
+            const runLink = `${process.env.GITHUB_SERVER_URL}/${process.env.GITHUB_REPOSITORY}/actions/runs/${process.env.GITHUB_RUN_ID}`;
+            const magicComment = `<!-- AUTO-GENERATED-COMMENT-PR-PLAYGROUND -->`;
+            const comment = `${magicComment}
+            **Try on Playground**: https://ruby.github.io/play-ruby?run=${buildRun.id}
+            This is an automated comment by [\`pr-playground.yml\`](${runLink}) workflow.
+            `;
+            core.info(`Comment: ${comment}`);
+            await postComment(comment, pr);
+
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
new file mode 100644
index 0000000000..3caeee9a3b
--- /dev/null
+++ b/.github/workflows/publish.yml
@@ -0,0 +1,107 @@
+name: Publish Ruby packages
+
+on:
+  repository_dispatch:
+    types:
+      - release
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'Version of the Ruby package to release'
+        required: true
+        default: '3.3.4'
+
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6.0.1
+
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 3.3.4
+
+      - name: Store Ruby version
+        run: |
+          echo "RUBY_VERSION=${{ github.event.client_payload.version || github.event.inputs.version }}" >> $GITHUB_ENV
+
+      - name: Store ABI version
+        run: echo "ABI_VERSION=$(echo ${{ env.RUBY_VERSION }} | cut -d '.' -f 1-2)" >> $GITHUB_ENV
+
+      - name: Copy draft package `/tmp` to `/pub` directory
+        run: tool/release.sh ${{ env.RUBY_VERSION }}
+        env:
+          AWS_ACCESS_KEY_ID: ${{ secrets.FTP_R_L_O_AWS_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ secrets.FTP_R_L_O_AWS_SECRET_ACCESS_KEY }}
+          AWS_DEFAULT_REGION: us-west-2
+
+      - name: Purge URLs of release package
+        run: |
+          curl -X POST \
+            -H "Fastly-Key: ${{ secrets.FASTLY_PURGE_TOKEN }}" \
+            https://api.fastly.com/purge/cache.ruby-lang.org/pub/ruby/${{ env.ABI_VERSION }}/ruby-${{ env.RUBY_VERSION }}.tar.gz
+          curl -X POST \
+            -H "Fastly-Key: ${{ secrets.FASTLY_PURGE_TOKEN }}" \
+            https://api.fastly.com/purge/cache.ruby-lang.org/pub/ruby/${{ env.ABI_VERSION }}/ruby-${{ env.RUBY_VERSION }}.tar.xz
+          curl -X POST \
+            -H "Fastly-Key: ${{ secrets.FASTLY_PURGE_TOKEN }}" \
+            https://api.fastly.com/purge/cache.ruby-lang.org/pub/ruby/${{ env.ABI_VERSION }}/ruby-${{ env.RUBY_VERSION }}.zip
+
+      - name: Create a release on GitHub
+        run: |
+          RELEASE_TAG=$(ruby tool/ruby-version.rb tag "${{ env.RUBY_VERSION }}")
+          echo $RELEASE_TAG
+          PREVIOUS_RELEASE_TAG=$(ruby tool/ruby-version.rb previous-tag "${{ env.RUBY_VERSION }}")
+          echo $PREVIOUS_RELEASE_TAG
+          tool/gen-github-release.rb $PREVIOUS_RELEASE_TAG $RELEASE_TAG --no-dry-run
+        env:
+          GITHUB_TOKEN: ${{ secrets.MATZBOT_AUTO_UPDATE_TOKEN }}
+
+      - name: Update versions index
+        run: |
+          curl -L -X POST \
+            -H "Authorization: Bearer ${{ secrets.MATZBOT_GITHUB_WORKFLOW_TOKEN }}" \
+            -H "Accept: application/vnd.github+json" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            https://api.github.com/repos/ruby/actions/dispatches \
+            -d '{"event_type": "update_index"}'
+
+      - name: Build and push Docker images
+        run: |
+          curl -L -X POST \
+            -H "Authorization: Bearer ${{ secrets.MATZBOT_GITHUB_WORKFLOW_TOKEN }}" \
+            -H "Accept: application/vnd.github+json" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            https://api.github.com/repos/ruby/docker-images/actions/workflows/build.yml/dispatches \
+            -d '{"ref": "master", "inputs": {"ruby_version": "${{ env.RUBY_VERSION }}"}}'
+
+      - name: Build snapcraft packages
+        run: |
+          curl -L -X POST \
+            -H "Authorization: Bearer ${{ secrets.MATZBOT_GITHUB_WORKFLOW_TOKEN }}" \
+            -H "Accept: application/vnd.github+json" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            https://api.github.com/repos/ruby/snap.ruby/dispatches \
+            -d '{"event_type": "build", "client_payload": {"ruby_version": "${{ env.RUBY_VERSION }}"}}'
+
+      - name: Store the latest LTS version of OpenSSL
+        run: |
+          echo "OPENSSL_VERSION=`curl -s https://api.github.com/repos/openssl/openssl/releases | jq -r '.[].tag_name | select(startswith("openssl-3.0"))' | sort -Vr | head -n1 | cut -d'-' -f2`" >> $GITHUB_ENV
+
+      - name: Update ruby-build definition
+        run: |
+          curl -L -X POST \
+            -H "Authorization: Bearer ${{ secrets.RUBY_BUILD_WORKFLOW_TOKEN }}" \
+            -H "Accept: application/vnd.github+json" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            https://api.github.com/repos/rbenv/ruby-build/dispatches \
+            -d '{"event_type": "update-ruby", "client_payload": {"ruby_version": "${{ env.RUBY_VERSION }}", "openssl_version": "${{ env.OPENSSL_VERSION }}"}}'
+
+      - name: Update all-ruby definition
+        run: |
+          curl -L -X POST \
+            -H "Authorization: Bearer ${{ secrets.MATZBOT_GITHUB_WORKFLOW_TOKEN }}" \
+            -H "Accept: application/vnd.github+json" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            https://api.github.com/repos/ruby/all-ruby/dispatches \
+            -d '{"event_type": "update"}'
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 0000000000..5d4474d978
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,18 @@
+name: Start release workflow
+on:
+  push:
+    tags:
+      - '*'
+
+jobs:
+  notify:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Build release package
+        run: |
+          curl -L -X POST \
+            -H "Authorization: Bearer ${{ secrets.MATZBOT_GITHUB_WORKFLOW_TOKEN }}" \
+            -H "Accept: application/vnd.github+json" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            https://api.github.com/repos/ruby/actions/dispatches \
+            -d '{"event_type": "${{ github.ref }}"}'
diff --git a/.github/workflows/rust-warnings.yml b/.github/workflows/rust-warnings.yml
new file mode 100644
index 0000000000..a2e3208e52
--- /dev/null
+++ b/.github/workflows/rust-warnings.yml
@@ -0,0 +1,60 @@
+# Surface Rust warnings on PRs that touch any Rust code.
+# Not a required check so we never block people over new warnings
+# that might come from a new Rust version being released.
+name: Rust warnings
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+    paths:
+      - '**.rs'
+      - '!**.inc.rs'
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  rust-warnings:
+    env:
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+
+    runs-on: ubuntu-24.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - name: Install Rust
+        run: rustup default beta
+
+      - name: Rust warnings
+        shell: bash
+        run: |
+          set -eu
+          cargo check --quiet --all-features --message-format=json \
+            | jq -r 'select(.message.level | IN("warning", "error")) | .message.rendered' \
+            | tee messages.txt
+          (exit "${PIPESTATUS[0]}") && ! grep --quiet '[^[:space:]]' messages.txt
+
+      - name: "📜 `rustdoc` warnings"
+        shell: bash
+        run: |
+          set -eu
+          cargo doc --document-private-items --all --no-deps --message-format=json \
+            | jq -r 'select(.message.level | IN("warning", "error")) | .message.rendered' \
+            | tee messages.txt
+          (exit "${PIPESTATUS[0]}") && ! grep --quiet '[^[:space:]]' messages.txt
diff --git a/.github/workflows/scorecards.yml b/.github/workflows/scorecards.yml
new file mode 100644
index 0000000000..c607098997
--- /dev/null
+++ b/.github/workflows/scorecards.yml
@@ -0,0 +1,78 @@
+# This workflow uses actions that are not certified by GitHub. They are provided
+# by a third-party and are governed by separate terms of service, privacy
+# policy, and support documentation.
+
+name: Scorecard supply-chain security
+on:
+  # For Branch-Protection check. Only the default branch is supported. See
+  # https://github.com/ossf/scorecard/blob/main/docs/checks.md#branch-protection
+  branch_protection_rule:
+  # To guarantee Maintained check is occasionally updated. See
+  # https://github.com/ossf/scorecard/blob/main/docs/checks.md#maintained
+  schedule:
+    - cron: '39 3 * * 5'
+  # push:
+  #   branches: [ "master" ]
+
+# Declare default permissions as read only.
+permissions: read-all
+
+jobs:
+  analysis:
+    name: Scorecard analysis
+    runs-on: ubuntu-latest
+    # `publish_results: true` only works when run from the default branch. conditional can be removed if disabled.
+    if: github.event.repository.default_branch == github.ref_name || github.event_name == 'pull_request'
+    permissions:
+      # Needed to upload the results to code-scanning dashboard.
+      security-events: write
+      # Needed to publish results and get a badge (see publish_results below).
+      id-token: write
+      # Uncomment the permissions below if installing in a private repository.
+      # contents: read
+      # actions: read
+
+    steps:
+      - name: "Checkout code"
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          persist-credentials: false
+
+      - name: "Run analysis"
+        uses: ossf/scorecard-action@4eaacf0543bb3f2c246792bd56e8cdeffafb205a # v2.4.3
+        with:
+          results_file: results.sarif
+          results_format: sarif
+          # (Optional) "write" PAT token. Uncomment the `repo_token` line below if:
+          # - you want to enable the Branch-Protection check on a *public* repository, or
+          # - you are installing Scorecard on a *private* repository
+          # To create the PAT, follow the steps in https://github.com/ossf/scorecard-action?tab=readme-ov-file#authentication-with-fine-grained-pat-optional.
+          # repo_token: ${{ secrets.SCORECARD_TOKEN }}
+
+          # Public repositories:
+          #   - Publish results to OpenSSF REST API for easy access by consumers
+          #   - Allows the repository to include the Scorecard badge.
+          #   - See https://github.com/ossf/scorecard-action#publishing-results.
+          # For private repositories:
+          #   - `publish_results` will always be set to `false`, regardless
+          #     of the value entered here.
+          publish_results: true
+
+          # (Optional) Uncomment file_mode if you have a .gitattributes with files marked export-ignore
+          # file_mode: git
+
+      # Upload the results as artifacts (optional). Commenting out will disable uploads of run results in SARIF
+      # format to the repository Actions tab.
+      - name: "Upload artifact"
+        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
+        with:
+          name: SARIF file
+          path: results.sarif
+          retention-days: 5
+
+      # Upload the results to GitHub's code scanning dashboard (optional).
+      # Commenting out will disable upload of results to your repo's Code Scanning dashboard
+      - name: "Upload to code-scanning"
+        uses: github/codeql-action/upload-sarif@v4
+        with:
+          sarif_file: results.sarif
diff --git a/.github/workflows/spec_guards.yml b/.github/workflows/spec_guards.yml
index 7bffe25bb2..cf4661555c 100644
--- a/.github/workflows/spec_guards.yml
+++ b/.github/workflows/spec_guards.yml
@@ -2,56 +2,66 @@ name: Rubyspec Version Guards Check
 
 on:
   push:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
+    paths:
+      - '.github/workflows/spec_guards.yml'
+      - 'spec/**'
+      - '!spec/*.md'
   pull_request:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
+    paths:
+      - '.github/workflows/spec_guards.yml'
+      - 'spec/**'
+      - '!spec/*.md'
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions:
+  contents: read
+
 jobs:
   rubyspec:
     name: Rubyspec
-    runs-on: ubuntu-20.04
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+
+    runs-on: ubuntu-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
     strategy:
       matrix:
         # Specs from ruby/spec should still run on all supported Ruby versions.
         # This also ensures the needed ruby_version_is guards are there, see spec/README.md.
         ruby:
-          - ruby-2.7
-          - ruby-3.1
+          - ruby-3.2
+          - ruby-3.3
+          - ruby-3.4
+          - ruby-4.0
+      fail-fast: false
 
     steps:
-      - uses: actions/checkout@v3
-      - uses: ruby/setup-ruby@v1
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
         with:
           ruby-version: ${{ matrix.ruby }}
           bundler: none
+
       - run: gem install webrick
+
       - run: ruby ../mspec/bin/mspec
         working-directory: spec/ruby
         env:
           CHECK_LEAKS: true
-      - uses: k0kubun/action-slack@v2.0.0
+
+      - uses: ./.github/actions/slack
         with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ github.workflow }} / rubyspec @ ${{ matrix.ruby }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
-        env:
+          label: ${{ matrix.ruby }}
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ failure() }}
diff --git a/.github/workflows/sync_default_gems.yml b/.github/workflows/sync_default_gems.yml
new file mode 100644
index 0000000000..9ff97d5a4e
--- /dev/null
+++ b/.github/workflows/sync_default_gems.yml
@@ -0,0 +1,77 @@
+name: Sync default gems
+
+env:
+  DEFAULT_GEM_SYNC_ENABLED: true
+
+on:
+  workflow_dispatch:
+    inputs:
+      gem:
+        required: true
+        description: 'Name of the gem to be synchronized'
+        type: string
+      before:
+        required: true
+        description: 'Gem commit SHA before sync'
+        type: string
+      after:
+        required: true
+        description: 'Gem commit SHA after sync'
+        type: string
+
+jobs:
+  sync_default_gems:
+    name: Sync default gem ${{ github.event.inputs.gem }}
+
+    permissions:
+      contents: write # for Git to git push
+
+    runs-on: ubuntu-latest
+
+    if: ${{ github.repository == 'ruby/ruby' }}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        name: Check out ruby/ruby
+        with:
+          token: ${{ github.repository == 'ruby/ruby' && secrets.MATZBOT_AUTO_UPDATE_TOKEN || secrets.GITHUB_TOKEN }}
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
+        with:
+          ruby-version: '3.4'
+          bundler: none
+
+      - name: Run tool/sync_default_gems.rb
+        id: sync
+        run: |
+          ruby_before=$(git rev-parse HEAD)
+          set -x
+          ruby tool/sync_default_gems.rb "${gem_name}" "${gem_before}..${gem_after}"
+          if [[ "$(git rev-parse HEAD)" != "$ruby_before" ]]; then
+            echo update=true >> $GITHUB_OUTPUT
+          fi
+        env:
+          gem_name: ${{ github.event.inputs.gem }}
+          gem_before: ${{ github.event.inputs.before }}
+          gem_after: ${{ github.event.inputs.after }}
+          EMAIL: svn-admin@ruby-lang.org
+          GIT_AUTHOR_NAME: git
+          GIT_COMMITTER_NAME: git
+
+      - name: Push
+        run: |
+          git pull --rebase origin ${GITHUB_REF#refs/heads/}
+          git push origin ${GITHUB_REF#refs/heads/}
+        if: ${{ steps.sync.outputs.update && env.DEFAULT_GEM_SYNC_ENABLED == 'true' }}
+        env:
+          EMAIL: svn-admin@ruby-lang.org
+          GIT_AUTHOR_NAME: git
+          GIT_COMMITTER_NAME: git
+
+      - uses: ./.github/actions/slack
+        with:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+          label: "${{ github.event.inputs.gem }} (<https://github.com/${{ github.event.inputs.gem == 'rubygems' && 'rubygems' || 'ruby' }}/${{ github.event.inputs.gem }}/compare/${{ github.event.inputs.before }}...${{ github.event.inputs.after }}|diff>)"
+          event_name: workflow_dispatch
+          extra_channel_id: C05FPKAU743 # alerts-sync
+        if: ${{ failure() }}
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 6ea8c06b93..88c19b6fe6 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -3,131 +3,266 @@ on:
   push:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   pull_request:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions:
+  contents: read
+
 jobs:
   make:
     strategy:
       matrix:
-        test_task: ["check", "test-syntax-suggest", "test-bundler-parallel", "test-bundled-gems"]
-        os:
-          - ubuntu-20.04
-        configure: ["", "cppflags=-DRUBY_DEBUG"]
+        # We enumerate every job in matrix.include to save build time
         include:
-          - test_task: "check"
-            configure: ""
+          - test_task: check
+            configure: 'cppflags=-DVM_CHECK_MODE'
+          - test_task: check
             arch: i686
-          - test_task: "check"
-            configure: "--enable-shared --enable-load-relative"
-            skipped_tests: "TestGem#test_.*_from_binstubs.*"
-            continue-on-skipped_tests: true
-          - test_task: "test-all TESTS=--repeat-count=2"
+          - test_task: check
+            configure: '--disable-yjit'
+          - test_task: check
+            configure: '--enable-shared --enable-load-relative'
+          - test_task: test-bundler-parallel
+            timeout: 50
+          - test_task: test-bundled-gems
+          - test_task: check
+            os: ubuntu-24.04
+            extra_checks: [capi]
+          # ubuntu-24.04-arm jobs don't start on ruby/ruby as of 2025-10-29
+          #- test_task: check
+          #  os: ubuntu-24.04-arm
       fail-fast: false
-    env:
-      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
+
+    env: &make-env
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
       RUBY_DEBUG: ci
-      SETARCH: ${{ matrix.arch && format('setarch {0}', matrix.arch) }}
-    runs-on: ${{ matrix.os || 'ubuntu-20.04' }}
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
-    steps:
-      - run: mkdir build
-        working-directory:
-      - name: Set ENV
-        env:
-          configure: ${{matrix.configure}}
-        run: |
-          echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
-      - name: Install libraries
-        env:
-          arch: ${{matrix.arch}}
-        run: |
-          set -x
-          arch=${arch:+:${arch/i[3-6]86/i386}}
-          ${arch:+sudo dpkg --add-architecture ${arch#:}}
-          sudo apt-get update -q || :
-          sudo apt-get install --no-install-recommends -q -y \
-          ${arch:+cross}build-essential${arch/:/-} \
-          libssl-dev${arch} libyaml-dev${arch} libreadline6-dev${arch} \
-          zlib1g-dev${arch} libncurses5-dev${arch} libffi-dev${arch} \
-          bison autoconf ruby
-          sudo apt-get install -q -y pkg-config${arch} || :
-      - name: git config
-        run: |
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v3
+
+    runs-on: ${{ matrix.os || 'ubuntu-22.04' }}
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps: &make-steps
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - uses: ./.github/actions/setup/ubuntu
         with:
-          path: src
-      - uses: actions/cache@v3
+          arch: ${{ matrix.arch }}
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
         with:
-          path: src/.downloaded-cache
-          key: downloaded-cache
-      - name: Fixed world writable dirs
-        run: |
-          chmod -v go-w $HOME $HOME/.config
-          sudo chmod -R go-w /usr/share
-          sudo bash -c 'IFS=:; for d in '"$PATH"'; do chmod -v go-w $d; done' || :
-      - run: ./autogen.sh
-        working-directory: src
+          ruby-version: '3.1'
+          bundler: none
+        if: >-
+          ${{ !endsWith(matrix.os, 'arm')
+          && !endsWith(matrix.os, 'ppc64le') && !endsWith(matrix.os, 's390x') }}
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          clean: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
+          # Set fetch-depth: 10 so that Launchable can receive commits information.
+          fetch-depth: 10
+
       - name: Run configure
         env:
-          arch: ${{matrix.arch}}
+          arch: ${{ matrix.arch }}
+          configure: ${{ matrix.configure }}
         run: >-
-          $SETARCH ../src/configure -C --disable-install-doc ${{ matrix.configure }}
+          $SETARCH ../src/configure -C --disable-install-doc ${configure:-cppflags=-DRUBY_DEBUG}
           ${arch:+--target=$arch-$OSTYPE --host=$arch-$OSTYPE}
-      - run: $SETARCH make incs
+
       - run: $SETARCH make prepare-gems
         if: ${{ matrix.test_task == 'test-bundled-gems' }}
+
       - run: $SETARCH make
-      - run: $SETARCH make leaked-globals
-        if: ${{ matrix.test_task == 'check' }}
-      - name: Create dummy files in build dir
+
+      - run: $SETARCH make hello
+
+      - name: runirb
         run: |
-          $SETARCH ./miniruby -e '(("a".."z").to_a+("A".."Z").to_a+("0".."9").to_a+%w[foo bar test zzz]).each{|basename|File.write("#{basename}.rb", "raise %(do not load #{basename}.rb)")}'
-        if: ${{ matrix.test_task == 'check' }}
+          echo IRB::VERSION | $SETARCH make runirb RUNOPT="-- -f"
+
+      - name: Set test options for skipped tests
+        run: |
+          set -x
+          TESTS="$(echo "${{ matrix.skipped_tests }}" | sed 's| |$$/ -n!/|g;s|^|-n!/|;s|$|$$/|')"
+          echo "TESTS=${TESTS}" >> $GITHUB_ENV
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
+
+      - name: Set up Launchable
+        id: launchable
+        uses: ./.github/actions/launchable/setup
+        with:
+          os: ${{ matrix.os || 'ubuntu-22.04' }}
+          test-opts: ${{ matrix.configure }}
+          launchable-token: ${{ secrets.LAUNCHABLE_TOKEN }}
+          builddir: build
+          srcdir: src
+        continue-on-error: true
+        timeout-minutes: 3
+
+      # Avoid possible test failures with the zlib applying the following patch
+      # on s390x CPU architecture.
+      # https://github.com/madler/zlib/pull/410
+      - name: Disable DFLTCC
+        run: echo "DFLTCC=0" >> $GITHUB_ENV
+        if: ${{ endsWith(matrix.os, 's390x') }}
+
       - name: make ${{ matrix.test_task }}
         run: |
-          $SETARCH make -s ${{ matrix.test_task }} ${TESTS:+TESTS=`echo "$TESTS" | sed 's| |$$/ -n!/|g;s|^|-n!/|;s|$|$$/|'`}
-        timeout-minutes: 40
+          test -n "${LAUNCHABLE_STDOUT}" && exec 1> >(tee "${LAUNCHABLE_STDOUT}")
+          test -n "${LAUNCHABLE_STDERR}" && exec 2> >(tee "${LAUNCHABLE_STDERR}")
+
+          $SETARCH make -s ${{ matrix.test_task }} \
+          ${TESTS:+TESTS="$TESTS"} \
+          ${{ !contains(matrix.test_task, 'bundle') && 'RUBYOPT=-w' || '' }}
+        timeout-minutes: ${{ matrix.timeout || 40 }}
         env:
-          RUBY_TESTOPTS: "-q --tty=no"
-          TESTS: ${{ matrix.test_task == 'check' && matrix.skipped_tests || '' }}
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ""
-          PRECHECK_BUNDLED_GEMS: "no"
+          RUBY_TESTOPTS: '-q --tty=no'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
+          PRECHECK_BUNDLED_GEMS: 'no'
+          LAUNCHABLE_STDOUT: ${{ steps.launchable.outputs.stdout_report_path }}
+          LAUNCHABLE_STDERR: ${{ steps.launchable.outputs.stderr_report_path }}
+
       - name: make skipped tests
         run: |
-          $SETARCH make -s test-all TESTS=`echo "$TESTS" | sed 's| |$$/ -n/|g;s|^|-n/|;s|$|$$/|'`
+          $SETARCH make -s test-all TESTS="${TESTS//-n!\//-n/}"
         env:
-          GNUMAKEFLAGS: ""
-          RUBY_TESTOPTS: "-v --tty=no"
-          TESTS: ${{ matrix.skipped_tests }}
-        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests != '' }}
+          GNUMAKEFLAGS: ''
+          RUBY_TESTOPTS: '-v --tty=no'
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
         continue-on-error: ${{ matrix.continue-on-skipped_tests || false }}
-      - uses: k0kubun/action-slack@v2.0.0
+
+      - name: test-pc
+        run: |
+          DESTDIR=${RUNNER_TEMP-${TMPDIR-/tmp}}/installed
+          $SETARCH make test-pc "DESTDIR=$DESTDIR"
+
+      - name: CAPI extensions
+        uses: ./.github/actions/capiext
         with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ matrix.os }} / ${{ matrix.test_task }}${{ matrix.configure }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
+          builddir: build
+          make: '$SETARCH make'
         env:
+          RUBY_TESTOPTS: '-v --tty=no'
+        if: ${{ contains(matrix.extra_checks, 'capi') }}
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.test_task }} ${{ matrix.configure }}${{ matrix.arch }}${{ matrix.os }}
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ failure() }}
+
+  make-ibm:
+    strategy:
+      matrix:
+        include:
+          - test_task: check
+            os: ubuntu-24.04-ppc64le
+          - test_task: check
+            os: ubuntu-24.04-s390x
+      fail-fast: false
+
+    env: *make-env
+
+    runs-on: ${{ matrix.os }}
+
+    if: >-
+      ${{github.repository == 'ruby/ruby'
+      && !(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps: *make-steps
+
+  # Separated from `make` job to avoid making it a required status check
+  ruby-bench:
+    strategy:
+      matrix:
+        include:
+          # Using the same setup as ZJIT jobs
+          - bench_opts: '--warmup=1 --bench=1 --excludes=lobsters'
+
+    runs-on: ubuntu-24.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - uses: ./.github/actions/setup/ubuntu
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc --prefix="$(pwd)/install"
+
+      - run: make install
+
+      - name: Checkout ruby-bench
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          repository: ruby/ruby-bench
+          path: ruby-bench
+
+      # If you want to skip failing benchmark, consider using `--excludes`.
+      # e.g. `bench_opts: '--warmup=1 --bench=1 --excludes=railsbench,lobsters'`
+      - name: Run ruby-bench
+        run: ruby run_benchmarks.rb -e "ruby::../build/install/bin/ruby" ${{ matrix.bench_opts }}
+        working-directory: ruby-bench
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ruby-bench ${{ matrix.bench_opts }} ${{ matrix.ruby_opts }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+  result:
+    if: ${{ always() }}
+    name: ${{ github.workflow }} result
+    runs-on: ubuntu-latest
+    needs: [make]
+    steps:
+      - run: exit 1
+        working-directory:
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
 
 defaults:
   run:
diff --git a/.github/workflows/wasm.yml b/.github/workflows/wasm.yml
index 553347d727..0d2a6f0545 100644
--- a/.github/workflows/wasm.yml
+++ b/.github/workflows/wasm.yml
@@ -3,60 +3,80 @@ on:
   push:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   pull_request:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions: # added using https://github.com/step-security/secure-workflows
+  contents: read
+
 jobs:
   make:
     strategy:
       matrix:
         entry:
 #         # wasmtime can't compile non-optimized Asyncified binary due to locals explosion
-#         - { name: O0-debuginfo, optflags: "-O0", debugflags: "-g", wasmoptflags: "-O1" }
-#         - { name: O1,           optflags: "-O1", debugflags: ""  , wasmoptflags: "-O1" }
-          - { name: O2,           optflags: "-O2", debugflags: ""  , wasmoptflags: "-O2" }
-#         - { name: O3,           optflags: "-O3", debugflags: ""  , wasmoptflags: "-O3" }
+#         - { name: O0-debuginfo, optflags: '-O0', debugflags: '-g', wasmoptflags: '-O1' }
+#         - { name: O1,           optflags: '-O1', debugflags: ''  , wasmoptflags: '-O1' }
+          - { name: O2, optflags: '-O2', debugflags: '', wasmoptflags: '-O2' }
+#         - { name: O3,           optflags: '-O3', debugflags: ''  , wasmoptflags: '-O3' }
 #         # -O4 is equivalent to -O3 in clang, but it's different in wasm-opt
-#         - { name: O4,           optflags: "-O3", debugflags: ""  , wasmoptflags: "-O4" }
-#         - { name: Oz,           optflags: "-Oz", debugflags: ""  , wasmoptflags: "-Oz" }
+#         - { name: O4,           optflags: '-O3', debugflags: ''  , wasmoptflags: '-O4' }
+#         - { name: Oz,           optflags: '-Oz', debugflags: ''  , wasmoptflags: '-Oz' }
       fail-fast: false
+
     env:
       RUBY_TESTOPTS: '-q --tty=no'
-      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
-      WASI_SDK_VERSION_MAJOR: 14
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+      WASI_SDK_VERSION_MAJOR: 25
       WASI_SDK_VERSION_MINOR: 0
-      BINARYEN_VERSION: 109
-      WASMTIME_VERSION: v0.33.0
-    runs-on: ubuntu-20.04
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+      BINARYEN_VERSION: 113
+      WASMTIME_VERSION: v15.0.0
+
+    runs-on: ubuntu-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
     steps:
-      - run: mkdir build
-        working-directory:
-      - name: git config
-        run: |
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - uses: ./.github/actions/setup/directories
         with:
-          path: src
+          srcdir: src
+          builddir: build
+          makeup: true
+
       - name: Install libraries
         run: |
           set -ex
           sudo apt-get update -q || :
-          sudo apt-get install --no-install-recommends -q -y ruby bison make autoconf git wget
+          sudo apt-get install --no-install-recommends -q -y ruby make autoconf git wget
 
-          wasi_sdk_deb="wasi-sdk_${WASI_SDK_VERSION_MAJOR}.${WASI_SDK_VERSION_MINOR}_amd64.deb"
+          wasi_sdk_deb="wasi-sdk-${WASI_SDK_VERSION_MAJOR}.${WASI_SDK_VERSION_MINOR}-x86_64-linux.deb"
           wget "https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-${WASI_SDK_VERSION_MAJOR}/${wasi_sdk_deb}"
           sudo dpkg -i "$wasi_sdk_deb"
           rm -f "$wasi_sdk_deb"
@@ -73,17 +93,38 @@ jobs:
           wget -O - "$binaryen_url" | tar xfz -
           sudo ln -fs "$PWD/binaryen-version_${BINARYEN_VERSION}/bin/wasm-opt" /usr/local/bin/wasm-opt
         working-directory: src
+
       - name: Set ENV
         run: |
-          echo "MAKEFLAGS=-j$((1 + $(sysctl -n hw.activecpu)))" >> $GITHUB_ENV
           echo "WASI_SDK_PATH=/opt/wasi-sdk" >> $GITHUB_ENV
-      - run: ./autogen.sh
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
+        with:
+          ruby-version: '3.1'
+          bundler: none
+
+      - name: Build baseruby
+        run: |
+          set -ex
+          mkdir ../baseruby
+          pushd ../baseruby
+          ../src/configure --prefix=$PWD/install
+          make
+          make install
+
+      - name: Download config.guess with wasi version
+        run: |
+          rm tool/config.guess tool/config.sub
+          ruby tool/downloader.rb -d tool -e gnu config.guess config.sub
         working-directory: src
+
       - name: Run configure
         run: |
           ../src/configure \
             --host wasm32-unknown-wasi \
+            --with-baseruby=$PWD/../baseruby/install/bin/ruby \
             --with-static-linked-ext \
+            --with-ext=cgi/escape,continuation,coverage,date,digest/bubblebabble,digest,digest/md5,digest/rmd160,digest/sha1,digest/sha2,etc,fcntl,json,json/generator,json/parser,objspace,pathname,rbconfig/sizeof,ripper,stringio,strscan,monitor \
             LDFLAGS=" \
               -Xlinker --stack-first \
               -Xlinker -z -Xlinker stack-size=16777216 \
@@ -94,15 +135,45 @@ jobs:
 
       # miniruby may not be built when cross-compling
       - run: make mini ruby
+
+      - run: make install DESTDIR=$PWD/../install
+      - run: tar cfz ../install.tar.gz -C ../install .
+
+      - name: Upload artifacts
+        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
+        with:
+          name: ruby-wasm-install
+          path: ${{ github.workspace }}/install.tar.gz
+      - name: Show Playground URL to try the build
+        run: |
+          echo "Try on Playground: https://ruby.github.io/play-ruby?run=$GITHUB_RUN_ID" >> $GITHUB_STEP_SUMMARY
+
       - name: Run basictest
         run: wasmtime run ./../build/miniruby --mapdir /::./ -- basictest/test.rb
         working-directory: src
+
       - name: Run bootstraptest (no thread)
         run: |
           NO_THREAD_TESTS="$(grep -L Thread -R ./bootstraptest | awk -F/ '{ print $NF }' | uniq | sed -n 's/test_\(.*\).rb/\1/p' | paste -s -d, -)"
           ruby ./bootstraptest/runner.rb --ruby="$(which wasmtime) run $PWD/../build/ruby --mapdir /::./ -- " --verbose "--sets=$NO_THREAD_TESTS"
         working-directory: src
 
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.entry.name }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+      # Workaround for https://github.com/orgs/community/discussions/25220
+      - name: Save Pull Request number
+        if: ${{ github.event_name == 'pull_request' }}
+        run: echo "${{ github.event.pull_request.number }}" >> ${{ github.workspace }}/github-pr-info.txt
+      - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
+        if: ${{ github.event_name == 'pull_request' }}
+        with:
+          name: github-pr-info
+          path: ${{ github.workspace }}/github-pr-info.txt
+
 defaults:
   run:
     working-directory: build
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index 4418c78d81..1d44a5482c 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -3,152 +3,197 @@ on:
   push:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   pull_request:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions:
+  contents: read
+
 jobs:
   make:
     strategy:
       matrix:
         include:
-          - vs: 2019
-          - vs: 2022
+          - os: 2022
+            vc: 2022
+            test_task: check
+          - os: 2025
+            vc: 2022
+            test_task: check
+          - os: 11-arm
+            test_task: 'btest test-basic test-tool' # check and test-spec are broken yet.
+            target: arm64
+          - os: 2025
+            vc: 2022
+            test_task: test-bundled-gems
       fail-fast: false
-    runs-on: windows-${{ matrix.vs < 2022 && '2019' || matrix.vs }}
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
-    name: VisualStudio ${{ matrix.vs }}
+
+    runs-on: windows-${{ matrix.os }}
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    name: Windows ${{ matrix.os }}/Visual C++ ${{ matrix.vc }} (${{ matrix.test_task }})
+
     env:
-      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
-      PATCH: C:\msys64\usr\bin\patch.exe
-      OS_VER: windows-${{ matrix.vs < 2022 && '2019' || matrix.vs }}
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+      VCPKG_DEFAULT_TRIPLET: ${{ matrix.target || 'x64' }}-windows
+
     steps:
       - run: md build
         working-directory:
-      - uses: msys2/setup-msys2@v2
-        id: setup-msys2
-        with:
-          update: true
-          install: >-
-            patch
-        if: ${{ env.OS_VER != 'windows-2019' }}
-      - name: patch path
-        shell: msys2 {0}
-        run: echo PATCH=$(cygpath -wa $(command -v patch)) >> $GITHUB_ENV
-        if: ${{ steps.setup-msys2.outcome == 'success' }}
-      - uses: actions/cache@v3
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
         with:
-          path: C:\vcpkg\downloads
-          key: ${{ runner.os }}-vcpkg-download-${{ env.OS_VER }}-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-vcpkg-download-${{ env.OS_VER }}-
-            ${{ runner.os }}-vcpkg-download-
-      - uses: actions/cache@v3
+          # windows-11-arm has only 3.4.1, 3.4.2, 3.4.3, head
+          ruby-version: ${{ !endsWith(matrix.os, 'arm') && '3.1' || '3.4' }}
+          bundler: none
+          windows-toolchain: none
+
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
-          path: C:\vcpkg\installed
-          key: ${{ runner.os }}-vcpkg-installed-${{ matrix.os }}-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-vcpkg-installed-${{ matrix.os }}-
-            ${{ runner.os }}-vcpkg-installed-
-      - name: Install libraries with vcpkg
-        run: |
-          vcpkg --triplet x64-windows install libffi libyaml openssl readline zlib
-      - uses: actions/cache@v3
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - uses: ./.github/actions/setup/directories
         with:
-          path: C:\Users\runneradmin\AppData\Local\Temp\chocolatey
-          key: ${{ runner.os }}-chocolatey-${{ env.OS_VER }}-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-chocolatey-${{ env.OS_VER }}-
-            ${{ runner.os }}-chocolatey-
-      - name: Install libraries with chocolatey
+          srcdir: src
+          builddir: build
+          make-command: nmake
+          clean: true
+
+      - name: Install tools with scoop
         run: |
-          # Using Choco-Install for retries, but it doesn't detect failures properly
-          # if you pass multiple package names in a single command.
-          Choco-Install -PackageName winflexbison3
+          Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
+          iwr -useb get.scoop.sh | iex
+          Join-Path (Resolve-Path ~).Path "scoop\shims" >> $Env:GITHUB_PATH
+          scoop install vcpkg uutils-coreutils
         shell: pwsh
-      - name: git config
-        run: |
-          git config --global core.autocrlf false
-          git config --global core.eol lf
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v3
+
+      - name: Restore vcpkg artifact
+        id: restore-vcpkg
+        uses: actions/cache/restore@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
-          path: src
-      - uses: actions/cache@v3
+          path: src\vcpkg_installed
+          key: windows-${{ matrix.os }}-vcpkg-${{ hashFiles('src/vcpkg.json') }}
+
+      - name: Install libraries with vcpkg
+        run: |
+          vcpkg install --vcpkg-root=%USERPROFILE%\scoop\apps\vcpkg\current
+        working-directory: src
+        if: ${{ ! steps.restore-vcpkg.outputs.cache-hit }}
+
+      - name: Save vcpkg artifact
+        uses: actions/cache/save@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
-          path: src/.downloaded-cache
-          key: downloaded-cache
+          path: src\vcpkg_installed
+          key: windows-${{ matrix.os }}-vcpkg-${{ hashFiles('src/vcpkg.json') }}
+        if: ${{ ! steps.restore-vcpkg.outputs.cache-hit && (github.ref_name == 'master' || startsWith(github.ref_name, 'ruby_')) }}
+
       - name: setup env
+        # Available Ruby versions: https://github.com/actions/runner-images/blob/main/images/windows/Windows2019-Readme.md#ruby
         # %TEMP% is inconsistent with %TMP% and test-all expects they are consistent.
         # https://github.com/actions/virtual-environments/issues/712#issuecomment-613004302
         run: |
-          set VS=${{ matrix.vs }}
-          set VCVARS=${{ matrix.vcvars }}
-          if not "%VCVARS%" == "" goto :vcset
-            set VCVARS="C:\Program Files (x86)\Microsoft Visual Studio\%VS%\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
-            if not exist %VCVARS% set VCVARS="C:\Program Files\Microsoft Visual Studio\%VS%\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
-          :vcset
-          set | C:\msys64\usr\bin\sort > old.env
-          call %VCVARS%
-          set TMP=%USERPROFILE%\AppData\Local\Temp
-          set TEMP=%USERPROFILE%\AppData\Local\Temp
+          ::- Set up VC ${{ matrix.vc }}
+          set | sort > old.env
+          call ..\src\win32\vssetup.cmd ^
+            -arch=${{ matrix.target || 'amd64' }} ^
+            ${{ matrix.vcvars && '-vcvars_ver=' || '' }}${{ matrix.vcvars }}
+          nmake -f nul
+          set TMP=%RUNNER_TEMP%
+          set TEMP=%RUNNER_TEMP%
+          set MAKEFLAGS=l
           set /a TEST_JOBS=(15 * %NUMBER_OF_PROCESSORS% / 10) > nul
-          set | C:\msys64\usr\bin\sort > new.env
-          C:\msys64\usr\bin\comm -13 old.env new.env >> %GITHUB_ENV%
+          set RUBY_OPT_DIR=%GITHUB_WORKSPACE:\=/%/src/vcpkg_installed/%VCPKG_DEFAULT_TRIPLET%
+          set | sort > new.env
+          comm -13 old.env new.env >> %GITHUB_ENV%
           del *.env
+
+      - name: baseruby version
+        run: ruby -v
+
       - name: compiler version
         run: cl
-      - name: link libraries
-        run: |
-          for %%I in (C:\vcpkg\installed\x64-windows\bin\*.dll) do (
-            if not %%~nI == readline mklink %%~nxI %%I
-          )
-          for %%I in (libcrypto-1_1-x64 libssl-1_1-x64) do (
-            ren c:\Windows\System32\%%I.dll %%I.dll_
-          )
+
+      - name: volume info
+        run: Get-Volume
+        shell: pwsh
+
+      # TODO: We should use `../src` instead of `D:/a/ruby/ruby/src`
       - name: Configure
         run: >-
           ../src/win32/configure.bat --disable-install-doc
-          --with-opt-dir=C:/vcpkg/installed/x64-windows
+          --with-opt-dir=%RUBY_OPT_DIR%
+          --with-gmp
+
+      - run: nmake prepare-vcpkg
+
       - run: nmake incs
+
       - run: nmake extract-extlibs
+
+      # On all other platforms, test-spec depending on extract-gems (in common.mk) is enough.
+      # But not for this Visual Studio workflow. So here we extract gems before building.
+      - run: nmake extract-gems
+
+      # windows-11-arm runner cannot run `ruby tool/file2lastrev.rb --revision.h --output=revision.h`
+      - name: make revision.h
+        run: |
+          win32\lastrev.bat | win32\ifchange.bat --timestamp=.revision.time revision.h -
+          type revision.h
+        working-directory: src
+
       - run: nmake
-        env:
-          YACC: win_bison
-      - run: nmake test
-        timeout-minutes: 5
-      - run: nmake test-all
-        env:
-          RUBY_TESTOPTS: -j${{env.TEST_JOBS}} --job-status=normal
-        timeout-minutes: 60
-        continue-on-error: ${{ matrix.continue-on-error || false }}
-      - run: nmake test-spec
-        timeout-minutes: 10
-        continue-on-error: ${{ matrix.continue-on-error || false }}
-      - uses: k0kubun/action-slack@v2.0.0
+
+      - name: Set up Launchable
+        uses: ./.github/actions/launchable/setup
         with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "VS${{ matrix.vs }} / ${{ matrix.test_task || 'check' }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
+          os: windows-${{ matrix.os }}
+          launchable-token: ${{ secrets.LAUNCHABLE_TOKEN }}
+          builddir: build
+          srcdir: src
+          test-task: ${{ matrix.test_task || 'check' }}
+        continue-on-error: true
+        if: ${{ matrix.test_task != 'test-bundled-gems' }}
+        timeout-minutes: 3
+
+      - run: nmake ${{ matrix.test_task || 'check' }}
         env:
+          RUBY_TESTOPTS: -j${{ env.TEST_JOBS || 4 }}
+        timeout-minutes: 70
+
+      - uses: ./.github/actions/slack
+        with:
+          label: Windows ${{ matrix.os }} / VC ${{ matrix.vc }} / ${{ matrix.test_task || 'check' }}
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ failure() }}
+
+  result:
+    if: ${{ always() }}
+    name: ${{ github.workflow }} result
+    runs-on: windows-latest
+    needs: [make]
+    steps:
+      - run: exit 1
+        working-directory:
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
 
 defaults:
   run:
diff --git a/.github/workflows/wsl.yml b/.github/workflows/wsl.yml
new file mode 100644
index 0000000000..640f18ce42
--- /dev/null
+++ b/.github/workflows/wsl.yml
@@ -0,0 +1,70 @@
+name: Ubuntu on WSL
+
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
+
+jobs:
+  wsl:
+    runs-on: windows-2025
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - name: Install or update WSL
+        uses: Ubuntu/WSL/.github/actions/wsl-install@main
+        with:
+          distro: Ubuntu-24.04
+
+      - name: Install dependencies
+        uses: Ubuntu/WSL/.github/actions/wsl-bash@main
+        with:
+         distro: Ubuntu-24.04
+         working-dir: /tmp/github/
+         exec: |
+            DEBIAN_FRONTEND=noninteractive sudo apt update
+            DEBIAN_FRONTEND=noninteractive sudo apt install -y ruby build-essential autoconf libssl-dev libyaml-dev zlib1g-dev libgmp-dev libffi-dev
+
+      - name: Check out the repository
+        uses: Ubuntu/WSL/.github/actions/wsl-checkout@main
+        with:
+          distro: Ubuntu-24.04
+          working-dir: /tmp/github/
+          submodules: true
+
+      - name: Build
+        uses: Ubuntu/WSL/.github/actions/wsl-bash@main
+        with:
+         distro: Ubuntu-24.04
+         working-dir: /tmp/github/
+         exec: |
+            ./autogen.sh
+            ./configure --disable-install-doc
+            make ruby -j4
+            make extract-gems
+            make -j4
+
+      - name: Test
+        uses: Ubuntu/WSL/.github/actions/wsl-bash@main
+        with:
+         distro: Ubuntu-24.04
+         working-dir: /tmp/github/
+         exec: |
+            ./ruby -v
+            # make check TESTS="-j4" MSPECOPT="-j"
diff --git a/.github/workflows/yjit-macos.yml b/.github/workflows/yjit-macos.yml
new file mode 100644
index 0000000000..a59b4d6508
--- /dev/null
+++ b/.github/workflows/yjit-macos.yml
@@ -0,0 +1,198 @@
+name: YJIT macOS
+on:
+  push:
+    branches:
+      - master
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  cargo:
+    name: cargo test
+
+    runs-on: macos-14
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - run: RUST_BACKTRACE=1 cargo test
+        working-directory: yjit
+
+      # Also compile and test with all features enabled
+      - run: RUST_BACKTRACE=1 cargo test --all-features
+        working-directory: yjit
+
+      # Check that we can build in release mode too
+      - run: cargo build --release
+        working-directory: yjit
+
+  make:
+    strategy:
+      matrix:
+        include:
+          - test_task: 'check'
+            configure: '--enable-yjit'
+            yjit_opts: '--yjit'
+          - test_task: 'check'
+            configure: '--enable-yjit=dev'
+            yjit_opts: '--yjit-call-threshold=1 --yjit-verify-ctx --yjit-code-gc'
+            specopts: '-T --yjit-call-threshold=1 -T --yjit-verify-ctx -T --yjit-code-gc'
+      fail-fast: false
+
+    env:
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+      RUN_OPTS: ${{ matrix.yjit_opts }}
+      SPECOPTS: ${{ matrix.specopts }}
+
+    runs-on: macos-14
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - name: Install libraries
+        uses: ./.github/actions/setup/macos
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
+          # Set fetch-depth: 10 so that Launchable can receive commits information.
+          fetch-depth: 10
+
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc ${{ matrix.configure }}
+
+      - run: make prepare-gems
+        if: ${{ matrix.test_task == 'test-bundled-gems' }}
+
+      - run: make
+
+      - name: Verify that --yjit-dump-disasm works
+        run: |
+          ./miniruby --yjit-call-threshold=1 --yjit-dump-disasm -e0 | \
+          wc -l | \
+          ruby -ne 'raise "Disassembly seems broken in dev build (output has too few lines)" unless $_.to_i > 10'
+        if: ${{ contains(matrix.configure, 'jit=dev') }}
+
+      - name: Set ENV for YJIT
+        run: |
+          echo "RUBY_YJIT_ENABLE=1" >> $GITHUB_ENV
+          echo "RUBY_CRASH_REPORT=$(pwd)/rb_crash_%p.txt" >> $GITHUB_ENV
+
+      - name: Set test options for skipped tests
+        run: |
+          set -x
+          TESTS="$(echo "${{ matrix.skipped_tests }}" | sed 's| |$$/ -n!/|g;s|^|-n!/|;s|$|$$/|')"
+          echo "TESTS=${TESTS}" >> $GITHUB_ENV
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
+
+      - name: Set up Launchable
+        id: launchable
+        uses: ./.github/actions/launchable/setup
+        with:
+          os: macos-14
+          test-opts: ${{ matrix.configure }}
+          launchable-token: ${{ secrets.LAUNCHABLE_TOKEN }}
+          builddir: build
+          srcdir: src
+          is-yjit: true
+        continue-on-error: true
+        timeout-minutes: 3
+
+      - name: make ${{ matrix.test_task }}
+        run: |
+          test -n "${LAUNCHABLE_STDOUT}" && exec 1> >(tee "${LAUNCHABLE_STDOUT}")
+          test -n "${LAUNCHABLE_STDERR}" && exec 2> >(tee "${LAUNCHABLE_STDERR}")
+
+          set -x
+          make -s ${{ matrix.test_task }} ${TESTS:+TESTS="$TESTS"} \
+            RUN_OPTS="$RUN_OPTS" \
+            SPECOPTS="$SPECOPTS"
+        timeout-minutes: 60
+        env:
+          RUBY_TESTOPTS: '-q --tty=no'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
+          SYNTAX_SUGGEST_TIMEOUT: '5'
+          PRECHECK_BUNDLED_GEMS: 'no'
+          LAUNCHABLE_STDOUT: ${{ steps.launchable.outputs.stdout_report_path }}
+          LAUNCHABLE_STDERR: ${{ steps.launchable.outputs.stderr_report_path }}
+        continue-on-error: ${{ matrix.continue-on-test_task || false }}
+
+      - name: make skipped tests
+        run: |
+          make -s test-all TESTS="${TESTS//-n!\//-n/}"
+        env:
+          GNUMAKEFLAGS: ''
+          RUBY_TESTOPTS: '-v --tty=no'
+          PRECHECK_BUNDLED_GEMS: 'no'
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
+        continue-on-error: ${{ matrix.continue-on-skipped_tests || false }}
+
+      - name: Dump crash logs
+        if: ${{ failure() }}
+        continue-on-error: true
+        run: |
+          tail --verbose --lines=+1 rb_crash_*.txt
+          exit 1
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.test_task }} ${{ matrix.configure }} ${{ matrix.yjit_opts }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+  result:
+    if: ${{ always() }}
+    name: ${{ github.workflow }} result
+    runs-on: macos-14
+    needs: [make]
+    steps:
+      - name: ${{ github.workflow }} jobs have failed
+        run: exit 1
+        working-directory:
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/yjit-ubuntu.yml b/.github/workflows/yjit-ubuntu.yml
index 3c0d5c046c..150f0b3275 100644
--- a/.github/workflows/yjit-ubuntu.yml
+++ b/.github/workflows/yjit-ubuntu.yml
@@ -3,147 +3,237 @@ on:
   push:
     paths-ignore:
       - 'doc/**'
+      - '**/man/*'
       - '**.md'
       - '**.rdoc'
       - '**/.document'
+      - '.*.yml'
   pull_request:
-    paths-ignore:
-      - 'doc/**'
-      - '**.md'
-      - '**.rdoc'
-      - '**/.document'
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
 
 concurrency:
   group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
   cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
 
+permissions:
+  contents: read
+
 jobs:
   cargo:
-    name: Rust cargo test
+    name: cargo test
+
     # GitHub Action's image seems to already contain a Rust 1.58.0.
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
       # For now we can't run cargo test --offline because it complains about the
       # capstone dependency, even though the dependency is optional
       #- run: cargo test --offline
+
       - run: RUST_BACKTRACE=1 cargo test
         working-directory: yjit
+
       # Also compile and test with all features enabled
       - run: RUST_BACKTRACE=1 cargo test --all-features
         working-directory: yjit
+
       # Check that we can build in release mode too
       - run: cargo build --release
         working-directory: yjit
+
+  lint:
+    name: cargo clippy
+
+    # GitHub Action's image seems to already contain a Rust 1.58.0.
+    runs-on: ubuntu-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      # Check that we don't have linting errors in release mode, too
+      - run: cargo clippy --all-targets --all-features
+        working-directory: yjit
+
   make:
     strategy:
       fail-fast: false
       matrix:
         include:
-          - test_task: "check-yjit-bindings"
-            configure: "--with-gcc=clang-12 --enable-yjit=dev"
+          - test_task: 'yjit-bindgen'
+            hint: 'To fix: use patch in logs'
+            # Build with YJIT+ZJIT for output that works in the most number of configurations
+            configure: '--with-gcc=clang-14 --enable-yjit=dev --enable-zjit'
+            libclang_path: '/usr/lib/llvm-14/lib/libclang.so.1'
 
-          - test_task: "check"
-            configure: "--enable-yjit RUSTC='rustc +1.58.1'" # release build
-            rust_version: "1.58.1"
+          - test_task: 'check'
+            # YJIT should be automatically built in release mode on x86-64 Linux with rustc present
+            #configure: "--enable-yjit RUSTC='rustc +1.58.0'"
+            configure: "RUSTC='rustc +1.58.0'"
+            rust_version: '1.58.0'
 
-          - test_task: "check"
-            configure: "--enable-yjit=dev"
+          - test_task: 'check'
+            configure: '--enable-yjit=dev'
 
-          - test_task: "check"
-            configure: "--enable-yjit=dev"
-            yjit_opts: "--yjit-call-threshold=1"
+          - test_task: 'check'
+            configure: '--enable-yjit=dev'
+            yjit_opts: '--yjit-call-threshold=1 --yjit-verify-ctx --yjit-code-gc'
+            specopts: '-T --yjit-call-threshold=1 -T --yjit-verify-ctx -T --yjit-code-gc'
 
-          - test_task: "test-all TESTS=--repeat-count=2"
-            configure: "--enable-yjit=dev"
+          - test_task: 'test-bundled-gems'
+            configure: '--enable-yjit=dev'
 
-          - test_task: "test-bundled-gems"
-            configure: "--enable-yjit=dev"
-
-          - test_task: "yjit-bench"
-            configure: "--enable-yjit=dev"
-            yjit_bench_opts: "--yjit-stats"
     env:
-      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
       RUN_OPTS: ${{ matrix.yjit_opts }}
       YJIT_BENCH_OPTS: ${{ matrix.yjit_bench_opts }}
+      SPECOPTS: ${{ matrix.specopts }}
       RUBY_DEBUG: ci
-      BUNDLE_JOBS: 8 # for yjit-bench
-    runs-on: ubuntu-20.04
-    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+      RUST_BACKTRACE: 1
+
+    runs-on: ubuntu-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
     steps:
-      - run: mkdir build
-        working-directory:
-      - name: Install libraries
-        run: |
-          set -x
-          sudo apt-get update -q || :
-          sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev bison autoconf ruby
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - uses: ./.github/actions/setup/ubuntu
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
+        with:
+          ruby-version: '3.1'
+          bundler: none
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
+          # Set fetch-depth: 10 so that Launchable can receive commits information.
+          fetch-depth: 10
+
       - name: Install Rust
         if: ${{ matrix.rust_version }}
         run: rustup install ${{ matrix.rust_version }} --profile minimal
-      - name: git config
-        run: |
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v3
-        with:
-          path: src
-      - uses: actions/cache@v3
-        with:
-          path: src/.downloaded-cache
-          key: downloaded-cache
-      - name: Fixed world writable dirs
-        run: |
-          chmod -v go-w $HOME $HOME/.config
-          sudo chmod -R go-w /usr/share
-          sudo bash -c 'IFS=:; for d in '"$PATH"'; do chmod -v go-w $d; done' || :
-      - name: Set ENV
-        run: |
-          echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
-      - run: ./autogen.sh
-        working-directory: src
+
+      - name: Remove cargo
+        # Since this tests a `rustc` build for release, remove `cargo` to ensure
+        # that only `rustc` is used.
+        if: ${{ contains(matrix.configure, 'rustc') }}
+        run: sudo rm $(which -a cargo | uniq)
+
       - name: Run configure
         run: ../src/configure -C --disable-install-doc --prefix=$(pwd)/install ${{ matrix.configure }}
+
       - run: make incs
+
       - run: make prepare-gems
         if: ${{ matrix.test_task == 'test-bundled-gems' }}
-      - run: make -j
-      - run: make leaked-globals
-        if: ${{ matrix.test_task == 'check' }}
-      - name: Create dummy files in build dir
+
+      - run: make
+
+      - name: Verify that --yjit-dump-disasm works
+        run: |
+          ./miniruby --yjit-call-threshold=1 --yjit-dump-disasm -e0 | \
+          wc -l | \
+          ruby -ne 'raise "Disassembly seems broken in dev build (output has too few lines)" unless $_.to_i > 10'
+        if: ${{ contains(matrix.configure, 'jit=dev') }}
+
+      - name: Set ENV for YJIT
         run: |
-          ./miniruby -e '(("a".."z").to_a+("A".."Z").to_a+("0".."9").to_a+%w[foo bar test zzz]).each{|basename|File.write("#{basename}.rb", "raise %(do not load #{basename}.rb)")}'
-        if: ${{ matrix.test_task == 'check' }}
-      - name: Enable YJIT through ENV
-        run: echo "RUBY_YJIT_ENABLE=1" >> $GITHUB_ENV
+          echo "RUBY_YJIT_ENABLE=1" >> $GITHUB_ENV
+          echo "RUBY_CRASH_REPORT=$(pwd)/rb_crash_%p.txt" >> $GITHUB_ENV
+
+      # Check that the binary was built with YJIT
+      - name: Check YJIT enabled
+        run: ./miniruby --yjit -v | grep "+YJIT"
+
+      - name: Set up Launchable
+        id: launchable
+        uses: ./.github/actions/launchable/setup
+        with:
+          os: ubuntu-22.04
+          test-opts: ${{ matrix.configure }}
+          launchable-token: ${{ secrets.LAUNCHABLE_TOKEN }}
+          builddir: build
+          srcdir: src
+          is-yjit: true
+        continue-on-error: true
+        timeout-minutes: 3
+
       - name: make ${{ matrix.test_task }}
-        run: make -s -j ${{ matrix.test_task }} RUN_OPTS="$RUN_OPTS" YJIT_BENCH_OPTS="$YJIT_BENCH_OPTS"
-        timeout-minutes: 60
-        env:
-          RUBY_TESTOPTS: "-q --tty=no"
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ""
-          PRECHECK_BUNDLED_GEMS: "no"
-        continue-on-error: ${{ matrix.test_task == 'yjit-bench' }}
-      - name: Show ${{ github.event.pull_request.base.ref }} GitHub URL for yjit-bench comparison
-        run: echo "https://github.com/${BASE_REPO}/commit/${BASE_SHA}"
+        run: |
+          test -n "${LAUNCHABLE_STDOUT}" && exec 1> >(tee "${LAUNCHABLE_STDOUT}")
+          test -n "${LAUNCHABLE_STDERR}" && exec 2> >(tee "${LAUNCHABLE_STDERR}")
+
+          set -x
+          make -s ${{ matrix.test_task }} ${TESTS:+TESTS="$TESTS"} \
+            RUN_OPTS="$RUN_OPTS" MSPECOPT=--debug SPECOPTS="$SPECOPTS" \
+            YJIT_BENCH_OPTS="$YJIT_BENCH_OPTS" YJIT_BINDGEN_DIFF_OPTS="$YJIT_BINDGEN_DIFF_OPTS"
+        timeout-minutes: 90
         env:
-          BASE_REPO: ${{ github.event.pull_request.base.repo.full_name }}
-          BASE_SHA: ${{ github.event.pull_request.base.sha }}
-        if: ${{ matrix.test_task == 'yjit-bench' && startsWith(github.event_name, 'pull') }}
-      - uses: k0kubun/action-slack@v2.0.0
+          RUBY_TESTOPTS: '-q --tty=no'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
+          PRECHECK_BUNDLED_GEMS: 'no'
+          SYNTAX_SUGGEST_TIMEOUT: '5'
+          YJIT_BINDGEN_DIFF_OPTS: '--exit-code'
+          LIBCLANG_PATH: ${{ matrix.libclang_path }}
+          LAUNCHABLE_STDOUT: ${{ steps.launchable.outputs.stdout_report_path }}
+          LAUNCHABLE_STDERR: ${{ steps.launchable.outputs.stderr_report_path }}
+        continue-on-error: ${{ matrix.continue-on-test_task || false }}
+
+      - name: Dump crash logs
+        if: ${{ failure() }}
+        continue-on-error: true
+        run: |
+          tail --verbose --lines=+1 rb_crash_*.txt
+          exit 1
+
+      - uses: ./.github/actions/slack
         with:
-          payload: |
-            {
-              "ci": "GitHub Actions",
-              "env": "${{ matrix.os }} / ${{ matrix.test_task }}${{ matrix.configure }}",
-              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
-              "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
-            }
-        env:
+          label: ${{ matrix.test_task }} ${{ matrix.configure }}
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: ${{ failure() && github.event_name == 'push' }}
+        if: ${{ failure() }}
+
+  result:
+    if: ${{ always() }}
+    name: ${{ github.workflow }} result
+    runs-on: ubuntu-latest
+    needs: [make]
+    steps:
+      - run: exit 1
+        working-directory:
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
 
 defaults:
   run:
diff --git a/.github/workflows/zjit-macos.yml b/.github/workflows/zjit-macos.yml
new file mode 100644
index 0000000000..a638907811
--- /dev/null
+++ b/.github/workflows/zjit-macos.yml
@@ -0,0 +1,214 @@
+name: ZJIT macOS
+on:
+  push:
+    branches:
+      - master
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  make:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - test_task: 'check'
+            run_opts: '--zjit-call-threshold=1'
+            specopts: '-T --zjit-call-threshold=1'
+            configure: '--enable-zjit=dev'
+
+          - test_task: 'check'
+            run_opts: '--zjit-disable-hir-opt --zjit-call-threshold=1'
+            specopts: '-T --zjit-disable-hir-opt -T --zjit-call-threshold=1'
+            configure: '--enable-zjit=dev'
+
+          - test_task: 'zjit-check' # zjit-test + quick feedback of test_zjit.rb
+            configure: '--enable-yjit=dev --enable-zjit'
+            rust_version: "1.85.0"
+
+          - test_task: 'ruby'
+            hint: 'combo build test'
+            configure: '--enable-yjit --enable-zjit'
+
+    env:
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+      RUN_OPTS: ${{ matrix.run_opts }}
+      SPECOPTS: ${{ matrix.specopts }}
+      TESTOPTS: ${{ matrix.testopts }}
+      ZJIT_RB_BUG: 1
+
+    runs-on: macos-14
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - name: Install libraries
+        uses: ./.github/actions/setup/macos
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
+          # Set fetch-depth: 10 so that Launchable can receive commits information.
+          fetch-depth: 10
+
+      - name: Install Rust
+        if: ${{ matrix.rust_version }}
+        run: |
+          rustup install ${{ matrix.rust_version }} --profile minimal
+          rustup default ${{ matrix.rust_version }}
+
+      - uses: taiki-e/install-action@v2
+        with:
+          tool: nextest@0.9
+        if: ${{ matrix.test_task == 'zjit-check' }}
+
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc ${{ matrix.configure }}
+
+      - run: make
+
+      - name: Verify that --zjit-dump-disasm works
+        run: |
+          ./miniruby --zjit-call-threshold=1 --zjit-dump-disasm -e0 | \
+          wc -l | \
+          ruby -ne 'raise "Disassembly seems broken in dev build (output has too few lines)" unless $_.to_i > 10'
+        if: ${{ contains(matrix.configure, 'jit=dev') }}
+
+      - name: Set ENV for ZJIT
+        run: |
+          echo "RUBY_CRASH_REPORT=$(pwd)/rb_crash_%p.txt" >> $GITHUB_ENV
+
+      - name: make ${{ matrix.test_task }}
+        run: |
+          set -x
+          make -s ${{ matrix.test_task }} ${TESTS:+TESTS="$TESTS"} \
+            RUN_OPTS="$RUN_OPTS" \
+            SPECOPTS="$SPECOPTS" \
+            TESTOPTS="$TESTOPTS"
+        timeout-minutes: 60
+        env:
+          RUBY_TESTOPTS: '-q --tty=no'
+          EXCLUDES: '../src/test/.excludes-zjit'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
+          SYNTAX_SUGGEST_TIMEOUT: '5'
+          PRECHECK_BUNDLED_GEMS: 'no'
+        continue-on-error: ${{ matrix.continue-on-test_task || false }}
+
+      - name: Dump crash logs
+        if: ${{ failure() }}
+        continue-on-error: true
+        run: |
+          tail --verbose --lines=+1 rb_crash_*.txt
+          exit 1
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.test_task }} ${{ matrix.configure }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+  result:
+    if: ${{ always() }}
+    name: ${{ github.workflow }} result
+    runs-on: macos-14
+    needs: [make]
+    steps:
+      - run: exit 1
+        working-directory:
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
+
+  # Separated from `make` job to avoid making it a required status check for now
+  ruby-bench:
+    strategy:
+      matrix:
+        include:
+          # Test --call-threshold=2 with 2 iterations in total
+          - ruby_opts: '--zjit-call-threshold=2'
+            bench_opts: '--warmup=1 --bench=1 --excludes=lobsters'
+            configure: '--enable-zjit=dev_nodebug' # --enable-zjit=dev is too slow
+
+    runs-on: macos-14
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - uses: ./.github/actions/setup/macos
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc --prefix="$(pwd)/install" ${{ matrix.configure }}
+
+      - run: make install
+
+      # setup/directories set MAKEFLAGS=-j4 for macOS, which randomly fails sqlite3.gem builds
+      - name: Unset MAKEFLAGS
+        run: echo "MAKEFLAGS=" >> "$GITHUB_ENV"
+
+      - name: Checkout ruby-bench
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          repository: ruby/ruby-bench
+          path: ruby-bench
+
+      # If you want to skip failing benchmark, consider using `--excludes`.
+      # e.g. `bench_opts: '--warmup=1 --bench=1 --excludes=railsbench,lobsters'`
+      - name: Run ruby-bench
+        run: ruby run_benchmarks.rb -e "zjit::../build/install/bin/ruby ${{ matrix.ruby_opts }}" ${{ matrix.bench_opts }}
+        working-directory: ruby-bench
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ruby-bench ${{ matrix.bench_opts }} ${{ matrix.ruby_opts }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/zjit-ubuntu.yml b/.github/workflows/zjit-ubuntu.yml
new file mode 100644
index 0000000000..28bfec963e
--- /dev/null
+++ b/.github/workflows/zjit-ubuntu.yml
@@ -0,0 +1,267 @@
+name: ZJIT Ubuntu
+on:
+  push:
+    branches:
+      - master
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  lint:
+    name: cargo clippy
+
+    runs-on: ubuntu-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - run: cargo clippy --all-targets --all-features
+        working-directory: zjit
+
+  make:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - test_task: 'check'
+            run_opts: '--zjit-call-threshold=1'
+            specopts: '-T --zjit-call-threshold=1'
+            configure: '--enable-zjit=dev'
+
+          - test_task: 'check'
+            run_opts: '--zjit-disable-hir-opt --zjit-call-threshold=1'
+            specopts: '-T --zjit-disable-hir-opt -T --zjit-call-threshold=1'
+            configure: '--enable-zjit=dev'
+
+            # The optimizer benefits from at least 1 iteration of profiling. Also, many
+            # regression tests in bootstraptest/test_yjit.rb assume call-threshold=2.
+          - test_task: 'btest'
+            run_opts: '--zjit-call-threshold=2'
+            configure: '--enable-zjit=dev'
+
+          - test_task: 'zjit-check' # zjit-test + quick feedback of test_zjit.rb
+            configure: '--enable-yjit --enable-zjit=dev'
+            rust_version: '1.85.0'
+
+          - test_task: 'zjit-bindgen'
+            hint: 'To fix: use patch in logs'
+            # Build with YJIT+ZJIT for output that works in the most number of configurations
+            configure: '--enable-zjit=dev --enable-yjit --with-gcc=clang-16'
+            clang_path: '/usr/bin/clang-16'
+            runs-on: 'ubuntu-24.04' # for clang-16
+
+          - test_task: 'test-bundled-gems'
+            configure: '--enable-zjit=dev'
+            run_opts: '--zjit-call-threshold=1'
+
+    env:
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+      RUN_OPTS: ${{ matrix.run_opts }}
+      YJIT_BENCH_OPTS: ${{ matrix.yjit_bench_opts }}
+      SPECOPTS: ${{ matrix.specopts }}
+      TESTOPTS: ${{ matrix.testopts }}
+      RUBY_DEBUG: ci
+      BUNDLE_JOBS: 8 # for yjit-bench
+      RUST_BACKTRACE: 1
+      ZJIT_RB_BUG: 1
+
+    runs-on: ${{ matrix.runs-on || 'ubuntu-22.04' }}
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - uses: ./.github/actions/setup/ubuntu
+
+      - uses: ruby/setup-ruby@b90be12699fdfcbee4440c2bba85f6f460446bb0 # v1.279.0
+        with:
+          ruby-version: '3.1'
+          bundler: none
+
+      - uses: taiki-e/install-action@v2
+        with:
+          tool: nextest@0.9
+        if: ${{ matrix.test_task == 'zjit-check' }}
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
+          # Set fetch-depth: 10 so that Launchable can receive commits information.
+          fetch-depth: 10
+
+      - name: Install Rust
+        if: ${{ matrix.rust_version }}
+        run: |
+          rustup install ${{ matrix.rust_version }} --profile minimal
+          rustup default ${{ matrix.rust_version }}
+
+      - name: Install rustfmt
+        if: ${{ matrix.test_task == 'zjit-bindgen' }}
+        run: rustup component add rustfmt
+
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc --prefix=$(pwd)/install ${{ matrix.configure }}
+
+      - run: make incs
+
+      - run: make prepare-gems
+        if: ${{ matrix.test_task == 'test-bundled-gems' }}
+
+      - run: make
+
+      - name: Verify that --zjit-dump-disasm works
+        run: |
+          ./miniruby --zjit-call-threshold=1 --zjit-dump-disasm -e0 | \
+          wc -l | \
+          ruby -ne 'raise "Disassembly seems broken in dev build (output has too few lines)" unless $_.to_i > 10'
+        if: ${{ contains(matrix.configure, 'jit=dev') }}
+
+      # Check that the binary was built with ZJIT
+      - name: Check ZJIT enabled
+        run: ./miniruby --zjit -v | grep "+ZJIT"
+        if: ${{ matrix.configure != '--disable-zjit' }}
+
+      - name: Set ENV for ZJIT
+        run: |
+          echo "RUBY_CRASH_REPORT=$(pwd)/rb_crash_%p.txt" >> $GITHUB_ENV
+
+      - name: make ${{ matrix.test_task }}
+        run: |
+          set -x
+          make -s ${{ matrix.test_task }} ${TESTS:+TESTS="$TESTS"} \
+            RUN_OPTS="$RUN_OPTS" MSPECOPT=--debug SPECOPTS="$SPECOPTS" \
+            TESTOPTS="$TESTOPTS" \
+            ZJIT_BINDGEN_DIFF_OPTS="$ZJIT_BINDGEN_DIFF_OPTS"
+        timeout-minutes: 90
+        env:
+          RUBY_TESTOPTS: '-q --tty=no'
+          EXCLUDES: '../src/test/.excludes-zjit'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
+          PRECHECK_BUNDLED_GEMS: 'no'
+          SYNTAX_SUGGEST_TIMEOUT: '5'
+          ZJIT_BINDGEN_DIFF_OPTS: '--exit-code'
+          CLANG_PATH: ${{ matrix.clang_path }}
+        continue-on-error: ${{ matrix.continue-on-test_task || false }}
+
+      - name: Dump crash logs
+        if: ${{ failure() }}
+        continue-on-error: true
+        run: |
+          tail --verbose --lines=+1 rb_crash_*.txt
+          exit 1
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.test_task }} ${{ matrix.configure }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+  result:
+    if: ${{ always() }}
+    name: ${{ github.workflow }} result
+    runs-on: ubuntu-22.04
+    needs: [make]
+    steps:
+      - name: ${{ github.workflow }} jobs have failed
+        run: exit 1
+        working-directory:
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
+
+  # Separated from `make` job to avoid making it a required status check for now
+  ruby-bench:
+    strategy:
+      matrix:
+        include:
+          # Test --call-threshold=2 with 2 iterations in total
+          - ruby_opts: '--zjit-call-threshold=2'
+            bench_opts: '--warmup=1 --bench=1 --excludes=lobsters'
+            configure: '--enable-zjit=dev_nodebug' # --enable-zjit=dev is too slow
+
+    runs-on: ubuntu-24.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+
+      - uses: ./.github/actions/setup/ubuntu
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc --prefix="$(pwd)/install" ${{ matrix.configure }}
+
+      - run: make install
+
+      - name: Checkout ruby-bench
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        with:
+          repository: ruby/ruby-bench
+          path: ruby-bench
+
+      # If you want to skip failing benchmark, consider using `--excludes`.
+      # e.g. `bench_opts: '--warmup=1 --bench=1 --excludes=railsbench,lobsters'`
+      - name: Run ruby-bench
+        run: ruby run_benchmarks.rb -e "zjit::../build/install/bin/ruby ${{ matrix.ruby_opts }}" ${{ matrix.bench_opts }}
+        working-directory: ruby-bench
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ruby-bench ${{ matrix.bench_opts }} ${{ matrix.ruby_opts }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.gitignore b/.gitignore
index c15b68f676..6cf5fb5f32 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,17 +14,20 @@
 *.inc
 *.log
 *.o
+*.o.tmp
 *.obj
 *.old
 *.orig
 *.pch
 *.pdb
 *.rbinc
+*.rbbin
 *.rej
 *.s
 *.sav
 *.sl
 *.so
+*.so.*
 *.swp
 *.yarb
 *~
@@ -48,6 +51,7 @@ y.tab.c
 *.gcno
 *.gcov
 *.vscode
+!misc/.vscode
 lcov*.info
 
 # /
@@ -121,6 +125,7 @@ lcov*.info
 /repack
 /revision.h
 /revision.tmp
+/ripper.tmp.y
 /riscos
 /rubicon
 /ruby
@@ -134,17 +139,19 @@ lcov*.info
 /test.rb
 /test-coverage.dat
 /tmp
+/vcpkg_installed
 /transdb.h
 /uncommon.mk
 /verconf.h
 /verconf.mk
 /web
-/yasmdata.rb
 
 # /bin/
 
 /bin/*.exe
 /bin/*.dll
+/bin/goruby
+/bin/ruby
 
 # /benchmark/
 /benchmark/bm_require.data
@@ -160,6 +167,7 @@ lcov*.info
 
 # /coroutine/
 !/coroutine/**/*.s
+!/coroutine/**/*.S
 
 # /enc/trans/
 /enc/trans/*.c
@@ -199,8 +207,10 @@ lcov*.info
 
 # /ext/ripper/
 /ext/ripper/eventids1.c
+/ext/ripper/eventids1.h
 /ext/ripper/.eventids2-check
 /ext/ripper/eventids2table.c
+/ext/ripper/ripper_init.c
 /ext/ripper/ripper.*
 /ext/ripper/ids1
 /ext/ripper/ids2
@@ -222,7 +232,7 @@ lcov*.info
 # /misc/
 /misc/**/__pycache__
 
-# /spec/bundler
+# for `make test-bundler`
 /.rspec_status
 
 # /tool/
@@ -232,14 +242,39 @@ lcov*.info
 # /win32/
 /win32/*.ico
 
-# MJIT
-/rb_mjit_header.h
-/mjit_config.h
-/include/ruby-*/*/rb_mjit_min_header-*.h
-/lib/mjit/instruction.rb
 
 # YJIT
 /yjit-bench
+/yjit_exit_locations.dump
+
+# Rust
+/target
 
 # /wasm/
 /wasm/tests/*.wasm
+
+# prism
+/lib/prism/compiler.rb
+/lib/prism/dispatcher.rb
+/lib/prism/dot_visitor.rb
+/lib/prism/dsl.rb
+/lib/prism/inspect_visitor.rb
+/lib/prism/mutation_compiler.rb
+/lib/prism/node.rb
+/lib/prism/reflection.rb
+/lib/prism/serialize.rb
+/lib/prism/visitor.rb
+/prism/api_node.c
+/prism/ast.h
+/prism/diagnostic.c
+/prism/diagnostic.h
+/prism/node.c
+/prism/prettyprint.c
+/prism/serialize.c
+/prism/token_type.c
+/prism/srcs.mk
+
+# tool/update-NEWS-gemlist.rb
+/bundled_gems.json
+/default_gems.json
+/gems/default_gems
diff --git a/.mailmap b/.mailmap
new file mode 100644
index 0000000000..213a0f4916
--- /dev/null
+++ b/.mailmap
@@ -0,0 +1,431 @@
+git[bot]                                <svn-admin@ruby-lang.org>
+git[bot]                                <svn-admin@ruby-lang.org> git <svn@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+svn[bot]                                <svn-admin@ruby-lang.org> svn <svn@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# a_matsuda
+Akira Matsuda                           <ronnie@dio.jp>
+Akira Matsuda                           <ronnie@dio.jp> <a_matsuda@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# aamine
+Minero Aoki                             <aamine@loveruby.net>
+Minero Aoki                             <aamine@loveruby.net> <aamine@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# akira
+akira yamada                            <akira@ruby-lang.org>
+## akira yamada                         <akira@ruby-lang.org> <akira@rice.p.arika.org>
+akira yamada                            <akira@ruby-lang.org> <akira@arika.org>
+akira yamada                            <akira@ruby-lang.org> <akira@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# akiyoshi
+AKIYOSHI, Masamichi                     <masamichi.akiyoshi@hp.com>
+AKIYOSHI, Masamichi                     <masamichi.akiyoshi@hp.com> <akiyoshi@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# akr
+Tanaka Akira                            <akr@fsij.org>
+Tanaka Akira                            <akr@fsij.org> <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# arai
+Koji Arai                               <jca02266@nifty.ne.jp>
+Koji Arai                               <jca02266@nifty.ne.jp> <arai@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# arton
+Akio Tajima                             <artonx@yahoo.co.jp>
+Akio Tajima                             <artonx@yahoo.co.jp> <arton@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# aycabta
+aycabta                                 <aycabta@gmail.com>
+aycabta                                 <aycabta@gmail.com> <aycabta@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ayumin
+Ayumu AIZAWA                            <ayumu.aizawa@gmail.com>
+Ayumu AIZAWA                            <ayumu.aizawa@gmail.com> <ayumin@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# azav
+Alexander Zavorine                      <alexandre.zavorine@nokia.com>
+Alexander Zavorine                      <alexandre.zavorine@nokia.com> <azav@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# charliesome
+Charlie Somerville                      <charliesome@ruby-lang.org>
+Charlie Somerville                      <charliesome@ruby-lang.org> <charliesome@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# dave
+Dave Thomas                             <dave@pragprog.com>
+Dave Thomas                             <dave@pragprog.com> <dave@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# davidflanagan
+David Flanagan                          <davidflanagan@ruby-lang.org>
+David Flanagan                          <davidflanagan@ruby-lang.org> <david@think32>
+David Flanagan                          <davidflanagan@ruby-lang.org> <david@davidflanagan.com>
+David Flanagan                          <davidflanagan@ruby-lang.org> <davidflanagan@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# dblack
+David A. Black                          <dblack@rubypal.com>
+David A. Black                          <dblack@rubypal.com> <dblack@wobblini.net>
+David A. Black                          <dblack@rubypal.com> <dblack@superlink.net>
+David A. Black                          <dblack@rubypal.com> <dblack@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# drbrain
+Eric Hodel                              <drbrain@segment7.net>
+Eric Hodel                              <drbrain@segment7.net> <drbrain@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# duerst
+Martin Dürst                            <duerst@it.aoyama.ac.jp>
+Martin Dürst                            <duerst@it.aoyama.ac.jp> <duerst@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# eban
+WATANABE Hirofumi                       <eban@ruby-lang.org>
+WATANABE Hirofumi                       <eban@ruby-lang.org> <eban@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# emboss
+Martin Bosslet                          <Martin.Bosslet@gmail.com>
+Martin Bosslet                          <Martin.Bosslet@gmail.com> <Martin.Bosslet@googlemail.com>
+Martin Bosslet                          <Martin.Bosslet@gmail.com> <emboss@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# eregon
+Benoit Daloze                           <eregontp@gmail.com>
+Benoit Daloze                           <eregontp@gmail.com> <eregon@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# evan
+Evan Phoenix                            <evan@ruby-lang.org>
+Evan Phoenix                            <evan@ruby-lang.org> <evan@fallingsnow.net>
+Evan Phoenix                            <evan@ruby-lang.org> <evan@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# glass
+Masaki Matsushita                       <glass.saga@gmail.com>
+Masaki Matsushita                       <glass.saga@gmail.com> <glass@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# gogotanaka
+Kazuki Tanaka                           <gogotanaka@ruby-lang.org>
+Kazuki Tanaka                           <gogotanaka@ruby-lang.org> <gogotanaka@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# gotoken
+Kentaro Goto                            <gotoken@gmail.com>
+Kentaro Goto                            <gotoken@gmail.com> <gotoken@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# gotoyuzo
+GOTOU Yuuzou                            <gotoyuzo@notwork.org>
+GOTOU Yuuzou                            <gotoyuzo@notwork.org> <gotoyuzo@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# gsinclair
+Gavin Sinclair                          <gsinclair@soyabean.com.au>
+Gavin Sinclair                          <gsinclair@soyabean.com.au> <gsinclair@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# H_Konishi
+KONISHI Hiromasa                        <konishih@fd6.so-net.ne.jp>
+KONISHI Hiromasa                        <konishih@fd6.so-net.ne.jp> <H_Konishi@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# headius
+Charles Oliver Nutter                   <headius@headius.com>
+Charles Oliver Nutter                   <headius@headius.com> <headius@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# hone
+Terence Lee                             <hone@heroku.com>
+Terence Lee                             <hone@heroku.com> <hone@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# hsbt
+Hiroshi SHIBATA                         <hsbt@ruby-lang.org>
+Hiroshi SHIBATA                         <hsbt@ruby-lang.org> <hsbt@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# iwamatsu
+Nobuhiro Iwamatsu                       <iwamatsu@nigauri.org>
+Nobuhiro Iwamatsu                       <iwamatsu@nigauri.org> <iwamatsu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# jeg2
+James Edward Gray II                    <james@graysoftinc.com>
+James Edward Gray II                    <james@graysoftinc.com> <jeg2@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# jim
+Jim Weirich                             <jim@tardis.local>
+Jim Weirich                             <jim@tardis.local> <jim@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# k0kubun
+Takashi Kokubun                         <takashikkbn@gmail.com>
+Takashi Kokubun                         <takashikkbn@gmail.com> <k0kubun@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# kanemoto
+Yutaka Kanemoto                         <kanemoto@ruby-lang.org>
+Yutaka Kanemoto                         <kanemoto@ruby-lang.org> <kanemoto@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# katsu
+UENO Katsuhiro                          <katsu@blue.sky.or.jp>
+UENO Katsuhiro                          <katsu@blue.sky.or.jp> <katsu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# kazu
+Kazuhiro NISHIYAMA                      <zn@mbf.nifty.com>
+Kazuhiro NISHIYAMA                      <zn@mbf.nifty.com> <kazu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# keiju
+Keiju Ishitsuka                         <keiju@ishitsuka.com>
+Keiju Ishitsuka                         <keiju@ishitsuka.com> <keiju@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# knu
+Akinori MUSHA                           <knu@iDaemons.org>
+Akinori MUSHA                           <knu@iDaemons.org> <knu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ko1
+Koichi Sasada                           <ko1@atdot.net>
+Koichi Sasada                           <ko1@atdot.net> <ko1@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# kosaki
+KOSAKI Motohiro                         <kosaki.motohiro@gmail.com>
+KOSAKI Motohiro                         <kosaki.motohiro@gmail.com> <kosaki@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# kosako
+K.Kosako                                <sndgk393@ybb.ne.jp>
+K.Kosako                                <sndgk393@ybb.ne.jp> <kosako@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# kou
+Sutou Kouhei                            <kou@clear-code.com>
+Sutou Kouhei                            <kou@clear-code.com> <kou@cozmixng.org>
+Sutou Kouhei                            <kou@clear-code.com> <kou@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# kouji
+Kouji Takao                             <kouji.takao@gmail.com>
+Kouji Takao                             <kouji.takao@gmail.com> <kouji@takao7.net>
+Kouji Takao                             <kouji.takao@gmail.com> <kouji@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ksaito
+Kazuo Saito                             <ksaito@uranus.dti.ne.jp>
+Kazuo Saito                             <ksaito@uranus.dti.ne.jp> <ksaito@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ktsj
+Kazuki Tsujimoto                        <kazuki@callcc.net>
+Kazuki Tsujimoto                        <kazuki@callcc.net> <ktsj@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# luislavena
+Luis Lavena                             <luislavena@gmail.com>
+Luis Lavena                             <luislavena@gmail.com> <luislavena@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# mame
+Yusuke Endoh                            <mame@ruby-lang.org>
+## Yusuke Endoh                         <mame@ruby-lang.org> <mame@tsg.ne.jp>
+Yusuke Endoh                            <mame@ruby-lang.org> <mame@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# marcandre
+Marc-Andre Lafortune                    <github@marc-andre.ca>
+Marc-Andre Lafortune                    <ruby-core@marc-andre.ca>
+Marc-Andre Lafortune                    <ruby-core@marc-andre.ca> <marcandre@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# matz
+Yukihiro "Matz" Matsumoto               <matz@ruby.or.jp>
+Yukihiro "Matz" Matsumoto               <matz@ruby.or.jp> <matz@ruby-lang.org>
+Yukihiro "Matz" Matsumoto               <matz@ruby.or.jp> <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# michal
+Michal Rokos                            <michal@ruby-lang.org>
+Michal Rokos                            <michal@ruby-lang.org> <michal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# mneumann
+Michael Neumann                         <mneumann@ruby-lang.org>
+Michael Neumann                         <mneumann@ruby-lang.org> <mneumann@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# mrkn
+Kenta Murata                            <mrkn@mrkn.jp>
+Kenta Murata                            <mrkn@mrkn.jp> <muraken@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+Kenta Murata                            <mrkn@mrkn.jp> <3959+mrkn@users.noreply.github.com>
+Kenta Murata                            <mrkn@mrkn.jp> <mrkn@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# nagachika
+nagachika                               <nagachika@ruby-lang.org>
+nagachika                               <nagachika@ruby-lang.org> <nagachika@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# nagai
+Hidetoshi NAGAI                         <nagai@ai.kyutech.ac.jp>
+Hidetoshi NAGAI                         <nagai@ai.kyutech.ac.jp> <nagai@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# nahi
+Hiroshi Nakamura                        <nahi@ruby-lang.org>
+Hiroshi Nakamura                        <nahi@ruby-lang.org> <nahi@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# nari
+Narihiro Nakamura                       <authornari@gmail.com>
+Narihiro Nakamura                       <authornari@gmail.com> <nari@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# naruse
+NARUSE, Yui                             <naruse@airemix.jp>
+NARUSE, Yui                             <naruse@airemix.jp> <naruse@ruby-lang.org>
+NARUSE, Yui                             <naruse@airemix.jp> <naruse@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ngoto
+Naohisa Goto                            <ngotogenome@gmail.com>
+Naohisa Goto                            <ngotogenome@gmail.com> <ngoto@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# nobu
+Nobuyoshi Nakada                        <nobu@ruby-lang.org>
+Nobuyoshi Nakada                        <nobu@ruby-lang.org> <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# normal
+Eric Wong                               <normal@ruby-lang.org>
+Eric Wong                               <normal@ruby-lang.org> <e@80x24.org>
+Eric Wong                               <normal@ruby-lang.org> <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ntalbott
+Nathaniel Talbott                       <ntalbott@ruby-lang.org>
+Nathaniel Talbott                       <ntalbott@ruby-lang.org> <ntalbott@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ocean
+Hirokazu Yamamoto                       <ocean@m2.ccsnet.ne.jp>
+Hirokazu Yamamoto                       <ocean@m2.ccsnet.ne.jp> <ocean@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# odaira
+Rei Odaira                              <rodaira@us.ibm.com>
+Rei Odaira                              <rodaira@us.ibm.com> <Rei.Odaira@gmail.com>
+Rei Odaira                              <rodaira@us.ibm.com> <odaira@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# okkez
+okkez                                   <okkez000@gmail.com>
+okkez                                   <okkez000@gmail.com> <okkez@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# rhe
+Kazuki Yamaguchi                        <k@rhe.jp>
+Kazuki Yamaguchi                        <k@rhe.jp> <rhe@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ryan
+Ryan Davis                              <ryand-github@zenspider.com>
+Ryan Davis                              <ryand-github@zenspider.com> <ryand-ruby@zenspider.com>
+Ryan Davis                              <ryand-github@zenspider.com> <ryan@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# samuel
+Samuel Williams                         <samuel.williams@oriontransfer.co.nz>
+Samuel Williams                         <samuel.williams@oriontransfer.co.nz> <samuel@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# seki
+Masatoshi SEKI                          <m_seki@mva.biglobe.ne.jp>
+Masatoshi SEKI                          <m_seki@mva.biglobe.ne.jp> <seki@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ser
+Sean Russell                            <ser@germane-software.com>
+Sean Russell                            <ser@germane-software.com> <ser@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# shigek
+Shigeo Kobayashi                        <shigek@ruby-lang.org>
+Shigeo Kobayashi                        <shigek@ruby-lang.org> <shigek@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# shirosaki
+Hiroshi Shirosaki                       <h.shirosaki@gmail.com>
+Hiroshi Shirosaki                       <h.shirosaki@gmail.com> <shirosaki@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# sho-h
+Sho Hashimoto                           <sho-h@ruby-lang.org>
+Sho Hashimoto                           <sho-h@ruby-lang.org> <sho-h@netlab.jp>
+Sho Hashimoto                           <sho-h@ruby-lang.org> <sho.hsmt@gmail.com>
+Sho Hashimoto                           <sho-h@ruby-lang.org> <sho-h@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# shugo
+Shugo Maeda                             <shugo@ruby-lang.org>
+Shugo Maeda                             <shugo@ruby-lang.org> <shugo@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# shyouhei
+卜部昌平                                    <shyouhei@ruby-lang.org>
+卜部昌平                                    <shyouhei@ruby-lang.org> <shyouhei@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# siena
+Siena.                                  <siena@faculty.chiba-u.jp>
+Siena.                                  <siena@faculty.chiba-u.jp> <siena@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# sonots
+sonots                                  <sonots@gmail.com>
+sonots                                  <sonots@gmail.com> <sonots@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# sorah
+Sorah Fukumori                          <her@sorah.jp>
+Sorah Fukumori                          <her@sorah.jp> <sorah@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# stomar
+Marcus Stollsteimer                     <sto.mar@web.de>
+Marcus Stollsteimer                     <sto.mar@web.de> <stomar@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# suke
+Masaki Suketa                           <masaki.suketa@nifty.ne.jp>
+Masaki Suketa                           <masaki.suketa@nifty.ne.jp> <suke@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# tadd
+Tadashi Saito                           <tad.a.digger@gmail.com>
+Tadashi Saito                           <tad.a.digger@gmail.com> <tadd@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# tadf
+Tadayoshi Funaba                        <tadf@dotrb.org>
+Tadayoshi Funaba                        <tadf@dotrb.org> <tadf@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# takano32
+TAKANO Mitsuhiro                        <takano32@gmail.com>
+TAKANO Mitsuhiro                        <takano32@gmail.com> <takano32@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# tarui
+Masaya Tarui                            <tarui@ruby-lang.org>
+Masaya Tarui                            <tarui@ruby-lang.org> <tarui@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# technorama
+Technorama Ltd.                         <oss-ruby@technorama.net>
+Technorama Ltd.                         <oss-ruby@technorama.net> <technorama@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# tenderlove
+Aaron Patterson                         <tenderlove@ruby-lang.org>
+Aaron Patterson                         <tenderlove@ruby-lang.org> <tenderlove@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# tmm1
+Aman Gupta                              <ruby@tmm1.net>
+Aman Gupta                              <ruby@tmm1.net> <tmm1@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ts
+Guy Decoux                              <ts@moulon.inra.fr>
+Guy Decoux                              <ts@moulon.inra.fr> <ts@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# ttate
+Takaaki Tateishi                        <ttate@ttsky.net>
+## Takaaki Tateishi                     <ttate@ttsky.net> <ttate@kt.jaist.ac.jp>
+Takaaki Tateishi                        <ttate@ttsky.net> <ttate@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# uema2
+Takaaki Uematsu                         <uema2x@jcom.home.ne.jp>
+Takaaki Uematsu                         <uema2x@jcom.home.ne.jp> <uema2@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# usa
+U.Nakamura                              <usa@ruby-lang.org>
+U.Nakamura                              <usa@ruby-lang.org> <usa@garbagecollect.jp>
+U.Nakamura                              <usa@ruby-lang.org> <usa@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# wakou
+Wakou Aoyama                            <wakou@ruby-lang.org>
+Wakou Aoyama                            <wakou@ruby-lang.org> <wakou@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# wanabe
+wanabe                                  <s.wanabe@gmail.com>
+wanabe                                  <s.wanabe@gmail.com> <wanabe@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# watson1978
+Watson                                  <watson1978@gmail.com>
+Watson                                  <watson1978@gmail.com> <watson1978@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# wew
+William Webber                          <william@williamwebber.com>
+William Webber                          <william@williamwebber.com> <wew@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# why
+why the lucky stiff                     <why@ruby-lang.org>
+why the lucky stiff                     <why@ruby-lang.org> <why@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# xibbar
+Takeyuki FUJIOKA                        <xibbar@ruby-lang.org>
+Takeyuki FUJIOKA                        <xibbar@ruby-lang.org> <xibbar@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# yugui
+Yuki Yugui Sonoda                       <yugui@yugui.jp>
+Yuki Yugui Sonoda                       <yugui@yugui.jp> <yugui@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# yui-knk
+yui-knk                                 <spiketeika@gmail.com>
+yui-knk                                 <spiketeika@gmail.com> <yui-knk@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# yuki
+Yuki Nishijima                          <yuki24@hey.com>
+Yuki Nishijima                          <yuki24@hey.com> <mail@yukinishijima.net>
+Yuki Nishijima                          <yuki24@hey.com> <yuki@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# zsombor
+Dee Zsombor                             <zsombor@ruby-lang.org>
+Dee Zsombor                             <zsombor@ruby-lang.org> <zsombor@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
+
+# zzak
+zzak                                    <zzakscott@gmail.com>
+zzak                                    <zzakscott@gmail.com> <zzak@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
diff --git a/.rdoc_options b/.rdoc_options
index 760507c7a2..89265cafd4 100644
--- a/.rdoc_options
+++ b/.rdoc_options
@@ -1,4 +1,39 @@
 ---
 page_dir: doc
-main_page: README.md
+charset: UTF-8
+encoding: UTF-8
+main_page: index.md
 title: Documentation for Ruby development version
+visibility: :private
+rdoc_include:
+- doc
+
+exclude:
+- \.gemspec\z
+- lib/set/subclass_compatible.rb
+
+autolink_excluded_words:
+- Box
+- Class
+- Method
+- Module
+- Process
+- RDoc
+- Ruby
+- Set
+- ZJIT
+- YJIT
+
+canonical_root: https://docs.ruby-lang.org/en/master
+
+footer_content:
+  Ruby:
+    Documentation: index.html
+    Official Website: https://www.ruby-lang.org/
+    Playground: https://ruby.github.io/play-ruby/
+  Resources:
+    GitHub: https://github.com/ruby/ruby
+    Issue Tracker: https://bugs.ruby-lang.org/projects/ruby-master/issues
+    RubyGems: https://rubygems.org/
+  Community:
+    X: https://x.com/rubylangorg
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 665feba914..0000000000
--- a/.travis.yml
+++ /dev/null
@@ -1,235 +0,0 @@
-# -*- YAML -*-
-# Copyright (C) 2011 Urabe, Shyouhei.  All rights reserved.
-#
-# This file is  a part of the programming language  Ruby.  Permission is hereby
-# granted,  to either  redistribute  or  modify this  file,  provided that  the
-# conditions  mentioned in  the file  COPYING are  met.  Consult  the  file for
-# details.
-
-# We only manage non-amd64 free pipelines.
-# https://docs.travis-ci.com/user/billing-overview/
-
-language: c
-
-os: linux
-
-if: commit_message !~ /\[DOC\]/
-
-dist: focal
-
-git:
-  quiet: true
-
-cache:
-  ccache: true
-  directories:
-    - $HOME/config_2nd
-    - $HOME/.downloaded-cache
-
-env:
-  global:
-    # The tests skipped in `make test-all`.
-    - TEST_ALL_SKIPPED_TESTS=
-    # The tests executed separately by `make test-all`.
-    - TEST_ALL_SEPARATED_TESTS=
-    # Reset timestamps early
-    - _=$(touch NEWS && find . -type f -exec touch -r NEWS {} +)
-    - CONFIGURE_TTY=no
-    - CCACHE_COMPILERCHECK=none
-    - CCACHE_NOCOMPRESS=1
-    - CCACHE_MAXSIZE=512Mi
-    - NPROC="`nproc`"
-    # JOBS and SETARCH are overridden when necessary; see below.
-    - JOBS=-j$((1+${NPROC}))
-    - SETARCH=
-    - RUBY_PREFIX=/tmp/ruby-prefix
-    - GEMS_FOR_TEST='timezone tzinfo'
-    # https://github.com/travis-ci/travis-build/blob/e411371dda21430a60f61b8f3f57943d2fe4d344/lib/travis/build/bash/travis_apt_get_options.bash#L7
-    - travis_apt_get_options='--allow-downgrades --allow-remove-essential --allow-change-held-packages'
-    - travis_apt_get_options="-yq --no-install-suggests --no-install-recommends $travis_apt_get_options"
-    # -O1 is faster than -O3 in our tests.
-    - optflags=-O1
-    # -g0 disables backtraces when SEGV.  Do not set that.
-    - debugflags=-ggdb3
-
-.org.ruby-lang.ci.matrix-definitions:
-
-  - &gcc-10
-    compiler: gcc-10
-    before_install:
-      - tool/travis_retry.sh sudo bash -c "rm -rf '${TRAVIS_ROOT}/var/lib/apt/lists/'* && exec apt-get update -yq"
-      - >-
-        tool/travis_retry.sh sudo -E apt-get $travis_apt_get_options install
-        ccache
-        gcc-10
-        g++-10
-        libffi-dev
-        libncurses-dev
-        libncursesw5-dev
-        libreadline-dev
-        libssl-dev
-        libyaml-dev
-        openssl
-        zlib1g-dev
-
-  # --------
-
-  - &arm64-linux
-    name: arm64-linux
-    arch: arm64
-    <<: *gcc-10
-
-  - &ppc64le-linux
-    name: ppc64le-linux
-    arch: ppc64le
-    <<: *gcc-10
-
-  - &s390x-linux
-    name: s390x-linux
-    arch: s390x
-    <<: *gcc-10
-
-  - &arm32-linux
-    name: arm32-linux
-    arch: arm64
-    # https://packages.ubuntu.com/focal/crossbuild-essential-armhf
-    compiler: arm-linux-gnueabihf-gcc
-    env:
-      - SETARCH='setarch linux32 --verbose --32bit'
-      # The "TestReadline#test_interrupt_in_other_thread" started failing on arm32
-      # from https://www.travis-ci.com/github/ruby/ruby/jobs/529005145
-      - TEST_ALL_SKIPPED_TESTS=test_interrupt_in_other_thread
-    before_install:
-      - sudo dpkg --add-architecture armhf
-      - tool/travis_retry.sh sudo bash -c "rm -rf '${TRAVIS_ROOT}/var/lib/apt/lists/'* && exec apt-get update -yq"
-      - >-
-        tool/travis_retry.sh sudo -E apt-get $travis_apt_get_options install
-        ccache
-        crossbuild-essential-armhf
-        libc6:armhf
-        libstdc++-10-dev:armhf
-        libffi-dev:armhf
-        libncurses-dev:armhf
-        libncursesw5-dev:armhf
-        libreadline-dev:armhf
-        libssl-dev:armhf
-        libyaml-dev:armhf
-        linux-libc-dev:armhf
-        zlib1g-dev:armhf
-
-matrix:
-  include:
-    # Build every commit (Allowed Failures):
-    - <<: *arm32-linux
-    # Comment out as the 2nd arm64 pipeline is unstable.
-    # - <<: *arm64-linux
-    - <<: *ppc64le-linux
-    - <<: *s390x-linux
-  allow_failures:
-    # We see multiple errors indicating errors on the Travis environment itself in a short while:
-    # https://app.travis-ci.com/github/ruby/ruby/jobs/544382885
-    # https://app.travis-ci.com/github/ruby/ruby/jobs/544361370
-    # It's not a fault of Ruby's arm32 support but just Travis arm32 seems unsable.
-    - name: arm32-linux
-    # - name: arm64-linux
-    # We see "Some worker was crashed." in about 40% of recent ppc64le-linux jobs
-    # e.g. https://app.travis-ci.com/github/ruby/ruby/jobs/530959548
-    - name: ppc64le-linux
-    # Tentatively disable, because often hungs up **after** all tests
-    # have finished successfully and saving caches.
-    - name: s390x-linux
-  fast_finish: true
-
-before_script:
-  - . tool/ci_functions.sh
-  - |-
-    if [ -n "${TEST_ALL_SKIPPED_TESTS}" ]; then
-      TEST_ALL_OPTS="${TEST_ALL_OPTS} $(ci_to_excluded_test_opts "${TEST_ALL_SKIPPED_TESTS}")"
-      if [ -z "${TEST_ALL_SEPARATED_TESTS}" ]; then
-        TEST_ALL_SEPARATED_TESTS="${TEST_ALL_SKIPPED_TESTS}"
-      fi
-    fi
-  - |-
-    if [ -n "${TEST_ALL_SEPARATED_TESTS}" ]; then
-      TEST_ALL_OPTS_SEPARATED="$(ci_to_included_test_opts "${TEST_ALL_SEPARATED_TESTS}")"
-    fi
-  - echo TEST_ALL_OPTS="${TEST_ALL_OPTS}" TEST_ALL_OPTS_SEPARATED="${TEST_ALL_OPTS_SEPARATED}"
-  - rm -fr .ext autom4te.cache
-  - |-
-    [ -d ~/.downloaded-cache ] ||
-    mkdir ~/.downloaded-cache
-  - ln -s ~/.downloaded-cache
-  - "> config.status"
-  - "> .rbconfig.time"
-  - sed -f tool/prereq.status template/Makefile.in common.mk > Makefile
-  - make -s $JOBS up
-  - make -s $JOBS srcs
-  - rm -f config.status Makefile rbconfig.rb .rbconfig.time
-  - |-
-    if [ -d ~/config_2nd ]; then
-      cp -pr ~/config_2nd build
-    else
-      mkdir build
-    fi
-  - mkdir config_1st config_2nd gems/src
-  - chmod -R a-w .
-  - chmod -R u+w build config_1st config_2nd gems/src
-  - cd build
-  - |-
-    case "$CC" in
-    gcc*)   CC="ccache $CC${GCC_FLAGS:+ }$GCC_FLAGS -fno-diagnostics-color";;
-    clang*) CC="ccache $CC${GCC_FLAGS:+ }$GCC_FLAGS -fno-color-diagnostics";;
-    esac
-  - |-
-    [ ! -f config.cache ] ||
-    [ "$CC" = "`sed -n s/^ac_cv_prog_CC=//p config.cache`" ] ||
-    (set -x; exec rm config.cache)
-  - $SETARCH ../configure -C --disable-install-doc --prefix=$RUBY_PREFIX $CONFIG_FLAG
-  - cp -pr config.cache config.status .ext/include ../config_1st
-  - $SETARCH make reconfig
-  - cp -pr config.cache config.status .ext/include ../config_2nd
-  - (cd .. && exec diff -ru config_1st config_2nd)
-  - chmod u+w ..
-  - rm -rf ~/config_2nd
-  - mv ../config_2nd ~
-  - chmod u-w ..
-  - $SETARCH make -s $JOBS
-  - make -s install
-  - |-
-    [ -z "${GEMS_FOR_TEST}" ] ||
-    $RUBY_PREFIX/bin/gem install --no-document $GEMS_FOR_TEST
-  - echo "raise 'do not load ~/.irbrc in test'" > ~/.irbrc
-
-script:
-  - $SETARCH make -s test -o showflags TESTOPTS="${TESTOPTS=$JOBS -q --tty=no}"
-  - ../tool/travis_wait.sh $SETARCH make -s test-all -o exts TESTOPTS="$JOBS -q --tty=no ${TEST_ALL_OPTS}" RUBYOPT="-w"
-  # Run the failing tests separately returning ok status to check if it works,
-  # visualize them.
-  - |
-    if [ -n "${TEST_ALL_OPTS_SEPARATED}" ]; then
-      $SETARCH make -s test-all -o exts TESTOPTS="$JOBS -v --tty=no ${TEST_ALL_OPTS_SEPARATED}" RUBYOPT="-w" || :
-    fi
-  - $SETARCH make -s test-spec MSPECOPT=-ff # not using `-j` because sometimes `mspec -j` silently dies
-  - $SETARCH make -s -o showflags leaked-globals
-
-# We enable Travis on the specific branches or forked repositories here.
-if: (repo = ruby/ruby AND (branch = master OR branch =~ /^ruby_\d_\d$/)) OR repo != ruby/ruby
-
-# We want to be notified when something happens.
-notifications:
-  irc:
-    channels:
-      - "chat.freenode.net#ruby-core"
-    on_success: change # [always|never|change] # default: always
-    on_failure: always # [always|never|change] # default: always
-    template:
-      - "%{message} by @%{author}: See %{build_url}"
-
-  webhooks:
-    urls:
-      - secure: mRsoS/UbqDkKkW5p3AEqM27d4SZnV6Gsylo3bm8T/deltQzTsGzZwrm7OIBXZv0UFZdE68XmPlyHfZFLSP2V9QZ7apXMf9/vw0GtcSe1gchtnjpAPF6lYBn7nMCbVPPx9cS0dwL927fjdRM1vj7IKZ2bk4F0lAJ25R25S6teqdk= # ruby-lang slack: ruby/simpler-alerts-bot (travis)
-    on_success: never
-    on_failure: always
-
-  email:
-    - jaruga@ruby-lang.org
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 13df6087ca..35e79dd3b9 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1 +1 @@
-See ["Contributing to Ruby"](https://docs.ruby-lang.org/en/master/contributing_md.html), which includes setup and build instructions.
+See ["Contributing to Ruby"](https://docs.ruby-lang.org/en/master/contributing/contributing_md.html), which includes setup and build instructions.
diff --git a/COPYING b/COPYING
index 48e5a96de7..428ce03ed7 100644
--- a/COPYING
+++ b/COPYING
@@ -1,3 +1,5 @@
+{日本語}[rdoc-ref:COPYING.ja]
+
 Ruby is copyrighted free software by Yukihiro Matsumoto <matz@netlab.jp>.
 You can redistribute it and/or modify it under either the terms of the
 2-clause BSDL (see the file BSDL), or the conditions below:
diff --git a/COPYING.ja b/COPYING.ja
index 230376bc60..5de2dbcc8f 100644
--- a/COPYING.ja
+++ b/COPYING.ja
@@ -1,3 +1,5 @@
+{English}[rdoc-ref:COPYING]
+
 本プログラムはフリーソフトウェアです．2-clause BSDL
 または以下に示す条件で本プログラムを再配布できます
 2-clause BSDLについてはBSDLファイルを参照して下さい．
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000000..9a4b2ebbba
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,193 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "capstone"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "015ef5d5ca1743e3f94af9509ba6bd2886523cfee46e48d15c2ef5216fd4ac9a"
+dependencies = [
+ "capstone-sys",
+ "libc",
+]
+
+[[package]]
+name = "capstone-sys"
+version = "0.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2267cb8d16a1e4197863ec4284ffd1aec26fe7e57c58af46b02590a0235809a0"
+dependencies = [
+ "cc",
+ "libc",
+]
+
+[[package]]
+name = "cc"
+version = "1.2.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "525046617d8376e3db1deffb079e91cef90a89fc3ca5c185bbf8c9ecdd15cd5c"
+dependencies = [
+ "shlex",
+]
+
+[[package]]
+name = "console"
+version = "0.15.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0e1f83fc076bd6dd27517eacdf25fef6c4dfe5f1d7448bafaaf3a26f13b5e4eb"
+dependencies = [
+ "encode_unicode",
+ "lazy_static",
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
+name = "encode_unicode"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a357d28ed41a50f9c765dbfe56cbc04a64e53e5fc58ba79fbc34c10ef3df831f"
+
+[[package]]
+name = "insta"
+version = "1.43.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "154934ea70c58054b556dd430b99a98c2a7ff5309ac9891597e339b5c28f4371"
+dependencies = [
+ "console",
+ "once_cell",
+ "similar",
+]
+
+[[package]]
+name = "jit"
+version = "0.1.0"
+
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
+[[package]]
+name = "libc"
+version = "0.2.171"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c19937216e9d3aa9956d9bb8dfc0b0c8beb6058fc4f7a4dc4d850edf86a237d6"
+
+[[package]]
+name = "once_cell"
+version = "1.21.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42f5e15c9953c5e4ccceeb2e7382a716482c34515315f7b03532b8b4e8393d2d"
+
+[[package]]
+name = "ruby"
+version = "0.0.0"
+dependencies = [
+ "yjit",
+ "zjit",
+]
+
+[[package]]
+name = "shlex"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
+
+[[package]]
+name = "similar"
+version = "2.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32fea41aca09ee824cc9724996433064c89f7777e60762749a4170a14abbfa21"
+
+[[package]]
+name = "windows-sys"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
+dependencies = [
+ "windows-targets",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
+
+[[package]]
+name = "yjit"
+version = "0.1.0"
+dependencies = [
+ "capstone",
+ "jit",
+]
+
+[[package]]
+name = "zjit"
+version = "0.0.1"
+dependencies = [
+ "capstone",
+ "insta",
+ "jit",
+]
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000000..521129d92d
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,60 @@
+# This is the root Cargo [workspace](https://doc.rust-lang.org/cargo/reference/workspaces.html)
+# and the root package for all the rust code that are statically linked into ruby. Rust tooling
+# limitations means all Rust code need to share a single archive library (staticlib) at the
+# integration point with non-rust code. (See rustlang/rust#44322 and #104707 for a taste of
+# the linking challenges.)
+#
+# Do not add required dependencies. This is a policy that helps downstream consumers and give
+# us tight control over what we ship. All of the optional dependencies are used exclusively
+# during development.
+#
+# Release builds avoid Cargo entirely because offline builds can fail even when none of the
+# optional dependencies are built (rust-lang/cargo#10352).
+
+[workspace]
+members = ["zjit", "yjit", "jit"]
+
+[package]
+name = "ruby"
+version = "0.0.0"
+edition = "2024"
+rust-version = "1.85.0"
+publish = false # Don't publish to crates.io
+
+[dependencies]
+yjit = { path = "yjit", optional = true }
+zjit = { path = "zjit", optional = true }
+
+[lib]
+crate-type = ["staticlib"]
+path = "ruby.rs"
+
+[features]
+disasm = ["yjit?/disasm", "zjit?/disasm"]
+runtime_checks = ["yjit?/runtime_checks", "zjit?/runtime_checks"]
+yjit = [ "dep:yjit" ]
+zjit = [ "dep:zjit" ]
+
+[profile.dev]
+opt-level = 0
+debug = true
+debug-assertions = true
+overflow-checks = true
+
+[profile.dev_nodebug]
+inherits = "dev"
+
+[profile.stats]
+inherits = "release"
+
+[profile.release]
+# NOTE: --enable-yjit and zjit builds use `rustc` without going through Cargo. You
+# might want to update the `rustc` invocation if you change this profile.
+opt-level = 3
+# The extra robustness that comes from checking for arithmetic overflow is
+# worth the performance cost for the compiler.
+overflow-checks = true
+# Generate debug info
+debug = true
+# Use ThinLTO. Much smaller output for a small amount of build time increase.
+lto = "thin"
diff --git a/LEGAL b/LEGAL
index 9645728efe..2777aa2c14 100644
--- a/LEGAL
+++ b/LEGAL
@@ -58,12 +58,12 @@ mentioned below.
 
 [ccan/list/list.h]
 
-  This file is licensed under the {MIT License}[rdoc-label:label-MIT+License].
+  This file is licensed under the {MIT License}[rdoc-ref:@MIT+License].
 
 [coroutine]
 
   Unless otherwise specified, these files are licensed under the
-  {MIT License}[rdoc-label:label-MIT+License].
+  {MIT License}[rdoc-ref:@MIT+License].
 
 [include/ruby/onigmo.h]
 [include/ruby/oniguruma.h]
@@ -546,7 +546,7 @@ mentioned below.
 
 [vsnprintf.c]
 
-  This file is under the {old-style BSD license}[rdoc-label:label-Old-style+BSD+license].
+  This file is under the {old-style BSD license}[rdoc-ref:@Old-style+BSD+license].
 
   >>>
     Copyright (c) 1990, 1993::
@@ -577,7 +577,7 @@ mentioned below.
 
 [missing/crypt.c]
 
-  This file is under the {old-style BSD license}[rdoc-label:label-Old-style+BSD+license].
+  This file is under the {old-style BSD license}[rdoc-ref:@Old-style+BSD+license].
 
   >>>
     Copyright (c) 1989, 1993::
@@ -588,7 +588,7 @@ mentioned below.
 
 [missing/setproctitle.c]
 
-  This file is under the {old-style BSD license}[rdoc-label:label-Old-style+BSD+license].
+  This file is under the {old-style BSD license}[rdoc-ref:@Old-style+BSD+license].
 
   >>>
     Copyright 2003:: Damien Miller
@@ -702,54 +702,27 @@ mentioned below.
     OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     SUCH DAMAGE.
 
-[ext/json/generator/generator.c]
+[ext/json/vendor/fpconv.c]
 
-  The file contains the following copyright notice.
+  This file is under the {Boost Software License}[rdoc-ref:@Boost+Software+License+1.0].
 
-  >>>
-    Copyright 2001-2004:: Unicode, Inc.
-
-    Disclaimer::
-
-      This source code is provided as is by Unicode, Inc. No claims are
-      made as to fitness for any particular purpose. No warranties of any
-      kind are expressed or implied. The recipient agrees to determine
-      applicability of information provided. If this file has been
-      purchased on magnetic or optical media from Unicode, Inc., the
-      sole remedy for any claim will be exchange of defective media
-      within 90 days of receipt.
-
-    Limitations on Rights to Redistribute This Code::
-
-      Unicode, Inc. hereby grants the right to freely use the information
-      supplied in this file in the creation of products supporting the
-      Unicode Standard, and to make copies of this file in any form
-      for internal or external distribution as long as this notice
-      remains attached.
-
-[ext/nkf/nkf-utf8/config.h]
-[ext/nkf/nkf-utf8/nkf.c]
-[ext/nkf/nkf-utf8/utf8tbl.c]
-
-  These files are under the following license.  So to speak, it is
-  copyrighted semi-public-domain software.
+[ext/json/vendor/jeaiii-ltoa.h]
 
   >>>
-    Copyright (C) 1987:: Fujitsu LTD. (Itaru ICHIKAWA)
+    Copyright (c) 2024,2025 Enrico Thierbach - https://github.com/radiospiel
+    Copyright (c) 2022 James Edward Anhalt III - https://github.com/jeaiii/itoa
+
+    {MIT License}[rdoc-ref:@MIT+License]
 
-    Everyone is permitted to do anything on this program
-    including copying, modifying, improving,
-    as long as you don't try to pretend that you wrote it.
-    i.e., the above copyright notice has to appear in all copies.
-    Binary distribution requires original version messages.
-    You don't have to ask before copying, redistribution or publishing.
-    THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE.
+[ext/json/vendor/ryu.h]
+  This file is adapted from the Ryu algorithm by Ulf Adams https://github.com/ulfjack/ryu.
+  It is dual-licensed under {Apache License 2.0}[rdoc-ref:@Apache+License+2.0] OR
+  {Boost Software License 1.0}[rdoc-ref:@Boost+Software+License+1.0].
 
 [ext/psych]
 [test/psych]
 
-  The files under these directories are under the following license, except for
-  ext/psych/yaml.
+  The files under these directories are under the following license.
 
   >>>
     Copyright 2009:: Aaron Patterson, et al.
@@ -772,31 +745,6 @@ mentioned below.
     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     SOFTWARE.
 
-[ext/psych/yaml]
-
-  The files under this directory are under the following license.
-
-  >>>
-    Copyright (c) 2006:: Kirill Simonov
-
-    Permission is hereby granted, free of charge, to any person obtaining a copy of
-    this software and associated documentation files (the "Software"), to deal in
-    the Software without restriction, including without limitation the rights to
-    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
-    of the Software, and to permit persons to whom the Software is furnished to do
-    so, subject to the following conditions:
-
-    The above copyright notice and this permission notice shall be included in all
-    copies or substantial portions of the Software.
-
-    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-    SOFTWARE.
-
 [ext/pty/pty.c]
 
   >>>
@@ -905,7 +853,7 @@ mentioned below.
   >>>
     RubyGems is copyrighted free software by Chad Fowler, Rich Kilmer, Jim
     Weirich and others.  You can redistribute it and/or modify it under
-    either the terms of the {MIT license}[rdoc-label:label-MIT+License], or the conditions
+    either the terms of the {MIT license}[rdoc-ref:@MIT+License], or the conditions
     below:
 
     1. You may make and give away verbatim copies of the source form of the
@@ -967,7 +915,7 @@ mentioned below.
     Portions copyright (c) 2010:: Andre Arko
     Portions copyright (c) 2009:: Engine Yard
 
-    {MIT License}[rdoc-label:label-MIT+License]
+    {MIT License}[rdoc-ref:@MIT+License]
 
 [lib/bundler/vendor/thor]
 
@@ -976,17 +924,25 @@ mentioned below.
   >>>
     Copyright (c) 2008 Yehuda Katz, Eric Hodel, et al.
 
-    {MIT License}[rdoc-label:label-MIT+License]
+    {MIT License}[rdoc-ref:@MIT+License]
 
-[lib/rubygems/resolver/molinillo]
-[lib/bundler/vendor/molinillo]
+[lib/rubygems/vendor/molinillo]
 
   molinillo is under the following license.
 
   >>>
     Copyright (c) 2014 Samuel E. Giddins segiddins@segiddins.me
 
-    {MIT License}[rdoc-label:label-MIT+License]
+    {MIT License}[rdoc-ref:@MIT+License]
+
+[lib/bundler/vendor/pub_grub]
+
+  pub_grub is under the following license.
+
+  >>>
+    Copyright (c) 2018 John Hawthorn
+
+    {MIT License}[rdoc-ref:@MIT+License]
 
 [lib/bundler/vendor/connection_pool]
 
@@ -995,7 +951,7 @@ mentioned below.
   >>>
     Copyright (c) 2011 Mike Perham
 
-    {MIT License}[rdoc-label:label-MIT+License]
+    {MIT License}[rdoc-ref:@MIT+License]
 
 [lib/bundler/vendor/net-http-persistent]
 
@@ -1004,7 +960,7 @@ mentioned below.
   >>>
     Copyright (c) Eric Hodel, Aaron Patterson
 
-    {MIT License}[rdoc-label:label-MIT+License]
+    {MIT License}[rdoc-ref:@MIT+License]
 
 [lib/did_you_mean]
 [lib/did_you_mean.rb]
@@ -1015,7 +971,7 @@ mentioned below.
   >>>
     Copyright (c) 2014-2016 Yuki Nishijima
 
-    {MIT License}[rdoc-label:label-MIT+License]
+    {MIT License}[rdoc-ref:@MIT+License]
 
 [lib/error_highlight]
 [lib/error_highlight.rb]
@@ -1026,7 +982,7 @@ mentioned below.
   >>>
     Copyright (c) 2021 Yusuke Endoh
 
-    {MIT License}[rdoc-label:label-MIT+License]
+    {MIT License}[rdoc-ref:@MIT+License]
 
 [benchmark/so_ackermann.rb]
 [benchmark/so_array.rb]
@@ -1109,3 +1065,236 @@ mentioned below.
 
       From ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change
       paragraph 3 above is now null and void.
+
+== Boost Software License 1.0
+
+>>>
+      Boost Software License - Version 1.0 - August 17th, 2003
+
+      Permission is hereby granted, free of charge, to any person or organization
+      obtaining a copy of the software and accompanying documentation covered by
+      this license (the "Software") to use, reproduce, display, distribute,
+      execute, and transmit the Software, and to prepare derivative works of the
+      Software, and to permit third-parties to whom the Software is furnished to
+      do so, all subject to the following:
+
+      The copyright notices in the Software and this entire statement, including
+      the above license grant, this restriction and the following disclaimer,
+      must be included in all copies of the Software, in whole or in part, and
+      all derivative works of the Software, unless such copies or derivative
+      works are solely in the form of machine-executable object code generated by
+      a source language processor.
+
+      THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+      IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+      FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+      SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+      FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+      ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+      DEALINGS IN THE SOFTWARE.
+
+== Apache License 2.0
+
+>>>
+      Apache License
+      Version 2.0, January 2004
+      http://www.apache.org/licenses/
+
+      TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+      1. Definitions.
+
+         "License" shall mean the terms and conditions for use, reproduction,
+         and distribution as defined by Sections 1 through 9 of this document.
+
+         "Licensor" shall mean the copyright owner or entity authorized by
+         the copyright owner that is granting the License.
+
+         "Legal Entity" shall mean the union of the acting entity and all
+         other entities that control, are controlled by, or are under common
+         control with that entity. For the purposes of this definition,
+         "control" means (i) the power, direct or indirect, to cause the
+         direction or management of such entity, whether by contract or
+         otherwise, or (ii) ownership of fifty percent (50%) or more of the
+         outstanding shares, or (iii) beneficial ownership of such entity.
+
+         "You" (or "Your") shall mean an individual or Legal Entity
+         exercising permissions granted by this License.
+
+         "Source" form shall mean the preferred form for making modifications,
+         including but not limited to software source code, documentation
+         source, and configuration files.
+
+         "Object" form shall mean any form resulting from mechanical
+         transformation or translation of a Source form, including but
+         not limited to compiled object code, generated documentation,
+         and conversions to other media types.
+
+         "Work" shall mean the work of authorship, whether in Source or
+         Object form, made available under the License, as indicated by a
+         copyright notice that is included in or attached to the work
+         (an example is provided in the Appendix below).
+
+         "Derivative Works" shall mean any work, whether in Source or Object
+         form, that is based on (or derived from) the Work and for which the
+         editorial revisions, annotations, elaborations, or other modifications
+         represent, as a whole, an original work of authorship. For the purposes
+         of this License, Derivative Works shall not include works that remain
+         separable from, or merely link (or bind by name) to the interfaces of,
+         the Work and Derivative Works thereof.
+
+         "Contribution" shall mean any work of authorship, including
+         the original version of the Work and any modifications or additions
+         to that Work or Derivative Works thereof, that is intentionally
+         submitted to Licensor for inclusion in the Work by the copyright owner
+         or by an individual or Legal Entity authorized to submit on behalf of
+         the copyright owner. For the purposes of this definition, "submitted"
+         means any form of electronic, verbal, or written communication sent
+         to the Licensor or its representatives, including but not limited to
+         communication on electronic mailing lists, source code control systems,
+         and issue tracking systems that are managed by, or on behalf of, the
+         Licensor for the purpose of discussing and improving the Work, but
+         excluding communication that is conspicuously marked or otherwise
+         designated in writing by the copyright owner as "Not a Contribution."
+
+         "Contributor" shall mean Licensor and any individual or Legal Entity
+         on behalf of whom a Contribution has been received by Licensor and
+         subsequently incorporated within the Work.
+
+      2. Grant of Copyright License. Subject to the terms and conditions of
+         this License, each Contributor hereby grants to You a perpetual,
+         worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+         copyright license to reproduce, prepare Derivative Works of,
+         publicly display, publicly perform, sublicense, and distribute the
+         Work and such Derivative Works in Source or Object form.
+
+      3. Grant of Patent License. Subject to the terms and conditions of
+         this License, each Contributor hereby grants to You a perpetual,
+         worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+         (except as stated in this section) patent license to make, have made,
+         use, offer to sell, sell, import, and otherwise transfer the Work,
+         where such license applies only to those patent claims licensable
+         by such Contributor that are necessarily infringed by their
+         Contribution(s) alone or by combination of their Contribution(s)
+         with the Work to which such Contribution(s) was submitted. If You
+         institute patent litigation against any entity (including a
+         cross-claim or counterclaim in a lawsuit) alleging that the Work
+         or a Contribution incorporated within the Work constitutes direct
+         or contributory patent infringement, then any patent licenses
+         granted to You under this License for that Work shall terminate
+         as of the date such litigation is filed.
+
+      4. Redistribution. You may reproduce and distribute copies of the
+         Work or Derivative Works thereof in any medium, with or without
+         modifications, and in Source or Object form, provided that You
+         meet the following conditions:
+
+         a.  You must give any other recipients of the Work or
+             Derivative Works a copy of this License; and
+
+         b.  You must cause any modified files to carry prominent notices
+             stating that You changed the files; and
+
+         c.  You must retain, in the Source form of any Derivative Works
+             that You distribute, all copyright, patent, trademark, and
+             attribution notices from the Source form of the Work,
+             excluding those notices that do not pertain to any part of
+             the Derivative Works; and
+
+         d.  If the Work includes a "NOTICE" text file as part of its
+             distribution, then any Derivative Works that You distribute must
+             include a readable copy of the attribution notices contained
+             within such NOTICE file, excluding those notices that do not
+             pertain to any part of the Derivative Works, in at least one
+             of the following places: within a NOTICE text file distributed
+             as part of the Derivative Works; within the Source form or
+             documentation, if provided along with the Derivative Works; or,
+             within a display generated by the Derivative Works, if and
+             wherever such third-party notices normally appear. The contents
+             of the NOTICE file are for informational purposes only and
+             do not modify the License. You may add Your own attribution
+             notices within Derivative Works that You distribute, alongside
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+             that such additional attribution notices cannot be construed
+             as modifying the License.
+
+         You may add Your own copyright statement to Your modifications and
+         may provide additional or different license terms and conditions
+         for use, reproduction, or distribution of Your modifications, or
+         for any such Derivative Works as a whole, provided Your use,
+         reproduction, and distribution of the Work otherwise complies with
+         the conditions stated in this License.
+
+      5. Submission of Contributions. Unless You explicitly state otherwise,
+         any Contribution intentionally submitted for inclusion in the Work
+         by You to the Licensor shall be under the terms and conditions of
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+         Notwithstanding the above, nothing herein shall supersede or modify
+         the terms of any separate license agreement you may have executed
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+         whether in tort (including negligence), contract, or otherwise,
+         unless required by applicable law (such as deliberate and grossly
+         negligent acts) or agreed to in writing, shall any Contributor be
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+         Work (including but not limited to damages for loss of goodwill,
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+         or other liability obligations and/or rights consistent with this
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+         on Your own behalf and on Your sole responsibility, not on behalf
+         of any other Contributor, and only if You agree to indemnify,
+         defend, and hold each Contributor harmless for any liability
+         incurred by, or claims asserted against, such Contributor by reason
+         of your accepting any such warranty or additional liability.
+
+      END OF TERMS AND CONDITIONS
+
+      APPENDIX: How to apply the Apache License to your work.
+
+      >>>
+         To apply the Apache License to your work, attach the following
+         boilerplate notice, with the fields enclosed by brackets "[]"
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+
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diff --git a/NEWS.md b/NEWS.md
index df9d7e42b0..2b021e7cdd 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,302 +1,87 @@
-# NEWS for Ruby 3.2.0
+# NEWS for Ruby 4.1.0
 
 This document is a list of user-visible feature changes
-since the **3.1.0** release, except for bug fixes.
+since the **4.0.0** release, except for bug fixes.
 
 Note that each entry is kept to a minimum, see links for details.
 
 ## Language changes
 
-* Anonymous rest and keyword rest arguments can now be passed as
-  arguments, instead of just used in method parameters.
-  [[Feature #18351]]
-
-    ```ruby
-    def foo(*)
-      bar(*)
-    end
-    def baz(**)
-      quux(**)
-    end
-    ```
-
-* A proc that accepts a single positional argument and keywords will
-  no longer autosplat. [[Bug #18633]]
-
-  ```ruby
-  proc{|a, **k| a}.call([1, 2])
-  # Ruby 3.1 and before
-  # => 1
-  # Ruby 3.2 and after
-  # => [1, 2]
-  ```
-
-* Constant assignment evaluation order for constants set on explicit
-  objects has been made consistent with single attribute assignment
-  evaluation order. With this code:
-
-    ```ruby
-    foo::BAR = baz
-    ```
-
-  `foo` is now called before `baz`. Similarly, for multiple assignments
-  to constants,  left-to-right evaluation order is used. With this
-  code:
-
-    ```ruby
-      foo1::BAR1, foo2::BAR2 = baz1, baz2
-    ```
-
-  The following evaluation order is now used:
-
-  1. `foo1`
-  2. `foo2`
-  3. `baz1`
-  4. `baz2`
-
-  [[Bug #15928]]
-
-* Find pattern is no longer experimental.
-  [[Feature #18585]]
-
-* Methods taking a rest parameter (like `*args`) and wishing to delegate keyword
-  arguments through `foo(*args)` must now be marked with `ruby2_keywords`
-  (if not already the case). In other words, all methods wishing to delegate
-  keyword arguments through `*args` must now be marked with `ruby2_keywords`,
-  with no exception. This will make it easier to transition to other ways of
-  delegation once a library can require Ruby 3+. Previously, the `ruby2_keywords`
-  flag was kept if the receiving method took `*args`, but this was a bug and an
-  inconsistency. A good technique to find the potentially-missing `ruby2_keywords`
-  is to run the test suite, for where it fails find the last method which must
-  receive keyword arguments, use `puts nil, caller, nil` there, and check each
-  method/block on the call chain which must delegate keywords is correctly marked
-  as `ruby2_keywords`. [[Bug #18625]] [[Bug #16466]]
-
-    ```ruby
-    def target(**kw)
-    end
-
-    # Accidentally worked without ruby2_keywords in Ruby 2.7-3.1, ruby2_keywords
-    # needed in 3.2+. Just like (*args, **kwargs) or (...) would be needed on
-    # both #foo and #bar when migrating away from ruby2_keywords.
-    ruby2_keywords def bar(*args)
-      target(*args)
-    end
-
-    ruby2_keywords def foo(*args)
-      bar(*args)
-    end
-
-    foo(k: 1)
-    ```
-
-## Command line options
-
 ## Core classes updates
 
 Note: We're only listing outstanding class updates.
 
-* Encoding
-    * Encoding#replicate has been deprecated and will be removed in 3.3. [[Feature #18949]]
-    * The dummy `Encoding::UTF_16` and `Encoding::UTF_32` encodings no longer
-      try to dynamically guess the endian based on a byte order mark.
-      Use `Encoding::UTF_16BE/UTF_16LE` and `Encoding::UTF_32BE/UTF_32LE` instead.
-      This change speeds up getting the encoding of a String. [[Feature #18949]]
+* Method
 
-* Enumerator
-    * Enumerator.product has been added.  Enumerator::Product is the implementation. [[Feature #18685]]
+    * `Method#source_location`, `Proc#source_location`, and
+      `UnboundMethod#source_location` now return extended location
+      information with 5 elements: `[path, start_line, start_column,
+      end_line, end_column]`. The previous 2-element format `[path,
+      line]` can still be obtained by calling `.take(2)` on the result.
+      [[Feature #6012]]
 
-* Hash
-    * Hash#shift now always returns nil if the hash is
-      empty, instead of returning the default value or
-      calling the default proc. [[Bug #16908]]
+* Set
 
-* Integer
-    * Integer#ceildiv has been added. [[Feature #18809]]
+    * A deprecated behavior, `Set#to_set`, `Range#to_set`, and
+      `Enumerable#to_set` accepting arguments, was removed.  [[Feature #21390]]
 
-* Kernel
-    * Kernel#binding raises RuntimeError if called from a non-Ruby frame
-      (such as a method defined in C). [[Bug #18487]]
+## Stdlib updates
 
-* MatchData
-    * MatchData#byteoffset has been added. [[Feature #13110]]
+### The following bundled gems are added.
 
-* Module
-    * Module.used_refinements has been added. [[Feature #14332]]
-    * Module#refinements has been added. [[Feature #12737]]
-    * Module#const_added has been added. [[Feature #17881]]
-    * Module#undefined_instance_methods has been added. [[Feature #12655]]
 
-* Proc
-    * Proc#dup returns an instance of subclass. [[Bug #17545]]
-    * Proc#parameters now accepts lambda keyword. [[Feature #15357]]
+We only list stdlib changes that are notable feature changes.
 
-* Regexp
-    * Regexp.new now supports passing the regexp flags not only as an Integer,
-      but also as a String Unknown flags raise errors.  Otherwise, anything
-      other than `true`, `false`, `nil` or Integer will be warned.
-      [[Feature #18788]]
+Other changes are listed in the following sections. We also listed release
+history from the previous bundled version that is Ruby 3.4.0 if it has GitHub
+releases.
 
-* Refinement
-    * Refinement#refined_class has been added. [[Feature #12737]]
+### The following bundled gem is promoted from default gems.
 
-* Set
-    * Set is now available as a built-in class without the need for `require "set"`. [[Feature #16989]]
-      It is currently autoloaded via the `Set` constant or a call to `Enumerable#to_set`.
-
-* String
-    * String#byteindex and String#byterindex have been added. [[Feature #13110]]
-    * Update Unicode to Version 14.0.0 and Emoji Version 14.0. [[Feature #18037]]
-      (also applies to Regexp)
-    * String#bytesplice has been added.  [[Feature #18598]]
-
-* Struct
-    * A Struct class can also be initialized with keyword arguments
-      without `keyword_init: true` on `Struct.new` [[Feature #16806]]
-
-* TracePoint
-    * TracePoint#binding now returns `nil` for `c_call`/`c_return` TracePoints.
-      [[Bug #18487]]
-    * TracePoint#enable `target_thread` keyword argument now defaults to the
-      current thread if `target` and `target_line` keyword arguments are not
-      passed. [[Bug #16889]]
+* tsort 0.2.0
 
-## Stdlib updates
-
-* SyntaxSuggest
-
-  * The feature of `syntax_suggest` formerly `dead_end` is integrated in Ruby.
-    [[Feature #18159]]
-
-*   The following default gems are updated.
-    * RubyGems 3.4.0.dev
-    * bigdecimal 3.1.2
-    * bundler 2.4.0.dev
-    * cgi 0.3.2
-    * date 3.2.3
-    * error_highlight 0.4.0
-    * etc 1.4.0
-    * io-console 0.5.11
-    * io-nonblock 0.1.1
-    * io-wait 0.3.0.pre
-    * ipaddr 1.2.4
-    * json 2.6.2
-    * logger 1.5.1
-    * net-http 0.2.2
-    * net-protocol 0.1.3
-    * ostruct 0.5.5
-    * psych 5.0.0.dev
-    * reline 0.3.1
-    * securerandom 0.2.0
-    * set 1.0.3
-    * stringio 3.0.3
-    * syntax_suggest 0.0.1
-    * timeout 0.3.0
-*   The following bundled gems are updated.
-    * minitest 5.16.3
-    * net-imap 0.2.3
-    * rbs 2.6.0
-    * typeprof 0.21.3
-    * debug 1.6.2
-*   The following default gems are now bundled gems.
+### The following default gem is added.
 
-## Compatibility issues
+### The following default gems are updated.
 
-Note: Excluding feature bug fixes.
+* RubyGems 4.1.0.dev
+* bundler 4.1.0.dev
+* prism 1.8.0
+* stringio 3.2.1.dev
+* strscan 3.1.7.dev
 
-### Removed constants
+### The following bundled gems are updated.
 
-The following deprecated constants are removed.
+* minitest 6.0.1
+* test-unit 3.7.7
+* rss 0.3.2
+* net-imap 0.6.2
+* rbs 3.10.2
+* typeprof 0.31.1
+* debug 1.11.1
+* mutex_m 0.3.0
+* resolv-replace 0.2.0
+* rdoc 7.1.0
 
-* `Fixnum` and `Bignum` [[Feature #12005]]
-* `Random::DEFAULT` [[Feature #17351]]
-* `Struct::Group`
-* `Struct::Passwd`
+### RubyGems and Bundler
 
-### Removed methods
+Ruby 4.0 bundled RubyGems and Bundler version 4. see the following links for details.
 
-The following deprecated methods are removed.
+## Supported platforms
 
-* `Dir.exists?` [[Feature #17391]]
-* `File.exists?` [[Feature #17391]]
-* `Kernel#=~` [[Feature #15231]]
-* `Kernel#taint`, `Kernel#untaint`, `Kernel#tainted?`
-  [[Feature #16131]]
-* `Kernel#trust`, `Kernel#untrust`, `Kernel#untrusted?`
-  [[Feature #16131]]
+## Compatibility issues
 
 ## Stdlib compatibility issues
 
-* `Psych` no longer bundles libyaml sources.
-  Users need to install the libyaml library themselves via the package
-  system. [[Feature #18571]]
-
 ## C API updates
 
-### Removed C APIs
-
-The following deprecated APIs are removed.
-
-* `rb_cData` variable.
-* "taintedness" and "trustedness" functions. [[Feature #16131]]
-
 ## Implementation improvements
 
-* Fixed several race conditions in `Kernel#autoload`. [[Bug #18782]]
+### Ractor
+
+A lot of work has gone into making Ractors more stable, performant, and usable. These improvements bring Ractor implementation closer to leaving experimental status.
 
 ## JIT
 
-### YJIT
-
-* Support arm64 / aarch64 on UNIX platforms.
-* Building YJIT requires Rust 1.58.1+. [[Feature #18481]]
-
-### MJIT
-
-## Static analysis
-
-### RBS
-
-### TypeProf
-
-## Debugger
-
-## error_highlight
-
-## IRB Autocomplete and Document Display
-
-## Miscellaneous changes
-
-[Feature #12005]: https://bugs.ruby-lang.org/issues/12005
-[Feature #12655]: https://bugs.ruby-lang.org/issues/12655
-[Feature #12737]: https://bugs.ruby-lang.org/issues/12737
-[Feature #13110]: https://bugs.ruby-lang.org/issues/13110
-[Feature #14332]: https://bugs.ruby-lang.org/issues/14332
-[Feature #15231]: https://bugs.ruby-lang.org/issues/15231
-[Feature #15357]: https://bugs.ruby-lang.org/issues/15357
-[Bug #15928]:     https://bugs.ruby-lang.org/issues/15928
-[Feature #16131]: https://bugs.ruby-lang.org/issues/16131
-[Bug #16466]:     https://bugs.ruby-lang.org/issues/16466
-[Feature #16806]: https://bugs.ruby-lang.org/issues/16806
-[Bug #16889]:     https://bugs.ruby-lang.org/issues/16889
-[Bug #16908]:     https://bugs.ruby-lang.org/issues/16908
-[Feature #16989]: https://bugs.ruby-lang.org/issues/16989
-[Feature #17351]: https://bugs.ruby-lang.org/issues/17351
-[Feature #17391]: https://bugs.ruby-lang.org/issues/17391
-[Bug #17545]:     https://bugs.ruby-lang.org/issues/17545
-[Feature #17881]: https://bugs.ruby-lang.org/issues/17881
-[Feature #18037]: https://bugs.ruby-lang.org/issues/18037
-[Feature #18159]: https://bugs.ruby-lang.org/issues/18159
-[Feature #18351]: https://bugs.ruby-lang.org/issues/18351
-[Bug #18487]:     https://bugs.ruby-lang.org/issues/18487
-[Feature #18571]: https://bugs.ruby-lang.org/issues/18571
-[Feature #18585]: https://bugs.ruby-lang.org/issues/18585
-[Feature #18598]: https://bugs.ruby-lang.org/issues/18598
-[Bug #18625]:     https://bugs.ruby-lang.org/issues/18625
-[Bug #18633]:     https://bugs.ruby-lang.org/issues/18633
-[Feature #18685]: https://bugs.ruby-lang.org/issues/18685
-[Bug #18782]:     https://bugs.ruby-lang.org/issues/18782
-[Feature #18788]: https://bugs.ruby-lang.org/issues/18788
-[Feature #18809]: https://bugs.ruby-lang.org/issues/18809
-[Feature #18481]: https://bugs.ruby-lang.org/issues/18481
-[Feature #18949]: https://bugs.ruby-lang.org/issues/18949
+[Feature #6012]: https://bugs.ruby-lang.org/issues/6012
+[Feature #21390]: https://bugs.ruby-lang.org/issues/21390
diff --git a/README.ja.md b/README.ja.md
index bb69c09055..9bbc3a83a5 100644
--- a/README.ja.md
+++ b/README.ja.md
@@ -1,10 +1,10 @@
 [![Actions Status: MinGW](https://github.com/ruby/ruby/workflows/MinGW/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"MinGW")
-[![Actions Status: MJIT](https://github.com/ruby/ruby/workflows/MJIT/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"MJIT")
 [![Actions Status: Ubuntu](https://github.com/ruby/ruby/workflows/Ubuntu/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Ubuntu")
 [![Actions Status: Windows](https://github.com/ruby/ruby/workflows/Windows/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Windows")
 [![AppVeyor status](https://ci.appveyor.com/api/projects/status/0sy8rrxut4o0k960/branch/master?svg=true)](https://ci.appveyor.com/project/ruby/ruby/branch/master)
 [![Travis Status](https://app.travis-ci.com/ruby/ruby.svg?branch=master)](https://app.travis-ci.com/ruby/ruby)
-[![Cirrus Status](https://api.cirrus-ci.com/github/ruby/ruby.svg)](https://cirrus-ci.com/github/ruby/ruby/master)
+
+[English](rdoc-ref:README.md)
 
 # Rubyとは
 
@@ -26,7 +26,7 @@ Rubyはテキスト処理関係の能力などに優れ，Perlと同じくらい
 *   ダイナミックローディング (アーキテクチャによる)
 *   移植性が高い．多くのUnix-like/POSIX互換プラットフォーム上で動くだけでなく，Windows， macOS，
     Haikuなどの上でも動く cf.
-    https://github.com/ruby/ruby/blob/master/doc/contributing.rdoc#platform-maintainers
+    https://docs.ruby-lang.org/en/master/maintainers_md.html#label-Platform+Maintainers
 
 
 ## 入手法
@@ -41,26 +41,19 @@ https://www.ruby-lang.org/ja/downloads/
 
 ミラーをGitHubに公開しています． 以下のコマンドでリポジトリを取得できます．
 
-    $ git clone https://github.com/ruby/ruby.git
+```console
+$ git clone https://github.com/ruby/ruby.git
+```
 
 他のブランチの一覧は次のコマンドで見られます．
 
-    $ git ls-remote https://github.com/ruby/ruby.git
+```console
+$ git ls-remote https://github.com/ruby/ruby.git
+```
 
 Rubyリポジトリの本来のmasterは https://git.ruby-lang.org/ruby.git にあります．
 コミッタはこちらを使います．
 
-### Subversion
-
-古いRubyのバージョンのソースコードは次のコマンドでも取得できます．
-
-    $ svn co https://svn.ruby-lang.org/repos/ruby/branches/ruby_2_6/ ruby
-
-他のブランチの一覧は次のコマンドで見られます．
-
-    $ svn ls https://svn.ruby-lang.org/repos/ruby/branches/
-
-
 ## ホームページ
 
 RubyのホームページのURLは
@@ -71,20 +64,20 @@ https://www.ruby-lang.org/
 
 ## メーリングリスト
 
-Rubyのメーリングリストがあります．参加希望の方は [ruby-list-request@ruby-lang.org] まで本文に
+Rubyのメーリングリストがあります．参加希望の方は [ruby-list-request@ml.ruby-lang.org] まで件名に
 
-    subscribe
+    join
 
 と書いて送って下さい．
 
 Ruby開発者向けメーリングリストもあります．こちらではrubyのバグ，将来の仕様拡張など実装上の問題について議論されています．
-参加希望の方は [ruby-dev-request@ruby-lang.org] までruby-listと同様の方法でメールしてください．
+参加希望の方は [ruby-dev-request@ml.ruby-lang.org] までruby-listと同様の方法でメールしてください．
 
 Ruby拡張モジュールについて話し合うruby-extメーリングリストと数学関係の話題について話し合うruby-mathメーリングリストと
 英語でrubyについて話し合うruby-talkメーリングリストもあります．参加方法はどれも同じです．
 
-[ruby-list-request@ruby-lang.org]: mailto:ruby-list-request@ruby-lang.org?subject=Join%20Ruby%20Mailing%20List&body=subscribe
-[ruby-dev-request@ruby-lang.org]: mailto:ruby-dev-request@ruby-lang.org?subject=Join%20Ruby%20Mailing%20List&body=subscribe
+[ruby-list-request@ml.ruby-lang.org]: mailto:ruby-list-request@ml.ruby-lang.org?subject=join
+[ruby-dev-request@ml.ruby-lang.org]: mailto:ruby-dev-request@ml.ruby-lang.org?subject=join
 
 ## コンパイル・インストール
 
@@ -163,7 +156,7 @@ UNIXであれば `configure` がほとんどの差異を吸収してくれるは
 
 ## 配布条件
 
-[COPYING.ja](COPYING.ja) ファイルを参照してください．
+[COPYING.ja](https://docs.ruby-lang.org/en/master/COPYING_ja.html) ファイルを参照してください．
 
 ## フィードバック
 
diff --git a/README.md b/README.md
index 35ef2d9e89..02435b419e 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,9 @@
 [![Actions Status: MinGW](https://github.com/ruby/ruby/workflows/MinGW/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"MinGW")
-[![Actions Status: MJIT](https://github.com/ruby/ruby/workflows/MJIT/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"MJIT")
 [![Actions Status: Ubuntu](https://github.com/ruby/ruby/workflows/Ubuntu/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Ubuntu")
 [![Actions Status: Windows](https://github.com/ruby/ruby/workflows/Windows/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Windows")
-[![AppVeyor status](https://ci.appveyor.com/api/projects/status/0sy8rrxut4o0k960/branch/master?svg=true)](https://ci.appveyor.com/project/ruby/ruby/branch/master)
 [![Travis Status](https://app.travis-ci.com/ruby/ruby.svg?branch=master)](https://app.travis-ci.com/ruby/ruby)
-[![Cirrus Status](https://api.cirrus-ci.com/github/ruby/ruby.svg)](https://cirrus-ci.com/github/ruby/ruby/master)
+
+[日本語](rdoc-ref:README.ja.md)
 
 # What is Ruby?
 
@@ -25,15 +24,20 @@ It is simple, straightforward, and extensible.
 * Dynamic Loading of Object Files (on some architectures)
 * Highly Portable (works on many Unix-like/POSIX compatible platforms as
   well as Windows, macOS, etc.) cf.
-  https://github.com/ruby/ruby/blob/master/doc/maintainers.rdoc#label-Platform+Maintainers
+    https://docs.ruby-lang.org/en/master/maintainers_md.html#label-Platform+Maintainers
 
-## How to get Ruby with Git
+## How to get Ruby
 
 For a complete list of ways to install Ruby, including using third-party tools
 like rvm, see:
 
 https://www.ruby-lang.org/en/downloads/
 
+You can download release packages and the snapshot of the repository. If you want to
+download whole versions of Ruby, please visit https://www.ruby-lang.org/en/downloads/releases/.
+
+### Download with Git
+
 The mirror of the Ruby source tree can be checked out with the following command:
 
     $ git clone https://github.com/ruby/ruby.git
@@ -48,7 +52,7 @@ if you are a committer.
 
 ## How to build
 
-see [Building Ruby](doc/contributing/building_ruby.md)
+See [Building Ruby](https://docs.ruby-lang.org/en/master/contributing/building_ruby_md.html)
 
 ## Ruby home page
 
@@ -64,11 +68,11 @@ https://www.ruby-lang.org/
 There is a mailing list to discuss Ruby. To subscribe to this list, please
 send the following phrase:
 
-    subscribe
+    join
 
-in the mail body (not subject) to the address [ruby-talk-request@ruby-lang.org].
+in the mail subject (not body) to the address [ruby-talk-request@ml.ruby-lang.org].
 
-[ruby-talk-request@ruby-lang.org]: mailto:ruby-talk-request@ruby-lang.org?subject=Join%20Ruby%20Mailing%20List&body=subscribe
+[ruby-talk-request@ml.ruby-lang.org]: mailto:ruby-talk-request@ml.ruby-lang.org?subject=join
 
 ## Copying
 
@@ -83,7 +87,7 @@ Bugs should be reported at https://bugs.ruby-lang.org. Read ["Reporting Issues"]
 
 ## Contributing
 
-See ["Contributing to Ruby"](https://docs.ruby-lang.org/en/master/contributing_md.html), which includes setup and build instructions.
+See ["Contributing to Ruby"](https://docs.ruby-lang.org/en/master/contributing/contributing_md.html), which includes setup and build instructions.
 
 ## The Author
 
diff --git a/addr2line.c b/addr2line.c
index fe4ad84423..19a6a425c1 100644
--- a/addr2line.c
+++ b/addr2line.c
@@ -8,10 +8,14 @@
 
 **********************************************************************/
 
-#if defined(__clang__)
+#if defined(__clang__) && defined(__has_warning)
+#if __has_warning("-Wgnu-empty-initializer")
 #pragma clang diagnostic ignored "-Wgnu-empty-initializer"
+#endif
+#if __has_warning("-Wgcc-compat")
 #pragma clang diagnostic ignored "-Wgcc-compat"
 #endif
+#endif
 
 #include "ruby/internal/config.h"
 #include "ruby/defines.h"
@@ -52,13 +56,26 @@
 #  ifdef _AIX
 #pragma alloca
 #  else
-#   ifndef alloca		/* predefined by HP cc +Olibcalls */
+#   ifndef alloca                /* predefined by HP cc +Olibcalls */
 void *alloca();
 #   endif
 #  endif /* AIX */
-# endif	/* HAVE_ALLOCA_H */
+# endif        /* HAVE_ALLOCA_H */
+# ifndef UNREACHABLE
+#  define UNREACHABLE __builtin_unreachable()
+# endif
+# ifndef UNREACHABLE_RETURN
+#  define UNREACHABLE_RETURN(_) __builtin_unreachable()
+# endif
 #endif /* __GNUC__ */
 
+#ifndef UNREACHABLE
+# define UNREACHABLE abort()
+#endif
+#ifndef UNREACHABLE_RETURN
+# define UNREACHABLE_RETURN(_) return (abort(), (_))
+#endif
+
 #ifdef HAVE_DLADDR
 # include <dlfcn.h>
 #endif
@@ -127,7 +144,7 @@ void *alloca();
 #define DW_LNE_define_file              0x03
 #define DW_LNE_set_discriminator        0x04  /* DWARF4 */
 
-PRINTF_ARGS(static int kprintf(const char *fmt, ...), 1, 2);
+#define kprintf(...) fprintf(errout, "" __VA_ARGS__)
 
 typedef struct line_info {
     const char *dirname;
@@ -159,12 +176,15 @@ typedef struct obj_info {
     struct dwarf_section debug_info;
     struct dwarf_section debug_line;
     struct dwarf_section debug_ranges;
+    struct dwarf_section debug_str_offsets;
+    struct dwarf_section debug_addr;
     struct dwarf_section debug_rnglists;
     struct dwarf_section debug_str;
+    struct dwarf_section debug_line_str;
     struct obj_info *next;
 } obj_info_t;
 
-#define DWARF_SECTION_COUNT 6
+#define DWARF_SECTION_COUNT 9
 
 static struct dwarf_section *
 obj_dwarf_section_at(obj_info_t *obj, int n)
@@ -174,11 +194,14 @@ obj_dwarf_section_at(obj_info_t *obj, int n)
         &obj->debug_info,
         &obj->debug_line,
         &obj->debug_ranges,
+        &obj->debug_str_offsets,
+        &obj->debug_addr,
         &obj->debug_rnglists,
-        &obj->debug_str
+        &obj->debug_str,
+        &obj->debug_line_str
     };
     if (n < 0 || DWARF_SECTION_COUNT <= n) {
-        abort();
+        UNREACHABLE_RETURN(0);
     }
     return ary[n];
 }
@@ -197,13 +220,13 @@ uleb128(const char **p)
     unsigned long r = 0;
     int s = 0;
     for (;;) {
-	unsigned char b = (unsigned char)*(*p)++;
-	if (b < 0x80) {
-	    r += (unsigned long)b << s;
-	    break;
-	}
-	r += (b & 0x7f) << s;
-	s += 7;
+        unsigned char b = (unsigned char)*(*p)++;
+        if (b < 0x80) {
+            r += (unsigned long)b << s;
+            break;
+        }
+        r += (b & 0x7f) << s;
+        s += 7;
     }
     return r;
 }
@@ -214,85 +237,103 @@ sleb128(const char **p)
     long r = 0;
     int s = 0;
     for (;;) {
-	unsigned char b = (unsigned char)*(*p)++;
-	if (b < 0x80) {
-	    if (b & 0x40) {
-		r -= (0x80 - b) << s;
-	    }
-	    else {
-		r += (b & 0x3f) << s;
-	    }
-	    break;
-	}
-	r += (b & 0x7f) << s;
-	s += 7;
+        unsigned char b = (unsigned char)*(*p)++;
+        if (b < 0x80) {
+            if (b & 0x40) {
+                r -= (0x80 - b) << s;
+            }
+            else {
+                r += (b & 0x3f) << s;
+            }
+            break;
+        }
+        r += (b & 0x7f) << s;
+        s += 7;
     }
     return r;
 }
 
 static const char *
-get_nth_dirname(unsigned long dir, const char *p)
+get_nth_dirname(unsigned long dir, const char *p, FILE *errout)
 {
     if (!dir--) {
-	return "";
+        return "";
     }
     while (dir--) {
-	while (*p) p++;
-	p++;
-	if (!*p) {
-	    kprintf("Unexpected directory number %lu in %s\n",
-		    dir, binary_filename);
-	    return "";
-	}
+        while (*p) p++;
+        p++;
+        if (!*p) {
+            kprintf("Unexpected directory number %lu in %s\n",
+                    dir, binary_filename);
+            return "";
+        }
     }
     return p;
 }
 
+static const char *parse_ver5_debug_line_header(
+    const char *p, int idx, uint8_t format,
+    obj_info_t *obj, const char **out_path,
+    uint64_t *out_directory_index, FILE *errout);
+
 static void
-fill_filename(int file, const char *include_directories, const char *filenames, line_info_t *line, obj_info_t *obj)
+fill_filename(int file, uint8_t format, uint16_t version, const char *include_directories,
+              const char *filenames, line_info_t *line, obj_info_t *obj, FILE *errout)
 {
     int i;
     const char *p = filenames;
     const char *filename;
     unsigned long dir;
-    for (i = 1; i <= file; i++) {
-	filename = p;
-	if (!*p) {
-	    /* Need to output binary file name? */
-	    kprintf("Unexpected file number %d in %s at %tx\n",
-		    file, binary_filename, filenames - obj->mapped);
-	    return;
-	}
-	while (*p) p++;
-	p++;
-	dir = uleb128(&p);
-	/* last modified. */
-	uleb128(&p);
-	/* size of the file. */
-	uleb128(&p);
-
-	if (i == file) {
-	    line->filename = filename;
-	    line->dirname = get_nth_dirname(dir, include_directories);
-	}
+    if (version >= 5) {
+        const char *path;
+        uint64_t directory_index = -1;
+        parse_ver5_debug_line_header(filenames, file, format, obj, &path, &directory_index, errout);
+        line->filename = path;
+        parse_ver5_debug_line_header(include_directories, (int)directory_index, format, obj, &path, NULL, errout);
+        line->dirname = path;
+    }
+    else {
+        for (i = 1; i <= file; i++) {
+            filename = p;
+            if (!*p) {
+#ifndef __APPLE__
+                /* Need to output binary file name? */
+                kprintf("Unexpected file number %d in %s at %tx\n",
+                        file, binary_filename, filenames - obj->mapped);
+#endif
+                return;
+            }
+            while (*p) p++;
+            p++;
+            dir = uleb128(&p);
+            /* last modified. */
+            uleb128(&p);
+            /* size of the file. */
+            uleb128(&p);
+
+            if (i == file) {
+                line->filename = filename;
+                line->dirname = get_nth_dirname(dir, include_directories, errout);
+            }
+        }
     }
 }
 
 static void
 fill_line(int num_traces, void **traces, uintptr_t addr, int file, int line,
-	  const char *include_directories, const char *filenames,
-	  obj_info_t *obj, line_info_t *lines, int offset)
+          uint8_t format, uint16_t version, const char *include_directories, const char *filenames,
+          obj_info_t *obj, line_info_t *lines, int offset, FILE *errout)
 {
     int i;
     addr += obj->base_addr - obj->vmaddr;
     for (i = offset; i < num_traces; i++) {
-	uintptr_t a = (uintptr_t)traces[i];
-	/* We assume one line code doesn't result >100 bytes of native code.
+        uintptr_t a = (uintptr_t)traces[i];
+        /* We assume one line code doesn't result >100 bytes of native code.
        We may want more reliable way eventually... */
-	if (addr < a && a < addr + 100) {
-	    fill_filename(file, include_directories, filenames, &lines[i], obj);
-	    lines[i].line = line;
-	}
+        if (addr < a && a < addr + 100) {
+            fill_filename(file, format, version, include_directories, filenames, &lines[i], obj, errout);
+            lines[i].line = line;
+        }
     }
 }
 
@@ -315,7 +356,7 @@ struct LineNumberProgramHeader {
 };
 
 static int
-parse_debug_line_header(const char **pp, struct LineNumberProgramHeader *header)
+parse_debug_line_header(obj_info_t *obj, const char **pp, struct LineNumberProgramHeader *header, FILE *errout)
 {
     const char *p = *pp;
     header->unit_length = *(uint32_t *)p;
@@ -323,8 +364,8 @@ parse_debug_line_header(const char **pp, struct LineNumberProgramHeader *header)
 
     header->format = 4;
     if (header->unit_length == 0xffffffff) {
-	header->unit_length = *(uint64_t *)p;
-	p += sizeof(uint64_t);
+        header->unit_length = *(uint64_t *)p;
+        p += sizeof(uint64_t);
         header->format = 8;
     }
 
@@ -332,7 +373,13 @@ parse_debug_line_header(const char **pp, struct LineNumberProgramHeader *header)
 
     header->version = *(uint16_t *)p;
     p += sizeof(uint16_t);
-    if (header->version > 4) return -1;
+    if (header->version > 5) return -1;
+
+    if (header->version >= 5) {
+        /* address_size = *(uint8_t *)p++; */
+        /* segment_selector_size = *(uint8_t *)p++; */
+        p += 2;
+    }
 
     header->header_length = header->format == 4 ? *(uint32_t *)p : *(uint64_t *)p;
     p += header->format;
@@ -353,20 +400,27 @@ parse_debug_line_header(const char **pp, struct LineNumberProgramHeader *header)
     /* header->standard_opcode_lengths = (uint8_t *)p - 1; */
     p += header->opcode_base - 1;
 
-    header->include_directories = p;
+    if (header->version >= 5) {
+        header->include_directories = p;
+        p = parse_ver5_debug_line_header(p, -1, header->format, obj, NULL, NULL, errout);
+        header->filenames = p;
+    }
+    else {
+        header->include_directories = p;
 
-    /* temporary measure for compress-debug-sections */
-    if (p >= header->cu_end) return -1;
+        /* temporary measure for compress-debug-sections */
+        if (p >= header->cu_end) return -1;
 
-    /* skip include directories */
-    while (*p) {
-	p = memchr(p, '\0', header->cu_end - p);
-	if (!p) return -1;
-	p++;
-    }
-    p++;
+        /* skip include directories */
+        while (*p) {
+            p = memchr(p, '\0', header->cu_end - p);
+            if (!p) return -1;
+            p++;
+        }
+        p++;
 
-    header->filenames = p;
+        header->filenames = p;
+    }
 
     *pp = header->cu_start;
 
@@ -375,7 +429,7 @@ parse_debug_line_header(const char **pp, struct LineNumberProgramHeader *header)
 
 static int
 parse_debug_line_cu(int num_traces, void **traces, const char **debug_line,
-		obj_info_t *obj, line_info_t *lines, int offset)
+                obj_info_t *obj, line_info_t *lines, int offset, FILE *errout)
 {
     const char *p = (const char *)*debug_line;
     struct LineNumberProgramHeader header;
@@ -392,107 +446,109 @@ parse_debug_line_cu(int num_traces, void **traces, const char **debug_line,
     /* int epilogue_begin = 0; */
     /* unsigned int isa = 0; */
 
-    if (parse_debug_line_header(&p, &header))
+    if (parse_debug_line_header(obj, &p, &header, errout))
         return -1;
     is_stmt = header.default_is_stmt;
 
-#define FILL_LINE()						    \
-    do {							    \
-	fill_line(num_traces, traces, addr, file, line,		    \
+#define FILL_LINE()                                                 \
+    do {                                                            \
+        fill_line(num_traces, traces, addr, file, line,             \
+                  header.format,                                    \
+                  header.version,                                   \
                   header.include_directories,                       \
                   header.filenames,                                 \
-		  obj, lines, offset);				    \
-	/*basic_block = prologue_end = epilogue_begin = 0;*/	    \
+                  obj, lines, offset, errout);                      \
+        /*basic_block = prologue_end = epilogue_begin = 0;*/        \
     } while (0)
 
     while (p < header.cu_end) {
-	unsigned long a;
-	unsigned char op = *p++;
-	switch (op) {
-	case DW_LNS_copy:
-	    FILL_LINE();
-	    break;
-	case DW_LNS_advance_pc:
-	    a = uleb128(&p) * header.minimum_instruction_length;
-	    addr += a;
-	    break;
-	case DW_LNS_advance_line: {
-	    long a = sleb128(&p);
-	    line += a;
-	    break;
-	}
-	case DW_LNS_set_file:
-	    file = (unsigned int)uleb128(&p);
-	    break;
-	case DW_LNS_set_column:
-	    /*column = (unsigned int)*/(void)uleb128(&p);
-	    break;
-	case DW_LNS_negate_stmt:
-	    is_stmt = !is_stmt;
-	    break;
-	case DW_LNS_set_basic_block:
-	    /*basic_block = 1; */
-	    break;
-	case DW_LNS_const_add_pc:
-	    a = ((255UL - header.opcode_base) / header.line_range) *
-		header.minimum_instruction_length;
-	    addr += a;
-	    break;
-	case DW_LNS_fixed_advance_pc:
-	    a = *(uint16_t *)p;
-	    p += sizeof(uint16_t);
-	    addr += a;
-	    break;
-	case DW_LNS_set_prologue_end:
-	    /* prologue_end = 1; */
-	    break;
-	case DW_LNS_set_epilogue_begin:
-	    /* epilogue_begin = 1; */
-	    break;
-	case DW_LNS_set_isa:
-	    /* isa = (unsigned int)*/(void)uleb128(&p);
-	    break;
-	case 0:
-	    a = uleb128(&p);
-	    op = *p++;
-	    switch (op) {
-	    case DW_LNE_end_sequence:
-		/* end_sequence = 1; */
-		FILL_LINE();
-		addr = 0;
-		file = 1;
-		line = 1;
-		/* column = 0; */
-		is_stmt = header.default_is_stmt;
-		/* end_sequence = 0; */
-		/* isa = 0; */
-		break;
-	    case DW_LNE_set_address:
-		addr = *(unsigned long *)p;
-		p += sizeof(unsigned long);
-		break;
-	    case DW_LNE_define_file:
-		kprintf("Unsupported operation in %s\n",
-			binary_filename);
-		break;
-	    case DW_LNE_set_discriminator:
-		/* TODO:currently ignore */
-		uleb128(&p);
-		break;
-	    default:
-		kprintf("Unknown extended opcode: %d in %s\n",
-			op, binary_filename);
-	    }
-	    break;
-	default: {
+        unsigned long a;
+        unsigned char op = *p++;
+        switch (op) {
+        case DW_LNS_copy:
+            FILL_LINE();
+            break;
+        case DW_LNS_advance_pc:
+            a = uleb128(&p) * header.minimum_instruction_length;
+            addr += a;
+            break;
+        case DW_LNS_advance_line: {
+            long a = sleb128(&p);
+            line += a;
+            break;
+        }
+        case DW_LNS_set_file:
+            file = (unsigned int)uleb128(&p);
+            break;
+        case DW_LNS_set_column:
+            /*column = (unsigned int)*/(void)uleb128(&p);
+            break;
+        case DW_LNS_negate_stmt:
+            is_stmt = !is_stmt;
+            break;
+        case DW_LNS_set_basic_block:
+            /*basic_block = 1; */
+            break;
+        case DW_LNS_const_add_pc:
+            a = ((255UL - header.opcode_base) / header.line_range) *
+                header.minimum_instruction_length;
+            addr += a;
+            break;
+        case DW_LNS_fixed_advance_pc:
+            a = *(uint16_t *)p;
+            p += sizeof(uint16_t);
+            addr += a;
+            break;
+        case DW_LNS_set_prologue_end:
+            /* prologue_end = 1; */
+            break;
+        case DW_LNS_set_epilogue_begin:
+            /* epilogue_begin = 1; */
+            break;
+        case DW_LNS_set_isa:
+            /* isa = (unsigned int)*/(void)uleb128(&p);
+            break;
+        case 0:
+            a = uleb128(&p);
+            op = *p++;
+            switch (op) {
+            case DW_LNE_end_sequence:
+                /* end_sequence = 1; */
+                FILL_LINE();
+                addr = 0;
+                file = 1;
+                line = 1;
+                /* column = 0; */
+                is_stmt = header.default_is_stmt;
+                /* end_sequence = 0; */
+                /* isa = 0; */
+                break;
+            case DW_LNE_set_address:
+                addr = *(unsigned long *)p;
+                p += sizeof(unsigned long);
+                break;
+            case DW_LNE_define_file:
+                kprintf("Unsupported operation in %s\n",
+                        binary_filename);
+                break;
+            case DW_LNE_set_discriminator:
+                /* TODO:currently ignore */
+                uleb128(&p);
+                break;
+            default:
+                kprintf("Unknown extended opcode: %d in %s\n",
+                        op, binary_filename);
+            }
+            break;
+        default: {
             uint8_t adjusted_opcode = op - header.opcode_base;
             uint8_t operation_advance = adjusted_opcode / header.line_range;
             /* NOTE: this code doesn't support VLIW */
             addr += operation_advance * header.minimum_instruction_length;
             line += header.line_base + (adjusted_opcode % header.line_range);
-	    FILL_LINE();
-	}
-	}
+            FILL_LINE();
+        }
+        }
     }
     *debug_line = (char *)p;
     return 0;
@@ -500,17 +556,17 @@ parse_debug_line_cu(int num_traces, void **traces, const char **debug_line,
 
 static int
 parse_debug_line(int num_traces, void **traces,
-		 const char *debug_line, unsigned long size,
-		 obj_info_t *obj, line_info_t *lines, int offset)
+                 const char *debug_line, unsigned long size,
+                 obj_info_t *obj, line_info_t *lines, int offset, FILE *errout)
 {
     const char *debug_line_end = debug_line + size;
     while (debug_line < debug_line_end) {
-	if (parse_debug_line_cu(num_traces, traces, &debug_line, obj, lines, offset))
-	    return -1;
+        if (parse_debug_line_cu(num_traces, traces, &debug_line, obj, lines, offset, errout))
+            return -1;
     }
     if (debug_line != debug_line_end) {
-	kprintf("Unexpected size of .debug_line in %s\n",
-		binary_filename);
+        kprintf("Unexpected size of .debug_line in %s\n",
+                binary_filename);
     }
     return 0;
 }
@@ -518,7 +574,7 @@ parse_debug_line(int num_traces, void **traces,
 /* read file and fill lines */
 static uintptr_t
 fill_lines(int num_traces, void **traces, int check_debuglink,
-	   obj_info_t **objp, line_info_t *lines, int offset);
+           obj_info_t **objp, line_info_t *lines, int offset, FILE *errout);
 
 static void
 append_obj(obj_info_t **objp)
@@ -546,7 +602,7 @@ append_obj(obj_info_t **objp)
 // check the path pattern of "/usr/lib/debug/usr/bin/ruby.debug"
 static void
 follow_debuglink(const char *debuglink, int num_traces, void **traces,
-		 obj_info_t **objp, line_info_t *lines, int offset)
+                 obj_info_t **objp, line_info_t *lines, int offset, FILE *errout)
 {
     static const char global_debug_dir[] = "/usr/lib/debug";
     const size_t global_debug_dir_len = sizeof(global_debug_dir) - 1;
@@ -556,13 +612,13 @@ follow_debuglink(const char *debuglink, int num_traces, void **traces,
 
     p = strrchr(binary_filename, '/');
     if (!p) {
-	return;
+        return;
     }
     p[1] = '\0';
 
     len = strlen(binary_filename);
     if (len >= PATH_MAX - global_debug_dir_len)
-	len = PATH_MAX - global_debug_dir_len - 1;
+        len = PATH_MAX - global_debug_dir_len - 1;
     memmove(binary_filename + global_debug_dir_len, binary_filename, len);
     memcpy(binary_filename, global_debug_dir, global_debug_dir_len);
     len += global_debug_dir_len;
@@ -572,21 +628,22 @@ follow_debuglink(const char *debuglink, int num_traces, void **traces,
     o2 = *objp;
     o2->base_addr = o1->base_addr;
     o2->path = o1->path;
-    fill_lines(num_traces, traces, 0, objp, lines, offset);
+    fill_lines(num_traces, traces, 0, objp, lines, offset, errout);
 }
 
 // check the path pattern of "/usr/lib/debug/.build-id/ab/cdef1234.debug"
 static void
 follow_debuglink_build_id(const char *build_id, size_t build_id_size, int num_traces, void **traces,
-                          obj_info_t **objp, line_info_t *lines, int offset)
+                          obj_info_t **objp, line_info_t *lines, int offset, FILE *errout)
 {
     static const char global_debug_dir[] = "/usr/lib/debug/.build-id/";
+    static const char debug_suffix[] = ".debug";
     const size_t global_debug_dir_len = sizeof(global_debug_dir) - 1;
     char *p;
     obj_info_t *o1 = *objp, *o2;
     size_t i;
 
-    if (PATH_MAX < global_debug_dir_len + 1 + build_id_size * 2 + 6) return;
+    if (PATH_MAX < global_debug_dir_len + build_id_size * 2 + sizeof(debug_suffix)) return;
 
     memcpy(binary_filename, global_debug_dir, global_debug_dir_len);
     p = binary_filename + global_debug_dir_len;
@@ -597,13 +654,13 @@ follow_debuglink_build_id(const char *build_id, size_t build_id_size, int num_tr
         *p++ = tbl[n % 16];
         if (i == 0) *p++ = '/';
     }
-    strcpy(p, ".debug");
+    memcpy(p, debug_suffix, sizeof(debug_suffix));
 
     append_obj(objp);
     o2 = *objp;
     o2->base_addr = o1->base_addr;
     o2->path = o1->path;
-    fill_lines(num_traces, traces, 0, objp, lines, offset);
+    fill_lines(num_traces, traces, 0, objp, lines, offset, errout);
 }
 #endif
 
@@ -807,7 +864,11 @@ enum
     DW_FORM_addrx1 = 0x29,
     DW_FORM_addrx2 = 0x2a,
     DW_FORM_addrx3 = 0x2b,
-    DW_FORM_addrx4 = 0x2c
+    DW_FORM_addrx4 = 0x2c,
+
+    /* GNU extensions for referring to .gnu_debugaltlink dwz-compressed info */
+    DW_FORM_GNU_ref_alt = 0x1f20,
+    DW_FORM_GNU_strp_alt = 0x1f21
 };
 
 /* Range list entry encodings */
@@ -827,16 +888,23 @@ enum {
     VAL_cstr = 1,
     VAL_data = 2,
     VAL_uint = 3,
-    VAL_int = 4
+    VAL_int = 4,
+    VAL_addr = 5
 };
 
 # define ABBREV_TABLE_SIZE 256
 typedef struct {
     obj_info_t *obj;
     const char *file;
+    uint8_t current_version;
     const char *current_cu;
     uint64_t current_low_pc;
+    uint64_t current_str_offsets_base;
+    uint64_t current_addr_base;
+    uint64_t current_rnglists_base;
     const char *debug_line_cu_end;
+    uint8_t debug_line_format;
+    uint16_t debug_line_version;
     const char *debug_line_files;
     const char *debug_line_directories;
     const char *p;
@@ -861,6 +929,7 @@ typedef struct {
         const char *ptr;
         uint64_t uint64;
         int64_t int64;
+        uint64_t addr_idx;
     } as;
     uint64_t off;
     uint64_t at;
@@ -869,8 +938,11 @@ typedef struct {
     int type;
 } DebugInfoValue;
 
-/* TODO: Big Endian */
+#if defined(WORDS_BIGENDIAN)
+#define MERGE_2INTS(a,b,sz) (((uint64_t)(a)<<sz)|(b))
+#else
 #define MERGE_2INTS(a,b,sz) (((uint64_t)(b)<<sz)|(a))
+#endif
 
 static uint16_t
 get_uint16(const uint8_t *p)
@@ -973,6 +1045,9 @@ debug_info_reader_init(DebugInfoReader *reader, obj_info_t *obj)
     reader->pend = obj->debug_info.ptr + obj->debug_info.size;
     reader->debug_line_cu_end = obj->debug_line.ptr;
     reader->current_low_pc = 0;
+    reader->current_str_offsets_base = 0;
+    reader->current_addr_base = 0;
+    reader->current_rnglists_base = 0;
 }
 
 static void
@@ -1011,16 +1086,18 @@ di_read_debug_abbrev_cu(DebugInfoReader *reader)
 }
 
 static int
-di_read_debug_line_cu(DebugInfoReader *reader)
+di_read_debug_line_cu(DebugInfoReader *reader, FILE *errout)
 {
     const char *p;
     struct LineNumberProgramHeader header;
 
     p = (const char *)reader->debug_line_cu_end;
-    if (parse_debug_line_header(&p, &header))
+    if (parse_debug_line_header(reader->obj, &p, &header, errout))
         return -1;
 
     reader->debug_line_cu_end = (char *)header.cu_end;
+    reader->debug_line_format = header.format;
+    reader->debug_line_version = header.version;
     reader->debug_line_directories = (char *)header.include_directories;
     reader->debug_line_files = (char *)header.filenames;
 
@@ -1028,6 +1105,13 @@ di_read_debug_line_cu(DebugInfoReader *reader)
 }
 
 static void
+set_addr_idx_value(DebugInfoValue *v, uint64_t n)
+{
+    v->as.addr_idx = n;
+    v->type = VAL_addr;
+}
+
+static void
 set_uint_value(DebugInfoValue *v, uint64_t n)
 {
     v->as.uint64 = n;
@@ -1074,19 +1158,46 @@ get_cstr_value(DebugInfoValue *v)
     }
 }
 
-static void
-debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoValue *v)
+static const char *
+resolve_strx(DebugInfoReader *reader, uint64_t idx)
+{
+    const char *p = reader->obj->debug_str_offsets.ptr + reader->current_str_offsets_base;
+    uint64_t off;
+    if (reader->format == 4) {
+        off = ((uint32_t *)p)[idx];
+    }
+    else {
+        off = ((uint64_t *)p)[idx];
+    }
+    return reader->obj->debug_str.ptr + off;
+}
+
+static bool
+debug_info_reader_read_addr_value_member(DebugInfoReader *reader, DebugInfoValue *v, int size)
+{
+    if (size == 4) {
+        set_uint_value(v, read_uint32(&reader->p));
+    } else if (size == 8) {
+        set_uint_value(v, read_uint64(&reader->p));
+    } else {
+        return false;
+    }
+    return true;
+}
+
+#define debug_info_reader_read_addr_value(reader, v, mem) \
+    if (!debug_info_reader_read_addr_value_member((reader), (v), (reader)->mem)) { \
+        kprintf("unknown " #mem ":%d", (reader)->mem); \
+        return false; \
+    }
+
+
+static bool
+debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoValue *v, FILE *errout)
 {
     switch (form) {
       case DW_FORM_addr:
-        if (reader->address_size == 4) {
-            set_uint_value(v, read_uint32(&reader->p));
-        } else if (reader->address_size == 8) {
-            set_uint_value(v, read_uint64(&reader->p));
-        } else {
-            fprintf(stderr,"unknown address_size:%d", reader->address_size);
-            abort();
-        }
+        debug_info_reader_read_addr_value(reader, v, address_size);
         break;
       case DW_FORM_block2:
         v->size = read_uint16(&reader->p);
@@ -1138,13 +1249,12 @@ debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoVa
         set_uint_value(v, read_uleb128(reader));
         break;
       case DW_FORM_ref_addr:
-        if (reader->format == 4) {
-            set_uint_value(v, read_uint32(&reader->p));
-        } else if (reader->format == 8) {
-            set_uint_value(v, read_uint64(&reader->p));
+        if (reader->current_version <= 2) {
+            // DWARF Version 2 specifies that references have
+            // the same size as an address on the target system
+            debug_info_reader_read_addr_value(reader, v, address_size);
         } else {
-            fprintf(stderr,"unknown format:%d", reader->format);
-            abort();
+            debug_info_reader_read_addr_value(reader, v, format);
         }
         break;
       case DW_FORM_ref1:
@@ -1186,11 +1296,10 @@ debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoVa
         set_uint_value(v, 1);
         break;
       case DW_FORM_strx:
-        set_uint_value(v, uleb128(&reader->p));
+        set_cstr_value(v, resolve_strx(reader, uleb128(&reader->p)));
         break;
       case DW_FORM_addrx:
-        /* TODO: read .debug_addr */
-        set_uint_value(v, uleb128(&reader->p));
+        set_addr_idx_value(v, uleb128(&reader->p));
         break;
       case DW_FORM_ref_sup4:
         set_uint_value(v, read_uint32(&reader->p));
@@ -1205,8 +1314,7 @@ debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoVa
         reader->p += v->size;
         break;
       case DW_FORM_line_strp:
-        set_uint_value(v, read_uint(reader));
-        /* *p = reader->file + reader->line->sh_offset + ret; */
+        set_cstrp_value(v, reader->obj->debug_line_str.ptr, read_uint(reader));
         break;
       case DW_FORM_ref_sig8:
         set_uint_value(v, read_uint64(&reader->p));
@@ -1224,43 +1332,51 @@ debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoVa
         set_uint_value(v, read_uint64(&reader->p));
         break;
       case DW_FORM_strx1:
-        set_uint_value(v, read_uint8(&reader->p));
+        set_cstr_value(v, resolve_strx(reader, read_uint8(&reader->p)));
         break;
       case DW_FORM_strx2:
-        set_uint_value(v, read_uint16(&reader->p));
+        set_cstr_value(v, resolve_strx(reader, read_uint16(&reader->p)));
         break;
       case DW_FORM_strx3:
-        set_uint_value(v, read_uint24(&reader->p));
+        set_cstr_value(v, resolve_strx(reader, read_uint24(&reader->p)));
         break;
       case DW_FORM_strx4:
-        set_uint_value(v, read_uint32(&reader->p));
+        set_cstr_value(v, resolve_strx(reader, read_uint32(&reader->p)));
         break;
       case DW_FORM_addrx1:
-        set_uint_value(v, read_uint8(&reader->p));
+        set_addr_idx_value(v, read_uint8(&reader->p));
         break;
       case DW_FORM_addrx2:
-        set_uint_value(v, read_uint16(&reader->p));
+        set_addr_idx_value(v, read_uint16(&reader->p));
         break;
       case DW_FORM_addrx3:
-        set_uint_value(v, read_uint24(&reader->p));
+        set_addr_idx_value(v, read_uint24(&reader->p));
         break;
       case DW_FORM_addrx4:
-        set_uint_value(v, read_uint32(&reader->p));
+        set_addr_idx_value(v, read_uint32(&reader->p));
+        break;
+      /* we have no support for actually reading the real values of these refs out
+       * of the .gnu_debugaltlink dwz-compressed debuginfo at the moment, but "read"
+       * them anyway so that we advance the reader by the right amount. */
+      case DW_FORM_GNU_ref_alt:
+      case DW_FORM_GNU_strp_alt:
+        read_uint(reader);
+        set_uint_value(v, 0);
         break;
       case 0:
         goto fail;
         break;
     }
-    return;
+    return true;
 
   fail:
-    fprintf(stderr, "%d: unsupported form: %#"PRIx64"\n", __LINE__, form);
-    exit(1);
+    kprintf("%d: unsupported form: %#"PRIx64"\n", __LINE__, form);
+    return false;
 }
 
 /* find abbrev in current compilation unit */
 static const char *
-di_find_abbrev(DebugInfoReader *reader, uint64_t abbrev_number)
+di_find_abbrev(DebugInfoReader *reader, uint64_t abbrev_number, FILE *errout)
 {
     const char *p;
     if (abbrev_number < ABBREV_TABLE_SIZE) {
@@ -1273,8 +1389,8 @@ di_find_abbrev(DebugInfoReader *reader, uint64_t abbrev_number)
     di_skip_die_attributes(&p);
     for (uint64_t n = uleb128(&p); abbrev_number != n; n = uleb128(&p)) {
         if (n == 0) {
-            fprintf(stderr,"%d: Abbrev Number %"PRId64" not found\n",__LINE__, abbrev_number);
-            exit(1);
+            kprintf("%d: Abbrev Number %"PRId64" not found\n",__LINE__, abbrev_number);
+            return NULL;
         }
         uleb128(&p); /* tag */
         p++; /* has_children */
@@ -1285,52 +1401,52 @@ di_find_abbrev(DebugInfoReader *reader, uint64_t abbrev_number)
 
 #if 0
 static void
-hexdump0(const unsigned char *p, size_t n)
+hexdump0(const unsigned char *p, size_t n, FILE *errout)
 {
     size_t i;
-    fprintf(stderr, "     0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F\n");
+    kprintf("     0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F\n");
     for (i=0; i < n; i++){
         switch (i & 15) {
           case 0:
-            fprintf(stderr, "%02" PRIdSIZE ": %02X ", i/16, p[i]);
+            kprintf("%02" PRIdSIZE ": %02X ", i/16, p[i]);
             break;
           case 15:
-            fprintf(stderr, "%02X\n", p[i]);
+            kprintf("%02X\n", p[i]);
             break;
           default:
-            fprintf(stderr, "%02X ", p[i]);
+            kprintf("%02X ", p[i]);
             break;
         }
     }
     if ((i & 15) != 15) {
-        fprintf(stderr, "\n");
+        kprintf("\n");
     }
 }
-#define hexdump(p,n) hexdump0((const unsigned char *)p, n)
+#define hexdump(p,n,e) hexdump0((const unsigned char *)p, n, e)
 
 static void
-div_inspect(DebugInfoValue *v)
+div_inspect(DebugInfoValue *v, FILE *errout)
 {
     switch (v->type) {
       case VAL_uint:
-        fprintf(stderr,"%d: type:%d size:%" PRIxSIZE " v:%"PRIx64"\n",__LINE__,v->type,v->size,v->as.uint64);
+        kprintf("%d: type:%d size:%" PRIxSIZE " v:%"PRIx64"\n",__LINE__,v->type,v->size,v->as.uint64);
         break;
       case VAL_int:
-        fprintf(stderr,"%d: type:%d size:%" PRIxSIZE " v:%"PRId64"\n",__LINE__,v->type,v->size,(int64_t)v->as.uint64);
+        kprintf("%d: type:%d size:%" PRIxSIZE " v:%"PRId64"\n",__LINE__,v->type,v->size,(int64_t)v->as.uint64);
         break;
       case VAL_cstr:
-        fprintf(stderr,"%d: type:%d size:%" PRIxSIZE " v:'%s'\n",__LINE__,v->type,v->size,v->as.ptr);
+        kprintf("%d: type:%d size:%" PRIxSIZE " v:'%s'\n",__LINE__,v->type,v->size,v->as.ptr);
         break;
       case VAL_data:
-        fprintf(stderr,"%d: type:%d size:%" PRIxSIZE " v:\n",__LINE__,v->type,v->size);
-        hexdump(v->as.ptr, 16);
+        kprintf("%d: type:%d size:%" PRIxSIZE " v:\n",__LINE__,v->type,v->size);
+        hexdump(v->as.ptr, 16, errout);
         break;
     }
 }
 #endif
 
 static DIE *
-di_read_die(DebugInfoReader *reader, DIE *die)
+di_read_die(DebugInfoReader *reader, DIE *die, FILE *errout)
 {
     uint64_t abbrev_number = uleb128(&reader->p);
     if (abbrev_number == 0) {
@@ -1338,7 +1454,7 @@ di_read_die(DebugInfoReader *reader, DIE *die)
         return NULL;
     }
 
-    reader->q = di_find_abbrev(reader, abbrev_number);
+    if (!(reader->q = di_find_abbrev(reader, abbrev_number, errout))) return NULL;
 
     die->pos = reader->p - reader->obj->debug_info.ptr - 1;
     die->tag = (int)uleb128(&reader->q); /* tag */
@@ -1350,27 +1466,109 @@ di_read_die(DebugInfoReader *reader, DIE *die)
 }
 
 static DebugInfoValue *
-di_read_record(DebugInfoReader *reader, DebugInfoValue *vp)
+di_read_record(DebugInfoReader *reader, DebugInfoValue *vp, FILE *errout)
 {
     uint64_t at = uleb128(&reader->q);
     uint64_t form = uleb128(&reader->q);
     if (!at || !form) return NULL;
     vp->at = at;
     vp->form = form;
-    debug_info_reader_read_value(reader, form, vp);
+    if (!debug_info_reader_read_value(reader, form, vp, errout)) return NULL;
     return vp;
 }
 
-static void
-di_skip_records(DebugInfoReader *reader)
+static bool
+di_skip_records(DebugInfoReader *reader, FILE *errout)
 {
     for (;;) {
-        DebugInfoValue v = {{}};
+        DebugInfoValue v = {{0}};
         uint64_t at = uleb128(&reader->q);
         uint64_t form = uleb128(&reader->q);
-        if (!at || !form) return;
-        debug_info_reader_read_value(reader, form, &v);
+        if (!at || !form) return true;
+        if (!debug_info_reader_read_value(reader, form, &v, errout)) return false;
+    }
+}
+
+typedef struct addr_header {
+    const char *ptr;
+    uint64_t unit_length;
+    uint8_t format;
+    uint8_t address_size;
+    /* uint8_t segment_selector_size; */
+} addr_header_t;
+
+static bool
+addr_header_init(obj_info_t *obj, addr_header_t *header, FILE *errout)
+{
+    const char *p = obj->debug_addr.ptr;
+
+    header->ptr = p;
+
+    if (!p) return true;
+
+    header->unit_length = *(uint32_t *)p;
+    p += sizeof(uint32_t);
+
+    header->format = 4;
+    if (header->unit_length == 0xffffffff) {
+        header->unit_length = *(uint64_t *)p;
+        p += sizeof(uint64_t);
+        header->format = 8;
+    }
+
+    p += 2; /* version */
+    header->address_size = *p++;
+    if (header->address_size != 4 && header->address_size != 8) {
+        kprintf("unknown address_size:%d", header->address_size);
+        return false;
+    }
+    p++; /* segment_selector_size */
+    return true;
+}
+
+static uint64_t
+read_addr(addr_header_t *header, uint64_t addr_base, uint64_t idx) {
+    if (header->address_size == 4) {
+        return ((uint32_t*)(header->ptr + addr_base))[idx];
+    }
+    else {
+        return ((uint64_t*)(header->ptr + addr_base))[idx];
+    }
+}
+
+typedef struct rnglists_header {
+    uint64_t unit_length;
+    uint8_t format;
+    uint8_t address_size;
+    uint32_t offset_entry_count;
+} rnglists_header_t;
+
+static bool
+rnglists_header_init(obj_info_t *obj, rnglists_header_t *header, FILE *errout)
+{
+    const char *p = obj->debug_rnglists.ptr;
+
+    if (!p) return true;
+
+    header->unit_length = *(uint32_t *)p;
+    p += sizeof(uint32_t);
+
+    header->format = 4;
+    if (header->unit_length == 0xffffffff) {
+        header->unit_length = *(uint64_t *)p;
+        p += sizeof(uint64_t);
+        header->format = 8;
     }
+
+    p += 2; /* version */
+    header->address_size = *p++;
+    if (header->address_size != 4 && header->address_size != 8) {
+        kprintf("unknown address_size:%d", header->address_size);
+        return false;
+    }
+    p++; /* segment_selector_size */
+    header->offset_entry_count = *(uint32_t *)p;
+    return true;
 }
 
 typedef struct {
@@ -1383,50 +1581,54 @@ typedef struct {
 } ranges_t;
 
 static void
-ranges_set(ranges_t *ptr, DebugInfoValue *v)
+ranges_set(ranges_t *ptr, DebugInfoValue *v, addr_header_t *addr_header, uint64_t addr_base)
 {
+    uint64_t n = 0;
+    if (v->type == VAL_uint) {
+        n = v->as.uint64;
+    }
+    else if (v->type == VAL_addr) {
+        n = read_addr(addr_header, addr_base, v->as.addr_idx);
+    }
     switch (v->at) {
       case DW_AT_low_pc:
-        ptr->low_pc = v->as.uint64;
+        ptr->low_pc = n;
         ptr->low_pc_set = true;
         break;
       case DW_AT_high_pc:
         if (v->form == DW_FORM_addr) {
-            ptr->high_pc = v->as.uint64;
+            ptr->high_pc = n;
         }
         else {
-            ptr->high_pc = ptr->low_pc + v->as.uint64;
+            ptr->high_pc = ptr->low_pc + n;
         }
         ptr->high_pc_set = true;
         break;
       case DW_AT_ranges:
-        ptr->ranges = v->as.uint64;
+        ptr->ranges = n;
         ptr->ranges_set = true;
         break;
     }
 }
 
 static uint64_t
-read_dw_form_addr(DebugInfoReader *reader, const char **ptr)
+read_dw_form_addr(DebugInfoReader *reader, const char **ptr, FILE *errout)
 {
     const char *p = *ptr;
     *ptr = p + reader->address_size;
     if (reader->address_size == 4) {
         return read_uint32(&p);
-    } else if (reader->address_size == 8) {
-        return read_uint64(&p);
     } else {
-        fprintf(stderr,"unknown address_size:%d", reader->address_size);
-        abort();
+        return read_uint64(&p);
     }
 }
 
 static uintptr_t
-ranges_include(DebugInfoReader *reader, ranges_t *ptr, uint64_t addr)
+ranges_include(DebugInfoReader *reader, ranges_t *ptr, uint64_t addr, rnglists_header_t *rnglists_header, FILE *errout)
 {
     if (ptr->high_pc_set) {
         if (ptr->ranges_set || !ptr->low_pc_set) {
-            exit(1);
+            return UINTPTR_MAX;
         }
         if (ptr->low_pc <= addr && addr <= ptr->high_pc) {
             return (uintptr_t)ptr->low_pc;
@@ -1437,8 +1639,21 @@ ranges_include(DebugInfoReader *reader, ranges_t *ptr, uint64_t addr)
         const char *p;
         uint64_t base = ptr->low_pc_set ? ptr->low_pc : reader->current_low_pc;
         bool base_valid = true;
-        if (reader->obj->debug_rnglists.ptr) {
-            p = reader->obj->debug_rnglists.ptr + ptr->ranges;
+        if (reader->current_version >= 5) {
+            if (rnglists_header->offset_entry_count == 0) {
+                // DW_FORM_sec_offset
+                p = reader->obj->debug_rnglists.ptr + ptr->ranges + reader->current_rnglists_base;
+            }
+            else {
+                // DW_FORM_rnglistx
+                const char *offset_array = reader->obj->debug_rnglists.ptr + reader->current_rnglists_base;
+                if (rnglists_header->format == 4) {
+                    p = offset_array + ((uint32_t *)offset_array)[ptr->ranges];
+                }
+                else {
+                    p = offset_array + ((uint64_t *)offset_array)[ptr->ranges];
+                }
+            }
             for (;;) {
                 uint8_t rle = read_uint8(&p);
                 uintptr_t from = 0, to = 0;
@@ -1462,15 +1677,15 @@ ranges_include(DebugInfoReader *reader, ranges_t *ptr, uint64_t addr)
                     to = (uintptr_t)base + uleb128(&p);
                     break;
                   case DW_RLE_base_address:
-                    base = read_dw_form_addr(reader, &p);
+                    base = read_dw_form_addr(reader, &p, errout);
                     base_valid = true;
                     break;
                   case DW_RLE_start_end:
-                    from = (uintptr_t)read_dw_form_addr(reader, &p);
-                    to = (uintptr_t)read_dw_form_addr(reader, &p);
+                    from = (uintptr_t)read_dw_form_addr(reader, &p, errout);
+                    to = (uintptr_t)read_dw_form_addr(reader, &p, errout);
                     break;
                   case DW_RLE_start_length:
-                    from = (uintptr_t)read_dw_form_addr(reader, &p);
+                    from = (uintptr_t)read_dw_form_addr(reader, &p, errout);
                     to = from + uleb128(&p);
                     break;
                 }
@@ -1478,7 +1693,7 @@ ranges_include(DebugInfoReader *reader, ranges_t *ptr, uint64_t addr)
                     return from;
                 }
             }
-            return false;
+            return 0;
         }
         p = reader->obj->debug_ranges.ptr + ptr->ranges;
         for (;;) {
@@ -1499,42 +1714,42 @@ ranges_include(DebugInfoReader *reader, ranges_t *ptr, uint64_t addr)
             return (uintptr_t)ptr->low_pc;
         }
     }
-    return false;
+    return 0;
 }
 
 #if 0
 static void
-ranges_inspect(DebugInfoReader *reader, ranges_t *ptr)
+ranges_inspect(DebugInfoReader *reader, ranges_t *ptr, FILE *errout)
 {
     if (ptr->high_pc_set) {
         if (ptr->ranges_set || !ptr->low_pc_set) {
-            fprintf(stderr,"low_pc_set:%d high_pc_set:%d ranges_set:%d\n",ptr->low_pc_set,ptr->high_pc_set,ptr->ranges_set);
-            exit(1);
+            kprintf("low_pc_set:%d high_pc_set:%d ranges_set:%d\n",ptr->low_pc_set,ptr->high_pc_set,ptr->ranges_set);
+            return;
         }
-        fprintf(stderr,"low_pc:%"PRIx64" high_pc:%"PRIx64"\n",ptr->low_pc,ptr->high_pc);
+        kprintf("low_pc:%"PRIx64" high_pc:%"PRIx64"\n",ptr->low_pc,ptr->high_pc);
     }
     else if (ptr->ranges_set) {
         char *p = reader->obj->debug_ranges.ptr + ptr->ranges;
-        fprintf(stderr,"low_pc:%"PRIx64" ranges:%"PRIx64" %lx ",ptr->low_pc,ptr->ranges, p-reader->obj->mapped);
+        kprintf("low_pc:%"PRIx64" ranges:%"PRIx64" %lx ",ptr->low_pc,ptr->ranges, p-reader->obj->mapped);
         for (;;) {
             uintptr_t from = read_uintptr(&p);
             uintptr_t to = read_uintptr(&p);
             if (!from && !to) break;
-            fprintf(stderr,"%"PRIx64"-%"PRIx64" ",ptr->low_pc+from,ptr->low_pc+to);
+            kprintf("%"PRIx64"-%"PRIx64" ",ptr->low_pc+from,ptr->low_pc+to);
         }
-        fprintf(stderr,"\n");
+        kprintf("\n");
     }
     else if (ptr->low_pc_set) {
-        fprintf(stderr,"low_pc:%"PRIx64"\n",ptr->low_pc);
+        kprintf("low_pc:%"PRIx64"\n",ptr->low_pc);
     }
     else {
-        fprintf(stderr,"empty\n");
+        kprintf("empty\n");
     }
 }
 #endif
 
 static int
-di_read_cu(DebugInfoReader *reader)
+di_read_cu(DebugInfoReader *reader, FILE *errout)
 {
     uint64_t unit_length;
     uint16_t version;
@@ -1548,6 +1763,7 @@ di_read_cu(DebugInfoReader *reader)
     }
     reader->cu_end = reader->p + unit_length;
     version = read_uint16(&reader->p);
+    reader->current_version = version;
     if (version > 5) {
         return -1;
     }
@@ -1560,43 +1776,72 @@ di_read_cu(DebugInfoReader *reader)
         debug_abbrev_offset = read_uint(reader);
         reader->address_size = read_uint8(&reader->p);
     }
+    if (reader->address_size != 4 && reader->address_size != 8) {
+        kprintf("unknown address_size:%d", reader->address_size);
+        return -1;
+    }
     reader->q0 = reader->obj->debug_abbrev.ptr + debug_abbrev_offset;
 
     reader->level = 0;
     di_read_debug_abbrev_cu(reader);
-    if (di_read_debug_line_cu(reader)) return -1;
+    if (di_read_debug_line_cu(reader, errout)) return -1;
 
-#if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER_BUILD_DATE)
-    /* Though DWARF specifies "the applicable base address defaults to the base
-       address of the compilation unit", but GCC seems to use zero as default */
-#else
     do {
         DIE die;
 
-        if (!di_read_die(reader, &die)) continue;
+        if (!di_read_die(reader, &die, errout)) continue;
 
         if (die.tag != DW_TAG_compile_unit) {
-            di_skip_records(reader);
+            if (!di_skip_records(reader, errout)) return -1;
             break;
         }
 
+        reader->current_str_offsets_base = 0;
+        reader->current_addr_base = 0;
+        reader->current_rnglists_base = 0;
+
+        DebugInfoValue low_pc = {{0}};
         /* enumerate abbrev */
         for (;;) {
-            DebugInfoValue v = {{}};
-            if (!di_read_record(reader, &v)) break;
+            DebugInfoValue v = {{0}};
+            if (!di_read_record(reader, &v, errout)) break;
             switch (v.at) {
               case DW_AT_low_pc:
-                reader->current_low_pc = v.as.uint64;
+                // clang may output DW_AT_addr_base after DW_AT_low_pc.
+                // We need to resolve the DW_FORM_addr* after DW_AT_addr_base is parsed.
+                low_pc = v;
+                break;
+              case DW_AT_str_offsets_base:
+                reader->current_str_offsets_base = v.as.uint64;
+                break;
+              case DW_AT_addr_base:
+                reader->current_addr_base = v.as.uint64;
+                break;
+              case DW_AT_rnglists_base:
+                reader->current_rnglists_base = v.as.uint64;
                 break;
             }
         }
+        // Resolve the DW_FORM_addr of DW_AT_low_pc
+        switch (low_pc.type) {
+            case VAL_uint:
+                reader->current_low_pc = low_pc.as.uint64;
+                break;
+            case VAL_addr:
+                {
+                    addr_header_t header = {0};
+                    if (!addr_header_init(reader->obj, &header, errout)) return -1;
+                    reader->current_low_pc = read_addr(&header, reader->current_addr_base, low_pc.as.addr_idx);
+                }
+                break;
+        }
     } while (0);
-#endif
+
     return 0;
 }
 
 static void
-read_abstract_origin(DebugInfoReader *reader, uint64_t form, uint64_t abstract_origin, line_info_t *line)
+read_abstract_origin(DebugInfoReader *reader, uint64_t form, uint64_t abstract_origin, line_info_t *line, FILE *errout)
 {
     const char *p = reader->p;
     const char *q = reader->q;
@@ -1621,12 +1866,12 @@ read_abstract_origin(DebugInfoReader *reader, uint64_t form, uint64_t abstract_o
       default:
         goto finish;
     }
-    if (!di_read_die(reader, &die)) goto finish;
+    if (!di_read_die(reader, &die, errout)) goto finish;
 
     /* enumerate abbrev */
     for (;;) {
-        DebugInfoValue v = {{}};
-        if (!di_read_record(reader, &v)) break;
+        DebugInfoValue v = {{0}};
+        if (!di_read_record(reader, &v, errout)) break;
         switch (v.at) {
           case DW_AT_name:
             line->sname = get_cstr_value(&v);
@@ -1640,36 +1885,44 @@ read_abstract_origin(DebugInfoReader *reader, uint64_t form, uint64_t abstract_o
     reader->level = level;
 }
 
-static void
+static bool
 debug_info_read(DebugInfoReader *reader, int num_traces, void **traces,
-         line_info_t *lines, int offset) {
+                line_info_t *lines, int offset, FILE *errout)
+{
+
+    addr_header_t addr_header = {0};
+    if (!addr_header_init(reader->obj, &addr_header, errout)) return false;
+
+    rnglists_header_t rnglists_header = {0};
+    if (!rnglists_header_init(reader->obj, &rnglists_header, errout)) return false;
+
     while (reader->p < reader->cu_end) {
         DIE die;
-        ranges_t ranges = {};
-        line_info_t line = {};
+        ranges_t ranges = {0};
+        line_info_t line = {0};
 
-        if (!di_read_die(reader, &die)) continue;
-        /* fprintf(stderr,"%d:%tx: <%d>\n",__LINE__,die.pos,reader->level,die.tag); */
+        if (!di_read_die(reader, &die, errout)) continue;
+        /* kprintf("%d:%tx: <%d>\n",__LINE__,die.pos,reader->level,die.tag); */
 
         if (die.tag != DW_TAG_subprogram && die.tag != DW_TAG_inlined_subroutine) {
           skip_die:
-            di_skip_records(reader);
+            if (!di_skip_records(reader, errout)) return false;
             continue;
         }
 
         /* enumerate abbrev */
         for (;;) {
-            DebugInfoValue v = {{}};
+            DebugInfoValue v = {{0}};
             /* ptrdiff_t pos = reader->p - reader->p0; */
-            if (!di_read_record(reader, &v)) break;
-            /* fprintf(stderr,"\n%d:%tx: AT:%lx FORM:%lx\n",__LINE__,pos,v.at,v.form); */
-            /* div_inspect(&v); */
+            if (!di_read_record(reader, &v, errout)) break;
+            /* kprintf("\n%d:%tx: AT:%lx FORM:%lx\n",__LINE__,pos,v.at,v.form); */
+            /* div_inspect(&v, errout); */
             switch (v.at) {
               case DW_AT_name:
                 line.sname = get_cstr_value(&v);
                 break;
               case DW_AT_call_file:
-                fill_filename((int)v.as.uint64, reader->debug_line_directories, reader->debug_line_files, &line, reader->obj);
+                fill_filename((int)v.as.uint64, reader->debug_line_format, reader->debug_line_version, reader->debug_line_directories, reader->debug_line_files, &line, reader->obj, errout);
                 break;
               case DW_AT_call_line:
                 line.line = (int)v.as.uint64;
@@ -1677,7 +1930,7 @@ debug_info_read(DebugInfoReader *reader, int num_traces, void **traces,
               case DW_AT_low_pc:
               case DW_AT_high_pc:
               case DW_AT_ranges:
-                ranges_set(&ranges, &v);
+                ranges_set(&ranges, &v, &addr_header, reader->current_addr_base);
                 break;
               case DW_AT_declaration:
                 goto skip_die;
@@ -1685,18 +1938,19 @@ debug_info_read(DebugInfoReader *reader, int num_traces, void **traces,
                 /* 1 or 3 */
                 break; /* goto skip_die; */
               case DW_AT_abstract_origin:
-                read_abstract_origin(reader, v.form, v.as.uint64, &line);
+                read_abstract_origin(reader, v.form, v.as.uint64, &line, errout);
                 break; /* goto skip_die; */
             }
         }
-        /* ranges_inspect(reader, &ranges); */
-        /* fprintf(stderr,"%d:%tx: %x ",__LINE__,diepos,die.tag); */
+        /* ranges_inspect(reader, &ranges, errout); */
+        /* kprintf("%d:%tx: %x ",__LINE__,diepos,die.tag); */
         for (int i=offset; i < num_traces; i++) {
             uintptr_t addr = (uintptr_t)traces[i];
             uintptr_t offset = addr - reader->obj->base_addr + reader->obj->vmaddr;
-            uintptr_t saddr = ranges_include(reader, &ranges, offset);
+            uintptr_t saddr = ranges_include(reader, &ranges, offset, &rnglists_header, errout);
+            if (saddr == UINTPTR_MAX) return false;
             if (saddr) {
-                /* fprintf(stderr, "%d:%tx: %d %lx->%lx %x %s: %s/%s %d %s %s %s\n",__LINE__,die.pos, i,addr,offset, die.tag,line.sname,line.dirname,line.filename,line.line,reader->obj->path,line.sname,lines[i].sname); */
+                /* kprintf("%d:%tx: %d %lx->%lx %x %s: %s/%s %d %s %s %s\n",__LINE__,die.pos, i,addr,offset, die.tag,line.sname,line.dirname,line.filename,line.line,reader->obj->path,line.sname,lines[i].sname); */
                 if (lines[i].sname) {
                     line_info_t *lp = malloc(sizeof(line_info_t));
                     memcpy(lp, &lines[i], sizeof(line_info_t));
@@ -1713,6 +1967,58 @@ debug_info_read(DebugInfoReader *reader, int num_traces, void **traces,
             }
         }
     }
+    return true;
+}
+
+// This function parses the following attributes of Line Number Program Header in DWARF 5:
+//
+// * directory_entry_format_count
+// * directory_entry_format
+// * directories_count
+// * directories
+//
+// or
+//
+// * file_name_entry_format_count
+// * file_name_entry_format
+// * file_names_count
+// * file_names
+//
+// It records DW_LNCT_path and DW_LNCT_directory_index at the index "idx".
+static const char *
+parse_ver5_debug_line_header(const char *p, int idx, uint8_t format,
+                             obj_info_t *obj, const char **out_path,
+                             uint64_t *out_directory_index, FILE *errout)
+{
+    int i, j;
+    int entry_format_count = *(uint8_t *)p++;
+    const char *entry_format = p;
+
+    /* skip the part of entry_format */
+    for (i = 0; i < entry_format_count * 2; i++) uleb128(&p);
+
+    int entry_count = (int)uleb128(&p);
+
+    DebugInfoReader reader = {0};
+    debug_info_reader_init(&reader, obj);
+    reader.format = format;
+    reader.p = p;
+    for (j = 0; j < entry_count; j++) {
+        const char *format = entry_format;
+        for (i = 0; i < entry_format_count; i++) {
+            DebugInfoValue v = {{0}};
+            unsigned long dw_lnct = uleb128(&format);
+            unsigned long dw_form = uleb128(&format);
+            if (!debug_info_reader_read_value(&reader, dw_form, &v, errout)) return 0;
+            if (dw_lnct == 1 /* DW_LNCT_path */ && v.type == VAL_cstr && out_path)
+                *out_path = v.as.ptr + v.off;
+            if (dw_lnct == 2 /* DW_LNCT_directory_index */ && v.type == VAL_uint && out_directory_index)
+                *out_directory_index = v.as.uint64;
+        }
+        if (j == idx) return 0;
+    }
+
+    return reader.p;
 }
 
 #ifdef USE_ELF
@@ -1726,14 +2032,14 @@ uncompress_debug_section(ElfW(Shdr) *shdr, char *file, char **ptr)
     int ret = 0;
 
     if (chdr->ch_type != ELFCOMPRESS_ZLIB) {
-	/* unsupported compression type */
-	return 0;
+        /* unsupported compression type */
+        return 0;
     }
 
     *ptr = malloc(destsize);
     if (!*ptr) return 0;
     ret = uncompress((Bytef *)*ptr, &destsize,
-	    (const Bytef*)chdr + sizeof(ElfW(Chdr)),
+            (const Bytef*)chdr + sizeof(ElfW(Chdr)),
             shdr->sh_size - sizeof(ElfW(Chdr)));
     if (ret != Z_OK) goto fail;
     return destsize;
@@ -1748,7 +2054,7 @@ fail:
 /* read file and fill lines */
 static uintptr_t
 fill_lines(int num_traces, void **traces, int check_debuglink,
-	   obj_info_t **objp, line_info_t *lines, int offset)
+           obj_info_t **objp, line_info_t *lines, int offset, FILE *errout)
 {
     int i, j;
     char *shstr;
@@ -1766,40 +2072,40 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
 
     fd = open(binary_filename, O_RDONLY);
     if (fd < 0) {
-	goto fail;
+        goto fail;
     }
     filesize = lseek(fd, 0, SEEK_END);
     if (filesize < 0) {
-	int e = errno;
-	close(fd);
-	kprintf("lseek: %s\n", strerror(e));
-	goto fail;
+        int e = errno;
+        close(fd);
+        kprintf("lseek: %s\n", strerror(e));
+        goto fail;
     }
 #if SIZEOF_OFF_T > SIZEOF_SIZE_T
     if (filesize > (off_t)SIZE_MAX) {
-	close(fd);
-	kprintf("Too large file %s\n", binary_filename);
-	goto fail;
+        close(fd);
+        kprintf("Too large file %s\n", binary_filename);
+        goto fail;
     }
 #endif
     lseek(fd, 0, SEEK_SET);
     /* async-signal unsafe */
     file = (char *)mmap(NULL, (size_t)filesize, PROT_READ, MAP_SHARED, fd, 0);
     if (file == MAP_FAILED) {
-	int e = errno;
-	close(fd);
-	kprintf("mmap: %s\n", strerror(e));
-	goto fail;
+        int e = errno;
+        close(fd);
+        kprintf("mmap: %s\n", strerror(e));
+        goto fail;
     }
     close(fd);
 
     ehdr = (ElfW(Ehdr) *)file;
     if (memcmp(ehdr->e_ident, "\177ELF", 4) != 0) {
-	/*
-	 * Huh? Maybe filename was overridden by setproctitle() and
-	 * it match non-elf file.
-	 */
-	goto fail;
+        /*
+         * Huh? Maybe filename was overridden by setproctitle() and
+         * it match non-elf file.
+         */
+        goto fail;
     }
     obj->mapped = file;
     obj->mapped_size = (size_t)filesize;
@@ -1811,40 +2117,43 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
 
     for (i = 0; i < ehdr->e_shnum; i++) {
         char *section_name = shstr + shdr[i].sh_name;
-	switch (shdr[i].sh_type) {
-	  case SHT_STRTAB:
-	    if (!strcmp(section_name, ".strtab")) {
-		strtab_shdr = shdr + i;
-	    }
-	    else if (!strcmp(section_name, ".dynstr")) {
-		dynstr_shdr = shdr + i;
-	    }
-	    break;
-	  case SHT_SYMTAB:
-	    /* if (!strcmp(section_name, ".symtab")) */
-	    symtab_shdr = shdr + i;
-	    break;
-	  case SHT_DYNSYM:
-	    /* if (!strcmp(section_name, ".dynsym")) */
-	    dynsym_shdr = shdr + i;
-	    break;
+        switch (shdr[i].sh_type) {
+          case SHT_STRTAB:
+            if (!strcmp(section_name, ".strtab")) {
+                strtab_shdr = shdr + i;
+            }
+            else if (!strcmp(section_name, ".dynstr")) {
+                dynstr_shdr = shdr + i;
+            }
+            break;
+          case SHT_SYMTAB:
+            /* if (!strcmp(section_name, ".symtab")) */
+            symtab_shdr = shdr + i;
+            break;
+          case SHT_DYNSYM:
+            /* if (!strcmp(section_name, ".dynsym")) */
+            dynsym_shdr = shdr + i;
+            break;
           case SHT_NOTE:
             if (!strcmp(section_name, ".note.gnu.build-id")) {
                 note_gnu_build_id = shdr + i;
             }
             break;
-	  case SHT_PROGBITS:
-	    if (!strcmp(section_name, ".gnu_debuglink")) {
-		gnu_debuglink_shdr = shdr + i;
-	    }
+          case SHT_PROGBITS:
+            if (!strcmp(section_name, ".gnu_debuglink")) {
+                gnu_debuglink_shdr = shdr + i;
+            }
             else {
                 const char *debug_section_names[] = {
                     ".debug_abbrev",
                     ".debug_info",
                     ".debug_line",
                     ".debug_ranges",
+                    ".debug_str_offsets",
+                    ".debug_addr",
                     ".debug_rnglists",
-                    ".debug_str"
+                    ".debug_str",
+                    ".debug_line_str"
                 };
 
                 for (j=0; j < DWARF_SECTION_COUNT; j++) {
@@ -1863,17 +2172,16 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
                     break;
                 }
             }
-	    break;
-	}
+            break;
+        }
     }
 
-    if (offset == -1) {
-	/* main executable */
-	offset = 0;
-	if (dynsym_shdr && dynstr_shdr) {
-	    char *strtab = file + dynstr_shdr->sh_offset;
-	    ElfW(Sym) *symtab = (ElfW(Sym) *)(file + dynsym_shdr->sh_offset);
-	    int symtab_count = (int)(dynsym_shdr->sh_size / sizeof(ElfW(Sym)));
+    if (offset == 0) {
+        /* main executable */
+        if (dynsym_shdr && dynstr_shdr) {
+            char *strtab = file + dynstr_shdr->sh_offset;
+            ElfW(Sym) *symtab = (ElfW(Sym) *)(file + dynsym_shdr->sh_offset);
+            int symtab_count = (int)(dynsym_shdr->sh_size / sizeof(ElfW(Sym)));
             void *handle = dlopen(NULL, RTLD_NOW|RTLD_LOCAL);
             if (handle) {
                 for (j = 0; j < symtab_count; j++) {
@@ -1890,14 +2198,14 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
                 }
                 dlclose(handle);
             }
-	    if (ehdr->e_type == ET_EXEC) {
-		obj->base_addr = 0;
-	    }
-	    else {
-		/* PIE (position-independent executable) */
-		obj->base_addr = dladdr_fbase;
-	    }
-	}
+            if (ehdr->e_type == ET_EXEC) {
+                obj->base_addr = 0;
+            }
+            else {
+                /* PIE (position-independent executable) */
+                obj->base_addr = dladdr_fbase;
+            }
+        }
     }
 
     if (obj->debug_info.ptr && obj->debug_abbrev.ptr) {
@@ -1905,9 +2213,10 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
         debug_info_reader_init(&reader, obj);
         i = 0;
         while (reader.p < reader.pend) {
-            /* fprintf(stderr, "%d:%tx: CU[%d]\n", __LINE__, reader.p - reader.obj->debug_info.ptr, i++); */
-            if (di_read_cu(&reader)) goto use_symtab;
-            debug_info_read(&reader, num_traces, traces, lines, offset);
+            /* kprintf("%d:%tx: CU[%d]\n", __LINE__, reader.p - reader.obj->debug_info.ptr, i++); */
+            if (di_read_cu(&reader, errout)) goto use_symtab;
+            if (!debug_info_read(&reader, num_traces, traces, lines, offset, errout))
+                goto use_symtab;
         }
     }
     else {
@@ -1942,27 +2251,27 @@ use_symtab:
     }
 
     if (!obj->debug_line.ptr) {
-	/* This file doesn't have .debug_line section,
-	   let's check .gnu_debuglink section instead. */
-	if (gnu_debuglink_shdr && check_debuglink) {
-	    follow_debuglink(file + gnu_debuglink_shdr->sh_offset,
-			     num_traces, traces,
-			     objp, lines, offset);
-	}
+        /* This file doesn't have .debug_line section,
+           let's check .gnu_debuglink section instead. */
+        if (gnu_debuglink_shdr && check_debuglink) {
+            follow_debuglink(file + gnu_debuglink_shdr->sh_offset,
+                             num_traces, traces,
+                             objp, lines, offset, errout);
+        }
         if (note_gnu_build_id && check_debuglink) {
             ElfW(Nhdr) *nhdr = (ElfW(Nhdr)*) (file + note_gnu_build_id->sh_offset);
             const char *build_id = (char *)(nhdr + 1) + nhdr->n_namesz;
             follow_debuglink_build_id(build_id, nhdr->n_descsz,
-			       num_traces, traces,
-			       objp, lines, offset);
+                               num_traces, traces,
+                               objp, lines, offset, errout);
         }
-	goto finish;
+        goto finish;
     }
 
     if (parse_debug_line(num_traces, traces,
             obj->debug_line.ptr,
             obj->debug_line.size,
-            obj, lines, offset) == -1)
+            obj, lines, offset, errout) == -1)
         goto fail;
 
 finish:
@@ -1974,7 +2283,7 @@ fail:
 /* read file and fill lines */
 static uintptr_t
 fill_lines(int num_traces, void **traces, int check_debuglink,
-        obj_info_t **objp, line_info_t *lines, int offset)
+        obj_info_t **objp, line_info_t *lines, int offset, FILE *errout)
 {
 # ifdef __LP64__
 #  define LP(x) x##_64
@@ -2053,13 +2362,13 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
         struct fat_header *fat = (struct fat_header *)file;
         char *q = file + sizeof(*fat);
         uint32_t nfat_arch = __builtin_bswap32(fat->nfat_arch);
-        /* fprintf(stderr,"%d: fat:%s %d\n",__LINE__, binary_filename,nfat_arch); */
+        /* kprintf("%d: fat:%s %d\n",__LINE__, binary_filename,nfat_arch); */
         for (uint32_t i = 0; i < nfat_arch; i++) {
             struct fat_arch *arch = (struct fat_arch *)q;
             cpu_type_t cputype = __builtin_bswap32(arch->cputype);
             cpu_subtype_t cpusubtype = __builtin_bswap32(arch->cpusubtype);
             uint32_t offset = __builtin_bswap32(arch->offset);
-            /* fprintf(stderr,"%d: fat %d %x/%x %x/%x\n",__LINE__, i, mhp->cputype,mhp->cpusubtype, cputype,cpusubtype); */
+            /* kprintf("%d: fat %d %x/%x %x/%x\n",__LINE__, i, mhp->cputype,mhp->cpusubtype, cputype,cpusubtype); */
             if (mhp->cputype == cputype &&
                     (cpu_subtype_t)(mhp->cpusubtype & ~CPU_SUBTYPE_MASK) == cpusubtype) {
                 p = file + offset;
@@ -2077,13 +2386,14 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
         goto fail;
     }
     else {
-        kprintf("'%s' is not a "
 # ifdef __LP64__
-                "64"
+#   define bitsize "64"
 # else
-                "32"
+#   define bitsize "32"
 # endif
+        kprintf("'%s' is not a " bitsize
                 "-bit Mach-O file!\n",binary_filename);
+# undef bitsize
         close(fd);
         goto fail;
     }
@@ -2100,8 +2410,11 @@ found_mach_header:
                     "__debug_info",
                     "__debug_line",
                     "__debug_ranges",
+                    "__debug_str_offsets",
+                    "__debug_addr",
                     "__debug_rnglists",
-                    "__debug_str"
+                    "__debug_str",
+                    "__debug_line_str",
                 };
                 struct LP(segment_command) *scmd = (struct LP(segment_command) *)lcmd;
                 if (strcmp(scmd->segname, "__TEXT") == 0) {
@@ -2115,7 +2428,17 @@ found_mach_header:
                         for (int j=0; j < DWARF_SECTION_COUNT; j++) {
                             struct dwarf_section *s = obj_dwarf_section_at(obj, j);
 
-                            if (strcmp(sect->sectname, debug_section_names[j]) != 0)
+                            if (strcmp(sect->sectname, debug_section_names[j]) != 0
+#ifdef __APPLE__
+                                    /* macOS clang 16 generates DWARF5, which have Mach-O
+                                     * section names that are limited to 16 characters,
+                                     * which causes sections with long names to be truncated
+                                     * and not match above.
+                                     * See: https://wiki.dwarfstd.org/Best_Practices.md#Mach-2d-O
+                                     */
+                                    && strncmp(sect->sectname, debug_section_names[j], 16) != 0
+#endif
+                                )
                                 continue;
 
                             s->ptr = file + sect->offset;
@@ -2172,15 +2495,16 @@ found_mach_header:
         DebugInfoReader reader;
         debug_info_reader_init(&reader, obj);
         while (reader.p < reader.pend) {
-            if (di_read_cu(&reader)) goto fail;
-            debug_info_read(&reader, num_traces, traces, lines, offset);
+            if (di_read_cu(&reader, errout)) goto fail;
+            if (!debug_info_read(&reader, num_traces, traces, lines, offset, errout))
+                goto fail;
         }
     }
 
     if (parse_debug_line(num_traces, traces,
             obj->debug_line.ptr,
             obj->debug_line.size,
-            obj, lines, offset) == -1)
+            obj, lines, offset, errout) == -1)
         goto fail;
 
     return dladdr_fbase;
@@ -2193,7 +2517,7 @@ fail:
 #if defined(__FreeBSD__) || defined(__DragonFly__)
 # include <sys/sysctl.h>
 #endif
-/* ssize_t main_exe_path(void)
+/* ssize_t main_exe_path(FILE *errout)
  *
  * store the path of the main executable to `binary_filename`,
  * and returns strlen(binary_filename).
@@ -2201,7 +2525,7 @@ fail:
  */
 #if defined(__linux__) || defined(__NetBSD__)
 static ssize_t
-main_exe_path(void)
+main_exe_path(FILE *errout)
 {
 # if defined(__linux__)
 #  define PROC_SELF_EXE "/proc/self/exe"
@@ -2215,21 +2539,21 @@ main_exe_path(void)
 }
 #elif defined(__FreeBSD__) || defined(__DragonFly__)
 static ssize_t
-main_exe_path(void)
+main_exe_path(FILE *errout)
 {
     int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
     size_t len = PATH_MAX;
     int err = sysctl(mib, 4, binary_filename, &len, NULL, 0);
     if (err) {
-	kprintf("Can't get the path of ruby");
-	return -1;
+        kprintf("Can't get the path of ruby");
+        return -1;
     }
     len--; /* sysctl sets strlen+1 */
     return len;
 }
 #elif defined(HAVE_LIBPROC_H)
 static ssize_t
-main_exe_path(void)
+main_exe_path(FILE *errout)
 {
     int len = proc_pidpath(getpid(), binary_filename, PATH_MAX);
     if (len == 0) return 0;
@@ -2241,7 +2565,7 @@ main_exe_path(void)
 #endif
 
 static void
-print_line0(line_info_t *line, void *address)
+print_line0(line_info_t *line, void *address, FILE *errout)
 {
     uintptr_t addr = (uintptr_t)address;
     uintptr_t d = addr - line->saddr;
@@ -2282,16 +2606,16 @@ print_line0(line_info_t *line, void *address)
 }
 
 static void
-print_line(line_info_t *line, void *address)
+print_line(line_info_t *line, void *address, FILE *errout)
 {
-    print_line0(line, address);
+    print_line0(line, address, errout);
     if (line->next) {
-        print_line(line->next, NULL);
+        print_line(line->next, NULL, errout);
     }
 }
 
 void
-rb_dump_backtrace_with_lines(int num_traces, void **traces)
+rb_dump_backtrace_with_lines(int num_traces, void **traces, FILE *errout)
 {
     int i;
     /* async-signal unsafe */
@@ -2299,83 +2623,84 @@ rb_dump_backtrace_with_lines(int num_traces, void **traces)
     obj_info_t *obj = NULL;
     /* 2 is NULL + main executable */
     void **dladdr_fbases = (void **)calloc(num_traces+2, sizeof(void *));
+
 #ifdef HAVE_MAIN_EXE_PATH
     char *main_path = NULL; /* used on printing backtrace */
     ssize_t len;
-    if ((len = main_exe_path()) > 0) {
-	main_path = (char *)alloca(len + 1);
-	if (main_path) {
-	    uintptr_t addr;
-	    memcpy(main_path, binary_filename, len+1);
-	    append_obj(&obj);
-	    obj->path = main_path;
-	    addr = fill_lines(num_traces, traces, 1, &obj, lines, -1);
-	    if (addr != (uintptr_t)-1) {
-		dladdr_fbases[0] = (void *)addr;
-	    }
-	}
+    if ((len = main_exe_path(errout)) > 0) {
+        main_path = (char *)alloca(len + 1);
+        if (main_path) {
+            uintptr_t addr;
+            memcpy(main_path, binary_filename, len+1);
+            append_obj(&obj);
+            obj->path = main_path;
+            addr = fill_lines(num_traces, traces, 1, &obj, lines, 0, errout);
+            if (addr != (uintptr_t)-1) {
+                dladdr_fbases[0] = (void *)addr;
+            }
+        }
     }
 #endif
 
     /* fill source lines by reading dwarf */
     for (i = 0; i < num_traces; i++) {
-	Dl_info info;
-	if (lines[i].line) continue;
-	if (dladdr(traces[i], &info)) {
-	    const char *path;
-	    void **p;
-
-	    /* skip symbols which is in already checked objects */
-	    /* if the binary is strip-ed, this may effect */
-	    for (p=dladdr_fbases; *p; p++) {
-		if (*p == info.dli_fbase) {
-		    if (info.dli_fname) lines[i].path = info.dli_fname;
-		    if (info.dli_sname) lines[i].sname = info.dli_sname;
-		    goto next_line;
-		}
-	    }
-	    *p = info.dli_fbase;
-
-	    append_obj(&obj);
-	    obj->base_addr = (uintptr_t)info.dli_fbase;
-	    path = info.dli_fname;
-	    obj->path = path;
-	    if (path) lines[i].path = path;
+        Dl_info info;
+        if (lines[i].line) continue;
+        if (dladdr(traces[i], &info)) {
+            const char *path;
+            void **p;
+
+            /* skip symbols which is in already checked objects */
+            /* if the binary is strip-ed, this may effect */
+            for (p=dladdr_fbases; *p; p++) {
+                if (*p == info.dli_fbase) {
+                    if (info.dli_fname) lines[i].path = info.dli_fname;
+                    if (info.dli_sname) lines[i].sname = info.dli_sname;
+                    goto next_line;
+                }
+            }
+            *p = info.dli_fbase;
+
+            append_obj(&obj);
+            obj->base_addr = (uintptr_t)info.dli_fbase;
+            path = info.dli_fname;
+            obj->path = path;
+            if (path) lines[i].path = path;
             if (info.dli_sname) {
                 lines[i].sname = info.dli_sname;
                 lines[i].saddr = (uintptr_t)info.dli_saddr;
             }
-	    strlcpy(binary_filename, path, PATH_MAX);
-	    if (fill_lines(num_traces, traces, 1, &obj, lines, i) == (uintptr_t)-1)
-		break;
-	}
+            strlcpy(binary_filename, path, PATH_MAX);
+            if (fill_lines(num_traces, traces, 1, &obj, lines, i, errout) == (uintptr_t)-1)
+                break;
+        }
 next_line:
-	continue;
+        continue;
     }
 
     /* output */
     for (i = 0; i < num_traces; i++) {
-        print_line(&lines[i], traces[i]);
+        print_line(&lines[i], traces[i], errout);
 
-	/* FreeBSD's backtrace may show _start and so on */
-	if (lines[i].sname && strcmp("main", lines[i].sname) == 0)
-	    break;
+        /* FreeBSD's backtrace may show _start and so on */
+        if (lines[i].sname && strcmp("main", lines[i].sname) == 0)
+            break;
     }
 
     /* free */
     while (obj) {
-	obj_info_t *o = obj;
+        obj_info_t *o = obj;
         for (i=0; i < DWARF_SECTION_COUNT; i++) {
             struct dwarf_section *s = obj_dwarf_section_at(obj, i);
             if (s->flags & SHF_COMPRESSED) {
                 free(s->ptr);
             }
         }
-	if (obj->mapped_size) {
-	    munmap(obj->mapped, obj->mapped_size);
-	}
-	obj = o->next;
-	free(o);
+        if (obj->mapped_size) {
+            munmap(obj->mapped, obj->mapped_size);
+        }
+        obj = o->next;
+        free(o);
     }
     for (i = 0; i < num_traces; i++) {
         line_info_t *line = lines[i].next;
@@ -2389,435 +2714,8 @@ next_line:
     free(dladdr_fbases);
 }
 
-/* From FreeBSD's lib/libstand/printf.c */
-/*-
- * Copyright (c) 1986, 1988, 1991, 1993
- *	The Regents of the University of California.  All rights reserved.
- * (c) UNIX System Laboratories, Inc.
- * All or some portions of this file are derived from material licensed
- * to the University of California by American Telephone and Telegraph
- * Co. or Unix System Laboratories, Inc. and are reproduced herein with
- * the permission of UNIX System Laboratories, Inc.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- *	@(#)subr_prf.c	8.3 (Berkeley) 1/21/94
- */
-
-#include <stdarg.h>
-#define MAXNBUF (sizeof(intmax_t) * CHAR_BIT + 1)
-static inline int toupper(int c) { return ('A' <= c && c <= 'Z') ? (c&0x5f) : c; }
-#define    hex2ascii(hex)  (hex2ascii_data[hex])
-static const char hex2ascii_data[] = "0123456789abcdefghijklmnopqrstuvwxyz";
-static inline int imax(int a, int b) { return (a > b ? a : b); }
-static int kvprintf(char const *fmt, void (*func)(int), void *arg, int radix, va_list ap);
-
-static void putce(int c)
-{
-    char s[1];
-    ssize_t ret;
-
-    s[0] = (char)c;
-    ret = write(2, s, 1);
-    (void)ret;
-}
-
-static int
-kprintf(const char *fmt, ...)
-{
-	va_list ap;
-	int retval;
-
-	va_start(ap, fmt);
-	retval = kvprintf(fmt, putce, NULL, 10, ap);
-	va_end(ap);
-	return retval;
-}
-
-/*
- * Put a NUL-terminated ASCII number (base <= 36) in a buffer in reverse
- * order; return an optional length and a pointer to the last character
- * written in the buffer (i.e., the first character of the string).
- * The buffer pointed to by `nbuf' must have length >= MAXNBUF.
- */
-static char *
-ksprintn(char *nbuf, uintmax_t num, int base, int *lenp, int upper)
-{
-	char *p, c;
-
-	p = nbuf;
-	*p = '\0';
-	do {
-		c = hex2ascii(num % base);
-		*++p = upper ? toupper(c) : c;
-	} while (num /= base);
-	if (lenp)
-		*lenp = (int)(p - nbuf);
-	return (p);
-}
+#undef kprintf
 
-/*
- * Scaled down version of printf(3).
- *
- * Two additional formats:
- *
- * The format %b is supported to decode error registers.
- * Its usage is:
- *
- *	printf("reg=%b\n", regval, "<base><arg>*");
- *
- * where <base> is the output base expressed as a control character, e.g.
- * \10 gives octal; \20 gives hex.  Each arg is a sequence of characters,
- * the first of which gives the bit number to be inspected (origin 1), and
- * the next characters (up to a control character, i.e. a character <= 32),
- * give the name of the register.  Thus:
- *
- *	kvprintf("reg=%b\n", 3, "\10\2BITTWO\1BITONE\n");
- *
- * would produce output:
- *
- *	reg=3<BITTWO,BITONE>
- *
- * XXX:  %D  -- Hexdump, takes pointer and separator string:
- *		("%6D", ptr, ":")   -> XX:XX:XX:XX:XX:XX
- *		("%*D", len, ptr, " " -> XX XX XX XX ...
- */
-static int
-kvprintf(char const *fmt, void (*func)(int), void *arg, int radix, va_list ap)
-{
-#define PCHAR(c) {int cc=(c); if (func) (*func)(cc); else *d++ = cc; retval++; }
-	char nbuf[MAXNBUF];
-	char *d;
-	const char *p, *percent, *q;
-	unsigned char *up;
-	int ch, n;
-	uintmax_t num;
-	int base, lflag, qflag, tmp, width, ladjust, sharpflag, neg, sign, dot;
-	int cflag, hflag, jflag, tflag, zflag;
-	int dwidth, upper;
-	char padc;
-	int stop = 0, retval = 0;
-
-	num = 0;
-	if (!func)
-		d = (char *) arg;
-	else
-		d = NULL;
-
-	if (fmt == NULL)
-		fmt = "(fmt null)\n";
-
-	if (radix < 2 || radix > 36)
-		radix = 10;
-
-	for (;;) {
-		padc = ' ';
-		width = 0;
-		while ((ch = (unsigned char)*fmt++) != '%' || stop) {
-			if (ch == '\0')
-				return (retval);
-			PCHAR(ch);
-		}
-		percent = fmt - 1;
-		qflag = 0; lflag = 0; ladjust = 0; sharpflag = 0; neg = 0;
-		sign = 0; dot = 0; dwidth = 0; upper = 0;
-		cflag = 0; hflag = 0; jflag = 0; tflag = 0; zflag = 0;
-reswitch:	switch (ch = (unsigned char)*fmt++) {
-		case '.':
-			dot = 1;
-			goto reswitch;
-		case '#':
-			sharpflag = 1;
-			goto reswitch;
-		case '+':
-			sign = 1;
-			goto reswitch;
-		case '-':
-			ladjust = 1;
-			goto reswitch;
-		case '%':
-			PCHAR(ch);
-			break;
-		case '*':
-			if (!dot) {
-				width = va_arg(ap, int);
-				if (width < 0) {
-					ladjust = !ladjust;
-					width = -width;
-				}
-			} else {
-				dwidth = va_arg(ap, int);
-			}
-			goto reswitch;
-		case '0':
-			if (!dot) {
-				padc = '0';
-				goto reswitch;
-			}
-		case '1': case '2': case '3': case '4':
-		case '5': case '6': case '7': case '8': case '9':
-				for (n = 0;; ++fmt) {
-					n = n * 10 + ch - '0';
-					ch = *fmt;
-					if (ch < '0' || ch > '9')
-						break;
-				}
-			if (dot)
-				dwidth = n;
-			else
-				width = n;
-			goto reswitch;
-		case 'b':
-			num = (unsigned int)va_arg(ap, int);
-			p = va_arg(ap, char *);
-			for (q = ksprintn(nbuf, num, *p++, NULL, 0); *q;)
-				PCHAR(*q--);
-
-			if (num == 0)
-				break;
-
-			for (tmp = 0; *p;) {
-				n = *p++;
-				if (num & (1 << (n - 1))) {
-					PCHAR(tmp ? ',' : '<');
-					for (; (n = *p) > ' '; ++p)
-						PCHAR(n);
-					tmp = 1;
-				} else
-					for (; *p > ' '; ++p)
-						continue;
-			}
-			if (tmp)
-				PCHAR('>');
-			break;
-		case 'c':
-			PCHAR(va_arg(ap, int));
-			break;
-		case 'D':
-			up = va_arg(ap, unsigned char *);
-			p = va_arg(ap, char *);
-			if (!width)
-				width = 16;
-			while(width--) {
-				PCHAR(hex2ascii(*up >> 4));
-				PCHAR(hex2ascii(*up & 0x0f));
-				up++;
-				if (width)
-					for (q=p;*q;q++)
-						PCHAR(*q);
-			}
-			break;
-		case 'd':
-		case 'i':
-			base = 10;
-			sign = 1;
-			goto handle_sign;
-		case 'h':
-			if (hflag) {
-				hflag = 0;
-				cflag = 1;
-			} else
-				hflag = 1;
-			goto reswitch;
-		case 'j':
-			jflag = 1;
-			goto reswitch;
-		case 'l':
-			if (lflag) {
-				lflag = 0;
-				qflag = 1;
-			} else
-				lflag = 1;
-			goto reswitch;
-		case 'n':
-			if (jflag)
-				*(va_arg(ap, intmax_t *)) = retval;
-			else if (qflag)
-				*(va_arg(ap, int64_t *)) = retval;
-			else if (lflag)
-				*(va_arg(ap, long *)) = retval;
-			else if (zflag)
-				*(va_arg(ap, size_t *)) = retval;
-			else if (hflag)
-				*(va_arg(ap, short *)) = retval;
-			else if (cflag)
-				*(va_arg(ap, char *)) = retval;
-			else
-				*(va_arg(ap, int *)) = retval;
-			break;
-		case 'o':
-			base = 8;
-			goto handle_nosign;
-		case 'p':
-			base = 16;
-			sharpflag = (width == 0);
-			sign = 0;
-			num = (uintptr_t)va_arg(ap, void *);
-			goto number;
-		case 'q':
-			qflag = 1;
-			goto reswitch;
-		case 'r':
-			base = radix;
-			if (sign)
-				goto handle_sign;
-			goto handle_nosign;
-		case 's':
-			p = va_arg(ap, char *);
-			if (p == NULL)
-				p = "(null)";
-			if (!dot)
-				n = (int)strlen (p);
-			else
-				for (n = 0; n < dwidth && p[n]; n++)
-					continue;
-
-			width -= n;
-
-			if (!ladjust && width > 0)
-				while (width--)
-					PCHAR(padc);
-			while (n--)
-				PCHAR(*p++);
-			if (ladjust && width > 0)
-				while (width--)
-					PCHAR(padc);
-			break;
-		case 't':
-			tflag = 1;
-			goto reswitch;
-		case 'u':
-			base = 10;
-			goto handle_nosign;
-		case 'X':
-			upper = 1;
-		case 'x':
-			base = 16;
-			goto handle_nosign;
-		case 'y':
-			base = 16;
-			sign = 1;
-			goto handle_sign;
-		case 'z':
-			zflag = 1;
-			goto reswitch;
-handle_nosign:
-			sign = 0;
-			if (jflag)
-				num = va_arg(ap, uintmax_t);
-			else if (qflag)
-				num = va_arg(ap, uint64_t);
-			else if (tflag)
-				num = va_arg(ap, ptrdiff_t);
-			else if (lflag)
-				num = va_arg(ap, unsigned long);
-			else if (zflag)
-				num = va_arg(ap, size_t);
-			else if (hflag)
-				num = (unsigned short)va_arg(ap, int);
-			else if (cflag)
-				num = (unsigned char)va_arg(ap, int);
-			else
-				num = va_arg(ap, unsigned int);
-			goto number;
-handle_sign:
-			if (jflag)
-				num = va_arg(ap, intmax_t);
-			else if (qflag)
-				num = va_arg(ap, int64_t);
-			else if (tflag)
-				num = va_arg(ap, ptrdiff_t);
-			else if (lflag)
-				num = va_arg(ap, long);
-			else if (zflag)
-				num = va_arg(ap, ssize_t);
-			else if (hflag)
-				num = (short)va_arg(ap, int);
-			else if (cflag)
-				num = (char)va_arg(ap, int);
-			else
-				num = va_arg(ap, int);
-number:
-			if (sign && (intmax_t)num < 0) {
-				neg = 1;
-				num = -(intmax_t)num;
-			}
-			p = ksprintn(nbuf, num, base, &n, upper);
-			tmp = 0;
-			if (sharpflag && num != 0) {
-				if (base == 8)
-					tmp++;
-				else if (base == 16)
-					tmp += 2;
-			}
-			if (neg)
-				tmp++;
-
-			if (!ladjust && padc == '0')
-				dwidth = width - tmp;
-			width -= tmp + imax(dwidth, n);
-			dwidth -= n;
-			if (!ladjust)
-				while (width-- > 0)
-					PCHAR(' ');
-			if (neg)
-				PCHAR('-');
-			if (sharpflag && num != 0) {
-				if (base == 8) {
-					PCHAR('0');
-				} else if (base == 16) {
-					PCHAR('0');
-					PCHAR('x');
-				}
-			}
-			while (dwidth-- > 0)
-				PCHAR('0');
-
-			while (*p)
-				PCHAR(*p--);
-
-			if (ladjust)
-				while (width-- > 0)
-					PCHAR(' ');
-
-			break;
-		default:
-			while (percent < fmt)
-				PCHAR(*percent++);
-			/*
-			 * Since we ignore an formatting argument it is no
-			 * longer safe to obey the remaining formatting
-			 * arguments as the arguments will no longer match
-			 * the format specs.
-			 */
-			stop = 1;
-			break;
-		}
-	}
-#undef PCHAR
-}
 #else /* defined(USE_ELF) */
 #error not supported
 #endif
diff --git a/addr2line.h b/addr2line.h
index f09b665800..ff8e476b92 100644
--- a/addr2line.h
+++ b/addr2line.h
@@ -12,8 +12,10 @@
 
 #if (defined(USE_ELF) || defined(HAVE_MACH_O_LOADER_H))
 
+#include <stdio.h>
+
 void
-rb_dump_backtrace_with_lines(int num_traces, void **traces);
+rb_dump_backtrace_with_lines(int num_traces, void **traces, FILE *errout);
 
 #endif /* USE_ELF */
 
diff --git a/array.c b/array.c
index 793a53f17b..b471823876 100644
--- a/array.c
+++ b/array.c
@@ -27,8 +27,10 @@
 #include "probes.h"
 #include "ruby/encoding.h"
 #include "ruby/st.h"
+#include "ruby/thread.h"
 #include "ruby/util.h"
-#include "transient_heap.h"
+#include "ruby/ractor.h"
+#include "vm_core.h"
 #include "builtin.h"
 
 #if !ARRAY_DEBUG
@@ -38,22 +40,18 @@
 #include "ruby_assert.h"
 
 VALUE rb_cArray;
+VALUE rb_cArray_empty_frozen;
 
 /* Flags of RArray
  *
+ * 0:   RARRAY_SHARED_FLAG (equal to ELTS_SHARED)
+ *          The array is shared. The buffer this array points to is owned by
+ *          another array (the shared root).
  * 1:   RARRAY_EMBED_FLAG
  *          The array is embedded (its contents follow the header, rather than
  *          being on a separately allocated buffer).
- * 2:   RARRAY_SHARED_FLAG (equal to ELTS_SHARED)
- *          The array is shared. The buffer this array points to is owned by
- *          another array (the shared root).
- * if USE_RVARGC
  * 3-9: RARRAY_EMBED_LEN
  *          The length of the array when RARRAY_EMBED_FLAG is set.
- * else
- * 3-4: RARRAY_EMBED_LEN
- *          The length of the array when RARRAY_EMBED_FLAG is set.
- * endif
  * 12:  RARRAY_SHARED_ROOT_FLAG
  *          The array is a shared root that does reference counting. The buffer
  *          this array points to is owned by this array but may be pointed to
@@ -63,8 +61,6 @@ VALUE rb_cArray;
  *                they cannot be modified. Not updating the reference count
  *                improves copy-on-write performance. Their reference count is
  *                assumed to be infinity.
- * 13:  RARRAY_TRANSIENT_FLAG
- *          The buffer of the array is allocated on the transient heap.
  * 14:  RARRAY_PTR_IN_USE_FLAG
  *          The buffer of the array is in use. This is only used during
  *          debugging.
@@ -84,48 +80,49 @@ should_be_T_ARRAY(VALUE ary)
     return RB_TYPE_P(ary, T_ARRAY);
 }
 
-#define ARY_HEAP_PTR(a) (assert(!ARY_EMBED_P(a)), RARRAY(a)->as.heap.ptr)
-#define ARY_HEAP_LEN(a) (assert(!ARY_EMBED_P(a)), RARRAY(a)->as.heap.len)
-#define ARY_HEAP_CAPA(a) (assert(!ARY_EMBED_P(a)), assert(!ARY_SHARED_ROOT_P(a)), \
+#define ARY_HEAP_PTR(a) (RUBY_ASSERT(!ARY_EMBED_P(a)), RARRAY(a)->as.heap.ptr)
+#define ARY_HEAP_LEN(a) (RUBY_ASSERT(!ARY_EMBED_P(a)), RARRAY(a)->as.heap.len)
+#define ARY_HEAP_CAPA(a) (RUBY_ASSERT(!ARY_EMBED_P(a)), RUBY_ASSERT(!ARY_SHARED_ROOT_P(a)), \
                           RARRAY(a)->as.heap.aux.capa)
 
-#define ARY_EMBED_PTR(a) (assert(ARY_EMBED_P(a)), RARRAY(a)->as.ary)
+#define ARY_EMBED_PTR(a) (RUBY_ASSERT(ARY_EMBED_P(a)), RARRAY(a)->as.ary)
 #define ARY_EMBED_LEN(a) \
-    (assert(ARY_EMBED_P(a)), \
+    (RUBY_ASSERT(ARY_EMBED_P(a)), \
      (long)((RBASIC(a)->flags >> RARRAY_EMBED_LEN_SHIFT) & \
          (RARRAY_EMBED_LEN_MASK >> RARRAY_EMBED_LEN_SHIFT)))
-#define ARY_HEAP_SIZE(a) (assert(!ARY_EMBED_P(a)), assert(ARY_OWNS_HEAP_P(a)), ARY_CAPA(a) * sizeof(VALUE))
+#define ARY_HEAP_SIZE(a) (RUBY_ASSERT(!ARY_EMBED_P(a)), RUBY_ASSERT(ARY_OWNS_HEAP_P(a)), ARY_CAPA(a) * sizeof(VALUE))
 
-#define ARY_OWNS_HEAP_P(a) (assert(should_be_T_ARRAY((VALUE)(a))), \
+#define ARY_OWNS_HEAP_P(a) (RUBY_ASSERT(should_be_T_ARRAY((VALUE)(a))), \
                             !FL_TEST_RAW((a), RARRAY_SHARED_FLAG|RARRAY_EMBED_FLAG))
 
 #define FL_SET_EMBED(a) do { \
-    assert(!ARY_SHARED_P(a)); \
+    RUBY_ASSERT(!ARY_SHARED_P(a)); \
     FL_SET((a), RARRAY_EMBED_FLAG); \
-    RARY_TRANSIENT_UNSET(a); \
     ary_verify(a); \
 } while (0)
 
 #define FL_UNSET_EMBED(ary) FL_UNSET((ary), RARRAY_EMBED_FLAG|RARRAY_EMBED_LEN_MASK)
 #define FL_SET_SHARED(ary) do { \
-    assert(!ARY_EMBED_P(ary)); \
+    RUBY_ASSERT(!ARY_EMBED_P(ary)); \
     FL_SET((ary), RARRAY_SHARED_FLAG); \
 } while (0)
 #define FL_UNSET_SHARED(ary) FL_UNSET((ary), RARRAY_SHARED_FLAG)
 
+#define ARY_SET_PTR_FORCE(ary, p) \
+    (RARRAY(ary)->as.heap.ptr = (p))
 #define ARY_SET_PTR(ary, p) do { \
-    assert(!ARY_EMBED_P(ary)); \
-    assert(!OBJ_FROZEN(ary)); \
-    RARRAY(ary)->as.heap.ptr = (p); \
+    RUBY_ASSERT(!ARY_EMBED_P(ary)); \
+    RUBY_ASSERT(!OBJ_FROZEN(ary)); \
+    ARY_SET_PTR_FORCE(ary, p); \
 } while (0)
 #define ARY_SET_EMBED_LEN(ary, n) do { \
     long tmp_n = (n); \
-    assert(ARY_EMBED_P(ary)); \
+    RUBY_ASSERT(ARY_EMBED_P(ary)); \
     RBASIC(ary)->flags &= ~RARRAY_EMBED_LEN_MASK; \
     RBASIC(ary)->flags |= (tmp_n) << RARRAY_EMBED_LEN_SHIFT; \
 } while (0)
 #define ARY_SET_HEAP_LEN(ary, n) do { \
-    assert(!ARY_EMBED_P(ary)); \
+    RUBY_ASSERT(!ARY_EMBED_P(ary)); \
     RARRAY(ary)->as.heap.len = (n); \
 } while (0)
 #define ARY_SET_LEN(ary, n) do { \
@@ -135,15 +132,15 @@ should_be_T_ARRAY(VALUE ary)
     else { \
         ARY_SET_HEAP_LEN((ary), (n)); \
     } \
-    assert(RARRAY_LEN(ary) == (n)); \
+    RUBY_ASSERT(RARRAY_LEN(ary) == (n)); \
 } while (0)
 #define ARY_INCREASE_PTR(ary, n) do  { \
-    assert(!ARY_EMBED_P(ary)); \
-    assert(!OBJ_FROZEN(ary)); \
+    RUBY_ASSERT(!ARY_EMBED_P(ary)); \
+    RUBY_ASSERT(!OBJ_FROZEN(ary)); \
     RARRAY(ary)->as.heap.ptr += (n); \
 } while (0)
 #define ARY_INCREASE_LEN(ary, n) do  { \
-    assert(!OBJ_FROZEN(ary)); \
+    RUBY_ASSERT(!OBJ_FROZEN(ary)); \
     if (ARY_EMBED_P(ary)) { \
         ARY_SET_EMBED_LEN((ary), RARRAY_LEN(ary)+(n)); \
     } \
@@ -154,42 +151,33 @@ should_be_T_ARRAY(VALUE ary)
 
 #define ARY_CAPA(ary) (ARY_EMBED_P(ary) ? ary_embed_capa(ary) : \
                        ARY_SHARED_ROOT_P(ary) ? RARRAY_LEN(ary) : ARY_HEAP_CAPA(ary))
+#define ARY_SET_CAPA_FORCE(ary, n) \
+    RARRAY(ary)->as.heap.aux.capa = (n);
 #define ARY_SET_CAPA(ary, n) do { \
-    assert(!ARY_EMBED_P(ary)); \
-    assert(!ARY_SHARED_P(ary)); \
-    assert(!OBJ_FROZEN(ary)); \
-    RARRAY(ary)->as.heap.aux.capa = (n); \
-} while (0)
-
-#define ARY_SET_SHARED(ary, value) do { \
-    const VALUE _ary_ = (ary); \
-    const VALUE _value_ = (value); \
-    assert(!ARY_EMBED_P(_ary_)); \
-    assert(ARY_SHARED_P(_ary_)); \
-    assert(!OBJ_FROZEN(_ary_)); \
-    assert(ARY_SHARED_ROOT_P(_value_) || OBJ_FROZEN(_value_)); \
-    RB_OBJ_WRITE(_ary_, &RARRAY(_ary_)->as.heap.aux.shared_root, _value_); \
+    RUBY_ASSERT(!ARY_EMBED_P(ary)); \
+    RUBY_ASSERT(!ARY_SHARED_P(ary)); \
+    RUBY_ASSERT(!OBJ_FROZEN(ary)); \
+    ARY_SET_CAPA_FORCE(ary, n); \
 } while (0)
 
 #define ARY_SHARED_ROOT_OCCUPIED(ary) (!OBJ_FROZEN(ary) && ARY_SHARED_ROOT_REFCNT(ary) == 1)
 #define ARY_SET_SHARED_ROOT_REFCNT(ary, value) do { \
-    assert(ARY_SHARED_ROOT_P(ary)); \
-    assert(!OBJ_FROZEN(ary)); \
-    assert((value) >= 0); \
+    RUBY_ASSERT(ARY_SHARED_ROOT_P(ary)); \
+    RUBY_ASSERT(!OBJ_FROZEN(ary)); \
+    RUBY_ASSERT((value) >= 0); \
     RARRAY(ary)->as.heap.aux.capa = (value); \
 } while (0)
 #define FL_SET_SHARED_ROOT(ary) do { \
-    assert(!OBJ_FROZEN(ary)); \
-    assert(!ARY_EMBED_P(ary)); \
-    assert(!RARRAY_TRANSIENT_P(ary)); \
+    RUBY_ASSERT(!OBJ_FROZEN(ary)); \
+    RUBY_ASSERT(!ARY_EMBED_P(ary)); \
     FL_SET((ary), RARRAY_SHARED_ROOT_FLAG); \
 } while (0)
 
 static inline void
 ARY_SET(VALUE a, long i, VALUE v)
 {
-    assert(!ARY_SHARED_P(a));
-    assert(!OBJ_FROZEN(a));
+    RUBY_ASSERT(!ARY_SHARED_P(a));
+    RUBY_ASSERT(!OBJ_FROZEN(a));
 
     RARRAY_ASET(a, i, v);
 }
@@ -198,36 +186,37 @@ ARY_SET(VALUE a, long i, VALUE v)
 static long
 ary_embed_capa(VALUE ary)
 {
-#if USE_RVARGC
     size_t size = rb_gc_obj_slot_size(ary) - offsetof(struct RArray, as.ary);
-    assert(size % sizeof(VALUE) == 0);
+    RUBY_ASSERT(size % sizeof(VALUE) == 0);
     return size / sizeof(VALUE);
-#else
-    return RARRAY_EMBED_LEN_MAX;
-#endif
 }
 
 static size_t
 ary_embed_size(long capa)
 {
-    return offsetof(struct RArray, as.ary) + (sizeof(VALUE) * capa);
+    size_t size = offsetof(struct RArray, as.ary) + (sizeof(VALUE) * capa);
+    if (size < sizeof(struct RArray)) size = sizeof(struct RArray);
+    return size;
 }
 
 static bool
 ary_embeddable_p(long capa)
 {
-#if USE_RVARGC
     return rb_gc_size_allocatable_p(ary_embed_size(capa));
-#else
-    return capa <= RARRAY_EMBED_LEN_MAX;
-#endif
 }
 
 bool
 rb_ary_embeddable_p(VALUE ary)
 {
-    // if the array is shared or a shared root then it's not moveable
-    return !(ARY_SHARED_P(ary) || ARY_SHARED_ROOT_P(ary));
+    /* An array cannot be turned embeddable when the array is:
+     *  - Shared root: other objects may point to the buffer of this array
+     *    so we cannot make it embedded.
+     *  - Frozen: this array may also be a shared root without the shared root
+     *    flag.
+     *  - Shared: we don't want to re-embed an array that points to a shared
+     *    root (to save memory).
+     */
+    return !(ARY_SHARED_ROOT_P(ary) || OBJ_FROZEN(ary) || ARY_SHARED_P(ary));
 }
 
 size_t
@@ -242,7 +231,7 @@ rb_ary_size_as_embedded(VALUE ary)
         real_size = ary_embed_size(ARY_HEAP_CAPA(ary));
     }
     else {
-        real_size = sizeof(struct RString);
+        real_size = sizeof(struct RArray);
     }
     return real_size;
 }
@@ -254,25 +243,23 @@ rb_ary_size_as_embedded(VALUE ary)
 static VALUE
 ary_verify_(VALUE ary, const char *file, int line)
 {
-    assert(RB_TYPE_P(ary, T_ARRAY));
+    RUBY_ASSERT(RB_TYPE_P(ary, T_ARRAY));
 
     if (ARY_SHARED_P(ary)) {
         VALUE root = ARY_SHARED_ROOT(ary);
         const VALUE *ptr = ARY_HEAP_PTR(ary);
-        const VALUE *root_ptr = RARRAY_CONST_PTR_TRANSIENT(root);
+        const VALUE *root_ptr = RARRAY_CONST_PTR(root);
         long len = ARY_HEAP_LEN(ary), root_len = RARRAY_LEN(root);
-        assert(ARY_SHARED_ROOT_P(root) || OBJ_FROZEN(root));
-        assert(root_ptr <= ptr && ptr + len <= root_ptr + root_len);
+        RUBY_ASSERT(ARY_SHARED_ROOT_P(root) || OBJ_FROZEN(root));
+        RUBY_ASSERT(root_ptr <= ptr && ptr + len <= root_ptr + root_len);
         ary_verify(root);
     }
     else if (ARY_EMBED_P(ary)) {
-        assert(!RARRAY_TRANSIENT_P(ary));
-        assert(!ARY_SHARED_P(ary));
-        assert(RARRAY_LEN(ary) <= ary_embed_capa(ary));
+        RUBY_ASSERT(!ARY_SHARED_P(ary));
+        RUBY_ASSERT(RARRAY_LEN(ary) <= ary_embed_capa(ary));
     }
     else {
-#if 1
-        const VALUE *ptr = RARRAY_CONST_PTR_TRANSIENT(ary);
+        const VALUE *ptr = RARRAY_CONST_PTR(ary);
         long i, len = RARRAY_LEN(ary);
         volatile VALUE v;
         if (len > 1) len = 1; /* check only HEAD */
@@ -280,25 +267,10 @@ ary_verify_(VALUE ary, const char *file, int line)
             v = ptr[i]; /* access check */
         }
         v = v;
-#endif
     }
 
-#if USE_TRANSIENT_HEAP
-    if (RARRAY_TRANSIENT_P(ary)) {
-        assert(rb_transient_heap_managed_ptr_p(RARRAY_CONST_PTR_TRANSIENT(ary)));
-    }
-#endif
-
-    rb_transient_heap_verify();
-
     return ary;
 }
-
-void
-rb_ary_verify(VALUE ary)
-{
-    ary_verify(ary);
-}
 #else
 #define ary_verify(ary) ((void)0)
 #endif
@@ -309,7 +281,7 @@ rb_ary_ptr_use_start(VALUE ary)
 #if ARRAY_DEBUG
     FL_SET_RAW(ary, RARRAY_PTR_IN_USE_FLAG);
 #endif
-    return (VALUE *)RARRAY_CONST_PTR_TRANSIENT(ary);
+    return (VALUE *)RARRAY_CONST_PTR(ary);
 }
 
 void
@@ -331,7 +303,7 @@ rb_mem_clear(VALUE *mem, long size)
 static void
 ary_mem_clear(VALUE ary, long beg, long size)
 {
-    RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+    RARRAY_PTR_USE(ary, ptr, {
         rb_mem_clear(ptr + beg, size);
     });
 }
@@ -347,7 +319,7 @@ memfill(register VALUE *mem, register long size, register VALUE val)
 static void
 ary_memfill(VALUE ary, long beg, long size, VALUE val)
 {
-    RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+    RARRAY_PTR_USE(ary, ptr, {
         memfill(ptr + beg, size, val);
         RB_OBJ_WRITTEN(ary, Qundef, val);
     });
@@ -356,17 +328,17 @@ ary_memfill(VALUE ary, long beg, long size, VALUE val)
 static void
 ary_memcpy0(VALUE ary, long beg, long argc, const VALUE *argv, VALUE buff_owner_ary)
 {
-    assert(!ARY_SHARED_P(buff_owner_ary));
+    RUBY_ASSERT(!ARY_SHARED_P(buff_owner_ary));
 
     if (argc > (int)(128/sizeof(VALUE)) /* is magic number (cache line size) */) {
         rb_gc_writebarrier_remember(buff_owner_ary);
-        RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+        RARRAY_PTR_USE(ary, ptr, {
             MEMCPY(ptr+beg, argv, VALUE, argc);
         });
     }
     else {
         int i;
-        RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+        RARRAY_PTR_USE(ary, ptr, {
             for (i=0; i<argc; i++) {
                 RB_OBJ_WRITE(buff_owner_ary, &ptr[i+beg], argv[i]);
             }
@@ -381,138 +353,46 @@ ary_memcpy(VALUE ary, long beg, long argc, const VALUE *argv)
 }
 
 static VALUE *
-ary_heap_alloc(VALUE ary, size_t capa)
+ary_heap_alloc_buffer(size_t capa)
 {
-    VALUE *ptr = rb_transient_heap_alloc(ary, sizeof(VALUE) * capa);
-
-    if (ptr != NULL) {
-        RARY_TRANSIENT_SET(ary);
-    }
-    else {
-        RARY_TRANSIENT_UNSET(ary);
-        ptr = ALLOC_N(VALUE, capa);
-    }
-
-    return ptr;
+    return ALLOC_N(VALUE, capa);
 }
 
 static void
 ary_heap_free_ptr(VALUE ary, const VALUE *ptr, long size)
 {
-    if (RARRAY_TRANSIENT_P(ary)) {
-        /* ignore it */
-    }
-    else {
-        ruby_sized_xfree((void *)ptr, size);
-    }
+    ruby_sized_xfree((void *)ptr, size);
 }
 
 static void
 ary_heap_free(VALUE ary)
 {
-    if (RARRAY_TRANSIENT_P(ary)) {
-        RARY_TRANSIENT_UNSET(ary);
-    }
-    else {
-        ary_heap_free_ptr(ary, ARY_HEAP_PTR(ary), ARY_HEAP_SIZE(ary));
-    }
+    ary_heap_free_ptr(ary, ARY_HEAP_PTR(ary), ARY_HEAP_SIZE(ary));
 }
 
 static size_t
 ary_heap_realloc(VALUE ary, size_t new_capa)
 {
-    size_t alloc_capa = new_capa;
-    size_t old_capa = ARY_HEAP_CAPA(ary);
-
-    if (RARRAY_TRANSIENT_P(ary)) {
-        if (new_capa <= old_capa) {
-            /* do nothing */
-            alloc_capa = old_capa;
-        }
-        else {
-            VALUE *new_ptr = rb_transient_heap_alloc(ary, sizeof(VALUE) * new_capa);
-
-            if (new_ptr == NULL) {
-                new_ptr = ALLOC_N(VALUE, new_capa);
-                RARY_TRANSIENT_UNSET(ary);
-            }
-
-            MEMCPY(new_ptr, ARY_HEAP_PTR(ary), VALUE, old_capa);
-            ARY_SET_PTR(ary, new_ptr);
-        }
-    }
-    else {
-        SIZED_REALLOC_N(RARRAY(ary)->as.heap.ptr, VALUE, new_capa, old_capa);
-    }
+    RUBY_ASSERT(!OBJ_FROZEN(ary));
+    SIZED_REALLOC_N(RARRAY(ary)->as.heap.ptr, VALUE, new_capa, ARY_HEAP_CAPA(ary));
     ary_verify(ary);
 
-    return alloc_capa;
-}
-
-#if USE_TRANSIENT_HEAP
-static inline void
-rb_ary_transient_heap_evacuate_(VALUE ary, int transient, int promote)
-{
-    if (transient) {
-        assert(!ARY_SHARED_ROOT_P(ary));
-
-        VALUE *new_ptr;
-        const VALUE *old_ptr = ARY_HEAP_PTR(ary);
-        long capa = ARY_HEAP_CAPA(ary);
-
-        assert(ARY_OWNS_HEAP_P(ary));
-        assert(RARRAY_TRANSIENT_P(ary));
-        assert(!ARY_PTR_USING_P(ary));
-
-        if (promote) {
-            new_ptr = ALLOC_N(VALUE, capa);
-            RARY_TRANSIENT_UNSET(ary);
-        }
-        else {
-            new_ptr = ary_heap_alloc(ary, capa);
-        }
-
-        MEMCPY(new_ptr, old_ptr, VALUE, capa);
-        /* do not use ARY_SET_PTR() because they assert !frozen */
-        RARRAY(ary)->as.heap.ptr = new_ptr;
-    }
-
-    ary_verify(ary);
-}
-
-void
-rb_ary_transient_heap_evacuate(VALUE ary, int promote)
-{
-    rb_ary_transient_heap_evacuate_(ary, RARRAY_TRANSIENT_P(ary), promote);
+    return new_capa;
 }
 
 void
-rb_ary_detransient(VALUE ary)
-{
-    assert(RARRAY_TRANSIENT_P(ary));
-    rb_ary_transient_heap_evacuate_(ary, TRUE, TRUE);
-}
-#else
-void
-rb_ary_detransient(VALUE ary)
-{
-    /* do nothing */
-}
-#endif
-
-void
 rb_ary_make_embedded(VALUE ary)
 {
-    assert(rb_ary_embeddable_p(ary));
+    RUBY_ASSERT(rb_ary_embeddable_p(ary));
     if (!ARY_EMBED_P(ary)) {
-        VALUE *buf = RARRAY_PTR(ary);
-        long len = RARRAY_LEN(ary);
+        const VALUE *buf = ARY_HEAP_PTR(ary);
+        long len = ARY_HEAP_LEN(ary);
 
         FL_SET_EMBED(ary);
         ARY_SET_EMBED_LEN(ary, len);
-        RARY_TRANSIENT_UNSET(ary);
 
-        memmove(RARRAY_PTR(ary), buf, len * sizeof(VALUE));
+        MEMCPY((void *)ARY_EMBED_PTR(ary), (void *)buf, VALUE, len);
+
         ary_heap_free_ptr(ary, buf, len * sizeof(VALUE));
     }
 }
@@ -520,15 +400,15 @@ rb_ary_make_embedded(VALUE ary)
 static void
 ary_resize_capa(VALUE ary, long capacity)
 {
-    assert(RARRAY_LEN(ary) <= capacity);
-    assert(!OBJ_FROZEN(ary));
-    assert(!ARY_SHARED_P(ary));
+    RUBY_ASSERT(RARRAY_LEN(ary) <= capacity);
+    RUBY_ASSERT(!OBJ_FROZEN(ary));
+    RUBY_ASSERT(!ARY_SHARED_P(ary));
 
     if (capacity > ary_embed_capa(ary)) {
         size_t new_capa = capacity;
         if (ARY_EMBED_P(ary)) {
             long len = ARY_EMBED_LEN(ary);
-            VALUE *ptr = ary_heap_alloc(ary, capacity);
+            VALUE *ptr = ary_heap_alloc_buffer(capacity);
 
             MEMCPY(ptr, ARY_EMBED_PTR(ary), VALUE, len);
             FL_UNSET_EMBED(ary);
@@ -563,9 +443,12 @@ ary_shrink_capa(VALUE ary)
 {
     long capacity = ARY_HEAP_LEN(ary);
     long old_capa = ARY_HEAP_CAPA(ary);
-    assert(!ARY_SHARED_P(ary));
-    assert(old_capa >= capacity);
-    if (old_capa > capacity) ary_heap_realloc(ary, capacity);
+    RUBY_ASSERT(!ARY_SHARED_P(ary));
+    RUBY_ASSERT(old_capa >= capacity);
+    if (old_capa > capacity) {
+        size_t new_capa = ary_heap_realloc(ary, capacity);
+        ARY_SET_CAPA(ary, new_capa);
+    }
 
     ary_verify(ary);
 }
@@ -623,7 +506,7 @@ rb_ary_increment_share(VALUE shared_root)
 {
     if (!OBJ_FROZEN(shared_root)) {
         long num = ARY_SHARED_ROOT_REFCNT(shared_root);
-        assert(num >= 0);
+        RUBY_ASSERT(num >= 0);
         ARY_SET_SHARED_ROOT_REFCNT(shared_root, num + 1);
     }
     return shared_root;
@@ -632,15 +515,22 @@ rb_ary_increment_share(VALUE shared_root)
 static void
 rb_ary_set_shared(VALUE ary, VALUE shared_root)
 {
+    RUBY_ASSERT(!ARY_EMBED_P(ary));
+    RUBY_ASSERT(!OBJ_FROZEN(ary));
+    RUBY_ASSERT(ARY_SHARED_ROOT_P(shared_root) || OBJ_FROZEN(shared_root));
+
     rb_ary_increment_share(shared_root);
     FL_SET_SHARED(ary);
+    RB_OBJ_WRITE(ary, &RARRAY(ary)->as.heap.aux.shared_root, shared_root);
+
     RB_DEBUG_COUNTER_INC(obj_ary_shared_create);
-    ARY_SET_SHARED(ary, shared_root);
 }
 
 static inline void
 rb_ary_modify_check(VALUE ary)
 {
+    RUBY_ASSERT(ruby_thread_has_gvl_p());
+
     rb_check_frozen(ary);
     ary_verify(ary);
 }
@@ -663,22 +553,22 @@ rb_ary_cancel_sharing(VALUE ary)
             ARY_SET_EMBED_LEN(ary, len);
         }
         else if (ARY_SHARED_ROOT_OCCUPIED(shared_root) && len > ((shared_len = RARRAY_LEN(shared_root))>>1)) {
-            long shift = RARRAY_CONST_PTR_TRANSIENT(ary) - RARRAY_CONST_PTR_TRANSIENT(shared_root);
+            long shift = RARRAY_CONST_PTR(ary) - RARRAY_CONST_PTR(shared_root);
             FL_UNSET_SHARED(ary);
-            ARY_SET_PTR(ary, RARRAY_CONST_PTR_TRANSIENT(shared_root));
+            ARY_SET_PTR(ary, RARRAY_CONST_PTR(shared_root));
             ARY_SET_CAPA(ary, shared_len);
-            RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+            RARRAY_PTR_USE(ary, ptr, {
                 MEMMOVE(ptr, ptr+shift, VALUE, len);
             });
             FL_SET_EMBED(shared_root);
             rb_ary_decrement_share(shared_root);
         }
         else {
-            VALUE *ptr = ary_heap_alloc(ary, len);
+            VALUE *ptr = ary_heap_alloc_buffer(len);
             MEMCPY(ptr, ARY_HEAP_PTR(ary), VALUE, len);
             rb_ary_unshare(ary);
-            ARY_SET_CAPA(ary, len);
-            ARY_SET_PTR(ary, ptr);
+            ARY_SET_CAPA_FORCE(ary, len);
+            ARY_SET_PTR_FORCE(ary, ptr);
         }
 
         rb_gc_writebarrier_remember(ary);
@@ -707,7 +597,7 @@ ary_ensure_room_for_push(VALUE ary, long add_len)
         if (new_len > ary_embed_capa(ary)) {
             VALUE shared_root = ARY_SHARED_ROOT(ary);
             if (ARY_SHARED_ROOT_OCCUPIED(shared_root)) {
-                if (ARY_HEAP_PTR(ary) - RARRAY_CONST_PTR_TRANSIENT(shared_root) + new_len <= RARRAY_LEN(shared_root)) {
+                if (ARY_HEAP_PTR(ary) - RARRAY_CONST_PTR(shared_root) + new_len <= RARRAY_LEN(shared_root)) {
                     rb_ary_modify_check(ary);
 
                     ary_verify(ary);
@@ -743,21 +633,32 @@ ary_ensure_room_for_push(VALUE ary, long add_len)
 
 /*
  *  call-seq:
- *    array.freeze -> self
+ *    freeze -> self
  *
- *  Freezes +self+; returns +self+:
+ *  Freezes +self+ (if not already frozen); returns +self+:
  *
  *    a = []
  *    a.frozen? # => false
  *    a.freeze
  *    a.frozen? # => true
  *
- *  An attempt to modify a frozen \Array raises FrozenError.
+ *  No further changes may be made to +self+;
+ *  raises FrozenError if a change is attempted.
+ *
+ *  Related: Kernel#frozen?.
  */
 
 VALUE
 rb_ary_freeze(VALUE ary)
 {
+    RUBY_ASSERT(RB_TYPE_P(ary, T_ARRAY));
+
+    if (OBJ_FROZEN(ary)) return ary;
+
+    if (!ARY_EMBED_P(ary) && !ARY_SHARED_P(ary) && !ARY_SHARED_ROOT_P(ary)) {
+        ary_shrink_capa(ary);
+    }
+
     return rb_obj_freeze(ary);
 }
 
@@ -784,13 +685,10 @@ static VALUE
 ary_alloc_embed(VALUE klass, long capa)
 {
     size_t size = ary_embed_size(capa);
-    assert(rb_gc_size_allocatable_p(size));
-#if !USE_RVARGC
-    assert(size <= sizeof(struct RArray));
-#endif
-    RVARGC_NEWOBJ_OF(ary, struct RArray, klass,
+    RUBY_ASSERT(rb_gc_size_allocatable_p(size));
+    NEWOBJ_OF(ary, struct RArray, klass,
                      T_ARRAY | RARRAY_EMBED_FLAG | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0),
-                     size);
+                     size, 0);
     /* Created array is:
      *   FL_SET_EMBED((VALUE)ary);
      *   ARY_SET_EMBED_LEN((VALUE)ary, 0);
@@ -801,9 +699,14 @@ ary_alloc_embed(VALUE klass, long capa)
 static VALUE
 ary_alloc_heap(VALUE klass)
 {
-    RVARGC_NEWOBJ_OF(ary, struct RArray, klass,
+    NEWOBJ_OF(ary, struct RArray, klass,
                      T_ARRAY | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0),
-                     sizeof(struct RArray));
+                     sizeof(struct RArray), 0);
+
+    ary->as.heap.len = 0;
+    ary->as.heap.aux.capa = 0;
+    ary->as.heap.ptr = NULL;
+
     return (VALUE)ary;
 }
 
@@ -817,7 +720,9 @@ empty_ary_alloc(VALUE klass)
 static VALUE
 ary_new(VALUE klass, long capa)
 {
-    VALUE ary,*ptr;
+    RUBY_ASSERT(ruby_thread_has_gvl_p());
+
+    VALUE ary;
 
     if (capa < 0) {
         rb_raise(rb_eArgError, "negative array size (or size too big)");
@@ -833,11 +738,10 @@ ary_new(VALUE klass, long capa)
     }
     else {
         ary = ary_alloc_heap(klass);
-        assert(!ARY_EMBED_P(ary));
-
-        ptr = ary_heap_alloc(ary, capa);
-        ARY_SET_PTR(ary, ptr);
         ARY_SET_CAPA(ary, capa);
+        RUBY_ASSERT(!ARY_EMBED_P(ary));
+
+        ARY_SET_PTR(ary, ary_heap_alloc_buffer(capa));
         ARY_SET_HEAP_LEN(ary, 0);
     }
 
@@ -875,7 +779,7 @@ VALUE
     return ary;
 }
 
-MJIT_FUNC_EXPORTED VALUE
+VALUE
 rb_ary_tmp_new_from_values(VALUE klass, long n, const VALUE *elts)
 {
     VALUE ary;
@@ -899,13 +803,10 @@ static VALUE
 ec_ary_alloc_embed(rb_execution_context_t *ec, VALUE klass, long capa)
 {
     size_t size = ary_embed_size(capa);
-    assert(rb_gc_size_allocatable_p(size));
-#if !USE_RVARGC
-    assert(size <= sizeof(struct RArray));
-#endif
-    RB_RVARGC_EC_NEWOBJ_OF(ec, ary, struct RArray, klass,
-                           T_ARRAY | RARRAY_EMBED_FLAG | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0),
-                           size);
+    RUBY_ASSERT(rb_gc_size_allocatable_p(size));
+    NEWOBJ_OF(ary, struct RArray, klass,
+            T_ARRAY | RARRAY_EMBED_FLAG | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0),
+            size, ec);
     /* Created array is:
      *   FL_SET_EMBED((VALUE)ary);
      *   ARY_SET_EMBED_LEN((VALUE)ary, 0);
@@ -916,16 +817,21 @@ ec_ary_alloc_embed(rb_execution_context_t *ec, VALUE klass, long capa)
 static VALUE
 ec_ary_alloc_heap(rb_execution_context_t *ec, VALUE klass)
 {
-    RB_RVARGC_EC_NEWOBJ_OF(ec, ary, struct RArray, klass,
-                           T_ARRAY | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0),
-                           sizeof(struct RArray));
+    NEWOBJ_OF(ary, struct RArray, klass,
+            T_ARRAY | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0),
+            sizeof(struct RArray), ec);
+
+    ary->as.heap.len = 0;
+    ary->as.heap.aux.capa = 0;
+    ary->as.heap.ptr = NULL;
+
     return (VALUE)ary;
 }
 
 static VALUE
 ec_ary_new(rb_execution_context_t *ec, VALUE klass, long capa)
 {
-    VALUE ary,*ptr;
+    VALUE ary;
 
     if (capa < 0) {
         rb_raise(rb_eArgError, "negative array size (or size too big)");
@@ -941,11 +847,10 @@ ec_ary_new(rb_execution_context_t *ec, VALUE klass, long capa)
     }
     else {
         ary = ec_ary_alloc_heap(ec, klass);
-        assert(!ARY_EMBED_P(ary));
-
-        ptr = ary_heap_alloc(ary, capa);
-        ARY_SET_PTR(ary, ptr);
         ARY_SET_CAPA(ary, capa);
+        RUBY_ASSERT(!ARY_EMBED_P(ary));
+
+        ARY_SET_PTR(ary, ary_heap_alloc_buffer(capa));
         ARY_SET_HEAP_LEN(ary, 0);
     }
 
@@ -970,7 +875,6 @@ VALUE
 rb_ary_hidden_new(long capa)
 {
     VALUE ary = ary_new(0, capa);
-    rb_ary_transient_heap_evacuate(ary, TRUE);
     return ary;
 }
 
@@ -993,13 +897,8 @@ rb_ary_free(VALUE ary)
             RB_DEBUG_COUNTER_INC(obj_ary_extracapa);
         }
 
-        if (RARRAY_TRANSIENT_P(ary)) {
-            RB_DEBUG_COUNTER_INC(obj_ary_transient);
-        }
-        else {
-            RB_DEBUG_COUNTER_INC(obj_ary_ptr);
-            ary_heap_free(ary);
-        }
+        RB_DEBUG_COUNTER_INC(obj_ary_ptr);
+        ary_heap_free(ary);
     }
     else {
         RB_DEBUG_COUNTER_INC(obj_ary_embed);
@@ -1013,7 +912,32 @@ rb_ary_free(VALUE ary)
     }
 }
 
-RUBY_FUNC_EXPORTED size_t
+static VALUE fake_ary_flags;
+
+static VALUE
+init_fake_ary_flags(void)
+{
+    struct RArray fake_ary = {0};
+    fake_ary.basic.flags = T_ARRAY;
+    VALUE ary = (VALUE)&fake_ary;
+    rb_ary_freeze(ary);
+    return fake_ary.basic.flags;
+}
+
+VALUE
+rb_setup_fake_ary(struct RArray *fake_ary, const VALUE *list, long len)
+{
+    fake_ary->basic.flags = fake_ary_flags;
+    RBASIC_CLEAR_CLASS((VALUE)fake_ary);
+
+    // bypass frozen checks
+    fake_ary->as.heap.ptr = list;
+    fake_ary->as.heap.len = len;
+    fake_ary->as.heap.aux.capa = len;
+    return (VALUE)fake_ary;
+}
+
+size_t
 rb_ary_memsize(VALUE ary)
 {
     if (ARY_OWNS_HEAP_P(ary)) {
@@ -1027,7 +951,6 @@ rb_ary_memsize(VALUE ary)
 static VALUE
 ary_make_shared(VALUE ary)
 {
-    assert(USE_RVARGC || !ARY_EMBED_P(ary));
     ary_verify(ary);
 
     if (ARY_SHARED_P(ary)) {
@@ -1037,44 +960,33 @@ ary_make_shared(VALUE ary)
         return ary;
     }
     else if (OBJ_FROZEN(ary)) {
-        if (!ARY_EMBED_P(ary)) {
-            rb_ary_transient_heap_evacuate(ary, TRUE);
-            ary_shrink_capa(ary);
-        }
         return ary;
     }
     else {
-        rb_ary_transient_heap_evacuate(ary, TRUE);
-
         long capa = ARY_CAPA(ary);
         long len = RARRAY_LEN(ary);
 
         /* Shared roots cannot be embedded because the reference count
          * (refcnt) is stored in as.heap.aux.capa. */
         VALUE shared = ary_alloc_heap(0);
+        FL_SET_SHARED_ROOT(shared);
 
         if (ARY_EMBED_P(ary)) {
-            /* Cannot use ary_heap_alloc because we don't want to allocate
-             * on the transient heap. */
-            VALUE *ptr = ALLOC_N(VALUE, capa);
+            VALUE *ptr = ary_heap_alloc_buffer(capa);
             ARY_SET_PTR(shared, ptr);
-            ary_memcpy(shared, 0, len, RARRAY_PTR(ary));
+            ary_memcpy(shared, 0, len, RARRAY_CONST_PTR(ary));
 
             FL_UNSET_EMBED(ary);
             ARY_SET_HEAP_LEN(ary, len);
             ARY_SET_PTR(ary, ptr);
         }
         else {
-            ARY_SET_PTR(shared, RARRAY_PTR(ary));
+            ARY_SET_PTR(shared, RARRAY_CONST_PTR(ary));
         }
 
         ARY_SET_LEN(shared, capa);
         ary_mem_clear(shared, len, capa - len);
-        FL_SET_SHARED_ROOT(shared);
-        ARY_SET_SHARED_ROOT_REFCNT(shared, 1);
-        FL_SET_SHARED(ary);
-        RB_DEBUG_COUNTER_INC(obj_ary_shared_create);
-        ARY_SET_SHARED(ary, shared);
+        rb_ary_set_shared(ary, shared);
 
         ary_verify(shared);
         ary_verify(ary);
@@ -1090,9 +1002,9 @@ ary_make_substitution(VALUE ary)
 
     if (ary_embeddable_p(len)) {
         VALUE subst = rb_ary_new_capa(len);
-        assert(ARY_EMBED_P(subst));
+        RUBY_ASSERT(ARY_EMBED_P(subst));
 
-        ary_memcpy(subst, 0, len, RARRAY_CONST_PTR_TRANSIENT(ary));
+        ary_memcpy(subst, 0, len, RARRAY_CONST_PTR(ary));
         ARY_SET_EMBED_LEN(subst, len);
         return subst;
     }
@@ -1120,7 +1032,7 @@ rb_check_array_type(VALUE ary)
     return rb_check_convert_type_with_id(ary, T_ARRAY, "Array", idTo_ary);
 }
 
-MJIT_FUNC_EXPORTED VALUE
+VALUE
 rb_check_to_array(VALUE ary)
 {
     return rb_check_convert_type_with_id(ary, T_ARRAY, "Array", idTo_a);
@@ -1136,14 +1048,18 @@ rb_to_array(VALUE ary)
  *  call-seq:
  *    Array.try_convert(object) -> object, new_array, or nil
  *
- *  If +object+ is an \Array object, returns +object+.
+ *  Attempts to return an array, based on the given +object+.
  *
- *  Otherwise if +object+ responds to <tt>:to_ary</tt>,
- *  calls <tt>object.to_ary</tt> and returns the result.
+ *  If +object+ is an array, returns +object+.
  *
- *  Returns +nil+ if +object+ does not respond to <tt>:to_ary</tt>
+ *  Otherwise if +object+ responds to <tt>:to_ary</tt>.
+ *  calls <tt>object.to_ary</tt>:
+ *  if the return value is an array or +nil+, returns that value;
+ *  if not, raises TypeError.
  *
- *  Raises an exception unless <tt>object.to_ary</tt> returns an \Array object.
+ *  Otherwise returns +nil+.
+ *
+ *  Related: see {Methods for Creating an Array}[rdoc-ref:Array@Methods+for+Creating+an+Array].
  */
 
 static VALUE
@@ -1180,48 +1096,51 @@ rb_ary_s_new(int argc, VALUE *argv, VALUE klass)
  *  call-seq:
  *    Array.new -> new_empty_array
  *    Array.new(array) -> new_array
- *    Array.new(size) -> new_array
- *    Array.new(size, default_value) -> new_array
- *    Array.new(size) {|index| ... } -> new_array
+ *    Array.new(size, default_value = nil) -> new_array
+ *    Array.new(size = 0) {|index| ... } -> new_array
  *
- *  Returns a new \Array.
+ *  Returns a new array.
  *
- *  With no block and no arguments, returns a new empty \Array object.
+ *  With no block and no argument given, returns a new empty array:
  *
- *  With no block and a single \Array argument +array+,
- *  returns a new \Array formed from +array+:
+ *    Array.new # => []
  *
- *    a = Array.new([:foo, 'bar', 2])
- *    a.class # => Array
- *    a # => [:foo, "bar", 2]
+ *  With no block and array argument given, returns a new array with the same elements:
+ *
+ *    Array.new([:foo, 'bar', 2]) # => [:foo, "bar", 2]
  *
- *  With no block and a single \Integer argument +size+,
- *  returns a new \Array of the given size
- *  whose elements are all +nil+:
+ *  With no block and integer argument given, returns a new array containing
+ *  that many instances of the given +default_value+:
  *
- *    a = Array.new(3)
- *    a # => [nil, nil, nil]
+ *    Array.new(0)    # => []
+ *    Array.new(3)    # => [nil, nil, nil]
+ *    Array.new(2, 3) # => [3, 3]
  *
- *  With no block and arguments +size+ and +default_value+,
- *  returns an \Array of the given size;
- *  each element is that same +default_value+:
+ *  With a block given, returns an array of the given +size+;
+ *  calls the block with each +index+ in the range <tt>(0...size)</tt>;
+ *  the element at that +index+ in the returned array is the blocks return value:
  *
- *    a = Array.new(3, 'x')
- *    a # => ['x', 'x', 'x']
+ *    Array.new(3)  {|index| "Element #{index}" } # => ["Element 0", "Element 1", "Element 2"]
  *
- *  With a block and argument +size+,
- *  returns an \Array of the given size;
- *  the block is called with each successive integer +index+;
- *  the element for that +index+ is the return value from the block:
+ *  A common pitfall for new Rubyists is providing an expression as +default_value+:
  *
- *    a = Array.new(3) {|index| "Element #{index}" }
- *    a # => ["Element 0", "Element 1", "Element 2"]
+ *    array = Array.new(2, {})
+ *    array # => [{}, {}]
+ *    array[0][:a] = 1
+ *    array # => [{a: 1}, {a: 1}], as array[0] and array[1] are same object
  *
- *  Raises ArgumentError if +size+ is negative.
+ *  If you want the elements of the array to be distinct, you should pass a block:
  *
- *  With a block and no argument,
- *  or a single argument +0+,
- *  ignores the block and returns a new empty \Array.
+ *    array = Array.new(2) { {} }
+ *    array # => [{}, {}]
+ *    array[0][:a] = 1
+ *    array # => [{a: 1}, {}], as array[0] and array[1] are different objects
+ *
+ *  Raises TypeError if the first argument is not either an array
+ *  or an {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects]).
+ *  Raises ArgumentError if the first argument is a negative integer.
+ *
+ *  Related: see {Methods for Creating an Array}[rdoc-ref:Array@Methods+for+Creating+an+Array].
  */
 
 static VALUE
@@ -1233,8 +1152,8 @@ rb_ary_initialize(int argc, VALUE *argv, VALUE ary)
     rb_ary_modify(ary);
     if (argc == 0) {
         rb_ary_reset(ary);
-        assert(ARY_EMBED_P(ary));
-        assert(ARY_EMBED_LEN(ary) == 0);
+        RUBY_ASSERT(ARY_EMBED_P(ary));
+        RUBY_ASSERT(ARY_EMBED_LEN(ary) == 0);
         if (rb_block_given_p()) {
             rb_warning("given block not used");
         }
@@ -1279,11 +1198,13 @@ rb_ary_initialize(int argc, VALUE *argv, VALUE ary)
 }
 
 /*
- * Returns a new array populated with the given objects.
+ * Returns a new array, populated with the given objects:
+ *
+ *   Array[1, 'a', /^A/]    # => [1, "a", /^A/]
+ *   Array[]                # => []
+ *   Array.[](1, 'a', /^A/) # => [1, "a", /^A/]
  *
- *   Array.[]( 1, 'a', /^A/)  # => [1, "a", /^A/]
- *   Array[ 1, 'a', /^A/ ]    # => [1, "a", /^A/]
- *   [ 1, 'a', /^A/ ]         # => [1, "a", /^A/]
+ * Related: see {Methods for Creating an Array}[rdoc-ref:Array@Methods+for+Creating+an+Array].
  */
 
 static VALUE
@@ -1331,25 +1252,26 @@ rb_ary_store(VALUE ary, long idx, VALUE val)
 static VALUE
 ary_make_partial(VALUE ary, VALUE klass, long offset, long len)
 {
-    assert(offset >= 0);
-    assert(len >= 0);
-    assert(offset+len <= RARRAY_LEN(ary));
+    RUBY_ASSERT(offset >= 0);
+    RUBY_ASSERT(len >= 0);
+    RUBY_ASSERT(offset+len <= RARRAY_LEN(ary));
 
-    const size_t rarray_embed_capa_max = (sizeof(struct RArray) - offsetof(struct RArray, as.ary)) / sizeof(VALUE);
-
-    if ((size_t)len <= rarray_embed_capa_max && ary_embeddable_p(len)) {
-        VALUE result = ary_alloc_embed(klass, len);
-        ary_memcpy(result, 0, len, RARRAY_CONST_PTR_TRANSIENT(ary) + offset);
+    VALUE result = ary_alloc_heap(klass);
+    size_t embed_capa = ary_embed_capa(result);
+    if ((size_t)len <= embed_capa) {
+        FL_SET_EMBED(result);
+        ary_memcpy(result, 0, len, RARRAY_CONST_PTR(ary) + offset);
         ARY_SET_EMBED_LEN(result, len);
-        return result;
     }
     else {
-        VALUE result = ary_alloc_heap(klass);
-        assert(!ARY_EMBED_P(result));
-
         VALUE shared = ary_make_shared(ary);
 
-        ARY_SET_PTR(result, RARRAY_CONST_PTR_TRANSIENT(ary));
+        /* The ary_make_shared call may allocate, which can trigger a GC
+         * compaction. This can cause the array to be embedded because it has
+         * a length of 0. */
+        FL_UNSET_EMBED(result);
+
+        ARY_SET_PTR(result, RARRAY_CONST_PTR(ary));
         ARY_SET_LEN(result, RARRAY_LEN(ary));
         rb_ary_set_shared(result, shared);
 
@@ -1357,25 +1279,27 @@ ary_make_partial(VALUE ary, VALUE klass, long offset, long len)
         ARY_SET_LEN(result, len);
 
         ary_verify(shared);
-        ary_verify(result);
-        return result;
     }
+
+    ary_verify(result);
+    return result;
 }
 
 static VALUE
 ary_make_partial_step(VALUE ary, VALUE klass, long offset, long len, long step)
 {
-    assert(offset >= 0);
-    assert(len >= 0);
-    assert(offset+len <= RARRAY_LEN(ary));
-    assert(step != 0);
+    RUBY_ASSERT(offset >= 0);
+    RUBY_ASSERT(len >= 0);
+    RUBY_ASSERT(offset+len <= RARRAY_LEN(ary));
+    RUBY_ASSERT(step != 0);
 
-    const VALUE *values = RARRAY_CONST_PTR_TRANSIENT(ary);
     const long orig_len = len;
 
     if (step > 0 && step >= len) {
         VALUE result = ary_new(klass, 1);
         VALUE *ptr = (VALUE *)ARY_EMBED_PTR(result);
+        const VALUE *values = RARRAY_CONST_PTR(ary);
+
         RB_OBJ_WRITE(result, ptr, values[offset]);
         ARY_SET_EMBED_LEN(result, 1);
         return result;
@@ -1385,7 +1309,7 @@ ary_make_partial_step(VALUE ary, VALUE klass, long offset, long len, long step)
     }
 
     long ustep = (step < 0) ? -step : step;
-    len = (len + ustep - 1) / ustep;
+    len = roomof(len, ustep);
 
     long i;
     long j = offset + ((step > 0) ? 0 : (orig_len - 1));
@@ -1393,6 +1317,8 @@ ary_make_partial_step(VALUE ary, VALUE klass, long offset, long len, long step)
     VALUE result = ary_new(klass, len);
     if (ARY_EMBED_P(result)) {
         VALUE *ptr = (VALUE *)ARY_EMBED_PTR(result);
+        const VALUE *values = RARRAY_CONST_PTR(ary);
+
         for (i = 0; i < len; ++i) {
             RB_OBJ_WRITE(result, ptr+i, values[j]);
             j += step;
@@ -1400,7 +1326,9 @@ ary_make_partial_step(VALUE ary, VALUE klass, long offset, long len, long step)
         ARY_SET_EMBED_LEN(result, len);
     }
     else {
-        RARRAY_PTR_USE_TRANSIENT(result, ptr, {
+        const VALUE *values = RARRAY_CONST_PTR(ary);
+
+        RARRAY_PTR_USE(result, ptr, {
             for (i = 0; i < len; ++i) {
                 RB_OBJ_WRITE(result, ptr+i, values[j]);
                 j += step;
@@ -1425,20 +1353,11 @@ enum ary_take_pos_flags
 };
 
 static VALUE
-ary_take_first_or_last(int argc, const VALUE *argv, VALUE ary, enum ary_take_pos_flags last)
+ary_take_first_or_last_n(VALUE ary, long n, enum ary_take_pos_flags last)
 {
-    long n;
-    long len;
+    long len = RARRAY_LEN(ary);
     long offset = 0;
 
-    argc = rb_check_arity(argc, 0, 1);
-    /* the case optional argument is omitted should be handled in
-     * callers of this function.  if another arity case is added,
-     * this arity check needs to rewrite. */
-    RUBY_ASSERT_ALWAYS(argc == 1);
-
-    n = NUM2LONG(argv[0]);
-    len = RARRAY_LEN(ary);
     if (n > len) {
         n = len;
     }
@@ -1451,21 +1370,30 @@ ary_take_first_or_last(int argc, const VALUE *argv, VALUE ary, enum ary_take_pos
     return ary_make_partial(ary, rb_cArray, offset, n);
 }
 
+static VALUE
+ary_take_first_or_last(int argc, const VALUE *argv, VALUE ary, enum ary_take_pos_flags last)
+{
+    argc = rb_check_arity(argc, 0, 1);
+    /* the case optional argument is omitted should be handled in
+     * callers of this function.  if another arity case is added,
+     * this arity check needs to rewrite. */
+    RUBY_ASSERT_ALWAYS(argc == 1);
+    return ary_take_first_or_last_n(ary, NUM2LONG(argv[0]), last);
+}
+
 /*
  *  call-seq:
- *    array << object -> self
+ *    self << object -> self
  *
- *  Appends +object+ to +self+; returns +self+:
+ *  Appends +object+ as the last element in +self+; returns +self+:
  *
- *    a = [:foo, 'bar', 2]
- *    a << :baz # => [:foo, "bar", 2, :baz]
+ *    [:foo, 'bar', 2] << :baz # => [:foo, "bar", 2, :baz]
  *
- *  Appends +object+ as one element, even if it is another \Array:
+ *  Appends +object+ as a single element, even if it is another array:
  *
- *    a = [:foo, 'bar', 2]
- *    a1 = a << [3, 4]
- *    a1 # => [:foo, "bar", 2, [3, 4]]
+ *    [:foo, 'bar', 2] << [3, 4] # => [:foo, "bar", 2, [3, 4]]
  *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 VALUE
@@ -1473,7 +1401,7 @@ rb_ary_push(VALUE ary, VALUE item)
 {
     long idx = RARRAY_LEN((ary_verify(ary), ary));
     VALUE target_ary = ary_ensure_room_for_push(ary, 1);
-    RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+    RARRAY_PTR_USE(ary, ptr, {
         RB_OBJ_WRITE(target_ary, &ptr[idx], item);
     });
     ARY_SET_LEN(ary, idx + 1);
@@ -1493,24 +1421,20 @@ rb_ary_cat(VALUE ary, const VALUE *argv, long len)
 
 /*
  *  call-seq:
- *    array.push(*objects) -> self
- *
- *  Appends trailing elements.
+ *    push(*objects) -> self
+ *    append(*objects) -> self
  *
- *  Appends each argument in +objects+ to +self+;  returns +self+:
+ *  Appends each argument in +objects+ to +self+; returns +self+:
  *
- *    a = [:foo, 'bar', 2]
- *    a.push(:baz, :bat) # => [:foo, "bar", 2, :baz, :bat]
- *
- *  Appends each argument as one element, even if it is another \Array:
+ *    a = [:foo, 'bar', 2] # => [:foo, "bar", 2]
+ *    a.push(:baz, :bat)   # => [:foo, "bar", 2, :baz, :bat]
  *
- *    a = [:foo, 'bar', 2]
- *    a1 = a.push([:baz, :bat], [:bam, :bad])
- *    a1 # => [:foo, "bar", 2, [:baz, :bat], [:bam, :bad]]
+ *  Appends each argument as a single element, even if it is another array:
  *
- *  Array#append is an alias for Array#push.
+ *    a = [:foo, 'bar', 2]               # => [:foo, "bar", 2]
+      a.push([:baz, :bat], [:bam, :bad]) # => [:foo, "bar", 2, [:baz, :bat], [:bam, :bad]]
  *
- *  Related: #pop, #shift, #unshift.
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 static VALUE
@@ -1532,41 +1456,42 @@ rb_ary_pop(VALUE ary)
     {
         ary_resize_capa(ary, n * 2);
     }
-    --n;
-    ARY_SET_LEN(ary, n);
+
+    VALUE obj = RARRAY_AREF(ary, n - 1);
+
+    ARY_SET_LEN(ary, n - 1);
     ary_verify(ary);
-    return RARRAY_AREF(ary, n);
+    return obj;
 }
 
 /*
  *  call-seq:
- *    array.pop -> object or nil
- *    array.pop(n) -> new_array
+ *    pop -> object or nil
+ *    pop(count) -> new_array
  *
- *  Removes and returns trailing elements.
+ *  Removes and returns trailing elements of +self+.
  *
- *  When no argument is given and +self+ is not empty,
- *  removes and returns the last element:
+ *  With no argument given, removes and returns the last element, if available;
+ *  otherwise returns +nil+:
  *
  *    a = [:foo, 'bar', 2]
- *    a.pop # => 2
- *    a # => [:foo, "bar"]
+ *    a.pop  # => 2
+ *    a      # => [:foo, "bar"]
+ *    [].pop # => nil
  *
- *  Returns +nil+ if the array is empty.
+ *  With non-negative integer argument +count+ given,
+ *  returns a new array containing the trailing +count+ elements of +self+, as available:
  *
- *  When a non-negative \Integer argument +n+ is given and is in range,
- *
- *  removes and returns the last +n+ elements in a new \Array:
  *    a = [:foo, 'bar', 2]
  *    a.pop(2) # => ["bar", 2]
- *
- *  If +n+ is positive and out of range,
- *  removes and returns all elements:
+ *    a        # => [:foo]
  *
  *    a = [:foo, 'bar', 2]
  *    a.pop(50) # => [:foo, "bar", 2]
+ *    a         # => []
  *
- *  Related: #push, #shift, #unshift.
+ *  Related: Array#push;
+ *  see also {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 static VALUE
@@ -1605,35 +1530,40 @@ rb_ary_shift(VALUE ary)
 
 /*
  *  call-seq:
- *     array.shift -> object or nil
- *     array.shift(n) -> new_array
+ *    shift -> object or nil
+ *    shift(count) -> new_array or nil
  *
- *  Removes and returns leading elements.
+ *  Removes and returns leading elements from +self+.
  *
- *  When no argument is given, removes and returns the first element:
+ *  With no argument, removes and returns one element, if available,
+ *  or +nil+ otherwise:
  *
- *    a = [:foo, 'bar', 2]
- *    a.shift # => :foo
- *    a # => ['bar', 2]
- *
- *  Returns +nil+ if +self+ is empty.
- *
- *  When positive \Integer argument +n+ is given, removes the first +n+ elements;
- *  returns those elements in a new \Array:
+ *    a = [0, 1, 2, 3]
+ *    a.shift  # => 0
+ *    a        # => [1, 2, 3]
+ *    [].shift # => nil
  *
- *    a = [:foo, 'bar', 2]
- *    a.shift(2) # => [:foo, 'bar']
- *    a # => [2]
+ *  With non-negative numeric argument +count+ given,
+ *  removes and returns the first +count+ elements:
  *
- *  If +n+ is as large as or larger than <tt>self.length</tt>,
- *  removes all elements; returns those elements in a new \Array:
+ *    a = [0, 1, 2, 3]
+ *    a.shift(2)   # => [0, 1]
+ *    a            # => [2, 3]
+ *    a.shift(1.1) # => [2]
+ *    a            # => [3]
+ *    a.shift(0)   # => []
+ *    a            # => [3]
+ *
+ *  If +count+ is large,
+ *  removes and returns all elements:
  *
- *    a = [:foo, 'bar', 2]
- *    a.shift(3) # => [:foo, 'bar', 2]
+ *    a = [0, 1, 2, 3]
+ *    a.shift(50) # => [0, 1, 2, 3]
+ *    a           # => []
  *
- *  If +n+ is zero, returns a new empty \Array; +self+ is unmodified.
+ *  If +self+ is empty, returns a new empty array.
  *
- *  Related: #push, #pop, #unshift.
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 static VALUE
@@ -1654,7 +1584,7 @@ rb_ary_shift_m(int argc, VALUE *argv, VALUE ary)
     return result;
 }
 
-MJIT_FUNC_EXPORTED VALUE
+VALUE
 rb_ary_behead(VALUE ary, long n)
 {
     if (n <= 0) {
@@ -1665,7 +1595,7 @@ rb_ary_behead(VALUE ary, long n)
 
     if (!ARY_SHARED_P(ary)) {
         if (ARY_EMBED_P(ary) || RARRAY_LEN(ary) < ARY_DEFAULT_SIZE) {
-            RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+            RARRAY_PTR_USE(ary, ptr, {
                 MEMMOVE(ptr, ptr + n, VALUE, RARRAY_LEN(ary) - n);
             }); /* WB: no new reference */
             ARY_INCREASE_LEN(ary, -n);
@@ -1698,7 +1628,7 @@ make_room_for_unshift(VALUE ary, const VALUE *head, VALUE *sharedp, int argc, lo
         head = sharedp + argc + room;
     }
     ARY_SET_PTR(ary, head - argc);
-    assert(ARY_SHARED_ROOT_OCCUPIED(ARY_SHARED_ROOT(ary)));
+    RUBY_ASSERT(ARY_SHARED_ROOT_OCCUPIED(ARY_SHARED_ROOT(ary)));
 
     ary_verify(ary);
     return ARY_SHARED_ROOT(ary);
@@ -1726,12 +1656,12 @@ ary_modify_for_unshift(VALUE ary, int argc)
         capa = ARY_CAPA(ary);
         ary_make_shared(ary);
 
-        head = sharedp = RARRAY_CONST_PTR_TRANSIENT(ary);
+        head = sharedp = RARRAY_CONST_PTR(ary);
         return make_room_for_unshift(ary, head, (void *)sharedp, argc, capa, len);
     }
     else {
         /* sliding items */
-        RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+        RARRAY_PTR_USE(ary, ptr, {
             MEMMOVE(ptr + argc, ptr, VALUE, len);
         });
 
@@ -1763,8 +1693,8 @@ ary_ensure_room_for_unshift(VALUE ary, int argc)
             return ary_modify_for_unshift(ary, argc);
         }
         else {
-            const VALUE * head = RARRAY_CONST_PTR_TRANSIENT(ary);
-            void *sharedp = (void *)RARRAY_CONST_PTR_TRANSIENT(shared_root);
+            const VALUE * head = RARRAY_CONST_PTR(ary);
+            void *sharedp = (void *)RARRAY_CONST_PTR(shared_root);
 
             rb_ary_modify_check(ary);
             return make_room_for_unshift(ary, head, sharedp, argc, capa, len);
@@ -1774,19 +1704,19 @@ ary_ensure_room_for_unshift(VALUE ary, int argc)
 
 /*
  *  call-seq:
- *    array.unshift(*objects) -> self
+ *    unshift(*objects) -> self
+ *    prepend(*objects) -> self
  *
  *  Prepends the given +objects+ to +self+:
  *
  *    a = [:foo, 'bar', 2]
  *    a.unshift(:bam, :bat) # => [:bam, :bat, :foo, "bar", 2]
  *
- *  Array#prepend is an alias for Array#unshift.
- *
- *  Related: #push, #pop, #shift.
+ *  Related: Array#shift;
+ *  see also {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
-static VALUE
+VALUE
 rb_ary_unshift_m(int argc, VALUE *argv, VALUE ary)
 {
     long len = RARRAY_LEN(ary);
@@ -1806,7 +1736,7 @@ rb_ary_unshift_m(int argc, VALUE *argv, VALUE ary)
 VALUE
 rb_ary_unshift(VALUE ary, VALUE item)
 {
-    return rb_ary_unshift_m(1,&item,ary);
+    return rb_ary_unshift_m(1, &item, ary);
 }
 
 /* faster version - use this if you don't need to treat negative offset */
@@ -1859,25 +1789,38 @@ static VALUE rb_ary_aref2(VALUE ary, VALUE b, VALUE e);
 
 /*
  *  call-seq:
- *    array[index] -> object or nil
- *    array[start, length] -> object or nil
- *    array[range] -> object or nil
- *    array[aseq] -> object or nil
- *    array.slice(index) -> object or nil
- *    array.slice(start, length) -> object or nil
- *    array.slice(range) -> object or nil
- *    array.slice(aseq) -> object or nil
+ *    self[offset] -> object or nil
+ *    self[offset, size] -> object or nil
+ *    self[range] -> object or nil
+ *    self[aseq] -> object or nil
  *
  *  Returns elements from +self+; does not modify +self+.
  *
- *  When a single \Integer argument +index+ is given, returns the element at offset +index+:
+ *  In brief:
+ *
+ *    a = [:foo, 'bar', 2]
+ *
+ *    # Single argument offset: returns one element.
+ *    a[0]     # => :foo          # Zero-based index.
+ *    a[-1]    # => 2             # Negative index counts backwards from end.
+ *
+ *    # Arguments offset and size: returns an array.
+ *    a[1, 2]  # => ["bar", 2]
+ *    a[-2, 2] # => ["bar", 2]    # Negative offset counts backwards from end.
+ *
+ *    # Single argument range: returns an array.
+ *    a[0..1]  # => [:foo, "bar"]
+ *    a[0..-2] # => [:foo, "bar"] # Negative range-begin counts backwards from end.
+ *    a[-2..2] # => ["bar", 2]    # Negative range-end counts backwards from end.
+ *
+ *  When a single integer argument +offset+ is given, returns the element at offset +offset+:
  *
  *    a = [:foo, 'bar', 2]
  *    a[0] # => :foo
  *    a[2] # => 2
  *    a # => [:foo, "bar", 2]
  *
- *  If +index+ is negative, counts relative to the end of +self+:
+ *  If +offset+ is negative, counts backwards from the end of +self+:
  *
  *    a = [:foo, 'bar', 2]
  *    a[-1] # => 2
@@ -1885,35 +1828,35 @@ static VALUE rb_ary_aref2(VALUE ary, VALUE b, VALUE e);
  *
  *  If +index+ is out of range, returns +nil+.
  *
- *  When two \Integer arguments +start+ and +length+ are given,
- *  returns a new \Array of size +length+ containing successive elements beginning at offset +start+:
+ *  When two Integer arguments +offset+ and +size+ are given,
+ *  returns a new array of size +size+ containing successive elements beginning at offset +offset+:
  *
  *    a = [:foo, 'bar', 2]
  *    a[0, 2] # => [:foo, "bar"]
  *    a[1, 2] # => ["bar", 2]
  *
- *  If <tt>start + length</tt> is greater than <tt>self.length</tt>,
- *  returns all elements from offset +start+ to the end:
+ *  If <tt>offset + size</tt> is greater than <tt>self.size</tt>,
+ *  returns all elements from offset +offset+ to the end:
  *
  *    a = [:foo, 'bar', 2]
  *    a[0, 4] # => [:foo, "bar", 2]
  *    a[1, 3] # => ["bar", 2]
  *    a[2, 2] # => [2]
  *
- *  If <tt>start == self.size</tt> and <tt>length >= 0</tt>,
- *  returns a new empty \Array.
+ *  If <tt>offset == self.size</tt> and <tt>size >= 0</tt>,
+ *  returns a new empty array.
  *
- *  If +length+ is negative, returns +nil+.
+ *  If +size+ is negative, returns +nil+.
  *
- *  When a single \Range argument +range+ is given,
- *  treats <tt>range.min</tt> as +start+ above
- *  and <tt>range.size</tt> as +length+ above:
+ *  When a single Range argument +range+ is given,
+ *  treats <tt>range.min</tt> as +offset+ above
+ *  and <tt>range.size</tt> as +size+ above:
  *
  *    a = [:foo, 'bar', 2]
  *    a[0..1] # => [:foo, "bar"]
  *    a[1..2] # => ["bar", 2]
  *
- *  Special case: If <tt>range.start == a.size</tt>, returns a new empty \Array.
+ *  Special case: If <tt>range.start == a.size</tt>, returns a new empty array.
  *
  *  If <tt>range.end</tt> is negative, calculates the end index from the end:
  *
@@ -1937,7 +1880,7 @@ static VALUE rb_ary_aref2(VALUE ary, VALUE b, VALUE e);
  *    a[4..-1] # => nil
  *
  *  When a single Enumerator::ArithmeticSequence argument +aseq+ is given,
- *  returns an \Array of elements corresponding to the indexes produced by
+ *  returns an array of elements corresponding to the indexes produced by
  *  the sequence.
  *
  *    a = ['--', 'data1', '--', 'data2', '--', 'data3']
@@ -1959,7 +1902,7 @@ static VALUE rb_ary_aref2(VALUE ary, VALUE b, VALUE e);
  *    # Raises TypeError (no implicit conversion of Symbol into Integer):
  *    a[:foo]
  *
- *  Array#slice is an alias for Array#[].
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 VALUE
@@ -1983,7 +1926,7 @@ rb_ary_aref2(VALUE ary, VALUE b, VALUE e)
     return rb_ary_subseq(ary, beg, len);
 }
 
-MJIT_FUNC_EXPORTED VALUE
+VALUE
 rb_ary_aref1(VALUE ary, VALUE arg)
 {
     long beg, len, step;
@@ -2007,13 +1950,26 @@ rb_ary_aref1(VALUE ary, VALUE arg)
 
 /*
  *  call-seq:
- *    array.at(index) -> object
+ *    at(index) -> object or nil
+ *
+ *  Returns the element of +self+ specified by the given +index+
+ *  or +nil+ if there is no such element;
+ *  +index+ must be an
+ *  {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects].
+ *
+ *  For non-negative +index+, returns the element of +self+ at offset +index+:
  *
- *  Returns the element at \Integer offset +index+; does not modify +self+.
  *    a = [:foo, 'bar', 2]
- *    a.at(0) # => :foo
- *    a.at(2) # => 2
+ *    a.at(0)   # => :foo
+ *    a.at(2)   # => 2
+ *    a.at(2.0) # => 2
+ *
+ *  For negative +index+, counts backwards from the end of +self+:
+ *
+ *    a.at(-2) # => "bar"
  *
+ *  Related: Array#[];
+ *  see also {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 VALUE
@@ -2022,39 +1978,7 @@ rb_ary_at(VALUE ary, VALUE pos)
     return rb_ary_entry(ary, NUM2LONG(pos));
 }
 
-/*
- *  call-seq:
- *    array.first -> object or nil
- *    array.first(n) -> new_array
- *
- *  Returns elements from +self+; does not modify +self+.
- *
- *  When no argument is given, returns the first element:
- *
- *    a = [:foo, 'bar', 2]
- *    a.first # => :foo
- *    a # => [:foo, "bar", 2]
- *
- *  If +self+ is empty, returns +nil+.
- *
- *  When non-negative \Integer argument +n+ is given,
- *  returns the first +n+ elements in a new \Array:
- *
- *    a = [:foo, 'bar', 2]
- *    a.first(2) # => [:foo, "bar"]
- *
- *  If <tt>n >= array.size</tt>, returns all elements:
- *
- *    a = [:foo, 'bar', 2]
- *    a.first(50) # => [:foo, "bar", 2]
- *
- *  If <tt>n == 0</tt> returns an new empty \Array:
- *
- *    a = [:foo, 'bar', 2]
- *    a.first(0) # []
- *
- *  Related: #last.
- */
+#if 0
 static VALUE
 rb_ary_first(int argc, VALUE *argv, VALUE ary)
 {
@@ -2066,48 +1990,26 @@ rb_ary_first(int argc, VALUE *argv, VALUE ary)
         return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST);
     }
 }
+#endif
 
-/*
- *  call-seq:
- *    array.last  -> object or nil
- *    array.last(n) -> new_array
- *
- *  Returns elements from +self+; +self+ is not modified.
- *
- *  When no argument is given, returns the last element:
- *
- *    a = [:foo, 'bar', 2]
- *    a.last # => 2
- *    a # => [:foo, "bar", 2]
- *
- *  If +self+ is empty, returns +nil+.
- *
- *  When non-negative \Innteger argument +n+ is given,
- *  returns the last +n+ elements in a new \Array:
- *
- *    a = [:foo, 'bar', 2]
- *    a.last(2) # => ["bar", 2]
- *
- *  If <tt>n >= array.size</tt>, returns all elements:
- *
- *    a = [:foo, 'bar', 2]
- *    a.last(50) # => [:foo, "bar", 2]
- *
- *  If <tt>n == 0</tt>, returns an new empty \Array:
- *
- *    a = [:foo, 'bar', 2]
- *    a.last(0) # []
- *
- *  Related: #first.
- */
+static VALUE
+ary_first(VALUE self)
+{
+    return (RARRAY_LEN(self) == 0) ? Qnil : RARRAY_AREF(self, 0);
+}
+
+static VALUE
+ary_last(VALUE self)
+{
+    long len = RARRAY_LEN(self);
+    return (len == 0) ? Qnil : RARRAY_AREF(self, len-1);
+}
 
 VALUE
-rb_ary_last(int argc, const VALUE *argv, VALUE ary)
+rb_ary_last(int argc, const VALUE *argv, VALUE ary) // used by parse.y
 {
     if (argc == 0) {
-        long len = RARRAY_LEN(ary);
-        if (len == 0) return Qnil;
-        return RARRAY_AREF(ary, len-1);
+        return ary_last(ary);
     }
     else {
         return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_LAST);
@@ -2116,17 +2018,19 @@ rb_ary_last(int argc, const VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.fetch(index) -> element
- *    array.fetch(index, default_value) -> element
- *    array.fetch(index) {|index| ... } -> element
+ *    fetch(index) -> element
+ *    fetch(index, default_value) -> element or default_value
+ *    fetch(index) {|index| ... } -> element or block_return_value
  *
- *  Returns the element at offset  +index+.
+ *  Returns the element of +self+ at offset +index+ if +index+ is in range; +index+ must be an
+ *  {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects].
  *
- *  With the single \Integer argument +index+,
+ *  With the single argument +index+ and no block,
  *  returns the element at offset +index+:
  *
  *    a = [:foo, 'bar', 2]
- *    a.fetch(1) # => "bar"
+ *    a.fetch(1)   # => "bar"
+ *    a.fetch(1.1) # => "bar"
  *
  *  If +index+ is negative, counts from the end of the array:
  *
@@ -2134,12 +2038,12 @@ rb_ary_last(int argc, const VALUE *argv, VALUE ary)
  *    a.fetch(-1) # => 2
  *    a.fetch(-2) # => "bar"
  *
- *  With arguments +index+ and +default_value+,
- *  returns the element at offset +index+ if index is in range,
- *  otherwise returns +default_value+:
+ *  With arguments +index+ and +default_value+ (which may be any object) and no block,
+ *  returns +default_value+ if +index+ is out-of-range:
  *
  *    a = [:foo, 'bar', 2]
- *    a.fetch(1, nil) # => "bar"
+ *    a.fetch(1, nil)  # => "bar"
+ *    a.fetch(3, :foo) # => :foo
  *
  *  With argument +index+ and a block,
  *  returns the element at offset +index+ if index is in range
@@ -2149,6 +2053,7 @@ rb_ary_last(int argc, const VALUE *argv, VALUE ary)
  *    a.fetch(1) {|index| raise 'Cannot happen' } # => "bar"
  *    a.fetch(50) {|index| "Value for #{index}" } # => "Value for 50"
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -2180,14 +2085,106 @@ rb_ary_fetch(int argc, VALUE *argv, VALUE ary)
 }
 
 /*
+ * call-seq:
+ *   find(if_none_proc = nil) {|element| ... } -> object or nil
+ *   find(if_none_proc = nil) -> enumerator
+ *
+ * Returns the first element for which the block returns a truthy value.
+ *
+ * With a block given, calls the block with successive elements of the array;
+ * returns the first element for which the block returns a truthy value:
+ *
+ *   [1, 3, 5].find {|element| element > 2}                # => 3
+ *
+ * If no such element is found, calls +if_none_proc+ and returns its return value.
+ *
+ *   [1, 3, 5].find(proc {-1}) {|element| element > 12} # => -1
+ *
+ * With no block given, returns an Enumerator.
+ *
+ */
+
+static VALUE
+rb_ary_find(int argc, VALUE *argv, VALUE ary)
+{
+    VALUE if_none;
+    long idx;
+
+    RETURN_ENUMERATOR(ary, argc, argv);
+    if_none = rb_check_arity(argc, 0, 1) ? argv[0] : Qnil;
+
+    for (idx = 0; idx < RARRAY_LEN(ary); idx++) {
+        VALUE elem = RARRAY_AREF(ary, idx);
+        if (RTEST(rb_yield(elem))) {
+            return elem;
+        }
+    }
+
+    if (!NIL_P(if_none)) {
+        return rb_funcallv(if_none, idCall, 0, 0);
+    }
+    return Qnil;
+}
+
+/*
+ * call-seq:
+ *   rfind(if_none_proc = nil) {|element| ... } -> object or nil
+ *   rfind(if_none_proc = nil) -> enumerator
+ *
+ * Returns the last element for which the block returns a truthy value.
+ *
+ * With a block given, calls the block with successive elements of the array in
+ * reverse order; returns the first element for which the block returns a truthy
+ * value:
+ *
+ *   [1, 2, 3, 4, 5, 6].rfind {|element| element < 5}       # => 4
+ *
+ * If no such element is found, calls +if_none_proc+ and returns its return value.
+ *
+ *   [1, 2, 3, 4].rfind(proc {0}) {|element| element < -2}  # => 0
+ *
+ * With no block given, returns an Enumerator.
+ *
+ */
+
+static VALUE
+rb_ary_rfind(int argc, VALUE *argv, VALUE ary)
+{
+    VALUE if_none;
+    long len, idx;
+
+    RETURN_ENUMERATOR(ary, argc, argv);
+    if_none = rb_check_arity(argc, 0, 1) ? argv[0] : Qnil;
+
+    idx = RARRAY_LEN(ary);
+    while (idx--) {
+        VALUE elem = RARRAY_AREF(ary, idx);
+        if (RTEST(rb_yield(elem))) {
+            return elem;
+        }
+
+        len = RARRAY_LEN(ary);
+        idx = (idx >= len) ? len : idx;
+    }
+
+    if (!NIL_P(if_none)) {
+        return rb_funcallv(if_none, idCall, 0, 0);
+    }
+    return Qnil;
+}
+
+/*
  *  call-seq:
- *    array.index(object) -> integer or nil
- *    array.index {|element| ... } -> integer or nil
- *    array.index -> new_enumerator
+ *    find_index(object) -> integer or nil
+ *    find_index {|element| ... } -> integer or nil
+ *    find_index -> new_enumerator
+ *    index(object) -> integer or nil
+ *    index {|element| ... } -> integer or nil
+ *    index -> new_enumerator
  *
- *  Returns the index of a specified element.
+ *  Returns the zero-based integer index of a specified element, or +nil+.
  *
- *  When argument +object+ is given but no block,
+ *  With only argument +object+ given,
  *  returns the index of the first element +element+
  *  for which <tt>object == element</tt>:
  *
@@ -2196,7 +2193,7 @@ rb_ary_fetch(int argc, VALUE *argv, VALUE ary)
  *
  *  Returns +nil+ if no such element found.
  *
- *  When both argument +object+ and a block are given,
+ *  With only a block given,
  *  calls the block with each successive element;
  *  returns the index of the first element for which the block returns a truthy value:
  *
@@ -2205,16 +2202,9 @@ rb_ary_fetch(int argc, VALUE *argv, VALUE ary)
  *
  *  Returns +nil+ if the block never returns a truthy value.
  *
- *  When neither an argument nor a block is given, returns a new Enumerator:
+ *  With neither an argument nor a block given, returns a new Enumerator.
  *
- *    a = [:foo, 'bar', 2]
- *    e = a.index
- *    e # => #<Enumerator: [:foo, "bar", 2]:index>
- *    e.each {|element| element == 'bar' } # => 1
- *
- *  Array#find_index is an alias for Array#index.
- *
- *  Related: #rindex.
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -2247,20 +2237,20 @@ rb_ary_index(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.rindex(object) -> integer or nil
- *    array.rindex {|element| ... } -> integer or nil
- *    array.rindex -> new_enumerator
+ *    rindex(object) -> integer or nil
+ *    rindex {|element| ... } -> integer or nil
+ *    rindex -> new_enumerator
  *
  *  Returns the index of the last element for which <tt>object == element</tt>.
  *
- *  When argument +object+ is given but no block, returns the index of the last such element found:
+ *  With argument +object+ given, returns the index of the last such element found:
  *
  *    a = [:foo, 'bar', 2, 'bar']
  *    a.rindex('bar') # => 3
  *
  *  Returns +nil+ if no such object found.
  *
- *  When a block is given but no argument, calls the block with each successive element;
+ *  With a block given, calls the block with each successive element;
  *  returns the index of the last element for which the block returns a truthy value:
  *
  *    a = [:foo, 'bar', 2, 'bar']
@@ -2268,14 +2258,9 @@ rb_ary_index(int argc, VALUE *argv, VALUE ary)
  *
  *  Returns +nil+ if the block never returns a truthy value.
  *
- *  When neither an argument nor a block is given, returns a new \Enumerator:
+ *  When neither an argument nor a block is given, returns a new Enumerator.
  *
- *    a = [:foo, 'bar', 2, 'bar']
- *    e = a.rindex
- *    e # => #<Enumerator: [:foo, "bar", 2, "bar"]:rindex>
- *    e.each {|element| element == 'bar' } # => 3
- *
- *  Related: #index.
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -2340,7 +2325,7 @@ rb_ary_splice(VALUE ary, long beg, long len, const VALUE *rptr, long rlen)
     }
 
     {
-        const VALUE *optr = RARRAY_CONST_PTR_TRANSIENT(ary);
+        const VALUE *optr = RARRAY_CONST_PTR(ary);
         rofs = (rptr >= optr && rptr < optr + olen) ? rptr - optr : -1;
     }
 
@@ -2353,7 +2338,7 @@ rb_ary_splice(VALUE ary, long beg, long len, const VALUE *rptr, long rlen)
         len = beg + rlen;
         ary_mem_clear(ary, olen, beg - olen);
         if (rlen > 0) {
-            if (rofs != -1) rptr = RARRAY_CONST_PTR_TRANSIENT(ary) + rofs;
+            if (rofs != -1) rptr = RARRAY_CONST_PTR(ary) + rofs;
             ary_memcpy0(ary, beg, rlen, rptr, target_ary);
         }
         ARY_SET_LEN(ary, len);
@@ -2371,20 +2356,25 @@ rb_ary_splice(VALUE ary, long beg, long len, const VALUE *rptr, long rlen)
         }
 
         if (len != rlen) {
-            RARRAY_PTR_USE_TRANSIENT(ary, ptr,
+            RARRAY_PTR_USE(ary, ptr,
                                      MEMMOVE(ptr + beg + rlen, ptr + beg + len,
                                              VALUE, olen - (beg + len)));
             ARY_SET_LEN(ary, alen);
         }
         if (rlen > 0) {
-            if (rofs != -1) rptr = RARRAY_CONST_PTR_TRANSIENT(ary) + rofs;
-            /* give up wb-protected ary */
-            RB_OBJ_WB_UNPROTECT_FOR(ARRAY, ary);
+            if (rofs == -1) {
+                rb_gc_writebarrier_remember(ary);
+            }
+            else {
+                /* In this case, we're copying from a region in this array, so
+                 * we don't need to fire the write barrier. */
+                rptr = RARRAY_CONST_PTR(ary) + rofs;
+            }
 
             /* do not use RARRAY_PTR() because it can causes GC.
              * ary can contain T_NONE object because it is not cleared.
              */
-            RARRAY_PTR_USE_TRANSIENT(ary, ptr,
+            RARRAY_PTR_USE(ary, ptr,
                                      MEMMOVE(ptr + beg, rptr, VALUE, rlen));
         }
     }
@@ -2417,7 +2407,7 @@ rb_ary_resize(VALUE ary, long len)
         rb_raise(rb_eIndexError, "index %ld too big", len);
     }
     if (len > olen) {
-        if (len >= ARY_CAPA(ary)) {
+        if (len > ARY_CAPA(ary)) {
             ary_double_capa(ary, len);
         }
         ary_mem_clear(ary, olen, len - olen);
@@ -2429,9 +2419,8 @@ rb_ary_resize(VALUE ary, long len)
     else if (len <= ary_embed_capa(ary)) {
         const VALUE *ptr = ARY_HEAP_PTR(ary);
         long ptr_capa = ARY_HEAP_SIZE(ary);
-        bool is_malloc_ptr = !ARY_SHARED_P(ary) && !RARRAY_TRANSIENT_P(ary);
+        bool is_malloc_ptr = !ARY_SHARED_P(ary);
 
-        FL_UNSET(ary, RARRAY_TRANSIENT_FLAG);
         FL_SET_EMBED(ary);
 
         MEMCPY((VALUE *)ARY_EMBED_PTR(ary), ptr, VALUE, len); /* WB: no new reference */
@@ -2461,20 +2450,48 @@ static VALUE
 ary_aset_by_rb_ary_splice(VALUE ary, long beg, long len, VALUE val)
 {
     VALUE rpl = rb_ary_to_ary(val);
-    rb_ary_splice(ary, beg, len, RARRAY_CONST_PTR_TRANSIENT(rpl), RARRAY_LEN(rpl));
+    rb_ary_splice(ary, beg, len, RARRAY_CONST_PTR(rpl), RARRAY_LEN(rpl));
     RB_GC_GUARD(rpl);
     return val;
 }
 
 /*
  *  call-seq:
- *    array[index] = object -> object
- *    array[start, length] = object -> object
- *    array[range] = object -> object
- *
- *  Assigns elements in +self+; returns the given +object+.
- *
- *  When \Integer argument +index+ is given, assigns +object+ to an element in +self+.
+ *    self[index] = object -> object
+ *    self[start, length] = object -> object
+ *    self[range] = object -> object
+ *
+ *  Assigns elements in +self+, based on the given +object+; returns +object+.
+ *
+ *  In brief:
+ *
+ *      a_orig = [:foo, 'bar', 2]
+ *
+ *      # With argument index.
+ *      a = a_orig.dup
+ *      a[0] = 'foo' # => "foo"
+ *      a # => ["foo", "bar", 2]
+ *      a = a_orig.dup
+ *      a[7] = 'foo' # => "foo"
+ *      a # => [:foo, "bar", 2, nil, nil, nil, nil, "foo"]
+ *
+ *      # With arguments start and length.
+ *      a = a_orig.dup
+ *      a[0, 2] = 'foo' # => "foo"
+ *      a # => ["foo", 2]
+ *      a = a_orig.dup
+ *      a[6, 50] = 'foo' # => "foo"
+ *      a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
+ *
+ *      # With argument range.
+ *      a = a_orig.dup
+ *      a[0..1] = 'foo' # => "foo"
+ *      a # => ["foo", 2]
+ *      a = a_orig.dup
+ *      a[6..50] = 'foo' # => "foo"
+ *      a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
+ *
+ *  When Integer argument +index+ is given, assigns +object+ to an element in +self+.
  *
  *  If +index+ is non-negative, assigns +object+ the element at offset +index+:
  *
@@ -2494,7 +2511,7 @@ ary_aset_by_rb_ary_splice(VALUE ary, long beg, long len, VALUE val)
  *    a[-1] = 'two' # => "two"
  *    a # => [:foo, "bar", "two"]
  *
- *  When \Integer arguments +start+ and +length+ are given and +object+ is not an \Array,
+ *  When Integer arguments +start+ and +length+ are given and +object+ is not an array,
  *  removes <tt>length - 1</tt> elements beginning at offset +start+,
  *  and assigns +object+ at offset +start+:
  *
@@ -2529,7 +2546,7 @@ ary_aset_by_rb_ary_splice(VALUE ary, long beg, long len, VALUE val)
  *    a[1, 5] = 'foo' # => "foo"
  *    a # => [:foo, "foo"]
  *
- *  When \Range argument +range+ is given and +object+ is an \Array,
+ *  When Range argument +range+ is given and +object+ is not an array,
  *  removes <tt>length - 1</tt> elements beginning at offset +start+,
  *  and assigns +object+ at offset +start+:
  *
@@ -2544,7 +2561,8 @@ ary_aset_by_rb_ary_splice(VALUE ary, long beg, long len, VALUE val)
  *    a # => [:foo, "foo"]
  *
  *  If the array length is less than <tt>range.begin</tt>,
- *  assigns +object+ at offset <tt>range.begin</tt>, and ignores +length+:
+ *  extends the array with +nil+, assigns +object+ at offset <tt>range.begin</tt>,
+ *  and ignores +length+:
  *
  *    a = [:foo, 'bar', 2]
  *    a[6..50] = 'foo' # => "foo"
@@ -2578,6 +2596,7 @@ ary_aset_by_rb_ary_splice(VALUE ary, long beg, long len, VALUE val)
  *    a[1..5] = 'foo' # => "foo"
  *    a # => [:foo, "foo"]
  *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 static VALUE
@@ -2607,38 +2626,38 @@ rb_ary_aset(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.insert(index, *objects) -> self
+ *    insert(index, *objects) -> self
  *
- *  Inserts given +objects+ before or after the element at \Integer index +offset+;
+ *  Inserts the given +objects+ as elements of +self+;
  *  returns +self+.
  *
- *  When +index+ is non-negative, inserts all given +objects+
- *  before the element at offset +index+:
+ *  When +index+ is non-negative, inserts +objects+
+ *  _before_ the element at offset +index+:
  *
- *    a = [:foo, 'bar', 2]
- *    a.insert(1, :bat, :bam) # => [:foo, :bat, :bam, "bar", 2]
+ *    a = ['a', 'b', 'c']     # => ["a", "b", "c"]
+ *    a.insert(1, :x, :y, :z) # => ["a", :x, :y, :z, "b", "c"]
  *
  *  Extends the array if +index+ is beyond the array (<tt>index >= self.size</tt>):
  *
- *    a = [:foo, 'bar', 2]
- *    a.insert(5, :bat, :bam)
- *    a # => [:foo, "bar", 2, nil, nil, :bat, :bam]
+ *    a = ['a', 'b', 'c']     # => ["a", "b", "c"]
+ *    a.insert(5, :x, :y, :z) # => ["a", "b", "c", nil, nil, :x, :y, :z]
  *
- *  Does nothing if no objects given:
+ *  When +index+ is negative, inserts +objects+
+ *  _after_ the element at offset <tt>index + self.size</tt>:
  *
- *    a = [:foo, 'bar', 2]
- *    a.insert(1)
- *    a.insert(50)
- *    a.insert(-50)
- *    a # => [:foo, "bar", 2]
+ *    a = ['a', 'b', 'c']      # => ["a", "b", "c"]
+ *    a.insert(-2, :x, :y, :z) # => ["a", "b", :x, :y, :z, "c"]
  *
- *  When +index+ is negative, inserts all given +objects+
- *  _after_ the element at offset <tt>index+self.size</tt>:
+ *  With no +objects+ given, does nothing:
  *
- *    a = [:foo, 'bar', 2]
- *    a.insert(-2, :bat, :bam)
- *    a # => [:foo, "bar", :bat, :bam, 2]
+ *    a = ['a', 'b', 'c'] # => ["a", "b", "c"]
+ *    a.insert(1)         # => ["a", "b", "c"]
+ *    a.insert(50)        # => ["a", "b", "c"]
+ *    a.insert(-50)       # => ["a", "b", "c"]
  *
+ *  Raises IndexError if +objects+ are given and +index+ is negative and out of range.
+ *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 static VALUE
@@ -2674,14 +2693,27 @@ ary_enum_length(VALUE ary, VALUE args, VALUE eobj)
     return rb_ary_length(ary);
 }
 
+// Primitive to avoid a race condition in Array#each.
+// Return `true` and write `value` and `index` if the element exists.
+static VALUE
+ary_fetch_next(VALUE self, VALUE *index, VALUE *value)
+{
+    long i = NUM2LONG(*index);
+    if (i >= RARRAY_LEN(self)) {
+        return Qfalse;
+    }
+    *value = RARRAY_AREF(self, i);
+    *index = LONG2NUM(i + 1);
+    return Qtrue;
+}
+
 /*
  *  call-seq:
- *    array.each {|element| ... } -> self
- *    array.each -> Enumerator
- *
- *  Iterates over array elements.
+ *    each {|element| ... } -> self
+ *    each -> new_enumerator
  *
- *  When a block given, passes each successive array element to the block;
+ *  With a block given, iterates over the elements of +self+,
+ *  passing each element to the block;
  *  returns +self+:
  *
  *    a = [:foo, 'bar', 2]
@@ -2703,20 +2735,9 @@ ary_enum_length(VALUE ary, VALUE args, VALUE eobj)
  *    foo
  *    bar
  *
- *  When no block given, returns a new \Enumerator:
- *    a = [:foo, 'bar', 2]
- *
- *    e = a.each
- *    e # => #<Enumerator: [:foo, "bar", 2]:each>
- *    a1 = e.each {|element|  puts "#{element.class} #{element}" }
- *
- *  Output:
- *
- *    Symbol foo
- *    String bar
- *    Integer 2
+ *  With no block given, returns a new Enumerator.
  *
- *  Related: #each_index, #reverse_each.
+ *  Related: see {Methods for Iterating}[rdoc-ref:Array@Methods+for+Iterating].
  */
 
 VALUE
@@ -2733,12 +2754,11 @@ rb_ary_each(VALUE ary)
 
 /*
  *  call-seq:
- *    array.each_index {|index| ... } -> self
- *    array.each_index -> Enumerator
- *
- *  Iterates over array indexes.
+ *    each_index {|index| ... } -> self
+ *    each_index -> new_enumerator
  *
- *  When a block given, passes each successive array index to the block;
+ *  With a block given, iterates over the elements of +self+,
+ *  passing each <i>array index</i> to the block;
  *  returns +self+:
  *
  *    a = [:foo, 'bar', 2]
@@ -2754,26 +2774,16 @@ rb_ary_each(VALUE ary)
  *
  *    a = [:foo, 'bar', 2]
  *    a.each_index {|index| puts index; a.clear if index > 0 }
+ *    a # => []
  *
  *  Output:
  *
  *    0
  *    1
  *
- *  When no block given, returns a new \Enumerator:
- *
- *    a = [:foo, 'bar', 2]
- *    e = a.each_index
- *    e # => #<Enumerator: [:foo, "bar", 2]:each_index>
- *    a1 = e.each {|index|  puts "#{index} #{a[index]}"}
- *
- *  Output:
+ *  With no block given, returns a new Enumerator.
  *
- *    0 foo
- *    1 bar
- *    2 2
- *
- *  Related: #each, #reverse_each.
+ *  Related: see {Methods for Iterating}[rdoc-ref:Array@Methods+for+Iterating].
  */
 
 static VALUE
@@ -2790,47 +2800,26 @@ rb_ary_each_index(VALUE ary)
 
 /*
  *  call-seq:
- *    array.reverse_each {|element| ... } -> self
- *    array.reverse_each -> Enumerator
- *
- *  Iterates backwards over array elements.
+ *    reverse_each {|element| ... } -> self
+ *    reverse_each -> Enumerator
  *
- *  When a block given, passes, in reverse order, each element to the block;
+ *  When a block given, iterates backwards over the elements of +self+,
+ *  passing, in reverse order, each element to the block;
  *  returns +self+:
  *
- *    a = [:foo, 'bar', 2]
- *    a.reverse_each {|element|  puts "#{element.class} #{element}" }
- *
- *  Output:
- *
- *    Integer 2
- *    String bar
- *    Symbol foo
+ *    a = []
+ *    [0, 1, 2].reverse_each {|element| a.push(element) }
+ *    a # => [2, 1, 0]
  *
  *  Allows the array to be modified during iteration:
  *
- *    a = [:foo, 'bar', 2]
- *    a.reverse_each {|element| puts element; a.clear if element.to_s.start_with?('b') }
- *
- *  Output:
- *
- *    2
- *    bar
- *
- *  When no block given, returns a new \Enumerator:
- *
- *    a = [:foo, 'bar', 2]
- *    e = a.reverse_each
- *    e # => #<Enumerator: [:foo, "bar", 2]:reverse_each>
- *    a1 = e.each {|element|  puts "#{element.class} #{element}" }
- *
- *  Output:
+ *    a = ['a', 'b', 'c']
+ *    a.reverse_each {|element| a.clear if element.start_with?('b') }
+ *    a # => []
  *
- *    Integer 2
- *    String bar
- *    Symbol foo
+ *  When no block given, returns a new Enumerator.
  *
- *  Related: #each, #each_index.
+ *  Related: see {Methods for Iterating}[rdoc-ref:Array@Methods+for+Iterating].
  */
 
 static VALUE
@@ -2853,9 +2842,15 @@ rb_ary_reverse_each(VALUE ary)
 
 /*
  *  call-seq:
- *    array.length -> an_integer
+ *    length -> integer
+ *    size -> integer
+ *
+ *  Returns the count of elements in +self+:
+ *
+ *    [0, 1, 2].length # => 3
+ *    [].length        # => 0
  *
- *  Returns the count of elements in +self+.
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -2867,10 +2862,12 @@ rb_ary_length(VALUE ary)
 
 /*
  *  call-seq:
- *    array.empty?  -> true or false
+ *    empty?  -> true or false
  *
  *  Returns +true+ if the count of elements in +self+ is zero,
  *  +false+ otherwise.
+ *
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -2884,7 +2881,7 @@ rb_ary_dup(VALUE ary)
 {
     long len = RARRAY_LEN(ary);
     VALUE dup = rb_ary_new2(len);
-    ary_memcpy(dup, 0, len, RARRAY_CONST_PTR_TRANSIENT(ary));
+    ary_memcpy(dup, 0, len, RARRAY_CONST_PTR(ary));
     ARY_SET_LEN(dup, len);
 
     ary_verify(ary);
@@ -3005,23 +3002,28 @@ rb_ary_join(VALUE ary, VALUE sep)
         StringValue(sep);
         len += RSTRING_LEN(sep) * (RARRAY_LEN(ary) - 1);
     }
-    for (i=0; i<RARRAY_LEN(ary); i++) {
+    long len_memo = RARRAY_LEN(ary);
+    for (i=0; i < len_memo; i++) {
         val = RARRAY_AREF(ary, i);
-        tmp = rb_check_string_type(val);
-
-        if (NIL_P(tmp) || tmp != val) {
-            int first;
-            long n = RARRAY_LEN(ary);
-            if (i > n) i = n;
-            result = rb_str_buf_new(len + (n-i)*10);
-            rb_enc_associate(result, rb_usascii_encoding());
-            i = ary_join_0(ary, sep, i, result);
-            first = i == 0;
-            ary_join_1(ary, ary, sep, i, result, &first);
-            return result;
+        if (RB_UNLIKELY(!RB_TYPE_P(val, T_STRING))) {
+            tmp = rb_check_string_type(val);
+            if (NIL_P(tmp) || tmp != val) {
+                int first;
+                long n = RARRAY_LEN(ary);
+                if (i > n) i = n;
+                result = rb_str_buf_new(len + (n-i)*10);
+                rb_enc_associate(result, rb_usascii_encoding());
+                i = ary_join_0(ary, sep, i, result);
+                first = i == 0;
+                ary_join_1(ary, ary, sep, i, result, &first);
+                return result;
+            }
+            len += RSTRING_LEN(tmp);
+            len_memo = RARRAY_LEN(ary);
+        }
+        else {
+            len += RSTRING_LEN(val);
         }
-
-        len += RSTRING_LEN(tmp);
     }
 
     result = rb_str_new(0, len);
@@ -3034,31 +3036,32 @@ rb_ary_join(VALUE ary, VALUE sep)
 
 /*
  *  call-seq:
- *    array.join ->new_string
- *    array.join(separator = $,) -> new_string
+ *    join(separator = $,) -> new_string
  *
- *  Returns the new \String formed by joining the array elements after conversion.
- *  For each element +element+:
+ *  Returns the new string formed by joining the converted elements of +self+;
+ *  for each element +element+:
  *
- *  - Uses <tt>element.to_s</tt> if +element+ is not a <tt>kind_of?(Array)</tt>.
- *  - Uses recursive <tt>element.join(separator)</tt> if +element+ is a <tt>kind_of?(Array)</tt>.
+ *  - Converts recursively using <tt>element.join(separator)</tt>
+ *    if +element+ is a <tt>kind_of?(Array)</tt>.
+ *  - Otherwise, converts using <tt>element.to_s</tt>.
  *
- *  With no argument, joins using the output field separator, <tt>$,</tt>:
+ *  With no argument given, joins using the output field separator, <tt>$,</tt>:
  *
  *    a = [:foo, 'bar', 2]
  *    $, # => nil
  *    a.join # => "foobar2"
  *
- *  With \string argument +separator+, joins using that separator:
+ *  With string argument +separator+ given, joins using that separator:
  *
  *    a = [:foo, 'bar', 2]
  *    a.join("\n") # => "foo\nbar\n2"
  *
- *  Joins recursively for nested Arrays:
+ *  Joins recursively for nested arrays:
  *
  *   a = [:foo, [:bar, [:baz, :bat]]]
  *   a.join # => "foobarbazbat"
  *
+ *  Related: see {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].
  */
 static VALUE
 rb_ary_join_m(int argc, VALUE *argv, VALUE ary)
@@ -3095,15 +3098,16 @@ inspect_ary(VALUE ary, VALUE dummy, int recur)
 
 /*
  *  call-seq:
- *    array.inspect -> new_string
+ *    inspect -> new_string
+ *    to_s -> new_string
  *
- *  Returns the new \String formed by calling method <tt>#inspect</tt>
+ *  Returns the new string formed by calling method <tt>#inspect</tt>
  *  on each array element:
  *
  *    a = [:foo, 'bar', 2]
  *    a.inspect # => "[:foo, \"bar\", 2]"
  *
- *  Array#to_s is an alias for Array#inspect.
+ *  Related: see {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].
  */
 
 static VALUE
@@ -3123,21 +3127,17 @@ rb_ary_to_s(VALUE ary)
  *  call-seq:
  *    to_a -> self or new_array
  *
- *  When +self+ is an instance of \Array, returns +self+:
- *
- *    a = [:foo, 'bar', 2]
- *    a.to_a # => [:foo, "bar", 2]
+ *  When +self+ is an instance of \Array, returns +self+.
  *
- *  Otherwise, returns a new \Array containing the elements of +self+:
+ *  Otherwise, returns a new array containing the elements of +self+:
  *
  *    class MyArray < Array; end
- *    a = MyArray.new(['foo', 'bar', 'two'])
- *    a.instance_of?(Array) # => false
- *    a.kind_of?(Array) # => true
- *    a1 = a.to_a
- *    a1 # => ["foo", "bar", "two"]
- *    a1.class # => Array # Not MyArray
+ *    my_a = MyArray.new(['foo', 'bar', 'two'])
+ *    a = my_a.to_a
+ *    a # => ["foo", "bar", "two"]
+ *    a.class # => Array # Not MyArray.
  *
+ *  Related: see {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].
  */
 
 static VALUE
@@ -3153,27 +3153,27 @@ rb_ary_to_a(VALUE ary)
 
 /*
  *  call-seq:
- *    array.to_h -> new_hash
- *    array.to_h {|item| ... } -> new_hash
+ *    to_h -> new_hash
+ *    to_h {|element| ... } -> new_hash
  *
- *  Returns a new \Hash formed from +self+.
+ *  Returns a new hash formed from +self+.
  *
- *  When a block is given, calls the block with each array element;
- *  the block must return a 2-element \Array whose two elements
- *  form a key-value pair in the returned \Hash:
+ *  With no block given, each element of +self+ must be a 2-element sub-array;
+ *  forms each sub-array into a key-value pair in the new hash:
  *
- *    a = ['foo', :bar, 1, [2, 3], {baz: 4}]
- *    h = a.to_h {|item| [item, item] }
- *    h # => {"foo"=>"foo", :bar=>:bar, 1=>1, [2, 3]=>[2, 3], {:baz=>4}=>{:baz=>4}}
+ *    a = [['foo', 'zero'], ['bar', 'one'], ['baz', 'two']]
+ *    a.to_h # => {"foo"=>"zero", "bar"=>"one", "baz"=>"two"}
+ *    [].to_h # => {}
  *
- *  When no block is given, +self+ must be an \Array of 2-element sub-arrays,
- *  each sub-array is formed into a key-value pair in the new \Hash:
+ *  With a block given, the block must return a 2-element array;
+ *  calls the block with each element of +self+;
+ *  forms each returned array into a key-value pair in the returned hash:
  *
- *    [].to_h # => {}
- *    a = [['foo', 'zero'], ['bar', 'one'], ['baz', 'two']]
- *    h = a.to_h
- *    h # => {"foo"=>"zero", "bar"=>"one", "baz"=>"two"}
+ *    a = ['foo', :bar, 1, [2, 3], {baz: 4}]
+ *    a.to_h {|element| [element, element.class] }
+ *    # => {"foo"=>String, :bar=>Symbol, 1=>Integer, [2, 3]=>Array, {:baz=>4}=>Hash}
  *
+ *  Related: see {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].
  */
 
 static VALUE
@@ -3202,7 +3202,7 @@ rb_ary_to_h(VALUE ary)
 
 /*
  *  call-seq:
- *    array.to_ary -> self
+ *    to_ary -> self
  *
  *  Returns +self+.
  */
@@ -3231,7 +3231,7 @@ rb_ary_reverse(VALUE ary)
 
     rb_ary_modify(ary);
     if (len > 1) {
-        RARRAY_PTR_USE_TRANSIENT(ary, p1, {
+        RARRAY_PTR_USE(ary, p1, {
             p2 = p1 + len - 1;	/* points last item */
             ary_reverse(p1, p2);
         }); /* WB: no new reference */
@@ -3241,13 +3241,16 @@ rb_ary_reverse(VALUE ary)
 
 /*
  *  call-seq:
- *    array.reverse! -> self
+ *    reverse! -> self
  *
- *  Reverses +self+ in place:
+ *  Reverses the order of the elements of +self+;
+ *  returns +self+:
  *
- *    a = ['foo', 'bar', 'two']
- *    a.reverse! # => ["two", "bar", "foo"]
+ *    a = [0, 1, 2]
+ *    a.reverse! # => [2, 1, 0]
+ *    a          # => [2, 1, 0]
  *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 static VALUE
@@ -3258,14 +3261,13 @@ rb_ary_reverse_bang(VALUE ary)
 
 /*
  *  call-seq:
- *    array.reverse -> new_array
+ *    reverse -> new_array
  *
- *  Returns a new \Array with the elements of +self+ in reverse order:
+ *  Returns a new array containing the elements of +self+ in reverse order:
  *
- *    a = ['foo', 'bar', 'two']
- *    a1 = a.reverse
- *    a1 # => ["two", "bar", "foo"]
+ *    [0, 1, 2].reverse # => [2, 1, 0]
  *
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
 static VALUE
@@ -3275,8 +3277,8 @@ rb_ary_reverse_m(VALUE ary)
     VALUE dup = rb_ary_new2(len);
 
     if (len > 0) {
-        const VALUE *p1 = RARRAY_CONST_PTR_TRANSIENT(ary);
-        VALUE *p2 = (VALUE *)RARRAY_CONST_PTR_TRANSIENT(dup) + len - 1;
+        const VALUE *p1 = RARRAY_CONST_PTR(ary);
+        VALUE *p2 = (VALUE *)RARRAY_CONST_PTR(dup) + len - 1;
         do *p2-- = *p1++; while (--len > 0);
     }
     ARY_SET_LEN(dup, RARRAY_LEN(ary));
@@ -3318,7 +3320,7 @@ rb_ary_rotate(VALUE ary, long cnt)
     if (cnt != 0) {
         long len = RARRAY_LEN(ary);
         if (len > 1 && (cnt = rotate_count(cnt, len)) > 0) {
-            RARRAY_PTR_USE_TRANSIENT(ary, ptr, ary_rotate_ptr(ptr, len, cnt));
+            RARRAY_PTR_USE(ary, ptr, ary_rotate_ptr(ptr, len, cnt));
             return ary;
         }
     }
@@ -3327,48 +3329,34 @@ rb_ary_rotate(VALUE ary, long cnt)
 
 /*
  *  call-seq:
- *    array.rotate! -> self
- *    array.rotate!(count) -> self
+ *    rotate!(count = 1) -> self
  *
  *  Rotates +self+ in place by moving elements from one end to the other; returns +self+.
  *
- *  When no argument given, rotates the first element to the last position:
- *
- *    a = [:foo, 'bar', 2, 'bar']
- *    a.rotate! # => ["bar", 2, "bar", :foo]
- *
- *  When given a non-negative \Integer +count+,
+ *  With non-negative numeric +count+,
  *  rotates +count+ elements from the beginning to the end:
  *
- *    a = [:foo, 'bar', 2]
- *    a.rotate!(2)
- *    a # => [2, :foo, "bar"]
+ *    [0, 1, 2, 3].rotate!(2)   # => [2, 3, 0, 1]
+      [0, 1, 2, 3].rotate!(2.1) # => [2, 3, 0, 1]
  *
  *  If +count+ is large, uses <tt>count % array.size</tt> as the count:
  *
- *    a = [:foo, 'bar', 2]
- *    a.rotate!(20)
- *    a # => [2, :foo, "bar"]
+ *    [0, 1, 2, 3].rotate!(21) # => [1, 2, 3, 0]
  *
- *  If +count+ is zero, returns +self+ unmodified:
+ *  If +count+ is zero, rotates no elements:
  *
- *    a = [:foo, 'bar', 2]
- *    a.rotate!(0)
- *    a # => [:foo, "bar", 2]
+ *    [0, 1, 2, 3].rotate!(0) # => [0, 1, 2, 3]
  *
- *  When given a negative Integer +count+, rotates in the opposite direction,
+ *  With a negative numeric +count+, rotates in the opposite direction,
  *  from end to beginning:
  *
- *    a = [:foo, 'bar', 2]
- *    a.rotate!(-2)
- *    a # => ["bar", 2, :foo]
+ *    [0, 1, 2, 3].rotate!(-1) # => [3, 0, 1, 2]
  *
  *  If +count+ is small (far from zero), uses <tt>count % array.size</tt> as the count:
  *
- *    a = [:foo, 'bar', 2]
- *    a.rotate!(-5)
- *    a # => ["bar", 2, :foo]
+ *    [0, 1, 2, 3].rotate!(-21) # => [3, 0, 1, 2]
  *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 static VALUE
@@ -3381,51 +3369,35 @@ rb_ary_rotate_bang(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.rotate -> new_array
- *    array.rotate(count) -> new_array
+ *    rotate(count = 1) -> new_array
  *
- *  Returns a new \Array formed from +self+ with elements
+ *  Returns a new array formed from +self+ with elements
  *  rotated from one end to the other.
  *
- *  When no argument given, returns a new \Array that is like +self+,
- *  except that the first element has been rotated to the last position:
- *
- *    a = [:foo, 'bar', 2, 'bar']
- *    a1 = a.rotate
- *    a1 # => ["bar", 2, "bar", :foo]
+ *  With non-negative numeric +count+,
+ *  rotates elements from the beginning to the end:
  *
- *  When given a non-negative \Integer +count+,
- *  returns a new \Array with +count+ elements rotated from the beginning to the end:
- *
- *    a = [:foo, 'bar', 2]
- *    a1 = a.rotate(2)
- *    a1 # => [2, :foo, "bar"]
+ *    [0, 1, 2, 3].rotate(2)   # => [2, 3, 0, 1]
+ *    [0, 1, 2, 3].rotate(2.1) # => [2, 3, 0, 1]
  *
  *  If +count+ is large, uses <tt>count % array.size</tt> as the count:
  *
- *    a = [:foo, 'bar', 2]
- *    a1 = a.rotate(20)
- *    a1 # => [2, :foo, "bar"]
+ *    [0, 1, 2, 3].rotate(22) # => [2, 3, 0, 1]
  *
- *  If +count+ is zero, returns a copy of +self+, unmodified:
+ *  With a +count+ of zero, rotates no elements:
  *
- *    a = [:foo, 'bar', 2]
- *    a1 = a.rotate(0)
- *    a1 # => [:foo, "bar", 2]
+ *    [0, 1, 2, 3].rotate(0) # => [0, 1, 2, 3]
  *
- *  When given a negative \Integer +count+, rotates in the opposite direction,
- *  from end to beginning:
+ *  With negative numeric +count+, rotates in the opposite direction,
+ *  from the end to the beginning:
  *
- *    a = [:foo, 'bar', 2]
- *    a1 = a.rotate(-2)
- *    a1 # => ["bar", 2, :foo]
+ *    [0, 1, 2, 3].rotate(-1) # => [3, 0, 1, 2]
  *
  *  If +count+ is small (far from zero), uses <tt>count % array.size</tt> as the count:
  *
- *    a = [:foo, 'bar', 2]
- *    a1 = a.rotate(-5)
- *    a1 # => ["bar", 2, :foo]
+ *    [0, 1, 2, 3].rotate(-21) # => [3, 0, 1, 2]
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -3440,7 +3412,7 @@ rb_ary_rotate_m(int argc, VALUE *argv, VALUE ary)
     rotated = rb_ary_new2(len);
     if (len > 0) {
         cnt = rotate_count(cnt, len);
-        ptr = RARRAY_CONST_PTR_TRANSIENT(ary);
+        ptr = RARRAY_CONST_PTR(ary);
         len -= cnt;
         ary_memcpy(rotated, 0, len, ptr + cnt);
         ary_memcpy(rotated, len, cnt, ptr);
@@ -3452,7 +3424,6 @@ rb_ary_rotate_m(int argc, VALUE *argv, VALUE ary)
 struct ary_sort_data {
     VALUE ary;
     VALUE receiver;
-    struct cmp_opt_data cmp_opt;
 };
 
 static VALUE
@@ -3498,15 +3469,15 @@ sort_2(const void *ap, const void *bp, void *dummy)
     VALUE a = *(const VALUE *)ap, b = *(const VALUE *)bp;
     int n;
 
-    if (FIXNUM_P(a) && FIXNUM_P(b) && CMP_OPTIMIZABLE(data->cmp_opt, Integer)) {
+    if (FIXNUM_P(a) && FIXNUM_P(b) && CMP_OPTIMIZABLE(INTEGER)) {
         if ((long)a > (long)b) return 1;
         if ((long)a < (long)b) return -1;
         return 0;
     }
-    if (STRING_P(a) && STRING_P(b) && CMP_OPTIMIZABLE(data->cmp_opt, String)) {
+    if (STRING_P(a) && STRING_P(b) && CMP_OPTIMIZABLE(STRING)) {
         return rb_str_cmp(a, b);
     }
-    if (RB_FLOAT_TYPE_P(a) && CMP_OPTIMIZABLE(data->cmp_opt, Float)) {
+    if (RB_FLOAT_TYPE_P(a) && CMP_OPTIMIZABLE(FLOAT)) {
         return rb_float_cmp(a, b);
     }
 
@@ -3519,50 +3490,19 @@ sort_2(const void *ap, const void *bp, void *dummy)
 
 /*
  *  call-seq:
- *    array.sort! -> self
- *    array.sort! {|a, b| ... } -> self
- *
- *  Returns +self+ with its elements sorted in place.
- *
- *  With no block, compares elements using operator <tt><=></tt>
- *  (see Comparable):
- *
- *    a = 'abcde'.split('').shuffle
- *    a # => ["e", "b", "d", "a", "c"]
- *    a.sort!
- *    a # => ["a", "b", "c", "d", "e"]
- *
- *  With a block, calls the block with each element pair;
- *  for each element pair +a+ and +b+, the block should return an integer:
- *
- *  - Negative when +b+ is to follow +a+.
- *  - Zero when +a+ and +b+ are equivalent.
- *  - Positive when +a+ is to follow +b+.
- *
- *  Example:
- *
- *    a = 'abcde'.split('').shuffle
- *    a # => ["e", "b", "d", "a", "c"]
- *    a.sort! {|a, b| a <=> b }
- *    a # => ["a", "b", "c", "d", "e"]
- *    a.sort! {|a, b| b <=> a }
- *    a # => ["e", "d", "c", "b", "a"]
+ *    sort! -> self
+ *    sort! {|a, b| ... } -> self
  *
- *  When the block returns zero, the order for +a+ and +b+ is indeterminate,
- *  and may be unstable:
- *
- *    a = 'abcde'.split('').shuffle
- *    a # => ["e", "b", "d", "a", "c"]
- *    a.sort! {|a, b| 0 }
- *    a # => ["d", "e", "c", "a", "b"]
+ *  Like Array#sort, but returns +self+ with its elements sorted in place.
  *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 VALUE
 rb_ary_sort_bang(VALUE ary)
 {
     rb_ary_modify(ary);
-    assert(!ARY_SHARED_P(ary));
+    RUBY_ASSERT(!ARY_SHARED_P(ary));
     if (RARRAY_LEN(ary) > 1) {
         VALUE tmp = ary_make_substitution(ary); /* only ary refers tmp */
         struct ary_sort_data data;
@@ -3570,8 +3510,6 @@ rb_ary_sort_bang(VALUE ary)
         RBASIC_CLEAR_CLASS(tmp);
         data.ary = tmp;
         data.receiver = ary;
-        data.cmp_opt.opt_methods = 0;
-        data.cmp_opt.opt_inited = 0;
         RARRAY_PTR_USE(tmp, ptr, {
             ruby_qsort(ptr, len, sizeof(VALUE),
                        rb_block_given_p()?sort_1:sort_2, &data);
@@ -3582,6 +3520,9 @@ rb_ary_sort_bang(VALUE ary)
                 rb_ary_unshare(ary);
                 FL_SET_EMBED(ary);
             }
+            if (ARY_EMBED_LEN(tmp) > ARY_CAPA(ary)) {
+                ary_resize_capa(ary, ARY_EMBED_LEN(tmp));
+            }
             ary_memcpy(ary, 0, ARY_EMBED_LEN(tmp), ARY_EMBED_PTR(tmp));
             ARY_SET_LEN(ary, ARY_EMBED_LEN(tmp));
         }
@@ -3591,7 +3532,7 @@ rb_ary_sort_bang(VALUE ary)
                 ARY_SET_CAPA(ary, RARRAY_LEN(tmp));
             }
             else {
-                assert(!ARY_SHARED_P(tmp));
+                RUBY_ASSERT(!ARY_SHARED_P(tmp));
                 if (ARY_EMBED_P(ary)) {
                     FL_UNSET_EMBED(ary);
                 }
@@ -3607,10 +3548,9 @@ rb_ary_sort_bang(VALUE ary)
                 ARY_SET_CAPA(ary, ARY_HEAP_LEN(tmp));
             }
             /* tmp was lost ownership for the ptr */
-            FL_UNSET(tmp, FL_FREEZE);
             FL_SET_EMBED(tmp);
             ARY_SET_EMBED_LEN(tmp, 0);
-            FL_SET(tmp, FL_FREEZE);
+            OBJ_FREEZE(tmp);
         }
         /* tmp will be GC'ed. */
         RBASIC_SET_CLASS_RAW(tmp, rb_cArray); /* rb_cArray must be marked */
@@ -3621,21 +3561,18 @@ rb_ary_sort_bang(VALUE ary)
 
 /*
  *  call-seq:
- *    array.sort -> new_array
- *    array.sort {|a, b| ... } -> new_array
+ *    sort -> new_array
+ *    sort {|a, b| ... } -> new_array
  *
- *  Returns a new \Array whose elements are those from +self+, sorted.
+ *  Returns a new array containing the elements of +self+, sorted.
  *
- *  With no block, compares elements using operator <tt><=></tt>
- *  (see Comparable):
+ *  With no block given, compares elements using operator <tt>#<=></tt>
+ *  (see Object#<=>):
  *
- *    a = 'abcde'.split('').shuffle
- *    a # => ["e", "b", "d", "a", "c"]
- *    a1 = a.sort
- *    a1 # => ["a", "b", "c", "d", "e"]
+ *    [0, 2, 3, 1].sort # => [0, 1, 2, 3]
  *
- *  With a block, calls the block with each element pair;
- *  for each element pair +a+ and +b+, the block should return an integer:
+ *  With a block given, calls the block with each combination of pairs of elements from +self+;
+ *  for each pair +a+ and +b+, the block should return a numeric:
  *
  *  - Negative when +b+ is to follow +a+.
  *  - Zero when +a+ and +b+ are equivalent.
@@ -3643,22 +3580,17 @@ rb_ary_sort_bang(VALUE ary)
  *
  *  Example:
  *
- *    a = 'abcde'.split('').shuffle
- *    a # => ["e", "b", "d", "a", "c"]
- *    a1 = a.sort {|a, b| a <=> b }
- *    a1 # => ["a", "b", "c", "d", "e"]
- *    a2 = a.sort {|a, b| b <=> a }
- *    a2 # => ["e", "d", "c", "b", "a"]
+ *    a = [3, 2, 0, 1]
+ *    a.sort {|a, b| a <=> b } # => [0, 1, 2, 3]
+ *    a.sort {|a, b| b <=> a } # => [3, 2, 1, 0]
  *
  *  When the block returns zero, the order for +a+ and +b+ is indeterminate,
- *  and may be unstable:
+ *  and may be unstable.
  *
- *    a = 'abcde'.split('').shuffle
- *    a # => ["e", "b", "d", "a", "c"]
- *    a1 = a.sort {|a, b| 0 }
- *    a1 # =>  ["c", "e", "b", "d", "a"]
+ *  See an example in Numeric#nonzero? for the idiom to sort more
+ *  complex structure.
  *
- *  Related: Enumerable#sort_by.
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 VALUE
@@ -3673,12 +3605,15 @@ static VALUE rb_ary_bsearch_index(VALUE ary);
 
 /*
  *  call-seq:
- *    array.bsearch {|element| ... } -> object
- *    array.bsearch -> new_enumerator
+ *    bsearch {|element| ... } -> found_element or nil
+ *    bsearch -> new_enumerator
+ *
+ *  Returns the element from +self+ found by a binary search,
+ *  or +nil+ if the search found no suitable element.
  *
- *  Returns an element from +self+ selected by a binary search.
+ *  See {Binary Searching}[rdoc-ref:language/bsearch.rdoc].
  *
- *  See {Binary Searching}[rdoc-ref:bsearch.rdoc].
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -3694,11 +3629,15 @@ rb_ary_bsearch(VALUE ary)
 
 /*
  *  call-seq:
- *    array.bsearch_index {|element| ... } -> integer or nil
- *    array.bsearch_index -> new_enumerator
+ *    bsearch_index {|element| ... } -> integer or nil
+ *    bsearch_index -> new_enumerator
  *
- *  Searches +self+ as described at method #bsearch,
- *  but returns the _index_ of the found element instead of the element itself.
+ *  Returns the integer index of the element from +self+ found by a binary search,
+ *  or +nil+ if the search found no suitable element.
+ *
+ *  See {Binary Searching}[rdoc-ref:language/bsearch.rdoc].
+ *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -3728,8 +3667,8 @@ rb_ary_bsearch_index(VALUE ary)
             const VALUE zero = INT2FIX(0);
             switch (rb_cmpint(rb_funcallv(v, id_cmp, 1, &zero), v, zero)) {
               case 0: return INT2FIX(mid);
-              case 1: smaller = 1; break;
-              case -1: smaller = 0;
+              case 1: smaller = 0; break;
+              case -1: smaller = 1;
             }
         }
         else {
@@ -3757,28 +3696,24 @@ sort_by_i(RB_BLOCK_CALL_FUNC_ARGLIST(i, dummy))
 
 /*
  *  call-seq:
- *    array.sort_by! {|element| ... } -> self
- *    array.sort_by! -> new_enumerator
+ *    sort_by! {|element| ... } -> self
+ *    sort_by! -> new_enumerator
  *
- *  Sorts the elements of +self+ in place,
- *  using an ordering determined by the block; returns self.
+ *  With a block given, sorts the elements of +self+ in place;
+ *  returns self.
  *
  *  Calls the block with each successive element;
- *  sorts elements based on the values returned from the block.
- *
- *  For duplicates returned by the block, the ordering is indeterminate, and may be unstable.
- *
- *  This example sorts strings based on their sizes:
+ *  sorts elements based on the values returned from the block:
  *
  *    a = ['aaaa', 'bbb', 'cc', 'd']
  *    a.sort_by! {|element| element.size }
  *    a # => ["d", "cc", "bbb", "aaaa"]
  *
- *  Returns a new \Enumerator if no block given:
+ *  For duplicate values returned by the block, the ordering is indeterminate, and may be unstable.
  *
- *    a = ['aaaa', 'bbb', 'cc', 'd']
- *    a.sort_by! # => #<Enumerator: ["aaaa", "bbb", "cc", "d"]:sort_by!>
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 static VALUE
@@ -3788,30 +3723,32 @@ rb_ary_sort_by_bang(VALUE ary)
 
     RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
     rb_ary_modify(ary);
-    sorted = rb_block_call(ary, rb_intern("sort_by"), 0, 0, sort_by_i, 0);
-    rb_ary_replace(ary, sorted);
+    if (RARRAY_LEN(ary) > 1) {
+        sorted = rb_block_call(ary, rb_intern("sort_by"), 0, 0, sort_by_i, 0);
+        rb_ary_replace(ary, sorted);
+    }
     return ary;
 }
 
 
 /*
  *  call-seq:
- *    array.map {|element| ... } -> new_array
- *    array.map -> new_enumerator
+ *    collect {|element| ... } -> new_array
+ *    collect -> new_enumerator
+ *    map {|element| ... } -> new_array
+ *    map -> new_enumerator
  *
- *  Calls the block, if given, with each element of +self+;
- *  returns a new \Array whose elements are the return values from the block:
+ *  With a block given, calls the block with each element of +self+;
+ *  returns a new array whose elements are the return values from the block:
  *
  *    a = [:foo, 'bar', 2]
  *    a1 = a.map {|element| element.class }
  *    a1 # => [Symbol, String, Integer]
  *
- *  Returns a new \Enumerator if no block given:
- *    a = [:foo, 'bar', 2]
- *    a1 = a.map
- *    a1 # => #<Enumerator: [:foo, "bar", 2]:map>
+ *  With no block given, returns a new Enumerator.
  *
- *  Array#collect is an alias for Array#map.
+ *  Related: #collect!;
+ *  see also {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].
  */
 
 static VALUE
@@ -3831,22 +3768,22 @@ rb_ary_collect(VALUE ary)
 
 /*
  *  call-seq:
- *    array.map! {|element| ... } -> self
- *    array.map! -> new_enumerator
+ *    collect! {|element| ... } -> self
+ *    collect! -> new_enumerator
+ *    map! {|element| ... } -> self
+ *    map! -> new_enumerator
  *
- *  Calls the block, if given, with each element;
- *  replaces the element with the block's return value:
+ *  With a block given, calls the block with each element of +self+
+ *  and replaces the element with the block's return value;
+ *  returns +self+:
  *
  *    a = [:foo, 'bar', 2]
  *    a.map! { |element| element.class } # => [Symbol, String, Integer]
  *
- *  Returns a new \Enumerator if no block given:
+ *  With no block given, returns a new Enumerator.
  *
- *    a = [:foo, 'bar', 2]
- *    a1 = a.map!
- *    a1 # => #<Enumerator: [:foo, "bar", 2]:map!>
- *
- *  Array#collect! is an alias for Array#map!.
+ *  Related: #collect;
+ *  see also {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].
  */
 
 static VALUE
@@ -3898,7 +3835,7 @@ append_values_at_single(VALUE result, VALUE ary, long olen, VALUE idx)
     /* check if idx is Range */
     else if (rb_range_beg_len(idx, &beg, &len, olen, 1)) {
         if (len > 0) {
-            const VALUE *const src = RARRAY_CONST_PTR_TRANSIENT(ary);
+            const VALUE *const src = RARRAY_CONST_PTR(ary);
             const long end = beg + len;
             const long prevlen = RARRAY_LEN(result);
             if (beg < olen) {
@@ -3918,45 +3855,108 @@ append_values_at_single(VALUE result, VALUE ary, long olen, VALUE idx)
 
 /*
  *  call-seq:
- *    array.values_at(*indexes) -> new_array
+ *    values_at(*specifiers) -> new_array
  *
- *  Returns a new \Array whose elements are the elements
- *  of +self+ at the given \Integer or \Range +indexes+.
+ *  Returns elements from +self+ in a new array; does not modify +self+.
  *
- *  For each positive +index+, returns the element at offset +index+:
+ *  The objects included in the returned array are the elements of +self+
+ *  selected by the given +specifiers+,
+ *  each of which must be a numeric index or a Range.
  *
- *    a = [:foo, 'bar', 2]
- *    a.values_at(0, 2) # => [:foo, 2]
- *    a.values_at(0..1) # => [:foo, "bar"]
+ *  In brief:
  *
- *  The given +indexes+ may be in any order, and may repeat:
+ *    a = ['a', 'b', 'c', 'd']
  *
- *    a = [:foo, 'bar', 2]
- *    a.values_at(2, 0, 1, 0, 2) # => [2, :foo, "bar", :foo, 2]
- *    a.values_at(1, 0..2) # => ["bar", :foo, "bar", 2]
+ *    # Index specifiers.
+ *    a.values_at(2, 0, 2, 0)     # => ["c", "a", "c", "a"] # May repeat.
+ *    a.values_at(-4, -3, -2, -1) # => ["a", "b", "c", "d"] # Counts backwards if negative.
+ *    a.values_at(-50, 50)        # => [nil, nil]           # Outside of self.
  *
- *  Assigns +nil+ for an +index+ that is too large:
+ *    # Range specifiers.
+ *    a.values_at(1..3)       # => ["b", "c", "d"] # From range.begin to range.end.
+ *    a.values_at(1...3)      # => ["b", "c"]      # End excluded.
+ *    a.values_at(3..1)       # => []              # No such elements.
  *
- *    a = [:foo, 'bar', 2]
- *    a.values_at(0, 3, 1, 3) # => [:foo, nil, "bar", nil]
+ *    a.values_at(-3..3)  # => ["b", "c", "d"]     # Negative range.begin counts backwards.
+ *    a.values_at(-50..3)                          # Raises RangeError.
  *
- *  Returns a new empty \Array if no arguments given.
+ *    a.values_at(1..-2)  # => ["b", "c"]          # Negative range.end counts backwards.
+ *    a.values_at(1..-50) # => []                  # No such elements.
  *
- *  For each negative +index+, counts backward from the end of the array:
+ *    # Mixture of specifiers.
+ *    a.values_at(2..3, 3, 0..1, 0) # => ["c", "d", "d", "a", "b", "a"]
  *
- *    a = [:foo, 'bar', 2]
- *    a.values_at(-1, -3) # => [2, :foo]
+ *  With no +specifiers+ given, returns a new empty array:
  *
- *  Assigns +nil+ for an +index+ that is too small:
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.values_at # => []
  *
- *    a = [:foo, 'bar', 2]
- *    a.values_at(0, -5, 1, -6, 2) # => [:foo, nil, "bar", nil, 2]
+ *  For each numeric specifier +index+, includes an element:
  *
- *  The given +indexes+ may have a mixture of signs:
+ *  - For each non-negative numeric specifier +index+ that is in-range (less than <tt>self.size</tt>),
+ *    includes the element at offset +index+:
  *
- *    a = [:foo, 'bar', 2]
- *    a.values_at(0, -2, 1, -1) # => [:foo, "bar", "bar", 2]
+ *      a.values_at(0, 2)     # => ["a", "c"]
+ *      a.values_at(0.1, 2.9) # => ["a", "c"]
+ *
+ *  - For each negative numeric +index+ that is in-range (greater than or equal to <tt>- self.size</tt>),
+ *    counts backwards from the end of +self+:
+ *
+ *      a.values_at(-1, -4) # => ["d", "a"]
+ *
+ *  The given indexes may be in any order, and may repeat:
  *
+ *    a.values_at(2, 0, 1, 0, 2) # => ["c", "a", "b", "a", "c"]
+ *
+ *  For each +index+ that is out-of-range, includes +nil+:
+ *
+ *    a.values_at(4, -5) # => [nil, nil]
+ *
+ *  For each Range specifier +range+, includes elements
+ *  according to <tt>range.begin</tt> and <tt>range.end</tt>:
+ *
+ *  - If both <tt>range.begin</tt> and <tt>range.end</tt>
+ *    are non-negative and in-range (less than <tt>self.size</tt>),
+ *    includes elements from index <tt>range.begin</tt>
+ *    through <tt>range.end - 1</tt> (if <tt>range.exclude_end?</tt>),
+ *    or through <tt>range.end</tt> (otherwise):
+ *
+ *      a.values_at(1..2)  # => ["b", "c"]
+ *      a.values_at(1...2) # => ["b"]
+ *
+ *  - If <tt>range.begin</tt> is negative and in-range (greater than or equal to <tt>- self.size</tt>),
+ *    counts backwards from the end of +self+:
+ *
+ *      a.values_at(-2..3) # => ["c", "d"]
+ *
+ *  - If <tt>range.begin</tt> is negative and out-of-range, raises an exception:
+ *
+ *      a.values_at(-5..3) # Raises RangeError.
+ *
+ *  - If <tt>range.end</tt> is positive and out-of-range,
+ *    extends the returned array with +nil+ elements:
+ *
+ *      a.values_at(1..5) # => ["b", "c", "d", nil, nil]
+ *
+ *  - If <tt>range.end</tt> is negative and in-range,
+ *    counts backwards from the end of +self+:
+ *
+ *      a.values_at(1..-2) # => ["b", "c"]
+ *
+ *  - If <tt>range.end</tt> is negative and out-of-range,
+ *    returns an empty array:
+ *
+ *      a.values_at(1..-5) # => []
+ *
+ *  The given ranges may be in any order and may repeat:
+ *
+ *    a.values_at(2..3, 0..1, 2..3) # => ["c", "d", "a", "b", "c", "d"]
+ *
+ *  The given specifiers may be any mixture of indexes and ranges:
+ *
+ *    a.values_at(3, 1..2, 0, 2..3) # => ["d", "b", "c", "a", "c", "d"]
+ *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -3974,23 +3974,22 @@ rb_ary_values_at(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.select {|element| ... } -> new_array
- *    array.select -> new_enumerator
+ *    select {|element| ... } -> new_array
+ *    select -> new_enumerator
+ *    filter {|element| ... } -> new_array
+ *    filter -> new_enumerator
  *
- *  Calls the block, if given, with each element of +self+;
- *  returns a new \Array containing those elements of +self+
+ *  With a block given, calls the block with each element of +self+;
+ *  returns a new array containing those elements of +self+
  *  for which the block returns a truthy value:
  *
  *    a = [:foo, 'bar', 2, :bam]
- *    a1 = a.select {|element| element.to_s.start_with?('b') }
- *    a1 # => ["bar", :bam]
- *
- *  Returns a new \Enumerator if no block given:
+ *    a.select {|element| element.to_s.start_with?('b') }
+ *    # => ["bar", :bam]
  *
- *    a = [:foo, 'bar', 2, :bam]
- *    a.select # => #<Enumerator: [:foo, "bar", 2, :bam]:select>
+ *  With no block given, returns a new Enumerator.
  *
- *  Array#filter is an alias for Array#select.
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -4045,7 +4044,7 @@ select_bang_ensure(VALUE a)
         rb_ary_modify(ary);
         if (i1 < len) {
             tail = len - i1;
-            RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+            RARRAY_PTR_USE(ary, ptr, {
                     MEMMOVE(ptr + i2, ptr + i1, VALUE, tail);
                 });
         }
@@ -4056,10 +4055,12 @@ select_bang_ensure(VALUE a)
 
 /*
  *  call-seq:
- *    array.select! {|element| ... } -> self or nil
- *    array.select! -> new_enumerator
+ *    select! {|element| ... } -> self or nil
+ *    select! -> new_enumerator
+ *    filter! {|element| ... } -> self or nil
+ *    filter! -> new_enumerator
  *
- *  Calls the block, if given  with each element of +self+;
+ *  With a block given, calls the block with each element of +self+;
  *  removes from +self+ those elements for which the block returns +false+ or +nil+.
  *
  *  Returns +self+ if any elements were removed:
@@ -4069,12 +4070,9 @@ select_bang_ensure(VALUE a)
  *
  *  Returns +nil+ if no elements were removed.
  *
- *  Returns a new \Enumerator if no block given:
+ *  With no block given, returns a new Enumerator.
  *
- *    a = [:foo, 'bar', 2, :bam]
- *    a.select! # => #<Enumerator: [:foo, "bar", 2, :bam]:select!>
- *
- *  Array#filter! is an alias for Array#select!.
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 static VALUE
@@ -4092,20 +4090,18 @@ rb_ary_select_bang(VALUE ary)
 
 /*
  *  call-seq:
- *    array.keep_if {|element| ... } -> self
- *    array.keep_if -> new_enumeration
+ *    keep_if {|element| ... } -> self
+ *    keep_if -> new_enumerator
  *
- *  Retains those elements for which the block returns a truthy value;
- *  deletes all other elements; returns +self+:
+ *  With a block given, calls the block with each element of +self+;
+ *  removes the element from +self+ if the block does not return a truthy value:
  *
  *    a = [:foo, 'bar', 2, :bam]
  *    a.keep_if {|element| element.to_s.start_with?('b') } # => ["bar", :bam]
  *
- *  Returns a new \Enumerator if no block given:
- *
- *    a = [:foo, 'bar', 2, :bam]
- *    a.keep_if # => #<Enumerator: [:foo, "bar", 2, :bam]:keep_if>
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 static VALUE
@@ -4131,38 +4127,39 @@ ary_resize_smaller(VALUE ary, long len)
 
 /*
  *  call-seq:
- *    array.delete(obj) -> deleted_object
- *    array.delete(obj) {|nosuch| ... } -> deleted_object or block_return
+ *    delete(object) -> last_removed_object
+ *    delete(object) {|element| ... } -> last_removed_object or block_return
  *
  *  Removes zero or more elements from +self+.
  *
- *  When no block is given,
- *  removes from +self+ each element +ele+ such that <tt>ele == obj</tt>;
- *  returns the last deleted element:
+ *  With no block given,
+ *  removes from +self+ each element +ele+ such that <tt>ele == object</tt>;
+ *  returns the last removed element:
  *
- *    s1 = 'bar'; s2 = 'bar'
- *    a = [:foo, s1, 2, s2]
- *    a.delete('bar') # => "bar"
- *    a # => [:foo, 2]
+ *    a = [0, 1, 2, 2.0]
+ *    a.delete(2) # => 2.0
+ *    a           # => [0, 1]
  *
- *  Returns +nil+ if no elements removed.
+ *  Returns +nil+ if no elements removed:
+ *
+ *    a.delete(2) # => nil
  *
- *  When a block is given,
- *  removes from +self+ each element +ele+ such that <tt>ele == obj</tt>.
+ *  With a block given,
+ *  removes from +self+ each element +ele+ such that <tt>ele == object</tt>.
  *
  *  If any such elements are found, ignores the block
- *  and returns the last deleted element:
+ *  and returns the last removed element:
  *
- *    s1 = 'bar'; s2 = 'bar'
- *    a = [:foo, s1, 2, s2]
- *    deleted_obj = a.delete('bar') {|obj| fail 'Cannot happen' }
- *    a # => [:foo, 2]
+ *    a = [0, 1, 2, 2.0]
+ *    a.delete(2) {|element| fail 'Cannot happen' } # => 2.0
+ *    a                                             # => [0, 1]
  *
- *  If no such elements are found, returns the block's return value:
+ *  If no such element is found, returns the block's return value:
  *
- *    a = [:foo, 'bar', 2]
- *    a.delete(:nosuch) {|obj| "#{obj} not found" } # => "nosuch not found"
+ *    a.delete(2) {|element| "Element #{element} not found." }
+ *    # => "Element 2 not found."
  *
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 VALUE
@@ -4233,7 +4230,7 @@ rb_ary_delete_at(VALUE ary, long pos)
 
     rb_ary_modify(ary);
     del = RARRAY_AREF(ary, pos);
-    RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+    RARRAY_PTR_USE(ary, ptr, {
         MEMMOVE(ptr+pos, ptr+pos+1, VALUE, len-pos-1);
     });
     ARY_INCREASE_LEN(ary, -1);
@@ -4243,9 +4240,10 @@ rb_ary_delete_at(VALUE ary, long pos)
 
 /*
  *  call-seq:
- *    array.delete_at(index) -> deleted_object or nil
+ *    delete_at(index) -> removed_object or nil
  *
- *  Deletes an element from +self+, per the given \Integer +index+.
+ *  Removes the element of +self+ at the given +index+, which must be an
+ *  {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects].
  *
  *  When +index+ is non-negative, deletes the element at offset +index+:
  *
@@ -4253,15 +4251,19 @@ rb_ary_delete_at(VALUE ary, long pos)
  *    a.delete_at(1) # => "bar"
  *    a # => [:foo, 2]
  *
- *  If index is too large, returns +nil+.
- *
  *  When +index+ is negative, counts backward from the end of the array:
  *
  *    a = [:foo, 'bar', 2]
  *    a.delete_at(-2) # => "bar"
  *    a # => [:foo, 2]
  *
- *  If +index+ is too small (far from zero), returns nil.
+ *  When +index+ is out of range, returns +nil+.
+ *
+ *    a = [:foo, 'bar', 2]
+ *    a.delete_at(3)  # => nil
+ *    a.delete_at(-4) # => nil
+ *
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 static VALUE
@@ -4294,7 +4296,7 @@ ary_slice_bang_by_rb_ary_splice(VALUE ary, long pos, long len)
         return rb_ary_new2(0);
     }
     else {
-        VALUE arg2 = rb_ary_new4(len, RARRAY_CONST_PTR_TRANSIENT(ary)+pos);
+        VALUE arg2 = rb_ary_new4(len, RARRAY_CONST_PTR(ary)+pos);
         rb_ary_splice(ary, pos, len, 0, 0);
         return arg2;
     }
@@ -4302,71 +4304,94 @@ ary_slice_bang_by_rb_ary_splice(VALUE ary, long pos, long len)
 
 /*
  *  call-seq:
- *    array.slice!(n) -> object or nil
- *    array.slice!(start, length) -> new_array or nil
- *    array.slice!(range) -> new_array or nil
+ *    slice!(index) -> object or nil
+ *    slice!(start, length) -> new_array or nil
+ *    slice!(range) -> new_array or nil
  *
  *  Removes and returns elements from +self+.
  *
- *  When the only argument is an \Integer +n+,
- *  removes and returns the _nth_ element in +self+:
+ *  With numeric argument +index+ given,
+ *  removes and returns the element at offset +index+:
  *
- *    a = [:foo, 'bar', 2]
- *    a.slice!(1) # => "bar"
- *    a # => [:foo, 2]
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(2)   # => "c"
+ *    a             # => ["a", "b", "d"]
+ *    a.slice!(2.1) # => "d"
+ *    a             # => ["a", "b"]
  *
- *  If +n+ is negative, counts backwards from the end of +self+:
+ *  If +index+ is negative, counts backwards from the end of +self+:
  *
- *    a = [:foo, 'bar', 2]
- *    a.slice!(-1) # => 2
- *    a # => [:foo, "bar"]
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(-2) # => "c"
+ *    a            # => ["a", "b", "d"]
  *
- *  If +n+ is out of range, returns +nil+.
+ *  If +index+ is out of range, returns +nil+.
  *
- *  When the only arguments are Integers +start+ and +length+,
- *  removes +length+ elements from +self+ beginning at offset  +start+;
- *  returns the deleted objects in a new \Array:
+ *  With numeric arguments +start+ and +length+ given,
+ *  removes +length+ elements from +self+ beginning at zero-based offset +start+;
+ *  returns the removed objects in a new array:
  *
- *    a = [:foo, 'bar', 2]
- *    a.slice!(0, 2) # => [:foo, "bar"]
- *    a # => [2]
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(1, 2)     # => ["b", "c"]
+ *    a                  # => ["a", "d"]
+ *    a.slice!(0.1, 1.1) # => ["a"]
+ *    a                  # => ["d"]
+ *
+ *  If +start+ is negative, counts backwards from the end of +self+:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(-2, 1) # => ["c"]
+ *    a               # => ["a", "b", "d"]
+ *
+ *  If +start+ is out-of-range, returns +nil+:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(5, 1)  # => nil
+ *    a.slice!(-5, 1) # => nil
  *
  *  If <tt>start + length</tt> exceeds the array size,
  *  removes and returns all elements from offset +start+ to the end:
  *
- *    a = [:foo, 'bar', 2]
- *    a.slice!(1, 50) # => ["bar", 2]
- *    a # => [:foo]
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(2, 50) # => ["c", "d"]
+ *    a               # => ["a", "b"]
  *
  *  If <tt>start == a.size</tt> and +length+ is non-negative,
- *  returns a new empty \Array.
+ *  returns a new empty array.
  *
  *  If +length+ is negative, returns +nil+.
  *
- *  When the only argument is a \Range object +range+,
- *  treats <tt>range.min</tt> as +start+ above and <tt>range.size</tt> as +length+ above:
+ *  With Range argument +range+ given,
+ *  treats <tt>range.min</tt> as +start+ (as above)
+ *  and <tt>range.size</tt> as +length+ (as above):
  *
- *    a = [:foo, 'bar', 2]
- *    a.slice!(1..2) # => ["bar", 2]
- *    a # => [:foo]
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(1..2) # => ["b", "c"]
+ *    a              # => ["a", "d"]
  *
- *  If <tt>range.start == a.size</tt>, returns a new empty \Array.
+ *  If <tt>range.start == a.size</tt>, returns a new empty array:
  *
- *  If <tt>range.start</tt> is larger than the array size, returns +nil+.
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(4..5) # => []
  *
- *  If <tt>range.end</tt> is negative, counts backwards from the end of the array:
+ *  If <tt>range.start</tt> is larger than the array size, returns +nil+:
  *
- *    a = [:foo, 'bar', 2]
- *    a.slice!(0..-2) # => [:foo, "bar"]
- *    a # => [2]
+ *    a = ['a', 'b', 'c', 'd']
+      a.slice!(5..6) # => nil
  *
  *  If <tt>range.start</tt> is negative,
- *  calculates the start index backwards from the end of the array:
+ *  calculates the start index by counting backwards from the end of +self+:
  *
- *    a = [:foo, 'bar', 2]
- *    a.slice!(-2..2) # => ["bar", 2]
- *    a # => [:foo]
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(-2..2) # => ["c"]
+ *
+ *  If <tt>range.end</tt> is negative,
+ *  calculates the end index by counting backwards from the end of +self+:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.slice!(0..-2) # => ["a", "b", "c"]
  *
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 static VALUE
@@ -4447,10 +4472,11 @@ ary_reject_bang(VALUE ary)
 
 /*
  *  call-seq:
- *    array.reject! {|element| ... } -> self or nil
- *    array.reject! -> new_enumerator
+ *    reject! {|element| ... } -> self or nil
+ *    reject! -> new_enumerator
  *
- *  Removes each element for which the block returns a truthy value.
+ *  With a block given, calls the block with each element of +self+;
+ *  removes each element for which the block returns a truthy value.
  *
  *  Returns +self+ if any elements removed:
  *
@@ -4459,11 +4485,9 @@ ary_reject_bang(VALUE ary)
  *
  *  Returns +nil+ if no elements removed.
  *
- *  Returns a new \Enumerator if no block given:
- *
- *    a = [:foo, 'bar', 2]
- *    a.reject! # => #<Enumerator: [:foo, "bar", 2]:reject!>
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 static VALUE
@@ -4476,21 +4500,19 @@ rb_ary_reject_bang(VALUE ary)
 
 /*
  *  call-seq:
- *    array.reject {|element| ... } -> new_array
- *    array.reject -> new_enumerator
+ *    reject {|element| ... } -> new_array
+ *    reject -> new_enumerator
  *
- *  Returns a new \Array whose elements are all those from +self+
+ *  With a block given, returns a new array whose elements are all those from +self+
  *  for which the block returns +false+ or +nil+:
  *
  *    a = [:foo, 'bar', 2, 'bat']
  *    a1 = a.reject {|element| element.to_s.start_with?('b') }
  *    a1 # => [:foo, 2]
  *
- *  Returns a new \Enumerator if no block given:
- *
- *     a = [:foo, 'bar', 2]
- *     a.reject # => #<Enumerator: [:foo, "bar", 2]:reject>
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -4506,21 +4528,20 @@ rb_ary_reject(VALUE ary)
 
 /*
  *  call-seq:
- *    array.delete_if {|element| ... } -> self
- *    array.delete_if -> Enumerator
+ *    delete_if {|element| ... } -> self
+ *    delete_if -> new_numerator
  *
- *  Removes each element in +self+ for which the block returns a truthy value;
+ *  With a block given, calls the block with each element of +self+;
+ *  removes the element if the block returns a truthy value;
  *  returns +self+:
  *
  *    a = [:foo, 'bar', 2, 'bat']
  *    a.delete_if {|element| element.to_s.start_with?('b') } # => [:foo, 2]
  *
- *  Returns a new \Enumerator if no block given:
+ *  With no block given, returns a new Enumerator.
  *
- *    a = [:foo, 'bar', 2]
- *    a.delete_if # => #<Enumerator: [:foo, "bar", 2]:delete_if>
- *
-3 */
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
+ */
 
 static VALUE
 rb_ary_delete_if(VALUE ary)
@@ -4551,7 +4572,7 @@ take_items(VALUE obj, long n)
     if (!NIL_P(result)) return rb_ary_subseq(result, 0, n);
     result = rb_ary_new2(n);
     args[0] = result; args[1] = (VALUE)n;
-    if (rb_check_block_call(obj, idEach, 0, 0, take_i, (VALUE)args) == Qundef)
+    if (UNDEF_P(rb_check_block_call(obj, idEach, 0, 0, take_i, (VALUE)args)))
         rb_raise(rb_eTypeError, "wrong argument type %"PRIsVALUE" (must respond to :each)",
                  rb_obj_class(obj));
     return result;
@@ -4560,58 +4581,95 @@ take_items(VALUE obj, long n)
 
 /*
  *  call-seq:
- *    array.zip(*other_arrays) -> new_array
- *    array.zip(*other_arrays) {|other_array| ... } -> nil
+ *    zip(*other_arrays) -> new_array
+ *    zip(*other_arrays) {|sub_array| ... } -> nil
  *
- *  When no block given, returns a new \Array +new_array+ of size <tt>self.size</tt>
- *  whose elements are Arrays.
+ *  With no block given, combines +self+ with the collection of +other_arrays+;
+ *  returns a new array of sub-arrays:
  *
- *  Each nested array <tt>new_array[n]</tt> is of size <tt>other_arrays.size+1</tt>,
- *  and contains:
+ *    [0, 1].zip(['zero', 'one'], [:zero, :one])
+ *    # => [[0, "zero", :zero], [1, "one", :one]]
  *
- *  - The _nth_ element of +self+.
- *  - The _nth_ element of each of the +other_arrays+.
+ *  Returned:
+ *
+ *  - The outer array is of size <tt>self.size</tt>.
+ *  - Each sub-array is of size <tt>other_arrays.size + 1</tt>.
+ *  - The _nth_ sub-array contains (in order):
+ *
+ *    - The _nth_ element of +self+.
+ *    - The _nth_ element of each of the other arrays, as available.
+ *
+ *  Example:
+ *
+ *    a = [0, 1]
+ *    zipped = a.zip(['zero', 'one'], [:zero, :one])
+ *    # => [[0, "zero", :zero], [1, "one", :one]]
+ *    zipped.size       # => 2 # Same size as a.
+ *    zipped.first.size # => 3 # Size of other arrays plus 1.
  *
- *  If all +other_arrays+ and +self+ are the same size:
+ *  When the other arrays are all the same size as +self+,
+ *  the returned sub-arrays are a rearrangement containing exactly elements of all the arrays
+ *  (including +self+), with no omissions or additions:
  *
  *    a = [:a0, :a1, :a2, :a3]
  *    b = [:b0, :b1, :b2, :b3]
  *    c = [:c0, :c1, :c2, :c3]
  *    d = a.zip(b, c)
- *    d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]]
+ *    pp d
+ *    # =>
+ *    [[:a0, :b0, :c0],
+ *     [:a1, :b1, :c1],
+ *     [:a2, :b2, :c2],
+ *     [:a3, :b3, :c3]]
  *
- *  If any array in +other_arrays+ is smaller than +self+,
- *  fills to <tt>self.size</tt> with +nil+:
+ *  When one of the other arrays is smaller than +self+,
+ *  pads the corresponding sub-array with +nil+ elements:
  *
  *    a = [:a0, :a1, :a2, :a3]
  *    b = [:b0, :b1, :b2]
  *    c = [:c0, :c1]
  *    d = a.zip(b, c)
- *    d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, nil], [:a3, nil, nil]]
+ *    pp d
+ *    # =>
+ *    [[:a0, :b0, :c0],
+ *     [:a1, :b1, :c1],
+ *     [:a2, :b2, nil],
+ *     [:a3, nil, nil]]
  *
- *  If any array in +other_arrays+ is larger than +self+,
- *  its trailing elements are ignored:
+ *  When one of the other arrays is larger than +self+,
+ *  _ignores_ its trailing elements:
  *
  *    a = [:a0, :a1, :a2, :a3]
  *    b = [:b0, :b1, :b2, :b3, :b4]
  *    c = [:c0, :c1, :c2, :c3, :c4, :c5]
  *    d = a.zip(b, c)
- *    d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]]
+ *    pp d
+ *    # =>
+ *    [[:a0, :b0, :c0],
+ *     [:a1, :b1, :c1],
+ *     [:a2, :b2, :c2],
+ *     [:a3, :b3, :c3]]
  *
- *  When a block is given, calls the block with each of the sub-arrays (formed as above); returns +nil+:
+ *  With a block given, calls the block with each of the other arrays;
+ *  returns +nil+:
  *
+ *    d = []
  *    a = [:a0, :a1, :a2, :a3]
  *    b = [:b0, :b1, :b2, :b3]
  *    c = [:c0, :c1, :c2, :c3]
- *    a.zip(b, c) {|sub_array| p sub_array} # => nil
- *
- *  Output:
- *
- *    [:a0, :b0, :c0]
- *    [:a1, :b1, :c1]
- *    [:a2, :b2, :c2]
- *    [:a3, :b3, :c3]
- *
+ *    a.zip(b, c) {|sub_array| d.push(sub_array.reverse) } # => nil
+ *    pp d
+ *    # =>
+ *    [[:c0, :b0, :a0],
+ *     [:c1, :b1, :a1],
+ *     [:c2, :b2, :a2],
+ *     [:c3, :b3, :a3]]
+ *
+ *  For an *object* in *other_arrays* that is not actually an array,
+ *  forms the "other array" as <tt>object.to_ary</tt>, if defined,
+ *  or as <tt>object.each.to_a</tt> otherwise.
+ *
+ *  Related: see {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].
  */
 
 static VALUE
@@ -4674,14 +4732,17 @@ rb_ary_zip(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.transpose -> new_array
+ *    transpose -> new_array
  *
- *  Transposes the rows and columns in an \Array of Arrays;
- *  the nested Arrays must all be the same size:
+ *  Returns a new array that is +self+
+ *  as a {transposed matrix}[https://en.wikipedia.org/wiki/Transpose]:
  *
  *    a = [[:a0, :a1], [:b0, :b1], [:c0, :c1]]
  *    a.transpose # => [[:a0, :b0, :c0], [:a1, :b1, :c1]]
  *
+ *  The elements of +self+ must all be the same size.
+ *
+ *  Related: see {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].
  */
 
 static VALUE
@@ -4714,13 +4775,17 @@ rb_ary_transpose(VALUE ary)
 
 /*
  *  call-seq:
- *    array.replace(other_array) -> self
+ *    initialize_copy(other_array) -> self
+ *    replace(other_array) -> self
  *
- *  Replaces the content of +self+ with the content of +other_array+; returns +self+:
+ *  Replaces the elements of +self+ with the elements of +other_array+, which must be an
+ *  {array-convertible object}[rdoc-ref:implicit_conversion.rdoc@Array-Convertible+Objects];
+ *  returns +self+:
  *
- *    a = [:foo, 'bar', 2]
- *    a.replace(['foo', :bar, 3]) # => ["foo", :bar, 3]
+ *    a = ['a', 'b', 'c']   # => ["a", "b", "c"]
+ *    a.replace(['d', 'e']) # => ["d", "e"]
  *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 VALUE
@@ -4734,16 +4799,15 @@ rb_ary_replace(VALUE copy, VALUE orig)
 
     /* orig has enough space to embed the contents of orig. */
     if (RARRAY_LEN(orig) <= ary_embed_capa(copy)) {
-        assert(ARY_EMBED_P(copy));
-        ary_memcpy(copy, 0, RARRAY_LEN(orig), RARRAY_CONST_PTR_TRANSIENT(orig));
+        RUBY_ASSERT(ARY_EMBED_P(copy));
+        ary_memcpy(copy, 0, RARRAY_LEN(orig), RARRAY_CONST_PTR(orig));
         ARY_SET_EMBED_LEN(copy, RARRAY_LEN(orig));
     }
-#if USE_RVARGC
     /* orig is embedded but copy does not have enough space to embed the
      * contents of orig. */
     else if (ARY_EMBED_P(orig)) {
         long len = ARY_EMBED_LEN(orig);
-        VALUE *ptr = ary_heap_alloc(copy, len);
+        VALUE *ptr = ary_heap_alloc_buffer(len);
 
         FL_UNSET_EMBED(copy);
         ARY_SET_PTR(copy, ptr);
@@ -4752,9 +4816,8 @@ rb_ary_replace(VALUE copy, VALUE orig)
 
         // No allocation and exception expected that could leave `copy` in a
         // bad state from the edits above.
-        ary_memcpy(copy, 0, len, RARRAY_CONST_PTR_TRANSIENT(orig));
+        ary_memcpy(copy, 0, len, RARRAY_CONST_PTR(orig));
     }
-#endif
     /* Otherwise, orig is on heap and copy does not have enough space to embed
      * the contents of orig. */
     else {
@@ -4763,6 +4826,8 @@ rb_ary_replace(VALUE copy, VALUE orig)
         ARY_SET_PTR(copy, ARY_HEAP_PTR(orig));
         ARY_SET_LEN(copy, ARY_HEAP_LEN(orig));
         rb_ary_set_shared(copy, shared_root);
+
+        RUBY_ASSERT(RB_OBJ_SHAREABLE_P(copy) ? RB_OBJ_SHAREABLE_P(shared_root) : 1);
     }
     ary_verify(copy);
     return copy;
@@ -4770,13 +4835,14 @@ rb_ary_replace(VALUE copy, VALUE orig)
 
 /*
  *  call-seq:
- *     array.clear -> self
+ *    clear -> self
  *
- *  Removes all elements from +self+:
+ *  Removes all elements from +self+; returns +self+:
  *
  *    a = [:foo, 'bar', 2]
  *    a.clear # => []
  *
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 VALUE
@@ -4784,11 +4850,9 @@ rb_ary_clear(VALUE ary)
 {
     rb_ary_modify_check(ary);
     if (ARY_SHARED_P(ary)) {
-        if (!ARY_EMBED_P(ary)) {
-            rb_ary_unshare(ary);
-            FL_SET_EMBED(ary);
-            ARY_SET_EMBED_LEN(ary, 0);
-        }
+        rb_ary_unshare(ary);
+        FL_SET_EMBED(ary);
+        ARY_SET_EMBED_LEN(ary, 0);
     }
     else {
         ARY_SET_LEN(ary, 0);
@@ -4802,198 +4866,182 @@ rb_ary_clear(VALUE ary)
 
 /*
  *  call-seq:
- *    array.fill(obj) -> self
- *    array.fill(obj, start) -> self
- *    array.fill(obj, start, length) -> self
- *    array.fill(obj, range) -> self
- *    array.fill {|index| ... } -> self
- *    array.fill(start) {|index| ... } -> self
- *    array.fill(start, length) {|index| ... } -> self
- *    array.fill(range) {|index| ... } -> self
- *
- *  Replaces specified elements in +self+ with specified objects; returns +self+.
- *
- *  With argument +obj+ and no block given, replaces all elements with that one object:
- *
- *    a = ['a', 'b', 'c', 'd']
- *    a # => ["a", "b", "c", "d"]
- *    a.fill(:X) # => [:X, :X, :X, :X]
+ *    fill(object, start = nil, count = nil) -> self
+ *    fill(object, range) -> self
+ *    fill(start = nil, count = nil) {|element| ... } -> self
+ *    fill(range) {|element| ... } -> self
  *
- *  With arguments +obj+ and \Integer +start+, and no block given,
- *  replaces elements based on the given start.
+ *  Replaces selected elements in +self+;
+ *  may add elements to +self+;
+ *  always returns +self+ (never a new array).
  *
- *  If +start+ is in range (<tt>0 <= start < array.size</tt>),
- *  replaces all elements from offset +start+ through the end:
- *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, 2) # => ["a", "b", :X, :X]
- *
- *  If +start+ is too large (<tt>start >= array.size</tt>), does nothing:
- *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, 4) # => ["a", "b", "c", "d"]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, 5) # => ["a", "b", "c", "d"]
+ *  In brief:
  *
- *  If +start+ is negative, counts from the end (starting index is <tt>start + array.size</tt>):
+ *    # Non-negative start.
+ *    ['a', 'b', 'c', 'd'].fill('-', 1, 2)          # => ["a", "-", "-", "d"]
+ *    ['a', 'b', 'c', 'd'].fill(1, 2) {|e| e.to_s } # => ["a", "1", "2", "d"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, -2) # => ["a", "b", :X, :X]
+ *    # Extends with specified values if necessary.
+ *    ['a', 'b', 'c', 'd'].fill('-', 3, 2)          # => ["a", "b", "c", "-", "-"]
+ *    ['a', 'b', 'c', 'd'].fill(3, 2) {|e| e.to_s } # => ["a", "b", "c", "3", "4"]
  *
- *  If +start+ is too small (less than and far from zero), replaces all elements:
+ *    # Fills with nils if necessary.
+ *    ['a', 'b', 'c', 'd'].fill('-', 6, 2)          # => ["a", "b", "c", "d", nil, nil, "-", "-"]
+ *    ['a', 'b', 'c', 'd'].fill(6, 2) {|e| e.to_s } # => ["a", "b", "c", "d", nil, nil, "6", "7"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, -6) # => [:X, :X, :X, :X]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, -50) # => [:X, :X, :X, :X]
+ *    # For negative start, counts backwards from the end.
+ *    ['a', 'b', 'c', 'd'].fill('-', -3, 3)          # => ["a", "-", "-", "-"]
+ *    ['a', 'b', 'c', 'd'].fill(-3, 3) {|e| e.to_s } # => ["a", "1", "2", "3"]
  *
- *  With arguments +obj+, \Integer +start+, and \Integer +length+, and no block given,
- *  replaces elements based on the given +start+ and +length+.
+ *    # Range.
+ *    ['a', 'b', 'c', 'd'].fill('-', 1..2)          # => ["a", "-", "-", "d"]
+ *    ['a', 'b', 'c', 'd'].fill(1..2) {|e| e.to_s } # => ["a", "1", "2", "d"]
  *
- *  If +start+ is in range, replaces +length+ elements beginning at offset +start+:
+ *  When arguments +start+ and +count+ are given,
+ *  they select the elements of +self+ to be replaced;
+ *  each must be an
+ *  {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects]
+ *  (or +nil+):
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, 1, 1) # => ["a", :X, "c", "d"]
+ *  - +start+ specifies the zero-based offset of the first element to be replaced;
+ *    +nil+ means zero.
+ *  - +count+ is the number of consecutive elements to be replaced;
+ *    +nil+ means "all the rest."
  *
- *  If +start+ is negative, counts from the end:
+ *  With argument +object+ given,
+ *  that one object is used for all replacements:
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, -2, 1) # => ["a", "b", :X, "d"]
+ *    o = Object.new           # => #<Object:0x0000014e7bff7600>
+ *    a = ['a', 'b', 'c', 'd'] # => ["a", "b", "c", "d"]
+ *    a.fill(o, 1, 2)
+ *    # => ["a", #<Object:0x0000014e7bff7600>, #<Object:0x0000014e7bff7600>, "d"]
  *
- *  If +start+ is large (<tt>start >= array.size</tt>), extends +self+ with +nil+:
+ *  With a block given, the block is called once for each element to be replaced;
+ *  the value passed to the block is the _index_ of the element to be replaced
+ *  (not the element itself);
+ *  the block's return value replaces the element:
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, 5, 0) # => ["a", "b", "c", "d", nil]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, 5, 2) # => ["a", "b", "c", "d", nil, :X, :X]
+ *    a = ['a', 'b', 'c', 'd']               # => ["a", "b", "c", "d"]
+ *    a.fill(1, 2) {|element| element.to_s } # => ["a", "1", "2", "d"]
  *
- *  If +length+ is zero or negative, replaces no elements:
+ *  For arguments +start+ and +count+:
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, 1, 0) # => ["a", "b", "c", "d"]
- *    a.fill(:X, 1, -1) # => ["a", "b", "c", "d"]
+ *  - If +start+ is non-negative,
+ *    replaces +count+ elements beginning at offset +start+:
  *
- *  With arguments +obj+ and \Range +range+, and no block given,
- *  replaces elements based on the given range.
+ *      ['a', 'b', 'c', 'd'].fill('-', 0, 2) # => ["-", "-", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 1, 2) # => ["a", "-", "-", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 2, 2) # => ["a", "b", "-", "-"]
  *
- *  If the range is positive and ascending (<tt>0 < range.begin <= range.end</tt>),
- *  replaces elements from <tt>range.begin</tt> to <tt>range.end</tt>:
+ *      ['a', 'b', 'c', 'd'].fill(0, 2) {|e| e.to_s } # => ["0", "1", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(1, 2) {|e| e.to_s } # => ["a", "1", "2", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(2, 2) {|e| e.to_s } # => ["a", "b", "2", "3"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, (1..1)) # => ["a", :X, "c", "d"]
+ *    Extends +self+ if necessary:
  *
- *  If <tt>range.first</tt> is negative, replaces no elements:
+ *      ['a', 'b', 'c', 'd'].fill('-', 3, 2) # => ["a", "b", "c", "-", "-"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 4, 2) # => ["a", "b", "c", "d", "-", "-"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, (-1..1)) # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(3, 2) {|e| e.to_s } # => ["a", "b", "c", "3", "4"]
+ *      ['a', 'b', 'c', 'd'].fill(4, 2) {|e| e.to_s } # => ["a", "b", "c", "d", "4", "5"]
  *
- *  If <tt>range.last</tt> is negative, counts from the end:
+ *    Fills with +nil+ if necessary:
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, (0..-2)) # => [:X, :X, :X, "d"]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, (1..-2)) # => ["a", :X, :X, "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 5, 2) # => ["a", "b", "c", "d", nil, "-", "-"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 6, 2) # => ["a", "b", "c", "d", nil, nil, "-", "-"]
  *
- *  If <tt>range.last</tt> and <tt>range.last</tt> are both negative,
- *  both count from the end of the array:
+ *      ['a', 'b', 'c', 'd'].fill(5, 2) {|e| e.to_s } # => ["a", "b", "c", "d", nil, "5", "6"]
+ *      ['a', 'b', 'c', 'd'].fill(6, 2) {|e| e.to_s } # => ["a", "b", "c", "d", nil, nil, "6", "7"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, (-1..-1)) # => ["a", "b", "c", :X]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(:X, (-2..-2)) # => ["a", "b", :X, "d"]
+ *    Does nothing if +count+ is non-positive:
  *
- *  With no arguments and a block given, calls the block with each index;
- *  replaces the corresponding element with the block's return value:
+ *      ['a', 'b', 'c', 'd'].fill('-', 2, 0)    # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 2, -100) # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 6, -100) # => ["a", "b", "c", "d"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill { |index| "new_#{index}" } # => ["new_0", "new_1", "new_2", "new_3"]
+ *      ['a', 'b', 'c', 'd'].fill(2, 0) {|e| fail 'Cannot happen' }    # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(2, -100) {|e| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(6, -100) {|e| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
  *
- *  With argument +start+ and a block given, calls the block with each index
- *  from offset +start+ to the end; replaces the corresponding element
- *  with the block's return value.
+ *  - If +start+ is negative, counts backwards from the end of +self+:
  *
- *  If start is in range (<tt>0 <= start < array.size</tt>),
- *  replaces from offset +start+ to the end:
+ *      ['a', 'b', 'c', 'd'].fill('-', -4, 3) # => ["-", "-", "-", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', -3, 3) # => ["a", "-", "-", "-"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(1) { |index| "new_#{index}" } # => ["a", "new_1", "new_2", "new_3"]
+ *      ['a', 'b', 'c', 'd'].fill(-4, 3) {|e| e.to_s } # => ["0", "1", "2", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(-3, 3) {|e| e.to_s } # => ["a", "1", "2", "3"]
  *
- *  If +start+ is too large(<tt>start >= array.size</tt>), does nothing:
+ *    Extends +self+ if necessary:
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(4) { |index| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(4) { |index| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', -2, 3) # => ["a", "b", "-", "-", "-"]
+ *      ['a', 'b', 'c', 'd'].fill('-', -1, 3) # => ["a", "b", "c", "-", "-", "-"]
  *
- *  If +start+ is negative, counts from the end:
+ *      ['a', 'b', 'c', 'd'].fill(-2, 3) {|e| e.to_s } # => ["a", "b", "2", "3", "4"]
+ *      ['a', 'b', 'c', 'd'].fill(-1, 3) {|e| e.to_s } # => ["a", "b", "c", "3", "4", "5"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(-2) { |index| "new_#{index}" } # => ["a", "b", "new_2", "new_3"]
+ *    Starts at the beginning of +self+ if +start+ is negative and out-of-range:
  *
- *  If start is too small (<tt>start <= -array.size</tt>, replaces all elements:
+ *      ['a', 'b', 'c', 'd'].fill('-', -5, 2) # => ["-", "-", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', -6, 2) # => ["-", "-", "c", "d"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(-6) { |index| "new_#{index}" } # => ["new_0", "new_1", "new_2", "new_3"]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(-50) { |index| "new_#{index}" } # => ["new_0", "new_1", "new_2", "new_3"]
+ *      ['a', 'b', 'c', 'd'].fill(-5, 2) {|e| e.to_s } # => ["0", "1", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(-6, 2) {|e| e.to_s } # => ["0", "1", "c", "d"]
  *
- *  With arguments +start+ and +length+, and a block given,
- *  calls the block for each index specified by start length;
- *  replaces the corresponding element with the block's return value.
+ *    Does nothing if +count+ is non-positive:
  *
- *  If +start+ is in range, replaces +length+ elements beginning at offset +start+:
+ *      ['a', 'b', 'c', 'd'].fill('-', -2, 0)  # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', -2, -1) # => ["a", "b", "c", "d"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(1, 1) { |index| "new_#{index}" } # => ["a", "new_1", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(-2, 0) {|e| fail 'Cannot happen' }  # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(-2, -1) {|e| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
  *
- *  If start is negative, counts from the end:
+ *  When argument +range+ is given,
+ *  it must be a Range object whose members are numeric;
+ *  its +begin+ and +end+ values determine the elements of +self+
+ *  to be replaced:
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(-2, 1) { |index| "new_#{index}" } # => ["a", "b", "new_2", "d"]
+ *  - If both +begin+ and +end+ are positive, they specify the first and last elements
+ *    to be replaced:
  *
- *  If +start+ is large (<tt>start >= array.size</tt>), extends +self+ with +nil+:
+ *      ['a', 'b', 'c', 'd'].fill('-', 1..2)          # => ["a", "-", "-", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(1..2) {|e| e.to_s } # => ["a", "1", "2", "d"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(5, 0) { |index| "new_#{index}" } # => ["a", "b", "c", "d", nil]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(5, 2) { |index| "new_#{index}" } # => ["a", "b", "c", "d", nil, "new_5", "new_6"]
+ *    If +end+ is smaller than +begin+, replaces no elements:
  *
- *  If +length+ is zero or less, replaces no elements:
+ *      ['a', 'b', 'c', 'd'].fill('-', 2..1)          # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(2..1) {|e| e.to_s } # => ["a", "b", "c", "d"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(1, 0) { |index| "new_#{index}" } # => ["a", "b", "c", "d"]
- *    a.fill(1, -1) { |index| "new_#{index}" } # => ["a", "b", "c", "d"]
+ *  - If either is negative (or both are negative), counts backwards from the end of +self+:
  *
- *  With arguments +obj+ and +range+, and a block given,
- *  calls the block with each index in the given range;
- *  replaces the corresponding element with the block's return value.
+ *      ['a', 'b', 'c', 'd'].fill('-', -3..2)  # => ["a", "-", "-", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 1..-2)  # => ["a", "-", "-", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', -3..-2) # => ["a", "-", "-", "d"]
  *
- *  If the range is positive and ascending (<tt>range 0 < range.begin <= range.end</tt>,
- *  replaces elements from <tt>range.begin</tt> to <tt>range.end</tt>:
+ *      ['a', 'b', 'c', 'd'].fill(-3..2) {|e| e.to_s }  # => ["a", "1", "2", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(1..-2) {|e| e.to_s }  # => ["a", "1", "2", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(-3..-2) {|e| e.to_s } # => ["a", "1", "2", "d"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(1..1) { |index| "new_#{index}" } # => ["a", "new_1", "c", "d"]
+ *  - If the +end+ value is excluded (see Range#exclude_end?), omits the last replacement:
  *
- *  If +range.first+ is negative, does nothing:
+ *      ['a', 'b', 'c', 'd'].fill('-', 1...2)  # => ["a", "-", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 1...-2) # => ["a", "-", "c", "d"]
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(-1..1) { |index| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(1...2) {|e| e.to_s }  # => ["a", "1", "c", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(1...-2) {|e| e.to_s } # => ["a", "1", "c", "d"]
  *
- *  If <tt>range.last</tt> is negative, counts from the end:
+ *  - If the range is endless (see {Endless Ranges}[rdoc-ref:Range@Endless+Ranges]),
+ *    replaces elements to the end of +self+:
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(0..-2) { |index| "new_#{index}" } # => ["new_0", "new_1", "new_2", "d"]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(1..-2) { |index| "new_#{index}" } # => ["a", "new_1", "new_2", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', 1..)          # => ["a", "-", "-", "-"]
+ *      ['a', 'b', 'c', 'd'].fill(1..) {|e| e.to_s } # => ["a", "1", "2", "3"]
  *
- *  If <tt>range.first</tt> and <tt>range.last</tt> are both negative,
- *  both count from the end:
+ *  - If the range is beginless (see {Beginless Ranges}[rdoc-ref:Range@Beginless+Ranges]),
+ *    replaces elements from the beginning of +self+:
  *
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(-1..-1) { |index| "new_#{index}" } # => ["a", "b", "c", "new_3"]
- *    a = ['a', 'b', 'c', 'd']
- *    a.fill(-2..-2) { |index| "new_#{index}" } # => ["a", "b", "new_2", "d"]
+ *      ['a', 'b', 'c', 'd'].fill('-', ..2)          # => ["-", "-", "-", "d"]
+ *      ['a', 'b', 'c', 'd'].fill(..2) {|e| e.to_s } # => ["0", "1", "2", "d"]
  *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 static VALUE
@@ -5044,7 +5092,7 @@ rb_ary_fill(int argc, VALUE *argv, VALUE ary)
         ARY_SET_LEN(ary, end);
     }
 
-    if (item == Qundef) {
+    if (UNDEF_P(item)) {
         VALUE v;
         long i;
 
@@ -5062,15 +5110,15 @@ rb_ary_fill(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array + other_array -> new_array
+ *    self + other_array -> new_array
  *
- *  Returns a new \Array containing all elements of +array+
+ *  Returns a new array containing all elements of +self+
  *  followed by all elements of +other_array+:
  *
  *    a = [0, 1] + [2, 3]
  *    a # => [0, 1, 2, 3]
  *
- *  Related: #concat.
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
 VALUE
@@ -5085,8 +5133,8 @@ rb_ary_plus(VALUE x, VALUE y)
     len = xlen + ylen;
     z = rb_ary_new2(len);
 
-    ary_memcpy(z, 0, xlen, RARRAY_CONST_PTR_TRANSIENT(x));
-    ary_memcpy(z, xlen, ylen, RARRAY_CONST_PTR_TRANSIENT(y));
+    ary_memcpy(z, 0, xlen, RARRAY_CONST_PTR(x));
+    ary_memcpy(z, xlen, ylen, RARRAY_CONST_PTR(y));
     ARY_SET_LEN(z, len);
     return z;
 }
@@ -5096,7 +5144,7 @@ ary_append(VALUE x, VALUE y)
 {
     long n = RARRAY_LEN(y);
     if (n > 0) {
-        rb_ary_splice(x, RARRAY_LEN(x), 0, RARRAY_CONST_PTR_TRANSIENT(y), n);
+        rb_ary_splice(x, RARRAY_LEN(x), 0, RARRAY_CONST_PTR(y), n);
     }
     RB_GC_GUARD(y);
     return x;
@@ -5104,12 +5152,15 @@ ary_append(VALUE x, VALUE y)
 
 /*
  *  call-seq:
- *    array.concat(*other_arrays) -> self
+ *    concat(*other_arrays) -> self
  *
- *  Adds to +array+ all elements from each \Array in +other_arrays+; returns +self+:
+ *  Adds to +self+ all elements from each array in +other_arrays+; returns +self+:
  *
  *    a = [0, 1]
- *    a.concat([2, 3], [4, 5]) # => [0, 1, 2, 3, 4, 5]
+ *    a.concat(['two', 'three'], [:four, :five], a)
+ *    # => [0, 1, "two", "three", :four, :five, 0, 1]
+ *
+ *  Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 static VALUE
@@ -5141,19 +5192,19 @@ rb_ary_concat(VALUE x, VALUE y)
 
 /*
  *  call-seq:
- *    array * n -> new_array
- *    array * string_separator -> new_string
+ *    self * n -> new_array
+ *    self * string_separator -> new_string
  *
- *  When non-negative argument \Integer +n+ is given,
- *  returns a new \Array built by concatenating the +n+ copies of +self+:
+ *  When non-negative integer argument +n+ is given,
+ *  returns a new array built by concatenating +n+ copies of +self+:
  *
  *    a = ['x', 'y']
  *    a * 3 # => ["x", "y", "x", "y", "x", "y"]
  *
- *  When \String argument +string_separator+ is given,
- *  equivalent to <tt>array.join(string_separator)</tt>:
+ *  When string argument +string_separator+ is given,
+ *  equivalent to <tt>self.join(string_separator)</tt>:
  *
- *    [0, [0, 1], {foo: 0}] * ', ' # => "0, 0, 1, {:foo=>0}"
+ *    [0, [0, 1], {foo: 0}] * ', ' # => "0, 0, 1, {foo: 0}"
  *
  */
 
@@ -5185,16 +5236,16 @@ rb_ary_times(VALUE ary, VALUE times)
     ary2 = ary_new(rb_cArray, len);
     ARY_SET_LEN(ary2, len);
 
-    ptr = RARRAY_CONST_PTR_TRANSIENT(ary);
+    ptr = RARRAY_CONST_PTR(ary);
     t = RARRAY_LEN(ary);
     if (0 < t) {
         ary_memcpy(ary2, 0, t, ptr);
         while (t <= len/2) {
-            ary_memcpy(ary2, t, t, RARRAY_CONST_PTR_TRANSIENT(ary2));
+            ary_memcpy(ary2, t, t, RARRAY_CONST_PTR(ary2));
             t *= 2;
         }
         if (t < len) {
-            ary_memcpy(ary2, t, len-t, RARRAY_CONST_PTR_TRANSIENT(ary2));
+            ary_memcpy(ary2, t, len-t, RARRAY_CONST_PTR(ary2));
         }
     }
   out:
@@ -5203,17 +5254,18 @@ rb_ary_times(VALUE ary, VALUE times)
 
 /*
  *  call-seq:
- *    array.assoc(obj) -> found_array or nil
+ *    assoc(object) -> found_array or nil
  *
- *  Returns the first element in +self+ that is an \Array
- *  whose first element <tt>==</tt> +obj+:
+ *  Returns the first element +ele+ in +self+ such that +ele+ is an array
+ *  and <tt>ele[0] == object</tt>:
  *
  *    a = [{foo: 0}, [2, 4], [4, 5, 6], [4, 5]]
  *    a.assoc(4) # => [4, 5, 6]
  *
  *  Returns +nil+ if no such element is found.
  *
- *  Related: #rassoc.
+ *  Related: Array#rassoc;
+ *  see also {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 VALUE
@@ -5233,17 +5285,19 @@ rb_ary_assoc(VALUE ary, VALUE key)
 
 /*
  *  call-seq:
- *    array.rassoc(obj) -> found_array or nil
+ *    rassoc(object) -> found_array or nil
  *
- *  Returns the first element in +self+ that is an \Array
- *  whose second element <tt>==</tt> +obj+:
+ *  Returns the first element +ele+ in +self+ such that +ele+ is an array
+ *  and <tt>ele[1] == object</tt>:
  *
  *    a = [{foo: 0}, [2, 4], [4, 5, 6], [4, 5]]
  *    a.rassoc(4) # => [2, 4]
+ *    a.rassoc(5) # => [4, 5, 6]
  *
  *  Returns +nil+ if no such element is found.
  *
- *  Related: #assoc.
+ *  Related: Array#assoc;
+ *  see also {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 VALUE
@@ -5253,7 +5307,7 @@ rb_ary_rassoc(VALUE ary, VALUE value)
     VALUE v;
 
     for (i = 0; i < RARRAY_LEN(ary); ++i) {
-        v = RARRAY_AREF(ary, i);
+        v = rb_check_array_type(RARRAY_AREF(ary, i));
         if (RB_TYPE_P(v, T_ARRAY) &&
             RARRAY_LEN(v) > 1 &&
             rb_equal(RARRAY_AREF(v, 1), value))
@@ -5298,20 +5352,26 @@ recursive_equal(VALUE ary1, VALUE ary2, int recur)
 
 /*
  *  call-seq:
- *    array == other_array -> true or false
+ *    self == other_array -> true or false
  *
- *  Returns +true+ if both <tt>array.size == other_array.size</tt>
- *  and for each index +i+ in +array+, <tt>array[i] == other_array[i]</tt>:
+ *  Returns whether both:
  *
- *    a0 = [:foo, 'bar', 2]
- *    a1 = [:foo, 'bar', 2.0]
- *    a1 == a0 # => true
- *    [] == [] # => true
+ *  - +self+ and +other_array+ are the same size.
+ *  - Their corresponding elements are the same;
+ *    that is, for each index +i+ in <tt>(0...self.size)</tt>,
+ *    <tt>self[i] == other_array[i]</tt>.
  *
- *  Otherwise, returns +false+.
+ *  Examples:
+ *
+ *    [:foo, 'bar', 2] == [:foo, 'bar', 2]   # => true
+ *    [:foo, 'bar', 2] == [:foo, 'bar', 2.0] # => true
+ *    [:foo, 'bar', 2] == [:foo, 'bar']      # => false # Different sizes.
+ *    [:foo, 'bar', 2] == [:foo, 'bar', 3]   # => false # Different elements.
  *
  *  This method is different from method Array#eql?,
  *  which compares elements using <tt>Object#eql?</tt>.
+ *
+ *  Related: see {Methods for Comparing}[rdoc-ref:Array@Methods+for+Comparing].
  */
 
 static VALUE
@@ -5325,7 +5385,7 @@ rb_ary_equal(VALUE ary1, VALUE ary2)
         return rb_equal(ary2, ary1);
     }
     if (RARRAY_LEN(ary1) != RARRAY_LEN(ary2)) return Qfalse;
-    if (RARRAY_CONST_PTR_TRANSIENT(ary1) == RARRAY_CONST_PTR_TRANSIENT(ary2)) return Qtrue;
+    if (RARRAY_CONST_PTR(ary1) == RARRAY_CONST_PTR(ary2)) return Qtrue;
     return rb_exec_recursive_paired(recursive_equal, ary1, ary2, ary2);
 }
 
@@ -5344,10 +5404,10 @@ recursive_eql(VALUE ary1, VALUE ary2, int recur)
 
 /*
  *  call-seq:
- *    array.eql? other_array -> true or false
+ *    eql?(other_array) -> true or false
  *
  *  Returns +true+ if +self+ and +other_array+ are the same size,
- *  and if, for each index +i+ in +self+, <tt>self[i].eql? other_array[i]</tt>:
+ *  and if, for each index +i+ in +self+, <tt>self[i].eql?(other_array[i])</tt>:
  *
  *    a0 = [:foo, 'bar', 2]
  *    a1 = [:foo, 'bar', 2]
@@ -5357,6 +5417,8 @@ recursive_eql(VALUE ary1, VALUE ary2, int recur)
  *
  *  This method is different from method Array#==,
  *  which compares using method <tt>Object#==</tt>.
+ *
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -5365,49 +5427,71 @@ rb_ary_eql(VALUE ary1, VALUE ary2)
     if (ary1 == ary2) return Qtrue;
     if (!RB_TYPE_P(ary2, T_ARRAY)) return Qfalse;
     if (RARRAY_LEN(ary1) != RARRAY_LEN(ary2)) return Qfalse;
-    if (RARRAY_CONST_PTR_TRANSIENT(ary1) == RARRAY_CONST_PTR_TRANSIENT(ary2)) return Qtrue;
+    if (RARRAY_CONST_PTR(ary1) == RARRAY_CONST_PTR(ary2)) return Qtrue;
     return rb_exec_recursive_paired(recursive_eql, ary1, ary2, ary2);
 }
 
+static VALUE
+ary_hash_values(long len, const VALUE *elements, const VALUE ary)
+{
+    long i;
+    st_index_t h;
+    VALUE n;
+
+    h = rb_hash_start(len);
+    h = rb_hash_uint(h, (st_index_t)rb_ary_hash_values);
+    for (i=0; i<len; i++) {
+        n = rb_hash(elements[i]);
+        h = rb_hash_uint(h, NUM2LONG(n));
+        if (ary) {
+            len = RARRAY_LEN(ary);
+            elements = RARRAY_CONST_PTR(ary);
+        }
+    }
+    h = rb_hash_end(h);
+    return ST2FIX(h);
+}
+
+VALUE
+rb_ary_hash_values(long len, const VALUE *elements)
+{
+    return ary_hash_values(len, elements, 0);
+}
+
 /*
  *  call-seq:
- *    array.hash -> integer
+ *    hash -> integer
  *
  *  Returns the integer hash value for +self+.
  *
- *  Two arrays with the same content will have the same hash code (and will compare using eql?):
+ *  Two arrays with the same content will have the same hash value
+ *  (and will compare using eql?):
  *
- *    [0, 1, 2].hash == [0, 1, 2].hash # => true
- *    [0, 1, 2].hash == [0, 1, 3].hash # => false
+ *    ['a', 'b'].hash == ['a', 'b'].hash # => true
+ *    ['a', 'b'].hash == ['a', 'c'].hash # => false
+ *    ['a', 'b'].hash == ['a'].hash      # => false
  *
  */
 
 static VALUE
 rb_ary_hash(VALUE ary)
 {
-    long i;
-    st_index_t h;
-    VALUE n;
-
-    h = rb_hash_start(RARRAY_LEN(ary));
-    h = rb_hash_uint(h, (st_index_t)rb_ary_hash);
-    for (i=0; i<RARRAY_LEN(ary); i++) {
-        n = rb_hash(RARRAY_AREF(ary, i));
-        h = rb_hash_uint(h, NUM2LONG(n));
-    }
-    h = rb_hash_end(h);
-    return ST2FIX(h);
+    RBIMPL_ASSERT_OR_ASSUME(ary);
+    return ary_hash_values(RARRAY_LEN(ary), RARRAY_CONST_PTR(ary), ary);
 }
 
 /*
  *  call-seq:
- *    array.include?(obj) -> true or false
+ *    include?(object) -> true or false
  *
- *  Returns +true+ if for some index +i+ in +self+, <tt>obj == self[i]</tt>;
- *  otherwise +false+:
+ *  Returns whether for some element +element+ in +self+,
+ *  <tt>object == element</tt>:
  *
- *    [0, 1, 2].include?(2) # => true
- *    [0, 1, 2].include?(3) # => false
+ *    [0, 1, 2].include?(2)   # => true
+ *    [0, 1, 2].include?(2.0) # => true
+ *    [0, 1, 2].include?(2.1) # => false
+ *
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 VALUE
@@ -5462,33 +5546,40 @@ recursive_cmp(VALUE ary1, VALUE ary2, int recur)
 
 /*
  *  call-seq:
- *    array <=> other_array -> -1, 0, or 1
- *
- *  Returns -1, 0, or 1 as +self+ is less than, equal to, or greater than +other_array+.
- *  For each index +i+ in +self+, evaluates <tt>result = self[i] <=> other_array[i]</tt>.
+ *    self <=> other_array -> -1, 0, or 1
  *
- *  Returns -1 if any result is -1:
+ *  Returns -1, 0, or 1 as +self+ is determined
+ *  to be less than, equal to, or greater than +other_array+.
  *
- *    [0, 1, 2] <=> [0, 1, 3] # => -1
+ *  Iterates over each index +i+ in <tt>(0...self.size)</tt>:
  *
- *  Returns 1 if any result is 1:
+ *  - Computes <tt>result[i]</tt> as <tt>self[i] <=> other_array[i]</tt>.
+ *  - Immediately returns 1 if <tt>result[i]</tt> is 1:
  *
- *    [0, 1, 2] <=> [0, 1, 1] # => 1
+ *      [0, 1, 2] <=> [0, 0, 2] # => 1
  *
- *  When all results are zero:
+ *  - Immediately returns -1 if <tt>result[i]</tt> is -1:
  *
- *  - Returns -1 if +array+ is smaller than +other_array+:
+ *      [0, 1, 2] <=> [0, 2, 2] # => -1
  *
- *      [0, 1, 2] <=> [0, 1, 2, 3] # => -1
+ *  - Continues if <tt>result[i]</tt> is 0.
  *
- *  - Returns 1 if +array+ is larger than +other_array+:
+ *  When every +result+ is 0,
+ *  returns <tt>self.size <=> other_array.size</tt>
+ *  (see Integer#<=>):
  *
- *      [0, 1, 2] <=> [0, 1] # => 1
+ *    [0, 1, 2] <=> [0, 1]        # => 1
+ *    [0, 1, 2] <=> [0, 1, 2]     # => 0
+ *    [0, 1, 2] <=> [0, 1, 2, 3]  # => -1
  *
- *  - Returns 0 if +array+ and +other_array+ are the same size:
+ *  Note that when +other_array+ is larger than +self+,
+ *  its trailing elements do not affect the result:
  *
- *      [0, 1, 2] <=> [0, 1, 2] # => 0
+ *    [0, 1, 2] <=> [0, 1, 2, -3] # => -1
+ *    [0, 1, 2] <=> [0, 1, 2, 0]  # => -1
+ *    [0, 1, 2] <=> [0, 1, 2, 3]  # => -1
  *
+ *  Related: see {Methods for Comparing}[rdoc-ref:Array@Methods+for+Comparing].
  */
 
 VALUE
@@ -5501,7 +5592,7 @@ rb_ary_cmp(VALUE ary1, VALUE ary2)
     if (NIL_P(ary2)) return Qnil;
     if (ary1 == ary2) return INT2FIX(0);
     v = rb_exec_recursive_paired(recursive_cmp, ary1, ary2, ary2);
-    if (v != Qundef) return v;
+    if (!UNDEF_P(v)) return v;
     len = RARRAY_LEN(ary1) - RARRAY_LEN(ary2);
     if (len == 0) return INT2FIX(0);
     if (len > 0) return INT2FIX(1);
@@ -5556,34 +5647,25 @@ ary_make_hash_by(VALUE ary)
     return ary_add_hash_by(hash, ary);
 }
 
-static inline void
-ary_recycle_hash(VALUE hash)
-{
-    assert(RBASIC_CLASS(hash) == 0);
-    if (RHASH_ST_TABLE_P(hash)) {
-        st_table *tbl = RHASH_ST_TABLE(hash);
-        st_free_table(tbl);
-        RHASH_ST_CLEAR(hash);
-    }
-}
-
 /*
  *  call-seq:
- *    array - other_array -> new_array
+ *    self - other_array -> new_array
+ *
+ *  Returns a new array containing only those elements of +self+
+ *  that are not found in +other_array+;
+ *  the order from +self+ is preserved:
  *
- *  Returns a new \Array containing only those elements from +array+
- *  that are not found in \Array +other_array+;
- *  items are compared using <tt>eql?</tt>;
- *  the order from +array+ is preserved:
+ *    [0, 1, 1, 2, 1, 1, 3, 1, 1] - [1]             # => [0, 2, 3]
+ *    [0, 1, 1, 2, 1, 1, 3, 1, 1] - [3, 2, 0, :foo] # => [1, 1, 1, 1, 1, 1]
+ *    [0, 1, 2] - [:foo]                            # => [0, 1, 2]
  *
- *    [0, 1, 1, 2, 1, 1, 3, 1, 1] - [1] # => [0, 2, 3]
- *    [0, 1, 2, 3] - [3, 0] # => [1, 2]
- *    [0, 1, 2] - [4] # => [0, 1, 2]
+ *  Element are compared using method <tt>#eql?</tt>
+ *  (as defined in each element of +self+).
  *
- *  Related: Array#difference.
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
-static VALUE
+VALUE
 rb_ary_diff(VALUE ary1, VALUE ary2)
 {
     VALUE ary3;
@@ -5608,25 +5690,27 @@ rb_ary_diff(VALUE ary1, VALUE ary2)
         if (rb_hash_stlike_lookup(hash, RARRAY_AREF(ary1, i), NULL)) continue;
         rb_ary_push(ary3, rb_ary_elt(ary1, i));
     }
-    ary_recycle_hash(hash);
+
     return ary3;
 }
 
 /*
  *  call-seq:
- *    array.difference(*other_arrays) -> new_array
+ *    difference(*other_arrays = []) -> new_array
  *
- *  Returns a new \Array containing only those elements from +self+
- *  that are not found in any of the Arrays +other_arrays+;
+ *  Returns a new array containing only those elements from +self+
+ *  that are not found in any of the given +other_arrays+;
  *  items are compared using <tt>eql?</tt>;  order from +self+ is preserved:
  *
  *    [0, 1, 1, 2, 1, 1, 3, 1, 1].difference([1]) # => [0, 2, 3]
- *    [0, 1, 2, 3].difference([3, 0], [1, 3]) # => [2]
- *    [0, 1, 2].difference([4]) # => [0, 1, 2]
+ *    [0, 1, 2, 3].difference([3, 0], [1, 3])     # => [2]
+ *    [0, 1, 2].difference([4])                   # => [0, 1, 2]
+ *    [0, 1, 2].difference                        # => [0, 1, 2]
  *
- *  Returns a copy of +self+ if no arguments given.
+ *  Returns a copy of +self+ if no arguments are given.
  *
- *  Related: Array#-.
+ *  Related: Array#-;
+ *  see also {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
 static VALUE
@@ -5650,7 +5734,7 @@ rb_ary_difference_multi(int argc, VALUE *argv, VALUE ary)
         VALUE elt = rb_ary_elt(ary, i);
         for (j = 0; j < argc; j++) {
             if (is_hash[j]) {
-                if (rb_hash_stlike_lookup(argv[j], RARRAY_AREF(ary, i), NULL))
+                if (rb_hash_stlike_lookup(argv[j], elt, NULL))
                     break;
             }
             else {
@@ -5668,19 +5752,25 @@ rb_ary_difference_multi(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array & other_array -> new_array
+ *    self & other_array -> new_array
  *
- *  Returns a new \Array containing each element found in both +array+ and \Array +other_array+;
- *  duplicates are omitted; items are compared using <tt>eql?</tt>:
+ *  Returns a new array containing the _intersection_ of +self+ and +other_array+;
+ *  that is, containing those elements found in both +self+ and +other_array+:
  *
  *    [0, 1, 2, 3] & [1, 2] # => [1, 2]
- *    [0, 1, 0, 1] & [0, 1] # => [0, 1]
  *
- *  Preserves order from +array+:
+ *  Omits duplicates:
+ *
+ *    [0, 1, 1, 0] & [0, 1] # => [0, 1]
+ *
+ *  Preserves order from +self+:
  *
  *    [0, 1, 2] & [3, 2, 1, 0] # => [0, 1, 2]
  *
- *  Related: Array#intersection.
+ *  Identifies common elements using method <tt>#eql?</tt>
+ *  (as defined in each element of +self+).
+ *
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
 
@@ -5714,29 +5804,29 @@ rb_ary_and(VALUE ary1, VALUE ary2)
             rb_ary_push(ary3, v);
         }
     }
-    ary_recycle_hash(hash);
 
     return ary3;
 }
 
 /*
  *  call-seq:
- *    array.intersection(*other_arrays) -> new_array
+ *    intersection(*other_arrays) -> new_array
  *
- *  Returns a new \Array containing each element found both in +self+
- *  and in all of the given Arrays +other_arrays+;
- *  duplicates are omitted; items are compared using <tt>eql?</tt>:
+ *  Returns a new array containing each element in +self+ that is +#eql?+
+ *  to at least one element in each of the given +other_arrays+;
+ *  duplicates are omitted:
  *
- *    [0, 1, 2, 3].intersection([0, 1, 2], [0, 1, 3]) # => [0, 1]
  *    [0, 0, 1, 1, 2, 3].intersection([0, 1, 2], [0, 1, 3]) # => [0, 1]
  *
- *  Preserves order from +self+:
+ *  Each element must correctly implement method <tt>#hash</tt>.
+ *
+ *  Order from +self+ is preserved:
  *
  *    [0, 1, 2].intersection([2, 1, 0]) # => [0, 1, 2]
  *
- *  Returns a copy of +self+ if no arguments given.
+ *  Returns a copy of +self+ if no arguments are given.
  *
- *  Related: Array#&.
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
 static VALUE
@@ -5785,9 +5875,9 @@ rb_ary_union_hash(VALUE hash, VALUE ary2)
 
 /*
  *  call-seq:
- *    array | other_array -> new_array
+ *    self | other_array -> new_array
  *
- *  Returns the union of +array+ and \Array +other_array+;
+ *  Returns the union of +self+ and +other_array+;
  *  duplicates are removed; order is preserved;
  *  items are compared using <tt>eql?</tt>:
  *
@@ -5795,17 +5885,17 @@ rb_ary_union_hash(VALUE hash, VALUE ary2)
  *    [0, 1, 1] | [2, 2, 3] # => [0, 1, 2, 3]
  *    [0, 1, 2] | [3, 2, 1, 0] # => [0, 1, 2, 3]
  *
- *  Related: Array#union.
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
 static VALUE
 rb_ary_or(VALUE ary1, VALUE ary2)
 {
-    VALUE hash, ary3;
+    VALUE hash;
 
     ary2 = to_ary(ary2);
     if (RARRAY_LEN(ary1) + RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) {
-        ary3 = rb_ary_new();
+        VALUE ary3 = rb_ary_new();
         rb_ary_union(ary3, ary1);
         rb_ary_union(ary3, ary2);
         return ary3;
@@ -5814,25 +5904,30 @@ rb_ary_or(VALUE ary1, VALUE ary2)
     hash = ary_make_hash(ary1);
     rb_ary_union_hash(hash, ary2);
 
-    ary3 = rb_hash_values(hash);
-    ary_recycle_hash(hash);
-    return ary3;
+    return rb_hash_values(hash);
 }
 
 /*
  *  call-seq:
- *    array.union(*other_arrays) -> new_array
+ *    union(*other_arrays) -> new_array
  *
- *  Returns a new \Array that is the union of +self+ and all given Arrays +other_arrays+;
- *  duplicates are removed;  order is preserved;  items are compared using <tt>eql?</tt>:
+ *  Returns a new array that is the union of the elements of +self+
+ *  and all given arrays +other_arrays+;
+ *  items are compared using <tt>eql?</tt>:
  *
  *    [0, 1, 2, 3].union([4, 5], [6, 7]) # => [0, 1, 2, 3, 4, 5, 6, 7]
+ *
+ *  Removes duplicates (preserving the first found):
+ *
  *    [0, 1, 1].union([2, 1], [3, 1]) # => [0, 1, 2, 3]
- *    [0, 1, 2, 3].union([3, 2], [1, 0]) # => [0, 1, 2, 3]
  *
- *  Returns a copy of +self+ if no arguments given.
+ *  Preserves order (preserving the position of the first found):
+ *
+ *    [3, 2, 1, 0].union([5, 3], [4, 2]) # => [3, 2, 1, 0, 5, 4]
  *
- *  Related: Array#|.
+ *  With no arguments given, returns a copy of +self+.
+ *
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
 static VALUE
@@ -5840,7 +5935,7 @@ rb_ary_union_multi(int argc, VALUE *argv, VALUE ary)
 {
     int i;
     long sum;
-    VALUE hash, ary_union;
+    VALUE hash;
 
     sum = RARRAY_LEN(ary);
     for (i = 0; i < argc; i++) {
@@ -5849,7 +5944,7 @@ rb_ary_union_multi(int argc, VALUE *argv, VALUE ary)
     }
 
     if (sum <= SMALL_ARRAY_LEN) {
-        ary_union = rb_ary_new();
+        VALUE ary_union = rb_ary_new();
 
         rb_ary_union(ary_union, ary);
         for (i = 0; i < argc; i++) rb_ary_union(ary_union, argv[i]);
@@ -5860,24 +5955,21 @@ rb_ary_union_multi(int argc, VALUE *argv, VALUE ary)
     hash = ary_make_hash(ary);
     for (i = 0; i < argc; i++) rb_ary_union_hash(hash, argv[i]);
 
-    ary_union = rb_hash_values(hash);
-    ary_recycle_hash(hash);
-    return ary_union;
+    return rb_hash_values(hash);
 }
 
 /*
  *  call-seq:
- *     ary.intersect?(other_ary)   -> true or false
+ *    intersect?(other_array) -> true or false
+ *
+ *  Returns whether +other_array+ has at least one element that is +#eql?+ to some element of +self+:
  *
- *  Returns +true+ if the array and +other_ary+ have at least one element in
- *  common, otherwise returns +false+:
+ *    [1, 2, 3].intersect?([3, 4, 5]) # => true
+ *    [1, 2, 3].intersect?([4, 5, 6]) # => false
  *
- *     a = [ 1, 2, 3 ]
- *     b = [ 3, 4, 5 ]
- *     c = [ 5, 6, 7 ]
- *     a.intersect?(b)   #=> true
- *     a.intersect?(c)   #=> false
+ *  Each element must correctly implement method <tt>#hash</tt>.
  *
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -5916,7 +6008,6 @@ rb_ary_intersect_p(VALUE ary1, VALUE ary2)
             break;
         }
     }
-    ary_recycle_hash(hash);
 
     return result;
 }
@@ -6012,47 +6103,55 @@ ary_max_opt_string(VALUE ary, long i, VALUE vmax)
 
 /*
  *  call-seq:
- *    array.max -> element
- *    array.max {|a, b| ... } -> element
- *    array.max(n) -> new_array
- *    array.max(n) {|a, b| ... } -> new_array
+ *    max -> element
+ *    max(count) -> new_array
+ *    max {|a, b| ... } -> element
+ *    max(count) {|a, b| ... } -> new_array
  *
  *  Returns one of the following:
  *
  *  - The maximum-valued element from +self+.
- *  - A new \Array of maximum-valued elements selected from +self+.
+ *  - A new array of maximum-valued elements from +self+.
  *
- *  When no block is given, each element in +self+ must respond to method <tt><=></tt>
- *  with an \Integer.
+ *  Does not modify +self+.
+ *
+ *  With no block given, each element in +self+ must respond to method <tt>#<=></tt>
+ *  with a numeric.
  *
  *  With no argument and no block, returns the element in +self+
- *  having the maximum value per method <tt><=></tt>:
+ *  having the maximum value per method <tt>#<=></tt>:
  *
- *    [0, 1, 2].max # => 2
+ *    [1, 0, 3, 2].max # => 3
  *
- *  With an argument \Integer +n+ and no block, returns a new \Array with at most +n+ elements,
- *  in descending order per method <tt><=></tt>:
+ *  With non-negative numeric argument +count+ and no block,
+ *  returns a new array with at most +count+ elements,
+ *  in descending order, per method <tt>#<=></tt>:
  *
- *    [0, 1, 2, 3].max(3) # => [3, 2, 1]
- *    [0, 1, 2, 3].max(6) # => [3, 2, 1, 0]
+ *    [1, 0, 3, 2].max(3)   # => [3, 2, 1]
+ *    [1, 0, 3, 2].max(3.0) # => [3, 2, 1]
+ *    [1, 0, 3, 2].max(9)   # => [3, 2, 1, 0]
+ *    [1, 0, 3, 2].max(0)   # => []
  *
- *  When a block is given, the block must return an \Integer.
+ *  With a block given, the block must return a numeric.
  *
- *  With a block and no argument, calls the block <tt>self.size-1</tt> times to compare elements;
+ *  With a block and no argument, calls the block <tt>self.size - 1</tt> times to compare elements;
  *  returns the element having the maximum value per the block:
  *
- *    ['0', '00', '000'].max {|a, b| a.size <=> b.size } # => "000"
+ *    ['0', '', '000', '00'].max {|a, b| a.size <=> b.size }
+ *    # => "000"
  *
- *  With an argument +n+ and a block, returns a new \Array with at most +n+ elements,
- *  in descending order per the block:
+ *  With non-negative numeric argument +count+ and a block,
+ *  returns a new array with at most +count+ elements,
+ *  in descending order, per the block:
  *
- *    ['0', '00', '000'].max(2) {|a, b| a.size <=> b.size } # => ["000", "00"]
+ *    ['0', '', '000', '00'].max(2) {|a, b| a.size <=> b.size }
+ *    # => ["000", "00"]
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 static VALUE
 rb_ary_max(int argc, VALUE *argv, VALUE ary)
 {
-    struct cmp_opt_data cmp_opt = { 0, 0 };
     VALUE result = Qundef, v;
     VALUE num;
     long i;
@@ -6064,7 +6163,7 @@ rb_ary_max(int argc, VALUE *argv, VALUE ary)
     if (rb_block_given_p()) {
         for (i = 0; i < RARRAY_LEN(ary); i++) {
            v = RARRAY_AREF(ary, i);
-           if (result == Qundef || rb_cmpint(rb_yield_values(2, v, result), v, result) > 0) {
+           if (UNDEF_P(result) || rb_cmpint(rb_yield_values(2, v, result), v, result) > 0) {
                result = v;
            }
         }
@@ -6072,13 +6171,13 @@ rb_ary_max(int argc, VALUE *argv, VALUE ary)
     else if (n > 0) {
         result = RARRAY_AREF(ary, 0);
         if (n > 1) {
-            if (FIXNUM_P(result) && CMP_OPTIMIZABLE(cmp_opt, Integer)) {
+            if (FIXNUM_P(result) && CMP_OPTIMIZABLE(INTEGER)) {
                 return ary_max_opt_fixnum(ary, 1, result);
             }
-            else if (STRING_P(result) && CMP_OPTIMIZABLE(cmp_opt, String)) {
+            else if (STRING_P(result) && CMP_OPTIMIZABLE(STRING)) {
                 return ary_max_opt_string(ary, 1, result);
             }
-            else if (RB_FLOAT_TYPE_P(result) && CMP_OPTIMIZABLE(cmp_opt, Float)) {
+            else if (RB_FLOAT_TYPE_P(result) && CMP_OPTIMIZABLE(FLOAT)) {
                 return ary_max_opt_float(ary, 1, result);
             }
             else {
@@ -6086,7 +6185,7 @@ rb_ary_max(int argc, VALUE *argv, VALUE ary)
             }
         }
     }
-    if (result == Qundef) return Qnil;
+    if (UNDEF_P(result)) return Qnil;
     return result;
 }
 
@@ -6181,47 +6280,55 @@ ary_min_opt_string(VALUE ary, long i, VALUE vmin)
 
 /*
  *  call-seq:
- *    array.min -> element
- *    array.min { |a, b| ... } -> element
- *    array.min(n) -> new_array
- *    array.min(n) { |a, b| ... } -> new_array
+ *    min -> element
+ *    min(count) -> new_array
+ *    min {|a, b| ... } -> element
+ *    min(count) {|a, b| ... } -> new_array
  *
  *  Returns one of the following:
  *
  *  - The minimum-valued element from +self+.
- *  - A new \Array of minimum-valued elements selected from +self+.
+ *  - A new array of minimum-valued elements from +self+.
+ *
+ *  Does not modify +self+.
  *
- *  When no block is given, each element in +self+ must respond to method <tt><=></tt>
- *  with an \Integer.
+ *  With no block given, each element in +self+ must respond to method <tt>#<=></tt>
+ *  with a numeric.
  *
  *  With no argument and no block, returns the element in +self+
- *  having the minimum value per method <tt><=></tt>:
+ *  having the minimum value per method <tt>#<=></tt>:
  *
- *    [0, 1, 2].min # => 0
+ *    [1, 0, 3, 2].min # => 0
  *
- *  With \Integer argument +n+ and no block, returns a new \Array with at most +n+ elements,
- *  in ascending order per method <tt><=></tt>:
+ *  With non-negative numeric argument +count+ and no block,
+ *  returns a new array with at most +count+ elements,
+ *  in ascending order, per method <tt>#<=></tt>:
  *
- *    [0, 1, 2, 3].min(3) # => [0, 1, 2]
- *    [0, 1, 2, 3].min(6) # => [0, 1, 2, 3]
+ *    [1, 0, 3, 2].min(3)   # => [0, 1, 2]
+ *    [1, 0, 3, 2].min(3.0) # => [0, 1, 2]
+ *    [1, 0, 3, 2].min(9)   # => [0, 1, 2, 3]
+ *    [1, 0, 3, 2].min(0)   # => []
  *
- *  When a block is given, the block must return an Integer.
+ *  With a block given, the block must return a numeric.
  *
- *  With a block and no argument, calls the block <tt>self.size-1</tt> times to compare elements;
+ *  With a block and no argument, calls the block <tt>self.size - 1</tt> times to compare elements;
  *  returns the element having the minimum value per the block:
  *
- *    ['0', '00', '000'].min { |a, b| a.size <=> b.size } # => "0"
+ *    ['0', '', '000', '00'].min {|a, b| a.size <=> b.size }
+ *    # => ""
  *
- *  With an argument +n+ and a block, returns a new \Array with at most +n+ elements,
- *  in ascending order per the block:
+ *  With non-negative numeric argument +count+ and a block,
+ *  returns a new array with at most +count+ elements,
+ *  in ascending order, per the block:
  *
- *    ['0', '00', '000'].min(2) {|a, b| a.size <=> b.size } # => ["0", "00"]
+ *    ['0', '', '000', '00'].min(2) {|a, b| a.size <=> b.size }
+ *    # => ["", "0"]
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 static VALUE
 rb_ary_min(int argc, VALUE *argv, VALUE ary)
 {
-    struct cmp_opt_data cmp_opt = { 0, 0 };
     VALUE result = Qundef, v;
     VALUE num;
     long i;
@@ -6233,7 +6340,7 @@ rb_ary_min(int argc, VALUE *argv, VALUE ary)
     if (rb_block_given_p()) {
         for (i = 0; i < RARRAY_LEN(ary); i++) {
            v = RARRAY_AREF(ary, i);
-           if (result == Qundef || rb_cmpint(rb_yield_values(2, v, result), v, result) < 0) {
+           if (UNDEF_P(result) || rb_cmpint(rb_yield_values(2, v, result), v, result) < 0) {
                result = v;
            }
         }
@@ -6241,13 +6348,13 @@ rb_ary_min(int argc, VALUE *argv, VALUE ary)
     else if (n > 0) {
         result = RARRAY_AREF(ary, 0);
         if (n > 1) {
-            if (FIXNUM_P(result) && CMP_OPTIMIZABLE(cmp_opt, Integer)) {
+            if (FIXNUM_P(result) && CMP_OPTIMIZABLE(INTEGER)) {
                 return ary_min_opt_fixnum(ary, 1, result);
             }
-            else if (STRING_P(result) && CMP_OPTIMIZABLE(cmp_opt, String)) {
+            else if (STRING_P(result) && CMP_OPTIMIZABLE(STRING)) {
                 return ary_min_opt_string(ary, 1, result);
             }
-            else if (RB_FLOAT_TYPE_P(result) && CMP_OPTIMIZABLE(cmp_opt, Float)) {
+            else if (RB_FLOAT_TYPE_P(result) && CMP_OPTIMIZABLE(FLOAT)) {
                 return ary_min_opt_float(ary, 1, result);
             }
             else {
@@ -6255,32 +6362,31 @@ rb_ary_min(int argc, VALUE *argv, VALUE ary)
             }
         }
     }
-    if (result == Qundef) return Qnil;
+    if (UNDEF_P(result)) return Qnil;
     return result;
 }
 
 /*
  *  call-seq:
- *    array.minmax -> [min_val, max_val]
- *    array.minmax {|a, b| ... } -> [min_val, max_val]
+ *    minmax -> array
+ *    minmax {|a, b| ... } -> array
  *
- *  Returns a new 2-element \Array containing the minimum and maximum values
- *  from +self+, either per method <tt><=></tt> or per a given block:.
+ *  Returns a 2-element array containing the minimum-valued and maximum-valued
+ *  elements from +self+;
+ *  does not modify +self+.
  *
- *  When no block is given, each element in +self+ must respond to method <tt><=></tt>
- *  with an \Integer;
- *  returns a new 2-element \Array containing the minimum and maximum values
- *  from +self+, per method <tt><=></tt>:
+ *  With no block given, the minimum and maximum values are determined using method <tt>#<=></tt>:
  *
- *    [0, 1, 2].minmax # => [0, 2]
+ *    [1, 0, 3, 2].minmax # => [0, 3]
  *
- *  When a block is given, the block must return an \Integer;
- *  the block is called <tt>self.size-1</tt> times to compare elements;
- *  returns a new 2-element \Array containing the minimum and maximum values
- *  from +self+, per the block:
+ *  With a block given, the block must return a numeric;
+ *  the block is called <tt>self.size - 1</tt> times to compare elements;
+ *  returns the elements having the minimum and maximum values per the block:
  *
- *    ['0', '00', '000'].minmax {|a, b| a.size <=> b.size } # => ["0", "000"]
+ *    ['0', '', '000', '00'].minmax {|a, b| a.size <=> b.size }
+ *    # => ["", "000"]
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 static VALUE
 rb_ary_minmax(VALUE ary)
@@ -6300,32 +6406,30 @@ push_value(st_data_t key, st_data_t val, st_data_t ary)
 
 /*
  *  call-seq:
- *    array.uniq! -> self or nil
- *    array.uniq! {|element| ... } -> self or nil
+ *    uniq! -> self or nil
+ *    uniq! {|element| ... } -> self or nil
  *
  *  Removes duplicate elements from +self+, the first occurrence always being retained;
  *  returns +self+ if any elements removed, +nil+ otherwise.
  *
  *  With no block given, identifies and removes elements using method <tt>eql?</tt>
- *  to compare.
- *
- *  Returns +self+ if any elements removed:
+ *  to compare elements:
  *
  *    a = [0, 0, 1, 1, 2, 2]
  *    a.uniq! # => [0, 1, 2]
- *
- *  Returns +nil+ if no elements removed.
+ *    a.uniq! # => nil
  *
  *  With a block given, calls the block for each element;
- *  identifies (using method <tt>eql?</tt>) and removes
- *  elements for which the block returns duplicate values.
- *
- *  Returns +self+ if any elements removed:
+ *  identifies and omits "duplicate" elements using method <tt>eql?</tt>
+ *  to compare <i>block return values</i>;
+ *  that is, an element is a duplicate if its block return value
+ *  is the same as that of a previous element:
  *
  *    a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb']
- *    a.uniq! {|element| element.size } # => ['a', 'aa', 'aaa']
+ *    a.uniq! {|element| element.size } # => ["a", "aa", "aaa"]
+ *    a.uniq! {|element| element.size } # => nil
  *
- *  Returns +nil+ if no elements removed.
+ *  Related: see {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 static VALUE
 rb_ary_uniq_bang(VALUE ary)
@@ -6347,38 +6451,40 @@ rb_ary_uniq_bang(VALUE ary)
     }
     rb_ary_modify_check(ary);
     ARY_SET_LEN(ary, 0);
-    if (ARY_SHARED_P(ary) && !ARY_EMBED_P(ary)) {
+    if (ARY_SHARED_P(ary)) {
         rb_ary_unshare(ary);
         FL_SET_EMBED(ary);
     }
     ary_resize_capa(ary, hash_size);
     rb_hash_foreach(hash, push_value, ary);
-    ary_recycle_hash(hash);
 
     return ary;
 }
 
 /*
  *  call-seq:
- *    array.uniq -> new_array
- *    array.uniq {|element| ... } -> new_array
+ *    uniq -> new_array
+ *    uniq {|element| ... } -> new_array
  *
- *  Returns a new \Array containing those elements from +self+ that are not duplicates,
+ *  Returns a new array containing those elements from +self+ that are not duplicates,
  *  the first occurrence always being retained.
  *
- *  With no block given, identifies and omits duplicates using method <tt>eql?</tt>
- *  to compare:
+ *  With no block given, identifies and omits duplicate elements using method <tt>eql?</tt>
+ *  to compare elements:
  *
  *    a = [0, 0, 1, 1, 2, 2]
  *    a.uniq # => [0, 1, 2]
  *
  *  With a block given, calls the block for each element;
- *  identifies (using method <tt>eql?</tt>) and omits duplicate values,
- *  that is, those elements for which the block returns the same value:
+ *  identifies and omits "duplicate" elements using method <tt>eql?</tt>
+ *  to compare <i>block return values</i>;
+ *  that is, an element is a duplicate if its block return value
+ *  is the same as that of a previous element:
  *
  *    a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb']
  *    a.uniq {|element| element.size } # => ["a", "aa", "aaa"]
  *
+ *  Related: {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -6398,20 +6504,24 @@ rb_ary_uniq(VALUE ary)
         hash = ary_make_hash(ary);
         uniq = rb_hash_values(hash);
     }
-    if (hash) {
-        ary_recycle_hash(hash);
-    }
 
     return uniq;
 }
 
 /*
  *  call-seq:
- *    array.compact! -> self or nil
+ *    compact! -> self or nil
+ *
+ *  Removes all +nil+ elements from +self+;
+ *  Returns +self+ if any elements are removed, +nil+ otherwise:
  *
- *  Removes all +nil+ elements from +self+.
+ *    a = [nil, 0, nil, false, nil, '', nil, [], nil, {}]
+ *    a.compact! # => [0, false, "", [], {}]
+ *    a          # => [0, false, "", [], {}]
+ *    a.compact! # => nil
  *
- *  Returns +self+ if any elements removed, otherwise +nil+.
+ *  Related: Array#compact;
+ *  see also {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 static VALUE
@@ -6421,14 +6531,14 @@ rb_ary_compact_bang(VALUE ary)
     long n;
 
     rb_ary_modify(ary);
-    p = t = (VALUE *)RARRAY_CONST_PTR_TRANSIENT(ary); /* WB: no new reference */
+    p = t = (VALUE *)RARRAY_CONST_PTR(ary); /* WB: no new reference */
     end = p + RARRAY_LEN(ary);
 
     while (t < end) {
         if (NIL_P(*t)) t++;
         else *p++ = *t++;
     }
-    n = p - RARRAY_CONST_PTR_TRANSIENT(ary);
+    n = p - RARRAY_CONST_PTR(ary);
     if (RARRAY_LEN(ary) == n) {
         return Qnil;
     }
@@ -6439,12 +6549,16 @@ rb_ary_compact_bang(VALUE ary)
 
 /*
  *  call-seq:
- *    array.compact -> new_array
+ *    compact -> new_array
  *
- *  Returns a new \Array containing all non-+nil+ elements from +self+:
+ *  Returns a new array containing only the non-+nil+ elements from +self+;
+ *  element order is preserved:
  *
- *    a = [nil, 0, nil, 1, nil, 2, nil]
- *    a.compact # => [0, 1, 2]
+ *    a = [nil, 0, nil, false, nil, '', nil, [], nil, {}]
+ *    a.compact # => [0, false, "", [], {}]
+ *
+ *  Related: Array#compact!;
+ *  see also {Methods for Deleting}[rdoc-ref:Array@Methods+for+Deleting].
  */
 
 static VALUE
@@ -6457,29 +6571,29 @@ rb_ary_compact(VALUE ary)
 
 /*
  *  call-seq:
- *    array.count -> an_integer
- *    array.count(obj) -> an_integer
- *    array.count {|element| ... } -> an_integer
+ *    count -> integer
+ *    count(object) -> integer
+ *    count {|element| ... } -> integer
  *
  *  Returns a count of specified elements.
  *
  *  With no argument and no block, returns the count of all elements:
  *
- *    [0, 1, 2].count # => 3
- *    [].count # => 0
+ *    [0, :one, 'two', 3, 3.0].count # => 5
  *
- *  With argument +obj+, returns the count of elements <tt>==</tt> to +obj+:
+ *  With argument +object+ given, returns the count of elements <tt>==</tt> to +object+:
  *
- *    [0, 1, 2, 0.0].count(0) # => 2
- *    [0, 1, 2].count(3) # => 0
+ *    [0, :one, 'two', 3, 3.0].count(3) # => 2
  *
  *  With no argument and a block given, calls the block with each element;
  *  returns the count of elements for which the block returns a truthy value:
  *
- *    [0, 1, 2, 3].count {|element| element > 1} # => 2
+ *    [0, 1, 2, 3].count {|element| element > 1 } # => 2
+ *
+ *  With argument +object+ and a block given, issues a warning, ignores the block,
+ *  and returns the count of elements <tt>==</tt> to +object+.
  *
- *  With argument +obj+ and a block given, issues a warning, ignores the block,
- *  and returns the count of elements <tt>==</tt> to +obj+.
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -6516,9 +6630,8 @@ static VALUE
 flatten(VALUE ary, int level)
 {
     long i;
-    VALUE stack, result, tmp = 0, elt, vmemo;
-    st_table *memo = 0;
-    st_data_t id;
+    VALUE stack, result, tmp = 0, elt;
+    VALUE memo = Qfalse;
 
     for (i = 0; i < RARRAY_LEN(ary); i++) {
         elt = RARRAY_AREF(ary, i);
@@ -6532,7 +6645,7 @@ flatten(VALUE ary, int level)
     }
 
     result = ary_new(0, RARRAY_LEN(ary));
-    ary_memcpy(result, 0, i, RARRAY_CONST_PTR_TRANSIENT(ary));
+    ary_memcpy(result, 0, i, RARRAY_CONST_PTR(ary));
     ARY_SET_LEN(result, i);
 
     stack = ary_new(0, ARY_DEFAULT_SIZE);
@@ -6540,12 +6653,9 @@ flatten(VALUE ary, int level)
     rb_ary_push(stack, LONG2NUM(i + 1));
 
     if (level < 0) {
-        vmemo = rb_hash_new();
-        RBASIC_CLEAR_CLASS(vmemo);
-        memo = st_init_numtable();
-        rb_hash_st_table_set(vmemo, memo);
-        st_insert(memo, (st_data_t)ary, (st_data_t)Qtrue);
-        st_insert(memo, (st_data_t)tmp, (st_data_t)Qtrue);
+        memo = rb_obj_hide(rb_ident_hash_new());
+        rb_hash_aset(memo, ary, Qtrue);
+        rb_hash_aset(memo, tmp, Qtrue);
     }
 
     ary = tmp;
@@ -6560,9 +6670,8 @@ flatten(VALUE ary, int level)
             }
             tmp = rb_check_array_type(elt);
             if (RBASIC(result)->klass) {
-                if (memo) {
-                    RB_GC_GUARD(vmemo);
-                    st_clear(memo);
+                if (RTEST(memo)) {
+                    rb_hash_clear(memo);
                 }
                 rb_raise(rb_eRuntimeError, "flatten reentered");
             }
@@ -6571,12 +6680,11 @@ flatten(VALUE ary, int level)
             }
             else {
                 if (memo) {
-                    id = (st_data_t)tmp;
-                    if (st_is_member(memo, id)) {
-                        st_clear(memo);
+                    if (rb_hash_aref(memo, tmp) == Qtrue) {
+                        rb_hash_clear(memo);
                         rb_raise(rb_eArgError, "tried to flatten recursive array");
                     }
-                    st_insert(memo, id, (st_data_t)Qtrue);
+                    rb_hash_aset(memo, tmp, Qtrue);
                 }
                 rb_ary_push(stack, ary);
                 rb_ary_push(stack, LONG2NUM(i));
@@ -6588,8 +6696,7 @@ flatten(VALUE ary, int level)
             break;
         }
         if (memo) {
-            id = (st_data_t)ary;
-            st_delete(memo, &id, 0);
+            rb_hash_delete(memo, ary);
         }
         tmp = rb_ary_pop(stack);
         i = NUM2LONG(tmp);
@@ -6597,7 +6704,7 @@ flatten(VALUE ary, int level)
     }
 
     if (memo) {
-        st_clear(memo);
+        rb_hash_clear(memo);
     }
 
     RBASIC_SET_CLASS(result, rb_cArray);
@@ -6606,33 +6713,37 @@ flatten(VALUE ary, int level)
 
 /*
  *  call-seq:
- *    array.flatten! -> self or nil
- *    array.flatten!(level) -> self or nil
+ *    flatten!(depth = nil) -> self or nil
  *
- *  Replaces each nested \Array in +self+ with the elements from that \Array;
- *  returns +self+ if any changes, +nil+ otherwise.
+ *  Returns +self+ as a recursively flattening of +self+ to +depth+ levels of recursion;
+ *  +depth+ must be an
+ *  {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects],
+ *  or +nil+.
+ *  At each level of recursion:
  *
- *  With non-negative \Integer argument +level+, flattens recursively through +level+ levels:
+ *  - Each element that is an array is "flattened"
+ *    (that is, replaced by its individual array elements).
+ *  - Each element that is not an array is unchanged
+ *    (even if the element is an object that has instance method +flatten+).
  *
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten!(1) # => [0, 1, [2, 3], 4, 5]
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten!(2) # => [0, 1, 2, 3, 4, 5]
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten!(3) # => [0, 1, 2, 3, 4, 5]
- *    [0, 1, 2].flatten!(1) # => nil
+ *  Returns +nil+ if no elements were flattened.
  *
- *  With no argument, a +nil+ argument, or with negative argument +level+, flattens all levels:
+ *  With non-negative integer argument +depth+, flattens recursively through +depth+ levels:
  *
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten! # => [0, 1, 2, 3, 4, 5]
- *    [0, 1, 2].flatten! # => nil
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten!(-1) # => [0, 1, 2, 3, 4, 5]
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten!(-2) # => [0, 1, 2, 3, 4, 5]
- *    [0, 1, 2].flatten!(-1) # => nil
+ *    a = [ 0, [ 1, [2, 3], 4 ], 5, {foo: 0}, Set.new([6, 7]) ]
+ *    a                   # => [0, [1, [2, 3], 4], 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.dup.flatten!(1)   # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.dup.flatten!(1.1) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.dup.flatten!(2)   # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.dup.flatten!(3)   # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
  *
+ *  With +nil+ or negative argument +depth+, flattens all levels:
+ *
+ *    a.dup.flatten!     # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.dup.flatten!(-1) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *
+ *  Related: Array#flatten;
+ *  see also {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
  */
 
 static VALUE
@@ -6650,7 +6761,7 @@ rb_ary_flatten_bang(int argc, VALUE *argv, VALUE ary)
     if (result == ary) {
         return Qnil;
     }
-    if (!(mod = ARY_EMBED_P(result))) rb_obj_freeze(result);
+    if (!(mod = ARY_EMBED_P(result))) rb_ary_freeze(result);
     rb_ary_replace(ary, result);
     if (mod) ARY_SET_EMBED_LEN(result, 0);
 
@@ -6659,35 +6770,37 @@ rb_ary_flatten_bang(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.flatten -> new_array
- *    array.flatten(level) -> new_array
- *
- *  Returns a new \Array that is a recursive flattening of +self+:
- *  - Each non-Array element is unchanged.
- *  - Each \Array is replaced by its individual elements.
- *
- *  With non-negative \Integer argument +level+, flattens recursively through +level+ levels:
- *
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten(0) # => [0, [1, [2, 3], 4], 5]
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten(1) # => [0, 1, [2, 3], 4, 5]
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten(2) # => [0, 1, 2, 3, 4, 5]
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten(3) # => [0, 1, 2, 3, 4, 5]
- *
- *  With no argument, a +nil+ argument, or with negative argument +level+, flattens all levels:
- *
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten # => [0, 1, 2, 3, 4, 5]
- *    [0, 1, 2].flatten # => [0, 1, 2]
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten(-1) # => [0, 1, 2, 3, 4, 5]
- *    a = [ 0, [ 1, [2, 3], 4 ], 5 ]
- *    a.flatten(-2) # => [0, 1, 2, 3, 4, 5]
- *    [0, 1, 2].flatten(-1) # => [0, 1, 2]
+ *    flatten(depth = nil) -> new_array
+ *
+ *  Returns a new array that is a recursive flattening of +self+
+ *  to +depth+ levels of recursion;
+ *  +depth+ must be an
+ *  {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects]
+ *  or +nil+.
+ *  At each level of recursion:
  *
+ *  - Each element that is an array is "flattened"
+ *    (that is, replaced by its individual array elements).
+ *  - Each element that is not an array is unchanged
+ *    (even if the element is an object that has instance method +flatten+).
+ *
+ *  With non-negative integer argument +depth+, flattens recursively through +depth+ levels:
+ *
+ *    a = [ 0, [ 1, [2, 3], 4 ], 5, {foo: 0}, Set.new([6, 7]) ]
+ *    a              # => [0, [1, [2, 3], 4], 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.flatten(0)   # => [0, [1, [2, 3], 4], 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.flatten(1  ) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.flatten(1.1) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.flatten(2)   # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.flatten(3)   # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *
+ *  With +nil+ or negative +depth+, flattens all levels.
+ *
+ *    a.flatten     # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *    a.flatten(-1) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
+ *
+ *  Related: Array#flatten!;
+ *  see also {Methods for Converting}[rdoc-ref:Array@Methods+for+Converting].
  */
 
 static VALUE
@@ -6719,10 +6832,10 @@ rb_ary_shuffle_bang(rb_execution_context_t *ec, VALUE ary, VALUE randgen)
     rb_ary_modify(ary);
     i = len = RARRAY_LEN(ary);
     RARRAY_PTR_USE(ary, ptr, {
-        while (i) {
+        while (i > 1) {
             long j = RAND_UPTO(i);
             VALUE tmp;
-            if (len != RARRAY_LEN(ary) || ptr != RARRAY_CONST_PTR_TRANSIENT(ary)) {
+            if (len != RARRAY_LEN(ary) || ptr != RARRAY_CONST_PTR(ary)) {
                 rb_raise(rb_eRuntimeError, "modified during shuffle");
             }
             tmp = ptr[--i];
@@ -6741,6 +6854,14 @@ rb_ary_shuffle(rb_execution_context_t *ec, VALUE ary, VALUE randgen)
     return ary;
 }
 
+static const rb_data_type_t ary_sample_memo_type = {
+    .wrap_struct_name = "ary_sample_memo",
+    .function = {
+        .dfree = (RUBY_DATA_FUNC)st_free_table,
+    },
+    .flags = RUBY_TYPED_WB_PROTECTED | RUBY_TYPED_FREE_IMMEDIATELY
+};
+
 static VALUE
 ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VALUE to_array)
 {
@@ -6814,7 +6935,7 @@ ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VALUE
             sorted[j] = idx[i] = k;
         }
         result = rb_ary_new_capa(n);
-        RARRAY_PTR_USE_TRANSIENT(result, ptr_result, {
+        RARRAY_PTR_USE(result, ptr_result, {
             for (i=0; i<n; i++) {
                 ptr_result[i] = RARRAY_AREF(ary, idx[i]);
             }
@@ -6822,11 +6943,9 @@ ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VALUE
     }
     else if (n <= memo_threshold / 2) {
         long max_idx = 0;
-#undef RUBY_UNTYPED_DATA_WARNING
-#define RUBY_UNTYPED_DATA_WARNING 0
-        VALUE vmemo = Data_Wrap_Struct(0, 0, st_free_table, 0);
+        VALUE vmemo = TypedData_Wrap_Struct(0, &ary_sample_memo_type, 0);
         st_table *memo = st_init_numtable_with_size(n);
-        DATA_PTR(vmemo) = memo;
+        RTYPEDDATA_DATA(vmemo) = memo;
         result = rb_ary_new_capa(n);
         RARRAY_PTR_USE(result, ptr_result, {
             for (i=0; i<n; i++) {
@@ -6837,7 +6956,7 @@ ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VALUE
             len = RARRAY_LEN(ary);
             if (len <= max_idx) n = 0;
             else if (n > len) n = len;
-            RARRAY_PTR_USE_TRANSIENT(ary, ptr_ary, {
+            RARRAY_PTR_USE(ary, ptr_ary, {
                 for (i=0; i<n; i++) {
                     long j2 = j = ptr_result[i];
                     long i2 = i;
@@ -6849,8 +6968,9 @@ ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VALUE
                 }
             });
         });
-        DATA_PTR(vmemo) = 0;
+        RTYPEDDATA_DATA(vmemo) = 0;
         st_free_table(memo);
+        RB_GC_GUARD(vmemo);
     }
     else {
         result = rb_ary_dup(ary);
@@ -6872,6 +6992,12 @@ ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VALUE
 }
 
 static VALUE
+ary_sized_alloc(rb_execution_context_t *ec, VALUE self)
+{
+    return rb_ary_new2(RARRAY_LEN(self));
+}
+
+static VALUE
 ary_sample0(rb_execution_context_t *ec, VALUE ary)
 {
     return ary_sample(ec, ary, rb_cRandom, Qfalse, Qfalse);
@@ -6895,36 +7021,36 @@ rb_ary_cycle_size(VALUE self, VALUE args, VALUE eobj)
 
 /*
  *  call-seq:
- *    array.cycle {|element| ... } -> nil
- *    array.cycle(count) {|element| ... } -> nil
- *    array.cycle -> new_enumerator
- *    array.cycle(count) -> new_enumerator
+ *    cycle(count = nil) {|element| ... } -> nil
+ *    cycle(count = nil) -> new_enumerator
  *
- *  When called with positive \Integer argument +count+ and a block,
- *  calls the block with each element, then does so again,
+ *  With a block given, may call the block, depending on the value of argument +count+;
+ *  +count+ must be an
+ *  {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects],
+ *  or +nil+.
+ *
+ *  When +count+ is positive,
+ *  calls the block with each element, then does so repeatedly,
  *  until it has done so +count+ times; returns +nil+:
  *
  *    output = []
  *    [0, 1].cycle(2) {|element| output.push(element) } # => nil
  *    output # => [0, 1, 0, 1]
  *
- *  If +count+ is zero or negative, does not call the block:
+ *  When +count+ is zero or negative, does not call the block:
  *
- *    [0, 1].cycle(0) {|element| fail 'Cannot happen' } # => nil
+ *    [0, 1].cycle(0) {|element| fail 'Cannot happen' }  # => nil
  *    [0, 1].cycle(-1) {|element| fail 'Cannot happen' } # => nil
  *
- *  When a block is given, and argument is omitted or +nil+, cycles forever:
+ *  When +count+ is +nil+, cycles forever:
  *
  *    # Prints 0 and 1 forever.
  *    [0, 1].cycle {|element| puts element }
  *    [0, 1].cycle(nil) {|element| puts element }
  *
- *  When no block is given, returns a new \Enumerator:
- *
- *    [0, 1].cycle(2) # => #<Enumerator: [0, 1]:cycle(2)>
- *    [0, 1].cycle # => # => #<Enumerator: [0, 1]:cycle>
- *    [0, 1].cycle.first(5) # => [0, 1, 0, 1, 0]
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: see {Methods for Iterating}[rdoc-ref:Array@Methods+for+Iterating].
  */
 static VALUE
 rb_ary_cycle(int argc, VALUE *argv, VALUE ary)
@@ -7068,82 +7194,44 @@ rb_ary_permutation_size(VALUE ary, VALUE args, VALUE eobj)
 
 /*
  *  call-seq:
- *    array.permutation {|element| ... } -> self
- *    array.permutation(n) {|element| ... } -> self
- *    array.permutation -> new_enumerator
- *    array.permutation(n) -> new_enumerator
- *
- *  When invoked with a block, yield all permutations of elements of +self+; returns +self+.
- *  The order of permutations is indeterminate.
- *
- *  When a block and an in-range positive \Integer argument +n+ (<tt>0 < n <= self.size</tt>)
- *  are given, calls the block with all +n+-tuple permutations of +self+.
+ *    permutation(count = self.size) {|permutation| ... } -> self
+ *    permutation(count = self.size) -> new_enumerator
  *
- *  Example:
- *
- *    a = [0, 1, 2]
- *    a.permutation(2) {|permutation| p permutation }
+ *  Iterates over permutations of the elements of +self+;
+ *  the order of permutations is indeterminate.
  *
- *  Output:
- *
- *    [0, 1]
- *    [0, 2]
- *    [1, 0]
- *    [1, 2]
- *    [2, 0]
- *    [2, 1]
- *
- *  Another example:
+ *  With a block and an in-range positive integer argument +count+ (<tt>0 < count <= self.size</tt>) given,
+ *  calls the block with each permutation of +self+ of size +count+;
+ *  returns +self+:
  *
  *    a = [0, 1, 2]
- *    a.permutation(3) {|permutation| p permutation }
+ *    perms = []
+ *    a.permutation(1) {|perm| perms.push(perm) }
+ *    perms # => [[0], [1], [2]]
  *
- *  Output:
+ *    perms = []
+ *    a.permutation(2) {|perm| perms.push(perm) }
+ *    perms # => [[0, 1], [0, 2], [1, 0], [1, 2], [2, 0], [2, 1]]
  *
- *    [0, 1, 2]
- *    [0, 2, 1]
- *    [1, 0, 2]
- *    [1, 2, 0]
- *    [2, 0, 1]
- *    [2, 1, 0]
+ *    perms = []
+ *    a.permutation(3) {|perm| perms.push(perm) }
+ *    perms # => [[0, 1, 2], [0, 2, 1], [1, 0, 2], [1, 2, 0], [2, 0, 1], [2, 1, 0]]
  *
- *  When +n+ is zero, calls the block once with a new empty \Array:
+ *  When +count+ is zero, calls the block once with a new empty array:
  *
- *    a = [0, 1, 2]
- *    a.permutation(0) {|permutation| p permutation }
+ *    perms = []
+ *    a.permutation(0) {|perm| perms.push(perm) }
+ *    perms # => [[]]
  *
- *  Output:
- *
- *    []
- *
- *  When +n+ is out of range (negative or larger than <tt>self.size</tt>),
+ *  When +count+ is out of range (negative or larger than <tt>self.size</tt>),
  *  does not call the block:
  *
- *    a = [0, 1, 2]
  *    a.permutation(-1) {|permutation| fail 'Cannot happen' }
  *    a.permutation(4) {|permutation| fail 'Cannot happen' }
  *
- *  When a block given but no argument,
- *  behaves the same as <tt>a.permutation(a.size)</tt>:
- *
- *    a = [0, 1, 2]
- *    a.permutation {|permutation| p permutation }
- *
- *  Output:
- *
- *    [0, 1, 2]
- *    [0, 2, 1]
- *    [1, 0, 2]
- *    [1, 2, 0]
- *    [2, 0, 1]
- *    [2, 1, 0]
- *
- *  Returns a new \Enumerator if no block given:
- *
- *    a = [0, 1, 2]
- *    a.permutation # => #<Enumerator: [0, 1, 2]:permutation>
- *    a.permutation(2) # => #<Enumerator: [0, 1, 2]:permutation(2)>
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: {Methods for Iterating}[rdoc-ref:Array@Methods+for+Iterating].
  */
 
 static VALUE
@@ -7216,56 +7304,46 @@ rb_ary_combination_size(VALUE ary, VALUE args, VALUE eobj)
 
 /*
  *  call-seq:
- *    array.combination(n) {|element| ... } -> self
- *    array.combination(n) -> new_enumerator
- *
- *  Calls the block, if given, with combinations of elements of +self+;
- *  returns +self+. The order of combinations is indeterminate.
+ *    combination(count) {|element| ... } -> self
+ *    combination(count) -> new_enumerator
  *
- *  When a block and an in-range positive \Integer argument +n+ (<tt>0 < n <= self.size</tt>)
- *  are given, calls the block with all +n+-tuple combinations of +self+.
- *
- *  Example:
+ *  When a block and a positive
+ *  {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects]
+ *  argument +count+ (<tt>0 < count <= self.size</tt>)
+ *  are given, calls the block with each combination of +self+ of size +count+;
+ *  returns +self+:
  *
- *    a = [0, 1, 2]
- *    a.combination(2) {|combination| p combination }
+ *    a = %w[a b c]                                   # => ["a", "b", "c"]
+ *    a.combination(2) {|combination| p combination } # => ["a", "b", "c"]
  *
  *  Output:
  *
- *    [0, 1]
- *    [0, 2]
- *    [1, 2]
+ *    ["a", "b"]
+ *    ["a", "c"]
+ *    ["b", "c"]
  *
- *  Another example:
+ *  The order of the yielded combinations is not guaranteed.
  *
- *    a = [0, 1, 2]
- *    a.combination(3) {|combination| p combination }
+ *  When +count+ is zero, calls the block once with a new empty array:
  *
- *  Output:
- *
- *    [0, 1, 2]
- *
- *  When +n+ is zero, calls the block once with a new empty \Array:
- *
- *    a = [0, 1, 2]
- *    a1 = a.combination(0) {|combination| p combination }
+ *    a.combination(0) {|combination| p combination }
+ *    [].combination(0) {|combination| p combination }
  *
  *  Output:
  *
  *    []
+ *    []
  *
- *  When +n+ is out of range (negative or larger than <tt>self.size</tt>),
+ *  When +count+ is negative or larger than +self.size+ and +self+ is non-empty,
  *  does not call the block:
  *
- *    a = [0, 1, 2]
- *    a.combination(-1) {|combination| fail 'Cannot happen' }
- *    a.combination(4) {|combination| fail 'Cannot happen' }
- *
- *  Returns a new \Enumerator if no block given:
+ *    a.combination(-1) {|combination| fail 'Cannot happen' } # => ["a", "b", "c"]
+ *    a.combination(4)  {|combination| fail 'Cannot happen' } # => ["a", "b", "c"]
  *
- *    a = [0, 1, 2]
- *    a.combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: Array#permutation;
+ *  see also {Methods for Iterating}[rdoc-ref:Array@Methods+for+Iterating].
  */
 
 static VALUE
@@ -7352,68 +7430,41 @@ rb_ary_repeated_permutation_size(VALUE ary, VALUE args, VALUE eobj)
 
 /*
  *  call-seq:
- *    array.repeated_permutation(n) {|permutation| ... } -> self
- *    array.repeated_permutation(n) -> new_enumerator
+ *    repeated_permutation(size) {|permutation| ... } -> self
+ *    repeated_permutation(size) -> new_enumerator
  *
- *  Calls the block with each repeated permutation of length +n+ of the elements of +self+;
- *  each permutation is an \Array;
+ *  With a block given, calls the block with each repeated permutation of length +size+
+ *  of the elements of +self+;
+ *  each permutation is an array;
  *  returns +self+. The order of the permutations is indeterminate.
  *
- *  When a block and a positive \Integer argument +n+ are given, calls the block with each
- *  +n+-tuple repeated permutation of the elements of +self+.
- *  The number of permutations is <tt>self.size**n</tt>.
- *
- *  +n+ = 1:
- *
- *    a = [0, 1, 2]
- *    a.repeated_permutation(1) {|permutation| p permutation }
- *
- *  Output:
- *
- *    [0]
- *    [1]
- *    [2]
+ *  If a positive integer argument +size+ is given,
+ *  calls the block with each +size+-tuple repeated permutation of the elements of +self+.
+ *  The number of permutations is <tt>self.size**size</tt>.
  *
- *  +n+ = 2:
- *
- *    a.repeated_permutation(2) {|permutation| p permutation }
- *
- *  Output:
+ *  Examples:
  *
- *    [0, 0]
- *    [0, 1]
- *    [0, 2]
- *    [1, 0]
- *    [1, 1]
- *    [1, 2]
- *    [2, 0]
- *    [2, 1]
- *    [2, 2]
+ *  - +size+ is 1:
  *
- *  If +n+ is zero, calls the block once with an empty \Array.
+ *      p = []
+ *      [0, 1, 2].repeated_permutation(1) {|permutation| p.push(permutation) }
+ *      p # => [[0], [1], [2]]
  *
- *  If +n+ is negative, does not call the block:
+ *  - +size+ is 2:
  *
- *    a.repeated_permutation(-1) {|permutation| fail 'Cannot happen' }
+ *      p = []
+ *      [0, 1, 2].repeated_permutation(2) {|permutation| p.push(permutation) }
+ *      p # => [[0, 0], [0, 1], [0, 2], [1, 0], [1, 1], [1, 2], [2, 0], [2, 1], [2, 2]]
  *
- *  Returns a new \Enumerator if no block given:
+ *  If +size+ is zero, calls the block once with an empty array.
  *
- *    a = [0, 1, 2]
- *    a.repeated_permutation(2) # => #<Enumerator: [0, 1, 2]:permutation(2)>
+ *  If +size+ is negative, does not call the block:
  *
- *  Using Enumerators, it's convenient to show the permutations and counts
- *  for some values of +n+:
+ *    [0, 1, 2].repeated_permutation(-1) {|permutation| fail 'Cannot happen' }
  *
- *    e = a.repeated_permutation(0)
- *    e.size # => 1
- *    e.to_a # => [[]]
- *    e = a.repeated_permutation(1)
- *    e.size # => 3
- *    e.to_a # => [[0], [1], [2]]
- *    e = a.repeated_permutation(2)
- *    e.size # => 9
- *    e.to_a # => [[0, 0], [0, 1], [0, 2], [1, 0], [1, 1], [1, 2], [2, 0], [2, 1], [2, 2]]
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 static VALUE
 rb_ary_repeated_permutation(VALUE ary, VALUE num)
@@ -7484,65 +7535,41 @@ rb_ary_repeated_combination_size(VALUE ary, VALUE args, VALUE eobj)
 
 /*
  *  call-seq:
- *    array.repeated_combination(n) {|combination| ... } -> self
- *    array.repeated_combination(n) -> new_enumerator
+ *    repeated_combination(size) {|combination| ... } -> self
+ *    repeated_combination(size) -> new_enumerator
  *
- *  Calls the block with each repeated combination of length +n+ of the elements of +self+;
- *  each combination is an \Array;
+ *  With a block given, calls the block with each repeated combination of length +size+
+ *  of the elements of +self+;
+ *  each combination is an array;
  *  returns +self+. The order of the combinations is indeterminate.
  *
- *  When a block and a positive \Integer argument +n+ are given, calls the block with each
- *  +n+-tuple repeated combination of the elements of +self+.
- *  The number of combinations is <tt>(n+1)(n+2)/2</tt>.
- *
- *  +n+ = 1:
- *
- *    a = [0, 1, 2]
- *    a.repeated_combination(1) {|combination| p combination }
- *
- *  Output:
+ *  If a positive integer argument +size+ is given,
+ *  calls the block with each +size+-tuple repeated combination of the elements of +self+.
+ *  The number of combinations is <tt>(size+1)(size+2)/2</tt>.
  *
- *    [0]
- *    [1]
- *    [2]
- *
- *  +n+ = 2:
- *
- *    a.repeated_combination(2) {|combination| p combination }
- *
- *  Output:
+ *  Examples:
  *
- *    [0, 0]
- *    [0, 1]
- *    [0, 2]
- *    [1, 1]
- *    [1, 2]
- *    [2, 2]
+ *  - +size+ is 1:
  *
- *  If +n+ is zero, calls the block once with an empty \Array.
+ *      c = []
+ *      [0, 1, 2].repeated_combination(1) {|combination| c.push(combination) }
+ *      c # => [[0], [1], [2]]
  *
- *  If +n+ is negative, does not call the block:
+ *  - +size+ is 2:
  *
- *    a.repeated_combination(-1) {|combination| fail 'Cannot happen' }
+ *      c = []
+ *      [0, 1, 2].repeated_combination(2) {|combination| c.push(combination) }
+ *      c # => [[0, 0], [0, 1], [0, 2], [1, 1], [1, 2], [2, 2]]
  *
- *  Returns a new \Enumerator if no block given:
+ *  If +size+ is zero, calls the block once with an empty array.
  *
- *    a = [0, 1, 2]
- *    a.repeated_combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>
+ *  If +size+ is negative, does not call the block:
  *
- *  Using Enumerators, it's convenient to show the combinations and counts
- *  for some values of +n+:
+ *    [0, 1, 2].repeated_combination(-1) {|combination| fail 'Cannot happen' }
  *
- *    e = a.repeated_combination(0)
- *    e.size # => 1
- *    e.to_a # => [[]]
- *    e = a.repeated_combination(1)
- *    e.size # => 3
- *    e.to_a # => [[0], [1], [2]]
- *    e = a.repeated_combination(2)
- *    e.size # => 6
- *    e.to_a # => [[0, 0], [0, 1], [0, 2], [1, 1], [1, 2], [2, 2]]
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
 static VALUE
@@ -7582,62 +7609,55 @@ rb_ary_repeated_combination(VALUE ary, VALUE num)
 
 /*
  *  call-seq:
- *    array.product(*other_arrays) -> new_array
- *    array.product(*other_arrays) {|combination| ... } -> self
+ *    product(*other_arrays) -> new_array
+ *    product(*other_arrays) {|combination| ... } -> self
  *
- *  Computes and returns or yields all combinations of elements from all the Arrays,
+ *  Computes all combinations of elements from all the arrays,
  *  including both +self+ and +other_arrays+:
  *
  *  - The number of combinations is the product of the sizes of all the arrays,
  *    including both +self+ and +other_arrays+.
  *  - The order of the returned combinations is indeterminate.
  *
- *  When no block is given, returns the combinations as an \Array of Arrays:
+ *  With no block given, returns the combinations as an array of arrays:
  *
- *    a = [0, 1, 2]
- *    a1 = [3, 4]
- *    a2 = [5, 6]
- *    p = a.product(a1)
- *    p.size # => 6 # a.size * a1.size
- *    p # => [[0, 3], [0, 4], [1, 3], [1, 4], [2, 3], [2, 4]]
- *    p = a.product(a1, a2)
- *    p.size # => 12 # a.size * a1.size * a2.size
- *    p # => [[0, 3, 5], [0, 3, 6], [0, 4, 5], [0, 4, 6], [1, 3, 5], [1, 3, 6], [1, 4, 5], [1, 4, 6], [2, 3, 5], [2, 3, 6], [2, 4, 5], [2, 4, 6]]
- *
- *  If any argument is an empty \Array, returns an empty \Array.
- *
- *  If no argument is given, returns an \Array of 1-element Arrays,
- *  each containing an element of +self+:
- *
- *    a.product # => [[0], [1], [2]]
+ *    p = [0, 1].product([2, 3])
+ *    # => [[0, 2], [0, 3], [1, 2], [1, 3]]
+ *    p.size # => 4
+ *    p = [0, 1].product([2, 3], [4, 5])
+ *    # => [[0, 2, 4], [0, 2, 5], [0, 3, 4], [0, 3, 5], [1, 2, 4], [1, 2, 5], [1, 3, 4], [1, 3,...
+ *    p.size # => 8
  *
- *  When a block is given, yields each combination as an \Array; returns +self+:
+ *  If +self+ or any argument is empty, returns an empty array:
  *
- *    a.product(a1) {|combination| p combination }
+ *    [].product([2, 3], [4, 5]) # => []
+ *    [0, 1].product([2, 3], []) # => []
  *
- *  Output:
+ *  If no argument is given, returns an array of 1-element arrays,
+ *  each containing an element of +self+:
  *
- *    [0, 3]
- *    [0, 4]
- *    [1, 3]
- *    [1, 4]
- *    [2, 3]
- *    [2, 4]
+ *    a.product # => [[0], [1], [2]]
  *
- *  If any argument is an empty \Array, does not call the block:
+ *  With a block given, calls the block with each combination; returns +self+:
  *
- *    a.product(a1, a2, []) {|combination| fail 'Cannot happen' }
+ *    p = []
+ *    [0, 1].product([2, 3]) {|combination| p.push(combination) }
+ *    p # => [[0, 2], [0, 3], [1, 2], [1, 3]]
  *
- *  If no argument is given, yields each element of +self+ as a 1-element \Array:
+ *  If +self+ or any argument is empty, does not call the block:
  *
- *    a.product {|combination| p combination }
+ *    [].product([2, 3], [4, 5]) {|combination| fail 'Cannot happen' }
+ *    # => []
+ *    [0, 1].product([2, 3], []) {|combination| fail 'Cannot happen' }
+ *    # => [0, 1]
  *
- *  Output:
+ *  If no argument is given, calls the block with each element of +self+ as a 1-element array:
  *
- *    [0]
- *    [1]
- *    [2]
+ *    p = []
+ *    [0, 1].product {|combination| p.push(combination) }
+ *    p # => [[0], [1]]
  *
+ *  Related: see {Methods for Combining}[rdoc-ref:Array@Methods+for+Combining].
  */
 
 static VALUE
@@ -7730,20 +7750,20 @@ done:
 
 /*
  *  call-seq:
- *    array.take(n) -> new_array
- *
- *  Returns a new \Array containing the first +n+ element of +self+,
- *  where +n+ is a non-negative \Integer;
- *  does not modify +self+.
+ *    take(count) -> new_array
  *
- *  Examples:
+ *  Returns a new array containing the first +count+ element of +self+
+ *  (as available);
+ *  +count+ must be a non-negative numeric;
+ *  does not modify +self+:
  *
- *    a = [0, 1, 2, 3, 4, 5]
- *    a.take(1) # => [0]
- *    a.take(2) # => [0, 1]
- *    a.take(50) # => [0, 1, 2, 3, 4, 5]
- *    a # => [0, 1, 2, 3, 4, 5]
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.take(2)   # => ["a", "b"]
+ *    a.take(2.1) # => ["a", "b"]
+ *    a.take(50)  # => ["a", "b", "c", "d"]
+ *    a.take(0)   # => []
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -7758,25 +7778,23 @@ rb_ary_take(VALUE obj, VALUE n)
 
 /*
  *  call-seq:
- *    array.take_while {|element| ... } -> new_array
- *    array.take_while -> new_enumerator
- *
- *  Returns a new \Array containing zero or more leading elements of +self+;
- *  does not modify +self+.
+ *    take_while {|element| ... } -> new_array
+ *    take_while -> new_enumerator
  *
  *  With a block given, calls the block with each successive element of +self+;
- *  stops if the block returns +false+ or +nil+;
- *  returns a new \Array containing those elements for which the block returned a truthy value:
+ *  stops iterating if the block returns +false+ or +nil+;
+ *  returns a new array containing those elements for which the block returned a truthy value:
  *
  *    a = [0, 1, 2, 3, 4, 5]
  *    a.take_while {|element| element < 3 } # => [0, 1, 2]
- *    a.take_while {|element| true } # => [0, 1, 2, 3, 4, 5]
- *    a # => [0, 1, 2, 3, 4, 5]
+ *    a.take_while {|element| true }        # => [0, 1, 2, 3, 4, 5]
+ *    a.take_while {|element| false }       # => []
  *
- *  With no block given, returns a new \Enumerator:
+ *  With no block given, returns a new Enumerator.
  *
- *    [0, 1].take_while # => #<Enumerator: [0, 1]:take_while>
+ *  Does not modify +self+.
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -7793,10 +7811,10 @@ rb_ary_take_while(VALUE ary)
 
 /*
  *  call-seq:
- *    array.drop(n) -> new_array
+ *    drop(count) -> new_array
  *
- *  Returns a new \Array containing all but the first +n+ element of +self+,
- *  where +n+ is a non-negative \Integer;
+ *  Returns a new array containing all but the first +count+ element of +self+,
+ *  where +count+ is a non-negative integer;
  *  does not modify +self+.
  *
  *  Examples:
@@ -7805,7 +7823,9 @@ rb_ary_take_while(VALUE ary)
  *    a.drop(0) # => [0, 1, 2, 3, 4, 5]
  *    a.drop(1) # => [1, 2, 3, 4, 5]
  *    a.drop(2) # => [2, 3, 4, 5]
+ *    a.drop(9) # => []
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -7824,23 +7844,20 @@ rb_ary_drop(VALUE ary, VALUE n)
 
 /*
  *  call-seq:
- *    array.drop_while {|element| ... } -> new_array
- *    array.drop_while -> new_enumerator
-
- *  Returns a new \Array containing zero or more trailing elements of +self+;
- *  does not modify +self+.
+ *    drop_while {|element| ... } -> new_array
+ *    drop_while -> new_enumerator
  *
  *  With a block given, calls the block with each successive element of +self+;
  *  stops if the block returns +false+ or +nil+;
- *  returns a new \Array _omitting_ those elements for which the block returned a truthy value:
+ *  returns a new array _omitting_ those elements for which the block returned a truthy value;
+ *  does not modify +self+:
  *
  *    a = [0, 1, 2, 3, 4, 5]
  *    a.drop_while {|element| element < 3 } # => [3, 4, 5]
  *
- *  With no block given, returns a new \Enumerator:
- *
- *    [0, 1].drop_while # => # => #<Enumerator: [0, 1]:drop_while>
+ *  With no block given, returns a new Enumerator.
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -7857,35 +7874,41 @@ rb_ary_drop_while(VALUE ary)
 
 /*
  *  call-seq:
- *    array.any? -> true or false
- *    array.any? {|element| ... } -> true or false
- *    array.any?(obj) -> true or false
+ *    any? -> true or false
+ *    any?(object) -> true or false
+ *    any? {|element| ... } -> true or false
  *
- *  Returns +true+ if any element of +self+ meets a given criterion.
+ *  Returns whether for any element of +self+, a given criterion is satisfied.
  *
- *  With no block given and no argument, returns +true+ if +self+ has any truthy element,
- *  +false+ otherwise:
+ *  With no block and no argument, returns whether any element of +self+ is truthy:
  *
- *    [nil, 0, false].any? # => true
- *    [nil, false].any? # => false
- *    [].any? # => false
+ *    [nil, false, []].any? # => true  # Array object is truthy.
+ *    [nil, false, {}].any? # => true  # Hash object is truthy.
+ *    [nil, false, ''].any? # => true  # String object is truthy.
+ *    [nil, false].any?     # => false # Nil and false are not truthy.
  *
- *  With a block given and no argument, calls the block with each element in +self+;
- *  returns +true+ if the block returns any truthy value, +false+ otherwise:
+ *  With argument +object+ given,
+ *  returns whether <tt>object === ele</tt> for any element +ele+ in +self+:
  *
- *    [0, 1, 2].any? {|element| element > 1 } # => true
- *    [0, 1, 2].any? {|element| element > 2 } # => false
+ *    [nil, false, 0].any?(0)          # => true
+ *    [nil, false, 1].any?(0)          # => false
+ *    [nil, false, 'food'].any?(/foo/) # => true
+ *    [nil, false, 'food'].any?(/bar/) # => false
  *
- *  If argument +obj+ is given, returns +true+ if +obj+.<tt>===</tt> any element,
- *  +false+ otherwise:
+ *  With a block given,
+ *  calls the block with each element in +self+;
+ *  returns whether the block returns any truthy value:
+ *
+ *    [0, 1, 2].any? {|ele| ele < 1 } # => true
+ *    [0, 1, 2].any? {|ele| ele < 0 } # => false
  *
- *    ['food', 'drink'].any?(/foo/) # => true
- *    ['food', 'drink'].any?(/bar/) # => false
- *    [].any?(/foo/) # => false
- *    [0, 1, 2].any?(1) # => true
- *    [0, 1, 2].any?(3) # => false
+ *  With both a block and argument +object+ given,
+ *  ignores the block and uses +object+ as above.
  *
- *  Related: Enumerable#any?
+ *  <b>Special case</b>: returns +false+ if +self+ is empty
+ *  (regardless of any given argument or block).
+ *
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -7918,34 +7941,41 @@ rb_ary_any_p(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.all? -> true or false
- *    array.all? {|element| ... } -> true or false
- *    array.all?(obj) -> true or false
+ *    all? -> true or false
+ *    all?(object) -> true or false
+ *    all? {|element| ... } -> true or false
  *
- *  Returns +true+ if all elements of +self+ meet a given criterion.
+ *  Returns whether for every element of +self+,
+ *  a given criterion is satisfied.
  *
- *  With no block given and no argument, returns +true+ if +self+ contains only truthy elements,
- *  +false+ otherwise:
+ *  With no block and no argument,
+ *  returns whether every element of +self+ is truthy:
  *
- *    [0, 1, :foo].all? # => true
- *    [0, nil, 2].all? # => false
- *    [].all? # => true
+ *    [[], {}, '', 0, 0.0, Object.new].all? # => true  # All truthy objects.
+ *    [[], {}, '', 0, 0.0, nil].all?        # => false # nil is not truthy.
+ *    [[], {}, '', 0, 0.0, false].all?      # => false # false is not truthy.
  *
- *  With a block given and no argument, calls the block with each element in +self+;
- *  returns +true+ if the block returns only truthy values, +false+ otherwise:
+ *  With argument +object+ given, returns whether <tt>object === ele</tt>
+ *  for every element +ele+ in +self+:
  *
- *    [0, 1, 2].all? { |element| element < 3 } # => true
- *    [0, 1, 2].all? { |element| element < 2 } # => false
+ *    [0, 0, 0].all?(0)                    # => true
+ *    [0, 1, 2].all?(1)                    # => false
+ *    ['food', 'fool', 'foot'].all?(/foo/) # => true
+ *    ['food', 'drink'].all?(/foo/)        # => false
  *
- *  If argument +obj+ is given, returns +true+ if <tt>obj.===</tt> every element, +false+ otherwise:
+ *  With a block given, calls the block with each element in +self+;
+ *  returns whether the block returns only truthy values:
  *
- *    ['food', 'fool', 'foot'].all?(/foo/) # => true
- *    ['food', 'drink'].all?(/bar/) # => false
- *    [].all?(/foo/) # => true
- *    [0, 0, 0].all?(0) # => true
- *    [0, 1, 2].all?(1) # => false
+ *    [0, 1, 2].all? { |ele| ele < 3 } # => true
+ *    [0, 1, 2].all? { |ele| ele < 2 } # => false
+ *
+ *  With both a block and argument +object+ given,
+ *  ignores the block and uses +object+ as above.
+ *
+ *  <b>Special case</b>: returns +true+ if +self+ is empty
+ *  (regardless of any given argument or block).
  *
- *  Related: Enumerable#all?
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -7978,34 +8008,35 @@ rb_ary_all_p(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.none? -> true or false
- *    array.none? {|element| ... } -> true or false
- *    array.none?(obj) -> true or false
+ *    none? -> true or false
+ *    none?(object) -> true or false
+ *    none? {|element| ... } -> true or false
  *
- *  Returns +true+ if no element of +self+ meet a given criterion.
+ *  Returns +true+ if no element of +self+ meets a given criterion, +false+ otherwise.
  *
  *  With no block given and no argument, returns +true+ if +self+ has no truthy elements,
  *  +false+ otherwise:
  *
- *    [nil, false].none? # => true
+ *    [nil, false].none?    # => true
  *    [nil, 0, false].none? # => false
- *    [].none? # => true
+ *    [].none?              # => true
+ *
+ *  With argument +object+ given, returns +false+ if for any element +element+,
+ *  <tt>object === element</tt>; +true+ otherwise:
+ *
+ *    ['food', 'drink'].none?(/bar/) # => true
+ *    ['food', 'drink'].none?(/foo/) # => false
+ *    [].none?(/foo/)                # => true
+ *    [0, 1, 2].none?(3)             # => true
+ *    [0, 1, 2].none?(1)             # => false
  *
- *  With a block given and no argument, calls the block with each element in +self+;
+ *  With a block given, calls the block with each element in +self+;
  *  returns +true+ if the block returns no truthy value, +false+ otherwise:
  *
  *    [0, 1, 2].none? {|element| element > 3 } # => true
  *    [0, 1, 2].none? {|element| element > 1 } # => false
  *
- *  If argument +obj+ is given, returns +true+ if <tt>obj.===</tt> no element, +false+ otherwise:
- *
- *    ['food', 'drink'].none?(/bar/) # => true
- *    ['food', 'drink'].none?(/foo/) # => false
- *    [].none?(/foo/) # => true
- *    [0, 1, 2].none?(3) # => true
- *    [0, 1, 2].none?(1) # => false
- *
- *  Related: Enumerable#none?
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -8038,9 +8069,9 @@ rb_ary_none_p(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.one? -> true or false
- *    array.one? {|element| ... } -> true or false
- *    array.one?(obj) -> true or false
+ *    one? -> true or false
+ *    one? {|element| ... } -> true or false
+ *    one?(object) -> true or false
  *
  *  Returns +true+ if exactly one element of +self+ meets a given criterion.
  *
@@ -8052,14 +8083,14 @@ rb_ary_none_p(int argc, VALUE *argv, VALUE ary)
  *    [nil, nil].one? # => false
  *    [].one? # => false
  *
- *  With a block given and no argument, calls the block with each element in +self+;
+ *  With a block given, calls the block with each element in +self+;
  *  returns +true+ if the block a truthy value for exactly one element, +false+ otherwise:
  *
  *    [0, 1, 2].one? {|element| element > 0 } # => false
  *    [0, 1, 2].one? {|element| element > 1 } # => true
  *    [0, 1, 2].one? {|element| element > 2 } # => false
  *
- *  If argument +obj+ is given, returns +true+ if <tt>obj.===</tt> exactly one element,
+ *  With argument +object+ given, returns +true+ if for exactly one element +element+, <tt>object === element</tt>;
  *  +false+ otherwise:
  *
  *    [0, 1, 2].one?(0) # => true
@@ -8069,7 +8100,7 @@ rb_ary_none_p(int argc, VALUE *argv, VALUE ary)
  *    ['food', 'drink'].one?(/foo/) # => true
  *    [].one?(/foo/) # => false
  *
- *  Related: Enumerable#one?
+ *  Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
  */
 
 static VALUE
@@ -8112,11 +8143,11 @@ rb_ary_one_p(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *    array.dig(index, *identifiers) -> object
+ *    dig(index, *identifiers) -> object
  *
- *  Finds and returns the object in nested objects
- *  that is specified by +index+ and +identifiers+.
- *  The nested objects may be instances of various classes.
+ *  Finds and returns the object in nested object
+ *  specified by +index+ and +identifiers+;
+ *  the nested objects may be instances of various classes.
  *  See {Dig Methods}[rdoc-ref:dig_methods.rdoc].
  *
  *  Examples:
@@ -8127,6 +8158,7 @@ rb_ary_one_p(int argc, VALUE *argv, VALUE ary)
  *    a.dig(1, 2, 0) # => :bat
  *    a.dig(1, 2, 3) # => nil
  *
+ *  Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
  */
 
 static VALUE
@@ -8144,7 +8176,7 @@ finish_exact_sum(long n, VALUE r, VALUE v, int z)
 {
     if (n != 0)
         v = rb_fix_plus(LONG2FIX(n), v);
-    if (r != Qundef) {
+    if (!UNDEF_P(r)) {
         v = rb_rational_plus(r, v);
     }
     else if (!n && z) {
@@ -8155,40 +8187,41 @@ finish_exact_sum(long n, VALUE r, VALUE v, int z)
 
 /*
  * call-seq:
- *   array.sum(init = 0) -> object
- *   array.sum(init = 0) {|element| ... } -> object
+ *   sum(init = 0) -> object
+ *   sum(init = 0) {|element| ... } -> object
  *
- *  When no block is given, returns the object equivalent to:
+ *  With no block given, returns the sum of +init+ and all elements of +self+;
+ *  for array +array+ and value +init+, equivalent to:
  *
  *    sum = init
  *    array.each {|element| sum += element }
  *    sum
  *
- *  For example, <tt>[e1, e2, e3].sum</tt> returns <tt>init + e1 + e2 + e3</tt>.
+ *  For example, <tt>[e0, e1, e2].sum</tt> returns <tt>init + e0 + e1 + e2</tt>.
  *
  *  Examples:
  *
- *    a = [0, 1, 2, 3]
- *    a.sum # => 6
- *    a.sum(100) # => 106
+ *    [0, 1, 2, 3].sum                 # => 6
+ *    [0, 1, 2, 3].sum(100)            # => 106
+ *    ['abc', 'def', 'ghi'].sum('jkl') # => "jklabcdefghi"
+ *    [[:foo, :bar], ['foo', 'bar']].sum([2, 3])
+ *    # => [2, 3, :foo, :bar, "foo", "bar"]
  *
- *  The elements need not be numeric, but must be <tt>+</tt>-compatible
- *  with each other and with +init+:
+ *  The +init+ value and elements need not be numeric, but must all be <tt>+</tt>-compatible:
  *
- *    a = ['abc', 'def', 'ghi']
- *    a.sum('jkl') # => "jklabcdefghi"
+ *    # Raises TypeError: Array can't be coerced into Integer.
+ *    [[:foo, :bar], ['foo', 'bar']].sum(2)
  *
- *  When a block is given, it is called with each element
- *  and the block's return value (instead of the element itself) is used as the addend:
+ *  With a block given, calls the block with each element of +self+;
+ *  the block's return value (instead of the element itself) is used as the addend:
  *
- *    a = ['zero', 1, :two]
- *    s = a.sum('Coerced and concatenated: ') {|element| element.to_s }
- *    s # => "Coerced and concatenated: zero1two"
+ *    ['zero', 1, :two].sum('Coerced and concatenated: ') {|element| element.to_s }
+ *    # => "Coerced and concatenated: zero1two"
  *
  *  Notes:
  *
  *  - Array#join and Array#flatten may be faster than Array#sum
- *    for an \Array of Strings or an \Array of Arrays.
+ *    for an array of strings or an array of arrays.
  *  - Array#sum method may not respect method redefinition of "+" methods such as Integer#+.
  *
  */
@@ -8209,6 +8242,12 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
 
     n = 0;
     r = Qundef;
+
+    if (!FIXNUM_P(v) && !RB_BIGNUM_TYPE_P(v) && !RB_TYPE_P(v, T_RATIONAL)) {
+        i = 0;
+        goto init_is_a_value;
+    }
+
     for (i = 0; i < RARRAY_LEN(ary); i++) {
         e = RARRAY_AREF(ary, i);
         if (block_given)
@@ -8223,7 +8262,7 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
         else if (RB_BIGNUM_TYPE_P(e))
             v = rb_big_plus(e, v);
         else if (RB_TYPE_P(e, T_RATIONAL)) {
-            if (r == Qundef)
+            if (UNDEF_P(r))
                 r = e;
             else
                 r = rb_rational_plus(r, e);
@@ -8293,6 +8332,7 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
     }
 
     goto has_some_value;
+    init_is_a_value:
     for (; i < RARRAY_LEN(ary); i++) {
         e = RARRAY_AREF(ary, i);
         if (block_given)
@@ -8303,6 +8343,7 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
     return v;
 }
 
+/* :nodoc: */
 static VALUE
 rb_ary_deconstruct(VALUE ary)
 {
@@ -8310,15 +8351,37 @@ rb_ary_deconstruct(VALUE ary)
 }
 
 /*
- *  An \Array is an ordered, integer-indexed collection of objects, called _elements_.
- *  Any object (even another array) may be an array element,
- *  and an array can contain objects of different types.
+ *  An \Array object is an ordered, integer-indexed collection of objects,
+ *  called _elements_;
+ *  the object represents
+ *  an {array data structure}[https://en.wikipedia.org/wiki/Array_(data_structure)].
+ *
+ *  An element may be any object (even another array);
+ *  elements may be any mixture of objects of different types.
+ *
+ *  Important data structures that use arrays include:
+ *
+ *  - {Coordinate vector}[https://en.wikipedia.org/wiki/Coordinate_vector].
+ *  - {Matrix}[https://en.wikipedia.org/wiki/Matrix_(mathematics)].
+ *  - {Heap}[https://en.wikipedia.org/wiki/Heap_(data_structure)].
+ *  - {Hash table}[https://en.wikipedia.org/wiki/Hash_table].
+ *  - {Deque (double-ended queue)}[https://en.wikipedia.org/wiki/Double-ended_queue].
+ *  - {Queue}[https://en.wikipedia.org/wiki/Queue_(abstract_data_type)].
+ *  - {Stack}[https://en.wikipedia.org/wiki/Stack_(abstract_data_type)].
+ *
+ *  There are also array-like data structures:
+ *
+ *  - {Associative array}[https://en.wikipedia.org/wiki/Associative_array] (see Hash).
+ *  - {Directory}[https://en.wikipedia.org/wiki/Directory_(computing)] (see Dir).
+ *  - {Environment}[https://en.wikipedia.org/wiki/Environment_variable] (see ENV).
+ *  - {Set}[https://en.wikipedia.org/wiki/Set_(abstract_data_type)] (see Set).
+ *  - {String}[https://en.wikipedia.org/wiki/String_(computer_science)] (see String).
  *
  *  == \Array Indexes
  *
  *  \Array indexing starts at 0, as in C or Java.
  *
- *  A positive index is an offset from the first element:
+ *  A non-negative index is an offset from the first element:
  *
  *  - Index 0 indicates the first element.
  *  - Index 1 indicates the second element.
@@ -8330,6 +8393,9 @@ rb_ary_deconstruct(VALUE ary)
  *  - Index -2 indicates the next-to-last element.
  *  - ...
  *
+ *
+ *  === In-Range and Out-of-Range Indexes
+ *
  *  A non-negative index is <i>in range</i> if and only if it is smaller than
  *  the size of the array.  For a 3-element array:
  *
@@ -8342,31 +8408,32 @@ rb_ary_deconstruct(VALUE ary)
  *  - Indexes -1 through -3 are in range.
  *  - Index -4 is out of range.
  *
+ *  === Effective Index
+ *
  *  Although the effective index into an array is always an integer,
- *  some methods (both within and outside of class \Array)
+ *  some methods (both within class \Array and elsewhere)
  *  accept one or more non-integer arguments that are
  *  {integer-convertible objects}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects].
  *
- *
  *  == Creating Arrays
  *
  *  You can create an \Array object explicitly with:
  *
- *  - An {array literal}[rdoc-ref:literals.rdoc@Array+Literals]:
+ *  - An {array literal}[rdoc-ref:syntax/literals.rdoc@Array+Literals]:
  *
  *      [1, 'one', :one, [2, 'two', :two]]
  *
- *  - A {%w or %W: string-array Literal}[rdoc-ref:literals.rdoc@25w+and+-25W-3A+String-Array+Literals]:
+ *  - A {%w or %W string-array Literal}[rdoc-ref:syntax/literals.rdoc@25w+and+-25W-3A+String-Array+Literals]:
  *
  *      %w[foo bar baz] # => ["foo", "bar", "baz"]
  *      %w[1 % *]       # => ["1", "%", "*"]
  *
- *  - A {%i pr %I: symbol-array Literal}[rdoc-ref:literals.rdoc@25i+and+-25I-3A+Symbol-Array+Literals]:
+ *  - A {%i or %I symbol-array Literal}[rdoc-ref:syntax/literals.rdoc@25i+and+-25I-3A+Symbol-Array+Literals]:
  *
  *      %i[foo bar baz] # => [:foo, :bar, :baz]
  *      %i[1 % *]       # => [:"1", :%, :*]
  *
- *  - \Method Kernel#Array:
+ *  - Method Kernel#Array:
  *
  *      Array(["a", "b"])             # => ["a", "b"]
  *      Array(1..5)                   # => [1, 2, 3, 4, 5]
@@ -8375,7 +8442,7 @@ rb_ary_deconstruct(VALUE ary)
  *      Array(1)                      # => [1]
  *      Array({:a => "a", :b => "b"}) # => [[:a, "a"], [:b, "b"]]
  *
- *  - \Method Array.new:
+ *  - Method Array.new:
  *
  *      Array.new               # => []
  *      Array.new(3)            # => [nil, nil, nil]
@@ -8430,8 +8497,8 @@ rb_ary_deconstruct(VALUE ary)
  *
  *  == Example Usage
  *
- *  In addition to the methods it mixes in through the Enumerable module, the
- *  \Array class has proprietary methods for accessing, searching and otherwise
+ *  In addition to the methods it mixes in through the Enumerable module,
+ *  class \Array has proprietary methods for accessing, searching and otherwise
  *  manipulating arrays.
  *
  *  Some of the more common ones are illustrated below.
@@ -8481,7 +8548,7 @@ rb_ary_deconstruct(VALUE ary)
  *
  *  == Obtaining Information about an \Array
  *
- *  Arrays keep track of their own length at all times.  To query an array
+ *  An array keeps track of its own length at all times.  To query an array
  *  about the number of elements it contains, use #length, #count or #size.
  *
  *    browsers = ['Chrome', 'Firefox', 'Safari', 'Opera', 'IE']
@@ -8496,7 +8563,7 @@ rb_ary_deconstruct(VALUE ary)
  *
  *    browsers.include?('Konqueror') #=> false
  *
- *  == Adding Items to Arrays
+ *  == Adding Items to an \Array
  *
  *  Items can be added to the end of an array by using either #push or #<<
  *
@@ -8557,11 +8624,11 @@ rb_ary_deconstruct(VALUE ary)
  *     arr = [2, 5, 6, 556, 6, 6, 8, 9, 0, 123, 556]
  *     arr.uniq #=> [2, 5, 6, 556, 8, 9, 0, 123]
  *
- *  == Iterating over Arrays
+ *  == Iterating over an \Array
  *
- *  Like all classes that include the Enumerable module, \Array has an each
+ *  Like all classes that include the Enumerable module, class \Array has an each
  *  method, which defines what elements should be iterated over and how.  In
- *  case of Array's #each, all elements in the \Array instance are yielded to
+ *  case of Array#each, all elements in +self+ are yielded to
  *  the supplied block in sequence.
  *
  *  Note that this operation leaves the array unchanged.
@@ -8621,7 +8688,7 @@ rb_ary_deconstruct(VALUE ary)
  *
  *  == What's Here
  *
- *  First, what's elsewhere. \Class \Array:
+ *  First, what's elsewhere. Class \Array:
  *
  *  - Inherits from {class Object}[rdoc-ref:Object@What-27s+Here].
  *  - Includes {module Enumerable}[rdoc-ref:Enumerable@What-27s+Here],
@@ -8646,148 +8713,132 @@ rb_ary_deconstruct(VALUE ary)
  *  - ::new: Returns a new array.
  *  - ::try_convert: Returns a new array created from a given object.
  *
+ *  See also {Creating Arrays}[rdoc-ref:Array@Creating+Arrays].
+ *
  *  === Methods for Querying
  *
- *  - #length, #size: Returns the count of elements.
- *  - #include?: Returns whether any element <tt>==</tt> a given object.
- *  - #empty?: Returns whether there are no elements.
  *  - #all?: Returns whether all elements meet a given criterion.
  *  - #any?: Returns whether any element meets a given criterion.
+ *  - #count: Returns the count of elements that meet a given criterion.
+ *  - #empty?: Returns whether there are no elements.
+ *  - #find_index (aliased as #index): Returns the index of the first element that meets a given criterion.
+ *  - #hash: Returns the integer hash code.
+ *  - #include?: Returns whether any element <tt>==</tt> a given object.
+ *  - #length (aliased as #size): Returns the count of elements.
  *  - #none?: Returns whether no element <tt>==</tt> a given object.
  *  - #one?: Returns whether exactly one element <tt>==</tt> a given object.
- *  - #count: Returns the count of elements that meet a given criterion.
- *  - #find_index, #index: Returns the index of the first element that meets a given criterion.
  *  - #rindex: Returns the index of the last element that meets a given criterion.
- *  - #hash: Returns the integer hash code.
  *
  *  === Methods for Comparing
  *
- *  - #<=>: Returns -1, 0, or 1 * as +self+ is less than, equal to, or
- *    greater than a given object.
- *  - #==: Returns whether each element in +self+ is <tt>==</tt> to the corresponding element
- *    in a given object.
- *  - #eql?: Returns whether each element in +self+ is <tt>eql?</tt> to the corresponding
- *    element in a given object.
+ *  - #<=>: Returns -1, 0, or 1, as +self+ is less than, equal to, or greater than a given object.
+ *  - #==: Returns whether each element in +self+ is <tt>==</tt> to the corresponding element in a given object.
+ *  - #eql?: Returns whether each element in +self+ is <tt>eql?</tt> to the corresponding element in a given object.
 
  *  === Methods for Fetching
  *
  *  These methods do not modify +self+.
  *
- *  - #[]: Returns one or more elements.
- *  - #fetch: Returns the element at a given offset.
- *  - #first: Returns one or more leading elements.
- *  - #last: Returns one or more trailing elements.
- *  - #max: Returns one or more maximum-valued elements,
- *    as determined by <tt><=></tt> or a given block.
- *  - #min: Returns one or more minimum-valued elements,
- *    as determined by <tt><=></tt> or a given block.
- *  - #minmax: Returns the minimum-valued and maximum-valued elements,
- *    as determined by <tt><=></tt> or a given block.
- *  - #assoc: Returns the first element that is an array
- *    whose first element <tt>==</tt> a given object.
- *  - #rassoc: Returns the first element that is an array
- *    whose second element <tt>==</tt> a given object.
+ *  - #[] (aliased as #slice): Returns consecutive elements as determined by a given argument.
+ *  - #assoc: Returns the first element that is an array whose first element <tt>==</tt> a given object.
  *  - #at: Returns the element at a given offset.
- *  - #values_at: Returns the elements at given offsets.
- *  - #dig: Returns the object in nested objects
- *    that is specified by a given index and additional arguments.
+ *  - #bsearch: Returns an element selected via a binary search as determined by a given block.
+ *  - #bsearch_index: Returns the index of an element selected via a binary search as determined by a given block.
+ *  - #compact: Returns an array containing all non-+nil+ elements.
+ *  - #dig: Returns the object in nested objects that is specified by a given index and additional arguments.
  *  - #drop: Returns trailing elements as determined by a given index.
- *  - #take: Returns leading elements as determined by a given index.
  *  - #drop_while: Returns trailing elements as determined by a given block.
- *  - #take_while: Returns leading elements as determined by a given block.
- *  - #slice: Returns consecutive elements as determined by a given argument.
- *  - #sort: Returns all elements in an order determined by <tt><=></tt> or a given block.
+ *  - #fetch: Returns the element at a given offset.
+ *  - #fetch_values: Returns elements at given offsets.
+ *  - #first: Returns one or more leading elements.
+ *  - #last: Returns one or more trailing elements.
+ *  - #max: Returns one or more maximum-valued elements, as determined by <tt>#<=></tt> or a given block.
+ *  - #min: Returns one or more minimum-valued elements, as determined by <tt>#<=></tt> or a given block.
+ *  - #minmax: Returns the minimum-valued and maximum-valued elements, as determined by <tt>#<=></tt> or a given block.
+ *  - #rassoc: Returns the first element that is an array whose second element <tt>==</tt> a given object.
+ *  - #reject: Returns an array containing elements not rejected by a given block.
  *  - #reverse: Returns all elements in reverse order.
- *  - #compact: Returns an array containing all non-+nil+ elements.
- *  - #select, #filter: Returns an array containing elements selected by a given block.
- *  - #uniq: Returns an array containing non-duplicate elements.
  *  - #rotate: Returns all elements with some rotated from one end to the other.
- *  - #bsearch: Returns an element selected via a binary search
- *    as determined by a given block.
- *  - #bsearch_index: Returns the index of an element selected via a binary search
- *    as determined by a given block.
  *  - #sample: Returns one or more random elements.
+ *  - #select (aliased as #filter): Returns an array containing elements selected by a given block.
  *  - #shuffle: Returns elements in a random order.
+ *  - #sort: Returns all elements in an order determined by <tt>#<=></tt> or a given block.
+ *  - #take: Returns leading elements as determined by a given index.
+ *  - #take_while: Returns leading elements as determined by a given block.
+ *  - #uniq: Returns an array containing non-duplicate elements.
+ *  - #values_at: Returns the elements at given offsets.
  *
  *  === Methods for Assigning
  *
  *  These methods add, replace, or reorder elements in +self+.
  *
+ *  - #<<: Appends an element.
  *  - #[]=: Assigns specified elements with a given object.
- *  - #push, #append, #<<: Appends trailing elements.
- *  - #unshift, #prepend: Prepends leading elements.
- *  - #insert: Inserts given objects at a given offset; does not replace elements.
  *  - #concat: Appends all elements from given arrays.
  *  - #fill: Replaces specified elements with specified objects.
- *  - #replace: Replaces the content of +self+ with the content of a given array.
+ *  - #flatten!: Replaces each nested array in +self+ with the elements from that array.
+ *  - #initialize_copy (aliased as #replace): Replaces the content of +self+ with the content of a given array.
+ *  - #insert: Inserts given objects at a given offset; does not replace elements.
+ *  - #push (aliased as #append): Appends elements.
  *  - #reverse!: Replaces +self+ with its elements reversed.
  *  - #rotate!: Replaces +self+ with its elements rotated.
  *  - #shuffle!: Replaces +self+ with its elements in random order.
- *  - #sort!: Replaces +self+ with its elements sorted,
- *    as determined by <tt><=></tt> or a given block.
+ *  - #sort!: Replaces +self+ with its elements sorted, as determined by <tt>#<=></tt> or a given block.
  *  - #sort_by!: Replaces +self+ with its elements sorted, as determined by a given block.
+ *  - #unshift (aliased as #prepend): Prepends leading elements.
  *
  *  === Methods for Deleting
  *
  *  Each of these methods removes elements from +self+:
  *
- *  - #pop: Removes and returns the last element.
- *  - #shift:  Removes and returns the first element.
- *  - #compact!: Removes all non-+nil+ elements.
+ *  - #clear: Removes all elements.
+ *  - #compact!: Removes all +nil+ elements.
  *  - #delete: Removes elements equal to a given object.
  *  - #delete_at: Removes the element at a given offset.
  *  - #delete_if: Removes elements specified by a given block.
  *  - #keep_if: Removes elements not specified by a given block.
+ *  - #pop: Removes and returns the last element.
  *  - #reject!: Removes elements specified by a given block.
- *  - #select!, #filter!: Removes elements not specified by a given block.
+ *  - #select! (aliased as #filter!): Removes elements not specified by a given block.
+ *  - #shift:  Removes and returns the first element.
  *  - #slice!: Removes and returns a sequence of elements.
  *  - #uniq!: Removes duplicates.
  *
  *  === Methods for Combining
  *
  *  - #&: Returns an array containing elements found both in +self+ and a given array.
- *  - #intersection: Returns an array containing elements found both in +self+
- *    and in each given array.
  *  - #+: Returns an array containing all elements of +self+ followed by all elements of a given array.
  *  - #-: Returns an array containing all elements of +self+ that are not found in a given array.
- *  - #|: Returns an array containing all elements of +self+ and all elements of a given array,
- *    duplicates removed.
- *  - #union: Returns an array containing all elements of +self+ and all elements of given arrays,
- *    duplicates removed.
- *  - #difference: Returns an array containing all elements of +self+ that are not found
- *    in any of the given arrays..
+ *  - #|: Returns an array containing all element of +self+ and all elements of a given array, duplicates removed.
+ *  - #difference: Returns an array containing all elements of +self+ that are not found in any of the given arrays..
+ *  - #intersection: Returns an array containing elements found both in +self+ and in each given array.
  *  - #product: Returns or yields all combinations of elements from +self+ and given arrays.
+ *  - #reverse: Returns an array containing all elements of +self+ in reverse order.
+ *  - #union: Returns an array containing all elements of +self+ and all elements of given arrays, duplicates removed.
  *
  *  === Methods for Iterating
  *
+ *  - #combination: Calls a given block with combinations of elements of +self+; a combination does not use the same element more than once.
+ *  - #cycle: Calls a given block with each element, then does so again, for a specified number of times, or forever.
  *  - #each: Passes each element to a given block.
- *  - #reverse_each:  Passes each element, in reverse order, to a given block.
  *  - #each_index: Passes each element index to a given block.
- *  - #cycle: Calls a given block with each element, then does so again,
- *    for a specified number of times, or forever.
- *  - #combination: Calls a given block with combinations of elements of +self+;
- *    a combination does not use the same element more than once.
- *  - #permutation: Calls a given block with permutations of elements of +self+;
- *    a permutation does not use the same element more than once.
- *  - #repeated_combination: Calls a given block with combinations of elements of +self+;
- *    a combination may use the same element more than once.
- *  - #repeated_permutation: Calls a given block with permutations of elements of +self+;
- *    a permutation may use the same element more than once.
+ *  - #permutation: Calls a given block with permutations of elements of +self+; a permutation does not use the same element more than once.
+ *  - #repeated_combination: Calls a given block with combinations of elements of +self+; a combination may use the same element more than once.
+ *  - #repeated_permutation: Calls a given block with permutations of elements of +self+; a permutation may use the same element more than once.
+ *  - #reverse_each:  Passes each element, in reverse order, to a given block.
  *
  *  === Methods for Converting
  *
- *  - #map, #collect: Returns an array containing the block return-value for each element.
- *  - #map!, #collect!: Replaces each element with a block return-value.
+ *  - #collect (aliased as #map): Returns an array containing the block return-value for each element.
+ *  - #collect! (aliased as #map!): Replaces each element with a block return-value.
  *  - #flatten: Returns an array that is a recursive flattening of +self+.
- *  - #flatten!: Replaces each nested array in +self+ with the elements from that array.
- *  - #inspect, #to_s: Returns a new String containing the elements.
- *  - #join: Returns a newsString containing the elements joined by the field separator.
+ *  - #inspect (aliased as #to_s): Returns a new String containing the elements.
+ *  - #join: Returns a new String containing the elements joined by the field separator.
  *  - #to_a: Returns +self+ or a new array containing all elements.
  *  - #to_ary: Returns +self+.
  *  - #to_h: Returns a new hash formed from the elements.
  *  - #transpose: Transposes +self+, which must be an array of arrays.
- *  - #zip: Returns a new array of arrays containing +self+ and given arrays;
- *    follow the link for details.
+ *  - #zip: Returns a new array of arrays containing +self+ and given arrays.
  *
  *  === Other Methods
  *
@@ -8798,7 +8849,6 @@ rb_ary_deconstruct(VALUE ary)
  *    - With string argument +field_separator+, a new string that is equivalent to
  *      <tt>join(field_separator)</tt>.
  *
- *  - #abbrev: Returns a hash of unambiguous abbreviations for elements.
  *  - #pack: Packs the elements into a binary sequence.
  *  - #sum: Returns a sum of elements according to either <tt>+</tt> or a given block.
  */
@@ -8806,6 +8856,8 @@ rb_ary_deconstruct(VALUE ary)
 void
 Init_Array(void)
 {
+    fake_ary_flags = init_fake_ary_flags();
+
     rb_cArray  = rb_define_class("Array", rb_cObject);
     rb_include_module(rb_cArray, rb_mEnumerable);
 
@@ -8830,8 +8882,6 @@ Init_Array(void)
     rb_define_method(rb_cArray, "[]=", rb_ary_aset, -1);
     rb_define_method(rb_cArray, "at", rb_ary_at, 1);
     rb_define_method(rb_cArray, "fetch", rb_ary_fetch, -1);
-    rb_define_method(rb_cArray, "first", rb_ary_first, -1);
-    rb_define_method(rb_cArray, "last", rb_ary_last, -1);
     rb_define_method(rb_cArray, "concat", rb_ary_concat_multi, -1);
     rb_define_method(rb_cArray, "union", rb_ary_union_multi, -1);
     rb_define_method(rb_cArray, "difference", rb_ary_difference_multi, -1);
@@ -8851,6 +8901,9 @@ Init_Array(void)
     rb_define_method(rb_cArray, "length", rb_ary_length, 0);
     rb_define_method(rb_cArray, "size", rb_ary_length, 0);
     rb_define_method(rb_cArray, "empty?", rb_ary_empty_p, 0);
+    rb_define_method(rb_cArray, "find", rb_ary_find, -1);
+    rb_define_method(rb_cArray, "detect", rb_ary_find, -1);
+    rb_define_method(rb_cArray, "rfind", rb_ary_rfind, -1);
     rb_define_method(rb_cArray, "find_index", rb_ary_index, -1);
     rb_define_method(rb_cArray, "index", rb_ary_index, -1);
     rb_define_method(rb_cArray, "rindex", rb_ary_rindex, -1);
@@ -8928,8 +8981,12 @@ Init_Array(void)
     rb_define_method(rb_cArray, "one?", rb_ary_one_p, -1);
     rb_define_method(rb_cArray, "dig", rb_ary_dig, -1);
     rb_define_method(rb_cArray, "sum", rb_ary_sum, -1);
+    rb_define_method(rb_cArray, "freeze", rb_ary_freeze, 0);
 
     rb_define_method(rb_cArray, "deconstruct", rb_ary_deconstruct, 0);
+
+    rb_cArray_empty_frozen = RB_OBJ_SET_SHAREABLE(rb_ary_freeze(rb_ary_new()));
+    rb_vm_register_global_object(rb_cArray_empty_frozen);
 }
 
 #include "array.rbinc"
diff --git a/array.rb b/array.rb
index b9fa9844e6..81beff0b1c 100644
--- a/array.rb
+++ b/array.rb
@@ -1,62 +1,97 @@
 class Array
   # call-seq:
-  #    array.shuffle!(random: Random) -> array
+  #   shuffle!(random: Random) -> self
   #
-  # Shuffles the elements of +self+ in place.
-  #    a = [1, 2, 3] #=> [1, 2, 3]
-  #    a.shuffle!    #=> [2, 3, 1]
-  #    a             #=> [2, 3, 1]
+  # Shuffles all elements in +self+ into a random order,
+  # as selected by the object given by the keyword argument +random+.
+  # Returns +self+:
   #
-  # The optional +random+ argument will be used as the random number generator:
-  #    a.shuffle!(random: Random.new(1))  #=> [1, 3, 2]
+  #   a =             [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+  #   a.shuffle! # => [5, 3, 8, 7, 6, 1, 9, 4, 2, 0]
+  #   a.shuffle! # => [9, 4, 0, 6, 2, 8, 1, 5, 3, 7]
+  #
+  # Duplicate elements are included:
+  #
+  #   a =             [0, 1, 0, 1, 0, 1, 0, 1, 0, 1]
+  #   a.shuffle! # => [1, 0, 0, 1, 1, 0, 1, 0, 0, 1]
+  #   a.shuffle! # => [0, 1, 0, 1, 1, 0, 1, 0, 1, 0]
+  #
+  # The object given with the keyword argument +random+ is used as the random number generator.
+  #
+  # Related: see {Methods for Assigning}[rdoc-ref:Array@Methods+for+Assigning].
   def shuffle!(random: Random)
     Primitive.rb_ary_shuffle_bang(random)
   end
 
   # call-seq:
-  #    array.shuffle(random: Random) -> new_ary
+  #   shuffle(random: Random) -> new_array
+  #
+  # Returns a new array containing all elements from +self+ in a random order,
+  # as selected by the object given by the keyword argument +random+:
+  #
+  #   a =            [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+  #   a.shuffle # => [0, 8, 1, 9, 6, 3, 4, 7, 2, 5]
+  #   a.shuffle # => [8, 9, 0, 5, 1, 2, 6, 4, 7, 3]
   #
-  # Returns a new array with elements of +self+ shuffled.
-  #    a = [1, 2, 3] #=> [1, 2, 3]
-  #    a.shuffle     #=> [2, 3, 1]
-  #    a             #=> [1, 2, 3]
+  # Duplicate elements are included:
   #
-  # The optional +random+ argument will be used as the random number generator:
-  #    a.shuffle(random: Random.new(1))  #=> [1, 3, 2]
+  #   a =            [0, 1, 0, 1, 0, 1, 0, 1, 0, 1]
+  #   a.shuffle # => [1, 0, 1, 1, 0, 0, 1, 0, 0, 1]
+  #   a.shuffle # => [1, 1, 0, 0, 0, 1, 1, 0, 0, 1]
+  #
+  # The object given with the keyword argument +random+ is used as the random number generator.
+  #
+  # Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
   def shuffle(random: Random)
     Primitive.rb_ary_shuffle(random)
   end
 
   # call-seq:
-  #    array.sample(random: Random) -> object
-  #    array.sample(n, random: Random) -> new_ary
+  #   sample(random: Random) -> object
+  #   sample(count, random: Random) -> new_ary
   #
-  # Returns random elements from +self+.
+  # Returns random elements from +self+,
+  # as selected by the object given by the keyword argument +random+.
   #
-  # When no arguments are given, returns a random element from +self+:
-  #    a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
-  #    a.sample # => 3
-  #    a.sample # => 8
-  # If +self+ is empty, returns +nil+.
+  # With no argument +count+ given, returns one random element from +self+:
+  #
+  #   a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+  #   a.sample # => 3
+  #   a.sample # => 8
+  #
+  # Returns +nil+ if +self+ is empty:
+  #
+  #   [].sample # => nil
+  #
+  # With a non-negative numeric argument +count+ given,
+  # returns a new array containing +count+ random elements from +self+:
+  #
+  #   a.sample(3) # => [8, 9, 2]
+  #   a.sample(6) # => [9, 6, 0, 3, 1, 4]
+  #
+  # The order of the result array is unrelated to the order of +self+.
+  #
+  # Returns a new empty array if +self+ is empty:
+  #
+  #   [].sample(4) # => []
+  #
+  # May return duplicates in +self+:
+  #
+  #   a = [1, 1, 1, 2, 2, 3]
+  #   a.sample(a.size) # => [1, 1, 3, 2, 1, 2]
   #
-  # When argument +n+ is given, returns a new \Array containing +n+ random
-  # elements from +self+:
-  #    a.sample(3) # => [8, 9, 2]
-  #    a.sample(6) # => [9, 6, 10, 3, 1, 4]
   # Returns no more than <tt>a.size</tt> elements
   # (because no new duplicates are introduced):
-  #    a.sample(a.size * 2) # => [6, 4, 1, 8, 5, 9, 10, 2, 3, 7]
-  # But +self+ may contain duplicates:
-  #    a = [1, 1, 1, 2, 2, 3]
-  #    a.sample(a.size * 2) # => [1, 1, 3, 2, 1, 2]
-  # The argument +n+ must be a non-negative numeric value.
-  # The order of the result array is unrelated to the order of +self+.
-  # Returns a new empty \Array if +self+ is empty.
   #
-  # The optional +random+ argument will be used as the random number generator:
-  #    a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
-  #    a.sample(random: Random.new(1))     #=> 6
-  #    a.sample(4, random: Random.new(1))  #=> [6, 10, 9, 2]
+  #   a.sample(50) # => [6, 4, 1, 8, 5, 9, 0, 2, 3, 7]
+  #
+  # The object given with the keyword argument +random+ is used as the random number generator:
+  #
+  #   a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+  #   a.sample(random: Random.new(1))     # => 6
+  #   a.sample(4, random: Random.new(1))  # => [6, 10, 9, 2]
+  #
+  # Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
   def sample(n = (ary = false), random: Random)
     if Primitive.mandatory_only?
       # Primitive.cexpr! %{ rb_ary_sample(self, rb_cRandom, Qfalse, Qfalse) }
@@ -66,4 +101,187 @@ class Array
       Primitive.ary_sample(random, n, ary)
     end
   end
+
+  # call-seq:
+  #   first -> object or nil
+  #   first(count) -> new_array
+  #
+  # Returns elements from +self+, or +nil+; does not modify +self+.
+  #
+  # With no argument given, returns the first element (if available):
+  #
+  #   a = [:foo, 'bar', 2]
+  #   a.first # => :foo
+  #   a # => [:foo, "bar", 2]
+  #
+  # If +self+ is empty, returns +nil+.
+  #
+  #   [].first # => nil
+  #
+  # With a non-negative integer argument +count+ given,
+  # returns the first +count+ elements (as available) in a new array:
+  #
+  #   a.first(0)  # => []
+  #   a.first(2)  # => [:foo, "bar"]
+  #   a.first(50) # => [:foo, "bar", 2]
+  #
+  # Related: see {Methods for Querying}[rdoc-ref:Array@Methods+for+Querying].
+  def first n = unspecified = true
+    if Primitive.mandatory_only?
+      Primitive.attr! :leaf
+      Primitive.cexpr! %q{ ary_first(self) }
+    else
+      if unspecified
+        Primitive.cexpr! %q{ ary_first(self) }
+      else
+        Primitive.cexpr! %q{  ary_take_first_or_last_n(self, NUM2LONG(n), ARY_TAKE_FIRST) }
+      end
+    end
+  end
+
+  # call-seq:
+  #  last  -> last_object or nil
+  #  last(count) -> new_array
+  #
+  # Returns elements from +self+, or +nil+; +self+ is not modified.
+  #
+  # With no argument given, returns the last element, or +nil+ if +self+ is empty:
+  #
+  #   a = [:foo, 'bar', 2]
+  #   a.last # => 2
+  #   a # => [:foo, "bar", 2]
+  #   [].last # => nil
+  #
+  #
+  # With non-negative integer argument +count+ given,
+  # returns a new array containing the trailing +count+ elements of +self+, as available:
+  #
+  #   a = [:foo, 'bar', 2]
+  #   a.last(2)  # => ["bar", 2]
+  #   a.last(50) # => [:foo, "bar", 2]
+  #   a.last(0)  # => []
+  #   [].last(3) # => []
+  #
+  # Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
+  def last n = unspecified = true
+    if Primitive.mandatory_only?
+      Primitive.attr! :leaf
+      Primitive.cexpr! %q{ ary_last(self) }
+    else
+      if unspecified
+        Primitive.cexpr! %q{ ary_last(self) }
+      else
+        Primitive.cexpr! %q{ ary_take_first_or_last_n(self, NUM2LONG(n), ARY_TAKE_LAST) }
+      end
+    end
+  end
+
+  # call-seq:
+  #   fetch_values(*indexes) -> new_array
+  #   fetch_values(*indexes) { |index| ... } -> new_array
+  #
+  # With no block given, returns a new array containing the elements of +self+
+  # at the offsets specified by +indexes+. Each of the +indexes+ must be an
+  # {integer-convertible object}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects]:
+  #
+  #    a = [:foo, :bar, :baz]
+  #    a.fetch_values(2, 0)   # => [:baz, :foo]
+  #    a.fetch_values(2.1, 0) # => [:baz, :foo]
+  #    a.fetch_values         # => []
+  #
+  # For a negative index, counts backwards from the end of the array:
+  #
+  #    a.fetch_values(-2, -1) # [:bar, :baz]
+  #
+  # When no block is given, raises an exception if any index is out of range.
+  #
+  # With a block given, for each index:
+  #
+  # - If the index is in range, uses an element of +self+ (as above).
+  # - Otherwise, calls the block with the index and uses the block's return value.
+  #
+  # Example:
+  #
+  #   a = [:foo, :bar, :baz]
+  #   a.fetch_values(1, 0, 42, 777) { |index| index.to_s }
+  #   # => [:bar, :foo, "42", "777"]
+  #
+  # Related: see {Methods for Fetching}[rdoc-ref:Array@Methods+for+Fetching].
+  def fetch_values(*indexes, &block)
+    indexes.map! { |i| fetch(i, &block) }
+    indexes
+  end
+
+  with_jit do
+    if Primitive.rb_builtin_basic_definition_p(:each)
+      undef :each
+
+      def each # :nodoc:
+        Primitive.attr! :inline_block, :c_trace
+
+        unless defined?(yield)
+          return Primitive.cexpr! 'SIZED_ENUMERATOR(self, 0, 0, ary_enum_length)'
+        end
+        _i = 0
+        value = nil
+        while Primitive.cexpr!(%q{ ary_fetch_next(self, LOCAL_PTR(_i), LOCAL_PTR(value)) })
+          yield value
+        end
+        self
+      end
+    end
+
+    if Primitive.rb_builtin_basic_definition_p(:map)
+      undef :map
+
+      def map # :nodoc:
+        Primitive.attr! :inline_block, :c_trace
+
+        unless defined?(yield)
+          return Primitive.cexpr! 'SIZED_ENUMERATOR(self, 0, 0, ary_enum_length)'
+        end
+
+        _i = 0
+        value = nil
+        result = Primitive.ary_sized_alloc
+        while Primitive.cexpr!(%q{ ary_fetch_next(self, LOCAL_PTR(_i), LOCAL_PTR(value)) })
+          value = yield(value)
+          Primitive.cexpr!(%q{ rb_ary_push(result, value) })
+        end
+        result
+      end
+
+      if Primitive.rb_builtin_basic_definition_p(:collect)
+        undef :collect
+        alias collect map
+      end
+    end
+
+    if Primitive.rb_builtin_basic_definition_p(:select)
+      undef :select
+
+      def select # :nodoc:
+        Primitive.attr! :inline_block, :c_trace
+
+        unless defined?(yield)
+          return Primitive.cexpr! 'SIZED_ENUMERATOR(self, 0, 0, ary_enum_length)'
+        end
+
+        _i = 0
+        value = nil
+        result = Primitive.ary_sized_alloc
+        while Primitive.cexpr!(%q{ ary_fetch_next(self, LOCAL_PTR(_i), LOCAL_PTR(value)) })
+          if yield value
+            Primitive.cexpr!(%q{ rb_ary_push(result, value) })
+          end
+        end
+        result
+      end
+
+      if Primitive.rb_builtin_basic_definition_p(:filter)
+        undef :filter
+        alias filter select
+      end
+    end
+  end
 end
diff --git a/ast.c b/ast.c
index 42d4126a5b..5357aa38a5 100644
--- a/ast.c
+++ b/ast.c
@@ -1,6 +1,6 @@
 /* indent-tabs-mode: nil */
 #include "internal.h"
-#include "internal/parse.h"
+#include "internal/ruby_parser.h"
 #include "internal/symbol.h"
 #include "internal/warnings.h"
 #include "iseq.h"
@@ -14,9 +14,10 @@
 
 static VALUE rb_mAST;
 static VALUE rb_cNode;
+static VALUE rb_cLocation;
 
 struct ASTNodeData {
-    rb_ast_t *ast;
+    VALUE ast_value;
     const NODE *node;
 };
 
@@ -24,14 +25,20 @@ static void
 node_gc_mark(void *ptr)
 {
     struct ASTNodeData *data = (struct ASTNodeData *)ptr;
-    rb_gc_mark((VALUE)data->ast);
+    rb_gc_mark(data->ast_value);
 }
 
 static size_t
 node_memsize(const void *ptr)
 {
     struct ASTNodeData *data = (struct ASTNodeData *)ptr;
-    return rb_ast_memsize(data->ast);
+    size_t size = sizeof(struct ASTNodeData);
+    if (data->ast_value) {
+        rb_ast_t *ast = rb_ruby_ast_data_get(data->ast_value);
+        size += rb_ast_memsize(ast);
+    }
+
+    return size;
 }
 
 static const rb_data_type_t rb_node_type = {
@@ -41,31 +48,57 @@ static const rb_data_type_t rb_node_type = {
     RUBY_TYPED_FREE_IMMEDIATELY,
 };
 
+struct ASTLocationData {
+    int first_lineno;
+    int first_column;
+    int last_lineno;
+    int last_column;
+};
+
+static void
+location_gc_mark(void *ptr)
+{
+}
+
+static size_t
+location_memsize(const void *ptr)
+{
+    return sizeof(struct ASTLocationData);
+}
+
+static const rb_data_type_t rb_location_type = {
+    "AST/location",
+    {location_gc_mark, RUBY_TYPED_DEFAULT_FREE, location_memsize,},
+    0, 0,
+    RUBY_TYPED_FREE_IMMEDIATELY,
+};
+
+
 static VALUE rb_ast_node_alloc(VALUE klass);
 
 static void
-setup_node(VALUE obj, rb_ast_t *ast, const NODE *node)
+setup_node(VALUE obj, VALUE ast_value, const NODE *node)
 {
     struct ASTNodeData *data;
 
     TypedData_Get_Struct(obj, struct ASTNodeData, &rb_node_type, data);
-    data->ast = ast;
+    data->ast_value = ast_value;
     data->node = node;
 }
 
 static VALUE
-ast_new_internal(rb_ast_t *ast, const NODE *node)
+ast_new_internal(VALUE ast_value, const NODE *node)
 {
     VALUE obj;
 
     obj = rb_ast_node_alloc(rb_cNode);
-    setup_node(obj, ast, node);
+    setup_node(obj, ast_value, node);
 
     return obj;
 }
 
-static VALUE rb_ast_parse_str(VALUE str, VALUE keep_script_lines);
-static VALUE rb_ast_parse_file(VALUE path, VALUE keep_script_lines);
+static VALUE rb_ast_parse_str(VALUE str, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens);
+static VALUE rb_ast_parse_file(VALUE path, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens);
 
 static VALUE
 ast_parse_new(void)
@@ -74,83 +107,77 @@ ast_parse_new(void)
 }
 
 static VALUE
-ast_parse_done(rb_ast_t *ast)
+ast_parse_done(VALUE ast_value)
 {
+    rb_ast_t *ast = rb_ruby_ast_data_get(ast_value);
+
     if (!ast->body.root) {
         rb_ast_dispose(ast);
         rb_exc_raise(GET_EC()->errinfo);
     }
 
-    return ast_new_internal(ast, (NODE *)ast->body.root);
+    return ast_new_internal(ast_value, (NODE *)ast->body.root);
 }
 
 static VALUE
-ast_s_parse(rb_execution_context_t *ec, VALUE module, VALUE str, VALUE keep_script_lines)
+setup_vparser(VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
-    return rb_ast_parse_str(str, keep_script_lines);
+    VALUE vparser = ast_parse_new();
+    if (RTEST(keep_script_lines)) rb_parser_set_script_lines(vparser);
+    if (RTEST(error_tolerant)) rb_parser_error_tolerant(vparser);
+    if (RTEST(keep_tokens)) rb_parser_keep_tokens(vparser);
+    return vparser;
 }
 
 static VALUE
-rb_ast_parse_str(VALUE str, VALUE keep_script_lines)
+ast_s_parse(rb_execution_context_t *ec, VALUE module, VALUE str, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
-    rb_ast_t *ast = 0;
+    return rb_ast_parse_str(str, keep_script_lines, error_tolerant, keep_tokens);
+}
 
+static VALUE
+rb_ast_parse_str(VALUE str, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
+{
+    VALUE ast_value = Qnil;
     StringValue(str);
-    VALUE vparser = ast_parse_new();
-    if (RTEST(keep_script_lines)) rb_parser_keep_script_lines(vparser);
-    ast = rb_parser_compile_string_path(vparser, Qnil, str, 1);
-    return ast_parse_done(ast);
+    VALUE vparser = setup_vparser(keep_script_lines, error_tolerant, keep_tokens);
+    ast_value = rb_parser_compile_string_path(vparser, Qnil, str, 1);
+    return ast_parse_done(ast_value);
 }
 
 static VALUE
-ast_s_parse_file(rb_execution_context_t *ec, VALUE module, VALUE path, VALUE keep_script_lines)
+ast_s_parse_file(rb_execution_context_t *ec, VALUE module, VALUE path, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
-    return rb_ast_parse_file(path, keep_script_lines);
+    return rb_ast_parse_file(path, keep_script_lines, error_tolerant, keep_tokens);
 }
 
 static VALUE
-rb_ast_parse_file(VALUE path, VALUE keep_script_lines)
+rb_ast_parse_file(VALUE path, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
     VALUE f;
-    rb_ast_t *ast = 0;
+    VALUE ast_value = Qnil;
     rb_encoding *enc = rb_utf8_encoding();
 
-    FilePathValue(path);
     f = rb_file_open_str(path, "r");
     rb_funcall(f, rb_intern("set_encoding"), 2, rb_enc_from_encoding(enc), rb_str_new_cstr("-"));
-    VALUE vparser = ast_parse_new();
-    if (RTEST(keep_script_lines)) rb_parser_keep_script_lines(vparser);
-    ast = rb_parser_compile_file_path(vparser, Qnil, f, 1);
+    VALUE vparser = setup_vparser(keep_script_lines, error_tolerant, keep_tokens);
+    ast_value = rb_parser_compile_file_path(vparser, Qnil, f, 1);
     rb_io_close(f);
-    return ast_parse_done(ast);
+    return ast_parse_done(ast_value);
 }
 
 static VALUE
-lex_array(VALUE array, int index)
+rb_ast_parse_array(VALUE array, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
-    VALUE str = rb_ary_entry(array, index);
-    if (!NIL_P(str)) {
-        StringValue(str);
-        if (!rb_enc_asciicompat(rb_enc_get(str))) {
-            rb_raise(rb_eArgError, "invalid source encoding");
-        }
-    }
-    return str;
-}
-
-static VALUE
-rb_ast_parse_array(VALUE array, VALUE keep_script_lines)
-{
-    rb_ast_t *ast = 0;
+    VALUE ast_value = Qnil;
 
     array = rb_check_array_type(array);
-    VALUE vparser = ast_parse_new();
-    if (RTEST(keep_script_lines)) rb_parser_keep_script_lines(vparser);
-    ast = rb_parser_compile_generic(vparser, lex_array, Qnil, array, 1);
-    return ast_parse_done(ast);
+    VALUE vparser = setup_vparser(keep_script_lines, error_tolerant, keep_tokens);
+    ast_value = rb_parser_compile_array(vparser, Qnil, array, 1);
+    return ast_parse_done(ast_value);
 }
 
-static VALUE node_children(rb_ast_t*, const NODE*);
+static VALUE node_children(VALUE, const NODE*);
 
 static VALUE
 node_find(VALUE self, const int node_id)
@@ -162,7 +189,7 @@ node_find(VALUE self, const int node_id)
 
     if (nd_node_id(data->node) == node_id) return self;
 
-    ary = node_children(data->ast, data->node);
+    ary = node_children(data->ast_value, data->node);
 
     for (i = 0; i < RARRAY_LEN(ary); i++) {
         VALUE child = RARRAY_AREF(ary, i);
@@ -179,21 +206,24 @@ node_find(VALUE self, const int node_id)
 extern VALUE rb_e_script;
 
 static VALUE
-script_lines(VALUE path)
+node_id_for_backtrace_location(rb_execution_context_t *ec, VALUE module, VALUE location)
 {
-    VALUE hash, lines;
-    ID script_lines;
-    CONST_ID(script_lines, "SCRIPT_LINES__");
-    if (!rb_const_defined_at(rb_cObject, script_lines)) return Qnil;
-    hash = rb_const_get_at(rb_cObject, script_lines);
-    if (!RB_TYPE_P(hash, T_HASH)) return Qnil;
-    lines = rb_hash_lookup(hash, path);
-    if (!RB_TYPE_P(lines, T_ARRAY)) return Qnil;
-    return lines;
+    int node_id;
+
+    if (!rb_frame_info_p(location)) {
+        rb_raise(rb_eTypeError, "Thread::Backtrace::Location object expected");
+    }
+
+    node_id = rb_get_node_id_from_frame_info(location);
+    if (node_id == -1) {
+        return Qnil;
+    }
+
+    return INT2NUM(node_id);
 }
 
 static VALUE
-ast_s_of(rb_execution_context_t *ec, VALUE module, VALUE body, VALUE keep_script_lines)
+ast_s_of(rb_execution_context_t *ec, VALUE module, VALUE body, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
     VALUE node, lines = Qnil;
     const rb_iseq_t *iseq;
@@ -222,6 +252,11 @@ ast_s_of(rb_execution_context_t *ec, VALUE module, VALUE body, VALUE keep_script
     if (!iseq) {
         return Qnil;
     }
+
+    if (ISEQ_BODY(iseq)->prism) {
+        rb_raise(rb_eRuntimeError, "cannot get AST for ISEQ compiled by prism");
+    }
+
     lines = ISEQ_BODY(iseq)->variable.script_lines;
 
     VALUE path = rb_iseq_path(iseq);
@@ -231,14 +266,14 @@ ast_s_of(rb_execution_context_t *ec, VALUE module, VALUE body, VALUE keep_script
         rb_raise(rb_eArgError, "cannot get AST for method defined in eval");
     }
 
-    if (!NIL_P(lines) || !NIL_P(lines = script_lines(path))) {
-        node = rb_ast_parse_array(lines, keep_script_lines);
+    if (!NIL_P(lines)) {
+        node = rb_ast_parse_array(lines, keep_script_lines, error_tolerant, keep_tokens);
     }
     else if (e_option) {
-        node = rb_ast_parse_str(rb_e_script, keep_script_lines);
+        node = rb_ast_parse_str(rb_e_script, keep_script_lines, error_tolerant, keep_tokens);
     }
     else {
-        node = rb_ast_parse_file(path, keep_script_lines);
+        node = rb_ast_parse_file(path, keep_script_lines, error_tolerant, keep_tokens);
     }
 
     return node_find(node, node_id);
@@ -277,10 +312,10 @@ ast_node_node_id(rb_execution_context_t *ec, VALUE self)
     return INT2FIX(nd_node_id(data->node));
 }
 
-#define NEW_CHILD(ast, node) node ? ast_new_internal(ast, node) : Qnil
+#define NEW_CHILD(ast_value, node) (node ? ast_new_internal(ast_value, node) : Qnil)
 
 static VALUE
-rb_ary_new_from_node_args(rb_ast_t *ast, long n, ...)
+rb_ary_new_from_node_args(VALUE ast_value, long n, ...)
 {
     va_list ar;
     VALUE ary;
@@ -292,39 +327,57 @@ rb_ary_new_from_node_args(rb_ast_t *ast, long n, ...)
     for (i=0; i<n; i++) {
         NODE *node;
         node = va_arg(ar, NODE *);
-        rb_ary_push(ary, NEW_CHILD(ast, node));
+        rb_ary_push(ary, NEW_CHILD(ast_value, node));
     }
     va_end(ar);
     return ary;
 }
 
 static VALUE
-dump_block(rb_ast_t *ast, const NODE *node)
+dump_block(VALUE ast_value, const struct RNode_BLOCK *node)
 {
     VALUE ary = rb_ary_new();
     do {
-        rb_ary_push(ary, NEW_CHILD(ast, node->nd_head));
+        rb_ary_push(ary, NEW_CHILD(ast_value, node->nd_head));
     } while (node->nd_next &&
         nd_type_p(node->nd_next, NODE_BLOCK) &&
-        (node = node->nd_next, 1));
+        (node = RNODE_BLOCK(node->nd_next), 1));
     if (node->nd_next) {
-        rb_ary_push(ary, NEW_CHILD(ast, node->nd_next));
+        rb_ary_push(ary, NEW_CHILD(ast_value, node->nd_next));
     }
 
     return ary;
 }
 
 static VALUE
-dump_array(rb_ast_t *ast, const NODE *node)
+dump_array(VALUE ast_value, const struct RNode_LIST *node)
 {
     VALUE ary = rb_ary_new();
-    rb_ary_push(ary, NEW_CHILD(ast, node->nd_head));
+    rb_ary_push(ary, NEW_CHILD(ast_value, node->nd_head));
 
     while (node->nd_next && nd_type_p(node->nd_next, NODE_LIST)) {
-        node = node->nd_next;
-        rb_ary_push(ary, NEW_CHILD(ast, node->nd_head));
+        node = RNODE_LIST(node->nd_next);
+        rb_ary_push(ary, NEW_CHILD(ast_value, node->nd_head));
+    }
+    rb_ary_push(ary, NEW_CHILD(ast_value, node->nd_next));
+
+    return ary;
+}
+
+static VALUE
+dump_parser_array(VALUE ast_value, rb_parser_ary_t *p_ary)
+{
+    VALUE ary;
+
+    if (p_ary->data_type != PARSER_ARY_DATA_NODE) {
+        rb_bug("unexpected rb_parser_ary_data_type: %d", p_ary->data_type);
+    }
+
+    ary = rb_ary_new();
+
+    for (long i = 0; i < p_ary->len; i++) {
+        rb_ary_push(ary, NEW_CHILD(ast_value, p_ary->data[i]));
     }
-    rb_ary_push(ary, NEW_CHILD(ast, node->nd_next));
 
     return ary;
 }
@@ -346,305 +399,341 @@ no_name_rest(void)
 }
 
 static VALUE
-rest_arg(rb_ast_t *ast, const NODE *rest_arg)
+rest_arg(VALUE ast_value, const NODE *rest_arg)
 {
-    return NODE_NAMED_REST_P(rest_arg) ? NEW_CHILD(ast, rest_arg) : no_name_rest();
+    return NODE_NAMED_REST_P(rest_arg) ? NEW_CHILD(ast_value, rest_arg) : no_name_rest();
 }
 
 static VALUE
-node_children(rb_ast_t *ast, const NODE *node)
+node_children(VALUE ast_value, const NODE *node)
 {
-    char name[DECIMAL_SIZE_OF_BITS(sizeof(long) * CHAR_BIT) + 2]; /* including '$' */
+    char name[sizeof("$") + DECIMAL_SIZE_OF(long)];
 
     enum node_type type = nd_type(node);
     switch (type) {
       case NODE_BLOCK:
-        return dump_block(ast, node);
+        return dump_block(ast_value, RNODE_BLOCK(node));
       case NODE_IF:
-        return rb_ary_new_from_node_args(ast, 3, node->nd_cond, node->nd_body, node->nd_else);
+        return rb_ary_new_from_node_args(ast_value, 3, RNODE_IF(node)->nd_cond, RNODE_IF(node)->nd_body, RNODE_IF(node)->nd_else);
       case NODE_UNLESS:
-        return rb_ary_new_from_node_args(ast, 3, node->nd_cond, node->nd_body, node->nd_else);
+        return rb_ary_new_from_node_args(ast_value, 3, RNODE_UNLESS(node)->nd_cond, RNODE_UNLESS(node)->nd_body, RNODE_UNLESS(node)->nd_else);
       case NODE_CASE:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_head, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_CASE(node)->nd_head, RNODE_CASE(node)->nd_body);
       case NODE_CASE2:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_head, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_CASE2(node)->nd_head, RNODE_CASE2(node)->nd_body);
       case NODE_CASE3:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_head, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_CASE3(node)->nd_head, RNODE_CASE3(node)->nd_body);
       case NODE_WHEN:
-        return rb_ary_new_from_node_args(ast, 3, node->nd_head, node->nd_body, node->nd_next);
+        return rb_ary_new_from_node_args(ast_value, 3, RNODE_WHEN(node)->nd_head, RNODE_WHEN(node)->nd_body, RNODE_WHEN(node)->nd_next);
       case NODE_IN:
-        return rb_ary_new_from_node_args(ast, 3, node->nd_head, node->nd_body, node->nd_next);
+        return rb_ary_new_from_node_args(ast_value, 3, RNODE_IN(node)->nd_head, RNODE_IN(node)->nd_body, RNODE_IN(node)->nd_next);
       case NODE_WHILE:
       case NODE_UNTIL:
-        return rb_ary_push(rb_ary_new_from_node_args(ast, 2, node->nd_cond, node->nd_body),
-                           RBOOL(node->nd_state));
+        return rb_ary_push(rb_ary_new_from_node_args(ast_value, 2, RNODE_WHILE(node)->nd_cond, RNODE_WHILE(node)->nd_body),
+                           RBOOL(RNODE_WHILE(node)->nd_state));
       case NODE_ITER:
       case NODE_FOR:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_iter, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_ITER(node)->nd_iter, RNODE_ITER(node)->nd_body);
       case NODE_FOR_MASGN:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_var);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_FOR_MASGN(node)->nd_var);
       case NODE_BREAK:
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_BREAK(node)->nd_stts);
       case NODE_NEXT:
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_NEXT(node)->nd_stts);
       case NODE_RETURN:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_stts);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_RETURN(node)->nd_stts);
       case NODE_REDO:
-        return rb_ary_new_from_node_args(ast, 0);
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_RETRY:
-        return rb_ary_new_from_node_args(ast, 0);
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_BEGIN:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_BEGIN(node)->nd_body);
       case NODE_RESCUE:
-        return rb_ary_new_from_node_args(ast, 3, node->nd_head, node->nd_resq, node->nd_else);
+        return rb_ary_new_from_node_args(ast_value, 3, RNODE_RESCUE(node)->nd_head, RNODE_RESCUE(node)->nd_resq, RNODE_RESCUE(node)->nd_else);
       case NODE_RESBODY:
-        return rb_ary_new_from_node_args(ast, 3, node->nd_args, node->nd_body, node->nd_head);
+        return rb_ary_new_from_node_args(ast_value, 4, RNODE_RESBODY(node)->nd_args, RNODE_RESBODY(node)->nd_exc_var, RNODE_RESBODY(node)->nd_body, RNODE_RESBODY(node)->nd_next);
       case NODE_ENSURE:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_head, node->nd_ensr);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_ENSURE(node)->nd_head, RNODE_ENSURE(node)->nd_ensr);
       case NODE_AND:
       case NODE_OR:
         {
             VALUE ary = rb_ary_new();
 
             while (1) {
-                rb_ary_push(ary, NEW_CHILD(ast, node->nd_1st));
-                if (!node->nd_2nd || !nd_type_p(node->nd_2nd, type))
+                rb_ary_push(ary, NEW_CHILD(ast_value, RNODE_AND(node)->nd_1st));
+                if (!RNODE_AND(node)->nd_2nd || !nd_type_p(RNODE_AND(node)->nd_2nd, type))
                     break;
-                node = node->nd_2nd;
+                node = RNODE_AND(node)->nd_2nd;
             }
-            rb_ary_push(ary, NEW_CHILD(ast, node->nd_2nd));
+            rb_ary_push(ary, NEW_CHILD(ast_value, RNODE_AND(node)->nd_2nd));
             return ary;
         }
       case NODE_MASGN:
-        if (NODE_NAMED_REST_P(node->nd_args)) {
-            return rb_ary_new_from_node_args(ast, 3, node->nd_value, node->nd_head, node->nd_args);
+        if (NODE_NAMED_REST_P(RNODE_MASGN(node)->nd_args)) {
+            return rb_ary_new_from_node_args(ast_value, 3, RNODE_MASGN(node)->nd_value, RNODE_MASGN(node)->nd_head, RNODE_MASGN(node)->nd_args);
         }
         else {
-            return rb_ary_new_from_args(3, NEW_CHILD(ast, node->nd_value),
-                                        NEW_CHILD(ast, node->nd_head),
+            return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_MASGN(node)->nd_value),
+                                        NEW_CHILD(ast_value, RNODE_MASGN(node)->nd_head),
                                         no_name_rest());
         }
       case NODE_LASGN:
+        if (NODE_REQUIRED_KEYWORD_P(RNODE_LASGN(node)->nd_value)) {
+            return rb_ary_new_from_args(2, var_name(RNODE_LASGN(node)->nd_vid), ID2SYM(rb_intern("NODE_SPECIAL_REQUIRED_KEYWORD")));
+        }
+        return rb_ary_new_from_args(2, var_name(RNODE_LASGN(node)->nd_vid), NEW_CHILD(ast_value, RNODE_LASGN(node)->nd_value));
       case NODE_DASGN:
+        if (NODE_REQUIRED_KEYWORD_P(RNODE_DASGN(node)->nd_value)) {
+            return rb_ary_new_from_args(2, var_name(RNODE_DASGN(node)->nd_vid), ID2SYM(rb_intern("NODE_SPECIAL_REQUIRED_KEYWORD")));
+        }
+        return rb_ary_new_from_args(2, var_name(RNODE_DASGN(node)->nd_vid), NEW_CHILD(ast_value, RNODE_DASGN(node)->nd_value));
       case NODE_IASGN:
+        return rb_ary_new_from_args(2, var_name(RNODE_IASGN(node)->nd_vid), NEW_CHILD(ast_value, RNODE_IASGN(node)->nd_value));
       case NODE_CVASGN:
+        return rb_ary_new_from_args(2, var_name(RNODE_CVASGN(node)->nd_vid), NEW_CHILD(ast_value, RNODE_CVASGN(node)->nd_value));
       case NODE_GASGN:
-        if (NODE_REQUIRED_KEYWORD_P(node)) {
-            return rb_ary_new_from_args(2, var_name(node->nd_vid), ID2SYM(rb_intern("NODE_SPECIAL_REQUIRED_KEYWORD")));
-        }
-        return rb_ary_new_from_args(2, var_name(node->nd_vid), NEW_CHILD(ast, node->nd_value));
+        return rb_ary_new_from_args(2, var_name(RNODE_GASGN(node)->nd_vid), NEW_CHILD(ast_value, RNODE_GASGN(node)->nd_value));
       case NODE_CDECL:
-        if (node->nd_vid) {
-            return rb_ary_new_from_args(2, ID2SYM(node->nd_vid), NEW_CHILD(ast, node->nd_value));
+        if (RNODE_CDECL(node)->nd_vid) {
+            return rb_ary_new_from_args(2, ID2SYM(RNODE_CDECL(node)->nd_vid), NEW_CHILD(ast_value, RNODE_CDECL(node)->nd_value));
         }
-        return rb_ary_new_from_args(3, NEW_CHILD(ast, node->nd_else), ID2SYM(node->nd_else->nd_mid), NEW_CHILD(ast, node->nd_value));
+        return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_CDECL(node)->nd_else), ID2SYM(RNODE_COLON2(RNODE_CDECL(node)->nd_else)->nd_mid), NEW_CHILD(ast_value, RNODE_CDECL(node)->nd_value));
       case NODE_OP_ASGN1:
-        return rb_ary_new_from_args(4, NEW_CHILD(ast, node->nd_recv),
-                                    ID2SYM(node->nd_mid),
-                                    NEW_CHILD(ast, node->nd_args->nd_head),
-                                    NEW_CHILD(ast, node->nd_args->nd_body));
+        return rb_ary_new_from_args(4, NEW_CHILD(ast_value, RNODE_OP_ASGN1(node)->nd_recv),
+                                    ID2SYM(RNODE_OP_ASGN1(node)->nd_mid),
+                                    NEW_CHILD(ast_value, RNODE_OP_ASGN1(node)->nd_index),
+                                    NEW_CHILD(ast_value, RNODE_OP_ASGN1(node)->nd_rvalue));
       case NODE_OP_ASGN2:
-        return rb_ary_new_from_args(5, NEW_CHILD(ast, node->nd_recv),
-                                    RBOOL(node->nd_next->nd_aid),
-                                    ID2SYM(node->nd_next->nd_vid),
-                                    ID2SYM(node->nd_next->nd_mid),
-                                    NEW_CHILD(ast, node->nd_value));
+        return rb_ary_new_from_args(5, NEW_CHILD(ast_value, RNODE_OP_ASGN2(node)->nd_recv),
+                                    RBOOL(RNODE_OP_ASGN2(node)->nd_aid),
+                                    ID2SYM(RNODE_OP_ASGN2(node)->nd_vid),
+                                    ID2SYM(RNODE_OP_ASGN2(node)->nd_mid),
+                                    NEW_CHILD(ast_value, RNODE_OP_ASGN2(node)->nd_value));
       case NODE_OP_ASGN_AND:
-        return rb_ary_new_from_args(3, NEW_CHILD(ast, node->nd_head), ID2SYM(idANDOP),
-                                    NEW_CHILD(ast, node->nd_value));
+        return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_OP_ASGN_AND(node)->nd_head), ID2SYM(idANDOP),
+                                    NEW_CHILD(ast_value, RNODE_OP_ASGN_AND(node)->nd_value));
       case NODE_OP_ASGN_OR:
-        return rb_ary_new_from_args(3, NEW_CHILD(ast, node->nd_head), ID2SYM(idOROP),
-                                    NEW_CHILD(ast, node->nd_value));
+        return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_OP_ASGN_OR(node)->nd_head), ID2SYM(idOROP),
+                                    NEW_CHILD(ast_value, RNODE_OP_ASGN_OR(node)->nd_value));
       case NODE_OP_CDECL:
-        return rb_ary_new_from_args(3, NEW_CHILD(ast, node->nd_head),
-                                    ID2SYM(node->nd_aid),
-                                    NEW_CHILD(ast, node->nd_value));
+        return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_OP_CDECL(node)->nd_head),
+                                    ID2SYM(RNODE_OP_CDECL(node)->nd_aid),
+                                    NEW_CHILD(ast_value, RNODE_OP_CDECL(node)->nd_value));
       case NODE_CALL:
+        return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_CALL(node)->nd_recv),
+                                    ID2SYM(RNODE_CALL(node)->nd_mid),
+                                    NEW_CHILD(ast_value, RNODE_CALL(node)->nd_args));
       case NODE_OPCALL:
+        return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_OPCALL(node)->nd_recv),
+                                    ID2SYM(RNODE_OPCALL(node)->nd_mid),
+                                    NEW_CHILD(ast_value, RNODE_OPCALL(node)->nd_args));
       case NODE_QCALL:
-        return rb_ary_new_from_args(3, NEW_CHILD(ast, node->nd_recv),
-                                    ID2SYM(node->nd_mid),
-                                    NEW_CHILD(ast, node->nd_args));
+        return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_QCALL(node)->nd_recv),
+                                    ID2SYM(RNODE_QCALL(node)->nd_mid),
+                                    NEW_CHILD(ast_value, RNODE_QCALL(node)->nd_args));
       case NODE_FCALL:
-        return rb_ary_new_from_args(2, ID2SYM(node->nd_mid),
-                                    NEW_CHILD(ast, node->nd_args));
+        return rb_ary_new_from_args(2, ID2SYM(RNODE_FCALL(node)->nd_mid),
+                                    NEW_CHILD(ast_value, RNODE_FCALL(node)->nd_args));
       case NODE_VCALL:
-        return rb_ary_new_from_args(1, ID2SYM(node->nd_mid));
+        return rb_ary_new_from_args(1, ID2SYM(RNODE_VCALL(node)->nd_mid));
       case NODE_SUPER:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_args);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_SUPER(node)->nd_args);
       case NODE_ZSUPER:
-        return rb_ary_new_from_node_args(ast, 0);
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_LIST:
-      case NODE_VALUES:
-        return dump_array(ast, node);
+        return dump_array(ast_value, RNODE_LIST(node));
       case NODE_ZLIST:
-        return rb_ary_new_from_node_args(ast, 0);
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_HASH:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_head);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_HASH(node)->nd_head);
       case NODE_YIELD:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_head);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_YIELD(node)->nd_head);
       case NODE_LVAR:
+        return rb_ary_new_from_args(1, var_name(RNODE_LVAR(node)->nd_vid));
       case NODE_DVAR:
-        return rb_ary_new_from_args(1, var_name(node->nd_vid));
+        return rb_ary_new_from_args(1, var_name(RNODE_DVAR(node)->nd_vid));
       case NODE_IVAR:
+        return rb_ary_new_from_args(1, ID2SYM(RNODE_IVAR(node)->nd_vid));
       case NODE_CONST:
+        return rb_ary_new_from_args(1, ID2SYM(RNODE_CONST(node)->nd_vid));
       case NODE_CVAR:
+        return rb_ary_new_from_args(1, ID2SYM(RNODE_CVAR(node)->nd_vid));
       case NODE_GVAR:
-        return rb_ary_new_from_args(1, ID2SYM(node->nd_vid));
+        return rb_ary_new_from_args(1, ID2SYM(RNODE_GVAR(node)->nd_vid));
       case NODE_NTH_REF:
-        snprintf(name, sizeof(name), "$%ld", node->nd_nth);
+        snprintf(name, sizeof(name), "$%ld", RNODE_NTH_REF(node)->nd_nth);
         return rb_ary_new_from_args(1, ID2SYM(rb_intern(name)));
       case NODE_BACK_REF:
         name[0] = '$';
-        name[1] = (char)node->nd_nth;
+        name[1] = (char)RNODE_BACK_REF(node)->nd_nth;
         name[2] = '\0';
         return rb_ary_new_from_args(1, ID2SYM(rb_intern(name)));
+      case NODE_MATCH:
+        return rb_ary_new_from_args(1, rb_node_regx_string_val(node));
       case NODE_MATCH2:
-        if (node->nd_args) {
-            return rb_ary_new_from_node_args(ast, 3, node->nd_recv, node->nd_value, node->nd_args);
+        if (RNODE_MATCH2(node)->nd_args) {
+            return rb_ary_new_from_node_args(ast_value, 3, RNODE_MATCH2(node)->nd_recv, RNODE_MATCH2(node)->nd_value, RNODE_MATCH2(node)->nd_args);
         }
-        return rb_ary_new_from_node_args(ast, 2, node->nd_recv, node->nd_value);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_MATCH2(node)->nd_recv, RNODE_MATCH2(node)->nd_value);
       case NODE_MATCH3:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_recv, node->nd_value);
-      case NODE_MATCH:
-      case NODE_LIT:
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_MATCH3(node)->nd_recv, RNODE_MATCH3(node)->nd_value);
       case NODE_STR:
       case NODE_XSTR:
-        return rb_ary_new_from_args(1, node->nd_lit);
+        return rb_ary_new_from_args(1, rb_node_str_string_val(node));
+      case NODE_INTEGER:
+        return rb_ary_new_from_args(1, rb_node_integer_literal_val(node));
+      case NODE_FLOAT:
+        return rb_ary_new_from_args(1, rb_node_float_literal_val(node));
+      case NODE_RATIONAL:
+        return rb_ary_new_from_args(1, rb_node_rational_literal_val(node));
+      case NODE_IMAGINARY:
+        return rb_ary_new_from_args(1, rb_node_imaginary_literal_val(node));
+      case NODE_REGX:
+        return rb_ary_new_from_args(1, rb_node_regx_string_val(node));
       case NODE_ONCE:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_ONCE(node)->nd_body);
       case NODE_DSTR:
       case NODE_DXSTR:
       case NODE_DREGX:
       case NODE_DSYM:
         {
-            NODE *n = node->nd_next;
+            struct RNode_LIST *n = RNODE_DSTR(node)->nd_next;
             VALUE head = Qnil, next = Qnil;
             if (n) {
-                head = NEW_CHILD(ast, n->nd_head);
-                next = NEW_CHILD(ast, n->nd_next);
+                head = NEW_CHILD(ast_value, n->nd_head);
+                next = NEW_CHILD(ast_value, n->nd_next);
             }
-            return rb_ary_new_from_args(3, node->nd_lit, head, next);
+            return rb_ary_new_from_args(3, rb_node_dstr_string_val(node), head, next);
         }
+      case NODE_SYM:
+        return rb_ary_new_from_args(1, rb_node_sym_string_val(node));
       case NODE_EVSTR:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_EVSTR(node)->nd_body);
       case NODE_ARGSCAT:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_head, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_ARGSCAT(node)->nd_head, RNODE_ARGSCAT(node)->nd_body);
       case NODE_ARGSPUSH:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_head, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_ARGSPUSH(node)->nd_head, RNODE_ARGSPUSH(node)->nd_body);
       case NODE_SPLAT:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_head);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_SPLAT(node)->nd_head);
       case NODE_BLOCK_PASS:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_head, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_BLOCK_PASS(node)->nd_head, RNODE_BLOCK_PASS(node)->nd_body);
       case NODE_DEFN:
-        return rb_ary_new_from_args(2, ID2SYM(node->nd_mid), NEW_CHILD(ast, node->nd_defn));
+        return rb_ary_new_from_args(2, ID2SYM(RNODE_DEFN(node)->nd_mid), NEW_CHILD(ast_value, RNODE_DEFN(node)->nd_defn));
       case NODE_DEFS:
-        return rb_ary_new_from_args(3, NEW_CHILD(ast, node->nd_recv), ID2SYM(node->nd_mid), NEW_CHILD(ast, node->nd_defn));
+        return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_DEFS(node)->nd_recv), ID2SYM(RNODE_DEFS(node)->nd_mid), NEW_CHILD(ast_value, RNODE_DEFS(node)->nd_defn));
       case NODE_ALIAS:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_1st, node->nd_2nd);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_ALIAS(node)->nd_1st, RNODE_ALIAS(node)->nd_2nd);
       case NODE_VALIAS:
-        return rb_ary_new_from_args(2, ID2SYM(node->nd_alias), ID2SYM(node->nd_orig));
+        return rb_ary_new_from_args(2, ID2SYM(RNODE_VALIAS(node)->nd_alias), ID2SYM(RNODE_VALIAS(node)->nd_orig));
       case NODE_UNDEF:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_undef);
+        return rb_ary_new_from_args(1, dump_parser_array(ast_value, RNODE_UNDEF(node)->nd_undefs));
       case NODE_CLASS:
-        return rb_ary_new_from_node_args(ast, 3, node->nd_cpath, node->nd_super, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 3, RNODE_CLASS(node)->nd_cpath, RNODE_CLASS(node)->nd_super, RNODE_CLASS(node)->nd_body);
       case NODE_MODULE:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_cpath, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_MODULE(node)->nd_cpath, RNODE_MODULE(node)->nd_body);
       case NODE_SCLASS:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_recv, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_SCLASS(node)->nd_recv, RNODE_SCLASS(node)->nd_body);
       case NODE_COLON2:
-        return rb_ary_new_from_args(2, NEW_CHILD(ast, node->nd_head), ID2SYM(node->nd_mid));
+        return rb_ary_new_from_args(2, NEW_CHILD(ast_value, RNODE_COLON2(node)->nd_head), ID2SYM(RNODE_COLON2(node)->nd_mid));
       case NODE_COLON3:
-        return rb_ary_new_from_args(1, ID2SYM(node->nd_mid));
+        return rb_ary_new_from_args(1, ID2SYM(RNODE_COLON3(node)->nd_mid));
       case NODE_DOT2:
       case NODE_DOT3:
       case NODE_FLIP2:
       case NODE_FLIP3:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_beg, node->nd_end);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_DOT2(node)->nd_beg, RNODE_DOT2(node)->nd_end);
       case NODE_SELF:
-        return rb_ary_new_from_node_args(ast, 0);
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_NIL:
-        return rb_ary_new_from_node_args(ast, 0);
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_TRUE:
-        return rb_ary_new_from_node_args(ast, 0);
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_FALSE:
-        return rb_ary_new_from_node_args(ast, 0);
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_ERRINFO:
-        return rb_ary_new_from_node_args(ast, 0);
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_DEFINED:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_head);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_DEFINED(node)->nd_head);
       case NODE_POSTEXE:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_POSTEXE(node)->nd_body);
       case NODE_ATTRASGN:
-        return rb_ary_new_from_args(3, NEW_CHILD(ast, node->nd_recv), ID2SYM(node->nd_mid), NEW_CHILD(ast, node->nd_args));
+        return rb_ary_new_from_args(3, NEW_CHILD(ast_value, RNODE_ATTRASGN(node)->nd_recv), ID2SYM(RNODE_ATTRASGN(node)->nd_mid), NEW_CHILD(ast_value, RNODE_ATTRASGN(node)->nd_args));
       case NODE_LAMBDA:
-        return rb_ary_new_from_node_args(ast, 1, node->nd_body);
+        return rb_ary_new_from_node_args(ast_value, 1, RNODE_LAMBDA(node)->nd_body);
       case NODE_OPT_ARG:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_body, node->nd_next);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_OPT_ARG(node)->nd_body, RNODE_OPT_ARG(node)->nd_next);
       case NODE_KW_ARG:
-        return rb_ary_new_from_node_args(ast, 2, node->nd_body, node->nd_next);
+        return rb_ary_new_from_node_args(ast_value, 2, RNODE_KW_ARG(node)->nd_body, RNODE_KW_ARG(node)->nd_next);
       case NODE_POSTARG:
-        if (NODE_NAMED_REST_P(node->nd_1st)) {
-            return rb_ary_new_from_node_args(ast, 2, node->nd_1st, node->nd_2nd);
+        if (NODE_NAMED_REST_P(RNODE_POSTARG(node)->nd_1st)) {
+            return rb_ary_new_from_node_args(ast_value, 2, RNODE_POSTARG(node)->nd_1st, RNODE_POSTARG(node)->nd_2nd);
         }
         return rb_ary_new_from_args(2, no_name_rest(),
-                                    NEW_CHILD(ast, node->nd_2nd));
+                                    NEW_CHILD(ast_value, RNODE_POSTARG(node)->nd_2nd));
       case NODE_ARGS:
         {
-            struct rb_args_info *ainfo = node->nd_ainfo;
+            struct rb_args_info *ainfo = &RNODE_ARGS(node)->nd_ainfo;
             return rb_ary_new_from_args(10,
                                         INT2NUM(ainfo->pre_args_num),
-                                        NEW_CHILD(ast, ainfo->pre_init),
-                                        NEW_CHILD(ast, ainfo->opt_args),
+                                        NEW_CHILD(ast_value, ainfo->pre_init),
+                                        NEW_CHILD(ast_value, (NODE *)ainfo->opt_args),
                                         var_name(ainfo->first_post_arg),
                                         INT2NUM(ainfo->post_args_num),
-                                        NEW_CHILD(ast, ainfo->post_init),
+                                        NEW_CHILD(ast_value, ainfo->post_init),
                                         (ainfo->rest_arg == NODE_SPECIAL_EXCESSIVE_COMMA
                                             ? ID2SYM(rb_intern("NODE_SPECIAL_EXCESSIVE_COMMA"))
                                             : var_name(ainfo->rest_arg)),
-                                        (ainfo->no_kwarg ? Qfalse : NEW_CHILD(ast, ainfo->kw_args)),
-                                        (ainfo->no_kwarg ? Qfalse : NEW_CHILD(ast, ainfo->kw_rest_arg)),
+                                        (ainfo->no_kwarg ? Qfalse : NEW_CHILD(ast_value, (NODE *)ainfo->kw_args)),
+                                        (ainfo->no_kwarg ? Qfalse : NEW_CHILD(ast_value, ainfo->kw_rest_arg)),
                                         var_name(ainfo->block_arg));
         }
       case NODE_SCOPE:
         {
-            rb_ast_id_table_t *tbl = node->nd_tbl;
+            rb_ast_id_table_t *tbl = RNODE_SCOPE(node)->nd_tbl;
             int i, size = tbl ? tbl->size : 0;
             VALUE locals = rb_ary_new_capa(size);
             for (i = 0; i < size; i++) {
                 rb_ary_push(locals, var_name(tbl->ids[i]));
             }
-            return rb_ary_new_from_args(3, locals, NEW_CHILD(ast, node->nd_args), NEW_CHILD(ast, node->nd_body));
+            return rb_ary_new_from_args(3, locals, NEW_CHILD(ast_value, (NODE *)RNODE_SCOPE(node)->nd_args), NEW_CHILD(ast_value, RNODE_SCOPE(node)->nd_body));
         }
       case NODE_ARYPTN:
         {
-            struct rb_ary_pattern_info *apinfo = node->nd_apinfo;
-            VALUE rest = rest_arg(ast, apinfo->rest_arg);
+            VALUE rest = rest_arg(ast_value, RNODE_ARYPTN(node)->rest_arg);
             return rb_ary_new_from_args(4,
-                                        NEW_CHILD(ast, node->nd_pconst),
-                                        NEW_CHILD(ast, apinfo->pre_args),
+                                        NEW_CHILD(ast_value, RNODE_ARYPTN(node)->nd_pconst),
+                                        NEW_CHILD(ast_value, RNODE_ARYPTN(node)->pre_args),
                                         rest,
-                                        NEW_CHILD(ast, apinfo->post_args));
+                                        NEW_CHILD(ast_value, RNODE_ARYPTN(node)->post_args));
         }
       case NODE_FNDPTN:
         {
-            struct rb_fnd_pattern_info *fpinfo = node->nd_fpinfo;
-            VALUE pre_rest = rest_arg(ast, fpinfo->pre_rest_arg);
-            VALUE post_rest = rest_arg(ast, fpinfo->post_rest_arg);
+            VALUE pre_rest = rest_arg(ast_value, RNODE_FNDPTN(node)->pre_rest_arg);
+            VALUE post_rest = rest_arg(ast_value, RNODE_FNDPTN(node)->post_rest_arg);
             return rb_ary_new_from_args(4,
-                                        NEW_CHILD(ast, node->nd_pconst),
+                                        NEW_CHILD(ast_value, RNODE_FNDPTN(node)->nd_pconst),
                                         pre_rest,
-                                        NEW_CHILD(ast, fpinfo->args),
+                                        NEW_CHILD(ast_value, RNODE_FNDPTN(node)->args),
                                         post_rest);
         }
       case NODE_HSHPTN:
         {
-            VALUE kwrest = node->nd_pkwrestarg == NODE_SPECIAL_NO_REST_KEYWORD ? ID2SYM(rb_intern("NODE_SPECIAL_NO_REST_KEYWORD")) :
-                                                                                 NEW_CHILD(ast, node->nd_pkwrestarg);
+            VALUE kwrest = RNODE_HSHPTN(node)->nd_pkwrestarg == NODE_SPECIAL_NO_REST_KEYWORD ? ID2SYM(rb_intern("NODE_SPECIAL_NO_REST_KEYWORD")) :
+                                                                                 NEW_CHILD(ast_value, RNODE_HSHPTN(node)->nd_pkwrestarg);
 
             return rb_ary_new_from_args(3,
-                                        NEW_CHILD(ast, node->nd_pconst),
-                                        NEW_CHILD(ast, node->nd_pkwargs),
+                                        NEW_CHILD(ast_value, RNODE_HSHPTN(node)->nd_pconst),
+                                        NEW_CHILD(ast_value, RNODE_HSHPTN(node)->nd_pkwargs),
                                         kwrest);
         }
+      case NODE_LINE:
+        return rb_ary_new_from_args(1, rb_node_line_lineno_val(node));
+      case NODE_FILE:
+        return rb_ary_new_from_args(1, rb_node_file_path_val(node));
+      case NODE_ENCODING:
+        return rb_ary_new_from_args(1, rb_node_encoding_val(node));
+      case NODE_ERROR:
+        return rb_ary_new_from_node_args(ast_value, 0);
       case NODE_ARGS_AUX:
       case NODE_LAST:
         break;
@@ -659,7 +748,250 @@ ast_node_children(rb_execution_context_t *ec, VALUE self)
     struct ASTNodeData *data;
     TypedData_Get_Struct(self, struct ASTNodeData, &rb_node_type, data);
 
-    return node_children(data->ast, data->node);
+    return node_children(data->ast_value, data->node);
+}
+
+static int
+null_loc_p(rb_code_location_t *loc)
+{
+    return (loc->beg_pos.lineno == 0 && loc->beg_pos.column == -1 && loc->end_pos.lineno == 0 && loc->end_pos.column == -1);
+}
+
+static VALUE
+location_new(rb_code_location_t *loc)
+{
+    VALUE obj;
+    struct ASTLocationData *data;
+
+    if (null_loc_p(loc)) return Qnil;
+
+    obj = TypedData_Make_Struct(rb_cLocation, struct ASTLocationData, &rb_location_type, data);
+    data->first_lineno = loc->beg_pos.lineno;
+    data->first_column = loc->beg_pos.column;
+    data->last_lineno = loc->end_pos.lineno;
+    data->last_column = loc->end_pos.column;
+
+    return obj;
+}
+
+static VALUE
+node_locations(VALUE ast_value, const NODE *node)
+{
+    enum node_type type = nd_type(node);
+    switch (type) {
+      case NODE_ALIAS:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_ALIAS(node)->keyword_loc));
+      case NODE_AND:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_AND(node)->operator_loc));
+      case NODE_BLOCK_PASS:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_BLOCK_PASS(node)->operator_loc));
+      case NODE_BREAK:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_BREAK(node)->keyword_loc));
+      case NODE_CASE:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_CASE(node)->case_keyword_loc),
+                                    location_new(&RNODE_CASE(node)->end_keyword_loc));
+      case NODE_CASE2:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_CASE2(node)->case_keyword_loc),
+                                    location_new(&RNODE_CASE2(node)->end_keyword_loc));
+      case NODE_CASE3:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_CASE3(node)->case_keyword_loc),
+                                    location_new(&RNODE_CASE3(node)->end_keyword_loc));
+      case NODE_CLASS:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_CLASS(node)->class_keyword_loc),
+                                    location_new(&RNODE_CLASS(node)->inheritance_operator_loc),
+                                    location_new(&RNODE_CLASS(node)->end_keyword_loc));
+      case NODE_COLON2:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_COLON2(node)->delimiter_loc),
+                                    location_new(&RNODE_COLON2(node)->name_loc));
+      case NODE_COLON3:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_COLON3(node)->delimiter_loc),
+                                    location_new(&RNODE_COLON3(node)->name_loc));
+      case NODE_DEFINED:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_DEFINED(node)->keyword_loc));
+      case NODE_DOT2:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_DOT2(node)->operator_loc));
+      case NODE_DOT3:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_DOT3(node)->operator_loc));
+      case NODE_EVSTR:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_EVSTR(node)->opening_loc),
+                                    location_new(&RNODE_EVSTR(node)->closing_loc));
+      case NODE_FLIP2:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_FLIP2(node)->operator_loc));
+      case NODE_FLIP3:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_FLIP3(node)->operator_loc));
+      case NODE_FOR:
+        return rb_ary_new_from_args(5,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_FOR(node)->for_keyword_loc),
+                                    location_new(&RNODE_FOR(node)->in_keyword_loc),
+                                    location_new(&RNODE_FOR(node)->do_keyword_loc),
+                                    location_new(&RNODE_FOR(node)->end_keyword_loc));
+      case NODE_LAMBDA:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_LAMBDA(node)->operator_loc),
+                                    location_new(&RNODE_LAMBDA(node)->opening_loc),
+                                    location_new(&RNODE_LAMBDA(node)->closing_loc));
+      case NODE_IF:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_IF(node)->if_keyword_loc),
+                                    location_new(&RNODE_IF(node)->then_keyword_loc),
+                                    location_new(&RNODE_IF(node)->end_keyword_loc));
+      case NODE_IN:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_IN(node)->in_keyword_loc),
+                                    location_new(&RNODE_IN(node)->then_keyword_loc),
+                                    location_new(&RNODE_IN(node)->operator_loc));
+      case NODE_MODULE:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_MODULE(node)->module_keyword_loc),
+                                    location_new(&RNODE_MODULE(node)->end_keyword_loc));
+      case NODE_NEXT:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_NEXT(node)->keyword_loc));
+      case NODE_OR:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_OR(node)->operator_loc));
+      case NODE_OP_ASGN1:
+        return rb_ary_new_from_args(5,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_OP_ASGN1(node)->call_operator_loc),
+                                    location_new(&RNODE_OP_ASGN1(node)->opening_loc),
+                                    location_new(&RNODE_OP_ASGN1(node)->closing_loc),
+                                    location_new(&RNODE_OP_ASGN1(node)->binary_operator_loc));
+      case NODE_OP_ASGN2:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_OP_ASGN2(node)->call_operator_loc),
+                                    location_new(&RNODE_OP_ASGN2(node)->message_loc),
+                                    location_new(&RNODE_OP_ASGN2(node)->binary_operator_loc));
+      case NODE_POSTEXE:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_POSTEXE(node)->keyword_loc),
+                                    location_new(&RNODE_POSTEXE(node)->opening_loc),
+                                    location_new(&RNODE_POSTEXE(node)->closing_loc));
+      case NODE_REDO:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_REDO(node)->keyword_loc));
+      case NODE_REGX:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_REGX(node)->opening_loc),
+                                    location_new(&RNODE_REGX(node)->content_loc),
+                                    location_new(&RNODE_REGX(node)->closing_loc));
+      case NODE_RETURN:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_RETURN(node)->keyword_loc));
+
+      case NODE_SCLASS:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_SCLASS(node)->class_keyword_loc),
+                                    location_new(&RNODE_SCLASS(node)->operator_loc),
+                                    location_new(&RNODE_SCLASS(node)->end_keyword_loc));
+
+      case NODE_SPLAT:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_SPLAT(node)->operator_loc));
+      case NODE_SUPER:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_SUPER(node)->keyword_loc),
+                                    location_new(&RNODE_SUPER(node)->lparen_loc),
+                                    location_new(&RNODE_SUPER(node)->rparen_loc));
+      case NODE_UNDEF:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_UNDEF(node)->keyword_loc));
+      case NODE_UNLESS:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_UNLESS(node)->keyword_loc),
+                                    location_new(&RNODE_UNLESS(node)->then_keyword_loc),
+                                    location_new(&RNODE_UNLESS(node)->end_keyword_loc));
+      case NODE_VALIAS:
+        return rb_ary_new_from_args(2,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_VALIAS(node)->keyword_loc));
+      case NODE_WHEN:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_WHEN(node)->keyword_loc),
+                                    location_new(&RNODE_WHEN(node)->then_keyword_loc));
+      case NODE_WHILE:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_WHILE(node)->keyword_loc),
+                                    location_new(&RNODE_WHILE(node)->closing_loc));
+      case NODE_UNTIL:
+        return rb_ary_new_from_args(3,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_UNTIL(node)->keyword_loc),
+                                    location_new(&RNODE_UNTIL(node)->closing_loc));
+      case NODE_YIELD:
+        return rb_ary_new_from_args(4,
+                                    location_new(nd_code_loc(node)),
+                                    location_new(&RNODE_YIELD(node)->keyword_loc),
+                                    location_new(&RNODE_YIELD(node)->lparen_loc),
+                                    location_new(&RNODE_YIELD(node)->rparen_loc));
+      case NODE_ARGS_AUX:
+      case NODE_LAST:
+        break;
+      default:
+        return rb_ary_new_from_args(1, location_new(nd_code_loc(node)));
+    }
+
+    rb_bug("node_locations: unknown node: %s", ruby_node_name(type));
+}
+
+static VALUE
+ast_node_locations(rb_execution_context_t *ec, VALUE self)
+{
+    struct ASTNodeData *data;
+    TypedData_Get_Struct(self, struct ASTNodeData, &rb_node_type, data);
+
+    return node_locations(data->ast_value, data->node);
 }
 
 static VALUE
@@ -699,6 +1031,42 @@ ast_node_last_column(rb_execution_context_t *ec, VALUE self)
 }
 
 static VALUE
+ast_node_all_tokens(rb_execution_context_t *ec, VALUE self)
+{
+    long i;
+    struct ASTNodeData *data;
+    rb_ast_t *ast;
+    rb_parser_ary_t *parser_tokens;
+    rb_parser_ast_token_t *parser_token;
+    VALUE str, loc, token, all_tokens;
+
+    TypedData_Get_Struct(self, struct ASTNodeData, &rb_node_type, data);
+    ast = rb_ruby_ast_data_get(data->ast_value);
+
+    parser_tokens = ast->node_buffer->tokens;
+    if (parser_tokens == NULL) {
+        return Qnil;
+    }
+
+    all_tokens = rb_ary_new2(parser_tokens->len);
+    for (i = 0; i < parser_tokens->len; i++) {
+        parser_token = parser_tokens->data[i];
+        str = rb_str_new(parser_token->str->ptr, parser_token->str->len);
+        loc = rb_ary_new_from_args(4,
+            INT2FIX(parser_token->loc.beg_pos.lineno),
+            INT2FIX(parser_token->loc.beg_pos.column),
+            INT2FIX(parser_token->loc.end_pos.lineno),
+            INT2FIX(parser_token->loc.end_pos.column)
+        );
+        token = rb_ary_new_from_args(4, INT2FIX(parser_token->id), ID2SYM(rb_intern(parser_token->type_name)), str, loc);
+        rb_ary_push(all_tokens, token);
+    }
+    rb_ary_freeze(all_tokens);
+
+    return all_tokens;
+}
+
+static VALUE
 ast_node_inspect(rb_execution_context_t *ec, VALUE self)
 {
     VALUE str;
@@ -722,10 +1090,66 @@ static VALUE
 ast_node_script_lines(rb_execution_context_t *ec, VALUE self)
 {
     struct ASTNodeData *data;
+    rb_ast_t *ast;
     TypedData_Get_Struct(self, struct ASTNodeData, &rb_node_type, data);
-    VALUE ret = data->ast->body.script_lines;
-    if (!RB_TYPE_P(ret, T_ARRAY)) return Qnil;
-    return ret;
+    ast = rb_ruby_ast_data_get(data->ast_value);
+    rb_parser_ary_t *ret = ast->body.script_lines;
+    return rb_parser_build_script_lines_from(ret);
+}
+
+static VALUE
+ast_location_first_lineno(rb_execution_context_t *ec, VALUE self)
+{
+    struct ASTLocationData *data;
+    TypedData_Get_Struct(self, struct ASTLocationData, &rb_location_type, data);
+
+    return INT2NUM(data->first_lineno);
+}
+
+static VALUE
+ast_location_first_column(rb_execution_context_t *ec, VALUE self)
+{
+    struct ASTLocationData *data;
+    TypedData_Get_Struct(self, struct ASTLocationData, &rb_location_type, data);
+
+    return INT2NUM(data->first_column);
+}
+
+static VALUE
+ast_location_last_lineno(rb_execution_context_t *ec, VALUE self)
+{
+    struct ASTLocationData *data;
+    TypedData_Get_Struct(self, struct ASTLocationData, &rb_location_type, data);
+
+    return INT2NUM(data->last_lineno);
+}
+
+static VALUE
+ast_location_last_column(rb_execution_context_t *ec, VALUE self)
+{
+    struct ASTLocationData *data;
+    TypedData_Get_Struct(self, struct ASTLocationData, &rb_location_type, data);
+
+    return INT2NUM(data->last_column);
+}
+
+static VALUE
+ast_location_inspect(rb_execution_context_t *ec, VALUE self)
+{
+    VALUE str;
+    VALUE cname;
+    struct ASTLocationData *data;
+    TypedData_Get_Struct(self, struct ASTLocationData, &rb_location_type, data);
+
+    cname = rb_class_path(rb_obj_class(self));
+    str = rb_str_new2("#<");
+
+    rb_str_append(str, cname);
+    rb_str_catf(str, ":@%d:%d-%d:%d>",
+                data->first_lineno, data->first_column,
+                data->last_lineno, data->last_column);
+
+    return str;
 }
 
 #include "ast.rbinc"
@@ -735,5 +1159,7 @@ Init_ast(void)
 {
     rb_mAST = rb_define_module_under(rb_cRubyVM, "AbstractSyntaxTree");
     rb_cNode = rb_define_class_under(rb_mAST, "Node", rb_cObject);
+    rb_cLocation = rb_define_class_under(rb_mAST, "Location", rb_cObject);
     rb_undef_alloc_func(rb_cNode);
+    rb_undef_alloc_func(rb_cLocation);
 }
diff --git a/ast.rb b/ast.rb
index f866bd23e5..6380621780 100644
--- a/ast.rb
+++ b/ast.rb
@@ -13,28 +13,53 @@
 # access children nodes by name, etc.
 #
 # If you are looking for a stable API or an API working under multiple Ruby
-# implementations, consider using the _parser_ gem or Ripper. If you would
-# like to make RubyVM::AbstractSyntaxTree stable, please join the discussion
-# at https://bugs.ruby-lang.org/issues/14844.
+# implementations, consider using the _prism_ gem, which is the official
+# Ruby API to parse Ruby code.
 #
 module RubyVM::AbstractSyntaxTree
 
   #  call-seq:
-  #     RubyVM::AbstractSyntaxTree.parse(string) -> RubyVM::AbstractSyntaxTree::Node
+  #     RubyVM::AbstractSyntaxTree.parse(string, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false) -> RubyVM::AbstractSyntaxTree::Node
   #
   #  Parses the given _string_ into an abstract syntax tree,
   #  returning the root node of that tree.
   #
-  #  SyntaxError is raised if the given _string_ is invalid syntax.
-  #
   #    RubyVM::AbstractSyntaxTree.parse("x = 1 + 2")
   #    # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-1:9>
-  def self.parse string, keep_script_lines: false
-    Primitive.ast_s_parse string, keep_script_lines
+  #
+  #  If <tt>keep_script_lines: true</tt> option is provided, the text of the parsed
+  #  source is associated with nodes and is available via Node#script_lines.
+  #
+  #  If <tt>keep_tokens: true</tt> option is provided, Node#tokens are populated.
+  #
+  #  SyntaxError is raised if the given _string_ is invalid syntax. To overwrite this
+  #  behavior, <tt>error_tolerant: true</tt> can be provided. In this case, the parser
+  #  will produce a tree where expressions with syntax errors would be represented by
+  #  Node with <tt>type=:ERROR</tt>.
+  #
+  #     root = RubyVM::AbstractSyntaxTree.parse("x = 1; p(x; y=2")
+  #     # <internal:ast>:33:in `parse': syntax error, unexpected ';', expecting ')' (SyntaxError)
+  #     # x = 1; p(x; y=2
+  #     #           ^
+  #
+  #     root = RubyVM::AbstractSyntaxTree.parse("x = 1; p(x; y=2", error_tolerant: true)
+  #     # (SCOPE@1:0-1:15
+  #     #  tbl: [:x, :y]
+  #     #  args: nil
+  #     #  body: (BLOCK@1:0-1:15 (LASGN@1:0-1:5 :x (LIT@1:4-1:5 1)) (ERROR@1:7-1:11) (LASGN@1:12-1:15 :y (LIT@1:14-1:15 2))))
+  #     root.children.last.children
+  #     # [(LASGN@1:0-1:5 :x (LIT@1:4-1:5 1)),
+  #     #  (ERROR@1:7-1:11),
+  #     #  (LASGN@1:12-1:15 :y (LIT@1:14-1:15 2))]
+  #
+  #  Note that parsing continues even after the errored expression.
+  #
+  def self.parse string, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false
+    Primitive.ast_s_parse string, keep_script_lines, error_tolerant, keep_tokens
   end
 
   #  call-seq:
-  #     RubyVM::AbstractSyntaxTree.parse_file(pathname) -> RubyVM::AbstractSyntaxTree::Node
+  #     RubyVM::AbstractSyntaxTree.parse_file(pathname, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false) -> RubyVM::AbstractSyntaxTree::Node
   #
   #   Reads the file from _pathname_, then parses it like ::parse,
   #   returning the root node of the abstract syntax tree.
@@ -44,13 +69,15 @@ module RubyVM::AbstractSyntaxTree
   #
   #     RubyVM::AbstractSyntaxTree.parse_file("my-app/app.rb")
   #     # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-31:3>
-  def self.parse_file pathname, keep_script_lines: false
-    Primitive.ast_s_parse_file pathname, keep_script_lines
+  #
+  #   See ::parse for explanation of keyword argument meaning and usage.
+  def self.parse_file pathname, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false
+    Primitive.ast_s_parse_file pathname, keep_script_lines, error_tolerant, keep_tokens
   end
 
   #  call-seq:
-  #     RubyVM::AbstractSyntaxTree.of(proc)   -> RubyVM::AbstractSyntaxTree::Node
-  #     RubyVM::AbstractSyntaxTree.of(method) -> RubyVM::AbstractSyntaxTree::Node
+  #     RubyVM::AbstractSyntaxTree.of(proc, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false)   -> RubyVM::AbstractSyntaxTree::Node
+  #     RubyVM::AbstractSyntaxTree.of(method, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false) -> RubyVM::AbstractSyntaxTree::Node
   #
   #   Returns AST nodes of the given _proc_ or _method_.
   #
@@ -63,8 +90,25 @@ module RubyVM::AbstractSyntaxTree
   #
   #     RubyVM::AbstractSyntaxTree.of(method(:hello))
   #     # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-3:3>
-  def self.of body, keep_script_lines: false
-    Primitive.ast_s_of body, keep_script_lines
+  #
+  #   See ::parse for explanation of keyword argument meaning and usage.
+  def self.of body, keep_script_lines: RubyVM.keep_script_lines, error_tolerant: false, keep_tokens: false
+    Primitive.ast_s_of body, keep_script_lines, error_tolerant, keep_tokens
+  end
+
+  #  call-seq:
+  #     RubyVM::AbstractSyntaxTree.node_id_for_backtrace_location(backtrace_location)   -> integer
+  #
+  #   Returns the node id for the given backtrace location.
+  #
+  #     begin
+  #       raise
+  #     rescue =>  e
+  #       loc = e.backtrace_locations.first
+  #       RubyVM::AbstractSyntaxTree.node_id_for_backtrace_location(loc)
+  #     end # => 0
+  def self.node_id_for_backtrace_location backtrace_location
+    Primitive.node_id_for_backtrace_location backtrace_location
   end
 
   # RubyVM::AbstractSyntaxTree::Node instances are created by parse methods in
@@ -122,6 +166,47 @@ module RubyVM::AbstractSyntaxTree
     end
 
     #  call-seq:
+    #     node.tokens -> array
+    #
+    #  Returns tokens corresponding to the location of the node.
+    #  Returns +nil+ if +keep_tokens+ is not enabled when #parse method is called.
+    #
+    #    root = RubyVM::AbstractSyntaxTree.parse("x = 1 + 2", keep_tokens: true)
+    #    root.tokens # => [[0, :tIDENTIFIER, "x", [1, 0, 1, 1]], [1, :tSP, " ", [1, 1, 1, 2]], ...]
+    #    root.tokens.map{_1[2]}.join # => "x = 1 + 2"
+    #
+    #  Token is an array of:
+    #
+    #  - id
+    #  - token type
+    #  - source code text
+    #  - location [ first_lineno, first_column, last_lineno, last_column ]
+    def tokens
+      return nil unless all_tokens
+
+      all_tokens.each_with_object([]) do |token, a|
+        loc = token.last
+        if ([first_lineno, first_column] <=> [loc[0], loc[1]]) <= 0 &&
+           ([last_lineno, last_column]   <=> [loc[2], loc[3]]) >= 0
+           a << token
+        end
+      end
+    end
+
+    #  call-seq:
+    #     node.all_tokens -> array
+    #
+    #  Returns all tokens for the input script regardless the receiver node.
+    #  Returns +nil+ if +keep_tokens+ is not enabled when #parse method is called.
+    #
+    #    root = RubyVM::AbstractSyntaxTree.parse("x = 1 + 2", keep_tokens: true)
+    #    root.all_tokens # => [[0, :tIDENTIFIER, "x", [1, 0, 1, 1]], [1, :tSP, " ", [1, 1, 1, 2]], ...]
+    #    root.children[-1].all_tokens # => [[0, :tIDENTIFIER, "x", [1, 0, 1, 1]], [1, :tSP, " ", [1, 1, 1, 2]], ...]
+    def all_tokens
+      Primitive.ast_node_all_tokens
+    end
+
+    #  call-seq:
     #     node.children -> array
     #
     #  Returns AST nodes under this one.  Each kind of node
@@ -179,12 +264,69 @@ module RubyVM::AbstractSyntaxTree
       lines = script_lines
       if lines
         lines = lines[first_lineno - 1 .. last_lineno - 1]
-        lines[-1] = lines[-1][0...last_column]
-        lines[0] = lines[0][first_column..-1]
+        lines[-1] = lines[-1].byteslice(0...last_column)
+        lines[0] = lines[0].byteslice(first_column..-1)
         lines.join
       else
         nil
       end
     end
+
+    #  call-seq:
+    #     node.locations -> array
+    #
+    #  Returns location objects associated with the AST node.
+    #  The returned array contains RubyVM::AbstractSyntaxTree::Location.
+    def locations
+      Primitive.ast_node_locations
+    end
+  end
+
+  # RubyVM::AbstractSyntaxTree::Location instances are created by
+  # RubyVM::AbstractSyntaxTree::Node#locations.
+  #
+  # This class is MRI specific.
+  #
+  class Location
+
+    #  call-seq:
+    #     location.first_lineno -> integer
+    #
+    #  The line number in the source code where this AST's text began.
+    def first_lineno
+      Primitive.ast_location_first_lineno
+    end
+
+    #  call-seq:
+    #     location.first_column -> integer
+    #
+    #  The column number in the source code where this AST's text began.
+    def first_column
+      Primitive.ast_location_first_column
+    end
+
+    #  call-seq:
+    #     location.last_lineno -> integer
+    #
+    #  The line number in the source code where this AST's text ended.
+    def last_lineno
+      Primitive.ast_location_last_lineno
+    end
+
+    #  call-seq:
+    #     location.last_column -> integer
+    #
+    #  The column number in the source code where this AST's text ended.
+    def last_column
+      Primitive.ast_location_last_column
+    end
+
+    #  call-seq:
+    #     location.inspect -> string
+    #
+    #  Returns debugging information about this location as a string.
+    def inspect
+      Primitive.ast_location_inspect
+    end
   end
 end
diff --git a/autogen.sh b/autogen.sh
index f8cdf3c0c1..6cbc5dddab 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -1,17 +1,22 @@
 #!/bin/sh
 
+# Clear PWD to force commands to recompute working directory
 PWD=
+
+# Figure out the source directory for this script
+# configure.ac should be in the same place
 case "$0" in
-*/*) srcdir=`dirname $0`;;
-*) srcdir="";;
+    */* )  srcdir=`dirname "$0"` ;; # Called with path
+    *   )  srcdir="";; # Otherwise
 esac
 
-symlink='--install --symlink'
+# If install-only is explicitly requested, disable symlink flags
 case " $* " in
-    *" -i "*|*" --install "*)
-        # reset to copy missing standard auxiliary files, instead of symlinks
-        symlink=
-        ;;
+    *" -i "* | *" --install"* ) symlink_flags="" ;;
+    *                         ) symlink_flags="--install --symlink" ;;
 esac
 
-exec ${AUTORECONF:-autoreconf} ${symlink} "$@" ${srcdir:+"$srcdir"}
+exec ${AUTORECONF:-autoreconf} \
+     $symlink_flags \
+     "$@" \
+     $srcdir
diff --git a/basictest/test.rb b/basictest/test.rb
index 95875b52a6..711e4f4ab3 100755
--- a/basictest/test.rb
+++ b/basictest/test.rb
@@ -879,7 +879,7 @@ $x.sort!{|a,b| b-a}		# reverse sort
 test_ok($x == [7,5,3,2,1])
 
 # split test
-$x = "The Book of Mormon"
+$x = +"The Book of Mormon"
 test_ok($x.split(//).reverse!.join == $x.reverse)
 test_ok($x.reverse == $x.reverse!)
 test_ok("1 byte string".split(//).reverse.join(":") == "g:n:i:r:t:s: :e:t:y:b: :1")
@@ -1643,7 +1643,7 @@ test_ok(/^(?:ab+)+/ =~ "ababb" && $& == "ababb")
 test_ok(/(\s+\d+){2}/ =~ " 1 2" && $& == " 1 2")
 test_ok(/(?:\s+\d+){2}/ =~ " 1 2" && $& == " 1 2")
 
-$x = <<END;
+$x = +<<END;
 ABCD
 ABCD
 END
@@ -1682,12 +1682,12 @@ test_ok(?a == ?a)
 test_ok(?\C-a == "\1")
 test_ok(?\M-a == "\341")
 test_ok(?\M-\C-a == "\201")
-test_ok("a".upcase![0] == ?A)
-test_ok("A".downcase![0] == ?a)
-test_ok("abc".tr!("a-z", "A-Z") == "ABC")
-test_ok("aabbcccc".tr_s!("a-z", "A-Z") == "ABC")
-test_ok("abcc".squeeze!("a-z") == "abc")
-test_ok("abcd".delete!("bc") == "ad")
+test_ok("a".dup.upcase![0] == ?A)
+test_ok("A".dup.downcase![0] == ?a)
+test_ok("abc".dup.tr!("a-z", "A-Z") == "ABC")
+test_ok("aabbcccc".dup.tr_s!("a-z", "A-Z") == "ABC")
+test_ok("abcc".dup.squeeze!("a-z") == "abc")
+test_ok("abcd".dup.delete!("bc") == "ad")
 
 $x = "abcdef"
 $y = [ ?a, ?b, ?c, ?d, ?e, ?f ]
@@ -1700,7 +1700,7 @@ $x.each_byte {|i|
 }
 test_ok(!$bad)
 
-s = "a string"
+s = +"a string"
 s[0..s.size]="another string"
 test_ok(s == "another string")
 
diff --git a/benchmark/README.md b/benchmark/README.md
index e11381cad9..9f9192685e 100644
--- a/benchmark/README.md
+++ b/benchmark/README.md
@@ -27,6 +27,7 @@ benchmark-driver benchmark/*.yml
 See also:
 
 ```console
+benchmark-driver --help
 Usage: benchmark-driver [options] RUBY|YAML...
     -r, --runner TYPE                Specify runner type: ips, time, memory, once, block (default: ips)
     -o, --output TYPE                Specify output type: compare, simple, markdown, record, all (default: compare)
@@ -39,7 +40,7 @@ Usage: benchmark-driver [options] RUBY|YAML...
         --filter REGEXP              Filter out benchmarks with given regexp
         --run-duration SECONDS       Warmup estimates loop_count to run for this duration (default: 3)
         --timeout SECONDS            Timeout ruby command execution with timeout(1)
-    -v, --verbose                    Verbose mode. Multiple -v options increase visilibity (max: 2)
+    -v, --verbose                    Verbose mode. Multiple -v options increase visibility (max: 2)
 ```
 
 ## make benchmark
diff --git a/benchmark/app_aobench.rb b/benchmark/app_aobench.rb
index 16296af12b..c1546e08ab 100644
--- a/benchmark/app_aobench.rb
+++ b/benchmark/app_aobench.rb
@@ -151,7 +151,7 @@ def clamp(f)
   i.to_i
 end
 
-def otherBasis(basis, n)
+def orthoBasis(basis, n)
   basis[2] = Vec.new(n.x, n.y, n.z)
   basis[1] = Vec.new(0.0, 0.0, 0.0)
 
@@ -183,7 +183,7 @@ class Scene
 
   def ambient_occlusion(isect)
     basis = Array.new
-    otherBasis(basis, isect.n)
+    orthoBasis(basis, isect.n)
 
     ntheta    = NAO_SAMPLES
     nphi      = NAO_SAMPLES
diff --git a/benchmark/app_fib.rb b/benchmark/app_fib.rb
index 34a7b2e725..e61bc8aa32 100644
--- a/benchmark/app_fib.rb
+++ b/benchmark/app_fib.rb
@@ -1,4 +1,4 @@
-def fib n
+def fib(n)
   if n < 3
     1
   else
diff --git a/benchmark/array_large_literal.yml b/benchmark/array_large_literal.yml
new file mode 100644
index 0000000000..423d68391f
--- /dev/null
+++ b/benchmark/array_large_literal.yml
@@ -0,0 +1,19 @@
+prelude: |
+  def def_array(size)
+    Object.class_eval(<<-END)
+      def array_#{size}
+        x = 1
+        [#{(['x'] * size).join(',')}]
+      end
+    END
+  end
+  def_array(100)
+  def_array(1000)
+  def_array(10000)
+  def_array(100000)
+benchmark:
+  array_100: array_100
+  array_1000: array_1000
+  array_10000: array_10000
+  array_100000: array_100000
+
diff --git a/benchmark/array_sort_int.yml b/benchmark/array_sort_int.yml
new file mode 100644
index 0000000000..7b9027ebf7
--- /dev/null
+++ b/benchmark/array_sort_int.yml
@@ -0,0 +1,15 @@
+prelude: |
+  ary2 = 2.times.to_a.shuffle
+  ary10 = 10.times.to_a.shuffle
+  ary100 = 100.times.to_a.shuffle
+  ary1000 = 1000.times.to_a.shuffle
+  ary10000 = 10000.times.to_a.shuffle
+
+benchmark:
+  ary2.sort: ary2.sort
+  ary10.sort: ary10.sort
+  ary100.sort: ary100.sort
+  ary1000.sort: ary1000.sort
+  ary10000.sort: ary10000.sort
+
+loop_count: 10000
diff --git a/benchmark/buffer_each.yml b/benchmark/buffer_each.yml
new file mode 100644
index 0000000000..417941104e
--- /dev/null
+++ b/benchmark/buffer_each.yml
@@ -0,0 +1,27 @@
+prelude: |
+  # frozen_string_literal: true
+  Warning[:experimental] = false
+  string = "The quick brown fox jumped over the lazy dog."
+  array = string.bytes
+  buffer = IO::Buffer.for(string)
+benchmark:
+  string.each_byte: |
+    upcased = String.new
+    string.each_byte do |byte|
+      upcased << (byte ^ 32)
+    end
+  array.each: |
+    upcased = String.new
+    array.each do |byte|
+      upcased << (byte ^ 32)
+    end
+  buffer.each: |
+    upcased = String.new
+    buffer.each(:U8) do |offset, byte|
+      upcased << (byte ^ 32)
+    end
+  buffer.each_byte: |
+    upcased = String.new
+    buffer.each_byte do |byte|
+      upcased << (byte ^ 32)
+    end
diff --git a/benchmark/buffer_get.yml b/benchmark/buffer_get.yml
index bb9ca7e94a..9e1f99d64e 100644
--- a/benchmark/buffer_get.yml
+++ b/benchmark/buffer_get.yml
@@ -1,10 +1,25 @@
 prelude: |
   # frozen_string_literal: true
   Warning[:experimental] = false
-  buffer = IO::Buffer.new(32, IO::Buffer::MAPPED)
-  string = "\0" * 32
+  string = "The quick brown fox jumped over the lazy dog."
+  buffer = IO::Buffer.for(string)
+  format = [:U32, :U32, :U32, :U32]
 benchmark:
-  buffer.get_value: |
-    buffer.get_value(:U32, 0)
   string.unpack1: |
-    string.unpack1("N")
+    [
+      string.unpack1("N"),
+      string.unpack1("N", offset: 4),
+      string.unpack1("N", offset: 8),
+      string.unpack1("N", offset: 12),
+    ]
+  buffer.get_value: |
+    [
+      buffer.get_value(:U32, 0),
+      buffer.get_value(:U32, 4),
+      buffer.get_value(:U32, 8),
+      buffer.get_value(:U32, 12),
+    ]
+  buffer.get_values: |
+    buffer.get_values(format, 0)
+  string.unpack: |
+    string.unpack("NNNN")
diff --git a/benchmark/cgi_escape_html.yml b/benchmark/cgi_escape_html.yml
index af6abd08ac..655be9d7d8 100644
--- a/benchmark/cgi_escape_html.yml
+++ b/benchmark/cgi_escape_html.yml
@@ -1,32 +1,23 @@
-prelude: require 'cgi/escape'
+prelude: |
+  # frozen_string_literal: true
+  require 'cgi/escape'
 benchmark:
-  - name: escape_html_blank
-    prelude: str = ""
-    script: CGI.escapeHTML(str)
+  - script: CGI.escapeHTML("")
     loop_count: 20000000
-  - name: escape_html_short_none
-    prelude: str = "abcde"
-    script: CGI.escapeHTML(str)
+  - script: CGI.escapeHTML("abcde")
     loop_count: 20000000
-  - name: escape_html_short_one
-    prelude: str = "abcd<"
-    script: CGI.escapeHTML(str)
+  - script: CGI.escapeHTML("abcd<")
     loop_count: 20000000
-  - name: escape_html_short_all
-    prelude: str = "'&\"<>"
-    script: CGI.escapeHTML(str)
+  - script: CGI.escapeHTML("'&\"<>")
     loop_count: 5000000
-  - name: escape_html_long_none
-    prelude: str = "abcde" * 300
-    script: CGI.escapeHTML(str)
+  - prelude: long_no_escape = "abcde" * 300
+    script: CGI.escapeHTML(long_no_escape)
     loop_count: 1000000
-  - name: escape_html_long_all
-    prelude: str = "'&\"<>" * 10
-    script: CGI.escapeHTML(str)
+  - prelude: long_all_escape = "'&\"<>" * 10
+    script: CGI.escapeHTML(long_all_escape)
     loop_count: 1000000
-  - name: escape_html_real
-    prelude: | # http://example.com/
-      str = <<~HTML
+  - prelude: | # http://example.com/
+      example_html = <<~HTML
         <body>
         <div>
             <h1>Example Domain</h1>
@@ -36,5 +27,5 @@ benchmark:
         </div>
         </body>
       HTML
-    script: CGI.escapeHTML(str)
+    script: CGI.escapeHTML(example_html)
     loop_count: 1000000
diff --git a/benchmark/class_superclass.yml b/benchmark/class_superclass.yml
new file mode 100644
index 0000000000..847ff811f1
--- /dev/null
+++ b/benchmark/class_superclass.yml
@@ -0,0 +1,23 @@
+prelude: |
+  class SimpleClass; end
+  class OneModuleClass
+    1.times { include Module.new }
+  end
+  class MediumClass
+    10.times { include Module.new }
+  end
+  class LargeClass
+    100.times { include Module.new }
+  end
+benchmark:
+  object_class_superclass: |
+    Object.superclass
+  simple_class_superclass: |
+    SimpleClass.superclass
+  one_module_class: |
+    OneModuleClass.superclass
+  medium_class_superclass: |
+    MediumClass.superclass
+  large_class_superclass: |
+    LargeClass.superclass
+loop_count: 20000000
diff --git a/benchmark/enum_minmax.yml b/benchmark/enum_minmax.yml
new file mode 100644
index 0000000000..9d01731abb
--- /dev/null
+++ b/benchmark/enum_minmax.yml
@@ -0,0 +1,25 @@
+prelude: |
+  set2 = 2.times.to_a.shuffle.to_set
+  set10 = 10.times.to_a.shuffle.to_set
+  set100 = 100.times.to_a.shuffle.to_set
+  set1000 = 1000.times.to_a.shuffle.to_set
+  set10000 = 10000.times.to_a.shuffle.to_set
+
+benchmark:
+  set2.min: set2.min
+  set10.min: set10.min
+  set100.min: set100.min
+  set1000.min: set1000.min
+  set10000.min: set10000.min
+  set2.max: set2.max
+  set10.max: set10.max
+  set100.max: set100.max
+  set1000.max: set1000.max
+  set10000.max: set10000.max
+  set2.minmax: set2.minmax
+  set10.minmax: set10.minmax
+  set100.minmax: set100.minmax
+  set1000.minmax: set1000.minmax
+  set10000.minmax: set10000.minmax
+
+loop_count: 10000
diff --git a/benchmark/enum_sort.yml b/benchmark/enum_sort.yml
new file mode 100644
index 0000000000..6f26e748c6
--- /dev/null
+++ b/benchmark/enum_sort.yml
@@ -0,0 +1,15 @@
+prelude: |
+  set2 = 2.times.to_a.shuffle.to_set
+  set10 = 10.times.to_a.shuffle.to_set
+  set100 = 100.times.to_a.shuffle.to_set
+  set1000 = 1000.times.to_a.shuffle.to_set
+  set10000 = 10000.times.to_a.shuffle.to_set
+
+benchmark:
+  set2.sort_by: set2.sort_by { 0 }
+  set10.sort_by: set10.sort_by { 0 }
+  set100.sort_by: set100.sort_by { 0 }
+  set1000.sort_by: set1000.sort_by { 0 }
+  set10000.sort_by: set10000.sort_by { 0 }
+
+loop_count: 10000
diff --git a/benchmark/enum_sort_by.yml b/benchmark/enum_sort_by.yml
new file mode 100644
index 0000000000..d386353888
--- /dev/null
+++ b/benchmark/enum_sort_by.yml
@@ -0,0 +1,53 @@
+prelude: |
+  array_length = 2
+  fixnum_array2 = array_length.times.to_a.map {rand(10000)}
+  float_array2 = array_length.times.to_a.map {rand(10000.0).to_f}
+  string_array2 = array_length.times.to_a.map {"r" * rand(1..10000)}
+  mix_array2 = array_length.times.to_a.map {if rand(1..100) <= 50 then rand(1..10000).to_f else rand(1..10000) end}
+  all_zero_array2 =array_length.times.to_a.map {0}
+
+  array_length = 10
+  fixnum_array10 = array_length.times.to_a.map {rand(10000)}
+  float_array10 = array_length.times.to_a.map {rand(10000.0).to_f}
+  string_array10 = array_length.times.to_a.map {"r" * rand(1..10000)}
+  mix_array10 = array_length.times.to_a.map {if rand(1..100) <= 50 then rand(1..10000).to_f else rand(1..10000) end}
+  all_zero_array10 =array_length.times.to_a.map {0}
+
+  array_length = 1000
+  fixnum_array1000 = array_length.times.to_a.map {rand(10000)}
+  float_array1000 = array_length.times.to_a.map {rand(10000.0).to_f}
+  string_array1000 = array_length.times.to_a.map {"r" * rand(1..10000)}
+  mix_array1000 = array_length.times.to_a.map {if rand(1..100) <= 50 then rand(1..10000).to_f else rand(1..10000) end}
+  all_zero_array1000 =array_length.times.to_a.map {0}
+
+  array_length = 100000
+  fixnum_array100000 = array_length.times.to_a.map {rand(10000)}
+  float_array100000 = array_length.times.to_a.map {rand(10000.0).to_f}
+  string_array100000 = array_length.times.to_a.map {"r" * rand(1..10000)}
+  mix_array100000 = array_length.times.to_a.map {if rand(1..100) <= 50 then rand(1..10000).to_f else rand(1..10000) end}
+  all_zero_array100000 =array_length.times.to_a.map {0}
+
+benchmark:
+  fixnum_array2.sort_by: fixnum_array2.sort_by {|a| a}
+  float_array2.sort_by:  float_array2.sort_by {|a| a}
+  string_length2.sort_by: string_array2.sort_by {|a| a.length}
+  mix_array2.sort_by:  mix_array2.sort_by {|a| a}
+  all_zero2.sort_by: all_zero_array2.sort_by{|a| a}
+
+  fixnum_array10.sort_by: fixnum_array10.sort_by {|a| a}
+  float_array10.sort_by:  float_array10.sort_by {|a| a}
+  string_length10.sort_by: string_array10.sort_by {|a| a.length}
+  mix_array10.sort_by:  mix_array10.sort_by {|a| a}
+  all_zero10.sort_by: all_zero_array10.sort_by{|a| a}
+
+  fixnum_array1000.sort_by: fixnum_array1000.sort_by {|a| a}
+  float_array1000.sort_by:  float_array1000.sort_by {|a| a}
+  string_length1000.sort_by: string_array1000.sort_by {|a| a.length}
+  mix_array1000.sort_by:  mix_array1000.sort_by {|a| a}
+  all_zero1000.sort_by: all_zero_array1000.sort_by{|a| a}
+
+  fixnum_array100000.sort_by: fixnum_array100000.sort_by {|a| a}
+  float_array100000.sort_by:  float_array100000.sort_by {|a| a}
+  string_length100000.sort_by: string_array100000.sort_by {|a| a.length}
+  mix_array100000.sort_by:  mix_array100000.sort_by {|a| a}
+  all_zero100000.sort_by: all_zero_array100000.sort_by{|a| a}
diff --git a/benchmark/erb_escape_html.yml b/benchmark/erb_escape_html.yml
new file mode 100644
index 0000000000..ca28d756e7
--- /dev/null
+++ b/benchmark/erb_escape_html.yml
@@ -0,0 +1,31 @@
+prelude: |
+  # frozen_string_literal: true
+  require 'erb'
+benchmark:
+  - script: ERB::Util.html_escape("")
+    loop_count: 20000000
+  - script: ERB::Util.html_escape("abcde")
+    loop_count: 20000000
+  - script: ERB::Util.html_escape("abcd<")
+    loop_count: 20000000
+  - script: ERB::Util.html_escape("'&\"<>")
+    loop_count: 5000000
+  - prelude: long_no_escape = "abcde" * 300
+    script: ERB::Util.html_escape(long_no_escape)
+    loop_count: 1000000
+  - prelude: long_all_escape = "'&\"<>" * 10
+    script: ERB::Util.html_escape(long_all_escape)
+    loop_count: 1000000
+  - prelude: | # http://example.com/
+      example_html = <<~HTML
+        <body>
+        <div>
+            <h1>Example Domain</h1>
+            <p>This domain is established to be used for illustrative examples in documents. You may use this
+            domain in examples without prior coordination or asking for permission.</p>
+            <p><a href="http://www.iana.org/domains/example">More information...</a></p>
+        </div>
+        </body>
+      HTML
+    script: ERB::Util.html_escape(example_html)
+    loop_count: 1000000
diff --git a/benchmark/file_dirname.yml b/benchmark/file_dirname.yml
new file mode 100644
index 0000000000..43a81c9371
--- /dev/null
+++ b/benchmark/file_dirname.yml
@@ -0,0 +1,6 @@
+prelude: |
+  # frozen_string_literal: true
+benchmark:
+  long: File.dirname("/Users/george/src/github.com/ruby/ruby/benchmark/file_dirname.yml")
+  short: File.dirname("foo/bar")
+  n_4: File.dirname("/Users/george/src/github.com/ruby/ruby/benchmark/file_dirname.yml", 4)
diff --git a/benchmark/file_extname.yml b/benchmark/file_extname.yml
new file mode 100644
index 0000000000..fb16e55840
--- /dev/null
+++ b/benchmark/file_extname.yml
@@ -0,0 +1,6 @@
+prelude: |
+  # frozen_string_literal: true
+benchmark:
+  long: File.extname("/Users/george/src/github.com/ruby/ruby/benchmark/file_dirname.yml")
+  long_name: File.extname("Users_george_src_github.com_ruby_ruby_benchmark_file_dirname.yml")
+  short: File.extname("foo/bar")
diff --git a/benchmark/file_join.yml b/benchmark/file_join.yml
new file mode 100644
index 0000000000..845257cf1e
--- /dev/null
+++ b/benchmark/file_join.yml
@@ -0,0 +1,7 @@
+prelude: |
+  # frozen_string_literal: true
+benchmark:
+  two_strings: File.join(__FILE__, "path")
+  many_strings: File.join(__FILE__, "path", "a", "b", "c", "d")
+  array: File.join([__FILE__, "path", "a", "b", "c", "d"])
+  mixed: File.join(__FILE__, "path", "a", "b", ["c", "d"])
diff --git a/benchmark/hash_aref_str_lit.yml b/benchmark/hash_aref_str_lit.yml
new file mode 100644
index 0000000000..ed8142bcf1
--- /dev/null
+++ b/benchmark/hash_aref_str_lit.yml
@@ -0,0 +1,20 @@
+prelude: |
+  # frozen_string_literal: true
+  hash = 10.times.to_h do |i|
+    [i, i]
+  end
+  dyn_sym = "dynamic_symbol".to_sym
+  binary = RubyVM::InstructionSequence.compile("# frozen_string_literal: true\n'iseq_load'").to_binary
+  iseq_literal_string = RubyVM::InstructionSequence.load_from_binary(binary).eval
+
+  hash[:some_symbol] = 1
+  hash[dyn_sym] = 2
+  hash["small"] = 3
+  hash["frozen_string_literal"] = 4
+  hash[iseq_literal_string] = 5
+benchmark:
+  symbol: hash[:some_symbol]
+  dyn_symbol: hash[dyn_sym]
+  small_lit: hash["small"]
+  frozen_lit: hash["frozen_string_literal"]
+  iseq_lit: hash[iseq_literal_string]
diff --git a/benchmark/hash_key.yml b/benchmark/hash_key.yml
new file mode 100644
index 0000000000..cab4cf9ca4
--- /dev/null
+++ b/benchmark/hash_key.yml
@@ -0,0 +1,5 @@
+prelude: |
+  obj = Object.new
+  hash = { obj => true }
+benchmark: hash.key?(obj)
+loop_count: 30000000
diff --git a/benchmark/hash_new.yml b/benchmark/hash_new.yml
new file mode 100644
index 0000000000..9d8e34187f
--- /dev/null
+++ b/benchmark/hash_new.yml
@@ -0,0 +1,16 @@
+prelude: |
+  has_hash_with_capa = Hash.instance_method(:initialize).parameters.include?([:key, :capacity])
+  strings_1k = 1_000.times.map { |i| -i.to_s.freeze }
+  strings_100k = 100_000.times.map { |i| -i.to_s.freeze }
+benchmark:
+  new: Hash.new
+  new_with_capa_1k: |
+    h = has_hash_with_capa ? Hash.new(capacity: strings_1k.size) : {}
+    strings_1k.each do |x|
+      h[x] = true
+    end
+  new_with_capa_100k: |
+    h = has_hash_with_capa ? Hash.new(capacity: strings_100k.size) : {}
+    strings_100k.each do |x|
+      h[x] = true
+    end
diff --git a/benchmark/io_close.yml b/benchmark/io_close.yml
new file mode 100644
index 0000000000..a552872884
--- /dev/null
+++ b/benchmark/io_close.yml
@@ -0,0 +1,13 @@
+prelude: |
+  ios = 1000.times.map do
+    100.times.map{IO.pipe}
+  end
+benchmark:
+  # Close IO
+  io_close: |
+    # Process each batch of ios per iteration of the benchmark.
+    ios.pop.each do |r, w|
+      r.close
+      w.close
+    end
+loop_count: 100
diff --git a/benchmark/io_close_contended.yml b/benchmark/io_close_contended.yml
new file mode 100644
index 0000000000..1d9e4e0d0f
--- /dev/null
+++ b/benchmark/io_close_contended.yml
@@ -0,0 +1,21 @@
+prelude: |
+  ios = 100.times.map do
+    10.times.map do
+      pipe = IO.pipe.tap do |r, w|
+        Thread.new do
+          r.read
+        rescue IOError
+          # Ignore
+        end
+      end
+    end
+  end
+benchmark:
+  # Close IO
+  io_close_contended: |
+    # Process each batch of ios per iteration of the benchmark.
+    ios.pop.each do |r, w|
+      r.close
+      w.close
+    end
+loop_count: 10
diff --git a/benchmark/lib/benchmark_driver/runner/mjit.rb b/benchmark/lib/benchmark_driver/runner/mjit.rb
deleted file mode 100644
index 1d4693e8be..0000000000
--- a/benchmark/lib/benchmark_driver/runner/mjit.rb
+++ /dev/null
@@ -1,34 +0,0 @@
-require 'benchmark_driver/struct'
-require 'benchmark_driver/metric'
-require 'erb'
-
-# A runner to measure after-JIT performance easily
-class BenchmarkDriver::Runner::Mjit < BenchmarkDriver::Runner::Ips
-  # JobParser returns this, `BenchmarkDriver::Runner.runner_for` searches "*::Job"
-  Job = Class.new(BenchmarkDriver::DefaultJob)
-
-  # Dynamically fetched and used by `BenchmarkDriver::JobParser.parse`
-  JobParser = BenchmarkDriver::DefaultJobParser.for(klass: Job, metrics: [METRIC]).extend(Module.new{
-    def parse(**)
-      jobs = super
-      jobs.map do |job|
-        job = job.dup
-        job.prelude = "#{job.prelude}\n#{<<~EOS}"
-          if defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled?
-            __bmdv_ruby_i = 0
-            while __bmdv_ruby_i < 10000 # jit_min_calls
-              #{job.script}
-              __bmdv_ruby_i += 1
-            end
-            RubyVM::MJIT.pause # compile
-            #{job.script}
-            RubyVM::MJIT.resume; RubyVM::MJIT.pause # recompile
-            #{job.script}
-            RubyVM::MJIT.resume; RubyVM::MJIT.pause # recompile 2
-          end
-        EOS
-        job
-      end
-    end
-  })
-end
diff --git a/benchmark/lib/benchmark_driver/runner/ractor.rb b/benchmark/lib/benchmark_driver/runner/ractor.rb
index c730b8e4a5..fd9c2dd4db 100644
--- a/benchmark/lib/benchmark_driver/runner/ractor.rb
+++ b/benchmark/lib/benchmark_driver/runner/ractor.rb
@@ -87,7 +87,7 @@ __bmdv_ractors << Ractor.new(__bmdv_loop_after - __bmdv_loop_before) { |__bmdv_l
 <% end %>
 
 # Wait for all Ractors before executing code to write results
-__bmdv_ractors.map!(&:take)
+__bmdv_ractors.map!(&:value)
 
 <% results.each do |result| %>
 File.write(<%= result.dump %>, __bmdv_ractors.shift)
diff --git a/benchmark/loop_each.yml b/benchmark/loop_each.yml
new file mode 100644
index 0000000000..1c757185a8
--- /dev/null
+++ b/benchmark/loop_each.yml
@@ -0,0 +1,4 @@
+prelude: |
+  arr = [nil] * 30_000_000
+benchmark:
+  loop_each: arr.each{|e|}
diff --git a/benchmark/loop_generator.rb b/benchmark/loop_generator.rb
index d3375c744c..6a3194b670 100644
--- a/benchmark/loop_generator.rb
+++ b/benchmark/loop_generator.rb
@@ -1,4 +1,4 @@
-max = 600000
+max = 6000000
 
 if defined? Fiber
   gen = (1..max).each
diff --git a/benchmark/loop_times_megamorphic.yml b/benchmark/loop_times_megamorphic.yml
new file mode 100644
index 0000000000..f9343ba897
--- /dev/null
+++ b/benchmark/loop_times_megamorphic.yml
@@ -0,0 +1,7 @@
+prelude: |
+  eval(<<~EOS)
+    def loop_times_megamorphic
+      #{"1.times {|i|};" * 1000}
+    end
+  EOS
+benchmark: loop_times_megamorphic
diff --git a/benchmark/mjit_exivar.yml b/benchmark/mjit_exivar.yml
deleted file mode 100644
index 2584fa6410..0000000000
--- a/benchmark/mjit_exivar.yml
+++ /dev/null
@@ -1,18 +0,0 @@
-type: lib/benchmark_driver/runner/mjit
-prelude: |
-  class Bench < Hash
-    def initialize
-      @exivar = nil
-    end
-
-    def exivar
-      @exivar
-    end
-  end
-
-  bench = Bench.new
-
-benchmark:
-  mjit_exivar: bench.exivar
-
-loop_count: 200000000
diff --git a/benchmark/mjit_integer.yml b/benchmark/mjit_integer.yml
deleted file mode 100644
index a6b5c9ee16..0000000000
--- a/benchmark/mjit_integer.yml
+++ /dev/null
@@ -1,32 +0,0 @@
-type: lib/benchmark_driver/runner/mjit
-prelude: |
-  def mjit_abs(int)        int.abs        end
-  def mjit_bit_length(int) int.bit_length end
-  def mjit_comp(int)       ~int           end
-  def mjit_even?(int)      int.even?      end
-  def mjit_integer?(int)   int.integer?   end
-  def mjit_magnitude(int)  int.magnitude  end
-  def mjit_odd?(int)       int.odd?       end
-  def mjit_ord(int)        int.ord        end
-  def mjit_size(int)       int.size       end
-  def mjit_to_i(int)       int.to_i       end
-  def mjit_to_int(int)     int.to_int     end
-  def mjit_uminus(int)     -int           end
-  def mjit_zero?(int)      int.zero?      end
-
-benchmark:
-  - mjit_abs(-1)
-  - mjit_bit_length(100)
-  - mjit_comp(1)
-  - mjit_even?(2)
-  - mjit_integer?(0)
-  - mjit_magnitude(-1)
-  - mjit_odd?(1)
-  - mjit_ord(1)
-  - mjit_size(1)
-  - mjit_to_i(1)
-  - mjit_to_int(1)
-  - mjit_uminus(1)
-  - mjit_zero?(0)
-
-loop_count: 40000000
diff --git a/benchmark/mjit_kernel.yml b/benchmark/mjit_kernel.yml
deleted file mode 100644
index 7720e65c2c..0000000000
--- a/benchmark/mjit_kernel.yml
+++ /dev/null
@@ -1,20 +0,0 @@
-type: lib/benchmark_driver/runner/mjit
-prelude: |
-  def mjit_class(obj)
-    obj.class
-  end
-
-  def mjit_frozen?(obj)
-    obj.frozen?
-  end
-
-  str = ""
-  fstr = "".freeze
-
-benchmark:
-  - mjit_class(self)
-  - mjit_class(1)
-  - mjit_frozen?(str)
-  - mjit_frozen?(fstr)
-
-loop_count: 40000000
diff --git a/benchmark/mjit_leave.yml b/benchmark/mjit_leave.yml
deleted file mode 100644
index 9ac68b164b..0000000000
--- a/benchmark/mjit_leave.yml
+++ /dev/null
@@ -1,8 +0,0 @@
-type: lib/benchmark_driver/runner/mjit
-prelude: |
-  def leave
-    nil
-  end
-benchmark:
-  mjit_leave: leave
-loop_count: 200000000
diff --git a/benchmark/mjit_opt_cc_insns.yml b/benchmark/mjit_opt_cc_insns.yml
deleted file mode 100644
index fed6d34bd5..0000000000
--- a/benchmark/mjit_opt_cc_insns.yml
+++ /dev/null
@@ -1,27 +0,0 @@
-# opt_* insns using vm_method_cfunc_is with send-compatible operands:
-#   * opt_nil_p
-#   * opt_not
-#   * opt_eq
-type: lib/benchmark_driver/runner/mjit
-prelude: |
-  def mjit_nil?(obj)
-    obj.nil?
-  end
-
-  def mjit_not(obj)
-    !obj
-  end
-
-  def mjit_eq(a, b)
-    a == b
-  end
-
-benchmark:
-  - script: mjit_nil?(1)
-    loop_count: 40000000
-  - script: mjit_not(1)
-    loop_count: 40000000
-  - script: mjit_eq(1, nil)
-    loop_count: 8000000
-  - script: mjit_eq(nil, 1)
-    loop_count: 8000000
diff --git a/benchmark/mjit_struct_aref.yml b/benchmark/mjit_struct_aref.yml
deleted file mode 100644
index bfba1323f2..0000000000
--- a/benchmark/mjit_struct_aref.yml
+++ /dev/null
@@ -1,10 +0,0 @@
-type: lib/benchmark_driver/runner/mjit
-prelude: |
-  def mjit_struct_aref(struct)
-    struct.aa
-  end
-  struct = Struct.new(:a0, :a1, :a2, :a3, :a4, :a5, :a6, :a7, :a8, :a9, :aa).new
-
-benchmark: mjit_struct_aref(struct)
-
-loop_count: 40000000
diff --git a/benchmark/module_eqq.yml b/benchmark/module_eqq.yml
index a561fb86dc..2f9c490d92 100644
--- a/benchmark/module_eqq.yml
+++ b/benchmark/module_eqq.yml
@@ -1,4 +1,5 @@
 prelude: |
+  module SomeModule; end
   class SimpleClass; end
   class MediumClass
     10.times { include Module.new }
@@ -24,4 +25,8 @@ benchmark:
     SimpleClass === LargeObj
   simple_class_eqq_huge_obj: |
     SimpleClass === HugeObj
-loop_count: 20000000
+  simple_class_eqq_module: |
+    SimpleClass === HugeObj
+  module_eqq_module: |
+    SomeModule === HugeObj
+loop_count: 10000000
diff --git a/benchmark/nilclass.yml b/benchmark/nilclass.yml
index fba67a5f6a..66234c4cdf 100644
--- a/benchmark/nilclass.yml
+++ b/benchmark/nilclass.yml
@@ -1,6 +1,16 @@
+prelude: |
+  def a = nil
 benchmark:
+  rationalize:
+    nil.rationalize
+  to_c: |
+    nil.to_c
   to_i: |
     nil.to_i
   to_f: |
     nil.to_f
+  to_r: |
+    nil.to_r
+  splat: |
+    a(*nil)
 loop_count: 100000
diff --git a/benchmark/numeric_methods.yml b/benchmark/numeric_methods.yml
index 433c2268a3..1384902935 100644
--- a/benchmark/numeric_methods.yml
+++ b/benchmark/numeric_methods.yml
@@ -10,4 +10,20 @@ benchmark:
     int.finite?
   infinite?: |
     int.infinite?
+  integer_real: |
+    int.real
+  float_real: |
+    flo.real
+  integr_imag: |
+    int.imag
+  float_imag: |
+    flo.imag
+  integer_conj: |
+    int.conj
+  float_conj: |
+    flo.conj
+  integer_numerator: |
+    int.numerator
+  integer_denominator: |
+    int.denominator
 loop_count: 20000000
diff --git a/benchmark/object_allocate.yml b/benchmark/object_allocate.yml
index 93ff463e41..c6269923f0 100644
--- a/benchmark/object_allocate.yml
+++ b/benchmark/object_allocate.yml
@@ -11,6 +11,26 @@ prelude: |
   class OneTwentyEight
     128.times { include(Module.new) }
   end
+  class OnePositional
+    def initialize a; end
+  end
+  class TwoPositional
+    def initialize a, b; end
+  end
+  class ThreePositional
+    def initialize a, b, c; end
+  end
+  class FourPositional
+    def initialize a, b, c, d; end
+  end
+  class KWArg
+    def initialize a:, b:, c:, d:
+    end
+  end
+  class Mixed
+    def initialize a, b, c:, d:
+    end
+  end
   # Disable GC to see raw throughput:
   GC.disable
 benchmark:
@@ -18,4 +38,12 @@ benchmark:
   allocate_32_deep: ThirtyTwo.new
   allocate_64_deep: SixtyFour.new
   allocate_128_deep: OneTwentyEight.new
+  allocate_1_positional_params: OnePositional.new(1)
+  allocate_2_positional_params: TwoPositional.new(1, 2)
+  allocate_3_positional_params: ThreePositional.new(1, 2, 3)
+  allocate_4_positional_params: FourPositional.new(1, 2, 3, 4)
+  allocate_kwarg_params: "KWArg.new(a: 1, b: 2, c: 3, d: 4)"
+  allocate_mixed_params: "Mixed.new(1, 2, c: 3, d: 4)"
+  allocate_no_params: "Object.new"
+  allocate_allocate: "Object.allocate"
 loop_count: 100000
diff --git a/benchmark/object_class.yml b/benchmark/object_class.yml
new file mode 100644
index 0000000000..1e5409d1e2
--- /dev/null
+++ b/benchmark/object_class.yml
@@ -0,0 +1,40 @@
+prelude: |
+  def get_class(obj)
+    i = 10_000
+    while i > 0
+      i -= 1
+      # 100 times per loop
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+      obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class; obj.class;
+    end
+  end
+
+  class Obj
+  end
+  obj = Obj.new
+
+  singleton = Obj.new
+  def singleton.bar
+  end
+
+  extended = Obj.new
+  2.times do
+    extended.extend Module.new
+  end
+
+  immediate = 1.4
+benchmark:
+  obj: get_class(obj)
+  extended: get_class(extended)
+  singleton: get_class(singleton)
+  immediate: get_class(immediate)
+loop_count: 1000
diff --git a/benchmark/object_id.yml b/benchmark/object_id.yml
new file mode 100644
index 0000000000..2bd52b923f
--- /dev/null
+++ b/benchmark/object_id.yml
@@ -0,0 +1,4 @@
+benchmark:
+  baseline: "Object.new"
+  object_id: "Object.new.object_id"
+# loop_count: 100000
diff --git a/benchmark/ractor_string_fstring.yml b/benchmark/ractor_string_fstring.yml
new file mode 100644
index 0000000000..14b92d8fd8
--- /dev/null
+++ b/benchmark/ractor_string_fstring.yml
@@ -0,0 +1,18 @@
+type: lib/benchmark_driver/runner/ractor
+benchmark:
+  ractor_fstring_random: |
+    i = 0
+    str = "same".dup
+    while i < 2000000
+      -(i.to_s.freeze)
+      i += 1
+    end
+  ractor_fstring_same: |
+    i = 0
+    str = "same".dup
+    while i < 2000000
+      -str
+      i += 1
+    end
+loop_count: 1
+ractor: 4
diff --git a/benchmark/range_bsearch_bignum.yml b/benchmark/range_bsearch_bignum.yml
new file mode 100644
index 0000000000..5730c93fcf
--- /dev/null
+++ b/benchmark/range_bsearch_bignum.yml
@@ -0,0 +1,10 @@
+prelude: |
+  first = 2**100
+  last = 2**1000
+  mid = (first + last) / 2
+  r = first..last
+
+benchmark:
+  first: r.bsearch { |x| x >= first }
+  mid: r.bsearch { |x| x >= mid }
+  last: r.bsearch { |x| x >= last }
diff --git a/benchmark/range_bsearch_endpointless.yml b/benchmark/range_bsearch_endpointless.yml
new file mode 100644
index 0000000000..8d7bedb662
--- /dev/null
+++ b/benchmark/range_bsearch_endpointless.yml
@@ -0,0 +1,21 @@
+prelude: |
+  re = (1..)
+  rb = (..0)
+
+benchmark:
+  'endless 10**0': re.bsearch { |x| x >= 1 }
+  'endless 10**1': re.bsearch { |x| x >= 10 }
+  'endless 10**2': re.bsearch { |x| x >= 100 }
+  'endless 10**3': re.bsearch { |x| x >= 1000 }
+  'endless 10**4': re.bsearch { |x| x >= 10000 }
+  'endless 10**5': re.bsearch { |x| x >= 100000 }
+  'endless 10**10': re.bsearch { |x| x >= 10000000000 }
+  'endless 10**100': re.bsearch { |x| x >= 10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 }
+  'beginless -10**0': rb.bsearch { |x| x >= -1 }
+  'beginless -10**1': rb.bsearch { |x| x >= -10 }
+  'beginless -10**2': rb.bsearch { |x| x >= -100 }
+  'beginless -10**3': rb.bsearch { |x| x >= -1000 }
+  'beginless -10**4': rb.bsearch { |x| x >= -10000 }
+  'beginless -10**5': rb.bsearch { |x| x >= -100000 }
+  'beginless -10**10': rb.bsearch { |x| x >= -10000000000 }
+  'beginless -10**100': rb.bsearch { |x| x >= -10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 }
diff --git a/benchmark/range_bsearch_fixnum.yml b/benchmark/range_bsearch_fixnum.yml
new file mode 100644
index 0000000000..59416531b9
--- /dev/null
+++ b/benchmark/range_bsearch_fixnum.yml
@@ -0,0 +1,10 @@
+prelude: |
+  first = 1
+  last = 10000
+  mid = (first + last) / 2
+  r = first..last
+
+benchmark:
+  first: r.bsearch { |x| x >= first }
+  mid: r.bsearch { |x| x >= mid }
+  last: r.bsearch { |x| x >= last }
diff --git a/benchmark/range_count.yml b/benchmark/range_count.yml
new file mode 100644
index 0000000000..58f53a0236
--- /dev/null
+++ b/benchmark/range_count.yml
@@ -0,0 +1,11 @@
+prelude: |
+  r_1 = 1..1
+  r_1k = 1..1000
+  r_1m = 1..1000000
+  r_str = 'a'..'z'
+
+benchmark:
+  'int 1': r_1.count
+  'int 1K': r_1k.count
+  'int 1M': r_1m.count
+  string: r_str.count
diff --git a/benchmark/range_min.yml b/benchmark/range_min.yml
new file mode 100644
index 0000000000..9e60dd7308
--- /dev/null
+++ b/benchmark/range_min.yml
@@ -0,0 +1,2 @@
+benchmark:
+  - (1..10).min
diff --git a/benchmark/range_overlap.yml b/benchmark/range_overlap.yml
new file mode 100644
index 0000000000..700a00053c
--- /dev/null
+++ b/benchmark/range_overlap.yml
@@ -0,0 +1,19 @@
+prelude: |
+  class Range
+    unless method_defined?(:overlap?)
+      def overlap?(other)
+        other.begin == self.begin || cover?(other.begin) || other.cover?(self.begin)
+      end
+    end
+  end
+
+benchmark:
+  - (2..3).overlap?(1..1)
+  - (2..3).overlap?(2..4)
+  - (2..3).overlap?(4..5)
+  - (2..3).overlap?(2..1)
+  - (2..3).overlap?(0..1)
+  - (2..3).overlap?(...1)
+  - (2...3).overlap?(..2)
+  - (2...3).overlap?(3...)
+  - (2..3).overlap?('a'..'d')
diff --git a/benchmark/range_reverse_each.yml b/benchmark/range_reverse_each.yml
new file mode 100644
index 0000000000..a32efeccc6
--- /dev/null
+++ b/benchmark/range_reverse_each.yml
@@ -0,0 +1,16 @@
+prelude: |
+  rf_1 = 0..1
+  rf_1k = 0..1000
+  rf_1m = 0..1000000
+  big = 2**1000
+  rb_1 = big..big+1
+  rb_1k = big..big+1000
+  rb_1m = big..big+1000000
+
+benchmark:
+  "Fixnum 1": rf_1.reverse_each { _1 }
+  "Fixnum 1K": rf_1k.reverse_each { _1 }
+  "Fixnum 1M": rf_1m.reverse_each { _1 }
+  "Bignum 1": rb_1.reverse_each { _1 }
+  "Bignum 1K": rb_1k.reverse_each { _1 }
+  "Bignum 1M": rb_1m.reverse_each { _1 }
diff --git a/benchmark/realpath.yml b/benchmark/realpath.yml
index 90a029d5b9..6b6a4836b0 100644
--- a/benchmark/realpath.yml
+++ b/benchmark/realpath.yml
@@ -12,6 +12,9 @@ prelude: |
   relative_dir = 'b/c'
   absolute_dir = File.join(pwd, relative_dir)
   file_dir = 'c'
+teardown: |
+  require 'fileutils'
+  FileUtils.rm_rf('b')
 benchmark:
   relative_nil: "f.realpath(relative, nil)"
   absolute_nil: "f.realpath(absolute, nil)"
diff --git a/benchmark/regexp_dup.yml b/benchmark/regexp_dup.yml
new file mode 100644
index 0000000000..52f89991cd
--- /dev/null
+++ b/benchmark/regexp_dup.yml
@@ -0,0 +1,6 @@
+prelude: |
+  str = "a" * 1000
+  re = Regexp.new(str)
+
+benchmark:
+  dup: re.dup
diff --git a/benchmark/regexp_new.yml b/benchmark/regexp_new.yml
new file mode 100644
index 0000000000..bc9ab3ca21
--- /dev/null
+++ b/benchmark/regexp_new.yml
@@ -0,0 +1,7 @@
+prelude: |
+  str = "a" * 1000
+  re = Regexp.new(str)
+
+benchmark:
+  string: Regexp.new(str)
+  regexp: Regexp.new(re)
diff --git a/benchmark/scan.yaml b/benchmark/scan.yaml
new file mode 100644
index 0000000000..62ad1d6862
--- /dev/null
+++ b/benchmark/scan.yaml
@@ -0,0 +1,16 @@
+prelude: |
+  $LOAD_PATH.unshift(File.expand_path("lib"))
+  require "strscan"
+  str = "test string"
+  scanner = StringScanner.new(str)
+  str = "test"
+  reg = /test/
+benchmark:
+  check(reg): |
+    scanner.check(reg)
+  check(str): |
+    scanner.check(str)
+  match?(reg): |
+    scanner.match?(reg)
+  match?(str): |
+    scanner.match?(str)
diff --git a/benchmark/search.yaml b/benchmark/search.yaml
new file mode 100644
index 0000000000..42a50c90e6
--- /dev/null
+++ b/benchmark/search.yaml
@@ -0,0 +1,16 @@
+prelude: |
+  $LOAD_PATH.unshift(File.expand_path("lib"))
+  require "strscan"
+  str = "test string"
+  scanner = StringScanner.new(str)
+  str = "string"
+  reg = /string/
+benchmark:
+  check_until(reg): |
+    scanner.check_until(reg)
+  check_until(str): |
+    scanner.check_until(str)
+  exist?(reg): |
+    scanner.exist?(reg)
+  exist?(str): |
+    scanner.exist?(str)
diff --git a/benchmark/set.yml b/benchmark/set.yml
new file mode 100644
index 0000000000..061509cb1f
--- /dev/null
+++ b/benchmark/set.yml
@@ -0,0 +1,261 @@
+prelude: |
+  # First 1000 digits of pi
+  pi = <<~END.gsub(/\D/, '')
+    31415926535897932384626433832795028841971693993751058209749445923078164062862089
+    98628034825342117067982148086513282306647093844609550582231725359408128481117450
+    28410270193852110555964462294895493038196442881097566593344612847564823378678316
+    52712019091456485669234603486104543266482133936072602491412737245870066063155881
+    74881520920962829254091715364367892590360011330530548820466521384146951941511609
+    43305727036575959195309218611738193261179310511854807446237996274956735188575272
+    48912279381830119491298336733624406566430860213949463952247371907021798609437027
+    70539217176293176752384674818467669405132000568127145263560827785771342757789609
+    17363717872146844090122495343014654958537105079227968925892354201995611212902196
+    08640344181598136297747713099605187072113499999983729780499510597317328160963185
+    95024459455346908302642522308253344685035261931188171010003137838752886587533208
+    38142061717766914730359825349042875546873115956286388235378759375195778185778053
+    21712268066130019278766111959092164201989380952572010654505906988788448549
+  END
+  array1 = 10.times.flat_map do |i|
+    pi[i...].chars.each_slice(10).map(&:join)
+  end
+  array2 = array1.map(&:reverse)
+  array1.map!(&:to_i)
+  array2.map!(&:to_i)
+  a1 = array1[...10]
+  a2 = array1[...100]
+  a3 = array1
+  oa1 = array2[...10]
+  oa2 = array2[...100]
+  oa3 = array2
+  s0 = Set.new
+  s0 = Set.new
+  s1 = Set.new(a1)
+  s2 = Set.new(a2)
+  s3 = Set.new(a3)
+  o0 = Set.new
+  o1 = Set.new(array2[...10])
+  o2 = Set.new(array2[...100])
+  o3 = Set.new(array2)
+  d0 = s0.dup
+  d1 = s1.dup
+  d2 = s2.dup
+  d3 = s3.dup
+  ss1 = s1 - a1[-1..-1]
+  ss2 = s2 - a2[-1..-1]
+  ss3 = s3 - a3[-1..-1]
+  os1 = o1 - oa1[-1..-1]
+  os2 = o2 - oa2[-1..-1]
+  os3 = o3 - oa3[-1..-1]
+  member = a1.first
+  cbi = s0.dup.compare_by_identity
+  ns = Set[s3, o3, d3]
+  set_subclass = Class.new(Set)
+
+benchmark:
+  new_0: Set.new
+  new_10: Set.new(a1)
+  new_100: Set.new(a2)
+  new_1000: Set.new(a3)
+  aref_0: Set[]
+  aref_10: Set[*a1]
+  aref_100: Set[*a2]
+  aref_1000: Set[*a3]
+  amp_0: s0 & o0
+  amp_10: s1 & o1
+  amp_100: s2 & o2
+  amp_1000: s3 & o3
+  amp_same_0: s0 & d0
+  amp_same_10: s1 & d1
+  amp_same_100: s2 & d2
+  amp_same_1000: s3 & d3
+  minus_0: s0 - o0
+  minus_10: s1 - o1
+  minus_100: s2 - o2
+  minus_1000: s3 - o3
+  minus_same_0: s0 - d0
+  minus_same_10: s1 - d1
+  minus_same_100: s2 - d2
+  minus_same_1000: s3 - d3
+  spaceship_0: s0 <=> o0
+  spaceship_diff_10: s1 <=> o1
+  spaceship_diff_100: s2 <=> o2
+  spaceship_diff_1000: s2 <=> o3
+  spaceship_sub_10: s1 <=> ss1
+  spaceship_sub_100: s2 <=> ss2
+  spaceship_sub_1000: s2 <=> ss3
+  spaceship_sup_10: ss1 <=> s1
+  spaceship_sup_100: ss2 <=> s2
+  spaceship_sup_1000: ss2 <=> s3
+  eq_0: s0 == o0
+  eq_10: s1 == o1
+  eq_100: s2 == o2
+  eq_1000: s3 == o3
+  eq_same_0: s0 == d0
+  eq_same_10: s1 == d1
+  eq_same_100: s2 == d2
+  eq_same_1000: s3 == d3
+  xor_0: s0 ^ o0
+  xor_10: s1 ^ o1
+  xor_100: s2 ^ o2
+  xor_1000: s3 ^ o3
+  xor_same_0: s0 ^ d0
+  xor_same_10: s1 ^ d1
+  xor_same_100: s2 ^ d2
+  xor_same_1000: s3 ^ d3
+  pipe_0: s0 | o0
+  pipe_10: s1 | o1
+  pipe_100: s2 | o2
+  pipe_1000: s3 | o3
+  pipe_same_0: s0 | d0
+  pipe_same_10: s1 | d1
+  pipe_same_100: s2 | d2
+  pipe_same_1000: s3 | d3
+  add: a3.each { s0.add(it) }
+  add_exist: a3.each { s3.add(it) }
+  addq: a3.each { s0.add?(it) }
+  addq_exist: a3.each { s3.add?(it) }
+  classify_0: s0.classify { it }
+  classify_10: s1.classify { it & 2 }
+  classify_100: s2.classify { it & 8 }
+  classify_1000: s3.classify { it & 32 }
+  clear: s0.clear
+  collect_0: s0.collect! { it }
+  collect_10: s1.collect! { it }
+  collect_100: s2.collect! { it }
+  collect_1000: s3.collect! { it }
+  compare_by_identity_0: s0.dup.compare_by_identity
+  compare_by_identity_10: s1.dup.compare_by_identity
+  compare_by_identity_100: s2.dup.compare_by_identity
+  compare_by_identity_1000: s3.dup.compare_by_identity
+  compare_by_identityq_false: s0.compare_by_identity?
+  compare_by_identityq_true: cbi.compare_by_identity?
+  clone_0: s0.clone
+  clone_10: s1.clone
+  clone_100: s2.clone
+  clone_1000: s3.clone
+  delete: a3.each { s3.delete(it) }
+  delete_not_exist: a3.each { o3.delete(it) }
+  deleteq: a3.each { s3.delete?(it) }
+  deleteq_not_exist: a3.each { o3.delete?(it) }
+  delete_if_0: s0.delete_if { it }
+  delete_if_10: s1.delete_if { it & 2 == 0 }
+  delete_if_100: s2.delete_if { it & 2 == 0 }
+  delete_if_1000: s3.delete_if { it & 2 == 0 }
+  disjoint_0: s0.disjoint? o0
+  disjoint_10: s1.disjoint? o1
+  disjoint_100: s2.disjoint? o2
+  disjoint_1000: s3.disjoint? o3
+  disjoint_same_0: s0.disjoint? d0
+  disjoint_same_10: s1.disjoint? d1
+  disjoint_same_100: s2.disjoint? d2
+  disjoint_same_1000: s3.disjoint? d3
+  divide_1arity_0: s0.divide { true }
+  divide_1arity_10: s1.divide { it & 2 }
+  divide_1arity_100: s2.divide { it & 8 }
+  divide_1arity_1000: s3.divide { it & 32 }
+  divide_2arity_0: s0.divide { true }
+  divide_2arity_10: s1.divide { (_1 & 2) == (_2 & 2) }
+  divide_2arity_100: s2.divide { (_1 & 8) == (_2 & 8) }
+  divide_2arity_1000: s3.divide { (_1 & 32) == (_2 & 32) }
+  dup_0: s0.dup
+  dup_10: s1.dup
+  dup_100: s2.dup
+  dup_1000: s3.dup
+  each_0: s0.each { it }
+  each_10: s1.each { it }
+  each_100: s2.each { it }
+  each_1000: s3.each { it }
+  empty_true: s0.empty?
+  empty_false: s3.empty?
+  flatten: ns.flatten
+  flattenb: ns.flatten!
+  include_true_0: s0.include? member
+  include_true_10: s1.include? member
+  include_true_100: s2.include? member
+  include_true_1000: s3.include? member
+  include_false_0: s0.include?(-1)
+  include_false_10: s1.include?(-1)
+  include_false_100: s2.include?(-1)
+  include_false_1000: s3.include?(-1)
+  intersect_0: s0.intersect? o0
+  intersect_10: s1.intersect? o1
+  intersect_100: s2.intersect? o2
+  intersect_1000: s3.intersect? o3
+  intersect_same_0: s0.intersect? d0
+  intersect_same_10: s1.intersect? d1
+  intersect_same_100: s2.intersect? d2
+  intersect_same_1000: s3.intersect? d3
+  join_0: s0.join
+  join_10: s1.join
+  join_100: s2.join
+  join_1000: s3.join
+  join_arg_0: s0.join ""
+  join_arg_10: s1.join ""
+  join_arg_100: s2.join ""
+  join_arg_1000: s3.join ""
+  keep_if_0: s0.keep_if { it }
+  keep_if_10: s1.keep_if { it & 2 == 0 }
+  keep_if_100: s2.keep_if { it & 2 == 0 }
+  keep_if_1000: s3.keep_if { it & 2 == 0 }
+  merge_set: s0.dup.merge(s3, o3)
+  merge_enum: s0.dup.merge(array1, array2)
+  proper_subset_0: s0.proper_subset? s0
+  proper_subset_10: s1.proper_subset? ss1
+  proper_subset_100: s2.proper_subset? ss2
+  proper_subset_1000: s3.proper_subset? ss3
+  proper_subset_false_10: s1.proper_subset? os1
+  proper_subset_false_100: s2.proper_subset? os2
+  proper_subset_false_1000: s3.proper_subset? os3
+  proper_superset_0: s0.proper_superset? s0
+  proper_superset_10: ss1.proper_superset? s1
+  proper_superset_100: ss2.proper_superset? s2
+  proper_superset_1000: ss3.proper_superset? s3
+  proper_superset_false_10: os1.proper_superset? s1
+  proper_superset_false_100: os2.proper_superset? s2
+  proper_superset_false_1000: os3.proper_superset? s3
+  reject_0: s0.reject! { it }
+  reject_10: s1.reject! { it & 2 == 0 }
+  reject_100: s2.reject! { it & 2 == 0 }
+  reject_1000: s3.reject! { it & 2 == 0 }
+  replace_0: s = Set.new; array1.each { s.replace(s0) }
+  replace_10: s = Set.new; array1.each { s.replace(s1) }
+  replace_100: s = Set.new; array1.each { s.replace(s2) }
+  replace_1000: s = Set.new; array1.each { s.replace(s3) }
+  reset_0: s0.reset
+  reset_10: s1.reset
+  reset_100: s2.reset
+  reset_1000: s3.reset
+  select_0: s0.select! { it }
+  select_10: s1.select! { it & 2 == 0 }
+  select_100: s2.select! { it & 2 == 0 }
+  select_1000: s3.select! { it & 2 == 0 }
+  size_0: s0.size
+  size_10: s1.size
+  size_100: s2.size
+  size_1000: s3.size
+  subtract_set: s3.dup.subtract(os3)
+  subtract_enum: s3.dup.subtract(oa3)
+  subtract_same_set: s3.dup.subtract(s3)
+  subtract_same_enum: s3.dup.subtract(a3)
+  subset_0: s0.subset? s0
+  subset_10: s1.subset? ss1
+  subset_100: s2.subset? ss2
+  subset_1000: s3.subset? ss3
+  subset_false_10: s1.subset? os1
+  subset_false_100: s2.subset? os2
+  subset_false_1000: s3.subset? os3
+  superset_0: s0.superset? s0
+  superset_10: ss1.superset? s1
+  superset_100: ss2.superset? s2
+  superset_1000: ss3.superset? s3
+  superset_false_10: os1.superset? s1
+  superset_false_100: os2.superset? s2
+  superset_false_1000: os3.superset? s3
+  to_a_0: s0.to_a
+  to_a_10: s1.to_a
+  to_a_100: s2.to_a
+  to_a_1000: s3.to_a
+  to_set_0: s0.to_set
+  to_set_10: s1.to_set
+  to_set_100: s2.to_set
+  to_set_1000: s3.to_set
diff --git a/benchmark/so_count_words.yml b/benchmark/so_count_words.yml
index 99683505f9..f7322a8541 100644
--- a/benchmark/so_count_words.yml
+++ b/benchmark/so_count_words.yml
@@ -15,13 +15,13 @@ prelude: |
   Newsgroups:   rec.games.roguelike.nethack
   X-Mailer:     Mozilla 1.1N (Macintosh; I; 68K)
 
-  Hello there, Izchak Miller was my father.  When I was younger I spent 
-  many a night, hunched over the keyboard with a cup of tea, playing 
-  nethack with him and my brother.  my dad was a philosopher with a strong 
-  weakness for fantasy/sci fi.  I remember when he started to get involved 
-  with the Nethack team- my brother's Dungeons and Dragons monster book 
-  found a regular place beside my dad's desk. it's nice to see him living 
-  on in the game he loved so much :-).  
+  Hello there,  Izchak Miller was my  father.  When I was  younger I spent
+  many  a night,  hunched over  the keyboard  with a  cup of  tea, playing
+  nethack with him and my brother.  my dad was a philosopher with a strong
+  weakness for fantasy/sci fi.  I remember when he started to get involved
+  with the  Nethack team- my  brother's Dungeons and Dragons  monster book
+  found a regular place beside my dad's  desk. it's nice to see him living
+  on in the game he loved so much :-).
                                                                     Tamar Miller
 
   The following is a really long word of 5000 characters:
@@ -38,8 +38,9 @@ prelude: |
       13.times{
         data << data
       }
-      open(wcinput, 'w'){|f| f.write data}
+      File.write(wcinput, data)
     end
+    at_exit {File.unlink(wcinput) rescue nil}
   end
 
   prepare_wc_input(wc_input_base)
@@ -49,16 +50,16 @@ benchmark:
     # $Id: wc-ruby.code,v 1.4 2004/11/13 07:43:32 bfulgham Exp $
     # http://www.bagley.org/~doug/shootout/
     # with help from Paul Brannan
-    input = open(File.join(File.dirname($0), 'wc.input'), 'rb')
 
     nl = nw = nc = 0
-    while true
-      tmp = input.read(4096) or break
-      data = tmp << (input.gets || "")
-      nc += data.length
-      nl += data.count("\n")
-      ((data.strip! || data).tr!("\n", " ") || data).squeeze!
-      nw += data.count(" ") + 1
+    File.open(File.join(File.dirname($0), 'wc.input'), 'rb') do |input|
+      while tmp = input.read(4096)
+        data = tmp << (input.gets || "")
+        nc += data.length
+        nl += data.count("\n")
+        ((data.strip! || data).tr!("\n", " ") || data).squeeze!
+        nw += data.count(" ") + 1
+      end
     end
     # STDERR.puts "#{nl} #{nw} #{nc}"
 
diff --git a/benchmark/so_meteor_contest.rb b/benchmark/so_meteor_contest.rb
index 8c136baa6c..d8c8e3ab9c 100644
--- a/benchmark/so_meteor_contest.rb
+++ b/benchmark/so_meteor_contest.rb
@@ -447,7 +447,7 @@ end
 #   as an inverse.  The inverse will ALWAYS be 3 one of the piece configurations that is exactly 3 rotations away
 #   (an odd number).  Checking even vs odd then produces a higher probability of finding more pieces earlier
 #   in the cycle.  We still need to keep checking all the permutations, but our probability of finding one will
-#   diminsh over time.  Since we are TOLD how many to search for this lets us exit before checking all pieces
+#   diminish over time.  Since we are TOLD how many to search for this lets us exit before checking all pieces
 #   this bennifit is very great when seeking small numbers of solutions and is 0 when looking for more than the
 #   maximum number
 def find_top( rotation_skip)
diff --git a/benchmark/string_casecmp.yml b/benchmark/string_casecmp.yml
index 2354040a04..88a3555c8a 100644
--- a/benchmark/string_casecmp.yml
+++ b/benchmark/string_casecmp.yml
@@ -20,7 +20,9 @@ benchmark:
   casecmp-10: lstr10.casecmp(ustr10)
   casecmp-100: lstr100.casecmp(ustr100)
   casecmp-1000: lstr1000.casecmp(ustr1000)
+  casecmp-1000vs10: lstr1000.casecmp(ustr10)
   casecmp-nonascii1: lnonascii1.casecmp(unonascii1)
   casecmp-nonascii10: lnonascii10.casecmp(unonascii10)
   casecmp-nonascii100: lnonascii100.casecmp(unonascii100)
   casecmp-nonascii1000: lnonascii1000.casecmp(unonascii1000)
+  casecmp-nonascii1000vs10: lnonascii1000.casecmp(unonascii10)
diff --git a/benchmark/string_concat.yml b/benchmark/string_concat.yml
index e65c00cca9..f11f95ee9a 100644
--- a/benchmark/string_concat.yml
+++ b/benchmark/string_concat.yml
@@ -1,6 +1,8 @@
 prelude: |
   CHUNK = "a" * 64
   UCHUNK = "é" * 32
+  SHORT = "a" * (GC::INTERNAL_CONSTANTS[:BASE_SLOT_SIZE] / 2)
+  LONG = "a" * (GC::INTERNAL_CONSTANTS[:BASE_SLOT_SIZE] * 2)
   GC.disable # GC causes a lot of variance
 benchmark:
   binary_concat_7bit: |
@@ -43,3 +45,7 @@ benchmark:
       "#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}" \
       "#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}" \
       "#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}#{CHUNK}"
+  interpolation_same_heap: |
+    buffer = "#{SHORT}#{SHORT}"
+  interpolation_switching_heaps: |
+    buffer = "#{SHORT}#{LONG}"
diff --git a/benchmark/string_dup.yml b/benchmark/string_dup.yml
new file mode 100644
index 0000000000..90793f9f2a
--- /dev/null
+++ b/benchmark/string_dup.yml
@@ -0,0 +1,7 @@
+prelude: |
+  # frozen_string_literal: true
+benchmark:
+  uplus: |
+    +"A"
+  dup: |
+    "A".dup
diff --git a/benchmark/string_fstring.yml b/benchmark/string_fstring.yml
new file mode 100644
index 0000000000..cafef1f3fe
--- /dev/null
+++ b/benchmark/string_fstring.yml
@@ -0,0 +1,16 @@
+benchmark:
+  fstring_random: |
+    i = 0
+    str = "same".dup
+    while i < 5_000_000
+      -(i.to_s.freeze)
+      i += 1
+    end
+  fstring_same: |
+    i = 0
+    str = "same".dup
+    while i < 10_000_000
+      -str
+      i += 1
+    end
+loop_count: 1
diff --git a/benchmark/string_gsub.yml b/benchmark/string_gsub.yml
new file mode 100644
index 0000000000..0f964337dd
--- /dev/null
+++ b/benchmark/string_gsub.yml
@@ -0,0 +1,43 @@
+prelude: |
+  # frozen_string_literal: true
+  STR = ((("a" * 31) + "<") * 1000).freeze
+  STR_UNICODE = ((("a" * 30) + "\u2028") * 1000).freeze
+  ESCAPED_CHARS_BINARY = {
+    "\u2028".b => '\u2028'.b,
+    "\u2029".b => '\u2029'.b,
+    ">".b => '\u003e'.b.freeze,
+    "<".b => '\u003c'.b.freeze,
+    "&".b => '\u0026'.b.freeze,
+  }
+  BINARY_PATTERN = Regexp.union(ESCAPED_CHARS_BINARY.keys)
+
+  ESCAPED_CHARS = {
+    "\u2028" => '\u2028',
+    "\u2029" => '\u2029',
+    ">" => '\u003e',
+    "<" => '\u003c',
+    "&" => '\u0026',
+  }
+  ESCAPE_PATTERN = Regexp.union(ESCAPED_CHARS.keys)
+
+
+benchmark:
+  escape: |
+    str = STR.dup
+    str.gsub!(ESCAPE_PATTERN, ESCAPED_CHARS)
+    str
+
+  escape_bin: |
+    str = STR.b
+    str.gsub!(BINARY_PATTERN, ESCAPED_CHARS_BINARY)
+    str.force_encoding(Encoding::UTF_8)
+
+  escape_utf8: |
+    str = STR_UNICODE.dup
+    str.gsub!(ESCAPE_PATTERN, ESCAPED_CHARS)
+    str
+
+  escape_utf8_bin: |
+    str = STR_UNICODE.b
+    str.gsub!(BINARY_PATTERN, ESCAPED_CHARS_BINARY)
+    str.force_encoding(Encoding::UTF_8)
diff --git a/benchmark/string_rpartition.yml b/benchmark/string_rpartition.yml
new file mode 100644
index 0000000000..37e9d1b071
--- /dev/null
+++ b/benchmark/string_rpartition.yml
@@ -0,0 +1,18 @@
+prelude: |
+  str1 = [*"a".."z",*"0".."9"].join("")
+  str10 = str1 * 10 + ":"
+  str100 = str1 * 100 + ":"
+  str1000 = str1 * 1000 + ":"
+  nonascii1 = [*"\u{e0}".."\u{ff}"].join("")
+  nonascii10 = nonascii1 * 10 + ":"
+  nonascii100 = nonascii1 * 100 + ":"
+  nonascii1000 = nonascii1 * 1000 + ":"
+benchmark:
+  rpartition-1: str1.rpartition(":")
+  rpartition-10: str10.rpartition(":")
+  rpartition-100: str100.rpartition(":")
+  rpartition-1000: str1000.rpartition(":")
+  rpartition-nonascii1: nonascii1.rpartition(":")
+  rpartition-nonascii10: nonascii10.rpartition(":")
+  rpartition-nonascii100: nonascii100.rpartition(":")
+  rpartition-nonascii1000: nonascii1000.rpartition(":")
diff --git a/benchmark/struct_accessor.yml b/benchmark/struct_accessor.yml
new file mode 100644
index 0000000000..d95240e2dd
--- /dev/null
+++ b/benchmark/struct_accessor.yml
@@ -0,0 +1,37 @@
+prelude: |
+  C = Struct.new(:x) do
+    def initialize(...)
+      super
+      @ivar = 42
+    end
+
+    attr_accessor :ivar
+
+    class_eval <<-END
+      def r
+        #{'x;'*256}
+      end
+      def w
+        #{'self.x = nil;'*256}
+      end
+      def rm
+        m = method(:x)
+        #{'m.call;'*256}
+      end
+      def wm
+        m = method(:x=)
+        #{'m.call(nil);'*256}
+      end
+      def r_ivar
+        #{'ivar;'*256}
+      end
+    END
+  end
+  C.new(nil) # ensure common shape is known
+  obj = C.new(nil)
+benchmark:
+  member_reader: "obj.r"
+  member_writer: "obj.w"
+  member_reader_method: "obj.rm"
+  member_writer_method: "obj.wm"
+  ivar_reader: "obj.r_ivar"
diff --git a/benchmark/time_now.yml b/benchmark/time_now.yml
index f6d6a31489..9336877cd4 100644
--- a/benchmark/time_now.yml
+++ b/benchmark/time_now.yml
@@ -1,3 +1,4 @@
 benchmark:
   - 'Time.now'
   - 'Time.now(in: "+09:00")'
+  - 'Time.now.year'
diff --git a/benchmark/time_parse.yml b/benchmark/time_parse.yml
index a6d6948b9c..6060b58bc6 100644
--- a/benchmark/time_parse.yml
+++ b/benchmark/time_parse.yml
@@ -6,3 +6,5 @@ benchmark:
   - Time.iso8601(iso8601)
   - Time.parse(iso8601)
   - Time.parse(inspect)
+  - Time.new(iso8601) rescue Time.iso8601(iso8601)
+  - Time.new(inspect) rescue Time.parse(inspect)
diff --git a/benchmark/time_strftime.yml b/benchmark/time_strftime.yml
new file mode 100644
index 0000000000..28f62aec87
--- /dev/null
+++ b/benchmark/time_strftime.yml
@@ -0,0 +1,7 @@
+prelude: |
+  # frozen_string_literal: true
+  time = Time.now
+benchmark:
+  - time.strftime("%FT%T")     # 19B
+  - time.strftime("%FT%T.%3N") # 23B
+  - time.strftime("%FT%T.%6N") # 26B
diff --git a/benchmark/time_xmlschema.yml b/benchmark/time_xmlschema.yml
new file mode 100644
index 0000000000..654e5cfcbc
--- /dev/null
+++ b/benchmark/time_xmlschema.yml
@@ -0,0 +1,27 @@
+prelude: |
+  # frozen_string_literal
+  unless Time.method_defined?(:xmlschema)
+    class Time
+      def xmlschema(fraction_digits=0)
+        fraction_digits = fraction_digits.to_i
+        s = strftime("%FT%T")
+        if fraction_digits > 0
+          s << strftime(".%#{fraction_digits}N")
+        end
+        s << (utc? ? 'Z' : strftime("%:z"))
+      end
+    end
+  end
+  time = Time.now
+  utc_time = Time.now.utc
+  fraction_sec = Time.at(123456789.quo(9999999999)).getlocal("+09:00")
+  future_time = Time.utc(10000)
+benchmark:
+  - time.xmlschema
+  - utc_time.xmlschema
+  - time.xmlschema(6)
+  - utc_time.xmlschema(6)
+  - time.xmlschema(9)
+  - utc_time.xmlschema(9)
+  - fraction_sec.xmlschema(10)
+  - future_time.xmlschema
diff --git a/benchmark/vm_call_bmethod.yml b/benchmark/vm_call_bmethod.yml
new file mode 100644
index 0000000000..40136e5aa4
--- /dev/null
+++ b/benchmark/vm_call_bmethod.yml
@@ -0,0 +1,37 @@
+prelude: |
+  define_method(:a0){}
+  define_method(:a1){|a| a}
+  define_method(:s){|*a| a}
+  define_method(:b){|kw: 1| kw}
+
+  t0 = 0.times.to_a
+  t1 = 1.times.to_a
+  t10 = 10.times.to_a
+  t100 = 100.times.to_a
+  kw = {kw: 2}
+benchmark:
+  bmethod_simple_0: |
+    a0
+  bmethod_simple_1: |
+    a1(1)
+  bmethod_simple_0_splat: |
+    a0(*t0)
+  bmethod_simple_1_splat: |
+    a1(*t1)
+  bmethod_no_splat: |
+    s
+  bmethod_0_splat: |
+    s(*t0)
+  bmethod_1_splat: |
+    s(*t1)
+  bmethod_10_splat: |
+    s(*t10)
+  bmethod_100_splat: |
+    s(*t100)
+  bmethod_kw: |
+    b(kw: 1)
+  bmethod_no_kw: |
+    b
+  bmethod_kw_splat: |
+    b(**kw)
+loop_count: 6000000
diff --git a/benchmark/vm_call_kw_and_kw_splat.yml b/benchmark/vm_call_kw_and_kw_splat.yml
new file mode 100644
index 0000000000..aa6e549e0c
--- /dev/null
+++ b/benchmark/vm_call_kw_and_kw_splat.yml
@@ -0,0 +1,25 @@
+prelude: |
+  h1, h10, h100, h1000 = [1, 10, 100, 1000].map do |n|
+    h = {kw: 1}
+    n.times{|i| h[i.to_s.to_sym] = i}
+    h
+  end
+  eh = {}
+  def kw(kw: nil, **kws) end
+benchmark:
+  1: |
+    kw(**h1)
+  1_mutable: |
+    kw(**eh, **h1)
+  10: |
+    kw(**h10)
+  10_mutable: |
+    kw(**eh, **h10)
+  100: |
+    kw(**h100)
+  100_mutable: |
+    kw(**eh, **h100)
+  1000: |
+    kw(**h1000)
+  1000_mutable: |
+    kw(**eh, **h1000)
diff --git a/benchmark/vm_call_method_missing.yml b/benchmark/vm_call_method_missing.yml
new file mode 100644
index 0000000000..f890796f11
--- /dev/null
+++ b/benchmark/vm_call_method_missing.yml
@@ -0,0 +1,62 @@
+prelude: |
+  class A0
+    def method_missing(m); m end
+  end
+  class A1
+    def method_missing(m, a) a; end
+  end
+  class S
+    def method_missing(m, *a) a; end
+  end
+  class B
+    def method_missing(m, kw: 1) kw end
+  end
+  class SB
+    def method_missing(m, *a, kw: 1) kw end
+  end
+
+  t0 = 0.times.to_a
+  t1 = 1.times.to_a
+  t10 = 10.times.to_a
+  t200 = 200.times.to_a
+  kw = {kw: 2}
+
+  a0 = A0.new
+  a1 = A1.new
+  s = S.new
+  b = B.new
+  sb = SB.new
+benchmark:
+  method_missing_simple_0: |
+    a0.()
+  method_missing_simple_1: |
+    a1.x(1)
+  method_missing_simple_0_splat: |
+    a0.(*t0)
+  method_missing_simple_1_splat: |
+    a1.(*t1)
+  method_missing_no_splat: |
+    s.()
+  method_missing_0_splat: |
+    s.(*t0)
+  method_missing_1_splat: |
+    s.(*t1)
+  method_missing_10_splat: |
+    s.(*t10)
+  method_missing_200_splat: |
+    s.(*t200)
+  method_missing_kw: |
+    b.(kw: 1)
+  method_missing_no_kw: |
+    b.()
+  method_missing_kw_splat: |
+    b.(**kw)
+  method_missing_0_splat_kw: |
+    sb.(*t0, **kw)
+  method_missing_1_splat_kw: |
+    sb.(*t1, **kw)
+  method_missing_10_splat_kw: |
+    sb.(*t10, **kw)
+  method_missing_200_splat_kw: |
+    sb.(*t200, **kw)
+loop_count: 1000000
diff --git a/benchmark/vm_call_send_iseq.yml b/benchmark/vm_call_send_iseq.yml
new file mode 100644
index 0000000000..60ff23c475
--- /dev/null
+++ b/benchmark/vm_call_send_iseq.yml
@@ -0,0 +1,77 @@
+prelude: |
+  def a0; end
+  def a1(a) a; end
+  def s(*a) a; end
+  def b(kw: 1) kw end
+  def sb(*a, kw: 1) kw end
+
+  t0 = 0.times.to_a
+  t1 = 1.times.to_a
+  t10 = 10.times.to_a
+  t200 = 200.times.to_a
+
+  a0_t0 = [:a0, *t0]
+  a1_t1 = [:a1, *t1]
+  s_t0 = [:s, *t0]
+  s_t1 = [:s, *t1]
+  s_t10 = [:s, *t10]
+  s_t200 = [:s, *t200]
+  sb_t0 = [:sb, *t0]
+  sb_t1 = [:sb, *t1]
+  sb_t10 = [:sb, *t10]
+  sb_t200 = [:sb, *t200]
+  kw = {kw: 2}
+benchmark:
+  send_simple_0: |
+    send(:a0)
+  send_simple_1: |
+    send(:a1, 1)
+  send_simple_0_splat: |
+    send(:a0, *t0)
+  send_simple_1_splat: |
+    send(:a1, *t1)
+  send_simple_0_splat_comb: |
+    send(*a0_t0)
+  send_simple_1_splat_comb: |
+    send(*a1_t1)
+  send_no_splat: |
+    send(:s)
+  send_0_splat: |
+    send(:s, *t0)
+  send_1_splat: |
+    send(:s, *t1)
+  send_10_splat: |
+    send(:s, *t10)
+  send_200_splat: |
+    send(:s, *t200)
+  send_0_splat_comb: |
+    send(*s_t0)
+  send_1_splat_comb: |
+    send(*s_t1)
+  send_10_splat_comb: |
+    send(*s_t10)
+  send_200_splat_comb: |
+    send(*s_t200)
+  send_kw: |
+    send(:b, kw: 1)
+  send_no_kw: |
+    send(:b)
+  send_kw_splat: |
+    send(:b, **kw)
+  send_0_splat_kw: |
+    send(:sb, *t0, **kw)
+  send_1_splat_kw: |
+    send(:sb, *t1, **kw)
+  send_10_splat_kw: |
+    send(:sb, *t10, **kw)
+  send_200_splat_kw: |
+    send(:sb, *t200, **kw)
+  send_0_splat_comb_kw: |
+    send(*sb_t0, **kw)
+  send_1_splat_comb_kw: |
+    send(*sb_t1, **kw)
+  send_10_splat_comb_kw: |
+    send(*sb_t10, **kw)
+  send_200_splat_comb_kw: |
+    send(*sb_t200, **kw)
+loop_count: 3000000
diff --git a/benchmark/vm_call_symproc.yml b/benchmark/vm_call_symproc.yml
new file mode 100644
index 0000000000..16e0ac579e
--- /dev/null
+++ b/benchmark/vm_call_symproc.yml
@@ -0,0 +1,83 @@
+prelude: |
+  def self.a0; end
+  def self.a1(a) a; end
+  def self.s(*a) a; end
+  def self.b(kw: 1) kw end
+  def self.sb(*a, kw: 1) kw end
+
+  t0 = 0.times.to_a
+  t1 = 1.times.to_a
+  t10 = 10.times.to_a
+  t200 = 200.times.to_a
+
+  a0_t0 = [self, *t0]
+  a1_t1 = [self, *t1]
+  s_t0 = [self, *t0]
+  s_t1 = [self, *t1]
+  s_t10 = [self, *t10]
+  s_t200 = [self, *t200]
+  sb_t0 = [self, *t0]
+  sb_t1 = [self, *t1]
+  sb_t10 = [self, *t10]
+  sb_t200 = [self, *t200]
+  kw = {kw: 2}
+
+  a0 = :a0.to_proc
+  a1 = :a1.to_proc
+  s = :s.to_proc
+  b = :b.to_proc
+  sb = :sb.to_proc
+benchmark:
+  symproc_simple_0: |
+    a0.(self)
+  symproc_simple_1: |
+    a1.(self, 1)
+  symproc_simple_0_splat: |
+    a0.(self, *t0)
+  symproc_simple_1_splat: |
+    a1.(self, *t1)
+  symproc_simple_0_splat_comb: |
+    a0.(*a0_t0)
+  symproc_simple_1_splat_comb: |
+    a1.(*a1_t1)
+  symproc_no_splat: |
+    s.(self)
+  symproc_0_splat: |
+    s.(self, *t0)
+  symproc_1_splat: |
+    s.(self, *t1)
+  symproc_10_splat: |
+    s.(self, *t10)
+  symproc_200_splat: |
+    s.(self, *t200)
+  symproc_0_splat_comb: |
+    s.(*s_t0)
+  symproc_1_splat_comb: |
+    s.(*s_t1)
+  symproc_10_splat_comb: |
+    s.(*s_t10)
+  symproc_200_splat_comb: |
+    s.(*s_t200)
+  symproc_kw: |
+    b.(self, kw: 1)
+  symproc_no_kw: |
+    b.(self)
+  symproc_kw_splat: |
+    b.(self, **kw)
+  symproc_0_splat_kw: |
+    sb.(self, *t0, **kw)
+  symproc_1_splat_kw: |
+    sb.(self, *t1, **kw)
+  symproc_10_splat_kw: |
+    sb.(self, *t10, **kw)
+  symproc_200_splat_kw: |
+    sb.(self, *t200, **kw)
+  symproc_0_splat_comb_kw: |
+    sb.(*sb_t0, **kw)
+  symproc_1_splat_comb_kw: |
+    sb.(*sb_t1, **kw)
+  symproc_10_splat_comb_kw: |
+    sb.(*sb_t10, **kw)
+  symproc_200_splat_comb_kw: |
+    sb.(*sb_t200, **kw)
+loop_count: 1000000
diff --git a/benchmark/vm_freezeobj.yml b/benchmark/vm_freezeobj.yml
new file mode 100644
index 0000000000..69a795a354
--- /dev/null
+++ b/benchmark/vm_freezeobj.yml
@@ -0,0 +1,6 @@
+prelude: |
+ objs = 100000.times.map { Object.new }
+benchmark:
+  vm_freeze_obj: |
+    objs.map(&:freeze)
+loop_count: 600
diff --git a/benchmark/vm_ivar_get.yml b/benchmark/vm_ivar_get.yml
index 9174af6965..1e0dad665f 100644
--- a/benchmark/vm_ivar_get.yml
+++ b/benchmark/vm_ivar_get.yml
@@ -1,17 +1,75 @@
 prelude: |
   class Example
     def initialize
+      @levar = 1
       @v0 = 1
       @v1 = 2
       @v3 = 3
+    end
+
+    def get_value_loop
+      sum = 0
+
+      i = 0
+      while i < 100_000
+        # 10 times to de-emphasize loop overhead
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        i += 1
+      end
+
+      return sum
+    end
+
+    @levar = 1
+    @v0 = 1
+    @v1 = 2
+    @v3 = 3
+
+    def self.get_value_loop
+      sum = 0
+
+      i = 0
+      while i < 100_000
+        # 10 times to de-emphasize loop overhead
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        sum += @levar
+        i += 1
+      end
+
+      return sum
+    end
+  end
+
+  class GenExample < Time
+    def initialize
       @levar = 1
+      @v0 = 1
+      @v1 = 2
+      @v3 = 3
     end
 
     def get_value_loop
       sum = 0
 
       i = 0
-      while i < 1000000
+      while i < 100_000
         # 10 times to de-emphasize loop overhead
         sum += @levar
         sum += @levar
@@ -31,7 +89,12 @@ prelude: |
   end
 
   obj = Example.new
+  gen = GenExample.new
 benchmark:
-  vm_ivar_get: |
+  vm_ivar_get_on_obj: |
     obj.get_value_loop
+  vm_ivar_get_on_class: |
+    Example.get_value_loop
+  vm_ivar_get_on_generic: |
+    gen.get_value_loop
 loop_count: 100
diff --git a/benchmark/vm_ivar_ic_miss.yml b/benchmark/vm_ivar_ic_miss.yml
new file mode 100644
index 0000000000..944fb1a9e6
--- /dev/null
+++ b/benchmark/vm_ivar_ic_miss.yml
@@ -0,0 +1,20 @@
+prelude: |
+  class Foo
+    def initialize diverge
+      if diverge
+        @a = 1
+      end
+
+      @a0 = @a1 = @a2 = @a3 = @a4 = @a5 = @a6 = @a7 = @a8 = @a9 = @a10 = @a11 = @a12 = @a13 = @a14 = @a15 = @a16 = @a17 = @a18 = @a19 = @a20 = @a21 = @a22 = @a23 = @a24 = @a25 = @a26 = @a27 = @a28 = @a29 = @a30 = @a31 = @a32 = @a33 = @a34 = @a35 = @a36 = @a37 = @a38 = @a39 = @a40 = @a41 = @a42 = @a43 = @a44 = @a45 = @a46 = @a47 = @a48 = @a49 = @a50 = @a51 = @a52 = @a53 = @a54 = @a55 = @a56 = @a57 = @a58 = @a59 = @a60 = @a61 = @a62 = @a63 = @a64 = @a65 = @a66 = @a67 = @a68 = @a69 = @a70 = @a71 = @a72 = @a73 = @a74 = @b = 1
+    end
+
+    def b; @b; end
+  end
+
+  a = Foo.new false
+  b = Foo.new true
+benchmark:
+  vm_ivar_ic_miss: |
+    a.b
+    b.b
+loop_count: 30000000
diff --git a/benchmark/vm_ivar_memoize.yml b/benchmark/vm_ivar_memoize.yml
new file mode 100644
index 0000000000..90f6b07f05
--- /dev/null
+++ b/benchmark/vm_ivar_memoize.yml
@@ -0,0 +1,85 @@
+prelude: |
+  IVARS = 60
+  class Record
+    def initialize(offset = false)
+      @offset = 1 if offset
+      @first = 0
+      IVARS.times do |i|
+        instance_variable_set("@ivar_#{i}", i)
+      end
+    end
+
+    def first
+      @first
+    end
+
+    def lazy_set
+      @lazy_set ||= 123
+    end
+
+    def undef
+      @undef
+    end
+  end
+
+  Record.new # Need one alloc to right size
+
+  BASE = Record.new
+  LAZY = Record.new
+  LAZY.lazy_set
+
+  class Miss < Record
+    @first = 0
+    IVARS.times do |i|
+      instance_variable_set("@i_#{i}", i)
+    end
+  end
+
+  Miss.new # Need one alloc to right size
+  MISS = Miss.new
+
+  DIVERGENT = Record.new(true)
+
+benchmark:
+  vm_ivar_stable_shape: |
+    BASE.first
+    BASE.first
+    BASE.first
+    BASE.first
+    BASE.first
+    BASE.first
+  vm_ivar_memoize_unstable_shape: |
+    BASE.first
+    LAZY.first
+    BASE.first
+    LAZY.first
+    BASE.first
+    LAZY.first
+  vm_ivar_memoize_unstable_shape_miss: |
+    BASE.first
+    MISS.first
+    BASE.first
+    MISS.first
+    BASE.first
+    MISS.first
+  vm_ivar_unstable_undef: |
+    BASE.undef
+    LAZY.undef
+    BASE.undef
+    LAZY.undef
+    BASE.undef
+    LAZY.undef
+  vm_ivar_divergent_shape: |
+    BASE.first
+    DIVERGENT.first
+    BASE.first
+    DIVERGENT.first
+    BASE.first
+    DIVERGENT.first
+  vm_ivar_divergent_shape_imbalanced: |
+    BASE.first
+    DIVERGENT.first
+    DIVERGENT.first
+    DIVERGENT.first
+    DIVERGENT.first
+    DIVERGENT.first
diff --git a/benchmark/vm_ivar_set_on_instance.yml b/benchmark/vm_ivar_set_on_instance.yml
index 91857b7742..6ce53a86ec 100644
--- a/benchmark/vm_ivar_set_on_instance.yml
+++ b/benchmark/vm_ivar_set_on_instance.yml
@@ -1,16 +1,44 @@
 prelude: |
   class TheClass
     def initialize
+      @levar = 1
       @v0 = 1
       @v1 = 2
       @v3 = 3
+    end
+
+    def set_value_loop
+      # 100k
+      i = 0
+      while i < 100_000
+        # 10 times to de-emphasize loop overhead
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        i += 1
+      end
+    end
+  end
+
+  class Generic < Time
+    def initialize
       @levar = 1
+      @v0 = 1
+      @v1 = 2
+      @v3 = 3
     end
 
     def set_value_loop
-      # 1M
+      # 100k
       i = 0
-      while i < 1000000
+      while i < 100_000
         # 10 times to de-emphasize loop overhead
         @levar = i
         @levar = i
@@ -28,8 +56,39 @@ prelude: |
   end
 
   obj = TheClass.new
+  gen_obj = Generic.new
+
+  class SomeClass
+    @levar = 1
+    @v0 = 1
+    @v1 = 2
+    @v3 = 3
+
+    def self.set_value_loop
+      # 100k
+      i = 0
+      while i < 100_000
+        # 10 times to de-emphasize loop overhead
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        @levar = i
+        i += 1
+      end
+    end
+  end
 
 benchmark:
   vm_ivar_set_on_instance: |
     obj.set_value_loop
+  vm_ivar_set_on_generic: |
+    gen_obj.set_value_loop
+  vm_ivar_set_on_class: |
+    SomeClass.set_value_loop
 loop_count: 100
diff --git a/benchmark/vm_lvar_cond_set.yml b/benchmark/vm_lvar_cond_set.yml
new file mode 100644
index 0000000000..1845f9d12e
--- /dev/null
+++ b/benchmark/vm_lvar_cond_set.yml
@@ -0,0 +1,8 @@
+benchmark:
+  vm_lvar_cond_set: |
+    a ||= 1
+    b ||= 1
+    c ||= 1
+    d ||= 1
+    nil
+loop_count: 30000000
diff --git a/benchmark/vm_method_splat_calls.yml b/benchmark/vm_method_splat_calls.yml
new file mode 100644
index 0000000000..f2f366e99c
--- /dev/null
+++ b/benchmark/vm_method_splat_calls.yml
@@ -0,0 +1,13 @@
+prelude: |
+  def f(x=0, y: 0) end
+  a = [1]
+  ea = []
+  kw = {y: 1}
+  b = lambda{}
+benchmark:
+  arg_splat: "f(1, *ea)"
+  arg_splat_block: "f(1, *ea, &b)"
+  splat_kw_splat: "f(*a, **kw)"
+  splat_kw_splat_block: "f(*a, **kw, &b)"
+  splat_kw: "f(*a, y: 1)"
+  splat_kw_block: "f(*a, y: 1, &b)"
diff --git a/benchmark/vm_method_splat_calls2.yml b/benchmark/vm_method_splat_calls2.yml
new file mode 100644
index 0000000000..d33dcd7e8b
--- /dev/null
+++ b/benchmark/vm_method_splat_calls2.yml
@@ -0,0 +1,27 @@
+prelude: |
+  def named_arg_splat(*a) end
+  def named_arg_kw_splat(*a, **kw) end
+  def anon_arg_splat(*) end
+  def anon_kw_splat(**) end
+  def anon_arg_kw_splat(*, **) end
+  def anon_fw_to_named(*, **) named_arg_kw_splat(*, **) end
+  def fw_to_named(...) named_arg_kw_splat(...) end
+  def fw_to_anon_to_named(...) anon_fw_to_named(...) end
+  def fw_no_kw(...) named_arg_splat(...) end
+  a = [1]
+  kw = {y: 1}
+benchmark:
+  named_multi_arg_splat: "named_arg_splat(*a, *a)"
+  named_post_splat: "named_arg_splat(*a, a)"
+  anon_arg_splat: "anon_arg_splat(*a)"
+  anon_arg_kw_splat: "anon_arg_kw_splat(*a, **kw)"
+  anon_multi_arg_splat: "anon_arg_splat(*a, *a)"
+  anon_post_splat: "anon_arg_splat(*a, a)"
+  anon_kw_splat: "anon_kw_splat(**kw)"
+  anon_fw_to_named_splat: "anon_fw_to_named(*a, **kw)"
+  anon_fw_to_named_no_splat: "anon_fw_to_named(1, y: 1)"
+  fw_to_named_splat: "fw_to_named(*a, **kw)"
+  fw_to_named_no_splat: "fw_to_named(1, y: 1)"
+  fw_to_anon_to_named_splat: "fw_to_anon_to_named(*a, **kw)"
+  fw_to_anon_to_named_no_splat: "fw_to_anon_to_named(1, y: 1)"
+  fw_no_kw: "fw_no_kw(1, 2)"
diff --git a/benchmark/vm_send_cfunc.yml b/benchmark/vm_send_cfunc.yml
index b114ac317d..6f12b65176 100644
--- a/benchmark/vm_send_cfunc.yml
+++ b/benchmark/vm_send_cfunc.yml
@@ -1,3 +1,14 @@
+prelude: |
+  ary = []
+  kw = {a: 1}
+  empty_kw = {}
+  kw_ary = [Hash.ruby2_keywords_hash(a: 1)]
+  empty_kw_ary = [Hash.ruby2_keywords_hash({})]
 benchmark:
-  vm_send_cfunc: self.class
-loop_count: 100000000
+  vm_send_cfunc: itself
+  vm_send_cfunc_splat: itself(*ary)
+  vm_send_cfunc_splat_kw_hash: equal?(*kw_ary)
+  vm_send_cfunc_splat_empty_kw_hash: itself(*empty_kw_ary)
+  vm_send_cfunc_splat_kw: equal?(*ary, **kw)
+  vm_send_cfunc_splat_empty_kw: itself(*ary, **empty_kw)
+loop_count: 20000000
diff --git a/benchmark/vm_super_splat_calls.yml b/benchmark/vm_super_splat_calls.yml
new file mode 100644
index 0000000000..795e44e4da
--- /dev/null
+++ b/benchmark/vm_super_splat_calls.yml
@@ -0,0 +1,25 @@
+prelude: |
+  @a = [1].freeze
+  @ea = [].freeze
+  @kw = {y: 1}.freeze
+  @b = lambda{}
+  extend(Module.new{def arg_splat(x=0, y: 0) end})
+  extend(Module.new{def arg_splat_block(x=0, y: 0) end})
+  extend(Module.new{def splat_kw_splat(x=0, y: 0) end})
+  extend(Module.new{def splat_kw_splat_block(x=0, y: 0) end})
+  extend(Module.new{def splat_kw(x=0, y: 0) end})
+  extend(Module.new{def splat_kw_block(x=0, y: 0) end})
+
+  extend(Module.new{def arg_splat; super(1, *@ea) end})
+  extend(Module.new{def arg_splat_block; super(1, *@ea, &@b) end})
+  extend(Module.new{def splat_kw_splat; super(*@a, **@kw) end})
+  extend(Module.new{def splat_kw_splat_block; super(*@a, **@kw, &@b) end})
+  extend(Module.new{def splat_kw; super(*@a, y: 1) end})
+  extend(Module.new{def splat_kw_block; super(*@a, y: 1, &@b) end})
+benchmark:
+  arg_splat: "arg_splat"
+  arg_splat_block: "arg_splat_block"
+  splat_kw_splat: "splat_kw_splat"
+  splat_kw_splat_block: "splat_kw_splat_block"
+  splat_kw: "splat_kw"
+  splat_kw_block: "splat_kw_block"
diff --git a/benchmark/vm_zsuper_splat_calls.yml b/benchmark/vm_zsuper_splat_calls.yml
new file mode 100644
index 0000000000..82dc22349d
--- /dev/null
+++ b/benchmark/vm_zsuper_splat_calls.yml
@@ -0,0 +1,28 @@
+prelude: |
+  a = [1].freeze
+  ea = [].freeze
+  kw = {y: 1}.freeze
+  b = lambda{}
+  extend(Module.new{def arg_splat(x=0, y: 0) end})
+  extend(Module.new{def arg_splat_block(x=0, y: 0) end})
+  extend(Module.new{def arg_splat_post(x=0, y: 0) end})
+  extend(Module.new{def splat_kw_splat(x=0, y: 0) end})
+  extend(Module.new{def splat_kw_splat_block(x=0, y: 0) end})
+  extend(Module.new{def splat_kw(x=0, y: 0) end})
+  extend(Module.new{def splat_kw_block(x=0, y: 0) end})
+
+  extend(Module.new{def arg_splat(x, *a) super end})
+  extend(Module.new{def arg_splat_block(x, *a, &b) super end})
+  extend(Module.new{def arg_splat_post(*a, x) super end})
+  extend(Module.new{def splat_kw_splat(*a, **kw) super end})
+  extend(Module.new{def splat_kw_splat_block(*a, **kw, &b) super end})
+  extend(Module.new{def splat_kw(*a, y: 1) super end})
+  extend(Module.new{def splat_kw_block(*a, y: 1, &b) super end})
+benchmark:
+  arg_splat: "arg_splat(1, *ea)"
+  arg_splat_block: "arg_splat_block(1, *ea, &b)"
+  arg_splat_post: "arg_splat_post(1, *ea, &b)"
+  splat_kw_splat: "splat_kw_splat(*a, **kw)"
+  splat_kw_splat_block: "splat_kw_splat_block(*a, **kw, &b)"
+  splat_kw: "splat_kw(*a, y: 1)"
+  splat_kw_block: "splat_kw_block(*a, y: 1, &b)"
diff --git a/bignum.c b/bignum.c
index 9901a807b1..ee2fa1ed30 100644
--- a/bignum.c
+++ b/bignum.c
@@ -30,9 +30,6 @@
 # define USE_GMP 0
 #endif
 #endif
-#if USE_GMP
-# include <gmp.h>
-#endif
 
 #include "id.h"
 #include "internal.h"
@@ -48,6 +45,23 @@
 #include "ruby/util.h"
 #include "ruby_assert.h"
 
+#if USE_GMP
+RBIMPL_WARNING_PUSH()
+# ifdef _MSC_VER
+RBIMPL_WARNING_IGNORED(4146) /* for mpn_neg() */
+# endif
+# include <gmp.h>
+RBIMPL_WARNING_POP()
+#endif
+
+static const bool debug_integer_pack = (
+#ifdef DEBUG_INTEGER_PACK
+    DEBUG_INTEGER_PACK+0
+#else
+    RUBY_DEBUG
+#endif
+    ) != 0;
+
 const char ruby_digitmap[] = "0123456789abcdefghijklmnopqrstuvwxyz";
 
 #ifndef SIZEOF_BDIGIT_DBL
@@ -65,7 +79,6 @@ STATIC_ASSERT(sizeof_bdigit_and_dbl, SIZEOF_BDIGIT*2 <= SIZEOF_BDIGIT_DBL);
 STATIC_ASSERT(bdigit_signedness, 0 < (BDIGIT)-1);
 STATIC_ASSERT(bdigit_dbl_signedness, 0 < (BDIGIT_DBL)-1);
 STATIC_ASSERT(bdigit_dbl_signed_signedness, 0 > (BDIGIT_DBL_SIGNED)-1);
-STATIC_ASSERT(rbignum_embed_len_max, BIGNUM_EMBED_LEN_MAX <= (BIGNUM_EMBED_LEN_MASK >> BIGNUM_EMBED_LEN_SHIFT));
 
 #if SIZEOF_BDIGIT < SIZEOF_LONG
 STATIC_ASSERT(sizeof_long_and_sizeof_bdigit, SIZEOF_LONG % SIZEOF_BDIGIT == 0);
@@ -341,7 +354,7 @@ maxpow_in_bdigit_dbl(int base, int *exp_ret)
     BDIGIT_DBL maxpow;
     int exponent;
 
-    assert(2 <= base && base <= 36);
+    RUBY_ASSERT(2 <= base && base <= 36);
 
     {
 #if SIZEOF_BDIGIT_DBL == 2
@@ -373,7 +386,7 @@ maxpow_in_bdigit_dbl(int base, int *exp_ret)
 static inline BDIGIT_DBL
 bary2bdigitdbl(const BDIGIT *ds, size_t n)
 {
-    assert(n <= 2);
+    RUBY_ASSERT(n <= 2);
 
     if (n == 2)
         return ds[0] | BIGUP(ds[1]);
@@ -385,7 +398,7 @@ bary2bdigitdbl(const BDIGIT *ds, size_t n)
 static inline void
 bdigitdbl2bary(BDIGIT *ds, size_t n, BDIGIT_DBL num)
 {
-    assert(n == 2);
+    RUBY_ASSERT(n == 2);
 
     ds[0] = BIGLO(num);
     ds[1] = (BDIGIT)BIGDN(num);
@@ -416,7 +429,7 @@ bary_small_lshift(BDIGIT *zds, const BDIGIT *xds, size_t n, int shift)
 {
     size_t i;
     BDIGIT_DBL num = 0;
-    assert(0 <= shift && shift < BITSPERDIG);
+    RUBY_ASSERT(0 <= shift && shift < BITSPERDIG);
 
     for (i=0; i<n; i++) {
         num = num | (BDIGIT_DBL)*xds++ << shift;
@@ -432,7 +445,7 @@ bary_small_rshift(BDIGIT *zds, const BDIGIT *xds, size_t n, int shift, BDIGIT hi
     size_t i;
     BDIGIT_DBL num = 0;
 
-    assert(0 <= shift && shift < BITSPERDIG);
+    RUBY_ASSERT(0 <= shift && shift < BITSPERDIG);
 
     num = BIGUP(higher_bdigit);
     for (i = 0; i < n; i++) {
@@ -977,7 +990,7 @@ integer_unpack_num_bdigits_small(size_t numwords, size_t wordsize, size_t nails,
 {
     /* nlp_bits stands for number of leading padding bits */
     size_t num_bits = (wordsize * CHAR_BIT - nails) * numwords;
-    size_t num_bdigits = (num_bits + BITSPERDIG - 1) / BITSPERDIG;
+    size_t num_bdigits = roomof(num_bits, BITSPERDIG);
     *nlp_bits_ret = (int)(num_bdigits * BITSPERDIG - num_bits);
     return num_bdigits;
 }
@@ -987,7 +1000,7 @@ integer_unpack_num_bdigits_generic(size_t numwords, size_t wordsize, size_t nail
 {
     /* BITSPERDIG = SIZEOF_BDIGIT * CHAR_BIT */
     /* num_bits = (wordsize * CHAR_BIT - nails) * numwords */
-    /* num_bdigits = (num_bits + BITSPERDIG - 1) / BITSPERDIG */
+    /* num_bdigits = roomof(num_bits, BITSPERDIG) */
 
     /* num_bits = CHAR_BIT * (wordsize * numwords) - nails * numwords = CHAR_BIT * num_bytes1 - nails * numwords */
     size_t num_bytes1 = wordsize * numwords;
@@ -1049,15 +1062,13 @@ integer_unpack_num_bdigits(size_t numwords, size_t wordsize, size_t nails, int *
 
     if (numwords <= (SIZE_MAX - (BITSPERDIG-1)) / CHAR_BIT / wordsize) {
         num_bdigits = integer_unpack_num_bdigits_small(numwords, wordsize, nails, nlp_bits_ret);
-#ifdef DEBUG_INTEGER_PACK
-        {
+        if (debug_integer_pack) {
             int nlp_bits1;
             size_t num_bdigits1 = integer_unpack_num_bdigits_generic(numwords, wordsize, nails, &nlp_bits1);
-            assert(num_bdigits == num_bdigits1);
-            assert(*nlp_bits_ret == nlp_bits1);
+            RUBY_ASSERT(num_bdigits == num_bdigits1);
+            RUBY_ASSERT(*nlp_bits_ret == nlp_bits1);
             (void)num_bdigits1;
         }
-#endif
     }
     else {
         num_bdigits = integer_unpack_num_bdigits_generic(numwords, wordsize, nails, nlp_bits_ret);
@@ -1265,7 +1276,7 @@ bary_unpack_internal(BDIGIT *bdigits, size_t num_bdigits, const void *words, siz
         }
         if (dd)
             *dp++ = (BDIGIT)dd;
-        assert(dp <= de);
+        RUBY_ASSERT(dp <= de);
         while (dp < de)
             *dp++ = 0;
 #undef PUSH_BITS
@@ -1324,7 +1335,7 @@ bary_unpack(BDIGIT *bdigits, size_t num_bdigits, const void *words, size_t numwo
 
     num_bdigits0 = integer_unpack_num_bdigits(numwords, wordsize, nails, &nlp_bits);
 
-    assert(num_bdigits0 <= num_bdigits);
+    RUBY_ASSERT(num_bdigits0 <= num_bdigits);
 
     sign = bary_unpack_internal(bdigits, num_bdigits0, words, numwords, wordsize, nails, flags, nlp_bits);
 
@@ -1343,8 +1354,8 @@ bary_subb(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yd
     size_t i;
     size_t sn;
 
-    assert(xn <= zn);
-    assert(yn <= zn);
+    RUBY_ASSERT(xn <= zn);
+    RUBY_ASSERT(yn <= zn);
 
     sn = xn < yn ? xn : yn;
 
@@ -1405,8 +1416,8 @@ bary_addc(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yd
     BDIGIT_DBL num;
     size_t i;
 
-    assert(xn <= zn);
-    assert(yn <= zn);
+    RUBY_ASSERT(xn <= zn);
+    RUBY_ASSERT(yn <= zn);
 
     if (xn > yn) {
         const BDIGIT *tds;
@@ -1470,7 +1481,7 @@ bary_mul_single(BDIGIT *zds, size_t zn, BDIGIT x, BDIGIT y)
 {
     BDIGIT_DBL n;
 
-    assert(2 <= zn);
+    RUBY_ASSERT(2 <= zn);
 
     n = (BDIGIT_DBL)x * y;
     bdigitdbl2bary(zds, 2, n);
@@ -1484,7 +1495,7 @@ bary_muladd_1xN(BDIGIT *zds, size_t zn, BDIGIT x, const BDIGIT *yds, size_t yn)
     BDIGIT_DBL dd;
     size_t j;
 
-    assert(zn > yn);
+    RUBY_ASSERT(zn > yn);
 
     if (x == 0)
         return 0;
@@ -1519,7 +1530,7 @@ bigdivrem_mulsub(BDIGIT *zds, size_t zn, BDIGIT x, const BDIGIT *yds, size_t yn)
     BDIGIT_DBL t2;
     BDIGIT_DBL_SIGNED num;
 
-    assert(zn == yn + 1);
+    RUBY_ASSERT(zn == yn + 1);
 
     num = 0;
     t2 = 0;
@@ -1544,7 +1555,7 @@ bary_mulsub_1xN(BDIGIT *zds, size_t zn, BDIGIT x, const BDIGIT *yds, size_t yn)
 {
     BDIGIT_DBL_SIGNED num;
 
-    assert(zn == yn + 1);
+    RUBY_ASSERT(zn == yn + 1);
 
     num = bigdivrem_mulsub(zds, zn, x, yds, yn);
     zds[yn] = BIGLO(num);
@@ -1558,7 +1569,7 @@ bary_mul_normal(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIG
 {
     size_t i;
 
-    assert(xn + yn <= zn);
+    RUBY_ASSERT(xn + yn <= zn);
 
     BDIGITS_ZERO(zds, zn);
     for (i = 0; i < xn; i++) {
@@ -1589,7 +1600,7 @@ bary_sq_fast(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn)
     BDIGIT vl;
     int vh;
 
-    assert(xn * 2 <= zn);
+    RUBY_ASSERT(xn * 2 <= zn);
 
     BDIGITS_ZERO(zds, zn);
 
@@ -1661,9 +1672,9 @@ bary_mul_balance_with_mulfunc(BDIGIT *const zds, const size_t zn,
     VALUE work = 0;
     size_t n;
 
-    assert(xn + yn <= zn);
-    assert(xn <= yn);
-    assert(!KARATSUBA_BALANCED(xn, yn) || !TOOM3_BALANCED(xn, yn));
+    RUBY_ASSERT(xn + yn <= zn);
+    RUBY_ASSERT(xn <= yn);
+    RUBY_ASSERT(!KARATSUBA_BALANCED(xn, yn) || !TOOM3_BALANCED(xn, yn));
 
     BDIGITS_ZERO(zds, xn);
 
@@ -1745,9 +1756,9 @@ bary_mul_karatsuba(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const B
     const BDIGIT *xds0, *xds1, *yds0, *yds1;
     BDIGIT *zds0, *zds1, *zds2, *zds3;
 
-    assert(xn + yn <= zn);
-    assert(xn <= yn);
-    assert(yn < 2 * xn);
+    RUBY_ASSERT(xn + yn <= zn);
+    RUBY_ASSERT(xn <= yn);
+    RUBY_ASSERT(yn < 2 * xn);
 
     sq = xds == yds && xn == yn;
 
@@ -1762,7 +1773,7 @@ bary_mul_karatsuba(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const B
 
     n = yn / 2;
 
-    assert(n < xn);
+    RUBY_ASSERT(n < xn);
 
     if (wn < n) {
         /* This function itself needs only n BDIGITs for work area.
@@ -1883,7 +1894,7 @@ bary_mul_karatsuba(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const B
         for (x = 0, i = xn-1; 0 <= i; i--) { x <<= SIZEOF_BDIGIT*CHAR_BIT; x |= xds[i]; }
         for (y = 0, i = yn-1; 0 <= i; i--) { y <<= SIZEOF_BDIGIT*CHAR_BIT; y |= yds[i]; }
         for (z = 0, i = zn-1; 0 <= i; i--) { z <<= SIZEOF_BDIGIT*CHAR_BIT; z |= zds[i]; }
-        assert(z == x * y);
+        RUBY_ASSERT(z == x * y);
     }
     */
 
@@ -1951,11 +1962,11 @@ bary_mul_toom3(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGI
 
     int sq = xds == yds && xn == yn;
 
-    assert(xn <= yn);  /* assume y >= x */
-    assert(xn + yn <= zn);
+    RUBY_ASSERT(xn <= yn);  /* assume y >= x */
+    RUBY_ASSERT(xn + yn <= zn);
 
     n = (yn + 2) / 3;
-    assert(2*n < xn);
+    RUBY_ASSERT(2*n < xn);
 
     wnc = 0;
 
@@ -2142,19 +2153,19 @@ bary_mul_toom3(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGI
     /* z(1) : t1 <- u1 * v1 */
     bary_mul_toom3_start(t1ds, t1n, u1ds, u1n, v1ds, v1n, wds, wn);
     t1p = u1p == v1p;
-    assert(t1ds[t1n-1] == 0);
+    RUBY_ASSERT(t1ds[t1n-1] == 0);
     t1n--;
 
     /* z(-1) : t2 <- u2 * v2 */
     bary_mul_toom3_start(t2ds, t2n, u2ds, u2n, v2ds, v2n, wds, wn);
     t2p = u2p == v2p;
-    assert(t2ds[t2n-1] == 0);
+    RUBY_ASSERT(t2ds[t2n-1] == 0);
     t2n--;
 
     /* z(-2) : t3 <- u3 * v3 */
     bary_mul_toom3_start(t3ds, t3n, u3ds, u3n, v3ds, v3n, wds, wn);
     t3p = u3p == v3p;
-    assert(t3ds[t3n-1] == 0);
+    RUBY_ASSERT(t3ds[t3n-1] == 0);
     t3n--;
 
     /* z(inf) : t4 <- x2 * y2 */
@@ -2330,7 +2341,7 @@ bary_mul_gmp(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT
     mpz_t x, y, z;
     size_t count;
 
-    assert(xn + yn <= zn);
+    RUBY_ASSERT(xn + yn <= zn);
 
     mpz_init(x);
     mpz_init(y);
@@ -2365,7 +2376,7 @@ rb_big_mul_gmp(VALUE x, VALUE y)
 static void
 bary_short_mul(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yds, size_t yn)
 {
-    assert(xn + yn <= zn);
+    RUBY_ASSERT(xn + yn <= zn);
 
     if (xn == 1 && yn == 1) {
         bary_mul_single(zds, zn, xds[0], yds[0]);
@@ -2401,7 +2412,7 @@ bary_mul_precheck(BDIGIT **zdsp, size_t *znp, const BDIGIT **xdsp, size_t *xnp,
     const BDIGIT *yds = *ydsp;
     size_t yn = *ynp;
 
-    assert(xn + yn <= zn);
+    RUBY_ASSERT(xn + yn <= zn);
 
     nlsz = 0;
 
@@ -2450,7 +2461,7 @@ bary_mul_precheck(BDIGIT **zdsp, size_t *znp, const BDIGIT **xdsp, size_t *xnp,
         tds = xds; xds = yds; yds = tds;
         tn = xn; xn = yn; yn = tn;
     }
-    assert(xn <= yn);
+    RUBY_ASSERT(xn <= yn);
 
     if (xn <= 1) {
         if (xn == 0) {
@@ -2633,8 +2644,8 @@ rb_big_stop(void *ptr)
 static BDIGIT
 bigdivrem_single1(BDIGIT *qds, const BDIGIT *xds, size_t xn, BDIGIT x_higher_bdigit, BDIGIT y)
 {
-    assert(0 < xn);
-    assert(x_higher_bdigit < y);
+    RUBY_ASSERT(0 < xn);
+    RUBY_ASSERT(x_higher_bdigit < y);
     if (POW2_P(y)) {
         BDIGIT r;
         r = xds[0] & (y-1);
@@ -2666,9 +2677,9 @@ bigdivrem_restoring(BDIGIT *zds, size_t zn, BDIGIT *yds, size_t yn)
     struct big_div_struct bds;
     size_t ynzero;
 
-    assert(yn < zn);
-    assert(BDIGIT_MSB(yds[yn-1]));
-    assert(zds[zn-1] < yds[yn-1]);
+    RUBY_ASSERT(yn < zn);
+    RUBY_ASSERT(BDIGIT_MSB(yds[yn-1]));
+    RUBY_ASSERT(zds[zn-1] < yds[yn-1]);
 
     for (ynzero = 0; !yds[ynzero]; ynzero++);
 
@@ -2687,7 +2698,7 @@ bigdivrem_restoring(BDIGIT *zds, size_t zn, BDIGIT *yds, size_t yn)
     if (bds.zn > 10000 || bds.yn > 10000) {
       retry:
         bds.stop = Qfalse;
-        rb_nogvl(bigdivrem1, &bds, rb_big_stop, &bds, RB_NOGVL_UBF_ASYNC_SAFE);
+        rb_nogvl(bigdivrem1, &bds, rb_big_stop, &bds, RB_NOGVL_UBF_ASYNC_SAFE | RB_NOGVL_OFFLOAD_SAFE);
 
         if (bds.stop == Qtrue) {
             /* execute trap handler, but exception was not raised. */
@@ -2707,9 +2718,9 @@ bary_divmod_normal(BDIGIT *qds, size_t qn, BDIGIT *rds, size_t rn, const BDIGIT
     size_t zn;
     VALUE tmpyz = 0;
 
-    assert(yn < xn || (xn == yn && yds[yn - 1] <= xds[xn - 1]));
-    assert(qds ? (xn - yn + 1) <= qn : 1);
-    assert(rds ? yn <= rn : 1);
+    RUBY_ASSERT(yn < xn || (xn == yn && yds[yn - 1] <= xds[xn - 1]));
+    RUBY_ASSERT(qds ? (xn - yn + 1) <= qn : 1);
+    RUBY_ASSERT(rds ? yn <= rn : 1);
 
     zn = xn + BIGDIVREM_EXTRA_WORDS;
 
@@ -2801,10 +2812,10 @@ bary_divmod_gmp(BDIGIT *qds, size_t qn, BDIGIT *rds, size_t rn, const BDIGIT *xd
     mpz_t x, y, q, r;
     size_t count;
 
-    assert(yn < xn || (xn == yn && yds[yn - 1] <= xds[xn - 1]));
-    assert(qds ? (xn - yn + 1) <= qn : 1);
-    assert(rds ? yn <= rn : 1);
-    assert(qds || rds);
+    RUBY_ASSERT(yn < xn || (xn == yn && yds[yn - 1] <= xds[xn - 1]));
+    RUBY_ASSERT(qds ? (xn - yn + 1) <= qn : 1);
+    RUBY_ASSERT(rds ? yn <= rn : 1);
+    RUBY_ASSERT(qds || rds);
 
     mpz_init(x);
     mpz_init(y);
@@ -2890,8 +2901,8 @@ bary_divmod_branch(BDIGIT *qds, size_t qn, BDIGIT *rds, size_t rn, const BDIGIT
 static void
 bary_divmod(BDIGIT *qds, size_t qn, BDIGIT *rds, size_t rn, const BDIGIT *xds, size_t xn, const BDIGIT *yds, size_t yn)
 {
-    assert(xn <= qn);
-    assert(yn <= rn);
+    RUBY_ASSERT(xn <= qn);
+    RUBY_ASSERT(yn <= rn);
 
     BARY_TRUNC(yds, yn);
     if (yn == 0)
@@ -2978,25 +2989,56 @@ rb_cmpint(VALUE val, VALUE a, VALUE b)
             ((l) << BIGNUM_EMBED_LEN_SHIFT)) : \
      (void)(RBIGNUM(b)->as.heap.len = (l)))
 
+static size_t
+big_embed_capa(VALUE big)
+{
+    size_t size = rb_gc_obj_slot_size(big) - offsetof(struct RBignum, as.ary);
+    RUBY_ASSERT(size % sizeof(BDIGIT) == 0);
+    size_t capa = size / sizeof(BDIGIT);
+    RUBY_ASSERT(capa <= BIGNUM_EMBED_LEN_MAX);
+    return capa;
+}
+
+static size_t
+big_embed_size(size_t capa)
+{
+    size_t size = offsetof(struct RBignum, as.ary) + (sizeof(BDIGIT) * capa);
+    if (size < sizeof(struct RBignum)) {
+        size = sizeof(struct RBignum);
+    }
+    return size;
+}
+
+static bool
+big_embeddable_p(size_t capa)
+{
+    if (capa > BIGNUM_EMBED_LEN_MAX) {
+        return false;
+    }
+    return rb_gc_size_allocatable_p(big_embed_size(capa));
+}
+
 static void
 rb_big_realloc(VALUE big, size_t len)
 {
     BDIGIT *ds;
+    size_t embed_capa = big_embed_capa(big);
+
     if (BIGNUM_EMBED_P(big)) {
-        if (BIGNUM_EMBED_LEN_MAX < len) {
+        if (embed_capa < len) {
             ds = ALLOC_N(BDIGIT, len);
-            MEMCPY(ds, RBIGNUM(big)->as.ary, BDIGIT, BIGNUM_EMBED_LEN_MAX);
+            MEMCPY(ds, RBIGNUM(big)->as.ary, BDIGIT, embed_capa);
             RBIGNUM(big)->as.heap.len = BIGNUM_LEN(big);
             RBIGNUM(big)->as.heap.digits = ds;
             FL_UNSET_RAW(big, BIGNUM_EMBED_FLAG);
         }
     }
     else {
-        if (len <= BIGNUM_EMBED_LEN_MAX) {
+        if (len <= embed_capa) {
             ds = RBIGNUM(big)->as.heap.digits;
             FL_SET_RAW(big, BIGNUM_EMBED_FLAG);
             BIGNUM_SET_LEN(big, len);
-            (void)VALGRIND_MAKE_MEM_UNDEFINED((void*)RBIGNUM(big)->as.ary, sizeof(RBIGNUM(big)->as.ary));
+            (void)VALGRIND_MAKE_MEM_UNDEFINED((void*)RBIGNUM(big)->as.ary, embed_capa * sizeof(BDIGIT));
             if (ds) {
                 MEMCPY(RBIGNUM(big)->as.ary, ds, BDIGIT, len);
                 xfree(ds);
@@ -3006,7 +3048,7 @@ rb_big_realloc(VALUE big, size_t len)
             if (BIGNUM_LEN(big) == 0) {
                 RBIGNUM(big)->as.heap.digits = ALLOC_N(BDIGIT, len);
             }
-            else {
+            else if (BIGNUM_LEN(big) < len) {
                 REALLOC_N(RBIGNUM(big)->as.heap.digits, BDIGIT, len);
             }
         }
@@ -3023,15 +3065,24 @@ rb_big_resize(VALUE big, size_t len)
 static VALUE
 bignew_1(VALUE klass, size_t len, int sign)
 {
-    NEWOBJ_OF(big, struct RBignum, klass, T_BIGNUM | (RGENGC_WB_PROTECTED_BIGNUM ? FL_WB_PROTECTED : 0));
-    VALUE bigv = (VALUE)big;
-    BIGNUM_SET_SIGN(bigv, sign);
-    if (len <= BIGNUM_EMBED_LEN_MAX) {
-        FL_SET_RAW(bigv, BIGNUM_EMBED_FLAG);
+    VALUE bigv;
+
+    if (big_embeddable_p(len)) {
+        size_t size = big_embed_size(len);
+        RUBY_ASSERT(rb_gc_size_allocatable_p(size));
+        NEWOBJ_OF(big, struct RBignum, klass,
+                T_BIGNUM | BIGNUM_EMBED_FLAG | (RGENGC_WB_PROTECTED_BIGNUM ? FL_WB_PROTECTED : 0),
+                size, 0);
+        bigv = (VALUE)big;
+        BIGNUM_SET_SIGN(bigv, sign);
         BIGNUM_SET_LEN(bigv, len);
-        (void)VALGRIND_MAKE_MEM_UNDEFINED((void*)big->as.ary, sizeof(big->as.ary));
+        (void)VALGRIND_MAKE_MEM_UNDEFINED((void*)big->as.ary, len * sizeof(BDIGIT));
     }
     else {
+        NEWOBJ_OF(big, struct RBignum, klass,
+                T_BIGNUM | (RGENGC_WB_PROTECTED_BIGNUM ? FL_WB_PROTECTED : 0), sizeof(struct RBignum), 0);
+        bigv = (VALUE)big;
+        BIGNUM_SET_SIGN(bigv, sign);
         big->as.heap.digits = ALLOC_N(BDIGIT, len);
         big->as.heap.len = len;
     }
@@ -3042,7 +3093,9 @@ bignew_1(VALUE klass, size_t len, int sign)
 VALUE
 rb_big_new(size_t len, int sign)
 {
-    return bignew(len, sign != 0);
+    VALUE obj = bignew(len, sign != 0);
+    memset(BIGNUM_DIGITS(obj), 0, len * sizeof(BDIGIT));
+    return obj;
 }
 
 VALUE
@@ -3422,15 +3475,13 @@ rb_absint_numwords(VALUE val, size_t word_numbits, size_t *nlz_bits_ret)
 
     if (numbytes <= SIZE_MAX / CHAR_BIT) {
         numwords = absint_numwords_small(numbytes, nlz_bits_in_msbyte, word_numbits, &nlz_bits);
-#ifdef DEBUG_INTEGER_PACK
-        {
+        if (debug_integer_pack) {
             size_t numwords0, nlz_bits0;
             numwords0 = absint_numwords_generic(numbytes, nlz_bits_in_msbyte, word_numbits, &nlz_bits0);
-            assert(numwords0 == numwords);
-            assert(nlz_bits0 == nlz_bits);
+            RUBY_ASSERT(numwords0 == numwords);
+            RUBY_ASSERT(nlz_bits0 == nlz_bits);
             (void)numwords0;
         }
-#endif
     }
     else {
         numwords = absint_numwords_generic(numbytes, nlz_bits_in_msbyte, word_numbits, &nlz_bits);
@@ -3843,7 +3894,7 @@ str2big_poweroftwo(
     if (numbits) {
         *dp++ = BIGLO(dd);
     }
-    assert((size_t)(dp - BDIGITS(z)) == num_bdigits);
+    RUBY_ASSERT((size_t)(dp - BDIGITS(z)) == num_bdigits);
 
     return z;
 }
@@ -3886,7 +3937,7 @@ str2big_normal(
             }
             break;
         }
-        assert(blen <= num_bdigits);
+        RUBY_ASSERT(blen <= num_bdigits);
     }
 
     return z;
@@ -3944,7 +3995,7 @@ str2big_karatsuba(
             current_base = 1;
         }
     }
-    assert(i == num_bdigits);
+    RUBY_ASSERT(i == num_bdigits);
     for (unit = 2; unit < num_bdigits; unit *= 2) {
         for (i = 0; i < num_bdigits; i += unit*2) {
             if (2*unit <= num_bdigits - i) {
@@ -4089,8 +4140,8 @@ rb_int_parse_cstr(const char *str, ssize_t len, char **endp, size_t *ndigits,
         len -= (n); \
     } while (0)
 #define ASSERT_LEN() do {\
-        assert(len != 0); \
-        if (len0 >= 0) assert(s + len0 == str + len); \
+        RUBY_ASSERT(len != 0); \
+        if (len0 >= 0) RUBY_ASSERT(s + len0 == str + len); \
     } while (0)
 
     if (!str) {
@@ -4184,7 +4235,6 @@ rb_int_parse_cstr(const char *str, ssize_t len, char **endp, size_t *ndigits,
         }
         if (!c || ISSPACE(c)) --str;
         if (end) len = end - str;
-        ASSERT_LEN();
     }
     c = *str;
     c = conv_digit(c);
@@ -4465,7 +4515,7 @@ rb_str2big_gmp(VALUE arg, int base, int badcheck)
 
 #if HAVE_LONG_LONG
 
-static VALUE
+VALUE
 rb_ull2big(unsigned LONG_LONG n)
 {
     long i;
@@ -4487,7 +4537,7 @@ rb_ull2big(unsigned LONG_LONG n)
     return big;
 }
 
-static VALUE
+VALUE
 rb_ll2big(LONG_LONG n)
 {
     long neg = 0;
@@ -4525,7 +4575,7 @@ rb_ll2inum(LONG_LONG n)
 #endif  /* HAVE_LONG_LONG */
 
 #ifdef HAVE_INT128_T
-static VALUE
+VALUE
 rb_uint128t2big(uint128_t n)
 {
     long i;
@@ -4542,7 +4592,7 @@ rb_uint128t2big(uint128_t n)
     return big;
 }
 
-MJIT_FUNC_EXPORTED VALUE
+VALUE
 rb_int128t2big(int128_t n)
 {
     int neg = 0;
@@ -4587,11 +4637,14 @@ big_shift3(VALUE x, int lshift_p, size_t shift_numdigits, int shift_numbits)
 
     if (lshift_p) {
         if (LONG_MAX < shift_numdigits) {
-            rb_raise(rb_eArgError, "too big number");
+          too_big:
+            rb_raise(rb_eRangeError, "shift width too big");
         }
         s1 = shift_numdigits;
         s2 = shift_numbits;
+        if ((size_t)s1 != shift_numdigits) goto too_big;
         xn = BIGNUM_LEN(x);
+        if (LONG_MAX/SIZEOF_BDIGIT <= xn+s1) goto too_big;
         z = bignew(xn+s1+1, BIGNUM_SIGN(x));
         zds = BDIGITS(z);
         BDIGITS_ZERO(zds, s1);
@@ -4633,8 +4686,8 @@ big_shift2(VALUE x, int lshift_p, VALUE y)
     size_t shift_numdigits;
     int shift_numbits;
 
-    assert(POW2_P(CHAR_BIT));
-    assert(POW2_P(BITSPERDIG));
+    RUBY_ASSERT(POW2_P(CHAR_BIT));
+    RUBY_ASSERT(POW2_P(BITSPERDIG));
 
     if (BIGZEROP(x))
         return INT2FIX(0);
@@ -4721,7 +4774,7 @@ power_cache_get_power(int base, int power_level, size_t *numdigits_ret)
         rb_obj_hide(power);
         base36_power_cache[base - 2][power_level] = power;
         base36_numdigits_cache[base - 2][power_level] = numdigits;
-        rb_gc_register_mark_object(power);
+        rb_vm_register_global_object(power);
     }
     if (numdigits_ret)
         *numdigits_ret = base36_numdigits_cache[base - 2][power_level];
@@ -4757,7 +4810,7 @@ big2str_2bdigits(struct big2str_struct *b2s, BDIGIT *xds, size_t xn, size_t tail
     int beginning = !b2s->ptr;
     size_t len = 0;
 
-    assert(xn <= 2);
+    RUBY_ASSERT(xn <= 2);
     num = bary2bdigitdbl(xds, xn);
 
     if (beginning) {
@@ -4885,7 +4938,7 @@ big2str_karatsuba(struct big2str_struct *b2s, BDIGIT *xds, size_t xn, size_t wn,
             /* bigdivrem_restoring will modify y.
              * So use temporary buffer.  */
             tds = xds + qn;
-            assert(qn + bn <= xn + wn);
+            RUBY_ASSERT(qn + bn <= xn + wn);
             bary_small_lshift(tds, bds, bn, shift);
             xds[xn] = bary_small_lshift(xds, xds, xn, shift);
         }
@@ -4903,7 +4956,7 @@ big2str_karatsuba(struct big2str_struct *b2s, BDIGIT *xds, size_t xn, size_t wn,
         }
 
         BARY_TRUNC(qds, qn);
-        assert(qn <= bn);
+        RUBY_ASSERT(qn <= bn);
         big2str_karatsuba(b2s, qds, qn, xn+wn - (rn+qn), lower_power_level, lower_numdigits+taillen);
         BARY_TRUNC(rds, rn);
         big2str_karatsuba(b2s, rds, rn, xn+wn - rn, lower_power_level, taillen);
@@ -4968,7 +5021,7 @@ big2str_generic(VALUE x, int base)
         invalid_radix(base);
 
     if (xn >= LONG_MAX/BITSPERDIG) {
-        rb_raise(rb_eRangeError, "bignum too big to convert into `string'");
+        rb_raise(rb_eRangeError, "bignum too big to convert into 'string'");
     }
 
     power_level = 0;
@@ -4978,7 +5031,7 @@ big2str_generic(VALUE x, int base)
         power_level++;
         power = power_cache_get_power(base, power_level, NULL);
     }
-    assert(power_level != MAX_BASE36_POWER_TABLE_ENTRIES);
+    RUBY_ASSERT(power_level != MAX_BASE36_POWER_TABLE_ENTRIES);
 
     if ((size_t)BIGNUM_LEN(power) <= xn) {
         /*
@@ -5093,7 +5146,7 @@ rb_big2str1(VALUE x, int base)
         invalid_radix(base);
 
     if (xn >= LONG_MAX/BITSPERDIG) {
-        rb_raise(rb_eRangeError, "bignum too big to convert into `string'");
+        rb_raise(rb_eRangeError, "bignum too big to convert into 'string'");
     }
 
     if (POW2_P(base)) {
@@ -5129,7 +5182,7 @@ big2ulong(VALUE x, const char *type)
     if (len == 0)
         return 0;
     if (BIGSIZE(x) > sizeof(long)) {
-        rb_raise(rb_eRangeError, "bignum too big to convert into `%s'", type);
+        rb_raise(rb_eRangeError, "bignum too big to convert into '%s'", type);
     }
     ds = BDIGITS(x);
 #if SIZEOF_LONG <= SIZEOF_BDIGIT
@@ -5172,7 +5225,7 @@ rb_big2long(VALUE x)
         if (num <= 1+(unsigned long)(-(LONG_MIN+1)))
             return -(long)(num-1)-1;
     }
-    rb_raise(rb_eRangeError, "bignum too big to convert into `long'");
+    rb_raise(rb_eRangeError, "bignum too big to convert into 'long'");
 }
 
 #if HAVE_LONG_LONG
@@ -5190,7 +5243,7 @@ big2ull(VALUE x, const char *type)
     if (len == 0)
         return 0;
     if (BIGSIZE(x) > SIZEOF_LONG_LONG)
-        rb_raise(rb_eRangeError, "bignum too big to convert into `%s'", type);
+        rb_raise(rb_eRangeError, "bignum too big to convert into '%s'", type);
 #if SIZEOF_LONG_LONG <= SIZEOF_BDIGIT
     num = (unsigned LONG_LONG)ds[0];
 #else
@@ -5231,7 +5284,7 @@ rb_big2ll(VALUE x)
         if (num <= 1+(unsigned LONG_LONG)(-(LLONG_MIN+1)))
             return -(LONG_LONG)(num-1)-1;
     }
-    rb_raise(rb_eRangeError, "bignum too big to convert into `long long'");
+    rb_raise(rb_eRangeError, "bignum too big to convert into 'long long'");
 }
 
 #endif  /* HAVE_LONG_LONG */
@@ -5494,10 +5547,10 @@ big_op(VALUE x, VALUE y, enum big_op_t op)
     n = FIX2INT(rel);
 
     switch (op) {
-        case big_op_gt: return RBOOL(n >  0);
-        case big_op_ge: return RBOOL(n >= 0);
-        case big_op_lt: return RBOOL(n <  0);
-        case big_op_le: return RBOOL(n <= 0);
+      case big_op_gt: return RBOOL(n >  0);
+      case big_op_ge: return RBOOL(n >= 0);
+      case big_op_lt: return RBOOL(n <  0);
+      case big_op_le: return RBOOL(n <= 0);
     }
     return Qundef;
 }
@@ -5653,7 +5706,7 @@ bigsub_int(VALUE x, long y0)
     zds = BDIGITS(z);
 
 #if SIZEOF_BDIGIT >= SIZEOF_LONG
-    assert(xn == zn);
+    RUBY_ASSERT(xn == zn);
     num = (BDIGIT_DBL_SIGNED)xds[0] - y;
     if (xn == 1 && num < 0) {
         BIGNUM_NEGATE(z);
@@ -5716,7 +5769,7 @@ bigsub_int(VALUE x, long y0)
     goto finish;
 
   finish:
-    assert(num == 0 || num == -1);
+    RUBY_ASSERT(num == 0 || num == -1);
     if (num < 0) {
         get2comp(z);
         BIGNUM_NEGATE(z);
@@ -5901,6 +5954,8 @@ bigsq(VALUE x)
     BDIGIT *xds, *zds;
 
     xn = BIGNUM_LEN(x);
+    if (MUL_OVERFLOW_LONG_P(2, xn))
+        rb_raise(rb_eArgError, "square overflow");
     zn = 2 * xn;
 
     z = bignew(zn, 1);
@@ -5929,6 +5984,8 @@ bigmul0(VALUE x, VALUE y)
 
     xn = BIGNUM_LEN(x);
     yn = BIGNUM_LEN(y);
+    if (ADD_OVERFLOW_LONG_P(xn, yn))
+        rb_raise(rb_eArgError, "multiplication overflow");
     zn = xn + yn;
 
     z = bignew(zn, BIGNUM_SIGN(x)==BIGNUM_SIGN(y));
@@ -6274,8 +6331,7 @@ rb_big_pow(VALUE x, VALUE y)
         y = bignorm(y);
         if (FIXNUM_P(y))
             goto again;
-        rb_warn("in a**b, b may be too big");
-        d = rb_big2dbl(y);
+        rb_raise(rb_eArgError, "exponent is too large");
     }
     else if (FIXNUM_P(y)) {
         yy = FIX2LONG(y);
@@ -6291,13 +6347,17 @@ rb_big_pow(VALUE x, VALUE y)
             VALUE z = 0;
             SIGNED_VALUE mask;
             const size_t xbits = rb_absint_numwords(x, 1, NULL);
-            const size_t BIGLEN_LIMIT = 32*1024*1024;
+#if SIZEOF_SIZE_T == 4
+            const size_t BIGLEN_LIMIT = 1ULL << 31; // 2 GB
+#else // SIZEOF_SIZE_T == 8
+            const size_t BIGLEN_LIMIT = 1ULL << 34; // 16 GB
+#endif
 
             if (xbits == (size_t)-1 ||
                 (xbits > BIGLEN_LIMIT) ||
+                MUL_OVERFLOW_LONG_P(yy, xbits) ||
                 (xbits * yy > BIGLEN_LIMIT)) {
-                rb_warn("in a**b, b may be too big");
-                d = (double)yy;
+                rb_raise(rb_eArgError, "exponent is too large");
             }
             else {
                 for (mask = FIXNUM_MAX + 1; mask; mask >>= 1) {
@@ -6326,7 +6386,7 @@ bigand_int(VALUE x, long xn, BDIGIT hibitsx, long y)
     BDIGIT hibitsy;
 
     if (y == 0) return INT2FIX(0);
-    if (xn == 0) return hibitsx ? LONG2NUM(y) : 0;
+    if (xn == 0) return hibitsx ? LONG2NUM(y) : INT2FIX(0);
     hibitsy = 0 <= y ? 0 : BDIGMAX;
     xds = BDIGITS(x);
 #if SIZEOF_BDIGIT >= SIZEOF_LONG
@@ -6738,6 +6798,73 @@ rb_big_aref(VALUE x, VALUE y)
 }
 
 VALUE
+rb_big_aref2(VALUE x, VALUE beg, VALUE len)
+{
+    BDIGIT *xds, *vds;
+    VALUE v;
+    size_t copy_begin, xn, shift;
+    ssize_t begin, length, end;
+    bool negative_add_one;
+
+    beg = rb_to_int(beg);
+    len = rb_to_int(len);
+    length = NUM2SSIZET(len);
+    begin = NUM2SSIZET(beg);
+    end = NUM2SSIZET(rb_int_plus(beg, len));
+    shift = begin < 0 ? -begin : 0;
+    xn = BIGNUM_LEN(x);
+    xds = BDIGITS(x);
+
+    if (length < 0) return rb_big_rshift(x, beg);
+    if (length == 0 || end <= 0) return INT2FIX(0);
+    if (begin < 0) begin = 0;
+
+    if ((size_t)(end - 1) / BITSPERDIG >= xn) {
+        /* end > xn * BITSPERDIG */
+        end = xn * BITSPERDIG;
+    }
+
+    if ((size_t)begin / BITSPERDIG < xn) {
+        /* begin < xn * BITSPERDIG */
+        size_t shift_bits, copy_end;
+        copy_begin = begin / BITSPERDIG;
+        shift_bits = begin % BITSPERDIG;
+        copy_end = (end - 1) / BITSPERDIG + 1;
+        v = bignew(copy_end - copy_begin, 1);
+        vds = BDIGITS(v);
+        MEMCPY(vds, xds + copy_begin, BDIGIT, copy_end - copy_begin);
+        negative_add_one = (vds[0] & ((1 << shift_bits) - 1)) == 0;
+        v = bignorm(v);
+        if (shift_bits) v = rb_int_rshift(v, SIZET2NUM(shift_bits));
+    }
+    else {
+        /* Out of range */
+        v = INT2FIX(0);
+        negative_add_one = false;
+        copy_begin = begin = end = 0;
+    }
+
+    if (BIGNUM_NEGATIVE_P(x)) {
+        size_t mask_size = length - shift;
+        VALUE mask = rb_int_minus(rb_int_lshift(INT2FIX(1), SIZET2NUM(mask_size)), INT2FIX(1));
+        v = rb_int_xor(v, mask);
+        for (size_t i = 0; negative_add_one && i < copy_begin; i++) {
+            if (xds[i]) negative_add_one = false;
+        }
+        if (negative_add_one) v = rb_int_plus(v, INT2FIX(1));
+        v = rb_int_and(v, mask);
+    }
+    else {
+        size_t mask_size = (size_t)end - begin;
+        VALUE mask = rb_int_minus(rb_int_lshift(INT2FIX(1), SIZET2NUM(mask_size)), INT2FIX(1));
+        v = rb_int_and(v, mask);
+    }
+    RB_GC_GUARD(x);
+    if (shift) v = rb_int_lshift(v, SSIZET2NUM(shift));
+    return v;
+}
+
+VALUE
 rb_big_hash(VALUE x)
 {
     st_index_t hash;
@@ -6871,63 +6998,11 @@ BDIGIT rb_bdigit_dbl_isqrt(BDIGIT_DBL);
 # define BDIGIT_DBL_TO_DOUBLE(n) (double)(n)
 #endif
 
-static BDIGIT *
-estimate_initial_sqrt(VALUE *xp, const size_t xn, const BDIGIT *nds, size_t len)
-{
-    enum {dbl_per_bdig = roomof(DBL_MANT_DIG,BITSPERDIG)};
-    const int zbits = nlz(nds[len-1]);
-    VALUE x = *xp = bignew_1(0, xn, 1); /* division may release the GVL */
-    BDIGIT *xds = BDIGITS(x);
-    BDIGIT_DBL d = bary2bdigitdbl(nds+len-dbl_per_bdig, dbl_per_bdig);
-    BDIGIT lowbits = 1;
-    int rshift = (int)((BITSPERDIG*2-zbits+(len&BITSPERDIG&1) - DBL_MANT_DIG + 1) & ~1);
-    double f;
-
-    if (rshift > 0) {
-        lowbits = (BDIGIT)d & ~(~(BDIGIT)1U << rshift);
-        d >>= rshift;
-    }
-    else if (rshift < 0) {
-        d <<= -rshift;
-        d |= nds[len-dbl_per_bdig-1] >> (BITSPERDIG+rshift);
-    }
-    f = sqrt(BDIGIT_DBL_TO_DOUBLE(d));
-    d = (BDIGIT_DBL)ceil(f);
-    if (BDIGIT_DBL_TO_DOUBLE(d) == f) {
-        if (lowbits || (lowbits = !bary_zero_p(nds, len-dbl_per_bdig)))
-            ++d;
-    }
-    else {
-        lowbits = 1;
-    }
-    rshift /= 2;
-    rshift += (2-(len&1))*BITSPERDIG/2;
-    if (rshift >= 0) {
-        if (nlz((BDIGIT)d) + rshift >= BITSPERDIG) {
-            /* (d << rshift) does cause overflow.
-             * example: Integer.sqrt(0xffff_ffff_ffff_ffff ** 2)
-             */
-            d = ~(BDIGIT_DBL)0;
-        }
-        else {
-            d <<= rshift;
-        }
-    }
-    BDIGITS_ZERO(xds, xn-2);
-    bdigitdbl2bary(&xds[xn-2], 2, d);
-
-    if (!lowbits) return NULL; /* special case, exact result */
-    return xds;
-}
-
 VALUE
 rb_big_isqrt(VALUE n)
 {
     BDIGIT *nds = BDIGITS(n);
     size_t len = BIGNUM_LEN(n);
-    size_t xn = (len+1) / 2;
-    VALUE x;
-    BDIGIT *xds;
 
     if (len <= 2) {
         BDIGIT sq = rb_bdigit_dbl_isqrt(bary2bdigitdbl(nds, len));
@@ -6937,25 +7012,19 @@ rb_big_isqrt(VALUE n)
         return ULONG2NUM(sq);
 #endif
     }
-    else if ((xds = estimate_initial_sqrt(&x, xn, nds, len)) != 0) {
-        size_t tn = xn + BIGDIVREM_EXTRA_WORDS;
-        VALUE t = bignew_1(0, tn, 1);
-        BDIGIT *tds = BDIGITS(t);
-        tn = BIGNUM_LEN(t);
-
-        /* t = n/x */
-        while (bary_divmod_branch(tds, tn, NULL, 0, nds, len, xds, xn),
-               bary_cmp(tds, tn, xds, xn) < 0) {
-            int carry;
-            BARY_TRUNC(tds, tn);
-            /* x = (x+t)/2 */
-            carry = bary_add(xds, xn, xds, xn, tds, tn);
-            bary_small_rshift(xds, xds, xn, 1, carry);
-            tn = BIGNUM_LEN(t);
+    else {
+        size_t shift = FIX2LONG(rb_big_bit_length(n)) / 4;
+        VALUE n2 = rb_int_rshift(n, SIZET2NUM(2 * shift));
+        VALUE x = FIXNUM_P(n2) ? LONG2FIX(rb_ulong_isqrt(FIX2ULONG(n2))) : rb_big_isqrt(n2);
+        /* x = (x+n/x)/2 */
+        x = rb_int_plus(rb_int_lshift(x, SIZET2NUM(shift - 1)), rb_int_idiv(rb_int_rshift(n, SIZET2NUM(shift + 1)), x));
+        VALUE xx = rb_int_mul(x, x);
+        while (rb_int_gt(xx, n)) {
+            xx = rb_int_minus(xx, rb_int_minus(rb_int_plus(x, x), INT2FIX(1)));
+            x = rb_int_minus(x, INT2FIX(1));
         }
+        return x;
     }
-    RBASIC_SET_CLASS_RAW(x, rb_cInteger);
-    return x;
 }
 
 #if USE_GMP
@@ -6994,14 +7063,14 @@ int_pow_tmp3(VALUE x, VALUE y, VALUE m, int nega_flg)
     if (FIXNUM_P(y)) {
        y = rb_int2big(FIX2LONG(y));
     }
-    assert(RB_BIGNUM_TYPE_P(m));
+    RUBY_ASSERT(RB_BIGNUM_TYPE_P(m));
     xn = BIGNUM_LEN(x);
     yn = BIGNUM_LEN(y);
     mn = BIGNUM_LEN(m);
     zn = mn;
     z = bignew(zn, 1);
     bary_powm_gmp(BDIGITS(z), zn, BDIGITS(x), xn, BDIGITS(y), yn, BDIGITS(m), mn);
-    if (nega_flg & BIGNUM_POSITIVE_P(z)) {
+    if (nega_flg && BIGNUM_POSITIVE_P(z) && !BIGZEROP(z)) {
         z = rb_big_minus(z, m);
     }
     RB_GC_GUARD(x);
@@ -7029,7 +7098,7 @@ int_pow_tmp3(VALUE x, VALUE y, VALUE m, int nega_flg)
         x = rb_int_modulo(x, m);
     }
 
-    if (nega_flg && rb_int_positive_p(tmp)) {
+    if (nega_flg && rb_int_positive_p(tmp) && !rb_int_zero_p(tmp)) {
         tmp = rb_int_minus(tmp, m);
     }
     return tmp;
@@ -7141,6 +7210,11 @@ rb_int_powm(int const argc, VALUE * const argv, VALUE const num)
             rb_raise(rb_eTypeError, "Integer#pow() 2nd argument not allowed unless all arguments are integers");
         }
 
+        if (rb_int_zero_p(a) && !rb_int_zero_p(b)) {
+            /* shortcut; 0**x => 0 except for x == 0 */
+            return INT2FIX(0);
+        }
+
         if (rb_int_negative_p(m)) {
             m = rb_int_uminus(m);
             nega_flg = 1;
diff --git a/bin/gem b/bin/gem
index 1c16ea7ddd..3ac1d9e623 100755
--- a/bin/gem
+++ b/bin/gem
@@ -1,4 +1,6 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
+
 #--
 # Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
 # All rights reserved.
diff --git a/bootstraptest/runner.rb b/bootstraptest/runner.rb
index 9699b10bc0..04de0c93b9 100755
--- a/bootstraptest/runner.rb
+++ b/bootstraptest/runner.rb
@@ -6,7 +6,6 @@
 # Never use optparse in this file.
 # Never use test/unit in this file.
 # Never use Ruby extensions in this file.
-# Maintain Ruby 1.8 compatibility for now
 
 $start_time = Time.now
 
@@ -17,6 +16,7 @@ rescue LoadError
   $:.unshift File.join(File.dirname(__FILE__), '../lib')
   retry
 end
+require_relative '../tool/lib/test/jobserver'
 
 if !Dir.respond_to?(:mktmpdir)
   # copied from lib/tmpdir.rb
@@ -61,7 +61,7 @@ if !Dir.respond_to?(:mktmpdir)
 end
 
 # Configuration
-BT = Struct.new(:ruby,
+bt = Struct.new(:ruby,
                 :verbose,
                 :color,
                 :tty,
@@ -73,9 +73,57 @@ BT = Struct.new(:ruby,
                 :failed,
                 :reset,
                 :columns,
+                :window_width,
                 :width,
+                :indent,
                 :platform,
-                ).new
+                :timeout,
+                :timeout_scale,
+                :launchable_test_reports
+                )
+BT = Class.new(bt) do
+  def indent=(n)
+    super
+    if (self.columns ||= 0) < n
+      $stderr.print(' ' * (n - self.columns))
+    end
+    self.columns = indent
+  end
+
+  def putc(c)
+    unless self.quiet
+      if self.window_width == nil
+        unless w = ENV["COLUMNS"] and (w = w.to_i) > 0
+          w = 80
+        end
+        w -= 1
+        self.window_width = w
+      end
+      if self.window_width and self.columns >= self.window_width
+        $stderr.print "\n", " " * (self.indent ||= 0)
+        self.columns = indent
+      end
+      $stderr.print c
+      $stderr.flush
+      self.columns += 1
+    end
+  end
+
+  def wn=(wn)
+    unless wn == 1
+      wn = Test::JobServer.max_jobs(wn > 0 ? wn : 1024, ENV.delete("MAKEFLAGS")) || wn
+      if wn <= 0
+        require 'etc'
+        wn = [Etc.nprocessors / 2, 1].max
+      end
+    end
+    super wn
+  end
+
+  def apply_timeout_scale(timeout)
+    timeout&.*(timeout_scale)
+  end
+end.new
 
 BT_STATE = Struct.new(:count, :error).new
 
@@ -87,7 +135,13 @@ def main
   BT.color = nil
   BT.tty = nil
   BT.quiet = false
-  BT.wn = 1
+  BT.timeout = 180
+  BT.timeout_scale = 1
+  if (ts = (ENV["RUBY_TEST_TIMEOUT_SCALE"] || ENV["RUBY_TEST_SUBPROCESS_TIMEOUT_SCALE"]).to_i) > 1
+    BT.timeout_scale *= ts
+  end
+
+  # BT.wn = 1
   dir = nil
   quiet = false
   tests = nil
@@ -117,19 +171,18 @@ def main
       warn "unknown --tty argument: #$3" if $3
       BT.tty = !$1 || !$2
       true
-    when /\A(-q|--q(uiet))\z/
+    when /\A(-q|--q(uiet)?)\z/
       quiet = true
       BT.quiet = true
       true
     when /\A-j(\d+)?/
-      wn = $1.to_i
-      if wn <= 0
-        require 'etc'
-        wn = [Etc.nprocessors / 2, 1].max
-      end
-      BT.wn = wn
+      BT.wn = $1.to_i
       true
-    when /\A(-v|--v(erbose))\z/
+    when /\A--timeout=(\d+(?:_\d+)*(?:\.\d+(?:_\d+)*)?)(?::(\d+(?:_\d+)*(?:\.\d+(?:_\d+)*)?))?/
+      BT.timeout = $1.to_f
+      BT.timeout_scale = $2.to_f if defined?($2)
+      true
+    when /\A(-v|--v(erbose)?)\z/
       BT.verbose = true
       BT.quiet = false
       true
@@ -141,6 +194,7 @@ Usage: #{File.basename($0, '.*')} --ruby=PATH [--sets=NAME,NAME,...]
                                     default: /tmp/bootstraptestXXXXX.tmpwd
         --color[=WHEN]              Colorize the output.  WHEN defaults to 'always'
                                     or can be 'never' or 'auto'.
+        --timeout=TIMEOUT           Default timeout in seconds.
     -s, --stress                    stress test.
     -v, --verbose                   Output test name before exec.
     -q, --quiet                     Don\'t print header message.
@@ -149,6 +203,31 @@ End
       exit true
     when /\A-j/
       true
+    when /--launchable-test-reports=(.*)/
+      if File.exist?($1)
+        # To protect files from overwritten, do nothing when the file exists.
+        return true
+      end
+
+      begin
+        require_relative '../tool/lib/launchable'
+      rescue LoadError
+        # The following error sometimes happens, so we're going to skip writing Launchable report files in this case.
+        #
+        # ```
+        # /tmp/tmp.bISss9CtXZ/.ext/common/json/ext.rb:15:in 'Kernel#require':
+        #   /tmp/tmp.bISss9CtXZ/.ext/x86_64-linux/json/ext/parser.so:
+        #     undefined symbol: ruby_abi_version - ruby_abi_version (LoadError)
+        # ```
+        #
+        return true
+      end
+      BT.launchable_test_reports = writer = Launchable::JsonStreamWriter.new($1)
+      writer.write_array('testCases')
+      at_exit {
+        writer.close
+      }
+      true
     else
       false
     end
@@ -158,11 +237,12 @@ End
   end
   tests ||= ARGV
   tests = Dir.glob("#{File.dirname($0)}/test_*.rb").sort if tests.empty?
-  pathes = tests.map {|path| File.expand_path(path) }
+  paths = tests.map {|path| File.expand_path(path) }
 
   BT.progress = %w[- \\ | /]
   BT.progress_bs = "\b" * BT.progress[0].size
   BT.tty = $stderr.tty? if BT.tty.nil?
+  BT.wn ||= /-j(\d+)?/ =~ (ENV["MAKEFLAGS"] || ENV["MFLAGS"]) ? $1.to_i : 1
 
   case BT.color
   when nil
@@ -191,7 +271,7 @@ End
     if defined?(RUBY_DESCRIPTION)
       puts "Driver is #{RUBY_DESCRIPTION}"
     elsif defined?(RUBY_PATCHLEVEL)
-      puts "Driver is ruby #{RUBY_VERSION} (#{RUBY_RELEASE_DATE}#{RUBY_PLATFORM}) [#{RUBY_PLATFORM}]"
+      puts "Driver is ruby #{RUBY_VERSION} (#{RUBY_RELEASE_DATE}#{RUBY_PATCHLEVEL}) [#{RUBY_PLATFORM}]"
     else
       puts "Driver is ruby #{RUBY_VERSION} (#{RUBY_RELEASE_DATE}) [#{RUBY_PLATFORM}]"
     end
@@ -201,7 +281,7 @@ End
   end
 
   in_temporary_working_directory(dir) do
-    exec_test pathes
+    exec_test paths
   end
 end
 
@@ -213,8 +293,8 @@ def erase(e = true)
   end
 end
 
-def load_test pathes
-  pathes.each do |path|
+def load_test paths
+  paths.each do |path|
     load File.expand_path(path)
   end
 end
@@ -240,19 +320,20 @@ def concurrent_exec_test
     end
   end
 
-  $stderr.print ' ' unless BT.quiet
+  BT.indent = 1
   aq.close
   i = 1
   term_wn = 0
   begin
     while BT.wn != term_wn
       if r = rq.pop
+        BT_STATE.count += 1
         case
         when BT.quiet
         when BT.tty
           $stderr.print "#{BT.progress_bs}#{BT.progress[(i+=1) % BT.progress.size]}"
         else
-          $stderr.print '.'
+          BT.putc '.'
         end
       else
         term_wn += 1
@@ -264,17 +345,70 @@ def concurrent_exec_test
   end
 end
 
-def exec_test(pathes)
+##
+# Module for writing a test file for uploading test results into Launchable.
+# In bootstraptest, we aggregate the test results based on file level.
+module Launchable
+  @@last_test_name = nil
+  @@failure_log = ''
+  @@duration = 0
+
+  def show_progress(message = '')
+    faildesc, t = super
+
+    if writer = BT.launchable_test_reports
+      if faildesc
+        @@failure_log += faildesc
+      end
+      repo_path = File.expand_path("#{__dir__}/../")
+      relative_path = File.join(__dir__, self.path).delete_prefix("#{repo_path}/")
+      if @@last_test_name != nil && @@last_test_name != relative_path
+        # The test path is a URL-encoded representation.
+        # https://github.com/launchableinc/cli/blob/v1.81.0/launchable/testpath.py#L18
+        test_path = "#{encode_test_path_component("file")}=#{encode_test_path_component(@@last_test_name)}"
+        if @@failure_log.size > 0
+          status = 'TEST_FAILED'
+        else
+          status = 'TEST_PASSED'
+        end
+        writer.write_object(
+          {
+            testPath: test_path,
+            status: status,
+            duration: t,
+            createdAt: Time.now.to_s,
+            stderr: @@failure_log,
+            stdout: nil,
+            data: {
+              lineNumber: self.lineno
+            }
+          }
+        )
+        @@duration = 0
+        @@failure_log = ''
+      end
+      @@last_test_name = relative_path
+      @@duration += t
+    end
+  end
+
+  private
+  def encode_test_path_component component
+    component.to_s.gsub('%', '%25').gsub('=', '%3D').gsub('#', '%23').gsub('&', '%26')
+  end
+end
+
+def exec_test(paths)
   # setup
-  load_test pathes
+  load_test paths
   BT_STATE.count = 0
   BT_STATE.error = 0
   BT.columns = 0
-  BT.width = pathes.map {|path| File.basename(path).size}.max + 2
+  BT.width = paths.map {|path| File.basename(path).size}.max + 2
 
   # execute tests
   if BT.wn > 1
-    concurrent_exec_test if BT.wn > 1
+    concurrent_exec_test
   else
     prev_basename = nil
     Assertion.all.each do |basename, assertions|
@@ -340,6 +474,7 @@ def target_platform
 end
 
 class Assertion < Struct.new(:src, :path, :lineno, :proc)
+  prepend Launchable
   @count = 0
   @all = Hash.new{|h, k| h[k] = []}
   @errbuf = []
@@ -363,7 +498,7 @@ class Assertion < Struct.new(:src, :path, :lineno, :proc)
   def initialize(*args)
     super
     self.class.add self
-    @category = self.path.match(/test_(.+)\.rb/)[1]
+    @category = self.path[/\Atest_(.+)\.rb\z/, 1]
   end
 
   def call
@@ -414,9 +549,9 @@ class Assertion < Struct.new(:src, :path, :lineno, :proc)
       $stderr.print "#{BT.progress_bs}#{BT.progress[BT_STATE.count % BT.progress.size]}"
     end
 
-    t = Time.now if BT.verbose
+    t = Time.now if BT.verbose || BT.launchable_test_reports
     faildesc, errout = with_stderr {yield}
-    t = Time.now - t if BT.verbose
+    t = Time.now - t if BT.verbose || BT.launchable_test_reports
 
     if !faildesc
       # success
@@ -427,7 +562,7 @@ class Assertion < Struct.new(:src, :path, :lineno, :proc)
       elsif BT.verbose
         $stderr.printf(". %.3f\n", t)
       else
-        $stderr.print '.'
+        BT.putc '.'
       end
     else
       $stderr.print "#{BT.failed}F"
@@ -443,6 +578,8 @@ class Assertion < Struct.new(:src, :path, :lineno, :proc)
         $stderr.printf("%-*s%s", BT.width, path, BT.progress[BT_STATE.count % BT.progress.size])
       end
     end
+
+    [faildesc, t]
   rescue Interrupt
     $stderr.puts "\##{@id} #{path}:#{lineno}"
     raise
@@ -461,14 +598,22 @@ class Assertion < Struct.new(:src, :path, :lineno, :proc)
     end
   end
 
-  def get_result_string(opt = '', **argh)
+  class Timeout < StandardError; end
+
+  def get_result_string(opt = '', timeout: BT.timeout, **argh)
     if BT.ruby
+      timeout = BT.apply_timeout_scale(timeout)
       filename = make_srcfile(**argh)
       begin
         kw = self.err ? {err: self.err} : {}
         out = IO.popen("#{BT.ruby} -W0 #{opt} #{filename}", **kw)
         pid = out.pid
-        out.read.tap{ Process.waitpid(pid); out.close }
+        th = Thread.new {out.read.tap {Process.waitpid(pid); out.close}}
+        if th.join(timeout)
+          th.value
+        else
+          Timeout.new("timed out after #{timeout} seconds")
+        end
       ensure
         raise Interrupt if $? and $?.signaled? && $?.termsig == Signal.list["INT"]
 
@@ -486,9 +631,14 @@ class Assertion < Struct.new(:src, :path, :lineno, :proc)
   def make_srcfile(frozen_string_literal: nil)
     filename = "bootstraptest.#{self.path}_#{self.lineno}_#{self.id}.rb"
     File.open(filename, 'w') {|f|
-      f.puts "#frozen_string_literal:true" if frozen_string_literal
-      f.puts "GC.stress = true" if $stress
-      f.puts "print(begin; #{self.src}; end)"
+      f.puts "#frozen_string_literal:#{frozen_string_literal}" unless frozen_string_literal.nil?
+      if $stress
+        f.puts "GC.stress = true" if $stress
+      else
+        f.puts ""
+      end
+      f.puts "class BT_Skip < Exception; end; def skip(msg) = raise(BT_Skip, msg.to_s)"
+      f.puts "print(begin; #{self.src}; rescue BT_Skip; $!.message; end)"
     }
     filename
   end
@@ -502,9 +652,9 @@ def add_assertion src, pr
   Assertion.new(src, path, lineno, pr)
 end
 
-def assert_equal(expected, testsrc, message = '', opt = '', **argh)
+def assert_equal(expected, testsrc, message = '', opt = '', **kwargs)
   add_assertion testsrc, -> as do
-    as.assert_check(message, opt, **argh) {|result|
+    as.assert_check(message, opt, **kwargs) {|result|
       if expected == result
         nil
       else
@@ -515,9 +665,9 @@ def assert_equal(expected, testsrc, message = '', opt = '', **argh)
   end
 end
 
-def assert_match(expected_pattern, testsrc, message = '')
+def assert_match(expected_pattern, testsrc, message = '', **argh)
   add_assertion testsrc, -> as do
-    as.assert_check(message) {|result|
+    as.assert_check(message, **argh) {|result|
       if expected_pattern =~ result
         nil
       else
@@ -549,8 +699,9 @@ def assert_valid_syntax(testsrc, message = '')
   end
 end
 
-def assert_normal_exit(testsrc, *rest, timeout: nil, **opt)
+def assert_normal_exit(testsrc, *rest, timeout: BT.timeout, **opt)
   add_assertion testsrc, -> as do
+    timeout = BT.apply_timeout_scale(timeout)
     message, ignore_signals = rest
     message ||= ''
     as.show_progress(message) {
@@ -559,23 +710,19 @@ def assert_normal_exit(testsrc, *rest, timeout: nil, **opt)
       timeout_signaled = false
       logfile = "assert_normal_exit.#{as.path}.#{as.lineno}.log"
 
-      begin
-        err = open(logfile, "w")
-        io = IO.popen("#{BT.ruby} -W0 #{filename}", err: err)
-        pid = io.pid
-        th = Thread.new {
-          io.read
-          io.close
-          $?
-        }
-        if !th.join(timeout)
-          Process.kill :KILL, pid
-          timeout_signaled = true
-        end
-        status = th.value
-      ensure
-        err.close
+      io = IO.popen("#{BT.ruby} -W0 #{filename}", err: logfile)
+      pid = io.pid
+      th = Thread.new {
+        io.read
+        io.close
+        $?
+      }
+      if !th.join(timeout)
+        Process.kill :KILL, pid
+        timeout_signaled = true
       end
+      status = th.value
+
       if status && status.signaled?
         signo = status.termsig
         signame = Signal.list.invert[signo]
@@ -604,9 +751,7 @@ end
 
 def assert_finish(timeout_seconds, testsrc, message = '')
   add_assertion testsrc, -> as do
-    if defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled? # for --jit-wait
-      timeout_seconds *= 3
-    end
+    timeout_seconds = BT.apply_timeout_scale(timeout_seconds)
 
     as.show_progress(message) {
       faildesc = nil
@@ -662,6 +807,8 @@ end
 
 def pretty(src, desc, result)
   src = src.sub(/\A\s*\n/, '')
+  lines = src.lines
+  src = lines[0..20].join + "(...snip)\n" if lines.size > 20
   (/\n/ =~ src ? "\n#{adjust_indent(src)}" : src) + "  #=> #{desc}"
 end
 
@@ -719,4 +866,12 @@ def check_coredump
   end
 end
 
+def yjit_enabled?
+  ENV.key?('RUBY_YJIT_ENABLE') || ENV.fetch('RUN_OPTS', '').include?('yjit') || BT.ruby.include?('yjit')
+end
+
+def zjit_enabled?
+  ENV.key?('RUBY_ZJIT_ENABLE') || ENV.fetch('RUN_OPTS', '').include?('zjit') || BT.ruby.include?('zjit')
+end
+
 exit main
diff --git a/bootstraptest/test_attr.rb b/bootstraptest/test_attr.rb
index 721a847145..3cb9d3eb39 100644
--- a/bootstraptest/test_attr.rb
+++ b/bootstraptest/test_attr.rb
@@ -34,3 +34,19 @@ assert_equal %{ok}, %{
     print "ok"
   end
 }, '[ruby-core:15120]'
+
+assert_equal %{ok}, %{
+  class Big
+    attr_reader :foo
+    def initialize
+      @foo = "ok"
+    end
+  end
+
+  obj = Big.new
+  100.times do |i|
+    obj.instance_variable_set(:"@ivar_\#{i}", i)
+  end
+
+  Big.new.foo
+}
diff --git a/bootstraptest/test_autoload.rb b/bootstraptest/test_autoload.rb
index 9e0850bc52..de66f1f3ee 100644
--- a/bootstraptest/test_autoload.rb
+++ b/bootstraptest/test_autoload.rb
@@ -11,7 +11,7 @@ assert_equal 'ok', %q{
 }, '[ruby-dev:43816]'
 
 assert_equal 'ok', %q{
-  open('zzz2.rb', 'w') {|f| f.puts '' }
+  File.write('zzz2.rb', '')
   instance_eval do
     autoload :ZZZ, './zzz2.rb'
     begin
@@ -23,7 +23,7 @@ assert_equal 'ok', %q{
 }, '[ruby-dev:43816]'
 
 assert_equal 'ok', %q{
-  open('zzz3.rb', 'w') {|f| f.puts 'class ZZZ; def self.ok;:ok;end;end'}
+  File.write('zzz3.rb', "class ZZZ; def self.ok;:ok;end;end\n")
   instance_eval do
     autoload :ZZZ, './zzz3.rb'
     ZZZ.ok
@@ -31,20 +31,20 @@ assert_equal 'ok', %q{
 }, '[ruby-dev:43816]'
 
 assert_equal 'ok', %q{
-  open("zzz4.rb", "w") {|f| f.puts "class ZZZ; def self.ok;:ok;end;end"}
+  File.write("zzz4.rb", "class ZZZ; def self.ok;:ok;end;end\n")
   autoload :ZZZ, "./zzz4.rb"
   ZZZ.ok
 }
 
 assert_equal 'ok', %q{
-  open("zzz5.rb", "w") {|f| f.puts "class ZZZ; def self.ok;:ok;end;end"}
+  File.write("zzz5.rb", "class ZZZ; def self.ok;:ok;end;end\n")
   autoload :ZZZ, "./zzz5.rb"
   require "./zzz5.rb"
   ZZZ.ok
 }
 
 assert_equal 'okok', %q{
-  open("zzz6.rb", "w") {|f| f.puts "class ZZZ; def self.ok;:ok;end;end"}
+  File.write("zzz6.rb", "class ZZZ; def self.ok;:ok;end;end\n")
   autoload :ZZZ, "./zzz6.rb"
   t1 = Thread.new {ZZZ.ok}
   t2 = Thread.new {ZZZ.ok}
@@ -60,7 +60,7 @@ assert_finish 5, %q{
 }, '[ruby-core:21696]'
 
 assert_equal 'A::C', %q{
-  open("zzz7.rb", "w") {}
+  File.write("zzz7.rb", "")
   class A
     autoload :C, "./zzz7"
     class C
diff --git a/bootstraptest/test_eval.rb b/bootstraptest/test_eval.rb
index a9f389c673..20bd9615f4 100644
--- a/bootstraptest/test_eval.rb
+++ b/bootstraptest/test_eval.rb
@@ -217,7 +217,7 @@ assert_equal %q{[10, main]}, %q{
 }
 
 %w[break next redo].each do |keyword|
-  assert_match %r"Can't escape from eval with #{keyword}\b", %{
+  assert_match %r"Invalid #{keyword}\b", %{
     $stderr = STDOUT
     begin
       eval "0 rescue #{keyword}"
@@ -227,6 +227,16 @@ assert_equal %q{[10, main]}, %q{
   }, '[ruby-dev:31372]'
 end
 
+assert_normal_exit %{
+  $stderr = STDOUT
+  5000.times do
+    begin
+      eval "0 rescue break"
+    rescue SyntaxError
+    end
+  end
+}
+
 assert_normal_exit %q{
   $stderr = STDOUT
   class Foo
@@ -354,3 +364,34 @@ assert_normal_exit %q{
   end
 }, 'check escaping the internal value th->base_block'
 
+assert_equal "false", <<~RUBY, "literal strings are mutable", "--disable-frozen-string-literal"
+  eval("'test'").frozen?
+RUBY
+
+assert_equal "false", <<~RUBY, "literal strings are mutable", "--disable-frozen-string-literal", frozen_string_literal: true
+  eval("'test'").frozen?
+RUBY
+
+assert_equal "true", <<~RUBY, "literal strings are frozen", "--enable-frozen-string-literal"
+  eval("'test'").frozen?
+RUBY
+
+assert_equal "true", <<~RUBY, "literal strings are frozen", "--enable-frozen-string-literal", frozen_string_literal: false
+  eval("'test'").frozen?
+RUBY
+
+assert_equal "false", <<~RUBY, "__FILE__ is mutable", "--disable-frozen-string-literal"
+  eval("__FILE__").frozen?
+RUBY
+
+assert_equal "false", <<~RUBY, "__FILE__ is mutable", "--disable-frozen-string-literal", frozen_string_literal: true
+  eval("__FILE__").frozen?
+RUBY
+
+assert_equal "true", <<~RUBY, "__FILE__ is frozen", "--enable-frozen-string-literal"
+  eval("__FILE__").frozen?
+RUBY
+
+assert_equal "true", <<~RUBY, "__FILE__ is frozen", "--enable-frozen-string-literal", frozen_string_literal: false
+  eval("__FILE__").frozen?
+RUBY
diff --git a/bootstraptest/test_exception.rb b/bootstraptest/test_exception.rb
index 0fb6f552b8..decfdc08a3 100644
--- a/bootstraptest/test_exception.rb
+++ b/bootstraptest/test_exception.rb
@@ -370,7 +370,7 @@ assert_equal %q{}, %q{
 }
 
 ##
-assert_match /undefined method `foo\'/, %q{#`
+assert_match /undefined method 'foo\'/, %q{#`
   STDERR.reopen(STDOUT)
   class C
     def inspect
diff --git a/bootstraptest/test_fiber.rb b/bootstraptest/test_fiber.rb
index 2614dd13bf..ae809a5936 100644
--- a/bootstraptest/test_fiber.rb
+++ b/bootstraptest/test_fiber.rb
@@ -37,3 +37,8 @@ assert_normal_exit %q{
 assert_normal_exit %q{
   Fiber.new(&Object.method(:class_eval)).resume("foo")
 }, '[ruby-dev:34128]'
+
+# [Bug #21400]
+assert_normal_exit %q{
+  Thread.new { Fiber.current.kill }.join
+}
diff --git a/bootstraptest/test_finalizer.rb b/bootstraptest/test_finalizer.rb
index 22a16b1220..ccfa0b55d6 100644
--- a/bootstraptest/test_finalizer.rb
+++ b/bootstraptest/test_finalizer.rb
@@ -6,3 +6,11 @@ ObjectSpace.define_finalizer(b1,proc{b1.inspect})
 ObjectSpace.define_finalizer(a2,proc{a1.inspect})
 ObjectSpace.define_finalizer(a1,proc{})
 }, '[ruby-dev:35778]'
+
+assert_equal 'true', %q{
+  obj = Object.new
+  id = obj.object_id
+
+  ObjectSpace.define_finalizer(obj, proc { |i| print(id == i) })
+  nil
+}
diff --git a/bootstraptest/test_flow.rb b/bootstraptest/test_flow.rb
index 35f19db588..15528a4213 100644
--- a/bootstraptest/test_flow.rb
+++ b/bootstraptest/test_flow.rb
@@ -363,7 +363,7 @@ assert_equal %q{[1, 2, 3, 5, 2, 3, 5, 7, 8]}, %q{$a = []; begin;  ; $a << 1
 ; $a << 8
 ; rescue Exception; $a << 99; end; $a}
 assert_equal %q{[1, 2, 6, 3, 5, 7, 8]}, %q{$a = []; begin;  ; $a << 1
-  o = "test"; $a << 2
+  o = "test".dup; $a << 2
   def o.test(a); $a << 3
     return a; $a << 4
   ensure; $a << 5
diff --git a/bootstraptest/test_fork.rb b/bootstraptest/test_fork.rb
index 83923dad97..860ef285d0 100644
--- a/bootstraptest/test_fork.rb
+++ b/bootstraptest/test_fork.rb
@@ -75,3 +75,30 @@ assert_equal '[1, 2]', %q{
   end
 }, '[ruby-dev:44005] [Ruby 1.9 - Bug #4950]'
 
+assert_equal 'ok', %q{
+  def now = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+
+  Thread.new do
+    loop { sleep 0.0001 }
+  end
+
+  10.times do
+    pid = fork{ exit!(0) }
+    deadline = now + 10
+    while true
+      _, status = Process.waitpid2(pid, Process::WNOHANG)
+      break if status
+      if now > deadline
+        Process.kill(:KILL, pid)
+        raise "failed"
+      end
+      sleep 0.001
+    end
+    unless status.success?
+      raise "child exited with status #{status}"
+    end
+  rescue NotImplementedError
+  end
+  :ok
+}, '[Bug #20670]'
+
diff --git a/bootstraptest/test_insns.rb b/bootstraptest/test_insns.rb
index 91fba9b011..9e2c4a52a7 100644
--- a/bootstraptest/test_insns.rb
+++ b/bootstraptest/test_insns.rb
@@ -92,7 +92,7 @@ tests = [
   [ 'intern',                   %q{ :"#{true}" }, ],
 
   [ 'newarray',    %q{ ["true"][0] }, ],
-  [ 'newarraykwsplat', %q{ [**{x:'true'}][0][:x] }, ],
+  [ 'pushtoarraykwsplat', %q{ [**{x:'true'}][0][:x] }, ],
   [ 'duparray',    %q{ [ true ][0] }, ],
   [ 'expandarray', %q{ y = [ true, false, nil ]; x, = y; x }, ],
   [ 'expandarray', %q{ y = [ true, false, nil ]; x, *z = y; x }, ],
@@ -214,9 +214,24 @@ tests = [
     'true'.freeze
   },
 
-  [ 'opt_newarray_max', %q{ [ ].max.nil? }, ],
-  [ 'opt_newarray_max', %q{ [1, x = 2, 3].max == 3 }, ],
-  [ 'opt_newarray_max', <<-'},', ], # {
+  [ 'opt_duparray_send', %q{ x = :a; [:a, :b].include?(x) }, ],
+  [ 'opt_duparray_send', <<-'},', ], # {
+    class Array
+      def include?(i)
+        i == 1
+      end
+    end
+    x = 1
+    [:a, :b].include?(x)
+  },
+
+  [ 'opt_newarray_send', %q{ ![ ].hash.nil? }, ],
+
+  [ 'opt_newarray_send', %q{ v=2; [1, Object.new, 2].include?(v) }, ],
+
+  [ 'opt_newarray_send', %q{ [ ].max.nil? }, ],
+  [ 'opt_newarray_send', %q{ [1, x = 2, 3].max == 3 }, ],
+  [ 'opt_newarray_send', <<-'},', ], # {
     class Array
       def max
         true
@@ -224,9 +239,9 @@ tests = [
     end
     [1, x = 2, 3].max
   },
-  [ 'opt_newarray_min', %q{ [ ].min.nil? }, ],
-  [ 'opt_newarray_min', %q{ [3, x = 2, 1].min == 1 }, ],
-  [ 'opt_newarray_min', <<-'},', ], # {
+  [ 'opt_newarray_send', %q{ [ ].min.nil? }, ],
+  [ 'opt_newarray_send', %q{ [3, x = 2, 1].min == 1 }, ],
+  [ 'opt_newarray_send', <<-'},', ], # {
     class Array
       def min
         true
@@ -234,6 +249,48 @@ tests = [
     end
     [3, x = 2, 1].min
   },
+  [ 'opt_newarray_send', %q{ v = 1.23; [v, v*2].pack("E*").unpack("E*") == [v, v*2] }, ],
+  [ 'opt_newarray_send', %q{ v = 4.56; b = +"x"; [v, v*2].pack("E*", buffer: b); b[1..].unpack("E*") == [v, v*2] }, ],
+  [ 'opt_newarray_send', <<-'},', ], # {
+    v = 7.89;
+    b = +"x";
+    class Array
+      alias _pack pack
+      def pack(s, buffer: nil, prefix: "y")
+        buffer ||= +"b"
+        buffer << prefix
+        _pack(s, buffer: buffer)
+      end
+    end
+    tests = []
+
+    ret = [v].pack("E*", prefix: "z")
+    tests << (ret[0..1] == "bz")
+    tests << (ret[2..].unpack("E*") == [v])
+
+    ret = [v].pack("E*")
+    tests << (ret[0..1] == "by")
+    tests << (ret[2..].unpack("E*") == [v])
+
+    [v, v*2, v*3].pack("E*", buffer: b)
+    tests << (b[0..1] == "xy")
+    tests << (b[2..].unpack("E*") == [v, v*2, v*3])
+
+    class Array
+      def pack(_fmt, buffer:) = buffer
+    end
+
+    b = nil
+    tests << [v].pack("E*", buffer: b).nil?
+
+    class Array
+      def pack(_fmt, **kw) = kw.empty?
+    end
+
+    tests << [v].pack("E*") == true
+
+    tests.all? or puts tests
+  },
 
   [ 'throw',        %q{ false.tap { break true } }, ],
   [ 'branchif',     %q{ x = nil;  x ||= true }, ],
@@ -352,7 +409,7 @@ tests = [
   [ 'opt_ge', %q{ +0.0.next_float >= 0.0 }, ],
   [ 'opt_ge', %q{              ?z >= ?a }, ],
 
-  [ 'opt_ltlt', %q{  '' << 'true' }, ],
+  [ 'opt_ltlt', %q{  +'' << 'true' }, ],
   [ 'opt_ltlt', %q{ ([] << 'true').join }, ],
   [ 'opt_ltlt', %q{ (1 << 31) == 2147483648 }, ],
 
@@ -361,7 +418,7 @@ tests = [
   [ 'opt_aref', %q{ 'true'[0] == ?t }, ],
   [ 'opt_aset', %q{ [][0] = true }, ],
   [ 'opt_aset', %q{ {}[0] = true }, ],
-  [ 'opt_aset', %q{ x = 'frue'; x[0] = 't'; x }, ],
+  [ 'opt_aset', %q{ x = +'frue'; x[0] = 't'; x }, ],
   [ 'opt_aset', <<-'},', ], # {
     # opt_aref / opt_aset mixup situation
     class X; def x; {}; end; end
@@ -369,11 +426,6 @@ tests = [
     x&.x[true] ||= true         # here
   },
 
-  [ 'opt_aref_with', %q{ { 'true' => true }['true'] }, ],
-  [ 'opt_aref_with', %q{ Struct.new(:nil).new['nil'].nil? }, ],
-  [ 'opt_aset_with', %q{ {}['true'] = true }, ],
-  [ 'opt_aset_with', %q{ Struct.new(:true).new['true'] = true }, ],
-
   [ 'opt_length',  %q{   'true'       .length == 4 }, ],
   [ 'opt_length',  %q{   :true        .length == 4 }, ],
   [ 'opt_length',  %q{ [ 'true' ]     .length == 1 }, ],
diff --git a/bootstraptest/test_io.rb b/bootstraptest/test_io.rb
index 666e5a011b..4081769a8c 100644
--- a/bootstraptest/test_io.rb
+++ b/bootstraptest/test_io.rb
@@ -85,13 +85,13 @@ assert_normal_exit %q{
   ARGF.set_encoding "foo"
 }
 
-/freebsd/ =~ RUBY_PLATFORM or
+/(freebsd|mswin)/ =~ RUBY_PLATFORM or
 10.times do
   assert_normal_exit %q{
     at_exit { p :foo }
 
     megacontent = "abc" * 12345678
-    #File.open("megasrc", "w") {|f| f << megacontent }
+    #File.write("megasrc", megacontent)
 
     t0 = Thread.main
     Thread.new { sleep 0.001 until t0.stop?; Process.kill(:INT, $$) }
diff --git a/bootstraptest/test_jump.rb b/bootstraptest/test_jump.rb
index d07c47a56d..8751343b1f 100644
--- a/bootstraptest/test_jump.rb
+++ b/bootstraptest/test_jump.rb
@@ -292,7 +292,7 @@ assert_equal "true", %q{
       end
     end
   end
-  s = "foo"
+  s = +"foo"
   s.return_eigenclass == class << s; self; end
 }, '[ruby-core:21379]'
 
diff --git a/bootstraptest/test_literal.rb b/bootstraptest/test_literal.rb
index a0d4ee08c6..39e6527027 100644
--- a/bootstraptest/test_literal.rb
+++ b/bootstraptest/test_literal.rb
@@ -70,6 +70,7 @@ if /wasi/ !~ target_platform
   assert_equal "foo\n",           %q(`echo foo`)
   assert_equal "foo\n",           %q(s = "foo"; `echo #{s}`)
 end
+assert_equal "ECHO FOO",        %q(def `(s) s.upcase; end; `echo foo`)
 
 # regexp
 assert_equal '',                '//.source'
@@ -116,16 +117,16 @@ assert_equal '1',               'a = [obj = Object.new]; a.size'
 assert_equal 'true',            'a = [obj = Object.new]; a[0] == obj'
 assert_equal '5',               'a = [1,2,3]; a[1] = 5; a[1]'
 assert_equal 'bar',             '[*:foo];:bar'
-assert_equal '[1, 2]',          'def nil.to_a; [2]; end; [1, *nil]'
-assert_equal '[1, 2]',          'def nil.to_a; [1, 2]; end; [*nil]'
-assert_equal '[0, 1, {2=>3}]',  '[0, *[1], 2=>3]', "[ruby-dev:31592]"
+assert_equal '[]',              'def nil.to_a; [1, 2]; end; [*nil]'
+assert_equal '[1]',             'def nil.to_a; [2]; end; [1, *nil]'
+assert_equal '[0, 1, {2 => 3}]', '[0, *[1], 2=>3]', "[ruby-dev:31592]"
 
 
 # hash
 assert_equal 'Hash',            '{}.class'
 assert_equal '{}',              '{}.inspect'
 assert_equal 'Hash',            '{1=>2}.class'
-assert_equal '{1=>2}',          '{1=>2}.inspect'
+assert_equal '{1 => 2}',        '{1=>2}.inspect'
 assert_equal '2',               'h = {1 => 2}; h[1]'
 assert_equal '0',               'h = {1 => 2}; h.delete(1); h.size'
 assert_equal '',                'h = {1 => 2}; h.delete(1); h[1]'
diff --git a/bootstraptest/test_literal_suffix.rb b/bootstraptest/test_literal_suffix.rb
index c36fa7078f..7a4d67d0fa 100644
--- a/bootstraptest/test_literal_suffix.rb
+++ b/bootstraptest/test_literal_suffix.rb
@@ -46,9 +46,9 @@ assert_equal '1',               '1rescue nil'
 assert_equal '10000000000000000001/10000000000000000000',
              '1.0000000000000000001r'
 
-assert_equal 'syntax error, unexpected local variable or method, expecting end-of-input',
-             %q{begin eval('1ir', nil, '', 0); rescue SyntaxError => e; e.message[/\A:(?:\d+:)? (.*)/, 1] end}
-assert_equal 'syntax error, unexpected local variable or method, expecting end-of-input',
-             %q{begin eval('1.2ir', nil, '', 0); rescue SyntaxError => e; e.message[/\A:(?:\d+:)? (.*)/, 1] end}
-assert_equal 'syntax error, unexpected local variable or method, expecting end-of-input',
-             %q{begin eval('1e1r', nil, '', 0); rescue SyntaxError => e; e.message[/\A:(?:\d+:)? (.*)/, 1] end}
+assert_equal 'unexpected local variable or method, expecting end-of-input',
+             %q{begin eval('1ir', nil, '', 0); rescue SyntaxError => e; e.message[/(?:\^~*|\A:(?:\d+:)? syntax error,) (.*)/, 1]; end}
+assert_equal 'unexpected local variable or method, expecting end-of-input',
+             %q{begin eval('1.2ir', nil, '', 0); rescue SyntaxError => e; e.message[/(?:\^~*|\A:(?:\d+:)? syntax error,) (.*)/, 1]; end}
+assert_equal 'unexpected local variable or method, expecting end-of-input',
+             %q{begin eval('1e1r', nil, '', 0); rescue SyntaxError => e; e.message[/(?:\^~*|\A:(?:\d+:)? syntax error,) (.*)/, 1]; end}
diff --git a/bootstraptest/test_load.rb b/bootstraptest/test_load.rb
index e63c93a8f4..fa8d31c098 100644
--- a/bootstraptest/test_load.rb
+++ b/bootstraptest/test_load.rb
@@ -1,9 +1,9 @@
 assert_equal 'ok', %q{
-  open("require-lock-test.rb", "w") {|f|
-    f.puts "sleep 0.1"
-    f.puts "module M"
-    f.puts "end"
-  }
+  File.write("require-lock-test.rb", <<-END)
+    sleep 0.1
+    module M
+    end
+  END
   $:.unshift Dir.pwd
   vs = (1..2).map {|i|
     Thread.start {
@@ -16,7 +16,7 @@ assert_equal 'ok', %q{
 
 assert_equal 'ok', %q{
   %w[a a/foo b].each {|d| Dir.mkdir(d)}
-  open("b/foo", "w") {|f| f.puts "$ok = :ok"}
+  File.write("b/foo", "$ok = :ok\n")
   $:.replace(%w[a b])
   begin
     load "foo"
diff --git a/bootstraptest/test_method.rb b/bootstraptest/test_method.rb
index 04c9eb2d11..78aab73485 100644
--- a/bootstraptest/test_method.rb
+++ b/bootstraptest/test_method.rb
@@ -340,24 +340,6 @@ assert_equal '1',       %q( class C; def m() 7 end; private :m end
 assert_equal '1',       %q( class C; def m() 1 end; private :m end
                             C.new.send(:m) )
 
-# with block
-assert_equal '[[:ok1, :foo], [:ok2, :foo, :bar]]',
-%q{
-  class C
-    def [](a)
-      $ary << [yield, a]
-    end
-    def []=(a, b)
-      $ary << [yield, a, b]
-    end
-  end
-
-  $ary = []
-  C.new[:foo, &lambda{:ok1}]
-  C.new[:foo, &lambda{:ok2}] = :bar
-  $ary
-}
-
 # with
 assert_equal '[:ok1, [:ok2, 11]]', %q{
   class C
@@ -404,7 +386,6 @@ $result
 
 # aset and splat
 assert_equal '4', %q{class Foo;def []=(a,b,c,d);end;end;Foo.new[1,*a=[2,3]]=4}
-assert_equal '4', %q{class Foo;def []=(a,b,c,d);end;end;def m(&blk)Foo.new[1,*a=[2,3],&blk]=4;end;m{}}
 
 # post test
 assert_equal %q{[1, 2, :o1, :o2, [], 3, 4, NilClass, nil, nil]}, %q{
@@ -1107,10 +1088,6 @@ assert_equal 'ok', %q{
     'ok'
   end
 }
-assert_equal 'ok', %q{
-  [0][0, &proc{}] += 21
-  'ok'
-}, '[ruby-core:30534]'
 
 # should not cache when splat
 assert_equal 'ok', %q{
@@ -1190,3 +1167,270 @@ assert_equal 'DC', %q{
   test2 o1, [], block
   $result.join
 }
+
+assert_equal 'ok', %q{
+  def foo
+    binding
+    ["ok"].first
+  end
+  foo
+  foo
+}, '[Bug #20178]'
+
+assert_equal 'ok', %q{
+  def bar(x); x; end
+  def foo(...); bar(...); end
+  foo('ok')
+}
+
+assert_equal 'ok', %q{
+  def bar(x); x; end
+  def foo(z, ...); bar(...); end
+  foo(1, 'ok')
+}
+
+assert_equal 'ok', %q{
+  def bar(x, y); x; end
+  def foo(...); bar("ok", ...); end
+  foo(1)
+}
+
+assert_equal 'ok', %q{
+  def bar(x); x; end
+  def foo(...); 1.times { return bar(...) }; end
+  foo("ok")
+}
+
+assert_equal 'ok', %q{
+  def bar(x); x; end
+  def foo(...); x = nil; 1.times { x = bar(...) }; x; end
+  foo("ok")
+}
+
+assert_equal 'ok', %q{
+  def bar(x); yield; end
+  def foo(...); bar(...); end
+  foo(1) { "ok" }
+}
+
+assert_equal 'ok', %q{
+  def baz(x); x; end
+  def bar(...); baz(...); end
+  def foo(...); bar(...); end
+  foo("ok")
+}
+
+assert_equal '[1, 2, 3, 4]', %q{
+  def baz(a, b, c, d); [a, b, c, d]; end
+  def bar(...); baz(1, ...); end
+  def foo(...); bar(2, ...); end
+  foo(3, 4)
+}
+
+assert_equal 'ok', %q{
+  class Foo; def self.foo(x); x; end; end
+  class Bar < Foo; def self.foo(...); super; end; end
+  Bar.foo('ok')
+}
+
+assert_equal 'ok', %q{
+  class Foo; def self.foo(x); x; end; end
+  class Bar < Foo; def self.foo(...); super(...); end; end
+  Bar.foo('ok')
+}
+
+assert_equal 'ok', %q{
+  class Foo; def self.foo(x, y); x + y; end; end
+  class Bar < Foo; def self.foo(...); super("o", ...); end; end
+  Bar.foo('k')
+}
+
+assert_equal 'ok', %q{
+  def bar(a); a; end
+  def foo(...); lambda { bar(...) }; end
+  foo("ok").call
+}
+
+assert_equal 'ok', %q{
+  class Foo; def self.foo(x, y); x + y; end; end
+  class Bar < Foo; def self.y(&b); b; end; def self.foo(...); y { super("o", ...) }; end; end
+  Bar.foo('k').call
+}
+
+assert_equal 'ok', %q{
+  def baz(n); n; end
+  def foo(...); bar = baz(...); lambda { lambda { bar } }; end
+  foo("ok").call.call
+}
+
+assert_equal 'ok', %q{
+  class A; def self.foo(...); new(...); end; attr_reader :b; def initialize(a, b:"ng"); @a = a; @b = b; end end
+  A.foo(1).b
+  A.foo(1, b: "ok").b
+}
+
+assert_equal 'ok', %q{
+  class A; def initialize; @a = ["ok"]; end; def first(...); @a.first(...); end; end
+  def call x; x.first; end
+  def call1 x; x.first(1); end
+  call(A.new)
+  call1(A.new).first
+}
+
+assert_equal 'ok', %q{
+  class A; def foo; yield("o"); end; end
+  class B < A; def foo(...); super { |x| yield(x + "k") }; end; end
+  B.new.foo { |x| x }
+}
+
+assert_equal "[1, 2, 3, 4]", %q{
+  def foo(*b) = b
+
+  def forward(...)
+    splat = [1,2,3]
+    foo(*splat, ...)
+  end
+
+  forward(4)
+}
+
+assert_equal "[1, 2, 3, 4]", %q{
+class A
+  def foo(*b) = b
+end
+
+class B < A
+  def foo(...)
+    splat = [1,2,3]
+    super(*splat, ...)
+  end
+end
+
+B.new.foo(4)
+}
+
+assert_equal 'ok', %q{
+  class A; attr_reader :iv; def initialize(...) = @iv = "ok"; end
+  A.new("foo", bar: []).iv
+}
+
+assert_equal 'ok', %q{
+  def foo(a, b) = a + b
+  def bar(...) = foo(...)
+  bar(1, 2)
+  bar(1, 2)
+  begin
+    bar(1, 2, 3)
+    "ng"
+  rescue ArgumentError
+    "ok"
+  end
+}
+
+assert_equal 'ok', %q{
+  class C
+    def foo(...) = :ok
+    def bar(...) = __send__(:foo, ...)
+  end
+
+  C.new.bar
+}
+
+assert_equal 'ok', %q{
+  class C
+    def method_missing(...) = :ok
+    def foo(...) = xyzzy(...)
+  end
+
+  C.new.foo
+}
+
+assert_equal 'ok', %q{
+  class C
+    def initialize(a)
+    end
+  end
+
+  def foo(...)
+    C.new(...)
+    :ok
+  end
+
+  foo(*["bar"])
+  foo("baz")
+}
+
+assert_equal 'ok', %q{
+  class C
+    def foo(b:)
+      b
+    end
+  end
+
+  def foo(...)
+    C.new.send(...)
+  end
+
+  foo(:foo, b: :ok)
+  foo(*["foo"], b: :ok)
+}
+
+assert_equal 'ok', %q{
+  Thing = Struct.new(:value)
+
+  Obj = Thing.new("ok")
+
+  def delegate(...)
+    Obj.value(...)
+  end
+
+  def no_args
+    delegate
+  end
+
+  def splat_args(*args)
+    delegate(*args)
+  end
+
+  no_args
+  splat_args
+}
+
+assert_equal 'ok', %q{
+  class A
+    private
+    def foo = "ng"
+  end
+
+  class B
+    def initialize(o)
+      @o = o
+    end
+
+    def foo(...) = @o.foo(...)
+    def internal_foo = foo
+  end
+
+  b = B.new(A.new)
+
+  begin
+    b.internal_foo
+  rescue NoMethodError
+    "ok"
+  end
+}
+
+assert_equal 'ok', <<~RUBY
+  def test(*, kw: false)
+    "ok"
+  end
+
+  test
+RUBY
+
+assert_equal '[1, 2, 3]', %q{
+  def target(*args) = args
+  def x = [1]
+  def forwarder(...) = target(*x, 2, ...)
+  forwarder(3).inspect
+}, '[Bug #21832] post-splat args before forwarding'
diff --git a/bootstraptest/test_ractor.rb b/bootstraptest/test_ractor.rb
index b29db7ab0e..e2a3e8dd5b 100644
--- a/bootstraptest/test_ractor.rb
+++ b/bootstraptest/test_ractor.rb
@@ -67,7 +67,7 @@ assert_equal "#<Ractor:#1 running>", %q{
 # Return id, loc, and status for no-name ractor
 assert_match /^#<Ractor:#([^ ]*?) .+:[0-9]+ terminated>$/, %q{
   r = Ractor.new { '' }
-  r.take
+  r.join
   sleep 0.1 until r.inspect =~ /terminated/
   r.inspect
 }
@@ -75,7 +75,7 @@ assert_match /^#<Ractor:#([^ ]*?) .+:[0-9]+ terminated>$/, %q{
 # Return id, name, loc, and status for named ractor
 assert_match /^#<Ractor:#([^ ]*?) Test Ractor .+:[0-9]+ terminated>$/, %q{
   r = Ractor.new(name: 'Test Ractor') { '' }
-  r.take
+  r.join
   sleep 0.1 until r.inspect =~ /terminated/
   r.inspect
 }
@@ -86,7 +86,7 @@ assert_equal 'ok', %q{
   r = Ractor.new do
     'ok'
   end
-  r.take
+  r.value
 }
 
 # Passed arguments to Ractor.new will be a block parameter
@@ -96,7 +96,7 @@ assert_equal 'ok', %q{
   r = Ractor.new 'ok' do |msg|
     msg
   end
-  r.take
+  r.value
 }
 
 # Pass multiple arguments to Ractor.new
@@ -105,7 +105,7 @@ assert_equal 'ok', %q{
   r =  Ractor.new 'ping', 'pong' do |msg, msg2|
     [msg, msg2]
   end
-  'ok' if r.take == ['ping', 'pong']
+  'ok' if r.value == ['ping', 'pong']
 }
 
 # Ractor#send passes an object with copy to a Ractor
@@ -115,65 +115,23 @@ assert_equal 'ok', %q{
     msg = Ractor.receive
   end
   r.send 'ok'
-  r.take
+  r.value
 }
 
 # Ractor#receive_if can filter the message
-assert_equal '[2, 3, 1]', %q{
-  r = Ractor.new Ractor.current do |main|
-    main << 1
-    main << 2
-    main << 3
-  end
-  a = []
-  a << Ractor.receive_if{|msg| msg == 2}
-  a << Ractor.receive_if{|msg| msg == 3}
-  a << Ractor.receive
-}
-
-# Ractor#receive_if with break
-assert_equal '[2, [1, :break], 3]', %q{
-  r = Ractor.new Ractor.current do |main|
-    main << 1
-    main << 2
-    main << 3
-  end
-
-  a = []
-  a << Ractor.receive_if{|msg| msg == 2}
-  a << Ractor.receive_if{|msg| break [msg, :break]}
-  a << Ractor.receive
-}
+assert_equal '[1, 2, 3]', %q{
+  ports = 3.times.map{Ractor::Port.new}
 
-# Ractor#receive_if can't be called recursively
-assert_equal '[[:e1, 1], [:e2, 2]]', %q{
-  r = Ractor.new Ractor.current do |main|
-    main << 1
-    main << 2
-    main << 3
+  r = Ractor.new ports do |ports|
+    ports[0] << 3
+    ports[1] << 1
+    ports[2] << 2
   end
-
   a = []
-
-  Ractor.receive_if do |msg|
-    begin
-      Ractor.receive
-    rescue Ractor::Error
-      a << [:e1, msg]
-    end
-    true # delete 1 from queue
-  end
-
-  Ractor.receive_if do |msg|
-    begin
-      Ractor.receive_if{}
-    rescue Ractor::Error
-      a << [:e2, msg]
-    end
-    true # delete 2 from queue
-  end
-
-  a #
+  a << ports[1].receive # 1
+  a << ports[2].receive # 2
+  a << ports[0].receive # 3
+  a
 }
 
 # dtoa race condition
@@ -184,73 +142,145 @@ assert_equal '[:ok, :ok, :ok]', %q{
       10_000.times{ rand.to_s }
       :ok
     }
-  }.map(&:take)
+  }.map(&:value)
+}
+
+assert_equal "42", %q{
+  a = 42
+  Ractor.shareable_lambda{ a }.call
 }
 
-# Ractor.make_shareable issue for locals in proc [Bug #18023]
+# Ractor.shareable_proc issue for locals in proc [Bug #18023]
 assert_equal '[:a, :b, :c, :d, :e]', %q{
   v1, v2, v3, v4, v5 = :a, :b, :c, :d, :e
-  closure = Ractor.current.instance_eval{ Proc.new { [v1, v2, v3, v4, v5] } }
+  closure = Proc.new { [v1, v2, v3, v4, v5] }
+  Ractor.shareable_proc(&closure).call
+}
+
+# Ractor.shareable_proc makes a copy of given Proc
+assert_equal '[true, true]', %q{
+  pr1 = Proc.new do
+    self
+  end
+  pr2 = Ractor.shareable_proc(&pr1)
 
-  Ractor.make_shareable(closure).call
+  [pr1.call == self, pr2.call == nil]
 }
 
-# Ractor.make_shareable issue for locals in proc [Bug #18023]
-assert_equal '[:a, :b, :c, :d, :e, :f, :g]', %q{
-  a = :a
-  closure = Ractor.current.instance_eval do
-    -> {
-      b, c, d = :b, :c, :d
-      -> {
-        e, f, g = :e, :f, :g
-        -> { [a, b, c, d, e, f, g] }
-      }.call
-    }.call
+# Ractor.shareable_proc keeps the original Proc intact
+assert_equal '[SyntaxError, [Object, 43, 43], Binding]', %q{
+  a = 42
+  pr1 = Proc.new do
+    [self.class, eval("a"), binding.local_variable_get(:a)]
   end
+  a += 1
+  pr2 = Ractor.shareable_proc(&pr1)
 
-  Ractor.make_shareable(closure).call
+  r = []
+  begin
+    pr2.call
+  rescue SyntaxError
+    r << SyntaxError
+  end
+
+  r << pr1.call << pr1.binding.class
 }
 
-# Now autoload in non-main Ractor is not supported
-assert_equal 'ok', %q{
-  autoload :Foo, 'foo.rb'
-  r = Ractor.new do
-    p Foo
-  rescue Ractor::UnsafeError
-    :ok
+# Ractor.make_shareable mutates the original Proc
+# This is the current behavior, it's currently considered safe enough
+# because in most cases it would raise anyway due to not-shared self or not-shared captured variable value
+assert_equal '[[42, 42], Binding, true, SyntaxError, "Can\'t create Binding from isolated Proc"]', %q{
+  a = 42
+  pr1 = nil.instance_exec do
+    Proc.new do
+      [eval("a"), binding.local_variable_get(:a)]
+    end
+  end
+
+  r = [pr1.call, pr1.binding.class]
+
+  pr2 = Ractor.make_shareable(pr1)
+  r << pr1.equal?(pr2)
+
+  begin
+    pr1.call
+  rescue SyntaxError
+    r << SyntaxError
+  end
+
+  begin
+    r << pr1.binding
+  rescue ArgumentError
+    r << $!.message
+  end
+
+  r
+}
+
+# Ractor::IsolationError cases
+assert_equal '3', %q{
+  ok = 0
+
+  begin
+    a = 1
+    Ractor.shareable_proc{a}
+    a = 2
+  rescue Ractor::IsolationError => e
+    ok += 1
+  end
+
+  begin
+    cond = false
+    b = 1
+    b = 2 if cond
+    Ractor.shareable_proc{b}
+  rescue Ractor::IsolationError => e
+    ok += 1
+  end
+
+  begin
+    1.times{|i|
+      i = 2
+      Ractor.shareable_proc{i}
+    }
+  rescue Ractor::IsolationError => e
+    ok += 1
   end
-  r.take
 }
 
 ###
 ###
 # Ractor still has several memory corruption so skip huge number of tests
-if ENV['GITHUB_WORKFLOW'] &&
-   ENV['GITHUB_WORKFLOW'] == 'Compilations'
+if ENV['GITHUB_WORKFLOW'] == 'Compilations'
    # ignore the follow
 else
 
-# Ractor.select(*ractors) receives a values from a ractors.
-# It is similar to select(2) and Go's select syntax.
-# The return value is [ch, received_value]
+# Ractor.select with a Ractor argument
 assert_equal 'ok', %q{
   # select 1
   r1 = Ractor.new{'r1'}
-  r, obj = Ractor.select(r1)
-  'ok' if r == r1 and obj == 'r1'
+  port, obj = Ractor.select(r1)
+  if port == r1 and obj == 'r1'
+    'ok'
+  else
+    # failed
+    [port, obj].inspect
+  end
 }
 
 # Ractor.select from two ractors.
 assert_equal '["r1", "r2"]', %q{
   # select 2
-  r1 = Ractor.new{'r1'}
-  r2 = Ractor.new{'r2'}
-  rs = [r1, r2]
+  p1 = Ractor::Port.new
+  p2 = Ractor::Port.new
+  r1 = Ractor.new(p1){|p1| p1 << 'r1'}
+  r2 = Ractor.new(p2){|p2| p2 << 'r2'}
+  ps = [p1, p2]
   as = []
-  r, obj = Ractor.select(*rs)
-  rs.delete(r)
+  port, obj = Ractor.select(*ps)
+  ps.delete(port)
   as << obj
-  r, obj = Ractor.select(*rs)
+  port, obj = Ractor.select(*ps)
   as << obj
   as.sort #=> ["r1", "r2"]
 }
@@ -283,11 +313,10 @@ assert_equal 30.times.map { 'ok' }.to_s, %q{
   30.times.map{|i|
     test i
   }
-} unless ENV['RUN_OPTS'] =~ /--jit-min-calls=5/ || # This always fails with --jit-wait --jit-min-calls=5
-  (ENV.key?('TRAVIS') && ENV['TRAVIS_CPU_ARCH'] == 'arm64') # https://bugs.ruby-lang.org/issues/17878
+} unless (ENV.key?('TRAVIS') && ENV['TRAVIS_CPU_ARCH'] == 'arm64') # https://bugs.ruby-lang.org/issues/17878
 
 # Exception for empty select
-assert_match /specify at least one ractor/, %q{
+assert_match /specify at least one Ractor::Port or Ractor/, %q{
   begin
     Ractor.select
   rescue ArgumentError => e
@@ -295,30 +324,12 @@ assert_match /specify at least one ractor/, %q{
   end
 }
 
-# Outgoing port of a ractor will be closed when the Ractor is terminated.
-assert_equal 'ok', %q{
-  r = Ractor.new do
-    'finish'
-  end
-
-  r.take
-  sleep 0.1 until r.inspect =~ /terminated/
-
-  begin
-    o = r.take
-  rescue Ractor::ClosedError
-    'ok'
-  else
-    "ng: #{o}"
-  end
-}
-
 # Raise Ractor::ClosedError when try to send into a terminated ractor
 assert_equal 'ok', %q{
   r = Ractor.new do
   end
 
-  r.take # closed
+  r.join # closed
   sleep 0.1 until r.inspect =~ /terminated/
 
   begin
@@ -330,47 +341,16 @@ assert_equal 'ok', %q{
   end
 }
 
-# Raise Ractor::ClosedError when try to send into a closed actor
-assert_equal 'ok', %q{
-  r = Ractor.new { Ractor.receive }
-  r.close_incoming
-
-  begin
-    r.send(1)
-  rescue Ractor::ClosedError
-    'ok'
-  else
-    'ng'
-  end
-}
-
-# Raise Ractor::ClosedError when try to take from closed actor
-assert_equal 'ok', %q{
-  r = Ractor.new do
-    Ractor.yield 1
-    Ractor.receive
-  end
-
-  r.close_outgoing
-  begin
-    r.take
-  rescue Ractor::ClosedError
-    'ok'
-  else
-    'ng'
-  end
-}
-
-# Can mix with Thread#interrupt and Ractor#take [Bug #17366]
+# Can mix with Thread#interrupt and Ractor#join [Bug #17366]
 assert_equal 'err', %q{
-  Ractor.new{
+  Ractor.new do
     t = Thread.current
     begin
       Thread.new{ t.raise "err" }.join
     rescue => e
       e.message
     end
-  }.take
+  end.value
 }
 
 # Killed Ractor's thread yields nil
@@ -378,34 +358,18 @@ assert_equal 'nil', %q{
   Ractor.new{
     t = Thread.current
     Thread.new{ t.kill }.join
-  }.take.inspect #=> nil
+  }.value.inspect #=> nil
 }
 
-# Ractor.yield raises Ractor::ClosedError when outgoing port is closed.
+# Raise Ractor::ClosedError when try to send into a ractor with closed default port
 assert_equal 'ok', %q{
-  r = Ractor.new Ractor.current do |main|
+  r = Ractor.new {
+    Ractor.current.close
+    Ractor.main << :ok
     Ractor.receive
-    main << true
-    Ractor.yield 1
-  end
-
-  r.close_outgoing
-  r << true
-  Ractor.receive
-
-  begin
-    r.take
-  rescue Ractor::ClosedError
-    'ok'
-  else
-    'ng'
-  end
-}
+  }
 
-# Raise Ractor::ClosedError when try to send into a ractor with closed incoming port
-assert_equal 'ok', %q{
-  r = Ractor.new { Ractor.receive }
-  r.close_incoming
+  Ractor.receive # wait for ok
 
   begin
     r.send(1)
@@ -416,148 +380,82 @@ assert_equal 'ok', %q{
   end
 }
 
-# A ractor with closed incoming port still can send messages out
-assert_equal '[1, 2]', %q{
-  r = Ractor.new do
-    Ractor.yield 1
-    2
-  end
-  r.close_incoming
-
-  [r.take, r.take]
-}
-
-# Raise Ractor::ClosedError when try to take from a ractor with closed outgoing port
-assert_equal 'ok', %q{
-  r = Ractor.new do
-    Ractor.yield 1
-    Ractor.receive
-  end
-
-  sleep 0.01 # wait for Ractor.yield in r
-  r.close_outgoing
-  begin
-    r.take
-  rescue Ractor::ClosedError
-    'ok'
-  else
-    'ng'
-  end
-}
-
-# A ractor with closed outgoing port still can receive messages from incoming port
-assert_equal 'ok', %q{
-  r = Ractor.new do
-    Ractor.receive
-  end
-
-  r.close_outgoing
-  begin
-    r.send(1)
-  rescue Ractor::ClosedError
-    'ng'
-  else
-    'ok'
-  end
-}
-
 # Ractor.main returns main ractor
 assert_equal 'true', %q{
   Ractor.new{
     Ractor.main
-  }.take == Ractor.current
+  }.value == Ractor.current
 }
 
 # a ractor with closed outgoing port should terminate
 assert_equal 'ok', %q{
   Ractor.new do
-    close_outgoing
+    Ractor.current.close
   end
 
   true until Ractor.count == 1
   :ok
 }
 
-# multiple Ractors can receive (wait) from one Ractor
-assert_equal '[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]', %q{
-  pipe = Ractor.new do
-    loop do
-      Ractor.yield Ractor.receive
-    end
+# an exception in a Ractor main thread will be re-raised at Ractor#receive
+assert_equal '[RuntimeError, "ok", true]', %q{
+  r = Ractor.new do
+    raise 'ok' # exception will be transferred receiver
+  end
+  begin
+    r.join
+  rescue Ractor::RemoteError => e
+    [e.cause.class,   #=> RuntimeError
+     e.cause.message, #=> 'ok'
+     e.ractor == r]   #=> true
   end
-
-  RN = 10
-  rs = RN.times.map{|i|
-    Ractor.new pipe, i do |pipe, i|
-      msg = pipe.take
-      msg # ping-pong
-    end
-  }
-  RN.times{|i|
-    pipe << i
-  }
-  RN.times.map{
-    r, n = Ractor.select(*rs)
-    rs.delete r
-    n
-  }.sort
 }
 
-# Ractor.select also support multiple take, receive and yield
-assert_equal '[true, true, true]', %q{
-  RN = 10
-  CR = Ractor.current
-
-  rs = (1..RN).map{
-    Ractor.new do
-      CR.send 'send' + CR.take #=> 'sendyield'
-      'take'
-    end
-  }
-  received = []
-  take = []
-  yielded = []
-  until rs.empty?
-    r, v = Ractor.select(CR, *rs, yield_value: 'yield')
-    case r
-    when :receive
-      received << v
-    when :yield
-      yielded << v
-    else
-      take << v
-      rs.delete r
-    end
+# an exception in a Ractor will be re-raised at Ractor#value
+assert_equal '[RuntimeError, "ok", true]', %q{
+  r = Ractor.new do
+    raise 'ok' # exception will be transferred receiver
+  end
+  begin
+    r.value
+  rescue Ractor::RemoteError => e
+    [e.cause.class,   #=> RuntimeError
+     e.cause.message, #=> 'ok'
+     e.ractor == r]   #=> true
   end
-  [received.all?('sendyield'), yielded.all?(nil), take.all?('take')]
 }
 
-# multiple Ractors can send to one Ractor
-assert_equal '[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]', %q{
-  pipe = Ractor.new do
-    loop do
-      Ractor.yield Ractor.receive
+# an exception in a Ractor non-main thread will not be re-raised at Ractor#receive
+assert_equal 'ok', %q{
+  r = Ractor.new do
+    Thread.new do
+      raise 'ng'
     end
+    sleep 0.1
+    'ok'
   end
-
-  RN = 10
-  RN.times.map{|i|
-    Ractor.new pipe, i do |pipe, i|
-      pipe << i
-    end
-  }
-  RN.times.map{
-    pipe.take
-  }.sort
+  r.value
 }
 
-# an exception in a Ractor will be re-raised at Ractor#receive
-assert_equal '[RuntimeError, "ok", true]', %q{
-  r = Ractor.new do
-    raise 'ok' # exception will be transferred receiver
+# SystemExit from a Ractor is re-raised
+# [Bug #21505]
+assert_equal '[SystemExit, "exit", true]', %q{
+  r = Ractor.new { exit }
+  begin
+    r.value
+  rescue Ractor::RemoteError => e
+    [e.cause.class,   #=> RuntimeError
+     e.cause.message, #=> 'ok'
+     e.ractor == r]   #=> true
   end
+}
+
+# SystemExit from a Thread inside a Ractor is re-raised
+# [Bug #21505]
+assert_equal '[SystemExit, "exit", true]', %q{
+  r = Ractor.new { Thread.new { exit }.join }
   begin
-    r.take
+    r.value
   rescue Ractor::RemoteError => e
     [e.cause.class,   #=> RuntimeError
      e.cause.message, #=> 'ok'
@@ -566,7 +464,7 @@ assert_equal '[RuntimeError, "ok", true]', %q{
 }
 
 # threads in a ractor will killed
-assert_equal '{:ok=>3}', %q{
+assert_equal '{ok: 3}', %q{
   Ractor.new Ractor.current do |main|
     q = Thread::Queue.new
     Thread.new do
@@ -596,7 +494,7 @@ assert_equal '{:ok=>3}', %q{
   end
 
   3.times.map{Ractor.receive}.tally
-}
+} unless yjit_enabled? # YJIT: `[BUG] Bus Error at 0x000000010b7002d0` in jit_exec()
 
 # unshareable object are copied
 assert_equal 'false', %q{
@@ -605,7 +503,7 @@ assert_equal 'false', %q{
     msg.object_id
   end
 
-  obj.object_id == r.take
+  obj.object_id == r.value
 }
 
 # To copy the object, now Marshal#dump is used
@@ -623,11 +521,12 @@ assert_equal "allocator undefined for Thread", %q{
 }
 
 # send shareable and unshareable objects
-assert_equal "ok", %q{
-  echo_ractor = Ractor.new do
+assert_equal "ok", <<~'RUBY', frozen_string_literal: false
+  port = Ractor::Port.new
+  echo_ractor = Ractor.new port do |port|
     loop do
       v = Ractor.receive
-      Ractor.yield v
+      port << v
     end
   end
 
@@ -675,13 +574,13 @@ assert_equal "ok", %q{
 
   shareable_objects.map{|o|
     echo_ractor << o
-    o2 = echo_ractor.take
+    o2 = port.receive
     results << "#{o} is copied" unless o.object_id == o2.object_id
   }
 
   unshareable_objects.map{|o|
     echo_ractor << o
-    o2 = echo_ractor.take
+    o2 = port.receive
     results << "#{o.inspect} is not copied" if o.object_id == o2.object_id
   }
 
@@ -690,10 +589,10 @@ assert_equal "ok", %q{
   else
     results.inspect
   end
-}
+RUBY
 
 # frozen Objects are shareable
-assert_equal [false, true, false].inspect, %q{
+assert_equal [false, true, false].inspect, <<~'RUBY', frozen_string_literal: false
   class C
     def initialize freeze
       @a = 1
@@ -707,7 +606,7 @@ assert_equal [false, true, false].inspect, %q{
   def check obj1
     obj2 = Ractor.new obj1 do |obj|
       obj
-    end.take
+    end.value
 
     obj1.object_id == obj2.object_id
   end
@@ -716,11 +615,11 @@ assert_equal [false, true, false].inspect, %q{
   results << check(C.new(true))         # false
   results << check(C.new(true).freeze)  # true
   results << check(C.new(false).freeze) # false
-}
+RUBY
 
 # move example2: String
 # touching moved object causes an error
-assert_equal 'hello world', %q{
+assert_equal 'hello world', <<~'RUBY', frozen_string_literal: false
   # move
   r = Ractor.new do
     obj = Ractor.receive
@@ -729,7 +628,7 @@ assert_equal 'hello world', %q{
 
   str = 'hello'
   r.send str, move: true
-  modified = r.take
+  modified = r.value
 
   begin
     str << ' exception' # raise Ractor::MovedError
@@ -738,7 +637,7 @@ assert_equal 'hello world', %q{
   else
     raise 'unreachable'
   end
-}
+RUBY
 
 # move example2: Array
 assert_equal '[0, 1]', %q{
@@ -749,7 +648,7 @@ assert_equal '[0, 1]', %q{
 
   a1 = [0]
   r.send a1, move: true
-  a2 = r.take
+  a2 = r.value
   begin
     a1 << 2 # raise Ractor::MovedError
   rescue Ractor::MovedError
@@ -757,70 +656,39 @@ assert_equal '[0, 1]', %q{
   end
 }
 
-# move with yield
-assert_equal 'hello', %q{
-  r = Ractor.new do
-    Thread.current.report_on_exception = false
-    obj = 'hello'
-    Ractor.yield obj, move: true
-    obj << 'world'
-  end
-
-  str = r.take
-  begin
-    r.take
-  rescue Ractor::RemoteError
-    str #=> "hello"
-  end
-}
-
-# yield/move should not make moved object when the yield is not succeeded
-assert_equal '"str"', %q{
-  R = Ractor.new{}
-  M = Ractor.current
-  r = Ractor.new do
-    s = 'str'
-    selected_r, v = Ractor.select R, yield_value: s, move: true
-    raise if selected_r != R # taken from R
-    M.send s.inspect # s should not be a moved object
-  end
-
-  Ractor.receive
-}
-
-# yield/move can fail
-assert_equal "allocator undefined for Thread", %q{
+# unshareable frozen objects should still be frozen in new ractor after move
+assert_equal 'true', %q{
   r = Ractor.new do
-    obj = Thread.new{}
-    Ractor.yield obj
-  rescue => e
-    e.message
+    obj = receive
+    { frozen: obj.frozen? }
   end
-  r.take
+  obj = [Object.new].freeze
+  r.send(obj, move: true)
+  r.value[:frozen]
 }
 
-# Access to global-variables are prohibited
-assert_equal 'can not access global variables $gv from non-main Ractors', %q{
+# Access to global-variables are prohibited (read)
+assert_equal 'can not access global variable $gv from non-main Ractor', %q{
   $gv = 1
   r = Ractor.new do
     $gv
   end
 
   begin
-    r.take
+    r.join
   rescue Ractor::RemoteError => e
     e.cause.message
   end
 }
 
-# Access to global-variables are prohibited
-assert_equal 'can not access global variables $gv from non-main Ractors', %q{
+# Access to global-variables are prohibited (write)
+assert_equal 'can not access global variable $gv from non-main Ractor', %q{
   r = Ractor.new do
     $gv = 1
   end
 
   begin
-    r.take
+    r.join
   rescue Ractor::RemoteError => e
     e.cause.message
   end
@@ -834,7 +702,7 @@ assert_equal 'ok', %q{
     }
   end
 
-  [$stdin, $stdout, $stderr].zip(r.take){|io, (oid, fno)|
+  [$stdin, $stdout, $stderr].zip(r.value){|io, (oid, fno)|
     raise "should not be different object" if io.object_id == oid
     raise "fd should be same" unless io.fileno == fno
   }
@@ -850,7 +718,7 @@ assert_equal 'ok', %q{
     'ok'
   end
 
-  r.take
+  r.value
 }
 
 # $DEBUG, $VERBOSE are Ractor local
@@ -908,7 +776,7 @@ assert_equal 'true', %q{
 
   h = Ractor.new do
     ractor_local_globals
-  end.take
+  end.value
   ractor_local_globals == h #=> true
 }
 
@@ -917,7 +785,8 @@ assert_equal 'false', %q{
   r = Ractor.new do
     self.object_id
   end
-  r.take == self.object_id #=> false
+  ret = r.value
+  ret == self.object_id
 }
 
 # self is a Ractor instance
@@ -925,7 +794,12 @@ assert_equal 'true', %q{
   r = Ractor.new do
     self.object_id
   end
-  r.object_id == r.take #=> true
+  ret = r.value
+  if r.object_id == ret #=> true
+    true
+  else
+    raise [ret, r.object_id].inspect
+  end
 }
 
 # given block Proc will be isolated, so can not access outer variables.
@@ -940,8 +814,39 @@ assert_equal 'ArgumentError', %q{
   end
 }
 
+# eval with outer locals in a Ractor raises SyntaxError
+# [Bug #21522]
+assert_equal 'SyntaxError', %q{
+  outer = 42
+  r = Ractor.new do
+    eval("outer")
+  end
+  begin
+    r.value
+  rescue Ractor::RemoteError => e
+    e.cause.class
+  end
+}
+
+# eval of an undefined name in a Ractor raises NameError
+assert_equal 'NameError', %q{
+  r = Ractor.new do
+    eval("totally_undefined_name")
+  end
+  begin
+    r.value
+  rescue Ractor::RemoteError => e
+    e.cause.class
+  end
+}
+
+# eval of a local defined inside the Ractor works
+assert_equal '99', %q{
+  Ractor.new { inner = 99; eval("inner").to_s }.value
+}
+
 # ivar in shareable-objects are not allowed to access from non-main Ractor
-assert_equal "can not get unshareable values from instance variables of classes/modules from non-main Ractors", %q{
+assert_equal "can not get unshareable values from instance variables of classes/modules from non-main Ractors (@iv from C)", <<~'RUBY', frozen_string_literal: false
   class C
     @iv = 'str'
   end
@@ -952,13 +857,12 @@ assert_equal "can not get unshareable values from instance variables of classes/
     end
   end
 
-
   begin
-    r.take
+    r.value
   rescue Ractor::RemoteError => e
     e.cause.message
   end
-}
+RUBY
 
 # ivar in shareable-objects are not allowed to access from non-main Ractor
 assert_equal 'can not access instance variables of shareable objects from non-main Ractors', %q{
@@ -970,7 +874,7 @@ assert_equal 'can not access instance variables of shareable objects from non-ma
   end
 
   begin
-    r.take
+    r.value
   rescue Ractor::RemoteError => e
     e.cause.message
   end
@@ -996,7 +900,7 @@ assert_equal 'can not access instance variables of shareable objects from non-ma
   end
 
   begin
-    r.take
+    r.value
   rescue Ractor::RemoteError => e
     e.cause.message
   end
@@ -1017,7 +921,7 @@ assert_equal 'can not access instance variables of shareable objects from non-ma
   end
 
   begin
-    r.take
+    r.value
   rescue Ractor::RemoteError => e
     e.cause.message
   end
@@ -1031,7 +935,7 @@ assert_equal '11', %q{
 
     Ractor.new obj do |obj|
       obj.instance_variable_get('@a')
-    end.take.to_s
+    end.value.to_s
   }.join
 }
 
@@ -1057,33 +961,68 @@ assert_equal '333', %q{
     def self.fstr = @fstr
   end
 
-  a = Ractor.new{ C.int }.take
+  a = Ractor.new{ C.int }.value
   b = Ractor.new do
     C.str.to_i
   rescue Ractor::IsolationError
     10
-  end.take
+  end.value
   c = Ractor.new do
     C.fstr.to_i
-  end.take
+  end.value
 
-  d = Ractor.new{ M.int }.take
+  d = Ractor.new{ M.int }.value
   e = Ractor.new do
     M.str.to_i
   rescue Ractor::IsolationError
     20
-  end.take
+  end.value
   f = Ractor.new do
     M.fstr.to_i
-  end.take
+  end.value
 
 
   # 1 + 10 + 100 + 2 + 20 + 200
   a + b + c + d + e + f
 }
 
+assert_equal '["instance-variable", "instance-variable", nil]', %q{
+  class C
+    @iv1 = ""
+    @iv2 = 42
+    def self.iv1 = defined?(@iv1) # "instance-variable"
+    def self.iv2 = defined?(@iv2) # "instance-variable"
+    def self.iv3 = defined?(@iv3) # nil
+  end
+
+  Ractor.new{
+    [C.iv1, C.iv2, C.iv3]
+  }.value
+}
+
+# moved objects have their shape properly set to original object's shape
+assert_equal '1234', %q{
+  class Obj
+    attr_accessor :a, :b, :c, :d
+    def initialize
+      @a = 1
+      @b = 2
+      @c = 3
+    end
+  end
+  r = Ractor.new do
+    obj = receive
+    obj.d = 4
+    [obj.a, obj.b, obj.c, obj.d]
+  end
+  obj = Obj.new
+  r.send(obj, move: true)
+  values = r.value
+  values.join
+}
+
 # cvar in shareable-objects are not allowed to access from non-main Ractor
-assert_equal 'can not access class variables from non-main Ractors', %q{
+assert_equal 'can not access class variables from non-main Ractors (@@cv from C)', %q{
   class C
     @@cv = 'str'
   end
@@ -1095,14 +1034,14 @@ assert_equal 'can not access class variables from non-main Ractors', %q{
   end
 
   begin
-    r.take
+    r.join
   rescue Ractor::RemoteError => e
     e.cause.message
   end
 }
 
 # also cached cvar in shareable-objects are not allowed to access from non-main Ractor
-assert_equal 'can not access class variables from non-main Ractors', %q{
+assert_equal 'can not access class variables from non-main Ractors (@@cv from C)', %q{
   class C
     @@cv = 'str'
     def self.cv
@@ -1117,14 +1056,14 @@ assert_equal 'can not access class variables from non-main Ractors', %q{
   end
 
   begin
-    r.take
+    r.join
   rescue Ractor::RemoteError => e
     e.cause.message
   end
 }
 
 # Getting non-shareable objects via constants by other Ractors is not allowed
-assert_equal 'can not access non-shareable objects in constant C::CONST by non-main Ractor.', %q{
+assert_equal 'can not access non-shareable objects in constant C::CONST by non-main Ractor.', <<~'RUBY', frozen_string_literal: false
   class C
     CONST = 'str'
   end
@@ -1132,44 +1071,58 @@ assert_equal 'can not access non-shareable objects in constant C::CONST by non-m
     C::CONST
   end
   begin
-    r.take
+    r.join
   rescue Ractor::RemoteError => e
     e.cause.message
   end
-}
+  RUBY
 
-# Constant cache should care about non-sharable constants
-assert_equal "can not access non-shareable objects in constant Object::STR by non-main Ractor.", %q{
+# Constant cache should care about non-shareable constants
+assert_equal "can not access non-shareable objects in constant Object::STR by non-main Ractor.", <<~'RUBY', frozen_string_literal: false
   STR = "hello"
   def str; STR; end
   s = str() # fill const cache
   begin
-    Ractor.new{ str() }.take
+    Ractor.new{ str() }.join
   rescue Ractor::RemoteError => e
     e.cause.message
   end
-}
+RUBY
+
+# The correct constant path shall be reported
+assert_equal "can not access non-shareable objects in constant Object::STR by non-main Ractor.", <<~'RUBY', frozen_string_literal: false
+  STR = "hello"
+  module M
+    def self.str; STR; end
+  end
+
+  begin
+    Ractor.new{ M.str }.join
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+RUBY
 
 # Setting non-shareable objects into constants by other Ractors is not allowed
-assert_equal 'can not set constants with non-shareable objects by non-main Ractors', %q{
+assert_equal 'can not set constants with non-shareable objects by non-main Ractors', <<~'RUBY', frozen_string_literal: false
   class C
   end
   r = Ractor.new do
     C::CONST = 'str'
   end
   begin
-    r.take
+    r.join
   rescue Ractor::RemoteError => e
     e.cause.message
   end
-}
+RUBY
 
 # define_method is not allowed
 assert_equal "defined with an un-shareable Proc in a different Ractor", %q{
   str = "foo"
   define_method(:buggy){|i| str << "#{i}"}
   begin
-    Ractor.new{buggy(10)}.take
+    Ractor.new{buggy(10)}.join
   rescue => e
     e.cause.message
   end
@@ -1180,7 +1133,7 @@ assert_equal '[1000, 3]', %q{
   A = Array.new(1000).freeze # [nil, ...]
   H = {a: 1, b: 2, c: 3}.freeze
 
-  Ractor.new{ [A.size, H.size] }.take
+  Ractor.new{ [A.size, H.size] }.value
 }
 
 # Ractor.count
@@ -1190,15 +1143,15 @@ assert_equal '[1, 4, 3, 2, 1]', %q{
   ractors = (1..3).map { Ractor.new { Ractor.receive } }
   counts << Ractor.count
 
-  ractors[0].send('End 0').take
+  ractors[0].send('End 0').join
   sleep 0.1 until ractors[0].inspect =~ /terminated/
   counts << Ractor.count
 
-  ractors[1].send('End 1').take
+  ractors[1].send('End 1').join
   sleep 0.1 until ractors[1].inspect =~ /terminated/
   counts << Ractor.count
 
-  ractors[2].send('End 2').take
+  ractors[2].send('End 2').join
   sleep 0.1 until ractors[2].inspect =~ /terminated/
   counts << Ractor.count
 
@@ -1211,11 +1164,11 @@ assert_equal '0', %q{
     n = 0
     ObjectSpace.each_object{|o| n += 1 unless Ractor.shareable?(o)}
     n
-  }.take
+  }.value
 }
 
 # ObjectSpace._id2ref can not handle unshareable objects with Ractors
-assert_equal 'ok', %q{
+assert_equal 'ok', <<~'RUBY', frozen_string_literal: false
   s = 'hello'
 
   Ractor.new s.object_id do |id ;s|
@@ -1224,11 +1177,29 @@ assert_equal 'ok', %q{
     rescue => e
       :ok
     end
-  end.take
-}
+  end.value
+RUBY
+
+# Inserting into the id2ref table should be Ractor-safe
+assert_equal 'ok', <<~'RUBY'
+  # Force all calls to Kernel#object_id to insert into the id2ref table
+  obj = Object.new
+  ObjectSpace._id2ref(obj.object_id) rescue nil
+
+  10.times.map do
+    Ractor.new do
+      10_000.times do
+        a = Object.new
+        a.object_id
+      end
+    end
+  end.map(&:value)
+
+  :ok
+RUBY
 
 # Ractor.make_shareable(obj)
-assert_equal 'true', %q{
+assert_equal 'true', <<~'RUBY', frozen_string_literal: false
   class C
     def initialize
       @a = 'foo'
@@ -1299,7 +1270,7 @@ assert_equal 'true', %q{
   }
 
   Ractor.shareable?(a)
-}
+RUBY
 
 # Ractor.make_shareable(obj) doesn't freeze shareable objects
 assert_equal 'true', %q{
@@ -1308,19 +1279,42 @@ assert_equal 'true', %q{
   [a.frozen?, a[0].frozen?] == [true, false]
 }
 
-# Ractor.make_shareable(a_proc) makes a proc shareable.
-assert_equal 'true', %q{
-  a = [1, [2, 3], {a: "4"}]
+# Ractor.make_shareable(a_proc) requires a shareable receiver
+assert_equal '[:ok, "Proc\'s self is not shareable:"]', %q{
+  pr1 = nil.instance_exec { Proc.new{} }
+  pr2 = Proc.new{}
 
-  pr = Ractor.current.instance_eval do
-    Proc.new do
-      a
+  [pr1, pr2].map do |pr|
+    begin
+      Ractor.make_shareable(pr)
+    rescue Ractor::Error => e
+      e.message[/^.+?:/]
+    else
+      :ok
     end
   end
+}
+
+# Ractor.make_shareable(Method/UnboundMethod)
+assert_equal 'true', %q{
+  # raise because receiver is unshareable
+  begin
+    _m0 = Ractor.make_shareable(self.method(:__id__))
+  rescue => e
+    raise e unless e.message =~ /can not make shareable object/
+  else
+    raise "no error"
+  end
 
-  Ractor.make_shareable(a) # referred value should be shareable
-  Ractor.make_shareable(pr)
-  Ractor.shareable?(pr)
+  # Method with shareable receiver
+  M1 = Ractor.make_shareable(Object.method(:__id__))
+
+  # UnboundMethod
+  M2 = Ractor.make_shareable(Object.instance_method(:__id__))
+
+  Ractor.new do
+    Object.__id__ == M1.call && M1.call == M2.bind_call(Object)
+  end.value
 }
 
 # Ractor.shareable?(recursive_objects)
@@ -1355,29 +1349,10 @@ assert_equal '[C, M]', %q{
 assert_equal '1', %q{
   class C
     a = 1
-    define_method "foo", Ractor.make_shareable(Proc.new{ a })
-    a = 2
-  end
-
-  Ractor.new{ C.new.foo }.take
-}
-
-# Ractor.make_shareable(a_proc) makes a proc shareable.
-assert_equal 'can not make a Proc shareable because it accesses outer variables (a).', %q{
-  a = b = nil
-  pr = Ractor.current.instance_eval do
-    Proc.new do
-      c = b # assign to a is okay because c is block local variable
-      # reading b is okay
-      a = b # assign to a is not allowed #=> Ractor::Error
-    end
+    define_method "foo", Ractor.shareable_proc{ a }
   end
 
-  begin
-    Ractor.make_shareable(pr)
-  rescue => e
-    e.message
-  end
+  Ractor.new{ C.new.foo }.value
 }
 
 # Ractor.make_shareable(obj, copy: true) makes copied shareable object.
@@ -1396,14 +1371,14 @@ assert_equal '[false, false, true, true]', %q{
 }
 
 # TracePoint with normal Proc should be Ractor local
-assert_equal '[4, 8]', %q{
+assert_equal '[6, 10]', %q{
   rs = []
   TracePoint.new(:line){|tp| rs << tp.lineno if tp.path == __FILE__}.enable do
-    Ractor.new{ # line 4
+    Ractor.new{ # line 5
       a = 1
       b = 2
-    }.take
-    c = 3       # line 8
+    }.value
+    c = 3       # line 9
   end
   rs
 }
@@ -1412,7 +1387,7 @@ assert_equal '[4, 8]', %q{
 assert_equal '[true, false]', %q{
   Ractor.new([[]].freeze) { |ary|
     [ary.frozen?, ary.first.frozen? ]
-  }.take
+  }.value
 }
 
 # Ractor deep copies frozen objects (str)
@@ -1420,7 +1395,7 @@ assert_equal '[true, false]', %q{
   s = String.new.instance_eval { @x = []; freeze}
   Ractor.new(s) { |s|
     [s.frozen?, s.instance_variable_get(:@x).frozen?]
-  }.take
+  }.value
 }
 
 # Can not trap with not isolated Proc on non-main ractor
@@ -1428,33 +1403,85 @@ assert_equal '[:ok, :ok]', %q{
   a = []
   Ractor.new{
     trap(:INT){p :ok}
-  }.take
+  }.join
   a << :ok
 
   begin
     Ractor.new{
       s = 'str'
       trap(:INT){p s}
-    }.take
-  rescue => Ractor::RemoteError
+    }.join
+  rescue Ractor::RemoteError
     a << :ok
   end
 }
 
+# Ractor.select is interruptible
+assert_normal_exit %q{
+  trap(:INT) do
+    exit
+  end
+
+  r = Ractor.new do
+    loop do
+      sleep 1
+    end
+  end
+
+  Thread.new do
+    sleep 0.5
+    Process.kill(:INT, Process.pid)
+  end
+  Ractor.select(r)
+}
+
 # Ractor-local storage
 assert_equal '[nil, "b", "a"]', %q{
   ans = []
   Ractor.current[:key] = 'a'
   r = Ractor.new{
-    Ractor.yield self[:key]
+    Ractor.main << self[:key]
     self[:key] = 'b'
     self[:key]
   }
-  ans << r.take
-  ans << r.take
+  ans << Ractor.receive
+  ans << r.value
   ans << Ractor.current[:key]
 }
 
+assert_equal '1', %q{
+  N = 1_000
+  Ractor.new{
+    a = []
+    1_000.times.map{|i|
+      Thread.new(i){|i|
+        Thread.pass if i < N
+        a << Ractor.store_if_absent(:i){ i }
+        a << Ractor.current[:i]
+      }
+    }.each(&:join)
+    a.uniq.size
+  }.value
+}
+
+# Ractor-local storage
+assert_equal '2', %q{
+  Ractor.new {
+    fails = 0
+    begin
+      Ractor.main[:key] # cannot get ractor local storage from non-main ractor
+    rescue => e
+      fails += 1 if e.message =~ /Cannot get ractor local/
+    end
+    begin
+      Ractor.main[:key] = 'val'
+    rescue => e
+      fails += 1 if e.message =~ /Cannot set ractor local/
+    end
+    fails
+  }.value
+}
+
 ###
 ### Synchronization tests
 ###
@@ -1468,51 +1495,54 @@ assert_equal "#{N}#{N}", %Q{
     Ractor.new{
       N.times{|i| -(i.to_s)}
     }
-  }.map{|r| r.take}.join
+  }.map{|r| r.value}.join
 }
 
-# enc_table
-assert_equal "#{N/10}", %Q{
-  Ractor.new do
-    loop do
-      Encoding.find("test-enc-#{rand(5_000)}").inspect
-    rescue ArgumentError => e
+assert_equal "ok", %Q{
+  N = #{N}
+  a, b = 2.times.map{
+    Ractor.new{
+      N.times.map{|i| -(i.to_s)}
+    }
+  }.map{|r| r.value}
+  N.times do |i|
+    unless a[i].equal?(b[i])
+      raise [a[i], b[i]].inspect
+    end
+    unless a[i] == i.to_s
+      raise [i, a[i], b[i]].inspect
     end
   end
-
-  src = Encoding.find("UTF-8")
-  #{N/10}.times{|i|
-    src.replicate("test-enc-\#{i}")
-  }
+  :ok
 }
 
-# Generic ivtbl
+# Generic fields_tbl
 n = N/2
 assert_equal "#{n}#{n}", %Q{
   2.times.map{
     Ractor.new do
       #{n}.times do
-        obj = ''
+        obj = +''
         obj.instance_variable_set("@a", 1)
         obj.instance_variable_set("@b", 1)
         obj.instance_variable_set("@c", 1)
         obj.instance_variable_defined?("@a")
       end
     end
-  }.map{|r| r.take}.join
+  }.map{|r| r.value}.join
 }
 
-# NameError
-assert_equal "ok", %q{
+# Now NoMethodError is copyable
+assert_equal "NoMethodError", %q{
+  obj = "".freeze # NameError refers the receiver indirectly
   begin
-    bar
+    obj.bar
   rescue => err
   end
-  begin
-    Ractor.new{} << err
-  rescue TypeError
-    'ok'
-  end
+
+  r = Ractor.new{ Ractor.receive }
+  r << err
+  r.value.class
 }
 
 assert_equal "ok", %q{
@@ -1530,53 +1560,997 @@ assert_equal "ok", %q{
 
 # Can yield back values while GC is sweeping [Bug #18117]
 assert_equal "ok", %q{
+  port = Ractor::Port.new
   workers = (0...8).map do
-    Ractor.new do
+    Ractor.new port do |port|
       loop do
         10_000.times.map { Object.new }
-        Ractor.yield Time.now
+        port << Time.now
+        Ractor.receive
       end
     end
   end
 
-  1_000.times { idle_worker, tmp_reporter = Ractor.select(*workers) }
+  100.times {
+    workers.each do
+      port.receive
+    end
+    workers.each do |w|
+      w.send(nil)
+    end
+  }
   "ok"
-}
+} if !yjit_enabled? && ENV['GITHUB_WORKFLOW'] != 'ModGC' # flaky
 
+# check method cache invalidation
 assert_equal "ok", %q{
-  def foo(*); ->{ super }; end
+  module M
+    def foo
+      @foo
+    end
+  end
+
+  class A
+    include M
+
+    def initialize
+      100.times { |i| instance_variable_set(:"@var_#{i}", "bad: #{i}") }
+      @foo = 2
+    end
+  end
+
+  class B
+    include M
+
+    def initialize
+      @foo = 1
+    end
+  end
+
+  Ractor.new do
+    b = B.new
+    100_000.times do
+      raise unless b.foo == 1
+    end
+  end
+
+  a = A.new
+  100_000.times do
+    raise unless a.foo == 2
+  end
+
+  "ok"
+}
+
+# check method cache invalidation
+assert_equal 'true', %q{
+  class C1; def self.foo = 1; end
+  class C2; def self.foo = 2; end
+  class C3; def self.foo = 3; end
+  class C4; def self.foo = 5; end
+  class C5; def self.foo = 7; end
+  class C6; def self.foo = 11; end
+  class C7; def self.foo = 13; end
+  class C8; def self.foo = 17; end
+
+  LN = 10_000
+  RN = 10
+  CS = [C1, C2, C3, C4, C5, C6, C7, C8]
+  rs = RN.times.map{|i|
+    Ractor.new(CS.shuffle){|cs|
+      LN.times.sum{
+        cs.inject(1){|r, c| r * c.foo} # c.foo invalidates method cache entry
+      }
+    }
+  }
+
+  n = CS.inject(1){|r, c| r * c.foo} * LN
+  rs.map{|r| r.value} == Array.new(RN){n}
+}
+
+# check method cache invalidation
+assert_equal 'true', %q{
+  class Foo
+    def hello = nil
+  end
+
+  r1 = Ractor.new do
+    1000.times do
+      class Foo
+        def hello = nil
+      end
+    end
+  end
+
+  r2 = Ractor.new do
+    1000.times do
+      o = Foo.new
+      o.hello
+    end
+  end
+
+  r1.value
+  r2.value
+
+  true
+}
+
+# check experimental warning
+assert_match /\Atest_ractor\.rb:1:\s+warning:\s+Ractor API is experimental/, %q{
+  Warning[:experimental] = $VERBOSE = true
+  STDERR.reopen(STDOUT)
+  eval("Ractor.new{}.value", nil, "test_ractor.rb", 1)
+}, frozen_string_literal: false
+
+# check moved object
+assert_equal 'ok', %q{
+  r = Ractor.new do
+    Ractor.receive
+    GC.start
+    :ok
+  end
+
+  obj = begin
+  raise
+  rescue => e
+    e = Marshal.load(Marshal.dump(e))
+  end
+
+  r.send obj, move: true
+  r.value
+}
+
+## Ractor::Selector
+
+# Selector#empty? returns true
+assert_equal 'true', %q{
+  skip true unless defined? Ractor::Selector
+
+  s = Ractor::Selector.new
+  s.empty?
+}
+
+# Selector#empty? returns false if there is target ractors
+assert_equal 'false', %q{
+  skip false unless defined? Ractor::Selector
+
+  s = Ractor::Selector.new
+  s.add Ractor.new{}
+  s.empty?
+}
+
+# Selector#clear removes all ractors from the waiting list
+assert_equal 'true', %q{
+  skip true unless defined? Ractor::Selector
+
+  s = Ractor::Selector.new
+  s.add Ractor.new{10}
+  s.add Ractor.new{20}
+  s.clear
+  s.empty?
+}
+
+# Selector#wait can wait multiple ractors
+assert_equal '[10, 20, true]', %q{
+  skip [10, 20, true] unless defined? Ractor::Selector
+
+  s = Ractor::Selector.new
+  s.add Ractor.new{10}
+  s.add Ractor.new{20}
+  r, v = s.wait
+  vs = []
+  vs << v
+  r, v = s.wait
+  vs << v
+  [*vs.sort, s.empty?]
+} if defined? Ractor::Selector
+
+# Selector#wait can wait multiple ractors with receiving.
+assert_equal '30', %q{
+  skip 30 unless defined? Ractor::Selector
+
+  RN = 30
+  rs = RN.times.map{
+    Ractor.new{ :v }
+  }
+  s = Ractor::Selector.new(*rs)
+
+  results = []
+  until s.empty?
+    results << s.wait
+
+    # Note that s.wait can raise an exception because other Ractors/Threads
+    # can take from the same ractors in the waiting set.
+    # In this case there is no other takers so `s.wait` doesn't raise an error.
+  end
+
+  results.size
+} if defined? Ractor::Selector
+
+# Selector#wait can support dynamic addition
+assert_equal '600', %q{
+  skip 600 unless defined? Ractor::Selector
+
+  RN = 100
+  s = Ractor::Selector.new
+  port = Ractor::Port.new
+  rs = RN.times.map{
+    Ractor.new{
+      Ractor.main << Ractor.new(port){|port| port << :v3; :v4 }
+      Ractor.main << Ractor.new(port){|port| port << :v5; :v6 }
+      Ractor.yield :v1
+      :v2
+    }
+  }
+
+  rs.each{|r| s.add(r)}
+  h = {v1: 0, v2: 0, v3: 0, v4: 0, v5: 0, v6: 0}
+
+  loop do
+    case s.wait receive: true
+    in :receive, r
+      s.add r
+    in r, v
+      h[v] += 1
+      break if h.all?{|k, v| v == RN}
+    end
+  end
+
+  h.sum{|k, v| v}
+} unless yjit_enabled? # http://ci.rvm.jp/results/trunk-yjit@ruby-sp2-docker/4466770
+
+# Selector should be GCed (free'ed) without trouble
+assert_equal 'ok', %q{
+  skip :ok unless defined? Ractor::Selector
+
+  RN = 30
+  rs = RN.times.map{
+    Ractor.new{ :v }
+  }
+  s = Ractor::Selector.new(*rs)
+  :ok
+}
+
+end # if !ENV['GITHUB_WORKFLOW']
+
+# Chilled strings are not shareable
+assert_equal 'false', %q{
+  Ractor.shareable?("chilled")
+}
+
+# Chilled strings can be made shareable
+assert_equal 'true', %q{
+  shareable = Ractor.make_shareable("chilled")
+  shareable == "chilled" && Ractor.shareable?(shareable)
+}
+
+# require in Ractor
+assert_equal 'true', %q{
+  Module.new do
+    def require feature
+      return Ractor._require(feature) unless Ractor.main?
+      super
+    end
+    Object.prepend self
+    set_temporary_name 'Ractor#require'
+  end
+
+  Ractor.new{
+    begin
+      require 'tempfile'
+      Tempfile.new
+    rescue SystemStackError
+      # prism parser with -O0 build consumes a lot of machine stack
+      Data.define(:fileno).new(1)
+    end
+  }.value.fileno > 0
+}
+
+# require_relative in Ractor
+assert_equal 'true', %q{
+  dummyfile = File.join(__dir__, "dummy#{rand}.rb")
+  return true if File.exist?(dummyfile)
+
   begin
-    Ractor.make_shareable(foo)
-  rescue Ractor::IsolationError
-    "ok"
+    File.write dummyfile, ''
+  rescue Exception
+    # skip on any errors
+    return true
+  end
+
+  begin
+    Ractor.new dummyfile do |f|
+      require_relative File.basename(f)
+    end.value
+  ensure
+    File.unlink dummyfile
   end
 }
 
-assert_equal "ok", %q{
-  def foo(**); ->{ super }; end
+# require_relative in Ractor
+assert_equal 'LoadError', %q{
+  dummyfile = File.join(__dir__, "not_existed_dummy#{rand}.rb")
+  return true if File.exist?(dummyfile)
+
+  Ractor.new dummyfile do |f|
+    begin
+      require_relative File.basename(f)
+    rescue LoadError => e
+      e.class
+    end
+  end.value
+}
+
+# autolaod in Ractor
+assert_equal 'true', %q{
+  autoload :Tempfile, 'tempfile'
+
+  r = Ractor.new do
+    begin
+      Tempfile.new
+    rescue SystemStackError
+      # prism parser with -O0 build consumes a lot of machine stack
+      Data.define(:fileno).new(1)
+    end
+  end
+  r.value.fileno > 0
+}
+
+# failed in autolaod in Ractor
+assert_equal 'LoadError', %q{
+  dummyfile = File.join(__dir__, "not_existed_dummy#{rand}.rb")
+  autoload :Tempfile, dummyfile
+
+  r = Ractor.new do
+    begin
+      Tempfile.new
+    rescue LoadError => e
+      e.class
+    end
+  end
+  r.value
+}
+
+# bind_call in Ractor [Bug #20934]
+assert_equal 'ok', %q{
+  2.times.map do
+    Ractor.new do
+      1000.times do
+        Object.instance_method(:itself).bind_call(self)
+      end
+    end
+  end.each(&:join)
+  GC.start
+  :ok.itself
+}
+
+# moved objects being corrupted if embeded (String)
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = "foobarbazfoobarbazfoobarbazfoobarbaz"
+  ractor.send(obj.dup, move: true)
+  roundtripped_obj = ractor.value
+  roundtripped_obj == obj ? :ok : roundtripped_obj
+}
+
+# moved objects being corrupted if embeded (Array)
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = Array.new(10, 42)
+  ractor.send(obj.dup, move: true)
+  roundtripped_obj = ractor.value
+  roundtripped_obj == obj ? :ok : roundtripped_obj
+}
+
+# moved objects being corrupted if embeded (Hash)
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = { foo: 1, bar: 2 }
+  ractor.send(obj.dup, move: true)
+  roundtripped_obj = ractor.value
+  roundtripped_obj == obj ? :ok : roundtripped_obj
+}
+
+# moved objects being corrupted if embeded (MatchData)
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = "foo".match(/o/)
+  ractor.send(obj.dup, move: true)
+  roundtripped_obj = ractor.value
+  roundtripped_obj == obj ? :ok : roundtripped_obj
+}
+
+# moved objects being corrupted if embeded (Struct)
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = Struct.new(:a, :b, :c, :d, :e, :f).new(1, 2, 3, 4, 5, 6)
+  ractor.send(obj.dup, move: true)
+  roundtripped_obj = ractor.value
+  roundtripped_obj == obj ? :ok : roundtripped_obj
+}
+
+# moved objects being corrupted if embeded (Object)
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  class SomeObject
+    attr_reader :a, :b, :c, :d, :e, :f
+    def initialize
+      @a = @b = @c = @d = @e = @f = 1
+    end
+
+    def ==(o)
+      @a == o.a &&
+      @b == o.b &&
+      @c == o.c &&
+      @d == o.d &&
+      @e == o.e &&
+      @f == o.f
+    end
+  end
+
+  SomeObject.new # initial non-embeded
+
+  obj = SomeObject.new
+  ractor.send(obj.dup, move: true)
+  roundtripped_obj = ractor.value
+  roundtripped_obj == obj ? :ok : roundtripped_obj
+}
+
+# moved arrays can't be used
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = [1]
+  ractor.send(obj, move: true)
   begin
-    Ractor.make_shareable(foo)
-  rescue Ractor::IsolationError
-    "ok"
+    [].concat(obj)
+  rescue TypeError
+    :ok
+  else
+    :fail
   end
 }
 
-assert_equal "ok", %q{
-  def foo(...); ->{ super }; end
+# moved strings can't be used
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = "hello"
+  ractor.send(obj, move: true)
   begin
-    Ractor.make_shareable(foo)
-  rescue Ractor::IsolationError
-    "ok"
+    "".replace(obj)
+  rescue TypeError
+    :ok
+  else
+    :fail
   end
 }
 
-assert_equal "ok", %q{
-  def foo((x), (y)); ->{ super }; end
+# moved hashes can't be used
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = { a: 1 }
+  ractor.send(obj, move: true)
   begin
-    Ractor.make_shareable(foo([], []))
-  rescue Ractor::IsolationError
-    "ok"
+    {}.merge(obj)
+  rescue TypeError
+    :ok
+  else
+    :fail
   end
 }
 
-end # if !ENV['GITHUB_WORKFLOW']
+# move objects inside frozen containers
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = Array.new(10, 42)
+  original = obj.dup
+  ractor.send([obj].freeze, move: true)
+  roundtripped_obj = ractor.value[0]
+  roundtripped_obj == original ? :ok : roundtripped_obj
+}
+
+# move object with generic ivar
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = Array.new(10, 42)
+  obj.instance_variable_set(:@array, [1])
+
+  ractor.send(obj, move: true)
+  roundtripped_obj = ractor.value
+  roundtripped_obj.instance_variable_get(:@array) == [1] ? :ok : roundtripped_obj
+}
+
+# move object with many generic ivars
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = Array.new(10, 42)
+  0.upto(300) do |i|
+    obj.instance_variable_set(:"@array#{i}", [i])
+  end
+
+  ractor.send(obj, move: true)
+  roundtripped_obj = ractor.value
+  roundtripped_obj.instance_variable_get(:@array1) == [1] ? :ok : roundtripped_obj
+}
+
+# move object with complex generic ivars
+assert_equal 'ok', %q{
+  # Make Array too_complex
+  30.times { |i| [].instance_variable_set(:"@complex#{i}", 1) }
+
+  ractor = Ractor.new { Ractor.receive }
+  obj = Array.new(10, 42)
+  obj.instance_variable_set(:@array1, [1])
+
+  ractor.send(obj, move: true)
+  roundtripped_obj = ractor.value
+  roundtripped_obj.instance_variable_get(:@array1) == [1] ? :ok : roundtripped_obj
+}
+
+# move object with generic ivars and existing id2ref table
+# [Bug #21664]
+assert_equal 'ok', %q{
+  obj = [1]
+  obj.instance_variable_set("@field", :ok)
+  ObjectSpace._id2ref(obj.object_id) # build id2ref table
+
+  ractor = Ractor.new { Ractor.receive }
+  ractor.send(obj, move: true)
+  obj = ractor.value
+  obj.instance_variable_get("@field")
+}
+
+# copy object with complex generic ivars
+assert_equal 'ok', %q{
+  # Make Array too_complex
+  30.times { |i| [].instance_variable_set(:"@complex#{i}", 1) }
+
+  ractor = Ractor.new { Ractor.receive }
+  obj = Array.new(10, 42)
+  obj.instance_variable_set(:@array1, [1])
+
+  ractor.send(obj)
+  roundtripped_obj = ractor.value
+  roundtripped_obj.instance_variable_get(:@array1) == [1] ? :ok : roundtripped_obj
+}
+
+# copy object with many generic ivars
+assert_equal 'ok', %q{
+  ractor = Ractor.new { Ractor.receive }
+  obj = Array.new(10, 42)
+  0.upto(300) do |i|
+    obj.instance_variable_set(:"@array#{i}", [i])
+  end
+
+  ractor.send(obj)
+  roundtripped_obj = ractor.value
+  roundtripped_obj.instance_variable_get(:@array1) == [1] ? :ok : roundtripped_obj
+}
+
+# moved composite types move their non-shareable parts properly
+assert_equal 'ok', %q{
+  k, v = String.new("key"), String.new("value")
+  h = { k => v }
+  h.instance_variable_set("@b", String.new("b"))
+  a = [k,v]
+  o_singleton = Object.new
+  def o_singleton.a
+    @a
+  end
+  o_singleton.instance_variable_set("@a", String.new("a"))
+  class MyObject
+    attr_reader :a
+    def initialize(a)
+      @a = a
+    end
+  end
+  struct_class = Struct.new(:a)
+  struct = struct_class.new(String.new('a'))
+  o = MyObject.new(String.new('a'))
+  port = Ractor::Port.new
+
+  r = Ractor.new port do |port|
+    loop do
+      obj = Ractor.receive
+      val = case obj
+      when Hash
+        obj['key'] == 'value' && obj.instance_variable_get("@b") == 'b'
+      when Array
+        obj[0] == 'key'
+      when Struct
+        obj.a == 'a'
+      when Object
+        obj.a == 'a'
+      end
+      port << val
+    end
+  end
+
+  objs = [h, a, o_singleton, o, struct]
+  objs.each_with_index do |obj, i|
+    klass = obj.class
+    parts_moved = {}
+    case obj
+    when Hash
+      parts_moved[klass] = [obj['key'], obj.instance_variable_get("@b")]
+    when Array
+      parts_moved[klass] = obj.dup # the contents
+    when Struct, Object
+      parts_moved[klass] = [obj.a]
+    end
+    r.send(obj, move: true)
+    val = port.receive
+    if val != true
+      raise "bad val in ractor for obj at i:#{i}"
+    end
+    begin
+      p obj
+    rescue
+    else
+      raise "should be moved"
+    end
+    parts_moved.each do |klass, parts|
+      parts.each_with_index do |part, j|
+        case part
+        when Ractor::MovedObject
+        else
+          raise "part for class #{klass} at i:#{j} should be moved"
+        end
+      end
+    end
+  end
+  'ok'
+}
+
+# fork after creating Ractor
+assert_equal 'ok', %q{
+begin
+  Ractor.new { Ractor.receive }
+  _, status = Process.waitpid2 fork { }
+  status.success? ? "ok" : status
+rescue NotImplementedError
+  :ok
+end
+}
+
+# Ractors should be terminated after fork
+assert_equal 'ok', %q{
+begin
+  r = Ractor.new { Ractor.receive }
+  _, status = Process.waitpid2 fork {
+    begin
+      raise if r.value != nil
+    end
+  }
+  r.send(123)
+  raise unless r.value == 123
+  status.success? ? "ok" : status
+rescue NotImplementedError
+  :ok
+end
+}
+
+# Ractors should be terminated after fork
+assert_equal 'ok', %q{
+begin
+  r = Ractor.new { Ractor.receive }
+  _, status = Process.waitpid2 fork {
+    begin
+      r.send(123)
+    rescue Ractor::ClosedError
+    end
+  }
+  r.send(123)
+  raise unless r.value == 123
+  status.success? ? "ok" : status
+rescue NotImplementedError
+  :ok
+end
+}
+
+# Creating classes inside of Ractors
+# [Bug #18119]
+assert_equal 'ok', %q{
+  port = Ractor::Port.new
+  workers = (0...8).map do
+    Ractor.new port do |port|
+      loop do
+        100.times.map { Class.new }
+        port << nil
+      end
+    end
+  end
+
+  100.times { port.receive }
+
+  'ok'
+}
+
+# Using Symbol#to_proc inside ractors
+# [Bug #21354]
+assert_equal 'ok', %q{
+  :inspect.to_proc
+  Ractor.new do
+    # It should not use this cached proc, it should create a new one. If it used
+    # the cached proc, we would get a ractor_confirm_belonging error here.
+    :inspect.to_proc
+  end.join
+  'ok'
+}
+
+# take vm lock when deleting generic ivars from the global table
+assert_equal 'ok', %q{
+  Ractor.new do
+    a = [1, 2, 3]
+    a.object_id
+    a.dup # this deletes generic ivar on dupped object
+    'ok'
+  end.value
+}
+
+## Ractor#monitor
+
+# monitor port returns `:exited` when the monitering Ractor terminated.
+assert_equal 'true', %q{
+  r = Ractor.new do
+    Ractor.main << :ok1
+    :ok2
+  end
+
+  r.monitor port = Ractor::Port.new
+  Ractor.receive # :ok1
+  port.receive == :exited
+}
+
+# monitor port returns `:exited` even if the monitoring Ractor was terminated.
+assert_equal 'true', %q{
+  r = Ractor.new do
+    :ok
+  end
+
+  r.join # wait for r's terminateion
+
+  r.monitor port = Ractor::Port.new
+  port.receive == :exited
+}
+
+# monitor returns false if the monitoring Ractor was terminated.
+assert_equal 'false', %q{
+  r = Ractor.new do
+    :ok
+  end
+
+  r.join # wait for r's terminateion
+
+  r.monitor Ractor::Port.new
+}
+
+# monitor port returns `:aborted` when the monitering Ractor is aborted.
+assert_equal 'true', %q{
+  r = Ractor.new do
+    Ractor.main << :ok1
+    raise 'ok'
+  end
+
+  r.monitor port = Ractor::Port.new
+  Ractor.receive # :ok1
+  port.receive == :aborted
+}
+
+# monitor port returns `:aborted` even if the monitoring Ractor was aborted.
+assert_equal 'true', %q{
+  r = Ractor.new do
+    raise 'ok'
+  end
+
+  begin
+    r.join # wait for r's terminateion
+  rescue Ractor::RemoteError
+    # ignore
+  end
+
+  r.monitor port = Ractor::Port.new
+  port.receive == :aborted
+}
+
+## Ractor#join
+
+# Ractor#join returns self when the Ractor is terminated.
+assert_equal 'true', %q{
+  r = Ractor.new do
+    Ractor.receive
+  end
+
+  r << :ok
+  r.join
+  r.inspect in /terminated/
+} if false # TODO
+
+# Ractor#join raises RemoteError when the remote Ractor aborted with an exception
+assert_equal 'err', %q{
+  r = Ractor.new do
+    raise 'err'
+  end
+
+  begin
+    r.join
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
+## Ractor#value
+
+# Ractor#value returns the last expression even if it is unshareable
+assert_equal 'true', %q{
+  r = Ractor.new do
+    obj = [1, 2]
+    obj << obj.object_id
+  end
+
+  ret = r.value
+  ret == [1, 2, ret.object_id]
+}
+
+# Only one Ractor can call Ractor#value
+assert_equal '[["Only the successor ractor can take a value", 9], ["ok", 2]]', %q{
+  r = Ractor.new do
+    'ok'
+  end
+
+  RN = 10
+
+  rs = RN.times.map do
+    Ractor.new r do |r|
+      begin
+        Ractor.main << r.value
+        Ractor.main << r.value # this ractor can get same result
+      rescue Ractor::Error => e
+        Ractor.main << e.message
+      end
+    end
+  end
+
+  (RN+1).times.map{
+    Ractor.receive
+  }.tally.sort
+}
+
+# Cause lots of inline CC misses.
+assert_equal 'ok', <<~'RUBY'
+  class A; def test; 1 + 1; end; end
+  class B; def test; 1 + 1; end; end
+  class C; def test; 1 + 1; end; end
+  class D; def test; 1 + 1; end; end
+  class E; def test; 1 + 1; end; end
+  class F; def test; 1 + 1; end; end
+  class G; def test; 1 + 1; end; end
+
+  objs = [A.new, B.new, C.new, D.new, E.new, F.new, G.new].freeze
+
+  def call_test(obj)
+    obj.test
+  end
+
+  ractors = 7.times.map do
+    Ractor.new(objs) do |objs|
+      objs = objs.shuffle
+      100_000.times do
+        objs.each do |o|
+          call_test(o)
+        end
+      end
+    end
+  end
+  ractors.each(&:join)
+  :ok
+RUBY
+
+# This test checks that we do not trigger a GC when we have malloc with Ractor
+# locks. We cannot trigger a GC with Ractor locks because GC requires VM lock
+# and Ractor barrier. If another Ractor is waiting on this Ractor lock, then it
+# will deadlock because the other Ractor will never join the barrier.
+#
+# Creating Ractor::Port requires locking the Ractor and inserting into an
+# st_table, which can call malloc.
+assert_equal 'ok', <<~'RUBY'
+  r = Ractor.new do
+    loop do
+      Ractor::Port.new
+    end
+  end
+
+  10.times do
+    10_000.times do
+      r.send(nil)
+    end
+    sleep(0.01)
+  end
+  :ok
+RUBY
+
+assert_equal 'ok', <<~'RUBY'
+  begin
+    100.times do |i|
+      Ractor.new(i) do |j|
+        1000.times do |i|
+          "#{j}-#{i}"
+        end
+        Ractor.receive
+      end
+      pid = fork { }
+      _, status = Process.waitpid2 pid
+      raise unless status.success?
+    end
+
+    :ok
+  rescue NotImplementedError
+    :ok
+  end
+RUBY
+
+assert_equal 'ok', <<~'RUBY'
+  begin
+    100.times do |i|
+      Ractor.new(i) do |j|
+        1000.times do |i|
+          "#{j}-#{i}"
+        end
+      end
+      pid = fork do
+        GC.verify_internal_consistency
+      end
+      _, status = Process.waitpid2 pid
+      raise unless status.success?
+    end
+
+    :ok
+  rescue NotImplementedError
+    :ok
+  end
+RUBY
+
+# When creating bmethods in Ractors, they should only be usable from their
+# defining ractor, even if it is GC'd
+assert_equal 'ok', <<~'RUBY'
+
+begin
+  CLASSES = 1000.times.map { Class.new }.freeze
+
+  # This would be better to run in parallel, but there's a bug with lambda
+  # creation and YJIT causing crashes in dev mode
+  ractors = CLASSES.map do |klass|
+    Ractor.new(klass) do |klass|
+      Ractor.receive
+      klass.define_method(:foo) {}
+    end
+  end
+
+  ractors.each do |ractor|
+    ractor << nil
+    ractor.join
+  end
+
+  ractors.clear
+  GC.start
+
+  any = 1000.times.map do
+    Ractor.new do
+      CLASSES.any? do |klass|
+        begin
+          klass.new.foo
+          true
+        rescue RuntimeError
+          false
+        end
+      end
+    end
+  end.map(&:value).none? && :ok
+rescue ThreadError => e
+  # ignore limited memory machine
+  if /can\'t create Thread/ =~ e.message
+    :ok
+  else
+    raise
+  end
+end
+RUBY
diff --git a/bootstraptest/test_syntax.rb b/bootstraptest/test_syntax.rb
index 948e2d7809..fbc9c6f62e 100644
--- a/bootstraptest/test_syntax.rb
+++ b/bootstraptest/test_syntax.rb
@@ -528,24 +528,24 @@ assert_equal %q{1}, %q{
   i
 }
 def assert_syntax_error expected, code, message = ''
-  assert_equal "#{expected}",
-    "begin eval(%q{#{code}}, nil, '', 0)"'; rescue SyntaxError => e; e.message[/\A:(?:\d+:)? (.*)/, 1] end', message
+  assert_match /^#{Regexp.escape(expected)}/,
+    "begin eval(%q{#{code}}, nil, '', 0)"'; rescue SyntaxError => e; e.message[/(?:\^~*|\A:(?:\d+:)?(?! syntax errors? found)(?: syntax error,)?) (.*)/, 1] end', message
 end
 assert_syntax_error "unterminated string meets end of file", '().."', '[ruby-dev:29732]'
 assert_equal %q{[]}, %q{$&;[]}, '[ruby-dev:31068]'
-assert_syntax_error "syntax error, unexpected *, expecting '}'", %q{{*0}}, '[ruby-dev:31072]'
-assert_syntax_error "`@0' is not allowed as an instance variable name", %q{@0..0}, '[ruby-dev:31095]'
-assert_syntax_error "identifier $00 is not valid to get", %q{$00..0}, '[ruby-dev:31100]'
-assert_syntax_error "identifier $00 is not valid to set", %q{0..$00=1}
+assert_syntax_error "unexpected *, expecting '}'", %q{{*0}}, '[ruby-dev:31072]'
+assert_syntax_error "'@0' is not allowed as an instance variable name", %q{@0..0}, '[ruby-dev:31095]'
+assert_syntax_error "'$00' is not allowed as a global variable name", %q{$00..0}, '[ruby-dev:31100]'
+assert_syntax_error "'$00' is not allowed as a global variable name", %q{0..$00=1}
 assert_equal %q{0}, %q{[*0];0}, '[ruby-dev:31102]'
-assert_syntax_error "syntax error, unexpected ')'", %q{v0,(*,v1,) = 0}, '[ruby-dev:31104]'
+assert_syntax_error "unexpected ')'", %q{v0,(*,v1,) = 0}, '[ruby-dev:31104]'
 assert_equal %q{1}, %q{
   class << (ary=[]); def []; 0; end; def []=(x); super(0,x);end;end; ary[]+=1
 }, '[ruby-dev:31110]'
 assert_syntax_error "Can't set variable $1", %q{0..$1=1}, '[ruby-dev:31118]'
 assert_valid_syntax %q{1.times{1+(1&&next)}}, '[ruby-dev:31119]'
 assert_valid_syntax %q{x=-1;loop{x+=1&&redo if (x+=1).zero?}}, '[ruby-dev:31119]'
-assert_syntax_error %q{syntax error, unexpected end-of-input}, %q{!}, '[ruby-dev:31243]'
+assert_syntax_error %q{unexpected end-of-input}, %q{!}, '[ruby-dev:31243]'
 assert_equal %q{[nil]}, %q{[()]}, '[ruby-dev:31252]'
 assert_equal %q{true}, %q{!_=()}, '[ruby-dev:31263]'
 assert_equal 'ok', %q{while true; redo; end if 1 == 2; :ok}, '[ruby-dev:31360]'
@@ -629,7 +629,7 @@ assert_equal '2', %q{
 
 assert_match /invalid multibyte char/, %q{
   $stderr = STDOUT
-  eval("\"\xf0".force_encoding("utf-8"))
+  eval("\"\xf0".dup.force_encoding("utf-8"))
 }, '[ruby-dev:32429]'
 
 # method ! and !=
@@ -904,3 +904,35 @@ assert_normal_exit %q{
     Class
   end
 }, '[ruby-core:30293]'
+
+assert_equal "false", <<~RUBY, "literal strings are mutable", "--disable-frozen-string-literal"
+  'test'.frozen?
+RUBY
+
+assert_equal "true", <<~RUBY, "literal strings are frozen", "--disable-frozen-string-literal", frozen_string_literal: true
+  'test'.frozen?
+RUBY
+
+assert_equal "true", <<~RUBY, "literal strings are frozen", "--enable-frozen-string-literal"
+  'test'.frozen?
+RUBY
+
+assert_equal "false", <<~RUBY, "literal strings are mutable", "--enable-frozen-string-literal", frozen_string_literal: false
+  'test'.frozen?
+RUBY
+
+assert_equal "false", <<~RUBY, "__FILE__ is mutable", "--disable-frozen-string-literal"
+  __FILE__.frozen?
+RUBY
+
+assert_equal "true", <<~RUBY, "__FILE__ is frozen", "--disable-frozen-string-literal", frozen_string_literal: true
+  __FILE__.frozen?
+RUBY
+
+assert_equal "true", <<~RUBY, "__FILE__ is frozen", "--enable-frozen-string-literal"
+  __FILE__.frozen?
+RUBY
+
+assert_equal "false", <<~RUBY, "__FILE__ is mutable", "--enable-frozen-string-literal", frozen_string_literal: false
+  __FILE__.frozen?
+RUBY
diff --git a/bootstraptest/test_thread.rb b/bootstraptest/test_thread.rb
index 5361828403..7ff5bb4a38 100644
--- a/bootstraptest/test_thread.rb
+++ b/bootstraptest/test_thread.rb
@@ -242,9 +242,22 @@ assert_equal 'true', %{
   end
 }
 
+assert_equal 'true', %{
+  Thread.new{}.join
+  begin
+    Process.waitpid2 fork{
+      Thread.new{
+        sleep 0.1
+      }.join
+    }
+    true
+  rescue NotImplementedError
+    true
+  end
+}
+
 assert_equal 'ok', %{
-  open("zzz_t1.rb", "w") do |f|
-    f.puts <<-END
+  File.write("zzz_t1.rb", <<-END)
       begin
         Thread.new { fork { GC.start } }.join
         pid, status = Process.wait2
@@ -253,7 +266,6 @@ assert_equal 'ok', %{
         $result = :ok
       end
     END
-  end
   require "./zzz_t1.rb"
   $result
 }
@@ -408,8 +420,7 @@ assert_equal 'ok', %q{
 }
 
 assert_equal 'ok', %{
-  open("zzz_t2.rb", "w") do |f|
-    f.puts <<-'end;' # do
+  File.write("zzz_t2.rb", <<-'end;') # do
       begin
         m = Thread::Mutex.new
         parent = Thread.current
@@ -431,7 +442,6 @@ assert_equal 'ok', %{
         $result = :ok
       end
     end;
-  end
   require "./zzz_t2.rb"
   $result
 }
@@ -484,6 +494,7 @@ assert_equal 'foo', %q{
   GC.start
   f.call.source
 }
+
 assert_normal_exit %q{
   class C
     def inspect
diff --git a/bootstraptest/test_yjit.rb b/bootstraptest/test_yjit.rb
index 2dff7d591a..be66395190 100644
--- a/bootstraptest/test_yjit.rb
+++ b/bootstraptest/test_yjit.rb
@@ -1,3 +1,318 @@
+# To run the tests in this file only, with YJIT enabled:
+# make btest BTESTS=bootstraptest/test_yjit.rb RUN_OPTS="--yjit-call-threshold=1"
+
+# regression test for popping before side exit
+assert_equal "ok", %q{
+  def foo(a, *) = a
+
+  def call(args, &)
+    foo(1) # spill at where the block arg will be
+    foo(*args, &)
+  end
+
+  call([1, 2])
+
+  begin
+    call([])
+  rescue ArgumentError
+    :ok
+  end
+}
+
+# regression test for send processing before side exit
+assert_equal "ok", %q{
+  def foo(a, *) = :foo
+
+  def call(args)
+    send(:foo, *args)
+  end
+
+  call([1, 2])
+
+  begin
+    call([])
+  rescue ArgumentError
+    :ok
+  end
+}
+
+# test discarding extra yield arguments
+assert_equal "22131300500015901015", %q{
+  def splat_kw(ary) = yield *ary, a: 1
+
+  def splat(ary) = yield *ary
+
+  def kw = yield 1, 2, a: 3
+
+  def kw_only = yield a: 0
+
+  def simple = yield 0, 1
+
+  def none = yield
+
+  def calls
+    [
+      splat([1, 1, 2]) { |x, y| x + y },
+      splat([1, 1, 2]) { |y, opt = raise| opt + y},
+      splat_kw([0, 1]) { |a:| a },
+      kw { |a:| a },
+      kw { |one| one },
+      kw { |one, a:| a },
+      kw_only { |a:| a },
+      kw_only { |a: 1| a },
+      simple { 5.itself },
+      simple { |a| a },
+      simple { |opt = raise| opt },
+      simple { |*rest| rest },
+      simple { |opt_kw: 5| opt_kw },
+      none { |a: 9| a },
+      # autosplat ineractions
+      [0, 1, 2].yield_self { |a, b| [a, b] },
+      [0, 1, 2].yield_self { |a, opt = raise| [a, opt] },
+      [1].yield_self { |a, opt = 4| a + opt },
+    ]
+  end
+
+  calls.join
+}
+
+# test autosplat with empty splat
+assert_equal "ok", %q{
+  def m(pos, splat) = yield pos, *splat
+
+  m([:ok], []) {|v0,| v0 }
+}
+
+# regression test for send stack shifting
+assert_normal_exit %q{
+  def foo(a, b)
+    a.singleton_methods(b)
+  end
+
+  def call_foo
+    [1, 1, 1, 1, 1, 1, send(:foo, 1, 1)]
+  end
+
+  call_foo
+}
+
+# regression test for keyword splat with yield
+assert_equal 'nil', %q{
+  def splat_kw(kwargs) = yield(**kwargs)
+
+  splat_kw({}) { _1 }.inspect
+}
+
+# regression test for arity check with splat
+assert_equal '[:ae, :ae]', %q{
+  def req_one(a_, b_ = 1) = raise
+
+  def test(args)
+    req_one *args
+  rescue ArgumentError
+    :ae
+  end
+
+  [test(Array.new 5), test([])]
+}
+
+# regression test for arity check with splat and send
+assert_equal '[:ae, :ae]', %q{
+  def two_reqs(a, b_, _ = 1) = a.gsub(a, a)
+
+  def test(name, args)
+    send(name, *args)
+  rescue ArgumentError
+    :ae
+  end
+
+  [test(:two_reqs, ["g", nil, nil, nil]), test(:two_reqs, ["g"])]
+}
+
+# regression test for GC marking stubs in invalidated code
+assert_normal_exit %q{
+  skip true unless GC.respond_to?(:compact)
+  garbage = Array.new(10_000) { [] } # create garbage to cause iseq movement
+  eval(<<~RUBY)
+  def foo(n, garbage)
+    if n == 2
+      # 1.times.each to create a cfunc frame to preserve the JIT frame
+      # which will return to a stub housed in an invalidated block
+      return 1.times.each do
+        Object.define_method(:foo) {}
+        garbage.clear
+        GC.verify_compaction_references(toward: :empty, expand_heap: true)
+      end
+    end
+
+    foo(n + 1, garbage)
+  end
+  RUBY
+
+  foo(1, garbage)
+}
+
+# regression test for callee block handler overlapping with arguments
+assert_equal '3', %q{
+  def foo(_req, *args) = args.last
+
+  def call_foo = foo(0, 1, 2, 3, &->{})
+
+  call_foo
+}
+
+# call leaf builtin with a block argument
+assert_equal '0', "0.abs(&nil)"
+
+# regression test for invokeblock iseq guard
+assert_equal 'ok', %q{
+  skip :ok unless GC.respond_to?(:compact)
+  def foo = yield
+  10.times do |i|
+    ret = eval("foo { #{i} }")
+    raise "failed at #{i}" unless ret == i
+    GC.compact
+  end
+  :ok
+}
+
+# regression test for overly generous guard elision
+assert_equal '[0, :sum, 0, :sum]', %q{
+  # In faulty versions, the following happens:
+  #  1. YJIT puts object on the temp stack with type knowledge
+  #     (CArray or CString) about RBASIC_CLASS(object).
+  #  2. In iter=0, due to the type knowledge, YJIT generates
+  #     a call to sum() without any guard on RBASIC_CLASS(object).
+  #  3. In iter=1, a singleton class is added to the object,
+  #     changing RBASIC_CLASS(object), falsifying the type knowledge.
+  #  4. Because the code from (1) has no class guard, it is incorrectly
+  #     reused and the wrong method is invoked.
+  # Putting a literal is important for gaining type knowledge.
+  def carray(iter)
+    array = []
+    array.sum(iter.times { def array.sum(_) = :sum })
+  end
+
+  def cstring(iter)
+    string = "".dup
+    string.sum(iter.times { def string.sum(_) = :sum })
+  end
+
+  [carray(0), carray(1), cstring(0), cstring(1)]
+}
+
+# regression test for return type of Integer#/
+# It can return a T_BIGNUM when inputs are T_FIXNUM.
+assert_equal 0x3fffffffffffffff.to_s, %q{
+  def call(fixnum_min)
+    (fixnum_min / -1) - 1
+  end
+
+  call(-(2**62))
+}
+
+# regression test for return type of String#<<
+assert_equal 'Sub', %q{
+  def call(sub) = (sub << sub).itself
+
+  class Sub < String; end
+
+  call(Sub.new('o')).class
+}
+
+# String#dup with generic ivars
+assert_equal '["str", "ivar"]', %q{
+  def str_dup(str) = str.dup
+  str = "str"
+  str.instance_variable_set(:@ivar, "ivar")
+  str = str_dup(str)
+  [str, str.instance_variable_get(:@ivar)]
+}
+
+# test splat filling required and feeding rest
+assert_equal '[0, 1, 2, [3, 4]]', %q{
+  public def lead_rest(a, b, *rest)
+    [self, a, b, rest]
+  end
+
+  def call(args) = 0.lead_rest(*args)
+
+  call([1, 2, 3, 4])
+}
+
+# test missing opts are nil initialized
+assert_equal '[[0, 1, nil, 3], [0, 1, nil, 3], [0, 1, nil, 3, []], [0, 1, nil, 3, []]]', %q{
+  public def lead_opts(a, b=binding.local_variable_get(:c), c=3)
+    [self, a, b, c]
+  end
+
+  public def opts_rest(a=raise, b=binding.local_variable_get(:c), c=3, *rest)
+    [self, a, b, c, rest]
+  end
+
+  def call(args)
+    [
+      0.lead_opts(1),
+      0.lead_opts(*args),
+
+      0.opts_rest(1),
+      0.opts_rest(*args),
+    ]
+  end
+
+  call([1])
+}
+
+# test filled optionals with unspecified keyword param
+assert_equal 'ok', %q{
+  def opt_rest_opt_kw(_=1, *, k: :ok) = k
+
+  def call = opt_rest_opt_kw(0)
+
+  call
+}
+
+# test splat empty array with rest param
+assert_equal '[0, 1, 2, []]', %q{
+  public def foo(a=1, b=2, *rest)
+    [self, a, b, rest]
+  end
+
+  def call(args) = 0.foo(*args)
+
+  call([])
+}
+
+# Regression test for yielding with autosplat to block with
+# optional parameters. https://github.com/Shopify/yjit/issues/313
+assert_equal '[:a, :b, :a, :b]', %q{
+  def yielder(arg) = yield(arg) + yield(arg)
+
+  yielder([:a, :b]) do |c = :c, d = :d|
+    [c, d]
+  end
+}
+
+# Regression test for GC mishap while doing shape transition
+assert_equal '[:ok]', %q{
+  # [Bug #19601]
+  class RegressionTest
+    def initialize
+      @a = @b = @fourth_ivar_does_shape_transition = nil
+    end
+
+    def extender
+      @first_extended_ivar = [:ok]
+    end
+  end
+
+  GC.stress = true
+
+  # Used to crash due to GC run in rb_ensure_iv_list_size()
+  # not marking the newly allocated [:ok].
+  RegressionTest.new.extender.itself
+}
+
 assert_equal 'true', %q{
   # regression test for tracking type of locals for too long
   def local_setting_cmp(five)
@@ -45,6 +360,29 @@ assert_normal_exit %q{
   Object.send(:remove_const, :Foo)
 }
 
+assert_normal_exit %q{
+  # Test to ensure send on overridden c functions
+  # doesn't corrupt the stack
+  class Bar
+    def bar(x)
+      x
+    end
+  end
+
+  class Foo
+    def bar
+      Bar.new
+    end
+  end
+
+  foo = Foo.new
+  # before this change, this line would error
+  # because "s" would still be on the stack
+  # String.to_s is the overridden method here
+  p foo.bar.bar("s".__send__(:to_s))
+}
+
+
 assert_equal '[nil, nil, nil, nil, nil, nil]', %q{
   [NilClass, TrueClass, FalseClass, Integer, Float, Symbol].each do |klass|
     klass.class_eval("def foo = @foo")
@@ -56,88 +394,77 @@ assert_equal '[nil, nil, nil, nil, nil, nil]', %q{
   end
 }
 
-assert_equal '0', %q{
-  # This is a regression test for incomplete invalidation from
-  # opt_setinlinecache. This test might be brittle, so
-  # feel free to remove it in the future if it's too annoying.
-  # This test assumes --yjit-call-threshold=2.
-  module M
-    Foo = 1
-    def foo
-      Foo
-    end
-
-    def pin_self_type_then_foo
-      _ = @foo
-      foo
-    end
-
-    def only_ints
-      1 + self
-      foo
-    end
-  end
-
-  class Integer
-    include M
+assert_equal '[nil, nil, nil, nil, nil, nil]', %q{
+  # Tests defined? on non-heap objects
+  [NilClass, TrueClass, FalseClass, Integer, Float, Symbol].each do |klass|
+    klass.class_eval("def foo = defined?(@foo)")
   end
 
-  class Sub
-    include M
+  [nil, true, false, 0xFABCAFE, 0.42, :cake].map do |instance|
+    instance.foo
+    instance.foo
   end
+}
 
-  foo_method = M.instance_method(:foo)
+assert_equal '[nil, "instance-variable", nil, "instance-variable"]', %q{
+  # defined? on object that changes shape between calls
+  class Foo
+    def foo
+      defined?(@foo)
+    end
 
-  dbg = ->(message) do
-    return # comment this out to get printouts
+    def add
+      @foo = 1
+    end
 
-    $stderr.puts RubyVM::YJIT.disasm(foo_method)
-    $stderr.puts message
+    def remove
+      self.remove_instance_variable(:@foo)
+    end
   end
 
-  2.times { 42.only_ints }
-
-  dbg["There should be two versions of getinlineache"]
-
-  module M
-    remove_const(:Foo)
-  end
+  obj = Foo.new
+  [obj.foo, (obj.add; obj.foo), (obj.remove; obj.foo), (obj.add; obj.foo)]
+}
 
-  dbg["There should be no getinlinecaches"]
+assert_equal '["instance-variable", 5]', %q{
+  # defined? on object too complex for shape information
+  class Foo
+    def initialize
+      100.times { |i| instance_variable_set("@foo#{i}", i) }
+    end
 
-  2.times do
-    42.only_ints
-  rescue NameError => err
-    _ = "caught name error #{err}"
+    def foo
+      [defined?(@foo5), @foo5]
+    end
   end
 
-  dbg["There should be one version of getinlineache"]
-
-  2.times do
-    Sub.new.pin_self_type_then_foo
-  rescue NameError
-    _ = 'second specialization'
-  end
+  Foo.new.foo
+}
 
-  dbg["There should be two versions of getinlineache"]
+# getinstancevariable with shape too complex
+assert_normal_exit %q{
+  class Foo
+    def initialize
+      @a = 1
+    end
 
-  module M
-    Foo = 1
+    def getter
+      @foobar
+    end
   end
 
-  dbg["There should still be two versions of getinlineache"]
-
-  42.only_ints
-
-  dbg["There should be no getinlinecaches"]
+  # Initialize ivars in changing order, making the Foo
+  # class have shape too complex
+  100.times do |x|
+    foo = Foo.new
+    foo.instance_variable_set(:"@a#{x}", 1)
+    foo.instance_variable_set(:"@foobar", 777)
 
-  # Find name of the first VM instruction in M#foo.
-  insns = RubyVM::InstructionSequence.of(foo_method).to_a
-  if defined?(RubyVM::YJIT.blocks_for) && (insns.last.find { Array === _1 }&.first == :opt_getinlinecache)
-    RubyVM::YJIT.blocks_for(RubyVM::InstructionSequence.of(foo_method))
-      .filter { _1.iseq_start_index == 0 }.count
-  else
-    0 # skip the test
+    # The getter method eventually sees shape too complex
+    r = foo.getter
+    if r != 777
+      raise "error"
+    end
   end
 }
 
@@ -198,6 +525,8 @@ assert_equal 'string', %q{
 
 # Check that exceptions work when getting global variable
 assert_equal 'rescued', %q{
+  Warning[:deprecated] = true
+
   module Warning
     def warn(message)
       raise
@@ -351,6 +680,45 @@ assert_equal 'false', %q{
   less_than 2
 }
 
+# BOP redefinition works on Integer#<=
+assert_equal 'false', %q{
+  def le(x, y) = x <= y
+
+  le(2, 2)
+
+  class Integer
+    def <=(_) = false
+  end
+
+  le(2, 2)
+}
+
+# BOP redefinition works on Integer#>
+assert_equal 'false', %q{
+  def gt(x, y) = x > y
+
+  gt(3, 2)
+
+  class Integer
+    def >(_) = false
+  end
+
+  gt(3, 2)
+}
+
+# BOP redefinition works on Integer#>=
+assert_equal 'false', %q{
+  def ge(x, y) = x >= y
+
+  ge(2, 2)
+
+  class Integer
+    def >=(_) = false
+  end
+
+  ge(2, 2)
+}
+
 # Putobject, less-than operator, fixnums
 assert_equal '2', %q{
     def check_index(index)
@@ -794,6 +1162,7 @@ assert_equal 'special', %q{
 
 # Test that object references in generated code get marked and moved
 assert_equal "good", %q{
+  skip :good unless GC.respond_to?(:compact)
   def bar
     "good"
   end
@@ -817,7 +1186,7 @@ assert_equal "good", %q{
 # Test polymorphic getinstancevariable. T_OBJECT -> T_STRING
 assert_equal 'ok', %q{
   @hello = @h1 = @h2 = @h3 = @h4 = 'ok'
-  str = ""
+  str = +""
   str.instance_variable_set(:@hello, 'ok')
 
   public def get
@@ -961,6 +1330,18 @@ assert_equal '[42, :default]', %q{
   ]
 }
 
+# Test default value block for Hash
+assert_equal "false", <<~RUBY, frozen_string_literal: false
+  def index_with_string(h)
+    h["foo"]
+  end
+
+  h = Hash.new { |h, k| k.frozen? }
+
+  index_with_string(h)
+  index_with_string(h)
+RUBY
+
 # A regression test for making sure cfp->sp is proper when
 # hitting stubs. See :stub-sp-flush:
 assert_equal 'ok', %q{
@@ -1118,6 +1499,38 @@ assert_equal '42', %q{
   run
 }
 
+# splatting an empty array on a specialized method
+assert_equal 'ok', %q{
+  def run
+    "ok".to_s(*[])
+  end
+
+  run
+  run
+}
+
+# splatting an single element array on a specialized method
+assert_equal '[1]', %q{
+  def run
+    [].<<(*[1])
+  end
+
+  run
+  run
+}
+
+# specialized method with wrong args
+assert_equal 'ok', %q{
+  def run(x)
+    "bad".to_s(123) if x
+  rescue
+    :ok
+  end
+
+  run(false)
+  run(true)
+}
+
 # getinstancevariable on Symbol
 assert_equal '[nil, nil]', %q{
   # @foo to exercise the getinstancevariable instruction
@@ -1317,7 +1730,7 @@ assert_equal '{}', %q{
 }
 
 # test building hash with values
-assert_equal '{:foo=>:bar}', %q{
+assert_equal '{foo: :bar}', %q{
   def build_hash(val)
     { foo: val }
   end
@@ -1427,7 +1840,7 @@ assert_equal 'foo', %q{
 }
 
 # Test that String unary plus returns the same object ID for an unfrozen string.
-assert_equal 'true', %q{
+assert_equal 'true', <<~RUBY, frozen_string_literal: false
   def jittable_method
     str = "bar"
 
@@ -1437,7 +1850,7 @@ assert_equal 'true', %q{
     uplus_str.object_id == old_obj_id
   end
   jittable_method
-}
+RUBY
 
 # Test that String unary plus returns a different unfrozen string when given a frozen string
 assert_equal 'false', %q{
@@ -1551,6 +1964,85 @@ assert_equal 'true', %q{
   jittable_method
 }
 
+# test getbyte on string class
+assert_equal '[97, :nil, 97, :nil, :raised]', %q{
+  def getbyte(s, i)
+   byte = begin
+    s.getbyte(i)
+   rescue TypeError
+    :raised
+   end
+
+   byte || :nil
+  end
+
+  getbyte("a", 0)
+  getbyte("a", 0)
+
+  [getbyte("a", 0), getbyte("a", 1), getbyte("a", -1), getbyte("a", -2), getbyte("a", "a")]
+}
+
+# Basic test for String#setbyte
+assert_equal 'AoZ', %q{
+  s = +"foo"
+  s.setbyte(0, 65)
+  s.setbyte(-1, 90)
+  s
+}
+
+# String#setbyte IndexError
+assert_equal 'String#setbyte', %q{
+  def ccall = "".setbyte(1, 0)
+  begin
+    ccall
+  rescue => e
+    e.backtrace.first.split("'").last
+  end
+}
+
+# String#setbyte TypeError
+assert_equal 'String#setbyte', %q{
+  def ccall = "".setbyte(nil, 0)
+  begin
+    ccall
+  rescue => e
+    e.backtrace.first.split("'").last
+  end
+}
+
+# String#setbyte FrozenError
+assert_equal 'String#setbyte', %q{
+  def ccall = "a".freeze.setbyte(0, 0)
+  begin
+    ccall
+  rescue => e
+    e.backtrace.first.split("'").last
+  end
+}
+
+# non-leaf String#setbyte
+assert_equal 'String#setbyte', %q{
+  def to_int
+    @caller = caller
+    0
+  end
+
+  def ccall = "a".dup.setbyte(self, 98)
+  ccall
+
+  @caller.first.split("'").last
+}
+
+# non-leaf String#byteslice
+assert_equal 'TypeError', %q{
+  def ccall = "".byteslice(nil, nil)
+  begin
+    ccall
+  rescue => e
+    e.class
+  end
+}
+
 # Test << operator on string subclass
 assert_equal 'abab', %q{
   class MyString < String; end
@@ -1696,6 +2188,34 @@ assert_equal '7', %q{
   foo(5,2)
 }
 
+# regression test for argument registers with invalidation
+assert_equal '[0, 1, 2]', %q{
+  def test(n)
+    ret = n
+    binding
+    ret
+  end
+
+  [0, 1, 2].map do |n|
+    test(n)
+  end
+}
+
+# regression test for argument registers
+assert_equal 'true', %q{
+  class Foo
+    def ==(other)
+      other == nil
+    end
+  end
+
+  def test
+    [Foo.new].include?(Foo.new)
+  end
+
+  test
+}
+
 # test pattern matching
 assert_equal '[:ok, :ok]', %q{
   class C
@@ -1761,6 +2281,20 @@ assert_equal '123', %q{
   foo(Foo)
 }
 
+# Test EP == BP invalidation with moving ISEQs
+assert_equal 'ok', %q{
+  skip :ok unless GC.respond_to?(:compact)
+  def entry
+    ok = proc { :ok } # set #entry as an EP-escaping ISEQ
+    [nil].reverse_each do # avoid exiting the JIT frame on the constant
+      GC.compact # move #entry ISEQ
+    end
+    ok # should be read off of escaped EP
+  end
+
+  entry.call
+}
+
 # invokesuper edge case
 assert_equal '[:A, [:A, :B]]', %q{
   class B
@@ -1917,6 +2451,50 @@ assert_equal '[:A, :Btwo]', %q{
   ins.foo
 }
 
+# invokesuper with a block
+assert_equal 'true', %q{
+  class A
+    def foo = block_given?
+  end
+
+  class B < A
+    def foo = super()
+  end
+
+  B.new.foo { }
+  B.new.foo { }
+}
+
+# invokesuper in a block
+assert_equal '[0, 2]', %q{
+  class A
+    def foo(x) = x * 2
+  end
+
+  class B < A
+    def foo
+      2.times.map do |x|
+        super(x)
+      end
+    end
+  end
+
+  B.new.foo
+  B.new.foo
+}
+
+# invokesuper zsuper in a bmethod
+assert_equal 'ok', %q{
+  class Foo
+    define_method(:itself) { super }
+  end
+  begin
+    Foo.new.itself
+  rescue RuntimeError
+    :ok
+  end
+}
+
 # Call to fixnum
 assert_equal '[true, false]', %q{
   def is_odd(obj)
@@ -1957,6 +2535,16 @@ assert_equal '[true, false, true, false]', %q{
   [is_odd(123), is_odd(456), is_odd(bignum), is_odd(bignum+1)]
 }
 
+# Flonum and Flonum
+assert_equal '[2.0, 0.0, 1.0, 4.0]', %q{
+  [1.0 + 1.0, 1.0 - 1.0, 1.0 * 1.0, 8.0 / 2.0]
+}
+
+# Flonum and Fixnum
+assert_equal '[2.0, 0.0, 1.0, 4.0]', %q{
+  [1.0 + 1, 1.0 - 1, 1.0 * 1, 8.0 / 2]
+}
+
 # Call to static and dynamic symbol
 assert_equal 'bar', %q{
   def to_string(obj)
@@ -1997,6 +2585,30 @@ assert_equal '[1, 2, 3, 4, 5]', %q{
   splatarray
 }
 
+# splatkw
+assert_equal '[1, 2]', %q{
+  def foo(a:) = [a, yield]
+
+  def entry(&block)
+    a = { a: 1 }
+    foo(**a, &block)
+  end
+
+  entry { 2 }
+}
+assert_equal '[1, 2]', %q{
+  def foo(a:) = [a, yield]
+
+  def entry(obj, &block)
+    foo(**obj, &block)
+  end
+
+  entry({ a: 3 }) { 2 }
+  obj = Object.new
+  def obj.to_hash = { a: 1 }
+  entry(obj) { 2 }
+}
+
 assert_equal '[1, 1, 2, 1, 2, 3]', %q{
   def expandarray
     arr = [1, 2, 3]
@@ -2051,6 +2663,39 @@ assert_equal '[:not_array, nil, nil]', %q{
   expandarray_not_array(obj)
 }
 
+assert_equal '[1, 2]', %q{
+  class NilClass
+    private
+    def to_ary
+      [1, 2]
+    end
+  end
+
+  def expandarray_redefined_nilclass
+    a, b = nil
+    [a, b]
+  end
+
+  expandarray_redefined_nilclass
+  expandarray_redefined_nilclass
+}
+
+assert_equal 'not_array', %q{
+  def expandarray_not_array(obj)
+    a, = obj
+    a
+  end
+
+  obj = Object.new
+  def obj.method_missing(m, *args, &block)
+    return [:not_array] if m == :to_ary
+    super
+  end
+
+  expandarray_not_array(obj)
+  expandarray_not_array(obj)
+}
+
 assert_equal '[1, 2, nil]', %q{
   def expandarray_rhs_too_small
     a, b, c = [1, 2]
@@ -2061,6 +2706,17 @@ assert_equal '[1, 2, nil]', %q{
   expandarray_rhs_too_small
 }
 
+assert_equal '[nil, 2, nil]', %q{
+  def foo(arr)
+    a, b, c = arr
+  end
+
+  a, b, c1 = foo([0, 1])
+  a, b, c2 = foo([0, 1, 2])
+  a, b, c3 = foo([0, 1])
+  [c1, c2, c3]
+}
+
 assert_equal '[1, [2]]', %q{
   def expandarray_splat
     a, *b = [1, 2]
@@ -2249,6 +2905,26 @@ assert_equal '[[:c_return, :itself, main]]', %q{
   events
 }
 
+# test c_call invalidation
+assert_equal '[[:c_call, :itself]]', %q{
+  # enable the event once to make sure invalidation
+  # happens the second time we enable it
+  TracePoint.new(:c_call) {}.enable{}
+
+  def compiled
+    itself
+  end
+
+  # assume first call compiles
+  compiled
+
+  events = []
+  tp = TracePoint.new(:c_call) { |tp| events << [tp.event, tp.method_id] }
+  tp.enable { compiled }
+
+  events
+}
+
 # test enabling tracing for a suspended fiber
 assert_equal '[[:return, 42]]', %q{
   def traced_method
@@ -2273,15 +2949,16 @@ assert_equal '[:itself]', %q{
     itself
   end
 
-  tracing_ractor = Ractor.new do
+  port = Ractor::Port.new
+  tracing_ractor = Ractor.new port do |port|
     # 1: start tracing
     events = []
     tp = TracePoint.new(:c_call) { events << _1.method_id }
     tp.enable
-    Ractor.yield(nil)
+    port << nil
 
     # 3: run compiled method on tracing ractor
-    Ractor.yield(nil)
+    port << nil
     traced_method
 
     events
@@ -2289,13 +2966,13 @@ assert_equal '[:itself]', %q{
     tp&.disable
   end
 
-  tracing_ractor.take
+  port.receive
 
   # 2: compile on non tracing ractor
   traced_method
 
-  tracing_ractor.take
-  tracing_ractor.take
+  port.receive
+  tracing_ractor.value
 }
 
 # Try to hit a lazy branch stub while another ractor enables tracing
@@ -2309,17 +2986,18 @@ assert_equal '42', %q{
     end
   end
 
-  ractor = Ractor.new do
+  port = Ractor::Port.new
+  ractor = Ractor.new port do |port|
     compiled(false)
-    Ractor.yield(nil)
+    port << nil
     compiled(41)
   end
 
   tp = TracePoint.new(:line) { itself }
-  ractor.take
+  port.receive
   tp.enable
 
-  ractor.take
+  ractor.value
 }
 
 # Test equality with changing types
@@ -2395,7 +3073,7 @@ assert_equal '42',  %q{
   A.foo
   A.foo
 
-  Ractor.new { A.foo }.take
+  Ractor.new { A.foo }.value
 }
 
 assert_equal '["plain", "special", "sub", "plain"]', %q{
@@ -2647,7 +3325,7 @@ assert_equal '[[1, 2, 3, 4]]', %q{
 }
 
 # cfunc kwargs
-assert_equal '{:foo=>123}', %q{
+assert_equal '{foo: 123}', %q{
   def foo(bar)
     bar.store(:value, foo: 123)
     bar[:value]
@@ -2658,7 +3336,7 @@ assert_equal '{:foo=>123}', %q{
 }
 
 # cfunc kwargs
-assert_equal '{:foo=>123}', %q{
+assert_equal '{foo: 123}', %q{
   def foo(bar)
     bar.replace(foo: 123)
   end
@@ -2668,7 +3346,7 @@ assert_equal '{:foo=>123}', %q{
 }
 
 # cfunc kwargs
-assert_equal '{:foo=>123, :bar=>456}', %q{
+assert_equal '{foo: 123, bar: 456}', %q{
   def foo(bar)
     bar.replace(foo: 123, bar: 456)
   end
@@ -2678,7 +3356,7 @@ assert_equal '{:foo=>123, :bar=>456}', %q{
 }
 
 # variadic cfunc kwargs
-assert_equal '{:foo=>123}', %q{
+assert_equal '{foo: 123}', %q{
   def foo(bar)
     bar.merge(foo: 123)
   end
@@ -2802,7 +3480,7 @@ assert_equal "true", %q{
 }
 
 # duphash
-assert_equal '{:foo=>123}', %q{
+assert_equal '{foo: 123}', %q{
   def foo
     {foo: 123}
   end
@@ -2812,7 +3490,7 @@ assert_equal '{:foo=>123}', %q{
 }
 
 # newhash
-assert_equal '{:foo=>2}', %q{
+assert_equal '{foo: 2}', %q{
   def foo
     {foo: 1+1}
   end
@@ -2922,6 +3600,74 @@ assert_equal 'new', %q{
   test
 }
 
+# Bug #21257 (infinite jmp)
+assert_equal 'ok', %q{
+  Good = :ok
+
+  def first
+    second
+  end
+
+  def second
+    ::Good
+  end
+
+  # Make `second` side exit on its first instruction
+  trace = TracePoint.new(:line) { }
+  trace.enable(target: method(:second))
+
+  first
+  # Recompile now that the constant cache is populated, so we get a fallthrough from `first` to `second`
+  # (this is need to reproduce with --yjit-call-threshold=1)
+  RubyVM::YJIT.code_gc if defined?(RubyVM::YJIT)
+  first
+
+  # Trigger a constant cache miss in rb_vm_opt_getconstant_path (in `second`) next time it's called
+  module InvalidateConstantCache
+    Good = nil
+  end
+
+  RubyVM::YJIT.simulate_oom! if defined?(RubyVM::YJIT)
+
+  first
+  first
+}
+
+assert_equal 'ok', %q{
+  # Multiple incoming branches into second
+  Good = :ok
+
+  def incoming_one
+    second
+  end
+
+  def incoming_two
+    second
+  end
+
+  def second
+    ::Good
+  end
+
+  # Make `second` side exit on its first instruction
+  trace = TracePoint.new(:line) { }
+  trace.enable(target: method(:second))
+
+  incoming_one
+  # Recompile now that the constant cache is populated, so we get a fallthrough from `incoming_one` to `second`
+  # (this is need to reproduce with --yjit-call-threshold=1)
+  RubyVM::YJIT.code_gc if defined?(RubyVM::YJIT)
+  incoming_one
+  incoming_two
+
+  # Trigger a constant cache miss in rb_vm_opt_getconstant_path (in `second`) next time it's called
+  module InvalidateConstantCache
+    Good = nil
+  end
+
+  incoming_one
+}
+
 assert_equal 'ok', %q{
   # Try to compile new method while OOM
   def foo
@@ -3046,36 +3792,6 @@ assert_equal '3,12', %q{
   pt_inspect(p)
 }
 
-# Regression test for deadlock between branch_stub_hit and ractor_receive_if
-assert_equal '10', %q{
-  r = Ractor.new Ractor.current do |main|
-    main << 1
-    main << 2
-    main << 3
-    main << 4
-    main << 5
-    main << 6
-    main << 7
-    main << 8
-    main << 9
-    main << 10
-  end
-
-  a = []
-  a << Ractor.receive_if{|msg| msg == 10}
-  a << Ractor.receive_if{|msg| msg == 9}
-  a << Ractor.receive_if{|msg| msg == 8}
-  a << Ractor.receive_if{|msg| msg == 7}
-  a << Ractor.receive_if{|msg| msg == 6}
-  a << Ractor.receive_if{|msg| msg == 5}
-  a << Ractor.receive_if{|msg| msg == 4}
-  a << Ractor.receive_if{|msg| msg == 3}
-  a << Ractor.receive_if{|msg| msg == 2}
-  a << Ractor.receive_if{|msg| msg == 1}
-
-  a.length
-}
-
 # checktype
 assert_equal 'false', %q{
     def function()
@@ -3309,3 +4025,1438 @@ assert_equal 'true', %q{
   end
   foo(Foo.new)
 }
+
+# bmethod
+assert_equal '[1, 2, 3]', %q{
+  one = 1
+  define_method(:foo) do
+    one
+  end
+
+  3.times.map { |i| foo + i }
+}
+
+# return inside bmethod
+assert_equal 'ok', %q{
+  define_method(:foo) do
+    1.tap { return :ok }
+  end
+
+  foo
+}
+
+# bmethod optional and keywords
+assert_equal '[[1, nil, 2]]', %q{
+  define_method(:opt_and_kwargs) do |a = {}, b: nil, c: nil|
+    [a, b, c]
+  end
+
+  5.times.map { opt_and_kwargs(1, c: 2) }.uniq
+}
+
+# bmethod with forwarded block
+assert_equal '2', %q{
+  define_method(:foo) do |&block|
+    block.call
+  end
+
+  def bar(&block)
+    foo(&block)
+  end
+
+  bar { 1 }
+  bar { 2 }
+}
+
+# bmethod with forwarded block and arguments
+assert_equal '5', %q{
+  define_method(:foo) do |n, &block|
+    n + block.call
+  end
+
+  def bar(n, &block)
+    foo(n, &block)
+  end
+
+  bar(0) { 1 }
+  bar(3) { 2 }
+}
+
+# bmethod with forwarded unwanted block
+assert_equal '1', %q{
+  one = 1
+  define_method(:foo) do
+    one
+  end
+
+  def bar(&block)
+    foo(&block)
+  end
+
+  bar { }
+  bar { }
+}
+
+# unshareable bmethod call through Method#to_proc#call
+assert_equal '1000', %q{
+  define_method(:bmethod) do
+    self
+  end
+
+  Ractor.new do
+    errors = 0
+    1000.times do
+      p = method(:bmethod).to_proc
+      begin
+        p.call
+      rescue RuntimeError
+        errors += 1
+      end
+    end
+    errors
+  end.value
+}
+
+# test for return stub lifetime issue
+assert_equal '1', %q{
+  def foo(n)
+    if n == 2
+      return 1.times { Object.define_method(:foo) {} }
+    end
+
+    foo(n + 1)
+  end
+
+  foo(1)
+}
+
+# case-when with redefined ===
+assert_equal 'ok', %q{
+  class Symbol
+    def ===(a)
+      true
+    end
+  end
+
+  def cw(arg)
+    case arg
+    when :b
+      :ok
+    when 4
+      :ng
+    end
+  end
+
+  cw(4)
+}
+
+assert_equal 'threw', %q{
+  def foo(args)
+    wrap(*args)
+  rescue ArgumentError
+    'threw'
+  end
+
+  def wrap(a)
+    [a]
+  end
+
+  foo([Hash.ruby2_keywords_hash({})])
+}
+
+assert_equal 'threw', %q{
+  # C call
+  def bar(args)
+    Array(*args)
+  rescue ArgumentError
+    'threw'
+  end
+
+  bar([Hash.ruby2_keywords_hash({})])
+}
+
+# Test instance_of? and is_a?
+assert_equal 'true', %q{
+  1.instance_of?(Integer) && 1.is_a?(Integer)
+}
+
+# Test instance_of? and is_a? for singleton classes
+assert_equal 'true', %q{
+  a = []
+  def a.test = :test
+  a.instance_of?(Array) && a.is_a?(Array)
+}
+
+# Test instance_of? for singleton_class
+# Yes this does really return false
+assert_equal 'false', %q{
+  a = []
+  def a.test = :test
+  a.instance_of?(a.singleton_class)
+}
+
+# Test is_a? for singleton_class
+assert_equal 'true', %q{
+  a = []
+  def a.test = :test
+  a.is_a?(a.singleton_class)
+}
+
+# Test send with splat to a cfunc
+assert_equal 'true', %q{
+  1.send(:==, 1, *[])
+}
+
+# Test empty splat with cfunc
+assert_equal '2', %q{
+  def foo
+    Integer.sqrt(4, *[])
+  end
+  # call twice to deal with constant exiting
+  foo
+  foo
+}
+
+# Test non-empty splat with cfunc
+assert_equal 'Hello World', %q{
+  def bar
+    args = ["Hello "]
+    greeting = +"World"
+    greeting.insert(0, *args)
+    greeting
+  end
+  bar
+}
+
+# Regression: this creates a temp stack with > 127 elements
+assert_normal_exit %q{
+  def foo(a)
+    [
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a, a, a,
+      a, a, a, a, a, a, a, a,
+    ]
+  end
+
+  def entry
+    foo(1)
+  end
+
+  entry
+}
+
+# Test that splat and rest combined
+# properly dupe the array
+assert_equal "[]", %q{
+  def foo(*rest)
+    rest << 1
+  end
+
+  def test(splat)
+    foo(*splat)
+  end
+
+  EMPTY = []
+  custom = Object.new
+  def custom.to_a
+    EMPTY
+  end
+
+  test(custom)
+  test(custom)
+  EMPTY
+}
+
+# Rest with send
+assert_equal '[1, 2, 3]', %q{
+  def bar(x, *rest)
+    rest.insert(0, x)
+  end
+  send(:bar, 1, 2, 3)
+}
+
+# Fix splat block arg bad compilation
+assert_equal "foo", %q{
+  def literal(*args, &block)
+    s = ''.dup
+    literal_append(s, *args, &block)
+    s
+  end
+
+  def literal_append(sql, v)
+    sql << v
+  end
+
+  literal("foo")
+}
+
+# regression test for accidentally having a parameter truncated
+# due to Rust/C signature mismatch. Used to crash with
+# > [BUG] rb_vm_insn_addr2insn: invalid insn address ...
+# or
+# > ... `Err` value: TryFromIntError(())'
+assert_normal_exit %q{
+  n = 16384
+  eval(
+    "def foo(arg); " + "_=arg;" * n + '_=1;' + "Object; end"
+  )
+  foo 1
+}
+
+# Regression test for CantCompile not using starting_ctx
+assert_normal_exit %q{
+  class Integer
+    def ===(other)
+      false
+    end
+  end
+
+  def my_func(x)
+    case x
+    when 1
+      1
+    when 2
+      2
+    else
+      3
+    end
+  end
+
+  my_func(1)
+}
+
+# Regression test for CantCompile not using starting_ctx
+assert_equal "ArgumentError", %q{
+  def literal(*args, &block)
+    s = ''.dup
+    args = [1, 2, 3]
+    literal_append(s, *args, &block)
+    s
+  end
+
+  def literal_append(sql, v)
+    [sql.inspect, v.inspect]
+  end
+
+  begin
+    literal("foo")
+  rescue ArgumentError
+    "ArgumentError"
+  end
+}
+
+# Rest with block
+# Simplified code from railsbench
+assert_equal '[{"/a" => "b", as: :c, via: :post}, [], nil]', %q{
+  def match(path, *rest, &block)
+    [path, rest, block]
+  end
+
+  def map_method(method, args, &block)
+    options = args.last
+    args.pop
+    options[:via] = method
+    match(*args, options, &block)
+  end
+
+  def post(*args, &block)
+    map_method(:post, args, &block)
+  end
+
+  post "/a" => "b", as: :c
+}
+
+# Test rest and kw_args
+assert_equal '[true, true, true, true]', %q{
+  def my_func(*args, base: nil, sort: true)
+    [args, base, sort]
+  end
+
+  def calling_my_func
+    results = []
+    results << (my_func("test") == [["test"], nil, true])
+    results << (my_func("test", base: :base) == [["test"], :base, true])
+    results << (my_func("test", sort: false) == [["test"], nil, false])
+    results << (my_func("test", "other", base: :base) == [["test", "other"], :base, true])
+    results
+  end
+  calling_my_func
+}
+
+# Test Integer#[] with 2 args
+assert_equal '0', %q{
+  3[0, 0]
+}
+
+# unspecified_bits + checkkeyword
+assert_equal '2', %q{
+  def callee = 1
+
+  # checkkeyword should see unspecified_bits=0 (use bar), not Integer 1 (set bar = foo).
+  def foo(foo, bar: foo) = bar
+
+  def entry(&block)
+    # write 1 at stack[3]. Calling #callee spills stack[3].
+    1 + (1 + (1 + (1 + callee)))
+    # &block is written to a register instead of stack[3]. When &block is popped and
+    # unspecified_bits is pushed, it must be written to stack[3], not to a register.
+    foo(1, bar: 2, &block)
+  end
+
+  entry # call branch_stub_hit (spill temps)
+  entry # doesn't call branch_stub_hit (not spill temps)
+}
+
+# Test rest and optional_params
+assert_equal '[true, true, true, true]', %q{
+  def my_func(stuff, base=nil, sort=true, *args)
+    [stuff, base, sort, args]
+  end
+
+  def calling_my_func
+    results = []
+    results << (my_func("test") == ["test", nil, true, []])
+    results << (my_func("test", :base) == ["test", :base, true, []])
+    results << (my_func("test", :base, false) == ["test", :base, false, []])
+    results << (my_func("test", :base, false, "other", "other") == ["test", :base, false, ["other", "other"]])
+    results
+  end
+  calling_my_func
+}
+
+# Test rest and optional_params and splat
+assert_equal '[true, true, true, true, true]', %q{
+  def my_func(stuff, base=nil, sort=true, *args)
+    [stuff, base, sort, args]
+  end
+
+  def calling_my_func
+    results = []
+    splat = ["test"]
+    results << (my_func(*splat) == ["test", nil, true, []])
+    splat = [:base]
+    results << (my_func("test", *splat) == ["test", :base, true, []])
+    splat = [:base, false]
+    results << (my_func("test", *splat) == ["test", :base, false, []])
+    splat = [:base, false, "other", "other"]
+    results << (my_func("test", *splat) == ["test", :base, false, ["other", "other"]])
+    splat = ["test", :base, false, "other", "other"]
+    results << (my_func(*splat) == ["test", :base, false, ["other", "other"]])
+    results
+  end
+  calling_my_func
+}
+
+# Regression test: rest and optional and splat
+assert_equal 'true', %q{
+  def my_func(base=nil, *args)
+    [base, args]
+  end
+
+  def calling_my_func
+    array = []
+    my_func(:base, :rest1, *array) == [:base, [:rest1]]
+  end
+
+  calling_my_func
+}
+
+# Fix failed case for large splat
+assert_equal 'true', %q{
+  def d(a, b=:b)
+  end
+
+  def calling_func
+    ary = 1380888.times;
+    d(*ary)
+  end
+  begin
+    calling_func
+  rescue ArgumentError
+    true
+  end
+}
+
+# Regression test: register allocator on expandarray
+assert_equal '[]', %q{
+  func = proc { [] }
+  proc do
+    _x, _y = func.call
+  end.call
+}
+
+# Catch TAG_BREAK in a non-FINISH frame with JIT code
+assert_equal '1', %q{
+  def entry
+    catch_break
+  end
+
+  def catch_break
+    while_true do
+      break
+    end
+    1
+  end
+
+  def while_true
+    while true
+      yield
+    end
+  end
+
+  entry
+}
+
+assert_equal '6', %q{
+  class Base
+    def number = 1 + yield
+  end
+
+  class Sub < Base
+    def number = super + 2
+  end
+
+  Sub.new.number { 3 }
+}
+
+# Integer multiplication and overflow
+assert_equal '[6, -6, 9671406556917033397649408, -9671406556917033397649408, 21267647932558653966460912964485513216]', %q{
+  def foo(a, b)
+    a * b
+  end
+
+  r1 = foo(2, 3)
+  r2 = foo(2, -3)
+  r3 = foo(2 << 40, 2 << 41)
+  r4 = foo(2 << 40, -2 << 41)
+  r5 = foo(1 << 62, 1 << 62)
+
+  [r1, r2, r3, r4, r5]
+}
+
+# Integer multiplication and overflow (minimized regression test from test-basic)
+assert_equal '8515157028618240000', %q{2128789257154560000 * 4}
+
+# Inlined method calls
+assert_equal 'nil', %q{
+  def putnil = nil
+  def entry = putnil
+  entry.inspect
+}
+assert_equal '1', %q{
+  def putobject_1 = 1
+  def entry = putobject_1
+  entry
+}
+assert_equal 'false', %q{
+  def putobject(_unused_arg1) = false
+  def entry = putobject(nil)
+  entry
+}
+assert_equal 'true', %q{
+  def entry = yield
+  entry { true }
+}
+assert_equal 'sym', %q{
+  def entry = :sym.to_sym
+  entry
+}
+
+assert_normal_exit %q{
+  ivars = 1024.times.map { |i| "@iv_#{i} = #{i}\n" }.join
+  Foo = Class.new
+  Foo.class_eval "def initialize() #{ivars} end"
+  Foo.new
+}
+
+assert_equal '0', %q{
+  def spill
+    1.to_i # not inlined
+  end
+
+  def inline(_stack1, _stack2, _stack3, _stack4, _stack5)
+    0 # inlined
+  end
+
+  def entry
+    # RegTemps is 00111110 prior to the #inline call.
+    # Its return value goes to stack_idx=0, which conflicts with stack_idx=5.
+    inline(spill, 2, 3, 4, 5)
+  end
+
+  entry
+}
+
+# Integer succ and overflow
+assert_equal '[2, 4611686018427387904]', %q{
+  [1.succ, 4611686018427387903.succ]
+}
+
+# Integer pred and overflow
+assert_equal '[0, -4611686018427387905]', %q{
+  [1.pred, -4611686018427387904.pred]
+}
+
+# Integer right shift
+assert_equal '[0, 1, -4]', %q{
+  [0 >> 1, 2 >> 1, -7 >> 1]
+}
+
+# Integer XOR
+assert_equal '[0, 0, 4]', %q{
+  [0 ^ 0, 1 ^ 1, 7 ^ 3]
+}
+
+assert_equal '[nil, "yield"]', %q{
+  def defined_yield = defined?(yield)
+  [defined_yield, defined_yield {}]
+}
+
+# splat with ruby2_keywords into rest parameter
+assert_equal '[[{a: 1}], {}]', %q{
+  ruby2_keywords def foo(*args) = args
+
+  def bar(*args, **kw) = [args, kw]
+
+  def pass_bar(*args) = bar(*args)
+
+  def body
+    args = foo(a: 1)
+    pass_bar(*args)
+  end
+
+  body
+}
+
+# concatarray
+assert_equal '[1, 2]', %q{
+  def foo(a, b) = [a, b]
+  arr = [2]
+  foo(*[1], *arr)
+}
+
+# pushtoarray
+assert_equal '[1, 2]', %q{
+  def foo(a, b) = [a, b]
+  arr = [1]
+  foo(*arr, 2)
+}
+
+# pop before fallback
+assert_normal_exit %q{
+  class Foo
+    attr_reader :foo
+
+    def try = foo(0, &nil)
+  end
+
+  Foo.new.try
+}
+
+# a kwrest case
+assert_equal '[1, 2, {complete: false}]', %q{
+  def rest(foo: 1, bar: 2, **kwrest)
+    [foo, bar, kwrest]
+  end
+
+  def callsite = rest(complete: false)
+
+  callsite
+}
+
+# splat+kw_splat+opt+rest
+assert_equal '[1, []]', %q{
+  def opt_rest(a = 0, *rest) = [a, rest]
+
+  def call_site(args) = opt_rest(*args, **nil)
+
+  call_site([1])
+}
+
+# splat and nil kw_splat
+assert_equal 'ok', %q{
+  def identity(x) = x
+
+  def splat_nil_kw_splat(args) = identity(*args, **nil)
+
+  splat_nil_kw_splat([:ok])
+}
+
+# empty splat and kwsplat into leaf builtins
+assert_equal '[1, 1, 1]', %q{
+  empty = []
+  [1.abs(*empty), 1.abs(**nil), 1.bit_length(*empty, **nil)]
+}
+
+# splat into C methods with -1 arity
+assert_equal '[[1, 2, 3], [0, 2, 3], [1, 2, 3], [2, 2, 3], [], [], [{}]]', %q{
+  class Foo < Array
+    def push(args) = super(1, *args)
+  end
+
+  def test_cfunc_vargs_splat(sub_instance, array_class, empty_kw_hash)
+    splat = [2, 3]
+    kw_splat = [empty_kw_hash]
+    [
+      sub_instance.push(splat),
+      array_class[0, *splat, **nil],
+      array_class[1, *splat, &nil],
+      array_class[2, *splat, **nil, &nil],
+      array_class.send(:[], *kw_splat),
+      # kw_splat disables keywords hash handling
+      array_class[*kw_splat],
+      array_class[*kw_splat, **nil],
+    ]
+  end
+
+  test_cfunc_vargs_splat(Foo.new, Array, Hash.ruby2_keywords_hash({}))
+}
+
+# Class#new (arity=-1), splat, and ruby2_keywords
+assert_equal '[0, {1 => 1}]', %q{
+  class KwInit
+    attr_reader :init_args
+    def initialize(x = 0, **kw)
+      @init_args = [x, kw]
+    end
+  end
+
+  def test(klass, args)
+    klass.new(*args).init_args
+  end
+
+  test(KwInit, [Hash.ruby2_keywords_hash({1 => 1})])
+}
+
+# Chilled string setivar trigger warning
+assert_match(/literal string will be frozen in the future/, %q{
+  Warning[:deprecated] = true
+  $VERBOSE = true
+  $warning = "no-warning"
+  module ::Warning
+    def self.warn(message)
+      $warning = message.split("warning: ").last.strip
+    end
+  end
+
+  class String
+    def setivar!
+      @ivar = 42
+    end
+  end
+
+  def setivar!(str)
+    str.setivar!
+  end
+
+  10.times { setivar!("mutable".dup) }
+  10.times do
+    setivar!("frozen".freeze)
+  rescue FrozenError
+  end
+
+  setivar!("chilled") # Emit warning
+  $warning
+})
+
+# arity=-2 cfuncs
+assert_equal '["", "1/2", [0, [:ok, 1]]]', %q{
+  def test_cases(file, chain)
+    new_chain = chain.allocate # to call initialize directly
+    new_chain.send(:initialize, [0], ok: 1)
+
+    [
+      file.join,
+      file.join("1", "2"),
+      new_chain.to_a,
+    ]
+  end
+
+  test_cases(File, Enumerator::Chain)
+}
+
+# singleton class should invalidate Type::CString assumption
+assert_equal 'foo', %q{
+  def define_singleton(str, define)
+    if define
+      # Wrap a C method frame to avoid exiting JIT code on defineclass
+      [nil].reverse_each do
+        class << str
+          def +(_)
+            "foo"
+          end
+        end
+      end
+    end
+    "bar"
+  end
+
+  def entry(define)
+    str = ""
+    # When `define` is false, #+ compiles to rb_str_plus() without a class guard.
+    # When the code is reused with `define` is true, the class of `str` is changed
+    # to a singleton class, so the block should be invalidated.
+    str + define_singleton(str, define)
+  end
+
+  entry(false)
+  entry(true)
+}
+
+assert_equal 'ok', %q{
+  def ok
+    :ok
+  end
+
+  def delegator(...)
+    ok(...)
+  end
+
+  def caller
+    send(:delegator)
+  end
+
+  caller
+}
+
+# test inlining of simple iseqs
+assert_equal '[:ok, :ok, :ok]', %q{
+  def identity(x) = x
+  def foo(x, _) = x
+  def bar(_, _, _, _, x) = x
+
+  def tests
+    [
+      identity(:ok),
+      foo(:ok, 2),
+      bar(1, 2, 3, 4, :ok),
+    ]
+  end
+
+  tests
+}
+
+# test inlining of simple iseqs with kwargs
+assert_equal '[:ok, :ok, :ok, :ok, :ok]', %q{
+  def optional_unused(x, opt: :not_ok) = x
+  def optional_used(x, opt: :ok) = opt
+  def required_unused(x, req:) = x
+  def required_used(x, req:) = req
+  def unknown(x) = x
+
+  def tests
+    [
+      optional_unused(:ok),
+      optional_used(:not_ok),
+      required_unused(:ok, req: :not_ok),
+      required_used(:not_ok, req: :ok),
+      begin unknown(:not_ok, unknown_kwarg: :not_ok) rescue ArgumentError; :ok end,
+    ]
+  end
+
+  tests
+}
+
+# test simple iseqs not eligible for inlining
+assert_equal '[:ok, :ok, :ok, :ok, :ok]', %q{
+  def identity(x) = x
+  def arg_splat(x, *args) = x
+  def kwarg_splat(x, **kwargs) = x
+  def block_arg(x, &blk) = x
+  def block_iseq(x) = x
+  def call_forwarding(...) = identity(...)
+
+  def tests
+    [
+      arg_splat(:ok),
+      kwarg_splat(:ok),
+      block_arg(:ok, &proc { :not_ok }),
+      block_iseq(:ok) { :not_ok },
+      call_forwarding(:ok),
+    ]
+  end
+
+  tests
+}
+
+# regression test for splat with &proc{} when the target has rest (Bug #21266)
+assert_equal '[]', %q{
+  def foo(args) = bar(*args, &proc { _1 })
+  def bar(_, _, _, _, *rest) = yield rest
+
+  GC.stress = true
+  foo([1,2,3,4])
+  foo([1,2,3,4])
+}
+
+# regression test for invalidating an empty block
+assert_equal '0', %q{
+  def foo = (* = 1).pred
+
+  foo # compile it
+
+  class Integer
+    def to_ary = [] # invalidate
+  end
+
+  foo # try again
+}
+
+# test integer left shift with constant rhs
+assert_equal [0x80000000000, 'a+', :ok].inspect, %q{
+  def shift(val) = val << 43
+
+  def tests
+    int = shift(1)
+    str = shift("a")
+
+    Integer.define_method(:<<) { |_| :ok }
+    redef = shift(1)
+
+    [int, str, redef]
+  end
+
+  tests
+}
+
+# test integer left shift fusion followed by opt_getconstant_path
+assert_equal '33', %q{
+  def test(a)
+    (a << 5) | (Object; a)
+  end
+
+  test(1)
+}
+
+# test String#stebyte with arguments that need conversion
+assert_equal "abc", %q{
+  str = +"a00"
+  def change_bytes(str, one, two)
+    str.setbyte(one, "b".ord)
+    str.setbyte(2, two)
+  end
+
+  to_int_1 = Object.new
+  to_int_99 = Object.new
+  def to_int_1.to_int = 1
+  def to_int_99.to_int = 99
+
+  change_bytes(str, to_int_1, to_int_99)
+  str
+}
+
+# test --yjit-verify-ctx for arrays with a singleton class
+assert_equal "ok", %q{
+  class Array
+    def foo
+      self.singleton_class.define_method(:first) { :ok }
+      first
+    end
+  end
+
+  def test = [].foo
+
+  test
+}
+
+assert_equal '["raised", "Module", "Object"]', %q{
+  def foo(obj)
+    obj.superclass.name
+  end
+
+  ret = []
+
+  begin
+    foo(Class.allocate)
+  rescue TypeError
+    ret << 'raised'
+  end
+
+  ret += [foo(Class), foo(Class.new)]
+}
+
+# test TrueClass#=== before and after redefining TrueClass#==
+assert_equal '[[true, false, false], [true, true, false], [true, :error, :error]]', %q{
+  def true_eqq(x)
+    true === x
+  rescue NoMethodError
+    :error
+  end
+
+  def test
+    [
+      # first one is always true because rb_equal does object comparison before calling #==
+      true_eqq(true),
+      # these will use TrueClass#==
+      true_eqq(false),
+      true_eqq(:truthy),
+    ]
+  end
+
+  results = [test]
+
+  class TrueClass
+    def ==(x)
+      !x
+    end
+  end
+
+  results << test
+
+  class TrueClass
+    undef_method :==
+  end
+
+  results << test
+}
+
+# test FalseClass#=== before and after redefining FalseClass#==
+assert_equal '[[true, false, false], [true, false, true], [true, :error, :error]]', %q{
+  def case_equal(x, y)
+    x === y
+  rescue NoMethodError
+    :error
+  end
+
+  def test
+    [
+      # first one is always true because rb_equal does object comparison before calling #==
+      case_equal(false, false),
+      # these will use #==
+      case_equal(false, true),
+      case_equal(false, nil),
+    ]
+  end
+
+  results = [test]
+
+  class FalseClass
+    def ==(x)
+      !x
+    end
+  end
+
+  results << test
+
+  class FalseClass
+    undef_method :==
+  end
+
+  results << test
+}
+
+# test NilClass#=== before and after redefining NilClass#==
+assert_equal '[[true, false, false], [true, false, true], [true, :error, :error]]', %q{
+  def case_equal(x, y)
+    x === y
+  rescue NoMethodError
+    :error
+  end
+
+  def test
+    [
+      # first one is always true because rb_equal does object comparison before calling #==
+      case_equal(nil, nil),
+      # these will use #==
+      case_equal(nil, true),
+      case_equal(nil, false),
+    ]
+  end
+
+  results = [test]
+
+  class NilClass
+    def ==(x)
+      !x
+    end
+  end
+
+  results << test
+
+  class NilClass
+    undef_method :==
+  end
+
+  results << test
+}
+
+# test struct accessors fire c_call events
+assert_equal '[[:c_call, :x=], [:c_call, :x]]', %q{
+  c = Struct.new(:x)
+  obj = c.new
+
+  events = []
+  TracePoint.new(:c_call) do
+    events << [_1.event, _1.method_id]
+  end.enable do
+    obj.x = 100
+    obj.x
+  end
+
+  events
+}
+
+# regression test for splatting empty array
+assert_equal '1', %q{
+  def callee(foo) = foo
+
+  def test_body(args) = callee(1, *args)
+
+  test_body([])
+  array = Array.new(100)
+  array.clear
+  test_body(array)
+}
+
+# regression test for splatting empty array to cfunc
+assert_normal_exit %q{
+  def test_body(args) = Array(1, *args)
+
+  test_body([])
+  0x100.times do
+    array = Array.new(100)
+    array.clear
+    test_body(array)
+  end
+}
+
+# compiling code shouldn't emit warnings as it may call into more Ruby code
+assert_equal 'ok', <<~'RUBY'
+  # [Bug #20522]
+  $VERBOSE = true
+  Warning[:performance] = true
+
+  module StrictWarnings
+    def warn(msg, **)
+      raise msg
+    end
+  end
+  Warning.singleton_class.prepend(StrictWarnings)
+
+  class A
+    def compiled_method(is_private)
+      @some_ivar = is_private
+    end
+  end
+
+  shape_max_variations = 8
+  if defined?(RubyVM::Shape::SHAPE_MAX_VARIATIONS) && RubyVM::Shape::SHAPE_MAX_VARIATIONS != shape_max_variations
+    raise "Expected SHAPE_MAX_VARIATIONS to be #{shape_max_variations}, got: #{RubyVM::Shape::SHAPE_MAX_VARIATIONS}"
+  end
+
+  100.times do |i|
+    klass = Class.new(A)
+    (shape_max_variations - 1).times do |j|
+      obj = klass.new
+      obj.instance_variable_set("@base_#{i}", 42)
+      obj.instance_variable_set("@ivar_#{j}", 42)
+    end
+    obj = klass.new
+    obj.instance_variable_set("@base_#{i}", 42)
+    begin
+      obj.compiled_method(true)
+    rescue
+      # expected
+    end
+  end
+
+  :ok
+RUBY
+
+assert_equal 'ok', <<~'RUBY'
+  class MyRelation
+    def callee(...)
+      :ok
+    end
+
+    def uncached(...)
+      callee(...)
+    end
+
+    def takes_block(&block)
+      # push blockhandler
+      uncached(&block) # CI1
+    end
+  end
+
+  relation = MyRelation.new
+  relation.takes_block { }
+RUBY
+
+assert_equal 'ok', <<~'RUBY'
+  def _exec_scope(...)
+    instance_exec(...)
+  end
+
+  def ok args, body
+    _exec_scope(*args, &body)
+  end
+
+  ok([], -> { "ok" })
+RUBY
+
+assert_equal 'ok', <<~'RUBY'
+  def _exec_scope(...)
+    instance_exec(...)
+  end
+
+  def ok args, body
+    _exec_scope(*args, &body)
+  end
+
+  ok(["ok"], ->(x) { x })
+RUBY
+
+assert_equal 'ok', <<~'RUBY'
+def baz(a, b)
+  a + b
+end
+
+def bar(...)
+  baz(...)
+end
+
+def foo(a, ...)
+  bar(a, ...)
+end
+
+def test
+  foo("o", "k")
+end
+
+test
+RUBY
+
+# opt_newarray_send pack/buffer
+assert_equal '[true, true]', <<~'RUBY'
+  def pack
+    v = 1.23
+    [v, v*2, v*3].pack("E*").unpack("E*") == [v, v*2, v*3]
+  end
+
+  def with_buffer
+    v = 4.56
+    b = +"x"
+    [v, v*2, v*3].pack("E*", buffer: b)
+    b[1..].unpack("E*") == [v, v*2, v*3]
+  end
+
+  [pack, with_buffer]
+RUBY
+
+# String#[] / String#slice
+assert_equal 'ok', <<~'RUBY'
+  def error(klass)
+    yield
+  rescue klass
+    true
+  end
+
+  def test
+    str = "こんにちは"
+    substr = "にち"
+    failures = []
+
+    # Use many small statements to keep context for each slice call smaller than MAX_CTX_TEMPS
+
+    str[1] == "ん" && str.slice(4) == "は" || failures << :index
+    str[5].nil? && str.slice(5).nil? || failures << :index_end
+
+    str[1, 2] == "んに" && str.slice(2, 1) == "に" || failures << :beg_len
+    str[5, 1] == "" && str.slice(5, 1) == "" || failures << :beg_len_end
+
+    str[1..2] == "んに" && str.slice(2..2) == "に" || failures << :range
+
+    str[/に./] == "にち" && str.slice(/に./) == "にち" || failures << :regexp
+
+    str[/に./, 0] == "にち" && str.slice(/に./, 0) == "にち" || failures << :regexp_cap0
+
+    str[/に(.)/, 1] == "ち" && str.slice(/に(.)/, 1) == "ち" || failures << :regexp_cap1
+
+    str[substr] == substr && str.slice(substr) == substr || failures << :substr
+
+    error(TypeError) { str[Object.new] } && error(TypeError) { str.slice(Object.new, 1) } || failures << :type_error
+    error(RangeError) { str[Float::INFINITY] } && error(RangeError) { str.slice(Float::INFINITY) } || failures << :range_error
+
+    return "ok" if failures.empty?
+    {failures: failures}
+  end
+
+  test
+RUBY
+
+# opt_duparray_send :include?
+assert_equal '[true, false]', <<~'RUBY'
+  def test(x)
+    [:a, :b].include?(x)
+  end
+
+  [
+    test(:b),
+    test(:c),
+  ]
+RUBY
+
+# opt_newarray_send :include?
+assert_equal '[true, false]', <<~'RUBY'
+  def test(x)
+    [Object.new, :a, :b].include?(x.to_sym)
+  end
+
+  [
+    test("b"),
+    test("c"),
+  ]
+RUBY
+
+# YARV: swap and opt_reverse
+assert_equal '["x", "Y", "c", "A", "t", "A", "b", "C", "d"]', <<~'RUBY'
+  class Swap
+    def initialize(s)
+      @a, @b, @c, @d = s.split("")
+    end
+
+    def swap
+      a, b = @a, @b
+      b = b.upcase
+      @a, @b = a, b
+    end
+
+    def reverse_odd
+      a, b, c = @a, @b, @c
+      b = b.upcase
+      @a, @b, @c = a, b, c
+    end
+
+    def reverse_even
+      a, b, c, d = @a, @b, @c, @d
+      a = a.upcase
+      c = c.upcase
+      @a, @b, @c, @d = a, b, c, d
+    end
+  end
+
+  Swap.new("xy").swap + Swap.new("cat").reverse_odd + Swap.new("abcd").reverse_even
+RUBY
+
+assert_normal_exit %{
+  class Bug20997
+    def foo(&) = self.class.name(&)
+
+    new.foo
+  end
+}
+
+# This used to trigger a "try to mark T_NONE"
+# due to an uninitialized local in foo.
+assert_normal_exit %{
+  def foo(...)
+    _local_that_should_nil_on_call = GC.start
+  end
+
+  def test_bug21021
+    puts [], [], [], [], [], []
+    foo []
+  end
+
+  GC.stress = true
+  test_bug21021
+}
+
+assert_equal 'nil', %{
+  def foo(...)
+    _a = _b = _c = binding.local_variable_get(:_c)
+
+    _c
+  end
+
+  # [Bug #21021]
+  def test_local_fill_in_forwardable
+    puts [], [], [], [], []
+    foo []
+  end
+
+  test_local_fill_in_forwardable.inspect
+}
+
+# Test defined?(yield) and block_given? in non-method context.
+# It's good that the body of this runs at true top level and isn't wrapped in a block.
+assert_equal 'false', %{
+  RESULT = []
+  RESULT << defined?(yield)
+  RESULT << block_given?
+
+  1.times do
+    RESULT << defined?(yield)
+    RESULT << block_given?
+  end
+
+  module ModuleContext
+    1.times do
+      RESULT << defined?(yield)
+      RESULT << block_given?
+    end
+  end
+
+  class << self
+    RESULT << defined?(yield)
+    RESULT << block_given?
+  end
+
+  RESULT.any?
+}
+
+# throw and String#dup with GC stress
+assert_equal 'foo', %{
+  GC.stress = true
+
+  def foo
+    1.times { return "foo".dup }
+  end
+
+  10.times.map { foo.dup }.last
+}
+
+# regression test for [Bug #21772]
+# local variable type tracking desync
+assert_normal_exit %q{
+  def some_method = 0
+
+  def test_body(key)
+    some_method
+    key = key.to_s # setting of local relevant
+
+    key == "symbol"
+  end
+
+  def jit_caller = test_body("session_id")
+
+  jit_caller # first iteration, non-escaped environment
+  alias some_method binding # induce environment escape
+  test_body(:symbol)
+}
+
+# regression test for missing check in identity method inlining
+assert_normal_exit %q{
+  # Use dead code (if false) to create a local
+  # without initialization instructions.
+  def foo(a)
+    if false
+      x = nil
+    end
+    x
+  end
+  def test = foo(1)
+  test
+  test
+}
diff --git a/bootstraptest/test_yjit_rust_port.rb b/bootstraptest/test_yjit_rust_port.rb
index e399e0e49e..2dbcebc03a 100644
--- a/bootstraptest/test_yjit_rust_port.rb
+++ b/bootstraptest/test_yjit_rust_port.rb
@@ -374,7 +374,7 @@ assert_equal 'ok', %q{
   r = Ractor.new do
     'ok'
   end
-  r.take
+  r.value
 }
 
 # Passed arguments to Ractor.new will be a block parameter
@@ -384,7 +384,7 @@ assert_equal 'ok', %q{
   r = Ractor.new 'ok' do |msg|
     msg
   end
-  r.take
+  r.value
 }
 
 # Pass multiple arguments to Ractor.new
@@ -393,7 +393,7 @@ assert_equal 'ok', %q{
   r =  Ractor.new 'ping', 'pong' do |msg, msg2|
     [msg, msg2]
   end
-  'ok' if r.take == ['ping', 'pong']
+  'ok' if r.value == ['ping', 'pong']
 }
 
 # Ractor#send passes an object with copy to a Ractor
@@ -403,7 +403,7 @@ assert_equal 'ok', %q{
     msg = Ractor.receive
   end
   r.send 'ok'
-  r.take
+  r.value
 }
 
 assert_equal '[1, 2, 3]', %q{
diff --git a/box.c b/box.c
new file mode 100644
index 0000000000..830172cdd5
--- /dev/null
+++ b/box.c
@@ -0,0 +1,1220 @@
+/* indent-tabs-mode: nil */
+
+#include "eval_intern.h"
+#include "internal.h"
+#include "internal/box.h"
+#include "internal/class.h"
+#include "internal/eval.h"
+#include "internal/error.h"
+#include "internal/file.h"
+#include "internal/gc.h"
+#include "internal/hash.h"
+#include "internal/io.h"
+#include "internal/load.h"
+#include "internal/st.h"
+#include "internal/variable.h"
+#include "iseq.h"
+#include "ruby/internal/globals.h"
+#include "ruby/util.h"
+#include "vm_core.h"
+#include "darray.h"
+
+#include <stdio.h>
+
+#ifdef HAVE_SYS_SENDFILE_H
+# include <sys/sendfile.h>
+#endif
+#ifdef HAVE_COPYFILE_H
+#include <copyfile.h>
+#endif
+
+VALUE rb_cBox = 0;
+VALUE rb_cBoxEntry = 0;
+VALUE rb_mBoxLoader = 0;
+
+static rb_box_t root_box[1]; /* Initialize in initialize_root_box() */
+static rb_box_t *main_box;
+static char *tmp_dir;
+static bool tmp_dir_has_dirsep;
+
+#define BOX_TMP_PREFIX "_ruby_box_"
+
+#ifndef MAXPATHLEN
+# define MAXPATHLEN 1024
+#endif
+
+#if defined(_WIN32)
+# define DIRSEP "\\"
+#else
+# define DIRSEP "/"
+#endif
+
+bool ruby_box_enabled = false; // extern
+bool ruby_box_init_done = false; // extern
+bool ruby_box_crashed = false; // extern, changed only in vm.c
+
+VALUE rb_resolve_feature_path(VALUE klass, VALUE fname);
+static VALUE rb_box_inspect(VALUE obj);
+static void cleanup_all_local_extensions(VALUE libmap);
+
+void
+rb_box_init_done(void)
+{
+    ruby_box_init_done = true;
+}
+
+const rb_box_t *
+rb_root_box(void)
+{
+    return root_box;
+}
+
+const rb_box_t *
+rb_main_box(void)
+{
+    return main_box;
+}
+
+const rb_box_t *
+rb_current_box(void)
+{
+    /*
+     * If RUBY_BOX is not set, the root box is the only available one.
+     *
+     * Until the main_box is not initialized, the root box is
+     * the only valid box.
+     * This early return is to avoid accessing EC before its setup.
+     */
+    if (!main_box)
+        return root_box;
+
+    return rb_vm_current_box(GET_EC());
+}
+
+const rb_box_t *
+rb_loading_box(void)
+{
+    if (!main_box)
+        return root_box;
+
+    return rb_vm_loading_box(GET_EC());
+}
+
+const rb_box_t *
+rb_current_box_in_crash_report(void)
+{
+    if (ruby_box_crashed)
+        return NULL;
+    return rb_current_box();
+}
+
+static long box_id_counter = 0;
+
+static long
+box_generate_id(void)
+{
+    long id;
+    RB_VM_LOCKING() {
+        id = ++box_id_counter;
+    }
+    return id;
+}
+
+static VALUE
+box_main_to_s(VALUE obj)
+{
+    return rb_str_new2("main");
+}
+
+static void
+box_entry_initialize(rb_box_t *box)
+{
+    const rb_box_t *root = rb_root_box();
+
+    // These will be updated immediately
+    box->box_object = 0;
+    box->box_id = 0;
+
+    box->top_self = rb_obj_alloc(rb_cObject);
+    rb_define_singleton_method(box->top_self, "to_s", box_main_to_s, 0);
+    rb_define_alias(rb_singleton_class(box->top_self), "inspect", "to_s");
+    box->load_path = rb_ary_dup(root->load_path);
+    box->expanded_load_path = rb_ary_dup(root->expanded_load_path);
+    box->load_path_snapshot = rb_ary_new();
+    box->load_path_check_cache = 0;
+    box->loaded_features = rb_ary_dup(root->loaded_features);
+    box->loaded_features_snapshot = rb_ary_new();
+    box->loaded_features_index = st_init_numtable();
+    box->loaded_features_realpaths = rb_hash_dup(root->loaded_features_realpaths);
+    box->loaded_features_realpath_map = rb_hash_dup(root->loaded_features_realpath_map);
+    box->loading_table = st_init_strtable();
+    box->ruby_dln_libmap = rb_hash_new_with_size(0);
+    box->gvar_tbl = rb_hash_new_with_size(0);
+    box->classext_cow_classes = st_init_numtable();
+
+    box->is_user = true;
+    box->is_optional = true;
+}
+
+void
+rb_box_gc_update_references(void *ptr)
+{
+    rb_box_t *box = (rb_box_t *)ptr;
+    if (!box) return;
+
+    if (box->box_object)
+        box->box_object = rb_gc_location(box->box_object);
+    if (box->top_self)
+        box->top_self = rb_gc_location(box->top_self);
+    box->load_path = rb_gc_location(box->load_path);
+    box->expanded_load_path = rb_gc_location(box->expanded_load_path);
+    box->load_path_snapshot = rb_gc_location(box->load_path_snapshot);
+    if (box->load_path_check_cache) {
+        box->load_path_check_cache = rb_gc_location(box->load_path_check_cache);
+    }
+    box->loaded_features = rb_gc_location(box->loaded_features);
+    box->loaded_features_snapshot = rb_gc_location(box->loaded_features_snapshot);
+    box->loaded_features_realpaths = rb_gc_location(box->loaded_features_realpaths);
+    box->loaded_features_realpath_map = rb_gc_location(box->loaded_features_realpath_map);
+    box->ruby_dln_libmap = rb_gc_location(box->ruby_dln_libmap);
+    box->gvar_tbl = rb_gc_location(box->gvar_tbl);
+}
+
+void
+rb_box_entry_mark(void *ptr)
+{
+    const rb_box_t *box = (rb_box_t *)ptr;
+    if (!box) return;
+
+    rb_gc_mark(box->box_object);
+    rb_gc_mark(box->top_self);
+    rb_gc_mark(box->load_path);
+    rb_gc_mark(box->expanded_load_path);
+    rb_gc_mark(box->load_path_snapshot);
+    rb_gc_mark(box->load_path_check_cache);
+    rb_gc_mark(box->loaded_features);
+    rb_gc_mark(box->loaded_features_snapshot);
+    rb_gc_mark(box->loaded_features_realpaths);
+    rb_gc_mark(box->loaded_features_realpath_map);
+    if (box->loading_table) {
+        rb_mark_tbl(box->loading_table);
+    }
+    rb_gc_mark(box->ruby_dln_libmap);
+    rb_gc_mark(box->gvar_tbl);
+    if (box->classext_cow_classes) {
+        rb_mark_tbl(box->classext_cow_classes);
+    }
+}
+
+static int
+free_loading_table_entry(st_data_t key, st_data_t value, st_data_t arg)
+{
+    xfree((char *)key);
+    return ST_DELETE;
+}
+
+static int
+free_loaded_feature_index_i(st_data_t key, st_data_t value, st_data_t arg)
+{
+    if (!FIXNUM_P(value)) {
+        rb_darray_free((void *)value);
+    }
+    return ST_CONTINUE;
+}
+
+static void
+box_root_free(void *ptr)
+{
+    rb_box_t *box = (rb_box_t *)ptr;
+    if (box->loading_table) {
+        st_foreach(box->loading_table, free_loading_table_entry, 0);
+        st_free_table(box->loading_table);
+        box->loading_table = 0;
+    }
+
+    if (box->loaded_features_index) {
+        st_foreach(box->loaded_features_index, free_loaded_feature_index_i, 0);
+        st_free_table(box->loaded_features_index);
+    }
+}
+
+static int
+free_classext_for_box(st_data_t _key, st_data_t obj_value, st_data_t box_arg)
+{
+    rb_classext_t *ext;
+    VALUE obj = (VALUE)obj_value;
+    const rb_box_t *box = (const rb_box_t *)box_arg;
+
+    if (RB_TYPE_P(obj, T_CLASS) || RB_TYPE_P(obj, T_MODULE)) {
+        ext = rb_class_unlink_classext(obj, box);
+        rb_class_classext_free(obj, ext, false);
+    }
+    else if (RB_TYPE_P(obj, T_ICLASS)) {
+        ext = rb_class_unlink_classext(obj, box);
+        rb_iclass_classext_free(obj, ext, false);
+    }
+    else {
+        rb_bug("Invalid type of object in classext_cow_classes: %s", rb_type_str(BUILTIN_TYPE(obj)));
+    }
+    return ST_CONTINUE;
+}
+
+static void
+box_entry_free(void *ptr)
+{
+    const rb_box_t *box = (const rb_box_t *)ptr;
+
+    if (box->classext_cow_classes) {
+        st_foreach(box->classext_cow_classes, free_classext_for_box, (st_data_t)box);
+    }
+
+    cleanup_all_local_extensions(box->ruby_dln_libmap);
+
+    box_root_free(ptr);
+    xfree(ptr);
+}
+
+static size_t
+box_entry_memsize(const void *ptr)
+{
+    size_t size = sizeof(rb_box_t);
+    const rb_box_t *box = (const rb_box_t *)ptr;
+    if (box->loaded_features_index) {
+        size += rb_st_memsize(box->loaded_features_index);
+    }
+    if (box->loading_table) {
+        size += rb_st_memsize(box->loading_table);
+    }
+    return size;
+}
+
+static const rb_data_type_t rb_box_data_type = {
+    "Ruby::Box::Entry",
+    {
+        rb_box_entry_mark,
+        box_entry_free,
+        box_entry_memsize,
+        rb_box_gc_update_references,
+    },
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY // TODO: enable RUBY_TYPED_WB_PROTECTED when inserting write barriers
+};
+
+static const rb_data_type_t rb_root_box_data_type = {
+    "Ruby::Box::Root",
+    {
+        rb_box_entry_mark,
+        box_root_free,
+        box_entry_memsize,
+        rb_box_gc_update_references,
+    },
+    &rb_box_data_type, 0, RUBY_TYPED_FREE_IMMEDIATELY // TODO: enable RUBY_TYPED_WB_PROTECTED when inserting write barriers
+};
+
+VALUE
+rb_box_entry_alloc(VALUE klass)
+{
+    rb_box_t *entry;
+    VALUE obj = TypedData_Make_Struct(klass, rb_box_t, &rb_box_data_type, entry);
+    box_entry_initialize(entry);
+    return obj;
+}
+
+static rb_box_t *
+get_box_struct_internal(VALUE entry)
+{
+    rb_box_t *sval;
+    TypedData_Get_Struct(entry, rb_box_t, &rb_box_data_type, sval);
+    return sval;
+}
+
+rb_box_t *
+rb_get_box_t(VALUE box)
+{
+    VALUE entry;
+    ID id_box_entry;
+
+    VM_ASSERT(box);
+
+    if (NIL_P(box))
+        return root_box;
+
+    VM_ASSERT(BOX_OBJ_P(box));
+
+    CONST_ID(id_box_entry, "__box_entry__");
+    entry = rb_attr_get(box, id_box_entry);
+    return get_box_struct_internal(entry);
+}
+
+VALUE
+rb_get_box_object(rb_box_t *box)
+{
+    VM_ASSERT(box && box->box_object);
+    return box->box_object;
+}
+
+/*
+ *  call-seq:
+ *    Ruby::Box.new -> new_box
+ *
+ *  Returns a new Ruby::Box object.
+ */
+static VALUE
+box_initialize(VALUE box_value)
+{
+    rb_box_t *box;
+    rb_classext_t *object_classext;
+    VALUE entry;
+    ID id_box_entry;
+    CONST_ID(id_box_entry, "__box_entry__");
+
+    if (!rb_box_available()) {
+        rb_raise(rb_eRuntimeError, "Ruby Box is disabled. Set RUBY_BOX=1 environment variable to use Ruby::Box.");
+    }
+
+    entry = rb_class_new_instance_pass_kw(0, NULL, rb_cBoxEntry);
+    box = get_box_struct_internal(entry);
+
+    box->box_object = box_value;
+    box->box_id = box_generate_id();
+    rb_define_singleton_method(box->load_path, "resolve_feature_path", rb_resolve_feature_path, 1);
+
+    // Set the Ruby::Box object unique/consistent from any boxes to have just single
+    // constant table from any view of every (including main) box.
+    // If a code in the box adds a constant, the constant will be visible even from root/main.
+    RCLASS_SET_PRIME_CLASSEXT_WRITABLE(box_value, true);
+
+    // Get a clean constant table of Object even by writable one
+    // because ns was just created, so it has not touched any constants yet.
+    object_classext = RCLASS_EXT_WRITABLE_IN_BOX(rb_cObject, box);
+    RCLASS_SET_CONST_TBL(box_value, RCLASSEXT_CONST_TBL(object_classext), true);
+
+    rb_ivar_set(box_value, id_box_entry, entry);
+
+    return box_value;
+}
+
+/*
+ *  call-seq:
+ *    Ruby::Box.enabled? -> true or false
+ *
+ *  Returns +true+ if Ruby::Box is enabled.
+ */
+static VALUE
+rb_box_s_getenabled(VALUE recv)
+{
+    return RBOOL(rb_box_available());
+}
+
+/*
+ *  call-seq:
+ *    Ruby::Box.current -> box, nil or false
+ *
+ *  Returns the current box.
+ *  Returns +nil+ if Ruby Box is not enabled.
+ */
+static VALUE
+rb_box_s_current(VALUE recv)
+{
+    const rb_box_t *box;
+
+    if (!rb_box_available())
+        return Qnil;
+
+    box = rb_vm_current_box(GET_EC());
+    VM_ASSERT(box && box->box_object);
+    return box->box_object;
+}
+
+/*
+ *  call-seq:
+ *    load_path -> array
+ *
+ *  Returns box local load path.
+ */
+static VALUE
+rb_box_load_path(VALUE box)
+{
+    VM_ASSERT(BOX_OBJ_P(box));
+    return rb_get_box_t(box)->load_path;
+}
+
+#ifdef _WIN32
+UINT rb_w32_system_tmpdir(WCHAR *path, UINT len);
+#endif
+
+/* Copied from mjit.c Ruby 3.0.3 */
+static char *
+system_default_tmpdir(void)
+{
+    // c.f. ext/etc/etc.c:etc_systmpdir()
+#ifdef _WIN32
+    WCHAR tmppath[_MAX_PATH];
+    UINT len = rb_w32_system_tmpdir(tmppath, numberof(tmppath));
+    if (len) {
+        int blen = WideCharToMultiByte(CP_UTF8, 0, tmppath, len, NULL, 0, NULL, NULL);
+        char *tmpdir = xmalloc(blen + 1);
+        WideCharToMultiByte(CP_UTF8, 0, tmppath, len, tmpdir, blen, NULL, NULL);
+        tmpdir[blen] = '\0';
+        return tmpdir;
+    }
+#elif defined _CS_DARWIN_USER_TEMP_DIR
+    char path[MAXPATHLEN];
+    size_t len = confstr(_CS_DARWIN_USER_TEMP_DIR, path, sizeof(path));
+    if (len > 0) {
+        char *tmpdir = xmalloc(len);
+        if (len > sizeof(path)) {
+            confstr(_CS_DARWIN_USER_TEMP_DIR, tmpdir, len);
+        }
+        else {
+            memcpy(tmpdir, path, len);
+        }
+        return tmpdir;
+    }
+#endif
+    return 0;
+}
+
+static int
+check_tmpdir(const char *dir)
+{
+    struct stat st;
+
+    if (!dir) return FALSE;
+    if (stat(dir, &st)) return FALSE;
+#ifndef S_ISDIR
+#   define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
+#endif
+    if (!S_ISDIR(st.st_mode)) return FALSE;
+#ifndef _WIN32
+# ifndef S_IWOTH
+#   define S_IWOTH 002
+# endif
+    if (st.st_mode & S_IWOTH) {
+# ifdef S_ISVTX
+        if (!(st.st_mode & S_ISVTX)) return FALSE;
+# else
+        return FALSE;
+# endif
+    }
+    if (access(dir, W_OK)) return FALSE;
+#endif
+    return TRUE;
+}
+
+static char *
+system_tmpdir(void)
+{
+    char *tmpdir;
+# define RETURN_ENV(name) \
+    if (check_tmpdir(tmpdir = getenv(name))) return ruby_strdup(tmpdir)
+    RETURN_ENV("TMPDIR");
+    RETURN_ENV("TMP");
+    tmpdir = system_default_tmpdir();
+    if (check_tmpdir(tmpdir)) return tmpdir;
+    return ruby_strdup("/tmp");
+# undef RETURN_ENV
+}
+
+/* end of copy */
+
+static int
+sprint_ext_filename(char *str, size_t size, long box_id, const char *prefix, const char *basename)
+{
+    if (tmp_dir_has_dirsep) {
+        return snprintf(str, size, "%s%sp%"PRI_PIDT_PREFIX"u_%ld_%s", tmp_dir, prefix, getpid(), box_id, basename);
+    }
+    return snprintf(str, size, "%s%s%sp%"PRI_PIDT_PREFIX"u_%ld_%s", tmp_dir, DIRSEP, prefix, getpid(), box_id, basename);
+}
+
+enum copy_error_type {
+    COPY_ERROR_NONE,
+    COPY_ERROR_SRC_OPEN,
+    COPY_ERROR_DST_OPEN,
+    COPY_ERROR_SRC_READ,
+    COPY_ERROR_DST_WRITE,
+    COPY_ERROR_SRC_STAT,
+    COPY_ERROR_DST_CHMOD,
+    COPY_ERROR_SYSERR
+};
+
+static const char *
+copy_ext_file_error(char *message, size_t size, int copy_retvalue)
+{
+#ifdef _WIN32
+    int error = GetLastError();
+    char *p = message;
+    size_t len = snprintf(message, size, "%d: ", error);
+
+#define format_message(sublang) FormatMessage(\
+        FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,	\
+        NULL, error, MAKELANGID(LANG_NEUTRAL, (sublang)),		\
+        message + len, size - len, NULL)
+    if (format_message(SUBLANG_ENGLISH_US) == 0)
+        format_message(SUBLANG_DEFAULT);
+    for (p = message + len; *p; p++) {
+        if (*p == '\n' || *p == '\r')
+            *p = ' ';
+    }
+#else
+    switch (copy_retvalue) {
+      case COPY_ERROR_SRC_OPEN:
+        strlcpy(message, "can't open the extension path", size);
+        break;
+      case COPY_ERROR_DST_OPEN:
+        strlcpy(message, "can't open the file to write", size);
+        break;
+      case COPY_ERROR_SRC_READ:
+        strlcpy(message, "failed to read the extension path", size);
+        break;
+      case COPY_ERROR_DST_WRITE:
+        strlcpy(message, "failed to write the extension path", size);
+        break;
+      case COPY_ERROR_SRC_STAT:
+        strlcpy(message, "failed to stat the extension path to copy permissions", size);
+        break;
+      case COPY_ERROR_DST_CHMOD:
+        strlcpy(message, "failed to set permissions to the copied extension path", size);
+        break;
+      case COPY_ERROR_SYSERR:
+        strlcpy(message, strerror(errno), size);
+        break;
+      case COPY_ERROR_NONE: /* shouldn't be called */
+      default:
+        rb_bug("unknown return value of copy_ext_file: %d", copy_retvalue);
+    }
+#endif
+    return message;
+}
+
+#ifndef _WIN32
+static enum copy_error_type
+copy_stream(int src_fd, int dst_fd)
+{
+    char buffer[1024];
+    ssize_t rsize;
+
+    while ((rsize = read(src_fd, buffer, sizeof(buffer))) != 0) {
+        if (rsize < 0) return COPY_ERROR_SRC_READ;
+        for (size_t written = 0; written < (size_t)rsize;) {
+            ssize_t wsize = write(dst_fd, buffer+written, rsize-written);
+            if (wsize < 0) return COPY_ERROR_DST_WRITE;
+            written += (size_t)wsize;
+        }
+    }
+    return COPY_ERROR_NONE;
+}
+#endif
+
+static enum copy_error_type
+copy_ext_file(const char *src_path, const char *dst_path)
+{
+#if defined(_WIN32)
+    WCHAR *w_src = rb_w32_mbstr_to_wstr(CP_UTF8, src_path, -1, NULL);
+    WCHAR *w_dst = rb_w32_mbstr_to_wstr(CP_UTF8, dst_path, -1, NULL);
+    if (!w_src || !w_dst) {
+        free(w_src);
+        free(w_dst);
+        rb_memerror();
+    }
+
+    enum copy_error_type rvalue = CopyFileW(w_src, w_dst, TRUE) ?
+        COPY_ERROR_NONE : COPY_ERROR_SYSERR;
+    free(w_src);
+    free(w_dst);
+    return rvalue;
+#else
+# ifdef O_BINARY
+    const int bin = O_BINARY;
+# else
+    const int bin = 0;
+# endif
+# ifdef O_CLOEXEC
+    const int cloexec = O_CLOEXEC;
+# else
+    const int cloexec = 0;
+# endif
+    const int src_fd = open(src_path, O_RDONLY|cloexec|bin);
+    if (src_fd < 0) return COPY_ERROR_SRC_OPEN;
+    if (!cloexec) rb_maygvl_fd_fix_cloexec(src_fd);
+
+    struct stat src_st;
+    if (fstat(src_fd, &src_st)) {
+        close(src_fd);
+        return COPY_ERROR_SRC_STAT;
+    }
+
+    const int dst_fd = open(dst_path, O_WRONLY|O_CREAT|O_EXCL|cloexec|bin, S_IRWXU);
+    if (dst_fd < 0) {
+        close(src_fd);
+        return COPY_ERROR_DST_OPEN;
+    }
+    if (!cloexec) rb_maygvl_fd_fix_cloexec(dst_fd);
+
+    enum copy_error_type ret = COPY_ERROR_NONE;
+
+    if (fchmod(dst_fd, src_st.st_mode & 0777)) {
+        ret = COPY_ERROR_DST_CHMOD;
+        goto done;
+    }
+
+    const size_t count_max = (SIZE_MAX >> 1) + 1;
+    (void)count_max;
+
+# ifdef HAVE_COPY_FILE_RANGE
+    for (;;) {
+        ssize_t written = copy_file_range(src_fd, NULL, dst_fd, NULL, count_max, 0);
+        if (written == 0) goto done;
+        if (written < 0) break;
+    }
+# endif
+# ifdef HAVE_FCOPYFILE
+    if (fcopyfile(src_fd, dst_fd, NULL, COPYFILE_DATA) == 0) {
+        goto done;
+    }
+# endif
+# ifdef USE_SENDFILE
+    for (;;) {
+        ssize_t written = sendfile(src_fd, dst_fd, NULL count_max);
+        if (written == 0) goto done;
+        if (written < 0) break;
+    }
+# endif
+    ret = copy_stream(src_fd, dst_fd);
+
+  done:
+    close(src_fd);
+    if (dst_fd >= 0) close(dst_fd);
+    if (ret != COPY_ERROR_NONE) unlink(dst_path);
+    return ret;
+#endif
+}
+
+#if defined __CYGWIN__ || defined DOSISH
+#define isdirsep(x) ((x) == '/' || (x) == '\\')
+#else
+#define isdirsep(x) ((x) == '/')
+#endif
+
+#define IS_SOEXT(e) (strcmp((e), ".so") == 0 || strcmp((e), ".o") == 0)
+#define IS_DLEXT(e) (strcmp((e), DLEXT) == 0)
+
+static void
+fname_without_suffix(const char *fname, char *rvalue, size_t rsize)
+{
+    size_t len = strlen(fname);
+    const char *pos;
+    for (pos = fname + len; pos > fname; pos--) {
+        if (IS_SOEXT(pos) || IS_DLEXT(pos)) {
+            len = pos - fname;
+            break;
+        }
+        if (fname + len - pos > DLEXT_MAXLEN) break;
+    }
+    if (len > rsize - 1) len = rsize - 1;
+    memcpy(rvalue, fname, len);
+    rvalue[len] = '\0';
+}
+
+static void
+escaped_basename(const char *path, const char *fname, char *rvalue, size_t rsize)
+{
+    char *pos;
+    const char *leaf = path, *found;
+    // `leaf + 1` looks uncomfortable (when leaf == path), but fname must not be the top-dir itself
+    while ((found = strstr(leaf + 1, fname)) != NULL) {
+        leaf = found; // find the last occurrence for the path like /etc/my-crazy-lib-dir/etc.so
+    }
+    strlcpy(rvalue, leaf, rsize);
+    for (pos = rvalue; *pos; pos++) {
+        if (isdirsep(*pos)) {
+            *pos = '+';
+        }
+    }
+}
+
+static void
+box_ext_cleanup_mark(void *p)
+{
+    rb_gc_mark((VALUE)p);
+}
+
+static void
+box_ext_cleanup_free(void *p)
+{
+    VALUE path = (VALUE)p;
+    unlink(RSTRING_PTR(path));
+}
+
+static const rb_data_type_t box_ext_cleanup_type = {
+    "box_ext_cleanup",
+    {box_ext_cleanup_mark, box_ext_cleanup_free},
+    .flags = RUBY_TYPED_FREE_IMMEDIATELY,
+};
+
+void
+rb_box_cleanup_local_extension(VALUE cleanup)
+{
+    void *p = DATA_PTR(cleanup);
+    DATA_PTR(cleanup) = NULL;
+#ifndef _WIN32
+    if (p) box_ext_cleanup_free(p);
+#endif
+    (void)p;
+}
+
+static int
+cleanup_local_extension_i(VALUE key, VALUE value, VALUE arg)
+{
+#if defined(_WIN32)
+    HMODULE h = (HMODULE)NUM2PTR(value);
+    WCHAR module_path[MAXPATHLEN];
+    DWORD len = GetModuleFileNameW(h, module_path, numberof(module_path));
+
+    FreeLibrary(h);
+    if (len > 0 && len < numberof(module_path)) DeleteFileW(module_path);
+#endif
+    return ST_DELETE;
+}
+
+static void
+cleanup_all_local_extensions(VALUE libmap)
+{
+    rb_hash_foreach(libmap, cleanup_local_extension_i, 0);
+}
+
+VALUE
+rb_box_local_extension(VALUE box_value, VALUE fname, VALUE path, VALUE *cleanup)
+{
+    char ext_path[MAXPATHLEN], fname2[MAXPATHLEN], basename[MAXPATHLEN];
+    int wrote;
+    const char *src_path = RSTRING_PTR(path), *fname_ptr = RSTRING_PTR(fname);
+    rb_box_t *box = rb_get_box_t(box_value);
+
+    fname_without_suffix(fname_ptr, fname2, sizeof(fname2));
+    escaped_basename(src_path, fname2, basename, sizeof(basename));
+
+    wrote = sprint_ext_filename(ext_path, sizeof(ext_path), box->box_id, BOX_TMP_PREFIX, basename);
+    if (wrote >= (int)sizeof(ext_path)) {
+        rb_bug("Extension file path in the box was too long");
+    }
+    VALUE new_path = rb_str_new_cstr(ext_path);
+    *cleanup = TypedData_Wrap_Struct(0, &box_ext_cleanup_type, NULL);
+    enum copy_error_type copy_error = copy_ext_file(src_path, ext_path);
+    if (copy_error) {
+        char message[1024];
+        copy_ext_file_error(message, sizeof(message), copy_error);
+        rb_raise(rb_eLoadError, "can't prepare the extension file for Ruby Box (%s from %"PRIsVALUE"): %s", ext_path, path, message);
+    }
+    DATA_PTR(*cleanup) = (void *)new_path;
+    return new_path;
+}
+
+static VALUE
+rb_box_load(int argc, VALUE *argv, VALUE box)
+{
+    VALUE fname, wrap;
+    rb_scan_args(argc, argv, "11", &fname, &wrap);
+
+    rb_vm_frame_flag_set_box_require(GET_EC());
+
+    VALUE args = rb_ary_new_from_args(2, fname, wrap);
+    return rb_load_entrypoint(args);
+}
+
+static VALUE
+rb_box_require(VALUE box, VALUE fname)
+{
+    rb_vm_frame_flag_set_box_require(GET_EC());
+
+    return rb_require_string(fname);
+}
+
+static VALUE
+rb_box_require_relative(VALUE box, VALUE fname)
+{
+    rb_vm_frame_flag_set_box_require(GET_EC());
+
+    return rb_require_relative_entrypoint(fname);
+}
+
+static void
+initialize_root_box(void)
+{
+    rb_vm_t *vm = GET_VM();
+    rb_box_t *root = (rb_box_t *)rb_root_box();
+
+    root->load_path = rb_ary_new();
+    root->expanded_load_path = rb_ary_hidden_new(0);
+    root->load_path_snapshot = rb_ary_hidden_new(0);
+    root->load_path_check_cache = 0;
+    rb_define_singleton_method(root->load_path, "resolve_feature_path", rb_resolve_feature_path, 1);
+
+    root->loaded_features = rb_ary_new();
+    root->loaded_features_snapshot = rb_ary_hidden_new(0);
+    root->loaded_features_index = st_init_numtable();
+    root->loaded_features_realpaths = rb_hash_new();
+    rb_obj_hide(root->loaded_features_realpaths);
+    root->loaded_features_realpath_map = rb_hash_new();
+    rb_obj_hide(root->loaded_features_realpath_map);
+
+    root->ruby_dln_libmap = rb_hash_new_with_size(0);
+    root->gvar_tbl = rb_hash_new_with_size(0);
+    root->classext_cow_classes = NULL; // classext CoW never happen on the root box
+
+    vm->root_box = root;
+
+    if (rb_box_available()) {
+        VALUE root_box, entry;
+        ID id_box_entry;
+        CONST_ID(id_box_entry, "__box_entry__");
+
+        root_box = rb_obj_alloc(rb_cBox);
+        RCLASS_SET_PRIME_CLASSEXT_WRITABLE(root_box, true);
+        RCLASS_SET_CONST_TBL(root_box, RCLASSEXT_CONST_TBL(RCLASS_EXT_PRIME(rb_cObject)), true);
+
+        root->box_id = box_generate_id();
+        root->box_object = root_box;
+
+        entry = TypedData_Wrap_Struct(rb_cBoxEntry, &rb_root_box_data_type, root);
+        rb_ivar_set(root_box, id_box_entry, entry);
+    }
+    else {
+        root->box_id = 1;
+        root->box_object = Qnil;
+    }
+}
+
+static VALUE
+rb_box_eval(VALUE box_value, VALUE str)
+{
+    const rb_iseq_t *iseq;
+    const rb_box_t *box;
+
+    StringValue(str);
+
+    iseq = rb_iseq_compile_iseq(str, rb_str_new_cstr("eval"));
+    VM_ASSERT(iseq);
+
+    box = (const rb_box_t *)rb_get_box_t(box_value);
+
+    return rb_iseq_eval(iseq, box);
+}
+
+static int box_experimental_warned = 0;
+
+RUBY_EXTERN const char ruby_api_version_name[];
+
+void
+rb_initialize_main_box(void)
+{
+    rb_box_t *box;
+    VALUE main_box_value;
+    rb_vm_t *vm = GET_VM();
+
+    VM_ASSERT(rb_box_available());
+
+    if (!box_experimental_warned) {
+        rb_category_warn(RB_WARN_CATEGORY_EXPERIMENTAL,
+                         "Ruby::Box is experimental, and the behavior may change in the future!\n"
+                         "See https://docs.ruby-lang.org/en/%s/Ruby/Box.html for known issues, etc.",
+                         ruby_api_version_name);
+        box_experimental_warned = 1;
+    }
+
+    main_box_value = rb_class_new_instance(0, NULL, rb_cBox);
+    VM_ASSERT(BOX_OBJ_P(main_box_value));
+    box = rb_get_box_t(main_box_value);
+    box->box_object = main_box_value;
+    box->is_user = true;
+    box->is_optional = false;
+
+    rb_const_set(rb_cBox, rb_intern("MAIN"), main_box_value);
+
+    vm->main_box = main_box = box;
+
+    // create the writable classext of ::Object explicitly to finalize the set of visible top-level constants
+    RCLASS_EXT_WRITABLE_IN_BOX(rb_cObject, box);
+}
+
+static VALUE
+rb_box_inspect(VALUE obj)
+{
+    rb_box_t *box;
+    VALUE r;
+    if (obj == Qfalse) {
+        r = rb_str_new_cstr("#<Ruby::Box:root>");
+        return r;
+    }
+    box = rb_get_box_t(obj);
+    r = rb_str_new_cstr("#<Ruby::Box:");
+    rb_str_concat(r, rb_funcall(LONG2NUM(box->box_id), rb_intern("to_s"), 0));
+    if (BOX_ROOT_P(box)) {
+        rb_str_cat_cstr(r, ",root");
+    }
+    if (BOX_USER_P(box)) {
+        rb_str_cat_cstr(r, ",user");
+    }
+    if (BOX_MAIN_P(box)) {
+        rb_str_cat_cstr(r, ",main");
+    }
+    else if (BOX_OPTIONAL_P(box)) {
+        rb_str_cat_cstr(r, ",optional");
+    }
+    rb_str_cat_cstr(r, ">");
+    return r;
+}
+
+static VALUE
+rb_box_loading_func(int argc, VALUE *argv, VALUE _self)
+{
+    rb_vm_frame_flag_set_box_require(GET_EC());
+    return rb_call_super(argc, argv);
+}
+
+static void
+box_define_loader_method(const char *name)
+{
+    rb_define_private_method(rb_mBoxLoader, name, rb_box_loading_func, -1);
+    rb_define_singleton_method(rb_mBoxLoader, name, rb_box_loading_func, -1);
+}
+
+void
+Init_root_box(void)
+{
+    root_box->loading_table = st_init_strtable();
+}
+
+void
+Init_enable_box(void)
+{
+    const char *env = getenv("RUBY_BOX");
+    if (env && strlen(env) == 1 && env[0] == '1') {
+        ruby_box_enabled = true;
+    }
+    else {
+        ruby_box_init_done = true;
+    }
+}
+
+/* :nodoc: */
+static VALUE
+rb_box_s_root(VALUE recv)
+{
+    return root_box->box_object;
+}
+
+/* :nodoc: */
+static VALUE
+rb_box_s_main(VALUE recv)
+{
+    return main_box->box_object;
+}
+
+/* :nodoc: */
+static VALUE
+rb_box_root_p(VALUE box_value)
+{
+    const rb_box_t *box = (const rb_box_t *)rb_get_box_t(box_value);
+    return RBOOL(BOX_ROOT_P(box));
+}
+
+/* :nodoc: */
+static VALUE
+rb_box_main_p(VALUE box_value)
+{
+    const rb_box_t *box = (const rb_box_t *)rb_get_box_t(box_value);
+    return RBOOL(BOX_MAIN_P(box));
+}
+
+#if RUBY_DEBUG
+
+static const char *
+classname(VALUE klass)
+{
+    VALUE p;
+    if (!klass) {
+        return "Qfalse";
+    }
+    p = RCLASSEXT_CLASSPATH(RCLASS_EXT_PRIME(klass));
+    if (RTEST(p))
+        return RSTRING_PTR(p);
+    if (RB_TYPE_P(klass, T_CLASS) || RB_TYPE_P(klass, T_MODULE) || RB_TYPE_P(klass, T_ICLASS))
+        return "AnyClassValue";
+    return "NonClassValue";
+}
+
+static enum rb_id_table_iterator_result
+dump_classext_methods_i(ID mid, VALUE _val, void *data)
+{
+    VALUE ary = (VALUE)data;
+    rb_ary_push(ary, rb_id2str(mid));
+    return ID_TABLE_CONTINUE;
+}
+
+static enum rb_id_table_iterator_result
+dump_classext_constants_i(ID mid, VALUE _val, void *data)
+{
+    VALUE ary = (VALUE)data;
+    rb_ary_push(ary, rb_id2str(mid));
+    return ID_TABLE_CONTINUE;
+}
+
+static void
+dump_classext_i(rb_classext_t *ext, bool is_prime, VALUE _recv, void *data)
+{
+    char buf[4096];
+    struct rb_id_table *tbl;
+    VALUE ary, res = (VALUE)data;
+
+    snprintf(buf, 4096, "Ruby::Box %ld:%s classext %p\n",
+             RCLASSEXT_BOX(ext)->box_id, is_prime ? " prime" : "", (void *)ext);
+    rb_str_cat_cstr(res, buf);
+
+    snprintf(buf, 2048, "  Super: %s\n", classname(RCLASSEXT_SUPER(ext)));
+    rb_str_cat_cstr(res, buf);
+
+    tbl = RCLASSEXT_M_TBL(ext);
+    if (tbl) {
+        ary = rb_ary_new_capa((long)rb_id_table_size(tbl));
+        rb_id_table_foreach(RCLASSEXT_M_TBL(ext), dump_classext_methods_i, (void *)ary);
+        rb_ary_sort_bang(ary);
+        snprintf(buf, 4096, "  Methods(%ld): ", RARRAY_LEN(ary));
+        rb_str_cat_cstr(res, buf);
+        rb_str_concat(res, rb_ary_join(ary, rb_str_new_cstr(",")));
+        rb_str_cat_cstr(res, "\n");
+    }
+    else {
+        rb_str_cat_cstr(res, "  Methods(0): .\n");
+    }
+
+    tbl = RCLASSEXT_CONST_TBL(ext);
+    if (tbl) {
+        ary = rb_ary_new_capa((long)rb_id_table_size(tbl));
+        rb_id_table_foreach(tbl, dump_classext_constants_i, (void *)ary);
+        rb_ary_sort_bang(ary);
+        snprintf(buf, 4096, "  Constants(%ld): ", RARRAY_LEN(ary));
+        rb_str_cat_cstr(res, buf);
+        rb_str_concat(res, rb_ary_join(ary, rb_str_new_cstr(",")));
+        rb_str_cat_cstr(res, "\n");
+    }
+    else {
+        rb_str_cat_cstr(res, "  Constants(0): .\n");
+    }
+}
+
+/* :nodoc: */
+static VALUE
+rb_f_dump_classext(VALUE recv, VALUE klass)
+{
+    /*
+     * The desired output String value is:
+     * Class: 0x88800932 (String) [singleton]
+     * Prime classext box(2,main), readable(t), writable(f)
+     * Non-prime classexts: 3
+     * Box 2: prime classext 0x88800933
+     *   Super: Object
+     *   Methods(43): aaaaa, bbbb, cccc, dddd, eeeee, ffff, gggg, hhhhh, ...
+     *   Constants(12): FOO, Bar, ...
+     * Box 5: classext 0x88800934
+     *   Super: Object
+     *   Methods(43): aaaaa, bbbb, cccc, dddd, eeeee, ffff, gggg, hhhhh, ...
+     *   Constants(12): FOO, Bar, ...
+     */
+    char buf[2048];
+    VALUE res;
+    const rb_classext_t *ext;
+    const rb_box_t *box;
+    st_table *classext_tbl;
+
+    if (!(RB_TYPE_P(klass, T_CLASS) || RB_TYPE_P(klass, T_MODULE))) {
+        snprintf(buf, 2048, "Non-class/module value: %p (%s)\n", (void *)klass, rb_type_str(BUILTIN_TYPE(klass)));
+        return rb_str_new_cstr(buf);
+    }
+
+    if (RB_TYPE_P(klass, T_CLASS)) {
+        snprintf(buf, 2048, "Class: %p (%s)%s\n",
+                 (void *)klass, classname(klass), RCLASS_SINGLETON_P(klass) ? " [singleton]" : "");
+    }
+    else {
+        snprintf(buf, 2048, "Module: %p (%s)\n", (void *)klass, classname(klass));
+    }
+    res = rb_str_new_cstr(buf);
+
+    ext = RCLASS_EXT_PRIME(klass);
+    box = RCLASSEXT_BOX(ext);
+    snprintf(buf, 2048, "Prime classext box(%ld,%s), readable(%s), writable(%s)\n",
+             box->box_id,
+             BOX_ROOT_P(box) ? "root" : (BOX_MAIN_P(box) ? "main" : "optional"),
+             RCLASS_PRIME_CLASSEXT_READABLE_P(klass) ? "t" : "f",
+             RCLASS_PRIME_CLASSEXT_WRITABLE_P(klass) ? "t" : "f");
+    rb_str_cat_cstr(res, buf);
+
+    classext_tbl = RCLASS_CLASSEXT_TBL(klass);
+    if (!classext_tbl) {
+        rb_str_cat_cstr(res, "Non-prime classexts: 0\n");
+    }
+    else {
+        snprintf(buf, 2048, "Non-prime classexts: %zu\n", st_table_size(classext_tbl));
+        rb_str_cat_cstr(res, buf);
+    }
+
+    rb_class_classext_foreach(klass, dump_classext_i, (void *)res);
+
+    return res;
+}
+
+#endif /* RUBY_DEBUG */
+
+/*
+ *  Document-class: Ruby::Box
+ *
+ *  :markup: markdown
+ *  :include: doc/language/box.md
+ */
+void
+Init_Box(void)
+{
+    tmp_dir = system_tmpdir();
+    tmp_dir_has_dirsep = (strcmp(tmp_dir + (strlen(tmp_dir) - strlen(DIRSEP)), DIRSEP) == 0);
+
+    VALUE mRuby = rb_define_module("Ruby");
+
+    rb_cBox = rb_define_class_under(mRuby, "Box", rb_cModule);
+    rb_define_method(rb_cBox, "initialize", box_initialize, 0);
+
+    /* :nodoc: */
+    rb_cBoxEntry = rb_define_class_under(rb_cBox, "Entry", rb_cObject);
+    rb_define_alloc_func(rb_cBoxEntry, rb_box_entry_alloc);
+
+    initialize_root_box();
+
+    /* :nodoc: */
+    rb_mBoxLoader = rb_define_module_under(rb_cBox, "Loader");
+    box_define_loader_method("require");
+    box_define_loader_method("require_relative");
+    box_define_loader_method("load");
+
+    if (rb_box_available()) {
+        rb_include_module(rb_cObject, rb_mBoxLoader);
+
+        rb_define_singleton_method(rb_cBox, "root", rb_box_s_root, 0);
+        rb_define_singleton_method(rb_cBox, "main", rb_box_s_main, 0);
+        rb_define_method(rb_cBox, "root?", rb_box_root_p, 0);
+        rb_define_method(rb_cBox, "main?", rb_box_main_p, 0);
+
+#if RUBY_DEBUG
+        rb_define_global_function("dump_classext", rb_f_dump_classext, 1);
+#endif
+    }
+
+    rb_define_singleton_method(rb_cBox, "enabled?", rb_box_s_getenabled, 0);
+    rb_define_singleton_method(rb_cBox, "current", rb_box_s_current, 0);
+
+    rb_define_method(rb_cBox, "load_path", rb_box_load_path, 0);
+    rb_define_method(rb_cBox, "load", rb_box_load, -1);
+    rb_define_method(rb_cBox, "require", rb_box_require, 1);
+    rb_define_method(rb_cBox, "require_relative", rb_box_require_relative, 1);
+    rb_define_method(rb_cBox, "eval", rb_box_eval, 1);
+
+    rb_define_method(rb_cBox, "inspect", rb_box_inspect, 0);
+}
diff --git a/builtin.c b/builtin.c
index 21fff95650..6cc9790466 100644
--- a/builtin.c
+++ b/builtin.c
@@ -3,15 +3,15 @@
 #include "iseq.h"
 #include "builtin.h"
 
-#ifdef CROSS_COMPILING
+#include "builtin_binary.rbbin"
 
-#define INCLUDED_BY_BUILTIN_C 1
+#ifndef BUILTIN_BINARY_SIZE
+
+#define BUILTIN_LOADED(feature_name, iseq) ((void)0)
 #include "mini_builtin.c"
 
 #else
 
-#include "builtin_binary.inc"
-
 static const unsigned char *
 bin4feature(const struct builtin_binary *bb, const char *feature, size_t *psize)
 {
@@ -32,31 +32,43 @@ builtin_lookup(const char *feature, size_t *psize)
     return bin;
 }
 
-void
-rb_load_with_builtin_functions(const char *feature_name, const struct rb_builtin_function *table)
+static void
+load_with_builtin_functions(const char *feature_name, const struct rb_builtin_function *table)
 {
     // search binary
     size_t size;
     const unsigned char *bin = builtin_lookup(feature_name, &size);
     if (! bin) {
-        rb_bug("builtin_lookup: can not find %s\n", feature_name);
+        rb_bug("builtin_lookup: can not find %s", feature_name);
     }
 
     // load binary
     rb_vm_t *vm = GET_VM();
     if (vm->builtin_function_table != NULL) rb_bug("vm->builtin_function_table should be NULL.");
     vm->builtin_function_table = table;
-    vm->builtin_inline_index = 0;
     const rb_iseq_t *iseq = rb_iseq_ibf_load_bytes((const char *)bin, size);
+    ASSUME(iseq); // otherwise an exception should have raised
     vm->builtin_function_table = NULL;
 
     // exec
-    rb_iseq_eval(rb_iseq_check(iseq));
+    rb_iseq_eval(rb_iseq_check(iseq), rb_root_box()); // builtin functions are loaded in the root box
+}
+
+void
+rb_load_with_builtin_functions(const char *feature_name, const struct rb_builtin_function *table)
+{
+    load_with_builtin_functions(feature_name, table);
 }
 
 #endif
 
 void
+rb_free_loaded_builtin_table(void)
+{
+    // do nothing
+}
+
+void
 Init_builtin(void)
 {
     // nothing
@@ -65,5 +77,11 @@ Init_builtin(void)
 void
 Init_builtin_features(void)
 {
-    rb_load_with_builtin_functions("gem_prelude", NULL);
+
+#ifdef BUILTIN_BINARY_SIZE
+
+    load_with_builtin_functions("gem_prelude", NULL);
+
+#endif
+
 }
diff --git a/builtin.h b/builtin.h
index 7ad52f44f4..fd1c4c307f 100644
--- a/builtin.h
+++ b/builtin.h
@@ -11,17 +11,13 @@ struct rb_builtin_function {
     // for load
     const int index;
     const char * const name;
-
-    // for jit
-    void (*compiler)(FILE *, long, unsigned, bool);
 };
 
-#define RB_BUILTIN_FUNCTION(_i, _name, _fname, _arity, _compiler) {\
+#define RB_BUILTIN_FUNCTION(_i, _name, _fname, _arity) {\
   .name = _i < 0 ? NULL : #_name, \
-  .func_ptr = (void *)_fname, \
+  .func_ptr = (void *)(uintptr_t)_fname, \
   .argc = _arity, \
   .index = _i, \
-  .compiler = _compiler, \
 }
 
 void rb_load_with_builtin_functions(const char *feature_name, const struct rb_builtin_function *table);
@@ -110,6 +106,14 @@ rb_vm_lvar(rb_execution_context_t *ec, int index)
 #endif
 }
 
+static inline VALUE
+rb_builtin_basic_definition_p(rb_execution_context_t *ec, VALUE klass, VALUE id_sym)
+{
+    return rb_method_basic_definition_p(klass, rb_sym2id(id_sym)) ? Qtrue : Qfalse;
+}
+
+#define LOCAL_PTR(local) local ## __ptr
+
 // dump/load
 
 struct builtin_binary {
diff --git a/ccan/check_type/check_type.h b/ccan/check_type/check_type.h
index e795ad71d0..659e1a5a83 100644
--- a/ccan/check_type/check_type.h
+++ b/ccan/check_type/check_type.h
@@ -44,7 +44,7 @@
  *		 ((encl_type *)						\
  *		  ((char *)(mbr_ptr) - offsetof(enclosing_type, mbr))))
  */
-#if HAVE_TYPEOF
+#if defined(HAVE_TYPEOF) && HAVE_TYPEOF
 #define ccan_check_type(expr, type)			\
 	((typeof(expr) *)0 != (type *)0)
 
diff --git a/ccan/container_of/container_of.h b/ccan/container_of/container_of.h
index b30c347d57..872bb6ea6e 100644
--- a/ccan/container_of/container_of.h
+++ b/ccan/container_of/container_of.h
@@ -112,7 +112,7 @@ static inline char *container_of_or_null_(void *member_ptr, size_t offset)
  *		return i;
  *	}
  */
-#if HAVE_TYPEOF
+#if defined(HAVE_TYPEOF) && HAVE_TYPEOF
 #define ccan_container_of_var(member_ptr, container_var, member) \
 	ccan_container_of(member_ptr, typeof(*container_var), member)
 #else
@@ -131,7 +131,7 @@ static inline char *container_of_or_null_(void *member_ptr, size_t offset)
  * structure memory layout.
  *
  */
-#if HAVE_TYPEOF
+#if defined(HAVE_TYPEOF) && HAVE_TYPEOF
 #define ccan_container_off_var(var, member)		\
 	ccan_container_off(typeof(*var), member)
 #else
diff --git a/ccan/list/list.h b/ccan/list/list.h
index 91787bfdb3..bf692a6937 100644
--- a/ccan/list/list.h
+++ b/ccan/list/list.h
@@ -635,14 +635,16 @@ static inline void ccan_list_prepend_list_(struct ccan_list_head *to,
 
 /* internal macros, do not use directly */
 #define ccan_list_for_each_off_dir_(h, i, off, dir)				\
-	for (i = ccan_list_node_to_off_(ccan_list_debug(h, CCAN_LIST_LOC)->n.dir,	\
+	for (i = 0, \
+	     i = ccan_list_node_to_off_(ccan_list_debug(h, CCAN_LIST_LOC)->n.dir, \
 				   (off));				\
 	ccan_list_node_from_off_((void *)i, (off)) != &(h)->n;		\
 	i = ccan_list_node_to_off_(ccan_list_node_from_off_((void *)i, (off))->dir, \
 			      (off)))
 
 #define ccan_list_for_each_safe_off_dir_(h, i, nxt, off, dir)		\
-	for (i = ccan_list_node_to_off_(ccan_list_debug(h, CCAN_LIST_LOC)->n.dir,	\
+	for (i = 0, \
+	     i = ccan_list_node_to_off_(ccan_list_debug(h, CCAN_LIST_LOC)->n.dir, \
 				   (off)),				\
 	nxt = ccan_list_node_to_off_(ccan_list_node_from_off_(i, (off))->dir,	\
 				(off));					\
@@ -770,7 +772,7 @@ static inline struct ccan_list_node *ccan_list_node_from_off_(void *ptr, size_t
 	(ccan_container_off_var(var, member) +		\
 	 ccan_check_type(var->member, struct ccan_list_node))
 
-#if HAVE_TYPEOF
+#if defined(HAVE_TYPEOF) && HAVE_TYPEOF
 #define ccan_list_typeof(var) typeof(var)
 #else
 #define ccan_list_typeof(var) void *
diff --git a/class.c b/class.c
index 5e57068f03..9c1bd86dc3 100644
--- a/class.c
+++ b/class.c
@@ -21,6 +21,7 @@
 #include "debug_counter.h"
 #include "id_table.h"
 #include "internal.h"
+#include "internal/box.h"
 #include "internal/class.h"
 #include "internal/eval.h"
 #include "internal/hash.h"
@@ -29,130 +30,700 @@
 #include "internal/variable.h"
 #include "ruby/st.h"
 #include "vm_core.h"
+#include "ruby/ractor.h"
+#include "yjit.h"
+#include "zjit.h"
 
-#define id_attached id__attached__
+/* Flags of T_CLASS
+ *
+ * 0:    RCLASS_IS_ROOT
+ *           The class has been added to the VM roots. Will always be marked and pinned.
+ *           This is done for classes defined from C to allow storing them in global variables.
+ * 1:    RUBY_FL_SINGLETON
+ *           This class is a singleton class.
+ * 2:    RCLASS_PRIME_CLASSEXT_PRIME_WRITABLE
+ *           This class's prime classext is the only classext and writable from any boxes.
+ *           If unset, the prime classext is writable only from the root box.
+ * 3:    RCLASS_IS_INITIALIZED
+ *           Class has been initialized.
+ * 4:    RCLASS_BOXABLE
+ *           Is a builtin class that may be boxed. It larger than a normal class.
+ */
+
+/* Flags of T_ICLASS
+ *
+ * 2:    RCLASS_PRIME_CLASSEXT_PRIME_WRITABLE
+ *           This module's prime classext is the only classext and writable from any boxes.
+ *           If unset, the prime classext is writable only from the root box.
+ * 4:    RCLASS_BOXABLE
+ *           Is a builtin class that may be boxed. It larger than a normal class.
+ */
+
+/* Flags of T_MODULE
+ *
+ * 0:    RCLASS_IS_ROOT
+ *           The class has been added to the VM roots. Will always be marked and pinned.
+ *           This is done for classes defined from C to allow storing them in global variables.
+ * 1:    <reserved>
+ *          Ensures that RUBY_FL_SINGLETON is never set on a T_MODULE. See `rb_class_real`.
+ * 2:    RCLASS_PRIME_CLASSEXT_PRIME_WRITABLE
+ *           This module's prime classext is the only classext and writable from any boxes.
+ *           If unset, the prime classext is writable only from the root box.
+ * 3:    RCLASS_IS_INITIALIZED
+ *           Module has been initialized.
+ * 4:    RCLASS_BOXABLE
+ *           Is a builtin class that may be boxed. It larger than a normal class.
+ * 5:    RMODULE_IS_REFINEMENT
+ *           Module is used for refinements.
+ */
 
 #define METACLASS_OF(k) RBASIC(k)->klass
 #define SET_METACLASS_OF(k, cls) RBASIC_SET_CLASS(k, cls)
 
-RUBY_EXTERN rb_serial_t ruby_vm_global_cvar_state;
+static enum rb_id_table_iterator_result
+cvar_table_free_i(VALUE value, void *ctx)
+{
+    xfree((void *)value);
+    return ID_TABLE_CONTINUE;
+}
 
-static rb_subclass_entry_t *
-push_subclass_entry_to_list(VALUE super, VALUE klass)
+rb_classext_t *
+rb_class_unlink_classext(VALUE klass, const rb_box_t *box)
 {
-    rb_subclass_entry_t *entry, *head;
+    st_data_t ext;
+    st_data_t key = (st_data_t)box->box_object;
+    VALUE obj_id = rb_obj_id(klass);
+    st_delete(box->classext_cow_classes, &obj_id, 0);
+    st_delete(RCLASS_CLASSEXT_TBL(klass), &key, &ext);
+    return (rb_classext_t *)ext;
+}
 
-    entry = ZALLOC(rb_subclass_entry_t);
-    entry->klass = klass;
+void
+rb_class_classext_free(VALUE klass, rb_classext_t *ext, bool is_prime)
+{
+    struct rb_id_table *tbl;
 
-    head = RCLASS_SUBCLASSES(super);
-    if (!head) {
-        head = ZALLOC(rb_subclass_entry_t);
-        RCLASS_SUBCLASSES(super) = head;
+    rb_id_table_free(RCLASSEXT_M_TBL(ext));
+
+    if (!RCLASSEXT_SHARED_CONST_TBL(ext) && (tbl = RCLASSEXT_CONST_TBL(ext)) != NULL) {
+        rb_free_const_table(tbl);
+    }
+
+    if ((tbl = RCLASSEXT_CVC_TBL(ext)) != NULL) {
+        rb_id_table_foreach_values(tbl, cvar_table_free_i, NULL);
+        rb_id_table_free(tbl);
     }
-    entry->next = head->next;
-    entry->prev = head;
 
-    if (head->next) {
-        head->next->prev = entry;
+    rb_class_classext_free_subclasses(ext, klass, false);
+
+    if (RCLASSEXT_SUPERCLASSES_WITH_SELF(ext)) {
+        RUBY_ASSERT(is_prime); // superclasses should only be used on prime
+        xfree(RCLASSEXT_SUPERCLASSES(ext));
     }
-    head->next = entry;
 
-    return entry;
+    if (!is_prime) { // the prime classext will be freed with RClass
+        xfree(ext);
+    }
 }
 
 void
-rb_class_subclass_add(VALUE super, VALUE klass)
+rb_iclass_classext_free(VALUE klass, rb_classext_t *ext, bool is_prime)
 {
-    if (super && super != Qundef) {
-        rb_subclass_entry_t *entry = push_subclass_entry_to_list(super, klass);
-        RCLASS_SUBCLASS_ENTRY(klass) = entry;
+    if (RCLASSEXT_ICLASS_IS_ORIGIN(ext) && !RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(ext)) {
+        /* Method table is not shared for origin iclasses of classes */
+        rb_id_table_free(RCLASSEXT_M_TBL(ext));
+    }
+
+    if (RCLASSEXT_CALLABLE_M_TBL(ext) != NULL) {
+        rb_id_table_free(RCLASSEXT_CALLABLE_M_TBL(ext));
+    }
+
+    rb_class_classext_free_subclasses(ext, klass, false);
+
+    if (!is_prime) { // the prime classext will be freed with RClass
+        xfree(ext);
     }
 }
 
 static void
-rb_module_add_to_subclasses_list(VALUE module, VALUE iclass)
+iclass_free_orphan_classext(VALUE klass, rb_classext_t *ext)
 {
-    rb_subclass_entry_t *entry = push_subclass_entry_to_list(module, iclass);
-    RCLASS_MODULE_SUBCLASS_ENTRY(iclass) = entry;
+    if (RCLASSEXT_ICLASS_IS_ORIGIN(ext) && !RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(ext)) {
+        /* Method table is not shared for origin iclasses of classes */
+        rb_id_table_free(RCLASSEXT_M_TBL(ext));
+    }
+
+    if (RCLASSEXT_CALLABLE_M_TBL(ext) != NULL) {
+        rb_id_table_free(RCLASSEXT_CALLABLE_M_TBL(ext));
+    }
+
+    rb_class_classext_free_subclasses(ext, klass, true); // replacing this classext with a newer one
+
+    xfree(ext);
 }
 
-void
-rb_class_remove_subclass_head(VALUE klass)
+struct rb_class_set_box_classext_args {
+    VALUE obj;
+    rb_classext_t *ext;
+};
+
+static int
+set_box_classext_update(st_data_t *key_ptr, st_data_t *val_ptr, st_data_t a, int existing)
 {
-    rb_subclass_entry_t *head = RCLASS_SUBCLASSES(klass);
+    struct rb_class_set_box_classext_args *args = (struct rb_class_set_box_classext_args *)a;
 
-    if (head) {
-        if (head->next) {
-            head->next->prev = NULL;
+    if (existing) {
+        if (LIKELY(BUILTIN_TYPE(args->obj) == T_ICLASS)) {
+            iclass_free_orphan_classext(args->obj, (rb_classext_t *)*val_ptr);
+        }
+        else {
+            rb_bug("Updating existing classext for non-iclass never happen");
         }
-        RCLASS_SUBCLASSES(klass) = NULL;
-        xfree(head);
     }
+
+    *val_ptr = (st_data_t)args->ext;
+
+    return ST_CONTINUE;
 }
 
 void
-rb_class_remove_from_super_subclasses(VALUE klass)
+rb_class_set_box_classext(VALUE obj, const rb_box_t *box, rb_classext_t *ext)
+{
+    struct rb_class_set_box_classext_args args = {
+        .obj = obj,
+        .ext = ext,
+    };
+
+    VM_ASSERT(BOX_USER_P(box));
+
+    st_update(RCLASS_CLASSEXT_TBL(obj), (st_data_t)box->box_object, set_box_classext_update, (st_data_t)&args);
+    st_insert(box->classext_cow_classes, (st_data_t)rb_obj_id(obj), obj);
+
+    // FIXME: This is done here because this is the first time the objects in
+    // the classext are exposed via this class. It's likely that if GC
+    // compaction occurred between the VALUEs being copied in and this
+    // writebarrier trigger the values will be stale.
+    rb_gc_writebarrier_remember(obj);
+}
+
+RUBY_EXTERN rb_serial_t ruby_vm_global_cvar_state;
+
+struct duplicate_id_tbl_data {
+    struct rb_id_table *tbl;
+    VALUE klass;
+};
+
+static enum rb_id_table_iterator_result
+duplicate_classext_id_table_i(ID key, VALUE value, void *data)
+{
+    struct rb_id_table *tbl = (struct rb_id_table *)data;
+    rb_id_table_insert(tbl, key, value);
+    return ID_TABLE_CONTINUE;
+}
+
+static enum rb_id_table_iterator_result
+duplicate_classext_m_tbl_i(ID key, VALUE value, void *data)
+{
+    struct duplicate_id_tbl_data *arg = (struct duplicate_id_tbl_data *)data;
+    rb_method_entry_t *me = (rb_method_entry_t *)value;
+    rb_method_table_insert0(arg->klass, arg->tbl, key, me, false);
+    return ID_TABLE_CONTINUE;
+}
+
+static struct rb_id_table *
+duplicate_classext_m_tbl(struct rb_id_table *orig, VALUE klass, bool init_missing)
+{
+    struct rb_id_table *tbl;
+    if (!orig) {
+        if (init_missing)
+            return rb_id_table_create(0);
+        else
+            return NULL;
+    }
+    tbl = rb_id_table_create(rb_id_table_size(orig));
+    struct duplicate_id_tbl_data data = {
+        .tbl = tbl,
+        .klass = klass,
+    };
+    rb_id_table_foreach(orig, duplicate_classext_m_tbl_i, &data);
+    return tbl;
+}
+
+static struct rb_id_table *
+duplicate_classext_id_table(struct rb_id_table *orig, bool init_missing)
+{
+    struct rb_id_table *tbl;
+
+    if (!orig) {
+        if (init_missing)
+            return rb_id_table_create(0);
+        else
+            return NULL;
+    }
+    tbl = rb_id_table_create(rb_id_table_size(orig));
+    rb_id_table_foreach(orig, duplicate_classext_id_table_i, tbl);
+    return tbl;
+}
+
+static rb_const_entry_t *
+duplicate_classext_const_entry(rb_const_entry_t *src, VALUE klass)
+{
+    // See also: setup_const_entry (variable.c)
+    rb_const_entry_t *dst = ZALLOC(rb_const_entry_t);
+
+    dst->flag = src->flag;
+    dst->line = src->line;
+    RB_OBJ_WRITE(klass, &dst->value, src->value);
+    RB_OBJ_WRITE(klass, &dst->file, src->file);
+
+    return dst;
+}
+
+static enum rb_id_table_iterator_result
+duplicate_classext_const_tbl_i(ID key, VALUE value, void *data)
+{
+    struct duplicate_id_tbl_data *arg = (struct duplicate_id_tbl_data *)data;
+    rb_const_entry_t *entry = duplicate_classext_const_entry((rb_const_entry_t *)value, arg->klass);
+
+    rb_id_table_insert(arg->tbl, key, (VALUE)entry);
+
+    return ID_TABLE_CONTINUE;
+}
+
+static struct rb_id_table *
+duplicate_classext_const_tbl(struct rb_id_table *src, VALUE klass)
+{
+    struct rb_id_table *dst;
+
+    if (!src)
+        return NULL;
+
+    dst = rb_id_table_create(rb_id_table_size(src));
+
+    struct duplicate_id_tbl_data data = {
+        .tbl = dst,
+        .klass = klass,
+    };
+    rb_id_table_foreach(src, duplicate_classext_const_tbl_i, (void *)&data);
+
+    return dst;
+}
+
+static VALUE
+box_subclasses_tbl_key(const rb_box_t *box)
 {
-    rb_subclass_entry_t *entry = RCLASS_SUBCLASS_ENTRY(klass);
+    if (!box){
+        return 0;
+    }
+    return (VALUE)box->box_id;
+}
 
-    if (entry) {
-        rb_subclass_entry_t *prev = entry->prev, *next = entry->next;
+static void
+duplicate_classext_subclasses(rb_classext_t *orig, rb_classext_t *copy)
+{
+    rb_subclass_anchor_t *anchor, *orig_anchor;
+    rb_subclass_entry_t *head, *cur, *cdr, *entry, *first = NULL;
+    rb_box_subclasses_t *box_subclasses;
+    struct st_table *tbl;
 
-        if (prev) {
-            prev->next = next;
+    if (RCLASSEXT_SUBCLASSES(orig)) {
+        orig_anchor = RCLASSEXT_SUBCLASSES(orig);
+        box_subclasses = orig_anchor->box_subclasses;
+        tbl = ((rb_box_subclasses_t *)box_subclasses)->tbl;
+
+        anchor = ZALLOC(rb_subclass_anchor_t);
+        anchor->box_subclasses = rb_box_subclasses_ref_inc(box_subclasses);
+
+        head = ZALLOC(rb_subclass_entry_t);
+        anchor->head = head;
+
+        RCLASSEXT_SUBCLASSES(copy) = anchor;
+
+        cur = head;
+        entry = orig_anchor->head;
+        RUBY_ASSERT(!entry->klass);
+        // The head entry has NULL klass always. See rb_class_foreach_subclass().
+        entry = entry->next;
+        while (entry) {
+            if (rb_objspace_garbage_object_p(entry->klass)) {
+                entry = entry->next;
+                continue;
+            }
+            cdr = ZALLOC(rb_subclass_entry_t);
+            cdr->klass = entry->klass;
+            cdr->prev = cur;
+            cur->next = cdr;
+            if (!first) {
+                VALUE box_id = box_subclasses_tbl_key(RCLASSEXT_BOX(copy));
+                first = cdr;
+                st_insert(tbl, box_id, (st_data_t)first);
+            }
+            cur = cdr;
+            entry = entry->next;
         }
-        if (next) {
-            next->prev = prev;
+    }
+
+    if (RCLASSEXT_BOX_SUPER_SUBCLASSES(orig))
+        RCLASSEXT_BOX_SUPER_SUBCLASSES(copy) = rb_box_subclasses_ref_inc(RCLASSEXT_BOX_SUPER_SUBCLASSES(orig));
+    if (RCLASSEXT_BOX_MODULE_SUBCLASSES(orig))
+        RCLASSEXT_BOX_MODULE_SUBCLASSES(copy) = rb_box_subclasses_ref_inc(RCLASSEXT_BOX_MODULE_SUBCLASSES(orig));
+}
+
+static void
+class_duplicate_iclass_classext(VALUE iclass, rb_classext_t *mod_ext, const rb_box_t *box)
+{
+    RUBY_ASSERT(RB_TYPE_P(iclass, T_ICLASS));
+
+    rb_classext_t *src = RCLASS_EXT_PRIME(iclass);
+    rb_classext_t *ext = RCLASS_EXT_TABLE_LOOKUP_INTERNAL(iclass, box);
+    int first_set = 0;
+
+    if (ext) {
+        // iclass classext for the ns is only for cc/callable_m_tbl if it's created earlier than module's one
+        rb_invalidate_method_caches(RCLASSEXT_CALLABLE_M_TBL(ext), RCLASSEXT_CC_TBL(ext));
+    }
+
+    ext = ZALLOC(rb_classext_t);
+
+    RCLASSEXT_BOX(ext) = box;
+
+    RCLASSEXT_SUPER(ext) = RCLASSEXT_SUPER(src);
+
+    // See also: rb_include_class_new()
+    if (RCLASSEXT_ICLASS_IS_ORIGIN(src) && !RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(src)) {
+        RCLASSEXT_M_TBL(ext) = duplicate_classext_m_tbl(RCLASSEXT_M_TBL(src), iclass, true);
+    }
+    else {
+        RCLASSEXT_M_TBL(ext) = RCLASSEXT_M_TBL(mod_ext);
+    }
+
+    RCLASSEXT_CONST_TBL(ext) = RCLASSEXT_CONST_TBL(mod_ext);
+    RCLASSEXT_CVC_TBL(ext) = RCLASSEXT_CVC_TBL(mod_ext);
+
+    // Those are cache and should be recreated when methods are called
+    // RCLASSEXT_CALLABLE_M_TBL(ext) = NULL;
+    // RCLASSEXT_CC_TBL(ext) = NULL;
+
+    // subclasses, box_super_subclasses_tbl, box_module_subclasses_tbl
+    duplicate_classext_subclasses(src, ext);
+
+    RCLASSEXT_SET_ORIGIN(ext, iclass, RCLASSEXT_ORIGIN(src));
+    RCLASSEXT_ICLASS_IS_ORIGIN(ext) = RCLASSEXT_ICLASS_IS_ORIGIN(src);
+    RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(ext) = RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(src);
+
+    RCLASSEXT_SET_INCLUDER(ext, iclass, RCLASSEXT_INCLUDER(src));
+
+    VM_ASSERT(FL_TEST_RAW(iclass, RCLASS_BOXABLE));
+
+    first_set = RCLASS_SET_BOX_CLASSEXT(iclass, box, ext);
+    if (first_set) {
+        RCLASS_SET_PRIME_CLASSEXT_WRITABLE(iclass, false);
+    }
+}
+
+rb_classext_t *
+rb_class_duplicate_classext(rb_classext_t *orig, VALUE klass, const rb_box_t *box)
+{
+    VM_ASSERT(RB_TYPE_P(klass, T_CLASS) || RB_TYPE_P(klass, T_MODULE) || RB_TYPE_P(klass, T_ICLASS));
+
+    rb_classext_t *ext = ZALLOC(rb_classext_t);
+    bool dup_iclass = RB_TYPE_P(klass, T_MODULE) ? true : false;
+
+    RCLASSEXT_BOX(ext) = box;
+
+    RCLASSEXT_SUPER(ext) = RCLASSEXT_SUPER(orig);
+
+    RCLASSEXT_M_TBL(ext) = duplicate_classext_m_tbl(RCLASSEXT_M_TBL(orig), klass, dup_iclass);
+    RCLASSEXT_ICLASS_IS_ORIGIN(ext) = true;
+    RCLASSEXT_ICLASS_ORIGIN_SHARED_MTBL(ext) = false;
+
+    if (orig->fields_obj) {
+        RB_OBJ_WRITE(klass, &ext->fields_obj, rb_imemo_fields_clone(orig->fields_obj));
+    }
+
+    if (RCLASSEXT_SHARED_CONST_TBL(orig)) {
+        RCLASSEXT_CONST_TBL(ext) = RCLASSEXT_CONST_TBL(orig);
+        RCLASSEXT_SHARED_CONST_TBL(ext) = true;
+    }
+    else {
+        RCLASSEXT_CONST_TBL(ext) = duplicate_classext_const_tbl(RCLASSEXT_CONST_TBL(orig), klass);
+        RCLASSEXT_SHARED_CONST_TBL(ext) = false;
+    }
+    /*
+     * callable_m_tbl is for `super` chain, and entries will be created when the super chain is called.
+     * so initially, it can be NULL and let it be created lazily.
+     * RCLASSEXT_CALLABLE_M_TBL(ext) = NULL;
+     *
+     * cc_tbl is for method inline cache, and method calls from different boxes never occur on
+     * the same code, so the copied classext should have a different cc_tbl from the prime one.
+     * RCLASSEXT_CC_TBL(copy) = NULL
+     */
+
+    RCLASSEXT_CVC_TBL(ext) = duplicate_classext_id_table(RCLASSEXT_CVC_TBL(orig), dup_iclass);
+
+    // subclasses, subclasses_index
+    duplicate_classext_subclasses(orig, ext);
+
+    RCLASSEXT_SET_ORIGIN(ext, klass, RCLASSEXT_ORIGIN(orig));
+    /*
+     * Members not copied to box's classext values
+     * * refined_class
+     * * as.class.allocator / as.singleton_class.attached_object
+     * * includer
+     * * max IV count
+     * * variation count
+     */
+    RCLASSEXT_PERMANENT_CLASSPATH(ext) = RCLASSEXT_PERMANENT_CLASSPATH(orig);
+    RCLASSEXT_CLONED(ext) = RCLASSEXT_CLONED(orig);
+    RCLASSEXT_CLASSPATH(ext) = RCLASSEXT_CLASSPATH(orig);
+
+    /* For the usual T_CLASS/T_MODULE, iclass flags are always false */
+
+    if (dup_iclass) {
+        VALUE iclass;
+        /*
+         * ICLASS has the same m_tbl/const_tbl/cvc_tbl with the included module.
+         * So the module's classext is copied, its tables should be also referred
+         * by the ICLASS's classext for the box.
+         */
+        rb_subclass_anchor_t *anchor = RCLASSEXT_SUBCLASSES(ext);
+        rb_subclass_entry_t *subclass_entry = anchor->head;
+        while (subclass_entry) {
+            if (subclass_entry->klass && RB_TYPE_P(subclass_entry->klass, T_ICLASS)) {
+                iclass = subclass_entry->klass;
+                VM_ASSERT(RB_TYPE_P(iclass, T_ICLASS));
+                if (RBASIC_CLASS(iclass) == klass) {
+                    // Is the subclass an ICLASS including this module into another class
+                    // If so we need to re-associate it under our box with the new ext
+                    VM_ASSERT(FL_TEST_RAW(iclass, RCLASS_BOXABLE));
+                    class_duplicate_iclass_classext(iclass, ext, box);
+                }
+            }
+            subclass_entry = subclass_entry->next;
         }
+    }
 
-        xfree(entry);
+    return ext;
+}
+
+void
+rb_class_ensure_writable(VALUE klass)
+{
+    VM_ASSERT(RB_TYPE_P(klass, T_CLASS) || RB_TYPE_P(klass, T_MODULE) || RB_TYPE_P(klass, T_ICLASS));
+    RCLASS_EXT_WRITABLE(klass);
+}
+
+struct class_classext_foreach_arg {
+    rb_class_classext_foreach_callback_func *func;
+    void * callback_arg;
+};
+
+static int
+class_classext_foreach_i(st_data_t key, st_data_t value, st_data_t arg)
+{
+    struct class_classext_foreach_arg *foreach_arg = (struct class_classext_foreach_arg *)arg;
+    rb_class_classext_foreach_callback_func *func = foreach_arg->func;
+    func((rb_classext_t *)value, false, (VALUE)key, foreach_arg->callback_arg);
+    return ST_CONTINUE;
+}
+
+void
+rb_class_classext_foreach(VALUE klass, rb_class_classext_foreach_callback_func *func, void *arg)
+{
+    st_table *tbl = RCLASS_CLASSEXT_TBL(klass);
+    struct class_classext_foreach_arg foreach_arg;
+    if (tbl) {
+        foreach_arg.func = func;
+        foreach_arg.callback_arg = arg;
+        rb_st_foreach(tbl, class_classext_foreach_i, (st_data_t)&foreach_arg);
     }
+    func(RCLASS_EXT_PRIME(klass), true, (VALUE)NULL, arg);
+}
 
-    RCLASS_SUBCLASS_ENTRY(klass) = NULL;
+VALUE
+rb_class_super_of(VALUE klass)
+{
+    return RCLASS_SUPER(klass);
+}
+
+VALUE
+rb_class_singleton_p(VALUE klass)
+{
+    return RCLASS_SINGLETON_P(klass);
+}
+
+unsigned char
+rb_class_variation_count(VALUE klass)
+{
+    return RCLASS_VARIATION_COUNT(klass);
+}
+
+static void
+push_subclass_entry_to_list(VALUE super, VALUE klass, bool is_module)
+{
+    rb_subclass_entry_t *entry, *head;
+    rb_subclass_anchor_t *anchor;
+    rb_box_subclasses_t *box_subclasses;
+    struct st_table *tbl;
+    const rb_box_t *box = rb_current_box();
+
+    entry = ZALLOC(rb_subclass_entry_t);
+    entry->klass = klass;
+
+    RB_VM_LOCKING() {
+        anchor = RCLASS_WRITABLE_SUBCLASSES(super);
+        VM_ASSERT(anchor);
+        box_subclasses = (rb_box_subclasses_t *)anchor->box_subclasses;
+        VM_ASSERT(box_subclasses);
+        tbl = box_subclasses->tbl;
+        VM_ASSERT(tbl);
+
+        head = anchor->head;
+        if (head->next) {
+            head->next->prev = entry;
+            entry->next = head->next;
+        }
+        head->next = entry;
+        entry->prev = head;
+        st_insert(tbl, box_subclasses_tbl_key(box), (st_data_t)entry);
+    }
+
+    if (is_module) {
+        RCLASS_WRITE_BOX_MODULE_SUBCLASSES(klass, anchor->box_subclasses);
+    }
+    else {
+        RCLASS_WRITE_BOX_SUPER_SUBCLASSES(klass, anchor->box_subclasses);
+    }
 }
 
 void
-rb_class_remove_from_module_subclasses(VALUE klass)
+rb_class_subclass_add(VALUE super, VALUE klass)
+{
+    if (super && !UNDEF_P(super)) {
+        push_subclass_entry_to_list(super, klass, false);
+    }
+}
+
+static void
+rb_module_add_to_subclasses_list(VALUE module, VALUE iclass)
 {
-    rb_subclass_entry_t *entry = RCLASS_MODULE_SUBCLASS_ENTRY(klass);
+    if (module && !UNDEF_P(module)) {
+        push_subclass_entry_to_list(module, iclass, true);
+    }
+}
+
+static struct rb_subclass_entry *
+class_get_subclasses_for_ns(struct st_table *tbl, VALUE box_id)
+{
+    st_data_t value;
+    if (st_lookup(tbl, (st_data_t)box_id, &value)) {
+        return (struct rb_subclass_entry *)value;
+    }
+    return NULL;
+}
+
+static int
+remove_class_from_subclasses_replace_first_entry(st_data_t *key, st_data_t *value, st_data_t arg, int existing)
+{
+    *value = arg;
+    return ST_CONTINUE;
+}
+
+static void
+remove_class_from_subclasses(struct st_table *tbl, VALUE box_id, VALUE klass)
+{
+    rb_subclass_entry_t *entry = class_get_subclasses_for_ns(tbl, box_id);
+    bool first_entry = true;
+    while (entry) {
+        if (entry->klass == klass) {
+            rb_subclass_entry_t *prev = entry->prev, *next = entry->next;
+
+            if (prev) {
+                prev->next = next;
+            }
+            if (next) {
+                next->prev = prev;
+            }
 
-    if (entry) {
-        rb_subclass_entry_t *prev = entry->prev, *next = entry->next;
+            if (first_entry) {
+                if (next) {
+                    st_update(tbl, box_id, remove_class_from_subclasses_replace_first_entry, (st_data_t)next);
+                }
+                else {
+                    // no subclass entries in this ns after the deletion
+                    st_delete(tbl, &box_id, NULL);
+                }
+            }
 
-        if (prev) {
-            prev->next = next;
+            xfree(entry);
+
+            break;
         }
-        if (next) {
-            next->prev = prev;
+        else if (first_entry) {
+            first_entry = false;
         }
+        entry = entry->next;
+    }
+}
+
+void
+rb_class_remove_from_super_subclasses(VALUE klass)
+{
+    rb_classext_t *ext = RCLASS_EXT_WRITABLE(klass);
+    rb_box_subclasses_t *box_subclasses = RCLASSEXT_BOX_SUPER_SUBCLASSES(ext);
+
+    if (!box_subclasses) return;
+    remove_class_from_subclasses(box_subclasses->tbl, box_subclasses_tbl_key(RCLASSEXT_BOX(ext)), klass);
+    rb_box_subclasses_ref_dec(box_subclasses);
+    RCLASSEXT_BOX_SUPER_SUBCLASSES(ext) = 0;
+}
 
+void
+rb_class_classext_free_subclasses(rb_classext_t *ext, VALUE klass, bool replacing)
+{
+    rb_subclass_anchor_t *anchor = RCLASSEXT_SUBCLASSES(ext);
+    struct st_table *tbl = anchor->box_subclasses->tbl;
+    VALUE box_id = box_subclasses_tbl_key(RCLASSEXT_BOX(ext));
+    rb_subclass_entry_t *next, *entry = anchor->head;
+
+    while (entry) {
+        next = entry->next;
         xfree(entry);
+        entry = next;
     }
+    VM_ASSERT(
+        rb_box_subclasses_ref_count(anchor->box_subclasses) > 0,
+        "box_subclasses refcount (%p) %ld", anchor->box_subclasses, rb_box_subclasses_ref_count(anchor->box_subclasses));
+    st_delete(tbl, &box_id, NULL);
+    rb_box_subclasses_ref_dec(anchor->box_subclasses);
+    xfree(anchor);
 
-    RCLASS_MODULE_SUBCLASS_ENTRY(klass) = NULL;
+    if (RCLASSEXT_BOX_SUPER_SUBCLASSES(ext)) {
+        rb_box_subclasses_t *box_sub = RCLASSEXT_BOX_SUPER_SUBCLASSES(ext);
+        if (!replacing) remove_class_from_subclasses(box_sub->tbl, box_id, klass);
+        rb_box_subclasses_ref_dec(box_sub);
+    }
+    if (RCLASSEXT_BOX_MODULE_SUBCLASSES(ext)) {
+        rb_box_subclasses_t *box_sub = RCLASSEXT_BOX_MODULE_SUBCLASSES(ext);
+        if (!replacing) remove_class_from_subclasses(box_sub->tbl, box_id, klass);
+        rb_box_subclasses_ref_dec(box_sub);
+    }
 }
 
 void
 rb_class_foreach_subclass(VALUE klass, void (*f)(VALUE, VALUE), VALUE arg)
 {
-    // RCLASS_SUBCLASSES should always point to our head element which has NULL klass
-    rb_subclass_entry_t *cur = RCLASS_SUBCLASSES(klass);
-    // if we have a subclasses list, then the head is a placeholder with no valid
-    // class. So ignore it and use the next element in the list (if one exists)
-    if (cur) {
-        RUBY_ASSERT(!cur->klass);
-        cur = cur->next;
-    }
-
+    rb_subclass_entry_t *tmp;
+    rb_subclass_entry_t *cur = RCLASS_SUBCLASSES_FIRST(klass);
     /* do not be tempted to simplify this loop into a for loop, the order of
        operations is important here if `f` modifies the linked list */
     while (cur) {
         VALUE curklass = cur->klass;
-        cur = cur->next;
+        tmp = cur->next;
         // do not trigger GC during f, otherwise the cur will become
         // a dangling pointer if the subclass is collected
         f(curklass, arg);
+        cur = tmp;
     }
 }
 
@@ -162,107 +733,168 @@ class_detach_subclasses(VALUE klass, VALUE arg)
     rb_class_remove_from_super_subclasses(klass);
 }
 
-void
-rb_class_detach_subclasses(VALUE klass)
-{
-    rb_class_foreach_subclass(klass, class_detach_subclasses, Qnil);
-}
-
 static void
-class_detach_module_subclasses(VALUE klass, VALUE arg)
+class_switch_superclass(VALUE super, VALUE klass)
 {
-    rb_class_remove_from_module_subclasses(klass);
-}
-
-void
-rb_class_detach_module_subclasses(VALUE klass)
-{
-    rb_class_foreach_subclass(klass, class_detach_module_subclasses, Qnil);
+    RB_VM_LOCKING() {
+        class_detach_subclasses(klass, Qnil);
+        rb_class_subclass_add(super, klass);
+    }
 }
 
 /**
- * Allocates a struct RClass for a new class.
+ * Allocates a struct RClass for a new class, iclass, or module.
  *
- * \param flags     initial value for basic.flags of the returned class.
- * \param klass     the class of the returned class.
- * \return          an uninitialized Class object.
- * \pre  \p klass must refer \c Class class or an ancestor of Class.
- * \pre  \code (flags | T_CLASS) != 0  \endcode
- * \post the returned class can safely be \c #initialize 'd.
+ * @param type      The type of the RClass (T_CLASS, T_ICLASS, or T_MODULE)
+ * @param klass     value for basic.klass of the returned object.
+ * @return          an uninitialized Class/IClass/Module object.
+ * @pre  `klass` must refer to a class or module
  *
- * \note this function is not Class#allocate.
+ * @note this function is not Class#allocate.
  */
 static VALUE
-class_alloc(VALUE flags, VALUE klass)
+class_alloc0(enum ruby_value_type type, VALUE klass, bool boxable)
 {
-    size_t alloc_size = sizeof(struct RClass);
+    rb_box_subclasses_t *box_subclasses;
+    rb_subclass_anchor_t *anchor;
+    const rb_box_t *box = rb_current_box();
 
-#if USE_RVARGC
-    alloc_size += sizeof(rb_classext_t);
-#endif
+    if (!ruby_box_init_done) {
+        boxable = true;
+    }
+
+    size_t alloc_size = sizeof(struct RClass_and_rb_classext_t);
+    if (boxable) {
+        alloc_size = sizeof(struct RClass_boxable);
+    }
 
-    flags &= T_MASK;
-    flags |= FL_PROMOTED1 /* start from age == 2 */;
+    // class_alloc is supposed to return a new object that is not promoted yet.
+    // So, we need to avoid GC after NEWOBJ_OF.
+    // To achieve that, we allocate subclass lists before NEWOBJ_OF.
+    //
+    // TODO: Note that this could cause memory leak.
+    // If NEWOBJ_OF fails with out of memory, these buffers will leak.
+    box_subclasses = ZALLOC(rb_box_subclasses_t);
+    box_subclasses->refcount = 1;
+    box_subclasses->tbl = st_init_numtable();
+    anchor = ZALLOC(rb_subclass_anchor_t);
+    anchor->box_subclasses = box_subclasses;
+    anchor->head = ZALLOC(rb_subclass_entry_t);
+
+    RUBY_ASSERT(type == T_CLASS || type == T_ICLASS || type == T_MODULE);
+
+    VALUE flags = type | FL_SHAREABLE;
     if (RGENGC_WB_PROTECTED_CLASS) flags |= FL_WB_PROTECTED;
-    RVARGC_NEWOBJ_OF(obj, struct RClass, klass, flags, alloc_size);
+    if (boxable) flags |= RCLASS_BOXABLE;
 
-#if USE_RVARGC
-    memset(RCLASS_EXT(obj), 0, sizeof(rb_classext_t));
-# if SIZEOF_SERIAL_T != SIZEOF_VALUE
-    RCLASS(obj)->class_serial_ptr = ZALLOC(rb_serial_t);
-# endif
-#else
-    obj->ptr = ZALLOC(rb_classext_t);
-#endif
+    NEWOBJ_OF(obj, struct RClass, klass, flags, alloc_size, 0);
+
+    obj->object_id = 0;
+
+    memset(RCLASS_EXT_PRIME(obj), 0, sizeof(rb_classext_t));
 
     /* ZALLOC
-      RCLASS_IV_TBL(obj) = 0;
       RCLASS_CONST_TBL(obj) = 0;
       RCLASS_M_TBL(obj) = 0;
-      RCLASS_IV_INDEX_TBL(obj) = 0;
+      RCLASS_FIELDS(obj) = 0;
       RCLASS_SET_SUPER((VALUE)obj, 0);
-      RCLASS_SUBCLASSES(obj) = NULL;
-      RCLASS_PARENT_SUBCLASSES(obj) = NULL;
-      RCLASS_MODULE_SUBCLASSES(obj) = NULL;
      */
+
+    if (boxable) {
+        ((struct RClass_boxable *)obj)->box_classext_tbl = NULL;
+    }
+
+    RCLASS_PRIME_BOX((VALUE)obj) = box;
+    // Classes/Modules defined in user boxes are
+    // writable directly because it exists only in a box.
+    RCLASS_SET_PRIME_CLASSEXT_WRITABLE((VALUE)obj, !boxable || BOX_USER_P(box));
+
     RCLASS_SET_ORIGIN((VALUE)obj, (VALUE)obj);
-    RCLASS_SERIAL(obj) = rb_next_class_serial();
-    RB_OBJ_WRITE(obj, &RCLASS_REFINED_CLASS(obj), Qnil);
-    RCLASS_ALLOCATOR(obj) = 0;
+    RCLASS_SET_REFINED_CLASS((VALUE)obj, Qnil);
+
+    RCLASS_SET_SUBCLASSES((VALUE)obj, anchor);
 
     return (VALUE)obj;
 }
 
+static VALUE
+class_alloc(enum ruby_value_type type, VALUE klass)
+{
+    bool boxable = rb_box_available() && BOX_ROOT_P(rb_current_box());
+    return class_alloc0(type, klass, boxable);
+}
+
+static VALUE
+class_associate_super(VALUE klass, VALUE super, bool init)
+{
+    if (super && !UNDEF_P(super)) {
+        class_switch_superclass(super, klass);
+    }
+    if (init) {
+        RCLASS_SET_SUPER(klass, super);
+    }
+    else {
+        RCLASS_WRITE_SUPER(klass, super);
+    }
+    rb_class_update_superclasses(klass);
+    return super;
+}
+
+VALUE
+rb_class_set_super(VALUE klass, VALUE super)
+{
+    return class_associate_super(klass, super, false);
+}
+
 static void
-RCLASS_M_TBL_INIT(VALUE c)
+class_initialize_method_table(VALUE c)
 {
-    RCLASS_M_TBL(c) = rb_id_table_create(0);
+    // initialize the prime classext m_tbl
+    RCLASS_SET_M_TBL(c, rb_id_table_create(0));
 }
 
-/*!
+static void
+class_clear_method_table(VALUE c)
+{
+    RCLASS_WRITE_M_TBL(c, rb_id_table_create(0));
+}
+
+static VALUE
+class_boot_boxable(VALUE super, bool boxable)
+{
+    VALUE klass = class_alloc0(T_CLASS, rb_cClass, boxable);
+
+    // initialize method table prior to class_associate_super()
+    // because class_associate_super() may cause GC and promote klass
+    class_initialize_method_table(klass);
+
+    class_associate_super(klass, super, true);
+    if (super && !UNDEF_P(super)) {
+        rb_class_set_initialized(klass);
+    }
+
+    return (VALUE)klass;
+}
+
+/**
  * A utility function that wraps class_alloc.
  *
  * allocates a class and initializes safely.
- * \param super     a class from which the new class derives.
- * \return          a class object.
- * \pre  \a super must be a class.
- * \post the metaclass of the new class is Class.
+ * @param super     a class from which the new class derives.
+ * @return          a class object.
+ * @pre  `super` must be a class.
+ * @post the metaclass of the new class is Class.
  */
 VALUE
 rb_class_boot(VALUE super)
 {
-    VALUE klass = class_alloc(T_CLASS, rb_cClass);
-
-    RCLASS_SET_SUPER(klass, super);
-    RCLASS_M_TBL_INIT(klass);
-
-    return (VALUE)klass;
+    return class_boot_boxable(super, false);
 }
 
 static VALUE *
 class_superclasses_including_self(VALUE klass)
 {
-    if (FL_TEST_RAW(klass, RCLASS_SUPERCLASSES_INCLUDE_SELF))
+    if (RCLASS_SUPERCLASSES_WITH_SELF_P(klass))
         return RCLASS_SUPERCLASSES(klass);
 
     size_t depth = RCLASS_SUPERCLASS_DEPTH(klass);
@@ -271,18 +903,18 @@ class_superclasses_including_self(VALUE klass)
         memcpy(superclasses, RCLASS_SUPERCLASSES(klass), sizeof(VALUE) * depth);
     superclasses[depth] = klass;
 
-    RCLASS_SUPERCLASSES(klass) = superclasses;
-    FL_SET_RAW(klass, RCLASS_SUPERCLASSES_INCLUDE_SELF);
     return superclasses;
 }
 
 void
 rb_class_update_superclasses(VALUE klass)
 {
+    VALUE *superclasses;
+    size_t super_depth;
     VALUE super = RCLASS_SUPER(klass);
 
     if (!RB_TYPE_P(klass, T_CLASS)) return;
-    if (super == Qundef) return;
+    if (UNDEF_P(super)) return;
 
     // If the superclass array is already built
     if (RCLASS_SUPERCLASSES(klass))
@@ -307,8 +939,17 @@ rb_class_update_superclasses(VALUE klass)
             return;
     }
 
-    RCLASS_SUPERCLASSES(klass) = class_superclasses_including_self(super);
-    RCLASS_SUPERCLASS_DEPTH(klass) = RCLASS_SUPERCLASS_DEPTH(super) + 1;
+    super_depth = RCLASS_SUPERCLASS_DEPTH(super);
+    if (RCLASS_SUPERCLASSES_WITH_SELF_P(super)) {
+        superclasses = RCLASS_SUPERCLASSES(super);
+    }
+    else {
+        superclasses = class_superclasses_including_self(super);
+        RCLASS_WRITE_SUPERCLASSES(super, super_depth, superclasses, true);
+    }
+
+    size_t depth = super_depth == RCLASS_MAX_SUPERCLASS_DEPTH ? super_depth : super_depth + 1;
+    RCLASS_WRITE_SUPERCLASSES(klass, depth, superclasses, false);
 }
 
 void
@@ -318,7 +959,7 @@ rb_check_inheritable(VALUE super)
         rb_raise(rb_eTypeError, "superclass must be an instance of Class (given an instance of %"PRIsVALUE")",
                  rb_obj_class(super));
     }
-    if (RBASIC(super)->flags & FL_SINGLETON) {
+    if (RCLASS_SINGLETON_P(super)) {
         rb_raise(rb_eTypeError, "can't make subclass of singleton class");
     }
     if (super == rb_cClass) {
@@ -331,7 +972,15 @@ rb_class_new(VALUE super)
 {
     Check_Type(super, T_CLASS);
     rb_check_inheritable(super);
-    return rb_class_boot(super);
+    VALUE klass = rb_class_boot(super);
+
+    if (super != rb_cObject && super != rb_cBasicObject) {
+        RCLASS_SET_MAX_IV_COUNT(klass, RCLASS_MAX_IV_COUNT(super));
+    }
+
+    RUBY_ASSERT(getenv("RUBY_BOX") || RCLASS_PRIME_CLASSEXT_WRITABLE_P(klass));
+
+    return klass;
 }
 
 VALUE
@@ -344,8 +993,7 @@ static void
 clone_method(VALUE old_klass, VALUE new_klass, ID mid, const rb_method_entry_t *me)
 {
     if (me->def->type == VM_METHOD_TYPE_ISEQ) {
-        rb_cref_t *new_cref;
-        rb_vm_rewrite_cref(me->def->body.iseq.cref, old_klass, new_klass, &new_cref);
+        rb_cref_t *new_cref = rb_vm_rewrite_cref(me->def->body.iseq.cref, old_klass, new_klass);
         rb_add_method_iseq(new_klass, mid, me->def->body.iseq.iseqptr, new_cref, METHOD_ENTRY_VISI(me));
     }
     else {
@@ -395,70 +1043,86 @@ class_init_copy_check(VALUE clone, VALUE orig)
     if (orig == rb_cBasicObject) {
         rb_raise(rb_eTypeError, "can't copy the root class");
     }
-    if (RCLASS_SUPER(clone) != 0 || clone == rb_cBasicObject) {
+    if (RCLASS_INITIALIZED_P(clone)) {
         rb_raise(rb_eTypeError, "already initialized class");
     }
-    if (FL_TEST(orig, FL_SINGLETON)) {
+    if (RCLASS_SINGLETON_P(orig)) {
         rb_raise(rb_eTypeError, "can't copy singleton class");
     }
 }
 
+struct cvc_table_copy_ctx {
+    VALUE clone;
+    struct rb_id_table * new_table;
+};
+
+static enum rb_id_table_iterator_result
+cvc_table_copy(ID id, VALUE val, void *data)
+{
+    struct cvc_table_copy_ctx *ctx = (struct cvc_table_copy_ctx *)data;
+    struct rb_cvar_class_tbl_entry * orig_entry;
+    orig_entry = (struct rb_cvar_class_tbl_entry *)val;
+
+    struct rb_cvar_class_tbl_entry *ent;
+
+    ent = ALLOC(struct rb_cvar_class_tbl_entry);
+    ent->class_value = ctx->clone;
+    ent->cref = orig_entry->cref;
+    ent->global_cvar_state = orig_entry->global_cvar_state;
+    rb_id_table_insert(ctx->new_table, id, (VALUE)ent);
+
+    RB_OBJ_WRITTEN(ctx->clone, Qundef, ent->cref);
+
+    return ID_TABLE_CONTINUE;
+}
+
 static void
 copy_tables(VALUE clone, VALUE orig)
 {
-    if (RCLASS_IV_TBL(clone)) {
-        st_free_table(RCLASS_IV_TBL(clone));
-        RCLASS_IV_TBL(clone) = 0;
-    }
     if (RCLASS_CONST_TBL(clone)) {
         rb_free_const_table(RCLASS_CONST_TBL(clone));
-        RCLASS_CONST_TBL(clone) = 0;
+        RCLASS_WRITE_CONST_TBL(clone, 0, false);
     }
-    RCLASS_M_TBL(clone) = 0;
-    if (RCLASS_IV_TBL(orig)) {
-        st_data_t id;
+    if (RCLASS_CVC_TBL(orig)) {
+        struct rb_id_table *rb_cvc_tbl = RCLASS_CVC_TBL(orig);
+        struct rb_id_table *rb_cvc_tbl_dup = rb_id_table_create(rb_id_table_size(rb_cvc_tbl));
 
-        rb_iv_tbl_copy(clone, orig);
-        CONST_ID(id, "__tmp_classpath__");
-        st_delete(RCLASS_IV_TBL(clone), &id, 0);
-        CONST_ID(id, "__classpath__");
-        st_delete(RCLASS_IV_TBL(clone), &id, 0);
-        CONST_ID(id, "__classid__");
-        st_delete(RCLASS_IV_TBL(clone), &id, 0);
+        struct cvc_table_copy_ctx ctx;
+        ctx.clone = clone;
+        ctx.new_table = rb_cvc_tbl_dup;
+        rb_id_table_foreach(rb_cvc_tbl, cvc_table_copy, &ctx);
+        RCLASS_WRITE_CVC_TBL(clone, rb_cvc_tbl_dup);
+    }
+    rb_id_table_free(RCLASS_M_TBL(clone));
+    RCLASS_WRITE_M_TBL(clone, 0);
+    if (!RB_TYPE_P(clone, T_ICLASS)) {
+        rb_fields_tbl_copy(clone, orig);
     }
     if (RCLASS_CONST_TBL(orig)) {
         struct clone_const_arg arg;
-
-        arg.tbl = RCLASS_CONST_TBL(clone) = rb_id_table_create(0);
+        struct rb_id_table *const_tbl;
+        struct rb_id_table *orig_tbl = RCLASS_CONST_TBL(orig);
+        arg.tbl = const_tbl = rb_id_table_create(rb_id_table_size(orig_tbl));
         arg.klass = clone;
-        rb_id_table_foreach(RCLASS_CONST_TBL(orig), clone_const_i, &arg);
+        rb_id_table_foreach(orig_tbl, clone_const_i, &arg);
+        RCLASS_WRITE_CONST_TBL(clone, const_tbl, false);
     }
 }
 
 static bool ensure_origin(VALUE klass);
 
-/**
- * If this flag is set, that module is allocated but not initialized yet.
- */
-enum {RMODULE_ALLOCATED_BUT_NOT_INITIALIZED = RUBY_FL_USER5};
-
-static inline bool
-RMODULE_UNINITIALIZED(VALUE module)
-{
-    return FL_TEST_RAW(module, RMODULE_ALLOCATED_BUT_NOT_INITIALIZED);
-}
-
 void
-rb_module_set_initialized(VALUE mod)
+rb_class_set_initialized(VALUE klass)
 {
-    FL_UNSET_RAW(mod, RMODULE_ALLOCATED_BUT_NOT_INITIALIZED);
+    RUBY_ASSERT(RB_TYPE_P(klass, T_CLASS) || RB_TYPE_P(klass, T_MODULE));
+    FL_SET_RAW(klass, RCLASS_IS_INITIALIZED);
     /* no more re-initialization */
 }
 
 void
 rb_module_check_initializable(VALUE mod)
 {
-    if (!RMODULE_UNINITIALIZED(mod)) {
+    if (RCLASS_INITIALIZED_P(mod)) {
         rb_raise(rb_eTypeError, "already initialized module");
     }
 }
@@ -467,9 +1131,11 @@ rb_module_check_initializable(VALUE mod)
 VALUE
 rb_mod_init_copy(VALUE clone, VALUE orig)
 {
+    /* Only class or module is valid here, but other classes may enter here and
+     * only hit an exception on the OBJ_INIT_COPY checks
+     */
     switch (BUILTIN_TYPE(clone)) {
       case T_CLASS:
-      case T_ICLASS:
         class_init_copy_check(clone, orig);
         break;
       case T_MODULE:
@@ -480,28 +1146,35 @@ rb_mod_init_copy(VALUE clone, VALUE orig)
     }
     if (!OBJ_INIT_COPY(clone, orig)) return clone;
 
+    RUBY_ASSERT(RB_TYPE_P(orig, T_CLASS) || RB_TYPE_P(orig, T_MODULE));
+    RUBY_ASSERT(BUILTIN_TYPE(clone) == BUILTIN_TYPE(orig));
+
+    rb_class_set_initialized(clone);
+
     /* cloned flag is refer at constant inline cache
      * see vm_get_const_key_cref() in vm_insnhelper.c
      */
-    FL_SET(clone, RCLASS_CLONED);
-    FL_SET(orig , RCLASS_CLONED);
+    RCLASS_SET_CLONED(clone, true);
+    RCLASS_SET_CLONED(orig, true);
 
-    if (!FL_TEST(CLASS_OF(clone), FL_SINGLETON)) {
+    if (!RCLASS_SINGLETON_P(CLASS_OF(clone))) {
         RBASIC_SET_CLASS(clone, rb_singleton_class_clone(orig));
         rb_singleton_class_attached(METACLASS_OF(clone), (VALUE)clone);
     }
-    RCLASS_ALLOCATOR(clone) = RCLASS_ALLOCATOR(orig);
+    if (BUILTIN_TYPE(clone) == T_CLASS) {
+        RCLASS_SET_ALLOCATOR(clone, RCLASS_ALLOCATOR(orig));
+    }
     copy_tables(clone, orig);
     if (RCLASS_M_TBL(orig)) {
         struct clone_method_arg arg;
         arg.old_klass = orig;
         arg.new_klass = clone;
-        RCLASS_M_TBL_INIT(clone);
+        class_initialize_method_table(clone);
         rb_id_table_foreach(RCLASS_M_TBL(orig), clone_method_i, &arg);
     }
 
     if (RCLASS_ORIGIN(orig) == orig) {
-        RCLASS_SET_SUPER(clone, RCLASS_SUPER(orig));
+        rb_class_set_super(clone, RCLASS_SUPER(orig));
     }
     else {
         VALUE p = RCLASS_SUPER(orig);
@@ -521,13 +1194,11 @@ rb_mod_init_copy(VALUE clone, VALUE orig)
             if (BUILTIN_TYPE(p) != T_ICLASS) {
                 rb_bug("non iclass between module/class and origin");
             }
-            clone_p = class_alloc(RBASIC(p)->flags, METACLASS_OF(p));
-            RCLASS_SET_SUPER(prev_clone_p, clone_p);
+            clone_p = class_alloc(T_ICLASS, METACLASS_OF(p));
+            RCLASS_SET_M_TBL(clone_p, RCLASS_M_TBL(p));
+            rb_class_set_super(prev_clone_p, clone_p);
             prev_clone_p = clone_p;
-            RCLASS_M_TBL(clone_p) = RCLASS_M_TBL(p);
-            RCLASS_CONST_TBL(clone_p) = RCLASS_CONST_TBL(p);
-            RCLASS_IV_TBL(clone_p) = RCLASS_IV_TBL(p);
-            RCLASS_ALLOCATOR(clone_p) = RCLASS_ALLOCATOR(p);
+            RCLASS_SET_CONST_TBL(clone_p, RCLASS_CONST_TBL(p), false);
             if (RB_TYPE_P(clone, T_CLASS)) {
                 RCLASS_SET_INCLUDER(clone_p, clone);
             }
@@ -539,8 +1210,8 @@ rb_mod_init_copy(VALUE clone, VALUE orig)
             }
             else if ((origin_len = RARRAY_LEN(origin_stack)) > 1 &&
                      RARRAY_AREF(origin_stack, origin_len - 1) == p) {
-                RCLASS_SET_ORIGIN(RARRAY_AREF(origin_stack, (origin_len -= 2)), clone_p);
-                RICLASS_SET_ORIGIN_SHARED_MTBL(clone_p);
+                RCLASS_WRITE_ORIGIN(RARRAY_AREF(origin_stack, (origin_len -= 2)), clone_p);
+                RICLASS_WRITE_ORIGIN_SHARED_MTBL(clone_p);
                 rb_ary_resize(origin_stack, origin_len);
                 add_subclass = FALSE;
             }
@@ -552,15 +1223,15 @@ rb_mod_init_copy(VALUE clone, VALUE orig)
 
         if (p == orig_origin) {
             if (clone_p) {
-                RCLASS_SET_SUPER(clone_p, clone_origin);
-                RCLASS_SET_SUPER(clone_origin, RCLASS_SUPER(orig_origin));
+                rb_class_set_super(clone_p, clone_origin);
+                rb_class_set_super(clone_origin, RCLASS_SUPER(orig_origin));
             }
             copy_tables(clone_origin, orig_origin);
             if (RCLASS_M_TBL(orig_origin)) {
                 struct clone_method_arg arg;
                 arg.old_klass = orig;
                 arg.new_klass = clone;
-                RCLASS_M_TBL_INIT(clone_origin);
+                class_initialize_method_table(clone_origin);
                 rb_id_table_foreach(RCLASS_M_TBL(orig_origin), clone_method_i, &arg);
             }
         }
@@ -590,14 +1261,15 @@ rb_singleton_class_clone_and_attach(VALUE obj, VALUE attach)
     // attached to an object other than `obj`. In which case `obj` does not have
     // a material singleton class attached yet and there is no singleton class
     // to clone.
-    if (!(FL_TEST(klass, FL_SINGLETON) && rb_attr_get(klass, id_attached) == obj)) {
+    if (!(RCLASS_SINGLETON_P(klass) && RCLASS_ATTACHED_OBJECT(klass) == obj)) {
         // nothing to clone
         return klass;
     }
     else {
         /* copy singleton(unnamed) class */
         bool klass_of_clone_is_new;
-        VALUE clone = class_alloc(RBASIC(klass)->flags, 0);
+        RUBY_ASSERT(RB_TYPE_P(klass, T_CLASS));
+        VALUE clone = class_alloc(T_CLASS, 0);
 
         if (BUILTIN_TYPE(obj) == T_CLASS) {
             klass_of_clone_is_new = true;
@@ -611,21 +1283,22 @@ rb_singleton_class_clone_and_attach(VALUE obj, VALUE attach)
             RBASIC_SET_CLASS(clone, klass_metaclass_clone);
         }
 
-        RCLASS_SET_SUPER(clone, RCLASS_SUPER(klass));
-        RCLASS_ALLOCATOR(clone) = RCLASS_ALLOCATOR(klass);
-        if (RCLASS_IV_TBL(klass)) {
-            rb_iv_tbl_copy(clone, klass);
-        }
+        // initialize method table before any GC chance
+        class_initialize_method_table(clone);
+
+        rb_class_set_super(clone, RCLASS_SUPER(klass));
+        rb_fields_tbl_copy(clone, klass);
         if (RCLASS_CONST_TBL(klass)) {
             struct clone_const_arg arg;
-            arg.tbl = RCLASS_CONST_TBL(clone) = rb_id_table_create(0);
+            struct rb_id_table *table;
+            arg.tbl = table = rb_id_table_create(rb_id_table_size(RCLASS_CONST_TBL(klass)));
             arg.klass = clone;
             rb_id_table_foreach(RCLASS_CONST_TBL(klass), clone_const_i, &arg);
+            RCLASS_SET_CONST_TBL(clone, table, false);
         }
-        if (attach != Qundef) {
+        if (!UNDEF_P(attach)) {
             rb_singleton_class_attached(clone, attach);
         }
-        RCLASS_M_TBL_INIT(clone);
         {
             struct clone_method_arg arg;
             arg.old_klass = klass;
@@ -644,8 +1317,8 @@ rb_singleton_class_clone_and_attach(VALUE obj, VALUE attach)
 void
 rb_singleton_class_attached(VALUE klass, VALUE obj)
 {
-    if (FL_TEST(klass, FL_SINGLETON)) {
-        rb_class_ivar_set(klass, id_attached, obj);
+    if (RCLASS_SINGLETON_P(klass)) {
+        RCLASS_SET_ATTACHED_OBJECT(klass, obj);
     }
 }
 
@@ -659,17 +1332,17 @@ rb_singleton_class_attached(VALUE klass, VALUE obj)
 static int
 rb_singleton_class_has_metaclass_p(VALUE sklass)
 {
-    return rb_attr_get(METACLASS_OF(sklass), id_attached) == sklass;
+    return RCLASS_ATTACHED_OBJECT(METACLASS_OF(sklass)) == sklass;
 }
 
 int
 rb_singleton_class_internal_p(VALUE sklass)
 {
-    return (RB_TYPE_P(rb_attr_get(sklass, id_attached), T_CLASS) &&
+    return (RB_TYPE_P(RCLASS_ATTACHED_OBJECT(sklass), T_CLASS) &&
             !rb_singleton_class_has_metaclass_p(sklass));
 }
 
-/*!
+/**
  * whether k has a metaclass
  * @retval 1 if \a k has a metaclass
  * @retval 0 otherwise
@@ -678,31 +1351,31 @@ rb_singleton_class_internal_p(VALUE sklass)
     (FL_TEST(METACLASS_OF(k), FL_SINGLETON) && \
      rb_singleton_class_has_metaclass_p(k))
 
-/*!
- * ensures \a klass belongs to its own eigenclass.
- * @return the eigenclass of \a klass
- * @post \a klass belongs to the returned eigenclass.
- *       i.e. the attached object of the eigenclass is \a klass.
+/**
+ * ensures `klass` belongs to its own eigenclass.
+ * @return the eigenclass of `klass`
+ * @post `klass` belongs to the returned eigenclass.
+ *       i.e. the attached object of the eigenclass is `klass`.
  * @note this macro creates a new eigenclass if necessary.
  */
 #define ENSURE_EIGENCLASS(klass) \
     (HAVE_METACLASS_P(klass) ? METACLASS_OF(klass) : make_metaclass(klass))
 
 
-/*!
- * Creates a metaclass of \a klass
- * \param klass     a class
- * \return          created metaclass for the class
- * \pre \a klass is a Class object
- * \pre \a klass has no singleton class.
- * \post the class of \a klass is the returned class.
- * \post the returned class is meta^(n+1)-class when \a klass is a meta^(n)-klass for n >= 0
+/**
+ * Creates a metaclass of `klass`
+ * @param klass     a class
+ * @return          created metaclass for the class
+ * @pre `klass` is a Class object
+ * @pre `klass` has no singleton class.
+ * @post the class of `klass` is the returned class.
+ * @post the returned class is meta^(n+1)-class when `klass` is a meta^(n)-klass for n >= 0
  */
 static inline VALUE
 make_metaclass(VALUE klass)
 {
     VALUE super;
-    VALUE metaclass = rb_class_boot(Qundef);
+    VALUE metaclass = class_boot_boxable(Qundef, FL_TEST_RAW(klass, RCLASS_BOXABLE));
 
     FL_SET(metaclass, FL_SINGLETON);
     rb_singleton_class_attached(metaclass, klass);
@@ -719,7 +1392,8 @@ make_metaclass(VALUE klass)
 
     super = RCLASS_SUPER(klass);
     while (RB_TYPE_P(super, T_ICLASS)) super = RCLASS_SUPER(super);
-    RCLASS_SET_SUPER(metaclass, super ? ENSURE_EIGENCLASS(super) : rb_cClass);
+    class_associate_super(metaclass, super ? ENSURE_EIGENCLASS(super) : rb_cClass, true);
+    rb_class_set_initialized(klass);
 
     // Full class ancestry may not have been filled until we reach here.
     rb_class_update_superclasses(METACLASS_OF(metaclass));
@@ -727,21 +1401,23 @@ make_metaclass(VALUE klass)
     return metaclass;
 }
 
-/*!
- * Creates a singleton class for \a obj.
- * \pre \a obj must not a immediate nor a special const.
- * \pre \a obj must not a Class object.
- * \pre \a obj has no singleton class.
+/**
+ * Creates a singleton class for `obj`.
+ * @pre `obj` must not be an immediate nor a special const.
+ * @pre `obj` must not be a Class object.
+ * @pre `obj` has no singleton class.
  */
 static inline VALUE
 make_singleton_class(VALUE obj)
 {
     VALUE orig_class = METACLASS_OF(obj);
-    VALUE klass = rb_class_boot(orig_class);
+    VALUE klass = class_boot_boxable(orig_class, FL_TEST_RAW(orig_class, RCLASS_BOXABLE));
 
     FL_SET(klass, FL_SINGLETON);
     RBASIC_SET_CLASS(obj, klass);
     rb_singleton_class_attached(klass, obj);
+    rb_yjit_invalidate_no_singleton_class(orig_class);
+    rb_zjit_invalidate_no_singleton_class(orig_class);
 
     SET_METACLASS_OF(klass, METACLASS_OF(rb_class_real(orig_class)));
     return klass;
@@ -755,7 +1431,7 @@ boot_defclass(const char *name, VALUE super)
     ID id = rb_intern(name);
 
     rb_const_set((rb_cObject ? rb_cObject : obj), id, obj);
-    rb_vm_add_root_module(obj);
+    rb_vm_register_global_object(obj);
     return obj;
 }
 
@@ -811,12 +1487,33 @@ refinement_import_methods(int argc, VALUE *argv, VALUE refinement)
 }
 # endif
 
+/*!
+ *--
+ * \private
+ * Initializes the world of objects and classes.
+ *
+ * At first, the function bootstraps the class hierarchy.
+ * It initializes the most fundamental classes and their metaclasses.
+ * - \c BasicObject
+ * - \c Object
+ * - \c Module
+ * - \c Class
+ * After the bootstrap step, the class hierarchy becomes as the following
+ * diagram.
+ *
+ * \image html boottime-classes.png
+ *
+ * Then, the function defines classes, modules and methods as usual.
+ * \ingroup class
+ *++
+ */
+
 void
 Init_class_hierarchy(void)
 {
     rb_cBasicObject = boot_defclass("BasicObject", 0);
     rb_cObject = boot_defclass("Object", rb_cBasicObject);
-    rb_gc_register_mark_object(rb_cObject);
+    rb_vm_register_global_object(rb_cObject);
 
     /* resolve class name ASAP for order-independence */
     rb_set_class_path_string(rb_cObject, rb_cObject, rb_fstring_lit("Object"));
@@ -841,15 +1538,15 @@ Init_class_hierarchy(void)
 }
 
 
-/*!
- * \internal
+/**
+ * @internal
  * Creates a new *singleton class* for an object.
  *
- * \pre \a obj has no singleton class.
- * \note DO NOT USE the function in an extension libraries. Use \ref rb_singleton_class.
- * \param obj     An object.
- * \param unused  ignored.
- * \return        The singleton class of the object.
+ * @pre `obj` has no singleton class.
+ * @note DO NOT USE the function in an extension libraries. Use @ref rb_singleton_class.
+ * @param obj     An object.
+ * @param unused  ignored.
+ * @return        The singleton class of the object.
  */
 VALUE
 rb_make_metaclass(VALUE obj, VALUE unused)
@@ -875,15 +1572,15 @@ rb_define_class_id(ID id, VALUE super)
 }
 
 
-/*!
+/**
  * Calls Class#inherited.
- * \param super  A class which will be called #inherited.
+ * @param super  A class which will be called #inherited.
  *               NULL means Object class.
- * \param klass  A Class object which derived from \a super
- * \return the value \c Class#inherited's returns
- * \pre Each of \a super and \a klass must be a \c Class object.
+ * @param klass  A Class object which derived from `super`
+ * @return the value `Class#inherited` returns
+ * @pre Each of `super` and `klass` must be a `Class` object.
  */
-MJIT_FUNC_EXPORTED VALUE
+VALUE
 rb_class_inherited(VALUE super, VALUE klass)
 {
     ID inherited;
@@ -896,9 +1593,8 @@ VALUE
 rb_define_class(const char *name, VALUE super)
 {
     VALUE klass;
-    ID id;
+    ID id = rb_intern(name);
 
-    id = rb_intern(name);
     if (rb_const_defined(rb_cObject, id)) {
         klass = rb_const_get(rb_cObject, id);
         if (!RB_TYPE_P(klass, T_CLASS)) {
@@ -910,14 +1606,14 @@ rb_define_class(const char *name, VALUE super)
         }
 
         /* Class may have been defined in Ruby and not pin-rooted */
-        rb_vm_add_root_module(klass);
+        rb_vm_register_global_object(klass);
         return klass;
     }
     if (!super) {
-        rb_raise(rb_eArgError, "no super class for `%s'", name);
+        rb_raise(rb_eArgError, "no super class for '%s'", name);
     }
     klass = rb_define_class_id(id, super);
-    rb_vm_add_root_module(klass);
+    rb_vm_register_global_object(klass);
     rb_const_set(rb_cObject, id, klass);
     rb_class_inherited(super, klass);
 
@@ -931,7 +1627,7 @@ rb_define_class_under(VALUE outer, const char *name, VALUE super)
 }
 
 VALUE
-rb_define_class_id_under(VALUE outer, ID id, VALUE super)
+rb_define_class_id_under_no_pin(VALUE outer, ID id, VALUE super)
 {
     VALUE klass;
 
@@ -948,30 +1644,34 @@ rb_define_class_id_under(VALUE outer, ID id, VALUE super)
                      " (%"PRIsVALUE" is given but was %"PRIsVALUE")",
                      outer, rb_id2str(id), RCLASS_SUPER(klass), super);
         }
-        /* Class may have been defined in Ruby and not pin-rooted */
-        rb_vm_add_root_module(klass);
 
         return klass;
     }
     if (!super) {
-        rb_raise(rb_eArgError, "no super class for `%"PRIsVALUE"::%"PRIsVALUE"'",
+        rb_raise(rb_eArgError, "no super class for '%"PRIsVALUE"::%"PRIsVALUE"'",
                  rb_class_path(outer), rb_id2str(id));
     }
     klass = rb_define_class_id(id, super);
     rb_set_class_path_string(klass, outer, rb_id2str(id));
     rb_const_set(outer, id, klass);
     rb_class_inherited(super, klass);
-    rb_vm_add_root_module(klass);
 
     return klass;
 }
 
 VALUE
+rb_define_class_id_under(VALUE outer, ID id, VALUE super)
+{
+    VALUE klass = rb_define_class_id_under_no_pin(outer, id, super);
+    rb_vm_register_global_object(klass);
+    return klass;
+}
+
+VALUE
 rb_module_s_alloc(VALUE klass)
 {
     VALUE mod = class_alloc(T_MODULE, klass);
-    RCLASS_M_TBL_INIT(mod);
-    FL_SET(mod, RMODULE_ALLOCATED_BUT_NOT_INITIALIZED);
+    class_initialize_method_table(mod);
     return mod;
 }
 
@@ -979,7 +1679,7 @@ static inline VALUE
 module_new(VALUE klass)
 {
     VALUE mdl = class_alloc(T_MODULE, klass);
-    RCLASS_M_TBL_INIT(mdl);
+    class_initialize_method_table(mdl);
     return (VALUE)mdl;
 }
 
@@ -1006,9 +1706,8 @@ VALUE
 rb_define_module(const char *name)
 {
     VALUE module;
-    ID id;
+    ID id = rb_intern(name);
 
-    id = rb_intern(name);
     if (rb_const_defined(rb_cObject, id)) {
         module = rb_const_get(rb_cObject, id);
         if (!RB_TYPE_P(module, T_MODULE)) {
@@ -1016,11 +1715,11 @@ rb_define_module(const char *name)
                      name, rb_obj_class(module));
         }
         /* Module may have been defined in Ruby and not pin-rooted */
-        rb_vm_add_root_module(module);
+        rb_vm_register_global_object(module);
         return module;
     }
     module = rb_module_new();
-    rb_vm_add_root_module(module);
+    rb_vm_register_global_object(module);
     rb_const_set(rb_cObject, id, module);
 
     return module;
@@ -1045,13 +1744,13 @@ rb_define_module_id_under(VALUE outer, ID id)
                      outer, rb_id2str(id), rb_obj_class(module));
         }
         /* Module may have been defined in Ruby and not pin-rooted */
-        rb_gc_register_mark_object(module);
+        rb_vm_register_global_object(module);
         return module;
     }
     module = rb_module_new();
     rb_const_set(outer, id, module);
     rb_set_class_path_string(module, outer, rb_id2str(id));
-    rb_gc_register_mark_object(module);
+    rb_vm_register_global_object(module);
 
     return module;
 }
@@ -1061,24 +1760,24 @@ rb_include_class_new(VALUE module, VALUE super)
 {
     VALUE klass = class_alloc(T_ICLASS, rb_cClass);
 
-    RCLASS_M_TBL(klass) = RCLASS_M_TBL(module);
+    RCLASS_SET_M_TBL(klass, RCLASS_WRITABLE_M_TBL(module));
 
     RCLASS_SET_ORIGIN(klass, klass);
     if (BUILTIN_TYPE(module) == T_ICLASS) {
         module = METACLASS_OF(module);
     }
     RUBY_ASSERT(!RB_TYPE_P(module, T_ICLASS));
-    if (!RCLASS_IV_TBL(module)) {
-        RCLASS_IV_TBL(module) = st_init_numtable();
+    if (RCLASS_WRITABLE_CONST_TBL(module)) {
+        RCLASS_SET_CONST_TBL(klass, RCLASS_WRITABLE_CONST_TBL(module), true);
     }
-    if (!RCLASS_CONST_TBL(module)) {
-        RCLASS_CONST_TBL(module) = rb_id_table_create(0);
+    else {
+        RCLASS_WRITE_CONST_TBL(module, rb_id_table_create(0), false);
+        RCLASS_SET_CONST_TBL(klass, RCLASS_WRITABLE_CONST_TBL(module), true);
     }
-    RCLASS_IV_TBL(klass) = RCLASS_IV_TBL(module);
-    RCLASS_CVC_TBL(klass) = RCLASS_CVC_TBL(module);
-    RCLASS_CONST_TBL(klass) = RCLASS_CONST_TBL(module);
 
-    RCLASS_SET_SUPER(klass, super);
+    RCLASS_SET_CVC_TBL(klass, RCLASS_WRITABLE_CVC_TBL(module));
+
+    class_associate_super(klass, super, true);
     RBASIC_SET_CLASS(klass, module);
 
     return (VALUE)klass;
@@ -1091,7 +1790,7 @@ ensure_includable(VALUE klass, VALUE module)
 {
     rb_class_modify_check(klass);
     Check_Type(module, T_MODULE);
-    rb_module_set_initialized(module);
+    rb_class_set_initialized(module);
     if (!NIL_P(rb_refinement_module_get_refined_class(module))) {
         rb_raise(rb_eArgError, "refinement module is not allowed");
     }
@@ -1109,15 +1808,9 @@ rb_include_module(VALUE klass, VALUE module)
         rb_raise(rb_eArgError, "cyclic include detected");
 
     if (RB_TYPE_P(klass, T_MODULE)) {
-        rb_subclass_entry_t *iclass = RCLASS_SUBCLASSES(klass);
-        // skip the placeholder subclass entry at the head of the list
-        if (iclass) {
-            RUBY_ASSERT(!iclass->klass);
-            iclass = iclass->next;
-        }
-
-        int do_include = 1;
+        rb_subclass_entry_t *iclass = RCLASS_SUBCLASSES_FIRST(klass);
         while (iclass) {
+            int do_include = 1;
             VALUE check_class = iclass->klass;
             /* During lazy sweeping, iclass->klass could be a dead object that
              * has not yet been swept. */
@@ -1184,7 +1877,7 @@ static int
 do_include_modules_at(const VALUE klass, VALUE c, VALUE module, int search_super, bool check_cyclic)
 {
     VALUE p, iclass, origin_stack = 0;
-    int method_changed = 0, add_subclass;
+    int method_changed = 0;
     long origin_len;
     VALUE klass_origin = RCLASS_ORIGIN(klass);
     VALUE original_klass = klass;
@@ -1246,9 +1939,8 @@ do_include_modules_at(const VALUE klass, VALUE c, VALUE module, int search_super
 
         // setup T_ICLASS for the include/prepend module
         iclass = rb_include_class_new(module, super_class);
-        c = RCLASS_SET_SUPER(c, iclass);
+        c = rb_class_set_super(c, iclass);
         RCLASS_SET_INCLUDER(iclass, klass);
-        add_subclass = TRUE;
         if (module != RCLASS_ORIGIN(module)) {
             if (!origin_stack) origin_stack = rb_ary_hidden_new(2);
             VALUE origin[2] = {iclass, RCLASS_ORIGIN(module)};
@@ -1256,17 +1948,14 @@ do_include_modules_at(const VALUE klass, VALUE c, VALUE module, int search_super
         }
         else if (origin_stack && (origin_len = RARRAY_LEN(origin_stack)) > 1 &&
                  RARRAY_AREF(origin_stack, origin_len - 1) == module) {
-            RCLASS_SET_ORIGIN(RARRAY_AREF(origin_stack, (origin_len -= 2)), iclass);
-            RICLASS_SET_ORIGIN_SHARED_MTBL(iclass);
+            RCLASS_WRITE_ORIGIN(RARRAY_AREF(origin_stack, (origin_len -= 2)), iclass);
+            RICLASS_WRITE_ORIGIN_SHARED_MTBL(iclass);
             rb_ary_resize(origin_stack, origin_len);
-            add_subclass = FALSE;
         }
 
-        if (add_subclass) {
-            VALUE m = module;
-            if (BUILTIN_TYPE(m) == T_ICLASS) m = METACLASS_OF(m);
-            rb_module_add_to_subclasses_list(m, iclass);
-        }
+        VALUE m = module;
+        if (BUILTIN_TYPE(m) == T_ICLASS) m = METACLASS_OF(m);
+        rb_module_add_to_subclasses_list(m, iclass);
 
         if (BUILTIN_TYPE(klass) == T_MODULE && FL_TEST(klass, RMODULE_IS_REFINEMENT)) {
             VALUE refined_class =
@@ -1299,7 +1988,7 @@ move_refined_method(ID key, VALUE value, void *data)
 
     if (me->def->type == VM_METHOD_TYPE_REFINED) {
         VALUE klass = (VALUE)data;
-        struct rb_id_table *tbl = RCLASS_M_TBL(klass);
+        struct rb_id_table *tbl = RCLASS_WRITABLE_M_TBL(klass);
 
         if (me->def->body.refined.orig_me) {
             const rb_method_entry_t *orig_me = me->def->body.refined.orig_me, *new_me;
@@ -1340,11 +2029,16 @@ ensure_origin(VALUE klass)
     VALUE origin = RCLASS_ORIGIN(klass);
     if (origin == klass) {
         origin = class_alloc(T_ICLASS, klass);
-        RCLASS_SET_SUPER(origin, RCLASS_SUPER(klass));
-        RCLASS_SET_SUPER(klass, origin);
-        RCLASS_SET_ORIGIN(klass, origin);
-        RCLASS_M_TBL(origin) = RCLASS_M_TBL(klass);
-        RCLASS_M_TBL_INIT(klass);
+        RCLASS_SET_M_TBL(origin, RCLASS_M_TBL(klass));
+        rb_class_set_super(origin, RCLASS_SUPER(klass));
+        rb_class_set_super(klass, origin); // writes origin into RCLASS_SUPER(klass)
+        RCLASS_WRITE_ORIGIN(klass, origin);
+
+        // RCLASS_WRITE_ORIGIN marks origin as an origin, so this is the first
+        // point that it sees M_TBL and may mark it
+        rb_gc_writebarrier_remember(origin);
+
+        class_clear_method_table(klass);
         rb_id_table_foreach(RCLASS_M_TBL(origin), cache_clear_refined_method, (void *)klass);
         rb_id_table_foreach(RCLASS_M_TBL(origin), move_refined_method, (void *)klass);
         return true;
@@ -1369,13 +2063,7 @@ rb_prepend_module(VALUE klass, VALUE module)
         rb_vm_check_redefinition_by_prepend(klass);
     }
     if (RB_TYPE_P(klass, T_MODULE)) {
-        rb_subclass_entry_t *iclass = RCLASS_SUBCLASSES(klass);
-        // skip the placeholder subclass entry at the head of the list if it exists
-        if (iclass) {
-            RUBY_ASSERT(!iclass->klass);
-            iclass = iclass->next;
-        }
-
+        rb_subclass_entry_t *iclass = RCLASS_SUBCLASSES_FIRST(klass);
         VALUE klass_origin = RCLASS_ORIGIN(klass);
         struct rb_id_table *klass_m_tbl = RCLASS_M_TBL(klass);
         struct rb_id_table *klass_origin_m_tbl = RCLASS_M_TBL(klass_origin);
@@ -1387,11 +2075,11 @@ rb_prepend_module(VALUE klass, VALUE module)
                 if (klass_had_no_origin && klass_origin_m_tbl == RCLASS_M_TBL(subclass)) {
                     // backfill an origin iclass to handle refinements and future prepends
                     rb_id_table_foreach(RCLASS_M_TBL(subclass), clear_module_cache_i, (void *)subclass);
-                    RCLASS_M_TBL(subclass) = klass_m_tbl;
+                    RCLASS_WRITE_M_TBL(subclass, klass_m_tbl);
                     VALUE origin = rb_include_class_new(klass_origin, RCLASS_SUPER(subclass));
-                    RCLASS_SET_SUPER(subclass, origin);
+                    rb_class_set_super(subclass, origin);
                     RCLASS_SET_INCLUDER(origin, RCLASS_INCLUDER(subclass));
-                    RCLASS_SET_ORIGIN(subclass, origin);
+                    RCLASS_WRITE_ORIGIN(subclass, origin);
                     RICLASS_SET_ORIGIN_SHARED_MTBL(origin);
                 }
                 include_modules_at(subclass, subclass, module, FALSE);
@@ -1467,7 +2155,7 @@ rb_mod_include_p(VALUE mod, VALUE mod2)
 
     Check_Type(mod2, T_MODULE);
     for (p = RCLASS_SUPER(mod); p; p = RCLASS_SUPER(p)) {
-        if (BUILTIN_TYPE(p) == T_ICLASS && !FL_TEST(p, RICLASS_IS_ORIGIN)) {
+        if (BUILTIN_TYPE(p) == T_ICLASS && !RICLASS_IS_ORIGIN_P(p)) {
             if (METACLASS_OF(p) == mod2) return Qtrue;
         }
     }
@@ -1527,7 +2215,7 @@ class_descendants_recursive(VALUE klass, VALUE v)
 {
     struct subclass_traverse_data *data = (struct subclass_traverse_data *) v;
 
-    if (BUILTIN_TYPE(klass) == T_CLASS && !FL_TEST(klass, FL_SINGLETON)) {
+    if (BUILTIN_TYPE(klass) == T_CLASS && !RCLASS_SINGLETON_P(klass)) {
         if (data->buffer && data->count < data->maxcount && !rb_objspace_garbage_object_p(klass)) {
             // assumes that this does not cause GC as long as the length does not exceed the capacity
             rb_ary_push(data->buffer, klass);
@@ -1583,6 +2271,27 @@ class_descendants(VALUE klass, bool immediate_only)
  *     A.subclasses        #=> [D, B]
  *     B.subclasses        #=> [C]
  *     C.subclasses        #=> []
+ *
+ *  Anonymous subclasses (not associated with a constant) are
+ *  returned, too:
+ *
+ *     c = Class.new(A)
+ *     A.subclasses        # => [#<Class:0x00007f003c77bd78>, D, B]
+ *
+ *  Note that the parent does not hold references to subclasses
+ *  and doesn't prevent them from being garbage collected. This
+ *  means that the subclass might disappear when all references
+ *  to it are dropped:
+ *
+ *     # drop the reference to subclass, it can be garbage-collected now
+ *     c = nil
+ *
+ *     A.subclasses
+ *     # It can be
+ *     #  => [#<Class:0x00007f003c77bd78>, D, B]
+ *     # ...or just
+ *     #  => [D, B]
+ *     # ...depending on whether garbage collector was run
  */
 
 VALUE
@@ -1591,6 +2300,33 @@ rb_class_subclasses(VALUE klass)
     return class_descendants(klass, true);
 }
 
+/*
+ *  call-seq:
+ *     attached_object -> object
+ *
+ *  Returns the object for which the receiver is the singleton class.
+ *
+ *  Raises an TypeError if the class is not a singleton class.
+ *
+ *     class Foo; end
+ *
+ *     Foo.singleton_class.attached_object        #=> Foo
+ *     Foo.attached_object                        #=> TypeError: `Foo' is not a singleton class
+ *     Foo.new.singleton_class.attached_object    #=> #<Foo:0x000000010491a370>
+ *     TrueClass.attached_object                  #=> TypeError: `TrueClass' is not a singleton class
+ *     NilClass.attached_object                   #=> TypeError: `NilClass' is not a singleton class
+ */
+
+VALUE
+rb_class_attached_object(VALUE klass)
+{
+    if (!RCLASS_SINGLETON_P(klass)) {
+        rb_raise(rb_eTypeError, "'%"PRIsVALUE"' is not a singleton class", klass);
+    }
+
+    return RCLASS_ATTACHED_OBJECT(klass);
+}
+
 static void
 ins_methods_push(st_data_t name, st_data_t ary)
 {
@@ -1641,10 +2377,7 @@ ins_methods_pub_i(st_data_t name, st_data_t type, st_data_t ary)
 static int
 ins_methods_undef_i(st_data_t name, st_data_t type, st_data_t ary)
 {
-    if ((rb_method_visibility_t)type == METHOD_VISI_UNDEF) {
-        ins_methods_push(name, ary);
-    }
-    return ST_CONTINUE;
+    return ins_methods_type_i(name, type, ary, METHOD_VISI_UNDEF);
 }
 
 struct method_entry_arg {
@@ -1690,7 +2423,7 @@ static bool
 particular_class_p(VALUE mod)
 {
     if (!mod) return false;
-    if (FL_TEST(mod, FL_SINGLETON)) return true;
+    if (RCLASS_SINGLETON_P(mod)) return true;
     if (BUILTIN_TYPE(mod) == T_ICLASS) return true;
     return false;
 }
@@ -1967,19 +2700,19 @@ rb_obj_singleton_methods(int argc, const VALUE *argv, VALUE obj)
     int recur = TRUE;
 
     if (rb_check_arity(argc, 0, 1)) recur = RTEST(argv[0]);
-    if (RB_TYPE_P(obj, T_CLASS) && FL_TEST(obj, FL_SINGLETON)) {
+    if (RCLASS_SINGLETON_P(obj)) {
         rb_singleton_class(obj);
     }
     klass = CLASS_OF(obj);
     origin = RCLASS_ORIGIN(klass);
     me_arg.list = st_init_numtable();
     me_arg.recur = recur;
-    if (klass && FL_TEST(klass, FL_SINGLETON)) {
+    if (klass && RCLASS_SINGLETON_P(klass)) {
         if ((mtbl = RCLASS_M_TBL(origin)) != 0) rb_id_table_foreach(mtbl, method_entry_i, &me_arg);
         klass = RCLASS_SUPER(klass);
     }
     if (recur) {
-        while (klass && (FL_TEST(klass, FL_SINGLETON) || RB_TYPE_P(klass, T_ICLASS))) {
+        while (klass && (RCLASS_SINGLETON_P(klass) || RB_TYPE_P(klass, T_ICLASS))) {
             if (klass != origin && (mtbl = RCLASS_M_TBL(klass)) != 0) rb_id_table_foreach(mtbl, method_entry_i, &me_arg);
             klass = RCLASS_SUPER(klass);
         }
@@ -2083,17 +2816,17 @@ rb_special_singleton_class(VALUE obj)
     return special_singleton_class_of(obj);
 }
 
-/*!
- * \internal
- * Returns the singleton class of \a obj. Creates it if necessary.
+/**
+ * @internal
+ * Returns the singleton class of `obj`. Creates it if necessary.
  *
- * \note DO NOT expose the returned singleton class to
+ * @note DO NOT expose the returned singleton class to
  *       outside of class.c.
- *       Use \ref rb_singleton_class instead for
+ *       Use @ref rb_singleton_class instead for
  *       consistency of the metaclass hierarchy.
  */
 static VALUE
-singleton_class_of(VALUE obj)
+singleton_class_of(VALUE obj, bool ensure_eigenclass)
 {
     VALUE klass;
 
@@ -2113,20 +2846,34 @@ singleton_class_of(VALUE obj)
         return klass;
 
       case T_STRING:
-        if (FL_TEST_RAW(obj, RSTRING_FSTR)) {
+        if (CHILLED_STRING_P(obj)) {
+            CHILLED_STRING_MUTATED(obj);
+        }
+        else if (FL_TEST_RAW(obj, RSTRING_FSTR)) {
             rb_raise(rb_eTypeError, "can't define singleton");
         }
     }
 
-    klass = METACLASS_OF(obj);
-    if (!(FL_TEST(klass, FL_SINGLETON) &&
-          rb_attr_get(klass, id_attached) == obj)) {
-        rb_serial_t serial = RCLASS_SERIAL(klass);
-        klass = rb_make_metaclass(obj, klass);
-        RCLASS_SERIAL(klass) = serial;
+    bool needs_lock = rb_multi_ractor_p() && rb_ractor_shareable_p(obj);
+    unsigned int lev;
+    if (needs_lock) {
+        RB_VM_LOCK_ENTER_LEV(&lev);
+    }
+    {
+        klass = METACLASS_OF(obj);
+        if (!(RCLASS_SINGLETON_P(klass) &&
+            RCLASS_ATTACHED_OBJECT(klass) == obj)) {
+            klass = rb_make_metaclass(obj, klass);
+        }
+        RB_FL_SET_RAW(klass, RB_OBJ_FROZEN_RAW(obj));
+        if (ensure_eigenclass && RB_TYPE_P(obj, T_CLASS)) {
+            /* ensures an exposed class belongs to its own eigenclass */
+            (void)ENSURE_EIGENCLASS(klass);
+        }
+    }
+    if (needs_lock) {
+        RB_VM_LOCK_LEAVE_LEV(&lev);
     }
-
-    RB_FL_SET_RAW(klass, RB_OBJ_FROZEN_RAW(obj));
 
     return klass;
 }
@@ -2135,21 +2882,22 @@ void
 rb_freeze_singleton_class(VALUE x)
 {
     /* should not propagate to meta-meta-class, and so on */
-    if (!(RBASIC(x)->flags & FL_SINGLETON)) {
+    if (!RCLASS_SINGLETON_P(x)) {
         VALUE klass = RBASIC_CLASS(x);
-        if (klass && (klass = RCLASS_ORIGIN(klass)) != 0 &&
-            FL_TEST(klass, (FL_SINGLETON|FL_FREEZE)) == FL_SINGLETON) {
-            OBJ_FREEZE_RAW(klass);
+        if (klass && // no class when hidden from ObjectSpace
+            FL_TEST_RAW(klass, FL_SINGLETON) &&
+            !OBJ_FROZEN_RAW(klass)) {
+            OBJ_FREEZE(klass);
         }
     }
 }
 
-/*!
- * Returns the singleton class of \a obj, or nil if obj is not a
+/**
+ * Returns the singleton class of `obj`, or nil if obj is not a
  * singleton object.
  *
- * \param obj an arbitrary object.
- * \return the singleton class or nil.
+ * @param obj an arbitrary object.
+ * @return the singleton class or nil.
  */
 VALUE
 rb_singleton_class_get(VALUE obj)
@@ -2160,20 +2908,15 @@ rb_singleton_class_get(VALUE obj)
         return rb_special_singleton_class(obj);
     }
     klass = METACLASS_OF(obj);
-    if (!FL_TEST(klass, FL_SINGLETON)) return Qnil;
-    if (rb_attr_get(klass, id_attached) != obj) return Qnil;
+    if (!RCLASS_SINGLETON_P(klass)) return Qnil;
+    if (RCLASS_ATTACHED_OBJECT(klass) != obj) return Qnil;
     return klass;
 }
 
 VALUE
 rb_singleton_class(VALUE obj)
 {
-    VALUE klass = singleton_class_of(obj);
-
-    /* ensures an exposed class belongs to its own eigenclass */
-    if (RB_TYPE_P(obj, T_CLASS)) (void)ENSURE_EIGENCLASS(klass);
-
-    return klass;
+    return singleton_class_of(obj, true);
 }
 
 /*!
@@ -2191,7 +2934,7 @@ rb_singleton_class(VALUE obj)
 void
 rb_define_singleton_method(VALUE obj, const char *name, VALUE (*func)(ANYARGS), int argc)
 {
-    rb_define_method(singleton_class_of(obj), name, func, argc);
+    rb_define_method(singleton_class_of(obj, false), name, func, argc);
 }
 
 #ifdef rb_define_module_function
@@ -2225,7 +2968,7 @@ rb_define_attr(VALUE klass, const char *name, int read, int write)
     rb_attr(klass, rb_intern(name), read, write, FALSE);
 }
 
-MJIT_FUNC_EXPORTED VALUE
+VALUE
 rb_keyword_error_new(const char *error, VALUE keys)
 {
     long i = 0, len = RARRAY_LEN(keys);
diff --git a/common.mk b/common.mk
index bef00d191f..8891b65ed9 100644
--- a/common.mk
+++ b/common.mk