0 files changed, 0 insertions, 0 deletions
diff --git a/.appveyor.yml b/.appveyor.yml
new file mode 100644
index 0000000000..05ff204541
--- /dev/null
+++ b/.appveyor.yml
@@ -0,0 +1,134 @@
+---
+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'
+    - '**/*.[1-8]'
+    - '**/*.ronn'
+environment:
+  ruby_version: "24-%Platform%"
+  matrix:
+    # Test only the oldest supported version because AppVeyor is unstable, its concurrency
+    # is limited, and compatibility issues that happen only in newer versions are rare.
+    # You may test some other stuff on GitHub Actions instead.
+    - build: vs
+      vs: 120 # Visual Studio 2013
+      ssl: OpenSSL-v111
+      # The worker image name. This is NOT the Visual Studio version we're using here.
+      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
+    - ps: Start-FileDownload 'https://github.com/microsoft/vcpkg-tool/releases/download/2023-08-09/vcpkg.exe' -FileName 'C:\Tools\vcpkg\vcpkg.exe'
+    - cd %APPVEYOR_BUILD_FOLDER%
+    - vcpkg --triplet %Platform%-windows install --x-use-aria2 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
+    - 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:
+    - set HAVE_GIT=no
+    - 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=--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=--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",
+          "url": "{{buildUrl}}",
+          "commit": "{{commitId}}",
+          "branch": "{{branch}}"
+        }
+      {{/isPullRequest}}
+    on_build_success: false
+    on_build_failure: true
+    on_build_status_changed: false
diff --git a/.document b/.document
index 0e0969a6d3..3a6b0c238c 100644
--- a/.document
+++ b/.document
@@ -10,16 +10,26 @@
 # prelude
 prelude.rb
 rbconfig.rb
+
 array.rb
 ast.rb
 dir.rb
 gc.rb
-integer.rb
 io.rb
 kernel.rb
+marshal.rb
+mjit.rb
+numeric.rb
+nilclass.rb
 pack.rb
+ractor.rb
+string.rb
+symbol.rb
+timev.rb
+thread_sync.rb
 trace_point.rb
 warning.rb
+yjit.rb
 
 # the lib/ directory (which has its own .document file)
 lib
@@ -35,7 +45,6 @@ README.ja.md
 
 COPYING
 COPYING.ja
-CONTRIBUTING.md
 
 LEGAL
 
diff --git a/.gdbinit b/.gdbinit
index 714d7bee10..34d044caf6 100644
--- a/.gdbinit
+++ b/.gdbinit
@@ -265,6 +265,10 @@ define rp
     printf "%sT_ZOMBIE%s: ", $color_type, $color_end
     print (struct RData *)($arg0)
   else
+  if ($flags & RUBY_T_MASK) == RUBY_T_MOVED
+    printf "%sT_MOVED%s: ", $color_type, $color_end
+    print *(struct RMoved *)$arg0
+  else
     printf "%sunknown%s: ", $color_type, $color_end
     print (struct RBasic *)($arg0)
   end
@@ -300,6 +304,7 @@ define rp
   end
   end
   end
+  end
 end
 document rp
   Print a Ruby's VALUE.
@@ -539,13 +544,13 @@ end
 
 define rp_class
   printf "(struct RClass *) %p", (void*)$arg0
-  if ((struct RClass *)($arg0))->ptr.origin_ != $arg0
-    printf " -> %p", ((struct RClass *)($arg0))->ptr.origin_
+  if RCLASS_ORIGIN((struct RClass *)($arg0)) != $arg0
+    printf " -> %p", RCLASS_ORIGIN((struct RClass *)($arg0))
   end
   printf "\n"
   rb_classname $arg0
   print/x *(struct RClass *)($arg0)
-  print *((struct RClass *)($arg0))->ptr
+  print *RCLASS_EXT((struct RClass *)($arg0))
 end
 document rp_class
   Print the content of a Class/Module.
@@ -974,8 +979,8 @@ end
 
 define rb_ps_vm
   print $ps_vm = (rb_vm_t*)$arg0
-  set $ps_thread_ln = $ps_vm->living_threads.n.next
-  set $ps_thread_ln_last = $ps_vm->living_threads.n.prev
+  set $ps_thread_ln      = $ps_vm->ractor.main_ractor.threads.set.n.next
+  set $ps_thread_ln_last = $ps_vm->ractor.main_ractor.threads.set.n.prev
   while 1
     set $ps_thread_th = (rb_thread_t *)$ps_thread_ln
     set $ps_thread = (VALUE)($ps_thread_th->self)
@@ -1097,11 +1102,11 @@ define print_id
           set $arylen = $ary->as.heap.len
         end
         set $result = $aryptr[($serial % ID_ENTRY_UNIT) * ID_ENTRY_SIZE + $t]
-	if $result != RUBY_Qnil
+        if $result != RUBY_Qnil
           print_string $result
-	else
-	  echo undef
-	end
+        else
+          echo undef
+        end
       end
     end
   end
@@ -1319,8 +1324,7 @@ define print_flags
   printf "RUBY_FL_PROMOTED0   : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_PROMOTED0 ? "1" : "0"
   printf "RUBY_FL_PROMOTED1   : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_PROMOTED1 ? "1" : "0"
   printf "RUBY_FL_FINALIZE    : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_FINALIZE ? "1" : "0"
-  printf "RUBY_FL_TAINT       : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_TAINT ? "1" : "0"
-  printf "RUBY_FL_UNTRUSTED   : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_UNTRUSTED ? "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"
   printf "RUBY_FL_FREEZE      : %s\n", ((struct RBasic*)($arg0))->flags & RUBY_FL_FREEZE ? "1" : "0"
 
diff --git a/.git-blame-ignore-revs b/.git-blame-ignore-revs
new file mode 100644
index 0000000000..6c5eac5a0f
--- /dev/null
+++ b/.git-blame-ignore-revs
@@ -0,0 +1,23 @@
+# This is a file used by GitHub to ignore the following commits on `git blame`.
+#
+# You can also do the same thing in your local repository with:
+# $ git config --local blame.ignoreRevsFile .git-blame-ignore-revs
+
+# Expand tabs
+5b21e94bebed90180d8ff63dad03b8b948361089
+
+# Enable Style/StringLiterals cop for RubyGems/Bundler
+d7ffd3fea402239b16833cc434404a7af82d44f3
+
+# [ruby/digest] Revert tab-expansion in external files
+48b09aae7ec5632209229dcc294dd0d75a93a17f
+8a65cf3b61c60e4cb886f59a73ff6db44364bfa9
+39dc9f9093901d40d2998653948d5da38b18ee2c
+
+# [ruby/io-nonblock] Revert tab expansion
+f28287d34c03f472ffe90ea262bdde9affd4b965
+0d842fecb4f75ab3b1d4097ebdb8e88f51558041
+4ba2c66761d6a293abdfba409241d31063cefd62
+
+# Make benchmark indentation consistent
+fc4acf8cae82e5196186d3278d831f2438479d91
diff --git a/.github/codeql/codeql-config.yml b/.github/codeql/codeql-config.yml
index 7196708b21..91f82b842b 100644
--- a/.github/codeql/codeql-config.yml
+++ b/.github/codeql/codeql-config.yml
@@ -1,4 +1,3 @@
 name: "CodeQL config for the Ruby language"
 
-paths-ignore:
-  - '/ext/**/*/conftest.c'
+languages: cpp
diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000000..bc63aca35b
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: 'github-actions'
+    directory: '/'
+    schedule:
+      interval: 'monthly'
diff --git a/.github/workflows/baseruby.yml b/.github/workflows/baseruby.yml
new file mode 100644
index 0000000000..ebaafe3bf0
--- /dev/null
+++ b/.github/workflows/baseruby.yml
@@ -0,0 +1,80 @@
+name: BASERUBY Check
+
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.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') }}
+
+permissions:
+  contents: read
+
+jobs:
+  baseruby:
+    name: BASERUBY
+    runs-on: ubuntu-22.04
+    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+    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
+
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: .downloaded-cache
+          key: downloaded-cache
+      - uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler: none
+      - run: echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
+      - run: sudo apt-get install build-essential autoconf bison libyaml-dev
+      - run: ./autogen.sh
+      - run: ./configure --disable-install-doc
+      - run: make common-srcs
+      - run: make incs
+      - run: make all
+      - run: make test
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
+        with:
+          payload: |
+            {
+              "ci": "GitHub Actions",
+              "env": "${{ github.workflow }} / BASERUBY @ ${{ matrix.ruby }}",
+              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              "commit": "${{ github.sha }}",
+              "branch": "${{ github.ref_name }}"
+            }
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() && github.event_name == 'push' }}
diff --git a/.github/workflows/bundled_gems.yml b/.github/workflows/bundled_gems.yml
new file mode 100644
index 0000000000..070c0fa1dd
--- /dev/null
+++ b/.github/workflows/bundled_gems.yml
@@ -0,0 +1,166 @@
+name: bundled_gems
+
+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:
+    branches: [ "master" ]
+    paths:
+      - '.github/workflows/bundled_gems.yml'
+      - 'gems/bundled_gems'
+  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 ${{ github.workflow }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: git config
+        run: |
+          git config --global advice.detachedHead 0
+          git config --global init.defaultBranch garbage
+
+      - name: Set ENV
+        run: |
+          echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
+          echo "TODAY=$(date +%F)" >> $GITHUB_ENV
+
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: .downloaded-cache
+          key: downloaded-cache-${{ 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
+
+      - name: Update bundled gems list
+        run: |
+          ruby -i~ tool/update-bundled_gems.rb gems/bundled_gems
+
+      - name: Maintain updated gems list in NEWS
+        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} *#{$2}"
+              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} *#{$2}"
+              added.map {|g, v|"#{mark}#{g} #{v}\n"}.join("")
+            end or next unless added.empty?
+            File.write("NEWS.md", news)
+          end
+        shell: ruby {0}
+
+      - 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
+
+      - 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
+        if: ${{ steps.diff.outcome == 'failure' }}
+
+      - name: Build
+        run: |
+          ./autogen.sh
+          ./configure -C --disable-install-doc
+          make
+        if: ${{ steps.diff.outcome == 'failure' }}
+
+      - name: Prepare bundled gems
+        run: |
+          make -s prepare-gems
+        if: ${{ steps.diff.outcome == 'failure' }}
+
+      - 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
+
+      - name: Commit
+        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: ${{ github.repository == 'ruby/ruby' && !startsWith(github.event_name, 'pull') && steps.show.outcome == 'failure' }}
+
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
+        with:
+          payload: |
+            {
+              "ci": "GitHub Actions",
+              "env": "${{ github.workflow }} / update",
+              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              "commit": "${{ github.sha }}",
+              "branch": "${{ github.ref_name }}"
+            }
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() && github.event_name == 'push' }}
diff --git a/.github/workflows/check_branch.yml b/.github/workflows/check_branch.yml
deleted file mode 100644
index 37cf3a9a8f..0000000000
--- a/.github/workflows/check_branch.yml
+++ /dev/null
@@ -1,22 +0,0 @@
-# We bidirectionally synchronize github.com/ruby/ruby.git's master branch and
-# git.ruby-lang.org/ruby.git's master branch.
-# We can use a pull request's merge button only on the master branch.
-#
-# Therefore, we require to pass this "check_branch" on all protected branches
-# to prevent us from accidentally pushing commits to GitHub directly.
-#
-# Details: https://bugs.ruby-lang.org/issues/16094
-name: Pull Request
-on: [pull_request]
-jobs:
-  check_branch:
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check if branch is master
-        run: |
-          if [ "$BASE_REF" != master ]; then
-            echo "Only master branch accepts a pull request, but it's '$BASE_REF'."
-            exit 1
-          fi
-        env:
-          BASE_REF: ${{ github.base_ref }}
diff --git a/.github/workflows/check_dependencies.yml b/.github/workflows/check_dependencies.yml
new file mode 100644
index 0000000000..79b2916feb
--- /dev/null
+++ b/.github/workflows/check_dependencies.yml
@@ -0,0 +1,78 @@
+name: Check Dependencies
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.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') }}
+
+permissions:
+  contents: read
+
+jobs:
+  update-deps:
+    strategy:
+      matrix:
+        os: [ubuntu-22.04]
+      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
+        if: ${{ contains(matrix.os, 'ubuntu') }}
+      - name: Install libraries
+        run: |
+          brew install gmp libffi openssl@1.1 zlib autoconf automake libtool readline
+        if: ${{ contains(matrix.os, 'macos') }}
+      - name: git config
+        run: |
+          git config --global advice.detachedHead 0
+          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: .downloaded-cache
+          key: downloaded-cache
+      - run: ./autogen.sh
+      - name: Run configure
+        run: ./configure -C --disable-install-doc --disable-rubygems --with-gcc 'optflags=-O0' 'debugflags=-save-temps=obj -g'
+      - run: make all golf
+      - run: ruby tool/update-deps --fix
+      - run: git diff --no-ext-diff --ignore-submodules --exit-code
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
+        with:
+          payload: |
+            {
+              "ci": "GitHub Actions",
+              "env": "${{ matrix.os }} / Dependencies need to update",
+              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              "commit": "${{ github.sha }}",
+              "branch": "${{ github.ref_name }}"
+            }
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() && github.event_name == 'push' }}
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index bee79cb1ab..8dba76fbe2 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -1,40 +1,75 @@
 name: "Code scanning - action"
 
 on:
-  push:
-  pull_request:
+  # push:
+  #   paths-ignore:
+  #     - 'doc/**'
+  #     - '**/man'
+  #     - '**.md'
+  #     - '**.rdoc'
+  #     - '**/.document'
+  # pull_request:
+  #   paths-ignore:
+  #     - 'doc/**'
+  #     - '**/man'
+  #     - '**.md'
+  #     - '**.rdoc'
+  #     - '**/.document'
   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') }}
+
+permissions:  # added using https://github.com/step-security/secure-workflows
+  contents: read
 
 jobs:
   CodeQL-Build:
 
     # CodeQL runs on ubuntu-latest and windows-latest
+    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
     runs-on: ubuntu-latest
+    # CodeQL fails to run pull requests from dependabot due to missing write access to upload results.
+    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') && github.event.head_commit.pusher.name != 'dependabot[bot]' }}
+
+    env:
+      enable_install_doc: no
 
     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 libgdbm-dev bison autoconf ruby
+        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@v2
+      uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+    - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
       with:
-        fetch-depth: 2
+        path: .downloaded-cache
+        key: downloaded-cache
 
-    - run: git checkout HEAD^2
-      if: ${{ github.event_name == 'pull_request' }}
+    - 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@v1
+      uses: github/codeql-action/init@959cbb7472c4d4ad70cdfe6f4976053fe48ab394 # v2.1.37
       with:
-        languages: cpp
         config-file: ./.github/codeql/codeql-config.yml
+        trap-caching: false
+
+    - name: Set ENV
+      run: echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
 
     - name: Autobuild
-      uses: github/codeql-action/autobuild@v1
+      uses: github/codeql-action/autobuild@959cbb7472c4d4ad70cdfe6f4976053fe48ab394 # v2.1.37
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v1
+      uses: github/codeql-action/analyze@959cbb7472c4d4ad70cdfe6f4976053fe48ab394 # v2.1.37
diff --git a/.github/workflows/compilers.yml b/.github/workflows/compilers.yml
index 5e58de225f..caf12cc0f4 100644
--- a/.github/workflows/compilers.yml
+++ b/.github/workflows/compilers.yml
@@ -1,19 +1,42 @@
 name: Compilations
 
-on: [push, pull_request]
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.rdoc'
+      - '**/.document'
 
-# Github actions does not support YAML anchors.  This creative use of
-# environment variables (plus the "echo ::set-env" hack) is to reroute that
+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-11
+  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 runs on a relatively modern CPU
+  # 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 -march=x86-64 -mtune=generic'
+  optflags: '-O1'
 
   # -g0 disables backtraces when SEGV.  Do not set that.
   debugflags: '-ggdb3'
@@ -40,154 +63,206 @@ env:
     --color=always
     --tty=no
 
+permissions:
+  contents: read
+
 jobs:
   compile:
     strategy:
       fail-fast: false
       matrix:
+        env:
+          - {}
         entry:
-          - { key: default_cc, name: gcc-10,    value: gcc-10 }
-          - { key: default_cc, name: gcc-9,     value: gcc-9 }
-          - { key: default_cc, name: gcc-8,     value: gcc-8 }
-          - { key: default_cc, name: gcc-7,     value: gcc-7 }
-          - { key: default_cc, name: gcc-6,     value: gcc-6 }
-          - { key: default_cc, name: gcc-5,     value: gcc-5 }
-          - { key: default_cc, name: gcc-4.8,   value: gcc-4.8 }
-          - { key: default_cc, name: clang-11,  value: clang-11 }
-          - { key: default_cc, name: clang-10,  value: clang-10 }
-          - { key: default_cc, name: clang-9,   value: clang-9 }
-          - { key: default_cc, name: clang-8,   value: clang-8 }
-          - { key: default_cc, name: clang-7,   value: clang-7 }
-          - { key: default_cc, name: clang-6.0, value: clang-6.0 }
-          - { key: default_cc, name: clang-5.0, value: clang-5.0 }
-          - { key: default_cc, name: clang-4.0, value: clang-4.0 }
-          - { key: default_cc, name: clang-3.9, value: clang-3.9 }
-
-          - { key: append_cc, name: c99,   value: '-std=c99   -Werror=pedantic -pedantic-errors' }
-          - { key: append_cc, name: c11,   value: '-std=c11   -Werror=pedantic -pedantic-errors' }
-          - { key: append_cc, name: c17,   value: '-std=c17   -Werror=pedantic -pedantic-errors' }
-          - { key: append_cc, name: c2x,   value: '-std=c2x   -Werror=pedantic -pedantic-errors' }
-          - { key: CXXFLAGS,  name: c++98, value: '-std=c++98 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }
-          - { key: CXXFLAGS,  name: c++11, value: '-std=c++11 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }
-          - { key: CXXFLAGS,  name: c++14, value: '-std=c++14 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }
-          - { key: CXXFLAGS,  name: c++17, value: '-std=c++17 -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }
-          - { key: CXXFLAGS,  name: c++2a, value: '-std=c++2a -Werror=pedantic -pedantic-errors -Wno-c++11-long-long' }
-
-          - { key: optflags, name: '-O0', value: '-O0 -march=x86-64 -mtune=generic' }
-          - { key: optflags, name: '-O3', value: '-O3 -march=x86-64 -mtune=generic' }
-
-          - { key: append_configure, name: gmp,                  value: '--with-gmp' }
-          - { key: append_configure, name: jemalloc,             value: '--with-jemalloc' }
-          - { key: append_configure, name: valgrind,             value: '--with-valgrind' }
-          - { key: append_configure, name: 'coroutine=ucontext', value: '--with-coroutine=ucontext' }
-          - { key: append_configure, name: 'coroutine=copy',     value: '--with-coroutine=copy' }
-          - { key: append_configure, name: disable-mathn,        value: '--disable-mathn' }
-          - { key: append_configure, name: disable-jit-support,  value: '--disable-jit-support' }
-          - { key: append_configure, name: disable-dln,          value: '--disable-dln' }
-          - { key: append_configure, name: disable-rubygems,     value: '--disable-rubygems' }
-
-          - { key: cppflags, name: OPT_THREADED_CODE=1,            value: '-DOPT_THREADED_CODE=1' }
-          - { key: cppflags, name: OPT_THREADED_CODE=2,            value: '-DOPT_THREADED_CODE=2' }
-          - { key: cppflags, name: OPT_THREADED_CODE=3,            value: '-DOPT_THREADED_CODE=3' }
-
-          - { key: cppflags, name: NDEBUG,                         value: '-DNDEBUG' }
-          - { key: cppflags, name: RUBY_DEBUG,                     value: '-DRUBY_DEBUG' }
-          - { key: cppflags, name: ARRAY_DEBUG,                    value: '-DARRAY_DEBUG' }
-          - { key: cppflags, name: BIGNUM_DEBUG,                   value: '-DBIGNUM_DEBUG' }
-          - { key: cppflags, name: CCAN_LIST_DEBUG,                value: '-DCCAN_LIST_DEBUG' }
-          - { key: cppflags, name: CPDEBUG=-1,                     value: '-DCPDEBUG=-1' }
-          - { key: cppflags, name: ENC_DEBUG,                      value: '-DENC_DEBUG' }
-          - { key: cppflags, name: GC_DEBUG,                       value: '-DGC_DEBUG' }
-          - { key: cppflags, name: HASH_DEBUG,                     value: '-DHASH_DEBUG' }
-          - { key: cppflags, name: ID_TABLE_DEBUG,                 value: '-DID_TABLE_DEBUG' }
-          - { key: cppflags, name: RGENGC_DEBUG=-1,                value: '-DRGENGC_DEBUG=-1' }
-          - { key: cppflags, name: SYMBOL_DEBUG,                   value: '-DSYMBOL_DEBUG' }
-          - { key: cppflags, name: THREAD_DEBUG=-1,                value: '-DTHREAD_DEBUG=-1' }
-
-          - { key: cppflags, name: RGENGC_CHECK_MODE,              value: '-DRGENGC_CHECK_MODE' }
-          - { key: cppflags, name: TRANSIENT_HEAP_CHECK_MODE,      value: '-DTRANSIENT_HEAP_CHECK_MODE' }
-          - { key: cppflags, name: VM_CHECK_MODE,                  value: '-DVM_CHECK_MODE' }
-
-          - { key: cppflags, name: USE_EMBED_CI=0,                 value: '-DUSE_EMBED_CI=0' }
-          - { key: cppflags, name: USE_FLONUM=0,                   value: '-DUSE_FLONUM=0' }
-#         - { key: cppflags, name: USE_GC_MALLOC_OBJ_INFO_DETAILS, value: '-DUSE_GC_MALLOC_OBJ_INFO_DETAILS' }
-          - { key: cppflags, name: USE_LAZY_LOAD,                  value: '-DUSE_LAZY_LOAD' }
-          - { key: cppflags, name: USE_RINCGC=0,                   value: '-DUSE_RINCGC=0' }
-          - { key: cppflags, name: USE_SYMBOL_GC=0,                value: '-DUSE_SYMBOL_GC=0' }
-          - { key: cppflags, name: USE_THREAD_CACHE=0,             value: '-DUSE_THREAD_CACHE=0' }
-          - { key: cppflags, name: USE_TRANSIENT_HEAP=0,           value: '-DUSE_TRANSIENT_HEAP=0' }
-          - { key: cppflags, name: USE_RUBY_DEBUG_LOG=1,           value: '-DUSE_RUBY_DEBUG_LOG=1' }
-
-          - { key: cppflags, name: DEBUG_FIND_TIME_NUMGESS,        value: '-DDEBUG_FIND_TIME_NUMGESS' }
-          - { key: cppflags, name: DEBUG_INTEGER_PACK,             value: '-DDEBUG_INTEGER_PACK' }
-          - { key: cppflags, name: ENABLE_PATH_CHECK,              value: '-DENABLE_PATH_CHECK' }
-
-          - { key: cppflags, name: GC_DEBUG_STRESS_TO_CLASS,       value: '-DGC_DEBUG_STRESS_TO_CLASS' }
-          - { key: cppflags, name: GC_ENABLE_LAZY_SWEEP=0,         value: '-DGC_ENABLE_LAZY_SWEEP=0' }
-          - { key: cppflags, name: GC_PROFILE_DETAIL_MEMOTY,       value: '-DGC_PROFILE_DETAIL_MEMOTY' }
-          - { key: cppflags, name: GC_PROFILE_MORE_DETAIL,         value: '-DGC_PROFILE_MORE_DETAIL' }
-
-          - { key: cppflags, name: CALC_EXACT_MALLOC_SIZE,         value: '-DCALC_EXACT_MALLOC_SIZE' }
-          - { key: cppflags, name: MALLOC_ALLOCATED_SIZE_CHECK,    value: '-DMALLOC_ALLOCATED_SIZE_CHECK' }
-
-          - { key: cppflags, name: IBF_ISEQ_ENABLE_LOCAL_BUFFER,   value: '-DIBF_ISEQ_ENABLE_LOCAL_BUFFER' }
-
-          - { key: cppflags, name: RGENGC_ESTIMATE_OLDMALLOC,      value: '-DRGENGC_ESTIMATE_OLDMALLOC' }
-          - { key: cppflags, name: RGENGC_FORCE_MAJOR_GC,          value: '-DRGENGC_FORCE_MAJOR_GC' }
-          - { key: cppflags, name: RGENGC_OBJ_INFO,                value: '-DRGENGC_OBJ_INFO' }
-          - { key: cppflags, name: RGENGC_OLD_NEWOBJ_CHECK,        value: '-DRGENGC_OLD_NEWOBJ_CHECK' }
-          - { key: cppflags, name: RGENGC_PROFILE,                 value: '-DRGENGC_PROFILE' }
-
-          - { key: cppflags, name: VM_DEBUG_BP_CHECK,              value: '-DVM_DEBUG_BP_CHECK' }
-          - { key: cppflags, name: VM_DEBUG_VERIFY_METHOD_CACHE,   value: '-DVM_DEBUG_VERIFY_METHOD_CACHE' }
-
-          - { key: cppflags, name: MJIT_FORCE_ENABLE,              value: '-DMJIT_FORCE_ENABLE' }
+          - { 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-13 LTO'
+            container: gcc-13
+            env:
+              default_cc: 'gcc-13 -flto=auto -ffat-lto-objects -Werror=lto-type-mismatch'
+              optflags: '-O2'
+            shared: disable
+            # 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 } }
+          # llvm-objcopy<=9 doesn't have --wildcard. It compiles, but leaves Rust symbols in libyjit.o.
+          - { name: clang-9,   env: { default_cc: clang-9,   append_configure: '--disable-yjit' } }
+          - { name: clang-8,   env: { default_cc: clang-8,   append_configure: '--disable-yjit' } }
+          - { name: clang-7,   env: { default_cc: clang-7,   append_configure: '--disable-yjit' } }
+          - { name: clang-6.0, env: { default_cc: clang-6.0, append_configure: '--disable-yjit' } }
+          - name: 'clang-16 LTO'
+            container: clang-16
+            env:
+              default_cc: 'clang-16 -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' } }
+
+          - { 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' } }
+
+          - { 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' } }
+
+#         - { 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' } }
+
+          - { name: USE_EMBED_CI=0,                 env: { cppflags: '-DUSE_EMBED_CI=0' } }
+          - name: USE_FLONUM=0,
+            env:
+              cppflags: '-DUSE_FLONUM=0'
+              # yjit requires FLONUM for the pointer tagging scheme
+              append_configure: '--disable-yjit'
+#         - { 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' } }
+
+          - { 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' } }
+
+          - { 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' } }
+
+#         - { name: CALC_EXACT_MALLOC_SIZE,         env: { cppflags: '-DCALC_EXACT_MALLOC_SIZE' } }
+#         - { name: MALLOC_ALLOCATED_SIZE_CHECK,    env: { cppflags: '-DMALLOC_ALLOCATED_SIZE_CHECK' } }
+
+#         - { name: IBF_ISEQ_ENABLE_LOCAL_BUFFER,   env: { cppflags: '-DIBF_ISEQ_ENABLE_LOCAL_BUFFER' } }
+
+#         - { 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' } }
+
+#         - { name: VM_DEBUG_BP_CHECK,              env: { cppflags: '-DVM_DEBUG_BP_CHECK' } }
+#         - { name: VM_DEBUG_VERIFY_METHOD_CACHE,   env: { cppflags: '-DVM_DEBUG_VERIFY_METHOD_CACHE' } }
+
+          - { name: MJIT_FORCE_ENABLE,              env: { cppflags: '-DMJIT_FORCE_ENABLE' } }
+          - { name: YJIT_FORCE_ENABLE,              env: { cppflags: '-DYJIT_FORCE_ENABLE' } }
 
     name: ${{ matrix.entry.name }}
     runs-on: ubuntu-latest
-    container: shyouhei/c-compilers:latest
-    if: "!contains(github.event.head_commit.message, '[ci skip]')"
+    container:
+      image: ghcr.io/ruby/ruby-ci-image:${{ 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: ${{ matrix.entry.env || matrix.env }}
     steps:
+      - run: id
+        working-directory:
+      - run: mkdir build
+        working-directory:
       - name: setenv
         run: |
-          echo ::set-env name=${{ matrix.entry.key }}::${{ matrix.entry.value }}
-          echo ::set-env name=make::make -sj$((1 + $(nproc --all)))
-      - run: mkdir build
-      - uses: actions/checkout@v2
+          echo "GNUMAKEFLAGS=-sj$((1 + $(nproc --all)))" >> $GITHUB_ENV
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - run: autoconf
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: src/.downloaded-cache
+          key: downloaded-cache
+      - run: ./autogen.sh
         working-directory: src
       - name: Run configure
-        working-directory: build
-        run: |
-          ../src/configure -C \
-            ${default_configure} \
-            ${append_configure} \
-            --with-gcc="${default_cc} ${append_cc}"
-      - run: $make incs
-        working-directory: build
-      - run: $make
-        working-directory: build
-      - run: $make test
-        working-directory: build
-      - run: $make install
-        working-directory: build
-        if: "matrix.entry.name == '-O3'"
-      - run: /usr/local/bin/gem install --no-doc timezone tzinfo
-        working-directory: build
-        if: "matrix.entry.name == '-O3'"
-      - run: $make test-tool
-        working-directory: build
-        if: "matrix.entry.name == '-O3'"
-      - run: $make test-all TESTS='-- ruby -ext-'
-        working-directory: build
-        if: "matrix.entry.name == '-O3'"
-      - run: $make test-spec
-        working-directory: build
-        if: "matrix.entry.name == '-O3'"
-
-      - uses: k0kubun/action-slack@v2.0.0
+        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: ${{ matrix.entry.check && endsWith(matrix.entry.name, 'annocheck') }}
+
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
@@ -195,8 +270,12 @@ jobs:
               "env": "${{ github.workflow }} / ${{ matrix.entry.name }}",
               "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
               "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
+              "branch": "${{ github.ref_name }}"
             }
         env:
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: failure() && github.event_name == 'push'
+        if: ${{ failure() && github.event_name == 'push' }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index afd0c88aa4..d8dc58b119 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -1,66 +1,113 @@
 name: macOS
-on: [push, pull_request]
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.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') }}
+
+permissions:
+  contents: read
+
 jobs:
   make:
-    runs-on: macos-latest
     strategy:
       matrix:
-        test_task: [ "check", "test-bundler-parallel", "test-bundled-gems", "leaked-globals" ]
+        test_task: ["check"] # "test-bundler-parallel", "test-bundled-gems"
+        os:
+          - macos-13
+          - macos-14
+          - macos-15
       fail-fast: false
     env:
       GITPULLOPTIONS: --no-tags origin ${{github.ref}}
-    if: "!contains(github.event.head_commit.message, '[ci skip]')"
+    runs-on: ${{ matrix.os }}
+    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
     steps:
-      - name: Disable Firewall
-        run: |
-          sudo /usr/libexec/ApplicationFirewall/socketfilterfw --setglobalstate off
-          sudo /usr/libexec/ApplicationFirewall/socketfilterfw --getglobalstate
+      - run: mkdir build
+        working-directory:
       - name: git config
         run: |
           git config --global advice.detachedHead 0
-      - uses: actions/checkout@v2
+          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - run: ./src/tool/actions-commit-info.sh
-        id: commit_info
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: src/.downloaded-cache
+          key: downloaded-cache
       - name: Install libraries
         run: |
-          export WAITS='5 60'
-          tool/travis_retry.sh brew upgrade
-          tool/travis_retry.sh brew install gdbm gmp libffi openssl@1.1 zlib autoconf automake libtool readline
+          brew install gmp libffi openssl@1.1 zlib autoconf automake libtool readline bison
         working-directory: src
       - name: Set ENV
         run: |
-          echo '::set-env name=JOBS::'-j$((1 + $(sysctl -n hw.activecpu)))
-      - run: autoconf
+          echo "MAKEFLAGS=-j$((1 + $(sysctl -n hw.activecpu)))" >> $GITHUB_ENV
+          echo "PATH="/usr/local/opt/bison/bin:/opt/homebrew/opt/bison/bin:$PATH"" >> $GITHUB_ENV
+      - run: ./autogen.sh
         working-directory: src
-      - run: mkdir build
       - name: Run configure
         run: ../src/configure -C --disable-install-doc --with-openssl-dir=$(brew --prefix openssl@1.1) --with-readline-dir=$(brew --prefix readline)
-        working-directory: build
-      - run: make $JOBS incs
-        working-directory: build
-      - run: make $JOBS
-        working-directory: build
+      - run: make incs
       - run: make prepare-gems
-        working-directory: build
-        if: matrix.test_task == 'check'
-      - run: make $JOBS -s ${{ matrix.test_task }}
-        working-directory: build
+        if: ${{ matrix.test_task == 'test-bundled-gems' }}
+      - run: make
+      - run: make leaked-globals
+        if: ${{ matrix.test_task == 'check' }}
+      - 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
         env:
           RUBY_TESTOPTS: "-q --tty=no"
-          # Remove minitest from TEST_BUNDLED_GEMS_ALLOW_FAILURES if https://github.com/seattlerb/minitest/pull/798 is resolved
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: "minitest,xmlrpc,rexml"
-      - uses: k0kubun/action-slack@v2.0.0
+          TESTS: ${{ matrix.test_task == 'check' && matrix.skipped_tests || '' }}
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ""
+          PRECHECK_BUNDLED_GEMS: "no"
+      - name: make skipped tests
+        run: |
+          make -s test-all TESTS=`echo "$TESTS" | sed 's| |$$/ -n/|g;s|^|-n/|;s|$|$$/|'`
+        env:
+          GNUMAKEFLAGS: ""
+          RUBY_TESTOPTS: "-v --tty=no"
+          TESTS: ${{ matrix.skipped_tests }}
+          PRECHECK_BUNDLED_GEMS: "no"
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests != '' }}
+        continue-on-error: ${{ matrix.continue-on-skipped_tests || false }}
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
               "ci": "GitHub Actions",
-              "env": "${{ github.workflow }} / ${{ matrix.test_task }}",
+              "env": "${{ 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]
+              "branch": "${{ github.ref_name }}"
             }
         env:
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: failure() && github.event_name == 'push'
+        if: ${{ failure() && github.event_name == 'push' }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/mingw.yml b/.github/workflows/mingw.yml
index 95abd3300d..0df917d3d8 100644
--- a/.github/workflows/mingw.yml
+++ b/.github/workflows/mingw.yml
@@ -1,144 +1,179 @@
 name: MinGW
-on: [push, pull_request]
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.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') }}
+
+permissions:
+  contents: read
 
 # Notes:
 # Actions console encoding causes issues, see test-all & test-spec steps
 #
 jobs:
   make:
-    runs-on: windows-2019
+    runs-on: windows-2022
+    name: ${{ github.workflow }} (${{ matrix.msystem }})
     env:
-      MSYSTEM: MINGW64
-      MSYSTEM_PREFIX: /mingw64
+      MSYSTEM: ${{ matrix.msystem }}
       MSYS2_ARCH: x86_64
       CHOST: "x86_64-w64-mingw32"
-      CFLAGS:   "-march=x86-64 -mtune=generic -O3 -pipe -fstack-protector-strong"
+      CFLAGS:   "-march=x86-64 -mtune=generic -O3 -pipe"
       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"
+      LDFLAGS:  "-pipe"
       UPDATE_UNICODE: "UNICODE_FILES=. UNICODE_PROPERTY_FILES=. UNICODE_AUXILIARY_FILES=. UNICODE_EMOJI_FILES=."
       GITPULLOPTIONS: --no-tags origin ${{github.ref}}
     strategy:
       matrix:
-        test_task: [ "check" ] # to make job names consistent
+        include:
+          # To mitigate flakiness of MinGW CI, we test only one runtime that newer MSYS2 uses.
+          - msystem: "UCRT64"
+            base_ruby: head
+            test_task: "check"
+            test-all-opts: "--name=!/TestObjSpace#test_reachable_objects_during_iteration/"
       fail-fast: false
-    if: "!contains(github.event.head_commit.message, '[ci skip]')"
+    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
     steps:
+      - run: mkdir build
+        working-directory:
       - name: git config
         run: |
-          git config --system core.autocrlf false
-          git config --system core.eol lf
-          git config --system advice.detachedHead 0
-      - uses: actions/checkout@v2
+          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@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - run: ./src/tool/actions-commit-info.sh
-        shell: bash
-        id: commit_info
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: src/.downloaded-cache
+          key: downloaded-cache
       - name: Set up Ruby & MSYS2
-        uses: MSP-Greg/setup-ruby-pkgs@v1
+        uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
         with:
-          ruby-version: 2.6
-          mingw: _upgrade_ gdbm gmp libffi libyaml openssl ragel readline
-          msys2: automake1.16 bison
+          ruby-version: ${{ matrix.base_ruby }}
+      - name: set env
+        run: |
+          echo "GNUMAKEFLAGS=-j$((2 * NUMBER_OF_PROCESSORS))" >> $GITHUB_ENV
+
       - name: where check
         run: |
           # show where
-          Write-Host
-          $where = 'gcc.exe', 'ragel.exe', 'make.exe', 'bison.exe', 'libcrypto-1_1-x64.dll', 'libssl-1_1-x64.dll'
-          foreach ($e in $where) {
-            $rslt = where.exe $e 2>&1 | Out-String
-            if ($rslt.contains($e)) { Write-Host $rslt }
-            else { Write-Host "`nCan't find $e" }
-          }
-      - name: misc setup, autoreconf
+          mv /c/Windows/System32/libcrypto-1_1-x64.dll /c/Windows/System32/libcrypto-1_1-x64.dll_
+          mv /c/Windows/System32/libssl-1_1-x64.dll    /c/Windows/System32/libssl-1_1-x64.dll_
+          result=true
+          for e in gcc.exe ragel.exe make.exe bison.exe libcrypto-1_1-x64.dll libssl-1_1-x64.dll; do
+            echo '##['group']'$'\033[93m'$e$'\033[m'
+            where $e || result=false
+            echo '##['endgroup']'
+          done
+          $result
+
+      - name: version check
         run: |
-          mkdir build
-          mkdir install
-          mkdir temp
-          cd src
-          sh -c "autoreconf -fi"
+          # show version
+          result=true
+          for e in gcc ragel make bison "openssl version"; do
+            case "$e" in *" "*) ;; *) e="$e --version";; esac
+            echo '##['group']'$'\033[93m'$e$'\033[m'
+            $e || result=false
+            echo '##['endgroup']'
+          done
+          $result
 
-      - name: configure
-        working-directory: build
+      - name: autogen
         run: |
-          # Actions uses UTF8, causes test failures, similar to normal OS setup
-          $PSDefaultParameterValues['*:Encoding'] = 'utf8'
-          [Console]::OutputEncoding = [System.Text.Encoding]::GetEncoding("IBM437")
-          [Console]::InputEncoding  = [System.Text.Encoding]::GetEncoding("IBM437")
-          $config_args = "--build=$env:CHOST --host=$env:CHOST --target=$env:CHOST"
-          Write-Host $config_args
-          sh -c "../src/configure --disable-install-doc --prefix=/install $config_args"
-          # Write-Host "-------------------------------------- config.log"
-          # Get-Content ./config.log | foreach {Write-Output $_}
+          ./autogen.sh
+        working-directory: src
+
+      - name: configure
+        run: >
+          ../src/configure --disable-install-doc --prefix=/.
+          --build=$CHOST --host=$CHOST --target=$CHOST
 
       - name: update
-        working-directory: build
         run: |
-          $jobs = [int](2 * $env:NUMBER_OF_PROCESSORS)
-          make -j $jobs incs
+          make incs
 
       - name: download gems
-        working-directory: build
         run: |
-          $jobs = [int](2 * $env:NUMBER_OF_PROCESSORS)
-          make -j $jobs update-gems
+          make update-gems
 
       - name: make all
-        timeout-minutes: 40
-        working-directory: build
+        timeout-minutes: 30
         run: |
-          $jobs = [int](2 * $env:NUMBER_OF_PROCESSORS)
-          make -j $jobs
+          make
+
+      - run: make leaked-globals
 
       - name: make install
-        working-directory: build
         run: |
-          # Actions uses UTF8, causes test failures, similar to normal OS setup
-          $PSDefaultParameterValues['*:Encoding'] = 'utf8'
-          [Console]::OutputEncoding = [System.Text.Encoding]::GetEncoding("IBM437")
-          [Console]::InputEncoding  = [System.Text.Encoding]::GetEncoding("IBM437")
-          make DESTDIR=.. install-nodoc
+          make DESTDIR=../install install-nodoc
 
       - name: test
         timeout-minutes: 5
-        working-directory: build
         run: |
           make test
+        if: ${{matrix.test_task == 'check' || matrix.test_task == 'test'}}
 
       - name: test-all
-        timeout-minutes: 50
-        working-directory: build
+        timeout-minutes: 45
         run: |
           # Actions uses UTF8, causes test failures, similar to normal OS setup
-          $PSDefaultParameterValues['*:Encoding'] = 'utf8'
-          [Console]::OutputEncoding = [System.Text.Encoding]::GetEncoding("IBM437")
-          [Console]::InputEncoding  = [System.Text.Encoding]::GetEncoding("IBM437")
-          $jobs = [int](1.5 * $env:NUMBER_OF_PROCESSORS)
-          make test-all TESTOPTS="-j $jobs --retry --job-status=normal --show-skip --timeout-scale=1.5"
+          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
+            ${{ matrix.test-all-opts }}
+          BUNDLER_VERSION:
+        if: ${{matrix.test_task == 'check' || matrix.test_task == 'test-all' || StartsWith(matrix.test_task, 'test/')}}
 
       - name: test-spec
         timeout-minutes: 10
-        working-directory: src/spec/ruby
         run: |
-          $env:Path = "$pwd/../../../install/bin;$env:Path"
-          # Actions uses UTF8, causes test failures, similar to normal OS setup
-          $PSDefaultParameterValues['*:Encoding'] = 'utf8'
-          [Console]::OutputEncoding = [System.Text.Encoding]::GetEncoding("IBM437")
-          [Console]::InputEncoding  = [System.Text.Encoding]::GetEncoding("IBM437")
-          ruby -v
-          ruby ../mspec/bin/mspec -j
+          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/')}}
 
-      - uses: k0kubun/action-slack@v2.0.0
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
               "ci": "GitHub Actions",
-              "env": "${{ github.workflow }} / ${{ matrix.test_task }}",
+              "env": "${{ github.workflow }} ${{ matrix.msystem }} / ${{ matrix.test_task }}",
               "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
               "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
+              "branch": "${{ github.ref_name }}"
             }
         env:
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: failure() && github.event_name == 'push'
+        if: ${{ failure() && github.event_name == 'push' }}
+
+defaults:
+  run:
+    working-directory: build
+    shell: sh
diff --git a/.github/workflows/mjit-bindgen.yml b/.github/workflows/mjit-bindgen.yml
new file mode 100644
index 0000000000..26f8a1b2aa
--- /dev/null
+++ b/.github/workflows/mjit-bindgen.yml
@@ -0,0 +1,104 @@
+name: MJIT bindgen
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.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') }}
+
+permissions:
+  contents: read
+
+jobs:
+  make:
+    strategy:
+      matrix:
+        include:
+          - task: mjit-bindgen
+      fail-fast: false
+    runs-on: ubuntu-22.04
+    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
+        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 \
+          libclang1-14 \
+          bison autoconf
+          sudo apt-get install -q -y pkg-config || :
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
+        with:
+          ruby-version: '3.1'
+      - name: git config
+        run: |
+          git config --global advice.detachedHead 0
+          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          path: src
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        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 $d; done' || :
+      - run: ./autogen.sh
+        working-directory: src
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc --prefix=$(pwd)/install --enable-yjit=dev_nodebug
+      - run: make incs
+      - run: make
+      - run: make install
+      - run: make ${{ matrix.task }}
+      - run: git diff --exit-code
+        working-directory: src
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
+        with:
+          payload: |
+            {
+              "ci": "GitHub Actions",
+              "env": "${{ matrix.os }} / ${{ matrix.test_task }}${{ matrix.configure }}",
+              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              "commit": "${{ github.sha }}",
+              "branch": "${{ github.ref_name }}"
+            }
+        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
index 05d944b766..6f7181489a 100644
--- a/.github/workflows/mjit.yml
+++ b/.github/workflows/mjit.yml
@@ -1,32 +1,69 @@
 name: MJIT
-on: [push, pull_request]
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '**.[1-8]'
+      - '**.ronn'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '**.[1-8]'
+      - '**.ronn'
+
+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" ] # to make job names consistent
-        jit_opts: [ "--jit", "--jit-wait" ]
+        test_task: [check] # to make job names consistent
+        mjit_opts: [--mjit-wait]
       fail-fast: false
     runs-on: ubuntu-latest
-    if: "!contains(github.event.head_commit.message, '[ci skip]')"
+    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 --jit-warnings ${{ matrix.jit_opts }}'
+      RUN_OPTS: '--disable-gems ${{ matrix.mjit_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 libgdbm-dev bison autoconf ruby
+          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
-      - uses: actions/checkout@v2
+          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - run: ./src/tool/actions-commit-info.sh
-        id: commit_info
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: src/.downloaded-cache
+          key: downloaded-cache
       - name: Fixed world writable dirs
         run: |
           chmod -v go-w $HOME $HOME/.config
@@ -34,35 +71,43 @@ jobs:
           sudo bash -c 'IFS=:; for d in '"$PATH"'; do chmod -v go-w $d; done' || :
       - name: Set ENV
         run: |
-          echo '::set-env name=JOBS::'-j$((1 + $(nproc --all)))
-      - run: autoconf
+          echo "GNUMAKEFLAGS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
+      - run: ./autogen.sh
         working-directory: src
-      - run: mkdir build
       - name: Run configure
-        run: ../src/configure -C --disable-install-doc
-        working-directory: build
-      - run: make $JOBS incs
-        working-directory: build
-      - run: make $JOBS
-        working-directory: build
-      - run: sudo make $JOBS -s install
-        working-directory: build
-      - run: make $JOBS -s test
-        working-directory: build
-      - run: make $JOBS -s test-all
-        working-directory: build
-      - run: make $JOBS -s test-spec
-        working-directory: build
-      - uses: k0kubun/action-slack@v2.0.0
+        run: ../src/configure -C --disable-install-doc cppflags=-DVM_CHECK_MODE
+      - run: make incs
+      - run: make
+      - run: sudo make -s install
+      - name: Run test
+        run: |
+          unset GNUMAKEFLAGS
+          make -s test RUN_OPTS="$RUN_OPTS"
+        timeout-minutes: 60
+      # - name: Run test-all
+      #   run: |
+      #     ulimit -c unlimited
+      #     make -s test-all RUN_OPTS="$RUN_OPTS"
+      #   timeout-minutes: 60
+      - name: Run test-spec
+        run: |
+          unset GNUMAKEFLAGS
+          make -s test-spec RUN_OPTS="$RUN_OPTS"
+        timeout-minutes: 60
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
               "ci": "GitHub Actions",
-              "env": "${{ github.workflow }} / ${{ matrix.test_task }} ${{ matrix.jit_opts }}",
+              "env": "${{ github.workflow }} / ${{ matrix.test_task }} ${{ matrix.mjit_opts }}",
               "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
               "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
+              "branch": "${{ github.ref_name }}"
             }
         env:
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: failure() && github.event_name == 'push'
+        if: ${{ failure() && github.event_name == 'push' }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
new file mode 100644
index 0000000000..5d4474d978
--- /dev/null
+++ b/.github/workflows/publish.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/scorecards.yml b/.github/workflows/scorecards.yml
new file mode 100644
index 0000000000..c12a95362d
--- /dev/null
+++ b/.github/workflows/scorecards.yml
@@ -0,0 +1,72 @@
+# 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: Scorecards 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: '22 4 * * 2'
+  push:
+    branches: [ "master" ]
+
+# Declare default permissions as read only.
+permissions: read-all
+
+jobs:
+  analysis:
+    name: Scorecards analysis
+    runs-on: ubuntu-latest
+    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@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
+
+      - name: "Run analysis"
+        uses: ossf/scorecard-action@ea651e62978af7915d09fe2e282747c798bf2dab # v2.4.1
+        with:
+          results_file: results.sarif
+          results_format: sarif
+          # (Optional) Read-only 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 Scorecards on a *private* repository
+          # To create the PAT, follow the steps in https://github.com/ossf/scorecard-action#authentication-with-pat.
+          repo_token: ${{ secrets.SCORECARD_READ_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
+
+      # 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@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: SARIF file
+          path: results.sarif
+          retention-days: 5
+
+      # Upload the results to GitHub's code scanning dashboard.
+      - name: "Upload to code-scanning"
+        uses: github/codeql-action/upload-sarif@959cbb7472c4d4ad70cdfe6f4976053fe48ab394 # v2.1.27
+        with:
+          sarif_file: results.sarif
diff --git a/.github/workflows/spec_guards.yml b/.github/workflows/spec_guards.yml
new file mode 100644
index 0000000000..4521195a2b
--- /dev/null
+++ b/.github/workflows/spec_guards.yml
@@ -0,0 +1,71 @@
+name: Rubyspec Version Guards Check
+
+on:
+  push:
+    paths:
+      - 'spec/**'
+      - '!spec/*.md'
+  pull_request:
+    paths:
+      - '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-22.04
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.head_commit.message, 'Document')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.title, 'Document')
+      || contains(github.event.pull_request.labels.*.name, 'Document')
+      || (github.event_name == 'push' && github.actor == '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-3.1
+          - ruby-3.2
+
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler: none
+
+      - run: gem install webrick
+
+      - run: ruby ../mspec/bin/mspec
+        working-directory: spec/ruby
+        env:
+          CHECK_LEAKS: true
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
+        with:
+          payload: |
+            {
+              "ci": "GitHub Actions",
+              "env": "${{ github.workflow }} / rubyspec @ ${{ matrix.ruby }}",
+              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              "commit": "${{ github.sha }}",
+              "branch": "${{ github.ref_name }}"
+            }
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 0d81666e13..4fbca1170e 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -1,88 +1,146 @@
 name: Ubuntu
-on: [push, pull_request]
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.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') }}
+
+permissions:
+  contents: read
+
 jobs:
   make:
     strategy:
       matrix:
-        test_task: [ "check", "test-bundler-parallel", "test-bundled-gems", "test-all TESTS=--repeat-count=2", "leaked-globals" ]
-        os: [ubuntu-20.04, ubuntu-18.04, ubuntu-16.04]
-        debug: ["", "-DRUBY_DEBUG"]
-        exclude:
+        # main variables included in the job name
+        test_task: [check]
+        configure: [cppflags=-DRUBY_DEBUG] # default to use more assertions
+        arch: ['']
+        # specify all jobs with `include` to avoid testing duplicated things
+        include:
+          - test_task: check
+          - test_task: check
+            arch: i686
+            configure: '' # test without -DRUBY_DEBUG as well
+          - test_task: check
+            configure: "--enable-shared --enable-load-relative"
+          - test_task: test-all TESTS=--repeat-count=2
           - test_task: test-bundler-parallel
-            os: ubuntu-16.04
           - test_task: test-bundled-gems
-            os: ubuntu-16.04
-          - test_task: "test-all TESTS=--repeat-count=2"
-            os: ubuntu-16.04
-          - test_task: leaked-globals
-            os: ubuntu-16.04
-          - os: ubuntu-16.04
-            debug: -DRUBY_DEBUG
-          - test_task: "test-all TESTS=--repeat-count=2"
-            debug: -DRUBY_DEBUG
-          - test_task: leaked-globals
-            debug: -DRUBY_DEBUG
       fail-fast: false
     env:
       GITPULLOPTIONS: --no-tags origin ${{github.ref}}
-    runs-on: ${{ matrix.os }}
-    if: "!contains(github.event.head_commit.message, '[ci skip]')"
+      RUBY_DEBUG: ci
+      SETARCH: ${{ matrix.arch && format('setarch {0}', matrix.arch) }}
+    runs-on: ubuntu-22.04
+    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 build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev libgdbm-dev bison autoconf ruby
+          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
-      - uses: actions/checkout@v2
+          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - run: ./src/tool/actions-commit-info.sh
-        id: commit_info
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        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 $d; done' || :
-      - name: Set ENV
-        run: |
-          echo '::set-env name=JOBS::'-j$((1 + $(nproc --all)))
-      - run: autoconf
+      - run: ./autogen.sh
         working-directory: src
-      - run: mkdir build
       - name: Run configure
-        run: ../src/configure -C --disable-install-doc cppflags=${{ matrix.debug }}
-        working-directory: build
-      - run: make $JOBS incs
-        working-directory: build
-      - run: make $JOBS
-        working-directory: build
-      - run: make prepare-gems
-        working-directory: build
-        if: matrix.test_task == 'check'
+        env:
+          arch: ${{matrix.arch}}
+        run: >-
+          $SETARCH ../src/configure -C --disable-install-doc ${{ matrix.configure }}
+          ${arch:+--target=$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: |
-          ./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)")}'
-        working-directory: build
-        if: matrix.test_task == 'check'
-      - run: make $JOBS -s ${{ matrix.test_task }}
-        working-directory: build
+          $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' }}
+      - 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
         env:
           RUBY_TESTOPTS: "-q --tty=no"
-          # Remove minitest from TEST_BUNDLED_GEMS_ALLOW_FAILURES if https://github.com/seattlerb/minitest/pull/798 is resolved
-          TEST_BUNDLED_GEMS_ALLOW_FAILURES: "minitest,xmlrpc"
-      - uses: k0kubun/action-slack@v2.0.0
+          TESTS: ${{ matrix.test_task == 'check' && matrix.skipped_tests || '' }}
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ""
+          PRECHECK_BUNDLED_GEMS: "no"
+      - name: make skipped tests
+        run: |
+          $SETARCH make -s test-all TESTS=`echo "$TESTS" | sed 's| |$$/ -n/|g;s|^|-n/|;s|$|$$/|'`
+        env:
+          GNUMAKEFLAGS: ""
+          RUBY_TESTOPTS: "-v --tty=no"
+          TESTS: ${{ matrix.skipped_tests }}
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests != '' }}
+        continue-on-error: ${{ matrix.continue-on-skipped_tests || false }}
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
               "ci": "GitHub Actions",
-              "env": "${{ matrix.os }} / ${{ matrix.test_task }}${{ matrix.debug }}",
+              "env": "${{ github.workflow }} / ${{ matrix.test_task }} ${{ matrix.configure }}${{ matrix.arch }}",
               "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
               "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
+              "branch": "${{ github.ref_name }}"
             }
         env:
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: failure() && github.event_name == 'push'
+        if: ${{ failure() && github.event_name == 'push' }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/wasm.yml b/.github/workflows/wasm.yml
new file mode 100644
index 0000000000..27920b5821
--- /dev/null
+++ b/.github/workflows/wasm.yml
@@ -0,0 +1,146 @@
+name: WebAssembly
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.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') }}
+
+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" }
+#         # -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" }
+      fail-fast: false
+    env:
+      RUBY_TESTOPTS: '-q --tty=no'
+      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
+      WASI_SDK_VERSION_MAJOR: 14
+      WASI_SDK_VERSION_MINOR: 0
+      BINARYEN_VERSION: 109
+      WASMTIME_VERSION: v0.33.0
+    runs-on: ubuntu-22.04
+    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+    steps:
+      - run: mkdir build
+        working-directory:
+      - name: git config
+        run: |
+          git config --global advice.detachedHead 0
+          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          path: src
+      - name: Install libraries
+        run: |
+          set -ex
+          sudo apt-get update -q || :
+          sudo apt-get install --no-install-recommends -q -y ruby bison make autoconf git wget
+
+          wasi_sdk_deb="wasi-sdk_${WASI_SDK_VERSION_MAJOR}.${WASI_SDK_VERSION_MINOR}_amd64.deb"
+          wget "https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-${WASI_SDK_VERSION_MAJOR}/${wasi_sdk_deb}"
+          sudo dpkg -i "$wasi_sdk_deb"
+          rm -f "$wasi_sdk_deb"
+
+          mkdir build-sdk
+          pushd build-sdk
+
+          wasmtime_url="https://github.com/bytecodealliance/wasmtime/releases/download/${WASMTIME_VERSION}/wasmtime-${WASMTIME_VERSION}-x86_64-linux.tar.xz"
+          wget -O - "$wasmtime_url" | tar xJf -
+          sudo ln -fs "$PWD/wasmtime-${WASMTIME_VERSION}-x86_64-linux/wasmtime" /usr/local/bin/wasmtime
+
+          binaryen_tarball="binaryen-version_${BINARYEN_VERSION}-x86_64-linux.tar.gz"
+          binaryen_url="https://github.com/WebAssembly/binaryen/releases/download/version_${BINARYEN_VERSION}/${binaryen_tarball}"
+          wget -O - "$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" >> $GITHUB_ENV
+      - run: ./autogen.sh
+        working-directory: src
+
+      - uses: ruby/setup-ruby@13e7a03dc3ac6c3798f4570bfead2aed4d96abfb # v1.244.0
+        with:
+          ruby-version: '3.0'
+          bundler: none
+
+      - name: Download config.guess with wasi version
+        run: |
+          rm tool/config.guess tool/config.sub
+          ruby tool/downloader.rb -d tool -e gnu config.guess config.sub
+        working-directory: src
+
+      - name: Run configure
+        run: |
+          ../src/configure \
+            --host wasm32-unknown-wasi \
+            --with-static-linked-ext \
+            LDFLAGS=" \
+              -Xlinker --stack-first \
+              -Xlinker -z -Xlinker stack-size=16777216 \
+            " \
+            optflags="${{ matrix.entry.optflags }}" \
+            debugflags="${{ matrix.entry.debugflags }}" \
+            wasmoptflags="${{ matrix.entry.wasmoptflags }} ${{ matrix.entry.debugflags }}"
+
+      # miniruby may not be built when cross-compling
+      - run: make mini ruby
+      - name: Run basictest
+        run: wasmtime run ./../build/miniruby --mapdir /::./ -- basictest/test.rb
+        working-directory: src
+      - name: Run bootstraptest (no thread)
+        run: |
+          NO_THREAD_TESTS="$(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: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
+        with:
+          payload: |
+            {
+              "ci": "GitHub Actions",
+              "env": "${{ github.workflow }} / ${{ matrix.name }}",
+              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              "commit": "${{ github.sha }}",
+              "branch": "${{ github.ref_name }}"
+            }
+        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/windows.yml b/.github/workflows/windows.yml
index 2f1f3a7570..c2bd4881c2 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -1,81 +1,149 @@
 name: Windows
-on: [push, pull_request]
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.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') }}
+
+permissions:
+  contents: read
+
 jobs:
   make:
     strategy:
       matrix:
-        test_task: [test]
-        os: [windows-2019]
-        vs: [2019]
+        include:
+          - vs: 2022
+            vcvers: -vcvars_ver=14.2
       fail-fast: false
-    runs-on: ${{ matrix.os }}
+    runs-on: windows-${{ matrix.vs }}
+    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+    name: VisualStudio ${{ matrix.vs }}
     env:
       GITPULLOPTIONS: --no-tags origin ${{github.ref}}
-    if: "!contains(github.event.head_commit.message, '[ci skip]')"
+      PATCH: C:\msys64\usr\bin\patch.exe
+      OS_VER: windows-${{ matrix.vs }}
     steps:
-      - uses: actions/cache@v1
+      - run: md build
+        working-directory:
+      - uses: msys2/setup-msys2@61f9e5e925871ba6c9e3e8da24ede83ea27fa91f # v2.27.0
+        id: setup-msys2
         with:
-          path: C:\vcpkg\downloads
-          key: ${{ runner.os }}-vcpkg-download-${{ matrix.os }}-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-vcpkg-download-${{ matrix.os }}-
-            ${{ runner.os }}-vcpkg-download-
-      - name: Install libraries with vcpkg
-        run: |
-          vcpkg --triplet x64-windows install readline zlib
-      - uses: actions/cache@v1
+          update: true
+          install: bison patch
+      - name: patch path
+        shell: msys2 {0}
+        run: echo PATCH=$(cygpath -wa $(command -v patch)) >> $GITHUB_ENV
+        if: ${{ steps.setup-msys2.outcome == 'success' }}
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
-          path: C:\Users\runneradmin\AppData\Local\Temp\chocolatey
-          key: ${{ runner.os }}-chocolatey-${{ matrix.os }}-${{ github.sha }}
+          path: C:\vcpkg\installed
+          key: ${{ runner.os }}-vcpkg-installed-windows-${{ matrix.vs }}-${{ github.sha }}
           restore-keys: |
-            ${{ runner.os }}-chocolatey-${{ matrix.os }}-
-            ${{ runner.os }}-chocolatey-
-      - name: Install libraries with chocolatey
+            ${{ runner.os }}-vcpkg-installed-windows-${{ matrix.vs }}-
+            ${{ runner.os }}-vcpkg-installed-windows-
+      - name: Install libraries with vcpkg
         run: |
-          choco install --no-progress openssl winflexbison3
+          iex "& {$(irm get.scoop.sh)} -RunAsAdmin"
+          Join-Path (Resolve-Path ~).Path "scoop\shims" >> $Env:GITHUB_PATH
+          scoop install cmake@3.31.6
+          vcpkg --triplet x64-windows install libffi libyaml openssl readline zlib
+        shell:
+          pwsh
       - name: git config
         run: |
-          git config --system advice.detachedHead 0
-      - uses: actions/checkout@v2
+          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@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           path: src
-      - run: ./src/tool/actions-commit-info.sh
-        shell: bash
-        id: commit_info
-      - run: md build
-        shell: cmd
-      - name: Configure
-        run: |
-          call "C:\Program Files (x86)\Microsoft Visual Studio\${{ matrix.vs }}\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
-          ../src/win32/configure.bat --disable-install-doc --without-ext=+,dbm,gdbm --enable-bundled-libffi --with-opt-dir=C:/vcpkg/installed/x64-windows --with-openssl-dir="C:/Program Files/OpenSSL-Win64"
-        working-directory: build
-        shell: cmd
-      - name: nmake
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: src/.downloaded-cache
+          key: downloaded-cache
+      - name: setup env
+        # %TEMP% is inconsistent with %TMP% and test-all expects they are consistent.
+        # https://github.com/actions/virtual-environments/issues/712#issuecomment-613004302
+        # msys2/setup-msys2 installs MSYS2 to D:/a/_temp/msys64/usr/bin
         run: |
-          call "C:\Program Files (x86)\Microsoft Visual Studio\${{ matrix.vs }}\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
-          set YACC=win_bison
-          echo on
-          nmake incs
-          nmake extract-extlibs
-          nmake
-        working-directory: build
-        shell: cmd
-      - name: nmake test
+          set Path=D:/a/_temp/msys64/usr/bin;%Path%
+          if not "%VCVARS%" == "" goto :vcset
+            set VCVARS="C:\Program Files (x86)\Microsoft Visual Studio\${{ matrix.vs }}\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
+            if not exist %VCVARS% set VCVARS="C:\Program Files\Microsoft Visual Studio\${{ matrix.vs }}\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
+          :vcset
+          set | C:\msys64\usr\bin\sort > old.env
+          call %VCVARS% ${{ matrix.vcvers || ''}}
+          set TMP=%USERPROFILE%\AppData\Local\Temp
+          set TEMP=%USERPROFILE%\AppData\Local\Temp
+          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%
+          del *.env
+      - name: compiler version
+        run: cl
+      - name: link libraries
         run: |
-          call "C:\Program Files (x86)\Microsoft Visual Studio\${{ matrix.vs }}\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
-          nmake ${{ matrix.test_task }}
-        working-directory: build
-        shell: cmd
-      - uses: k0kubun/action-slack@v2.0.0
+          for %%I in (C:\vcpkg\installed\x64-windows\bin\*.dll) do (
+            if not %%~nI == readline mklink %%~nxI %%I
+          )
+          for %%I in (libcrypto-1_1-x64 libssl-1_1-x64) do (
+            ren c:\Windows\System32\%%I.dll %%I.dll_
+          )
+      - name: Configure
+        run: >-
+          ../src/win32/configure.bat --disable-install-doc
+          --with-opt-dir=C:/vcpkg/installed/x64-windows
+      - run: nmake incs
+      - run: nmake extract-extlibs
+      - run: nmake
+        env:
+          YACC: bison.exe
+      - run: nmake test
+        timeout-minutes: 5
+      - run: nmake test-spec
+        timeout-minutes: 10
+      - run: nmake test-all
+        env:
+          RUBY_TESTOPTS: -j${{env.TEST_JOBS}} --job-status=normal
+        timeout-minutes: 60
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
         with:
           payload: |
             {
               "ci": "GitHub Actions",
-              "env": "${{ matrix.os }} / ${{ matrix.test_task }}",
+              "env": "VS${{ matrix.vs }} / ${{ matrix.test_task || 'check' }}",
               "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
               "commit": "${{ github.sha }}",
-              "branch": "${{ github.ref }}".split('/').reverse()[0]
+              "branch": "${{ github.ref_name }}"
             }
         env:
           SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
-        if: failure() && github.event_name == 'push'
+        if: ${{ failure() && github.event_name == 'push' }}
+
+defaults:
+  run:
+    working-directory: build
+    shell: cmd
diff --git a/.github/workflows/yjit-ubuntu.yml b/.github/workflows/yjit-ubuntu.yml
new file mode 100644
index 0000000000..0b7b9046e9
--- /dev/null
+++ b/.github/workflows/yjit-ubuntu.yml
@@ -0,0 +1,170 @@
+name: YJIT Ubuntu
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  pull_request:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+  merge_group:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man'
+      - '**.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') }}
+
+permissions:
+  contents: read
+
+jobs:
+  cargo:
+    name: Rust cargo test
+    # GitHub Action's image seems to already contain a Rust 1.58.0.
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      # 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
+  make:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - test_task: 'yjit-bindgen'
+            hint: 'To fix: use patch in logs'
+            configure: '--with-gcc=clang-14 --enable-yjit=dev'
+            libclang_path: '/usr/lib/llvm-14/lib/libclang.so.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"
+            yjit_opts: "--yjit-call-threshold=1 --yjit-verify-ctx"
+
+          - test_task: "test-all TESTS=--repeat-count=2"
+            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}}
+      RUN_OPTS: ${{ matrix.yjit_opts }}
+      YJIT_BENCH_OPTS: ${{ matrix.yjit_bench_opts }}
+      RUBY_DEBUG: ci
+      BUNDLE_JOBS: 8 # for yjit-bench
+    runs-on: ubuntu-22.04
+    if: ${{ !contains(github.event.head_commit.message, '[DOC]') && !contains(github.event.pull_request.labels.*.name, 'Documentation') }}
+    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: 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@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          path: src
+      - uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        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)))" >> $GITHUB_ENV
+      - run: ./autogen.sh
+        working-directory: src
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc --prefix=$(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: |
+          ./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
+      # Check that the binary was built with YJIT
+      - name: Check YJIT enabled
+        run: ./miniruby --yjit -v | grep "+YJIT"
+      - 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"
+          LIBCLANG_PATH: ${{ matrix.libclang_path }}
+        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}"
+        env:
+          BASE_REPO: ${{ github.event.pull_request.base.repo.full_name }}
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+        if: ${{ matrix.test_task == 'yjit-bench' && startsWith(github.event_name, 'pull') }}
+      - uses: ruby/action-slack@0bd85c72233cdbb6a0fe01d37aaeff1d21b5fce1 # v3.2.1
+        with:
+          payload: |
+            {
+              "ci": "GitHub Actions",
+              "env": "${{ github.workflow }} / ${{ matrix.test_task }} ${{ matrix.configure }}",
+              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              "commit": "${{ github.sha }}",
+              "branch": "${{ github.ref_name }}"
+            }
+        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/.gitignore b/.gitignore
index c79485a0b5..99d32a1825 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,9 +10,11 @@
 *.dylib
 *.elc
 *.i
+*.ii
 *.inc
 *.log
 *.o
+*.o.tmp
 *.obj
 *.old
 *.orig
@@ -24,6 +26,7 @@
 *.sav
 *.sl
 *.so
+*.so.*
 *.swp
 *.yarb
 *~
@@ -126,8 +129,10 @@ lcov*.info
 /ruby-runner
 /ruby-runner.h
 /ruby-man.rd.gz
+/rubyspec_temp
 /run.gdb
 /sizes.c
+/static-ruby
 /test.rb
 /test-coverage.dat
 /tmp
@@ -142,6 +147,8 @@ lcov*.info
 
 /bin/*.exe
 /bin/*.dll
+/bin/goruby
+/bin/ruby
 
 # /benchmark/
 /benchmark/bm_require.data
@@ -181,6 +188,9 @@ lcov*.info
 /ext/-test-/win32/dln/dlntest.exp
 /ext/-test-/win32/dln/dlntest.lib
 
+# /ext/-test-/gems
+/ext/-test-/gems
+
 # /ext/etc/
 /ext/etc/constdefs.h
 
@@ -213,6 +223,9 @@ lcov*.info
 /lib/ruby/[1-9]*.*
 /lib/ruby/vendor_ruby
 
+# /misc/
+/misc/**/__pycache__
+
 # /spec/bundler
 /.rspec_status
 
@@ -224,6 +237,14 @@ lcov*.info
 /win32/*.ico
 
 # MJIT
-/rb_mjit_header.h
-/mjit_config.h
 /include/ruby-*/*/rb_mjit_min_header-*.h
+/lib/ruby_vm/mjit/instruction.rb
+/mjit_config.h
+/rb_mjit_header.h
+
+# YJIT
+/yjit-bench
+/yjit_exit_locations.dump
+
+# /wasm/
+/wasm/tests/*.wasm
diff --git a/.indent.pro b/.indent.pro
new file mode 100644
index 0000000000..1d61cbcad1
--- /dev/null
+++ b/.indent.pro
@@ -0,0 +1,32 @@
+-bap
+-nbbb
+-nbc
+-br
+-brs
+-nbs
+-ncdb
+-nce
+-cdw
+-cli2
+-cbi2
+-ndj
+-ncs
+-nfc1
+-i4
+-l120
+-lp
+-npcs
+-psl
+-sc
+-sob
+-sbi4
+-nut
+-par
+
+-TID
+-TVALUE
+-Tst_data_t
+-Tst_index_t
+-Tst_table
+-Trb_data_type_t
+-TFILE
diff --git a/.rdoc_options b/.rdoc_options
new file mode 100644
index 0000000000..760507c7a2
--- /dev/null
+++ b/.rdoc_options
@@ -0,0 +1,4 @@
+---
+page_dir: doc
+main_page: README.md
+title: Documentation for Ruby development version
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 59f50283db..0000000000
--- a/.travis.yml
+++ /dev/null
@@ -1,541 +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.
-
-# This is  a Travis-CI  build configuration file.   The list  of configurations
-# available is located in
-#
-#     http://about.travis-ci.org/docs/user/build-configuration/
-#
-# and as Ruby itself is a project written in C language,
-#
-#     http://about.travis-ci.org/docs/user/languages/c/
-#
-# is also a good place to look at.
-
-language: c
-
-os: linux
-
-dist: xenial
-
-git:
-  quiet: true
-
-cache:
-  ccache: true
-  directories:
-    - $HOME/config_2nd
-    - $HOME/.downloaded-cache
-
-env:
-  global:
-    # Reset timestamps early
-    - _=$(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'
-    - UPDATE_UNICODE="UNICODE_FILES=. UNICODE_PROPERTY_FILES=. UNICODE_AUXILIARY_FILES=. UNICODE_EMOJI_FILES=."
-    - BEFORE_INSTALL=true
-    # 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"
-
-.org.ruby-lang.ci.matrix-definitions:
-
-  - &cron-only
-    if: (type = cron) AND (branch = master) AND (fork = false)
-
-  - &make-test-only
-    script:
-      - $SETARCH make -s test TESTOPTS="${TESTOPTS=$JOBS -q --tty=no}"
-
-  - &gcc-8
-    compiler: gcc-8
-    # # Not using addon to control retries
-    # addons:
-    #   apt:
-    #     sources:
-    #       - ubuntu-toolchain-r-test
-    before_install:
-      - bash -cx "${BEFORE_INSTALL}"
-      - tool/travis_retry.sh sudo -E apt-add-repository -y "ppa:ubuntu-toolchain-r/test"
-      - 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 $travis_apt_get_options install
-        ccache
-        gcc-8
-        g++-8
-        libffi-dev
-        libgdbm-dev
-        libgmp-dev
-        libjemalloc-dev
-        libncurses5-dev
-        libncursesw5-dev
-        libreadline6-dev
-        libssl-dev
-        libyaml-dev
-        openssl
-        valgrind
-        zlib1g-dev
-
-  - &clang-8
-    compiler: clang-8
-    addons:
-      apt:
-        # Not doing this manually unlike other sources, because it has been stable.
-        sources:
-          - llvm-toolchain-xenial-8
-        config:
-          retries: true
-    before_install:
-      - tool/travis_retry.sh sudo bash -c "rm -rf '${TRAVIS_ROOT}/var/lib/apt/lists/'* && exec apt-get update -yq"
-      - >-
-        tool/travis_retry.sh sudo -E apt-get $travis_apt_get_options install
-        clang-8
-        llvm-8-tools
-        libffi-dev
-        libgdbm-dev
-        libgmp-dev
-        libjemalloc-dev
-        libncurses5-dev
-        libncursesw5-dev
-        libreadline6-dev
-        libssl-dev
-        libyaml-dev
-        openssl
-        valgrind
-        zlib1g-dev
-
-  # --------
-
-  - &x86_64-linux
-    name: x86_64-linux
-    <<: *gcc-8
-
-  - &arm64-linux
-    name: arm64-linux
-    arch: arm64
-    <<: *gcc-8
-
-  - &s390x-linux
-    name: s390x-linux
-    arch: s390x
-    <<: *gcc-8
-
-  - &jemalloc
-    name: --with-jemalloc
-    <<: *gcc-8
-    <<: *cron-only
-    env:
-      - CONFIG_FLAG='--with-gmp --with-jemalloc --with-valgrind'
-
-  - &assertions
-    name: RUBY_DEBUG=1
-    <<: *gcc-8
-    #<<: *cron-only
-    <<: *make-test-only
-    env:
-      - GEMS_FOR_TEST=
-      - cppflags='-DRUBY_DEBUG -DVM_CHECK_MODE=1 -DTRANSIENT_HEAP_CHECK_MODE -DRGENGC_CHECK_MODE -DENC_DEBUG'
-
-  - &VM_CHECK_MODE
-    name: VM_CHECK_MODE=3
-    <<: *gcc-8
-    <<: *cron-only
-    <<: *make-test-only
-    env:
-      - GEMS_FOR_TEST=
-      - cppflags=-DVM_CHECK_MODE=0x0003
-
-  - &SUPPORT_JOKE
-    name: SUPPORT_JOKE
-    <<: *gcc-8
-    <<: *cron-only
-    <<: *make-test-only
-    env:
-      - BEFORE_INSTALL="sed vm_opts.h -e 's/OPT_SUPPORT_JOKE *0/OPT_SUPPORT_JOKE 1/' -i"
-
-  - &CPDEBUG
-    name: CPDEBUG
-    <<: *gcc-8
-    <<: *cron-only
-    <<: *make-test-only
-    env:
-      - cppflags=-DCPDEBUG
-
-  - &WITH_COROUTINE_UCONTEXT
-    name: COROUTINE=ucontext
-    <<: *gcc-8
-    <<: *cron-only
-    env:
-      - CONFIG_FLAG='--with-coroutine=ucontext'
-
-  - &WITH_COROUTINE_COPY
-    name: COROUTINE=copy
-    <<: *gcc-8
-    <<: *cron-only
-    env:
-      - CONFIG_FLAG='--with-coroutine=copy'
-
-  - &TOKEN_THREADED_CODE
-    name: TOKEN_THREADED_CODE
-    <<: *gcc-8
-    <<: *cron-only
-    <<: *make-test-only
-    env:
-      - GEMS_FOR_TEST=
-      - cppflags=-DOPT_THREADED_CODE=1
-
-  - &CALL_THREADED_CODE
-    name: CALL_THREADED_CODE
-    <<: *gcc-8
-    <<: *cron-only
-    <<: *make-test-only
-    env:
-      - GEMS_FOR_TEST=
-      - cppflags=-DOPT_THREADED_CODE=2
-
-  - &NO_THREADED_CODE
-    name: NO_THREADED_CODE
-    <<: *gcc-8
-    <<: *cron-only
-    <<: *make-test-only
-    env:
-      - GEMS_FOR_TEST=
-      - cppflags=-DOPT_THREADED_CODE=3
-
-  - &ASAN
-    name: -fsanitize=address
-    <<: *clang-8
-    #<<: *cron-only
-    <<: *make-test-only
-    env:
-      - GEMS_FOR_TEST=
-      - ASAN_OPTIONS=detect_leaks=0
-      - cflags='-U_FORTIFY_SOURCE -march=native -fsanitize=address -fno-omit-frame-pointer -fPIC'
-      - debugflags=-ggdb3
-      - optflags=-O1
-      - LD=clang-8
-      - LDFLAGS='-fsanitize=address -fPIC'
-      - CONFIG_FLAG='--with-out-ext=openssl --without-gmp --without-jemalloc --without-valgrind'
-
-  - &MSAN
-    name: -fsanitize=memory
-    <<: *clang-8
-    #<<: *cron-only
-    <<: *make-test-only
-    env:
-      - GEMS_FOR_TEST=
-      - cflags='-U_FORTIFY_SOURCE -fsanitize=memory -fsanitize-memory-track-origins=2 -fno-omit-frame-pointer -fPIC'
-      - optflags=-O1
-      - LD=clang-8
-      - LDFLAGS='-fsanitize=memory -fPIC'
-      - CONFIG_FLAG='--with-out-ext=openssl --without-gmp --without-jemalloc --without-valgrind'
-
-  - &UBSAN
-    name: -fsanitize=undefined
-    <<: *clang-8
-    #<<: *cron-only
-    <<: *make-test-only
-    env:
-      - GEMS_FOR_TEST=
-      - cflags='-U_FORTIFY_SOURCE -fsanitize=undefined,integer,nullability -fno-sanitize=implicit-integer-sign-change,unsigned-integer-overflow'
-      - cppflags=-DUNALIGNED_WORD_ACCESS=0
-      - debugflags=-ggdb3
-      - optflags='-O1 -march=native'
-      - LD=clang-8
-      - LDFLAGS='-fsanitize=undefined,integer,nullability -fno-sanitize=implicit-integer-sign-change,unsigned-integer-overflow'
-
-  - &i686-linux
-    name: i686-linux
-    compiler: gcc-8
-    env:
-      - GCC_FLAGS=-m32
-      - CXX='g++-8 -m32'
-      - debugflags=-g0
-      - SETARCH='setarch i686 --verbose --3gb'
-    # # Not using addon to control retries
-    # addons:
-    #   apt:
-    #     sources:
-    #       - ubuntu-toolchain-r-test
-    before_install:
-      - tool/travis_retry.sh sudo -E apt-add-repository -y "ppa:ubuntu-toolchain-r/test"
-      - 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 $travis_apt_get_options install
-        gcc-8-multilib
-        g++-8
-        g++-8-multilib
-        libstdc++-8-dev:i386
-        libffi-dev:i386
-        libffi6:i386
-        libgdbm-dev:i386
-        libgdbm3:i386
-        libncurses5-dev:i386
-        libncurses5:i386
-        libncursesw5-dev:i386
-        libreadline6-dev:i386
-        libreadline6:i386
-        libssl-dev:i386
-        libssl1.0.0:i386
-        linux-libc-dev:i386
-        zlib1g-dev:i386
-        zlib1g:i386
-
-  - &arm32-linux
-    name: arm32-linux
-    arch: arm64
-    # https://packages.ubuntu.com/xenial/crossbuild-essential-armhf
-    compiler: arm-linux-gnueabihf-gcc
-    env:
-      - debugflags=-g0
-      - SETARCH='setarch linux32 --verbose --32bit'
-    before_install:
-      - sudo dpkg --add-architecture armhf
-      - tool/travis_retry.sh sudo bash -c "rm -rf '${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++-5-dev:armhf
-        libffi-dev:armhf
-        libffi6:armhf
-        libgdbm-dev:armhf
-        libgdbm3:armhf
-        libncurses5-dev:armhf
-        libncurses5:armhf
-        libncursesw5-dev:armhf
-        libreadline6-dev:armhf
-        libreadline6:armhf
-        libssl-dev:armhf
-        libssl1.0.0:armhf
-        linux-libc-dev:armhf
-        zlib1g-dev:armhf
-        zlib1g:armhf
-
-  - &pedanticism
-    name: -std=c99 -pedantic
-    compiler: clang
-    <<: *make-test-only
-    env:
-      - GEMS_FOR_TEST=
-      - GCC_FLAGS='-std=c99 -Werror=pedantic -pedantic-errors'
-      - CONFIG_FLAG=
-      - JOBS=
-      - >-
-        warnflags='
-        -Wall
-        -Wextra
-        -Werror=deprecated-declarations
-        -Werror=division-by-zero
-        -Werror=extra-tokens
-        -Werror=implicit-function-declaration
-        -Werror=implicit-int
-        -Werror=pointer-arith
-        -Werror=shorten-64-to-32
-        -Werror=write-strings
-        -Wmissing-noreturn
-        -Wno-constant-logical-operand
-        -Wno-missing-field-initializers
-        -Wno-overlength-strings
-        -Wno-parentheses-equality
-        -Wno-self-assign
-        -Wno-tautological-compare
-        -Wno-unused-local-typedef
-        -Wno-unused-parameter
-        -Wunused-variable'
-      - LDFLAGS=-Wno-unused-command-line-argument
-
-  - &spec-on-old-ruby
-    language: ruby
-    before_install:
-    install:
-    before_script: chmod -R u+w spec/ruby
-    # -j randomly hangs.
-    script: ruby -C spec/ruby ../mspec/bin/mspec .
-
-  - &rubyspec25
-    name: Check ruby/spec version guards on Ruby 2.5
-    rvm: 2.5.7
-    <<: *spec-on-old-ruby
-    after_failure:
-      - echo "ruby/spec failed on Ruby 2.5. This is likely because of a missing ruby_version_is guard, please add it. See spec/README.md."
-
-  - &rubyspec27
-    name: Check ruby/spec version guards on Ruby 2.7
-    rvm: 2.7.0
-    <<: *spec-on-old-ruby
-    after_failure:
-      - echo "ruby/spec failed on Ruby 2.7. This is likely because of a missing ruby_version_is guard, please add it. See spec/README.md."
-
-  - &baseruby
-    name: "BASERUBY: Ruby 2.2"
-    <<: *gcc-8
-    <<: *make-test-only
-    language: ruby
-    rvm: 2.2
-
-  - &dependency
-    name: Check dependencies in makefiles
-    language: ruby
-    before_install:
-    install:
-    before_script:
-      - |-
-        ruby -e 'new = []
-          Dir.glob("ext/**/extconf.rb") {|ex|
-            unless File.exist?(dep = File.dirname(ex)+"/depend")
-              puts "Adding "+dep
-              File.copy_stream("template/depend.tmpl", dep)
-              new << dep
-            end
-          }
-          exec("git", "add", *new) unless new.empty?'
-      - git diff --cached
-      - "> config.status"
-      - "> .rbconfig.time"
-      - sed -f tool/prereq.status template/Makefile.in common.mk > Makefile
-      - make touch-unicode-files
-      - make -s $JOBS $UPDATE_UNICODE -o update-src up
-      - make -s $JOBS srcs
-      - rm -f config.status Makefile rbconfig.rb .rbconfig.time
-      - $SETARCH ./configure -C --disable-install-doc --prefix=$RUBY_PREFIX --disable-rubygems 'optflags=-O0' 'debugflags=-save-temps=obj -g'
-      - ruby tool/update-deps --fix
-    script:
-      - git diff --no-ext-diff --ignore-submodules --exit-code
-    after_failure:
-      - echo "Dependencies need to update"
-    env:
-      - CONFIG_FLAG=
-
-matrix:
-  include:
-    # Build every commit:
-    - <<: *x86_64-linux
-    - <<: *i686-linux
-    - <<: *pedanticism
-    - <<: *assertions
-    - <<: *baseruby
-    - <<: *rubyspec25
-    - <<: *rubyspec27
-    - <<: *dependency
-    # Build every commit (Allowed Failures):
-    - <<: *arm32-linux
-    - <<: *arm64-linux
-    - <<: *s390x-linux
-    - <<: *ASAN
-    - <<: *MSAN
-    - <<: *UBSAN
-    # Cron only:
-    - <<: *jemalloc
-    - <<: *VM_CHECK_MODE
-    - <<: *SUPPORT_JOKE
-    - <<: *CPDEBUG
-    - <<: *WITH_COROUTINE_UCONTEXT
-    - <<: *WITH_COROUTINE_COPY
-    - <<: *TOKEN_THREADED_CODE
-    - <<: *CALL_THREADED_CODE
-    - <<: *NO_THREADED_CODE
-  allow_failures:
-    - name: arm32-linux
-    - name: arm64-linux
-    - name: s390x-linux
-    - name: -fsanitize=address
-    - name: -fsanitize=memory
-  fast_finish: true
-
-before_script:
-  - 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 touch-unicode-files
-  - make -s $JOBS $UPDATE_UNICODE up
-  - make -s $JOBS srcs
-  - rm -f config.status Makefile rbconfig.rb .rbconfig.time
-  - |-
-    if [ -d ~/config_2nd ]; then
-      cp -pr ~/config_2nd build
-    else
-      mkdir build
-    fi
-  - mkdir config_1st config_2nd
-  - chmod -R a-w .
-  - chmod -R u+w build config_1st config_2nd
-  - cd build
-  - |-
-    case "$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}"
-  - travis_wait 50 $SETARCH make -s test-all -o exts TESTOPTS="${TESTOPTS} ${TEST_ALL_OPTS}" RUBYOPT="-w"
-  - $SETARCH make -s test-spec MSPECOPT=-ff # not using `-j` because sometimes `mspec -j` silently dies
-  - $SETARCH make -s -o showflags leaked-globals
-
-# Branch matrix.  Not all branches are Travis-ready so we limit branches here.
-branches:
-  only:
-    - master
-    - ruby_2_4
-    - ruby_2_5
-    - ruby_2_6
-    - ruby_2_7
-
-# 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:
-    - ko1c-failure@atdot.net
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index ffdf2dd4b8..13df6087ca 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -1,4 +1 @@
-Please see the [official issue tracker] and wiki [HowToContribute].
-
-[official issue tracker]: https://bugs.ruby-lang.org
-[HowToContribute]: https://bugs.ruby-lang.org/projects/ruby/wiki/HowToContribute
+See ["Contributing to Ruby"](https://docs.ruby-lang.org/en/master/contributing_md.html), which includes setup and build instructions.
diff --git a/LEGAL b/LEGAL
index 32bc8a3342..0423d57ac9 100644
--- a/LEGAL
+++ b/LEGAL
@@ -60,6 +60,11 @@ mentioned below.
 
   This file is licensed under the {MIT License}[rdoc-label:label-MIT+License].
 
+[coroutine]
+
+  Unless otherwise specified, these files are licensed under the
+  {MIT License}[rdoc-label:label-MIT+License].
+
 [include/ruby/onigmo.h]
 [include/ruby/oniguruma.h]
 [regcomp.c]
@@ -309,17 +314,6 @@ mentioned below.
     This configure script is free software; the Free Software Foundation
     gives unlimited permission to copy, distribute and modify it.
 
-[aclocal.m4]
-
-  This file is free software.
-
-  >>>
-    Copyright (C) 1996-2020:: Free Software Foundation, Inc.
-
-    This file is free software; the Free Software Foundation
-    gives unlimited permission to copy and/or distribute it,
-    with or without modifications, as long as this notice is preserved.
-
 [tool/config.guess]
 [tool/config.sub]
 
@@ -349,6 +343,34 @@ mentioned below.
     program.  This Exception is an additional permission under section 7
     of the GNU General Public License, version 3 ("GPLv3").
 
+[tool/lib/test/*]
+[tool/lib/core_assertions.rb]
+
+  Some of methods on these files are based on MiniTest 4. MiniTest 4 is
+  distributed under the MIT License.
+
+  >>>
+    Copyright (c) Ryan Davis, seattle.rb
+
+    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.
+
 [parse.c]
 [parse.h]
 
@@ -446,7 +468,8 @@ mentioned below.
 
   >>>
     A C-program for MT19937, with initialization improved 2002/2/10.::
-    Coded by Takuji Nishimura and Makoto Matsumoto.  
+    Coded by Takuji Nishimura and Makoto Matsumoto.
+
     This is a faster version by taking Shawn Cokus's optimization,
     Matthe Bellew's simplification, Isaku Wada's real version.
 
@@ -537,12 +560,8 @@ mentioned below.
 [include/ruby/st.h]
 [missing/acosh.c]
 [missing/alloca.c]
-[missing/dup2.c]
 [missing/erf.c]
-[missing/finite.c]
 [missing/hypot.c]
-[missing/isinf.c]
-[missing/isnan.c]
 [missing/lgamma_r.c]
 [missing/memcmp.c]
 [missing/memmove.c]
@@ -940,9 +959,7 @@ mentioned below.
 
 [lib/bundler]
 [lib/bundler.rb]
-[lib/bundler.gemspec]
 [spec/bundler]
-[man/bundle-*,gemfile.*]
 
   Bundler is under the following license.
 
@@ -952,6 +969,73 @@ mentioned below.
 
     {MIT License}[rdoc-label:label-MIT+License]
 
+[lib/bundler/vendor/thor]
+
+  Thor is under the following license.
+
+  >>>
+    Copyright (c) 2008 Yehuda Katz, Eric Hodel, et al.
+
+    {MIT License}[rdoc-label:label-MIT+License]
+
+[lib/rubygems/resolver/molinillo]
+
+  molinillo is under the following license.
+
+  >>>
+    Copyright (c) 2014 Samuel E. Giddins segiddins@segiddins.me
+
+    {MIT License}[rdoc-label:label-MIT+License]
+
+[lib/bundler/vendor/pub_grub]
+
+  pub_grub is under the following license.
+
+  >>>
+    Copyright (c) 2018 John Hawthorn
+
+    {MIT License}[rdoc-label:label-MIT+License]
+
+[lib/bundler/vendor/connection_pool]
+
+  connection_pool is under the following license.
+
+  >>>
+    Copyright (c) 2011 Mike Perham
+
+    {MIT License}[rdoc-label:label-MIT+License]
+
+[lib/bundler/vendor/net-http-persistent]
+
+  net-http-persistent is under the following license.
+
+  >>>
+    Copyright (c) Eric Hodel, Aaron Patterson
+
+    {MIT License}[rdoc-label:label-MIT+License]
+
+[lib/did_you_mean]
+[lib/did_you_mean.rb]
+[test/did_you_mean]
+
+  did_you_mean is under the following license.
+
+  >>>
+    Copyright (c) 2014-2016 Yuki Nishijima
+
+    {MIT License}[rdoc-label:label-MIT+License]
+
+[lib/error_highlight]
+[lib/error_highlight.rb]
+[test/error_highlight]
+
+  error_highlight is under the following license.
+
+  >>>
+    Copyright (c) 2021 Yusuke Endoh
+
+    {MIT License}[rdoc-label:label-MIT+License]
+
 [benchmark/so_ackermann.rb]
 [benchmark/so_array.rb]
 [benchmark/so_binary_trees.rb]
diff --git a/NEWS.md b/NEWS.md
index 4c9d975078..f6c3c6fc97 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,304 +1,820 @@
-# NEWS for Ruby 2.8.0 (tentative; to be 3.0.0)
+# NEWS for Ruby 3.2.0
 
-This document is a list of user visible feature changes
-since the **2.7.0** release, except for bug fixes.
+This document is a list of user-visible feature changes
+since the **3.1.0** release, except for bug fixes.
 
-Note that each entry is kept so brief that no reason behind or reference
-information is supplied with.  For a full list of changes with all
-sufficient information, see the ChangeLog file or Redmine
-(e.g. `https://bugs.ruby-lang.org/issues/$FEATURE_OR_BUG_NUMBER`).
+Note that each entry is kept to a minimum, see links for details.
 
 ## Language changes
 
-* Keyword arguments are now separated from positional arguments.
-  Code that resulted in deprecation warnings in Ruby 2.7 will now
-  result in ArgumentError or different behavior. [[Feature #14183]]
-
-* Arguments forwarding (`...`) now supports leading arguments.
-  [[Feature #16378]]
+* Anonymous rest and keyword rest arguments can now be passed as
+  arguments, instead of just used in method parameters.
+  [[Feature #18351]]
 
     ```ruby
-    def method_missing(meth, ...)
-      send(:"do_#{meth}", ...)
+    def foo(*)
+      bar(*)
+    end
+    def baz(**)
+      quux(**)
     end
     ```
 
-* Procs accepting a single rest argument and keywords are no longer
-  subject to autosplatting.  This now matches the behavior of Procs
-  accepting a single rest argument and no keywords.
-  [[Feature #16166]]
+* A proc that accepts a single positional argument and keywords will
+  no longer autosplat. [[Bug #18633]]
 
     ```ruby
-    pr = proc{|*a, **kw| [a, kw]}
+    proc{|a, **k| a}.call([1, 2])
+    # Ruby 3.1 and before
+    # => 1
+    # Ruby 3.2 and after
+    # => [1, 2]
+    ```
 
-    pr.call([1])
-    # 2.7 => [[1], {}]
-    # 3.0 => [[[1]], {}]
+* Constant assignment evaluation order for constants set on explicit
+  objects has been made consistent with single attribute assignment
+  evaluation order. With this code:
 
-    pr.call([1, {a: 1}])
-    # 2.7 => [[1], {:a=>1}] # and deprecation warning
-    # 3.0 => [[[1, {:a=>1}]], {}]
+    ```ruby
+    foo::BAR = baz
     ```
 
-* $SAFE is now a normal global variable with no special behavior.
-  C-API methods related to $SAFE have been removed.
-  [[Feature #16131]]
+    `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]]
 
-* yield in singleton class definitions in methods is now a SyntaxError
-  instead of a warning. yield in a class definition outside of a method
-  is now a SyntaxError instead of a LocalJumpError.  [[Feature #15575]]
+* "Find pattern" is no longer experimental.
+  [[Feature #18585]]
 
-* Find pattern is added. [[Feature #16828]]
+* 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
-    case ["a", 1, "b", "c", 2, "d", "e", "f", 3]
-    in [*pre, String => x, String => y, *post]
-      p pre  #=> ["a", 1]
-      p x    #=> "b"
-      p y    #=> "c"
-      p post #=> [2, "d", "e", "f", 3]
+    def target(**kw)
     end
-    ```
 
-* When a class variable is overtaken by the same definition in an
-  ancestor class/module, a RuntimeError is now raised (previously,
-  it only issued a warning in verbose mode.  Additionally, accessing a
-  class variable from the toplevel scope is now a RuntimeError.
-  [[Bug #14541]]
+    # 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
 
-* Rightward assignment statement is added.  [EXPERIMENTAL]
-  [[Feature #15921]]
+    ruby2_keywords def foo(*args)
+      bar(*args)
+    end
 
-    ```ruby
-    fib(10) => x
+    foo(k: 1)
     ```
 
-* Endless method definition is added.  [EXPERIMENTAL]
-  [[Feature #16746]]
+## Core classes updates
 
-    ```ruby
-    def square(x) = x * x
-    ```
+Note: We're only listing outstanding class updates.
+
+* Fiber
+
+    * Introduce Fiber.[] and Fiber.[]= for inheritable fiber storage.
+      Introduce Fiber#storage and Fiber#storage= (experimental) for
+      getting and resetting the current storage.  Introduce
+      `Fiber.new(storage:)` for setting the storage when creating a
+      fiber. [[Feature #19078]]
 
-## Command line options
+        Existing Thread and Fiber local variables can be tricky to use.
+        Thread-local variables are shared between all fibers, making it
+        hard to isolate, while Fiber-local variables can be hard to
+        share.  It is often desirable to define unit of execution
+        ("execution context") such that some state is shared between all
+        fibers and threads created in that context.  This is what Fiber
+        storage provides.
 
-### `--help` option
+        ```ruby
+        def log(message)
+          puts "#{Fiber[:request_id]}: #{message}"
+        end
 
-When the environment variable `RUBY_PAGER` or `PAGER` is present and has
-non-empty value, and the standard input and output are tty, `--help`
-option shows the help message via the pager designated by the value.
-[[Feature #16754]]
+        def handle_requests
+          while request = read_request
+            Fiber.schedule do
+              Fiber[:request_id] = SecureRandom.uuid
 
-## Core classes updates
+              request.messages.each do |message|
+                Fiber.schedule do
+                  log("Handling #{message}") # Log includes inherited request_id.
+                end
+              end
+            end
+          end
+        end
+        ```
 
-Outstanding ones only.
+        You should generally consider Fiber storage for any state which
+        you want to be shared implicitly between all fibers and threads
+        created in a given context, e.g. a connection pool, a request
+        id, a logger level, environment variables, configuration, etc.
 
-* Dir
+* Fiber::Scheduler
 
-    * Modified method
+    * Introduce `Fiber::Scheduler#io_select` for non-blocking IO.select.
+      [[Feature #19060]]
 
-        * Dir.glob and Dir.[] now sort the results by default, and
-          accept `sort:` keyword option.  [[Feature #8709]]
+* IO
 
-* ENV
+    * Introduce IO#timeout= and IO#timeout which can cause
+      IO::TimeoutError to be raised if a blocking operation exceeds the
+      specified timeout. [[Feature #18630]]
 
-    * New method
+        ```ruby
+        STDIN.timeout = 1
+        STDIN.read # => Blocking operation timed out! (IO::TimeoutError)
+        ```
 
-        * ENV.except, which returns a hash excluding the given keys
-          and their values.  [[Feature #15822]]
+    * Introduce `IO.new(..., path:)` and promote `File#path` to `IO#path`.
+      [[Feature #19036]]
 
-* Hash
+* Class
 
-    * Modified method
+    * Class#attached_object, which returns the object for which
+      the receiver is the singleton class. Raises TypeError if the
+      receiver is not a singleton class.
+      [[Feature #12084]]
 
-        * Hash#transform_keys now accepts a hash that maps keys to new
-          keys.  [[Feature #16274]]
+        ```ruby
+        class Foo; end
 
-    * New method
+        Foo.singleton_class.attached_object        #=> Foo
+        Foo.new.singleton_class.attached_object    #=> #<Foo:0x000000010491a370>
+        Foo.attached_object                        #=> TypeError: `Foo' is not a singleton class
+        nil.singleton_class.attached_object        #=> TypeError: `NilClass' is not a singleton class
+        ```
 
-        * Hash#except, which returns a hash excluding the given keys
-          and their values.  [[Feature #15822]]
+* Data
 
-* Kernel
+    * New core class to represent simple immutable value object. The class is
+      similar to Struct and partially shares an implementation, but has more
+      lean and strict API. [[Feature #16122]]
 
-    * Modified method
+        ```ruby
+        Measure = Data.define(:amount, :unit)
+        distance = Measure.new(100, 'km')            #=> #<data Measure amount=100, unit="km">
+        weight = Measure.new(amount: 50, unit: 'kg') #=> #<data Measure amount=50, unit="kg">
+        weight.with(amount: 40)                      #=> #<data Measure amount=40, unit="kg">
+        weight.amount                                #=> 50
+        weight.amount = 40                           #=> NoMethodError: undefined method `amount='
+        ```
 
-        * Kernel#clone when called with `freeze: false` keyword will call
-          #initialize_clone with the `freeze: false` keyword.
-          [[Bug #14266]]
+* Encoding
 
-        * Kernel#clone when called with `freeze: true` keyword will call
-          #initialize_clone with the `freeze: true` keyword, and will
-          return a frozen copy even if the receiver is unfrozen.
-          [[Feature #16175]]
+    * 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]]
+    * Limit maximum encoding set size by 256.
+      If exceeding maximum size, `EncodingError` will be raised. [[Feature #18949]]
+
+* Enumerator
+
+    * Enumerator.product has been added.  Enumerator::Product is the implementation. [[Feature #18685]]
+
+* Exception
+
+    * Exception#detailed_message has been added.
+      The default error printer calls this method on the Exception object
+      instead of #message. [[Feature #18564]]
 
-        * Kernel#eval when called with two arguments will use "(eval)"
-          for `__FILE__` and 1 for `__LINE__` in the evaluated code.
-          [[Bug #4352]]
+* 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]]
+
+* Integer
+
+    * Integer#ceildiv has been added. [[Feature #18809]]
+
+* Kernel
 
-        * Kernel#lambda now warns if called without a literal block.
-          [[Feature #15973]]
+    * Kernel#binding raises RuntimeError if called from a non-Ruby frame
+      (such as a method defined in C). [[Bug #18487]]
+
+* MatchData
+
+    * MatchData#byteoffset has been added. [[Feature #13110]]
+    * MatchData#deconstruct has been added. [[Feature #18821]]
+    * MatchData#deconstruct_keys has been added. [[Feature #18821]]
 
 * Module
 
-    * Modified method
+    * 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]]
 
-        * Module#include and #prepend now affect classes and modules that
-          have already included or prepended the receiver, mirroring the
-          behavior if the arguments were included in the receiver before
-          the other modules and classes included or prepended the receiver.
-          [[Feature #9573]]
+* Proc
 
-* Symbol
+    * Proc#dup returns an instance of subclass. [[Bug #17545]]
+    * Proc#parameters now accepts lambda keyword. [[Feature #15357]]
 
-    * Modified method
+* Process
+    * Added `RLIMIT_NPTS` constant to FreeBSD platform
 
-        * Symbol#to_proc now returns a lambda Proc.
-          [[Feature #16260]]
+* Regexp
 
-## Stdlib updates
+    * The cache-based optimization is introduced.
+      Many (but not all) Regexp matching is now in linear time, which
+      will prevent regular expression denial of service (ReDoS)
+      vulnerability. [[Feature #19104]]
 
-Outstanding ones only.
+    * Regexp.linear_time? is introduced. [[Feature #19194]]
 
-* RubyGems
+    * Regexp.new now supports passing the regexp flags not only as an Integer,
+      but also as a String.  Unknown flags raise ArgumentError.
+      Otherwise, anything other than `true`, `false`, `nil` or Integer will be warned.
+      [[Feature #18788]]
 
-    * Update to RubyGems 3.2.0.pre1
+    * Regexp.timeout= has been added. Also, Regexp.new new supports timeout keyword.
+      See [[Feature #17837]]
 
-* Bundler
+* Refinement
 
-    * Update to Bundler 2.2.0.dev
+    * Refinement#refined_class has been added. [[Feature #12737]]
 
-* Net::HTTP
+* RubyVM::AbstractSyntaxTree
 
-    * New method
+    * Add `error_tolerant` option for `parse`, `parse_file` and `of`. [[Feature #19013]]
+      With this option
 
-        * Add Net::HTTP#verify_hostname= and Net::HTTP#verify_hostname
-          to skip hostname verification.  [[Feature #16555]]
+        1. SyntaxError is suppressed
+        2. AST is returned for invalid input
+        3. `end` is complemented when a parser reaches to the end of input but `end` is insufficient
+        4. `end` is treated as keyword based on indent
 
-    * Modified method
+        ```ruby
+        # Without error_tolerant option
+        root = RubyVM::AbstractSyntaxTree.parse(<<~RUBY)
+        def m
+          a = 10
+          if
+        end
+        RUBY
+        # => <internal:ast>:33:in `parse': syntax error, unexpected `end' (SyntaxError)
 
-        * Net::HTTP.get, Net::HTTP.get_response, and Net::HTTP.get_print can
-          take request headers as a Hash in the second argument when the first
-          argument is a URI.
+        # With error_tolerant option
+        root = RubyVM::AbstractSyntaxTree.parse(<<~RUBY, error_tolerant: true)
+        def m
+          a = 10
+          if
+        end
+        RUBY
+        p root # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-4:3>
 
-## Compatibility issues
+        # `end` is treated as keyword based on indent
+        root = RubyVM::AbstractSyntaxTree.parse(<<~RUBY, error_tolerant: true)
+        module Z
+          class Foo
+            foo.
+          end
 
-Excluding feature bug fixes.
+          def bar
+          end
+        end
+        RUBY
+        p root.children[-1].children[-1].children[-1].children[-2..-1]
+        # => [#<RubyVM::AbstractSyntaxTree::Node:CLASS@2:2-4:5>, #<RubyVM::AbstractSyntaxTree::Node:DEFN@6:2-7:5>]
+        ```
 
-* Regexp literals are frozen [[Feature #8948]] [[Feature #16377]]
+    * Add `keep_tokens` option for `parse`, `parse_file` and `of`. Add `#tokens` and `#all_tokens`
+      for RubyVM::AbstractSyntaxTree::Node [[Feature #19070]]
 
-    ```ruby
-    /foo/.frozen? #=> true
-    ```
+        ```ruby
+        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"
+        ```
 
-* Bundled gems
+* Set
 
-    * net-telnet and xmlrpc have been removed from the bundled gems.
-      If you are interested in maintaining them, please comment on
-      your plan to https://github.com/ruby/xmlrpc
-      or https://github.com/ruby/net-telnet.
+    * 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.
 
-* EXPERIMENTAL: Hash#each consistently yields a 2-element array [[Bug #12706]]
+* String
 
-    * Now `{ a: 1 }.each(&->(k, v) { })` raises an ArgumentError
-      due to lambda's arity check.
-    * This is experimental; if it brings a big incompatibility issue,
-      it may be reverted until 2.8/3.0 release.
+    * String#byteindex and String#byterindex have been added. [[Feature #13110]]
+    * Update Unicode to Version 15.0.0 and Emoji Version 15.0. [[Feature #18639]]
+      (also applies to Regexp)
+    * String#bytesplice has been added.  [[Feature #18598]]
+    * String#dedup has been added as an alias to String#-@.  [[Feature #18595]]
 
-* When writing to STDOUT redirected to a closed pipe, no broken pipe
-  error message will be shown now.  [[Feature #14413]]
+* Struct
 
-* `TRUE`/`FALSE`/`NIL` constants are no longer defined.
+    * A Struct class can also be initialized with keyword arguments
+      without `keyword_init: true` on Struct.new [[Feature #16806]]
 
-* SDBM have been removed from ruby standard library.
+        ```ruby
+        Post = Struct.new(:id, :name)
+        Post.new(1, "hello") #=> #<struct Post id=1, name="hello">
+        # From Ruby 3.2, the following code also works without keyword_init: true.
+        Post.new(id: 1, name: "hello") #=> #<struct Post id=1, name="hello">
+        ```
 
-    * The issues of sdbm will handle at https://github.com/ruby/sdbm
+* Thread
 
-* `Integer#zero?` overrides `Numeric#zero?` for optimization.
+    * Thread.each_caller_location is added. [[Feature #16663]]
 
-## Stdlib compatibility issues
+* Thread::Queue
 
-Excluding feature bug fixes.
+    * Thread::Queue#pop(timeout: sec) is added. [[Feature #18774]]
 
-## C API updates
+* Thread::SizedQueue
+
+    * Thread::SizedQueue#pop(timeout: sec) is added. [[Feature #18774]]
+    * Thread::SizedQueue#push(timeout: sec) is added. [[Feature #18944]]
+
+* Time
+
+    * Time#deconstruct_keys is added, allowing to use Time instances
+      in pattern-matching expressions [[Feature #19071]]
+
+    * Time.new now can parse a string like generated by Time#inspect
+      and return a Time instance based on the given argument.
+      [[Feature #18033]]
+
+* SyntaxError
+    * SyntaxError#path has been added.  [[Feature #19138]]
 
-* C API functions related to $SAFE have been removed.
+* 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 a block is given and `target` and `target_line` keyword
+      arguments are not passed. [[Bug #16889]]
+
+* UnboundMethod
+
+    * `UnboundMethod#==` returns `true` if the actual method is same. For example,
+      `String.instance_method(:object_id) == Array.instance_method(:object_id)`
+      returns `true`. [[Feature #18798]]
+
+    * `UnboundMethod#inspect` does not show the receiver of `instance_method`.
+      For example `String.instance_method(:object_id).inspect` returns
+      `"#<UnboundMethod: Kernel#object_id()>"`
+      (was `"#<UnboundMethod: String(Kernel)#object_id()>"`).
+
+* GC
+
+    * Expose `need_major_gc` via `GC.latest_gc_info`. [GH-6791]
+
+* ObjectSpace
+
+    * `ObjectSpace.dump_all` dump shapes as well. [GH-6868]
+
+## Stdlib updates
+
+* Bundler
+
+    * Bundler now uses [PubGrub] resolver instead of [Molinillo] for performance improvement.
+    * Add --ext=rust support to bundle gem for creating simple gems with Rust extensions.
+      [[GH-rubygems-6149]]
+    * Make cloning git repos faster [[GH-rubygems-4475]]
+
+* RubyGems
+
+    * Add mswin support for cargo builder. [[GH-rubygems-6167]]
+
+* CGI
+
+    * `CGI.escapeURIComponent` and `CGI.unescapeURIComponent` are added.
+      [[Feature #18822]]
+
+* Coverage
+
+    * `Coverage.setup` now accepts `eval: true`. By this, `eval` and related methods are
+      able to generate code coverage. [[Feature #19008]]
+
+    * `Coverage.supported?(mode)` enables detection of what coverage modes are
+      supported. [[Feature #19026]]
+
+* Date
+
+    * Added `Date#deconstruct_keys` and `DateTime#deconstruct_keys` same as [[Feature #19071]]
+
+* ERB
+
+    * `ERB::Util.html_escape` is made faster than `CGI.escapeHTML`.
+        * It no longer allocates a String object when no character needs to be escaped.
+        * It skips calling `#to_s` method when an argument is already a String.
+        * `ERB::Escape.html_escape` is added as an alias to `ERB::Util.html_escape`,
+          which has not been monkey-patched by Rails.
+    * `ERB::Util.url_encode` is made faster using `CGI.escapeURIComponent`.
+    * `-S` option is removed from `erb` command.
+
+* FileUtils
+
+    * Add FileUtils.ln_sr method and `relative:` option to FileUtils.ln_s.
+      [[Feature #18925]]
+
+* IRB
+
+    * debug.gem integration commands have been added: `debug`, `break`, `catch`,
+      `next`, `delete`, `step`, `continue`, `finish`, `backtrace`, `info`
+        * They work even if you don't have `gem "debug"` in your Gemfile.
+        * See also: [What's new in Ruby 3.2's IRB?](https://st0012.dev/whats-new-in-ruby-3-2-irb)
+    * More Pry-like commands and features have been added.
+        * `edit` and `show_cmds` (like Pry's `help`) are added.
+        * `ls` takes `-g` or `-G` option to filter out outputs.
+        * `show_source` is aliased from `$` and accepts unquoted inputs.
+        * `whereami` is aliased from `@`.
+
+* Net::Protocol
+
+    * Improve `Net::BufferedIO` performance. [[GH-net-protocol-14]]
+
+* Pathname
+
+    * Added `Pathname#lutime`. [[GH-pathname-20]]
+
+* Socket
+
+    * Added the following constants for supported platforms.
+        * `SO_INCOMING_CPU`
+        * `SO_INCOMING_NAPI_ID`
+        * `SO_RTABLE`
+        * `SO_SETFIB`
+        * `SO_USER_COOKIE`
+        * `TCP_KEEPALIVE`
+        * `TCP_CONNECTION_INFO`
+
+* SyntaxSuggest
+
+    * The feature of `syntax_suggest` formerly `dead_end` is integrated in Ruby.
+      [[Feature #18159]]
+
+* UNIXSocket
+
+    * Add support for UNIXSocket on Windows. Emulate anonymous sockets. Add
+      support for File.socket? and File::Stat#socket? where possible.
+      [[Feature #19135]]
+
+*   The following default gems are updated.
+
+    * RubyGems 3.4.1
+    * abbrev 0.1.1
+    * benchmark 0.2.1
+    * bigdecimal 3.1.3
+    * bundler 2.4.1
+    * cgi 0.3.6
+    * csv 3.2.6
+    * date 3.3.3
+    * delegate 0.3.0
+    * did_you_mean 1.6.3
+    * digest 3.1.1
+    * drb 2.1.1
+    * english 0.7.2
+    * erb 4.0.2
+    * error_highlight 0.5.1
+    * etc 1.4.2
+    * fcntl 1.0.2
+    * fiddle 1.1.1
+    * fileutils 1.7.0
+    * forwardable 1.3.3
+    * getoptlong 0.2.0
+    * io-console 0.6.0
+    * io-nonblock 0.2.0
+    * io-wait 0.3.0
+    * ipaddr 1.2.5
+    * irb 1.6.2
+    * json 2.6.3
+    * logger 1.5.3
+    * mutex_m 0.1.2
+    * net-http 0.4.0
+    * net-protocol 0.2.1
+    * nkf 0.1.2
+    * open-uri 0.3.0
+    * open3 0.1.2
+    * openssl 3.1.0
+    * optparse 0.3.1
+    * ostruct 0.5.5
+    * pathname 0.2.1
+    * pp 0.4.0
+    * pstore 0.1.2
+    * psych 5.0.1
+    * racc 1.6.2
+    * rdoc 6.5.0
+    * readline-ext 0.1.5
+    * reline 0.3.2
+    * resolv 0.2.2
+    * resolv-replace 0.1.1
+    * securerandom 0.2.2
+    * set 1.0.3
+    * stringio 3.0.4
+    * strscan 3.0.5
+    * syntax_suggest 1.0.2
+    * syslog 0.1.1
+    * tempfile 0.1.3
+    * time 0.2.1
+    * timeout 0.3.1
+    * tmpdir 0.1.3
+    * tsort 0.1.1
+    * un 0.2.1
+    * uri 0.12.0
+    * weakref 0.1.2
+    * win32ole 1.8.9
+    * yaml 0.2.1
+    * zlib 3.0.0
+
+*   The following bundled gems are updated.
+
+    * minitest 5.16.3
+    * power_assert 2.0.3
+    * test-unit 3.5.7
+    * net-ftp 0.2.0
+    * net-imap 0.3.4
+    * net-pop 0.1.2
+    * net-smtp 0.3.3
+    * rbs 2.8.2
+    * typeprof 0.21.3
+    * debug 1.7.1
+
+See GitHub releases like [GitHub Releases of Logger](https://github.com/ruby/logger/releases) or changelog for details of the default gems or bundled gems.
+
+## Supported platforms
+
+* WebAssembly/WASI is added. See [wasm/README.md] and [ruby.wasm] for more details. [[Feature #18462]]
+
+## Compatibility issues
+
+* `String#to_c` currently treat a sequence of underscores as an end of Complex
+  string. [[Bug #19087]]
+
+* Now `ENV.clone` raises `TypeError` as well as `ENV.dup` [[Bug #17767]]
+
+### Removed constants
+
+The following deprecated constants are removed.
+
+* `Fixnum` and `Bignum` [[Feature #12005]]
+* `Random::DEFAULT` [[Feature #17351]]
+* `Struct::Group`
+* `Struct::Passwd`
+
+### Removed methods
+
+The following deprecated methods are removed.
+
+* `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]]
+* `Method#public?`, `Method#private?`, `Method#protected?`,
+  `UnboundMethod#public?`, `UnboundMethod#private?`, `UnboundMethod#protected?`
+  [[Bug #18729]] [[Bug #18751]] [[Bug #18435]]
 
-* C API header file `ruby/ruby.h` was split. [[GH-2991]] Should have no impact
-  on extension libraries, but users might experience slow compilations.
+### Source code incompatibility of extension libraries
 
-## Implementation improvements
+* Extension libraries provide PRNG, subclasses of Random, need updates.
+  See [PRNG update] below for more information. [[Bug #19100]]
+
+### Error printer
 
-* New method cache mechanism for Ractor [[Feature #16614]]
+* Ruby no longer escapes control characters and backslashes in an
+  error message. [[Feature #18367]]
 
-  * TODO: ko1 will write details
+### Constant lookup when defining a class/module
 
-* The number of hashes allocated when using a keyword splat in
-  a method call has been reduced to a maximum of 1, and passing
-  a keyword splat to a method that accepts specific keywords
-  does not allocate a hash.
+* When defining a class/module directly under the Object class by class/module
+  statement, if there is already a class/module defined by `Module#include`
+  with the same name, the statement was handled as "open class" in Ruby 3.1 or before.
+  Since Ruby 3.2, a new class is defined instead. [[Feature #18832]]
 
-* `super` is optimized when the same type of method is called in the previous call
-  if it's not refinements or an attr reader or writer.
+## Stdlib compatibility issues
+
+* Psych no longer bundles libyaml sources.
+  And also Fiddle no longer bundles libffi sources.
+  Users need to install the libyaml/libffi library themselves via the package
+  manager like apt, yum, brew, etc.
+
+    Psych and fiddle supported the static build with specific version of libyaml
+    and libffi sources. You can build psych with libyaml-0.2.5 like this.
+
+    ```bash
+    $ ./configure --with-libyaml-source-dir=/path/to/libyaml-0.2.5
+    ```
 
-### JIT
+    And you can build fiddle with libffi-3.4.4 like this.
 
-* Native functions shared by multiple methods are deduplicated on JIT compaction.
+    ```bash
+    $ ./configure --with-libffi-source-dir=/path/to/libffi-3.4.4
+    ```
+
+    [[Feature #18571]]
 
-* Decrease code size of hot paths by some optimizations and partitioning cold paths.
+* Check cookie name/path/domain characters in `CGI::Cookie`. [[CVE-2021-33621]]
 
-* Not only pure Ruby methods but also some C methods skip pushing a method frame.
+* `URI.parse` return empty string in host instead of nil. [[sec-156615]]
 
-  * `Kernel#class`, `Integer#zero?`
+## C API updates
 
-* Always generate appropriate code for `==`, `nil?`, and `!` calls depending on
-  a receiver class.
+### Updated C APIs
 
-* Optimize instance variable access in some core classes like Hash and their subclasses
+The following APIs are updated.
 
-* Eliminate VM register access on a method return
+* PRNG update
 
-* Optimize C method call a little
+    `rb_random_interface_t` in ruby/random.h updated and versioned.
+    Extension libraries which use this interface and built for older
+    versions need to rebuild with adding `init_int32` function.
 
-## Miscellaneous changes
+### Added C APIs
 
-* Methods using `ruby2_keywords` will no longer keep empty keyword
-  splats, those are now removed just as they are for methods not
-  using `ruby2_keywords`.
+* `VALUE rb_hash_new_capa(long capa)` was added to created hashes with the desired capacity.
+* `rb_internal_thread_add_event_hook` and `rb_internal_thread_add_event_hook` were added to instrument threads scheduling.
+  The following events are available:
+    * `RUBY_INTERNAL_THREAD_EVENT_STARTED`
+    * `RUBY_INTERNAL_THREAD_EVENT_READY`
+    * `RUBY_INTERNAL_THREAD_EVENT_RESUMED`
+    * `RUBY_INTERNAL_THREAD_EVENT_SUSPENDED`
+    * `RUBY_INTERNAL_THREAD_EVENT_EXITED`
+* `rb_debug_inspector_current_depth` and `rb_debug_inspector_frame_depth` are added for debuggers.
 
-* Taint deprecation warnings are now issued in regular mode in
-  addition to verbose warning mode.  [[Feature #16131]]
+### Removed C APIs
 
-* When an exception is caught in the default handler, the error
-  message and backtrace are printed in order from the innermost.
-  [[Feature #8661]]
+The following deprecated APIs are removed.
 
+* `rb_cData` variable.
+* "taintedness" and "trustedness" functions. [[Feature #16131]]
+
+## Implementation improvements
 
-[Bug #4352]:      https://bugs.ruby-lang.org/issues/4352
-[Feature #8661]:  https://bugs.ruby-lang.org/issues/8661
-[Feature #8709]:  https://bugs.ruby-lang.org/issues/8709
-[Feature #8948]:  https://bugs.ruby-lang.org/issues/8948
-[Feature #9573]:  https://bugs.ruby-lang.org/issues/9573
-[Feature #14183]: https://bugs.ruby-lang.org/issues/14183
-[Bug #14266]:     https://bugs.ruby-lang.org/issues/14266
-[Feature #14413]: https://bugs.ruby-lang.org/issues/14413
-[Feature #15575]: https://bugs.ruby-lang.org/issues/15575
-[Feature #16131]: https://bugs.ruby-lang.org/issues/16131
-[Feature #16166]: https://bugs.ruby-lang.org/issues/16166
-[Feature #16260]: https://bugs.ruby-lang.org/issues/16260
-[Feature #16274]: https://bugs.ruby-lang.org/issues/16274
-[Feature #16377]: https://bugs.ruby-lang.org/issues/16377
-[Bug #12706]:     https://bugs.ruby-lang.org/issues/12706
-[Feature #15921]: https://bugs.ruby-lang.org/issues/15921
-[Feature #16555]: https://bugs.ruby-lang.org/issues/16555
-[Feature #16746]: https://bugs.ruby-lang.org/issues/16746
-[Feature #16754]: https://bugs.ruby-lang.org/issues/16754
-[GH-2991]:        https://github.com/ruby/ruby/pull/2991
-[Feature #15822]: https://bugs.ruby-lang.org/issues/15822
-[Feature #16378]: https://bugs.ruby-lang.org/issues/16378
-[Feature #16828]: https://bugs.ruby-lang.org/issues/16828
-[Bug #14541]:     https://bugs.ruby-lang.org/issues/14541
-[Feature #16175]: https://bugs.ruby-lang.org/issues/16175
-[Feature #15973]: https://bugs.ruby-lang.org/issues/15973
-[Feature #16614]: https://bugs.ruby-lang.org/issues/16614
+* Fixed several race conditions in Kernel#autoload. [[Bug #18782]]
+* Cache invalidation for expressions referencing constants is now
+  more fine-grained. `RubyVM.stat(:global_constant_state)` was
+  removed because it was closely tied to the previous caching scheme
+  where setting any constant invalidates all caches in the system.
+  New keys, `:constant_cache_invalidations` and `:constant_cache_misses`,
+  were introduced to help with use cases for `:global_constant_state`.
+  [[Feature #18589]]
+* The cache-based optimization for Regexp matching is introduced.
+  [[Feature #19104]]
+* [Variable Width Allocation](https://shopify.engineering/ruby-variable-width-allocation)
+  is now enabled by default. [[Feature #18239]]
+* Added a new instance variable caching mechanism, called object shapes, which
+  improves inline cache hits for most objects and allows us to generate very
+  efficient JIT code. Objects whose instance variables are defined in a
+  consistent order will see the most performance benefits.
+  [[Feature #18776]]
+* Speed up marking instruction sequences by using a bitmap to find "markable"
+  objects.  This change results in faster major collections.
+  [[Feature #18875]]
+
+## JIT
+
+### YJIT
+
+* YJIT is no longer experimental
+    * Has been tested on production workloads for over a year and proven to be quite stable.
+* YJIT now supports both x86-64 and arm64/aarch64 CPUs on Linux, MacOS, BSD and other UNIX platforms.
+    * This release brings support for Mac M1/M2, AWS Graviton and Raspberry Pi 4.
+* Building YJIT now requires Rust 1.58.0+. [[Feature #18481]]
+    * In order to ensure that CRuby is built with YJIT, please install `rustc` >= 1.58.0
+      before running `./configure`
+    * Please reach out to the YJIT team should you run into any issues.
+* Physical memory for JIT code is lazily allocated. Unlike Ruby 3.1,
+  the RSS of a Ruby process is minimized because virtual memory pages
+  allocated by `--yjit-exec-mem-size` will not be mapped to physical
+  memory pages until actually utilized by JIT code.
+* Introduce Code GC that frees all code pages when the memory consumption
+  by JIT code reaches `--yjit-exec-mem-size`.
+    * `RubyVM::YJIT.runtime_stats` returns Code GC metrics in addition to
+      existing `inline_code_size` and `outlined_code_size` keys:
+      `code_gc_count`, `live_page_count`, `freed_page_count`, and `freed_code_size`.
+* Most of the statistics produced by `RubyVM::YJIT.runtime_stats` are now available in release builds.
+    * Simply run ruby with `--yjit-stats` to compute and dump stats (incurs some run-time overhead).
+* YJIT is now optimized to take advantage of object shapes. [[Feature #18776]]
+* Take advantage of finer-grained constant invalidation to invalidate less code when defining new constants. [[Feature #18589]]
+* The default `--yjit-exec-mem-size` is changed to 64 (MiB).
+* The default `--yjit-call-threshold` is changed to 30.
+
+### MJIT
+
+* The MJIT compiler is re-implemented in Ruby as `ruby_vm/mjit/compiler`.
+* MJIT compiler is executed under a forked Ruby process instead of
+  doing it in a native thread called MJIT worker. [[Feature #18968]]
+    * As a result, Microsoft Visual Studio (MSWIN) is no longer supported.
+* MinGW is no longer supported. [[Feature #18824]]
+* Rename `--mjit-min-calls` to `--mjit-call-threshold`.
+* Change default `--mjit-max-cache` back from 10000 to 100.
+
+[Feature #12005]:     https://bugs.ruby-lang.org/issues/12005
+[Feature #12084]:     https://bugs.ruby-lang.org/issues/12084
+[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 #16122]:     https://bugs.ruby-lang.org/issues/16122
+[Feature #16131]:     https://bugs.ruby-lang.org/issues/16131
+[Bug #16466]:         https://bugs.ruby-lang.org/issues/16466
+[Feature #16663]:     https://bugs.ruby-lang.org/issues/16663
+[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
+[Bug #17767]:         https://bugs.ruby-lang.org/issues/17767
+[Feature #17837]:     https://bugs.ruby-lang.org/issues/17837
+[Feature #17881]:     https://bugs.ruby-lang.org/issues/17881
+[Feature #18033]:     https://bugs.ruby-lang.org/issues/18033
+[Feature #18159]:     https://bugs.ruby-lang.org/issues/18159
+[Feature #18239]:     https://bugs.ruby-lang.org/issues/18239#note-17
+[Feature #18351]:     https://bugs.ruby-lang.org/issues/18351
+[Feature #18367]:     https://bugs.ruby-lang.org/issues/18367
+[Bug #18435]:         https://bugs.ruby-lang.org/issues/18435
+[Feature #18462]:     https://bugs.ruby-lang.org/issues/18462
+[Feature #18481]:     https://bugs.ruby-lang.org/issues/18481
+[Bug #18487]:         https://bugs.ruby-lang.org/issues/18487
+[Feature #18564]:     https://bugs.ruby-lang.org/issues/18564
+[Feature #18571]:     https://bugs.ruby-lang.org/issues/18571
+[Feature #18585]:     https://bugs.ruby-lang.org/issues/18585
+[Feature #18589]:     https://bugs.ruby-lang.org/issues/18589
+[Feature #18595]:     https://bugs.ruby-lang.org/issues/18595
+[Feature #18598]:     https://bugs.ruby-lang.org/issues/18598
+[Bug #18625]:         https://bugs.ruby-lang.org/issues/18625
+[Feature #18630]:     https://bugs.ruby-lang.org/issues/18630
+[Bug #18633]:         https://bugs.ruby-lang.org/issues/18633
+[Feature #18639]:     https://bugs.ruby-lang.org/issues/18639
+[Feature #18685]:     https://bugs.ruby-lang.org/issues/18685
+[Bug #18729]:         https://bugs.ruby-lang.org/issues/18729
+[Bug #18751]:         https://bugs.ruby-lang.org/issues/18751
+[Feature #18774]:     https://bugs.ruby-lang.org/issues/18774
+[Feature #18776]:     https://bugs.ruby-lang.org/issues/18776
+[Bug #18782]:         https://bugs.ruby-lang.org/issues/18782
+[Feature #18788]:     https://bugs.ruby-lang.org/issues/18788
+[Feature #18798]:     https://bugs.ruby-lang.org/issues/18798
+[Feature #18809]:     https://bugs.ruby-lang.org/issues/18809
+[Feature #18821]:     https://bugs.ruby-lang.org/issues/18821
+[Feature #18822]:     https://bugs.ruby-lang.org/issues/18822
+[Feature #18824]:     https://bugs.ruby-lang.org/issues/18824
+[Feature #18832]:     https://bugs.ruby-lang.org/issues/18832
+[Feature #18875]:     https://bugs.ruby-lang.org/issues/18875
+[Feature #18925]:     https://bugs.ruby-lang.org/issues/18925
+[Feature #18944]:     https://bugs.ruby-lang.org/issues/18944
+[Feature #18949]:     https://bugs.ruby-lang.org/issues/18949
+[Feature #18968]:     https://bugs.ruby-lang.org/issues/18968
+[Feature #19008]:     https://bugs.ruby-lang.org/issues/19008
+[Feature #19013]:     https://bugs.ruby-lang.org/issues/19013
+[Feature #19026]:     https://bugs.ruby-lang.org/issues/19026
+[Feature #19036]:     https://bugs.ruby-lang.org/issues/19036
+[Feature #19060]:     https://bugs.ruby-lang.org/issues/19060
+[Feature #19070]:     https://bugs.ruby-lang.org/issues/19070
+[Feature #19071]:     https://bugs.ruby-lang.org/issues/19071
+[Feature #19078]:     https://bugs.ruby-lang.org/issues/19078
+[Bug #19087]:         https://bugs.ruby-lang.org/issues/19087
+[Bug #19100]:         https://bugs.ruby-lang.org/issues/19100
+[Feature #19104]:     https://bugs.ruby-lang.org/issues/19104
+[Feature #19135]:     https://bugs.ruby-lang.org/issues/19135
+[Feature #19138]:     https://bugs.ruby-lang.org/issues/19138
+[Feature #19194]:     https://bugs.ruby-lang.org/issues/19194
+[Molinillo]:          https://github.com/CocoaPods/Molinillo
+[PubGrub]:            https://github.com/jhawthorn/pub_grub
+[GH-net-protocol-14]: https://github.com/ruby/net-protocol/pull/14
+[GH-pathname-20]:     https://github.com/ruby/pathname/pull/20
+[GH-6791]:            https://github.com/ruby/ruby/pull/6791
+[GH-6868]:            https://github.com/ruby/ruby/pull/6868
+[GH-rubygems-4475]:   https://github.com/rubygems/rubygems/pull/4475
+[GH-rubygems-6149]:   https://github.com/rubygems/rubygems/pull/6149
+[GH-rubygems-6167]:   https://github.com/rubygems/rubygems/pull/6167
+[sec-156615]:         https://hackerone.com/reports/156615
+[CVE-2021-33621]:     https://www.ruby-lang.org/en/news/2022/11/22/http-response-splitting-in-cgi-cve-2021-33621/
+[wasm/README.md]:     https://github.com/ruby/ruby/blob/master/wasm/README.md
+[ruby.wasm]:          https://github.com/ruby/ruby.wasm
diff --git a/README.ja.md b/README.ja.md
index bee6433c62..93c0131690 100644
--- a/README.ja.md
+++ b/README.ja.md
@@ -1,10 +1,9 @@
-[![Build Status](https://travis-ci.org/ruby/ruby.svg?branch=master)](https://travis-ci.org/ruby/ruby)
-[![Build status](https://ci.appveyor.com/api/projects/status/0sy8rrxut4o0k960/branch/master?svg=true)](https://ci.appveyor.com/project/ruby/ruby/branch/master)
-[![Actions Status](https://github.com/ruby/ruby/workflows/macOS/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"macOS")
-[![Actions Status](https://github.com/ruby/ruby/workflows/MinGW/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"MinGW")
-[![Actions Status](https://github.com/ruby/ruby/workflows/MJIT/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"MJIT")
-[![Actions Status](https://github.com/ruby/ruby/workflows/Ubuntu/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Ubuntu")
-[![Actions Status](https://github.com/ruby/ruby/workflows/Windows/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Windows")
+[![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)
 
 # Rubyとは
 
@@ -52,11 +51,11 @@ Rubyリポジトリの本来のmasterは https://git.ruby-lang.org/ruby.git に�
 
 ### 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取得できます．
+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
 
-他に開発中のブランチの一覧は次のコマンドで見られます．
+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/
 
@@ -71,31 +70,26 @@ 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
-
-mailto: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@ruby-lang.org] まで本文に
 
     subscribe
 
 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
-
-mailto: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．
+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．
 
 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
+
 ## コンパイル・インストール
 
 以下の手順で行ってください．
 
-1.  もし `configure` ファイルが見つからない，もしくは `configure.ac` より古いようなら， `autoconf` を実行して
-    新しく `configure` を生成する
+1.  (Gitリポジトリから取得したソースをビルドする場合) `./autogen.sh` を実行して新しく `configure` を生成する
 
 2.  `configure` を実行して `Makefile` などを生成する
 
@@ -172,11 +166,14 @@ UNIXであれば `configure` がほとんどの差異を吸収してくれるは
 
 ## フィードバック
 
-Rubyに関する質問は Ruby-Talk（英語）や Ruby-List（日本語） (https://www.ruby-lang.org/ja/community/mailing-lists) や，
-stackoverflow (https://ja.stackoverflow.com/) などのWebサイトに投稿してください．
+Rubyに関する質問は [Ruby-Talk]（英語）や [Ruby-List]（日本語）や，
+[stackoverflow] などのWebサイトに投稿してください．
 
 バグ報告は https://bugs.ruby-lang.org で受け付けています．
 
+[Ruby-Talk]: https://www.ruby-lang.org/en/community/mailing-lists
+[Ruby-List]: https://www.ruby-lang.org/ja/community/mailing-lists
+[stackoverflow]: https://ja.stackoverflow.com/
 
 ## 著者
 
diff --git a/README.md b/README.md
index f06bf1d3ea..c445448c71 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,11 @@
-[![Build Status](https://travis-ci.org/ruby/ruby.svg?branch=master)](https://travis-ci.org/ruby/ruby)
-[![Build status](https://ci.appveyor.com/api/projects/status/0sy8rrxut4o0k960/branch/master?svg=true)](https://ci.appveyor.com/project/ruby/ruby/branch/master)
-[![Actions Status](https://github.com/ruby/ruby/workflows/macOS/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"macOS")
-[![Actions Status](https://github.com/ruby/ruby/workflows/MinGW/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"MinGW")
-[![Actions Status](https://github.com/ruby/ruby/workflows/MJIT/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"MJIT")
-[![Actions Status](https://github.com/ruby/ruby/workflows/Ubuntu/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Ubuntu")
-[![Actions Status](https://github.com/ruby/ruby/workflows/Windows/badge.svg)](https://github.com/ruby/ruby/actions?query=workflow%3A"Windows")
+[![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)
 
-# What's Ruby
+# What is Ruby?
 
 Ruby is an interpreted object-oriented programming language often
 used for web development. It also offers many scripting features
@@ -15,28 +14,25 @@ It is simple, straightforward, and extensible.
 
 ## Features of Ruby
 
-*   Simple Syntax
-*   **Normal** Object-oriented Features (e.g. class, method calls)
-*   **Advanced** Object-oriented Features (e.g. mix-in, singleton-method)
-*   Operator Overloading
-*   Exception Handling
-*   Iterators and Closures
-*   Garbage Collection
-*   Dynamic Loading of Object Files (on some architectures)
-*   Highly Portable (works on many Unix-like/POSIX compatible platforms as
-    well as Windows, macOS, Haiku, etc.) cf.
-    https://github.com/ruby/ruby/blob/master/doc/contributing.rdoc#platform-maintainers
+* Simple Syntax
+* **Normal** Object-oriented Features (e.g. class, method calls)
+* **Advanced** Object-oriented Features (e.g. mix-in, singleton-method)
+* Operator Overloading
+* Exception Handling
+* Iterators and Closures
+* Garbage Collection
+* 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
 
-
-## How to get Ruby
+## How to get Ruby with Git
 
 For a complete list of ways to install Ruby, including using third-party tools
 like rvm, see:
 
 https://www.ruby-lang.org/en/downloads/
 
-### Git
-
 The mirror of the Ruby source tree can be checked out with the following command:
 
     $ git clone https://github.com/ruby/ruby.git
@@ -49,21 +45,19 @@ to see the list of branches:
 You may also want to use https://git.ruby-lang.org/ruby.git (actual master of Ruby source)
 if you are a committer.
 
-### Subversion
-
-Stable branches for older Ruby versions can be checked out with the following command:
-
-    $ svn co https://svn.ruby-lang.org/repos/ruby/branches/ruby_2_6/ ruby
-
-Try the following command to see the list of branches:
-
-    $ svn ls https://svn.ruby-lang.org/repos/ruby/branches/
+## How to build
 
+see [Building Ruby](doc/contributing/building_ruby.md)
 
 ## Ruby home page
 
 https://www.ruby-lang.org/
 
+## Documentation
+
+- [English](https://docs.ruby-lang.org/en/master/index.html)
+- [Japanese](https://docs.ruby-lang.org/ja/master/index.html)
+
 ## Mailing list
 
 There is a mailing list to discuss Ruby. To subscribe to this list, please
@@ -71,98 +65,24 @@ send the following phrase:
 
     subscribe
 
-in the mail body (not subject) to the address
-[ruby-talk-request@ruby-lang.org](mailto:ruby-talk-request@ruby-lang.org?subject=Join%20Ruby%20Mailing%20List&body=subscribe).
-
-## How to compile and install
-
-1.  If you want to use Microsoft Visual C++ to compile Ruby, read
-    [win32/README.win32](win32/README.win32) instead of this document.
-
-2.  If `./configure` does not exist or is older than `configure.ac`, run
-    `autoconf` to (re)generate configure.
-
-3.  Run `./configure`, which will generate `config.h` and `Makefile`.
-
-    Some C compiler flags may be added by default depending on your
-    environment. Specify `optflags=..` and `warnflags=..` as necessary to
-    override them.
-
-4.  Edit `include/ruby/defines.h` if you need. Usually this step will not be needed.
-
-5.  Remove comment mark(`#`) before the module names from `ext/Setup` (or add
-    module names if not present), if you want to link modules statically.
+in the mail body (not subject) to the address [ruby-talk-request@ruby-lang.org].
 
-    If you don't want to compile non static extension modules (probably on
-    architectures which do not allow dynamic loading), remove comment mark
-    from the line "`#option nodynamic`" in `ext/Setup`.
-
-    Usually this step will not be needed.
-
-6.  Run `make`.
-
-    * On Mac, set RUBY\_CODESIGN environment variable with a signing identity.
-      It uses the identity to sign `ruby` binary. See also codesign(1).
-
-7.  Optionally, run '`make check`' to check whether the compiled Ruby
-    interpreter works well. If you see the message "`check succeeded`", your
-    Ruby works as it should (hopefully).
-
-8.  Run '`make install`'.
-
-    This command will create the following directories and install files into
-    them.
-
-    *   `${DESTDIR}${prefix}/bin`
-    *   `${DESTDIR}${prefix}/include/ruby-${MAJOR}.${MINOR}.${TEENY}`
-    *   `${DESTDIR}${prefix}/include/ruby-${MAJOR}.${MINOR}.${TEENY}/${PLATFORM}`
-    *   `${DESTDIR}${prefix}/lib`
-    *   `${DESTDIR}${prefix}/lib/ruby`
-    *   `${DESTDIR}${prefix}/lib/ruby/${MAJOR}.${MINOR}.${TEENY}`
-    *   `${DESTDIR}${prefix}/lib/ruby/${MAJOR}.${MINOR}.${TEENY}/${PLATFORM}`
-    *   `${DESTDIR}${prefix}/lib/ruby/site_ruby`
-    *   `${DESTDIR}${prefix}/lib/ruby/site_ruby/${MAJOR}.${MINOR}.${TEENY}`
-    *   `${DESTDIR}${prefix}/lib/ruby/site_ruby/${MAJOR}.${MINOR}.${TEENY}/${PLATFORM}`
-    *   `${DESTDIR}${prefix}/lib/ruby/vendor_ruby`
-    *   `${DESTDIR}${prefix}/lib/ruby/vendor_ruby/${MAJOR}.${MINOR}.${TEENY}`
-    *   `${DESTDIR}${prefix}/lib/ruby/vendor_ruby/${MAJOR}.${MINOR}.${TEENY}/${PLATFORM}`
-    *   `${DESTDIR}${prefix}/lib/ruby/gems/${MAJOR}.${MINOR}.${TEENY}`
-    *   `${DESTDIR}${prefix}/share/man/man1`
-    *   `${DESTDIR}${prefix}/share/ri/${MAJOR}.${MINOR}.${TEENY}/system`
-
-
-    If Ruby's API version is '*x.y.z*', the `${MAJOR}` is '*x*', the
-    `${MINOR}` is '*y*', and the `${TEENY}` is '*z*'.
-
-    **NOTE**: teeny of the API version may be different from one of Ruby's
-    program version
-
-    You may have to be a super user to install Ruby.
-
-If you fail to compile Ruby, please send the detailed error report with the
-error log and machine/OS type, to help others.
-
-Some extension libraries may not get compiled because of lack of necessary
-external libraries and/or headers, then you will need to run '`make distclean-ext`'
-to remove old configuration after installing them in such case.
+[ruby-talk-request@ruby-lang.org]: mailto:ruby-talk-request@ruby-lang.org?subject=Join%20Ruby%20Mailing%20List&body=subscribe
 
 ## Copying
 
-See the file [COPYING](COPYING).
+See the file [COPYING](rdoc-ref:COPYING).
 
 ## Feedback
 
-Questions about the Ruby language can be asked on the Ruby-Talk mailing list
-(https://www.ruby-lang.org/en/community/mailing-lists) or on websites like
-(https://stackoverflow.com).
-
-Bugs should be reported at https://bugs.ruby-lang.org. Read [HowToReport] for more information.
+Questions about the Ruby language can be asked on the [Ruby-Talk](https://www.ruby-lang.org/en/community/mailing-lists) mailing list
+or on websites like https://stackoverflow.com.
 
-[HowToReport]: https://bugs.ruby-lang.org/projects/ruby/wiki/HowToReport
+Bugs should be reported at https://bugs.ruby-lang.org. Read ["Reporting Issues"](https://docs.ruby-lang.org/en/master/contributing/reporting_issues_md.html) for more information.
 
 ## Contributing
 
-See the file [CONTRIBUTING.md](CONTRIBUTING.md)
+See ["Contributing to Ruby"](https://docs.ruby-lang.org/en/master/contributing_md.html), which includes setup and build instructions.
 
 ## The Author
 
diff --git a/aclocal.m4 b/aclocal.m4
index 940d91e83f..e69de29bb2 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -1,48 +0,0 @@
-# generated automatically by aclocal 1.16.2 -*- Autoconf -*-
-
-# Copyright (C) 1996-2020 Free Software Foundation, Inc.
-
-# This file is free software; the Free Software Foundation
-# gives unlimited permission to copy and/or distribute it,
-# with or without modifications, as long as this notice is preserved.
-
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY, to the extent permitted by law; without
-# even the implied warranty of MERCHANTABILITY or FITNESS FOR A
-# PARTICULAR PURPOSE.
-
-m4_ifndef([AC_CONFIG_MACRO_DIRS], [m4_defun([_AM_CONFIG_MACRO_DIRS], [])m4_defun([AC_CONFIG_MACRO_DIRS], [_AM_CONFIG_MACRO_DIRS($@)])])
-m4_include([tool/m4/_colorize_result_prepare.m4])
-m4_include([tool/m4/ac_msg_result.m4])
-m4_include([tool/m4/colorize_result.m4])
-m4_include([tool/m4/ruby_append_option.m4])
-m4_include([tool/m4/ruby_append_options.m4])
-m4_include([tool/m4/ruby_check_builtin_func.m4])
-m4_include([tool/m4/ruby_check_builtin_setjmp.m4])
-m4_include([tool/m4/ruby_check_printf_prefix.m4])
-m4_include([tool/m4/ruby_check_setjmp.m4])
-m4_include([tool/m4/ruby_check_signedness.m4])
-m4_include([tool/m4/ruby_check_sizeof.m4])
-m4_include([tool/m4/ruby_check_sysconf.m4])
-m4_include([tool/m4/ruby_cppoutfile.m4])
-m4_include([tool/m4/ruby_decl_attribute.m4])
-m4_include([tool/m4/ruby_default_arch.m4])
-m4_include([tool/m4/ruby_define_if.m4])
-m4_include([tool/m4/ruby_defint.m4])
-m4_include([tool/m4/ruby_dtrace_available.m4])
-m4_include([tool/m4/ruby_dtrace_postprocess.m4])
-m4_include([tool/m4/ruby_func_attribute.m4])
-m4_include([tool/m4/ruby_mingw32.m4])
-m4_include([tool/m4/ruby_prepend_option.m4])
-m4_include([tool/m4/ruby_prog_gnu_ld.m4])
-m4_include([tool/m4/ruby_replace_funcs.m4])
-m4_include([tool/m4/ruby_replace_type.m4])
-m4_include([tool/m4/ruby_rm_recursive.m4])
-m4_include([tool/m4/ruby_setjmp_type.m4])
-m4_include([tool/m4/ruby_stack_grow_direction.m4])
-m4_include([tool/m4/ruby_try_cflags.m4])
-m4_include([tool/m4/ruby_try_cxxflags.m4])
-m4_include([tool/m4/ruby_try_ldflags.m4])
-m4_include([tool/m4/ruby_type_attribute.m4])
-m4_include([tool/m4/ruby_universal_arch.m4])
-m4_include([tool/m4/ruby_werror_flag.m4])
diff --git a/addr2line.c b/addr2line.c
index bf6bc6dc24..e5f25293e2 100644
--- a/addr2line.c
+++ b/addr2line.c
@@ -159,11 +159,15 @@ 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 5
+#define DWARF_SECTION_COUNT 9
 
 static struct dwarf_section *
 obj_dwarf_section_at(obj_info_t *obj, int n)
@@ -173,7 +177,11 @@ obj_dwarf_section_at(obj_info_t *obj, int n)
         &obj->debug_info,
         &obj->debug_line,
         &obj->debug_ranges,
-        &obj->debug_str
+        &obj->debug_str_offsets,
+        &obj->debug_addr,
+        &obj->debug_rnglists,
+        &obj->debug_str,
+        &obj->debug_line_str
     };
     if (n < 0 || DWARF_SECTION_COUNT <= n) {
         abort();
@@ -190,12 +198,12 @@ struct debug_section_definition {
 static char binary_filename[PATH_MAX + 1];
 
 static unsigned long
-uleb128(char **p)
+uleb128(const char **p)
 {
     unsigned long r = 0;
     int s = 0;
     for (;;) {
-	unsigned char b = *(unsigned char *)(*p)++;
+	unsigned char b = (unsigned char)*(*p)++;
 	if (b < 0x80) {
 	    r += (unsigned long)b << s;
 	    break;
@@ -207,12 +215,12 @@ uleb128(char **p)
 }
 
 static long
-sleb128(char **p)
+sleb128(const char **p)
 {
     long r = 0;
     int s = 0;
     for (;;) {
-	unsigned char b = *(unsigned char *)(*p)++;
+	unsigned char b = (unsigned char)*(*p)++;
 	if (b < 0x80) {
 	    if (b & 0x40) {
 		r -= (0x80 - b) << s;
@@ -229,7 +237,7 @@ sleb128(char **p)
 }
 
 static const char *
-get_nth_dirname(unsigned long dir, char *p)
+get_nth_dirname(unsigned long dir, const char *p)
 {
     if (!dir--) {
 	return "";
@@ -246,39 +254,51 @@ get_nth_dirname(unsigned long dir, char *p)
     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);
+
 static void
-fill_filename(int file, char *include_directories, 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)
 {
     int i;
-    char *p = filenames;
-    char *filename;
+    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);
+        line->filename = path;
+        parse_ver5_debug_line_header(include_directories, (int)directory_index, format, obj, &path, NULL);
+        line->dirname = path;
+    }
+    else {
+        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);
+            }
+        }
     }
 }
 
 static void
 fill_line(int num_traces, void **traces, uintptr_t addr, int file, int line,
-	  char *include_directories, char *filenames,
+	  uint8_t format, uint16_t version, const char *include_directories, const char *filenames,
 	  obj_info_t *obj, line_info_t *lines, int offset)
 {
     int i;
@@ -288,7 +308,7 @@ fill_line(int num_traces, void **traces, uintptr_t addr, int file, int line,
 	/* 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);
+	    fill_filename(file, format, version, include_directories, filenames, &lines[i], obj);
 	    lines[i].line = line;
 	}
     }
@@ -313,7 +333,7 @@ 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)
 {
     const char *p = *pp;
     header->unit_length = *(uint32_t *)p;
@@ -330,7 +350,13 @@ 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;
@@ -351,20 +377,27 @@ 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);
+        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;
 
@@ -372,7 +405,7 @@ parse_debug_line_header(const char **pp, struct LineNumberProgramHeader *header)
 }
 
 static int
-parse_debug_line_cu(int num_traces, void **traces, char **debug_line,
+parse_debug_line_cu(int num_traces, void **traces, const char **debug_line,
 		obj_info_t *obj, line_info_t *lines, int offset)
 {
     const char *p = (const char *)*debug_line;
@@ -390,15 +423,17 @@ parse_debug_line_cu(int num_traces, void **traces, 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))
         return -1;
     is_stmt = header.default_is_stmt;
 
 #define FILL_LINE()						    \
     do {							    \
 	fill_line(num_traces, traces, addr, file, line,		    \
-                  (char *)header.include_directories,               \
-                  (char *)header.filenames,                         \
+                  header.format,                                    \
+                  header.version,                                   \
+                  header.include_directories,                       \
+                  header.filenames,                                 \
 		  obj, lines, offset);				    \
 	/*basic_block = prologue_end = epilogue_begin = 0;*/	    \
     } while (0)
@@ -411,19 +446,19 @@ parse_debug_line_cu(int num_traces, void **traces, char **debug_line,
 	    FILL_LINE();
 	    break;
 	case DW_LNS_advance_pc:
-	    a = uleb128((char **)&p);
+	    a = uleb128(&p) * header.minimum_instruction_length;
 	    addr += a;
 	    break;
 	case DW_LNS_advance_line: {
-	    long a = sleb128((char **)&p);
+	    long a = sleb128(&p);
 	    line += a;
 	    break;
 	}
 	case DW_LNS_set_file:
-	    file = (unsigned int)uleb128((char **)&p);
+	    file = (unsigned int)uleb128(&p);
 	    break;
 	case DW_LNS_set_column:
-	    /*column = (unsigned int)*/(void)uleb128((char **)&p);
+	    /*column = (unsigned int)*/(void)uleb128(&p);
 	    break;
 	case DW_LNS_negate_stmt:
 	    is_stmt = !is_stmt;
@@ -437,7 +472,8 @@ parse_debug_line_cu(int num_traces, void **traces, char **debug_line,
 	    addr += a;
 	    break;
 	case DW_LNS_fixed_advance_pc:
-	    a = *(unsigned char *)p++;
+	    a = *(uint16_t *)p;
+	    p += sizeof(uint16_t);
 	    addr += a;
 	    break;
 	case DW_LNS_set_prologue_end:
@@ -447,10 +483,10 @@ parse_debug_line_cu(int num_traces, void **traces, char **debug_line,
 	    /* epilogue_begin = 1; */
 	    break;
 	case DW_LNS_set_isa:
-	    /* isa = (unsigned int)*/(void)uleb128((char **)&p);
+	    /* isa = (unsigned int)*/(void)uleb128(&p);
 	    break;
 	case 0:
-	    a = *(unsigned char *)p++;
+	    a = uleb128(&p);
 	    op = *p++;
 	    switch (op) {
 	    case DW_LNE_end_sequence:
@@ -474,7 +510,7 @@ parse_debug_line_cu(int num_traces, void **traces, char **debug_line,
 		break;
 	    case DW_LNE_set_discriminator:
 		/* TODO:currently ignore */
-		uleb128((char **)&p);
+		uleb128(&p);
 		break;
 	    default:
 		kprintf("Unknown extended opcode: %d in %s\n",
@@ -497,10 +533,10 @@ parse_debug_line_cu(int num_traces, void **traces, char **debug_line,
 
 static int
 parse_debug_line(int num_traces, void **traces,
-		 char *debug_line, unsigned long size,
+		 const char *debug_line, unsigned long size,
 		 obj_info_t *obj, line_info_t *lines, int offset)
 {
-    char *debug_line_end = debug_line + size;
+    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;
@@ -526,13 +562,25 @@ append_obj(obj_info_t **objp)
 }
 
 #ifdef USE_ELF
+/* Ideally we should check 4 paths to follow gnu_debuglink:
+ *
+ *   - /usr/lib/debug/.build-id/ab/cdef1234.debug
+ *   - /usr/bin/ruby.debug
+ *   - /usr/bin/.debug/ruby.debug
+ *   - /usr/lib/debug/usr/bin/ruby.debug.
+ *
+ * but we handle only two cases for now as the two formats are
+ * used by some linux distributions.
+ *
+ * See GDB's info for detail.
+ * https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
+ */
+
+// 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)
 {
-    /* Ideally we should check 4 paths to follow gnu_debuglink,
-       but we handle only one case for now as this format is used
-       by some linux distributions. See GDB's info for detail. */
     static const char global_debug_dir[] = "/usr/lib/debug";
     const size_t global_debug_dir_len = sizeof(global_debug_dir) - 1;
     char *p;
@@ -559,6 +607,37 @@ follow_debuglink(const char *debuglink, int num_traces, void **traces,
     o2->path = o1->path;
     fill_lines(num_traces, traces, 0, objp, lines, offset);
 }
+
+// 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)
+{
+    static const char global_debug_dir[] = "/usr/lib/debug/.build-id/";
+    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;
+
+    memcpy(binary_filename, global_debug_dir, global_debug_dir_len);
+    p = binary_filename + global_debug_dir_len;
+    for (i = 0; i < build_id_size; i++) {
+        static const char tbl[] = "0123456789abcdef";
+        unsigned char n = build_id[i];
+        *p++ = tbl[n / 16];
+        *p++ = tbl[n % 16];
+        if (i == 0) *p++ = '/';
+    }
+    strcpy(p, ".debug");
+
+    append_obj(objp);
+    o2 = *objp;
+    o2->base_addr = o1->base_addr;
+    o2->path = o1->path;
+    fill_lines(num_traces, traces, 0, objp, lines, offset);
+}
 #endif
 
 enum
@@ -764,32 +843,51 @@ enum
     DW_FORM_addrx4 = 0x2c
 };
 
+/* Range list entry encodings */
+enum {
+    DW_RLE_end_of_list = 0x00,
+    DW_RLE_base_addressx = 0x01,
+    DW_RLE_startx_endx = 0x02,
+    DW_RLE_startx_length = 0x03,
+    DW_RLE_offset_pair = 0x04,
+    DW_RLE_base_address = 0x05,
+    DW_RLE_start_end = 0x06,
+    DW_RLE_start_length = 0x07
+};
+
 enum {
     VAL_none = 0,
     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;
-    char *file;
-    char *current_cu;
+    const char *file;
+    uint8_t current_version;
+    const char *current_cu;
     uint64_t current_low_pc;
-    char *debug_line_cu_end;
-    char *debug_line_files;
-    char *debug_line_directories;
-    char *p;
-    char *cu_end;
-    char *pend;
-    char *q0;
-    char *q;
+    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;
+    const char *cu_end;
+    const char *pend;
+    const char *q0;
+    const char *q;
     int format; // 4 or 8
     uint8_t address_size;
     int level;
-    char *abbrev_table[ABBREV_TABLE_SIZE];
+    const char *abbrev_table[ABBREV_TABLE_SIZE];
 } DebugInfoReader;
 
 typedef struct {
@@ -800,9 +898,10 @@ typedef struct {
 
 typedef struct {
     union {
-        char *ptr;
+        const char *ptr;
         uint64_t uint64;
         int64_t int64;
+        uint64_t addr_idx;
     } as;
     uint64_t off;
     uint64_t at;
@@ -811,8 +910,11 @@ 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)
@@ -833,39 +935,39 @@ get_uint64(const uint8_t *p)
 }
 
 static uint8_t
-read_uint8(char **ptr)
+read_uint8(const char **ptr)
 {
-    const unsigned char *p = (const unsigned char *)*ptr;
-    *ptr = (char *)(p + 1);
-    return *p;
+    const char *p = *ptr;
+    *ptr = (p + 1);
+    return (uint8_t)*p;
 }
 
 static uint16_t
-read_uint16(char **ptr)
+read_uint16(const char **ptr)
 {
-    const unsigned char *p = (const unsigned char *)*ptr;
-    *ptr = (char *)(p + 2);
-    return get_uint16(p);
+    const char *p = *ptr;
+    *ptr = (p + 2);
+    return get_uint16((const uint8_t *)p);
 }
 
 static uint32_t
-read_uint24(char **ptr)
+read_uint24(const char **ptr)
 {
-    const unsigned char *p = (const unsigned char *)*ptr;
-    *ptr = (char *)(p + 3);
-    return (*p << 16) | get_uint16(p+1);
+    const char *p = *ptr;
+    *ptr = (p + 3);
+    return ((uint8_t)*p << 16) | get_uint16((const uint8_t *)p+1);
 }
 
 static uint32_t
-read_uint32(char **ptr)
+read_uint32(const char **ptr)
 {
-    const unsigned char *p = (const unsigned char *)*ptr;
-    *ptr = (char *)(p + 4);
-    return get_uint32(p);
+    const char *p = *ptr;
+    *ptr = (p + 4);
+    return get_uint32((const uint8_t *)p);
 }
 
 static uint64_t
-read_uint64(char **ptr)
+read_uint64(const char **ptr)
 {
     const unsigned char *p = (const unsigned char *)*ptr;
     *ptr = (char *)(p + 8);
@@ -873,7 +975,7 @@ read_uint64(char **ptr)
 }
 
 static uintptr_t
-read_uintptr(char **ptr)
+read_uintptr(const char **ptr)
 {
     const unsigned char *p = (const unsigned char *)*ptr;
     *ptr = (char *)(p + SIZEOF_VOIDP);
@@ -914,13 +1016,34 @@ debug_info_reader_init(DebugInfoReader *reader, obj_info_t *obj)
     reader->p = obj->debug_info.ptr;
     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
+di_skip_die_attributes(const char **p)
+{
+    for (;;) {
+        uint64_t at = uleb128(p);
+        uint64_t form = uleb128(p);
+        if (!at && !form) break;
+        switch (form) {
+          default:
+            break;
+          case DW_FORM_implicit_const:
+            sleb128(p);
+            break;
+        }
+    }
 }
 
 static void
 di_read_debug_abbrev_cu(DebugInfoReader *reader)
 {
     uint64_t prev = 0;
-    char *p = reader->q0;
+    const char *p = reader->q0;
     for (;;) {
         uint64_t abbrev_number = uleb128(&p);
         if (abbrev_number <= prev) break;
@@ -930,12 +1053,7 @@ di_read_debug_abbrev_cu(DebugInfoReader *reader)
         prev = abbrev_number;
         uleb128(&p); /* tag */
         p++; /* has_children */
-        /* skip content */
-        for (;;) {
-            uint64_t at = uleb128(&p);
-            uint64_t form = uleb128(&p);
-            if (!at && !form) break;
-        }
+        di_skip_die_attributes(&p);
     }
 }
 
@@ -946,10 +1064,12 @@ di_read_debug_line_cu(DebugInfoReader *reader)
     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))
         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;
 
@@ -957,6 +1077,13 @@ 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;
@@ -971,7 +1098,7 @@ set_int_value(DebugInfoValue *v, int64_t n)
 }
 
 static void
-set_cstr_value(DebugInfoValue *v, char *s)
+set_cstr_value(DebugInfoValue *v, const char *s)
 {
     v->as.ptr = s;
     v->off = 0;
@@ -979,7 +1106,7 @@ set_cstr_value(DebugInfoValue *v, char *s)
 }
 
 static void
-set_cstrp_value(DebugInfoValue *v, char *s, uint64_t off)
+set_cstrp_value(DebugInfoValue *v, const char *s, uint64_t off)
 {
     v->as.ptr = s;
     v->off = off;
@@ -987,7 +1114,7 @@ set_cstrp_value(DebugInfoValue *v, char *s, uint64_t off)
 }
 
 static void
-set_data_value(DebugInfoValue *v, char *s)
+set_data_value(DebugInfoValue *v, const char *s)
 {
     v->as.ptr = s;
     v->type = VAL_data;
@@ -1003,19 +1130,39 @@ get_cstr_value(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 void
+debug_info_reader_read_addr_value(DebugInfoReader *reader, DebugInfoValue *v)
+{
+    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();
+    }
+}
+
 static void
 debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoValue *v)
 {
     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);
         break;
       case DW_FORM_block2:
         v->size = read_uint16(&reader->p);
@@ -1067,13 +1214,19 @@ 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->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));
+        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);
         } else {
-            fprintf(stderr,"unknown address_size:%d", reader->address_size);
-            abort();
+            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));
+            } else {
+                fprintf(stderr,"unknown format:%d", reader->format);
+                abort();
+            }
         }
         break;
       case DW_FORM_ref1:
@@ -1115,11 +1268,10 @@ 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));
@@ -1134,8 +1286,7 @@ 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));
@@ -1153,28 +1304,28 @@ 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;
       case 0:
         goto fail;
@@ -1188,10 +1339,10 @@ debug_info_reader_read_value(DebugInfoReader *reader, uint64_t form, DebugInfoVa
 }
 
 /* find abbrev in current compilation unit */
-static char *
+static const char *
 di_find_abbrev(DebugInfoReader *reader, uint64_t abbrev_number)
 {
-    char *p;
+    const char *p;
     if (abbrev_number < ABBREV_TABLE_SIZE) {
         return reader->abbrev_table[abbrev_number];
     }
@@ -1199,12 +1350,7 @@ di_find_abbrev(DebugInfoReader *reader, uint64_t abbrev_number)
     /* skip 255th record */
     uleb128(&p); /* tag */
     p++; /* has_children */
-    /* skip content */
-    for (;;) {
-        uint64_t at = uleb128(&p);
-        uint64_t form = uleb128(&p);
-        if (!at && !form) break;
-    }
+    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);
@@ -1212,12 +1358,7 @@ di_find_abbrev(DebugInfoReader *reader, uint64_t abbrev_number)
         }
         uleb128(&p); /* tag */
         p++; /* has_children */
-        /* skip content */
-        for (;;) {
-            uint64_t at = uleb128(&p);
-            uint64_t form = uleb128(&p);
-            if (!at && !form) break;
-        }
+        di_skip_die_attributes(&p);
     }
     return p;
 }
@@ -1231,7 +1372,7 @@ hexdump0(const unsigned char *p, size_t n)
     for (i=0; i < n; i++){
         switch (i & 15) {
           case 0:
-            fprintf(stderr, "%02zd: %02X ", i/16, p[i]);
+            fprintf(stderr, "%02" PRIdSIZE ": %02X ", i/16, p[i]);
             break;
           case 15:
             fprintf(stderr, "%02X\n", p[i]);
@@ -1252,16 +1393,16 @@ div_inspect(DebugInfoValue *v)
 {
     switch (v->type) {
       case VAL_uint:
-        fprintf(stderr,"%d: type:%d size:%zx v:%lx\n",__LINE__,v->type,v->size,v->as.uint64);
+        fprintf(stderr,"%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:%zx v:%ld\n",__LINE__,v->type,v->size,(int64_t)v->as.uint64);
+        fprintf(stderr,"%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:%zx v:'%s'\n",__LINE__,v->type,v->size,v->as.ptr);
+        fprintf(stderr,"%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:%zx v:\n",__LINE__,v->type,v->size);
+        fprintf(stderr,"%d: type:%d size:%" PRIxSIZE " v:\n",__LINE__,v->type,v->size);
         hexdump(v->as.ptr, 16);
         break;
     }
@@ -1312,6 +1453,76 @@ di_skip_records(DebugInfoReader *reader)
     }
 }
 
+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 void
+addr_header_init(obj_info_t *obj, addr_header_t *header) {
+    const char *p = obj->debug_addr.ptr;
+
+    header->ptr = p;
+
+    if (!p) return;
+
+    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++;
+    p++; /* segment_selector_size */
+}
+
+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 void
+rnglists_header_init(obj_info_t *obj, rnglists_header_t *header) {
+    const char *p = obj->debug_rnglists.ptr;
+
+    if (!p) return;
+
+    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++;
+    p++; /* segment_selector_size */
+    header->offset_entry_count = *(uint32_t *)p;
+}
+
 typedef struct {
     uint64_t low_pc;
     uint64_t high_pc;
@@ -1322,31 +1533,53 @@ 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)
+{
+    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();
+    }
+}
+
 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)
 {
     if (ptr->high_pc_set) {
         if (ptr->ranges_set || !ptr->low_pc_set) {
@@ -1358,8 +1591,66 @@ ranges_include(DebugInfoReader *reader, ranges_t *ptr, uint64_t addr)
     }
     else if (ptr->ranges_set) {
         /* TODO: support base address selection entry */
-        char *p = reader->obj->debug_ranges.ptr + ptr->ranges;
+        const char *p;
         uint64_t base = ptr->low_pc_set ? ptr->low_pc : reader->current_low_pc;
+        bool base_valid = true;
+        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;
+                if (rle == DW_RLE_end_of_list) break;
+                switch (rle) {
+                  case DW_RLE_base_addressx:
+                    uleb128(&p);
+                    base_valid = false; /* not supported yet */
+                    break;
+                  case DW_RLE_startx_endx:
+                    uleb128(&p);
+                    uleb128(&p);
+                    break;
+                  case DW_RLE_startx_length:
+                    uleb128(&p);
+                    uleb128(&p);
+                    break;
+                  case DW_RLE_offset_pair:
+                    if (!base_valid) break;
+                    from = (uintptr_t)base + uleb128(&p);
+                    to = (uintptr_t)base + uleb128(&p);
+                    break;
+                  case DW_RLE_base_address:
+                    base = read_dw_form_addr(reader, &p);
+                    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);
+                    break;
+                  case DW_RLE_start_length:
+                    from = (uintptr_t)read_dw_form_addr(reader, &p);
+                    to = from + uleb128(&p);
+                    break;
+                }
+                if (from <= addr && addr < to) {
+                    return from;
+                }
+            }
+            return false;
+        }
+        p = reader->obj->debug_ranges.ptr + ptr->ranges;
         for (;;) {
             uintptr_t from = read_uintptr(&p);
             uintptr_t to = read_uintptr(&p);
@@ -1369,7 +1660,7 @@ ranges_include(DebugInfoReader *reader, ranges_t *ptr, uint64_t addr)
                 base = to;
             }
             else if (base + from <= addr && addr < base + to) {
-                return from;
+                return (uintptr_t)base + from;
             }
         }
     }
@@ -1427,6 +1718,7 @@ 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;
     }
@@ -1459,30 +1751,76 @@ di_read_cu(DebugInfoReader *reader)
             break;
         }
 
+        reader->current_str_offsets_base = 0;
+        reader->current_addr_base = 0;
+        reader->current_rnglists_base = 0;
+
+        DebugInfoValue low_pc = {{}};
         /* enumerate abbrev */
         for (;;) {
             DebugInfoValue v = {{}};
             if (!di_read_record(reader, &v)) 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;
+                    addr_header_init(reader->obj, &header);
+                    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 abstract_origin, line_info_t *line)
+read_abstract_origin(DebugInfoReader *reader, uint64_t form, uint64_t abstract_origin, line_info_t *line)
 {
-    char *p = reader->p;
-    char *q = reader->q;
+    const char *p = reader->p;
+    const char *q = reader->q;
     int level = reader->level;
     DIE die;
 
-    reader->p = reader->current_cu + abstract_origin;
+    switch (form) {
+      case DW_FORM_ref1:
+      case DW_FORM_ref2:
+      case DW_FORM_ref4:
+      case DW_FORM_ref8:
+      case DW_FORM_ref_udata:
+        reader->p = reader->current_cu + abstract_origin;
+        break;
+      case DW_FORM_ref_addr:
+        goto finish; /* not supported yet */
+      case DW_FORM_ref_sig8:
+        goto finish; /* not supported yet */
+      case DW_FORM_ref_sup4:
+      case DW_FORM_ref_sup8:
+        goto finish; /* not supported yet */
+      default:
+        goto finish;
+    }
     if (!di_read_die(reader, &die)) goto finish;
 
     /* enumerate abbrev */
@@ -1505,6 +1843,13 @@ read_abstract_origin(DebugInfoReader *reader, uint64_t abstract_origin, line_inf
 static void
 debug_info_read(DebugInfoReader *reader, int num_traces, void **traces,
          line_info_t *lines, int offset) {
+
+    addr_header_t addr_header = {};
+    addr_header_init(reader->obj, &addr_header);
+
+    rnglists_header_t rnglists_header = {};
+    rnglists_header_init(reader->obj, &rnglists_header);
+
     while (reader->p < reader->cu_end) {
         DIE die;
         ranges_t ranges = {};
@@ -1531,7 +1876,7 @@ debug_info_read(DebugInfoReader *reader, int num_traces, void **traces,
                 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);
                 break;
               case DW_AT_call_line:
                 line.line = (int)v.as.uint64;
@@ -1539,7 +1884,7 @@ 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;
@@ -1547,7 +1892,7 @@ 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.as.uint64, &line);
+                read_abstract_origin(reader, v.form, v.as.uint64, &line);
                 break; /* goto skip_die; */
             }
         }
@@ -1556,9 +1901,9 @@ debug_info_read(DebugInfoReader *reader, int num_traces, void **traces,
         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);
             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); */
+                /* fprintf(stdout, "%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));
@@ -1577,10 +1922,59 @@ debug_info_read(DebugInfoReader *reader, int num_traces, void **traces,
     }
 }
 
+// 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) {
+    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;
+    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 = {{}};
+            unsigned long dw_lnct = uleb128(&format);
+            unsigned long dw_form = uleb128(&format);
+            debug_info_reader_read_value(&reader, dw_form, &v);
+            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
 static unsigned long
 uncompress_debug_section(ElfW(Shdr) *shdr, char *file, char **ptr)
 {
+    *ptr = NULL;
 #ifdef SUPPORT_COMPRESSED_DEBUG_LINE
     ElfW(Chdr) *chdr = (ElfW(Chdr) *)(file + shdr->sh_offset);
     unsigned long destsize = chdr->ch_size;
@@ -1601,6 +1995,7 @@ uncompress_debug_section(ElfW(Shdr) *shdr, char *file, char **ptr)
 
 fail:
     free(*ptr);
+    *ptr = NULL;
 #endif
     return 0;
 }
@@ -1615,6 +2010,7 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
     ElfW(Ehdr) *ehdr;
     ElfW(Shdr) *shdr, *shstr_shdr;
     ElfW(Shdr) *gnu_debuglink_shdr = NULL;
+    ElfW(Shdr) *note_gnu_build_id = NULL;
     int fd;
     off_t filesize;
     char *file;
@@ -1687,6 +2083,11 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
 	    /* 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;
@@ -1697,7 +2098,11 @@ fill_lines(int num_traces, void **traces, int check_debuglink,
                     ".debug_info",
                     ".debug_line",
                     ".debug_ranges",
-                    ".debug_str"
+                    ".debug_str_offsets",
+                    ".debug_addr",
+                    ".debug_rnglists",
+                    ".debug_str",
+                    ".debug_line_str"
                 };
 
                 for (j=0; j < DWARF_SECTION_COUNT; j++) {
@@ -1802,6 +2207,13 @@ use_symtab:
 			     num_traces, traces,
 			     objp, lines, offset);
 	}
+        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);
+        }
 	goto finish;
     }
 
@@ -1946,7 +2358,11 @@ found_mach_header:
                     "__debug_info",
                     "__debug_line",
                     "__debug_ranges",
-                    "__debug_str"
+                    "__debug_str_offsets",
+                    "__debug_addr",
+                    "__debug_rnglists",
+                    "__debug_str",
+                    "__debug_line_str",
                 };
                 struct LP(segment_command) *scmd = (struct LP(segment_command) *)lcmd;
                 if (strcmp(scmd->segname, "__TEXT") == 0) {
@@ -1983,7 +2399,7 @@ found_mach_header:
                 char *strtab = file + cmd->stroff, *sname = 0;
                 uint32_t j;
                 uintptr_t saddr = 0;
-                /* kprintf("[%2d]: %x/symtab %p\n", i, cmd->cmd, p); */
+                /* kprintf("[%2d]: %x/symtab %p\n", i, cmd->cmd, (void *)p); */
                 for (j = 0; j < cmd->nsyms; j++) {
                     uintptr_t symsize, d;
                     struct LP(nlist) *e = &nl[j];
@@ -2035,7 +2451,7 @@ fail:
 #endif
 
 #define HAVE_MAIN_EXE_PATH
-#if defined(__FreeBSD__)
+#if defined(__FreeBSD__) || defined(__DragonFly__)
 # include <sys/sysctl.h>
 #endif
 /* ssize_t main_exe_path(void)
@@ -2044,17 +2460,21 @@ fail:
  * and returns strlen(binary_filename).
  * it is NUL terminated.
  */
-#if defined(__linux__)
+#if defined(__linux__) || defined(__NetBSD__)
 static ssize_t
 main_exe_path(void)
 {
-# define PROC_SELF_EXE "/proc/self/exe"
+# if defined(__linux__)
+#  define PROC_SELF_EXE "/proc/self/exe"
+# elif defined(__NetBSD__)
+#  define PROC_SELF_EXE "/proc/curproc/exe"
+# endif
     ssize_t len = readlink(PROC_SELF_EXE, binary_filename, PATH_MAX);
     if (len < 0) return 0;
     binary_filename[len] = 0;
     return len;
 }
-#elif defined(__FreeBSD__)
+#elif defined(__FreeBSD__) || defined(__DragonFly__)
 static ssize_t
 main_exe_path(void)
 {
@@ -2098,9 +2518,12 @@ print_line0(line_info_t *line, void *address)
     else if (!line->path) {
         kprintf("[0x%"PRIxPTR"]\n", addr);
     }
-    else if (!line->saddr || !line->sname) {
+    else if (!line->sname) {
         kprintf("%s(0x%"PRIxPTR") [0x%"PRIxPTR"]\n", line->path, addr-line->base_addr, addr);
     }
+    else if (!line->saddr) {
+        kprintf("%s(%s) [0x%"PRIxPTR"]\n", line->path, line->sname, addr);
+    }
     else if (line->line <= 0) {
         kprintf("%s(%s+0x%"PRIxPTR") [0x%"PRIxPTR"]\n", line->path, line->sname,
                 d, addr);
@@ -2137,6 +2560,7 @@ 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;
@@ -2167,8 +2591,8 @@ rb_dump_backtrace_with_lines(int num_traces, void **traces)
 	    /* if the binary is strip-ed, this may effect */
 	    for (p=dladdr_fbases; *p; p++) {
 		if (*p == info.dli_fbase) {
-		    lines[i].path = info.dli_fname;
-		    lines[i].sname = info.dli_sname;
+		    if (info.dli_fname) lines[i].path = info.dli_fname;
+		    if (info.dli_sname) lines[i].sname = info.dli_sname;
 		    goto next_line;
 		}
 	    }
@@ -2178,9 +2602,11 @@ rb_dump_backtrace_with_lines(int num_traces, void **traces)
 	    obj->base_addr = (uintptr_t)info.dli_fbase;
 	    path = info.dli_fname;
 	    obj->path = path;
-	    lines[i].path = path;
-            lines[i].sname = info.dli_sname;
-            lines[i].saddr = (uintptr_t)info.dli_saddr;
+	    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;
diff --git a/appveyor.yml b/appveyor.yml
deleted file mode 100644
index 75452e29ea..0000000000
--- a/appveyor.yml
+++ /dev/null
@@ -1,95 +0,0 @@
----
-version: '{build}'
-init:
-  - git config --global user.name git
-  - git config --global user.email svn-admin@ruby-lang.org
-clone_depth: 10
-platform:
-  - x64
-environment:
-  ruby_version: "24-%Platform%"
-  zlib_version: "1.2.11"
-  matrix:
-    - build: vs
-      vs: 120
-      ssl: OpenSSL
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2013
-      GEMS_FOR_TEST: ""
-    - build: vs
-      vs: 140
-      ssl: OpenSSL-v111
-      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      GEMS_FOR_TEST: ""
-  RELINE_TEST_ENCODING: "Windows-31J"
-  UPDATE_UNICODE: "UNICODE_FILES=. UNICODE_PROPERTY_FILES=. UNICODE_AUXILIARY_FILES=. UNICODE_EMOJI_FILES=."
-for:
--
-  matrix:
-    only:
-      - build: vs
-  install:
-    - ver
-    - chcp
-    - SET BITS=%Platform:x86=32%
-    - SET BITS=%BITS:x=%
-    - SET OPENSSL_DIR=C:\%ssl%-Win%BITS%
-    - 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% touch-unicode-files
-    - nmake %mflags% %UPDATE_UNICODE% incs
-    - nmake %mflags% extract-extlibs
-    - del Makefile
-    - mkdir \usr\local\bin
-    - mkdir \usr\local\include
-    - mkdir \usr\local\lib
-    - curl -fsSL -o zlib%zlib_version:.=%.zip --retry 10 https://zlib.net/zlib%zlib_version:.=%.zip
-    - 7z x -o%APPVEYOR_BUILD_FOLDER%\ext\zlib zlib%zlib_version:.=%.zip
-    - for %%I in (%OPENSSL_DIR%\*.dll) do mklink /h \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 --without-ext=+,dbm,gdbm,readline --with-opt-dir=/usr/local --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 readline --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" test-all 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"
-    - 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/array.c b/array.c
index 1864497e49..b76e9a64a3 100644
--- a/array.c
+++ b/array.c
@@ -39,6 +39,37 @@
 
 VALUE rb_cArray;
 
+/* Flags of RArray
+ *
+ * 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
+ *          by other arrays.
+ *          Note: Frozen arrays may be a shared root without this flag being
+ *                set. Frozen arrays do not have reference counting because
+ *                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.
+ */
+
 /* for OPTIMIZED_CMP: */
 #define id_cmp idCmp
 
@@ -46,28 +77,13 @@ VALUE rb_cArray;
 #define ARY_MAX_SIZE (LONG_MAX / (int)sizeof(VALUE))
 #define SMALL_ARRAY_LEN 16
 
+RBIMPL_ATTR_MAYBE_UNUSED()
 static int
 should_be_T_ARRAY(VALUE ary)
 {
     return RB_TYPE_P(ary, T_ARRAY);
 }
 
-static int
-should_not_be_shared_and_embedded(VALUE ary)
-{
-    return !FL_TEST((ary), ELTS_SHARED) || !FL_TEST((ary), RARRAY_EMBED_FLAG);
-}
-
-#define ARY_SHARED_P(ary) \
-  (assert(should_be_T_ARRAY((VALUE)(ary))), \
-   assert(should_not_be_shared_and_embedded((VALUE)ary)), \
-   FL_TEST_RAW((ary),ELTS_SHARED)!=0)
-
-#define ARY_EMBED_P(ary) \
-  (assert(should_be_T_ARRAY((VALUE)(ary))), \
-   assert(should_not_be_shared_and_embedded((VALUE)ary)), \
-   FL_TEST_RAW((ary), RARRAY_EMBED_FLAG) != 0)
-
 #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)), \
@@ -77,11 +93,11 @@ should_not_be_shared_and_embedded(VALUE ary)
 #define ARY_EMBED_LEN(a) \
     (assert(ARY_EMBED_P(a)), \
      (long)((RBASIC(a)->flags >> RARRAY_EMBED_LEN_SHIFT) & \
-	 (RARRAY_EMBED_LEN_MASK >> 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_OWNS_HEAP_P(a) (assert(should_be_T_ARRAY((VALUE)(a))), \
-                            !FL_TEST_RAW((a), ELTS_SHARED|RARRAY_EMBED_FLAG))
+                            !FL_TEST_RAW((a), RARRAY_SHARED_FLAG|RARRAY_EMBED_FLAG))
 
 #define FL_SET_EMBED(a) do { \
     assert(!ARY_SHARED_P(a)); \
@@ -93,9 +109,9 @@ should_not_be_shared_and_embedded(VALUE ary)
 #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)); \
-    FL_SET((ary), ELTS_SHARED); \
+    FL_SET((ary), RARRAY_SHARED_FLAG); \
 } while (0)
-#define FL_UNSET_SHARED(ary) FL_UNSET((ary), ELTS_SHARED)
+#define FL_UNSET_SHARED(ary) FL_UNSET((ary), RARRAY_SHARED_FLAG)
 
 #define ARY_SET_PTR(ary, p) do { \
     assert(!ARY_EMBED_P(ary)); \
@@ -105,7 +121,6 @@ should_not_be_shared_and_embedded(VALUE ary)
 #define ARY_SET_EMBED_LEN(ary, n) do { \
     long tmp_n = (n); \
     assert(ARY_EMBED_P(ary)); \
-    assert(!OBJ_FROZEN(ary)); \
     RBASIC(ary)->flags &= ~RARRAY_EMBED_LEN_MASK; \
     RBASIC(ary)->flags |= (tmp_n) << RARRAY_EMBED_LEN_SHIFT; \
 } while (0)
@@ -137,7 +152,7 @@ should_not_be_shared_and_embedded(VALUE ary)
     } \
 } while (0)
 
-#define ARY_CAPA(ary) (ARY_EMBED_P(ary) ? RARRAY_EMBED_LEN_MAX : \
+#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(ary, n) do { \
     assert(!ARY_EMBED_P(ary)); \
@@ -146,26 +161,25 @@ should_not_be_shared_and_embedded(VALUE ary)
     RARRAY(ary)->as.heap.aux.capa = (n); \
 } while (0)
 
-#define ARY_SHARED_ROOT(ary) (assert(ARY_SHARED_P(ary)), RARRAY(ary)->as.heap.aux.shared_root)
 #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(ARY_SHARED_ROOT_P(_value_)); \
+    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_); \
 } while (0)
-#define RARRAY_SHARED_ROOT_FLAG FL_USER5
-#define ARY_SHARED_ROOT_P(ary) (assert(should_be_T_ARRAY((VALUE)(ary))), \
-                                FL_TEST_RAW((ary), RARRAY_SHARED_ROOT_FLAG))
-#define ARY_SHARED_ROOT_REFCNT(ary) \
-    (assert(ARY_SHARED_ROOT_P(ary)), RARRAY(ary)->as.heap.aux.capa)
-#define ARY_SHARED_ROOT_OCCUPIED(ary) (ARY_SHARED_ROOT_REFCNT(ary) == 1)
+
+#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); \
     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)); \
     FL_SET((ary), RARRAY_SHARED_ROOT_FLAG); \
@@ -181,6 +195,65 @@ ARY_SET(VALUE a, long i, VALUE v)
 }
 #undef RARRAY_ASET
 
+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);
+    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);
+}
+
+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)
+{
+    /* 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
+rb_ary_size_as_embedded(VALUE ary)
+{
+    size_t real_size;
+
+    if (ARY_EMBED_P(ary)) {
+        real_size = ary_embed_size(ARY_EMBED_LEN(ary));
+    }
+    else if (rb_ary_embeddable_p(ary)) {
+        real_size = ary_embed_size(ARY_HEAP_CAPA(ary));
+    }
+    else {
+        real_size = sizeof(struct RArray);
+    }
+    return real_size;
+}
+
 
 #if ARRAY_DEBUG
 #define ary_verify(ary) ary_verify_(ary, __FILE__, __LINE__)
@@ -190,19 +263,19 @@ ary_verify_(VALUE ary, const char *file, int line)
 {
     assert(RB_TYPE_P(ary, T_ARRAY));
 
-    if (FL_TEST(ary, ELTS_SHARED)) {
-        VALUE root = RARRAY(ary)->as.heap.aux.shared_root;
+    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);
         long len = ARY_HEAP_LEN(ary), root_len = RARRAY_LEN(root);
-        assert(FL_TEST(root, RARRAY_SHARED_ROOT_FLAG));
+        assert(ARY_SHARED_ROOT_P(root) || OBJ_FROZEN(root));
         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) <= RARRAY_EMBED_LEN_MAX);
+        assert(RARRAY_LEN(ary) <= ary_embed_capa(ary));
     }
     else {
 #if 1
@@ -258,7 +331,7 @@ void
 rb_mem_clear(VALUE *mem, long size)
 {
     while (size--) {
-	*mem++ = Qnil;
+        *mem++ = Qnil;
     }
 }
 
@@ -266,7 +339,7 @@ static void
 ary_mem_clear(VALUE ary, long beg, long size)
 {
     RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
-	rb_mem_clear(ptr + beg, size);
+        rb_mem_clear(ptr + beg, size);
     });
 }
 
@@ -274,7 +347,7 @@ static inline void
 memfill(register VALUE *mem, register long size, register VALUE val)
 {
     while (size--) {
-	*mem++ = val;
+        *mem++ = val;
     }
 }
 
@@ -282,8 +355,8 @@ static void
 ary_memfill(VALUE ary, long beg, long size, VALUE val)
 {
     RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
-	memfill(ptr + beg, size, val);
-	RB_OBJ_WRITTEN(ary, Qundef, val);
+        memfill(ptr + beg, size, val);
+        RB_OBJ_WRITTEN(ary, Qundef, val);
     });
 }
 
@@ -352,14 +425,16 @@ ary_heap_free(VALUE ary)
     }
 }
 
-static void
+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);
@@ -377,6 +452,8 @@ ary_heap_realloc(VALUE ary, size_t new_capa)
         SIZED_REALLOC_N(RARRAY(ary)->as.heap.ptr, VALUE, new_capa, old_capa);
     }
     ary_verify(ary);
+
+    return alloc_capa;
 }
 
 #if USE_TRANSIENT_HEAP
@@ -384,14 +461,11 @@ 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);
-        long len  = ARY_HEAP_LEN(ary);
-
-        if (ARY_SHARED_ROOT_P(ary)) {
-            capa = len;
-        }
 
         assert(ARY_OWNS_HEAP_P(ary));
         assert(RARRAY_TRANSIENT_P(ary));
@@ -433,6 +507,27 @@ rb_ary_detransient(VALUE ary)
 }
 #endif
 
+void
+rb_ary_make_embedded(VALUE ary)
+{
+    assert(rb_ary_embeddable_p(ary));
+    if (!ARY_EMBED_P(ary)) {
+        const VALUE *buf = ARY_HEAP_PTR(ary);
+        long len = ARY_HEAP_LEN(ary);
+        bool was_transient = RARRAY_TRANSIENT_P(ary);
+
+        // FL_SET_EMBED also unsets the transient flag
+        FL_SET_EMBED(ary);
+        ARY_SET_EMBED_LEN(ary, len);
+
+        MEMCPY((void *)ARY_EMBED_PTR(ary), (void *)buf, VALUE, len);
+
+        if (!was_transient) {
+            ary_heap_free_ptr(ary, buf, len * sizeof(VALUE));
+        }
+    }
+}
+
 static void
 ary_resize_capa(VALUE ary, long capacity)
 {
@@ -440,7 +535,8 @@ ary_resize_capa(VALUE ary, long capacity)
     assert(!OBJ_FROZEN(ary));
     assert(!ARY_SHARED_P(ary));
 
-    if (capacity > RARRAY_EMBED_LEN_MAX) {
+    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);
@@ -451,9 +547,9 @@ ary_resize_capa(VALUE ary, long capacity)
             ARY_SET_HEAP_LEN(ary, len);
         }
         else {
-            ary_heap_realloc(ary, capacity);
+            new_capa = ary_heap_realloc(ary, capacity);
         }
-        ARY_SET_CAPA(ary, capacity);
+        ARY_SET_CAPA(ary, new_capa);
     }
     else {
         if (!ARY_EMBED_P(ary)) {
@@ -491,10 +587,10 @@ ary_double_capa(VALUE ary, long min)
     long new_capa = ARY_CAPA(ary) / 2;
 
     if (new_capa < ARY_DEFAULT_SIZE) {
-	new_capa = ARY_DEFAULT_SIZE;
+        new_capa = ARY_DEFAULT_SIZE;
     }
     if (new_capa >= ARY_MAX_SIZE - min) {
-	new_capa = (ARY_MAX_SIZE - min) / 2;
+        new_capa = (ARY_MAX_SIZE - min) / 2;
     }
     new_capa += min;
     ary_resize_capa(ary, new_capa);
@@ -505,39 +601,40 @@ ary_double_capa(VALUE ary, long min)
 static void
 rb_ary_decrement_share(VALUE shared_root)
 {
-    if (shared_root) {
-        long num = ARY_SHARED_ROOT_REFCNT(shared_root) - 1;
-	if (num == 0) {
-            rb_ary_free(shared_root);
-            rb_gc_force_recycle(shared_root);
-	}
-	else if (num > 0) {
-            ARY_SET_SHARED_ROOT_REFCNT(shared_root, num);
-	}
+    if (!OBJ_FROZEN(shared_root)) {
+        long num = ARY_SHARED_ROOT_REFCNT(shared_root);
+        ARY_SET_SHARED_ROOT_REFCNT(shared_root, num - 1);
     }
 }
 
 static void
 rb_ary_unshare(VALUE ary)
 {
-    VALUE shared_root = RARRAY(ary)->as.heap.aux.shared_root;
+    VALUE shared_root = ARY_SHARED_ROOT(ary);
     rb_ary_decrement_share(shared_root);
     FL_UNSET_SHARED(ary);
 }
 
-static inline void
-rb_ary_unshare_safe(VALUE ary)
+static void
+rb_ary_reset(VALUE ary)
 {
-    if (ARY_SHARED_P(ary) && !ARY_EMBED_P(ary)) {
-	rb_ary_unshare(ary);
+    if (ARY_OWNS_HEAP_P(ary)) {
+        ary_heap_free(ary);
     }
+    else if (ARY_SHARED_P(ary)) {
+        rb_ary_unshare(ary);
+    }
+
+    FL_SET_EMBED(ary);
+    ARY_SET_EMBED_LEN(ary, 0);
 }
 
 static VALUE
 rb_ary_increment_share(VALUE shared_root)
 {
-    long num = ARY_SHARED_ROOT_REFCNT(shared_root);
-    if (num >= 0) {
+    if (!OBJ_FROZEN(shared_root)) {
+        long num = ARY_SHARED_ROOT_REFCNT(shared_root);
+        assert(num >= 0);
         ARY_SET_SHARED_ROOT_REFCNT(shared_root, num + 1);
     }
     return shared_root;
@@ -560,34 +657,33 @@ rb_ary_modify_check(VALUE ary)
 }
 
 void
-rb_ary_modify(VALUE ary)
+rb_ary_cancel_sharing(VALUE ary)
 {
-    rb_ary_modify_check(ary);
     if (ARY_SHARED_P(ary)) {
-	long shared_len, len = RARRAY_LEN(ary);
+        long shared_len, len = RARRAY_LEN(ary);
         VALUE shared_root = ARY_SHARED_ROOT(ary);
 
         ary_verify(shared_root);
 
-        if (len <= RARRAY_EMBED_LEN_MAX) {
-	    const VALUE *ptr = ARY_HEAP_PTR(ary);
+        if (len <= ary_embed_capa(ary)) {
+            const VALUE *ptr = ARY_HEAP_PTR(ary);
             FL_UNSET_SHARED(ary);
             FL_SET_EMBED(ary);
-	    MEMCPY((VALUE *)ARY_EMBED_PTR(ary), ptr, VALUE, len);
+            MEMCPY((VALUE *)ARY_EMBED_PTR(ary), ptr, VALUE, len);
             rb_ary_decrement_share(shared_root);
             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);
-	    FL_UNSET_SHARED(ary);
+            FL_UNSET_SHARED(ary);
             ARY_SET_PTR(ary, RARRAY_CONST_PTR_TRANSIENT(shared_root));
-	    ARY_SET_CAPA(ary, shared_len);
+            ARY_SET_CAPA(ary, shared_len);
             RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
-		MEMMOVE(ptr, ptr+shift, VALUE, len);
-	    });
+                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);
             MEMCPY(ptr, ARY_HEAP_PTR(ary), VALUE, len);
@@ -596,11 +692,18 @@ rb_ary_modify(VALUE ary)
             ARY_SET_PTR(ary, ptr);
         }
 
-	rb_gc_writebarrier_remember(ary);
+        rb_gc_writebarrier_remember(ary);
     }
     ary_verify(ary);
 }
 
+void
+rb_ary_modify(VALUE ary)
+{
+    rb_ary_modify_check(ary);
+    rb_ary_cancel_sharing(ary);
+}
+
 static VALUE
 ary_ensure_room_for_push(VALUE ary, long add_len)
 {
@@ -609,40 +712,40 @@ ary_ensure_room_for_push(VALUE ary, long add_len)
     long capa;
 
     if (old_len > ARY_MAX_SIZE - add_len) {
-	rb_raise(rb_eIndexError, "index %ld too big", new_len);
+        rb_raise(rb_eIndexError, "index %ld too big", new_len);
     }
     if (ARY_SHARED_P(ary)) {
-	if (new_len > RARRAY_EMBED_LEN_MAX) {
+        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)) {
-		    rb_ary_modify_check(ary);
+                    rb_ary_modify_check(ary);
 
                     ary_verify(ary);
                     ary_verify(shared_root);
                     return shared_root;
-		}
-		else {
-		    /* if array is shared, then it is likely it participate in push/shift pattern */
-		    rb_ary_modify(ary);
-		    capa = ARY_CAPA(ary);
-		    if (new_len > capa - (capa >> 6)) {
-			ary_double_capa(ary, new_len);
-		    }
+                }
+                else {
+                    /* if array is shared, then it is likely it participate in push/shift pattern */
+                    rb_ary_modify(ary);
+                    capa = ARY_CAPA(ary);
+                    if (new_len > capa - (capa >> 6)) {
+                        ary_double_capa(ary, new_len);
+                    }
                     ary_verify(ary);
-		    return ary;
-		}
-	    }
-	}
+                    return ary;
+                }
+            }
+        }
         ary_verify(ary);
         rb_ary_modify(ary);
     }
     else {
-	rb_ary_modify_check(ary);
+        rb_ary_modify_check(ary);
     }
     capa = ARY_CAPA(ary);
     if (new_len > capa) {
-	ary_double_capa(ary, new_len);
+        ary_double_capa(ary, new_len);
     }
 
     ary_verify(ary);
@@ -654,15 +757,13 @@ ary_ensure_room_for_push(VALUE ary, long add_len)
  *    array.freeze -> self
  *
  *  Freezes +self+; returns +self+:
+ *
  *    a = []
  *    a.frozen? # => false
- *    a1 = a.freeze # => []
+ *    a.freeze
  *    a.frozen? # => true
- *    a1.equal?(a) # => true # Returned self
  *
- *  An attempt to modify a frozen \Array raises an exception:
- *    # Raises FrozenError (can't modify frozen Array: [:foo, "bar", 2]):
- *    [:foo, 'bar', 2].freeze.push(:foo)
+ *  An attempt to modify a frozen \Array raises FrozenError.
  */
 
 VALUE
@@ -682,18 +783,25 @@ VALUE
 rb_ary_shared_with_p(VALUE ary1, VALUE ary2)
 {
     if (!ARY_EMBED_P(ary1) && ARY_SHARED_P(ary1) &&
-	!ARY_EMBED_P(ary2) && ARY_SHARED_P(ary2) &&
-        RARRAY(ary1)->as.heap.aux.shared_root == RARRAY(ary2)->as.heap.aux.shared_root &&
-	RARRAY(ary1)->as.heap.len == RARRAY(ary2)->as.heap.len) {
-	return Qtrue;
+            !ARY_EMBED_P(ary2) && ARY_SHARED_P(ary2) &&
+            ARY_SHARED_ROOT(ary1) == ARY_SHARED_ROOT(ary2) &&
+            ARY_HEAP_LEN(ary1) == ARY_HEAP_LEN(ary2)) {
+        return Qtrue;
     }
     return Qfalse;
 }
 
 static VALUE
-ary_alloc(VALUE klass)
+ary_alloc_embed(VALUE klass, long capa)
 {
-    NEWOBJ_OF(ary, struct RArray, klass, T_ARRAY | RARRAY_EMBED_FLAG | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0));
+    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,
+                     T_ARRAY | RARRAY_EMBED_FLAG | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0),
+                     size);
     /* Created array is:
      *   FL_SET_EMBED((VALUE)ary);
      *   ARY_SET_EMBED_LEN((VALUE)ary, 0);
@@ -702,10 +810,19 @@ ary_alloc(VALUE klass)
 }
 
 static VALUE
+ary_alloc_heap(VALUE klass)
+{
+    RVARGC_NEWOBJ_OF(ary, struct RArray, klass,
+                     T_ARRAY | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0),
+                     sizeof(struct RArray));
+    return (VALUE)ary;
+}
+
+static VALUE
 empty_ary_alloc(VALUE klass)
 {
     RUBY_DTRACE_CREATE_HOOK(ARRAY, 0);
-    return ary_alloc(klass);
+    return ary_alloc_embed(klass, 0);
 }
 
 static VALUE
@@ -714,20 +831,24 @@ ary_new(VALUE klass, long capa)
     VALUE ary,*ptr;
 
     if (capa < 0) {
-	rb_raise(rb_eArgError, "negative array size (or size too big)");
+        rb_raise(rb_eArgError, "negative array size (or size too big)");
     }
     if (capa > ARY_MAX_SIZE) {
-	rb_raise(rb_eArgError, "array size too big");
+        rb_raise(rb_eArgError, "array size too big");
     }
 
     RUBY_DTRACE_CREATE_HOOK(ARRAY, capa);
 
-    ary = ary_alloc(klass);
-    if (capa > RARRAY_EMBED_LEN_MAX) {
+    if (ary_embeddable_p(capa)) {
+        ary = ary_alloc_embed(klass, capa);
+    }
+    else {
+        ary = ary_alloc_heap(klass);
+        ARY_SET_CAPA(ary, capa);
+        assert(!ARY_EMBED_P(ary));
+
         ptr = ary_heap_alloc(ary, capa);
-        FL_UNSET_EMBED(ary);
         ARY_SET_PTR(ary, ptr);
-        ARY_SET_CAPA(ary, capa);
         ARY_SET_HEAP_LEN(ary, 0);
     }
 
@@ -743,7 +864,7 @@ rb_ary_new_capa(long capa)
 VALUE
 rb_ary_new(void)
 {
-    return rb_ary_new2(RARRAY_EMBED_LEN_MAX);
+    return rb_ary_new_capa(0);
 }
 
 VALUE
@@ -757,7 +878,7 @@ VALUE
 
     va_start(ar, n);
     for (i=0; i<n; i++) {
-	ARY_SET(ary, i, va_arg(ar, VALUE));
+        ARY_SET(ary, i, va_arg(ar, VALUE));
     }
     va_end(ar);
 
@@ -772,8 +893,8 @@ rb_ary_tmp_new_from_values(VALUE klass, long n, const VALUE *elts)
 
     ary = ary_new(klass, n);
     if (n > 0 && elts) {
-	ary_memcpy(ary, 0, n, elts);
-	ARY_SET_LEN(ary, n);
+        ary_memcpy(ary, 0, n, elts);
+        ARY_SET_LEN(ary, n);
     }
 
     return ary;
@@ -785,8 +906,79 @@ rb_ary_new_from_values(long n, const VALUE *elts)
     return rb_ary_tmp_new_from_values(rb_cArray, n, elts);
 }
 
+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);
+    /* Created array is:
+     *   FL_SET_EMBED((VALUE)ary);
+     *   ARY_SET_EMBED_LEN((VALUE)ary, 0);
+     */
+    return (VALUE)ary;
+}
+
+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));
+    return (VALUE)ary;
+}
+
+static VALUE
+ec_ary_new(rb_execution_context_t *ec, VALUE klass, long capa)
+{
+    VALUE ary,*ptr;
+
+    if (capa < 0) {
+        rb_raise(rb_eArgError, "negative array size (or size too big)");
+    }
+    if (capa > ARY_MAX_SIZE) {
+        rb_raise(rb_eArgError, "array size too big");
+    }
+
+    RUBY_DTRACE_CREATE_HOOK(ARRAY, capa);
+
+    if (ary_embeddable_p(capa)) {
+        ary = ec_ary_alloc_embed(ec, klass, capa);
+    }
+    else {
+        ary = ec_ary_alloc_heap(ec, klass);
+        ARY_SET_CAPA(ary, capa);
+        assert(!ARY_EMBED_P(ary));
+
+        ptr = ary_heap_alloc(ary, capa);
+        ARY_SET_PTR(ary, ptr);
+        ARY_SET_HEAP_LEN(ary, 0);
+    }
+
+    return ary;
+}
+
+VALUE
+rb_ec_ary_new_from_values(rb_execution_context_t *ec, long n, const VALUE *elts)
+{
+    VALUE ary;
+
+    ary = ec_ary_new(ec, rb_cArray, n);
+    if (n > 0 && elts) {
+        ary_memcpy(ary, 0, n, elts);
+        ARY_SET_LEN(ary, n);
+    }
+
+    return ary;
+}
+
 VALUE
-rb_ary_tmp_new(long capa)
+rb_ary_hidden_new(long capa)
 {
     VALUE ary = ary_new(0, capa);
     rb_ary_transient_heap_evacuate(ary, TRUE);
@@ -794,12 +986,11 @@ rb_ary_tmp_new(long capa)
 }
 
 VALUE
-rb_ary_tmp_new_fill(long capa)
+rb_ary_hidden_new_fill(long capa)
 {
-    VALUE ary = ary_new(0, capa);
+    VALUE ary = rb_ary_hidden_new(capa);
     ary_memfill(ary, 0, capa, Qnil);
     ARY_SET_LEN(ary, capa);
-    rb_ary_transient_heap_evacuate(ary, TRUE);
     return ary;
 }
 
@@ -837,64 +1028,69 @@ RUBY_FUNC_EXPORTED size_t
 rb_ary_memsize(VALUE ary)
 {
     if (ARY_OWNS_HEAP_P(ary)) {
-	return ARY_CAPA(ary) * sizeof(VALUE);
+        return ARY_CAPA(ary) * sizeof(VALUE);
     }
     else {
-	return 0;
+        return 0;
     }
 }
 
-static inline void
-ary_discard(VALUE ary)
-{
-    rb_ary_free(ary);
-    RBASIC(ary)->flags |= RARRAY_EMBED_FLAG;
-    RBASIC(ary)->flags &= ~(RARRAY_EMBED_LEN_MASK | RARRAY_TRANSIENT_FLAG);
-}
-
 static VALUE
 ary_make_shared(VALUE ary)
 {
-    assert(!ARY_EMBED_P(ary));
+    assert(USE_RVARGC || !ARY_EMBED_P(ary));
     ary_verify(ary);
 
     if (ARY_SHARED_P(ary)) {
         return ARY_SHARED_ROOT(ary);
     }
     else if (ARY_SHARED_ROOT_P(ary)) {
-	return ary;
+        return ary;
     }
     else if (OBJ_FROZEN(ary)) {
-        rb_ary_transient_heap_evacuate(ary, TRUE);
-	ary_shrink_capa(ary);
-	FL_SET_SHARED_ROOT(ary);
-        ARY_SET_SHARED_ROOT_REFCNT(ary, 1);
-	return ary;
+        if (!ARY_EMBED_P(ary)) {
+            rb_ary_transient_heap_evacuate(ary, TRUE);
+            ary_shrink_capa(ary);
+        }
+        return ary;
     }
     else {
-	long capa = ARY_CAPA(ary), len = RARRAY_LEN(ary);
-        const VALUE *ptr;
-	NEWOBJ_OF(shared, struct RArray, 0, T_ARRAY | (RGENGC_WB_PROTECTED_ARRAY ? FL_WB_PROTECTED : 0));
-        VALUE vshared = (VALUE)shared;
-
         rb_ary_transient_heap_evacuate(ary, TRUE);
-        ptr = ARY_HEAP_PTR(ary);
-
-        FL_UNSET_EMBED(vshared);
-        ARY_SET_LEN(vshared, capa);
-        ARY_SET_PTR(vshared, ptr);
-        ary_mem_clear(vshared, len, capa - len);
-        FL_SET_SHARED_ROOT(vshared);
-        ARY_SET_SHARED_ROOT_REFCNT(vshared, 1);
-	FL_SET_SHARED(ary);
+
+        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);
+            ARY_SET_PTR(shared, ptr);
+            ary_memcpy(shared, 0, len, RARRAY_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_LEN(shared, capa);
+        ary_mem_clear(shared, len, capa - len);
+        ARY_SET_SHARED_ROOT_REFCNT(shared, 1);
+        FL_SET_SHARED(ary);
         RB_DEBUG_COUNTER_INC(obj_ary_shared_create);
-        ARY_SET_SHARED(ary, vshared);
-        OBJ_FREEZE(vshared);
+        ARY_SET_SHARED(ary, shared);
 
-        ary_verify(vshared);
+        ary_verify(shared);
         ary_verify(ary);
 
-        return vshared;
+        return shared;
     }
 }
 
@@ -903,8 +1099,10 @@ ary_make_substitution(VALUE ary)
 {
     long len = RARRAY_LEN(ary);
 
-    if (len <= RARRAY_EMBED_LEN_MAX) {
-	VALUE subst = rb_ary_new2(len);
+    if (ary_embeddable_p(len)) {
+        VALUE subst = rb_ary_new_capa(len);
+        assert(ARY_EMBED_P(subst));
+
         ary_memcpy(subst, 0, len, RARRAY_CONST_PTR_TRANSIENT(ary));
         ARY_SET_EMBED_LEN(subst, len);
         return subst;
@@ -939,28 +1137,24 @@ rb_check_to_array(VALUE ary)
     return rb_check_convert_type_with_id(ary, T_ARRAY, "Array", idTo_a);
 }
 
+VALUE
+rb_to_array(VALUE ary)
+{
+    return rb_convert_type_with_id(ary, T_ARRAY, "Array", idTo_a);
+}
+
 /*
  *  call-seq:
- *    Array.try_convert(object) -> new_array or nil
+ *    Array.try_convert(object) -> object, new_array, or nil
  *
- *  Tries to convert +object+ to an \Array.
+ *  If +object+ is an \Array object, returns +object+.
  *
- *  When +object+ is an
- *  {Array-convertible object}[doc/implicit_conversion_rdoc.html#label-Array-Convertible+Objects]
- *  (implements +to_ary+),
- *  returns the \Array object created by converting it:
+ *  Otherwise if +object+ responds to <tt>:to_ary</tt>,
+ *  calls <tt>object.to_ary</tt> and returns the result.
  *
- *    class ToAryReturnsArray < Set
- *      def to_ary
- *        self.to_a
- *      end
- *    end
- *    as = ToAryReturnsArray.new([:foo, :bar, :baz])
- *    Array.try_convert(as) # => [:foo, :bar, :baz]
+ *  Returns +nil+ if +object+ does not respond to <tt>:to_ary</tt>
  *
- *  Returns +nil+ if +object+ is not \Array-convertible:
- *
- *    Array.try_convert(:foo) # => nil
+ *  Raises an exception unless <tt>object.to_ary</tt> returns an \Array object.
  */
 
 static VALUE
@@ -969,6 +1163,30 @@ rb_ary_s_try_convert(VALUE dummy, VALUE ary)
     return rb_check_array_type(ary);
 }
 
+/* :nodoc: */
+static VALUE
+rb_ary_s_new(int argc, VALUE *argv, VALUE klass)
+{
+    VALUE ary;
+
+    if (klass == rb_cArray) {
+        long size = 0;
+        if (argc > 0 && FIXNUM_P(argv[0])) {
+            size = FIX2LONG(argv[0]);
+            if (size < 0) size = 0;
+        }
+
+        ary = ary_new(klass, size);
+
+        rb_obj_call_init_kw(ary, argc, argv, RB_PASS_CALLED_KEYWORDS);
+    }
+    else {
+        ary = rb_class_new_instance_pass_kw(argc, argv, klass);
+    }
+
+    return ary;
+}
+
 /*
  *  call-seq:
  *    Array.new -> new_empty_array
@@ -979,88 +1197,42 @@ rb_ary_s_try_convert(VALUE dummy, VALUE ary)
  *
  *  Returns a new \Array.
  *
- *  Argument +array+, if given, must be an
- *  {Array-convertible object}[doc/implicit_conversion_rdoc.html#label-Array-Convertible+Objects]
- *  (implements +to_ary+).
- *
- *  Argument +size+, if given must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects]
- *  (implements +to_int+).
- *
- *  Argument +default_value+ may be any object.
+ *  With no block and no arguments, returns a new empty \Array object.
  *
- *  ---
- *
- *  With no block and no arguments, returns a new empty \Array object:
- *
- *    a = Array.new
- *    a # => []
- *
- *  With no block and a single argument +array+,
+ *  With no block and a single \Array argument +array+,
  *  returns a new \Array formed from +array+:
  *
  *    a = Array.new([:foo, 'bar', 2])
  *    a.class # => Array
  *    a # => [:foo, "bar", 2]
  *
- *  With no block and a single argument +size+,
+ *  With no block and a single \Integer argument +size+,
  *  returns a new \Array of the given size
  *  whose elements are all +nil+:
  *
- *    a = Array.new(0)
- *    a # => []
  *    a = Array.new(3)
  *    a # => [nil, nil, nil]
  *
- *  With no block and arguments +size+ and  +default_value+,
+ *  With no block and arguments +size+ and +default_value+,
  *  returns an \Array of the given size;
  *  each element is that same +default_value+:
  *
  *    a = Array.new(3, 'x')
  *    a # => ['x', 'x', 'x']
- *    a[1].equal?(a[0]) # => true # Identity check.
- *    a[2].equal?(a[0]) # => true # Identity check.
  *
  *  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 = Array.new(3) { |index| "Element #{index}" }
+ *    a = Array.new(3) {|index| "Element #{index}" }
  *    a # => ["Element 0", "Element 1", "Element 2"]
  *
+ *  Raises ArgumentError if +size+ is negative.
+ *
  *  With a block and no argument,
  *  or a single argument +0+,
- *  ignores the block and returns a new empty \Array:
- *
- *    a = Array.new(0) { |n| raise 'Cannot happen' }
- *    a # => []
- *    a = Array.new { |n| raise 'Cannot happen' }
- *    a # => []
- *
- *  With a block and arguments +size+ and +default_value+,
- *  gives a warning message
- *  ('warning: block supersedes default value argument'),
- *  and assigns elements from the block's return values:
- *
- *    Array.new(4, :default) {} # => [nil, nil, nil, nil]
- *
- *  ---
- *
- *  Raises an exception if +size+ is a negative integer:
- *
- *    # Raises ArgumentError (negative array size):
- *    Array.new(-1)
- *    # Raises ArgumentError (negative array size):
- *    Array.new(-1, :default)
- *    # Raises ArgumentError (negative array size):
- *    Array.new(-1) { |n| }
- *
- *  Raises an exception if the single argument is neither \Array-convertible
- *  nor \Integer-convertible.
- *
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    Array.new(:foo)
+ *  ignores the block and returns a new empty \Array.
  */
 
 static VALUE
@@ -1071,51 +1243,48 @@ rb_ary_initialize(int argc, VALUE *argv, VALUE ary)
 
     rb_ary_modify(ary);
     if (argc == 0) {
-        if (ARY_OWNS_HEAP_P(ary) && ARY_HEAP_PTR(ary) != NULL) {
-            ary_heap_free(ary);
-	}
-        rb_ary_unshare_safe(ary);
-        FL_SET_EMBED(ary);
-	ARY_SET_EMBED_LEN(ary, 0);
-	if (rb_block_given_p()) {
-	    rb_warning("given block not used");
-	}
-	return ary;
+        rb_ary_reset(ary);
+        assert(ARY_EMBED_P(ary));
+        assert(ARY_EMBED_LEN(ary) == 0);
+        if (rb_block_given_p()) {
+            rb_warning("given block not used");
+        }
+        return ary;
     }
     rb_scan_args(argc, argv, "02", &size, &val);
     if (argc == 1 && !FIXNUM_P(size)) {
-	val = rb_check_array_type(size);
-	if (!NIL_P(val)) {
-	    rb_ary_replace(ary, val);
-	    return ary;
-	}
+        val = rb_check_array_type(size);
+        if (!NIL_P(val)) {
+            rb_ary_replace(ary, val);
+            return ary;
+        }
     }
 
     len = NUM2LONG(size);
     /* NUM2LONG() may call size.to_int, ary can be frozen, modified, etc */
     if (len < 0) {
-	rb_raise(rb_eArgError, "negative array size");
+        rb_raise(rb_eArgError, "negative array size");
     }
     if (len > ARY_MAX_SIZE) {
-	rb_raise(rb_eArgError, "array size too big");
+        rb_raise(rb_eArgError, "array size too big");
     }
     /* recheck after argument conversion */
     rb_ary_modify(ary);
     ary_resize_capa(ary, len);
     if (rb_block_given_p()) {
-	long i;
+        long i;
 
-	if (argc == 2) {
-	    rb_warn("block supersedes default value argument");
-	}
-	for (i=0; i<len; i++) {
-	    rb_ary_store(ary, i, rb_yield(LONG2NUM(i)));
-	    ARY_SET_LEN(ary, i + 1);
-	}
+        if (argc == 2) {
+            rb_warn("block supersedes default value argument");
+        }
+        for (i=0; i<len; i++) {
+            rb_ary_store(ary, i, rb_yield(LONG2NUM(i)));
+            ARY_SET_LEN(ary, i + 1);
+        }
     }
     else {
-	ary_memfill(ary, 0, len, val);
-	ARY_SET_LEN(ary, len);
+        ary_memfill(ary, 0, len, val);
+        ARY_SET_LEN(ary, len);
     }
     return ary;
 }
@@ -1146,26 +1315,26 @@ rb_ary_store(VALUE ary, long idx, VALUE val)
     long len = RARRAY_LEN(ary);
 
     if (idx < 0) {
-	idx += len;
-	if (idx < 0) {
-	    rb_raise(rb_eIndexError, "index %ld too small for array; minimum: %ld",
-		     idx - len, -len);
-	}
+        idx += len;
+        if (idx < 0) {
+            rb_raise(rb_eIndexError, "index %ld too small for array; minimum: %ld",
+                     idx - len, -len);
+        }
     }
     else if (idx >= ARY_MAX_SIZE) {
-	rb_raise(rb_eIndexError, "index %ld too big", idx);
+        rb_raise(rb_eIndexError, "index %ld too big", idx);
     }
 
     rb_ary_modify(ary);
     if (idx >= ARY_CAPA(ary)) {
-	ary_double_capa(ary, idx);
+        ary_double_capa(ary, idx);
     }
     if (idx > len) {
-	ary_mem_clear(ary, len, idx - len + 1);
+        ary_mem_clear(ary, len, idx - len + 1);
     }
 
     if (idx >= len) {
-	ARY_SET_LEN(ary, idx + 1);
+        ARY_SET_LEN(ary, idx + 1);
     }
     ARY_SET(ary, idx, val);
 }
@@ -1177,17 +1346,20 @@ ary_make_partial(VALUE ary, VALUE klass, long offset, long len)
     assert(len >= 0);
     assert(offset+len <= RARRAY_LEN(ary));
 
-    if (len <= RARRAY_EMBED_LEN_MAX) {
-        VALUE result = ary_alloc(klass);
+    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);
         ARY_SET_EMBED_LEN(result, len);
         return result;
     }
     else {
-        VALUE shared, result = ary_alloc(klass);
-        FL_UNSET_EMBED(result);
+        VALUE shared = ary_make_shared(ary);
+
+        VALUE result = ary_alloc_heap(klass);
+        assert(!ARY_EMBED_P(result));
 
-        shared = ary_make_shared(ary);
         ARY_SET_PTR(result, RARRAY_CONST_PTR_TRANSIENT(ary));
         ARY_SET_LEN(result, RARRAY_LEN(ary));
         rb_ary_set_shared(result, shared);
@@ -1202,9 +1374,59 @@ ary_make_partial(VALUE ary, VALUE klass, long offset, long len)
 }
 
 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);
+
+    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);
+        RB_OBJ_WRITE(result, ptr, values[offset]);
+        ARY_SET_EMBED_LEN(result, 1);
+        return result;
+    }
+    else if (step < 0 && step < -len) {
+        step = -len;
+    }
+
+    long ustep = (step < 0) ? -step : step;
+    len = roomof(len, ustep);
+
+    long i;
+    long j = offset + ((step > 0) ? 0 : (orig_len - 1));
+
+    VALUE result = ary_new(klass, len);
+    if (ARY_EMBED_P(result)) {
+        VALUE *ptr = (VALUE *)ARY_EMBED_PTR(result);
+        for (i = 0; i < len; ++i) {
+            RB_OBJ_WRITE(result, ptr+i, values[j]);
+            j += step;
+        }
+        ARY_SET_EMBED_LEN(result, len);
+    }
+    else {
+        RARRAY_PTR_USE_TRANSIENT(result, ptr, {
+            for (i = 0; i < len; ++i) {
+                RB_OBJ_WRITE(result, ptr+i, values[j]);
+                j += step;
+            }
+        });
+        ARY_SET_LEN(result, len);
+    }
+
+    return result;
+}
+
+static VALUE
 ary_make_shared_copy(VALUE ary)
 {
-    return ary_make_partial(ary, rb_obj_class(ary), 0, RARRAY_LEN(ary));
+    return ary_make_partial(ary, rb_cArray, 0, RARRAY_LEN(ary));
 }
 
 enum ary_take_pos_flags
@@ -1229,13 +1451,13 @@ ary_take_first_or_last(int argc, const VALUE *argv, VALUE ary, enum ary_take_pos
     n = NUM2LONG(argv[0]);
     len = RARRAY_LEN(ary);
     if (n > len) {
-	n = len;
+        n = len;
     }
     else if (n < 0) {
-	rb_raise(rb_eArgError, "negative array size");
+        rb_raise(rb_eArgError, "negative array size");
     }
     if (last) {
-	offset = len - n;
+        offset = len - n;
     }
     return ary_make_partial(ary, rb_cArray, offset, n);
 }
@@ -1245,16 +1467,16 @@ ary_take_first_or_last(int argc, const VALUE *argv, VALUE ary, enum ary_take_pos
  *    array << object -> self
  *
  *  Appends +object+ to +self+; returns +self+:
+ *
  *    a = [:foo, 'bar', 2]
- *    a1 = a << :baz
- *    a1 # => [:foo, "bar", 2, :baz]
- *    a1.equal?(a) # => true # Returned self
+ *    a << :baz # => [:foo, "bar", 2, :baz]
  *
  *  Appends +object+ as one element, even if it is another \Array:
  *
  *    a = [:foo, 'bar', 2]
  *    a1 = a << [3, 4]
  *    a1 # => [:foo, "bar", 2, [3, 4]]
+ *
  */
 
 VALUE
@@ -1263,7 +1485,7 @@ 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, {
-	RB_OBJ_WRITE(target_ary, &ptr[idx], item);
+        RB_OBJ_WRITE(target_ary, &ptr[idx], item);
     });
     ARY_SET_LEN(ary, idx + 1);
     ary_verify(ary);
@@ -1283,28 +1505,23 @@ rb_ary_cat(VALUE ary, const VALUE *argv, long len)
 /*
  *  call-seq:
  *    array.push(*objects) -> self
- *    array.append(*objects) -> self
- *
- *  Array#append is an alias for \Array#push.
  *
  *  Appends trailing elements.
  *
- *  See also:
- *  - #pop:  Removes and returns trailing elements.
- *  - #shift:  Removes and returns leading elements.
- *  - #unshift:  Prepends leading elements.
- *
  *  Appends each argument in +objects+ to +self+;  returns +self+:
+ *
  *    a = [:foo, 'bar', 2]
- *    a1 = a.push(:baz, :bat)
- *    a1 # => [:foo, "bar", 2, :baz, :bat]
- *    a1.equal?(a) # => true # Returned self
+ *    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]
  *    a1 = a.push([:baz, :bat], [:bam, :bad])
  *    a1 # => [:foo, "bar", 2, [:baz, :bat], [:bam, :bad]]
+ *
+ *  Array#append is an alias for Array#push.
+ *
+ *  Related: #pop, #shift, #unshift.
  */
 
 static VALUE
@@ -1321,10 +1538,10 @@ rb_ary_pop(VALUE ary)
     n = RARRAY_LEN(ary);
     if (n == 0) return Qnil;
     if (ARY_OWNS_HEAP_P(ary) &&
-	n * 3 < ARY_CAPA(ary) &&
-	ARY_CAPA(ary) > ARY_DEFAULT_SIZE)
+        n * 3 < ARY_CAPA(ary) &&
+        ARY_CAPA(ary) > ARY_DEFAULT_SIZE)
     {
-	ary_resize_capa(ary, n * 2);
+        ary_resize_capa(ary, n * 2);
     }
     --n;
     ARY_SET_LEN(ary, n);
@@ -1339,63 +1556,28 @@ rb_ary_pop(VALUE ary)
  *
  *  Removes and returns trailing elements.
  *
- *  See also:
- *  - #push:  Appends trailing elements.
- *  - #shift:  Removes and returns leading elements.
- *  - #unshift:  Prepends leading elements.
- *
- *  Argument +n+, if given, must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects]
- *  (implements +to_int+).
- *
- *  ---
- *
- *  When no argument is given and the array is not empty,
- *  removes and returns the last element in the array:
+ *  When no argument is given and +self+ is not empty,
+ *  removes and returns the last element:
  *
  *    a = [:foo, 'bar', 2]
  *    a.pop # => 2
  *    a # => [:foo, "bar"]
  *
- *  Returns +nil+ if the array is empty:
- *
- *    a = []
- *    a.pop # => nil
+ *  Returns +nil+ if the array is empty.
  *
- *  ---
- *
- *  When argument +n+ is given and is non-negative and in range,
+ *  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]
- *    a1 = a.pop(2)
- *    a1 # => ["bar", 2]
- *    a # => [:foo]
- *    a.pop(0) # => []
+ *    a.pop(2) # => ["bar", 2]
  *
  *  If +n+ is positive and out of range,
  *  removes and returns all elements:
  *
  *    a = [:foo, 'bar', 2]
- *    a1 = a.pop(50)
- *    a1 # => [:foo, "bar", 2]
- *    a # => []
- *    a.pop(1) # => []
- *
- *  ---
- *
- *  Raises an exception if +n+ is negative:
- *
- *    a = [:foo, 'bar', 2]
- *    # Raises ArgumentError (negative array size):
- *    a1 = a.pop(-1)
+ *    a.pop(50) # => [:foo, "bar", 2]
  *
- *  Raises an exception if +n+ is not \Integer-convertible (implements +to_int+):
- *
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of String into Integer):
- *    a1 = a.pop('x')
+ *  Related: #push, #shift, #unshift.
  */
 
 static VALUE
@@ -1404,7 +1586,7 @@ rb_ary_pop_m(int argc, VALUE *argv, VALUE ary)
     VALUE result;
 
     if (argc == 0) {
-	return rb_ary_pop(ary);
+        return rb_ary_pop(ary);
     }
 
     rb_ary_modify_check(ary);
@@ -1420,30 +1602,14 @@ rb_ary_shift(VALUE ary)
     VALUE top;
     long len = RARRAY_LEN(ary);
 
-    rb_ary_modify_check(ary);
-    if (len == 0) return Qnil;
-    top = RARRAY_AREF(ary, 0);
-    if (!ARY_SHARED_P(ary)) {
-	if (len < ARY_DEFAULT_SIZE) {
-            RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
-		MEMMOVE(ptr, ptr+1, VALUE, len-1);
-	    }); /* WB: no new reference */
-            ARY_INCREASE_LEN(ary, -1);
-            ary_verify(ary);
-	    return top;
-	}
-        assert(!ARY_EMBED_P(ary)); /* ARY_EMBED_LEN_MAX < ARY_DEFAULT_SIZE */
-
-	ARY_SET(ary, 0, Qnil);
-	ary_make_shared(ary);
-    }
-    else if (ARY_SHARED_ROOT_OCCUPIED(ARY_SHARED_ROOT(ary))) {
-        RARRAY_PTR_USE_TRANSIENT(ary, ptr, ptr[0] = Qnil);
+    if (len == 0) {
+        rb_ary_modify_check(ary);
+        return Qnil;
     }
-    ARY_INCREASE_PTR(ary, 1);		/* shift ptr */
-    ARY_INCREASE_LEN(ary, -1);
 
-    ary_verify(ary);
+    top = RARRAY_AREF(ary, 0);
+
+    rb_ary_behead(ary, 1);
 
     return top;
 }
@@ -1455,55 +1621,30 @@ rb_ary_shift(VALUE ary)
  *
  *  Removes and returns leading elements.
  *
- *  See also:
- *  - #push:  Appends trailing elements.
- *  - #pop:  Removes and returns trailing elements.
- *  - #unshift:  Prepends leading elements.
- *
- *  Argument +n+, if given, must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects]
- *
- *  ---
- *
  *  When no argument is given, removes and returns the first element:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.shift # => :foo
  *    a # => ['bar', 2]
  *
- *  Returns +nil+ if +self+ is empty:
- *    [].shift # => nil
- *
- *  ---
+ *  Returns +nil+ if +self+ is empty.
  *
- *  When argument +n+ is given, removes the first +n+ elements;
+ *  When positive \Integer argument +n+ is given, removes the first +n+ elements;
  *  returns those elements in a new \Array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.shift(2) # => [:foo, 'bar']
  *    a # => [2]
  *
  *  If +n+ is as large as or larger than <tt>self.length</tt>,
  *  removes all elements; returns those elements in a new \Array:
- *    a = [:foo, 'bar', 2]
- *    a.shift(3) # => [:foo, 'bar', 2]
- *    a # => []
  *
- *  If +n+ is zero, returns a new empty \Array; +self+ is unmodified:
  *    a = [:foo, 'bar', 2]
- *    a.shift(0) # => []
- *    a # => [:foo, 'bar', 2]
+ *    a.shift(3) # => [:foo, 'bar', 2]
  *
- *  ---
+ *  If +n+ is zero, returns a new empty \Array; +self+ is unmodified.
  *
- *  Raises an exception if +n+ is negative:
- *    a = [:foo, 'bar', 2]
- *    # Raises ArgumentError (negative array size):
- *    a1 = a.shift(-1)
- *
- *  Raises an exception if +n+ is not an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects]:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.shift(:foo)
+ *  Related: #push, #pop, #unshift.
  */
 
 static VALUE
@@ -1513,7 +1654,7 @@ rb_ary_shift_m(int argc, VALUE *argv, VALUE ary)
     long n;
 
     if (argc == 0) {
-	return rb_ary_shift(ary);
+        return rb_ary_shift(ary);
     }
 
     rb_ary_modify_check(ary);
@@ -1524,48 +1665,37 @@ rb_ary_shift_m(int argc, VALUE *argv, VALUE ary)
     return result;
 }
 
-static VALUE
-behead_shared(VALUE ary, long n)
-{
-    assert(ARY_SHARED_P(ary));
-    rb_ary_modify_check(ary);
-    if (ARY_SHARED_ROOT_OCCUPIED(ARY_SHARED_ROOT(ary))) {
-        ary_mem_clear(ary, 0, n);
-    }
-    ARY_INCREASE_PTR(ary, n);
-    ARY_INCREASE_LEN(ary, -n);
-    ary_verify(ary);
-    return ary;
-}
-
-static VALUE
-behead_transient(VALUE ary, long n)
-{
-    rb_ary_modify_check(ary);
-    RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
-        MEMMOVE(ptr, ptr+n, VALUE, RARRAY_LEN(ary)-n);
-    }); /* WB: no new reference */
-    ARY_INCREASE_LEN(ary, -n);
-    ary_verify(ary);
-    return ary;
-}
-
 MJIT_FUNC_EXPORTED VALUE
 rb_ary_behead(VALUE ary, long n)
 {
     if (n <= 0) {
         return ary;
     }
-    else if (ARY_SHARED_P(ary)) {
-        return behead_shared(ary, n);
-    }
-    else if (RARRAY_LEN(ary) >= ARY_DEFAULT_SIZE) {
+
+    rb_ary_modify_check(ary);
+
+    if (!ARY_SHARED_P(ary)) {
+        if (ARY_EMBED_P(ary) || RARRAY_LEN(ary) < ARY_DEFAULT_SIZE) {
+            RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
+                MEMMOVE(ptr, ptr + n, VALUE, RARRAY_LEN(ary) - n);
+            }); /* WB: no new reference */
+            ARY_INCREASE_LEN(ary, -n);
+            ary_verify(ary);
+            return ary;
+        }
+
+        ary_mem_clear(ary, 0, n);
         ary_make_shared(ary);
-        return behead_shared(ary, n);
     }
-    else {
-        return behead_transient(ary, n);
+    else if (ARY_SHARED_ROOT_OCCUPIED(ARY_SHARED_ROOT(ary))) {
+        ary_mem_clear(ary, 0, n);
     }
+
+    ARY_INCREASE_PTR(ary, n);
+    ARY_INCREASE_LEN(ary, -n);
+    ary_verify(ary);
+
+    return ary;
 }
 
 static VALUE
@@ -1596,28 +1726,28 @@ ary_modify_for_unshift(VALUE ary, int argc)
     rb_ary_modify(ary);
     capa = ARY_CAPA(ary);
     if (capa - (capa >> 6) <= new_len) {
-	ary_double_capa(ary, new_len);
+        ary_double_capa(ary, new_len);
     }
 
     /* use shared array for big "queues" */
-    if (new_len > ARY_DEFAULT_SIZE * 4) {
+    if (new_len > ARY_DEFAULT_SIZE * 4 && !ARY_EMBED_P(ary)) {
         ary_verify(ary);
 
         /* make a room for unshifted items */
-	capa = ARY_CAPA(ary);
-	ary_make_shared(ary);
+        capa = ARY_CAPA(ary);
+        ary_make_shared(ary);
 
         head = sharedp = RARRAY_CONST_PTR_TRANSIENT(ary);
         return make_room_for_unshift(ary, head, (void *)sharedp, argc, capa, len);
     }
     else {
-	/* sliding items */
+        /* sliding items */
         RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
-	    MEMMOVE(ptr + argc, ptr, VALUE, len);
-	});
+            MEMMOVE(ptr + argc, ptr, VALUE, len);
+        });
 
         ary_verify(ary);
-	return ary;
+        return ary;
     }
 }
 
@@ -1656,22 +1786,15 @@ ary_ensure_room_for_unshift(VALUE ary, int argc)
 /*
  *  call-seq:
  *    array.unshift(*objects) -> self
- *    array.prepend(*objects) -> self
  *
- *  Array#prepend is an alias for Array#unshift.
+ *  Prepends the given +objects+ to +self+:
  *
- *  Prepends leading elements.
+ *    a = [:foo, 'bar', 2]
+ *    a.unshift(:bam, :bat) # => [:bam, :bat, :foo, "bar", 2]
  *
- *  See also:
- *  - #push:  Appends trailing elements.
- *  - #pop:  Removes and returns trailing elements.
- *  - #shift:  Removes and returns leading elements.
+ *  Array#prepend is an alias for Array#unshift.
  *
- *  Prepends the given +objects+ to +self+:
- *    a = [:foo, 'bar', 2]
- *    a1 = a.unshift(:bam, :bat)
- *    a1 # => [:bam, :bat, :foo, "bar", 2]
- *    a1.equal?(a) # => true # Returned self
+ *  Related: #push, #pop, #shift.
  */
 
 static VALUE
@@ -1681,8 +1804,8 @@ rb_ary_unshift_m(int argc, VALUE *argv, VALUE ary)
     VALUE target_ary;
 
     if (argc == 0) {
-	rb_ary_modify_check(ary);
-	return ary;
+        rb_ary_modify_check(ary);
+        return ary;
     }
 
     target_ary = ary_ensure_room_for_unshift(ary, argc);
@@ -1704,7 +1827,7 @@ rb_ary_elt(VALUE ary, long offset)
     long len = RARRAY_LEN(ary);
     if (len == 0) return Qnil;
     if (offset < 0 || len <= offset) {
-	return Qnil;
+        return Qnil;
     }
     return RARRAY_AREF(ary, offset);
 }
@@ -1716,7 +1839,7 @@ rb_ary_entry(VALUE ary, long offset)
 }
 
 VALUE
-rb_ary_subseq(VALUE ary, long beg, long len)
+rb_ary_subseq_step(VALUE ary, long beg, long len, long step)
 {
     VALUE klass;
     long alen = RARRAY_LEN(ary);
@@ -1725,12 +1848,22 @@ rb_ary_subseq(VALUE ary, long beg, long len)
     if (beg < 0 || len < 0) return Qnil;
 
     if (alen < len || alen < beg + len) {
-	len = alen - beg;
+        len = alen - beg;
     }
-    klass = rb_obj_class(ary);
+    klass = rb_cArray;
     if (len == 0) return ary_new(klass, 0);
+    if (step == 0)
+        rb_raise(rb_eArgError, "slice step cannot be zero");
+    if (step == 1)
+        return ary_make_partial(ary, klass, beg, len);
+    else
+        return ary_make_partial_step(ary, klass, beg, len, step);
+}
 
-    return ary_make_partial(ary, klass, beg, len);
+VALUE
+rb_ary_subseq(VALUE ary, long beg, long len)
+{
+    return rb_ary_subseq_step(ary, beg, len, 1);
 }
 
 static VALUE rb_ary_aref2(VALUE ary, VALUE b, VALUE e);
@@ -1740,109 +1873,104 @@ static VALUE rb_ary_aref2(VALUE ary, VALUE b, VALUE e);
  *    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
  *
  *  Returns elements from +self+; does not modify +self+.
  *
- *  - Arguments +index+, +start+, and +length+, if given, must be
- *    {Integer-convertible objects}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *  - Argument +range+, if given, must be a \Range object.
- *
- *  ---
+ *  When a single \Integer argument +index+ is given, returns the element at offset +index+:
  *
- *  When a single argument +index+ is given, returns the element at offset +index+:
  *    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+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[-1] # => 2
  *    a[-2] # => "bar"
  *
- *  If +index+ is out of range, returns +nil+:
- *    a = [:foo, 'bar', 2]
- *    a[50] # => nil
- *    a[-50] # => nil
- *
- *  ---
+ *  If +index+ is out of range, returns +nil+.
  *
- *  When two arguments +start+ and +length+ are given,
+ *  When two \Integer arguments +start+ and +length+ are given,
  *  returns a new \Array of size +length+ containing successive elements beginning at offset +start+:
+ *
  *    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:
+ *
  *    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:
- *    a = [:foo, 'bar', 2]
- *    a[a.size, 0] # => []
- *    a[a.size, 50] # => []
+ *  returns a new empty \Array.
  *
- *  If +length+ is negative, returns +nil+:
- *    a = [:foo, 'bar', 2]
- *    a[2, -1] # => nil
- *    a[1, -2] # => nil
- *
- *  ---
+ *  If +length+ is negative, returns +nil+.
  *
- *  When a single argument +range+ is given,
+ *  When a single \Range argument +range+ is given,
  *  treats <tt>range.min</tt> as +start+ above
  *  and <tt>range.size</tt> as +length+ 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:
- *    a = [:foo, 'bar', 2]
- *    a[a.size..0] # => []
- *    a[a.size..50] # => []
- *    a[a.size..-1] # => []
- *    a[a.size..-50] # => []
+ *  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:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[0..-1] # => [:foo, "bar", 2]
  *    a[0..-2] # => [:foo, "bar"]
  *    a[0..-3] # => [:foo]
- *    a[0..-4] # => []
  *
  *  If <tt>range.start</tt> is negative, calculates the start index from the end:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[-1..2] # => [2]
  *    a[-2..2] # => ["bar", 2]
  *    a[-3..2] # => [:foo, "bar", 2]
  *
- *  If <tt>range.start</tt> is larger than the array size, returns +nil+:
+ *  If <tt>range.start</tt> is larger than the array size, returns +nil+.
+ *
  *    a = [:foo, 'bar', 2]
  *    a[4..1] # => nil
  *    a[4..0] # => nil
  *    a[4..-1] # => nil
  *
- *  ---
+ *  When a single Enumerator::ArithmeticSequence argument +aseq+ is given,
+ *  returns an \Array of elements corresponding to the indexes produced by
+ *  the sequence.
+ *
+ *    a = ['--', 'data1', '--', 'data2', '--', 'data3']
+ *    a[(1..).step(2)] # => ["data1", "data2", "data3"]
+ *
+ *  Unlike slicing with range, if the start or the end of the arithmetic sequence
+ *  is larger than array size, throws RangeError.
+ *
+ *    a = ['--', 'data1', '--', 'data2', '--', 'data3']
+ *    a[(1..11).step(2)]
+ *    # RangeError (((1..11).step(2)) out of range)
+ *    a[(7..).step(2)]
+ *    # RangeError (((7..).step(2)) out of range)
+ *
+ *  If given a single argument, and its type is not one of the listed, tries to
+ *  convert it to Integer, and raises if it is impossible:
  *
- *  Raises an exception if given a single argument
- *  that is not an \Integer-convertible object or a \Range object:
  *    a = [:foo, 'bar', 2]
  *    # Raises TypeError (no implicit conversion of Symbol into Integer):
  *    a[:foo]
  *
- *  Raises an exception if given two arguments that are not both \Integer-convertible objects:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a[:foo, 3]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a[1, :bar]
+ *  Array#slice is an alias for Array#[].
  */
 
 VALUE
@@ -1850,7 +1978,7 @@ rb_ary_aref(int argc, const VALUE *argv, VALUE ary)
 {
     rb_check_arity(argc, 1, 2);
     if (argc == 2) {
-	return rb_ary_aref2(ary, argv[0], argv[1]);
+        return rb_ary_aref2(ary, argv[0], argv[1]);
     }
     return rb_ary_aref1(ary, argv[0]);
 }
@@ -1861,7 +1989,7 @@ rb_ary_aref2(VALUE ary, VALUE b, VALUE e)
     long beg = NUM2LONG(b);
     long len = NUM2LONG(e);
     if (beg < 0) {
-	beg += RARRAY_LEN(ary);
+        beg += RARRAY_LEN(ary);
     }
     return rb_ary_subseq(ary, beg, len);
 }
@@ -1869,21 +1997,22 @@ rb_ary_aref2(VALUE ary, VALUE b, VALUE e)
 MJIT_FUNC_EXPORTED VALUE
 rb_ary_aref1(VALUE ary, VALUE arg)
 {
-    long beg, len;
+    long beg, len, step;
 
     /* special case - speeding up */
     if (FIXNUM_P(arg)) {
-	return rb_ary_entry(ary, FIX2LONG(arg));
+        return rb_ary_entry(ary, FIX2LONG(arg));
     }
-    /* check if idx is Range */
-    switch (rb_range_beg_len(arg, &beg, &len, RARRAY_LEN(ary), 0)) {
+    /* check if idx is Range or ArithmeticSequence */
+    switch (rb_arithmetic_sequence_beg_len_step(arg, &beg, &len, &step, RARRAY_LEN(ary), 0)) {
       case Qfalse:
-	break;
+        break;
       case Qnil:
-	return Qnil;
+        return Qnil;
       default:
-	return rb_ary_subseq(ary, beg, len);
+        return rb_ary_subseq_step(ary, beg, len, step);
     }
+
     return rb_ary_entry(ary, NUM2LONG(arg));
 }
 
@@ -1891,20 +2020,11 @@ rb_ary_aref1(VALUE ary, VALUE arg)
  *  call-seq:
  *    array.at(index) -> object
  *
- *  Argument +index+ must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *
- *  Returns the element at offset +index+; does not modify +self+.
+ *  Returns the element at \Integer offset +index+; does not modify +self+.
  *    a = [:foo, 'bar', 2]
  *    a.at(0) # => :foo
  *    a.at(2) # => 2
  *
- *  ---
- *
- *  Raises an exception if +index+ is not an \Integer-convertible object:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.at(:foo)
  */
 
 VALUE
@@ -1919,56 +2039,42 @@ rb_ary_at(VALUE ary, VALUE pos)
  *    array.first(n) -> new_array
  *
  *  Returns elements from +self+; does not modify +self+.
- *  See also #last.
- *
- *  Argument +n+, if given, must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *
- *  ---
  *
  *  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+:
- *    [].first # => nil
+ *  If +self+ is empty, returns +nil+.
  *
- *  ---
+ *  When non-negative \Integer argument +n+ is given,
+ *  returns the first +n+ elements in a new \Array:
  *
- *  When 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 >= ary.size</tt>, returns all elements:
+ *  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) # []
- *
- *  ---
  *
- *  Raises an exception if +n+ is negative:
  *    a = [:foo, 'bar', 2]
- *    # Raises ArgumentError (negative array size):
- *    a.first(-1)
+ *    a.first(0) # []
  *
- *  Raises an exception if +n+ is not an \Integer-convertible object:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of String into Integer):
- *    a.first(:X)
+ *  Related: #last.
  */
 static VALUE
 rb_ary_first(int argc, VALUE *argv, VALUE ary)
 {
     if (argc == 0) {
-	if (RARRAY_LEN(ary) == 0) return Qnil;
-	return RARRAY_AREF(ary, 0);
+        if (RARRAY_LEN(ary) == 0) return Qnil;
+        return RARRAY_AREF(ary, 0);
     }
     else {
-	return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST);
+        return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST);
     }
 }
 
@@ -1978,58 +2084,44 @@ rb_ary_first(int argc, VALUE *argv, VALUE ary)
  *    array.last(n) -> new_array
  *
  *  Returns elements from +self+; +self+ is not modified.
- *  See also #first.
- *
- *  Argument +n+, if given, must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *
- *  ---
  *
  *  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+:
- *    [].last # => nil
+ *  If +self+ is empty, returns +nil+.
  *
- *  ---
+ *  When non-negative \Integer argument +n+ is given,
+ *  returns the last +n+ elements in a new \Array:
  *
- *  When 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 >= ary.size</tt>, returns all elements:
+ *  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) # []
  *
- *  ---
- *
- *  Raises an exception if +n+ is negative:
  *    a = [:foo, 'bar', 2]
- *    # Raises ArgumentError (negative array size):
- *    a.last(-1)
+ *    a.last(0) # []
  *
- *  Raises an exception if +n+ is not an \Integer-convertible object:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.last(:X)
+ *  Related: #first.
  */
 
 VALUE
 rb_ary_last(int argc, const VALUE *argv, VALUE ary)
 {
     if (argc == 0) {
-	long len = RARRAY_LEN(ary);
-	if (len == 0) return Qnil;
-	return RARRAY_AREF(ary, len-1);
+        long len = RARRAY_LEN(ary);
+        if (len == 0) return Qnil;
+        return RARRAY_AREF(ary, len-1);
     }
     else {
-	return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_LAST);
+        return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_LAST);
     }
 }
 
@@ -2041,50 +2133,33 @@ rb_ary_last(int argc, const VALUE *argv, VALUE ary)
  *
  *  Returns the element at offset  +index+.
  *
- *  Argument +index+ must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects]
+ *  With the single \Integer argument +index+,
+ *  returns the element at offset +index+:
  *
- *  ---
- *
- *  With the single argument +index+, returns the element at offset +index+:
  *    a = [:foo, 'bar', 2]
  *    a.fetch(1) # => "bar"
  *
  *  If +index+ is negative, counts from the end of the array:
+ *
  *    a = [:foo, 'bar', 2]
  *    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+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.fetch(1, nil) # => "bar"
- *    a.fetch(50, nil) # => nil
- *
- *  ---
  *
  *  With argument +index+ and a block,
  *  returns the element at offset +index+ if index is in range
  *  (and the block is not called); otherwise calls the block with index and returns its return value:
  *
  *    a = [:foo, 'bar', 2]
- *    a.fetch(1) { |index| raise 'Cannot happen' } # => "bar"
- *    a.fetch(50) { |index| "Value for #{index}" } # => "Value for 50"
+ *    a.fetch(1) {|index| raise 'Cannot happen' } # => "bar"
+ *    a.fetch(50) {|index| "Value for #{index}" } # => "Value for 50"
  *
- *  ---
- *
- *  Raises an exception if +index+ is not an \Integer-convertible object.
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.fetch(:foo)
- *
- *  Raises an exception if +index+ is out of range and neither default_value nor a block given:
- *    a = [:foo, 'bar', 2]
- *    # Raises IndexError (index 50 outside of array bounds: -3...3):
- *    a.fetch(50)
  */
 
 static VALUE
@@ -2097,20 +2172,20 @@ rb_ary_fetch(int argc, VALUE *argv, VALUE ary)
     rb_scan_args(argc, argv, "11", &pos, &ifnone);
     block_given = rb_block_given_p();
     if (block_given && argc == 2) {
-	rb_warn("block supersedes default value argument");
+        rb_warn("block supersedes default value argument");
     }
     idx = NUM2LONG(pos);
 
     if (idx < 0) {
-	idx +=  RARRAY_LEN(ary);
+        idx +=  RARRAY_LEN(ary);
     }
     if (idx < 0 || RARRAY_LEN(ary) <= idx) {
-	if (block_given) return rb_yield(pos);
-	if (argc == 1) {
-	    rb_raise(rb_eIndexError, "index %ld outside of array bounds: %ld...%ld",
-			idx - (idx < 0 ? RARRAY_LEN(ary) : 0), -RARRAY_LEN(ary), RARRAY_LEN(ary));
-	}
-	return ifnone;
+        if (block_given) return rb_yield(pos);
+        if (argc == 1) {
+            rb_raise(rb_eIndexError, "index %ld outside of array bounds: %ld...%ld",
+                        idx - (idx < 0 ? RARRAY_LEN(ary) : 0), -RARRAY_LEN(ary), RARRAY_LEN(ary));
+        }
+        return ifnone;
     }
     return RARRAY_AREF(ary, idx);
 }
@@ -2120,54 +2195,37 @@ rb_ary_fetch(int argc, VALUE *argv, VALUE ary)
  *    array.index(object) -> integer or nil
  *    array.index {|element| ... } -> integer or nil
  *    array.index -> new_enumerator
- *    array.find_index(object) -> integer or nil
- *    array.find_index {|element| ... } -> integer or nil
- *    array.find_index -> new_enumerator
- *
- *  Array#find_index is an alias for Array#index.
- *  See also Array#rindex.
  *
  *  Returns the index of a specified element.
  *
- *  ---
- *
  *  When argument +object+ is given but no block,
  *  returns the index of the first element +element+
  *  for which <tt>object == element</tt>:
+ *
  *    a = [:foo, 'bar', 2, 'bar']
  *    a.index('bar') # => 1
  *
- *  Returns +nil+ if no such element found:
- *    a = [:foo, 'bar', 2]
- *    a.index(:nosuch) # => nil
- *
- *  ---
+ *  Returns +nil+ if no such element found.
  *
  *  When both argument +object+ and a block are given,
  *  calls the block with each successive element;
  *  returns the index of the first element for which the block returns a truthy value:
- *    a = [:foo, 'bar', 2, 'bar']
- *    a.index { |element| element == 'bar' } # => 1
  *
- *  Returns +nil+ if the block never returns a truthy value:
- *    a = [:foo, 'bar', 2]
- *    a.index { |element| element == :X } # => nil
+ *    a = [:foo, 'bar', 2, 'bar']
+ *    a.index {|element| element == 'bar' } # => 1
  *
- *  ---
+ *  Returns +nil+ if the block never returns a truthy value.
  *
  *  When neither an argument nor a block is given, returns a new Enumerator:
+ *
  *    a = [:foo, 'bar', 2]
  *    e = a.index
  *    e # => #<Enumerator: [:foo, "bar", 2]:index>
- *    e.each { |element| element == 'bar' } # => 1
+ *    e.each {|element| element == 'bar' } # => 1
  *
- *  ---
+ *  Array#find_index is an alias for Array#index.
  *
- *  When both an argument and a block given, gives a warning (warning: given block not used)
- *  and ignores the block:
- *    a = [:foo, 'bar', 2, 'bar']
- *    index = a.index('bar') { raise 'Cannot happen' }
- *    index # => 1
+ *  Related: #rindex.
  */
 
 static VALUE
@@ -2177,23 +2235,23 @@ rb_ary_index(int argc, VALUE *argv, VALUE ary)
     long i;
 
     if (argc == 0) {
-	RETURN_ENUMERATOR(ary, 0, 0);
-	for (i=0; i<RARRAY_LEN(ary); i++) {
-	    if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) {
-		return LONG2NUM(i);
-	    }
-	}
-	return Qnil;
+        RETURN_ENUMERATOR(ary, 0, 0);
+        for (i=0; i<RARRAY_LEN(ary); i++) {
+            if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) {
+                return LONG2NUM(i);
+            }
+        }
+        return Qnil;
     }
     rb_check_arity(argc, 0, 1);
     val = argv[0];
     if (rb_block_given_p())
-	rb_warn("given block not used");
+        rb_warn("given block not used");
     for (i=0; i<RARRAY_LEN(ary); i++) {
-	VALUE e = RARRAY_AREF(ary, i);
-	if (rb_equal(e, val)) {
-	    return LONG2NUM(i);
-	}
+        VALUE e = RARRAY_AREF(ary, i);
+        if (rb_equal(e, val)) {
+            return LONG2NUM(i);
+        }
     }
     return Qnil;
 }
@@ -2206,44 +2264,29 @@ rb_ary_index(int argc, VALUE *argv, VALUE ary)
  *
  *  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:
+ *
  *    a = [:foo, 'bar', 2, 'bar']
  *    a.rindex('bar') # => 3
  *
- *  Returns +nil+ if no such object found:
- *    a = [:foo, 'bar', 2]
- *    a.rindex(:nosuch) # => nil
- *
- *  ---
+ *  Returns +nil+ if no such object found.
  *
  *  When a block is given but no argument, 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']
  *    a.rindex {|element| element == 'bar' } # => 3
  *
- *  Returns +nil+ if the block never returns a truthy value:
- *
- *    a = [:foo, 'bar', 2]
- *    a.rindex {|element| element == :X } # => nil
- *
- *  ---
+ *  Returns +nil+ if the block never returns a truthy value.
  *
  *  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
+ *    e.each {|element| element == 'bar' } # => 3
  *
- *  ---
- *
- *  When both an argument and a block given, gives a warning (warning: given block not used)
- *  and ignores the block:
- *    a = [:foo, 'bar', 2, 'bar']
- *    index = a.rindex('bar') { raise 'Cannot happen' }
- *    index # => 3
+ *  Related: #index.
  */
 
 static VALUE
@@ -2253,25 +2296,25 @@ rb_ary_rindex(int argc, VALUE *argv, VALUE ary)
     long i = RARRAY_LEN(ary), len;
 
     if (argc == 0) {
-	RETURN_ENUMERATOR(ary, 0, 0);
-	while (i--) {
-	    if (RTEST(rb_yield(RARRAY_AREF(ary, i))))
-		return LONG2NUM(i);
-	    if (i > (len = RARRAY_LEN(ary))) {
-		i = len;
-	    }
-	}
-	return Qnil;
+        RETURN_ENUMERATOR(ary, 0, 0);
+        while (i--) {
+            if (RTEST(rb_yield(RARRAY_AREF(ary, i))))
+                return LONG2NUM(i);
+            if (i > (len = RARRAY_LEN(ary))) {
+                i = len;
+            }
+        }
+        return Qnil;
     }
     rb_check_arity(argc, 0, 1);
     val = argv[0];
     if (rb_block_given_p())
-	rb_warn("given block not used");
+        rb_warn("given block not used");
     while (i--) {
-	VALUE e = RARRAY_AREF(ary, i);
-	if (rb_equal(e, val)) {
-	    return LONG2NUM(i);
-	}
+        VALUE e = RARRAY_AREF(ary, i);
+        if (rb_equal(e, val)) {
+            return LONG2NUM(i);
+        }
         if (i > RARRAY_LEN(ary)) {
             break;
         }
@@ -2297,54 +2340,54 @@ rb_ary_splice(VALUE ary, long beg, long len, const VALUE *rptr, long rlen)
     if (len < 0) rb_raise(rb_eIndexError, "negative length (%ld)", len);
     olen = RARRAY_LEN(ary);
     if (beg < 0) {
-	beg += olen;
-	if (beg < 0) {
-	    rb_raise(rb_eIndexError, "index %ld too small for array; minimum: %ld",
-		     beg - olen, -olen);
-	}
+        beg += olen;
+        if (beg < 0) {
+            rb_raise(rb_eIndexError, "index %ld too small for array; minimum: %ld",
+                     beg - olen, -olen);
+        }
     }
     if (olen < len || olen < beg + len) {
-	len = olen - beg;
+        len = olen - beg;
     }
 
     {
         const VALUE *optr = RARRAY_CONST_PTR_TRANSIENT(ary);
-	rofs = (rptr >= optr && rptr < optr + olen) ? rptr - optr : -1;
+        rofs = (rptr >= optr && rptr < optr + olen) ? rptr - optr : -1;
     }
 
     if (beg >= olen) {
-	VALUE target_ary;
-	if (beg > ARY_MAX_SIZE - rlen) {
-	    rb_raise(rb_eIndexError, "index %ld too big", beg);
-	}
-	target_ary = ary_ensure_room_for_push(ary, rlen-len); /* len is 0 or negative */
-	len = beg + rlen;
-	ary_mem_clear(ary, olen, beg - olen);
-	if (rlen > 0) {
+        VALUE target_ary;
+        if (beg > ARY_MAX_SIZE - rlen) {
+            rb_raise(rb_eIndexError, "index %ld too big", beg);
+        }
+        target_ary = ary_ensure_room_for_push(ary, rlen-len); /* len is 0 or negative */
+        len = beg + rlen;
+        ary_mem_clear(ary, olen, beg - olen);
+        if (rlen > 0) {
             if (rofs != -1) rptr = RARRAY_CONST_PTR_TRANSIENT(ary) + rofs;
-	    ary_memcpy0(ary, beg, rlen, rptr, target_ary);
-	}
-	ARY_SET_LEN(ary, len);
+            ary_memcpy0(ary, beg, rlen, rptr, target_ary);
+        }
+        ARY_SET_LEN(ary, len);
     }
     else {
-	long alen;
-
-	if (olen - len > ARY_MAX_SIZE - rlen) {
-	    rb_raise(rb_eIndexError, "index %ld too big", olen + rlen - len);
-	}
-	rb_ary_modify(ary);
-	alen = olen + rlen - len;
-	if (alen >= ARY_CAPA(ary)) {
-	    ary_double_capa(ary, alen);
-	}
-
-	if (len != rlen) {
+        long alen;
+
+        if (olen - len > ARY_MAX_SIZE - rlen) {
+            rb_raise(rb_eIndexError, "index %ld too big", olen + rlen - len);
+        }
+        rb_ary_modify(ary);
+        alen = olen + rlen - len;
+        if (alen >= ARY_CAPA(ary)) {
+            ary_double_capa(ary, alen);
+        }
+
+        if (len != rlen) {
             RARRAY_PTR_USE_TRANSIENT(ary, ptr,
                                      MEMMOVE(ptr + beg + rlen, ptr + beg + len,
                                              VALUE, olen - (beg + len)));
-	    ARY_SET_LEN(ary, alen);
-	}
-	if (rlen > 0) {
+            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);
@@ -2354,7 +2397,7 @@ rb_ary_splice(VALUE ary, long beg, long len, const VALUE *rptr, long rlen)
              */
             RARRAY_PTR_USE_TRANSIENT(ary, ptr,
                                      MEMMOVE(ptr + beg, rptr, VALUE, rlen));
-	}
+        }
     }
 }
 
@@ -2365,22 +2408,14 @@ rb_ary_set_len(VALUE ary, long len)
 
     rb_ary_modify_check(ary);
     if (ARY_SHARED_P(ary)) {
-	rb_raise(rb_eRuntimeError, "can't set length of shared ");
+        rb_raise(rb_eRuntimeError, "can't set length of shared ");
     }
     if (len > (capa = (long)ARY_CAPA(ary))) {
-	rb_bug("probable buffer overflow: %ld for %ld", len, capa);
+        rb_bug("probable buffer overflow: %ld for %ld", len, capa);
     }
     ARY_SET_LEN(ary, len);
 }
 
-/*!
- * expands or shrinks \a ary to \a len elements.
- * expanded region will be filled with Qnil.
- * \param ary  an array
- * \param len  new size
- * \return     \a ary
- * \post       the size of \a ary is \a len.
- */
 VALUE
 rb_ary_resize(VALUE ary, long len)
 {
@@ -2390,31 +2425,37 @@ rb_ary_resize(VALUE ary, long len)
     olen = RARRAY_LEN(ary);
     if (len == olen) return ary;
     if (len > ARY_MAX_SIZE) {
-	rb_raise(rb_eIndexError, "index %ld too big", len);
+        rb_raise(rb_eIndexError, "index %ld too big", len);
     }
     if (len > olen) {
-	if (len >= ARY_CAPA(ary)) {
-	    ary_double_capa(ary, len);
-	}
-	ary_mem_clear(ary, olen, len - olen);
-	ARY_SET_LEN(ary, len);
+        if (len >= ARY_CAPA(ary)) {
+            ary_double_capa(ary, len);
+        }
+        ary_mem_clear(ary, olen, len - olen);
+        ARY_SET_LEN(ary, len);
     }
     else if (ARY_EMBED_P(ary)) {
         ARY_SET_EMBED_LEN(ary, len);
     }
-    else if (len <= RARRAY_EMBED_LEN_MAX) {
-	VALUE tmp[RARRAY_EMBED_LEN_MAX];
-	MEMCPY(tmp, ARY_HEAP_PTR(ary), VALUE, len);
-	ary_discard(ary);
-	MEMCPY((VALUE *)ARY_EMBED_PTR(ary), tmp, VALUE, len); /* WB: no new reference */
+    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);
+
+        FL_UNSET(ary, RARRAY_TRANSIENT_FLAG);
+        FL_SET_EMBED(ary);
+
+        MEMCPY((VALUE *)ARY_EMBED_PTR(ary), ptr, VALUE, len); /* WB: no new reference */
         ARY_SET_EMBED_LEN(ary, len);
+
+        if (is_malloc_ptr) ruby_sized_xfree((void *)ptr, ptr_capa);
     }
     else {
-	if (olen > len + ARY_DEFAULT_SIZE) {
-            ary_heap_realloc(ary, len);
-	    ARY_SET_CAPA(ary, len);
-	}
-	ARY_SET_HEAP_LEN(ary, len);
+        if (olen > len + ARY_DEFAULT_SIZE) {
+            size_t new_capa = ary_heap_realloc(ary, len);
+            ARY_SET_CAPA(ary, new_capa);
+        }
+        ARY_SET_HEAP_LEN(ary, len);
     }
     ary_verify(ary);
     return ary;
@@ -2444,42 +2485,36 @@ ary_aset_by_rb_ary_splice(VALUE ary, long beg, long len, VALUE val)
  *
  *  Assigns elements in +self+; returns the given +object+.
  *
- *  - Arguments +index+, +start+, and +length+, if given, must be
- *    {Integer-convertible objects}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *  - Argument +range+, if given, must be a \Range object.
- *  - If +object+ is an
- *    {Array-convertible object}[doc/implicit_conversion_rdoc.html#label-Array-Convertible+Objects]
- *    it will be converted to an \Array.
- *
- *  ---
- *
- *  When +index+ is given, assigns +object+ to an element in +self+.
+ *  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+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[0] = 'foo' # => "foo"
  *    a # => ["foo", "bar", 2]
  *
  *  If +index+ is greater than <tt>self.length</tt>, extends the array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[7] = 'foo' # => "foo"
  *    a # => [:foo, "bar", 2, nil, nil, nil, nil, "foo"]
  *
  *  If +index+ is negative, counts backwards from the end of the array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[-1] = 'two' # => "two"
  *    a # => [:foo, "bar", "two"]
  *
- *  ---
- *
- *  When +start+ and +length+ are given and +object+ is not an Array-convertible object,
+ *  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+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[0, 2] = 'foo' # => "foo"
  *    a # => ["foo", 2]
  *
  *  If +start+ is negative, counts backwards from the end of the array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[-2, 2] = 'foo' # => "foo"
  *    a # => [:foo, "foo"]
@@ -2487,49 +2522,55 @@ ary_aset_by_rb_ary_splice(VALUE ary, long beg, long len, VALUE val)
  *  If +start+ is non-negative and outside the array (<tt> >= self.size</tt>),
  *  extends the array with +nil+, assigns +object+ at offset +start+,
  *  and ignores +length+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[6, 50] = 'foo' # => "foo"
  *    a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
  *
  *  If +length+ is zero, shifts elements at and following offset +start+
  *  and assigns +object+ at offset +start+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[1, 0] = 'foo' # => "foo"
  *    a # => [:foo, "foo", "bar", 2]
  *
  *  If +length+ is too large for the existing array, does not extend the array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[1, 5] = 'foo' # => "foo"
  *    a # => [:foo, "foo"]
  *
- *  ---
- *
- *  When +range+ is given and +object+ is an \Array-convertible object,
+ *  When \Range argument +range+ is given and +object+ is an \Array,
  *  removes <tt>length - 1</tt> elements beginning at offset +start+,
  *  and assigns +object+ at offset +start+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[0..1] = 'foo' # => "foo"
  *    a # => ["foo", 2]
  *
  *  if <tt>range.begin</tt> is negative, counts backwards from the end of the array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[-2..2] = 'foo' # => "foo"
  *    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+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[6..50] = 'foo' # => "foo"
  *    a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
  *
  *  If <tt>range.end</tt> is zero, shifts elements at and following offset +start+
  *  and assigns +object+ at offset +start+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[1..0] = 'foo' # => "foo"
  *    a # => [:foo, "foo", "bar", 2]
  *
  *  If <tt>range.end</tt> is negative, assigns +object+ at offset +start+,
  *  retains <tt>range.end.abs -1</tt> elements past that, and removes those beyond:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[1..-1] = 'foo' # => "foo"
  *    a # => [:foo, "foo"]
@@ -2543,39 +2584,11 @@ ary_aset_by_rb_ary_splice(VALUE ary, long beg, long len, VALUE val)
  *
  *  If <tt>range.end</tt> is too large for the existing array,
  *  replaces array elements, but does not extend the array with +nil+ values:
+ *
  *    a = [:foo, 'bar', 2]
  *    a[1..5] = 'foo' # => "foo"
  *    a # => [:foo, "foo"]
  *
- *  ---
- *
- *  Raises an exception if given a single argument
- *  that is not an \Integer-convertible object or a \Range:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a[:nosuch] = 'two'
- *
- *  Raises an exception if given two arguments that are not both \Integer-convertible objects:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a[:nosuch, 2] = 'two'
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a[0, :nosuch] = 'two'
- *
- *  Raises an exception if a negative +index+ is out of range:
- *    a = [:foo, 'bar', 2]
- *    # Raises IndexError (index -4 too small for array; minimum: -3):
- *    a[-4] = 'two'
- *
- *  Raises an exception if +start+ is too small for the array:
- *    a = [:foo, 'bar', 2]
- *    # Raises IndexError (index -5 too small for array; minimum: -3):
- *    a[-5, 2] = 'foo'
- *
- *  Raises an exception if +length+ is negative:
- *    a = [:foo, 'bar', 2]
- *    # Raises IndexError (negative length (-1)):
- *    a[1, -1] = 'foo'
  */
 
 static VALUE
@@ -2586,16 +2599,16 @@ rb_ary_aset(int argc, VALUE *argv, VALUE ary)
     rb_check_arity(argc, 2, 3);
     rb_ary_modify_check(ary);
     if (argc == 3) {
-	beg = NUM2LONG(argv[0]);
-	len = NUM2LONG(argv[1]);
+        beg = NUM2LONG(argv[0]);
+        len = NUM2LONG(argv[1]);
         return ary_aset_by_rb_ary_splice(ary, beg, len, argv[2]);
     }
     if (FIXNUM_P(argv[0])) {
-	offset = FIX2LONG(argv[0]);
+        offset = FIX2LONG(argv[0]);
         return ary_aset_by_rb_ary_store(ary, offset, argv[1]);
     }
     if (rb_range_beg_len(argv[0], &beg, &len, RARRAY_LEN(ary), 1)) {
-	/* check if idx is Range */
+        /* check if idx is Range */
         return ary_aset_by_rb_ary_splice(ary, beg, len, argv[1]);
     }
 
@@ -2607,52 +2620,36 @@ rb_ary_aset(int argc, VALUE *argv, VALUE ary)
  *  call-seq:
  *    array.insert(index, *objects) -> self
  *
- *  Inserts given +objects+ before or after the element at +offset+ index;
+ *  Inserts given +objects+ before or after the element at \Integer index +offset+;
  *  returns +self+.
  *
- *  Argument +index+ must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *
- *  ---
- *
  *  When +index+ is non-negative, inserts all given +objects+
  *  before the element at offset +index+:
+ *
  *    a = [:foo, 'bar', 2]
- *    a1 = a.insert(1, :bat, :bam)
- *    a # => [:foo, :bat, :bam, "bar", 2]
- *    a1.object_id == a.object_id # => true
+ *    a.insert(1, :bat, :bam) # => [:foo, :bat, :bam, "bar", 2]
  *
  *  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]
  *
  *  Does nothing if no objects given:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.insert(1)
  *    a.insert(50)
  *    a.insert(-50)
  *    a # => [:foo, "bar", 2]
  *
- *  ---
- *
  *  When +index+ is negative, inserts all given +objects+
  *  _after_ the element at offset <tt>index+self.size</tt>:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.insert(-2, :bat, :bam)
  *    a # => [:foo, "bar", :bat, :bam, 2]
  *
- *  ---
- *
- *  Raises an exception if +index+ is not an Integer-convertible object:
- *    a = [:foo, 'bar', 2, 'bar']
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.insert(:foo)
- *
- *  Raises an exception if +index+ is too small (<tt>index+self.size < 0</tt>):
- *    a = [:foo, 'bar', 2]
- *    # Raises IndexError (index -5 too small for array; minimum: -4):
- *    a.insert(-5, :bat, :bam)
  */
 
 static VALUE
@@ -2665,15 +2662,15 @@ rb_ary_insert(int argc, VALUE *argv, VALUE ary)
     pos = NUM2LONG(argv[0]);
     if (argc == 1) return ary;
     if (pos == -1) {
-	pos = RARRAY_LEN(ary);
+        pos = RARRAY_LEN(ary);
     }
     else if (pos < 0) {
-	long minpos = -RARRAY_LEN(ary) - 1;
-	if (pos < minpos) {
-	    rb_raise(rb_eIndexError, "index %ld too small for array; minimum: %ld",
-		     pos, minpos);
-	}
-	pos++;
+        long minpos = -RARRAY_LEN(ary) - 1;
+        if (pos < minpos) {
+            rb_raise(rb_eIndexError, "index %ld too small for array; minimum: %ld",
+                     pos, minpos);
+        }
+        pos++;
     }
     rb_ary_splice(ary, pos, 0, argv + 1, argc - 1);
     return ary;
@@ -2695,40 +2692,42 @@ ary_enum_length(VALUE ary, VALUE args, VALUE eobj)
  *
  *  Iterates over array elements.
  *
- *  ---
- *
  *  When a block given, passes each successive array element to the block;
  *  returns +self+:
+ *
  *    a = [:foo, 'bar', 2]
- *    a1 = a.each {|element|  puts "#{element.class} #{element}" }
- *    a1.equal?(a) # => true # Returned self
+ *    a.each {|element|  puts "#{element.class} #{element}" }
  *
  *  Output:
+ *
  *    Symbol foo
  *    String bar
  *    Integer 2
  *
  *  Allows the array to be modified during iteration:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.each {|element| puts element; a.clear if element.to_s.start_with?('b') }
- *    a # => []
  *
  *  Output:
+ *
  *    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}" }
+ *    a1 = e.each {|element|  puts "#{element.class} #{element}" }
  *
  *  Output:
+ *
  *    Symbol foo
  *    String bar
  *    Integer 2
+ *
+ *  Related: #each_index, #reverse_each.
  */
 
 VALUE
@@ -2738,7 +2737,7 @@ rb_ary_each(VALUE ary)
     ary_verify(ary);
     RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
     for (i=0; i<RARRAY_LEN(ary); i++) {
-	rb_yield(RARRAY_AREF(ary, i));
+        rb_yield(RARRAY_AREF(ary, i));
     }
     return ary;
 }
@@ -2750,40 +2749,42 @@ rb_ary_each(VALUE ary)
  *
  *  Iterates over array indexes.
  *
- *  ---
- *
  *  When a block given, passes each successive array index to the block;
  *  returns +self+:
+ *
  *    a = [:foo, 'bar', 2]
- *    a1 = a.each_index {|index|  puts "#{index} #{a[index]}" }
- *    a1.equal?(a) # => true # Returned self
+ *    a.each_index {|index|  puts "#{index} #{a[index]}" }
  *
  *  Output:
+ *
  *    0 foo
  *    1 bar
  *    2 2
  *
  *  Allows the array to be modified during iteration:
+ *
  *    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:
+ *
  *    0 foo
  *    1 bar
  *    2 2
+ *
+ *  Related: #each, #reverse_each.
  */
 
 static VALUE
@@ -2793,7 +2794,7 @@ rb_ary_each_index(VALUE ary)
     RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
 
     for (i=0; i<RARRAY_LEN(ary); i++) {
-	rb_yield(LONG2NUM(i));
+        rb_yield(LONG2NUM(i));
     }
     return ary;
 }
@@ -2805,39 +2806,42 @@ rb_ary_each_index(VALUE ary)
  *
  *  Iterates backwards over array elements.
  *
- *  ---
- *
  *  When a block given, passes, in reverse order, each element to the block;
  *  returns +self+:
+ *
  *    a = [:foo, 'bar', 2]
- *    a1 = a.reverse_each {|element|  puts "#{element.class} #{element}" }
- *    a1.equal?(a) # => true # Returned self
+ *    a.reverse_each {|element|  puts "#{element.class} #{element}" }
  *
  *  Output:
+ *
  *    Integer 2
  *    String bar
  *    Symbol foo
  *
  *  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') }
- *    a # => []
  *
  *  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}" }
+ *    a1 = e.each {|element|  puts "#{element.class} #{element}" }
+ *
  *  Output:
+ *
  *    Integer 2
  *    String bar
  *    Symbol foo
+ *
+ *  Related: #each, #each_index.
  */
 
 static VALUE
@@ -2848,12 +2852,12 @@ rb_ary_reverse_each(VALUE ary)
     RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
     len = RARRAY_LEN(ary);
     while (len--) {
-	long nlen;
-	rb_yield(RARRAY_AREF(ary, len));
-	nlen = RARRAY_LEN(ary);
-	if (nlen < len) {
-	    len = nlen;
-	}
+        long nlen;
+        rb_yield(RARRAY_AREF(ary, len));
+        nlen = RARRAY_LEN(ary);
+        if (nlen < len) {
+            len = nlen;
+        }
     }
     return ary;
 }
@@ -2862,10 +2866,7 @@ rb_ary_reverse_each(VALUE ary)
  *  call-seq:
  *    array.length -> an_integer
  *
- *  Returns the count of elements in the array:
- *    a = [:foo, 'bar', 2]
- *    a.length # => 3
- *    [].length # => 0
+ *  Returns the count of elements in +self+.
  */
 
 static VALUE
@@ -2879,18 +2880,14 @@ rb_ary_length(VALUE ary)
  *  call-seq:
  *    array.empty?  -> true or false
  *
- *  Returns +true+ if the count of elements in the array is zero,
- *  +false+ otherwise:
- *    [].empty? # => true
- *    [:foo, 'bar', 2].empty? # => false
+ *  Returns +true+ if the count of elements in +self+ is zero,
+ *  +false+ otherwise.
  */
 
 static VALUE
 rb_ary_empty_p(VALUE ary)
 {
-    if (RARRAY_LEN(ary) == 0)
-	return Qtrue;
-    return Qfalse;
+    return RBOOL(RARRAY_LEN(ary) == 0);
 }
 
 VALUE
@@ -2926,10 +2923,10 @@ recursive_join(VALUE obj, VALUE argp, int recur)
     int *first = (int *)arg[3];
 
     if (recur) {
-	rb_raise(rb_eArgError, "recursive array join");
+        rb_raise(rb_eArgError, "recursive array join");
     }
     else {
-	ary_join_1(obj, ary, sep, 0, result, first);
+        ary_join_1(obj, ary, sep, 0, result, first);
     }
     return Qnil;
 }
@@ -2942,11 +2939,11 @@ ary_join_0(VALUE ary, VALUE sep, long max, VALUE result)
 
     if (max > 0) rb_enc_copy(result, RARRAY_AREF(ary, 0));
     for (i=0; i<max; i++) {
-	val = RARRAY_AREF(ary, i);
+        val = RARRAY_AREF(ary, i);
         if (!RB_TYPE_P(val, T_STRING)) break;
-	if (i > 0 && !NIL_P(sep))
-	    rb_str_buf_append(result, sep);
-	rb_str_buf_append(result, val);
+        if (i > 0 && !NIL_P(sep))
+            rb_str_buf_append(result, sep);
+        rb_str_buf_append(result, val);
     }
     return i;
 }
@@ -2985,16 +2982,16 @@ ary_join_1(VALUE obj, VALUE ary, VALUE sep, long i, VALUE result, int *first)
     VALUE val, tmp;
 
     for (; i<RARRAY_LEN(ary); i++) {
-	if (i > 0 && !NIL_P(sep))
-	    rb_str_buf_append(result, sep);
+        if (i > 0 && !NIL_P(sep))
+            rb_str_buf_append(result, sep);
 
-	val = RARRAY_AREF(ary, i);
-	if (RB_TYPE_P(val, T_STRING)) {
+        val = RARRAY_AREF(ary, i);
+        if (RB_TYPE_P(val, T_STRING)) {
             ary_join_1_str(result, val, first);
-	}
-	else if (RB_TYPE_P(val, T_ARRAY)) {
+        }
+        else if (RB_TYPE_P(val, T_ARRAY)) {
             ary_join_1_ary(val, ary, sep, result, val, first);
-	}
+        }
         else if (!NIL_P(tmp = rb_check_string_type(val))) {
             ary_join_1_str(result, tmp, first);
         }
@@ -3003,7 +3000,7 @@ ary_join_1(VALUE obj, VALUE ary, VALUE sep, long i, VALUE result, int *first)
         }
         else {
             ary_join_1_str(result, rb_obj_as_string(val), first);
-	}
+        }
     }
 }
 
@@ -3016,26 +3013,26 @@ rb_ary_join(VALUE ary, VALUE sep)
     if (RARRAY_LEN(ary) == 0) return rb_usascii_str_new(0, 0);
 
     if (!NIL_P(sep)) {
-	StringValue(sep);
-	len += RSTRING_LEN(sep) * (RARRAY_LEN(ary) - 1);
+        StringValue(sep);
+        len += RSTRING_LEN(sep) * (RARRAY_LEN(ary) - 1);
     }
     for (i=0; i<RARRAY_LEN(ary); i++) {
-	val = RARRAY_AREF(ary, i);
-	tmp = rb_check_string_type(val);
+        val = RARRAY_AREF(ary, i);
+        tmp = rb_check_string_type(val);
 
-	if (NIL_P(tmp) || tmp != val) {
-	    int first;
+        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());
+            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;
-	}
+            first = i == 0;
+            ary_join_1(ary, ary, sep, i, result, &first);
+            return result;
+        }
 
-	len += RSTRING_LEN(tmp);
+        len += RSTRING_LEN(tmp);
     }
 
     result = rb_str_new(0, len);
@@ -3052,41 +3049,27 @@ rb_ary_join(VALUE ary, VALUE sep)
  *    array.join(separator = $,) -> new_string
  *
  *  Returns the new \String formed by joining the array elements after conversion.
- *  For each element +element+
+ *  For each element +element+:
+ *
  *  - Uses <tt>element.to_s</tt> if +element+ is not a <tt>kind_of?(Array)</tt>.
  *  - Uses recursive <tt>element.join(separator)</tt> if +element+ is a <tt>kind_of?(Array)</tt>.
  *
- *  Argument +separator+, if given, must be a
- *  {String-convertible object}[doc/implicit_conversion_rdoc.html#label-String-Convertible+Objects].
- *
- *  ---
- *
  *  With no argument, joins using the output field separator, <tt>$,</tt>:
+ *
  *    a = [:foo, 'bar', 2]
  *    $, # => nil
  *    a.join # => "foobar2"
  *
- *  With argument +separator+, joins using that separator:
+ *  With \string argument +separator+, joins using that separator:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.join("\n") # => "foo\nbar\n2"
  *
- *  ---
- *
  *  Joins recursively for nested Arrays:
+ *
  *   a = [:foo, [:bar, [:baz, :bat]]]
  *   a.join # => "foobarbazbat"
  *
- *  ---
- *
- *  Raises an exception if +separator+ is not a String-convertible object:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into String):
- *    a.join(:foo)
- *
- *  Raises an exception if any element lacks instance method +#to_s+:
- *    a = [:foo, 'bar', 2, BasicObject.new]
- *    # Raises NoMethodError (undefined method `to_s' for #<BasicObject>):
- *    a.join
  */
 static VALUE
 rb_ary_join_m(int argc, VALUE *argv, VALUE ary)
@@ -3096,7 +3079,7 @@ rb_ary_join_m(int argc, VALUE *argv, VALUE ary)
     if (rb_check_arity(argc, 0, 1) == 0 || NIL_P(sep = argv[0])) {
         sep = rb_output_fs;
         if (!NIL_P(sep)) {
-            rb_warn("$, is set to non-nil value");
+            rb_category_warn(RB_WARN_CATEGORY_DEPRECATED, "$, is set to non-nil value");
         }
     }
 
@@ -3112,10 +3095,10 @@ inspect_ary(VALUE ary, VALUE dummy, int recur)
     if (recur) return rb_usascii_str_new_cstr("[...]");
     str = rb_str_buf_new2("[");
     for (i=0; i<RARRAY_LEN(ary); i++) {
-	s = rb_inspect(RARRAY_AREF(ary, i));
-	if (i > 0) rb_str_buf_cat2(str, ", ");
-	else rb_enc_copy(str, s);
-	rb_str_buf_append(str, s);
+        s = rb_inspect(RARRAY_AREF(ary, i));
+        if (i > 0) rb_str_buf_cat2(str, ", ");
+        else rb_enc_copy(str, s);
+        rb_str_buf_append(str, s);
     }
     rb_str_buf_cat2(str, "]");
     return str;
@@ -3124,19 +3107,14 @@ inspect_ary(VALUE ary, VALUE dummy, int recur)
 /*
  *  call-seq:
  *    array.inspect -> new_string
- *    array.to_s => new_string
- *
- *  Array#to_s is an alias for Array#inspect.
  *
  *  Returns the new \String formed by calling method <tt>#inspect</tt>
  *  on each array element:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.inspect # => "[:foo, \"bar\", 2]"
  *
- *  Raises an exception if any element lacks instance method <tt>#inspect</tt>:
- *    a = [:foo, 'bar', 2, BasicObject.new]
- *    a.inspect
- *    # Raises NoMethodError (undefined method `inspect' for #<BasicObject>)
+ *  Array#to_s is an alias for Array#inspect.
  */
 
 static VALUE
@@ -3157,12 +3135,12 @@ rb_ary_to_s(VALUE ary)
  *    to_a -> self or new_array
  *
  *  When +self+ is an instance of \Array, returns +self+:
+ *
  *    a = [:foo, 'bar', 2]
- *    a.instance_of?(Array) # => true
- *    a1 = a.to_a
- *    a1.equal?(a) # => true # Returned self
+ *    a.to_a # => [:foo, "bar", 2]
  *
  *  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
@@ -3170,15 +3148,16 @@ rb_ary_to_s(VALUE ary)
  *    a1 = a.to_a
  *    a1 # => ["foo", "bar", "two"]
  *    a1.class # => Array # Not MyArray
+ *
  */
 
 static VALUE
 rb_ary_to_a(VALUE ary)
 {
     if (rb_obj_class(ary) != rb_cArray) {
-	VALUE dup = rb_ary_new2(RARRAY_LEN(ary));
-	rb_ary_replace(dup, ary);
-	return dup;
+        VALUE dup = rb_ary_new2(RARRAY_LEN(ary));
+        rb_ary_replace(dup, ary);
+        return dup;
     }
     return ary;
 }
@@ -3193,30 +3172,19 @@ rb_ary_to_a(VALUE ary)
  *  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:
+ *
  *    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}}
  *
  *  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:
+ *
  *    [].to_h # => {}
  *    a = [['foo', 'zero'], ['bar', 'one'], ['baz', 'two']]
  *    h = a.to_h
  *    h # => {"foo"=>"zero", "bar"=>"one", "baz"=>"two"}
  *
- *  ---
- *
- *  Raises an exception if no block is given
- *  and any element in +self+ is not a 2-element \Array:
- *    # Raises TypeError (wrong element type Symbol at 0 (expected array):
- *    [:foo].to_h
- *    # Raises ArgumentError (wrong array length at 0 (expected 2, was 1)):
- *    [[:foo]].to_h
- *
- *  Raises an exception if for some 2-element \Array +element+ in +self+,
- *  <tt>element.first</tt> would be an invalid hash key:
- *    # Raises NoMethodError (undefined method `hash' for #<BasicObject:>):
- *    [[BasicObject.new, 0]].to_h
  */
 
 static VALUE
@@ -3227,18 +3195,18 @@ rb_ary_to_h(VALUE ary)
     int block_given = rb_block_given_p();
 
     for (i=0; i<RARRAY_LEN(ary); i++) {
-	const VALUE e = rb_ary_elt(ary, i);
-	const VALUE elt = block_given ? rb_yield_force_blockarg(e) : e;
-	const VALUE key_value_pair = rb_check_array_type(elt);
-	if (NIL_P(key_value_pair)) {
-	    rb_raise(rb_eTypeError, "wrong element type %"PRIsVALUE" at %ld (expected array)",
-		     rb_obj_class(elt), i);
-	}
-	if (RARRAY_LEN(key_value_pair) != 2) {
-	    rb_raise(rb_eArgError, "wrong array length at %ld (expected 2, was %ld)",
-		i, RARRAY_LEN(key_value_pair));
-	}
-	rb_hash_aset(hash, RARRAY_AREF(key_value_pair, 0), RARRAY_AREF(key_value_pair, 1));
+        const VALUE e = rb_ary_elt(ary, i);
+        const VALUE elt = block_given ? rb_yield_force_blockarg(e) : e;
+        const VALUE key_value_pair = rb_check_array_type(elt);
+        if (NIL_P(key_value_pair)) {
+            rb_raise(rb_eTypeError, "wrong element type %"PRIsVALUE" at %ld (expected array)",
+                     rb_obj_class(elt), i);
+        }
+        if (RARRAY_LEN(key_value_pair) != 2) {
+            rb_raise(rb_eArgError, "wrong array length at %ld (expected 2, was %ld)",
+                i, RARRAY_LEN(key_value_pair));
+        }
+        rb_hash_aset(hash, RARRAY_AREF(key_value_pair, 0), RARRAY_AREF(key_value_pair, 1));
     }
     return hash;
 }
@@ -3247,10 +3215,7 @@ rb_ary_to_h(VALUE ary)
  *  call-seq:
  *    array.to_ary -> self
  *
- *  Returns +self+:
- *    a = [:foo, 'bar', 2]
- *    a1 = a.to_ary
- *    a1.equal?(a) # => true # Returned self
+ *  Returns +self+.
  */
 
 static VALUE
@@ -3263,9 +3228,9 @@ static void
 ary_reverse(VALUE *p1, VALUE *p2)
 {
     while (p1 < p2) {
-	VALUE tmp = *p1;
-	*p1++ = *p2;
-	*p2-- = tmp;
+        VALUE tmp = *p1;
+        *p1++ = *p2;
+        *p2-- = tmp;
     }
 }
 
@@ -3280,7 +3245,7 @@ rb_ary_reverse(VALUE ary)
         RARRAY_PTR_USE_TRANSIENT(ary, p1, {
             p2 = p1 + len - 1;	/* points last item */
             ary_reverse(p1, p2);
-	}); /* WB: no new reference */
+        }); /* WB: no new reference */
     }
     return ary;
 }
@@ -3290,10 +3255,10 @@ rb_ary_reverse(VALUE ary)
  *    array.reverse! -> self
  *
  *  Reverses +self+ in place:
+ *
  *    a = ['foo', 'bar', 'two']
- *    a1 = a.reverse!
- *    a1 # => ["two", "bar", "foo"]
- *    a1.equal?(a) # => true # Returned self
+ *    a.reverse! # => ["two", "bar", "foo"]
+ *
  */
 
 static VALUE
@@ -3306,10 +3271,12 @@ rb_ary_reverse_bang(VALUE ary)
  *  call-seq:
  *    array.reverse -> new_array
  *
- *  Returns a new \Array whose elements are in reverse order:
+ *  Returns a new \Array with the elements of +self+ in reverse order:
+ *
  *    a = ['foo', 'bar', 'two']
  *    a1 = a.reverse
  *    a1 # => ["two", "bar", "foo"]
+ *
  */
 
 static VALUE
@@ -3321,7 +3288,7 @@ rb_ary_reverse_m(VALUE ary)
     if (len > 0) {
         const VALUE *p1 = RARRAY_CONST_PTR_TRANSIENT(ary);
         VALUE *p2 = (VALUE *)RARRAY_CONST_PTR_TRANSIENT(dup) + len - 1;
-	do *p2-- = *p1++; while (--len > 0);
+        do *p2-- = *p1++; while (--len > 0);
     }
     ARY_SET_LEN(dup, RARRAY_LEN(ary));
     return dup;
@@ -3340,11 +3307,13 @@ ary_rotate_ptr(VALUE *ptr, long len, long cnt)
         VALUE tmp = *ptr;
         memmove(ptr, ptr + 1, sizeof(VALUE)*(len - 1));
         *(ptr + len - 1) = tmp;
-    } else if (cnt == len - 1) {
+    }
+    else if (cnt == len - 1) {
         VALUE tmp = *(ptr + len - 1);
         memmove(ptr + 1, ptr, sizeof(VALUE)*(len - 1));
         *ptr = tmp;
-    } else {
+    }
+    else {
         --len;
         if (cnt < len) ary_reverse(ptr + cnt, ptr + len);
         if (--cnt > 0) ary_reverse(ptr, ptr + cnt);
@@ -3374,53 +3343,43 @@ rb_ary_rotate(VALUE ary, long cnt)
  *
  *  Rotates +self+ in place by moving elements from one end to the other; returns +self+.
  *
- *  Argument +count+, if given, must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *
- *  ---
- *
  *  When no argument given, rotates the first element to the last position:
+ *
  *    a = [:foo, 'bar', 2, 'bar']
- *    a1 = a.rotate!
- *    a1 # => ["bar", 2, "bar", :foo]
- *    a1.equal?(a1) # => true # Retruned self
+ *    a.rotate! # => ["bar", 2, "bar", :foo]
  *
- *  ---
+ *  When given a non-negative \Integer +count+,
+ *  rotates +count+ elements from the beginning to the end:
  *
- *  When given a non-negative +count+, rotates +count+ elements from the beginning to the end:
  *    a = [:foo, 'bar', 2]
  *    a.rotate!(2)
  *    a # => [2, :foo, "bar"]
  *
- *  If +count+ is large, uses <tt>count % ary.size</tt> as the count:
+ *  If +count+ is large, uses <tt>count % array.size</tt> as the count:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.rotate!(20)
  *    a # => [2, :foo, "bar"]
  *
  *  If +count+ is zero, returns +self+ unmodified:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.rotate!(0)
  *    a # => [:foo, "bar", 2]
  *
- *  ---
- *
- *  When given a negative +count+, rotates in the opposite direction,
+ *  When given a negative Integer +count+, rotates in the opposite direction,
  *  from end to beginning:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.rotate!(-2)
  *    a # => ["bar", 2, :foo]
  *
- *  If +count+ is small (far from zero), uses <tt>count % ary.size</tt> as the count:
+ *  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]
  *
- *  ---
- *
- *  Raises an exception if +count+ is not an Integer-convertible object:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a1 = a.rotate!(:foo)
  */
 
 static VALUE
@@ -3439,53 +3398,45 @@ rb_ary_rotate_bang(int argc, VALUE *argv, VALUE ary)
  *  Returns a new \Array formed from +self+ with elements
  *  rotated from one end to the other.
  *
- *  Argument +count+, if given, must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *
- *  ---
  *  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]
  *
- *  ---
- *
- *  When given a non-negative +count+,
+ *  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"]
  *
- *  If +count+ is large, uses <tt>count % ary.size</tt> as the count:
+ *  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"]
  *
  *  If +count+ is zero, returns a copy of +self+, unmodified:
+ *
  *    a = [:foo, 'bar', 2]
  *    a1 = a.rotate(0)
  *    a1 # => [:foo, "bar", 2]
  *
- *  ---
- *
- *  When given a negative +count+, rotates in the opposite direction,
+ *  When given a negative \Integer +count+, rotates in the opposite direction,
  *  from end to beginning:
+ *
  *    a = [:foo, 'bar', 2]
  *    a1 = a.rotate(-2)
  *    a1 # => ["bar", 2, :foo]
  *
- *  If +count+ is small (far from zero), uses <tt>count % ary.size</tt> as the count:
+ *  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]
  *
- *  ---
- *
- *  Raises an exception if +count+ is not an Integer-convertible object:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a1 = a.rotate(:foo)
  */
 
 static VALUE
@@ -3499,11 +3450,11 @@ rb_ary_rotate_m(int argc, VALUE *argv, VALUE ary)
     len = RARRAY_LEN(ary);
     rotated = rb_ary_new2(len);
     if (len > 0) {
-	cnt = rotate_count(cnt, len);
+        cnt = rotate_count(cnt, len);
         ptr = RARRAY_CONST_PTR_TRANSIENT(ary);
-	len -= cnt;
-	ary_memcpy(rotated, 0, len, ptr + cnt);
-	ary_memcpy(rotated, len, cnt, ptr);
+        len -= cnt;
+        ary_memcpy(rotated, 0, len, ptr + cnt);
+        ary_memcpy(rotated, len, cnt, ptr);
     }
     ARY_SET_LEN(rotated, RARRAY_LEN(ary));
     return rotated;
@@ -3511,18 +3462,27 @@ rb_ary_rotate_m(int argc, VALUE *argv, VALUE ary)
 
 struct ary_sort_data {
     VALUE ary;
-    struct cmp_opt_data cmp_opt;
+    VALUE receiver;
 };
 
 static VALUE
 sort_reentered(VALUE ary)
 {
     if (RBASIC(ary)->klass) {
-	rb_raise(rb_eRuntimeError, "sort reentered");
+        rb_raise(rb_eRuntimeError, "sort reentered");
     }
     return Qnil;
 }
 
+static void
+sort_returned(struct ary_sort_data *data)
+{
+    if (rb_obj_frozen_p(data->receiver)) {
+        rb_raise(rb_eFrozenError, "array frozen during sort");
+    }
+    sort_reentered(data->ary);
+}
+
 static int
 sort_1(const void *ap, const void *bp, void *dummy)
 {
@@ -3536,7 +3496,7 @@ sort_1(const void *ap, const void *bp, void *dummy)
     args[1] = b;
     retval = rb_yield_values2(2, args);
     n = rb_cmpint(retval, a, b);
-    sort_reentered(data->ary);
+    sort_returned(data);
     return n;
 }
 
@@ -3548,21 +3508,21 @@ 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 ((long)a > (long)b) return 1;
-	if ((long)a < (long)b) return -1;
-	return 0;
+    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)) {
-	return rb_str_cmp(a, b);
+    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)) {
-	return rb_float_cmp(a, b);
+    if (RB_FLOAT_TYPE_P(a) && CMP_OPTIMIZABLE(FLOAT)) {
+        return rb_float_cmp(a, b);
     }
 
     retval = rb_funcallv(a, id_cmp, 1, &b);
     n = rb_cmpint(retval, a, b);
-    sort_reentered(data->ary);
+    sort_returned(data);
 
     return n;
 }
@@ -3574,24 +3534,23 @@ sort_2(const void *ap, const void *bp, void *dummy)
  *
  *  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 }
@@ -3601,17 +3560,12 @@ sort_2(const void *ap, const void *bp, void *dummy)
  *
  *  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"]
  *
- *  ---
- *
- *  Raises an exception if the block returns a non-Integer:
- *    a = 'abcde'.split('').shuffle
- *    # Raises ArgumentError (comparison of Symbol with 0 failed):
- *    a1 = a.sort! {|a, b| :foo }
  */
 
 VALUE
@@ -3620,24 +3574,23 @@ rb_ary_sort_bang(VALUE ary)
     rb_ary_modify(ary);
     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;
-	long len = RARRAY_LEN(ary);
-	RBASIC_CLEAR_CLASS(tmp);
-	data.ary = tmp;
-	data.cmp_opt.opt_methods = 0;
-	data.cmp_opt.opt_inited = 0;
-	RARRAY_PTR_USE(tmp, ptr, {
+        VALUE tmp = ary_make_substitution(ary); /* only ary refers tmp */
+        struct ary_sort_data data;
+        long len = RARRAY_LEN(ary);
+        RBASIC_CLEAR_CLASS(tmp);
+        data.ary = tmp;
+        data.receiver = ary;
+        RARRAY_PTR_USE(tmp, ptr, {
             ruby_qsort(ptr, len, sizeof(VALUE),
                        rb_block_given_p()?sort_1:sort_2, &data);
-	}); /* WB: no new reference */
-	rb_ary_modify(ary);
+        }); /* WB: no new reference */
+        rb_ary_modify(ary);
         if (ARY_EMBED_P(tmp)) {
             if (ARY_SHARED_P(ary)) { /* ary might be destructively operated in the given block */
                 rb_ary_unshare(ary);
-		FL_SET_EMBED(ary);
+                FL_SET_EMBED(ary);
             }
-	    ary_memcpy(ary, 0, ARY_EMBED_LEN(tmp), ARY_EMBED_PTR(tmp));
+            ary_memcpy(ary, 0, ARY_EMBED_LEN(tmp), ARY_EMBED_PTR(tmp));
             ARY_SET_LEN(ary, ARY_EMBED_LEN(tmp));
         }
         else {
@@ -3681,26 +3634,23 @@ rb_ary_sort_bang(VALUE ary)
  *
  *  Returns a new \Array whose elements are those from +self+, sorted.
  *
- *  See also Enumerable#sort_by.
- *
- *  ---
- *
  *  With no block, compares elements using operator <tt><=></tt>
  *  (see Comparable):
+ *
  *    a = 'abcde'.split('').shuffle
  *    a # => ["e", "b", "d", "a", "c"]
  *    a1 = a.sort
  *    a1 # => ["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"]
  *    a1 = a.sort {|a, b| a <=> b }
@@ -3710,17 +3660,13 @@ rb_ary_sort_bang(VALUE ary)
  *
  *  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"]
  *    a1 = a.sort {|a, b| 0 }
  *    a1 # =>  ["c", "e", "b", "d", "a"]
  *
- *  ---
- *
- *  Raises an exception if the block returns a non-Integer:
- *    a = 'abcde'.split('').shuffle
- *    # Raises ArgumentError (comparison of Symbol with 0 failed):
- *    a1 = a.sort {|a, b| :foo }
+ *  Related: Enumerable#sort_by.
  */
 
 VALUE
@@ -3739,98 +3685,8 @@ static VALUE rb_ary_bsearch_index(VALUE ary);
  *    array.bsearch -> new_enumerator
  *
  *  Returns an element from +self+ selected by a binary search.
- *  +self+ should be sorted, but this is not checked.
- *
- *  By using binary search, finds a value from this array which meets
- *  the given condition in <tt>O(log n)</tt> where +n+ is the size of the array.
- *
- *  There are two search modes:
- *  - <b>Find-minimum mode</b>: the block should return +true+ or +false+.
- *  - <b>Find-any mode</b>: the block should return a numeric value.
- *
- *  The block should not mix the modes by and sometimes returning +true+ or +false+
- *  and sometimes returning a numeric value, but this is not checked.
- *
- *  ====== Find-Minimum Mode
- *
- *  In find-minimum mode, the block always returns +true+ or +false+.
- *  The further requirement (though not checked) is that
- *  there are no indexes +i+ and +j+ such that:
- *  - <tt>0 <= i < j <= self.size</tt>.
- *  - The block returns +true+ for <tt>self[i]</tt> and +false+ for <tt>self[j]</tt>.
- *
- *  In find-minimum mode, method bsearch returns the first element for which the block returns true.
- *
- *  Examples:
- *    a = [0, 4, 7, 10, 12]
- *    a.bsearch {|x| x >= 4 } # => 4
- *    a.bsearch {|x| x >= 6 } # => 7
- *    a.bsearch {|x| x >= -1 } # => 0
- *    a.bsearch {|x| x >= 100 } # => nil
- *
- *  Less formally: the block is such that all +false+-evaluating elements
- *  precede all +true+-evaluating elements.
- *
- *  These make sense as blocks in find-minimum mode:
- *    a = [0, 4, 7, 10, 12]
- *    a.map {|x| x >= 4 } # => [false, true, true, true, true]
- *    a.map {|x| x >= 6 } # => [false, false, true, true, true]
- *    a.map {|x| x >= -1 } # => [true, true, true, true, true]
- *    a.map {|x| x >= 100 } # => [false, false, false, false, false]
- *
- *  This would not make sense:
- *    a = [0, 4, 7, 10, 12]
- *    a.map {|x| x == 7 } # => [false, false, true, false, false]
- *
- *  ====== Find-Any Mode
- *
- *  In find-any mode, the block always returns a numeric value.
- *  The further requirement (though not checked) is that
- *  there are no indexes +i+ and +j+ such that:
- *  - <tt>0 <= i < j <= self.size</tt>.
- *  - The block returns a negative value for <tt>self[i]</tt>
- *    and a positive value for <tt>self[j]</tt>.
- *  - The block returns a negative value for <tt>self[i]</tt> and zero <tt>self[j]</tt>.
- *  - The block returns zero for <tt>self[i]</tt> and a positive value for <tt>self[j]</tt>.
- *
- *  In find-any mode, method bsearch returns some element
- *  for which the block returns zero, or +nil+ if no such element is found.
- *
- *  Examples:
- *    a = [0, 4, 7, 10, 12]
- *    a.bsearch {|element| 7 <=> element } # => 7
- *    a.bsearch {|element| -1 <=> element } # => nil
- *    a.bsearch {|element| 5 <=> element } # => nil
- *    a.bsearch {|element| 15 <=> element } # => nil
- *
- *  Less formally: the block is such that:
- *  - All positive-evaluating elements precede all zero-evaluating elements.
- *  - All positive-evaluating elements precede all negative-evaluating elements.
- *  - All zero-evaluating elements precede all negative-evaluating elements.
- *
- *  These make sense as blocks in find-any mode:
- *    a = [0, 4, 7, 10, 12]
- *    a.map {|element| 7 <=> element } # => [1, 1, 0, -1, -1]
- *    a.map {|element| -1 <=> element } # => [-1, -1, -1, -1, -1]
- *    a.map {|element| 5 <=> element } # => [1, 1, -1, -1, -1]
- *    a.map {|element| 15 <=> element } # => [1, 1, 1, 1, 1]
  *
- *  This would not make sense:
- *    a = [0, 4, 7, 10, 12]
- *    a.map {|element| element <=> 7 } # => [-1, -1, 0, 1, 1]
- *
- *  ---
- *
- *  Returns an enumerator if no block given:
- *    a = [0, 4, 7, 10, 12]
- *    a.bsearch # => #<Enumerator: [0, 4, 7, 10, 12]:bsearch>
- *
- *  ---
- *
- *  Raises an exception if the block returns an invalid value:
- *    a = 'abcde'.split('').shuffle
- *    # Raises TypeError (wrong argument type Symbol (must be numeric, true, false or nil)):
- *    a.bsearch {|element| :foo }
+ *  See {Binary Searching}[rdoc-ref:bsearch.rdoc].
  */
 
 static VALUE
@@ -3839,7 +3695,7 @@ rb_ary_bsearch(VALUE ary)
     VALUE index_result = rb_ary_bsearch_index(ary);
 
     if (FIXNUM_P(index_result)) {
-	return rb_ary_entry(ary, FIX2LONG(index_result));
+        return rb_ary_entry(ary, FIX2LONG(index_result));
     }
     return index_result;
 }
@@ -3862,39 +3718,39 @@ rb_ary_bsearch_index(VALUE ary)
 
     RETURN_ENUMERATOR(ary, 0, 0);
     while (low < high) {
-	mid = low + ((high - low) / 2);
-	val = rb_ary_entry(ary, mid);
-	v = rb_yield(val);
-	if (FIXNUM_P(v)) {
-	    if (v == INT2FIX(0)) return INT2FIX(mid);
-	    smaller = (SIGNED_VALUE)v < 0; /* Fixnum preserves its sign-bit */
-	}
-	else if (v == Qtrue) {
-	    satisfied = 1;
-	    smaller = 1;
-	}
-	else if (v == Qfalse || v == Qnil) {
-	    smaller = 0;
-	}
-	else if (rb_obj_is_kind_of(v, rb_cNumeric)) {
-	    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;
-	    }
-	}
-	else {
-	    rb_raise(rb_eTypeError, "wrong argument type %"PRIsVALUE
-		     " (must be numeric, true, false or nil)",
-		     rb_obj_class(v));
-	}
-	if (smaller) {
-	    high = mid;
-	}
-	else {
-	    low = mid + 1;
-	}
+        mid = low + ((high - low) / 2);
+        val = rb_ary_entry(ary, mid);
+        v = rb_yield(val);
+        if (FIXNUM_P(v)) {
+            if (v == INT2FIX(0)) return INT2FIX(mid);
+            smaller = (SIGNED_VALUE)v < 0; /* Fixnum preserves its sign-bit */
+        }
+        else if (v == Qtrue) {
+            satisfied = 1;
+            smaller = 1;
+        }
+        else if (!RTEST(v)) {
+            smaller = 0;
+        }
+        else if (rb_obj_is_kind_of(v, rb_cNumeric)) {
+            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 = 0; break;
+              case -1: smaller = 1;
+            }
+        }
+        else {
+            rb_raise(rb_eTypeError, "wrong argument type %"PRIsVALUE
+                     " (must be numeric, true, false or nil)",
+                     rb_obj_class(v));
+        }
+        if (smaller) {
+            high = mid;
+        }
+        else {
+            low = mid + 1;
+        }
     }
     if (!satisfied) return Qnil;
     return INT2FIX(low);
@@ -3921,16 +3777,16 @@ sort_by_i(RB_BLOCK_CALL_FUNC_ARGLIST(i, dummy))
  *  For duplicates returned by the block, the ordering is indeterminate, and may be unstable.
  *
  *  This example sorts strings based on their sizes:
+ *
  *    a = ['aaaa', 'bbb', 'cc', 'd']
  *    a.sort_by! {|element| element.size }
  *    a # => ["d", "cc", "bbb", "aaaa"]
  *
- *  ---
- *
  *  Returns a new \Enumerator if no block given:
  *
  *    a = ['aaaa', 'bbb', 'cc', 'd']
  *    a.sort_by! # => #<Enumerator: ["aaaa", "bbb", "cc", "d"]:sort_by!>
+ *
  */
 
 static VALUE
@@ -3950,23 +3806,20 @@ rb_ary_sort_by_bang(VALUE ary)
  *  call-seq:
  *    array.map {|element| ... } -> new_array
  *    array.map -> new_enumerator
- *    array.collect {|element| ... } -> new_array
- *    array.collect -> new_enumerator
- *
- *  Array#map is an alias for Array#collect.
  *
  *  Calls the block, if given, with each element of +self+;
  *  returns a new \Array whose elements are the return values from the block:
+ *
  *    a = [:foo, 'bar', 2]
- *    a1 = a.collect {|element| element.class }
+ *    a1 = a.map {|element| element.class }
  *    a1 # => [Symbol, String, Integer]
  *
- *  ---
- *
  *  Returns a new \Enumerator if no block given:
  *    a = [:foo, 'bar', 2]
- *    a1 = a.collect
- *    a1 # => #<Enumerator: [:foo, "bar", 2]:collect>
+ *    a1 = a.map
+ *    a1 # => #<Enumerator: [:foo, "bar", 2]:map>
+ *
+ *  Array#collect is an alias for Array#map.
  */
 
 static VALUE
@@ -3988,24 +3841,20 @@ rb_ary_collect(VALUE ary)
  *  call-seq:
  *    array.map! {|element| ... } -> self
  *    array.map! -> new_enumerator
- *    array.collect! {|element| ... } -> self
- *    array.collect! -> new_enumerator
- *
- *  Array#map! is an alias for Array#collect!.
  *
  *  Calls the block, if given, with each element;
  *  replaces the element with the block's return value:
- *    a = [:foo, 'bar', 2]
- *    a1 = a.collect! { |element| element.class }
- *    a1 # => [Symbol, String, Integer]
- *    a1.equal?(a) # => true # Returned self
  *
- *  ---
+ *    a = [:foo, 'bar', 2]
+ *    a.map! { |element| element.class } # => [Symbol, String, Integer]
  *
  *  Returns a new \Enumerator if no block given:
+ *
  *    a = [:foo, 'bar', 2]
- *    a1 = a.collect!
- *    a1 # => #<Enumerator: [:foo, "bar", 2]:collect!>
+ *    a1 = a.map!
+ *    a1 # => #<Enumerator: [:foo, "bar", 2]:map!>
+ *
+ *  Array#collect! is an alias for Array#map!.
  */
 
 static VALUE
@@ -4016,7 +3865,7 @@ rb_ary_collect_bang(VALUE ary)
     RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
     rb_ary_modify(ary);
     for (i = 0; i < RARRAY_LEN(ary); i++) {
-	rb_ary_store(ary, i, rb_yield(RARRAY_AREF(ary, i)));
+        rb_ary_store(ary, i, rb_yield(RARRAY_AREF(ary, i)));
     }
     return ary;
 }
@@ -4028,21 +3877,21 @@ rb_get_values_at(VALUE obj, long olen, int argc, const VALUE *argv, VALUE (*func
     long beg, len, i, j;
 
     for (i=0; i<argc; i++) {
-	if (FIXNUM_P(argv[i])) {
-	    rb_ary_push(result, (*func)(obj, FIX2LONG(argv[i])));
-	    continue;
-	}
-	/* check if idx is Range */
-	if (rb_range_beg_len(argv[i], &beg, &len, olen, 1)) {
-	    long end = olen < beg+len ? olen : beg+len;
-	    for (j = beg; j < end; j++) {
-		rb_ary_push(result, (*func)(obj, j));
-	    }
-	    if (beg + len > j)
-		rb_ary_resize(result, RARRAY_LEN(result) + (beg + len) - j);
-	    continue;
-	}
-	rb_ary_push(result, (*func)(obj, NUM2LONG(argv[i])));
+        if (FIXNUM_P(argv[i])) {
+            rb_ary_push(result, (*func)(obj, FIX2LONG(argv[i])));
+            continue;
+        }
+        /* check if idx is Range */
+        if (rb_range_beg_len(argv[i], &beg, &len, olen, 1)) {
+            long end = olen < beg+len ? olen : beg+len;
+            for (j = beg; j < end; j++) {
+                rb_ary_push(result, (*func)(obj, j));
+            }
+            if (beg + len > j)
+                rb_ary_resize(result, RARRAY_LEN(result) + (beg + len) - j);
+            continue;
+        }
+        rb_ary_push(result, (*func)(obj, NUM2LONG(argv[i])));
     }
     return result;
 }
@@ -4052,25 +3901,25 @@ append_values_at_single(VALUE result, VALUE ary, long olen, VALUE idx)
 {
     long beg, len;
     if (FIXNUM_P(idx)) {
-	beg = FIX2LONG(idx);
+        beg = FIX2LONG(idx);
     }
     /* check if idx is Range */
     else if (rb_range_beg_len(idx, &beg, &len, olen, 1)) {
-	if (len > 0) {
+        if (len > 0) {
             const VALUE *const src = RARRAY_CONST_PTR_TRANSIENT(ary);
-	    const long end = beg + len;
-	    const long prevlen = RARRAY_LEN(result);
-	    if (beg < olen) {
-		rb_ary_cat(result, src + beg, end > olen ? olen-beg : len);
-	    }
-	    if (end > olen) {
-		rb_ary_store(result, prevlen + len - 1, Qnil);
-	    }
-	}
-	return result;
+            const long end = beg + len;
+            const long prevlen = RARRAY_LEN(result);
+            if (beg < olen) {
+                rb_ary_cat(result, src + beg, end > olen ? olen-beg : len);
+            }
+            if (end > olen) {
+                rb_ary_store(result, prevlen + len - 1, Qnil);
+            }
+        }
+        return result;
     }
     else {
-	beg = NUM2LONG(idx);
+        beg = NUM2LONG(idx);
     }
     return rb_ary_push(result, rb_ary_entry(ary, beg));
 }
@@ -4080,48 +3929,42 @@ append_values_at_single(VALUE result, VALUE ary, long olen, VALUE idx)
  *    array.values_at(*indexes) -> new_array
  *
  *  Returns a new \Array whose elements are the elements
- *  of +self+ at the given +indexes+.
- *
- *  Each +index+ given in +indexes+ must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *
- *  ---
+ *  of +self+ at the given \Integer or \Range +indexes+.
  *
  *  For each positive +index+, returns the element at offset +index+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.values_at(0, 2) # => [:foo, 2]
+ *    a.values_at(0..1) # => [:foo, "bar"]
  *
  *  The given +indexes+ may be in any order, and may repeat:
+ *
  *    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]
  *
  *  Assigns +nil+ for an +index+ that is too large:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.values_at(0, 3, 1, 3) # => [:foo, nil, "bar", nil]
  *
- *  Returns a new empty \Array if no arguments given:
- *    [].values_at # => []
- *
- *  ---
+ *  Returns a new empty \Array if no arguments given.
  *
  *  For each negative +index+, counts backward from the end of the array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.values_at(-1, -3) # => [2, :foo]
  *
  *  Assigns +nil+ for an +index+ that is too small:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.values_at(0, -5, 1, -6, 2) # => [:foo, nil, "bar", nil, 2]
  *
  *  The given +indexes+ may have a mixture of signs:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.values_at(0, -2, 1, -1) # => [:foo, "bar", "bar", 2]
  *
- *  ---
- *
- *  Raises an exception if any +index+ is not an Integer-convertible object:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.values_at(0, :foo)
  */
 
 static VALUE
@@ -4130,7 +3973,7 @@ rb_ary_values_at(int argc, VALUE *argv, VALUE ary)
     long i, olen = RARRAY_LEN(ary);
     VALUE result = rb_ary_new_capa(argc);
     for (i = 0; i < argc; ++i) {
-	append_values_at_single(result, ary, olen, argv[i]);
+        append_values_at_single(result, ary, olen, argv[i]);
     }
     RB_GC_GUARD(ary);
     return result;
@@ -4141,23 +3984,21 @@ rb_ary_values_at(int argc, VALUE *argv, VALUE ary)
  *  call-seq:
  *    array.select {|element| ... } -> new_array
  *    array.select -> new_enumerator
- *    array.filter {|element| ... } -> new_array
- *    array.filter -> new_enumerator
- *
- *  Array#filter is an alias for Array#select.
  *
  *  Calls the block, if given, 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 = [:foo, 'bar', 2, :bam]
  *    a.select # => #<Enumerator: [:foo, "bar", 2, :bam]:select>
+ *
+ *  Array#filter is an alias for Array#select.
  */
 
 static VALUE
@@ -4169,9 +4010,9 @@ rb_ary_select(VALUE ary)
     RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
     result = rb_ary_new2(RARRAY_LEN(ary));
     for (i = 0; i < RARRAY_LEN(ary); i++) {
-	if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) {
-	    rb_ary_push(result, rb_ary_elt(ary, i));
-	}
+        if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) {
+            rb_ary_push(result, rb_ary_elt(ary, i));
+        }
     }
     return result;
 }
@@ -4189,12 +4030,12 @@ select_bang_i(VALUE a)
     long i1, i2;
 
     for (i1 = i2 = 0; i1 < RARRAY_LEN(ary); arg->len[0] = ++i1) {
-	VALUE v = RARRAY_AREF(ary, i1);
-	if (!RTEST(rb_yield(v))) continue;
-	if (i1 != i2) {
-	    rb_ary_store(ary, i2, v);
-	}
-	arg->len[1] = ++i2;
+        VALUE v = RARRAY_AREF(ary, i1);
+        if (!RTEST(rb_yield(v))) continue;
+        if (i1 != i2) {
+            rb_ary_store(ary, i2, v);
+        }
+        arg->len[1] = ++i2;
     }
     return (i1 == i2) ? Qnil : ary;
 }
@@ -4208,14 +4049,15 @@ select_bang_ensure(VALUE a)
     long i1 = arg->len[0], i2 = arg->len[1];
 
     if (i2 < len && i2 < i1) {
-	long tail = 0;
-	if (i1 < len) {
-	    tail = len - i1;
+        long tail = 0;
+        rb_ary_modify(ary);
+        if (i1 < len) {
+            tail = len - i1;
             RARRAY_PTR_USE_TRANSIENT(ary, ptr, {
-		    MEMMOVE(ptr + i2, ptr + i1, VALUE, tail);
-		});
-	}
-	ARY_SET_LEN(ary, i2 + tail);
+                    MEMMOVE(ptr + i2, ptr + i1, VALUE, tail);
+                });
+        }
+        ARY_SET_LEN(ary, i2 + tail);
     }
     return ary;
 }
@@ -4224,29 +4066,23 @@ select_bang_ensure(VALUE a)
  *  call-seq:
  *    array.select! {|element| ... } -> self or nil
  *    array.select! -> new_enumerator
- *    array.filter! {|element| ... } -> self or nil
- *    array.filter! -> new_enumerator
- *
- *  Array#filter! is an alias for Array#select!.
  *
  *  Calls the block, if given  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:
- *    a = [:foo, 'bar', 2, :bam]
- *    a1 = a.select! {|element| element.to_s.start_with?('b') }
- *    a1 # => ["bar", :bam]
- *    a1.equal?(a) # => true # Returned self
  *
- *  Returns +nil+ if no elements were removed:
  *    a = [:foo, 'bar', 2, :bam]
- *    a.select! { |element| element.kind_of?(Object) } # => nil
+ *    a.select! {|element| element.to_s.start_with?('b') } # => ["bar", :bam]
  *
- *  ---
+ *  Returns +nil+ if no elements were removed.
  *
  *  Returns a new \Enumerator if no block given:
+ *
  *    a = [:foo, 'bar', 2, :bam]
  *    a.select! # => #<Enumerator: [:foo, "bar", 2, :bam]:select!>
+ *
+ *  Array#filter! is an alias for Array#select!.
  */
 
 static VALUE
@@ -4269,14 +4105,15 @@ rb_ary_select_bang(VALUE ary)
  *
  *  Retains those elements for which the block returns a truthy value;
  *  deletes all other elements; returns +self+:
+ *
  *    a = [:foo, 'bar', 2, :bam]
- *    a1 = a.keep_if {|element| element.to_s.start_with?('b') }
- *    a1 # => ["bar", :bam]
- *    a1.equal?(a) # => true # Returned self
+ *    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>
+ *
  */
 
 static VALUE
@@ -4292,11 +4129,11 @@ ary_resize_smaller(VALUE ary, long len)
 {
     rb_ary_modify(ary);
     if (RARRAY_LEN(ary) > len) {
-	ARY_SET_LEN(ary, len);
-	if (len * 2 < ARY_CAPA(ary) &&
-	    ARY_CAPA(ary) > ARY_DEFAULT_SIZE) {
-	    ary_resize_capa(ary, len * 2);
-	}
+        ARY_SET_LEN(ary, len);
+        if (len * 2 < ARY_CAPA(ary) &&
+            ARY_CAPA(ary) > ARY_DEFAULT_SIZE) {
+            ary_resize_capa(ary, len * 2);
+        }
     }
 }
 
@@ -4305,39 +4142,35 @@ ary_resize_smaller(VALUE ary, long len)
  *    array.delete(obj) -> deleted_object
  *    array.delete(obj) {|nosuch| ... } -> deleted_object or block_return
  *
- *  Removes zero or more elements from +self+; returns +self+.
- *
- *  ---
+ *  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:
+ *
  *    s1 = 'bar'; s2 = 'bar'
  *    a = [:foo, s1, 2, s2]
- *    deleted_obj = a.delete('bar')
+ *    a.delete('bar') # => "bar"
  *    a # => [:foo, 2]
- *    deleted_obj.equal?(s2) # => true # Returned self
  *
- *  Returns +nil+ if no elements removed:
- *    a = [:foo, 'bar', 2]
- *    a.delete(:nosuch) # => nil
- *
- *  ---
+ *  Returns +nil+ if no elements removed.
  *
  *  When a block is given,
  *  removes from +self+ each element +ele+ such that <tt>ele == obj</tt>.
  *
  *  If any such elements are found, ignores the block
  *  and returns the last deleted element:
+ *
  *    s1 = 'bar'; s2 = 'bar'
  *    a = [:foo, s1, 2, s2]
  *    deleted_obj = a.delete('bar') {|obj| fail 'Cannot happen' }
  *    a # => [:foo, 2]
- *    deleted_obj.object_id == s2.object_id # => true
  *
  *  If no such elements are found, returns the block's return value:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.delete(:nosuch) {|obj| "#{obj} not found" } # => "nosuch not found"
+ *
  */
 
 VALUE
@@ -4347,22 +4180,22 @@ rb_ary_delete(VALUE ary, VALUE item)
     long i1, i2;
 
     for (i1 = i2 = 0; i1 < RARRAY_LEN(ary); i1++) {
-	VALUE e = RARRAY_AREF(ary, i1);
+        VALUE e = RARRAY_AREF(ary, i1);
 
-	if (rb_equal(e, item)) {
-	    v = e;
-	    continue;
-	}
-	if (i1 != i2) {
-	    rb_ary_store(ary, i2, e);
-	}
-	i2++;
+        if (rb_equal(e, item)) {
+            v = e;
+            continue;
+        }
+        if (i1 != i2) {
+            rb_ary_store(ary, i2, e);
+        }
+        i2++;
     }
     if (RARRAY_LEN(ary) == i2) {
-	if (rb_block_given_p()) {
-	    return rb_yield(item);
-	}
-	return Qnil;
+        if (rb_block_given_p()) {
+            return rb_yield(item);
+        }
+        return Qnil;
     }
 
     ary_resize_smaller(ary, i2);
@@ -4377,18 +4210,18 @@ rb_ary_delete_same(VALUE ary, VALUE item)
     long i1, i2;
 
     for (i1 = i2 = 0; i1 < RARRAY_LEN(ary); i1++) {
-	VALUE e = RARRAY_AREF(ary, i1);
+        VALUE e = RARRAY_AREF(ary, i1);
 
-	if (e == item) {
-	    continue;
-	}
-	if (i1 != i2) {
-	    rb_ary_store(ary, i2, e);
-	}
-	i2++;
+        if (e == item) {
+            continue;
+        }
+        if (i1 != i2) {
+            rb_ary_store(ary, i2, e);
+        }
+        i2++;
     }
     if (RARRAY_LEN(ary) == i2) {
-	return;
+        return;
     }
 
     ary_resize_smaller(ary, i2);
@@ -4402,8 +4235,8 @@ rb_ary_delete_at(VALUE ary, long pos)
 
     if (pos >= len) return Qnil;
     if (pos < 0) {
-	pos += len;
-	if (pos < 0) return Qnil;
+        pos += len;
+        if (pos < 0) return Qnil;
     }
 
     rb_ary_modify(ary);
@@ -4420,39 +4253,23 @@ rb_ary_delete_at(VALUE ary, long pos)
  *  call-seq:
  *    array.delete_at(index) -> deleted_object or nil
  *
- *  Deletes an element from +self+, per the given +index+.
- *
- *  The given +index+ must be an
- *  {Integer-convertible object}[doc/implicit_conversion_rdoc.html#label-Integer-Convertible+Objects].
- *
- *  ---
+ *  Deletes an element from +self+, per the given \Integer +index+.
  *
  *  When +index+ is non-negative, deletes the element at offset +index+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.delete_at(1) # => "bar"
  *    a # => [:foo, 2]
  *
- *  If index is too large, returns nil:
- *    a = [:foo, 'bar', 2]
- *    a.delete_at(5) # => nil
- *
- *  ---
+ *  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:
- *    a = [:foo, 'bar', 2]
- *    a.delete_at(-5) # => nil
- *
- *  ---
- *
- *  Raises an exception if index is not an Integer-convertible object:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.delete_at(:foo)
+ *  If +index+ is too small (far from zero), returns nil.
  */
 
 static VALUE
@@ -4478,7 +4295,7 @@ ary_slice_bang_by_rb_ary_splice(VALUE ary, long pos, long len)
     else if (orig_len < pos) {
         return Qnil;
     }
-    else if (orig_len < pos + len) {
+    if (orig_len < pos + len) {
         len = orig_len - pos;
     }
     if (len == 0) {
@@ -4486,7 +4303,6 @@ ary_slice_bang_by_rb_ary_splice(VALUE ary, long pos, long len)
     }
     else {
         VALUE arg2 = rb_ary_new4(len, RARRAY_CONST_PTR_TRANSIENT(ary)+pos);
-        RBASIC_SET_CLASS(arg2, rb_obj_class(ary));
         rb_ary_splice(ary, pos, len, 0, 0);
         return arg2;
     }
@@ -4494,109 +4310,71 @@ ary_slice_bang_by_rb_ary_splice(VALUE ary, long pos, long len)
 
 /*
  *  call-seq:
- *    array.slice!(n) -> obj or nil
+ *    array.slice!(n) -> object or nil
  *    array.slice!(start, length) -> new_array or nil
  *    array.slice!(range) -> new_array or nil
  *
  *  Removes and returns elements from +self+.
  *
- *  - Argument +n+, if given must be an \Integer object.
- *  - Arguments +start+ and +length+, if given must be \Integer objects.
- *  - Argument +range+, if given, must be a \Range object.
- *
- *  ---
- *
  *  When the only argument is an \Integer +n+,
  *  removes and returns the _nth_ element in +self+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.slice!(1) # => "bar"
  *    a # => [:foo, 2]
  *
  *  If +n+ is negative, counts backwards from the end of +self+:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.slice!(-1) # => 2
  *    a # => [:foo, "bar"]
  *
- *  If +n+ is out of range, returns +nil+:
- *    a = [:foo, 'bar', 2]
- *    a.slice!(50) # => nil
- *    a.slice!(-50) # => nil
- *    a # => [:foo, "bar", 2]
- *
- *  ---
+ *  If +n+ 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:
+ *  returns the deleted objects in a new \Array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.slice!(0, 2) # => [:foo, "bar"]
  *    a # => [2]
  *
  *  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]
  *
  *  If <tt>start == a.size</tt> and +length+ is non-negative,
- *  returns a new empty \Array:
- *    a = [:foo, 'bar', 2]
- *    a.slice!(a.size, 0) # => []
- *    a.slice!(a.size, 50) # => []
- *    a # => [:foo, "bar", 2]
+ *  returns a new empty \Array.
  *
- *  If +length+ is negative, returns +nil+:
- *    a = [:foo, 'bar', 2]
- *    a.slice!(2, -1) # => nil
- *    a.slice!(1, -2) # => nil
- *    a # => [:foo, "bar", 2]
- *
- *  ---
+ *  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:
+ *
  *    a = [:foo, 'bar', 2]
- *     a.slice!(1..2) # => ["bar", 2]
+ *    a.slice!(1..2) # => ["bar", 2]
  *    a # => [:foo]
  *
- *  If <tt>range.start == a.size</tt>, returns a new empty \Array:
- *    a = [:foo, 'bar', 2]
- *    a.slice!(a.size..0) # => []
- *    a.slice!(a.size..50) # => []
- *    a.slice!(a.size..-1) # => []
- *    a.slice!(a.size..-50) # => []
- *    a # => [:foo, "bar", 2]
+ *  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 = [:foo, 'bar', 2]
- *    a.slice!(4..1) # => nil
- *    a.slice!(4..0) # => nil
- *    a.slice!(4..-1) # => nil
+ *  If <tt>range.start</tt> is larger than the array size, returns +nil+.
  *
  *  If <tt>range.end</tt> is negative, counts backwards from the end of the array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.slice!(0..-2) # => [:foo, "bar"]
  *    a # => [2]
  *
  *  If <tt>range.start</tt> is negative,
  *  calculates the start index backwards from the end of the array:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.slice!(-2..2) # => ["bar", 2]
  *    a # => [:foo]
  *
- *  ---
- *
- *  Raises an exception if given a single argument that is not an \Integer or a \Range:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.slice!(:foo)
- *
- *  Raises an exception if given two arguments that are not both Integers:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.slice!(:foo, 3)
- *    # Raises TypeError (no implicit conversion of Symbol into Integer):
- *    a.slice!(1, :bar)
  */
 
 static VALUE
@@ -4610,23 +4388,23 @@ rb_ary_slice_bang(int argc, VALUE *argv, VALUE ary)
     arg1 = argv[0];
 
     if (argc == 2) {
-	pos = NUM2LONG(argv[0]);
-	len = NUM2LONG(argv[1]);
+        pos = NUM2LONG(argv[0]);
+        len = NUM2LONG(argv[1]);
         return ary_slice_bang_by_rb_ary_splice(ary, pos, len);
     }
 
     if (!FIXNUM_P(arg1)) {
-	switch (rb_range_beg_len(arg1, &pos, &len, RARRAY_LEN(ary), 0)) {
-	  case Qtrue:
-	    /* valid range */
+        switch (rb_range_beg_len(arg1, &pos, &len, RARRAY_LEN(ary), 0)) {
+          case Qtrue:
+            /* valid range */
             return ary_slice_bang_by_rb_ary_splice(ary, pos, len);
-	  case Qnil:
-	    /* invalid range */
-	    return Qnil;
-	  default:
-	    /* not a range */
-	    break;
-	}
+          case Qnil:
+            /* invalid range */
+            return Qnil;
+          default:
+            /* not a range */
+            break;
+        }
     }
 
     return rb_ary_delete_at(ary, NUM2LONG(arg1));
@@ -4638,11 +4416,11 @@ ary_reject(VALUE orig, VALUE result)
     long i;
 
     for (i = 0; i < RARRAY_LEN(orig); i++) {
-	VALUE v = RARRAY_AREF(orig, i);
+        VALUE v = RARRAY_AREF(orig, i);
 
         if (!RTEST(rb_yield(v))) {
-	    rb_ary_push(result, v);
-	}
+            rb_ary_push(result, v);
+        }
     }
     return result;
 }
@@ -4655,12 +4433,12 @@ reject_bang_i(VALUE a)
     long i1, i2;
 
     for (i1 = i2 = 0; i1 < RARRAY_LEN(ary); arg->len[0] = ++i1) {
-	VALUE v = RARRAY_AREF(ary, i1);
-	if (RTEST(rb_yield(v))) continue;
-	if (i1 != i2) {
-	    rb_ary_store(ary, i2, v);
-	}
-	arg->len[1] = ++i2;
+        VALUE v = RARRAY_AREF(ary, i1);
+        if (RTEST(rb_yield(v))) continue;
+        if (i1 != i2) {
+            rb_ary_store(ary, i2, v);
+        }
+        arg->len[1] = ++i2;
     }
     return (i1 == i2) ? Qnil : ary;
 }
@@ -4683,18 +4461,17 @@ ary_reject_bang(VALUE ary)
  *  Removes each element for which the block returns a truthy value.
  *
  *  Returns +self+ if any elements removed:
+ *
  *    a = [:foo, 'bar', 2, 'bat']
- *    a1 = a.reject! {|element| element.to_s.start_with?('b') }
- *    a1 # => [:foo, 2]
- *    a1.equal?(a) # => true # Returned self
+ *    a.reject! {|element| element.to_s.start_with?('b') } # => [:foo, 2]
  *
- *  Returns +nil+ if no elements removed:
- *    a = [:foo, 'bar', 2]
- *    a.reject! {|element| false } # => nil
+ *  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!>
+ *
  */
 
 static VALUE
@@ -4712,13 +4489,16 @@ rb_ary_reject_bang(VALUE ary)
  *
  *  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 = 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>
+ *
  */
 
 static VALUE
@@ -4739,15 +4519,16 @@ rb_ary_reject(VALUE ary)
  *
  *  Removes each element in +self+ for which the block returns a truthy value;
  *  returns +self+:
+ *
  *    a = [:foo, 'bar', 2, 'bat']
- *    a1 = a.delete_if {|element| element.to_s.start_with?('b') }
- *    a1 # => [:foo, 2]
- *    a1.equal?(a) # => true # Returned self
+ *    a.delete_if {|element| element.to_s.start_with?('b') } # => [:foo, 2]
  *
  *  Returns a new \Enumerator if no block given:
+ *
  *    a = [:foo, 'bar', 2]
  *    a.delete_if # => #<Enumerator: [:foo, "bar", 2]:delete_if>
- */
+ *
+3 */
 
 static VALUE
 rb_ary_delete_if(VALUE ary)
@@ -4762,10 +4543,9 @@ static VALUE
 take_i(RB_BLOCK_CALL_FUNC_ARGLIST(val, cbarg))
 {
     VALUE *args = (VALUE *)cbarg;
-    if (args[1] == 0) rb_iter_break();
-    else args[1]--;
     if (argc > 1) val = rb_ary_new4(argc, argv);
     rb_ary_push(args[0], val);
+    if (--args[1] == 0) rb_iter_break();
     return Qnil;
 }
 
@@ -4775,12 +4555,13 @@ take_items(VALUE obj, long n)
     VALUE result = rb_check_array_type(obj);
     VALUE args[2];
 
+    if (n == 0) return result;
     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)
-	rb_raise(rb_eTypeError, "wrong argument type %"PRIsVALUE" (must respond to :each)",
-		 rb_obj_class(obj));
+    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;
 }
 
@@ -4790,20 +4571,17 @@ take_items(VALUE obj, long n)
  *    array.zip(*other_arrays) -> new_array
  *    array.zip(*other_arrays) {|other_array| ... } -> nil
  *
- *  Each object in +other_arrays+ must be an
- *  {Array-convertible object}[doc/implicit_conversion_rdoc.html#label-Array-Convertible+Objects].
- *
- *  ---
- *
  *  When no block given, returns a new \Array +new_array+ of size <tt>self.size</tt>
  *  whose elements are Arrays.
  *
  *  Each nested array <tt>new_array[n]</tt> is of size <tt>other_arrays.size+1</tt>,
  *  and contains:
+ *
  *  - The _nth_ element of +self+.
  *  - The _nth_ element of each of the +other_arrays+.
  *
  *  If all +other_arrays+ and +self+ are the same size:
+ *
  *    a = [:a0, :a1, :a2, :a3]
  *    b = [:b0, :b1, :b2, :b3]
  *    c = [:c0, :c1, :c2, :c3]
@@ -4812,6 +4590,7 @@ take_items(VALUE obj, long n)
  *
  *  If any array in +other_arrays+ is smaller than +self+,
  *  fills to <tt>self.size</tt> with +nil+:
+ *
  *    a = [:a0, :a1, :a2, :a3]
  *    b = [:b0, :b1, :b2]
  *    c = [:c0, :c1]
@@ -4820,34 +4599,27 @@ take_items(VALUE obj, long n)
  *
  *  If any array in +other_arrays+ is larger than +self+,
  *  its trailing elements are ignored:
+ *
  *    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]]
  *
- *  ---
+ *  When a block is given, calls the block with each of the sub-arrays (formed as above); returns +nil+:
  *
- *  When a block is given, calls the block with each of the sub-arrays (formed as above); returns nil
  *    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]
  *
- *  ---
- *
- *  Raises an exception if any object in +other_arrays+ is not an Array-convertible object:
- *    a = [:a0, :a1, :a2, :a3]
- *    b = [:b0, :b1, :b2, :b3]
- *    c = [:c0, :c1, :c2, :c3]
- *    # Raises TypeError (wrong argument type Symbol (must respond to :each)):
- *    d = a.zip(a, b, c, :foo)
  */
 
 static VALUE
@@ -4858,51 +4630,51 @@ rb_ary_zip(int argc, VALUE *argv, VALUE ary)
     VALUE result = Qnil;
 
     for (i=0; i<argc; i++) {
-	argv[i] = take_items(argv[i], len);
+        argv[i] = take_items(argv[i], len);
     }
 
     if (rb_block_given_p()) {
-	int arity = rb_block_arity();
-
-	if (arity > 1) {
-	    VALUE work, *tmp;
-
-	    tmp = ALLOCV_N(VALUE, work, argc+1);
-
-	    for (i=0; i<RARRAY_LEN(ary); i++) {
-		tmp[0] = RARRAY_AREF(ary, i);
-		for (j=0; j<argc; j++) {
-		    tmp[j+1] = rb_ary_elt(argv[j], i);
-		}
-		rb_yield_values2(argc+1, tmp);
-	    }
-
-	    if (work) ALLOCV_END(work);
-	}
-	else {
-	    for (i=0; i<RARRAY_LEN(ary); i++) {
-		VALUE tmp = rb_ary_new2(argc+1);
-
-		rb_ary_push(tmp, RARRAY_AREF(ary, i));
-		for (j=0; j<argc; j++) {
-		    rb_ary_push(tmp, rb_ary_elt(argv[j], i));
-		}
-		rb_yield(tmp);
-	    }
-	}
+        int arity = rb_block_arity();
+
+        if (arity > 1) {
+            VALUE work, *tmp;
+
+            tmp = ALLOCV_N(VALUE, work, argc+1);
+
+            for (i=0; i<RARRAY_LEN(ary); i++) {
+                tmp[0] = RARRAY_AREF(ary, i);
+                for (j=0; j<argc; j++) {
+                    tmp[j+1] = rb_ary_elt(argv[j], i);
+                }
+                rb_yield_values2(argc+1, tmp);
+            }
+
+            if (work) ALLOCV_END(work);
+        }
+        else {
+            for (i=0; i<RARRAY_LEN(ary); i++) {
+                VALUE tmp = rb_ary_new2(argc+1);
+
+                rb_ary_push(tmp, RARRAY_AREF(ary, i));
+                for (j=0; j<argc; j++) {
+                    rb_ary_push(tmp, rb_ary_elt(argv[j], i));
+                }
+                rb_yield(tmp);
+            }
+        }
     }
     else {
-	result = rb_ary_new_capa(len);
+        result = rb_ary_new_capa(len);
 
-	for (i=0; i<len; i++) {
-	    VALUE tmp = rb_ary_new_capa(argc+1);
+        for (i=0; i<len; i++) {
+            VALUE tmp = rb_ary_new_capa(argc+1);
 
-	    rb_ary_push(tmp, RARRAY_AREF(ary, i));
-	    for (j=0; j<argc; j++) {
-		rb_ary_push(tmp, rb_ary_elt(argv[j], i));
-	    }
-	    rb_ary_push(result, tmp);
-	}
+            rb_ary_push(tmp, RARRAY_AREF(ary, i));
+            for (j=0; j<argc; j++) {
+                rb_ary_push(tmp, rb_ary_elt(argv[j], i));
+            }
+            rb_ary_push(result, tmp);
+        }
     }
 
     return result;
@@ -4912,25 +4684,12 @@ rb_ary_zip(int argc, VALUE *argv, VALUE ary)
  *  call-seq:
  *    array.transpose -> new_array
  *
- *  Transposes the rows and columns in an array of arrays.
- *
- *  Each element in +self+ must be an
- *  {Array-convertible object}[doc/implicit_conversion_rdoc.html#label-Array-Convertible+Objects].
+ *  Transposes the rows and columns in an \Array of Arrays;
+ *  the nested Arrays must all be the same size:
  *
  *    a = [[:a0, :a1], [:b0, :b1], [:c0, :c1]]
  *    a.transpose # => [[:a0, :b0, :c0], [:a1, :b1, :c1]]
  *
- *  ---
- *
- *  Raises an exception if any element in +self+ is not an Array-convertible object:
- *    a = [[:a0, :a1], [:b0, :b1], :foo]
- *    # Raises TypeError (no implicit conversion of Symbol into Array):
- *    a.transpose
- *
- *  Raises an exception if the elements in +self+ are of differing sizes:
- *    a = [[:a0, :a1], [:b0, :b1], [:c0, :c1, :c2]]
- *    # Raises IndexError (element size differs (3 should be 2)):
- *    a.transpose
  */
 
 static VALUE
@@ -4942,21 +4701,21 @@ rb_ary_transpose(VALUE ary)
     alen = RARRAY_LEN(ary);
     if (alen == 0) return rb_ary_dup(ary);
     for (i=0; i<alen; i++) {
-	tmp = to_ary(rb_ary_elt(ary, i));
-	if (elen < 0) {		/* first element */
-	    elen = RARRAY_LEN(tmp);
-	    result = rb_ary_new2(elen);
-	    for (j=0; j<elen; j++) {
-		rb_ary_store(result, j, rb_ary_new2(alen));
-	    }
-	}
-	else if (elen != RARRAY_LEN(tmp)) {
-	    rb_raise(rb_eIndexError, "element size differs (%ld should be %ld)",
-		     RARRAY_LEN(tmp), elen);
-	}
-	for (j=0; j<elen; j++) {
-	    rb_ary_store(rb_ary_elt(result, j), i, rb_ary_elt(tmp, j));
-	}
+        tmp = to_ary(rb_ary_elt(ary, i));
+        if (elen < 0) {		/* first element */
+            elen = RARRAY_LEN(tmp);
+            result = rb_ary_new2(elen);
+            for (j=0; j<elen; j++) {
+                rb_ary_store(result, j, rb_ary_new2(alen));
+            }
+        }
+        else if (elen != RARRAY_LEN(tmp)) {
+            rb_raise(rb_eIndexError, "element size differs (%ld should be %ld)",
+                     RARRAY_LEN(tmp), elen);
+        }
+        for (j=0; j<elen; j++) {
+            rb_ary_store(rb_ary_elt(result, j), i, rb_ary_elt(tmp, j));
+        }
     }
     return result;
 }
@@ -4965,31 +4724,11 @@ rb_ary_transpose(VALUE ary)
  *  call-seq:
  *    array.replace(other_array) -> self
  *
- *  Replaces the content of +self+ with the content of +other_array+; returns +self+.
- *
- *  Argument +other_array+ must be an
- *  {Array-convertible object}[doc/implicit_conversion_rdoc.html#label-Array-Convertible+Objects].
+ *  Replaces the content of +self+ with the content of +other_array+; returns +self+:
  *
- *  ---
- *
- *  Replaces the content of +self+ with the content of +other_array+:
  *    a = [:foo, 'bar', 2]
- *    a1 = a.replace(['foo', :bar, 3])
- *    a1 # => ["foo", :bar, 3]
- *    a1.equal?(a) # => true # Returned self
- *
- *  Ignores the size of +self+:
+ *    a.replace(['foo', :bar, 3]) # => ["foo", :bar, 3]
  *
- *    a = [:foo, 'bar', 2]
- *    a.replace([]) # => []
- *    a.replace([:foo, 'bar', 2]) # => [:foo, "bar", 2]
- *
- *  ---
- *
- *  Raises an exception if +other_array+ is not an Array-convertible object:
- *    a = [:foo, 'bar', 2]
- *    # Raises TypeError (no implicit conversion of Symbol into Array):
- *    a.replace(:foo)
  */
 
 VALUE
@@ -4999,31 +4738,35 @@ rb_ary_replace(VALUE copy, VALUE orig)
     orig = to_ary(orig);
     if (copy == orig) return copy;
 
-    if (RARRAY_LEN(orig) <= RARRAY_EMBED_LEN_MAX) {
-        VALUE shared_root = 0;
+    rb_ary_reset(copy);
 
-        if (ARY_OWNS_HEAP_P(copy)) {
-            ary_heap_free(copy);
-	}
-        else if (ARY_SHARED_P(copy)) {
-            shared_root = ARY_SHARED_ROOT(copy);
-            FL_UNSET_SHARED(copy);
-        }
-        FL_SET_EMBED(copy);
+    /* 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));
-        if (shared_root) {
-            rb_ary_decrement_share(shared_root);
-        }
-        ARY_SET_LEN(copy, RARRAY_LEN(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);
+
+        FL_UNSET_EMBED(copy);
+        ARY_SET_PTR(copy, ptr);
+        ARY_SET_LEN(copy, len);
+        ARY_SET_CAPA(copy, len);
+
+        // 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));
     }
+#endif
+    /* Otherwise, orig is on heap and copy does not have enough space to embed
+     * the contents of orig. */
     else {
         VALUE shared_root = ary_make_shared(orig);
-        if (ARY_OWNS_HEAP_P(copy)) {
-            ary_heap_free(copy);
-        }
-        else {
-            rb_ary_unshare_safe(copy);
-        }
         FL_UNSET_EMBED(copy);
         ARY_SET_PTR(copy, ARY_HEAP_PTR(orig));
         ARY_SET_LEN(copy, ARY_HEAP_LEN(orig));
@@ -5038,10 +4781,10 @@ rb_ary_replace(VALUE copy, VALUE orig)
  *     array.clear -> self
  *
  *  Removes all elements from +self+:
+ *
  *    a = [:foo, 'bar', 2]
- *    a1 = a.clear
- *    a1 # => []
- *    a1.equal?(a) # => true # Returned self
+ *    a.clear # => []
+ *
  */
 
 VALUE
@@ -5049,11 +4792,11 @@ 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);
+        if (!ARY_EMBED_P(ary)) {
+            rb_ary_unshare(ary);
+            FL_SET_EMBED(ary);
             ARY_SET_EMBED_LEN(ary, 0);
-	}
+        }
     }
     else {
         ARY_SET_LEN(ary, 0);
@@ -5067,32 +4810,198 @@ rb_ary_clear(VALUE ary)
 
 /*
  *  call-seq:
- *     ary.fill(obj)                                 -> ary
- *     ary.fill(obj, start [, length])               -> ary
- *     ary.fill(obj, range)                          -> ary
- *     ary.fill {|index| block}                      -> ary
- *     ary.fill(start [, length]) {|index| block}    -> ary
- *     ary.fill(range) {|index| block}               -> ary
+ *    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]
+ *
+ *  With arguments +obj+ and \Integer +start+, and no block given,
+ *  replaces elements based on the given start.
+ *
+ *  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"]
+ *
+ *  If +start+ is negative, counts from the end (starting index is <tt>start + array.size</tt>):
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(:X, -2) # => ["a", "b", :X, :X]
+ *
+ *  If +start+ is too small (less than and far from zero), replaces all elements:
+ *
+ *    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]
+ *
+ *  With arguments +obj+, \Integer +start+, and \Integer +length+, and no block given,
+ *  replaces elements based on the given +start+ and +length+.
+ *
+ *  If +start+ is in range, replaces +length+ elements beginning at offset +start+:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(:X, 1, 1) # => ["a", :X, "c", "d"]
+ *
+ *  If +start+ is negative, counts from the end:
  *
- *  The first three forms set the selected elements of +self+ (which
- *  may be the entire array) to +obj+.
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(:X, -2, 1) # => ["a", "b", :X, "d"]
  *
- *  A +start+ of +nil+ is equivalent to zero.
+ *  If +start+ is large (<tt>start >= array.size</tt>), extends +self+ with +nil+:
  *
- *  A +length+ of +nil+ is equivalent to the length of the array.
+ *    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]
  *
- *  The last three forms fill the array with the value of the given block,
- *  which is passed the absolute index of each element to be filled.
+ *  If +length+ is zero or negative, replaces no elements:
  *
- *  Negative values of +start+ count from the end of the array, where +-1+ is
- *  the last element.
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(:X, 1, 0) # => ["a", "b", "c", "d"]
+ *    a.fill(:X, 1, -1) # => ["a", "b", "c", "d"]
+ *
+ *  With arguments +obj+ and \Range +range+, and no block given,
+ *  replaces elements based on the given range.
+ *
+ *  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 = ['a', 'b', 'c', 'd']
+ *    a.fill(:X, (1..1)) # => ["a", :X, "c", "d"]
+ *
+ *  If <tt>range.first</tt> is negative, replaces no elements:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(:X, (-1..1)) # => ["a", "b", "c", "d"]
+ *
+ *  If <tt>range.last</tt> is negative, counts from the end:
+ *
+ *    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"]
+ *
+ *  If <tt>range.last</tt> and <tt>range.last</tt> are both negative,
+ *  both count from the end of the array:
+ *
+ *    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"]
+ *
+ *  With no arguments and a block given, calls the block with each index;
+ *  replaces the corresponding element with the block's return value:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill { |index| "new_#{index}" } # => ["new_0", "new_1", "new_2", "new_3"]
+ *
+ *  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 in range (<tt>0 <= start < array.size</tt>),
+ *  replaces from offset +start+ to the end:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(1) { |index| "new_#{index}" } # => ["a", "new_1", "new_2", "new_3"]
+ *
+ *  If +start+ is too large(<tt>start >= array.size</tt>), does nothing:
+ *
+ *    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"]
+ *
+ *  If +start+ is negative, counts from the end:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(-2) { |index| "new_#{index}" } # => ["a", "b", "new_2", "new_3"]
+ *
+ *  If start is too small (<tt>start <= -array.size</tt>, replaces all elements:
+ *
+ *    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"]
+ *
+ *  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.
+ *
+ *  If +start+ is in range, replaces +length+ elements beginning at offset +start+:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(1, 1) { |index| "new_#{index}" } # => ["a", "new_1", "c", "d"]
+ *
+ *  If start is negative, counts from the end:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(-2, 1) { |index| "new_#{index}" } # => ["a", "b", "new_2", "d"]
+ *
+ *  If +start+ is large (<tt>start >= array.size</tt>), extends +self+ with +nil+:
+ *
+ *    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 +length+ is zero or less, replaces no elements:
+ *
+ *    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"]
+ *
+ *  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.
+ *
+ *  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 = ['a', 'b', 'c', 'd']
+ *    a.fill(1..1) { |index| "new_#{index}" } # => ["a", "new_1", "c", "d"]
+ *
+ *  If +range.first+ is negative, does nothing:
+ *
+ *    a = ['a', 'b', 'c', 'd']
+ *    a.fill(-1..1) { |index| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
+ *
+ *  If <tt>range.last</tt> is negative, counts from the end:
+ *
+ *    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"]
+ *
+ *  If <tt>range.first</tt> and <tt>range.last</tt> are both negative,
+ *  both count from the end:
+ *
+ *    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 = [ "a", "b", "c", "d" ]
- *     a.fill("x")              #=> ["x", "x", "x", "x"]
- *     a.fill("z", 2, 2)        #=> ["x", "x", "z", "z"]
- *     a.fill("y", 0..1)        #=> ["y", "y", "z", "z"]
- *     a.fill {|i| i*i}         #=> [0, 1, 4, 9]
- *     a.fill(-2) {|i| i*i*i}   #=> [0, 1, 8, 27]
  */
 
 static VALUE
@@ -5102,84 +5011,74 @@ rb_ary_fill(int argc, VALUE *argv, VALUE ary)
     long beg = 0, end = 0, len = 0;
 
     if (rb_block_given_p()) {
-	rb_scan_args(argc, argv, "02", &arg1, &arg2);
-	argc += 1;		/* hackish */
+        rb_scan_args(argc, argv, "02", &arg1, &arg2);
+        argc += 1;		/* hackish */
     }
     else {
-	rb_scan_args(argc, argv, "12", &item, &arg1, &arg2);
+        rb_scan_args(argc, argv, "12", &item, &arg1, &arg2);
     }
     switch (argc) {
       case 1:
-	beg = 0;
-	len = RARRAY_LEN(ary);
-	break;
+        beg = 0;
+        len = RARRAY_LEN(ary);
+        break;
       case 2:
-	if (rb_range_beg_len(arg1, &beg, &len, RARRAY_LEN(ary), 1)) {
-	    break;
-	}
-	/* fall through */
+        if (rb_range_beg_len(arg1, &beg, &len, RARRAY_LEN(ary), 1)) {
+            break;
+        }
+        /* fall through */
       case 3:
-	beg = NIL_P(arg1) ? 0 : NUM2LONG(arg1);
-	if (beg < 0) {
-	    beg = RARRAY_LEN(ary) + beg;
-	    if (beg < 0) beg = 0;
-	}
-	len = NIL_P(arg2) ? RARRAY_LEN(ary) - beg : NUM2LONG(arg2);
-	break;
+        beg = NIL_P(arg1) ? 0 : NUM2LONG(arg1);
+        if (beg < 0) {
+            beg = RARRAY_LEN(ary) + beg;
+            if (beg < 0) beg = 0;
+        }
+        len = NIL_P(arg2) ? RARRAY_LEN(ary) - beg : NUM2LONG(arg2);
+        break;
     }
     rb_ary_modify(ary);
     if (len < 0) {
         return ary;
     }
     if (beg >= ARY_MAX_SIZE || len > ARY_MAX_SIZE - beg) {
-	rb_raise(rb_eArgError, "argument too big");
+        rb_raise(rb_eArgError, "argument too big");
     }
     end = beg + len;
     if (RARRAY_LEN(ary) < end) {
-	if (end >= ARY_CAPA(ary)) {
-	    ary_resize_capa(ary, end);
-	}
-	ary_mem_clear(ary, RARRAY_LEN(ary), end - RARRAY_LEN(ary));
-	ARY_SET_LEN(ary, end);
+        if (end >= ARY_CAPA(ary)) {
+            ary_resize_capa(ary, end);
+        }
+        ary_mem_clear(ary, RARRAY_LEN(ary), end - RARRAY_LEN(ary));
+        ARY_SET_LEN(ary, end);
     }
 
-    if (item == Qundef) {
-	VALUE v;
-	long i;
+    if (UNDEF_P(item)) {
+        VALUE v;
+        long i;
 
-	for (i=beg; i<end; i++) {
-	    v = rb_yield(LONG2NUM(i));
-	    if (i>=RARRAY_LEN(ary)) break;
-	    ARY_SET(ary, i, v);
-	}
+        for (i=beg; i<end; i++) {
+            v = rb_yield(LONG2NUM(i));
+            if (i>=RARRAY_LEN(ary)) break;
+            ARY_SET(ary, i, v);
+        }
     }
     else {
-	ary_memfill(ary, beg, len, item);
+        ary_memfill(ary, beg, len, item);
     }
     return ary;
 }
 
 /*
  *  call-seq:
- *     ary + other_ary   -> new_ary
+ *    array + other_array -> new_array
  *
- *  Concatenation --- Returns a new array built by concatenating the
- *  two arrays together to produce a third array.
+ *  Returns a new \Array containing all elements of +array+
+ *  followed by all elements of +other_array+:
  *
- *     [ 1, 2, 3 ] + [ 4, 5 ]    #=> [ 1, 2, 3, 4, 5 ]
- *     a = [ "a", "b", "c" ]
- *     c = a + [ "d", "e", "f" ]
- *     c                         #=> [ "a", "b", "c", "d", "e", "f" ]
- *     a                         #=> [ "a", "b", "c" ]
+ *    a = [0, 1] + [2, 3]
+ *    a # => [0, 1, 2, 3]
  *
- *  Note that
- *     x += y
- *  is the same as
- *     x = x + y
- *  This means that it produces a new array. As a consequence,
- *  repeated use of <code>+=</code> on arrays can be quite inefficient.
- *
- *  See also Array#concat.
+ *  Related: #concat.
  */
 
 VALUE
@@ -5207,27 +5106,18 @@ ary_append(VALUE x, VALUE y)
     if (n > 0) {
         rb_ary_splice(x, RARRAY_LEN(x), 0, RARRAY_CONST_PTR_TRANSIENT(y), n);
     }
+    RB_GC_GUARD(y);
     return x;
 }
 
 /*
  *  call-seq:
- *     ary.concat(other_ary1, other_ary2, ...)   -> ary
- *
- *  Appends the elements of <code>other_ary</code>s to +self+.
- *
- *     [ "a", "b" ].concat( ["c", "d"])   #=> [ "a", "b", "c", "d" ]
- *     [ "a" ].concat( ["b"], ["c", "d"]) #=> [ "a", "b", "c", "d" ]
- *     [ "a" ].concat #=> [ "a" ]
+ *    array.concat(*other_arrays) -> self
  *
- *     a = [ 1, 2, 3 ]
- *     a.concat( [ 4, 5 ])
- *     a                                 #=> [ 1, 2, 3, 4, 5 ]
- *
- *     a = [ 1, 2 ]
- *     a.concat(a, a)                    #=> [1, 2, 1, 2, 1, 2]
+ *  Adds to +array+ all elements from each \Array in +other_arrays+; returns +self+:
  *
- *  See also Array#+.
+ *    a = [0, 1]
+ *    a.concat([2, 3], [4, 5]) # => [0, 1, 2, 3, 4, 5]
  */
 
 static VALUE
@@ -5236,15 +5126,15 @@ rb_ary_concat_multi(int argc, VALUE *argv, VALUE ary)
     rb_ary_modify_check(ary);
 
     if (argc == 1) {
-	rb_ary_concat(ary, argv[0]);
+        rb_ary_concat(ary, argv[0]);
     }
     else if (argc > 1) {
-	int i;
-	VALUE args = rb_ary_tmp_new(argc);
-	for (i = 0; i < argc; i++) {
-	    rb_ary_concat(args, argv[i]);
-	}
-	ary_append(ary, args);
+        int i;
+        VALUE args = rb_ary_hidden_new(argc);
+        for (i = 0; i < argc; i++) {
+            rb_ary_concat(args, argv[i]);
+        }
+        ary_append(ary, args);
     }
 
     ary_verify(ary);
@@ -5259,18 +5149,19 @@ rb_ary_concat(VALUE x, VALUE y)
 
 /*
  *  call-seq:
- *     ary * int     -> new_ary
- *     ary * str     -> new_string
+ *    array * n -> new_array
+ *    array * string_separator -> new_string
  *
- *  Repetition --- With a String argument, equivalent to
- *  <code>ary.join(str)</code>.
+ *  When non-negative argument \Integer +n+ is given,
+ *  returns a new \Array built by concatenating the +n+ copies of +self+:
  *
- *  Otherwise, returns a new array built by concatenating the +int+ 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>:
  *
- *     [ 1, 2, 3 ] * 3    #=> [ 1, 2, 3, 1, 2, 3, 1, 2, 3 ]
- *     [ 1, 2, 3 ] * ","  #=> "1,2,3"
+ *    [0, [0, 1], {foo: 0}] * ', ' # => "0, 0, 1, {:foo=>0}"
  *
  */
 
@@ -5283,30 +5174,30 @@ rb_ary_times(VALUE ary, VALUE times)
 
     tmp = rb_check_string_type(times);
     if (!NIL_P(tmp)) {
-	return rb_ary_join(ary, tmp);
+        return rb_ary_join(ary, tmp);
     }
 
     len = NUM2LONG(times);
     if (len == 0) {
-	ary2 = ary_new(rb_obj_class(ary), 0);
-	goto out;
+        ary2 = ary_new(rb_cArray, 0);
+        goto out;
     }
     if (len < 0) {
-	rb_raise(rb_eArgError, "negative argument");
+        rb_raise(rb_eArgError, "negative argument");
     }
     if (ARY_MAX_SIZE/len < RARRAY_LEN(ary)) {
-	rb_raise(rb_eArgError, "argument too big");
+        rb_raise(rb_eArgError, "argument too big");
     }
     len *= RARRAY_LEN(ary);
 
-    ary2 = ary_new(rb_obj_class(ary), len);
+    ary2 = ary_new(rb_cArray, len);
     ARY_SET_LEN(ary2, len);
 
     ptr = RARRAY_CONST_PTR_TRANSIENT(ary);
     t = RARRAY_LEN(ary);
     if (0 < t) {
-	ary_memcpy(ary2, 0, t, ptr);
-	while (t <= len/2) {
+        ary_memcpy(ary2, 0, t, ptr);
+        while (t <= len/2) {
             ary_memcpy(ary2, t, t, RARRAY_CONST_PTR_TRANSIENT(ary2));
             t *= 2;
         }
@@ -5320,22 +5211,17 @@ rb_ary_times(VALUE ary, VALUE times)
 
 /*
  *  call-seq:
- *     ary.assoc(obj)   -> element_ary  or  nil
+ *    array.assoc(obj) -> found_array or nil
  *
- *  Searches through an array whose elements are also arrays comparing +obj+
- *  with the first element of each contained array using <code>obj.==</code>.
+ *  Returns the first element in +self+ that is an \Array
+ *  whose first element <tt>==</tt> +obj+:
  *
- *  Returns the first contained array that matches (that is, the first
- *  associated array), or +nil+ if no match is found.
+ *    a = [{foo: 0}, [2, 4], [4, 5, 6], [4, 5]]
+ *    a.assoc(4) # => [4, 5, 6]
  *
- *  See also Array#rassoc
+ *  Returns +nil+ if no such element is found.
  *
- *     s1 = [ "colors", "red", "blue", "green" ]
- *     s2 = [ "letters", "a", "b", "c" ]
- *     s3 = "foo"
- *     a  = [ s1, s2, s3 ]
- *     a.assoc("letters")  #=> [ "letters", "a", "b", "c" ]
- *     a.assoc("foo")      #=> nil
+ *  Related: #rassoc.
  */
 
 VALUE
@@ -5345,30 +5231,27 @@ rb_ary_assoc(VALUE ary, VALUE key)
     VALUE v;
 
     for (i = 0; i < RARRAY_LEN(ary); ++i) {
-	v = rb_check_array_type(RARRAY_AREF(ary, i));
-	if (!NIL_P(v) && RARRAY_LEN(v) > 0 &&
-	    rb_equal(RARRAY_AREF(v, 0), key))
-	    return v;
+        v = rb_check_array_type(RARRAY_AREF(ary, i));
+        if (!NIL_P(v) && RARRAY_LEN(v) > 0 &&
+            rb_equal(RARRAY_AREF(v, 0), key))
+            return v;
     }
     return Qnil;
 }
 
 /*
  *  call-seq:
- *     ary.rassoc(obj) -> element_ary or nil
- *
- *  Searches through the array whose elements are also arrays.
+ *    array.rassoc(obj) -> found_array or nil
  *
- *  Compares +obj+ with the second element of each contained array using
- *  <code>obj.==</code>.
+ *  Returns the first element in +self+ that is an \Array
+ *  whose second element <tt>==</tt> +obj+:
  *
- *  Returns the first contained array that matches +obj+.
+ *    a = [{foo: 0}, [2, 4], [4, 5, 6], [4, 5]]
+ *    a.rassoc(4) # => [2, 4]
  *
- *  See also Array#assoc.
+ *  Returns +nil+ if no such element is found.
  *
- *     a = [ [ 1, "one"], [2, "two"], [3, "three"], ["ii", "two"] ]
- *     a.rassoc("two")    #=> [2, "two"]
- *     a.rassoc("four")   #=> nil
+ *  Related: #assoc.
  */
 
 VALUE
@@ -5378,11 +5261,11 @@ rb_ary_rassoc(VALUE ary, VALUE value)
     VALUE v;
 
     for (i = 0; i < RARRAY_LEN(ary); ++i) {
-	v = RARRAY_AREF(ary, i);
-	if (RB_TYPE_P(v, T_ARRAY) &&
-	    RARRAY_LEN(v) > 1 &&
-	    rb_equal(RARRAY_AREF(v, 1), value))
-	    return v;
+        v = RARRAY_AREF(ary, i);
+        if (RB_TYPE_P(v, T_ARRAY) &&
+            RARRAY_LEN(v) > 1 &&
+            rb_equal(RARRAY_AREF(v, 1), value))
+            return v;
     }
     return Qnil;
 }
@@ -5401,38 +5284,42 @@ recursive_equal(VALUE ary1, VALUE ary2, int recur)
     len1 = RARRAY_LEN(ary1);
 
     for (i = 0; i < len1; i++) {
-	if (*p1 != *p2) {
-	    if (rb_equal(*p1, *p2)) {
-		len1 = RARRAY_LEN(ary1);
-		if (len1 != RARRAY_LEN(ary2))
-		    return Qfalse;
-		if (len1 < i)
-		    return Qtrue;
+        if (*p1 != *p2) {
+            if (rb_equal(*p1, *p2)) {
+                len1 = RARRAY_LEN(ary1);
+                if (len1 != RARRAY_LEN(ary2))
+                    return Qfalse;
+                if (len1 < i)
+                    return Qtrue;
                 p1 = RARRAY_CONST_PTR(ary1) + i;
                 p2 = RARRAY_CONST_PTR(ary2) + i;
-	    }
-	    else {
-		return Qfalse;
-	    }
-	}
-	p1++;
-	p2++;
+            }
+            else {
+                return Qfalse;
+            }
+        }
+        p1++;
+        p2++;
     }
     return Qtrue;
 }
 
 /*
  *  call-seq:
- *     ary == other_ary   ->   bool
+ *    array == 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>:
  *
- *  Equality --- Two arrays are equal if they contain the same number of
- *  elements and if each element is equal to (according to Object#==) the
- *  corresponding element in +other_ary+.
+ *    a0 = [:foo, 'bar', 2]
+ *    a1 = [:foo, 'bar', 2.0]
+ *    a1 == a0 # => true
+ *    [] == [] # => true
  *
- *     [ "a", "c" ]    == [ "a", "c", 7 ]     #=> false
- *     [ "a", "c", 7 ] == [ "a", "c", 7 ]     #=> true
- *     [ "a", "c", 7 ] == [ "a", "d", "f" ]   #=> false
+ *  Otherwise, returns +false+.
  *
+ *  This method is different from method Array#eql?,
+ *  which compares elements using <tt>Object#eql?</tt>.
  */
 
 static VALUE
@@ -5440,10 +5327,10 @@ rb_ary_equal(VALUE ary1, VALUE ary2)
 {
     if (ary1 == ary2) return Qtrue;
     if (!RB_TYPE_P(ary2, T_ARRAY)) {
-	if (!rb_respond_to(ary2, idTo_ary)) {
-	    return Qfalse;
-	}
-	return rb_equal(ary2, ary1);
+        if (!rb_respond_to(ary2, idTo_ary)) {
+            return Qfalse;
+        }
+        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;
@@ -5457,18 +5344,27 @@ recursive_eql(VALUE ary1, VALUE ary2, int recur)
 
     if (recur) return Qtrue; /* Subtle! */
     for (i=0; i<RARRAY_LEN(ary1); i++) {
-	if (!rb_eql(rb_ary_elt(ary1, i), rb_ary_elt(ary2, i)))
-	    return Qfalse;
+        if (!rb_eql(rb_ary_elt(ary1, i), rb_ary_elt(ary2, i)))
+            return Qfalse;
     }
     return Qtrue;
 }
 
 /*
  *  call-seq:
- *     ary.eql?(other)  -> true or false
+ *    array.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>:
+ *
+ *    a0 = [:foo, 'bar', 2]
+ *    a1 = [:foo, 'bar', 2]
+ *    a1.eql?(a0) # => true
  *
- *  Returns +true+ if +self+ and +other+ are the same object,
- *  or are both arrays with the same content (according to Object#eql?).
+ *  Otherwise, returns +false+.
+ *
+ *  This method is different from method Array#==,
+ *  which compares using method <tt>Object#==</tt>.
  */
 
 static VALUE
@@ -5483,14 +5379,15 @@ rb_ary_eql(VALUE ary1, VALUE ary2)
 
 /*
  *  call-seq:
- *     ary.hash   -> integer
+ *    array.hash -> integer
+ *
+ *  Returns the integer hash value for +self+.
  *
- *  Compute a hash-code for this array.
+ *  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 code (and will
- *  compare using #eql?).
+ *    [0, 1, 2].hash == [0, 1, 2].hash # => true
+ *    [0, 1, 2].hash == [0, 1, 3].hash # => false
  *
- *  See also Object#hash.
  */
 
 static VALUE
@@ -5503,8 +5400,8 @@ rb_ary_hash(VALUE ary)
     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));
+        n = rb_hash(RARRAY_AREF(ary, i));
+        h = rb_hash_uint(h, NUM2LONG(n));
     }
     h = rb_hash_end(h);
     return ST2FIX(h);
@@ -5512,14 +5409,13 @@ rb_ary_hash(VALUE ary)
 
 /*
  *  call-seq:
- *     ary.include?(object)   -> true or false
+ *    array.include?(obj) -> true or false
  *
- *  Returns +true+ if the given +object+ is present in +self+ (that is, if any
- *  element <code>==</code> +object+), otherwise returns +false+.
+ *  Returns +true+ if for some index +i+ in +self+, <tt>obj == self[i]</tt>;
+ *  otherwise +false+:
  *
- *     a = [ "a", "b", "c" ]
- *     a.include?("b")   #=> true
- *     a.include?("z")   #=> false
+ *    [0, 1, 2].include?(2) # => true
+ *    [0, 1, 2].include?(3) # => false
  */
 
 VALUE
@@ -5529,10 +5425,10 @@ rb_ary_includes(VALUE ary, VALUE item)
     VALUE e;
 
     for (i=0; i<RARRAY_LEN(ary); i++) {
-	e = RARRAY_AREF(ary, i);
-	if (rb_equal(e, item)) {
-	    return Qtrue;
-	}
+        e = RARRAY_AREF(ary, i);
+        if (rb_equal(e, item)) {
+            return Qtrue;
+        }
     }
     return Qfalse;
 }
@@ -5544,10 +5440,10 @@ rb_ary_includes_by_eql(VALUE ary, VALUE item)
     VALUE e;
 
     for (i=0; i<RARRAY_LEN(ary); i++) {
-	e = RARRAY_AREF(ary, i);
-	if (rb_eql(item, e)) {
-	    return Qtrue;
-	}
+        e = RARRAY_AREF(ary, i);
+        if (rb_eql(item, e)) {
+            return Qtrue;
+        }
     }
     return Qfalse;
 }
@@ -5560,45 +5456,46 @@ recursive_cmp(VALUE ary1, VALUE ary2, int recur)
     if (recur) return Qundef;	/* Subtle! */
     len = RARRAY_LEN(ary1);
     if (len > RARRAY_LEN(ary2)) {
-	len = RARRAY_LEN(ary2);
+        len = RARRAY_LEN(ary2);
     }
     for (i=0; i<len; i++) {
-	VALUE e1 = rb_ary_elt(ary1, i), e2 = rb_ary_elt(ary2, i);
-	VALUE v = rb_funcallv(e1, id_cmp, 1, &e2);
-	if (v != INT2FIX(0)) {
-	    return v;
-	}
+        VALUE e1 = rb_ary_elt(ary1, i), e2 = rb_ary_elt(ary2, i);
+        VALUE v = rb_funcallv(e1, id_cmp, 1, &e2);
+        if (v != INT2FIX(0)) {
+            return v;
+        }
     }
     return Qundef;
 }
 
 /*
  *  call-seq:
- *     ary <=> other_ary   ->  -1, 0, +1 or nil
+ *    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>.
+ *
+ *  Returns -1 if any result is -1:
+ *
+ *    [0, 1, 2] <=> [0, 1, 3] # => -1
+ *
+ *  Returns 1 if any result is 1:
  *
- *  Comparison --- Returns an integer (+-1+, +0+, or <code>+1</code>) if this
- *  array is less than, equal to, or greater than +other_ary+.
+ *    [0, 1, 2] <=> [0, 1, 1] # => 1
  *
- *  Each object in each array is compared (using the <=> operator).
+ *  When all results are zero:
  *
- *  Arrays are compared in an "element-wise" manner; the first element of +ary+
- *  is compared with the first one of +other_ary+ using the <=> operator, then
- *  each of the second elements, etc...
- *  As soon as the result of any such comparison is non zero (i.e. the two
- *  corresponding elements are not equal), that result is returned for the
- *  whole array comparison.
+ *  - Returns -1 if +array+ is smaller than +other_array+:
  *
- *  If all the elements are equal, then the result is based on a comparison of
- *  the array lengths. Thus, two arrays are "equal" according to Array#<=> if,
- *  and only if, they have the same length and the value of each element is
- *  equal to the value of the corresponding element in the other array.
+ *      [0, 1, 2] <=> [0, 1, 2, 3] # => -1
  *
- *  +nil+ is returned if the +other_ary+ is not an array or if the comparison
- *  of two elements returned +nil+.
+ *  - Returns 1 if +array+ is larger than +other_array+:
  *
- *     [ "a", "a", "c" ]    <=> [ "a", "b", "c" ]   #=> -1
- *     [ 1, 2, 3, 4, 5, 6 ] <=> [ 1, 2 ]            #=> +1
- *     [ 1, 2 ]             <=> [ 1, :two ]         #=> nil
+ *      [0, 1, 2] <=> [0, 1] # => 1
+ *
+ *  - Returns 0 if +array+ and +other_array+ are the same size:
+ *
+ *      [0, 1, 2] <=> [0, 1, 2] # => 0
  *
  */
 
@@ -5612,7 +5509,7 @@ 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);
@@ -5625,8 +5522,8 @@ ary_add_hash(VALUE hash, VALUE ary)
     long i;
 
     for (i=0; i<RARRAY_LEN(ary); i++) {
-	VALUE elt = RARRAY_AREF(ary, i);
-	rb_hash_add_new_element(hash, elt, elt);
+        VALUE elt = RARRAY_AREF(ary, i);
+        rb_hash_add_new_element(hash, elt, elt);
     }
     return hash;
 }
@@ -5654,8 +5551,8 @@ ary_add_hash_by(VALUE hash, VALUE ary)
     long i;
 
     for (i = 0; i < RARRAY_LEN(ary); ++i) {
-	VALUE v = rb_ary_elt(ary, i), k = rb_yield(v);
-	rb_hash_add_new_element(hash, k, v);
+        VALUE v = rb_ary_elt(ary, i), k = rb_yield(v);
+        rb_hash_add_new_element(hash, k, v);
     }
     return hash;
 }
@@ -5673,35 +5570,28 @@ 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);
+        st_free_table(tbl);
         RHASH_ST_CLEAR(hash);
     }
 }
 
 /*
  *  call-seq:
- *     ary - other_ary    -> new_ary
- *
- *  Array Difference
- *
- *  Returns a new array that is a copy of the original array, removing all
- *  occurrences of any item that also appear in +other_ary+. The order is
- *  preserved from the original array.
- *
- *  It compares elements using their #hash and #eql? methods for efficiency.
+ *    array - other_array -> new_array
  *
- *     [ 1, 1, 2, 2, 3, 3, 4, 5 ] - [ 1, 2, 4 ]  #=>  [ 3, 3, 5 ]
+ *  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:
  *
- *  Note that while 1 and 2 were only present once in the array argument, and
- *  were present twice in the receiver array, all occurrences of each Integer are
- *  removed in the returned array.
+ *    [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]
  *
- *  If you need set-like behavior, see the library class Set.
- *
- *  See also Array#difference.
+ *  Related: Array#difference.
  */
 
-static VALUE
+VALUE
 rb_ary_diff(VALUE ary1, VALUE ary2)
 {
     VALUE ary3;
@@ -5709,21 +5599,22 @@ rb_ary_diff(VALUE ary1, VALUE ary2)
     long i;
 
     ary2 = to_ary(ary2);
+    if (RARRAY_LEN(ary2) == 0) { return ary_make_shared_copy(ary1); }
     ary3 = rb_ary_new();
 
     if (RARRAY_LEN(ary1) <= SMALL_ARRAY_LEN || RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) {
-	for (i=0; i<RARRAY_LEN(ary1); i++) {
-	    VALUE elt = rb_ary_elt(ary1, i);
-	    if (rb_ary_includes_by_eql(ary2, elt)) continue;
-	    rb_ary_push(ary3, elt);
-	}
-	return ary3;
+        for (i=0; i<RARRAY_LEN(ary1); i++) {
+            VALUE elt = rb_ary_elt(ary1, i);
+            if (rb_ary_includes_by_eql(ary2, elt)) continue;
+            rb_ary_push(ary3, elt);
+        }
+        return ary3;
     }
 
     hash = ary_make_hash(ary2);
     for (i=0; i<RARRAY_LEN(ary1); i++) {
         if (rb_hash_stlike_lookup(hash, RARRAY_AREF(ary1, i), NULL)) continue;
-	rb_ary_push(ary3, rb_ary_elt(ary1, i));
+        rb_ary_push(ary3, rb_ary_elt(ary1, i));
     }
     ary_recycle_hash(hash);
     return ary3;
@@ -5731,31 +5622,19 @@ rb_ary_diff(VALUE ary1, VALUE ary2)
 
 /*
  *  call-seq:
- *     ary.difference(other_ary1, other_ary2, ...)   -> new_ary
- *
- *  Array Difference
+ *    array.difference(*other_arrays) -> new_array
  *
- *  Returns a new array that is a copy of the original array, removing all
- *  occurrences of any item that also appear in +other_ary+. The order is
- *  preserved from the original array.
+ *  Returns a new \Array containing only those elements from +self+
+ *  that are not found in any of the Arrays +other_arrays+;
+ *  items are compared using <tt>eql?</tt>;  order from +self+ is preserved:
  *
- *  It compares elements using their #hash and #eql? methods for efficiency.
+ *    [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]
  *
- *     [ 1, 1, 2, 2, 3, 3, 4, 5 ].difference([ 1, 2, 4 ])     #=> [ 3, 3, 5 ]
+ *  Returns a copy of +self+ if no arguments given.
  *
- *  Note that while 1 and 2 were only present once in the array argument, and
- *  were present twice in the receiver array, all occurrences of each Integer are
- *  removed in the returned array.
- *
- *  Multiple array arguments can be supplied and all occurrences of any element
- *  in those supplied arrays that match the receiver will be removed from the
- *  returned array.
- *
- *     [ 1, 'c', :s, 'yep' ].difference([ 1 ], [ 'a', 'c' ])  #=> [ :s, "yep" ]
- *
- *  If you need set-like behavior, see the library class Set.
- *
- *  See also Array#-.
+ *  Related: Array#-.
  */
 
 static VALUE
@@ -5797,17 +5676,19 @@ rb_ary_difference_multi(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *     ary & other_ary      -> new_ary
+ *    array & 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>:
  *
- *  Set Intersection --- Returns a new array containing unique elements common to the
- *  two arrays. The order is preserved from the original array.
+ *    [0, 1, 2, 3] & [1, 2] # => [1, 2]
+ *    [0, 1, 0, 1] & [0, 1] # => [0, 1]
  *
- *  It compares elements using their #hash and #eql? methods for efficiency.
+ *  Preserves order from +array+:
  *
- *     [ 1, 1, 3, 5 ] & [ 3, 2, 1 ]                 #=> [ 1, 3 ]
- *     [ 'a', 'b', 'b', 'z' ] & [ 'a', 'b', 'c' ]   #=> [ 'a', 'b' ]
+ *    [0, 1, 2] & [3, 2, 1, 0] # => [0, 1, 2]
  *
- *  See also Array#uniq.
+ *  Related: Array#intersection.
  */
 
 
@@ -5823,23 +5704,23 @@ rb_ary_and(VALUE ary1, VALUE ary2)
     if (RARRAY_LEN(ary1) == 0 || RARRAY_LEN(ary2) == 0) return ary3;
 
     if (RARRAY_LEN(ary1) <= SMALL_ARRAY_LEN && RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) {
-	for (i=0; i<RARRAY_LEN(ary1); i++) {
-	    v = RARRAY_AREF(ary1, i);
-	    if (!rb_ary_includes_by_eql(ary2, v)) continue;
-	    if (rb_ary_includes_by_eql(ary3, v)) continue;
-	    rb_ary_push(ary3, v);
-	}
-	return ary3;
+        for (i=0; i<RARRAY_LEN(ary1); i++) {
+            v = RARRAY_AREF(ary1, i);
+            if (!rb_ary_includes_by_eql(ary2, v)) continue;
+            if (rb_ary_includes_by_eql(ary3, v)) continue;
+            rb_ary_push(ary3, v);
+        }
+        return ary3;
     }
 
     hash = ary_make_hash(ary2);
 
     for (i=0; i<RARRAY_LEN(ary1); i++) {
-	v = RARRAY_AREF(ary1, i);
-	vv = (st_data_t)v;
+        v = RARRAY_AREF(ary1, i);
+        vv = (st_data_t)v;
         if (rb_hash_stlike_delete(hash, &vv, 0)) {
-	    rb_ary_push(ary3, v);
-	}
+            rb_ary_push(ary3, v);
+        }
     }
     ary_recycle_hash(hash);
 
@@ -5848,19 +5729,22 @@ rb_ary_and(VALUE ary1, VALUE ary2)
 
 /*
  *  call-seq:
- *     ary.intersection(other_ary1, other_ary2, ...)      -> new_ary
+ *    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>:
  *
- *  Set Intersection --- Returns a new array containing unique elements common
- *  to +self+ and <code>other_ary</code>s. Order is preserved from the original
- *  array.
+ *    [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]
  *
- *  It compares elements using their #hash and #eql? methods for efficiency.
+ *  Preserves order from +self+:
  *
- *     [ 1, 1, 3, 5 ].intersection([ 3, 2, 1 ])                    # => [ 1, 3 ]
- *     [ "a", "b", "z" ].intersection([ "a", "b", "c" ], [ "b" ])  # => [ "b" ]
- *     [ "a" ].intersection #=> [ "a" ]
+ *    [0, 1, 2].intersection([2, 1, 0]) # => [0, 1, 2]
  *
- *  See also Array#&.
+ *  Returns a copy of +self+ if no arguments given.
+ *
+ *  Related: Array#&.
  */
 
 static VALUE
@@ -5909,17 +5793,17 @@ rb_ary_union_hash(VALUE hash, VALUE ary2)
 
 /*
  *  call-seq:
- *     ary | other_ary     -> new_ary
- *
- *  Set Union --- Returns a new array by joining +ary+ with +other_ary+,
- *  excluding any duplicates and preserving the order from the given arrays.
+ *    array | other_array -> new_array
  *
- *  It compares elements using their #hash and #eql? methods for efficiency.
+ *  Returns the union of +array+ and \Array +other_array+;
+ *  duplicates are removed; order is preserved;
+ *  items are compared using <tt>eql?</tt>:
  *
- *     [ "a", "b", "c" ] | [ "c", "d", "a" ]    #=> [ "a", "b", "c", "d" ]
- *     [ "c", "d", "a" ] | [ "a", "b", "c" ]    #=> [ "c", "d", "a", "b" ]
+ *    [0, 1] | [2, 3] # => [0, 1, 2, 3]
+ *    [0, 1, 1] | [2, 2, 3] # => [0, 1, 2, 3]
+ *    [0, 1, 2] | [3, 2, 1, 0] # => [0, 1, 2, 3]
  *
- *  See also Array#union.
+ *  Related: Array#union.
  */
 
 static VALUE
@@ -5929,10 +5813,10 @@ rb_ary_or(VALUE ary1, VALUE ary2)
 
     ary2 = to_ary(ary2);
     if (RARRAY_LEN(ary1) + RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) {
-	ary3 = rb_ary_new();
+        ary3 = rb_ary_new();
         rb_ary_union(ary3, ary1);
         rb_ary_union(ary3, ary2);
-	return ary3;
+        return ary3;
     }
 
     hash = ary_make_hash(ary1);
@@ -5945,18 +5829,18 @@ rb_ary_or(VALUE ary1, VALUE ary2)
 
 /*
  *  call-seq:
- *     ary.union(other_ary1, other_ary2, ...)   -> new_ary
+ *    array.union(*other_arrays) -> new_array
  *
- *  Set Union --- Returns a new array by joining <code>other_ary</code>s with +self+,
- *  excluding any duplicates and preserving the order from the given arrays.
+ *  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>:
  *
- *  It compares elements using their #hash and #eql? methods for efficiency.
+ *    [0, 1, 2, 3].union([4, 5], [6, 7]) # => [0, 1, 2, 3, 4, 5, 6, 7]
+ *    [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]
  *
- *     [ "a", "b", "c" ].union( [ "c", "d", "a" ] )    #=> [ "a", "b", "c", "d" ]
- *     [ "a" ].union( ["e", "b"], ["a", "c", "b"] )    #=> [ "a", "e", "b", "c" ]
- *     [ "a" ].union #=> [ "a" ]
+ *  Returns a copy of +self+ if no arguments given.
  *
- *  See also Array#|.
+ *  Related: Array#|.
  */
 
 static VALUE
@@ -5991,30 +5875,191 @@ rb_ary_union_multi(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *     ary.max                     -> obj
- *     ary.max {|a, b| block}      -> obj
- *     ary.max(n)                  -> array
- *     ary.max(n) {|a, b| block}   -> array
+ *     ary.intersect?(other_ary)   -> true or false
+ *
+ *  Returns +true+ if the array and +other_ary+ have at least one element in
+ *  common, otherwise returns +false+:
+ *
+ *     a = [ 1, 2, 3 ]
+ *     b = [ 3, 4, 5 ]
+ *     c = [ 5, 6, 7 ]
+ *     a.intersect?(b)   #=> true
+ *     a.intersect?(c)   #=> false
+ *
+ */
+
+static VALUE
+rb_ary_intersect_p(VALUE ary1, VALUE ary2)
+{
+    VALUE hash, v, result, shorter, longer;
+    st_data_t vv;
+    long i;
+
+    ary2 = to_ary(ary2);
+    if (RARRAY_LEN(ary1) == 0 || RARRAY_LEN(ary2) == 0) return Qfalse;
+
+    if (RARRAY_LEN(ary1) <= SMALL_ARRAY_LEN && RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) {
+        for (i=0; i<RARRAY_LEN(ary1); i++) {
+            v = RARRAY_AREF(ary1, i);
+            if (rb_ary_includes_by_eql(ary2, v)) return Qtrue;
+        }
+        return Qfalse;
+    }
+
+    shorter = ary1;
+    longer = ary2;
+    if (RARRAY_LEN(ary1) > RARRAY_LEN(ary2)) {
+        longer = ary1;
+        shorter = ary2;
+    }
+
+    hash = ary_make_hash(shorter);
+    result = Qfalse;
+
+    for (i=0; i<RARRAY_LEN(longer); i++) {
+        v = RARRAY_AREF(longer, i);
+        vv = (st_data_t)v;
+        if (rb_hash_stlike_lookup(hash, vv, 0)) {
+            result = Qtrue;
+            break;
+        }
+    }
+    ary_recycle_hash(hash);
+
+    return result;
+}
+
+static VALUE
+ary_max_generic(VALUE ary, long i, VALUE vmax)
+{
+    RUBY_ASSERT(i > 0 && i < RARRAY_LEN(ary));
+
+    VALUE v;
+    for (; i < RARRAY_LEN(ary); ++i) {
+        v = RARRAY_AREF(ary, i);
+
+        if (rb_cmpint(rb_funcallv(vmax, id_cmp, 1, &v), vmax, v) < 0) {
+            vmax = v;
+        }
+    }
+
+    return vmax;
+}
+
+static VALUE
+ary_max_opt_fixnum(VALUE ary, long i, VALUE vmax)
+{
+    const long n = RARRAY_LEN(ary);
+    RUBY_ASSERT(i > 0 && i < n);
+    RUBY_ASSERT(FIXNUM_P(vmax));
+
+    VALUE v;
+    for (; i < n; ++i) {
+        v = RARRAY_AREF(ary, i);
+
+        if (FIXNUM_P(v)) {
+            if ((long)vmax < (long)v) {
+                vmax = v;
+            }
+        }
+        else {
+            return ary_max_generic(ary, i, vmax);
+        }
+    }
+
+    return vmax;
+}
+
+static VALUE
+ary_max_opt_float(VALUE ary, long i, VALUE vmax)
+{
+    const long n = RARRAY_LEN(ary);
+    RUBY_ASSERT(i > 0 && i < n);
+    RUBY_ASSERT(RB_FLOAT_TYPE_P(vmax));
+
+    VALUE v;
+    for (; i < n; ++i) {
+        v = RARRAY_AREF(ary, i);
+
+        if (RB_FLOAT_TYPE_P(v)) {
+            if (rb_float_cmp(vmax, v) < 0) {
+                vmax = v;
+            }
+        }
+        else {
+            return ary_max_generic(ary, i, vmax);
+        }
+    }
+
+    return vmax;
+}
+
+static VALUE
+ary_max_opt_string(VALUE ary, long i, VALUE vmax)
+{
+    const long n = RARRAY_LEN(ary);
+    RUBY_ASSERT(i > 0 && i < n);
+    RUBY_ASSERT(STRING_P(vmax));
+
+    VALUE v;
+    for (; i < n; ++i) {
+        v = RARRAY_AREF(ary, i);
+
+        if (STRING_P(v)) {
+            if (rb_str_cmp(vmax, v) < 0) {
+                vmax = v;
+            }
+        }
+        else {
+            return ary_max_generic(ary, i, vmax);
+        }
+    }
+
+    return vmax;
+}
+
+/*
+ *  call-seq:
+ *    array.max -> element
+ *    array.max {|a, b| ... } -> element
+ *    array.max(n) -> new_array
+ *    array.max(n) {|a, b| ... } -> new_array
+ *
+ *  Returns one of the following:
  *
- *  Returns the object in _ary_ with the maximum value. The
- *  first form assumes all objects implement <code><=></code>;
- *  the second uses the block to return <em>a <=> b</em>.
+ *  - The maximum-valued element from +self+.
+ *  - A new \Array of maximum-valued elements selected from +self+.
  *
- *     ary = %w(albatross dog horse)
- *     ary.max                                   #=> "horse"
- *     ary.max {|a, b| a.length <=> b.length}    #=> "albatross"
+ *  When no block is given, each element in +self+ must respond to method <tt><=></tt>
+ *  with an \Integer.
  *
- *  If the +n+ argument is given, maximum +n+ elements are returned
- *  as an array.
+ *  With no argument and no block, returns the element in +self+
+ *  having the maximum value per method <tt><=></tt>:
+ *
+ *    [0, 1, 2].max # => 2
+ *
+ *  With an argument \Integer +n+ and no block, returns a new \Array with at most +n+ 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]
+ *
+ *  When a block is given, the block must return an \Integer.
+ *
+ *  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"
+ *
+ *  With an argument +n+ and a block, returns a new \Array with at most +n+ elements,
+ *  in descending order per the block:
+ *
+ *    ['0', '00', '000'].max(2) {|a, b| a.size <=> b.size } # => ["000", "00"]
  *
- *     ary = %w[albatross dog horse]
- *     ary.max(2)                                  #=> ["horse", "dog"]
- *     ary.max(2) {|a, b| a.length <=> b.length }  #=> ["albatross", "horse"]
  */
 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;
@@ -6022,52 +6067,167 @@ rb_ary_max(int argc, VALUE *argv, VALUE ary)
     if (rb_check_arity(argc, 0, 1) && !NIL_P(num = argv[0]))
        return rb_nmin_run(ary, num, 0, 1, 1);
 
+    const long n = RARRAY_LEN(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) {
-	       result = v;
-	   }
-	}
+        for (i = 0; i < RARRAY_LEN(ary); i++) {
+           v = RARRAY_AREF(ary, i);
+           if (UNDEF_P(result) || rb_cmpint(rb_yield_values(2, v, result), v, result) > 0) {
+               result = v;
+           }
+        }
     }
-    else {
-	for (i = 0; i < RARRAY_LEN(ary); i++) {
-	   v = RARRAY_AREF(ary, i);
-	   if (result == Qundef || OPTIMIZED_CMP(v, result, cmp_opt) > 0) {
-	       result = v;
-	   }
-	}
-    }
-    if (result == Qundef) return Qnil;
+    else if (n > 0) {
+        result = RARRAY_AREF(ary, 0);
+        if (n > 1) {
+            if (FIXNUM_P(result) && CMP_OPTIMIZABLE(INTEGER)) {
+                return ary_max_opt_fixnum(ary, 1, result);
+            }
+            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(FLOAT)) {
+                return ary_max_opt_float(ary, 1, result);
+            }
+            else {
+                return ary_max_generic(ary, 1, result);
+            }
+        }
+    }
+    if (UNDEF_P(result)) return Qnil;
     return result;
 }
 
+static VALUE
+ary_min_generic(VALUE ary, long i, VALUE vmin)
+{
+    RUBY_ASSERT(i > 0 && i < RARRAY_LEN(ary));
+
+    VALUE v;
+    for (; i < RARRAY_LEN(ary); ++i) {
+        v = RARRAY_AREF(ary, i);
+
+        if (rb_cmpint(rb_funcallv(vmin, id_cmp, 1, &v), vmin, v) > 0) {
+            vmin = v;
+        }
+    }
+
+    return vmin;
+}
+
+static VALUE
+ary_min_opt_fixnum(VALUE ary, long i, VALUE vmin)
+{
+    const long n = RARRAY_LEN(ary);
+    RUBY_ASSERT(i > 0 && i < n);
+    RUBY_ASSERT(FIXNUM_P(vmin));
+
+    VALUE a;
+    for (; i < n; ++i) {
+        a = RARRAY_AREF(ary, i);
+
+        if (FIXNUM_P(a)) {
+            if ((long)vmin > (long)a) {
+                vmin = a;
+            }
+        }
+        else {
+            return ary_min_generic(ary, i, vmin);
+        }
+    }
+
+    return vmin;
+}
+
+static VALUE
+ary_min_opt_float(VALUE ary, long i, VALUE vmin)
+{
+    const long n = RARRAY_LEN(ary);
+    RUBY_ASSERT(i > 0 && i < n);
+    RUBY_ASSERT(RB_FLOAT_TYPE_P(vmin));
+
+    VALUE a;
+    for (; i < n; ++i) {
+        a = RARRAY_AREF(ary, i);
+
+        if (RB_FLOAT_TYPE_P(a)) {
+            if (rb_float_cmp(vmin, a) > 0) {
+                vmin = a;
+            }
+        }
+        else {
+            return ary_min_generic(ary, i, vmin);
+        }
+    }
+
+    return vmin;
+}
+
+static VALUE
+ary_min_opt_string(VALUE ary, long i, VALUE vmin)
+{
+    const long n = RARRAY_LEN(ary);
+    RUBY_ASSERT(i > 0 && i < n);
+    RUBY_ASSERT(STRING_P(vmin));
+
+    VALUE a;
+    for (; i < n; ++i) {
+        a = RARRAY_AREF(ary, i);
+
+        if (STRING_P(a)) {
+            if (rb_str_cmp(vmin, a) > 0) {
+                vmin = a;
+            }
+        }
+        else {
+            return ary_min_generic(ary, i, vmin);
+        }
+    }
+
+    return vmin;
+}
+
 /*
  *  call-seq:
- *     ary.min                     -> obj
- *     ary.min {| a,b | block }    -> obj
- *     ary.min(n)                  -> array
- *     ary.min(n) {| a,b | block } -> array
+ *    array.min -> element
+ *    array.min { |a, b| ... } -> element
+ *    array.min(n) -> new_array
+ *    array.min(n) { |a, b| ... } -> new_array
+ *
+ *  Returns one of the following:
  *
- *  Returns the object in _ary_ with the minimum value. The
- *  first form assumes all objects implement <code><=></code>;
- *  the second uses the block to return <em>a <=> b</em>.
+ *  - The minimum-valued element from +self+.
+ *  - A new \Array of minimum-valued elements selected from +self+.
  *
- *     ary = %w(albatross dog horse)
- *     ary.min                                   #=> "albatross"
- *     ary.min {|a, b| a.length <=> b.length}    #=> "dog"
+ *  When no block is given, each element in +self+ must respond to method <tt><=></tt>
+ *  with an \Integer.
  *
- *  If the +n+ argument is given, minimum +n+ elements are returned
- *  as an array.
+ *  With no argument and no block, returns the element in +self+
+ *  having the minimum value per method <tt><=></tt>:
+ *
+ *    [0, 1, 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>:
+ *
+ *    [0, 1, 2, 3].min(3) # => [0, 1, 2]
+ *    [0, 1, 2, 3].min(6) # => [0, 1, 2, 3]
+ *
+ *  When a block is given, the block must return an Integer.
+ *
+ *  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"
+ *
+ *  With an argument +n+ and a block, returns a new \Array with at most +n+ elements,
+ *  in ascending order per the block:
+ *
+ *    ['0', '00', '000'].min(2) {|a, b| a.size <=> b.size } # => ["0", "00"]
  *
- *     ary = %w[albatross dog horse]
- *     ary.min(2)                                  #=> ["albatross", "dog"]
- *     ary.min(2) {|a, b| a.length <=> b.length }  #=> ["dog", "horse"]
  */
 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;
@@ -6075,36 +6235,58 @@ rb_ary_min(int argc, VALUE *argv, VALUE ary)
     if (rb_check_arity(argc, 0, 1) && !NIL_P(num = argv[0]))
        return rb_nmin_run(ary, num, 0, 0, 1);
 
+    const long n = RARRAY_LEN(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) {
-	       result = v;
-	   }
-	}
+        for (i = 0; i < RARRAY_LEN(ary); i++) {
+           v = RARRAY_AREF(ary, i);
+           if (UNDEF_P(result) || rb_cmpint(rb_yield_values(2, v, result), v, result) < 0) {
+               result = v;
+           }
+        }
     }
-    else {
-	for (i = 0; i < RARRAY_LEN(ary); i++) {
-	   v = RARRAY_AREF(ary, i);
-	   if (result == Qundef || OPTIMIZED_CMP(v, result, cmp_opt) < 0) {
-	       result = v;
-	   }
-	}
-    }
-    if (result == Qundef) return Qnil;
+    else if (n > 0) {
+        result = RARRAY_AREF(ary, 0);
+        if (n > 1) {
+            if (FIXNUM_P(result) && CMP_OPTIMIZABLE(INTEGER)) {
+                return ary_min_opt_fixnum(ary, 1, result);
+            }
+            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(FLOAT)) {
+                return ary_min_opt_float(ary, 1, result);
+            }
+            else {
+                return ary_min_generic(ary, 1, result);
+            }
+        }
+    }
+    if (UNDEF_P(result)) return Qnil;
     return result;
 }
 
 /*
  *  call-seq:
- *     ary.minmax                       -> [obj, obj]
- *     ary.minmax {| a,b | block }      -> [obj, obj]
+ *    array.minmax -> [min_val, max_val]
+ *    array.minmax {|a, b| ... } -> [min_val, max_val]
+ *
+ *  Returns a new 2-element \Array containing the minimum and maximum values
+ *  from +self+, either per method <tt><=></tt> or per a given block:.
+ *
+ *  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>:
+ *
+ *    [0, 1, 2].minmax # => [0, 2]
+ *
+ *  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:
  *
- *  Returns a two element array which contains the minimum and the
- *  maximum value in the array.
+ *    ['0', '00', '000'].minmax {|a, b| a.size <=> b.size } # => ["0", "000"]
  *
- *  Can be given an optional block to override the default comparison
- *  method <code>a <=> b</code>.
  */
 static VALUE
 rb_ary_minmax(VALUE ary)
@@ -6124,31 +6306,33 @@ push_value(st_data_t key, st_data_t val, st_data_t ary)
 
 /*
  *  call-seq:
- *     ary.uniq!                -> ary or nil
- *     ary.uniq! {|item| ...}   -> ary or nil
+ *    array.uniq! -> self or nil
+ *    array.uniq! {|element| ... } -> self or nil
  *
- *  Removes duplicate elements from +self+.
+ *  Removes duplicate elements from +self+, the first occurrence always being retained;
+ *  returns +self+ if any elements removed, +nil+ otherwise.
  *
- *  If a block is given, it will use the return value of the block for
- *  comparison.
+ *  With no block given, identifies and removes elements using method <tt>eql?</tt>
+ *  to compare.
  *
- *  It compares values using their #hash and #eql? methods for efficiency.
+ *  Returns +self+ if any elements removed:
  *
- *  +self+ is traversed in order, and the first occurrence is kept.
+ *    a = [0, 0, 1, 1, 2, 2]
+ *    a.uniq! # => [0, 1, 2]
  *
- *  Returns +nil+ if no changes are made (that is, no duplicates are found).
+ *  Returns +nil+ if no elements removed.
  *
- *     a = [ "a", "a", "b", "b", "c" ]
- *     a.uniq!   # => ["a", "b", "c"]
+ *  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.
  *
- *     b = [ "a", "b", "c" ]
- *     b.uniq!   # => nil
+ *  Returns +self+ if any elements removed:
  *
- *     c = [["student","sam"], ["student","george"], ["teacher","matz"]]
- *     c.uniq! {|s| s.first}   # => [["student", "sam"], ["teacher", "matz"]]
+ *    a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb']
+ *    a.uniq! {|element| element.size } # => ['a', 'aa', 'aaa']
  *
+ *  Returns +nil+ if no elements removed.
  */
-
 static VALUE
 rb_ary_uniq_bang(VALUE ary)
 {
@@ -6159,19 +6343,19 @@ rb_ary_uniq_bang(VALUE ary)
     if (RARRAY_LEN(ary) <= 1)
         return Qnil;
     if (rb_block_given_p())
-	hash = ary_make_hash_by(ary);
+        hash = ary_make_hash_by(ary);
     else
-	hash = ary_make_hash(ary);
+        hash = ary_make_hash(ary);
 
     hash_size = RHASH_SIZE(hash);
     if (RARRAY_LEN(ary) == hash_size) {
-	return Qnil;
+        return Qnil;
     }
     rb_ary_modify_check(ary);
     ARY_SET_LEN(ary, 0);
     if (ARY_SHARED_P(ary) && !ARY_EMBED_P(ary)) {
-	rb_ary_unshare(ary);
-	FL_SET_EMBED(ary);
+        rb_ary_unshare(ary);
+        FL_SET_EMBED(ary);
     }
     ary_resize_capa(ary, hash_size);
     rb_hash_foreach(hash, push_value, ary);
@@ -6182,22 +6366,24 @@ rb_ary_uniq_bang(VALUE ary)
 
 /*
  *  call-seq:
- *     ary.uniq                -> new_ary
- *     ary.uniq {|item| ...}   -> new_ary
- *
- *  Returns a new array by removing duplicate values in +self+.
+ *    array.uniq -> new_array
+ *    array.uniq {|element| ... } -> new_array
  *
- *  If a block is given, it will use the return value of the block for comparison.
+ *  Returns a new \Array containing those elements from +self+ that are not duplicates,
+ *  the first occurrence always being retained.
  *
- *  It compares values using their #hash and #eql? methods for efficiency.
+ *  With no block given, identifies and omits duplicates using method <tt>eql?</tt>
+ *  to compare:
  *
- *  +self+ is traversed in order, and the first occurrence is kept.
+ *    a = [0, 0, 1, 1, 2, 2]
+ *    a.uniq # => [0, 1, 2]
  *
- *     a = [ "a", "a", "b", "b", "c" ]
- *     a.uniq   # => ["a", "b", "c"]
+ *  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:
  *
- *     b = [["student","sam"], ["student","george"], ["teacher","matz"]]
- *     b.uniq {|s| s.first}   # => [["student", "sam"], ["teacher", "matz"]]
+ *    a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb']
+ *    a.uniq {|element| element.size } # => ["a", "aa", "aaa"]
  *
  */
 
@@ -6211,14 +6397,13 @@ rb_ary_uniq(VALUE ary)
         uniq = rb_ary_dup(ary);
     }
     else if (rb_block_given_p()) {
-	hash = ary_make_hash_by(ary);
-	uniq = rb_hash_values(hash);
+        hash = ary_make_hash_by(ary);
+        uniq = rb_hash_values(hash);
     }
     else {
-	hash = ary_make_hash(ary);
-	uniq = rb_hash_values(hash);
+        hash = ary_make_hash(ary);
+        uniq = rb_hash_values(hash);
     }
-    RBASIC_SET_CLASS(uniq, rb_obj_class(ary));
     if (hash) {
         ary_recycle_hash(hash);
     }
@@ -6228,14 +6413,11 @@ rb_ary_uniq(VALUE ary)
 
 /*
  *  call-seq:
- *     ary.compact!    -> ary  or  nil
+ *    array.compact! -> self or nil
  *
- *  Removes +nil+ elements from the array.
+ *  Removes all +nil+ elements from +self+.
  *
- *  Returns +nil+ if no changes were made, otherwise returns the array.
- *
- *     [ "a", nil, "b", nil, "c" ].compact! #=> [ "a", "b", "c" ]
- *     [ "a", "b", "c" ].compact!           #=> nil
+ *  Returns +self+ if any elements removed, otherwise +nil+.
  */
 
 static VALUE
@@ -6249,12 +6431,12 @@ rb_ary_compact_bang(VALUE ary)
     end = p + RARRAY_LEN(ary);
 
     while (t < end) {
-	if (NIL_P(*t)) t++;
-	else *p++ = *t++;
+        if (NIL_P(*t)) t++;
+        else *p++ = *t++;
     }
     n = p - RARRAY_CONST_PTR_TRANSIENT(ary);
     if (RARRAY_LEN(ary) == n) {
-	return Qnil;
+        return Qnil;
     }
     ary_resize_smaller(ary, n);
 
@@ -6263,12 +6445,12 @@ rb_ary_compact_bang(VALUE ary)
 
 /*
  *  call-seq:
- *     ary.compact     -> new_ary
+ *    array.compact -> new_array
  *
- *  Returns a copy of +self+ with all +nil+ elements removed.
+ *  Returns a new \Array containing all non-+nil+ elements from +self+:
  *
- *     [ "a", nil, "b", nil, "c", nil ].compact
- *                       #=> [ "a", "b", "c" ]
+ *    a = [nil, 0, nil, 1, nil, 2, nil]
+ *    a.compact # => [0, 1, 2]
  */
 
 static VALUE
@@ -6281,23 +6463,29 @@ rb_ary_compact(VALUE ary)
 
 /*
  *  call-seq:
- *     ary.count                   -> int
- *     ary.count(obj)              -> int
- *     ary.count {|item| block}    -> int
+ *    array.count -> an_integer
+ *    array.count(obj) -> an_integer
+ *    array.count {|element| ... } -> an_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
  *
- *  Returns the number of elements.
+ *  With argument +obj+, returns the count of elements <tt>==</tt> to +obj+:
  *
- *  If an argument is given, counts the number of elements which equal +obj+
- *  using <code>==</code>.
+ *    [0, 1, 2, 0.0].count(0) # => 2
+ *    [0, 1, 2].count(3) # => 0
  *
- *  If a block is given, counts the number of elements for which the block
- *  returns a true value.
+ *  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:
  *
- *     ary = [1, 2, 4, 2]
- *     ary.count                  #=> 4
- *     ary.count(2)               #=> 2
- *     ary.count {|x| x%2 == 0}   #=> 3
+ *    [0, 1, 2, 3].count {|element| element > 1} # => 2
  *
+ *  With argument +obj+ and a block given, issues a warning, ignores the block,
+ *  and returns the count of elements <tt>==</tt> to +obj+.
  */
 
 static VALUE
@@ -6306,25 +6494,25 @@ rb_ary_count(int argc, VALUE *argv, VALUE ary)
     long i, n = 0;
 
     if (rb_check_arity(argc, 0, 1) == 0) {
-	VALUE v;
+        VALUE v;
 
-	if (!rb_block_given_p())
-	    return LONG2NUM(RARRAY_LEN(ary));
+        if (!rb_block_given_p())
+            return LONG2NUM(RARRAY_LEN(ary));
 
-	for (i = 0; i < RARRAY_LEN(ary); i++) {
-	    v = RARRAY_AREF(ary, i);
-	    if (RTEST(rb_yield(v))) n++;
-	}
+        for (i = 0; i < RARRAY_LEN(ary); i++) {
+            v = RARRAY_AREF(ary, i);
+            if (RTEST(rb_yield(v))) n++;
+        }
     }
     else {
         VALUE obj = argv[0];
 
-	if (rb_block_given_p()) {
-	    rb_warn("given block not used");
-	}
-	for (i = 0; i < RARRAY_LEN(ary); i++) {
-	    if (rb_equal(RARRAY_AREF(ary, i), obj)) n++;
-	}
+        if (rb_block_given_p()) {
+            rb_warn("given block not used");
+        }
+        for (i = 0; i < RARRAY_LEN(ary); i++) {
+            if (rb_equal(RARRAY_AREF(ary, i), obj)) n++;
+        }
     }
 
     return LONG2NUM(n);
@@ -6335,7 +6523,7 @@ flatten(VALUE ary, int level)
 {
     long i;
     VALUE stack, result, tmp = 0, elt, vmemo;
-    st_table *memo;
+    st_table *memo = 0;
     st_data_t id;
 
     for (i = 0; i < RARRAY_LEN(ary); i++) {
@@ -6347,8 +6535,6 @@ flatten(VALUE ary, int level)
     }
     if (i == RARRAY_LEN(ary)) {
         return ary;
-    } else if (tmp == ary) {
-        rb_raise(rb_eArgError, "tried to flatten recursive array");
     }
 
     result = ary_new(0, RARRAY_LEN(ary));
@@ -6359,79 +6545,100 @@ flatten(VALUE ary, int level)
     rb_ary_push(stack, ary);
     rb_ary_push(stack, LONG2NUM(i + 1));
 
-    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);
+    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);
+    }
 
     ary = tmp;
     i = 0;
 
     while (1) {
-	while (i < RARRAY_LEN(ary)) {
-	    elt = RARRAY_AREF(ary, i++);
-	    if (level >= 0 && RARRAY_LEN(stack) / 2 >= level) {
-		rb_ary_push(result, elt);
-		continue;
-	    }
-	    tmp = rb_check_array_type(elt);
-	    if (RBASIC(result)->klass) {
-                RB_GC_GUARD(vmemo);
-                st_clear(memo);
-		rb_raise(rb_eRuntimeError, "flatten reentered");
-	    }
-	    if (NIL_P(tmp)) {
-		rb_ary_push(result, elt);
-	    }
-	    else {
-		id = (st_data_t)tmp;
-		if (st_is_member(memo, id)) {
+        while (i < RARRAY_LEN(ary)) {
+            elt = RARRAY_AREF(ary, i++);
+            if (level >= 0 && RARRAY_LEN(stack) / 2 >= level) {
+                rb_ary_push(result, elt);
+                continue;
+            }
+            tmp = rb_check_array_type(elt);
+            if (RBASIC(result)->klass) {
+                if (memo) {
+                    RB_GC_GUARD(vmemo);
                     st_clear(memo);
-		    rb_raise(rb_eArgError, "tried to flatten recursive array");
-		}
-		st_insert(memo, id, (st_data_t)Qtrue);
-		rb_ary_push(stack, ary);
-		rb_ary_push(stack, LONG2NUM(i));
-		ary = tmp;
-		i = 0;
-	    }
-	}
-	if (RARRAY_LEN(stack) == 0) {
-	    break;
-	}
-	id = (st_data_t)ary;
-	st_delete(memo, &id, 0);
-	tmp = rb_ary_pop(stack);
-	i = NUM2LONG(tmp);
-	ary = rb_ary_pop(stack);
-    }
-
-    st_clear(memo);
-
-    RBASIC_SET_CLASS(result, rb_obj_class(ary));
+                }
+                rb_raise(rb_eRuntimeError, "flatten reentered");
+            }
+            if (NIL_P(tmp)) {
+                rb_ary_push(result, elt);
+            }
+            else {
+                if (memo) {
+                    id = (st_data_t)tmp;
+                    if (st_is_member(memo, id)) {
+                        st_clear(memo);
+                        rb_raise(rb_eArgError, "tried to flatten recursive array");
+                    }
+                    st_insert(memo, id, (st_data_t)Qtrue);
+                }
+                rb_ary_push(stack, ary);
+                rb_ary_push(stack, LONG2NUM(i));
+                ary = tmp;
+                i = 0;
+            }
+        }
+        if (RARRAY_LEN(stack) == 0) {
+            break;
+        }
+        if (memo) {
+            id = (st_data_t)ary;
+            st_delete(memo, &id, 0);
+        }
+        tmp = rb_ary_pop(stack);
+        i = NUM2LONG(tmp);
+        ary = rb_ary_pop(stack);
+    }
+
+    if (memo) {
+        st_clear(memo);
+    }
+
+    RBASIC_SET_CLASS(result, rb_cArray);
     return result;
 }
 
 /*
  *  call-seq:
- *     ary.flatten!        -> ary or nil
- *     ary.flatten!(level) -> ary or nil
+ *    array.flatten! -> self or nil
+ *    array.flatten!(level) -> self or nil
  *
- *  Flattens +self+ in place.
+ *  Replaces each nested \Array in +self+ with the elements from that \Array;
+ *  returns +self+ if any changes, +nil+ otherwise.
  *
- *  Returns +nil+ if no modifications were made (i.e., the array contains no
- *  subarrays.)
+ *  With non-negative \Integer argument +level+, flattens recursively through +level+ levels:
  *
- *  The optional +level+ argument determines the level of recursion to 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
+ *
+ *  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! # => 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 = [ 1, 2, [3, [4, 5] ] ]
- *     a.flatten!   #=> [1, 2, 3, 4, 5]
- *     a.flatten!   #=> nil
- *     a            #=> [1, 2, 3, 4, 5]
- *     a = [ 1, 2, [3, [4, 5] ] ]
- *     a.flatten!(1) #=> [1, 2, 3, [4, 5]]
  */
 
 static VALUE
@@ -6447,7 +6654,7 @@ rb_ary_flatten_bang(int argc, VALUE *argv, VALUE ary)
 
     result = flatten(ary, level);
     if (result == ary) {
-	return Qnil;
+        return Qnil;
     }
     if (!(mod = ARY_EMBED_P(result))) rb_obj_freeze(result);
     rb_ary_replace(ary, result);
@@ -6458,24 +6665,35 @@ rb_ary_flatten_bang(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *     ary.flatten -> new_ary
- *     ary.flatten(level) -> new_ary
- *
- *  Returns a new array that is a one-dimensional flattening of +self+
- *  (recursively).
- *
- *  That is, for every element that is an array, extract its elements into
- *  the new array.
+ *    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]
  *
- *  The optional +level+ argument determines the level of recursion to
- *  flatten.
- *
- *     s = [ 1, 2, 3 ]           #=> [1, 2, 3]
- *     t = [ 4, 5, 6, [7, 8] ]   #=> [4, 5, 6, [7, 8]]
- *     a = [ s, t, 9, 10 ]       #=> [[1, 2, 3], [4, 5, 6, [7, 8]], 9, 10]
- *     a.flatten                 #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
- *     a = [ 1, 2, [3, [4, 5] ] ]
- *     a.flatten(1)              #=> [1, 2, 3, [4, 5]]
  */
 
 static VALUE
@@ -6507,16 +6725,16 @@ 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) {
-	    long j = RAND_UPTO(i);
-	    VALUE tmp;
+        while (i) {
+            long j = RAND_UPTO(i);
+            VALUE tmp;
             if (len != RARRAY_LEN(ary) || ptr != RARRAY_CONST_PTR_TRANSIENT(ary)) {
                 rb_raise(rb_eRuntimeError, "modified during shuffle");
-	    }
-	    tmp = ptr[--i];
-	    ptr[i] = ptr[j];
-	    ptr[j] = tmp;
-	}
+            }
+            tmp = ptr[--i];
+            ptr[i] = ptr[j];
+            ptr[j] = tmp;
+        }
     }); /* WB: no new reference */
     return ary;
 }
@@ -6530,7 +6748,7 @@ rb_ary_shuffle(rb_execution_context_t *ec, VALUE ary, VALUE randgen)
 }
 
 static VALUE
-rb_ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VALUE to_array)
+ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VALUE to_array)
 {
     VALUE result;
     long n, len, i, j, k, idx[10];
@@ -6539,120 +6757,120 @@ rb_ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VA
 
     len = RARRAY_LEN(ary);
     if (!to_array) {
-	if (len < 2)
-	    i = 0;
-	else
-	    i = RAND_UPTO(len);
+        if (len < 2)
+            i = 0;
+        else
+            i = RAND_UPTO(len);
 
-	return rb_ary_elt(ary, i);
+        return rb_ary_elt(ary, i);
     }
     n = NUM2LONG(nv);
     if (n < 0) rb_raise(rb_eArgError, "negative sample number");
     if (n > len) n = len;
     if (n <= numberof(idx)) {
-	for (i = 0; i < n; ++i) {
-	    rnds[i] = RAND_UPTO(len - i);
-	}
+        for (i = 0; i < n; ++i) {
+            rnds[i] = RAND_UPTO(len - i);
+        }
     }
     k = len;
     len = RARRAY_LEN(ary);
     if (len < k && n <= numberof(idx)) {
-	for (i = 0; i < n; ++i) {
-	    if (rnds[i] >= len) return rb_ary_new_capa(0);
-	}
+        for (i = 0; i < n; ++i) {
+            if (rnds[i] >= len) return rb_ary_new_capa(0);
+        }
     }
     if (n > len) n = len;
     switch (n) {
       case 0:
-	return rb_ary_new_capa(0);
+        return rb_ary_new_capa(0);
       case 1:
-	i = rnds[0];
-	return rb_ary_new_from_values(1, &RARRAY_AREF(ary, i));
+        i = rnds[0];
+        return rb_ary_new_from_args(1, RARRAY_AREF(ary, i));
       case 2:
-	i = rnds[0];
-	j = rnds[1];
-	if (j >= i) j++;
-	return rb_ary_new_from_args(2, RARRAY_AREF(ary, i), RARRAY_AREF(ary, j));
+        i = rnds[0];
+        j = rnds[1];
+        if (j >= i) j++;
+        return rb_ary_new_from_args(2, RARRAY_AREF(ary, i), RARRAY_AREF(ary, j));
       case 3:
-	i = rnds[0];
-	j = rnds[1];
-	k = rnds[2];
-	{
-	    long l = j, g = i;
-	    if (j >= i) l = i, g = ++j;
-	    if (k >= l && (++k >= g)) ++k;
-	}
-	return rb_ary_new_from_args(3, RARRAY_AREF(ary, i), RARRAY_AREF(ary, j), RARRAY_AREF(ary, k));
+        i = rnds[0];
+        j = rnds[1];
+        k = rnds[2];
+        {
+            long l = j, g = i;
+            if (j >= i) l = i, g = ++j;
+            if (k >= l && (++k >= g)) ++k;
+        }
+        return rb_ary_new_from_args(3, RARRAY_AREF(ary, i), RARRAY_AREF(ary, j), RARRAY_AREF(ary, k));
     }
     memo_threshold =
-	len < 2560 ? len / 128 :
-	len < 5120 ? len / 64 :
-	len < 10240 ? len / 32 :
-	len / 16;
+        len < 2560 ? len / 128 :
+        len < 5120 ? len / 64 :
+        len < 10240 ? len / 32 :
+        len / 16;
     if (n <= numberof(idx)) {
-	long sorted[numberof(idx)];
-	sorted[0] = idx[0] = rnds[0];
-	for (i=1; i<n; i++) {
-	    k = rnds[i];
-	    for (j = 0; j < i; ++j) {
-		if (k < sorted[j]) break;
-		++k;
-	    }
-	    memmove(&sorted[j+1], &sorted[j], sizeof(sorted[0])*(i-j));
-	    sorted[j] = idx[i] = k;
-	}
-	result = rb_ary_new_capa(n);
+        long sorted[numberof(idx)];
+        sorted[0] = idx[0] = rnds[0];
+        for (i=1; i<n; i++) {
+            k = rnds[i];
+            for (j = 0; j < i; ++j) {
+                if (k < sorted[j]) break;
+                ++k;
+            }
+            memmove(&sorted[j+1], &sorted[j], sizeof(sorted[0])*(i-j));
+            sorted[j] = idx[i] = k;
+        }
+        result = rb_ary_new_capa(n);
         RARRAY_PTR_USE_TRANSIENT(result, ptr_result, {
-	    for (i=0; i<n; i++) {
-		ptr_result[i] = RARRAY_AREF(ary, idx[i]);
-	    }
-	});
+            for (i=0; i<n; i++) {
+                ptr_result[i] = RARRAY_AREF(ary, idx[i]);
+            }
+        });
     }
     else if (n <= memo_threshold / 2) {
-	long max_idx = 0;
+        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);
-	st_table *memo = st_init_numtable_with_size(n);
-	DATA_PTR(vmemo) = memo;
-	result = rb_ary_new_capa(n);
-	RARRAY_PTR_USE(result, ptr_result, {
-	    for (i=0; i<n; i++) {
-		long r = RAND_UPTO(len-i) + i;
-		ptr_result[i] = r;
-		if (r > max_idx) max_idx = r;
-	    }
-	    len = RARRAY_LEN(ary);
-	    if (len <= max_idx) n = 0;
-	    else if (n > len) n = len;
+        VALUE vmemo = Data_Wrap_Struct(0, 0, st_free_table, 0);
+        st_table *memo = st_init_numtable_with_size(n);
+        DATA_PTR(vmemo) = memo;
+        result = rb_ary_new_capa(n);
+        RARRAY_PTR_USE(result, ptr_result, {
+            for (i=0; i<n; i++) {
+                long r = RAND_UPTO(len-i) + i;
+                ptr_result[i] = r;
+                if (r > max_idx) max_idx = r;
+            }
+            len = RARRAY_LEN(ary);
+            if (len <= max_idx) n = 0;
+            else if (n > len) n = len;
             RARRAY_PTR_USE_TRANSIENT(ary, ptr_ary, {
-		for (i=0; i<n; i++) {
-		    long j2 = j = ptr_result[i];
-		    long i2 = i;
-		    st_data_t value;
-		    if (st_lookup(memo, (st_data_t)i, &value)) i2 = (long)value;
-		    if (st_lookup(memo, (st_data_t)j, &value)) j2 = (long)value;
-		    st_insert(memo, (st_data_t)j, (st_data_t)i2);
-		    ptr_result[i] = ptr_ary[j2];
-		}
-	    });
-	});
-	DATA_PTR(vmemo) = 0;
-	st_free_table(memo);
+                for (i=0; i<n; i++) {
+                    long j2 = j = ptr_result[i];
+                    long i2 = i;
+                    st_data_t value;
+                    if (st_lookup(memo, (st_data_t)i, &value)) i2 = (long)value;
+                    if (st_lookup(memo, (st_data_t)j, &value)) j2 = (long)value;
+                    st_insert(memo, (st_data_t)j, (st_data_t)i2);
+                    ptr_result[i] = ptr_ary[j2];
+                }
+            });
+        });
+        DATA_PTR(vmemo) = 0;
+        st_free_table(memo);
     }
     else {
-	result = rb_ary_dup(ary);
-	RBASIC_CLEAR_CLASS(result);
-	RB_GC_GUARD(ary);
-	RARRAY_PTR_USE(result, ptr_result, {
-	    for (i=0; i<n; i++) {
-		j = RAND_UPTO(len-i) + i;
-		nv = ptr_result[j];
-		ptr_result[j] = ptr_result[i];
-		ptr_result[i] = nv;
-	    }
-	});
-	RBASIC_SET_CLASS_RAW(result, rb_cArray);
+        result = rb_ary_dup(ary);
+        RBASIC_CLEAR_CLASS(result);
+        RB_GC_GUARD(ary);
+        RARRAY_PTR_USE(result, ptr_result, {
+            for (i=0; i<n; i++) {
+                j = RAND_UPTO(len-i) + i;
+                nv = ptr_result[j];
+                ptr_result[j] = ptr_result[i];
+                ptr_result[i] = nv;
+            }
+        });
+        RBASIC_SET_CLASS_RAW(result, rb_cArray);
     }
     ARY_SET_LEN(result, n);
 
@@ -6660,15 +6878,21 @@ rb_ary_sample(rb_execution_context_t *ec, VALUE ary, VALUE randgen, VALUE nv, VA
 }
 
 static VALUE
+ary_sample0(rb_execution_context_t *ec, VALUE ary)
+{
+    return ary_sample(ec, ary, rb_cRandom, Qfalse, Qfalse);
+}
+
+static VALUE
 rb_ary_cycle_size(VALUE self, VALUE args, VALUE eobj)
 {
     long mul;
     VALUE n = Qnil;
     if (args && (RARRAY_LEN(args) > 0)) {
-	n = RARRAY_AREF(args, 0);
+        n = RARRAY_AREF(args, 0);
     }
     if (RARRAY_LEN(self) == 0) return INT2FIX(0);
-    if (n == Qnil) return DBL2NUM(HUGE_VAL);
+    if (NIL_P(n)) return DBL2NUM(HUGE_VAL);
     mul = NUM2LONG(n);
     if (mul <= 0) return INT2FIX(0);
     n = LONG2FIX(mul);
@@ -6677,24 +6901,37 @@ rb_ary_cycle_size(VALUE self, VALUE args, VALUE eobj)
 
 /*
  *  call-seq:
- *     ary.cycle(n=nil) {|obj| block}    -> nil
- *     ary.cycle(n=nil)                  -> Enumerator
+ *    array.cycle {|element| ... } -> nil
+ *    array.cycle(count) {|element| ... } -> nil
+ *    array.cycle -> new_enumerator
+ *    array.cycle(count) -> new_enumerator
+ *
+ *  When called with positive \Integer argument +count+ and a block,
+ *  calls the block with each element, then does so again,
+ *  until it has done so +count+ times; returns +nil+:
  *
- *  Calls the given block for each element +n+ times or forever if +nil+ is
- *  given.
+ *    output = []
+ *    [0, 1].cycle(2) {|element| output.push(element) } # => nil
+ *    output # => [0, 1, 0, 1]
  *
- *  Does nothing if a non-positive number is given or the array is empty.
+ *  If +count+ is zero or negative, does not call the block:
  *
- *  Returns +nil+ if the loop has finished without getting interrupted.
+ *    [0, 1].cycle(0) {|element| fail 'Cannot happen' } # => nil
+ *    [0, 1].cycle(-1) {|element| fail 'Cannot happen' } # => nil
  *
- *  If no block is given, an Enumerator is returned instead.
+ *  When a block is given, and argument is omitted or +nil+, cycles forever:
  *
- *     a = ["a", "b", "c"]
- *     a.cycle {|x| puts x}       # print, a, b, c, a, b, c,.. forever.
- *     a.cycle(2) {|x| puts x}    # print, a, b, c, a, b, c.
+ *    # 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]
  *
  */
-
 static VALUE
 rb_ary_cycle(int argc, VALUE *argv, VALUE ary)
 {
@@ -6719,9 +6956,6 @@ rb_ary_cycle(int argc, VALUE *argv, VALUE ary)
     return Qnil;
 }
 
-#define tmpary(n) rb_ary_tmp_new(n)
-#define tmpary_discard(a) (ary_discard(a), RBASIC_SET_CLASS_RAW(a, rb_cArray))
-
 /*
  * Build a ruby array of the corresponding values and yield it to the
  * associated block.
@@ -6757,52 +6991,52 @@ permute0(const long n, const long r, long *const p, char *const used, const VALU
     long i = 0, index = 0;
 
     for (;;) {
-	const char *const unused = memchr(&used[i], 0, n-i);
-	if (!unused) {
-	    if (!index) break;
-	    i = p[--index];                /* pop index */
-	    used[i++] = 0;                 /* index unused */
-	}
-	else {
-	    i = unused - used;
-	    p[index] = i;
-	    used[i] = 1;                   /* mark index used */
-	    ++index;
-	    if (index < r-1) {             /* if not done yet */
-		p[index] = i = 0;
-		continue;
-	    }
-	    for (i = 0; i < n; ++i) {
-		if (used[i]) continue;
-		p[index] = i;
-		if (!yield_indexed_values(values, r, p)) {
-		    rb_raise(rb_eRuntimeError, "permute reentered");
-		}
-	    }
-	    i = p[--index];                /* pop index */
-	    used[i] = 0;                   /* index unused */
-	    p[index] = ++i;
-	}
+        const char *const unused = memchr(&used[i], 0, n-i);
+        if (!unused) {
+            if (!index) break;
+            i = p[--index];                /* pop index */
+            used[i++] = 0;                 /* index unused */
+        }
+        else {
+            i = unused - used;
+            p[index] = i;
+            used[i] = 1;                   /* mark index used */
+            ++index;
+            if (index < r-1) {             /* if not done yet */
+                p[index] = i = 0;
+                continue;
+            }
+            for (i = 0; i < n; ++i) {
+                if (used[i]) continue;
+                p[index] = i;
+                if (!yield_indexed_values(values, r, p)) {
+                    rb_raise(rb_eRuntimeError, "permute reentered");
+                }
+            }
+            i = p[--index];                /* pop index */
+            used[i] = 0;                   /* index unused */
+            p[index] = ++i;
+        }
     }
 }
 
 /*
  * Returns the product of from, from-1, ..., from - how_many + 1.
- * http://en.wikipedia.org/wiki/Pochhammer_symbol
+ * https://en.wikipedia.org/wiki/Pochhammer_symbol
  */
 static VALUE
 descending_factorial(long from, long how_many)
 {
     VALUE cnt;
     if (how_many > 0) {
-	cnt = LONG2FIX(from);
-	while (--how_many > 0) {
-	    long v = --from;
-	    cnt = rb_int_mul(cnt, LONG2FIX(v));
-	}
+        cnt = LONG2FIX(from);
+        while (--how_many > 0) {
+            long v = --from;
+            cnt = rb_int_mul(cnt, LONG2FIX(v));
+        }
     }
     else {
-	cnt = LONG2FIX(how_many == 0);
+        cnt = LONG2FIX(how_many == 0);
     }
     return cnt;
 }
@@ -6813,18 +7047,18 @@ binomial_coefficient(long comb, long size)
     VALUE r;
     long i;
     if (comb > size-comb) {
-	comb = size-comb;
+        comb = size-comb;
     }
     if (comb < 0) {
-	return LONG2FIX(0);
+        return LONG2FIX(0);
     }
     else if (comb == 0) {
-	return LONG2FIX(1);
+        return LONG2FIX(1);
     }
     r = LONG2FIX(size);
     for (i = 1; i < comb; ++i) {
-	r = rb_int_mul(r, LONG2FIX(size - i));
-	r = rb_int_idiv(r, LONG2FIX(i + 1));
+        r = rb_int_mul(r, LONG2FIX(size - i));
+        r = rb_int_idiv(r, LONG2FIX(i + 1));
     }
     return r;
 }
@@ -6840,30 +7074,82 @@ rb_ary_permutation_size(VALUE ary, VALUE args, VALUE eobj)
 
 /*
  *  call-seq:
- *     ary.permutation {|p| block}            -> ary
- *     ary.permutation                        -> Enumerator
- *     ary.permutation(n) {|p| block}         -> ary
- *     ary.permutation(n)                     -> Enumerator
+ *    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 invoked with a block, yield all permutations of length +n+ of the
- * elements of the array, then return the array itself.
+ *  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+.
  *
- * If +n+ is not specified, yield all permutations of all elements.
+ *  Example:
  *
- * The implementation makes no guarantees about the order in which the
- * permutations are yielded.
+ *    a = [0, 1, 2]
+ *    a.permutation(2) {|permutation| p permutation }
+ *
+ *  Output:
+ *
+ *    [0, 1]
+ *    [0, 2]
+ *    [1, 0]
+ *    [1, 2]
+ *    [2, 0]
+ *    [2, 1]
+ *
+ *  Another example:
+ *
+ *    a = [0, 1, 2]
+ *    a.permutation(3) {|permutation| p permutation }
+ *
+ *  Output:
+ *
+ *    [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:
+ *
+ *    a = [0, 1, 2]
+ *    a.permutation(0) {|permutation| p permutation }
+ *
+ *  Output:
  *
- * If no block is given, an Enumerator is returned instead.
+ *    []
  *
- * Examples:
+ *  When +n+ 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)>
  *
- *   a = [1, 2, 3]
- *   a.permutation.to_a    #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
- *   a.permutation(1).to_a #=> [[1],[2],[3]]
- *   a.permutation(2).to_a #=> [[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]]
- *   a.permutation(3).to_a #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
- *   a.permutation(0).to_a #=> [[]] # one permutation of length 0
- *   a.permutation(4).to_a #=> []   # no permutations of length 4
  */
 
 static VALUE
@@ -6878,28 +7164,28 @@ rb_ary_permutation(int argc, VALUE *argv, VALUE ary)
         r = NUM2LONG(argv[0]);            /* Permutation size from argument */
 
     if (r < 0 || n < r) {
-	/* no permutations: yield nothing */
+        /* no permutations: yield nothing */
     }
     else if (r == 0) { /* exactly one permutation: the zero-length array */
-	rb_yield(rb_ary_new2(0));
+        rb_yield(rb_ary_new2(0));
     }
     else if (r == 1) { /* this is a special, easy case */
-	for (i = 0; i < RARRAY_LEN(ary); i++) {
-	    rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
-	}
+        for (i = 0; i < RARRAY_LEN(ary); i++) {
+            rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
+        }
     }
     else {             /* this is the general case */
-	volatile VALUE t0;
-	long *p = ALLOCV_N(long, t0, r+roomof(n, sizeof(long)));
-	char *used = (char*)(p + r);
-	VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
-	RBASIC_CLEAR_CLASS(ary0);
+        volatile VALUE t0;
+        long *p = ALLOCV_N(long, t0, r+roomof(n, sizeof(long)));
+        char *used = (char*)(p + r);
+        VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
+        RBASIC_CLEAR_CLASS(ary0);
 
-	MEMZERO(used, char, n); /* initialize array */
+        MEMZERO(used, char, n); /* initialize array */
 
-	permute0(n, r, p, used, ary0); /* compute and yield permutations */
-	ALLOCV_END(t0);
-	RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
+        permute0(n, r, p, used, ary0); /* compute and yield permutations */
+        ALLOCV_END(t0);
+        RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
     }
     return ary;
 }
@@ -6912,16 +7198,16 @@ combinate0(const long len, const long n, long *const stack, const VALUE values)
     MEMZERO(stack+1, long, n);
     stack[0] = -1;
     for (;;) {
-	for (lev++; lev < n; lev++) {
-	    stack[lev+1] = stack[lev]+1;
-	}
-	if (!yield_indexed_values(values, n, stack+1)) {
-	    rb_raise(rb_eRuntimeError, "combination reentered");
-	}
-	do {
-	    if (lev == 0) return;
-	    stack[lev--]++;
-	} while (stack[lev+1]+n == len+lev+1);
+        for (lev++; lev < n; lev++) {
+            stack[lev+1] = stack[lev]+1;
+        }
+        if (!yield_indexed_values(values, n, stack+1)) {
+            rb_raise(rb_eRuntimeError, "combination reentered");
+        }
+        do {
+            if (lev == 0) return;
+            stack[lev--]++;
+        } while (stack[lev+1]+n == len+lev+1);
     }
 }
 
@@ -6936,26 +7222,55 @@ rb_ary_combination_size(VALUE ary, VALUE args, VALUE eobj)
 
 /*
  *  call-seq:
- *     ary.combination(n) {|c| block}      -> ary
- *     ary.combination(n)                  -> Enumerator
+ *    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.
+ *
+ *  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+.
  *
- * When invoked with a block, yields all combinations of length +n+ of elements
- * from the array and then returns the array itself.
+ *  Example:
+ *
+ *    a = [0, 1, 2]
+ *    a.combination(2) {|combination| p combination }
  *
- * The implementation makes no guarantees about the order in which the
- * combinations are yielded.
+ *  Output:
+ *
+ *    [0, 1]
+ *    [0, 2]
+ *    [1, 2]
+ *
+ *  Another example:
+ *
+ *    a = [0, 1, 2]
+ *    a.combination(3) {|combination| p combination }
+ *
+ *  Output:
  *
- * If no block is given, an Enumerator is returned instead.
+ *    [0, 1, 2]
  *
- * Examples:
+ *  When +n+ is zero, calls the block once with a new empty \Array:
  *
- *     a = [1, 2, 3, 4]
- *     a.combination(1).to_a  #=> [[1],[2],[3],[4]]
- *     a.combination(2).to_a  #=> [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]
- *     a.combination(3).to_a  #=> [[1,2,3],[1,2,4],[1,3,4],[2,3,4]]
- *     a.combination(4).to_a  #=> [[1,2,3,4]]
- *     a.combination(0).to_a  #=> [[]] # one combination of length 0
- *     a.combination(5).to_a  #=> []   # no combinations of length 5
+ *    a = [0, 1, 2]
+ *    a1 = a.combination(0) {|combination| p combination }
+ *
+ *  Output:
+ *
+ *    []
+ *
+ *  When +n+ is out of range (negative or larger than <tt>self.size</tt>),
+ *  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 = [0, 1, 2]
+ *    a.combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>
  *
  */
 
@@ -6968,25 +7283,25 @@ rb_ary_combination(VALUE ary, VALUE num)
     RETURN_SIZED_ENUMERATOR(ary, 1, &num, rb_ary_combination_size);
     len = RARRAY_LEN(ary);
     if (n < 0 || len < n) {
-	/* yield nothing */
+        /* yield nothing */
     }
     else if (n == 0) {
-	rb_yield(rb_ary_new2(0));
+        rb_yield(rb_ary_new2(0));
     }
     else if (n == 1) {
-	for (i = 0; i < RARRAY_LEN(ary); i++) {
-	    rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
-	}
+        for (i = 0; i < RARRAY_LEN(ary); i++) {
+            rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
+        }
     }
     else {
-	VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
-	volatile VALUE t0;
-	long *stack = ALLOCV_N(long, t0, n+1);
+        VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
+        volatile VALUE t0;
+        long *stack = ALLOCV_N(long, t0, n+1);
 
-	RBASIC_CLEAR_CLASS(ary0);
-	combinate0(len, n, stack, ary0);
-	ALLOCV_END(t0);
-	RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
+        RBASIC_CLEAR_CLASS(ary0);
+        combinate0(len, n, stack, ary0);
+        ALLOCV_END(t0);
+        RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
     }
     return ary;
 }
@@ -7010,19 +7325,19 @@ rpermute0(const long n, const long r, long *const p, const VALUE values)
 
     p[index] = i;
     for (;;) {
-	if (++index < r-1) {
-	    p[index] = i = 0;
-	    continue;
-	}
-	for (i = 0; i < n; ++i) {
-	    p[index] = i;
-	    if (!yield_indexed_values(values, r, p)) {
-		rb_raise(rb_eRuntimeError, "repeated permute reentered");
-	    }
-	}
-	do {
-	    if (index <= 0) return;
-	} while ((i = ++p[--index]) >= n);
+        if (++index < r-1) {
+            p[index] = i = 0;
+            continue;
+        }
+        for (i = 0; i < n; ++i) {
+            p[index] = i;
+            if (!yield_indexed_values(values, r, p)) {
+                rb_raise(rb_eRuntimeError, "repeated permute reentered");
+            }
+        }
+        do {
+            if (index <= 0) return;
+        } while ((i = ++p[--index]) >= n);
     }
 }
 
@@ -7033,37 +7348,79 @@ rb_ary_repeated_permutation_size(VALUE ary, VALUE args, VALUE eobj)
     long k = NUM2LONG(RARRAY_AREF(args, 0));
 
     if (k < 0) {
-	return LONG2FIX(0);
+        return LONG2FIX(0);
     }
     if (n <= 0) {
-	return LONG2FIX(!k);
+        return LONG2FIX(!k);
     }
     return rb_int_positive_pow(n, (unsigned long)k);
 }
 
 /*
  *  call-seq:
- *     ary.repeated_permutation(n) {|p| block}   -> ary
- *     ary.repeated_permutation(n)               -> Enumerator
+ *    array.repeated_permutation(n) {|permutation| ... } -> self
+ *    array.repeated_permutation(n) -> new_enumerator
+ *
+ *  Calls the block with each repeated permutation of length +n+ 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 }
  *
- * When invoked with a block, yield all repeated permutations of length +n+ of
- * the elements of the array, then return the array itself.
+ *  Output:
+ *
+ *    [0]
+ *    [1]
+ *    [2]
+ *
+ *  +n+ = 2:
  *
- * The implementation makes no guarantees about the order in which the repeated
- * permutations are yielded.
+ *    a.repeated_permutation(2) {|permutation| p permutation }
+ *
+ *  Output:
  *
- * If no block is given, an Enumerator is returned instead.
+ *    [0, 0]
+ *    [0, 1]
+ *    [0, 2]
+ *    [1, 0]
+ *    [1, 1]
+ *    [1, 2]
+ *    [2, 0]
+ *    [2, 1]
+ *    [2, 2]
  *
- * Examples:
+ *  If +n+ is zero, calls the block once with an empty \Array.
+ *
+ *  If +n+ is negative, does not call the block:
+ *
+ *    a.repeated_permutation(-1) {|permutation| fail 'Cannot happen' }
+ *
+ *  Returns a new \Enumerator if no block given:
+ *
+ *    a = [0, 1, 2]
+ *    a.repeated_permutation(2) # => #<Enumerator: [0, 1, 2]:permutation(2)>
+ *
+ *  Using Enumerators, it's convenient to show the permutations and counts
+ *  for some values of +n+:
+ *
+ *    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]]
  *
- *     a = [1, 2]
- *     a.repeated_permutation(1).to_a  #=> [[1], [2]]
- *     a.repeated_permutation(2).to_a  #=> [[1,1],[1,2],[2,1],[2,2]]
- *     a.repeated_permutation(3).to_a  #=> [[1,1,1],[1,1,2],[1,2,1],[1,2,2],
- *                                     #    [2,1,1],[2,1,2],[2,2,1],[2,2,2]]
- *     a.repeated_permutation(0).to_a  #=> [[]] # one permutation of length 0
  */
-
 static VALUE
 rb_ary_repeated_permutation(VALUE ary, VALUE num)
 {
@@ -7074,25 +7431,25 @@ rb_ary_repeated_permutation(VALUE ary, VALUE num)
     r = NUM2LONG(num);                    /* Permutation size from argument */
 
     if (r < 0) {
-	/* no permutations: yield nothing */
+        /* no permutations: yield nothing */
     }
     else if (r == 0) { /* exactly one permutation: the zero-length array */
-	rb_yield(rb_ary_new2(0));
+        rb_yield(rb_ary_new2(0));
     }
     else if (r == 1) { /* this is a special, easy case */
-	for (i = 0; i < RARRAY_LEN(ary); i++) {
-	    rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
-	}
+        for (i = 0; i < RARRAY_LEN(ary); i++) {
+            rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
+        }
     }
     else {             /* this is the general case */
-	volatile VALUE t0;
-	long *p = ALLOCV_N(long, t0, r);
-	VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
-	RBASIC_CLEAR_CLASS(ary0);
+        volatile VALUE t0;
+        long *p = ALLOCV_N(long, t0, r);
+        VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
+        RBASIC_CLEAR_CLASS(ary0);
 
-	rpermute0(n, r, p, ary0); /* compute and yield repeated permutations */
-	ALLOCV_END(t0);
-	RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
+        rpermute0(n, r, p, ary0); /* compute and yield repeated permutations */
+        ALLOCV_END(t0);
+        RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
     }
     return ary;
 }
@@ -7104,19 +7461,19 @@ rcombinate0(const long n, const long r, long *const p, const long rest, const VA
 
     p[index] = i;
     for (;;) {
-	if (++index < r-1) {
-	    p[index] = i;
-	    continue;
-	}
-	for (; i < n; ++i) {
-	    p[index] = i;
-	    if (!yield_indexed_values(values, r, p)) {
-		rb_raise(rb_eRuntimeError, "repeated combination reentered");
-	    }
-	}
-	do {
-	    if (index <= 0) return;
-	} while ((i = ++p[--index]) >= n);
+        if (++index < r-1) {
+            p[index] = i;
+            continue;
+        }
+        for (; i < n; ++i) {
+            p[index] = i;
+            if (!yield_indexed_values(values, r, p)) {
+                rb_raise(rb_eRuntimeError, "repeated combination reentered");
+            }
+        }
+        do {
+            if (index <= 0) return;
+        } while ((i = ++p[--index]) >= n);
     }
 }
 
@@ -7126,35 +7483,71 @@ rb_ary_repeated_combination_size(VALUE ary, VALUE args, VALUE eobj)
     long n = RARRAY_LEN(ary);
     long k = NUM2LONG(RARRAY_AREF(args, 0));
     if (k == 0) {
-	return LONG2FIX(1);
+        return LONG2FIX(1);
     }
     return binomial_coefficient(k, n + k - 1);
 }
 
 /*
  *  call-seq:
- *     ary.repeated_combination(n) {|c| block}   -> ary
- *     ary.repeated_combination(n)               -> Enumerator
+ *    array.repeated_combination(n) {|combination| ... } -> self
+ *    array.repeated_combination(n) -> new_enumerator
+ *
+ *  Calls the block with each repeated combination of length +n+ 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:
+ *
+ *    [0]
+ *    [1]
+ *    [2]
+ *
+ *  +n+ = 2:
+ *
+ *    a.repeated_combination(2) {|combination| p combination }
  *
- * When invoked with a block, yields all repeated combinations of length +n+ of
- * elements from the array and then returns the array itself.
+ *  Output:
+ *
+ *    [0, 0]
+ *    [0, 1]
+ *    [0, 2]
+ *    [1, 1]
+ *    [1, 2]
+ *    [2, 2]
+ *
+ *  If +n+ is zero, calls the block once with an empty \Array.
  *
- * The implementation makes no guarantees about the order in which the repeated
- * combinations are yielded.
+ *  If +n+ is negative, does not call the block:
+ *
+ *    a.repeated_combination(-1) {|combination| fail 'Cannot happen' }
+ *
+ *  Returns a new \Enumerator if no block given:
  *
- * If no block is given, an Enumerator is returned instead.
+ *    a = [0, 1, 2]
+ *    a.repeated_combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>
  *
- * Examples:
+ *  Using Enumerators, it's convenient to show the combinations and counts
+ *  for some values of +n+:
  *
- *   a = [1, 2, 3]
- *   a.repeated_combination(1).to_a  #=> [[1], [2], [3]]
- *   a.repeated_combination(2).to_a  #=> [[1,1],[1,2],[1,3],[2,2],[2,3],[3,3]]
- *   a.repeated_combination(3).to_a  #=> [[1,1,1],[1,1,2],[1,1,3],[1,2,2],[1,2,3],
- *                                   #    [1,3,3],[2,2,2],[2,2,3],[2,3,3],[3,3,3]]
- *   a.repeated_combination(4).to_a  #=> [[1,1,1,1],[1,1,1,2],[1,1,1,3],[1,1,2,2],[1,1,2,3],
- *                                   #    [1,1,3,3],[1,2,2,2],[1,2,2,3],[1,2,3,3],[1,3,3,3],
- *                                   #    [2,2,2,2],[2,2,2,3],[2,2,3,3],[2,3,3,3],[3,3,3,3]]
- *   a.repeated_combination(0).to_a  #=> [[]] # one combination of length 0
+ *    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]]
  *
  */
 
@@ -7167,58 +7560,97 @@ rb_ary_repeated_combination(VALUE ary, VALUE num)
     RETURN_SIZED_ENUMERATOR(ary, 1, &num, rb_ary_repeated_combination_size);   /* Return enumerator if no block */
     len = RARRAY_LEN(ary);
     if (n < 0) {
-	/* yield nothing */
+        /* yield nothing */
     }
     else if (n == 0) {
-	rb_yield(rb_ary_new2(0));
+        rb_yield(rb_ary_new2(0));
     }
     else if (n == 1) {
-	for (i = 0; i < RARRAY_LEN(ary); i++) {
-	    rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
-	}
+        for (i = 0; i < RARRAY_LEN(ary); i++) {
+            rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
+        }
     }
     else if (len == 0) {
-	/* yield nothing */
+        /* yield nothing */
     }
     else {
-	volatile VALUE t0;
-	long *p = ALLOCV_N(long, t0, n);
-	VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
-	RBASIC_CLEAR_CLASS(ary0);
+        volatile VALUE t0;
+        long *p = ALLOCV_N(long, t0, n);
+        VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
+        RBASIC_CLEAR_CLASS(ary0);
 
-	rcombinate0(len, n, p, n, ary0); /* compute and yield repeated combinations */
-	ALLOCV_END(t0);
-	RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
+        rcombinate0(len, n, p, n, ary0); /* compute and yield repeated combinations */
+        ALLOCV_END(t0);
+        RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
     }
     return ary;
 }
 
 /*
  *  call-seq:
- *     ary.product(other_ary, ...)                -> new_ary
- *     ary.product(other_ary, ...) {|p| block}    -> ary
+ *    array.product(*other_arrays) -> new_array
+ *    array.product(*other_arrays) {|combination| ... } -> self
+ *
+ *  Computes and returns or yields 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:
+ *
+ *    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]]
  *
- *  Returns an array of all combinations of elements from all arrays.
+ *  If any argument is an empty \Array, returns an empty \Array.
  *
- *  The length of the returned array is the product of the length of +self+ and
- *  the argument arrays.
+ *  If no argument is given, returns an \Array of 1-element Arrays,
+ *  each containing an element of +self+:
  *
- *  If given a block, #product will yield all combinations and return +self+
- *  instead.
+ *    a.product # => [[0], [1], [2]]
+ *
+ *  When a block is given, yields each combination as an \Array; returns +self+:
+ *
+ *    a.product(a1) {|combination| p combination }
+ *
+ *  Output:
+ *
+ *    [0, 3]
+ *    [0, 4]
+ *    [1, 3]
+ *    [1, 4]
+ *    [2, 3]
+ *    [2, 4]
+ *
+ *  If any argument is an empty \Array, does not call the block:
+ *
+ *    a.product(a1, a2, []) {|combination| fail 'Cannot happen' }
+ *
+ *  If no argument is given, yields each element of +self+ as a 1-element \Array:
+ *
+ *    a.product {|combination| p combination }
+ *
+ *  Output:
+ *
+ *    [0]
+ *    [1]
+ *    [2]
  *
- *     [1,2,3].product([4,5])     #=> [[1,4],[1,5],[2,4],[2,5],[3,4],[3,5]]
- *     [1,2].product([1,2])       #=> [[1,1],[1,2],[2,1],[2,2]]
- *     [1,2].product([3,4],[5,6]) #=> [[1,3,5],[1,3,6],[1,4,5],[1,4,6],
- *                                #     [2,3,5],[2,3,6],[2,4,5],[2,4,6]]
- *     [1,2].product()            #=> [[1],[2]]
- *     [1,2].product([])          #=> []
  */
 
 static VALUE
 rb_ary_product(int argc, VALUE *argv, VALUE ary)
 {
     int n = argc+1;    /* How many arrays we're operating on */
-    volatile VALUE t0 = tmpary(n);
+    volatile VALUE t0 = rb_ary_hidden_new(n);
     volatile VALUE t1 = Qundef;
     VALUE *arrays = RARRAY_PTR(t0); /* The arrays we're computing the product of */
     int *counters = ALLOCV_N(int, t1, n); /* The current position in each one */
@@ -7239,64 +7671,64 @@ rb_ary_product(int argc, VALUE *argv, VALUE ary)
 
     /* Otherwise, allocate and fill in an array of results */
     if (rb_block_given_p()) {
-	/* Make defensive copies of arrays; exit if any is empty */
-	for (i = 0; i < n; i++) {
-	    if (RARRAY_LEN(arrays[i]) == 0) goto done;
-	    arrays[i] = ary_make_shared_copy(arrays[i]);
-	}
+        /* Make defensive copies of arrays; exit if any is empty */
+        for (i = 0; i < n; i++) {
+            if (RARRAY_LEN(arrays[i]) == 0) goto done;
+            arrays[i] = ary_make_shared_copy(arrays[i]);
+        }
     }
     else {
-	/* Compute the length of the result array; return [] if any is empty */
-	for (i = 0; i < n; i++) {
-	    long k = RARRAY_LEN(arrays[i]);
-	    if (k == 0) {
-		result = rb_ary_new2(0);
-		goto done;
-	    }
+        /* Compute the length of the result array; return [] if any is empty */
+        for (i = 0; i < n; i++) {
+            long k = RARRAY_LEN(arrays[i]);
+            if (k == 0) {
+                result = rb_ary_new2(0);
+                goto done;
+            }
             if (MUL_OVERFLOW_LONG_P(resultlen, k))
-		rb_raise(rb_eRangeError, "too big to product");
-	    resultlen *= k;
-	}
-	result = rb_ary_new2(resultlen);
+                rb_raise(rb_eRangeError, "too big to product");
+            resultlen *= k;
+        }
+        result = rb_ary_new2(resultlen);
     }
     for (;;) {
-	int m;
-	/* fill in one subarray */
-	VALUE subarray = rb_ary_new2(n);
-	for (j = 0; j < n; j++) {
-	    rb_ary_push(subarray, rb_ary_entry(arrays[j], counters[j]));
-	}
-
-	/* put it on the result array */
-	if (NIL_P(result)) {
-	    FL_SET(t0, FL_USER5);
-	    rb_yield(subarray);
-	    if (! FL_TEST(t0, FL_USER5)) {
-		rb_raise(rb_eRuntimeError, "product reentered");
-	    }
-	    else {
-		FL_UNSET(t0, FL_USER5);
-	    }
-	}
-	else {
-	    rb_ary_push(result, subarray);
-	}
-
-	/*
-	 * Increment the last counter.  If it overflows, reset to 0
-	 * and increment the one before it.
-	 */
-	m = n-1;
-	counters[m]++;
-	while (counters[m] == RARRAY_LEN(arrays[m])) {
-	    counters[m] = 0;
-	    /* If the first counter overflows, we are done */
-	    if (--m < 0) goto done;
-	    counters[m]++;
-	}
+        int m;
+        /* fill in one subarray */
+        VALUE subarray = rb_ary_new2(n);
+        for (j = 0; j < n; j++) {
+            rb_ary_push(subarray, rb_ary_entry(arrays[j], counters[j]));
+        }
+
+        /* put it on the result array */
+        if (NIL_P(result)) {
+            FL_SET(t0, RARRAY_SHARED_ROOT_FLAG);
+            rb_yield(subarray);
+            if (!FL_TEST(t0, RARRAY_SHARED_ROOT_FLAG)) {
+                rb_raise(rb_eRuntimeError, "product reentered");
+            }
+            else {
+                FL_UNSET(t0, RARRAY_SHARED_ROOT_FLAG);
+            }
+        }
+        else {
+            rb_ary_push(result, subarray);
+        }
+
+        /*
+         * Increment the last counter.  If it overflows, reset to 0
+         * and increment the one before it.
+         */
+        m = n-1;
+        counters[m]++;
+        while (counters[m] == RARRAY_LEN(arrays[m])) {
+            counters[m] = 0;
+            /* If the first counter overflows, we are done */
+            if (--m < 0) goto done;
+            counters[m]++;
+        }
     }
+
 done:
-    tmpary_discard(t0);
     ALLOCV_END(t1);
 
     return NIL_P(result) ? ary : result;
@@ -7304,16 +7736,19 @@ done:
 
 /*
  *  call-seq:
- *     ary.take(n)               -> new_ary
- *
- *  Returns first +n+ elements from the array.
+ *    array.take(n) -> new_array
  *
- *  If a negative number is given, raises an ArgumentError.
+ *  Returns a new \Array containing the first +n+ element of +self+,
+ *  where +n+ is a non-negative \Integer;
+ *  does not modify +self+.
  *
- *  See also Array#drop
+ *  Examples:
  *
- *     a = [1, 2, 3, 4, 5, 0]
- *     a.take(3)             #=> [1, 2, 3]
+ *    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]
  *
  */
 
@@ -7322,25 +7757,31 @@ rb_ary_take(VALUE obj, VALUE n)
 {
     long len = NUM2LONG(n);
     if (len < 0) {
-	rb_raise(rb_eArgError, "attempt to take negative size");
+        rb_raise(rb_eArgError, "attempt to take negative size");
     }
     return rb_ary_subseq(obj, 0, len);
 }
 
 /*
  *  call-seq:
- *     ary.take_while {|obj| block}    -> new_ary
- *     ary.take_while                  -> Enumerator
+ *    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+.
  *
- *  Passes elements to the block until the block returns +nil+ or +false+, then
- *  stops iterating and returns an array of all prior elements.
+ *  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:
  *
- *  If no block is given, an Enumerator is returned instead.
+ *    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]
  *
- *  See also Array#drop_while
+ *  With no block given, returns a new \Enumerator:
  *
- *     a = [1, 2, 3, 4, 5, 0]
- *     a.take_while {|i| i < 3}    #=> [1, 2]
+ *    [0, 1].take_while # => #<Enumerator: [0, 1]:take_while>
  *
  */
 
@@ -7351,24 +7792,25 @@ rb_ary_take_while(VALUE ary)
 
     RETURN_ENUMERATOR(ary, 0, 0);
     for (i = 0; i < RARRAY_LEN(ary); i++) {
-	if (!RTEST(rb_yield(RARRAY_AREF(ary, i)))) break;
+        if (!RTEST(rb_yield(RARRAY_AREF(ary, i)))) break;
     }
     return rb_ary_take(ary, LONG2FIX(i));
 }
 
 /*
  *  call-seq:
- *     ary.drop(n)               -> new_ary
+ *    array.drop(n) -> new_array
  *
- *  Drops first +n+ elements from +ary+ and returns the rest of the elements in
- *  an array.
+ *  Returns a new \Array containing all but the first +n+ element of +self+,
+ *  where +n+ is a non-negative \Integer;
+ *  does not modify +self+.
  *
- *  If a negative number is given, raises an ArgumentError.
- *
- *  See also Array#take
+ *  Examples:
  *
- *     a = [1, 2, 3, 4, 5, 0]
- *     a.drop(3)             #=> [4, 5, 0]
+ *    a = [0, 1, 2, 3, 4, 5]
+ *    a.drop(0) # => [0, 1, 2, 3, 4, 5]
+ *    a.drop(1) # => [1, 2, 3, 4, 5]
+ *    a.drop(2) # => [2, 3, 4, 5]
  *
  */
 
@@ -7378,29 +7820,32 @@ rb_ary_drop(VALUE ary, VALUE n)
     VALUE result;
     long pos = NUM2LONG(n);
     if (pos < 0) {
-	rb_raise(rb_eArgError, "attempt to drop negative size");
+        rb_raise(rb_eArgError, "attempt to drop negative size");
     }
 
     result = rb_ary_subseq(ary, pos, RARRAY_LEN(ary));
-    if (result == Qnil) result = rb_ary_new();
+    if (NIL_P(result)) result = rb_ary_new();
     return result;
 }
 
 /*
  *  call-seq:
- *     ary.drop_while {|obj| block}     -> new_ary
- *     ary.drop_while                  -> Enumerator
+ *    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+.
  *
- *  Drops elements up to, but not including, the first element for which the
- *  block returns +nil+ or +false+ and returns an array containing the
- *  remaining elements.
+ *  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:
  *
- *  If no block is given, an Enumerator is returned instead.
+ *    a = [0, 1, 2, 3, 4, 5]
+ *    a.drop_while {|element| element < 3 } # => [3, 4, 5]
  *
- *  See also Array#take_while
+ *  With no block given, returns a new \Enumerator:
  *
- *     a = [1, 2, 3, 4, 5, 0]
- *     a.drop_while {|i| i < 3 }   #=> [3, 4, 5, 0]
+ *    [0, 1].drop_while # => # => #<Enumerator: [0, 1]:drop_while>
  *
  */
 
@@ -7411,17 +7856,42 @@ rb_ary_drop_while(VALUE ary)
 
     RETURN_ENUMERATOR(ary, 0, 0);
     for (i = 0; i < RARRAY_LEN(ary); i++) {
-	if (!RTEST(rb_yield(RARRAY_AREF(ary, i)))) break;
+        if (!RTEST(rb_yield(RARRAY_AREF(ary, i)))) break;
     }
     return rb_ary_drop(ary, LONG2FIX(i));
 }
 
 /*
  *  call-seq:
- *     ary.any? [{|obj| block}  ]   -> true or false
- *     ary.any?(pattern)            -> true or false
+ *    array.any? -> true or false
+ *    array.any? {|element| ... } -> true or false
+ *    array.any?(obj) -> true or false
+ *
+ *  Returns +true+ if any element of +self+ meets a given criterion.
+ *
+ *  With no block given and no argument, returns +true+ if +self+ has any truthy element,
+ *  +false+ otherwise:
+ *
+ *    [nil, 0, false].any? # => true
+ *    [nil, false].any? # => false
+ *    [].any? # => false
+ *
+ *  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:
+ *
+ *    [0, 1, 2].any? {|element| element > 1 } # => true
+ *    [0, 1, 2].any? {|element| element > 2 } # => false
+ *
+ *  If argument +obj+ is given, returns +true+ if +obj+.<tt>===</tt> any element,
+ *  +false+ otherwise:
  *
- *  See also Enumerable#any?
+ *    ['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
+ *
+ *  Related: Enumerable#any?
  */
 
 static VALUE
@@ -7435,9 +7905,9 @@ rb_ary_any_p(int argc, VALUE *argv, VALUE ary)
         if (rb_block_given_p()) {
             rb_warn("given block not used");
         }
-	for (i = 0; i < RARRAY_LEN(ary); ++i) {
-	    if (RTEST(rb_funcall(argv[0], idEqq, 1, RARRAY_AREF(ary, i)))) return Qtrue;
-	}
+        for (i = 0; i < RARRAY_LEN(ary); ++i) {
+            if (RTEST(rb_funcall(argv[0], idEqq, 1, RARRAY_AREF(ary, i)))) return Qtrue;
+        }
     }
     else if (!rb_block_given_p()) {
         for (i = 0; i < len; ++i) {
@@ -7445,19 +7915,43 @@ rb_ary_any_p(int argc, VALUE *argv, VALUE ary)
         }
     }
     else {
-	for (i = 0; i < RARRAY_LEN(ary); ++i) {
-	    if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) return Qtrue;
-	}
+        for (i = 0; i < RARRAY_LEN(ary); ++i) {
+            if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) return Qtrue;
+        }
     }
     return Qfalse;
 }
 
 /*
  *  call-seq:
- *     ary.all? [{|obj| block}  ]   -> true or false
- *     ary.all?(pattern)            -> true or false
+ *    array.all? -> true or false
+ *    array.all? {|element| ... } -> true or false
+ *    array.all?(obj) -> true or false
+ *
+ *  Returns +true+ if all elements of +self+ meet a given criterion.
+ *
+ *  With no block given and no argument, returns +true+ if +self+ contains only truthy elements,
+ *  +false+ otherwise:
+ *
+ *    [0, 1, :foo].all? # => true
+ *    [0, nil, 2].all? # => false
+ *    [].all? # => true
+ *
+ *  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:
  *
- *  See also Enumerable#all?
+ *    [0, 1, 2].all? { |element| element < 3 } # => true
+ *    [0, 1, 2].all? { |element| element < 2 } # => false
+ *
+ *  If argument +obj+ is given, returns +true+ if <tt>obj.===</tt> every element, +false+ otherwise:
+ *
+ *    ['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
+ *
+ *  Related: Enumerable#all?
  */
 
 static VALUE
@@ -7490,10 +7984,34 @@ rb_ary_all_p(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *     ary.none? [{|obj| block}  ]   -> true or false
- *     ary.none?(pattern)            -> true or false
+ *    array.none? -> true or false
+ *    array.none? {|element| ... } -> true or false
+ *    array.none?(obj) -> true or false
+ *
+ *  Returns +true+ if no element of +self+ meet a given criterion.
+ *
+ *  With no block given and no argument, returns +true+ if +self+ has no truthy elements,
+ *  +false+ otherwise:
+ *
+ *    [nil, false].none? # => true
+ *    [nil, 0, false].none? # => false
+ *    [].none? # => true
+ *
+ *  With a block given and no argument, 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
  *
- *  See also Enumerable#none?
+ *  Related: Enumerable#none?
  */
 
 static VALUE
@@ -7526,10 +8044,38 @@ rb_ary_none_p(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *     ary.one? [{|obj| block}  ]   -> true or false
- *     ary.one?(pattern)            -> true or false
+ *    array.one? -> true or false
+ *    array.one? {|element| ... } -> true or false
+ *    array.one?(obj) -> true or false
  *
- *  See also Enumerable#one?
+ *  Returns +true+ if exactly one element of +self+ meets a given criterion.
+ *
+ *  With no block given and no argument, returns +true+ if +self+ has exactly one truthy element,
+ *  +false+ otherwise:
+ *
+ *    [nil, 0].one? # => true
+ *    [0, 0].one? # => false
+ *    [nil, nil].one? # => false
+ *    [].one? # => false
+ *
+ *  With a block given and no argument, 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,
+ *  +false+ otherwise:
+ *
+ *    [0, 1, 2].one?(0) # => true
+ *    [0, 0, 1].one?(0) # => false
+ *    [1, 1, 2].one?(0) # => false
+ *    ['food', 'drink'].one?(/bar/) # => false
+ *    ['food', 'drink'].one?(/foo/) # => true
+ *    [].one?(/foo/) # => false
+ *
+ *  Related: Enumerable#one?
  */
 
 static VALUE
@@ -7571,19 +8117,22 @@ rb_ary_one_p(int argc, VALUE *argv, VALUE ary)
 }
 
 /*
- * call-seq:
- *   ary.dig(idx, ...)                 -> object
+ *  call-seq:
+ *    array.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.
+ *  See {Dig Methods}[rdoc-ref:dig_methods.rdoc].
  *
- * Extracts the nested value specified by the sequence of <i>idx</i>
- * objects by calling +dig+ at each step, returning +nil+ if any
- * intermediate step is +nil+.
+ *  Examples:
  *
- *   a = [[1, [2, 3]]]
+ *    a = [:foo, [:bar, :baz, [:bat, :bam]]]
+ *    a.dig(1) # => [:bar, :baz, [:bat, :bam]]
+ *    a.dig(1, 2) # => [:bat, :bam]
+ *    a.dig(1, 2, 0) # => :bat
+ *    a.dig(1, 2, 3) # => nil
  *
- *   a.dig(0, 1, 1)                    #=> 3
- *   a.dig(1, 2, 3)                    #=> nil
- *   a.dig(0, 0, 0)                    #=> TypeError: Integer does not have #dig method
- *   [42, {foo: :bar}].dig(1, :foo)    #=> :bar
  */
 
 static VALUE
@@ -7601,14 +8150,8 @@ finish_exact_sum(long n, VALUE r, VALUE v, int z)
 {
     if (n != 0)
         v = rb_fix_plus(LONG2FIX(n), v);
-    if (r != Qundef) {
-	/* r can be an Integer when mathn is loaded */
-	if (FIXNUM_P(r))
-	    v = rb_fix_plus(r, v);
-	else if (RB_TYPE_P(r, T_BIGNUM))
-	    v = rb_big_plus(r, v);
-	else
-	    v = rb_rational_plus(r, v);
+    if (!UNDEF_P(r)) {
+        v = rb_rational_plus(r, v);
     }
     else if (!n && z) {
         v = rb_fix_plus(LONG2FIX(0), v);
@@ -7618,43 +8161,41 @@ finish_exact_sum(long n, VALUE r, VALUE v, int z)
 
 /*
  * call-seq:
- *   ary.sum(init=0)                    -> number
- *   ary.sum(init=0) {|e| expr }        -> number
+ *   array.sum(init = 0) -> object
+ *   array.sum(init = 0) {|element| ... } -> object
  *
- * Returns the sum of elements.
- * For example, [e1, e2, e3].sum returns init + e1 + e2 + e3.
+ *  When no block is given, returns the object equivalent to:
  *
- * If a block is given, the block is applied to each element
- * before addition.
+ *    sum = init
+ *    array.each {|element| sum += element }
+ *    sum
  *
- * If <i>ary</i> is empty, it returns <i>init</i>.
+ *  For example, <tt>[e1, e2, e3].sum</tt> returns <tt>init + e1 + e2 + e3</tt>.
  *
- *   [].sum                             #=> 0
- *   [].sum(0.0)                        #=> 0.0
- *   [1, 2, 3].sum                      #=> 6
- *   [3, 5.5].sum                       #=> 8.5
- *   [2.5, 3.0].sum(0.0) {|e| e * e }   #=> 15.25
- *   [Object.new].sum                   #=> TypeError
- *
- * The (arithmetic) mean value of an array can be obtained as follows.
+ *  Examples:
  *
- *   mean = ary.sum(0.0) / ary.length
+ *    a = [0, 1, 2, 3]
+ *    a.sum # => 6
+ *    a.sum(100) # => 106
  *
- * This method can be used for non-numeric objects by
- * explicit <i>init</i> argument.
+ *  The elements need not be numeric, but must be <tt>+</tt>-compatible
+ *  with each other and with +init+:
  *
- *   ["a", "b", "c"].sum("")            #=> "abc"
- *   [[1], [[2]], [3]].sum([])          #=> [1, [2], 3]
+ *    a = ['abc', 'def', 'ghi']
+ *    a.sum('jkl') # => "jklabcdefghi"
  *
- * However, Array#join and Array#flatten is faster than Array#sum for
- * array of strings and array of arrays.
+ *  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:
  *
- *   ["a", "b", "c"].join               #=> "abc"
- *   [[1], [[2]], [3]].flatten(1)       #=> [1, [2], 3]
+ *    a = ['zero', 1, :two]
+ *    s = a.sum('Coerced and concatenated: ') {|element| element.to_s }
+ *    s # => "Coerced and concatenated: zero1two"
  *
+ *  Notes:
  *
- * Array#sum method may not respect method redefinition of "+" methods
- * such as Integer#+.
+ *  - Array#join and Array#flatten may be faster than Array#sum
+ *    for an \Array of Strings or an \Array of Arrays.
+ *  - Array#sum method may not respect method redefinition of "+" methods such as Integer#+.
  *
  */
 
@@ -7685,10 +8226,10 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
                 n = 0;
             }
         }
-        else if (RB_TYPE_P(e, T_BIGNUM))
+        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);
@@ -7705,7 +8246,7 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
     if (RB_FLOAT_TYPE_P(e)) {
         /*
          * Kahan-Babuska balancing compensated summation algorithm
-         * See http://link.springer.com/article/10.1007/s00607-005-0139-x
+         * See https://link.springer.com/article/10.1007/s00607-005-0139-x
          */
         double f, c;
         double x, t;
@@ -7722,7 +8263,7 @@ rb_ary_sum(int argc, VALUE *argv, VALUE ary)
                 x = RFLOAT_VALUE(e);
             else if (FIXNUM_P(e))
                 x = FIX2LONG(e);
-            else if (RB_TYPE_P(e, T_BIGNUM))
+            else if (RB_BIGNUM_TYPE_P(e))
                 x = rb_big2dbl(e);
             else if (RB_TYPE_P(e, T_RATIONAL))
                 x = rb_num2dbl(e);
@@ -7775,75 +8316,128 @@ rb_ary_deconstruct(VALUE ary)
 }
 
 /*
- *  An \Array is an ordered, integer-indexed collection of objects,
- *  called _elements_.  Any object may be an \Array element.
+ *  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.
  *
  *  == \Array Indexes
  *
  *  \Array indexing starts at 0, as in C or Java.
  *
  *  A positive index is an offset from the first element:
+ *
  *  - Index 0 indicates the first element.
  *  - Index 1 indicates the second element.
  *  - ...
  *
  *  A negative index is an offset, backwards, from the end of the array:
+ *
  *  - Index -1 indicates the last element.
  *  - Index -2 indicates the next-to-last element.
  *  - ...
  *
- *  A non-negative index is <i>in range</i> if it is smaller than
+ *  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:
+ *
  *  - Indexes 0 through 2 are in range.
  *  - Index 3 is out of range.
  *
- *  A negative index is <i>in range</i> if its absolute value is
+ *  A negative index is <i>in range</i> if and only if its absolute value is
  *  not larger than the size of the array.  For a 3-element array:
+ *
  *  - Indexes -1 through -3 are in range.
  *  - Index -4 is out of range.
  *
+ *  Although the effective index into an array is always an integer,
+ *  some methods (both within and outside of class \Array)
+ *  accept one or more non-integer arguments that are
+ *  {integer-convertible objects}[rdoc-ref:implicit_conversion.rdoc@Integer-Convertible+Objects].
+ *
+ *
  *  == Creating Arrays
  *
- *  A new array can be created by using the literal constructor
- *  <code>[]</code>.  Arrays can contain different types of objects.  For
- *  example, the array below contains an Integer, a String and a Float:
+ *  You can create an \Array object explicitly with:
  *
- *     ary = [1, "two", 3.0] #=> [1, "two", 3.0]
+ *  - An {array literal}[rdoc-ref:literals.rdoc@Array+Literals]:
  *
- *  An array can also be created by explicitly calling Array.new with zero, one
- *  (the initial size of the Array) or two arguments (the initial size and a
- *  default object).
+ *      [1, 'one', :one, [2, 'two', :two]]
  *
- *     ary = Array.new    #=> []
- *     Array.new(3)       #=> [nil, nil, nil]
- *     Array.new(3, true) #=> [true, true, true]
+ *  - A {%w or %W: string-array Literal}[rdoc-ref:literals.rdoc@25w+and+-25W-3A+String-Array+Literals]:
  *
- *  Note that the second argument populates the array with references to the
- *  same object.  Therefore, it is only recommended in cases when you need to
- *  instantiate arrays with natively immutable objects such as Symbols,
- *  numbers, true or false.
+ *      %w[foo bar baz] # => ["foo", "bar", "baz"]
+ *      %w[1 % *]       # => ["1", "%", "*"]
  *
- *  To create an array with separate objects a block can be passed instead.
- *  This method is safe to use with mutable objects such as hashes, strings or
- *  other arrays:
+ *  - A {%i pr %I: symbol-array Literal}[rdoc-ref:literals.rdoc@25i+and+-25I-3A+Symbol-Array+Literals]:
  *
- *     Array.new(4) {Hash.new}    #=> [{}, {}, {}, {}]
- *     Array.new(4) {|i| i.to_s } #=> ["0", "1", "2", "3"]
+ *      %i[foo bar baz] # => [:foo, :bar, :baz]
+ *      %i[1 % *]       # => [:"1", :%, :*]
  *
- *  This is also a quick way to build up multi-dimensional arrays:
+ *  - \Method Kernel#Array:
  *
- *     empty_table = Array.new(3) {Array.new(3)}
- *     #=> [[nil, nil, nil], [nil, nil, nil], [nil, nil, nil]]
+ *      Array(["a", "b"])             # => ["a", "b"]
+ *      Array(1..5)                   # => [1, 2, 3, 4, 5]
+ *      Array(key: :value)            # => [[:key, :value]]
+ *      Array(nil)                    # => []
+ *      Array(1)                      # => [1]
+ *      Array({:a => "a", :b => "b"}) # => [[:a, "a"], [:b, "b"]]
  *
- *  An array can also be created by using the Array() method, provided by
- *  Kernel, which tries to call #to_ary, then #to_a on its argument.
+ *  - \Method Array.new:
  *
- *	Array({:a => "a", :b => "b"}) #=> [[:a, "a"], [:b, "b"]]
+ *      Array.new               # => []
+ *      Array.new(3)            # => [nil, nil, nil]
+ *      Array.new(4) {Hash.new} # => [{}, {}, {}, {}]
+ *      Array.new(3, true)      # => [true, true, true]
+ *
+ *    Note that the last example above populates the array
+ *    with references to the same object.
+ *    This is recommended only in cases where that object is a natively immutable object
+ *    such as a symbol, a numeric, +nil+, +true+, or +false+.
+ *
+ *    Another way to create an array with various objects, using a block;
+ *    this usage is safe for mutable objects such as hashes, strings or
+ *    other arrays:
+ *
+ *      Array.new(4) {|i| i.to_s } # => ["0", "1", "2", "3"]
+ *
+ *    Here is a way to create a multi-dimensional array:
+ *
+ *      Array.new(3) {Array.new(3)}
+ *      # => [[nil, nil, nil], [nil, nil, nil], [nil, nil, nil]]
+ *
+ *  A number of Ruby methods, both in the core and in the standard library,
+ *  provide instance method +to_a+, which converts an object to an array.
+ *
+ *  - ARGF#to_a
+ *  - Array#to_a
+ *  - Enumerable#to_a
+ *  - Hash#to_a
+ *  - MatchData#to_a
+ *  - NilClass#to_a
+ *  - OptionParser#to_a
+ *  - Range#to_a
+ *  - Set#to_a
+ *  - Struct#to_a
+ *  - Time#to_a
+ *  - Benchmark::Tms#to_a
+ *  - CSV::Table#to_a
+ *  - Enumerator::Lazy#to_a
+ *  - Gem::List#to_a
+ *  - Gem::NameTuple#to_a
+ *  - Gem::Platform#to_a
+ *  - Gem::RequestSet::Lockfile::Tokenizer#to_a
+ *  - Gem::SourceList#to_a
+ *  - OpenSSL::X509::Extension#to_a
+ *  - OpenSSL::X509::Name#to_a
+ *  - Racc::ISet#to_a
+ *  - Rinda::RingFinger#to_a
+ *  - Ripper::Lexer::Elem#to_a
+ *  - RubyVM::InstructionSequence#to_a
+ *  - YAML::DBM#to_a
  *
  *  == 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
+ *  \Array class has proprietary methods for accessing, searching and otherwise
  *  manipulating arrays.
  *
  *  Some of the more common ones are illustrated below.
@@ -7891,7 +8485,7 @@ rb_ary_deconstruct(VALUE ary)
  *
  *     arr.drop(3) #=> [4, 5, 6]
  *
- *  == Obtaining Information about an Array
+ *  == Obtaining Information about an \Array
  *
  *  Arrays keep track of their own length at all times.  To query an array
  *  about the number of elements it contains, use #length, #count or #size.
@@ -7929,7 +8523,7 @@ rb_ary_deconstruct(VALUE ary)
  *     arr.insert(3, 'orange', 'pear', 'grapefruit')
  *     #=> [0, 1, 2, "orange", "pear", "grapefruit", "apple", 3, 4, 5, 6]
  *
- *  == Removing Items from an Array
+ *  == Removing Items from an \Array
  *
  *  The method #pop removes the last element in an array and returns it:
  *
@@ -7971,9 +8565,9 @@ rb_ary_deconstruct(VALUE ary)
  *
  *  == Iterating over Arrays
  *
- *  Like all classes that include the Enumerable module, Array has an each
+ *  Like all classes that include the Enumerable module, \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's #each, all elements in the \Array instance are yielded to
  *  the supplied block in sequence.
  *
  *  Note that this operation leaves the array unchanged.
@@ -7999,7 +8593,8 @@ rb_ary_deconstruct(VALUE ary)
  *     arr.map! {|a| a**2}   #=> [1, 4, 9, 16, 25]
  *     arr                   #=> [1, 4, 9, 16, 25]
  *
- *  == Selecting Items from an Array
+ *
+ *  == Selecting Items from an \Array
  *
  *  Elements can be selected from an array according to criteria defined in a
  *  block.  The selection can happen in a destructive or a non-destructive
@@ -8029,18 +8624,199 @@ rb_ary_deconstruct(VALUE ary)
  *     arr = [1, 2, 3, 4, 5, 6]
  *     arr.keep_if {|a| a < 4}   #=> [1, 2, 3]
  *     arr                       #=> [1, 2, 3]
+ *
+ *  == What's Here
+ *
+ *  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],
+ *    which provides dozens of additional methods.
+ *
+ *  Here, class \Array provides methods that are useful for:
+ *
+ *  - {Creating an Array}[rdoc-ref:Array@Methods+for+Creating+an+Array]
+ *  - {Querying}[rdoc-ref:Array@Methods+for+Querying]
+ *  - {Comparing}[rdoc-ref:Array@Methods+for+Comparing]
+ *  - {Fetching}[rdoc-ref:Array@Methods+for+Fetching]
+ *  - {Assigning}[rdoc-ref:Array@Methods+for+Assigning]
+ *  - {Deleting}[rdoc-ref:Array@Methods+for+Deleting]
+ *  - {Combining}[rdoc-ref:Array@Methods+for+Combining]
+ *  - {Iterating}[rdoc-ref:Array@Methods+for+Iterating]
+ *  - {Converting}[rdoc-ref:Array@Methods+for+Converting]
+ *  - {And more....}[rdoc-ref:Array@Other+Methods]
+ *
+ *  === Methods for Creating an \Array
+ *
+ *  - ::[]: Returns a new array populated with given objects.
+ *  - ::new: Returns a new array.
+ *  - ::try_convert: Returns a new array created from a given object.
+ *
+ *  === 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.
+ *  - #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.
+
+ *  === 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.
+ *  - #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.
+ *  - #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.
+ *  - #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.
+ *  - #shuffle: Returns elements in a random order.
+ *
+ *  === Methods for Assigning
+ *
+ *  These methods add, replace, or reorder elements in +self+.
+ *
+ *  - #[]=: 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.
+ *  - #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_by!: Replaces +self+ with its elements sorted, as determined by a given block.
+ *
+ *  === 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 +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.
+ *  - #reject!: Removes elements specified by a given block.
+ *  - #select!, #filter!: Removes elements not specified by a given block.
+ *  - #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..
+ *  - #product: Returns or yields all combinations of elements from +self+ and given arrays.
+ *
+ *  === Methods for Iterating
+ *
+ *  - #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.
+ *
+ *  === 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.
+ *  - #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.
+ *  - #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.
+ *
+ *  === Other Methods
+ *
+ *  - #*: Returns one of the following:
+ *
+ *    - With integer argument +n+, a new array that is the concatenation
+ *      of +n+ copies of +self+.
+ *    - 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.
  */
 
 void
 Init_Array(void)
 {
-#undef rb_intern
-#define rb_intern(str) rb_intern_const(str)
-
     rb_cArray  = rb_define_class("Array", rb_cObject);
     rb_include_module(rb_cArray, rb_mEnumerable);
 
     rb_define_alloc_func(rb_cArray, empty_ary_alloc);
+    rb_define_singleton_method(rb_cArray, "new", rb_ary_s_new, -1);
     rb_define_singleton_method(rb_cArray, "[]", rb_ary_s_create, -1);
     rb_define_singleton_method(rb_cArray, "try_convert", rb_ary_s_try_convert, 1);
     rb_define_method(rb_cArray, "initialize", rb_ary_initialize, -1);
@@ -8066,6 +8842,7 @@ Init_Array(void)
     rb_define_method(rb_cArray, "union", rb_ary_union_multi, -1);
     rb_define_method(rb_cArray, "difference", rb_ary_difference_multi, -1);
     rb_define_method(rb_cArray, "intersection", rb_ary_intersection_multi, -1);
+    rb_define_method(rb_cArray, "intersect?", rb_ary_intersect_p, 1);
     rb_define_method(rb_cArray, "<<", rb_ary_push, 1);
     rb_define_method(rb_cArray, "push", rb_ary_push_m, -1);
     rb_define_alias(rb_cArray,  "append", "push");
@@ -8078,7 +8855,7 @@ Init_Array(void)
     rb_define_method(rb_cArray, "each_index", rb_ary_each_index, 0);
     rb_define_method(rb_cArray, "reverse_each", rb_ary_reverse_each, 0);
     rb_define_method(rb_cArray, "length", rb_ary_length, 0);
-    rb_define_alias(rb_cArray,  "size", "length");
+    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_index", rb_ary_index, -1);
     rb_define_method(rb_cArray, "index", rb_ary_index, -1);
diff --git a/array.rb b/array.rb
index 9de9634835..b9fa9844e6 100644
--- a/array.rb
+++ b/array.rb
@@ -1,62 +1,69 @@
 class Array
   # call-seq:
-  #    ary.shuffle!              -> ary
-  #    ary.shuffle!(random: rng) -> ary
+  #    array.shuffle!(random: Random) -> array
   #
-  # Shuffles elements in +self+ in place.
-  #
-  #    a = [ 1, 2, 3 ]           #=> [1, 2, 3]
-  #    a.shuffle!                #=> [2, 3, 1]
-  #    a                         #=> [2, 3, 1]
-  #
-  # The optional +rng+ argument will be used as the random number generator.
+  # Shuffles the elements of +self+ in place.
+  #    a = [1, 2, 3] #=> [1, 2, 3]
+  #    a.shuffle!    #=> [2, 3, 1]
+  #    a             #=> [2, 3, 1]
   #
+  # The optional +random+ argument will be used as the random number generator:
   #    a.shuffle!(random: Random.new(1))  #=> [1, 3, 2]
   def shuffle!(random: Random)
     Primitive.rb_ary_shuffle_bang(random)
   end
 
   # call-seq:
-  #    ary.shuffle              -> new_ary
-  #    ary.shuffle(random: rng) -> new_ary
+  #    array.shuffle(random: Random) -> new_ary
   #
   # 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]
   #
-  #    a = [ 1, 2, 3 ]           #=> [1, 2, 3]
-  #    a.shuffle                 #=> [2, 3, 1]
-  #    a                         #=> [1, 2, 3]
-  #
-  # The optional +rng+ argument will be used as the random number generator.
-  #
+  # The optional +random+ argument will be used as the random number generator:
   #    a.shuffle(random: Random.new(1))  #=> [1, 3, 2]
   def shuffle(random: Random)
     Primitive.rb_ary_shuffle(random)
   end
 
   # call-seq:
-  #    ary.sample                  -> obj
-  #    ary.sample(random: rng)     -> obj
-  #    ary.sample(n)               -> new_ary
-  #    ary.sample(n, random: rng)  -> new_ary
-  #
-  # Choose a random element or +n+ random elements from the array.
-  #
-  # The elements are chosen by using random and unique indices into the array
-  # in order to ensure that an element doesn't repeat itself unless the array
-  # already contained duplicate elements.
+  #    array.sample(random: Random) -> object
+  #    array.sample(n, random: Random) -> new_ary
   #
-  # If the array is empty the first form returns +nil+ and the second form
-  # returns an empty array.
+  # Returns random elements from +self+.
   #
-  #    a = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]
-  #    a.sample         #=> 7
-  #    a.sample(4)      #=> [6, 4, 2, 5]
+  # 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+.
   #
-  # The optional +rng+ argument will be used as the random number generator.
+  # 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]
   def sample(n = (ary = false), random: Random)
-    Primitive.rb_ary_sample(random, n, ary)
+    if Primitive.mandatory_only?
+      # Primitive.cexpr! %{ rb_ary_sample(self, rb_cRandom, Qfalse, Qfalse) }
+      Primitive.ary_sample0
+    else
+      # Primitive.cexpr! %{ rb_ary_sample(self, random, n, ary) }
+      Primitive.ary_sample(random, n, ary)
+    end
   end
 end
diff --git a/ast.c b/ast.c
index 87c366550e..adb7287ed3 100644
--- a/ast.c
+++ b/ast.c
@@ -64,9 +64,8 @@ ast_new_internal(rb_ast_t *ast, const NODE *node)
     return obj;
 }
 
-static VALUE rb_ast_parse_str(VALUE str);
-static VALUE rb_ast_parse_file(VALUE path);
-static VALUE rb_ast_parse_array(VALUE array);
+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)
@@ -86,29 +85,33 @@ ast_parse_done(rb_ast_t *ast)
 }
 
 static VALUE
-ast_s_parse(rb_execution_context_t *ec, VALUE module, VALUE str)
+ast_s_parse(rb_execution_context_t *ec, VALUE module, VALUE str, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
-    return rb_ast_parse_str(str);
+    return rb_ast_parse_str(str, keep_script_lines, error_tolerant, keep_tokens);
 }
 
 static VALUE
-rb_ast_parse_str(VALUE str)
+rb_ast_parse_str(VALUE str, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
     rb_ast_t *ast = 0;
 
     StringValue(str);
-    ast = rb_parser_compile_string_path(ast_parse_new(), Qnil, str, 1);
+    VALUE vparser = ast_parse_new();
+    if (RTEST(keep_script_lines)) rb_parser_keep_script_lines(vparser);
+    if (RTEST(error_tolerant)) rb_parser_error_tolerant(vparser);
+    if (RTEST(keep_tokens)) rb_parser_keep_tokens(vparser);
+    ast = rb_parser_compile_string_path(vparser, Qnil, str, 1);
     return ast_parse_done(ast);
 }
 
 static VALUE
-ast_s_parse_file(rb_execution_context_t *ec, VALUE module, VALUE path)
+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);
+    return rb_ast_parse_file(path, keep_script_lines, error_tolerant, keep_tokens);
 }
 
 static VALUE
-rb_ast_parse_file(VALUE path)
+rb_ast_parse_file(VALUE path, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
     VALUE f;
     rb_ast_t *ast = 0;
@@ -117,7 +120,11 @@ rb_ast_parse_file(VALUE path)
     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("-"));
-    ast = rb_parser_compile_file_path(ast_parse_new(), Qnil, f, 1);
+    VALUE vparser = ast_parse_new();
+    if (RTEST(keep_script_lines)) rb_parser_keep_script_lines(vparser);
+    if (RTEST(error_tolerant))  rb_parser_error_tolerant(vparser);
+    if (RTEST(keep_tokens))  rb_parser_keep_tokens(vparser);
+    ast = rb_parser_compile_file_path(vparser, Qnil, f, 1);
     rb_io_close(f);
     return ast_parse_done(ast);
 }
@@ -136,12 +143,16 @@ lex_array(VALUE array, int index)
 }
 
 static VALUE
-rb_ast_parse_array(VALUE array)
+rb_ast_parse_array(VALUE array, VALUE keep_script_lines, VALUE error_tolerant, VALUE keep_tokens)
 {
     rb_ast_t *ast = 0;
 
     array = rb_check_array_type(array);
-    ast = rb_parser_compile_generic(ast_parse_new(), lex_array, Qnil, array, 1);
+    VALUE vparser = ast_parse_new();
+    if (RTEST(keep_script_lines)) rb_parser_keep_script_lines(vparser);
+    if (RTEST(error_tolerant)) rb_parser_error_tolerant(vparser);
+    if (RTEST(keep_tokens)) rb_parser_keep_tokens(vparser);
+    ast = rb_parser_compile_generic(vparser, lex_array, Qnil, array, 1);
     return ast_parse_done(ast);
 }
 
@@ -188,35 +199,69 @@ script_lines(VALUE path)
 }
 
 static VALUE
-ast_s_of(rb_execution_context_t *ec, VALUE module, VALUE body)
+node_id_for_backtrace_location(rb_execution_context_t *ec, VALUE module, VALUE location)
 {
-    VALUE path, node, lines;
     int node_id;
-    const rb_iseq_t *iseq = NULL;
 
-    if (rb_obj_is_proc(body)) {
-        iseq = vm_proc_iseq(body);
+    if (!rb_frame_info_p(location)) {
+        rb_raise(rb_eTypeError, "Thread::Backtrace::Location object expected");
+    }
 
-        if (!rb_obj_is_iseq((VALUE)iseq)) {
-            iseq = NULL;
-        }
+    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, VALUE error_tolerant, VALUE keep_tokens)
+{
+    VALUE node, lines = Qnil;
+    const rb_iseq_t *iseq;
+    int node_id;
+
+    if (rb_frame_info_p(body)) {
+        iseq = rb_get_iseq_from_frame_info(body);
+        node_id = rb_get_node_id_from_frame_info(body);
     }
     else {
-        iseq = rb_method_iseq(body);
+        iseq = NULL;
+
+        if (rb_obj_is_proc(body)) {
+            iseq = vm_proc_iseq(body);
+
+            if (!rb_obj_is_iseq((VALUE)iseq)) return Qnil;
+        }
+        else {
+            iseq = rb_method_iseq(body);
+        }
+        if (iseq) {
+            node_id = ISEQ_BODY(iseq)->location.node_id;
+        }
     }
 
-    if (!iseq) return Qnil;
+    if (!iseq) {
+        return Qnil;
+    }
+    lines = ISEQ_BODY(iseq)->variable.script_lines;
 
-    path = rb_iseq_path(iseq);
-    node_id = iseq->body->location.node_id;
-    if (!NIL_P(lines = script_lines(path))) {
-        node = rb_ast_parse_array(lines);
+    VALUE path = rb_iseq_path(iseq);
+    int e_option = RSTRING_LEN(path) == 2 && memcmp(RSTRING_PTR(path), "-e", 2) == 0;
+
+    if (NIL_P(lines) && rb_iseq_from_eval_p(iseq) && !e_option) {
+        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, error_tolerant, keep_tokens);
     }
-    else if (RSTRING_LEN(path) == 2 && memcmp(RSTRING_PTR(path), "-e", 2) == 0) {
-        node = rb_ast_parse_str(rb_e_script);
+    else if (e_option) {
+        node = rb_ast_parse_str(rb_e_script, keep_script_lines, error_tolerant, keep_tokens);
     }
     else {
-        node = rb_ast_parse_file(path);
+        node = rb_ast_parse_file(path, keep_script_lines, error_tolerant, keep_tokens);
     }
 
     return node_find(node, node_id);
@@ -246,6 +291,15 @@ ast_node_type(rb_execution_context_t *ec, VALUE self)
     return rb_sym_intern_ascii_cstr(node_type_to_str(data->node));
 }
 
+static VALUE
+ast_node_node_id(rb_execution_context_t *ec, VALUE self)
+{
+    struct ASTNodeData *data;
+    TypedData_Get_Struct(self, struct ASTNodeData, &rb_node_type, data);
+
+    return INT2FIX(nd_node_id(data->node));
+}
+
 #define NEW_CHILD(ast, node) node ? ast_new_internal(ast, node) : Qnil
 
 static VALUE
@@ -274,7 +328,7 @@ dump_block(rb_ast_t *ast, const NODE *node)
     do {
         rb_ary_push(ary, NEW_CHILD(ast, node->nd_head));
     } while (node->nd_next &&
-        nd_type(node->nd_next) == NODE_BLOCK &&
+        nd_type_p(node->nd_next, NODE_BLOCK) &&
         (node = node->nd_next, 1));
     if (node->nd_next) {
         rb_ary_push(ary, NEW_CHILD(ast, node->nd_next));
@@ -289,7 +343,7 @@ dump_array(rb_ast_t *ast, const NODE *node)
     VALUE ary = rb_ary_new();
     rb_ary_push(ary, NEW_CHILD(ast, node->nd_head));
 
-    while (node->nd_next && nd_type(node->nd_next) == NODE_LIST) {
+    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));
     }
@@ -346,7 +400,7 @@ node_children(rb_ast_t *ast, const NODE *node)
       case NODE_WHILE:
       case NODE_UNTIL:
         return rb_ary_push(rb_ary_new_from_node_args(ast, 2, node->nd_cond, node->nd_body),
-                           (node->nd_state ? Qtrue : Qfalse));
+                           RBOOL(node->nd_state));
       case NODE_ITER:
       case NODE_FOR:
         return rb_ary_new_from_node_args(ast, 2, node->nd_iter, node->nd_body);
@@ -375,7 +429,7 @@ node_children(rb_ast_t *ast, const NODE *node)
 
             while (1) {
                 rb_ary_push(ary, NEW_CHILD(ast, node->nd_1st));
-                if (!node->nd_2nd || nd_type(node->nd_2nd) != (int)type)
+                if (!node->nd_2nd || !nd_type_p(node->nd_2nd, type))
                     break;
                 node = node->nd_2nd;
             }
@@ -393,7 +447,6 @@ node_children(rb_ast_t *ast, const NODE *node)
         }
       case NODE_LASGN:
       case NODE_DASGN:
-      case NODE_DASGN_CURR:
       case NODE_IASGN:
       case NODE_CVASGN:
       case NODE_GASGN:
@@ -413,7 +466,7 @@ node_children(rb_ast_t *ast, const NODE *node)
                                     NEW_CHILD(ast, node->nd_args->nd_body));
       case NODE_OP_ASGN2:
         return rb_ary_new_from_args(5, NEW_CHILD(ast, node->nd_recv),
-                                    node->nd_next->nd_aid ? Qtrue : Qfalse,
+                                    RBOOL(node->nd_next->nd_aid),
                                     ID2SYM(node->nd_next->nd_vid),
                                     ID2SYM(node->nd_next->nd_mid),
                                     NEW_CHILD(ast, node->nd_value));
@@ -485,9 +538,15 @@ node_children(rb_ast_t *ast, const NODE *node)
       case NODE_DXSTR:
       case NODE_DREGX:
       case NODE_DSYM:
-        return rb_ary_new_from_args(3, node->nd_lit,
-                                    NEW_CHILD(ast, node->nd_next->nd_head),
-                                    NEW_CHILD(ast, node->nd_next->nd_next));
+        {
+            NODE *n = node->nd_next;
+            VALUE head = Qnil, next = Qnil;
+            if (n) {
+                head = NEW_CHILD(ast, n->nd_head);
+                next = NEW_CHILD(ast, n->nd_next);
+            }
+            return rb_ary_new_from_args(3, node->nd_lit, head, next);
+        }
       case NODE_EVSTR:
         return rb_ary_new_from_node_args(ast, 1, node->nd_body);
       case NODE_ARGSCAT:
@@ -570,11 +629,11 @@ node_children(rb_ast_t *ast, const NODE *node)
         }
       case NODE_SCOPE:
         {
-            ID *tbl = node->nd_tbl;
-            int i, size = tbl ? (int)*tbl++ : 0;
+            rb_ast_id_table_t *tbl = 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[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));
         }
@@ -609,6 +668,8 @@ node_children(rb_ast_t *ast, const NODE *node)
                                         NEW_CHILD(ast, node->nd_pkwargs),
                                         kwrest);
         }
+      case NODE_ERROR:
+        return rb_ary_new_from_node_args(ast, 0);
       case NODE_ARGS_AUX:
       case NODE_LAST:
         break;
@@ -663,6 +724,15 @@ ast_node_last_column(rb_execution_context_t *ec, VALUE self)
 }
 
 static VALUE
+ast_node_all_tokens(rb_execution_context_t *ec, VALUE self)
+{
+    struct ASTNodeData *data;
+    TypedData_Get_Struct(self, struct ASTNodeData, &rb_node_type, data);
+
+    return rb_ast_tokens(data->ast);
+}
+
+static VALUE
 ast_node_inspect(rb_execution_context_t *ec, VALUE self)
 {
     VALUE str;
@@ -682,6 +752,16 @@ ast_node_inspect(rb_execution_context_t *ec, VALUE self)
     return str;
 }
 
+static VALUE
+ast_node_script_lines(rb_execution_context_t *ec, VALUE self)
+{
+    struct ASTNodeData *data;
+    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;
+}
+
 #include "ast.rbinc"
 
 void
diff --git a/ast.rb b/ast.rb
index 34fa645671..f3f72c747f 100644
--- a/ast.rb
+++ b/ast.rb
@@ -1,145 +1,275 @@
 # for ast.c
 
-class RubyVM
+# AbstractSyntaxTree provides methods to parse Ruby code into
+# abstract syntax trees. The nodes in the tree
+# are instances of RubyVM::AbstractSyntaxTree::Node.
+#
+# This module is MRI specific as it exposes implementation details
+# of the MRI abstract syntax tree.
+#
+# This module is experimental and its API is not stable, therefore it might
+# change without notice. As examples, the order of children nodes is not
+# guaranteed, the number of children nodes might change, there is no way to
+# 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.
+#
+module RubyVM::AbstractSyntaxTree
 
-  # AbstractSyntaxTree provides methods to parse Ruby code into
-  # abstract syntax trees. The nodes in the tree
-  # are instances of RubyVM::AbstractSyntaxTree::Node.
+  #  call-seq:
+  #     RubyVM::AbstractSyntaxTree.parse(string, keep_script_lines: false, error_tolerant: false, keep_tokens: false) -> RubyVM::AbstractSyntaxTree::Node
   #
-  # This module is MRI specific as it exposes implementation details
-  # of the MRI abstract syntax tree.
+  #  Parses the given _string_ into an abstract syntax tree,
+  #  returning the root node of that tree.
   #
-  # This module is experimental and its API is not stable, therefore it might
-  # change without notice. As examples, the order of children nodes is not
-  # guaranteed, the number of children nodes might change, there is no way to
-  # access children nodes by name, etc.
+  #    RubyVM::AbstractSyntaxTree.parse("x = 1 + 2")
+  #    # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-1:9>
   #
-  # 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.
+  #  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.
   #
-  module AbstractSyntaxTree
+  #  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 expresion.
+  #
+  def self.parse string, keep_script_lines: false, 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, keep_script_lines: false, 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.
+  #
+  #   SyntaxError is raised if _pathname_'s contents are not
+  #   valid Ruby syntax.
+  #
+  #     RubyVM::AbstractSyntaxTree.parse_file("my-app/app.rb")
+  #     # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-31:3>
+  #
+  #   See ::parse for explanation of keyword argument meaning and usage.
+  def self.parse_file pathname, keep_script_lines: false, 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, keep_script_lines: false, error_tolerant: false, keep_tokens: false)   -> RubyVM::AbstractSyntaxTree::Node
+  #     RubyVM::AbstractSyntaxTree.of(method, keep_script_lines: false, error_tolerant: false, keep_tokens: false) -> RubyVM::AbstractSyntaxTree::Node
+  #
+  #   Returns AST nodes of the given _proc_ or _method_.
+  #
+  #     RubyVM::AbstractSyntaxTree.of(proc {1 + 2})
+  #     # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:35-1:42>
+  #
+  #     def hello
+  #       puts "hello, world"
+  #     end
+  #
+  #     RubyVM::AbstractSyntaxTree.of(method(:hello))
+  #     # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-3:3>
+  #
+  #   See ::parse for explanation of keyword argument meaning and usage.
+  def self.of body, keep_script_lines: false, 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
+  # RubyVM::AbstractSyntaxTree.
+  #
+  # This class is MRI specific.
+  #
+  class Node
 
     #  call-seq:
-    #     RubyVM::AbstractSyntaxTree.parse(string) -> RubyVM::AbstractSyntaxTree::Node
+    #     node.type -> symbol
     #
-    #  Parses the given _string_ into an abstract syntax tree,
-    #  returning the root node of that tree.
+    #  Returns the type of this node as a symbol.
     #
-    #  SyntaxError is raised if the given _string_ is invalid syntax.
+    #    root = RubyVM::AbstractSyntaxTree.parse("x = 1 + 2")
+    #    root.type # => :SCOPE
+    #    lasgn = root.children[2]
+    #    lasgn.type # => :LASGN
+    #    call = lasgn.children[1]
+    #    call.type # => :OPCALL
+    def type
+      Primitive.ast_node_type
+    end
+
+    #  call-seq:
+    #     node.first_lineno -> integer
     #
-    #    RubyVM::AbstractSyntaxTree.parse("x = 1 + 2")
-    #    # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-1:9>
-    def self.parse string
-      Primitive.ast_s_parse string
+    #  The line number in the source code where this AST's text began.
+    def first_lineno
+      Primitive.ast_node_first_lineno
     end
 
     #  call-seq:
-    #     RubyVM::AbstractSyntaxTree.parse_file(pathname) -> RubyVM::AbstractSyntaxTree::Node
+    #     node.first_column -> integer
     #
-    #   Reads the file from _pathname_, then parses it like ::parse,
-    #   returning the root node of the abstract syntax tree.
+    #  The column number in the source code where this AST's text began.
+    def first_column
+      Primitive.ast_node_first_column
+    end
+
+    #  call-seq:
+    #     node.last_lineno -> integer
     #
-    #   SyntaxError is raised if _pathname_'s contents are not
-    #   valid Ruby syntax.
+    #  The line number in the source code where this AST's text ended.
+    def last_lineno
+      Primitive.ast_node_last_lineno
+    end
+
+    #  call-seq:
+    #     node.last_column -> integer
     #
-    #     RubyVM::AbstractSyntaxTree.parse_file("my-app/app.rb")
-    #     # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-31:3>
-    def self.parse_file pathname
-      Primitive.ast_s_parse_file pathname
+    #  The column number in the source code where this AST's text ended.
+    def last_column
+      Primitive.ast_node_last_column
     end
 
     #  call-seq:
-    #     RubyVM::AbstractSyntaxTree.of(proc)   -> RubyVM::AbstractSyntaxTree::Node
-    #     RubyVM::AbstractSyntaxTree.of(method) -> RubyVM::AbstractSyntaxTree::Node
+    #     node.tokens -> array
     #
-    #   Returns AST nodes of the given _proc_ or _method_.
+    #  Returns tokens corresponding to the location of the node.
+    #  Returns +nil+ if +keep_tokens+ is not enabled when #parse method is called.
     #
-    #     RubyVM::AbstractSyntaxTree.of(proc {1 + 2})
-    #     # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:35-1:42>
+    #    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"
     #
-    #     def hello
-    #       puts "hello, world"
-    #     end
+    #  Token is an array of:
     #
-    #     RubyVM::AbstractSyntaxTree.of(method(:hello))
-    #     # => #<RubyVM::AbstractSyntaxTree::Node:SCOPE@1:0-3:3>
-    def self.of body
-      Primitive.ast_s_of body
-    end
+    #  - id
+    #  - token type
+    #  - source code text
+    #  - location [ first_lineno, first_column, last_lineno, last_column ]
+    def tokens
+      return nil unless all_tokens
 
-    # RubyVM::AbstractSyntaxTree::Node instances are created by parse methods in
-    # RubyVM::AbstractSyntaxTree.
-    #
-    # This class is MRI specific.
-    #
-    class Node
-
-      #  call-seq:
-      #     node.type -> symbol
-      #
-      #  Returns the type of this node as a symbol.
-      #
-      #    root = RubyVM::AbstractSyntaxTree.parse("x = 1 + 2")
-      #    root.type # => :SCOPE
-      #    lasgn = root.children[2]
-      #    lasgn.type # => :LASGN
-      #    call = lasgn.children[1]
-      #    call.type # => :OPCALL
-      def type
-        Primitive.ast_node_type
+      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.first_lineno -> integer
-      #
-      #  The line number in the source code where this AST's text began.
-      def first_lineno
-        Primitive.ast_node_first_lineno
-      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.first_column -> integer
-      #
-      #  The column number in the source code where this AST's text began.
-      def first_column
-        Primitive.ast_node_first_column
-      end
+    #  call-seq:
+    #     node.children -> array
+    #
+    #  Returns AST nodes under this one.  Each kind of node
+    #  has different children, depending on what kind of node it is.
+    #
+    #  The returned array may contain other nodes or <code>nil</code>.
+    def children
+      Primitive.ast_node_children
+    end
 
-      #  call-seq:
-      #     node.last_lineno -> integer
-      #
-      #  The line number in the source code where this AST's text ended.
-      def last_lineno
-        Primitive.ast_node_last_lineno
-      end
+    #  call-seq:
+    #     node.inspect -> string
+    #
+    #  Returns debugging information about this node as a string.
+    def inspect
+      Primitive.ast_node_inspect
+    end
 
-      #  call-seq:
-      #     node.last_column -> integer
-      #
-      #  The column number in the source code where this AST's text ended.
-      def last_column
-        Primitive.ast_node_last_column
-      end
+    #  call-seq:
+    #     node.node_id -> integer
+    #
+    #  Returns an internal node_id number.
+    #  Note that this is an API for ruby internal use, debugging,
+    #  and research. Do not use this for any other purpose.
+    #  The compatibility is not guaranteed.
+    def node_id
+      Primitive.ast_node_node_id
+    end
 
-      #  call-seq:
-      #     node.children -> array
-      #
-      #  Returns AST nodes under this one.  Each kind of node
-      #  has different children, depending on what kind of node it is.
-      #
-      #  The returned array may contain other nodes or <code>nil</code>.
-      def children
-        Primitive.ast_node_children
-      end
+    #  call-seq:
+    #     node.script_lines -> array
+    #
+    #  Returns the original source code as an array of lines.
+    #
+    #  Note that this is an API for ruby internal use, debugging,
+    #  and research. Do not use this for any other purpose.
+    #  The compatibility is not guaranteed.
+    def script_lines
+      Primitive.ast_node_script_lines
+    end
 
-      #  call-seq:
-      #     node.inspect -> string
-      #
-      #  Returns debugging information about this node as a string.
-      def inspect
-        Primitive.ast_node_inspect
+    #  call-seq:
+    #     node.source -> string
+    #
+    #  Returns the code fragment that corresponds to this AST.
+    #
+    #  Note that this is an API for ruby internal use, debugging,
+    #  and research. Do not use this for any other purpose.
+    #  The compatibility is not guaranteed.
+    #
+    #  Also note that this API may return an incomplete code fragment
+    #  that does not parse; for example, a here document following
+    #  an expression may be dropped.
+    def source
+      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.join
+      else
+        nil
       end
     end
   end
diff --git a/autogen.sh b/autogen.sh
new file mode 100755
index 0000000000..f8cdf3c0c1
--- /dev/null
+++ b/autogen.sh
@@ -0,0 +1,17 @@
+#!/bin/sh
+
+PWD=
+case "$0" in
+*/*) srcdir=`dirname $0`;;
+*) srcdir="";;
+esac
+
+symlink='--install --symlink'
+case " $* " in
+    *" -i "*|*" --install "*)
+        # reset to copy missing standard auxiliary files, instead of symlinks
+        symlink=
+        ;;
+esac
+
+exec ${AUTORECONF:-autoreconf} ${symlink} "$@" ${srcdir:+"$srcdir"}
diff --git a/basictest/test.rb b/basictest/test.rb
index 52008b78db..95875b52a6 100755
--- a/basictest/test.rb
+++ b/basictest/test.rb
@@ -1960,6 +1960,8 @@ test_ok(p1.call == 5)
 test_ok(i7 == nil)
 end
 
+# WASI doesn't support spawning a new process for now.
+unless /wasi/ =~ RUBY_PLATFORM
 test_check "system"
 test_ok(`echo foobar` == "foobar\n")
 test_ok(`./miniruby -e 'print "foobar"'` == 'foobar')
@@ -2010,6 +2012,7 @@ test_ok(done)
 
 File.unlink script_tmp or `/bin/rm -f "#{script_tmp}"`
 File.unlink "#{script_tmp}.bak" or `/bin/rm -f "#{script_tmp}.bak"`
+end # not /wasi/ =~ RUBY_PLATFORM
 
 test_check "const"
 TEST1 = 1
diff --git a/benchmark/README.md b/benchmark/README.md
index 39a5aa139b..e11381cad9 100644
--- a/benchmark/README.md
+++ b/benchmark/README.md
@@ -28,15 +28,17 @@ See also:
 
 ```console
 Usage: benchmark-driver [options] RUBY|YAML...
-    -r, --runner TYPE                Specify runner type: ips, time, memory, once (default: ips)
-    -o, --output TYPE                Specify output type: compare, simple, markdown, record (default: compare)
+    -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)
     -e, --executables EXECS          Ruby executables (e1::path1 arg1; e2::path2 arg2;...)
         --rbenv VERSIONS             Ruby executables in rbenv (x.x.x arg1;y.y.y arg2;...)
         --repeat-count NUM           Try benchmark NUM times and use the fastest result or the worst memory usage
         --repeat-result TYPE         Yield "best", "average" or "worst" result with --repeat-count (default: best)
+        --alternate                  Alternate executables instead of running the same executable in a row with --repeat-count
         --bundler                    Install and use gems specified in Gemfile
         --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)
 ```
 
diff --git a/benchmark/array_max_float.yml b/benchmark/array_max_float.yml
new file mode 100644
index 0000000000..ace1ae2e14
--- /dev/null
+++ b/benchmark/array_max_float.yml
@@ -0,0 +1,30 @@
+prelude: |
+  ary2 = 2.times.map(&:to_f).shuffle
+  ary10 = 10.times.map(&:to_f).shuffle
+  ary100 = 100.times.map(&:to_f).shuffle
+  ary500 = 500.times.map(&:to_f).shuffle
+  ary1000 = 1000.times.map(&:to_f).shuffle
+  ary2000 = 2500.times.map(&:to_f).shuffle
+  ary3000 = 2500.times.map(&:to_f).shuffle
+  ary5000 = 5000.times.map(&:to_f).shuffle
+  ary10000 = 10000.times.map(&:to_f).shuffle
+  ary20000 = 20000.times.map(&:to_f).shuffle
+  ary50000 = 50000.times.map(&:to_f).shuffle
+  ary100000 = 100000.times.map(&:to_f).shuffle
+
+benchmark:
+  ary2.max: ary2.max
+  ary10.max: ary10.max
+  ary100.max: ary100.max
+  ary500.max: ary500.max
+  ary1000.max: ary1000.max
+  ary2000.max: ary2000.max
+  ary3000.max: ary3000.max
+  ary5000.max: ary5000.max
+  ary10000.max: ary10000.max
+  ary20000.max: ary20000.max
+  ary50000.max: ary50000.max
+  ary100000.max: ary100000.max
+
+loop_count: 10000
+
diff --git a/benchmark/array_max_int.yml b/benchmark/array_max_int.yml
new file mode 100644
index 0000000000..acd83684d0
--- /dev/null
+++ b/benchmark/array_max_int.yml
@@ -0,0 +1,31 @@
+prelude: |
+  ary2 = 2.times.to_a.shuffle
+  ary10 = 10.times.to_a.shuffle
+  ary100 = 100.times.to_a.shuffle
+  ary500 = 500.times.to_a.shuffle
+  ary1000 = 1000.times.to_a.shuffle
+  ary2000 = 2500.times.to_a.shuffle
+  ary3000 = 2500.times.to_a.shuffle
+  ary5000 = 5000.times.to_a.shuffle
+  ary10000 = 10000.times.to_a.shuffle
+  ary20000 = 20000.times.to_a.shuffle
+  ary50000 = 50000.times.to_a.shuffle
+  ary100000 = 100000.times.to_a.shuffle
+  ary1000000 = 1000000.times.to_a.shuffle
+
+benchmark:
+  ary2.max: ary2.max
+  ary10.max: ary10.max
+  ary100.max: ary100.max
+  ary500.max: ary500.max
+  ary1000.max: ary1000.max
+  ary2000.max: ary2000.max
+  ary3000.max: ary3000.max
+  ary5000.max: ary5000.max
+  ary10000.max: ary10000.max
+  ary20000.max: ary20000.max
+  ary50000.max: ary50000.max
+  ary100000.max: ary100000.max
+  ary1000000.max: ary1000000.max
+
+loop_count: 10000
diff --git a/benchmark/array_max_str.yml b/benchmark/array_max_str.yml
new file mode 100644
index 0000000000..2aeed010f2
--- /dev/null
+++ b/benchmark/array_max_str.yml
@@ -0,0 +1,30 @@
+prelude: |
+  ary2 = 2.times.map(&:to_s).shuffle
+  ary10 = 10.times.map(&:to_s).shuffle
+  ary100 = 100.times.map(&:to_s).shuffle
+  ary500 = 500.times.map(&:to_s).shuffle
+  ary1000 = 1000.times.map(&:to_s).shuffle
+  ary2000 = 2500.times.map(&:to_s).shuffle
+  ary3000 = 2500.times.map(&:to_s).shuffle
+  ary5000 = 5000.times.map(&:to_s).shuffle
+  ary10000 = 10000.times.map(&:to_s).shuffle
+  ary20000 = 20000.times.map(&:to_s).shuffle
+  ary50000 = 50000.times.map(&:to_s).shuffle
+  ary100000 = 100000.times.map(&:to_s).shuffle
+
+benchmark:
+  ary2.max: ary2.max
+  ary10.max: ary10.max
+  ary100.max: ary100.max
+  ary500.max: ary500.max
+  ary1000.max: ary1000.max
+  ary2000.max: ary2000.max
+  ary3000.max: ary3000.max
+  ary5000.max: ary5000.max
+  ary10000.max: ary10000.max
+  ary20000.max: ary20000.max
+  ary50000.max: ary50000.max
+  ary100000.max: ary100000.max
+
+loop_count: 10000
+
diff --git a/benchmark/array_min.yml b/benchmark/array_min.yml
new file mode 100644
index 0000000000..53e5072b14
--- /dev/null
+++ b/benchmark/array_min.yml
@@ -0,0 +1,31 @@
+prelude: |
+  ary2 = 2.times.to_a.shuffle
+  ary10 = 10.times.to_a.shuffle
+  ary100 = 100.times.to_a.shuffle
+  ary500 = 500.times.to_a.shuffle
+  ary1000 = 1000.times.to_a.shuffle
+  ary2000 = 2500.times.to_a.shuffle
+  ary3000 = 2500.times.to_a.shuffle
+  ary5000 = 5000.times.to_a.shuffle
+  ary10000 = 10000.times.to_a.shuffle
+  ary20000 = 20000.times.to_a.shuffle
+  ary50000 = 50000.times.to_a.shuffle
+  ary100000 = 100000.times.to_a.shuffle
+  ary1000000 = 1000000.times.to_a.shuffle
+
+benchmark:
+  ary2.min: ary2.min
+  ary10.min: ary10.min
+  ary100.min: ary100.min
+  ary500.min: ary500.min
+  ary1000.min: ary1000.min
+  ary2000.min: ary2000.min
+  ary3000.min: ary3000.min
+  ary5000.min: ary5000.min
+  ary10000.min: ary10000.min
+  ary20000.min: ary20000.min
+  ary50000.min: ary50000.min
+  ary100000.min: ary100000.min
+  ary1000000.min: ary1000000.min
+
+loop_count: 10000
diff --git a/benchmark/array_sample.yml b/benchmark/array_sample.yml
new file mode 100644
index 0000000000..1cd2b34794
--- /dev/null
+++ b/benchmark/array_sample.yml
@@ -0,0 +1,4 @@
+prelude: ary = (1..10_000).to_a
+benchmark:
+  - ary.sample
+  - ary.sample(2)
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/attr_accessor.yml b/benchmark/attr_accessor.yml
new file mode 100644
index 0000000000..82134cdf9b
--- /dev/null
+++ b/benchmark/attr_accessor.yml
@@ -0,0 +1,29 @@
+prelude: |
+  class C
+    attr_accessor :x
+    def initialize
+      @x = nil
+    end
+    class_eval <<-END
+      def ar
+        #{'x;'*256}
+      end
+      def aw
+        #{'self.x = nil;'*256}
+      end
+      def arm
+        m = method(:x)
+        #{'m.call;'*256}
+      end
+      def awm
+        m = method(:x=)
+        #{'m.call(nil);'*256}
+      end
+    END
+  end
+  obj = C.new
+benchmark:
+  attr_reader: "obj.ar"
+  attr_writer: "obj.aw"
+  attr_reader_method: "obj.arm"
+  attr_writer_method: "obj.awm"
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
new file mode 100644
index 0000000000..9e1f99d64e
--- /dev/null
+++ b/benchmark/buffer_get.yml
@@ -0,0 +1,25 @@
+prelude: |
+  # frozen_string_literal: true
+  Warning[:experimental] = false
+  string = "The quick brown fox jumped over the lazy dog."
+  buffer = IO::Buffer.for(string)
+  format = [:U32, :U32, :U32, :U32]
+benchmark:
+  string.unpack1: |
+    [
+      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/constant_invalidation.rb b/benchmark/constant_invalidation.rb
new file mode 100644
index 0000000000..a95ec6f37e
--- /dev/null
+++ b/benchmark/constant_invalidation.rb
@@ -0,0 +1,22 @@
+$VERBOSE = nil
+
+CONSTANT1 = 1
+CONSTANT2 = 1
+CONSTANT3 = 1
+CONSTANT4 = 1
+CONSTANT5 = 1
+
+def constants
+  [CONSTANT1, CONSTANT2, CONSTANT3, CONSTANT4, CONSTANT5]
+end
+
+500_000.times do
+  constants
+
+  # With previous behavior, this would cause all of the constant caches
+  # associated with the constant lookups listed above to invalidate, meaning
+  # they would all have to be fetched again. With current behavior, it only
+  # invalidates when a name matches, so the following constant set shouldn't
+  # impact the constant lookups listed above.
+  INVALIDATE = true
+end
diff --git a/benchmark/enum_lazy_flat_map.yml b/benchmark/enum_lazy_flat_map.yml
new file mode 100644
index 0000000000..0ee390a441
--- /dev/null
+++ b/benchmark/enum_lazy_flat_map.yml
@@ -0,0 +1,16 @@
+prelude: |
+  num = (1..).lazy.take(100)
+  ary2 = [[1,2]].cycle.lazy.take(10)
+  ary10 = [[*1..10]].cycle.lazy.take(10)
+  ary20 = [[*1..20]].cycle.lazy.take(10)
+  ary50 = [[*1..50]].cycle.lazy.take(10)
+  ary100 = [[*1..100]].cycle.lazy.take(10)
+
+benchmark:
+  num3: num.flat_map {|x| x}.take(3).to_a
+  num10: num.flat_map {|x| x}.take(3).to_a
+  ary2:  ary2.flat_map {|x| x}.take(3).to_a
+  ary10: ary10.flat_map {|x| x}.take(3).to_a
+  ary20: ary20.flat_map {|x| x}.take(3).to_a
+  ary50: ary50.flat_map {|x| x}.take(3).to_a
+  ary100: ary100.flat_map {|x| x}.take(3).to_a
diff --git a/benchmark/enum_lazy_zip.yml b/benchmark/enum_lazy_zip.yml
new file mode 100644
index 0000000000..4566ff0261
--- /dev/null
+++ b/benchmark/enum_lazy_zip.yml
@@ -0,0 +1,22 @@
+prelude: |
+  a = (1..3).lazy
+  b = a.map {|x| x}
+
+benchmark:
+  first_ary: a.zip(["a", "b", "c"]).first
+  first_nonary: a.zip("a".."c").first
+  first_noarg: a.zip.first
+
+  take3_ary: a.zip(["a", "b", "c"]).take(3).force
+  take3_nonary: a.zip("a".."c").take(3).force
+  take3_noarg: a.zip.take(3).force
+
+  chain-first_ary: b.zip(["a", "b", "c"]).first
+  chain-first_nonary: b.zip("a".."c").first
+  chain-first_noarg: b.zip.first
+
+  chain-take3_ary: b.zip(["a", "b", "c"]).take(3).force
+  chain-take3_nonary: b.zip("a".."c").take(3).force
+  chain-take3_noarg: b.zip.take(3).force
+
+  block: a.zip("a".."c") {|x, y| [x, y]}
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_tally.yml b/benchmark/enum_tally.yml
new file mode 100644
index 0000000000..edd2e040a0
--- /dev/null
+++ b/benchmark/enum_tally.yml
@@ -0,0 +1,4 @@
+prelude: |
+  list = ("aaa".."zzz").to_a*10
+benchmark:
+  tally: list.tally
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/float_methods.yml b/benchmark/float_methods.yml
new file mode 100644
index 0000000000..56ea41effc
--- /dev/null
+++ b/benchmark/float_methods.yml
@@ -0,0 +1,14 @@
+prelude: |
+  flo = 4.2
+benchmark:
+  to_f: |
+    flo.to_f
+  abs: |
+    flo.abs
+  magnitude: |
+    flo.magnitude
+  -@: |
+    -flo
+  zero?: |
+    flo.zero?
+loop_count: 20000000
diff --git a/benchmark/float_neg_posi.yml b/benchmark/float_neg_posi.yml
new file mode 100644
index 0000000000..172db1bf6d
--- /dev/null
+++ b/benchmark/float_neg_posi.yml
@@ -0,0 +1,8 @@
+prelude: |
+  flo = 4.2
+benchmark:
+  negative?: |
+    flo.negative?
+  positive?: |
+    flo.positive?
+loop_count: 20000000
diff --git a/benchmark/float_to_s.yml b/benchmark/float_to_s.yml
new file mode 100644
index 0000000000..0abae5cdb8
--- /dev/null
+++ b/benchmark/float_to_s.yml
@@ -0,0 +1,7 @@
+prelude: |
+  floats = [*0.0.step(1.0, 0.0001)]
+
+benchmark:
+  to_s: floats.each {|f| f.to_s}
+
+loop_count: 1000
diff --git a/benchmark/hash_aref_array.rb b/benchmark/hash_aref_array.rb
new file mode 100644
index 0000000000..ac7a683d95
--- /dev/null
+++ b/benchmark/hash_aref_array.rb
@@ -0,0 +1,5 @@
+h = {}
+arrays = (0..99).each_slice(10).to_a
+#STDERR.puts arrays.inspect
+arrays.each { |s| h[s] = s }
+200_000.times { arrays.each { |s| h[s] } }
diff --git a/benchmark/hash_first.yml b/benchmark/hash_first.yml
new file mode 100644
index 0000000000..c26df1a7ed
--- /dev/null
+++ b/benchmark/hash_first.yml
@@ -0,0 +1,11 @@
+prelude: |
+  hash1 = 1_000_000.times.to_h { [rand, true]}
+  hash2 = hash1.dup
+  hash2.keys[1..100_000].each { hash2.delete _1 }
+  hash2.delete hash2.first[0]
+
+benchmark:
+  hash1: hash1.first
+  hash2: hash2.first
+
+loop_count: 100_000
diff --git a/benchmark/io_write.rb b/benchmark/io_write.rb
new file mode 100644
index 0000000000..cdb409948b
--- /dev/null
+++ b/benchmark/io_write.rb
@@ -0,0 +1,22 @@
+#!/usr/bin/env ruby
+
+require 'benchmark'
+
+i, o = IO.pipe
+o.sync = true
+
+DOT = ".".freeze
+
+chunks = 100_000.times.collect{DOT}
+
+thread = Thread.new do
+  while i.read(1024)
+  end
+end
+
+100.times do
+  o.write(*chunks)
+end
+
+o.close
+thread.join
diff --git a/benchmark/iseq_load_from_binary.yml b/benchmark/iseq_load_from_binary.yml
new file mode 100644
index 0000000000..7e9d73bdd4
--- /dev/null
+++ b/benchmark/iseq_load_from_binary.yml
@@ -0,0 +1,25 @@
+prelude: |
+  symbol = RubyVM::InstructionSequence.compile(":foo; :bar; :baz; :egg; :spam").to_binary
+
+  define_method = RubyVM::InstructionSequence.compile(%{
+    def foo; end
+    def bar; end
+    def baz; end
+    def egg; end
+    def spam; end
+  }).to_binary
+
+  all = RubyVM::InstructionSequence.compile(%{
+    module Foo; def foo; :foo; end; end
+    module Bar; def bar; :bar; end; end
+    module Baz; def baz; :baz; end; end
+    class Egg; def egg; :egg; end; end
+    class Spaml; def spam; :spam; end; end
+  }).to_binary
+
+benchmark:
+  symbol: RubyVM::InstructionSequence.load_from_binary(symbol)
+  define_method: RubyVM::InstructionSequence.load_from_binary(define_method)
+  all: RubyVM::InstructionSequence.load_from_binary(all)
+
+loop_count: 100_000
diff --git a/benchmark/ivar_extend.yml b/benchmark/ivar_extend.yml
new file mode 100644
index 0000000000..eb9ee923f5
--- /dev/null
+++ b/benchmark/ivar_extend.yml
@@ -0,0 +1,23 @@
+prelude: |
+  class Embedded
+    def initialize
+      @a = 1
+      @b = 1
+      @c = 1
+    end
+  end
+
+  class Extended
+    def initialize
+      @a = 1
+      @b = 1
+      @c = 1
+      @d = 1
+      @e = 1
+      @f = 1
+    end
+  end
+benchmark:
+  embedded: Embedded.new
+  extended: Extended.new
+loop_count: 20_000_000
diff --git a/benchmark/lib/benchmark_driver/runner/mjit.rb b/benchmark/lib/benchmark_driver/runner/mjit.rb
index 1d4693e8be..3a58a620de 100644
--- a/benchmark/lib/benchmark_driver/runner/mjit.rb
+++ b/benchmark/lib/benchmark_driver/runner/mjit.rb
@@ -16,7 +16,7 @@ class BenchmarkDriver::Runner::Mjit < BenchmarkDriver::Runner::Ips
         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
+            while __bmdv_ruby_i < 10000 # MJIT call threshold
               #{job.script}
               __bmdv_ruby_i += 1
             end
diff --git a/benchmark/lib/benchmark_driver/runner/mjit_exec.rb b/benchmark/lib/benchmark_driver/runner/mjit_exec.rb
deleted file mode 100644
index 9f7c8c8af3..0000000000
--- a/benchmark/lib/benchmark_driver/runner/mjit_exec.rb
+++ /dev/null
@@ -1,237 +0,0 @@
-require 'benchmark_driver/struct'
-require 'benchmark_driver/metric'
-require 'erb'
-
-# A special runner dedicated for measuring mjit_exec overhead.
-class BenchmarkDriver::Runner::MjitExec
-  METRIC = BenchmarkDriver::Metric.new(name: 'Iteration per second', unit: 'i/s')
-
-  # JobParser returns this, `BenchmarkDriver::Runner.runner_for` searches "*::Job"
-  Job = ::BenchmarkDriver::Struct.new(
-    :name,        # @param [String] name - This is mandatory for all runner
-    :metrics,     # @param [Array<BenchmarkDriver::Metric>]
-    :num_methods, # @param [Integer] num_methods - The number of methods to be defined
-    :loop_count,  # @param [Integer] loop_count
-    :from_jit,    # @param [TrueClass,FalseClass] from_jit - Whether the mjit_exec() is from JIT or not
-    :to_jit,      # @param [TrueClass,FalseClass] to_jit - Whether the mjit_exec() is to JIT or not
-  )
-  # Dynamically fetched and used by `BenchmarkDriver::JobParser.parse`
-  class << JobParser = Module.new
-    # @param [Array,String] num_methods
-    # @param [Integer] loop_count
-    # @param [TrueClass,FalseClass] from_jit
-    # @param [TrueClass,FalseClass] to_jit
-    def parse(num_methods:, loop_count:, from_jit:, to_jit:)
-      if num_methods.is_a?(String)
-        num_methods = eval(num_methods)
-      end
-
-      num_methods.map do |num|
-        if num_methods.size > 1
-          suffix = "[#{'%4d' % num}]"
-        else
-          suffix = "_#{num}"
-        end
-        Job.new(
-          name: "mjit_exec_#{from_jit ? 'JT' : 'VM'}2#{to_jit ? 'JT' : 'VM'}#{suffix}",
-          metrics: [METRIC],
-          num_methods: num,
-          loop_count: loop_count,
-          from_jit: from_jit,
-          to_jit: to_jit,
-        )
-      end
-    end
-  end
-
-  # @param [BenchmarkDriver::Config::RunnerConfig] config
-  # @param [BenchmarkDriver::Output] output
-  # @param [BenchmarkDriver::Context] contexts
-  def initialize(config:, output:, contexts:)
-    @config = config
-    @output = output
-    @contexts = contexts
-  end
-
-  # This method is dynamically called by `BenchmarkDriver::JobRunner.run`
-  # @param [Array<BenchmarkDriver::Runner::Peak::Job>] jobs
-  def run(jobs)
-    @output.with_benchmark do
-      jobs.each do |job|
-        @output.with_job(name: job.name) do
-          @contexts.each do |context|
-            result = BenchmarkDriver::Repeater.with_repeat(config: @config, larger_better: true, rest_on_average: :average) do
-              run_benchmark(job, context: context)
-            end
-            value, duration = result.value
-            @output.with_context(name: context.name, executable: context.executable, gems: context.gems, prelude: context.prelude) do
-              @output.report(values: { METRIC => value }, duration: duration, loop_count: job.loop_count)
-            end
-          end
-        end
-      end
-    end
-  end
-
-  private
-
-  # @param [BenchmarkDriver::Runner::Ips::Job] job - loop_count is not nil
-  # @param [BenchmarkDriver::Context] context
-  # @return [BenchmarkDriver::Metrics]
-  def run_benchmark(job, context:)
-    if job.from_jit
-      if job.to_jit
-        benchmark = BenchmarkJT2JT.new(num_methods: job.num_methods, loop_count: job.loop_count)
-      else
-        raise NotImplementedError, "JT2VM is not implemented yet"
-      end
-    else
-      if job.to_jit
-        benchmark = BenchmarkVM2JT.new(num_methods: job.num_methods, loop_count: job.loop_count)
-      else
-        benchmark = BenchmarkVM2VM.new(num_methods: job.num_methods, loop_count: job.loop_count)
-      end
-    end
-
-    duration = Tempfile.open(['benchmark_driver-result', '.txt']) do |f|
-      with_script(benchmark.render(result: f.path)) do |path|
-        opt = []
-        if context.executable.command.any? { |c| c.start_with?('--jit') }
-          opt << '--jit-min-calls=2'
-        end
-        IO.popen([*context.executable.command, '--disable-gems', *opt, path], &:read)
-        if $?.success?
-          Float(f.read)
-        else
-          BenchmarkDriver::Result::ERROR
-        end
-      end
-    end
-
-    [job.loop_count.to_f / duration, duration]
-  end
-
-  def with_script(script)
-    if @config.verbose >= 2
-      sep = '-' * 30
-      $stdout.puts "\n\n#{sep}[Script begin]#{sep}\n#{script}#{sep}[Script end]#{sep}\n\n"
-    end
-
-    Tempfile.open(['benchmark_driver-', '.rb']) do |f|
-      f.puts script
-      f.close
-      return yield(f.path)
-    end
-  end
-
-  # @param [Integer] num_methods
-  # @param [Integer] loop_count
-  BenchmarkVM2VM = ::BenchmarkDriver::Struct.new(:num_methods, :loop_count) do
-    # @param [String] result - A file to write result
-    def render(result:)
-      ERB.new(<<~EOS, trim_mode: '%').result(binding)
-        % num_methods.times do |i|
-        def a<%= i %>
-          nil
-        end
-        % end
-        RubyVM::MJIT.pause if RubyVM::MJIT.enabled?
-
-        def vm
-          t = Process.clock_gettime(Process::CLOCK_MONOTONIC)
-          i = 0
-          while i < <%= loop_count / 1000 %>
-        % 1000.times do |i|
-            a<%= i % num_methods %>
-        % end
-            i += 1
-          end
-        % (loop_count % 1000).times do |i|
-          a<%= i % num_methods %>
-        % end
-          Process.clock_gettime(Process::CLOCK_MONOTONIC) - t
-        end
-
-        vm # warmup call cache
-        File.write(<%= result.dump %>, vm)
-      EOS
-    end
-  end
-  private_constant :BenchmarkVM2VM
-
-  # @param [Integer] num_methods
-  # @param [Integer] loop_count
-  BenchmarkVM2JT = ::BenchmarkDriver::Struct.new(:num_methods, :loop_count) do
-    # @param [String] result - A file to write result
-    def render(result:)
-      ERB.new(<<~EOS, trim_mode: '%').result(binding)
-        % num_methods.times do |i|
-        def a<%= i %>
-          nil
-        end
-        a<%= i %>
-        a<%= i %> # --jit-min-calls=2
-        % end
-        RubyVM::MJIT.pause if RubyVM::MJIT.enabled?
-
-        def vm
-          t = Process.clock_gettime(Process::CLOCK_MONOTONIC)
-          i = 0
-          while i < <%= loop_count / 1000 %>
-        % 1000.times do |i|
-            a<%= i % num_methods %>
-        % end
-            i += 1
-          end
-        % (loop_count % 1000).times do |i|
-          a<%= i % num_methods %>
-        % end
-          Process.clock_gettime(Process::CLOCK_MONOTONIC) - t
-        end
-
-        vm # warmup call cache
-        File.write(<%= result.dump %>, vm)
-      EOS
-    end
-  end
-  private_constant :BenchmarkVM2JT
-
-  # @param [Integer] num_methods
-  # @param [Integer] loop_count
-  BenchmarkJT2JT = ::BenchmarkDriver::Struct.new(:num_methods, :loop_count) do
-    # @param [String] result - A file to write result
-    def render(result:)
-      ERB.new(<<~EOS, trim_mode: '%').result(binding)
-        % num_methods.times do |i|
-        def a<%= i %>
-          nil
-        end
-        % end
-
-        # You may need to:
-        #   * Increase `JIT_ISEQ_SIZE_THRESHOLD` to 10000000 in mjit.h
-        #   * Always return false in `inlinable_iseq_p()` of mjit_compile.c
-        def jit
-          t = Process.clock_gettime(Process::CLOCK_MONOTONIC)
-          i = 0
-          while i < <%= loop_count / 1000 %>
-        % 1000.times do |i|
-            a<%= i % num_methods %>
-        % end
-            i += 1
-          end
-        % (loop_count % 1000).times do |i|
-          a<%= i % num_methods %>
-        % end
-          Process.clock_gettime(Process::CLOCK_MONOTONIC) - t
-        end
-
-        jit
-        jit
-        RubyVM::MJIT.pause if RubyVM::MJIT.enabled?
-        File.write(<%= result.dump %>, jit)
-      EOS
-    end
-  end
-  private_constant :BenchmarkJT2JT
-end
diff --git a/benchmark/lib/benchmark_driver/runner/ractor.rb b/benchmark/lib/benchmark_driver/runner/ractor.rb
new file mode 100644
index 0000000000..c730b8e4a5
--- /dev/null
+++ b/benchmark/lib/benchmark_driver/runner/ractor.rb
@@ -0,0 +1,122 @@
+require 'erb'
+
+# A runner to measure performance *inside* Ractor
+class BenchmarkDriver::Runner::Ractor < BenchmarkDriver::Runner::Ips
+  # JobParser returns this, `BenchmarkDriver::Runner.runner_for` searches "*::Job"
+  Job = Class.new(BenchmarkDriver::DefaultJob) do
+    attr_accessor :ractor
+  end
+
+  # Dynamically fetched and used by `BenchmarkDriver::JobParser.parse`
+  JobParser = BenchmarkDriver::DefaultJobParser.for(klass: Job, metrics: [METRIC]).extend(Module.new{
+    def parse(ractor: 1, **kwargs)
+      super(**kwargs).each do |job|
+        job.ractor = ractor
+      end
+    end
+  })
+
+  private
+
+  unless private_instance_methods.include?(:run_benchmark)
+    raise "#run_benchmark is no longer defined in BenchmarkDriver::Runner::Ips"
+  end
+
+  # @param [BenchmarkDriver::Runner::Ips::Job] job - loop_count is not nil
+  # @param [BenchmarkDriver::Context] context
+  # @return [BenchmarkDriver::Metrics]
+  def run_benchmark(job, context:)
+    benchmark = BenchmarkScript.new(
+      preludes:   [context.prelude, job.prelude],
+      script:     job.script,
+      teardown:   job.teardown,
+      loop_count: job.loop_count,
+    )
+
+    results = job.ractor.times.map do
+      Tempfile.open('benchmark_driver_result')
+    end
+    duration = with_script(benchmark.render(results: results.map(&:path))) do |path|
+      success = execute(*context.executable.command, path, exception: false)
+      if success && ((value = results.map { |f| Float(f.read) }.max) > 0)
+        value
+      else
+        BenchmarkDriver::Result::ERROR
+      end
+    end
+    results.each(&:close)
+
+    value_duration(
+      loop_count: job.loop_count,
+      duration: duration,
+    )
+  end
+
+  # @param [String] prelude
+  # @param [String] script
+  # @param [String] teardown
+  # @param [Integer] loop_count
+  BenchmarkScript = ::BenchmarkDriver::Struct.new(:preludes, :script, :teardown, :loop_count) do
+    # @param [String] result - A file to write result
+    def render(results:)
+      prelude = preludes.reject(&:nil?).reject(&:empty?).join("\n")
+      ERB.new(<<-RUBY).result_with_hash(results: results)
+Warning[:experimental] = false
+# shareable-constant-value: experimental_everything
+#{prelude}
+
+if #{loop_count} == 1
+  __bmdv_loop_before = 0
+  __bmdv_loop_after = 0
+else
+  __bmdv_loop_before = Time.new
+  #{while_loop('', loop_count, id: 0)}
+  __bmdv_loop_after = Time.new
+end
+
+__bmdv_ractors = []
+<% results.size.times do %>
+__bmdv_ractors << Ractor.new(__bmdv_loop_after - __bmdv_loop_before) { |__bmdv_loop_time|
+  __bmdv_time = Time
+  __bmdv_script_before = __bmdv_time.new
+  #{while_loop(script, loop_count, id: 1)}
+  __bmdv_script_after = __bmdv_time.new
+
+  (__bmdv_script_after - __bmdv_script_before) - __bmdv_loop_time
+}
+<% end %>
+
+# Wait for all Ractors before executing code to write results
+__bmdv_ractors.map!(&:take)
+
+<% results.each do |result| %>
+File.write(<%= result.dump %>, __bmdv_ractors.shift)
+<% end %>
+
+#{teardown}
+      RUBY
+    end
+
+    private
+
+    # id is to prevent:
+    # can not isolate a Proc because it accesses outer variables (__bmdv_i)
+    def while_loop(content, times, id:)
+      if !times.is_a?(Integer) || times <= 0
+        raise ArgumentError.new("Unexpected times: #{times.inspect}")
+      elsif times == 1
+        return content
+      end
+
+      # TODO: execute in batch
+      <<-RUBY
+__bmdv_i#{id} = 0
+while __bmdv_i#{id} < #{times}
+  #{content}
+  __bmdv_i#{id} += 1
+end
+      RUBY
+    end
+  end
+  private_constant :BenchmarkScript
+end
diff --git a/benchmark/marshal_dump_load_integer.yml b/benchmark/marshal_dump_load_integer.yml
new file mode 100644
index 0000000000..78ebf823d2
--- /dev/null
+++ b/benchmark/marshal_dump_load_integer.yml
@@ -0,0 +1,22 @@
+prelude: |
+  smallint_array = 1000.times.map { |x| x }
+  bigint32_array = 1000.times.map { |x| x + 2**32 }
+  bigint64_array = 1000.times.map { |x| x + 2**64 }
+
+  smallint_dump = Marshal.dump(smallint_array)
+  bigint32_dump = Marshal.dump(bigint32_array)
+  bigint64_dump = Marshal.dump(bigint64_array)
+benchmark:
+  marshal_dump_integer_small: |
+    Marshal.dump(smallint_array)
+  marshal_dump_integer_over_32_bit: |
+    Marshal.dump(bigint32_array)
+  marshal_dump_integer_over_64_bit: |
+    Marshal.dump(bigint64_array)
+  marshal_load_integer_small: |
+    Marshal.load(smallint_dump)
+  marshal_load_integer_over_32_bit: |
+    Marshal.load(bigint32_dump)
+  marshal_load_integer_over_64_bit: |
+    Marshal.load(bigint64_dump)
+loop_count: 4000
diff --git a/benchmark/masgn.yml b/benchmark/masgn.yml
new file mode 100644
index 0000000000..31cb8ee4a3
--- /dev/null
+++ b/benchmark/masgn.yml
@@ -0,0 +1,53 @@
+prelude: |
+  a = [nil] * 3
+  b = Class.new{attr_writer :a, :b, :c}.new
+  c = d = e = f = g = h = i = nil
+benchmark:
+  array2_2: "c = (a[0], a[1] = 1, 2)"
+  array2_3: "c = (a[0], a[1] = 1, 2, 3)"
+  array3_2: "c = (a[0], a[1], a[2] = 1, 2)"
+  array3_3: "c = (a[0], a[1], a[2] = 1, 2, 3)"
+  attr2_2: "c = (b.a, b.b = 1, 2)"
+  attr2_3: "c = (b.a, b.b = 1, 2, 3)"
+  attr3_2: "c = (b.a, b.b, b.c = 1, 2)"
+  attr3_3: "c = (b.a, b.b, b.c = 1, 2, 3)"
+  lvar2_2: "c = (d, e = 1, 2)"
+  lvar2_3: "c = (d, e = 1, 2, 3)"
+  lvar3_2: "c = (d, e, f = 1, 2)"
+  lvar3_3: "c = (d, e, f = 1, 2, 3)"
+  array2_2p: "(a[0], a[1] = 1, 2; nil)"
+  array2_3p: "(a[0], a[1] = 1, 2, 3; nil)"
+  array3_2p: "(a[0], a[1], a[2] = 1, 2; nil)"
+  array3_3p: "(a[0], a[1], a[2] = 1, 2, 3; nil)"
+  attr2_2p: "(b.a, b.b = 1, 2; nil)"
+  attr2_3p: "(b.a, b.b = 1, 2, 3; nil)"
+  attr3_2p: "(b.a, b.b, b.c = 1, 2; nil)"
+  attr3_3p: "(b.a, b.b, b.c = 1, 2, 3; nil)"
+  lvar2_2p: "(d, e = 1, 2; nil)"
+  lvar2_3p: "(d, e = 1, 2, 3; nil)"
+  lvar3_2p: "(d, e, f = 1, 2; nil)"
+  lvar3_3p: "(d, e, f = 1, 2, 3; nil)"
+  array2_2lv: "c = (a[0], a[1] = g, h)"
+  array2_ilv: "c = (a[0], a[1] = g, h, i)"
+  arrayi_2lv: "c = (a[0], a[1], a[2] = g, h)"
+  arrayi_ilv: "c = (a[0], a[1], a[2] = g, h, i)"
+  attr2_2lv: "c = (b.a, b.b = g, h)"
+  attr2_ilv: "c = (b.a, b.b = g, h, i)"
+  attri_2lv: "c = (b.a, b.b, b.c = g, h)"
+  attri_ilv: "c = (b.a, b.b, b.c = g, h, i)"
+  lvar2_2lv: "c = (d, e = g, h)"
+  lvar2_ilv: "c = (d, e = g, h, i)"
+  lvari_2lv: "c = (d, e, f = g, h)"
+  lvari_ilv: "c = (d, e, f = g, h, i)"
+  array2_2plv: "(a[0], a[1] = g, h; nil)"
+  array2_iplv: "(a[0], a[1] = g, h, i; nil)"
+  arrayi_2plv: "(a[0], a[1], a[2] = g, h; nil)"
+  arrayi_iplv: "(a[0], a[1], a[2] = g, h, i; nil)"
+  attr2_2plv: "(b.a, b.b = g, h; nil)"
+  attr2_iplv: "(b.a, b.b = g, h, i; nil)"
+  attri_2plv: "(b.a, b.b, b.c = g, h; nil)"
+  attri_iplv: "(b.a, b.b, b.c = g, h, i; nil)"
+  lvar2_2plv: "(d, e = g, h; nil)"
+  lvar2_iplv: "(d, e = g, h, i; nil)"
+  lvari_2plv: "(d, e, f = g, h; nil)"
+  lvari_iplv: "(d, e, f = g, h, i; nil)"
diff --git a/benchmark/method_bind_call.yml b/benchmark/method_bind_call.yml
new file mode 100644
index 0000000000..9e0e046ed4
--- /dev/null
+++ b/benchmark/method_bind_call.yml
@@ -0,0 +1,16 @@
+prelude: |
+  named_module = Kernel
+
+  module FakeName
+    def self.name
+      "NotMyame".freeze
+    end
+  end
+
+  MOD_NAME = Module.instance_method(:name)
+
+benchmark:
+  fastpath: MOD_NAME.bind_call(Kernel)
+  slowpath: MOD_NAME.bind_call(FakeName)
+
+loop_count: 100_000
diff --git a/benchmark/mjit_exec_jt2jt.yml b/benchmark/mjit_exec_jt2jt.yml
deleted file mode 100644
index 6c303c7a44..0000000000
--- a/benchmark/mjit_exec_jt2jt.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-type: lib/benchmark_driver/runner/mjit_exec
-num_methods: [1]
-#num_methods: (1..100).to_a + [200, 300, 400, 500, 600, 700, 800, 900, 1000]
-loop_count: 50000000
-from_jit: true
-to_jit: true
diff --git a/benchmark/mjit_exec_vm2jt.yml b/benchmark/mjit_exec_vm2jt.yml
deleted file mode 100644
index 764883f070..0000000000
--- a/benchmark/mjit_exec_vm2jt.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-type: lib/benchmark_driver/runner/mjit_exec
-num_methods: [1]
-#num_methods: (1..100).to_a + [200, 300, 400, 500, 600, 700, 800, 900, 1000]
-loop_count: 50000000
-from_jit: false
-to_jit: true
diff --git a/benchmark/mjit_exec_vm2vm.yml b/benchmark/mjit_exec_vm2vm.yml
deleted file mode 100644
index 030aa76c1c..0000000000
--- a/benchmark/mjit_exec_vm2vm.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-type: lib/benchmark_driver/runner/mjit_exec
-num_methods: [1]
-#num_methods: (1..100).to_a + [200, 300, 400, 500, 600, 700, 800, 900, 1000]
-loop_count: 50000000
-from_jit: false
-to_jit: false
diff --git a/benchmark/mjit_integer.yml b/benchmark/mjit_integer.yml
index cd3288978b..a6b5c9ee16 100644
--- a/benchmark/mjit_integer.yml
+++ b/benchmark/mjit_integer.yml
@@ -2,25 +2,31 @@ 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/module_eqq.yml b/benchmark/module_eqq.yml
new file mode 100644
index 0000000000..a561fb86dc
--- /dev/null
+++ b/benchmark/module_eqq.yml
@@ -0,0 +1,27 @@
+prelude: |
+  class SimpleClass; end
+  class MediumClass
+    10.times { include Module.new }
+  end
+  class LargeClass
+    100.times { include Module.new }
+  end
+  class HugeClass
+    300.times { include Module.new }
+  end
+  SimpleObj = SimpleClass.new
+  MediumObj = MediumClass.new
+  LargeObj = LargeClass.new
+  HugeObj = HugeClass.new
+benchmark:
+  simple_class_eqq_simple_obj: |
+    SimpleClass === SimpleObj
+  medium_class_eqq_simple_obj: |
+    MediumClass === SimpleObj
+  simple_class_eqq_medium_obj: |
+    SimpleClass === MediumObj
+  simple_class_eqq_large_obj: |
+    SimpleClass === LargeObj
+  simple_class_eqq_huge_obj: |
+    SimpleClass === HugeObj
+loop_count: 20000000
diff --git a/benchmark/nilclass.yml b/benchmark/nilclass.yml
new file mode 100644
index 0000000000..fba67a5f6a
--- /dev/null
+++ b/benchmark/nilclass.yml
@@ -0,0 +1,6 @@
+benchmark:
+  to_i: |
+    nil.to_i
+  to_f: |
+    nil.to_f
+loop_count: 100000
diff --git a/benchmark/numeric_methods.yml b/benchmark/numeric_methods.yml
new file mode 100644
index 0000000000..1384902935
--- /dev/null
+++ b/benchmark/numeric_methods.yml
@@ -0,0 +1,29 @@
+prelude: |
+  int = 42
+  flo = 4.2
+benchmark:
+  real?: |
+    int.real?
+  integer?: |
+    flo.integer?
+  finite?: |
+    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
new file mode 100644
index 0000000000..93ff463e41
--- /dev/null
+++ b/benchmark/object_allocate.yml
@@ -0,0 +1,21 @@
+prelude: |
+  class Eight
+    8.times { include(Module.new) }
+  end
+  class ThirtyTwo
+    32.times { include(Module.new) }
+  end
+  class SixtyFour
+    64.times { include(Module.new) }
+  end
+  class OneTwentyEight
+    128.times { include(Module.new) }
+  end
+  # Disable GC to see raw throughput:
+  GC.disable
+benchmark:
+  allocate_8_deep: Eight.new
+  allocate_32_deep: ThirtyTwo.new
+  allocate_64_deep: SixtyFour.new
+  allocate_128_deep: OneTwentyEight.new
+loop_count: 100000
diff --git a/benchmark/objspace_dump_all.yml b/benchmark/objspace_dump_all.yml
new file mode 100644
index 0000000000..ebab562d2e
--- /dev/null
+++ b/benchmark/objspace_dump_all.yml
@@ -0,0 +1,13 @@
+prelude: |
+  require 'objspace'
+  require 'tempfile'
+  $objs = 1_000.times.map { Object.new }
+  $strings = 1_000.times.map { |i| "string #{i}" }
+  $file = Tempfile.new('heap')
+  $dev_null = File.open(File::NULL, 'w+')
+
+benchmark:
+  dump_all_string: "ObjectSpace.dump_all(output: :string)"
+  dump_all_file: "ObjectSpace.dump_all(output: $file)"
+  dump_all_dev_null: "ObjectSpace.dump_all(output: $dev_null)"
+loop_count: 1
diff --git a/benchmark/ractor_const.yml b/benchmark/ractor_const.yml
new file mode 100644
index 0000000000..d7ab74bdca
--- /dev/null
+++ b/benchmark/ractor_const.yml
@@ -0,0 +1,4 @@
+type: lib/benchmark_driver/runner/ractor
+benchmark:
+  ractor_const: Object
+ractor: 1
diff --git a/benchmark/ractor_float_to_s.yml b/benchmark/ractor_float_to_s.yml
new file mode 100644
index 0000000000..8f492be668
--- /dev/null
+++ b/benchmark/ractor_float_to_s.yml
@@ -0,0 +1,8 @@
+type: lib/benchmark_driver/runner/ractor
+prelude: |
+  FLOATS = [*0.0.step(1.0, 0.001)]
+benchmark:
+  ractor_float_to_s: |
+    FLOATS.each {|f| f.to_s}
+loop_count: 100
+ractor: 2
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/so_nbody.rb b/benchmark/so_nbody.rb
index d6c5bb9e61..9884fc4edc 100644
--- a/benchmark/so_nbody.rb
+++ b/benchmark/so_nbody.rb
@@ -12,38 +12,38 @@ def _puts *args
 end
 
 class Planet
- attr_accessor :x, :y, :z, :vx, :vy, :vz, :mass
+  attr_accessor :x, :y, :z, :vx, :vy, :vz, :mass
 
- def initialize(x, y, z, vx, vy, vz, mass)
-  @x, @y, @z = x, y, z
-  @vx, @vy, @vz = vx * DAYS_PER_YEAR, vy * DAYS_PER_YEAR, vz * DAYS_PER_YEAR
-  @mass = mass * SOLAR_MASS
- end
-
- def move_from_i(bodies, nbodies, dt, i)
-  while i < nbodies
-   b2 = bodies[i]
-   dx = @x - b2.x
-   dy = @y - b2.y
-   dz = @z - b2.z
-
-   distance = Math.sqrt(dx * dx + dy * dy + dz * dz)
-   mag = dt / (distance * distance * distance)
-   b_mass_mag, b2_mass_mag = @mass * mag, b2.mass * mag
-
-   @vx -= dx * b2_mass_mag
-   @vy -= dy * b2_mass_mag
-   @vz -= dz * b2_mass_mag
-   b2.vx += dx * b_mass_mag
-   b2.vy += dy * b_mass_mag
-   b2.vz += dz * b_mass_mag
-   i += 1
+  def initialize(x, y, z, vx, vy, vz, mass)
+    @x, @y, @z = x, y, z
+    @vx, @vy, @vz = vx * DAYS_PER_YEAR, vy * DAYS_PER_YEAR, vz * DAYS_PER_YEAR
+    @mass = mass * SOLAR_MASS
   end
 
-  @x += dt * @vx
-  @y += dt * @vy
-  @z += dt * @vz
- end
+  def move_from_i(bodies, nbodies, dt, i)
+    while i < nbodies
+      b2 = bodies[i]
+      dx = @x - b2.x
+      dy = @y - b2.y
+      dz = @z - b2.z
+
+      distance = Math.sqrt(dx * dx + dy * dy + dz * dz)
+      mag = dt / (distance * distance * distance)
+      b_mass_mag, b2_mass_mag = @mass * mag, b2.mass * mag
+
+      @vx -= dx * b2_mass_mag
+      @vy -= dy * b2_mass_mag
+      @vz -= dz * b2_mass_mag
+      b2.vx += dx * b_mass_mag
+      b2.vy += dy * b_mass_mag
+      b2.vz += dz * b_mass_mag
+      i += 1
+    end
+
+    @x += dt * @vx
+    @y += dt * @vy
+    @z += dt * @vz
+  end
 end
 
 def energy(bodies)
diff --git a/benchmark/string_concat.yml b/benchmark/string_concat.yml
new file mode 100644
index 0000000000..e65c00cca9
--- /dev/null
+++ b/benchmark/string_concat.yml
@@ -0,0 +1,45 @@
+prelude: |
+  CHUNK = "a" * 64
+  UCHUNK = "é" * 32
+  GC.disable # GC causes a lot of variance
+benchmark:
+  binary_concat_7bit: |
+    buffer = String.new(capacity: 4096, encoding: Encoding::BINARY)
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+  utf8_concat_7bit: |
+    buffer = String.new(capacity: 4096, encoding: Encoding::UTF_8)
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+    buffer << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK << CHUNK
+  utf8_concat_UTF8: |
+    buffer = String.new(capacity: 4096, encoding: Encoding::UTF_8)
+    buffer << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK
+    buffer << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK
+    buffer << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK
+    buffer << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK
+    buffer << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK
+    buffer << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK
+    buffer << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK
+    buffer << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK << UCHUNK
+  interpolation: |
+    buffer = "#{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}#{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}#{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}#{CHUNK}#{CHUNK}"
diff --git a/benchmark/time_at.yml b/benchmark/time_at.yml
new file mode 100644
index 0000000000..3247efbe77
--- /dev/null
+++ b/benchmark/time_at.yml
@@ -0,0 +1,7 @@
+prelude: |
+  # frozen_string_literal: true
+benchmark:
+  - 'Time.at(0)'
+  - 'Time.at(0, 500)'
+  - 'Time.at(0, in: "+09:00")'
+  - 'Time.at(0, 500, in: "+09:00")'
diff --git a/benchmark/time_new.yml b/benchmark/time_new.yml
new file mode 100644
index 0000000000..5947dd3a41
--- /dev/null
+++ b/benchmark/time_new.yml
@@ -0,0 +1,4 @@
+benchmark:
+  - 'Time.new(2021)'
+  - 'Time.new(2021, 8, 22)'
+  - 'Time.new(2021, 8, 22, in: "+09:00")'
diff --git a/benchmark/time_now.yml b/benchmark/time_now.yml
new file mode 100644
index 0000000000..f6d6a31489
--- /dev/null
+++ b/benchmark/time_now.yml
@@ -0,0 +1,3 @@
+benchmark:
+  - 'Time.now'
+  - 'Time.now(in: "+09:00")'
diff --git a/benchmark/time_parse.yml b/benchmark/time_parse.yml
new file mode 100644
index 0000000000..6060b58bc6
--- /dev/null
+++ b/benchmark/time_parse.yml
@@ -0,0 +1,10 @@
+prelude: |
+  require 'time'
+  inspect = "2021-08-23 09:57:02 +0900"
+  iso8601 = "2021-08-23T09:57:02+09:00"
+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/vm_case_classes.yml b/benchmark/vm_case_classes.yml
new file mode 100644
index 0000000000..cacc4f0464
--- /dev/null
+++ b/benchmark/vm_case_classes.yml
@@ -0,0 +1,9 @@
+benchmark:
+  vm_case_classes: |
+    case :foo
+    when Hash
+      raise
+    when Array
+      raise
+    end
+loop_count: 6000000
diff --git a/benchmark/vm_const.yml b/benchmark/vm_const.yml
index 6064d4eed0..8939ca0cd3 100644
--- a/benchmark/vm_const.yml
+++ b/benchmark/vm_const.yml
@@ -1,7 +1,13 @@
 prelude: |
   Const = 1
+  A = B = C = D = E = F = G = H = I = J = K = L = M = N = O = P = Q = R = S = T = U = V = W = X = Y = Z = 1
+  def foo
+    A; B; C; D; E; F; G; H; I; J; K; L; M; N; O; P; Q; R; S; T; U; V; W; X; Y; Z
+  end
 benchmark:
   vm_const: |
     j = Const
     k = Const
+  vm_const_many: |
+    foo
 loop_count: 30000000
diff --git a/benchmark/vm_cvar.yml b/benchmark/vm_cvar.yml
new file mode 100644
index 0000000000..1d0e161829
--- /dev/null
+++ b/benchmark/vm_cvar.yml
@@ -0,0 +1,20 @@
+prelude: |
+  class A
+    @@foo = 1
+
+    def self.foo
+      @@foo
+    end
+
+    ("A".."Z").each do |module_name|
+      eval <<-EOM
+        module #{module_name}
+        end
+
+        include #{module_name}
+      EOM
+    end
+  end
+benchmark:
+  vm_cvar: A.foo
+loop_count: 600000
diff --git a/benchmark/vm_dstr_ary.rb b/benchmark/vm_dstr_ary.rb
new file mode 100644
index 0000000000..1d3aa3b97b
--- /dev/null
+++ b/benchmark/vm_dstr_ary.rb
@@ -0,0 +1,6 @@
+i = 0
+x = y = []
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end
diff --git a/benchmark/vm_dstr_bool.rb b/benchmark/vm_dstr_bool.rb
new file mode 100644
index 0000000000..631ca54755
--- /dev/null
+++ b/benchmark/vm_dstr_bool.rb
@@ -0,0 +1,7 @@
+i = 0
+x = true
+y = false
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end
diff --git a/benchmark/vm_dstr_class_module.rb b/benchmark/vm_dstr_class_module.rb
new file mode 100644
index 0000000000..becf0861c7
--- /dev/null
+++ b/benchmark/vm_dstr_class_module.rb
@@ -0,0 +1,10 @@
+i = 0
+class A; end unless defined?(A)
+module B; end unless defined?(B)
+x = A
+y = B
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end
+
diff --git a/benchmark/vm_dstr_digit.rb b/benchmark/vm_dstr_digit.rb
new file mode 100644
index 0000000000..caaa395192
--- /dev/null
+++ b/benchmark/vm_dstr_digit.rb
@@ -0,0 +1,7 @@
+i = 0
+x = 0
+y = 9
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end
diff --git a/benchmark/vm_dstr_int.rb b/benchmark/vm_dstr_int.rb
new file mode 100644
index 0000000000..ed380d7595
--- /dev/null
+++ b/benchmark/vm_dstr_int.rb
@@ -0,0 +1,5 @@
+i = 0
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{i}bar#{i}baz"
+end
diff --git a/benchmark/vm_dstr_nil.rb b/benchmark/vm_dstr_nil.rb
new file mode 100644
index 0000000000..ec4f5d6c67
--- /dev/null
+++ b/benchmark/vm_dstr_nil.rb
@@ -0,0 +1,6 @@
+i = 0
+x = y = nil
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end
diff --git a/benchmark/vm_dstr_obj.rb b/benchmark/vm_dstr_obj.rb
new file mode 100644
index 0000000000..fb78637ead
--- /dev/null
+++ b/benchmark/vm_dstr_obj.rb
@@ -0,0 +1,6 @@
+i = 0
+x = y = Object.new
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end
diff --git a/benchmark/vm_dstr_obj_def.rb b/benchmark/vm_dstr_obj_def.rb
new file mode 100644
index 0000000000..99ff7b98fb
--- /dev/null
+++ b/benchmark/vm_dstr_obj_def.rb
@@ -0,0 +1,8 @@
+i = 0
+o = Object.new
+def o.to_s; -""; end
+x = y = o
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end
diff --git a/benchmark/vm_dstr_str.rb b/benchmark/vm_dstr_str.rb
new file mode 100644
index 0000000000..45fc107892
--- /dev/null
+++ b/benchmark/vm_dstr_str.rb
@@ -0,0 +1,6 @@
+i = 0
+x = y = ""
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end
diff --git a/benchmark/vm_dstr_sym.rb b/benchmark/vm_dstr_sym.rb
new file mode 100644
index 0000000000..484b8f8150
--- /dev/null
+++ b/benchmark/vm_dstr_sym.rb
@@ -0,0 +1,6 @@
+i = 0
+x = y = :z
+while i<6_000_000 # benchmark loop 2
+  i += 1
+  str = "foo#{x}bar#{y}baz"
+end
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_iclass_super.yml b/benchmark/vm_iclass_super.yml
new file mode 100644
index 0000000000..21bb7db247
--- /dev/null
+++ b/benchmark/vm_iclass_super.yml
@@ -0,0 +1,20 @@
+prelude: |
+  class C
+    def m
+      1
+    end
+
+    ("A".."M").each do |module_name|
+      eval <<-EOM
+          module #{module_name}
+            def m; super; end
+          end
+          prepend #{module_name}
+      EOM
+    end
+  end
+
+  obj = C.new
+benchmark:
+  vm_iclass_super: obj.m
+loop_count: 6000000
diff --git a/benchmark/vm_ivar_embedded_obj_init.yml b/benchmark/vm_ivar_embedded_obj_init.yml
new file mode 100644
index 0000000000..74fe20a630
--- /dev/null
+++ b/benchmark/vm_ivar_embedded_obj_init.yml
@@ -0,0 +1,14 @@
+prelude: |
+  class C
+    def set_ivars
+      @a = nil
+      @b = nil
+      @c = nil
+    end
+  end
+
+  c = C.new
+benchmark:
+  vm_ivar_embedded_obj_init: |
+    c.set_ivars
+loop_count: 30000000
diff --git a/benchmark/vm_ivar_extended_obj_init.yml b/benchmark/vm_ivar_extended_obj_init.yml
new file mode 100644
index 0000000000..f054bab282
--- /dev/null
+++ b/benchmark/vm_ivar_extended_obj_init.yml
@@ -0,0 +1,16 @@
+prelude: |
+  class C
+    def set_ivars
+      @a = nil
+      @b = nil
+      @c = nil
+      @d = nil
+      @e = nil
+    end
+  end
+
+  c = C.new
+benchmark:
+  vm_ivar_extended_obj_init: |
+    c.set_ivars
+loop_count: 30000000
diff --git a/benchmark/vm_ivar_generic_get.yml b/benchmark/vm_ivar_generic_get.yml
new file mode 100644
index 0000000000..dae2d37671
--- /dev/null
+++ b/benchmark/vm_ivar_generic_get.yml
@@ -0,0 +1,17 @@
+prelude: |
+  class C < Array
+    attr_reader :a, :b, :c
+    def initialize
+      @a = nil
+      @b = nil
+      @c = nil
+    end
+  end
+
+  c = C.new
+benchmark:
+  vm_ivar_generic_get: |
+    c.a
+    c.b
+    c.c
+loop_count: 30000000
diff --git a/benchmark/vm_ivar_generic_set.yml b/benchmark/vm_ivar_generic_set.yml
new file mode 100644
index 0000000000..102a6577fb
--- /dev/null
+++ b/benchmark/vm_ivar_generic_set.yml
@@ -0,0 +1,14 @@
+prelude: |
+  class C < Array
+    def set_ivars
+      @a = nil
+      @b = nil
+      @c = nil
+    end
+  end
+
+  c = C.new
+benchmark:
+  vm_ivar_generic_set: |
+    c.set_ivars
+loop_count: 30000000
diff --git a/benchmark/vm_ivar_get.yml b/benchmark/vm_ivar_get.yml
new file mode 100644
index 0000000000..9174af6965
--- /dev/null
+++ b/benchmark/vm_ivar_get.yml
@@ -0,0 +1,37 @@
+prelude: |
+  class Example
+    def initialize
+      @v0 = 1
+      @v1 = 2
+      @v3 = 3
+      @levar = 1
+    end
+
+    def get_value_loop
+      sum = 0
+
+      i = 0
+      while i < 1000000
+        # 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
+
+  obj = Example.new
+benchmark:
+  vm_ivar_get: |
+    obj.get_value_loop
+loop_count: 100
diff --git a/benchmark/vm_ivar_get_unintialized.yml b/benchmark/vm_ivar_get_unintialized.yml
new file mode 100644
index 0000000000..a1ccfb06ce
--- /dev/null
+++ b/benchmark/vm_ivar_get_unintialized.yml
@@ -0,0 +1,12 @@
+prelude: |
+  class Example
+    def read
+      @uninitialized
+    end
+  end
+
+  obj = Example.new
+benchmark:
+  vm_ivar_get_uninitialized: |
+    obj.read
+loop_count: 30000000
diff --git a/benchmark/vm_ivar_lazy_set.yml b/benchmark/vm_ivar_lazy_set.yml
new file mode 100644
index 0000000000..7372ffcfbc
--- /dev/null
+++ b/benchmark/vm_ivar_lazy_set.yml
@@ -0,0 +1,12 @@
+prelude: |
+  class Example
+    def lazy_set
+      @uninitialized ||= 123
+    end
+  end
+
+  objs = 10000000.times.map { Example.new }
+benchmark:
+  vm_ivar_lazy_set: |
+    objs.each(&:lazy_set)
+loop_count: 1
diff --git a/benchmark/vm_ivar_of_class.yml b/benchmark/vm_ivar_of_class.yml
new file mode 100644
index 0000000000..172e28b2fd
--- /dev/null
+++ b/benchmark/vm_ivar_of_class.yml
@@ -0,0 +1,12 @@
+prelude: |
+  class C
+    @a = 1
+    def self.a
+      _a = @a; _a = @a; _a = @a; _a = @a; _a = @a;
+      _a = @a; _a = @a; _a = @a; _a = @a; _a = @a;
+    end
+  end
+benchmark:
+  vm_ivar_of_class: |
+    a = C.a
+loop_count: 30000000
diff --git a/benchmark/vm_ivar_of_class_set.yml b/benchmark/vm_ivar_of_class_set.yml
new file mode 100644
index 0000000000..2ea5199423
--- /dev/null
+++ b/benchmark/vm_ivar_of_class_set.yml
@@ -0,0 +1,11 @@
+prelude: |
+  class C
+    @a = 1
+    def self.a o
+      @a = o; @a = o; @a = o; @a = o; @a = o; @a = o;
+    end
+  end
+benchmark:
+  vm_ivar_of_class_set: |
+    a = C.a(nil)
+loop_count: 30000000
diff --git a/benchmark/vm_ivar_set_on_instance.yml b/benchmark/vm_ivar_set_on_instance.yml
new file mode 100644
index 0000000000..91857b7742
--- /dev/null
+++ b/benchmark/vm_ivar_set_on_instance.yml
@@ -0,0 +1,35 @@
+prelude: |
+  class TheClass
+    def initialize
+      @v0 = 1
+      @v1 = 2
+      @v3 = 3
+      @levar = 1
+    end
+
+    def set_value_loop
+      # 1M
+      i = 0
+      while i < 1000000
+        # 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
+
+  obj = TheClass.new
+
+benchmark:
+  vm_ivar_set_on_instance: |
+    obj.set_value_loop
+loop_count: 100
diff --git a/benchmark/vm_ivar_set_subclass.yml b/benchmark/vm_ivar_set_subclass.yml
new file mode 100644
index 0000000000..bc8bf5bf6b
--- /dev/null
+++ b/benchmark/vm_ivar_set_subclass.yml
@@ -0,0 +1,20 @@
+prelude: |
+  class A
+    def set_ivars
+      @a = nil
+      @b = nil
+      @c = nil
+      @d = nil
+      @e = nil
+    end
+  end
+  class B < A; end
+  class C < A; end
+
+  b = B.new
+  c = C.new
+benchmark:
+  vm_ivar_init_subclass: |
+    b.set_ivars
+    c.set_ivars
+loop_count: 3000000
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_send.yml b/benchmark/vm_send.yml
index 753d3e8318..f31bc7ac89 100644
--- a/benchmark/vm_send.yml
+++ b/benchmark/vm_send.yml
@@ -5,7 +5,10 @@ prelude: |
   end
 
   o = C.new
+  m = :m
 benchmark:
   vm_send: |
     o.__send__ :m
+  vm_send_var: |
+    o.__send__ m
 loop_count: 6000000
diff --git a/benchmark/vm_thread_condvar1.rb b/benchmark/vm_thread_condvar1.rb
index cf5706b23e..feed27c3ad 100644
--- a/benchmark/vm_thread_condvar1.rb
+++ b/benchmark/vm_thread_condvar1.rb
@@ -1,9 +1,9 @@
 # two threads, two mutex, two condvar ping-pong
 require 'thread'
-m1 = Mutex.new
-m2 = Mutex.new
-cv1 = ConditionVariable.new
-cv2 = ConditionVariable.new
+m1 = Thread::Mutex.new
+m2 = Thread::Mutex.new
+cv1 = Thread::ConditionVariable.new
+cv2 = Thread::ConditionVariable.new
 max = 100000
 i = 0
 wait = nil
diff --git a/benchmark/vm_thread_condvar2.rb b/benchmark/vm_thread_condvar2.rb
index 7c8dc19481..6590c4134b 100644
--- a/benchmark/vm_thread_condvar2.rb
+++ b/benchmark/vm_thread_condvar2.rb
@@ -1,16 +1,16 @@
 # many threads, one mutex, many condvars
 require 'thread'
-m = Mutex.new
-cv1 = ConditionVariable.new
-cv2 = ConditionVariable.new
+m = Thread::Mutex.new
+cv1 = Thread::ConditionVariable.new
+cv2 = Thread::ConditionVariable.new
 max = 1000
 n = 100
 waiting = 0
 scvs = []
 waiters = n.times.map do |i|
-  start_cv = ConditionVariable.new
+  start_cv = Thread::ConditionVariable.new
   scvs << start_cv
-  start_mtx = Mutex.new
+  start_mtx = Thread::Mutex.new
   start_mtx.synchronize do
     th = Thread.new(start_mtx, start_cv) do |sm, scv|
       m.synchronize do
diff --git a/bignum.c b/bignum.c
index 310e731934..cb2c3b6f07 100644
--- a/bignum.c
+++ b/bignum.c
@@ -23,8 +23,14 @@
 # include <ieeefp.h>
 #endif
 
+#if !defined(USE_GMP)
 #if defined(HAVE_LIBGMP) && defined(HAVE_GMP_H)
-# define USE_GMP
+# define USE_GMP 1
+#else
+# define USE_GMP 0
+#endif
+#endif
+#if USE_GMP
 # include <gmp.h>
 #endif
 
@@ -36,15 +42,12 @@
 #include "internal/numeric.h"
 #include "internal/object.h"
 #include "internal/sanitizers.h"
-#include "internal/util.h"
 #include "internal/variable.h"
 #include "internal/warnings.h"
 #include "ruby/thread.h"
 #include "ruby/util.h"
 #include "ruby_assert.h"
 
-#define RB_BIGNUM_TYPE_P(x) RB_TYPE_P((x), T_BIGNUM)
-
 const char ruby_digitmap[] = "0123456789abcdefghijklmnopqrstuvwxyz";
 
 #ifndef SIZEOF_BDIGIT_DBL
@@ -75,7 +78,7 @@ STATIC_ASSERT(sizeof_long_and_sizeof_bdigit, SIZEOF_BDIGIT % SIZEOF_LONG == 0);
 #else
 #   define HOST_BIGENDIAN_P 0
 #endif
-/* (!LSHIFTABLE(d, n) ? 0 : (n)) is same as n but suppress a warning, C4293, by Visual Studio.  */
+/* (!LSHIFTABLE(d, n) ? 0 : (n)) is the same as n but suppress a warning, C4293, by Visual Studio.  */
 #define LSHIFTABLE(d, n) ((n) < sizeof(d) * CHAR_BIT)
 #define LSHIFTX(d, n) (!LSHIFTABLE(d, n) ? 0 : ((d) << (!LSHIFTABLE(d, n) ? 0 : (n))))
 #define CLEAR_LOWBITS(d, numbits) ((d) & LSHIFTX(~((d)*0), (numbits)))
@@ -102,8 +105,8 @@ STATIC_ASSERT(sizeof_long_and_sizeof_bdigit, SIZEOF_BDIGIT % SIZEOF_LONG == 0);
 #endif
 
 #define BIGZEROP(x) (BIGNUM_LEN(x) == 0 || \
-		     (BDIGITS(x)[0] == 0 && \
-		      (BIGNUM_LEN(x) == 1 || bigzero_p(x))))
+                     (BDIGITS(x)[0] == 0 && \
+                      (BIGNUM_LEN(x) == 1 || bigzero_p(x))))
 #define BIGSIZE(x) (BIGNUM_LEN(x) == 0 ? (size_t)0 : \
     BDIGITS(x)[BIGNUM_LEN(x)-1] ? \
         (size_t)(BIGNUM_LEN(x)*SIZEOF_BDIGIT - nlz(BDIGITS(x)[BIGNUM_LEN(x)-1])/CHAR_BIT) : \
@@ -148,7 +151,7 @@ STATIC_ASSERT(sizeof_long_and_sizeof_bdigit, SIZEOF_BDIGIT % SIZEOF_LONG == 0);
 #define GMP_DIV_DIGITS 20
 #define GMP_BIG2STR_DIGITS 20
 #define GMP_STR2BIG_DIGITS 20
-#ifdef USE_GMP
+#if USE_GMP
 # define NAIVE_MUL_DIGITS GMP_MUL_DIGITS
 #else
 # define NAIVE_MUL_DIGITS KARATSUBA_MUL_DIGITS
@@ -159,15 +162,11 @@ typedef void (mulfunc_t)(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, c
 static mulfunc_t bary_mul_toom3_start;
 static mulfunc_t bary_mul_karatsuba_start;
 static BDIGIT bigdivrem_single(BDIGIT *qds, const BDIGIT *xds, size_t xn, BDIGIT y);
-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);
 
-static VALUE bigmul0(VALUE x, VALUE y);
-static void bary_mul_toom3(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yds, size_t yn, BDIGIT *wds, size_t wn);
 static VALUE bignew_1(VALUE klass, size_t len, int sign);
 static inline VALUE bigtrunc(VALUE x);
 
 static VALUE bigsq(VALUE x);
-static void bigdivmod(VALUE x, VALUE y, volatile VALUE *divp, volatile VALUE *modp);
 static inline VALUE power_cache_get_power(int base, int power_level, size_t *numdigits_ret);
 
 #if SIZEOF_BDIGIT <= SIZEOF_INT
@@ -420,9 +419,9 @@ bary_small_lshift(BDIGIT *zds, const BDIGIT *xds, size_t n, int shift)
     assert(0 <= shift && shift < BITSPERDIG);
 
     for (i=0; i<n; i++) {
-	num = num | (BDIGIT_DBL)*xds++ << shift;
-	*zds++ = BIGLO(num);
-	num = BIGDN(num);
+        num = num | (BDIGIT_DBL)*xds++ << shift;
+        *zds++ = BIGLO(num);
+        num = BIGDN(num);
     }
     return BIGLO(num);
 }
@@ -438,9 +437,9 @@ bary_small_rshift(BDIGIT *zds, const BDIGIT *xds, size_t n, int shift, BDIGIT hi
     num = BIGUP(higher_bdigit);
     for (i = 0; i < n; i++) {
         BDIGIT x = xds[n - i - 1];
-	num = (num | x) >> shift;
+        num = (num | x) >> shift;
         zds[n - i - 1] = BIGLO(num);
-	num = BIGUP(x);
+        num = BIGUP(x);
     }
 }
 
@@ -450,7 +449,7 @@ bary_zero_p(const BDIGIT *xds, size_t xn)
     if (xn == 0)
         return 1;
     do {
-	if (xds[--xn]) return 0;
+        if (xds[--xn]) return 0;
     } while (xn);
     return 1;
 }
@@ -467,7 +466,6 @@ static int
 bary_2comp(BDIGIT *ds, size_t n)
 {
     size_t i;
-    i = 0;
     for (i = 0; i < n; i++) {
         if (ds[i] != 0) {
             goto non_zero;
@@ -979,7 +977,7 @@ 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;
 }
@@ -989,7 +987,7 @@ 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;
@@ -1057,6 +1055,7 @@ integer_unpack_num_bdigits(size_t numwords, size_t wordsize, size_t nails, int *
             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);
+            (void)num_bdigits1;
         }
 #endif
     }
@@ -1351,9 +1350,9 @@ bary_subb(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yd
 
     num = borrow ? -1 : 0;
     for (i = 0; i < sn; i++) {
-	num += (BDIGIT_DBL_SIGNED)xds[i] - yds[i];
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
+        num += (BDIGIT_DBL_SIGNED)xds[i] - yds[i];
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
     }
     if (yn <= xn) {
         for (; i < xn; i++) {
@@ -1372,7 +1371,7 @@ bary_subb(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yd
     }
     if (num == 0) goto num_is_zero;
     for (; i < zn; i++) {
-	zds[i] = BDIGMAX;
+        zds[i] = BDIGMAX;
     }
     return 1;
 
@@ -1380,10 +1379,10 @@ bary_subb(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yd
     if (xds == zds && xn == zn)
         return 0;
     for (; i < xn; i++) {
-	zds[i] = xds[i];
+        zds[i] = xds[i];
     }
     for (; i < zn; i++) {
-	zds[i] = 0;
+        zds[i] = 0;
     }
     return 0;
 }
@@ -1410,27 +1409,27 @@ bary_addc(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yd
     assert(yn <= zn);
 
     if (xn > yn) {
-	const BDIGIT *tds;
-	tds = xds; xds = yds; yds = tds;
-	i = xn; xn = yn; yn = i;
+        const BDIGIT *tds;
+        tds = xds; xds = yds; yds = tds;
+        i = xn; xn = yn; yn = i;
     }
 
     num = carry ? 1 : 0;
     for (i = 0; i < xn; i++) {
-	num += (BDIGIT_DBL)xds[i] + yds[i];
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
+        num += (BDIGIT_DBL)xds[i] + yds[i];
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
     }
     for (; i < yn; i++) {
         if (num == 0) goto num_is_zero;
-	num += yds[i];
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
+        num += yds[i];
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
     }
     for (; i < zn; i++) {
         if (num == 0) goto num_is_zero;
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
     }
     return num != 0;
 
@@ -1438,10 +1437,10 @@ bary_addc(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yd
     if (yds == zds && yn == zn)
         return 0;
     for (; i < yn; i++) {
-	zds[i] = yds[i];
+        zds[i] = yds[i];
     }
     for (; i < zn; i++) {
-	zds[i] = 0;
+        zds[i] = 0;
     }
     return 0;
 }
@@ -1580,7 +1579,7 @@ rb_big_mul_normal(VALUE x, VALUE y)
 
 /* efficient squaring (2 times faster than normal multiplication)
  * ref: Handbook of Applied Cryptography, Algorithm 14.16
- *      http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf
+ *      https://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf
  */
 static void
 bary_sq_fast(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn)
@@ -1598,30 +1597,30 @@ bary_sq_fast(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn)
         return;
 
     for (i = 0; i < xn-1; i++) {
-	v = (BDIGIT_DBL)xds[i];
-	if (!v)
+        v = (BDIGIT_DBL)xds[i];
+        if (!v)
             continue;
-	c = (BDIGIT_DBL)zds[i + i] + v * v;
-	zds[i + i] = BIGLO(c);
-	c = BIGDN(c);
-	v *= 2;
+        c = (BDIGIT_DBL)zds[i + i] + v * v;
+        zds[i + i] = BIGLO(c);
+        c = BIGDN(c);
+        v *= 2;
         vl = BIGLO(v);
         vh = (int)BIGDN(v);
-	for (j = i + 1; j < xn; j++) {
-	    w = (BDIGIT_DBL)xds[j];
-	    c += (BDIGIT_DBL)zds[i + j] + vl * w;
-	    zds[i + j] = BIGLO(c);
-	    c = BIGDN(c);
-	    if (vh)
+        for (j = i + 1; j < xn; j++) {
+            w = (BDIGIT_DBL)xds[j];
+            c += (BDIGIT_DBL)zds[i + j] + vl * w;
+            zds[i + j] = BIGLO(c);
+            c = BIGDN(c);
+            if (vh)
                 c += w;
-	}
-	if (c) {
-	    c += (BDIGIT_DBL)zds[i + xn];
-	    zds[i + xn] = BIGLO(c);
-	    c = BIGDN(c);
+        }
+        if (c) {
+            c += (BDIGIT_DBL)zds[i + xn];
+            zds[i + xn] = BIGLO(c);
+            c = BIGDN(c);
             if (c)
                 zds[i + xn + 1] += (BDIGIT)c;
-	}
+        }
     }
 
     /* i == xn-1 */
@@ -1646,13 +1645,21 @@ rb_big_sq_fast(VALUE x)
     return z;
 }
 
+static inline size_t
+max_size(size_t a, size_t b)
+{
+    return (a > b ? a : b);
+}
+
 /* balancing multiplication by slicing larger argument */
 static void
-bary_mul_balance_with_mulfunc(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yds, size_t yn, BDIGIT *wds, size_t wn, mulfunc_t *mulfunc)
+bary_mul_balance_with_mulfunc(BDIGIT *const zds, const size_t zn,
+                              const BDIGIT *const xds, const size_t xn,
+                              const BDIGIT *const yds, const size_t yn,
+                              BDIGIT *wds, size_t wn, mulfunc_t *const mulfunc)
 {
     VALUE work = 0;
-    size_t yn0 = yn;
-    size_t r, n;
+    size_t n;
 
     assert(xn + yn <= zn);
     assert(xn <= yn);
@@ -1660,14 +1667,26 @@ bary_mul_balance_with_mulfunc(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t
 
     BDIGITS_ZERO(zds, xn);
 
+    if (wn < xn) {
+        /* The condition when a new buffer is needed:
+         * 1. (2(xn+r) > zn-(yn-r)) => (2xn+r > zn-yn), at the last
+         *    iteration (or r == 0)
+         * 2. (2(xn+xn) > zn-(yn-r-xn)) => (3xn-r > zn-yn), at the
+         *    previous iteration.
+         */
+        const size_t r = yn % xn;
+        if (2*xn + yn + max_size(xn-r, r) > zn) {
+            wn = xn;
+            wds = ALLOCV_N(BDIGIT, work, wn);
+        }
+    }
+
     n = 0;
-    while (yn > 0) {
-        BDIGIT *tds;
-        size_t tn;
-	r = xn > yn ? yn : xn;
-        tn = xn + r;
+    while (yn > n) {
+        const size_t r = (xn > (yn - n) ? (yn - n) : xn);
+        const size_t tn = (xn + r);
         if (2 * (xn + r) <= zn - n) {
-            tds = zds + n + xn + r;
+            BDIGIT *const tds = zds + n + xn + r;
             mulfunc(tds, tn, xds, xn, yds + n, r, wds, wn);
             BDIGITS_ZERO(zds + n + xn, r);
             bary_add(zds + n, tn,
@@ -1675,21 +1694,25 @@ bary_mul_balance_with_mulfunc(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t
                      tds, tn);
         }
         else {
+            BDIGIT *const tds = zds + n;
             if (wn < xn) {
+                /* xn is invariant, only once here */
+#if 0
                 wn = xn;
                 wds = ALLOCV_N(BDIGIT, work, wn);
+#else
+                rb_bug("wds is not enough: %" PRIdSIZE " for %" PRIdSIZE, wn, xn);
+#endif
             }
-            tds = zds + n;
             MEMCPY(wds, zds + n, BDIGIT, xn);
             mulfunc(tds, tn, xds, xn, yds + n, r, wds+xn, wn-xn);
             bary_add(zds + n, tn,
                      zds + n, tn,
                      wds, xn);
         }
-	yn -= r;
-	n += r;
+        n += r;
     }
-    BDIGITS_ZERO(zds+xn+yn0, zn - (xn+yn0));
+    BDIGITS_ZERO(zds+xn+yn, zn - (xn+yn));
 
     if (work)
         ALLOCV_END(work);
@@ -2006,7 +2029,7 @@ bary_mul_toom3(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGI
     }
 
     /*
-     * ref. http://en.wikipedia.org/wiki/Toom%E2%80%93Cook_multiplication
+     * ref. https://en.wikipedia.org/wiki/Toom%E2%80%93Cook_multiplication
      *
      * x(b) = x0 * b^0 + x1 * b^1 + x2 * b^2
      * y(b) = y0 * b^0 + y1 * b^1 + y2 * b^2
@@ -2079,21 +2102,21 @@ bary_mul_toom3(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGI
         v3n = u3n; v3ds = u3ds; v3p = u3p;
     }
     else {
-	/* v1 <- y0 + y2 */
+        /* v1 <- y0 + y2 */
         bary_add(v1ds, v1n, y0ds, y0n, y2ds, y2n);
         v1p = 1;
 
-	/* y(-1) : v2 <- v1 - y1 = y0 - y1 + y2 */
+        /* y(-1) : v2 <- v1 - y1 = y0 - y1 + y2 */
         v2p = 1;
         if (bary_sub(v2ds, v2n, v1ds, v1n, y1ds, y1n)) {
             bary_2comp(v2ds, v2n);
             v2p = 0;
         }
 
-	/* y(1) : v1 <- v1 + y1 = y0 + y1 + y2 */
+        /* y(1) : v1 <- v1 + y1 = y0 + y1 + y2 */
         bary_add(v1ds, v1n, v1ds, v1n, y1ds, y1n);
 
-	/* y(-2) : v3 <- 2 * (v2 + y2) - y0 = y0 - 2 * (y1 - 2 * y2) */
+        /* y(-2) : v3 <- 2 * (v2 + y2) - y0 = y0 - 2 * (y1 - 2 * y2) */
         v3p = 1;
         if (v2p) {
             bary_add(v3ds, v3n, v2ds, v2n, y2ds, y2n);
@@ -2286,7 +2309,7 @@ rb_big_mul_toom3(VALUE x, VALUE y)
     return z;
 }
 
-#ifdef USE_GMP
+#if USE_GMP
 static inline void
 bdigits_to_mpz(mpz_t mp, const BDIGIT *digits, size_t len)
 {
@@ -2359,9 +2382,9 @@ bary_sparse_p(const BDIGIT *ds, size_t n)
 {
     long c = 0;
 
-    if (          ds[rb_genrand_ulong_limited(n / 2) + n / 4]) c++;
-    if (c <= 1 && ds[rb_genrand_ulong_limited(n / 2) + n / 4]) c++;
-    if (c <= 1 && ds[rb_genrand_ulong_limited(n / 2) + n / 4]) c++;
+    if (          ds[2 * n / 5]) c++;
+    if (c <= 1 && ds[    n / 2]) c++;
+    if (c <= 1 && ds[3 * n / 5]) c++;
 
     return (c <= 1) ? 1 : 0;
 }
@@ -2424,8 +2447,8 @@ bary_mul_precheck(BDIGIT **zdsp, size_t *znp, const BDIGIT **xdsp, size_t *xnp,
     if (xn > yn) {
         const BDIGIT *tds;
         size_t tn;
-	tds = xds; xds = yds; yds = tds;
-	tn = xn; xn = yn; yn = tn;
+        tds = xds; xds = yds; yds = tds;
+        tn = xn; xn = yn; yn = tn;
     }
     assert(xn <= yn);
 
@@ -2551,7 +2574,7 @@ bary_mul(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yds
         }
     }
 
-#ifdef USE_GMP
+#if USE_GMP
     bary_mul_gmp(zds, zn, xds, xn, yds, yn);
 #else
     bary_mul_toom3_start(zds, zn, xds, xn, yds, yn, NULL, 0);
@@ -2575,26 +2598,26 @@ bigdivrem1(void *ptr)
     BDIGIT q;
 
     do {
-	if (bds->stop) {
-	    bds->zn = zn;
-	    return 0;
+        if (bds->stop) {
+            bds->zn = zn;
+            return 0;
         }
-	if (zds[zn-1] == yds[yn-1]) q = BDIGMAX;
-	else q = (BDIGIT)((BIGUP(zds[zn-1]) + zds[zn-2])/yds[yn-1]);
-	if (q) {
+        if (zds[zn-1] == yds[yn-1]) q = BDIGMAX;
+        else q = (BDIGIT)((BIGUP(zds[zn-1]) + zds[zn-2])/yds[yn-1]);
+        if (q) {
             num = bigdivrem_mulsub(zds+zn-(yn+1), yn+1,
                                    q,
                                    yds, yn);
-	    while (num) { /* "add back" required */
-		q--;
+            while (num) { /* "add back" required */
+                q--;
                 num = bary_add(zds+zn-(yn+1), yn,
                                zds+zn-(yn+1), yn,
                                yds, yn);
                 num--;
-	    }
-	}
+            }
+        }
         zn--;
-	zds[zn] = q;
+        zds[zn] = q;
     } while (zn > yn);
     return 0;
 }
@@ -2663,16 +2686,16 @@ bigdivrem_restoring(BDIGIT *zds, size_t zn, BDIGIT *yds, size_t yn)
     bds.zn = zn - ynzero;
     if (bds.zn > 10000 || bds.yn > 10000) {
       retry:
-	bds.stop = Qfalse;
+        bds.stop = Qfalse;
         rb_nogvl(bigdivrem1, &bds, rb_big_stop, &bds, RB_NOGVL_UBF_ASYNC_SAFE);
 
-	if (bds.stop == Qtrue) {
-	    /* execute trap handler, but exception was not raised. */
-	    goto retry;
-	}
+        if (bds.stop == Qtrue) {
+            /* execute trap handler, but exception was not raised. */
+            goto retry;
+        }
     }
     else {
-	bigdivrem1(&bds);
+        bigdivrem1(&bds);
     }
 }
 
@@ -2771,7 +2794,7 @@ rb_big_divrem_normal(VALUE x, VALUE y)
     return rb_assoc_new(q, r);
 }
 
-#ifdef USE_GMP
+#if USE_GMP
 static void
 bary_divmod_gmp(BDIGIT *qds, size_t qn, BDIGIT *rds, size_t rn, const BDIGIT *xds, size_t xn, const BDIGIT *yds, size_t yn)
 {
@@ -2855,7 +2878,7 @@ rb_big_divrem_gmp(VALUE x, VALUE y)
 static void
 bary_divmod_branch(BDIGIT *qds, size_t qn, BDIGIT *rds, size_t rn, const BDIGIT *xds, size_t xn, const BDIGIT *yds, size_t yn)
 {
-#ifdef USE_GMP
+#if USE_GMP
     if (GMP_DIV_DIGITS < xn) {
         bary_divmod_gmp(qds, qn, rds, rn, xds, xn, yds, yn);
         return;
@@ -2914,30 +2937,6 @@ bary_divmod(BDIGIT *qds, size_t qn, BDIGIT *rds, size_t rn, const BDIGIT *xds, s
 # define BIGNUM_DEBUG (0+RUBY_DEBUG)
 #endif
 
-#if BIGNUM_DEBUG
-#define ON_DEBUG(x) do { x; } while (0)
-static void
-dump_bignum(VALUE x)
-{
-    long i;
-    printf("%c0x0", BIGNUM_SIGN(x) ? '+' : '-');
-    for (i = BIGNUM_LEN(x); i--; ) {
-        printf("_%0*"PRIxBDIGIT, SIZEOF_BDIGIT*2, BDIGITS(x)[i]);
-    }
-    printf(", len=%"PRIuSIZE, BIGNUM_LEN(x));
-    puts("");
-}
-
-static VALUE
-rb_big_dump(VALUE x)
-{
-    dump_bignum(x);
-    return x;
-}
-#else
-#define ON_DEBUG(x)
-#endif
-
 static int
 bigzero_p(VALUE x)
 {
@@ -2954,7 +2953,7 @@ int
 rb_cmpint(VALUE val, VALUE a, VALUE b)
 {
     if (NIL_P(val)) {
-	rb_cmperr(a, b);
+        rb_cmperr(a, b);
     }
     if (FIXNUM_P(val)) {
         long l = FIX2LONG(val);
@@ -2963,9 +2962,9 @@ rb_cmpint(VALUE val, VALUE a, VALUE b)
         return 0;
     }
     if (RB_BIGNUM_TYPE_P(val)) {
-	if (BIGZEROP(val)) return 0;
-	if (BIGNUM_SIGN(val)) return 1;
-	return -1;
+        if (BIGZEROP(val)) return 0;
+        if (BIGNUM_SIGN(val)) return 1;
+        return -1;
     }
     if (RTEST(rb_funcall(val, '>', 1, INT2FIX(0)))) return 1;
     if (RTEST(rb_funcall(val, '<', 1, INT2FIX(0)))) return -1;
@@ -2975,8 +2974,8 @@ rb_cmpint(VALUE val, VALUE a, VALUE b)
 #define BIGNUM_SET_LEN(b,l) \
     (BIGNUM_EMBED_P(b) ? \
      (void)(RBASIC(b)->flags = \
-	    (RBASIC(b)->flags & ~BIGNUM_EMBED_LEN_MASK) | \
-	    ((l) << BIGNUM_EMBED_LEN_SHIFT)) : \
+            (RBASIC(b)->flags & ~BIGNUM_EMBED_LEN_MASK) | \
+            ((l) << BIGNUM_EMBED_LEN_SHIFT)) : \
      (void)(RBIGNUM(b)->as.heap.len = (l)))
 
 static void
@@ -2984,33 +2983,33 @@ rb_big_realloc(VALUE big, size_t len)
 {
     BDIGIT *ds;
     if (BIGNUM_EMBED_P(big)) {
-	if (BIGNUM_EMBED_LEN_MAX < len) {
-	    ds = ALLOC_N(BDIGIT, len);
-	    MEMCPY(ds, RBIGNUM(big)->as.ary, BDIGIT, BIGNUM_EMBED_LEN_MAX);
-	    RBIGNUM(big)->as.heap.len = BIGNUM_LEN(big);
-	    RBIGNUM(big)->as.heap.digits = ds;
+        if (BIGNUM_EMBED_LEN_MAX < len) {
+            ds = ALLOC_N(BDIGIT, len);
+            MEMCPY(ds, RBIGNUM(big)->as.ary, BDIGIT, BIGNUM_EMBED_LEN_MAX);
+            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) {
-	    ds = RBIGNUM(big)->as.heap.digits;
+        if (len <= BIGNUM_EMBED_LEN_MAX) {
+            ds = RBIGNUM(big)->as.heap.digits;
             FL_SET_RAW(big, BIGNUM_EMBED_FLAG);
-	    BIGNUM_SET_LEN(big, len);
+            BIGNUM_SET_LEN(big, len);
             (void)VALGRIND_MAKE_MEM_UNDEFINED((void*)RBIGNUM(big)->as.ary, sizeof(RBIGNUM(big)->as.ary));
-	    if (ds) {
-		MEMCPY(RBIGNUM(big)->as.ary, ds, BDIGIT, len);
-		xfree(ds);
-	    }
-	}
-	else {
-	    if (BIGNUM_LEN(big) == 0) {
-		RBIGNUM(big)->as.heap.digits = ALLOC_N(BDIGIT, len);
-	    }
-	    else {
-		REALLOC_N(RBIGNUM(big)->as.heap.digits, BDIGIT, len);
-	    }
-	}
+            if (ds) {
+                MEMCPY(RBIGNUM(big)->as.ary, ds, BDIGIT, len);
+                xfree(ds);
+            }
+        }
+        else {
+            if (BIGNUM_LEN(big) == 0) {
+                RBIGNUM(big)->as.heap.digits = ALLOC_N(BDIGIT, len);
+            }
+            else {
+                REALLOC_N(RBIGNUM(big)->as.heap.digits, BDIGIT, len);
+            }
+        }
     }
 }
 
@@ -3096,7 +3095,7 @@ abs2twocomp(VALUE *xp, long *n_ret)
         MEMCPY(BDIGITS(z), ds, BDIGIT, n);
         bary_2comp(BDIGITS(z), n);
         hibits = BDIGMAX;
-	*xp = z;
+        *xp = z;
     }
     *n_ret = n;
     return hibits;
@@ -3120,7 +3119,7 @@ bigtrunc(VALUE x)
     if (len == 0) return x;
     while (--len && !ds[len]);
     if (BIGNUM_LEN(x) > len+1) {
-	rb_big_resize(x, len+1);
+        rb_big_resize(x, len+1);
     }
     return x;
 }
@@ -3173,7 +3172,7 @@ static VALUE
 bignorm(VALUE x)
 {
     if (RB_BIGNUM_TYPE_P(x)) {
-	x = bigfixize(x);
+        x = bigfixize(x);
     }
     return x;
 }
@@ -3195,8 +3194,8 @@ rb_uint2big(uintptr_t n)
     digits[0] = n;
 #else
     for (i = 0; i < bdigit_roomof(SIZEOF_VALUE); i++) {
-	digits[i] = BIGLO(n);
-	n = BIGDN(n);
+        digits[i] = BIGLO(n);
+        n = BIGDN(n);
     }
 #endif
 
@@ -3215,14 +3214,14 @@ rb_int2big(intptr_t n)
 
     if (n < 0) {
         u = 1 + (VALUE)(-(n + 1)); /* u = -n avoiding overflow */
-	neg = 1;
+        neg = 1;
     }
     else {
         u = n;
     }
     big = rb_uint2big(u);
     if (neg) {
-	BIGNUM_SET_NEGATIVE_SIGN(big);
+        BIGNUM_SET_NEGATIVE_SIGN(big);
     }
     return big;
 }
@@ -3381,7 +3380,7 @@ absint_numwords_generic(size_t numbytes, int nlz_bits_in_msbyte, size_t word_num
 
     if (sign == 2) {
 #if defined __GNUC__ && (__GNUC__ == 4 && __GNUC_MINOR__ == 4)
-	*nlz_bits_ret = 0;
+        *nlz_bits_ret = 0;
 #endif
         return (size_t)-1;
     }
@@ -3429,6 +3428,7 @@ rb_absint_numwords(VALUE val, size_t word_numbits, size_t *nlz_bits_ret)
             numwords0 = absint_numwords_generic(numbytes, nlz_bits_in_msbyte, word_numbits, &nlz_bits0);
             assert(numwords0 == numwords);
             assert(nlz_bits0 == nlz_bits);
+            (void)numwords0;
         }
 #endif
     }
@@ -3700,7 +3700,7 @@ rb_integer_unpack(const void *words, size_t numwords, size_t wordsize, size_t na
         }
         else if (num_bdigits == numberof(fixbuf)) {
             val = bignew((long)num_bdigits+1, 0);
-	    MEMCPY(BDIGITS(val), fixbuf, BDIGIT, num_bdigits);
+            MEMCPY(BDIGITS(val), fixbuf, BDIGIT, num_bdigits);
             BDIGITS(val)[num_bdigits++] = 1;
         }
         else {
@@ -3712,11 +3712,11 @@ rb_integer_unpack(const void *words, size_t numwords, size_t wordsize, size_t na
         BDIGIT_DBL u = fixbuf[0] + BIGUP(fixbuf[1]);
         if (u == 0)
             return LONG2FIX(0);
-	if (0 < sign && POSFIXABLE(u))
-            return LONG2FIX(u);
-	if (sign < 0 && BDIGIT_MSB(fixbuf[1]) == 0 &&
+        if (0 < sign && POSFIXABLE(u))
+            return LONG2FIX((long)u);
+        if (sign < 0 && BDIGIT_MSB(fixbuf[1]) == 0 &&
                 NEGFIXABLE(-(BDIGIT_DBL_SIGNED)u))
-            return LONG2FIX(-(BDIGIT_DBL_SIGNED)u);
+            return LONG2FIX((long)-(BDIGIT_DBL_SIGNED)u);
         val = bignew((long)num_bdigits, 0 <= sign);
         MEMCPY(BDIGITS(val), fixbuf, BDIGIT, num_bdigits);
     }
@@ -3766,41 +3766,41 @@ str2big_scan_digits(const char *s, const char *str, int base, int badcheck, size
     int c;
 
     if (!len) {
-	*num_digits_p = 0;
-	*len_p = 0;
-	return TRUE;
+        *num_digits_p = 0;
+        *len_p = 0;
+        return TRUE;
     }
 
     if (badcheck && *str == '_') return FALSE;
 
     while ((c = *str++) != 0) {
-	if (c == '_') {
-	    if (nondigit) {
+        if (c == '_') {
+            if (nondigit) {
                 if (badcheck) return FALSE;
-		break;
-	    }
-	    nondigit = (char) c;
-	}
-	else if ((c = conv_digit(c)) < 0 || c >= base) {
-	    break;
-	}
-	else {
-	    nondigit = 0;
-	    num_digits++;
-	    digits_end = str;
-	}
-	if (len > 0 && !--len) break;
+                break;
+            }
+            nondigit = (char) c;
+        }
+        else if ((c = conv_digit(c)) < 0 || c >= base) {
+            break;
+        }
+        else {
+            nondigit = 0;
+            num_digits++;
+            digits_end = str;
+        }
+        if (len > 0 && !--len) break;
     }
     if (badcheck && nondigit) return FALSE;
     if (badcheck && len) {
-	str--;
-	while (*str && ISSPACE(*str)) {
-	    str++;
-	    if (len > 0 && !--len) break;
-	}
-	if (len && *str) {
-	    return FALSE;
-	}
+        str--;
+        while (*str && ISSPACE(*str)) {
+            str++;
+            if (len > 0 && !--len) break;
+        }
+        if (len && *str) {
+            return FALSE;
+        }
     }
     *num_digits_p = num_digits;
     *len_p = digits_end - digits_start;
@@ -3975,7 +3975,7 @@ str2big_karatsuba(
     return z;
 }
 
-#ifdef USE_GMP
+#if USE_GMP
 static VALUE
 str2big_gmp(
     int sign,
@@ -4042,8 +4042,8 @@ rb_cstr_to_inum(const char *str, int base, int badcheck)
     char *end;
     VALUE ret = rb_cstr_parse_inum(str, -1, (badcheck ? NULL : &end), base);
     if (NIL_P(ret)) {
-	if (badcheck) rb_invalid_str(str, "Integer()");
-	ret = INT2FIX(0);
+        if (badcheck) rb_invalid_str(str, "Integer()");
+        ret = INT2FIX(0);
     }
     return ret;
 }
@@ -4067,7 +4067,7 @@ rb_cstr_to_inum(const char *str, int base, int badcheck)
 
 VALUE
 rb_int_parse_cstr(const char *str, ssize_t len, char **endp, size_t *ndigits,
-		  int base, int flags)
+                  int base, int flags)
 {
     const char *const s = str;
     char sign = 1;
@@ -4084,82 +4084,82 @@ rb_int_parse_cstr(const char *str, ssize_t len, char **endp, size_t *ndigits,
     const int badcheck = !endp;
 
 #define ADV(n) do {\
-	if (len > 0 && len <= (n)) goto bad; \
-	str += (n); \
-	len -= (n); \
+        if (len > 0 && len <= (n)) goto bad; \
+        str += (n); \
+        len -= (n); \
     } while (0)
 #define ASSERT_LEN() do {\
-	assert(len != 0); \
-	if (len0 >= 0) assert(s + len0 == str + len); \
+        assert(len != 0); \
+        if (len0 >= 0) assert(s + len0 == str + len); \
     } while (0)
 
     if (!str) {
         goto bad;
     }
     if (len && (flags & RB_INT_PARSE_SIGN)) {
-	while (ISSPACE(*str)) ADV(1);
+        while (ISSPACE(*str)) ADV(1);
 
-	if (str[0] == '+') {
-	    ADV(1);
-	}
-	else if (str[0] == '-') {
-	    ADV(1);
-	    sign = 0;
-	}
-	ASSERT_LEN();
+        if (str[0] == '+') {
+            ADV(1);
+        }
+        else if (str[0] == '-') {
+            ADV(1);
+            sign = 0;
+        }
+        ASSERT_LEN();
     }
     if (base <= 0) {
-	if (str[0] == '0' && len > 1) {
-	    switch (str[1]) {
-	      case 'x': case 'X':
-		base = 16;
-		ADV(2);
-		break;
-	      case 'b': case 'B':
-		base = 2;
-		ADV(2);
-		break;
-	      case 'o': case 'O':
-		base = 8;
-		ADV(2);
-		break;
-	      case 'd': case 'D':
-		base = 10;
-		ADV(2);
-		break;
-	      default:
-		base = 8;
-	    }
-	}
-	else if (base < -1) {
-	    base = -base;
-	}
-	else {
-	    base = 10;
-	}
+        if (str[0] == '0' && len > 1) {
+            switch (str[1]) {
+              case 'x': case 'X':
+                base = 16;
+                ADV(2);
+                break;
+              case 'b': case 'B':
+                base = 2;
+                ADV(2);
+                break;
+              case 'o': case 'O':
+                base = 8;
+                ADV(2);
+                break;
+              case 'd': case 'D':
+                base = 10;
+                ADV(2);
+                break;
+              default:
+                base = 8;
+            }
+        }
+        else if (base < -1) {
+            base = -base;
+        }
+        else {
+            base = 10;
+        }
     }
     else if (len == 1 || !(flags & RB_INT_PARSE_PREFIX)) {
-	/* no prefix */
+        /* no prefix */
     }
     else if (base == 2) {
-	if (str[0] == '0' && (str[1] == 'b'||str[1] == 'B')) {
-	    ADV(2);
-	}
+        if (str[0] == '0' && (str[1] == 'b'||str[1] == 'B')) {
+            ADV(2);
+        }
     }
     else if (base == 8) {
-	if (str[0] == '0' && (str[1] == 'o'||str[1] == 'O')) {
-	    ADV(2);
-	}
+        if (str[0] == '0' && (str[1] == 'o'||str[1] == 'O')) {
+            ADV(2);
+        }
     }
     else if (base == 10) {
-	if (str[0] == '0' && (str[1] == 'd'||str[1] == 'D')) {
-	    ADV(2);
-	}
+        if (str[0] == '0' && (str[1] == 'd'||str[1] == 'D')) {
+            ADV(2);
+        }
     }
     else if (base == 16) {
-	if (str[0] == '0' && (str[1] == 'x'||str[1] == 'X')) {
-	    ADV(2);
-	}
+        if (str[0] == '0' && (str[1] == 'x'||str[1] == 'X')) {
+            ADV(2);
+        }
     }
     if (!valid_radix_p(base)) {
         invalid_radix(base);
@@ -4167,80 +4167,79 @@ rb_int_parse_cstr(const char *str, ssize_t len, char **endp, size_t *ndigits,
     if (!len) goto bad;
     num_digits = str - s;
     if (*str == '0' && len != 1) { /* squeeze preceding 0s */
-	int us = 0;
-	const char *end = len < 0 ? NULL : str + len;
-	++num_digits;
-	while ((c = *++str) == '0' ||
-	       ((flags & RB_INT_PARSE_UNDERSCORE) && c == '_')) {
-	    if (c == '_') {
-		if (++us >= 2)
-		    break;
-	    }
-	    else {
-		++num_digits;
-		us = 0;
-	    }
-	    if (str == end) break;
-	}
-	if (!c || ISSPACE(c)) --str;
-	if (end) len = end - str;
-	ASSERT_LEN();
+        int us = 0;
+        const char *end = len < 0 ? NULL : str + len;
+        ++num_digits;
+        while ((c = *++str) == '0' ||
+               ((flags & RB_INT_PARSE_UNDERSCORE) && c == '_')) {
+            if (c == '_') {
+                if (++us >= 2)
+                    break;
+            }
+            else {
+                ++num_digits;
+                us = 0;
+            }
+            if (str == end) break;
+        }
+        if (!c || ISSPACE(c)) --str;
+        if (end) len = end - str;
     }
     c = *str;
     c = conv_digit(c);
     if (c < 0 || c >= base) {
-	if (!badcheck && num_digits) z = INT2FIX(0);
-	goto bad;
+        if (!badcheck && num_digits) z = INT2FIX(0);
+        goto bad;
     }
 
     if (ndigits) *ndigits = num_digits;
     val = ruby_scan_digits(str, len, base, &num_digits, &ov);
     if (!ov) {
-	const char *end = &str[num_digits];
-	if (num_digits > 0 && *end == '_' && (flags & RB_INT_PARSE_UNDERSCORE))
-	    goto bigparse;
-	if (endp) *endp = (char *)end;
-	if (ndigits) *ndigits += num_digits;
-	if (badcheck) {
-	    if (num_digits == 0) return Qnil; /* no number */
-	    while (len < 0 ? *end : end < str + len) {
-		if (!ISSPACE(*end)) return Qnil; /* trailing garbage */
-		end++;
-	    }
-	}
-
-	if (POSFIXABLE(val)) {
-	    if (sign) return LONG2FIX(val);
-	    else {
-		long result = -(long)val;
-		return LONG2FIX(result);
-	    }
-	}
-	else {
-	    VALUE big = rb_uint2big(val);
-	    BIGNUM_SET_SIGN(big, sign);
-	    return bignorm(big);
-	}
+        const char *end = &str[num_digits];
+        if (num_digits > 0 && *end == '_' && (flags & RB_INT_PARSE_UNDERSCORE))
+            goto bigparse;
+        if (endp) *endp = (char *)end;
+        if (ndigits) *ndigits += num_digits;
+        if (badcheck) {
+            if (num_digits == 0) return Qnil; /* no number */
+            while (len < 0 ? *end : end < str + len) {
+                if (!ISSPACE(*end)) return Qnil; /* trailing garbage */
+                end++;
+            }
+        }
+
+        if (POSFIXABLE(val)) {
+            if (sign) return LONG2FIX(val);
+            else {
+                long result = -(long)val;
+                return LONG2FIX(result);
+            }
+        }
+        else {
+            VALUE big = rb_uint2big(val);
+            BIGNUM_SET_SIGN(big, sign);
+            return bignorm(big);
+        }
     }
 
   bigparse:
     digits_start = str;
     if (!str2big_scan_digits(s, str, base, badcheck, &num_digits, &len))
-	goto bad;
+        goto bad;
     if (endp) *endp = (char *)(str + len);
     if (ndigits) *ndigits += num_digits;
     digits_end = digits_start + len;
 
     if (POW2_P(base)) {
         z = str2big_poweroftwo(sign, digits_start, digits_end, num_digits,
-			       bit_length(base-1));
+                               bit_length(base-1));
     }
     else {
         int digits_per_bdigits_dbl;
         maxpow_in_bdigit_dbl(base, &digits_per_bdigits_dbl);
         num_bdigits = roomof(num_digits, digits_per_bdigits_dbl)*2;
 
-#ifdef USE_GMP
+#if USE_GMP
         if (GMP_STR2BIG_DIGITS < num_bdigits) {
             z = str2big_gmp(sign, digits_start, digits_end, num_digits,
                     num_bdigits, base);
@@ -4269,7 +4268,7 @@ static VALUE
 rb_cstr_parse_inum(const char *str, ssize_t len, char **endp, int base)
 {
     return rb_int_parse_cstr(str, len, endp, NULL, base,
-			     RB_INT_PARSE_DEFAULT);
+                             RB_INT_PARSE_DEFAULT);
 }
 
 VALUE
@@ -4318,14 +4317,14 @@ rb_str2big_poweroftwo(VALUE arg, int base, int badcheck)
     s = str = StringValueCStr(arg);
     len = RSTRING_LEN(arg);
     if (*str == '-') {
-	len--;
+        len--;
         str++;
         positive_p = 0;
     }
 
     digits_start = str;
     if (!str2big_scan_digits(s, str, base, badcheck, &num_digits, &len))
-	invalid_integer(arg);
+        invalid_integer(arg);
     digits_end = digits_start + len;
 
     z = str2big_poweroftwo(positive_p, digits_start, digits_end, num_digits,
@@ -4357,14 +4356,14 @@ rb_str2big_normal(VALUE arg, int base, int badcheck)
     s = str = StringValuePtr(arg);
     len = RSTRING_LEN(arg);
     if (len > 0 && *str == '-') {
-	len--;
+        len--;
         str++;
         positive_p = 0;
     }
 
     digits_start = str;
     if (!str2big_scan_digits(s, str, base, badcheck, &num_digits, &len))
-	invalid_integer(arg);
+        invalid_integer(arg);
     digits_end = digits_start + len;
 
     maxpow_in_bdigit_dbl(base, &digits_per_bdigits_dbl);
@@ -4399,14 +4398,14 @@ rb_str2big_karatsuba(VALUE arg, int base, int badcheck)
     s = str = StringValuePtr(arg);
     len = RSTRING_LEN(arg);
     if (len > 0 && *str == '-') {
-	len--;
+        len--;
         str++;
         positive_p = 0;
     }
 
     digits_start = str;
     if (!str2big_scan_digits(s, str, base, badcheck, &num_digits, &len))
-	invalid_integer(arg);
+        invalid_integer(arg);
     digits_end = digits_start + len;
 
     maxpow_in_bdigit_dbl(base, &digits_per_bdigits_dbl);
@@ -4420,7 +4419,7 @@ rb_str2big_karatsuba(VALUE arg, int base, int badcheck)
     return bignorm(z);
 }
 
-#ifdef USE_GMP
+#if USE_GMP
 VALUE
 rb_str2big_gmp(VALUE arg, int base, int badcheck)
 {
@@ -4442,14 +4441,14 @@ rb_str2big_gmp(VALUE arg, int base, int badcheck)
     s = str = StringValuePtr(arg);
     len = RSTRING_LEN(arg);
     if (len > 0 && *str == '-') {
-	len--;
+        len--;
         str++;
         positive_p = 0;
     }
 
     digits_start = str;
     if (!str2big_scan_digits(s, str, base, badcheck, &num_digits, &len))
-	invalid_integer(arg);
+        invalid_integer(arg);
     digits_end = digits_start + len;
 
     maxpow_in_bdigit_dbl(base, &digits_per_bdigits_dbl);
@@ -4476,8 +4475,8 @@ rb_ull2big(unsigned LONG_LONG n)
     digits[0] = n;
 #else
     for (i = 0; i < bdigit_roomof(SIZEOF_LONG_LONG); i++) {
-	digits[i] = BIGLO(n);
-	n = BIGDN(n);
+        digits[i] = BIGLO(n);
+        n = BIGDN(n);
     }
 #endif
 
@@ -4496,14 +4495,14 @@ rb_ll2big(LONG_LONG n)
 
     if (n < 0) {
         u = 1 + (unsigned LONG_LONG)(-(n + 1)); /* u = -n avoiding overflow */
-	neg = 1;
+        neg = 1;
     }
     else {
         u = n;
     }
     big = rb_ull2big(u);
     if (neg) {
-	BIGNUM_SET_NEGATIVE_SIGN(big);
+        BIGNUM_SET_NEGATIVE_SIGN(big);
     }
     return big;
 }
@@ -4511,14 +4510,14 @@ rb_ll2big(LONG_LONG n)
 VALUE
 rb_ull2inum(unsigned LONG_LONG n)
 {
-    if (POSFIXABLE(n)) return LONG2FIX(n);
+    if (POSFIXABLE(n)) return LONG2FIX((long)n);
     return rb_ull2big(n);
 }
 
 VALUE
 rb_ll2inum(LONG_LONG n)
 {
-    if (FIXABLE(n)) return LONG2FIX(n);
+    if (FIXABLE(n)) return LONG2FIX((long)n);
     return rb_ll2big(n);
 }
 
@@ -4533,7 +4532,7 @@ rb_uint128t2big(uint128_t n)
     BDIGIT *digits = BDIGITS(big);
 
     for (i = 0; i < bdigit_roomof(SIZEOF_INT128_T); i++) {
-	digits[i] = BIGLO(RSHIFT(n ,BITSPERDIG*i));
+        digits[i] = BIGLO(RSHIFT(n ,BITSPERDIG*i));
     }
 
     i = bdigit_roomof(SIZEOF_INT128_T);
@@ -4551,14 +4550,14 @@ rb_int128t2big(int128_t n)
 
     if (n < 0) {
         u = 1 + (uint128_t)(-(n + 1)); /* u = -n avoiding overflow */
-	neg = 1;
+        neg = 1;
     }
     else {
         u = n;
     }
     big = rb_uint128t2big(u);
     if (neg) {
-	BIGNUM_SET_NEGATIVE_SIGN(big);
+        BIGNUM_SET_NEGATIVE_SIGN(big);
     }
     return big;
 }
@@ -4587,11 +4586,14 @@ 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);
@@ -4721,7 +4723,7 @@ 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_gc_register_mark_object(power);
     }
     if (numdigits_ret)
         *numdigits_ret = base36_numdigits_cache[base - 2][power_level];
@@ -4772,7 +4774,7 @@ big2str_2bdigits(struct big2str_struct *b2s, BDIGIT *xds, size_t xn, size_t tail
         } while (num);
         len = sizeof(buf) - j;
         big2str_alloc(b2s, len + taillen);
-	MEMCPY(b2s->ptr, buf + j, char, len);
+        MEMCPY(b2s->ptr, buf + j, char, len);
     }
     else {
         p = b2s->ptr;
@@ -4789,7 +4791,7 @@ big2str_2bdigits(struct big2str_struct *b2s, BDIGIT *xds, size_t xn, size_t tail
 
 static void
 big2str_karatsuba(struct big2str_struct *b2s, BDIGIT *xds, size_t xn, size_t wn,
-		  int power_level, size_t taillen)
+                  int power_level, size_t taillen)
 {
     VALUE b;
     size_t half_numdigits, lower_numdigits;
@@ -4819,17 +4821,17 @@ big2str_karatsuba(struct big2str_struct *b2s, BDIGIT *xds, size_t xn, size_t wn,
      */
 
     if (xn == 0 || bary_zero_p(xds, xn)) {
-	if (b2s->ptr) {
+        if (b2s->ptr) {
             /* When x is zero, power_cache_get_power(base, power_level) should be cached already. */
             power_cache_get_power(b2s->base, power_level, &len);
-	    memset(b2s->ptr, '0', len);
+            memset(b2s->ptr, '0', len);
             b2s->ptr += len;
-	}
+        }
         return;
     }
 
     if (power_level == 0) {
-	big2str_2bdigits(b2s, xds, xn, taillen);
+        big2str_2bdigits(b2s, xds, xn, taillen);
         return;
     }
 
@@ -4857,7 +4859,7 @@ big2str_karatsuba(struct big2str_struct *b2s, BDIGIT *xds, size_t xn, size_t wn,
             memset(b2s->ptr, '0', len);
             b2s->ptr += len;
         }
-	big2str_2bdigits(b2s, xds, xn, taillen);
+        big2str_2bdigits(b2s, xds, xn, taillen);
     }
     else {
         BDIGIT *qds, *rds;
@@ -4961,11 +4963,11 @@ big2str_generic(VALUE x, int base)
     BARY_TRUNC(xds, xn);
 
     if (xn == 0) {
-	return rb_usascii_str_new2("0");
+        return rb_usascii_str_new2("0");
     }
 
     if (!valid_radix_p(base))
-	invalid_radix(base);
+        invalid_radix(base);
 
     if (xn >= LONG_MAX/BITSPERDIG) {
         rb_raise(rb_eRangeError, "bignum too big to convert into `string'");
@@ -5002,7 +5004,7 @@ big2str_generic(VALUE x, int base)
     b2s_data.ptr = NULL;
 
     if (power_level == 0) {
-	big2str_2bdigits(&b2s_data, xds, xn, 0);
+        big2str_2bdigits(&b2s_data, xds, xn, 0);
     }
     else {
         VALUE tmpw = 0;
@@ -5011,7 +5013,7 @@ big2str_generic(VALUE x, int base)
         wn = power_level * BIGDIVREM_EXTRA_WORDS + BIGNUM_LEN(power);
         wds = ALLOCV_N(BDIGIT, tmpw, xn + wn);
         MEMCPY(wds, xds, BDIGIT, xn);
-	big2str_karatsuba(&b2s_data, wds, xn, wn, power_level, 0);
+        big2str_karatsuba(&b2s_data, wds, xn, wn, power_level, 0);
         if (tmpw)
             ALLOCV_END(tmpw);
     }
@@ -5030,7 +5032,7 @@ rb_big2str_generic(VALUE x, int base)
     return big2str_generic(x, base);
 }
 
-#ifdef USE_GMP
+#if USE_GMP
 static VALUE
 big2str_gmp(VALUE x, int base)
 {
@@ -5077,7 +5079,7 @@ rb_big2str1(VALUE x, int base)
     size_t xn;
 
     if (FIXNUM_P(x)) {
-	return rb_fix2str(x, base);
+        return rb_fix2str(x, base);
     }
 
     bigtrunc(x);
@@ -5086,11 +5088,11 @@ rb_big2str1(VALUE x, int base)
     BARY_TRUNC(xds, xn);
 
     if (xn == 0) {
-	return rb_usascii_str_new2("0");
+        return rb_usascii_str_new2("0");
     }
 
     if (!valid_radix_p(base))
-	invalid_radix(base);
+        invalid_radix(base);
 
     if (xn >= LONG_MAX/BITSPERDIG) {
         rb_raise(rb_eRangeError, "bignum too big to convert into `string'");
@@ -5101,7 +5103,7 @@ rb_big2str1(VALUE x, int base)
         return big2str_base_poweroftwo(x, base);
     }
 
-#ifdef USE_GMP
+#if USE_GMP
     if (GMP_BIG2STR_DIGITS < xn) {
         return big2str_gmp(x, base);
     }
@@ -5137,7 +5139,7 @@ big2ulong(VALUE x, const char *type)
 #else
     num = 0;
     for (i = 0; i < len; i++) {
-	num <<= BITSPERDIG;
+        num <<= BITSPERDIG;
         num += (unsigned long)ds[len - i - 1]; /* overflow is already checked */
     }
 #endif
@@ -5190,13 +5192,13 @@ 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
     num = 0;
     for (i = 0; i < len; i++) {
-	num = BIGUP(num);
+        num = BIGUP(num);
         num += ds[len - i - 1];
     }
 #endif
@@ -5246,23 +5248,23 @@ dbl2big(double d)
     double u = (d < 0)?-d:d;
 
     if (isinf(d)) {
-	rb_raise(rb_eFloatDomainError, d < 0 ? "-Infinity" : "Infinity");
+        rb_raise(rb_eFloatDomainError, d < 0 ? "-Infinity" : "Infinity");
     }
     if (isnan(d)) {
-	rb_raise(rb_eFloatDomainError, "NaN");
+        rb_raise(rb_eFloatDomainError, "NaN");
     }
 
     while (1.0 <= u) {
-	u /= (double)(BIGRAD);
-	i++;
+        u /= (double)(BIGRAD);
+        i++;
     }
     z = bignew(i, d>=0);
     digits = BDIGITS(z);
     while (i--) {
-	u *= BIGRAD;
-	c = (BDIGIT)u;
-	u -= c;
-	digits[i] = c;
+        u *= BIGRAD;
+        c = (BDIGIT)u;
+        u -= c;
+        digits[i] = c;
     }
 
     return z;
@@ -5282,28 +5284,28 @@ big2dbl(VALUE x)
     BDIGIT *ds = BDIGITS(x), dl;
 
     if (i) {
-	bits = i * BITSPERDIG - nlz(ds[i-1]);
-	if (bits > DBL_MANT_DIG+DBL_MAX_EXP) {
-	    d = HUGE_VAL;
-	}
-	else {
-	    if (bits > DBL_MANT_DIG+1)
-		lo = (bits -= DBL_MANT_DIG+1) / BITSPERDIG;
-	    else
-		bits = 0;
-	    while (--i > lo) {
-		d = ds[i] + BIGRAD*d;
-	    }
-	    dl = ds[i];
-	    if (bits && (dl & ((BDIGIT)1 << (bits %= BITSPERDIG)))) {
-		int carry = (dl & ~(BDIGMAX << bits)) != 0;
-		if (!carry) {
-		    while (i-- > 0) {
-			carry = ds[i] != 0;
-			if (carry) break;
-		    }
-		}
-		if (carry) {
+        bits = i * BITSPERDIG - nlz(ds[i-1]);
+        if (bits > DBL_MANT_DIG+DBL_MAX_EXP) {
+            d = HUGE_VAL;
+        }
+        else {
+            if (bits > DBL_MANT_DIG+1)
+                lo = (bits -= DBL_MANT_DIG+1) / BITSPERDIG;
+            else
+                bits = 0;
+            while (--i > lo) {
+                d = ds[i] + BIGRAD*d;
+            }
+            dl = ds[i];
+            if (bits && (dl & ((BDIGIT)1 << (bits %= BITSPERDIG)))) {
+                int carry = (dl & ~(BDIGMAX << bits)) != 0;
+                if (!carry) {
+                    while (i-- > 0) {
+                        carry = ds[i] != 0;
+                        if (carry) break;
+                    }
+                }
+                if (carry) {
                     BDIGIT mask = BDIGMAX;
                     BDIGIT bit = 1;
                     mask <<= bits;
@@ -5311,19 +5313,19 @@ big2dbl(VALUE x)
                     dl &= mask;
                     dl += bit;
                     dl = BIGLO(dl);
-		    if (!dl) d += 1;
-		}
-	    }
-	    d = dl + BIGRAD*d;
-	    if (lo) {
-		if (lo > INT_MAX / BITSPERDIG)
-		    d = HUGE_VAL;
-		else if (lo < INT_MIN / BITSPERDIG)
-		    d = 0.0;
-		else
-		    d = ldexp(d, (int)(lo * BITSPERDIG));
-	    }
-	}
+                    if (!dl) d += 1;
+                }
+            }
+            d = dl + BIGRAD*d;
+            if (lo) {
+                if (lo > INT_MAX / BITSPERDIG)
+                    d = HUGE_VAL;
+                else if (lo < INT_MIN / BITSPERDIG)
+                    d = 0.0;
+                else
+                    d = ldexp(d, (int)(lo * BITSPERDIG));
+            }
+        }
     }
     if (BIGNUM_NEGATIVE_P(x)) d = -d;
     return d;
@@ -5335,11 +5337,11 @@ rb_big2dbl(VALUE x)
     double d = big2dbl(x);
 
     if (isinf(d)) {
-	rb_warning("Bignum out of Float range");
-	if (d < 0.0)
-	    d = -HUGE_VAL;
-	else
-	    d = HUGE_VAL;
+        rb_warning("Integer out of Float range");
+        if (d < 0.0)
+            d = -HUGE_VAL;
+        else
+            d = HUGE_VAL;
     }
     return d;
 }
@@ -5409,7 +5411,7 @@ rb_integer_float_eq(VALUE x, VALUE y)
     double yd = RFLOAT_VALUE(y);
     double yi, yf;
 
-    if (isnan(yd) || isinf(yd))
+    if (!isfinite(yd))
         return Qfalse;
     yf = modf(yd, &yi);
     if (yf != 0)
@@ -5417,18 +5419,14 @@ rb_integer_float_eq(VALUE x, VALUE y)
     if (FIXNUM_P(x)) {
 #if SIZEOF_LONG * CHAR_BIT < DBL_MANT_DIG /* assume FLT_RADIX == 2 */
         double xd = (double)FIX2LONG(x);
-        if (xd != yd)
-            return Qfalse;
-        return Qtrue;
+        return RBOOL(xd == yd);
 #else
         long xn, yn;
         if (yi < LONG_MIN || LONG_MAX_as_double <= yi)
             return Qfalse;
         xn = FIX2LONG(x);
         yn = (long)yi;
-        if (xn != yn)
-            return Qfalse;
-        return Qtrue;
+        return RBOOL(xn == yn);
 #endif
     }
     y = rb_dbl2big(yi);
@@ -5440,26 +5438,26 @@ VALUE
 rb_big_cmp(VALUE x, VALUE y)
 {
     if (FIXNUM_P(y)) {
-	x = bigfixize(x);
+        x = bigfixize(x);
         if (FIXNUM_P(x)) {
-	    /* SIGNED_VALUE and Fixnum have same sign-bits, same
-	     * order */
-	    SIGNED_VALUE sx = (SIGNED_VALUE)x, sy = (SIGNED_VALUE)y;
-	    if (sx < sy) return INT2FIX(-1);
-	    return INT2FIX(sx > sy);
+            /* SIGNED_VALUE and Fixnum have same sign-bits, same
+             * order */
+            SIGNED_VALUE sx = (SIGNED_VALUE)x, sy = (SIGNED_VALUE)y;
+            if (sx < sy) return INT2FIX(-1);
+            return INT2FIX(sx > sy);
         }
     }
     else if (RB_BIGNUM_TYPE_P(y)) {
-	if (BIGNUM_SIGN(x) == BIGNUM_SIGN(y)) {
-	    int cmp = bary_cmp(BDIGITS(x), BIGNUM_LEN(x), BDIGITS(y), BIGNUM_LEN(y));
-	    return INT2FIX(BIGNUM_SIGN(x) ? cmp : -cmp);
-	}
+        if (BIGNUM_SIGN(x) == BIGNUM_SIGN(y)) {
+            int cmp = bary_cmp(BDIGITS(x), BIGNUM_LEN(x), BDIGITS(y), BIGNUM_LEN(y));
+            return INT2FIX(BIGNUM_SIGN(x) ? cmp : -cmp);
+        }
     }
     else if (RB_FLOAT_TYPE_P(y)) {
         return rb_integer_float_cmp(x, y);
     }
     else {
-	return rb_num_coerce_cmp(x, y, idCmp);
+        return rb_num_coerce_cmp(x, y, idCmp);
     }
     return INT2FIX(BIGNUM_SIGN(x) ? 1 : -1);
 }
@@ -5478,30 +5476,30 @@ big_op(VALUE x, VALUE y, enum big_op_t op)
     int n;
 
     if (RB_INTEGER_TYPE_P(y)) {
-	rel = rb_big_cmp(x, y);
+        rel = rb_big_cmp(x, y);
     }
     else if (RB_FLOAT_TYPE_P(y)) {
         rel = rb_integer_float_cmp(x, y);
     }
     else {
-	ID id = 0;
-	switch (op) {
-	  case big_op_gt: id = '>'; break;
-	  case big_op_ge: id = idGE; break;
-	  case big_op_lt: id = '<'; break;
-	  case big_op_le: id = idLE; break;
-	}
-	return rb_num_coerce_relop(x, y, id);
+        ID id = 0;
+        switch (op) {
+          case big_op_gt: id = '>'; break;
+          case big_op_ge: id = idGE; break;
+          case big_op_lt: id = '<'; break;
+          case big_op_le: id = idLE; break;
+        }
+        return rb_num_coerce_relop(x, y, id);
     }
 
     if (NIL_P(rel)) return Qfalse;
     n = FIX2INT(rel);
 
     switch (op) {
-	case big_op_gt: return n >  0 ? Qtrue : Qfalse;
-	case big_op_ge: return n >= 0 ? Qtrue : Qfalse;
-	case big_op_lt: return n <  0 ? Qtrue : Qfalse;
-	case big_op_le: return n <= 0 ? Qtrue : Qfalse;
+        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;
 }
@@ -5536,7 +5534,7 @@ rb_big_le(VALUE x, VALUE y)
  *
  *  Returns <code>true</code> only if <i>obj</i> has the same value
  *  as <i>big</i>. Contrast this with Integer#eql?, which requires
- *  <i>obj</i> to be a Integer.
+ *  <i>obj</i> to be an Integer.
  *
  *     68719476736 == 68719476736.0   #=> true
  */
@@ -5545,7 +5543,7 @@ VALUE
 rb_big_eq(VALUE x, VALUE y)
 {
     if (FIXNUM_P(y)) {
-	return bignorm(x) == y ? Qtrue : Qfalse;
+        return RBOOL(bignorm(x) == y);
     }
     else if (RB_BIGNUM_TYPE_P(y)) {
     }
@@ -5553,12 +5551,11 @@ rb_big_eq(VALUE x, VALUE y)
         return rb_integer_float_eq(x, y);
     }
     else {
-	return rb_equal(y, x);
+        return rb_equal(y, x);
     }
     if (BIGNUM_SIGN(x) != BIGNUM_SIGN(y)) return Qfalse;
     if (BIGNUM_LEN(x) != BIGNUM_LEN(y)) return Qfalse;
-    if (MEMCMP(BDIGITS(x),BDIGITS(y),BDIGIT,BIGNUM_LEN(y)) != 0) return Qfalse;
-    return Qtrue;
+    return RBOOL(MEMCMP(BDIGITS(x),BDIGITS(y),BDIGIT,BIGNUM_LEN(y)) == 0);
 }
 
 VALUE
@@ -5567,8 +5564,7 @@ rb_big_eql(VALUE x, VALUE y)
     if (!RB_BIGNUM_TYPE_P(y)) return Qfalse;
     if (BIGNUM_SIGN(x) != BIGNUM_SIGN(y)) return Qfalse;
     if (BIGNUM_LEN(x) != BIGNUM_LEN(y)) return Qfalse;
-    if (MEMCMP(BDIGITS(x),BDIGITS(y),BDIGIT,BIGNUM_LEN(y)) != 0) return Qfalse;
-    return Qtrue;
+    return RBOOL(MEMCMP(BDIGITS(x),BDIGITS(y),BDIGIT,BIGNUM_LEN(y)) == 0);
 }
 
 VALUE
@@ -5662,10 +5658,10 @@ bigsub_int(VALUE x, long y0)
     assert(xn == zn);
     num = (BDIGIT_DBL_SIGNED)xds[0] - y;
     if (xn == 1 && num < 0) {
-	BIGNUM_NEGATE(z);
-	zds[0] = (BDIGIT)-num;
-	RB_GC_GUARD(x);
-	return bignorm(z);
+        BIGNUM_NEGATE(z);
+        zds[0] = (BDIGIT)-num;
+        RB_GC_GUARD(x);
+        return bignorm(z);
     }
     zds[0] = BIGLO(num);
     num = BIGDN(num);
@@ -5677,10 +5673,10 @@ bigsub_int(VALUE x, long y0)
     num = 0;
     for (i=0; i < xn; i++) {
         if (y == 0) goto y_is_zero_x;
-	num += (BDIGIT_DBL_SIGNED)xds[i] - BIGLO(y);
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
-	y = BIGDN(y);
+        num += (BDIGIT_DBL_SIGNED)xds[i] - BIGLO(y);
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
+        y = BIGDN(y);
     }
     for (; i < zn; i++) {
         if (y == 0) goto y_is_zero_z;
@@ -5695,9 +5691,9 @@ bigsub_int(VALUE x, long y0)
     for (; i < xn; i++) {
       y_is_zero_x:
         if (num == 0) goto num_is_zero_x;
-	num += xds[i];
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
+        num += xds[i];
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
     }
 #if SIZEOF_BDIGIT < SIZEOF_LONG
     for (; i < zn; i++) {
@@ -5711,7 +5707,7 @@ bigsub_int(VALUE x, long y0)
 
     for (; i < xn; i++) {
       num_is_zero_x:
-	zds[i] = xds[i];
+        zds[i] = xds[i];
     }
 #if SIZEOF_BDIGIT < SIZEOF_LONG
     for (; i < zn; i++) {
@@ -5725,7 +5721,7 @@ bigsub_int(VALUE x, long y0)
     assert(num == 0 || num == -1);
     if (num < 0) {
         get2comp(z);
-	BIGNUM_NEGATE(z);
+        BIGNUM_NEGATE(z);
     }
     RB_GC_GUARD(x);
     return bignorm(z);
@@ -5768,17 +5764,17 @@ bigadd_int(VALUE x, long y)
     num = 0;
     for (i=0; i < xn; i++) {
         if (y == 0) goto y_is_zero_x;
-	num += (BDIGIT_DBL)xds[i] + BIGLO(y);
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
-	y = BIGDN(y);
+        num += (BDIGIT_DBL)xds[i] + BIGLO(y);
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
+        y = BIGDN(y);
     }
     for (; i < zn; i++) {
         if (y == 0) goto y_is_zero_z;
-	num += BIGLO(y);
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
-	y = BIGDN(y);
+        num += BIGLO(y);
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
+        y = BIGDN(y);
     }
     goto finish;
 
@@ -5787,25 +5783,25 @@ bigadd_int(VALUE x, long y)
     for (;i < xn; i++) {
       y_is_zero_x:
         if (num == 0) goto num_is_zero_x;
-	num += (BDIGIT_DBL)xds[i];
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
+        num += (BDIGIT_DBL)xds[i];
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
     }
     for (; i < zn; i++) {
       y_is_zero_z:
         if (num == 0) goto num_is_zero_z;
-	zds[i] = BIGLO(num);
-	num = BIGDN(num);
+        zds[i] = BIGLO(num);
+        num = BIGDN(num);
     }
     goto finish;
 
     for (;i < xn; i++) {
       num_is_zero_x:
-	zds[i] = xds[i];
+        zds[i] = xds[i];
     }
     for (; i < zn; i++) {
       num_is_zero_z:
-	zds[i] = 0;
+        zds[i] = 0;
     }
     goto finish;
 
@@ -5822,15 +5818,15 @@ bigadd(VALUE x, VALUE y, int sign)
 
     sign = (sign == BIGNUM_SIGN(y));
     if (BIGNUM_SIGN(x) != sign) {
-	if (sign) return bigsub(y, x);
-	return bigsub(x, y);
+        if (sign) return bigsub(y, x);
+        return bigsub(x, y);
     }
 
     if (BIGNUM_LEN(x) > BIGNUM_LEN(y)) {
-	len = BIGNUM_LEN(x) + 1;
+        len = BIGNUM_LEN(x) + 1;
     }
     else {
-	len = BIGNUM_LEN(y) + 1;
+        len = BIGNUM_LEN(y) + 1;
     }
     z = bignew(len, sign);
 
@@ -5847,26 +5843,26 @@ rb_big_plus(VALUE x, VALUE y)
     long n;
 
     if (FIXNUM_P(y)) {
-	n = FIX2LONG(y);
-	if ((n > 0) != BIGNUM_SIGN(x)) {
-	    if (n < 0) {
-		n = -n;
-	    }
-	    return bigsub_int(x, n);
-	}
-	if (n < 0) {
-	    n = -n;
-	}
-	return bigadd_int(x, n);
+        n = FIX2LONG(y);
+        if ((n > 0) != BIGNUM_SIGN(x)) {
+            if (n < 0) {
+                n = -n;
+            }
+            return bigsub_int(x, n);
+        }
+        if (n < 0) {
+            n = -n;
+        }
+        return bigadd_int(x, n);
     }
     else if (RB_BIGNUM_TYPE_P(y)) {
-	return bignorm(bigadd(x, y, 1));
+        return bignorm(bigadd(x, y, 1));
     }
     else if (RB_FLOAT_TYPE_P(y)) {
-	return DBL2NUM(rb_big2dbl(x) + RFLOAT_VALUE(y));
+        return DBL2NUM(rb_big2dbl(x) + RFLOAT_VALUE(y));
     }
     else {
-	return rb_num_coerce_bin(x, y, '+');
+        return rb_num_coerce_bin(x, y, '+');
     }
 }
 
@@ -5876,26 +5872,26 @@ rb_big_minus(VALUE x, VALUE y)
     long n;
 
     if (FIXNUM_P(y)) {
-	n = FIX2LONG(y);
-	if ((n > 0) != BIGNUM_SIGN(x)) {
-	    if (n < 0) {
-		n = -n;
-	    }
-	    return bigadd_int(x, n);
-	}
-	if (n < 0) {
-	    n = -n;
-	}
-	return bigsub_int(x, n);
+        n = FIX2LONG(y);
+        if ((n > 0) != BIGNUM_SIGN(x)) {
+            if (n < 0) {
+                n = -n;
+            }
+            return bigadd_int(x, n);
+        }
+        if (n < 0) {
+            n = -n;
+        }
+        return bigsub_int(x, n);
     }
     else if (RB_BIGNUM_TYPE_P(y)) {
-	return bignorm(bigadd(x, y, 0));
+        return bignorm(bigadd(x, y, 0));
     }
     else if (RB_FLOAT_TYPE_P(y)) {
-	return DBL2NUM(rb_big2dbl(x) - RFLOAT_VALUE(y));
+        return DBL2NUM(rb_big2dbl(x) - RFLOAT_VALUE(y));
     }
     else {
-	return rb_num_coerce_bin(x, y, '-');
+        return rb_num_coerce_bin(x, y, '-');
     }
 }
 
@@ -5954,15 +5950,15 @@ VALUE
 rb_big_mul(VALUE x, VALUE y)
 {
     if (FIXNUM_P(y)) {
-	y = rb_int2big(FIX2LONG(y));
+        y = rb_int2big(FIX2LONG(y));
     }
     else if (RB_BIGNUM_TYPE_P(y)) {
     }
     else if (RB_FLOAT_TYPE_P(y)) {
-	return DBL2NUM(rb_big2dbl(x) * RFLOAT_VALUE(y));
+        return DBL2NUM(rb_big2dbl(x) * RFLOAT_VALUE(y));
     }
     else {
-	return rb_num_coerce_bin(x, y, '*');
+        return rb_num_coerce_bin(x, y, '*');
     }
 
     return bignorm(bigmul0(x, y));
@@ -5989,21 +5985,21 @@ bigdivrem(VALUE x, VALUE y, volatile VALUE *divp, volatile VALUE *modp)
     BARY_TRUNC(xds, xn);
 
     if (xn < yn || (xn == yn && xds[xn - 1] < yds[yn - 1])) {
-	if (divp) *divp = rb_int2big(0);
-	if (modp) *modp = x;
-	return Qnil;
+        if (divp) *divp = rb_int2big(0);
+        if (modp) *modp = x;
+        return Qnil;
     }
     if (yn == 1) {
-	dd = yds[0];
-	z = bignew(xn, BIGNUM_SIGN(x)==BIGNUM_SIGN(y));
-	zds = BDIGITS(z);
+        dd = yds[0];
+        z = bignew(xn, BIGNUM_SIGN(x)==BIGNUM_SIGN(y));
+        zds = BDIGITS(z);
         dd = bigdivrem_single(zds, xds, xn, dd);
-	if (modp) {
-	    *modp = rb_uint2big((uintptr_t)dd);
-	    BIGNUM_SET_SIGN(*modp, BIGNUM_SIGN(x));
-	}
-	if (divp) *divp = z;
-	return Qnil;
+        if (modp) {
+            *modp = rb_uint2big((uintptr_t)dd);
+            BIGNUM_SET_SIGN(*modp, BIGNUM_SIGN(x));
+        }
+        if (divp) *divp = z;
+        return Qnil;
     }
     if (xn == 2 && yn == 2) {
         BDIGIT_DBL x0 = bary2bdigitdbl(xds, 2);
@@ -6068,11 +6064,11 @@ bigdivmod(VALUE x, VALUE y, volatile VALUE *divp, volatile VALUE *modp)
 
     bigdivrem(x, y, divp, &mod);
     if (BIGNUM_SIGN(x) != BIGNUM_SIGN(y) && !BIGZEROP(mod)) {
-	if (divp) *divp = bigadd(*divp, rb_int2big(1), 0);
-	if (modp) *modp = bigadd(mod, y, 1);
+        if (divp) *divp = bigadd(*divp, rb_int2big(1), 0);
+        if (modp) *modp = bigadd(mod, y, 1);
     }
     else if (modp) {
-	*modp = mod;
+        *modp = mod;
     }
 }
 
@@ -6083,25 +6079,25 @@ rb_big_divide(VALUE x, VALUE y, ID op)
     VALUE z;
 
     if (FIXNUM_P(y)) {
-	y = rb_int2big(FIX2LONG(y));
+        y = rb_int2big(FIX2LONG(y));
     }
     else if (RB_BIGNUM_TYPE_P(y)) {
     }
     else if (RB_FLOAT_TYPE_P(y)) {
-	if (op == '/') {
+        if (op == '/') {
             double dx = rb_big2dbl(x);
             return rb_flo_div_flo(DBL2NUM(dx), y);
-	}
-	else {
+        }
+        else {
             VALUE v;
-	    double dy = RFLOAT_VALUE(y);
-	    if (dy == 0.0) rb_num_zerodiv();
+            double dy = RFLOAT_VALUE(y);
+            if (dy == 0.0) rb_num_zerodiv();
             v = rb_big_divide(x, y, '/');
             return rb_dbl2big(RFLOAT_VALUE(v));
-	}
+        }
     }
     else {
-	return rb_num_coerce_bin(x, y, op);
+        return rb_num_coerce_bin(x, y, op);
     }
     bigdivmod(x, y, &z, 0);
 
@@ -6126,10 +6122,10 @@ rb_big_modulo(VALUE x, VALUE y)
     VALUE z;
 
     if (FIXNUM_P(y)) {
-	y = rb_int2big(FIX2LONG(y));
+        y = rb_int2big(FIX2LONG(y));
     }
     else if (!RB_BIGNUM_TYPE_P(y)) {
-	return rb_num_coerce_bin(x, y, '%');
+        return rb_num_coerce_bin(x, y, '%');
     }
     bigdivmod(x, y, 0, &z);
 
@@ -6142,10 +6138,10 @@ rb_big_remainder(VALUE x, VALUE y)
     VALUE z;
 
     if (FIXNUM_P(y)) {
-	y = rb_int2big(FIX2LONG(y));
+        y = rb_int2big(FIX2LONG(y));
     }
     else if (!RB_BIGNUM_TYPE_P(y)) {
-	return rb_num_coerce_bin(x, y, rb_intern("remainder"));
+        return rb_num_coerce_bin(x, y, rb_intern("remainder"));
     }
     bigdivrem(x, y, 0, &z);
 
@@ -6158,7 +6154,7 @@ rb_big_divmod(VALUE x, VALUE y)
     VALUE div, mod;
 
     if (FIXNUM_P(y)) {
-	y = rb_int2big(FIX2LONG(y));
+        y = rb_int2big(FIX2LONG(y));
     }
     else if (!RB_BIGNUM_TYPE_P(y)) {
         return rb_num_coerce_bin(x, y, idDivmod);
@@ -6172,9 +6168,9 @@ static VALUE
 big_shift(VALUE x, long n)
 {
     if (n < 0)
-	return big_lshift(x, 1+(unsigned long)(-(n+1)));
+        return big_lshift(x, 1+(unsigned long)(-(n+1)));
     else if (n > 0)
-	return big_rshift(x, (unsigned long)n);
+        return big_rshift(x, (unsigned long)n);
     return x;
 }
 
@@ -6198,9 +6194,9 @@ big_fdiv(VALUE x, VALUE y, long ey)
     l = ex - ey;
 #if SIZEOF_LONG > SIZEOF_INT
     {
-	/* Visual C++ can't be here */
-	if (l > INT_MAX) return HUGE_VAL;
-	if (l < INT_MIN) return 0.0;
+        /* Visual C++ can't be here */
+        if (l > INT_MAX) return HUGE_VAL;
+        if (l < INT_MIN) return 0.0;
     }
 #endif
     return ldexp(big2dbl(z), (int)l);
@@ -6234,19 +6230,19 @@ rb_big_fdiv_double(VALUE x, VALUE y)
 
     dx = big2dbl(x);
     if (FIXNUM_P(y)) {
-	dy = (double)FIX2LONG(y);
-	if (isinf(dx))
-	    return big_fdiv_int(x, rb_int2big(FIX2LONG(y)));
+        dy = (double)FIX2LONG(y);
+        if (isinf(dx))
+            return big_fdiv_int(x, rb_int2big(FIX2LONG(y)));
     }
     else if (RB_BIGNUM_TYPE_P(y)) {
-	return big_fdiv_int(x, y);
+        return big_fdiv_int(x, y);
     }
     else if (RB_FLOAT_TYPE_P(y)) {
-	dy = RFLOAT_VALUE(y);
-	if (isnan(dy))
-	    return dy;
-	if (isinf(dx))
-	    return big_fdiv_float(x, y);
+        dy = RFLOAT_VALUE(y);
+        if (isnan(dy))
+            return dy;
+        if (isinf(dx))
+            return big_fdiv_float(x, y);
     }
     else {
         return NUM2DBL(rb_num_coerce_bin(x, y, idFdiv));
@@ -6271,20 +6267,20 @@ rb_big_pow(VALUE x, VALUE y)
     if (y == INT2FIX(0)) return INT2FIX(1);
     if (y == INT2FIX(1)) return x;
     if (RB_FLOAT_TYPE_P(y)) {
-	d = RFLOAT_VALUE(y);
-	if ((BIGNUM_NEGATIVE_P(x) && !BIGZEROP(x))) {
+        d = RFLOAT_VALUE(y);
+        if ((BIGNUM_NEGATIVE_P(x) && !BIGZEROP(x))) {
             return rb_dbl_complex_new_polar_pi(pow(-rb_big2dbl(x), d), d);
-	}
+        }
     }
     else if (RB_BIGNUM_TYPE_P(y)) {
-	y = bignorm(y);
-	if (FIXNUM_P(y))
-	    goto again;
-	rb_warn("in a**b, b may be too big");
-	d = rb_big2dbl(y);
+        y = bignorm(y);
+        if (FIXNUM_P(y))
+            goto again;
+        rb_warn("in a**b, b may be too big");
+        d = rb_big2dbl(y);
     }
     else if (FIXNUM_P(y)) {
-	yy = FIX2LONG(y);
+        yy = FIX2LONG(y);
 
         if (yy < 0) {
             x = rb_big_pow(x, LONG2NUM(-yy));
@@ -6293,31 +6289,31 @@ rb_big_pow(VALUE x, VALUE y)
             else
                 return DBL2NUM(1.0 / NUM2DBL(x));
         }
-	else {
-	    VALUE z = 0;
-	    SIGNED_VALUE mask;
+        else {
+            VALUE z = 0;
+            SIGNED_VALUE mask;
             const size_t xbits = rb_absint_numwords(x, 1, NULL);
-	    const size_t BIGLEN_LIMIT = 32*1024*1024;
+            const size_t BIGLEN_LIMIT = 32*1024*1024;
 
-	    if (xbits == (size_t)-1 ||
+            if (xbits == (size_t)-1 ||
                 (xbits > BIGLEN_LIMIT) ||
                 (xbits * yy > BIGLEN_LIMIT)) {
-		rb_warn("in a**b, b may be too big");
-		d = (double)yy;
-	    }
-	    else {
-		for (mask = FIXNUM_MAX + 1; mask; mask >>= 1) {
-		    if (z) z = bigsq(z);
-		    if (yy & mask) {
-			z = z ? bigtrunc(bigmul0(z, x)) : x;
-		    }
-		}
-		return bignorm(z);
-	    }
-	}
+                rb_warn("in a**b, b may be too big");
+                d = (double)yy;
+            }
+            else {
+                for (mask = FIXNUM_MAX + 1; mask; mask >>= 1) {
+                    if (z) z = bigsq(z);
+                    if (yy & mask) {
+                        z = z ? bigtrunc(bigmul0(z, x)) : x;
+                    }
+                }
+                return bignorm(z);
+            }
+        }
     }
     else {
-	return rb_num_coerce_bin(x, y, idPow);
+        return rb_num_coerce_bin(x, y, idPow);
     }
     return DBL2NUM(pow(rb_big2dbl(x), d));
 }
@@ -6337,8 +6333,8 @@ bigand_int(VALUE x, long xn, BDIGIT hibitsx, long y)
     xds = BDIGITS(x);
 #if SIZEOF_BDIGIT >= SIZEOF_LONG
     if (!hibitsy) {
-	y &= xds[0];
-	return LONG2NUM(y);
+        y &= xds[0];
+        return LONG2NUM(y);
     }
 #endif
 
@@ -6367,10 +6363,10 @@ bigand_int(VALUE x, long xn, BDIGIT hibitsx, long y)
     }
 #endif
     for (;i < xn; i++) {
-	zds[i] = xds[i] & hibitsy;
+        zds[i] = xds[i] & hibitsy;
     }
     for (;i < zn; i++) {
-	zds[i] = hibitsx & hibitsy;
+        zds[i] = hibitsx & hibitsy;
     }
     twocomp2abs_bang(z, hibitsx && hibitsy);
     RB_GC_GUARD(x);
@@ -6390,12 +6386,12 @@ rb_big_and(VALUE x, VALUE y)
     long tmpn;
 
     if (!RB_INTEGER_TYPE_P(y)) {
-	return rb_num_coerce_bit(x, y, '&');
+        return rb_num_coerce_bit(x, y, '&');
     }
 
     hibitsx = abs2twocomp(&x, &xn);
     if (FIXNUM_P(y)) {
-	return bigand_int(x, xn, hibitsx, FIX2LONG(y));
+        return bigand_int(x, xn, hibitsx, FIX2LONG(y));
     }
     hibitsy = abs2twocomp(&y, &yn);
     if (xn > yn) {
@@ -6417,10 +6413,10 @@ rb_big_and(VALUE x, VALUE y)
     zds = BDIGITS(z);
 
     for (i=0; i<n1; i++) {
-	zds[i] = ds1[i] & ds2[i];
+        zds[i] = ds1[i] & ds2[i];
     }
     for (; i<n2; i++) {
-	zds[i] = hibits1 & ds2[i];
+        zds[i] = hibits1 & ds2[i];
     }
     twocomp2abs_bang(z, hibits1 && hibits2);
     RB_GC_GUARD(x);
@@ -6509,12 +6505,12 @@ rb_big_or(VALUE x, VALUE y)
     long tmpn;
 
     if (!RB_INTEGER_TYPE_P(y)) {
-	return rb_num_coerce_bit(x, y, '|');
+        return rb_num_coerce_bit(x, y, '|');
     }
 
     hibitsx = abs2twocomp(&x, &xn);
     if (FIXNUM_P(y)) {
-	return bigor_int(x, xn, hibitsx, FIX2LONG(y));
+        return bigor_int(x, xn, hibitsx, FIX2LONG(y));
     }
     hibitsy = abs2twocomp(&y, &yn);
     if (xn > yn) {
@@ -6536,10 +6532,10 @@ rb_big_or(VALUE x, VALUE y)
     zds = BDIGITS(z);
 
     for (i=0; i<n1; i++) {
-	zds[i] = ds1[i] | ds2[i];
+        zds[i] = ds1[i] | ds2[i];
     }
     for (; i<n2; i++) {
-	zds[i] = hibits1 | ds2[i];
+        zds[i] = hibits1 | ds2[i];
     }
     twocomp2abs_bang(z, hibits1 || hibits2);
     RB_GC_GUARD(x);
@@ -6603,12 +6599,12 @@ rb_big_xor(VALUE x, VALUE y)
     long tmpn;
 
     if (!RB_INTEGER_TYPE_P(y)) {
-	return rb_num_coerce_bit(x, y, '^');
+        return rb_num_coerce_bit(x, y, '^');
     }
 
     hibitsx = abs2twocomp(&x, &xn);
     if (FIXNUM_P(y)) {
-	return bigxor_int(x, xn, hibitsx, FIX2LONG(y));
+        return bigxor_int(x, xn, hibitsx, FIX2LONG(y));
     }
     hibitsy = abs2twocomp(&y, &yn);
     if (xn > yn) {
@@ -6627,10 +6623,10 @@ rb_big_xor(VALUE x, VALUE y)
     zds = BDIGITS(z);
 
     for (i=0; i<n1; i++) {
-	zds[i] = ds1[i] ^ ds2[i];
+        zds[i] = ds1[i] ^ ds2[i];
     }
     for (; i<n2; i++) {
-	zds[i] = hibitsx ^ ds2[i];
+        zds[i] = hibitsx ^ ds2[i];
     }
     twocomp2abs_bang(z, (hibits1 ^ hibits2) != 0);
     RB_GC_GUARD(x);
@@ -6646,25 +6642,25 @@ rb_big_lshift(VALUE x, VALUE y)
     int shift_numbits;
 
     for (;;) {
-	if (FIXNUM_P(y)) {
-	    long l = FIX2LONG(y);
+        if (FIXNUM_P(y)) {
+            long l = FIX2LONG(y);
             unsigned long shift;
-	    if (0 <= l) {
-		lshift_p = 1;
+            if (0 <= l) {
+                lshift_p = 1;
                 shift = l;
             }
             else {
-		lshift_p = 0;
-		shift = 1+(unsigned long)(-(l+1));
-	    }
+                lshift_p = 0;
+                shift = 1+(unsigned long)(-(l+1));
+            }
             shift_numbits = (int)(shift & (BITSPERDIG-1));
             shift_numdigits = shift >> bit_length(BITSPERDIG-1);
             return bignorm(big_shift3(x, lshift_p, shift_numdigits, shift_numbits));
-	}
-	else if (RB_BIGNUM_TYPE_P(y)) {
+        }
+        else if (RB_BIGNUM_TYPE_P(y)) {
             return bignorm(big_shift2(x, 1, y));
-	}
-	y = rb_to_int(y);
+        }
+        y = rb_to_int(y);
     }
 }
 
@@ -6676,8 +6672,8 @@ rb_big_rshift(VALUE x, VALUE y)
     int shift_numbits;
 
     for (;;) {
-	if (FIXNUM_P(y)) {
-	    long l = FIX2LONG(y);
+        if (FIXNUM_P(y)) {
+            long l = FIX2LONG(y);
             unsigned long shift;
             if (0 <= l) {
                 lshift_p = 0;
@@ -6685,16 +6681,16 @@ rb_big_rshift(VALUE x, VALUE y)
             }
             else {
                 lshift_p = 1;
-		shift = 1+(unsigned long)(-(l+1));
-	    }
+                shift = 1+(unsigned long)(-(l+1));
+            }
             shift_numbits = (int)(shift & (BITSPERDIG-1));
             shift_numdigits = shift >> bit_length(BITSPERDIG-1);
             return bignorm(big_shift3(x, lshift_p, shift_numdigits, shift_numbits));
-	}
-	else if (RB_BIGNUM_TYPE_P(y)) {
+        }
+        else if (RB_BIGNUM_TYPE_P(y)) {
             return bignorm(big_shift2(x, 0, y));
-	}
-	y = rb_to_int(y);
+        }
+        y = rb_to_int(y);
     }
 }
 
@@ -6708,22 +6704,22 @@ rb_big_aref(VALUE x, VALUE y)
     BDIGIT bit;
 
     if (RB_BIGNUM_TYPE_P(y)) {
-	if (BIGNUM_NEGATIVE_P(y))
-	    return INT2FIX(0);
-	bigtrunc(y);
-	if (BIGSIZE(y) > sizeof(size_t)) {
-	    return BIGNUM_SIGN(x) ? INT2FIX(0) : INT2FIX(1);
-	}
+        if (BIGNUM_NEGATIVE_P(y))
+            return INT2FIX(0);
+        bigtrunc(y);
+        if (BIGSIZE(y) > sizeof(size_t)) {
+            return BIGNUM_SIGN(x) ? INT2FIX(0) : INT2FIX(1);
+        }
 #if SIZEOF_SIZE_T <= SIZEOF_LONG
-	shift = big2ulong(y, "long");
+        shift = big2ulong(y, "long");
 #else
-	shift = big2ull(y, "long long");
+        shift = big2ull(y, "long long");
 #endif
     }
     else {
-	l = NUM2LONG(y);
-	if (l < 0) return INT2FIX(0);
-	shift = (size_t)l;
+        l = NUM2LONG(y);
+        if (l < 0) return INT2FIX(0);
+        shift = (size_t)l;
     }
     s1 = shift/BITSPERDIG;
     s2 = shift%BITSPERDIG;
@@ -6754,14 +6750,15 @@ rb_big_hash(VALUE x)
 
 /*
  * call-seq:
- *   big.coerce(numeric)  ->  array
+ *   int.coerce(numeric)  ->  array
  *
- * Returns an array with both a +numeric+ and a +big+ represented as Bignum
- * objects.
+ * Returns an array with both a +numeric+ and a +int+ represented as
+ * Integer objects or Float objects.
  *
- * This is achieved by converting +numeric+ to a Bignum.
+ * This is achieved by converting +numeric+ to an Integer or a Float.
  *
- * A TypeError is raised if the +numeric+ is not a Fixnum or Bignum type.
+ * A TypeError is raised if the +numeric+ is not an Integer or a Float
+ * type.
  *
  *     (0x3FFFFFFFFFFFFFFF+1).coerce(42)   #=> [42, 4611686018427387904]
  */
@@ -6783,8 +6780,8 @@ VALUE
 rb_big_abs(VALUE x)
 {
     if (BIGNUM_NEGATIVE_P(x)) {
-	x = rb_big_clone(x);
-	BIGNUM_SET_POSITIVE_SIGN(x);
+        x = rb_big_clone(x);
+        BIGNUM_SET_POSITIVE_SIGN(x);
     }
     return x;
 }
@@ -6851,17 +6848,14 @@ rb_big_bit_length(VALUE big)
 VALUE
 rb_big_odd_p(VALUE num)
 {
-    if (BIGNUM_LEN(num) != 0 && BDIGITS(num)[0] & 1) {
-	return Qtrue;
-    }
-    return Qfalse;
+    return RBOOL(BIGNUM_LEN(num) != 0 && BDIGITS(num)[0] & 1);
 }
 
 VALUE
 rb_big_even_p(VALUE num)
 {
     if (BIGNUM_LEN(num) != 0 && BDIGITS(num)[0] & 1) {
-	return Qfalse;
+        return Qfalse;
     }
     return Qtrue;
 }
@@ -6892,21 +6886,21 @@ estimate_initial_sqrt(VALUE *xp, const size_t xn, const BDIGIT *nds, size_t len)
     double f;
 
     if (rshift > 0) {
-	lowbits = (BDIGIT)d & ~(~(BDIGIT)1U << rshift);
-	d >>= rshift;
+        lowbits = (BDIGIT)d & ~(~(BDIGIT)1U << rshift);
+        d >>= rshift;
     }
     else if (rshift < 0) {
-	d <<= -rshift;
-	d |= nds[len-dbl_per_bdig-1] >> (BITSPERDIG+rshift);
+        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;
+        if (lowbits || (lowbits = !bary_zero_p(nds, len-dbl_per_bdig)))
+            ++d;
     }
     else {
-	lowbits = 1;
+        lowbits = 1;
     }
     rshift /= 2;
     rshift += (2-(len&1))*BITSPERDIG/2;
@@ -6938,37 +6932,35 @@ rb_big_isqrt(VALUE n)
     BDIGIT *xds;
 
     if (len <= 2) {
-	BDIGIT sq = rb_bdigit_dbl_isqrt(bary2bdigitdbl(nds, len));
+        BDIGIT sq = rb_bdigit_dbl_isqrt(bary2bdigitdbl(nds, len));
 #if SIZEOF_BDIGIT > SIZEOF_LONG
-	return ULL2NUM(sq);
+        return ULL2NUM(sq);
 #else
-	return ULONG2NUM(sq);
+        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);
-	}
-	rb_big_realloc(t, 0);
-	rb_gc_force_recycle(t);
+        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);
+        }
     }
     RBASIC_SET_CLASS_RAW(x, rb_cInteger);
     return x;
 }
 
-#ifdef USE_GMP
+#if USE_GMP
 static void
 bary_powm_gmp(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT *yds, size_t yn, const BDIGIT *mds, size_t mn)
 {
@@ -6994,7 +6986,7 @@ bary_powm_gmp(BDIGIT *zds, size_t zn, const BDIGIT *xds, size_t xn, const BDIGIT
 static VALUE
 int_pow_tmp3(VALUE x, VALUE y, VALUE m, int nega_flg)
 {
-#ifdef USE_GMP
+#if USE_GMP
     VALUE z;
     size_t xn, yn, mn, zn;
 
@@ -7160,6 +7152,7 @@ rb_int_powm(int const argc, VALUE * const argv, VALUE const num)
             long const half_val = (long)HALF_LONG_MSB;
             long const mm = FIX2LONG(m);
             if (!mm) rb_num_zerodiv();
+            if (mm == 1) return INT2FIX(0);
             if (mm <= half_val) {
                 return int_pow_tmp1(rb_int_modulo(a, m), b, mm, nega_flg);
             }
@@ -7169,6 +7162,7 @@ rb_int_powm(int const argc, VALUE * const argv, VALUE const num)
         }
         else {
             if (rb_bigzero_p(m)) rb_num_zerodiv();
+            if (bignorm(m) == INT2FIX(1)) return INT2FIX(0);
             return int_pow_tmp3(rb_int_modulo(a, m), b, m, nega_flg);
         }
     }
@@ -7196,13 +7190,9 @@ rb_int_powm(int const argc, VALUE * const argv, VALUE const num)
 void
 Init_Bignum(void)
 {
-    /* An obsolete class, use Integer */
-    rb_define_const(rb_cObject, "Bignum", rb_cInteger);
-    rb_deprecate_constant(rb_cObject, "Bignum");
-
     rb_define_method(rb_cInteger, "coerce", rb_int_coerce, 1);
 
-#ifdef USE_GMP
+#if USE_GMP
     /* The version of loaded GMP. */
     rb_define_const(rb_cInteger, "GMP_VERSION", rb_sprintf("GMP %s", gmp_version));
 #endif
diff --git a/bin/bundle b/bin/bundle
deleted file mode 100755
index 1a0b06b005..0000000000
--- a/bin/bundle
+++ /dev/null
@@ -1,27 +0,0 @@
-#!/usr/bin/env ruby
-#
-# This file was generated by RubyGems.
-#
-# The application 'bundler' is installed as part of a gem, and
-# this file is here to facilitate running it.
-#
-
-require 'rubygems'
-
-version = ">= 0.a"
-
-str = ARGV.first
-if str
-  str = str.b[/\A_(.*)_\z/, 1]
-  if str and Gem::Version.correct?(str)
-    version = str
-    ARGV.shift
-  end
-end
-
-if Gem.respond_to?(:activate_bin_path)
-load Gem.activate_bin_path('bundler', 'bundle', version)
-else
-gem "bundler", version
-load Gem.bin_path("bundler", "bundle", version)
-end
diff --git a/bin/bundler b/bin/bundler
deleted file mode 100755
index e15eb39ed7..0000000000
--- a/bin/bundler
+++ /dev/null
@@ -1,27 +0,0 @@
-#!/usr/bin/env ruby
-#
-# This file was generated by RubyGems.
-#
-# The application 'bundler' is installed as part of a gem, and
-# this file is here to facilitate running it.
-#
-
-require 'rubygems'
-
-version = ">= 0.a"
-
-str = ARGV.first
-if str
-  str = str.b[/\A_(.*)_\z/, 1]
-  if str and Gem::Version.correct?(str)
-    version = str
-    ARGV.shift
-  end
-end
-
-if Gem.respond_to?(:activate_bin_path)
-load Gem.activate_bin_path('bundler', 'bundler', version)
-else
-gem "bundler", version
-load Gem.bin_path("bundler", "bundler", version)
-end
diff --git a/bin/erb b/bin/erb
deleted file mode 100755
index 2435224fe1..0000000000
--- a/bin/erb
+++ /dev/null
@@ -1,176 +0,0 @@
-#!/usr/bin/env ruby
-# Tiny eRuby --- ERB2
-# Copyright (c) 1999-2000,2002 Masatoshi SEKI
-# You can redistribute it and/or modify it under the same terms as Ruby.
-
-require 'erb'
-
-class ERB
-  module Main
-    def ARGV.switch
-      return nil if self.empty?
-      arg = self.shift
-      return nil if arg == '--'
-      case arg
-      when /\A-(.)(.*)/
-        if $1 == '-'
-          arg, @maybe_arg = arg.split(/=/, 2)
-          return arg
-        end
-        raise 'unknown switch "-"' if $2[0] == ?- and $1 != 'T'
-        if $2.size > 0
-          self.unshift "-#{$2}"
-          @maybe_arg = $2
-        else
-          @maybe_arg = nil
-        end
-        "-#{$1}"
-      when /\A(\w+)=/
-        arg
-      else
-        self.unshift arg
-        nil
-      end
-    end
-
-    def ARGV.req_arg
-      (@maybe_arg || self.shift || raise('missing argument')).tap {
-        @maybe_arg = nil
-      }
-    end
-
-    def trim_mode_opt(trim_mode, disable_percent)
-      return trim_mode if disable_percent
-      case trim_mode
-      when 0
-        return '%'
-      when 1
-        return '%>'
-      when 2
-        return '%<>'
-      when '-'
-        return '%-'
-      end
-    end
-    module_function :trim_mode_opt
-
-    def run(factory=ERB)
-      trim_mode = 0
-      disable_percent = false
-      variables = {}
-      begin
-        while switch = ARGV.switch
-          case switch
-          when '-x'                        # ruby source
-            output = true
-          when '-n'                        # line number
-            number = true
-          when '-v'                        # verbose
-            $VERBOSE = true
-          when '--version'                 # version
-            STDERR.puts factory.version
-            exit
-          when '-d', '--debug'             # debug
-            $DEBUG = true
-          when '-r'                        # require
-            require ARGV.req_arg
-          when '-S'                        # security level
-            warn 'warning: -S option of erb command is deprecated. Please do not use this.'
-            arg = ARGV.req_arg
-            raise "invalid safe_level #{arg.dump}" unless arg =~ /\A[0-1]\z/
-            safe_level = arg.to_i
-          when '-T'                        # trim mode
-            arg = ARGV.req_arg
-            if arg == '-'
-              trim_mode = arg
-              next
-            end
-            raise "invalid trim mode #{arg.dump}" unless arg =~ /\A[0-2]\z/
-            trim_mode = arg.to_i
-          when '-E', '--encoding'
-            arg = ARGV.req_arg
-            set_encoding(*arg.split(/:/, 2))
-          when '-U'
-            set_encoding(Encoding::UTF_8, Encoding::UTF_8)
-          when '-P'
-            disable_percent = true
-          when '--help'
-            raise "print this help"
-          when /\A-/
-            raise "unknown switch #{switch.dump}"
-          else
-            var, val = *switch.split('=', 2)
-            (variables ||= {})[var] = val
-          end
-        end
-      rescue                               # usage
-        STDERR.puts $!.to_s
-        STDERR.puts File.basename($0) +
-          " [switches] [var=value...] [inputfile]"
-        STDERR.puts <<EOU
-  -x               print ruby script
-  -n               print ruby script with line number
-  -v               enable verbose mode
-  -d               set $DEBUG to true
-  -r library       load a library
-  -E ex[:in]       set default external/internal encodings
-  -U               set default encoding to UTF-8
-  -T trim_mode     specify trim_mode (0..2, -)
-  -P               disable ruby code evaluation for lines beginning with %
-  var=value        set variable
-EOU
-        exit 1
-      end
-
-      $<.set_encoding(Encoding::UTF_8, nil)
-      src = $<.read
-      filename = $FILENAME
-      exit 2 unless src
-      trim = trim_mode_opt(trim_mode, disable_percent)
-      if safe_level.nil?
-        erb = factory.new(src, trim_mode: trim)
-      else
-        # [deprecated] This will be removed at Ruby 2.7.
-        erb = factory.new(src, safe_level, trim_mode: trim)
-      end
-      erb.filename = filename
-      if output
-        if number
-          erb.src.each_line.with_index do |line, l|
-            puts "%3d %s"%[l+1, line]
-          end
-        else
-          puts erb.src
-        end
-      else
-        bind = TOPLEVEL_BINDING
-        if variables
-          enc = erb.encoding
-          for var, val in variables do
-            val = val.encode(enc) if val
-            bind.local_variable_set(var, val)
-          end
-        end
-        erb.run(bind)
-      end
-    end
-    module_function :run
-
-    def set_encoding(extern, intern = nil)
-      verbose, $VERBOSE = $VERBOSE, nil
-      Encoding.default_external = extern unless extern.nil? || extern == ""
-      Encoding.default_internal = intern unless intern.nil? || intern == ""
-      [$stdin, $stdout, $stderr].each do |io|
-        io.set_encoding(extern, intern)
-      end
-    ensure
-      $VERBOSE = verbose
-    end
-    module_function :set_encoding
-    class << self; private :set_encoding; end
-  end
-end
-
-if __FILE__ == $0
-  ERB::Main.run
-end
diff --git a/bin/gem b/bin/gem
index a4ec754abb..1c16ea7ddd 100755
--- a/bin/gem
+++ b/bin/gem
@@ -5,21 +5,6 @@
 # See LICENSE.txt for permissions.
 #++
 
-require 'rubygems'
-require 'rubygems/gem_runner'
-require 'rubygems/exceptions'
-
-required_version = Gem::Requirement.new ">= 1.8.7"
-
-unless required_version.satisfied_by? Gem.ruby_version then
-  abort "Expected Ruby Version #{required_version}, is #{Gem.ruby_version}"
-end
-
-args = ARGV.clone
-
-begin
-  Gem::GemRunner.new.run args
-rescue Gem::SystemExitException => e
-  exit e.exit_code
-end
+require "rubygems/gem_runner"
 
+Gem::GemRunner.new.run ARGV.clone
diff --git a/bin/irb b/bin/irb
deleted file mode 100755
index ae6d358c9d..0000000000
--- a/bin/irb
+++ /dev/null
@@ -1,27 +0,0 @@
-#!/usr/bin/env ruby
-#
-# This file was generated by RubyGems.
-#
-# The application 'irb' is installed as part of a gem, and
-# this file is here to facilitate running it.
-#
-
-require 'rubygems'
-
-version = ">= 0.a"
-
-str = ARGV.first
-if str
-  str = str.b[/\A_(.*)_\z/, 1]
-  if str and Gem::Version.correct?(str)
-    version = str
-    ARGV.shift
-  end
-end
-
-if Gem.respond_to?(:activate_bin_path)
-load Gem.activate_bin_path('irb', 'irb', version)
-else
-gem "irb", version
-load Gem.bin_path("irb", "irb", version)
-end
diff --git a/bin/racc b/bin/racc
deleted file mode 100755
index 3ddac532b4..0000000000
--- a/bin/racc
+++ /dev/null
@@ -1,27 +0,0 @@
-#!/usr/bin/env ruby
-#
-# This file was generated by RubyGems.
-#
-# The application 'racc' is installed as part of a gem, and
-# this file is here to facilitate running it.
-#
-
-require 'rubygems'
-
-version = ">= 0.a"
-
-if ARGV.first
-  str = ARGV.first
-  str = str.dup.force_encoding("BINARY") if str.respond_to? :force_encoding
-  if str =~ /\A_(.*)_\z/ and Gem::Version.correct?($1) then
-    version = $1
-    ARGV.shift
-  end
-end
-
-if Gem.respond_to?(:activate_bin_path)
-load Gem.activate_bin_path('racc', 'racc', version)
-else
-gem "racc", version
-load Gem.bin_path("racc", "racc", version)
-end
diff --git a/bin/rdoc b/bin/rdoc
deleted file mode 100755
index 8fa948cddb..0000000000
--- a/bin/rdoc
+++ /dev/null
@@ -1,27 +0,0 @@
-#!/usr/bin/env ruby
-#
-# This file was generated by RubyGems.
-#
-# The application 'rdoc' is installed as part of a gem, and
-# this file is here to facilitate running it.
-#
-
-require 'rubygems'
-
-version = ">= 0.a"
-
-str = ARGV.first
-if str
-  str = str.b[/\A_(.*)_\z/, 1]
-  if str and Gem::Version.correct?(str)
-    version = str
-    ARGV.shift
-  end
-end
-
-if Gem.respond_to?(:activate_bin_path)
-load Gem.activate_bin_path('rdoc', 'rdoc', version)
-else
-gem "rdoc", version
-load Gem.bin_path("rdoc", "rdoc", version)
-end
diff --git a/bin/ri b/bin/ri
deleted file mode 100755
index 0cc2f73bb6..0000000000
--- a/bin/ri
+++ /dev/null
@@ -1,27 +0,0 @@
-#!/usr/bin/env ruby
-#
-# This file was generated by RubyGems.
-#
-# The application 'rdoc' is installed as part of a gem, and
-# this file is here to facilitate running it.
-#
-
-require 'rubygems'
-
-version = ">= 0.a"
-
-str = ARGV.first
-if str
-  str = str.b[/\A_(.*)_\z/, 1]
-  if str and Gem::Version.correct?(str)
-    version = str
-    ARGV.shift
-  end
-end
-
-if Gem.respond_to?(:activate_bin_path)
-load Gem.activate_bin_path('rdoc', 'ri', version)
-else
-gem "rdoc", version
-load Gem.bin_path("rdoc", "ri", version)
-end
diff --git a/bootstraptest/runner.rb b/bootstraptest/runner.rb
index 56b4b12230..f9b3e919b8 100755
--- a/bootstraptest/runner.rb
+++ b/bootstraptest/runner.rb
@@ -8,6 +8,8 @@
 # Never use Ruby extensions in this file.
 # Maintain Ruby 1.8 compatibility for now
 
+$start_time = Time.now
+
 begin
   require 'fileutils'
   require 'tmpdir'
@@ -58,24 +60,114 @@ if !Dir.respond_to?(:mktmpdir)
   end
 end
 
+# Configuration
+bt = Struct.new(:ruby,
+                :verbose,
+                :color,
+                :tty,
+                :quiet,
+                :wn,
+                :progress,
+                :progress_bs,
+                :passed,
+                :failed,
+                :reset,
+                :columns,
+                :window_width,
+                :width,
+                :indent,
+                :platform,
+                )
+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
+      if /(?:\A|\s)--jobserver-(?:auth|fds)=(?:(\d+),(\d+)|fifo:((?:\\.|\S)+))/ =~ ENV.delete("MAKEFLAGS")
+        begin
+          if fifo = $3
+            fifo.gsub!(/\\(?=.)/, '')
+            r = File.open(fifo, IO::RDONLY|IO::NONBLOCK|IO::BINARY)
+            w = File.open(fifo, IO::WRONLY|IO::NONBLOCK|IO::BINARY)
+          else
+            r = IO.for_fd($1.to_i(10), "rb", autoclose: false)
+            w = IO.for_fd($2.to_i(10), "wb", autoclose: false)
+          end
+        rescue => e
+          r.close if r
+        else
+          r.close_on_exec = true
+          w.close_on_exec = true
+          tokens = r.read_nonblock(wn > 0 ? wn : 1024, exception: false)
+          r.close
+          if String === tokens
+            tokens.freeze
+            auth = w
+            w = nil
+            at_exit {auth << tokens; auth.close}
+            wn = tokens.size + 1
+          else
+            w.close
+            wn = 1
+          end
+        end
+      end
+      if wn <= 0
+        require 'etc'
+        wn = [Etc.nprocessors / 2, 1].max
+      end
+    end
+    super wn
+  end
+end.new
+
+BT_STATE = Struct.new(:count, :error).new
+
 def main
-  @ruby = File.expand_path('miniruby')
-  @verbose = false
+  BT.ruby = File.expand_path('miniruby')
+  BT.verbose = false
   $VERBOSE = false
   $stress = false
-  @color = nil
-  @tty = nil
-  @quiet = false
+  BT.color = nil
+  BT.tty = nil
+  BT.quiet = false
+  # BT.wn = 1
   dir = nil
   quiet = false
   tests = nil
   ARGV.delete_if {|arg|
     case arg
     when /\A--ruby=(.*)/
-      @ruby = $1
-      @ruby.gsub!(/^([^ ]*)/){File.expand_path($1)}
-      @ruby.gsub!(/(\s+-I\s*)((?!(?:\.\/)*-(?:\s|\z))\S+)/){$1+File.expand_path($2)}
-      @ruby.gsub!(/(\s+-r\s*)(\.\.?\/\S+)/){$1+File.expand_path($2)}
+      ruby = $1
+      ruby.gsub!(/^([^ ]*)/){File.expand_path($1)}
+      ruby.gsub!(/(\s+-I\s*)((?!(?:\.\/)*-(?:\s|\z))\S+)/){$1+File.expand_path($2)}
+      ruby.gsub!(/(\s+-r\s*)(\.\.?\/\S+)/){$1+File.expand_path($2)}
+      BT.ruby = ruby
       true
     when /\A--sets=(.*)/
       tests = Dir.glob("#{File.dirname($0)}/test_{#{$1}}*.rb").sort
@@ -88,18 +180,23 @@ def main
       $stress = true
     when /\A--color(?:=(?:always|(auto)|(never)|(.*)))?\z/
       warn "unknown --color argument: #$3" if $3
-      @color = $1 ? nil : !$2
+      BT.color = color = $1 ? nil : !$2
       true
     when /\A--tty(=(?:yes|(no)|(.*)))?\z/
       warn "unknown --tty argument: #$3" if $3
-      @tty = !$1 || !$2
+      BT.tty = !$1 || !$2
       true
     when /\A(-q|--q(uiet))\z/
       quiet = true
-      @quiet = true
+      BT.quiet = true
+      true
+    when /\A-j(\d+)?/
+      BT.wn = $1.to_i
       true
     when /\A(-v|--v(erbose))\z/
-      @verbose = true
+      BT.verbose = true
+      BT.quiet = false
+      true
     when /\A(-h|--h(elp)?)\z/
       puts(<<-End)
 Usage: #{File.basename($0, '.*')} --ruby=PATH [--sets=NAME,NAME,...]
@@ -121,22 +218,23 @@ End
     end
   }
   if tests and not ARGV.empty?
-    $stderr.puts "--tests and arguments are exclusive"
-    exit false
+    abort "--sets and arguments are exclusive"
   end
   tests ||= ARGV
   tests = Dir.glob("#{File.dirname($0)}/test_*.rb").sort if tests.empty?
   pathes = tests.map {|path| File.expand_path(path) }
 
-  @progress = %w[- \\ | /]
-  @progress_bs = "\b" * @progress[0].size
-  @tty = $stderr.tty? if @tty.nil?
-  case @color
+  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
-    @color = @tty && /dumb/ !~ ENV["TERM"]
+    BT.color = BT.tty && /dumb/ !~ ENV["TERM"]
   end
-  @tty &&= !@verbose
-  if @color
+  BT.tty &&= !BT.verbose
+  if BT.color
     # dircolors-like style
     colors = (colors = ENV['TEST_COLORS']) ? Hash[colors.scan(/(\w+)=([^:\n]*)/)] : {}
     begin
@@ -145,14 +243,16 @@ End
       end
     rescue
     end
-    @passed = "\e[;#{colors["pass"] || "32"}m"
-    @failed = "\e[;#{colors["fail"] || "31"}m"
-    @reset = "\e[m"
+    BT.passed = "\e[;#{colors["pass"] || "32"}m"
+    BT.failed = "\e[;#{colors["fail"] || "31"}m"
+    BT.reset = "\e[m"
   else
-    @passed = @failed = @reset = ""
+    BT.passed = BT.failed = BT.reset = ""
   end
+  target_version = `#{BT.ruby} -v`.chomp
+  BT.platform = target_version[/\[(.*)\]\z/, 1]
   unless quiet
-    puts Time.now
+    puts $start_time
     if defined?(RUBY_DESCRIPTION)
       puts "Driver is #{RUBY_DESCRIPTION}"
     elsif defined?(RUBY_PATCHLEVEL)
@@ -160,265 +260,469 @@ End
     else
       puts "Driver is ruby #{RUBY_VERSION} (#{RUBY_RELEASE_DATE}) [#{RUBY_PLATFORM}]"
     end
-    puts "Target is #{`#{@ruby} -v`.chomp}"
+    puts "Target is #{target_version}"
     puts
     $stdout.flush
   end
 
-  in_temporary_working_directory(dir) {
+  in_temporary_working_directory(dir) do
     exec_test pathes
-  }
+  end
 end
 
 def erase(e = true)
-  if e and @columns > 0 and @tty and !@verbose
+  if e and BT.columns > 0 and BT.tty and !BT.verbose
     "\e[1K\r"
   else
     ""
   end
 end
 
-def exec_test(pathes)
-  @count = 0
-  @error = 0
-  @errbuf = []
-  @location = nil
-  @columns = 0
-  @width = pathes.map {|path| File.basename(path).size}.max + 2
+def load_test pathes
   pathes.each do |path|
-    @basename = File.basename(path)
-    $stderr.printf("%s%-*s ", erase(@quiet), @width, @basename)
-    $stderr.flush
-    @columns = @width + 1
-    $stderr.puts if @verbose
-    count = @count
-    error = @error
     load File.expand_path(path)
-    if @tty
-      if @error == error
-        msg = "PASS #{@count-count}"
-        @columns += msg.size - 1
-        $stderr.print "#{@progress_bs}#{@passed}#{msg}#{@reset}"
+  end
+end
+
+def concurrent_exec_test
+  aq = Queue.new
+  rq = Queue.new
+
+  ts = BT.wn.times.map do
+    Thread.new do
+      while as = aq.pop
+        as.call
+        rq << as
+      end
+    ensure
+      rq << nil
+    end
+  end
+
+  Assertion.all.to_a.shuffle.each do |path, assertions|
+    assertions.each do |as|
+      aq << as
+    end
+  end
+
+  BT.indent = 1
+  aq.close
+  i = 1
+  term_wn = 0
+  begin
+    while BT.wn != term_wn
+      if r = rq.pop
+        case
+        when BT.quiet
+        when BT.tty
+          $stderr.print "#{BT.progress_bs}#{BT.progress[(i+=1) % BT.progress.size]}"
+        else
+          BT.putc '.'
+        end
       else
-        msg = "FAIL #{@error-error}/#{@count-count}"
-        $stderr.print "#{@progress_bs}#{@failed}#{msg}#{@reset}"
-        @columns = 0
+        term_wn += 1
+      end
+    end
+  ensure
+    ts.each(&:kill)
+    ts.each(&:join)
+  end
+end
+
+def exec_test(pathes)
+  # setup
+  load_test pathes
+  BT_STATE.count = 0
+  BT_STATE.error = 0
+  BT.columns = 0
+  BT.width = pathes.map {|path| File.basename(path).size}.max + 2
+
+  # execute tests
+  if BT.wn > 1
+    concurrent_exec_test
+  else
+    prev_basename = nil
+    Assertion.all.each do |basename, assertions|
+      if !BT.quiet && basename != prev_basename
+        prev_basename = basename
+        $stderr.printf("%s%-*s ", erase(BT.quiet), BT.width, basename)
+        $stderr.flush
+      end
+      BT.columns = BT.width + 1
+      $stderr.puts if BT.verbose
+      count = BT_STATE.count
+      error = BT_STATE.error
+
+      assertions.each do |assertion|
+        BT_STATE.count += 1
+        assertion.call
+      end
+
+      if BT.tty
+        if BT_STATE.error == error
+          msg = "PASS #{BT_STATE.count-count}"
+          BT.columns += msg.size - 1
+          $stderr.print "#{BT.progress_bs}#{BT.passed}#{msg}#{BT.reset}" unless BT.quiet
+        else
+          msg = "FAIL #{BT_STATE.error-error}/#{BT_STATE.count-count}"
+          $stderr.print "#{BT.progress_bs}#{BT.failed}#{msg}#{BT.reset}"
+          BT.columns = 0
+        end
       end
+      $stderr.puts if !BT.quiet and (BT.tty or BT_STATE.error == error)
     end
-    $stderr.puts unless @quiet and @tty and @error == error
   end
-  $stderr.print(erase) if @quiet
-  @errbuf.each do |msg|
+
+  # show results
+  unless BT.quiet
+    $stderr.puts(erase)
+
+    sec = Time.now - $start_time
+    $stderr.puts "Finished in #{'%.2f' % sec} sec\n\n" if Assertion.count > 0
+  end
+
+  Assertion.errbuf.each do |msg|
     $stderr.puts msg
   end
-  if @error == 0
-    if @count == 0
-      $stderr.puts "No tests, no problem"
+
+  out = BT.quiet ? $stdout : $stderr
+
+  if BT_STATE.error == 0
+    if Assertion.count == 0
+      out.puts "No tests, no problem" unless BT.quiet
     else
-      $stderr.puts "#{@passed}PASS#{@reset} all #{@count} tests"
+      out.puts "#{BT.passed}PASS#{BT.reset} all #{Assertion.count} tests"
     end
-    exit true
+    true
   else
-    $stderr.puts "#{@failed}FAIL#{@reset} #{@error}/#{@count} tests failed"
-    exit false
+    $stderr.puts "#{BT.failed}FAIL#{BT.reset} #{BT_STATE.error}/#{BT_STATE.count} tests failed"
+    false
   end
 end
 
-def show_progress(message = '')
-  if @verbose
-    $stderr.print "\##{@count} #{@location} "
-  elsif @tty
-    $stderr.print "#{@progress_bs}#{@progress[@count % @progress.size]}"
-  end
-  t = Time.now if @verbose
-  faildesc, errout = with_stderr {yield}
-  t = Time.now - t if @verbose
-  if !faildesc
-    if @tty
-      $stderr.print "#{@progress_bs}#{@progress[@count % @progress.size]}"
-    elsif @verbose
-      $stderr.printf(". %.3f\n", t)
+def target_platform
+  BT.platform or RUBY_PLATFORM
+end
+
+class Assertion < Struct.new(:src, :path, :lineno, :proc)
+  @count = 0
+  @all = Hash.new{|h, k| h[k] = []}
+  @errbuf = []
+
+  class << self
+    attr_reader :count, :errbuf
+
+    def all
+      @all
+    end
+
+    def add as
+      @all[as.path] << as
+      as.id = (@count += 1)
+    end
+  end
+
+  attr_accessor :id
+  attr_reader :err, :category
+
+  def initialize(*args)
+    super
+    self.class.add self
+    @category = self.path.match(/test_(.+)\.rb/)[1]
+  end
+
+  def call
+    self.proc.call self
+  end
+
+  def assert_check(message = '', opt = '', **argh)
+    show_progress(message) {
+      result = get_result_string(opt, **argh)
+      yield(result)
+    }
+  end
+
+  def with_stderr
+    out = err = nil
+    r, w = IO.pipe
+    @err = w
+    err_reader = Thread.new{ r.read }
+
+    begin
+      out = yield
+    ensure
+      w.close
+      err = err_reader.value
+      r.close rescue nil
+    end
+
+    return out, err
+  end
+
+  def show_error(msg, additional_message)
+    msg = "#{BT.failed}\##{self.id} #{self.path}:#{self.lineno}#{BT.reset}: #{msg}  #{additional_message}"
+    if BT.tty
+      $stderr.puts "#{erase}#{msg}"
     else
-      $stderr.print '.'
+      Assertion.errbuf << msg
     end
-  else
-    $stderr.print "#{@failed}F"
-    $stderr.printf(" %.3f", t) if @verbose
-    $stderr.print @reset
-    $stderr.puts if @verbose
-    error faildesc, message
-    unless errout.empty?
-      $stderr.print "#{@failed}stderr output is not empty#{@reset}\n", adjust_indent(errout)
+    BT_STATE.error += 1
+  end
+
+
+  def show_progress(message = '')
+    if BT.quiet || BT.wn > 1
+      # do nothing
+    elsif BT.verbose
+      $stderr.print "\##{@id} #{self.path}:#{self.lineno} "
+    elsif BT.tty
+      $stderr.print "#{BT.progress_bs}#{BT.progress[BT_STATE.count % BT.progress.size]}"
+    end
+
+    t = Time.now if BT.verbose
+    faildesc, errout = with_stderr {yield}
+    t = Time.now - t if BT.verbose
+
+    if !faildesc
+      # success
+      if BT.quiet || BT.wn > 1
+        # do nothing
+      elsif BT.tty
+        $stderr.print "#{BT.progress_bs}#{BT.progress[BT_STATE.count % BT.progress.size]}"
+      elsif BT.verbose
+        $stderr.printf(". %.3f\n", t)
+      else
+        BT.putc '.'
+      end
+    else
+      $stderr.print "#{BT.failed}F"
+      $stderr.printf(" %.3f", t) if BT.verbose
+      $stderr.print BT.reset
+      $stderr.puts if BT.verbose
+      show_error faildesc, message
+      unless errout.empty?
+        $stderr.print "#{BT.failed}stderr output is not empty#{BT.reset}\n", adjust_indent(errout)
+      end
+
+      if BT.tty and !BT.verbose and BT.wn == 1
+        $stderr.printf("%-*s%s", BT.width, path, BT.progress[BT_STATE.count % BT.progress.size])
+      end
     end
-    if @tty and !@verbose
-      $stderr.printf("%-*s%s", @width, @basename, @progress[@count % @progress.size])
+  rescue Interrupt
+    $stderr.puts "\##{@id} #{path}:#{lineno}"
+    raise
+  rescue Exception => err
+    $stderr.print 'E'
+    $stderr.puts if BT.verbose
+    show_error err.message, message
+  ensure
+    begin
+      check_coredump
+    rescue CoreDumpError => err
+      $stderr.print 'E'
+      $stderr.puts if BT.verbose
+      show_error err.message, message
+      cleanup_coredump
     end
   end
-rescue Interrupt
-  $stderr.puts "\##{@count} #{@location}"
-  raise
-rescue Exception => err
-  $stderr.print 'E'
-  $stderr.puts if @verbose
-  error err.message, message
-end
 
-def show_limit(testsrc, opt = '', **argh)
-  result = get_result_string(testsrc, opt, **argh)
-  if @tty and @verbose
-    $stderr.puts ".{#@reset}\n#{erase}#{result}"
-  else
-    @errbuf.push result
+  def get_result_string(opt = '', **argh)
+    if BT.ruby
+      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 }
+      ensure
+        raise Interrupt if $? and $?.signaled? && $?.termsig == Signal.list["INT"]
+
+        begin
+          Process.kill :KILL, pid
+        rescue Errno::ESRCH
+          # OK
+        end
+      end
+    else
+      eval(src).to_s
+    end
+  end
+
+  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)"
+    }
+    filename
   end
 end
 
-def assert_check(testsrc, message = '', opt = '', **argh)
-  show_progress(message) {
-    result = get_result_string(testsrc, opt, **argh)
-    check_coredump
-    yield(result)
-  }
+def add_assertion src, pr
+  loc = caller_locations(2, 1).first
+  lineno = loc.lineno
+  path = File.basename(loc.path)
+
+  Assertion.new(src, path, lineno, pr)
 end
 
 def assert_equal(expected, testsrc, message = '', opt = '', **argh)
-  newtest
-  assert_check(testsrc, message, opt, **argh) {|result|
-    if expected == result
-      nil
-    else
-      desc = "#{result.inspect} (expected #{expected.inspect})"
-      pretty(testsrc, desc, result)
-    end
-  }
+  add_assertion testsrc, -> as do
+    as.assert_check(message, opt, **argh) {|result|
+      if expected == result
+        nil
+      else
+        desc = "#{result.inspect} (expected #{expected.inspect})"
+        pretty(testsrc, desc, result)
+      end
+    }
+  end
 end
 
 def assert_match(expected_pattern, testsrc, message = '')
-  newtest
-  assert_check(testsrc, message) {|result|
-    if expected_pattern =~ result
-      nil
-    else
-      desc = "#{expected_pattern.inspect} expected to be =~\n#{result.inspect}"
-      pretty(testsrc, desc, result)
-    end
-  }
+  add_assertion testsrc, -> as do
+    as.assert_check(message) {|result|
+      if expected_pattern =~ result
+        nil
+      else
+        desc = "#{expected_pattern.inspect} expected to be =~\n#{result.inspect}"
+        pretty(testsrc, desc, result)
+      end
+    }
+  end
 end
 
 def assert_not_match(unexpected_pattern, testsrc, message = '')
-  newtest
-  assert_check(testsrc, message) {|result|
-    if unexpected_pattern !~ result
-      nil
-    else
-      desc = "#{unexpected_pattern.inspect} expected to be !~\n#{result.inspect}"
-      pretty(testsrc, desc, result)
-    end
-  }
+  add_assertion testsrc, -> as do
+    as.assert_check(message) {|result|
+      if unexpected_pattern !~ result
+        nil
+      else
+        desc = "#{unexpected_pattern.inspect} expected to be !~\n#{result.inspect}"
+        pretty(testsrc, desc, result)
+      end
+    }
+  end
 end
 
 def assert_valid_syntax(testsrc, message = '')
-  newtest
-  assert_check(testsrc, message, '-c') {|result|
-    result if /Syntax OK/ !~ result
-  }
+  add_assertion testsrc, -> as do
+    as.assert_check(message, '-c') {|result|
+      result if /Syntax OK/ !~ result
+    }
+  end
 end
 
 def assert_normal_exit(testsrc, *rest, timeout: nil, **opt)
-  newtest
-  message, ignore_signals = rest
-  message ||= ''
-  show_progress(message) {
-    faildesc = nil
-    filename = make_srcfile(testsrc)
-    old_stderr = $stderr.dup
-    timeout_signaled = false
-    begin
-      $stderr.reopen("assert_normal_exit.log", "w")
-      io = IO.popen("#{@ruby} -W0 #{filename}")
-      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
-      $stderr.reopen(old_stderr)
-      old_stderr.close
-    end
-    if status && status.signaled?
-      signo = status.termsig
-      signame = Signal.list.invert[signo]
-      unless ignore_signals and ignore_signals.include?(signame)
-        sigdesc = "signal #{signo}"
-        if signame
-          sigdesc = "SIG#{signame} (#{sigdesc})"
-        end
-        if timeout_signaled
-          sigdesc << " (timeout)"
+  add_assertion testsrc, -> as do
+    message, ignore_signals = rest
+    message ||= ''
+    as.show_progress(message) {
+      faildesc = nil
+      filename = as.make_srcfile
+      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
-        faildesc = pretty(testsrc, "killed by #{sigdesc}", nil)
-        stderr_log = File.read("assert_normal_exit.log")
-        if !stderr_log.empty?
-          faildesc << "\n" if /\n\z/ !~ faildesc
-          stderr_log << "\n" if /\n\z/ !~ stderr_log
-          stderr_log.gsub!(/^.*\n/) { '| ' + $& }
-          faildesc << stderr_log
+        status = th.value
+      ensure
+        err.close
+      end
+      if status && status.signaled?
+        signo = status.termsig
+        signame = Signal.list.invert[signo]
+        unless ignore_signals and ignore_signals.include?(signame)
+          sigdesc = "signal #{signo}"
+          if signame
+            sigdesc = "SIG#{signame} (#{sigdesc})"
+          end
+          if timeout_signaled
+            sigdesc << " (timeout)"
+          end
+          faildesc = pretty(testsrc, "killed by #{sigdesc}", nil)
+          stderr_log = File.read(logfile)
+          if !stderr_log.empty?
+            faildesc << "\n" if /\n\z/ !~ faildesc
+            stderr_log << "\n" if /\n\z/ !~ stderr_log
+            stderr_log.gsub!(/^.*\n/) { '| ' + $& }
+            faildesc << stderr_log
+          end
         end
       end
-    end
-    faildesc
-  }
+      faildesc
+    }
+  end
 end
 
 def assert_finish(timeout_seconds, testsrc, message = '')
-  if RubyVM.const_defined? :MJIT
-    timeout_seconds *= 3 if RubyVM::MJIT.enabled? # for --jit-wait
-  end
-  newtest
-  show_progress(message) {
-    faildesc = nil
-    filename = make_srcfile(testsrc)
-    io = IO.popen("#{@ruby} -W0 #{filename}")
-    pid = io.pid
-    waited = false
-    tlimit = Time.now + timeout_seconds
-    diff = timeout_seconds
-    while diff > 0
-      if Process.waitpid pid, Process::WNOHANG
-        waited = true
-        break
-      end
-      if io.respond_to?(:read_nonblock)
-        if IO.select([io], nil, nil, diff)
-          begin
-            io.read_nonblock(1024)
-          rescue Errno::EAGAIN, IO::WaitReadable, EOFError
-            break
-          end while true
+  add_assertion testsrc, -> as do
+    if defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled? # for --jit-wait
+      timeout_seconds *= 3
+    end
+
+    as.show_progress(message) {
+      faildesc = nil
+      filename = as.make_srcfile
+      io = IO.popen("#{BT.ruby} -W0 #{filename}", err: as.err)
+      pid = io.pid
+      waited = false
+      tlimit = Time.now + timeout_seconds
+      diff = timeout_seconds
+      while diff > 0
+        if Process.waitpid pid, Process::WNOHANG
+          waited = true
+          break
         end
-      else
-        sleep 0.1
+        if io.respond_to?(:read_nonblock)
+          if IO.select([io], nil, nil, diff)
+            begin
+              io.read_nonblock(1024)
+            rescue Errno::EAGAIN, IO::WaitReadable, EOFError
+              break
+            end while true
+          end
+        else
+          sleep 0.1
+        end
+        diff = tlimit - Time.now
       end
-      diff = tlimit - Time.now
-    end
-    if !waited
-      Process.kill(:KILL, pid)
-      Process.waitpid pid
-      faildesc = pretty(testsrc, "not finished in #{timeout_seconds} seconds", nil)
-    end
-    io.close
-    faildesc
-  }
+      if !waited
+        Process.kill(:KILL, pid)
+        Process.waitpid pid
+        faildesc = pretty(testsrc, "not finished in #{timeout_seconds} seconds", nil)
+      end
+      io.close
+      faildesc
+    }
+  end
 end
 
 def flunk(message = '')
-  newtest
-  show_progress('') { message }
+  add_assertion '', -> as do
+    as.show_progress('') { message }
+  end
+end
+
+def show_limit(testsrc, opt = '', **argh)
+  return if BT.quiet
+
+  add_assertion testsrc, -> as do
+    result = as.get_result_string(opt, **argh)
+    Assertion.errbuf << result
+  end
 end
 
 def pretty(src, desc, result)
@@ -436,67 +740,6 @@ def untabify(str)
   str.gsub(/^\t+/) {' ' * (8 * $&.size) }
 end
 
-def make_srcfile(src, frozen_string_literal: nil)
-  filename = 'bootstraptest.tmp.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; #{src}; end)"
-  }
-  filename
-end
-
-def get_result_string(src, opt = '', **argh)
-  if @ruby
-    filename = make_srcfile(src, **argh)
-    begin
-      `#{@ruby} -W0 #{opt} #{filename}`
-    ensure
-      raise Interrupt if $? and $?.signaled? && $?.termsig == Signal.list["INT"]
-      raise CoreDumpError, "core dumped" if $? and $?.coredump?
-    end
-  else
-    eval(src).to_s
-  end
-end
-
-def with_stderr
-  out = err = nil
-  begin
-    r, w = IO.pipe
-    stderr = $stderr.dup
-    $stderr.reopen(w)
-    w.close
-    reader = Thread.start {r.read}
-    begin
-      out = yield
-    ensure
-      $stderr.reopen(stderr)
-      err = reader.value
-    end
-  ensure
-    w.close rescue nil
-    r.close rescue nil
-  end
-  return out, err
-end
-
-def newtest
-  @location = File.basename(caller(2).first)
-  @count += 1
-  cleanup_coredump
-end
-
-def error(msg, additional_message)
-  msg = "#{@failed}\##{@count} #{@location}#{@reset}: #{msg}  #{additional_message}"
-  if @tty
-    $stderr.puts "#{erase}#{msg}"
-  else
-    @errbuf.push msg
-  end
-  @error += 1
-end
-
 def in_temporary_working_directory(dir)
   if dir
     Dir.mkdir dir
@@ -513,18 +756,32 @@ def in_temporary_working_directory(dir)
 end
 
 def cleanup_coredump
-  FileUtils.rm_f 'core'
+  if File.file?('core')
+    require 'time'
+    Dir.glob('/tmp/bootstraptest-core.*').each do |f|
+      if Time.now - File.mtime(f) > 7 * 24 * 60 * 60 # 7 days
+        warn "Deleting an old core file: #{f}"
+        FileUtils.rm(f)
+      end
+    end
+    core_path = "/tmp/bootstraptest-core.#{Time.now.utc.iso8601}"
+    warn "A core file is found. Saving it at: #{core_path.dump}"
+    FileUtils.mv('core', core_path)
+    cmd = ['gdb', BT.ruby, '-c', core_path, '-ex', 'bt', '-batch']
+    p cmd # debugging why it's not working
+    system(*cmd)
+  end
   FileUtils.rm_f Dir.glob('core.*')
-  FileUtils.rm_f @ruby+'.stackdump' if @ruby
+  FileUtils.rm_f BT.ruby+'.stackdump' if BT.ruby
 end
 
 class CoreDumpError < StandardError; end
 
 def check_coredump
   if File.file?('core') or not Dir.glob('core.*').empty? or
-      (@ruby and File.exist?(@ruby+'.stackdump'))
+      (BT.ruby and File.exist?(BT.ruby+'.stackdump'))
     raise CoreDumpError, "core dumped"
   end
 end
 
-main
+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 a9f8e6dacd..9e0850bc52 100644
--- a/bootstraptest/test_autoload.rb
+++ b/bootstraptest/test_autoload.rb
@@ -1,7 +1,7 @@
 assert_equal 'ok', %q{
-  File.unlink('zzz.rb') if File.file?('zzz.rb')
+  File.unlink('zzz1.rb') if File.file?('zzz1.rb')
   instance_eval do
-    autoload :ZZZ, './zzz.rb'
+    autoload :ZZZ, './zzz1.rb'
     begin
       ZZZ
     rescue LoadError
@@ -11,9 +11,9 @@ assert_equal 'ok', %q{
 }, '[ruby-dev:43816]'
 
 assert_equal 'ok', %q{
-  open('zzz.rb', 'w') {|f| f.puts '' }
+  open('zzz2.rb', 'w') {|f| f.puts '' }
   instance_eval do
-    autoload :ZZZ, './zzz.rb'
+    autoload :ZZZ, './zzz2.rb'
     begin
       ZZZ
     rescue NameError
@@ -23,29 +23,29 @@ assert_equal 'ok', %q{
 }, '[ruby-dev:43816]'
 
 assert_equal 'ok', %q{
-  open('zzz.rb', 'w') {|f| f.puts 'class ZZZ; def self.ok;:ok;end;end'}
+  open('zzz3.rb', 'w') {|f| f.puts 'class ZZZ; def self.ok;:ok;end;end'}
   instance_eval do
-    autoload :ZZZ, './zzz.rb'
+    autoload :ZZZ, './zzz3.rb'
     ZZZ.ok
   end
 }, '[ruby-dev:43816]'
 
 assert_equal 'ok', %q{
-  open("zzz.rb", "w") {|f| f.puts "class ZZZ; def self.ok;:ok;end;end"}
-  autoload :ZZZ, "./zzz.rb"
+  open("zzz4.rb", "w") {|f| f.puts "class ZZZ; def self.ok;:ok;end;end"}
+  autoload :ZZZ, "./zzz4.rb"
   ZZZ.ok
 }
 
 assert_equal 'ok', %q{
-  open("zzz.rb", "w") {|f| f.puts "class ZZZ; def self.ok;:ok;end;end"}
-  autoload :ZZZ, "./zzz.rb"
-  require "./zzz.rb"
+  open("zzz5.rb", "w") {|f| f.puts "class ZZZ; def self.ok;:ok;end;end"}
+  autoload :ZZZ, "./zzz5.rb"
+  require "./zzz5.rb"
   ZZZ.ok
 }
 
 assert_equal 'okok', %q{
-  open("zzz.rb", "w") {|f| f.puts "class ZZZ; def self.ok;:ok;end;end"}
-  autoload :ZZZ, "./zzz.rb"
+  open("zzz6.rb", "w") {|f| f.puts "class ZZZ; def self.ok;:ok;end;end"}
+  autoload :ZZZ, "./zzz6.rb"
   t1 = Thread.new {ZZZ.ok}
   t2 = Thread.new {ZZZ.ok}
   [t1.value, t2.value].join
@@ -60,9 +60,9 @@ assert_finish 5, %q{
 }, '[ruby-core:21696]'
 
 assert_equal 'A::C', %q{
-  open("zzz.rb", "w") {}
+  open("zzz7.rb", "w") {}
   class A
-    autoload :C, "./zzz"
+    autoload :C, "./zzz7"
     class C
     end
     C
diff --git a/bootstraptest/test_constant_cache.rb b/bootstraptest/test_constant_cache.rb
new file mode 100644
index 0000000000..1fa83256ed
--- /dev/null
+++ b/bootstraptest/test_constant_cache.rb
@@ -0,0 +1,187 @@
+# Constant lookup is cached.
+assert_equal '1', %q{
+  CONST = 1
+
+  def const
+    CONST
+  end
+
+  const
+  const
+}
+
+# Invalidate when a constant is set.
+assert_equal '2', %q{
+  CONST = 1
+
+  def const
+    CONST
+  end
+
+  const
+
+  CONST = 2
+
+  const
+}
+
+# Invalidate when a constant of the same name is set.
+assert_equal '1', %q{
+  CONST = 1
+
+  def const
+    CONST
+  end
+
+  const
+
+  class Container
+    CONST = 2
+  end
+
+  const
+}
+
+# Invalidate when a constant is removed.
+assert_equal 'missing', %q{
+  class Container
+    CONST = 1
+
+    def const
+      CONST
+    end
+
+    def self.const_missing(name)
+      'missing'
+    end
+
+    new.const
+    remove_const :CONST
+  end
+
+  Container.new.const
+}
+
+# Invalidate when a constant's visibility changes.
+assert_equal 'missing', %q{
+  class Container
+    CONST = 1
+
+    def self.const_missing(name)
+      'missing'
+    end
+  end
+
+  def const
+    Container::CONST
+  end
+
+  const
+
+  Container.private_constant :CONST
+
+  const
+}
+
+# Invalidate when a constant's visibility changes even if the call to the
+# visibility change method fails.
+assert_equal 'missing', %q{
+  class Container
+    CONST1 = 1
+
+    def self.const_missing(name)
+      'missing'
+    end
+  end
+
+  def const1
+    Container::CONST1
+  end
+
+  const1
+
+  begin
+    Container.private_constant :CONST1, :CONST2
+  rescue NameError
+  end
+
+  const1
+}
+
+# Invalidate when a module is included.
+assert_equal 'INCLUDE', %q{
+  module Include
+    CONST = :INCLUDE
+  end
+
+  class Parent
+    CONST = :PARENT
+  end
+
+  class Child < Parent
+    def const
+      CONST
+    end
+
+    new.const
+
+    include Include
+  end
+
+  Child.new.const
+}
+
+# Invalidate when const_missing is hit.
+assert_equal '2', %q{
+  module Container
+    Foo = 1
+    Bar = 2
+
+    class << self
+      attr_accessor :count
+
+      def const_missing(name)
+        @count += 1
+        @count == 1 ? Foo : Bar
+      end
+    end
+
+    @count = 0
+  end
+
+  def const
+    Container::Baz
+  end
+
+  const
+  const
+}
+
+# Invalidate when the iseq gets cleaned up.
+assert_equal '2', %q{
+  CONSTANT = 1
+
+  iseq = RubyVM::InstructionSequence.compile(<<~RUBY)
+    CONSTANT
+  RUBY
+
+  iseq.eval
+  iseq = nil
+
+  GC.start
+  CONSTANT = 2
+}
+
+# Invalidate when the iseq gets cleaned up even if it was never in the cache.
+assert_equal '2', %q{
+  CONSTANT = 1
+
+  iseq = RubyVM::InstructionSequence.compile(<<~RUBY)
+    CONSTANT
+  RUBY
+
+  iseq = nil
+
+  GC.start
+  CONSTANT = 2
+}
diff --git a/bootstraptest/test_eval.rb b/bootstraptest/test_eval.rb
index 5d2593c306..a9f389c673 100644
--- a/bootstraptest/test_eval.rb
+++ b/bootstraptest/test_eval.rb
@@ -116,6 +116,33 @@ assert_equal %q{1}, %q{
     Const
   }
 }
+assert_equal %q{1}, %q{
+  class TrueClass
+    Const = 1
+  end
+  true.instance_eval %{
+    Const
+  }
+}
+assert_equal %q{[:Const]}, %q{
+  mod = Module.new
+  mod.instance_eval %{
+    Const = 1
+  }
+  raise if defined?(Module::Const)
+  mod.singleton_class.constants
+}
+assert_equal %q{can't define singleton}, %q{
+  begin
+    123.instance_eval %{
+      Const = 1
+    }
+    "bad"
+  rescue TypeError => e
+    raise "bad" if defined?(Integer::Const)
+    e.message
+  end
+}
 assert_equal %q{top}, %q{
   Const = :top
   class C
@@ -191,7 +218,7 @@ assert_equal %q{[10, main]}, %q{
 
 %w[break next redo].each do |keyword|
   assert_match %r"Can't escape from eval with #{keyword}\b", %{
-    STDERR.reopen(STDOUT)
+    $stderr = STDOUT
     begin
       eval "0 rescue #{keyword}"
     rescue SyntaxError => e
@@ -201,7 +228,7 @@ assert_equal %q{[10, main]}, %q{
 end
 
 assert_normal_exit %q{
-  STDERR.reopen(STDOUT)
+  $stderr = STDOUT
   class Foo
      def self.add_method
        class_eval("def some-bad-name; puts 'hello' unless @some_variable.some_function(''); end")
diff --git a/bootstraptest/test_fiber.rb b/bootstraptest/test_fiber.rb
index 35e1bf6851..2614dd13bf 100644
--- a/bootstraptest/test_fiber.rb
+++ b/bootstraptest/test_fiber.rb
@@ -19,12 +19,12 @@ assert_equal %q{ok}, %q{
 }
 
 assert_equal %q{ok}, %q{
-  10_000.times.collect{Fiber.new{}}
+  100.times.collect{Fiber.new{}}
   :ok
 }
 
 assert_equal %q{ok}, %q{
-  fibers = 100.times.collect{Fiber.new{Fiber.yield}}
+  fibers = 1000.times.collect{Fiber.new{Fiber.yield}}
   fibers.each(&:resume)
   fibers.each(&:resume)
   :ok
diff --git a/bootstraptest/test_insns.rb b/bootstraptest/test_insns.rb
index 8addbf7b83..91fba9b011 100644
--- a/bootstraptest/test_insns.rb
+++ b/bootstraptest/test_insns.rb
@@ -86,11 +86,8 @@ tests = [
   [ 'putobject',            %q{ /(?<x>x)/ =~ "x"; x == "x" }, ],
 
   [ 'putspecialobject',         %q{ {//=>true}[//] }, ],
-  [ 'putiseq',                  %q{ -> { true }.() }, ],
   [ 'putstring',                %q{ "true" }, ],
   [ 'tostring / concatstrings', %q{ "#{true}" }, ],
-  [ 'freezestring',             %q{ "#{true}" }, fsl, ],
-  [ 'freezestring',             %q{ "#{true}" }, '-d', fsl, ],
   [ 'toregexp',                 %q{ /#{true}/ =~ "true" && $~ }, ],
   [ 'intern',                   %q{ :"#{true}" }, ],
 
@@ -123,6 +120,7 @@ tests = [
   [ 'dup',     %q{ x = y = true; x }, ],
   [ 'dupn',    %q{ Object::X ||= true }, ],
   [ 'reverse', %q{ q, (w, e), r = 1, [2, 3], 4; e == 3 }, ],
+  [ 'swap',    %q{ !!defined?([[]]) }, ],
   [ 'swap',    <<-'},', ],      # {
     x = [[false, true]]
     for i, j in x               # here
@@ -387,14 +385,13 @@ tests = [
   [ 'opt_empty_p', %q{ ''.empty? }, ],
   [ 'opt_empty_p', %q{ [].empty? }, ],
   [ 'opt_empty_p', %q{ {}.empty? }, ],
-  [ 'opt_empty_p', %q{ Queue.new.empty? }, ],
+  [ 'opt_empty_p', %q{ Thread::Queue.new.empty? }, ],
 
   [ 'opt_succ',  %q{ 1.succ == 2 }, ],
   if defined? $FIXNUM_MAX then
     [ 'opt_succ',%Q{ #{ $FIXNUM_MAX }.succ == #{ $FIXNUM_MAX + 1 } }, ]
   end,
   [ 'opt_succ',  %q{ '1'.succ == '2' }, ],
-  [ 'opt_succ',  %q{ x = Time.at(0); x.succ == Time.at(1) }, ],
 
   [ 'opt_not',  %q{ ! false }, ],
   [ 'opt_neq', <<-'},', ],       # {
diff --git a/bootstraptest/test_io.rb b/bootstraptest/test_io.rb
index 89c00d0b88..666e5a011b 100644
--- a/bootstraptest/test_io.rb
+++ b/bootstraptest/test_io.rb
@@ -1,3 +1,4 @@
+/freebsd/ =~ RUBY_PLATFORM or
 assert_finish 5, %q{
   r, w = IO.pipe
   t1 = Thread.new { r.sysread(1) }
@@ -30,7 +31,8 @@ assert_finish 10, %q{
   end
 }, '[ruby-dev:32566]'
 
-assert_finish 1, %q{
+/freebsd/ =~ RUBY_PLATFORM or
+assert_finish 5, %q{
   r, w = IO.pipe
   Thread.new {
     w << "ab"
@@ -83,6 +85,7 @@ assert_normal_exit %q{
   ARGF.set_encoding "foo"
 }
 
+/freebsd/ =~ RUBY_PLATFORM or
 10.times do
   assert_normal_exit %q{
     at_exit { p :foo }
diff --git a/bootstraptest/test_jump.rb b/bootstraptest/test_jump.rb
index 18a2737ea3..d07c47a56d 100644
--- a/bootstraptest/test_jump.rb
+++ b/bootstraptest/test_jump.rb
@@ -147,7 +147,7 @@ assert_equal %q{131}, %q{
   }
 }
 assert_match %r{Invalid retry}, %q{
-STDERR.reopen(STDOUT)
+$stderr = STDOUT
 begin
   eval %q{
     1.times{
@@ -297,7 +297,7 @@ assert_equal "true", %q{
 }, '[ruby-core:21379]'
 
 assert_match %r{Invalid yield}, %q{
-STDERR.reopen(STDOUT)
+$stderr = STDOUT
 begin
   eval %q{
     class Object
diff --git a/bootstraptest/test_literal.rb b/bootstraptest/test_literal.rb
index 9b3c10d519..a0d4ee08c6 100644
--- a/bootstraptest/test_literal.rb
+++ b/bootstraptest/test_literal.rb
@@ -65,8 +65,11 @@ assert_equal ':a3c',            ':"a#{1+2}c".inspect'
 assert_equal 'Symbol',          ':"a#{1+2}c".class'
 
 # xstring
-assert_equal "foo\n",           %q(`echo foo`)
-assert_equal "foo\n",           %q(s = "foo"; `echo #{s}`)
+# WASI doesn't support spawning a new process for now.
+if /wasi/ !~ target_platform
+  assert_equal "foo\n",           %q(`echo foo`)
+  assert_equal "foo\n",           %q(s = "foo"; `echo #{s}`)
+end
 
 # regexp
 assert_equal '',                '//.source'
diff --git a/bootstraptest/test_method.rb b/bootstraptest/test_method.rb
index 3462aa9434..04c9eb2d11 100644
--- a/bootstraptest/test_method.rb
+++ b/bootstraptest/test_method.rb
@@ -22,7 +22,7 @@ assert_match /\Awrong number of arguments \(.*\b0\b.* 1\)\z/, %q{
 }
 
 # default argument
-assert_equal '1',       'def m(x=1) x end; m()'
+assert_equal '1',       'def m(x=1) x end; m();'
 assert_equal '1',       'def m(x=7) x end; m(1)'
 assert_equal '1',       'def m(a,x=1) x end; m(7)'
 assert_equal '1',       'def m(a,x=7) x end; m(7,1)'
diff --git a/bootstraptest/test_ractor.rb b/bootstraptest/test_ractor.rb
new file mode 100644
index 0000000000..67e66b03ee
--- /dev/null
+++ b/bootstraptest/test_ractor.rb
@@ -0,0 +1,1628 @@
+# Ractor.current returns a current ractor
+assert_equal 'Ractor', %q{
+  Ractor.current.class
+}
+
+# Ractor.new returns new Ractor
+assert_equal 'Ractor', %q{
+  Ractor.new{}.class
+}
+
+# Ractor.allocate is not supported
+assert_equal "[:ok, :ok]", %q{
+  rs = []
+  begin
+    Ractor.allocate
+  rescue => e
+    rs << :ok if e.message == 'allocator undefined for Ractor'
+  end
+
+  begin
+    Ractor.new{}.dup
+  rescue
+    rs << :ok if e.message == 'allocator undefined for Ractor'
+  end
+
+  rs
+}
+
+# A Ractor can have a name
+assert_equal 'test-name', %q{
+  r = Ractor.new name: 'test-name' do
+  end
+  r.name
+}
+
+# If Ractor doesn't have a name, Ractor#name returns nil.
+assert_equal 'nil', %q{
+  r = Ractor.new do
+  end
+  r.name.inspect
+}
+
+# Raises exceptions if initialize with an invalid name
+assert_equal 'ok', %q{
+  begin
+    r = Ractor.new(name: [{}]) {}
+  rescue TypeError => e
+    'ok'
+  end
+}
+
+# Ractor.new must call with a block
+assert_equal "must be called with a block", %q{
+  begin
+    Ractor.new
+  rescue ArgumentError => e
+    e.message
+  end
+}
+
+# Ractor#inspect
+# Return only id and status for main ractor
+assert_equal "#<Ractor:#1 running>", %q{
+  Ractor.current.inspect
+}
+
+# Return id, loc, and status for no-name ractor
+assert_match /^#<Ractor:#([^ ]*?) .+:[0-9]+ terminated>$/, %q{
+  r = Ractor.new { '' }
+  r.take
+  sleep 0.1 until r.inspect =~ /terminated/
+  r.inspect
+}
+
+# Return id, name, loc, and status for named ractor
+assert_match /^#<Ractor:#([^ ]*?) Test Ractor .+:[0-9]+ terminated>$/, %q{
+  r = Ractor.new(name: 'Test Ractor') { '' }
+  r.take
+  sleep 0.1 until r.inspect =~ /terminated/
+  r.inspect
+}
+
+# A return value of a Ractor block will be a message from the Ractor.
+assert_equal 'ok', %q{
+  # join
+  r = Ractor.new do
+    'ok'
+  end
+  r.take
+}
+
+# Passed arguments to Ractor.new will be a block parameter
+# The values are passed with Ractor-communication pass.
+assert_equal 'ok', %q{
+  # ping-pong with arg
+  r = Ractor.new 'ok' do |msg|
+    msg
+  end
+  r.take
+}
+
+# Pass multiple arguments to Ractor.new
+assert_equal 'ok', %q{
+  # ping-pong with two args
+  r =  Ractor.new 'ping', 'pong' do |msg, msg2|
+    [msg, msg2]
+  end
+  'ok' if r.take == ['ping', 'pong']
+}
+
+# Ractor#send passes an object with copy to a Ractor
+# and Ractor.receive in the Ractor block can receive the passed value.
+assert_equal 'ok', %q{
+  r = Ractor.new do
+    msg = Ractor.receive
+  end
+  r.send 'ok'
+  r.take
+}
+
+# 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
+}
+
+# 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
+  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 #
+}
+
+# dtoa race condition
+assert_equal '[:ok, :ok, :ok]', %q{
+  n = 3
+  n.times.map{
+    Ractor.new{
+      10_000.times{ rand.to_s }
+      :ok
+    }
+  }.map(&:take)
+}
+
+# Ractor.make_shareable 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] } }
+
+  Ractor.make_shareable(closure).call
+}
+
+# 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
+  end
+
+  Ractor.make_shareable(closure).call
+}
+
+# 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
+  end
+  r.take
+}
+
+###
+###
+# Ractor still has several memory corruption so skip huge number of tests
+if ENV['GITHUB_WORKFLOW'] &&
+   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]
+assert_equal 'ok', %q{
+  # select 1
+  r1 = Ractor.new{'r1'}
+  r, obj = Ractor.select(r1)
+  'ok' if r == r1 and obj == 'r1'
+}
+
+# Ractor.select from two ractors.
+assert_equal '["r1", "r2"]', %q{
+  # select 2
+  r1 = Ractor.new{'r1'}
+  r2 = Ractor.new{'r2'}
+  rs = [r1, r2]
+  as = []
+  r, obj = Ractor.select(*rs)
+  rs.delete(r)
+  as << obj
+  r, obj = Ractor.select(*rs)
+  as << obj
+  as.sort #=> ["r1", "r2"]
+}
+
+# Ractor.select from multiple ractors.
+assert_equal 30.times.map { 'ok' }.to_s, %q{
+  def test n
+    rs = (1..n).map do |i|
+      Ractor.new(i) do |i|
+        "r#{i}"
+      end
+    end
+    as = []
+    all_rs = rs.dup
+
+    n.times{
+      r, obj = Ractor.select(*rs)
+      as << [r, obj]
+      rs.delete(r)
+    }
+
+    if as.map{|r, o| r.object_id}.sort == all_rs.map{|r| r.object_id}.sort &&
+       as.map{|r, o| o}.sort == (1..n).map{|i| "r#{i}"}.sort
+      'ok'
+    else
+      'ng'
+    end
+  end
+
+  30.times.map{|i|
+    test i
+  }
+} unless ENV['RUN_OPTS'] =~ /--mjit-call-threshold=5/ || # This always fails with --mjit-wait --mjit-call-threshold=5
+  (ENV.key?('TRAVIS') && ENV['TRAVIS_CPU_ARCH'] == 'arm64') || # https://bugs.ruby-lang.org/issues/17878
+  true # too flaky everywhere http://ci.rvm.jp/results/trunk@ruby-sp1/4321096
+
+# Exception for empty select
+assert_match /specify at least one ractor/, %q{
+  begin
+    Ractor.select
+  rescue ArgumentError => e
+    e.message
+  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
+  sleep 0.1 until r.inspect =~ /terminated/
+
+  begin
+    r.send(1)
+  rescue Ractor::ClosedError
+    'ok'
+  else
+    'ng'
+  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]
+assert_equal 'err', %q{
+  Ractor.new{
+    t = Thread.current
+    begin
+      Thread.new{ t.raise "err" }.join
+    rescue => e
+      e.message
+    end
+  }.take
+}
+
+# Killed Ractor's thread yields nil
+assert_equal 'nil', %q{
+  Ractor.new{
+    t = Thread.current
+    Thread.new{ t.kill }.join
+  }.take.inspect #=> nil
+}
+
+# Ractor.yield raises Ractor::ClosedError when outgoing port is closed.
+assert_equal 'ok', %q{
+  r = Ractor.new Ractor.current do |main|
+    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
+
+  begin
+    r.send(1)
+  rescue Ractor::ClosedError
+    'ok'
+  else
+    'ng'
+  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
+}
+
+# a ractor with closed outgoing port should terminate
+assert_equal 'ok', %q{
+  Ractor.new do
+    close_outgoing
+  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
+  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
+} unless /mswin/ =~ RUBY_PLATFORM # randomly hangs on mswin https://github.com/ruby/ruby/actions/runs/3753871445/jobs/6377551069#step:20:131
+
+# 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
+  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
+    end
+  end
+
+  RN = 10
+  RN.times.map{|i|
+    Ractor.new pipe, i do |pipe, i|
+      pipe << i
+    end
+  }
+  RN.times.map{
+    pipe.take
+  }.sort
+}
+
+# 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
+  end
+  begin
+    r.take
+  rescue Ractor::RemoteError => e
+    [e.cause.class,   #=> RuntimeError
+     e.cause.message, #=> 'ok'
+     e.ractor == r]   #=> true
+  end
+}
+
+# threads in a ractor will killed
+assert_equal '{:ok=>3}', %q{
+  Ractor.new Ractor.current do |main|
+    q = Thread::Queue.new
+    Thread.new do
+      q << true
+      loop{}
+    ensure
+      main << :ok
+    end
+
+    Thread.new do
+      q << true
+      while true
+      end
+    ensure
+      main << :ok
+    end
+
+    Thread.new do
+      q << true
+      sleep 1
+    ensure
+      main << :ok
+    end
+
+    # wait for the start of all threads
+    3.times{q.pop}
+  end
+
+  3.times.map{Ractor.receive}.tally
+}
+
+# unshareable object are copied
+assert_equal 'false', %q{
+  obj = 'str'.dup
+  r = Ractor.new obj do |msg|
+    msg.object_id
+  end
+
+  obj.object_id == r.take
+}
+
+# To copy the object, now Marshal#dump is used
+assert_equal "allocator undefined for Thread", %q{
+  obj = Thread.new{}
+  begin
+    r = Ractor.new obj do |msg|
+      msg
+    end
+  rescue TypeError => e
+    e.message #=> no _dump_data is defined for class Thread
+  else
+    'ng'
+  end
+}
+
+# send shareable and unshareable objects
+assert_equal "ok", %q{
+  echo_ractor = Ractor.new do
+    loop do
+      v = Ractor.receive
+      Ractor.yield v
+    end
+  end
+
+  class C; end
+  module M; end
+  S = Struct.new(:a, :b, :c, :d)
+
+  shareable_objects = [
+    true,
+    false,
+    nil,
+    1,
+    1.1,    # Float
+    1+2r,   # Rational
+    3+4i,   # Complex
+    2**128, # Bignum
+    :sym,   # Symbol
+    'xyzzy'.to_sym, # dynamic symbol
+    'frozen'.freeze, # frozen String
+    /regexp/, # regexp literal
+    /reg{true}exp/.freeze, # frozen dregexp
+    [1, 2].freeze,   # frozen Array which only refers to shareable
+    {a: 1}.freeze,   # frozen Hash which only refers to shareable
+    [{a: 1}.freeze, 'str'.freeze].freeze, # nested frozen container
+    S.new(1, 2).freeze, # frozen Struct
+    S.new(1, 2, 3, 4).freeze, # frozen Struct
+    (1..2), # Range on Struct
+    (1..),  # Range on Struct
+    (..1),  # Range on Struct
+    C, # class
+    M, # module
+    Ractor.current, # Ractor
+  ]
+
+  unshareable_objects = [
+    'mutable str'.dup,
+    [:array],
+    {hash: true},
+    S.new(1, 2),
+    S.new(1, 2, 3, 4),
+    S.new("a", 2).freeze, # frozen, but refers to an unshareable object
+  ]
+
+  results = []
+
+  shareable_objects.map{|o|
+    echo_ractor << o
+    o2 = echo_ractor.take
+    results << "#{o} is copied" unless o.object_id == o2.object_id
+  }
+
+  unshareable_objects.map{|o|
+    echo_ractor << o
+    o2 = echo_ractor.take
+    results << "#{o.inspect} is not copied" if o.object_id == o2.object_id
+  }
+
+  if results.empty?
+    :ok
+  else
+    results.inspect
+  end
+}
+
+# frozen Objects are shareable
+assert_equal [false, true, false].inspect, %q{
+  class C
+    def initialize freeze
+      @a = 1
+      @b = :sym
+      @c = 'frozen_str'
+      @c.freeze if freeze
+      @d = true
+    end
+  end
+
+  def check obj1
+    obj2 = Ractor.new obj1 do |obj|
+      obj
+    end.take
+
+    obj1.object_id == obj2.object_id
+  end
+
+  results = []
+  results << check(C.new(true))         # false
+  results << check(C.new(true).freeze)  # true
+  results << check(C.new(false).freeze) # false
+}
+
+# move example2: String
+# touching moved object causes an error
+assert_equal 'hello world', %q{
+  # move
+  r = Ractor.new do
+    obj = Ractor.receive
+    obj << ' world'
+  end
+
+  str = 'hello'
+  r.send str, move: true
+  modified = r.take
+
+  begin
+    str << ' exception' # raise Ractor::MovedError
+  rescue Ractor::MovedError
+    modified #=> 'hello world'
+  else
+    raise 'unreachable'
+  end
+}
+
+# move example2: Array
+assert_equal '[0, 1]', %q{
+  r = Ractor.new do
+    ary = Ractor.receive
+    ary << 1
+  end
+
+  a1 = [0]
+  r.send a1, move: true
+  a2 = r.take
+  begin
+    a1 << 2 # raise Ractor::MovedError
+  rescue Ractor::MovedError
+    a2.inspect
+  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{
+  r = Ractor.new do
+    obj = Thread.new{}
+    Ractor.yield obj
+  rescue => e
+    e.message
+  end
+  r.take
+}
+
+# Access to global-variables are prohibited
+assert_equal 'can not access global variables $gv from non-main Ractors', %q{
+  $gv = 1
+  r = Ractor.new do
+    $gv
+  end
+
+  begin
+    r.take
+  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{
+  r = Ractor.new do
+    $gv = 1
+  end
+
+  begin
+    r.take
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
+# $stdin,out,err is Ractor local, but shared fds
+assert_equal 'ok', %q{
+  r = Ractor.new do
+    [$stdin, $stdout, $stderr].map{|io|
+      [io.object_id, io.fileno]
+    }
+  end
+
+  [$stdin, $stdout, $stderr].zip(r.take){|io, (oid, fno)|
+    raise "should not be different object" if io.object_id == oid
+    raise "fd should be same" unless io.fileno == fno
+  }
+  'ok'
+}
+
+# $stdin,out,err belong to Ractor
+assert_equal 'ok', %q{
+  r = Ractor.new do
+    $stdin.itself
+    $stdout.itself
+    $stderr.itself
+    'ok'
+  end
+
+  r.take
+}
+
+# $DEBUG, $VERBOSE are Ractor local
+assert_equal 'true', %q{
+  $DEBUG = true
+  $VERBOSE = true
+
+  def ractor_local_globals
+    /a(b)(c)d/ =~ 'abcd' # for $~
+    `echo foo` unless  /solaris/ =~ RUBY_PLATFORM
+
+    {
+     # ractor-local (derived from created ractor): debug
+     '$DEBUG' => $DEBUG,
+     '$-d' => $-d,
+
+     # ractor-local (derived from created ractor): verbose
+     '$VERBOSE' => $VERBOSE,
+     '$-w' => $-w,
+     '$-W' => $-W,
+     '$-v' => $-v,
+
+     # process-local (readonly): other commandline parameters
+     '$-p' => $-p,
+     '$-l' => $-l,
+     '$-a' => $-a,
+
+     # process-local (readonly): getpid
+     '$$'  => $$,
+
+     # thread local: process result
+     '$?'  => $?,
+
+     # scope local: match
+     '$~'  => $~.inspect,
+     '$&'  => $&,
+     '$`'  => $`,
+     '$\''  => $',
+     '$+'  => $+,
+     '$1'  => $1,
+
+     # scope local: last line
+     '$_' => $_,
+
+     # scope local: last backtrace
+     '$@' => $@,
+     '$!' => $!,
+
+     # ractor local: stdin, out, err
+     '$stdin'  => $stdin.inspect,
+     '$stdout' => $stdout.inspect,
+     '$stderr' => $stderr.inspect,
+    }
+  end
+
+  h = Ractor.new do
+    ractor_local_globals
+  end.take
+  ractor_local_globals == h #=> true
+}
+
+# selfs are different objects
+assert_equal 'false', %q{
+  r = Ractor.new do
+    self.object_id
+  end
+  r.take == self.object_id #=> false
+}
+
+# self is a Ractor instance
+assert_equal 'true', %q{
+  r = Ractor.new do
+    self.object_id
+  end
+  r.object_id == r.take #=> true
+}
+
+# given block Proc will be isolated, so can not access outer variables.
+assert_equal 'ArgumentError', %q{
+  begin
+    a = true
+    r = Ractor.new do
+      a
+    end
+  rescue => e
+    e.class
+  end
+}
+
+# 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{
+  class C
+    @iv = 'str'
+  end
+
+  r = Ractor.new do
+    class C
+      p @iv
+    end
+  end
+
+
+  begin
+    r.take
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
+# 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{
+  shared = Ractor.new{}
+  shared.instance_variable_set(:@iv, 'str')
+
+  r = Ractor.new shared do |shared|
+    p shared.instance_variable_get(:@iv)
+  end
+
+  begin
+    r.take
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
+# ivar in shareable-objects are not allowed to access from non-main Ractor, by @iv (get)
+assert_equal 'can not access instance variables of shareable objects from non-main Ractors', %q{
+  class Ractor
+    def setup
+      @foo = ''
+    end
+
+    def foo
+      @foo
+    end
+  end
+
+  shared = Ractor.new{}
+  shared.setup
+
+  r = Ractor.new shared do |shared|
+    p shared.foo
+  end
+
+  begin
+    r.take
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
+# ivar in shareable-objects are not allowed to access from non-main Ractor, by @iv (set)
+assert_equal 'can not access instance variables of shareable objects from non-main Ractors', %q{
+  class Ractor
+    def setup
+      @foo = ''
+    end
+  end
+
+  shared = Ractor.new{}
+
+  r = Ractor.new shared do |shared|
+    p shared.setup
+  end
+
+  begin
+    r.take
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
+# But a shareable object is frozen, it is allowed to access ivars from non-main Ractor
+assert_equal '11', %q{
+  [Object.new, [], ].map{|obj|
+    obj.instance_variable_set('@a', 1)
+    Ractor.make_shareable obj = obj.freeze
+
+    Ractor.new obj do |obj|
+      obj.instance_variable_get('@a')
+    end.take.to_s
+  }.join
+}
+
+# and instance variables of classes/modules are accessible if they refer shareable objects
+assert_equal '333', %q{
+  class C
+    @int = 1
+    @str = '-1000'.dup
+    @fstr = '100'.freeze
+
+    def self.int = @int
+    def self.str = @str
+    def self.fstr = @fstr
+  end
+
+  module M
+    @int = 2
+    @str = '-2000'.dup
+    @fstr = '200'.freeze
+
+    def self.int = @int
+    def self.str = @str
+    def self.fstr = @fstr
+  end
+
+  a = Ractor.new{ C.int }.take
+  b = Ractor.new do
+    C.str.to_i
+  rescue Ractor::IsolationError
+    10
+  end.take
+  c = Ractor.new do
+    C.fstr.to_i
+  end.take
+
+  d = Ractor.new{ M.int }.take
+  e = Ractor.new do
+    M.str.to_i
+  rescue Ractor::IsolationError
+    20
+  end.take
+  f = Ractor.new do
+    M.fstr.to_i
+  end.take
+
+
+  # 1 + 10 + 100 + 2 + 20 + 200
+  a + b + c + d + e + f
+}
+
+# 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{
+  class C
+    @@cv = 'str'
+  end
+
+  r = Ractor.new do
+    class C
+      p @@cv
+    end
+  end
+
+  begin
+    r.take
+  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{
+  class C
+    @@cv = 'str'
+    def self.cv
+      @@cv
+    end
+  end
+
+  C.cv # cache
+
+  r = Ractor.new do
+    C.cv
+  end
+
+  begin
+    r.take
+  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{
+  class C
+    CONST = 'str'
+  end
+  r = Ractor.new do
+    C::CONST
+  end
+  begin
+    r.take
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
+# 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{
+  STR = "hello"
+  def str; STR; end
+  s = str() # fill const cache
+  begin
+    Ractor.new{ str() }.take
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
+# 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{
+  class C
+  end
+  r = Ractor.new do
+    C::CONST = 'str'
+  end
+  begin
+    r.take
+  rescue Ractor::RemoteError => e
+    e.cause.message
+  end
+}
+
+# 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
+  rescue => e
+    e.cause.message
+  end
+}
+
+# Immutable Array and Hash are shareable, so it can be shared with constants
+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.count
+assert_equal '[1, 4, 3, 2, 1]', %q{
+  counts = []
+  counts << Ractor.count
+  ractors = (1..3).map { Ractor.new { Ractor.receive } }
+  counts << Ractor.count
+
+  ractors[0].send('End 0').take
+  sleep 0.1 until ractors[0].inspect =~ /terminated/
+  counts << Ractor.count
+
+  ractors[1].send('End 1').take
+  sleep 0.1 until ractors[1].inspect =~ /terminated/
+  counts << Ractor.count
+
+  ractors[2].send('End 2').take
+  sleep 0.1 until ractors[2].inspect =~ /terminated/
+  counts << Ractor.count
+
+  counts.inspect
+}
+
+# ObjectSpace.each_object can not handle unshareable objects with Ractors
+assert_equal '0', %q{
+  Ractor.new{
+    n = 0
+    ObjectSpace.each_object{|o| n += 1 unless Ractor.shareable?(o)}
+    n
+  }.take
+}
+
+# ObjectSpace._id2ref can not handle unshareable objects with Ractors
+assert_equal 'ok', %q{
+  s = 'hello'
+
+  Ractor.new s.object_id do |id ;s|
+    begin
+      s = ObjectSpace._id2ref(id)
+    rescue => e
+      :ok
+    end
+  end.take
+}
+
+# Ractor.make_shareable(obj)
+assert_equal 'true', %q{
+  class C
+    def initialize
+      @a = 'foo'
+      @b = 'bar'
+    end
+
+    def freeze
+      @c = [:freeze_called]
+      super
+    end
+
+    attr_reader :a, :b, :c
+  end
+  S = Struct.new(:s1, :s2)
+  str = "hello"
+  str.instance_variable_set("@iv", "hello")
+  /a/ =~ 'a'
+  m = $~
+  class N < Numeric
+    def /(other)
+      1
+    end
+  end
+  ary = []; ary << ary
+
+  a = [[1, ['2', '3']],
+       {Object.new => "hello"},
+       C.new,
+       S.new("x", "y"),
+       ("a".."b"),
+       str,
+       ary,             # cycle
+       /regexp/,
+       /#{'r'.upcase}/,
+       m,
+       Complex(N.new,0),
+       Rational(N.new,0),
+       true,
+       false,
+       nil,
+       1, 1.2, 1+3r, 1+4i, # Numeric
+  ]
+  Ractor.make_shareable(a)
+
+  # check all frozen
+  a.each{|o|
+    raise o.inspect unless o.frozen?
+
+    case o
+    when C
+      raise o.a.inspect unless o.a.frozen?
+      raise o.b.inspect unless o.b.frozen?
+      raise o.c.inspect unless o.c.frozen? && o.c == [:freeze_called]
+    when Rational
+      raise o.numerator.inspect unless o.numerator.frozen?
+    when Complex
+      raise o.real.inspect unless o.real.frozen?
+    when Array
+      if o[0] == 1
+        raise o[1][1].inspect unless o[1][1].frozen?
+      end
+    when Hash
+      o.each{|k, v|
+        raise k.inspect unless k.frozen?
+        raise v.inspect unless v.frozen?
+      }
+    end
+  }
+
+  Ractor.shareable?(a)
+}
+
+# Ractor.make_shareable(obj) doesn't freeze shareable objects
+assert_equal 'true', %q{
+  r = Ractor.new{}
+  Ractor.make_shareable(a = [r])
+  [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"}]
+
+  pr = Ractor.current.instance_eval do
+    Proc.new do
+      a
+    end
+  end
+
+  Ractor.make_shareable(a) # referred value should be shareable
+  Ractor.make_shareable(pr)
+  Ractor.shareable?(pr)
+}
+
+# Ractor.shareable?(recursive_objects)
+assert_equal '[false, false]', %q{
+  y = []
+  x = [y, {}].freeze
+  y << x
+  y.freeze
+  [Ractor.shareable?(x), Ractor.shareable?(y)]
+}
+
+# Ractor.make_shareable(recursive_objects)
+assert_equal '[:ok, false, false]', %q{
+  o = Object.new
+  def o.freeze; raise; end
+  y = []
+  x = [y, o].freeze
+  y << x
+  y.freeze
+  [(Ractor.make_shareable(x) rescue :ok), Ractor.shareable?(x), Ractor.shareable?(y)]
+}
+
+# Ractor.make_shareable with Class/Module
+assert_equal '[C, M]', %q{
+  class C; end
+  module M; end
+
+  Ractor.make_shareable(ary = [C, M])
+}
+
+# define_method() can invoke different Ractor's proc if the proc is shareable.
+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
+  end
+
+  begin
+    Ractor.make_shareable(pr)
+  rescue => e
+    e.message
+  end
+}
+
+# Ractor.make_shareable(obj, copy: true) makes copied shareable object.
+assert_equal '[false, false, true, true]', %q{
+  r = []
+  o1 = [1, 2, ["3"]]
+
+  o2 = Ractor.make_shareable(o1, copy: true)
+  r << Ractor.shareable?(o1) # false
+  r << (o1.object_id == o2.object_id) # false
+
+  o3 = Ractor.make_shareable(o1)
+  r << Ractor.shareable?(o1) # true
+  r << (o1.object_id == o3.object_id) # false
+  r
+}
+
+# TracePoint with normal Proc should be Ractor local
+assert_equal '[4, 8]', %q{
+  rs = []
+  TracePoint.new(:line){|tp| rs << tp.lineno if tp.path == __FILE__}.enable do
+    Ractor.new{ # line 4
+      a = 1
+      b = 2
+    }.take
+    c = 3       # line 8
+  end
+  rs
+}
+
+# Ractor deep copies frozen objects (ary)
+assert_equal '[true, false]', %q{
+  Ractor.new([[]].freeze) { |ary|
+    [ary.frozen?, ary.first.frozen? ]
+  }.take
+}
+
+# Ractor deep copies frozen objects (str)
+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
+}
+
+# Can not trap with not isolated Proc on non-main ractor
+assert_equal '[:ok, :ok]', %q{
+  a = []
+  Ractor.new{
+    trap(:INT){p :ok}
+  }.take
+  a << :ok
+
+  begin
+    Ractor.new{
+      s = 'str'
+      trap(:INT){p s}
+    }.take
+  rescue => Ractor::RemoteError
+    a << :ok
+  end
+}
+
+# Ractor-local storage
+assert_equal '[nil, "b", "a"]', %q{
+  ans = []
+  Ractor.current[:key] = 'a'
+  r = Ractor.new{
+    Ractor.yield self[:key]
+    self[:key] = 'b'
+    self[:key]
+  }
+  ans << r.take
+  ans << r.take
+  ans << Ractor.current[:key]
+}
+
+###
+### Synchronization tests
+###
+
+N = 100_000
+
+# fstring pool
+assert_equal "#{N}#{N}", %Q{
+  N = #{N}
+  2.times.map{
+    Ractor.new{
+      N.times{|i| -(i.to_s)}
+    }
+  }.map{|r| r.take}.join
+}
+
+# enc_table
+assert_equal "100", %Q{
+  Ractor.new do
+    loop do
+      Encoding.find("test-enc-#{rand(5_000)}").inspect
+    rescue ArgumentError => e
+    end
+  end
+
+  src = Encoding.find("UTF-8")
+  100.times{|i|
+    src.replicate("test-enc-\#{i}")
+  }
+}
+
+# Generic ivtbl
+n = N/2
+assert_equal "#{n}#{n}", %Q{
+  2.times.map{
+    Ractor.new do
+      #{n}.times do
+        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
+}
+
+# NameError
+assert_equal "ok", %q{
+  begin
+    bar
+  rescue => err
+  end
+  begin
+    Ractor.new{} << err
+  rescue TypeError
+    'ok'
+  end
+}
+
+assert_equal "ok", %q{
+  GC.disable
+  Ractor.new {}
+  raise "not ok" unless GC.disable
+
+  foo = []
+  10.times { foo << 1 }
+
+  GC.start
+
+  'ok'
+}
+
+# Can yield back values while GC is sweeping [Bug #18117]
+assert_equal "ok", %q{
+  workers = (0...8).map do
+    Ractor.new do
+      loop do
+        10_000.times.map { Object.new }
+        Ractor.yield Time.now
+      end
+    end
+  end
+
+  1_000.times { idle_worker, tmp_reporter = Ractor.select(*workers) }
+  "ok"
+}
+
+assert_equal "ok", %q{
+  def foo(*); ->{ super }; end
+  begin
+    Ractor.make_shareable(foo)
+  rescue Ractor::IsolationError
+    "ok"
+  end
+}
+
+assert_equal "ok", %q{
+  def foo(**); ->{ super }; end
+  begin
+    Ractor.make_shareable(foo)
+  rescue Ractor::IsolationError
+    "ok"
+  end
+}
+
+assert_equal "ok", %q{
+  def foo(...); ->{ super }; end
+  begin
+    Ractor.make_shareable(foo)
+  rescue Ractor::IsolationError
+    "ok"
+  end
+}
+
+assert_equal "ok", %q{
+  def foo((x), (y)); ->{ super }; end
+  begin
+    Ractor.make_shareable(foo([], []))
+  rescue Ractor::IsolationError
+    "ok"
+  end
+}
+
+assert_equal "ok", %q{
+  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"
+}
+
+assert_match /\Atest_ractor\.rb:1:\s+warning:\s+Ractor is experimental/, %q{
+  Warning[:experimental] = $VERBOSE = true
+  STDERR.reopen(STDOUT)
+  eval("Ractor.new{}.take", nil, "test_ractor.rb", 1)
+}
+
+end # if !ENV['GITHUB_WORKFLOW']
diff --git a/bootstraptest/test_syntax.rb b/bootstraptest/test_syntax.rb
index fa27bf2aeb..948e2d7809 100644
--- a/bootstraptest/test_syntax.rb
+++ b/bootstraptest/test_syntax.rb
@@ -628,7 +628,7 @@ assert_equal '2', %q{
 }
 
 assert_match /invalid multibyte char/, %q{
-  STDERR.reopen(STDOUT)
+  $stderr = STDOUT
   eval("\"\xf0".force_encoding("utf-8"))
 }, '[ruby-dev:32429]'
 
diff --git a/bootstraptest/test_thread.rb b/bootstraptest/test_thread.rb
index 38a55ff229..5361828403 100644
--- a/bootstraptest/test_thread.rb
+++ b/bootstraptest/test_thread.rb
@@ -243,7 +243,7 @@ assert_equal 'true', %{
 }
 
 assert_equal 'ok', %{
-  open("zzz.rb", "w") do |f|
+  open("zzz_t1.rb", "w") do |f|
     f.puts <<-END
       begin
         Thread.new { fork { GC.start } }.join
@@ -254,7 +254,7 @@ assert_equal 'ok', %{
       end
     END
   end
-  require "./zzz.rb"
+  require "./zzz_t1.rb"
   $result
 }
 
@@ -408,7 +408,7 @@ assert_equal 'ok', %q{
 }
 
 assert_equal 'ok', %{
-  open("zzz.rb", "w") do |f|
+  open("zzz_t2.rb", "w") do |f|
     f.puts <<-'end;' # do
       begin
         m = Thread::Mutex.new
@@ -432,7 +432,7 @@ assert_equal 'ok', %{
       end
     end;
   end
-  require "./zzz.rb"
+  require "./zzz_t2.rb"
   $result
 }
 
diff --git a/bootstraptest/test_yjit.rb b/bootstraptest/test_yjit.rb
new file mode 100644
index 0000000000..5c655b8f25
--- /dev/null
+++ b/bootstraptest/test_yjit.rb
@@ -0,0 +1,3530 @@
+# 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)
+    victim = 5
+    five.define_singleton_method(:respond_to?) do |_, _|
+      victim = nil
+    end
+
+    # +1 makes YJIT track that victim is a number and
+    # defined? calls respond_to? from above indirectly
+    unless (victim + 1) && defined?(five.something)
+      # Would return wrong result if we still think `five` is a number
+      victim.nil?
+    end
+  end
+
+  local_setting_cmp(Object.new)
+  local_setting_cmp(Object.new)
+}
+
+assert_equal '18374962167983112447', %q{
+  # regression test for incorrectly discarding 32 bits of a pointer when it
+  # comes to default values.
+  def large_literal_default(n: 0xff00_fabcafe0_00ff)
+    n
+  end
+
+  def call_graph_root
+    large_literal_default
+  end
+
+  call_graph_root
+  call_graph_root
+}
+
+assert_normal_exit %q{
+  # regression test for a leak caught by an assert on --yjit-call-threshold=2
+  Foo = 1
+
+  eval("def foo = [#{(['Foo,']*256).join}]")
+
+  foo
+  foo
+
+  Object.send(:remove_const, :Foo)
+}
+
+assert_normal_exit %q{
+  # Test to ensure send on overriden 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")
+  end
+
+  [nil, true, false, 0xFABCAFE, 0.42, :cake].map do |instance|
+    instance.foo
+    instance.foo
+  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
+  end
+
+  class Sub
+    include M
+  end
+
+  foo_method = M.instance_method(:foo)
+
+  dbg = ->(message) do
+    return # comment this out to get printouts
+
+    $stderr.puts RubyVM::YJIT.disasm(foo_method)
+    $stderr.puts message
+  end
+
+  2.times { 42.only_ints }
+
+  dbg["There should be two versions of getinlineache"]
+
+  module M
+    remove_const(:Foo)
+  end
+
+  dbg["There should be no getinlinecaches"]
+
+  2.times do
+    42.only_ints
+  rescue NameError => err
+    _ = "caught name error #{err}"
+  end
+
+  dbg["There should be one version of getinlineache"]
+
+  2.times do
+    Sub.new.pin_self_type_then_foo
+  rescue NameError
+    _ = 'second specialization'
+  end
+
+  dbg["There should be two versions of getinlineache"]
+
+  module M
+    Foo = 1
+  end
+
+  dbg["There should still be two versions of getinlineache"]
+
+  42.only_ints
+
+  dbg["There should be no getinlinecaches"]
+
+  # 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
+  end
+}
+
+# Check that frozen objects are respected
+assert_equal 'great', %q{
+  class Foo
+    attr_accessor :bar
+    def initialize
+      @bar = 1
+      freeze
+    end
+  end
+
+  foo = Foo.new
+
+  5.times do
+    begin
+      foo.bar = 2
+    rescue FrozenError
+    end
+  end
+
+  foo.bar == 1 ? "great" : "NG"
+}
+
+# Check that global variable set works
+assert_equal 'string', %q{
+  def foo
+    $foo = "string"
+  end
+
+  foo
+}
+
+# Check that exceptions work when setting global variables
+assert_equal 'rescued', %q{
+  def set_var
+    $var = 100
+  rescue
+    :rescued
+  end
+
+  set_var
+  trace_var(:$var) { raise }
+  set_var
+}
+
+# Check that global variables work
+assert_equal 'string', %q{
+  $foo = "string"
+
+  def foo
+    $foo
+  end
+
+  foo
+}
+
+# Check that exceptions work when getting global variable
+assert_equal 'rescued', %q{
+  Warning[:deprecated] = true
+
+  module Warning
+    def warn(message)
+      raise
+    end
+  end
+
+  def get_var
+    $=
+  rescue
+    :rescued
+  end
+
+  $VERBOSE = true
+  get_var
+  get_var
+}
+
+# Check that global tracepoints work
+assert_equal 'true', %q{
+  def foo
+    1
+  end
+
+  foo
+  foo
+  foo
+
+  called = false
+
+  tp = TracePoint.new(:return) { |event|
+    if event.method_id == :foo
+      called = true
+    end
+  }
+  tp.enable
+  foo
+  tp.disable
+  called
+}
+
+# Check that local tracepoints work
+assert_equal 'true', %q{
+  def foo
+    1
+  end
+
+  foo
+  foo
+  foo
+
+  called = false
+
+  tp = TracePoint.new(:return) { |_| called = true }
+  tp.enable(target: method(:foo))
+  foo
+  tp.disable
+  called
+}
+
+# Make sure that optional param methods return the correct value
+assert_equal '1', %q{
+  def m(ary = [])
+    yield(ary)
+  end
+
+  # Warm the JIT with a 0 param call
+  2.times { m { } }
+  m(1) { |v| v }
+}
+
+# Test for topn
+assert_equal 'array', %q{
+  def threequals(a)
+    case a
+    when Array
+      "array"
+    when Hash
+      "hash"
+    else
+      "unknown"
+    end
+  end
+
+  threequals([])
+  threequals([])
+  threequals([])
+}
+
+# Test for opt_mod
+assert_equal '2', %q{
+  def mod(a, b)
+    a % b
+  end
+
+  mod(7, 5)
+  mod(7, 5)
+}
+
+# Test for opt_mult
+assert_equal '12', %q{
+  def mult(a, b)
+    a * b
+  end
+
+  mult(6, 2)
+  mult(6, 2)
+}
+
+# Test for opt_div
+assert_equal '3', %q{
+  def div(a, b)
+    a / b
+  end
+
+  div(6, 2)
+  div(6, 2)
+}
+
+# BOP redefined methods work when JIT compiled
+assert_equal 'false', %q{
+  def less_than x
+    x < 10
+  end
+
+  class Integer
+    def < x
+      false
+    end
+  end
+
+  less_than 2
+  less_than 2
+  less_than 2
+}
+
+# BOP redefinition works on Integer#<
+assert_equal 'false', %q{
+  def less_than x
+    x < 10
+  end
+
+  less_than 2
+  less_than 2
+
+  class Integer
+    def < x
+      false
+    end
+  end
+
+  less_than 2
+}
+
+# Putobject, less-than operator, fixnums
+assert_equal '2', %q{
+    def check_index(index)
+        if 0x40000000 < index
+            raise "wat? #{index}"
+        end
+        index
+    end
+    check_index 2
+    check_index 2
+}
+
+# foo leaves a temp on the stack before the call
+assert_equal '6', %q{
+    def bar
+        return 5
+    end
+
+    def foo
+        return 1 + bar
+    end
+
+    foo()
+    retval = foo()
+}
+
+# Method with one arguments
+# foo leaves a temp on the stack before the call
+assert_equal '7', %q{
+    def bar(a)
+        return a + 1
+    end
+
+    def foo
+        return 1 + bar(5)
+    end
+
+    foo()
+    retval = foo()
+}
+
+# Method with two arguments
+# foo leaves a temp on the stack before the call
+assert_equal '0', %q{
+    def bar(a, b)
+        return a - b
+    end
+
+    def foo
+        return 1 + bar(1, 2)
+    end
+
+    foo()
+    retval = foo()
+}
+
+# Passing argument types to callees
+assert_equal '8.5', %q{
+    def foo(x, y)
+        x + y
+    end
+
+    def bar
+        foo(7, 1.5)
+    end
+
+    bar
+    bar
+}
+
+# Recursive Ruby-to-Ruby calls
+assert_equal '21', %q{
+    def fib(n)
+        if n < 2
+            return n
+        end
+
+        return fib(n-1) + fib(n-2)
+    end
+
+    r = fib(8)
+}
+
+# Ruby-to-Ruby call and C call
+assert_normal_exit %q{
+  def bar
+    puts('hi!')
+  end
+
+  def foo
+    bar
+  end
+
+  foo()
+  foo()
+}
+
+# Method aliasing
+assert_equal '42', %q{
+  class Foo
+    def method_a
+      42
+    end
+
+    alias method_b method_a
+
+    def method_a
+        :somethingelse
+    end
+  end
+
+  @obj = Foo.new
+
+  def test
+    @obj.method_b
+  end
+
+  test
+  test
+}
+
+# Method aliasing with method from parent class
+assert_equal '777', %q{
+  class A
+    def method_a
+      777
+    end
+  end
+
+  class B < A
+    alias method_b method_a
+  end
+
+  @obj = B.new
+
+  def test
+    @obj.method_b
+  end
+
+  test
+  test
+}
+
+# The hash method is a C function and uses the self argument
+assert_equal 'true', %q{
+    def lehashself
+        hash
+    end
+
+    a = lehashself
+    b = lehashself
+    a == b
+}
+
+# Method redefinition (code invalidation) test
+assert_equal '1', %q{
+    def ret1
+        return 1
+    end
+
+    klass = Class.new do
+        def alias_then_hash(klass, method_to_redefine)
+            # Redefine the method to be ret1
+            klass.alias_method(method_to_redefine, :ret1)
+            hash
+        end
+    end
+
+    instance = klass.new
+
+    i = 0
+    while i < 12
+        if i < 11
+            # Redefine the bar method
+            instance.alias_then_hash(klass, :bar)
+        else
+            # Redefine the hash method to be ret1
+            retval = instance.alias_then_hash(klass, :hash)
+        end
+        i += 1
+    end
+
+    retval
+}
+
+# Code invalidation and opt_getinlinecache
+assert_normal_exit %q{
+  class Foo; end
+
+  # Uses the class constant Foo
+  def use_constant(arg)
+    [Foo.new, arg]
+  end
+
+  def propagate_type
+    i = Array.new
+    i.itself # make it remember that i is on-heap
+    use_constant(i)
+  end
+
+  propagate_type
+  propagate_type
+  use_constant(Foo.new)
+  class Jo; end # bump global constant state
+  use_constant(3)
+}
+
+# Method redefinition (code invalidation) and GC
+assert_equal '7', %q{
+    def bar()
+        return 5
+    end
+
+    def foo()
+        bar()
+    end
+
+    foo()
+    foo()
+
+    def bar()
+        return 7
+    end
+
+    4.times { GC.start }
+
+    foo()
+    foo()
+}
+
+# Method redefinition with two block versions
+assert_equal '7', %q{
+    def bar()
+        return 5
+    end
+
+    def foo(n)
+        return ((n < 5)? 5:false), bar()
+    end
+
+    foo(4)
+    foo(4)
+    foo(10)
+    foo(10)
+
+    def bar()
+        return 7
+    end
+
+    4.times { GC.start }
+
+    foo(4)
+    foo(4)[1]
+}
+
+# Method redefinition while the method is on the stack
+assert_equal '[777, 1]', %q{
+    def foo
+        redef()
+        777
+    end
+
+    def redef
+        # Redefine the global foo
+        eval("def foo; 1; end", TOPLEVEL_BINDING)
+
+        # Collect dead code
+        GC.stress = true
+        GC.start
+
+        # But we will return to the original foo,
+        # which remains alive because it's on the stack
+    end
+
+    # Must produce [777, 1]
+    [foo, foo]
+}
+
+# Test for GC safety. Don't invalidate dead iseqs.
+assert_normal_exit %q{
+  Class.new do
+    def foo
+      itself
+    end
+
+    new.foo
+    new.foo
+    new.foo
+    new.foo
+  end
+
+  4.times { GC.start }
+  def itself
+    self
+  end
+}
+
+# test setinstancevariable on extended objects
+assert_equal '1', %q{
+  class Extended
+    attr_reader :one
+
+    def write_many
+      @a = 1
+      @b = 2
+      @c = 3
+      @d = 4
+      @one = 1
+    end
+  end
+
+  foo = Extended.new
+  foo.write_many
+  foo.write_many
+  foo.write_many
+}
+
+# test setinstancevariable on embedded objects
+assert_equal '1', %q{
+  class Embedded
+    attr_reader :one
+
+    def write_one
+      @one = 1
+    end
+  end
+
+  foo = Embedded.new
+  foo.write_one
+  foo.write_one
+  foo.write_one
+}
+
+# test setinstancevariable after extension
+assert_equal '[10, 11, 12, 13, 1]', %q{
+  class WillExtend
+    attr_reader :one
+
+    def make_extended
+      @foo1 = 10
+      @foo2 = 11
+      @foo3 = 12
+      @foo4 = 13
+    end
+
+    def write_one
+      @one = 1
+    end
+
+    def read_all
+      [@foo1, @foo2, @foo3, @foo4, @one]
+    end
+  end
+
+  foo = WillExtend.new
+  foo.write_one
+  foo.write_one
+  foo.make_extended
+  foo.write_one
+  foo.read_all
+}
+
+# test setinstancevariable on frozen object
+assert_equal 'object was not modified', %q{
+  class WillFreeze
+    def write
+      @ivar = 1
+    end
+  end
+
+  wf = WillFreeze.new
+  wf.write
+  wf.write
+  wf.freeze
+
+  begin
+    wf.write
+  rescue FrozenError
+    "object was not modified"
+  end
+}
+
+# Test getinstancevariable and inline caches
+assert_equal '6', %q{
+  class Foo
+    def initialize
+      @x1 = 1
+      @x2 = 1
+      @x2 = 1
+      @x3 = 1
+      @x4 = 3
+    end
+
+    def bar
+      x = 1
+      @x4 + @x4
+    end
+  end
+
+  f = Foo.new
+  f.bar
+  f.bar
+}
+
+# Test that getinstancevariable codegen checks for extended table size
+assert_equal "nil\n", %q{
+  class A
+    def read
+      @ins1000
+    end
+  end
+
+  ins = A.new
+  other = A.new
+  10.times { other.instance_variable_set(:"@otr#{_1}", 'value') }
+  1001.times { ins.instance_variable_set(:"@ins#{_1}", 'value') }
+
+  ins.read
+  ins.read
+  ins.read
+
+  p other.read
+}
+
+# Test that opt_aref checks the class of the receiver
+assert_equal 'special', %q{
+  def foo(array)
+    array[30]
+  end
+
+  foo([])
+  foo([])
+
+  special = []
+  def special.[](idx)
+    'special'
+  end
+
+  foo(special)
+}
+
+# Test that object references in generated code get marked and moved
+assert_equal "good", %q{
+  def bar
+    "good"
+  end
+
+  def foo
+    bar
+  end
+
+  foo
+  foo
+
+  begin
+    GC.verify_compaction_references(expand_heap: true, toward: :empty)
+  rescue NotImplementedError
+    # in case compaction isn't supported
+  end
+
+  foo
+}
+
+# Test polymorphic getinstancevariable. T_OBJECT -> T_STRING
+assert_equal 'ok', %q{
+  @hello = @h1 = @h2 = @h3 = @h4 = 'ok'
+  str = ""
+  str.instance_variable_set(:@hello, 'ok')
+
+  public def get
+    @hello
+  end
+
+  get
+  get
+  str.get
+  str.get
+}
+
+# Test polymorphic getinstancevariable, two different classes
+assert_equal 'ok', %q{
+  class Embedded
+    def initialize
+      @ivar = 0
+    end
+
+    def get
+      @ivar
+    end
+  end
+
+  class Extended < Embedded
+    def initialize
+      @v1 = @v2 = @v3 = @v4 = @ivar = 'ok'
+    end
+  end
+
+  embed = Embedded.new
+  extend = Extended.new
+
+  embed.get
+  embed.get
+  extend.get
+  extend.get
+}
+
+# Test megamorphic getinstancevariable
+assert_equal 'ok', %q{
+  parent = Class.new do
+    def initialize
+      @hello = @h1 = @h2 = @h3 = @h4 = 'ok'
+    end
+
+    def get
+      @hello
+    end
+  end
+
+  subclasses = 300.times.map { Class.new(parent) }
+  subclasses.each { _1.new.get }
+  parent.new.get
+}
+
+# Test polymorphic opt_aref. array -> hash
+assert_equal '[42, :key]', %q{
+  def index(obj, idx)
+    obj[idx]
+  end
+
+  index([], 0) # get over compilation threshold
+
+  [
+    index([42], 0),
+    index({0=>:key}, 0),
+  ]
+}
+
+# Test polymorphic opt_aref. hash -> array -> custom class
+assert_equal '[nil, nil, :custom]', %q{
+  def index(obj, idx)
+    obj[idx]
+  end
+
+  custom = Object.new
+  def custom.[](_idx)
+    :custom
+  end
+
+  index({}, 0) # get over compilation threshold
+
+  [
+    index({}, 0),
+    index([], 0),
+    index(custom, 0)
+  ]
+}
+
+# Test polymorphic opt_aref. array -> custom class
+assert_equal '[42, :custom]', %q{
+  def index(obj, idx)
+    obj[idx]
+  end
+
+  custom = Object.new
+  def custom.[](_idx)
+    :custom
+  end
+
+  index([], 0) # get over compilation threshold
+
+  [
+    index([42], 0),
+    index(custom, 0)
+  ]
+}
+
+# Test custom hash method with opt_aref
+assert_equal '[nil, :ok]', %q{
+  def index(obj, idx)
+    obj[idx]
+  end
+
+  custom = Object.new
+  def custom.hash
+    42
+  end
+
+  h = {custom => :ok}
+
+  [
+    index(h, 0),
+    index(h, custom)
+  ]
+}
+
+# Test default value block for Hash with opt_aref
+assert_equal '[42, :default]', %q{
+  def index(obj, idx)
+    obj[idx]
+  end
+
+  h = Hash.new { :default }
+  h[0] = 42
+
+  [
+    index(h, 0),
+    index(h, 1)
+  ]
+}
+
+# A regression test for making sure cfp->sp is proper when
+# hitting stubs. See :stub-sp-flush:
+assert_equal 'ok', %q{
+  class D
+    def foo
+      Object.new
+    end
+  end
+
+  GC.stress = true
+  10.times do
+    D.new.foo
+    #    ^
+    #  This hits a stub with sp_offset > 0
+  end
+
+  :ok
+}
+
+# Test polymorphic callsite, cfunc -> iseq
+assert_equal '[Cfunc, Iseq]', %q{
+  public def call_itself
+    itself # the polymorphic callsite
+  end
+
+  class Cfunc; end
+
+  class Iseq
+    def itself
+      self
+    end
+  end
+
+  call_itself # cross threshold
+
+  [Cfunc.call_itself, Iseq.call_itself]
+}
+
+# Test polymorphic callsite, iseq -> cfunc
+assert_equal '[Iseq, Cfunc]', %q{
+  public def call_itself
+    itself # the polymorphic callsite
+  end
+
+  class Cfunc; end
+
+  class Iseq
+    def itself
+      self
+    end
+  end
+
+  call_itself # cross threshold
+
+  [Iseq.call_itself, Cfunc.call_itself]
+}
+
+# attr_reader method
+assert_equal '[100, 299]', %q{
+  class A
+    attr_reader :foo
+
+    def initialize
+      @foo = 100
+    end
+
+    # Make it extended
+    def fill!
+      @bar = @jojo = @as = @sdfsdf = @foo = 299
+    end
+  end
+
+  def bar(ins)
+    ins.foo
+  end
+
+  ins = A.new
+  oth = A.new
+  oth.fill!
+
+  bar(ins)
+  bar(oth)
+
+  [bar(ins), bar(oth)]
+}
+
+# get ivar on object, then on hash
+assert_equal '[42, 100]', %q{
+  class Hash
+    attr_accessor :foo
+  end
+
+  class A
+    attr_reader :foo
+
+    def initialize
+      @foo = 42
+    end
+  end
+
+  def use(val)
+    val.foo
+  end
+
+
+  h = {}
+  h.foo = 100
+  obj = A.new
+
+  use(obj)
+  [use(obj), use(h)]
+}
+
+# get ivar on String
+assert_equal '[nil, nil, 42, 42]', %q{
+  # @foo to exercise the getinstancevariable instruction
+  public def get_foo
+    @foo
+  end
+
+  get_foo
+  get_foo # compile it for the top level object
+
+  class String
+    attr_reader :foo
+  end
+
+  def run
+    str = String.new
+
+    getter = str.foo
+    insn = str.get_foo
+
+    str.instance_variable_set(:@foo, 42)
+
+    [getter, insn, str.foo, str.get_foo]
+  end
+
+  run
+  run
+}
+
+# splatting an empty array on a getter
+assert_equal '42', %q{
+  @foo = 42
+  module Kernel
+    attr_reader :foo
+  end
+
+  def run
+    foo(*[])
+  end
+
+  run
+  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
+  public def get_foo
+    @foo
+  end
+
+  dyn_sym = ("a" + "b").to_sym
+  sym = :static
+
+  # compile get_foo
+  dyn_sym.get_foo
+  dyn_sym.get_foo
+
+  [dyn_sym.get_foo, sym.get_foo]
+}
+
+# attr_reader on Symbol
+assert_equal '[nil, nil]', %q{
+  class Symbol
+    attr_reader :foo
+  end
+
+  public def get_foo
+    foo
+  end
+
+  dyn_sym = ("a" + "b").to_sym
+  sym = :static
+
+  # compile get_foo
+  dyn_sym.get_foo
+  dyn_sym.get_foo
+
+  [dyn_sym.get_foo, sym.get_foo]
+}
+
+# passing too few arguments to method with optional parameters
+assert_equal 'raised', %q{
+  def opt(a, b = 0)
+  end
+
+  def use
+    opt
+  end
+
+  use rescue nil
+  begin
+    use
+    :ng
+  rescue ArgumentError
+    :raised
+  end
+}
+
+# passing too many arguments to method with optional parameters
+assert_equal 'raised', %q{
+  def opt(a, b = 0)
+  end
+
+  def use
+    opt(1, 2, 3, 4)
+  end
+
+  use rescue nil
+  begin
+    use
+    :ng
+  rescue ArgumentError
+    :raised
+  end
+}
+
+# test calling Ruby method with a block
+assert_equal '[1, 2, 42]', %q{
+  def thing(a, b)
+    [a, b, yield]
+  end
+
+  def use
+    thing(1,2) { 42 }
+  end
+
+  use
+  use
+}
+
+# test calling C method with a block
+assert_equal '[42, 42]', %q{
+  def use(array, initial)
+    array.reduce(initial) { |a, b| a + b }
+  end
+
+  use([], 0)
+  [use([2, 2], 38), use([14, 14, 14], 0)]
+}
+
+# test calling block param
+assert_equal '[1, 2, 42]', %q{
+  def foo(&block)
+    block.call
+  end
+
+  [foo {1}, foo {2}, foo {42}]
+}
+
+# test calling without block param
+assert_equal '[1, false, 2, false]', %q{
+  def bar
+    block_given? && yield
+  end
+
+  def foo(&block)
+    bar(&block)
+  end
+
+  [foo { 1 }, foo, foo { 2 }, foo]
+}
+
+# test calling block param failing
+assert_equal '42', %q{
+  def foo(&block)
+    block.call
+  end
+
+  foo {} # warmup
+
+  begin
+    foo
+  rescue NoMethodError => e
+    42 if nil == e.receiver
+  end
+}
+
+# test calling method taking block param
+assert_equal '[Proc, 1, 2, 3, Proc]', %q{
+  def three(a, b, c, &block)
+    [a, b, c, block.class]
+  end
+
+  def zero(&block)
+    block.class
+  end
+
+  def use_three
+    three(1, 2, 3) {}
+  end
+
+  def use_zero
+    zero {}
+  end
+
+  use_three
+  use_zero
+
+  [use_zero] + use_three
+}
+
+# test building empty array
+assert_equal '[]', %q{
+  def build_arr
+    []
+  end
+
+  build_arr
+  build_arr
+}
+
+# test building array of one element
+assert_equal '[5]', %q{
+  def build_arr(val)
+    [val]
+  end
+
+  build_arr(5)
+  build_arr(5)
+}
+
+# test building array of several element
+assert_equal '[5, 5, 5, 5, 5]', %q{
+  def build_arr(val)
+    [val, val, val, val, val]
+  end
+
+  build_arr(5)
+  build_arr(5)
+}
+
+# test building empty hash
+assert_equal '{}', %q{
+  def build_hash
+    {}
+  end
+
+  build_hash
+  build_hash
+}
+
+# test building hash with values
+assert_equal '{:foo=>:bar}', %q{
+  def build_hash(val)
+    { foo: val }
+  end
+
+  build_hash(:bar)
+  build_hash(:bar)
+}
+
+# test string interpolation with known types
+assert_equal 'foobar', %q{
+  def make_str
+    foo = -"foo"
+    bar = -"bar"
+    "#{foo}#{bar}"
+  end
+
+  make_str
+  make_str
+}
+
+# test string interpolation with unknown types
+assert_equal 'foobar', %q{
+  def make_str(foo, bar)
+    "#{foo}#{bar}"
+  end
+
+  make_str("foo", "bar")
+  make_str("foo", "bar")
+}
+
+# test string interpolation with known non-strings
+assert_equal 'foo123', %q{
+  def make_str
+    foo = -"foo"
+    bar = 123
+    "#{foo}#{bar}"
+  end
+
+  make_str
+  make_str
+}
+
+# test string interpolation with unknown non-strings
+assert_equal 'foo123', %q{
+  def make_str(foo, bar)
+    "#{foo}#{bar}"
+  end
+
+  make_str("foo", 123)
+  make_str("foo", 123)
+}
+
+# test that invalidation of String#to_s doesn't crash
+assert_equal 'meh', %q{
+  def inval_method
+    "".to_s
+  end
+
+  inval_method
+
+  class String
+    def to_s
+      "meh"
+    end
+  end
+
+  inval_method
+}
+
+# test that overriding to_s on a String subclass works consistently
+assert_equal 'meh', %q{
+  class MyString < String
+    def to_s
+      "meh"
+    end
+  end
+
+  def test_to_s(obj)
+    obj.to_s
+  end
+
+  OBJ = MyString.new
+
+  # Should return '' both times
+  test_to_s("")
+  test_to_s("")
+
+  # Can return '' if YJIT optimises String#to_s too aggressively
+  test_to_s(OBJ)
+  test_to_s(OBJ)
+}
+
+# test string interpolation with overridden to_s
+assert_equal 'foo', %q{
+  class String
+    def to_s
+      "bad"
+    end
+  end
+
+  def make_str(foo)
+    "#{foo}"
+  end
+
+  make_str("foo")
+  make_str("foo")
+}
+
+# Test that String unary plus returns the same object ID for an unfrozen string.
+assert_equal 'true', %q{
+  def jittable_method
+    str = "bar"
+
+    old_obj_id = str.object_id
+    uplus_str = +str
+
+    uplus_str.object_id == old_obj_id
+  end
+  jittable_method
+}
+
+# Test that String unary plus returns a different unfrozen string when given a frozen string
+assert_equal 'false', %q{
+  # Logic needs to be inside an ISEQ, such as a method, for YJIT to compile it
+  def jittable_method
+    frozen_str = "foo".freeze
+
+    old_obj_id = frozen_str.object_id
+    uplus_str = +frozen_str
+
+    uplus_str.object_id == old_obj_id || uplus_str.frozen?
+  end
+
+  jittable_method
+}
+
+# String-subclass objects should behave as expected inside string-interpolation via concatstrings
+assert_equal 'monkeys / monkeys, yo!', %q{
+  class MyString < String
+    # This is a terrible idea in production code, but we'd like YJIT to match CRuby
+    def to_s
+      super + ", yo!"
+    end
+  end
+
+  def jittable_method
+    m = MyString.new('monkeys')
+    "#{m} / #{m.to_s}"
+  end
+
+  jittable_method
+}
+
+# String-subclass objects should behave as expected for string equality
+assert_equal 'false', %q{
+  class MyString < String
+    # This is a terrible idea in production code, but we'd like YJIT to match CRuby
+    def ==(b)
+      "#{self}_" == b
+    end
+  end
+
+  def jittable_method
+    ma = MyString.new("a")
+
+    # Check equality with string-subclass receiver
+    ma == "a" || ma != "a_" ||
+      # Check equality with string receiver
+      "a_" == ma || "a" != ma ||
+      # Check equality between string subclasses
+      ma != MyString.new("a_") ||
+      # Make sure "string always equals itself" check isn't used with overridden equality
+      ma == ma
+  end
+  jittable_method
+}
+
+# Test to_s duplicates a string subclass object but not a string
+assert_equal 'false', %q{
+  class MyString < String; end
+
+  def jittable_method
+    a = "a"
+    ma = MyString.new("a")
+
+    a.object_id != a.to_s.object_id ||
+      ma.object_id == ma.to_s.object_id
+  end
+  jittable_method
+}
+
+# Test freeze on string subclass
+assert_equal 'true', %q{
+  class MyString < String; end
+
+  def jittable_method
+    fma = MyString.new("a").freeze
+
+    # Freezing a string subclass should not duplicate it
+    fma.object_id == fma.freeze.object_id
+  end
+  jittable_method
+}
+
+# Test unary minus on string subclass
+assert_equal 'true', %q{
+  class MyString < String; end
+
+  def jittable_method
+    ma = MyString.new("a")
+    fma = MyString.new("a").freeze
+
+    # Unary minus on frozen string subclass should not duplicate it
+    fma.object_id == (-fma).object_id &&
+      # Unary minus on unfrozen string subclass should duplicate it
+      ma.object_id != (-ma).object_id
+  end
+  jittable_method
+}
+
+# Test unary plus on string subclass
+assert_equal 'true', %q{
+  class MyString < String; end
+
+  def jittable_method
+    fma = MyString.new("a").freeze
+
+    # Unary plus on frozen string subclass should not duplicate it
+    fma.object_id != (+fma).object_id
+  end
+  jittable_method
+}
+
+# Test << operator on string subclass
+assert_equal 'abab', %q{
+  class MyString < String; end
+
+  def jittable_method
+    a = -"a"
+    mb = MyString.new("b")
+
+    buf = String.new
+    mbuf = MyString.new
+
+    buf << a << mb
+    mbuf << a << mb
+
+    buf + mbuf
+  end
+  jittable_method
+}
+
+# test invokebuiltin as used in struct assignment
+assert_equal '123', %q{
+  def foo(obj)
+    obj.foo = 123
+  end
+
+  struct = Struct.new(:foo)
+  obj = struct.new
+  foo(obj)
+  foo(obj)
+}
+
+# test invokebuiltin_delegate as used inside Dir.open
+assert_equal '.', %q{
+  def foo(path)
+    Dir.open(path).path
+  end
+
+  foo(".")
+  foo(".")
+}
+
+# test invokebuiltin_delegate_leave in method called from jit
+assert_normal_exit %q{
+  def foo(obj)
+    obj.clone
+  end
+
+  foo(Object.new)
+  foo(Object.new)
+}
+
+# test invokebuiltin_delegate_leave in method called from cfunc
+assert_normal_exit %q{
+  def foo(obj)
+    [obj].map(&:clone)
+  end
+
+  foo(Object.new)
+  foo(Object.new)
+}
+
+# defining TrueClass#!
+assert_equal '[false, false, :ok]', %q{
+  def foo(obj)
+    !obj
+  end
+
+  x = foo(true)
+  y = foo(true)
+
+  class TrueClass
+    def !
+      :ok
+    end
+  end
+
+  z = foo(true)
+
+  [x, y, z]
+}
+
+# defining FalseClass#!
+assert_equal '[true, true, :ok]', %q{
+  def foo(obj)
+    !obj
+  end
+
+  x = foo(false)
+  y = foo(false)
+
+  class FalseClass
+    def !
+      :ok
+    end
+  end
+
+  z = foo(false)
+
+  [x, y, z]
+}
+
+# defining NilClass#!
+assert_equal '[true, true, :ok]', %q{
+  def foo(obj)
+    !obj
+  end
+
+  x = foo(nil)
+  y = foo(nil)
+
+  class NilClass
+    def !
+      :ok
+    end
+  end
+
+  z = foo(nil)
+
+  [x, y, z]
+}
+
+# polymorphic opt_not
+assert_equal '[true, true, false, false, false, false, false]', %q{
+  def foo(obj)
+    !obj
+  end
+
+  foo(0)
+  [foo(nil), foo(false), foo(true), foo([]), foo(0), foo(4.2), foo(:sym)]
+}
+
+# getlocal with 2 levels
+assert_equal '7', %q{
+  def foo(foo, bar)
+    while foo > 0
+      while bar > 0
+        return foo + bar
+      end
+    end
+  end
+
+  foo(5,2)
+  foo(5,2)
+}
+
+# test pattern matching
+assert_equal '[:ok, :ok]', %q{
+  class C
+    def destructure_keys
+      {}
+    end
+  end
+
+  pattern_match = ->(i) do
+    case i
+    in a: 0
+      :ng
+    else
+      :ok
+    end
+  end
+
+  [{}, C.new].map(&pattern_match)
+}
+
+# Call to object with singleton
+assert_equal '123', %q{
+  obj = Object.new
+  def obj.foo
+    123
+  end
+
+  def foo(obj)
+    obj.foo()
+  end
+
+  foo(obj)
+  foo(obj)
+}
+
+# Call method on an object that has a non-material
+# singleton class.
+# TODO: assert that it takes no side exits? This
+# test case revealed that we were taking exits unnecessarily.
+assert_normal_exit %q{
+  def foo(obj)
+    obj.itself
+  end
+
+  o = Object.new.singleton_class
+  foo(o)
+  foo(o)
+}
+
+# Call to singleton class
+assert_equal '123', %q{
+  class Foo
+    def self.foo
+      123
+    end
+  end
+
+  def foo(obj)
+    obj.foo()
+  end
+
+  foo(Foo)
+  foo(Foo)
+}
+
+# invokesuper edge case
+assert_equal '[:A, [:A, :B]]', %q{
+  class B
+    def foo = :B
+  end
+
+  class A < B
+    def foo = [:A, super()]
+  end
+
+  A.new.foo
+  A.new.foo # compile A#foo
+
+  class C < A
+    define_method(:bar, A.instance_method(:foo))
+  end
+
+  C.new.bar
+}
+
+# Same invokesuper bytecode, multiple destinations
+assert_equal '[:Forward, :SecondTerminus]', %q{
+  module Terminus
+    def foo = :Terminus
+  end
+
+  module SecondTerminus
+    def foo = :SecondTerminus
+  end
+
+
+  module Forward
+    def foo = [:Forward, super]
+  end
+
+  class B
+    include SecondTerminus
+  end
+
+  class A < B
+    include Terminus
+    include Forward
+  end
+
+  A.new.foo
+  A.new.foo # compile
+
+  class B
+    include Forward
+    alias bar foo
+  end
+
+  # A.ancestors.take(5) == [A, Forward, Terminus, B, Forward, SecondTerminus]
+
+  A.new.bar
+}
+
+# invokesuper calling into itself
+assert_equal '[:B, [:B, :m]]', %q{
+  module M
+    def foo = :m
+  end
+
+  class B
+    include M
+    def foo = [:B, super]
+  end
+
+  ins = B.new
+  ins.singleton_class # materialize the singleton class
+  ins.foo
+  ins.foo # compile
+
+  ins.singleton_class.define_method(:bar, B.instance_method(:foo))
+  ins.bar
+}
+
+# invokesuper changed ancestor
+assert_equal '[:A, [:M, :B]]', %q{
+  class B
+    def foo
+      :B
+    end
+  end
+
+  class A < B
+    def foo
+      [:A, super]
+    end
+  end
+
+  module M
+    def foo
+      [:M, super]
+    end
+  end
+
+  ins = A.new
+  ins.foo
+  ins.foo
+  A.include(M)
+  ins.foo
+}
+
+# invokesuper changed ancestor via prepend
+assert_equal '[:A, [:M, :B]]', %q{
+  class B
+    def foo
+      :B
+    end
+  end
+
+  class A < B
+    def foo
+      [:A, super]
+    end
+  end
+
+  module M
+    def foo
+      [:M, super]
+    end
+  end
+
+  ins = A.new
+  ins.foo
+  ins.foo
+  B.prepend(M)
+  ins.foo
+}
+
+# invokesuper replaced method
+assert_equal '[:A, :Btwo]', %q{
+  class B
+    def foo
+      :B
+    end
+  end
+
+  class A < B
+    def foo
+      [:A, super]
+    end
+  end
+
+  ins = A.new
+  ins.foo
+  ins.foo
+  class B
+    def foo
+      :Btwo
+    end
+  end
+  ins.foo
+}
+
+# Call to fixnum
+assert_equal '[true, false]', %q{
+  def is_odd(obj)
+    obj.odd?
+  end
+
+  is_odd(1)
+  is_odd(1)
+
+  [is_odd(123), is_odd(456)]
+}
+
+# Call to bignum
+assert_equal '[true, false]', %q{
+  def is_odd(obj)
+    obj.odd?
+  end
+
+  bignum = 99999999999999999999
+  is_odd(bignum)
+  is_odd(bignum)
+
+  [is_odd(bignum), is_odd(bignum+1)]
+}
+
+# Call to fixnum and bignum
+assert_equal '[true, false, true, false]', %q{
+  def is_odd(obj)
+    obj.odd?
+  end
+
+  bignum = 99999999999999999999
+  is_odd(bignum)
+  is_odd(bignum)
+  is_odd(123)
+  is_odd(123)
+
+  [is_odd(123), is_odd(456), is_odd(bignum), is_odd(bignum+1)]
+}
+
+# Call to static and dynamic symbol
+assert_equal 'bar', %q{
+  def to_string(obj)
+    obj.to_s
+  end
+
+  to_string(:foo)
+  to_string(:foo)
+  to_string((-"bar").to_sym)
+  to_string((-"bar").to_sym)
+}
+
+# Call to flonum and heap float
+assert_equal '[nil, nil, nil, 1]', %q{
+  def is_inf(obj)
+    obj.infinite?
+  end
+
+  is_inf(0.0)
+  is_inf(0.0)
+  is_inf(1e256)
+  is_inf(1e256)
+
+  [
+    is_inf(0.0),
+    is_inf(1.0),
+    is_inf(1e256),
+    is_inf(1.0/0.0)
+  ]
+}
+
+assert_equal '[1, 2, 3, 4, 5]', %q{
+  def splatarray
+    [*(1..5)]
+  end
+
+  splatarray
+  splatarray
+}
+
+assert_equal '[1, 1, 2, 1, 2, 3]', %q{
+  def expandarray
+    arr = [1, 2, 3]
+
+    a, = arr
+    b, c, = arr
+    d, e, f = arr
+
+    [a, b, c, d, e, f]
+  end
+
+  expandarray
+  expandarray
+}
+
+assert_equal '[1, 1]', %q{
+  def expandarray_useless_splat
+    arr = (1..10).to_a
+
+    a, * = arr
+    b, (*) = arr
+
+    [a, b]
+  end
+
+  expandarray_useless_splat
+  expandarray_useless_splat
+}
+
+assert_equal '[:not_heap, nil, nil]', %q{
+  def expandarray_not_heap
+    a, b, c = :not_heap
+    [a, b, c]
+  end
+
+  expandarray_not_heap
+  expandarray_not_heap
+}
+
+assert_equal '[:not_array, nil, nil]', %q{
+  def expandarray_not_array(obj)
+    a, b, c = obj
+    [a, b, c]
+  end
+
+  obj = Object.new
+  def obj.to_ary
+    [:not_array]
+  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]
+    [a, b, c]
+  end
+
+  expandarray_rhs_too_small
+  expandarray_rhs_too_small
+}
+
+assert_equal '[1, [2]]', %q{
+  def expandarray_splat
+    a, *b = [1, 2]
+    [a, b]
+  end
+
+  expandarray_splat
+  expandarray_splat
+}
+
+assert_equal '2', %q{
+  def expandarray_postarg
+    *, a = [1, 2]
+    a
+  end
+
+  expandarray_postarg
+  expandarray_postarg
+}
+
+assert_equal '10', %q{
+  obj = Object.new
+  val = nil
+  obj.define_singleton_method(:to_ary) { val = 10; [] }
+
+  def expandarray_always_call_to_ary(object)
+    * = object
+  end
+
+  expandarray_always_call_to_ary(obj)
+  expandarray_always_call_to_ary(obj)
+
+  val
+}
+
+# regression test of local type change
+assert_equal '1.1', %q{
+def bar(baz, quux)
+  if baz.integer?
+    baz, quux = quux, nil
+  end
+  baz.to_s
+end
+
+bar(123, 1.1)
+bar(123, 1.1)
+}
+
+# test enabling a line TracePoint in a C method call
+assert_equal '[[:line, true]]', %q{
+  events = []
+  events.instance_variable_set(
+    :@tp,
+    TracePoint.new(:line) { |tp| events << [tp.event, tp.lineno] if tp.path == __FILE__ }
+  )
+  def events.to_str
+    @tp.enable; ''
+  end
+
+  # Stay in generated code while enabling tracing
+  def events.compiled(obj)
+    String(obj)
+    @tp.disable; __LINE__
+  end
+
+  line = events.compiled(events)
+  events[0][-1] = (events[0][-1] == line)
+
+  events
+}
+
+# test enabling a c_return TracePoint in a C method call
+assert_equal '[[:c_return, :String, :string_alias, "events_to_str"]]', %q{
+  events = []
+  events.instance_variable_set(:@tp, TracePoint.new(:c_return) { |tp| events << [tp.event, tp.method_id, tp.callee_id, tp.return_value] })
+  def events.to_str
+    @tp.enable; 'events_to_str'
+  end
+
+  # Stay in generated code while enabling tracing
+  alias string_alias String
+  def events.compiled(obj)
+    string_alias(obj)
+    @tp.disable
+  end
+
+  events.compiled(events)
+
+  events
+} unless defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled? # MJIT calls extra Ruby methods
+
+# test enabling a TracePoint that targets a particular line in a C method call
+assert_equal '[true]', %q{
+  events = []
+  events.instance_variable_set(:@tp, TracePoint.new(:line) { |tp| events << tp.lineno })
+  def events.to_str
+    @tp.enable(target: method(:compiled))
+    ''
+  end
+
+  # Stay in generated code while enabling tracing
+  def events.compiled(obj)
+    String(obj)
+    __LINE__
+  end
+
+  line = events.compiled(events)
+  events[0] = (events[0] == line)
+
+  events
+}
+
+# test enabling tracing in the middle of splatarray
+assert_equal '[true]', %q{
+  events = []
+  obj = Object.new
+  obj.instance_variable_set(:@tp, TracePoint.new(:line) { |tp| events << tp.lineno })
+  def obj.to_a
+    @tp.enable(target: method(:compiled))
+    []
+  end
+
+  # Enable tracing in the middle of the splatarray instruction
+  def obj.compiled(obj)
+    * = *obj
+    __LINE__
+  end
+
+  obj.compiled([])
+  line = obj.compiled(obj)
+  events[0] = (events[0] == line)
+
+  events
+}
+
+# test enabling tracing in the middle of opt_aref. Different since the codegen
+# for it ends in a jump.
+assert_equal '[true]', %q{
+  def lookup(hash, tp)
+    hash[42]
+    tp.disable; __LINE__
+  end
+
+  lines = []
+  tp = TracePoint.new(:line) { lines << _1.lineno if _1.path == __FILE__ }
+
+  lookup(:foo, tp)
+  lookup({}, tp)
+
+  enable_tracing_on_missing = Hash.new { tp.enable }
+
+  expected_line = lookup(enable_tracing_on_missing, tp)
+
+  lines[0] = true if lines[0] == expected_line
+
+  lines
+}
+
+# test enabling c_call tracing before compiling
+assert_equal '[[:c_call, :itself]]', %q{
+  def shouldnt_compile
+    itself
+  end
+
+  events = []
+  tp = TracePoint.new(:c_call) { |tp| events << [tp.event, tp.method_id] }
+
+  # assume first call compiles
+  tp.enable { shouldnt_compile }
+
+  events
+} unless defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled? # MJIT calls extra Ruby methods
+
+# test enabling c_return tracing before compiling
+assert_equal '[[:c_return, :itself, main]]', %q{
+  def shouldnt_compile
+    itself
+  end
+
+  events = []
+  tp = TracePoint.new(:c_return) { |tp| events << [tp.event, tp.method_id, tp.return_value] }
+
+  # assume first call compiles
+  tp.enable { shouldnt_compile }
+
+  events
+} unless defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled? # MJIT calls extra Ruby methods
+
+# 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
+    Fiber.yield
+    42
+  end
+
+  events = []
+  tp = TracePoint.new(:return) { events << [_1.event, _1.return_value] }
+  # assume first call compiles
+  fiber = Fiber.new { traced_method }
+  fiber.resume
+  tp.enable(target: method(:traced_method))
+  fiber.resume
+
+  events
+}
+
+# test compiling on non-tracing ractor then running on a tracing one
+assert_equal '[:itself]', %q{
+  def traced_method
+    itself
+  end
+
+  tracing_ractor = Ractor.new do
+    # 1: start tracing
+    events = []
+    tp = TracePoint.new(:c_call) { events << _1.method_id }
+    tp.enable
+    Ractor.yield(nil)
+
+    # 3: run compiled method on tracing ractor
+    Ractor.yield(nil)
+    traced_method
+
+    events
+  ensure
+    tp&.disable
+  end
+
+  tracing_ractor.take
+
+  # 2: compile on non tracing ractor
+  traced_method
+
+  tracing_ractor.take
+  tracing_ractor.take
+}
+
+# Try to hit a lazy branch stub while another ractor enables tracing
+assert_equal '42', %q{
+  def compiled(arg)
+    if arg
+      arg + 1
+    else
+      itself
+      itself
+    end
+  end
+
+  ractor = Ractor.new do
+    compiled(false)
+    Ractor.yield(nil)
+    compiled(41)
+  end
+
+  tp = TracePoint.new(:line) { itself }
+  ractor.take
+  tp.enable
+
+  ractor.take
+}
+
+# Test equality with changing types
+assert_equal '[true, false, false, false]', %q{
+  def eq(a, b)
+    a == b
+  end
+
+  [
+    eq("foo", "foo"),
+    eq("foo", "bar"),
+    eq(:foo, "bar"),
+    eq("foo", :bar)
+  ]
+}
+
+# Redefined String eq
+assert_equal 'true', %q{
+  class String
+    def ==(other)
+      true
+    end
+  end
+
+  def eq(a, b)
+    a == b
+  end
+
+  eq("foo", "bar")
+  eq("foo", "bar")
+}
+
+# Redefined Integer eq
+assert_equal 'true', %q{
+  class Integer
+    def ==(other)
+      true
+    end
+  end
+
+  def eq(a, b)
+    a == b
+  end
+
+  eq(1, 2)
+  eq(1, 2)
+}
+
+# aset on array with invalid key
+assert_normal_exit %q{
+  def foo(arr)
+    arr[:foo] = 123
+  end
+
+  foo([1]) rescue nil
+  foo([1]) rescue nil
+}
+
+# test ractor exception on when setting ivar
+assert_equal '42',  %q{
+  class A
+    def self.foo
+      _foo = 1
+      _bar = 2
+      begin
+        @bar = _foo + _bar
+      rescue Ractor::IsolationError
+        42
+      end
+    end
+  end
+
+  A.foo
+  A.foo
+
+  Ractor.new { A.foo }.take
+}
+
+assert_equal '["plain", "special", "sub", "plain"]', %q{
+  def foo(arg)
+    arg.to_s
+  end
+
+  class Sub < String
+  end
+
+  special = String.new("special")
+  special.singleton_class
+
+  [
+    foo("plain"),
+    foo(special),
+    foo(Sub.new("sub")),
+    foo("plain")
+  ]
+}
+
+assert_equal '["sub", "sub"]', %q{
+  def foo(arg)
+    arg.to_s
+  end
+
+  class Sub < String
+    def to_s
+      super
+    end
+  end
+
+  sub = Sub.new("sub")
+
+  [foo(sub), foo(sub)]
+}
+
+assert_equal '[1]', %q{
+  def kwargs(value:)
+    value
+  end
+
+  5.times.map { kwargs(value: 1) }.uniq
+}
+
+assert_equal '[:ok]', %q{
+  def kwargs(value:)
+    value
+  end
+
+  5.times.map { kwargs() rescue :ok }.uniq
+}
+
+assert_equal '[:ok]', %q{
+  def kwargs(a:, b: nil)
+    value
+  end
+
+  5.times.map { kwargs(b: 123) rescue :ok }.uniq
+}
+
+assert_equal '[[1, 2]]', %q{
+  def kwargs(left:, right:)
+    [left, right]
+  end
+
+  5.times.flat_map do
+    [
+      kwargs(left: 1, right: 2),
+      kwargs(right: 2, left: 1)
+    ]
+  end.uniq
+}
+
+assert_equal '[[1, 2]]', %q{
+  def kwargs(lead, kwarg:)
+    [lead, kwarg]
+  end
+
+  5.times.map { kwargs(1, kwarg: 2) }.uniq
+}
+
+# optional and keyword args
+assert_equal '[[1, 2, 3]]', %q{
+  def opt_and_kwargs(a, b=2, c: nil)
+    [a,b,c]
+  end
+
+  5.times.map { opt_and_kwargs(1, c: 3) }.uniq
+}
+
+assert_equal '[[1, 2, 3]]', %q{
+  def opt_and_kwargs(a, b=nil, c: nil)
+    [a,b,c]
+  end
+
+  5.times.map { opt_and_kwargs(1, 2, c: 3) }.uniq
+}
+
+# Bug #18453
+assert_equal '[[1, nil, 2]]', %q{
+  def opt_and_kwargs(a = {}, b: nil, c: nil)
+    [a, b, c]
+  end
+
+  5.times.map { opt_and_kwargs(1, c: 2) }.uniq
+}
+
+assert_equal '[[{}, nil, 1]]', %q{
+  def opt_and_kwargs(a = {}, b: nil, c: nil)
+    [a, b, c]
+  end
+
+  5.times.map { opt_and_kwargs(c: 1) }.uniq
+}
+
+# leading and keyword arguments are swapped into the right order
+assert_equal '[[1, 2, 3, 4, 5, 6]]', %q{
+  def kwargs(five, six, a:, b:, c:, d:)
+    [a, b, c, d, five, six]
+  end
+
+  5.times.flat_map do
+    [
+      kwargs(5, 6, a: 1, b: 2, c: 3, d: 4),
+      kwargs(5, 6, a: 1, b: 2, d: 4, c: 3),
+      kwargs(5, 6, a: 1, c: 3, b: 2, d: 4),
+      kwargs(5, 6, a: 1, c: 3, d: 4, b: 2),
+      kwargs(5, 6, a: 1, d: 4, b: 2, c: 3),
+      kwargs(5, 6, a: 1, d: 4, c: 3, b: 2),
+      kwargs(5, 6, b: 2, a: 1, c: 3, d: 4),
+      kwargs(5, 6, b: 2, a: 1, d: 4, c: 3),
+      kwargs(5, 6, b: 2, c: 3, a: 1, d: 4),
+      kwargs(5, 6, b: 2, c: 3, d: 4, a: 1),
+      kwargs(5, 6, b: 2, d: 4, a: 1, c: 3),
+      kwargs(5, 6, b: 2, d: 4, c: 3, a: 1),
+      kwargs(5, 6, c: 3, a: 1, b: 2, d: 4),
+      kwargs(5, 6, c: 3, a: 1, d: 4, b: 2),
+      kwargs(5, 6, c: 3, b: 2, a: 1, d: 4),
+      kwargs(5, 6, c: 3, b: 2, d: 4, a: 1),
+      kwargs(5, 6, c: 3, d: 4, a: 1, b: 2),
+      kwargs(5, 6, c: 3, d: 4, b: 2, a: 1),
+      kwargs(5, 6, d: 4, a: 1, b: 2, c: 3),
+      kwargs(5, 6, d: 4, a: 1, c: 3, b: 2),
+      kwargs(5, 6, d: 4, b: 2, a: 1, c: 3),
+      kwargs(5, 6, d: 4, b: 2, c: 3, a: 1),
+      kwargs(5, 6, d: 4, c: 3, a: 1, b: 2),
+      kwargs(5, 6, d: 4, c: 3, b: 2, a: 1)
+    ]
+  end.uniq
+}
+
+# implicit hashes get skipped and don't break compilation
+assert_equal '[[:key]]', %q{
+  def implicit(hash)
+    hash.keys
+  end
+
+  5.times.map { implicit(key: :value) }.uniq
+}
+
+# default values on keywords don't mess up argument order
+assert_equal '[2]', %q{
+  def default_value
+    1
+  end
+
+  def default_expression(value: default_value)
+    value
+  end
+
+  5.times.map { default_expression(value: 2) }.uniq
+}
+
+# constant default values on keywords
+assert_equal '[3]', %q{
+  def default_expression(value: 3)
+    value
+  end
+
+  5.times.map { default_expression }.uniq
+}
+
+# non-constant default values on keywords
+assert_equal '[3]', %q{
+  def default_value
+    3
+  end
+
+  def default_expression(value: default_value)
+    value
+  end
+
+  5.times.map { default_expression }.uniq
+}
+
+# reordered optional kwargs
+assert_equal '[[100, 1]]', %q{
+  def foo(capacity: 100, max: nil)
+    [capacity, max]
+  end
+
+  5.times.map { foo(max: 1) }.uniq
+}
+
+# invalid lead param
+assert_equal 'ok', %q{
+  def bar(baz: 2)
+    baz
+  end
+
+  def foo
+    bar(1, baz: 123)
+  end
+
+  begin
+    foo
+    foo
+  rescue ArgumentError => e
+    print "ok"
+  end
+}
+
+# reordered required kwargs
+assert_equal '[[1, 2, 3, 4]]', %q{
+  def foo(default1: 1, required1:, default2: 3, required2:)
+    [default1, required1, default2, required2]
+  end
+
+  5.times.map { foo(required1: 2, required2: 4) }.uniq
+}
+
+# reordered default expression kwargs
+assert_equal '[[:one, :two, 3]]', %q{
+  def foo(arg1: (1+0), arg2: (2+0), arg3: (3+0))
+    [arg1, arg2, arg3]
+  end
+
+  5.times.map { foo(arg2: :two, arg1: :one) }.uniq
+}
+
+# complex kwargs
+assert_equal '[[1, 2, 3, 4]]', %q{
+  def foo(required:, specified: 999, simple_default: 3, complex_default: "4".to_i)
+    [required, specified, simple_default, complex_default]
+  end
+
+  5.times.map { foo(specified: 2, required: 1) }.uniq
+}
+
+# cfunc kwargs
+assert_equal '{:foo=>123}', %q{
+  def foo(bar)
+    bar.store(:value, foo: 123)
+    bar[:value]
+  end
+
+  foo({})
+  foo({})
+}
+
+# cfunc kwargs
+assert_equal '{:foo=>123}', %q{
+  def foo(bar)
+    bar.replace(foo: 123)
+  end
+
+  foo({})
+  foo({})
+}
+
+# cfunc kwargs
+assert_equal '{:foo=>123, :bar=>456}', %q{
+  def foo(bar)
+    bar.replace(foo: 123, bar: 456)
+  end
+
+  foo({})
+  foo({})
+}
+
+# variadic cfunc kwargs
+assert_equal '{:foo=>123}', %q{
+  def foo(bar)
+    bar.merge(foo: 123)
+  end
+
+  foo({})
+  foo({})
+}
+
+# optimized cfunc kwargs
+assert_equal 'false', %q{
+  def foo
+    :foo.eql?(foo: :foo)
+  end
+
+  foo
+  foo
+}
+
+# attr_reader on frozen object
+assert_equal 'false', %q{
+  class Foo
+    attr_reader :exception
+
+    def failed?
+      !exception.nil?
+    end
+  end
+
+  foo = Foo.new.freeze
+  foo.failed?
+  foo.failed?
+}
+
+# regression test for doing kwarg shuffle before checking for interrupts
+assert_equal 'ok', %q{
+  def new_media_drop(attributes:, product_drop:, context:, sources:)
+    nil.nomethod rescue nil # force YJIT to bail to side exit
+
+    [attributes, product_drop, context, sources]
+  end
+
+  def load_medias(product_drop: nil, raw_medias:, context:)
+    raw_medias.map do |raw_media|
+      case new_media_drop(context: context, attributes: raw_media, product_drop: product_drop, sources: [])
+      in [Hash, ProductDrop, Context, Array]
+      else
+        raise "bad shuffle"
+      end
+    end
+  end
+
+  class Context; end
+
+  class ProductDrop
+    attr_reader :title
+    def initialize(title)
+      @title = title
+    end
+  end
+
+  # Make a thread so we have thread switching interrupts
+  th = Thread.new do
+    while true; end
+  end
+  1_000.times do |i|
+    load_medias(product_drop: ProductDrop.new("foo"), raw_medias: [{}, {}], context: Context.new)
+  end
+  th.kill.join
+
+  :ok
+}
+
+# regression test for tracing attr_accessor methods.
+assert_equal "true", %q{
+    c = Class.new do
+      attr_accessor :x
+      alias y x
+      alias y= x=
+    end
+    obj = c.new
+
+    ar_meth = obj.method(:x)
+    aw_meth = obj.method(:x=)
+    aar_meth = obj.method(:y)
+    aaw_meth = obj.method(:y=)
+    events = []
+    trace = TracePoint.new(:c_call, :c_return){|tp|
+      next if tp.path != __FILE__
+      next if tp.method_id == :call
+      case tp.event
+      when :c_call
+        events << [tp.event, tp.method_id, tp.callee_id]
+      when :c_return
+        events << [tp.event, tp.method_id, tp.callee_id, tp.return_value]
+      end
+    }
+    test_proc = proc do
+      obj.x = 1
+      obj.x
+      obj.y = 2
+      obj.y
+      aw_meth.call(1)
+      ar_meth.call
+      aaw_meth.call(2)
+      aar_meth.call
+    end
+    test_proc.call # populate call caches
+    trace.enable(&test_proc)
+    expected = [
+      [:c_call, :x=, :x=],
+      [:c_return, :x=, :x=, 1],
+      [:c_call, :x, :x],
+      [:c_return, :x, :x, 1],
+      [:c_call, :x=, :y=],
+      [:c_return, :x=, :y=, 2],
+      [:c_call, :x, :y],
+      [:c_return, :x, :y, 2],
+    ] * 2
+
+    expected == events
+}
+
+# duphash
+assert_equal '{:foo=>123}', %q{
+  def foo
+    {foo: 123}
+  end
+
+  foo
+  foo
+}
+
+# newhash
+assert_equal '{:foo=>2}', %q{
+  def foo
+    {foo: 1+1}
+  end
+
+  foo
+  foo
+}
+
+# block invalidation edge case
+assert_equal 'undef', %q{
+  class A
+    def foo(arg)
+      arg.times { A.remove_method(:bar) }
+      self
+    end
+
+    def bar
+      4
+    end
+
+    def use(arg)
+      # two consecutive sends. When bar is removed, the return address
+      # for calling it is already on foo's control frame
+      foo(arg).bar
+    rescue NoMethodError
+      :undef
+    end
+  end
+
+  A.new.use 0
+  A.new.use 0
+  A.new.use 1
+}
+
+# block invalidation edge case
+assert_equal 'ok', %q{
+  class A
+    Good = :ng
+    def foo(arg)
+      arg.times { A.const_set(:Good, :ok) }
+      self
+    end
+
+    def id(arg)
+      arg
+    end
+
+    def use(arg)
+      # send followed by an opt_getinlinecache.
+      # The return address remains on the control frame
+      # when opt_getinlinecache is invalidated.
+      foo(arg).id(Good)
+    end
+  end
+
+  A.new.use 0
+  A.new.use 0
+  A.new.use 1
+}
+
+assert_equal 'ok', %q{
+  # test hitting a branch stub when out of memory
+  def nimai(jita)
+    if jita
+      :ng
+    else
+      :ok
+    end
+  end
+
+  nimai(true)
+  nimai(true)
+
+  RubyVM::YJIT.simulate_oom! if defined?(RubyVM::YJIT)
+
+  nimai(false)
+}
+
+assert_equal 'new', %q{
+  # test block invalidation while out of memory
+  def foo
+    :old
+  end
+
+  def test
+    foo
+  end
+
+  def bar
+    :bar
+  end
+
+
+  test
+  test
+
+  RubyVM::YJIT.simulate_oom! if defined?(RubyVM::YJIT)
+
+  # Old simulat_omm! leaves one byte of space and this fills it up
+  bar
+  bar
+
+  def foo
+    :new
+  end
+
+  test
+}
+
+assert_equal 'ok', %q{
+  # Try to compile new method while OOM
+  def foo
+    :ok
+  end
+
+  RubyVM::YJIT.simulate_oom! if defined?(RubyVM::YJIT)
+
+  foo
+  foo
+}
+
+# struct aref embedded
+assert_equal '2', %q{
+  def foo(s)
+    s.foo
+  end
+
+  S = Struct.new(:foo)
+  foo(S.new(1))
+  foo(S.new(2))
+}
+
+# struct aref non-embedded
+assert_equal '4', %q{
+  def foo(s)
+    s.d
+  end
+
+  S = Struct.new(:a, :b, :c, :d, :e)
+  foo(S.new(1,2,3,4,5))
+  foo(S.new(1,2,3,4,5))
+}
+
+# struct aset embedded
+assert_equal '123', %q{
+  def foo(s)
+    s.foo = 123
+  end
+
+  s = Struct.new(:foo).new
+  foo(s)
+  s = Struct.new(:foo).new
+  foo(s)
+  s.foo
+}
+
+# struct aset non-embedded
+assert_equal '[1, 2, 3, 4, 5]', %q{
+  def foo(s)
+    s.a = 1
+    s.b = 2
+    s.c = 3
+    s.d = 4
+    s.e = 5
+  end
+
+  S = Struct.new(:a, :b, :c, :d, :e)
+  s = S.new
+  foo(s)
+  s = S.new
+  foo(s)
+  [s.a, s.b, s.c, s.d, s.e]
+}
+
+# struct aref too many args
+assert_equal 'ok', %q{
+  def foo(s)
+    s.foo(:bad)
+  end
+
+  s = Struct.new(:foo).new
+  foo(s) rescue :ok
+  foo(s) rescue :ok
+}
+
+# struct aset too many args
+assert_equal 'ok', %q{
+  def foo(s)
+    s.set_foo(123, :bad)
+  end
+
+  s = Struct.new(:foo) do
+    alias :set_foo :foo=
+  end
+  foo(s) rescue :ok
+  foo(s) rescue :ok
+}
+
+# File.join is a cfunc accepting variable arguments as a Ruby array (argc = -2)
+assert_equal 'foo/bar', %q{
+  def foo
+    File.join("foo", "bar")
+  end
+
+  foo
+  foo
+}
+
+# File.join is a cfunc accepting variable arguments as a Ruby array (argc = -2)
+assert_equal '', %q{
+  def foo
+    File.join()
+  end
+
+  foo
+  foo
+}
+
+# Make sure we're correctly reading RStruct's as.ary union for embedded RStructs
+assert_equal '3,12', %q{
+  pt_struct = Struct.new(:x, :y)
+  p = pt_struct.new(3, 12)
+  def pt_inspect(pt)
+    "#{pt.x},#{pt.y}"
+  end
+
+  # Make sure pt_inspect is JITted
+  10.times { pt_inspect(p) }
+
+  # Make sure it's returning '3,12' instead of e.g. '3,false'
+  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()
+        [1, 2] in [Integer, String]
+    end
+    function()
+}
+
+# opt_send_without_block (VM_METHOD_TYPE_ATTRSET)
+assert_equal 'foo', %q{
+    class Foo
+      attr_writer :foo
+
+      def foo()
+        self.foo = "foo"
+      end
+    end
+    foo = Foo.new
+    foo.foo
+}
+
+# anytostring, intern
+assert_equal 'true', %q{
+    def foo()
+      :"#{true}"
+    end
+    foo()
+}
+
+# toregexp, objtostring
+assert_equal '/true/', %q{
+    def foo()
+      /#{true}/
+    end
+    foo().inspect
+}
+
+# concatstrings, objtostring
+assert_equal '9001', %q{
+    def foo()
+      "#{9001}"
+    end
+    foo()
+}
+
+# opt_send_without_block (VM_METHOD_TYPE_CFUNC)
+assert_equal 'nil', %q{
+    def foo
+      nil.inspect # argc: 0
+    end
+    foo
+}
+assert_equal '4', %q{
+    def foo
+      2.pow(2) # argc: 1
+    end
+    foo
+}
+assert_equal 'aba', %q{
+    def foo
+      "abc".tr("c", "a") # argc: 2
+    end
+    foo
+}
+assert_equal 'true', %q{
+    def foo
+      respond_to?(:inspect) # argc: -1
+    end
+    foo
+}
+assert_equal '["a", "b"]', %q{
+    def foo
+      "a\nb".lines(chomp: true) # kwargs
+    end
+    foo
+}
+
+# invokebuiltin
+assert_equal '123', %q{
+  def foo(obj)
+    obj.foo = 123
+  end
+
+  struct = Struct.new(:foo)
+  obj = struct.new
+  foo(obj)
+}
+
+# invokebuiltin_delegate
+assert_equal '.', %q{
+  def foo(path)
+    Dir.open(path).path
+  end
+  foo(".")
+}
+
+# opt_invokebuiltin_delegate_leave
+assert_equal '[0]', %q{"\x00".unpack("c")}
+
+# opt_send_without_block (VM_METHOD_TYPE_ISEQ)
+assert_equal '1', %q{
+  def foo = 1
+  def bar = foo
+  bar
+}
+assert_equal '[1, 2, 3]', %q{
+  def foo(a, b) = [1, a, b]
+  def bar = foo(2, 3)
+  bar
+}
+assert_equal '[1, 2, 3, 4, 5, 6]', %q{
+  def foo(a, b, c:, d:, e: 0, f: 6) = [a, b, c, d, e, f]
+  def bar = foo(1, 2, c: 3, d: 4, e: 5)
+  bar
+}
+assert_equal '[1, 2, 3, 4]', %q{
+  def foo(a, b = 2) = [a, b]
+  def bar = foo(1) + foo(3, 4)
+  bar
+}
+
+assert_equal '1', %q{
+  def foo(a) = a
+  def bar = foo(1) { 2 }
+  bar
+}
+assert_equal '[1, 2]', %q{
+  def foo(a, &block) = [a, block.call]
+  def bar = foo(1) { 2 }
+  bar
+}
+
+# opt_send_without_block (VM_METHOD_TYPE_IVAR)
+assert_equal 'foo', %q{
+  class Foo
+    attr_reader :foo
+
+    def initialize
+      @foo = "foo"
+    end
+  end
+  Foo.new.foo
+}
+
+# opt_send_without_block (VM_METHOD_TYPE_OPTIMIZED)
+assert_equal 'foo', %q{
+  Foo = Struct.new(:bar)
+  Foo.new("bar").bar = "foo"
+}
+assert_equal 'foo', %q{
+  Foo = Struct.new(:bar)
+  Foo.new("foo").bar
+}
+
+# getblockparamproxy
+assert_equal 'foo', %q{
+  def foo(&block)
+    block.call
+  end
+  foo { "foo" }
+}
+
+# getblockparam
+assert_equal 'foo', %q{
+  def foo(&block)
+    block
+  end
+  foo { "foo" }.call
+}
+
+assert_equal '[1, 2]', %q{
+  def foo
+    x = [2]
+    [1, *x]
+  end
+
+  foo
+  foo
+}
+
+# respond_to? with changing symbol
+assert_equal 'false', %q{
+  def foo(name)
+    :sym.respond_to?(name)
+  end
+  foo(:to_s)
+  foo(:to_s)
+  foo(:not_exist)
+}
+
+# respond_to? with method being defined
+assert_equal 'true', %q{
+  def foo
+    :sym.respond_to?(:not_yet_defined)
+  end
+  foo
+  foo
+  module Kernel
+    def not_yet_defined = true
+  end
+  foo
+}
+
+# respond_to? with undef method
+assert_equal 'false', %q{
+  module Kernel
+    def to_be_removed = true
+  end
+  def foo
+    :sym.respond_to?(:to_be_removed)
+  end
+  foo
+  foo
+  class Object
+    undef_method :to_be_removed
+  end
+  foo
+}
+
+# respond_to? with respond_to_missing?
+assert_equal 'true', %q{
+  class Foo
+  end
+  def foo(x)
+    x.respond_to?(:bar)
+  end
+  foo(Foo.new)
+  foo(Foo.new)
+  class Foo
+    def respond_to_missing?(*) = true
+  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 { }
+}
+
+# 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_normal_exit %{
+  class Bug20997
+    def foo(&) = self.class.name(&)
+
+    new.foo
+  end
+}
diff --git a/bootstraptest/test_yjit_30k_ifelse.rb b/bootstraptest/test_yjit_30k_ifelse.rb
new file mode 100644
index 0000000000..c3afa95e4d
--- /dev/null
+++ b/bootstraptest/test_yjit_30k_ifelse.rb