Ruby MJIT (#6028)

5 files changed, 2302 insertions, 0 deletions

diff --git a/lib/mjit/c_32.rb b/lib/mjit/c_32.rb
new file mode 100644
index 0000000000..ee8324ba4d
--- /dev/null
+++ b/lib/mjit/c_32.rb
@@ -0,0 +1,436 @@
+require_relative 'c_type'
+
+module RubyVM::MJIT
+  C = Object.new
+
+  def C.NOT_COMPILED_STACK_SIZE = - 1
+
+  def C.USE_LAZY_LOAD = false
+
+  def C.USE_RVARGC = true
+
+  def C.VM_CALL_KW_SPLAT = ( 0x01 << self.VM_CALL_KW_SPLAT_bit )
+
+  def C.VM_CALL_TAILCALL = ( 0x01 << self.VM_CALL_TAILCALL_bit )
+
+  def C.VM_METHOD_TYPE_CFUNC = 1
+
+  def C.VM_METHOD_TYPE_ISEQ = 0
+
+  def C.VM_CALL_KW_SPLAT_bit = 7
+
+  def C.VM_CALL_TAILCALL_bit = 8
+
+  def C.CALL_DATA
+    @CALL_DATA ||= self.rb_call_data
+  end
+
+  def C.IC
+    @IC ||= self.iseq_inline_constant_cache
+  end
+
+  def C.IVC
+    @IVC ||= self.iseq_inline_iv_cache_entry
+  end
+
+  def C.RB_BUILTIN
+    @RB_BUILTIN ||= self.rb_builtin_function
+  end
+
+  def C.VALUE
+    @VALUE ||= CType::Immediate.new(-5)
+  end
+
+  def C.compile_branch
+    @compile_branch ||= CType::Struct.new(
+      "compile_branch", 8,
+      stack_size: [0, CType::Immediate.new(-4)],
+      finish_p: [32, self._Bool],
+    )
+  end
+
+  def C.compile_status
+    @compile_status ||= CType::Struct.new(
+      "compile_status", 68,
+      success: [0, self._Bool],
+      stack_size_for_pos: [32, CType::Pointer.new { CType::Immediate.new(4) }],
+      local_stack_p: [64, self._Bool],
+      is_entries: [96, CType::Pointer.new { self.iseq_inline_storage_entry }],
+      cc_entries_index: [128, CType::Immediate.new(4)],
+      compiled_iseq: [160, CType::Pointer.new { self.rb_iseq_constant_body }],
+      compiled_id: [192, CType::Immediate.new(4)],
+      compile_info: [224, CType::Pointer.new { self.rb_mjit_compile_info }],
+      merge_ivar_guards_p: [256, self._Bool],
+      ivar_serial: [288, self.rb_serial_t],
+      max_ivar_index: [352, CType::Immediate.new(-4)],
+      inlined_iseqs: [384, CType::Pointer.new { CType::Pointer.new { self.rb_iseq_constant_body } }],
+      inline_context: [416, self.inlined_call_context],
+    )
+  end
+
+  def C.inlined_call_context
+    @inlined_call_context ||= CType::Struct.new(
+      "inlined_call_context", 16,
+      orig_argc: [0, CType::Immediate.new(4)],
+      me: [32, self.VALUE],
+      param_size: [64, CType::Immediate.new(4)],
+      local_size: [96, CType::Immediate.new(4)],
+    )
+  end
+
+  def C.iseq_inline_constant_cache
+    @iseq_inline_constant_cache ||= CType::Struct.new(
+      "iseq_inline_constant_cache", 8,
+      entry: [0, CType::Pointer.new { self.iseq_inline_constant_cache_entry }],
+      segments: [32, CType::Pointer.new { self.ID }],
+    )
+  end
+
+  def C.iseq_inline_constant_cache_entry
+    @iseq_inline_constant_cache_entry ||= CType::Struct.new(
+      "iseq_inline_constant_cache_entry", 20,
+      flags: [0, self.VALUE],
+      value: [32, self.VALUE],
+      _unused1: [64, self.VALUE],
+      _unused2: [96, self.VALUE],
+      ic_cref: [128, CType::Pointer.new { self.rb_cref_t }],
+    )
+  end
+
+  def C.iseq_inline_iv_cache_entry
+    @iseq_inline_iv_cache_entry ||= CType::Struct.new(
+      "iseq_inline_iv_cache_entry", 4,
+      entry: [0, CType::Pointer.new { self.rb_iv_index_tbl_entry }],
+    )
+  end
+
+  def C.iseq_inline_storage_entry
+    @iseq_inline_storage_entry ||= CType::Union.new(
+      "iseq_inline_storage_entry", 8,
+      once: CType::Struct.new(
+        "", 8,
+        running_thread: [0, CType::Pointer.new { self.rb_thread_struct }],
+        value: [32, self.VALUE],
+      ),
+      ic_cache: self.iseq_inline_constant_cache,
+      iv_cache: self.iseq_inline_iv_cache_entry,
+    )
+  end
+
+  def C.mjit_options
+    @mjit_options ||= CType::Struct.new(
+      "mjit_options", 24,
+      on: [0, self._Bool],
+      save_temps: [8, self._Bool],
+      warnings: [16, self._Bool],
+      debug: [24, self._Bool],
+      debug_flags: [32, CType::Pointer.new { CType::Immediate.new(2) }],
+      wait: [64, self._Bool],
+      min_calls: [96, CType::Immediate.new(-4)],
+      verbose: [128, CType::Immediate.new(4)],
+      max_cache_size: [160, CType::Immediate.new(4)],
+    )
+  end
+
+  def C.rb_builtin_function
+    @rb_builtin_function ||= CType::Struct.new(
+      "rb_builtin_function", 20,
+      func_ptr: [0, CType::Pointer.new { CType::Immediate.new(0) }],
+      argc: [32, CType::Immediate.new(4)],
+      index: [64, CType::Immediate.new(4)],
+      name: [96, CType::Pointer.new { CType::Immediate.new(2) }],
+      compiler: [128, CType::Immediate.new(1)],
+    )
+  end
+
+  def C.rb_call_data
+    @rb_call_data ||= CType::Struct.new(
+      "rb_call_data", 8,
+      ci: [0, CType::Pointer.new { self.rb_callinfo }],
+      cc: [32, CType::Pointer.new { self.rb_callcache }],
+    )
+  end
+
+  def C.rb_callable_method_entry_struct
+    @rb_callable_method_entry_struct ||= CType::Struct.new(
+      "rb_callable_method_entry_struct", 20,
+      flags: [0, self.VALUE],
+      defined_class: [32, self.VALUE],
+      def: [64, CType::Pointer.new { self.rb_method_definition_struct }],
+      called_id: [96, self.ID],
+      owner: [128, self.VALUE],
+    )
+  end
+
+  def C.rb_callcache
+    @rb_callcache ||= CType::Struct.new(
+      "rb_callcache", 20,
+      flags: [0, self.VALUE],
+      klass: [32, self.VALUE],
+      cme_: [64, CType::Pointer.new { self.rb_callable_method_entry_struct }],
+      call_: [96, self.vm_call_handler],
+      aux_: [128, CType::Union.new(
+        "", 4,
+        attr_index: CType::Immediate.new(-4),
+        method_missing_reason: self.method_missing_reason,
+        v: self.VALUE,
+      )],
+    )
+  end
+
+  def C.rb_callinfo
+    @rb_callinfo ||= CType::Struct.new(
+      "rb_callinfo", 20,
+      flags: [0, self.VALUE],
+      kwarg: [32, CType::Pointer.new { self.rb_callinfo_kwarg }],
+      mid: [64, self.VALUE],
+      flag: [96, self.VALUE],
+      argc: [128, self.VALUE],
+    )
+  end
+
+  def C.rb_cref_t
+    @rb_cref_t ||= CType::Struct.new(
+      "rb_cref_struct", 20,
+      flags: [0, self.VALUE],
+      refinements: [32, self.VALUE],
+      klass_or_self: [64, self.VALUE],
+      next: [96, CType::Pointer.new { self.rb_cref_struct }],
+      scope_visi: [128, self.rb_scope_visibility_t],
+    )
+  end
+
+  def C.rb_iseq_constant_body
+    @rb_iseq_constant_body ||= CType::Struct.new(
+      "rb_iseq_constant_body", 204,
+      type: [0, self.rb_iseq_type],
+      iseq_size: [32, CType::Immediate.new(-4)],
+      iseq_encoded: [64, CType::Pointer.new { self.VALUE }],
+      param: [96, CType::Struct.new(
+        "", 40,
+        flags: [0, CType::Struct.new(
+          "", 4,
+          has_lead: [0, CType::BitField.new(1, 0)],
+          has_opt: [1, CType::BitField.new(1, 1)],
+          has_rest: [2, CType::BitField.new(1, 2)],
+          has_post: [3, CType::BitField.new(1, 3)],
+          has_kw: [4, CType::BitField.new(1, 4)],
+          has_kwrest: [5, CType::BitField.new(1, 5)],
+          has_block: [6, CType::BitField.new(1, 6)],
+          ambiguous_param0: [7, CType::BitField.new(1, 7)],
+          accepts_no_kwarg: [8, CType::BitField.new(1, 0)],
+          ruby2_keywords: [9, CType::BitField.new(1, 1)],
+        )],
+        size: [32, CType::Immediate.new(-4)],
+        lead_num: [64, CType::Immediate.new(4)],
+        opt_num: [96, CType::Immediate.new(4)],
+        rest_start: [128, CType::Immediate.new(4)],
+        post_start: [160, CType::Immediate.new(4)],
+        post_num: [192, CType::Immediate.new(4)],
+        block_start: [224, CType::Immediate.new(4)],
+        opt_table: [256, CType::Pointer.new { self.VALUE }],
+        keyword: [288, CType::Pointer.new { self.rb_iseq_param_keyword }],
+      )],
+      location: [416, self.rb_iseq_location_t],
+      insns_info: [704, self.iseq_insn_info],
+      local_table: [832, CType::Pointer.new { self.ID }],
+      catch_table: [864, CType::Pointer.new { self.iseq_catch_table }],
+      parent_iseq: [896, CType::Pointer.new { self.rb_iseq_struct }],
+      local_iseq: [928, CType::Pointer.new { self.rb_iseq_struct }],
+      is_entries: [960, CType::Pointer.new { self.iseq_inline_storage_entry }],
+      call_data: [992, CType::Pointer.new { self.rb_call_data }],
+      variable: [1024, CType::Struct.new(
+        "", 20,
+        flip_count: [0, self.rb_snum_t],
+        script_lines: [32, self.VALUE],
+        coverage: [64, self.VALUE],
+        pc2branchindex: [96, self.VALUE],
+        original_iseq: [128, CType::Pointer.new { self.VALUE }],
+      )],
+      local_table_size: [1184, CType::Immediate.new(-4)],
+      ic_size: [1216, CType::Immediate.new(-4)],
+      ise_size: [1248, CType::Immediate.new(-4)],
+      ivc_size: [1280, CType::Immediate.new(-4)],
+      icvarc_size: [1312, CType::Immediate.new(-4)],
+      ci_size: [1344, CType::Immediate.new(-4)],
+      stack_max: [1376, CType::Immediate.new(-4)],
+      mark_bits: [1408, CType::Union.new(
+        "", 4,
+        list: CType::Pointer.new { self.iseq_bits_t },
+        single: self.iseq_bits_t,
+      )],
+      catch_except_p: [1440, self._Bool],
+      builtin_inline_p: [1448, self._Bool],
+      outer_variables: [1472, CType::Pointer.new { self.rb_id_table }],
+      mandatory_only_iseq: [1504, CType::Pointer.new { self.rb_iseq_t }],
+      jit_func: [1536, CType::Immediate.new(1)],
+      total_calls: [1568, CType::Immediate.new(-5)],
+      jit_unit: [1600, CType::Pointer.new { self.rb_mjit_unit }],
+    )
+  end
+
+  def C.rb_iseq_location_t
+    @rb_iseq_location_t ||= CType::Struct.new(
+      "rb_iseq_location_struct", 36,
+      pathobj: [0, self.VALUE, true],
+      base_label: [32, self.VALUE, true],
+      label: [64, self.VALUE, true],
+      first_lineno: [96, self.VALUE, true],
+      node_id: [128, CType::Immediate.new(4)],
+      code_location: [160, self.rb_code_location_t],
+    )
+  end
+
+  def C.rb_iseq_struct
+    @rb_iseq_struct ||= CType::Struct.new(
+      "rb_iseq_struct", 20,
+      flags: [0, self.VALUE],
+      wrapper: [32, self.VALUE],
+      body: [64, CType::Pointer.new { self.rb_iseq_constant_body }],
+      aux: [96, CType::Union.new(
+        "", 8,
+        compile_data: CType::Pointer.new { self.iseq_compile_data },
+        loader: CType::Struct.new(
+          "", 8,
+          obj: [0, self.VALUE],
+          index: [32, CType::Immediate.new(4)],
+        ),
+        exec: CType::Struct.new(
+          "", 8,
+          local_hooks: [0, CType::Pointer.new { self.rb_hook_list_struct }],
+          global_trace_events: [32, self.rb_event_flag_t],
+        ),
+      )],
+    )
+  end
+
+  def C.rb_iseq_t
+    @rb_iseq_t ||= self.rb_iseq_struct
+  end
+
+  def C.rb_iv_index_tbl_entry
+    @rb_iv_index_tbl_entry ||= CType::Struct.new(
+      "rb_iv_index_tbl_entry", 16,
+      index: [0, CType::Immediate.new(-4)],
+      class_serial: [32, self.rb_serial_t],
+      class_value: [96, self.VALUE],
+    )
+  end
+
+  def C.rb_method_definition_struct
+    @rb_method_definition_struct ||= CType::Struct.new(
+      "rb_method_definition_struct", 28,
+      type: [0, self.rb_method_type_t],
+      iseq_overload: [4, CType::BitField.new(1, 4)],
+      alias_count: [5, CType::BitField.new(27, 5)],
+      complemented_count: [32, CType::BitField.new(28, 0)],
+      no_redef_warning: [60, CType::BitField.new(1, 4)],
+      body: [64, CType::Union.new(
+        "", 12,
+        iseq: self.rb_method_iseq_t,
+        cfunc: self.rb_method_cfunc_t,
+        attr: self.rb_method_attr_t,
+        alias: self.rb_method_alias_t,
+        refined: self.rb_method_refined_t,
+        bmethod: self.rb_method_bmethod_t,
+        optimized: self.rb_method_optimized_t,
+      )],
+      original_id: [160, self.ID],
+      method_serial: [192, CType::Immediate.new(-4)],
+    )
+  end
+
+  def C.rb_method_iseq_t
+    @rb_method_iseq_t ||= CType::Struct.new(
+      "rb_method_iseq_struct", 8,
+      iseqptr: [0, CType::Pointer.new { self.rb_iseq_t }],
+      cref: [32, CType::Pointer.new { self.rb_cref_t }],
+    )
+  end
+
+  def C.rb_method_type_t
+    @rb_method_type_t ||= CType::Immediate.new(4)
+  end
+
+  def C.rb_mjit_compile_info
+    @rb_mjit_compile_info ||= CType::Struct.new(
+      "rb_mjit_compile_info", 5,
+      disable_ivar_cache: [0, self._Bool],
+      disable_exivar_cache: [8, self._Bool],
+      disable_send_cache: [16, self._Bool],
+      disable_inlining: [24, self._Bool],
+      disable_const_cache: [32, self._Bool],
+    )
+  end
+
+  def C.rb_mjit_unit
+    @rb_mjit_unit ||= CType::Struct.new(
+      "rb_mjit_unit", 36,
+      unode: [0, self.ccan_list_node],
+      id: [64, CType::Immediate.new(4)],
+      handle: [96, CType::Pointer.new { CType::Immediate.new(0) }],
+      iseq: [128, CType::Pointer.new { self.rb_iseq_t }],
+      used_code_p: [160, self._Bool],
+      compact_p: [168, self._Bool],
+      compile_info: [176, self.rb_mjit_compile_info],
+      cc_entries: [224, CType::Pointer.new { CType::Pointer.new { self.rb_callcache } }],
+      cc_entries_size: [256, CType::Immediate.new(-4)],
+    )
+  end
+
+  def C.rb_serial_t
+    @rb_serial_t ||= CType::Immediate.new(-6)
+  end
+
+  def C._Bool = CType::Bool.new
+
+  def C.ID = CType::Stub.new(:ID)
+
+  def C.rb_thread_struct = CType::Stub.new(:rb_thread_struct)
+
+  def C.vm_call_handler = CType::Stub.new(:vm_call_handler)
+
+  def C.method_missing_reason = CType::Stub.new(:method_missing_reason)
+
+  def C.rb_callinfo_kwarg = CType::Stub.new(:rb_callinfo_kwarg)
+
+  def C.rb_cref_struct = CType::Stub.new(:rb_cref_struct)
+
+  def C.rb_scope_visibility_t = CType::Stub.new(:rb_scope_visibility_t)
+
+  def C.rb_iseq_type = CType::Stub.new(:rb_iseq_type)
+
+  def C.rb_iseq_param_keyword = CType::Stub.new(:rb_iseq_param_keyword)
+
+  def C.iseq_insn_info = CType::Stub.new(:iseq_insn_info)
+
+  def C.iseq_catch_table = CType::Stub.new(:iseq_catch_table)
+
+  def C.rb_snum_t = CType::Stub.new(:rb_snum_t)
+
+  def C.iseq_bits_t = CType::Stub.new(:iseq_bits_t)
+
+  def C.rb_id_table = CType::Stub.new(:rb_id_table)
+
+  def C.rb_code_location_t = CType::Stub.new(:rb_code_location_t)
+
+  def C.iseq_compile_data = CType::Stub.new(:iseq_compile_data)
+
+  def C.rb_hook_list_struct = CType::Stub.new(:rb_hook_list_struct)
+
+  def C.rb_event_flag_t = CType::Stub.new(:rb_event_flag_t)
+
+  def C.rb_method_cfunc_t = CType::Stub.new(:rb_method_cfunc_t)
+
+  def C.rb_method_attr_t = CType::Stub.new(:rb_method_attr_t)
+
+  def C.rb_method_alias_t = CType::Stub.new(:rb_method_alias_t)
+
+  def C.rb_method_refined_t = CType::Stub.new(:rb_method_refined_t)
+
+  def C.rb_method_bmethod_t = CType::Stub.new(:rb_method_bmethod_t)
+
+  def C.rb_method_optimized_t = CType::Stub.new(:rb_method_optimized_t)
+
+  def C.ccan_list_node = CType::Stub.new(:ccan_list_node)
+end
diff --git a/lib/mjit/c_64.rb b/lib/mjit/c_64.rb
new file mode 100644
index 0000000000..cd0fd47e9e
--- /dev/null
+++ b/lib/mjit/c_64.rb
@@ -0,0 +1,437 @@
+require_relative 'c_type'
+
+module RubyVM::MJIT
+  C = Object.new
+
+  def C.NOT_COMPILED_STACK_SIZE = - 1
+
+  def C.USE_LAZY_LOAD = false
+
+  def C.USE_RVARGC = true
+
+  def C.VM_CALL_KW_SPLAT = ( 0x01 << self.VM_CALL_KW_SPLAT_bit )
+
+  def C.VM_CALL_TAILCALL = ( 0x01 << self.VM_CALL_TAILCALL_bit )
+
+  def C.VM_METHOD_TYPE_CFUNC = 1
+
+  def C.VM_METHOD_TYPE_ISEQ = 0
+
+  def C.VM_CALL_KW_SPLAT_bit = 7
+
+  def C.VM_CALL_TAILCALL_bit = 8
+
+  def C.CALL_DATA
+    @CALL_DATA ||= self.rb_call_data
+  end
+
+  def C.IC
+    @IC ||= self.iseq_inline_constant_cache
+  end
+
+  def C.IVC
+    @IVC ||= self.iseq_inline_iv_cache_entry
+  end
+
+  def C.RB_BUILTIN
+    @RB_BUILTIN ||= self.rb_builtin_function
+  end
+
+  def C.VALUE
+    @VALUE ||= CType::Immediate.new(-5)
+  end
+
+  def C.compile_branch
+    @compile_branch ||= CType::Struct.new(
+      "compile_branch", 8,
+      stack_size: [0, CType::Immediate.new(-4)],
+      finish_p: [32, self._Bool],
+    )
+  end
+
+  def C.compile_status
+    @compile_status ||= CType::Struct.new(
+      "compile_status", 120,
+      success: [0, self._Bool],
+      stack_size_for_pos: [64, CType::Pointer.new { CType::Immediate.new(4) }],
+      local_stack_p: [128, self._Bool],
+      is_entries: [192, CType::Pointer.new { self.iseq_inline_storage_entry }],
+      cc_entries_index: [256, CType::Immediate.new(4)],
+      compiled_iseq: [320, CType::Pointer.new { self.rb_iseq_constant_body }],
+      compiled_id: [384, CType::Immediate.new(4)],
+      compile_info: [448, CType::Pointer.new { self.rb_mjit_compile_info }],
+      merge_ivar_guards_p: [512, self._Bool],
+      ivar_serial: [576, self.rb_serial_t],
+      max_ivar_index: [640, CType::Immediate.new(-5)],
+      inlined_iseqs: [704, CType::Pointer.new { CType::Pointer.new { self.rb_iseq_constant_body } }],
+      inline_context: [768, self.inlined_call_context],
+    )
+  end
+
+  def C.inlined_call_context
+    @inlined_call_context ||= CType::Struct.new(
+      "inlined_call_context", 24,
+      orig_argc: [0, CType::Immediate.new(4)],
+      me: [64, self.VALUE],
+      param_size: [128, CType::Immediate.new(4)],
+      local_size: [160, CType::Immediate.new(4)],
+    )
+  end
+
+  def C.iseq_inline_constant_cache
+    @iseq_inline_constant_cache ||= CType::Struct.new(
+      "iseq_inline_constant_cache", 16,
+      entry: [0, CType::Pointer.new { self.iseq_inline_constant_cache_entry }],
+      segments: [64, CType::Pointer.new { self.ID }],
+    )
+  end
+
+  def C.iseq_inline_constant_cache_entry
+    @iseq_inline_constant_cache_entry ||= CType::Struct.new(
+      "iseq_inline_constant_cache_entry", 40,
+      flags: [0, self.VALUE],
+      value: [64, self.VALUE],
+      _unused1: [128, self.VALUE],
+      _unused2: [192, self.VALUE],
+      ic_cref: [256, CType::Pointer.new { self.rb_cref_t }],
+    )
+  end
+
+  def C.iseq_inline_iv_cache_entry
+    @iseq_inline_iv_cache_entry ||= CType::Struct.new(
+      "iseq_inline_iv_cache_entry", 8,
+      entry: [0, CType::Pointer.new { self.rb_iv_index_tbl_entry }],
+    )
+  end
+
+  def C.iseq_inline_storage_entry
+    @iseq_inline_storage_entry ||= CType::Union.new(
+      "iseq_inline_storage_entry", 16,
+      once: CType::Struct.new(
+        "", 16,
+        running_thread: [0, CType::Pointer.new { self.rb_thread_struct }],
+        value: [64, self.VALUE],
+      ),
+      ic_cache: self.iseq_inline_constant_cache,
+      iv_cache: self.iseq_inline_iv_cache_entry,
+    )
+  end
+
+  def C.mjit_options
+    @mjit_options ||= CType::Struct.new(
+      "mjit_options", 32,
+      on: [0, self._Bool],
+      save_temps: [8, self._Bool],
+      warnings: [16, self._Bool],
+      debug: [24, self._Bool],
+      debug_flags: [64, CType::Pointer.new { CType::Immediate.new(2) }],
+      wait: [128, self._Bool],
+      min_calls: [160, CType::Immediate.new(-4)],
+      verbose: [192, CType::Immediate.new(4)],
+      max_cache_size: [224, CType::Immediate.new(4)],
+    )
+  end
+
+  def C.rb_builtin_function
+    @rb_builtin_function ||= CType::Struct.new(
+      "rb_builtin_function", 32,
+      func_ptr: [0, CType::Pointer.new { CType::Immediate.new(0) }],
+      argc: [64, CType::Immediate.new(4)],
+      index: [96, CType::Immediate.new(4)],
+      name: [128, CType::Pointer.new { CType::Immediate.new(2) }],
+      compiler: [192, CType::Immediate.new(1)],
+    )
+  end
+
+  def C.rb_call_data
+    @rb_call_data ||= CType::Struct.new(
+      "rb_call_data", 16,
+      ci: [0, CType::Pointer.new { self.rb_callinfo }],
+      cc: [64, CType::Pointer.new { self.rb_callcache }],
+    )
+  end
+
+  def C.rb_callable_method_entry_struct
+    @rb_callable_method_entry_struct ||= CType::Struct.new(
+      "rb_callable_method_entry_struct", 40,
+      flags: [0, self.VALUE],
+      defined_class: [64, self.VALUE],
+      def: [128, CType::Pointer.new { self.rb_method_definition_struct }],
+      called_id: [192, self.ID],
+      owner: [256, self.VALUE],
+    )
+  end
+
+  def C.rb_callcache
+    @rb_callcache ||= CType::Struct.new(
+      "rb_callcache", 40,
+      flags: [0, self.VALUE],
+      klass: [64, self.VALUE],
+      cme_: [128, CType::Pointer.new { self.rb_callable_method_entry_struct }],
+      call_: [192, self.vm_call_handler],
+      aux_: [256, CType::Union.new(
+        "", 8,
+        attr_index: CType::Immediate.new(-4),
+        method_missing_reason: self.method_missing_reason,
+        v: self.VALUE,
+      )],
+    )
+  end
+
+  def C.rb_callinfo
+    @rb_callinfo ||= CType::Struct.new(
+      "rb_callinfo", 40,
+      flags: [0, self.VALUE],
+      kwarg: [64, CType::Pointer.new { self.rb_callinfo_kwarg }],
+      mid: [128, self.VALUE],
+      flag: [192, self.VALUE],
+      argc: [256, self.VALUE],
+    )
+  end
+
+  def C.rb_cref_t
+    @rb_cref_t ||= CType::Struct.new(
+      "rb_cref_struct", 40,
+      flags: [0, self.VALUE],
+      refinements: [64, self.VALUE],
+      klass_or_self: [128, self.VALUE],
+      next: [192, CType::Pointer.new { self.rb_cref_struct }],
+      scope_visi: [256, self.rb_scope_visibility_t],
+    )
+  end
+
+  def C.rb_iseq_constant_body
+    @rb_iseq_constant_body ||= CType::Struct.new(
+      "rb_iseq_constant_body", 336,
+      type: [0, self.rb_iseq_type],
+      iseq_size: [32, CType::Immediate.new(-4)],
+      iseq_encoded: [64, CType::Pointer.new { self.VALUE }],
+      param: [128, CType::Struct.new(
+        "", 48,
+        flags: [0, CType::Struct.new(
+          "", 4,
+          has_lead: [0, CType::BitField.new(1, 0)],
+          has_opt: [1, CType::BitField.new(1, 1)],
+          has_rest: [2, CType::BitField.new(1, 2)],
+          has_post: [3, CType::BitField.new(1, 3)],
+          has_kw: [4, CType::BitField.new(1, 4)],
+          has_kwrest: [5, CType::BitField.new(1, 5)],
+          has_block: [6, CType::BitField.new(1, 6)],
+          ambiguous_param0: [7, CType::BitField.new(1, 7)],
+          accepts_no_kwarg: [8, CType::BitField.new(1, 0)],
+          ruby2_keywords: [9, CType::BitField.new(1, 1)],
+        )],
+        size: [32, CType::Immediate.new(-4)],
+        lead_num: [64, CType::Immediate.new(4)],
+        opt_num: [96, CType::Immediate.new(4)],
+        rest_start: [128, CType::Immediate.new(4)],
+        post_start: [160, CType::Immediate.new(4)],
+        post_num: [192, CType::Immediate.new(4)],
+        block_start: [224, CType::Immediate.new(4)],
+        opt_table: [256, CType::Pointer.new { self.VALUE }],
+        keyword: [320, CType::Pointer.new { self.rb_iseq_param_keyword }],
+      )],
+      location: [512, self.rb_iseq_location_t],
+      insns_info: [960, self.iseq_insn_info],
+      local_table: [1216, CType::Pointer.new { self.ID }],
+      catch_table: [1280, CType::Pointer.new { self.iseq_catch_table }],
+      parent_iseq: [1344, CType::Pointer.new { self.rb_iseq_struct }],
+      local_iseq: [1408, CType::Pointer.new { self.rb_iseq_struct }],
+      is_entries: [1472, CType::Pointer.new { self.iseq_inline_storage_entry }],
+      call_data: [1536, CType::Pointer.new { self.rb_call_data }],
+      variable: [1600, CType::Struct.new(
+        "", 40,
+        flip_count: [0, self.rb_snum_t],
+        script_lines: [64, self.VALUE],
+        coverage: [128, self.VALUE],
+        pc2branchindex: [192, self.VALUE],
+        original_iseq: [256, CType::Pointer.new { self.VALUE }],
+      )],
+      local_table_size: [1920, CType::Immediate.new(-4)],
+      ic_size: [1952, CType::Immediate.new(-4)],
+      ise_size: [1984, CType::Immediate.new(-4)],
+      ivc_size: [2016, CType::Immediate.new(-4)],
+      icvarc_size: [2048, CType::Immediate.new(-4)],
+      ci_size: [2080, CType::Immediate.new(-4)],
+      stack_max: [2112, CType::Immediate.new(-4)],
+      mark_bits: [2176, CType::Union.new(
+        "", 8,
+        list: CType::Pointer.new { self.iseq_bits_t },
+        single: self.iseq_bits_t,
+      )],
+      catch_except_p: [2240, self._Bool],
+      builtin_inline_p: [2248, self._Bool],
+      outer_variables: [2304, CType::Pointer.new { self.rb_id_table }],
+      mandatory_only_iseq: [2368, CType::Pointer.new { self.rb_iseq_t }],
+      jit_func: [2432, CType::Immediate.new(1)],
+      total_calls: [2496, CType::Immediate.new(-5)],
+      jit_unit: [2560, CType::Pointer.new { self.rb_mjit_unit }],
+      yjit_payload: [2624, CType::Pointer.new { CType::Immediate.new(0) }],
+    )
+  end
+
+  def C.rb_iseq_location_t
+    @rb_iseq_location_t ||= CType::Struct.new(
+      "rb_iseq_location_struct", 56,
+      pathobj: [0, self.VALUE, true],
+      base_label: [64, self.VALUE, true],
+      label: [128, self.VALUE, true],
+      first_lineno: [192, self.VALUE, true],
+      node_id: [256, CType::Immediate.new(4)],
+      code_location: [288, self.rb_code_location_t],
+    )
+  end
+
+  def C.rb_iseq_struct
+    @rb_iseq_struct ||= CType::Struct.new(
+      "rb_iseq_struct", 40,
+      flags: [0, self.VALUE],
+      wrapper: [64, self.VALUE],
+      body: [128, CType::Pointer.new { self.rb_iseq_constant_body }],
+      aux: [192, CType::Union.new(
+        "", 16,
+        compile_data: CType::Pointer.new { self.iseq_compile_data },
+        loader: CType::Struct.new(
+          "", 16,
+          obj: [0, self.VALUE],
+          index: [64, CType::Immediate.new(4)],
+        ),
+        exec: CType::Struct.new(
+          "", 16,
+          local_hooks: [0, CType::Pointer.new { self.rb_hook_list_struct }],
+          global_trace_events: [64, self.rb_event_flag_t],
+        ),
+      )],
+    )
+  end
+
+  def C.rb_iseq_t
+    @rb_iseq_t ||= self.rb_iseq_struct
+  end
+
+  def C.rb_iv_index_tbl_entry
+    @rb_iv_index_tbl_entry ||= CType::Struct.new(
+      "rb_iv_index_tbl_entry", 24,
+      index: [0, CType::Immediate.new(-4)],
+      class_serial: [64, self.rb_serial_t],
+      class_value: [128, self.VALUE],
+    )
+  end
+
+  def C.rb_method_definition_struct
+    @rb_method_definition_struct ||= CType::Struct.new(
+      "rb_method_definition_struct", 48,
+      type: [0, self.rb_method_type_t],
+      iseq_overload: [4, CType::BitField.new(1, 4)],
+      alias_count: [5, CType::BitField.new(27, 5)],
+      complemented_count: [32, CType::BitField.new(28, 0)],
+      no_redef_warning: [60, CType::BitField.new(1, 4)],
+      body: [64, CType::Union.new(
+        "", 24,
+        iseq: self.rb_method_iseq_t,
+        cfunc: self.rb_method_cfunc_t,
+        attr: self.rb_method_attr_t,
+        alias: self.rb_method_alias_t,
+        refined: self.rb_method_refined_t,
+        bmethod: self.rb_method_bmethod_t,
+        optimized: self.rb_method_optimized_t,
+      )],
+      original_id: [256, self.ID],
+      method_serial: [320, CType::Immediate.new(-5)],
+    )
+  end
+
+  def C.rb_method_iseq_t
+    @rb_method_iseq_t ||= CType::Struct.new(
+      "rb_method_iseq_struct", 16,
+      iseqptr: [0, CType::Pointer.new { self.rb_iseq_t }],
+      cref: [64, CType::Pointer.new { self.rb_cref_t }],
+    )
+  end
+
+  def C.rb_method_type_t
+    @rb_method_type_t ||= CType::Immediate.new(4)
+  end
+
+  def C.rb_mjit_compile_info
+    @rb_mjit_compile_info ||= CType::Struct.new(
+      "rb_mjit_compile_info", 5,
+      disable_ivar_cache: [0, self._Bool],
+      disable_exivar_cache: [8, self._Bool],
+      disable_send_cache: [16, self._Bool],
+      disable_inlining: [24, self._Bool],
+      disable_const_cache: [32, self._Bool],
+    )
+  end
+
+  def C.rb_mjit_unit
+    @rb_mjit_unit ||= CType::Struct.new(
+      "rb_mjit_unit", 64,
+      unode: [0, self.ccan_list_node],
+      id: [128, CType::Immediate.new(4)],
+      handle: [192, CType::Pointer.new { CType::Immediate.new(0) }],
+      iseq: [256, CType::Pointer.new { self.rb_iseq_t }],
+      used_code_p: [320, self._Bool],
+      compact_p: [328, self._Bool],
+      compile_info: [336, self.rb_mjit_compile_info],
+      cc_entries: [384, CType::Pointer.new { CType::Pointer.new { self.rb_callcache } }],
+      cc_entries_size: [448, CType::Immediate.new(-4)],
+    )
+  end
+
+  def C.rb_serial_t
+    @rb_serial_t ||= CType::Immediate.new(-6)
+  end
+
+  def C._Bool = CType::Bool.new
+
+  def C.ID = CType::Stub.new(:ID)
+
+  def C.rb_thread_struct = CType::Stub.new(:rb_thread_struct)
+
+  def C.vm_call_handler = CType::Stub.new(:vm_call_handler)
+
+  def C.method_missing_reason = CType::Stub.new(:method_missing_reason)
+
+  def C.rb_callinfo_kwarg = CType::Stub.new(:rb_callinfo_kwarg)
+
+  def C.rb_cref_struct = CType::Stub.new(:rb_cref_struct)
+
+  def C.rb_scope_visibility_t = CType::Stub.new(:rb_scope_visibility_t)
+
+  def C.rb_iseq_type = CType::Stub.new(:rb_iseq_type)
+
+  def C.rb_iseq_param_keyword = CType::Stub.new(:rb_iseq_param_keyword)
+
+  def C.iseq_insn_info = CType::Stub.new(:iseq_insn_info)
+
+  def C.iseq_catch_table = CType::Stub.new(:iseq_catch_table)
+
+  def C.rb_snum_t = CType::Stub.new(:rb_snum_t)
+
+  def C.iseq_bits_t = CType::Stub.new(:iseq_bits_t)
+
+  def C.rb_id_table = CType::Stub.new(:rb_id_table)
+
+  def C.rb_code_location_t = CType::Stub.new(:rb_code_location_t)
+
+  def C.iseq_compile_data = CType::Stub.new(:iseq_compile_data)
+
+  def C.rb_hook_list_struct = CType::Stub.new(:rb_hook_list_struct)
+
+  def C.rb_event_flag_t = CType::Stub.new(:rb_event_flag_t)
+
+  def C.rb_method_cfunc_t = CType::Stub.new(:rb_method_cfunc_t)
+
+  def C.rb_method_attr_t = CType::Stub.new(:rb_method_attr_t)
+
+  def C.rb_method_alias_t = CType::Stub.new(:rb_method_alias_t)
+
+  def C.rb_method_refined_t = CType::Stub.new(:rb_method_refined_t)
+
+  def C.rb_method_bmethod_t = CType::Stub.new(:rb_method_bmethod_t)
+
+  def C.rb_method_optimized_t = CType::Stub.new(:rb_method_optimized_t)
+
+  def C.ccan_list_node = CType::Stub.new(:ccan_list_node)
+end
diff --git a/lib/mjit/c_pointer.rb b/lib/mjit/c_pointer.rb
new file mode 100644
index 0000000000..75ed8babd5
--- /dev/null
+++ b/lib/mjit/c_pointer.rb
@@ -0,0 +1,333 @@
+module RubyVM::MJIT
+  # Every class under this namespace is a pointer. Even if the type is
+  # immediate, it shouldn't be dereferenced until `*` is called.
+  module CPointer
+    # Patched PACK_MAP to support unsigned operations
+    PACK_MAP = Fiddle::PackInfo::PACK_MAP.dup
+    PACK_MAP.keys.each do |type|
+      if type.negative? || type == Fiddle::TYPE_VOIDP
+        PACK_MAP[type] = PACK_MAP[type].upcase
+      end
+    end
+
+    # Note: We'd like to avoid alphabetic method names to avoid a conflict
+    # with member methods. to_i and to_s are considered an exception.
+    class Struct
+      # @param name [String]
+      # @param sizeof [Integer]
+      # @param members [Hash{ Symbol => [Integer, RubyVM::MJIT::CType::*] }]
+      def initialize(addr, sizeof, members)
+        @addr = addr
+        @sizeof = sizeof
+        @members = members
+      end
+
+      # Get a raw address
+      def to_i
+        @addr
+      end
+
+      # Serialized address for generated code
+      def to_s
+        "0x#{@addr.to_s(16)}"
+      end
+
+      # Pointer diff
+      def -(struct)
+        raise ArgumentError if self.class != struct.class
+        (@addr - struct.to_i) / @sizeof
+      end
+
+      # Primitive API that does no automatic dereference
+      # TODO: remove this?
+      # @param member [Symbol]
+      def [](member)
+        offset, type = @members.fetch(member)
+        type.new(@addr + offset / 8)
+      end
+
+      private
+
+      # @param member [Symbol]
+      # @param value [Object]
+      def []=(member, value)
+        offset, type = @members.fetch(member)
+        type[@addr + offset / 8] = value
+      end
+
+      # @param sizeof [Integer]
+      # @param members [Hash{ Symbol => [Integer, RubyVM::MJIT::CType::*] }]
+      def self.define(sizeof, members)
+        Class.new(self) do
+          # Return the size of this type
+          define_singleton_method(:sizeof) { sizeof }
+
+          define_method(:initialize) do |addr = nil|
+            if addr.nil? # TODO: get rid of this feature later
+              addr = Fiddle.malloc(sizeof)
+            end
+            super(addr, sizeof, members)
+          end
+
+          members.each do |member, (offset, type, to_ruby)|
+            # Intelligent API that does automatic dereference
+            define_method(member) do
+              value = self[member]
+              if value.respond_to?(:*)
+                value = value.*
+              end
+              if to_ruby
+                value = C.to_ruby(value)
+              end
+              value
+            end
+
+            define_method("#{member}=") do |value|
+              self[member] = value
+            end
+          end
+        end
+      end
+    end
+
+    # Note: We'd like to avoid alphabetic method names to avoid a conflict
+    # with member methods. to_i is considered an exception.
+    class Union
+      # @param _name [String] To be used when it starts defining a union pointer class
+      # @param sizeof [Integer]
+      # @param members [Hash{ Symbol => RubyVM::MJIT::CType::* }]
+      def initialize(addr, sizeof, members)
+        @addr = addr
+        @sizeof = sizeof
+        @members = members
+      end
+
+      # Get a raw address
+      def to_i
+        @addr
+      end
+
+      # Move addr to access this pointer like an array
+      def +(index)
+        raise ArgumentError unless index.is_a?(Integer)
+        self.class.new(@addr + index * @sizeof)
+      end
+
+      # Pointer diff
+      def -(union)
+        raise ArgumentError if self.class != union.class
+        (@addr - union.instance_variable_get(:@addr)) / @sizeof
+      end
+
+      # @param sizeof [Integer]
+      # @param members [Hash{ Symbol => RubyVM::MJIT::CType::* }]
+      def self.define(sizeof, members)
+        Class.new(self) do
+          # Return the size of this type
+          define_singleton_method(:sizeof) { sizeof }
+
+          define_method(:initialize) do |addr|
+            super(addr, sizeof, members)
+          end
+
+          members.each do |member, type|
+            # Intelligent API that does automatic dereference
+            define_method(member) do
+              value = type.new(@addr)
+              if value.respond_to?(:*)
+                value = value.*
+              end
+              value
+            end
+          end
+        end
+      end
+    end
+
+    class Immediate
+      # @param addr [Integer]
+      # @param size [Integer]
+      # @param pack [String]
+      def initialize(addr, size, pack)
+        @addr = addr
+        @size = size
+        @pack = pack
+      end
+
+      # Get a raw address
+      def to_i
+        @addr
+      end
+
+      # Move addr to addess this pointer like an array
+      def +(index)
+        Immediate.new(@addr + index * @size, @size, @pack)
+      end
+
+      # Dereference
+      def *
+        self[0]
+      end
+
+      # Array access
+      def [](index)
+        return nil if @addr == 0
+        Fiddle::Pointer.new(@addr + index * @size)[0, @size].unpack1(@pack)
+      end
+
+      # Array set
+      def []=(index, value)
+        Fiddle::Pointer.new(@addr + index * @size)[0, @size] = [value].pack(@pack)
+      end
+
+      # Serialized address for generated code. Used for embedding things like body->iseq_encoded.
+      def to_s
+        "0x#{Integer(@addr).to_s(16)}"
+      end
+
+      # @param fiddle_type [Integer] Fiddle::TYPE_*
+      def self.define(fiddle_type)
+        size = Fiddle::PackInfo::SIZE_MAP.fetch(fiddle_type)
+        pack = PACK_MAP.fetch(fiddle_type)
+
+        Class.new(self) do
+          define_method(:initialize) do |addr|
+            super(addr, size, pack)
+          end
+
+          define_singleton_method(:size) do
+            size
+          end
+
+          # Type-level []=: Used by struct fields
+          define_singleton_method(:[]=) do |addr, value|
+            Fiddle::Pointer.new(addr)[0, size] = [value].pack(pack)
+          end
+        end
+      end
+    end
+
+    # -Fiddle::TYPE_CHAR Immediate with special handling of true/false
+    class Bool < Immediate.define(-Fiddle::TYPE_CHAR)
+      # Dereference
+      def *
+        return nil if @addr == 0
+        super != 0
+      end
+
+      def self.[]=(addr, value)
+        super(addr, value ? 1 : 0)
+      end
+    end
+
+    class Pointer
+      attr_reader :type
+
+      # @param addr [Integer]
+      # @param type [Class] RubyVM::MJIT::CType::*
+      def initialize(addr, type)
+        @addr = addr
+        @type = type
+      end
+
+      # Move addr to addess this pointer like an array
+      def +(index)
+        raise ArgumentError unless index.is_a?(Integer)
+        Pointer.new(@addr + index * Fiddle::SIZEOF_VOIDP, @type)
+      end
+
+      # Dereference
+      def *
+        return nil if dest_addr == 0
+        @type.new(dest_addr)
+      end
+
+      # Array access
+      def [](index)
+        (self + index).*
+      end
+
+      # Array set
+      # @param index [Integer]
+      # @param value [Integer, RubyVM::MJIT::CPointer::Struct] an address itself or an object that return an address with to_i
+      def []=(index, value)
+        Fiddle::Pointer.new(@addr + index * Fiddle::SIZEOF_VOIDP)[0, Fiddle::SIZEOF_VOIDP] =
+          [value.to_i].pack(PACK_MAP[Fiddle::TYPE_VOIDP])
+      end
+
+      private
+
+      def dest_addr
+        Fiddle::Pointer.new(@addr)[0, Fiddle::SIZEOF_VOIDP].unpack1(PACK_MAP[Fiddle::TYPE_VOIDP])
+      end
+
+      def self.define(block)
+        Class.new(self) do
+          define_method(:initialize) do |addr|
+            super(addr, block.call)
+          end
+
+          # Type-level []=: Used by struct fields
+          # @param addr [Integer]
+          # @param value [Integer, RubyVM::MJIT::CPointer::Struct] an address itself, or an object that return an address with to_i
+          define_singleton_method(:[]=) do |addr, value|
+            value = value.to_i
+            Fiddle::Pointer.new(addr)[0, Fiddle::SIZEOF_VOIDP] = [value].pack(PACK_MAP[Fiddle::TYPE_VOIDP])
+          end
+        end
+      end
+    end
+
+    class BitField
+      # @param addr [Integer]
+      # @param width [Integer]
+      # @param offset [Integer]
+      def initialize(addr, width, offset)
+        @addr = addr
+        @width = width
+        @offset = offset
+      end
+
+      # Dereference
+      def *
+        if @width != 1
+          raise NotImplementedError.new("Non-1 width is not implemented yet")
+        end
+        byte = Fiddle::Pointer.new(@addr)[0, Fiddle::SIZEOF_CHAR].unpack('c').first
+        bit = 1 & (byte >> @offset)
+        bit == 1
+      end
+
+      # @param width [Integer]
+      # @param offset [Integer]
+      def self.define(width, offset)
+        Class.new(self) do
+          define_method(:initialize) do |addr|
+            super(addr, width, offset)
+          end
+        end
+      end
+    end
+
+    # Give a name to a dynamic CPointer class to see it on inspect
+    def self.with_class_name(prefix, name, cache: false, &block)
+      return block.call if name.empty?
+
+      # Use a cached result only if cache: true
+      class_name = "#{prefix}_#{name}"
+      klass =
+        if cache && self.const_defined?(class_name)
+          self.const_get(class_name)
+        else
+          block.call
+        end
+
+      # Give it a name unless it's already defined
+      unless self.const_defined?(class_name)
+        self.const_set(class_name, klass)
+      end
+
+      klass
+    end
+  end
+end
diff --git a/lib/mjit/c_type.rb b/lib/mjit/c_type.rb
new file mode 100644
index 0000000000..be93b36e90
--- /dev/null
+++ b/lib/mjit/c_type.rb
@@ -0,0 +1,77 @@
+require 'fiddle'
+require 'fiddle/pack'
+require_relative 'c_pointer'
+
+module RubyVM::MJIT
+  module CType
+    module Struct
+      # @param name [String]
+      # @param members [Hash{ Symbol => [Integer, RubyVM::MJIT::CType::*] }]
+      def self.new(name, sizeof, **members)
+        name = members.keys.join('_') if name.empty?
+        CPointer.with_class_name('Struct', name) do
+          CPointer::Struct.define(sizeof, members)
+        end
+      end
+    end
+
+    module Union
+      # @param name [String]
+      # @param members [Hash{ Symbol => RubyVM::MJIT::CType::* }]
+      def self.new(name, sizeof, **members)
+        name = members.keys.join('_') if name.empty?
+        CPointer.with_class_name('Union', name) do
+          CPointer::Union.define(sizeof, members)
+        end
+      end
+    end
+
+    module Immediate
+      # @param fiddle_type [Integer] Fiddle::TYPE_*
+      def self.new(fiddle_type)
+        name = Fiddle.constants.find do |const|
+          const.start_with?('TYPE_') && Fiddle.const_get(const) == fiddle_type.abs
+        end&.to_s
+        name.delete_prefix!('TYPE_')
+        if fiddle_type.negative?
+          name.prepend('U')
+        end
+        CPointer.with_class_name('Immediate', name, cache: true) do
+          CPointer::Immediate.define(fiddle_type)
+        end
+      end
+    end
+
+    module Bool
+      def self.new
+        CPointer::Bool
+      end
+    end
+
+    class Pointer
+      # This takes a block to avoid "stack level too deep" on a cyclic reference
+      # @param block [Proc]
+      def self.new(&block)
+        CPointer.with_class_name('Pointer', block.object_id.to_s) do
+          CPointer::Pointer.define(block)
+        end
+      end
+    end
+
+    module BitField
+      # @param width [Integer]
+      # @param offset [Integer]
+      def self.new(width, offset)
+        CPointer.with_class_name('BitField', "#{offset}_#{width}") do
+          CPointer::BitField.define(width, offset)
+        end
+      end
+    end
+
+    # Types that are referenced but not part of code generation targets
+    Stub = ::Struct.new(:name)
+
+    # Types that it failed to figure out from the header
+    Unknown = Module.new
+  end
+end
diff --git a/lib/mjit/compiler.rb b/lib/mjit/compiler.rb
new file mode 100644
index 0000000000..254ecc885f
--- /dev/null
+++ b/lib/mjit/compiler.rb
@@ -0,0 +1,1019 @@
+module RubyVM::MJIT
+  USE_RVARGC = C.USE_RVARGC
+  ROBJECT_EMBED_LEN_MAX = C.ROBJECT_EMBED_LEN_MAX
+
+  UNSUPPORTED_INSNS = [
+    :defineclass, # low priority
+  ]
+
+  # Available variables and macros in JIT-ed function:
+  #   ec: the first argument of _mjitXXX
+  #   reg_cfp: the second argument of _mjitXXX
+  #   GET_CFP(): refers to `reg_cfp`
+  #   GET_EP(): refers to `reg_cfp->ep`
+  #   GET_SP(): refers to `reg_cfp->sp`, or `(stack + stack_size)` if local_stack_p
+  #   GET_SELF(): refers to `cfp_self`
+  #   GET_LEP(): refers to `VM_EP_LEP(reg_cfp->ep)`
+  #   EXEC_EC_CFP(): refers to `val = vm_exec(ec, true)` with frame setup
+  #   CALL_METHOD(): using `GET_CFP()` and `EXEC_EC_CFP()`
+  #   TOPN(): refers to `reg_cfp->sp`, or `*(stack + (stack_size - num - 1))` if local_stack_p
+  #   STACK_ADDR_FROM_TOP(): refers to `reg_cfp->sp`, or `stack + (stack_size - num)` if local_stack_p
+  #   DISPATCH_ORIGINAL_INSN(): expanded in _mjit_compile_insn.erb
+  #   THROW_EXCEPTION(): specially defined for JIT
+  #   RESTORE_REGS(): specially defined for `leave`
+  class << Compiler = Module.new
+    # mjit_compile
+    # @param funcname [String]
+    def compile(f, iseq, funcname, id)
+      status = C.compile_status.new # not freed for now
+      status.compiled_iseq = iseq.body
+      status.compiled_id = id
+      init_compile_status(status, iseq.body, true) # not freed for now
+      if iseq.body.ci_size > 0 && status.cc_entries_index == -1
+        return false
+      end
+
+      init_ivar_compile_status(iseq.body, status)
+
+      if !status.compile_info.disable_send_cache && !status.compile_info.disable_inlining
+        unless precompile_inlinable_iseqs(f, iseq, status)
+          return false
+        end
+      end
+
+      C.fprintf(f, "VALUE\n#{funcname}(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp)\n{\n")
+      success = compile_body(f, iseq, status)
+      C.fprintf(f, "\n} // end of #{funcname}\n")
+
+      return success
+    rescue => e # Should rb_rescue be called in C?
+      if C.mjit_opts.warnings || C.mjit_opts.verbose > 0
+        $stderr.puts e.full_message
+      end
+      return false
+    end
+
+    # mjit_compile_body
+    def compile_body(f, iseq, status)
+      status.success = true
+      status.local_stack_p = !iseq.body.catch_except_p
+
+      if status.local_stack_p
+        src = +"    VALUE stack[#{iseq.body.stack_max}];\n"
+      else
+        src = +"    VALUE *stack = reg_cfp->sp;\n"
+      end
+
+      unless status.inlined_iseqs.nil? # i.e. compile root
+        src << "    static const rb_iseq_t *original_iseq = (const rb_iseq_t *)#{iseq};\n"
+      end
+      src << "    static const VALUE *const original_body_iseq = (VALUE *)#{iseq.body.iseq_encoded};\n"
+
+      src << "    VALUE cfp_self = reg_cfp->self;\n" # cache self across the method
+      src << "#undef GET_SELF\n"
+      src << "#define GET_SELF() cfp_self\n"
+
+      # Generate merged ivar guards first if needed
+      if !status.compile_info.disable_ivar_cache && status.merge_ivar_guards_p
+        src << "    if (UNLIKELY(!(RB_TYPE_P(GET_SELF(), T_OBJECT) && (rb_serial_t)#{status.ivar_serial} == RCLASS_SERIAL(RBASIC(GET_SELF())->klass) &&"
+        if USE_RVARGC
+          src << "#{status.max_ivar_index} < ROBJECT_NUMIV(GET_SELF())" # index < ROBJECT_NUMIV(obj)
+        else
+          if status.max_ivar_index >= ROBJECT_EMBED_LEN_MAX
+            src << "#{status.max_ivar_index} < ROBJECT_NUMIV(GET_SELF())" # index < ROBJECT_NUMIV(obj) && !RB_FL_ANY_RAW(obj, ROBJECT_EMBED)
+          else
+            src << "ROBJECT_EMBED_LEN_MAX == ROBJECT_NUMIV(GET_SELF())" # index < ROBJECT_NUMIV(obj) && RB_FL_ANY_RAW(obj, ROBJECT_EMBED)
+          end
+        end
+        src << "))) {\n"
+        src << "        goto ivar_cancel;\n"
+        src << "    }\n"
+      end
+
+      # Simulate `opt_pc` in setup_parameters_complex. Other PCs which may be passed by catch tables
+      # are not considered since vm_exec doesn't call jit_exec for catch tables.
+      if iseq.body.param.flags.has_opt
+        src << "\n"
+        src << "    switch (reg_cfp->pc - ISEQ_BODY(reg_cfp->iseq)->iseq_encoded) {\n"
+        (0..iseq.body.param.opt_num).each do |i|
+          pc_offset = iseq.body.param.opt_table[i]
+          src << "      case #{pc_offset}:\n"
+          src << "        goto label_#{pc_offset};\n"
+        end
+        src << "    }\n"
+      end
+
+      C.fprintf(f, src)
+      compile_insns(0, 0, status, iseq.body, f)
+      compile_cancel_handler(f, iseq.body, status)
+      C.fprintf(f, "#undef GET_SELF\n")
+      return status.success
+    end
+
+    # Compile one conditional branch. If it has branchXXX insn, this should be
+    # called multiple times for each branch.
+    def compile_insns(stack_size, pos, status, body, f)
+      branch = C.compile_branch.new # not freed for now
+      branch.stack_size = stack_size
+      branch.finish_p = false
+
+      while pos < body.iseq_size && !already_compiled?(status, pos) && !branch.finish_p
+        insn = INSNS.fetch(C.rb_vm_insn_decode(body.iseq_encoded[pos]))
+        status.stack_size_for_pos[pos] = branch.stack_size
+
+        C.fprintf(f, "\nlabel_#{pos}: /* #{insn.name} */\n")
+        pos = compile_insn(insn, pos, status, body.iseq_encoded + (pos+1), body, branch, f)
+        if status.success && branch.stack_size > body.stack_max
+          if mjit_opts.warnings || mjit_opts.verbose > 0
+            $stderr.puts "MJIT warning: JIT stack size (#{branch.stack_size}) exceeded its max size (#{body.stack_max})"
+          end
+          status.success = false
+        end
+        break unless status.success
+      end
+    end
+
+    # Main function of JIT compilation, vm_exec_core counterpart for JIT. Compile one insn to `f`, may modify
+    # b->stack_size and return next position.
+    #
+    # When you add a new instruction to insns.def, it would be nice to have JIT compilation support here but
+    # it's optional. This JIT compiler just ignores ISeq which includes unknown instruction, and ISeq which
+    # does not have it can be compiled as usual.
+    def compile_insn(insn, pos, status, operands, body, b, f)
+      sp_inc = C.mjit_call_attribute_sp_inc(insn.bin, operands)
+      next_pos = pos + insn.len
+
+      result = compile_insn_entry(f, insn, b.stack_size, sp_inc, status.local_stack_p, pos, next_pos, insn.len,
+                                  status.inlined_iseqs.nil?, status, operands, body)
+      if result.nil?
+        if C.mjit_opts.warnings || C.mjit_opts.verbose > 0
+          $stderr.puts "MJIT warning: Skipped to compile unsupported instruction: #{insn.name}"
+        end
+        status.success = false
+      else
+        src, next_pos, finish_p, compile_insns_p = result
+
+        C.fprintf(f, src)
+        b.stack_size += sp_inc
+
+        if finish_p
+          b.finish_p = true
+        end
+        if compile_insns_p
+          if already_compiled?(status, pos + insn.len)
+            C.fprintf(f, "goto label_#{pos + insn.len};\n")
+          else
+            compile_insns(b.stack_size, pos + insn.len, status, body, f)
+          end
+        end
+      end
+
+      # If next_pos is already compiled and this branch is not finished yet,
+      # next instruction won't be compiled in C code next and will need `goto`.
+      if !b.finish_p && next_pos < body.iseq_size && already_compiled?(status, next_pos)
+        C.fprintf(f, "goto label_#{next_pos};\n")
+
+        # Verify stack size assumption is the same among multiple branches
+        if status.stack_size_for_pos[next_pos] != b.stack_size
+          if mjit_opts.warnings || mjit_opts.verbose > 0
+            $stderr.puts "MJIT warning: JIT stack assumption is not the same between branches (#{status.stack_size_for_pos[next_pos]} != #{b.stack_size})\n"
+          end
+          status.success = false
+        end
+      end
+
+      return next_pos
+    end
+
+    # mjit_comiple.inc.erb
+    def compile_insn_entry(f, insn, stack_size, sp_inc, local_stack_p, pos, next_pos, insn_len, inlined_iseq_p, status, operands, body)
+      finish_p = false
+      compile_insns = false
+
+      # TODO: define this outside this method, or at least cache it
+      opt_send_without_block = INSNS.values.find { |i| i.name == :opt_send_without_block }
+      if opt_send_without_block.nil?
+        raise 'opt_send_without_block not found'
+      end
+      send_compatible_opt_insns = INSNS.values.select do |insn|
+        insn.name.start_with?('opt_') && opt_send_without_block.opes == insn.opes &&
+          insn.expr.lines.any? { |l| l.match(/\A\s+CALL_SIMPLE_METHOD\(\);\s+\z/) }
+      end.map(&:name)
+
+      case insn.name
+      when *UNSUPPORTED_INSNS
+        return nil
+      when :opt_send_without_block, :send
+        if src = compile_send(insn, stack_size, sp_inc, local_stack_p, pos, next_pos, status, operands, body)
+          return src, next_pos, finish_p, compile_insns
+        end
+      when *send_compatible_opt_insns
+        if C.has_cache_for_send(captured_cc_entries(status)[call_data_index(C.CALL_DATA.new(operands[0]), body)], insn.bin) &&
+            src = compile_send(opt_send_without_block, stack_size, sp_inc, local_stack_p, pos, next_pos, status, operands, body)
+          return src, next_pos, finish_p, compile_insns
+        end
+      when :getinstancevariable, :setinstancevariable
+        if src = compile_ivar(insn.name, stack_size, pos, status, operands, body)
+          return src, next_pos, finish_p, compile_insns
+        end
+      when :invokebuiltin, :opt_invokebuiltin_delegate
+        if compile_invokebuiltin(f, insn, stack_size, sp_inc, body, operands)
+          return '', next_pos, finish_p, compile_insns
+        end
+      when :opt_getconstant_path
+        if src = compile_getconstant_path(stack_size, pos, insn_len, operands, status)
+          return src, next_pos, finish_p, compile_insns
+        end
+      when :leave, :opt_invokebuiltin_delegate_leave
+        src = +''
+
+        # opt_invokebuiltin_delegate_leave also implements leave insn. We need to handle it here for inlining.
+        if insn.name == :opt_invokebuiltin_delegate_leave
+          compile_invokebuiltin(f, insn, stack_size, sp_inc, body, operands)
+        else
+          if stack_size != 1
+            $stderr.puts "MJIT warning: Unexpected JIT stack_size on leave: #{stack_size}" # TODO: check mjit_opts?
+            return nil
+          end
+        end
+
+        # Skip vm_pop_frame for inlined call
+        unless inlined_iseq_p
+          # Cancel on interrupts to make leave insn leaf
+          src << "    if (UNLIKELY(RUBY_VM_INTERRUPTED_ANY(ec))) {\n"
+          src << "        reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size};\n"
+          src << "        reg_cfp->pc = original_body_iseq + #{pos};\n"
+          src << "        rb_threadptr_execute_interrupts(rb_ec_thread_ptr(ec), 0);\n"
+          src << "    }\n"
+          src << "    ec->cfp = RUBY_VM_PREVIOUS_CONTROL_FRAME(reg_cfp);\n" # vm_pop_frame
+        end
+        src << "    return stack[0];\n"
+        finish_p = true
+        return src, next_pos, finish_p, compile_insns
+      end
+
+      return compile_insn_default(insn, stack_size, sp_inc, local_stack_p, pos, next_pos, insn_len, inlined_iseq_p, operands)
+    rescue => e
+      puts e.full_message
+      nil
+    end
+
+    private
+
+    # Optimized case of send / opt_send_without_block instructions.
+    # _mjit_compile_send.erb
+    def compile_send(insn, stack_size, sp_inc, local_stack_p, pos, next_pos, status, operands, body)
+      # compiler: Use captured cc to avoid race condition
+      cd = C.CALL_DATA.new(operands[0])
+      cd_index = call_data_index(cd, body)
+      captured_cc = captured_cc_entries(status)[cd_index]
+
+      # compiler: Inline send insn where some supported fastpath is used.
+      ci = cd.ci
+      kw_splat = (C.vm_ci_flag(ci) & C.VM_CALL_KW_SPLAT) > 0
+      if !status.compile_info.disable_send_cache && has_valid_method_type?(captured_cc) && (
+          # `CC_SET_FASTPATH(cd->cc, vm_call_cfunc_with_frame, ...)` in `vm_call_cfunc`
+          (vm_cc_cme(captured_cc).def.type == C.VM_METHOD_TYPE_CFUNC && !C.rb_splat_or_kwargs_p(ci) && !kw_splat) ||
+          # `CC_SET_FASTPATH(cc, vm_call_iseq_setup_func(...), vm_call_iseq_optimizable_p(...))` in `vm_callee_setup_arg`,
+          # and support only non-VM_CALL_TAILCALL path inside it
+          (vm_cc_cme(captured_cc).def.type == C.VM_METHOD_TYPE_ISEQ &&
+           C.fastpath_applied_iseq_p(ci, captured_cc, iseq = def_iseq_ptr(vm_cc_cme(captured_cc).def)) &&
+           (C.vm_ci_flag(ci) & C.VM_CALL_TAILCALL) == 0)
+      )
+        src = +"{\n"
+
+        # JIT: Invalidate call cache if it requires vm_search_method. This allows to inline some of following things.
+        src << "    const struct rb_callcache *cc = (struct rb_callcache *)#{captured_cc};\n"
+        src << "    const rb_callable_method_entry_t *cc_cme = (rb_callable_method_entry_t *)#{vm_cc_cme(captured_cc)};\n"
+        src << "    const VALUE recv = stack[#{stack_size + sp_inc - 1}];\n"
+        # If opt_class_of is true, use RBASIC_CLASS instead of CLASS_OF to reduce code size
+        opt_class_of = !maybe_special_const?(captured_cc.klass)
+        src << "    if (UNLIKELY(#{opt_class_of ? 'RB_SPECIAL_CONST_P(recv)' : 'false'} || !vm_cc_valid_p(cc, cc_cme, #{opt_class_of ? 'RBASIC_CLASS' : 'CLASS_OF'}(recv)))) {\n"
+        src << "        reg_cfp->pc = original_body_iseq + #{pos};\n"
+        src << "        reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size};\n"
+        src << "        goto send_cancel;\n"
+        src << "    }\n"
+
+        # JIT: move sp and pc if necessary
+        pc_moved_p = compile_pc_and_sp(src, insn, stack_size, sp_inc, local_stack_p, next_pos)
+
+        # JIT: If ISeq is inlinable, call the inlined method without pushing a frame.
+        if iseq && status.inlined_iseqs && iseq.body.to_i == status.inlined_iseqs[pos]&.to_i
+          src << "    {\n"
+          src << "        VALUE orig_self = reg_cfp->self;\n"
+          src << "        reg_cfp->self = stack[#{stack_size + sp_inc - 1}];\n"
+          src << "        stack[#{stack_size + sp_inc - 1}] = _mjit#{status.compiled_id}_inlined_#{pos}(ec, reg_cfp, orig_self, original_iseq);\n"
+          src << "        reg_cfp->self = orig_self;\n"
+          src << "    }\n"
+        else
+          # JIT: Forked `vm_sendish` (except method_explorer = vm_search_method_wrap) to inline various things
+          src << "    {\n"
+          src << "        VALUE val;\n"
+          src << "        struct rb_calling_info calling;\n"
+          if insn.name == :send
+            src << "        calling.block_handler = vm_caller_setup_arg_block(ec, reg_cfp, (const struct rb_callinfo *)#{ci}, (rb_iseq_t *)0x#{operands[1].to_s(16)}, FALSE);\n"
+          else
+            src << "        calling.block_handler = VM_BLOCK_HANDLER_NONE;\n"
+          end
+          src << "        calling.kw_splat = #{kw_splat ? 1 : 0};\n"
+          src << "        calling.recv = stack[#{stack_size + sp_inc - 1}];\n"
+          src << "        calling.argc = #{C.vm_ci_argc(ci)};\n"
+
+          if vm_cc_cme(captured_cc).def.type == C.VM_METHOD_TYPE_CFUNC
+            # TODO: optimize this more
+            src << "        calling.ci = (const struct rb_callinfo *)#{ci};\n" # creating local cd here because operand's cd->cc may not be the same as inlined cc.
+            src << "        calling.cc = cc;"
+            src << "        val = vm_call_cfunc_with_frame(ec, reg_cfp, &calling);\n"
+          else # :iseq
+            # fastpath_applied_iseq_p checks rb_simple_iseq_p, which ensures has_opt == FALSE
+            src << "        vm_call_iseq_setup_normal(ec, reg_cfp, &calling, cc_cme, 0, #{iseq.body.param.size}, #{iseq.body.local_table_size});\n"
+            if iseq.body.catch_except_p
+              src << "        VM_ENV_FLAGS_SET(ec->cfp->ep, VM_FRAME_FLAG_FINISH);\n"
+              src << "        val = vm_exec(ec, true);\n"
+            else
+              src << "        if ((val = jit_exec(ec)) == Qundef) {\n"
+              src << "            VM_ENV_FLAGS_SET(ec->cfp->ep, VM_FRAME_FLAG_FINISH);\n" # This is vm_call0_body's code after vm_call_iseq_setup
+              src << "            val = vm_exec(ec, false);\n"
+              src << "        }\n"
+            end
+          end
+          src << "        stack[#{stack_size + sp_inc - 1}] = val;\n"
+          src << "    }\n"
+
+          # JIT: We should evaluate ISeq modified for TracePoint if it's enabled. Note: This is slow.
+          src << "    if (UNLIKELY(!mjit_call_p)) {\n"
+          src << "        reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size + sp_inc};\n"
+          if !pc_moved_p
+            src << "        reg_cfp->pc = original_body_iseq + #{next_pos};\n"
+          end
+          src << "        RB_DEBUG_COUNTER_INC(mjit_cancel_invalidate_all);\n"
+          src << "        goto cancel;\n"
+          src << "    }\n"
+        end
+
+        src << "}\n"
+        return src
+      else
+        return nil
+      end
+    end
+
+    # _mjit_compile_ivar.erb
+    def compile_ivar(insn_name, stack_size, pos, status, operands, body)
+      ic_copy = (status.is_entries + (C.iseq_inline_storage_entry.new(operands[1]) - body.is_entries)).iv_cache
+
+      src = +''
+      if !status.compile_info.disable_ivar_cache && ic_copy.entry
+        # JIT: optimize away motion of sp and pc. This path does not call rb_warning() and so it's always leaf and not `handles_sp`.
+        # compile_pc_and_sp(src, insn, stack_size, sp_inc, local_stack_p, next_pos)
+
+        # JIT: prepare vm_getivar/vm_setivar arguments and variables
+        src << "{\n"
+        src << "    VALUE obj = GET_SELF();\n"
+        src << "    const uint32_t index = #{ic_copy.entry.index};\n"
+        if status.merge_ivar_guards_p
+          # JIT: Access ivar without checking these VM_ASSERTed prerequisites as we checked them in the beginning of `mjit_compile_body`
+          src << "    VM_ASSERT(RB_TYPE_P(obj, T_OBJECT));\n"
+          src << "    VM_ASSERT((rb_serial_t)#{ic_copy.entry.class_serial} == RCLASS_SERIAL(RBASIC(obj)->klass));\n"
+          src << "    VM_ASSERT(index < ROBJECT_NUMIV(obj));\n"
+          if insn_name == :setinstancevariable
+            if USE_RVARGC
+              src << "    if (LIKELY(!RB_OBJ_FROZEN_RAW(obj) && index < ROBJECT_NUMIV(obj))) {\n"
+              src << "        RB_OBJ_WRITE(obj, &ROBJECT_IVPTR(obj)[index], stack[#{stack_size - 1}]);\n"
+            else
+              heap_ivar_p = status.max_ivar_index >= ROBJECT_EMBED_LEN_MAX
+              src << "    if (LIKELY(!RB_OBJ_FROZEN_RAW(obj) && #{heap_ivar_p ? 'true' : 'RB_FL_ANY_RAW(obj, ROBJECT_EMBED)'})) {\n"
+              src << "        RB_OBJ_WRITE(obj, &ROBJECT(obj)->as.#{heap_ivar_p ? 'heap.ivptr[index]' : 'ary[index]'}, stack[#{stack_size - 1}]);\n"
+            end
+            src << "    }\n"
+          else
+            src << "    VALUE val;\n"
+            if USE_RVARGC
+              src << "    if (LIKELY(index < ROBJECT_NUMIV(obj) && (val = ROBJECT_IVPTR(obj)[index]) != Qundef)) {\n"
+            else
+              heap_ivar_p = status.max_ivar_index >= ROBJECT_EMBED_LEN_MAX
+              src << "    if (LIKELY(#{heap_ivar_p ? 'true' : 'RB_FL_ANY_RAW(obj, ROBJECT_EMBED)'} && (val = ROBJECT(obj)->as.#{heap_ivar_p ? 'heap.ivptr[index]' : 'ary[index]'}) != Qundef)) {\n"
+            end
+            src << "        stack[#{stack_size}] = val;\n"
+            src << "    }\n"
+          end
+        else
+          src << "    const rb_serial_t ic_serial = (rb_serial_t)#{ic_copy.entry.class_serial};\n"
+          # JIT: cache hit path of vm_getivar/vm_setivar, or cancel JIT (recompile it with exivar)
+          if insn_name == :setinstancevariable
+            src << "    if (LIKELY(RB_TYPE_P(obj, T_OBJECT) && ic_serial == RCLASS_SERIAL(RBASIC(obj)->klass) && index < ROBJECT_NUMIV(obj) && !RB_OBJ_FROZEN_RAW(obj))) {\n"
+            src << "        VALUE *ptr = ROBJECT_IVPTR(obj);\n"
+            src << "        RB_OBJ_WRITE(obj, &ptr[index], stack[#{stack_size - 1}]);\n"
+            src << "    }\n"
+          else
+            src << "    VALUE val;\n"
+            src << "    if (LIKELY(RB_TYPE_P(obj, T_OBJECT) && ic_serial == RCLASS_SERIAL(RBASIC(obj)->klass) && index < ROBJECT_NUMIV(obj) && (val = ROBJECT_IVPTR(obj)[index]) != Qundef)) {\n"
+            src << "        stack[#{stack_size}] = val;\n"
+            src << "    }\n"
+          end
+        end
+        src << "    else {\n"
+        src << "        reg_cfp->pc = original_body_iseq + #{pos};\n"
+        src << "        reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size};\n"
+        src << "        goto ivar_cancel;\n"
+        src << "    }\n"
+        src << "}\n"
+        return src
+      elsif insn_name == :getinstancevariable && !status.compile_info.disable_exivar_cache && ic_copy.entry
+        # JIT: optimize away motion of sp and pc. This path does not call rb_warning() and so it's always leaf and not `handles_sp`.
+        # compile_pc_and_sp(src, insn, stack_size, sp_inc, local_stack_p, next_pos)
+
+        # JIT: prepare vm_getivar's arguments and variables
+        src << "{\n"
+        src << "    VALUE obj = GET_SELF();\n"
+        src << "    const rb_serial_t ic_serial = (rb_serial_t)#{ic_copy.entry.class_serial};\n"
+        src << "    const uint32_t index = #{ic_copy.entry.index};\n"
+        # JIT: cache hit path of vm_getivar, or cancel JIT (recompile it without any ivar optimization)
+        src << "    struct gen_ivtbl *ivtbl;\n"
+        src << "    VALUE val;\n"
+        src << "    if (LIKELY(FL_TEST_RAW(obj, FL_EXIVAR) && ic_serial == RCLASS_SERIAL(RBASIC(obj)->klass) && rb_ivar_generic_ivtbl_lookup(obj, &ivtbl) && index < ivtbl->numiv && (val = ivtbl->ivptr[index]) != Qundef)) {\n"
+        src << "        stack[#{stack_size}] = val;\n"
+        src << "    }\n"
+        src << "    else {\n"
+        src << "        reg_cfp->pc = original_body_iseq + #{pos};\n"
+        src << "        reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size};\n"
+        src << "        goto exivar_cancel;\n"
+        src << "    }\n"
+        src << "}\n"
+        return src
+      else
+        return nil
+      end
+    end
+
+    # _mjit_compile_invokebulitin.erb
+    def compile_invokebuiltin(f, insn, stack_size, sp_inc, body, operands)
+      bf = C.RB_BUILTIN.new(operands[0])
+      if bf.compiler > 0
+        C.fprintf(f, "{\n")
+        C.fprintf(f, "    VALUE val;\n")
+        C.builtin_compiler(f, bf, operands[1], stack_size, body.builtin_inline_p)
+        C.fprintf(f, "    stack[#{stack_size + sp_inc - 1}] = val;\n")
+        C.fprintf(f, "}\n")
+        return true
+      else
+        return false
+      end
+    end
+
+    # _mjit_compile_getconstant_path.erb
+    def compile_getconstant_path(stack_size, pos, insn_len, operands, status)
+      ice = C.IC.new(operands[0]).entry
+      if !status.compile_info.disable_const_cache && ice
+        # JIT: Inline everything in IC, and cancel the slow path
+        src = +"    if (vm_inlined_ic_hit_p(#{ice.flags}, #{ice.value}, (const rb_cref_t *)#{to_addr(ice.ic_cref)}, reg_cfp->ep)) {\n"
+        src << "        stack[#{stack_size}] = #{ice.value};\n"
+        src << "    }\n"
+        src << "    else {\n"
+        src << "        reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size};\n"
+        src << "        reg_cfp->pc = original_body_iseq + #{pos};\n"
+        src << "        goto const_cancel;\n"
+        src << "    }\n"
+        return src
+      else
+        return nil
+      end
+    end
+
+    # _mjit_compile_insn.erb
+    def compile_insn_default(insn, stack_size, sp_inc, local_stack_p, pos, next_pos, insn_len, inlined_iseq_p, operands)
+      src = +''
+      finish_p = false
+      compile_insns = false
+
+      # JIT: Declare stack_size to be used in some macro of _mjit_compile_insn_body.erb
+      src << "{\n"
+      if local_stack_p
+        src << "    MAYBE_UNUSED(unsigned int) stack_size = #{stack_size};\n"
+      end
+
+      # JIT: Declare variables for operands, popped values and return values
+      insn.declarations.each do |decl|
+        src << "    #{decl};\n"
+      end
+
+      # JIT: Set const expressions for `RubyVM::OperandsUnifications` insn
+      insn.preamble.each do |amble|
+        src << "#{amble.sub(/const \S+\s+/, '')}\n"
+      end
+
+      # JIT: Initialize operands
+      insn.opes.each_with_index do |ope, i|
+        src << "    #{ope.fetch(:name)} = (#{ope.fetch(:type)})#{operands[i]};\n"
+        # TODO: resurrect comment_id
+      end
+
+      # JIT: Initialize popped values
+      insn.pops.reverse_each.with_index.reverse_each do |pop, i|
+        src << "    #{pop.fetch(:name)} = stack[#{stack_size - (i + 1)}];\n"
+      end
+
+      # JIT: move sp and pc if necessary
+      pc_moved_p = compile_pc_and_sp(src, insn, stack_size, sp_inc, local_stack_p, next_pos)
+
+      # JIT: Print insn body in insns.def
+      next_pos = compile_insn_body(src, insn, pos, next_pos, insn_len, local_stack_p, stack_size, sp_inc, operands)
+
+      # JIT: Set return values
+      insn.rets.reverse_each.with_index do |ret, i|
+        # TOPN(n) = ...
+        src << "    stack[#{stack_size + sp_inc - (i + 1)}] = #{ret.fetch(:name)};\n"
+      end
+
+      # JIT: We should evaluate ISeq modified for TracePoint if it's enabled. Note: This is slow.
+      #      leaf insn may not cancel JIT. leaf_without_check_ints is covered in RUBY_VM_CHECK_INTS of _mjit_compile_insn_body.erb.
+      unless insn.always_leaf? || insn.leaf_without_check_ints?
+        src << "    if (UNLIKELY(!mjit_call_p)) {\n"
+        src << "        reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size + sp_inc};\n"
+        if !pc_moved_p
+          src << "        reg_cfp->pc = original_body_iseq + #{next_pos};\n"
+        end
+        src << "        RB_DEBUG_COUNTER_INC(mjit_cancel_invalidate_all);\n"
+        src << "        goto cancel;\n"
+        src << "    }\n"
+      end
+
+      src << "}\n"
+
+      # compiler: If insn has conditional JUMP, the code should go to the branch not targeted by JUMP next.
+      if insn.expr.match?(/if\s+\([^{}]+\)\s+\{[^{}]+JUMP\([^)]+\);[^{}]+\}/)
+        compile_insns = true
+      end
+
+      # compiler: If insn returns (leave) or does longjmp (throw), the branch should no longer be compiled. TODO: create attr for it?
+      if insn.expr.match?(/\sTHROW_EXCEPTION\([^)]+\);/) || insn.expr.match?(/\bvm_pop_frame\(/)
+        finish_p = true
+      end
+
+      return src, next_pos, finish_p, compile_insns
+    end
+
+    # _mjit_compile_insn_body.erb
+    def compile_insn_body(src, insn, pos, next_pos, insn_len, local_stack_p, stack_size, sp_inc, operands)
+      # Print a body of insn, but with macro expansion.
+      expand_simple_macros(insn.expr).each_line do |line|
+        # Expand dynamic macro here
+        # TODO: support combination of following macros in the same line
+        case line
+        when /\A\s+RUBY_VM_CHECK_INTS\(ec\);\s+\z/
+          if insn.leaf_without_check_ints? # lazily move PC and optionalize mjit_call_p here
+            src << "            if (UNLIKELY(RUBY_VM_INTERRUPTED_ANY(ec))) {\n"
+            src << "                reg_cfp->pc = original_body_iseq + #{next_pos};\n" # ADD_PC(INSN_ATTR(width));
+            src << "                rb_threadptr_execute_interrupts(rb_ec_thread_ptr(ec), 0);\n"
+            src << "                if (UNLIKELY(!mjit_call_p)) {\n"
+            src << "                    reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size};\n"
+            src << "                    RB_DEBUG_COUNTER_INC(mjit_cancel_invalidate_all);\n"
+            src << "                    goto cancel;\n"
+            src << "                }\n"
+            src << "            }\n"
+          else
+            src << to_cstr(line)
+          end
+        when /\A\s+JUMP\((?<dest>[^)]+)\);\s+\z/
+          dest = Regexp.last_match[:dest]
+          if insn.name == :opt_case_dispatch # special case... TODO: use another macro to avoid checking name
+            else_offset = cast_offset(operands[1])
+            cdhash = C.cdhash_to_hash(operands[0])
+            base_pos = pos + insn_len
+
+            src << "    switch (#{dest}) {\n"
+            cdhash.each do |_key, offset|
+              src << "      case #{offset}:\n"
+              src << "        goto label_#{base_pos + offset};\n"
+            end
+            src << "      case #{else_offset}:\n"
+            src << "        goto label_#{base_pos + else_offset};\n"
+            src << "    }\n"
+          else
+            # Before we `goto` next insn, we need to set return values, especially for getinlinecache
+            insn.rets.reverse_each.with_index do |ret, i|
+              # TOPN(n) = ...
+              src << "            stack[#{stack_size + sp_inc - (i + 1)}] = #{ret.fetch(:name)};\n"
+            end
+
+            next_pos = pos + insn_len + cast_offset(operands[0]) # workaround: assuming dest == operands[0]. TODO: avoid relying on it
+            src << "            goto label_#{next_pos};\n"
+          end
+        when /\A\s+CALL_SIMPLE_METHOD\(\);\s+\z/
+          # For `opt_xxx`'s fallbacks.
+          if local_stack_p
+            src << "            reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size};\n"
+          end
+          src << "            reg_cfp->pc = original_body_iseq + #{pos};\n"
+          src << "            RB_DEBUG_COUNTER_INC(mjit_cancel_opt_insn);\n"
+          src << "            goto cancel;\n"
+        when /\A(?<prefix>.+\b)INSN_LABEL\((?<name>[^)]+)\)(?<suffix>.+)\z/m
+          prefix, name, suffix = Regexp.last_match[:prefix], Regexp.last_match[:name], Regexp.last_match[:suffix]
+          src << "#{prefix}INSN_LABEL(#{name}_#{pos})#{suffix}"
+        else
+          if insn.handles_sp?
+            # If insn.handles_sp? is true, cfp->sp might be changed inside insns (like vm_caller_setup_arg_block)
+            # and thus we need to use cfp->sp, even when local_stack_p is TRUE. When insn.handles_sp? is true,
+            # cfp->sp should be available too because _mjit_compile_pc_and_sp.erb sets it.
+            src << to_cstr(line)
+          else
+            # If local_stack_p is TRUE and insn.handles_sp? is false, stack values are only available in local variables
+            # for stack. So we need to replace those macros if local_stack_p is TRUE here.
+            case line
+            when /\bGET_SP\(\)/
+              # reg_cfp->sp
+              src << to_cstr(line.sub(/\bGET_SP\(\)/, local_stack_p ? '(stack + stack_size)' : 'GET_SP()'))
+            when /\bSTACK_ADDR_FROM_TOP\((?<num>[^)]+)\)/
+              # #define STACK_ADDR_FROM_TOP(n) (GET_SP()-(n))
+              num = Regexp.last_match[:num]
+              src << to_cstr(line.sub(/\bSTACK_ADDR_FROM_TOP\(([^)]+)\)/, local_stack_p ? "(stack + (stack_size - (#{num})))" : "STACK_ADDR_FROM_TOP(#{num})"))
+            when /\bTOPN\((?<num>[^)]+)\)/
+              # #define TOPN(n) (*(GET_SP()-(n)-1))
+              num = Regexp.last_match[:num]
+              src << to_cstr(line.sub(/\bTOPN\(([^)]+)\)/, local_stack_p ? "*(stack + (stack_size - (#{num}) - 1))" : "TOPN(#{num})"))
+            else
+              src << to_cstr(line)
+            end
+          end
+        end
+      end
+      return next_pos
+    end
+
+    # _mjit_compile_pc_and_sp.erb
+    def compile_pc_and_sp(src, insn, stack_size, sp_inc, local_stack_p, next_pos)
+      # JIT: When an insn is leaf, we don't need to Move pc for a catch table on catch_except_p, #caller_locations,
+      #      and rb_profile_frames. For check_ints, we lazily move PC when we have interruptions.
+      pc_moved_p = false
+      unless insn.always_leaf? || insn.leaf_without_check_ints?
+        src << "    reg_cfp->pc = original_body_iseq + #{next_pos};\n" # ADD_PC(INSN_ATTR(width));
+        pc_moved_p = true
+      end
+
+      # JIT: move sp to use or preserve stack variables
+      if local_stack_p
+        # sp motion is optimized away for `handles_sp? #=> false` case.
+        # Thus sp should be set properly before `goto cancel`.
+        if insn.handles_sp?
+          # JIT-only behavior (pushing JIT's local variables to VM's stack):
+          push_size = -sp_inc + insn.rets.size - insn.pops.size
+          src << "    reg_cfp->sp = vm_base_ptr(reg_cfp) + #{push_size};\n"
+          push_size.times do |i|
+            src << "    *(reg_cfp->sp + #{i - push_size}) = stack[#{stack_size - push_size + i}];\n"
+          end
+        end
+      else
+        if insn.handles_sp?
+          src << "    reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size - insn.pops.size};\n" # POPN(INSN_ATTR(popn));
+        else
+          src << "    reg_cfp->sp = vm_base_ptr(reg_cfp) + #{stack_size};\n"
+        end
+      end
+      return pc_moved_p
+    end
+
+    # Print the block to cancel inlined method call. It's supporting only `opt_send_without_block` for now.
+    def compile_inlined_cancel_handler(f, body, inline_context)
+      src = +"\ncancel:\n"
+      src << "    RB_DEBUG_COUNTER_INC(mjit_cancel);\n"
+      src << "    rb_mjit_recompile_inlining(original_iseq);\n"
+
+      # Swap pc/sp set on cancel with original pc/sp.
+      src << "    const VALUE *current_pc = reg_cfp->pc;\n"
+      src << "    VALUE *current_sp = reg_cfp->sp;\n"
+      src << "    reg_cfp->pc = orig_pc;\n"
+      src << "    reg_cfp->sp = orig_sp;\n\n"
+
+      # Lazily push the current call frame.
+      src << "    struct rb_calling_info calling;\n"
+      src << "    calling.block_handler = VM_BLOCK_HANDLER_NONE;\n" # assumes `opt_send_without_block`
+      src << "    calling.argc = #{inline_context.orig_argc};\n"
+      src << "    calling.recv = reg_cfp->self;\n"
+      src << "    reg_cfp->self = orig_self;\n"
+      # fastpath_applied_iseq_p checks rb_simple_iseq_p, which ensures has_opt == FALSE
+      src << "    vm_call_iseq_setup_normal(ec, reg_cfp, &calling, (const rb_callable_method_entry_t *)#{inline_context.me}, 0, #{inline_context.param_size}, #{inline_context.local_size});\n\n"
+
+      # Start usual cancel from here.
+      src << "    reg_cfp = ec->cfp;\n" # work on the new frame
+      src << "    reg_cfp->pc = current_pc;\n"
+      src << "    reg_cfp->sp = current_sp;\n"
+      (0...body.stack_max).each do |i| # should be always `status->local_stack_p`
+        src << "    *(vm_base_ptr(reg_cfp) + #{i}) = stack[#{i}];\n"
+      end
+      # We're not just returning Qundef here so that caller's normal cancel handler can
+      # push back `stack` to `cfp->sp`.
+      src << "    return vm_exec(ec, false);\n"
+      C.fprintf(f, src)
+    end
+
+    # Print the block to cancel JIT execution.
+    def compile_cancel_handler(f, body, status)
+      if status.inlined_iseqs.nil? # the current ISeq is being inlined
+        compile_inlined_cancel_handler(f, body, status.inline_context)
+        return
+      end
+
+      src = +"\nsend_cancel:\n"
+      src << "    RB_DEBUG_COUNTER_INC(mjit_cancel_send_inline);\n"
+      src << "    rb_mjit_recompile_send(original_iseq);\n"
+      src << "    goto cancel;\n"
+
+      src << "\nivar_cancel:\n"
+      src << "    RB_DEBUG_COUNTER_INC(mjit_cancel_ivar_inline);\n"
+      src << "    rb_mjit_recompile_ivar(original_iseq);\n"
+      src << "    goto cancel;\n"
+
+      src << "\nexivar_cancel:\n"
+      src << "    RB_DEBUG_COUNTER_INC(mjit_cancel_exivar_inline);\n"
+      src << "    rb_mjit_recompile_exivar(original_iseq);\n"
+      src << "    goto cancel;\n"
+
+      src << "\nconst_cancel:\n"
+      src << "    rb_mjit_recompile_const(original_iseq);\n"
+      src << "    goto cancel;\n"
+
+      src << "\ncancel:\n"
+      src << "    RB_DEBUG_COUNTER_INC(mjit_cancel);\n"
+      if status.local_stack_p
+        (0...body.stack_max).each do |i|
+          src << "    *(vm_base_ptr(reg_cfp) + #{i}) = stack[#{i}];\n"
+        end
+      end
+      src << "    return Qundef;\n"
+      C.fprintf(f, src)
+    end
+
+    def precompile_inlinable_child_iseq(f, child_iseq, status, ci, cc, pos)
+      child_status = C.compile_status.new # not freed for now
+      child_status.compiled_iseq = status.compiled_iseq
+      child_status.compiled_id = status.compiled_id
+      init_compile_status(child_status, child_iseq.body, false) # not freed for now
+      child_status.inline_context.orig_argc = C.vm_ci_argc(ci)
+      child_status.inline_context.me = vm_cc_cme(cc).to_i
+      child_status.inline_context.param_size = child_iseq.body.param.size
+      child_status.inline_context.local_size = child_iseq.body.local_table_size
+      if child_iseq.body.ci_size > 0 && child_status.cc_entries_index == -1
+        return false
+      end
+      init_ivar_compile_status(child_iseq.body, child_status)
+
+      src = +"ALWAYS_INLINE(static VALUE _mjit#{status.compiled_id}_inlined_#{pos}(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, const VALUE orig_self, const rb_iseq_t *original_iseq));\n"
+      src << "static inline VALUE\n_mjit#{status.compiled_id}_inlined_#{pos}(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, const VALUE orig_self, const rb_iseq_t *original_iseq)\n{\n"
+      src << "    const VALUE *orig_pc = reg_cfp->pc;\n"
+      src << "    VALUE *orig_sp = reg_cfp->sp;\n"
+      C.fprintf(f, src)
+
+      success = compile_body(f, child_iseq, child_status)
+
+      C.fprintf(f, "\n} /* end of _mjit#{status.compiled_id}_inlined_#{pos} */\n\n")
+
+      return success;
+    end
+
+    def precompile_inlinable_iseqs(f, iseq, status)
+      body = iseq.body
+      pos = 0
+      while pos < body.iseq_size
+        insn = INSNS.fetch(C.rb_vm_insn_decode(body.iseq_encoded[pos]))
+        if insn.name == :opt_send_without_block || insn.name == :opt_size # `compile_inlined_cancel_handler` supports only `opt_send_without_block`
+          cd = C.CALL_DATA.new(body.iseq_encoded[pos + 1])
+          ci = cd.ci
+          cc = captured_cc_entries(status)[call_data_index(cd, body)] # use copy to avoid race condition
+
+          if (child_iseq = rb_mjit_inlinable_iseq(ci, cc)) != nil
+            status.inlined_iseqs[pos] = child_iseq.body
+
+            if C.mjit_opts.verbose >= 1 # print beforehand because ISeq may be GCed during copy job.
+              child_location = child_iseq.body.location
+              $stderr.puts "JIT inline: #{child_location.label}@#{C.rb_iseq_path(child_iseq)}:#{child_location.first_lineno} " \
+                "=> #{iseq.body.location.label}@#{C.rb_iseq_path(iseq)}:#{iseq.body.location.first_lineno}"
+            end
+            if !precompile_inlinable_child_iseq(f, child_iseq, status, ci, cc, pos)
+              return false
+            end
+          end
+        end
+        pos += insn.len
+      end
+      return true
+    end
+
+    def init_compile_status(status, body, compile_root_p)
+      status.stack_size_for_pos = Fiddle.malloc(Fiddle::SIZEOF_INT * body.iseq_size)
+      body.iseq_size.times do |i|
+        status.stack_size_for_pos[i] = C.NOT_COMPILED_STACK_SIZE
+      end
+      if compile_root_p
+        status.inlined_iseqs = Fiddle.malloc(Fiddle::SIZEOF_VOIDP * body.iseq_size)
+        body.iseq_size.times do |i|
+          status.inlined_iseqs[i] = nil
+        end
+      end
+      if ISEQ_IS_SIZE(body) > 0
+        status.is_entries = Fiddle.malloc(C.iseq_inline_storage_entry.sizeof * ISEQ_IS_SIZE(body))
+      end
+      if body.ci_size > 0
+        status.cc_entries_index = C.mjit_capture_cc_entries(status.compiled_iseq, body)
+      else
+        status.cc_entries_index = -1
+      end
+      if compile_root_p
+        status.compile_info = rb_mjit_iseq_compile_info(body)
+      else
+        status.compile_info = Fiddle.malloc(C.rb_mjit_compile_info.sizeof)
+        status.compile_info.disable_ivar_cache = false
+        status.compile_info.disable_exivar_cache = false
+        status.compile_info.disable_send_cache = false
+        status.compile_info.disable_inlining = false
+        status.compile_info.disable_const_cache = false
+      end
+    end
+
+    def init_ivar_compile_status(body, status)
+      C.mjit_capture_is_entries(body, status.is_entries)
+
+      num_ivars = 0
+      pos = 0
+      status.max_ivar_index = 0
+      status.ivar_serial = 0
+
+      while pos < body.iseq_size
+        insn = INSNS.fetch(C.rb_vm_insn_decode(body.iseq_encoded[pos]))
+        if insn.name == :getinstancevariable || insn.name == :setinstancevariable
+          ic = body.iseq_encoded[pos+2]
+          ic_copy = (status.is_entries + (C.iseq_inline_storage_entry.new(ic) - body.is_entries)).iv_cache
+          if ic_copy.entry # Only initialized (ic_serial > 0) IVCs are optimized
+            num_ivars += 1
+
+            if status.max_ivar_index < ic_copy.entry.index
+              status.max_ivar_index = ic_copy.entry.index
+            end
+
+            if status.ivar_serial == 0
+              status.ivar_serial = ic_copy.entry.class_serial
+            elsif status.ivar_serial != ic_copy.entry.class_serial
+              # Multiple classes have used this ISeq. Give up assuming one serial.
+              status.merge_ivar_guards_p = false
+              return
+            end
+          end
+        end
+        pos += insn.len
+      end
+      status.merge_ivar_guards_p = status.ivar_serial > 0 && num_ivars >= 2
+    end
+
+    # Expand simple macro that doesn't require dynamic C code.
+    def expand_simple_macros(arg_expr)
+      arg_expr.dup.tap do |expr|
+        # For `leave`. We can't proceed next ISeq in the same JIT function.
+        expr.gsub!(/^(?<indent>\s*)RESTORE_REGS\(\);\n/) do
+          indent = Regexp.last_match[:indent]
+          <<-end.gsub(/^ {12}/, '')
+            #if OPT_CALL_THREADED_CODE
+            #{indent}rb_ec_thread_ptr(ec)->retval = val;
+            #{indent}return 0;
+            #else
+            #{indent}return val;
+            #endif
+          end
+        end
+        expr.gsub!(/^(?<indent>\s*)NEXT_INSN\(\);\n/) do
+          indent = Regexp.last_match[:indent]
+          <<-end.gsub(/^ {12}/, '')
+            #{indent}UNREACHABLE_RETURN(Qundef);
+          end
+        end
+      end
+    end
+
+    def to_cstr(expr)
+      expr.gsub(/^(?!#)/, '    ') # indent everything but preprocessor lines
+    end
+
+    # Interpret unsigned long as signed long (VALUE -> OFFSET)
+    def cast_offset(offset)
+      bits = "%0#{8 * Fiddle::SIZEOF_VOIDP}d" % offset.to_s(2)
+      if bits[0] == '1' # negative
+        offset = -bits.chars.map { |i| i == '0' ? '1' : '0' }.join.to_i(2) - 1
+      end
+      offset
+    end
+
+    def captured_cc_entries(status)
+      status.compiled_iseq.jit_unit.cc_entries + status.cc_entries_index
+    end
+
+    def call_data_index(cd, body)
+      cd - body.call_data
+    end
+
+    def vm_cc_cme(cc)
+      # TODO: add VM_ASSERT like actual vm_cc_cme
+      cc.cme_
+    end
+
+    def def_iseq_ptr(method_def)
+      C.rb_iseq_check(method_def.body.iseq.iseqptr)
+    end
+
+    def rb_mjit_iseq_compile_info(body)
+      body.jit_unit.compile_info
+    end
+
+    def ISEQ_IS_SIZE(body)
+      body.ic_size + body.ivc_size + body.ise_size + body.icvarc_size
+    end
+
+    # Return true if an object of the class may be a special const (immediate).
+    # It's "maybe" because Integer and Float are not guaranteed to be an immediate.
+    # If this returns false, rb_class_of could be optimzied to RBASIC_CLASS.
+    def maybe_special_const?(klass)
+      [
+        C.rb_cFalseClass,
+        C.rb_cNilClass,
+        C.rb_cTrueClass,
+        C.rb_cInteger,
+        C.rb_cSymbol,
+        C.rb_cFloat,
+      ].include?(klass)
+    end
+
+    def has_valid_method_type?(cc)
+      vm_cc_cme(cc) != nil
+    end
+
+    def already_compiled?(status, pos)
+      status.stack_size_for_pos[pos] != C.NOT_COMPILED_STACK_SIZE
+    end
+
+    # Return an iseq pointer if cc has inlinable iseq.
+    def rb_mjit_inlinable_iseq(ci, cc)
+      if has_valid_method_type?(cc) &&
+          C.vm_ci_flag(ci) & C.VM_CALL_TAILCALL == 0 && # inlining only non-tailcall path
+          vm_cc_cme(cc).def.type == C.VM_METHOD_TYPE_ISEQ &&
+          C.fastpath_applied_iseq_p(ci, cc, iseq = def_iseq_ptr(vm_cc_cme(cc).def)) &&
+          inlinable_iseq_p(iseq.body) # CC_SET_FASTPATH in vm_callee_setup_arg
+        return iseq
+      end
+      return nil
+    end
+
+    # Return true if the ISeq can be inlined without pushing a new control frame.
+    def inlinable_iseq_p(body)
+      # 1) If catch_except_p, caller frame should be preserved when callee catches an exception.
+      # Then we need to wrap `vm_exec()` but then we can't inline the call inside it.
+      #
+      # 2) If `body->catch_except_p` is false and `handles_sp?` of an insn is false,
+      # sp is not moved as we assume `status->local_stack_p = !body->catch_except_p`.
+      #
+      # 3) If `body->catch_except_p` is false and `always_leaf?` of an insn is true,
+      # pc is not moved.
+      if body.catch_except_p
+        return false
+      end
+
+      pos = 0
+      while pos < body.iseq_size
+        insn = INSNS.fetch(C.rb_vm_insn_decode(body.iseq_encoded[pos]))
+        # All insns in the ISeq except `leave` (to be overridden in the inlined code)
+        # should meet following strong assumptions:
+        #   * Do not require `cfp->sp` motion
+        #   * Do not move `cfp->pc`
+        #   * Do not read any `cfp->pc`
+        if insn.name == :invokebuiltin || insn.name == :opt_invokebuiltin_delegate || insn.name == :opt_invokebuiltin_delegate_leave
+          # builtin insn's inlinability is handled by `Primitive.attr! 'inline'` per iseq
+          if !body.builtin_inline_p
+            return false;
+          end
+        elsif insn.name != :leave && C.insn_may_depend_on_sp_or_pc(insn.bin, body.iseq_encoded + (pos + 1))
+          return false
+        end
+        # At this moment, `cfp->ep` in an inlined method is not working.
+        case insn.name
+        when :getlocal,
+             :getlocal_WC_0,
+             :getlocal_WC_1,
+             :setlocal,
+             :setlocal_WC_0,
+             :setlocal_WC_1,
+             :getblockparam,
+             :getblockparamproxy,
+             :setblockparam
+          return false
+        end
+        pos += insn.len
+      end
+      return true
+    end
+
+    # CPointer::Struct could be nil on field reference, and this is a helper to
+    # handle that case while using CPointer::Struct#to_s in most cases.
+    # @param struct [RubyVM::MJIT::CPointer::Struct]
+    def to_addr(struct)
+      struct&.to_s || 'NULL'
+    end
+  end
+
+  private_constant(*constants)
+end