From bb4cbd0803c3297ad036008adc7a01159ce44e1e Mon Sep 17 00:00:00 2001
From: Takashi Kokubun <takashikkbn@gmail.com>
Date: Wed, 21 Dec 2022 22:46:15 -0800
Subject: Put RubyVM::MJIT::Compiler under ruby_vm directory (#6989)

[Misc #19250]
---
 .gitignore                                         |   2 +-
 common.mk                                          |   6 +-
 lib/mjit/c_pointer.rb                              | 329 -------
 lib/mjit/c_type.rb                                 |  91 --
 lib/mjit/compiler.rb                               | 952 ---------------------
 lib/ruby_vm/mjit/c_pointer.rb                      | 329 +++++++
 lib/ruby_vm/mjit/c_type.rb                         |  91 ++
 lib/ruby_vm/mjit/compiler.rb                       | 952 +++++++++++++++++++++
 mjit.rb                                            |   8 +-
 tool/ruby_vm/views/lib/mjit/instruction.rb.erb     |  40 -
 .../views/lib/ruby_vm/mjit/instruction.rb.erb      |  40 +
 11 files changed, 1420 insertions(+), 1420 deletions(-)
 delete mode 100644 lib/mjit/c_pointer.rb
 delete mode 100644 lib/mjit/c_type.rb
 delete mode 100644 lib/mjit/compiler.rb
 create mode 100644 lib/ruby_vm/mjit/c_pointer.rb
 create mode 100644 lib/ruby_vm/mjit/c_type.rb
 create mode 100644 lib/ruby_vm/mjit/compiler.rb
 delete mode 100644 tool/ruby_vm/views/lib/mjit/instruction.rb.erb
 create mode 100644 tool/ruby_vm/views/lib/ruby_vm/mjit/instruction.rb.erb

diff --git a/.gitignore b/.gitignore
index 535c4fb789..99d32a1825 100644
--- a/.gitignore
+++ b/.gitignore
@@ -238,7 +238,7 @@ lcov*.info
 
 # MJIT
 /include/ruby-*/*/rb_mjit_min_header-*.h
-/lib/mjit/instruction.rb
+/lib/ruby_vm/mjit/instruction.rb
 /mjit_config.h
 /rb_mjit_header.h
 
diff --git a/common.mk b/common.mk
index 0d41d24947..8021f03a58 100644
--- a/common.mk
+++ b/common.mk
@@ -235,9 +235,9 @@ all: $(SHOWFLAGS) main docs
 main: $(SHOWFLAGS) exts $(ENCSTATIC:static=lib)encs
 	@$(NULLCMD)
 
-main: $(srcdir)/lib/mjit/instruction.rb
-srcs: $(srcdir)/lib/mjit/instruction.rb
-$(srcdir)/lib/mjit/instruction.rb: $(tooldir)/insns2vm.rb $(tooldir)/ruby_vm/views/lib/mjit/instruction.rb.erb $(srcdir)/insns.def
+main: $(srcdir)/lib/ruby_vm/mjit/instruction.rb
+srcs: $(srcdir)/lib/ruby_vm/mjit/instruction.rb
+$(srcdir)/lib/ruby_vm/mjit/instruction.rb: $(tooldir)/insns2vm.rb $(tooldir)/ruby_vm/views/lib/ruby_vm/mjit/instruction.rb.erb $(srcdir)/insns.def
 	$(ECHO) generating $@
 	$(Q) $(BASERUBY) -Ku $(tooldir)/insns2vm.rb --basedir="$(srcdir)" $(INSNS2VMOPT) $@
 
diff --git a/lib/mjit/c_pointer.rb b/lib/mjit/c_pointer.rb
deleted file mode 100644
index ee0be54a3c..0000000000
--- a/lib/mjit/c_pointer.rb
+++ /dev/null
@@ -1,329 +0,0 @@
-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
-    # 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 => [RubyVM::MJIT::CType::*, Integer, TrueClass] }]
-      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)
-        type, offset = @members.fetch(member)
-        type.new(@addr + offset / 8)
-      end
-
-      private
-
-      # @param member [Symbol]
-      # @param value [Object]
-      def []=(member, value)
-        type, offset = @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, (type, offset, 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 = Fiddle::PackInfo::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(Fiddle::PackInfo::PACK_MAP[Fiddle::TYPE_VOIDP])
-      end
-
-      private
-
-      def dest_addr
-        Fiddle::Pointer.new(@addr)[0, Fiddle::SIZEOF_VOIDP].unpack1(Fiddle::PackInfo::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(Fiddle::PackInfo::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 *
-        byte = Fiddle::Pointer.new(@addr)[0, Fiddle::SIZEOF_CHAR].unpack1('c')
-        if @width == 1
-          bit = (1 & (byte >> @offset))
-          bit == 1
-        elsif @width <= 8 && @offset == 0
-          bitmask = @width.times.sum { |i| 1 << i }
-          byte & bitmask
-        else
-          raise NotImplementedError.new("not-implemented bit field access: width=#{@width} offset=#{@offset}")
-        end
-      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
deleted file mode 100644
index 9e45d8d41c..0000000000
--- a/lib/mjit/c_type.rb
+++ /dev/null
@@ -1,91 +0,0 @@
-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]
-      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
-
-      # @param type [String]
-      def self.parse(ctype)
-        new(Fiddle::Importer.parse_ctype(ctype))
-      end
-
-      def self.find(size, signed)
-        fiddle_type = TYPE_MAP.fetch(size)
-        fiddle_type = -fiddle_type unless signed
-        new(fiddle_type)
-      end
-
-      TYPE_MAP = Fiddle::PackInfo::SIZE_MAP.map { |type, size| [size, type.abs] }.to_h
-      private_constant :TYPE_MAP
-    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
deleted file mode 100644
index fae51d6114..0000000000
--- a/lib/mjit/compiler.rb
+++ /dev/null
@@ -1,952 +0,0 @@
-# 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 RubyVM::MJIT::Compiler
-  C = RubyVM::MJIT.const_get(:C, false)
-  INSNS = RubyVM::MJIT.const_get(:INSNS, false)
-  UNSUPPORTED_INSNS = [
-    :defineclass, # low priority
-  ]
-
-  def initialize = freeze
-
-  # @param iseq [RubyVM::MJIT::CPointer::Struct]
-  # @param funcname [String]
-  # @param id [Integer]
-  # @return [String,NilClass]
-  def compile(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 nil
-    end
-
-    src = +''
-    if !status.compile_info.disable_send_cache && !status.compile_info.disable_inlining
-      unless precompile_inlinable_iseqs(src, iseq, status)
-        return nil
-      end
-    end
-
-    src << "VALUE\n#{funcname}(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp)\n{\n"
-    success = compile_body(src, iseq, status)
-    src << "\n} // end of #{funcname}\n"
-
-    return success ? src : nil
-  rescue Exception => e # should we use rb_rescue in C instead?
-    if C.mjit_opts.warnings || C.mjit_opts.verbose > 0
-      $stderr.puts "MJIT error: #{e.full_message}"
-    end
-    return nil
-  end
-
-  private
-
-  def compile_body(src, 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"
-
-    # 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
-
-    # Generate merged ivar guards first if needed
-    if !status.compile_info.disable_ivar_cache && using_ivar?(iseq.body)
-      src << "    if (UNLIKELY(!RB_TYPE_P(GET_SELF(), T_OBJECT))) {"
-      src << "        goto ivar_cancel;\n"
-      src << "    }\n"
-    end
-
-    compile_insns(0, 0, status, iseq.body, src)
-    compile_cancel_handler(src, iseq.body, status)
-    src << "#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, src)
-    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
-
-      src << "\nlabel_#{pos}: /* #{insn.name} */\n"
-      pos = compile_insn(insn, pos, status, body.iseq_encoded + (pos+1), body, branch, src)
-      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, src)
-    sp_inc = C.mjit_call_attribute_sp_inc(insn.bin, operands)
-    next_pos = pos + insn.len
-
-    result = compile_insn_entry(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
-      result_src, next_pos, finish_p, compile_insns_p = result
-
-      src << result_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)
-          src << "goto label_#{pos + insn.len};\n"
-        else
-          compile_insns(b.stack_size, pos + insn.len, status, body, src)
-        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)
-      src << "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
-
-  def compile_insn_entry(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 :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 :invokebuiltin, :opt_invokebuiltin_delegate, :opt_invokebuiltin_delegate_leave
-      if src = compile_invokebuiltin(insn, stack_size, sp_inc, body, operands)
-        if insn.name == :opt_invokebuiltin_delegate_leave
-          src << compile_leave(stack_size, pos, inlined_iseq_p)
-          finish_p = true
-        end
-        return src, next_pos, finish_p, compile_insns
-      end
-    when :leave
-      if stack_size != 1
-        raise "Unexpected JIT stack_size on leave: #{stack_size}"
-      end
-      src = compile_leave(stack_size, pos, inlined_iseq_p)
-      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)
-  end
-
-  # Optimized case of send / opt_send_without_block instructions.
-  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 << "        goto cancel;\n"
-        src << "    }\n"
-      end
-
-      src << "}\n"
-      return src
-    else
-      return nil
-    end
-  end
-
-  def compile_ivar(insn_name, stack_size, pos, status, operands, body)
-    iv_cache = C.iseq_inline_storage_entry.new(operands[1]).iv_cache
-    dest_shape_id = iv_cache.value >> C.SHAPE_FLAG_SHIFT
-    source_shape_id = parent_shape_id(dest_shape_id)
-    attr_index = iv_cache.value & ((1 << C.SHAPE_FLAG_SHIFT) - 1)
-
-    src = +''
-    if !status.compile_info.disable_ivar_cache && source_shape_id != C.INVALID_SHAPE_ID
-      # 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" # T_OBJECT guaranteed by compile_body
-      # JIT: cache hit path of vm_getivar/vm_setivar, or cancel JIT (recompile it with exivar)
-      if insn_name == :setinstancevariable
-        src << "    const uint32_t index = #{attr_index - 1};\n"
-        src << "    const shape_id_t dest_shape_id = (shape_id_t)#{dest_shape_id};\n"
-        src << "    if (dest_shape_id == ROBJECT_SHAPE_ID(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 << "    const shape_id_t source_shape_id = (shape_id_t)#{dest_shape_id};\n"
-        if attr_index == 0 # cache hit, but uninitialized iv
-          src << "    /* Uninitialized instance variable */\n"
-          src << "    if (source_shape_id == ROBJECT_SHAPE_ID(obj)) {\n"
-          src << "        stack[#{stack_size}] = Qnil;\n"
-          src << "    }\n"
-        else
-          src << "    const uint32_t index = #{attr_index - 1};\n"
-          src << "    if (source_shape_id == ROBJECT_SHAPE_ID(obj)) {\n"
-          src << "        stack[#{stack_size}] = ROBJECT_IVPTR(obj)[index];\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 && source_shape_id != C.INVALID_SHAPE_ID
-      # 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 shape_id_t source_shape_id = (shape_id_t)#{dest_shape_id};\n"
-      src << "    const uint32_t index = #{attr_index - 1};\n"
-      # JIT: cache hit path of vm_getivar, or cancel JIT (recompile it without any ivar optimization)
-      src << "    struct gen_ivtbl *ivtbl;\n"
-      src << "    if (LIKELY(FL_TEST_RAW(GET_SELF(), FL_EXIVAR) && source_shape_id == rb_shape_get_shape_id(obj) && rb_ivar_generic_ivtbl_lookup(obj, &ivtbl))) {\n"
-      src << "        stack[#{stack_size}] = ivtbl->ivptr[index];\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
-
-  def compile_invokebuiltin(insn, stack_size, sp_inc, body, operands)
-    bf = C.RB_BUILTIN.new(operands[0])
-    if bf.compiler > 0
-      index = (insn.name == :invokebuiltin ? -1 : operands[1])
-      src = +"{\n"
-      src << "    VALUE val;\n"
-      C.builtin_compiler(src, bf, index, stack_size, body.builtin_inline_p)
-      src << "    stack[#{stack_size + sp_inc - 1}] = val;\n"
-      src << "}\n"
-      return src
-    else
-      return nil
-    end
-  end
-
-  def compile_leave(stack_size, pos, inlined_iseq_p)
-    src = +''
-    # 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"
-  end
-
-  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
-
-  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 << "        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
-
-  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 << "                    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
-          hash_offsets = C.rb_hash_values(operands[0])
-          else_offset = cast_offset(operands[1])
-          base_pos = pos + insn_len
-
-          src << "    switch (#{dest}) {\n"
-          hash_offsets.each do |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 << "            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
-
-  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(src, body, inline_context)
-    src << "\ncancel:\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"
-  end
-
-  # Print the block to cancel JIT execution.
-  def compile_cancel_handler(src, body, status)
-    if status.inlined_iseqs.nil? # the current ISeq is being inlined
-      compile_inlined_cancel_handler(src, body, status.inline_context)
-      return
-    end
-
-    src << "\nsend_cancel:\n"
-    src << "    rb_mjit_recompile_send(original_iseq);\n"
-    src << "    goto cancel;\n"
-
-    src << "\nivar_cancel:\n"
-    src << "    rb_mjit_recompile_ivar(original_iseq);\n"
-    src << "    goto cancel;\n"
-
-    src << "\nexivar_cancel:\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"
-    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"
-  end
-
-  def precompile_inlinable_child_iseq(src, 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
-
-    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"
-
-    success = compile_body(src, child_iseq, child_status)
-
-    src << "\n} /* end of _mjit#{status.compiled_id}_inlined_#{pos} */\n\n"
-
-    return success;
-  end
-
-  def precompile_inlinable_iseqs(src, 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)}:#{C.rb_iseq_first_lineno(child_iseq)} " \
-              "=> #{iseq.body.location.label}@#{C.rb_iseq_path(iseq)}:#{C.rb_iseq_first_lineno(iseq)}"
-          end
-          if !precompile_inlinable_child_iseq(src, 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 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 using_ivar?(body)
-    pos = 0
-    while pos < body.iseq_size
-      insn = INSNS.fetch(C.rb_vm_insn_decode(body.iseq_encoded[pos]))
-      case insn.name
-      when :getinstancevariable, :setinstancevariable
-        return true
-      end
-      pos += insn.len
-    end
-    return false
-  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)
-    if offset >= 1 << 8 * Fiddle::SIZEOF_VOIDP - 1 # negative
-      offset -= 1 << 8 * Fiddle::SIZEOF_VOIDP
-    end
-    offset
-  end
-
-  def captured_cc_entries(status)
-    status.compiled_iseq.mjit_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.mjit_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
-
-  def parent_shape_id(shape_id)
-    return shape_id if shape_id == C.INVALID_SHAPE_ID
-
-    parent_id = C.rb_shape_get_shape_by_id(shape_id).parent_id
-    parent = C.rb_shape_get_shape_by_id(parent_id)
-
-    if parent.type == C.SHAPE_CAPACITY_CHANGE
-      parent.parent_id
-    else
-      parent_id
-    end
-  end
-end
diff --git a/lib/ruby_vm/mjit/c_pointer.rb b/lib/ruby_vm/mjit/c_pointer.rb
new file mode 100644
index 0000000000..ee0be54a3c
--- /dev/null
+++ b/lib/ruby_vm/mjit/c_pointer.rb
@@ -0,0 +1,329 @@
+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
+    # 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 => [RubyVM::MJIT::CType::*, Integer, TrueClass] }]
+      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)
+        type, offset = @members.fetch(member)
+        type.new(@addr + offset / 8)
+      end
+
+      private
+
+      # @param member [Symbol]
+      # @param value [Object]
+      def []=(member, value)
+        type, offset = @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, (type, offset, 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 = Fiddle::PackInfo::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(Fiddle::PackInfo::PACK_MAP[Fiddle::TYPE_VOIDP])
+      end
+
+      private
+
+      def dest_addr
+        Fiddle::Pointer.new(@addr)[0, Fiddle::SIZEOF_VOIDP].unpack1(Fiddle::PackInfo::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(Fiddle::PackInfo::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 *
+        byte = Fiddle::Pointer.new(@addr)[0, Fiddle::SIZEOF_CHAR].unpack1('c')
+        if @width == 1
+          bit = (1 & (byte >> @offset))
+          bit == 1
+        elsif @width <= 8 && @offset == 0
+          bitmask = @width.times.sum { |i| 1 << i }
+          byte & bitmask
+        else
+          raise NotImplementedError.new("not-implemented bit field access: width=#{@width} offset=#{@offset}")
+        end
+      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/ruby_vm/mjit/c_type.rb b/lib/ruby_vm/mjit/c_type.rb
new file mode 100644
index 0000000000..9e45d8d41c
--- /dev/null
+++ b/lib/ruby_vm/mjit/c_type.rb
@@ -0,0 +1,91 @@
+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]
+      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
+
+      # @param type [String]
+      def self.parse(ctype)
+        new(Fiddle::Importer.parse_ctype(ctype))
+      end
+
+      def self.find(size, signed)
+        fiddle_type = TYPE_MAP.fetch(size)
+        fiddle_type = -fiddle_type unless signed
+        new(fiddle_type)
+      end
+
+      TYPE_MAP = Fiddle::PackInfo::SIZE_MAP.map { |type, size| [size, type.abs] }.to_h
+      private_constant :TYPE_MAP
+    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/ruby_vm/mjit/compiler.rb b/lib/ruby_vm/mjit/compiler.rb
new file mode 100644
index 0000000000..fae51d6114
--- /dev/null
+++ b/lib/ruby_vm/mjit/compiler.rb
@@ -0,0 +1,952 @@
+# 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 RubyVM::MJIT::Compiler
+  C = RubyVM::MJIT.const_get(:C, false)
+  INSNS = RubyVM::MJIT.const_get(:INSNS, false)
+  UNSUPPORTED_INSNS = [
+    :defineclass, # low priority
+  ]
+
+  def initialize = freeze
+
+  # @param iseq [RubyVM::MJIT::CPointer::Struct]
+  # @param funcname [String]
+  # @param id [Integer]
+  # @return [String,NilClass]
+  def compile(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 nil
+    end
+
+    src = +''
+    if !status.compile_info.disable_send_cache && !status.compile_info.disable_inlining
+      unless precompile_inlinable_iseqs(src, iseq, status)
+        return nil
+      end
+    end
+
+    src << "VALUE\n#{funcname}(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp)\n{\n"
+    success = compile_body(src, iseq, status)
+    src << "\n} // end of #{funcname}\n"
+
+    return success ? src : nil
+  rescue Exception => e # should we use rb_rescue in C instead?
+    if C.mjit_opts.warnings || C.mjit_opts.verbose > 0
+      $stderr.puts "MJIT error: #{e.full_message}"
+    end
+    return nil
+  end
+
+  private
+
+  def compile_body(src, 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"
+
+    # 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
+
+    # Generate merged ivar guards first if needed
+    if !status.compile_info.disable_ivar_cache && using_ivar?(iseq.body)
+      src << "    if (UNLIKELY(!RB_TYPE_P(GET_SELF(), T_OBJECT))) {"
+      src << "        goto ivar_cancel;\n"
+      src << "    }\n"
+    end
+
+    compile_insns(0, 0, status, iseq.body, src)
+    compile_cancel_handler(src, iseq.body, status)
+    src << "#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, src)
+    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
+
+      src << "\nlabel_#{pos}: /* #{insn.name} */\n"
+      pos = compile_insn(insn, pos, status, body.iseq_encoded + (pos+1), body, branch, src)
+      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, src)
+    sp_inc = C.mjit_call_attribute_sp_inc(insn.bin, operands)
+    next_pos = pos + insn.len
+
+    result = compile_insn_entry(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
+      result_src, next_pos, finish_p, compile_insns_p = result
+
+      src << result_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)
+          src << "goto label_#{pos + insn.len};\n"
+        else
+          compile_insns(b.stack_size, pos + insn.len, status, body, src)
+        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)
+      src << "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
+
+  def compile_insn_entry(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 :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 :invokebuiltin, :opt_invokebuiltin_delegate, :opt_invokebuiltin_delegate_leave
+      if src = compile_invokebuiltin(insn, stack_size, sp_inc, body, operands)
+        if insn.name == :opt_invokebuiltin_delegate_leave
+          src << compile_leave(stack_size, pos, inlined_iseq_p)
+          finish_p = true
+        end
+        return src, next_pos, finish_p, compile_insns
+      end
+    when :leave
+      if stack_size != 1
+        raise "Unexpected JIT stack_size on leave: #{stack_size}"
+      end
+      src = compile_leave(stack_size, pos, inlined_iseq_p)
+      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)
+  end
+
+  # Optimized case of send / opt_send_without_block instructions.
+  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 << "        goto cancel;\n"
+        src << "    }\n"
+      end
+
+      src << "}\n"
+      return src
+    else
+      return nil
+    end
+  end
+
+  def compile_ivar(insn_name, stack_size, pos, status, operands, body)
+    iv_cache = C.iseq_inline_storage_entry.new(operands[1]).iv_cache
+    dest_shape_id = iv_cache.value >> C.SHAPE_FLAG_SHIFT
+    source_shape_id = parent_shape_id(dest_shape_id)
+    attr_index = iv_cache.value & ((1 << C.SHAPE_FLAG_SHIFT) - 1)
+
+    src = +''
+    if !status.compile_info.disable_ivar_cache && source_shape_id != C.INVALID_SHAPE_ID
+      # 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" # T_OBJECT guaranteed by compile_body
+      # JIT: cache hit path of vm_getivar/vm_setivar, or cancel JIT (recompile it with exivar)
+      if insn_name == :setinstancevariable
+        src << "    const uint32_t index = #{attr_index - 1};\n"
+        src << "    const shape_id_t dest_shape_id = (shape_id_t)#{dest_shape_id};\n"
+        src << "    if (dest_shape_id == ROBJECT_SHAPE_ID(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 << "    const shape_id_t source_shape_id = (shape_id_t)#{dest_shape_id};\n"
+        if attr_index == 0 # cache hit, but uninitialized iv
+          src << "    /* Uninitialized instance variable */\n"
+          src << "    if (source_shape_id == ROBJECT_SHAPE_ID(obj)) {\n"
+          src << "        stack[#{stack_size}] = Qnil;\n"
+          src << "    }\n"
+        else
+          src << "    const uint32_t index = #{attr_index - 1};\n"
+          src << "    if (source_shape_id == ROBJECT_SHAPE_ID(obj)) {\n"
+          src << "        stack[#{stack_size}] = ROBJECT_IVPTR(obj)[index];\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 && source_shape_id != C.INVALID_SHAPE_ID
+      # 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 shape_id_t source_shape_id = (shape_id_t)#{dest_shape_id};\n"
+      src << "    const uint32_t index = #{attr_index - 1};\n"
+      # JIT: cache hit path of vm_getivar, or cancel JIT (recompile it without any ivar optimization)
+      src << "    struct gen_ivtbl *ivtbl;\n"
+      src << "    if (LIKELY(FL_TEST_RAW(GET_SELF(), FL_EXIVAR) && source_shape_id == rb_shape_get_shape_id(obj) && rb_ivar_generic_ivtbl_lookup(obj, &ivtbl))) {\n"
+      src << "        stack[#{stack_size}] = ivtbl->ivptr[index];\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
+
+  def compile_invokebuiltin(insn, stack_size, sp_inc, body, operands)
+    bf = C.RB_BUILTIN.new(operands[0])
+    if bf.compiler > 0
+      index = (insn.name == :invokebuiltin ? -1 : operands[1])
+      src = +"{\n"
+      src << "    VALUE val;\n"
+      C.builtin_compiler(src, bf, index, stack_size, body.builtin_inline_p)
+      src << "    stack[#{stack_size + sp_inc - 1}] = val;\n"
+      src << "}\n"
+      return src
+    else
+      return nil
+    end
+  end
+
+  def compile_leave(stack_size, pos, inlined_iseq_p)
+    src = +''
+    # 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"
+  end
+
+  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
+
+  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 << "        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
+
+  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 << "                    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
+          hash_offsets = C.rb_hash_values(operands[0])
+          else_offset = cast_offset(operands[1])
+          base_pos = pos + insn_len
+
+          src << "    switch (#{dest}) {\n"
+          hash_offsets.each do |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 << "            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
+
+  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(src, body, inline_context)
+    src << "\ncancel:\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"
+  end
+
+  # Print the block to cancel JIT execution.
+  def compile_cancel_handler(src, body, status)
+    if status.inlined_iseqs.nil? # the current ISeq is being inlined
+      compile_inlined_cancel_handler(src, body, status.inline_context)
+      return
+    end
+
+    src << "\nsend_cancel:\n"
+    src << "    rb_mjit_recompile_send(original_iseq);\n"
+    src << "    goto cancel;\n"
+
+    src << "\nivar_cancel:\n"
+    src << "    rb_mjit_recompile_ivar(original_iseq);\n"
+    src << "    goto cancel;\n"
+
+    src << "\nexivar_cancel:\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"
+    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"
+  end
+
+  def precompile_inlinable_child_iseq(src, 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
+
+    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"
+
+    success = compile_body(src, child_iseq, child_status)
+
+    src << "\n} /* end of _mjit#{status.compiled_id}_inlined_#{pos} */\n\n"
+
+    return success;
+  end
+
+  def precompile_inlinable_iseqs(src, 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)}:#{C.rb_iseq_first_lineno(child_iseq)} " \
+              "=> #{iseq.body.location.label}@#{C.rb_iseq_path(iseq)}:#{C.rb_iseq_first_lineno(iseq)}"
+          end
+          if !precompile_inlinable_child_iseq(src, 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 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 using_ivar?(body)
+    pos = 0
+    while pos < body.iseq_size
+      insn = INSNS.fetch(C.rb_vm_insn_decode(body.iseq_encoded[pos]))
+      case insn.name
+      when :getinstancevariable, :setinstancevariable
+        return true
+      end
+      pos += insn.len
+    end
+    return false
+  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)
+    if offset >= 1 << 8 * Fiddle::SIZEOF_VOIDP - 1 # negative
+      offset -= 1 << 8 * Fiddle::SIZEOF_VOIDP
+    end
+    offset
+  end
+
+  def captured_cc_entries(status)
+    status.compiled_iseq.mjit_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.mjit_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
+
+  def parent_shape_id(shape_id)
+    return shape_id if shape_id == C.INVALID_SHAPE_ID
+
+    parent_id = C.rb_shape_get_shape_by_id(shape_id).parent_id
+    parent = C.rb_shape_get_shape_by_id(parent_id)
+
+    if parent.type == C.SHAPE_CAPACITY_CHANGE
+      parent.parent_id
+    else
+      parent_id
+    end
+  end
+end
diff --git a/mjit.rb b/mjit.rb
index 64c1c69c1a..7391451a6c 100644
--- a/mjit.rb
+++ b/mjit.rb
@@ -20,10 +20,10 @@ if RubyVM::MJIT.enabled?
     return # miniruby doesn't support MJIT
   end
 
-  RubyVM::MJIT::C = Object.new # forward declaration for mjit/compiler
-  require "mjit/c_type"
-  require "mjit/instruction"
-  require "mjit/compiler"
+  RubyVM::MJIT::C = Object.new # forward declaration for ruby_vm/mjit/compiler
+  require 'ruby_vm/mjit/c_type'
+  require 'ruby_vm/mjit/instruction'
+  require 'ruby_vm/mjit/compiler'
 
   module RubyVM::MJIT
     private_constant(*constants)
diff --git a/tool/ruby_vm/views/lib/mjit/instruction.rb.erb b/tool/ruby_vm/views/lib/mjit/instruction.rb.erb
deleted file mode 100644
index dac53668a0..0000000000
--- a/tool/ruby_vm/views/lib/mjit/instruction.rb.erb
+++ /dev/null
@@ -1,40 +0,0 @@
-module RubyVM::MJIT
-  Instruction = Struct.new(
-    :name,
-    :bin,
-    :len,
-    :expr,
-    :declarations,
-    :preamble,
-    :opes,
-    :pops,
-    :rets,
-    :always_leaf?,
-    :leaf_without_check_ints?,
-    :handles_sp?,
-  )
-
-  INSNS = {
-% RubyVM::Instructions.each_with_index do |insn, i|
-%   next if insn.name.start_with?('trace_')
-    <%= i %> => Instruction.new(
-      name: :<%= insn.name %>,
-      bin: <%= i %>, # BIN(<%= insn.name %>)
-      len: <%= insn.width %>, # insn_len
-      expr: <<-EXPR,
-<%= insn.expr.expr.dump.sub(/\A"/, '').sub(/"\z/, '').gsub(/\\n/, "\n").gsub(/\\t/, ' ' * 8) %>
-      EXPR
-      declarations: <%= insn.declarations.inspect %>,
-      preamble: <%= insn.preamble.map(&:expr).inspect %>,
-      opes: <%= insn.opes.inspect %>,
-      pops: <%= insn.pops.inspect %>,
-      rets: <%= insn.rets.inspect %>,
-      always_leaf?: <%= insn.always_leaf? %>,
-      leaf_without_check_ints?: <%= insn.leaf_without_check_ints? %>,
-      handles_sp?: <%= insn.handles_sp? %>,
-    ),
-% end
-  }
-
-  private_constant(*constants)
-end
diff --git a/tool/ruby_vm/views/lib/ruby_vm/mjit/instruction.rb.erb b/tool/ruby_vm/views/lib/ruby_vm/mjit/instruction.rb.erb
new file mode 100644
index 0000000000..dac53668a0
--- /dev/null
+++ b/tool/ruby_vm/views/lib/ruby_vm/mjit/instruction.rb.erb
@@ -0,0 +1,40 @@
+module RubyVM::MJIT
+  Instruction = Struct.new(
+    :name,
+    :bin,
+    :len,
+    :expr,
+    :declarations,
+    :preamble,
+    :opes,
+    :pops,
+    :rets,
+    :always_leaf?,
+    :leaf_without_check_ints?,
+    :handles_sp?,
+  )
+
+  INSNS = {
+% RubyVM::Instructions.each_with_index do |insn, i|
+%   next if insn.name.start_with?('trace_')
+    <%= i %> => Instruction.new(
+      name: :<%= insn.name %>,
+      bin: <%= i %>, # BIN(<%= insn.name %>)
+      len: <%= insn.width %>, # insn_len
+      expr: <<-EXPR,
+<%= insn.expr.expr.dump.sub(/\A"/, '').sub(/"\z/, '').gsub(/\\n/, "\n").gsub(/\\t/, ' ' * 8) %>
+      EXPR
+      declarations: <%= insn.declarations.inspect %>,
+      preamble: <%= insn.preamble.map(&:expr).inspect %>,
+      opes: <%= insn.opes.inspect %>,
+      pops: <%= insn.pops.inspect %>,
+      rets: <%= insn.rets.inspect %>,
+      always_leaf?: <%= insn.always_leaf? %>,
+      leaf_without_check_ints?: <%= insn.leaf_without_check_ints? %>,
+      handles_sp?: <%= insn.handles_sp? %>,
+    ),
+% end
+  }
+
+  private_constant(*constants)
+end
-- 
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