1 files changed, 394 insertions, 0 deletions
diff --git a/lib/ruby_vm/rjit/c_pointer.rb b/lib/ruby_vm/rjit/c_pointer.rb
new file mode 100644
index 0000000000..db00c4cd11
--- /dev/null
+++ b/lib/ruby_vm/rjit/c_pointer.rb
@@ -0,0 +1,394 @@
+module RubyVM::RJIT
+  # 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::RJIT::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 size [Integer]
+      # @param members [Hash{ Symbol => [Integer, RubyVM::RJIT::CType::*] }]
+      def self.define(size, members)
+        Class.new(self) do
+          # Return the size of this type
+          define_singleton_method(:size) { size }
+
+          # Return the offset to a field
+          define_singleton_method(:offsetof) do |field, *fields|
+            member, offset = members.fetch(field)
+            offset /= 8
+            unless fields.empty?
+              offset += member.offsetof(*fields)
+            end
+            offset
+          end
+
+          # Return member names
+          define_singleton_method(:members) { members.keys }
+
+          define_method(:initialize) do |addr = nil|
+            if addr.nil? # TODO: get rid of this feature later
+              addr = Fiddle.malloc(size)
+            end
+            super(addr, size, 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|
+              if to_ruby
+                value = C.to_value(value)
+              end
+              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::RJIT::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::RJIT::CType::* }]
+      def self.define(sizeof, members)
+        Class.new(self) do
+          # Return the size of this type
+          define_singleton_method(:sizeof) { sizeof }
+
+          # Part of Struct's offsetof implementation
+          define_singleton_method(:offsetof) do |field, *fields|
+            member = members.fetch(field)
+            offset = 0
+            unless fields.empty?
+              offset += member.offsetof(*fields)
+            end
+            offset
+          end
+
+          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
+
+    # Basically Immediate but without #* to skip auto-dereference of structs.
+    class Array
+      attr_reader :type
+
+      # @param addr [Integer]
+      # @param type [Class] RubyVM::RJIT::CType::*
+      def initialize(addr, type)
+        @addr = addr
+        @type = type
+      end
+
+      # Array access
+      def [](index)
+        @type.new(@addr)[index]
+      end
+
+      # Array set
+      # @param index [Integer]
+      # @param value [Integer, RubyVM::RJIT::CPointer::Struct] an address itself or an object that return an address with to_i
+      def []=(index, value)
+        @type.new(@addr)[index] = value
+      end
+
+      private
+
+      def self.define(block)
+        Class.new(self) do
+          define_method(:initialize) do |addr|
+            super(addr, block.call)
+          end
+        end
+      end
+    end
+
+    class Pointer
+      attr_reader :type
+
+      # @param addr [Integer]
+      # @param type [Class] RubyVM::RJIT::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::RJIT::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
+
+      # Get a raw address
+      def to_i
+        @addr
+      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::RJIT::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].unpack('c').first
+        if @width == 1
+          bit = (1 & (byte >> @offset))
+          bit == 1
+        elsif @width <= 8 && @offset == 0
+          bitmask = @width.times.map { |i| 1 << i }.sum
+          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.nil? && 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