Move object_id in object fields.

And get rid of the `obj_to_id_tbl`

It's no longer needed, the `object_id` is now stored inline
in the object alongside instance variables.

We still need the inverse table in case `_id2ref` is invoked, but
we lazily build it by walking the heap if that happens.

The `object_id` concern is also no longer a GC implementation
concern, but a generic implementation.

Co-Authored-By: Matt Valentine-House <matt@eightbitraptor.com>

test/ruby/test_object_id.rb

@@ -0,0 +1,177 @@
+require 'test/unit'
+
+class TestObjectId < Test::Unit::TestCase
+  def setup
+    @obj = Object.new
+  end
+
+  def test_dup_new_id
+    id = @obj.object_id
+    refute_equal id, @obj.dup.object_id
+  end
+
+  def test_dup_with_ivar_and_id
+    id = @obj.object_id
+    @obj.instance_variable_set(:@foo, 42)
+
+    copy = @obj.dup
+    refute_equal id, copy.object_id
+    assert_equal 42, copy.instance_variable_get(:@foo)
+  end
+
+  def test_dup_with_id_and_ivar
+    @obj.instance_variable_set(:@foo, 42)
+    id = @obj.object_id
+
+    copy = @obj.dup
+    refute_equal id, copy.object_id
+    assert_equal 42, copy.instance_variable_get(:@foo)
+  end
+
+  def test_dup_with_id_and_ivar_and_frozen
+    @obj.instance_variable_set(:@foo, 42)
+    @obj.freeze
+    id = @obj.object_id
+
+    copy = @obj.dup
+    refute_equal id, copy.object_id
+    assert_equal 42, copy.instance_variable_get(:@foo)
+    refute_predicate copy, :frozen?
+  end
+
+  def test_clone_new_id
+    id = @obj.object_id
+    refute_equal id, @obj.clone.object_id
+  end
+
+  def test_clone_with_ivar_and_id
+    id = @obj.object_id
+    @obj.instance_variable_set(:@foo, 42)
+
+    copy = @obj.clone
+    refute_equal id, copy.object_id
+    assert_equal 42, copy.instance_variable_get(:@foo)
+  end
+
+  def test_clone_with_id_and_ivar
+    @obj.instance_variable_set(:@foo, 42)
+    id = @obj.object_id
+
+    copy = @obj.clone
+    refute_equal id, copy.object_id
+    assert_equal 42, copy.instance_variable_get(:@foo)
+  end
+
+  def test_clone_with_id_and_ivar_and_frozen
+    @obj.instance_variable_set(:@foo, 42)
+    @obj.freeze
+    id = @obj.object_id
+
+    copy = @obj.clone
+    refute_equal id, copy.object_id
+    assert_equal 42, copy.instance_variable_get(:@foo)
+    assert_predicate copy, :frozen?
+  end
+
+  def test_marshal_new_id
+    return pass if @obj.is_a?(Module)
+
+    id = @obj.object_id
+    refute_equal id, Marshal.load(Marshal.dump(@obj)).object_id
+  end
+
+  def test_marshal_with_ivar_and_id
+    return pass if @obj.is_a?(Module)
+
+    id = @obj.object_id
+    @obj.instance_variable_set(:@foo, 42)
+
+    copy = Marshal.load(Marshal.dump(@obj))
+    refute_equal id, copy.object_id
+    assert_equal 42, copy.instance_variable_get(:@foo)
+  end
+
+  def test_marshal_with_id_and_ivar
+    return pass if @obj.is_a?(Module)
+
+    @obj.instance_variable_set(:@foo, 42)
+    id = @obj.object_id
+
+    copy = Marshal.load(Marshal.dump(@obj))
+    refute_equal id, copy.object_id
+    assert_equal 42, copy.instance_variable_get(:@foo)
+  end
+
+  def test_marshal_with_id_and_ivar_and_frozen
+    return pass if @obj.is_a?(Module)
+
+    @obj.instance_variable_set(:@foo, 42)
+    @obj.freeze
+    id = @obj.object_id
+
+    copy = Marshal.load(Marshal.dump(@obj))
+    refute_equal id, copy.object_id
+    assert_equal 42, copy.instance_variable_get(:@foo)
+    refute_predicate copy, :frozen?
+  end
+end
+
+class TestObjectIdClass < TestObjectId
+  def setup
+    @obj = Class.new
+  end
+end
+
+class TestObjectIdGeneric < TestObjectId
+  def setup
+    @obj = Array.new
+  end
+end
+
+class TestObjectIdTooComplex < TestObjectId
+  class TooComplex
+  end
+
+  def setup
+    if defined?(RubyVM::Shape::SHAPE_MAX_VARIATIONS)
+      assert_equal 8, RubyVM::Shape::SHAPE_MAX_VARIATIONS
+    end
+    8.times do |i|
+      TooComplex.new.instance_variable_set("@a#{i}", 1)
+    end
+    @obj = TooComplex.new
+    @obj.instance_variable_set(:@test, 1)
+  end
+end
+
+class TestObjectIdTooComplexClass < TestObjectId
+  class TooComplex < Module
+  end
+
+  def setup
+    if defined?(RubyVM::Shape::SHAPE_MAX_VARIATIONS)
+      assert_equal 8, RubyVM::Shape::SHAPE_MAX_VARIATIONS
+    end
+    8.times do |i|
+      TooComplex.new.instance_variable_set("@a#{i}", 1)
+    end
+    @obj = TooComplex.new
+    @obj.instance_variable_set(:@test, 1)
+  end
+end
+
+class TestObjectIdTooComplexGeneric < TestObjectId
+  class TooComplex < Array
+  end
+
+  def setup
+    if defined?(RubyVM::Shape::SHAPE_MAX_VARIATIONS)
+      assert_equal 8, RubyVM::Shape::SHAPE_MAX_VARIATIONS
+    end
+    8.times do |i|
+      TooComplex.new.instance_variable_set("@a#{i}", 1)
+    end
+    @obj = TooComplex.new
+    @obj.instance_variable_set(:@test, 1)
+  end
+end

test/ruby/test_shapes.rb

@@ -622,6 +622,73 @@ class TestShapes < Test::Unit::TestCase
     end;
   end
 
+  def test_too_complex_and_frozen
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
+    begin;
+      $VERBOSE = nil
+      class TooComplex
+        attr_reader :very_unique
+      end
+
+      RubyVM::Shape::SHAPE_MAX_VARIATIONS.times do
+        TooComplex.new.instance_variable_set(:"@unique_#{_1}", Object.new)
+      end
+
+      tc = TooComplex.new
+      tc.instance_variable_set(:"@very_unique", 3)
+
+      shape = RubyVM::Shape.of(tc)
+      assert_predicate shape, :too_complex?
+      refute_predicate shape, :shape_frozen?
+      tc.freeze
+      frozen_shape = RubyVM::Shape.of(tc)
+      refute_equal shape.id, frozen_shape.id
+      assert_predicate frozen_shape, :too_complex?
+      assert_predicate frozen_shape, :shape_frozen?
+
+      assert_equal 3, tc.very_unique
+      assert_equal 3, Ractor.make_shareable(tc).very_unique
+    end;
+  end
+
+  def test_too_complex_and_frozen_and_object_id
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
+    begin;
+      $VERBOSE = nil
+      class TooComplex
+        attr_reader :very_unique
+      end
+
+      RubyVM::Shape::SHAPE_MAX_VARIATIONS.times do
+        TooComplex.new.instance_variable_set(:"@unique_#{_1}", Object.new)
+      end
+
+      tc = TooComplex.new
+      tc.instance_variable_set(:"@very_unique", 3)
+
+      shape = RubyVM::Shape.of(tc)
+      assert_predicate shape, :too_complex?
+      refute_predicate shape, :shape_frozen?
+      tc.freeze
+      frozen_shape = RubyVM::Shape.of(tc)
+      refute_equal shape.id, frozen_shape.id
+      assert_predicate frozen_shape, :too_complex?
+      assert_predicate frozen_shape, :shape_frozen?
+      refute_predicate frozen_shape, :has_object_id?
+
+      tc.object_id
+
+      id_shape = RubyVM::Shape.of(tc)
+      refute_equal frozen_shape.id, id_shape.id
+      assert_predicate id_shape, :too_complex?
+      assert_predicate id_shape, :shape_frozen?
+      assert_predicate id_shape, :has_object_id?
+
+      assert_equal 3, tc.very_unique
+      assert_equal 3, Ractor.make_shareable(tc).very_unique
+    end;
+  end
+
   def test_too_complex_obj_ivar_ractor_share
     assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
     begin;