Revert "Revert "This commit implements the Object Shapes technique in CRuby.""

This reverts commit 9a6803c90b817f70389cae10d60b50ad752da48f.

4 files changed, 185 insertions, 2 deletions

diff --git a/test/-ext-/marshal/test_internal_ivar.rb b/test/-ext-/marshal/test_internal_ivar.rb
index a32138f6e8..9359c7f113 100644
--- a/test/-ext-/marshal/test_internal_ivar.rb
+++ b/test/-ext-/marshal/test_internal_ivar.rb
@@ -7,6 +7,7 @@ module Bug end
 module Bug::Marshal
   class TestInternalIVar < Test::Unit::TestCase
     def test_marshal
+      pend "We don't support IVs with ID of 0"
       v = InternalIVar.new("hello", "world", "bye")
       assert_equal("hello", v.normal)
       assert_equal("world", v.internal)
diff --git a/test/ruby/test_mjit.rb b/test/ruby/test_mjit.rb
index e49195f763..4c6cc6f39f 100644
--- a/test/ruby/test_mjit.rb
+++ b/test/ruby/test_mjit.rb
@@ -831,7 +831,7 @@ class TestMJIT < Test::Unit::TestCase
   end
 
   def test_inlined_exivar
-    assert_eval_with_jit("#{<<~"begin;"}\n#{<<~"end;"}", stdout: "aaa", success_count: 3, recompile_count: 1, min_calls: 2)
+    assert_eval_with_jit("#{<<~"begin;"}\n#{<<~"end;"}", stdout: "aaa", success_count: 4, recompile_count: 2, min_calls: 2)
     begin;
       class Foo < Hash
         def initialize
@@ -850,7 +850,7 @@ class TestMJIT < Test::Unit::TestCase
   end
 
   def test_inlined_undefined_ivar
-    assert_eval_with_jit("#{<<~"begin;"}\n#{<<~"end;"}", stdout: "bbb", success_count: 3, min_calls: 3)
+    assert_eval_with_jit("#{<<~"begin;"}\n#{<<~"end;"}", stdout: "bbb", success_count: 2, min_calls: 2)
     begin;
       class Foo
         def initialize
diff --git a/test/ruby/test_object.rb b/test/ruby/test_object.rb
index 83208bbcdb..a9d5d4b13e 100644
--- a/test/ruby/test_object.rb
+++ b/test/ruby/test_object.rb
@@ -993,4 +993,13 @@ class TestObject < Test::Unit::TestCase
       end
     EOS
   end
+
+  def test_frozen_inspect
+    obj = Object.new
+    obj.instance_variable_set(:@a, "a")
+    ins = obj.inspect
+    obj.freeze
+
+    assert_equal(ins, obj.inspect)
+  end
 end
diff --git a/test/ruby/test_shapes.rb b/test/ruby/test_shapes.rb
new file mode 100644
index 0000000000..807d485354
--- /dev/null
+++ b/test/ruby/test_shapes.rb
@@ -0,0 +1,173 @@
+# frozen_string_literal: false
+require 'test/unit'
+
+# These test the functionality of object shapes
+class TestShapes < Test::Unit::TestCase
+  class Example
+    def initialize
+      @a = 1
+    end
+  end
+
+  class RemoveAndAdd
+    def add_foo
+      @foo = 1
+    end
+
+    def remove
+      remove_instance_variable(:@foo)
+    end
+
+    def add_bar
+      @bar = 1
+    end
+  end
+
+  # RubyVM.debug_shape returns new instances of shape objects for
+  # each call. This helper method allows us to define equality for
+  # shapes
+  def assert_shape_equal(shape1, shape2)
+    assert_equal(shape1.id, shape2.id)
+    assert_equal(shape1.parent_id, shape2.parent_id)
+    assert_equal(shape1.depth, shape2.depth)
+    assert_equal(shape1.type, shape2.type)
+  end
+
+  def refute_shape_equal(shape1, shape2)
+    refute_equal(shape1.id, shape2.id)
+  end
+
+  def test_iv_index
+    example = RemoveAndAdd.new
+    shape = RubyVM.debug_shape(example)
+    assert_equal 0, shape.iv_count
+
+    example.add_foo # makes a transition
+    new_shape = RubyVM.debug_shape(example)
+    assert_equal([:@foo], example.instance_variables)
+    assert_equal(shape.id, new_shape.parent.id)
+    assert_equal(1, new_shape.iv_count)
+
+    example.remove # makes a transition
+    remove_shape = RubyVM.debug_shape(example)
+    assert_equal([], example.instance_variables)
+    assert_equal(new_shape.id, remove_shape.parent.id)
+    assert_equal(1, remove_shape.iv_count)
+
+    example.add_bar # makes a transition
+    bar_shape = RubyVM.debug_shape(example)
+    assert_equal([:@bar], example.instance_variables)
+    assert_equal(remove_shape.id, bar_shape.parent.id)
+    assert_equal(2, bar_shape.iv_count)
+  end
+
+  def test_new_obj_has_root_shape
+    assert_shape_equal(RubyVM.debug_root_shape, RubyVM.debug_shape(Object.new))
+  end
+
+  def test_frozen_new_obj_has_frozen_root_shape
+    assert_shape_equal(
+      RubyVM.debug_frozen_root_shape,
+      RubyVM.debug_shape(Object.new.freeze)
+    )
+  end
+
+  def test_str_has_root_shape
+    assert_shape_equal(RubyVM.debug_root_shape, RubyVM.debug_shape(""))
+  end
+
+  def test_array_has_root_shape
+    assert_shape_equal(RubyVM.debug_root_shape, RubyVM.debug_shape([]))
+  end
+
+  def test_hash_has_root_shape
+    assert_shape_equal(RubyVM.debug_root_shape, RubyVM.debug_shape({}))
+  end
+
+  def test_true_has_frozen_root_shape
+    assert_shape_equal(RubyVM.debug_frozen_root_shape, RubyVM.debug_shape(true))
+  end
+
+  def test_nil_has_frozen_root_shape
+    assert_shape_equal(RubyVM.debug_frozen_root_shape, RubyVM.debug_shape(nil))
+  end
+
+  def test_basic_shape_transition
+    obj = Example.new
+    refute_equal(RubyVM.debug_root_shape, RubyVM.debug_shape(obj))
+    assert_shape_equal(RubyVM.debug_root_shape.edges[:@a], RubyVM.debug_shape(obj))
+    assert_equal(obj.instance_variable_get(:@a), 1)
+  end
+
+  def test_different_objects_make_same_transition
+    obj = Example.new
+    obj2 = ""
+    obj2.instance_variable_set(:@a, 1)
+    assert_shape_equal(RubyVM.debug_shape(obj), RubyVM.debug_shape(obj2))
+  end
+
+  def test_duplicating_objects
+    obj = Example.new
+    obj2 = obj.dup
+    assert_shape_equal(RubyVM.debug_shape(obj), RubyVM.debug_shape(obj2))
+  end
+
+  def test_freezing_and_duplicating_object
+    obj = Object.new.freeze
+    obj2 = obj.dup
+    refute_predicate(obj2, :frozen?)
+    # dup'd objects shouldn't be frozen, and the shape should be the
+    # parent shape of the copied object
+    assert_equal(RubyVM.debug_shape(obj).parent.id, RubyVM.debug_shape(obj2).id)
+  end
+
+  def test_freezing_and_duplicating_object_with_ivars
+    obj = Example.new.freeze
+    obj2 = obj.dup
+    refute_predicate(obj2, :frozen?)
+    refute_shape_equal(RubyVM.debug_shape(obj), RubyVM.debug_shape(obj2))
+    assert_equal(obj2.instance_variable_get(:@a), 1)
+  end
+
+  def test_freezing_and_duplicating_string_with_ivars
+    str = "str"
+    str.instance_variable_set(:@a, 1)
+    str.freeze
+    str2 = str.dup
+    refute_predicate(str2, :frozen?)
+    refute_equal(RubyVM.debug_shape(str).id, RubyVM.debug_shape(str2).id)
+    assert_equal(str2.instance_variable_get(:@a), 1)
+  end
+
+  def test_freezing_and_cloning_objects
+    obj = Object.new.freeze
+    obj2 = obj.clone(freeze: true)
+    assert_predicate(obj2, :frozen?)
+    assert_shape_equal(RubyVM.debug_shape(obj), RubyVM.debug_shape(obj2))
+  end
+
+  def test_freezing_and_cloning_object_with_ivars
+    obj = Example.new.freeze
+    obj2 = obj.clone(freeze: true)
+    assert_predicate(obj2, :frozen?)
+    assert_shape_equal(RubyVM.debug_shape(obj), RubyVM.debug_shape(obj2))
+    assert_equal(obj2.instance_variable_get(:@a), 1)
+  end
+
+  def test_freezing_and_cloning_string
+    str = "str".freeze
+    str2 = str.clone(freeze: true)
+    assert_predicate(str2, :frozen?)
+    assert_shape_equal(RubyVM.debug_shape(str), RubyVM.debug_shape(str2))
+  end
+
+  def test_freezing_and_cloning_string_with_ivars
+    str = "str"
+    str.instance_variable_set(:@a, 1)
+    str.freeze
+    str2 = str.clone(freeze: true)
+    assert_predicate(str2, :frozen?)
+    assert_shape_equal(RubyVM.debug_shape(str), RubyVM.debug_shape(str2))
+    assert_equal(str2.instance_variable_get(:@a), 1)
+  end
+end