Re-embed when removing Object instance variables

Objects with the same shape must always have the same "embeddedness"
(either embedded or heap allocated) because YJIT assumes so. However,
using remove_instance_variable, it's possible that some objects are
embedded and some are heap allocated because it does not re-embed heap
allocated objects.

This commit changes remove_instance_variable to re-embed Object
instance variables when it becomes small enough.

1 files changed, 35 insertions, 0 deletions

diff --git a/test/ruby/test_object.rb b/test/ruby/test_object.rb
index 3c5b6424ba..acc913b9c0 100644
--- a/test/ruby/test_object.rb
+++ b/test/ruby/test_object.rb
@@ -355,6 +355,41 @@ class TestObject < Test::Unit::TestCase
     end
   end
 
+  def test_remove_instance_variable_re_embed
+    require "objspace"
+
+    c = Class.new do
+      def a = @a
+
+      def b = @b
+
+      def c = @c
+    end
+
+    o1 = c.new
+    o2 = c.new
+
+    o1.instance_variable_set(:@foo, 5)
+    o1.instance_variable_set(:@a, 0)
+    o1.instance_variable_set(:@b, 1)
+    o1.instance_variable_set(:@c, 2)
+    refute_includes ObjectSpace.dump(o1), '"embedded":true'
+    o1.remove_instance_variable(:@foo)
+    assert_includes ObjectSpace.dump(o1), '"embedded":true'
+
+    o2.instance_variable_set(:@a, 0)
+    o2.instance_variable_set(:@b, 1)
+    o2.instance_variable_set(:@c, 2)
+    assert_includes ObjectSpace.dump(o2), '"embedded":true'
+
+    assert_equal(0, o1.a)
+    assert_equal(1, o1.b)
+    assert_equal(2, o1.c)
+    assert_equal(0, o2.a)
+    assert_equal(1, o2.b)
+    assert_equal(2, o2.c)
+  end
+
   def test_convert_string
     o = Object.new
     def o.to_s; 1; end