Limit maximum number of IVs on a shape on T_OBJECTS

Create SHAPE_MAX_NUM_IVS (currently 50) and limit all shapes of
T_OBJECTS to that number of IVs. When a shape with a T_OBJECT has more than 50 IVs, fall back to the
obj_too_complex shape which uses hash lookup for ivs.

Note that a previous version of this commit
78fcc9847a9db6d42c8c263154ec05903a370b6b was reverted in
88f2b94065be3fcd6769a3f132cfee8ecfb663b8 because it did not account for
non-T_OBJECTS

1 files changed, 20 insertions, 0 deletions

diff --git a/test/ruby/test_shapes.rb b/test/ruby/test_shapes.rb
index b2cd79ab12..85adcd4a80 100644
--- a/test/ruby/test_shapes.rb
+++ b/test/ruby/test_shapes.rb
@@ -88,6 +88,26 @@ class TestShapes < Test::Unit::TestCase
     assert_predicate RubyVM::Shape.of(tc), :too_complex?
   end
 
+  def test_too_many_ivs_on_obj
+    obj = Object.new
+
+    (RubyVM::Shape::SHAPE_MAX_NUM_IVS + 1).times do
+      obj.instance_variable_set(:"@a#{_1}", 1)
+    end
+
+    assert_predicate RubyVM::Shape.of(obj), :too_complex?
+  end
+
+  def test_too_many_ivs_on_class
+    obj = Class.new
+
+    (RubyVM::Shape::SHAPE_MAX_NUM_IVS + 1).times do
+      obj.instance_variable_set(:"@a#{_1}", 1)
+    end
+
+    assert_false RubyVM::Shape.of(obj).too_complex?
+  end
+
   def test_too_complex_ractor
     assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
     begin;