Simplify known class check for singletons

Singleton classes should only ever be attached to one object. This means
that checking for the object should be the same as checking for the
class. This should be slightly faster by avoiding one memory acccess as
well as allowing us to skip checking if the receiver is a heap object.

This will be most common for calling class methods.

1 files changed, 31 insertions, 0 deletions

diff --git a/bootstraptest/test_yjit.rb b/bootstraptest/test_yjit.rb
index 129903bf9c..e15728fd98 100644
--- a/bootstraptest/test_yjit.rb
+++ b/bootstraptest/test_yjit.rb
@@ -1153,3 +1153,34 @@ assert_equal '7', %q{
   foo(5,2)
   foo(5,2)
 }
+
+# Call to object with singleton
+assert_equal '123', %q{
+  obj = Object.new
+  def obj.foo
+    123
+  end
+
+  def foo(obj)
+    obj.foo()
+  end
+
+  foo(obj)
+  foo(obj)
+}
+
+# Call to singleton class
+assert_equal '123', %q{
+  class Foo
+    def self.foo
+      123
+    end
+  end
+
+  def foo(obj)
+    obj.foo()
+  end
+
+  foo(Foo)
+  foo(Foo)
+}