Changeset 264748 in webkit for trunk/Source/JavaScriptCore/bytecompiler

Timestamp:

Jul 23, 2020, 12:28:49 AM (5 years ago)

Author:

Alexey Shvayka

Message:

Remove emitIsUndefined() from ClassExprNode::emitBytecode()
​https://bugs.webkit.org/show_bug.cgi?id=214645

Reviewed by Darin Adler.

This change removes superclass === undefined check because it's missing from
the spec [1] and isn't a common case. No behavior change: values except null are
passed to OpIsConstructor, resulting in the same error being thrown for undefined.

Test: LayoutTests/js/class-syntax-extends.html

[1]: ​https://tc39.es/ecma262/#sec-runtime-semantics-classdefinitionevaluation (step 5.e)

• bytecompiler/NodesCodegen.cpp:

(JSC::ClassExprNode::emitBytecode):

File:

• trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp

@@ -4893 +4893 @@
         RefPtr<RegisterID> tempRegister = generator.newTemporary();
 
-        Ref<Label> superclassIsUndefinedLabel = generator.newLabel();
-        generator.emitJumpIfTrue(generator.emitIsUndefined(tempRegister.get(), superclass.get()), superclassIsUndefinedLabel.get());
-
         Ref<Label> superclassIsNullLabel = generator.newLabel();
         generator.emitJumpIfTrue(generator.emitIsNull(tempRegister.get(), superclass.get()), superclassIsNullLabel.get());
@@ -4901 +4898 @@
         Ref<Label> superclassIsConstructorLabel = generator.newLabel();
         generator.emitJumpIfTrue(generator.emitIsConstructor(tempRegister.get(), superclass.get()), superclassIsConstructorLabel.get());
-        generator.emitLabel(superclassIsUndefinedLabel.get());
         generator.emitThrowTypeError("The superclass is not a constructor."_s);
         generator.emitLabel(superclassIsConstructorLabel.get());