Changeset 262165 in webkit for trunk/Source/JavaScriptCore/bytecompiler

Timestamp:

May 26, 2020, 3:16:10 PM (5 years ago)

Author:

Alexey Shvayka

Message:

IteratorClose should suppress GetMethod errors
​https://bugs.webkit.org/show_bug.cgi?id=212378

Reviewed by Keith Miller.

JSTests:

• stress/custom-iterators.js:
• stress/iterator-return-abrupt-lookup-builtins.js: Added.
• test262/expectations.yaml: Mark 4 test cases as passing.

Source/JavaScriptCore:

This patch implements recent spec change [1] that prevents "return" method lookup error
from overriding outer exception, aligning JSC with V8 and SpiderMonkey.

It is accomplished by moving pushTry() before emitGetById() in BytecodeGenerator.cpp
(covered by test262 suite) and removal of RETURN_IF_EXCEPTION in IteratorOperations.cpp
(added a stress test).

Before this patch, JSC partly implemented the spec change [1] by suppressing TypeError
if "return" method of iterator was not callable.

BytecodeGenerator::emitDelegateYield() is intentionally left unchanged.
Also, this patch utilizes emitIteratorGenericClose() to avoid code duplication.
for/of microbenchmarks are neutral.

[1]: ​https://github.com/tc39/ecma262/pull/1408

• bytecompiler/BytecodeGenerator.cpp:

(JSC::BytecodeGenerator::emitGenericEnumeration):
(JSC::BytecodeGenerator::emitEnumeration):

• runtime/IteratorOperations.cpp:

(JSC::iteratorClose):

File:

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

trunk/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

@@ -4083 +4083 @@
             restoreScopeRegister();
 
-            Ref<Label> finallyDone = newLabel();
-
-            RefPtr<RegisterID> returnMethod = emitGetById(newTemporary(), iterator.get(), propertyNames().returnKeyword);
-            emitJumpIfTrue(emitIsUndefined(newTemporary(), returnMethod.get()), finallyDone.get());
-
             Ref<Label> returnCallTryStart = newLabel();
             emitLabel(returnCallTryStart.get());
             TryData* returnCallTryData = pushTry(returnCallTryStart.get(), catchLabel.get(), HandlerType::SynthesizedCatch);
 
-            CallArguments returnArguments(*this, nullptr);
-            move(returnArguments.thisRegister(), iterator.get());
-            emitCall(value.get(), returnMethod.get(), NoExpectedFunction, returnArguments, node->divot(), node->divotStart(), node->divotEnd(), DebuggableCall::No);
-
-            if (isForAwait)
-                emitAwait(value.get());
-
-            emitJumpIfTrue(emitIsObject(newTemporary(), value.get()), finallyDone.get());
-            emitThrowTypeError("Iterator result interface is not an object."_s);
-
-            emitLabel(finallyDone.get());
+            emitIteratorGenericClose(iterator.get(), node, shouldEmitAwait);
+            Ref<Label> finallyDone = newEmittedLabel();
             emitFinallyCompletion(finallyContext, endCatchLabel.get());
 
@@ -4239 +4225 @@
             restoreScopeRegister();
 
-            Ref<Label> finallyDone = newLabel();
-
-            RefPtr<RegisterID> returnMethod = emitGetById(newTemporary(), iterator.get(), propertyNames().returnKeyword);
-            emitJumpIfTrue(emitIsUndefined(newTemporary(), returnMethod.get()), finallyDone.get());
-
             Ref<Label> returnCallTryStart = newLabel();
             emitLabel(returnCallTryStart.get());
             TryData* returnCallTryData = pushTry(returnCallTryStart.get(), catchLabel.get(), HandlerType::SynthesizedCatch);
 
-            CallArguments returnArguments(*this, nullptr);
-            move(returnArguments.thisRegister(), iterator.get());
-            emitCall(value.get(), returnMethod.get(), NoExpectedFunction, returnArguments, node->divot(), node->divotStart(), node->divotEnd(), DebuggableCall::No);
-
-            emitJumpIfTrue(emitIsObject(newTemporary(), value.get()), finallyDone.get());
-            emitThrowTypeError("Iterator result interface is not an object."_s);
-
-            emitLabel(finallyDone.get());
+            emitIteratorGenericClose(iterator.get(), node, EmitAwait::No);
+            Ref<Label> finallyDone = newEmittedLabel();
             emitFinallyCompletion(finallyContext, endCatchLabel.get());