Changeset 275439 in webkit for trunk/Source/JavaScriptCore/parser/ASTBuilder.h

Timestamp:

Apr 2, 2021, 2:20:45 PM (4 years ago)

Author:

Alexey Shvayka

Message:

Reduce bytecode instruction count emitted for class extends
​https://bugs.webkit.org/show_bug.cgi?id=223884

Reviewed by Yusuke Suzuki.

JSTests:

• ChakraCore/test/Error/validate_line_column.baseline-jsc:

Source/JavaScriptCore:

This patch adds a variant of globalFuncSetPrototypeDirect() that throws on
invalid Prototype values (instead of ignoring them) and utilizes it in
ClassExprNode::emitBytecode(), removing equivalent checks.

Throwing for invalid superclass.prototype value after setting the Prototype
of constructor is unobservable because it's a newly created extensible object
and superclass is a proven object.

The fact that Prototype set can throw only in case of superclass.prototype
allows keeping descriptive error message via custom appender. To find "extends"
in a source code, ClassExprNode is made an instance of ThrowableExpressionData.

This change reduces the number of emitted bytecodes by 4, and fixes IsConstructor's
error [1] to point to correct source code location.

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

• builtins/BuiltinNames.h:
• bytecode/LinkTimeConstant.h:
• bytecompiler/BytecodeGenerator.cpp:

(JSC::BytecodeGenerator::emitDirectSetPrototypeOf):

• bytecompiler/BytecodeGenerator.h:
• bytecompiler/NodesCodegen.cpp:

(JSC::PropertyListNode::emitPutConstantProperty):
(JSC::ClassExprNode::emitBytecode):

• parser/ASTBuilder.h:

(JSC::ASTBuilder::createClassExpr):

• parser/Nodes.h:
• parser/Parser.cpp:

(JSC::Parser<LexerType>::parseClass):

• parser/SyntaxChecker.h:

(JSC::SyntaxChecker::createClassExpr):

• runtime/ExceptionHelpers.cpp:

(JSC::invalidPrototypeSourceAppender):
(JSC::createInvalidPrototypeError):

• runtime/ExceptionHelpers.h:
• runtime/JSGlobalObject.cpp:

(JSC::JSGlobalObject::init):

• runtime/JSGlobalObjectFunctions.cpp:

(JSC::JSC_DEFINE_HOST_FUNCTION):

• runtime/JSGlobalObjectFunctions.h:

File:

• trunk/Source/JavaScriptCore/parser/ASTBuilder.h (modified) (1 diff)

trunk/Source/JavaScriptCore/parser/ASTBuilder.h

@@ -413 +413 @@
 
     ClassExprNode* createClassExpr(const JSTokenLocation& location, const ParserClassInfo<ASTBuilder>& classInfo, VariableEnvironment& classEnvironment, ExpressionNode* constructor,
-        ExpressionNode* parentClass, PropertyListNode* classElements)
+        ExpressionNode* parentClass, PropertyListNode* classElements, const JSTextPosition& start, const JSTextPosition& divot, const JSTextPosition& end)
     {
         SourceCode source = m_sourceCode->subExpression(classInfo.startOffset, classInfo.endOffset, classInfo.startLine, classInfo.startColumn);
-        return new (m_parserArena) ClassExprNode(location, *classInfo.className, source, classEnvironment, constructor, parentClass, classElements);
+        ClassExprNode* node = new (m_parserArena) ClassExprNode(location, *classInfo.className, source, classEnvironment, constructor, parentClass, classElements);
+        setExceptionLocation(node, start, divot, end);
+        return node;
     }