Changeset 266117 in webkit for trunk/Source/JavaScriptCore/parser/SyntaxChecker.h

Timestamp:

Aug 25, 2020, 8:58:40 AM (5 years ago)

Author:

Alexey Shvayka

Message:

Invalid early error for object literal method named "proto"
​https://bugs.webkit.org/show_bug.cgi?id=215760

Reviewed by Ross Kirsling.

JSTests:

• test262/expectations.yaml: Mark 2 test cases as passing.

Source/JavaScriptCore:

According to Annex B [1], { __proto__: null, __proto__() {} } is a valid object literal as the second
__proto__ wasn't obtained from PropertyDefinition : PropertyName : AssignmentExpression production.
Currently, JSC throws an early SyntaxError, unlike V8 and SpiderMonkey.

Since a method needs super binding, the most straightforward fix would be adding SuperBinding field
to SyntaxChecker::Property and exposing it via an accessor. However, given that Property is a very
common structure, this approach would noticeably increase memory pressure during parsing.

Instead, this patch reworks SyntaxChecker::Property to accept isUnderscoreProtoSetter parameter,
removing optional name field, its accessor, and shouldCheckPropertyForUnderscoreProtoDuplicate(),
which reduces sizeof(SyntaxChecker::Property) by a factor of 8: from 16 to 2 bytes.
Also, this change avoids two extra makeNumericIdentifier() calls, speeding up numeric keys parsing.

This approach is feasible because "proto" is the only identifier-based early error for object
literals [2], with no such errors being added in upcoming stage 2-4 proposals.

Additionally, this patch removes strict / complete bool parameter from {parse,create}Property()
signatures as a) it was always true, b) is now unused, and c) strict mode can be checked via scope.

[1]: ​https://tc39.es/ecma262/#sec-__proto__-property-names-in-object-initializers
[2]: ​https://tc39.es/ecma262/#sec-object-initializer-static-semantics-early-errors

• parser/ASTBuilder.h:

(JSC::ASTBuilder::createGetterOrSetterProperty):
(JSC::ASTBuilder::createProperty):
(JSC::ASTBuilder::isUnderscoreProtoSetter const):
(JSC::ASTBuilder::getName const): Deleted.

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

(JSC::Parser<LexerType>::parseClass):
(JSC::Parser<LexerType>::parseProperty):
(JSC::Parser<LexerType>::parseGetterSetter):
(JSC::Parser<LexerType>::parseObjectLiteral):
(JSC::Parser<LexerType>::shouldCheckPropertyForUnderscoreProtoDuplicate): Deleted.

• parser/Parser.h:
• parser/SyntaxChecker.h:

(JSC::SyntaxChecker::SyntaxChecker):
(JSC::SyntaxChecker::Property::Property):
(JSC::SyntaxChecker::Property::operator!):
(JSC::SyntaxChecker::createProperty):
(JSC::SyntaxChecker::createGetterOrSetterProperty):
(JSC::SyntaxChecker::operatorStackPop):

File:

• trunk/Source/JavaScriptCore/parser/SyntaxChecker.h (modified) (6 diffs)

trunk/Source/JavaScriptCore/parser/SyntaxChecker.h

@@ -65 +65 @@
     };
     
-    SyntaxChecker(VM& , void*)
+    SyntaxChecker(VM& vm, void*)
+        : m_vm(vm)
     {
     }
@@ -100 +101 @@
     struct Property {
         ALWAYS_INLINE Property(void* = nullptr)
-            : type((PropertyNode::Type)0)
-        {
-        }
-        ALWAYS_INLINE Property(const Identifier* ident, PropertyNode::Type ty)
-            : name(ident)
-            , type(ty)
-        {
-        }
-        ALWAYS_INLINE Property(PropertyNode::Type ty)
-            : name(nullptr)
-            , type(ty)
+        {
+        }
+        ALWAYS_INLINE Property(PropertyNode::Type type)
+            : type(type)
+        {
+        }
+        ALWAYS_INLINE Property(PropertyNode::Type type, bool isUnderscoreProtoSetter)
+            : type(type)
+            , isUnderscoreProtoSetter(isUnderscoreProtoSetter)
         {
         }
         ALWAYS_INLINE bool operator!() { return !type; }
-        const Identifier* name;
-        PropertyNode::Type type;
+        PropertyNode::Type type { static_cast<PropertyNode::Type>(0) };
+        bool isUnderscoreProtoSetter { false };
     };
     typedef int PropertyList;
@@ -216 +215 @@
     int createArgumentsList(const JSTokenLocation&, int) { return ArgumentsListResult; }
     int createArgumentsList(const JSTokenLocation&, int, int) { return ArgumentsListResult; }
-    Property createProperty(const Identifier* name, int, PropertyNode::Type type, PropertyNode::PutType, bool complete, SuperBinding, InferName, ClassElementTag)
-    {
-        if (!complete)
-            return Property(type);
-        ASSERT(name);
-        return Property(name, type);
-    }
-    Property createProperty(int, PropertyNode::Type type, PropertyNode::PutType, bool, SuperBinding, ClassElementTag)
-    {
-        return Property(type);
-    }
-    Property createProperty(VM& vm, ParserArena& parserArena, double name, int, PropertyNode::Type type, PropertyNode::PutType, bool complete, SuperBinding, ClassElementTag)
-    {
-        if (!complete)
-            return Property(type);
-        return Property(&parserArena.identifierArena().makeNumericIdentifier(vm, name), type);
-    }
-    Property createProperty(int, int, PropertyNode::Type type, PropertyNode::PutType, bool, SuperBinding, ClassElementTag)
-    {
-        return Property(type);
-    }
-    Property createProperty(const Identifier*, int, int, PropertyNode::Type type, PropertyNode::PutType, bool, SuperBinding, ClassElementTag)
+    Property createProperty(const Identifier* name, int, PropertyNode::Type type, PropertyNode::PutType, SuperBinding superBinding, InferName, ClassElementTag)
+    {
+        return Property(type, PropertyNode::isUnderscoreProtoSetter(m_vm, name, type, superBinding == SuperBinding::Needed));
+    }
+    Property createProperty(int, PropertyNode::Type type, PropertyNode::PutType, SuperBinding, ClassElementTag)
+    {
+        return Property(type);
+    }
+    Property createProperty(VM&, ParserArena&, double, int, PropertyNode::Type type, PropertyNode::PutType, SuperBinding, ClassElementTag)
+    {
+        return Property(type);
+    }
+    Property createProperty(int, int, PropertyNode::Type type, PropertyNode::PutType, SuperBinding, ClassElementTag)
+    {
+        return Property(type);
+    }
+    Property createProperty(const Identifier*, int, int, PropertyNode::Type type, PropertyNode::PutType, SuperBinding, ClassElementTag)
     {
         return Property(type);
@@ -292 +286 @@
 
     int appendConstDecl(const JSTokenLocation&, int, const Identifier*, int) { return StatementResult; }
-    Property createGetterOrSetterProperty(const JSTokenLocation&, PropertyNode::Type type, bool strict, const Identifier* name, const ParserFunctionInfo<SyntaxChecker>&, ClassElementTag)
-    {
-        ASSERT(name);
-        if (!strict)
-            return Property(type);
-        return Property(name, type);
-    }
-    Property createGetterOrSetterProperty(const JSTokenLocation&, PropertyNode::Type type, bool, int, const ParserFunctionInfo<SyntaxChecker>&, ClassElementTag)
-    {
-        return Property(type);
-    }
-    Property createGetterOrSetterProperty(VM& vm, ParserArena& parserArena, const JSTokenLocation&, PropertyNode::Type type, bool strict, double name, const ParserFunctionInfo<SyntaxChecker>&, ClassElementTag)
-    {
-        if (!strict)
-            return Property(type);
-        return Property(&parserArena.identifierArena().makeNumericIdentifier(vm, name), type);
+    Property createGetterOrSetterProperty(const JSTokenLocation&, PropertyNode::Type type, const Identifier*, const ParserFunctionInfo<SyntaxChecker>&, ClassElementTag)
+    {
+        return Property(type);
+    }
+    Property createGetterOrSetterProperty(const JSTokenLocation&, PropertyNode::Type type, int, const ParserFunctionInfo<SyntaxChecker>&, ClassElementTag)
+    {
+        return Property(type);
+    }
+    Property createGetterOrSetterProperty(VM&, ParserArena&, const JSTokenLocation&, PropertyNode::Type type, double, const ParserFunctionInfo<SyntaxChecker>&, ClassElementTag)
+    {
+        return Property(type);
     }
 
@@ -340 +329 @@
     void assignmentStackAppend(int& assignmentStackDepth, int, int, int, int, Operator) { assignmentStackDepth = 1; }
     int createAssignment(const JSTokenLocation&, int& assignmentStackDepth, int, int, int, int) { assignmentStackDepth = 0; return AssignmentExpr; }
-    const Identifier* getName(const Property& property) const { return property.name; }
     PropertyNode::Type getType(const Property& property) const { return property.type; }
+    bool isUnderscoreProtoSetter(const Property& property) const { return property.isUnderscoreProtoSetter; }
     bool isResolve(ExpressionType expr) const { return expr == ResolveExpr || expr == ResolveEvalExpr; }
     ExpressionType createDestructuringAssignment(const JSTokenLocation&, int, ExpressionType)
@@ -448 +437 @@
 
 private:
+    VM& m_vm;
     int m_topBinaryExpr;
     int m_topUnaryToken;