Changeset 89219 in webkit for trunk/Source/JavaScriptCore/runtime/JSGlobalObjectFunctions.cpp

Timestamp:

Jun 19, 2011, 12:47:45 PM (14 years ago)

Author:

[email protected]

Message:

2011-06-17 Oliver Hunt <​[email protected]>

Reviewed by Gavin Barraclough.

JSONP is unnecessarily slow
​https://bugs.webkit.org/show_bug.cgi?id=62920

JSONP has unfortunately become a fairly common idiom online, yet
it triggers very poor performance in JSC as we end up doing codegen
for a large number of property accesses that will

• only be run once, so the vast amount of logic we dump to handle caching of accesses is unnecessary.
• We are doing codegen that is directly proportional to just creating the object in the first place.

This patch extends the use of the literal parser to JSONP-like structures
in global code, handling a number of different forms I have seen online.
In an extreme case this improves performance of JSONP by more than 2x
due to removal of code generation and execution time, and a few optimisations
that I made to the parser itself.

• API/JSValueRef.cpp: (JSValueMakeFromJSONString):
• interpreter/Interpreter.cpp: (JSC::Interpreter::callEval): (JSC::Interpreter::execute):
• parser/Lexer.cpp: (JSC::Lexer::isKeyword):
• parser/Lexer.h:
• runtime/JSGlobalObjectFunctions.cpp: (JSC::globalFuncEval):
• runtime/JSONObject.cpp: (JSC::JSONProtoFuncParse):
• runtime/LiteralParser.cpp: (JSC::LiteralParser::tryJSONPParse): (JSC::LiteralParser::makeIdentifier): (JSC::LiteralParser::Lexer::lex): (JSC::LiteralParser::Lexer::next): (JSC::isSafeStringCharacter): (JSC::LiteralParser::Lexer::lexString): (JSC::LiteralParser::Lexer::lexNumber): (JSC::LiteralParser::parse):
• runtime/LiteralParser.h: (JSC::LiteralParser::LiteralParser): (JSC::LiteralParser::tryLiteralParse): (JSC::LiteralParser::Lexer::Lexer):

File:

• trunk/Source/JavaScriptCore/runtime/JSGlobalObjectFunctions.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/runtime/JSGlobalObjectFunctions.cpp

@@ -446 +446 @@
     UString s = x.toString(exec);
 
-    LiteralParser preparser(exec, s, LiteralParser::NonStrictJSON);
+    LiteralParser preparser(exec, s.characters(), s.length(), LiteralParser::NonStrictJSON);
     if (JSValue parsedObject = preparser.tryLiteralParse())
         return JSValue::encode(parsedObject);