Changeset 41232 in webkit for trunk/JavaScriptCore/runtime/StructureChain.h

Timestamp:

Feb 25, 2009, 3:44:07 PM (16 years ago)

Author:

[email protected]

Message:

JavaScriptCore:

2009-02-25 Geoffrey Garen <​[email protected]>

Reviewed by Maciej Stachowiak.

Fixed <rdar://problem/6611174> REGRESSION (r36701): Unable to select
messages on hotmail (24052)

The bug was that for-in enumeration used a cached prototype chain without
validating that it was up-to-date.

This led me to refactor prototype chain caching so it was easier to work
with and harder to get wrong.

After a bit of inlining, this patch is performance-neutral on SunSpider
and the v8 benchmarks.

• interpreter/Interpreter.cpp: (JSC::Interpreter::tryCachePutByID): (JSC::Interpreter::tryCacheGetByID):
• jit/JITStubs.cpp: (JSC::JITStubs::tryCachePutByID): (JSC::JITStubs::tryCacheGetByID): (JSC::JITStubs::cti_op_get_by_id_proto_list): Use the new refactored goodness. See lines beginning with "-" and smile.

• runtime/JSGlobalObject.h: (JSC::Structure::prototypeForLookup): A shout out to const.

• runtime/JSPropertyNameIterator.h: (JSC::JSPropertyNameIterator::next): We can use a pointer comparison to see if our cached structure chain is equal to the object's structure chain, since in the case of a cache hit, we share references to the same structure chain.

• runtime/Operations.h: (JSC::countPrototypeChainEntriesAndCheckForProxies): Use the new refactored goodness.

• runtime/PropertyNameArray.h: (JSC::PropertyNameArray::PropertyNameArray): (JSC::PropertyNameArray::setShouldCache): (JSC::PropertyNameArray::shouldCache): Renamed "cacheable" to "shouldCache" to communicate that the client is specifying a recommendation, not a capability.

• runtime/Structure.cpp: (JSC::Structure::Structure): No need to initialize a RefPtr. (JSC::Structure::getEnumerablePropertyNames): Moved some code into helper functions.

(JSC::Structure::prototypeChain): New centralized accessor for a prototype
chain. Revalidates on every access, since the objects in the prototype
chain may have mutated.

(JSC::Structure::isValid): Helper function for revalidating a cached
prototype chain.

(JSC::Structure::getEnumerableNamesFromPropertyTable):
(JSC::Structure::getEnumerableNamesFromClassInfoTable): Factored out of
getEnumerablePropertyNames.

• runtime/Structure.h:

• runtime/StructureChain.cpp: (JSC::StructureChain::StructureChain):
• runtime/StructureChain.h: (JSC::StructureChain::create): No need for structureChainsAreEqual, since we use pointer equality now. Refactored StructureChain to make a little more sense and eliminate special cases for null prototypes.

LayoutTests:

2009-02-24 Geoffrey Garen <​[email protected]>

Reviewed by Maciej Stachowiak.

Added a test for <rdar://problem/6611174> REGRESSION (r36701): Unable to
select messages on hotmail (24052)

• fast/js/for-in-cached-expected.txt: Added.
• fast/js/for-in-cached.html: Added.
• fast/js/resources/for-in-cached.js: Added. (forIn):

File:

• trunk/JavaScriptCore/runtime/StructureChain.h (modified) (1 diff)

trunk/JavaScriptCore/runtime/StructureChain.h

@@ -38 +38 @@
     class StructureChain : public RefCounted<StructureChain> {
     public:
-        static PassRefPtr<StructureChain> create(Structure* structure) { return adoptRef(new StructureChain(structure)); }
-
+        static PassRefPtr<StructureChain> create(Structure* head) { return adoptRef(new StructureChain(head)); }
         RefPtr<Structure>* head() { return m_vector.get(); }
 
     private:
-        StructureChain(Structure* structure);
+        StructureChain(Structure* head);
 
         OwnArrayPtr<RefPtr<Structure> > m_vector;
     };
 
-    bool structureChainsAreEqual(StructureChain*, StructureChain*);
-
 } // namespace JSC