Changeset 41232 in webkit for trunk/JavaScriptCore/runtime/Structure.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/Structure.h (modified) (4 diffs)

trunk/JavaScriptCore/runtime/Structure.h

@@ -88 +88 @@
 
         JSValuePtr storedPrototype() const { return m_prototype; }
-        JSValuePtr prototypeForLookup(ExecState*); 
+        JSValuePtr prototypeForLookup(ExecState*) const;
+        StructureChain* prototypeChain(ExecState*) const;
 
         Structure* previousID() const { return m_previous.get(); }
-
-        StructureChain* createCachedPrototypeChain();
-        void setCachedPrototypeChain(PassRefPtr<StructureChain> cachedPrototypeChain) { m_cachedPrototypeChain = cachedPrototypeChain; }
-        StructureChain* cachedPrototypeChain() const { return m_cachedPrototypeChain.get(); }
 
         void growPropertyStorageCapacity();
@@ -114 +111 @@
         size_t put(const Identifier& propertyName, unsigned attributes);
         size_t remove(const Identifier& propertyName);
-        void getEnumerablePropertyNamesInternal(PropertyNameArray&);
+        void getEnumerableNamesFromPropertyTable(PropertyNameArray&);
+        void getEnumerableNamesFromClassInfoTable(ExecState*, const ClassInfo*, PropertyNameArray&);
 
         void expandPropertyMapHashTable();
@@ -145 +143 @@
             return m_offset == noOffset ? 0 : m_offset + 1;
         }
+        
+        bool isValid(ExecState*, StructureChain* cachedPrototypeChain) const;
 
         static const unsigned emptyEntryIndex = 0;
@@ -155 +155 @@
 
         JSValuePtr m_prototype;
-        RefPtr<StructureChain> m_cachedPrototypeChain;
+        mutable RefPtr<StructureChain> m_cachedPrototypeChain;
 
         RefPtr<Structure> m_previous;