2009-02-25  Geoffrey Garen  <ggaren@apple.com>

        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  <ggaren@apple.com>

        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):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@41232 268f45cc-cd09-0410-ab3c-d52691b4dbfc