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fpizlo@apple.com authored
https://bugs.webkit.org/show_bug.cgi?id=120781 Reviewed by Mark Hahnenberg. Roll this back in with a build fix. - Use some method table hacks to detect if the CheckStructure optimization is valid for to_this. - Introduce a FinalObjectUse and use it for ToThis->Identity conversion. This looks like it might be perf-neutral on the major benchmarks, but it introduces some horrible performance cliffs. For example if you add methods to the Array prototype, you'll get horrible performance cliffs. As in virtual calls to C++ every time you call a JS function even if it's inlined. LongSpider/3d-cube appears to hit this. * dfg/DFGAbstractInterpreterInlines.h: (JSC::DFG::::executeEffects): * dfg/DFGByteCodeParser.cpp: (JSC::DFG::ByteCodeParser::parseBlock): * dfg/DFGFixupPhase.cpp: (JSC::DFG::FixupPhase::fixupNode): * dfg/DFGRepatch.cpp: (JSC::DFG::emitPutTransitionStub): * dfg/DFGSafeToExecute.h: (JSC::DFG::SafeToExecuteEdge::operator()): * dfg/DFGSpeculativeJIT.cpp: (JSC::DFG::SpeculativeJIT::speculateFinalObject): (JSC::DFG::SpeculativeJIT::speculate): * dfg/DFGSpeculativeJIT.h: * dfg/DFGSpeculativeJIT32_64.cpp: (JSC::DFG::SpeculativeJIT::compile): * dfg/DFGSpeculativeJIT64.cpp: (JSC::DFG::SpeculativeJIT::compile): * dfg/DFGUseKind.cpp: (WTF::printInternal): * dfg/DFGUseKind.h: (JSC::DFG::typeFilterFor): (JSC::DFG::isCell): git-svn-id: http://svn.webkit.org/repository/webkit/trunk@155201 268f45cc-cd09-0410-ab3c-d52691b4dbfc
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