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    fourthTier: DFG should support switch_string · 5c826c0d
    oliver@apple.com authored
    https://bugs.webkit.org/show_bug.cgi?id=117967
    
    Source/JavaScriptCore:
    
    Reviewed by Sam Weinig.
    
    Add a reusable binary switch creator.
    
    Implement switch on string using three modes:
    
    - Binary switch on StringImpl* in the case of identifiers.
    
    - Trie of binary switches on characters in the case of a not-too-big
      switch over not-too-big 8-bit strings.
    
    - Hash lookup if all else fails.
    
    Anywhere from a 2x to 3x speed-up on microbenchmarks that stress
    string switches. 25-35% speed-up on HashMap tests. 4% speed-up on
    pdfjs.
    
    * JavaScriptCore.xcodeproj/project.pbxproj:
    * bytecode/JumpTable.h:
    (StringJumpTable):
    (JSC::StringJumpTable::clear):
    * dfg/DFGBackwardsPropagationPhase.cpp:
    (JSC::DFG::BackwardsPropagationPhase::propagate):
    * dfg/DFGBinarySwitch.cpp: Added.
    (DFG):
    (JSC::DFG::BinarySwitch::BinarySwitch):
    (JSC::DFG::BinarySwitch::advance):
    (JSC::DFG::BinarySwitch::build):
    * dfg/DFGBinarySwitch.h: Added.
    (DFG):
    (BinarySwitch):
    (JSC::DFG::BinarySwitch::caseIndex):
    (JSC::DFG::BinarySwitch::caseValue):
    (JSC::DFG::BinarySwitch::fallThrough):
    (JSC::DFG::BinarySwitch::Case::Case):
    (Case):
    (JSC::DFG::BinarySwitch::Case::operator<):
    (JSC::DFG::BinarySwitch::BranchCode::BranchCode):
    (BranchCode):
    * dfg/DFGByteCodeParser.cpp:
    (JSC::DFG::ByteCodeParser::parseBlock):
    * dfg/DFGCapabilities.cpp:
    (JSC::DFG::capabilityLevel):
    * dfg/DFGFixupPhase.cpp:
    (JSC::DFG::FixupPhase::fixupNode):
    * dfg/DFGJITCompiler.cpp:
    (JSC::DFG::JITCompiler::link):
    * dfg/DFGLazyJSValue.cpp:
    (JSC::DFG::LazyJSValue::getValue):
    (JSC::DFG::equalToStringImpl):
    (DFG):
    (JSC::DFG::LazyJSValue::strictEqual):
    (JSC::DFG::LazyJSValue::dump):
    * dfg/DFGLazyJSValue.h:
    (JSC::DFG::LazyJSValue::knownStringImpl):
    (LazyJSValue):
    (JSC::DFG::LazyJSValue::stringImpl):
    (JSC::DFG::LazyJSValue::switchLookupValue):
    * dfg/DFGNode.cpp:
    (WTF::printInternal):
    * dfg/DFGNode.h:
    * dfg/DFGOperations.cpp:
    * dfg/DFGOperations.h:
    * dfg/DFGSpeculativeJIT.cpp:
    (JSC::DFG::SpeculativeJIT::emitSwitchChar):
    (JSC::DFG::SpeculativeJIT::StringSwitchCase::operator<):
    (DFG):
    (JSC::DFG::SpeculativeJIT::emitBinarySwitchStringRecurse):
    (JSC::DFG::SpeculativeJIT::emitSwitchStringOnString):
    (JSC::DFG::SpeculativeJIT::emitSwitchString):
    (JSC::DFG::SpeculativeJIT::emitSwitch):
    (JSC::DFG::SpeculativeJIT::addBranch):
    * dfg/DFGSpeculativeJIT.h:
    (JSC::DFG::SpeculativeJIT::callOperation):
    (JSC::DFG::SpeculativeJIT::branch8):
    (SpeculativeJIT):
    (JSC::DFG::SpeculativeJIT::StringSwitchCase::StringSwitchCase):
    (StringSwitchCase):
    * ftl/FTLLowerDFGToLLVM.cpp:
    (JSC::FTL::LowerDFGToLLVM::compileSwitch):
    * runtime/Options.h:
    (JSC):
    
    Source/WTF:
    
    Reviewed by Sam Weinig.
    
    Make it possible to compare a RefPtr<StringImpl> and a StringImpl* without
    having to ref the StringImpl.
    
    * wtf/text/StringHash.h:
    (WTF::StringHash::equal):
    
    LayoutTests:
    
    Reviewed by Sam Weinig.
    
    * fast/js/regress/script-tests/switch-string-basic-big-var.js: Added.
    (foo):
    (make):
    * fast/js/regress/script-tests/switch-string-basic-big.js: Added.
    (foo):
    (make):
    * fast/js/regress/script-tests/switch-string-basic-var.js: Added.
    (foo):
    (make):
    * fast/js/regress/script-tests/switch-string-basic.js: Added.
    (foo):
    * fast/js/regress/script-tests/switch-string-big-length-tower-var.js: Added.
    (foo):
    * fast/js/regress/script-tests/switch-string-length-tower-var.js: Added.
    (foo):
    * fast/js/regress/script-tests/switch-string-length-tower.js: Added.
    (foo):
    * fast/js/regress/script-tests/switch-string-short.js: Added.
    (foo):
    * fast/js/regress/switch-string-basic-big-expected.txt: Added.
    * fast/js/regress/switch-string-basic-big-var-expected.txt: Added.
    * fast/js/regress/switch-string-basic-big-var.html: Added.
    * fast/js/regress/switch-string-basic-big.html: Added.
    * fast/js/regress/switch-string-basic-expected.txt: Added.
    * fast/js/regress/switch-string-basic-var-expected.txt: Added.
    * fast/js/regress/switch-string-basic-var.html: Added.
    * fast/js/regress/switch-string-basic.html: Added.
    * fast/js/regress/switch-string-big-length-tower-var-expected.txt: Added.
    * fast/js/regress/switch-string-big-length-tower-var.html: Added.
    * fast/js/regress/switch-string-length-tower-expected.txt: Added.
    * fast/js/regress/switch-string-length-tower-var-expected.txt: Added.
    * fast/js/regress/switch-string-length-tower-var.html: Added.
    * fast/js/regress/switch-string-length-tower.html: Added.
    * fast/js/regress/switch-string-short-expected.txt: Added.
    * fast/js/regress/switch-string-short.html: Added.
    
    Conflicts:
    	Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj
    
    git-svn-id: http://svn.webkit.org/repository/webkit/trunk@153248 268f45cc-cd09-0410-ab3c-d52691b4dbfc
    5c826c0d