CodeBlock.h   [plain text]

/*
 * Copyright (C) 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
 * Copyright (C) 2008 Cameron Zwarich <cwzwarich@uwaterloo.ca>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef CodeBlock_h
#define CodeBlock_h

#include "ArrayProfile.h"
#include "ByValInfo.h"
#include "BytecodeConventions.h"
#include "CallLinkInfo.h"
#include "CallReturnOffsetToBytecodeOffset.h"
#include "CodeBlockHash.h"
#include "CodeOrigin.h"
#include "CodeType.h"
#include "CompactJITCodeMap.h"
#include "DFGCodeBlocks.h"
#include "DFGCommon.h"
#include "DFGExitProfile.h"
#include "DFGMinifiedGraph.h"
#include "DFGOSREntry.h"
#include "DFGOSRExit.h"
#include "DFGVariableEventStream.h"
#include "EvalCodeCache.h"
#include "ExecutionCounter.h"
#include "ExpressionRangeInfo.h"
#include "HandlerInfo.h"
#include "ObjectAllocationProfile.h"
#include "Options.h"
#include "Instruction.h"
#include "JITCode.h"
#include "JITWriteBarrier.h"
#include "JSGlobalObject.h"
#include "JumpReplacementWatchpoint.h"
#include "JumpTable.h"
#include "LLIntCallLinkInfo.h"
#include "LazyOperandValueProfile.h"
#include "LineInfo.h"
#include "ProfilerCompilation.h"
#include "RegExpObject.h"
#include "ResolveOperation.h"
#include "StructureStubInfo.h"
#include "UnconditionalFinalizer.h"
#include "ValueProfile.h"
#include "Watchpoint.h"
#include <wtf/RefCountedArray.h>
#include <wtf/FastAllocBase.h>
#include <wtf/PassOwnPtr.h>
#include <wtf/Platform.h>
#include <wtf/RefPtr.h>
#include <wtf/SegmentedVector.h>
#include <wtf/Vector.h>
#include <wtf/text/WTFString.h>

namespace JSC {

class DFGCodeBlocks;
class ExecState;
class LLIntOffsetsExtractor;
class RepatchBuffer;

inline int unmodifiedArgumentsRegister(int argumentsRegister) { return argumentsRegister - 1; }

static ALWAYS_INLINE int missingThisObjectMarker() { return std::numeric_limits<int>::max(); }

class CodeBlock : public UnconditionalFinalizer, public WeakReferenceHarvester {
    WTF_MAKE_FAST_ALLOCATED;
    friend class JIT;
    friend class LLIntOffsetsExtractor;
public:
    enum CopyParsedBlockTag { CopyParsedBlock };
protected:
    CodeBlock(CopyParsedBlockTag, CodeBlock& other);
        
    CodeBlock(ScriptExecutable* ownerExecutable, UnlinkedCodeBlock*, JSGlobalObject*, unsigned baseScopeDepth, PassRefPtr<SourceProvider>, unsigned sourceOffset, unsigned firstLineColumnOffset, PassOwnPtr<CodeBlock> alternative);

    WriteBarrier<JSGlobalObject> m_globalObject;
    Heap* m_heap;

public:
    JS_EXPORT_PRIVATE virtual ~CodeBlock();
        
    UnlinkedCodeBlock* unlinkedCodeBlock() const { return m_unlinkedCode.get(); }
        
    String inferredName() const;
    CodeBlockHash hash() const;
    String sourceCodeForTools() const; // Not quite the actual source we parsed; this will do things like prefix the source for a function with a reified signature.
    String sourceCodeOnOneLine() const; // As sourceCodeForTools(), but replaces all whitespace runs with a single space.
    void dumpAssumingJITType(PrintStream&, JITCode::JITType) const;
    void dump(PrintStream&) const;
        
    int numParameters() const { return m_numParameters; }
    void setNumParameters(int newValue);
        
    int* addressOfNumParameters() { return &m_numParameters; }
    static ptrdiff_t offsetOfNumParameters() { return OBJECT_OFFSETOF(CodeBlock, m_numParameters); }

    CodeBlock* alternative() { return m_alternative.get(); }
    PassOwnPtr<CodeBlock> releaseAlternative() { return m_alternative.release(); }
    void setAlternative(PassOwnPtr<CodeBlock> alternative) { m_alternative = alternative; }
        
    CodeSpecializationKind specializationKind() const
    {
        return specializationFromIsConstruct(m_isConstructor);
    }
        
#if ENABLE(JIT)
    CodeBlock* baselineVersion()
    {
        CodeBlock* result = replacement();
        if (!result)
            return 0; // This can happen if we're in the process of creating the baseline version.
        while (result->alternative())
            result = result->alternative();
        ASSERT(result);
        ASSERT(JITCode::isBaselineCode(result->getJITType()));
        return result;
    }
#else
    CodeBlock* baselineVersion()
    {
        return this;
    }
#endif

    void visitAggregate(SlotVisitor&);

    static void dumpStatistics();

    void dumpBytecode(PrintStream& = WTF::dataFile());
    void dumpBytecode(PrintStream&, unsigned bytecodeOffset);
    void printStructures(PrintStream&, const Instruction*);
    void printStructure(PrintStream&, const char* name, const Instruction*, int operand);

    bool isStrictMode() const { return m_isStrictMode; }

    inline bool isKnownNotImmediate(int index)
    {
        if (index == m_thisRegister && !m_isStrictMode)
            return true;

        if (isConstantRegisterIndex(index))
            return getConstant(index).isCell();

        return false;
    }

    ALWAYS_INLINE bool isTemporaryRegisterIndex(int index)
    {
        return index >= m_numVars;
    }

    HandlerInfo* handlerForBytecodeOffset(unsigned bytecodeOffset);
    unsigned lineNumberForBytecodeOffset(unsigned bytecodeOffset);
    unsigned columnNumberForBytecodeOffset(unsigned bytecodeOffset);
    void expressionRangeForBytecodeOffset(unsigned bytecodeOffset, int& divot,
        int& startOffset, int& endOffset, unsigned& line, unsigned& column);

#if ENABLE(JIT)

    StructureStubInfo& getStubInfo(ReturnAddressPtr returnAddress)
    {
        return *(binarySearch<StructureStubInfo, void*>(m_structureStubInfos, m_structureStubInfos.size(), returnAddress.value(), getStructureStubInfoReturnLocation));
    }

    StructureStubInfo& getStubInfo(unsigned bytecodeIndex)
    {
        return *(binarySearch<StructureStubInfo, unsigned>(m_structureStubInfos, m_structureStubInfos.size(), bytecodeIndex, getStructureStubInfoBytecodeIndex));
    }
        
    void resetStub(StructureStubInfo&);
        
    ByValInfo& getByValInfo(unsigned bytecodeIndex)
    {
        return *(binarySearch<ByValInfo, unsigned>(m_byValInfos, m_byValInfos.size(), bytecodeIndex, getByValInfoBytecodeIndex));
    }

    CallLinkInfo& getCallLinkInfo(ReturnAddressPtr returnAddress)
    {
        return *(binarySearch<CallLinkInfo, void*>(m_callLinkInfos, m_callLinkInfos.size(), returnAddress.value(), getCallLinkInfoReturnLocation));
    }
        
    CallLinkInfo& getCallLinkInfo(unsigned bytecodeIndex)
    {
        ASSERT(JITCode::isBaselineCode(getJITType()));
        return *(binarySearch<CallLinkInfo, unsigned>(m_callLinkInfos, m_callLinkInfos.size(), bytecodeIndex, getCallLinkInfoBytecodeIndex));
    }
#endif // ENABLE(JIT)

#if ENABLE(LLINT)
    Instruction* adjustPCIfAtCallSite(Instruction*);
#endif
    unsigned bytecodeOffset(ExecState*, ReturnAddressPtr);

#if ENABLE(JIT)
    unsigned bytecodeOffsetForCallAtIndex(unsigned index)
    {
        if (!m_rareData)
            return 1;
        Vector<CallReturnOffsetToBytecodeOffset, 0, UnsafeVectorOverflow>& callIndices = m_rareData->m_callReturnIndexVector;
        if (!callIndices.size())
            return 1;
        // FIXME: Fix places in DFG that call out to C that don't set the CodeOrigin. https://bugs.webkit.org/show_bug.cgi?id=118315 
        ASSERT(index < m_rareData->m_callReturnIndexVector.size());
        if (index >= m_rareData->m_callReturnIndexVector.size())
            return 1;
        return m_rareData->m_callReturnIndexVector[index].bytecodeOffset;
    }

    void unlinkCalls();
        
    bool hasIncomingCalls() { return m_incomingCalls.begin() != m_incomingCalls.end(); }
        
    void linkIncomingCall(CallLinkInfo* incoming)
    {
        m_incomingCalls.push(incoming);
    }
        
    bool isIncomingCallAlreadyLinked(CallLinkInfo* incoming)
    {
        return m_incomingCalls.isOnList(incoming);
    }
#endif // ENABLE(JIT)

#if ENABLE(LLINT)
    void linkIncomingCall(LLIntCallLinkInfo* incoming)
    {
        m_incomingLLIntCalls.push(incoming);
    }
#endif // ENABLE(LLINT)
        
    void unlinkIncomingCalls();

#if ENABLE(DFG_JIT) || ENABLE(LLINT)
    void setJITCodeMap(PassOwnPtr<CompactJITCodeMap> jitCodeMap)
    {
        m_jitCodeMap = jitCodeMap;
    }
    CompactJITCodeMap* jitCodeMap()
    {
        return m_jitCodeMap.get();
    }
#endif
        
#if ENABLE(DFG_JIT)
    void createDFGDataIfNecessary()
    {
        if (!!m_dfgData)
            return;
            
        m_dfgData = adoptPtr(new DFGData);
    }
        
    void saveCompilation(PassRefPtr<Profiler::Compilation> compilation)
    {
        createDFGDataIfNecessary();
        m_dfgData->compilation = compilation;
    }
        
    Profiler::Compilation* compilation()
    {
        if (!m_dfgData)
            return 0;
        return m_dfgData->compilation.get();
    }
        
    DFG::OSREntryData* appendDFGOSREntryData(unsigned bytecodeIndex, unsigned machineCodeOffset)
    {
        createDFGDataIfNecessary();
        DFG::OSREntryData entry;
        entry.m_bytecodeIndex = bytecodeIndex;
        entry.m_machineCodeOffset = machineCodeOffset;
        m_dfgData->osrEntry.append(entry);
        return &m_dfgData->osrEntry.last();
    }
    unsigned numberOfDFGOSREntries() const
    {
        if (!m_dfgData)
            return 0;
        return m_dfgData->osrEntry.size();
    }
    DFG::OSREntryData* dfgOSREntryData(unsigned i) { return &m_dfgData->osrEntry[i]; }
    DFG::OSREntryData* dfgOSREntryDataForBytecodeIndex(unsigned bytecodeIndex)
    {
        if (!m_dfgData)
            return 0;
        return tryBinarySearch<DFG::OSREntryData, unsigned>(
            m_dfgData->osrEntry, m_dfgData->osrEntry.size(), bytecodeIndex,
            DFG::getOSREntryDataBytecodeIndex);
    }
        
    unsigned appendOSRExit(const DFG::OSRExit& osrExit)
    {
        createDFGDataIfNecessary();
        unsigned result = m_dfgData->osrExit.size();
        m_dfgData->osrExit.append(osrExit);
        return result;
    }
        
    DFG::OSRExit& lastOSRExit()
    {
        return m_dfgData->osrExit.last();
    }
        
    unsigned appendSpeculationRecovery(const DFG::SpeculationRecovery& recovery)
    {
        createDFGDataIfNecessary();
        unsigned result = m_dfgData->speculationRecovery.size();
        m_dfgData->speculationRecovery.append(recovery);
        return result;
    }
        
    unsigned appendWatchpoint(const JumpReplacementWatchpoint& watchpoint)
    {
        createDFGDataIfNecessary();
        unsigned result = m_dfgData->watchpoints.size();
        m_dfgData->watchpoints.append(watchpoint);
        return result;
    }
        
    unsigned numberOfOSRExits()
    {
        if (!m_dfgData)
            return 0;
        return m_dfgData->osrExit.size();
    }
        
    unsigned numberOfSpeculationRecoveries()
    {
        if (!m_dfgData)
            return 0;
        return m_dfgData->speculationRecovery.size();
    }
        
    unsigned numberOfWatchpoints()
    {
        if (!m_dfgData)
            return 0;
        return m_dfgData->watchpoints.size();
    }
        
    DFG::OSRExit& osrExit(unsigned index)
    {
        return m_dfgData->osrExit[index];
    }
        
    DFG::SpeculationRecovery& speculationRecovery(unsigned index)
    {
        return m_dfgData->speculationRecovery[index];
    }
        
    JumpReplacementWatchpoint& watchpoint(unsigned index)
    {
        return m_dfgData->watchpoints[index];
    }
        
    void appendWeakReference(JSCell* target)
    {
        createDFGDataIfNecessary();
        m_dfgData->weakReferences.append(WriteBarrier<JSCell>(*vm(), ownerExecutable(), target));
    }
        
    void appendWeakReferenceTransition(JSCell* codeOrigin, JSCell* from, JSCell* to)
    {
        createDFGDataIfNecessary();
        m_dfgData->transitions.append(
            WeakReferenceTransition(*vm(), ownerExecutable(), codeOrigin, from, to));
    }
        
    DFG::MinifiedGraph& minifiedDFG()
    {
        createDFGDataIfNecessary();
        return m_dfgData->minifiedDFG;
    }
        
    DFG::VariableEventStream& variableEventStream()
    {
        createDFGDataIfNecessary();
        return m_dfgData->variableEventStream;
    }
#endif

    unsigned bytecodeOffset(Instruction* returnAddress)
    {
        RELEASE_ASSERT(returnAddress >= instructions().begin() && returnAddress < instructions().end());
        return static_cast<Instruction*>(returnAddress) - instructions().begin();
    }

    bool isNumericCompareFunction() { return m_unlinkedCode->isNumericCompareFunction(); }

    unsigned numberOfInstructions() const { return m_instructions.size(); }
    RefCountedArray<Instruction>& instructions() { return m_instructions; }
    const RefCountedArray<Instruction>& instructions() const { return m_instructions; }
        
    size_t predictedMachineCodeSize();
        
    bool usesOpcode(OpcodeID);

    unsigned instructionCount() { return m_instructions.size(); }

    int argumentIndexAfterCapture(size_t argument);

#if ENABLE(JIT)
    void setJITCode(const JITCode& code, MacroAssemblerCodePtr codeWithArityCheck)
    {
        m_jitCode = code;
        m_jitCodeWithArityCheck = codeWithArityCheck;
#if ENABLE(DFG_JIT)
        if (m_jitCode.jitType() == JITCode::DFGJIT) {
            createDFGDataIfNecessary();
            m_vm->heap.m_dfgCodeBlocks.m_set.add(this);
        }
#endif
    }
    JITCode& getJITCode() { return m_jitCode; }
    MacroAssemblerCodePtr getJITCodeWithArityCheck() { return m_jitCodeWithArityCheck; }
    JITCode::JITType getJITType() const { return m_jitCode.jitType(); }
    ExecutableMemoryHandle* executableMemory() { return getJITCode().getExecutableMemory(); }
    virtual JSObject* compileOptimized(ExecState*, JSScope*, unsigned bytecodeIndex) = 0;
    void jettison();
    enum JITCompilationResult { AlreadyCompiled, CouldNotCompile, CompiledSuccessfully };
    JITCompilationResult jitCompile(ExecState* exec)
    {
        if (getJITType() != JITCode::InterpreterThunk) {
            ASSERT(getJITType() == JITCode::BaselineJIT);
            return AlreadyCompiled;
        }
#if ENABLE(JIT)
        if (jitCompileImpl(exec))
            return CompiledSuccessfully;
        return CouldNotCompile;
#else
        UNUSED_PARAM(exec);
        return CouldNotCompile;
#endif
    }
    virtual CodeBlock* replacement() = 0;

    virtual DFG::CapabilityLevel canCompileWithDFGInternal() = 0;
    DFG::CapabilityLevel canCompileWithDFG()
    {
        DFG::CapabilityLevel result = canCompileWithDFGInternal();
        m_canCompileWithDFGState = result;
        return result;
    }
    DFG::CapabilityLevel canCompileWithDFGState() { return m_canCompileWithDFGState; }

    bool hasOptimizedReplacement()
    {
        ASSERT(JITCode::isBaselineCode(getJITType()));
        bool result = replacement()->getJITType() > getJITType();
#if !ASSERT_DISABLED
        if (result)
            ASSERT(replacement()->getJITType() == JITCode::DFGJIT);
        else {
            ASSERT(JITCode::isBaselineCode(replacement()->getJITType()));
            ASSERT(replacement() == this);
        }
#endif
        return result;
    }
#else
    JITCode::JITType getJITType() const { return JITCode::BaselineJIT; }
#endif

    ScriptExecutable* ownerExecutable() const { return m_ownerExecutable.get(); }

    void setVM(VM* vm) { m_vm = vm; }
    VM* vm() { return m_vm; }

    void setThisRegister(int thisRegister) { m_thisRegister = thisRegister; }
    int thisRegister() const { return m_thisRegister; }

    bool needsFullScopeChain() const { return m_unlinkedCode->needsFullScopeChain(); }
    bool usesEval() const { return m_unlinkedCode->usesEval(); }
        
    void setArgumentsRegister(int argumentsRegister)
    {
        ASSERT(argumentsRegister != -1);
        m_argumentsRegister = argumentsRegister;
        ASSERT(usesArguments());
    }
    int argumentsRegister() const
    {
        ASSERT(usesArguments());
        return m_argumentsRegister;
    }
    int uncheckedArgumentsRegister()
    {
        if (!usesArguments())
            return InvalidVirtualRegister;
        return argumentsRegister();
    }
    void setActivationRegister(int activationRegister)
    {
        m_activationRegister = activationRegister;
    }
    int activationRegister() const
    {
        ASSERT(needsFullScopeChain());
        return m_activationRegister;
    }
    int uncheckedActivationRegister()
    {
        if (!needsFullScopeChain())
            return InvalidVirtualRegister;
        return activationRegister();
    }
    bool usesArguments() const { return m_argumentsRegister != -1; }
        
    bool needsActivation() const
    {
        return needsFullScopeChain() && codeType() != GlobalCode;
    }

    bool isCaptured(int operand, InlineCallFrame* inlineCallFrame = 0) const
    {
        if (operandIsArgument(operand))
            return operandToArgument(operand) && usesArguments();

        if (inlineCallFrame)
            return inlineCallFrame->capturedVars.get(operand);

        // The activation object isn't in the captured region, but it's "captured"
        // in the sense that stores to its location can be observed indirectly.
        if (needsActivation() && operand == activationRegister())
            return true;

        // Ditto for the arguments object.
        if (usesArguments() && operand == argumentsRegister())
            return true;

        // Ditto for the arguments object.
        if (usesArguments() && operand == unmodifiedArgumentsRegister(argumentsRegister()))
            return true;

        // We're in global code so there are no locals to capture
        if (!symbolTable())
            return false;

        return operand >= symbolTable()->captureStart()
            && operand < symbolTable()->captureEnd();
    }

    CodeType codeType() const { return m_unlinkedCode->codeType(); }

    SourceProvider* source() const { return m_source.get(); }
    unsigned sourceOffset() const { return m_sourceOffset; }
    unsigned firstLineColumnOffset() const { return m_firstLineColumnOffset; }

    size_t numberOfJumpTargets() const { return m_unlinkedCode->numberOfJumpTargets(); }
    unsigned jumpTarget(int index) const { return m_unlinkedCode->jumpTarget(index); }

    void createActivation(CallFrame*);

    void clearEvalCache();
        
    String nameForRegister(int registerNumber);

#if ENABLE(JIT)
    void setNumberOfStructureStubInfos(size_t size) { m_structureStubInfos.grow(size); }
    size_t numberOfStructureStubInfos() const { return m_structureStubInfos.size(); }
    StructureStubInfo& structureStubInfo(int index) { return m_structureStubInfos[index]; }
        
    void setNumberOfByValInfos(size_t size) { m_byValInfos.grow(size); }
    size_t numberOfByValInfos() const { return m_byValInfos.size(); }
    ByValInfo& byValInfo(size_t index) { return m_byValInfos[index]; }

    void setNumberOfCallLinkInfos(size_t size) { m_callLinkInfos.grow(size); }
    size_t numberOfCallLinkInfos() const { return m_callLinkInfos.size(); }
    CallLinkInfo& callLinkInfo(int index) { return m_callLinkInfos[index]; }
#endif
        
#if ENABLE(VALUE_PROFILER)
    unsigned numberOfArgumentValueProfiles()
    {
        ASSERT(m_numParameters >= 0);
        ASSERT(m_argumentValueProfiles.size() == static_cast<unsigned>(m_numParameters));
        return m_argumentValueProfiles.size();
    }
    ValueProfile* valueProfileForArgument(unsigned argumentIndex)
    {
        ValueProfile* result = &m_argumentValueProfiles[argumentIndex];
        ASSERT(result->m_bytecodeOffset == -1);
        return result;
    }

    unsigned numberOfValueProfiles() { return m_valueProfiles.size(); }
    ValueProfile* valueProfile(int index) { return &m_valueProfiles[index]; }
    ValueProfile* valueProfileForBytecodeOffset(int bytecodeOffset)
    {
        ValueProfile* result = binarySearch<ValueProfile, int>(
            m_valueProfiles, m_valueProfiles.size(), bytecodeOffset,
            getValueProfileBytecodeOffset<ValueProfile>);
        ASSERT(result->m_bytecodeOffset != -1);
        ASSERT(instructions()[bytecodeOffset + opcodeLength(
            m_vm->interpreter->getOpcodeID(
                instructions()[
                    bytecodeOffset].u.opcode)) - 1].u.profile == result);
        return result;
    }
    SpeculatedType valueProfilePredictionForBytecodeOffset(int bytecodeOffset)
    {
        return valueProfileForBytecodeOffset(bytecodeOffset)->computeUpdatedPrediction();
    }
        
    unsigned totalNumberOfValueProfiles()
    {
        return numberOfArgumentValueProfiles() + numberOfValueProfiles();
    }
    ValueProfile* getFromAllValueProfiles(unsigned index)
    {
        if (index < numberOfArgumentValueProfiles())
            return valueProfileForArgument(index);
        return valueProfile(index - numberOfArgumentValueProfiles());
    }
        
    RareCaseProfile* addRareCaseProfile(int bytecodeOffset)
    {
        m_rareCaseProfiles.append(RareCaseProfile(bytecodeOffset));
        return &m_rareCaseProfiles.last();
    }
    unsigned numberOfRareCaseProfiles() { return m_rareCaseProfiles.size(); }
    RareCaseProfile* rareCaseProfile(int index) { return &m_rareCaseProfiles[index]; }
    RareCaseProfile* rareCaseProfileForBytecodeOffset(int bytecodeOffset)
    {
        return tryBinarySearch<RareCaseProfile, int>(
            m_rareCaseProfiles, m_rareCaseProfiles.size(), bytecodeOffset,
            getRareCaseProfileBytecodeOffset);
    }
        
    bool likelyToTakeSlowCase(int bytecodeOffset)
    {
        if (!numberOfRareCaseProfiles())
            return false;
        unsigned value = rareCaseProfileForBytecodeOffset(bytecodeOffset)->m_counter;
        return value >= Options::likelyToTakeSlowCaseMinimumCount();
    }
        
    bool couldTakeSlowCase(int bytecodeOffset)
    {
        if (!numberOfRareCaseProfiles())
            return false;
        unsigned value = rareCaseProfileForBytecodeOffset(bytecodeOffset)->m_counter;
        return value >= Options::couldTakeSlowCaseMinimumCount();
    }
        
    RareCaseProfile* addSpecialFastCaseProfile(int bytecodeOffset)
    {
        m_specialFastCaseProfiles.append(RareCaseProfile(bytecodeOffset));
        return &m_specialFastCaseProfiles.last();
    }
    unsigned numberOfSpecialFastCaseProfiles() { return m_specialFastCaseProfiles.size(); }
    RareCaseProfile* specialFastCaseProfile(int index) { return &m_specialFastCaseProfiles[index]; }
    RareCaseProfile* specialFastCaseProfileForBytecodeOffset(int bytecodeOffset)
    {
        return tryBinarySearch<RareCaseProfile, int>(
            m_specialFastCaseProfiles, m_specialFastCaseProfiles.size(), bytecodeOffset,
            getRareCaseProfileBytecodeOffset);
    }
        
    bool likelyToTakeSpecialFastCase(int bytecodeOffset)
    {
        if (!numberOfRareCaseProfiles())
            return false;
        unsigned specialFastCaseCount = specialFastCaseProfileForBytecodeOffset(bytecodeOffset)->m_counter;
        return specialFastCaseCount >= Options::likelyToTakeSlowCaseMinimumCount();
    }
        
    bool couldTakeSpecialFastCase(int bytecodeOffset)
    {
        if (!numberOfRareCaseProfiles())
            return false;
        unsigned specialFastCaseCount = specialFastCaseProfileForBytecodeOffset(bytecodeOffset)->m_counter;
        return specialFastCaseCount >= Options::couldTakeSlowCaseMinimumCount();
    }
        
    bool likelyToTakeDeepestSlowCase(int bytecodeOffset)
    {
        if (!numberOfRareCaseProfiles())
            return false;
        unsigned slowCaseCount = rareCaseProfileForBytecodeOffset(bytecodeOffset)->m_counter;
        unsigned specialFastCaseCount = specialFastCaseProfileForBytecodeOffset(bytecodeOffset)->m_counter;
        unsigned value = slowCaseCount - specialFastCaseCount;
        return value >= Options::likelyToTakeSlowCaseMinimumCount();
    }
        
    bool likelyToTakeAnySlowCase(int bytecodeOffset)
    {
        if (!numberOfRareCaseProfiles())
            return false;
        unsigned slowCaseCount = rareCaseProfileForBytecodeOffset(bytecodeOffset)->m_counter;
        unsigned specialFastCaseCount = specialFastCaseProfileForBytecodeOffset(bytecodeOffset)->m_counter;
        unsigned value = slowCaseCount + specialFastCaseCount;
        return value >= Options::likelyToTakeSlowCaseMinimumCount();
    }
        
    unsigned numberOfArrayProfiles() const { return m_arrayProfiles.size(); }
    const ArrayProfileVector& arrayProfiles() { return m_arrayProfiles; }
    ArrayProfile* addArrayProfile(unsigned bytecodeOffset)
    {
        m_arrayProfiles.append(ArrayProfile(bytecodeOffset));
        return &m_arrayProfiles.last();
    }
    ArrayProfile* getArrayProfile(unsigned bytecodeOffset);
    ArrayProfile* getOrAddArrayProfile(unsigned bytecodeOffset);
#endif

    // Exception handling support

    size_t numberOfExceptionHandlers() const { return m_rareData ? m_rareData->m_exceptionHandlers.size() : 0; }
    void allocateHandlers(const Vector<UnlinkedHandlerInfo>& unlinkedHandlers)
    {
        size_t count = unlinkedHandlers.size();
        if (!count)
            return;
        createRareDataIfNecessary();
        m_rareData->m_exceptionHandlers.resize(count);
        for (size_t i = 0; i < count; ++i) {
            m_rareData->m_exceptionHandlers[i].start = unlinkedHandlers[i].start;
            m_rareData->m_exceptionHandlers[i].end = unlinkedHandlers[i].end;
            m_rareData->m_exceptionHandlers[i].target = unlinkedHandlers[i].target;
            m_rareData->m_exceptionHandlers[i].scopeDepth = unlinkedHandlers[i].scopeDepth;
        }

    }
    HandlerInfo& exceptionHandler(int index) { RELEASE_ASSERT(m_rareData); return m_rareData->m_exceptionHandlers[index]; }

    bool hasExpressionInfo() { return m_unlinkedCode->hasExpressionInfo(); }

#if ENABLE(JIT)
    Vector<CallReturnOffsetToBytecodeOffset, 0, UnsafeVectorOverflow>& callReturnIndexVector()
    {
        createRareDataIfNecessary();
        return m_rareData->m_callReturnIndexVector;
    }
#endif

#if ENABLE(DFG_JIT)
    SegmentedVector<InlineCallFrame, 4>& inlineCallFrames()
    {
        createRareDataIfNecessary();
        return m_rareData->m_inlineCallFrames;
    }
        
    Vector<CodeOriginAtCallReturnOffset, 0, UnsafeVectorOverflow>& codeOrigins()
    {
        createRareDataIfNecessary();
        return m_rareData->m_codeOrigins;
    }
        
    // Having code origins implies that there has been some inlining.
    bool hasCodeOrigins()
    {
        return m_rareData && !!m_rareData->m_codeOrigins.size();
    }
        
    bool codeOriginForReturn(ReturnAddressPtr, CodeOrigin&);
        
    bool canGetCodeOrigin(unsigned index)
    {
        if (!m_rareData)
            return false;
        return m_rareData->m_codeOrigins.size() > index;
    }
        
    CodeOrigin codeOrigin(unsigned index)
    {
        RELEASE_ASSERT(m_rareData);
        return m_rareData->m_codeOrigins[index].codeOrigin;
    }
        
    bool addFrequentExitSite(const DFG::FrequentExitSite& site)
    {
        ASSERT(JITCode::isBaselineCode(getJITType()));
        return m_exitProfile.add(site);
    }
        
    bool hasExitSite(const DFG::FrequentExitSite& site) const { return m_exitProfile.hasExitSite(site); }

    DFG::ExitProfile& exitProfile() { return m_exitProfile; }
        
    CompressedLazyOperandValueProfileHolder& lazyOperandValueProfiles()
    {
        return m_lazyOperandValueProfiles;
    }
#endif

    // Constant Pool

    size_t numberOfIdentifiers() const { return m_identifiers.size(); }
    void addIdentifier(const Identifier& i) { return m_identifiers.append(i); }
    Identifier& identifier(int index) { return m_identifiers[index]; }

    size_t numberOfConstantRegisters() const { return m_constantRegisters.size(); }
    unsigned addConstant(JSValue v)
    {
        unsigned result = m_constantRegisters.size();
        m_constantRegisters.append(WriteBarrier<Unknown>());
        m_constantRegisters.last().set(m_globalObject->vm(), m_ownerExecutable.get(), v);
        return result;
    }


    unsigned addOrFindConstant(JSValue);
    WriteBarrier<Unknown>& constantRegister(int index) { return m_constantRegisters[index - FirstConstantRegisterIndex]; }
    ALWAYS_INLINE bool isConstantRegisterIndex(int index) const { return index >= FirstConstantRegisterIndex; }
    ALWAYS_INLINE JSValue getConstant(int index) const { return m_constantRegisters[index - FirstConstantRegisterIndex].get(); }

    FunctionExecutable* functionDecl(int index) { return m_functionDecls[index].get(); }
    int numberOfFunctionDecls() { return m_functionDecls.size(); }
    FunctionExecutable* functionExpr(int index) { return m_functionExprs[index].get(); }

    RegExp* regexp(int index) const { return m_unlinkedCode->regexp(index); }

    unsigned numberOfConstantBuffers() const
    {
        if (!m_rareData)
            return 0;
        return m_rareData->m_constantBuffers.size();
    }
    unsigned addConstantBuffer(const Vector<JSValue>& buffer)
    {
        createRareDataIfNecessary();
        unsigned size = m_rareData->m_constantBuffers.size();
        m_rareData->m_constantBuffers.append(buffer);
        return size;
    }

    Vector<JSValue>& constantBufferAsVector(unsigned index)
    {
        ASSERT(m_rareData);
        return m_rareData->m_constantBuffers[index];
    }
    JSValue* constantBuffer(unsigned index)
    {
        return constantBufferAsVector(index).data();
    }

    JSGlobalObject* globalObject() { return m_globalObject.get(); }
        
    JSGlobalObject* globalObjectFor(CodeOrigin);

    // Jump Tables

    size_t numberOfImmediateSwitchJumpTables() const { return m_rareData ? m_rareData->m_immediateSwitchJumpTables.size() : 0; }
    SimpleJumpTable& addImmediateSwitchJumpTable() { createRareDataIfNecessary(); m_rareData->m_immediateSwitchJumpTables.append(SimpleJumpTable()); return m_rareData->m_immediateSwitchJumpTables.last(); }
    SimpleJumpTable& immediateSwitchJumpTable(int tableIndex) { RELEASE_ASSERT(m_rareData); return m_rareData->m_immediateSwitchJumpTables[tableIndex]; }

    size_t numberOfCharacterSwitchJumpTables() const { return m_rareData ? m_rareData->m_characterSwitchJumpTables.size() : 0; }
    SimpleJumpTable& addCharacterSwitchJumpTable() { createRareDataIfNecessary(); m_rareData->m_characterSwitchJumpTables.append(SimpleJumpTable()); return m_rareData->m_characterSwitchJumpTables.last(); }
    SimpleJumpTable& characterSwitchJumpTable(int tableIndex) { RELEASE_ASSERT(m_rareData); return m_rareData->m_characterSwitchJumpTables[tableIndex]; }

    size_t numberOfStringSwitchJumpTables() const { return m_rareData ? m_rareData->m_stringSwitchJumpTables.size() : 0; }
    StringJumpTable& addStringSwitchJumpTable() { createRareDataIfNecessary(); m_rareData->m_stringSwitchJumpTables.append(StringJumpTable()); return m_rareData->m_stringSwitchJumpTables.last(); }
    StringJumpTable& stringSwitchJumpTable(int tableIndex) { RELEASE_ASSERT(m_rareData); return m_rareData->m_stringSwitchJumpTables[tableIndex]; }


    SharedSymbolTable* symbolTable() const { return m_unlinkedCode->symbolTable(); }

    EvalCodeCache& evalCodeCache() { createRareDataIfNecessary(); return m_rareData->m_evalCodeCache; }

    enum ShrinkMode {
        // Shrink prior to generating machine code that may point directly into vectors.
        EarlyShrink,
            
        // Shrink after generating machine code, and after possibly creating new vectors
        // and appending to others. At this time it is not safe to shrink certain vectors
        // because we would have generated machine code that references them directly.
        LateShrink
    };
    void shrinkToFit(ShrinkMode);
        
    void copyPostParseDataFrom(CodeBlock* alternative);
    void copyPostParseDataFromAlternative();
        
    // Functions for controlling when JITting kicks in, in a mixed mode
    // execution world.
        
    bool checkIfJITThresholdReached()
    {
        return m_llintExecuteCounter.checkIfThresholdCrossedAndSet(this);
    }
        
    void dontJITAnytimeSoon()
    {
        m_llintExecuteCounter.deferIndefinitely();
    }
        
    void jitAfterWarmUp()
    {
        m_llintExecuteCounter.setNewThreshold(Options::thresholdForJITAfterWarmUp(), this);
    }
        
    void jitSoon()
    {
        m_llintExecuteCounter.setNewThreshold(Options::thresholdForJITSoon(), this);
    }
        
    const ExecutionCounter& llintExecuteCounter() const
    {
        return m_llintExecuteCounter;
    }
        
    // Functions for controlling when tiered compilation kicks in. This
    // controls both when the optimizing compiler is invoked and when OSR
    // entry happens. Two triggers exist: the loop trigger and the return
    // trigger. In either case, when an addition to m_jitExecuteCounter
    // causes it to become non-negative, the optimizing compiler is
    // invoked. This includes a fast check to see if this CodeBlock has
    // already been optimized (i.e. replacement() returns a CodeBlock
    // that was optimized with a higher tier JIT than this one). In the
    // case of the loop trigger, if the optimized compilation succeeds
    // (or has already succeeded in the past) then OSR is attempted to
    // redirect program flow into the optimized code.
        
    // These functions are called from within the optimization triggers,
    // and are used as a single point at which we define the heuristics
    // for how much warm-up is mandated before the next optimization
    // trigger files. All CodeBlocks start out with optimizeAfterWarmUp(),
    // as this is called from the CodeBlock constructor.
        
    // When we observe a lot of speculation failures, we trigger a
    // reoptimization. But each time, we increase the optimization trigger
    // to avoid thrashing.
    unsigned reoptimizationRetryCounter() const;
    void countReoptimization();

    int32_t codeTypeThresholdMultiplier() const;
        
    int32_t counterValueForOptimizeAfterWarmUp();
    int32_t counterValueForOptimizeAfterLongWarmUp();
    int32_t counterValueForOptimizeSoon();
        
    int32_t* addressOfJITExecuteCounter()
    {
        return &m_jitExecuteCounter.m_counter;
    }
        
    static ptrdiff_t offsetOfJITExecuteCounter() { return OBJECT_OFFSETOF(CodeBlock, m_jitExecuteCounter) + OBJECT_OFFSETOF(ExecutionCounter, m_counter); }
    static ptrdiff_t offsetOfJITExecutionActiveThreshold() { return OBJECT_OFFSETOF(CodeBlock, m_jitExecuteCounter) + OBJECT_OFFSETOF(ExecutionCounter, m_activeThreshold); }
    static ptrdiff_t offsetOfJITExecutionTotalCount() { return OBJECT_OFFSETOF(CodeBlock, m_jitExecuteCounter) + OBJECT_OFFSETOF(ExecutionCounter, m_totalCount); }

    const ExecutionCounter& jitExecuteCounter() const { return m_jitExecuteCounter; }
        
    unsigned optimizationDelayCounter() const { return m_optimizationDelayCounter; }
        
    // Check if the optimization threshold has been reached, and if not,
    // adjust the heuristics accordingly. Returns true if the threshold has
    // been reached.
    bool checkIfOptimizationThresholdReached();
        
    // Call this to force the next optimization trigger to fire. This is
    // rarely wise, since optimization triggers are typically more
    // expensive than executing baseline code.
    void optimizeNextInvocation();
        
    // Call this to prevent optimization from happening again. Note that
    // optimization will still happen after roughly 2^29 invocations,
    // so this is really meant to delay that as much as possible. This
    // is called if optimization failed, and we expect it to fail in
    // the future as well.
    void dontOptimizeAnytimeSoon();
        
    // Call this to reinitialize the counter to its starting state,
    // forcing a warm-up to happen before the next optimization trigger
    // fires. This is called in the CodeBlock constructor. It also
    // makes sense to call this if an OSR exit occurred. Note that
    // OSR exit code is code generated, so the value of the execute
    // counter that this corresponds to is also available directly.
    void optimizeAfterWarmUp();
        
    // Call this to force an optimization trigger to fire only after
    // a lot of warm-up.
    void optimizeAfterLongWarmUp();
        
    // Call this to cause an optimization trigger to fire soon, but
    // not necessarily the next one. This makes sense if optimization
    // succeeds. Successfuly optimization means that all calls are
    // relinked to the optimized code, so this only affects call
    // frames that are still executing this CodeBlock. The value here
    // is tuned to strike a balance between the cost of OSR entry
    // (which is too high to warrant making every loop back edge to
    // trigger OSR immediately) and the cost of executing baseline
    // code (which is high enough that we don't necessarily want to
    // have a full warm-up). The intuition for calling this instead of
    // optimizeNextInvocation() is for the case of recursive functions
    // with loops. Consider that there may be N call frames of some
    // recursive function, for a reasonably large value of N. The top
    // one triggers optimization, and then returns, and then all of
    // the others return. We don't want optimization to be triggered on
    // each return, as that would be superfluous. It only makes sense
    // to trigger optimization if one of those functions becomes hot
    // in the baseline code.
    void optimizeSoon();
        
    uint32_t osrExitCounter() const { return m_osrExitCounter; }
        
    void countOSRExit() { m_osrExitCounter++; }
        
    uint32_t* addressOfOSRExitCounter() { return &m_osrExitCounter; }
        
    static ptrdiff_t offsetOfOSRExitCounter() { return OBJECT_OFFSETOF(CodeBlock, m_osrExitCounter); }

#if ENABLE(JIT)
    uint32_t adjustedExitCountThreshold(uint32_t desiredThreshold);
    uint32_t exitCountThresholdForReoptimization();
    uint32_t exitCountThresholdForReoptimizationFromLoop();
    bool shouldReoptimizeNow();
    bool shouldReoptimizeFromLoopNow();
#endif

#if ENABLE(VALUE_PROFILER)
    bool shouldOptimizeNow();
    void updateAllValueProfilePredictions(OperationInProgress = NoOperation);
    void updateAllArrayPredictions(OperationInProgress = NoOperation);
    void updateAllPredictions(OperationInProgress = NoOperation);
#else
    bool shouldOptimizeNow() { return false; }
    void updateAllValueProfilePredictions(OperationInProgress = NoOperation) { }
    void updateAllArrayPredictions(OperationInProgress = NoOperation) { }
    void updateAllPredictions(OperationInProgress = NoOperation) { }
#endif
        
#if ENABLE(JIT)
    void reoptimize();
#endif

#if ENABLE(VERBOSE_VALUE_PROFILE)
    void dumpValueProfiles();
#endif
        
    // FIXME: Make these remaining members private.

    int m_numCalleeRegisters;
    int m_numVars;
    bool m_isConstructor;

protected:
#if ENABLE(JIT)
    virtual bool jitCompileImpl(ExecState*) = 0;
    virtual void jettisonImpl() = 0;
#endif
    virtual void visitWeakReferences(SlotVisitor&);
    virtual void finalizeUnconditionally();

#if ENABLE(DFG_JIT)
    void tallyFrequentExitSites();
#else
    void tallyFrequentExitSites() { }
#endif

private:
    friend class DFGCodeBlocks;
        
    double optimizationThresholdScalingFactor();

#if ENABLE(JIT)
    ClosureCallStubRoutine* findClosureCallForReturnPC(ReturnAddressPtr);
#endif
        
#if ENABLE(VALUE_PROFILER)
    void updateAllPredictionsAndCountLiveness(OperationInProgress, unsigned& numberOfLiveNonArgumentValueProfiles, unsigned& numberOfSamplesInProfiles);
#endif

    void setIdentifiers(const Vector<Identifier>& identifiers)
    {
        RELEASE_ASSERT(m_identifiers.isEmpty());
        m_identifiers.appendVector(identifiers);
    }

    void setConstantRegisters(const Vector<WriteBarrier<Unknown> >& constants)
    {
        size_t count = constants.size();
        m_constantRegisters.resize(count);
        for (size_t i = 0; i < count; i++)
            m_constantRegisters[i].set(*m_vm, ownerExecutable(), constants[i].get());
    }

    void dumpBytecode(PrintStream&, ExecState*, const Instruction* begin, const Instruction*&);

    CString registerName(ExecState*, int r) const;
    void printUnaryOp(PrintStream&, ExecState*, int location, const Instruction*&, const char* op);
    void printBinaryOp(PrintStream&, ExecState*, int location, const Instruction*&, const char* op);
    void printConditionalJump(PrintStream&, ExecState*, const Instruction*, const Instruction*&, int location, const char* op);
    void printGetByIdOp(PrintStream&, ExecState*, int location, const Instruction*&);
    void printGetByIdCacheStatus(PrintStream&, ExecState*, int location);
    enum CacheDumpMode { DumpCaches, DontDumpCaches };
    void printCallOp(PrintStream&, ExecState*, int location, const Instruction*&, const char* op, CacheDumpMode);
    void printPutByIdOp(PrintStream&, ExecState*, int location, const Instruction*&, const char* op);
    void beginDumpProfiling(PrintStream&, bool& hasPrintedProfiling);
    void dumpValueProfiling(PrintStream&, const Instruction*&, bool& hasPrintedProfiling);
    void dumpArrayProfiling(PrintStream&, const Instruction*&, bool& hasPrintedProfiling);
#if ENABLE(VALUE_PROFILER)
    void dumpRareCaseProfile(PrintStream&, const char* name, RareCaseProfile*, bool& hasPrintedProfiling);
#endif

    void visitStructures(SlotVisitor&, Instruction* vPC);
        
#if ENABLE(DFG_JIT)
    bool shouldImmediatelyAssumeLivenessDuringScan()
    {
        // Null m_dfgData means that this is a baseline JIT CodeBlock. Baseline JIT
        // CodeBlocks don't need to be jettisoned when their weak references go
        // stale. So if a basline JIT CodeBlock gets scanned, we can assume that
        // this means that it's live.
        if (!m_dfgData)
            return true;
            
        // For simplicity, we don't attempt to jettison code blocks during GC if
        // they are executing. Instead we strongly mark their weak references to
        // allow them to continue to execute soundly.
        if (m_dfgData->mayBeExecuting)
            return true;
            
        if (Options::forceDFGCodeBlockLiveness())
            return true;

        return false;
    }
#else
    bool shouldImmediatelyAssumeLivenessDuringScan() { return true; }
#endif
        
    void performTracingFixpointIteration(SlotVisitor&);
        
    void stronglyVisitStrongReferences(SlotVisitor&);
    void stronglyVisitWeakReferences(SlotVisitor&);

    void createRareDataIfNecessary()
    {
        if (!m_rareData)
            m_rareData = adoptPtr(new RareData);
    }

#if ENABLE(JIT)
    void resetStubInternal(RepatchBuffer&, StructureStubInfo&);
    void resetStubDuringGCInternal(RepatchBuffer&, StructureStubInfo&);
#endif
    WriteBarrier<UnlinkedCodeBlock> m_unlinkedCode;
    int m_numParameters;
    WriteBarrier<ScriptExecutable> m_ownerExecutable;
    VM* m_vm;

    RefCountedArray<Instruction> m_instructions;
    int m_thisRegister;
    int m_argumentsRegister;
    int m_activationRegister;

    bool m_isStrictMode;
    bool m_needsActivation;

    RefPtr<SourceProvider> m_source;
    unsigned m_sourceOffset;
    unsigned m_firstLineColumnOffset;
    unsigned m_codeType;

#if ENABLE(LLINT)
    SegmentedVector<LLIntCallLinkInfo, 8> m_llintCallLinkInfos;
    SentinelLinkedList<LLIntCallLinkInfo, BasicRawSentinelNode<LLIntCallLinkInfo> > m_incomingLLIntCalls;
#endif
#if ENABLE(JIT)
    Vector<StructureStubInfo> m_structureStubInfos;
    Vector<ByValInfo> m_byValInfos;
    Vector<CallLinkInfo> m_callLinkInfos;
    JITCode m_jitCode;
    MacroAssemblerCodePtr m_jitCodeWithArityCheck;
    SentinelLinkedList<CallLinkInfo, BasicRawSentinelNode<CallLinkInfo> > m_incomingCalls;
#endif
#if ENABLE(DFG_JIT) || ENABLE(LLINT)
    OwnPtr<CompactJITCodeMap> m_jitCodeMap;
#endif
#if ENABLE(DFG_JIT)
    struct WeakReferenceTransition {
        WeakReferenceTransition() { }
            
        WeakReferenceTransition(VM& vm, JSCell* owner, JSCell* codeOrigin, JSCell* from, JSCell* to)
            : m_from(vm, owner, from)
            , m_to(vm, owner, to)
        {
            if (!!codeOrigin)
                m_codeOrigin.set(vm, owner, codeOrigin);
        }

        WriteBarrier<JSCell> m_codeOrigin;
        WriteBarrier<JSCell> m_from;
        WriteBarrier<JSCell> m_to;
    };
        
    struct DFGData {
        DFGData()
            : mayBeExecuting(false)
            , isJettisoned(false)
        {
        }
            
        Vector<DFG::OSREntryData> osrEntry;
        SegmentedVector<DFG::OSRExit, 8> osrExit;
        Vector<DFG::SpeculationRecovery> speculationRecovery;
        SegmentedVector<JumpReplacementWatchpoint, 1, 0> watchpoints;
        Vector<WeakReferenceTransition> transitions;
        Vector<WriteBarrier<JSCell> > weakReferences;
        DFG::VariableEventStream variableEventStream;
        DFG::MinifiedGraph minifiedDFG;
        RefPtr<Profiler::Compilation> compilation;
        bool mayBeExecuting;
        bool isJettisoned;
        bool livenessHasBeenProved; // Initialized and used on every GC.
        bool allTransitionsHaveBeenMarked; // Initialized and used on every GC.
        unsigned visitAggregateHasBeenCalled; // Unsigned to make it work seamlessly with the broadest set of CAS implementations.
    };
        
    OwnPtr<DFGData> m_dfgData;
        
    // This is relevant to non-DFG code blocks that serve as the profiled code block
    // for DFG code blocks.
    DFG::ExitProfile m_exitProfile;
    CompressedLazyOperandValueProfileHolder m_lazyOperandValueProfiles;
#endif
#if ENABLE(VALUE_PROFILER)
    Vector<ValueProfile> m_argumentValueProfiles;
    SegmentedVector<ValueProfile, 8> m_valueProfiles;
    SegmentedVector<RareCaseProfile, 8> m_rareCaseProfiles;
    SegmentedVector<RareCaseProfile, 8> m_specialFastCaseProfiles;
    SegmentedVector<ArrayAllocationProfile, 8> m_arrayAllocationProfiles;
    ArrayProfileVector m_arrayProfiles;
#endif
    SegmentedVector<ObjectAllocationProfile, 8> m_objectAllocationProfiles;

    // Constant Pool
    Vector<Identifier> m_identifiers;
    COMPILE_ASSERT(sizeof(Register) == sizeof(WriteBarrier<Unknown>), Register_must_be_same_size_as_WriteBarrier_Unknown);
    // TODO: This could just be a pointer to m_unlinkedCodeBlock's data, but the DFG mutates
    // it, so we're stuck with it for now.
    Vector<WriteBarrier<Unknown> > m_constantRegisters;
    Vector<WriteBarrier<FunctionExecutable> > m_functionDecls;
    Vector<WriteBarrier<FunctionExecutable> > m_functionExprs;

    OwnPtr<CodeBlock> m_alternative;
        
    ExecutionCounter m_llintExecuteCounter;
        
    ExecutionCounter m_jitExecuteCounter;
    int32_t m_totalJITExecutions;
    uint32_t m_osrExitCounter;
    uint16_t m_optimizationDelayCounter;
    uint16_t m_reoptimizationRetryCounter;

    Vector<ResolveOperations> m_resolveOperations;
    Vector<PutToBaseOperation, 1> m_putToBaseOperations;

    struct RareData {
        WTF_MAKE_FAST_ALLOCATED;
    public:
        Vector<HandlerInfo> m_exceptionHandlers;

        // Buffers used for large array literals
        Vector<Vector<JSValue> > m_constantBuffers;
            
        // Jump Tables
        Vector<SimpleJumpTable> m_immediateSwitchJumpTables;
        Vector<SimpleJumpTable> m_characterSwitchJumpTables;
        Vector<StringJumpTable> m_stringSwitchJumpTables;

        EvalCodeCache m_evalCodeCache;

#if ENABLE(JIT)
        Vector<CallReturnOffsetToBytecodeOffset, 0, UnsafeVectorOverflow> m_callReturnIndexVector;
#endif
#if ENABLE(DFG_JIT)
        SegmentedVector<InlineCallFrame, 4> m_inlineCallFrames;
        Vector<CodeOriginAtCallReturnOffset, 0, UnsafeVectorOverflow> m_codeOrigins;
#endif
    };
#if COMPILER(MSVC)
    friend void WTF::deleteOwnedPtr<RareData>(RareData*);
#endif
    OwnPtr<RareData> m_rareData;
#if ENABLE(JIT)
    DFG::CapabilityLevel m_canCompileWithDFGState;
#endif
};

// Program code is not marked by any function, so we make the global object
// responsible for marking it.

class GlobalCodeBlock : public CodeBlock {
protected:
    GlobalCodeBlock(CopyParsedBlockTag, GlobalCodeBlock& other)
        : CodeBlock(CopyParsedBlock, other)
    {
    }
        
    GlobalCodeBlock(ScriptExecutable* ownerExecutable, UnlinkedCodeBlock* unlinkedCodeBlock, JSGlobalObject* globalObject, unsigned baseScopeDepth, PassRefPtr<SourceProvider> sourceProvider, unsigned sourceOffset, unsigned firstLineColumnOffset, PassOwnPtr<CodeBlock> alternative)
        : CodeBlock(ownerExecutable, unlinkedCodeBlock, globalObject, baseScopeDepth, sourceProvider, sourceOffset, firstLineColumnOffset, alternative)
    {
    }
};

class ProgramCodeBlock : public GlobalCodeBlock {
public:
    ProgramCodeBlock(CopyParsedBlockTag, ProgramCodeBlock& other)
        : GlobalCodeBlock(CopyParsedBlock, other)
    {
    }

    ProgramCodeBlock(ProgramExecutable* ownerExecutable, UnlinkedProgramCodeBlock* unlinkedCodeBlock, JSGlobalObject* globalObject, PassRefPtr<SourceProvider> sourceProvider, unsigned firstLineColumnOffset, PassOwnPtr<CodeBlock> alternative)
        : GlobalCodeBlock(ownerExecutable, unlinkedCodeBlock, globalObject, 0, sourceProvider, 0, firstLineColumnOffset, alternative)
    {
    }

#if ENABLE(JIT)
protected:
    virtual JSObject* compileOptimized(ExecState*, JSScope*, unsigned bytecodeIndex);
    virtual void jettisonImpl();
    virtual bool jitCompileImpl(ExecState*);
    virtual CodeBlock* replacement();
    virtual DFG::CapabilityLevel canCompileWithDFGInternal();
#endif
};

class EvalCodeBlock : public GlobalCodeBlock {
public:
    EvalCodeBlock(CopyParsedBlockTag, EvalCodeBlock& other)
        : GlobalCodeBlock(CopyParsedBlock, other)
    {
    }
        
    EvalCodeBlock(EvalExecutable* ownerExecutable, UnlinkedEvalCodeBlock* unlinkedCodeBlock, JSGlobalObject* globalObject, PassRefPtr<SourceProvider> sourceProvider, int baseScopeDepth, PassOwnPtr<CodeBlock> alternative)
        : GlobalCodeBlock(ownerExecutable, unlinkedCodeBlock, globalObject, baseScopeDepth, sourceProvider, 0, 1, alternative)
    {
    }

    const Identifier& variable(unsigned index) { return unlinkedEvalCodeBlock()->variable(index); }
    unsigned numVariables() { return unlinkedEvalCodeBlock()->numVariables(); }
        
#if ENABLE(JIT)
protected:
    virtual JSObject* compileOptimized(ExecState*, JSScope*, unsigned bytecodeIndex);
    virtual void jettisonImpl();
    virtual bool jitCompileImpl(ExecState*);
    virtual CodeBlock* replacement();
    virtual DFG::CapabilityLevel canCompileWithDFGInternal();
#endif

private:
    UnlinkedEvalCodeBlock* unlinkedEvalCodeBlock() const { return jsCast<UnlinkedEvalCodeBlock*>(unlinkedCodeBlock()); }
};

class FunctionCodeBlock : public CodeBlock {
public:
    FunctionCodeBlock(CopyParsedBlockTag, FunctionCodeBlock& other)
        : CodeBlock(CopyParsedBlock, other)
    {
    }

    FunctionCodeBlock(FunctionExecutable* ownerExecutable, UnlinkedFunctionCodeBlock* unlinkedCodeBlock, JSGlobalObject* globalObject, PassRefPtr<SourceProvider> sourceProvider, unsigned sourceOffset, unsigned firstLineColumnOffset, PassOwnPtr<CodeBlock> alternative = nullptr)
        : CodeBlock(ownerExecutable, unlinkedCodeBlock, globalObject, 0, sourceProvider, sourceOffset, firstLineColumnOffset, alternative)
    {
    }
        
#if ENABLE(JIT)
protected:
    virtual JSObject* compileOptimized(ExecState*, JSScope*, unsigned bytecodeIndex);
    virtual void jettisonImpl();
    virtual bool jitCompileImpl(ExecState*);
    virtual CodeBlock* replacement();
    virtual DFG::CapabilityLevel canCompileWithDFGInternal();
#endif
};

inline CodeBlock* baselineCodeBlockForInlineCallFrame(InlineCallFrame* inlineCallFrame)
{
    RELEASE_ASSERT(inlineCallFrame);
    ExecutableBase* executable = inlineCallFrame->executable.get();
    RELEASE_ASSERT(executable->structure()->classInfo() == &FunctionExecutable::s_info);
    return static_cast<FunctionExecutable*>(executable)->baselineCodeBlockFor(inlineCallFrame->isCall ? CodeForCall : CodeForConstruct);
}
    
inline CodeBlock* baselineCodeBlockForOriginAndBaselineCodeBlock(const CodeOrigin& codeOrigin, CodeBlock* baselineCodeBlock)
{
    if (codeOrigin.inlineCallFrame)
        return baselineCodeBlockForInlineCallFrame(codeOrigin.inlineCallFrame);
    return baselineCodeBlock;
}

inline int CodeBlock::argumentIndexAfterCapture(size_t argument)
{
    if (argument >= static_cast<size_t>(symbolTable()->parameterCount()))
        return CallFrame::argumentOffset(argument);

    const SlowArgument* slowArguments = symbolTable()->slowArguments();
    if (!slowArguments || slowArguments[argument].status == SlowArgument::Normal)
        return CallFrame::argumentOffset(argument);

    ASSERT(slowArguments[argument].status == SlowArgument::Captured);
    return slowArguments[argument].index;
}

inline Register& ExecState::r(int index)
{
    CodeBlock* codeBlock = this->codeBlock();
    if (codeBlock->isConstantRegisterIndex(index))
        return *reinterpret_cast<Register*>(&codeBlock->constantRegister(index));
    return this[index];
}

inline Register& ExecState::uncheckedR(int index)
{
    RELEASE_ASSERT(index < FirstConstantRegisterIndex);
    return this[index];
}

#if ENABLE(DFG_JIT)
inline bool ExecState::isInlineCallFrame()
{
    if (LIKELY(!codeBlock() || codeBlock()->getJITType() != JITCode::DFGJIT))
        return false;
    return isInlineCallFrameSlow();
}
#endif

inline JSValue ExecState::argumentAfterCapture(size_t argument)
{
    if (argument >= argumentCount())
        return jsUndefined();

    if (!codeBlock())
        return this[argumentOffset(argument)].jsValue();

    return this[codeBlock()->argumentIndexAfterCapture(argument)].jsValue();
}

#if ENABLE(DFG_JIT)
inline void DFGCodeBlocks::mark(void* candidateCodeBlock)
{
    // We have to check for 0 and -1 because those are used by the HashMap as markers.
    uintptr_t value = reinterpret_cast<uintptr_t>(candidateCodeBlock);
        
    // This checks for both of those nasty cases in one go.
    // 0 + 1 = 1
    // -1 + 1 = 0
    if (value + 1 <= 1)
        return;
        
    HashSet<CodeBlock*>::iterator iter = m_set.find(static_cast<CodeBlock*>(candidateCodeBlock));
    if (iter == m_set.end())
        return;
        
    (*iter)->m_dfgData->mayBeExecuting = true;
}
#endif
    
} // namespace JSC

#endif // CodeBlock_h