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      1 /*
      2  * Copyright (C) 2008, 2009, 2010 Apple Inc. All rights reserved.
      3  * Copyright (C) 2008 Cameron Zwarich <cwzwarich (at) uwaterloo.ca>
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  *
      9  * 1.  Redistributions of source code must retain the above copyright
     10  *     notice, this list of conditions and the following disclaimer.
     11  * 2.  Redistributions in binary form must reproduce the above copyright
     12  *     notice, this list of conditions and the following disclaimer in the
     13  *     documentation and/or other materials provided with the distribution.
     14  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
     15  *     its contributors may be used to endorse or promote products derived
     16  *     from this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     19  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     20  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     21  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     22  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     23  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     24  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     25  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 #ifndef CodeBlock_h
     31 #define CodeBlock_h
     32 
     33 #include "EvalCodeCache.h"
     34 #include "Instruction.h"
     35 #include "JITCode.h"
     36 #include "JSGlobalObject.h"
     37 #include "JumpTable.h"
     38 #include "Nodes.h"
     39 #include "RegExp.h"
     40 #include "UString.h"
     41 #include <wtf/FastAllocBase.h>
     42 #include <wtf/PassOwnPtr.h>
     43 #include <wtf/RefPtr.h>
     44 #include <wtf/Vector.h>
     45 
     46 #if ENABLE(JIT)
     47 #include "StructureStubInfo.h"
     48 #endif
     49 
     50 // Register numbers used in bytecode operations have different meaning according to their ranges:
     51 //      0x80000000-0xFFFFFFFF  Negative indices from the CallFrame pointer are entries in the call frame, see RegisterFile.h.
     52 //      0x00000000-0x3FFFFFFF  Forwards indices from the CallFrame pointer are local vars and temporaries with the function's callframe.
     53 //      0x40000000-0x7FFFFFFF  Positive indices from 0x40000000 specify entries in the constant pool on the CodeBlock.
     54 static const int FirstConstantRegisterIndex = 0x40000000;
     55 
     56 namespace JSC {
     57 
     58     enum HasSeenShouldRepatch {
     59         hasSeenShouldRepatch
     60     };
     61 
     62     class ExecState;
     63 
     64     enum CodeType { GlobalCode, EvalCode, FunctionCode };
     65 
     66     inline int unmodifiedArgumentsRegister(int argumentsRegister) { return argumentsRegister - 1; }
     67 
     68     static ALWAYS_INLINE int missingThisObjectMarker() { return std::numeric_limits<int>::max(); }
     69 
     70     struct HandlerInfo {
     71         uint32_t start;
     72         uint32_t end;
     73         uint32_t target;
     74         uint32_t scopeDepth;
     75 #if ENABLE(JIT)
     76         CodeLocationLabel nativeCode;
     77 #endif
     78     };
     79 
     80     struct ExpressionRangeInfo {
     81         enum {
     82             MaxOffset = (1 << 7) - 1,
     83             MaxDivot = (1 << 25) - 1
     84         };
     85         uint32_t instructionOffset : 25;
     86         uint32_t divotPoint : 25;
     87         uint32_t startOffset : 7;
     88         uint32_t endOffset : 7;
     89     };
     90 
     91     struct LineInfo {
     92         uint32_t instructionOffset;
     93         int32_t lineNumber;
     94     };
     95 
     96 #if ENABLE(JIT)
     97     struct CallLinkInfo {
     98         CallLinkInfo()
     99             : hasSeenShouldRepatch(false)
    100         {
    101         }
    102 
    103         CodeLocationNearCall callReturnLocation;
    104         CodeLocationDataLabelPtr hotPathBegin;
    105         CodeLocationNearCall hotPathOther;
    106         WriteBarrier<JSFunction> callee;
    107         bool hasSeenShouldRepatch;
    108 
    109         void setUnlinked() { callee.clear(); }
    110         bool isLinked() { return callee; }
    111 
    112         bool seenOnce()
    113         {
    114             return hasSeenShouldRepatch;
    115         }
    116 
    117         void setSeen()
    118         {
    119             hasSeenShouldRepatch = true;
    120         }
    121     };
    122 
    123     struct MethodCallLinkInfo {
    124         MethodCallLinkInfo()
    125         {
    126         }
    127 
    128         bool seenOnce()
    129         {
    130             ASSERT(!cachedStructure);
    131             return cachedPrototypeStructure;
    132         }
    133 
    134         void setSeen()
    135         {
    136             ASSERT(!cachedStructure && !cachedPrototypeStructure);
    137             // We use the values of cachedStructure & cachedPrototypeStructure to indicate the
    138             // current state.
    139             //     - In the initial state, both are null.
    140             //     - Once this transition has been taken once, cachedStructure is
    141             //       null and cachedPrototypeStructure is set to a nun-null value.
    142             //     - Once the call is linked both structures are set to non-null values.
    143             cachedPrototypeStructure.setWithoutWriteBarrier((Structure*)1);
    144         }
    145 
    146         CodeLocationCall callReturnLocation;
    147         CodeLocationDataLabelPtr structureLabel;
    148         WriteBarrier<Structure> cachedStructure;
    149         WriteBarrier<Structure> cachedPrototypeStructure;
    150     };
    151 
    152     struct GlobalResolveInfo {
    153         GlobalResolveInfo(unsigned bytecodeOffset)
    154             : offset(0)
    155             , bytecodeOffset(bytecodeOffset)
    156         {
    157         }
    158 
    159         WriteBarrier<Structure> structure;
    160         unsigned offset;
    161         unsigned bytecodeOffset;
    162     };
    163 
    164     // This structure is used to map from a call return location
    165     // (given as an offset in bytes into the JIT code) back to
    166     // the bytecode index of the corresponding bytecode operation.
    167     // This is then used to look up the corresponding handler.
    168     struct CallReturnOffsetToBytecodeOffset {
    169         CallReturnOffsetToBytecodeOffset(unsigned callReturnOffset, unsigned bytecodeOffset)
    170             : callReturnOffset(callReturnOffset)
    171             , bytecodeOffset(bytecodeOffset)
    172         {
    173         }
    174 
    175         unsigned callReturnOffset;
    176         unsigned bytecodeOffset;
    177     };
    178 
    179     // valueAtPosition helpers for the binarySearch algorithm.
    180 
    181     inline void* getStructureStubInfoReturnLocation(StructureStubInfo* structureStubInfo)
    182     {
    183         return structureStubInfo->callReturnLocation.executableAddress();
    184     }
    185 
    186     inline void* getCallLinkInfoReturnLocation(CallLinkInfo* callLinkInfo)
    187     {
    188         return callLinkInfo->callReturnLocation.executableAddress();
    189     }
    190 
    191     inline void* getMethodCallLinkInfoReturnLocation(MethodCallLinkInfo* methodCallLinkInfo)
    192     {
    193         return methodCallLinkInfo->callReturnLocation.executableAddress();
    194     }
    195 
    196     inline unsigned getCallReturnOffset(CallReturnOffsetToBytecodeOffset* pc)
    197     {
    198         return pc->callReturnOffset;
    199     }
    200 #endif
    201 
    202     class CodeBlock {
    203         WTF_MAKE_FAST_ALLOCATED;
    204         friend class JIT;
    205     protected:
    206         CodeBlock(ScriptExecutable* ownerExecutable, CodeType, JSGlobalObject*, PassRefPtr<SourceProvider>, unsigned sourceOffset, SymbolTable* symbolTable, bool isConstructor);
    207 
    208         WriteBarrier<JSGlobalObject> m_globalObject;
    209         Heap* m_heap;
    210 
    211     public:
    212         virtual ~CodeBlock();
    213 
    214         void markAggregate(MarkStack&);
    215 
    216         static void dumpStatistics();
    217 
    218 #if !defined(NDEBUG) || ENABLE_OPCODE_SAMPLING
    219         void dump(ExecState*) const;
    220         void printStructures(const Instruction*) const;
    221         void printStructure(const char* name, const Instruction*, int operand) const;
    222 #endif
    223 
    224         bool isStrictMode() const { return m_isStrictMode; }
    225 
    226         inline bool isKnownNotImmediate(int index)
    227         {
    228             if (index == m_thisRegister && !m_isStrictMode)
    229                 return true;
    230 
    231             if (isConstantRegisterIndex(index))
    232                 return getConstant(index).isCell();
    233 
    234             return false;
    235         }
    236 
    237         ALWAYS_INLINE bool isTemporaryRegisterIndex(int index)
    238         {
    239             return index >= m_numVars;
    240         }
    241 
    242         HandlerInfo* handlerForBytecodeOffset(unsigned bytecodeOffset);
    243         int lineNumberForBytecodeOffset(unsigned bytecodeOffset);
    244         void expressionRangeForBytecodeOffset(unsigned bytecodeOffset, int& divot, int& startOffset, int& endOffset);
    245 
    246 #if ENABLE(JIT)
    247 
    248         StructureStubInfo& getStubInfo(ReturnAddressPtr returnAddress)
    249         {
    250             return *(binarySearch<StructureStubInfo, void*, getStructureStubInfoReturnLocation>(m_structureStubInfos.begin(), m_structureStubInfos.size(), returnAddress.value()));
    251         }
    252 
    253         CallLinkInfo& getCallLinkInfo(ReturnAddressPtr returnAddress)
    254         {
    255             return *(binarySearch<CallLinkInfo, void*, getCallLinkInfoReturnLocation>(m_callLinkInfos.begin(), m_callLinkInfos.size(), returnAddress.value()));
    256         }
    257 
    258         MethodCallLinkInfo& getMethodCallLinkInfo(ReturnAddressPtr returnAddress)
    259         {
    260             return *(binarySearch<MethodCallLinkInfo, void*, getMethodCallLinkInfoReturnLocation>(m_methodCallLinkInfos.begin(), m_methodCallLinkInfos.size(), returnAddress.value()));
    261         }
    262 
    263         unsigned bytecodeOffset(ReturnAddressPtr returnAddress)
    264         {
    265             if (!m_rareData)
    266                 return 1;
    267             Vector<CallReturnOffsetToBytecodeOffset>& callIndices = m_rareData->m_callReturnIndexVector;
    268             if (!callIndices.size())
    269                 return 1;
    270             return binarySearch<CallReturnOffsetToBytecodeOffset, unsigned, getCallReturnOffset>(callIndices.begin(), callIndices.size(), getJITCode().offsetOf(returnAddress.value()))->bytecodeOffset;
    271         }
    272 #endif
    273 #if ENABLE(INTERPRETER)
    274         unsigned bytecodeOffset(Instruction* returnAddress)
    275         {
    276             return static_cast<Instruction*>(returnAddress) - instructions().begin();
    277         }
    278 #endif
    279 
    280         void setIsNumericCompareFunction(bool isNumericCompareFunction) { m_isNumericCompareFunction = isNumericCompareFunction; }
    281         bool isNumericCompareFunction() { return m_isNumericCompareFunction; }
    282 
    283         Vector<Instruction>& instructions() { return m_instructions; }
    284         void discardBytecode() { m_instructions.clear(); }
    285 
    286 #ifndef NDEBUG
    287         unsigned instructionCount() { return m_instructionCount; }
    288         void setInstructionCount(unsigned instructionCount) { m_instructionCount = instructionCount; }
    289 #endif
    290 
    291 #if ENABLE(JIT)
    292         JITCode& getJITCode() { return m_isConstructor ? ownerExecutable()->generatedJITCodeForConstruct() : ownerExecutable()->generatedJITCodeForCall(); }
    293         ExecutablePool* executablePool() { return getJITCode().getExecutablePool(); }
    294 #endif
    295 
    296         ScriptExecutable* ownerExecutable() const { return m_ownerExecutable.get(); }
    297 
    298         void setGlobalData(JSGlobalData* globalData) { m_globalData = globalData; }
    299 
    300         void setThisRegister(int thisRegister) { m_thisRegister = thisRegister; }
    301         int thisRegister() const { return m_thisRegister; }
    302 
    303         void setNeedsFullScopeChain(bool needsFullScopeChain) { m_needsFullScopeChain = needsFullScopeChain; }
    304         bool needsFullScopeChain() const { return m_needsFullScopeChain; }
    305         void setUsesEval(bool usesEval) { m_usesEval = usesEval; }
    306         bool usesEval() const { return m_usesEval; }
    307 
    308         void setArgumentsRegister(int argumentsRegister)
    309         {
    310             ASSERT(argumentsRegister != -1);
    311             m_argumentsRegister = argumentsRegister;
    312             ASSERT(usesArguments());
    313         }
    314         int argumentsRegister()
    315         {
    316             ASSERT(usesArguments());
    317             return m_argumentsRegister;
    318         }
    319         void setActivationRegister(int activationRegister)
    320         {
    321             m_activationRegister = activationRegister;
    322         }
    323         int activationRegister()
    324         {
    325             ASSERT(needsFullScopeChain());
    326             return m_activationRegister;
    327         }
    328         bool usesArguments() const { return m_argumentsRegister != -1; }
    329 
    330         CodeType codeType() const { return m_codeType; }
    331 
    332         SourceProvider* source() const { return m_source.get(); }
    333         unsigned sourceOffset() const { return m_sourceOffset; }
    334 
    335         size_t numberOfJumpTargets() const { return m_jumpTargets.size(); }
    336         void addJumpTarget(unsigned jumpTarget) { m_jumpTargets.append(jumpTarget); }
    337         unsigned jumpTarget(int index) const { return m_jumpTargets[index]; }
    338         unsigned lastJumpTarget() const { return m_jumpTargets.last(); }
    339 
    340         void createActivation(CallFrame*);
    341 
    342 #if ENABLE(INTERPRETER)
    343         void addPropertyAccessInstruction(unsigned propertyAccessInstruction) { m_propertyAccessInstructions.append(propertyAccessInstruction); }
    344         void addGlobalResolveInstruction(unsigned globalResolveInstruction) { m_globalResolveInstructions.append(globalResolveInstruction); }
    345         bool hasGlobalResolveInstructionAtBytecodeOffset(unsigned bytecodeOffset);
    346 #endif
    347 #if ENABLE(JIT)
    348         size_t numberOfStructureStubInfos() const { return m_structureStubInfos.size(); }
    349         void addStructureStubInfo(const StructureStubInfo& stubInfo) { m_structureStubInfos.append(stubInfo); }
    350         StructureStubInfo& structureStubInfo(int index) { return m_structureStubInfos[index]; }
    351 
    352         void addGlobalResolveInfo(unsigned globalResolveInstruction) { m_globalResolveInfos.append(GlobalResolveInfo(globalResolveInstruction)); }
    353         GlobalResolveInfo& globalResolveInfo(int index) { return m_globalResolveInfos[index]; }
    354         bool hasGlobalResolveInfoAtBytecodeOffset(unsigned bytecodeOffset);
    355 
    356         size_t numberOfCallLinkInfos() const { return m_callLinkInfos.size(); }
    357         void addCallLinkInfo() { m_callLinkInfos.append(CallLinkInfo()); }
    358         CallLinkInfo& callLinkInfo(int index) { return m_callLinkInfos[index]; }
    359 
    360         void addMethodCallLinkInfos(unsigned n) { m_methodCallLinkInfos.grow(n); }
    361         MethodCallLinkInfo& methodCallLinkInfo(int index) { return m_methodCallLinkInfos[index]; }
    362 #endif
    363 
    364         // Exception handling support
    365 
    366         size_t numberOfExceptionHandlers() const { return m_rareData ? m_rareData->m_exceptionHandlers.size() : 0; }
    367         void addExceptionHandler(const HandlerInfo& hanler) { createRareDataIfNecessary(); return m_rareData->m_exceptionHandlers.append(hanler); }
    368         HandlerInfo& exceptionHandler(int index) { ASSERT(m_rareData); return m_rareData->m_exceptionHandlers[index]; }
    369 
    370         void addExpressionInfo(const ExpressionRangeInfo& expressionInfo)
    371         {
    372             createRareDataIfNecessary();
    373             m_rareData->m_expressionInfo.append(expressionInfo);
    374         }
    375 
    376         void addLineInfo(unsigned bytecodeOffset, int lineNo)
    377         {
    378             createRareDataIfNecessary();
    379             Vector<LineInfo>& lineInfo = m_rareData->m_lineInfo;
    380             if (!lineInfo.size() || lineInfo.last().lineNumber != lineNo) {
    381                 LineInfo info = { bytecodeOffset, lineNo };
    382                 lineInfo.append(info);
    383             }
    384         }
    385 
    386         bool hasExpressionInfo() { return m_rareData && m_rareData->m_expressionInfo.size(); }
    387         bool hasLineInfo() { return m_rareData && m_rareData->m_lineInfo.size(); }
    388         //  We only generate exception handling info if the user is debugging
    389         // (and may want line number info), or if the function contains exception handler.
    390         bool needsCallReturnIndices()
    391         {
    392             return m_rareData &&
    393                 (m_rareData->m_expressionInfo.size() || m_rareData->m_lineInfo.size() || m_rareData->m_exceptionHandlers.size());
    394         }
    395 
    396 #if ENABLE(JIT)
    397         Vector<CallReturnOffsetToBytecodeOffset>& callReturnIndexVector()
    398         {
    399             createRareDataIfNecessary();
    400             return m_rareData->m_callReturnIndexVector;
    401         }
    402 #endif
    403 
    404         // Constant Pool
    405 
    406         size_t numberOfIdentifiers() const { return m_identifiers.size(); }
    407         void addIdentifier(const Identifier& i) { return m_identifiers.append(i); }
    408         Identifier& identifier(int index) { return m_identifiers[index]; }
    409 
    410         size_t numberOfConstantRegisters() const { return m_constantRegisters.size(); }
    411         void addConstant(JSValue v)
    412         {
    413             m_constantRegisters.append(WriteBarrier<Unknown>());
    414             m_constantRegisters.last().set(m_globalObject->globalData(), m_ownerExecutable.get(), v);
    415         }
    416         WriteBarrier<Unknown>& constantRegister(int index) { return m_constantRegisters[index - FirstConstantRegisterIndex]; }
    417         ALWAYS_INLINE bool isConstantRegisterIndex(int index) const { return index >= FirstConstantRegisterIndex; }
    418         ALWAYS_INLINE JSValue getConstant(int index) const { return m_constantRegisters[index - FirstConstantRegisterIndex].get(); }
    419 
    420         unsigned addFunctionDecl(FunctionExecutable* n)
    421         {
    422             unsigned size = m_functionDecls.size();
    423             m_functionDecls.append(WriteBarrier<FunctionExecutable>());
    424             m_functionDecls.last().set(m_globalObject->globalData(), m_ownerExecutable.get(), n);
    425             return size;
    426         }
    427         FunctionExecutable* functionDecl(int index) { return m_functionDecls[index].get(); }
    428         int numberOfFunctionDecls() { return m_functionDecls.size(); }
    429         unsigned addFunctionExpr(FunctionExecutable* n)
    430         {
    431             unsigned size = m_functionExprs.size();
    432             m_functionExprs.append(WriteBarrier<FunctionExecutable>());
    433             m_functionExprs.last().set(m_globalObject->globalData(), m_ownerExecutable.get(), n);
    434             return size;
    435         }
    436         FunctionExecutable* functionExpr(int index) { return m_functionExprs[index].get(); }
    437 
    438         unsigned addRegExp(PassRefPtr<RegExp> r) { createRareDataIfNecessary(); unsigned size = m_rareData->m_regexps.size(); m_rareData->m_regexps.append(r); return size; }
    439         RegExp* regexp(int index) const { ASSERT(m_rareData); return m_rareData->m_regexps[index].get(); }
    440 
    441         JSGlobalObject* globalObject() { return m_globalObject.get(); }
    442 
    443         // Jump Tables
    444 
    445         size_t numberOfImmediateSwitchJumpTables() const { return m_rareData ? m_rareData->m_immediateSwitchJumpTables.size() : 0; }
    446         SimpleJumpTable& addImmediateSwitchJumpTable() { createRareDataIfNecessary(); m_rareData->m_immediateSwitchJumpTables.append(SimpleJumpTable()); return m_rareData->m_immediateSwitchJumpTables.last(); }
    447         SimpleJumpTable& immediateSwitchJumpTable(int tableIndex) { ASSERT(m_rareData); return m_rareData->m_immediateSwitchJumpTables[tableIndex]; }
    448 
    449         size_t numberOfCharacterSwitchJumpTables() const { return m_rareData ? m_rareData->m_characterSwitchJumpTables.size() : 0; }
    450         SimpleJumpTable& addCharacterSwitchJumpTable() { createRareDataIfNecessary(); m_rareData->m_characterSwitchJumpTables.append(SimpleJumpTable()); return m_rareData->m_characterSwitchJumpTables.last(); }
    451         SimpleJumpTable& characterSwitchJumpTable(int tableIndex) { ASSERT(m_rareData); return m_rareData->m_characterSwitchJumpTables[tableIndex]; }
    452 
    453         size_t numberOfStringSwitchJumpTables() const { return m_rareData ? m_rareData->m_stringSwitchJumpTables.size() : 0; }
    454         StringJumpTable& addStringSwitchJumpTable() { createRareDataIfNecessary(); m_rareData->m_stringSwitchJumpTables.append(StringJumpTable()); return m_rareData->m_stringSwitchJumpTables.last(); }
    455         StringJumpTable& stringSwitchJumpTable(int tableIndex) { ASSERT(m_rareData); return m_rareData->m_stringSwitchJumpTables[tableIndex]; }
    456 
    457 
    458         SymbolTable* symbolTable() { return m_symbolTable; }
    459         SharedSymbolTable* sharedSymbolTable() { ASSERT(m_codeType == FunctionCode); return static_cast<SharedSymbolTable*>(m_symbolTable); }
    460 
    461         EvalCodeCache& evalCodeCache() { createRareDataIfNecessary(); return m_rareData->m_evalCodeCache; }
    462 
    463         void shrinkToFit();
    464 
    465         // FIXME: Make these remaining members private.
    466 
    467         int m_numCalleeRegisters;
    468         int m_numVars;
    469         int m_numCapturedVars;
    470         int m_numParameters;
    471         bool m_isConstructor;
    472 
    473     private:
    474 #if !defined(NDEBUG) || ENABLE(OPCODE_SAMPLING)
    475         void dump(ExecState*, const Vector<Instruction>::const_iterator& begin, Vector<Instruction>::const_iterator&) const;
    476 
    477         CString registerName(ExecState*, int r) const;
    478         void printUnaryOp(ExecState*, int location, Vector<Instruction>::const_iterator&, const char* op) const;
    479         void printBinaryOp(ExecState*, int location, Vector<Instruction>::const_iterator&, const char* op) const;
    480         void printConditionalJump(ExecState*, const Vector<Instruction>::const_iterator&, Vector<Instruction>::const_iterator&, int location, const char* op) const;
    481         void printGetByIdOp(ExecState*, int location, Vector<Instruction>::const_iterator&, const char* op) const;
    482         void printPutByIdOp(ExecState*, int location, Vector<Instruction>::const_iterator&, const char* op) const;
    483 #endif
    484         void markStructures(MarkStack&, Instruction* vPC) const;
    485 
    486         void createRareDataIfNecessary()
    487         {
    488             if (!m_rareData)
    489                 m_rareData = adoptPtr(new RareData);
    490         }
    491 
    492         WriteBarrier<ScriptExecutable> m_ownerExecutable;
    493         JSGlobalData* m_globalData;
    494 
    495         Vector<Instruction> m_instructions;
    496 #ifndef NDEBUG
    497         unsigned m_instructionCount;
    498 #endif
    499 
    500         int m_thisRegister;
    501         int m_argumentsRegister;
    502         int m_activationRegister;
    503 
    504         bool m_needsFullScopeChain;
    505         bool m_usesEval;
    506         bool m_isNumericCompareFunction;
    507         bool m_isStrictMode;
    508 
    509         CodeType m_codeType;
    510 
    511         RefPtr<SourceProvider> m_source;
    512         unsigned m_sourceOffset;
    513 
    514 #if ENABLE(INTERPRETER)
    515         Vector<unsigned> m_propertyAccessInstructions;
    516         Vector<unsigned> m_globalResolveInstructions;
    517 #endif
    518 #if ENABLE(JIT)
    519         Vector<StructureStubInfo> m_structureStubInfos;
    520         Vector<GlobalResolveInfo> m_globalResolveInfos;
    521         Vector<CallLinkInfo> m_callLinkInfos;
    522         Vector<MethodCallLinkInfo> m_methodCallLinkInfos;
    523 #endif
    524 
    525         Vector<unsigned> m_jumpTargets;
    526 
    527         // Constant Pool
    528         Vector<Identifier> m_identifiers;
    529         COMPILE_ASSERT(sizeof(Register) == sizeof(WriteBarrier<Unknown>), Register_must_be_same_size_as_WriteBarrier_Unknown);
    530         Vector<WriteBarrier<Unknown> > m_constantRegisters;
    531         Vector<WriteBarrier<FunctionExecutable> > m_functionDecls;
    532         Vector<WriteBarrier<FunctionExecutable> > m_functionExprs;
    533 
    534         SymbolTable* m_symbolTable;
    535 
    536         struct RareData {
    537            WTF_MAKE_FAST_ALLOCATED;
    538         public:
    539             Vector<HandlerInfo> m_exceptionHandlers;
    540 
    541             // Rare Constants
    542             Vector<RefPtr<RegExp> > m_regexps;
    543 
    544             // Jump Tables
    545             Vector<SimpleJumpTable> m_immediateSwitchJumpTables;
    546             Vector<SimpleJumpTable> m_characterSwitchJumpTables;
    547             Vector<StringJumpTable> m_stringSwitchJumpTables;
    548 
    549             EvalCodeCache m_evalCodeCache;
    550 
    551             // Expression info - present if debugging.
    552             Vector<ExpressionRangeInfo> m_expressionInfo;
    553             // Line info - present if profiling or debugging.
    554             Vector<LineInfo> m_lineInfo;
    555 #if ENABLE(JIT)
    556             Vector<CallReturnOffsetToBytecodeOffset> m_callReturnIndexVector;
    557 #endif
    558         };
    559 #if COMPILER(MSVC)
    560         friend void WTF::deleteOwnedPtr<RareData>(RareData*);
    561 #endif
    562         OwnPtr<RareData> m_rareData;
    563     };
    564 
    565     // Program code is not marked by any function, so we make the global object
    566     // responsible for marking it.
    567 
    568     class GlobalCodeBlock : public CodeBlock {
    569     public:
    570         GlobalCodeBlock(ScriptExecutable* ownerExecutable, CodeType codeType, JSGlobalObject* globalObject, PassRefPtr<SourceProvider> sourceProvider, unsigned sourceOffset)
    571             : CodeBlock(ownerExecutable, codeType, globalObject, sourceProvider, sourceOffset, &m_unsharedSymbolTable, false)
    572         {
    573         }
    574 
    575     private:
    576         SymbolTable m_unsharedSymbolTable;
    577     };
    578 
    579     class ProgramCodeBlock : public GlobalCodeBlock {
    580     public:
    581         ProgramCodeBlock(ProgramExecutable* ownerExecutable, CodeType codeType, JSGlobalObject* globalObject, PassRefPtr<SourceProvider> sourceProvider)
    582             : GlobalCodeBlock(ownerExecutable, codeType, globalObject, sourceProvider, 0)
    583         {
    584         }
    585     };
    586 
    587     class EvalCodeBlock : public GlobalCodeBlock {
    588     public:
    589         EvalCodeBlock(EvalExecutable* ownerExecutable, JSGlobalObject* globalObject, PassRefPtr<SourceProvider> sourceProvider, int baseScopeDepth)
    590             : GlobalCodeBlock(ownerExecutable, EvalCode, globalObject, sourceProvider, 0)
    591             , m_baseScopeDepth(baseScopeDepth)
    592         {
    593         }
    594 
    595         int baseScopeDepth() const { return m_baseScopeDepth; }
    596 
    597         const Identifier& variable(unsigned index) { return m_variables[index]; }
    598         unsigned numVariables() { return m_variables.size(); }
    599         void adoptVariables(Vector<Identifier>& variables)
    600         {
    601             ASSERT(m_variables.isEmpty());
    602             m_variables.swap(variables);
    603         }
    604 
    605     private:
    606         int m_baseScopeDepth;
    607         Vector<Identifier> m_variables;
    608     };
    609 
    610     class FunctionCodeBlock : public CodeBlock {
    611     public:
    612         // Rather than using the usual RefCounted::create idiom for SharedSymbolTable we just use new
    613         // as we need to initialise the CodeBlock before we could initialise any RefPtr to hold the shared
    614         // symbol table, so we just pass as a raw pointer with a ref count of 1.  We then manually deref
    615         // in the destructor.
    616         FunctionCodeBlock(FunctionExecutable* ownerExecutable, CodeType codeType, JSGlobalObject* globalObject, PassRefPtr<SourceProvider> sourceProvider, unsigned sourceOffset, bool isConstructor)
    617             : CodeBlock(ownerExecutable, codeType, globalObject, sourceProvider, sourceOffset, SharedSymbolTable::create().leakRef(), isConstructor)
    618         {
    619         }
    620         ~FunctionCodeBlock()
    621         {
    622             sharedSymbolTable()->deref();
    623         }
    624     };
    625 
    626     inline Register& ExecState::r(int index)
    627     {
    628         CodeBlock* codeBlock = this->codeBlock();
    629         if (codeBlock->isConstantRegisterIndex(index))
    630             return *reinterpret_cast<Register*>(&codeBlock->constantRegister(index));
    631         return this[index];
    632     }
    633 
    634     inline Register& ExecState::uncheckedR(int index)
    635     {
    636         ASSERT(index < FirstConstantRegisterIndex);
    637         return this[index];
    638     }
    639 
    640 } // namespace JSC
    641 
    642 #endif // CodeBlock_h
    643