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      1 /*
      2  * Copyright (C) 2008, 2009 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 BytecodeGenerator_h
     31 #define BytecodeGenerator_h
     32 
     33 #include "CodeBlock.h"
     34 #include "HashTraits.h"
     35 #include "Instruction.h"
     36 #include "Label.h"
     37 #include "LabelScope.h"
     38 #include "Interpreter.h"
     39 #include "RegisterID.h"
     40 #include "SymbolTable.h"
     41 #include "Debugger.h"
     42 #include "Nodes.h"
     43 #include <wtf/FastAllocBase.h>
     44 #include <wtf/PassRefPtr.h>
     45 #include <wtf/SegmentedVector.h>
     46 #include <wtf/Vector.h>
     47 
     48 namespace JSC {
     49 
     50     class Identifier;
     51     class ScopeChain;
     52     class ScopeNode;
     53 
     54     struct FinallyContext {
     55         Label* finallyAddr;
     56         RegisterID* retAddrDst;
     57     };
     58 
     59     struct ControlFlowContext {
     60         bool isFinallyBlock;
     61         FinallyContext finallyContext;
     62     };
     63 
     64     struct ForInContext {
     65         RefPtr<RegisterID> expectedSubscriptRegister;
     66         RefPtr<RegisterID> iterRegister;
     67         RefPtr<RegisterID> indexRegister;
     68         RefPtr<RegisterID> propertyRegister;
     69     };
     70 
     71     class BytecodeGenerator : public FastAllocBase {
     72     public:
     73         typedef DeclarationStacks::VarStack VarStack;
     74         typedef DeclarationStacks::FunctionStack FunctionStack;
     75 
     76         static void setDumpsGeneratedCode(bool dumpsGeneratedCode);
     77         static bool dumpsGeneratedCode();
     78 
     79         BytecodeGenerator(ProgramNode*, const Debugger*, const ScopeChain&, SymbolTable*, ProgramCodeBlock*);
     80         BytecodeGenerator(FunctionBodyNode*, const Debugger*, const ScopeChain&, SymbolTable*, CodeBlock*);
     81         BytecodeGenerator(EvalNode*, const Debugger*, const ScopeChain&, SymbolTable*, EvalCodeBlock*);
     82 
     83         JSGlobalData* globalData() const { return m_globalData; }
     84         const CommonIdentifiers& propertyNames() const { return *m_globalData->propertyNames; }
     85 
     86         void generate();
     87 
     88         // Returns the register corresponding to a local variable, or 0 if no
     89         // such register exists. Registers returned by registerFor do not
     90         // require explicit reference counting.
     91         RegisterID* registerFor(const Identifier&);
     92 
     93         bool willResolveToArguments(const Identifier&);
     94         RegisterID* uncheckedRegisterForArguments();
     95 
     96         // Behaves as registerFor does, but ignores dynamic scope as
     97         // dynamic scope should not interfere with const initialisation
     98         RegisterID* constRegisterFor(const Identifier&);
     99 
    100         // Searches the scope chain in an attempt to  statically locate the requested
    101         // property.  Returns false if for any reason the property cannot be safely
    102         // optimised at all.  Otherwise it will return the index and depth of the
    103         // VariableObject that defines the property.  If the property cannot be found
    104         // statically, depth will contain the depth of the scope chain where dynamic
    105         // lookup must begin.
    106         //
    107         // NB: depth does _not_ include the local scope.  eg. a depth of 0 refers
    108         // to the scope containing this codeblock.
    109         bool findScopedProperty(const Identifier&, int& index, size_t& depth, bool forWriting, JSObject*& globalObject);
    110 
    111         // Returns the register storing "this"
    112         RegisterID* thisRegister() { return &m_thisRegister; }
    113 
    114         bool isLocal(const Identifier&);
    115         bool isLocalConstant(const Identifier&);
    116 
    117         // Returns the next available temporary register. Registers returned by
    118         // newTemporary require a modified form of reference counting: any
    119         // register with a refcount of 0 is considered "available", meaning that
    120         // the next instruction may overwrite it.
    121         RegisterID* newTemporary();
    122 
    123         RegisterID* highestUsedRegister();
    124 
    125         // The same as newTemporary(), but this function returns "suggestion" if
    126         // "suggestion" is a temporary. This function is helpful in situations
    127         // where you've put "suggestion" in a RefPtr, but you'd like to allow
    128         // the next instruction to overwrite it anyway.
    129         RegisterID* newTemporaryOr(RegisterID* suggestion) { return suggestion->isTemporary() ? suggestion : newTemporary(); }
    130 
    131         // Functions for handling of dst register
    132 
    133         RegisterID* ignoredResult() { return &m_ignoredResultRegister; }
    134 
    135         // Returns a place to write intermediate values of an operation
    136         // which reuses dst if it is safe to do so.
    137         RegisterID* tempDestination(RegisterID* dst)
    138         {
    139             return (dst && dst != ignoredResult() && dst->isTemporary()) ? dst : newTemporary();
    140         }
    141 
    142         // Returns the place to write the final output of an operation.
    143         RegisterID* finalDestination(RegisterID* originalDst, RegisterID* tempDst = 0)
    144         {
    145             if (originalDst && originalDst != ignoredResult())
    146                 return originalDst;
    147             ASSERT(tempDst != ignoredResult());
    148             if (tempDst && tempDst->isTemporary())
    149                 return tempDst;
    150             return newTemporary();
    151         }
    152 
    153         RegisterID* destinationForAssignResult(RegisterID* dst)
    154         {
    155             if (dst && dst != ignoredResult() && m_codeBlock->needsFullScopeChain())
    156                 return dst->isTemporary() ? dst : newTemporary();
    157             return 0;
    158         }
    159 
    160         // Moves src to dst if dst is not null and is different from src, otherwise just returns src.
    161         RegisterID* moveToDestinationIfNeeded(RegisterID* dst, RegisterID* src)
    162         {
    163             return dst == ignoredResult() ? 0 : (dst && dst != src) ? emitMove(dst, src) : src;
    164         }
    165 
    166         PassRefPtr<LabelScope> newLabelScope(LabelScope::Type, const Identifier* = 0);
    167         PassRefPtr<Label> newLabel();
    168 
    169         // The emitNode functions are just syntactic sugar for calling
    170         // Node::emitCode. These functions accept a 0 for the register,
    171         // meaning that the node should allocate a register, or ignoredResult(),
    172         // meaning that the node need not put the result in a register.
    173         // Other emit functions do not accept 0 or ignoredResult().
    174         RegisterID* emitNode(RegisterID* dst, Node* n)
    175         {
    176             // Node::emitCode assumes that dst, if provided, is either a local or a referenced temporary.
    177             ASSERT(!dst || dst == ignoredResult() || !dst->isTemporary() || dst->refCount());
    178             if (!m_codeBlock->numberOfLineInfos() || m_codeBlock->lastLineInfo().lineNumber != n->lineNo()) {
    179                 LineInfo info = { instructions().size(), n->lineNo() };
    180                 m_codeBlock->addLineInfo(info);
    181             }
    182             if (m_emitNodeDepth >= s_maxEmitNodeDepth)
    183                 return emitThrowExpressionTooDeepException();
    184             ++m_emitNodeDepth;
    185             RegisterID* r = n->emitBytecode(*this, dst);
    186             --m_emitNodeDepth;
    187             return r;
    188         }
    189 
    190         RegisterID* emitNode(Node* n)
    191         {
    192             return emitNode(0, n);
    193         }
    194 
    195         void emitNodeInConditionContext(ExpressionNode* n, Label* trueTarget, Label* falseTarget, bool fallThroughMeansTrue)
    196         {
    197             if (!m_codeBlock->numberOfLineInfos() || m_codeBlock->lastLineInfo().lineNumber != n->lineNo()) {
    198                 LineInfo info = { instructions().size(), n->lineNo() };
    199                 m_codeBlock->addLineInfo(info);
    200             }
    201             if (m_emitNodeDepth >= s_maxEmitNodeDepth)
    202                 emitThrowExpressionTooDeepException();
    203             ++m_emitNodeDepth;
    204             n->emitBytecodeInConditionContext(*this, trueTarget, falseTarget, fallThroughMeansTrue);
    205             --m_emitNodeDepth;
    206         }
    207 
    208         void emitExpressionInfo(unsigned divot, unsigned startOffset, unsigned endOffset)
    209         {
    210             divot -= m_codeBlock->sourceOffset();
    211             if (divot > ExpressionRangeInfo::MaxDivot) {
    212                 // Overflow has occurred, we can only give line number info for errors for this region
    213                 divot = 0;
    214                 startOffset = 0;
    215                 endOffset = 0;
    216             } else if (startOffset > ExpressionRangeInfo::MaxOffset) {
    217                 // If the start offset is out of bounds we clear both offsets
    218                 // so we only get the divot marker.  Error message will have to be reduced
    219                 // to line and column number.
    220                 startOffset = 0;
    221                 endOffset = 0;
    222             } else if (endOffset > ExpressionRangeInfo::MaxOffset) {
    223                 // The end offset is only used for additional context, and is much more likely
    224                 // to overflow (eg. function call arguments) so we are willing to drop it without
    225                 // dropping the rest of the range.
    226                 endOffset = 0;
    227             }
    228 
    229             ExpressionRangeInfo info;
    230             info.instructionOffset = instructions().size();
    231             info.divotPoint = divot;
    232             info.startOffset = startOffset;
    233             info.endOffset = endOffset;
    234             m_codeBlock->addExpressionInfo(info);
    235         }
    236 
    237         void emitGetByIdExceptionInfo(OpcodeID opcodeID)
    238         {
    239             // Only op_construct and op_instanceof need exception info for
    240             // a preceding op_get_by_id.
    241             ASSERT(opcodeID == op_construct || opcodeID == op_instanceof);
    242             GetByIdExceptionInfo info;
    243             info.bytecodeOffset = instructions().size();
    244             info.isOpConstruct = (opcodeID == op_construct);
    245             m_codeBlock->addGetByIdExceptionInfo(info);
    246         }
    247 
    248         ALWAYS_INLINE bool leftHandSideNeedsCopy(bool rightHasAssignments, bool rightIsPure)
    249         {
    250             return (m_codeType != FunctionCode || m_codeBlock->needsFullScopeChain() || rightHasAssignments) && !rightIsPure;
    251         }
    252 
    253         ALWAYS_INLINE PassRefPtr<RegisterID> emitNodeForLeftHandSide(ExpressionNode* n, bool rightHasAssignments, bool rightIsPure)
    254         {
    255             if (leftHandSideNeedsCopy(rightHasAssignments, rightIsPure)) {
    256                 PassRefPtr<RegisterID> dst = newTemporary();
    257                 emitNode(dst.get(), n);
    258                 return dst;
    259             }
    260 
    261             return PassRefPtr<RegisterID>(emitNode(n));
    262         }
    263 
    264         RegisterID* emitLoad(RegisterID* dst, bool);
    265         RegisterID* emitLoad(RegisterID* dst, double);
    266         RegisterID* emitLoad(RegisterID* dst, const Identifier&);
    267         RegisterID* emitLoad(RegisterID* dst, JSValue);
    268 
    269         RegisterID* emitUnaryOp(OpcodeID, RegisterID* dst, RegisterID* src);
    270         RegisterID* emitBinaryOp(OpcodeID, RegisterID* dst, RegisterID* src1, RegisterID* src2, OperandTypes);
    271         RegisterID* emitEqualityOp(OpcodeID, RegisterID* dst, RegisterID* src1, RegisterID* src2);
    272         RegisterID* emitUnaryNoDstOp(OpcodeID, RegisterID* src);
    273 
    274         RegisterID* emitNewObject(RegisterID* dst);
    275         RegisterID* emitNewArray(RegisterID* dst, ElementNode*); // stops at first elision
    276 
    277         RegisterID* emitNewFunction(RegisterID* dst, FunctionBodyNode* body);
    278         RegisterID* emitNewFunctionExpression(RegisterID* dst, FuncExprNode* func);
    279         RegisterID* emitNewRegExp(RegisterID* dst, RegExp* regExp);
    280 
    281         RegisterID* emitMove(RegisterID* dst, RegisterID* src);
    282 
    283         RegisterID* emitToJSNumber(RegisterID* dst, RegisterID* src) { return emitUnaryOp(op_to_jsnumber, dst, src); }
    284         RegisterID* emitPreInc(RegisterID* srcDst);
    285         RegisterID* emitPreDec(RegisterID* srcDst);
    286         RegisterID* emitPostInc(RegisterID* dst, RegisterID* srcDst);
    287         RegisterID* emitPostDec(RegisterID* dst, RegisterID* srcDst);
    288 
    289         RegisterID* emitInstanceOf(RegisterID* dst, RegisterID* value, RegisterID* base, RegisterID* basePrototype);
    290         RegisterID* emitTypeOf(RegisterID* dst, RegisterID* src) { return emitUnaryOp(op_typeof, dst, src); }
    291         RegisterID* emitIn(RegisterID* dst, RegisterID* property, RegisterID* base) { return emitBinaryOp(op_in, dst, property, base, OperandTypes()); }
    292 
    293         RegisterID* emitResolve(RegisterID* dst, const Identifier& property);
    294         RegisterID* emitGetScopedVar(RegisterID* dst, size_t skip, int index, JSValue globalObject);
    295         RegisterID* emitPutScopedVar(size_t skip, int index, RegisterID* value, JSValue globalObject);
    296 
    297         RegisterID* emitResolveBase(RegisterID* dst, const Identifier& property);
    298         RegisterID* emitResolveWithBase(RegisterID* baseDst, RegisterID* propDst, const Identifier& property);
    299 
    300         void emitMethodCheck();
    301 
    302         RegisterID* emitGetById(RegisterID* dst, RegisterID* base, const Identifier& property);
    303         RegisterID* emitPutById(RegisterID* base, const Identifier& property, RegisterID* value);
    304         RegisterID* emitDeleteById(RegisterID* dst, RegisterID* base, const Identifier&);
    305         RegisterID* emitGetByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
    306         RegisterID* emitPutByVal(RegisterID* base, RegisterID* property, RegisterID* value);
    307         RegisterID* emitDeleteByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
    308         RegisterID* emitPutByIndex(RegisterID* base, unsigned index, RegisterID* value);
    309         RegisterID* emitPutGetter(RegisterID* base, const Identifier& property, RegisterID* value);
    310         RegisterID* emitPutSetter(RegisterID* base, const Identifier& property, RegisterID* value);
    311 
    312         RegisterID* emitCall(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
    313         RegisterID* emitCallEval(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
    314         RegisterID* emitCallVarargs(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, RegisterID* argCount, unsigned divot, unsigned startOffset, unsigned endOffset);
    315         RegisterID* emitLoadVarargs(RegisterID* argCountDst, RegisterID* args);
    316 
    317         RegisterID* emitReturn(RegisterID* src);
    318         RegisterID* emitEnd(RegisterID* src) { return emitUnaryNoDstOp(op_end, src); }
    319 
    320         RegisterID* emitConstruct(RegisterID* dst, RegisterID* func, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
    321         RegisterID* emitStrcat(RegisterID* dst, RegisterID* src, int count);
    322         void emitToPrimitive(RegisterID* dst, RegisterID* src);
    323 
    324         PassRefPtr<Label> emitLabel(Label*);
    325         PassRefPtr<Label> emitJump(Label* target);
    326         PassRefPtr<Label> emitJumpIfTrue(RegisterID* cond, Label* target);
    327         PassRefPtr<Label> emitJumpIfFalse(RegisterID* cond, Label* target);
    328         PassRefPtr<Label> emitJumpIfNotFunctionCall(RegisterID* cond, Label* target);
    329         PassRefPtr<Label> emitJumpIfNotFunctionApply(RegisterID* cond, Label* target);
    330         PassRefPtr<Label> emitJumpScopes(Label* target, int targetScopeDepth);
    331 
    332         PassRefPtr<Label> emitJumpSubroutine(RegisterID* retAddrDst, Label*);
    333         void emitSubroutineReturn(RegisterID* retAddrSrc);
    334 
    335         RegisterID* emitGetPropertyNames(RegisterID* dst, RegisterID* base, RegisterID* i, RegisterID* size, Label* breakTarget);
    336         RegisterID* emitNextPropertyName(RegisterID* dst, RegisterID* base, RegisterID* i, RegisterID* size, RegisterID* iter, Label* target);
    337 
    338         RegisterID* emitCatch(RegisterID*, Label* start, Label* end);
    339         void emitThrow(RegisterID* exc) { emitUnaryNoDstOp(op_throw, exc); }
    340         RegisterID* emitNewError(RegisterID* dst, ErrorType type, JSValue message);
    341         void emitPushNewScope(RegisterID* dst, const Identifier& property, RegisterID* value);
    342 
    343         RegisterID* emitPushScope(RegisterID* scope);
    344         void emitPopScope();
    345 
    346         void emitDebugHook(DebugHookID, int firstLine, int lastLine);
    347 
    348         int scopeDepth() { return m_dynamicScopeDepth + m_finallyDepth; }
    349         bool hasFinaliser() { return m_finallyDepth != 0; }
    350 
    351         void pushFinallyContext(Label* target, RegisterID* returnAddrDst);
    352         void popFinallyContext();
    353 
    354         void pushOptimisedForIn(RegisterID* expectedBase, RegisterID* iter, RegisterID* index, RegisterID* propertyRegister)
    355         {
    356             ForInContext context = { expectedBase, iter, index, propertyRegister };
    357             m_forInContextStack.append(context);
    358         }
    359 
    360         void popOptimisedForIn()
    361         {
    362             m_forInContextStack.removeLast();
    363         }
    364 
    365         LabelScope* breakTarget(const Identifier&);
    366         LabelScope* continueTarget(const Identifier&);
    367 
    368         void beginSwitch(RegisterID*, SwitchInfo::SwitchType);
    369         void endSwitch(uint32_t clauseCount, RefPtr<Label>*, ExpressionNode**, Label* defaultLabel, int32_t min, int32_t range);
    370 
    371         CodeType codeType() const { return m_codeType; }
    372 
    373         void setRegeneratingForExceptionInfo(CodeBlock* originalCodeBlock)
    374         {
    375             m_regeneratingForExceptionInfo = true;
    376             m_codeBlockBeingRegeneratedFrom = originalCodeBlock;
    377         }
    378 
    379     private:
    380         void emitOpcode(OpcodeID);
    381         void retrieveLastBinaryOp(int& dstIndex, int& src1Index, int& src2Index);
    382         void retrieveLastUnaryOp(int& dstIndex, int& srcIndex);
    383         void rewindBinaryOp();
    384         void rewindUnaryOp();
    385 
    386         PassRefPtr<Label> emitComplexJumpScopes(Label* target, ControlFlowContext* topScope, ControlFlowContext* bottomScope);
    387 
    388         typedef HashMap<EncodedJSValue, unsigned, EncodedJSValueHash, EncodedJSValueHashTraits> JSValueMap;
    389 
    390         struct IdentifierMapIndexHashTraits {
    391             typedef int TraitType;
    392             typedef IdentifierMapIndexHashTraits StorageTraits;
    393             static int emptyValue() { return std::numeric_limits<int>::max(); }
    394             static const bool emptyValueIsZero = false;
    395             static const bool needsDestruction = false;
    396             static const bool needsRef = false;
    397         };
    398 
    399         typedef HashMap<RefPtr<UString::Rep>, int, IdentifierRepHash, HashTraits<RefPtr<UString::Rep> >, IdentifierMapIndexHashTraits> IdentifierMap;
    400         typedef HashMap<double, JSValue> NumberMap;
    401         typedef HashMap<UString::Rep*, JSString*, IdentifierRepHash> IdentifierStringMap;
    402 
    403         RegisterID* emitCall(OpcodeID, RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
    404 
    405         RegisterID* newRegister();
    406 
    407         // Returns the RegisterID corresponding to ident.
    408         RegisterID* addVar(const Identifier& ident, bool isConstant)
    409         {
    410             RegisterID* local;
    411             addVar(ident, isConstant, local);
    412             return local;
    413         }
    414         // Returns true if a new RegisterID was added, false if a pre-existing RegisterID was re-used.
    415         bool addVar(const Identifier&, bool isConstant, RegisterID*&);
    416 
    417         // Returns the RegisterID corresponding to ident.
    418         RegisterID* addGlobalVar(const Identifier& ident, bool isConstant)
    419         {
    420             RegisterID* local;
    421             addGlobalVar(ident, isConstant, local);
    422             return local;
    423         }
    424         // Returns true if a new RegisterID was added, false if a pre-existing RegisterID was re-used.
    425         bool addGlobalVar(const Identifier&, bool isConstant, RegisterID*&);
    426 
    427         RegisterID* addParameter(const Identifier&);
    428 
    429         void preserveLastVar();
    430 
    431         RegisterID& registerFor(int index)
    432         {
    433             if (index >= 0)
    434                 return m_calleeRegisters[index];
    435 
    436             if (index == RegisterFile::OptionalCalleeArguments)
    437                 return m_argumentsRegister;
    438 
    439             if (m_parameters.size()) {
    440                 ASSERT(!m_globals.size());
    441                 return m_parameters[index + m_parameters.size() + RegisterFile::CallFrameHeaderSize];
    442             }
    443 
    444             return m_globals[-index - 1];
    445         }
    446 
    447         unsigned addConstant(const Identifier&);
    448         RegisterID* addConstantValue(JSValue);
    449         unsigned addRegExp(RegExp*);
    450 
    451         PassRefPtr<FunctionExecutable> makeFunction(ExecState* exec, FunctionBodyNode* body)
    452         {
    453             return FunctionExecutable::create(exec, body->ident(), body->source(), body->usesArguments(), body->parameters(), body->lineNo(), body->lastLine());
    454         }
    455 
    456         PassRefPtr<FunctionExecutable> makeFunction(JSGlobalData* globalData, FunctionBodyNode* body)
    457         {
    458             return FunctionExecutable::create(globalData, body->ident(), body->source(), body->usesArguments(), body->parameters(), body->lineNo(), body->lastLine());
    459         }
    460 
    461         Vector<Instruction>& instructions() { return m_codeBlock->instructions(); }
    462         SymbolTable& symbolTable() { return *m_symbolTable; }
    463 
    464         bool shouldOptimizeLocals() { return (m_codeType != EvalCode) && !m_dynamicScopeDepth; }
    465         bool canOptimizeNonLocals() { return (m_codeType == FunctionCode) && !m_dynamicScopeDepth && !m_codeBlock->usesEval(); }
    466 
    467         RegisterID* emitThrowExpressionTooDeepException();
    468 
    469         void createArgumentsIfNecessary();
    470 
    471         bool m_shouldEmitDebugHooks;
    472         bool m_shouldEmitProfileHooks;
    473 
    474         const ScopeChain* m_scopeChain;
    475         SymbolTable* m_symbolTable;
    476 
    477         ScopeNode* m_scopeNode;
    478         CodeBlock* m_codeBlock;
    479 
    480         // Some of these objects keep pointers to one another. They are arranged
    481         // to ensure a sane destruction order that avoids references to freed memory.
    482         HashSet<RefPtr<UString::Rep>, IdentifierRepHash> m_functions;
    483         RegisterID m_ignoredResultRegister;
    484         RegisterID m_thisRegister;
    485         RegisterID m_argumentsRegister;
    486         int m_activationRegisterIndex;
    487         SegmentedVector<RegisterID, 32> m_constantPoolRegisters;
    488         SegmentedVector<RegisterID, 32> m_calleeRegisters;
    489         SegmentedVector<RegisterID, 32> m_parameters;
    490         SegmentedVector<RegisterID, 32> m_globals;
    491         SegmentedVector<Label, 32> m_labels;
    492         SegmentedVector<LabelScope, 8> m_labelScopes;
    493         RefPtr<RegisterID> m_lastVar;
    494         int m_finallyDepth;
    495         int m_dynamicScopeDepth;
    496         int m_baseScopeDepth;
    497         CodeType m_codeType;
    498 
    499         Vector<ControlFlowContext> m_scopeContextStack;
    500         Vector<SwitchInfo> m_switchContextStack;
    501         Vector<ForInContext> m_forInContextStack;
    502 
    503         int m_nextGlobalIndex;
    504         int m_nextParameterIndex;
    505         int m_firstConstantIndex;
    506         int m_nextConstantOffset;
    507         unsigned m_globalConstantIndex;
    508 
    509         int m_globalVarStorageOffset;
    510 
    511         // Constant pool
    512         IdentifierMap m_identifierMap;
    513         JSValueMap m_jsValueMap;
    514         NumberMap m_numberMap;
    515         IdentifierStringMap m_stringMap;
    516 
    517         JSGlobalData* m_globalData;
    518 
    519         OpcodeID m_lastOpcodeID;
    520 
    521         unsigned m_emitNodeDepth;
    522 
    523         bool m_regeneratingForExceptionInfo;
    524         CodeBlock* m_codeBlockBeingRegeneratedFrom;
    525 
    526         static const unsigned s_maxEmitNodeDepth = 5000;
    527     };
    528 
    529 }
    530 
    531 #endif // BytecodeGenerator_h
    532