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1 /*
2  * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
3  * Copyright (C) 2008 Cameron Zwarich <cwzwarich@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     class BytecodeGenerator : public WTF::FastAllocBase {
65     public:
66         typedef DeclarationStacks::VarStack VarStack;
67         typedef DeclarationStacks::FunctionStack FunctionStack;
68 
69         static void setDumpsGeneratedCode(bool dumpsGeneratedCode);
70         static bool dumpsGeneratedCode();
71 
72         BytecodeGenerator(ProgramNode*, const Debugger*, const ScopeChain&, SymbolTable*, ProgramCodeBlock*);
73         BytecodeGenerator(FunctionBodyNode*, const Debugger*, const ScopeChain&, SymbolTable*, CodeBlock*);
74         BytecodeGenerator(EvalNode*, const Debugger*, const ScopeChain&, SymbolTable*, EvalCodeBlock*);
75 
globalData()76         JSGlobalData* globalData() const { return m_globalData; }
propertyNames()77         const CommonIdentifiers& propertyNames() const { return *m_globalData->propertyNames; }
78 
79         void generate();
80 
81         // Returns the register corresponding to a local variable, or 0 if no
82         // such register exists. Registers returned by registerFor do not
83         // require explicit reference counting.
84         RegisterID* registerFor(const Identifier&);
85 
86         bool willResolveToArguments(const Identifier&);
87         RegisterID* uncheckedRegisterForArguments();
88 
89         // Behaves as registerFor does, but ignores dynamic scope as
90         // dynamic scope should not interfere with const initialisation
91         RegisterID* constRegisterFor(const Identifier&);
92 
93         // Searches the scope chain in an attempt to  statically locate the requested
94         // property.  Returns false if for any reason the property cannot be safely
95         // optimised at all.  Otherwise it will return the index and depth of the
96         // VariableObject that defines the property.  If the property cannot be found
97         // statically, depth will contain the depth of the scope chain where dynamic
98         // lookup must begin.
99         //
100         // NB: depth does _not_ include the local scope.  eg. a depth of 0 refers
101         // to the scope containing this codeblock.
102         bool findScopedProperty(const Identifier&, int& index, size_t& depth, bool forWriting, JSObject*& globalObject);
103 
104         // Returns the register storing "this"
thisRegister()105         RegisterID* thisRegister() { return &m_thisRegister; }
106 
107         bool isLocal(const Identifier&);
108         bool isLocalConstant(const Identifier&);
109 
110         // Returns the next available temporary register. Registers returned by
111         // newTemporary require a modified form of reference counting: any
112         // register with a refcount of 0 is considered "available", meaning that
113         // the next instruction may overwrite it.
114         RegisterID* newTemporary();
115 
116         RegisterID* highestUsedRegister();
117 
118         // The same as newTemporary(), but this function returns "suggestion" if
119         // "suggestion" is a temporary. This function is helpful in situations
120         // where you've put "suggestion" in a RefPtr, but you'd like to allow
121         // the next instruction to overwrite it anyway.
newTemporaryOr(RegisterID * suggestion)122         RegisterID* newTemporaryOr(RegisterID* suggestion) { return suggestion->isTemporary() ? suggestion : newTemporary(); }
123 
124         // Functions for handling of dst register
125 
ignoredResult()126         RegisterID* ignoredResult() { return &m_ignoredResultRegister; }
127 
128         // Returns a place to write intermediate values of an operation
129         // which reuses dst if it is safe to do so.
tempDestination(RegisterID * dst)130         RegisterID* tempDestination(RegisterID* dst)
131         {
132             return (dst && dst != ignoredResult() && dst->isTemporary()) ? dst : newTemporary();
133         }
134 
135         // Returns the place to write the final output of an operation.
136         RegisterID* finalDestination(RegisterID* originalDst, RegisterID* tempDst = 0)
137         {
138             if (originalDst && originalDst != ignoredResult())
139                 return originalDst;
140             ASSERT(tempDst != ignoredResult());
141             if (tempDst && tempDst->isTemporary())
142                 return tempDst;
143             return newTemporary();
144         }
145 
destinationForAssignResult(RegisterID * dst)146         RegisterID* destinationForAssignResult(RegisterID* dst)
147         {
148             if (dst && dst != ignoredResult() && m_codeBlock->needsFullScopeChain())
149                 return dst->isTemporary() ? dst : newTemporary();
150             return 0;
151         }
152 
153         // Moves src to dst if dst is not null and is different from src, otherwise just returns src.
moveToDestinationIfNeeded(RegisterID * dst,RegisterID * src)154         RegisterID* moveToDestinationIfNeeded(RegisterID* dst, RegisterID* src)
155         {
156             return dst == ignoredResult() ? 0 : (dst && dst != src) ? emitMove(dst, src) : src;
157         }
158 
159         PassRefPtr<LabelScope> newLabelScope(LabelScope::Type, const Identifier* = 0);
160         PassRefPtr<Label> newLabel();
161 
162         // The emitNode functions are just syntactic sugar for calling
163         // Node::emitCode. These functions accept a 0 for the register,
164         // meaning that the node should allocate a register, or ignoredResult(),
165         // meaning that the node need not put the result in a register.
166         // Other emit functions do not accept 0 or ignoredResult().
emitNode(RegisterID * dst,Node * n)167         RegisterID* emitNode(RegisterID* dst, Node* n)
168         {
169             // Node::emitCode assumes that dst, if provided, is either a local or a referenced temporary.
170             ASSERT(!dst || dst == ignoredResult() || !dst->isTemporary() || dst->refCount());
171             if (!m_codeBlock->numberOfLineInfos() || m_codeBlock->lastLineInfo().lineNumber != n->lineNo()) {
172                 LineInfo info = { instructions().size(), n->lineNo() };
173                 m_codeBlock->addLineInfo(info);
174             }
175             if (m_emitNodeDepth >= s_maxEmitNodeDepth)
176                 return emitThrowExpressionTooDeepException();
177             ++m_emitNodeDepth;
178             RegisterID* r = n->emitBytecode(*this, dst);
179             --m_emitNodeDepth;
180             return r;
181         }
182 
emitNode(Node * n)183         RegisterID* emitNode(Node* n)
184         {
185             return emitNode(0, n);
186         }
187 
emitExpressionInfo(unsigned divot,unsigned startOffset,unsigned endOffset)188         void emitExpressionInfo(unsigned divot, unsigned startOffset, unsigned endOffset)
189         {
190             divot -= m_codeBlock->sourceOffset();
191             if (divot > ExpressionRangeInfo::MaxDivot) {
192                 // Overflow has occurred, we can only give line number info for errors for this region
193                 divot = 0;
194                 startOffset = 0;
195                 endOffset = 0;
196             } else if (startOffset > ExpressionRangeInfo::MaxOffset) {
197                 // If the start offset is out of bounds we clear both offsets
198                 // so we only get the divot marker.  Error message will have to be reduced
199                 // to line and column number.
200                 startOffset = 0;
201                 endOffset = 0;
202             } else if (endOffset > ExpressionRangeInfo::MaxOffset) {
203                 // The end offset is only used for additional context, and is much more likely
204                 // to overflow (eg. function call arguments) so we are willing to drop it without
205                 // dropping the rest of the range.
206                 endOffset = 0;
207             }
208 
209             ExpressionRangeInfo info;
210             info.instructionOffset = instructions().size();
211             info.divotPoint = divot;
212             info.startOffset = startOffset;
213             info.endOffset = endOffset;
214             m_codeBlock->addExpressionInfo(info);
215         }
216 
emitGetByIdExceptionInfo(OpcodeID opcodeID)217         void emitGetByIdExceptionInfo(OpcodeID opcodeID)
218         {
219             // Only op_construct and op_instanceof need exception info for
220             // a preceding op_get_by_id.
221             ASSERT(opcodeID == op_construct || opcodeID == op_instanceof);
222             GetByIdExceptionInfo info;
223             info.bytecodeOffset = instructions().size();
224             info.isOpConstruct = (opcodeID == op_construct);
225             m_codeBlock->addGetByIdExceptionInfo(info);
226         }
227 
leftHandSideNeedsCopy(bool rightHasAssignments,bool rightIsPure)228         ALWAYS_INLINE bool leftHandSideNeedsCopy(bool rightHasAssignments, bool rightIsPure)
229         {
230             return (m_codeType != FunctionCode || m_codeBlock->needsFullScopeChain() || rightHasAssignments) && !rightIsPure;
231         }
232 
emitNodeForLeftHandSide(ExpressionNode * n,bool rightHasAssignments,bool rightIsPure)233         ALWAYS_INLINE PassRefPtr<RegisterID> emitNodeForLeftHandSide(ExpressionNode* n, bool rightHasAssignments, bool rightIsPure)
234         {
235             if (leftHandSideNeedsCopy(rightHasAssignments, rightIsPure)) {
236                 PassRefPtr<RegisterID> dst = newTemporary();
237                 emitNode(dst.get(), n);
238                 return dst;
239             }
240 
241             return PassRefPtr<RegisterID>(emitNode(n));
242         }
243 
244         RegisterID* emitLoad(RegisterID* dst, bool);
245         RegisterID* emitLoad(RegisterID* dst, double);
246         RegisterID* emitLoad(RegisterID* dst, const Identifier&);
247         RegisterID* emitLoad(RegisterID* dst, JSValue);
248 
249         RegisterID* emitUnaryOp(OpcodeID, RegisterID* dst, RegisterID* src);
250         RegisterID* emitBinaryOp(OpcodeID, RegisterID* dst, RegisterID* src1, RegisterID* src2, OperandTypes);
251         RegisterID* emitEqualityOp(OpcodeID, RegisterID* dst, RegisterID* src1, RegisterID* src2);
252         RegisterID* emitUnaryNoDstOp(OpcodeID, RegisterID* src);
253 
254         RegisterID* emitNewObject(RegisterID* dst);
255         RegisterID* emitNewArray(RegisterID* dst, ElementNode*); // stops at first elision
256 
257         RegisterID* emitNewFunction(RegisterID* dst, FuncDeclNode* func);
258         RegisterID* emitNewFunctionExpression(RegisterID* dst, FuncExprNode* func);
259         RegisterID* emitNewRegExp(RegisterID* dst, RegExp* regExp);
260 
261         RegisterID* emitMove(RegisterID* dst, RegisterID* src);
262 
emitToJSNumber(RegisterID * dst,RegisterID * src)263         RegisterID* emitToJSNumber(RegisterID* dst, RegisterID* src) { return emitUnaryOp(op_to_jsnumber, dst, src); }
264         RegisterID* emitPreInc(RegisterID* srcDst);
265         RegisterID* emitPreDec(RegisterID* srcDst);
266         RegisterID* emitPostInc(RegisterID* dst, RegisterID* srcDst);
267         RegisterID* emitPostDec(RegisterID* dst, RegisterID* srcDst);
268 
269         RegisterID* emitInstanceOf(RegisterID* dst, RegisterID* value, RegisterID* base, RegisterID* basePrototype);
emitTypeOf(RegisterID * dst,RegisterID * src)270         RegisterID* emitTypeOf(RegisterID* dst, RegisterID* src) { return emitUnaryOp(op_typeof, dst, src); }
emitIn(RegisterID * dst,RegisterID * property,RegisterID * base)271         RegisterID* emitIn(RegisterID* dst, RegisterID* property, RegisterID* base) { return emitBinaryOp(op_in, dst, property, base, OperandTypes()); }
272 
273         RegisterID* emitResolve(RegisterID* dst, const Identifier& property);
274         RegisterID* emitGetScopedVar(RegisterID* dst, size_t skip, int index, JSValue globalObject);
275         RegisterID* emitPutScopedVar(size_t skip, int index, RegisterID* value, JSValue globalObject);
276 
277         RegisterID* emitResolveBase(RegisterID* dst, const Identifier& property);
278         RegisterID* emitResolveWithBase(RegisterID* baseDst, RegisterID* propDst, const Identifier& property);
279 
280         void emitMethodCheck();
281 
282         RegisterID* emitGetById(RegisterID* dst, RegisterID* base, const Identifier& property);
283         RegisterID* emitPutById(RegisterID* base, const Identifier& property, RegisterID* value);
284         RegisterID* emitDeleteById(RegisterID* dst, RegisterID* base, const Identifier&);
285         RegisterID* emitGetByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
286         RegisterID* emitPutByVal(RegisterID* base, RegisterID* property, RegisterID* value);
287         RegisterID* emitDeleteByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
288         RegisterID* emitPutByIndex(RegisterID* base, unsigned index, RegisterID* value);
289         RegisterID* emitPutGetter(RegisterID* base, const Identifier& property, RegisterID* value);
290         RegisterID* emitPutSetter(RegisterID* base, const Identifier& property, RegisterID* value);
291 
292         RegisterID* emitCall(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
293         RegisterID* emitCallEval(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
294         RegisterID* emitCallVarargs(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, RegisterID* argCount, unsigned divot, unsigned startOffset, unsigned endOffset);
295         RegisterID* emitLoadVarargs(RegisterID* argCountDst, RegisterID* args);
296 
297         RegisterID* emitReturn(RegisterID* src);
emitEnd(RegisterID * src)298         RegisterID* emitEnd(RegisterID* src) { return emitUnaryNoDstOp(op_end, src); }
299 
300         RegisterID* emitConstruct(RegisterID* dst, RegisterID* func, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
301         RegisterID* emitStrcat(RegisterID* dst, RegisterID* src, int count);
302         void emitToPrimitive(RegisterID* dst, RegisterID* src);
303 
304         PassRefPtr<Label> emitLabel(Label*);
305         PassRefPtr<Label> emitJump(Label* target);
306         PassRefPtr<Label> emitJumpIfTrue(RegisterID* cond, Label* target);
307         PassRefPtr<Label> emitJumpIfFalse(RegisterID* cond, Label* target);
308         PassRefPtr<Label> emitJumpIfNotFunctionCall(RegisterID* cond, Label* target);
309         PassRefPtr<Label> emitJumpIfNotFunctionApply(RegisterID* cond, Label* target);
310         PassRefPtr<Label> emitJumpScopes(Label* target, int targetScopeDepth);
311 
312         PassRefPtr<Label> emitJumpSubroutine(RegisterID* retAddrDst, Label*);
313         void emitSubroutineReturn(RegisterID* retAddrSrc);
314 
emitGetPropertyNames(RegisterID * dst,RegisterID * base)315         RegisterID* emitGetPropertyNames(RegisterID* dst, RegisterID* base) { return emitUnaryOp(op_get_pnames, dst, base); }
316         RegisterID* emitNextPropertyName(RegisterID* dst, RegisterID* iter, Label* target);
317 
318         RegisterID* emitCatch(RegisterID*, Label* start, Label* end);
emitThrow(RegisterID * exc)319         void emitThrow(RegisterID* exc) { emitUnaryNoDstOp(op_throw, exc); }
320         RegisterID* emitNewError(RegisterID* dst, ErrorType type, JSValue message);
321         void emitPushNewScope(RegisterID* dst, Identifier& property, RegisterID* value);
322 
323         RegisterID* emitPushScope(RegisterID* scope);
324         void emitPopScope();
325 
326         void emitDebugHook(DebugHookID, int firstLine, int lastLine);
327 
scopeDepth()328         int scopeDepth() { return m_dynamicScopeDepth + m_finallyDepth; }
hasFinaliser()329         bool hasFinaliser() { return m_finallyDepth != 0; }
330 
331         void pushFinallyContext(Label* target, RegisterID* returnAddrDst);
332         void popFinallyContext();
333 
334         LabelScope* breakTarget(const Identifier&);
335         LabelScope* continueTarget(const Identifier&);
336 
337         void beginSwitch(RegisterID*, SwitchInfo::SwitchType);
338         void endSwitch(uint32_t clauseCount, RefPtr<Label>*, ExpressionNode**, Label* defaultLabel, int32_t min, int32_t range);
339 
codeType()340         CodeType codeType() const { return m_codeType; }
341 
setRegeneratingForExceptionInfo(CodeBlock * originalCodeBlock)342         void setRegeneratingForExceptionInfo(CodeBlock* originalCodeBlock)
343         {
344             m_regeneratingForExceptionInfo = true;
345             m_codeBlockBeingRegeneratedFrom = originalCodeBlock;
346         }
347 
348     private:
349         void emitOpcode(OpcodeID);
350         void retrieveLastBinaryOp(int& dstIndex, int& src1Index, int& src2Index);
351         void retrieveLastUnaryOp(int& dstIndex, int& srcIndex);
352         void rewindBinaryOp();
353         void rewindUnaryOp();
354 
355         PassRefPtr<Label> emitComplexJumpScopes(Label* target, ControlFlowContext* topScope, ControlFlowContext* bottomScope);
356 
357         typedef HashMap<EncodedJSValue, unsigned, EncodedJSValueHash, EncodedJSValueHashTraits> JSValueMap;
358 
359         struct IdentifierMapIndexHashTraits {
360             typedef int TraitType;
361             typedef IdentifierMapIndexHashTraits StorageTraits;
emptyValueIdentifierMapIndexHashTraits362             static int emptyValue() { return std::numeric_limits<int>::max(); }
363             static const bool emptyValueIsZero = false;
364             static const bool needsDestruction = false;
365             static const bool needsRef = false;
366         };
367 
368         typedef HashMap<RefPtr<UString::Rep>, int, IdentifierRepHash, HashTraits<RefPtr<UString::Rep> >, IdentifierMapIndexHashTraits> IdentifierMap;
369         typedef HashMap<double, JSValue> NumberMap;
370         typedef HashMap<UString::Rep*, JSString*, IdentifierRepHash> IdentifierStringMap;
371 
372         RegisterID* emitCall(OpcodeID, RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
373 
374         RegisterID* newRegister();
375 
376         // Returns the RegisterID corresponding to ident.
addVar(const Identifier & ident,bool isConstant)377         RegisterID* addVar(const Identifier& ident, bool isConstant)
378         {
379             RegisterID* local;
380             addVar(ident, isConstant, local);
381             return local;
382         }
383         // Returns true if a new RegisterID was added, false if a pre-existing RegisterID was re-used.
384         bool addVar(const Identifier&, bool isConstant, RegisterID*&);
385 
386         // Returns the RegisterID corresponding to ident.
addGlobalVar(const Identifier & ident,bool isConstant)387         RegisterID* addGlobalVar(const Identifier& ident, bool isConstant)
388         {
389             RegisterID* local;
390             addGlobalVar(ident, isConstant, local);
391             return local;
392         }
393         // Returns true if a new RegisterID was added, false if a pre-existing RegisterID was re-used.
394         bool addGlobalVar(const Identifier&, bool isConstant, RegisterID*&);
395 
396         RegisterID* addParameter(const Identifier&);
397 
398         void preserveLastVar();
399 
registerFor(int index)400         RegisterID& registerFor(int index)
401         {
402             if (index >= 0)
403                 return m_calleeRegisters[index];
404 
405             if (index == RegisterFile::OptionalCalleeArguments)
406                 return m_argumentsRegister;
407 
408             if (m_parameters.size()) {
409                 ASSERT(!m_globals.size());
410                 return m_parameters[index + m_parameters.size() + RegisterFile::CallFrameHeaderSize];
411             }
412 
413             return m_globals[-index - 1];
414         }
415 
416         unsigned addConstant(FuncDeclNode*);
417         unsigned addConstant(FuncExprNode*);
418         unsigned addConstant(const Identifier&);
419         RegisterID* addConstantValue(JSValue);
420         unsigned addRegExp(RegExp*);
421 
instructions()422         Vector<Instruction>& instructions() { return m_codeBlock->instructions(); }
symbolTable()423         SymbolTable& symbolTable() { return *m_symbolTable; }
424 
shouldOptimizeLocals()425         bool shouldOptimizeLocals() { return (m_codeType != EvalCode) && !m_dynamicScopeDepth; }
canOptimizeNonLocals()426         bool canOptimizeNonLocals() { return (m_codeType == FunctionCode) && !m_dynamicScopeDepth && !m_codeBlock->usesEval(); }
427 
428         RegisterID* emitThrowExpressionTooDeepException();
429 
430         void createArgumentsIfNecessary();
431 
432         bool m_shouldEmitDebugHooks;
433         bool m_shouldEmitProfileHooks;
434 
435         const ScopeChain* m_scopeChain;
436         SymbolTable* m_symbolTable;
437 
438         ScopeNode* m_scopeNode;
439         CodeBlock* m_codeBlock;
440 
441         // Some of these objects keep pointers to one another. They are arranged
442         // to ensure a sane destruction order that avoids references to freed memory.
443         HashSet<RefPtr<UString::Rep>, IdentifierRepHash> m_functions;
444         RegisterID m_ignoredResultRegister;
445         RegisterID m_thisRegister;
446         RegisterID m_argumentsRegister;
447         int m_activationRegisterIndex;
448         WTF::SegmentedVector<RegisterID, 32> m_constantPoolRegisters;
449         WTF::SegmentedVector<RegisterID, 32> m_calleeRegisters;
450         WTF::SegmentedVector<RegisterID, 32> m_parameters;
451         WTF::SegmentedVector<RegisterID, 32> m_globals;
452         WTF::SegmentedVector<Label, 32> m_labels;
453         WTF::SegmentedVector<LabelScope, 8> m_labelScopes;
454         RefPtr<RegisterID> m_lastVar;
455         int m_finallyDepth;
456         int m_dynamicScopeDepth;
457         int m_baseScopeDepth;
458         CodeType m_codeType;
459 
460         Vector<ControlFlowContext> m_scopeContextStack;
461         Vector<SwitchInfo> m_switchContextStack;
462 
463         int m_nextGlobalIndex;
464         int m_nextParameterIndex;
465         int m_firstConstantIndex;
466         int m_nextConstantOffset;
467         unsigned m_globalConstantIndex;
468 
469         int m_globalVarStorageOffset;
470 
471         // Constant pool
472         IdentifierMap m_identifierMap;
473         JSValueMap m_jsValueMap;
474         NumberMap m_numberMap;
475         IdentifierStringMap m_stringMap;
476 
477         JSGlobalData* m_globalData;
478 
479         OpcodeID m_lastOpcodeID;
480 
481         unsigned m_emitNodeDepth;
482 
483         bool m_regeneratingForExceptionInfo;
484         CodeBlock* m_codeBlockBeingRegeneratedFrom;
485 
486         static const unsigned s_maxEmitNodeDepth = 5000;
487     };
488 
489 }
490 
491 #endif // BytecodeGenerator_h
492