/*
 * Copyright (C) 2008, 2009, 2012 Apple Inc. All rights reserved.
 * Copyright (C) 2008 Cameron Zwarich <cwzwarich@uwaterloo.ca>
 * Copyright (C) 2012 Igalia, S.L.
 *
 * 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 BytecodeGenerator_h
#define BytecodeGenerator_h

#include "CodeBlock.h"
#include <wtf/HashTraits.h>
#include "Instruction.h"
#include "Label.h"
#include "LabelScope.h"
#include "Interpreter.h"
#include "RegisterID.h"
#include "SymbolTable.h"
#include "Debugger.h"
#include "Nodes.h"
#include <wtf/PassRefPtr.h>
#include <wtf/SegmentedVector.h>
#include <wtf/Vector.h>

namespace JSC {

    class Identifier;
    class Label;
    class ScopeChainNode;

    class CallArguments {
    public:
        CallArguments(BytecodeGenerator& generator, ArgumentsNode* argumentsNode);

        RegisterID* thisRegister() { return m_argv[0].get(); }
        RegisterID* argumentRegister(unsigned i) { return m_argv[i + 1].get(); }
        unsigned registerOffset() { return m_argv.last()->index() + CallFrame::offsetFor(argumentCountIncludingThis()); }
        unsigned argumentCountIncludingThis() { return m_argv.size(); }
        RegisterID* profileHookRegister() { return m_profileHookRegister.get(); }
        ArgumentsNode* argumentsNode() { return m_argumentsNode; }

    private:
        void newArgument(BytecodeGenerator&);

        RefPtr<RegisterID> m_profileHookRegister;
        ArgumentsNode* m_argumentsNode;
        Vector<RefPtr<RegisterID>, 8> m_argv;
    };

    struct FinallyContext {
        StatementNode* finallyBlock;
        unsigned scopeContextStackSize;
        unsigned switchContextStackSize;
        unsigned forInContextStackSize;
        unsigned labelScopesSize;
        int finallyDepth;
        int dynamicScopeDepth;
    };

    struct ControlFlowContext {
        bool isFinallyBlock;
        FinallyContext finallyContext;
    };

    struct ForInContext {
        RefPtr<RegisterID> expectedSubscriptRegister;
        RefPtr<RegisterID> iterRegister;
        RefPtr<RegisterID> indexRegister;
        RefPtr<RegisterID> propertyRegister;
    };

    class ResolveResult {
    public:
        enum Flags {
            // The property is locally bound, in a register.
            RegisterFlag = 0x1,
            // We need to traverse the scope chain at runtime, checking for
            // non-strict eval and/or `with' nodes.
            DynamicFlag = 0x2,
            // The property was resolved to a definite location, and the
            // identifier is not needed any more.
            StaticFlag = 0x4,
            // Once we have the base object, the property will be located at a
            // known index.
            IndexedFlag = 0x8,
            // Skip some number of objects in the scope chain, given by "depth".
            ScopedFlag = 0x10,
            // The resolved binding is immutable.
            ReadOnlyFlag = 0x20,
            // The base object is the global object.
            GlobalFlag = 0x40,
            // The property is being watched, so writes should be special.
            WatchedFlag = 0x80
        };
        enum Type {
            // The property is local, and stored in a register.
            Register = RegisterFlag | StaticFlag,
            // A read-only local, created by "const".
            ReadOnlyRegister = RegisterFlag | ReadOnlyFlag | StaticFlag,
            // The property is statically scoped free variable. Its coordinates
            // are in "index" and "depth".
            Lexical = IndexedFlag | ScopedFlag | StaticFlag,
            // A read-only Lexical, created by "const".
            ReadOnlyLexical = IndexedFlag | ScopedFlag | ReadOnlyFlag | StaticFlag,
            // The property was not bound lexically, so at runtime we should
            // look directly in the global object.
            Global = GlobalFlag,
            // Like Global, but we could actually resolve the property to a
            // DontDelete property in the global object, for instance, any
            // binding created with "var" at the top level. At runtime we'll
            // just index into the global object.
            IndexedGlobal = IndexedFlag | GlobalFlag | StaticFlag,
            // Like IndexedGlobal, but the property is being watched.
            WatchedIndexedGlobal = IndexedFlag | GlobalFlag | StaticFlag | WatchedFlag,
            // Like IndexedGlobal, but the property is also read-only, like NaN,
            // Infinity, or undefined.
            ReadOnlyIndexedGlobal = IndexedFlag | ReadOnlyFlag | GlobalFlag | StaticFlag,
            // The property could not be resolved statically, due to the
            // presence of `with' blocks. At runtime we'll have to walk the
            // scope chain. ScopedFlag is set to indicate that "depth" will
            // hold some number of nodes to skip in the scope chain, before
            // beginning the search.
            Dynamic = DynamicFlag | ScopedFlag,
            // The property was located as a statically scoped free variable,
            // but while traversing the scope chain, there was an intermediate
            // activation that used non-strict `eval'. At runtime we'll have to
            // check for the absence of this property in those intervening
            // scopes.
            DynamicLexical = DynamicFlag | IndexedFlag | ScopedFlag,
            // Like ReadOnlyLexical, but with intervening non-strict `eval'.
            DynamicReadOnlyLexical = DynamicFlag | IndexedFlag | ScopedFlag | ReadOnlyFlag,
            // Like Global, but with intervening non-strict `eval'. As with 
            // Dynamic, ScopeFlag is set to indicate that "depth" does indeed
            // store a number of frames to skip before doing the dynamic checks.
            DynamicGlobal = DynamicFlag | GlobalFlag | ScopedFlag,
            // Like IndexedGlobal, but with intervening non-strict `eval'.
            DynamicIndexedGlobal = DynamicFlag | IndexedFlag | GlobalFlag | ScopedFlag,
            // Like ReadOnlyIndexedGlobal, but with intervening non-strict
            // `eval'.
            DynamicReadOnlyIndexedGlobal = DynamicFlag | IndexedFlag | ReadOnlyFlag | GlobalFlag | ScopedFlag,
        };

        static ResolveResult registerResolve(RegisterID *local, unsigned flags)
        {
            return ResolveResult(Register | flags, local, missingSymbolMarker(), 0, 0);
        }
        static ResolveResult dynamicResolve(size_t depth)
        {
            return ResolveResult(Dynamic, 0, missingSymbolMarker(), depth, 0);
        }
        static ResolveResult lexicalResolve(int index, size_t depth, unsigned flags)
        {
            unsigned type = (flags & DynamicFlag) ? DynamicLexical : Lexical;
            return ResolveResult(type | flags, 0, index, depth, 0);
        }
        static ResolveResult indexedGlobalResolve(int index, JSObject *globalObject, unsigned flags)
        {
            return ResolveResult(IndexedGlobal | flags, 0, index, 0, globalObject);
        }
        static ResolveResult dynamicIndexedGlobalResolve(int index, size_t depth, JSObject *globalObject, unsigned flags)
        {
            return ResolveResult(DynamicIndexedGlobal | flags, 0, index, depth, globalObject);
        }
        static ResolveResult globalResolve(JSObject *globalObject)
        {
            return ResolveResult(Global, 0, missingSymbolMarker(), 0, globalObject);
        }
        static ResolveResult dynamicGlobalResolve(size_t dynamicDepth, JSObject *globalObject)
        {
            return ResolveResult(DynamicGlobal, 0, missingSymbolMarker(), dynamicDepth, globalObject);
        }

        unsigned type() const { return m_type; }
        // Returns the register corresponding to a local variable, or 0 if no
        // such register exists. Registers returned by ResolveResult::local() do
        // not require explicit reference counting.
        RegisterID* local() const { return m_local; }
        int index() const { ASSERT (isIndexed() || isRegister()); return m_index; }
        size_t depth() const { ASSERT(isScoped()); return m_depth; }
        JSObject* globalObject() const { ASSERT(isGlobal()); ASSERT(m_globalObject); return m_globalObject; }
        WriteBarrier<Unknown>* registerPointer() const;

        bool isRegister() const { return m_type & RegisterFlag; }
        bool isDynamic() const { return m_type & DynamicFlag; }
        bool isStatic() const { return m_type & StaticFlag; }
        bool isIndexed() const { return m_type & IndexedFlag; }
        bool isScoped() const { return m_type & ScopedFlag; }
        bool isReadOnly() const { return (m_type & ReadOnlyFlag) && !isDynamic(); }
        bool isGlobal() const { return m_type & GlobalFlag; }

    private:
        ResolveResult(unsigned type, RegisterID* local, int index, size_t depth, JSObject* globalObject)
            : m_type(type)
            , m_index(index)
            , m_local(local)
            , m_depth(depth)
            , m_globalObject(globalObject)
        {
#ifndef NDEBUG
            checkValidity();
#endif
        }

#ifndef NDEBUG
        void checkValidity();
#endif

        unsigned m_type;
        int m_index; // Index in scope, if IndexedFlag is set
        RegisterID* m_local; // Local register, if RegisterFlag is set
        size_t m_depth; // Depth in scope chain, if ScopedFlag is set
        JSObject* m_globalObject; // If GlobalFlag is set.
    };

    class BytecodeGenerator {
        WTF_MAKE_FAST_ALLOCATED;
    public:
        typedef DeclarationStacks::VarStack VarStack;
        typedef DeclarationStacks::FunctionStack FunctionStack;

        JS_EXPORT_PRIVATE static void setDumpsGeneratedCode(bool dumpsGeneratedCode);
        static bool dumpsGeneratedCode();

        BytecodeGenerator(ProgramNode*, ScopeChainNode*, SymbolTable*, ProgramCodeBlock*, CompilationKind);
        BytecodeGenerator(FunctionBodyNode*, ScopeChainNode*, SymbolTable*, CodeBlock*, CompilationKind);
        BytecodeGenerator(EvalNode*, ScopeChainNode*, SymbolTable*, EvalCodeBlock*, CompilationKind);

        ~BytecodeGenerator();
        
        JSGlobalData* globalData() const { return m_globalData; }
        const CommonIdentifiers& propertyNames() const { return *m_globalData->propertyNames; }

        bool isConstructor() { return m_codeBlock->m_isConstructor; }

        JSObject* generate();

        bool isArgumentNumber(const Identifier&, int);

        void setIsNumericCompareFunction(bool isNumericCompareFunction);

        bool willResolveToArguments(const Identifier&);
        RegisterID* uncheckedRegisterForArguments();

        // Resolve an identifier, given the current compile-time scope chain.
        ResolveResult resolve(const Identifier&);
        // Behaves as resolve does, but ignores dynamic scope as
        // dynamic scope should not interfere with const initialisation
        ResolveResult resolveConstDecl(const Identifier&);

        // Returns the register storing "this"
        RegisterID* thisRegister() { return &m_thisRegister; }

        // Returns the next available temporary register. Registers returned by
        // newTemporary require a modified form of reference counting: any
        // register with a refcount of 0 is considered "available", meaning that
        // the next instruction may overwrite it.
        RegisterID* newTemporary();

        RegisterID* highestUsedRegister();

        // The same as newTemporary(), but this function returns "suggestion" if
        // "suggestion" is a temporary. This function is helpful in situations
        // where you've put "suggestion" in a RefPtr, but you'd like to allow
        // the next instruction to overwrite it anyway.
        RegisterID* newTemporaryOr(RegisterID* suggestion) { return suggestion->isTemporary() ? suggestion : newTemporary(); }

        // Functions for handling of dst register

        RegisterID* ignoredResult() { return &m_ignoredResultRegister; }

        // Returns a place to write intermediate values of an operation
        // which reuses dst if it is safe to do so.
        RegisterID* tempDestination(RegisterID* dst)
        {
            return (dst && dst != ignoredResult() && dst->isTemporary()) ? dst : newTemporary();
        }

        // Returns the place to write the final output of an operation.
        RegisterID* finalDestination(RegisterID* originalDst, RegisterID* tempDst = 0)
        {
            if (originalDst && originalDst != ignoredResult())
                return originalDst;
            ASSERT(tempDst != ignoredResult());
            if (tempDst && tempDst->isTemporary())
                return tempDst;
            return newTemporary();
        }

        // Returns the place to write the final output of an operation.
        RegisterID* finalDestinationOrIgnored(RegisterID* originalDst, RegisterID* tempDst = 0)
        {
            if (originalDst)
                return originalDst;
            ASSERT(tempDst != ignoredResult());
            if (tempDst && tempDst->isTemporary())
                return tempDst;
            return newTemporary();
        }

        RegisterID* destinationForAssignResult(RegisterID* dst)
        {
            if (dst && dst != ignoredResult() && m_codeBlock->needsFullScopeChain())
                return dst->isTemporary() ? dst : newTemporary();
            return 0;
        }

        // Moves src to dst if dst is not null and is different from src, otherwise just returns src.
        RegisterID* moveToDestinationIfNeeded(RegisterID* dst, RegisterID* src)
        {
            return dst == ignoredResult() ? 0 : (dst && dst != src) ? emitMove(dst, src) : src;
        }

        PassRefPtr<LabelScope> newLabelScope(LabelScope::Type, const Identifier* = 0);
        PassRefPtr<Label> newLabel();

        // The emitNode functions are just syntactic sugar for calling
        // Node::emitCode. These functions accept a 0 for the register,
        // meaning that the node should allocate a register, or ignoredResult(),
        // meaning that the node need not put the result in a register.
        // Other emit functions do not accept 0 or ignoredResult().
        RegisterID* emitNode(RegisterID* dst, Node* n)
        {
            // Node::emitCode assumes that dst, if provided, is either a local or a referenced temporary.
            ASSERT(!dst || dst == ignoredResult() || !dst->isTemporary() || dst->refCount());
            addLineInfo(n->lineNo());
            return m_stack.recursionCheck()
                ? n->emitBytecode(*this, dst)
                : emitThrowExpressionTooDeepException();
        }

        RegisterID* emitNode(Node* n)
        {
            return emitNode(0, n);
        }

        void emitNodeInConditionContext(ExpressionNode* n, Label* trueTarget, Label* falseTarget, bool fallThroughMeansTrue)
        {
            addLineInfo(n->lineNo());
            if (m_stack.recursionCheck())
                n->emitBytecodeInConditionContext(*this, trueTarget, falseTarget, fallThroughMeansTrue);
            else
                emitThrowExpressionTooDeepException();
        }

        void emitExpressionInfo(unsigned divot, unsigned startOffset, unsigned endOffset)
        {
            if (!m_shouldEmitRichSourceInfo)
                return;

            divot -= m_codeBlock->sourceOffset();
            if (divot > ExpressionRangeInfo::MaxDivot) {
                // Overflow has occurred, we can only give line number info for errors for this region
                divot = 0;
                startOffset = 0;
                endOffset = 0;
            } else if (startOffset > ExpressionRangeInfo::MaxOffset) {
                // If the start offset is out of bounds we clear both offsets
                // so we only get the divot marker.  Error message will have to be reduced
                // to line and column number.
                startOffset = 0;
                endOffset = 0;
            } else if (endOffset > ExpressionRangeInfo::MaxOffset) {
                // The end offset is only used for additional context, and is much more likely
                // to overflow (eg. function call arguments) so we are willing to drop it without
                // dropping the rest of the range.
                endOffset = 0;
            }
            
            ExpressionRangeInfo info;
            info.instructionOffset = instructions().size();
            info.divotPoint = divot;
            info.startOffset = startOffset;
            info.endOffset = endOffset;
            m_codeBlock->addExpressionInfo(info);
        }

        ALWAYS_INLINE bool leftHandSideNeedsCopy(bool rightHasAssignments, bool rightIsPure)
        {
            return (m_codeType != FunctionCode || m_codeBlock->needsFullScopeChain() || rightHasAssignments) && !rightIsPure;
        }

        ALWAYS_INLINE PassRefPtr<RegisterID> emitNodeForLeftHandSide(ExpressionNode* n, bool rightHasAssignments, bool rightIsPure)
        {
            if (leftHandSideNeedsCopy(rightHasAssignments, rightIsPure)) {
                PassRefPtr<RegisterID> dst = newTemporary();
                emitNode(dst.get(), n);
                return dst;
            }

            return emitNode(n);
        }

        RegisterID* emitLoad(RegisterID* dst, bool);
        RegisterID* emitLoad(RegisterID* dst, double);
        RegisterID* emitLoad(RegisterID* dst, const Identifier&);
        RegisterID* emitLoad(RegisterID* dst, JSValue);

        RegisterID* emitUnaryOp(OpcodeID, RegisterID* dst, RegisterID* src);
        RegisterID* emitBinaryOp(OpcodeID, RegisterID* dst, RegisterID* src1, RegisterID* src2, OperandTypes);
        RegisterID* emitEqualityOp(OpcodeID, RegisterID* dst, RegisterID* src1, RegisterID* src2);
        RegisterID* emitUnaryNoDstOp(OpcodeID, RegisterID* src);

        RegisterID* emitNewObject(RegisterID* dst);
        RegisterID* emitNewArray(RegisterID* dst, ElementNode*, unsigned length); // stops at first elision

        RegisterID* emitNewFunction(RegisterID* dst, FunctionBodyNode* body);
        RegisterID* emitLazyNewFunction(RegisterID* dst, FunctionBodyNode* body);
        RegisterID* emitNewFunctionInternal(RegisterID* dst, unsigned index, bool shouldNullCheck);
        RegisterID* emitNewFunctionExpression(RegisterID* dst, FuncExprNode* func);
        RegisterID* emitNewRegExp(RegisterID* dst, RegExp*);

        RegisterID* emitMove(RegisterID* dst, RegisterID* src);

        RegisterID* emitToJSNumber(RegisterID* dst, RegisterID* src) { return emitUnaryOp(op_to_jsnumber, dst, src); }
        RegisterID* emitPreInc(RegisterID* srcDst);
        RegisterID* emitPreDec(RegisterID* srcDst);
        RegisterID* emitPostInc(RegisterID* dst, RegisterID* srcDst);
        RegisterID* emitPostDec(RegisterID* dst, RegisterID* srcDst);

        void emitCheckHasInstance(RegisterID* base);
        RegisterID* emitInstanceOf(RegisterID* dst, RegisterID* value, RegisterID* base, RegisterID* basePrototype);
        RegisterID* emitTypeOf(RegisterID* dst, RegisterID* src) { return emitUnaryOp(op_typeof, dst, src); }
        RegisterID* emitIn(RegisterID* dst, RegisterID* property, RegisterID* base) { return emitBinaryOp(op_in, dst, property, base, OperandTypes()); }

        RegisterID* emitGetStaticVar(RegisterID* dst, const ResolveResult&, const Identifier&);
        RegisterID* emitPutStaticVar(const ResolveResult&, const Identifier&, RegisterID* value);

        RegisterID* emitResolve(RegisterID* dst, const ResolveResult&, const Identifier& property);
        RegisterID* emitResolveBase(RegisterID* dst, const ResolveResult&, const Identifier& property);
        RegisterID* emitResolveBaseForPut(RegisterID* dst, const ResolveResult&, const Identifier& property);
        RegisterID* emitResolveWithBase(RegisterID* baseDst, RegisterID* propDst, const ResolveResult&, const Identifier& property);
        RegisterID* emitResolveWithThis(RegisterID* baseDst, RegisterID* propDst, const ResolveResult&, const Identifier& property);

        void emitMethodCheck();

        RegisterID* emitGetById(RegisterID* dst, RegisterID* base, const Identifier& property);
        RegisterID* emitGetArgumentsLength(RegisterID* dst, RegisterID* base);
        RegisterID* emitPutById(RegisterID* base, const Identifier& property, RegisterID* value);
        RegisterID* emitDirectPutById(RegisterID* base, const Identifier& property, RegisterID* value);
        RegisterID* emitDeleteById(RegisterID* dst, RegisterID* base, const Identifier&);
        RegisterID* emitGetByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
        RegisterID* emitGetArgumentByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
        RegisterID* emitPutByVal(RegisterID* base, RegisterID* property, RegisterID* value);
        RegisterID* emitDeleteByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
        RegisterID* emitPutByIndex(RegisterID* base, unsigned index, RegisterID* value);
        void emitPutGetterSetter(RegisterID* base, const Identifier& property, RegisterID* getter, RegisterID* setter);

        RegisterID* emitCall(RegisterID* dst, RegisterID* func, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
        RegisterID* emitCallEval(RegisterID* dst, RegisterID* func, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
        RegisterID* emitCallVarargs(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, RegisterID* arguments, RegisterID* firstFreeRegister, RegisterID* profileHookRegister, unsigned divot, unsigned startOffset, unsigned endOffset);
        RegisterID* emitLoadVarargs(RegisterID* argCountDst, RegisterID* thisRegister, RegisterID* args);

        RegisterID* emitReturn(RegisterID* src);
        RegisterID* emitEnd(RegisterID* src) { return emitUnaryNoDstOp(op_end, src); }

        RegisterID* emitConstruct(RegisterID* dst, RegisterID* func, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
        RegisterID* emitStrcat(RegisterID* dst, RegisterID* src, int count);
        void emitToPrimitive(RegisterID* dst, RegisterID* src);

        PassRefPtr<Label> emitLabel(Label*);
        void emitLoopHint();
        PassRefPtr<Label> emitJump(Label* target);
        PassRefPtr<Label> emitJumpIfTrue(RegisterID* cond, Label* target);
        PassRefPtr<Label> emitJumpIfFalse(RegisterID* cond, Label* target);
        PassRefPtr<Label> emitJumpIfNotFunctionCall(RegisterID* cond, Label* target);
        PassRefPtr<Label> emitJumpIfNotFunctionApply(RegisterID* cond, Label* target);
        PassRefPtr<Label> emitJumpScopes(Label* target, int targetScopeDepth);

        RegisterID* emitGetPropertyNames(RegisterID* dst, RegisterID* base, RegisterID* i, RegisterID* size, Label* breakTarget);
        RegisterID* emitNextPropertyName(RegisterID* dst, RegisterID* base, RegisterID* i, RegisterID* size, RegisterID* iter, Label* target);

        RegisterID* emitCatch(RegisterID*, Label* start, Label* end);
        void emitThrow(RegisterID* exc)
        { 
            m_usesExceptions = true;
            emitUnaryNoDstOp(op_throw, exc);
        }

        void emitThrowReferenceError(const UString& message);

        void emitPushNewScope(RegisterID* dst, const Identifier& property, RegisterID* value);

        RegisterID* emitPushScope(RegisterID* scope);
        void emitPopScope();

        void emitDebugHook(DebugHookID, int firstLine, int lastLine);

        int scopeDepth() { return m_dynamicScopeDepth + m_finallyDepth; }
        bool hasFinaliser() { return m_finallyDepth != 0; }

        void pushFinallyContext(StatementNode* finallyBlock);
        void popFinallyContext();

        void pushOptimisedForIn(RegisterID* expectedBase, RegisterID* iter, RegisterID* index, RegisterID* propertyRegister)
        {
            ForInContext context = { expectedBase, iter, index, propertyRegister };
            m_forInContextStack.append(context);
        }

        void popOptimisedForIn()
        {
            m_forInContextStack.removeLast();
        }

        LabelScope* breakTarget(const Identifier&);
        LabelScope* continueTarget(const Identifier&);

        void beginSwitch(RegisterID*, SwitchInfo::SwitchType);
        void endSwitch(uint32_t clauseCount, RefPtr<Label>*, ExpressionNode**, Label* defaultLabel, int32_t min, int32_t range);

        CodeType codeType() const { return m_codeType; }

        bool shouldEmitProfileHooks() { return m_shouldEmitProfileHooks; }
        
        bool isStrictMode() const { return m_codeBlock->isStrictMode(); }
        
        ScopeChainNode* scopeChain() const { return m_scopeChain.get(); }

    private:
        friend class Label;
        
        void emitOpcode(OpcodeID);
        ValueProfile* emitProfiledOpcode(OpcodeID);
        void retrieveLastBinaryOp(int& dstIndex, int& src1Index, int& src2Index);
        void retrieveLastUnaryOp(int& dstIndex, int& srcIndex);
        void retrieveLastUnaryOp(WriteBarrier<Unknown>*& dstPointer, int& srcIndex);
        ALWAYS_INLINE void rewindBinaryOp();
        ALWAYS_INLINE void rewindUnaryOp();

        PassRefPtr<Label> emitComplexJumpScopes(Label* target, ControlFlowContext* topScope, ControlFlowContext* bottomScope);

        typedef HashMap<double, JSValue> NumberMap;
        typedef HashMap<StringImpl*, JSString*, IdentifierRepHash> IdentifierStringMap;
        
        RegisterID* emitCall(OpcodeID, RegisterID* dst, RegisterID* func, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);

        RegisterID* newRegister();

        // Adds a var slot and maps it to the name ident in symbolTable().
        RegisterID* addVar(const Identifier& ident, bool isConstant)
        {
            RegisterID* local;
            addVar(ident, isConstant, local);
            return local;
        }

        // Ditto. Returns true if a new RegisterID was added, false if a pre-existing RegisterID was re-used.
        bool addVar(const Identifier&, bool isConstant, RegisterID*&);
        
        // Adds an anonymous var slot. To give this slot a name, add it to symbolTable().
        RegisterID* addVar()
        {
            ++m_codeBlock->m_numVars;
            return newRegister();
        }

        // Returns the index of the added var.
        enum ConstantMode { IsConstant, IsVariable };
        enum FunctionMode { IsFunctionToSpecialize, NotFunctionOrNotSpecializable };
        int addGlobalVar(const Identifier&, ConstantMode, FunctionMode);

        void addParameter(const Identifier&, int parameterIndex);
        
        void preserveLastVar();
        bool shouldAvoidResolveGlobal();

        RegisterID& registerFor(int index)
        {
            if (index >= 0)
                return m_calleeRegisters[index];

            ASSERT(m_parameters.size());
            return m_parameters[index + m_parameters.size() + RegisterFile::CallFrameHeaderSize];
        }

        unsigned addConstant(const Identifier&);
        RegisterID* addConstantValue(JSValue);
        unsigned addRegExp(RegExp*);

        unsigned addConstantBuffer(unsigned length);
        
        FunctionExecutable* makeFunction(ExecState* exec, FunctionBodyNode* body)
        {
            return FunctionExecutable::create(exec, body->ident(), body->inferredName(), body->source(), body->usesArguments(), body->parameters(), body->isStrictMode(), body->lineNo(), body->lastLine());
        }

        FunctionExecutable* makeFunction(JSGlobalData* globalData, FunctionBodyNode* body)
        {
            return FunctionExecutable::create(*globalData, body->ident(), body->inferredName(), body->source(), body->usesArguments(), body->parameters(), body->isStrictMode(), body->lineNo(), body->lastLine());
        }

        JSString* addStringConstant(const Identifier&);

        void addLineInfo(unsigned lineNo)
        {
#if !ENABLE(OPCODE_SAMPLING)
            if (m_shouldEmitRichSourceInfo)
#endif
                m_codeBlock->addLineInfo(instructions().size(), lineNo);
        }

        RegisterID* emitInitLazyRegister(RegisterID*);

        Vector<Instruction>& instructions() { return m_instructions; }
        SymbolTable& symbolTable() { return *m_symbolTable; }

        bool shouldOptimizeLocals()
        {
            if (m_dynamicScopeDepth)
                return false;

            if (m_codeType != FunctionCode)
                return false;

            return true;
        }

        bool canOptimizeNonLocals()
        {
            if (m_dynamicScopeDepth)
                return false;

            if (m_codeType == EvalCode)
                return false;

            if (m_codeType == FunctionCode && m_codeBlock->usesEval())
                return false;

            return true;
        }

        RegisterID* emitThrowExpressionTooDeepException();

        void createArgumentsIfNecessary();
        void createActivationIfNecessary();
        RegisterID* createLazyRegisterIfNecessary(RegisterID*);
        
        Vector<Instruction> m_instructions;

        bool m_shouldEmitDebugHooks;
        bool m_shouldEmitProfileHooks;
        bool m_shouldEmitRichSourceInfo;

        Strong<ScopeChainNode> m_scopeChain;
        SymbolTable* m_symbolTable;

        ScopeNode* m_scopeNode;
        CodeBlock* m_codeBlock;

        // Some of these objects keep pointers to one another. They are arranged
        // to ensure a sane destruction order that avoids references to freed memory.
        HashSet<RefPtr<StringImpl>, IdentifierRepHash> m_functions;
        RegisterID m_ignoredResultRegister;
        RegisterID m_thisRegister;
        RegisterID* m_activationRegister;
        SegmentedVector<RegisterID, 32> m_constantPoolRegisters;
        SegmentedVector<RegisterID, 32> m_calleeRegisters;
        SegmentedVector<RegisterID, 32> m_parameters;
        SegmentedVector<Label, 32> m_labels;
        SegmentedVector<LabelScope, 8> m_labelScopes;
        RefPtr<RegisterID> m_lastVar;
        int m_finallyDepth;
        int m_dynamicScopeDepth;
        int m_baseScopeDepth;
        CodeType m_codeType;

        Vector<ControlFlowContext> m_scopeContextStack;
        Vector<SwitchInfo> m_switchContextStack;
        Vector<ForInContext> m_forInContextStack;

        int m_firstConstantIndex;
        int m_nextConstantOffset;
        unsigned m_globalConstantIndex;

        int m_globalVarStorageOffset;

        bool m_hasCreatedActivation;
        int m_firstLazyFunction;
        int m_lastLazyFunction;
        HashMap<unsigned int, FunctionBodyNode*, WTF::IntHash<unsigned int>, WTF::UnsignedWithZeroKeyHashTraits<unsigned int> > m_lazyFunctions;
        typedef HashMap<FunctionBodyNode*, unsigned> FunctionOffsetMap;
        FunctionOffsetMap m_functionOffsets;
        
        // Constant pool
        IdentifierMap m_identifierMap;
        JSValueMap m_jsValueMap;
        NumberMap m_numberMap;
        IdentifierStringMap m_stringMap;

        JSGlobalData* m_globalData;

        OpcodeID m_lastOpcodeID;
#ifndef NDEBUG
        size_t m_lastOpcodePosition;
#endif

        StackBounds m_stack;

        bool m_usesExceptions;
        bool m_expressionTooDeep;
    };

}

#endif // BytecodeGenerator_h