The Tor Browser: js/src/jit/MIR.h@6474c204b198 (annotated)

js/src/jit/MIR.h@6474c204b198 (annotated)

js/src/jit/MIR.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /*
  * Everything needed to build actual MIR instructions: the actual opcodes and
  * instructions, the instruction interface, and use chains.
  */
 #ifndef jit_MIR_h
 #define jit_MIR_h
 #include "mozilla/Array.h"
 #include "jsinfer.h"
 #include "jit/CompilerRoot.h"
 #include "jit/FixedList.h"
 #include "jit/InlineList.h"
 #include "jit/IonAllocPolicy.h"
 #include "jit/IonMacroAssembler.h"
 #include "jit/MOpcodes.h"
 #include "jit/TypeDescrSet.h"
 #include "jit/TypePolicy.h"
 #include "vm/ScopeObject.h"
 #include "vm/TypedArrayObject.h"
 namespace js {
 class StringObject;
 namespace jit {
 class BaselineInspector;
 class ValueNumberData;
 class Range;
 static const inline
 MIRType MIRTypeFromValue(const js::Value &vp)
 {
     if (vp.isDouble())
         return MIRType_Double;
     if (vp.isMagic()) {
         switch (vp.whyMagic()) {
           case JS_OPTIMIZED_ARGUMENTS:
             return MIRType_MagicOptimizedArguments;
           case JS_OPTIMIZED_OUT:
             return MIRType_MagicOptimizedOut;
           case JS_ELEMENTS_HOLE:
             return MIRType_MagicHole;
           case JS_IS_CONSTRUCTING:
             return MIRType_MagicIsConstructing;
           default:
             MOZ_ASSERT(!"Unexpected magic constant");
         }
     }
     return MIRTypeFromValueType(vp.extractNonDoubleType());
 }
 #define MIR_FLAG_LIST(_)                                                        \
     _(InWorklist)                                                               \
     _(EmittedAtUses)                                                            \
     _(LoopInvariant)                                                            \
     _(Commutative)                                                              \
     _(Movable)       /* Allow LICM and GVN to move this instruction */          \
     _(Lowered)       /* (Debug only) has a virtual register */                  \
     _(Guard)         /* Not removable if uses == 0 */                           \
                                                                                 \
     /* Keep the flagged instruction in resume points and do not substitute this
      * instruction by an UndefinedValue. This might be used by call inlining
      * when a function argument is not used by the inlined instructions.
      */                                                                         \
     _(ImplicitlyUsed)                                                           \
                                                                                 \
     /* The instruction has been marked dead for lazy removal from resume
      * points.
      */                                                                         \
     _(Unused)                                                                   \
     /* Marks if an instruction has fewer uses than the original code.
      * E.g. UCE can remove code.
      * Every instruction where an use is/was removed from an instruction and
      * as a result the number of operands doesn't equal the original code
      * need to get marked as UseRemoved. This is important for truncation
      * analysis to know, since if all original uses are still present,
      * it can ignore resumepoints.
      * Currently this is done for every pass after IonBuilder and before
      * Truncate Doubles. So every time removeUse is called, UseRemoved needs
      * to get set.
      */                                                                         \
     _(UseRemoved)
 class MDefinition;
 class MInstruction;
 class MBasicBlock;
 class MNode;
 class MUse;
 class MIRGraph;
 class MResumePoint;
 // Represents a use of a node.
 class MUse : public TempObject, public InlineListNode<MUse>
 {
     friend class MDefinition;
     MDefinition *producer_; // MDefinition that is being used.
     MNode *consumer_;       // The node that is using this operand.
     uint32_t index_;        // The index of this operand in its consumer.
     MUse(MDefinition *producer, MNode *consumer, uint32_t index)
       : producer_(producer),
         consumer_(consumer),
         index_(index)
     { }
   public:
     // Default constructor for use in vectors.
     MUse()
       : producer_(nullptr), consumer_(nullptr), index_(0)
     { }
     // Set data inside the MUse.
     void set(MDefinition *producer, MNode *consumer, uint32_t index) {
         producer_ = producer;
         consumer_ = consumer;
         index_ = index;
     }
     MDefinition *producer() const {
         JS_ASSERT(producer_ != nullptr);
         return producer_;
     }
     bool hasProducer() const {
         return producer_ != nullptr;
     }
     MNode *consumer() const {
         JS_ASSERT(consumer_ != nullptr);
         return consumer_;
     }
     uint32_t index() const {
         return index_;
     }
 };
 typedef InlineList<MUse>::iterator MUseIterator;
 // A node is an entry in the MIR graph. It has two kinds:
 //   MInstruction: an instruction which appears in the IR stream.
 //   MResumePoint: a list of instructions that correspond to the state of the
 //                 interpreter/Baseline stack.
 //
 // Nodes can hold references to MDefinitions. Each MDefinition has a list of
 // nodes holding such a reference (its use chain).
 class MNode : public TempObject
 {
     friend class MDefinition;
   protected:
     MBasicBlock *block_;    // Containing basic block.
   public:
     enum Kind {
         Definition,
         ResumePoint
     };
     MNode()
       : block_(nullptr)
     { }
     MNode(MBasicBlock *block)
       : block_(block)
     { }
     virtual Kind kind() const = 0;
     // Returns the definition at a given operand.
     virtual MDefinition *getOperand(size_t index) const = 0;
     virtual size_t numOperands() const = 0;
     bool isDefinition() const {
         return kind() == Definition;
     }
     bool isResumePoint() const {
         return kind() == ResumePoint;
     }
     MBasicBlock *block() const {
         return block_;
     }
     // Instructions needing to hook into type analysis should return a
     // TypePolicy.
     virtual TypePolicy *typePolicy() {
         return nullptr;
     }
     // Replaces an already-set operand during iteration over a use chain.
     MUseIterator replaceOperand(MUseIterator use, MDefinition *ins);
     // Replaces an already-set operand, updating use information.
     void replaceOperand(size_t index, MDefinition *ins);
     // Resets the operand to an uninitialized state, breaking the link
     // with the previous operand's producer.
     void discardOperand(size_t index);
     inline MDefinition *toDefinition();
     inline MResumePoint *toResumePoint();
   protected:
     // Sets an unset operand, updating use information.
     virtual void setOperand(size_t index, MDefinition *operand) = 0;
     // Gets the MUse corresponding to given operand.
     virtual MUse *getUseFor(size_t index) = 0;
 };
 class AliasSet {
   private:
     uint32_t flags_;
   public:
     enum Flag {
         None_             = 0,
         ObjectFields      = 1 << 0, // shape, class, slots, length etc.
         Element           = 1 << 1, // A member of obj->elements.
         DynamicSlot       = 1 << 2, // A member of obj->slots.
         FixedSlot         = 1 << 3, // A member of obj->fixedSlots().
         TypedArrayElement = 1 << 4, // A typed array element.
         DOMProperty       = 1 << 5, // A DOM property
         FrameArgument     = 1 << 6, // An argument kept on the stack frame
         AsmJSGlobalVar    = 1 << 7, // An asm.js global var
         AsmJSHeap         = 1 << 8, // An asm.js heap load
         TypedArrayLength  = 1 << 9,// A typed array's length
         Last              = TypedArrayLength,
         Any               = Last | (Last - 1),
         NumCategories     = 10,
         // Indicates load or store.
         Store_            = 1 << 31
     };
     static_assert((1 << NumCategories) - 1 == Any,
                   "NumCategories must include all flags present in Any");
     AliasSet(uint32_t flags)
       : flags_(flags)
     {
     }
   public:
     inline bool isNone() const {
         return flags_ == None_;
     }
     uint32_t flags() const {
         return flags_ & Any;
     }
     inline bool isStore() const {
         return !!(flags_ & Store_);
     }
     inline bool isLoad() const {
         return !isStore() && !isNone();
     }
     inline AliasSet operator |(const AliasSet &other) const {
         return AliasSet(flags_ | other.flags_);
     }
     inline AliasSet operator &(const AliasSet &other) const {
         return AliasSet(flags_ & other.flags_);
     }
     static AliasSet None() {
         return AliasSet(None_);
     }
     static AliasSet Load(uint32_t flags) {
         JS_ASSERT(flags && !(flags & Store_));
         return AliasSet(flags);
     }
     static AliasSet Store(uint32_t flags) {
         JS_ASSERT(flags && !(flags & Store_));
         return AliasSet(flags | Store_);
     }
 };
 // An MDefinition is an SSA name.
 class MDefinition : public MNode
 {
     friend class MBasicBlock;
   public:
     enum Opcode {
 #   define DEFINE_OPCODES(op) Op_##op,
         MIR_OPCODE_LIST(DEFINE_OPCODES)
 #   undef DEFINE_OPCODES
         Op_Invalid
     };
   private:
     InlineList<MUse> uses_;        // Use chain.
     uint32_t id_;                  // Instruction ID, which after block re-ordering
                                    // is sorted within a basic block.
     ValueNumberData *valueNumber_; // The instruction's value number (see GVN for details in use)
     Range *range_;                 // Any computed range for this def.
     MIRType resultType_;           // Representation of result type.
     types::TemporaryTypeSet *resultTypeSet_; // Optional refinement of the result type.
     uint32_t flags_;                 // Bit flags.
     union {
         MDefinition *dependency_;  // Implicit dependency (store, call, etc.) of this instruction.
                                    // Used by alias analysis, GVN and LICM.
         uint32_t virtualRegister_;   // Used by lowering to map definitions to virtual registers.
     };
     // Track bailouts by storing the current pc in MIR instruction. Also used
     // for profiling and keeping track of what the last known pc was.
     jsbytecode *trackedPc_;
   private:
     enum Flag {
         None = 0,
 #   define DEFINE_FLAG(flag) flag,
         MIR_FLAG_LIST(DEFINE_FLAG)
 #   undef DEFINE_FLAG
         Total
     };
     bool hasFlags(uint32_t flags) const {
         return (flags_ & flags) == flags;
     }
     void removeFlags(uint32_t flags) {
         flags_ &= ~flags;
     }
     void setFlags(uint32_t flags) {
         flags_ |= flags;
     }
   protected:
     virtual void setBlock(MBasicBlock *block) {
         block_ = block;
     }
   public:
     MDefinition()
       : id_(0),
         valueNumber_(nullptr),
         range_(nullptr),
         resultType_(MIRType_None),
         resultTypeSet_(nullptr),
         flags_(0),
         dependency_(nullptr),
         trackedPc_(nullptr)
     { }
     virtual Opcode op() const = 0;
     virtual const char *opName() const = 0;
     void printName(FILE *fp) const;
     static void PrintOpcodeName(FILE *fp, Opcode op);
     virtual void printOpcode(FILE *fp) const;
     void dump(FILE *fp) const;
     void dump() const;
     // For LICM.
     virtual bool neverHoist() const { return false; }
     // Also for LICM. Test whether this definition is likely to be a call, which
     // would clobber all or many of the floating-point registers, such that
     // hoisting floating-point constants out of containing loops isn't likely to
     // be worthwhile.
     virtual bool possiblyCalls() const { return false; }
     void setTrackedPc(jsbytecode *pc) {
         trackedPc_ = pc;
     }
     jsbytecode *trackedPc() {
         return trackedPc_;
     }
     // Return the range of this value, *before* any bailout checks. Contrast
     // this with the type() method, and the Range constructor which takes an
     // MDefinition*, which describe the value *after* any bailout checks.
     //
     // Warning: Range analysis is removing the bit-operations such as '| 0' at
     // the end of the transformations. Using this function to analyse any
     // operands after the truncate phase of the range analysis will lead to
     // errors. Instead, one should define the collectRangeInfoPreTrunc() to set
     // the right set of flags which are dependent on the range of the inputs.
     Range *range() const {
         JS_ASSERT(type() != MIRType_None);
         return range_;
     }
     void setRange(Range *range) {
         JS_ASSERT(type() != MIRType_None);
         range_ = range;
     }
     virtual HashNumber valueHash() const;
     virtual bool congruentTo(const MDefinition *ins) const {
         return false;
     }
     bool congruentIfOperandsEqual(const MDefinition *ins) const;
     virtual MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     virtual void analyzeEdgeCasesForward();
     virtual void analyzeEdgeCasesBackward();
     virtual bool truncate();
     virtual bool isOperandTruncated(size_t index) const;
     // Compute an absolute or symbolic range for the value of this node.
     virtual void computeRange(TempAllocator &alloc) {
     }
     // Collect information from the pre-truncated ranges.
     virtual void collectRangeInfoPreTrunc() {
     }
     MNode::Kind kind() const {
         return MNode::Definition;
     }
     uint32_t id() const {
         JS_ASSERT(block_);
         return id_;
     }
     void setId(uint32_t id) {
         id_ = id;
     }
     uint32_t valueNumber() const;
     void setValueNumber(uint32_t vn);
     ValueNumberData *valueNumberData() {
         return valueNumber_;
     }
     void clearValueNumberData() {
         valueNumber_ = nullptr;
     }
     void setValueNumberData(ValueNumberData *vn) {
         JS_ASSERT(valueNumber_ == nullptr);
         valueNumber_ = vn;
     }
 #define FLAG_ACCESSOR(flag) \
     bool is##flag() const {\
         return hasFlags(1 << flag);\
     }\
     void set##flag() {\
         JS_ASSERT(!hasFlags(1 << flag));\
         setFlags(1 << flag);\
     }\
     void setNot##flag() {\
         JS_ASSERT(hasFlags(1 << flag));\
         removeFlags(1 << flag);\
     }\
     void set##flag##Unchecked() {\
         setFlags(1 << flag);\
     }
     MIR_FLAG_LIST(FLAG_ACCESSOR)
 #undef FLAG_ACCESSOR
     // Return the type of this value. This may be speculative, and enforced
     // dynamically with the use of bailout checks. If all the bailout checks
     // pass, the value will have this type.
     //
     // Unless this is an MUrsh that has bailouts disabled, which, as a special
     // case, may return a value in (INT32_MAX,UINT32_MAX] even when its type()
     // is MIRType_Int32.
     MIRType type() const {
         return resultType_;
     }
     types::TemporaryTypeSet *resultTypeSet() const {
         return resultTypeSet_;
     }
     bool emptyResultTypeSet() const;
     bool mightBeType(MIRType type) const {
         MOZ_ASSERT(type != MIRType_Value);
         if (type == this->type())
             return true;
         if (MIRType_Value != this->type())
             return false;
         return !resultTypeSet() || resultTypeSet()->mightBeMIRType(type);
     }
     // Float32 specialization operations (see big comment in IonAnalysis before the Float32
     // specialization algorithm).
     virtual bool isFloat32Commutative() const { return false; }
     virtual bool canProduceFloat32() const { return false; }
     virtual bool canConsumeFloat32(MUse *use) const { return false; }
     virtual void trySpecializeFloat32(TempAllocator &alloc) {}
 #ifdef DEBUG
     // Used during the pass that checks that Float32 flow into valid MDefinitions
     virtual bool isConsistentFloat32Use(MUse *use) const {
         return type() == MIRType_Float32 || canConsumeFloat32(use);
     }
 #endif
     // Returns the beginning of this definition's use chain.
     MUseIterator usesBegin() const {
         return uses_.begin();
     }
     // Returns the end of this definition's use chain.
     MUseIterator usesEnd() const {
         return uses_.end();
     }
     bool canEmitAtUses() const {
         return !isEmittedAtUses();
     }
     // Removes a use at the given position
     MUseIterator removeUse(MUseIterator use);
     void removeUse(MUse *use) {
         uses_.remove(use);
     }
     // Number of uses of this instruction.
     size_t useCount() const;
     // Number of uses of this instruction.
     // (only counting MDefinitions, ignoring MResumePoints)
     size_t defUseCount() const;
     // Test whether this MDefinition has exactly one use.
     bool hasOneUse() const;
     // Test whether this MDefinition has exactly one use.
     // (only counting MDefinitions, ignoring MResumePoints)
     bool hasOneDefUse() const;
     // Test whether this MDefinition has at least one use.
     // (only counting MDefinitions, ignoring MResumePoints)
     bool hasDefUses() const;
     bool hasUses() const {
         return !uses_.empty();
     }
     virtual bool isControlInstruction() const {
         return false;
     }
     void addUse(MUse *use) {
         uses_.pushFront(use);
     }
     void replaceAllUsesWith(MDefinition *dom);
     // Mark this instruction as having replaced all uses of ins, as during GVN,
     // returning false if the replacement should not be performed. For use when
     // GVN eliminates instructions which are not equivalent to one another.
     virtual bool updateForReplacement(MDefinition *ins) {
         return true;
     }
     void setVirtualRegister(uint32_t vreg) {
         virtualRegister_ = vreg;
 #ifdef DEBUG
         setLoweredUnchecked();
 #endif
     }
     uint32_t virtualRegister() const {
         JS_ASSERT(isLowered());
         return virtualRegister_;
     }
   public:
     // Opcode testing and casts.
 #   define OPCODE_CASTS(opcode)                                             \
     bool is##opcode() const {                                               \
         return op() == Op_##opcode;                                         \
     }                                                                       \
     inline M##opcode *to##opcode();                                         \
     inline const M##opcode *to##opcode() const;
     MIR_OPCODE_LIST(OPCODE_CASTS)
 #   undef OPCODE_CASTS
     inline MInstruction *toInstruction();
     bool isInstruction() const {
         return !isPhi();
     }
     void setResultType(MIRType type) {
         resultType_ = type;
     }
     void setResultTypeSet(types::TemporaryTypeSet *types) {
         resultTypeSet_ = types;
     }
     MDefinition *dependency() const {
         return dependency_;
     }
     void setDependency(MDefinition *dependency) {
         dependency_ = dependency;
     }
     virtual AliasSet getAliasSet() const {
         // Instructions are effectful by default.
         return AliasSet::Store(AliasSet::Any);
     }
     bool isEffectful() const {
         return getAliasSet().isStore();
     }
     virtual bool mightAlias(const MDefinition *store) const {
         // Return whether this load may depend on the specified store, given
         // that the alias sets intersect. This may be refined to exclude
         // possible aliasing in cases where alias set flags are too imprecise.
         JS_ASSERT(!isEffectful() && store->isEffectful());
         JS_ASSERT(getAliasSet().flags() & store->getAliasSet().flags());
         return true;
     }
 };
 // An MUseDefIterator walks over uses in a definition, skipping any use that is
 // not a definition. Items from the use list must not be deleted during
 // iteration.
 class MUseDefIterator
 {
     MDefinition *def_;
     MUseIterator current_;
     MUseIterator search(MUseIterator start) {
         MUseIterator i(start);
         for (; i != def_->usesEnd(); i++) {
             if (i->consumer()->isDefinition())
                 return i;
         }
         return def_->usesEnd();
     }
   public:
     MUseDefIterator(MDefinition *def)
       : def_(def),
         current_(search(def->usesBegin()))
     { }
     operator bool() const {
         return current_ != def_->usesEnd();
     }
     MUseDefIterator operator ++(int) {
         MUseDefIterator old(*this);
         if (current_ != def_->usesEnd())
             current_++;
         current_ = search(current_);
         return old;
     }
     MUse *use() const {
         return *current_;
     }
     MDefinition *def() const {
         return current_->consumer()->toDefinition();
     }
     size_t index() const {
         return current_->index();
     }
 };
 // An instruction is an SSA name that is inserted into a basic block's IR
 // stream.
 class MInstruction
   : public MDefinition,
     public InlineListNode<MInstruction>
 {
     MResumePoint *resumePoint_;
   public:
     MInstruction()
       : resumePoint_(nullptr)
     { }
     virtual bool accept(MInstructionVisitor *visitor) = 0;
     void setResumePoint(MResumePoint *resumePoint) {
         JS_ASSERT(!resumePoint_);
         resumePoint_ = resumePoint;
     }
     MResumePoint *resumePoint() const {
         return resumePoint_;
     }
 };
 #define INSTRUCTION_HEADER(opcode)                                          \
     Opcode op() const {                                                     \
         return MDefinition::Op_##opcode;                                    \
     }                                                                       \
     const char *opName() const {                                            \
         return #opcode;                                                     \
     }                                                                       \
     bool accept(MInstructionVisitor *visitor) {                             \
         return visitor->visit##opcode(this);                                \
     }
 template <size_t Arity>
 class MAryInstruction : public MInstruction
 {
   protected:
     mozilla::Array<MUse, Arity> operands_;
     void setOperand(size_t index, MDefinition *operand) MOZ_FINAL MOZ_OVERRIDE {
         operands_[index].set(operand, this, index);
         operand->addUse(&operands_[index]);
     }
     MUse *getUseFor(size_t index) MOZ_FINAL MOZ_OVERRIDE {
         return &operands_[index];
     }
   public:
     MDefinition *getOperand(size_t index) const MOZ_FINAL MOZ_OVERRIDE {
         return operands_[index].producer();
     }
     size_t numOperands() const MOZ_FINAL MOZ_OVERRIDE {
         return Arity;
     }
 };
 class MNullaryInstruction : public MAryInstruction<0>
 { };
 class MUnaryInstruction : public MAryInstruction<1>
 {
   protected:
     MUnaryInstruction(MDefinition *ins)
     {
         setOperand(0, ins);
     }
   public:
     MDefinition *input() const {
         return getOperand(0);
     }
 };
 class MBinaryInstruction : public MAryInstruction<2>
 {
   protected:
     MBinaryInstruction(MDefinition *left, MDefinition *right)
     {
         setOperand(0, left);
         setOperand(1, right);
     }
   public:
     MDefinition *lhs() const {
         return getOperand(0);
     }
     MDefinition *rhs() const {
         return getOperand(1);
     }
   protected:
     HashNumber valueHash() const
     {
         MDefinition *lhs = getOperand(0);
         MDefinition *rhs = getOperand(1);
         return op() ^ lhs->valueNumber() ^ rhs->valueNumber();
     }
     void swapOperands() {
         MDefinition *temp = getOperand(0);
         replaceOperand(0, getOperand(1));
         replaceOperand(1, temp);
     }
     bool binaryCongruentTo(const MDefinition *ins) const
     {
         if (op() != ins->op())
             return false;
         if (type() != ins->type())
             return false;
         if (isEffectful() || ins->isEffectful())
             return false;
         const MDefinition *left = getOperand(0);
         const MDefinition *right = getOperand(1);
         const MDefinition *tmp;
         if (isCommutative() && left->valueNumber() > right->valueNumber()) {
             tmp = right;
             right = left;
             left = tmp;
         }
         const MBinaryInstruction *bi = static_cast<const MBinaryInstruction *>(ins);
         const MDefinition *insLeft = bi->getOperand(0);
         const MDefinition *insRight = bi->getOperand(1);
         if (isCommutative() && insLeft->valueNumber() > insRight->valueNumber()) {
             tmp = insRight;
             insRight = insLeft;
             insLeft = tmp;
         }
         return (left->valueNumber() == insLeft->valueNumber()) &&
                (right->valueNumber() == insRight->valueNumber());
     }
     // Return true if the operands to this instruction are both unsigned,
     // in which case any wrapping operands were replaced with the underlying
     // int32 operands.
     bool tryUseUnsignedOperands();
 };
 class MTernaryInstruction : public MAryInstruction<3>
 {
   protected:
     MTernaryInstruction(MDefinition *first, MDefinition *second, MDefinition *third)
     {
         setOperand(0, first);
         setOperand(1, second);
         setOperand(2, third);
     }
   protected:
     HashNumber valueHash() const
     {
         MDefinition *first = getOperand(0);
         MDefinition *second = getOperand(1);
         MDefinition *third = getOperand(2);
         return op() ^ first->valueNumber() ^ second->valueNumber() ^ third->valueNumber();
     }
 };
 class MQuaternaryInstruction : public MAryInstruction<4>
 {
   protected:
     MQuaternaryInstruction(MDefinition *first, MDefinition *second,
                            MDefinition *third, MDefinition *fourth)
     {
         setOperand(0, first);
         setOperand(1, second);
         setOperand(2, third);
         setOperand(3, fourth);
     }
   protected:
     HashNumber valueHash() const
     {
         MDefinition *first = getOperand(0);
         MDefinition *second = getOperand(1);
         MDefinition *third = getOperand(2);
         MDefinition *fourth = getOperand(3);
         return op() ^ first->valueNumber() ^ second->valueNumber() ^
                       third->valueNumber() ^ fourth->valueNumber();
     }
 };
 // Generates an LSnapshot without further effect.
 class MStart : public MNullaryInstruction
 {
   public:
     enum StartType {
         StartType_Default,
         StartType_Osr
     };
   private:
     StartType startType_;
   private:
     MStart(StartType startType)
       : startType_(startType)
     { }
   public:
     INSTRUCTION_HEADER(Start)
     static MStart *New(TempAllocator &alloc, StartType startType) {
         return new(alloc) MStart(startType);
     }
     StartType startType() {
         return startType_;
     }
 };
 // Instruction marking on entrypoint for on-stack replacement.
 // OSR may occur at loop headers (at JSOP_TRACE).
 // There is at most one MOsrEntry per MIRGraph.
 class MOsrEntry : public MNullaryInstruction
 {
   protected:
     MOsrEntry() {
         setResultType(MIRType_Pointer);
     }
   public:
     INSTRUCTION_HEADER(OsrEntry)
     static MOsrEntry *New(TempAllocator &alloc) {
         return new(alloc) MOsrEntry;
     }
 };
 // No-op instruction. This cannot be moved or eliminated, and is intended for
 // anchoring resume points at arbitrary points in a block.
 class MNop : public MNullaryInstruction
 {
   protected:
     MNop() {
     }
   public:
     INSTRUCTION_HEADER(Nop)
     static MNop *New(TempAllocator &alloc) {
         return new(alloc) MNop();
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // A constant js::Value.
 class MConstant : public MNullaryInstruction
 {
     Value value_;
   protected:
     MConstant(const Value &v, types::CompilerConstraintList *constraints);
   public:
     INSTRUCTION_HEADER(Constant)
     static MConstant *New(TempAllocator &alloc, const Value &v,
                           types::CompilerConstraintList *constraints = nullptr);
     static MConstant *NewAsmJS(TempAllocator &alloc, const Value &v, MIRType type);
     const js::Value &value() const {
         return value_;
     }
     const js::Value *vp() const {
         return &value_;
     }
     const bool valueToBoolean() const {
         // A hack to avoid this wordy pattern everywhere in the JIT.
         return ToBoolean(HandleValue::fromMarkedLocation(&value_));
     }
     void printOpcode(FILE *fp) const;
     HashNumber valueHash() const;
     bool congruentTo(const MDefinition *ins) const;
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool updateForReplacement(MDefinition *def) {
         MConstant *c = def->toConstant();
         // During constant folding, we don't want to replace a float32
         // value by a double value.
         if (type() == MIRType_Float32)
             return c->type() == MIRType_Float32;
         if (type() == MIRType_Double)
             return c->type() != MIRType_Float32;
         return true;
     }
     void computeRange(TempAllocator &alloc);
     bool truncate();
     bool canProduceFloat32() const;
 };
 // Deep clone a constant JSObject.
 class MCloneLiteral
   : public MUnaryInstruction,
     public ObjectPolicy<0>
 {
   protected:
     MCloneLiteral(MDefinition *obj)
       : MUnaryInstruction(obj)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(CloneLiteral)
     static MCloneLiteral *New(TempAllocator &alloc, MDefinition *obj);
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MParameter : public MNullaryInstruction
 {
     int32_t index_;
   public:
     static const int32_t THIS_SLOT = -1;
     MParameter(int32_t index, types::TemporaryTypeSet *types)
       : index_(index)
     {
         setResultType(MIRType_Value);
         setResultTypeSet(types);
     }
   public:
     INSTRUCTION_HEADER(Parameter)
     static MParameter *New(TempAllocator &alloc, int32_t index, types::TemporaryTypeSet *types);
     int32_t index() const {
         return index_;
     }
     void printOpcode(FILE *fp) const;
     HashNumber valueHash() const;
     bool congruentTo(const MDefinition *ins) const;
 };
 class MCallee : public MNullaryInstruction
 {
   public:
     MCallee()
     {
         setResultType(MIRType_Object);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Callee)
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     static MCallee *New(TempAllocator &alloc) {
         return new(alloc) MCallee();
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MControlInstruction : public MInstruction
 {
   public:
     MControlInstruction()
     { }
     virtual size_t numSuccessors() const = 0;
     virtual MBasicBlock *getSuccessor(size_t i) const = 0;
     virtual void replaceSuccessor(size_t i, MBasicBlock *successor) = 0;
     bool isControlInstruction() const {
         return true;
     }
     void printOpcode(FILE *fp) const;
 };
 class MTableSwitch MOZ_FINAL
   : public MControlInstruction,
     public NoFloatPolicy<0>
 {
     // The successors of the tableswitch
     // - First successor = the default case
     // - Successor 2 and higher = the cases sorted on case index.
     Vector<MBasicBlock*, 0, IonAllocPolicy> successors_;
     Vector<size_t, 0, IonAllocPolicy> cases_;
     // Contains the blocks/cases that still need to get build
     Vector<MBasicBlock*, 0, IonAllocPolicy> blocks_;
     MUse operand_;
     int32_t low_;
     int32_t high_;
     MTableSwitch(TempAllocator &alloc, MDefinition *ins,
                  int32_t low, int32_t high)
       : successors_(alloc),
         cases_(alloc),
         blocks_(alloc),
         low_(low),
         high_(high)
     {
         setOperand(0, ins);
     }
   protected:
     void setOperand(size_t index, MDefinition *operand) {
         JS_ASSERT(index == 0);
         operand_.set(operand, this, index);
         operand->addUse(&operand_);
     }
     MUse *getUseFor(size_t index) {
         JS_ASSERT(index == 0);
         return &operand_;
     }
   public:
     INSTRUCTION_HEADER(TableSwitch)
     static MTableSwitch *New(TempAllocator &alloc, MDefinition *ins, int32_t low, int32_t high);
     size_t numSuccessors() const {
         return successors_.length();
     }
     size_t addSuccessor(MBasicBlock *successor) {
         JS_ASSERT(successors_.length() < (size_t)(high_ - low_ + 2));
         JS_ASSERT(!successors_.empty());
         successors_.append(successor);
         return successors_.length() - 1;
     }
     MBasicBlock *getSuccessor(size_t i) const {
         JS_ASSERT(i < numSuccessors());
         return successors_[i];
     }
     void replaceSuccessor(size_t i, MBasicBlock *successor) {
         JS_ASSERT(i < numSuccessors());
         successors_[i] = successor;
     }
     MBasicBlock** blocks() {
         return &blocks_[0];
     }
     size_t numBlocks() const {
         return blocks_.length();
     }
     int32_t low() const {
         return low_;
     }
     int32_t high() const {
         return high_;
     }
     MBasicBlock *getDefault() const {
         return getSuccessor(0);
     }
     MBasicBlock *getCase(size_t i) const {
         return getSuccessor(cases_[i]);
     }
     size_t numCases() const {
         return high() - low() + 1;
     }
     size_t addDefault(MBasicBlock *block) {
         JS_ASSERT(successors_.empty());
         successors_.append(block);
         return 0;
     }
     void addCase(size_t successorIndex) {
         cases_.append(successorIndex);
     }
     MBasicBlock *getBlock(size_t i) const {
         JS_ASSERT(i < numBlocks());
         return blocks_[i];
     }
     void addBlock(MBasicBlock *block) {
         blocks_.append(block);
     }
     MDefinition *getOperand(size_t index) const {
         JS_ASSERT(index == 0);
         return operand_.producer();
     }
     size_t numOperands() const {
         return 1;
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 template <size_t Arity, size_t Successors>
 class MAryControlInstruction : public MControlInstruction
 {
     mozilla::Array<MUse, Arity> operands_;
     mozilla::Array<MBasicBlock *, Successors> successors_;
   protected:
     void setOperand(size_t index, MDefinition *operand) MOZ_FINAL MOZ_OVERRIDE {
         operands_[index].set(operand, this, index);
         operand->addUse(&operands_[index]);
     }
     void setSuccessor(size_t index, MBasicBlock *successor) {
         successors_[index] = successor;
     }
     MUse *getUseFor(size_t index) MOZ_FINAL MOZ_OVERRIDE {
         return &operands_[index];
     }
   public:
     MDefinition *getOperand(size_t index) const MOZ_FINAL MOZ_OVERRIDE {
         return operands_[index].producer();
     }
     size_t numOperands() const MOZ_FINAL MOZ_OVERRIDE {
         return Arity;
     }
     size_t numSuccessors() const MOZ_FINAL MOZ_OVERRIDE {
         return Successors;
     }
     MBasicBlock *getSuccessor(size_t i) const MOZ_FINAL MOZ_OVERRIDE {
         return successors_[i];
     }
     void replaceSuccessor(size_t i, MBasicBlock *succ) MOZ_FINAL MOZ_OVERRIDE {
         successors_[i] = succ;
     }
 };
 // Jump to the start of another basic block.
 class MGoto : public MAryControlInstruction<0, 1>
 {
     MGoto(MBasicBlock *target) {
         setSuccessor(0, target);
     }
   public:
     INSTRUCTION_HEADER(Goto)
     static MGoto *New(TempAllocator &alloc, MBasicBlock *target);
     MBasicBlock *target() {
         return getSuccessor(0);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 enum BranchDirection {
     FALSE_BRANCH,
     TRUE_BRANCH
 };
 static inline BranchDirection
 NegateBranchDirection(BranchDirection dir)
 {
     return (dir == FALSE_BRANCH) ? TRUE_BRANCH : FALSE_BRANCH;
 }
 // Tests if the input instruction evaluates to true or false, and jumps to the
 // start of a corresponding basic block.
 class MTest
   : public MAryControlInstruction<1, 2>,
     public TestPolicy
 {
     bool operandMightEmulateUndefined_;
     MTest(MDefinition *ins, MBasicBlock *if_true, MBasicBlock *if_false)
       : operandMightEmulateUndefined_(true)
     {
         setOperand(0, ins);
         setSuccessor(0, if_true);
         setSuccessor(1, if_false);
     }
   public:
     INSTRUCTION_HEADER(Test)
     static MTest *New(TempAllocator &alloc, MDefinition *ins,
                       MBasicBlock *ifTrue, MBasicBlock *ifFalse);
     MDefinition *input() const {
         return getOperand(0);
     }
     MBasicBlock *ifTrue() const {
         return getSuccessor(0);
     }
     MBasicBlock *ifFalse() const {
         return getSuccessor(1);
     }
     MBasicBlock *branchSuccessor(BranchDirection dir) const {
         return (dir == TRUE_BRANCH) ? ifTrue() : ifFalse();
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void infer();
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     void filtersUndefinedOrNull(bool trueBranch, MDefinition **subject, bool *filtersUndefined,
                                 bool *filtersNull);
     void markOperandCantEmulateUndefined() {
         operandMightEmulateUndefined_ = false;
     }
     bool operandMightEmulateUndefined() const {
         return operandMightEmulateUndefined_;
     }
 #ifdef DEBUG
     bool isConsistentFloat32Use(MUse *use) const {
         return true;
     }
 #endif
 };
 // Returns from this function to the previous caller.
 class MReturn
   : public MAryControlInstruction<1, 0>,
     public BoxInputsPolicy
 {
     MReturn(MDefinition *ins) {
         setOperand(0, ins);
     }
   public:
     INSTRUCTION_HEADER(Return)
     static MReturn *New(TempAllocator &alloc, MDefinition *ins) {
         return new(alloc) MReturn(ins);
     }
     MDefinition *input() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MThrow
   : public MAryControlInstruction<1, 0>,
     public BoxInputsPolicy
 {
     MThrow(MDefinition *ins) {
         setOperand(0, ins);
     }
   public:
     INSTRUCTION_HEADER(Throw)
     static MThrow *New(TempAllocator &alloc, MDefinition *ins) {
         return new(alloc) MThrow(ins);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     virtual AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Fabricate a type set containing only the type of the specified object.
 types::TemporaryTypeSet *
 MakeSingletonTypeSet(types::CompilerConstraintList *constraints, JSObject *obj);
 bool
 MergeTypes(MIRType *ptype, types::TemporaryTypeSet **ptypeSet,
            MIRType newType, types::TemporaryTypeSet *newTypeSet);
 class MNewArray : public MNullaryInstruction
 {
   public:
     enum AllocatingBehaviour {
         NewArray_Allocating,
         NewArray_Unallocating
     };
   private:
     // Number of space to allocate for the array.
     uint32_t count_;
     // Template for the created object.
     CompilerRootObject templateObject_;
     gc::InitialHeap initialHeap_;
     // Allocate space at initialization or not
     AllocatingBehaviour allocating_;
     MNewArray(types::CompilerConstraintList *constraints, uint32_t count, JSObject *templateObject,
               gc::InitialHeap initialHeap, AllocatingBehaviour allocating)
       : count_(count),
         templateObject_(templateObject),
         initialHeap_(initialHeap),
         allocating_(allocating)
     {
         setResultType(MIRType_Object);
         if (!templateObject->hasSingletonType())
             setResultTypeSet(MakeSingletonTypeSet(constraints, templateObject));
     }
   public:
     INSTRUCTION_HEADER(NewArray)
     static MNewArray *New(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                           uint32_t count, JSObject *templateObject,
                           gc::InitialHeap initialHeap, AllocatingBehaviour allocating)
     {
         return new(alloc) MNewArray(constraints, count, templateObject, initialHeap, allocating);
     }
     uint32_t count() const {
         return count_;
     }
     JSObject *templateObject() const {
         return templateObject_;
     }
     gc::InitialHeap initialHeap() const {
         return initialHeap_;
     }
     bool isAllocating() const {
         return allocating_ == NewArray_Allocating;
     }
     // Returns true if the code generator should call through to the
     // VM rather than the fast path.
     bool shouldUseVM() const;
     // NewArray is marked as non-effectful because all our allocations are
     // either lazy when we are using "new Array(length)" or bounded by the
     // script or the stack size when we are using "new Array(...)" or "[...]"
     // notations.  So we might have to allocate the array twice if we bail
     // during the computation of the first element of the square braket
     // notation.
     virtual AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MNewObject : public MNullaryInstruction
 {
     CompilerRootObject templateObject_;
     gc::InitialHeap initialHeap_;
     bool templateObjectIsClassPrototype_;
     MNewObject(types::CompilerConstraintList *constraints, JSObject *templateObject,
                gc::InitialHeap initialHeap, bool templateObjectIsClassPrototype)
       : templateObject_(templateObject),
         initialHeap_(initialHeap),
         templateObjectIsClassPrototype_(templateObjectIsClassPrototype)
     {
         JS_ASSERT_IF(templateObjectIsClassPrototype, !shouldUseVM());
         setResultType(MIRType_Object);
         if (!templateObject->hasSingletonType())
             setResultTypeSet(MakeSingletonTypeSet(constraints, templateObject));
     }
   public:
     INSTRUCTION_HEADER(NewObject)
     static MNewObject *New(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                            JSObject *templateObject, gc::InitialHeap initialHeap,
                            bool templateObjectIsClassPrototype)
     {
         return new(alloc) MNewObject(constraints, templateObject, initialHeap,
                                      templateObjectIsClassPrototype);
     }
     // Returns true if the code generator should call through to the
     // VM rather than the fast path.
     bool shouldUseVM() const;
     bool templateObjectIsClassPrototype() const {
         return templateObjectIsClassPrototype_;
     }
     JSObject *templateObject() const {
         return templateObject_;
     }
     gc::InitialHeap initialHeap() const {
         return initialHeap_;
     }
 };
 // Could be allocating either a new array or a new object.
 class MNewPar : public MUnaryInstruction
 {
     CompilerRootObject templateObject_;
     MNewPar(MDefinition *cx, JSObject *templateObject)
       : MUnaryInstruction(cx),
         templateObject_(templateObject)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(NewPar);
     static MNewPar *New(TempAllocator &alloc, MDefinition *cx, JSObject *templateObject) {
         return new(alloc) MNewPar(cx, templateObject);
     }
     MDefinition *forkJoinContext() const {
         return getOperand(0);
     }
     JSObject *templateObject() const {
         return templateObject_;
     }
 };
 // Creates a new derived type object. At runtime, this is just a call
 // to `BinaryBlock::createDerived()`. That is, the MIR itself does not
 // compile to particularly optimized code. However, using a distinct
 // MIR for creating derived type objects allows the compiler to
 // optimize ephemeral typed objects as would be created for a
 // reference like `a.b.c` -- here, the `a.b` will create an ephemeral
 // derived type object that aliases the memory of `a` itself. The
 // specific nature of `a.b` is revealed by using
 // `MNewDerivedTypedObject` rather than `MGetProperty` or what have
 // you. Moreover, the compiler knows that there are no side-effects,
 // so `MNewDerivedTypedObject` instructions can be reordered or pruned
 // as dead code.
 class MNewDerivedTypedObject
   : public MTernaryInstruction,
     public Mix3Policy<ObjectPolicy<0>,
                       ObjectPolicy<1>,
                       IntPolicy<2> >
 {
   private:
     TypeDescrSet set_;
     MNewDerivedTypedObject(TypeDescrSet set,
                            MDefinition *type,
                            MDefinition *owner,
                            MDefinition *offset)
       : MTernaryInstruction(type, owner, offset),
         set_(set)
     {
         setMovable();
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(NewDerivedTypedObject);
     static MNewDerivedTypedObject *New(TempAllocator &alloc, TypeDescrSet set,
                                        MDefinition *type, MDefinition *owner, MDefinition *offset)
     {
         return new(alloc) MNewDerivedTypedObject(set, type, owner, offset);
     }
     TypeDescrSet set() const {
         return set_;
     }
     MDefinition *type() const {
         return getOperand(0);
     }
     MDefinition *owner() const {
         return getOperand(1);
     }
     MDefinition *offset() const {
         return getOperand(2);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     virtual AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // Abort parallel execution.
 class MAbortPar : public MAryControlInstruction<0, 0>
 {
     MAbortPar()
       : MAryControlInstruction<0, 0>()
     {
         setResultType(MIRType_None);
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(AbortPar);
     static MAbortPar *New(TempAllocator &alloc) {
         return new(alloc) MAbortPar();
     }
 };
 // Setting __proto__ in an object literal.
 class MMutateProto
   : public MAryInstruction<2>,
     public MixPolicy<ObjectPolicy<0>, BoxPolicy<1> >
 {
   protected:
     MMutateProto(MDefinition *obj, MDefinition *value)
     {
         setOperand(0, obj);
         setOperand(1, value);
         setResultType(MIRType_None);
     }
   public:
     INSTRUCTION_HEADER(MutateProto)
     static MMutateProto *New(TempAllocator &alloc, MDefinition *obj, MDefinition *value)
     {
         return new(alloc) MMutateProto(obj, value);
     }
     MDefinition *getObject() const {
         return getOperand(0);
     }
     MDefinition *getValue() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Slow path for adding a property to an object without a known base.
 class MInitProp
   : public MAryInstruction<2>,
     public MixPolicy<ObjectPolicy<0>, BoxPolicy<1> >
 {
   public:
     CompilerRootPropertyName name_;
   protected:
     MInitProp(MDefinition *obj, PropertyName *name, MDefinition *value)
       : name_(name)
     {
         setOperand(0, obj);
         setOperand(1, value);
         setResultType(MIRType_None);
     }
   public:
     INSTRUCTION_HEADER(InitProp)
     static MInitProp *New(TempAllocator &alloc, MDefinition *obj, PropertyName *name,
                           MDefinition *value)
     {
         return new(alloc) MInitProp(obj, name, value);
     }
     MDefinition *getObject() const {
         return getOperand(0);
     }
     MDefinition *getValue() const {
         return getOperand(1);
     }
     PropertyName *propertyName() const {
         return name_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MInitPropGetterSetter
   : public MBinaryInstruction,
     public MixPolicy<ObjectPolicy<0>, ObjectPolicy<1> >
 {
     CompilerRootPropertyName name_;
     MInitPropGetterSetter(MDefinition *obj, PropertyName *name, MDefinition *value)
       : MBinaryInstruction(obj, value),
         name_(name)
     { }
   public:
     INSTRUCTION_HEADER(InitPropGetterSetter)
     static MInitPropGetterSetter *New(TempAllocator &alloc, MDefinition *obj, PropertyName *name,
                                       MDefinition *value)
     {
         return new(alloc) MInitPropGetterSetter(obj, name, value);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *value() const {
         return getOperand(1);
     }
     PropertyName *name() const {
         return name_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MInitElem
   : public MAryInstruction<3>,
     public Mix3Policy<ObjectPolicy<0>, BoxPolicy<1>, BoxPolicy<2> >
 {
     MInitElem(MDefinition *obj, MDefinition *id, MDefinition *value)
     {
         setOperand(0, obj);
         setOperand(1, id);
         setOperand(2, value);
         setResultType(MIRType_None);
     }
   public:
     INSTRUCTION_HEADER(InitElem)
     static MInitElem *New(TempAllocator &alloc, MDefinition *obj, MDefinition *id,
                           MDefinition *value)
     {
         return new(alloc) MInitElem(obj, id, value);
     }
     MDefinition *getObject() const {
         return getOperand(0);
     }
     MDefinition *getId() const {
         return getOperand(1);
     }
     MDefinition *getValue() const {
         return getOperand(2);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MInitElemGetterSetter
   : public MTernaryInstruction,
     public Mix3Policy<ObjectPolicy<0>, BoxPolicy<1>, ObjectPolicy<2> >
 {
     MInitElemGetterSetter(MDefinition *obj, MDefinition *id, MDefinition *value)
       : MTernaryInstruction(obj, id, value)
     { }
   public:
     INSTRUCTION_HEADER(InitElemGetterSetter)
     static MInitElemGetterSetter *New(TempAllocator &alloc, MDefinition *obj, MDefinition *id,
                                       MDefinition *value)
     {
         return new(alloc) MInitElemGetterSetter(obj, id, value);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *idValue() const {
         return getOperand(1);
     }
     MDefinition *value() const {
         return getOperand(2);
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MVariadicInstruction : public MInstruction
 {
     FixedList<MUse> operands_;
   protected:
     bool init(TempAllocator &alloc, size_t length) {
         return operands_.init(alloc, length);
     }
   public:
     // Will assert if called before initialization.
     MDefinition *getOperand(size_t index) const MOZ_FINAL MOZ_OVERRIDE {
         return operands_[index].producer();
     }
     size_t numOperands() const MOZ_FINAL MOZ_OVERRIDE {
         return operands_.length();
     }
     void setOperand(size_t index, MDefinition *operand) MOZ_FINAL MOZ_OVERRIDE {
         operands_[index].set(operand, this, index);
         operand->addUse(&operands_[index]);
     }
     MUse *getUseFor(size_t index) MOZ_FINAL MOZ_OVERRIDE {
         return &operands_[index];
     }
 };
 class MCall
   : public MVariadicInstruction,
     public CallPolicy
 {
   private:
     // An MCall uses the MPrepareCall, MDefinition for the function, and
     // MPassArg instructions. They are stored in the same list.
     static const size_t FunctionOperandIndex   = 0;
     static const size_t NumNonArgumentOperands = 1;
   protected:
     // True if the call is for JSOP_NEW.
     bool construct_;
     // Monomorphic cache of single target from TI, or nullptr.
     CompilerRootFunction target_;
     // Original value of argc from the bytecode.
     uint32_t numActualArgs_;
     bool needsArgCheck_;
     MCall(JSFunction *target, uint32_t numActualArgs, bool construct)
       : construct_(construct),
         target_(target),
         numActualArgs_(numActualArgs),
         needsArgCheck_(true)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(Call)
     static MCall *New(TempAllocator &alloc, JSFunction *target, size_t maxArgc, size_t numActualArgs,
                       bool construct, bool isDOMCall);
     void initFunction(MDefinition *func) {
         return setOperand(FunctionOperandIndex, func);
     }
     bool needsArgCheck() const {
         return needsArgCheck_;
     }
     void disableArgCheck() {
         needsArgCheck_ = false;
     }
     MDefinition *getFunction() const {
         return getOperand(FunctionOperandIndex);
     }
     void replaceFunction(MInstruction *newfunc) {
         replaceOperand(FunctionOperandIndex, newfunc);
     }
     void addArg(size_t argnum, MDefinition *arg);
     MDefinition *getArg(uint32_t index) const {
         return getOperand(NumNonArgumentOperands + index);
     }
     static size_t IndexOfThis() {
         return NumNonArgumentOperands;
     }
     static size_t IndexOfArgument(size_t index) {
         return NumNonArgumentOperands + index + 1; // +1 to skip |this|.
     }
     static size_t IndexOfStackArg(size_t index) {
         return NumNonArgumentOperands + index;
     }
     // For TI-informed monomorphic callsites.
     JSFunction *getSingleTarget() const {
         return target_;
     }
     bool isConstructing() const {
         return construct_;
     }
     // The number of stack arguments is the max between the number of formal
     // arguments and the number of actual arguments. The number of stack
     // argument includes the |undefined| padding added in case of underflow.
     // Includes |this|.
     uint32_t numStackArgs() const {
         return numOperands() - NumNonArgumentOperands;
     }
     // Does not include |this|.
     uint32_t numActualArgs() const {
         return numActualArgs_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
     virtual bool isCallDOMNative() const {
         return false;
     }
     // A method that can be called to tell the MCall to figure out whether it's
     // movable or not.  This can't be done in the constructor, because it
     // depends on the arguments to the call, and those aren't passed to the
     // constructor but are set up later via addArg.
     virtual void computeMovable() {
     }
 };
 class MCallDOMNative : public MCall
 {
     // A helper class for MCalls for DOM natives.  Note that this is NOT
     // actually a separate MIR op from MCall, because all sorts of places use
     // isCall() to check for calls and all we really want is to overload a few
     // virtual things from MCall.
   protected:
     MCallDOMNative(JSFunction *target, uint32_t numActualArgs)
         : MCall(target, numActualArgs, false)
     {
         // If our jitinfo is not marked movable, that means that our C++
         // implementation is fallible or that we have no hope of ever doing the
         // sort of argument analysis that would allow us to detemine that we're
         // side-effect-free.  In the latter case we wouldn't get DCEd no matter
         // what, but for the former case we have to explicitly say that we can't
         // be DCEd.
         if (!getJitInfo()->isMovable)
             setGuard();
     }
     friend MCall *MCall::New(TempAllocator &alloc, JSFunction *target, size_t maxArgc,
                              size_t numActualArgs, bool construct, bool isDOMCall);
     const JSJitInfo *getJitInfo() const;
   public:
     virtual AliasSet getAliasSet() const MOZ_OVERRIDE;
     virtual bool congruentTo(const MDefinition *ins) const MOZ_OVERRIDE;
     virtual bool isCallDOMNative() const MOZ_OVERRIDE {
         return true;
     }
     virtual void computeMovable() MOZ_OVERRIDE;
 };
 // arr.splice(start, deleteCount) with unused return value.
 class MArraySplice
   : public MTernaryInstruction,
     public Mix3Policy<ObjectPolicy<0>, IntPolicy<1>, IntPolicy<2> >
 {
   private:
     MArraySplice(MDefinition *object, MDefinition *start, MDefinition *deleteCount)
       : MTernaryInstruction(object, start, deleteCount)
     { }
   public:
     INSTRUCTION_HEADER(ArraySplice)
     static MArraySplice *New(TempAllocator &alloc, MDefinition *object,
                              MDefinition *start, MDefinition *deleteCount)
     {
         return new(alloc) MArraySplice(object, start, deleteCount);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *start() const {
         return getOperand(1);
     }
     MDefinition *deleteCount() const {
         return getOperand(2);
     }
     bool possiblyCalls() const {
         return true;
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 // fun.apply(self, arguments)
 class MApplyArgs
   : public MAryInstruction<3>,
     public MixPolicy<ObjectPolicy<0>, MixPolicy<IntPolicy<1>, BoxPolicy<2> > >
 {
   protected:
     // Monomorphic cache of single target from TI, or nullptr.
     CompilerRootFunction target_;
     MApplyArgs(JSFunction *target, MDefinition *fun, MDefinition *argc, MDefinition *self)
       : target_(target)
     {
         setOperand(0, fun);
         setOperand(1, argc);
         setOperand(2, self);
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(ApplyArgs)
     static MApplyArgs *New(TempAllocator &alloc, JSFunction *target, MDefinition *fun,
                            MDefinition *argc, MDefinition *self);
     MDefinition *getFunction() const {
         return getOperand(0);
     }
     // For TI-informed monomorphic callsites.
     JSFunction *getSingleTarget() const {
         return target_;
     }
     MDefinition *getArgc() const {
         return getOperand(1);
     }
     MDefinition *getThis() const {
         return getOperand(2);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MBail : public MNullaryInstruction
 {
   protected:
     MBail()
     {
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(Bail)
     static MBail *
     New(TempAllocator &alloc) {
         return new(alloc) MBail();
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MAssertFloat32 : public MUnaryInstruction
 {
   protected:
     bool mustBeFloat32_;
     MAssertFloat32(MDefinition *value, bool mustBeFloat32)
       : MUnaryInstruction(value), mustBeFloat32_(mustBeFloat32)
     {
     }
   public:
     INSTRUCTION_HEADER(AssertFloat32)
     static MAssertFloat32 *New(TempAllocator &alloc, MDefinition *value, bool mustBeFloat32) {
         return new(alloc) MAssertFloat32(value, mustBeFloat32);
     }
     bool canConsumeFloat32(MUse *use) const { return true; }
     bool mustBeFloat32() const { return mustBeFloat32_; }
 };
 class MGetDynamicName
   : public MAryInstruction<2>,
     public MixPolicy<ObjectPolicy<0>, ConvertToStringPolicy<1> >
 {
   protected:
     MGetDynamicName(MDefinition *scopeChain, MDefinition *name)
     {
         setOperand(0, scopeChain);
         setOperand(1, name);
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(GetDynamicName)
     static MGetDynamicName *
     New(TempAllocator &alloc, MDefinition *scopeChain, MDefinition *name) {
         return new(alloc) MGetDynamicName(scopeChain, name);
     }
     MDefinition *getScopeChain() const {
         return getOperand(0);
     }
     MDefinition *getName() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Bailout if the input string contains 'arguments' or 'eval'.
 class MFilterArgumentsOrEval
   : public MAryInstruction<1>,
     public BoxExceptPolicy<0, MIRType_String>
 {
   protected:
     MFilterArgumentsOrEval(MDefinition *string)
     {
         setOperand(0, string);
         setGuard();
         setResultType(MIRType_None);
     }
   public:
     INSTRUCTION_HEADER(FilterArgumentsOrEval)
     static MFilterArgumentsOrEval *New(TempAllocator &alloc, MDefinition *string) {
         return new(alloc) MFilterArgumentsOrEval(string);
     }
     MDefinition *getString() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MCallDirectEval
   : public MAryInstruction<3>,
     public MixPolicy<ObjectPolicy<0>,
                      MixPolicy<BoxExceptPolicy<1, MIRType_String>, BoxPolicy<2> > >
 {
   protected:
     MCallDirectEval(MDefinition *scopeChain, MDefinition *string, MDefinition *thisValue,
                     jsbytecode *pc)
         : pc_(pc)
     {
         setOperand(0, scopeChain);
         setOperand(1, string);
         setOperand(2, thisValue);
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(CallDirectEval)
     static MCallDirectEval *
     New(TempAllocator &alloc, MDefinition *scopeChain, MDefinition *string, MDefinition *thisValue,
         jsbytecode *pc)
     {
         return new(alloc) MCallDirectEval(scopeChain, string, thisValue, pc);
     }
     MDefinition *getScopeChain() const {
         return getOperand(0);
     }
     MDefinition *getString() const {
         return getOperand(1);
     }
     MDefinition *getThisValue() const {
         return getOperand(2);
     }
     jsbytecode  *pc() const {
         return pc_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
   private:
     jsbytecode *pc_;
 };
 class MCompare
   : public MBinaryInstruction,
     public ComparePolicy
 {
   public:
     enum CompareType {
         // Anything compared to Undefined
         Compare_Undefined,
         // Anything compared to Null
         Compare_Null,
         // Undefined compared to Boolean
         // Null      compared to Boolean
         // Double    compared to Boolean
         // String    compared to Boolean
         // Object    compared to Boolean
         // Value     compared to Boolean
         Compare_Boolean,
         // Int32   compared to Int32
         // Boolean compared to Boolean
         Compare_Int32,
         Compare_Int32MaybeCoerceBoth,
         Compare_Int32MaybeCoerceLHS,
         Compare_Int32MaybeCoerceRHS,
         // Int32 compared as unsigneds
         Compare_UInt32,
         // Double compared to Double
         Compare_Double,
         Compare_DoubleMaybeCoerceLHS,
         Compare_DoubleMaybeCoerceRHS,
         // Float compared to Float
         Compare_Float32,
         // String compared to String
         Compare_String,
         // Undefined compared to String
         // Null      compared to String
         // Boolean   compared to String
         // Int32     compared to String
         // Double    compared to String
         // Object    compared to String
         // Value     compared to String
         Compare_StrictString,
         // Object compared to Object
         Compare_Object,
         // Compare 2 values bitwise
         Compare_Value,
         // All other possible compares
         Compare_Unknown
     };
   private:
     CompareType compareType_;
     JSOp jsop_;
     bool operandMightEmulateUndefined_;
     bool operandsAreNeverNaN_;
     // When a floating-point comparison is converted to an integer comparison
     // (when range analysis proves it safe), we need to convert the operands
     // to integer as well.
     bool truncateOperands_;
     MCompare(MDefinition *left, MDefinition *right, JSOp jsop)
       : MBinaryInstruction(left, right),
         compareType_(Compare_Unknown),
         jsop_(jsop),
         operandMightEmulateUndefined_(true),
         operandsAreNeverNaN_(false),
         truncateOperands_(false)
     {
         setResultType(MIRType_Boolean);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Compare)
     static MCompare *New(TempAllocator &alloc, MDefinition *left, MDefinition *right, JSOp op);
     static MCompare *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right, JSOp op,
                               CompareType compareType);
     bool tryFold(bool *result);
     bool evaluateConstantOperands(bool *result);
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     void filtersUndefinedOrNull(bool trueBranch, MDefinition **subject, bool *filtersUndefined,
                                 bool *filtersNull);
     void infer(BaselineInspector *inspector, jsbytecode *pc);
     CompareType compareType() const {
         return compareType_;
     }
     bool isInt32Comparison() const {
         return compareType() == Compare_Int32 ||
                compareType() == Compare_Int32MaybeCoerceBoth ||
                compareType() == Compare_Int32MaybeCoerceLHS ||
                compareType() == Compare_Int32MaybeCoerceRHS;
     }
     bool isDoubleComparison() const {
         return compareType() == Compare_Double ||
                compareType() == Compare_DoubleMaybeCoerceLHS ||
                compareType() == Compare_DoubleMaybeCoerceRHS;
     }
     bool isFloat32Comparison() const {
         return compareType() == Compare_Float32;
     }
     void setCompareType(CompareType type) {
         compareType_ = type;
     }
     MIRType inputType();
     JSOp jsop() const {
         return jsop_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     void markNoOperandEmulatesUndefined() {
         operandMightEmulateUndefined_ = false;
     }
     bool operandMightEmulateUndefined() const {
         return operandMightEmulateUndefined_;
     }
     bool operandsAreNeverNaN() const {
         return operandsAreNeverNaN_;
     }
     AliasSet getAliasSet() const {
         // Strict equality is never effectful.
         if (jsop_ == JSOP_STRICTEQ || jsop_ == JSOP_STRICTNE)
             return AliasSet::None();
         if (compareType_ == Compare_Unknown)
             return AliasSet::Store(AliasSet::Any);
         JS_ASSERT(compareType_ <= Compare_Value);
         return AliasSet::None();
     }
     void printOpcode(FILE *fp) const;
     void collectRangeInfoPreTrunc();
     void trySpecializeFloat32(TempAllocator &alloc);
     bool isFloat32Commutative() const { return true; }
     bool truncate();
     bool isOperandTruncated(size_t index) const;
 # ifdef DEBUG
     bool isConsistentFloat32Use(MUse *use) const {
         // Both sides of the compare can be Float32
         return compareType_ == Compare_Float32;
     }
 # endif
   protected:
     bool congruentTo(const MDefinition *ins) const {
         if (!binaryCongruentTo(ins))
             return false;
         return compareType() == ins->toCompare()->compareType() &&
                jsop() == ins->toCompare()->jsop();
     }
 };
 // Takes a typed value and returns an untyped value.
 class MBox : public MUnaryInstruction
 {
     MBox(TempAllocator &alloc, MDefinition *ins)
       : MUnaryInstruction(ins)
     {
         setResultType(MIRType_Value);
         if (ins->resultTypeSet()) {
             setResultTypeSet(ins->resultTypeSet());
         } else if (ins->type() != MIRType_Value) {
             types::Type ntype = ins->type() == MIRType_Object
                                 ? types::Type::AnyObjectType()
                                 : types::Type::PrimitiveType(ValueTypeFromMIRType(ins->type()));
             setResultTypeSet(alloc.lifoAlloc()->new_<types::TemporaryTypeSet>(ntype));
         }
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Box)
     static MBox *New(TempAllocator &alloc, MDefinition *ins)
     {
         // Cannot box a box.
         JS_ASSERT(ins->type() != MIRType_Value);
         return new(alloc) MBox(alloc, ins);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // Note: the op may have been inverted during lowering (to put constants in a
 // position where they can be immediates), so it is important to use the
 // lir->jsop() instead of the mir->jsop() when it is present.
 static inline Assembler::Condition
 JSOpToCondition(MCompare::CompareType compareType, JSOp op)
 {
     bool isSigned = (compareType != MCompare::Compare_UInt32);
     return JSOpToCondition(op, isSigned);
 }
 // Takes a typed value and checks if it is a certain type. If so, the payload
 // is unpacked and returned as that type. Otherwise, it is considered a
 // deoptimization.
 class MUnbox : public MUnaryInstruction, public BoxInputsPolicy
 {
   public:
     enum Mode {
         Fallible,       // Check the type, and deoptimize if unexpected.
         Infallible,     // Type guard is not necessary.
         TypeBarrier     // Guard on the type, and act like a TypeBarrier on failure.
     };
   private:
     Mode mode_;
     BailoutKind bailoutKind_;
     MUnbox(MDefinition *ins, MIRType type, Mode mode, BailoutKind kind)
       : MUnaryInstruction(ins),
         mode_(mode)
     {
         JS_ASSERT(ins->type() == MIRType_Value);
         JS_ASSERT(type == MIRType_Boolean ||
                   type == MIRType_Int32   ||
                   type == MIRType_Double  ||
                   type == MIRType_String  ||
                   type == MIRType_Object);
         setResultType(type);
         setResultTypeSet(ins->resultTypeSet());
         setMovable();
         if (mode_ == TypeBarrier || mode_ == Fallible)
             setGuard();
         bailoutKind_ = kind;
     }
   public:
     INSTRUCTION_HEADER(Unbox)
     static MUnbox *New(TempAllocator &alloc, MDefinition *ins, MIRType type, Mode mode)
     {
         return new(alloc) MUnbox(ins, type, mode, Bailout_Normal);
     }
     static MUnbox *New(TempAllocator &alloc, MDefinition *ins, MIRType type, Mode mode,
                        BailoutKind kind)
     {
         return new(alloc) MUnbox(ins, type, mode, kind);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     Mode mode() const {
         return mode_;
     }
     BailoutKind bailoutKind() const {
         // If infallible, no bailout should be generated.
         JS_ASSERT(fallible());
         return bailoutKind_;
     }
     bool fallible() const {
         return mode() != Infallible;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isUnbox() || ins->toUnbox()->mode() != mode())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void printOpcode(FILE *fp) const;
     void makeInfallible() {
         // Should only be called if we're already Infallible or TypeBarrier
         JS_ASSERT(mode() != Fallible);
         mode_ = Infallible;
     }
 };
 class MGuardObject : public MUnaryInstruction, public SingleObjectPolicy
 {
     MGuardObject(MDefinition *ins)
       : MUnaryInstruction(ins)
     {
         setGuard();
         setMovable();
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(GuardObject)
     static MGuardObject *New(TempAllocator &alloc, MDefinition *ins) {
         return new(alloc) MGuardObject(ins);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MGuardString
   : public MUnaryInstruction,
     public StringPolicy<0>
 {
     MGuardString(MDefinition *ins)
       : MUnaryInstruction(ins)
     {
         setGuard();
         setMovable();
         setResultType(MIRType_String);
     }
   public:
     INSTRUCTION_HEADER(GuardString)
     static MGuardString *New(TempAllocator &alloc, MDefinition *ins) {
         return new(alloc) MGuardString(ins);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MAssertRange
   : public MUnaryInstruction
 {
     // This is the range checked by the assertion. Don't confuse this with the
     // range_ member or the range() accessor. Since MAssertRange doesn't return
     // a value, it doesn't use those.
     const Range *assertedRange_;
     MAssertRange(MDefinition *ins, const Range *assertedRange)
       : MUnaryInstruction(ins), assertedRange_(assertedRange)
     {
         setGuard();
         setMovable();
         setResultType(MIRType_None);
     }
   public:
     INSTRUCTION_HEADER(AssertRange)
     static MAssertRange *New(TempAllocator &alloc, MDefinition *ins, const Range *assertedRange) {
         return new(alloc) MAssertRange(ins, assertedRange);
     }
     const Range *assertedRange() const {
         return assertedRange_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void printOpcode(FILE *fp) const;
 };
 // Caller-side allocation of |this| for |new|:
 // Given a templateobject, construct |this| for JSOP_NEW
 class MCreateThisWithTemplate
   : public MNullaryInstruction
 {
     // Template for |this|, provided by TI
     CompilerRootObject templateObject_;
     gc::InitialHeap initialHeap_;
     MCreateThisWithTemplate(types::CompilerConstraintList *constraints, JSObject *templateObject,
                             gc::InitialHeap initialHeap)
       : templateObject_(templateObject),
         initialHeap_(initialHeap)
     {
         setResultType(MIRType_Object);
         setResultTypeSet(MakeSingletonTypeSet(constraints, templateObject));
     }
   public:
     INSTRUCTION_HEADER(CreateThisWithTemplate);
     static MCreateThisWithTemplate *New(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                                         JSObject *templateObject, gc::InitialHeap initialHeap)
     {
         return new(alloc) MCreateThisWithTemplate(constraints, templateObject, initialHeap);
     }
     JSObject *templateObject() const {
         return templateObject_;
     }
     gc::InitialHeap initialHeap() const {
         return initialHeap_;
     }
     // Although creation of |this| modifies global state, it is safely repeatable.
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // Caller-side allocation of |this| for |new|:
 // Given a prototype operand, construct |this| for JSOP_NEW.
 class MCreateThisWithProto
   : public MBinaryInstruction,
     public MixPolicy<ObjectPolicy<0>, ObjectPolicy<1> >
 {
     MCreateThisWithProto(MDefinition *callee, MDefinition *prototype)
       : MBinaryInstruction(callee, prototype)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(CreateThisWithProto)
     static MCreateThisWithProto *New(TempAllocator &alloc, MDefinition *callee,
                                      MDefinition *prototype)
     {
         return new(alloc) MCreateThisWithProto(callee, prototype);
     }
     MDefinition *getCallee() const {
         return getOperand(0);
     }
     MDefinition *getPrototype() const {
         return getOperand(1);
     }
     // Although creation of |this| modifies global state, it is safely repeatable.
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Caller-side allocation of |this| for |new|:
 // Constructs |this| when possible, else MagicValue(JS_IS_CONSTRUCTING).
 class MCreateThis
   : public MUnaryInstruction,
     public ObjectPolicy<0>
 {
     MCreateThis(MDefinition *callee)
       : MUnaryInstruction(callee)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(CreateThis)
     static MCreateThis *New(TempAllocator &alloc, MDefinition *callee)
     {
         return new(alloc) MCreateThis(callee);
     }
     MDefinition *getCallee() const {
         return getOperand(0);
     }
     // Although creation of |this| modifies global state, it is safely repeatable.
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Eager initialization of arguments object.
 class MCreateArgumentsObject
   : public MUnaryInstruction,
     public ObjectPolicy<0>
 {
     MCreateArgumentsObject(MDefinition *callObj)
       : MUnaryInstruction(callObj)
     {
         setResultType(MIRType_Object);
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(CreateArgumentsObject)
     static MCreateArgumentsObject *New(TempAllocator &alloc, MDefinition *callObj) {
         return new(alloc) MCreateArgumentsObject(callObj);
     }
     MDefinition *getCallObject() const {
         return getOperand(0);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MGetArgumentsObjectArg
   : public MUnaryInstruction,
     public ObjectPolicy<0>
 {
     size_t argno_;
     MGetArgumentsObjectArg(MDefinition *argsObject, size_t argno)
       : MUnaryInstruction(argsObject),
         argno_(argno)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(GetArgumentsObjectArg)
     static MGetArgumentsObjectArg *New(TempAllocator &alloc, MDefinition *argsObj, size_t argno)
     {
         return new(alloc) MGetArgumentsObjectArg(argsObj, argno);
     }
     MDefinition *getArgsObject() const {
         return getOperand(0);
     }
     size_t argno() const {
         return argno_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::Any);
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MSetArgumentsObjectArg
   : public MBinaryInstruction,
     public MixPolicy<ObjectPolicy<0>, BoxPolicy<1> >
 {
     size_t argno_;
     MSetArgumentsObjectArg(MDefinition *argsObj, size_t argno, MDefinition *value)
       : MBinaryInstruction(argsObj, value),
         argno_(argno)
     {
     }
   public:
     INSTRUCTION_HEADER(SetArgumentsObjectArg)
     static MSetArgumentsObjectArg *New(TempAllocator &alloc, MDefinition *argsObj, size_t argno,
                                        MDefinition *value)
     {
         return new(alloc) MSetArgumentsObjectArg(argsObj, argno, value);
     }
     MDefinition *getArgsObject() const {
         return getOperand(0);
     }
     size_t argno() const {
         return argno_;
     }
     MDefinition *getValue() const {
         return getOperand(1);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::Any);
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MRunOncePrologue
   : public MNullaryInstruction
 {
   protected:
     MRunOncePrologue()
     {
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(RunOncePrologue)
     static MRunOncePrologue *New(TempAllocator &alloc) {
         return new(alloc) MRunOncePrologue();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Given a MIRType_Value A and a MIRType_Object B:
 // If the Value may be safely unboxed to an Object, return Object(A).
 // Otherwise, return B.
 // Used to implement return behavior for inlined constructors.
 class MReturnFromCtor
   : public MAryInstruction<2>,
     public MixPolicy<BoxPolicy<0>, ObjectPolicy<1> >
 {
     MReturnFromCtor(MDefinition *value, MDefinition *object) {
         setOperand(0, value);
         setOperand(1, object);
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(ReturnFromCtor)
     static MReturnFromCtor *New(TempAllocator &alloc, MDefinition *value, MDefinition *object)
     {
         return new(alloc) MReturnFromCtor(value, object);
     }
     MDefinition *getValue() const {
         return getOperand(0);
     }
     MDefinition *getObject() const {
         return getOperand(1);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 // Converts a primitive (either typed or untyped) to a double. If the input is
 // not primitive at runtime, a bailout occurs.
 class MToDouble
   : public MUnaryInstruction,
     public ToDoublePolicy
 {
   public:
     // Types of values which can be converted.
     enum ConversionKind {
         NonStringPrimitives,
         NonNullNonStringPrimitives,
         NumbersOnly
     };
   private:
     ConversionKind conversion_;
     MToDouble(MDefinition *def, ConversionKind conversion = NonStringPrimitives)
       : MUnaryInstruction(def), conversion_(conversion)
     {
         setResultType(MIRType_Double);
         setMovable();
         // An object might have "valueOf", which means it is effectful.
         if (def->mightBeType(MIRType_Object))
             setGuard();
     }
   public:
     INSTRUCTION_HEADER(ToDouble)
     static MToDouble *New(TempAllocator &alloc, MDefinition *def,
                           ConversionKind conversion = NonStringPrimitives)
     {
         return new(alloc) MToDouble(def, conversion);
     }
     static MToDouble *NewAsmJS(TempAllocator &alloc, MDefinition *def) {
         return new(alloc) MToDouble(def);
     }
     ConversionKind conversion() const {
         return conversion_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isToDouble() || ins->toToDouble()->conversion() != conversion())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
     bool truncate();
     bool isOperandTruncated(size_t index) const;
 #ifdef DEBUG
     bool isConsistentFloat32Use(MUse *use) const { return true; }
 #endif
 };
 // Converts a primitive (either typed or untyped) to a float32. If the input is
 // not primitive at runtime, a bailout occurs.
 class MToFloat32
   : public MUnaryInstruction,
     public ToDoublePolicy
 {
   public:
     // Types of values which can be converted.
     enum ConversionKind {
         NonStringPrimitives,
         NonNullNonStringPrimitives,
         NumbersOnly
     };
   protected:
     ConversionKind conversion_;
     MToFloat32(MDefinition *def, ConversionKind conversion)
       : MUnaryInstruction(def), conversion_(conversion)
     {
         setResultType(MIRType_Float32);
         setMovable();
         // An object might have "valueOf", which means it is effectful.
         if (def->mightBeType(MIRType_Object))
             setGuard();
     }
   public:
     INSTRUCTION_HEADER(ToFloat32)
     static MToFloat32 *New(TempAllocator &alloc, MDefinition *def,
                            ConversionKind conversion = NonStringPrimitives)
     {
         return new(alloc) MToFloat32(def, conversion);
     }
     static MToFloat32 *NewAsmJS(TempAllocator &alloc, MDefinition *def) {
         return new(alloc) MToFloat32(def, NonStringPrimitives);
     }
     ConversionKind conversion() const {
         return conversion_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     virtual MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isToFloat32() || ins->toToFloat32()->conversion() != conversion())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
     bool canConsumeFloat32(MUse *use) const { return true; }
     bool canProduceFloat32() const { return true; }
 };
 // Converts a uint32 to a double (coming from asm.js).
 class MAsmJSUnsignedToDouble
   : public MUnaryInstruction
 {
     MAsmJSUnsignedToDouble(MDefinition *def)
       : MUnaryInstruction(def)
     {
         setResultType(MIRType_Double);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(AsmJSUnsignedToDouble);
     static MAsmJSUnsignedToDouble *NewAsmJS(TempAllocator &alloc, MDefinition *def) {
         return new(alloc) MAsmJSUnsignedToDouble(def);
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // Converts a uint32 to a float32 (coming from asm.js).
 class MAsmJSUnsignedToFloat32
   : public MUnaryInstruction
 {
     MAsmJSUnsignedToFloat32(MDefinition *def)
       : MUnaryInstruction(def)
     {
         setResultType(MIRType_Float32);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(AsmJSUnsignedToFloat32);
     static MAsmJSUnsignedToFloat32 *NewAsmJS(TempAllocator &alloc, MDefinition *def) {
         return new(alloc) MAsmJSUnsignedToFloat32(def);
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool canProduceFloat32() const { return true; }
 };
 // Converts a primitive (either typed or untyped) to an int32. If the input is
 // not primitive at runtime, a bailout occurs. If the input cannot be converted
 // to an int32 without loss (i.e. "5.5" or undefined) then a bailout occurs.
 class MToInt32
   : public MUnaryInstruction,
     public ToInt32Policy
 {
     bool canBeNegativeZero_;
     MacroAssembler::IntConversionInputKind conversion_;
     MToInt32(MDefinition *def, MacroAssembler::IntConversionInputKind conversion)
       : MUnaryInstruction(def),
         canBeNegativeZero_(true),
         conversion_(conversion)
     {
         setResultType(MIRType_Int32);
         setMovable();
         // An object might have "valueOf", which means it is effectful.
         if (def->mightBeType(MIRType_Object))
             setGuard();
     }
   public:
     INSTRUCTION_HEADER(ToInt32)
     static MToInt32 *New(TempAllocator &alloc, MDefinition *def,
                          MacroAssembler::IntConversionInputKind conversion =
                              MacroAssembler::IntConversion_Any)
     {
         return new(alloc) MToInt32(def, conversion);
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     // this only has backwards information flow.
     void analyzeEdgeCasesBackward();
     bool canBeNegativeZero() const {
         return canBeNegativeZero_;
     }
     void setCanBeNegativeZero(bool negativeZero) {
         canBeNegativeZero_ = negativeZero;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MacroAssembler::IntConversionInputKind conversion() const {
         return conversion_;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
 #ifdef DEBUG
     bool isConsistentFloat32Use(MUse *use) const { return true; }
 #endif
 };
 // Converts a value or typed input to a truncated int32, for use with bitwise
 // operations. This is an infallible ValueToECMAInt32.
 class MTruncateToInt32 : public MUnaryInstruction
 {
     MTruncateToInt32(MDefinition *def)
       : MUnaryInstruction(def)
     {
         setResultType(MIRType_Int32);
         setMovable();
         // An object might have "valueOf", which means it is effectful.
         if (def->mightBeType(MIRType_Object))
             setGuard();
     }
   public:
     INSTRUCTION_HEADER(TruncateToInt32)
     static MTruncateToInt32 *New(TempAllocator &alloc, MDefinition *def) {
         return new(alloc) MTruncateToInt32(def);
     }
     static MTruncateToInt32 *NewAsmJS(TempAllocator &alloc, MDefinition *def) {
         return new(alloc) MTruncateToInt32(def);
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
     bool isOperandTruncated(size_t index) const;
 # ifdef DEBUG
     bool isConsistentFloat32Use(MUse *use) const {
         return true;
     }
 #endif
 };
 // Converts any type to a string
 class MToString : public MUnaryInstruction
 {
     MToString(MDefinition *def)
       : MUnaryInstruction(def)
     {
         // Converting an object to a string might be effectful.
         JS_ASSERT(!def->mightBeType(MIRType_Object));
         // NOP
         JS_ASSERT(def->type() != MIRType_String);
         setResultType(MIRType_String);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(ToString)
     static MToString *New(TempAllocator &alloc, MDefinition *def)
     {
         return new(alloc) MToString(def);
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         JS_ASSERT(!input()->mightBeType(MIRType_Object));
         return AliasSet::None();
     }
 };
 class MBitNot
   : public MUnaryInstruction,
     public BitwisePolicy
 {
   protected:
     MBitNot(MDefinition *input)
       : MUnaryInstruction(input)
     {
         setResultType(MIRType_Int32);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(BitNot)
     static MBitNot *New(TempAllocator &alloc, MDefinition *input);
     static MBitNot *NewAsmJS(TempAllocator &alloc, MDefinition *input);
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     void infer();
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         if (specialization_ == MIRType_None)
             return AliasSet::Store(AliasSet::Any);
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
 };
 class MTypeOf
   : public MUnaryInstruction,
     public BoxInputsPolicy
 {
     MIRType inputType_;
     bool inputMaybeCallableOrEmulatesUndefined_;
     MTypeOf(MDefinition *def, MIRType inputType)
       : MUnaryInstruction(def), inputType_(inputType),
         inputMaybeCallableOrEmulatesUndefined_(true)
     {
         setResultType(MIRType_String);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(TypeOf)
     static MTypeOf *New(TempAllocator &alloc, MDefinition *def, MIRType inputType) {
         return new(alloc) MTypeOf(def, inputType);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MIRType inputType() const {
         return inputType_;
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     void infer();
     bool inputMaybeCallableOrEmulatesUndefined() const {
         return inputMaybeCallableOrEmulatesUndefined_;
     }
     void markInputNotCallableOrEmulatesUndefined() {
         inputMaybeCallableOrEmulatesUndefined_ = false;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MToId
   : public MBinaryInstruction,
     public BoxInputsPolicy
 {
     MToId(MDefinition *object, MDefinition *index)
       : MBinaryInstruction(object, index)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(ToId)
     static MToId *New(TempAllocator &alloc, MDefinition *object, MDefinition *index) {
         return new(alloc) MToId(object, index);
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MBinaryBitwiseInstruction
   : public MBinaryInstruction,
     public BitwisePolicy
 {
   protected:
     MBinaryBitwiseInstruction(MDefinition *left, MDefinition *right)
       : MBinaryInstruction(left, right)
     {
         setResultType(MIRType_Int32);
         setMovable();
     }
     void specializeAsInt32();
   public:
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     MDefinition *foldUnnecessaryBitop();
     virtual MDefinition *foldIfZero(size_t operand) = 0;
     virtual MDefinition *foldIfNegOne(size_t operand) = 0;
     virtual MDefinition *foldIfEqual()  = 0;
     virtual void infer(BaselineInspector *inspector, jsbytecode *pc);
     bool congruentTo(const MDefinition *ins) const {
         return binaryCongruentTo(ins);
     }
     AliasSet getAliasSet() const {
         if (specialization_ >= MIRType_Object)
             return AliasSet::Store(AliasSet::Any);
         return AliasSet::None();
     }
     bool isOperandTruncated(size_t index) const;
 };
 class MBitAnd : public MBinaryBitwiseInstruction
 {
     MBitAnd(MDefinition *left, MDefinition *right)
       : MBinaryBitwiseInstruction(left, right)
     { }
   public:
     INSTRUCTION_HEADER(BitAnd)
     static MBitAnd *New(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     static MBitAnd *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     MDefinition *foldIfZero(size_t operand) {
         return getOperand(operand); // 0 & x => 0;
     }
     MDefinition *foldIfNegOne(size_t operand) {
         return getOperand(1 - operand); // x & -1 => x
     }
     MDefinition *foldIfEqual() {
         return getOperand(0); // x & x => x;
     }
     void computeRange(TempAllocator &alloc);
 };
 class MBitOr : public MBinaryBitwiseInstruction
 {
     MBitOr(MDefinition *left, MDefinition *right)
       : MBinaryBitwiseInstruction(left, right)
     { }
   public:
     INSTRUCTION_HEADER(BitOr)
     static MBitOr *New(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     static MBitOr *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     MDefinition *foldIfZero(size_t operand) {
         return getOperand(1 - operand); // 0 | x => x, so if ith is 0, return (1-i)th
     }
     MDefinition *foldIfNegOne(size_t operand) {
         return getOperand(operand); // x | -1 => -1
     }
     MDefinition *foldIfEqual() {
         return getOperand(0); // x | x => x
     }
     void computeRange(TempAllocator &alloc);
 };
 class MBitXor : public MBinaryBitwiseInstruction
 {
     MBitXor(MDefinition *left, MDefinition *right)
       : MBinaryBitwiseInstruction(left, right)
     { }
   public:
     INSTRUCTION_HEADER(BitXor)
     static MBitXor *New(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     static MBitXor *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     MDefinition *foldIfZero(size_t operand) {
         return getOperand(1 - operand); // 0 ^ x => x
     }
     MDefinition *foldIfNegOne(size_t operand) {
         return this;
     }
     MDefinition *foldIfEqual() {
         return this;
     }
     void computeRange(TempAllocator &alloc);
 };
 class MShiftInstruction
   : public MBinaryBitwiseInstruction
 {
   protected:
     MShiftInstruction(MDefinition *left, MDefinition *right)
       : MBinaryBitwiseInstruction(left, right)
     { }
   public:
     MDefinition *foldIfNegOne(size_t operand) {
         return this;
     }
     MDefinition *foldIfEqual() {
         return this;
     }
     virtual void infer(BaselineInspector *inspector, jsbytecode *pc);
 };
 class MLsh : public MShiftInstruction
 {
     MLsh(MDefinition *left, MDefinition *right)
       : MShiftInstruction(left, right)
     { }
   public:
     INSTRUCTION_HEADER(Lsh)
     static MLsh *New(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     static MLsh *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     MDefinition *foldIfZero(size_t operand) {
         // 0 << x => 0
         // x << 0 => x
         return getOperand(0);
     }
     void computeRange(TempAllocator &alloc);
 };
 class MRsh : public MShiftInstruction
 {
     MRsh(MDefinition *left, MDefinition *right)
       : MShiftInstruction(left, right)
     { }
   public:
     INSTRUCTION_HEADER(Rsh)
     static MRsh *New(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     static MRsh *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     MDefinition *foldIfZero(size_t operand) {
         // 0 >> x => 0
         // x >> 0 => x
         return getOperand(0);
     }
     void computeRange(TempAllocator &alloc);
 };
 class MUrsh : public MShiftInstruction
 {
     bool bailoutsDisabled_;
     MUrsh(MDefinition *left, MDefinition *right)
       : MShiftInstruction(left, right),
         bailoutsDisabled_(false)
     { }
   public:
     INSTRUCTION_HEADER(Ursh)
     static MUrsh *New(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     static MUrsh *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right);
     MDefinition *foldIfZero(size_t operand) {
         // 0 >>> x => 0
         if (operand == 0)
             return getOperand(0);
         return this;
     }
     void infer(BaselineInspector *inspector, jsbytecode *pc);
     bool bailoutsDisabled() const {
         return bailoutsDisabled_;
     }
     bool fallible() const;
     void computeRange(TempAllocator &alloc);
     void collectRangeInfoPreTrunc();
 };
 class MBinaryArithInstruction
   : public MBinaryInstruction,
     public ArithPolicy
 {
     // Implicit truncate flag is set by the truncate backward range analysis
     // optimization phase, and by asm.js pre-processing. It is used in
     // NeedNegativeZeroCheck to check if the result of a multiplication needs to
     // produce -0 double value, and for avoiding overflow checks.
     // This optimization happens when the multiplication cannot be truncated
     // even if all uses are truncating its result, such as when the range
     // analysis detect a precision loss in the multiplication.
     bool implicitTruncate_;
     void inferFallback(BaselineInspector *inspector, jsbytecode *pc);
   public:
     MBinaryArithInstruction(MDefinition *left, MDefinition *right)
       : MBinaryInstruction(left, right),
         implicitTruncate_(false)
     {
         setMovable();
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MIRType specialization() const {
         return specialization_;
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     virtual double getIdentity() = 0;
     void infer(TempAllocator &alloc, BaselineInspector *inspector, jsbytecode *pc);
     void setInt32() {
         specialization_ = MIRType_Int32;
         setResultType(MIRType_Int32);
     }
     virtual void trySpecializeFloat32(TempAllocator &alloc);
     bool congruentTo(const MDefinition *ins) const {
         return binaryCongruentTo(ins);
     }
     AliasSet getAliasSet() const {
         if (specialization_ >= MIRType_Object)
             return AliasSet::Store(AliasSet::Any);
         return AliasSet::None();
     }
     bool isTruncated() const {
         return implicitTruncate_;
     }
     void setTruncated(bool truncate) {
         implicitTruncate_ = truncate;
     }
 };
 class MMinMax
   : public MBinaryInstruction,
     public ArithPolicy
 {
     bool isMax_;
     MMinMax(MDefinition *left, MDefinition *right, MIRType type, bool isMax)
       : MBinaryInstruction(left, right),
         isMax_(isMax)
     {
         JS_ASSERT(type == MIRType_Double || type == MIRType_Int32);
         setResultType(type);
         setMovable();
         specialization_ = type;
     }
   public:
     INSTRUCTION_HEADER(MinMax)
     static MMinMax *New(TempAllocator &alloc, MDefinition *left, MDefinition *right, MIRType type,
                         bool isMax)
     {
         return new(alloc) MMinMax(left, right, type, isMax);
     }
     bool isMax() const {
         return isMax_;
     }
     MIRType specialization() const {
         return specialization_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isMinMax())
             return false;
         if (isMax() != ins->toMinMax()->isMax())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
 };
 class MAbs
   : public MUnaryInstruction,
     public ArithPolicy
 {
     bool implicitTruncate_;
     MAbs(MDefinition *num, MIRType type)
       : MUnaryInstruction(num),
         implicitTruncate_(false)
     {
         JS_ASSERT(IsNumberType(type));
         setResultType(type);
         setMovable();
         specialization_ = type;
     }
   public:
     INSTRUCTION_HEADER(Abs)
     static MAbs *New(TempAllocator &alloc, MDefinition *num, MIRType type) {
         return new(alloc) MAbs(num, type);
     }
     static MAbs *NewAsmJS(TempAllocator &alloc, MDefinition *num, MIRType type) {
         MAbs *ins = new(alloc) MAbs(num, type);
         if (type == MIRType_Int32)
             ins->implicitTruncate_ = true;
         return ins;
     }
     MDefinition *num() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     bool fallible() const;
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
     bool isFloat32Commutative() const { return true; }
     void trySpecializeFloat32(TempAllocator &alloc);
 };
 // Inline implementation of Math.sqrt().
 class MSqrt
   : public MUnaryInstruction,
     public FloatingPointPolicy<0>
 {
     MSqrt(MDefinition *num, MIRType type)
       : MUnaryInstruction(num)
     {
         setResultType(type);
         setPolicyType(type);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Sqrt)
     static MSqrt *New(TempAllocator &alloc, MDefinition *num) {
         return new(alloc) MSqrt(num, MIRType_Double);
     }
     static MSqrt *NewAsmJS(TempAllocator &alloc, MDefinition *num, MIRType type) {
         JS_ASSERT(IsFloatingPointType(type));
         return new(alloc) MSqrt(num, type);
     }
     MDefinition *num() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
     bool isFloat32Commutative() const { return true; }
     void trySpecializeFloat32(TempAllocator &alloc);
 };
 // Inline implementation of atan2 (arctangent of y/x).
 class MAtan2
   : public MBinaryInstruction,
     public MixPolicy<DoublePolicy<0>, DoublePolicy<1> >
 {
     MAtan2(MDefinition *y, MDefinition *x)
       : MBinaryInstruction(y, x)
     {
         setResultType(MIRType_Double);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Atan2)
     static MAtan2 *New(TempAllocator &alloc, MDefinition *y, MDefinition *x) {
         return new(alloc) MAtan2(y, x);
     }
     MDefinition *y() const {
         return getOperand(0);
     }
     MDefinition *x() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Inline implementation of Math.hypot().
 class MHypot
   : public MBinaryInstruction,
     public MixPolicy<DoublePolicy<0>, DoublePolicy<1> >
 {
     MHypot(MDefinition *y, MDefinition *x)
       : MBinaryInstruction(x, y)
     {
         setResultType(MIRType_Double);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Hypot)
     static MHypot *New(TempAllocator &alloc, MDefinition *x, MDefinition *y) {
         return new(alloc) MHypot(y, x);
     }
     MDefinition *x() const {
         return getOperand(0);
     }
     MDefinition *y() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Inline implementation of Math.pow().
 class MPow
   : public MBinaryInstruction,
     public PowPolicy
 {
     MPow(MDefinition *input, MDefinition *power, MIRType powerType)
       : MBinaryInstruction(input, power),
         PowPolicy(powerType)
     {
         setResultType(MIRType_Double);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Pow)
     static MPow *New(TempAllocator &alloc, MDefinition *input, MDefinition *power,
                      MIRType powerType)
     {
         JS_ASSERT(powerType == MIRType_Double || powerType == MIRType_Int32);
         return new(alloc) MPow(input, power, powerType);
     }
     MDefinition *input() const {
         return lhs();
     }
     MDefinition *power() const {
         return rhs();
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Inline implementation of Math.pow(x, 0.5), which subtly differs from Math.sqrt(x).
 class MPowHalf
   : public MUnaryInstruction,
     public DoublePolicy<0>
 {
     bool operandIsNeverNegativeInfinity_;
     bool operandIsNeverNegativeZero_;
     bool operandIsNeverNaN_;
     MPowHalf(MDefinition *input)
       : MUnaryInstruction(input),
         operandIsNeverNegativeInfinity_(false),
         operandIsNeverNegativeZero_(false),
         operandIsNeverNaN_(false)
     {
         setResultType(MIRType_Double);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(PowHalf)
     static MPowHalf *New(TempAllocator &alloc, MDefinition *input) {
         return new(alloc) MPowHalf(input);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     bool operandIsNeverNegativeInfinity() const {
         return operandIsNeverNegativeInfinity_;
     }
     bool operandIsNeverNegativeZero() const {
         return operandIsNeverNegativeZero_;
     }
     bool operandIsNeverNaN() const {
         return operandIsNeverNaN_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void collectRangeInfoPreTrunc();
 };
 // Inline implementation of Math.random().
 class MRandom : public MNullaryInstruction
 {
     MRandom()
     {
         setResultType(MIRType_Double);
     }
   public:
     INSTRUCTION_HEADER(Random)
     static MRandom *New(TempAllocator &alloc) {
         return new(alloc) MRandom;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
     void computeRange(TempAllocator &alloc);
 };
 class MMathFunction
   : public MUnaryInstruction,
     public FloatingPointPolicy<0>
 {
   public:
     enum Function {
         Log,
         Sin,
         Cos,
         Exp,
         Tan,
         ACos,
         ASin,
         ATan,
         Log10,
         Log2,
         Log1P,
         ExpM1,
         CosH,
         SinH,
         TanH,
         ACosH,
         ASinH,
         ATanH,
         Sign,
         Trunc,
         Cbrt,
         Floor,
         Ceil,
         Round
     };
   private:
     Function function_;
     const MathCache *cache_;
     MMathFunction(MDefinition *input, Function function, const MathCache *cache)
       : MUnaryInstruction(input), function_(function), cache_(cache)
     {
         setResultType(MIRType_Double);
         setPolicyType(MIRType_Double);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(MathFunction)
     // A nullptr cache means this function will neither access nor update the cache.
     static MMathFunction *New(TempAllocator &alloc, MDefinition *input, Function function,
                               const MathCache *cache)
     {
         return new(alloc) MMathFunction(input, function, cache);
     }
     Function function() const {
         return function_;
     }
     const MathCache *cache() const {
         return cache_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isMathFunction())
             return false;
         if (ins->toMathFunction()->function() != function())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
     void printOpcode(FILE *fp) const;
     static const char *FunctionName(Function function);
     bool isFloat32Commutative() const {
         return function_ == Floor || function_ == Ceil || function_ == Round;
     }
     void trySpecializeFloat32(TempAllocator &alloc);
     void computeRange(TempAllocator &alloc);
 };
 class MAdd : public MBinaryArithInstruction
 {
     // Is this instruction really an int at heart?
     MAdd(MDefinition *left, MDefinition *right)
       : MBinaryArithInstruction(left, right)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(Add)
     static MAdd *New(TempAllocator &alloc, MDefinition *left, MDefinition *right) {
         return new(alloc) MAdd(left, right);
     }
     static MAdd *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right,
                           MIRType type)
     {
         MAdd *add = new(alloc) MAdd(left, right);
         add->specialization_ = type;
         add->setResultType(type);
         if (type == MIRType_Int32) {
             add->setTruncated(true);
             add->setCommutative();
         }
         return add;
     }
     bool isFloat32Commutative() const { return true; }
     double getIdentity() {
         return 0;
     }
     bool fallible() const;
     void computeRange(TempAllocator &alloc);
     bool truncate();
     bool isOperandTruncated(size_t index) const;
 };
 class MSub : public MBinaryArithInstruction
 {
     MSub(MDefinition *left, MDefinition *right)
       : MBinaryArithInstruction(left, right)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(Sub)
     static MSub *New(TempAllocator &alloc, MDefinition *left, MDefinition *right) {
         return new(alloc) MSub(left, right);
     }
     static MSub *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right,
                           MIRType type)
     {
         MSub *sub = new(alloc) MSub(left, right);
         sub->specialization_ = type;
         sub->setResultType(type);
         if (type == MIRType_Int32)
             sub->setTruncated(true);
         return sub;
     }
     double getIdentity() {
         return 0;
     }
     bool isFloat32Commutative() const { return true; }
     bool fallible() const;
     void computeRange(TempAllocator &alloc);
     bool truncate();
     bool isOperandTruncated(size_t index) const;
 };
 class MMul : public MBinaryArithInstruction
 {
   public:
     enum Mode {
         Normal,
         Integer
     };
   private:
     // Annotation the result could be a negative zero
     // and we need to guard this during execution.
     bool canBeNegativeZero_;
     Mode mode_;
     MMul(MDefinition *left, MDefinition *right, MIRType type, Mode mode)
       : MBinaryArithInstruction(left, right),
         canBeNegativeZero_(true),
         mode_(mode)
     {
         if (mode == Integer) {
             // This implements the required behavior for Math.imul, which
             // can never fail and always truncates its output to int32.
             canBeNegativeZero_ = false;
             setTruncated(true);
             setCommutative();
         }
         JS_ASSERT_IF(mode != Integer, mode == Normal);
         if (type != MIRType_Value)
             specialization_ = type;
         setResultType(type);
     }
   public:
     INSTRUCTION_HEADER(Mul)
     static MMul *New(TempAllocator &alloc, MDefinition *left, MDefinition *right) {
         return new(alloc) MMul(left, right, MIRType_Value, MMul::Normal);
     }
     static MMul *New(TempAllocator &alloc, MDefinition *left, MDefinition *right, MIRType type,
                      Mode mode = Normal)
     {
         return new(alloc) MMul(left, right, type, mode);
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     void analyzeEdgeCasesForward();
     void analyzeEdgeCasesBackward();
     double getIdentity() {
         return 1;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isMul())
             return false;
         const MMul *mul = ins->toMul();
         if (canBeNegativeZero_ != mul->canBeNegativeZero())
             return false;
         if (mode_ != mul->mode())
             return false;
         return binaryCongruentTo(ins);
     }
     bool canOverflow() const;
     bool canBeNegativeZero() const {
         return canBeNegativeZero_;
     }
     void setCanBeNegativeZero(bool negativeZero) {
         canBeNegativeZero_ = negativeZero;
     }
     bool updateForReplacement(MDefinition *ins);
     bool fallible() const {
         return canBeNegativeZero_ || canOverflow();
     }
     void setSpecialization(MIRType type) {
         specialization_ = type;
     }
     bool isFloat32Commutative() const { return true; }
     void computeRange(TempAllocator &alloc);
     bool truncate();
     bool isOperandTruncated(size_t index) const;
     Mode mode() const { return mode_; }
 };
 class MDiv : public MBinaryArithInstruction
 {
     bool canBeNegativeZero_;
     bool canBeNegativeOverflow_;
     bool canBeDivideByZero_;
     bool canBeNegativeDividend_;
     bool unsigned_;
     // A Division can be truncated in 4 differents ways:
     //   1. Ignore Infinities (x / 0 --> 0).
     //   2. Ignore overflow (INT_MIN / -1 == (INT_MAX + 1) --> INT_MIN)
     //   3. Ignore negative zeros. (-0 --> 0)
     //   4. Ignore remainder. (3 / 4 --> 0)
     //
     // isTruncatedIndirectly is used to represent that we are interested in the
     // truncated result, but only if they it can safely flow in operations which
     // are computed modulo 2^32, such as (2) and (3).
     //
     // A division can return either Infinities (1) or a remainder (4) when both
     // operands are integers. Infinities are not safe, as they would have
     // absorbed other math operations. Remainders are not safe, as multiple can
     // add up to integers. This implies that we need to distinguish between a
     // division which is truncated directly (isTruncated) or which flow into
     // truncated operations (isTruncatedIndirectly).
     bool isTruncatedIndirectly_;
     MDiv(MDefinition *left, MDefinition *right, MIRType type)
       : MBinaryArithInstruction(left, right),
         canBeNegativeZero_(true),
         canBeNegativeOverflow_(true),
         canBeDivideByZero_(true),
         canBeNegativeDividend_(true),
         unsigned_(false),
         isTruncatedIndirectly_(false)
     {
         if (type != MIRType_Value)
             specialization_ = type;
         setResultType(type);
     }
   public:
     INSTRUCTION_HEADER(Div)
     static MDiv *New(TempAllocator &alloc, MDefinition *left, MDefinition *right) {
         return new(alloc) MDiv(left, right, MIRType_Value);
     }
     static MDiv *New(TempAllocator &alloc, MDefinition *left, MDefinition *right, MIRType type) {
         return new(alloc) MDiv(left, right, type);
     }
     static MDiv *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right,
                           MIRType type, bool unsignd)
     {
         MDiv *div = new(alloc) MDiv(left, right, type);
         div->unsigned_ = unsignd;
         if (type == MIRType_Int32)
             div->setTruncated(true);
         return div;
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     void analyzeEdgeCasesForward();
     void analyzeEdgeCasesBackward();
     double getIdentity() {
         MOZ_ASSUME_UNREACHABLE("not used");
     }
     bool canBeNegativeZero() const {
         return canBeNegativeZero_;
     }
     void setCanBeNegativeZero(bool negativeZero) {
         canBeNegativeZero_ = negativeZero;
     }
     bool canBeNegativeOverflow() const {
         return canBeNegativeOverflow_;
     }
     bool canBeDivideByZero() const {
         return canBeDivideByZero_;
     }
     bool canBeNegativeDividend() const {
         return canBeNegativeDividend_;
     }
     bool isUnsigned() const {
         return unsigned_;
     }
     bool isTruncatedIndirectly() const {
         return isTruncatedIndirectly_;
     }
     void setTruncatedIndirectly(bool truncate) {
         isTruncatedIndirectly_ = truncate;
     }
     bool canTruncateInfinities() const {
         return isTruncated();
     }
     bool canTruncateRemainder() const {
         return isTruncated();
     }
     bool canTruncateOverflow() const {
         return isTruncated() || isTruncatedIndirectly();
     }
     bool canTruncateNegativeZero() const {
         return isTruncated() || isTruncatedIndirectly();
     }
     bool isFloat32Commutative() const { return true; }
     void computeRange(TempAllocator &alloc);
     bool fallible() const;
     bool truncate();
     void collectRangeInfoPreTrunc();
 };
 class MMod : public MBinaryArithInstruction
 {
     bool unsigned_;
     bool canBeNegativeDividend_;
     MMod(MDefinition *left, MDefinition *right, MIRType type)
       : MBinaryArithInstruction(left, right),
         unsigned_(false),
         canBeNegativeDividend_(true)
     {
         if (type != MIRType_Value)
             specialization_ = type;
         setResultType(type);
     }
   public:
     INSTRUCTION_HEADER(Mod)
     static MMod *New(TempAllocator &alloc, MDefinition *left, MDefinition *right) {
         return new(alloc) MMod(left, right, MIRType_Value);
     }
     static MMod *NewAsmJS(TempAllocator &alloc, MDefinition *left, MDefinition *right,
                           MIRType type, bool unsignd)
     {
         MMod *mod = new(alloc) MMod(left, right, type);
         mod->unsigned_ = unsignd;
         if (type == MIRType_Int32)
             mod->setTruncated(true);
         return mod;
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     double getIdentity() {
         MOZ_ASSUME_UNREACHABLE("not used");
     }
     bool canBeNegativeDividend() const {
         JS_ASSERT(specialization_ == MIRType_Int32);
         return canBeNegativeDividend_;
     }
     bool canBeDivideByZero() const;
     bool canBePowerOfTwoDivisor() const;
     bool isUnsigned() const {
         return unsigned_;
     }
     bool fallible() const;
     void computeRange(TempAllocator &alloc);
     bool truncate();
     void collectRangeInfoPreTrunc();
 };
 class MConcat
   : public MBinaryInstruction,
     public MixPolicy<ConvertToStringPolicy<0>, ConvertToStringPolicy<1>>
 {
     MConcat(MDefinition *left, MDefinition *right)
       : MBinaryInstruction(left, right)
     {
         // At least one input should be definitely string
         JS_ASSERT(left->type() == MIRType_String || right->type() == MIRType_String);
         setMovable();
         setResultType(MIRType_String);
     }
   public:
     INSTRUCTION_HEADER(Concat)
     static MConcat *New(TempAllocator &alloc, MDefinition *left, MDefinition *right) {
         return new(alloc) MConcat(left, right);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MConcatPar
   : public MTernaryInstruction
 {
     MConcatPar(MDefinition *cx, MDefinition *left, MDefinition *right)
       : MTernaryInstruction(cx, left, right)
     {
         // Type analysis has already run, before replacing with the parallel
         // variant.
         JS_ASSERT(left->type() == MIRType_String && right->type() == MIRType_String);
         setMovable();
         setResultType(MIRType_String);
     }
   public:
     INSTRUCTION_HEADER(ConcatPar)
     static MConcatPar *New(TempAllocator &alloc, MDefinition *cx, MConcat *concat) {
         return new(alloc) MConcatPar(cx, concat->lhs(), concat->rhs());
     }
     MDefinition *forkJoinContext() const {
         return getOperand(0);
     }
     MDefinition *lhs() const {
         return getOperand(1);
     }
     MDefinition *rhs() const {
         return getOperand(2);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MCharCodeAt
   : public MBinaryInstruction,
     public MixPolicy<StringPolicy<0>, IntPolicy<1> >
 {
     MCharCodeAt(MDefinition *str, MDefinition *index)
         : MBinaryInstruction(str, index)
     {
         setMovable();
         setResultType(MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(CharCodeAt)
     static MCharCodeAt *New(TempAllocator &alloc, MDefinition *str, MDefinition *index) {
         return new(alloc) MCharCodeAt(str, index);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     virtual AliasSet getAliasSet() const {
         // Strings are immutable, so there is no implicit dependency.
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
 };
 class MFromCharCode
   : public MUnaryInstruction,
     public IntPolicy<0>
 {
     MFromCharCode(MDefinition *code)
       : MUnaryInstruction(code)
     {
         setMovable();
         setResultType(MIRType_String);
     }
   public:
     INSTRUCTION_HEADER(FromCharCode)
     static MFromCharCode *New(TempAllocator &alloc, MDefinition *code) {
         return new(alloc) MFromCharCode(code);
     }
     virtual AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MStringSplit
   : public MBinaryInstruction,
     public MixPolicy<StringPolicy<0>, StringPolicy<1> >
 {
     types::TypeObject *typeObject_;
     MStringSplit(types::CompilerConstraintList *constraints, MDefinition *string, MDefinition *sep,
                  JSObject *templateObject)
       : MBinaryInstruction(string, sep),
         typeObject_(templateObject->type())
     {
         setResultType(MIRType_Object);
         setResultTypeSet(MakeSingletonTypeSet(constraints, templateObject));
     }
   public:
     INSTRUCTION_HEADER(StringSplit)
     static MStringSplit *New(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                              MDefinition *string, MDefinition *sep,
                              JSObject *templateObject)
     {
         return new(alloc) MStringSplit(constraints, string, sep, templateObject);
     }
     types::TypeObject *typeObject() const {
         return typeObject_;
     }
     MDefinition *string() const {
         return getOperand(0);
     }
     MDefinition *separator() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
     virtual AliasSet getAliasSet() const {
         // Although this instruction returns a new array, we don't have to mark
         // it as store instruction, see also MNewArray.
         return AliasSet::None();
     }
 };
 // Returns an object to use as |this| value. See also ComputeThis and
 // BoxNonStrictThis in Interpreter.h.
 class MComputeThis
   : public MUnaryInstruction,
     public BoxPolicy<0>
 {
     MComputeThis(MDefinition *def)
       : MUnaryInstruction(def)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(ComputeThis)
     static MComputeThis *New(TempAllocator &alloc, MDefinition *def) {
         return new(alloc) MComputeThis(def);
     }
     MDefinition *input() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
     // Note: don't override getAliasSet: the thisObject hook can be
     // effectful.
 };
 // Load an arrow function's |this| value.
 class MLoadArrowThis
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MLoadArrowThis(MDefinition *callee)
       : MUnaryInstruction(callee)
     {
         setResultType(MIRType_Value);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(LoadArrowThis)
     static MLoadArrowThis *New(TempAllocator &alloc, MDefinition *callee) {
         return new(alloc) MLoadArrowThis(callee);
     }
     MDefinition *callee() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         // An arrow function's lexical |this| value is immutable.
         return AliasSet::None();
     }
 };
 class MPhi MOZ_FINAL : public MDefinition, public InlineForwardListNode<MPhi>
 {
     js::Vector<MUse, 2, IonAllocPolicy> inputs_;
     uint32_t slot_;
     bool hasBackedgeType_;
     bool triedToSpecialize_;
     bool isIterator_;
     bool canProduceFloat32_;
     bool canConsumeFloat32_;
 #if DEBUG
     bool specialized_;
     uint32_t capacity_;
 #endif
   protected:
     MUse *getUseFor(size_t index) {
         return &inputs_[index];
     }
   public:
     INSTRUCTION_HEADER(Phi)
     MPhi(TempAllocator &alloc, uint32_t slot, MIRType resultType)
       : inputs_(alloc),
         slot_(slot),
         hasBackedgeType_(false),
         triedToSpecialize_(false),
         isIterator_(false),
         canProduceFloat32_(false),
         canConsumeFloat32_(false)
 #if DEBUG
         , specialized_(false)
         , capacity_(0)
 #endif
     {
         setResultType(resultType);
     }
     static MPhi *New(TempAllocator &alloc, uint32_t slot, MIRType resultType = MIRType_Value) {
         return new(alloc) MPhi(alloc, slot, resultType);
     }
     void setOperand(size_t index, MDefinition *operand) {
         // Note: after the initial IonBuilder pass, it is OK to change phi
         // operands such that they do not include the type sets of their
         // operands. This can arise during e.g. value numbering, where
         // definitions producing the same value may have different type sets.
         JS_ASSERT(index < numOperands());
         inputs_[index].set(operand, this, index);
         operand->addUse(&inputs_[index]);
     }
     void removeOperand(size_t index);
     MDefinition *getOperand(size_t index) const {
         return inputs_[index].producer();
     }
     size_t numOperands() const {
         return inputs_.length();
     }
     uint32_t slot() const {
         return slot_;
     }
     bool hasBackedgeType() const {
         return hasBackedgeType_;
     }
     bool triedToSpecialize() const {
         return triedToSpecialize_;
     }
     void specialize(MIRType type) {
         triedToSpecialize_ = true;
         setResultType(type);
     }
     bool specializeType();
     // Whether this phi's type already includes information for def.
     bool typeIncludes(MDefinition *def);
     // Add types for this phi which speculate about new inputs that may come in
     // via a loop backedge.
     bool addBackedgeType(MIRType type, types::TemporaryTypeSet *typeSet);
     // Initializes the operands vector to the given capacity,
     // permitting use of addInput() instead of addInputSlow().
     bool reserveLength(size_t length);
     // Use only if capacity has been reserved by reserveLength
     void addInput(MDefinition *ins);
     // Appends a new input to the input vector. May call realloc_().
     // Prefer reserveLength() and addInput() instead, where possible.
     bool addInputSlow(MDefinition *ins, bool *ptypeChange = nullptr);
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     bool congruentTo(const MDefinition *ins) const;
     bool isIterator() const {
         return isIterator_;
     }
     void setIterator() {
         isIterator_ = true;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
     MDefinition *operandIfRedundant() {
         // If this phi is redundant (e.g., phi(a,a) or b=phi(a,this)),
         // returns the operand that it will always be equal to (a, in
         // those two cases).
         MDefinition *first = getOperand(0);
         for (size_t i = 1, e = numOperands(); i < e; i++) {
             if (getOperand(i) != first && getOperand(i) != this)
                 return nullptr;
         }
         return first;
     }
     bool canProduceFloat32() const {
         return canProduceFloat32_;
     }
     void setCanProduceFloat32(bool can) {
         canProduceFloat32_ = can;
     }
     bool canConsumeFloat32(MUse *use) const {
         return canConsumeFloat32_;
     }
     void setCanConsumeFloat32(bool can) {
         canConsumeFloat32_ = can;
     }
 };
 // The goal of a Beta node is to split a def at a conditionally taken
 // branch, so that uses dominated by it have a different name.
 class MBeta : public MUnaryInstruction
 {
   private:
     // This is the range induced by a comparison and branch in a preceding
     // block. Note that this does not reflect any range constraints from
     // the input value itself, so this value may differ from the range()
     // range after it is computed.
     const Range *comparison_;
     MBeta(MDefinition *val, const Range *comp)
         : MUnaryInstruction(val),
           comparison_(comp)
     {
         setResultType(val->type());
         setResultTypeSet(val->resultTypeSet());
     }
   public:
     INSTRUCTION_HEADER(Beta)
     void printOpcode(FILE *fp) const;
     static MBeta *New(TempAllocator &alloc, MDefinition *val, const Range *comp)
     {
         return new(alloc) MBeta(val, comp);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
 };
 // MIR representation of a Value on the OSR BaselineFrame.
 // The Value is indexed off of OsrFrameReg.
 class MOsrValue : public MUnaryInstruction
 {
   private:
     ptrdiff_t frameOffset_;
     MOsrValue(MOsrEntry *entry, ptrdiff_t frameOffset)
       : MUnaryInstruction(entry),
         frameOffset_(frameOffset)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(OsrValue)
     static MOsrValue *New(TempAllocator &alloc, MOsrEntry *entry, ptrdiff_t frameOffset) {
         return new(alloc) MOsrValue(entry, frameOffset);
     }
     ptrdiff_t frameOffset() const {
         return frameOffset_;
     }
     MOsrEntry *entry() {
         return getOperand(0)->toOsrEntry();
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // MIR representation of a JSObject scope chain pointer on the OSR BaselineFrame.
 // The pointer is indexed off of OsrFrameReg.
 class MOsrScopeChain : public MUnaryInstruction
 {
   private:
     MOsrScopeChain(MOsrEntry *entry)
       : MUnaryInstruction(entry)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(OsrScopeChain)
     static MOsrScopeChain *New(TempAllocator &alloc, MOsrEntry *entry) {
         return new(alloc) MOsrScopeChain(entry);
     }
     MOsrEntry *entry() {
         return getOperand(0)->toOsrEntry();
     }
 };
 // MIR representation of a JSObject ArgumentsObject pointer on the OSR BaselineFrame.
 // The pointer is indexed off of OsrFrameReg.
 class MOsrArgumentsObject : public MUnaryInstruction
 {
   private:
     MOsrArgumentsObject(MOsrEntry *entry)
       : MUnaryInstruction(entry)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(OsrArgumentsObject)
     static MOsrArgumentsObject *New(TempAllocator &alloc, MOsrEntry *entry) {
         return new(alloc) MOsrArgumentsObject(entry);
     }
     MOsrEntry *entry() {
         return getOperand(0)->toOsrEntry();
     }
 };
 // MIR representation of the return value on the OSR BaselineFrame.
 // The Value is indexed off of OsrFrameReg.
 class MOsrReturnValue : public MUnaryInstruction
 {
   private:
     MOsrReturnValue(MOsrEntry *entry)
       : MUnaryInstruction(entry)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(OsrReturnValue)
     static MOsrReturnValue *New(TempAllocator &alloc, MOsrEntry *entry) {
         return new(alloc) MOsrReturnValue(entry);
     }
     MOsrEntry *entry() {
         return getOperand(0)->toOsrEntry();
     }
 };
 // Check the current frame for over-recursion past the global stack limit.
 class MCheckOverRecursed : public MNullaryInstruction
 {
   public:
     INSTRUCTION_HEADER(CheckOverRecursed)
     static MCheckOverRecursed *New(TempAllocator &alloc) {
         return new(alloc) MCheckOverRecursed();
     }
 };
 // Check the current frame for over-recursion past the global stack limit.
 // Uses the per-thread recursion limit.
 class MCheckOverRecursedPar : public MUnaryInstruction
 {
     MCheckOverRecursedPar(MDefinition *cx)
       : MUnaryInstruction(cx)
     {
         setResultType(MIRType_None);
         setGuard();
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(CheckOverRecursedPar);
     static MCheckOverRecursedPar *New(TempAllocator &alloc, MDefinition *cx) {
         return new(alloc) MCheckOverRecursedPar(cx);
     }
     MDefinition *forkJoinContext() const {
         return getOperand(0);
     }
 };
 // Check for an interrupt (or rendezvous) in parallel mode.
 class MInterruptCheckPar : public MUnaryInstruction
 {
     MInterruptCheckPar(MDefinition *cx)
       : MUnaryInstruction(cx)
     {
         setResultType(MIRType_None);
         setGuard();
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(InterruptCheckPar);
     static MInterruptCheckPar *New(TempAllocator &alloc, MDefinition *cx) {
         return new(alloc) MInterruptCheckPar(cx);
     }
     MDefinition *forkJoinContext() const {
         return getOperand(0);
     }
 };
 // Check whether we need to fire the interrupt handler.
 class MInterruptCheck : public MNullaryInstruction
 {
     MInterruptCheck() {
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(InterruptCheck)
     static MInterruptCheck *New(TempAllocator &alloc) {
         return new(alloc) MInterruptCheck();
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // If not defined, set a global variable to |undefined|.
 class MDefVar : public MUnaryInstruction
 {
     CompilerRootPropertyName name_; // Target name to be defined.
     unsigned attrs_; // Attributes to be set.
   private:
     MDefVar(PropertyName *name, unsigned attrs, MDefinition *scopeChain)
       : MUnaryInstruction(scopeChain),
         name_(name),
         attrs_(attrs)
     {
     }
   public:
     INSTRUCTION_HEADER(DefVar)
     static MDefVar *New(TempAllocator &alloc, PropertyName *name, unsigned attrs,
                         MDefinition *scopeChain)
     {
         return new(alloc) MDefVar(name, attrs, scopeChain);
     }
     PropertyName *name() const {
         return name_;
     }
     unsigned attrs() const {
         return attrs_;
     }
     MDefinition *scopeChain() const {
         return getOperand(0);
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MDefFun : public MUnaryInstruction
 {
     CompilerRootFunction fun_;
   private:
     MDefFun(JSFunction *fun, MDefinition *scopeChain)
       : MUnaryInstruction(scopeChain),
         fun_(fun)
     {}
   public:
     INSTRUCTION_HEADER(DefFun)
     static MDefFun *New(TempAllocator &alloc, JSFunction *fun, MDefinition *scopeChain) {
         return new(alloc) MDefFun(fun, scopeChain);
     }
     JSFunction *fun() const {
         return fun_;
     }
     MDefinition *scopeChain() const {
         return getOperand(0);
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MRegExp : public MNullaryInstruction
 {
     CompilerRoot<RegExpObject *> source_;
     bool mustClone_;
     MRegExp(types::CompilerConstraintList *constraints, RegExpObject *source, bool mustClone)
       : source_(source),
         mustClone_(mustClone)
     {
         setResultType(MIRType_Object);
         setResultTypeSet(MakeSingletonTypeSet(constraints, source));
     }
   public:
     INSTRUCTION_HEADER(RegExp)
     static MRegExp *New(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                         RegExpObject *source, bool mustClone)
     {
         return new(alloc) MRegExp(constraints, source, mustClone);
     }
     bool mustClone() const {
         return mustClone_;
     }
     RegExpObject *source() const {
         return source_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MRegExpExec
   : public MBinaryInstruction,
     public MixPolicy<ConvertToStringPolicy<0>, ObjectPolicy<1>>
 {
   private:
     MRegExpExec(MDefinition *regexp, MDefinition *string)
       : MBinaryInstruction(string, regexp)
     {
         // May be object or null.
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(RegExpExec)
     static MRegExpExec *New(TempAllocator &alloc, MDefinition *regexp, MDefinition *string) {
         return new(alloc) MRegExpExec(regexp, string);
     }
     MDefinition *string() const {
         return getOperand(0);
     }
     MDefinition *regexp() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MRegExpTest
   : public MBinaryInstruction,
     public MixPolicy<ObjectPolicy<1>, ConvertToStringPolicy<0> >
 {
   private:
     MRegExpTest(MDefinition *regexp, MDefinition *string)
       : MBinaryInstruction(string, regexp)
     {
         setResultType(MIRType_Boolean);
     }
   public:
     INSTRUCTION_HEADER(RegExpTest)
     static MRegExpTest *New(TempAllocator &alloc, MDefinition *regexp, MDefinition *string) {
         return new(alloc) MRegExpTest(regexp, string);
     }
     MDefinition *string() const {
         return getOperand(0);
     }
     MDefinition *regexp() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 template <class Policy1>
 class MStrReplace
   : public MTernaryInstruction,
     public Mix3Policy<StringPolicy<0>, Policy1, StringPolicy<2> >
 {
   protected:
     MStrReplace(MDefinition *string, MDefinition *pattern, MDefinition *replacement)
       : MTernaryInstruction(string, pattern, replacement)
     {
         setMovable();
         setResultType(MIRType_String);
     }
   public:
     MDefinition *string() const {
         return getOperand(0);
     }
     MDefinition *pattern() const {
         return getOperand(1);
     }
     MDefinition *replacement() const {
         return getOperand(2);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MRegExpReplace
     : public MStrReplace< ObjectPolicy<1> >
 {
   private:
     MRegExpReplace(MDefinition *string, MDefinition *pattern, MDefinition *replacement)
       : MStrReplace< ObjectPolicy<1> >(string, pattern, replacement)
     {
     }
   public:
     INSTRUCTION_HEADER(RegExpReplace);
     static MRegExpReplace *New(TempAllocator &alloc, MDefinition *string, MDefinition *pattern, MDefinition *replacement) {
         return new(alloc) MRegExpReplace(string, pattern, replacement);
     }
 };
 class MStringReplace
     : public MStrReplace< StringPolicy<1> >
 {
   private:
     MStringReplace(MDefinition *string, MDefinition *pattern, MDefinition *replacement)
       : MStrReplace< StringPolicy<1> >(string, pattern, replacement)
     {
     }
   public:
     INSTRUCTION_HEADER(StringReplace);
     static MStringReplace *New(TempAllocator &alloc, MDefinition *string, MDefinition *pattern, MDefinition *replacement) {
         return new(alloc) MStringReplace(string, pattern, replacement);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 struct LambdaFunctionInfo
 {
     // The functions used in lambdas are the canonical original function in
     // the script, and are immutable except for delazification. Record this
     // information while still on the main thread to avoid races.
     CompilerRootFunction fun;
     uint16_t flags;
     gc::Cell *scriptOrLazyScript;
     bool singletonType;
     bool useNewTypeForClone;
     LambdaFunctionInfo(JSFunction *fun)
       : fun(fun), flags(fun->flags()),
         scriptOrLazyScript(fun->hasScript()
                            ? (gc::Cell *) fun->nonLazyScript()
                            : (gc::Cell *) fun->lazyScript()),
         singletonType(fun->hasSingletonType()),
         useNewTypeForClone(types::UseNewTypeForClone(fun))
     {}
     LambdaFunctionInfo(const LambdaFunctionInfo &info)
       : fun((JSFunction *) info.fun), flags(info.flags),
         scriptOrLazyScript(info.scriptOrLazyScript),
         singletonType(info.singletonType),
         useNewTypeForClone(info.useNewTypeForClone)
     {}
 };
 class MLambda
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     LambdaFunctionInfo info_;
     MLambda(types::CompilerConstraintList *constraints, MDefinition *scopeChain, JSFunction *fun)
       : MUnaryInstruction(scopeChain), info_(fun)
     {
         setResultType(MIRType_Object);
         if (!fun->hasSingletonType() && !types::UseNewTypeForClone(fun))
             setResultTypeSet(MakeSingletonTypeSet(constraints, fun));
     }
   public:
     INSTRUCTION_HEADER(Lambda)
     static MLambda *New(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                         MDefinition *scopeChain, JSFunction *fun)
     {
         return new(alloc) MLambda(constraints, scopeChain, fun);
     }
     MDefinition *scopeChain() const {
         return getOperand(0);
     }
     const LambdaFunctionInfo &info() const {
         return info_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MLambdaArrow
   : public MBinaryInstruction,
     public MixPolicy<ObjectPolicy<0>, BoxPolicy<1> >
 {
     LambdaFunctionInfo info_;
     MLambdaArrow(types::CompilerConstraintList *constraints, MDefinition *scopeChain,
                  MDefinition *this_, JSFunction *fun)
       : MBinaryInstruction(scopeChain, this_), info_(fun)
     {
         setResultType(MIRType_Object);
         MOZ_ASSERT(!types::UseNewTypeForClone(fun));
         if (!fun->hasSingletonType())
             setResultTypeSet(MakeSingletonTypeSet(constraints, fun));
     }
   public:
     INSTRUCTION_HEADER(LambdaArrow)
     static MLambdaArrow *New(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                              MDefinition *scopeChain, MDefinition *this_, JSFunction *fun)
     {
         return new(alloc) MLambdaArrow(constraints, scopeChain, this_, fun);
     }
     MDefinition *scopeChain() const {
         return getOperand(0);
     }
     MDefinition *thisDef() const {
         return getOperand(1);
     }
     const LambdaFunctionInfo &info() const {
         return info_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MLambdaPar
   : public MBinaryInstruction,
     public SingleObjectPolicy
 {
     LambdaFunctionInfo info_;
     MLambdaPar(MDefinition *cx, MDefinition *scopeChain, JSFunction *fun,
                types::TemporaryTypeSet *resultTypes, const LambdaFunctionInfo &info)
       : MBinaryInstruction(cx, scopeChain), info_(info)
     {
         JS_ASSERT(!info_.singletonType);
         JS_ASSERT(!info_.useNewTypeForClone);
         setResultType(MIRType_Object);
         setResultTypeSet(resultTypes);
     }
   public:
     INSTRUCTION_HEADER(LambdaPar);
     static MLambdaPar *New(TempAllocator &alloc, MDefinition *cx, MLambda *lambda) {
         return new(alloc) MLambdaPar(cx, lambda->scopeChain(), lambda->info().fun,
                                      lambda->resultTypeSet(), lambda->info());
     }
     MDefinition *forkJoinContext() const {
         return getOperand(0);
     }
     MDefinition *scopeChain() const {
         return getOperand(1);
     }
     const LambdaFunctionInfo &info() const {
         return info_;
     }
 };
 // Determines the implicit |this| value for function calls.
 class MImplicitThis
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MImplicitThis(MDefinition *callee)
       : MUnaryInstruction(callee)
     {
         setResultType(MIRType_Value);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(ImplicitThis)
     static MImplicitThis *New(TempAllocator &alloc, MDefinition *callee) {
         return new(alloc) MImplicitThis(callee);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *callee() const {
         return getOperand(0);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // Returns obj->slots.
 class MSlots
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MSlots(MDefinition *object)
       : MUnaryInstruction(object)
     {
         setResultType(MIRType_Slots);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Slots)
     static MSlots *New(TempAllocator &alloc, MDefinition *object) {
         return new(alloc) MSlots(object);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // Returns obj->elements.
 class MElements
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MElements(MDefinition *object)
       : MUnaryInstruction(object)
     {
         setResultType(MIRType_Elements);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Elements)
     static MElements *New(TempAllocator &alloc, MDefinition *object) {
         return new(alloc) MElements(object);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // A constant value for some object's array elements or typed array elements.
 class MConstantElements : public MNullaryInstruction
 {
     void *value_;
   protected:
     MConstantElements(void *v)
       : value_(v)
     {
         setResultType(MIRType_Elements);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(ConstantElements)
     static MConstantElements *New(TempAllocator &alloc, void *v) {
         return new(alloc) MConstantElements(v);
     }
     void *value() const {
         return value_;
     }
     void printOpcode(FILE *fp) const;
     HashNumber valueHash() const {
         return (HashNumber)(size_t) value_;
     }
     bool congruentTo(const MDefinition *ins) const {
         return ins->isConstantElements() && ins->toConstantElements()->value() == value();
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // Passes through an object's elements, after ensuring it is entirely doubles.
 class MConvertElementsToDoubles
   : public MUnaryInstruction
 {
     MConvertElementsToDoubles(MDefinition *elements)
       : MUnaryInstruction(elements)
     {
         setGuard();
         setMovable();
         setResultType(MIRType_Elements);
     }
   public:
     INSTRUCTION_HEADER(ConvertElementsToDoubles)
     static MConvertElementsToDoubles *New(TempAllocator &alloc, MDefinition *elements) {
         return new(alloc) MConvertElementsToDoubles(elements);
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         // This instruction can read and write to the elements' contents.
         // However, it is alright to hoist this from loops which explicitly
         // read or write to the elements: such reads and writes will use double
         // values and can be reordered freely wrt this conversion, except that
         // definite double loads must follow the conversion. The latter
         // property is ensured by chaining this instruction with the elements
         // themselves, in the same manner as MBoundsCheck.
         return AliasSet::None();
     }
 };
 // If |elements| has the CONVERT_DOUBLE_ELEMENTS flag, convert value to
 // double. Else return the original value.
 class MMaybeToDoubleElement
   : public MBinaryInstruction,
     public IntPolicy<1>
 {
     MMaybeToDoubleElement(MDefinition *elements, MDefinition *value)
       : MBinaryInstruction(elements, value)
     {
         JS_ASSERT(elements->type() == MIRType_Elements);
         setMovable();
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(MaybeToDoubleElement)
     static MMaybeToDoubleElement *New(TempAllocator &alloc, MDefinition *elements,
                                       MDefinition *value)
     {
         return new(alloc) MMaybeToDoubleElement(elements, value);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *value() const {
         return getOperand(1);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // Load the initialized length from an elements header.
 class MInitializedLength
   : public MUnaryInstruction
 {
     MInitializedLength(MDefinition *elements)
       : MUnaryInstruction(elements)
     {
         setResultType(MIRType_Int32);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(InitializedLength)
     static MInitializedLength *New(TempAllocator &alloc, MDefinition *elements) {
         return new(alloc) MInitializedLength(elements);
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
     void computeRange(TempAllocator &alloc);
 };
 // Store to the initialized length in an elements header. Note the input is an
 // *index*, one less than the desired length.
 class MSetInitializedLength
   : public MAryInstruction<2>
 {
     MSetInitializedLength(MDefinition *elements, MDefinition *index) {
         setOperand(0, elements);
         setOperand(1, index);
     }
   public:
     INSTRUCTION_HEADER(SetInitializedLength)
     static MSetInitializedLength *New(TempAllocator &alloc, MDefinition *elements, MDefinition *index) {
         return new(alloc) MSetInitializedLength(elements, index);
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::ObjectFields);
     }
 };
 // Load the array length from an elements header.
 class MArrayLength
   : public MUnaryInstruction
 {
     MArrayLength(MDefinition *elements)
       : MUnaryInstruction(elements)
     {
         setResultType(MIRType_Int32);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(ArrayLength)
     static MArrayLength *New(TempAllocator &alloc, MDefinition *elements) {
         return new(alloc) MArrayLength(elements);
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
     void computeRange(TempAllocator &alloc);
 };
 // Store to the length in an elements header. Note the input is an *index*, one
 // less than the desired length.
 class MSetArrayLength
   : public MAryInstruction<2>
 {
     MSetArrayLength(MDefinition *elements, MDefinition *index) {
         setOperand(0, elements);
         setOperand(1, index);
     }
   public:
     INSTRUCTION_HEADER(SetArrayLength)
     static MSetArrayLength *New(TempAllocator &alloc, MDefinition *elements, MDefinition *index) {
         return new(alloc) MSetArrayLength(elements, index);
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::ObjectFields);
     }
 };
 // Read the length of a typed array.
 class MTypedArrayLength
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MTypedArrayLength(MDefinition *obj)
       : MUnaryInstruction(obj)
     {
         setResultType(MIRType_Int32);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(TypedArrayLength)
     static MTypedArrayLength *New(TempAllocator &alloc, MDefinition *obj) {
         return new(alloc) MTypedArrayLength(obj);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::TypedArrayLength);
     }
     void computeRange(TempAllocator &alloc);
 };
 // Load a typed array's elements vector.
 class MTypedArrayElements
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MTypedArrayElements(MDefinition *object)
       : MUnaryInstruction(object)
     {
         setResultType(MIRType_Elements);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(TypedArrayElements)
     static MTypedArrayElements *New(TempAllocator &alloc, MDefinition *object) {
         return new(alloc) MTypedArrayElements(object);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // Checks whether a typed object is neutered.
 class MNeuterCheck
   : public MUnaryInstruction
 {
   private:
     MNeuterCheck(MDefinition *object)
       : MUnaryInstruction(object)
     {
         JS_ASSERT(object->type() == MIRType_Object);
         setResultType(MIRType_Object);
         setResultTypeSet(object->resultTypeSet());
         setGuard();
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(NeuterCheck)
     static MNeuterCheck *New(TempAllocator &alloc, MDefinition *object) {
         return new(alloc) MNeuterCheck(object);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // Load a binary data object's "elements", which is just its opaque
 // binary data space. Eventually this should probably be
 // unified with `MTypedArrayElements`.
 class MTypedObjectElements
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
   private:
     MTypedObjectElements(MDefinition *object)
       : MUnaryInstruction(object)
     {
         setResultType(MIRType_Elements);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(TypedObjectElements)
     static MTypedObjectElements *New(TempAllocator &alloc, MDefinition *object) {
         return new(alloc) MTypedObjectElements(object);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // Inlined version of the js::SetTypedObjectOffset() intrinsic.
 class MSetTypedObjectOffset
   : public MBinaryInstruction
 {
   private:
     MSetTypedObjectOffset(MDefinition *object, MDefinition *offset)
       : MBinaryInstruction(object, offset)
     {
         JS_ASSERT(object->type() == MIRType_Object);
         JS_ASSERT(offset->type() == MIRType_Int32);
         setResultType(MIRType_None);
     }
   public:
     INSTRUCTION_HEADER(SetTypedObjectOffset)
     static MSetTypedObjectOffset *New(TempAllocator &alloc,
                                       MDefinition *object,
                                       MDefinition *offset)
     {
         return new(alloc) MSetTypedObjectOffset(object, offset);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *offset() const {
         return getOperand(1);
     }
     AliasSet getAliasSet() const {
         // This affects the result of MTypedObjectElements,
         // which is described as a load of ObjectFields.
         return AliasSet::Store(AliasSet::ObjectFields);
     }
 };
 // Perform !-operation
 class MNot
   : public MUnaryInstruction,
     public TestPolicy
 {
     bool operandMightEmulateUndefined_;
     bool operandIsNeverNaN_;
   public:
     MNot(MDefinition *input)
       : MUnaryInstruction(input),
         operandMightEmulateUndefined_(true),
         operandIsNeverNaN_(false)
     {
         setResultType(MIRType_Boolean);
         setMovable();
     }
     static MNot *New(TempAllocator &alloc, MDefinition *elements) {
         return new(alloc) MNot(elements);
     }
     static MNot *NewAsmJS(TempAllocator &alloc, MDefinition *elements) {
         MNot *ins = new(alloc) MNot(elements);
         ins->setResultType(MIRType_Int32);
         return ins;
     }
     INSTRUCTION_HEADER(Not);
     void infer();
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     void markOperandCantEmulateUndefined() {
         operandMightEmulateUndefined_ = false;
     }
     bool operandMightEmulateUndefined() const {
         return operandMightEmulateUndefined_;
     }
     bool operandIsNeverNaN() const {
         return operandIsNeverNaN_;
     }
     MDefinition *operand() const {
         return getOperand(0);
     }
     virtual AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     TypePolicy *typePolicy() {
         return this;
     }
     void collectRangeInfoPreTrunc();
     void trySpecializeFloat32(TempAllocator &alloc);
     bool isFloat32Commutative() const { return true; }
 #ifdef DEBUG
     bool isConsistentFloat32Use(MUse *use) const {
         return true;
     }
 #endif
 };
 // Bailout if index + minimum < 0 or index + maximum >= length. The length used
 // in a bounds check must not be negative, or the wrong result may be computed
 // (unsigned comparisons may be used).
 class MBoundsCheck
   : public MBinaryInstruction
 {
     // Range over which to perform the bounds check, may be modified by GVN.
     int32_t minimum_;
     int32_t maximum_;
     MBoundsCheck(MDefinition *index, MDefinition *length)
       : MBinaryInstruction(index, length), minimum_(0), maximum_(0)
     {
         setGuard();
         setMovable();
         JS_ASSERT(index->type() == MIRType_Int32);
         JS_ASSERT(length->type() == MIRType_Int32);
         // Returns the checked index.
         setResultType(MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(BoundsCheck)
     static MBoundsCheck *New(TempAllocator &alloc, MDefinition *index, MDefinition *length) {
         return new(alloc) MBoundsCheck(index, length);
     }
     MDefinition *index() const {
         return getOperand(0);
     }
     MDefinition *length() const {
         return getOperand(1);
     }
     int32_t minimum() const {
         return minimum_;
     }
     void setMinimum(int32_t n) {
         minimum_ = n;
     }
     int32_t maximum() const {
         return maximum_;
     }
     void setMaximum(int32_t n) {
         maximum_ = n;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isBoundsCheck())
             return false;
         const MBoundsCheck *other = ins->toBoundsCheck();
         if (minimum() != other->minimum() || maximum() != other->maximum())
             return false;
         return congruentIfOperandsEqual(other);
     }
     virtual AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
 };
 // Bailout if index < minimum.
 class MBoundsCheckLower
   : public MUnaryInstruction
 {
     int32_t minimum_;
     bool fallible_;
     MBoundsCheckLower(MDefinition *index)
       : MUnaryInstruction(index), minimum_(0), fallible_(true)
     {
         setGuard();
         setMovable();
         JS_ASSERT(index->type() == MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(BoundsCheckLower)
     static MBoundsCheckLower *New(TempAllocator &alloc, MDefinition *index) {
         return new(alloc) MBoundsCheckLower(index);
     }
     MDefinition *index() const {
         return getOperand(0);
     }
     int32_t minimum() const {
         return minimum_;
     }
     void setMinimum(int32_t n) {
         minimum_ = n;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool fallible() const {
         return fallible_;
     }
     void collectRangeInfoPreTrunc();
 };
 // Load a value from a dense array's element vector and does a hole check if the
 // array is not known to be packed.
 class MLoadElement
   : public MBinaryInstruction,
     public SingleObjectPolicy
 {
     bool needsHoleCheck_;
     bool loadDoubles_;
     MLoadElement(MDefinition *elements, MDefinition *index, bool needsHoleCheck, bool loadDoubles)
       : MBinaryInstruction(elements, index),
         needsHoleCheck_(needsHoleCheck),
         loadDoubles_(loadDoubles)
     {
         if (needsHoleCheck) {
             // Uses may be optimized away based on this instruction's result
             // type. This means it's invalid to DCE this instruction, as we
             // have to invalidate when we read a hole.
             setGuard();
         }
         setResultType(MIRType_Value);
         setMovable();
         JS_ASSERT(elements->type() == MIRType_Elements);
         JS_ASSERT(index->type() == MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(LoadElement)
     static MLoadElement *New(TempAllocator &alloc, MDefinition *elements, MDefinition *index,
                              bool needsHoleCheck, bool loadDoubles) {
         return new(alloc) MLoadElement(elements, index, needsHoleCheck, loadDoubles);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     bool needsHoleCheck() const {
         return needsHoleCheck_;
     }
     bool loadDoubles() const {
         return loadDoubles_;
     }
     bool fallible() const {
         return needsHoleCheck();
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isLoadElement())
             return false;
         const MLoadElement *other = ins->toLoadElement();
         if (needsHoleCheck() != other->needsHoleCheck())
             return false;
         if (loadDoubles() != other->loadDoubles())
             return false;
         return congruentIfOperandsEqual(other);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::Element);
     }
 };
 // Load a value from a dense array's element vector. If the index is
 // out-of-bounds, or the indexed slot has a hole, undefined is returned
 // instead.
 class MLoadElementHole
   : public MTernaryInstruction,
     public SingleObjectPolicy
 {
     bool needsNegativeIntCheck_;
     bool needsHoleCheck_;
     MLoadElementHole(MDefinition *elements, MDefinition *index, MDefinition *initLength, bool needsHoleCheck)
       : MTernaryInstruction(elements, index, initLength),
         needsNegativeIntCheck_(true),
         needsHoleCheck_(needsHoleCheck)
     {
         setResultType(MIRType_Value);
         setMovable();
         JS_ASSERT(elements->type() == MIRType_Elements);
         JS_ASSERT(index->type() == MIRType_Int32);
         JS_ASSERT(initLength->type() == MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(LoadElementHole)
     static MLoadElementHole *New(TempAllocator &alloc, MDefinition *elements, MDefinition *index,
                                  MDefinition *initLength, bool needsHoleCheck) {
         return new(alloc) MLoadElementHole(elements, index, initLength, needsHoleCheck);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     MDefinition *initLength() const {
         return getOperand(2);
     }
     bool needsNegativeIntCheck() const {
         return needsNegativeIntCheck_;
     }
     bool needsHoleCheck() const {
         return needsHoleCheck_;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isLoadElementHole())
             return false;
         const MLoadElementHole *other = ins->toLoadElementHole();
         if (needsHoleCheck() != other->needsHoleCheck())
             return false;
         if (needsNegativeIntCheck() != other->needsNegativeIntCheck())
             return false;
         return congruentIfOperandsEqual(other);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::Element);
     }
     void collectRangeInfoPreTrunc();
 };
 class MStoreElementCommon
 {
     bool needsBarrier_;
     MIRType elementType_;
     bool racy_; // if true, exempted from normal data race req. during par. exec.
   protected:
     MStoreElementCommon()
       : needsBarrier_(false),
         elementType_(MIRType_Value),
         racy_(false)
     { }
   public:
     MIRType elementType() const {
         return elementType_;
     }
     void setElementType(MIRType elementType) {
         JS_ASSERT(elementType != MIRType_None);
         elementType_ = elementType;
     }
     bool needsBarrier() const {
         return needsBarrier_;
     }
     void setNeedsBarrier() {
         needsBarrier_ = true;
     }
     bool racy() const {
         return racy_;
     }
     void setRacy() {
         racy_ = true;
     }
 };
 // Store a value to a dense array slots vector.
 class MStoreElement
   : public MAryInstruction<3>,
     public MStoreElementCommon,
     public MixPolicy<SingleObjectPolicy, NoFloatPolicy<2> >
 {
     bool needsHoleCheck_;
     MStoreElement(MDefinition *elements, MDefinition *index, MDefinition *value, bool needsHoleCheck) {
         setOperand(0, elements);
         setOperand(1, index);
         setOperand(2, value);
         needsHoleCheck_ = needsHoleCheck;
         JS_ASSERT(elements->type() == MIRType_Elements);
         JS_ASSERT(index->type() == MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(StoreElement)
     static MStoreElement *New(TempAllocator &alloc, MDefinition *elements, MDefinition *index,
                               MDefinition *value, bool needsHoleCheck) {
         return new(alloc) MStoreElement(elements, index, value, needsHoleCheck);
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     MDefinition *value() const {
         return getOperand(2);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::Element);
     }
     bool needsHoleCheck() const {
         return needsHoleCheck_;
     }
     bool fallible() const {
         return needsHoleCheck();
     }
 };
 // Like MStoreElement, but supports indexes >= initialized length. The downside
 // is that we cannot hoist the elements vector and bounds check, since this
 // instruction may update the (initialized) length and reallocate the elements
 // vector.
 class MStoreElementHole
   : public MAryInstruction<4>,
     public MStoreElementCommon,
     public MixPolicy<SingleObjectPolicy, NoFloatPolicy<3> >
 {
     MStoreElementHole(MDefinition *object, MDefinition *elements,
                       MDefinition *index, MDefinition *value) {
         setOperand(0, object);
         setOperand(1, elements);
         setOperand(2, index);
         setOperand(3, value);
         JS_ASSERT(elements->type() == MIRType_Elements);
         JS_ASSERT(index->type() == MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(StoreElementHole)
     static MStoreElementHole *New(TempAllocator &alloc, MDefinition *object, MDefinition *elements,
                                   MDefinition *index, MDefinition *value) {
         return new(alloc) MStoreElementHole(object, elements, index, value);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *elements() const {
         return getOperand(1);
     }
     MDefinition *index() const {
         return getOperand(2);
     }
     MDefinition *value() const {
         return getOperand(3);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         // StoreElementHole can update the initialized length, the array length
         // or reallocate obj->elements.
         return AliasSet::Store(AliasSet::Element | AliasSet::ObjectFields);
     }
 };
 // Array.prototype.pop or Array.prototype.shift on a dense array.
 class MArrayPopShift
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
   public:
     enum Mode {
         Pop,
         Shift
     };
   private:
     Mode mode_;
     bool needsHoleCheck_;
     bool maybeUndefined_;
     MArrayPopShift(MDefinition *object, Mode mode, bool needsHoleCheck, bool maybeUndefined)
       : MUnaryInstruction(object), mode_(mode), needsHoleCheck_(needsHoleCheck),
         maybeUndefined_(maybeUndefined)
     { }
   public:
     INSTRUCTION_HEADER(ArrayPopShift)
     static MArrayPopShift *New(TempAllocator &alloc, MDefinition *object, Mode mode,
                                bool needsHoleCheck, bool maybeUndefined)
     {
         return new(alloc) MArrayPopShift(object, mode, needsHoleCheck, maybeUndefined);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     bool needsHoleCheck() const {
         return needsHoleCheck_;
     }
     bool maybeUndefined() const {
         return maybeUndefined_;
     }
     bool mode() const {
         return mode_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::Element | AliasSet::ObjectFields);
     }
 };
 // Array.prototype.push on a dense array. Returns the new array length.
 class MArrayPush
   : public MBinaryInstruction,
     public MixPolicy<SingleObjectPolicy, NoFloatPolicy<1> >
 {
     MArrayPush(MDefinition *object, MDefinition *value)
       : MBinaryInstruction(object, value)
     {
         setResultType(MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(ArrayPush)
     static MArrayPush *New(TempAllocator &alloc, MDefinition *object, MDefinition *value) {
         return new(alloc) MArrayPush(object, value);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *value() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::Element | AliasSet::ObjectFields);
     }
     void computeRange(TempAllocator &alloc);
 };
 // Array.prototype.concat on two dense arrays.
 class MArrayConcat
   : public MBinaryInstruction,
     public MixPolicy<ObjectPolicy<0>, ObjectPolicy<1> >
 {
     CompilerRootObject templateObj_;
     gc::InitialHeap initialHeap_;
     MArrayConcat(types::CompilerConstraintList *constraints, MDefinition *lhs, MDefinition *rhs,
                  JSObject *templateObj, gc::InitialHeap initialHeap)
       : MBinaryInstruction(lhs, rhs),
         templateObj_(templateObj),
         initialHeap_(initialHeap)
     {
         setResultType(MIRType_Object);
         setResultTypeSet(MakeSingletonTypeSet(constraints, templateObj));
     }
   public:
     INSTRUCTION_HEADER(ArrayConcat)
     static MArrayConcat *New(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                              MDefinition *lhs, MDefinition *rhs,
                              JSObject *templateObj, gc::InitialHeap initialHeap)
     {
         return new(alloc) MArrayConcat(constraints, lhs, rhs, templateObj, initialHeap);
     }
     JSObject *templateObj() const {
         return templateObj_;
     }
     gc::InitialHeap initialHeap() const {
         return initialHeap_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::Element | AliasSet::ObjectFields);
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MLoadTypedArrayElement
   : public MBinaryInstruction
 {
     ScalarTypeDescr::Type arrayType_;
     MLoadTypedArrayElement(MDefinition *elements, MDefinition *index,
                            ScalarTypeDescr::Type arrayType)
       : MBinaryInstruction(elements, index), arrayType_(arrayType)
     {
         setResultType(MIRType_Value);
         setMovable();
         JS_ASSERT(elements->type() == MIRType_Elements);
         JS_ASSERT(index->type() == MIRType_Int32);
         JS_ASSERT(arrayType >= 0 && arrayType < ScalarTypeDescr::TYPE_MAX);
     }
   public:
     INSTRUCTION_HEADER(LoadTypedArrayElement)
     static MLoadTypedArrayElement *New(TempAllocator &alloc, MDefinition *elements, MDefinition *index,
                                        ScalarTypeDescr::Type arrayType)
     {
         return new(alloc) MLoadTypedArrayElement(elements, index, arrayType);
     }
     ScalarTypeDescr::Type arrayType() const {
         return arrayType_;
     }
     bool fallible() const {
         // Bailout if the result does not fit in an int32.
         return arrayType_ == ScalarTypeDescr::TYPE_UINT32 && type() == MIRType_Int32;
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::TypedArrayElement);
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isLoadTypedArrayElement())
             return false;
         const MLoadTypedArrayElement *other = ins->toLoadTypedArrayElement();
         if (arrayType_ != other->arrayType_)
             return false;
         return congruentIfOperandsEqual(other);
     }
     void printOpcode(FILE *fp) const;
     void computeRange(TempAllocator &alloc);
     bool canProduceFloat32() const { return arrayType_ == ScalarTypeDescr::TYPE_FLOAT32; }
 };
 // Load a value from a typed array. Out-of-bounds accesses are handled using
 // a VM call.
 class MLoadTypedArrayElementHole
   : public MBinaryInstruction,
     public SingleObjectPolicy
 {
     int arrayType_;
     bool allowDouble_;
     MLoadTypedArrayElementHole(MDefinition *object, MDefinition *index, int arrayType, bool allowDouble)
       : MBinaryInstruction(object, index), arrayType_(arrayType), allowDouble_(allowDouble)
     {
         setResultType(MIRType_Value);
         setMovable();
         JS_ASSERT(index->type() == MIRType_Int32);
         JS_ASSERT(arrayType >= 0 && arrayType < ScalarTypeDescr::TYPE_MAX);
     }
   public:
     INSTRUCTION_HEADER(LoadTypedArrayElementHole)
     static MLoadTypedArrayElementHole *New(TempAllocator &alloc, MDefinition *object, MDefinition *index,
                                            int arrayType, bool allowDouble)
     {
         return new(alloc) MLoadTypedArrayElementHole(object, index, arrayType, allowDouble);
     }
     int arrayType() const {
         return arrayType_;
     }
     bool allowDouble() const {
         return allowDouble_;
     }
     bool fallible() const {
         return arrayType_ == ScalarTypeDescr::TYPE_UINT32 && !allowDouble_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isLoadTypedArrayElementHole())
             return false;
         const MLoadTypedArrayElementHole *other = ins->toLoadTypedArrayElementHole();
         if (arrayType() != other->arrayType())
             return false;
         if (allowDouble() != other->allowDouble())
             return false;
         return congruentIfOperandsEqual(other);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::TypedArrayElement);
     }
     bool canProduceFloat32() const { return arrayType_ == ScalarTypeDescr::TYPE_FLOAT32; }
 };
 // Load a value fallibly or infallibly from a statically known typed array.
 class MLoadTypedArrayElementStatic
   : public MUnaryInstruction,
     public ConvertToInt32Policy<0>
 {
     MLoadTypedArrayElementStatic(TypedArrayObject *typedArray, MDefinition *ptr)
       : MUnaryInstruction(ptr), typedArray_(typedArray), fallible_(true)
     {
         int type = typedArray_->type();
         if (type == ScalarTypeDescr::TYPE_FLOAT32)
             setResultType(MIRType_Float32);
         else if (type == ScalarTypeDescr::TYPE_FLOAT64)
             setResultType(MIRType_Double);
         else
             setResultType(MIRType_Int32);
     }
     CompilerRoot<TypedArrayObject*> typedArray_;
     bool fallible_;
   public:
     INSTRUCTION_HEADER(LoadTypedArrayElementStatic);
     static MLoadTypedArrayElementStatic *New(TempAllocator &alloc, TypedArrayObject *typedArray,
                                              MDefinition *ptr)
     {
         return new(alloc) MLoadTypedArrayElementStatic(typedArray, ptr);
     }
     ArrayBufferView::ViewType viewType() const {
         return (ArrayBufferView::ViewType) typedArray_->type();
     }
     void *base() const;
     size_t length() const;
     MDefinition *ptr() const { return getOperand(0); }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::TypedArrayElement);
     }
     bool fallible() const {
         return fallible_;
     }
     void setInfallible() {
         fallible_ = false;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     void computeRange(TempAllocator &alloc);
     bool truncate();
     bool canProduceFloat32() const { return typedArray_->type() == ScalarTypeDescr::TYPE_FLOAT32; }
 };
 class MStoreTypedArrayElement
   : public MTernaryInstruction,
     public StoreTypedArrayPolicy
 {
     int arrayType_;
     // See note in MStoreElementCommon.
     bool racy_;
     MStoreTypedArrayElement(MDefinition *elements, MDefinition *index, MDefinition *value,
                             int arrayType)
       : MTernaryInstruction(elements, index, value), arrayType_(arrayType), racy_(false)
     {
         setMovable();
         JS_ASSERT(elements->type() == MIRType_Elements);
         JS_ASSERT(index->type() == MIRType_Int32);
         JS_ASSERT(arrayType >= 0 && arrayType < ScalarTypeDescr::TYPE_MAX);
     }
   public:
     INSTRUCTION_HEADER(StoreTypedArrayElement)
     static MStoreTypedArrayElement *New(TempAllocator &alloc, MDefinition *elements, MDefinition *index,
                                         MDefinition *value, int arrayType)
     {
         return new(alloc) MStoreTypedArrayElement(elements, index, value, arrayType);
     }
     int arrayType() const {
         return arrayType_;
     }
     bool isByteArray() const {
         return (arrayType_ == ScalarTypeDescr::TYPE_INT8 ||
                 arrayType_ == ScalarTypeDescr::TYPE_UINT8 ||
                 arrayType_ == ScalarTypeDescr::TYPE_UINT8_CLAMPED);
     }
     bool isFloatArray() const {
         return (arrayType_ == ScalarTypeDescr::TYPE_FLOAT32 ||
                 arrayType_ == ScalarTypeDescr::TYPE_FLOAT64);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     MDefinition *value() const {
         return getOperand(2);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::TypedArrayElement);
     }
     bool racy() const {
         return racy_;
     }
     void setRacy() {
         racy_ = true;
     }
     bool isOperandTruncated(size_t index) const;
     bool canConsumeFloat32(MUse *use) const {
         return use->index() == 2 && arrayType_ == ScalarTypeDescr::TYPE_FLOAT32;
     }
 };
 class MStoreTypedArrayElementHole
   : public MAryInstruction<4>,
     public StoreTypedArrayHolePolicy
 {
     int arrayType_;
     MStoreTypedArrayElementHole(MDefinition *elements, MDefinition *length, MDefinition *index,
                                 MDefinition *value, int arrayType)
       : MAryInstruction<4>(), arrayType_(arrayType)
     {
         setOperand(0, elements);
         setOperand(1, length);
         setOperand(2, index);
         setOperand(3, value);
         setMovable();
         JS_ASSERT(elements->type() == MIRType_Elements);
         JS_ASSERT(length->type() == MIRType_Int32);
         JS_ASSERT(index->type() == MIRType_Int32);
         JS_ASSERT(arrayType >= 0 && arrayType < ScalarTypeDescr::TYPE_MAX);
     }
   public:
     INSTRUCTION_HEADER(StoreTypedArrayElementHole)
     static MStoreTypedArrayElementHole *New(TempAllocator &alloc, MDefinition *elements,
                                             MDefinition *length, MDefinition *index,
                                             MDefinition *value, int arrayType)
     {
         return new(alloc) MStoreTypedArrayElementHole(elements, length, index, value, arrayType);
     }
     int arrayType() const {
         return arrayType_;
     }
     bool isByteArray() const {
         return (arrayType_ == ScalarTypeDescr::TYPE_INT8 ||
                 arrayType_ == ScalarTypeDescr::TYPE_UINT8 ||
                 arrayType_ == ScalarTypeDescr::TYPE_UINT8_CLAMPED);
     }
     bool isFloatArray() const {
         return (arrayType_ == ScalarTypeDescr::TYPE_FLOAT32 ||
                 arrayType_ == ScalarTypeDescr::TYPE_FLOAT64);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *length() const {
         return getOperand(1);
     }
     MDefinition *index() const {
         return getOperand(2);
     }
     MDefinition *value() const {
         return getOperand(3);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::TypedArrayElement);
     }
     bool isOperandTruncated(size_t index) const;
     bool canConsumeFloat32(MUse *use) const {
         return use->index() == 3 && arrayType_ == ScalarTypeDescr::TYPE_FLOAT32;
     }
 };
 // Store a value infallibly to a statically known typed array.
 class MStoreTypedArrayElementStatic :
     public MBinaryInstruction
   , public StoreTypedArrayElementStaticPolicy
 {
     MStoreTypedArrayElementStatic(TypedArrayObject *typedArray, MDefinition *ptr, MDefinition *v)
       : MBinaryInstruction(ptr, v), typedArray_(typedArray)
     {}
     CompilerRoot<TypedArrayObject*> typedArray_;
   public:
     INSTRUCTION_HEADER(StoreTypedArrayElementStatic);
     static MStoreTypedArrayElementStatic *New(TempAllocator &alloc, TypedArrayObject *typedArray,
                                               MDefinition *ptr, MDefinition *v)
     {
         return new(alloc) MStoreTypedArrayElementStatic(typedArray, ptr, v);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     ArrayBufferView::ViewType viewType() const {
         return (ArrayBufferView::ViewType) typedArray_->type();
     }
     bool isFloatArray() const {
         return (viewType() == ArrayBufferView::TYPE_FLOAT32 ||
                 viewType() == ArrayBufferView::TYPE_FLOAT64);
     }
     void *base() const;
     size_t length() const;
     MDefinition *ptr() const { return getOperand(0); }
     MDefinition *value() const { return getOperand(1); }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::TypedArrayElement);
     }
     bool isOperandTruncated(size_t index) const;
     bool canConsumeFloat32(MUse *use) const {
         return use->index() == 1 && typedArray_->type() == ScalarTypeDescr::TYPE_FLOAT32;
     }
 };
 // Compute an "effective address", i.e., a compound computation of the form:
 //   base + index * scale + displacement
 class MEffectiveAddress : public MBinaryInstruction
 {
     MEffectiveAddress(MDefinition *base, MDefinition *index, Scale scale, int32_t displacement)
       : MBinaryInstruction(base, index), scale_(scale), displacement_(displacement)
     {
         JS_ASSERT(base->type() == MIRType_Int32);
         JS_ASSERT(index->type() == MIRType_Int32);
         setMovable();
         setResultType(MIRType_Int32);
     }
     Scale scale_;
     int32_t displacement_;
   public:
     INSTRUCTION_HEADER(EffectiveAddress);
     static MEffectiveAddress *New(TempAllocator &alloc, MDefinition *base, MDefinition *index,
                                   Scale s, int32_t d)
     {
         return new(alloc) MEffectiveAddress(base, index, s, d);
     }
     MDefinition *base() const {
         return lhs();
     }
     MDefinition *index() const {
         return rhs();
     }
     Scale scale() const {
         return scale_;
     }
     int32_t displacement() const {
         return displacement_;
     }
 };
 // Clamp input to range [0, 255] for Uint8ClampedArray.
 class MClampToUint8
   : public MUnaryInstruction,
     public ClampPolicy
 {
     MClampToUint8(MDefinition *input)
       : MUnaryInstruction(input)
     {
         setResultType(MIRType_Int32);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(ClampToUint8)
     static MClampToUint8 *New(TempAllocator &alloc, MDefinition *input) {
         return new(alloc) MClampToUint8(input);
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
 };
 class MLoadFixedSlot
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     size_t slot_;
   protected:
     MLoadFixedSlot(MDefinition *obj, size_t slot)
       : MUnaryInstruction(obj), slot_(slot)
     {
         setResultType(MIRType_Value);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(LoadFixedSlot)
     static MLoadFixedSlot *New(TempAllocator &alloc, MDefinition *obj, size_t slot) {
         return new(alloc) MLoadFixedSlot(obj, slot);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     size_t slot() const {
         return slot_;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isLoadFixedSlot())
             return false;
         if (slot() != ins->toLoadFixedSlot()->slot())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::FixedSlot);
     }
     bool mightAlias(const MDefinition *store) const;
 };
 class MStoreFixedSlot
   : public MBinaryInstruction,
     public MixPolicy<SingleObjectPolicy, NoFloatPolicy<1> >
 {
     bool needsBarrier_;
     size_t slot_;
     MStoreFixedSlot(MDefinition *obj, MDefinition *rval, size_t slot, bool barrier)
       : MBinaryInstruction(obj, rval),
         needsBarrier_(barrier),
         slot_(slot)
     { }
   public:
     INSTRUCTION_HEADER(StoreFixedSlot)
     static MStoreFixedSlot *New(TempAllocator &alloc, MDefinition *obj, size_t slot,
                                 MDefinition *rval)
     {
         return new(alloc) MStoreFixedSlot(obj, rval, slot, false);
     }
     static MStoreFixedSlot *NewBarriered(TempAllocator &alloc, MDefinition *obj, size_t slot,
                                          MDefinition *rval)
     {
         return new(alloc) MStoreFixedSlot(obj, rval, slot, true);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *value() const {
         return getOperand(1);
     }
     size_t slot() const {
         return slot_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::FixedSlot);
     }
     bool needsBarrier() const {
         return needsBarrier_;
     }
     void setNeedsBarrier() {
         needsBarrier_ = true;
     }
 };
 typedef Vector<JSObject *, 4, IonAllocPolicy> ObjectVector;
 typedef Vector<bool, 4, IonAllocPolicy> BoolVector;
 class InlinePropertyTable : public TempObject
 {
     struct Entry : public TempObject {
         CompilerRoot<types::TypeObject *> typeObj;
         CompilerRootFunction func;
         Entry(types::TypeObject *typeObj, JSFunction *func)
           : typeObj(typeObj), func(func)
         { }
     };
     jsbytecode *pc_;
     MResumePoint *priorResumePoint_;
     Vector<Entry *, 4, IonAllocPolicy> entries_;
   public:
     InlinePropertyTable(TempAllocator &alloc, jsbytecode *pc)
       : pc_(pc), priorResumePoint_(nullptr), entries_(alloc)
     { }
     void setPriorResumePoint(MResumePoint *resumePoint) {
         JS_ASSERT(priorResumePoint_ == nullptr);
         priorResumePoint_ = resumePoint;
     }
     MResumePoint *priorResumePoint() const {
         return priorResumePoint_;
     }
     jsbytecode *pc() const {
         return pc_;
     }
     bool addEntry(TempAllocator &alloc, types::TypeObject *typeObj, JSFunction *func) {
         return entries_.append(new(alloc) Entry(typeObj, func));
     }
     size_t numEntries() const {
         return entries_.length();
     }
     types::TypeObject *getTypeObject(size_t i) const {
         JS_ASSERT(i < numEntries());
         return entries_[i]->typeObj;
     }
     JSFunction *getFunction(size_t i) const {
         JS_ASSERT(i < numEntries());
         return entries_[i]->func;
     }
     bool hasFunction(JSFunction *func) const;
     types::TemporaryTypeSet *buildTypeSetForFunction(JSFunction *func) const;
     // Remove targets that vetoed inlining from the InlinePropertyTable.
     void trimTo(ObjectVector &targets, BoolVector &choiceSet);
     // Ensure that the InlinePropertyTable's domain is a subset of |targets|.
     void trimToTargets(ObjectVector &targets);
 };
 class CacheLocationList : public InlineConcatList<CacheLocationList>
 {
   public:
     CacheLocationList()
       : pc(nullptr),
         script(nullptr)
     { }
     jsbytecode *pc;
     JSScript *script;
 };
 class MGetPropertyCache
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     CompilerRootPropertyName name_;
     bool idempotent_;
     bool monitoredResult_;
     CacheLocationList location_;
     InlinePropertyTable *inlinePropertyTable_;
     MGetPropertyCache(MDefinition *obj, PropertyName *name, bool monitoredResult)
       : MUnaryInstruction(obj),
         name_(name),
         idempotent_(false),
         monitoredResult_(monitoredResult),
         location_(),
         inlinePropertyTable_(nullptr)
     {
         setResultType(MIRType_Value);
         // The cache will invalidate if there are objects with e.g. lookup or
         // resolve hooks on the proto chain. setGuard ensures this check is not
         // eliminated.
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(GetPropertyCache)
     static MGetPropertyCache *New(TempAllocator &alloc, MDefinition *obj, PropertyName *name,
                                   bool monitoredResult) {
         return new(alloc) MGetPropertyCache(obj, name, monitoredResult);
     }
     InlinePropertyTable *initInlinePropertyTable(TempAllocator &alloc, jsbytecode *pc) {
         JS_ASSERT(inlinePropertyTable_ == nullptr);
         inlinePropertyTable_ = new(alloc) InlinePropertyTable(alloc, pc);
         return inlinePropertyTable_;
     }
     void clearInlinePropertyTable() {
         inlinePropertyTable_ = nullptr;
     }
     InlinePropertyTable *propTable() const {
         return inlinePropertyTable_;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     PropertyName *name() const {
         return name_;
     }
     bool idempotent() const {
         return idempotent_;
     }
     void setIdempotent() {
         idempotent_ = true;
         setMovable();
     }
     bool monitoredResult() const {
         return monitoredResult_;
     }
     CacheLocationList &location() {
         return location_;
     }
     TypePolicy *typePolicy() { return this; }
     bool congruentTo(const MDefinition *ins) const {
         if (!idempotent_)
             return false;
         if (!ins->isGetPropertyCache())
             return false;
         if (name() != ins->toGetPropertyCache()->name())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         if (idempotent_) {
             return AliasSet::Load(AliasSet::ObjectFields |
                                   AliasSet::FixedSlot |
                                   AliasSet::DynamicSlot);
         }
         return AliasSet::Store(AliasSet::Any);
     }
     void setBlock(MBasicBlock *block);
     bool updateForReplacement(MDefinition *ins);
 };
 // Emit code to load a value from an object's slots if its shape matches
 // one of the shapes observed by the baseline IC, else bails out.
 class MGetPropertyPolymorphic
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     struct Entry {
         // The shape to guard against.
         Shape *objShape;
         // The property to laod.
         Shape *shape;
     };
     Vector<Entry, 4, IonAllocPolicy> shapes_;
     CompilerRootPropertyName name_;
     MGetPropertyPolymorphic(TempAllocator &alloc, MDefinition *obj, PropertyName *name)
       : MUnaryInstruction(obj),
         shapes_(alloc),
         name_(name)
     {
         setGuard();
         setMovable();
         setResultType(MIRType_Value);
     }
     PropertyName *name() const {
         return name_;
     }
   public:
     INSTRUCTION_HEADER(GetPropertyPolymorphic)
     static MGetPropertyPolymorphic *New(TempAllocator &alloc, MDefinition *obj, PropertyName *name) {
         return new(alloc) MGetPropertyPolymorphic(alloc, obj, name);
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isGetPropertyPolymorphic())
             return false;
         if (name() != ins->toGetPropertyPolymorphic()->name())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool addShape(Shape *objShape, Shape *shape) {
         Entry entry;
         entry.objShape = objShape;
         entry.shape = shape;
         return shapes_.append(entry);
     }
     size_t numShapes() const {
         return shapes_.length();
     }
     Shape *objShape(size_t i) const {
         return shapes_[i].objShape;
     }
     Shape *shape(size_t i) const {
         return shapes_[i].shape;
     }
     MDefinition *obj() const {
         return getOperand(0);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields | AliasSet::FixedSlot | AliasSet::DynamicSlot);
     }
     bool mightAlias(const MDefinition *store) const;
 };
 // Emit code to store a value to an object's slots if its shape matches
 // one of the shapes observed by the baseline IC, else bails out.
 class MSetPropertyPolymorphic
   : public MBinaryInstruction,
     public SingleObjectPolicy
 {
     struct Entry {
         // The shape to guard against.
         Shape *objShape;
         // The property to laod.
         Shape *shape;
     };
     Vector<Entry, 4, IonAllocPolicy> shapes_;
     bool needsBarrier_;
     MSetPropertyPolymorphic(TempAllocator &alloc, MDefinition *obj, MDefinition *value)
       : MBinaryInstruction(obj, value),
         shapes_(alloc),
         needsBarrier_(false)
     {
     }
   public:
     INSTRUCTION_HEADER(SetPropertyPolymorphic)
     static MSetPropertyPolymorphic *New(TempAllocator &alloc, MDefinition *obj, MDefinition *value) {
         return new(alloc) MSetPropertyPolymorphic(alloc, obj, value);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool addShape(Shape *objShape, Shape *shape) {
         Entry entry;
         entry.objShape = objShape;
         entry.shape = shape;
         return shapes_.append(entry);
     }
     size_t numShapes() const {
         return shapes_.length();
     }
     Shape *objShape(size_t i) const {
         return shapes_[i].objShape;
     }
     Shape *shape(size_t i) const {
         return shapes_[i].shape;
     }
     MDefinition *obj() const {
         return getOperand(0);
     }
     MDefinition *value() const {
         return getOperand(1);
     }
     bool needsBarrier() const {
         return needsBarrier_;
     }
     void setNeedsBarrier() {
         needsBarrier_ = true;
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::ObjectFields | AliasSet::FixedSlot | AliasSet::DynamicSlot);
     }
 };
 class MDispatchInstruction
   : public MControlInstruction,
     public SingleObjectPolicy
 {
     // Map from JSFunction* -> MBasicBlock.
     struct Entry {
         JSFunction *func;
         MBasicBlock *block;
         Entry(JSFunction *func, MBasicBlock *block)
           : func(func), block(block)
         { }
     };
     Vector<Entry, 4, IonAllocPolicy> map_;
     // An optional fallback path that uses MCall.
     MBasicBlock *fallback_;
     MUse operand_;
   public:
     MDispatchInstruction(TempAllocator &alloc, MDefinition *input)
       : map_(alloc), fallback_(nullptr)
     {
         setOperand(0, input);
     }
   protected:
     void setOperand(size_t index, MDefinition *operand) MOZ_FINAL MOZ_OVERRIDE {
         JS_ASSERT(index == 0);
         operand_.set(operand, this, 0);
         operand->addUse(&operand_);
     }
     MUse *getUseFor(size_t index) MOZ_FINAL MOZ_OVERRIDE {
         JS_ASSERT(index == 0);
         return &operand_;
     }
     MDefinition *getOperand(size_t index) const MOZ_FINAL MOZ_OVERRIDE {
         JS_ASSERT(index == 0);
         return operand_.producer();
     }
     size_t numOperands() const MOZ_FINAL MOZ_OVERRIDE {
         return 1;
     }
   public:
     void setSuccessor(size_t i, MBasicBlock *successor) {
         JS_ASSERT(i < numSuccessors());
         if (i == map_.length())
             fallback_ = successor;
         else
             map_[i].block = successor;
     }
     size_t numSuccessors() const MOZ_FINAL MOZ_OVERRIDE {
         return map_.length() + (fallback_ ? 1 : 0);
     }
     void replaceSuccessor(size_t i, MBasicBlock *successor) MOZ_FINAL MOZ_OVERRIDE {
         setSuccessor(i, successor);
     }
     MBasicBlock *getSuccessor(size_t i) const MOZ_FINAL MOZ_OVERRIDE {
         JS_ASSERT(i < numSuccessors());
         if (i == map_.length())
             return fallback_;
         return map_[i].block;
     }
   public:
     void addCase(JSFunction *func, MBasicBlock *block) {
         map_.append(Entry(func, block));
     }
     uint32_t numCases() const {
         return map_.length();
     }
     JSFunction *getCase(uint32_t i) const {
         return map_[i].func;
     }
     MBasicBlock *getCaseBlock(uint32_t i) const {
         return map_[i].block;
     }
     bool hasFallback() const {
         return bool(fallback_);
     }
     void addFallback(MBasicBlock *block) {
         JS_ASSERT(!hasFallback());
         fallback_ = block;
     }
     MBasicBlock *getFallback() const {
         JS_ASSERT(hasFallback());
         return fallback_;
     }
   public:
     MDefinition *input() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 // Polymorphic dispatch for inlining, keyed off incoming TypeObject.
 class MTypeObjectDispatch : public MDispatchInstruction
 {
     // Map TypeObject (of CallProp's Target Object) -> JSFunction (yielded by the CallProp).
     InlinePropertyTable *inlinePropertyTable_;
     MTypeObjectDispatch(TempAllocator &alloc, MDefinition *input, InlinePropertyTable *table)
       : MDispatchInstruction(alloc, input),
         inlinePropertyTable_(table)
     { }
   public:
     INSTRUCTION_HEADER(TypeObjectDispatch)
     static MTypeObjectDispatch *New(TempAllocator &alloc, MDefinition *ins,
                                     InlinePropertyTable *table)
     {
         return new(alloc) MTypeObjectDispatch(alloc, ins, table);
     }
     InlinePropertyTable *propTable() const {
         return inlinePropertyTable_;
     }
 };
 // Polymorphic dispatch for inlining, keyed off incoming JSFunction*.
 class MFunctionDispatch : public MDispatchInstruction
 {
     MFunctionDispatch(TempAllocator &alloc, MDefinition *input)
       : MDispatchInstruction(alloc, input)
     { }
   public:
     INSTRUCTION_HEADER(FunctionDispatch)
     static MFunctionDispatch *New(TempAllocator &alloc, MDefinition *ins) {
         return new(alloc) MFunctionDispatch(alloc, ins);
     }
 };
 class MGetElementCache
   : public MBinaryInstruction
 {
     MixPolicy<ObjectPolicy<0>, BoxPolicy<1> > PolicyV;
     MixPolicy<ObjectPolicy<0>, IntPolicy<1> > PolicyT;
     // See the comment in IonBuilder::jsop_getelem.
     bool monitoredResult_;
     MGetElementCache(MDefinition *obj, MDefinition *value, bool monitoredResult)
       : MBinaryInstruction(obj, value), monitoredResult_(monitoredResult)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(GetElementCache)
     static MGetElementCache *New(TempAllocator &alloc, MDefinition *obj, MDefinition *value,
                                  bool monitoredResult)
     {
         return new(alloc) MGetElementCache(obj, value, monitoredResult);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     bool monitoredResult() const {
         return monitoredResult_;
     }
     bool allowDoubleResult() const;
     TypePolicy *typePolicy() {
         if (type() == MIRType_Value)
             return &PolicyV;
         return &PolicyT;
     }
 };
 class MBindNameCache
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     CompilerRootPropertyName name_;
     CompilerRootScript script_;
     jsbytecode *pc_;
     MBindNameCache(MDefinition *scopeChain, PropertyName *name, JSScript *script, jsbytecode *pc)
       : MUnaryInstruction(scopeChain), name_(name), script_(script), pc_(pc)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(BindNameCache)
     static MBindNameCache *New(TempAllocator &alloc, MDefinition *scopeChain, PropertyName *name,
                                JSScript *script, jsbytecode *pc)
     {
         return new(alloc) MBindNameCache(scopeChain, name, script, pc);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *scopeChain() const {
         return getOperand(0);
     }
     PropertyName *name() const {
         return name_;
     }
     JSScript *script() const {
         return script_;
     }
     jsbytecode *pc() const {
         return pc_;
     }
 };
 // Guard on an object's shape.
 class MGuardShape
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     CompilerRootShape shape_;
     BailoutKind bailoutKind_;
     MGuardShape(MDefinition *obj, Shape *shape, BailoutKind bailoutKind)
       : MUnaryInstruction(obj),
         shape_(shape),
         bailoutKind_(bailoutKind)
     {
         setGuard();
         setMovable();
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(GuardShape)
     static MGuardShape *New(TempAllocator &alloc, MDefinition *obj, Shape *shape,
                             BailoutKind bailoutKind)
     {
         return new(alloc) MGuardShape(obj, shape, bailoutKind);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *obj() const {
         return getOperand(0);
     }
     const Shape *shape() const {
         return shape_;
     }
     BailoutKind bailoutKind() const {
         return bailoutKind_;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isGuardShape())
             return false;
         if (shape() != ins->toGuardShape()->shape())
             return false;
         if (bailoutKind() != ins->toGuardShape()->bailoutKind())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // Guard on an object's type, inclusively or exclusively.
 class MGuardObjectType
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     CompilerRoot<types::TypeObject *> typeObject_;
     bool bailOnEquality_;
     MGuardObjectType(MDefinition *obj, types::TypeObject *typeObject, bool bailOnEquality)
       : MUnaryInstruction(obj),
         typeObject_(typeObject),
         bailOnEquality_(bailOnEquality)
     {
         setGuard();
         setMovable();
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(GuardObjectType)
     static MGuardObjectType *New(TempAllocator &alloc, MDefinition *obj, types::TypeObject *typeObject,
                                  bool bailOnEquality) {
         return new(alloc) MGuardObjectType(obj, typeObject, bailOnEquality);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *obj() const {
         return getOperand(0);
     }
     const types::TypeObject *typeObject() const {
         return typeObject_;
     }
     bool bailOnEquality() const {
         return bailOnEquality_;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isGuardObjectType())
             return false;
         if (typeObject() != ins->toGuardObjectType()->typeObject())
             return false;
         if (bailOnEquality() != ins->toGuardObjectType()->bailOnEquality())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // Guard on an object's identity, inclusively or exclusively.
 class MGuardObjectIdentity
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     CompilerRoot<JSObject *> singleObject_;
     bool bailOnEquality_;
     MGuardObjectIdentity(MDefinition *obj, JSObject *singleObject, bool bailOnEquality)
       : MUnaryInstruction(obj),
         singleObject_(singleObject),
         bailOnEquality_(bailOnEquality)
     {
         setGuard();
         setMovable();
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(GuardObjectIdentity)
     static MGuardObjectIdentity *New(TempAllocator &alloc, MDefinition *obj, JSObject *singleObject,
                                      bool bailOnEquality) {
         return new(alloc) MGuardObjectIdentity(obj, singleObject, bailOnEquality);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *obj() const {
         return getOperand(0);
     }
     JSObject *singleObject() const {
         return singleObject_;
     }
     bool bailOnEquality() const {
         return bailOnEquality_;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isGuardObjectIdentity())
             return false;
         if (singleObject() != ins->toGuardObjectIdentity()->singleObject())
             return false;
         if (bailOnEquality() != ins->toGuardObjectIdentity()->bailOnEquality())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // Guard on an object's class.
 class MGuardClass
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     const Class *class_;
     MGuardClass(MDefinition *obj, const Class *clasp)
       : MUnaryInstruction(obj),
         class_(clasp)
     {
         setGuard();
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(GuardClass)
     static MGuardClass *New(TempAllocator &alloc, MDefinition *obj, const Class *clasp) {
         return new(alloc) MGuardClass(obj, clasp);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *obj() const {
         return getOperand(0);
     }
     const Class *getClass() const {
         return class_;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isGuardClass())
             return false;
         if (getClass() != ins->toGuardClass()->getClass())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::ObjectFields);
     }
 };
 // Load from vp[slot] (slots that are not inline in an object).
 class MLoadSlot
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     uint32_t slot_;
     MLoadSlot(MDefinition *slots, uint32_t slot)
       : MUnaryInstruction(slots),
         slot_(slot)
     {
         setResultType(MIRType_Value);
         setMovable();
         JS_ASSERT(slots->type() == MIRType_Slots);
     }
   public:
     INSTRUCTION_HEADER(LoadSlot)
     static MLoadSlot *New(TempAllocator &alloc, MDefinition *slots, uint32_t slot) {
         return new(alloc) MLoadSlot(slots, slot);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *slots() const {
         return getOperand(0);
     }
     uint32_t slot() const {
         return slot_;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isLoadSlot())
             return false;
         if (slot() != ins->toLoadSlot()->slot())
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         JS_ASSERT(slots()->type() == MIRType_Slots);
         return AliasSet::Load(AliasSet::DynamicSlot);
     }
     bool mightAlias(const MDefinition *store) const;
 };
 // Inline call to access a function's environment (scope chain).
 class MFunctionEnvironment
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
   public:
     MFunctionEnvironment(MDefinition *function)
         : MUnaryInstruction(function)
     {
         setResultType(MIRType_Object);
         setMovable();
     }
     INSTRUCTION_HEADER(FunctionEnvironment)
     static MFunctionEnvironment *New(TempAllocator &alloc, MDefinition *function) {
         return new(alloc) MFunctionEnvironment(function);
     }
     MDefinition *function() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     // A function's environment is fixed.
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // Loads the current js::ForkJoinContext*.
 // Only applicable in ParallelExecution.
 class MForkJoinContext
   : public MNullaryInstruction
 {
     MForkJoinContext()
         : MNullaryInstruction()
     {
         setResultType(MIRType_ForkJoinContext);
     }
   public:
     INSTRUCTION_HEADER(ForkJoinContext);
     static MForkJoinContext *New(TempAllocator &alloc) {
         return new(alloc) MForkJoinContext();
     }
     AliasSet getAliasSet() const {
         // Indicate that this instruction reads nothing, stores nothing.
         // (For all intents and purposes)
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Calls the ForkJoinGetSlice stub, used for inlining the eponymous intrinsic.
 // Only applicable in ParallelExecution.
 class MForkJoinGetSlice
   : public MUnaryInstruction
 {
     MForkJoinGetSlice(MDefinition *cx)
       : MUnaryInstruction(cx)
     {
         setResultType(MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(ForkJoinGetSlice);
     static MForkJoinGetSlice *New(TempAllocator &alloc, MDefinition *cx) {
         return new(alloc) MForkJoinGetSlice(cx);
     }
     MDefinition *forkJoinContext() {
         return getOperand(0);
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Store to vp[slot] (slots that are not inline in an object).
 class MStoreSlot
   : public MBinaryInstruction,
     public MixPolicy<ObjectPolicy<0>, NoFloatPolicy<1> >
 {
     uint32_t slot_;
     MIRType slotType_;
     bool needsBarrier_;
     MStoreSlot(MDefinition *slots, uint32_t slot, MDefinition *value, bool barrier)
         : MBinaryInstruction(slots, value),
           slot_(slot),
           slotType_(MIRType_Value),
           needsBarrier_(barrier)
     {
         JS_ASSERT(slots->type() == MIRType_Slots);
     }
   public:
     INSTRUCTION_HEADER(StoreSlot)
     static MStoreSlot *New(TempAllocator &alloc, MDefinition *slots, uint32_t slot,
                            MDefinition *value)
     {
         return new(alloc) MStoreSlot(slots, slot, value, false);
     }
     static MStoreSlot *NewBarriered(TempAllocator &alloc, MDefinition *slots, uint32_t slot,
                                     MDefinition *value)
     {
         return new(alloc) MStoreSlot(slots, slot, value, true);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *slots() const {
         return getOperand(0);
     }
     MDefinition *value() const {
         return getOperand(1);
     }
     uint32_t slot() const {
         return slot_;
     }
     MIRType slotType() const {
         return slotType_;
     }
     void setSlotType(MIRType slotType) {
         JS_ASSERT(slotType != MIRType_None);
         slotType_ = slotType;
     }
     bool needsBarrier() const {
         return needsBarrier_;
     }
     void setNeedsBarrier() {
         needsBarrier_ = true;
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::DynamicSlot);
     }
 };
 class MGetNameCache
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
   public:
     enum AccessKind {
         NAMETYPEOF,
         NAME
     };
   private:
     CompilerRootPropertyName name_;
     AccessKind kind_;
     MGetNameCache(MDefinition *obj, PropertyName *name, AccessKind kind)
       : MUnaryInstruction(obj),
         name_(name),
         kind_(kind)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(GetNameCache)
     static MGetNameCache *New(TempAllocator &alloc, MDefinition *obj, PropertyName *name,
                               AccessKind kind)
     {
         return new(alloc) MGetNameCache(obj, name, kind);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *scopeObj() const {
         return getOperand(0);
     }
     PropertyName *name() const {
         return name_;
     }
     AccessKind accessKind() const {
         return kind_;
     }
 };
 class MCallGetIntrinsicValue : public MNullaryInstruction
 {
     CompilerRootPropertyName name_;
     MCallGetIntrinsicValue(PropertyName *name)
       : name_(name)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(CallGetIntrinsicValue)
     static MCallGetIntrinsicValue *New(TempAllocator &alloc, PropertyName *name) {
         return new(alloc) MCallGetIntrinsicValue(name);
     }
     PropertyName *name() const {
         return name_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MCallsiteCloneCache
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     jsbytecode *callPc_;
     MCallsiteCloneCache(MDefinition *callee, jsbytecode *callPc)
       : MUnaryInstruction(callee),
         callPc_(callPc)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(CallsiteCloneCache);
     static MCallsiteCloneCache *New(TempAllocator &alloc, MDefinition *callee, jsbytecode *callPc) {
         return new(alloc) MCallsiteCloneCache(callee, callPc);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *callee() const {
         return getOperand(0);
     }
     jsbytecode *callPc() const {
         return callPc_;
     }
     // Callsite cloning is idempotent.
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MSetPropertyInstruction : public MBinaryInstruction
 {
     CompilerRootPropertyName name_;
     bool strict_;
     bool needsBarrier_;
   protected:
     MSetPropertyInstruction(MDefinition *obj, MDefinition *value, PropertyName *name,
                             bool strict)
       : MBinaryInstruction(obj, value),
         name_(name), strict_(strict), needsBarrier_(true)
     {}
   public:
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *value() const {
         return getOperand(1);
     }
     PropertyName *name() const {
         return name_;
     }
     bool strict() const {
         return strict_;
     }
     bool needsBarrier() const {
         return needsBarrier_;
     }
     void setNeedsBarrier() {
         needsBarrier_ = true;
     }
 };
 class MSetElementInstruction
   : public MTernaryInstruction
 {
   protected:
     MSetElementInstruction(MDefinition *object, MDefinition *index, MDefinition *value)
       : MTernaryInstruction(object, index, value)
     {
     }
   public:
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     MDefinition *value() const {
         return getOperand(2);
     }
 };
 class MDeleteProperty
   : public MUnaryInstruction,
     public BoxInputsPolicy
 {
     CompilerRootPropertyName name_;
   protected:
     MDeleteProperty(MDefinition *val, PropertyName *name)
       : MUnaryInstruction(val),
         name_(name)
     {
         setResultType(MIRType_Boolean);
     }
   public:
     INSTRUCTION_HEADER(DeleteProperty)
     static MDeleteProperty *New(TempAllocator &alloc, MDefinition *obj, PropertyName *name) {
         return new(alloc) MDeleteProperty(obj, name);
     }
     MDefinition *value() const {
         return getOperand(0);
     }
     PropertyName *name() const {
         return name_;
     }
     virtual TypePolicy *typePolicy() {
         return this;
     }
 };
 class MDeleteElement
   : public MBinaryInstruction,
     public BoxInputsPolicy
 {
     MDeleteElement(MDefinition *value, MDefinition *index)
       : MBinaryInstruction(value, index)
     {
         setResultType(MIRType_Boolean);
     }
   public:
     INSTRUCTION_HEADER(DeleteElement)
     static MDeleteElement *New(TempAllocator &alloc, MDefinition *value, MDefinition *index) {
         return new(alloc) MDeleteElement(value, index);
     }
     MDefinition *value() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     virtual TypePolicy *typePolicy() {
         return this;
     }
 };
 // Note: This uses CallSetElementPolicy to always box its second input,
 // ensuring we don't need two LIR instructions to lower this.
 class MCallSetProperty
   : public MSetPropertyInstruction,
     public CallSetElementPolicy
 {
     MCallSetProperty(MDefinition *obj, MDefinition *value, PropertyName *name, bool strict)
       : MSetPropertyInstruction(obj, value, name, strict)
     {
     }
   public:
     INSTRUCTION_HEADER(CallSetProperty)
     static MCallSetProperty *New(TempAllocator &alloc, MDefinition *obj, MDefinition *value,
                                  PropertyName *name, bool strict)
     {
         return new(alloc) MCallSetProperty(obj, value, name, strict);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MSetPropertyCache
   : public MSetPropertyInstruction,
     public MixPolicy<SingleObjectPolicy, NoFloatPolicy<1> >
 {
     bool needsTypeBarrier_;
     MSetPropertyCache(MDefinition *obj, MDefinition *value, PropertyName *name, bool strict,
                       bool typeBarrier)
       : MSetPropertyInstruction(obj, value, name, strict),
         needsTypeBarrier_(typeBarrier)
     {
     }
   public:
     INSTRUCTION_HEADER(SetPropertyCache)
     static MSetPropertyCache *New(TempAllocator &alloc, MDefinition *obj, MDefinition *value,
                                   PropertyName *name, bool strict, bool typeBarrier)
     {
         return new(alloc) MSetPropertyCache(obj, value, name, strict, typeBarrier);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool needsTypeBarrier() const {
         return needsTypeBarrier_;
     }
 };
 class MSetElementCache
   : public MSetElementInstruction,
     public MixPolicy<ObjectPolicy<0>, BoxPolicy<1> >
 {
     bool strict_;
     bool guardHoles_;
     MSetElementCache(MDefinition *obj, MDefinition *index, MDefinition *value, bool strict,
                      bool guardHoles)
       : MSetElementInstruction(obj, index, value),
         strict_(strict),
         guardHoles_(guardHoles)
     {
     }
   public:
     INSTRUCTION_HEADER(SetElementCache);
     static MSetElementCache *New(TempAllocator &alloc, MDefinition *obj, MDefinition *index,
                                  MDefinition *value, bool strict, bool guardHoles)
     {
         return new(alloc) MSetElementCache(obj, index, value, strict, guardHoles);
     }
     bool strict() const {
         return strict_;
     }
     bool guardHoles() const {
         return guardHoles_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool canConsumeFloat32(MUse *use) const { return use->index() == 2; }
 };
 class MCallGetProperty
   : public MUnaryInstruction,
     public BoxInputsPolicy
 {
     CompilerRootPropertyName name_;
     bool idempotent_;
     bool callprop_;
     MCallGetProperty(MDefinition *value, PropertyName *name, bool callprop)
       : MUnaryInstruction(value), name_(name),
         idempotent_(false),
         callprop_(callprop)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(CallGetProperty)
     static MCallGetProperty *New(TempAllocator &alloc, MDefinition *value, PropertyName *name,
                                  bool callprop)
     {
         return new(alloc) MCallGetProperty(value, name, callprop);
     }
     MDefinition *value() const {
         return getOperand(0);
     }
     PropertyName *name() const {
         return name_;
     }
     bool callprop() const {
         return callprop_;
     }
     TypePolicy *typePolicy() {
         return this;
     }
     // Constructors need to perform a GetProp on the function prototype.
     // Since getters cannot be set on the prototype, fetching is non-effectful.
     // The operation may be safely repeated in case of bailout.
     void setIdempotent() {
         idempotent_ = true;
     }
     AliasSet getAliasSet() const {
         if (!idempotent_)
             return AliasSet::Store(AliasSet::Any);
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Inline call to handle lhs[rhs]. The first input is a Value so that this
 // instruction can handle both objects and strings.
 class MCallGetElement
   : public MBinaryInstruction,
     public BoxInputsPolicy
 {
     MCallGetElement(MDefinition *lhs, MDefinition *rhs)
       : MBinaryInstruction(lhs, rhs)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(CallGetElement)
     static MCallGetElement *New(TempAllocator &alloc, MDefinition *lhs, MDefinition *rhs) {
         return new(alloc) MCallGetElement(lhs, rhs);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MCallSetElement
   : public MSetElementInstruction,
     public CallSetElementPolicy
 {
     MCallSetElement(MDefinition *object, MDefinition *index, MDefinition *value)
       : MSetElementInstruction(object, index, value)
     {
     }
   public:
     INSTRUCTION_HEADER(CallSetElement)
     static MCallSetElement *New(TempAllocator &alloc, MDefinition *object, MDefinition *index,
                                 MDefinition *value)
     {
         return new(alloc) MCallSetElement(object, index, value);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MCallInitElementArray
   : public MAryInstruction<2>,
     public MixPolicy<ObjectPolicy<0>, BoxPolicy<1> >
 {
     uint32_t index_;
     MCallInitElementArray(MDefinition *obj, uint32_t index, MDefinition *val)
       : index_(index)
     {
         setOperand(0, obj);
         setOperand(1, val);
     }
   public:
     INSTRUCTION_HEADER(CallInitElementArray)
     static MCallInitElementArray *New(TempAllocator &alloc, MDefinition *obj, uint32_t index,
                                       MDefinition *val)
     {
         return new(alloc) MCallInitElementArray(obj, index, val);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     uint32_t index() const {
         return index_;
     }
     MDefinition *value() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MSetDOMProperty
   : public MAryInstruction<2>,
     public MixPolicy<ObjectPolicy<0>, BoxPolicy<1> >
 {
     const JSJitSetterOp func_;
     MSetDOMProperty(const JSJitSetterOp func, MDefinition *obj, MDefinition *val)
       : func_(func)
     {
         setOperand(0, obj);
         setOperand(1, val);
     }
   public:
     INSTRUCTION_HEADER(SetDOMProperty)
     static MSetDOMProperty *New(TempAllocator &alloc, const JSJitSetterOp func, MDefinition *obj,
                                 MDefinition *val)
     {
         return new(alloc) MSetDOMProperty(func, obj, val);
     }
     const JSJitSetterOp fun() {
         return func_;
     }
     MDefinition *object() {
         return getOperand(0);
     }
     MDefinition *value()
     {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MGetDOMProperty
   : public MAryInstruction<2>,
     public ObjectPolicy<0>
 {
     const JSJitInfo *info_;
   protected:
     MGetDOMProperty(const JSJitInfo *jitinfo, MDefinition *obj, MDefinition *guard)
       : info_(jitinfo)
     {
         JS_ASSERT(jitinfo);
         JS_ASSERT(jitinfo->type() == JSJitInfo::Getter);
         setOperand(0, obj);
         // Pin the guard as an operand if we want to hoist later
         setOperand(1, guard);
         // We are movable iff the jitinfo says we can be.
         if (isDomMovable()) {
             JS_ASSERT(jitinfo->aliasSet() != JSJitInfo::AliasEverything);
             setMovable();
         } else {
             // If we're not movable, that means we shouldn't be DCEd either,
             // because we might throw an exception when called, and getting rid
             // of that is observable.
             setGuard();
         }
         setResultType(MIRType_Value);
     }
     const JSJitInfo *info() const {
         return info_;
     }
   public:
     INSTRUCTION_HEADER(GetDOMProperty)
     static MGetDOMProperty *New(TempAllocator &alloc, const JSJitInfo *info, MDefinition *obj,
                                 MDefinition *guard)
     {
         return new(alloc) MGetDOMProperty(info, obj, guard);
     }
     const JSJitGetterOp fun() {
         return info_->getter;
     }
     bool isInfallible() const {
         return info_->isInfallible;
     }
     bool isDomMovable() const {
         return info_->isMovable;
     }
     JSJitInfo::AliasSet domAliasSet() const {
         return info_->aliasSet();
     }
     size_t domMemberSlotIndex() const {
         MOZ_ASSERT(info_->isInSlot);
         return info_->slotIndex;
     }
     MDefinition *object() {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!isDomMovable())
             return false;
         if (!ins->isGetDOMProperty())
             return false;
         // Checking the jitinfo is the same as checking the constant function
         if (!(info() == ins->toGetDOMProperty()->info()))
             return false;
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         JSJitInfo::AliasSet aliasSet = domAliasSet();
         if (aliasSet == JSJitInfo::AliasNone)
             return AliasSet::None();
         if (aliasSet == JSJitInfo::AliasDOMSets)
             return AliasSet::Load(AliasSet::DOMProperty);
         JS_ASSERT(aliasSet == JSJitInfo::AliasEverything);
         return AliasSet::Store(AliasSet::Any);
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MGetDOMMember : public MGetDOMProperty
 {
     // We inherit everything from MGetDOMProperty except our possiblyCalls value
     MGetDOMMember(const JSJitInfo *jitinfo, MDefinition *obj, MDefinition *guard)
         : MGetDOMProperty(jitinfo, obj, guard)
     {
     }
   public:
     INSTRUCTION_HEADER(GetDOMMember)
     static MGetDOMMember *New(TempAllocator &alloc, const JSJitInfo *info, MDefinition *obj,
                               MDefinition *guard)
     {
         return new(alloc) MGetDOMMember(info, obj, guard);
     }
     bool possiblyCalls() const {
         return false;
     }
 };
 class MStringLength
   : public MUnaryInstruction,
     public StringPolicy<0>
 {
     MStringLength(MDefinition *string)
       : MUnaryInstruction(string)
     {
         setResultType(MIRType_Int32);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(StringLength)
     static MStringLength *New(TempAllocator &alloc, MDefinition *string) {
         return new(alloc) MStringLength(string);
     }
     MDefinition *foldsTo(TempAllocator &alloc, bool useValueNumbers);
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *string() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         // The string |length| property is immutable, so there is no
         // implicit dependency.
         return AliasSet::None();
     }
     void computeRange(TempAllocator &alloc);
 };
 // Inlined version of Math.floor().
 class MFloor
   : public MUnaryInstruction,
     public FloatingPointPolicy<0>
 {
     MFloor(MDefinition *num)
       : MUnaryInstruction(num)
     {
         setResultType(MIRType_Int32);
         setPolicyType(MIRType_Double);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Floor)
     static MFloor *New(TempAllocator &alloc, MDefinition *num) {
         return new(alloc) MFloor(num);
     }
     MDefinition *num() const {
         return getOperand(0);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool isFloat32Commutative() const {
         return true;
     }
     void trySpecializeFloat32(TempAllocator &alloc);
 #ifdef DEBUG
     bool isConsistentFloat32Use(MUse *use) const {
         return true;
     }
 #endif
 };
 // Inlined version of Math.round().
 class MRound
   : public MUnaryInstruction,
     public FloatingPointPolicy<0>
 {
     MRound(MDefinition *num)
       : MUnaryInstruction(num)
     {
         setResultType(MIRType_Int32);
         setPolicyType(MIRType_Double);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(Round)
     static MRound *New(TempAllocator &alloc, MDefinition *num) {
         return new(alloc) MRound(num);
     }
     MDefinition *num() const {
         return getOperand(0);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool isFloat32Commutative() const {
         return true;
     }
     void trySpecializeFloat32(TempAllocator &alloc);
 #ifdef DEBUG
     bool isConsistentFloat32Use(MUse *use) const {
         return true;
     }
 #endif
 };
 class MIteratorStart
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     uint8_t flags_;
     MIteratorStart(MDefinition *obj, uint8_t flags)
       : MUnaryInstruction(obj), flags_(flags)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(IteratorStart)
     static MIteratorStart *New(TempAllocator &alloc, MDefinition *obj, uint8_t flags) {
         return new(alloc) MIteratorStart(obj, flags);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     uint8_t flags() const {
         return flags_;
     }
 };
 class MIteratorNext
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MIteratorNext(MDefinition *iter)
       : MUnaryInstruction(iter)
     {
         setResultType(MIRType_Value);
     }
   public:
     INSTRUCTION_HEADER(IteratorNext)
     static MIteratorNext *New(TempAllocator &alloc, MDefinition *iter) {
         return new(alloc) MIteratorNext(iter);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *iterator() const {
         return getOperand(0);
     }
 };
 class MIteratorMore
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MIteratorMore(MDefinition *iter)
       : MUnaryInstruction(iter)
     {
         setResultType(MIRType_Boolean);
     }
   public:
     INSTRUCTION_HEADER(IteratorMore)
     static MIteratorMore *New(TempAllocator &alloc, MDefinition *iter) {
         return new(alloc) MIteratorMore(iter);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *iterator() const {
         return getOperand(0);
     }
 };
 class MIteratorEnd
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MIteratorEnd(MDefinition *iter)
       : MUnaryInstruction(iter)
     { }
   public:
     INSTRUCTION_HEADER(IteratorEnd)
     static MIteratorEnd *New(TempAllocator &alloc, MDefinition *iter) {
         return new(alloc) MIteratorEnd(iter);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *iterator() const {
         return getOperand(0);
     }
 };
 // Implementation for 'in' operator.
 class MIn
   : public MBinaryInstruction,
     public MixPolicy<BoxPolicy<0>, ObjectPolicy<1> >
 {
     MIn(MDefinition *key, MDefinition *obj)
       : MBinaryInstruction(key, obj)
     {
         setResultType(MIRType_Boolean);
     }
   public:
     INSTRUCTION_HEADER(In)
     static MIn *New(TempAllocator &alloc, MDefinition *key, MDefinition *obj) {
         return new(alloc) MIn(key, obj);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Test whether the index is in the array bounds or a hole.
 class MInArray
   : public MQuaternaryInstruction,
     public ObjectPolicy<3>
 {
     bool needsHoleCheck_;
     bool needsNegativeIntCheck_;
     MInArray(MDefinition *elements, MDefinition *index,
              MDefinition *initLength, MDefinition *object,
              bool needsHoleCheck)
       : MQuaternaryInstruction(elements, index, initLength, object),
         needsHoleCheck_(needsHoleCheck),
         needsNegativeIntCheck_(true)
     {
         setResultType(MIRType_Boolean);
         setMovable();
         JS_ASSERT(elements->type() == MIRType_Elements);
         JS_ASSERT(index->type() == MIRType_Int32);
         JS_ASSERT(initLength->type() == MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(InArray)
     static MInArray *New(TempAllocator &alloc, MDefinition *elements, MDefinition *index,
                          MDefinition *initLength, MDefinition *object,
                          bool needsHoleCheck)
     {
         return new(alloc) MInArray(elements, index, initLength, object, needsHoleCheck);
     }
     MDefinition *elements() const {
         return getOperand(0);
     }
     MDefinition *index() const {
         return getOperand(1);
     }
     MDefinition *initLength() const {
         return getOperand(2);
     }
     MDefinition *object() const {
         return getOperand(3);
     }
     bool needsHoleCheck() const {
         return needsHoleCheck_;
     }
     bool needsNegativeIntCheck() const {
         return needsNegativeIntCheck_;
     }
     void collectRangeInfoPreTrunc();
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::Element);
     }
     bool congruentTo(const MDefinition *ins) const {
         if (!ins->isInArray())
             return false;
         const MInArray *other = ins->toInArray();
         if (needsHoleCheck() != other->needsHoleCheck())
             return false;
         if (needsNegativeIntCheck() != other->needsNegativeIntCheck())
             return false;
         return congruentIfOperandsEqual(other);
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 // Implementation for instanceof operator with specific rhs.
 class MInstanceOf
   : public MUnaryInstruction,
     public InstanceOfPolicy
 {
     CompilerRootObject protoObj_;
     MInstanceOf(MDefinition *obj, JSObject *proto)
       : MUnaryInstruction(obj),
         protoObj_(proto)
     {
         setResultType(MIRType_Boolean);
     }
   public:
     INSTRUCTION_HEADER(InstanceOf)
     static MInstanceOf *New(TempAllocator &alloc, MDefinition *obj, JSObject *proto) {
         return new(alloc) MInstanceOf(obj, proto);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     JSObject *prototypeObject() {
         return protoObj_;
     }
 };
 // Implementation for instanceof operator with unknown rhs.
 class MCallInstanceOf
   : public MBinaryInstruction,
     public MixPolicy<BoxPolicy<0>, ObjectPolicy<1> >
 {
     MCallInstanceOf(MDefinition *obj, MDefinition *proto)
       : MBinaryInstruction(obj, proto)
     {
         setResultType(MIRType_Boolean);
     }
   public:
     INSTRUCTION_HEADER(CallInstanceOf)
     static MCallInstanceOf *New(TempAllocator &alloc, MDefinition *obj, MDefinition *proto) {
         return new(alloc) MCallInstanceOf(obj, proto);
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MArgumentsLength : public MNullaryInstruction
 {
     MArgumentsLength()
     {
         setResultType(MIRType_Int32);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(ArgumentsLength)
     static MArgumentsLength *New(TempAllocator &alloc) {
         return new(alloc) MArgumentsLength();
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         // Arguments |length| cannot be mutated by Ion Code.
         return AliasSet::None();
    }
     void computeRange(TempAllocator &alloc);
 };
 // This MIR instruction is used to get an argument from the actual arguments.
 class MGetFrameArgument
   : public MUnaryInstruction,
     public IntPolicy<0>
 {
     bool scriptHasSetArg_;
     MGetFrameArgument(MDefinition *idx, bool scriptHasSetArg)
       : MUnaryInstruction(idx),
         scriptHasSetArg_(scriptHasSetArg)
     {
         setResultType(MIRType_Value);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(GetFrameArgument)
     static MGetFrameArgument *New(TempAllocator &alloc, MDefinition *idx, bool scriptHasSetArg) {
         return new(alloc) MGetFrameArgument(idx, scriptHasSetArg);
     }
     MDefinition *index() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         // If the script doesn't have any JSOP_SETARG ops, then this instruction is never
         // aliased.
         if (scriptHasSetArg_)
             return AliasSet::Load(AliasSet::FrameArgument);
         return AliasSet::None();
     }
 };
 // This MIR instruction is used to set an argument value in the frame.
 class MSetFrameArgument
   : public MUnaryInstruction,
     public NoFloatPolicy<0>
 {
     uint32_t argno_;
     MSetFrameArgument(uint32_t argno, MDefinition *value)
       : MUnaryInstruction(value),
         argno_(argno)
     {
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(SetFrameArgument)
     static MSetFrameArgument *New(TempAllocator &alloc, uint32_t argno, MDefinition *value) {
         return new(alloc) MSetFrameArgument(argno, value);
     }
     uint32_t argno() const {
         return argno_;
     }
     MDefinition *value() const {
         return getOperand(0);
     }
     bool congruentTo(const MDefinition *ins) const {
         return false;
     }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::FrameArgument);
     }
     TypePolicy *typePolicy() {
         return this;
     }
 };
 class MRestCommon
 {
     unsigned numFormals_;
     CompilerRootObject templateObject_;
   protected:
     MRestCommon(unsigned numFormals, JSObject *templateObject)
       : numFormals_(numFormals),
         templateObject_(templateObject)
    { }
   public:
     unsigned numFormals() const {
         return numFormals_;
     }
     JSObject *templateObject() const {
         return templateObject_;
     }
 };
 class MRest
   : public MUnaryInstruction,
     public MRestCommon,
     public IntPolicy<0>
 {
     MRest(types::CompilerConstraintList *constraints, MDefinition *numActuals, unsigned numFormals,
           JSObject *templateObject)
       : MUnaryInstruction(numActuals),
         MRestCommon(numFormals, templateObject)
     {
         setResultType(MIRType_Object);
         setResultTypeSet(MakeSingletonTypeSet(constraints, templateObject));
     }
   public:
     INSTRUCTION_HEADER(Rest);
     static MRest *New(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                       MDefinition *numActuals, unsigned numFormals,
                       JSObject *templateObject)
     {
         return new(alloc) MRest(constraints, numActuals, numFormals, templateObject);
     }
     MDefinition *numActuals() const {
         return getOperand(0);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MRestPar
   : public MBinaryInstruction,
     public MRestCommon,
     public IntPolicy<1>
 {
     MRestPar(MDefinition *cx, MDefinition *numActuals, unsigned numFormals,
              JSObject *templateObject, types::TemporaryTypeSet *resultTypes)
       : MBinaryInstruction(cx, numActuals),
         MRestCommon(numFormals, templateObject)
     {
         setResultType(MIRType_Object);
         setResultTypeSet(resultTypes);
     }
   public:
     INSTRUCTION_HEADER(RestPar);
     static MRestPar *New(TempAllocator &alloc, MDefinition *cx, MRest *rest) {
         return new(alloc) MRestPar(cx, rest->numActuals(), rest->numFormals(),
                                    rest->templateObject(), rest->resultTypeSet());
     }
     MDefinition *forkJoinContext() const {
         return getOperand(0);
     }
     MDefinition *numActuals() const {
         return getOperand(1);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // Guard on an object being safe for writes by current parallel cx.
 // Must be either thread-local or else a handle into the destination array.
 class MGuardThreadExclusive
   : public MBinaryInstruction,
     public ObjectPolicy<1>
 {
     MGuardThreadExclusive(MDefinition *cx, MDefinition *obj)
       : MBinaryInstruction(cx, obj)
     {
         setResultType(MIRType_None);
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(GuardThreadExclusive);
     static MGuardThreadExclusive *New(TempAllocator &alloc, MDefinition *cx, MDefinition *obj) {
         return new(alloc) MGuardThreadExclusive(cx, obj);
     }
     MDefinition *forkJoinContext() const {
         return getOperand(0);
     }
     MDefinition *object() const {
         return getOperand(1);
     }
     BailoutKind bailoutKind() const {
         return Bailout_Normal;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MFilterTypeSet
   : public MUnaryInstruction,
     public FilterTypeSetPolicy
 {
     MFilterTypeSet(MDefinition *def, types::TemporaryTypeSet *types)
       : MUnaryInstruction(def)
     {
         JS_ASSERT(!types->unknown());
         setResultType(types->getKnownMIRType());
         setResultTypeSet(types);
     }
   public:
     INSTRUCTION_HEADER(FilterTypeSet)
     static MFilterTypeSet *New(TempAllocator &alloc, MDefinition *def, types::TemporaryTypeSet *types) {
         return new(alloc) MFilterTypeSet(def, types);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *def) const {
         return false;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     virtual bool neverHoist() const {
         return resultTypeSet()->empty();
     }
 };
 // Given a value, guard that the value is in a particular TypeSet, then returns
 // that value.
 class MTypeBarrier
   : public MUnaryInstruction,
     public TypeBarrierPolicy
 {
     MTypeBarrier(MDefinition *def, types::TemporaryTypeSet *types)
       : MUnaryInstruction(def)
     {
         JS_ASSERT(!types->unknown());
         setResultType(types->getKnownMIRType());
         setResultTypeSet(types);
         setGuard();
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(TypeBarrier)
     static MTypeBarrier *New(TempAllocator &alloc, MDefinition *def, types::TemporaryTypeSet *types) {
         return new(alloc) MTypeBarrier(def, types);
     }
     void printOpcode(FILE *fp) const;
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *def) const {
         return false;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     virtual bool neverHoist() const {
         return resultTypeSet()->empty();
     }
     bool alwaysBails() const {
         // If mirtype of input doesn't agree with mirtype of barrier,
         // we will definitely bail.
         MIRType type = resultTypeSet()->getKnownMIRType();
         if (type == MIRType_Value)
             return false;
         if (input()->type() == MIRType_Value)
             return false;
         return input()->type() != type;
     }
 };
 // Like MTypeBarrier, guard that the value is in the given type set. This is
 // used before property writes to ensure the value being written is represented
 // in the property types for the object.
 class MMonitorTypes : public MUnaryInstruction, public BoxInputsPolicy
 {
     const types::TemporaryTypeSet *typeSet_;
     MMonitorTypes(MDefinition *def, const types::TemporaryTypeSet *types)
       : MUnaryInstruction(def),
         typeSet_(types)
     {
         setGuard();
         JS_ASSERT(!types->unknown());
     }
   public:
     INSTRUCTION_HEADER(MonitorTypes)
     static MMonitorTypes *New(TempAllocator &alloc, MDefinition *def, const types::TemporaryTypeSet *types) {
         return new(alloc) MMonitorTypes(def, types);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     const types::TemporaryTypeSet *typeSet() const {
         return typeSet_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // Given a value being written to another object, update the generational store
 // buffer if the value is in the nursery and object is in the tenured heap.
 class MPostWriteBarrier : public MBinaryInstruction, public ObjectPolicy<0>
 {
     MPostWriteBarrier(MDefinition *obj, MDefinition *value)
       : MBinaryInstruction(obj, value)
     {
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(PostWriteBarrier)
     static MPostWriteBarrier *New(TempAllocator &alloc, MDefinition *obj, MDefinition *value) {
         return new(alloc) MPostWriteBarrier(obj, value);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     MDefinition *value() const {
         return getOperand(1);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 #ifdef DEBUG
     bool isConsistentFloat32Use(MUse *use) const {
         // During lowering, values that neither have object nor value MIR type
         // are ignored, thus Float32 can show up at this point without any issue.
         return use->index() == 1;
     }
 #endif
 };
 class MNewSlots : public MNullaryInstruction
 {
     unsigned nslots_;
     MNewSlots(unsigned nslots)
       : nslots_(nslots)
     {
         setResultType(MIRType_Slots);
     }
   public:
     INSTRUCTION_HEADER(NewSlots)
     static MNewSlots *New(TempAllocator &alloc, unsigned nslots) {
         return new(alloc) MNewSlots(nslots);
     }
     unsigned nslots() const {
         return nslots_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 class MNewDeclEnvObject : public MNullaryInstruction
 {
     CompilerRootObject templateObj_;
     MNewDeclEnvObject(JSObject *templateObj)
       : MNullaryInstruction(),
         templateObj_(templateObj)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(NewDeclEnvObject);
     static MNewDeclEnvObject *New(TempAllocator &alloc, JSObject *templateObj) {
         return new(alloc) MNewDeclEnvObject(templateObj);
     }
     JSObject *templateObj() {
         return templateObj_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MNewCallObjectBase : public MUnaryInstruction
 {
     CompilerRootObject templateObj_;
   protected:
     MNewCallObjectBase(JSObject *templateObj, MDefinition *slots)
       : MUnaryInstruction(slots),
         templateObj_(templateObj)
     {
         setResultType(MIRType_Object);
     }
   public:
     MDefinition *slots() {
         return getOperand(0);
     }
     JSObject *templateObject() {
         return templateObj_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MNewCallObject : public MNewCallObjectBase
 {
   public:
     INSTRUCTION_HEADER(NewCallObject)
     MNewCallObject(JSObject *templateObj, MDefinition *slots)
       : MNewCallObjectBase(templateObj, slots)
     {}
     static MNewCallObject *
     New(TempAllocator &alloc, JSObject *templateObj, MDefinition *slots)
     {
         return new(alloc) MNewCallObject(templateObj, slots);
     }
 };
 class MNewRunOnceCallObject : public MNewCallObjectBase
 {
   public:
     INSTRUCTION_HEADER(NewRunOnceCallObject)
     MNewRunOnceCallObject(JSObject *templateObj, MDefinition *slots)
       : MNewCallObjectBase(templateObj, slots)
     {}
     static MNewRunOnceCallObject *
     New(TempAllocator &alloc, JSObject *templateObj, MDefinition *slots)
     {
         return new(alloc) MNewRunOnceCallObject(templateObj, slots);
     }
 };
 class MNewCallObjectPar : public MBinaryInstruction
 {
     CompilerRootObject templateObj_;
     MNewCallObjectPar(MDefinition *cx, JSObject *templateObj, MDefinition *slots)
         : MBinaryInstruction(cx, slots),
           templateObj_(templateObj)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(NewCallObjectPar);
     static MNewCallObjectPar *New(TempAllocator &alloc, MDefinition *cx, MNewCallObjectBase *callObj) {
         return new(alloc) MNewCallObjectPar(cx, callObj->templateObject(), callObj->slots());
     }
     MDefinition *forkJoinContext() const {
         return getOperand(0);
     }
     MDefinition *slots() const {
         return getOperand(1);
     }
     JSObject *templateObj() const {
         return templateObj_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MNewStringObject :
   public MUnaryInstruction,
   public ConvertToStringPolicy<0>
 {
     CompilerRootObject templateObj_;
     MNewStringObject(MDefinition *input, JSObject *templateObj)
       : MUnaryInstruction(input),
         templateObj_(templateObj)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(NewStringObject)
     static MNewStringObject *New(TempAllocator &alloc, MDefinition *input, JSObject *templateObj) {
         return new(alloc) MNewStringObject(input, templateObj);
     }
     StringObject *templateObj() const;
     TypePolicy *typePolicy() {
         return this;
     }
 };
 // Node that represents that a script has begun executing. This comes at the
 // start of the function and is called once per function (including inline
 // ones)
 class MProfilerStackOp : public MNullaryInstruction
 {
   public:
     enum Type {
         Enter,        // a function has begun executing and it is not inline
         Exit,         // any function has exited (inlined or normal)
         InlineEnter,  // an inline function has begun executing
         InlineExit    // all instructions of an inline function are done, a
                       // return from the inline function could have occurred
                       // before this boundary
     };
   private:
     JSScript *script_;
     Type type_;
     unsigned inlineLevel_;
     MProfilerStackOp(JSScript *script, Type type, unsigned inlineLevel)
       : script_(script), type_(type), inlineLevel_(inlineLevel)
     {
         JS_ASSERT_IF(type != InlineExit, script != nullptr);
         JS_ASSERT_IF(type == InlineEnter, inlineLevel != 0);
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(ProfilerStackOp)
     static MProfilerStackOp *New(TempAllocator &alloc, JSScript *script, Type type,
                                   unsigned inlineLevel = 0) {
         return new(alloc) MProfilerStackOp(script, type, inlineLevel);
     }
     JSScript *script() {
         return script_;
     }
     Type type() {
         return type_;
     }
     unsigned inlineLevel() {
         return inlineLevel_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // This is an alias for MLoadFixedSlot.
 class MEnclosingScope : public MLoadFixedSlot
 {
     MEnclosingScope(MDefinition *obj)
       : MLoadFixedSlot(obj, ScopeObject::enclosingScopeSlot())
     {
         setResultType(MIRType_Object);
     }
   public:
     static MEnclosingScope *New(TempAllocator &alloc, MDefinition *obj) {
         return new(alloc) MEnclosingScope(obj);
     }
     AliasSet getAliasSet() const {
         // ScopeObject reserved slots are immutable.
         return AliasSet::None();
     }
 };
 // Creates a dense array of the given length.
 //
 // Note: the template object should be an *empty* dense array!
 class MNewDenseArrayPar : public MBinaryInstruction
 {
     CompilerRootObject templateObject_;
     MNewDenseArrayPar(MDefinition *cx, MDefinition *length, JSObject *templateObject)
       : MBinaryInstruction(cx, length),
         templateObject_(templateObject)
     {
         setResultType(MIRType_Object);
     }
   public:
     INSTRUCTION_HEADER(NewDenseArrayPar);
     static MNewDenseArrayPar *New(TempAllocator &alloc, MDefinition *cx, MDefinition *length,
                                   JSObject *templateObject)
     {
         return new(alloc) MNewDenseArrayPar(cx, length, templateObject);
     }
     MDefinition *forkJoinContext() const {
         return getOperand(0);
     }
     MDefinition *length() const {
         return getOperand(1);
     }
     JSObject *templateObject() const {
         return templateObject_;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 // A resume point contains the information needed to reconstruct the Baseline
 // state from a position in the JIT. See the big comment near resumeAfter() in
 // IonBuilder.cpp.
 class MResumePoint MOZ_FINAL : public MNode, public InlineForwardListNode<MResumePoint>
 {
   public:
     enum Mode {
         ResumeAt,    // Resume until before the current instruction
         ResumeAfter, // Resume after the current instruction
         Outer        // State before inlining.
     };
   private:
     friend class MBasicBlock;
     friend void AssertBasicGraphCoherency(MIRGraph &graph);
     FixedList<MUse> operands_;
     uint32_t stackDepth_;
     jsbytecode *pc_;
     MResumePoint *caller_;
     MInstruction *instruction_;
     Mode mode_;
     MResumePoint(MBasicBlock *block, jsbytecode *pc, MResumePoint *parent, Mode mode);
     void inherit(MBasicBlock *state);
   protected:
     // Initializes operands_ to an empty array of a fixed length.
     // The array may then be filled in by inherit().
     bool init(TempAllocator &alloc) {
         return operands_.init(alloc, stackDepth_);
     }
     // Overwrites an operand without updating its Uses.
     void setOperand(size_t index, MDefinition *operand) {
         JS_ASSERT(index < stackDepth_);
         operands_[index].set(operand, this, index);
         operand->addUse(&operands_[index]);
     }
     void clearOperand(size_t index) {
         JS_ASSERT(index < stackDepth_);
         operands_[index].set(nullptr, this, index);
     }
     MUse *getUseFor(size_t index) {
         return &operands_[index];
     }
   public:
     static MResumePoint *New(TempAllocator &alloc, MBasicBlock *block, jsbytecode *pc,
                              MResumePoint *parent, Mode mode);
     MNode::Kind kind() const {
         return MNode::ResumePoint;
     }
     size_t numOperands() const {
         return stackDepth_;
     }
     MDefinition *getOperand(size_t index) const {
         JS_ASSERT(index < stackDepth_);
         return operands_[index].producer();
     }
     jsbytecode *pc() const {
         return pc_;
     }
     uint32_t stackDepth() const {
         return stackDepth_;
     }
     MResumePoint *caller() {
         return caller_;
     }
     void setCaller(MResumePoint *caller) {
         caller_ = caller;
     }
     uint32_t frameCount() const {
         uint32_t count = 1;
         for (MResumePoint *it = caller_; it; it = it->caller_)
             count++;
         return count;
     }
     MInstruction *instruction() {
         return instruction_;
     }
     void setInstruction(MInstruction *ins) {
         instruction_ = ins;
     }
     Mode mode() const {
         return mode_;
     }
     void discardUses() {
         for (size_t i = 0; i < stackDepth_; i++) {
             if (operands_[i].hasProducer())
                 operands_[i].producer()->removeUse(&operands_[i]);
         }
     }
     bool writeRecoverData(CompactBufferWriter &writer) const;
 };
 class MIsCallable
   : public MUnaryInstruction,
     public SingleObjectPolicy
 {
     MIsCallable(MDefinition *object)
       : MUnaryInstruction(object)
     {
         setResultType(MIRType_Boolean);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(IsCallable);
     static MIsCallable *New(TempAllocator &alloc, MDefinition *obj) {
         return new(alloc) MIsCallable(obj);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MHaveSameClass
   : public MBinaryInstruction,
     public MixPolicy<ObjectPolicy<0>, ObjectPolicy<1> >
 {
     MHaveSameClass(MDefinition *left, MDefinition *right)
       : MBinaryInstruction(left, right)
     {
         setResultType(MIRType_Boolean);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(HaveSameClass);
     static MHaveSameClass *New(TempAllocator &alloc, MDefinition *left, MDefinition *right) {
         return new(alloc) MHaveSameClass(left, right);
     }
     TypePolicy *typePolicy() {
         return this;
     }
     bool congruentTo(const MDefinition *ins) const {
         return congruentIfOperandsEqual(ins);
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MHasClass
     : public MUnaryInstruction,
       public SingleObjectPolicy
 {
     const Class *class_;
     MHasClass(MDefinition *object, const Class *clasp)
       : MUnaryInstruction(object)
       , class_(clasp)
     {
         JS_ASSERT(object->type() == MIRType_Object);
         setResultType(MIRType_Boolean);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(HasClass);
     static MHasClass *New(TempAllocator &alloc, MDefinition *obj, const Class *clasp) {
         return new(alloc) MHasClass(obj, clasp);
     }
     MDefinition *object() const {
         return getOperand(0);
     }
     const Class *getClass() const {
         return class_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 // Increase the usecount of the provided script upon execution and test if
 // the usecount surpasses the threshold. Upon hit it will recompile the
 // outermost script (i.e. not the inlined script).
 class MRecompileCheck : public MNullaryInstruction
 {
     JSScript *script_;
     uint32_t recompileThreshold_;
     MRecompileCheck(JSScript *script, uint32_t recompileThreshold)
       : script_(script),
         recompileThreshold_(recompileThreshold)
     {
         setGuard();
     }
   public:
     INSTRUCTION_HEADER(RecompileCheck);
     static MRecompileCheck *New(TempAllocator &alloc, JSScript *script_, uint32_t useCount) {
         return new(alloc) MRecompileCheck(script_, useCount);
     }
     JSScript *script() const {
         return script_;
     }
     uint32_t recompileThreshold() const {
         return recompileThreshold_;
     }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }
 };
 class MAsmJSNeg : public MUnaryInstruction
 {
     MAsmJSNeg(MDefinition *op, MIRType type)
       : MUnaryInstruction(op)
     {
         setResultType(type);
         setMovable();
     }
   public:
     INSTRUCTION_HEADER(AsmJSNeg);
     static MAsmJSNeg *NewAsmJS(TempAllocator &alloc, MDefinition *op, MIRType type) {
         return new(alloc) MAsmJSNeg(op, type);
     }
 };
 class MAsmJSHeapAccess
 {
     ArrayBufferView::ViewType viewType_;
     bool skipBoundsCheck_;
   public:
     MAsmJSHeapAccess(ArrayBufferView::ViewType vt, bool s)
       : viewType_(vt), skipBoundsCheck_(s)
     {}
     ArrayBufferView::ViewType viewType() const { return viewType_; }
     bool skipBoundsCheck() const { return skipBoundsCheck_; }
     void setSkipBoundsCheck(bool v) { skipBoundsCheck_ = v; }
 };
 class MAsmJSLoadHeap : public MUnaryInstruction, public MAsmJSHeapAccess
 {
     MAsmJSLoadHeap(ArrayBufferView::ViewType vt, MDefinition *ptr)
       : MUnaryInstruction(ptr), MAsmJSHeapAccess(vt, false)
     {
         setMovable();
         if (vt == ArrayBufferView::TYPE_FLOAT32)
             setResultType(MIRType_Float32);
         else if (vt == ArrayBufferView::TYPE_FLOAT64)
             setResultType(MIRType_Double);
         else
             setResultType(MIRType_Int32);
     }
   public:
     INSTRUCTION_HEADER(AsmJSLoadHeap);
     static MAsmJSLoadHeap *New(TempAllocator &alloc, ArrayBufferView::ViewType vt, MDefinition *ptr) {
         return new(alloc) MAsmJSLoadHeap(vt, ptr);
     }
     MDefinition *ptr() const { return getOperand(0); }
     bool congruentTo(const MDefinition *ins) const;
     AliasSet getAliasSet() const {
         return AliasSet::Load(AliasSet::AsmJSHeap);
     }
     bool mightAlias(const MDefinition *def) const;
 };
 class MAsmJSStoreHeap : public MBinaryInstruction, public MAsmJSHeapAccess
 {
     MAsmJSStoreHeap(ArrayBufferView::ViewType vt, MDefinition *ptr, MDefinition *v)
       : MBinaryInstruction(ptr, v) , MAsmJSHeapAccess(vt, false)
     {}
   public:
     INSTRUCTION_HEADER(AsmJSStoreHeap);
     static MAsmJSStoreHeap *New(TempAllocator &alloc, ArrayBufferView::ViewType vt,
                                 MDefinition *ptr, MDefinition *v)
     {
         return new(alloc) MAsmJSStoreHeap(vt, ptr, v);
     }
     MDefinition *ptr() const { return getOperand(0); }
     MDefinition *value() const { return getOperand(1); }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::AsmJSHeap);
     }
 };
 class MAsmJSLoadGlobalVar : public MNullaryInstruction
 {
     MAsmJSLoadGlobalVar(MIRType type, unsigned globalDataOffset, bool isConstant)
       : globalDataOffset_(globalDataOffset), isConstant_(isConstant)
     {
         JS_ASSERT(IsNumberType(type));
         setResultType(type);
         setMovable();
     }
     unsigned globalDataOffset_;
     bool isConstant_;
   public:
     INSTRUCTION_HEADER(AsmJSLoadGlobalVar);
     static MAsmJSLoadGlobalVar *New(TempAllocator &alloc, MIRType type, unsigned globalDataOffset,
                                     bool isConstant)
     {
         return new(alloc) MAsmJSLoadGlobalVar(type, globalDataOffset, isConstant);
     }
     unsigned globalDataOffset() const { return globalDataOffset_; }
     bool congruentTo(const MDefinition *ins) const;
     AliasSet getAliasSet() const {
         return isConstant_ ? AliasSet::None() : AliasSet::Load(AliasSet::AsmJSGlobalVar);
     }
     bool mightAlias(const MDefinition *def) const;
 };
 class MAsmJSStoreGlobalVar : public MUnaryInstruction
 {
     MAsmJSStoreGlobalVar(unsigned globalDataOffset, MDefinition *v)
       : MUnaryInstruction(v), globalDataOffset_(globalDataOffset)
     {}
     unsigned globalDataOffset_;
   public:
     INSTRUCTION_HEADER(AsmJSStoreGlobalVar);
     static MAsmJSStoreGlobalVar *New(TempAllocator &alloc, unsigned globalDataOffset, MDefinition *v) {
         return new(alloc) MAsmJSStoreGlobalVar(globalDataOffset, v);
     }
     unsigned globalDataOffset() const { return globalDataOffset_; }
     MDefinition *value() const { return getOperand(0); }
     AliasSet getAliasSet() const {
         return AliasSet::Store(AliasSet::AsmJSGlobalVar);
     }
 };
 class MAsmJSLoadFuncPtr : public MUnaryInstruction
 {
     MAsmJSLoadFuncPtr(unsigned globalDataOffset, MDefinition *index)
       : MUnaryInstruction(index), globalDataOffset_(globalDataOffset)
     {
         setResultType(MIRType_Pointer);
     }
     unsigned globalDataOffset_;
   public:
     INSTRUCTION_HEADER(AsmJSLoadFuncPtr);
     static MAsmJSLoadFuncPtr *New(TempAllocator &alloc, unsigned globalDataOffset,
                                   MDefinition *index)
     {
         return new(alloc) MAsmJSLoadFuncPtr(globalDataOffset, index);
     }
     unsigned globalDataOffset() const { return globalDataOffset_; }
     MDefinition *index() const { return getOperand(0); }
 };
 class MAsmJSLoadFFIFunc : public MNullaryInstruction
 {
     MAsmJSLoadFFIFunc(unsigned globalDataOffset)
       : globalDataOffset_(globalDataOffset)
     {
         setResultType(MIRType_Pointer);
     }
     unsigned globalDataOffset_;
   public:
     INSTRUCTION_HEADER(AsmJSLoadFFIFunc);
     static MAsmJSLoadFFIFunc *New(TempAllocator &alloc, unsigned globalDataOffset)
     {
         return new(alloc) MAsmJSLoadFFIFunc(globalDataOffset);
     }
     unsigned globalDataOffset() const { return globalDataOffset_; }
 };
 class MAsmJSParameter : public MNullaryInstruction
 {
     ABIArg abi_;
     MAsmJSParameter(ABIArg abi, MIRType mirType)
       : abi_(abi)
     {
         setResultType(mirType);
     }
   public:
     INSTRUCTION_HEADER(AsmJSParameter);
     static MAsmJSParameter *New(TempAllocator &alloc, ABIArg abi, MIRType mirType) {
         return new(alloc) MAsmJSParameter(abi, mirType);
     }
     ABIArg abi() const { return abi_; }
 };
 class MAsmJSReturn : public MAryControlInstruction<1, 0>
 {
     MAsmJSReturn(MDefinition *ins) {
         setOperand(0, ins);
     }
   public:
     INSTRUCTION_HEADER(AsmJSReturn);
     static MAsmJSReturn *New(TempAllocator &alloc, MDefinition *ins) {
         return new(alloc) MAsmJSReturn(ins);
     }
 };
 class MAsmJSVoidReturn : public MAryControlInstruction<0, 0>
 {
   public:
     INSTRUCTION_HEADER(AsmJSVoidReturn);
     static MAsmJSVoidReturn *New(TempAllocator &alloc) {
         return new(alloc) MAsmJSVoidReturn();
     }
 };
 class MAsmJSPassStackArg : public MUnaryInstruction
 {
     MAsmJSPassStackArg(uint32_t spOffset, MDefinition *ins)
       : MUnaryInstruction(ins),
         spOffset_(spOffset)
     {}
     uint32_t spOffset_;
   public:
     INSTRUCTION_HEADER(AsmJSPassStackArg);
     static MAsmJSPassStackArg *New(TempAllocator &alloc, uint32_t spOffset, MDefinition *ins) {
         return new(alloc) MAsmJSPassStackArg(spOffset, ins);
     }
     uint32_t spOffset() const {
         return spOffset_;
     }
     void incrementOffset(uint32_t inc) {
         spOffset_ += inc;
     }
     MDefinition *arg() const {
         return getOperand(0);
     }
 };
 class MAsmJSCall MOZ_FINAL : public MInstruction
 {
   public:
     class Callee {
       public:
         enum Which { Internal, Dynamic, Builtin };
       private:
         Which which_;
         union {
             Label *internal_;
             MDefinition *dynamic_;
             AsmJSImmKind builtin_;
         } u;
       public:
         Callee() {}
         Callee(Label *callee) : which_(Internal) { u.internal_ = callee; }
         Callee(MDefinition *callee) : which_(Dynamic) { u.dynamic_ = callee; }
         Callee(AsmJSImmKind callee) : which_(Builtin) { u.builtin_ = callee; }
         Which which() const { return which_; }
         Label *internal() const { JS_ASSERT(which_ == Internal); return u.internal_; }
         MDefinition *dynamic() const { JS_ASSERT(which_ == Dynamic); return u.dynamic_; }
         AsmJSImmKind builtin() const { JS_ASSERT(which_ == Builtin); return u.builtin_; }
     };
   private:
     struct Operand {
         AnyRegister reg;
         MUse use;
     };
     CallSiteDesc desc_;
     Callee callee_;
     FixedList<MUse> operands_;
     FixedList<AnyRegister> argRegs_;
     size_t spIncrement_;
     MAsmJSCall(const CallSiteDesc &desc, Callee callee, size_t spIncrement)
      : desc_(desc), callee_(callee), spIncrement_(spIncrement)
     { }
   protected:
     void setOperand(size_t index, MDefinition *operand) {
         operands_[index].set(operand, this, index);
         operand->addUse(&operands_[index]);
     }
     MUse *getUseFor(size_t index) {
         return &operands_[index];
     }
   public:
     INSTRUCTION_HEADER(AsmJSCall);
     struct Arg {
         AnyRegister reg;
         MDefinition *def;
         Arg(AnyRegister reg, MDefinition *def) : reg(reg), def(def) {}
     };
     typedef Vector<Arg, 8> Args;
     static MAsmJSCall *New(TempAllocator &alloc, const CallSiteDesc &desc, Callee callee,
                            const Args &args, MIRType resultType, size_t spIncrement);
     size_t numOperands() const {
         return operands_.length();
     }
     MDefinition *getOperand(size_t index) const {
         JS_ASSERT(index < numOperands());
         return operands_[index].producer();
     }
     size_t numArgs() const {
         return argRegs_.length();
     }
     AnyRegister registerForArg(size_t index) const {
         JS_ASSERT(index < numArgs());
         return argRegs_[index];
     }
     const CallSiteDesc &desc() const {
         return desc_;
     }
     Callee callee() const {
         return callee_;
     }
     size_t dynamicCalleeOperandIndex() const {
         JS_ASSERT(callee_.which() == Callee::Dynamic);
         JS_ASSERT(numArgs() == numOperands() - 1);
         return numArgs();
     }
     size_t spIncrement() const {
         return spIncrement_;
     }
     bool possiblyCalls() const {
         return true;
     }
 };
 #undef INSTRUCTION_HEADER
 // Implement opcode casts now that the compiler can see the inheritance.
 #define OPCODE_CASTS(opcode)                                                \
     M##opcode *MDefinition::to##opcode()                                    \
     {                                                                       \
         JS_ASSERT(is##opcode());                                            \
         return static_cast<M##opcode *>(this);                              \
     }                                                                       \
     const M##opcode *MDefinition::to##opcode() const                        \
     {                                                                       \
         JS_ASSERT(is##opcode());                                            \
         return static_cast<const M##opcode *>(this);                        \
     }
 MIR_OPCODE_LIST(OPCODE_CASTS)
 #undef OPCODE_CASTS
 MDefinition *MNode::toDefinition()
 {
     JS_ASSERT(isDefinition());
     return (MDefinition *)this;
 }
 MResumePoint *MNode::toResumePoint()
 {
     JS_ASSERT(isResumePoint());
     return (MResumePoint *)this;
 }
 MInstruction *MDefinition::toInstruction()
 {
     JS_ASSERT(!isPhi());
     return (MInstruction *)this;
 }
 typedef Vector<MDefinition *, 8, IonAllocPolicy> MDefinitionVector;
 // Helper functions used to decide how to build MIR.
 bool ElementAccessIsDenseNative(MDefinition *obj, MDefinition *id);
 bool ElementAccessIsTypedArray(MDefinition *obj, MDefinition *id,
                                ScalarTypeDescr::Type *arrayType);
 bool ElementAccessIsPacked(types::CompilerConstraintList *constraints, MDefinition *obj);
 bool ElementAccessHasExtraIndexedProperty(types::CompilerConstraintList *constraints,
                                           MDefinition *obj);
 MIRType DenseNativeElementType(types::CompilerConstraintList *constraints, MDefinition *obj);
 bool PropertyReadNeedsTypeBarrier(JSContext *propertycx,
                                   types::CompilerConstraintList *constraints,
                                   types::TypeObjectKey *object, PropertyName *name,
                                   types::TemporaryTypeSet *observed, bool updateObserved);
 bool PropertyReadNeedsTypeBarrier(JSContext *propertycx,
                                   types::CompilerConstraintList *constraints,
                                   MDefinition *obj, PropertyName *name,
                                   types::TemporaryTypeSet *observed);
 bool PropertyReadOnPrototypeNeedsTypeBarrier(types::CompilerConstraintList *constraints,
                                              MDefinition *obj, PropertyName *name,
                                              types::TemporaryTypeSet *observed);
 bool PropertyReadIsIdempotent(types::CompilerConstraintList *constraints,
                               MDefinition *obj, PropertyName *name);
 void AddObjectsForPropertyRead(MDefinition *obj, PropertyName *name,
                                types::TemporaryTypeSet *observed);
 bool PropertyWriteNeedsTypeBarrier(TempAllocator &alloc, types::CompilerConstraintList *constraints,
                                    MBasicBlock *current, MDefinition **pobj,
                                    PropertyName *name, MDefinition **pvalue,
                                    bool canModify);
 } // namespace jit
 } // namespace js
 #endif /* jit_MIR_h */

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js/src/jit/MIR.h@6474c204b198 (annotated)

js/src/jit/MIR.h