bool
GreedyAllocator::informSafepoint(LSafepoint *safepoint)
{
    for (InlineListIterator<VirtualRegister> iter = liveSlots_.begin();
         iter != liveSlots_.end();
         iter++)
    {
        VirtualRegister *vr = *iter;
        if (vr->type() == LDefinition::OBJECT || vr->type() == LDefinition::BOX) {
            if (!safepoint->addGcSlot(vr->stackSlot()))
                return false;
            continue;
        }

#ifdef JS_NUNBOX32
        if (!IsNunbox(vr->type()))
            continue;

        VirtualRegister *other = otherHalfOfNunbox(vr);

        // Only bother if both halves are spilled.
        if (vr->hasStackSlot() && other->hasStackSlot()) {
            uint32 slot = BaseOfNunboxSlot(vr->type(), vr->stackSlot());
            if (!safepoint->addValueSlot(slot))
                return false;
        }
#endif
    }
    return true;
}

JSValue CallFrame::uncheckedActivation() const
{
    CodeBlock* codeBlock = this->codeBlock();
    RELEASE_ASSERT(codeBlock->needsActivation());
    VirtualRegister activationRegister = codeBlock->activationRegister();
    return registers()[activationRegister.offset()].jsValue();
}

bool
GreedyAllocator::prescanDefinition(LDefinition *def)
{
    // If the definition is fakeo, a redefinition, ignore it entirely. It's not
    // valid to kill it, and it doesn't matter if an input uses the same
    // register (thus it does not go into the disallow set).
    if (def->policy() == LDefinition::PASSTHROUGH)
        return true;

    VirtualRegister *vr = getVirtualRegister(def);

    // Add its register to the free pool.
    killReg(vr);

    // If it has a register, prevent it from being allocated this round.
    if (vr->hasRegister())
        disallowed.add(vr->reg());

    if (def->policy() == LDefinition::PRESET) {
        const LAllocation *a = def->output();
        if (a->isRegister()) {
            // Evict fixed registers. Use the unchecked version of set-add
            // because the register does not reflect any allocation state, so
            // it may have already been added.
            AnyRegister reg = GetPresetRegister(def);
            disallowed.addUnchecked(reg);
            if (!maybeEvict(reg))
                return false;
        }
    }
    return true;
}

GreedyAllocator::VirtualRegister *
GreedyAllocator::otherHalfOfNunbox(VirtualRegister *vreg)
{
    signed offset = OffsetToOtherHalfOfNunbox(vreg->type());
    VirtualRegister *other = &vars[vreg->def->virtualRegister() + offset];
    AssertTypesFormANunbox(vreg->type(), other->type());
    return other;
}

void
JSONSpewer::spewIntervals(LinearScanAllocator *regalloc)
{
    if (!fp_)
        return;

    beginObjectProperty("intervals");
    beginListProperty("blocks");

    for (size_t bno = 0; bno < regalloc->graph.numBlocks(); bno++) {
        beginObject();
        integerProperty("number", bno);
        beginListProperty("vregs");

        LBlock *lir = regalloc->graph.getBlock(bno);
        for (LInstructionIterator ins = lir->begin(); ins != lir->end(); ins++) {
            for (size_t k = 0; k < ins->numDefs(); k++) {
                VirtualRegister *vreg = &regalloc->vregs[ins->getDef(k)->virtualRegister()];

                beginObject();
                integerProperty("vreg", vreg->reg());
                beginListProperty("intervals");

                for (size_t i = 0; i < vreg->numIntervals(); i++) {
                    LiveInterval *live = vreg->getInterval(i);

                    if (live->numRanges()) {
                        beginObject();
                        property("allocation");
                        fprintf(fp_, "\"");
                        LAllocation::PrintAllocation(fp_, live->getAllocation());
                        fprintf(fp_, "\"");
                        beginListProperty("ranges");

                        for (size_t j = 0; j < live->numRanges(); j++) {
                            beginObject();
                            integerProperty("start", live->getRange(j)->from.pos());
                            integerProperty("end", live->getRange(j)->to.pos());
                            endObject();
                        }

                        endList();
                        endObject();
                    }
                }

                endList();
                endObject();
            }
        }

        endList();
        endObject();
    }

    endList();
    endObject();
}

 VirtualRegister assign(const Vector<unsigned>& allocation, VirtualRegister src)
 {
     VirtualRegister result = src;
     if (result.isLocal()) {
         unsigned myAllocation = allocation[result.toLocal()];
         if (myAllocation == UINT_MAX)
             result = VirtualRegister();
         else
             result = virtualRegisterForLocal(myAllocation);
     }
     return result;
 }

void
GreedyAllocator::assertValidRegisterState()
{
#ifdef DEBUG
    // Assert that for each taken register in state.free, that it maps to a vr
    // and that that vr has that register.
    for (AnyRegisterIterator iter; iter.more(); iter++) {
        AnyRegister reg = *iter;
        VirtualRegister *vr = state[reg];
        JS_ASSERT(!vr == state.free.has(reg));
        JS_ASSERT_IF(vr, vr->reg() == reg);
    }
#endif
}

void
JSONSpewer::spewRanges(BacktrackingAllocator* regalloc)
{
    if (!fp_)
        return;

    beginObjectProperty("ranges");
    beginListProperty("blocks");

    for (size_t bno = 0; bno < regalloc->graph.numBlocks(); bno++) {
        beginObject();
        integerProperty("number", bno);
        beginListProperty("vregs");

        LBlock* lir = regalloc->graph.getBlock(bno);
        for (LInstructionIterator ins = lir->begin(); ins != lir->end(); ins++) {
            for (size_t k = 0; k < ins->numDefs(); k++) {
                uint32_t id = ins->getDef(k)->virtualRegister();
                VirtualRegister* vreg = &regalloc->vregs[id];

                beginObject();
                integerProperty("vreg", id);
                beginListProperty("ranges");

                for (LiveRange::RegisterLinkIterator iter = vreg->rangesBegin(); iter; iter++) {
                    LiveRange* range = LiveRange::get(*iter);

                    beginObject();
                    property("allocation");
                    fprintf(fp_, "\"%s\"", range->bundle()->allocation().toString());
                    integerProperty("start", range->from().bits());
                    integerProperty("end", range->to().bits());
                    endObject();
                }

                endList();
                endObject();
            }
        }

        endList();
        endObject();
    }

    endList();
    endObject();
}

void OSREntryData::dumpInContext(PrintStream& out, DumpContext* context) const
{
    out.print("bc#", m_bytecodeIndex, ", machine code offset = ", m_machineCodeOffset);
    out.print(", stack rules = [");
    
    auto printOperand = [&] (VirtualRegister reg) {
        out.print(inContext(m_expectedValues.operand(reg), context), " (");
        VirtualRegister toReg;
        bool overwritten = false;
        for (OSREntryReshuffling reshuffling : m_reshufflings) {
            if (reg == VirtualRegister(reshuffling.fromOffset)) {
                toReg = VirtualRegister(reshuffling.toOffset);
                break;
            }
            if (reg == VirtualRegister(reshuffling.toOffset))
                overwritten = true;
        }
        if (!overwritten && !toReg.isValid())
            toReg = reg;
        if (toReg.isValid()) {
            if (toReg.isLocal() && !m_machineStackUsed.get(toReg.toLocal()))
                out.print("ignored");
            else
                out.print("maps to ", toReg);
        } else
            out.print("overwritten");
        if (reg.isLocal() && m_localsForcedDouble.get(reg.toLocal()))
            out.print(", forced double");
        if (reg.isLocal() && m_localsForcedAnyInt.get(reg.toLocal()))
            out.print(", forced machine int");
        out.print(")");
    };
    
    CommaPrinter comma;
    for (size_t argumentIndex = m_expectedValues.numberOfArguments(); argumentIndex--;) {
        out.print(comma, "arg", argumentIndex, ":");
        printOperand(virtualRegisterForArgument(argumentIndex));
    }
    for (size_t localIndex = 0; localIndex < m_expectedValues.numberOfLocals(); ++localIndex) {
        out.print(comma, "loc", localIndex, ":");
        printOperand(virtualRegisterForLocal(localIndex));
    }
    
    out.print("], machine stack used = ", m_machineStackUsed);
}

bool argumentsInvolveStackSlot(InlineCallFrame* inlineCallFrame, VirtualRegister reg)
{
    if (!inlineCallFrame)
        return (reg.isArgument() && reg.toArgument()) || reg.isHeader();
    
    if (inlineCallFrame->isClosureCall
        && reg == VirtualRegister(inlineCallFrame->stackOffset + CallFrameSlot::callee))
        return true;
    
    if (inlineCallFrame->isVarargs()
        && reg == VirtualRegister(inlineCallFrame->stackOffset + CallFrameSlot::argumentCount))
        return true;
    
    unsigned numArguments = inlineCallFrame->arguments.size() - 1;
    VirtualRegister argumentStart =
        VirtualRegister(inlineCallFrame->stackOffset) + CallFrame::argumentOffset(0);
    return reg >= argumentStart && reg < argumentStart + numArguments;
}

EncodedJSValue JSLexicalEnvironment::argumentsGetter(ExecState*, JSObject* slotBase, EncodedJSValue, PropertyName)
{
    JSLexicalEnvironment* lexicalEnvironment = jsCast<JSLexicalEnvironment*>(slotBase);
    CallFrame* callFrame = CallFrame::create(reinterpret_cast<Register*>(lexicalEnvironment->m_registers));
    return JSValue::encode(jsUndefined());

    VirtualRegister argumentsRegister = callFrame->codeBlock()->argumentsRegister();
    if (JSValue arguments = callFrame->uncheckedR(argumentsRegister.offset()).jsValue())
        return JSValue::encode(arguments);
    int realArgumentsRegister = unmodifiedArgumentsRegister(argumentsRegister).offset();

    JSValue arguments = JSValue(Arguments::create(callFrame->vm(), callFrame));
    callFrame->uncheckedR(argumentsRegister.offset()) = arguments;
    callFrame->uncheckedR(realArgumentsRegister) = arguments;
    
    ASSERT(callFrame->uncheckedR(realArgumentsRegister).jsValue().inherits(Arguments::info()));
    return JSValue::encode(callFrame->uncheckedR(realArgumentsRegister).jsValue());
}

bool
GreedyAllocator::evict(AnyRegister reg)
{
    VirtualRegister *vr = state[reg];
    JS_ASSERT(vr->reg() == reg);

    // If the virtual register does not have a stack slot, allocate one now.
    allocateStack(vr);

    // We're allocating bottom-up, so eviction *restores* a register, otherwise
    // it could not be used downstream.
    if (!restore(vr->backingStack(), reg))
        return false;

    freeReg(reg);
    vr->unsetRegister();
    return true;
}

void
C1Spewer::spewRanges(GenericPrinter& out, BacktrackingAllocator* regalloc, LNode* ins)
{
    for (size_t k = 0; k < ins->numDefs(); k++) {
        uint32_t id = ins->getDef(k)->virtualRegister();
        VirtualRegister* vreg = &regalloc->vregs[id];

        for (LiveRange::RegisterLinkIterator iter = vreg->rangesBegin(); iter; iter++) {
            LiveRange* range = LiveRange::get(*iter);
            out.printf("%d object \"", id);
            out.printf("%s", range->bundle()->allocation().toString().get());
            out.printf("\" %d -1", id);
            out.printf(" [%u, %u[", range->from().bits(), range->to().bits());
            for (UsePositionIterator usePos(range->usesBegin()); usePos; usePos++)
                out.printf(" %u M", usePos->pos.bits());
            out.printf(" \"\"\n");
        }
    }
}

EncodedJSValue JSActivation::argumentsGetter(ExecState*, EncodedJSValue slotBase, EncodedJSValue, PropertyName)
{
    JSActivation* activation = jsCast<JSActivation*>(JSValue::decode(slotBase));
    CallFrame* callFrame = CallFrame::create(reinterpret_cast<Register*>(activation->m_registers));
    ASSERT(!activation->isTornOff() && (callFrame->codeBlock()->usesArguments() || callFrame->codeBlock()->usesEval()));
    if (activation->isTornOff() || !(callFrame->codeBlock()->usesArguments() || callFrame->codeBlock()->usesEval()))
        return JSValue::encode(jsUndefined());

    VirtualRegister argumentsRegister = callFrame->codeBlock()->argumentsRegister();
    if (JSValue arguments = callFrame->uncheckedR(argumentsRegister.offset()).jsValue())
        return JSValue::encode(arguments);
    int realArgumentsRegister = unmodifiedArgumentsRegister(argumentsRegister).offset();

    JSValue arguments = JSValue(Arguments::create(callFrame->vm(), callFrame));
    callFrame->uncheckedR(argumentsRegister.offset()) = arguments;
    callFrame->uncheckedR(realArgumentsRegister) = arguments;
    
    ASSERT(callFrame->uncheckedR(realArgumentsRegister).jsValue().inherits(Arguments::info()));
    return JSValue::encode(callFrame->uncheckedR(realArgumentsRegister).jsValue());
}

bool
GreedyAllocator::prescanUses(LInstruction *ins)
{
    for (size_t i = 0; i < ins->numOperands(); i++) {
        LAllocation *a = ins->getOperand(i);
        if (!a->isUse()) {
            JS_ASSERT(a->isConstant());
            continue;
        }

        LUse *use = a->toUse();
        VirtualRegister *vr = getVirtualRegister(use);
        if (use->policy() == LUse::FIXED) {
            // A def or temp may use the same register, so we have to use the
            // unchecked version.
            disallowed.addUnchecked(GetFixedRegister(vr->def, use));
        } else if (vr->hasRegister()) {
            discouraged.addUnchecked(vr->reg());
        }
    }
    return true;
}

bool
GreedyAllocator::buildPhiMoves(LBlock *block)
{
    IonSpew(IonSpew_RegAlloc, " Merging phi state."); 

    phiMoves = Mover();

    MBasicBlock *mblock = block->mir();
    if (!mblock->successorWithPhis())
        return true;

    // Insert moves from our state into our successor's phi.
    uint32 pos = mblock->positionInPhiSuccessor();
    LBlock *successor = mblock->successorWithPhis()->lir();
    for (size_t i = 0; i < successor->numPhis(); i++) {
        LPhi *phi = successor->getPhi(i);
        JS_ASSERT(phi->numDefs() == 1);

        VirtualRegister *phiReg = getVirtualRegister(phi->getDef(0));
        allocateStack(phiReg);

        LAllocation *in = phi->getOperand(pos);
        VirtualRegister *inReg = getVirtualRegister(in->toUse());
        allocateStack(inReg);

        // Try to get a register for the input.
        if (!inReg->hasRegister() && !allocatableRegs().empty(inReg->isDouble())) {
            if (!allocateReg(inReg))
                return false;
        }

        // Add a move from the input to the phi.
        if (inReg->hasRegister()) {
            if (!phiMoves.move(inReg->reg(), phiReg->backingStack()))
                return false;
        } else {
            if (!phiMoves.move(inReg->backingStack(), phiReg->backingStack()))
                return false;
        }
    }

    return true;
}

void
C1Spewer::spewIntervals(FILE *fp, LinearScanAllocator *regalloc, LInstruction *ins, size_t &nextId)
{
    for (size_t k = 0; k < ins->numDefs(); k++) {
        VirtualRegister *vreg = &regalloc->vregs[ins->getDef(k)->virtualRegister()];

        for (size_t i = 0; i < vreg->numIntervals(); i++) {
            LiveInterval *live = vreg->getInterval(i);
            if (live->numRanges()) {
                fprintf(fp, "%d object \"", (i == 0) ? vreg->id() : int32_t(nextId++));
                fprintf(fp, "%s", live->getAllocation()->toString());
                fprintf(fp, "\" %d -1", vreg->id());
                for (size_t j = 0; j < live->numRanges(); j++) {
                    fprintf(fp, " [%d, %d[", live->getRange(j)->from.pos(),
                            live->getRange(j)->to.pos());
                }
                for (UsePositionIterator usePos(live->usesBegin()); usePos != live->usesEnd(); usePos++)
                    fprintf(fp, " %d M", usePos->pos.pos());
                fprintf(fp, " \"\"\n");
            }
        }
    }
}

void emitSetupVarargsFrameFastCase(CCallHelpers& jit, GPRReg numUsedSlotsGPR, GPRReg scratchGPR1, GPRReg scratchGPR2, GPRReg scratchGPR3, ValueRecovery argCountRecovery, VirtualRegister firstArgumentReg, unsigned firstVarArgOffset, CCallHelpers::JumpList& slowCase)
{
    CCallHelpers::JumpList end;
    
    if (argCountRecovery.isConstant()) {
        // FIXME: We could constant-fold a lot of the computation below in this case.
        // https://bugs.webkit.org/show_bug.cgi?id=141486
        jit.move(CCallHelpers::TrustedImm32(argCountRecovery.constant().asInt32()), scratchGPR1);
    } else
        jit.load32(CCallHelpers::payloadFor(argCountRecovery.virtualRegister()), scratchGPR1);
    if (firstVarArgOffset) {
        CCallHelpers::Jump sufficientArguments = jit.branch32(CCallHelpers::GreaterThan, scratchGPR1, CCallHelpers::TrustedImm32(firstVarArgOffset + 1));
        jit.move(CCallHelpers::TrustedImm32(1), scratchGPR1);
        CCallHelpers::Jump endVarArgs = jit.jump();
        sufficientArguments.link(&jit);
        jit.sub32(CCallHelpers::TrustedImm32(firstVarArgOffset), scratchGPR1);
        endVarArgs.link(&jit);
    }
    slowCase.append(jit.branch32(CCallHelpers::Above, scratchGPR1, CCallHelpers::TrustedImm32(maxArguments + 1)));
    
    emitSetVarargsFrame(jit, scratchGPR1, true, numUsedSlotsGPR, scratchGPR2);

    slowCase.append(jit.branchPtr(CCallHelpers::Above, CCallHelpers::AbsoluteAddress(jit.vm()->addressOfStackLimit()), scratchGPR2));

    // Initialize ArgumentCount.
    jit.store32(scratchGPR1, CCallHelpers::Address(scratchGPR2, JSStack::ArgumentCount * static_cast<int>(sizeof(Register)) + PayloadOffset));

    // Copy arguments.
    jit.signExtend32ToPtr(scratchGPR1, scratchGPR1);
    CCallHelpers::Jump done = jit.branchSubPtr(CCallHelpers::Zero, CCallHelpers::TrustedImm32(1), scratchGPR1);
    // scratchGPR1: argumentCount

    CCallHelpers::Label copyLoop = jit.label();
    int argOffset = (firstArgumentReg.offset() - 1 + firstVarArgOffset) * static_cast<int>(sizeof(Register));
#if USE(JSVALUE64)
    jit.load64(CCallHelpers::BaseIndex(GPRInfo::callFrameRegister, scratchGPR1, CCallHelpers::TimesEight, argOffset), scratchGPR3);
    jit.store64(scratchGPR3, CCallHelpers::BaseIndex(scratchGPR2, scratchGPR1, CCallHelpers::TimesEight, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register))));
#else // USE(JSVALUE64), so this begins the 32-bit case
    jit.load32(CCallHelpers::BaseIndex(GPRInfo::callFrameRegister, scratchGPR1, CCallHelpers::TimesEight, argOffset + TagOffset), scratchGPR3);
    jit.store32(scratchGPR3, CCallHelpers::BaseIndex(scratchGPR2, scratchGPR1, CCallHelpers::TimesEight, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)) + TagOffset));
    jit.load32(CCallHelpers::BaseIndex(GPRInfo::callFrameRegister, scratchGPR1, CCallHelpers::TimesEight, argOffset + PayloadOffset), scratchGPR3);
    jit.store32(scratchGPR3, CCallHelpers::BaseIndex(scratchGPR2, scratchGPR1, CCallHelpers::TimesEight, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)) + PayloadOffset));
#endif // USE(JSVALUE64), end of 32-bit case
    jit.branchSubPtr(CCallHelpers::NonZero, CCallHelpers::TrustedImm32(1), scratchGPR1).linkTo(copyLoop, &jit);
    
    done.link(&jit);
}

    bool run()
    {
        SharedSymbolTable* symbolTable = codeBlock()->symbolTable();

        // This enumerates the locals that we actually care about and packs them. So for example
        // if we use local 1, 3, 4, 5, 7, then we remap them: 1->0, 3->1, 4->2, 5->3, 7->4. We
        // treat a variable as being "used" if there exists an access to it (SetLocal, GetLocal,
        // Flush, PhantomLocal).
        
        BitVector usedLocals;
        
        // Collect those variables that are used from IR.
        bool hasGetLocalUnlinked = false;
        for (BlockIndex blockIndex = m_graph.numBlocks(); blockIndex--;) {
            BasicBlock* block = m_graph.block(blockIndex);
            if (!block)
                continue;
            for (unsigned nodeIndex = block->size(); nodeIndex--;) {
                Node* node = block->at(nodeIndex);
                switch (node->op()) {
                case GetLocal:
                case SetLocal:
                case Flush:
                case PhantomLocal: {
                    VariableAccessData* variable = node->variableAccessData();
                    if (variable->local().isArgument())
                        break;
                    usedLocals.set(variable->local().toLocal());
                    break;
                }
                    
                case GetLocalUnlinked: {
                    VirtualRegister operand = node->unlinkedLocal();
                    if (operand.isArgument())
                        break;
                    usedLocals.set(operand.toLocal());
                    hasGetLocalUnlinked = true;
                    break;
                }
                    
                default:
                    break;
                }
            }
        }
        
        // Ensure that captured variables and captured inline arguments are pinned down.
        // They should have been because of flushes, except that the flushes can be optimized
        // away.
        if (symbolTable) {
            for (int i = symbolTable->captureStart(); i > symbolTable->captureEnd(); i--)
                usedLocals.set(VirtualRegister(i).toLocal());
        }
        if (codeBlock()->usesArguments()) {
            usedLocals.set(codeBlock()->argumentsRegister().toLocal());
            usedLocals.set(unmodifiedArgumentsRegister(codeBlock()->argumentsRegister()).toLocal());
        }
        if (codeBlock()->uncheckedActivationRegister().isValid())
            usedLocals.set(codeBlock()->activationRegister().toLocal());
        for (InlineCallFrameSet::iterator iter = m_graph.m_inlineCallFrames->begin(); !!iter; ++iter) {
            InlineCallFrame* inlineCallFrame = *iter;
            if (!inlineCallFrame->executable->usesArguments())
                continue;
            
            VirtualRegister argumentsRegister = m_graph.argumentsRegisterFor(inlineCallFrame);
            usedLocals.set(argumentsRegister.toLocal());
            usedLocals.set(unmodifiedArgumentsRegister(argumentsRegister).toLocal());
            
            for (unsigned argument = inlineCallFrame->arguments.size(); argument-- > 1;) {
                usedLocals.set(VirtualRegister(
                    virtualRegisterForArgument(argument).offset() +
                    inlineCallFrame->stackOffset).toLocal());
            }
        }
        
        Vector<unsigned> allocation(usedLocals.size());
        m_graph.m_nextMachineLocal = 0;
        for (unsigned i = 0; i < usedLocals.size(); ++i) {
            if (!usedLocals.get(i)) {
                allocation[i] = UINT_MAX;
                continue;
            }
            
            allocation[i] = m_graph.m_nextMachineLocal++;
        }
        
        for (unsigned i = m_graph.m_variableAccessData.size(); i--;) {
            VariableAccessData* variable = &m_graph.m_variableAccessData[i];
            if (!variable->isRoot())
                continue;
            
            if (variable->local().isArgument()) {
                variable->machineLocal() = variable->local();
                continue;
            }
            
            size_t local = variable->local().toLocal();
            if (local >= allocation.size())
                continue;
            
//.........这里部分代码省略.........

    void handleBlockForTryCatch(BasicBlock* block, InsertionSet& insertionSet)
    {
        HandlerInfo* currentExceptionHandler = nullptr;
        FastBitVector liveAtCatchHead;
        liveAtCatchHead.resize(m_graph.block(0)->variablesAtTail.numberOfLocals());

        HandlerInfo* cachedHandlerResult;
        CodeOrigin cachedCodeOrigin;
        auto catchHandler = [&] (CodeOrigin origin) -> HandlerInfo* {
            ASSERT(origin);
            if (origin == cachedCodeOrigin)
                return cachedHandlerResult;

            unsigned bytecodeIndexToCheck = origin.bytecodeIndex;

            cachedCodeOrigin = origin;

            while (1) {
                InlineCallFrame* inlineCallFrame = origin.inlineCallFrame;
                CodeBlock* codeBlock = m_graph.baselineCodeBlockFor(inlineCallFrame);
                if (HandlerInfo* handler = codeBlock->handlerForBytecodeOffset(bytecodeIndexToCheck)) {
                    liveAtCatchHead.clearAll();

                    unsigned catchBytecodeIndex = handler->target;
                    m_graph.forAllLocalsLiveInBytecode(CodeOrigin(catchBytecodeIndex, inlineCallFrame), [&] (VirtualRegister operand) {
                        liveAtCatchHead[operand.toLocal()] = true;
                    });

                    cachedHandlerResult = handler;
                    break;
                }

                if (!inlineCallFrame) {
                    cachedHandlerResult = nullptr;
                    break;
                }

                bytecodeIndexToCheck = inlineCallFrame->directCaller.bytecodeIndex;
                origin = inlineCallFrame->directCaller;
            }

            return cachedHandlerResult;
        };

        Operands<VariableAccessData*> currentBlockAccessData(block->variablesAtTail.numberOfArguments(), block->variablesAtTail.numberOfLocals(), nullptr);
        HashSet<InlineCallFrame*> seenInlineCallFrames;

        auto flushEverything = [&] (NodeOrigin origin, unsigned index) {
            RELEASE_ASSERT(currentExceptionHandler);
            auto flush = [&] (VirtualRegister operand, bool alwaysInsert) {
                if ((operand.isLocal() && liveAtCatchHead[operand.toLocal()]) 
                    || operand.isArgument()
                    || alwaysInsert) {

                    ASSERT(isValidFlushLocation(block, index, operand));

                    VariableAccessData* accessData = currentBlockAccessData.operand(operand);
                    if (!accessData)
                        accessData = newVariableAccessData(operand);

                    currentBlockAccessData.operand(operand) = accessData;

                    insertionSet.insertNode(index, SpecNone, 
                        Flush, origin, OpInfo(accessData));
                }
            };

            for (unsigned local = 0; local < block->variablesAtTail.numberOfLocals(); local++)
                flush(virtualRegisterForLocal(local), false);
            for (InlineCallFrame* inlineCallFrame : seenInlineCallFrames)
                flush(VirtualRegister(inlineCallFrame->stackOffset + CallFrame::thisArgumentOffset()), true);
            flush(VirtualRegister(CallFrame::thisArgumentOffset()), true);

            seenInlineCallFrames.clear();
        };

        for (unsigned nodeIndex = 0; nodeIndex < block->size(); nodeIndex++) {
            Node* node = block->at(nodeIndex);

            {
                HandlerInfo* newHandler = catchHandler(node->origin.semantic);
                if (newHandler != currentExceptionHandler && currentExceptionHandler)
                    flushEverything(node->origin, nodeIndex);
                currentExceptionHandler = newHandler;
            }

            if (currentExceptionHandler && (node->op() == SetLocal || node->op() == SetArgument)) {
                InlineCallFrame* inlineCallFrame = node->origin.semantic.inlineCallFrame;
                if (inlineCallFrame)
                    seenInlineCallFrames.add(inlineCallFrame);
                VirtualRegister operand = node->local();

                int stackOffset = inlineCallFrame ? inlineCallFrame->stackOffset : 0;
                if ((operand.isLocal() && liveAtCatchHead[operand.toLocal()])
                    || operand.isArgument()
                    || (operand.offset() == stackOffset + CallFrame::thisArgumentOffset())) {

                    ASSERT(isValidFlushLocation(block, nodeIndex, operand));

                    VariableAccessData* variableAccessData = currentBlockAccessData.operand(operand);
//.........这里部分代码省略.........