C++ Operands::operandForIndex方法代码示例

void JITCode::reconstruct(
    ExecState* exec, CodeBlock* codeBlock, CodeOrigin codeOrigin, unsigned streamIndex,
    Operands<JSValue>& result)
{
    Operands<ValueRecovery> recoveries;
    reconstruct(codeBlock, codeOrigin, streamIndex, recoveries);
    
    result = Operands<JSValue>(OperandsLike, recoveries);
    for (size_t i = result.size(); i--;) {
        int operand = result.operandForIndex(i);
        
        if (operandIsArgument(operand)
            && !VirtualRegister(operand).toArgument()
            && codeBlock->codeType() == FunctionCode
            && codeBlock->specializationKind() == CodeForConstruct) {
            // Ugh. If we're in a constructor, the 'this' argument may hold garbage. It will
            // also never be used. It doesn't matter what we put into the value for this,
            // but it has to be an actual value that can be grokked by subsequent DFG passes,
            // so we sanitize it here by turning it into Undefined.
            result[i] = jsUndefined();
            continue;
        }
        
        ValueRecovery recovery = recoveries[i];
        JSValue value;
        switch (recovery.technique()) {
        case AlreadyInJSStack:
        case AlreadyInJSStackAsUnboxedCell:
        case AlreadyInJSStackAsUnboxedBoolean:
            value = exec->r(operand).jsValue();
            break;
        case AlreadyInJSStackAsUnboxedInt32:
            value = jsNumber(exec->r(operand).unboxedInt32());
            break;
        case AlreadyInJSStackAsUnboxedInt52:
            value = jsNumber(exec->r(operand).unboxedInt52());
            break;
        case AlreadyInJSStackAsUnboxedDouble:
            value = jsDoubleNumber(exec->r(operand).unboxedDouble());
            break;
        case Constant:
            value = recovery.constant();
            break;
        default:
            RELEASE_ASSERT_NOT_REACHED();
            break;
        }
        result[i] = value;
    }
}

//.........这里部分代码省略.........
        const ValueRecovery& recovery = operands[index];
        
        switch (recovery.technique()) {
        case DisplacedInJSStack:
        case Int32DisplacedInJSStack:
        case DoubleDisplacedInJSStack:
        case CellDisplacedInJSStack:
        case BooleanDisplacedInJSStack:
            m_jit.load32(
                AssemblyHelpers::tagFor(recovery.virtualRegister()),
                GPRInfo::regT0);
            m_jit.load32(
                AssemblyHelpers::payloadFor(recovery.virtualRegister()),
                GPRInfo::regT1);
            m_jit.store32(
                GPRInfo::regT0,
                &bitwise_cast<EncodedValueDescriptor*>(scratch + index)->asBits.tag);
            m_jit.store32(
                GPRInfo::regT1,
                &bitwise_cast<EncodedValueDescriptor*>(scratch + index)->asBits.payload);
            break;
            
        default:
            break;
        }
    }
    
    // 7) Do all data format conversions and store the results into the stack.
    
    bool haveArguments = false;
    
    for (size_t index = 0; index < operands.size(); ++index) {
        const ValueRecovery& recovery = operands[index];
        int operand = operands.operandForIndex(index);
        
        switch (recovery.technique()) {
        case InPair:
        case DisplacedInJSStack:
            m_jit.load32(
                &bitwise_cast<EncodedValueDescriptor*>(scratch + index)->asBits.tag,
                GPRInfo::regT0);
            m_jit.load32(
                &bitwise_cast<EncodedValueDescriptor*>(scratch + index)->asBits.payload,
                GPRInfo::regT1);
            m_jit.store32(
                GPRInfo::regT0,
                AssemblyHelpers::tagFor(operand));
            m_jit.store32(
                GPRInfo::regT1,
                AssemblyHelpers::payloadFor(operand));
            break;
            
        case InFPR:
        case DoubleDisplacedInJSStack:
            m_jit.move(AssemblyHelpers::TrustedImmPtr(scratch + index), GPRInfo::regT0);
            m_jit.loadDouble(GPRInfo::regT0, FPRInfo::fpRegT0);
            m_jit.purifyNaN(FPRInfo::fpRegT0);
            m_jit.storeDouble(FPRInfo::fpRegT0, AssemblyHelpers::addressFor(operand));
            break;

        case UnboxedInt32InGPR:
        case Int32DisplacedInJSStack:
            m_jit.load32(
                &bitwise_cast<EncodedValueDescriptor*>(scratch + index)->asBits.payload,
                GPRInfo::regT0);
            m_jit.store32(

//.........这里部分代码省略.........
    
    // Now, all FPRs are also free.
    
    // 6) Save all state from the stack into the scratch buffer. For simplicity we
    //    do this even for state that's already in the right place on the stack.
    //    It makes things simpler later.

    for (size_t index = 0; index < operands.size(); ++index) {
        const ValueRecovery& recovery = operands[index];
        
        switch (recovery.technique()) {
        case DisplacedInJSStack:
        case CellDisplacedInJSStack:
        case BooleanDisplacedInJSStack:
        case Int32DisplacedInJSStack:
        case DoubleDisplacedInJSStack:
        case Int52DisplacedInJSStack:
        case StrictInt52DisplacedInJSStack:
            m_jit.load64(AssemblyHelpers::addressFor(recovery.virtualRegister()), GPRInfo::regT0);
            m_jit.store64(GPRInfo::regT0, scratch + index);
            break;
            
        default:
            break;
        }
    }
    
    // 7) Do all data format conversions and store the results into the stack.
    
    bool haveArguments = false;
    
    for (size_t index = 0; index < operands.size(); ++index) {
        const ValueRecovery& recovery = operands[index];
        int operand = operands.operandForIndex(index);
        
        switch (recovery.technique()) {
        case InGPR:
        case UnboxedCellInGPR:
        case DisplacedInJSStack:
        case CellDisplacedInJSStack:
        case BooleanDisplacedInJSStack:
            m_jit.load64(scratch + index, GPRInfo::regT0);
            m_jit.store64(GPRInfo::regT0, AssemblyHelpers::addressFor(operand));
            break;
            
        case UnboxedInt32InGPR:
        case Int32DisplacedInJSStack:
            m_jit.load64(scratch + index, GPRInfo::regT0);
            m_jit.zeroExtend32ToPtr(GPRInfo::regT0, GPRInfo::regT0);
            m_jit.or64(GPRInfo::tagTypeNumberRegister, GPRInfo::regT0);
            m_jit.store64(GPRInfo::regT0, AssemblyHelpers::addressFor(operand));
            break;
            
        case UnboxedInt52InGPR:
        case Int52DisplacedInJSStack:
            m_jit.load64(scratch + index, GPRInfo::regT0);
            m_jit.rshift64(
                AssemblyHelpers::TrustedImm32(JSValue::int52ShiftAmount), GPRInfo::regT0);
            m_jit.boxInt52(GPRInfo::regT0, GPRInfo::regT0, GPRInfo::regT1, FPRInfo::fpRegT0);
            m_jit.store64(GPRInfo::regT0, AssemblyHelpers::addressFor(operand));
            break;
            
        case UnboxedStrictInt52InGPR:
        case StrictInt52DisplacedInJSStack:
            m_jit.load64(scratch + index, GPRInfo::regT0);
            m_jit.boxInt52(GPRInfo::regT0, GPRInfo::regT0, GPRInfo::regT1, FPRInfo::fpRegT0);

void VariableEventStream::reconstruct(
    CodeBlock* codeBlock, CodeOrigin codeOrigin, MinifiedGraph& graph,
    unsigned index, Operands<ValueRecovery>& valueRecoveries) const
{
    ASSERT(codeBlock->jitType() == JITCode::DFGJIT);
    CodeBlock* baselineCodeBlock = codeBlock->baselineVersion();
    
    unsigned numVariables;
    if (codeOrigin.inlineCallFrame)
        numVariables = baselineCodeBlockForInlineCallFrame(codeOrigin.inlineCallFrame)->m_numCalleeRegisters + VirtualRegister(codeOrigin.inlineCallFrame->stackOffset).toLocal() + 1;
    else
        numVariables = baselineCodeBlock->m_numCalleeRegisters;
    
    // Crazy special case: if we're at index == 0 then this must be an argument check
    // failure, in which case all variables are already set up. The recoveries should
    // reflect this.
    if (!index) {
        valueRecoveries = Operands<ValueRecovery>(codeBlock->numParameters(), numVariables);
        for (size_t i = 0; i < valueRecoveries.size(); ++i) {
            valueRecoveries[i] = ValueRecovery::displacedInJSStack(
                VirtualRegister(valueRecoveries.operandForIndex(i)), DataFormatJS);
        }
        return;
    }
    
    // Step 1: Find the last checkpoint, and figure out the number of virtual registers as we go.
    unsigned startIndex = index - 1;
    while (at(startIndex).kind() != Reset)
        startIndex--;
    
    // Step 2: Create a mock-up of the DFG's state and execute the events.
    Operands<ValueSource> operandSources(codeBlock->numParameters(), numVariables);
    for (unsigned i = operandSources.size(); i--;)
        operandSources[i] = ValueSource(SourceIsDead);
    HashMap<MinifiedID, MinifiedGenerationInfo> generationInfos;
    for (unsigned i = startIndex; i < index; ++i) {
        const VariableEvent& event = at(i);
        switch (event.kind()) {
        case Reset:
            // nothing to do.
            break;
        case BirthToFill:
        case BirthToSpill:
        case Birth: {
            MinifiedGenerationInfo info;
            info.update(event);
            generationInfos.add(event.id(), info);
            break;
        }
        case Fill:
        case Spill:
        case Death: {
            HashMap<MinifiedID, MinifiedGenerationInfo>::iterator iter = generationInfos.find(event.id());
            ASSERT(iter != generationInfos.end());
            iter->value.update(event);
            break;
        }
        case MovHintEvent:
            if (operandSources.hasOperand(event.bytecodeRegister()))
                operandSources.setOperand(event.bytecodeRegister(), ValueSource(event.id()));
            break;
        case SetLocalEvent:
            if (operandSources.hasOperand(event.bytecodeRegister()))
                operandSources.setOperand(event.bytecodeRegister(), ValueSource::forDataFormat(event.machineRegister(), event.dataFormat()));
            break;
        default:
            RELEASE_ASSERT_NOT_REACHED();
            break;
        }
    }
    
    // Step 3: Compute value recoveries!
    valueRecoveries = Operands<ValueRecovery>(codeBlock->numParameters(), numVariables);
    for (unsigned i = 0; i < operandSources.size(); ++i) {
        ValueSource& source = operandSources[i];
        if (source.isTriviallyRecoverable()) {
            valueRecoveries[i] = source.valueRecovery();
            continue;
        }
        
        ASSERT(source.kind() == HaveNode);
        MinifiedNode* node = graph.at(source.id());
        MinifiedGenerationInfo info = generationInfos.get(source.id());
        if (!info.alive) {
            valueRecoveries[i] = ValueRecovery::constant(jsUndefined());
            continue;
        }

        if (tryToSetConstantRecovery(valueRecoveries[i], node))
            continue;
        
        ASSERT(info.format != DataFormatNone);
        
        if (info.filled) {
            if (info.format == DataFormatDouble) {
                valueRecoveries[i] = ValueRecovery::inFPR(info.u.fpr, DataFormatDouble);
                continue;
            }
#if USE(JSVALUE32_64)
            if (info.format & DataFormatJS) {
//.........这里部分代码省略.........

void OSRExitCompiler::emitRestoreArguments(const Operands<ValueRecovery>& operands)
{
    HashMap<MinifiedID, int> alreadyAllocatedArguments; // Maps phantom arguments node ID to operand.
    for (size_t index = 0; index < operands.size(); ++index) {
        const ValueRecovery& recovery = operands[index];
        int operand = operands.operandForIndex(index);
        
        if (recovery.technique() != DirectArgumentsThatWereNotCreated
            && recovery.technique() != ClonedArgumentsThatWereNotCreated)
            continue;
        
        MinifiedID id = recovery.nodeID();
        auto iter = alreadyAllocatedArguments.find(id);
        if (iter != alreadyAllocatedArguments.end()) {
            JSValueRegs regs = JSValueRegs::withTwoAvailableRegs(GPRInfo::regT0, GPRInfo::regT1);
            m_jit.loadValue(CCallHelpers::addressFor(iter->value), regs);
            m_jit.storeValue(regs, CCallHelpers::addressFor(operand));
            continue;
        }
        
        InlineCallFrame* inlineCallFrame =
            m_jit.codeBlock()->jitCode()->dfg()->minifiedDFG.at(id)->inlineCallFrame();

        int stackOffset;
        if (inlineCallFrame)
            stackOffset = inlineCallFrame->stackOffset;
        else
            stackOffset = 0;
        
        if (!inlineCallFrame || inlineCallFrame->isClosureCall) {
            m_jit.loadPtr(
                AssemblyHelpers::addressFor(stackOffset + JSStack::Callee),
                GPRInfo::regT0);
        } else {
            m_jit.move(
                AssemblyHelpers::TrustedImmPtr(inlineCallFrame->calleeRecovery.constant().asCell()),
                GPRInfo::regT0);
        }
        
        if (!inlineCallFrame || inlineCallFrame->isVarargs()) {
            m_jit.load32(
                AssemblyHelpers::payloadFor(stackOffset + JSStack::ArgumentCount),
                GPRInfo::regT1);
        } else {
            m_jit.move(
                AssemblyHelpers::TrustedImm32(inlineCallFrame->arguments.size()),
                GPRInfo::regT1);
        }
        
        m_jit.setupArgumentsWithExecState(
            AssemblyHelpers::TrustedImmPtr(inlineCallFrame), GPRInfo::regT0, GPRInfo::regT1);
        switch (recovery.technique()) {
        case DirectArgumentsThatWereNotCreated:
            m_jit.move(AssemblyHelpers::TrustedImmPtr(bitwise_cast<void*>(operationCreateDirectArgumentsDuringExit)), GPRInfo::nonArgGPR0);
            break;
        case ClonedArgumentsThatWereNotCreated:
            m_jit.move(AssemblyHelpers::TrustedImmPtr(bitwise_cast<void*>(operationCreateClonedArgumentsDuringExit)), GPRInfo::nonArgGPR0);
            break;
        default:
            RELEASE_ASSERT_NOT_REACHED();
            break;
        }
        m_jit.call(GPRInfo::nonArgGPR0);
        m_jit.storeCell(GPRInfo::returnValueGPR, AssemblyHelpers::addressFor(operand));
        
        alreadyAllocatedArguments.add(id, operand);
    }
}