C++ VirtualRegister::offset方法代码示例

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

void CallFrame::setActivation(JSLexicalEnvironment* lexicalEnvironment)
{
    CodeBlock* codeBlock = this->codeBlock();
    RELEASE_ASSERT(codeBlock->needsActivation());
    VirtualRegister activationRegister = codeBlock->activationRegister();
    registers()[activationRegister.offset()] = lexicalEnvironment;
}

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

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());
}

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());
}

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);
}

void BytecodeGeneratorification::run()
{
    // We calculate the liveness at each merge point. This gives us the information which registers should be saved and resumed conservatively.

    {
        GeneratorLivenessAnalysis pass(*this);
        pass.run();
    }

    UnlinkedCodeBlock* codeBlock = m_graph.codeBlock();
    BytecodeRewriter rewriter(m_graph);

    // Setup the global switch for the generator.
    {
        unsigned nextToEnterPoint = enterPoint() + opcodeLength(op_enter);
        unsigned switchTableIndex = m_graph.codeBlock()->numberOfSwitchJumpTables();
        VirtualRegister state = virtualRegisterForArgument(static_cast<int32_t>(JSGeneratorFunction::GeneratorArgument::State));
        auto& jumpTable = m_graph.codeBlock()->addSwitchJumpTable();
        jumpTable.min = 0;
        jumpTable.branchOffsets.resize(m_yields.size() + 1);
        jumpTable.branchOffsets.fill(0);
        jumpTable.add(0, nextToEnterPoint);
        for (unsigned i = 0; i < m_yields.size(); ++i)
            jumpTable.add(i + 1, m_yields[i].point);

        rewriter.insertFragmentBefore(nextToEnterPoint, [&](BytecodeRewriter::Fragment& fragment) {
            fragment.appendInstruction(op_switch_imm, switchTableIndex, nextToEnterPoint, state.offset());
        });
    }

    for (const YieldData& data : m_yields) {
        VirtualRegister scope = virtualRegisterForArgument(static_cast<int32_t>(JSGeneratorFunction::GeneratorArgument::Frame));

        // Emit save sequence.
        rewriter.insertFragmentBefore(data.point, [&](BytecodeRewriter::Fragment& fragment) {
            data.liveness.forEachSetBit([&](size_t index) {
                VirtualRegister operand = virtualRegisterForLocal(index);
                Storage storage = storageForGeneratorLocal(index);

                fragment.appendInstruction(
                    op_put_to_scope,
                    scope.offset(), // scope
                    storage.identifierIndex, // identifier
                    operand.offset(), // value
                    GetPutInfo(DoNotThrowIfNotFound, LocalClosureVar, InitializationMode::NotInitialization).operand(), // info
                    m_generatorFrameSymbolTableIndex, // symbol table constant index
                    storage.scopeOffset.offset() // scope offset
                );
            });

            // Insert op_ret just after save sequence.
            fragment.appendInstruction(op_ret, data.argument);
        });

        // Emit resume sequence.
        rewriter.insertFragmentAfter(data.point, [&](BytecodeRewriter::Fragment& fragment) {
            data.liveness.forEachSetBit([&](size_t index) {
                VirtualRegister operand = virtualRegisterForLocal(index);
                Storage storage = storageForGeneratorLocal(index);

                UnlinkedValueProfile profile = codeBlock->addValueProfile();
                fragment.appendInstruction(
                    op_get_from_scope,
                    operand.offset(), // dst
                    scope.offset(), // scope
                    storage.identifierIndex, // identifier
                    GetPutInfo(DoNotThrowIfNotFound, LocalClosureVar, InitializationMode::NotInitialization).operand(), // info
                    0, // local scope depth
                    storage.scopeOffset.offset(), // scope offset
                    profile // profile
                );
            });
        });

        // Clip the unnecessary bytecodes.
        rewriter.removeBytecode(data.point);
    }

    rewriter.execute();
}

    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.........