C++ codeBlock函数代码示例

Arguments* StackVisitor::Frame::existingArguments()
{
    if (codeBlock()->codeType() != FunctionCode)
        return 0;
    if (!codeBlock()->usesArguments())
        return 0;
    
    VirtualRegister reg;
        
#if ENABLE(DFG_JIT)
    if (isInlinedFrame())
        reg = inlineCallFrame()->argumentsRegister;
    else
#endif // ENABLE(DFG_JIT)
        reg = codeBlock()->argumentsRegister();

    // Care should be taken here since exception fuzzing may raise exceptions in
    // places where they would be otherwise impossible. Therefore, callFrame may
    // lack activation even if the codeBlock signals need of activation. Also,
    // even if codeBlock signals the use of arguments, the
    // unmodifiedArgumentsRegister may not be initialized yet (neither locally
    // nor in lexicalEnvironment).
    JSValue result = jsUndefined();
    if (codeBlock()->needsActivation() && callFrame()->hasActivation())
        result = callFrame()->lexicalEnvironment()->registerAt(unmodifiedArgumentsRegister(reg).offset()).get();
    if (!result || !result.isCell()) // Try local unmodifiedArgumentsRegister if lexicalEnvironment is not present (generally possible) or has not set up registers yet (only possible if fuzzing exceptions).
        result = callFrame()->r(unmodifiedArgumentsRegister(reg).offset()).jsValue();
    if (!result || !result.isCell()) // Protect against the case when exception fuzzing throws when unmodifiedArgumentsRegister is not set up yet (e.g., in op_enter).
        return 0;
    return jsCast<Arguments*>(result);
}

CodeOrigin CallFrame::codeOrigin()
{
    if (!codeBlock())
        return CodeOrigin(0);
#if ENABLE(DFG_JIT)
    if (callSiteBitsAreCodeOriginIndex()) {
        CallSiteIndex index = callSiteIndex();
        ASSERT(codeBlock()->canGetCodeOrigin(index));
        return codeBlock()->codeOrigin(index);
    }
#endif
    return CodeOrigin(callSiteBitsAsBytecodeOffset());
}

CodeOrigin CallFrame::codeOrigin()
{
    if (!codeBlock())
        return CodeOrigin(0);
#if ENABLE(DFG_JIT)
    if (hasLocationAsCodeOriginIndex()) {
        unsigned index = locationAsCodeOriginIndex();
        ASSERT(codeBlock()->canGetCodeOrigin(index));
        return codeBlock()->codeOrigin(index);
    }
#endif
    return CodeOrigin(locationAsBytecodeOffset());
}

CodeBlock* CallFrame::someCodeBlockForPossiblyInlinedCode()
{
    if (!isInlineCallFrame())
        return codeBlock();
    
    return jsCast<FunctionExecutable*>(inlineCallFrame()->executable.get())->baselineCodeBlockFor(
        inlineCallFrame()->isCall ? CodeForCall : CodeForConstruct);
}

 bool isWithinPowerOfTwoForConstant(Node* node)
 {
     JSValue immediateValue = node->valueOfJSConstant(codeBlock());
     if (!immediateValue.isNumber())
         return false;
     double immediate = immediateValue.asNumber();
     return immediate > -(static_cast<int64_t>(1) << power) && immediate < (static_cast<int64_t>(1) << power);
 }

void JITCompiler::compile()
{
    setStartOfCode();
    compileEntry();
    m_speculative = std::make_unique<SpeculativeJIT>(*this);

    // Plant a check that sufficient space is available in the JSStack.
    addPtr(TrustedImm32(virtualRegisterForLocal(m_graph.requiredRegisterCountForExecutionAndExit() - 1).offset() * sizeof(Register)), GPRInfo::callFrameRegister, GPRInfo::regT1);
    Jump stackOverflow = branchPtr(Above, AbsoluteAddress(m_vm->addressOfStackLimit()), GPRInfo::regT1);

    addPtr(TrustedImm32(m_graph.stackPointerOffset() * sizeof(Register)), GPRInfo::callFrameRegister, stackPointerRegister);
    checkStackPointerAlignment();
    compileSetupRegistersForEntry();
    compileEntryExecutionFlag();
    compileBody();
    setEndOfMainPath();

    // === Footer code generation ===
    //
    // Generate the stack overflow handling; if the stack check in the entry head fails,
    // we need to call out to a helper function to throw the StackOverflowError.
    stackOverflow.link(this);

    emitStoreCodeOrigin(CodeOrigin(0));

    if (maxFrameExtentForSlowPathCall)
        addPtr(TrustedImm32(-maxFrameExtentForSlowPathCall), stackPointerRegister);

    m_speculative->callOperationWithCallFrameRollbackOnException(operationThrowStackOverflowError, m_codeBlock);

    // Generate slow path code.
    m_speculative->runSlowPathGenerators(m_pcToCodeOriginMapBuilder);
    m_pcToCodeOriginMapBuilder.appendItem(label(), PCToCodeOriginMapBuilder::defaultCodeOrigin());
    
    compileExceptionHandlers();
    linkOSRExits();
    
    // Create OSR entry trampolines if necessary.
    m_speculative->createOSREntries();
    setEndOfCode();

    auto linkBuffer = std::make_unique<LinkBuffer>(*m_vm, *this, m_codeBlock, JITCompilationCanFail);
    if (linkBuffer->didFailToAllocate()) {
        m_graph.m_plan.finalizer = std::make_unique<FailedFinalizer>(m_graph.m_plan);
        return;
    }
    
    link(*linkBuffer);
    m_speculative->linkOSREntries(*linkBuffer);

    m_jitCode->shrinkToFit();
    codeBlock()->shrinkToFit(CodeBlock::LateShrink);

    disassemble(*linkBuffer);
    
    m_graph.m_plan.finalizer = std::make_unique<JITFinalizer>(
        m_graph.m_plan, m_jitCode.release(), WTFMove(linkBuffer));
}

unsigned CallFrame::bytecodeOffset()
{
    if (!codeBlock())
        return 0;
#if ENABLE(DFG_JIT)
    if (callSiteBitsAreCodeOriginIndex()) {
        ASSERT(codeBlock());
        CodeOrigin codeOrigin = this->codeOrigin();
        for (InlineCallFrame* inlineCallFrame = codeOrigin.inlineCallFrame; inlineCallFrame;) {
            codeOrigin = inlineCallFrame->directCaller;
            inlineCallFrame = codeOrigin.inlineCallFrame;
        }
        return codeOrigin.bytecodeIndex;
    }
#endif
    ASSERT(callSiteBitsAreBytecodeOffset());
    return callSiteBitsAsBytecodeOffset();
}

bool CallFrame::callSiteBitsAreBytecodeOffset() const
{
    ASSERT(codeBlock());
    switch (codeBlock()->jitType()) {
    case JITCode::InterpreterThunk:
    case JITCode::BaselineJIT:
        return true;
    case JITCode::None:
    case JITCode::HostCallThunk:
        RELEASE_ASSERT_NOT_REACHED();
        return false;
    default:
        return false;
    }

    RELEASE_ASSERT_NOT_REACHED();
    return false;
}

    bool run()
    {
        ASSERT(m_graph.m_form == ThreadedCPS);
        ASSERT(m_graph.m_unificationState == GloballyUnified);
        
        ASSERT(codeBlock()->numParameters() >= 1);
        {
            ConcurrentJSLocker locker(profiledBlock()->m_lock);
            
            // We only do this for the arguments at the first block. The arguments from
            // other entrypoints have already been populated with their predictions.
            auto& arguments = m_graph.m_rootToArguments.find(m_graph.block(0))->value;

            for (size_t arg = 0; arg < static_cast<size_t>(codeBlock()->numParameters()); ++arg) {
                ValueProfile& profile = profiledBlock()->valueProfileForArgument(arg);
                arguments[arg]->variableAccessData()->predict(
                    profile.computeUpdatedPrediction(locker));
            }
        }
        
        for (BlockIndex blockIndex = 0; blockIndex < m_graph.numBlocks(); ++blockIndex) {
            BasicBlock* block = m_graph.block(blockIndex);
            if (!block)
                continue;
            if (!block->isOSRTarget)
                continue;
            if (block->bytecodeBegin != m_graph.m_plan.osrEntryBytecodeIndex())
                continue;
            const Operands<Optional<JSValue>>& mustHandleValues = m_graph.m_plan.mustHandleValues();
            for (size_t i = 0; i < mustHandleValues.size(); ++i) {
                int operand = mustHandleValues.operandForIndex(i);
                Optional<JSValue> value = mustHandleValues[i];
                if (!value)
                    continue;
                Node* node = block->variablesAtHead.operand(operand);
                if (!node)
                    continue;
                ASSERT(node->accessesStack(m_graph));
                node->variableAccessData()->predict(speculationFromValue(value.value()));
            }
        }
        
        return true;
    }

bool CallFrame::isInlineCallFrameSlow()
{
    if (!callee())
        return false;
    JSCell* calleeAsFunctionCell = getJSFunction(callee());
    if (!calleeAsFunctionCell)
        return false;
    JSFunction* calleeAsFunction = asFunction(calleeAsFunctionCell);
    return calleeAsFunction->executable() != codeBlock()->ownerExecutable();
}

unsigned CallFrame::bytecodeOffset()
{
    if (!codeBlock())
        return 0;
#if ENABLE(DFG_JIT)
    if (hasLocationAsCodeOriginIndex())
        return bytecodeOffsetFromCodeOriginIndex();
#endif
    return locationAsBytecodeOffset();
}

    bool run()
    {
        ASSERT(m_graph.m_form == ThreadedCPS);
        ASSERT(m_graph.m_unificationState == GloballyUnified);
        
        ASSERT(codeBlock()->numParameters() >= 1);
        for (size_t arg = 0; arg < static_cast<size_t>(codeBlock()->numParameters()); ++arg) {
            ValueProfile* profile = profiledBlock()->valueProfileForArgument(arg);
            if (!profile)
                continue;
            
            m_graph.m_arguments[arg]->variableAccessData()->predict(profile->computeUpdatedPrediction());
            
#if DFG_ENABLE(DEBUG_VERBOSE)
            dataLog(
                "Argument [", arg, "] prediction: ",
                SpeculationDump(m_graph.m_arguments[arg]->variableAccessData()->prediction()), "\n");
#endif
        }
        
        for (BlockIndex blockIndex = 0; blockIndex < m_graph.m_blocks.size(); ++blockIndex) {
            BasicBlock* block = m_graph.m_blocks[blockIndex].get();
            if (!block)
                continue;
            if (!block->isOSRTarget)
                continue;
            if (block->bytecodeBegin != m_graph.m_osrEntryBytecodeIndex)
                continue;
            for (size_t i = 0; i < m_graph.m_mustHandleValues.size(); ++i) {
                Node* node = block->variablesAtHead.operand(
                    m_graph.m_mustHandleValues.operandForIndex(i));
                if (!node)
                    continue;
                ASSERT(node->hasLocal());
                node->variableAccessData()->predict(
                    speculationFromValue(m_graph.m_mustHandleValues[i]));
            }
        }
        
        return true;
    }

StackVisitor::Frame::CodeType StackVisitor::Frame::codeType() const
{
    if (isWasmFrame())
        return CodeType::Wasm;

    if (!codeBlock())
        return CodeType::Native;

    switch (codeBlock()->codeType()) {
    case EvalCode:
        return CodeType::Eval;
    case ModuleCode:
        return CodeType::Module;
    case FunctionCode:
        return CodeType::Function;
    case GlobalCode:
        return CodeType::Global;
    }
    RELEASE_ASSERT_NOT_REACHED();
    return CodeType::Global;
}

Arguments* StackVisitor::Frame::existingArguments()
{
    if (codeBlock()->codeType() != FunctionCode)
        return 0;
    if (!codeBlock()->usesArguments())
        return 0;
    
    VirtualRegister reg;
        
#if ENABLE(DFG_JIT)
    if (isInlinedFrame())
        reg = inlineCallFrame()->argumentsRegister;
    else
#endif // ENABLE(DFG_JIT)
        reg = codeBlock()->argumentsRegister();
    
    JSValue result = callFrame()->r(unmodifiedArgumentsRegister(reg).offset()).jsValue();
    if (!result || !result.isCell()) // Protect against Undefined in case we throw in op_enter.
        return 0;
    return jsCast<Arguments*>(result);
}

StackIterator::Frame::CodeType StackIterator::Frame::codeType() const
{
    if (!isJSFrame())
        return StackIterator::Frame::Native;

    switch (codeBlock()->codeType()) {
    case EvalCode:
        return StackIterator::Frame::Eval;
    case FunctionCode:
        return StackIterator::Frame::Function;
    case GlobalCode:
        return StackIterator::Frame::Global;
    }
    RELEASE_ASSERT_NOT_REACHED();
    return StackIterator::Frame::Global;
}