C++ CCallHelpers::emitExceptionCheck方法代码示例

    CCallHelpers::JumpList generateImpl(AccessGenerationState& state, const RegisterSet& usedRegistersBySnippet, CCallHelpers& jit, std::index_sequence<ArgumentsIndex...>)
    {
        CCallHelpers::JumpList exceptions;
        // We spill (1) the used registers by IC and (2) the used registers by Snippet.
        AccessGenerationState::SpillState spillState = state.preserveLiveRegistersToStackForCall(usedRegistersBySnippet);

        jit.store32(
            CCallHelpers::TrustedImm32(state.callSiteIndexForExceptionHandlingOrOriginal().bits()),
            CCallHelpers::tagFor(static_cast<VirtualRegister>(CallFrameSlot::argumentCount)));

        jit.makeSpaceOnStackForCCall();

        jit.setupArguments<FunctionType>(std::get<ArgumentsIndex>(m_arguments)...);

        CCallHelpers::Call operationCall = jit.call(OperationPtrTag);
        auto function = m_function;
        jit.addLinkTask([=] (LinkBuffer& linkBuffer) {
            linkBuffer.link(operationCall, FunctionPtr<OperationPtrTag>(function));
        });

        jit.setupResults(m_result);
        jit.reclaimSpaceOnStackForCCall();

        CCallHelpers::Jump noException = jit.emitExceptionCheck(state.m_vm, CCallHelpers::InvertedExceptionCheck);

        state.restoreLiveRegistersFromStackForCallWithThrownException(spillState);
        exceptions.append(jit.jump());

        noException.link(&jit);
        RegisterSet dontRestore;
        dontRestore.set(m_result);
        state.restoreLiveRegistersFromStackForCall(spillState, dontRestore);

        return exceptions;
    }

void JSCallVarargs::emit(CCallHelpers& jit, State& state, int32_t spillSlotsOffset, int32_t osrExitFromGenericUnwindSpillSlots)
{
    // We are passed three pieces of information:
    // - The callee.
    // - The arguments object, if it's not a forwarding call.
    // - The "this" value, if it's a constructor call.

    CallVarargsData* data = m_node->callVarargsData();
    
    GPRReg calleeGPR = GPRInfo::argumentGPR0;
    
    GPRReg argumentsGPR = InvalidGPRReg;
    GPRReg thisGPR = InvalidGPRReg;
    
    bool forwarding = false;
    
    switch (m_node->op()) {
    case CallVarargs:
    case TailCallVarargs:
    case TailCallVarargsInlinedCaller:
    case ConstructVarargs:
        argumentsGPR = GPRInfo::argumentGPR1;
        thisGPR = GPRInfo::argumentGPR2;
        break;
    case CallForwardVarargs:
    case TailCallForwardVarargs:
    case TailCallForwardVarargsInlinedCaller:
    case ConstructForwardVarargs:
        thisGPR = GPRInfo::argumentGPR1;
        forwarding = true;
        break;
    default:
        RELEASE_ASSERT_NOT_REACHED();
        break;
    }
    
    const unsigned calleeSpillSlot = 0;
    const unsigned argumentsSpillSlot = 1;
    const unsigned thisSpillSlot = 2;
    const unsigned stackPointerSpillSlot = 3;
    
    // Get some scratch registers.
    RegisterSet usedRegisters;
    usedRegisters.merge(RegisterSet::stackRegisters());
    usedRegisters.merge(RegisterSet::reservedHardwareRegisters());
    usedRegisters.merge(RegisterSet::calleeSaveRegisters());
    usedRegisters.set(calleeGPR);
    if (argumentsGPR != InvalidGPRReg)
        usedRegisters.set(argumentsGPR);
    ASSERT(thisGPR);
    usedRegisters.set(thisGPR);
    ScratchRegisterAllocator allocator(usedRegisters);
    GPRReg scratchGPR1 = allocator.allocateScratchGPR();
    GPRReg scratchGPR2 = allocator.allocateScratchGPR();
    GPRReg scratchGPR3 = allocator.allocateScratchGPR();

    RELEASE_ASSERT(!allocator.numberOfReusedRegisters());
    
    auto computeUsedStack = [&] (GPRReg targetGPR, unsigned extra) {
        if (isARM64()) {
            // Have to do this the weird way because $sp on ARM64 means zero when used in a subtraction.
            jit.move(CCallHelpers::stackPointerRegister, targetGPR);
            jit.negPtr(targetGPR);
            jit.addPtr(GPRInfo::callFrameRegister, targetGPR);
        } else {
            jit.move(GPRInfo::callFrameRegister, targetGPR);
            jit.subPtr(CCallHelpers::stackPointerRegister, targetGPR);
        }
        if (extra)
            jit.subPtr(CCallHelpers::TrustedImm32(extra), targetGPR);
        jit.urshiftPtr(CCallHelpers::Imm32(3), targetGPR);
    };
    
    auto callWithExceptionCheck = [&] (void* callee) {
        jit.move(CCallHelpers::TrustedImmPtr(callee), GPRInfo::nonPreservedNonArgumentGPR);
        jit.call(GPRInfo::nonPreservedNonArgumentGPR);
        m_exceptions.append(jit.emitExceptionCheck(AssemblyHelpers::NormalExceptionCheck, AssemblyHelpers::FarJumpWidth));
    };
    
    if (isARM64()) {
        jit.move(CCallHelpers::stackPointerRegister, scratchGPR1);
        jit.storePtr(scratchGPR1, CCallHelpers::addressFor(spillSlotsOffset + stackPointerSpillSlot));
    } else
        jit.storePtr(CCallHelpers::stackPointerRegister, CCallHelpers::addressFor(spillSlotsOffset + stackPointerSpillSlot));

    unsigned extraStack = sizeof(CallerFrameAndPC) +
        WTF::roundUpToMultipleOf(stackAlignmentBytes(), 5 * sizeof(void*));

    if (forwarding) {
        CCallHelpers::JumpList slowCase;
        computeUsedStack(scratchGPR2, 0);
        emitSetupVarargsFrameFastCase(jit, scratchGPR2, scratchGPR1, scratchGPR2, scratchGPR3, m_node->child2()->origin.semantic.inlineCallFrame, data->firstVarArgOffset, slowCase);
        
        CCallHelpers::Jump done = jit.jump();
        slowCase.link(&jit);
        jit.subPtr(CCallHelpers::TrustedImm32(extraStack), CCallHelpers::stackPointerRegister);
        jit.setupArgumentsExecState();
        callWithExceptionCheck(bitwise_cast<void*>(operationThrowStackOverflowForVarargs));
        jit.abortWithReason(DFGVarargsThrowingPathDidNotThrow);
        
//.........这里部分代码省略.........