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

void JSCallBase::emit(CCallHelpers& jit)
{
    m_callLinkInfo = jit.codeBlock()->addCallLinkInfo();
    
    CCallHelpers::Jump slowPath = jit.branchPtrWithPatch(
        CCallHelpers::NotEqual, GPRInfo::regT0, m_targetToCheck,
        CCallHelpers::TrustedImmPtr(0));
    
    m_fastCall = jit.nearCall();
    CCallHelpers::Jump done = jit.jump();
    
    slowPath.link(&jit);
    
    jit.move(CCallHelpers::TrustedImmPtr(m_callLinkInfo), GPRInfo::regT2);
    m_slowCall = jit.nearCall();
    
    done.link(&jit);
}

void JSCallBase::emit(CCallHelpers& jit, State& /*state*/, int32_t osrExitFromGenericUnwindStackSpillSlot)
{
    RELEASE_ASSERT(!!m_callSiteIndex);

#if FTL_USES_B3
    UNUSED_PARAM(osrExitFromGenericUnwindStackSpillSlot);
#else // FTL_USES_B3
    if (m_correspondingGenericUnwindOSRExit)
        m_correspondingGenericUnwindOSRExit->spillRegistersToSpillSlot(jit, osrExitFromGenericUnwindStackSpillSlot);
#endif // FTL_USES_B3

    jit.store32(CCallHelpers::TrustedImm32(m_callSiteIndex.bits()), CCallHelpers::tagFor(static_cast<VirtualRegister>(JSStack::ArgumentCount)));

    m_callLinkInfo = jit.codeBlock()->addCallLinkInfo();
    
    if (CallLinkInfo::callModeFor(m_type) == CallMode::Tail)
        jit.emitRestoreCalleeSaves();

    CCallHelpers::Jump slowPath = jit.branchPtrWithPatch(
        CCallHelpers::NotEqual, GPRInfo::regT0, m_targetToCheck,
        CCallHelpers::TrustedImmPtr(0));

    CCallHelpers::Jump done;

    if (CallLinkInfo::callModeFor(m_type) == CallMode::Tail) {
        jit.prepareForTailCallSlow();
        m_fastCall = jit.nearTailCall();
    } else {
        m_fastCall = jit.nearCall();
        done = jit.jump();
    }

    slowPath.link(&jit);

    jit.move(CCallHelpers::TrustedImmPtr(m_callLinkInfo), GPRInfo::regT2);
    m_slowCall = jit.nearCall();

    if (CallLinkInfo::callModeFor(m_type) == CallMode::Tail)
        jit.abortWithReason(JITDidReturnFromTailCall);
    else
        done.link(&jit);

    m_callLinkInfo->setUpCall(m_type, m_semanticeOrigin, GPRInfo::regT0);
}

void JSTailCall::emit(JITCode& jitCode, CCallHelpers& jit)
{
    StackMaps::Record* record { nullptr };
    
    for (unsigned i = jitCode.stackmaps.records.size(); i--;) {
        record = &jitCode.stackmaps.records[i];
        if (record->patchpointID == m_stackmapID)
            break;
    }

    RELEASE_ASSERT(record->patchpointID == m_stackmapID);

    m_callLinkInfo = jit.codeBlock()->addCallLinkInfo();

    CallFrameShuffleData shuffleData;

    // The callee was the first passed argument, and must be in a GPR because
    // we used the "anyregcc" calling convention
    auto calleeLocation =
        FTL::Location::forStackmaps(nullptr, record->locations[0]);
    GPRReg calleeGPR = calleeLocation.directGPR();
    shuffleData.callee = ValueRecovery::inGPR(calleeGPR, DataFormatJS);

    // The tag type number was the second argument, if there was one
    auto tagTypeNumberLocation =
        FTL::Location::forStackmaps(&jitCode.stackmaps, record->locations[1]);
    if (tagTypeNumberLocation.isGPR() && !tagTypeNumberLocation.addend())
        shuffleData.tagTypeNumber = tagTypeNumberLocation.directGPR();

    shuffleData.args.grow(numArguments());
    HashMap<Reg, Vector<std::pair<ValueRecovery*, int32_t>>> withAddend;
    size_t numAddends { 0 };
    for (size_t i = 0; i < numArguments(); ++i) {
        shuffleData.args[i] = recoveryFor(m_arguments[i], *record, jitCode.stackmaps);
        if (FTL::Location addend = getRegisterWithAddend(m_arguments[i], *record, jitCode.stackmaps)) {
            withAddend.add(
                addend.reg(),
                Vector<std::pair<ValueRecovery*, int32_t>>()).iterator->value.append(
                    std::make_pair(&shuffleData.args[i], addend.addend()));
            numAddends++;
        }
    }

    numAddends = WTF::roundUpToMultipleOf(stackAlignmentRegisters(), numAddends);

    shuffleData.numLocals = static_cast<int64_t>(jitCode.stackmaps.stackSizeForLocals()) / sizeof(void*) + numAddends;

    ASSERT(!numAddends == withAddend.isEmpty());

    if (!withAddend.isEmpty()) {
        jit.subPtr(MacroAssembler::TrustedImm32(numAddends * sizeof(void*)), MacroAssembler::stackPointerRegister);
        VirtualRegister spillBase { 1 - static_cast<int>(shuffleData.numLocals) };
        for (auto entry : withAddend) {
            for (auto pair : entry.value) {
                ASSERT(numAddends > 0);
                VirtualRegister spillSlot { spillBase + --numAddends };
                ASSERT(entry.key.isGPR());
                jit.addPtr(MacroAssembler::TrustedImm32(pair.second), entry.key.gpr());
                jit.storePtr(entry.key.gpr(), CCallHelpers::addressFor(spillSlot));
                jit.subPtr(MacroAssembler::TrustedImm32(pair.second), entry.key.gpr());
                *pair.first = ValueRecovery::displacedInJSStack(spillSlot, pair.first->dataFormat());
            }
        }
        ASSERT(numAddends < stackAlignmentRegisters());
    }

    shuffleData.args.resize(numArguments());
    for (size_t i = 0; i < numArguments(); ++i)
        shuffleData.args[i] = recoveryFor(m_arguments[i], *record, jitCode.stackmaps);

    shuffleData.setupCalleeSaveRegisters(jit.codeBlock());

    CCallHelpers::Jump slowPath = jit.branchPtrWithPatch(
        CCallHelpers::NotEqual, calleeGPR, m_targetToCheck,
        CCallHelpers::TrustedImmPtr(0));

    m_callLinkInfo->setFrameShuffleData(shuffleData);
    CallFrameShuffler(jit, shuffleData).prepareForTailCall();

    m_fastCall = jit.nearTailCall();

    slowPath.link(&jit);

    CallFrameShuffler slowPathShuffler(jit, shuffleData);
    slowPathShuffler.setCalleeJSValueRegs(JSValueRegs { GPRInfo::regT0 });
    slowPathShuffler.prepareForSlowPath();

    jit.move(CCallHelpers::TrustedImmPtr(m_callLinkInfo), GPRInfo::regT2);

    m_slowCall = jit.nearCall();

    jit.abortWithReason(JITDidReturnFromTailCall);

    m_callLinkInfo->setUpCall(m_type, m_semanticeOrigin, calleeGPR);
}