C++ CCallHelpers类代码示例

void MethodOfGettingAValueProfile::emitReportValue(CCallHelpers& jit, JSValueRegs regs) const
{
    switch (m_kind) {
    case None:
        return;
        
    case Ready:
        jit.storeValue(regs, u.profile->specFailBucket(0));
        return;
        
    case LazyOperand: {
        LazyOperandValueProfileKey key(u.lazyOperand.bytecodeOffset, VirtualRegister(u.lazyOperand.operand));
        
        ConcurrentJSLocker locker(u.lazyOperand.codeBlock->m_lock);
        LazyOperandValueProfile* profile =
            u.lazyOperand.codeBlock->lazyOperandValueProfiles(locker).add(locker, key);
        jit.storeValue(regs, profile->specFailBucket(0));
        return;
    }
        
    case ArithProfileReady: {
        u.arithProfile->emitObserveResult(jit, regs, DoNotHaveTagRegisters);
        return;
    } }
    
    RELEASE_ASSERT_NOT_REACHED();
}

void emitSetVarargsFrame(CCallHelpers& jit, GPRReg lengthGPR, bool lengthIncludesThis, GPRReg numUsedSlotsGPR, GPRReg resultGPR)
{
    jit.move(numUsedSlotsGPR, resultGPR);
    // We really want to make sure the size of the new call frame is a multiple of
    // stackAlignmentRegisters(), however it is easier to accomplish this by
    // rounding numUsedSlotsGPR to the next multiple of stackAlignmentRegisters().
    // Together with the rounding below, we will assure that the new call frame is
    // located on a stackAlignmentRegisters() boundary and a multiple of
    // stackAlignmentRegisters() in size.
    jit.addPtr(CCallHelpers::TrustedImm32(stackAlignmentRegisters() - 1), resultGPR);
    jit.andPtr(CCallHelpers::TrustedImm32(~(stackAlignmentRegisters() - 1)), resultGPR);

    jit.addPtr(lengthGPR, resultGPR);
    jit.addPtr(CCallHelpers::TrustedImm32(JSStack::CallFrameHeaderSize + (lengthIncludesThis? 0 : 1)), resultGPR);
    
    // resultGPR now has the required frame size in Register units
    // Round resultGPR to next multiple of stackAlignmentRegisters()
    jit.addPtr(CCallHelpers::TrustedImm32(stackAlignmentRegisters() - 1), resultGPR);
    jit.andPtr(CCallHelpers::TrustedImm32(~(stackAlignmentRegisters() - 1)), resultGPR);
    
    // Now resultGPR has the right stack frame offset in Register units.
    jit.negPtr(resultGPR);
    jit.lshiftPtr(CCallHelpers::Imm32(3), resultGPR);
    jit.addPtr(GPRInfo::callFrameRegister, resultGPR);
}

void BasicBlockLocation::emitExecuteCode(CCallHelpers& jit, MacroAssembler::RegisterID scratch) const
{
    static_assert(sizeof(size_t) == 4, "Assuming size_t is 32 bits on 32 bit platforms.");
    jit.load32(&m_executionCount, scratch);
    CCallHelpers::Jump done = jit.branchAdd32(CCallHelpers::Zero, scratch, CCallHelpers::TrustedImm32(1), scratch);
    jit.store32(scratch, bitwise_cast<void*>(&m_executionCount));
    done.link(&jit);
}

static void dispatch(CCallHelpers& jit, FTL::State* state, const B3::StackmapGenerationParams& params, DFG::Node* node, Box<CCallHelpers::JumpList> exceptions, CCallHelpers::JumpList from, OperationType operation, ResultType result, Arguments arguments, std::index_sequence<ArgumentsIndex...>)
{
    CCallHelpers::Label done = jit.label();
    params.addLatePath([=] (CCallHelpers& jit) {
        AllowMacroScratchRegisterUsage allowScratch(jit);

        from.link(&jit);
        callOperation(
            *state, params.unavailableRegisters(), jit, node->origin.semantic,
            exceptions.get(), operation, extractResult(result), std::get<ArgumentsIndex>(arguments)...);
        jit.jump().linkTo(done, &jit);
    });
}

inline void emitPointerValidation(CCallHelpers& jit, GPRReg pointerGPR)
{
#if !ASSERT_DISABLED
    CCallHelpers::Jump isNonZero = jit.branchTestPtr(CCallHelpers::NonZero, pointerGPR);
    jit.breakpoint();
    isNonZero.link(&jit);
    jit.push(pointerGPR);
    jit.load8(pointerGPR, pointerGPR);
    jit.pop(pointerGPR);
#else
    UNUSED_PARAM(jit);
    UNUSED_PARAM(pointerGPR);
#endif
}

    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 ArithProfile::emitObserveResult(CCallHelpers& jit, JSValueRegs regs, TagRegistersMode mode)
{
    if (!shouldEmitSetDouble() && !shouldEmitSetNonNumber())
        return;

    CCallHelpers::Jump isInt32 = jit.branchIfInt32(regs, mode);
    CCallHelpers::Jump notDouble = jit.branchIfNotDoubleKnownNotInt32(regs, mode);
    emitSetDouble(jit);
    CCallHelpers::Jump done = jit.jump();
    notDouble.link(&jit);
    emitSetNonNumber(jit);
    done.link(&jit);
    isInt32.link(&jit);
}

 CCallHelpers::JumpList generate(AccessGenerationState& state, const RegisterSet& usedRegistersBySnippet, CCallHelpers& jit) override
 {
     m_from.link(&jit);
     CCallHelpers::JumpList exceptions = generateImpl(state, usedRegistersBySnippet, jit, std::make_index_sequence<std::tuple_size<std::tuple<Arguments...>>::value>());
     jit.jump().linkTo(m_to, &jit);
     return exceptions;
 }

Box<CCallHelpers::JumpList> ExceptionTarget::jumps(CCallHelpers& jit)
{
    Box<CCallHelpers::JumpList> result = Box<CCallHelpers::JumpList>::create();
    if (m_isDefaultHandler) {
        Box<CCallHelpers::Label> defaultHandler = m_defaultHandler;
        jit.addLinkTask(
            [=] (LinkBuffer& linkBuffer) {
                linkBuffer.link(*result, linkBuffer.locationOf(*defaultHandler));
            });
    } else {
        RefPtr<OSRExitHandle> handle = m_handle;
        jit.addLinkTask(
            [=] (LinkBuffer& linkBuffer) {
                linkBuffer.link(*result, linkBuffer.locationOf(handle->label));
            });
    }
    return result;
}

void storeCodeOrigin(State& state, CCallHelpers& jit, CodeOrigin codeOrigin)
{
    if (!codeOrigin.isSet())
        return;
    
    unsigned index = state.jitCode->common.addCodeOrigin(codeOrigin);
    unsigned locationBits = CallFrame::Location::encodeAsCodeOriginIndex(index);
    jit.store32(
        CCallHelpers::TrustedImm32(locationBits),
        CCallHelpers::tagFor(static_cast<VirtualRegister>(JSStack::ArgumentCount)));
}

void OSRExitHandle::emitExitThunk(State& state, CCallHelpers& jit)
{
    Profiler::Compilation* compilation = state.graph.compilation();
    CCallHelpers::Label myLabel = jit.label();
    label = myLabel;
    jit.pushToSaveImmediateWithoutTouchingRegisters(CCallHelpers::TrustedImm32(index));
    CCallHelpers::PatchableJump jump = jit.patchableJump();
    RefPtr<OSRExitHandle> self = this;
    VM& vm = state.vm();
    jit.addLinkTask(
        [self, jump, myLabel, compilation, &vm] (LinkBuffer& linkBuffer) {
            self->exit.m_patchableJump = CodeLocationJump<JSInternalPtrTag>(linkBuffer.locationOf<JSInternalPtrTag>(jump));

            linkBuffer.link(
                jump.m_jump,
                CodeLocationLabel<JITThunkPtrTag>(vm.getCTIStub(osrExitGenerationThunkGenerator).code()));
            if (compilation)
                compilation->addOSRExitSite({ linkBuffer.locationOf<JSInternalPtrTag>(myLabel) });
        });
}

CCallHelpers::Jump CCallSpecial::generate(Inst& inst, CCallHelpers& jit, GenerationContext&)
{
    switch (inst.args[calleeArgOffset].kind()) {
    case Arg::Imm:
    case Arg::Imm64:
        jit.move(inst.args[calleeArgOffset].asTrustedImmPtr(), scratchRegister);
        jit.call(scratchRegister);
        break;
    case Arg::Tmp:
        jit.call(inst.args[calleeArgOffset].gpr());
        break;
    case Arg::Addr:
        jit.call(inst.args[calleeArgOffset].asAddress());
        break;
    default:
        RELEASE_ASSERT_NOT_REACHED();
        break;
    }
    return CCallHelpers::Jump();
}

void adjustAndJumpToTarget(CCallHelpers& jit, const OSRExitBase& exit)
{
    if (exit.m_codeOrigin.inlineCallFrame)
        jit.addPtr(AssemblyHelpers::TrustedImm32(exit.m_codeOrigin.inlineCallFrame->stackOffset * sizeof(EncodedJSValue)), GPRInfo::callFrameRegister);

    CodeBlock* baselineCodeBlock = jit.baselineCodeBlockFor(exit.m_codeOrigin);
    Vector<BytecodeAndMachineOffset>& decodedCodeMap = jit.decodedCodeMapFor(baselineCodeBlock);
    
    BytecodeAndMachineOffset* mapping = binarySearch<BytecodeAndMachineOffset, unsigned>(decodedCodeMap, decodedCodeMap.size(), exit.m_codeOrigin.bytecodeIndex, BytecodeAndMachineOffset::getBytecodeIndex);
    
    ASSERT(mapping);
    ASSERT(mapping->m_bytecodeIndex == exit.m_codeOrigin.bytecodeIndex);
    
    void* jumpTarget = baselineCodeBlock->jitCode()->executableAddressAtOffset(mapping->m_machineCodeOffset);
    
    jit.move(AssemblyHelpers::TrustedImmPtr(jumpTarget), GPRInfo::regT2);
    jit.jump(GPRInfo::regT2);

#if DFG_ENABLE(DEBUG_VERBOSE)
    dataLogF("   -> %p\n", jumpTarget);
#endif
}

MacroAssembler::Call callOperation(
    State& state, const RegisterSet& usedRegisters, CCallHelpers& jit, 
    CodeOrigin codeOrigin, MacroAssembler::JumpList* exceptionTarget,
    V_JITOperation_ESsiJJI operation, StructureStubInfo* stubInfo, GPRReg value,
    GPRReg object, StringImpl* uid)
{
    storeCodeOrigin(state, jit, codeOrigin);
    CallContext context(state, usedRegisters, jit, 5, InvalidGPRReg);
    jit.setupArgumentsWithExecState(
        CCallHelpers::TrustedImmPtr(stubInfo), value, object,
        CCallHelpers::TrustedImmPtr(uid));
    return context.makeCall(bitwise_cast<void*>(operation), exceptionTarget);
}

bool JITNegGenerator::generateFastPath(CCallHelpers& jit, CCallHelpers::JumpList& endJumpList, CCallHelpers::JumpList& slowPathJumpList, const ArithProfile* arithProfile, bool shouldEmitProfiling)
{
    ASSERT(m_scratchGPR != m_src.payloadGPR());
    ASSERT(m_scratchGPR != m_result.payloadGPR());
    ASSERT(m_scratchGPR != InvalidGPRReg);
#if USE(JSVALUE32_64)
    ASSERT(m_scratchGPR != m_src.tagGPR());
    ASSERT(m_scratchGPR != m_result.tagGPR());
#endif

    jit.moveValueRegs(m_src, m_result);
    CCallHelpers::Jump srcNotInt = jit.branchIfNotInt32(m_src);

    // -0 should produce a double, and hence cannot be negated as an int.
    // The negative int32 0x80000000 doesn't have a positive int32 representation, and hence cannot be negated as an int.
    slowPathJumpList.append(jit.branchTest32(CCallHelpers::Zero, m_src.payloadGPR(), CCallHelpers::TrustedImm32(0x7fffffff)));

    jit.neg32(m_result.payloadGPR());
#if USE(JSVALUE64)
    jit.boxInt32(m_result.payloadGPR(), m_result);
#endif
    endJumpList.append(jit.jump());

    srcNotInt.link(&jit);
    slowPathJumpList.append(jit.branchIfNotNumber(m_src, m_scratchGPR));

    // For a double, all we need to do is to invert the sign bit.
#if USE(JSVALUE64)
    jit.move(CCallHelpers::TrustedImm64((int64_t)(1ull << 63)), m_scratchGPR);
    jit.xor64(m_scratchGPR, m_result.payloadGPR());
#else
    jit.xor32(CCallHelpers::TrustedImm32(1 << 31), m_result.tagGPR());
#endif
    // The flags of ArithNegate are basic in DFG.
    // We only need to know if we ever produced a number.
    if (shouldEmitProfiling && arithProfile && !arithProfile->lhsObservedType().sawNumber() && !arithProfile->didObserveDouble())
        arithProfile->emitSetDouble(jit);
    return true;
}