C++ Jump::link方法代码示例

MacroAssemblerCodePtr powThunkGenerator(JSGlobalData* globalData, ExecutablePool* pool)
{
#if USE(JSVALUE64) || USE(JSVALUE32_64)
    SpecializedThunkJIT jit(2, globalData, pool);
    if (!jit.supportsFloatingPoint())
        return globalData->jitStubs->ctiNativeCall();

    jit.loadDouble(&oneConstant, SpecializedThunkJIT::fpRegT1);
    jit.loadDoubleArgument(0, SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::regT0);
    MacroAssembler::Jump nonIntExponent;
    jit.loadInt32Argument(1, SpecializedThunkJIT::regT0, nonIntExponent);
    jit.appendFailure(jit.branch32(MacroAssembler::LessThan, SpecializedThunkJIT::regT0, MacroAssembler::Imm32(0)));
    
    MacroAssembler::Jump exponentIsZero = jit.branchTest32(MacroAssembler::Zero, SpecializedThunkJIT::regT0);
    MacroAssembler::Label startLoop(jit.label());

    MacroAssembler::Jump exponentIsEven = jit.branchTest32(MacroAssembler::Zero, SpecializedThunkJIT::regT0, MacroAssembler::Imm32(1));
    jit.mulDouble(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::fpRegT1);
    exponentIsEven.link(&jit);
    jit.mulDouble(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::fpRegT0);
    jit.rshift32(MacroAssembler::Imm32(1), SpecializedThunkJIT::regT0);
    jit.branchTest32(MacroAssembler::NonZero, SpecializedThunkJIT::regT0).linkTo(startLoop, &jit);

    exponentIsZero.link(&jit);

    {
        SpecializedThunkJIT::JumpList doubleResult;
        jit.branchConvertDoubleToInt32(SpecializedThunkJIT::fpRegT1, SpecializedThunkJIT::regT0, doubleResult, SpecializedThunkJIT::fpRegT0);
        jit.returnInt32(SpecializedThunkJIT::regT0);
        doubleResult.link(&jit);
        jit.returnDouble(SpecializedThunkJIT::fpRegT1);
    }

    if (jit.supportsFloatingPointSqrt()) {
        nonIntExponent.link(&jit);
        jit.loadDouble(&negativeHalfConstant, SpecializedThunkJIT::fpRegT3);
        jit.loadDoubleArgument(1, SpecializedThunkJIT::fpRegT2, SpecializedThunkJIT::regT0);
        jit.appendFailure(jit.branchDouble(MacroAssembler::DoubleLessThanOrEqual, SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::fpRegT1));
        jit.appendFailure(jit.branchDouble(MacroAssembler::DoubleNotEqualOrUnordered, SpecializedThunkJIT::fpRegT2, SpecializedThunkJIT::fpRegT3));
        jit.sqrtDouble(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::fpRegT0);
        jit.divDouble(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::fpRegT1);

        SpecializedThunkJIT::JumpList doubleResult;
        jit.branchConvertDoubleToInt32(SpecializedThunkJIT::fpRegT1, SpecializedThunkJIT::regT0, doubleResult, SpecializedThunkJIT::fpRegT0);
        jit.returnInt32(SpecializedThunkJIT::regT0);
        doubleResult.link(&jit);
        jit.returnDouble(SpecializedThunkJIT::fpRegT1);
    } else
        jit.appendFailure(nonIntExponent);

    return jit.finalize(globalData->jitStubs->ctiNativeCall());
#else
    UNUSED_PARAM(pool);
    return globalData->jitStubs->ctiNativeCall();
#endif
}

void AssemblyHelpers::purifyNaN(FPRReg fpr)
{
    MacroAssembler::Jump notNaN = branchDouble(DoubleEqual, fpr, fpr);
    static const double NaN = PNaN;
    loadDouble(TrustedImmPtr(&NaN), fpr);
    notNaN.link(this);
}

MacroAssemblerCodeRef osrEntryThunkGenerator(VM* vm)
{
    AssemblyHelpers jit(nullptr);

    // We get passed the address of a scratch buffer. The first 8-byte slot of the buffer
    // is the frame size. The second 8-byte slot is the pointer to where we are supposed to
    // jump. The remaining bytes are the new call frame header followed by the locals.

    ptrdiff_t offsetOfFrameSize = 0; // This is the DFG frame count.
    ptrdiff_t offsetOfTargetPC = offsetOfFrameSize + sizeof(EncodedJSValue);
    ptrdiff_t offsetOfPayload = offsetOfTargetPC + sizeof(EncodedJSValue);
    ptrdiff_t offsetOfLocals = offsetOfPayload + sizeof(Register) * CallFrame::headerSizeInRegisters;

    jit.move(GPRInfo::returnValueGPR2, GPRInfo::regT0);
    jit.loadPtr(MacroAssembler::Address(GPRInfo::regT0, offsetOfFrameSize), GPRInfo::regT1); // Load the frame size.
    jit.move(GPRInfo::regT1, GPRInfo::regT2);
    jit.lshiftPtr(MacroAssembler::Imm32(3), GPRInfo::regT2);
    jit.move(GPRInfo::callFrameRegister, MacroAssembler::stackPointerRegister);
    jit.subPtr(GPRInfo::regT2, MacroAssembler::stackPointerRegister);

    MacroAssembler::Label loop = jit.label();
    jit.subPtr(MacroAssembler::TrustedImm32(1), GPRInfo::regT1);
    jit.move(GPRInfo::regT1, GPRInfo::regT4);
    jit.negPtr(GPRInfo::regT4);
    jit.load32(MacroAssembler::BaseIndex(GPRInfo::regT0, GPRInfo::regT1, MacroAssembler::TimesEight, offsetOfLocals), GPRInfo::regT2);
    jit.load32(MacroAssembler::BaseIndex(GPRInfo::regT0, GPRInfo::regT1, MacroAssembler::TimesEight, offsetOfLocals + sizeof(int32_t)), GPRInfo::regT3);
    jit.store32(GPRInfo::regT2, MacroAssembler::BaseIndex(GPRInfo::callFrameRegister, GPRInfo::regT4, MacroAssembler::TimesEight, -static_cast<intptr_t>(sizeof(Register))));
    jit.store32(GPRInfo::regT3, MacroAssembler::BaseIndex(GPRInfo::callFrameRegister, GPRInfo::regT4, MacroAssembler::TimesEight, -static_cast<intptr_t>(sizeof(Register)) + static_cast<intptr_t>(sizeof(int32_t))));
    jit.branchPtr(MacroAssembler::NotEqual, GPRInfo::regT1, MacroAssembler::TrustedImmPtr(bitwise_cast<void*>(-static_cast<intptr_t>(CallFrame::headerSizeInRegisters)))).linkTo(loop, &jit);

    jit.loadPtr(MacroAssembler::Address(GPRInfo::regT0, offsetOfTargetPC), GPRInfo::regT1);
    MacroAssembler::Jump ok = jit.branchPtr(MacroAssembler::Above, GPRInfo::regT1, MacroAssembler::TrustedImmPtr(bitwise_cast<void*>(static_cast<intptr_t>(1000))));
    jit.abortWithReason(DFGUnreasonableOSREntryJumpDestination);

    ok.link(&jit);
    jit.restoreCalleeSavesFromVMEntryFrameCalleeSavesBuffer(*vm);
    jit.emitMaterializeTagCheckRegisters();

    jit.jump(GPRInfo::regT1);

    LinkBuffer patchBuffer(jit, GLOBAL_THUNK_ID);
    return FINALIZE_CODE(patchBuffer, ("DFG OSR entry thunk"));
}

MacroAssemblerCodeRef clz32ThunkGenerator(VM* vm)
{
    SpecializedThunkJIT jit(vm, 1);
    MacroAssembler::Jump nonIntArgJump;
    jit.loadInt32Argument(0, SpecializedThunkJIT::regT0, nonIntArgJump);

    SpecializedThunkJIT::Label convertedArgumentReentry(&jit);
    jit.countLeadingZeros32(SpecializedThunkJIT::regT0, SpecializedThunkJIT::regT1);
    jit.returnInt32(SpecializedThunkJIT::regT1);

    if (jit.supportsFloatingPointTruncate()) {
        nonIntArgJump.link(&jit);
        jit.loadDoubleArgument(0, SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::regT0);
        jit.branchTruncateDoubleToInt32(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::regT0, SpecializedThunkJIT::BranchIfTruncateSuccessful).linkTo(convertedArgumentReentry, &jit);
        jit.appendFailure(jit.jump());
    } else
        jit.appendFailure(nonIntArgJump);

    return jit.finalize(vm->jitStubs->ctiNativeTailCall(vm), "clz32");
}

MacroAssemblerCodeRef floorThunkGenerator(VM* vm)
{
    SpecializedThunkJIT jit(vm, 1);
    MacroAssembler::Jump nonIntJump;
    if (!UnaryDoubleOpWrapper(floor) || !jit.supportsFloatingPoint())
        return MacroAssemblerCodeRef::createSelfManagedCodeRef(vm->jitStubs->ctiNativeCall(vm));
    jit.loadInt32Argument(0, SpecializedThunkJIT::regT0, nonIntJump);
    jit.returnInt32(SpecializedThunkJIT::regT0);
    nonIntJump.link(&jit);
    jit.loadDoubleArgument(0, SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::regT0);
#if CPU(ARM64)
    SpecializedThunkJIT::JumpList doubleResult;
    jit.floorDouble(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::fpRegT0);
    jit.branchConvertDoubleToInt32(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::regT0, doubleResult, SpecializedThunkJIT::fpRegT1);
    jit.returnInt32(SpecializedThunkJIT::regT0);
    doubleResult.link(&jit);
    jit.returnDouble(SpecializedThunkJIT::fpRegT0);
#else
    SpecializedThunkJIT::Jump intResult;
    SpecializedThunkJIT::JumpList doubleResult;
    if (jit.supportsFloatingPointTruncate()) {
        jit.loadDouble(&zeroConstant, SpecializedThunkJIT::fpRegT1);
        doubleResult.append(jit.branchDouble(MacroAssembler::DoubleEqual, SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::fpRegT1));
        SpecializedThunkJIT::JumpList slowPath;
        // Handle the negative doubles in the slow path for now.
        slowPath.append(jit.branchDouble(MacroAssembler::DoubleLessThanOrUnordered, SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::fpRegT1));
        slowPath.append(jit.branchTruncateDoubleToInt32(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::regT0));
        intResult = jit.jump();
        slowPath.link(&jit);
    }
    jit.callDoubleToDoublePreservingReturn(UnaryDoubleOpWrapper(floor));
    jit.branchConvertDoubleToInt32(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::regT0, doubleResult, SpecializedThunkJIT::fpRegT1);
    if (jit.supportsFloatingPointTruncate())
        intResult.link(&jit);
    jit.returnInt32(SpecializedThunkJIT::regT0);
    doubleResult.link(&jit);
    jit.returnDouble(SpecializedThunkJIT::fpRegT0);
#endif // CPU(ARM64)
    return jit.finalize(vm->jitStubs->ctiNativeTailCall(vm), "floor");
}

MacroAssemblerCodeRef ceilThunkGenerator(VM* vm)
{
    SpecializedThunkJIT jit(vm, 1);
    if (!UnaryDoubleOpWrapper(ceil) || !jit.supportsFloatingPoint())
        return MacroAssemblerCodeRef::createSelfManagedCodeRef(vm->jitStubs->ctiNativeCall(vm));
    MacroAssembler::Jump nonIntJump;
    jit.loadInt32Argument(0, SpecializedThunkJIT::regT0, nonIntJump);
    jit.returnInt32(SpecializedThunkJIT::regT0);
    nonIntJump.link(&jit);
    jit.loadDoubleArgument(0, SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::regT0);
#if CPU(ARM64)
    jit.ceilDouble(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::fpRegT0);
#else
    jit.callDoubleToDoublePreservingReturn(UnaryDoubleOpWrapper(ceil));
#endif // CPU(ARM64)
    SpecializedThunkJIT::JumpList doubleResult;
    jit.branchConvertDoubleToInt32(SpecializedThunkJIT::fpRegT0, SpecializedThunkJIT::regT0, doubleResult, SpecializedThunkJIT::fpRegT1);
    jit.returnInt32(SpecializedThunkJIT::regT0);
    doubleResult.link(&jit);
    jit.returnDouble(SpecializedThunkJIT::fpRegT0);
    return jit.finalize(vm->jitStubs->ctiNativeTailCall(vm), "ceil");
}

    MacroAssemblerCodeRef jitWriteThunkGenerator(void* writableAddr, void* stubBase, size_t stubSize)
    {
        using namespace ARM64Registers;
        using TrustedImm32 = MacroAssembler::TrustedImm32;

        MacroAssembler jit;

        jit.move(MacroAssembler::TrustedImmPtr(writableAddr), x7);
        jit.addPtr(x7, x0);

        jit.move(x0, x3);
        MacroAssembler::Jump smallCopy = jit.branch64(MacroAssembler::Below, x2, MacroAssembler::TrustedImm64(64));

        jit.add64(TrustedImm32(32), x3);
        jit.and64(TrustedImm32(-32), x3);
        jit.loadPair64(x1, x12, x13);
        jit.loadPair64(x1, TrustedImm32(16), x14, x15);
        jit.sub64(x3, x0, x5);
        jit.addPtr(x5, x1);

        jit.loadPair64(x1, x8, x9);
        jit.loadPair64(x1, TrustedImm32(16), x10, x11);
        jit.add64(TrustedImm32(32), x1);
        jit.sub64(x5, x2);
        jit.storePair64(x12, x13, x0);
        jit.storePair64(x14, x15, x0, TrustedImm32(16));
        MacroAssembler::Jump cleanup = jit.branchSub64(MacroAssembler::BelowOrEqual, TrustedImm32(64), x2);

        MacroAssembler::Label copyLoop = jit.label();
        jit.storePair64WithNonTemporalAccess(x8, x9, x3);
        jit.storePair64WithNonTemporalAccess(x10, x11, x3, TrustedImm32(16));
        jit.add64(TrustedImm32(32), x3);
        jit.loadPair64WithNonTemporalAccess(x1, x8, x9);
        jit.loadPair64WithNonTemporalAccess(x1, TrustedImm32(16), x10, x11);
        jit.add64(TrustedImm32(32), x1);
        jit.branchSub64(MacroAssembler::Above, TrustedImm32(32), x2).linkTo(copyLoop, &jit);

        cleanup.link(&jit);
        jit.add64(x2, x1);
        jit.loadPair64(x1, x12, x13);
        jit.loadPair64(x1, TrustedImm32(16), x14, x15);
        jit.storePair64(x8, x9, x3);
        jit.storePair64(x10, x11, x3, TrustedImm32(16));
        jit.addPtr(x2, x3);
        jit.storePair64(x12, x13, x3, TrustedImm32(32));
        jit.storePair64(x14, x15, x3, TrustedImm32(48));
        jit.ret();

        MacroAssembler::Label local0 = jit.label();
        jit.load64(x1, PostIndex(8), x6);
        jit.store64(x6, x3, PostIndex(8));
        smallCopy.link(&jit);
        jit.branchSub64(MacroAssembler::AboveOrEqual, TrustedImm32(8), x2).linkTo(local0, &jit);
        MacroAssembler::Jump local2 = jit.branchAdd64(MacroAssembler::Equal, TrustedImm32(8), x2);
        MacroAssembler::Label local1 = jit.label();
        jit.load8(x1, PostIndex(1), x6);
        jit.store8(x6, x3, PostIndex(1));
        jit.branchSub64(MacroAssembler::NotEqual, TrustedImm32(1), x2).linkTo(local1, &jit);
        local2.link(&jit);
        jit.ret();

        LinkBuffer linkBuffer(jit, stubBase, stubSize);
        return FINALIZE_CODE(linkBuffer, ("Bulletproof JIT write thunk"));
    }

//.........这里部分代码省略.........
            MacroAssembler::Address(MacroAssembler::framePointerRegister, entry.offset()),
            GPRInfo::regT0);
        jit.store64(GPRInfo::regT0, unwindScratch + i);
    }
    
    jit.load32(CCallHelpers::payloadFor(JSStack::ArgumentCount), GPRInfo::regT2);
    
    // Let's say that the FTL function had failed its arity check. In that case, the stack will
    // contain some extra stuff.
    //
    // We compute the padded stack space:
    //
    //     paddedStackSpace = roundUp(codeBlock->numParameters - regT2 + 1)
    //
    // The stack will have regT2 + CallFrameHeaderSize stuff.
    // We want to make the stack look like this, from higher addresses down:
    //
    //     - argument padding
    //     - actual arguments
    //     - call frame header

    // This code assumes that we're dealing with FunctionCode.
    RELEASE_ASSERT(codeBlock->codeType() == FunctionCode);
    
    jit.add32(
        MacroAssembler::TrustedImm32(-codeBlock->numParameters()), GPRInfo::regT2,
        GPRInfo::regT3);
    MacroAssembler::Jump arityIntact = jit.branch32(
        MacroAssembler::GreaterThanOrEqual, GPRInfo::regT3, MacroAssembler::TrustedImm32(0));
    jit.neg32(GPRInfo::regT3);
    jit.add32(MacroAssembler::TrustedImm32(1 + stackAlignmentRegisters() - 1), GPRInfo::regT3);
    jit.and32(MacroAssembler::TrustedImm32(-stackAlignmentRegisters()), GPRInfo::regT3);
    jit.add32(GPRInfo::regT3, GPRInfo::regT2);
    arityIntact.link(&jit);

    CodeBlock* baselineCodeBlock = jit.baselineCodeBlockFor(exit.m_codeOrigin);

    // First set up SP so that our data doesn't get clobbered by signals.
    unsigned conservativeStackDelta =
        (exit.m_values.numberOfLocals() + baselineCodeBlock->calleeSaveSpaceAsVirtualRegisters()) * sizeof(Register) +
        maxFrameExtentForSlowPathCall;
    conservativeStackDelta = WTF::roundUpToMultipleOf(
        stackAlignmentBytes(), conservativeStackDelta);
    jit.addPtr(
        MacroAssembler::TrustedImm32(-conservativeStackDelta),
        MacroAssembler::framePointerRegister, MacroAssembler::stackPointerRegister);
    jit.checkStackPointerAlignment();

    RegisterSet allFTLCalleeSaves = RegisterSet::ftlCalleeSaveRegisters();
    RegisterAtOffsetList* baselineCalleeSaves = baselineCodeBlock->calleeSaveRegisters();

    for (Reg reg = Reg::first(); reg <= Reg::last(); reg = reg.next()) {
        if (!allFTLCalleeSaves.get(reg))
            continue;
        unsigned unwindIndex = codeBlock->calleeSaveRegisters()->indexOf(reg);
        RegisterAtOffset* baselineRegisterOffset = baselineCalleeSaves->find(reg);

        if (reg.isGPR()) {
            GPRReg regToLoad = baselineRegisterOffset ? GPRInfo::regT0 : reg.gpr();

            if (unwindIndex == UINT_MAX) {
                // The FTL compilation didn't preserve this register. This means that it also
                // didn't use the register. So its value at the beginning of OSR exit should be
                // preserved by the thunk. Luckily, we saved all registers into the register
                // scratch buffer, so we can restore them from there.
                jit.load64(registerScratch + offsetOfReg(reg), regToLoad);