C++ CCallHelpers::branch32方法代码示例

void handleExitCounts(CCallHelpers& jit, const OSRExitBase& exit)
{
    jit.add32(AssemblyHelpers::TrustedImm32(1), AssemblyHelpers::AbsoluteAddress(&exit.m_count));
    
    jit.move(AssemblyHelpers::TrustedImmPtr(jit.codeBlock()), GPRInfo::regT0);
    
    AssemblyHelpers::Jump tooFewFails;
    
    jit.load32(AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfOSRExitCounter()), GPRInfo::regT2);
    jit.add32(AssemblyHelpers::TrustedImm32(1), GPRInfo::regT2);
    jit.store32(GPRInfo::regT2, AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfOSRExitCounter()));
    
    jit.move(AssemblyHelpers::TrustedImmPtr(jit.baselineCodeBlock()), GPRInfo::regT0);
    AssemblyHelpers::Jump reoptimizeNow = jit.branch32(
        AssemblyHelpers::GreaterThanOrEqual,
        AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecuteCounter()),
        AssemblyHelpers::TrustedImm32(0));
        
    tooFewFails = jit.branch32(AssemblyHelpers::BelowOrEqual, GPRInfo::regT2, AssemblyHelpers::TrustedImm32(jit.codeBlock()->exitCountThresholdForReoptimization()));
    
    reoptimizeNow.link(&jit);
    
    // Reoptimize as soon as possible.
#if !NUMBER_OF_ARGUMENT_REGISTERS
    jit.poke(GPRInfo::regT0);
#else
    jit.move(GPRInfo::regT0, GPRInfo::argumentGPR0);
    ASSERT(GPRInfo::argumentGPR0 != GPRInfo::regT1);
#endif
    jit.move(AssemblyHelpers::TrustedImmPtr(bitwise_cast<void*>(triggerReoptimizationNow)), GPRInfo::regT1);
    jit.call(GPRInfo::regT1);
    AssemblyHelpers::Jump doneAdjusting = jit.jump();
    
    tooFewFails.link(&jit);
    
    // Adjust the execution counter such that the target is to only optimize after a while.
    int32_t activeThreshold =
        jit.baselineCodeBlock()->adjustedCounterValue(
            Options::thresholdForOptimizeAfterLongWarmUp());
    int32_t targetValue = ExecutionCounter::applyMemoryUsageHeuristicsAndConvertToInt(
        activeThreshold, jit.baselineCodeBlock());
    int32_t clippedValue =
        ExecutionCounter::clippedThreshold(jit.codeBlock()->globalObject(), targetValue);
    jit.store32(AssemblyHelpers::TrustedImm32(-clippedValue), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecuteCounter()));
    jit.store32(AssemblyHelpers::TrustedImm32(activeThreshold), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecutionActiveThreshold()));
    jit.store32(AssemblyHelpers::TrustedImm32(ExecutionCounter::formattedTotalCount(clippedValue)), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecutionTotalCount()));
    
    doneAdjusting.link(&jit);
}

void emitSetupVarargsFrameFastCase(CCallHelpers& jit, GPRReg numUsedSlotsGPR, GPRReg scratchGPR1, GPRReg scratchGPR2, GPRReg scratchGPR3, ValueRecovery argCountRecovery, VirtualRegister firstArgumentReg, unsigned firstVarArgOffset, CCallHelpers::JumpList& slowCase)
{
    CCallHelpers::JumpList end;
    
    if (argCountRecovery.isConstant()) {
        // FIXME: We could constant-fold a lot of the computation below in this case.
        // https://bugs.webkit.org/show_bug.cgi?id=141486
        jit.move(CCallHelpers::TrustedImm32(argCountRecovery.constant().asInt32()), scratchGPR1);
    } else
        jit.load32(CCallHelpers::payloadFor(argCountRecovery.virtualRegister()), scratchGPR1);
    if (firstVarArgOffset) {
        CCallHelpers::Jump sufficientArguments = jit.branch32(CCallHelpers::GreaterThan, scratchGPR1, CCallHelpers::TrustedImm32(firstVarArgOffset + 1));
        jit.move(CCallHelpers::TrustedImm32(1), scratchGPR1);
        CCallHelpers::Jump endVarArgs = jit.jump();
        sufficientArguments.link(&jit);
        jit.sub32(CCallHelpers::TrustedImm32(firstVarArgOffset), scratchGPR1);
        endVarArgs.link(&jit);
    }
    slowCase.append(jit.branch32(CCallHelpers::Above, scratchGPR1, CCallHelpers::TrustedImm32(maxArguments + 1)));
    
    emitSetVarargsFrame(jit, scratchGPR1, true, numUsedSlotsGPR, scratchGPR2);

    slowCase.append(jit.branchPtr(CCallHelpers::Above, CCallHelpers::AbsoluteAddress(jit.vm()->addressOfStackLimit()), scratchGPR2));

    // Initialize ArgumentCount.
    jit.store32(scratchGPR1, CCallHelpers::Address(scratchGPR2, JSStack::ArgumentCount * static_cast<int>(sizeof(Register)) + PayloadOffset));

    // Copy arguments.
    jit.signExtend32ToPtr(scratchGPR1, scratchGPR1);
    CCallHelpers::Jump done = jit.branchSubPtr(CCallHelpers::Zero, CCallHelpers::TrustedImm32(1), scratchGPR1);
    // scratchGPR1: argumentCount

    CCallHelpers::Label copyLoop = jit.label();
    int argOffset = (firstArgumentReg.offset() - 1 + firstVarArgOffset) * static_cast<int>(sizeof(Register));
#if USE(JSVALUE64)
    jit.load64(CCallHelpers::BaseIndex(GPRInfo::callFrameRegister, scratchGPR1, CCallHelpers::TimesEight, argOffset), scratchGPR3);
    jit.store64(scratchGPR3, CCallHelpers::BaseIndex(scratchGPR2, scratchGPR1, CCallHelpers::TimesEight, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register))));
#else // USE(JSVALUE64), so this begins the 32-bit case
    jit.load32(CCallHelpers::BaseIndex(GPRInfo::callFrameRegister, scratchGPR1, CCallHelpers::TimesEight, argOffset + TagOffset), scratchGPR3);
    jit.store32(scratchGPR3, CCallHelpers::BaseIndex(scratchGPR2, scratchGPR1, CCallHelpers::TimesEight, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)) + TagOffset));
    jit.load32(CCallHelpers::BaseIndex(GPRInfo::callFrameRegister, scratchGPR1, CCallHelpers::TimesEight, argOffset + PayloadOffset), scratchGPR3);
    jit.store32(scratchGPR3, CCallHelpers::BaseIndex(scratchGPR2, scratchGPR1, CCallHelpers::TimesEight, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)) + PayloadOffset));
#endif // USE(JSVALUE64), end of 32-bit case
    jit.branchSubPtr(CCallHelpers::NonZero, CCallHelpers::TrustedImm32(1), scratchGPR1).linkTo(copyLoop, &jit);
    
    done.link(&jit);
}

void handleExitCounts(CCallHelpers& jit, const OSRExitBase& exit)
{
    jit.add32(AssemblyHelpers::TrustedImm32(1), AssemblyHelpers::AbsoluteAddress(&exit.m_count));

    jit.move(AssemblyHelpers::TrustedImmPtr(jit.codeBlock()), GPRInfo::regT0);

    AssemblyHelpers::Jump tooFewFails;

    jit.load32(AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfOSRExitCounter()), GPRInfo::regT2);
    jit.add32(AssemblyHelpers::TrustedImm32(1), GPRInfo::regT2);
    jit.store32(GPRInfo::regT2, AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfOSRExitCounter()));

    jit.move(AssemblyHelpers::TrustedImmPtr(jit.baselineCodeBlock()), GPRInfo::regT0);
    AssemblyHelpers::Jump reoptimizeNow = jit.branch32(
        AssemblyHelpers::GreaterThanOrEqual,
        AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecuteCounter()),
        AssemblyHelpers::TrustedImm32(0));

    // We want to figure out if there's a possibility that we're in a loop. For the outermost
    // code block in the inline stack, we handle this appropriately by having the loop OSR trigger
    // check the exit count of the replacement of the CodeBlock from which we are OSRing. The
    // problem is the inlined functions, which might also have loops, but whose baseline versions
    // don't know where to look for the exit count. Figure out if those loops are severe enough
    // that we had tried to OSR enter. If so, then we should use the loop reoptimization trigger.
    // Otherwise, we should use the normal reoptimization trigger.

    AssemblyHelpers::JumpList loopThreshold;

    for (InlineCallFrame* inlineCallFrame = exit.m_codeOrigin.inlineCallFrame; inlineCallFrame; inlineCallFrame = inlineCallFrame->caller.inlineCallFrame) {
        loopThreshold.append(
            jit.branchTest8(
                AssemblyHelpers::NonZero,
                AssemblyHelpers::AbsoluteAddress(
                    inlineCallFrame->executable->addressOfDidTryToEnterInLoop())));
    }

    jit.move(
        AssemblyHelpers::TrustedImm32(jit.codeBlock()->exitCountThresholdForReoptimization()),
        GPRInfo::regT1);

    if (!loopThreshold.empty()) {
        AssemblyHelpers::Jump done = jit.jump();

        loopThreshold.link(&jit);
        jit.move(
            AssemblyHelpers::TrustedImm32(
                jit.codeBlock()->exitCountThresholdForReoptimizationFromLoop()),
            GPRInfo::regT1);

        done.link(&jit);
    }

    tooFewFails = jit.branch32(AssemblyHelpers::BelowOrEqual, GPRInfo::regT2, GPRInfo::regT1);

    reoptimizeNow.link(&jit);

    // Reoptimize as soon as possible.
#if !NUMBER_OF_ARGUMENT_REGISTERS
    jit.poke(GPRInfo::regT0);
    jit.poke(AssemblyHelpers::TrustedImmPtr(&exit), 1);
#else
    jit.move(GPRInfo::regT0, GPRInfo::argumentGPR0);
    jit.move(AssemblyHelpers::TrustedImmPtr(&exit), GPRInfo::argumentGPR1);
#endif
    jit.move(AssemblyHelpers::TrustedImmPtr(bitwise_cast<void*>(triggerReoptimizationNow)), GPRInfo::nonArgGPR0);
    jit.call(GPRInfo::nonArgGPR0);
    AssemblyHelpers::Jump doneAdjusting = jit.jump();

    tooFewFails.link(&jit);

    // Adjust the execution counter such that the target is to only optimize after a while.
    int32_t activeThreshold =
        jit.baselineCodeBlock()->adjustedCounterValue(
            Options::thresholdForOptimizeAfterLongWarmUp());
    int32_t targetValue = applyMemoryUsageHeuristicsAndConvertToInt(
        activeThreshold, jit.baselineCodeBlock());
    int32_t clippedValue;
    switch (jit.codeBlock()->jitType()) {
    case JITCode::DFGJIT:
        clippedValue = BaselineExecutionCounter::clippedThreshold(jit.codeBlock()->globalObject(), targetValue);
        break;
    case JITCode::FTLJIT:
        clippedValue = UpperTierExecutionCounter::clippedThreshold(jit.codeBlock()->globalObject(), targetValue);
        break;
    default:
        RELEASE_ASSERT_NOT_REACHED();
#if COMPILER_QUIRK(CONSIDERS_UNREACHABLE_CODE)
        clippedValue = 0; // Make some compilers, and mhahnenberg, happy.
#endif
        break;
    }
    jit.store32(AssemblyHelpers::TrustedImm32(-clippedValue), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecuteCounter()));
    jit.store32(AssemblyHelpers::TrustedImm32(activeThreshold), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecutionActiveThreshold()));
    jit.store32(AssemblyHelpers::TrustedImm32(formattedTotalExecutionCount(clippedValue)), AssemblyHelpers::Address(GPRInfo::regT0, CodeBlock::offsetOfJITExecutionTotalCount()));

    doneAdjusting.link(&jit);
}