C++ (Cpp) MInstruction::replaceAllUsesWith Examples

Example #1

File: EffectiveAddressAnalysis.cpp Project: Wafflespeanut/gecko-dev

static void
AnalyzeLsh(TempAllocator& alloc, MLsh* lsh)
{
    if (lsh->specialization() != MIRType::Int32)
        return;

    if (lsh->isRecoveredOnBailout())
        return;

    MDefinition* index = lsh->lhs();
    MOZ_ASSERT(index->type() == MIRType::Int32);

    MConstant* shiftValue = lsh->rhs()->maybeConstantValue();
    if (!shiftValue)
        return;

    if (shiftValue->type() != MIRType::Int32 || !IsShiftInScaleRange(shiftValue->toInt32()))
        return;

    Scale scale = ShiftToScale(shiftValue->toInt32());

    int32_t displacement = 0;
    MInstruction* last = lsh;
    MDefinition* base = nullptr;
    while (true) {
        if (!last->hasOneUse())
            break;

        MUseIterator use = last->usesBegin();
        if (!use->consumer()->isDefinition() || !use->consumer()->toDefinition()->isAdd())
            break;

        MAdd* add = use->consumer()->toDefinition()->toAdd();
        if (add->specialization() != MIRType::Int32 || !add->isTruncated())
            break;

        MDefinition* other = add->getOperand(1 - add->indexOf(*use));

        if (MConstant* otherConst = other->maybeConstantValue()) {
            displacement += otherConst->toInt32();
        } else {
            if (base)
                break;
            base = other;
        }

        last = add;
        if (last->isRecoveredOnBailout())
            return;
    }

    if (!base) {
        uint32_t elemSize = 1 << ScaleToShift(scale);
        if (displacement % elemSize != 0)
            return;

        if (!last->hasOneUse())
            return;

        MUseIterator use = last->usesBegin();
        if (!use->consumer()->isDefinition() || !use->consumer()->toDefinition()->isBitAnd())
            return;

        MBitAnd* bitAnd = use->consumer()->toDefinition()->toBitAnd();
        if (bitAnd->isRecoveredOnBailout())
            return;

        MDefinition* other = bitAnd->getOperand(1 - bitAnd->indexOf(*use));
        MConstant* otherConst = other->maybeConstantValue();
        if (!otherConst || otherConst->type() != MIRType::Int32)
            return;

        uint32_t bitsClearedByShift = elemSize - 1;
        uint32_t bitsClearedByMask = ~uint32_t(otherConst->toInt32());
        if ((bitsClearedByShift & bitsClearedByMask) != bitsClearedByMask)
            return;

        bitAnd->replaceAllUsesWith(last);
        return;
    }

    if (base->isRecoveredOnBailout())
        return;

    MEffectiveAddress* eaddr = MEffectiveAddress::New(alloc, base, index, scale, displacement);
    last->replaceAllUsesWith(eaddr);
    last->block()->insertAfter(last, eaddr);
}

Example #2

File: EffectiveAddressAnalysis.cpp Project: armikhael/cunaguaro

static void
AnalyzeLsh(MBasicBlock *block, MLsh *lsh)
{
    if (lsh->specialization() != MIRType_Int32)
        return;

    MDefinition *index = lsh->lhs();
    JS_ASSERT(index->type() == MIRType_Int32);

    MDefinition *shift = lsh->rhs();
    if (!shift->isConstant())
        return;

    Value shiftValue = shift->toConstant()->value();
    if (!shiftValue.isInt32() || !IsShiftInScaleRange(shiftValue.toInt32()))
        return;

    Scale scale = ShiftToScale(shiftValue.toInt32());

    int32_t displacement = 0;
    MInstruction *last = lsh;
    MDefinition *base = nullptr;
    while (true) {
        if (!last->hasOneUse())
            break;

        MUseIterator use = last->usesBegin();
        if (!use->consumer()->isDefinition() || !use->consumer()->toDefinition()->isAdd())
            break;

        MAdd *add = use->consumer()->toDefinition()->toAdd();
        if (add->specialization() != MIRType_Int32 || !add->isTruncated())
            break;

        MDefinition *other = add->getOperand(1 - use->index());

        if (other->isConstant()) {
            displacement += other->toConstant()->value().toInt32();
        } else {
            if (base)
                break;
            base = other;
        }

        last = add;
    }

    if (!base) {
        uint32_t elemSize = 1 << ScaleToShift(scale);
        if (displacement % elemSize != 0)
            return;

        if (!last->hasOneUse())
            return;

        MUseIterator use = last->usesBegin();
        if (!use->consumer()->isDefinition() || !use->consumer()->toDefinition()->isBitAnd())
            return;

        MBitAnd *bitAnd = use->consumer()->toDefinition()->toBitAnd();
        MDefinition *other = bitAnd->getOperand(1 - use->index());
        if (!other->isConstant() || !other->toConstant()->value().isInt32())
            return;

        uint32_t bitsClearedByShift = elemSize - 1;
        uint32_t bitsClearedByMask = ~uint32_t(other->toConstant()->value().toInt32());
        if ((bitsClearedByShift & bitsClearedByMask) != bitsClearedByMask)
            return;

        bitAnd->replaceAllUsesWith(last);
        return;
    }

    MEffectiveAddress *eaddr = MEffectiveAddress::New(base, index, scale, displacement);
    last->replaceAllUsesWith(eaddr);
    block->insertAfter(last, eaddr);
}