// Transform:
//
// [AddI]
// addl $9, %esi
// [LoadUnboxedScalar]
// movsd 0x0(%rbx,%rsi,8), %xmm4
//
// into:
//
// [LoadUnboxedScalar]
// movsd 0x48(%rbx,%rsi,8), %xmm4
//
// This is possible when the AddI is only used by the LoadUnboxedScalar opcode.
static void
AnalyzeLoadUnboxedScalar(TempAllocator& alloc, MLoadUnboxedScalar* load)
{
if (load->isRecoveredOnBailout())
return;
if (!load->getOperand(1)->isAdd())
return;
JitSpew(JitSpew_EAA, "analyze: %s%u", load->opName(), load->id());
MAdd* add = load->getOperand(1)->toAdd();
if (add->specialization() != MIRType::Int32 || !add->hasUses() ||
add->truncateKind() != MDefinition::TruncateKind::Truncate)
{
return;
}
MDefinition* lhs = add->lhs();
MDefinition* rhs = add->rhs();
MDefinition* constant = nullptr;
MDefinition* node = nullptr;
if (lhs->isConstant()) {
constant = lhs;
node = rhs;
} else if (rhs->isConstant()) {
constant = rhs;
node = lhs;
} else
return;
MOZ_ASSERT(constant->type() == MIRType::Int32);
size_t storageSize = Scalar::byteSize(load->storageType());
int32_t c1 = load->offsetAdjustment();
int32_t c2 = 0;
if (!SafeMul(constant->maybeConstantValue()->toInt32(), storageSize, &c2))
return;
int32_t offset = 0;
if (!SafeAdd(c1, c2, &offset))
return;
JitSpew(JitSpew_EAA, "set offset: %d + %d = %d on: %s%u", c1, c2, offset,
load->opName(), load->id());
load->setOffsetAdjustment(offset);
load->replaceOperand(1, node);
if (!add->hasLiveDefUses() && DeadIfUnused(add) && add->canRecoverOnBailout()) {
JitSpew(JitSpew_EAA, "mark as recovered on bailout: %s%u",
add->opName(), add->id());
add->setRecoveredOnBailoutUnchecked();
}
}
// Fold AddIs with one variable and two or more constants into one AddI.
static void AnalyzeAdd(TempAllocator& alloc, MAdd* add) {
if (add->specialization() != MIRType::Int32 || add->isRecoveredOnBailout()) {
return;
}
if (!add->hasUses()) {
return;
}
JitSpew(JitSpew_FLAC, "analyze add: %s%u", add->opName(), add->id());
SimpleLinearSum sum = ExtractLinearSum(add);
if (sum.constant == 0 || !sum.term) {
return;
}
// Determine which operand is the constant.
int idx = add->getOperand(0)->isConstant() ? 0 : 1;
if (add->getOperand(idx)->isConstant()) {
// Do not replace an add where the outcome is the same add instruction.
MOZ_ASSERT(add->getOperand(idx)->toConstant()->type() == MIRType::Int32);
if (sum.term == add->getOperand(1 - idx) ||
sum.constant == add->getOperand(idx)->toConstant()->toInt32()) {
return;
}
}
MInstruction* rhs = MConstant::New(alloc, Int32Value(sum.constant));
add->block()->insertBefore(add, rhs);
MAdd* addNew =
MAdd::New(alloc, sum.term, rhs, MIRType::Int32, add->truncateKind());
add->replaceAllLiveUsesWith(addNew);
add->block()->insertBefore(add, addNew);
JitSpew(JitSpew_FLAC, "replaced with: %s%u", addNew->opName(), addNew->id());
JitSpew(JitSpew_FLAC, "and constant: %s%u (%d)", rhs->opName(), rhs->id(),
sum.constant);
// Mark the stale nodes as RecoveredOnBailout since the Sink pass has
// been run before this pass. DCE will then remove the unused nodes.
markNodesAsRecoveredOnBailout(add);
}
