void
EffectiveAddressAnalysis::analyzeAsmHeapAccess(MAsmJSHeapAccessType* ins)
{
MDefinition* ptr = ins->ptr();
if (ptr->isConstantValue()) {
// Look for heap[i] where i is a constant offset, and fold the offset.
// By doing the folding now, we simplify the task of codegen; the offset
// is always the address mode immediate. This also allows it to avoid
// a situation where the sum of a constant pointer value and a non-zero
// offset doesn't actually fit into the address mode immediate.
int32_t imm = ptr->constantValue().toInt32();
if (imm != 0 && tryAddDisplacement(ins, imm)) {
MInstruction* zero = MConstant::New(graph_.alloc(), Int32Value(0));
ins->block()->insertBefore(ins, zero);
ins->replacePtr(zero);
}
} else if (ptr->isAdd()) {
// Look for heap[a+i] where i is a constant offset, and fold the offset.
// Alignment masks have already been moved out of the way by the
// Alignment Mask Analysis pass.
MDefinition* op0 = ptr->toAdd()->getOperand(0);
MDefinition* op1 = ptr->toAdd()->getOperand(1);
if (op0->isConstantValue())
mozilla::Swap(op0, op1);
if (op1->isConstantValue()) {
int32_t imm = op1->constantValue().toInt32();
if (tryAddDisplacement(ins, imm))
ins->replacePtr(op0);
}
}
}
void
LIRGeneratorMIPS::visitAsmJSStoreHeap(MAsmJSStoreHeap *ins)
{
MDefinition *ptr = ins->ptr();
MOZ_ASSERT(ptr->type() == MIRType_Int32);
LAllocation ptrAlloc;
if (ptr->isConstantValue() && !ins->needsBoundsCheck()) {
MOZ_ASSERT(ptr->constantValue().toInt32() >= 0);
ptrAlloc = LAllocation(ptr->constantVp());
} else
ptrAlloc = useRegisterAtStart(ptr);
add(new(alloc()) LAsmJSStoreHeap(ptrAlloc, useRegisterAtStart(ins->value())), ins);
}
void
LIRGeneratorMIPS::visitAsmJSLoadHeap(MAsmJSLoadHeap *ins)
{
MDefinition *ptr = ins->ptr();
MOZ_ASSERT(ptr->type() == MIRType_Int32);
LAllocation ptrAlloc;
// For MIPS it is best to keep the 'ptr' in a register if a bounds check
// is needed.
if (ptr->isConstantValue() && !ins->needsBoundsCheck()) {
// A bounds check is only skipped for a positive index.
MOZ_ASSERT(ptr->constantValue().toInt32() >= 0);
ptrAlloc = LAllocation(ptr->constantVp());
} else
ptrAlloc = useRegisterAtStart(ptr);
define(new(alloc()) LAsmJSLoadHeap(ptrAlloc), ins);
}
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);
MDefinition* shift = lsh->rhs();
if (!shift->isConstantValue())
return;
Value shiftValue = shift->constantValue();
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 - add->indexOf(*use));
if (other->isConstantValue()) {
displacement += other->constantValue().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));
if (!other->isConstantValue() || !other->constantValue().isInt32())
return;
uint32_t bitsClearedByShift = elemSize - 1;
uint32_t bitsClearedByMask = ~uint32_t(other->constantValue().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);
}
