MBasicBlock*
MBasicBlock::New(MIRGraph& graph, const CompileInfo& info, MBasicBlock* pred, Kind kind)
{
BytecodeSite* site = new(graph.alloc()) BytecodeSite();
MBasicBlock* block = new(graph.alloc()) MBasicBlock(graph, info, site, kind);
if (!block->init())
return nullptr;
if (pred) {
block->stackPosition_ = pred->stackPosition_;
if (block->kind_ == PENDING_LOOP_HEADER) {
size_t nphis = block->stackPosition_;
size_t nfree = graph.phiFreeListLength();
TempAllocator& alloc = graph.alloc();
MPhi* phis = nullptr;
if (nphis > nfree) {
phis = alloc.allocateArray<MPhi>(nphis - nfree);
if (!phis)
return nullptr;
}
// Note: Phis are inserted in the same order as the slots.
for (size_t i = 0; i < nphis; i++) {
MDefinition* predSlot = pred->getSlot(i);
MOZ_ASSERT(predSlot->type() != MIRType::Value);
MPhi* phi;
if (i < nfree)
phi = graph.takePhiFromFreeList();
else
phi = phis + (i - nfree);
new(phi) MPhi(alloc, predSlot->type());
phi->addInlineInput(predSlot);
// Add append Phis in the block.
block->addPhi(phi);
block->setSlot(i, phi);
}
} else {
block->copySlots(pred);
}
if (!block->predecessors_.append(pred))
return nullptr;
}
return block;
}
bool
MBasicBlock::setBackedgeWasm(MBasicBlock* pred)
{
// Predecessors must be finished, and at the correct stack depth.
MOZ_ASSERT(hasLastIns());
MOZ_ASSERT(pred->hasLastIns());
MOZ_ASSERT(stackDepth() == pred->stackDepth());
// We must be a pending loop header
MOZ_ASSERT(kind_ == PENDING_LOOP_HEADER);
// Add exit definitions to each corresponding phi at the entry.
// Note: Phis are inserted in the same order as the slots. (see
// MBasicBlock::New)
size_t slot = 0;
for (MPhiIterator phi = phisBegin(); phi != phisEnd(); phi++, slot++) {
MPhi* entryDef = *phi;
MDefinition* exitDef = pred->getSlot(slot);
// Assert that we already placed phis for each slot.
MOZ_ASSERT(entryDef->block() == this);
// Assert that the phi already has the correct type.
MOZ_ASSERT(entryDef->type() == exitDef->type());
MOZ_ASSERT(entryDef->type() != MIRType::Value);
if (entryDef == exitDef) {
// If the exit def is the same as the entry def, make a redundant
// phi. Since loop headers have exactly two incoming edges, we
// know that that's just the first input.
//
// Note that we eliminate later rather than now, to avoid any
// weirdness around pending continue edges which might still hold
// onto phis.
exitDef = entryDef->getOperand(0);
}
// Phis always have room for 2 operands, so this can't fail.
MOZ_ASSERT(phi->numOperands() == 1);
entryDef->addInlineInput(exitDef);
MOZ_ASSERT(slot < pred->stackDepth());
setSlot(slot, entryDef);
}
// We are now a loop header proper
kind_ = LOOP_HEADER;
return predecessors_.append(pred);
}
bool
MBasicBlock::inherit(TempAllocator& alloc, size_t stackDepth, MBasicBlock* maybePred,
uint32_t popped, unsigned stackPhiCount)
{
MOZ_ASSERT_IF(maybePred, maybePred->stackDepth() == stackDepth);
MOZ_ASSERT(stackDepth >= popped);
stackDepth -= popped;
stackPosition_ = stackDepth;
if (maybePred && kind_ != PENDING_LOOP_HEADER)
copySlots(maybePred);
MOZ_ASSERT(info_.nslots() >= stackPosition_);
MOZ_ASSERT(!entryResumePoint_);
// Propagate the caller resume point from the inherited block.
callerResumePoint_ = maybePred ? maybePred->callerResumePoint() : nullptr;
// Create a resume point using our initial stack state.
entryResumePoint_ = new(alloc) MResumePoint(this, pc(), MResumePoint::ResumeAt);
if (!entryResumePoint_->init(alloc))
return false;
if (maybePred) {
if (!predecessors_.append(maybePred))
return false;
if (kind_ == PENDING_LOOP_HEADER) {
size_t i = 0;
for (i = 0; i < info().firstStackSlot(); i++) {
MPhi* phi = MPhi::New(alloc.fallible());
if (!phi)
return false;
phi->addInlineInput(maybePred->getSlot(i));
addPhi(phi);
setSlot(i, phi);
entryResumePoint()->initOperand(i, phi);
}
MOZ_ASSERT(stackPhiCount <= stackDepth);
MOZ_ASSERT(info().firstStackSlot() <= stackDepth - stackPhiCount);
// Avoid creating new phis for stack values that aren't part of the
// loop. Note that for loop headers that can OSR, all values on the
// stack are part of the loop.
for (; i < stackDepth - stackPhiCount; i++) {
MDefinition* val = maybePred->getSlot(i);
setSlot(i, val);
entryResumePoint()->initOperand(i, val);
}
for (; i < stackDepth; i++) {
MPhi* phi = MPhi::New(alloc.fallible());
if (!phi)
return false;
phi->addInlineInput(maybePred->getSlot(i));
addPhi(phi);
setSlot(i, phi);
entryResumePoint()->initOperand(i, phi);
}
} else {
for (size_t i = 0; i < stackDepth; i++)
entryResumePoint()->initOperand(i, getSlot(i));
}
} else {
/*
* Don't leave the operands uninitialized for the caller, as it may not
* initialize them later on.
*/
for (size_t i = 0; i < stackDepth; i++)
entryResumePoint()->clearOperand(i);
}
return true;
}