AbortReason
MBasicBlock::setBackedge(MBasicBlock *pred)
{
// Predecessors must be finished, and at the correct stack depth.
JS_ASSERT(lastIns_);
JS_ASSERT(pred->lastIns_);
JS_ASSERT(pred->stackDepth() == entryResumePoint()->stackDepth());
// We must be a pending loop header
JS_ASSERT(kind_ == PENDING_LOOP_HEADER);
bool hadTypeChange = false;
// Add exit definitions to each corresponding phi at the entry.
if (!inheritPhisFromBackedge(pred, &hadTypeChange))
return AbortReason_Alloc;
if (hadTypeChange) {
for (MPhiIterator phi = phisBegin(); phi != phisEnd(); phi++)
phi->removeOperand(phi->numOperands() - 1);
return AbortReason_Disable;
}
// We are now a loop header proper
kind_ = LOOP_HEADER;
if (!predecessors_.append(pred))
return AbortReason_Alloc;
return AbortReason_NoAbort;
}
AbortReason
MBasicBlock::setBackedge(MBasicBlock *pred)
{
// Predecessors must be finished, and at the correct stack depth.
JS_ASSERT(lastIns_);
JS_ASSERT(pred->lastIns_);
JS_ASSERT(pred->stackDepth() == entryResumePoint()->stackDepth());
// We must be a pending loop header
JS_ASSERT(kind_ == PENDING_LOOP_HEADER);
bool hadTypeChange = false;
// Add exit definitions to each corresponding phi at the entry.
for (MPhiIterator phi = phisBegin(); phi != phisEnd(); phi++) {
MPhi *entryDef = *phi;
MDefinition *exitDef = pred->slots_[entryDef->slot()];
// Assert that we already placed phis for each slot.
JS_ASSERT(entryDef->block() == this);
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);
}
bool typeChange = false;
if (!entryDef->addInputSlow(exitDef, &typeChange))
return AbortReason_Alloc;
hadTypeChange |= typeChange;
JS_ASSERT(entryDef->slot() < pred->stackDepth());
setSlot(entryDef->slot(), entryDef);
}
if (hadTypeChange) {
for (MPhiIterator phi = phisBegin(); phi != phisEnd(); phi++)
phi->removeOperand(phi->numOperands() - 1);
return AbortReason_Disable;
}
// We are now a loop header proper
kind_ = LOOP_HEADER;
if (!predecessors_.append(pred))
return AbortReason_Alloc;
return AbortReason_NoAbort;
}
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);
}
MPhiIterator
MBasicBlock::discardPhiAt(MPhiIterator &at)
{
JS_ASSERT(!phis_.empty());
for (size_t i = 0; i < at->numOperands(); i++)
at->discardOperand(i);
MPhiIterator result = phis_.removeAt(at);
if (phis_.empty()) {
for (MBasicBlock **pred = predecessors_.begin(); pred != predecessors_.end(); pred++)
(*pred)->setSuccessorWithPhis(NULL, 0);
}
return result;
}
