void
MBasicBlock::removePredecessor(MBasicBlock *pred)
{
JS_ASSERT(numPredecessors() >= 2);
for (size_t i = 0; i < numPredecessors(); i++) {
if (getPredecessor(i) != pred)
continue;
// Adjust phis. Note that this can leave redundant phis
// behind.
if (!phisEmpty()) {
JS_ASSERT(pred->successorWithPhis());
JS_ASSERT(pred->positionInPhiSuccessor() == i);
for (MPhiIterator iter = phisBegin(); iter != phisEnd(); iter++)
iter->removeOperand(i);
for (size_t j = i+1; j < numPredecessors(); j++)
getPredecessor(j)->setSuccessorWithPhis(this, j - 1);
}
// Remove from pred list.
MBasicBlock **ptr = predecessors_.begin() + i;
predecessors_.erase(ptr);
return;
}
JS_NOT_REACHED("predecessor was not found");
}
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;
}
void
MBasicBlock::removePredecessor(MBasicBlock *pred)
{
// If we're removing the last backedge, this is no longer a loop.
if (isLoopHeader() && hasUniqueBackedge() && backedge() == pred)
clearLoopHeader();
for (size_t i = 0; i < numPredecessors(); i++) {
if (getPredecessor(i) != pred)
continue;
// Adjust phis. Note that this can leave redundant phis
// behind.
if (!phisEmpty()) {
JS_ASSERT(pred->successorWithPhis());
JS_ASSERT(pred->positionInPhiSuccessor() == i);
for (MPhiIterator iter = phisBegin(); iter != phisEnd(); iter++)
iter->removeOperand(i);
pred->setSuccessorWithPhis(nullptr, 0);
for (size_t j = i+1; j < numPredecessors(); j++)
getPredecessor(j)->setSuccessorWithPhis(this, j - 1);
}
// Remove from pred list.
MBasicBlock **ptr = predecessors_.begin() + i;
predecessors_.erase(ptr);
return;
}
MOZ_ASSUME_UNREACHABLE("predecessor was not found");
}
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;
}
