/// removePred - This removes the specified edge as a pred of the current
/// node if it exists. It also removes the current node as a successor of
/// the specified node.
void SUnit::removePred(const SDep &D) {
// Find the matching predecessor.
for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end();
I != E; ++I)
if (*I == D) {
// Find the corresponding successor in N.
SDep P = D;
P.setSUnit(this);
SUnit *N = D.getSUnit();
SmallVectorImpl<SDep>::iterator Succ = std::find(N->Succs.begin(),
N->Succs.end(), P);
assert(Succ != N->Succs.end() && "Mismatching preds / succs lists!");
N->Succs.erase(Succ);
Preds.erase(I);
// Update the bookkeeping.
if (P.getKind() == SDep::Data) {
assert(NumPreds > 0 && "NumPreds will underflow!");
assert(N->NumSuccs > 0 && "NumSuccs will underflow!");
--NumPreds;
--N->NumSuccs;
}
if (!N->isScheduled) {
if (D.isWeak())
--WeakPredsLeft;
else {
assert(NumPredsLeft > 0 && "NumPredsLeft will underflow!");
--NumPredsLeft;
}
}
if (!isScheduled) {
if (D.isWeak())
--N->WeakSuccsLeft;
else {
assert(N->NumSuccsLeft > 0 && "NumSuccsLeft will underflow!");
--N->NumSuccsLeft;
}
}
if (P.getLatency() != 0) {
this->setDepthDirty();
N->setHeightDirty();
}
return;
}
}
/// releaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
/// the PendingQueue if the count reaches zero. Also update its cycle bound.
void ScheduleDAGVLIW::releaseSucc(SUnit *SU, const SDep &D) {
SUnit *SuccSU = D.getSUnit();
#ifndef NDEBUG
if (SuccSU->NumPredsLeft == 0) {
dbgs() << "*** Scheduling failed! ***\n";
SuccSU->dump(this);
dbgs() << " has been released too many times!\n";
llvm_unreachable(nullptr);
}
#endif
assert(!D.isWeak() && "unexpected artificial DAG edge");
--SuccSU->NumPredsLeft;
SuccSU->setDepthToAtLeast(SU->getDepth() + D.getLatency());
// If all the node's predecessors are scheduled, this node is ready
// to be scheduled. Ignore the special ExitSU node.
if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU) {
PendingQueue.push_back(SuccSU);
}
}
/// addPred - This adds the specified edge as a pred of the current node if
/// not already. It also adds the current node as a successor of the
/// specified node.
bool SUnit::addPred(const SDep &D, bool Required) {
// If this node already has this dependence, don't add a redundant one.
for (SmallVectorImpl<SDep>::iterator I = Preds.begin(), E = Preds.end();
I != E; ++I) {
// Zero-latency weak edges may be added purely for heuristic ordering. Don't
// add them if another kind of edge already exists.
if (!Required && I->getSUnit() == D.getSUnit())
return false;
if (I->overlaps(D)) {
// Extend the latency if needed. Equivalent to removePred(I) + addPred(D).
if (I->getLatency() < D.getLatency()) {
SUnit *PredSU = I->getSUnit();
// Find the corresponding successor in N.
SDep ForwardD = *I;
ForwardD.setSUnit(this);
for (SmallVectorImpl<SDep>::iterator II = PredSU->Succs.begin(),
EE = PredSU->Succs.end(); II != EE; ++II) {
if (*II == ForwardD) {
II->setLatency(D.getLatency());
break;
}
}
I->setLatency(D.getLatency());
}
return false;
}
}
// Now add a corresponding succ to N.
SDep P = D;
P.setSUnit(this);
SUnit *N = D.getSUnit();
// Update the bookkeeping.
if (D.getKind() == SDep::Data) {
assert(NumPreds < UINT_MAX && "NumPreds will overflow!");
assert(N->NumSuccs < UINT_MAX && "NumSuccs will overflow!");
++NumPreds;
++N->NumSuccs;
}
if (!N->isScheduled) {
if (D.isWeak()) {
++WeakPredsLeft;
}
else {
assert(NumPredsLeft < UINT_MAX && "NumPredsLeft will overflow!");
++NumPredsLeft;
}
}
if (!isScheduled) {
if (D.isWeak()) {
++N->WeakSuccsLeft;
}
else {
assert(N->NumSuccsLeft < UINT_MAX && "NumSuccsLeft will overflow!");
++N->NumSuccsLeft;
}
}
Preds.push_back(D);
N->Succs.push_back(P);
if (P.getLatency() != 0) {
this->setDepthDirty();
N->setHeightDirty();
}
return true;
}
