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sched: Avoid trivially redundant DAG edges. Take the one with higher latency.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158379 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2012-06-13 02:39:00 +00:00
parent a256ac5210
commit 9df55eed04
2 changed files with 27 additions and 5 deletions
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9
include/llvm/CodeGen/ScheduleDAG.h
View File

@ -117,8 +117,9 @@ namespace llvm {
}
}
bool operator==(const SDep &Other) const {
if (Dep != Other.Dep || Latency != Other.Latency) return false;
/// Return true if the specified SDep is equivalent except for latency.
bool overlaps(const SDep &Other) const {
if (Dep != Other.Dep) return false;
switch (Dep.getInt()) {
case Data:
case Anti:
@ -133,6 +134,10 @@ namespace llvm {
llvm_unreachable("Invalid dependency kind!");
}
bool operator==(const SDep &Other) const {
return overlaps(Other) && Latency == Other.Latency;
}
bool operator!=(const SDep &Other) const {
return !operator==(Other);
}

23
lib/CodeGen/ScheduleDAG.cpp
View File

@ -64,10 +64,27 @@ const MCInstrDesc *ScheduleDAG::getNodeDesc(const SDNode *Node) const {
/// specified node.
bool SUnit::addPred(const SDep &D) {
// If this node already has this depenence, don't add a redundant one.
for (SmallVector<SDep, 4>::const_iterator I = Preds.begin(), E = Preds.end();
I != E; ++I)
if (*I == D)
for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end();
I != E; ++I) {
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 (SmallVector<SDep, 4>::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);