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mi-sched: improve the generic register pressure comparison.

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Only compare pressure within the same set. When multiple sets are
affected, we prioritize the most constrained set.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189641 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick
2013-08-30 04:27:29 +00:00
parent 4c60b8a78d
commit da6fc15f0f
5 changed files with 29 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/CodeGen/MachineScheduler.cpp
+12 -14
View File
@@ -2182,21 +2182,19 @@ static bool tryPressure(const PressureChange &TryP,
ConvergingScheduler::SchedCandidate &TryCand,
ConvergingScheduler::SchedCandidate &Cand,
ConvergingScheduler::CandReason Reason) {
if (TryP.isValid() && CandP.isValid()) {
// If both candidates affect the same set, go with the smallest increase.
if (TryP.getPSet() == CandP.getPSet()) {
return tryLess(TryP.getUnitInc(), CandP.getUnitInc(), TryCand, Cand,
Reason);
}
// If one candidate decreases and the other increases, go with it.
if (tryLess(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand,
Reason)) {
return true;
}
int TryRank = TryP.getPSetOrMax();
int CandRank = CandP.getPSetOrMax();
// If both candidates affect the same set, go with the smallest increase.
if (TryRank == CandRank) {
return tryLess(TryP.getUnitInc(), CandP.getUnitInc(), TryCand, Cand,
Reason);
}
// If one candidate decreases and the other increases, go with it.
// Invalid candidates have UnitInc==0.
if (tryLess(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand,
Reason)) {
return true;
}
// If TryP has lower Rank, it has a higher priority.
int TryRank = TryP.getRank();
int CandRank = CandP.getRank();
// If the candidates are decreasing pressure, reverse priority.
if (TryP.getUnitInc() < 0)
std::swap(TryRank, CandRank);