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Ensure that def-side physreg copies are scheduled above any other uses

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so the scheduler can't create new interferences on the copies
themselves. Prior to this fix the scheduler could get stuck in a loop
creating copies.
Fixes PR9509.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128164 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2011-03-23 20:42:39 +00:00
parent 0d93a110e3
commit bd47a4a307
1 changed files with 9 additions and 0 deletions
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9
lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
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@ -935,6 +935,15 @@ void ScheduleDAGRRList::InsertCopiesAndMoveSuccs(SUnit *SU, unsigned Reg,
AddPred(SuccSU, D);
DelDeps.push_back(std::make_pair(SuccSU, *I));
}
else {
// Avoid scheduling the def-side copy before other successors. Otherwise
// we could introduce another physreg interference on the copy and
// continue inserting copies indefinitely.
SDep D(CopyFromSU, SDep::Order, /*Latency=*/0,
/*Reg=*/0, /*isNormalMemory=*/false,
/*isMustAlias=*/false, /*isArtificial=*/true);
AddPred(SuccSU, D);
}
}
for (unsigned i = 0, e = DelDeps.size(); i != e; ++i)
RemovePred(DelDeps[i].first, DelDeps[i].second);