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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96688 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-02-19 18:49:22 +00:00
parent 5dfa26795d
commit bc02853b89
1 changed files with 6 additions and 0 deletions
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6
lib/Analysis/ScalarEvolution.cpp
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@ -1973,6 +1973,12 @@ ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
return getAddRecExpr(Operands, L, HasNUW, HasNSW); // {X,+,0} --> X
}
// It's tempting to want to call getMaxBackedgeTakenCount count here and
// use that information to infer NUW and NSW flags. However, computing a
// BE count requires calling getAddRecExpr, so we may not yet have a
// meaningful BE count at this point (and if we don't, we'd be stuck
// with a SCEVCouldNotCompute as the cached BE count).
// If HasNSW is true and all the operands are non-negative, infer HasNUW.
if (!HasNUW && HasNSW) {
bool All = true;