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-rw-r--r--lib/Analysis/ScalarEvolution.cpp10
1 files changed, 4 insertions, 6 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 122dba3e6a..65cee82a96 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2527,19 +2527,17 @@ HowManyLessThans(SCEV *LHS, SCEV *RHS, const Loop *L, bool isSigned) {
if (AddRec->isAffine()) {
// The number of iterations for "{n,+,1} < m", is m-n. However, we don't
// know that m is >= n on input to the loop. If it is, the condition
- // returns true zero times. To handle both cases, we return SMAX(0, m-n).
+ // returns true zero times. To handle both cases, we return SMAX(m, n)-n.
// FORNOW: We only support unit strides.
SCEVHandle One = SE.getIntegerSCEV(1, RHS->getType());
if (AddRec->getOperand(1) != One)
return UnknownValue;
- SCEVHandle Iters = SE.getMinusSCEV(RHS, AddRec->getOperand(0));
+ SCEVHandle Start = AddRec->getOperand(0);
+ SCEVHandle End = isSigned ? SE.getSMaxExpr(RHS, Start) : (SCEVHandle)RHS;
- if (isSigned)
- return SE.getSMaxExpr(SE.getIntegerSCEV(0, RHS->getType()), Iters);
- else
- return Iters;
+ return SE.getMinusSCEV(End, Start);
}
return UnknownValue;