diff options
| author | Dan Gohman <gohman@apple.com> | 2009-07-21 00:42:47 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2009-07-21 00:42:47 +0000 |
| commit | a16b5764e3a39d37178864592d7bf7c483676079 (patch) | |
| tree | 60b2194d1ded616a358b6c8ad9deed3790959f45 /lib/Analysis/ScalarEvolution.cpp | |
| parent | c2b015e4c0151ca7144438afd98e6f7091656e5d (diff) | |
Make the range calculations for addrecs to be more conservative,
as they aren't currently prepared to handle complicated overflow
cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76524 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis/ScalarEvolution.cpp')
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 13c734027c..20b2aa48c1 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -2619,10 +2619,15 @@ ScalarEvolution::getUnsignedRange(const SCEV *S) { MaxBECount = getNoopOrZeroExtend(MaxBECount, Ty); const SCEV *Start = AddRec->getStart(); + const SCEV *Step = AddRec->getStepRecurrence(*this); const SCEV *End = AddRec->evaluateAtIteration(MaxBECount, *this); // Check for overflow. - if (!isKnownPredicate(ICmpInst::ICMP_ULE, Start, End)) + // TODO: This is very conservative. + if (!(Step->isOne() && + isKnownPredicate(ICmpInst::ICMP_ULT, Start, End)) && + !(Step->isAllOnesValue() && + isKnownPredicate(ICmpInst::ICMP_UGT, Start, End))) return FullSet; ConstantRange StartRange = getUnsignedRange(Start); @@ -2728,9 +2733,10 @@ ScalarEvolution::getSignedRange(const SCEV *S) { const SCEV *End = AddRec->evaluateAtIteration(MaxBECount, *this); // Check for overflow. - if (!(isKnownPositive(Step) && + // TODO: This is very conservative. + if (!(Step->isOne() && isKnownPredicate(ICmpInst::ICMP_SLT, Start, End)) && - !(isKnownNegative(Step) && + !(Step->isAllOnesValue() && isKnownPredicate(ICmpInst::ICMP_SGT, Start, End))) return FullSet; |