diff options
| author | Hal Finkel <hfinkel@anl.gov> | 2012-10-24 19:46:44 +0000 |
|---|---|---|
| committer | Hal Finkel <hfinkel@anl.gov> | 2012-10-24 19:46:44 +0000 |
| commit | 8c65549318950ff3fc1cb3d7a73fb50c688c78a5 (patch) | |
| tree | fd174875c34cec9db5e130538cb2e7ee02e40283 /lib/Analysis | |
| parent | 99abc17832b36007c66369321c0c2f5a2a7713f1 (diff) | |
| download | external_llvm-8c65549318950ff3fc1cb3d7a73fb50c688c78a5.zip external_llvm-8c65549318950ff3fc1cb3d7a73fb50c688c78a5.tar.gz external_llvm-8c65549318950ff3fc1cb3d7a73fb50c688c78a5.tar.bz2 | |
getSmallConstantTripMultiple should never return zero.
When the trip count is -1, getSmallConstantTripMultiple could return zero,
and this would cause runtime loop unrolling to assert. Instead of returning
zero, one is now returned (consistent with the existing overflow cases).
Fixes PR14167.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166612 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis')
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 3e06298..148912b 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -3979,8 +3979,11 @@ getSmallConstantTripMultiple(Loop *L, BasicBlock *ExitingBlock) { ConstantInt *Result = MulC->getValue(); - // Guard against huge trip counts. - if (!Result || Result->getValue().getActiveBits() > 32) + // Guard against huge trip counts (this requires checking + // for zero to handle the case where the trip count == -1 and the + // addition wraps). + if (!Result || Result->getValue().getActiveBits() > 32 || + Result->getValue().getActiveBits() == 0) return 1; return (unsigned)Result->getZExtValue(); |