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| author | Dan Gohman <gohman@apple.com> | 2010-08-11 00:12:36 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2010-08-11 00:12:36 +0000 |
| commit | 4ee87398e808534577ed1be52f2b48a6130b2c0e (patch) | |
| tree | 3b7d7b376ae3bf2e509f3096354dd7664b74b823 /lib | |
| parent | f4452c37d03ab6cdcd2b23cb15b921c0bba591a7 (diff) | |
| download | llvm-4ee87398e808534577ed1be52f2b48a6130b2c0e.tar.gz llvm-4ee87398e808534577ed1be52f2b48a6130b2c0e.tar.bz2 llvm-4ee87398e808534577ed1be52f2b48a6130b2c0e.tar.xz | |
When analyzing loop exit conditions combined with and and or, don't
make any assumptions about when the two conditions will agree on when
to permit the loop to exit. This fixes PR7845.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110758 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 26 |
1 files changed, 12 insertions, 14 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index f5a762af82..b3ddfc032f 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -3854,14 +3854,13 @@ ScalarEvolution::ComputeBackedgeTakenCountFromExitCond(const Loop *L, else MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max); } else { - // Both conditions must be true for the loop to exit. + // Both conditions must be true at the same time for the loop to exit. + // For now, be conservative. assert(L->contains(FBB) && "Loop block has no successor in loop!"); - if (BTI0.Exact != getCouldNotCompute() && - BTI1.Exact != getCouldNotCompute()) - BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact); - if (BTI0.Max != getCouldNotCompute() && - BTI1.Max != getCouldNotCompute()) - MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max); + if (BTI0.Max == BTI1.Max) + MaxBECount = BTI0.Max; + if (BTI0.Exact == BTI1.Exact) + BECount = BTI0.Exact; } return BackedgeTakenInfo(BECount, MaxBECount); @@ -3889,14 +3888,13 @@ ScalarEvolution::ComputeBackedgeTakenCountFromExitCond(const Loop *L, else MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max); } else { - // Both conditions must be false for the loop to exit. + // Both conditions must be false at the same time for the loop to exit. + // For now, be conservative. assert(L->contains(TBB) && "Loop block has no successor in loop!"); - if (BTI0.Exact != getCouldNotCompute() && - BTI1.Exact != getCouldNotCompute()) - BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact); - if (BTI0.Max != getCouldNotCompute() && - BTI1.Max != getCouldNotCompute()) - MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max); + if (BTI0.Max == BTI1.Max) + MaxBECount = BTI0.Max; + if (BTI0.Exact == BTI1.Exact) + BECount = BTI0.Exact; } return BackedgeTakenInfo(BECount, MaxBECount); |