diff options
author | James Molloy <james.molloy@arm.com> | 2015-05-15 12:17:22 +0000 |
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committer | James Molloy <james.molloy@arm.com> | 2015-05-15 12:17:22 +0000 |
commit | 39a7d6e91d51a9f5e5d24e007cb4d9fe92114cb3 (patch) | |
tree | 5cf29a4a3ac62668e27356c7905a934faf393cc8 /lib/Analysis/DependenceAnalysis.cpp | |
parent | 039eb5a7b85543d4f6e09e7f377124309245108e (diff) |
[DependenceAnalysis] Fix for PR21585: collectUpperBound triggers asserts
collectUpperBound hits an assertion when the back edge count is wider then the desired type.
If that happens, truncate the backedge count.
Patch by Philip Pfaffe!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237439 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis/DependenceAnalysis.cpp')
-rw-r--r-- | lib/Analysis/DependenceAnalysis.cpp | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/lib/Analysis/DependenceAnalysis.cpp b/lib/Analysis/DependenceAnalysis.cpp index 3374b48c141..808a38b6346 100644 --- a/lib/Analysis/DependenceAnalysis.cpp +++ b/lib/Analysis/DependenceAnalysis.cpp @@ -830,6 +830,14 @@ bool DependenceAnalysis::checkSrcSubscript(const SCEV *Src, return isLoopInvariant(Src, LoopNest); const SCEV *Start = AddRec->getStart(); const SCEV *Step = AddRec->getStepRecurrence(*SE); + const SCEV *UB = SE->getBackedgeTakenCount(AddRec->getLoop()); + if (!isa<SCEVCouldNotCompute>(UB)) { + if (SE->getTypeSizeInBits(Start->getType()) < + SE->getTypeSizeInBits(UB->getType())) { + if (!AddRec->getNoWrapFlags()) + return false; + } + } if (!isLoopInvariant(Step, LoopNest)) return false; Loops.set(mapSrcLoop(AddRec->getLoop())); @@ -848,6 +856,14 @@ bool DependenceAnalysis::checkDstSubscript(const SCEV *Dst, return isLoopInvariant(Dst, LoopNest); const SCEV *Start = AddRec->getStart(); const SCEV *Step = AddRec->getStepRecurrence(*SE); + const SCEV *UB = SE->getBackedgeTakenCount(AddRec->getLoop()); + if (!isa<SCEVCouldNotCompute>(UB)) { + if (SE->getTypeSizeInBits(Start->getType()) < + SE->getTypeSizeInBits(UB->getType())) { + if (!AddRec->getNoWrapFlags()) + return false; + } + } if (!isLoopInvariant(Step, LoopNest)) return false; Loops.set(mapDstLoop(AddRec->getLoop())); @@ -942,13 +958,15 @@ bool DependenceAnalysis::isKnownPredicate(ICmpInst::Predicate Pred, // All subscripts are all the same type. // Loop bound may be smaller (e.g., a char). // Should zero extend loop bound, since it's always >= 0. -// This routine collects upper bound and extends if needed. +// This routine collects upper bound and extends or truncates if needed. +// Truncating is safe when subscripts are known not to wrap. Cases without +// nowrap flags should have been rejected earlier. // Return null if no bound available. const SCEV *DependenceAnalysis::collectUpperBound(const Loop *L, Type *T) const { if (SE->hasLoopInvariantBackedgeTakenCount(L)) { const SCEV *UB = SE->getBackedgeTakenCount(L); - return SE->getNoopOrZeroExtend(UB, T); + return SE->getTruncateOrZeroExtend(UB, T); } return nullptr; } |