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
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 13c7340..20b2aa4 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2619,10 +2619,15 @@
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 @@
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;