diff options
Diffstat (limited to 'llvm/lib/Transforms/Utils/SimplifyIndVar.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Utils/SimplifyIndVar.cpp | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp index 4ebafd8..6d90e6b 100644 --- a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp @@ -156,6 +156,7 @@ Value *SimplifyIndvar::foldIVUser(Instruction *UseInst, Instruction *IVOperand) void SimplifyIndvar::eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand) { unsigned IVOperIdx = 0; ICmpInst::Predicate Pred = ICmp->getPredicate(); + ICmpInst::Predicate OriginalPred = Pred; if (IVOperand != ICmp->getOperand(0)) { // Swapped assert(IVOperand == ICmp->getOperand(1) && "Can't find IVOperand"); @@ -264,6 +265,16 @@ void SimplifyIndvar::eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand) { ICmp->setPredicate(InvariantPredicate); ICmp->setOperand(0, NewLHS); ICmp->setOperand(1, NewRHS); + } else if (ICmpInst::isSigned(OriginalPred) && + SE->isKnownNonNegative(S) && SE->isKnownNonNegative(X)) { + // If we were unable to make anything above, all we can is to canonicalize + // the comparison hoping that it will open the doors for other + // optimizations. If we find out that we compare two non-negative values, + // we turn the instruction's predicate to its unsigned version. Note that + // we cannot rely on Pred here unless we check if we have swapped it. + assert(ICmp->getPredicate() == OriginalPred && "Predicate changed?"); + DEBUG(dbgs() << "INDVARS: Turn to unsigned comparison: " << *ICmp << '\n'); + ICmp->setPredicate(ICmpInst::getUnsignedPredicate(OriginalPred)); } else return; |