diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Transforms/Scalar/LoopStrengthReduce.cpp | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index cc5da5d..1955fa5 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -1529,6 +1529,15 @@ namespace { ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond, IVStrideUse* &CondUse, const SCEVHandle* &CondStride) { + // Forgo this transformation if the condition has multiple uses. This is + // over-conservative, but simpler than alternatives. It guards against + // comparisons with a use that occurs earlier than the add instruction for the + // new stride index. See + // test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness.ll + // for an example of this situation. + if (!Cond->hasOneUse()) + return Cond; + if (StrideOrder.size() < 2 || IVUsesByStride[*CondStride].Users.size() != 1) return Cond; @@ -1654,9 +1663,9 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond, RHS = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr, RHS, NewCmpTy); } // Insert new compare instruction. - Cond = new ICmpInst(Predicate, NewIncV, RHS); - Cond->setName(L->getHeader()->getName() + ".termcond"); - OldCond->getParent()->getInstList().insert(OldCond, Cond); + Cond = new ICmpInst(Predicate, NewIncV, RHS, + L->getHeader()->getName() + ".termcond", + OldCond); // Remove the old compare instruction. The old indvar is probably dead too. DeadInsts.insert(cast<Instruction>(CondUse->OperandValToReplace)); |