diff --git a/lib/Transforms/Scalar/LoopIndexSplit.cpp b/lib/Transforms/Scalar/LoopIndexSplit.cpp index 980990ea652..9b4319d40cd 100644 --- a/lib/Transforms/Scalar/LoopIndexSplit.cpp +++ b/lib/Transforms/Scalar/LoopIndexSplit.cpp @@ -711,12 +711,22 @@ bool LoopIndexSplit::splitLoop(SplitInfo &SD) { || Latch == SplitTerminator->getSuccessor(1))) return false; - + // If one of the split condition branch is post dominating other then loop + // index split is not appropriate. BasicBlock *Succ0 = SplitTerminator->getSuccessor(0); BasicBlock *Succ1 = SplitTerminator->getSuccessor(1); if (DT->dominates(Succ0, Latch) || DT->dominates(Succ1, Latch)) return false; + // If one of the split condition branch is a predecessor of the other + // split condition branch head then do not split loop on this condition. + for(pred_iterator PI = pred_begin(Succ0), PE = pred_end(Succ0); PI != PE; ++PI) + if (Succ1 == *PI) + return false; + for(pred_iterator PI = pred_begin(Succ1), PE = pred_end(Succ1); PI != PE; ++PI) + if (Succ0 == *PI) + return false; + // True loop is original loop. False loop is cloned loop. bool SignedPredicate = ExitCondition->isSignedPredicate();