If branch conditions' one successor is dominating another non-latch successor then this loop's iteration space can not be restricted. In this example block bb5 is always executed.
llvm-svn: 65902
diff --git a/llvm/lib/Transforms/Scalar/LoopIndexSplit.cpp b/llvm/lib/Transforms/Scalar/LoopIndexSplit.cpp
index 6311e17..e93d448 100644
--- a/llvm/lib/Transforms/Scalar/LoopIndexSplit.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIndexSplit.cpp
@@ -532,6 +532,21 @@
BasicBlock *ExitingBlock = ExitCondition->getParent();
if (!cleanBlock(ExitingBlock)) return false;
+ // If the merge point for BR is not loop latch then skip this loop.
+ if (BR->getSuccessor(0) != Latch) {
+ DominanceFrontier::iterator DF0 = DF->find(BR->getSuccessor(0));
+ assert (DF0 != DF->end() && "Unable to find dominance frontier");
+ if (!DF0->second.count(Latch))
+ return false;
+ }
+
+ if (BR->getSuccessor(1) != Latch) {
+ DominanceFrontier::iterator DF1 = DF->find(BR->getSuccessor(1));
+ assert (DF1 != DF->end() && "Unable to find dominance frontier");
+ if (!DF1->second.count(Latch))
+ return false;
+ }
+
// Verify that loop exiting block has only two predecessor, where one pred
// is split condition block. The other predecessor will become exiting block's
// dominator after CFG is updated. TODO : Handle CFG's where exiting block has