LSR critical edge splitting fix for PR13756.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164147 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index bcd27b1..1d3d156 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -4464,17 +4464,21 @@
SplitLandingPadPredecessors(Parent, BB, "", "", P, NewBBs);
NewBB = NewBBs[0];
}
+ // If NewBB==NULL, then SplitCriticalEdge refused to split because all
+ // phi predecessors are identical. The simple thing to do is skip
+ // splitting in this case rather than complicate the API.
+ if (NewBB) {
+ // If PN is outside of the loop and BB is in the loop, we want to
+ // move the block to be immediately before the PHI block, not
+ // immediately after BB.
+ if (L->contains(BB) && !L->contains(PN))
+ NewBB->moveBefore(PN->getParent());
- // If PN is outside of the loop and BB is in the loop, we want to
- // move the block to be immediately before the PHI block, not
- // immediately after BB.
- if (L->contains(BB) && !L->contains(PN))
- NewBB->moveBefore(PN->getParent());
-
- // Splitting the edge can reduce the number of PHI entries we have.
- e = PN->getNumIncomingValues();
- BB = NewBB;
- i = PN->getBasicBlockIndex(BB);
+ // Splitting the edge can reduce the number of PHI entries we have.
+ e = PN->getNumIncomingValues();
+ BB = NewBB;
+ i = PN->getBasicBlockIndex(BB);
+ }
}
}