1 files changed, 6 insertions, 2 deletions
diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index 0d910d1..4f6ab06 100644
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -3818,9 +3818,13 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
       // Check if we found the exit user.
       BasicBlock *Parent = Usr->getParent();
       if (!TheLoop->contains(Parent)) {
-        // Exit if you find multiple outside users.
-        if (ExitInstruction != 0)
+        // Exit if you find multiple outside users or if the header phi node is
+        // being used. In this case the user uses the value of the previous
+        // iteration, in which case we would loose "VF-1" iterations of the
+        // reduction operation if we vectorize.
+        if (ExitInstruction != 0 || Cur == Phi)
           return false;
+
         ExitInstruction = Cur;
         continue;
       }