1 files changed, 18 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
index e522d2f617d8..03112c67dda7 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
@@ -2097,6 +2097,24 @@ bool LoopVectorizationLegality::canFoldTailByMasking() const {
   for (const auto &Reduction : getReductionVars())
     ReductionLiveOuts.insert(Reduction.second.getLoopExitInstr());
 
+  // TODO: handle non-reduction outside users when tail is folded by masking.
+  for (auto *AE : AllowedExit) {
+    // Check that all users of allowed exit values are inside the loop or
+    // are the live-out of a reduction.
+    if (ReductionLiveOuts.count(AE))
+      continue;
+    for (User *U : AE->users()) {
+      Instruction *UI = cast<Instruction>(U);
+      if (TheLoop->contains(UI))
+        continue;
+      LLVM_DEBUG(
+          dbgs()
+          << "LV: Cannot fold tail by masking, loop has an outside user for "
+          << *UI << "\n");
+      return false;
+    }
+  }
+
   for (const auto &Entry : getInductionVars()) {
     PHINode *OrigPhi = Entry.first;
     for (User *U : OrigPhi->users()) {