1 files changed, 23 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index c20b1bd..ce4d4ad 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -14952,6 +14952,29 @@ const SCEVAddRecExpr *ScalarEvolution::convertSCEVToAddRecWithPredicates(
   if (!AddRec)
     return nullptr;
 
+  // Check if any of the transformed predicates is known to be false. In that
+  // case, it doesn't make sense to convert to a predicated AddRec, as the
+  // versioned loop will never execute.
+  for (const SCEVPredicate *Pred : TransformPreds) {
+    auto *WrapPred = dyn_cast<SCEVWrapPredicate>(Pred);
+    if (!WrapPred || WrapPred->getFlags() != SCEVWrapPredicate::IncrementNSSW)
+      continue;
+
+    const SCEVAddRecExpr *AddRecToCheck = WrapPred->getExpr();
+    const SCEV *ExitCount = getBackedgeTakenCount(AddRecToCheck->getLoop());
+    if (isa<SCEVCouldNotCompute>(ExitCount))
+      continue;
+
+    const SCEV *Step = AddRecToCheck->getStepRecurrence(*this);
+    if (!Step->isOne())
+      continue;
+
+    ExitCount = getTruncateOrSignExtend(ExitCount, Step->getType());
+    const SCEV *Add = getAddExpr(AddRecToCheck->getStart(), ExitCount);
+    if (isKnownPredicate(CmpInst::ICMP_SLT, Add, AddRecToCheck->getStart()))
+      return nullptr;
+  }
+
   // Since the transformation was successful, we can now transfer the SCEV
   // predicates.
   Preds.append(TransformPreds.begin(), TransformPreds.end());