[PATCH] D137060: [SCEV] Make isKnownOnEveryIteration return false if LHS's start value is not available at loop entry

[luxufan via Phabricator via llvm-commits]

StephenFan created this revision.
StephenFan added reviewers: nikic, fhahn, reames, mkazantsev.
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Fixes https://github.com/llvm/llvm-project/issues/58662


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D137060

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp


Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -10718,7 +10718,11 @@
                                               const SCEVAddRecExpr *LHS,
                                               const SCEV *RHS) {
   const Loop *L = LHS->getLoop();
-  return isLoopEntryGuardedByCond(L, Pred, LHS->getStart(), RHS) &&
+  const SCEV *Start = LHS->getStart();
+  if (!isAvailableAtLoopEntry(Start, L))
+    return false;
+
+  return isLoopEntryGuardedByCond(L, Pred, Start, RHS) &&
          isLoopBackedgeGuardedByCond(L, Pred, LHS->getPostIncExpr(*this), RHS);
 }
 


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