[PATCH] D132022: [SCEVExpander] Drop poison-generating flags on hoisting. PR57187

[Florian Hahn via Phabricator via llvm-commits]

fhahn added inline comments.


================
Comment at: llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp:1056
+    // Drop flags that are potentially inferred from old context.
+    I->dropPoisonGeneratingFlags();
   }
----------------
This seems too pessimistic and unnecessarily drops flags that are not inferred based on the context instruction, e.g. because the original IV already had `nuw/nsw`.

Would it be possible to preserve the flags valid at entry of the loop when hoisting?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D132022/new/

https://reviews.llvm.org/D132022