[PATCH] D147355: [LV] Optimize trip count SCEV.

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:1005
+        SE.getAddExpr(BackedgeTakenCount,
+                      SE.getOne(BackedgeTakenCount->getType()), SCEV::FlagNUW),
+        IdxTy);
----------------
reames wrote:
> I don't believe the flags usage here is correct.  There's a single SCEV node for an add with given operands.  The flags must be correct for all users of that add expression, and for a loop invariant trip count there's nothing preventing another use outside the loop which does overflow.
Is the usage in LoopIdiomRecognize wrong too?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D147355/new/

https://reviews.llvm.org/D147355