[PATCH] D93906: [LoopDeletion] Break backedge of loops when known not taken

[Philip Reames via Phabricator via llvm-commits]

reames added a comment.

In D93906#2476680 <https://reviews.llvm.org/D93906#2476680>, @nikic wrote:

> Isn't this already covered by the zero exit count optimization in IndVars?

No.  I believe you're referring to optimizeLoopExits.  That does not modify the CFG, it just folds conditions to constants.  This will specifically modify the CFG and remove the loop.



================
Comment at: llvm/lib/Transforms/Utils/LoopUtils.cpp:774
+
+  std::unique_ptr<MemorySSAUpdater> MSSAU;
+  if (MSSA)
----------------
fhahn wrote:
> I realize this is similar to what is done in `deleteDeadLoop`, but MSSA is only passed so it can be kept up-to-date, right? Can we just pass a pointer to the updater instead (making the intended use more explicit and avoids a dynamic allocation here)
Not quite sure I follow your request here.  I'm happy to address this in a separate cleanup (if you clarify what you're looking for), but I'm going to land as is since the same pattern is already used in existing code.  


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93906/new/

https://reviews.llvm.org/D93906