[PATCH] D109457: [SCEV] Use constant range of RHS to prove NUW on narrow IV in trip count logic

[Philip Reames via Phabricator via llvm-commits]

reames added a comment.

ping - this has been outstanding for a while and is blocking progress for me, any chance I can get someone to review?

JFYI, all of the other approaches I've mentioned in the review thread so far have not panned out.  I can cover some cases with each, but not the motivating example.  This patch's use of mustprogress to disprove the infinite loop case is critical.  Every time I tried implementing this differently, I ended up just re-implementing this same idea without the infrastructure that SCEV already provides for this.  I think this really does have to be in SCEV's trip count logic.


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  https://reviews.llvm.org/D109457/new/

https://reviews.llvm.org/D109457