Craig Topper df76ff98e8 [InstCombine][LV] Fold (add (zext (add X, -1)), 1) -> (zext X) if X is non-zero. ...

This artifact can appear from the vectorizer. (add X, -1) is the
backedge taken count. It gets zero extended and then 1 is added to
it to get the trip count.

There is usually a dominating branch that rules out X being zero.

Alive: https://alive2.llvm.org/ce/z/NsRDwX

2023-01-30 17:45:01 -08:00

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