[PATCH] D110488: [InstCombine] Fold ctpop((x & -x ) - 1) -> cttz(x, false) (PR51784)

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a comment.

Having spoken to @spatel offline, I'm going to add a fold for ((x & -x ) - 1) -> (~x & (x - 1)) as well as the ctpop fold - this will require single/multiuse tests for the inner fold (where it shouldn't fold multiuses) and for the ctpop case (where it should always fold to cttz).


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D110488/new/

https://reviews.llvm.org/D110488