[PATCH] D67799: [InstCombine] Fold a shifty implementation of clamp0.

[Huihui Zhang via Phabricator via llvm-commits]

huihuiz created this revision.
huihuiz added reviewers: lebedev.ri, efriedma, spatel, kparzysz, bcahoon.
huihuiz added a project: LLVM.
Herald added subscribers: hiraditya, kristof.beyls.

Fold

  and(ashr(sub(0, V), ScalarSizeInBits - 1), V)

into

  V s< 0 ? 0 : V

where sub hasNoSignedWrap.

https://rise4fun.com/Alive/ZNSs

Fold shift into select enable more optimization, e.g., vmax generation for ARM target.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D67799

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  llvm/test/Transforms/InstCombine/sub-ashr-and-to-icmp-select.ll

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