[PATCH] D142427: [ValueTracking] Add logic for tracking lowbit of (and/xor/or X, (add/sub X, Odd))

[Noah Goldstein via Phabricator via llvm-commits]

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Any case of logicop + add/sub(Odd) we can prove the low bit is either
zero/non-zero.

Alive2 Links:

  xor:
      sub x, C: https://alive2.llvm.org/ce/z/aaABdS
      sub C, x: https://alive2.llvm.org/ce/z/2W-ZJ7
      add C, x: https://alive2.llvm.org/ce/z/pzDkte
  or:
      sub x, C: https://alive2.llvm.org/ce/z/xd-bcP
      sub C, x: https://alive2.llvm.org/ce/z/p8hXJF
      add C, x: https://alive2.llvm.org/ce/z/osmkB6
  and:
      sub x, C: https://alive2.llvm.org/ce/z/D_NNxR
      sub C, x: https://alive2.llvm.org/ce/z/N_5C62
      add C, x: https://alive2.llvm.org/ce/z/4cy7a4


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D142427

Files:
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/test/Analysis/ValueTracking/knownbits-and-or-xor-lowbit.ll
  llvm/test/Analysis/ValueTracking/knownbits-bmi-pattern.ll

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