[PATCH] D112955: [InstCombine] (~(a | b) & c) | ~(c | (a ^ b)) -> (a & b & ~c) | ~(a | b)

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec planned changes to this revision.
rampitec added a comment.

In the light of D113526 <https://reviews.llvm.org/D113526> this needs to be rebased and handle inverted pattern:

  (a | ~(b & c)) & ~(a & (b ^ c)) --> ~(a | b) | (a ^ b ^ c)

  ----------------------------------------
  define i4 @src(i4 %a, i4 %b, i4 %c) {
  %0:
    %and1 = and i4 %b, %c
    %not1 = xor i4 %and1, 15
    %or1 = or i4 %not1, %a
    %xor1 = xor i4 %b, %c
    %and2 = and i4 %xor1, %a
    %not2 = xor i4 %and2, 15
    %and3 = and i4 %or1, %not2
    ret i4 %and3
  }
  =>
  define i4 @tgt(i4 %a, i4 %b, i4 %c) {
  %0:
    %xor1 = xor i4 %b, %c
    %xor2 = xor i4 %xor1, %a
    %or1 = or i4 %a, %b
    %not1 = xor i4 %or1, 15
    %or2 = or i4 %xor2, %not1
    ret i4 %or2
  }
  Transformation seems to be correct!


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D112955/new/

https://reviews.llvm.org/D112955