[PATCH] D113216: [InstCombine] (~(a | b) & c) | ~(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)

  ----------------------------------------
  define i4 @src(i4 %a, i4 %b, i4 %c) {
  %0:
    %and1 = and i4 %c, %a
    %and2 = and i4 %and1, %b
    %not1 = xor i4 %and2, 15
    %and3 = and i4 %a, %b
    %not2 = xor i4 %and3, 15
    %or2 = or i4 %not2, %c
    %and4 = and i4 %or2, %not1
    ret i4 %and4
  }
  =>
  define i4 @tgt(i4 %a, i4 %b, i4 %c) {
  %0:
    %and = and i4 %a, %b
    %not = xor i4 %and, 15
    ret i4 %not
  }
  Transformation seems to be correct!


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D113216/new/

https://reviews.llvm.org/D113216