[PATCH] D67155: [InstCombine] Fold sub (and A, B) (or A, B)) to not (xor A, B)

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 created this revision.
xbolva00 added a reviewer: lebedev.ri.
Herald added a project: LLVM.
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  Name: sub(and(x, y), or(x, y)) -> neg(xor(x, y))
  %or = or i32 %y, %x
  %and = and i32 %x, %y
  %sub = sub i32 %and, %or
    =>
  %sub1 = xor i32 %x, %y
  %sub = sub i32 0, %sub1
  
  Optimization: sub(and(x, y), or(x, y)) -> neg(xor(x, y))
  Done: 1
  Optimization is correct!

https://rise4fun.com/Alive/VI6

Found by @lebedev.ri. Also author of the proof.


Repository:
  rL LLVM

https://reviews.llvm.org/D67155

Files:
  lib/Transforms/InstCombine/InstCombineAddSub.cpp
  test/Transforms/InstCombine/sub-and-or-not-xor.ll

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