[PATCH] D85463: [GlobalISel] Add combine for (x & mask) -> x when (x & mask) == x

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

Where is this handled in DAGCombiner? I don't see anything directly matching this; is this one of the cases that SimplifyDemandedBits handles more generally? The closest looking thing after skimming is this:

  // if (and x, c) is known to be zero, return 0
  unsigned BitWidth = VT.getScalarSizeInBits();
  if (N1C && DAG.MaskedValueIsZero(SDValue(N, 0),
                                   APInt::getAllOnesValue(BitWidth)))
    return DAG.getConstant(0, SDLoc(N), VT);


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D85463/new/

https://reviews.llvm.org/D85463