[PATCH] D62963: [DAGCombine] GetNegatedExpression - constant float vector support (PR42105)

[Cameron McInally via Phabricator via llvm-commits]

cameron.mcinally added a comment.

> I haven't enabled handling of undefs in build vector - but can anyone think of a reason that I shouldn't?

Yeah, I think undef should be handled. InstSimplify (and other IR passes IIRC) do it:

  define <2 x float> @fsub_-0_-0_x_vec_undef_elts(<2 x float> %a) {
  ; CHECK-LABEL: @fsub_-0_-0_x_vec_undef_elts(
  ; CHECK-NEXT:    ret <2 x float> [[A:%.*]]
  ;
    %t1 = fsub <2 x float> <float undef, float -0.0>, %a
    %ret = fsub <2 x float> <float -0.0, float undef>, %t1
    ret <2 x float> %ret
  }


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  rL LLVM

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