[PATCH] D58877: [InstCombine] fold add(add(A, ~B), 1) -> sub(A, B)

[Amaury SECHET via Phabricator via llvm-commits]

deadalnix added a comment.

@spatel I'm not sure, you tell me :) The history of this patch is that this pattern shows up in practice post legalization, so I submitted a patch for it for DAGCombiner. From there, @ lebedev.ri noticed that InstCombine wasn't doing it and suggested it to be added there as well.

As far as I can tell, -reassociate also fails to trigger this transform: https://godbolt.org/z/gweK6j


Repository:
  rL LLVM

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