[llvm] [GlobalISel][TableGen] Take first result for multi-output instructions (PR #81130)

[Björn Pettersson via llvm-commits]

bjope wrote:

@Pierre-vh : Still nothing from @arsenm , so can I push this given your earlier LGTM?

I still think someone from AMDGPU could look in to cleaning up selectG_FABS/G_FNEG etc. after on this patch. I don't feel comfortable doing that.

But it is really annoying that this patch has been stalled since August 2020, even if AMD people have shown interest in getting it merged. And there has been LGTM:s with the only catch being that @arsenm must approve it, but @arsenm hasn't commented on it since October 2020.

https://github.com/llvm/llvm-project/pull/81130