[llvm] SelectionDAG: Expand fminimumnum/fmaximumnum for promote (PR #135614)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Hi. For FMINNUM_IEEE, without -mattr=+fullfp16 I would expect this to promote as with other similar operations (see line 800).  If it had fullfp16 then it would should be legal, which I believe it already is.

If we need to expand a FMINIMUMNUM I would expect it to expand in the same way. It seems to be OK for +fullfp16 at the moment: https://godbolt.org/z/PsrW5EanW.

https://github.com/llvm/llvm-project/pull/135614