[llvm] [InstCombine] Add an additional nnan constraint for xfrm fcmp + sel => fmax/fmin (PR #117977)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

It doesn't look like the nnan is required, you just can't always preserve it? https://alive2.llvm.org/ce/z/4Dj45b

https://github.com/llvm/llvm-project/pull/117977