[llvm] [InstCombine] Preserve the sign bit of NaN in `SimplifyDemandedUseFPClass` (PR #137287)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

Looks fine, but I don't think there is enough coverage for the new FMF handling? ninf is untested.

https://github.com/llvm/llvm-project/pull/137287