[llvm] [NFC] Add useFPRegsForHalfType(). (PR #74147)

[Harald van Dijk via llvm-commits]

hvdijk wrote:

> You need to update all the "SoftPromoteHalf..." functions in `llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp`.

Could you elaborate a bit on this? During testing with the aforementioned https://github.com/hvdijk/llvm-project/commit/softpromotehalf-fpreg-arm, things seemed to work. Are you imagining anything in particular that doesn't work?

https://github.com/llvm/llvm-project/pull/74147