[llvm] [X86][LegalizeDAG] FPOWI: promote f16 operand (PR #105775)

[via llvm-commits]

v01dXYZ wrote:

I was worried than another Opcode presented the same problem (ie with LegalizeAction defaulting to Expand and spawning an assert when LegalizeDAG fallthroughs to libcall convertion). But it seems FPOWI is special, that's the only float Opcode in `ConvertNodeToLibcall` that checks for the libcall existence and if it does not exist fallbacks to using `FPOW`.

I have a vocabulary question: in the strict terminology of Legalisation, *expand* means breaking up a complex operation using smaller types, should I rather think of it as an Instruction Expand ? 

https://github.com/llvm/llvm-project/pull/105775