[llvm] [DirectX] Add support to lower LLVM intrinsics ceil, cos, fabs, and floor to DXIL Ops. (PR #80350)

[Chris B via llvm-commits]

https://github.com/llvm-beanz commented:

I had some general comments about the tablegen representations. Since the goal is that this tablegen file eventually becomes the source of truth for defining DXIL it would be nice if the file was more explicit and needed fewer magic decoder rings to understand.

https://github.com/llvm/llvm-project/pull/80350