[llvm] [llvm] Add support for llvm IR atomicrmw fminimum/fmaximum instructions (PR #136759)

[Jonathan Thackray via llvm-commits]

jthackray wrote:

> LGTM. Only thing that appears to be missing is the main codegen bits, but best to leave that for the next patch

Thanks. Yes, I've got a couple of follow-on patches planned.

https://github.com/llvm/llvm-project/pull/136759