[clang] [llvm] [NVPTX] Support __usAtomicCAS builtin (PR #99646)

[via llvm-commits]

DenisGZM wrote:

Sorry, haven't ever run these tests before.
Ok, I got that I should add predicates for SM and PTX versions in backend. Adjust min size of cmpxchng depending on sm and ptx version.
But still one test for sm_90 is failing, because expect another code... Should I just rewrite it? Is that how it's done? :)

https://github.com/llvm/llvm-project/pull/99646