[llvm] [NVPTX] Rework and cleanup FTZ ISel (PR #146410)

[Artem Belevich via llvm-commits]

Artem-B wrote:

> This change cleans up DAG-to-DAG instruction selection around FTZ and SETP comparison mode. Largely this is non-functional though support for {sin.cos}.approx.ftz.f32 is added.

Is "Non-functional" as in "does not work" or did you mean "no functional changes" ?

https://github.com/llvm/llvm-project/pull/146410