[llvm] [SystemZ] Don't lower float/double ATOMIC_[LOAD|STORE] to [LOAD|STORE] (PR #75879)

[Jonas Paulsson via llvm-commits]

JonPsson1 wrote:

> The generic bits lgtm. The systemZ handling is a hack, and we'd still be better off getting rid of ATOMIC_LOAD and following how GlobalISel does this

Thanks for review! Before committing, I think I will try to get rid of the hack in SystemZ and use PatFrags there instead. I will also make a note somewhere that ATOMIC_LOAD might removed at some point.

https://github.com/llvm/llvm-project/pull/75879