[clang] [llvm] [Transforms][Utils][PromoteMem2Reg] Propagate nnan flag on par with the nsz flag (PR #114271)

[Nikita Popov via cfe-commits]

https://github.com/nikic commented:

We should probably also handle `no-infs-fp-math` to save the next person the trouble.

https://github.com/llvm/llvm-project/pull/114271