[llvm] [AArch64] Fix return address auth in swiftasync epilogues (PR #189484)

[Jon Roelofs via llvm-commits]

jroelofs wrote:

> > We either need to find that and upstream it or accept this patch and accept the inevitable merge conflicts, but we shouldn't hold this up indefinitely.
> 
> Let's move forward with this patch. I can deal with those merge conflicts, and see about upstreaming any remaining stragglers in this neighborhood.

Follow-up for that here: https://github.com/llvm/llvm-project/pull/203340/changes

https://github.com/llvm/llvm-project/pull/189484