[llvm] [llvm] Support multiple save/restore points in mir (PR #119357)

[Elizaveta Noskova via llvm-commits]

enoskova-sc wrote:

@michaelmaitland, do you want me to update this MR, adding information about registers, or should we wait for @preames to leave an opinion?

https://github.com/llvm/llvm-project/pull/119357