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

[Elizaveta Noskova via llvm-commits]

enoskova-sc wrote:

@preames, in this patch I suggest to support two formats of save points in MFI and reduce complexity (change tests) in the follow up patch.

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