[llvm] [RISCV] Remove CalleeSavedInfo for Zcmp/save-restore-libcalls registers (PR #79535)

[Visoiu Mistrih Francis via llvm-commits]

francisvm wrote:

> Thanks! I have a question: Does ARM have the same issue as it has PUSH/POP? How does it handle these CSIs?

No, it doesn't have this issue. The issue here is that in MFI, there are no real stack objects created for these CSR spills, which is what a frame index is supposed to point to. In the other backends, they get real stack objects with frame indices that are not pre-defined, which is what we should probably do here too. I did try to fix it properly but there are too many assumptions made around the current mode that makes it a little harder to fix for me.

https://github.com/llvm/llvm-project/pull/79535