[clang] [llvm] [RISCV][clang] Support XSfmm ABI attributes (PR #206260)

[Brandon Wu via llvm-commits]

4vtomat wrote:

I added a pass in very late machine instruction state that checks if any unexpected call is generated, I just filter out the calls that is marked as frame setup/destroy which is guaranteed to not touching any riscv state. I think we can probably have a white list to skip.

https://github.com/llvm/llvm-project/pull/206260