[llvm] [Exegesis][RISCV] Support C_LDSP for llvm-exegesis (PR #169660)

[Shaoce SUN via llvm-commits]

sunshaoce wrote:

Thanks everyone for the guidance. I've now implemented the change to replace `rd` with `X2`. I think subprocess support can be implemented later.

https://github.com/llvm/llvm-project/pull/169660