[llvm] [RISCV] Add scheduler definitions for SpacemiT-X60 (PR #137343)

[Mark Zhuang via llvm-commits]

zqb-all wrote:

> From context in offline discussion, this was an ad-hoc mix of llvm-exegesis where it seemed to produce sane results, and custom assembly snippets.
> 
> There's definitely room for error here; this type of micro-architectural exploration is hard and error prone. I approved this mostly based on the net perf results, not any expectation that every number for every instruction was correct.
> 
> I'd encourage you to make suggestions for improvements. Ideally in the form of pull requests, but if you want to drop comments here, Mikhail or I can follow up.

Thanks, I don't mean to question a certain number in this configuration., this patch is good.

 I just want to learn this way of probing, so that it will also be helpful when improving the configuration in the future.

https://github.com/llvm/llvm-project/pull/137343