[llvm] [Exegesis][RISCV] Add RISCV support for llvm-exegesis (PR #89047)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> I saw you removed the perf counters tuff, do you plan to send a separate PR for that? Without libpfm support for riscv, I can't test the PR.

The perf counter stuff has been taken out and will be added later (from what I understand).

libpfm as far as I'm aware does support the generic perf counters (I forget the names) that you should be able to wire up pretty easily.

@mshockwave was planning on upstreaming support for using the raw event encodings rather than using libpfm to get performance counters actually working on RISCV within `llvm-exegesis`. That shouldn't be too complicated to get working either. The code for that is available in #114149.

https://github.com/llvm/llvm-project/pull/89047