[llvm] [MCA] New option to report scheduling information: -scheduling-info (PR #126703)

[Min-Yih Hsu via llvm-commits]

https://github.com/mshockwave commented:

> I must agree with @boomanaiden154 on this - I'd expect a better approach to be to generate llvm-exegesis yaml for each instruction and use the analysis tools to compare against the scheduler models.

Majority of the RISCV MCA test are actually there to make sure our TableGen changes on scheduling models reflect correctly, especially on vector instructions which use lots of non-trivial TableGen machinery. 

So while I agree that a llvm-exegesis-generated YAML should be a better golden reference for scheduling models, I think the existing MCA tests still have their values.

In general, I think printing just `<uOps>, <Latency>, <Bypass Latency>, <Throughput>, <Resources units>` for scheduling model tests makes sense to me, as the MCA view we use in scheduling model tests right now is a little too verbose.
But I would expect `update_mca_tests_checks.py` to generate something like
```
// CHECK: <uOps>, <Latency>, <Bypass Latency>, <Throughput>, <Resources units>
```
Which effectively does the same things as the current scheduling model tests, that is, doing the validation as part of the test, rather than doing the validation using the script via `--check-sched-info` as you propose.

https://github.com/llvm/llvm-project/pull/126703