[llvm] [AArch64] Update the scheduling model for Cortex-X1/2/3/4 (PR #118826)

[David Green via llvm-commits]

davemgreen wrote:

Thanks

> LGTM, nice. How much extra performance (roughly) does this provide?

Scheduling on OoO machines doesn't usually give a lot of performance, when taken as an aggregate. The OoO machines can do a lot of scheduling themselves so long as we get it close enough, and my tests it was not very much. This is closer in terms of the correct number of pipelines though, which would help if we start to use them more.

https://github.com/llvm/llvm-project/pull/118826