[clang] [llvm] [llvm-profgen] Add Arm SPE branch profile support (PR #223237)

[Sergey Shcherbinin via cfe-commits]

SergeyShch01 wrote:

@snehasish,

>Have you tested this end to end on a benchmark suite like SPEC?

Yes. I tested the complete workflow on SPEC CPU 2017. The binaries optimized with SPE-generated profiles showed performance comparable to those optimized with BRBE-generated profiles.

> I think we should document this support in https://clang.llvm.org/docs/UsersManual.html#using-sampling-profilers and include the settings users should use just like existing perf invocation.

Done. I added the Arm SPE recording command, requirements, and the corresponding llvm-profgen invocation to the manual.

https://github.com/llvm/llvm-project/pull/223237