[clang] [Clang][perf-training] Do build of libLLVMSupport for perf training (PR #111625)

[Aiden Grossman via cfe-commits]

https://github.com/boomanaiden154 commented:

This looks very interesting!

Thanks for taking the time to collect all the numbers. It definitely seems like collecting proper profiles for BOLT is something that we want to do, at least for the CI compiler, given the numbers here.

I'm assuming you used instrumented BOLT here? Also, do you have numbers on how long the perf training took?

As an aside, we have some stuff in the pipeline to bring bigger self-hosted runners to Github actions. Once we get that going, I'm hoping to simplify the CI compiler build (unify the builds into one stage), and we should have some extra build time to do things like do perf-training for BOLT on all of LLVM/libLLVMSupport.

https://github.com/llvm/llvm-project/pull/111625