Enable Profile-Guided Optimization (PGO) for more packages

[zamazan4ik]

Hi!

Profile-Guided Optimization (PGO) is already enabled for several packages in the MinGW repo: Clang, GCC. Since PGO improves performance, I suggest enabling PGO for the following packages as well:

• Rust: Rust Lang blog
• Julia: GitHub PR
• SWI-Prolog: GitHub comment
• Go: Go compiler performance numbers

Probably there are other packages in the MinGW repo that can benefit from PGO. You can find the existing benchmarks for other projects here. Maybe we even want to integrate PGO into the packages like Ruby, Perl, and other similar packages.

[lazka]

Helpful links, thanks!

[RivenSkaye]

For linkers and compilers this makes a lot of sense, but for more general things like Ruby or Python which allow both execution or interactive REPL, the performance might be negatively impacted in use-cases other than what is simulated for PGO.
The alternative is running a lot of different uses for profiling which will take way more time to run and lower the overall performance gain.

PGO is, unfortunately, not a magical performance enhancement. It just provides benefits for the code paths used a lot with instrumentation and penalizes the paths instrumentation didn't touch.
I'd say look at packages case by case to determine if it's worth the tradeoff there