PGO optimization for non-Rust dependencies in Rust projects about cargo-pgo HOT 4 OPEN

I think that the mere existence of this issue is enough, if someone will look for PGO + native/C/C++ dependencies, they will find the discussion about it here :)

from cargo-pgo.

Hi, yeah, I agree that this would be quite difficult to support in the general case (although for specific crates it shouldn't be that hard). I'm not sure how we should document this though. "If you have native code, cargo-pgo won't PGO optimize it?". I'm not sure if that adds any relevant value, as cargo-pgo doesn't promise anything about C/C++ PGO optimizations.

from cargo-pgo.

In any case, if you have something specific in mind, I'd be happy to accept a PR :)

from cargo-pgo.

I agree that this would be quite difficult to support in the general case (although for specific crates it shouldn't be that hard)

I think the default recommendation could be something like "If you need to optimize your native non-Rust dependency with PGO - please create an issue in the upstream package to support PGO build mode". And in the Rust crates something_sys the maintainers could implement some build.rs PGO-related magic (if the real need exists).

I'm not sure how we should document this though. "If you have native code, cargo-pgo won't PGO optimize it?". I'm not sure if that adds any relevant value, as cargo-pgo doesn't promise anything about C/C++ PGO optimizations.

Hah, I also do not know how would be better to highlight (and should we at do it or not). But maybe for someone it would surprising to understand, that only Rust dependencies are optimized in the Rust projects, even if you (re)compile whole Rust project with cargo-pgo.

from cargo-pgo.