Code coverage and profiling don't work on non-X86_64 -musl targets because profiler_builtins isn't provided for them

[briansmith]

• Build dist-android with --enable-profiler #70054 added profiler_builtins for all Android targets
• Profile Guided Optimization (PGO) not working on aarch64 #57257 added support for the profiler builtins for x86_64-unknown-linux-gnu targets.
• build dist-aarch64-linux with --enable-profiler #60476 added the profiler builtins for aarch64-unknown-linux-gnu.

This indicates to me that it should be practical to enable the profiler feature for -musl targets on ARM and Intel targets, and we should do so. At a minimum, the following very common targets should have the profiler feature enabled:

• x86_64-unknown-linux-musl; done in Profile Guided Optimization (PGO) not working on aarch64 #57257
• aarch64-unknown-linux-musl; done in Enable sanitizers and profiler for aarch64-unknown-linux-musl #111575
• arm-unknown-linux-musleabihf
• armv7-unknown-linux-musleabihf
• i686-unknown-linux-musl

[kobehz]

• Build dist-android with --enable-profiler #70054 added profiler_builtins for all Android targets
• Profile Guided Optimization (PGO) not working on aarch64 #57257 added support for the profiler builtins for x86_64-unknown-linux-gnu targets.
• build dist-aarch64-linux with --enable-profiler #60476 added the profiler builtins for aarch64-unknown-linux-gnu.

This indicates to me that it should be practical to enable the profiler feature for -musl targets on ARM and Intel targets, and we should do so. At a minimum, the following very common targets should have the profiler feature enabled:

• x86_64-unknown-linux-musl; done in Profile Guided Optimization (PGO) not working on aarch64 #57257
• aarch64-unknown-linux-musl
• arm-unknown-linux-musleabihf
• armv7-unknown-linux-musleabihf
• i686-unknown-linux-musl

I have the same problem for target aarch64-unknown-linux-musl.
What time do you expect to enable the the profiler feature for these targets?
Or what can I do myself to solve the problem?

[briansmith]

Or what can I do myself to solve the problem?

I think there's not much stopping us from making a PR to rust-lang/rust that copies https://github.com/rust-lang/rust/pull/76035/files for the other musl targets.

[mati865]

This might be harder than it sounds since only x86_64 musl target is natively built. Others are cross compiled from Linux GNU target.
But trying to do what Brian said won't hurt.

[clarfonthey]

Ran into something similar to this after trying to test some code via cross. If I'm understanding correctly, all tier-2 and below targets don't have support for profiler_builtins. That includes not only the MUSL targets, but targets for architectures other than x86_64, aarch64, and i686.

[kobehz]

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[tmandry]

It definitely works for Fuchsia (Tier 2) since we use it there. But we also build our own toolchain. This is probably (at least in part) an issue with the way the official distribution for those targets is configured and built.

[briansmith]

This might be harder than it sounds since only x86_64 musl target is natively built. Others are cross compiled from Linux GNU target.

https://github.com/rust-lang/rust/pull/111575/files added profiler support by just adding --enable-profiler to ENV RUST_CONFIGURE_ARGS. So I think it isn't as hard as we're worried about.

[kobehz]

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[clarfonthey]

@kobehz You definitely have your GitHub notifications configured incorrectly. Please make sure that you're not auto-replying to notification emails.