rust CFLAGS

Message

paluszak · Post by **paluszak** » Wed Feb 13, 2019 2:12 pm

Hi,

Is there a way to add CPU-specific flags for rust ebuilds to make.conf? For instance something along the lines '-C target-cpu=native' to generate CPU optimized code? Or possibly other codegen options (https://doc.rust-lang.org/rustc/codegen ... index.html)?

J.

Post by **NeddySeagoon** » Wed Feb 13, 2019 7:31 pm

paluszak,

Yes and no.

Yes you can have per package CFLAGS. No, you don't do it in make.conf.

The process is documented in Per-package environment variables
The worked example is for debugging but you will be able to adapt it.

-- edit --

EXTRA_ECONF= lets you pass additional options to some build systems.
This may be useful too.

paluszak · Post by **paluszak** » Wed Feb 13, 2019 7:41 pm

I know how to set up per-package CFLAGS, but what I'm asking about is if there's an equivalent of CFLAGS for rust packages. For istance, I'd like my rust packages to be built with '-C target-cpu=native' option added to command line.

Post by **NeddySeagoon** » Wed Feb 13, 2019 8:41 pm

paluszak,

Sorry, I misunderstood your question. I can delete my posts and your response to get your opening post back into the unanswered post search if you like.

paluszak · Post by **paluszak** » Wed Feb 13, 2019 8:59 pm

No, that's fine. I'll try to delve into the rust eclass. For now I found only that setting RUSTFLAGS env value adds given options to cargo builds, but that's what I found in the cargo man page. So it's kind of solved, but only kind of - afaik you can use rustc directly and not exclusively via cargo build system.

Ant P. · Post by **Ant P.** » Sat Mar 30, 2019 7:58 am

Putting RUSTFLAGS="-C target-cpu=native" into make.conf seems to have an effect - tested by putting an invalid option in there and watching emerge fail.

Unlike CFLAGS it's probably safe to use native there for the foreseeable future because rust has no distcc support.

Post by **NeddySeagoon** » Sat Mar 30, 2019 10:47 am

Ant P.

For a long time now using -march=native in CFLAGS has been 'safe' with distcc.
distcc won't distribute when it sees that.
You no longer gent a mix of arches back, depending on what built on what arch.

paluszak · Post by **paluszak** » Sat Mar 30, 2019 10:51 am

Ant P. wrote:Putting RUSTFLAGS="-C target-cpu=native" into make.conf seems to have an effect - tested by putting an invalid option in there and watching emerge fail.

Unlike CFLAGS it's probably safe to use native there for the foreseeable future because rust has no distcc support.

Yep, I noticed that. Seems to work perfectly fine. There are some build that fail with lto, mostly those linking against external C code, like Firefox.

rust CFLAGS

rust CFLAGS

[SOLVED] rust CFLAGS