Re: Ryzen PPA znver1 optimizations

[Jonathan Wakely <jwakely.gcc@gmail.com>]

On Fri, 8 Mar 2019 at 22:00, Vanida Plamondon
<vanida.plamondon@gmail.com> wrote:
>
> OK, so it seems I need to give more information to clarify what I am
> trying to do.
>
> I am not invoking or configuring gcc directly.

(If you're creating a toolchain then surely you're configuring GCC.)

> I am creating debian
> source code packages which are then dispatched to launchpad.net, which
> then automatically compiles and builds my package based on the debian
> configuration files. I am trying to created a toolchain that does this
> automatically while also setting the znver1 optimisations
> automatically.
>
> As far as I can tell, the --with-arch= and --with-cpu= gcc
> configuration options set defaults, and do not enforce compilation
> with these options if a package specifically configures a different
> cpu or architecture, so correct me if I am wrong.

If by "configures a different cpu or architecture" you mean "uses the
-march option when invoking GCC" then you're correct.

Using --with-arch=znver1 will make GCC automatically select that
architecture. But it won't prevent that automatic selection being
overridden by an explicit -march option.


> Regardless, I do
> have those options set in the various versions of gcc in my toolchain,
> but I need gcc to ignore rogue packages that configure to a different
> x86 architecture. My PPAs only target znver1 for x86 code, so nothing
> breaks if my toolchain ignores other x86 architectures.
>
> Since I am trying to create an automatic toolchain, it would be much
> easier to have a gcc that ignores non-default x86 configuration
> options then it is to try to create a script that finds, catches, and
> corrects an upstream package that uses a non-default configuration.

Yes, that does seem simpler.

> If the --with-arch= and --with-cpu= gcc configuration options cause
> gcc to ignore non-default configure options, then please, let me know.

I find this use of "configure options" confusing too. You're talking
about flags passed to GCC when invoking it, not "configure options",
right?