Subject: Re: [PATCH v2 5/5] gnu: Add wfmash.

From: Maxime Devos <[email-masked]>
Date: Thu, 31 Mar 2022 15:07:49 +0200

Efraim Flashner schreef op do 31-03-2022 om 15:18 [+0300]:
> > Arun Isaac schreef op do 31-03-2022 om 12:58 [+0530]:
> > > +                       (("-march=native") ""))
> > 
> > This is also wrong for x86 systems because it makes the build non-
> > reproducible.  Also, has upstream been informed about some of the
> > compiler flags being architecture-specific?
> 
> I'm pretty sure upstream is aware of it, and the -mcx16 flag. That
> whole phase doesn't need to be non-x86_64 only, upstream prefers it
> that way to get fater results

wfmash could be written to detect CPU features at runtime and there is
also --tune.  Also, upstream preferring march=native does not make the
build reproducible.

> but IMO it would be fine to move it into a snippet.

It does not have to be in a snippet, it just needs to be reproducible
(so no march=native, whether on x86 or not).

Upstream seems to be aware of the non-x86
(https://github.com/ekg/wfmash/issues/125) but they do not seem to be
aware of the problems with march=native.

Greetings,
Maxime