[Bug 246194] math/blis: pacify portlint, add test target, optimize for power9

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=246194

--- Comment #2 from Piotr Kubaj <pkubaj at FreeBSD.org> ---
FreeBSD supports all IBM POWER chips from the first PPC970 (in Macs G5) up to
the latest POWER9 and also Freescale's ppc64 chips found in embedded devices.

So yes, optimizing for POWER9 will make it more useful to POWER9 users. It will
also make this port useless on all earlier generations, but:
1) since nothing depends on this port, optimizing to POWER9 will only be
relevant to people directly using this port on powerpc64 older than POWER9, not
to someone using some reverse dependency (because there are none),
2) I think people using software strictly for scientific computations tend to
use the latest available hardware because of power usage improvements. I don't
think anyone will use their old PowerMac G5 with this port.

Regarding complicating this port, on e.g. ARM we build generic binaries, but
per https://github.com/flame/blis/blob/master/config_registry, there are two
armv7-optimized variants and three aarch64-optimized variants, depending on the
actual CPU. For amd64, there are overall 11 possible variants (optimized for
specific CPUs).

This is why I proposed this port getting flavours, that would make it possible
for users to install their preferred version.

If you ask about POWER and BGQ in the above link, AFAIK this is IBM Blue Gene
which uses custom PowerPC chips and support for it is not available in FreeBSD
anyway.

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