ports/133175: [patch] x11/pixman: enable SSE2 support autodetection

[bf]

The following reply was made to PR ports/133175; it has been noted by GNATS.

From: bf <bf2006a at yahoo.com>
To: bug-followup at FreeBSD.org
Cc: Anonymous <swell.k at gmail.com>
Subject: Re: ports/133175: [patch] x11/pixman: enable SSE2 support autodetection
Date: Sun, 29 Mar 2009 01:23:07 -0700 (PDT)

 Have you thought about the consequences for those architectures,
 like i386, that include machines with _and_ without these
 features?
 
 Right now, we don't distinguish between binary packages with
 and without SIMD in Ports, so many ports have such switches
 disabled, because binary packages built on one machine should
 be usable on another with the same architecture and OS version.
 
 Changes of this kind could break binary packages built,
 for example, by the FreeBSD package-building cluster, when used
 on older machines.  You may be able to enable _some_ SIMD
 support on architectures for which _every_ machine
 supports the SIMD instructions in question, but _only_
 on those architectures.  Otherwise you need to make bigger
 changes to the Ports infrastructure.  And in fact, some of
 these checks should be updated to disable SSE2, SSE3, etc.
 by default.
 
 Regards,
            b.