[Lunar-commits] r25168 - moonbase/trunk/graphics/libpng

[Jannis Pohlmann]

Am Tue, 17 Jul 2007 22:14:52 -0700
schrieb "Kok, Auke" <sofar at foo-projects.org>:

> Zbigniew Luszpinski wrote:
> > Author: zbiggy
> > Date: 2007-07-18 03:32:46 +0200 (Wed, 18 Jul 2007)
> > New Revision: 25168
> > 
> > Added:
> >    moonbase/trunk/graphics/libpng/BUILD
> > Log:
> > Bugfix: now libpng is compiled with low level MMX assembly
> > optimization when MMX ready CPU is detected during compilation.
> > This built-in asm optimization is faster than general CFLAGS.
> > libpng MMX check is a little bit crazy and _turns off_ building MMX
> > code when:
> > - march is higher than i686 (because it autoenables supported by
> > CPU simd optimizations)
> > - mmx,sse,3dnow are enabled manually using -m parameter or -mfpmath=
> > If MMX optimization is turned off you'll see PNG_NO_MMX_CODE flag
> > in compilation log several times. This bugfix fixes this problem by
> > temporary turning off bad flags and by providing alternative
> > optimization. libpng built with this bugfix returns: checking if
> > assembler code in pnggccrd.c can be compiled without
> > PNG_NO_MMX_CODE... yes in configure stage. In compilation log you
> > will not see PNG_NO_MMX_CODE anymore.
> > 
> > 
> > Added: moonbase/trunk/graphics/libpng/BUILD
> > ===================================================================
> > ---
> > moonbase/trunk/graphics/libpng/BUILD
> > (rev 0) +++ moonbase/trunk/graphics/libpng/BUILD	2007-07-18
> > 01:32:46 UTC (rev 25168) @@ -0,0 +1,12 @@ +(
> > +
> > +CFLAGS="${CFLAGS//march/mtune}"
> > +CFLAGS="${CFLAGS//=sse/=387}"
> > +CFLAGS="${CFLAGS//=387,387/=387}"
> > +CFLAGS="${CFLAGS//-mmmx/-mno-mmx}"
> > +CFLAGS="${CFLAGS//-m3dnow/-mno-3dnow}"
> > +CFLAGS="${CFLAGS//-msse/-mno-sse}"
> > +CFLAGS="-march=`uname -m` $CFLAGS"
> > +default_build
> 
> really, this kind of optimization is silly. did you measure the
> performance difference? How much is the average user going to benefit
> from this?

Optimizations just don't belong into the BUILD file, do they? Everyone
should be free to decide when to use them or not. That's why we have
the optimizations plugin for 'lunar'.

  - Jannis