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

[Kok, Auke]

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?


Auke