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Re: jpeg-turbo 6.2 and ppc G3



On Tue, Jul 05, 2016 at 07:46:10PM +0200, Riccardo Mottola wrote:
> Hi Lennart,
> 
> Lennart Sorensen wrote:
> >On Sat, Jul 02, 2016 at 08:57:56AM +0200, Riccardo Mottola wrote:
> >>I what test program could I use? I noticed that e.g. Firefox (which works)
> >>is not linked against it.
> >You could try forcing altivec off in libjpegturbo by setting the environment:
> >
> >export JSIMD_FORCENONE=1
> 
> that works! Once set, the application loads several JPG files without
> issues.

So it turns out libjpeg-turbo has NO runtime detection on powerpc and
just assumes altivec is valid.

This untested patch might work:

--- simd/jsimd_powerpc.c.orig   2016-07-05 14:57:48.305763762 -0400
+++ simd/jsimd_powerpc.c        2016-07-05 14:58:04.453763762 -0400
@@ -32,7 +32,10 @@
   if (simd_support != ~0U)
     return;
 
-  simd_support = JSIMD_ALTIVEC;
+  if (__builtin_cpu_supports("altivec"))
+    simd_support = JSIMD_ALTIVEC;
+  else
+    simd_support = 0;
 
   /* Force different settings through environment variables */
   env = getenv("JSIMD_FORCENONE");

-- 
Len Sorensen


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