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Increase alignment of av_malloc() as needed by AVX ASM.

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Signed-off-by: Reinhard Tartler <siretart@tauware.de>
This commit is contained in:
Vitor Sessak 2011-04-23 19:24:31 +02:00 committed by Reinhard Tartler
parent 33cbfa6fa3
commit 13dfce3d44
1 changed files with 7 additions and 9 deletions
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16
libavutil/mem.c
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@ -69,21 +69,21 @@ void *av_malloc(size_t size)
#endif
/* let's disallow possible ambiguous cases */
if(size > (INT_MAX-16) )
if(size > (INT_MAX-32) )
return NULL;
#if CONFIG_MEMALIGN_HACK
ptr = malloc(size+16);
ptr = malloc(size+32);
if(!ptr)
return ptr;
diff= ((-(long)ptr - 1)&15) + 1;
diff= ((-(long)ptr - 1)&31) + 1;
ptr = (char*)ptr + diff;
((char*)ptr)[-1]= diff;
#elif HAVE_POSIX_MEMALIGN
if (posix_memalign(&ptr,16,size))
if (posix_memalign(&ptr,32,size))
ptr = NULL;
#elif HAVE_MEMALIGN
ptr = memalign(16,size);
ptr = memalign(32,size);
/* Why 64?
Indeed, we should align it:
on 4 for 386
@ -93,10 +93,8 @@ void *av_malloc(size_t size)
Because L1 and L2 caches are aligned on those values.
But I don't want to code such logic here!
*/
/* Why 16?
Because some CPUs need alignment, for example SSE2 on P4, & most RISC CPUs
it will just trigger an exception and the unaligned load will be done in the
exception handler or it will just segfault (SSE2 on P4).
/* Why 32?
For AVX ASM. SSE / NEON needs only 16.
Why not larger? Because I did not see a difference in benchmarks ...
*/
/* benchmarks with P3