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buffer_is_zero: use vector optimizations if possible 

performance gain on SSE2 is approx. 20-25%. altivec
is not tested. performance for unsigned long arithmetic
is unchanged.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Orit Wasserman <owasserm@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Peter Lieven 2013-03-26 10:58:33 +01:00 committed by Juan Quintela
parent 41a259bd2b
commit 56ded708ec
1 changed files with 5 additions and 0 deletions
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5
util/cutils.c
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@ -215,6 +215,11 @@ bool buffer_is_zero(const void *buf, size_t len)
long d0, d1, d2, d3; long d0, d1, d2, d3;
const long * const data = buf; const long * const data = buf;
/* use vector optimized zero check if possible */
if (can_use_buffer_find_nonzero_offset(buf, len)) {
return buffer_find_nonzero_offset(buf, len) == len;
}
assert(len % (4 * sizeof(long)) == 0); assert(len % (4 * sizeof(long)) == 0);
len /= sizeof(long); len /= sizeof(long);