I've improved the following implementation of memcpy:
"sysdeps/i386/i686/multiarch/memcpy-ssse3.S".
The patch includes some minor style fixes, but the important part is
just using prefetch loops for the case:
DATA_CACHE_SIZE_HALF <= len < SHARED_CACHE_SIZE_HALF and
src and dst pointers have unequal 16 byte alignments.
This gives from 6% - 50% performance boost on the atom machine, about
24,73% in geometric mean.
