Now that the IFUNC infrastructure for aarch64 is in place, here is a
patch to use it to create ThunderX specific versions of memcpy and
memmove.

This was part of my original patch before it was split in two and a
couple of issues were raised at that time. 

Siddhesh Poyarekar wanted to separate the generic and thunderx copies
of memcpy/memmove instead of using ifdefs in a combined source file.
I prefer the ifdef version as a cleaner implementation with less code
duplication but I can change it if that is the consensus.

Also Adhemerval Zanella did some benchmarking that showed the
prefetching done in the thunderx version might be appropriate for the
generic version.  However if you look at the prefetching we only do it
every other time through the loop.  This is because the loop copies 64
bytes and the ThunderX cache line size is 128 bytes.  If other aarch64
chips have a 64 byte cache line they might want a different prefetching
setup.

If people think we should use the ThunderX version of memcpy for all
aarch64 systems I am happy to drop this patch and create one that just
changes memcpy.S to do the ThunderX style prefetches for all aarch64
systems.

Steve Ellcey
sellcey@cavium.com


2017-03-24  Steve Ellcey  <sellcey@caviumnetworks.com>

	* sysdeps/aarch64/memcpy.S (MEMMOVE, MEMCPY): New macros.
	(memmove): Use MEMMOVE for name.
	(memcpy): Use MEMCPY for name.  Add loop with prefetching
	under USE_THUNDERX macro.
	* sysdeps/aarch64/multiarch/Makefile: New file.
	* sysdeps/aarch64/multiarch/ifunc-impl-list.c: Likewise.
	* sysdeps/aarch64/multiarch/init-arch.h: Likewise.
	* sysdeps/aarch64/multiarch/memcpy.c: Likewise.
	* sysdeps/aarch64/multiarch/memcpy_generic.S: Likewise.
	* sysdeps/aarch64/multiarch/memcpy_thunderx.S: Likewise.
	* sysdeps/aarch64/multiarch/memmove.c: Likewise.