[AArch64] Implement movmem for the benefit of inline memcpy
gcc/
* config/aarch64/aarch64-protos.h (aarch64_expand_movmem): New.
* config/aarch64/aarch64.c (aarch64_move_pointer): New.
(aarch64_progress_pointer): Likewise.
(aarch64_copy_one_part_and_move_pointers): Likewise.
(aarch64_expand_movmen): Likewise.
* config/aarch64/aarch64.h (MOVE_RATIO): Set low.
* config/aarch64/aarch64.md (movmem<mode>): New.
gcc/testsuite/
* gcc.dg/tree-ssa/pr42585.c: Skip for AArch64.
* gcc.dg/tree-ssa/sra-12.c: Likewise.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@211314 138bc75d-0d04-0410-961f-82ee72b054a4