* config/aarch64/aarch64-protos.h

	* config/aarch64/aarch64-protos.h
	(aarch64_gen_atomic_cas): Declare.
	* config/aarch64/aarch64.c (aarch64_expand_compare_and_swap):
	Choose appropriate instruction pattern for the target.
	(aarch64_gen_atomic_cas): New.
	* config/aarch64/atomics.md (UNSPECV_ATOMIC_CAS): New.
	(atomic_compare_and_swap<mode>_1): Rename to
	aarch64_compare_and_swap<mode>.  Fix some indentation.
	(aarch64_compare_and_swap<mode>_lse): New.
	(aarch64_atomic_cas<mode>): New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@226858 138bc75d-0d04-0410-961f-82ee72b054a4