[AArch64] Use atomic instructions for swap and fetch-update operations.

[AArch64] Use atomic instructions for swap and fetch-update operations.

gcc/
2015-09-22  Matthew Wahab  <matthew.wahab@arm.com>

	* config/aarch64/aarch64-protos.h (aarch64_gen_atomic_ldop):
	Declare.
	* config/aarch64/aarch64.c (aarch64_emit_atomic_swap): New.
	(aarch64_gen_atomic_ldop): New.
	(aarch64_split_atomic_op): Fix whitespace and add a comment.
	* config/aarch64/atomics.md (UNSPECV_ATOMIC_SWP): New.
	(aarch64_compare_and_swap<mode>_lse): Fix some whitespace.
	(atomic_exchange<mode>): Replace with an expander.
	(aarch64_atomic_exchange<mode>): New.
	(aarch64_atomic_exchange<mode>_lse): New.
	(aarch64_atomic_<atomic_optab><mode>): Fix some whitespace.
	(aarch64_atomic_swp<mode>): New.

gcc/testsuite/
2015-09-22  Matthew Wahab  <matthew.wahab@arm.com>

	* gcc.target/aarch64/atomic-inst-ops.inc: (TEST_MODEL): New.
	(TEST_ONE): New.
        * gcc.target/aarch64/atomic-inst-swap.c: New.

From-SVN: r227998