2012-06-19 Tom de Vries <vries@codesourcery.com>

	    Maxim Kuvyrkov  <maxim@codesourcery.com>

	* config/mips/mips.c (mips_emit_pre_atomic_barrier_p,)
	(mips_emit_post_atomic_barrier_p): New static functions.
	(mips_process_sync_loop): Use them.  Emit sync memory barriers in
	accordance with memory model semantics.  Add return of CMP result for
	compare_and_swap.
	* config/mips/mips.md: Update comment.
	(sync_cmp): New attribute.
	(sync_memmodel): New attribute replacing sync_release_barrier.
	* config/mips/sync.md (UNSPEC_ATOMIC_COMPARE_AND_SWAP,)
	(UNSPEC_ATOMIC_EXCHANGE, UNSPEC_ATOMIC_FETCH_OP): New constants.
	(sync_lock_test_and_set, test_and_set_12): Update.
	(atomic_compare_and_swap, atomic_exchange, atomic_exchange_llsc,)
	(atomic_fetch_add, atomic_fetch_add_llsc): New patterns.

Co-Authored-By: Maxim Kuvyrkov <maxim@codesourcery.com>

From-SVN: r188803