emit-rtl.c (need_atomic_barrier_p): New function.

	* emit-rtl.c (need_atomic_barrier_p): New function.
	* emit-rtl.h (need_atomic_barrier_p): Declare it.
	* config/alpha/alpha.c (alpha_{pre,post}_atomic_barrier): Use it.
	* config/arm/arm.c (arm_{pre,post}_atomic_barrier): Use it.
	* config/tilegx/tilegx.c (tile_{pre,post}_atomic_barrier): Use it.
	* config/mips/mips.c (mips_{pre,post}_atomic_barrier_p): Remove.
	(mips_process_sync_loop): Use generic version instead.

From-SVN: r188806