* gimple-pretty-print.c (dump_gimple_omp_atomic_load): Dump needed.
	(dump_gimple_omp_atomic_store): Likewise.
	* optabs.c (can_atomic_exchange_p): New.
	* optabs.h (can_atomic_exchange_p): Declare.
	* omp-low.c (expand_omp_atomic_load): Implement.
	(expand_omp_atomic_store): Likewise.
	(expand_omp_atomic): Update for new arguments to load/store.

From-SVN: r181296