* internal-fn.def (GOACC_REDUCTION): New.

	* internal-fn.def (GOACC_REDUCTION): New.
	* internal-fn.h (enum ifn_goacc_reduction_kind): New.
	* internal-fn.c (expand_GOACC_REDUCTION): New.
	* target.def (goacc.reduction): New OpenACC hook.
	* targhooks.h (default_goacc_reduction): Declare.
	* doc/tm.texi.in: Add TARGET_GOACC_REDUCTION.
	* doc/tm.texi: Rebuilt.
	* omp-low.c (oacc_get_reduction_array_id, oacc_max_threads,
	scan_sharing_clauses): Remove oacc reduction handling here.
	(lower_rec_input_clauses): Don't handle OpenACC reductions here.
	(oacc_lower_reduction_var_helper): Delete.
	(lower_oacc_reductions): New.
	(lower_reduction_clauses): Don't handle OpenACC reductions here.
	(lower_oacc_head_tail): Call lower_oacc_reductions.
	(oacc_gimple_assign, oacc_init_reduction_array,
	oacc_initialize_reduction_data, oacc_finalize_reduction_data,
	oacc_process_reduction_data): Delete.
	(lower_omp_target): Remove old OpenACC reduction handling.  Insert
	dummy OpenACC gang reduction for reductions at outer level.
	(oacc_loop_xform_head_tail): Transform IFN_GOACC_REDUCTION.
	(default_goacc_reduction): New.
	(execute_oacc_device_lower): Handle IFN_GOACC_REDUCTION.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@229767 138bc75d-0d04-0410-961f-82ee72b054a4