Improve IPA-CP handling of self-recursive calls

Improve IPA-CP handling of self-recursive calls

2018-04-11  Martin Jambor  <mjambor@suse.cz>

	PR ipa/84149
	* ipa-cp.c (propagate_vals_across_pass_through): Expand comment.
	(cgraph_edge_brings_value_p): New parameter dest_val, check if it is
	not the same as the source val.
	(cgraph_edge_brings_value_p): New parameter.
	(gather_edges_for_value): Pass destination value to
	cgraph_edge_brings_value_p.
	(perhaps_add_new_callers): Likewise.
	(get_info_about_necessary_edges): Likewise and exclude values brought
	only by self-recursive edges.
	(create_specialized_node): Redirect only clones of self-calling edges.
	(+self_recursive_pass_through_p): New function.
	(find_more_scalar_values_for_callers_subset): Use it.
	(find_aggregate_values_for_callers_subset): Likewise.
	(known_aggs_to_agg_replacement_list): Removed.
	(decide_whether_version_node): Re-calculate known constants for all
	remaining context clones.

From-SVN: r259319