2017-07-20  Richard Biener  <rguenther@suse.de>

	* gimple.h (gimple_phi_result): Add gphi * overload.
	(gimple_phi_result_ptr): Likewise.
	(gimple_phi_arg): Likewise.  Adjust index assert to only
	allow actual argument accesses rather than all slots available
	by capacity.
	(gimple_phi_arg_def): Add gphi * overload.
	* tree-phinodes.c (make_phi_node): Initialize only actual
	arguments.
	(resize_phi_node): Clear memory not covered by old node,
	do not initialize excess argument slots.
	(reserve_phi_args_for_new_edge): Initialize new argument slot
	completely.

From-SVN: r250385