Make function.c use function_arg_info internally

Make function.c use function_arg_info internally

This patch adds a function_arg_info field to assign_parm_data_one,
so that:

  - passed_type -> arg.type
  - promoted_mode -> arg.mode
  - named_arg -> arg.named

We can then pass this function_arg_info directly to the converted
hooks.

Between the initialisation of the assign_parm_data_one and the
application of promotion rules (which is a state internal to
assign_parm_find_data_types), arg.mode is equivalent to passed_mode
(i.e. to TYPE_MODE).

2019-08-20  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* function.c (assign_parm_data_one): Replace passed_type,
	promoted_mode and named_arg with a function_arg_info field.
	(assign_parm_find_data_types): Remove local variables and
	assign directly to "data".  Make data->passed_mode shadow
	data->arg.mode until promotion, then assign the promoted
	mode to data->arg.mode.
	(assign_parms_setup_varargs, assign_parm_find_entry_rtl)
	(assign_parm_find_stack_rtl, assign_parm_adjust_entry_rtl)
	(assign_parm_remove_parallels, assign_parm_setup_block_p)
	(assign_parm_setup_block, assign_parm_setup_reg)
	(assign_parm_setup_stack, assign_parms, gimplify_parameters): Use
	arg.mode instead of promoted_mode, arg.type instead of passed_type
	and arg.named instead of named_arg.  Use data->arg for
	function_arg_info structures that had the field values passed_type,
	promoted_mode and named_arg.  Base other function_arg_infos on
	data->arg, changing the necessary properties.

From-SVN: r274705