Make more use of REG_NREGS

Make more use of REG_NREGS

An upcoming patch will convert hard_regno_nregs into an inline
function, which in turn allows hard_regno_nregs to be used as the
name of a targetm field.  This patch rewrites uses that are more
easily (and efficiently) written as REG_NREGS.

2017-09-12  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* caller-save.c (add_used_regs): Use REG_NREGS instead of
	hard_regno_nregs.
	* config/aarch64/aarch64.c (aarch64_split_combinev16qi): Likewise.
	* config/arm/arm.c (output_move_neon): Likewise.
	(arm_attr_length_move_neon): Likewise.
	(neon_split_vcombine): Likewise.
	* config/c6x/c6x.c (c6x_mark_reg_read): Likewise.
	(c6x_mark_reg_written): Likewise.
	(c6x_dwarf_register_span): Likewise.
	* config/i386/i386.c (ix86_save_reg): Likewise.
	* config/ia64/ia64.c (mark_reg_gr_used_mask): Likewise.
	(rws_access_reg): Likewise.
	* config/s390/s390.c (s390_call_saved_register_used): Likewise.
	* mode-switching.c (create_pre_exit): Likewise.
	* ree.c (combine_reaching_defs): Likewise.
	(add_removable_extension): Likewise.
	* regcprop.c (find_oldest_value_reg): Likewise.
	(copyprop_hardreg_forward_1): Likewise.
	* reload.c (reload_inner_reg_of_subreg): Likewise.
	(push_reload): Likewise.
	(combine_reloads): Likewise.
	(find_dummy_reload): Likewise.
	(reload_adjust_reg_for_mode): Likewise.
	* reload1.c (find_reload_regs): Likewise.
	(forget_old_reloads_1): Likewise.
	(reload_reg_free_for_value_p): Likewise.
	(reload_adjust_reg_for_temp): Likewise.
	(emit_reload_insns): Likewise.
	(delete_output_reload): Likewise.
	* sel-sched.c (choose_best_reg_1): Likewise.
	(choose_best_pseudo_reg): Likewise.

From-SVN: r252010