arm: Make use of RTL predicates

2020-11-13  Andrea Corallo  <andrea.corallo@arm.com>

	* config/arm/aarch-common.c (aarch_accumulator_forwarding): Use
	RTL predicates where possible.
	* config/arm/arm.c (legitimate_pic_operand_p)
	(legitimize_pic_address, arm_is_segment_info_known)
	(can_avoid_literal_pool_for_label_p)
	(thumb1_legitimate_address_p, arm_legitimize_address)
	(arm_tls_referenced_p, thumb_legitimate_constant_p)
	(REG_OR_SUBREG_REG, thumb1_rtx_costs, thumb1_size_rtx_costs)
	(arm_adjust_cost, arm_coproc_mem_operand_wb)
	(neon_vector_mem_operand, neon_struct_mem_operand)
	(symbol_mentioned_p, label_mentioned_p, )
	(load_multiple_sequence, store_multiple_sequence)
	(arm_select_cc_mode, arm_reload_in_hi, arm_reload_out_hi)
	(mem_ok_for_ldrd_strd, arm_emit_call_insn, output_move_neon)
	(arm_attr_length_move_neon, arm_assemble_integer)
	(arm_emit_coreregs_64bit_shift, arm_valid_symbolic_address_p)
	(extract_base_offset_in_addr, fusion_load_store): Likewise.