LoongArch: Added Loongson ASX base instruction support.

gcc/ChangeLog:

	* config/loongarch/loongarch-modes.def
	(VECTOR_MODES): Added Loongson ASX instruction support.
	* config/loongarch/loongarch-protos.h (loongarch_split_256bit_move): Ditto.
	(loongarch_split_256bit_move_p): Ditto.
	(loongarch_expand_vector_group_init): Ditto.
	(loongarch_expand_vec_perm_1): Ditto.
	* config/loongarch/loongarch.cc (loongarch_symbol_insns): Ditto.
	(loongarch_valid_offset_p): Ditto.
	(loongarch_valid_index_p): Ditto.
	(loongarch_address_insns): Ditto.
	(loongarch_const_insns): Ditto.
	(loongarch_legitimize_move): Ditto.
	(loongarch_builtin_vectorization_cost): Ditto.
	(loongarch_split_move_p): Ditto.
	(loongarch_split_move): Ditto.
	(loongarch_output_move_index): Ditto.
	(loongarch_output_move_index_float): Ditto.
	(loongarch_split_256bit_move_p): Ditto.
	(loongarch_split_256bit_move): Ditto.
	(loongarch_output_move): Ditto.
	(loongarch_print_operand_reloc): Ditto.
	(loongarch_print_operand): Ditto.
	(loongarch_hard_regno_mode_ok_uncached): Ditto.
	(loongarch_hard_regno_nregs): Ditto.
	(loongarch_class_max_nregs): Ditto.
	(loongarch_can_change_mode_class): Ditto.
	(loongarch_mode_ok_for_mov_fmt_p): Ditto.
	(loongarch_vector_mode_supported_p): Ditto.
	(loongarch_preferred_simd_mode): Ditto.
	(loongarch_autovectorize_vector_modes): Ditto.
	(loongarch_lsx_output_division): Ditto.
	(loongarch_expand_lsx_shuffle): Ditto.
	(loongarch_expand_vec_perm): Ditto.
	(loongarch_expand_vec_perm_interleave): Ditto.
	(loongarch_try_expand_lsx_vshuf_const): Ditto.
	(loongarch_expand_vec_perm_even_odd_1): Ditto.
	(loongarch_expand_vec_perm_even_odd): Ditto.
	(loongarch_expand_vec_perm_1): Ditto.
	(loongarch_expand_vec_perm_const_1): Ditto.
	(loongarch_is_quad_duplicate): Ditto.
	(loongarch_is_double_duplicate): Ditto.
	(loongarch_is_odd_extraction): Ditto.
	(loongarch_is_even_extraction): Ditto.
	(loongarch_is_extraction_permutation): Ditto.
	(loongarch_is_center_extraction): Ditto.
	(loongarch_is_reversing_permutation): Ditto.
	(loongarch_is_di_misalign_extract): Ditto.
	(loongarch_is_si_misalign_extract): Ditto.
	(loongarch_is_lasx_lowpart_interleave): Ditto.
	(loongarch_is_lasx_lowpart_interleave_2): Ditto.
	(COMPARE_SELECTOR): Ditto.
	(loongarch_is_lasx_lowpart_extract): Ditto.
	(loongarch_is_lasx_highpart_interleave): Ditto.
	(loongarch_is_lasx_highpart_interleave_2): Ditto.
	(loongarch_is_elem_duplicate): Ditto.
	(loongarch_is_op_reverse_perm): Ditto.
	(loongarch_is_single_op_perm): Ditto.
	(loongarch_is_divisible_perm): Ditto.
	(loongarch_is_triple_stride_extract): Ditto.
	(loongarch_expand_vec_perm_const_2): Ditto.
	(loongarch_sched_reassociation_width): Ditto.
	(loongarch_expand_vector_extract): Ditto.
	(emit_reduc_half): Ditto.
	(loongarch_expand_vec_unpack): Ditto.
	(loongarch_expand_vector_group_init): Ditto.
	(loongarch_expand_vector_init): Ditto.
	(loongarch_expand_lsx_cmp): Ditto.
	(loongarch_builtin_support_vector_misalignment): Ditto.
	* config/loongarch/loongarch.h (UNITS_PER_LASX_REG): Ditto.
	(BITS_PER_LASX_REG): Ditto.
	(STRUCTURE_SIZE_BOUNDARY): Ditto.
	(LASX_REG_FIRST): Ditto.
	(LASX_REG_LAST): Ditto.
	(LASX_REG_NUM): Ditto.
	(LASX_REG_P): Ditto.
	(LASX_REG_RTX_P): Ditto.
	(LASX_SUPPORTED_MODE_P): Ditto.
	* config/loongarch/loongarch.md: Ditto.
	* config/loongarch/lasx.md: New file.