LoongArch: Simplify {lsx_,lasx_x}v{add,sub,mul}l{ev,od} description

These pattern definitions are tediously long, invoking 32 UNSPECs and
many hard-coded long const vectors.  To simplify them, at first we use
the TImode vector operations instead of the UNSPECs, then we adopt an
approach in AArch64: using a special predicate to match the const
vectors for odd/even indices for define_insn's, and generate those
vectors in define_expand's.

For "backward compatibilty" we need to provide a "punned" version for
the operations invoking TImode vectors as the intrinsics still expect
DImode vectors.

The stat is "201 insertions, 905 deletions."

gcc/ChangeLog:

	* config/loongarch/lasx.md (UNSPEC_LASX_XVADDWEV): Remove.
	(UNSPEC_LASX_XVADDWEV2): Remove.
	(UNSPEC_LASX_XVADDWEV3): Remove.
	(UNSPEC_LASX_XVSUBWEV): Remove.
	(UNSPEC_LASX_XVSUBWEV2): Remove.
	(UNSPEC_LASX_XVMULWEV): Remove.
	(UNSPEC_LASX_XVMULWEV2): Remove.
	(UNSPEC_LASX_XVMULWEV3): Remove.
	(UNSPEC_LASX_XVADDWOD): Remove.
	(UNSPEC_LASX_XVADDWOD2): Remove.
	(UNSPEC_LASX_XVADDWOD3): Remove.
	(UNSPEC_LASX_XVSUBWOD): Remove.
	(UNSPEC_LASX_XVSUBWOD2): Remove.
	(UNSPEC_LASX_XVMULWOD): Remove.
	(UNSPEC_LASX_XVMULWOD2): Remove.
	(UNSPEC_LASX_XVMULWOD3): Remove.
	(lasx_xv<addsubmul:optab>wev_h_b<u>): Remove.
	(lasx_xv<addsubmul:optab>wev_w_h<u>): Remove.
	(lasx_xv<addsubmul:optab>wev_d_w<u>): Remove.
	(lasx_xvaddwev_q_d): Remove.
	(lasx_xvsubwev_q_d): Remove.
	(lasx_xvmulwev_q_d): Remove.
	(lasx_xv<addsubmul:optab>wod_h_b<u>): Remove.
	(lasx_xv<addsubmul:optab>wod_w_h<u>): Remove.
	(lasx_xv<addsubmul:optab>wod_d_w<u>): Remove.
	(lasx_xvaddwod_q_d): Remove.
	(lasx_xvsubwod_q_d): Remove.
	(lasx_xvmulwod_q_d): Remove.
	(lasx_xvaddwev_q_du): Remove.
	(lasx_xvsubwev_q_du): Remove.
	(lasx_xvmulwev_q_du): Remove.
	(lasx_xvaddwod_q_du): Remove.
	(lasx_xvsubwod_q_du): Remove.
	(lasx_xvmulwod_q_du): Remove.
	(lasx_xv<addmul:optab>wev_h_bu_b): Remove.
	(lasx_xv<addmul:optab>wev_w_hu_h): Remove.
	(lasx_xv<addmul:optab>wev_d_wu_w): Remove.
	(lasx_xv<addmul:optab>wod_h_bu_b): Remove.
	(lasx_xv<addmul:optab>wod_w_hu_h): Remove.
	(lasx_xv<addmul:optab>wod_d_wu_w): Remove.
	(lasx_xvaddwev_q_du_d): Remove.
	(lasx_xvsubwev_q_du_d): Remove.
	(lasx_xvmulwev_q_du_d): Remove.
	(lasx_xvaddwod_q_du_d): Remove.
	(lasx_xvsubwod_q_du_d): Remove.
	* config/loongarch/lsx.md (UNSPEC_LSX_XVADDWEV): Remove.
	(UNSPEC_LSX_VADDWEV2): Remove.
	(UNSPEC_LSX_VADDWEV3): Remove.
	(UNSPEC_LSX_VSUBWEV): Remove.
	(UNSPEC_LSX_VSUBWEV2): Remove.
	(UNSPEC_LSX_VMULWEV): Remove.
	(UNSPEC_LSX_VMULWEV2): Remove.
	(UNSPEC_LSX_VMULWEV3): Remove.
	(UNSPEC_LSX_VADDWOD): Remove.
	(UNSPEC_LSX_VADDWOD2): Remove.
	(UNSPEC_LSX_VADDWOD3): Remove.
	(UNSPEC_LSX_VSUBWOD): Remove.
	(UNSPEC_LSX_VSUBWOD2): Remove.
	(UNSPEC_LSX_VMULWOD): Remove.
	(UNSPEC_LSX_VMULWOD2): Remove.
	(UNSPEC_LSX_VMULWOD3): Remove.
	(lsx_v<addsubmul:optab>wev_h_b<u>): Remove.
	(lsx_v<addsubmul:optab>wev_w_h<u>): Remove.
	(lsx_v<addsubmul:optab>wev_d_w<u>): Remove.
	(lsx_vaddwev_q_d): Remove.
	(lsx_vsubwev_q_d): Remove.
	(lsx_vmulwev_q_d): Remove.
	(lsx_v<addsubmul:optab>wod_h_b<u>): Remove.
	(lsx_v<addsubmul:optab>wod_w_h<u>): Remove.
	(lsx_v<addsubmul:optab>wod_d_w<u>): Remove.
	(lsx_vaddwod_q_d): Remove.
	(lsx_vsubwod_q_d): Remove.
	(lsx_vmulwod_q_d): Remove.
	(lsx_vaddwev_q_du): Remove.
	(lsx_vsubwev_q_du): Remove.
	(lsx_vmulwev_q_du): Remove.
	(lsx_vaddwod_q_du): Remove.
	(lsx_vsubwod_q_du): Remove.
	(lsx_vmulwod_q_du): Remove.
	(lsx_v<addmul:optab>wev_h_bu_b): Remove.
	(lsx_v<addmul:optab>wev_w_hu_h): Remove.
	(lsx_v<addmul:optab>wev_d_wu_w): Remove.
	(lsx_v<addmul:optab>wod_h_bu_b): Remove.
	(lsx_v<addmul:optab>wod_w_hu_h): Remove.
	(lsx_v<addmul:optab>wod_d_wu_w): Remove.
	(lsx_vaddwev_q_du_d): Remove.
	(lsx_vsubwev_q_du_d): Remove.
	(lsx_vmulwev_q_du_d): Remove.
	(lsx_vaddwod_q_du_d): Remove.
	(lsx_vsubwod_q_du_d): Remove.
	(lsx_vmulwod_q_du_d): Remove.
	* config/loongarch/loongarch-modes.def: Add V4TI and V1DI.
	* config/loongarch/loongarch-protos.h
	(loongarch_gen_stepped_int_parallel): New function prototype.
	* config/loongarch/loongarch.cc (loongarch_print_operand):
	Accept 'O' for printing "ev" or "od."
	(loongarch_gen_stepped_int_parallel): Implement.
	* config/loongarch/predicates.md
	(vect_par_cnst_even_or_odd_half): New define_predicate.
	* config/loongarch/simd.md (WVEC_HALF): New define_mode_attr.
	(simdfmt_w): Likewise.
	(zero_one): New define_int_iterator.
	(ev_od): New define_int_attr.
	(simd_<optab>w_evod_<mode:IVEC>_<su>): New define_insn.
	(<simd_isa>_<x>v<optab>w<ev_od>_<simdfmt_w>_<simdfmt><u>): New
	define_expand.
	(simd_<optab>w_evod_<mode>_hetero): New define_insn.
	(<simd_isa>_<x>v<optab>w<ev_od>_<simdfmt_w>_<simdfmt>u_<simdfmt>):
	New define_expand.
	(DIVEC): New define_mode_iterator.
	(<simd_isa>_<optab>w<ev_od>_q_d<u>_punned): New define_expand.
	(<simd_isa>_<optab>w<ev_od>_q_du_d_punned): Likewise.
	* config/loongarch/loongarch-builtins.cc
	(CODE_FOR_lsx_vaddwev_q_d): Define as a macro to override it
	with the punned expand.
	(CODE_FOR_lsx_vaddwev_q_du): Likewise.
	(CODE_FOR_lsx_vsubwev_q_d): Likewise.
	(CODE_FOR_lsx_vsubwev_q_du): Likewise.
	(CODE_FOR_lsx_vmulwev_q_d): Likewise.
	(CODE_FOR_lsx_vmulwev_q_du): Likewise.
	(CODE_FOR_lsx_vaddwod_q_d): Likewise.
	(CODE_FOR_lsx_vaddwod_q_du): Likewise.
	(CODE_FOR_lsx_vsubwod_q_d): Likewise.
	(CODE_FOR_lsx_vsubwod_q_du): Likewise.
	(CODE_FOR_lsx_vmulwod_q_d): Likewise.
	(CODE_FOR_lsx_vmulwod_q_du): Likewise.
	(CODE_FOR_lsx_vaddwev_q_du_d): Likewise.
	(CODE_FOR_lsx_vmulwev_q_du_d): Likewise.
	(CODE_FOR_lsx_vaddwod_q_du_d): Likewise.
	(CODE_FOR_lsx_vmulwod_q_du_d): Likewise.
	(CODE_FOR_lasx_xvaddwev_q_d): Likewise.
	(CODE_FOR_lasx_xvaddwev_q_du): Likewise.
	(CODE_FOR_lasx_xvsubwev_q_d): Likewise.
	(CODE_FOR_lasx_xvsubwev_q_du): Likewise.
	(CODE_FOR_lasx_xvmulwev_q_d): Likewise.
	(CODE_FOR_lasx_xvmulwev_q_du): Likewise.
	(CODE_FOR_lasx_xvaddwod_q_d): Likewise.
	(CODE_FOR_lasx_xvaddwod_q_du): Likewise.
	(CODE_FOR_lasx_xvsubwod_q_d): Likewise.
	(CODE_FOR_lasx_xvsubwod_q_du): Likewise.
	(CODE_FOR_lasx_xvmulwod_q_d): Likewise.
	(CODE_FOR_lasx_xvmulwod_q_du): Likewise.
	(CODE_FOR_lasx_xvaddwev_q_du_d): Likewise.
	(CODE_FOR_lasx_xvmulwev_q_du_d): Likewise.
	(CODE_FOR_lasx_xvaddwod_q_du_d): Likewise.
	(CODE_FOR_lasx_xvmulwod_q_du_d): Likewise.