RISC-V: Add support for xtheadvector-specific intrinsics.

RISC-V: Add support for xtheadvector-specific intrinsics.

This patch only involves the generation of xtheadvector
special load/store instructions and vext instructions.

gcc/ChangeLog:

	* config/riscv/riscv-vector-builtins-bases.cc
	(class th_loadstore_width): Define new builtin bases.
	(class th_extract): Define new builtin bases.
	(BASE): Define new builtin bases.
	* config/riscv/riscv-vector-builtins-bases.h:
	Define new builtin class.
	* config/riscv/riscv-vector-builtins-shapes.cc
	(struct th_loadstore_width_def): Define new builtin shapes.
	(struct th_indexed_loadstore_width_def):
	Define new builtin shapes.
	(struct th_extract_def): Define new builtin shapes.
	(SHAPE): Define new builtin shapes.
	* config/riscv/riscv-vector-builtins-shapes.h:
	Define new builtin shapes.
	* config/riscv/riscv-vector-builtins.cc (DEF_RVV_FUNCTION):
	Redefine DEF_RVV_FUNCTION for XTheadVector special intrinsics.
	* config/riscv/riscv-vector-builtins.h
	(enum required_ext): Add new XTheadVector member.
	(struct function_group_info): Likewise.
	* config/riscv/t-riscv:
	Add thead-vector-builtins-functions.def
	* config/riscv/thead-vector.md
	(@pred_mov_width<vlmem_op_attr><mode>): Add new patterns.
	(*pred_mov_width<vlmem_op_attr><mode>): Likewise.
	(@pred_store_width<vlmem_op_attr><mode>): Likewise.
	(@pred_strided_load_width<vlmem_op_attr><mode>): Likewise.
	(@pred_strided_store_width<vlmem_op_attr><mode>): Likewise.
	(@pred_indexed_load_width<vlmem_op_attr><mode>): Likewise.
	(@pred_th_extract<mode>): Likewise.
	(*pred_th_extract<mode>): Likewise.
	* config/riscv/thead-vector-builtins-functions.def: New file.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/xtheadvector/vlb-vsb.c: New test.
	* gcc.target/riscv/rvv/xtheadvector/vlbu-vsb.c: New test.
	* gcc.target/riscv/rvv/xtheadvector/vlh-vsh.c: New test.
	* gcc.target/riscv/rvv/xtheadvector/vlhu-vsh.c: New test.
	* gcc.target/riscv/rvv/xtheadvector/vlw-vsw.c: New test.
	* gcc.target/riscv/rvv/xtheadvector/vlwu-vsw.c: New test.

Co-authored-by: Jin Ma <jinma@linux.alibaba.com>
Co-authored-by: Xianmiao Qu <cooper.qu@linux.alibaba.com>
Co-authored-by: Christoph Müllner <christoph.muellner@vrull.eu>