RISC-V: Add sub-extension XTheadZvamo for T-Head VECTOR vendor extension

T-Head has a range of vendor-specific instructions. Therefore
it makes sense to group them into smaller chunks in form of
vendor extensions.

This patch adds the sub-extension "XTheadZvamo" for the
"XTheadVector" extension, and it provides AMO instructions
for T-Head VECTOR vendor extension. The 'th' prefix and the
"XTheadVector" extension are documented in a PR for the
RISC-V toolchain conventions ([1]).

[1] https://github.com/riscv-non-isa/riscv-toolchain-conventions/pull/19

Co-developed-by: Lifang Xia <lifang_xia@linux.alibaba.com>
Co-developed-by: Christoph Müllner <christoph.muellner@vrull.eu>

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_multi_subset_supports): Add support
	for "XTheadZvamo" extension.
	(riscv_multi_subset_supports_ext): Likewise.

gas/ChangeLog:

	* doc/c-riscv.texi:
	* testsuite/gas/riscv/x-thead-vector-zvamo.d: New test.
	* testsuite/gas/riscv/x-thead-vector-zvamo.s: New test.

include/ChangeLog:

	* opcode/riscv-opc.h (MATCH_TH_VAMOADDWV): New.
	* opcode/riscv.h (enum riscv_insn_class): Add insn class.

opcodes/ChangeLog:

	* riscv-opc.c: Likewise.

0 files changed, 0 insertions, 0 deletions