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.

1 files changed, 5 insertions, 0 deletions

diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
index e2c3ffe..97219b6 100644
--- a/bfd/elfxx-riscv.c
+++ b/bfd/elfxx-riscv.c
@@ -1374,6 +1374,7 @@ static struct riscv_supported_ext riscv_supported_vendor_x_ext[] =
   {"xtheadmempair",	ISA_SPEC_CLASS_DRAFT,	1, 0, 0 },
   {"xtheadsync",	ISA_SPEC_CLASS_DRAFT,	1, 0, 0 },
   {"xtheadvector",	ISA_SPEC_CLASS_DRAFT,	1, 0, 0 },
+  {"xtheadzvamo",	ISA_SPEC_CLASS_DRAFT,	1, 0, 0 },
   {"xventanacondops",	ISA_SPEC_CLASS_DRAFT,	1, 0, 0 },
   {NULL, 0, 0, 0, 0}
 };
@@ -2590,6 +2591,8 @@ riscv_multi_subset_supports (riscv_parse_subset_t *rps,
       return riscv_subset_supports (rps, "xtheadsync");
     case INSN_CLASS_XTHEADVECTOR:
       return riscv_subset_supports (rps, "xtheadvector");
+    case INSN_CLASS_XTHEADZVAMO:
+      return riscv_subset_supports (rps, "xtheadzvamo");
     case INSN_CLASS_XVENTANACONDOPS:
       return riscv_subset_supports (rps, "xventanacondops");
     default:
@@ -2836,6 +2839,8 @@ riscv_multi_subset_supports_ext (riscv_parse_subset_t *rps,
       return "xtheadsync";
     case INSN_CLASS_XTHEADVECTOR:
       return "xtheadvector";
+    case INSN_CLASS_XTHEADZVAMO:
+      return "xtheadzvamo";
     default:
       rps->error_handler
         (_("internal: unreachable INSN_CLASS_*"));