RISC-V: Add T-Head CMO 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 XTheadCmo extension, a collection of T-Head specific
cache management operations.
The 'th' prefix and the "XTheadCmo" extension are documented in a PR
for the RISC-V toolchain conventions ([1]).

In total XTheadCmo introduces the following 21 instructions:

* DCACHE.{C,CI,I}ALL
* DCACHE.{C,CI,I}{PA,VA,SW} rs1
* DCACHE.C{PAL1,VAL1} rs1
* ICACHE.I{ALL,ALLS}
* ICACHE.I{PA,VA} rs1
* L2CACHE.{C,CI,I}ALL

Contrary to Zicbom, the XTheadCmo instructions don't have a constant
displacement, therefore we have a different syntax for the arguments.
To clarify this is intended behaviour, there is a set of negative test
for Zicbom-style arguments in x-thead-cmo-fail.s.

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

v2:
- Add missing DECLARE_INSN() list
- Fix ordering

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

1 files changed, 5 insertions, 0 deletions

diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
index cb3a980..82891f3 100644
--- a/bfd/elfxx-riscv.c
+++ b/bfd/elfxx-riscv.c
@@ -1224,6 +1224,7 @@ static struct riscv_supported_ext riscv_supported_std_zxm_ext[] =
 
 static struct riscv_supported_ext riscv_supported_vendor_x_ext[] =
 {
+  {"xtheadcmo",		ISA_SPEC_CLASS_DRAFT,	1, 0, 0 },
   {NULL, 0, 0, 0, 0}
 };
 
@@ -2386,6 +2387,8 @@ riscv_multi_subset_supports (riscv_parse_subset_t *rps,
       return riscv_subset_supports (rps, "svinval");
     case INSN_CLASS_H:
       return riscv_subset_supports (rps, "h");
+    case INSN_CLASS_XTHEADCMO:
+      return riscv_subset_supports (rps, "xtheadcmo");
     default:
       rps->error_handler
         (_("internal: unreachable INSN_CLASS_*"));
@@ -2513,6 +2516,8 @@ riscv_multi_subset_supports_ext (riscv_parse_subset_t *rps,
       return "svinval";
     case INSN_CLASS_H:
       return _("h");
+    case INSN_CLASS_XTHEADCMO:
+      return "xtheadcmo";
     default:
       rps->error_handler
         (_("internal: unreachable INSN_CLASS_*"));