[Integration,1/2] RISC-V: add vendor opcodes

Message ID 20210903030001.439-2-lifang_xia@c-sky.com
State New
Headers show
Series
  • RISC-V: Add vendor(T-HEAD) opcodes
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Commit Message

=?UTF-8?B?5aSP56uL5pa5?= Sept. 3, 2021, 3 a.m.
This patch uses the T-HEAD Xuantie processor as an example to solve that
how to add the vendor's opcode and CSR.
Without modifying the existing mechanism, create a new
opcodes/riscv-vendor-opc.c, similar to opcodes/riscv-opc.c, used to
describe the vendor's opcodes.
New file, include/opcodes/riscv-vendor-opc.h, used to define the encoding,
mask and CSR of the opcodes.

The sub-string from -march option is used to pick the suitable list of
the vendor's opcodes.

bfd/
	* cpu-riscv.h (enum riscv_spec_class): New
	ISA_SPEC_CLASS_VENDOR.
gas/
	* config/tc-riscv.c (ext_version_table): New "theadc".
	(riscv_vendor_get_opcodes): New.
	(riscv_multi_subset_supports): Check xtheadc extensions.
	(riscv_get_default_ext_version): Skip for vendor.
	(init_opcode_hash): Add vendor's extensions to the hash.
	(md_begin): Init opcode hash.
include/
	* opcode/riscv-opc.h: Include riscv-vendor-opc.h
	* opcode/riscv-vendor-opc.h: New.
	* opcode/riscv.h (enum riscv_extended_insn_class): New class for vendor.
	(struct riscv_vendor_opcode): New.
	(riscv_vendor_list): New.
opcodes/
	* Makefile.am: Add riscv-vendor-opc.c.
	* Makefile.in: Likewise.
	* configure: Likewise
	* configure.ac: Likewise
	* riscv-dis.c (arch_string): New.
	(get_vendor_opcodes): Get the vendor opcodes.
	(riscv_disassemble_insn): Add vendor's opcode to the hash.
	(riscv_get_disassembler): Setup arch_string with attr.
	* riscv-vendor-opc.c: New.
---
 bfd/cpu-riscv.h                   |  1 +
 gas/config/tc-riscv.c             | 55 +++++++++++++++++++++++++++++--
 include/opcode/riscv-opc.h        |  1 +
 include/opcode/riscv-vendor-opc.h | 34 +++++++++++++++++++
 include/opcode/riscv.h            | 10 ++++++
 opcodes/Makefile.am               |  1 +
 opcodes/Makefile.in               |  2 ++
 opcodes/configure                 |  2 +-
 opcodes/configure.ac              |  2 +-
 opcodes/riscv-dis.c               | 23 +++++++++++++
 opcodes/riscv-vendor-opc.c        | 43 ++++++++++++++++++++++++
 11 files changed, 170 insertions(+), 4 deletions(-)
 create mode 100644 include/opcode/riscv-vendor-opc.h
 create mode 100644 opcodes/riscv-vendor-opc.c

-- 
2.17.1

Comments

Nelson Chu Sept. 3, 2021, 4 a.m. | #1
On Fri, Sep 3, 2021 at 11:00 AM Lifang Xia <lifang_xia@c-sky.com> wrote:
>

> This patch uses the T-HEAD Xuantie processor as an example to solve that

> how to add the vendor's opcode and CSR.

> Without modifying the existing mechanism, create a new

> opcodes/riscv-vendor-opc.c, similar to opcodes/riscv-opc.c, used to

> describe the vendor's opcodes.

> New file, include/opcodes/riscv-vendor-opc.h, used to define the encoding,

> mask and CSR of the opcodes.

>

> The sub-string from -march option is used to pick the suitable list of

> the vendor's opcodes.

>

> bfd/

>         * cpu-riscv.h (enum riscv_spec_class): New

>         ISA_SPEC_CLASS_VENDOR.

> gas/

>         * config/tc-riscv.c (ext_version_table): New "theadc".

>         (riscv_vendor_get_opcodes): New.

>         (riscv_multi_subset_supports): Check xtheadc extensions.

>         (riscv_get_default_ext_version): Skip for vendor.

>         (init_opcode_hash): Add vendor's extensions to the hash.

>         (md_begin): Init opcode hash.

> include/

>         * opcode/riscv-opc.h: Include riscv-vendor-opc.h

>         * opcode/riscv-vendor-opc.h: New.

>         * opcode/riscv.h (enum riscv_extended_insn_class): New class for vendor.

>         (struct riscv_vendor_opcode): New.

>         (riscv_vendor_list): New.

> opcodes/

>         * Makefile.am: Add riscv-vendor-opc.c.

>         * Makefile.in: Likewise.

>         * configure: Likewise

>         * configure.ac: Likewise

>         * riscv-dis.c (arch_string): New.

>         (get_vendor_opcodes): Get the vendor opcodes.

>         (riscv_disassemble_insn): Add vendor's opcode to the hash.

>         (riscv_get_disassembler): Setup arch_string with attr.

>         * riscv-vendor-opc.c: New.

> ---

>  bfd/cpu-riscv.h                   |  1 +

>  gas/config/tc-riscv.c             | 55 +++++++++++++++++++++++++++++--

>  include/opcode/riscv-opc.h        |  1 +

>  include/opcode/riscv-vendor-opc.h | 34 +++++++++++++++++++

>  include/opcode/riscv.h            | 10 ++++++

>  opcodes/Makefile.am               |  1 +

>  opcodes/Makefile.in               |  2 ++

>  opcodes/configure                 |  2 +-

>  opcodes/configure.ac              |  2 +-

>  opcodes/riscv-dis.c               | 23 +++++++++++++

>  opcodes/riscv-vendor-opc.c        | 43 ++++++++++++++++++++++++

>  11 files changed, 170 insertions(+), 4 deletions(-)

>  create mode 100644 include/opcode/riscv-vendor-opc.h

>  create mode 100644 opcodes/riscv-vendor-opc.c

>

> diff --git a/bfd/cpu-riscv.h b/bfd/cpu-riscv.h

> index cafaca23be0..06ede1b2bef 100644

> --- a/bfd/cpu-riscv.h

> +++ b/bfd/cpu-riscv.h

> @@ -26,6 +26,7 @@ enum riscv_spec_class

>    ISA_SPEC_CLASS_20190608,

>    ISA_SPEC_CLASS_20191213,

>    ISA_SPEC_CLASS_DRAFT,

> +  ISA_SPEC_CLASS_VENDOR,


The basic idea of riscv_spec_class is that -  Every spec should have
their own names and versions, so the ISA_SPEC is riscv ISA spec,
PRIV_SPEC is the privileged spec, we also may have DEBUG_SPEC for
debug.  Therefore, each vendor should have it's own <VENDOR_NAME>_SPEC
and versions.  For example, maybe SIFIVE_XXX_SPEC_1p0, ....  The riscv
isa spec doesn't define vendor stuff, so ISA_SPEC_CLASS_VENDOR isn't
suitable for me.

>    /* Privileged spec.  */

>    PRIV_SPEC_CLASS_NONE,

> diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c

> index 18992949954..99bc9298b16 100644

> --- a/gas/config/tc-riscv.c

> +++ b/gas/config/tc-riscv.c

> @@ -157,6 +157,9 @@ static const struct riscv_ext_version ext_version_table[] =

>    {"zba",   ISA_SPEC_CLASS_DRAFT, 0, 93},

>    {"zbc",   ISA_SPEC_CLASS_DRAFT, 0, 93},

>

> +  /* T-HEAD extentions for Xuantie C9xx.  */

> +  {"xtheadc",   ISA_SPEC_CLASS_VENDOR, 2, 0},


Likewise.

>    /* Terminate the list.  */

>    {NULL, 0, 0, 0}

>  };

> @@ -238,6 +241,22 @@ riscv_set_default_isa_spec (const char *s)

>    return 1;

>  }

>

> +/* Get the opcodes from vendors.  */

> +static struct riscv_opcode *

> +riscv_vendor_get_opcodes (riscv_subset_list_t *subsets)

> +{

> +  unsigned int i = 0;

> +  struct riscv_subset_t *subset = NULL;

> +

> +  for (i = 0; riscv_vendor_list[i].vendor; i++)

> +    {

> +      if (riscv_lookup_subset (subsets, riscv_vendor_list[i].vendor, &subset))

> +       return riscv_vendor_list[i].opcodes;

> +    }

> +

> +  return NULL;

> +}


Each function should have the corresponding extended function, which
is used to handle draft or vendor stuff.  Could you port your vendor
extensions into these extended functions?  For your
riscv_vendor_get_opcodes, you just need to add your vendor opcodes
into riscv_extended_opcodes, and then update the
riscv_find_extended_opcode_hash.  You don't need to build the whole
vendor structures again, I suppose the extended functions should be
enough to handle most of the vendor extensions, except the vendor
relocations.

>  /* Set the default_priv_spec.  Find the privileged elf attributes when

>     the input string is NULL.  Return 0 if the spec isn't supported.

>     Otherwise, return 1.  */

> @@ -407,6 +426,9 @@ riscv_multi_subset_supports (enum riscv_insn_class insn_class)

>      case INSN_CLASS_ZBC:

>        return riscv_subset_supports ("zbc");

>

> +    case INSN_CLASS_THEADC:

> +      return riscv_subset_supports ("xtheadc");


Likewise, it is better to be added in the riscv_extended_subset_supports.

>      default:

>        return riscv_extended_subset_supports (insn_class);

>      }

> @@ -458,6 +480,7 @@ riscv_search_ext_version_hash (const char *name,

>          && strcmp (ext->name, name) == 0)

>      {

>        if (ext->isa_spec_class == ISA_SPEC_CLASS_DRAFT

> +         || ext->isa_spec_class == ISA_SPEC_CLASS_VENDOR

>           || ext->isa_spec_class == default_isa_spec)

>         {

>           *major_version = ext->major_version;

> @@ -1328,6 +1351,7 @@ struct percent_op_match

>

>  static htab_t

>  init_opcode_hash (const struct riscv_opcode *opcodes,

> +                 const struct riscv_opcode *ext_opcodes,

>                   bool insn_directive_p)

>  {

>    int i = 0;

> @@ -1358,6 +1382,29 @@ init_opcode_hash (const struct riscv_opcode *opcodes,

>        while (opcodes[i].name && !strcmp (opcodes[i].name, name));

>      }

>

> +  i = 0;

> +  while (ext_opcodes && ext_opcodes[i].name)

> +    {

> +      const char *name = ext_opcodes[i].name;

> +      if (str_hash_insert (hash, name, &ext_opcodes[i], 0) != NULL)

> +       as_fatal (_("internal: duplicate %s"), name);

> +

> +      do

> +       {

> +         if (ext_opcodes[i].pinfo != INSN_MACRO)

> +           {

> +             length = 0; /* Let assembler determine the length.  */

> +             if (!validate_riscv_insn (&ext_opcodes[i], length))

> +               as_fatal (_("internal: broken assembler.  "

> +                           "No assembly attempted"));

> +           }

> +         else

> +           gas_assert (!insn_directive_p);

> +         ++i;

> +       }

> +      while (ext_opcodes[i].name && !strcmp (ext_opcodes[i].name, name));

> +    }

> +

>    return hash;

>  }


Please check the md_begin, and see how draft extensions are
initialized.  I think you can create a new vendor opcode hash, and
just call the init_opcode_hash.

> @@ -1372,8 +1419,11 @@ md_begin (void)

>    if (! bfd_set_arch_mach (stdoutput, bfd_arch_riscv, mach))

>      as_warn (_("could not set architecture and machine"));

>

> -  op_hash = init_opcode_hash (riscv_opcodes, false);

> -  insn_type_hash = init_opcode_hash (riscv_insn_types, true);

> +  op_hash = init_opcode_hash (riscv_opcodes,

> +                             riscv_vendor_get_opcodes (&riscv_subsets),

> +                             false);

> +

> +  insn_type_hash = init_opcode_hash (riscv_insn_types, NULL, true);


Likewise, don't need to change this.

>    reg_names_hash = str_htab_create ();

>    hash_reg_names (RCLASS_GPR, riscv_gpr_names_numeric, NGPR);

> @@ -4587,3 +4637,4 @@ riscv_pop_insert (void)

>

>    pop_insert (riscv_pseudo_table);

>  }

> +

> diff --git a/include/opcode/riscv-opc.h b/include/opcode/riscv-opc.h

> index 9999da6241a..84fc2ee0e8e 100644

> --- a/include/opcode/riscv-opc.h

> +++ b/include/opcode/riscv-opc.h

> @@ -20,6 +20,7 @@

>

>  #ifndef RISCV_ENCODING_H

>  #define RISCV_ENCODING_H

> +#include "opcode/riscv-vendor-opc.h"

>  /* Instruction opcode macros.  */

>  #define MATCH_SLLI_RV32 0x1013

>  #define MASK_SLLI_RV32  0xfe00707f

> diff --git a/include/opcode/riscv-vendor-opc.h b/include/opcode/riscv-vendor-opc.h


Could these encodings be added in the riscv-opc-extended.h?

> new file mode 100644

> index 00000000000..949047239f8

> --- /dev/null

> +++ b/include/opcode/riscv-vendor-opc.h

> @@ -0,0 +1,34 @@

> +/* riscv-vendor-opc.h.  RISC-V instruction opcode and CSR macros from vendors.

> +   Copyright (C) 2011-2021 Free Software Foundation, Inc.

> +   Contributed by Andrew Waterman

> +

> +   This file is part of GDB, GAS, and the GNU binutils.

> +

> +   GDB, GAS, and the GNU binutils are free software; you can redistribute

> +   them and/or modify them under the terms of the GNU General Public

> +   License as published by the Free Software Foundation; either version

> +   3, or (at your option) any later version.

> +

> +   GDB, GAS, and the GNU binutils are distributed in the hope that they

> +   will be useful, but WITHOUT ANY WARRANTY; without even the implied

> +   warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See

> +   the GNU General Public License for more details.

> +

> +   You should have received a copy of the GNU General Public License

> +   along with this program; see the file COPYING3. If not,

> +   see <http://www.gnu.org/licenses/>.  */

> +

> +#ifndef __RISCV_VENDOR_OPC_H__

> +#define __RISCV_VENDOR_OPC_H__

> +

> +

> +/* Opcodes for VENDOR 0.  */

> +

> +

> +/* Opcodes for VENDOR 1.  */

> +

> +

> +/* Opcodes for VENDOR 2.  */

> +

> +

> +#endif

> diff --git a/include/opcode/riscv.h b/include/opcode/riscv.h

> index 8d5251c50e4..af8df794d1b 100644

> --- a/include/opcode/riscv.h

> +++ b/include/opcode/riscv.h


I think just updating the extended structures and classes should be enough.

> @@ -361,6 +361,12 @@ struct riscv_opcode

>    unsigned long pinfo;

>  };

>

> +struct riscv_vendor_opcode

> +{

> +  const char *vendor;

> +  struct riscv_opcode *opcodes;

> +};

> +

>  /* Instruction is a simple alias (e.g. "mv" for "addi").  */

>  #define        INSN_ALIAS              0x00000001

>

> @@ -434,6 +440,7 @@ extern const char * const riscv_fpr_names_abi[NFPR];

>

>  extern const struct riscv_opcode riscv_opcodes[];

>  extern const struct riscv_opcode riscv_insn_types[];

> +extern const struct riscv_vendor_opcode riscv_vendor_list[];


You don't need to add this, just add your vendor opcodes into
riscv_extended_opcodes in the opcodes/riscv-opc.c.

>  /* Extended extensions.  */

>

> @@ -496,6 +503,9 @@ enum riscv_extended_insn_class

>    INSN_CLASS_D_AND_ZFH,

>    INSN_CLASS_Q_AND_ZFH,

>    INSN_CLASS_SVINVAL,

> +

> +  /* INSN class for THEAD.  */

> +  INSN_CLASS_THEADC,

>  };


Yes, this one is good, added vendor stuff into extended classes is
what I suggest.

>  /* This is a list of macro expanded instructions for extended

> diff --git a/opcodes/Makefile.am b/opcodes/Makefile.am

> index 0e04b4c05c4..4f3ad0e69cd 100644

> --- a/opcodes/Makefile.am

> +++ b/opcodes/Makefile.am

> @@ -229,6 +229,7 @@ TARGET_LIBOPCODES_CFILES = \

>         pru-opc.c \

>         riscv-dis.c \

>         riscv-opc.c \

> +       riscv-vendor-opc.c \

>         rl78-decode.c \

>         rl78-dis.c \

>         rx-decode.c \

> diff --git a/opcodes/Makefile.in b/opcodes/Makefile.in

> index 42c15f00d30..5dcbc204a1e 100644

> --- a/opcodes/Makefile.in

> +++ b/opcodes/Makefile.in

> @@ -620,6 +620,7 @@ TARGET_LIBOPCODES_CFILES = \

>         pru-opc.c \

>         riscv-dis.c \

>         riscv-opc.c \

> +       riscv-vendor-opc.c \

>         rl78-decode.c \

>         rl78-dis.c \

>         rx-decode.c \

> @@ -1036,6 +1037,7 @@ distclean-compile:

>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/pru-opc.Plo@am__quote@

>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/riscv-dis.Plo@am__quote@

>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/riscv-opc.Plo@am__quote@

> +@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/riscv-vendor-opc.Plo@am__quote@

>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/rl78-decode.Plo@am__quote@

>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/rl78-dis.Plo@am__quote@

>  @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/rx-decode.Plo@am__quote@

> diff --git a/opcodes/configure b/opcodes/configure

> index 3513e408ce1..ad9ec966411 100755

> --- a/opcodes/configure

> +++ b/opcodes/configure

> @@ -12265,7 +12265,7 @@ if test x${all_targets} = xfalse ; then

>         bfd_pru_arch)           ta="$ta pru-dis.lo pru-opc.lo" ;;

>         bfd_pyramid_arch)       ;;

>         bfd_romp_arch)          ;;

> -       bfd_riscv_arch)         ta="$ta riscv-dis.lo riscv-opc.lo" ;;

> +       bfd_riscv_arch)         ta="$ta riscv-dis.lo riscv-opc.lo riscv-vendor-opc.lo" ;;

>         bfd_rs6000_arch)        ta="$ta ppc-dis.lo ppc-opc.lo" ;;

>         bfd_rl78_arch)          ta="$ta rl78-dis.lo rl78-decode.lo";;

>         bfd_rx_arch)            ta="$ta rx-dis.lo rx-decode.lo";;

> diff --git a/opcodes/configure.ac b/opcodes/configure.ac

> index e564f067334..16024f2f0d5 100644

> --- a/opcodes/configure.ac

> +++ b/opcodes/configure.ac

> @@ -326,7 +326,7 @@ if test x${all_targets} = xfalse ; then

>         bfd_pru_arch)           ta="$ta pru-dis.lo pru-opc.lo" ;;

>         bfd_pyramid_arch)       ;;

>         bfd_romp_arch)          ;;

> -       bfd_riscv_arch)         ta="$ta riscv-dis.lo riscv-opc.lo" ;;

> +       bfd_riscv_arch)         ta="$ta riscv-dis.lo riscv-opc.lo riscv-vendor-opc.lo" ;;

>         bfd_rs6000_arch)        ta="$ta ppc-dis.lo ppc-opc.lo" ;;

>         bfd_rl78_arch)          ta="$ta rl78-dis.lo rl78-decode.lo";;

>         bfd_rx_arch)            ta="$ta rx-dis.lo rx-decode.lo";;


We all have a consensus that no longer need to add new files for draft
and vendor stuff.  I cannot find the first mailing discussions about
my first integration patches, but you can see this one:
https://sourceware.org/pipermail/binutils/2021-March/115990.html.
Anyway, I suppose all you need to do is to port vendor extensions into
the existing extended functions.

> diff --git a/opcodes/riscv-dis.c b/opcodes/riscv-dis.c

> index dcc5a09213b..8ddc6bec370 100644

> --- a/opcodes/riscv-dis.c

> +++ b/opcodes/riscv-dis.c

> @@ -33,6 +33,7 @@

>  #include <ctype.h>

>

>  static enum riscv_spec_class default_priv_spec = PRIV_SPEC_CLASS_NONE;

> +static const char *arch_string = NULL;

>

>  struct riscv_private_data

>  {

> @@ -140,6 +141,21 @@ parse_riscv_dis_options (const char *opts_in)

>    free (opts);

>  }

>

> +static struct riscv_opcode*

> +get_vendor_opcodes (const char *arch)

> +{

> +  int i = 0;

> +  if (arch == NULL)

> +    return NULL;

> +

> +  for (i = 0; riscv_vendor_list[i].vendor; i++)

> +    {

> +      if (strstr(arch, riscv_vendor_list[i].vendor) != NULL)

> +       return riscv_vendor_list[i].opcodes;

> +    }

> +  return NULL;

> +}

> +

>  /* Print one argument from an array.  */

>

>  static void

> @@ -548,6 +564,11 @@ riscv_disassemble_opcode (insn_t word,

>         if (!riscv_hash[OP_HASH_IDX (op->match)])

>           riscv_hash[OP_HASH_IDX (op->match)] = op;

>

> +      op = get_vendor_opcodes (arch_string);

> +      for (; op && op->name; op++)

> +       if (!riscv_hash[OP_HASH_IDX (op->match)])

> +         riscv_hash[OP_HASH_IDX (op->match)] = op;

> +

>        init = 1;

>      }

>

> @@ -744,6 +765,8 @@ riscv_get_disassembler (bfd *abfd)

>                                                       attr[Tag_b].i,

>                                                       attr[Tag_c].i,

>                                                       &default_priv_spec);

> +             /* Get Vendor opcodes.  */

> +             arch_string = attr[Tag_RISCV_arch].s;

>             }

>          }

>      }


Likewise, if you add your vendor opcode into the
riscv_extended_opcodes, then you don't need to do anything here,
except that you have vendor operands.  Then you will need to update
your vendor operands in print_extended_insn_args, that's all.

> diff --git a/opcodes/riscv-vendor-opc.c b/opcodes/riscv-vendor-opc.c

> new file mode 100644

> index 00000000000..9191b654c14

> --- /dev/null

> +++ b/opcodes/riscv-vendor-opc.c

> @@ -0,0 +1,43 @@

> +/* RISC-V opcode list from vendors.

> +   Copyright (C) 2011-2021 Free Software Foundation, Inc.

> +

> +   Contributed by Andrew Waterman (andrew@sifive.com).

> +   Based on MIPS target.

> +

> +   This file is part of the GNU opcodes library.

> +

> +   This library is free software; you can redistribute it and/or modify

> +   it under the terms of the GNU General Public License as published by

> +   the Free Software Foundation; either version 3, or (at your option)

> +   any later version.

> +

> +   It is distributed in the hope that it will be useful, but WITHOUT

> +   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

> +   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public

> +   License for more details.

> +

> +   You should have received a copy of the GNU General Public License

> +   along with this program; see the file COPYING3. If not,

> +   see <http://www.gnu.org/licenses/>.  */

> +

> +

> +#include "sysdep.h"

> +#include "opcode/riscv.h"

> +#include <stdio.h>

> +#include "bfd.h"

> +

> +/* The vendor extension opcodes for T-HEAD.  */

> +struct riscv_opcode vendor_thead_opcodes[] =

> +{

> +  {0, 0, INSN_CLASS_NONE, 0, 0, 0, 0, 0}

> +

> +};

> +

> +/* The vendor opcodes list.  */

> +const struct riscv_vendor_opcode riscv_vendor_list[] =

> +{

> +  /* Vendor T-HEAD.  */

> +  {"xtheadc", vendor_thead_opcodes},

> +  {NULL, NULL},

> +};

> +

> --

> 2.17.1

>

Patch

diff --git a/bfd/cpu-riscv.h b/bfd/cpu-riscv.h
index cafaca23be0..06ede1b2bef 100644
--- a/bfd/cpu-riscv.h
+++ b/bfd/cpu-riscv.h
@@ -26,6 +26,7 @@  enum riscv_spec_class
   ISA_SPEC_CLASS_20190608,
   ISA_SPEC_CLASS_20191213,
   ISA_SPEC_CLASS_DRAFT,
+  ISA_SPEC_CLASS_VENDOR,
 
   /* Privileged spec.  */
   PRIV_SPEC_CLASS_NONE,
diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index 18992949954..99bc9298b16 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -157,6 +157,9 @@  static const struct riscv_ext_version ext_version_table[] =
   {"zba",   ISA_SPEC_CLASS_DRAFT, 0, 93},
   {"zbc",   ISA_SPEC_CLASS_DRAFT, 0, 93},
 
+  /* T-HEAD extentions for Xuantie C9xx.  */
+  {"xtheadc",   ISA_SPEC_CLASS_VENDOR, 2, 0},
+
   /* Terminate the list.  */
   {NULL, 0, 0, 0}
 };
@@ -238,6 +241,22 @@  riscv_set_default_isa_spec (const char *s)
   return 1;
 }
 
+/* Get the opcodes from vendors.  */
+static struct riscv_opcode *
+riscv_vendor_get_opcodes (riscv_subset_list_t *subsets)
+{
+  unsigned int i = 0;
+  struct riscv_subset_t *subset = NULL;
+
+  for (i = 0; riscv_vendor_list[i].vendor; i++)
+    {
+      if (riscv_lookup_subset (subsets, riscv_vendor_list[i].vendor, &subset))
+	return riscv_vendor_list[i].opcodes;
+    }
+
+  return NULL;
+}
+
 /* Set the default_priv_spec.  Find the privileged elf attributes when
    the input string is NULL.  Return 0 if the spec isn't supported.
    Otherwise, return 1.  */
@@ -407,6 +426,9 @@  riscv_multi_subset_supports (enum riscv_insn_class insn_class)
     case INSN_CLASS_ZBC:
       return riscv_subset_supports ("zbc");
 
+    case INSN_CLASS_THEADC:
+      return riscv_subset_supports ("xtheadc");
+
     default:
       return riscv_extended_subset_supports (insn_class);
     }
@@ -458,6 +480,7 @@  riscv_search_ext_version_hash (const char *name,
 	 && strcmp (ext->name, name) == 0)
     {
       if (ext->isa_spec_class == ISA_SPEC_CLASS_DRAFT
+	  || ext->isa_spec_class == ISA_SPEC_CLASS_VENDOR
 	  || ext->isa_spec_class == default_isa_spec)
 	{
 	  *major_version = ext->major_version;
@@ -1328,6 +1351,7 @@  struct percent_op_match
 
 static htab_t
 init_opcode_hash (const struct riscv_opcode *opcodes,
+		  const struct riscv_opcode *ext_opcodes,
 		  bool insn_directive_p)
 {
   int i = 0;
@@ -1358,6 +1382,29 @@  init_opcode_hash (const struct riscv_opcode *opcodes,
       while (opcodes[i].name && !strcmp (opcodes[i].name, name));
     }
 
+  i = 0;
+  while (ext_opcodes && ext_opcodes[i].name)
+    {
+      const char *name = ext_opcodes[i].name;
+      if (str_hash_insert (hash, name, &ext_opcodes[i], 0) != NULL)
+	as_fatal (_("internal: duplicate %s"), name);
+
+      do
+	{
+	  if (ext_opcodes[i].pinfo != INSN_MACRO)
+	    {
+	      length = 0; /* Let assembler determine the length.  */
+	      if (!validate_riscv_insn (&ext_opcodes[i], length))
+		as_fatal (_("internal: broken assembler.  "
+			    "No assembly attempted"));
+	    }
+	  else
+	    gas_assert (!insn_directive_p);
+	  ++i;
+	}
+      while (ext_opcodes[i].name && !strcmp (ext_opcodes[i].name, name));
+    }
+
   return hash;
 }
 
@@ -1372,8 +1419,11 @@  md_begin (void)
   if (! bfd_set_arch_mach (stdoutput, bfd_arch_riscv, mach))
     as_warn (_("could not set architecture and machine"));
 
-  op_hash = init_opcode_hash (riscv_opcodes, false);
-  insn_type_hash = init_opcode_hash (riscv_insn_types, true);
+  op_hash = init_opcode_hash (riscv_opcodes,
+			      riscv_vendor_get_opcodes (&riscv_subsets),
+			      false);
+
+  insn_type_hash = init_opcode_hash (riscv_insn_types, NULL, true);
 
   reg_names_hash = str_htab_create ();
   hash_reg_names (RCLASS_GPR, riscv_gpr_names_numeric, NGPR);
@@ -4587,3 +4637,4 @@  riscv_pop_insert (void)
 
   pop_insert (riscv_pseudo_table);
 }
+
diff --git a/include/opcode/riscv-opc.h b/include/opcode/riscv-opc.h
index 9999da6241a..84fc2ee0e8e 100644
--- a/include/opcode/riscv-opc.h
+++ b/include/opcode/riscv-opc.h
@@ -20,6 +20,7 @@ 
 
 #ifndef RISCV_ENCODING_H
 #define RISCV_ENCODING_H
+#include "opcode/riscv-vendor-opc.h"
 /* Instruction opcode macros.  */
 #define MATCH_SLLI_RV32 0x1013
 #define MASK_SLLI_RV32  0xfe00707f
diff --git a/include/opcode/riscv-vendor-opc.h b/include/opcode/riscv-vendor-opc.h
new file mode 100644
index 00000000000..949047239f8
--- /dev/null
+++ b/include/opcode/riscv-vendor-opc.h
@@ -0,0 +1,34 @@ 
+/* riscv-vendor-opc.h.  RISC-V instruction opcode and CSR macros from vendors.
+   Copyright (C) 2011-2021 Free Software Foundation, Inc.
+   Contributed by Andrew Waterman
+
+   This file is part of GDB, GAS, and the GNU binutils.
+
+   GDB, GAS, and the GNU binutils are free software; you can redistribute
+   them and/or modify them under the terms of the GNU General Public
+   License as published by the Free Software Foundation; either version
+   3, or (at your option) any later version.
+
+   GDB, GAS, and the GNU binutils are distributed in the hope that they
+   will be useful, but WITHOUT ANY WARRANTY; without even the implied
+   warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+   the GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; see the file COPYING3. If not,
+   see <http://www.gnu.org/licenses/>.  */
+
+#ifndef __RISCV_VENDOR_OPC_H__
+#define __RISCV_VENDOR_OPC_H__
+
+
+/* Opcodes for VENDOR 0.  */
+
+
+/* Opcodes for VENDOR 1.  */
+
+
+/* Opcodes for VENDOR 2.  */
+
+
+#endif
diff --git a/include/opcode/riscv.h b/include/opcode/riscv.h
index 8d5251c50e4..af8df794d1b 100644
--- a/include/opcode/riscv.h
+++ b/include/opcode/riscv.h
@@ -361,6 +361,12 @@  struct riscv_opcode
   unsigned long pinfo;
 };
 
+struct riscv_vendor_opcode
+{
+  const char *vendor;
+  struct riscv_opcode *opcodes;
+};
+
 /* Instruction is a simple alias (e.g. "mv" for "addi").  */
 #define	INSN_ALIAS		0x00000001
 
@@ -434,6 +440,7 @@  extern const char * const riscv_fpr_names_abi[NFPR];
 
 extern const struct riscv_opcode riscv_opcodes[];
 extern const struct riscv_opcode riscv_insn_types[];
+extern const struct riscv_vendor_opcode riscv_vendor_list[];
 
 /* Extended extensions.  */
 
@@ -496,6 +503,9 @@  enum riscv_extended_insn_class
   INSN_CLASS_D_AND_ZFH,
   INSN_CLASS_Q_AND_ZFH,
   INSN_CLASS_SVINVAL,
+
+  /* INSN class for THEAD.  */
+  INSN_CLASS_THEADC,
 };
 
 /* This is a list of macro expanded instructions for extended
diff --git a/opcodes/Makefile.am b/opcodes/Makefile.am
index 0e04b4c05c4..4f3ad0e69cd 100644
--- a/opcodes/Makefile.am
+++ b/opcodes/Makefile.am
@@ -229,6 +229,7 @@  TARGET_LIBOPCODES_CFILES = \
 	pru-opc.c \
 	riscv-dis.c \
 	riscv-opc.c \
+	riscv-vendor-opc.c \
 	rl78-decode.c \
 	rl78-dis.c \
 	rx-decode.c \
diff --git a/opcodes/Makefile.in b/opcodes/Makefile.in
index 42c15f00d30..5dcbc204a1e 100644
--- a/opcodes/Makefile.in
+++ b/opcodes/Makefile.in
@@ -620,6 +620,7 @@  TARGET_LIBOPCODES_CFILES = \
 	pru-opc.c \
 	riscv-dis.c \
 	riscv-opc.c \
+	riscv-vendor-opc.c \
 	rl78-decode.c \
 	rl78-dis.c \
 	rx-decode.c \
@@ -1036,6 +1037,7 @@  distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/pru-opc.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/riscv-dis.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/riscv-opc.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/riscv-vendor-opc.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/rl78-decode.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/rl78-dis.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/rx-decode.Plo@am__quote@
diff --git a/opcodes/configure b/opcodes/configure
index 3513e408ce1..ad9ec966411 100755
--- a/opcodes/configure
+++ b/opcodes/configure
@@ -12265,7 +12265,7 @@  if test x${all_targets} = xfalse ; then
 	bfd_pru_arch)		ta="$ta pru-dis.lo pru-opc.lo" ;;
 	bfd_pyramid_arch)	;;
 	bfd_romp_arch)		;;
-	bfd_riscv_arch)         ta="$ta riscv-dis.lo riscv-opc.lo" ;;
+	bfd_riscv_arch)         ta="$ta riscv-dis.lo riscv-opc.lo riscv-vendor-opc.lo" ;;
 	bfd_rs6000_arch)	ta="$ta ppc-dis.lo ppc-opc.lo" ;;
 	bfd_rl78_arch)		ta="$ta rl78-dis.lo rl78-decode.lo";;
 	bfd_rx_arch)		ta="$ta rx-dis.lo rx-decode.lo";;
diff --git a/opcodes/configure.ac b/opcodes/configure.ac
index e564f067334..16024f2f0d5 100644
--- a/opcodes/configure.ac
+++ b/opcodes/configure.ac
@@ -326,7 +326,7 @@  if test x${all_targets} = xfalse ; then
 	bfd_pru_arch)		ta="$ta pru-dis.lo pru-opc.lo" ;;
 	bfd_pyramid_arch)	;;
 	bfd_romp_arch)		;;
-	bfd_riscv_arch)         ta="$ta riscv-dis.lo riscv-opc.lo" ;;
+	bfd_riscv_arch)         ta="$ta riscv-dis.lo riscv-opc.lo riscv-vendor-opc.lo" ;;
 	bfd_rs6000_arch)	ta="$ta ppc-dis.lo ppc-opc.lo" ;;
 	bfd_rl78_arch)		ta="$ta rl78-dis.lo rl78-decode.lo";;
 	bfd_rx_arch)		ta="$ta rx-dis.lo rx-decode.lo";;
diff --git a/opcodes/riscv-dis.c b/opcodes/riscv-dis.c
index dcc5a09213b..8ddc6bec370 100644
--- a/opcodes/riscv-dis.c
+++ b/opcodes/riscv-dis.c
@@ -33,6 +33,7 @@ 
 #include <ctype.h>
 
 static enum riscv_spec_class default_priv_spec = PRIV_SPEC_CLASS_NONE;
+static const char *arch_string = NULL;
 
 struct riscv_private_data
 {
@@ -140,6 +141,21 @@  parse_riscv_dis_options (const char *opts_in)
   free (opts);
 }
 
+static struct riscv_opcode*
+get_vendor_opcodes (const char *arch)
+{
+  int i = 0;
+  if (arch == NULL)
+    return NULL;
+
+  for (i = 0; riscv_vendor_list[i].vendor; i++)
+    {
+      if (strstr(arch, riscv_vendor_list[i].vendor) != NULL)
+	return riscv_vendor_list[i].opcodes;
+    }
+  return NULL;
+}
+
 /* Print one argument from an array.  */
 
 static void
@@ -548,6 +564,11 @@  riscv_disassemble_opcode (insn_t word,
 	if (!riscv_hash[OP_HASH_IDX (op->match)])
 	  riscv_hash[OP_HASH_IDX (op->match)] = op;
 
+      op = get_vendor_opcodes (arch_string);
+      for (; op && op->name; op++)
+	if (!riscv_hash[OP_HASH_IDX (op->match)])
+	  riscv_hash[OP_HASH_IDX (op->match)] = op;
+
       init = 1;
     }
 
@@ -744,6 +765,8 @@  riscv_get_disassembler (bfd *abfd)
 						      attr[Tag_b].i,
 						      attr[Tag_c].i,
 						      &default_priv_spec);
+	      /* Get Vendor opcodes.  */
+	      arch_string = attr[Tag_RISCV_arch].s;
 	    }
         }
     }
diff --git a/opcodes/riscv-vendor-opc.c b/opcodes/riscv-vendor-opc.c
new file mode 100644
index 00000000000..9191b654c14
--- /dev/null
+++ b/opcodes/riscv-vendor-opc.c
@@ -0,0 +1,43 @@ 
+/* RISC-V opcode list from vendors.
+   Copyright (C) 2011-2021 Free Software Foundation, Inc.
+
+   Contributed by Andrew Waterman (andrew@sifive.com).
+   Based on MIPS target.
+
+   This file is part of the GNU opcodes library.
+
+   This library is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   It is distributed in the hope that it will be useful, but WITHOUT
+   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+   License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; see the file COPYING3. If not,
+   see <http://www.gnu.org/licenses/>.  */
+
+
+#include "sysdep.h"
+#include "opcode/riscv.h"
+#include <stdio.h>
+#include "bfd.h"
+
+/* The vendor extension opcodes for T-HEAD.  */
+struct riscv_opcode vendor_thead_opcodes[] =
+{
+  {0, 0, INSN_CLASS_NONE, 0, 0, 0, 0, 0}
+
+};
+
+/* The vendor opcodes list.  */
+const struct riscv_vendor_opcode riscv_vendor_list[] =
+{
+  /* Vendor T-HEAD.  */
+  {"xtheadc", vendor_thead_opcodes},
+  {NULL, NULL},
+};
+