[RFC 1/4] RISC-V: Hypervisor ext: Treat as "Standard" extension

[Palmer Dabbelt]

On Thu, 16 Dec 2021 09:33:25 PST (-0800), Vineet Gupta wrote:
> gas currently fails for single-letter 'h' prefix in arch string.
>
> | riscv64-unknown-elf-as -march=rv64gh empty.s
> | Assembler messages:
> | Error: rv64gh: unknown prefixed ISA extension `h'
>
> It implements the "multi-letter" prefix for H-ext as recommended in
> ISA manual subsection "ISA Extension Naming Conventions". However given
> the discussions at [1] there seems to be no pressing need to keep version
> for the current H-ext since
>  - it will remain at 1.0
>  - any future Hypervisor extensions wull called "Sh*" or some such
>  - H was the original standard extension with its own MISA bit
>
> This patch thus relaxes the constraint and allows single letter prefix
> 'h'
>
> Note: To keep the binutils dejagnu failures same, I've fixed the
> testsuite files within the same patch. I can break it up if reviewers
> feel as such.
>
> [1] https://github.com/riscv/riscv-isa-manual/issues/781#issuecomment-983233088
>
> bfd/
> 	* elfxx-riscv.c (riscv_supported_std_ext): Add "h" entry.
> 	(riscv_supported_std_h_ext): Add "h" entry.
> 	(riscv_get_default_ext_version): Handle PRIV_SPEC_CLASS_DRAFT.
> 	(riscv_multi_subset_supports): Handle INSN_CLASS_H.
>
> gas/
> 	* testsuite/gas/riscv/march-fail-single-prefix-h.d: Deleted as
> 	single-letter prefix 'h' is now valid.
> 	* testsuite/gas/riscv/march-fail-single-prefix-l: Removed 'h'.
>
> include/
> 	* opcode/riscv.h (enum riscv_insn_class): Add INSN_CLASS_H.
>
> Signed-off-by: Vineet Gupta <vineetg@rivosinc.com>
> ---
>  bfd/elfxx-riscv.c                                    | 5 +++++
>  gas/testsuite/gas/riscv/march-fail-single-prefix-h.d | 3 ---
>  gas/testsuite/gas/riscv/march-fail-single-prefix.l   | 2 +-
>  include/opcode/riscv.h                               | 1 +
>  4 files changed, 7 insertions(+), 4 deletions(-)
>  delete mode 100644 gas/testsuite/gas/riscv/march-fail-single-prefix-h.d
>
> diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
> index 3bd41ff2b551..7d5ae5a4657d 100644
> --- a/bfd/elfxx-riscv.c
> +++ b/bfd/elfxx-riscv.c
> @@ -1173,6 +1173,7 @@ static struct riscv_supported_ext riscv_supported_std_ext[] =
>    {"t",		ISA_SPEC_CLASS_NONE, RISCV_UNKNOWN_VERSION, RISCV_UNKNOWN_VERSION, 0 },
>    {"p",		ISA_SPEC_CLASS_NONE, RISCV_UNKNOWN_VERSION, RISCV_UNKNOWN_VERSION, 0 },
>    {"v",		ISA_SPEC_CLASS_DRAFT,		1, 0, 0 },
> +  {"h",		PRIV_SPEC_CLASS_DRAFT,		1, 0, 0 },

According to 
<https://wiki.riscv.org/display/TECH/Recently+Ratified+Extensions>, this 
was ratified in November so we should be able to update this to 
something like PRIV_SPEC_CLASS_1P12 (the V stuff was also ratified, but 
that's a different issue).

>    {"n",		ISA_SPEC_CLASS_NONE, RISCV_UNKNOWN_VERSION, RISCV_UNKNOWN_VERSION, 0 },
>    {NULL, 0, 0, 0, 0}
>  };
> @@ -1232,6 +1233,7 @@ static struct riscv_supported_ext riscv_supported_std_s_ext[] =
>
>  static struct riscv_supported_ext riscv_supported_std_h_ext[] =
>  {
> +  {"h",                 PRIV_SPEC_CLASS_DRAFT,          1, 0, 0 },
>    {NULL, 0, 0, 0, 0}
>  };
>
> @@ -1531,6 +1533,7 @@ riscv_get_default_ext_version (enum riscv_spec_class *default_isa_spec,
>      {
>        if (strcmp (table[i].name, name) == 0
>  	  && (table[i].isa_spec_class == ISA_SPEC_CLASS_DRAFT
> +	      || table[i].isa_spec_class == PRIV_SPEC_CLASS_DRAFT
>  	      || table[i].isa_spec_class == *default_isa_spec))
>  	{
>  	  *major_version = table[i].major_version;
> @@ -2412,6 +2415,8 @@ riscv_multi_subset_supports (riscv_parse_subset_t *rps,
>  	      || riscv_subset_supports (rps, "zve64d")
>  	      || riscv_subset_supports (rps, "zve64f")
>  	      || riscv_subset_supports (rps, "zve32f"));
> +    case INSN_CLASS_H:
> +      return riscv_subset_supports (rps, "h");
>      default:
>        rps->error_handler
>          (_("internal: unreachable INSN_CLASS_*"));
> diff --git a/gas/testsuite/gas/riscv/march-fail-single-prefix-h.d b/gas/testsuite/gas/riscv/march-fail-single-prefix-h.d
> deleted file mode 100644
> index eb101bd71353..000000000000
> --- a/gas/testsuite/gas/riscv/march-fail-single-prefix-h.d
> +++ /dev/null
> @@ -1,3 +0,0 @@
> -#as: -march=rv32ih
> -#source: empty.s
> -#error_output: march-fail-single-prefix.l
> diff --git a/gas/testsuite/gas/riscv/march-fail-single-prefix.l b/gas/testsuite/gas/riscv/march-fail-single-prefix.l
> index 13942ed66642..e4418de69acb 100644
> --- a/gas/testsuite/gas/riscv/march-fail-single-prefix.l
> +++ b/gas/testsuite/gas/riscv/march-fail-single-prefix.l
> @@ -1,2 +1,2 @@
>  .*Assembler messages:
> -.*Error: .*unknown prefixed ISA extension `(s|h|z|x|zxm)'
> +.*Error: .*unknown prefixed ISA extension `(s|z|x|zxm)'
> diff --git a/include/opcode/riscv.h b/include/opcode/riscv.h
> index 14889972abce..2783bdecaae5 100644
> --- a/include/opcode/riscv.h
> +++ b/include/opcode/riscv.h
> @@ -387,6 +387,7 @@ enum riscv_insn_class
>    INSN_CLASS_ZKND_OR_ZKNE,
>    INSN_CLASS_V,
>    INSN_CLASS_ZVEF,
> +  INSN_CLASS_H,
>  };
>
>  /* This structure holds information for a particular instruction.  */

Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>

We can always deal with the draft/ratified stuff later, as there's a 
bunch of them.