[PATCH v3 03/11] RISC-V: Implement Priority syntax parser for Function Multi-Versioning

[Kito Cheng]

This will make the target attribute able to accept 'priority' as well?
so I guess we need to make riscv_target_attr_parser able to
distinguish target and target_version? maybe add an extra argument to
riscv_target_attr_parser?

On Thu, Oct 24, 2024 at 3:12 PM Yangyu Chen <cyy@cyyself.name> wrote:
>
> This patch adds the priority syntax parser to support the Function
> Multi-Versioning (FMV) feature in RISC-V. This feature allows users to
> specify the priority of the function version in the attribute syntax.
>
> Chnages based on RISC-V C-API PR:
> https://github.com/riscv-non-isa/riscv-c-api-doc/pull/85
>
> gcc/ChangeLog:
>
>         * config/riscv/riscv-target-attr.cc
>         (riscv_target_attr_parser::handle_priority): New function.
>         (riscv_target_attr_parser::update_settings): Update priority
>         attribute.
>         (riscv_process_one_target_attr): Add const qualifier to arg_str
>         and split arg_str with ';'.
>         * config/riscv/riscv.opt: Add TargetVariable riscv_fmv_priority.
> ---
>  gcc/config/riscv/riscv-target-attr.cc | 35 +++++++++++++++++++++++++--
>  gcc/config/riscv/riscv.opt            |  3 +++
>  2 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/config/riscv/riscv-target-attr.cc b/gcc/config/riscv/riscv-target-attr.cc
> index 8ce9607b3c9..087fbae77b0 100644
> --- a/gcc/config/riscv/riscv-target-attr.cc
> +++ b/gcc/config/riscv/riscv-target-attr.cc
> @@ -39,16 +39,19 @@ public:
>      : m_found_arch_p (false)
>      , m_found_tune_p (false)
>      , m_found_cpu_p (false)
> +    , m_found_priority_p (false)
>      , m_subset_list (nullptr)
>      , m_loc (loc)
>      , m_cpu_info (nullptr)
>      , m_tune (nullptr)
> +    , m_priority (0)
>    {
>    }
>
>    bool handle_arch (const char *);
>    bool handle_cpu (const char *);
>    bool handle_tune (const char *);
> +  bool handle_priority (const char *);
>
>    void update_settings (struct gcc_options *opts) const;
>  private:
> @@ -58,10 +61,12 @@ private:
>    bool m_found_arch_p;
>    bool m_found_tune_p;
>    bool m_found_cpu_p;
> +  bool m_found_priority_p;
>    riscv_subset_list *m_subset_list;
>    location_t m_loc;
>    const  riscv_cpu_info *m_cpu_info;
>    const char *m_tune;
> +  int m_priority;
>  };
>  }
>
> @@ -80,7 +85,8 @@ struct riscv_attribute_info
>  static const struct riscv_attribute_info riscv_attributes[]
>    = {{"arch", &riscv_target_attr_parser::handle_arch},
>       {"cpu", &riscv_target_attr_parser::handle_cpu},
> -     {"tune", &riscv_target_attr_parser::handle_tune}};
> +     {"tune", &riscv_target_attr_parser::handle_tune},
> +     {"priority", &riscv_target_attr_parser::handle_priority}};
>
>  bool
>  riscv_target_attr_parser::parse_arch (const char *str)
> @@ -210,6 +216,22 @@ riscv_target_attr_parser::handle_tune (const char *str)
>    return true;
>  }
>
> +bool
> +riscv_target_attr_parser::handle_priority (const char *str)
> +{
> +  if (m_found_priority_p)
> +    error_at (m_loc, "%<target()%> attribute: priority appears more than once");
> +  m_found_priority_p = true;
> +
> +  if (sscanf (str, "%d", &m_priority) != 1)
> +    {
> +      error_at (m_loc, "%<target()%> attribute: invalid priority %qs", str);
> +      return false;
> +    }
> +
> +  return true;
> +}
> +
>  void
>  riscv_target_attr_parser::update_settings (struct gcc_options *opts) const
>  {
> @@ -236,13 +258,16 @@ riscv_target_attr_parser::update_settings (struct gcc_options *opts) const
>        if (m_cpu_info)
>         opts->x_riscv_tune_string = m_cpu_info->tune;
>      }
> +
> +  if (m_priority)
> +    opts->x_riscv_fmv_priority = m_priority;
>  }
>
>  /* Parse ARG_STR which contains the definition of one target attribute.
>     Show appropriate errors if any or return true if the attribute is valid.  */
>
>  static bool
> -riscv_process_one_target_attr (char *arg_str,
> +riscv_process_one_target_attr (const char *arg_str,
>                                location_t loc,
>                                riscv_target_attr_parser &attr_parser)
>  {
> @@ -271,6 +296,12 @@ riscv_process_one_target_attr (char *arg_str,
>
>    arg[0] = '\0';
>    ++arg;
> +
> +  /* Skip splitter ';' if it exists.  */
> +  char *splitter = strchr (arg, ';');
> +  if (splitter)
> +    splitter[0] = '\0';
> +
>    for (const auto &attr : riscv_attributes)
>      {
>        /* If the names don't match up, or the user has given an argument
> diff --git a/gcc/config/riscv/riscv.opt b/gcc/config/riscv/riscv.opt
> index 6360ed3984d..61def798ca0 100644
> --- a/gcc/config/riscv/riscv.opt
> +++ b/gcc/config/riscv/riscv.opt
> @@ -523,6 +523,9 @@ Mask(XSFVCP) Var(riscv_sifive_subext)
>
>  Mask(XSFCEASE) Var(riscv_sifive_subext)
>
> +TargetVariable
> +int riscv_fmv_priority = 0
> +
>  Enum
>  Name(isa_spec_class) Type(enum riscv_isa_spec_class)
>  Supported ISA specs (for use with the -misa-spec= option):
> --
> 2.45.2
>