Re: [PATCH v2 11/18] target/riscv/cpu: add misa_ext_infos[]

[Andrew Jones]

On Tue, Jun 13, 2023 at 05:58:50PM -0300, Daniel Henrique Barboza wrote:
> Next patch will add KVM specific user properties for both MISA and
> multi-letter extensions. For MISA extensions we want to make use of what
> is already available in misa_ext_cfgs[] to avoid code repetition.
> 
> The new misa_ext_infos[] array will hold name and description for each
> MISA extension that misa_ext_cfgs[] is declaring. We'll then use this
> new array in KVM code to avoid duplicating strings.
> 
> There's nothing holding us back from doing the same with multi-letter
> extensions. For now doing just with MISA extensions is enough.
> 
> Suggested-by: Andrew Jones <ajones@ventanamicro.com>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  target/riscv/cpu.c | 44 ++++++++++++++++++--------------------------
>  target/riscv/cpu.h | 22 +++++++++++++++++++++-
>  2 files changed, 39 insertions(+), 27 deletions(-)
> 
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 0b25d53bbe..edaf052f25 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -1562,33 +1562,25 @@ static void cpu_get_misa_ext_cfg(Object *obj, Visitor 
> *v, const char *name,
>      visit_type_bool(v, name, &value, errp);
>  }
>  
> +#define MISA_CFG(_bit, _enabled) \
> +    {.name = misa_ext_infos[_bit].name, \

Maybe just misa_ext_info[] for the name? 'infos' sounds odd to me.

> +     .description = misa_ext_infos[_bit].description, \
> +     .misa_bit = _bit, .enabled = _enabled}
> +
>  static const RISCVCPUMisaExtConfig misa_ext_cfgs[] = {
> -    {.name = "a", .description = "Atomic instructions",
> -     .misa_bit = RVA, .enabled = true},
> -    {.name = "c", .description = "Compressed instructions",
> -     .misa_bit = RVC, .enabled = true},
> -    {.name = "d", .description = "Double-precision float point",
> -     .misa_bit = RVD, .enabled = true},
> -    {.name = "f", .description = "Single-precision float point",
> -     .misa_bit = RVF, .enabled = true},
> -    {.name = "i", .description = "Base integer instruction set",
> -     .misa_bit = RVI, .enabled = true},
> -    {.name = "e", .description = "Base integer instruction set (embedded)",
> -     .misa_bit = RVE, .enabled = false},
> -    {.name = "m", .description = "Integer multiplication and division",
> -     .misa_bit = RVM, .enabled = true},
> -    {.name = "s", .description = "Supervisor-level instructions",
> -     .misa_bit = RVS, .enabled = true},
> -    {.name = "u", .description = "User-level instructions",
> -     .misa_bit = RVU, .enabled = true},
> -    {.name = "h", .description = "Hypervisor",
> -     .misa_bit = RVH, .enabled = true},
> -    {.name = "x-j", .description = "Dynamic translated languages",
> -     .misa_bit = RVJ, .enabled = false},
> -    {.name = "v", .description = "Vector operations",
> -     .misa_bit = RVV, .enabled = false},
> -    {.name = "g", .description = "General purpose (IMAFD_Zicsr_Zifencei)",
> -     .misa_bit = RVG, .enabled = false},
> +    MISA_CFG(RVA, true),
> +    MISA_CFG(RVC, true),
> +    MISA_CFG(RVD, true),
> +    MISA_CFG(RVF, true),
> +    MISA_CFG(RVI, true),
> +    MISA_CFG(RVE, false),
> +    MISA_CFG(RVM, true),
> +    MISA_CFG(RVS, true),
> +    MISA_CFG(RVU, true),
> +    MISA_CFG(RVH, true),
> +    MISA_CFG(RVJ, false),
> +    MISA_CFG(RVV, false),
> +    MISA_CFG(RVG, false),
>  };
>  
>  static void riscv_cpu_add_misa_properties(Object *cpu_obj)
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index e3e08d315f..6d2acea478 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -41,7 +41,7 @@
>  
>  #define RV(x) ((target_ulong)1 << (x - 'A'))
>  
> -/* Consider updating misa_ext_cfgs[] when adding new MISA bits here */
> +/* Consider updating misa_ext_infos[] when adding new MISA bits here */

Both arrays (_cfgs and _info) need consideration, right?

>  #define RVI RV('I')
>  #define RVE RV('E') /* E and I are mutually exclusive */
>  #define RVM RV('M')
> @@ -56,6 +56,26 @@
>  #define RVJ RV('J')
>  #define RVG RV('G')
>  
> +typedef struct misa_ext_info {
> +    const char *name;
> +    const char *description;
> +} MISAExtInfo;
> +
> +static const MISAExtInfo misa_ext_infos[] = {
> +    [RVA] = {"a", "Atomic instructions"},
> +    [RVC] = {"c", "Compressed instructions"},
> +    [RVD] = {"d", "Double-precision float point"},
> +    [RVF] = {"f", "Single-precision float point"},
> +    [RVI] = {"i", "Base integer instruction set"},
> +    [RVE] = {"e", "Base integer instruction set (embedded)"},
> +    [RVM] = {"m", "Integer multiplication and division"},
> +    [RVS] = {"s", "Supervisor-level instructions"},
> +    [RVU] = {"u", "User-level instructions"},
> +    [RVH] = {"h", "Hypervisor"},
> +    [RVJ] = {"x-j", "Dynamic translated languages"},
> +    [RVV] = {"v", "Vector operations"},
> +    [RVG] = {"g", "General purpose (IMAFD_Zicsr_Zifencei)"},
> +};

I'd export this array from target/riscv/cpu.c, rather than having each
source file that includes this header get its own copy.

Thanks,
drew