On Wed, Mar 04, 2026 at 09:25:11PM +0800, Max Chou wrote:
> According to the Zvfbfa ISA spec (v0.1), improperly NaN-boxed
> f-register operands must substitute the BF16 canonical NaN instead of
> the FP16 canonical NaN for some vector floating-point instructions.
> 
> Reviewed-by: Daniel Henrique Barboza <[email protected]>
> Signed-off-by: Max Chou <[email protected]>
> ---
>  target/riscv/insn_trans/trans_rvv.c.inc | 18 +++++++++---------
>  target/riscv/translate.c                |  8 ++++++++
>  2 files changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/target/riscv/insn_trans/trans_rvv.c.inc 
> b/target/riscv/insn_trans/trans_rvv.c.inc
> index 4df9a40b44..03ae85796a 100644
> --- a/target/riscv/insn_trans/trans_rvv.c.inc
> +++ b/target/riscv/insn_trans/trans_rvv.c.inc
> @@ -2319,17 +2319,17 @@ GEN_OPIWI_NARROW_TRANS(vnclip_wi, IMM_ZX, vnclip_wx)
>   */
>  static void do_nanbox(DisasContext *s, TCGv_i64 out, TCGv_i64 in)
>  {
> -    switch (s->sew) {
> -    case 1:
> -        gen_check_nanbox_h(out, in);
> -        break;
> -    case 2:
> +    if (s->sew == MO_16) {
> +        if (s->altfmt) {
> +            gen_check_nanbox_h_bf16(out, in);
> +        } else {
> +            gen_check_nanbox_h(out, in);
> +        }
> +    } else if (s->sew == MO_32) {
>          gen_check_nanbox_s(out, in);
> -        break;
> -    case 3:
> +    } else if (s->sew == MO_64) {
>          tcg_gen_mov_i64(out, in);
> -        break;
> -    default:
> +    } else {
>          g_assert_not_reached();
>      }
>  }
> diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> index 89d4f6fe67..d9df6a35ca 100644
> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -214,6 +214,14 @@ static void gen_check_nanbox_h(TCGv_i64 out, TCGv_i64 in)
>      tcg_gen_movcond_i64(TCG_COND_GEU, out, in, t_max, in, t_nan);
>  }
>  
> +static void gen_check_nanbox_h_bf16(TCGv_i64 out, TCGv_i64 in)
> +{
> +    TCGv_i64 t_max = tcg_constant_i64(0xffffffffffff0000ull);
> +    TCGv_i64 t_nan = tcg_constant_i64(0xffffffffffff7fc0ull);
BF16 canonical NaN is 0x7fc0. Correct.

Reviewed-by: Chao Liu <[email protected]>

Best regards,
Chao Liu
> +
> +    tcg_gen_movcond_i64(TCG_COND_GEU, out, in, t_max, in, t_nan);
> +}
> +
>  static void gen_check_nanbox_s(TCGv_i64 out, TCGv_i64 in)
>  {
>      TCGv_i64 t_max = tcg_constant_i64(0xffffffff00000000ull);
> -- 
> 2.52.0
> 

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