Re: [PATCH 43/56] disas/riscv: Fix isa decoding of rev8

On Sun, 2026-08-09 at 15:35 -0700, Richard Henderson wrote:
> The encoding of rev8 is different for rv32 and rv64.
> 
> Cc: [email protected]
> Fixes: 02c1b569a15 ("disas/riscv: Add Zb[abcs] instructions")
> Signed-off-by: Richard Henderson <[email protected]>

Reviewed-by: Alistair Francis <[email protected]>

Alistair

> ---
>  disas/riscv.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/disas/riscv.c b/disas/riscv.c
> index 9442a6c115..4141741d79 100644
> --- a/disas/riscv.c
> +++ b/disas/riscv.c
> @@ -3292,8 +3292,16 @@ static const rv_opcode_data
> *decode_inst_opcode(rv_decode *dec, rv_isa isa)
>                  case 0b01100: op = rv_op_rori; break;
>                  case 0b01101:
>                      switch ((inst >> 20) & 0b1111111) {
> -                    case 0b0011000: op = rv_op_rev8; break;
> -                    case 0b0111000: op = rv_op_rev8; break;
> +                    case 0b0011000:
> +                        if (isa == rv32) {
> +                            op = rv_op_rev8;
> +                        }
> +                        break;
> +                    case 0b0111000:
> +                        if (isa == rv64) {
> +                            op = rv_op_rev8;
> +                        }
> +                        break;
>                      case 0b0000111: op = rv_op_brev8; break;
>                      }
>                      break;