Re: [PATCH v6 20/21] target/riscv: Add MAX_INSN_LEN and insn_len

[Alistair Francis]

On Fri, Aug 19, 2022 at 1:42 PM Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> These will be useful in properly ending the TB.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/translate.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> index 38666ddc91..a719aa6e63 100644
> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -1022,6 +1022,14 @@ static uint32_t opcode_at(DisasContextBase *dcbase, 
> target_ulong pc)
>  /* Include decoders for factored-out extensions */
>  #include "decode-XVentanaCondOps.c.inc"
>
> +/* The specification allows for longer insns, but not supported by qemu. */
> +#define MAX_INSN_LEN  4
> +
> +static inline int insn_len(uint16_t first_word)
> +{
> +    return (first_word & 3) == 3 ? 4 : 2;
> +}
> +
>  static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t 
> opcode)
>  {
>      /*
> @@ -1037,7 +1045,7 @@ static void decode_opc(CPURISCVState *env, DisasContext 
> *ctx, uint16_t opcode)
>      };
>
>      /* Check for compressed insn */
> -    if (extract16(opcode, 0, 2) != 3) {
> +    if (insn_len(opcode) == 2) {
>          if (!has_ext(ctx, RVC)) {
>              gen_exception_illegal(ctx);
>          } else {
> --
> 2.34.1
>
>