Re: [Qemu-devel] [PATCH v2 8/8] target/s390x: Fix risbg handling

[Aurelien Jarno]

On 2017-07-01 13:26, Richard Henderson wrote:
> The rotation is to the left, but extract shifts to the right.
> The computation of the extract parameters needs adjusting.
> 
> For the entry condition, simplify
> 
>       64 - rot + len <= 64
>       -rot + len <= 0
>       len <= rot
> 
> Reported-by: David Hildenbrand <address@hidden>
> Suggested-by: Aurelien Jarno <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  target/s390x/translate.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/target/s390x/translate.c b/target/s390x/translate.c
> index 1f0c401..89b2ea5 100644
> --- a/target/s390x/translate.c
> +++ b/target/s390x/translate.c
> @@ -3472,8 +3472,8 @@ static ExitStatus op_risbg(DisasContext *s, DisasOps *o)
>      }
>  
>      /* In some cases we can implement this with extract.  */
> -    if (imask == 0 && pos == 0 && len > 0 && rot + len <= 64) {
> -        tcg_gen_extract_i64(o->out, o->in2, rot, len);
> +    if (imask == 0 && pos == 0 && len > 0 && len <= rot) {
> +        tcg_gen_extract_i64(o->out, o->in2, 64 - rot, len);
>          return NO_EXIT;
>      }

Reviewed-by: Aurelien Jarno <address@hidden>


-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
address@hidden                 http://www.aurel32.net