diff mbox

[v2,8/8] target/s390x: Fix risbg handling

Message ID 20170701202600.14057-9-rth@twiddle.net (mailing list archive)
State New, archived
Headers show

Commit Message

Richard Henderson July 1, 2017, 8:26 p.m. UTC
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 <david@redhat.com>
Suggested-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 target/s390x/translate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Aurelien Jarno July 2, 2017, 1:18 p.m. UTC | #1
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 <david@redhat.com>
> Suggested-by: Aurelien Jarno <aurelien@aurel32.net>
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  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 <aurelien@aurel32.net>
diff mbox

Patch

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;
     }