On 01.07.2017 22:27, Richard Henderson wrote:
> On 06/25/2017 03:19 PM, Aurelien Jarno wrote:
>> On 2017-06-23 01:12, David Hildenbrand wrote:
>>> If we have for example: r3 contains 0x00000000ffffffff
>>> ec 33 3f bf 61 55 risbg %r3,%r3,63,191,97
>>>
>>> We want to rotate 33 to the left and only keep MSB bit 63 of that. So the
>>> result is then exactly 1 (we're reading the sign of the 32 bit value).
>>>
>>> Current code assumes that we can do that via an extract, which is not
>>> true (at least not that easy) and produces a 0.
>>
>> I think the mistake there is that the rotation is done to the left,
>> while in extract the "shift" is done to the right. The following patch
>> should be enough:
>>
>> --- a/target/s390x/translate.c
>> +++ b/target/s390x/translate.c
>> @@ -3441,8 +3441,8 @@ 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 && rot - len >= 0) {
>> + tcg_gen_extract_i64(o->out, o->in2, 64 - rot, len);
>> return NO_EXIT;
>
> Agreed. Included.
>
>
> r~
>
Was able to test it with your version and it works just fine!
Thanks!
--
Thanks,
David
