Re: chacha20-s390 broken in 8.2.0 in TCG on s390x

[Michael Tokarev]

04.01.2024 01:51, Richard Henderson :
> On 1/4/24 01:37, Philippe Mathieu-Daudé wrote:
> > Finally changing the constraints on op_rotli_vec seems to fix it:
> >
> > ---
> > diff --git a/tcg/s390x/tcg-target.c.inc b/tcg/s390x/tcg-target.c.inc
> > index fbee43d3b0..b3456fe857 100644
> > --- a/tcg/s390x/tcg-target.c.inc
> > +++ b/tcg/s390x/tcg-target.c.inc
> > @@ -3264,13 +3264,13 @@ static TCGConstraintSetIndex 
> > tcg_target_op_def(TCGOpcode op)
> >       case INDEX_op_ld_vec:
> >       case INDEX_op_dupm_vec:
> > +    case INDEX_op_rotli_vec:
> >           return C_O1_I1(v, r);
> >       case INDEX_op_dup_vec:
> >           return C_O1_I1(v, vr);
> >       case INDEX_op_abs_vec:
> >       case INDEX_op_neg_vec:
> >       case INDEX_op_not_vec:
> > -    case INDEX_op_rotli_vec:
> >       case INDEX_op_sari_vec:
> >       case INDEX_op_shli_vec:
> >       case INDEX_op_shri_vec:
> >       case INDEX_op_s390_vuph_vec:
> >       case INDEX_op_s390_vupl_vec:
> >           return C_O1_I1(v, v);
>
> Definitely not correct, since VERLL requires a vector input to be rotated.
>
> > But I'm outside of my comfort zone so not really sure what I'm doing...
> > (I was inspired by the "the instruction verll only allows immediates up
> > to 32 bits." comment from
> > https://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg317099.html)
>
> That message is confused.  The immediate in VERLL is 12 bits (with only 6 bits ever used 
> for MO_64).  Dunno where "32 bits" comes from.

So, what do we have here in the end?
Should we fix this on qemu side?

This thread stopped quite some time ago, with problematic
instruction found but no solution..

Thanks,

/mjt