[Mesa-dev] [PATCH 1/2] gallivm: allow negation of all integer types

[Zack Rusin]

----- Original Message -----
> Am 02.05.2013 03:13, schrieb Zack Rusin:
> > It's valid. Some shaders do the negation on unsigned and then
> > use the results in opcodes taking signed integers.
> > 
> > Signed-off-by: Zack Rusin <zackr at vmware.com>
> > ---
> >  src/gallium/auxiliary/gallivm/lp_bld_tgsi.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/gallium/auxiliary/gallivm/lp_bld_tgsi.c
> > b/src/gallium/auxiliary/gallivm/lp_bld_tgsi.c
> > index 7255d97..66ff14c 100644
> > --- a/src/gallium/auxiliary/gallivm/lp_bld_tgsi.c
> > +++ b/src/gallium/auxiliary/gallivm/lp_bld_tgsi.c
> > @@ -339,9 +339,9 @@ lp_build_emit_fetch(
> >           assert(0);
> >           break;
> >        case TGSI_TYPE_SIGNED:
> > +      case TGSI_TYPE_UNSIGNED:
> >           res = lp_build_negate( &bld_base->int_bld, res );
> >           break;
> > -      case TGSI_TYPE_UNSIGNED:
> >        case TGSI_TYPE_VOID:
> >        default:
> >           assert(0);
> > 
> 
> Hmm are you sure we don't just have some opcodes incorrectly classified?
> When I checked sm4 opcodes none of the unsigned ones seemed to have
> negation listed as valid (and I don't think we'd need it for glsl -
> seems a bit odd to allow negation there).

Yea, it's not ideal, but it's a bit more complicated. This particular issue is that we don't have imad instrunction and we're using umad to implement it, which is completely compliant but it means that we can see those negations on unsigned's. We could either mark umad as taking signed ints, add an imad instrunction or just allow negation on unsigned's, I picked the last because it was the least amount of code.

z