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

[Jose Fonseca]

----- Original Message -----
> ----- 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.

I don't oppose either.  Integer signedness has always been too loose for us to be pedantic about it here.

Jose