[Mesa-dev] [PATCH 097/133] nir/validate: Ensure that outputs are write-only and inputs are read-only

[Jason Ekstrand]

On Tue, Jan 6, 2015 at 1:46 PM, Chris Forbes <chrisf at ijw.co.nz> wrote:

> Worth pointing out that when tessellation gets ported to NIR, output
> reads are a real thing, and can't be lowered away like we do for other
> stages (they allow cross-invocation communication, so have to actually
> read back from the URB on i965)
>

Yuck!  In that case, we'll have to handle those somehow.  Cross that bridge
when we come to it?  For now, passes depend on outputs being write-only.


>
> On Wed, Jan 7, 2015 at 10:43 AM, Jason Ekstrand <jason at jlekstrand.net>
> wrote:
> >
> >
> > On Sun, Jan 4, 2015 at 8:48 PM, Connor Abbott <cwabbott0 at gmail.com>
> wrote:
> >>
> >> I'm not so sure how I feel about checking that outputs are write-only...
> >> eventually we'll want to do lower_input_reads in NIR itself, at which
> point
> >> we'll need to remove that part from the validator. At the same time,
> for now
> >> this is somewhat useful. I'm just not sure if it's worth it (making sure
> >> inputs are read-only definitely is, though).
> >
> >
> > Yes, we may want to do that lowering in NIR and I've already written the
> > pass.  It's lying around somewhere in my git tree.  However, the only
> > producers of NIR that we currently have are GLSL IR which already has the
> > pass, and TGSI which already has the outputs-are-write-only restriction.
> > For now, I like this bit of validation as it keeps us from breaking other
> > passes that depend on this.
> >
> > Do we want this in the end?  Absoltuely!  We do not want to deal with
> this
> > in nir_lower_variables.  I tried to but it's an absolute pain.  It's much
> > easier to just remove the copies.
> >
> >>
> >>
> >> On Tue, Dec 16, 2014 at 1:11 AM, Jason Ekstrand <jason at jlekstrand.net>
> >> wrote:
> >>>
> >>> ---
> >>>  src/glsl/nir/nir_validate.c | 23 +++++++++++++++++++++++
> >>>  1 file changed, 23 insertions(+)
> >>>
> >>> diff --git a/src/glsl/nir/nir_validate.c b/src/glsl/nir/nir_validate.c
> >>> index 80faa15..b8ef802 100644
> >>> --- a/src/glsl/nir/nir_validate.c
> >>> +++ b/src/glsl/nir/nir_validate.c
> >>> @@ -337,6 +337,29 @@ validate_intrinsic_instr(nir_intrinsic_instr
> *instr,
> >>> validate_state *state)
> >>>        validate_deref_var(instr->variables[i], state);
> >>>     }
> >>>
> >>> +   switch (instr->intrinsic) {
> >>> +   case nir_intrinsic_load_var_vec1:
> >>> +   case nir_intrinsic_load_var_vec2:
> >>> +   case nir_intrinsic_load_var_vec3:
> >>> +   case nir_intrinsic_load_var_vec4:
> >>> +      assert(instr->variables[0]->var->data.mode !=
> nir_var_shader_out);
> >>> +      break;
> >>> +   case nir_intrinsic_store_var_vec1:
> >>> +   case nir_intrinsic_store_var_vec2:
> >>> +   case nir_intrinsic_store_var_vec3:
> >>> +   case nir_intrinsic_store_var_vec4:
> >>> +      assert(instr->variables[0]->var->data.mode != nir_var_shader_in
> &&
> >>> +             instr->variables[0]->var->data.mode != nir_var_uniform);
> >>> +      break;
> >>> +   case nir_intrinsic_copy_var:
> >>> +      assert(instr->variables[0]->var->data.mode != nir_var_shader_in
> &&
> >>> +             instr->variables[0]->var->data.mode != nir_var_uniform);
> >>> +      assert(instr->variables[1]->var->data.mode !=
> nir_var_shader_out);
> >>> +      break;
> >>> +   default:
> >>> +      break;
> >>> +   }
> >>> +
> >>>     if (instr->has_predicate)
> >>>        validate_src(&instr->predicate, state);
> >>>  }
> >>> --
> >>> 2.2.0
> >>>
> >>> _______________________________________________
> >>> mesa-dev mailing list
> >>> mesa-dev at lists.freedesktop.org
> >>> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
> >>
> >>
> >
> >
> > _______________________________________________
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> >
>
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