[Mesa-dev] [PATCH v2 4/6] glsl/linker: don't fail non static used inputs without matching outputs

[Andres Gomez]

https://patchwork.freedesktop.org/series/56400/

On Thu, 2019-02-07 at 07:53 +1100, Timothy Arceri wrote:
> Before reviewing this can we get a piglit test for the following scenario
> 
> Two "program" objects say:
> 
> 1. vs->gs
> 2. fs
> 
> Where the interface between vs and gs has a used input that doesn't 
> exist in the vs. The test should fail validation, the idea being the 
> test would have failed on your v1 of this patch.
> 
> Thanks.
> 
> 
> On 7/2/19 2:58 am, Andres Gomez wrote:
> > If there is no Static Use of an input variable, the linker shouldn't
> > fail whenever there is no defined matching output variable in the
> > previous stage.
> > 
> >  From page 47 (page 51 of the PDF) of the GLSL 4.60 v.5 spec:
> > 
> >    " Only the input variables that are statically read need to be
> >      written by the previous stage; it is allowed to have superfluous
> >      declarations of input variables."
> > 
> > Now, we complete this exception whenever the input variable has an
> > explicit location. Previously, 18004c338f6 ("glsl: fail when a
> > shader's input var has not an equivalent out var in previous") took
> > care of the cases in which the input variable didn't have an explicit
> > location.
> > 
> > v2: do the location based interface matching check regardless on
> >      whehter it is a separable program or not (Ilia).
> > 
> > Cc: Timothy Arceri <tarceri at itsqueeze.com>
> > Cc: Iago Toral Quiroga <itoral at igalia.com>
> > Cc: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
> > Cc: Tapani Pälli <tapani.palli at intel.com>
> > Cc: Ian Romanick <ian.d.romanick at intel.com>
> > Cc: Ilia Mirkin <imirkin at alum.mit.edu>
> > Signed-off-by: Andres Gomez <agomez at igalia.com>
> > ---
> >   src/compiler/glsl/link_varyings.cpp | 16 ++++++++++++++--
> >   1 file changed, 14 insertions(+), 2 deletions(-)
> > 
> > diff --git a/src/compiler/glsl/link_varyings.cpp b/src/compiler/glsl/link_varyings.cpp
> > index e5f7d3e322a..36908d95263 100644
> > --- a/src/compiler/glsl/link_varyings.cpp
> > +++ b/src/compiler/glsl/link_varyings.cpp
> > @@ -808,8 +808,20 @@ cross_validate_outputs_to_inputs(struct gl_context *ctx,
> >   
> >                  output = output_explicit_locations[idx][input->data.location_frac].var;
> >   
> > -               if (output == NULL ||
> > -                   input->data.location != output->data.location) {
> > +               if (output == NULL) {
> > +                  /* A linker failure should only happen when there is no
> > +                   * output declaration and there is Static Use of the
> > +                   * declared input.
> > +                   */
> > +                  if (input->data.used) {
> > +                     linker_error(prog,
> > +                                  "%s shader input `%s' with explicit location "
> > +                                  "has no matching output\n",
> > +                                  _mesa_shader_stage_to_string(consumer->Stage),
> > +                                  input->name);
> > +                     break;
> > +                  }
> > +               } else if (input->data.location != output->data.location) {
> >                     linker_error(prog,
> >                                  "%s shader input `%s' with explicit location "
> >                                  "has no matching output\n",
> > 
-- 
Br,

Andres