[Mesa-dev] [PATCH] glsl/linker: properly fix output variable overlap check

[Kenneth Graunke]

On Wednesday, September 20, 2017 12:58:36 PM PDT Nicolai Hähnle wrote:
> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102904
> Fixes: 15cae12804e ("glsl/linker: fix output variable overlap check")
> ---
>  src/compiler/glsl/linker.cpp | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
> index ddd8301a739..71312b6a40d 100644
> --- a/src/compiler/glsl/linker.cpp
> +++ b/src/compiler/glsl/linker.cpp
> @@ -2880,39 +2880,45 @@ assign_attribute_or_color_locations(void *mem_ctx,
>                          if (assigned_component_mask & component_mask) {
>                             linker_error(prog, "overlapping component is "
>                                          "assigned to %ss %s and %s "
>                                          "(component=%d)\n",
>                                          string, assigned[i]->name, var->name,
>                                          var->data.location_frac);
>                             return false;
>                          }
>                       }
>                    }
> -
> -                  /* At most one variable per fragment output component should
> -                   * reach this. */
> -                  assert(assigned_attr < ARRAY_SIZE(assigned));
> -                  assigned[assigned_attr] = var;
> -                  assigned_attr++;
>                 } else if (target_index == MESA_SHADER_FRAGMENT ||
>                            (prog->IsES && prog->data->Version >= 300)) {
>                    linker_error(prog, "overlapping location is assigned "
>                                 "to %s `%s' %d %d %d\n", string, var->name,
>                                 used_locations, use_mask, attr);
>                    return false;
>                 } else {
>                    linker_warning(prog, "overlapping location is assigned "
>                                   "to %s `%s' %d %d %d\n", string, var->name,
>                                   used_locations, use_mask, attr);
>                 }
>              }
>  
> +            if (target_index == MESA_SHADER_FRAGMENT && !prog->IsES) {
> +               /* Only track assigned variables for non-ES fragment shaders
> +                * to avoid overflowing the array.
> +                *
> +                * At most one variable per fragment output component should
> +                * reach this.
> +                */
> +               assert(assigned_attr < ARRAY_SIZE(assigned));
> +               assigned[assigned_attr] = var;
> +               assigned_attr++;
> +            }
> +
>              used_locations |= (use_mask << attr);
>  
>              /* From the GL 4.5 core spec, section 11.1.1 (Vertex Attributes):
>               *
>               * "A program with more than the value of MAX_VERTEX_ATTRIBS
>               *  active attribute variables may fail to link, unless
>               *  device-dependent optimizations are able to make the program
>               *  fit within available hardware resources. For the purposes
>               *  of this test, attribute variables of the type dvec3, dvec4,
>               *  dmat2x3, dmat2x4, dmat3, dmat3x4, dmat4x3, and dmat4 may
> 

Thanks Nicolai!

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
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