[Mesa-stable] [Mesa-dev] [PATCH] glsl/linker: Link all out vars from a shader objects on a single stage

[Andres Gomez]

Vadym, should we also include this in the stable queues ?


On Mon, 2018-08-27 at 15:20 +0300, Vadym Shovkoplias wrote:
> From: "vadym.shovkoplias" <vadym.shovkoplias at globallogic.com>
> 
> During intra stage linking some out variables can be dropped because
> it is not used in a shader with the main function. But these out vars
> can be referenced on later stages which can lead to further linking
> errors.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105731
> Signed-off-by: Vadym Shovkoplias <vadym.shovkoplias at globallogic.com>
> ---
>  src/compiler/glsl/linker.cpp | 38 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
> index 3ce78fe642..3b0c01c316 100644
> --- a/src/compiler/glsl/linker.cpp
> +++ b/src/compiler/glsl/linker.cpp
> @@ -2187,6 +2187,41 @@ link_cs_input_layout_qualifiers(struct gl_shader_program *prog,
>     }
>  }
>  
> +/**
> + * Link all out variables on a single stage which are not
> + * directly used in a shader with the main function.
> + */
> +static void
> +link_output_variables(struct gl_linked_shader *linked_shader,
> +                      struct gl_shader **shader_list,
> +                      unsigned num_shaders)
> +{
> +   struct glsl_symbol_table *symbols = linked_shader->symbols;
> +
> +   for (unsigned i = 0; i < num_shaders; i++) {
> +
> +      /* Skip shader object with main function */
> +      if (shader_list[i]->symbols->get_function("main"))
> +         continue;
> +
> +      foreach_in_list (ir_instruction, ir, shader_list[i]->ir) {
> +
> +         if (ir->ir_type != ir_type_variable)
> +            continue;
> +
> +         ir_variable *const var = (ir_variable *) ir;
> +
> +         if (var->data.mode == ir_var_shader_out &&
> +               !symbols->get_variable(var->name)) {
> +            symbols->add_variable(var);
> +            linked_shader->ir->push_head(var);
> +         }
> +      }
> +   }
> +
> +   return;
> +}
> +
>  
>  /**
>   * Combine a group of shaders for a single stage to generate a linked shader
> @@ -2352,6 +2387,9 @@ link_intrastage_shaders(void *mem_ctx,
>        return NULL;
>     }
>  
> +   if (linked->Stage != MESA_SHADER_FRAGMENT)
> +      link_output_variables(linked, shader_list, num_shaders);
> +
>     /* Make a pass over all variable declarations to ensure that arrays with
>      * unspecified sizes have a size specified.  The size is inferred from the
>      * max_array_access field.
-- 
Br,

Andres