[Mesa-dev] [PATCH 2/3] mesa: build up a mask of active shader stages in a pipeline

[Timothy Arceri]

On Mon, 2015-12-07 at 11:29 +0200, Tapani Pälli wrote:
> This will be used for validating SSO pipeline where all active stages
> in linked programs should be in use when rendering.
> 
> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
> ---
>  src/mesa/main/mtypes.h      |  2 ++
>  src/mesa/main/pipelineobj.c | 39
> +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+)
> 
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index fa7ead0..d5a22c9 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -2824,6 +2824,8 @@ struct gl_pipeline_object
>     GLboolean Validated;                 /**< Pipeline Validation
> status */
>  
>     GLchar *InfoLog;
> +
> +   uint8_t ActiveStages;                /**< Stages used,
> (glUseProgramStages) */
>  };
>  
>  /**
> diff --git a/src/mesa/main/pipelineobj.c
> b/src/mesa/main/pipelineobj.c
> index 6710d0d..c510ee8 100644
> --- a/src/mesa/main/pipelineobj.c
> +++ b/src/mesa/main/pipelineobj.c
> @@ -218,6 +218,43 @@ _mesa_reference_pipeline_object_(struct
> gl_context *ctx,
>     }
>  }
>  
> +static GLenum
> +shader_bit_from_shader_stage(gl_shader_stage stage)
> +{
> +   switch (stage) {
> +   case MESA_SHADER_VERTEX:
> +      return GL_VERTEX_SHADER_BIT;
> +   case MESA_SHADER_FRAGMENT:
> +      return GL_FRAGMENT_SHADER_BIT;
> +   case MESA_SHADER_GEOMETRY:
> +      return GL_GEOMETRY_SHADER_BIT;
> +   case MESA_SHADER_TESS_CTRL:
> +      return GL_TESS_CONTROL_SHADER_BIT;
> +   case MESA_SHADER_TESS_EVAL:
> +      return GL_TESS_EVALUATION_SHADER_BIT;
> +   case MESA_SHADER_COMPUTE:
> +      return GL_COMPUTE_SHADER_BIT;
> +   default:
> +      unreachable("bad value in
> _mesa_shader_bit_from_shader_stage()");
> +   }
> +}
> +
> +static void
> +update_active_pipeline_stages(struct gl_pipeline_object *pipe,
> +                              struct gl_shader_program *shProg,
> +                              GLbitfield stages)
> +{
> +   unsigned i;
> +   for (i = 0; i < MESA_SHADER_STAGES; i++) {
> +      if ((stages & shader_bit_from_shader_stage(i)) != 0) {
> +         if (shProg && shProg->ActiveStages & (1 << i))
> +            pipe->ActiveStages |= (1 << i);
> +         else
> +            pipe->ActiveStages &= ~(1 << i);
> +      }
> +   }

I think you could do most of the validation at this point which would
reduce the amount of work required during rendering. You also have
forgotten about GL_ALL_SHADER_BITS.

For example could you do something like this? 

Note: You would need to call this function after the
 _mesa_use_shader_program() calls.

unsigned i;
unsigned j;     

for (i = 0; i < MESA_SHADER_STAGES; i++) {
   if (!pipe->CurrentProgram[i]) {
      struct gl_shader_program *shProg = pipe->CurrentProgram[i];
      for (j = 0; j < MESA_SHADER_STAGES; j++) {
         if (!shProg->_LinkedShaders[j])
         continue;

         /* Make sure that any shader stage is also used in the
pipeline */
         if (shProg != pipe->CurrentProgram[j]) {
            pipe->ValidProgramUse = false;
            return;
         }
      }
   }

   pipe->ValidProgramUse = true;
}

> +}
> +
>  /**
>   * Bound program to severals stages of the pipeline
>   */
> @@ -311,6 +348,8 @@ _mesa_UseProgramStages(GLuint pipeline,
> GLbitfield stages, GLuint program)
>        }
>     }
>  
> +   update_active_pipeline_stages(pipe, shProg, stages);
> +
>     /* Enable individual stages from the program as requested by the
>      * application.  If there is no shader for a requested stage in
> the
>      * program, _mesa_use_shader_program will enable fixed-function
> processing