[Mesa-dev] [PATCH v2 11/11] i965: Add scalar GS input lowering code.

[Kristian Høgsberg]

On Mon, Oct 12, 2015 at 02:49:13PM -0700, Kenneth Graunke wrote:
> We really ought to compute the VUE map at link time and stash it, rather
> than recomputing it here, but with the mess of program structures I
> wasn't sure where to put it.  We can improve that later.

Yeah, this will work for now,

Reviewed-by: Kristian Høgsberg <krh at bitplanet.net>

> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/drivers/dri/i965/brw_nir.c | 44 ++++++++++++++++++++++++++++++++-----
>  1 file changed, 39 insertions(+), 5 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_nir.c b/src/mesa/drivers/dri/i965/brw_nir.c
> index 4f35d81..d550ea5 100644
> --- a/src/mesa/drivers/dri/i965/brw_nir.c
> +++ b/src/mesa/drivers/dri/i965/brw_nir.c
> @@ -56,7 +56,8 @@ remap_vs_attrs(nir_block *block, void *closure)
>  }
>  
>  static void
> -brw_nir_lower_inputs(nir_shader *nir, bool is_scalar)
> +brw_nir_lower_inputs(const struct brw_device_info *devinfo,
> +                     nir_shader *nir, bool is_scalar)
>  {
>     switch (nir->stage) {
>     case MESA_SHADER_VERTEX:
> @@ -90,11 +91,43 @@ brw_nir_lower_inputs(nir_shader *nir, bool is_scalar)
>           }
>        }
>        break;
> -   case MESA_SHADER_GEOMETRY:
> -      foreach_list_typed(nir_variable, var, node, &nir->inputs) {
> -         var->data.driver_location = var->data.location;
> +   case MESA_SHADER_GEOMETRY: {
> +      if (!is_scalar) {
> +         foreach_list_typed(nir_variable, var, node, &nir->inputs) {
> +            var->data.driver_location = var->data.location;
> +         }
> +      } else {
> +         /* The GLSL linker will have already matched up GS inputs and
> +          * the outputs of prior stages.  The driver does extend VS outputs
> +          * in some cases, but only for legacy OpenGL or Gen4-5 hardware,
> +          * neither of which offer geometry shader support.  So we can
> +          * safely ignore that.
> +          *
> +          * For SSO pipelines, we use a fixed VUE map layout based on variable
> +          * locations, so we can rely on rendezvous-by-location to make this
> +          * work.
> +          *
> +          * However, we need to ignore VARYING_SLOT_PRIMITIVE_ID, as it's not
> +          * written by previous stages and shows up via payload magic.
> +          */
> +         struct brw_vue_map input_vue_map;
> +         GLbitfield64 inputs_read =
> +            nir->info.inputs_read & ~VARYING_BIT_PRIMITIVE_ID;
> +         brw_compute_vue_map(devinfo, &input_vue_map, inputs_read,
> +                             nir->info.separate_shader);
> +
> +         /* Start with the slot for the variable's base. */
> +         foreach_list_typed(nir_variable, var, node, &nir->inputs) {
> +            assert(input_vue_map.varying_to_slot[var->data.location] != -1);
> +            var->data.driver_location =
> +               input_vue_map.varying_to_slot[var->data.location];
> +         }
> +
> +         /* Inputs are stored in vec4 slots, so use type_size_vec4(). */
> +         nir_lower_io(nir, nir_var_shader_in, type_size_vec4);
>        }
>        break;
> +   }
>     case MESA_SHADER_FRAGMENT:
>        nir_assign_var_locations(&nir->inputs, &nir->num_inputs,
>                                 is_scalar ? type_size_scalar : type_size_vec4);
> @@ -166,6 +199,7 @@ brw_create_nir(struct brw_context *brw,
>                 bool is_scalar)
>  {
>     struct gl_context *ctx = &brw->ctx;
> +   const struct brw_device_info *devinfo = brw->intelScreen->devinfo;
>     const nir_shader_compiler_options *options =
>        ctx->Const.ShaderCompilerOptions[stage].NirOptions;
>     static const nir_lower_tex_options tex_options = {
> @@ -209,7 +243,7 @@ brw_create_nir(struct brw_context *brw,
>     /* Get rid of split copies */
>     nir_optimize(nir, is_scalar);
>  
> -   brw_nir_lower_inputs(nir, is_scalar);
> +   brw_nir_lower_inputs(devinfo, nir, is_scalar);
>     brw_nir_lower_outputs(nir, is_scalar);
>     nir_assign_var_locations(&nir->uniforms,
>                              &nir->num_uniforms,
> -- 
> 2.6.1
> 
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