src/intel/compiler/brw_interpolation_map.c

/*
 * Copyright © 2013 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "brw_compiler.h"
#include "compiler/nir/nir.h"

static char const *get_qual_name(int mode)
{
   switch (mode) {
      case INTERP_MODE_NONE:          return "none";
      case INTERP_MODE_FLAT:          return "flat";
      case INTERP_MODE_SMOOTH:        return "smooth";
      case INTERP_MODE_NOPERSPECTIVE: return "nopersp";
      default:                             return "???";
   }
}

static void
gen4_frag_prog_set_interp_modes(struct brw_wm_prog_data *prog_data,
                                struct brw_vue_map *vue_map,
                                unsigned location, unsigned slot_count,
                                enum glsl_interp_mode interp)
{
   for (unsigned k = 0; k < slot_count; k++) {
      unsigned slot = vue_map->varying_to_slot[location + k];
      if (slot != -1 && prog_data->interp_mode[slot] == INTERP_MODE_NONE) {
         prog_data->interp_mode[slot] = interp;

         if (prog_data->interp_mode[slot] == INTERP_MODE_FLAT) {
            prog_data->contains_flat_varying = true;
         } else if (prog_data->interp_mode[slot] == INTERP_MODE_NOPERSPECTIVE) {
            prog_data->contains_noperspective_varying = true;
         }
      }
   }
}

/* Set up interpolation modes for every element in the VUE */
void
brw_setup_vue_interpolation(struct brw_vue_map *vue_map, nir_shader *nir,
                            struct brw_wm_prog_data *prog_data)
{
   /* Initialise interp_mode. INTERP_MODE_NONE == 0 */
   memset(prog_data->interp_mode, 0, sizeof(prog_data->interp_mode));

   if (!vue_map)
      return;

   /* HPOS always wants noperspective. setting it up here allows
    * us to not need special handling in the SF program.
    */
   unsigned pos_slot = vue_map->varying_to_slot[VARYING_SLOT_POS];
   if (pos_slot != -1) {;
      prog_data->interp_mode[pos_slot] = INTERP_MODE_NOPERSPECTIVE;
      prog_data->contains_noperspective_varying = true;
   }

   nir_foreach_shader_in_variable(var, nir) {
      unsigned location = var->data.location;
      unsigned slot_count = glsl_count_attribute_slots(var->type, false);

      gen4_frag_prog_set_interp_modes(prog_data, vue_map, location, slot_count,
                                      var->data.interpolation);

      if (location == VARYING_SLOT_COL0 || location == VARYING_SLOT_COL1) {
         location = location + VARYING_SLOT_BFC0 - VARYING_SLOT_COL0;
         gen4_frag_prog_set_interp_modes(prog_data, vue_map, location,
                                         slot_count, var->data.interpolation);
      }
   }

   bool debug = false;
   if (debug) {
      fprintf(stderr, "VUE map:\n");
      for (int i = 0; i < vue_map->num_slots; i++) {
         int varying = vue_map->slot_to_varying[i];
         if (varying == -1) {
            fprintf(stderr, "%d: --\n", i);
            continue;
         }

         fprintf(stderr, "%d: %d %s ofs %d\n",
                 i, varying,
                 get_qual_name(prog_data->interp_mode[i]),
                 brw_vue_slot_to_offset(i));
      }
   }
}