anv: Compact render targets

Previously, we would always emit all of the render targets in the subpass.
This commit changes it so that we compact render targets just like we do
with other resources.  Render targets are represented in the surface map by
using a descriptor set index of UINT16_MAX.

src/intel/vulkan/anv_pipeline.c

@@ -599,9 +599,6 @@ anv_pipeline_compile_fs(struct anv_pipeline *pipeline,
 
    populate_wm_prog_key(&pipeline->device->info, info, extra, &key);
 
-   if (pipeline->use_repclear)
-      key.nr_color_regions = 1;
-
    if (module->size > 0) {
       anv_hash_shader(sha1, &key, sizeof(key), module, entrypoint, spec_info);
       kernel = anv_pipeline_cache_search(cache, sha1, &stage_prog_data, &map);
@@ -613,7 +610,7 @@ anv_pipeline_compile_fs(struct anv_pipeline *pipeline,
       struct anv_pipeline_binding sampler_to_descriptor[256];
 
       map = (struct anv_pipeline_bind_map) {
-         .surface_to_descriptor = surface_to_descriptor,
+         .surface_to_descriptor = surface_to_descriptor + 8,
          .sampler_to_descriptor = sampler_to_descriptor
       };
 
@@ -623,6 +620,8 @@ anv_pipeline_compile_fs(struct anv_pipeline *pipeline,
       if (nir == NULL)
          return vk_error(VK_ERROR_OUT_OF_HOST_MEMORY);
 
+      unsigned num_rts = 0;
+      struct anv_pipeline_binding rt_bindings[8];
       nir_function_impl *impl = nir_shader_get_entrypoint(nir)->impl;
       nir_foreach_variable_safe(var, &nir->outputs) {
          if (var->data.location < FRAG_RESULT_DATA0)
@@ -630,13 +629,52 @@ anv_pipeline_compile_fs(struct anv_pipeline *pipeline,
 
          unsigned rt = var->data.location - FRAG_RESULT_DATA0;
          if (rt >= key.nr_color_regions) {
+            /* Out-of-bounds, throw it away */
             var->data.mode = nir_var_local;
             exec_node_remove(&var->node);
             exec_list_push_tail(&impl->locals, &var->node);
+            continue;
          }
+
+         /* Give it a new, compacted, location */
+         var->data.location = FRAG_RESULT_DATA0 + num_rts;
+
+         unsigned array_len =
+            glsl_type_is_array(var->type) ? glsl_get_length(var->type) : 1;
+         assert(num_rts + array_len <= 8);
+
+         for (unsigned i = 0; i < array_len; i++) {
+            rt_bindings[num_rts] = (struct anv_pipeline_binding) {
+               .set = ANV_DESCRIPTOR_SET_COLOR_ATTACHMENTS,
+               .offset = rt + i,
+            };
+         }
+
+         num_rts += array_len;
       }
 
-      anv_fill_binding_table(&prog_data.base, MAX_RTS);
+      if (pipeline->use_repclear) {
+         assert(num_rts == 1);
+         key.nr_color_regions = 1;
+      }
+
+      if (num_rts == 0) {
+         /* If we have no render targets, we need a null render target */
+         rt_bindings[0] = (struct anv_pipeline_binding) {
+            .set = ANV_DESCRIPTOR_SET_COLOR_ATTACHMENTS,
+            .offset = UINT16_MAX,
+         };
+         num_rts = 1;
+      }
+
+      assert(num_rts <= 8);
+      map.surface_to_descriptor -= num_rts;
+      map.surface_count += num_rts;
+      assert(map.surface_count <= 256);
+      memcpy(map.surface_to_descriptor, rt_bindings,
+             num_rts * sizeof(*rt_bindings));
+
+      anv_fill_binding_table(&prog_data.base, num_rts);
 
       void *mem_ctx = ralloc_context(NULL);