[Mesa-dev] [PATCH 21/22] i965: Setup glsl uniforms by index rather than name matching

[Alejandro Piñeiro]

From: Neil Roberts <nroberts at igalia.com>

Previously when setting up a uniform it would try to walk the uniform
storage slots and find one that matches the name of the given
variable. However, each variable already has a location which is an
index into the UniformStorage array so we can just directly jump to
the right slot. Some of the variables take up more than one slot so we
still need to calculate how many it uses.

The main reason to do this is to support ARB_gl_spirv because in that
case the uniforms don’t have names so the previous approach won’t
work.
---
 src/mesa/drivers/dri/i965/brw_nir_uniforms.cpp | 50 +++++++++++++++++++-------
 1 file changed, 37 insertions(+), 13 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_nir_uniforms.cpp b/src/mesa/drivers/dri/i965/brw_nir_uniforms.cpp
index 62b2951432a..cb5e07f74ba 100644
--- a/src/mesa/drivers/dri/i965/brw_nir_uniforms.cpp
+++ b/src/mesa/drivers/dri/i965/brw_nir_uniforms.cpp
@@ -118,35 +118,59 @@ brw_setup_image_uniform_values(gl_shader_stage stage,
    }
 }
 
+static unsigned
+count_uniform_storage_slots(const struct glsl_type *type)
+{
+   /* gl_uniform_storage can cope with one level of array, so if the
+    * type is a composite type or an array where each element occupies
+    * more than one slot than we need to recursively process it.
+    */
+   if (glsl_type_is_struct(type)) {
+      unsigned location_count = 0;
+
+      for (unsigned i = 0; i < glsl_get_length(type); i++) {
+         const struct glsl_type *field_type = glsl_get_struct_field(type, i);
+
+         location_count += count_uniform_storage_slots(field_type);
+      }
+
+      return location_count;
+   }
+
+   if (glsl_type_is_array(type)) {
+      const struct glsl_type *element_type = glsl_get_array_element(type);
+
+      if (glsl_type_is_array(element_type) ||
+          glsl_type_is_struct(element_type)) {
+         unsigned element_count = count_uniform_storage_slots(element_type);
+         return element_count * glsl_get_length(type);
+      }
+   }
+
+   return 1;
+}
+
 static void
 brw_nir_setup_glsl_uniform(gl_shader_stage stage, nir_variable *var,
                            const struct gl_program *prog,
                            struct brw_stage_prog_data *stage_prog_data,
                            bool is_scalar)
 {
-   int namelen = strlen(var->name);
-
    /* The data for our (non-builtin) uniforms is stored in a series of
     * gl_uniform_storage structs for each subcomponent that
     * glGetUniformLocation() could name.  We know it's been set up in the same
-    * order we'd walk the type, so walk the list of storage and find anything
-    * with our name, or the prefix of a component that starts with our name.
+    * order we'd walk the type, so walk the list of storage that matches the
+    * range of slots covered by this variable.
     */
    unsigned uniform_index = var->data.driver_location / 4;
-   for (unsigned u = 0; u < prog->sh.data->NumUniformStorage; u++) {
+   unsigned num_slots = count_uniform_storage_slots(var->type);
+   for (unsigned u = 0; u < num_slots; u++) {
       struct gl_uniform_storage *storage =
-         &prog->sh.data->UniformStorage[u];
+         &prog->sh.data->UniformStorage[var->data.location + u];
 
       if (storage->builtin || storage->type->is_sampler())
          continue;
 
-      if (strncmp(var->name, storage->name, namelen) != 0 ||
-          (storage->name[namelen] != 0 &&
-           storage->name[namelen] != '.' &&
-           storage->name[namelen] != '[')) {
-         continue;
-      }
-
       if (storage->type->is_image()) {
          brw_setup_image_uniform_values(stage, stage_prog_data,
                                         uniform_index, storage);
-- 
2.14.1