[Mesa-dev] [PATCH 01/18] nir/linker: handle uniforms without explicit location

[Alejandro Piñeiro]

ARB_gl_spirv points that uniforms in general need explicit
location. But there are still some cases of uniforms without location,
like for example uniform atomic counters. Those doesn't have a
location from the OpenGL point of view (they are identified with a
binding), but Mesa internally assigns it a location.

Signed-off-by: Eduardo Lima <elima at igalia.com>
Signed-off-by: Alejandro Piñeiro <apinheiro at igalia.com>
Signed-off-by: Neil Roberts <nroberts at igalia.com>
---

The @FIXME included on the patch below is solved with the follow-up
path "nir/linker: use empty block info to assign uniform locations",
so perhaps it makes sense to just squash both patches. I don't have a
strong opinion on that, but I think that it would be easier to review
as splitted patches.


 src/compiler/glsl/gl_nir_link_uniforms.c | 61 ++++++++++++++++++++++++++++++--
 1 file changed, 59 insertions(+), 2 deletions(-)

diff --git a/src/compiler/glsl/gl_nir_link_uniforms.c b/src/compiler/glsl/gl_nir_link_uniforms.c
index c6961fbb6ca..388c1ab63fc 100644
--- a/src/compiler/glsl/gl_nir_link_uniforms.c
+++ b/src/compiler/glsl/gl_nir_link_uniforms.c
@@ -36,6 +36,8 @@
  * normal uniforms as mandatory, and so on).
  */
 
+#define UNMAPPED_UNIFORM_LOC ~0u
+
 static void
 nir_setup_uniform_remap_tables(struct gl_context *ctx,
                                struct gl_shader_program *prog)
@@ -58,8 +60,59 @@ nir_setup_uniform_remap_tables(struct gl_context *ctx,
    for (unsigned i = 0; i < prog->data->NumUniformStorage; i++) {
       struct gl_uniform_storage *uniform = &prog->data->UniformStorage[i];
 
+      if (prog->data->UniformStorage[i].remap_location == UNMAPPED_UNIFORM_LOC)
+         continue;
+
+      /* How many new entries for this uniform? */
+      const unsigned entries = MAX2(1, uniform->array_elements);
+      unsigned num_slots = glsl_get_component_slots(uniform->type);
+
+      uniform->storage = &data[data_pos];
+
+      /* Set remap table entries point to correct gl_uniform_storage. */
+      for (unsigned j = 0; j < entries; j++) {
+         unsigned element_loc = uniform->remap_location + j;
+         prog->UniformRemapTable[element_loc] = uniform;
+
+         data_pos += num_slots;
+      }
+   }
+
+   /* Reserve locations for rest of the uniforms. */
+   for (unsigned i = 0; i < prog->data->NumUniformStorage; i++) {
+      struct gl_uniform_storage *uniform = &prog->data->UniformStorage[i];
+
+      if (uniform->is_shader_storage)
+         continue;
+
+      /* Built-in uniforms should not get any location. */
+      if (uniform->builtin)
+         continue;
+
+      /* Explicit ones have been set already. */
+      if (uniform->remap_location != UNMAPPED_UNIFORM_LOC)
+         continue;
+
       /* How many new entries for this uniform? */
       const unsigned entries = MAX2(1, uniform->array_elements);
+
+      /* @FIXME: By now, we add un-assigned uniform locations to the end of
+       * the uniform file. We need to keep track of empty locations and use
+       * them.
+       */
+      unsigned chosen_location = prog->NumUniformRemapTable;
+
+      /* resize remap table to fit new entries */
+      prog->UniformRemapTable =
+         reralloc(prog,
+                  prog->UniformRemapTable,
+                  struct gl_uniform_storage *,
+                  prog->NumUniformRemapTable + entries);
+      prog->NumUniformRemapTable += entries;
+
+      /* set the base location in remap table for the uniform */
+      uniform->remap_location = chosen_location;
+
       unsigned num_slots = glsl_get_component_slots(uniform->type);
 
       uniform->storage = &data[data_pos];
@@ -302,8 +355,12 @@ nir_link_uniform(struct gl_context *ctx,
       }
       uniform->active_shader_mask |= 1 << stage;
 
-      /* Uniform has an explicit location */
-      uniform->remap_location = location;
+      if (location >= 0) {
+         /* Uniform has an explicit location */
+         uniform->remap_location = location;
+      } else {
+         uniform->remap_location = UNMAPPED_UNIFORM_LOC;
+      }
 
       /* @FIXME: the initialization of the following will be done as we
        * implement support for their specific features, like SSBO, atomics,
-- 
2.14.1