nir: use the same driver location for packed varyings

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/nir/nir.h

@@ -2312,8 +2312,8 @@ void nir_lower_io_to_temporaries(nir_shader *shader, nir_function *entrypoint,
 
 void nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint);
 
-void nir_assign_var_locations(struct exec_list *var_list,
+void nir_assign_var_locations(struct exec_list *var_list, unsigned *size,
-                              unsigned *size,
+                              unsigned base_offset,
                               int (*type_size)(const struct glsl_type *));
 
 void nir_lower_io(nir_shader *shader,

src/compiler/nir/nir_lower_io.c

@@ -43,10 +43,18 @@ struct lower_io_state {
 
 void
 nir_assign_var_locations(struct exec_list *var_list, unsigned *size,
+                         unsigned base_offset,
                          int (*type_size)(const struct glsl_type *))
 {
    unsigned location = 0;
 
+   /* There are 32 regular and 32 patch varyings allowed */
+   int locations[64][2];
+   for (unsigned i = 0; i < 64; i++) {
+      for (unsigned j = 0; j < 2; j++)
+         locations[i][j] = -1;
+   }
+
    nir_foreach_variable(var, var_list) {
       /*
        * UBO's have their own address spaces, so don't count them towards the
@@ -56,8 +64,24 @@ nir_assign_var_locations(struct exec_list *var_list, unsigned *size,
           var->interface_type != NULL)
          continue;
 
-      var->data.driver_location = location;
+      /* Make sure we give the same location to varyings packed with
-      location += type_size(var->type);
+       * ARB_enhanced_layouts.
+       */
+      int idx = var->data.location - base_offset;
+      if (base_offset && idx >= 0) {
+         assert(idx < ARRAY_SIZE(locations));
+
+         if (locations[idx][var->data.index] == -1) {
+            var->data.driver_location = location;
+            locations[idx][var->data.index] = location;
+            location += type_size(var->type);
+         } else {
+            var->data.driver_location = locations[idx][var->data.index];
+         }
+      } else {
+         var->data.driver_location = location;
+         location += type_size(var->type);
+      }
    }
 
    *size = location;

src/mesa/drivers/dri/i965/brw_nir.c

@@ -282,7 +282,8 @@ brw_nir_lower_tes_inputs(nir_shader *nir, const struct brw_vue_map *vue_map)
 void
 brw_nir_lower_fs_inputs(nir_shader *nir)
 {
-   nir_assign_var_locations(&nir->inputs, &nir->num_inputs, type_size_scalar);
+   nir_assign_var_locations(&nir->inputs, &nir->num_inputs, VARYING_SLOT_VAR0,
+                            type_size_scalar);
    nir_lower_io(nir, nir_var_shader_in, type_size_scalar);
 }
 
@@ -292,6 +293,7 @@ brw_nir_lower_vue_outputs(nir_shader *nir,
 {
    if (is_scalar) {
       nir_assign_var_locations(&nir->outputs, &nir->num_outputs,
+                               VARYING_SLOT_VAR0,
                                type_size_scalar);
       nir_lower_io(nir, nir_var_shader_out, type_size_scalar);
    } else {
@@ -330,14 +332,14 @@ void
 brw_nir_lower_fs_outputs(nir_shader *nir)
 {
    nir_assign_var_locations(&nir->outputs, &nir->num_outputs,
-                            type_size_scalar);
+                            FRAG_RESULT_DATA0, type_size_scalar);
    nir_lower_io(nir, nir_var_shader_out, type_size_scalar);
 }
 
 void
 brw_nir_lower_cs_shared(nir_shader *nir)
 {
-   nir_assign_var_locations(&nir->shared, &nir->num_shared,
+   nir_assign_var_locations(&nir->shared, &nir->num_shared, 0,
                             type_size_scalar_bytes);
    nir_lower_io(nir, nir_var_shared, type_size_scalar_bytes);
 }

src/mesa/drivers/dri/i965/brw_program.c

@@ -51,11 +51,11 @@ static void
 brw_nir_lower_uniforms(nir_shader *nir, bool is_scalar)
 {
    if (is_scalar) {
-      nir_assign_var_locations(&nir->uniforms, &nir->num_uniforms,
+      nir_assign_var_locations(&nir->uniforms, &nir->num_uniforms, 0,
                                type_size_scalar_bytes);
       nir_lower_io(nir, nir_var_uniform, type_size_scalar_bytes);
    } else {
-      nir_assign_var_locations(&nir->uniforms, &nir->num_uniforms,
+      nir_assign_var_locations(&nir->uniforms, &nir->num_uniforms, 0,
                                type_size_vec4_bytes);
       nir_lower_io(nir, nir_var_uniform, type_size_vec4_bytes);
    }

src/mesa/state_tracker/st_glsl_to_nir.cpp

@@ -308,16 +308,19 @@ st_finalize_nir(struct st_context *st, struct gl_program *prog, nir_shader *nir)
       sort_varyings(&nir->outputs);
       nir_assign_var_locations(&nir->outputs,
                                &nir->num_outputs,
+                               VARYING_SLOT_VAR0,
                                st_glsl_type_size);
       st_nir_fixup_varying_slots(st, &nir->outputs);
    } else if (nir->stage == MESA_SHADER_FRAGMENT) {
       sort_varyings(&nir->inputs);
       nir_assign_var_locations(&nir->inputs,
                                &nir->num_inputs,
+                               VARYING_SLOT_VAR0,
                                st_glsl_type_size);
       st_nir_fixup_varying_slots(st, &nir->inputs);
       nir_assign_var_locations(&nir->outputs,
                                &nir->num_outputs,
+                               FRAG_RESULT_DATA0,
                                st_glsl_type_size);
    } else {
       unreachable("invalid shader type for tgsi bypass\n");