nir: Use a single list for all shader variables

Instead of having separate lists of variables, roughly sorted by mode,
use a single list for all shader-level NIR variables.  This makes a few
list walks a bit longer here and there but list walks aren't a very
common thing in NIR at all.  On the other hand, it makes a lot of things
like validation, printing, etc. way simpler.  Also, there are a number
of cases where we move variables from inputs/outputs to globals and this
makes it way easier because we no longer have to move them between
lists.  We only have to deal with that if moving them from the shader to
a nir_function_impl.

Reviewed-by: Rob Clark <robdclark@chromium.org>
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5966>

src/compiler/nir/nir.c

@@ -44,10 +44,7 @@ nir_shader_create(void *mem_ctx,
 {
    nir_shader *shader = rzalloc(mem_ctx, nir_shader);
 
-   exec_list_make_empty(&shader->uniforms);
-   exec_list_make_empty(&shader->inputs);
-   exec_list_make_empty(&shader->outputs);
-   exec_list_make_empty(&shader->shared);
+   exec_list_make_empty(&shader->variables);
 
    shader->options = options;
 
@@ -59,8 +56,6 @@ nir_shader_create(void *mem_ctx,
    }
 
    exec_list_make_empty(&shader->functions);
-   exec_list_make_empty(&shader->globals);
-   exec_list_make_empty(&shader->system_values);
 
    shader->num_inputs = 0;
    shader->num_outputs = 0;
@@ -104,56 +99,38 @@ nir_reg_remove(nir_register *reg)
    exec_node_remove(&reg->node);
 }
 
-struct exec_list *
-nir_variable_list_for_mode(nir_shader *shader, nir_variable_mode mode)
-{
-   switch (mode) {
-   case nir_var_function_temp:
-      assert(!"nir_shader_add_variable cannot be used for local variables");
-      return NULL;
-
-   case nir_var_shader_temp:
-      return &shader->globals;
-
-   case nir_var_shader_in:
-      return &shader->inputs;
-
-   case nir_var_shader_out:
-      return &shader->outputs;
-
-   case nir_var_uniform:
-   case nir_var_mem_ubo:
-   case nir_var_mem_ssbo:
-      return &shader->uniforms;
-
-   case nir_var_mem_shared:
-      assert(gl_shader_stage_is_compute(shader->info.stage));
-      return &shader->shared;
-
-   case nir_var_mem_global:
-      assert(!"nir_shader_add_variable cannot be used for global memory");
-      return NULL;
-
-   case nir_var_system_value:
-      return &shader->system_values;
-
-   case nir_var_mem_push_const:
-      assert(!"nir_var_push_constant is not supposed to be used for variables");
-      return NULL;
-
-   default:
-      assert(!"invalid mode");
-      return NULL;
-   }
-}
-
 void
 nir_shader_add_variable(nir_shader *shader, nir_variable *var)
 {
-   struct exec_list *var_list =
-      nir_variable_list_for_mode(shader, var->data.mode);
-   if (var_list)
-      exec_list_push_tail(var_list, &var->node);
+   switch (var->data.mode) {
+   case nir_var_function_temp:
+      assert(!"nir_shader_add_variable cannot be used for local variables");
+      return;
+
+   case nir_var_shader_temp:
+   case nir_var_shader_in:
+   case nir_var_shader_out:
+   case nir_var_uniform:
+   case nir_var_mem_ubo:
+   case nir_var_mem_ssbo:
+   case nir_var_mem_shared:
+   case nir_var_system_value:
+      break;
+
+   case nir_var_mem_global:
+      assert(!"nir_shader_add_variable cannot be used for global memory");
+      return;
+
+   case nir_var_mem_push_const:
+      assert(!"nir_var_push_constant is not supposed to be used for variables");
+      return;
+
+   default:
+      assert(!"invalid mode");
+      return;
+   }
+
+   exec_list_push_tail(&shader->variables, &var->node);
 }
 
 nir_variable *
@@ -1820,35 +1797,12 @@ nir_index_instrs(nir_function_impl *impl)
    return index;
 }
 
-static void
-index_var_list(struct exec_list *list, unsigned *count)
-{
-   nir_foreach_variable(var, list)
-      var->index = (*count)++;
-}
-
 unsigned
 nir_shader_index_vars(nir_shader *shader, nir_variable_mode modes)
 {
    unsigned count = 0;
-   if (modes & nir_var_shader_temp)
-      index_var_list(&shader->globals, &count);
-
-   if (modes & nir_var_shader_in)
-      index_var_list(&shader->inputs, &count);
-
-   if (modes & nir_var_shader_out)
-      index_var_list(&shader->outputs, &count);
-
-   if (modes & (nir_var_uniform | nir_var_mem_ubo | nir_var_mem_ssbo))
-      index_var_list(&shader->uniforms, &count);
-
-   if (modes & nir_var_mem_shared)
-      index_var_list(&shader->shared, &count);
-
-   if (modes & nir_var_system_value)
-      index_var_list(&shader->system_values, &count);
-
+   nir_foreach_variable_with_modes(var, shader, modes)
+      var->index = count++;
    return count;
 }
 
@@ -1856,7 +1810,8 @@ unsigned
 nir_function_impl_index_vars(nir_function_impl *impl)
 {
    unsigned count = 0;
-   index_var_list(&impl->locals, &count);
+   nir_foreach_function_temp_variable(var, impl)
+      var->index = count++;
    return count;
 }