glsl: don't lower builtins to mediump that don't allow it

[mesa.git] / src / compiler / glsl / gl_nir_linker.c

diff --git a/src/compiler/glsl/gl_nir_linker.c b/src/compiler/glsl/gl_nir_linker.c
index fb8b3e0c340967de9798aa65f86ced678cf73ba8..4a7a31629b825ea5e5fc402241dc68704533c82b 100644 (file)
--- a/src/compiler/glsl/gl_nir_linker.c
+++ b/src/compiler/glsl/gl_nir_linker.c
@@ -34,6 +34,38 @@
  * the counter-part glsl/linker.cpp
  */
 
+static bool
+can_remove_uniform(nir_variable *var)
+{
+   /* Section 2.11.6 (Uniform Variables) of the OpenGL ES 3.0.3 spec
+    * says:
+    *
+    *     "All members of a named uniform block declared with a shared or
+    *     std140 layout qualifier are considered active, even if they are not
+    *     referenced in any shader in the program. The uniform block itself is
+    *     also considered active, even if no member of the block is
+    *     referenced."
+    *
+    * Although the spec doesn't state it std430 layouts are expect to behave
+    * the same way. If the variable is in a uniform block with one of those
+    * layouts, do not eliminate it.
+    */
+   if (nir_variable_is_in_block(var) &&
+       (glsl_get_ifc_packing(var->interface_type) !=
+        GLSL_INTERFACE_PACKING_PACKED))
+      return false;
+
+   if (glsl_get_base_type(glsl_without_array(var->type)) ==
+       GLSL_TYPE_SUBROUTINE)
+      return false;
+
+   /* Uniform initializers could get used by another stage */
+   if (var->constant_initializer)
+      return false;
+
+   return true;
+}
+
 /**
  * Built-in / reserved GL variables names start with "gl_"
  */
@@ -255,8 +287,8 @@ add_shader_variable(const struct gl_context *ctx,
          }
          return true;
       }
-      /* fallthrough */
    }
+   /* fallthrough */
 
    default: {
       /* The ARB_program_interface_query spec says:
@@ -569,6 +601,14 @@ bool
 gl_nir_link_spirv(struct gl_context *ctx, struct gl_shader_program *prog,
                   const struct gl_nir_linker_options *options)
 {
+   for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
+      struct gl_linked_shader *shader = prog->_LinkedShaders[i];
+      if (shader) {
+         nir_remove_dead_variables(shader->Program->nir, nir_var_uniform,
+                                   &can_remove_uniform);
+      }
+   }
+
    if (!gl_nir_link_uniform_blocks(ctx, prog))
       return false;
 
@@ -622,6 +662,14 @@ check_image_resources(struct gl_context *ctx, struct gl_shader_program *prog)
 bool
 gl_nir_link_glsl(struct gl_context *ctx, struct gl_shader_program *prog)
 {
+   for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
+      struct gl_linked_shader *shader = prog->_LinkedShaders[i];
+      if (shader) {
+         nir_remove_dead_variables(shader->Program->nir, nir_var_uniform,
+                                   &can_remove_uniform);
+      }
+   }
+
    if (!gl_nir_link_uniforms(ctx, prog, true))
       return false;