mesa: glsl: add usage tracking for uniform vars

Unused uniforms are no longer included in the active uniforms list.

src/mesa/shader/prog_parameter.c

@@ -277,6 +277,26 @@ _mesa_add_uniform(struct gl_program_parameter_list *paramList,
 }
 
 
+/**
+ * Mark the named uniform as 'used'.
+ */
+void
+_mesa_use_uniform(struct gl_program_parameter_list *paramList,
+                  const char *name)
+{
+   GLuint i;
+   for (i = 0; i < paramList->NumParameters; i++) {
+      struct gl_program_parameter *p = paramList->Parameters + i;
+      if (p->Type == PROGRAM_UNIFORM && _mesa_strcmp(p->Name, name) == 0) {
+         p->Used = GL_TRUE;
+         /* Note that large uniforms may occupy several slots so we're
+          * not done searching yet.
+          */
+      }
+   }
+}
+
+
 /**
  * Add a sampler to the parameter list.
  * \param name  uniform's name
@@ -591,21 +611,24 @@ _mesa_clone_parameter_list(const struct gl_program_parameter_list *list)
    /** Not too efficient, but correct */
    for (i = 0; i < list->NumParameters; i++) {
       struct gl_program_parameter *p = list->Parameters + i;
+      struct gl_program_parameter *pCopy;
       GLuint size = MIN2(p->Size, 4);
       GLint j = _mesa_add_parameter(clone, p->Type, p->Name, size, p->DataType,
                                     list->ParameterValues[i], NULL);
       ASSERT(j >= 0);
+      pCopy = clone->Parameters + j;
+      pCopy->Used = p->Used;
       /* copy state indexes */
       if (p->Type == PROGRAM_STATE_VAR) {
          GLint k;
-         struct gl_program_parameter *q = clone->Parameters + j;
          for (k = 0; k < STATE_LENGTH; k++) {
-            q->StateIndexes[k] = p->StateIndexes[k];
+            pCopy->StateIndexes[k] = p->StateIndexes[k];
          }
       }
       else {
          clone->Parameters[j].Size = p->Size;
       }
+      
    }
 
    clone->StateFlags = list->StateFlags;

src/mesa/shader/prog_parameter.h

@@ -48,6 +48,7 @@ struct gl_program_parameter
    enum register_file Type; /**< PROGRAM_NAMED_PARAM, CONSTANT or STATE_VAR */
    GLenum DataType;         /**< GL_FLOAT, GL_FLOAT_VEC2, etc */
    GLuint Size;             /**< Number of components (1..4) */
+   GLboolean Used;          /**< Helper flag for GLSL uniform tracking */
    /**
     * A sequence of STATE_* tokens and integers to identify GL state.
     */
@@ -112,6 +113,10 @@ extern GLint
 _mesa_add_uniform(struct gl_program_parameter_list *paramList,
                   const char *name, GLuint size, GLenum datatype);
 
+extern void
+_mesa_use_uniform(struct gl_program_parameter_list *paramList,
+                  const char *name);
+
 extern GLint
 _mesa_add_sampler(struct gl_program_parameter_list *paramList,
                   const char *name, GLenum datatype);

src/mesa/shader/slang/slang_emit.c

@@ -1703,6 +1703,10 @@ emit_var_ref(slang_emit_info *emitInfo, slang_ir_node *n)
    if (n->Store->File == PROGRAM_STATE_VAR && n->Store->Index < 0) {
       n->Store->Index = _slang_alloc_statevar(n, emitInfo->prog->Parameters);
    }
+   else if (n->Store->File == PROGRAM_UNIFORM) {
+      /* mark var as used */
+      _mesa_use_uniform(emitInfo->prog->Parameters, (char *) n->Var->a_name);
+   }
 
    if (n->Store->Index < 0) {
       /* probably ran out of registers */

src/mesa/shader/slang/slang_link.c

@@ -173,7 +173,7 @@ link_uniform_vars(struct gl_shader_program *shProg,
        * Furthermore, we'll need to fix the state-var's size/datatype info.
        */
 
-      if (p->Type == PROGRAM_UNIFORM ||
+      if ((p->Type == PROGRAM_UNIFORM && p->Used) ||
           p->Type == PROGRAM_SAMPLER) {
          _mesa_append_uniform(shProg->Uniforms, p->Name, prog->Target, i);
       }