Handle constant expressions using derefs of const values.

Fixes CorrectParse1.frag and makes for a ton of folding in
CorrectParse2.frag.

ast_to_hir.cpp

@@ -1603,12 +1603,15 @@ ast_declarator_list::hir(exec_list *instructions,
 	  * declaration.
 	  */
 	 if (this->type->qualifier.constant) {
-	    rhs = rhs->constant_expression_value();
-	    if (!rhs) {
+	    ir_constant *constant_value = rhs->constant_expression_value();
+	    if (!constant_value) {
 	       _mesa_glsl_error(& initializer_loc, state,
 				"initializer of const variable `%s' must be a "
 				"constant expression",
 				decl->identifier);
+	    } else {
+	       rhs = constant_value;
+	       var->constant_value = constant_value;
 	    }
 	 }
 

ir.cpp

@@ -338,6 +338,7 @@ ir_variable::ir_variable(const struct glsl_type *type, const char *name)
 {
    this->type = type;
    this->name = name;
+   this->constant_value = NULL;
 
    if (type && type->base_type == GLSL_TYPE_SAMPLER)
       this->read_only = true;

ir.h

@@ -154,6 +154,11 @@ public:
     * equality).  This flag enables this behavior.
     */
    unsigned array_lvalue:1;
+
+   /**
+    * Value assigned in the initializer of a variable declared "const"
+    */
+   ir_constant *constant_value;
 };
 
 

ir_constant_expression.cpp

@@ -395,8 +395,15 @@ ir_constant_visitor::visit(ir_swizzle *ir)
 void
 ir_constant_visitor::visit(ir_dereference *ir)
 {
-   (void) ir;
    value = NULL;
+
+   if (ir->mode == ir_dereference::ir_reference_variable) {
+      ir_variable *var = ir->var->as_variable();
+      if (var && var->constant_value) {
+	 value = new ir_constant(ir->type, &var->constant_value->value);
+      }
+   }
+   /* FINISHME: Other dereference modes. */
 }