Initial bits of constant expression evaluator

Currently only works for constants.  The rest will be added later.

Makefile.am

@@ -27,7 +27,8 @@ glsl_SOURCES = symbol_table.c hash_table.c glsl_types.cpp \
 	glsl_parser.ypp glsl_lexer.lpp glsl_parser_extras.cpp \
 	ast_expr.cpp ast_to_hir.cpp ast_function.cpp ast_type.cpp \
 	ir.cpp hir_field_selection.cpp builtin_function.cpp \
-	ir_print_visitor.cpp ir_variable.cpp ir_function.cpp
+	ir_print_visitor.cpp ir_variable.cpp ir_function.cpp \
+	ir_constant_expression.cpp
 
 BUILT_SOURCES = glsl_parser.h builtin_types.h glsl_parser.cpp glsl_lexer.cpp
 CLEANFILES = $(BUILT_SOURCES)

ir.h

@@ -40,6 +40,7 @@ class ir_instruction : public exec_node {
 public:
    const struct glsl_type *type;
 
+   class ir_constant *constant_expression_value();
    virtual void accept(ir_visitor *) = 0;
 
    /**

ir_constant_expression.cpp

@@ -0,0 +1,191 @@
+/*
+ * Copyright © 2010 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file ir_constant_expression.cpp
+ * Evaluate and process constant valued expressions
+ *
+ * In GLSL, constant valued expressions are used in several places.  These
+ * must be processed and evaluated very early in the compilation process.
+ *
+ *    * Sizes of arrays
+ *    * Initializers for uniforms
+ *    * Initializers for \c const variables
+ */
+
+#define NULL 0
+#include "ir.h"
+#include "ir_visitor.h"
+
+/**
+ * Visitor class for evaluating constant expressions
+ */
+class ir_constant_visitor : public ir_visitor {
+public:
+   ir_constant_visitor()
+      : value(NULL)
+   {
+      /* empty */
+   }
+
+   virtual ~ir_constant_visitor()
+   {
+      /* empty */
+   }
+
+   /**
+    * \name Visit methods
+    *
+    * As typical for the visitor pattern, there must be one \c visit method for
+    * each concrete subclass of \c ir_instruction.  Virtual base classes within
+    * the hierarchy should not have \c visit methods.
+    */
+   /*@{*/
+   virtual void visit(ir_variable *);
+   virtual void visit(ir_label *);
+   virtual void visit(ir_function_signature *);
+   virtual void visit(ir_function *);
+   virtual void visit(ir_expression *);
+   virtual void visit(ir_swizzle *);
+   virtual void visit(ir_dereference *);
+   virtual void visit(ir_assignment *);
+   virtual void visit(ir_constant *);
+   virtual void visit(ir_call *);
+   virtual void visit(ir_return *);
+   virtual void visit(ir_if *);
+   /*@}*/
+
+   /**
+    * Value of the constant expression.
+    *
+    * \note
+    * This field will be \c NULL if the expression is not constant valued.
+    */
+   /* FINIHSME: This cannot hold values for constant arrays or structures. */
+   ir_constant *value;
+};
+
+
+ir_constant *
+ir_instruction::constant_expression_value()
+{
+   ir_constant_visitor visitor;
+
+   this->accept(& visitor);
+   return visitor.value;
+}
+
+
+void
+ir_constant_visitor::visit(ir_variable *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_label *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_function_signature *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_function *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_expression *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_swizzle *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_dereference *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_assignment *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_constant *ir)
+{
+   value = ir;
+}
+
+
+void
+ir_constant_visitor::visit(ir_call *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_return *ir)
+{
+   (void) ir;
+   value = NULL;
+}
+
+
+void
+ir_constant_visitor::visit(ir_if *ir)
+{
+   (void) ir;
+   value = NULL;
+}