cps-ir: Add a test for codegeneration.

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library code_generator;
 
+import 'glue.dart';
+
 import '../../tree_ir/tree_ir_nodes.dart' as tree_ir;
 import '../../js/js.dart' as js;
 import '../../elements/elements.dart';
 import '../../util/maplet.dart';
+import '../../constants/values.dart';
+import '../../dart2jslib.dart';
 
 class CodegenBailout {
   final tree_ir.Node node;
   final String reason;
   CodegenBailout(this.node, this.reason);
   String get message {
     return 'bailout${node != null ? " on $node" : ""}: $reason';
   }
 }
 
 class CodeGenerator extends tree_ir.Visitor<dynamic, js.Expression> {
+  final CodegenRegistry registry;
+
+  final Glue glue;
+
   /// Variables to be hoisted at the top of the current function.
   List<js.VariableDeclaration> variables = <js.VariableDeclaration>[];
 
   /// Maps variables to their name.
   Map<tree_ir.Variable, String> variableNames = <tree_ir.Variable, String>{};
 
   /// Maps local constants to their name.
   Maplet<VariableElement, String> constantNames =
       new Maplet<VariableElement, String>();
 
   /// Variables that have had their declaration created.
   Set<tree_ir.Variable> declaredVariables = new Set<tree_ir.Variable>();
 
   /// Variable names that have already been used. Used to avoid name clashes.
   Set<String> usedVariableNames;
 
-  List<js.Parameter> parameters;
+  List<js.Parameter> parameters = new List<js.Parameter>();
   List<js.Statement> accumulator = new List<js.Statement>();
 
   js.Block body;
 
   /// Generates JavaScript code for the body of [function].
   /// The code will be in [body] and the parameters will be in [parameters].
+  CodeGenerator(this.glue, this.registry);
+
   void buildFunction(tree_ir.FunctionDefinition function) {
     visitStatement(function.body);
     for (tree_ir.Variable parameter in function.parameters) {
       parameters.add(new js.Parameter(variableNames[parameter]));
     }
     body = new js.Block(accumulator);
   }
 
   List<js.Expression> visitArguments(List<tree_ir.Expression> arguments) {
     return arguments.map(visitExpression).toList();
@@ skipping 11 matching lines @@
   }
 
   @override
   js.Expression visitConditional(tree_ir.Conditional node) {
     return giveup(node);
     // TODO: implement visitConditional
   }
 
   @override
   js.Expression visitConstant(tree_ir.Constant node) {
-    return giveup(node);
-    // TODO: implement visitConstant
+    ConstantValue constant = node.expression.value;
+    registry.registerCompileTimeConstant(constant);
+    return glue.constantReference(constant);
   }
 
   @override
   js.Expression visitFunctionExpression(tree_ir.FunctionExpression node) {
     return giveup(node);
     // TODO: implement visitFunctionExpression
   }
 
   @override
   js.Expression visitInvokeConstructor(tree_ir.InvokeConstructor node) {
@@ skipping 122 matching lines @@
     // TODO: implement visitWhileTrue
   }
 
   @override
   void visitReturn(tree_ir.Return node) {
     if (node.value != null) {
       accumulator.add(new js.Return(visitExpression(node.value)));
     }
   }
 }