cps-ir: Support foreign code.

pkg/compiler/lib/src/tree_ir/tree_ir_tracer.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 tree_ir_tracer;
 
 import 'dart:async' show EventSink;
 import '../tracer.dart';
 import 'tree_ir_nodes.dart';
 
@@ skipping 154 matching lines @@
     visitStatement(node.catchBody);
 
     substatements[node.tryBody] = tryBlock;
     substatements[node.catchBody] = catchBlock;
   }
 
   visitExpressionStatement(ExpressionStatement node) {
     _addStatement(node);
     visitStatement(node.next);
   }
+
+  visitForeignStatement(ForeignStatement node) {
+    _addStatement(node);
+  }
 }
 
 class TreeTracer extends TracerUtil with StatementVisitor {
   String get passName => null;
 
   final EventSink<String> output;
 
   TreeTracer(this.output);
 
   List<Variable> parameters;
@@ skipping 129 matching lines @@
     String value = expr(node.value);
     if (SubexpressionVisitor.usesInfixNotation(node.object)) {
       object = '($object)';
     }
     printStatement(null, '$object.$field = $value');
   }
 
   String expr(Expression e) {
     return e.accept(new SubexpressionVisitor(names));
   }
+
+  @override
+  visitForeignStatement(ForeignStatement node) {
+    printStatement(null, 'foreign');
+  }
 }
 
 class SubexpressionVisitor extends ExpressionVisitor<String> {
   Names names;
 
   SubexpressionVisitor(this.names);
 
   String visitVariableUse(VariableUse node) {
     return names.varName(node.variable);
   }
@@ skipping 168 matching lines @@
   @override
   String visitTypeExpression(TypeExpression node) {
     return node.dartType.toString();
   }
 
   @override
   String visitCreateInvocationMirror(CreateInvocationMirror node) {
     String args = node.arguments.map(visitExpression).join(', ');
     return 'CreateInvocationMirror(${node.selector.name}, $args)';
   }
+
+  @override
+  String visitForeignExpression(ForeignExpression node) {
+    String arguments = node.arguments.map(visitExpression).join(', ');
+    return 'Foreign "${node.codeTemplate}"($arguments)';
+  }
 }
 
 /**
  * Invents (and remembers) names for Variables that do not have an associated
  * identifier.
  *
  * In case a variable is named v0, v1, etc, it may be assigned a different
  * name to avoid clashing with a previously synthesized variable name.
  */
 class Names {
   final Map<Variable, String> _names = {};
   final Set<String> _usedNames = new Set();
   int _counter = 0;
 
   String varName(Variable v) {
     String name = _names[v];
     if (name == null) {
       String prefix = v.element == null ? 'v' : '${v.element.name}_';
       while (name == null || _usedNames.contains(name)) {
         name = "$prefix${_counter++}";
       }
       _names[v] = name;
       _usedNames.add(name);
     }
     return name;
   }
 }