Improvements to the kernel tree shaker.

pkg/kernel/test/treeshaker_membench.dart

 #!/usr/bin/env dart
 // Copyright (c) 2016, 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 kernel.treeshaker_membench;
 
 import 'package:kernel/kernel.dart';
 import 'package:kernel/transformations/treeshaker.dart';
 import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/core_types.dart';
 import 'package:args/args.dart';
 import 'dart:io';
 
-ArgParser argParser = new ArgParser()
+ArgParser argParser = new ArgParser(allowTrailingOptions: true)
   ..addOption('count',
-      abbr: 'c', help: 'Build N copies of the tree shaker', defaultsTo: '100');
+      abbr: 'c', help: 'Build N copies of the tree shaker', defaultsTo: '100')
+  ..addFlag('strong', help: 'Run the tree shaker in strong mode');
 
 String usage = """
-Usage: treeshaker_membench [options] FILE.dart
+Usage: treeshaker_membench [options] FILE.dill
 
 Options:
 ${argParser.usage}
 """;
 
 /// Builds N copies of the tree shaker data structure for the given program.
 /// Pass --print-metrics to the Dart VM to measure the memory use.
 main(List<String> args) {
   if (args.length == 0) {
     print(usage);
     exit(1);
   }
   ArgResults options = argParser.parse(args);
   if (options.rest.length != 1) {
     print('Exactly one file should be given');
     exit(1);
   }
   String filename = options.rest.single;
+  bool strongMode = options['strong'];
 
   Program program = loadProgramFromBinary(filename);
   ClassHierarchy hierarchy = new ClassHierarchy(program);
   CoreTypes coreTypes = new CoreTypes(program);
 
   int copyCount = int.parse(options['count']);
 
   TreeShaker buildTreeShaker() {
-    return new TreeShaker(program, hierarchy: hierarchy, coreTypes: coreTypes);
+    return new TreeShaker(program,
+        hierarchy: hierarchy, coreTypes: coreTypes, strongMode: strongMode);
   }
 
   List<TreeShaker> keepAlive = <TreeShaker>[];
   for (int i = 0; i < copyCount; ++i) {
     keepAlive.add(buildTreeShaker());
   }
 
   print('$copyCount copies built');
 
   if (args.contains('-v')) {
     // Use of the list for something to avoid premature GC.
     for (var treeShaker in keepAlive) {
       treeShaker.getClassRetention(hierarchy.rootClass);
     }
   }
 }