Improvements to the kernel tree shaker.

pkg/kernel/test/treeshaker_dump.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_dump;
 
 import 'dart:io';
 import 'package:kernel/kernel.dart';
 import 'package:kernel/transformations/treeshaker.dart';
 import 'package:args/args.dart';
 import 'package:path/path.dart' as pathlib;
 import 'package:kernel/text/ast_to_text.dart';
 
 ArgParser parser = new ArgParser(allowTrailingOptions: true)
   ..addFlag('used', help: 'Print used members', negatable: false)
   ..addFlag('unused', help: 'Print unused members', negatable: false)
   ..addFlag('instantiated',
       help: 'Print instantiated classes', negatable: false)
   ..addFlag('types', help: 'Print classes used as a type', negatable: false)
   ..addFlag('summary',
       help: 'Print short summary of tree shaking results', defaultsTo: true)
   ..addFlag('diff',
       help: 'Print textual output before and after tree shaking.\n'
           'Files are written to FILE.before.txt and FILE.after.txt',
       negatable: false)
   ..addOption('output',
       help: 'The --diff files are written to the given directory instead of '
-          'the working directory');
+          'the working directory')
+  ..addFlag('strong', help: 'Run the tree shaker in strong mode');
 
 String usage = '''
 Usage: treeshaker_dump [options] FILE.dill
 
 Runs tree shaking on the given program and prints information about the results.
 
 Example:
   treeshaker_dump --instantiated foo.dill
 
 Example:
@@ skipping 15 matching lines @@
     print('Exactly one file should be given.');
     exit(1);
   }
   String filename = options.rest.single;
 
   if (options['output'] != null && !options['diff']) {
     print('--output must be used with --diff');
     exit(1);
   }
 
+  bool strong = options['strong'];
+
   Program program = loadProgramFromBinary(filename);
-  TreeShaker shaker = new TreeShaker(program);
+  TreeShaker shaker = new TreeShaker(program, strongMode: strong);
   int totalClasses = 0;
   int totalInstantiationCandidates = 0;
   int totalMembers = 0;
   int usedClasses = 0;
   int instantiatedClasses = 0;
   int usedMembers = 0;
 
   void visitMember(Member member) {
     if (member.isAbstract) return; // Abstract members are not relevant.
     ++totalMembers;
-    bool isUsed = shaker.isMemberUsed(member);
+    bool isUsed = shaker.isMemberBodyUsed(member);
     if (isUsed) {
       ++usedMembers;
     }
     if (isUsed && options['used'] || !isUsed && options['unused']) {
       String prefix = (options['used'] && options['unused'])
           ? (isUsed ? 'USED   ' : 'UNUSED ')
           : '';
       print('$prefix$member');
     }
   }
@@ skipping 31 matching lines @@
 
   if (options['diff']) {
     String name = pathlib.basenameWithoutExtension(filename);
     String outputDir = options['output'] ?? '';
     String beforeFile = pathlib.join(outputDir, '$name.before.txt');
     String afterFile = pathlib.join(outputDir, '$name.after.txt');
     NameSystem names = new NameSystem();
     StringBuffer before = new StringBuffer();
     new Printer(before, syntheticNames: names).writeProgramFile(program);
     new File(beforeFile).writeAsStringSync('$before');
-    new TreeShaker(program).transform(program);
+    new TreeShaker(program, strongMode: strong).transform(program);
     StringBuffer after = new StringBuffer();
     new Printer(after, syntheticNames: names).writeProgramFile(program);
     new File(afterFile).writeAsStringSync('$after');
     print('Text written to $beforeFile and $afterFile');
   }
 }
 
 String ratio(num x, num total) {
   return '$x / $total (${percent(x, total)})';
 }
 
 String percent(num x, num total) {
   return total == 0 ? '0%' : ((100 * x / total).toStringAsFixed(0) + '%');
 }