CoreJIT snapshots without training.

tools/gn.py

 #!/usr/bin/env python
 # Copyright 2016 The Dart project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import argparse
 import multiprocessing
 import os
 import shutil
 import subprocess
@@ skipping 367 matching lines @@
       default=os_has_ide(HOST_OS),
       action='store_true')
   other_group.add_argument('--msan',
       help='Build with MSAN',
       default=UseMSAN(),
       action='store_true')
   other_group.add_argument('--no-msan',
       help='Disable MSAN',
       dest='msan',
       action='store_false')
+  other_group.add_argument('--gn-args',
+      help='Set extra GN args',
+      dest='gn_args',
+      action='append')
   other_group.add_argument('--platform-sdk',
       help='Directs the create_sdk target to create a smaller "Platform" SDK',
       default=MakePlatformSDK(),
       action='store_true')
   other_group.add_argument('--target-sysroot', '-s',
       type=str,
       help='Comma-separated list of arch=/path/to/sysroot mappings')
   other_group.add_argument('--toolchain-prefix', '-t',
       type=str,
       help='Comma-separated list of arch=/path/to/toolchain-prefix mappings')
@@ skipping 53 matching lines @@
     return 1
   gn = os.path.join(DART_ROOT, 'buildtools', subdir, 'gn')
 
   commands = []
   for target_os in args.os:
     for mode in args.mode:
       for arch in args.arch:
         out_dir = GetOutDir(mode, arch, target_os)
         command = [gn, 'gen', out_dir, '--check']
         gn_args = ToCommandLine(ToGnArgs(args, mode, arch, target_os))
+        if args.gn_args != None:
+          gn_args += args.gn_args
         if args.verbose:
           print "gn gen --check in %s" % out_dir
         if args.ide:
           command.append(ide_switch(HOST_OS))
         command.append('--args=%s' % ' '.join(gn_args))
         commands.append(command)
 
   pool = multiprocessing.Pool(args.workers)
   results = pool.map(RunCommand, commands, chunksize=1)
   for r in results:
     if r != 0:
       print r.strip()
       return 1
 
   endtime = time.time()
   if args.verbose:
     print ("GN Time: %.3f seconds" % (endtime - starttime))
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(Main(sys.argv))