GN: Fix cross ARM64 and cross MIPS builds.

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 subprocess
 import sys
@@ skipping 125 matching lines @@
 
   # Use tcmalloc only when targeting Linux and when not using ASAN.
   gn_args['dart_use_tcmalloc'] = ((gn_args['target_os'] == 'linux')
                                   and not args.asan
                                   and not args.msan
                                   and not args.tsan)
 
   # Force -mfloat-abi=hard and -mfpu=neon on Linux as we're specifying
   # a gnueabihf compiler in //build/toolchain/linux BUILD.gn.
   # TODO(zra): This will likely need some adjustment to build for armv6 etc.
-  hard_float = (gn_args['target_cpu'].startswith('arm') and
+  hard_float = ((gn_args['target_cpu'] == 'arm') and

[zra, 2017/01/18 03:21:33]

Add a TODO that this will need to change if we want to continue supporting armv6
and armv5te, or refine this test to include those but exclude arm64.

[rmacnak, 2017/01/20 22:54:47]

Added branches that throw with an unimplemented message for armv6/5te.

                 (gn_args['target_os'] == 'linux'))
   if hard_float:
     gn_args['arm_float_abi'] = 'hard'
     gn_args['arm_use_neon'] = True
 
   gn_args['is_debug'] = mode == 'debug'
   gn_args['is_release'] = mode == 'release'
   gn_args['is_product'] = mode == 'product'
   gn_args['dart_debug'] = mode == 'debug'
 
@@ skipping 259 matching lines @@
       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))