Enable generation of instruction buffer on precompilation

runtime/BUILD.gn

 # 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.
 
 # TODO(zra): These build arguments should likely be moved to a gni file that is
 # included in BUILD.gn files that care about the values of the flags. For now,
 # since the GN build only happens as part of a Mojo build there is no need for
 # the indirection.
 declare_args() {
   # Instead of using is_debug, we introduce a different flag for specifying a
   # Debug build of Dart so that clients can still use a Release build of Dart
   # while themselves doing a Debug build.
   dart_debug = false
 }
 
 config("dart_public_config") {
   include_dirs = [
     ".",
   ]
 }
 
 config("dart_config") {
   defines = []
+  if (target_os == "ios") {
+    # For precompilation, we need to set the target architecture when we
+    # compile the snapshotter on the host. If no instruction buffer is created

[rmacnak, 2015/10/22 16:46:15]

The snapshotter is osx not ios.

It would be better to use an explicit flag for this rather than have every GN
build of a OSX VM using a simulator.

[Chinmay, 2015/10/22 19:01:29]

ack

+    # on the host, this argument is of no consequence.
+    defines += ["TARGET_ARCH_ARM64"]
+  }
   if (dart_debug) {
     defines += ["DEBUG"]
   } else {
     defines += ["NDEBUG"]
   }
 
   cflags = [
     "-Werror",
     "-Wall",
     "-Wextra", # Also known as -W.
@@ skipping 87 matching lines @@
     "vm:libdart_lib_nosnapshot",
     "vm:libdart_lib",
     "vm:libdart_vm",
     "vm:libdart_platform",
     "third_party/double-conversion/src:libdouble_conversion",
   ]
   sources = [
     "vm/libdart_dependency_helper.cc",
   ]
 }