LLVM_LTO support for make / ninja

pylib/gyp/xcode_emulation.py

 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """
 This module contains classes that help to emulate xcodebuild behavior on top of
 other build systems, such as make and ninja.
 """
 
 import copy
@@ skipping 507 matching lines @@
 
     if self._Test('GCC_SYMBOLS_PRIVATE_EXTERN', 'YES', default='NO'):
       cflags.append('-fvisibility=hidden')
 
     if self._Test('GCC_TREAT_WARNINGS_AS_ERRORS', 'YES', default='NO'):
       cflags.append('-Werror')
 
     if self._Test('GCC_WARN_ABOUT_MISSING_NEWLINE', 'YES', default='NO'):
       cflags.append('-Wnewline-eof')
 
+    # In Xcode, this is only activated when GCC_COMPILER_VERSION is clang or
+    # llvm-gcc. It also requires a fairly recent libtool, and
+    # if the system clang isn't used, DYLD_LIBRARY_PATH needs to contain the
+    # path to the libLTO.dylib that matches the used clang.
+    if self._Test('LLVM_LTO', 'YES', default='NO'):
+      cflags.append('-flto')
+

[scottmg, 2015/04/01 23:50:21]

nit; extra \n

+
     self._AppendPlatformVersionMinFlags(cflags)
 
     # TODO:
     if self._Test('COPY_PHASE_STRIP', 'YES', default='NO'):
       self._WarnUnimplemented('COPY_PHASE_STRIP')
     self._WarnUnimplemented('GCC_DEBUGGING_SYMBOLS')
     self._WarnUnimplemented('GCC_ENABLE_OBJC_EXCEPTIONS')
 
     # TODO: This is exported correctly, but assigning to it is not supported.
     self._WarnUnimplemented('MACH_O_TYPE')
@@ skipping 1055 matching lines @@
       if toolset == 'target':
         iphoneos_config_dict['xcode_settings']['SDKROOT'] = 'iphoneos'
   return targets
 
 def CloneConfigurationForDeviceAndEmulator(target_dicts):
   """If |target_dicts| contains any iOS targets, automatically create -iphoneos
   targets for iOS device builds."""
   if _HasIOSTarget(target_dicts):
     return _AddIOSDeviceConfigurations(target_dicts)
   return target_dicts