Add msan build option.

build/standalone.gypi

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 17 matching lines @@
 # Definitions to be used when building stand-alone V8 binaries.
 
 {
   # We need to include toolchain.gypi here for third-party sources that don't
   # directly include it themselves.
   'includes': ['toolchain.gypi'],
   'variables': {
     'component%': 'static_library',
     'clang%': 0,
     'asan%': 0,
+    'msan%': 0,
     'visibility%': 'hidden',
     'v8_enable_backtrace%': 0,
     'v8_enable_i18n_support%': 1,
     'v8_deprecation_warnings': 1,
     'msvs_multi_core_compile%': '1',
     'mac_deployment_target%': '10.5',
     'variables': {
       'variables': {
         'variables': {
           'conditions': [
@@ skipping 130 matching lines @@
           '-w',  # http://crbug.com/162783
         ],
         'cflags_cc!': [
           '-fomit-frame-pointer',
         ],
         'ldflags': [
           '-fsanitize=address',
         ],
       },
     }],
+    ['msan==1', {
+      'target_defaults': {
+        'cflags_cc+': [
+          '-fno-omit-frame-pointer',
+          '-fsanitize-memory-track-origins=2',

[earthdok, 2014/07/01 12:13:22]

-fsanitize-memory-track-origins can take values from 0 (fastest, least amount of
information) to 2 (slowest, most helpful reports, experimental). Please expose
this setting rather than hardcode it to 2.

+          '-fsanitize=memory',
+          '-w',  # http://crbug.com/162783

[earthdok, 2014/07/01 12:13:22]

The linked issue refers to ASan, not MSan. We don't use -w with MSan in Chrome
and shouldn't need it for V8, either.

+        ],
+        'cflags_cc!': [
+          '-fomit-frame-pointer',
+        ],
+        'ldflags': [
+          '-fsanitize=memory',
+        ],
+      },
+    }],
     ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
        or OS=="netbsd"', {
       'target_defaults': {
         'cflags': [ '-Wall', '<(werror)', '-W', '-Wno-unused-parameter',
                     '-Wno-long-long', '-pthread', '-fno-exceptions',
                     '-pedantic' ],
         'cflags_cc': [ '-Wnon-virtual-dtor', '-fno-rtti' ],
         'ldflags': [ '-pthread', ],
         'conditions': [
           [ 'OS=="linux"', {
@@ skipping 154 matching lines @@
         ],
         'target_conditions': [
           ['_type!="static_library"', {
             'xcode_settings': {'OTHER_LDFLAGS': ['-Wl,-search_paths_first']},
           }],
         ],  # target_conditions
       },  # target_defaults
     }],  # OS=="mac"
   ],
 }