Introduce cfi_vptr build flag.

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 628 matching lines @@
       'use_lto%': 0,
       # Enable LTO on code compiled with -O2.
       'use_lto_o2%': 0,
 
       # Allowed level of identical code folding in the gold linker.
       'gold_icf_level%': 'safe',
 
       # Libxkbcommon usage.
       'use_xkbcommon%': 0,
 
+      # Control Flow Integrity for virtual calls.
+      # See http://clang.llvm.org/docs/ControlFlowIntegrity.html
+      'cfi_vptr%': 0,
+
       'conditions': [
         # A flag for POSIX platforms
         ['OS=="win"', {
           'os_posix%': 0,
         }, {
           'os_posix%': 1,
         }],
 
         # A flag for BSD platforms
         ['OS=="freebsd" or OS=="openbsd"', {
@@ skipping 554 matching lines @@
     'v8_optimized_debug%': '<(v8_optimized_debug)',
     'proprietary_codecs%': '<(proprietary_codecs)',
     'use_goma%': '<(use_goma)',
     'gomadir%': '<(gomadir)',
     'use_lto%': '<(use_lto)',
     'use_lto_o2%': '<(use_lto_o2)',
     'gold_icf_level%': '<(gold_icf_level)',
     'video_hole%': '<(video_hole)',
     'support_pre_M6_history_database%': '<(support_pre_M6_history_database)',
     'v8_use_external_startup_data%': '<(v8_use_external_startup_data)',
+    'cfi_vptr%': '<(cfi_vptr)',
 
     # Use system protobuf instead of bundled one.
     'use_system_protobuf%': 0,
 
     # Use system yasm instead of bundled one.
     'use_system_yasm%': 0,
 
     # Use system ICU instead of bundled one.
     'use_system_icu%' : 0,
 
@@ skipping 1755 matching lines @@
       }],
       ['enable_ipc_fuzzer==1', {
         'defines': ['ENABLE_IPC_FUZZER=1'],
       }],
       ['video_hole==1', {
         'defines': ['VIDEO_HOLE=1'],
       }],
       ['v8_use_external_startup_data==1', {
        'defines': ['V8_USE_EXTERNAL_STARTUP_DATA'],
       }],
-      ['use_lto==1 and (target_arch=="ia32" or target_arch=="x64")', {
+      ['(use_lto==1 or cfi_vptr==1) and (target_arch=="ia32" or target_arch=="x64")', {

[Nico, 2015/03/06 21:13:25]

alternatively use_lto could be set to 1 automatically if cfi_vptr is set (like
asan=1 used to set clang=1)

         # Required for third_party/zlib/crc_folding.c and various other code
         # that uses SSE. TODO(pcc): Remove this once we properly support
         # subtarget specific code generation in LLVM.
         'ldflags': ['-Wl,-plugin-opt,mcpu=corei7-avx'],
       }],
     ],  # conditions for 'target_defaults'
     'target_conditions': [
       ['<(use_libpci)==1', {
         'defines': ['USE_LIBPCI=1'],
       }],
@@ skipping 2887 matching lines @@
       'target_defaults': {
         'target_conditions': [
           ['_toolset=="target"', {
             'cflags': [
               '-ffat-lto-objects',
             ],
           }],
         ],
       },
     }],
-    ['use_lto==1 and clang==1', {
+    ['(use_lto==1 or cfi_vptr==1) and clang==1', {
       'target_defaults': {
         'target_conditions': [
           ['_toolset=="target"', {
             'arflags': [
               '--plugin', '../../<(make_clang_dir)/lib/LLVMgold.so',
             ],
           }],
         ],
       },
     }],
@@ skipping 12 matching lines @@
       'target_defaults': {
         'target_conditions': [
           ['_toolset=="target"', {
             'ldflags': [
               '-flto',
             ],
           }],
         ],
       },
     }],
+    ['cfi_vptr==1', {
+      'target_defaults': {
+        'target_conditions': [
+          ['_toolset=="target"', {
+            'cflags': [
+              '-fsanitize=cfi-vptr',
+            ],
+            'ldflags': [
+              '-fsanitize=cfi-vptr',
+            ],
+          }],
+        ],
+      },
+    }],
   ],
   'xcode_settings': {
     # DON'T ADD ANYTHING NEW TO THIS BLOCK UNLESS YOU REALLY REALLY NEED IT!
     # This block adds *project-wide* configuration settings to each project
     # file.  It's almost always wrong to put things here.  Specify your
     # custom xcode_settings in target_defaults to add them to targets instead.
 
     'conditions': [
       # In an Xcode Project Info window, the "Base SDK for All Configurations"
       # setting sets the SDK on a project-wide basis. In order to get the
@@ skipping 50 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }