MSan: introduce a GYP flag to control origin tracking.

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 335 matching lines @@
       # Run tools/clang/scripts/update.sh to make sure they are compiled.
       # This causes 'clang_chrome_plugins_flags' to be set.
       # Has no effect if 'clang' is not set as well.
       'clang_use_chrome_plugins%': 1,
 
       # Enable building with ASAN (Clang's -fsanitize=address option).
       # -fsanitize=address only works with clang, but asan=1 implies clang=1
       # See https://sites.google.com/a/chromium.org/dev/developers/testing/addresssanitizer
       'asan%': 0,
       # Enable coverage gathering instrumentation in ASan. This flag also
-      # controls coverage granularity (experimental).
+      # controls coverage granularity (1 for function-level coverage, 2 for
+      # block-level coverage).
       'asan_coverage%': 0,
 
       # Enable Chromium overrides of the default configurations for various
       # dynamic tools (like ASan).
       'use_sanitizer_options%': 1,
 
       # Enable building with SyzyAsan.
       # See https://code.google.com/p/sawbuck/wiki/SyzyASanHowTo
       'syzyasan%': 0,
 
       # Enable building with LSan (Clang's -fsanitize=leak option).
       # -fsanitize=leak only works with clang, but lsan=1 implies clang=1
       # See https://sites.google.com/a/chromium.org/dev/developers/testing/leaksanitizer
       'lsan%': 0,
 
       # Enable building with TSan (Clang's -fsanitize=thread option).
       # -fsanitize=thread only works with clang, but tsan=1 implies clang=1
       # See http://clang.llvm.org/docs/ThreadSanitizer.html
       'tsan%': 0,
       'tsan_blacklist%': '<(PRODUCT_DIR)/../../tools/valgrind/tsan_v2/ignores.txt',
 
       # Enable building with MSan (Clang's -fsanitize=memory option).
       # MemorySanitizer only works with clang, but msan=1 implies clang=1
       # See http://clang.llvm.org/docs/MemorySanitizer.html
       'msan%': 0,
       'msan_blacklist%': '<(PRODUCT_DIR)/../../tools/msan/blacklist.txt',
+      # Track where uninitialized memory originates from. From fastest to
+      # slowest: 0 - no tracking, 1 - track only the initial allocation site, 2
+      # - track the chain of stores leading from allocation site to use site.
+      'msan_track_origins%': 1,
 
       # Enable building with UBSan (Clang's -fsanitize=undefined option).
       # -fsanitize=undefined only works with clang, but ubsan=1 implies clang=1
       # See http://clang.llvm.org/docs/UsersManual.html
       'ubsan%': 0,
 
       # Use the dynamic libraries instrumented by one of the sanitizers
       # instead of the standard system libraries.
       'use_instrumented_libraries%': 0,
 
@@ skipping 666 matching lines @@
     'clang_use_chrome_plugins%': '<(clang_use_chrome_plugins)',
     'mac_want_real_dsym%': '<(mac_want_real_dsym)',
     'asan%': '<(asan)',
     'asan_coverage%': '<(asan_coverage)',
     'use_sanitizer_options%': '<(use_sanitizer_options)',
     'syzyasan%': '<(syzyasan)',
     'syzygy_optimize%': '<(syzygy_optimize)',
     'lsan%': '<(lsan)',
     'msan%': '<(msan)',
     'msan_blacklist%': '<(msan_blacklist)',
+    'msan_track_origins%': '<(msan_track_origins)',
     'tsan%': '<(tsan)',
     'tsan_blacklist%': '<(tsan_blacklist)',
     'ubsan%': '<(ubsan)',
     'use_instrumented_libraries%': '<(use_instrumented_libraries)',
     'use_custom_libcxx%': '<(use_custom_libcxx)',
     'clang_type_profiler%': '<(clang_type_profiler)',
     'order_profiling%': '<(order_profiling)',
     'order_text_section%': '<(order_text_section)',
     'enable_extensions%': '<(enable_extensions)',
     'enable_plugin_installation%': '<(enable_plugin_installation)',
@@ skipping 2891 matching lines @@
                   }],
                 ],
               }],
             ],
           }],
           ['msan==1', {
             'target_conditions': [
               ['_toolset=="target"', {
                 'cflags': [
                   '-fsanitize=memory',
-                  '-fsanitize-memory-track-origins',
+                  '-fsanitize-memory-track-origins=<(msan_track_origins)',
                   '-fPIC',
                   '-fsanitize-blacklist=<(msan_blacklist)',
                 ],
                 'ldflags': [
                   '-fsanitize=memory',
                 ],
                 'defines': [
                   'MEMORY_SANITIZER',
                 ],
                 'target_conditions': [
@@ skipping 1490 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',
   },
 }