Add gn option 'is_lto' to enable Link Time Optimization builds.

build/config/sanitizers/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 # Contains the dependencies needed for sanitizers to link into executables and
 # shared_libraries. Unconditionally depend upon this target as it is empty if
@@ skipping 74 matching lines @@
     }
     if (is_msan) {
       ldflags += [ "-fsanitize=memory" ]
     }
     if (is_ubsan) {
       ldflags += [ "-fsanitize=undefined" ]
     }
     if (is_ubsan_vptr) {
       ldflags += [ "-fsanitize=vptr" ]
     }
-    if (is_cfi && !is_nacl) {
-      ldflags += [
-        "-flto",
-        "-fsanitize=cfi-vcall",
-        "-fsanitize=cfi-derived-cast",
-        "-fsanitize=cfi-unrelated-cast",
-      ]
+    if (is_lto && !is_nacl) {
+      ldflags += [ "-flto" ]
 
       # Apply a lower LTO optimization level as the default is too slow.
       if (is_linux) {
         ldflags += [ "-Wl,-plugin-opt,O1" ]
       } else if (is_mac) {
         ldflags += [ "-Wl,-mllvm,-O1" ]
       }
 
       # Work-around for http://openradar.appspot.com/20356002
       if (is_mac) {
         ldflags += [ "-Wl,-all_load" ]
       }
 
       # Without this flag, LTO produces a .text section that is larger
       # than the maximum call displacement, preventing the linker from
       # relocating calls (http://llvm.org/PR22999).
       if (current_cpu == "arm") {
         ldflags += [ "-Wl,-plugin-opt,-function-sections" ]
       }
 
+      if (is_cfi) {
+        ldflags += [
+          "-fsanitize=cfi-vcall",
+          "-fsanitize=cfi-derived-cast",
+          "-fsanitize=cfi-unrelated-cast",
+        ]
+      }
+
       if (use_cfi_diag) {
         ldflags += [
           "-fno-sanitize-trap=cfi",
           "-fsanitize-recover=cfi",
         ]
       }
     }
   }
 }
 
 # This config is applied by default to all targets. It sets the compiler flags
 # for sanitizer usage, or, if no sanitizer is set, does nothing.
 #
 # This needs to be in a separate config so that targets can opt out of
 # sanitizers (by removing the config) if they desire. Even if a target
 # removes this config, executables & shared libraries should still depend on
 # :deps if any of their dependencies have not opted out of sanitizers.
 config("default_sanitizer_flags") {
   cflags = []
   cflags_cc = []
   defines = []
   configs = [ ":default_sanitizer_ldflags" ]
 
   # Only works on Posix-like platforms.
   # FIXME: this is not true, remove the conditional.
   if (is_posix) {
     # Common options for AddressSanitizer, LeakSanitizer, ThreadSanitizer,
     # MemorySanitizer and non-official CFI builds.
-    if (using_sanitizer || (is_cfi && !is_official_build)) {
+    if (using_sanitizer || (is_lto && !is_official_build)) {
       cflags += [
         "-fno-omit-frame-pointer",
         "-gline-tables-only",
       ]
     }
     if (is_asan) {
       asan_blacklist_path =
           rebase_path("//tools/memory/asan/blacklist.txt", root_build_dir)
       cflags += [
         "-fsanitize=address",
@@ skipping 75 matching lines @@
       }
     }
     if (is_ubsan_vptr) {
       ubsan_vptr_blacklist_path =
           rebase_path("//tools/ubsan/vptr_blacklist.txt", root_build_dir)
       cflags += [
         "-fsanitize=vptr",
         "-fsanitize-blacklist=$ubsan_vptr_blacklist_path",
       ]
     }
-    if (is_cfi && !is_nacl) {
-      cfi_blacklist_path =
-          rebase_path("//tools/cfi/blacklist.txt", root_build_dir)
-      cflags += [
-        "-flto",
-        "-fsanitize=cfi-vcall",
-        "-fsanitize=cfi-derived-cast",
-        "-fsanitize=cfi-unrelated-cast",
-        "-fsanitize-blacklist=$cfi_blacklist_path",
-      ]
+    if (is_lto && !is_nacl) {
+      cflags += [ "-flto" ]
+
+      if (is_cfi) {
+        cfi_blacklist_path =
+            rebase_path("//tools/cfi/blacklist.txt", root_build_dir)
+        cflags += [
+          "-fsanitize=cfi-vcall",
+          "-fsanitize=cfi-derived-cast",
+          "-fsanitize=cfi-unrelated-cast",
+          "-fsanitize-blacklist=$cfi_blacklist_path",
+        ]
+      }
 
       if (use_cfi_diag) {
         cflags += [
           "-fno-sanitize-trap=cfi",
           "-fsanitize-recover=cfi",
           "-fno-inline-functions",
           "-fno-inline",
           "-fno-omit-frame-pointer",
           "-O1",
         ]
@@ skipping 16 matching lines @@
 
 config("default_sanitizer_coverage_flags") {
   cflags = []
 
   if (use_sanitizer_coverage) {
     # FIXME: make this configurable.
     cflags +=
         [ "-fsanitize-coverage=edge,indirect-calls,8bit-counters,trace-cmp" ]
   }
 }