Linux: Synchronize a few GN build flags with GYP.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 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/android/config.gni")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }
 if (is_posix) {
   import("//build/config/gcc/gcc_version.gni")
@@ skipping 150 matching lines @@
     }
 
     # CPU architecture. We may or may not be doing a cross compile now, so for
     # simplicity we always explicitly set the architecture.
     if (cpu_arch == "x64") {
       cflags += [ "-m64", "-march=x86-64", ]
       ldflags += [ "-m64" ]
     } else if (cpu_arch == "x86") {
       cflags += [ "-m32" ]
       ldflags += [ "-m32" ]
+      if (is_clang) {
+        cflags += [
+          # Else building libyuv gives clang's register allocator issues,
+          # see llvm.org/PR15798 / crbug.com/233709
+          "-momit-leaf-frame-pointer",
+          # Align the stack on 16-byte boundaries, http://crbug.com/418554.
+          "-mstack-alignment=16",
+          "-mstackrealign",
+        ]
+      }
     } else if (cpu_arch == "arm") {
       # Don't set the compiler flags for the WebView build. These will come
       # from the Android build system.
       if (!is_android_webview_build) {
         cflags += [
           "-march=$arm_arch",
           "-mfloat-abi=$arm_float_abi",
         ]
         if (arm_tune != "") {
           cflags += [ "-mtune=$arm_tune" ]
@@ skipping 65 matching lines @@
     gold_path = rebase_path("//third_party/binutils/Linux_x64/Release/bin",
                             root_build_dir)
     ldflags += [
       "-B$gold_path",
 
       # Newer gccs and clangs support -fuse-ld, use the flag to force gold
       # selection.
       # gcc -- http://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/Optimize-Options.html
       "-fuse-ld=gold",
 
-      # There seems to be a conflict of --icf and -pie in gold which can
-      # generate crashy binaries. As a security measure, -pie takes
-      # precedence for now.
       # TODO(brettw) common.gypi has this only for target toolset.
-      #"-Wl,--icf=safe",
-      "-Wl,--icf=none",
+      "-Wl,--icf=safe",
 
       # Experimentation found that using four linking threads
       # saved ~20% of link time.
       # https://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/281527606915bb36
       # Only apply this to the target linker, since the host
       # linker might not be gold, but isn't used much anyway.
       # TODO(raymes): Disable threading because gold is frequently
       # crashing on the bots: crbug.com/161942.
       #"-Wl,--threads",
       #"-Wl,--thread-count=4",
@@ skipping 665 matching lines @@
       cflags += [ "-gsplit-dwarf" ]
     }
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }