Use -fuse-ld=gold when supported to select gold.

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 3817 matching lines @@
                       # There seems to be a conflict of --icf and -pie
                       # in gold which can generate crashy binaries. As
                       # a security measure, -pie takes precendence for
                       # now.
                       #'-Wl,--icf=safe',
                       '-Wl,--icf=none',
                     ],
                   }],
                 ],
               }],
+              # Newer gcc's support -fuse-ld, use the flag to force gold
+              # selection.
+              # gcc -- http://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/Optimize-Options.html
+              # clang support -- http://clang-developers.42468.n3.nabble.com/Adding-fuse-ld-support-to-clang-td4032180.html

[Nico, 2014/04/10 21:27:19]

That link is just a thread where someone posted a patch for this option, but the
patch didn't go anywhere and isn't committed. Remove this line. (gcc_version
isn't set for clang, so this isn't used, which is fine.)

…but does third_party/gold (referenced a few lines below, I suppose it says
third_party/binutils at trunk) contain a ld.gold? Else gcc won't use the gold in
-B but the system one, rigth?

[mithro-old, 2014/04/11 02:17:56]

Actually the patch did land and then was reverted. The guy said he would update
the thread when he relands the patch. Changed the comment to be clearer.
---------------
The code was committed and reverted, so if you want to have a go at fixing the
tests, you'd be welcome.  Otherwise, I'll hopefully get back to it in a few
weeks (although it's further down the list than tidying up a load of MIPS back
end fixes for upstreaming).
---------------
Yes, it does say binutils at trunk. I have rebased this patch and uploaded.

third_party/binutils does contain an ld.gold

With this patch, you can use "linux_use_gold_flags=1" and
"linux_use_gold_binary=0" to use the system gold linker (when using gcc 4.8).

+              ['gcc_version>=48', {
+                'cflags': [
+                  '-fuse-ld=gold',
+                ],
+                'ldflags': [
+                  '-fuse-ld=gold',
+                ],
+              }]
             ],
           }],
           ['linux_use_gold_binary==1', {
             'ldflags': [
               # Put our gold binary in the search path for the linker.
               # We pass the path to gold to the compiler.  gyp leaves
               # unspecified what the cwd is when running the compiler,
               # so the normal gyp path-munging fails us.  This hack
               # gets the right path.
               '-B<!(cd <(DEPTH) && pwd -P)/third_party/gold',
@@ skipping 1334 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',
   },
 }