👻 Reland of Merge android's use_gold settings with the main use_gold GN arg logic

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")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/toolchain.gni")
@@ skipping 28 matching lines @@
   binutils_path = rebase_path("//third_party/binutils/Linux_x64/Release/bin",
                               root_build_dir)
 
   # Compile in such a way as to make it possible for the profiler to unwind full
   # stack frames. Setting this flag has a large effect on the performance of the
   # generated code than just setting profiling, but gives the profiler more
   # information to analyze.
   # Requires profiling to be set to true.
   enable_full_stack_frames_for_profiling = false
 
-  # Whether to use the gold linker from binutils instead of lld or bfd.
-  use_gold =
-      !use_lld && is_linux &&
-      (current_cpu == "x64" || current_cpu == "x86" || current_cpu == "arm")
-
   # When we are going to use gold we need to find it.
   # This is initialized below, after use_gold might have been overridden.
   gold_path = false
 
   # use_debug_fission: whether to use split DWARF debug info
   # files. This can reduce link time significantly, but is incompatible
   # with some utilities such as icecc and ccache. Requires gold and
   # gcc >= 4.8 or clang.
   # http://gcc.gnu.org/wiki/DebugFission
   #
@@ skipping 232 matching lines @@
     if (!using_sanitizer && !use_cfi_diag) {
       ldflags += [ "-Wl,-z,defs" ]
     }
   }
 
   # Linux-specific compiler flags setup.
   # ------------------------------------
   if (is_posix && use_lld && !is_nacl) {
     ldflags += [ "-fuse-ld=lld" ]
   } else if (use_gold) {
-    ldflags += [
-      "-B$gold_path",
+    ldflags += [ "-fuse-ld=gold" ]
+    if (is_android) {
+      if (is_clang) {
+        _rebased_android_toolchain_root =
+            rebase_path(android_toolchain_root, root_build_dir)
 
-      # 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",
+        # Let clang find the ld.gold in the NDK.
+        ldflags += [ "--gcc-toolchain=$_rebased_android_toolchain_root" ]
+      }
 
-      # 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",
-    ]
+      # Use -mstackrealign due to a bug on ia32 Jelly Bean.
+      # See crbug.com/521527
+      if (current_cpu == "x86") {
+        cflags += [ "-mstackrealign" ]
+      }
+    } else {
+      ldflags += [
+        "-B$gold_path",
+        # 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",
+      ]
+    }
 
     if (gdb_index) {
       ldflags += [ "-Wl,--gdb-index" ]
     }
 
     # TODO(thestig): Make this flag work with GN.
     #if (!is_official_build && !is_chromeos && !(is_asan || is_lsan || is_tsan || is_msan)) {
     #  ldflags += [
     #    "-Wl,--detect-odr-violations",
     #  ]
     #}
   } else if (linux_use_bundled_binutils) {
     # Gold is the default linker for the bundled binutils so we explicitly
     # enable the bfd linker when use_gold is not set.
     ldflags += [ "-fuse-ld=bfd" ]
+  } else if (is_android && current_cpu == "mipsel" && is_clang) {
+    # Let clang find the ld.bfd in the NDK.
+    _rebased_android_toolchain_root =
+        rebase_path(android_toolchain_root, root_build_dir)
+    ldflags += [ "--gcc-toolchain=$rebased_android_toolchain_root" ]
   }
 
   if (is_posix && (use_gold || (use_lld && !is_nacl)) && !using_sanitizer &&
       !(is_android && use_order_profiling)) {
     # TODO(crbug.com/576197) - gcc on x86 platforms + gold + icf=all
     # doesn't currently work. Once it does, use icf=all everywhere.
+    # Additionally, on Android x86 --icf=safe seems to cause issues as well.
     if (is_clang || (target_cpu != "x86" && target_cpu != "x64")) {
       ldflags += [ "-Wl,--icf=all" ]
-    } else {
+    } else if (!is_android) {
       ldflags += [ "-Wl,--icf=safe" ]
     }
   }
 
   if (linux_use_bundled_binutils) {
     cflags += [ "-B$binutils_path" ]
   }
 
   # Clang-specific compiler flags setup.
   # ------------------------------------
@@ skipping 1077 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }