Revert of Clang toolchain: link Gold plugin with lld.

tools/clang/scripts/update.py

 #!/usr/bin/env python
 # 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.
 
 """This script is used to download prebuilt clang binaries.
 
 It is also used by package.py to build the prebuilt clang binaries."""
 
 import argparse
@@ skipping 51 matching lines @@
   COMPILER_RT_DIR = os.path.join(LLVM_DIR, 'compiler-rt')
 LIBCXX_DIR = os.path.join(LLVM_DIR, 'projects', 'libcxx')
 LIBCXXABI_DIR = os.path.join(LLVM_DIR, 'projects', 'libcxxabi')
 LLVM_BUILD_TOOLS_DIR = os.path.abspath(
     os.path.join(LLVM_DIR, '..', 'llvm-build-tools'))
 STAMP_FILE = os.path.normpath(
     os.path.join(LLVM_DIR, '..', 'llvm-build', 'cr_build_revision'))
 BINUTILS_DIR = os.path.join(THIRD_PARTY_DIR, 'binutils')
 BINUTILS_BIN_DIR = os.path.join(BINUTILS_DIR, BINUTILS_DIR,
                                 'Linux_x64', 'Release', 'bin')
+BFD_PLUGINS_DIR = os.path.join(BINUTILS_DIR, 'Linux_x64', 'Release',
+                               'lib', 'bfd-plugins')
 VERSION = '4.0.0'
 ANDROID_NDK_DIR = os.path.join(
     CHROMIUM_DIR, 'third_party', 'android_tools', 'ndk')
 
 # URL for pre-built binaries.
 CDS_URL = os.environ.get('CDS_CLANG_BUCKET_OVERRIDE',
     'https://commondatastorage.googleapis.com/chromium-browser-clang')
 
 LLVM_REPO_URL='https://llvm.org/svn/llvm-project'
 if 'LLVM_REPO_URL' in os.environ:
@@ skipping 466 matching lines @@
 
   # Build LLVM gold plugin with LTO. That speeds up the linker by ~10%.
   # We only use LTO for Linux now.
   if args.bootstrap and args.lto_gold_plugin:
     print 'Building LTO LLVM Gold plugin'
     if os.path.exists(LLVM_LTO_GOLD_PLUGIN_DIR):
       RmTree(LLVM_LTO_GOLD_PLUGIN_DIR)
     EnsureDirExists(LLVM_LTO_GOLD_PLUGIN_DIR)
     os.chdir(LLVM_LTO_GOLD_PLUGIN_DIR)
 
+    # Create a symlink to LLVMgold.so build in the previous step so that ar
+    # and ranlib could find it while linking LLVMgold.so with LTO.
+    EnsureDirExists(BFD_PLUGINS_DIR)
+    RunCommand(['ln', '-sf',
+                os.path.join(LLVM_BOOTSTRAP_INSTALL_DIR, 'lib', 'LLVMgold.so'),
+                os.path.join(BFD_PLUGINS_DIR, 'LLVMgold.so')])
+
     lto_cflags = ['-flto']
-    lto_ldflags = ['-fuse-ld=lld']
+    lto_ldflags = ['-fuse-ld=gold']
     if args.gcc_toolchain:
       # Tell the bootstrap compiler to use a specific gcc prefix to search
       # for standard library headers and shared object files.
       lto_cflags += ['--gcc-toolchain=' + args.gcc_toolchain]
     lto_cmake_args = base_cmake_args + [
         '-DLLVM_BINUTILS_INCDIR=' + binutils_incdir,
-        '-DCMAKE_AR=' + os.path.join(LLVM_BOOTSTRAP_INSTALL_DIR,
-                                     'bin', 'llvm-ar'),
-        '-DCMAKE_RANLIB=' + os.path.join(LLVM_BOOTSTRAP_INSTALL_DIR,
-                                         'bin', 'llvm-ranlib'),
-        '-DLLVM_ENABLE_LTO=ON',
         '-DCMAKE_C_COMPILER=' + cc,
         '-DCMAKE_CXX_COMPILER=' + cxx,
         '-DCMAKE_C_FLAGS=' + ' '.join(lto_cflags),
-        '-DCMAKE_CXX_FLAGS=' + ' '.join(lto_cflags + ['-std=c++11']),
+        '-DCMAKE_CXX_FLAGS=' + ' '.join(lto_cflags),
         '-DCMAKE_EXE_LINKER_FLAGS=' + ' '.join(lto_ldflags),
         '-DCMAKE_SHARED_LINKER_FLAGS=' + ' '.join(lto_ldflags),
         '-DCMAKE_MODULE_LINKER_FLAGS=' + ' '.join(lto_ldflags)]
 
+    # We need to use the proper binutils which support LLVM Gold plugin.
+    lto_env = os.environ.copy()
+    lto_env['PATH'] = BINUTILS_BIN_DIR + os.pathsep + lto_env.get('PATH', '')
+
     RmCmakeCache('.')
-    RunCommand(['cmake'] + lto_cmake_args + [LLVM_DIR])
-    RunCommand(['ninja', 'LLVMgold'])
+    RunCommand(['cmake'] + lto_cmake_args + [LLVM_DIR], env=lto_env)
+    RunCommand(['ninja', 'LLVMgold'], env=lto_env)
 
 
   # LLVM uses C++11 starting in llvm 3.5. On Linux, this means libstdc++4.7+ is
   # needed, on OS X it requires libc++. clang only automatically links to libc++
   # when targeting OS X 10.9+, so add stdlib=libc++ explicitly so clang can run
   # on OS X versions as old as 10.7.
   deployment_target = ''
 
   if sys.platform == 'darwin' and args.bootstrap:
     # When building on 10.9, /usr/include usually doesn't exist, and while
@@ skipping 303 matching lines @@
     args.force_local_build = True
     if 'OS=android' not in os.environ.get('GYP_DEFINES', ''):
       # Only build the Android ASan rt on ToT bots when targetting Android.
       args.with_android = False
 
   return UpdateClang(args)
 
 
 if __name__ == '__main__':
   sys.exit(main())