not working update.py to build fuchsia builtins

tools/clang/scripts/update.py

Index: tools/clang/scripts/update.py
diff --git a/tools/clang/scripts/update.py b/tools/clang/scripts/update.py
index 64c520700d6fb4ba016fe52a1ceff21bec9b49c2..dcf4e6f28bfd4d1027ad4ed17ed6137436aa4739 100755
--- a/tools/clang/scripts/update.py
+++ b/tools/clang/scripts/update.py
@@ -73,6 +73,7 @@ BFD_PLUGINS_DIR = os.path.join(BINUTILS_LIB_DIR, 'bfd-plugins')
 VERSION = '5.0.0'
 ANDROID_NDK_DIR = os.path.join(
     CHROMIUM_DIR, 'third_party', 'android_tools', 'ndk')
+FUCHSIA_SDK_DIR = os.path.join(CHROMIUM_DIR, 'third_party', 'fuchsia-sdk')
 
 # URL for pre-built binaries.
 CDS_URL = os.environ.get('CDS_CLANG_BUCKET_OVERRIDE',
@@ -448,6 +449,12 @@ def UpdateClang(args):
     print 'for how to install the NDK, or pass --without-android.'
     return 1
 
+  if args.with_fuchsia and not os.path.exists(FUCHSIA_SDK_DIR):
+    print 'Fuchsia SDK not found at ' + FUCHSIA_SDK_DIR
+    print 'Either install it there by including target_os=[\'fuchsia\'] in '
+    print '.gclient and rerunning gclient runhooks, or pass --without-fuchsia.'
+    return 1
+
   DownloadHostGcc(args)
   AddCMakeToPath()
   AddGnuWinToPath()
@@ -459,7 +466,7 @@ def UpdateClang(args):
   if sys.platform != 'darwin':
     Checkout('LLD', LLVM_REPO_URL + '/lld/trunk', LLD_DIR)
   elif os.path.exists(LLD_DIR):
-    # In case someone sends a tryjob that temporary adds lld to the checkout,
+    # In case someone sends a tryjob that temporarily adds lld to the checkout,
     # make sure it's not around on future builds.
     RmTree(LLD_DIR)
   Checkout('compiler-rt', LLVM_REPO_URL + '/compiler-rt/trunk', COMPILER_RT_DIR)
@@ -696,7 +703,7 @@ def UpdateClang(args):
   # Do a clobbered build due to cmake changes.
   if os.path.isdir(COMPILER_RT_BUILD_DIR):
     RmTree(COMPILER_RT_BUILD_DIR)
-  os.makedirs(COMPILER_RT_BUILD_DIR)
+  EnsureDirExists(COMPILER_RT_BUILD_DIR)
   os.chdir(COMPILER_RT_BUILD_DIR)
   # TODO(thakis): Add this once compiler-rt can build with clang-cl (see
   # above).
@@ -825,6 +832,32 @@ def UpdateClang(args):
         if runtime in files:
           shutil.copy(os.path.join(root, runtime), asan_rt_lib_dst_dir)
 
+  if args.with_fuchsia:
+    # TODO(fuchsia): There's no aarch64 sysroot in the SDK yet.
+    for target_arch in ('x86_64',):
+      build_dir = os.path.join(LLVM_BUILD_DIR, 'fuchsia-' + target_arch)
+      if not os.path.exists(build_dir):
+        os.mkdir(os.path.join(build_dir))
+      os.chdir(build_dir)
+      sysroot = '%s/sysroot/%s-fuchsia' % (FUCHSIA_SDK_DIR, target_arch)
+      cflags = ['--target=%s-fuchsia' % target_arch,
+                '--sysroot=' + sysroot]
+      fuchsia_args = base_cmake_args + [
+        '-DLLVM_ENABLE_THREADS=OFF',
+        '-DCMAKE_C_COMPILER=' + os.path.join(LLVM_BUILD_DIR, 'bin/clang'),
+        '-DCMAKE_CXX_COMPILER=' + os.path.join(LLVM_BUILD_DIR, 'bin/clang'),
+        '-DCMAKE_C_COMPILER_WORKS=ON',
+        '-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON',
+        '-DCMAKE_C_COMPILER_TARGET=%s-fuchsia-none' % target_arch,
+        '-DCMAKE_CXX_COMPILER_WORKS=ON',
+        '-DLLVM_CONFIG_PATH=' + os.path.join(LLVM_BUILD_DIR, 'bin/llvm-config'),
+        '-DCMAKE_C_FLAGS=' + ' '.join(cflags),
+        '-DCMAKE_CXX_FLAGS=' + ' '.join(cflags)]
+
+      RmCmakeCache('.')
+      RunCommand(['cmake'] + fuchsia_args + [COMPILER_RT_DIR])
+      RunCommand(['ninja', 'builtins'])
+
   # Run tests.
   if args.run_tests or use_head_revision:
     os.chdir(LLVM_BUILD_DIR)
@@ -847,7 +880,7 @@ def main():
   parser.add_argument('--if-needed', action='store_true',
                       help="run only if the script thinks clang is needed")
   parser.add_argument('--force-local-build', action='store_true',
-                      help="don't try to download prebuild binaries")
+                      help="don't try to download prebuilt binaries")
   parser.add_argument('--gcc-toolchain', help='set the version for which gcc '
                       'version be used for building; --gcc-toolchain=/opt/foo '
                       'picks /opt/foo/bin/gcc')
@@ -868,6 +901,10 @@ def main():
                       help='don\'t build Android ASan runtime (linux only)',
                       dest='with_android',
                       default=sys.platform.startswith('linux'))
+  parser.add_argument('--without-fuchsia', action='store_false',
+                      help='don\'t build Fuchsia runtime (linux only)',
+                      dest='with_fuchsia',
+                      default=sys.platform.startswith('linux'))
   args = parser.parse_args()
 
   if args.lto_gold_plugin and not args.bootstrap: