Switch NCCL to build from open source (version 2.3.5-5) by default.

Note to users manually patching ptxas from a later toolkit version:
Building NCCL requires the same version of ptxas and nvlink.

PiperOrigin-RevId: 215911973

1 files changed, 1044 insertions, 935 deletions

diff --git a/third_party/gpus/cuda_configure.bzl b/third_party/gpus/cuda_configure.bzl
index 69f4599c16..831a3067b2 100644
--- a/third_party/gpus/cuda_configure.bzl
+++ b/third_party/gpus/cuda_configure.bzl
@@ -126,118 +126,141 @@ load(
 )
 
 def _get_python_bin(repository_ctx):
-    """Gets the python bin path."""
-    python_bin = repository_ctx.os.environ.get(_PYTHON_BIN_PATH)
-    if python_bin != None:
-        return python_bin
-    python_bin_name = "python.exe" if _is_windows(repository_ctx) else "python"
-    python_bin_path = repository_ctx.which(python_bin_name)
-    if python_bin_path != None:
-        return str(python_bin_path)
-    auto_configure_fail("Cannot find python in PATH, please make sure " +
-                        "python is installed and add its directory in PATH, or --define " +
-                        "%s='/something/else'.\nPATH=%s" % (
-                            _PYTHON_BIN_PATH,
-                            repository_ctx.os.environ.get("PATH", ""),
-                        ))
+  """Gets the python bin path."""
+  python_bin = repository_ctx.os.environ.get(_PYTHON_BIN_PATH)
+  if python_bin != None:
+    return python_bin
+  python_bin_name = "python.exe" if _is_windows(repository_ctx) else "python"
+  python_bin_path = repository_ctx.which(python_bin_name)
+  if python_bin_path != None:
+    return str(python_bin_path)
+  auto_configure_fail(
+      "Cannot find python in PATH, please make sure " +
+      "python is installed and add its directory in PATH, or --define " +
+      "%s='/something/else'.\nPATH=%s" % (
+          _PYTHON_BIN_PATH,
+          repository_ctx.os.environ.get("PATH", ""),
+      ))
+
 
 def _get_nvcc_tmp_dir_for_windows(repository_ctx):
-    """Return the tmp directory for nvcc to generate intermediate source files."""
-    escaped_tmp_dir = escape_string(
-        get_env_var(repository_ctx, "TMP", "C:\\Windows\\Temp").replace("\\", "\\\\"),
-    )
-    return escaped_tmp_dir + "\\\\nvcc_inter_files_tmp_dir"
+  """Return the tmp directory for nvcc to generate intermediate source files."""
+  escaped_tmp_dir = escape_string(
+      get_env_var(repository_ctx, "TMP", "C:\\Windows\\Temp").replace(
+          "\\", "\\\\"),)
+  return escaped_tmp_dir + "\\\\nvcc_inter_files_tmp_dir"
 
-def _get_msvc_compiler(repository_ctx):
-    vc_path = find_vc_path(repository_ctx)
-    return find_msvc_tool(repository_ctx, vc_path, "cl.exe").replace("\\", "/")
 
-def _get_win_cuda_defines(repository_ctx):
-    """Return CROSSTOOL defines for Windows"""
-
-    # If we are not on Windows, return empty vaules for Windows specific fields.
-    # This ensures the CROSSTOOL file parser is happy.
-    if not _is_windows(repository_ctx):
-        return {
-            "%{msvc_env_tmp}": "",
-            "%{msvc_env_path}": "",
-            "%{msvc_env_include}": "",
-            "%{msvc_env_lib}": "",
-            "%{msvc_cl_path}": "",
-            "%{msvc_ml_path}": "",
-            "%{msvc_link_path}": "",
-            "%{msvc_lib_path}": "",
-            "%{cxx_builtin_include_directory}": "",
-        }
-
-    vc_path = find_vc_path(repository_ctx)
-    if not vc_path:
-        auto_configure_fail("Visual C++ build tools not found on your machine." +
-                            "Please check your installation following https://docs.bazel.build/versions/master/windows.html#using")
-        return {}
-
-    env = setup_vc_env_vars(repository_ctx, vc_path)
-    escaped_paths = escape_string(env["PATH"])
-    escaped_include_paths = escape_string(env["INCLUDE"])
-    escaped_lib_paths = escape_string(env["LIB"])
-    escaped_tmp_dir = escape_string(
-        get_env_var(repository_ctx, "TMP", "C:\\Windows\\Temp").replace("\\", "\\\\"),
-    )
+def _get_msvc_compiler(repository_ctx):
+  vc_path = find_vc_path(repository_ctx)
+  return find_msvc_tool(repository_ctx, vc_path, "cl.exe").replace("\\", "/")
 
-    msvc_cl_path = "windows/msvc_wrapper_for_nvcc.bat"
-    msvc_ml_path = find_msvc_tool(repository_ctx, vc_path, "ml64.exe").replace("\\", "/")
-    msvc_link_path = find_msvc_tool(repository_ctx, vc_path, "link.exe").replace("\\", "/")
-    msvc_lib_path = find_msvc_tool(repository_ctx, vc_path, "lib.exe").replace("\\", "/")
 
-    # nvcc will generate some temporary source files under %{nvcc_tmp_dir}
-    # The generated files are guranteed to have unique name, so they can share the same tmp directory
-    escaped_cxx_include_directories = ["cxx_builtin_include_directory: \"%s\"" % _get_nvcc_tmp_dir_for_windows(repository_ctx)]
-    for path in escaped_include_paths.split(";"):
-        if path:
-            escaped_cxx_include_directories.append("cxx_builtin_include_directory: \"%s\"" % path)
+def _get_win_cuda_defines(repository_ctx):
+  """Return CROSSTOOL defines for Windows"""
 
+  # If we are not on Windows, return empty vaules for Windows specific fields.
+  # This ensures the CROSSTOOL file parser is happy.
+  if not _is_windows(repository_ctx):
     return {
-        "%{msvc_env_tmp}": escaped_tmp_dir,
-        "%{msvc_env_path}": escaped_paths,
-        "%{msvc_env_include}": escaped_include_paths,
-        "%{msvc_env_lib}": escaped_lib_paths,
-        "%{msvc_cl_path}": msvc_cl_path,
-        "%{msvc_ml_path}": msvc_ml_path,
-        "%{msvc_link_path}": msvc_link_path,
-        "%{msvc_lib_path}": msvc_lib_path,
-        "%{cxx_builtin_include_directory}": "\n".join(escaped_cxx_include_directories),
+        "%{msvc_env_tmp}": "",
+        "%{msvc_env_path}": "",
+        "%{msvc_env_include}": "",
+        "%{msvc_env_lib}": "",
+        "%{msvc_cl_path}": "",
+        "%{msvc_ml_path}": "",
+        "%{msvc_link_path}": "",
+        "%{msvc_lib_path}": "",
+        "%{cxx_builtin_include_directory}": "",
     }
 
+  vc_path = find_vc_path(repository_ctx)
+  if not vc_path:
+    auto_configure_fail(
+        "Visual C++ build tools not found on your machine." +
+        "Please check your installation following https://docs.bazel.build/versions/master/windows.html#using"
+    )
+    return {}
+
+  env = setup_vc_env_vars(repository_ctx, vc_path)
+  escaped_paths = escape_string(env["PATH"])
+  escaped_include_paths = escape_string(env["INCLUDE"])
+  escaped_lib_paths = escape_string(env["LIB"])
+  escaped_tmp_dir = escape_string(
+      get_env_var(repository_ctx, "TMP", "C:\\Windows\\Temp").replace(
+          "\\", "\\\\"),)
+
+  msvc_cl_path = "windows/msvc_wrapper_for_nvcc.bat"
+  msvc_ml_path = find_msvc_tool(repository_ctx, vc_path, "ml64.exe").replace(
+      "\\", "/")
+  msvc_link_path = find_msvc_tool(repository_ctx, vc_path, "link.exe").replace(
+      "\\", "/")
+  msvc_lib_path = find_msvc_tool(repository_ctx, vc_path, "lib.exe").replace(
+      "\\", "/")
+
+  # nvcc will generate some temporary source files under %{nvcc_tmp_dir}
+  # The generated files are guranteed to have unique name, so they can share the same tmp directory
+  escaped_cxx_include_directories = [
+      "cxx_builtin_include_directory: \"%s\"" %
+      _get_nvcc_tmp_dir_for_windows(repository_ctx)
+  ]
+  for path in escaped_include_paths.split(";"):
+    if path:
+      escaped_cxx_include_directories.append(
+          "cxx_builtin_include_directory: \"%s\"" % path)
+
+  return {
+      "%{msvc_env_tmp}":
+          escaped_tmp_dir,
+      "%{msvc_env_path}":
+          escaped_paths,
+      "%{msvc_env_include}":
+          escaped_include_paths,
+      "%{msvc_env_lib}":
+          escaped_lib_paths,
+      "%{msvc_cl_path}":
+          msvc_cl_path,
+      "%{msvc_ml_path}":
+          msvc_ml_path,
+      "%{msvc_link_path}":
+          msvc_link_path,
+      "%{msvc_lib_path}":
+          msvc_lib_path,
+      "%{cxx_builtin_include_directory}":
+          "\n".join(escaped_cxx_include_directories),
+  }
+
 # TODO(dzc): Once these functions have been factored out of Bazel's
 # cc_configure.bzl, load them from @bazel_tools instead.
 # BEGIN cc_configure common functions.
 def find_cc(repository_ctx):
-    """Find the C++ compiler."""
-    if _is_windows(repository_ctx):
-        return _get_msvc_compiler(repository_ctx)
-
-    if _use_cuda_clang(repository_ctx):
-        target_cc_name = "clang"
-        cc_path_envvar = _CLANG_CUDA_COMPILER_PATH
-        if _flag_enabled(repository_ctx, _TF_DOWNLOAD_CLANG):
-            return "extra_tools/bin/clang"
-    else:
-        target_cc_name = "gcc"
-        cc_path_envvar = _GCC_HOST_COMPILER_PATH
-    cc_name = target_cc_name
-
-    if cc_path_envvar in repository_ctx.os.environ:
-        cc_name_from_env = repository_ctx.os.environ[cc_path_envvar].strip()
-        if cc_name_from_env:
-            cc_name = cc_name_from_env
-    if cc_name.startswith("/"):
-        # Absolute path, maybe we should make this supported by our which function.
-        return cc_name
-    cc = repository_ctx.which(cc_name)
-    if cc == None:
-        fail(("Cannot find {}, either correct your path or set the {}" +
-              " environment variable").format(target_cc_name, cc_path_envvar))
-    return cc
+  """Find the C++ compiler."""
+  if _is_windows(repository_ctx):
+    return _get_msvc_compiler(repository_ctx)
+
+  if _use_cuda_clang(repository_ctx):
+    target_cc_name = "clang"
+    cc_path_envvar = _CLANG_CUDA_COMPILER_PATH
+    if _flag_enabled(repository_ctx, _TF_DOWNLOAD_CLANG):
+      return "extra_tools/bin/clang"
+  else:
+    target_cc_name = "gcc"
+    cc_path_envvar = _GCC_HOST_COMPILER_PATH
+  cc_name = target_cc_name
+
+  if cc_path_envvar in repository_ctx.os.environ:
+    cc_name_from_env = repository_ctx.os.environ[cc_path_envvar].strip()
+    if cc_name_from_env:
+      cc_name = cc_name_from_env
+  if cc_name.startswith("/"):
+    # Absolute path, maybe we should make this supported by our which function.
+    return cc_name
+  cc = repository_ctx.which(cc_name)
+  if cc == None:
+    fail(("Cannot find {}, either correct your path or set the {}" +
+          " environment variable").format(target_cc_name, cc_path_envvar))
+  return cc
+
 
 _INC_DIR_MARKER_BEGIN = "#include <...>"
 
@@ -246,80 +269,82 @@ _OSX_FRAMEWORK_SUFFIX = " (framework directory)"
 _OSX_FRAMEWORK_SUFFIX_LEN = len(_OSX_FRAMEWORK_SUFFIX)
 
 def _cxx_inc_convert(path):
-    """Convert path returned by cc -E xc++ in a complete path."""
-    path = path.strip()
-    if path.endswith(_OSX_FRAMEWORK_SUFFIX):
-        path = path[:-_OSX_FRAMEWORK_SUFFIX_LEN].strip()
-    return path
+  """Convert path returned by cc -E xc++ in a complete path."""
+  path = path.strip()
+  if path.endswith(_OSX_FRAMEWORK_SUFFIX):
+    path = path[:-_OSX_FRAMEWORK_SUFFIX_LEN].strip()
+  return path
+
 
 def _normalize_include_path(repository_ctx, path):
-    """Normalizes include paths before writing them to the crosstool.
+  """Normalizes include paths before writing them to the crosstool.
 
     If path points inside the 'crosstool' folder of the repository, a relative
     path is returned.
     If path points outside the 'crosstool' folder, an absolute path is returned.
     """
-    path = str(repository_ctx.path(path))
-    crosstool_folder = str(repository_ctx.path(".").get_child("crosstool"))
+  path = str(repository_ctx.path(path))
+  crosstool_folder = str(repository_ctx.path(".").get_child("crosstool"))
+
+  if path.startswith(crosstool_folder):
+    # We drop the path to "$REPO/crosstool" and a trailing path separator.
+    return path[len(crosstool_folder) + 1:]
+  return path
 
-    if path.startswith(crosstool_folder):
-        # We drop the path to "$REPO/crosstool" and a trailing path separator.
-        return path[len(crosstool_folder) + 1:]
-    return path
 
 def _get_cxx_inc_directories_impl(repository_ctx, cc, lang_is_cpp):
-    """Compute the list of default C or C++ include directories."""
-    if lang_is_cpp:
-        lang = "c++"
-    else:
-        lang = "c"
-    result = repository_ctx.execute([cc, "-E", "-x" + lang, "-", "-v"])
-    index1 = result.stderr.find(_INC_DIR_MARKER_BEGIN)
-    if index1 == -1:
-        return []
-    index1 = result.stderr.find("\n", index1)
-    if index1 == -1:
-        return []
-    index2 = result.stderr.rfind("\n ")
-    if index2 == -1 or index2 < index1:
-        return []
-    index2 = result.stderr.find("\n", index2 + 1)
-    if index2 == -1:
-        inc_dirs = result.stderr[index1 + 1:]
-    else:
-        inc_dirs = result.stderr[index1 + 1:index2].strip()
+  """Compute the list of default C or C++ include directories."""
+  if lang_is_cpp:
+    lang = "c++"
+  else:
+    lang = "c"
+  result = repository_ctx.execute([cc, "-E", "-x" + lang, "-", "-v"])
+  index1 = result.stderr.find(_INC_DIR_MARKER_BEGIN)
+  if index1 == -1:
+    return []
+  index1 = result.stderr.find("\n", index1)
+  if index1 == -1:
+    return []
+  index2 = result.stderr.rfind("\n ")
+  if index2 == -1 or index2 < index1:
+    return []
+  index2 = result.stderr.find("\n", index2 + 1)
+  if index2 == -1:
+    inc_dirs = result.stderr[index1 + 1:]
+  else:
+    inc_dirs = result.stderr[index1 + 1:index2].strip()
+
+  return [
+      _normalize_include_path(repository_ctx, _cxx_inc_convert(p))
+      for p in inc_dirs.split("\n")
+  ]
 
-    return [
-        _normalize_include_path(repository_ctx, _cxx_inc_convert(p))
-        for p in inc_dirs.split("\n")
-    ]
 
 def get_cxx_inc_directories(repository_ctx, cc):
-    """Compute the list of default C and C++ include directories."""
-
-    # For some reason `clang -xc` sometimes returns include paths that are
-    # different from the ones from `clang -xc++`. (Symlink and a dir)
-    # So we run the compiler with both `-xc` and `-xc++` and merge resulting lists
-    includes_cpp = _get_cxx_inc_directories_impl(repository_ctx, cc, True)
-    includes_c = _get_cxx_inc_directories_impl(repository_ctx, cc, False)
-
-    includes_cpp_set = depset(includes_cpp)
-    return includes_cpp + [
-        inc
-        for inc in includes_c
-        if inc not in includes_cpp_set
-    ]
+  """Compute the list of default C and C++ include directories."""
+
+  # For some reason `clang -xc` sometimes returns include paths that are
+  # different from the ones from `clang -xc++`. (Symlink and a dir)
+  # So we run the compiler with both `-xc` and `-xc++` and merge resulting lists
+  includes_cpp = _get_cxx_inc_directories_impl(repository_ctx, cc, True)
+  includes_c = _get_cxx_inc_directories_impl(repository_ctx, cc, False)
+
+  includes_cpp_set = depset(includes_cpp)
+  return includes_cpp + [
+      inc for inc in includes_c if inc not in includes_cpp_set
+  ]
+
 
 def auto_configure_fail(msg):
-    """Output failure message when cuda configuration fails."""
-    red = "\033[0;31m"
-    no_color = "\033[0m"
-    fail("\n%sCuda Configuration Error:%s %s\n" % (red, no_color, msg))
+  """Output failure message when cuda configuration fails."""
+  red = "\033[0;31m"
+  no_color = "\033[0m"
+  fail("\n%sCuda Configuration Error:%s %s\n" % (red, no_color, msg))
 
 # END cc_configure common functions (see TODO above).
 
 def _host_compiler_includes(repository_ctx, cc):
-    """Generates the cxx_builtin_include_directory entries for gcc inc dirs.
+  """Generates the cxx_builtin_include_directory entries for gcc inc dirs.
 
     Args:
       repository_ctx: The repository context.
@@ -330,14 +355,15 @@ def _host_compiler_includes(repository_ctx, cc):
       host compiler include directories, which can be added to the CROSSTOOL
       file.
     """
-    inc_dirs = get_cxx_inc_directories(repository_ctx, cc)
-    inc_entries = []
-    for inc_dir in inc_dirs:
-        inc_entries.append("  cxx_builtin_include_directory: \"%s\"" % inc_dir)
-    return "\n".join(inc_entries)
+  inc_dirs = get_cxx_inc_directories(repository_ctx, cc)
+  inc_entries = []
+  for inc_dir in inc_dirs:
+    inc_entries.append("  cxx_builtin_include_directory: \"%s\"" % inc_dir)
+  return "\n".join(inc_entries)
+
 
 def _cuda_include_path(repository_ctx, cuda_config):
-    """Generates the cxx_builtin_include_directory entries for cuda inc dirs.
+  """Generates the cxx_builtin_include_directory entries for cuda inc dirs.
 
     Args:
       repository_ctx: The repository context.
@@ -348,39 +374,41 @@ def _cuda_include_path(repository_ctx, cuda_config):
       host compiler include directories, which can be added to the CROSSTOOL
       file.
     """
-    nvcc_path = repository_ctx.path("%s/bin/nvcc%s" %
-                                    (
-                                        cuda_config.cuda_toolkit_path,
-                                        ".exe" if cuda_config.cpu_value == "Windows" else "",
-                                    ))
-    result = repository_ctx.execute([
-        nvcc_path,
-        "-v",
-        "/dev/null",
-        "-o",
-        "/dev/null",
-    ])
-    target_dir = ""
-    for one_line in result.stderr.splitlines():
-        if one_line.startswith("#$ _TARGET_DIR_="):
-            target_dir = (cuda_config.cuda_toolkit_path + "/" +
-                          one_line.replace("#$ _TARGET_DIR_=", "") + "/include")
-    inc_entries = []
-    if target_dir != "":
-        inc_entries.append("  cxx_builtin_include_directory: \"%s\"" % target_dir)
-    default_include = cuda_config.cuda_toolkit_path + "/include"
-    inc_entries.append("  cxx_builtin_include_directory: \"%s\"" %
-                       default_include)
-    return "\n".join(inc_entries)
+  nvcc_path = repository_ctx.path("%s/bin/nvcc%s" % (
+      cuda_config.cuda_toolkit_path,
+      ".exe" if cuda_config.cpu_value == "Windows" else "",
+  ))
+  result = repository_ctx.execute([
+      nvcc_path,
+      "-v",
+      "/dev/null",
+      "-o",
+      "/dev/null",
+  ])
+  target_dir = ""
+  for one_line in result.stderr.splitlines():
+    if one_line.startswith("#$ _TARGET_DIR_="):
+      target_dir = (
+          cuda_config.cuda_toolkit_path + "/" + one_line.replace(
+              "#$ _TARGET_DIR_=", "") + "/include")
+  inc_entries = []
+  if target_dir != "":
+    inc_entries.append("  cxx_builtin_include_directory: \"%s\"" % target_dir)
+  default_include = cuda_config.cuda_toolkit_path + "/include"
+  inc_entries.append(
+      "  cxx_builtin_include_directory: \"%s\"" % default_include)
+  return "\n".join(inc_entries)
+
 
 def _enable_cuda(repository_ctx):
-    if "TF_NEED_CUDA" in repository_ctx.os.environ:
-        enable_cuda = repository_ctx.os.environ["TF_NEED_CUDA"].strip()
-        return enable_cuda == "1"
-    return False
+  if "TF_NEED_CUDA" in repository_ctx.os.environ:
+    enable_cuda = repository_ctx.os.environ["TF_NEED_CUDA"].strip()
+    return enable_cuda == "1"
+  return False
+
 
-def _cuda_toolkit_path(repository_ctx):
-    """Finds the cuda toolkit directory.
+def cuda_toolkit_path(repository_ctx):
+  """Finds the cuda toolkit directory.
 
     Args:
       repository_ctx: The repository context.
@@ -388,27 +416,31 @@ def _cuda_toolkit_path(repository_ctx):
     Returns:
       A speculative real path of the cuda toolkit install directory.
     """
-    cuda_toolkit_path = _DEFAULT_CUDA_TOOLKIT_PATH
-    if _CUDA_TOOLKIT_PATH in repository_ctx.os.environ:
-        cuda_toolkit_path = repository_ctx.os.environ[_CUDA_TOOLKIT_PATH].strip()
-    if not repository_ctx.path(cuda_toolkit_path).exists:
-        auto_configure_fail("Cannot find cuda toolkit path.")
-    return str(repository_ctx.path(cuda_toolkit_path).realpath)
+  cuda_toolkit_path = _DEFAULT_CUDA_TOOLKIT_PATH
+  if _CUDA_TOOLKIT_PATH in repository_ctx.os.environ:
+    cuda_toolkit_path = repository_ctx.os.environ[_CUDA_TOOLKIT_PATH].strip()
+  if not repository_ctx.path(cuda_toolkit_path).exists:
+    auto_configure_fail("Cannot find cuda toolkit path.")
+  return str(repository_ctx.path(cuda_toolkit_path).realpath)
+
 
 def _cudnn_install_basedir(repository_ctx):
-    """Finds the cudnn install directory."""
-    cudnn_install_path = _DEFAULT_CUDNN_INSTALL_PATH
-    if _CUDNN_INSTALL_PATH in repository_ctx.os.environ:
-        cudnn_install_path = repository_ctx.os.environ[_CUDNN_INSTALL_PATH].strip()
-    if not repository_ctx.path(cudnn_install_path).exists:
-        auto_configure_fail("Cannot find cudnn install path.")
-    return cudnn_install_path
+  """Finds the cudnn install directory."""
+  cudnn_install_path = _DEFAULT_CUDNN_INSTALL_PATH
+  if _CUDNN_INSTALL_PATH in repository_ctx.os.environ:
+    cudnn_install_path = repository_ctx.os.environ[_CUDNN_INSTALL_PATH].strip()
+  if not repository_ctx.path(cudnn_install_path).exists:
+    auto_configure_fail("Cannot find cudnn install path.")
+  return cudnn_install_path
+
 
 def matches_version(environ_version, detected_version):
-    """Checks whether the user-specified version matches the detected version.
+  """Checks whether the user-specified version matches the detected version.
 
-    This function performs a weak matching so that if the user specifies only the
-    major or major and minor versions, the versions are still considered matching
+    This function performs a weak matching so that if the user specifies only
+    the
+    major or major and minor versions, the versions are still considered
+    matching
     if the version parts match. To illustrate:
 
         environ_version  detected_version  result
@@ -424,25 +456,25 @@ def matches_version(environ_version, detected_version):
         variables.
       detected_version: The version autodetected from the CUDA installation on
         the system.
-
     Returns: True if user-specified version matches detected version and False
       otherwise.
-    """
-    environ_version_parts = environ_version.split(".")
-    detected_version_parts = detected_version.split(".")
-    if len(detected_version_parts) < len(environ_version_parts):
-        return False
-    for i, part in enumerate(detected_version_parts):
-        if i >= len(environ_version_parts):
-            break
-        if part != environ_version_parts[i]:
-            return False
-    return True
+  """
+  environ_version_parts = environ_version.split(".")
+  detected_version_parts = detected_version.split(".")
+  if len(detected_version_parts) < len(environ_version_parts):
+    return False
+  for i, part in enumerate(detected_version_parts):
+    if i >= len(environ_version_parts):
+      break
+    if part != environ_version_parts[i]:
+      return False
+  return True
+
 
 _NVCC_VERSION_PREFIX = "Cuda compilation tools, release "
 
 def _cuda_version(repository_ctx, cuda_toolkit_path, cpu_value):
-    """Detects the version of CUDA installed on the system.
+  """Detects the version of CUDA installed on the system.
 
     Args:
       repository_ctx: The repository context.
@@ -452,64 +484,61 @@ def _cuda_version(repository_ctx, cuda_toolkit_path, cpu_value):
       String containing the version of CUDA.
     """
 
-    # Run nvcc --version and find the line containing the CUDA version.
-    nvcc_path = repository_ctx.path("%s/bin/nvcc%s" %
-                                    (
-                                        cuda_toolkit_path,
-                                        ".exe" if cpu_value == "Windows" else "",
-                                    ))
-    if not nvcc_path.exists:
-        auto_configure_fail("Cannot find nvcc at %s" % str(nvcc_path))
-    result = repository_ctx.execute([str(nvcc_path), "--version"])
-    if result.stderr:
-        auto_configure_fail("Error running nvcc --version: %s" % result.stderr)
-    lines = result.stdout.splitlines()
-    version_line = lines[len(lines) - 1]
-    if version_line.find(_NVCC_VERSION_PREFIX) == -1:
-        auto_configure_fail(
-            "Could not parse CUDA version from nvcc --version. Got: %s" %
-            result.stdout,
-        )
-
-    # Parse the CUDA version from the line containing the CUDA version.
-    prefix_removed = version_line.replace(_NVCC_VERSION_PREFIX, "")
-    parts = prefix_removed.split(",")
-    if len(parts) != 2 or len(parts[0]) < 2:
-        auto_configure_fail(
-            "Could not parse CUDA version from nvcc --version. Got: %s" %
-            result.stdout,
-        )
-    full_version = parts[1].strip()
-    if full_version.startswith("V"):
-        full_version = full_version[1:]
-
-    # Check whether TF_CUDA_VERSION was set by the user and fail if it does not
-    # match the detected version.
-    environ_version = ""
-    if _TF_CUDA_VERSION in repository_ctx.os.environ:
-        environ_version = repository_ctx.os.environ[_TF_CUDA_VERSION].strip()
-    if environ_version and not matches_version(environ_version, full_version):
-        auto_configure_fail(
-            ("CUDA version detected from nvcc (%s) does not match " +
-             "TF_CUDA_VERSION (%s)") % (full_version, environ_version),
-        )
-
-    # We only use the version consisting of the major and minor version numbers.
-    version_parts = full_version.split(".")
-    if len(version_parts) < 2:
-        auto_configure_fail("CUDA version detected from nvcc (%s) is incomplete.")
-    if cpu_value == "Windows":
-        version = "64_%s%s" % (version_parts[0], version_parts[1])
-    else:
-        version = "%s.%s" % (version_parts[0], version_parts[1])
-    return version
+  # Run nvcc --version and find the line containing the CUDA version.
+  nvcc_path = repository_ctx.path("%s/bin/nvcc%s" % (
+      cuda_toolkit_path,
+      ".exe" if cpu_value == "Windows" else "",
+  ))
+  if not nvcc_path.exists:
+    auto_configure_fail("Cannot find nvcc at %s" % str(nvcc_path))
+  result = repository_ctx.execute([str(nvcc_path), "--version"])
+  if result.stderr:
+    auto_configure_fail("Error running nvcc --version: %s" % result.stderr)
+  lines = result.stdout.splitlines()
+  version_line = lines[len(lines) - 1]
+  if version_line.find(_NVCC_VERSION_PREFIX) == -1:
+    auto_configure_fail(
+        "Could not parse CUDA version from nvcc --version. Got: %s" %
+        result.stdout,)
+
+  # Parse the CUDA version from the line containing the CUDA version.
+  prefix_removed = version_line.replace(_NVCC_VERSION_PREFIX, "")
+  parts = prefix_removed.split(",")
+  if len(parts) != 2 or len(parts[0]) < 2:
+    auto_configure_fail(
+        "Could not parse CUDA version from nvcc --version. Got: %s" %
+        result.stdout,)
+  full_version = parts[1].strip()
+  if full_version.startswith("V"):
+    full_version = full_version[1:]
+
+  # Check whether TF_CUDA_VERSION was set by the user and fail if it does not
+  # match the detected version.
+  environ_version = ""
+  if _TF_CUDA_VERSION in repository_ctx.os.environ:
+    environ_version = repository_ctx.os.environ[_TF_CUDA_VERSION].strip()
+  if environ_version and not matches_version(environ_version, full_version):
+    auto_configure_fail(
+        ("CUDA version detected from nvcc (%s) does not match " +
+         "TF_CUDA_VERSION (%s)") % (full_version, environ_version),)
+
+  # We only use the version consisting of the major and minor version numbers.
+  version_parts = full_version.split(".")
+  if len(version_parts) < 2:
+    auto_configure_fail("CUDA version detected from nvcc (%s) is incomplete.")
+  if cpu_value == "Windows":
+    version = "64_%s%s" % (version_parts[0], version_parts[1])
+  else:
+    version = "%s.%s" % (version_parts[0], version_parts[1])
+  return version
+
 
 _DEFINE_CUDNN_MAJOR = "#define CUDNN_MAJOR"
 _DEFINE_CUDNN_MINOR = "#define CUDNN_MINOR"
 _DEFINE_CUDNN_PATCHLEVEL = "#define CUDNN_PATCHLEVEL"
 
 def find_cuda_define(repository_ctx, header_dir, header_file, define):
-    """Returns the value of a #define in a header file.
+  """Returns the value of a #define in a header file.
 
     Greps through a header file and returns the value of the specified #define.
     If the #define is not found, then raise an error.
@@ -524,52 +553,52 @@ def find_cuda_define(repository_ctx, header_dir, header_file, define):
       The value of the #define found in the header.
     """
 
-    # Confirm location of the header and grep for the line defining the macro.
-    h_path = repository_ctx.path("%s/%s" % (header_dir, header_file))
-    if not h_path.exists:
-        auto_configure_fail("Cannot find %s at %s" % (header_file, str(h_path)))
-    result = repository_ctx.execute(
-        # Grep one more lines as some #defines are splitted into two lines.
-        ["grep", "--color=never", "-A1", "-E", define, str(h_path)],
-    )
-    if result.stderr:
-        auto_configure_fail("Error reading %s: %s" % (str(h_path), result.stderr))
-
-    # Parse the version from the line defining the macro.
-    if result.stdout.find(define) == -1:
-        auto_configure_fail("Cannot find line containing '%s' in %s" %
-                            (define, h_path))
-
-    # Split results to lines
-    lines = result.stdout.split("\n")
-    num_lines = len(lines)
-    for l in range(num_lines):
-        line = lines[l]
-        if define in line:  # Find the line with define
-            version = line
-            if l != num_lines - 1 and line[-1] == "\\":  # Add next line, if multiline
-                version = version[:-1] + lines[l + 1]
-            break
-
-    # Remove any comments
-    version = version.split("//")[0]
-
-    # Remove define name
-    version = version.replace(define, "").strip()
-
-    # Remove the code after the version number.
-    version_end = version.find(" ")
-    if version_end != -1:
-        if version_end == 0:
-            auto_configure_fail(
-                "Cannot extract the version from line containing '%s' in %s" %
-                (define, str(h_path)),
-            )
-        version = version[:version_end].strip()
-    return version
+  # Confirm location of the header and grep for the line defining the macro.
+  h_path = repository_ctx.path("%s/%s" % (header_dir, header_file))
+  if not h_path.exists:
+    auto_configure_fail("Cannot find %s at %s" % (header_file, str(h_path)))
+  result = repository_ctx.execute(
+      # Grep one more lines as some #defines are splitted into two lines.
+      ["grep", "--color=never", "-A1", "-E", define,
+       str(h_path)],)
+  if result.stderr:
+    auto_configure_fail("Error reading %s: %s" % (str(h_path), result.stderr))
+
+  # Parse the version from the line defining the macro.
+  if result.stdout.find(define) == -1:
+    auto_configure_fail(
+        "Cannot find line containing '%s' in %s" % (define, h_path))
+
+  # Split results to lines
+  lines = result.stdout.split("\n")
+  num_lines = len(lines)
+  for l in range(num_lines):
+    line = lines[l]
+    if define in line:  # Find the line with define
+      version = line
+      if l != num_lines - 1 and line[-1] == "\\":  # Add next line, if multiline
+        version = version[:-1] + lines[l + 1]
+      break
+
+  # Remove any comments
+  version = version.split("//")[0]
+
+  # Remove define name
+  version = version.replace(define, "").strip()
+
+  # Remove the code after the version number.
+  version_end = version.find(" ")
+  if version_end != -1:
+    if version_end == 0:
+      auto_configure_fail(
+          "Cannot extract the version from line containing '%s' in %s" %
+          (define, str(h_path)),)
+    version = version[:version_end].strip()
+  return version
+
 
 def _cudnn_version(repository_ctx, cudnn_install_basedir, cpu_value):
-    """Detects the version of cuDNN installed on the system.
+  """Detects the version of cuDNN installed on the system.
 
     Args:
       repository_ctx: The repository context.
@@ -579,68 +608,68 @@ def _cudnn_version(repository_ctx, cudnn_install_basedir, cpu_value):
     Returns:
       A string containing the version of cuDNN.
     """
-    cudnn_header_dir = _find_cudnn_header_dir(
-        repository_ctx,
-        cudnn_install_basedir,
-    )
-    major_version = find_cuda_define(
-        repository_ctx,
-        cudnn_header_dir,
-        "cudnn.h",
-        _DEFINE_CUDNN_MAJOR,
-    )
-    minor_version = find_cuda_define(
-        repository_ctx,
-        cudnn_header_dir,
-        "cudnn.h",
-        _DEFINE_CUDNN_MINOR,
-    )
-    patch_version = find_cuda_define(
-        repository_ctx,
-        cudnn_header_dir,
-        "cudnn.h",
-        _DEFINE_CUDNN_PATCHLEVEL,
-    )
-    full_version = "%s.%s.%s" % (major_version, minor_version, patch_version)
-
-    # Check whether TF_CUDNN_VERSION was set by the user and fail if it does not
-    # match the detected version.
-    environ_version = ""
-    if _TF_CUDNN_VERSION in repository_ctx.os.environ:
-        environ_version = repository_ctx.os.environ[_TF_CUDNN_VERSION].strip()
-    if environ_version and not matches_version(environ_version, full_version):
-        cudnn_h_path = repository_ctx.path("%s/include/cudnn.h" %
-                                           cudnn_install_basedir)
-        auto_configure_fail(
-            ("cuDNN version detected from %s (%s) does not match " +
-             "TF_CUDNN_VERSION (%s)") %
-            (str(cudnn_h_path), full_version, environ_version),
-        )
-
-    # We only use the major version since we use the libcudnn libraries that are
-    # only versioned with the major version (e.g. libcudnn.so.5).
-    version = major_version
-    if cpu_value == "Windows":
-        version = "64_" + version
-    return version
-
-def _compute_capabilities(repository_ctx):
-    """Returns a list of strings representing cuda compute capabilities."""
-    if _TF_CUDA_COMPUTE_CAPABILITIES not in repository_ctx.os.environ:
-        return _DEFAULT_CUDA_COMPUTE_CAPABILITIES
-    capabilities_str = repository_ctx.os.environ[_TF_CUDA_COMPUTE_CAPABILITIES]
-    capabilities = capabilities_str.split(",")
-    for capability in capabilities:
-        # Workaround for Skylark's lack of support for regex. This check should
-        # be equivalent to checking:
-        #     if re.match("[0-9]+.[0-9]+", capability) == None:
-        parts = capability.split(".")
-        if len(parts) != 2 or not parts[0].isdigit() or not parts[1].isdigit():
-            auto_configure_fail("Invalid compute capability: %s" % capability)
-    return capabilities
+  cudnn_header_dir = _find_cudnn_header_dir(
+      repository_ctx,
+      cudnn_install_basedir,
+  )
+  major_version = find_cuda_define(
+      repository_ctx,
+      cudnn_header_dir,
+      "cudnn.h",
+      _DEFINE_CUDNN_MAJOR,
+  )
+  minor_version = find_cuda_define(
+      repository_ctx,
+      cudnn_header_dir,
+      "cudnn.h",
+      _DEFINE_CUDNN_MINOR,
+  )
+  patch_version = find_cuda_define(
+      repository_ctx,
+      cudnn_header_dir,
+      "cudnn.h",
+      _DEFINE_CUDNN_PATCHLEVEL,
+  )
+  full_version = "%s.%s.%s" % (major_version, minor_version, patch_version)
+
+  # Check whether TF_CUDNN_VERSION was set by the user and fail if it does not
+  # match the detected version.
+  environ_version = ""
+  if _TF_CUDNN_VERSION in repository_ctx.os.environ:
+    environ_version = repository_ctx.os.environ[_TF_CUDNN_VERSION].strip()
+  if environ_version and not matches_version(environ_version, full_version):
+    cudnn_h_path = repository_ctx.path(
+        "%s/include/cudnn.h" % cudnn_install_basedir)
+    auto_configure_fail(("cuDNN version detected from %s (%s) does not match " +
+                         "TF_CUDNN_VERSION (%s)") %
+                        (str(cudnn_h_path), full_version, environ_version),)
+
+  # We only use the major version since we use the libcudnn libraries that are
+  # only versioned with the major version (e.g. libcudnn.so.5).
+  version = major_version
+  if cpu_value == "Windows":
+    version = "64_" + version
+  return version
+
+
+def compute_capabilities(repository_ctx):
+  """Returns a list of strings representing cuda compute capabilities."""
+  if _TF_CUDA_COMPUTE_CAPABILITIES not in repository_ctx.os.environ:
+    return _DEFAULT_CUDA_COMPUTE_CAPABILITIES
+  capabilities_str = repository_ctx.os.environ[_TF_CUDA_COMPUTE_CAPABILITIES]
+  capabilities = capabilities_str.split(",")
+  for capability in capabilities:
+    # Workaround for Skylark's lack of support for regex. This check should
+    # be equivalent to checking:
+    #     if re.match("[0-9]+.[0-9]+", capability) == None:
+    parts = capability.split(".")
+    if len(parts) != 2 or not parts[0].isdigit() or not parts[1].isdigit():
+      auto_configure_fail("Invalid compute capability: %s" % capability)
+  return capabilities
+
 
 def get_cpu_value(repository_ctx):
-    """Returns the name of the host operating system.
+  """Returns the name of the host operating system.
 
     Args:
       repository_ctx: The repository context.
@@ -648,20 +677,22 @@ def get_cpu_value(repository_ctx):
     Returns:
       A string containing the name of the host operating system.
     """
-    os_name = repository_ctx.os.name.lower()
-    if os_name.startswith("mac os"):
-        return "Darwin"
-    if os_name.find("windows") != -1:
-        return "Windows"
-    result = repository_ctx.execute(["uname", "-s"])
-    return result.stdout.strip()
+  os_name = repository_ctx.os.name.lower()
+  if os_name.startswith("mac os"):
+    return "Darwin"
+  if os_name.find("windows") != -1:
+    return "Windows"
+  result = repository_ctx.execute(["uname", "-s"])
+  return result.stdout.strip()
+
 
 def _is_windows(repository_ctx):
-    """Returns true if the host operating system is windows."""
-    return get_cpu_value(repository_ctx) == "Windows"
+  """Returns true if the host operating system is windows."""
+  return get_cpu_value(repository_ctx) == "Windows"
+
 
 def _lib_name(lib, cpu_value, version = "", static = False):
-    """Constructs the platform-specific name of a library.
+  """Constructs the platform-specific name of a library.
 
     Args:
       lib: The name of the library, such as "cudart"
@@ -672,23 +703,24 @@ def _lib_name(lib, cpu_value, version = "", static = False):
     Returns:
       The platform-specific name of the library.
     """
-    if cpu_value in ("Linux", "FreeBSD"):
-        if static:
-            return "lib%s.a" % lib
-        else:
-            if version:
-                version = ".%s" % version
-            return "lib%s.so%s" % (lib, version)
-    elif cpu_value == "Windows":
-        return "%s.lib" % lib
-    elif cpu_value == "Darwin":
-        if static:
-            return "lib%s.a" % lib
-        elif version:
-            version = ".%s" % version
-        return "lib%s%s.dylib" % (lib, version)
+  if cpu_value in ("Linux", "FreeBSD"):
+    if static:
+      return "lib%s.a" % lib
     else:
-        auto_configure_fail("Invalid cpu_value: %s" % cpu_value)
+      if version:
+        version = ".%s" % version
+      return "lib%s.so%s" % (lib, version)
+  elif cpu_value == "Windows":
+    return "%s.lib" % lib
+  elif cpu_value == "Darwin":
+    if static:
+      return "lib%s.a" % lib
+    elif version:
+      version = ".%s" % version
+    return "lib%s%s.dylib" % (lib, version)
+  else:
+    auto_configure_fail("Invalid cpu_value: %s" % cpu_value)
+
 
 def _find_cuda_lib(
         lib,
@@ -697,7 +729,7 @@ def _find_cuda_lib(
         basedir,
         version = "",
         static = False):
-    """Finds the given CUDA or cuDNN library on the system.
+  """Finds the given CUDA or cuDNN library on the system.
 
     Args:
       lib: The name of the library, such as "cudart"
@@ -712,15 +744,16 @@ def _find_cuda_lib(
         file_name: The basename of the library found on the system.
         path: The full path to the library.
     """
-    file_name = _lib_name(lib, cpu_value, version, static)
-    for relative_path in CUDA_LIB_PATHS:
-        path = repository_ctx.path("%s/%s%s" % (basedir, relative_path, file_name))
-        if path.exists:
-            return struct(file_name = file_name, path = str(path.realpath))
-    auto_configure_fail("Cannot find cuda library %s" % file_name)
+  file_name = _lib_name(lib, cpu_value, version, static)
+  for relative_path in CUDA_LIB_PATHS:
+    path = repository_ctx.path("%s/%s%s" % (basedir, relative_path, file_name))
+    if path.exists:
+      return struct(file_name=file_name, path=str(path.realpath))
+  auto_configure_fail("Cannot find cuda library %s" % file_name)
+
 
 def _find_cupti_header_dir(repository_ctx, cuda_config):
-    """Returns the path to the directory containing cupti.h
+  """Returns the path to the directory containing cupti.h
 
     On most systems, the cupti library is not installed in the same directory as
     the other CUDA libraries but rather in a special extras/CUPTI directory.
@@ -732,14 +765,17 @@ def _find_cupti_header_dir(repository_ctx, cuda_config):
     Returns:
       The path of the directory containing the cupti header.
     """
-    cuda_toolkit_path = cuda_config.cuda_toolkit_path
-    for relative_path in CUPTI_HEADER_PATHS:
-        if repository_ctx.path("%s/%scupti.h" % (cuda_toolkit_path, relative_path)).exists:
-            return ("%s/%s" % (cuda_toolkit_path, relative_path))[:-1]
-    auto_configure_fail("Cannot find cupti.h under %s" % ", ".join([cuda_toolkit_path + "/" + s for s in CUPTI_HEADER_PATHS]))
+  cuda_toolkit_path = cuda_config.cuda_toolkit_path
+  for relative_path in CUPTI_HEADER_PATHS:
+    if repository_ctx.path(
+        "%s/%scupti.h" % (cuda_toolkit_path, relative_path)).exists:
+      return ("%s/%s" % (cuda_toolkit_path, relative_path))[:-1]
+  auto_configure_fail("Cannot find cupti.h under %s" % ", ".join(
+      [cuda_toolkit_path + "/" + s for s in CUPTI_HEADER_PATHS]))
+
 
 def _find_cupti_lib(repository_ctx, cuda_config):
-    """Finds the cupti library on the system.
+  """Finds the cupti library on the system.
 
     On most systems, the cupti library is not installed in the same directory as
     the other CUDA libraries but rather in a special extras/CUPTI directory.
@@ -753,23 +789,23 @@ def _find_cupti_lib(repository_ctx, cuda_config):
         file_name: The basename of the library found on the system.
         path: The full path to the library.
     """
-    file_name = _lib_name(
-        "cupti",
-        cuda_config.cpu_value,
-        cuda_config.cuda_version,
-    )
-    cuda_toolkit_path = cuda_config.cuda_toolkit_path
-    for relative_path in CUPTI_LIB_PATHS:
-        path = repository_ctx.path(
-            "%s/%s%s" % (cuda_toolkit_path, relative_path, file_name),
-        )
-        if path.exists:
-            return struct(file_name = file_name, path = str(path.realpath))
+  file_name = _lib_name(
+      "cupti",
+      cuda_config.cpu_value,
+      cuda_config.cuda_version,
+  )
+  cuda_toolkit_path = cuda_config.cuda_toolkit_path
+  for relative_path in CUPTI_LIB_PATHS:
+    path = repository_ctx.path(
+        "%s/%s%s" % (cuda_toolkit_path, relative_path, file_name),)
+    if path.exists:
+      return struct(file_name=file_name, path=str(path.realpath))
+
+  auto_configure_fail("Cannot find cupti library %s" % file_name)
 
-    auto_configure_fail("Cannot find cupti library %s" % file_name)
 
 def _find_libs(repository_ctx, cuda_config):
-    """Returns the CUDA and cuDNN libraries on the system.
+  """Returns the CUDA and cuDNN libraries on the system.
 
     Args:
       repository_ctx: The repository context.
@@ -778,64 +814,75 @@ def _find_libs(repository_ctx, cuda_config):
     Returns:
       Map of library names to structs of filename and path.
     """
-    cpu_value = cuda_config.cpu_value
-    return {
-        "cuda": _find_cuda_lib("cuda", repository_ctx, cpu_value, cuda_config.cuda_toolkit_path),
-        "cudart": _find_cuda_lib(
-            "cudart",
-            repository_ctx,
-            cpu_value,
-            cuda_config.cuda_toolkit_path,
-            cuda_config.cuda_version,
-        ),
-        "cudart_static": _find_cuda_lib(
-            "cudart_static",
-            repository_ctx,
-            cpu_value,
-            cuda_config.cuda_toolkit_path,
-            cuda_config.cuda_version,
-            static = True,
-        ),
-        "cublas": _find_cuda_lib(
-            "cublas",
-            repository_ctx,
-            cpu_value,
-            cuda_config.cuda_toolkit_path,
-            cuda_config.cuda_version,
-        ),
-        "cusolver": _find_cuda_lib(
-            "cusolver",
-            repository_ctx,
-            cpu_value,
-            cuda_config.cuda_toolkit_path,
-            cuda_config.cuda_version,
-        ),
-        "curand": _find_cuda_lib(
-            "curand",
-            repository_ctx,
-            cpu_value,
-            cuda_config.cuda_toolkit_path,
-            cuda_config.cuda_version,
-        ),
-        "cufft": _find_cuda_lib(
-            "cufft",
-            repository_ctx,
-            cpu_value,
-            cuda_config.cuda_toolkit_path,
-            cuda_config.cuda_version,
-        ),
-        "cudnn": _find_cuda_lib(
-            "cudnn",
-            repository_ctx,
-            cpu_value,
-            cuda_config.cudnn_install_basedir,
-            cuda_config.cudnn_version,
-        ),
-        "cupti": _find_cupti_lib(repository_ctx, cuda_config),
-    }
+  cpu_value = cuda_config.cpu_value
+  return {
+      "cuda":
+          _find_cuda_lib("cuda", repository_ctx, cpu_value,
+                         cuda_config.cuda_toolkit_path),
+      "cudart":
+          _find_cuda_lib(
+              "cudart",
+              repository_ctx,
+              cpu_value,
+              cuda_config.cuda_toolkit_path,
+              cuda_config.cuda_version,
+          ),
+      "cudart_static":
+          _find_cuda_lib(
+              "cudart_static",
+              repository_ctx,
+              cpu_value,
+              cuda_config.cuda_toolkit_path,
+              cuda_config.cuda_version,
+              static=True,
+          ),
+      "cublas":
+          _find_cuda_lib(
+              "cublas",
+              repository_ctx,
+              cpu_value,
+              cuda_config.cuda_toolkit_path,
+              cuda_config.cuda_version,
+          ),
+      "cusolver":
+          _find_cuda_lib(
+              "cusolver",
+              repository_ctx,
+              cpu_value,
+              cuda_config.cuda_toolkit_path,
+              cuda_config.cuda_version,
+          ),
+      "curand":
+          _find_cuda_lib(
+              "curand",
+              repository_ctx,
+              cpu_value,
+              cuda_config.cuda_toolkit_path,
+              cuda_config.cuda_version,
+          ),
+      "cufft":
+          _find_cuda_lib(
+              "cufft",
+              repository_ctx,
+              cpu_value,
+              cuda_config.cuda_toolkit_path,
+              cuda_config.cuda_version,
+          ),
+      "cudnn":
+          _find_cuda_lib(
+              "cudnn",
+              repository_ctx,
+              cpu_value,
+              cuda_config.cudnn_install_basedir,
+              cuda_config.cudnn_version,
+          ),
+      "cupti":
+          _find_cupti_lib(repository_ctx, cuda_config),
+  }
+
 
 def _find_cuda_include_path(repository_ctx, cuda_config):
-    """Returns the path to the directory containing cuda.h
+  """Returns the path to the directory containing cuda.h
 
     Args:
       repository_ctx: The repository context.
@@ -844,14 +891,16 @@ def _find_cuda_include_path(repository_ctx, cuda_config):
     Returns:
       The path of the directory containing the CUDA headers.
     """
-    cuda_toolkit_path = cuda_config.cuda_toolkit_path
-    for relative_path in CUDA_INCLUDE_PATHS:
-        if repository_ctx.path("%s/%scuda.h" % (cuda_toolkit_path, relative_path)).exists:
-            return ("%s/%s" % (cuda_toolkit_path, relative_path))[:-1]
-    auto_configure_fail("Cannot find cuda.h under %s" % cuda_toolkit_path)
+  cuda_toolkit_path = cuda_config.cuda_toolkit_path
+  for relative_path in CUDA_INCLUDE_PATHS:
+    if repository_ctx.path(
+        "%s/%scuda.h" % (cuda_toolkit_path, relative_path)).exists:
+      return ("%s/%s" % (cuda_toolkit_path, relative_path))[:-1]
+  auto_configure_fail("Cannot find cuda.h under %s" % cuda_toolkit_path)
+
 
 def _find_cudnn_header_dir(repository_ctx, cudnn_install_basedir):
-    """Returns the path to the directory containing cudnn.h
+  """Returns the path to the directory containing cudnn.h
 
     Args:
       repository_ctx: The repository context.
@@ -861,15 +910,17 @@ def _find_cudnn_header_dir(repository_ctx, cudnn_install_basedir):
     Returns:
       The path of the directory containing the cudnn header.
     """
-    for relative_path in CUDA_INCLUDE_PATHS:
-        if repository_ctx.path("%s/%scudnn.h" % (cudnn_install_basedir, relative_path)).exists:
-            return ("%s/%s" % (cudnn_install_basedir, relative_path))[:-1]
-    if repository_ctx.path("/usr/include/cudnn.h").exists:
-        return "/usr/include"
-    auto_configure_fail("Cannot find cudnn.h under %s" % cudnn_install_basedir)
+  for relative_path in CUDA_INCLUDE_PATHS:
+    if repository_ctx.path(
+        "%s/%scudnn.h" % (cudnn_install_basedir, relative_path)).exists:
+      return ("%s/%s" % (cudnn_install_basedir, relative_path))[:-1]
+  if repository_ctx.path("/usr/include/cudnn.h").exists:
+    return "/usr/include"
+  auto_configure_fail("Cannot find cudnn.h under %s" % cudnn_install_basedir)
+
 
 def _find_nvvm_libdevice_dir(repository_ctx, cuda_config):
-    """Returns the path to the directory containing libdevice in bitcode format.
+  """Returns the path to the directory containing libdevice in bitcode format.
 
     Args:
       repository_ctx: The repository context.
@@ -878,19 +929,23 @@ def _find_nvvm_libdevice_dir(repository_ctx, cuda_config):
     Returns:
       The path of the directory containing the CUDA headers.
     """
-    cuda_toolkit_path = cuda_config.cuda_toolkit_path
-    for libdevice_file in NVVM_LIBDEVICE_FILES:
-        for relative_path in NVVM_LIBDEVICE_PATHS:
-            if repository_ctx.path("%s/%s%s" % (cuda_toolkit_path, relative_path, libdevice_file)).exists:
-                return ("%s/%s" % (cuda_toolkit_path, relative_path))[:-1]
-    auto_configure_fail("Cannot find libdevice*.bc files under %s" % cuda_toolkit_path)
+  cuda_toolkit_path = cuda_config.cuda_toolkit_path
+  for libdevice_file in NVVM_LIBDEVICE_FILES:
+    for relative_path in NVVM_LIBDEVICE_PATHS:
+      if repository_ctx.path("%s/%s%s" % (cuda_toolkit_path, relative_path,
+                                          libdevice_file)).exists:
+        return ("%s/%s" % (cuda_toolkit_path, relative_path))[:-1]
+  auto_configure_fail(
+      "Cannot find libdevice*.bc files under %s" % cuda_toolkit_path)
+
 
 def _cudart_static_linkopt(cpu_value):
-    """Returns additional platform-specific linkopts for cudart."""
-    return "" if cpu_value == "Darwin" else "\"-lrt\","
+  """Returns additional platform-specific linkopts for cudart."""
+  return "" if cpu_value == "Darwin" else "\"-lrt\","
+
 
 def _get_cuda_config(repository_ctx):
-    """Detects and returns information about the CUDA installation on the system.
+  """Detects and returns information about the CUDA installation on the system.
 
     Args:
       repository_ctx: The repository context.
@@ -904,35 +959,39 @@ def _get_cuda_config(repository_ctx):
         compute_capabilities: A list of the system's CUDA compute capabilities.
         cpu_value: The name of the host operating system.
     """
-    cpu_value = get_cpu_value(repository_ctx)
-    cuda_toolkit_path = _cuda_toolkit_path(repository_ctx)
-    cuda_version = _cuda_version(repository_ctx, cuda_toolkit_path, cpu_value)
-    cudnn_install_basedir = _cudnn_install_basedir(repository_ctx)
-    cudnn_version = _cudnn_version(repository_ctx, cudnn_install_basedir, cpu_value)
-    return struct(
-        cuda_toolkit_path = cuda_toolkit_path,
-        cudnn_install_basedir = cudnn_install_basedir,
-        cuda_version = cuda_version,
-        cudnn_version = cudnn_version,
-        compute_capabilities = _compute_capabilities(repository_ctx),
-        cpu_value = cpu_value,
-    )
+  cpu_value = get_cpu_value(repository_ctx)
+  toolkit_path = cuda_toolkit_path(repository_ctx)
+  cuda_version = _cuda_version(repository_ctx, toolkit_path, cpu_value)
+  cudnn_install_basedir = _cudnn_install_basedir(repository_ctx)
+  cudnn_version = _cudnn_version(repository_ctx, cudnn_install_basedir,
+                                 cpu_value)
+  return struct(
+      cuda_toolkit_path=toolkit_path,
+      cudnn_install_basedir=cudnn_install_basedir,
+      cuda_version=cuda_version,
+      cudnn_version=cudnn_version,
+      compute_capabilities=compute_capabilities(repository_ctx),
+      cpu_value=cpu_value,
+  )
+
 
 def _tpl(repository_ctx, tpl, substitutions = {}, out = None):
-    if not out:
-        out = tpl.replace(":", "/")
-    repository_ctx.template(
-        out,
-        Label("//third_party/gpus/%s.tpl" % tpl),
-        substitutions,
-    )
+  if not out:
+    out = tpl.replace(":", "/")
+  repository_ctx.template(
+      out,
+      Label("//third_party/gpus/%s.tpl" % tpl),
+      substitutions,
+  )
+
 
 def _file(repository_ctx, label):
-    repository_ctx.template(
-        label.replace(":", "/"),
-        Label("//third_party/gpus/%s.tpl" % label),
-        {},
-    )
+  repository_ctx.template(
+      label.replace(":", "/"),
+      Label("//third_party/gpus/%s.tpl" % label),
+      {},
+  )
+
 
 _DUMMY_CROSSTOOL_BZL_FILE = """
 def error_gpu_disabled():
@@ -960,81 +1019,99 @@ error_gpu_disabled()
 """
 
 def _create_dummy_repository(repository_ctx):
-    cpu_value = get_cpu_value(repository_ctx)
+  cpu_value = get_cpu_value(repository_ctx)
+
+  # Set up BUILD file for cuda/.
+  _tpl(
+      repository_ctx,
+      "cuda:build_defs.bzl",
+      {
+          "%{cuda_is_configured}": "False",
+          "%{cuda_extra_copts}": "[]",
+      },
+  )
+  _tpl(
+      repository_ctx,
+      "cuda:BUILD",
+      {
+          "%{cuda_driver_lib}":
+              _lib_name("cuda", cpu_value),
+          "%{cudart_static_lib}":
+              _lib_name(
+                  "cudart_static",
+                  cpu_value,
+                  static=True,
+              ),
+          "%{cudart_static_linkopt}":
+              _cudart_static_linkopt(cpu_value),
+          "%{cudart_lib}":
+              _lib_name("cudart", cpu_value),
+          "%{cublas_lib}":
+              _lib_name("cublas", cpu_value),
+          "%{cusolver_lib}":
+              _lib_name("cusolver", cpu_value),
+          "%{cudnn_lib}":
+              _lib_name("cudnn", cpu_value),
+          "%{cufft_lib}":
+              _lib_name("cufft", cpu_value),
+          "%{curand_lib}":
+              _lib_name("curand", cpu_value),
+          "%{cupti_lib}":
+              _lib_name("cupti", cpu_value),
+          "%{cuda_include_genrules}":
+              "",
+          "%{cuda_headers}":
+              "",
+      },
+  )
 
-    # Set up BUILD file for cuda/.
-    _tpl(
-        repository_ctx,
-        "cuda:build_defs.bzl",
-        {
-            "%{cuda_is_configured}": "False",
-            "%{cuda_extra_copts}": "[]",
-        },
-    )
-    _tpl(
-        repository_ctx,
-        "cuda:BUILD",
-        {
-            "%{cuda_driver_lib}": _lib_name("cuda", cpu_value),
-            "%{cudart_static_lib}": _lib_name(
-                "cudart_static",
-                cpu_value,
-                static = True,
-            ),
-            "%{cudart_static_linkopt}": _cudart_static_linkopt(cpu_value),
-            "%{cudart_lib}": _lib_name("cudart", cpu_value),
-            "%{cublas_lib}": _lib_name("cublas", cpu_value),
-            "%{cusolver_lib}": _lib_name("cusolver", cpu_value),
-            "%{cudnn_lib}": _lib_name("cudnn", cpu_value),
-            "%{cufft_lib}": _lib_name("cufft", cpu_value),
-            "%{curand_lib}": _lib_name("curand", cpu_value),
-            "%{cupti_lib}": _lib_name("cupti", cpu_value),
-            "%{cuda_include_genrules}": "",
-            "%{cuda_headers}": "",
-        },
-    )
+  # Create dummy files for the CUDA toolkit since they are still required by
+  # tensorflow/core/platform/default/build_config:cuda.
+  repository_ctx.file("cuda/cuda/include/cuda.h", "")
+  repository_ctx.file("cuda/cuda/include/cublas.h", "")
+  repository_ctx.file("cuda/cuda/include/cudnn.h", "")
+  repository_ctx.file("cuda/cuda/extras/CUPTI/include/cupti.h", "")
+  repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cuda", cpu_value))
+  repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cudart", cpu_value))
+  repository_ctx.file(
+      "cuda/cuda/lib/%s" % _lib_name("cudart_static", cpu_value))
+  repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cublas", cpu_value))
+  repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cusolver", cpu_value))
+  repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cudnn", cpu_value))
+  repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("curand", cpu_value))
+  repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cufft", cpu_value))
+  repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cupti", cpu_value))
+
+  # Set up cuda_config.h, which is used by
+  # tensorflow/stream_executor/dso_loader.cc.
+  _tpl(
+      repository_ctx,
+      "cuda:cuda_config.h",
+      {
+          "%{cuda_version}":
+              _DEFAULT_CUDA_VERSION,
+          "%{cudnn_version}":
+              _DEFAULT_CUDNN_VERSION,
+          "%{cuda_compute_capabilities}":
+              ",".join([
+                  "CudaVersion(\"%s\")" % c
+                  for c in _DEFAULT_CUDA_COMPUTE_CAPABILITIES
+              ]),
+          "%{cuda_toolkit_path}":
+              _DEFAULT_CUDA_TOOLKIT_PATH,
+      },
+      "cuda/cuda/cuda_config.h",
+  )
 
-    # Create dummy files for the CUDA toolkit since they are still required by
-    # tensorflow/core/platform/default/build_config:cuda.
-    repository_ctx.file("cuda/cuda/include/cuda.h", "")
-    repository_ctx.file("cuda/cuda/include/cublas.h", "")
-    repository_ctx.file("cuda/cuda/include/cudnn.h", "")
-    repository_ctx.file("cuda/cuda/extras/CUPTI/include/cupti.h", "")
-    repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cuda", cpu_value))
-    repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cudart", cpu_value))
-    repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cudart_static", cpu_value))
-    repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cublas", cpu_value))
-    repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cusolver", cpu_value))
-    repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cudnn", cpu_value))
-    repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("curand", cpu_value))
-    repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cufft", cpu_value))
-    repository_ctx.file("cuda/cuda/lib/%s" % _lib_name("cupti", cpu_value))
-
-    # Set up cuda_config.h, which is used by
-    # tensorflow/stream_executor/dso_loader.cc.
-    _tpl(
-        repository_ctx,
-        "cuda:cuda_config.h",
-        {
-            "%{cuda_version}": _DEFAULT_CUDA_VERSION,
-            "%{cudnn_version}": _DEFAULT_CUDNN_VERSION,
-            "%{cuda_compute_capabilities}": ",".join([
-                "CudaVersion(\"%s\")" % c
-                for c in _DEFAULT_CUDA_COMPUTE_CAPABILITIES
-            ]),
-            "%{cuda_toolkit_path}": _DEFAULT_CUDA_TOOLKIT_PATH,
-        },
-        "cuda/cuda/cuda_config.h",
-    )
+  # If cuda_configure is not configured to build with GPU support, and the user
+  # attempts to build with --config=cuda, add a dummy build rule to intercept
+  # this and fail with an actionable error message.
+  repository_ctx.file(
+      "crosstool/error_gpu_disabled.bzl",
+      _DUMMY_CROSSTOOL_BZL_FILE,
+  )
+  repository_ctx.file("crosstool/BUILD", _DUMMY_CROSSTOOL_BUILD_FILE)
 
-    # If cuda_configure is not configured to build with GPU support, and the user
-    # attempts to build with --config=cuda, add a dummy build rule to intercept
-    # this and fail with an actionable error message.
-    repository_ctx.file(
-        "crosstool/error_gpu_disabled.bzl",
-        _DUMMY_CROSSTOOL_BZL_FILE,
-    )
-    repository_ctx.file("crosstool/BUILD", _DUMMY_CROSSTOOL_BUILD_FILE)
 
 def _execute(
         repository_ctx,
@@ -1042,35 +1119,35 @@ def _execute(
         error_msg = None,
         error_details = None,
         empty_stdout_fine = False):
-    """Executes an arbitrary shell command.
+  """Executes an arbitrary shell command.
 
     Args:
       repository_ctx: the repository_ctx object
       cmdline: list of strings, the command to execute
       error_msg: string, a summary of the error if the command fails
       error_details: string, details about the error or steps to fix it
-      empty_stdout_fine: bool, if True, an empty stdout result is fine, otherwise
-        it's an error
-    Return:
-      the result of repository_ctx.execute(cmdline)
-    """
-    result = repository_ctx.execute(cmdline)
-    if result.stderr or not (empty_stdout_fine or result.stdout):
-        auto_configure_fail(
-            "\n".join([
-                error_msg.strip() if error_msg else "Repository command failed",
-                result.stderr.strip(),
-                error_details if error_details else "",
-            ]),
-        )
-    return result
+      empty_stdout_fine: bool, if True, an empty stdout result is fine,
+        otherwise it's an error
+    Return: the result of repository_ctx.execute(cmdline)
+  """
+  result = repository_ctx.execute(cmdline)
+  if result.stderr or not (empty_stdout_fine or result.stdout):
+    auto_configure_fail(
+        "\n".join([
+            error_msg.strip() if error_msg else "Repository command failed",
+            result.stderr.strip(),
+            error_details if error_details else "",
+        ]),)
+  return result
+
 
 def _norm_path(path):
-    """Returns a path with '/' and remove the trailing slash."""
-    path = path.replace("\\", "/")
-    if path[-1] == "/":
-        path = path[:-1]
-    return path
+  """Returns a path with '/' and remove the trailing slash."""
+  path = path.replace("\\", "/")
+  if path[-1] == "/":
+    path = path[:-1]
+  return path
+
 
 def symlink_genrule_for_dir(
         repository_ctx,
@@ -1079,167 +1156,174 @@ def symlink_genrule_for_dir(
         genrule_name,
         src_files = [],
         dest_files = []):
-    """Returns a genrule to symlink(or copy if on Windows) a set of files.
+  """Returns a genrule to symlink(or copy if on Windows) a set of files.
 
     If src_dir is passed, files will be read from the given directory; otherwise
     we assume files are in src_files and dest_files
     """
-    if src_dir != None:
-        src_dir = _norm_path(src_dir)
-        dest_dir = _norm_path(dest_dir)
-        files = "\n".join(sorted(_read_dir(repository_ctx, src_dir).splitlines()))
-
-        # Create a list with the src_dir stripped to use for outputs.
-        dest_files = files.replace(src_dir, "").splitlines()
-        src_files = files.splitlines()
-    command = []
-    if not _is_windows(repository_ctx):
-        # We clear folders that might have been generated previously to avoid
-        # undesired inclusions
-        command.append('if [ -d "$(@D)/extras" ]; then rm $(@D)/extras -drf; fi')
-        command.append('if [ -d "$(@D)/include" ]; then rm $(@D)/include -drf; fi')
-        command.append('if [ -d "$(@D)/lib" ]; then rm $(@D)/lib -drf; fi')
-        command.append('if [ -d "$(@D)/nvvm" ]; then rm $(@D)/nvvm -drf; fi')
-    outs = []
-    for i in range(len(dest_files)):
-        if dest_files[i] != "":
-            # If we have only one file to link we do not want to use the dest_dir, as
-            # $(@D) will include the full path to the file.
-            dest = "$(@D)/" + dest_dir + dest_files[i] if len(dest_files) != 1 else "$(@D)/" + dest_files[i]
-
-            # Copy the headers to create a sandboxable setup.
-            cmd = "cp -f"
-            command.append(cmd + ' "%s" "%s"' % (src_files[i], dest))
-            outs.append('        "' + dest_dir + dest_files[i] + '",')
-    genrule = _genrule(
-        src_dir,
-        genrule_name,
-        " && ".join(command),
-        "\n".join(outs),
-    )
-    return genrule
+  if src_dir != None:
+    src_dir = _norm_path(src_dir)
+    dest_dir = _norm_path(dest_dir)
+    files = "\n".join(sorted(_read_dir(repository_ctx, src_dir).splitlines()))
+
+    # Create a list with the src_dir stripped to use for outputs.
+    dest_files = files.replace(src_dir, "").splitlines()
+    src_files = files.splitlines()
+  command = []
+  if not _is_windows(repository_ctx):
+    # We clear folders that might have been generated previously to avoid
+    # undesired inclusions
+    command.append('if [ -d "$(@D)/extras" ]; then rm $(@D)/extras -drf; fi')
+    command.append('if [ -d "$(@D)/include" ]; then rm $(@D)/include -drf; fi')
+    command.append('if [ -d "$(@D)/lib" ]; then rm $(@D)/lib -drf; fi')
+    command.append('if [ -d "$(@D)/nvvm" ]; then rm $(@D)/nvvm -drf; fi')
+  outs = []
+  for i in range(len(dest_files)):
+    if dest_files[i] != "":
+      # If we have only one file to link we do not want to use the dest_dir, as
+      # $(@D) will include the full path to the file.
+      dest = "$(@D)/" + dest_dir + dest_files[i] if len(
+          dest_files) != 1 else "$(@D)/" + dest_files[i]
+
+      # Copy the headers to create a sandboxable setup.
+      cmd = "cp -f"
+      command.append(cmd + ' "%s" "%s"' % (src_files[i], dest))
+      outs.append('        "' + dest_dir + dest_files[i] + '",')
+  genrule = _genrule(
+      src_dir,
+      genrule_name,
+      " && ".join(command),
+      "\n".join(outs),
+  )
+  return genrule
+
 
 def _genrule(src_dir, genrule_name, command, outs):
-    """Returns a string with a genrule.
+  """Returns a string with a genrule.
 
     Genrule executes the given command and produces the given outputs.
     """
-    return (
-        "genrule(\n" +
-        '    name = "' +
-        genrule_name + '",\n' +
-        "    outs = [\n" +
-        outs +
-        "\n    ],\n" +
-        '    cmd = """\n' +
-        command +
-        '\n   """,\n' +
-        ")\n"
-    )
+  return (
+      "genrule(\n" + '    name = "' + genrule_name + '",\n' + "    outs = [\n" +
+      outs + "\n    ],\n" + '    cmd = """\n' + command + '\n   """,\n' + ")\n")
+
 
 def _read_dir(repository_ctx, src_dir):
-    """Returns a string with all files in a directory.
+  """Returns a string with all files in a directory.
 
     Finds all files inside a directory, traversing subfolders and following
     symlinks. The returned string contains the full path of all files
     separated by line breaks.
     """
-    if _is_windows(repository_ctx):
-        src_dir = src_dir.replace("/", "\\")
-        find_result = _execute(
-            repository_ctx,
-            ["cmd.exe", "/c", "dir", src_dir, "/b", "/s", "/a-d"],
-            empty_stdout_fine = True,
-        )
+  if _is_windows(repository_ctx):
+    src_dir = src_dir.replace("/", "\\")
+    find_result = _execute(
+        repository_ctx,
+        ["cmd.exe", "/c", "dir", src_dir, "/b", "/s", "/a-d"],
+        empty_stdout_fine=True,
+    )
+
+    # src_files will be used in genrule.outs where the paths must
+    # use forward slashes.
+    result = find_result.stdout.replace("\\", "/")
+  else:
+    find_result = _execute(
+        repository_ctx,
+        ["find", src_dir, "-follow", "-type", "f"],
+        empty_stdout_fine=True,
+    )
+    result = find_result.stdout
+  return result
 
-        # src_files will be used in genrule.outs where the paths must
-        # use forward slashes.
-        result = find_result.stdout.replace("\\", "/")
-    else:
-        find_result = _execute(
-            repository_ctx,
-            ["find", src_dir, "-follow", "-type", "f"],
-            empty_stdout_fine = True,
-        )
-        result = find_result.stdout
-    return result
 
 def _flag_enabled(repository_ctx, flag_name):
-    if flag_name in repository_ctx.os.environ:
-        value = repository_ctx.os.environ[flag_name].strip()
-        return value == "1"
-    return False
+  if flag_name in repository_ctx.os.environ:
+    value = repository_ctx.os.environ[flag_name].strip()
+    return value == "1"
+  return False
+
 
 def _use_cuda_clang(repository_ctx):
-    return _flag_enabled(repository_ctx, "TF_CUDA_CLANG")
+  return _flag_enabled(repository_ctx, "TF_CUDA_CLANG")
+
 
 def _compute_cuda_extra_copts(repository_ctx, compute_capabilities):
-    if _use_cuda_clang(repository_ctx):
-        capability_flags = ["--cuda-gpu-arch=sm_" +
-                            cap.replace(".", "") for cap in compute_capabilities]
-    else:
-        # Capabilities are handled in the "crosstool_wrapper_driver_is_not_gcc" for nvcc
-        capability_flags = []
-    return str(capability_flags)
+  if _use_cuda_clang(repository_ctx):
+    capability_flags = [
+        "--cuda-gpu-arch=sm_" + cap.replace(".", "")
+        for cap in compute_capabilities
+    ]
+  else:
+    # Capabilities are handled in the "crosstool_wrapper_driver_is_not_gcc" for nvcc
+    # TODO(csigg): Make this consistent with cuda clang and pass to crosstool.
+    capability_flags = []
+  return str(capability_flags)
+
 
 def _create_local_cuda_repository(repository_ctx):
-    """Creates the repository containing files set up to build with CUDA."""
-    cuda_config = _get_cuda_config(repository_ctx)
+  """Creates the repository containing files set up to build with CUDA."""
+  cuda_config = _get_cuda_config(repository_ctx)
 
-    cuda_include_path = _find_cuda_include_path(repository_ctx, cuda_config)
-    cudnn_header_dir = _find_cudnn_header_dir(
-        repository_ctx,
-        cuda_config.cudnn_install_basedir,
-    )
-    cupti_header_dir = _find_cupti_header_dir(repository_ctx, cuda_config)
-    nvvm_libdevice_dir = _find_nvvm_libdevice_dir(repository_ctx, cuda_config)
-
-    # Set up symbolic links for the cuda toolkit by creating genrules to do
-    # symlinking. We create one genrule for each directory we want to track under
-    # cuda_toolkit_path
-    cuda_toolkit_path = cuda_config.cuda_toolkit_path
-    genrules = [symlink_genrule_for_dir(
-        repository_ctx,
-        cuda_include_path,
-        "cuda/include",
-        "cuda-include",
-    )]
-    genrules.append(symlink_genrule_for_dir(
-        repository_ctx,
-        nvvm_libdevice_dir,
-        "cuda/nvvm/libdevice",
-        "cuda-nvvm",
-    ))
-    genrules.append(symlink_genrule_for_dir(
-        repository_ctx,
-        cupti_header_dir,
-        "cuda/extras/CUPTI/include",
-        "cuda-extras",
-    ))
-
-    cuda_libs = _find_libs(repository_ctx, cuda_config)
-    cuda_lib_src = []
-    cuda_lib_dest = []
-    for lib in cuda_libs.values():
-        cuda_lib_src.append(lib.path)
-        cuda_lib_dest.append("cuda/lib/" + lib.file_name)
-    genrules.append(symlink_genrule_for_dir(
-        repository_ctx,
-        None,
-        "",
-        "cuda-lib",
-        cuda_lib_src,
-        cuda_lib_dest,
-    ))
-
-    # Set up the symbolic links for cudnn if cndnn was not installed to
-    # CUDA_TOOLKIT_PATH.
-    included_files = _read_dir(repository_ctx, cuda_include_path).replace(
-        cuda_include_path,
-        "",
-    ).splitlines()
-    if "/cudnn.h" not in included_files:
-        genrules.append(symlink_genrule_for_dir(
+  cuda_include_path = _find_cuda_include_path(repository_ctx, cuda_config)
+  cudnn_header_dir = _find_cudnn_header_dir(
+      repository_ctx,
+      cuda_config.cudnn_install_basedir,
+  )
+  cupti_header_dir = _find_cupti_header_dir(repository_ctx, cuda_config)
+  nvvm_libdevice_dir = _find_nvvm_libdevice_dir(repository_ctx, cuda_config)
+
+  # Set up symbolic links for the cuda toolkit by creating genrules to do
+  # symlinking. We create one genrule for each directory we want to track under
+  # cuda_toolkit_path
+  cuda_toolkit_path = cuda_config.cuda_toolkit_path
+  genrules = [
+      symlink_genrule_for_dir(
+          repository_ctx,
+          cuda_include_path,
+          "cuda/include",
+          "cuda-include",
+      )
+  ]
+  genrules.append(
+      symlink_genrule_for_dir(
+          repository_ctx,
+          nvvm_libdevice_dir,
+          "cuda/nvvm/libdevice",
+          "cuda-nvvm",
+      ))
+  genrules.append(
+      symlink_genrule_for_dir(
+          repository_ctx,
+          cupti_header_dir,
+          "cuda/extras/CUPTI/include",
+          "cuda-extras",
+      ))
+
+  cuda_libs = _find_libs(repository_ctx, cuda_config)
+  cuda_lib_src = []
+  cuda_lib_dest = []
+  for lib in cuda_libs.values():
+    cuda_lib_src.append(lib.path)
+    cuda_lib_dest.append("cuda/lib/" + lib.file_name)
+  genrules.append(
+      symlink_genrule_for_dir(
+          repository_ctx,
+          None,
+          "",
+          "cuda-lib",
+          cuda_lib_src,
+          cuda_lib_dest,
+      ))
+
+  # Set up the symbolic links for cudnn if cndnn was not installed to
+  # CUDA_TOOLKIT_PATH.
+  included_files = _read_dir(repository_ctx, cuda_include_path).replace(
+      cuda_include_path,
+      "",
+  ).splitlines()
+  if "/cudnn.h" not in included_files:
+    genrules.append(
+        symlink_genrule_for_dir(
             repository_ctx,
             None,
             "cuda/include/",
@@ -1247,204 +1331,229 @@ def _create_local_cuda_repository(repository_ctx):
             [cudnn_header_dir + "/cudnn.h"],
             ["cudnn.h"],
         ))
-    else:
-        genrules.append(
-            "filegroup(\n" +
-            '    name = "cudnn-include",\n' +
-            "    srcs = [],\n" +
-            ")\n",
-        )
-
-    # Set up BUILD file for cuda/
-    _tpl(
-        repository_ctx,
-        "cuda:build_defs.bzl",
-        {
-            "%{cuda_is_configured}": "True",
-            "%{cuda_extra_copts}": _compute_cuda_extra_copts(
-                repository_ctx,
-                cuda_config.compute_capabilities,
-            ),
-        },
-    )
-    _tpl(
-        repository_ctx,
-        "cuda:BUILD.windows" if _is_windows(repository_ctx) else "cuda:BUILD",
-        {
-            "%{cuda_driver_lib}": cuda_libs["cuda"].file_name,
-            "%{cudart_static_lib}": cuda_libs["cudart_static"].file_name,
-            "%{cudart_static_linkopt}": _cudart_static_linkopt(
-                cuda_config.cpu_value,
-            ),
-            "%{cudart_lib}": cuda_libs["cudart"].file_name,
-            "%{cublas_lib}": cuda_libs["cublas"].file_name,
-            "%{cusolver_lib}": cuda_libs["cusolver"].file_name,
-            "%{cudnn_lib}": cuda_libs["cudnn"].file_name,
-            "%{cufft_lib}": cuda_libs["cufft"].file_name,
-            "%{curand_lib}": cuda_libs["curand"].file_name,
-            "%{cupti_lib}": cuda_libs["cupti"].file_name,
-            "%{cuda_include_genrules}": "\n".join(genrules),
-            "%{cuda_headers}": ('":cuda-include",\n' +
-                                '        ":cudnn-include",'),
-        },
-        "cuda/BUILD",
-    )
-
-    is_cuda_clang = _use_cuda_clang(repository_ctx)
+  else:
+    genrules.append(
+        "filegroup(\n" + '    name = "cudnn-include",\n' + "    srcs = [],\n" +
+        ")\n",)
+
+  # Set up BUILD file for cuda/
+  _tpl(
+      repository_ctx,
+      "cuda:build_defs.bzl",
+      {
+          "%{cuda_is_configured}":
+              "True",
+          "%{cuda_extra_copts}":
+              _compute_cuda_extra_copts(
+                  repository_ctx,
+                  cuda_config.compute_capabilities,
+              ),
+      },
+  )
+  _tpl(
+      repository_ctx,
+      "cuda:BUILD.windows" if _is_windows(repository_ctx) else "cuda:BUILD",
+      {
+          "%{cuda_driver_lib}":
+              cuda_libs["cuda"].file_name,
+          "%{cudart_static_lib}":
+              cuda_libs["cudart_static"].file_name,
+          "%{cudart_static_linkopt}":
+              _cudart_static_linkopt(cuda_config.cpu_value,),
+          "%{cudart_lib}":
+              cuda_libs["cudart"].file_name,
+          "%{cublas_lib}":
+              cuda_libs["cublas"].file_name,
+          "%{cusolver_lib}":
+              cuda_libs["cusolver"].file_name,
+          "%{cudnn_lib}":
+              cuda_libs["cudnn"].file_name,
+          "%{cufft_lib}":
+              cuda_libs["cufft"].file_name,
+          "%{curand_lib}":
+              cuda_libs["curand"].file_name,
+          "%{cupti_lib}":
+              cuda_libs["cupti"].file_name,
+          "%{cuda_include_genrules}":
+              "\n".join(genrules),
+          "%{cuda_headers}": ('":cuda-include",\n' + '        ":cudnn-include",'
+                             ),
+      },
+      "cuda/BUILD",
+  )
 
-    should_download_clang = is_cuda_clang and _flag_enabled(
-        repository_ctx,
-        _TF_DOWNLOAD_CLANG,
-    )
-    if should_download_clang:
-        download_clang(repository_ctx, "crosstool/extra_tools")
-
-    # Set up crosstool/
-    cc = find_cc(repository_ctx)
-    cc_fullpath = cc if not should_download_clang else "crosstool/" + cc
-
-    host_compiler_includes = _host_compiler_includes(repository_ctx, cc_fullpath)
-    cuda_defines = {}
-    # Bazel sets '-B/usr/bin' flag to workaround build errors on RHEL (see
-    # https://github.com/bazelbuild/bazel/issues/760).
-    # However, this stops our custom clang toolchain from picking the provided
-    # LLD linker, so we're only adding '-B/usr/bin' when using non-downloaded
-    # toolchain.
-    # TODO: when bazel stops adding '-B/usr/bin' by default, remove this
-    #       flag from the CROSSTOOL completely (see
-    #       https://github.com/bazelbuild/bazel/issues/5634)
-    if should_download_clang:
-      cuda_defines["%{linker_bin_path_flag}"] = ""
-    else:
-      cuda_defines["%{linker_bin_path_flag}"] = 'flag: "-B/usr/bin"'
+  is_cuda_clang = _use_cuda_clang(repository_ctx)
 
-    if is_cuda_clang:
-        cuda_defines["%{host_compiler_path}"] = str(cc)
-        cuda_defines["%{host_compiler_warnings}"] = """
+  should_download_clang = is_cuda_clang and _flag_enabled(
+      repository_ctx,
+      _TF_DOWNLOAD_CLANG,
+  )
+  if should_download_clang:
+    download_clang(repository_ctx, "crosstool/extra_tools")
+
+  # Set up crosstool/
+  cc = find_cc(repository_ctx)
+  cc_fullpath = cc if not should_download_clang else "crosstool/" + cc
+
+  host_compiler_includes = _host_compiler_includes(repository_ctx, cc_fullpath)
+  cuda_defines = {}
+  # Bazel sets '-B/usr/bin' flag to workaround build errors on RHEL (see
+  # https://github.com/bazelbuild/bazel/issues/760).
+  # However, this stops our custom clang toolchain from picking the provided
+  # LLD linker, so we're only adding '-B/usr/bin' when using non-downloaded
+  # toolchain.
+  # TODO: when bazel stops adding '-B/usr/bin' by default, remove this
+  #       flag from the CROSSTOOL completely (see
+  #       https://github.com/bazelbuild/bazel/issues/5634)
+  if should_download_clang:
+    cuda_defines["%{linker_bin_path_flag}"] = ""
+  else:
+    cuda_defines["%{linker_bin_path_flag}"] = 'flag: "-B/usr/bin"'
+
+  if is_cuda_clang:
+    cuda_defines["%{host_compiler_path}"] = str(cc)
+    cuda_defines["%{host_compiler_warnings}"] = """
         # Some parts of the codebase set -Werror and hit this warning, so
         # switch it off for now.
         flag: "-Wno-invalid-partial-specialization"
     """
-        cuda_defines["%{host_compiler_includes}"] = host_compiler_includes
-        _tpl(repository_ctx, "crosstool:BUILD", {"%{linker_files}": ":empty", "%{win_linker_files}": ":empty"})
-        repository_ctx.file("crosstool/clang/bin/crosstool_wrapper_driver_is_not_gcc", "")
-        repository_ctx.file("crosstool/windows/msvc_wrapper_for_nvcc.py", "")
-        repository_ctx.file("crosstool/windows/msvc_wrapper_for_nvcc.bat", "")
-    else:
-        cuda_defines["%{host_compiler_path}"] = "clang/bin/crosstool_wrapper_driver_is_not_gcc"
-        cuda_defines["%{host_compiler_warnings}"] = ""
-
-        # nvcc has the system include paths built in and will automatically
-        # search them; we cannot work around that, so we add the relevant cuda
-        # system paths to the allowed compiler specific include paths.
-        cuda_defines["%{host_compiler_includes}"] = (
-            host_compiler_includes + "\n" +
-            _cuda_include_path(repository_ctx, cuda_config) +
-            "\n  cxx_builtin_include_directory: \"%s\"" % cupti_header_dir +
-            "\n  cxx_builtin_include_directory: \"%s\"" % cudnn_header_dir)
-        nvcc_path = str(repository_ctx.path("%s/bin/nvcc%s" %
-                                            (
-                                                cuda_config.cuda_toolkit_path,
-                                                ".exe" if _is_windows(repository_ctx) else "",
-                                            )))
-        _tpl(
-            repository_ctx,
-            "crosstool:BUILD",
-            {
-                "%{linker_files}": ":crosstool_wrapper_driver_is_not_gcc",
-                "%{win_linker_files}": ":windows_msvc_wrapper_files",
-            },
-        )
-        wrapper_defines = {
-            "%{cpu_compiler}": str(cc),
-            "%{cuda_version}": cuda_config.cuda_version,
-            "%{nvcc_path}": nvcc_path,
-            "%{gcc_host_compiler_path}": str(cc),
-            "%{cuda_compute_capabilities}": ", ".join(
-                ["\"%s\"" % c for c in cuda_config.compute_capabilities],
-            ),
-            "%{nvcc_tmp_dir}": _get_nvcc_tmp_dir_for_windows(repository_ctx),
-        }
-        _tpl(
-            repository_ctx,
-            "crosstool:clang/bin/crosstool_wrapper_driver_is_not_gcc",
-            wrapper_defines,
-        )
-        _tpl(
-            repository_ctx,
-            "crosstool:windows/msvc_wrapper_for_nvcc.py",
-            wrapper_defines,
-        )
-        _tpl(
-            repository_ctx,
-            "crosstool:windows/msvc_wrapper_for_nvcc.bat",
-            {
-                "%{python_binary}": _get_python_bin(repository_ctx),
-            },
-        )
-
+    cuda_defines["%{host_compiler_includes}"] = host_compiler_includes
+    _tpl(repository_ctx, "crosstool:BUILD", {
+        "%{linker_files}": ":empty",
+        "%{win_linker_files}": ":empty"
+    })
+    repository_ctx.file(
+        "crosstool/clang/bin/crosstool_wrapper_driver_is_not_gcc", "")
+    repository_ctx.file("crosstool/windows/msvc_wrapper_for_nvcc.py", "")
+    repository_ctx.file("crosstool/windows/msvc_wrapper_for_nvcc.bat", "")
+  else:
+    cuda_defines[
+        "%{host_compiler_path}"] = "clang/bin/crosstool_wrapper_driver_is_not_gcc"
+    cuda_defines["%{host_compiler_warnings}"] = ""
+
+    # nvcc has the system include paths built in and will automatically
+    # search them; we cannot work around that, so we add the relevant cuda
+    # system paths to the allowed compiler specific include paths.
+    cuda_defines["%{host_compiler_includes}"] = (
+        host_compiler_includes + "\n" + _cuda_include_path(
+            repository_ctx, cuda_config) +
+        "\n  cxx_builtin_include_directory: \"%s\"" % cupti_header_dir +
+        "\n  cxx_builtin_include_directory: \"%s\"" % cudnn_header_dir)
+    nvcc_path = str(
+        repository_ctx.path("%s/bin/nvcc%s" % (
+            cuda_config.cuda_toolkit_path,
+            ".exe" if _is_windows(repository_ctx) else "",
+        )))
     _tpl(
         repository_ctx,
-        "crosstool:CROSSTOOL",
-        cuda_defines + _get_win_cuda_defines(repository_ctx),
-        out = "crosstool/CROSSTOOL",
+        "crosstool:BUILD",
+        {
+            "%{linker_files}": ":crosstool_wrapper_driver_is_not_gcc",
+            "%{win_linker_files}": ":windows_msvc_wrapper_files",
+        },
     )
-
-    # Set up cuda_config.h, which is used by
-    # tensorflow/stream_executor/dso_loader.cc.
+    wrapper_defines = {
+        "%{cpu_compiler}":
+            str(cc),
+        "%{cuda_version}":
+            cuda_config.cuda_version,
+        "%{nvcc_path}":
+            nvcc_path,
+        "%{gcc_host_compiler_path}":
+            str(cc),
+        "%{cuda_compute_capabilities}":
+            ", ".join(
+                ["\"%s\"" % c for c in cuda_config.compute_capabilities],),
+        "%{nvcc_tmp_dir}":
+            _get_nvcc_tmp_dir_for_windows(repository_ctx),
+    }
     _tpl(
         repository_ctx,
-        "cuda:cuda_config.h",
-        {
-            "%{cuda_version}": cuda_config.cuda_version,
-            "%{cudnn_version}": cuda_config.cudnn_version,
-            "%{cuda_compute_capabilities}": ",".join(
-                [
-                    "CudaVersion(\"%s\")" % c
-                    for c in cuda_config.compute_capabilities
-                ],
-            ),
-            "%{cuda_toolkit_path}": cuda_config.cuda_toolkit_path,
-        },
-        "cuda/cuda/cuda_config.h",
+        "crosstool:clang/bin/crosstool_wrapper_driver_is_not_gcc",
+        wrapper_defines,
     )
-
-def _create_remote_cuda_repository(repository_ctx, remote_config_repo):
-    """Creates pointers to a remotely configured repo set up to build with CUDA."""
     _tpl(
         repository_ctx,
-        "cuda:build_defs.bzl",
-        {
-            "%{cuda_is_configured}": "True",
-            "%{cuda_extra_copts}": _compute_cuda_extra_copts(
-                repository_ctx,
-                _compute_capabilities(repository_ctx),
-            ),
-        },
+        "crosstool:windows/msvc_wrapper_for_nvcc.py",
+        wrapper_defines,
     )
     _tpl(
         repository_ctx,
-        "cuda:remote.BUILD",
+        "crosstool:windows/msvc_wrapper_for_nvcc.bat",
         {
-            "%{remote_cuda_repo}": remote_config_repo,
+            "%{python_binary}": _get_python_bin(repository_ctx),
         },
-        "cuda/BUILD",
     )
-    _tpl(repository_ctx, "crosstool:remote.BUILD", {
-        "%{remote_cuda_repo}": remote_config_repo,
-    }, "crosstool/BUILD")
+
+  _tpl(
+      repository_ctx,
+      "crosstool:CROSSTOOL",
+      cuda_defines + _get_win_cuda_defines(repository_ctx),
+      out="crosstool/CROSSTOOL",
+  )
+
+  # Set up cuda_config.h, which is used by
+  # tensorflow/stream_executor/dso_loader.cc.
+  _tpl(
+      repository_ctx,
+      "cuda:cuda_config.h",
+      {
+          "%{cuda_version}":
+              cuda_config.cuda_version,
+          "%{cudnn_version}":
+              cuda_config.cudnn_version,
+          "%{cuda_compute_capabilities}":
+              ",".join([
+                  "CudaVersion(\"%s\")" % c
+                  for c in cuda_config.compute_capabilities
+              ],),
+          "%{cuda_toolkit_path}":
+              cuda_config.cuda_toolkit_path,
+      },
+      "cuda/cuda/cuda_config.h",
+  )
+
+
+def _create_remote_cuda_repository(repository_ctx, remote_config_repo):
+  """Creates pointers to a remotely configured repo set up to build with CUDA."""
+  _tpl(
+      repository_ctx,
+      "cuda:build_defs.bzl",
+      {
+          "%{cuda_is_configured}":
+              "True",
+          "%{cuda_extra_copts}":
+              _compute_cuda_extra_copts(
+                  repository_ctx,
+                  compute_capabilities(repository_ctx),
+              ),
+      },
+  )
+  _tpl(
+      repository_ctx,
+      "cuda:remote.BUILD",
+      {
+          "%{remote_cuda_repo}": remote_config_repo,
+      },
+      "cuda/BUILD",
+  )
+  _tpl(repository_ctx, "crosstool:remote.BUILD", {
+      "%{remote_cuda_repo}": remote_config_repo,
+  }, "crosstool/BUILD")
+
 
 def _cuda_autoconf_impl(repository_ctx):
-    """Implementation of the cuda_autoconf repository rule."""
-    if not _enable_cuda(repository_ctx):
-        _create_dummy_repository(repository_ctx)
-    elif _TF_CUDA_CONFIG_REPO in repository_ctx.os.environ:
-        _create_remote_cuda_repository(
-            repository_ctx,
-            repository_ctx.os.environ[_TF_CUDA_CONFIG_REPO],
-        )
-    else:
-        _create_local_cuda_repository(repository_ctx)
+  """Implementation of the cuda_autoconf repository rule."""
+  if not _enable_cuda(repository_ctx):
+    _create_dummy_repository(repository_ctx)
+  elif _TF_CUDA_CONFIG_REPO in repository_ctx.os.environ:
+    _create_remote_cuda_repository(
+        repository_ctx,
+        repository_ctx.os.environ[_TF_CUDA_CONFIG_REPO],
+    )
+  else:
+    _create_local_cuda_repository(repository_ctx)
+
 
 cuda_configure = repository_rule(
     implementation = _cuda_autoconf_impl,