1#!/usr/bin/env python3 2# Copyright 2018 The Chromium Authors 3# Use of this source code is governed by a BSD-style license that can be 4# found in the LICENSE file. 5"""Removes code coverage flags from invocations of the Clang C/C++ compiler. 6 7If the GN arg `use_clang_coverage=true`, this script will be invoked by default. 8GN will add coverage instrumentation flags to almost all source files. 9 10This script is used to remove instrumentation flags from a subset of the source 11files. By default, it will not remove flags from any files. If the option 12--files-to-instrument is passed, this script will remove flags from all files 13except the ones listed in --files-to-instrument. 14 15This script also contains hard-coded exclusion lists of files to never 16instrument, indexed by target operating system. Files in these lists have their 17flags removed in both modes. The OS can be selected with --target-os. 18 19This script also contains hard-coded force lists of files to always instrument, 20indexed by target operating system. Files in these lists never have their flags 21removed in either mode. The OS can be selected with --target-os. 22 23The order of precedence is: force list, exclusion list, --files-to-instrument. 24 25The path to the coverage instrumentation input file should be relative to the 26root build directory, and the file consists of multiple lines where each line 27represents a path to a source file, and the specified paths must be relative to 28the root build directory. e.g. ../../base/task/post_task.cc for build 29directory 'out/Release'. The paths should be written using OS-native path 30separators for the current platform. 31 32One caveat with this compiler wrapper is that it may introduce unexpected 33behaviors in incremental builds when the file path to the coverage 34instrumentation input file changes between consecutive runs, so callers of this 35script are strongly advised to always use the same path such as 36"${root_build_dir}/coverage_instrumentation_input.txt". 37 38It's worth noting on try job builders, if the contents of the instrumentation 39file changes so that a file doesn't need to be instrumented any longer, it will 40be recompiled automatically because if try job B runs after try job A, the files 41that were instrumented in A will be updated (i.e., reverted to the checked in 42version) in B, and so they'll be considered out of date by ninja and recompiled. 43 44Example usage: 45 clang_code_coverage_wrapper.py \\ 46 --files-to-instrument=coverage_instrumentation_input.txt 47""" 48 49 50import argparse 51import os 52import subprocess 53import sys 54 55# Flags used to enable coverage instrumentation. 56# Flags should be listed in the same order that they are added in 57# build/config/coverage/BUILD.gn 58_COVERAGE_FLAGS = [ 59 '-fprofile-instr-generate', 60 '-fcoverage-mapping', 61 # Following experimental flags remove unused header functions from the 62 # coverage mapping data embedded in the test binaries, and the reduction 63 # of binary size enables building Chrome's large unit test targets on 64 # MacOS. Please refer to crbug.com/796290 for more details. 65 '-mllvm', 66 '-limited-coverage-experimental=true', 67] 68 69# Files that should not be built with coverage flags by default. 70_DEFAULT_COVERAGE_EXCLUSION_LIST = [ 71 # TODO(crbug.com/1051561): angle_unittests affected by coverage. 72 '../../base/message_loop/message_pump_default.cc', 73 '../../base/message_loop/message_pump_libevent.cc', 74 '../../base/message_loop/message_pump_win.cc', 75 '../../base/task/sequence_manager/thread_controller_with_message_pump_impl.cc', #pylint: disable=line-too-long 76] 77 78# Map of exclusion lists indexed by target OS. 79# If no target OS is defined, or one is defined that doesn't have a specific 80# entry, use _DEFAULT_COVERAGE_EXCLUSION_LIST. 81_COVERAGE_EXCLUSION_LIST_MAP = { 82 'android': [ 83 # This file caused webview native library failed on arm64. 84 '../../device/gamepad/dualshock4_controller.cc', 85 ], 86 'fuchsia': [ 87 # TODO(crbug.com/1174725): These files caused clang to crash while 88 # compiling them. 89 '../../base/allocator/partition_allocator/pcscan.cc', 90 '../../third_party/skia/src/core/SkOpts.cpp', 91 '../../third_party/skia/src/opts/SkOpts_hsw.cpp', 92 '../../third_party/skia/third_party/skcms/skcms.cc', 93 ], 94 'linux': [ 95 # These files caused a static initializer to be generated, which 96 # shouldn't. 97 # TODO(crbug.com/990948): Remove when the bug is fixed. 98 '../../chrome/browser/media/router/providers/cast/cast_internal_message_util.cc', #pylint: disable=line-too-long 99 '../../components/media_router/common/providers/cast/channel/cast_channel_enum.cc', #pylint: disable=line-too-long 100 '../../components/media_router/common/providers/cast/channel/cast_message_util.cc', #pylint: disable=line-too-long 101 '../../components/media_router/common/providers/cast/cast_media_source.cc', #pylint: disable=line-too-long 102 '../../ui/events/keycodes/dom/keycode_converter.cc', 103 # TODO(crbug.com/1051561): angle_unittests affected by coverage. 104 '../../base/message_loop/message_pump_default.cc', 105 '../../base/message_loop/message_pump_libevent.cc', 106 '../../base/message_loop/message_pump_win.cc', 107 '../../base/task/sequence_manager/thread_controller_with_message_pump_impl.cc', #pylint: disable=line-too-long 108 ], 109 'chromeos': [ 110 # These files caused clang to crash while compiling them. They are 111 # excluded pending an investigation into the underlying compiler bug. 112 '../../third_party/webrtc/p2p/base/p2p_transport_channel.cc', 113 '../../third_party/icu/source/common/uts46.cpp', 114 '../../third_party/icu/source/common/ucnvmbcs.cpp', 115 '../../base/android/android_image_reader_compat.cc', 116 # TODO(crbug.com/1051561): angle_unittests affected by coverage. 117 '../../base/message_loop/message_pump_default.cc', 118 '../../base/message_loop/message_pump_libevent.cc', 119 '../../base/message_loop/message_pump_win.cc', 120 '../../base/task/sequence_manager/thread_controller_with_message_pump_impl.cc', #pylint: disable=line-too-long 121 ], 122 'win': [ 123 # TODO(crbug.com/1051561): angle_unittests affected by coverage. 124 '../../base/message_loop/message_pump_default.cc', 125 '../../base/message_loop/message_pump_libevent.cc', 126 '../../base/message_loop/message_pump_win.cc', 127 '../../base/task/sequence_manager/thread_controller_with_message_pump_impl.cc', #pylint: disable=line-too-long 128 ], 129} 130 131# Map of force lists indexed by target OS. 132_COVERAGE_FORCE_LIST_MAP = { 133 # clang_profiling.cc refers to the symbol `__llvm_profile_dump` from the 134 # profiling runtime. In a partial coverage build, it is possible for a 135 # binary to include clang_profiling.cc but have no instrumented files, thus 136 # causing an unresolved symbol error because the profiling runtime will not 137 # be linked in. Therefore we force coverage for this file to ensure that 138 # any target that includes it will also get the profiling runtime. 139 'win': [r'..\..\base\test\clang_profiling.cc'], 140 # TODO(crbug.com/1141727) We're seeing runtime LLVM errors in mac-rel when 141 # no files are changed, so we suspect that this is similar to the other 142 # problem with clang_profiling.cc on Windows. The TODO here is to force 143 # coverage for this specific file on ALL platforms, if it turns out to fix 144 # this issue on Mac as well. It's the only file that directly calls 145 # `__llvm_profile_dump` so it warrants some special treatment. 146 'mac': ['../../base/test/clang_profiling.cc'], 147} 148 149 150def _remove_flags_from_command(command): 151 # We need to remove the coverage flags for this file, but we only want to 152 # remove them if we see the exact sequence defined in _COVERAGE_FLAGS. 153 # That ensures that we only remove the flags added by GN when 154 # "use_clang_coverage" is true. Otherwise, we would remove flags set by 155 # other parts of the build system. 156 start_flag = _COVERAGE_FLAGS[0] 157 num_flags = len(_COVERAGE_FLAGS) 158 start_idx = 0 159 try: 160 while True: 161 idx = command.index(start_flag, start_idx) 162 if command[idx:idx + num_flags] == _COVERAGE_FLAGS: 163 del command[idx:idx + num_flags] 164 # There can be multiple sets of _COVERAGE_FLAGS. All of these need to be 165 # removed. 166 start_idx = idx 167 else: 168 start_idx = idx + 1 169 except ValueError: 170 pass 171 172 173def main(): 174 arg_parser = argparse.ArgumentParser() 175 arg_parser.usage = __doc__ 176 arg_parser.add_argument( 177 '--files-to-instrument', 178 type=str, 179 help='Path to a file that contains a list of file names to instrument.') 180 arg_parser.add_argument( 181 '--target-os', required=False, help='The OS to compile for.') 182 arg_parser.add_argument('args', nargs=argparse.REMAINDER) 183 parsed_args = arg_parser.parse_args() 184 185 if (parsed_args.files_to_instrument and 186 not os.path.isfile(parsed_args.files_to_instrument)): 187 raise Exception('Path to the coverage instrumentation file: "%s" doesn\'t ' 188 'exist.' % parsed_args.files_to_instrument) 189 190 compile_command = parsed_args.args 191 if not any('clang' in s for s in compile_command): 192 return subprocess.call(compile_command) 193 194 target_os = parsed_args.target_os 195 196 try: 197 # The command is assumed to use Clang as the compiler, and the path to the 198 # source file is behind the -c argument, and the path to the source path is 199 # relative to the root build directory. For example: 200 # clang++ -fvisibility=hidden -c ../../base/files/file_path.cc -o \ 201 # obj/base/base/file_path.o 202 # On Windows, clang-cl.exe uses /c instead of -c. 203 source_flag = '/c' if target_os == 'win' else '-c' 204 source_flag_index = compile_command.index(source_flag) 205 except ValueError: 206 print('%s argument is not found in the compile command.' % source_flag) 207 raise 208 209 if source_flag_index + 1 >= len(compile_command): 210 raise Exception('Source file to be compiled is missing from the command.') 211 212 # On Windows, filesystem paths should use '\', but GN creates build commands 213 # that use '/'. We invoke os.path.normpath to ensure that the path uses the 214 # correct separator for the current platform (i.e. '\' on Windows and '/' 215 # otherwise). 216 compile_source_file = os.path.normpath(compile_command[source_flag_index + 1]) 217 extension = os.path.splitext(compile_source_file)[1] 218 if not extension in ['.c', '.cc', '.cpp', '.cxx', '.m', '.mm', '.S']: 219 raise Exception('Invalid source file %s found' % compile_source_file) 220 exclusion_list = _COVERAGE_EXCLUSION_LIST_MAP.get( 221 target_os, _DEFAULT_COVERAGE_EXCLUSION_LIST) 222 force_list = _COVERAGE_FORCE_LIST_MAP.get(target_os, []) 223 224 should_remove_flags = False 225 if compile_source_file not in force_list: 226 if compile_source_file in exclusion_list: 227 should_remove_flags = True 228 elif parsed_args.files_to_instrument: 229 with open(parsed_args.files_to_instrument) as f: 230 if compile_source_file not in f.read(): 231 should_remove_flags = True 232 233 if should_remove_flags: 234 _remove_flags_from_command(compile_command) 235 236 return subprocess.call(compile_command) 237 238 239if __name__ == '__main__': 240 sys.exit(main()) 241