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were instrumented in A will be updated (i.e., reverted to the checked in 42version) in B, and so they'll be considered out of date by ninja and recompiled. 43 44Example usage: 45 clang_code_coverage_wrapper.py \\ 46 --files-to-instrument=coverage_instrumentation_input.txt 47 48Siso implements the same logic in 49build/config/siso/clang_code_coverage_wrapper.star, which avoids the wrapper 50invocations for remote execution and performance improvement. 51Please update the Siso starlark file when updating this file. 52""" 53# LINT.IfChange 54 55import argparse 56import os 57import subprocess 58import sys 59 60# Flags used to enable coverage instrumentation. 61# Flags should be listed in the same order that they are added in 62# build/config/coverage/BUILD.gn 63_COVERAGE_FLAGS = [ 64 '-fprofile-instr-generate', 65 '-fcoverage-mapping', 66 '-mllvm', 67 '-runtime-counter-relocation=true', 68 # Following experimental flags remove unused header functions from the 69 # coverage mapping data embedded in the test binaries, and the reduction 70 # of binary size enables building Chrome's large unit test targets on 71 # MacOS. Please refer to crbug.com/796290 for more details. 72 '-mllvm', 73 '-limited-coverage-experimental=true', 74] 75 76# Files that should not be built with coverage flags by default. 77_DEFAULT_COVERAGE_EXCLUSION_LIST = [] 78 79# Map of exclusion lists indexed by target OS. 80# If no target OS is defined, or one is defined that doesn't have a specific 81# entry, use _DEFAULT_COVERAGE_EXCLUSION_LIST. 82_COVERAGE_EXCLUSION_LIST_MAP = { 83 'android': [ 84 # This file caused webview native library failed on arm64. 85 '../../device/gamepad/dualshock4_controller.cc', 86 ], 87 'fuchsia': [ 88 # TODO(crbug.com/1174725): These files caused clang to crash while 89 # compiling them. 90 '../../base/allocator/partition_allocator/src/partition_alloc/pcscan.cc', 91 '../../third_party/skia/src/core/SkOpts.cpp', 92 '../../third_party/skia/src/opts/SkOpts_hsw.cpp', 93 '../../third_party/skia/third_party/skcms/skcms.cc', 94 ], 95 'linux': [ 96 # These files caused a static initializer to be generated, which 97 # shouldn't. 98 # TODO(crbug.com/990948): Remove when the bug is fixed. 99 '../../chrome/browser/media/router/providers/cast/cast_internal_message_util.cc', #pylint: disable=line-too-long 100 '../../components/media_router/common/providers/cast/channel/cast_channel_enum.cc', #pylint: disable=line-too-long 101 '../../components/media_router/common/providers/cast/channel/cast_message_util.cc', #pylint: disable=line-too-long 102 '../../components/media_router/common/providers/cast/cast_media_source.cc', #pylint: disable=line-too-long 103 '../../ui/events/keycodes/dom/keycode_converter.cc', 104 ], 105 'chromeos': [ 106 # These files caused clang to crash while compiling them. They are 107 # excluded pending an investigation into the underlying compiler bug. 108 '../../third_party/webrtc/p2p/base/p2p_transport_channel.cc', 109 '../../third_party/icu/source/common/uts46.cpp', 110 '../../third_party/icu/source/common/ucnvmbcs.cpp', 111 '../../base/android/android_image_reader_compat.cc', 112 ], 113} 114 115# Map of force lists indexed by target OS. 116_COVERAGE_FORCE_LIST_MAP = { 117 # clang_profiling.cc refers to the symbol `__llvm_profile_dump` from the 118 # profiling runtime. In a partial coverage build, it is possible for a 119 # binary to include clang_profiling.cc but have no instrumented files, thus 120 # causing an unresolved symbol error because the profiling runtime will not 121 # be linked in. Therefore we force coverage for this file to ensure that 122 # any target that includes it will also get the profiling runtime. 123 'win': [r'..\..\base\test\clang_profiling.cc'], 124 # TODO(crbug.com/1141727) We're seeing runtime LLVM errors in mac-rel when 125 # no files are changed, so we suspect that this is similar to the other 126 # problem with clang_profiling.cc on Windows. The TODO here is to force 127 # coverage for this specific file on ALL platforms, if it turns out to fix 128 # this issue on Mac as well. It's the only file that directly calls 129 # `__llvm_profile_dump` so it warrants some special treatment. 130 'mac': ['../../base/test/clang_profiling.cc'], 131} 132 133 134def _remove_flags_from_command(command): 135 # We need to remove the coverage flags for this file, but we only want to 136 # remove them if we see the exact sequence defined in _COVERAGE_FLAGS. 137 # That ensures that we only remove the flags added by GN when 138 # "use_clang_coverage" is true. Otherwise, we would remove flags set by 139 # other parts of the build system. 140 start_flag = _COVERAGE_FLAGS[0] 141 num_flags = len(_COVERAGE_FLAGS) 142 start_idx = 0 143 try: 144 while True: 145 idx = command.index(start_flag, start_idx) 146 if command[idx:idx + num_flags] == _COVERAGE_FLAGS: 147 del command[idx:idx + num_flags] 148 # There can be multiple sets of _COVERAGE_FLAGS. All of these need to be 149 # removed. 150 start_idx = idx 151 else: 152 start_idx = idx + 1 153 except ValueError: 154 pass 155 156 157def main(): 158 arg_parser = argparse.ArgumentParser() 159 arg_parser.usage = __doc__ 160 arg_parser.add_argument( 161 '--files-to-instrument', 162 type=str, 163 help='Path to a file that contains a list of file names to instrument.') 164 arg_parser.add_argument( 165 '--target-os', required=False, help='The OS to compile for.') 166 arg_parser.add_argument('args', nargs=argparse.REMAINDER) 167 parsed_args = arg_parser.parse_args() 168 169 if (parsed_args.files_to_instrument and 170 not os.path.isfile(parsed_args.files_to_instrument)): 171 raise Exception('Path to the coverage instrumentation file: "%s" doesn\'t ' 172 'exist.' % parsed_args.files_to_instrument) 173 174 compile_command = parsed_args.args 175 if not any('clang' in s for s in compile_command): 176 return subprocess.call(compile_command) 177 178 target_os = parsed_args.target_os 179 180 try: 181 # The command is assumed to use Clang as the compiler, and the path to the 182 # source file is behind the -c argument, and the path to the source path is 183 # relative to the root build directory. For example: 184 # clang++ -fvisibility=hidden -c ../../base/files/file_path.cc -o \ 185 # obj/base/base/file_path.o 186 # On Windows, clang-cl.exe uses /c instead of -c. 187 source_flag = '/c' if target_os == 'win' else '-c' 188 source_flag_index = compile_command.index(source_flag) 189 except ValueError: 190 print('%s argument is not found in the compile command.' % source_flag) 191 raise 192 193 if source_flag_index + 1 >= len(compile_command): 194 raise Exception('Source file to be compiled is missing from the command.') 195 196 # On Windows, filesystem paths should use '\', but GN creates build commands 197 # that use '/'. We invoke os.path.normpath to ensure that the path uses the 198 # correct separator for the current platform (i.e. '\' on Windows and '/' 199 # otherwise). 200 compile_source_file = os.path.normpath(compile_command[source_flag_index + 1]) 201 extension = os.path.splitext(compile_source_file)[1] 202 if not extension in ['.c', '.cc', '.cpp', '.cxx', '.m', '.mm', '.S']: 203 raise Exception('Invalid source file %s found' % compile_source_file) 204 exclusion_list = _COVERAGE_EXCLUSION_LIST_MAP.get( 205 target_os, _DEFAULT_COVERAGE_EXCLUSION_LIST) 206 force_list = _COVERAGE_FORCE_LIST_MAP.get(target_os, []) 207 208 should_remove_flags = False 209 if compile_source_file not in force_list: 210 if compile_source_file in exclusion_list: 211 should_remove_flags = True 212 elif parsed_args.files_to_instrument: 213 with open(parsed_args.files_to_instrument) as f: 214 if compile_source_file not in f.read(): 215 should_remove_flags = True 216 217 if should_remove_flags: 218 _remove_flags_from_command(compile_command) 219 220 return subprocess.call(compile_command) 221 222 223if __name__ == '__main__': 224 sys.exit(main()) 225 226# LINT.ThenChange(/build/config/siso/clang_code_coverage_wrapper.star) 227