| #!/usr/bin/python3 |
| |
| # Copyright 2015 The Bazel Authors. All rights reserved. |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| """A script for J2ObjC dead code removal in Blaze. |
| |
| This script removes unused J2ObjC-translated classes from compilation and |
| linking by: |
| 1. Build a class dependency tree among translated source files. |
| 2. Use user-provided Java class entry points to get a list of reachable |
| classes. |
| 3. Go through all translated source files and rewrite unreachable ones with |
| dummy content. |
| """ |
| |
| import argparse |
| import collections |
| import multiprocessing |
| import os |
| import queue |
| import re |
| import shlex |
| import shutil |
| import subprocess |
| import threading |
| |
| |
| PRUNED_SRC_CONTENT = 'static int DUMMY_unused __attribute__((unused,used)) = 0;' |
| |
| |
| def BuildReachabilityTree(dependency_mapping_files, file_open=open): |
| """Builds a reachability tree using entries from dependency mapping files. |
| |
| Args: |
| dependency_mapping_files: A comma separated list of J2ObjC-generated |
| dependency mapping files. |
| file_open: Reference to the builtin open function so it may be |
| overridden for testing. |
| Returns: |
| A dict mapping J2ObjC-generated source files to the corresponding direct |
| dependent source files. |
| """ |
| return BuildArtifactSourceTree(dependency_mapping_files, file_open) |
| |
| |
| def BuildHeaderMapping(header_mapping_files, file_open=open): |
| """Builds a mapping between Java classes and J2ObjC-translated header files. |
| |
| Args: |
| header_mapping_files: A comma separated list of J2ObjC-generated |
| header mapping files. |
| file_open: Reference to the builtin open function so it may be |
| overridden for testing. |
| Returns: |
| An ordered dict mapping Java class names to corresponding J2ObjC-translated |
| source files. |
| """ |
| header_mapping = collections.OrderedDict() |
| for header_mapping_file in header_mapping_files.split(','): |
| with file_open(header_mapping_file, 'r') as f: |
| for line in f: |
| java_class_name = line.strip().split('=')[0] |
| transpiled_file_name = os.path.splitext(line.strip().split('=')[1])[0] |
| header_mapping[java_class_name] = transpiled_file_name |
| return header_mapping |
| |
| |
| def BuildReachableFileSet(entry_classes, reachability_tree, header_mapping, |
| archive_source_file_mapping=None): |
| """Builds a set of reachable translated files from entry Java classes. |
| |
| Args: |
| entry_classes: A comma separated list of Java entry classes. |
| reachability_tree: A dict mapping translated files to their direct |
| dependencies. |
| header_mapping: A dict mapping Java class names to translated source files. |
| archive_source_file_mapping: A dict mapping source files to the associated |
| archive file that contains them. |
| Returns: |
| A set of reachable translated files from the given list of entry classes. |
| Raises: |
| Exception: If there is an entry class that is not being transpiled in this |
| j2objc_library. |
| """ |
| transpiled_entry_files = [] |
| for entry_class in entry_classes.split(','): |
| if entry_class not in header_mapping: |
| raise Exception( |
| entry_class + |
| ' is not in the transitive Java deps of included ' + |
| 'j2objc_library rules.') |
| transpiled_entry_files.append(header_mapping[entry_class]) |
| |
| # Translated files going into the same static library archive with duplicated |
| # base names also need to be added to the set of entry files. |
| # |
| # This edge case is ignored because we currently cannot correctly perform |
| # dead code removal in this case. The object file entries in static library |
| # archives are named by the base names of the original source files. If two |
| # source files (e.g., foo/bar.m, bar/bar.m) go into the same archive and |
| # share the same base name (bar.m), their object file entries inside the |
| # archive will have the same name (bar.o). We cannot correctly handle this |
| # case because current archive tools (ar, ranlib, etc.) do not handle this |
| # case very well. |
| if archive_source_file_mapping: |
| transpiled_entry_files.extend(_DuplicatedFiles(archive_source_file_mapping)) |
| |
| # Translated files from package-info.java are also added to the entry files |
| # because they are needed to resolve ObjC class names with prefixes and these |
| # files may also have dependencies. |
| for transpiled_file in reachability_tree: |
| if transpiled_file.endswith('package-info'): |
| transpiled_entry_files.append(transpiled_file) |
| |
| reachable_files = set() |
| for transpiled_entry_file in transpiled_entry_files: |
| reachable_files.add(transpiled_entry_file) |
| current_level_deps = [] |
| # We need to check if the transpiled file is in the reachability tree |
| # because J2ObjC protos are not analyzed for dead code stripping and |
| # therefore are not in the reachability tree at all. |
| if transpiled_entry_file in reachability_tree: |
| current_level_deps = reachability_tree[transpiled_entry_file] |
| while current_level_deps: |
| next_level_deps = [] |
| for dep in current_level_deps: |
| if dep not in reachable_files: |
| reachable_files.add(dep) |
| if dep in reachability_tree: |
| next_level_deps.extend(reachability_tree[dep]) |
| current_level_deps = next_level_deps |
| return reachable_files |
| |
| |
| def PruneFiles(input_files, output_files, objc_file_path, reachable_files, |
| file_open=open, file_shutil=shutil): |
| """Copies over translated files and remove the contents of unreachable files. |
| |
| Args: |
| input_files: A comma separated list of input source files to prune. It has |
| a one-on-one pair mapping with the output_file list. |
| output_files: A comma separated list of output source files to write pruned |
| source files to. It has a one-on-one pair mapping with the input_file |
| list. |
| objc_file_path: The file path which represents a directory where the |
| generated ObjC files reside. |
| reachable_files: A set of reachable source files. |
| file_open: Reference to the builtin open function so it may be |
| overridden for testing. |
| file_shutil: Reference to the builtin shutil module so it may be |
| overridden for testing. |
| Returns: |
| None. |
| """ |
| file_queue = queue.queue() |
| for input_file, output_file in zip( |
| input_files.split(','), |
| output_files.split(',')): |
| file_queue.put((input_file, output_file)) |
| |
| for _ in range(multiprocessing.cpu_count()): |
| t = threading.Thread(target=_PruneFile, args=(file_queue, |
| reachable_files, |
| objc_file_path, |
| file_open, |
| file_shutil)) |
| t.start() |
| |
| file_queue.join() |
| |
| |
| def _PruneFile(file_queue, reachable_files, objc_file_path, file_open=open, |
| file_shutil=shutil): |
| while True: |
| try: |
| input_file, output_file = file_queue.get_nowait() |
| except queue.Empty: |
| return |
| file_name = os.path.relpath(os.path.splitext(input_file)[0], |
| objc_file_path) |
| if file_name in reachable_files: |
| file_shutil.copy(input_file, output_file) |
| else: |
| with file_open(output_file, 'w') as f: |
| # Use a static variable scoped to the source file to suppress |
| # the "has no symbols" linker warning for empty object files. |
| f.write(PRUNED_SRC_CONTENT) |
| file_queue.task_done() |
| |
| |
| def _DuplicatedFiles(archive_source_file_mapping): |
| """Returns a list of file with duplicated base names in each archive file. |
| |
| Args: |
| archive_source_file_mapping: A dict mapping source files to the associated |
| archive file that contains them. |
| Returns: |
| A list containing files with duplicated base names. |
| """ |
| duplicated_files = [] |
| dict_with_duplicates = dict() |
| |
| for source_files in archive_source_file_mapping.values(): |
| for source_file in source_files: |
| file_basename = os.path.basename(source_file) |
| file_without_ext = os.path.splitext(source_file)[0] |
| if file_basename in dict_with_duplicates: |
| dict_with_duplicates[file_basename].append(file_without_ext) |
| else: |
| dict_with_duplicates[file_basename] = [file_without_ext] |
| for basename in dict_with_duplicates: |
| if len(dict_with_duplicates[basename]) > 1: |
| duplicated_files.extend(dict_with_duplicates[basename]) |
| dict_with_duplicates = dict() |
| |
| return duplicated_files |
| |
| |
| def BuildArchiveSourceFileMapping(archive_source_mapping_files, file_open): |
| """Builds a mapping between archive files and their associated source files. |
| |
| Args: |
| archive_source_mapping_files: A comma separated list of J2ObjC-generated |
| mapping between archive files and their associated source files. |
| file_open: Reference to the builtin open function so it may be |
| overridden for testing. |
| Returns: |
| A dict mapping between archive files and their associated source files. |
| """ |
| return BuildArtifactSourceTree(archive_source_mapping_files, file_open) |
| |
| |
| def PruneSourceFiles(input_files, output_files, dependency_mapping_files, |
| header_mapping_files, entry_classes, objc_file_path, |
| file_open=open, file_shutil=shutil): |
| """Copies over translated files and remove the contents of unreachable files. |
| |
| Args: |
| input_files: A comma separated list of input source files to prune. It has |
| a one-on-one pair mapping with the output_file list. |
| output_files: A comma separated list of output source files to write pruned |
| source files to. It has a one-on-one pair mapping with the input_file |
| list. |
| dependency_mapping_files: A comma separated list of J2ObjC-generated |
| dependency mapping files. |
| header_mapping_files: A comma separated list of J2ObjC-generated |
| header mapping files. |
| entry_classes: A comma separated list of Java entry classes. |
| objc_file_path: The file path which represents a directory where the |
| generated ObjC files reside. |
| file_open: Reference to the builtin open function so it may be |
| overridden for testing. |
| file_shutil: Reference to the builtin shutil module so it may be |
| overridden for testing. |
| """ |
| reachability_file_mapping = BuildReachabilityTree( |
| dependency_mapping_files, file_open) |
| header_map = BuildHeaderMapping(header_mapping_files, file_open) |
| reachable_files_set = BuildReachableFileSet(entry_classes, |
| reachability_file_mapping, |
| header_map) |
| PruneFiles(input_files, |
| output_files, |
| objc_file_path, |
| reachable_files_set, |
| file_open, |
| file_shutil) |
| |
| |
| def MatchObjectNamesInArchive(xcrunwrapper, archive, object_names): |
| """Returns object names matching their identity in an archive file. |
| |
| The linker that blaze uses appends an md5 hash to object file |
| names prior to inclusion in the archive file. Thus, object names |
| such as 'foo.o' need to be matched to their appropriate name in |
| the archive file, such as 'foo_<hash>.o'. |
| |
| Args: |
| xcrunwrapper: A wrapper script over xcrun. |
| archive: The location of the archive file. |
| object_names: The expected basenames of object files to match, |
| sans extension. For example 'foo' (not 'foo.o'). |
| Returns: |
| A list of basenames of matching members of the given archive |
| """ |
| ar_contents_cmd = [xcrunwrapper, 'ar', '-t', archive] |
| real_object_names_output = subprocess.check_output(ar_contents_cmd) |
| real_object_names = real_object_names_output.decode('utf-8') |
| expected_object_name_regex = r'^(?:%s)(?:_[0-9a-f]{32}(?:-[0-9]+)?)?\.o$' % ( |
| '|'.join([re.escape(name) for name in object_names])) |
| return re.findall( |
| expected_object_name_regex, |
| real_object_names, |
| flags=re.MULTILINE) |
| |
| |
| def PruneArchiveFile(input_archive, output_archive, dummy_archive, |
| dependency_mapping_files, header_mapping_files, |
| archive_source_mapping_files, entry_classes, xcrunwrapper, |
| file_open=open): |
| """Remove unreachable objects from archive file. |
| |
| Args: |
| input_archive: The source archive file to prune. |
| output_archive: The location of the pruned archive file. |
| dummy_archive: A dummy archive file that contains no object. |
| dependency_mapping_files: A comma separated list of J2ObjC-generated |
| dependency mapping files. |
| header_mapping_files: A comma separated list of J2ObjC-generated |
| header mapping files. |
| archive_source_mapping_files: A comma separated list of J2ObjC-generated |
| mapping between archive files and their associated source files. |
| entry_classes: A comma separated list of Java entry classes. |
| xcrunwrapper: A wrapper script over xcrun. |
| file_open: Reference to the builtin open function so it may be |
| overridden for testing. |
| """ |
| reachability_file_mapping = BuildReachabilityTree( |
| dependency_mapping_files, file_open) |
| header_map = BuildHeaderMapping(header_mapping_files, file_open) |
| archive_source_file_mapping = BuildArchiveSourceFileMapping( |
| archive_source_mapping_files, file_open) |
| reachable_files_set = BuildReachableFileSet(entry_classes, |
| reachability_file_mapping, |
| header_map, |
| archive_source_file_mapping) |
| |
| # Copy the current processes' environment, as xcrunwrapper depends on these |
| # variables. |
| cmd_env = dict(os.environ) |
| j2objc_cmd = '' |
| if input_archive in archive_source_file_mapping: |
| source_files = archive_source_file_mapping[input_archive] |
| unreachable_object_names = [] |
| |
| for source_file in source_files: |
| if os.path.splitext(source_file)[0] not in reachable_files_set: |
| unreachable_object_names.append( |
| os.path.basename(os.path.splitext(source_file)[0])) |
| |
| # There are unreachable objects in the archive to prune |
| if unreachable_object_names: |
| # If all objects in the archive are unreachable, just copy over a dummy |
| # archive that contains no object |
| if len(unreachable_object_names) == len(source_files): |
| j2objc_cmd = 'cp %s %s' % (shlex.quote(dummy_archive), |
| shlex.quote(output_archive)) |
| # Else we need to prune the archive of unreachable objects |
| else: |
| cmd_env['ZERO_AR_DATE'] = '1' |
| # Copy the input archive to the output location |
| j2objc_cmd += 'cp %s %s && ' % (shlex.quote(input_archive), |
| shlex.quote(output_archive)) |
| # Make the output archive editable |
| j2objc_cmd += 'chmod +w %s && ' % (shlex.quote(output_archive)) |
| # Remove the unreachable objects from the archive |
| unreachable_object_names = MatchObjectNamesInArchive( |
| xcrunwrapper, input_archive, unreachable_object_names) |
| j2objc_cmd += '%s ar -d -s %s %s && ' % ( |
| shlex.quote(xcrunwrapper), |
| shlex.quote(output_archive), |
| ' '.join(shlex.quote(uon) for uon in unreachable_object_names)) |
| # Update the table of content of the archive file |
| j2objc_cmd += '%s ranlib %s' % (shlex.quote(xcrunwrapper), |
| shlex.quote(output_archive)) |
| # There are no unreachable objects, we just copy over the original archive |
| else: |
| j2objc_cmd = 'cp %s %s' % (shlex.quote(input_archive), |
| shlex.quote(output_archive)) |
| # The archive cannot be pruned by J2ObjC dead code removal, just copy over |
| # the original archive |
| else: |
| j2objc_cmd = 'cp %s %s' % (shlex.quote(input_archive), |
| shlex.quote(output_archive)) |
| |
| try: |
| subprocess.check_output( |
| j2objc_cmd, stderr=subprocess.STDOUT, shell=True, env=cmd_env) |
| except OSError as e: |
| raise Exception( |
| 'executing command failed: %s (%s)' % (j2objc_cmd, e.strerror)) |
| |
| # "Touch" the output file. |
| # Prevents a pre-Xcode-8 bug in which passing zero-date archive files to ld |
| # would cause ld to error. |
| os.utime(output_archive, None) |
| |
| |
| def BuildArtifactSourceTree(files, file_open=open): |
| """Builds a dependency tree using from dependency mapping files. |
| |
| Args: |
| files: A comma separated list of dependency mapping files. |
| file_open: Reference to the builtin open function so it may be overridden for |
| testing. |
| |
| Returns: |
| A dict mapping build artifacts (possibly generated source files) to the |
| corresponding direct dependent source files. |
| """ |
| tree = dict() |
| if not files: |
| return tree |
| for filename in files.split(','): |
| with file_open(filename, 'r') as f: |
| for line in f: |
| entry = line.strip().split(':')[0] |
| dep = line.strip().split(':')[1] |
| if entry in tree: |
| tree[entry].append(dep) |
| else: |
| tree[entry] = [dep] |
| return tree |
| |
| |
| if __name__ == '__main__': |
| parser = argparse.ArgumentParser(fromfile_prefix_chars='@') |
| |
| # TODO(rduan): Remove these three flags once J2ObjC compile actions are fully |
| # moved to the edges. |
| parser.add_argument( |
| '--input_files', |
| help=('The comma-separated file paths of translated source files to ' |
| 'prune.')) |
| parser.add_argument( |
| '--output_files', |
| help='The comma-separated file paths of pruned source files to write to.') |
| parser.add_argument( |
| '--objc_file_path', |
| help='The file path which represents a directory where the generated ObjC' |
| ' files reside') |
| |
| parser.add_argument( |
| '--input_archive', |
| help=('The path of the translated archive to prune.')) |
| parser.add_argument( |
| '--output_archive', |
| help='The path of the pruned archive file to write to.') |
| parser.add_argument( |
| '--dummy_archive', |
| help='The dummy archive file that contains no symbol.') |
| parser.add_argument( |
| '--dependency_mapping_files', |
| help='The comma-separated file paths of dependency mapping files.') |
| parser.add_argument( |
| '--header_mapping_files', |
| help='The comma-separated file paths of header mapping files.') |
| parser.add_argument( |
| '--archive_source_mapping_files', |
| help='The comma-separated file paths of archive to source mapping files.' |
| 'These mapping files should contain mappings between the ' |
| 'translated source files and the archive file compiled from those ' |
| 'source files.') |
| parser.add_argument( |
| '--entry_classes', |
| help=('The comma-separated list of Java entry classes to be used as entry' |
| ' point of the dead code analysis.')) |
| parser.add_argument( |
| '--xcrunwrapper', |
| help=('The xcrun wrapper script.')) |
| |
| args = parser.parse_args() |
| |
| if not args.entry_classes: |
| raise Exception('J2objC dead code removal is on but no entry class is ', |
| 'specified in any j2objc_library targets in the transitive', |
| ' closure') |
| if args.input_archive and args.output_archive: |
| PruneArchiveFile( |
| args.input_archive, |
| args.output_archive, |
| args.dummy_archive, |
| args.dependency_mapping_files, |
| args.header_mapping_files, |
| args.archive_source_mapping_files, |
| args.entry_classes, |
| args.xcrunwrapper) |
| else: |
| # TODO(rduan): Remove once J2ObjC compile actions are fully moved to the |
| # edges. |
| PruneSourceFiles( |
| args.input_files, |
| args.output_files, |
| args.dependency_mapping_files, |
| args.header_mapping_files, |
| args.entry_classes, |
| args.objc_file_path) |
