blob: 3af79b601760c54591fb6d19fac10319a37cb305 [file] [log] [blame]
#!/usr/bin/env dart
// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
/// This program will take a .dill file and do a protobuf aware tree-shaking.
/// All fields of GeneratedMessage subclasses that are not accessed with their
/// getter or setter will have their metadata removed from the class definition.
/// Then a general treeshaking will be run, and
/// all GeneratedMessage subclasses that are never used directly will be
/// removed.
/// The processed program will have observable differences: The tree-shaken
/// fields will be parsed as unknown fields.
/// The toString method will treat the unknown fields as missing.
/// Using the `GeneratedMessage.info_` field to reflect on fields will have
/// unpredictable behavior.
/// Constants are evaluated, this is mainly to enable detecting
/// `@pragma('vm:entry-point')`.
library vm.protobuf_aware_treeshaker;
import 'dart:async';
import 'dart:io';
import 'dart:typed_data';
import 'package:args/args.dart';
import 'package:kernel/kernel.dart';
import 'package:kernel/binary/ast_to_binary.dart';
import 'package:kernel/core_types.dart' show CoreTypes;
import 'package:vm/kernel_front_end.dart'
show runGlobalTransformations, ErrorDetector;
import 'package:kernel/target/targets.dart' show TargetFlags, getTarget;
import 'package:vm/target/install.dart' show installAdditionalTargets;
import 'package:vm/transformations/type_flow/transformer.dart' as globalTypeFlow
show transformComponent;
ArgResults parseArgs(List<String> args) {
ArgParser argParser = ArgParser()
valueHelp: "path/to/vm_platform.dill",
help: 'A platform.dill file to append to the input. If not given, no '
'platform.dill will be appended.')
allowed: ['dart_runner', 'flutter', 'flutter-runner', 'vm'],
defaultsTo: 'vm',
help: 'Target platform.')
help: 'If set, produces kernel file for AOT compilation (enables '
'global transformations). Otherwise, writes regular dill.',
defaultsTo: false)
help: 'Also write the result in kernel-text format as <out.dill>.txt',
defaultsTo: false)
help: 'If set, the output dill file will not include `dart:` libraries',
defaultsTo: false)
abbr: 'D',
help: 'Perform constant evaluation with this environment define set.',
valueHelp: 'variable=value')
help: 'Removes source code from the emitted dill', defaultsTo: false)
help: 'Write to stdout about what classes and fields where remeoved')
..addFlag('help', help: 'Prints this help', negatable: false);
ArgResults? argResults;
try {
argResults = argParser.parse(args);
} on FormatException catch (e) {
if (argResults == null || argResults['help'] || != 2) {
String script = 'protobuf_aware_treeshaker.dart';
'A tool for removing protobuf messages types that are never referred by a program');
print('Usage: $script [args] <input.dill> <output.dill>');
if (argResults['aot'] && argResults['remove-core-libs']) {
print('The `--aot` option is incompatible with `--remove-core-libs`');
return argResults;
Future main(List<String> args) async {
ArgResults argResults = parseArgs(args);
final input =[0];
final output =[1];
var bytes = File(input).readAsBytesSync();
final platformFile = argResults['platform'];
if (platformFile != null) {
bytes = concatenate(File(platformFile).readAsBytesSync(), bytes);
final component = loadComponentFromBytes(bytes);
final target = getTarget(argResults['target'], TargetFlags())!;
// The [component] is treeshaken and has TFA annotations. Write output.
if (argResults['aot']) {
const bool useGlobalTypeFlowAnalysis = true;
const bool enableAsserts = false;
const bool useProtobufAwareTreeShakerV2 = true;
final nopErrorDetector = ErrorDetector();
} else {
globalTypeFlow.transformComponent(target, CoreTypes(component), component,
treeShakeProtobufs: true, treeShakeSignatures: false);
if (argResults['aot']) {
// Write kernel file for AOT compilation.
final sink = File(output).openWrite();
final printer = BinaryPrinter(sink);
await sink.close();
} else {
// Clean out the AOT-only TFA annotations and write regular dill.
await writeComponent(component, output,
removeCoreLibs: argResults['remove-core-libs'],
removeSource: argResults['remove-source']);
if (argResults['write-txt']) {
writeComponentToText(component, path: output + '.txt');
Uint8List concatenate(Uint8List a, Uint8List b) {
final bytes = Uint8List(a.length + b.length);
bytes.setRange(0, a.length, a);
bytes.setRange(a.length, a.length + b.length, b);
return bytes;
Future writeComponent(Component component, String filename,
{required bool removeCoreLibs, required bool removeSource}) async {
if (removeSource) {
for (final lib in component.libraries) {
final sink = File(filename).openWrite();
final printer = BinaryPrinter(sink, libraryFilter: (lib) {
if (removeCoreLibs && isCoreLibrary(lib)) return false;
if (isLibEmpty(lib)) return false;
return true;
}, includeSources: !removeSource);
await sink.close();
bool isLibEmpty(Library lib) {
return lib.classes.isEmpty &&
lib.procedures.isEmpty &&
lib.fields.isEmpty &&
bool isCoreLibrary(Library library) {
return library.importUri.scheme == 'dart';