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MarkzipanMarkzipan
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Set --no-js-strongly-connected-components for DDC compiles by default (#193485)
Context: DDC's old module system was sensitive to load order, so mutual/cyclic imports needed to be combined into a single 'module' (using a strongly-connected-components/SCC algorithm in our various build infrastructure). DDC's new Library Bundle module system doesn't have this restriction, so we can safely disable SCCs. The net result is that every library emits one JS artifact, which helps us avoid problems with overly large connected components causing parse deoptimizations in Chrome/V8. More artifacts are emitted (so perhaps higher compile time), but the overall load time is improved - especially for larger apps. Resolves some of the performance degradations reported in: #192687
1 parent d4c0acd commit b297796

3 files changed

Lines changed: 30 additions & 5 deletions

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‎packages/flutter_tools/lib/src/compile.dart‎

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@@ -28,6 +28,13 @@ import 'dart/package_map.dart';
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/// Opt-in changes to the dart compilers.
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const kDartCompilerExperiments = <String>[];
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// Flags passed when compiling with DDC.
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const kDdcLibraryBundleFlags = <String>[
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'--dartdevc-module-format=ddc',
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'--dartdevc-canary',
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'--no-js-strongly-connected-components',
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];
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/// The target model describes the set of core libraries that are available within
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/// the SDK.
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class TargetModel {
@@ -567,9 +574,7 @@ class ResidentCompilerFactory {
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fileSystemScheme: 'org-dartlang-app',
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extraFrontEndOptions: [
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...buildInfo.extraFrontEndOptions,
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if (buildInfo.webEnableHotReload)
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// These flags are only valid to be passed when compiling with DDC.
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...<String>['--dartdevc-canary', '--dartdevc-module-format=ddc'],
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if (buildInfo.webEnableHotReload) ...kDdcLibraryBundleFlags,
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],
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);
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} else {

‎packages/flutter_tools/test/general.shard/compile_test.dart‎

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@@ -349,4 +349,26 @@ void main() {
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// match.
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await completer.future.timeout(const Duration(seconds: 5));
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});
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testWithoutContext('ResidentCompilerFactory configures DDC library bundle flags', () {
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final compiler = const ResidentCompilerFactory().create(
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targetPlatform: .web_javascript,
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buildInfo: const BuildInfo(
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BuildMode.debug,
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null,
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treeShakeIcons: false,
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packageConfigPath: '.dart_tool/package_config.json',
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webEnableHotReload: true,
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),
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logger: BufferLogger.test(),
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processManager: FakeProcessManager.any(),
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artifacts: Artifacts.test(),
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platform: FakePlatform(),
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fileSystem: MemoryFileSystem.test(),
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shutdownHooks: FakeShutdownHooks(),
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config: Config.test(),
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) as DefaultResidentCompiler;
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expect(compiler.extraFrontEndOptions, containsAll(kDdcLibraryBundleFlags));
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});
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}

‎packages/flutter_tools/test/general.shard/resident_web_runner_test.dart‎

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@@ -94,8 +94,6 @@ const kStartPausedAndAttachExpectations = <VmServiceExpectation>[
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...kAttachIsolateExpectations,
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];
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const kDdcLibraryBundleFlags = <String>['--dartdevc-module-format=ddc', '--dartdevc-canary'];
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void main() {
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late FakeDebugConnection debugConnection;
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late FakeChromeDevice chromeDevice;

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