Make FrontendServerClient start the frontend server from AOT snapshot by default

frontend_server_client/CHANGELOG.md

@@ -1,7 +1,12 @@
-## 3.3.0-wip
+## 4.0.0-wip
 
-- Update Dart SDK constraint to `>=3.0.0 <4.0.0`.
+- Update Dart SDK constraint to `^3.0.0`.
 - Support changes in the SDK layout for Dart 3.0.
+- By default, start the frontend server from the AOT snapshot shipped in the
+  Dart SDK.
+- Throw an `ArgumentError` when `FrontendServerClient.start` is called with the
+  `frontendServerPath` argument omitted and the `debug` argument set to true.
+- Update `package:vm_service` constraint to `^14.0.0`.
 
 ## 3.2.0
 

frontend_server_client/lib/src/frontend_server_client.dart

@@ -40,6 +40,15 @@ class FrontendServerClient {
   /// The [outputDillPath] determines where the primary output should be, and
   /// some targets may output additional files based on that file name (by
   /// adding file extensions for instance).
+  ///
+  /// When the [frontendServerPath] argument is provided, the frontend server
+  /// will be started from the specified file. The specified file can either be
+  /// a Dart source file or an AppJIT snapshot.
+  ///
+  /// When the [frontendServerPath] argument is provided, setting [debug] to
+  /// true permits debuggers to attach to the frontend server. When the
+  /// [frontendServerPath] argument is omitted, setting [debug] to true will
+  /// cause an [ArgumentError] to be thrown.
   static Future<FrontendServerClient> start(
     String entrypoint,
     String outputDillPath,
@@ -60,9 +69,7 @@ class FrontendServerClient {
     List<String> additionalSources = const [],
     String? nativeAssets,
   }) async {
-    var feServer = await Process.start(Platform.resolvedExecutable, [
-      if (debug) '--observe',
-      frontendServerPath ?? _feServerPath,
+    final commonArguments = <String>[
       '--sdk-root',
       sdkRoot ?? sdkDir,
       '--platform=$platformKernel',
@@ -90,7 +97,38 @@ class FrontendServerClient {
         '--native-assets',
         nativeAssets,
       ],
-    ]);
+    ];
+    late final Process feServer;
+    if (frontendServerPath != null) {
+      feServer = await Process.start(
+        Platform.resolvedExecutable,
+        <String>[
+          if (debug) '--observe',
+          frontendServerPath,
+          ...commonArguments,
+        ],
+      );
+    } else if (File(_feServerAotSnapshotPath).existsSync()) {
+      if (debug) {
+        throw ArgumentError('The debug argument cannot be set to true when the '
+            'frontendServerPath argument is omitted.');
+      }
+      feServer = await Process.start(
+        _dartAotRuntimePath,
+        <String>[_feServerAotSnapshotPath, ...commonArguments],
+      );
+    } else {
+      // AOT snapshots cannot be generated on IA32, so we need this fallback
+      // branch until support for IA32 is dropped (https://dartbug.com/49969).
+      feServer = await Process.start(
+        Platform.resolvedExecutable,
+        <String>[
+          if (debug) '--observe',
+          _feServerAppJitSnapshotPath,
+          ...commonArguments,
+        ],
+      );
+    }
     var feServerStdoutLines = StreamQueue(feServer.stdout
         .transform(utf8.decoder)
         .transform(const LineSplitter()));
@@ -407,5 +445,10 @@ enum _RejectState {
   done,
 }
 
-final _feServerPath =
+final _dartAotRuntimePath = p.join(sdkDir, 'bin', 'dartaotruntime');
+
+final _feServerAppJitSnapshotPath =
     p.join(sdkDir, 'bin', 'snapshots', 'frontend_server.dart.snapshot');
+
+final _feServerAotSnapshotPath =
+    p.join(sdkDir, 'bin', 'snapshots', 'frontend_server_aot.dart.snapshot');

frontend_server_client/pubspec.yaml

@@ -1,5 +1,5 @@
 name: frontend_server_client
-version: 3.3.0-wip
+version: 4.0.0-wip
 description: >-
   Client code to start and interact with the frontend_server compiler from the
   Dart SDK.
@@ -20,4 +20,4 @@ dev_dependencies:
   test: ^1.16.0
   test_descriptor: ^2.0.0
   test_process: ^2.0.0
-  vm_service: ^8.0.0
+  vm_service: ^14.0.0

frontend_server_common/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.2.2
+
+- Start the frontend server from the AOT snapshot shipped in the Dart SDK.
+
 ## 0.2.1
 
 - Doe not pass `-debugger-module-names` flag to the frontend server.

frontend_server_common/lib/src/frontend_server_client.dart

@@ -398,7 +398,7 @@ class ResidentCompiler {
 
     _logger.info(args.join(' '));
     final workingDirectory = projectDirectory.toFilePath();
-    _server = await Process.start(sdkLayout.dartPath, args,
+    _server = await Process.start(sdkLayout.dartAotRuntimePath, args,
         workingDirectory: workingDirectory);
 
     var server = _server!;

test_common/lib/test_sdk_layout.dart

@@ -90,11 +90,16 @@ class TestSdkLayout {
           'bin',
           Platform.isWindows ? 'dart.exe' : 'dart',
         ),
+        dartAotRuntimePath: p.join(
+          sdkLayout.sdkDirectory,
+          'bin',
+          Platform.isWindows ? 'dartaotruntime.exe' : 'dartaotruntime',
+        ),
         frontendServerSnapshotPath: p.join(
           sdkLayout.sdkDirectory,
           'bin',
           'snapshots',
-          'frontend_server.dart.snapshot',
+          'frontend_server_aot.dart.snapshot',
         ),
         dartdevcSnapshotPath: sdkLayout.dartdevcSnapshotPath,
         kernelWorkerSnapshotPath: p.join(
@@ -137,6 +142,7 @@ class TestSdkLayout {
   final String stackTraceMapperPath;
 
   final String dartPath;
+  final String dartAotRuntimePath;
   final String frontendServerSnapshotPath;
   final String dartdevcSnapshotPath;
   final String kernelWorkerSnapshotPath;
@@ -155,6 +161,7 @@ class TestSdkLayout {
     required this.requireJsPath,
     required this.stackTraceMapperPath,
     required this.dartPath,
+    required this.dartAotRuntimePath,
     required this.frontendServerSnapshotPath,
     required this.dartdevcSnapshotPath,
     required this.kernelWorkerSnapshotPath,

test_common/test/test_sdk_configuration_test.dart

@@ -70,6 +70,7 @@ void main() {
       expect(sdkLayout.stackTraceMapperPath, _fileExists);
 
       expect(sdkLayout.dartPath, _fileExists);
+      expect(sdkLayout.dartAotRuntimePath, _fileExists);
       expect(sdkLayout.frontendServerSnapshotPath, _fileExists);
       expect(sdkLayout.dartdevcSnapshotPath, _fileExists);
       expect(sdkLayout.kernelWorkerSnapshotPath, _fileExists);