Replace flutter --build-snapshot with --precompile that takes input (#20574)

packages/flutter_tools/gradle/flutter.gradle

@@ -300,9 +300,9 @@ class FlutterPlugin implements Plugin<Project> {
         if (project.hasProperty('track-widget-creation')) {
             trackWidgetCreationValue = project.property('track-widget-creation').toBoolean()
         }
-        Boolean buildSnapshotValue = false
-        if (project.hasProperty('build-snapshot')) {
-            buildSnapshotValue = project.property('build-snapshot').toBoolean()
+        String compilationTraceFilePathValue = null
+        if (project.hasProperty('precompile')) {
+            compilationTraceFilePathValue = project.property('precompile')
         }
         String extraFrontEndOptionsValue = null
         if (project.hasProperty('extra-front-end-options')) {
@@ -346,7 +346,7 @@ class FlutterPlugin implements Plugin<Project> {
                 fileSystemRoots fileSystemRootsValue
                 fileSystemScheme fileSystemSchemeValue
                 trackWidgetCreation trackWidgetCreationValue
-                buildSnapshot buildSnapshotValue
+                compilationTraceFilePath compilationTraceFilePathValue
                 buildSharedLibrary buildSharedLibraryValue
                 targetPlatform targetPlatformValue
                 sourceDir project.file(project.flutter.source)
@@ -396,7 +396,7 @@ abstract class BaseFlutterTask extends DefaultTask {
     @Optional @Input
     Boolean trackWidgetCreation
     @Optional @Input
-    Boolean buildSnapshot
+    String compilationTraceFilePath
     @Optional @Input
     Boolean buildSharedLibrary
     @Optional @Input
@@ -500,8 +500,8 @@ abstract class BaseFlutterTask extends DefaultTask {
             if (trackWidgetCreation) {
                 args "--track-widget-creation"
             }
-            if (buildSnapshot) {
-                args "--build-snapshot"
+            if (compilationTraceFilePath != null) {
+                args "--precompile", compilationTraceFilePath
             }
             if (extraFrontEndOptions != null) {
                 args "--extra-front-end-options", "${extraFrontEndOptions}"
@@ -549,7 +549,7 @@ class FlutterTask extends BaseFlutterTask {
 
             include "flutter_assets/**" // the working dir and its files
 
-            if (buildMode != 'debug' || buildSnapshot) {
+            if (buildMode != 'debug' || compilationTraceFilePath) {
                 if (buildSharedLibrary) {
                     include "app.so"
                 } else {

packages/flutter_tools/lib/src/android/gradle.dart

@@ -357,8 +357,8 @@ Future<Null> _buildGradleProjectV2(
     command.add('-Ppreview-dart-2=true');
     if (buildInfo.trackWidgetCreation)
       command.add('-Ptrack-widget-creation=true');
-    if (buildInfo.buildSnapshot)
-      command.add('-Pbuild-snapshot=true');
+    if (buildInfo.compilationTraceFilePath != null)
+      command.add('-Pprecompile=${buildInfo.compilationTraceFilePath}');
     if (buildInfo.extraFrontEndOptions != null)
       command.add('-Pextra-front-end-options=${buildInfo.extraFrontEndOptions}');
     if (buildInfo.extraGenSnapshotOptions != null)

packages/flutter_tools/lib/src/base/build.dart

@@ -427,6 +427,7 @@ class CoreJITSnapshotter {
     @required String mainPath,
     @required String packagesPath,
     @required String outputPath,
+    @required String compilationTraceFilePath,
     List<String> extraGenSnapshotOptions = const <String>[],
   }) async {
     if (!_isValidCoreJitPlatform(platform)) {
@@ -437,7 +438,7 @@ class CoreJITSnapshotter {
     final Directory outputDir = fs.directory(outputPath);
     outputDir.createSync(recursive: true);
 
-    final List<String> inputPaths = <String>[mainPath];
+    final List<String> inputPaths = <String>[mainPath, compilationTraceFilePath];
     final Set<String> outputPaths = new Set<String>();
 
     final String depfilePath = fs.path.join(outputDir.path, 'snapshot.d');
@@ -466,7 +467,7 @@ class CoreJITSnapshotter {
       '--isolate_snapshot_data=$isolateSnapshotData',
       '--vm_snapshot_instructions=$vmSnapshotInstructions',
       '--isolate_snapshot_instructions=$isolateSnapshotInstructions',
-      '--load_compilation_trace=trace.txt',
+      '--load_compilation_trace=$compilationTraceFilePath',
     ]);
 
     if (platform == TargetPlatform.android_arm) {

packages/flutter_tools/lib/src/build_info.dart

@@ -13,7 +13,7 @@ class BuildInfo {
   const BuildInfo(this.mode, this.flavor, {
     this.previewDart2 = false,
     this.trackWidgetCreation = false,
-    this.buildSnapshot = false,
+    this.compilationTraceFilePath,
     this.extraFrontEndOptions,
     this.extraGenSnapshotOptions,
     this.buildSharedLibrary,
@@ -43,8 +43,8 @@ class BuildInfo {
   /// Whether the build should track widget creation locations.
   final bool trackWidgetCreation;
 
-  /// Whether the build should create VM snapshot instead of using prebuilt one from engine.
-  final bool buildSnapshot;
+  /// Dart compilation trace file to use for JIT VM snapshot.
+  final String compilationTraceFilePath;
 
   /// Extra command-line options for front-end.
   final String extraFrontEndOptions;
@@ -101,7 +101,7 @@ class BuildInfo {
       new BuildInfo(mode, flavor,
           previewDart2: previewDart2,
           trackWidgetCreation: trackWidgetCreation,
-          buildSnapshot: buildSnapshot,
+          compilationTraceFilePath: compilationTraceFilePath,
           extraFrontEndOptions: extraFrontEndOptions,
           extraGenSnapshotOptions: extraGenSnapshotOptions,
           buildSharedLibrary: buildSharedLibrary,

packages/flutter_tools/lib/src/bundle.dart

@@ -47,7 +47,7 @@ Future<void> build({
   bool precompiledSnapshot = false,
   bool reportLicensedPackages = false,
   bool trackWidgetCreation = false,
-  bool buildSnapshot = false,
+  String compilationTraceFilePath,
   List<String> extraFrontEndOptions = const <String>[],
   List<String> extraGenSnapshotOptions = const <String>[],
   List<String> fileSystemRoots,
@@ -84,7 +84,7 @@ Future<void> build({
     ensureDirectoryExists(applicationKernelFilePath);
     final CompilerOutput compilerOutput = await kernelCompiler.compile(
       sdkRoot: artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath),
-      incrementalCompilerByteStorePath: buildSnapshot ? null :
+      incrementalCompilerByteStorePath: compilationTraceFilePath != null ? null :
           fs.path.absolute(getIncrementalCompilerByteStoreDirectory()),
       mainPath: fs.file(mainPath).absolute.path,
       outputFilePath: applicationKernelFilePath,
@@ -94,7 +94,7 @@ Future<void> build({
       fileSystemRoots: fileSystemRoots,
       fileSystemScheme: fileSystemScheme,
       packagesPath: packagesPath,
-      linkPlatformKernelIn: buildSnapshot,
+      linkPlatformKernelIn: compilationTraceFilePath != null,
     );
     if (compilerOutput?.outputFilename == null) {
       throwToolExit('Compiler failed on $mainPath');
@@ -104,7 +104,7 @@ Future<void> build({
     await fs.directory(getBuildDirectory()).childFile('frontend_server.d')
         .writeAsString('frontend_server.d: ${artifacts.getArtifactPath(Artifact.frontendServerSnapshotForEngineDartSdk)}\n');
 
-    if (buildSnapshot) {
+    if (compilationTraceFilePath != null) {
       final CoreJITSnapshotter snapshotter = new CoreJITSnapshotter();
       final int snapshotExitCode = await snapshotter.build(
         platform: platform,
@@ -112,6 +112,7 @@ Future<void> build({
         mainPath: applicationKernelFilePath,
         outputPath: getBuildDirectory(),
         packagesPath: packagesPath,
+        compilationTraceFilePath: compilationTraceFilePath,
         extraGenSnapshotOptions: extraGenSnapshotOptions,
       );
       if (snapshotExitCode != 0) {
@@ -135,7 +136,7 @@ Future<void> build({
     snapshotFile: snapshotFile,
     privateKeyPath: privateKeyPath,
     assetDirPath: assetDirPath,
-    buildSnapshot: buildSnapshot,
+    compilationTraceFilePath: compilationTraceFilePath,
   );
 }
 
@@ -171,14 +172,14 @@ Future<void> assemble({
   File dylibFile,
   String privateKeyPath = defaultPrivateKeyPath,
   String assetDirPath,
-  bool buildSnapshot,
+  String compilationTraceFilePath,
 }) async {
   assetDirPath ??= getAssetBuildDirectory();
   printTrace('Building bundle');
 
   final Map<String, DevFSContent> assetEntries = new Map<String, DevFSContent>.from(assetBundle.entries);
   if (kernelContent != null) {
-    if (buildSnapshot) {
+    if (compilationTraceFilePath != null) {
       final String vmSnapshotData = fs.path.join(getBuildDirectory(), _kVMSnapshotData);
       final String vmSnapshotInstr = fs.path.join(getBuildDirectory(), _kVMSnapshotInstr);
       final String isolateSnapshotData = fs.path.join(getBuildDirectory(), _kIsolateSnapshotData);

packages/flutter_tools/lib/src/commands/build_bundle.dart

@@ -37,11 +37,14 @@ class BuildBundleCommand extends BuildSubCommand {
         hide: !verboseHelp,
         help: 'Track widget creation locations. Requires Dart 2.0 functionality.',
       )
-      ..addFlag('build-snapshot',
+      ..addOption('precompile',
         hide: !verboseHelp,
-        defaultsTo: false,
-        help: 'Build and use application-specific VM snapshot instead of\n'
-            'prebuilt one provided by the engine.',
+        help: 'Precompile functions specified in input file. This flag is only\n'
+              'allowed when using --dynamic. It takes a Dart compilation trace\n'
+              'file produced by the training run of the application. With this\n'
+              'flag, instead of using default Dart VM snapshot provided by the\n'
+              'engine, the application will use its own snapshot that includes\n'
+              'additional functions.'
       )
       ..addMultiOption(FlutterOptions.kExtraFrontEndOptions,
         splitCommas: true,
@@ -106,7 +109,7 @@ class BuildBundleCommand extends BuildSubCommand {
       precompiledSnapshot: argResults['precompiled'],
       reportLicensedPackages: argResults['report-licensed-packages'],
       trackWidgetCreation: argResults['track-widget-creation'],
-      buildSnapshot: argResults['build-snapshot'],
+      compilationTraceFilePath: argResults['precompile'],
       extraFrontEndOptions: argResults[FlutterOptions.kExtraFrontEndOptions],
       extraGenSnapshotOptions: argResults[FlutterOptions.kExtraGenSnapshotOptions],
       fileSystemScheme: argResults['filesystem-scheme'],

packages/flutter_tools/lib/src/commands/run.dart

@@ -124,11 +124,14 @@ class RunCommand extends RunCommandBase {
         hide: !verboseHelp,
         help: 'Preview Dart 2.0 functionality.',
       )
-      ..addFlag('build-snapshot',
+      ..addOption('precompile',
         hide: !verboseHelp,
-        defaultsTo: false,
-        help: 'Build and use application-specific VM snapshot instead of\n'
-              'prebuilt one provided by the engine.',
+        help: 'Precompile functions specified in input file. This flag is only\n'
+              'allowed when using --dynamic. It takes a Dart compilation trace\n'
+              'file produced by the training run of the application. With this\n'
+              'flag, instead of using default Dart VM snapshot provided by the\n'
+              'engine, the application will use its own snapshot that includes\n'
+              'additional functions.'
       )
       ..addFlag('track-widget-creation',
         hide: !verboseHelp,

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -224,9 +224,9 @@ abstract class FlutterCommand extends Command<Null> {
         : null,
       previewDart2: previewDart2,
       trackWidgetCreation: trackWidgetCreation,
-      buildSnapshot: argParser.options.containsKey('build-snapshot')
-          ? argResults['build-snapshot']
-          : false,
+      compilationTraceFilePath: argParser.options.containsKey('precompile')
+          ? argResults['precompile']
+          : null,
       extraFrontEndOptions: argParser.options.containsKey(FlutterOptions.kExtraFrontEndOptions)
           ? argResults[FlutterOptions.kExtraFrontEndOptions]
           : null,
@@ -474,6 +474,15 @@ abstract class FlutterCommand extends Command<Null> {
       if (!fs.isFileSync(targetPath))
         throw new ToolExit('Target file "$targetPath" not found.');
     }
+
+    final bool dynamicFlag = argParser.options.containsKey('dynamic')
+        ? argResults['dynamic'] : false;
+    final String compilationTraceFilePath = argParser.options.containsKey('precompile')
+        ? argResults['precompile'] : null;
+    if (compilationTraceFilePath != null && getBuildMode() == BuildMode.debug)
+      throw new ToolExit('Error: --precompile is not allowed when --debug is specified.');
+    if (compilationTraceFilePath != null && !dynamicFlag)
+      throw new ToolExit('Error: --precompile is allowed only when --dynamic is specified.');
   }
 
   ApplicationPackageStore applicationPackages;

packages/flutter_tools/test/base/build_test.dart

@@ -813,6 +813,7 @@ void main() {
         mainPath: 'main.dill',
         packagesPath: '.packages',
         outputPath: outputPath,
+        compilationTraceFilePath: kTrace,
       ), isNot(equals(0)));
     }, overrides: contextOverrides);
 
@@ -836,6 +837,7 @@ void main() {
         mainPath: 'main.dill',
         packagesPath: '.packages',
         outputPath: outputPath,
+        compilationTraceFilePath: kTrace,
       );
 
       expect(genSnapshotExitCode, 0);
@@ -880,6 +882,7 @@ void main() {
         mainPath: 'main.dill',
         packagesPath: '.packages',
         outputPath: outputPath,
+        compilationTraceFilePath: kTrace,
       );
 
       expect(genSnapshotExitCode, 0);
@@ -910,6 +913,7 @@ void main() {
         mainPath: 'main.dill',
         packagesPath: '.packages',
         outputPath: outputPath,
+        compilationTraceFilePath: kTrace,
       ), isNot(equals(0)));
     }, overrides: contextOverrides);
 
@@ -933,6 +937,7 @@ void main() {
         mainPath: 'main.dill',
         packagesPath: '.packages',
         outputPath: outputPath,
+        compilationTraceFilePath: kTrace,
       );
 
       expect(genSnapshotExitCode, 0);
@@ -976,6 +981,7 @@ void main() {
         mainPath: 'main.dill',
         packagesPath: '.packages',
         outputPath: outputPath,
+        compilationTraceFilePath: kTrace,
       );
 
       expect(genSnapshotExitCode, 0);
@@ -1005,6 +1011,7 @@ void main() {
         mainPath: 'main.dill',
         packagesPath: '.packages',
         outputPath: outputPath,
+        compilationTraceFilePath: kTrace,
       ), isNot(equals(0)));
     }, overrides: contextOverrides);
 
@@ -1028,6 +1035,7 @@ void main() {
         mainPath: 'main.dill',
         packagesPath: '.packages',
         outputPath: outputPath,
+        compilationTraceFilePath: kTrace,
       );
 
       expect(genSnapshotExitCode, 0);
@@ -1071,6 +1079,7 @@ void main() {
         mainPath: 'main.dill',
         packagesPath: '.packages',
         outputPath: outputPath,
+        compilationTraceFilePath: kTrace,
       );
 
       expect(genSnapshotExitCode, 0);