packages/flutter_tools/lib/src/base/build.dart - external/github.com/flutter/flutter - Git at Google

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'dart:async';

 import 'package:meta/meta.dart';

 import '../android/android_sdk.dart';
 import '../artifacts.dart';
 import '../build_info.dart';
 import '../compile.dart';
 import '../dart/package_map.dart';
 import '../globals.dart';
 import '../ios/mac.dart';
 import 'context.dart';
 import 'file_system.dart';
 import 'fingerprint.dart';
 import 'process.dart';

 GenSnapshot get genSnapshot => context[GenSnapshot];

 /// A snapshot build configuration.
 class SnapshotType {
   SnapshotType(this.platform, this.mode)
     : assert(mode != null);

   final TargetPlatform platform;
   final BuildMode mode;

   @override
   String toString() => '$platform $mode';
 }

 /// Interface to the gen_snapshot command-line tool.
 class GenSnapshot {
   const GenSnapshot();

   static String getSnapshotterPath(SnapshotType snapshotType) {
     return artifacts.getArtifactPath(
         Artifact.genSnapshot, snapshotType.platform, snapshotType.mode);
   }

   Future<int> run({
     @required SnapshotType snapshotType,
     @required String packagesPath,
     IOSArch iosArch,
     Iterable<String> additionalArgs = const <String>[],
   }) {
     final List<String> args = <String>[
       '--await_is_keyword',
       '--causal_async_stacks',
       '--packages=$packagesPath',
     ]..addAll(additionalArgs);

     final String snapshotterPath = getSnapshotterPath(snapshotType);

     // iOS gen_snapshot is a multi-arch binary. Running as an i386 binary will
     // generate armv7 code. Running as an x86_64 binary will generate arm64
     // code. /usr/bin/arch can be used to run binaries with the specified
     // architecture.
     if (snapshotType.platform == TargetPlatform.ios) {
       final String hostArch = iosArch == IOSArch.armv7 ? '-i386' : '-x86_64';
       return runCommandAndStreamOutput(<String>['/usr/bin/arch', hostArch, snapshotterPath]..addAll(args));
     }
     return runCommandAndStreamOutput(<String>[snapshotterPath]..addAll(args));
   }
 }

 class AOTSnapshotter {
   /// Builds an architecture-specific ahead-of-time compiled snapshot of the specified script.
   Future<int> build({
     @required TargetPlatform platform,
     @required BuildMode buildMode,
     @required String mainPath,
     @required String packagesPath,
     @required String outputPath,
     @required bool buildSharedLibrary,
     IOSArch iosArch,
     List<String> extraGenSnapshotOptions = const <String>[],
   }) async {
     if (!_isValidAotPlatform(platform, buildMode)) {
       printError('${getNameForTargetPlatform(platform)} does not support AOT compilation.');
       return 1;
     }
     // TODO(cbracken): replace IOSArch with TargetPlatform.ios_{armv7,arm64}.
     assert(platform != TargetPlatform.ios || iosArch != null);

     // buildSharedLibrary is ignored for iOS builds.
     if (platform == TargetPlatform.ios)
       buildSharedLibrary = false;

     if (buildSharedLibrary && androidSdk.ndk == null) {
       final String explanation = AndroidNdk.explainMissingNdk(androidSdk.directory);
       printError(
         'Could not find NDK in Android SDK at ${androidSdk.directory}:\n'
         '\n'
         '  $explanation\n'
         '\n'
         'Unable to build with --build-shared-library\n'
         'To install the NDK, see instructions at https://developer.android.com/ndk/guides/'
       );
       return 1;
     }

     final PackageMap packageMap = new PackageMap(packagesPath);
     final String packageMapError = packageMap.checkValid();
     if (packageMapError != null) {
       printError(packageMapError);
       return 1;
     }

     final Directory outputDir = fs.directory(outputPath);
     outputDir.createSync(recursive: true);

     final String skyEnginePkg = _getPackagePath(packageMap, 'sky_engine');
     final String uiPath = fs.path.join(skyEnginePkg, 'lib', 'ui', 'ui.dart');
     final String vmServicePath = fs.path.join(skyEnginePkg, 'sdk_ext', 'vmservice_io.dart');
     final String vmEntryPoints = artifacts.getArtifactPath(Artifact.dartVmEntryPointsTxt, platform, buildMode);
     final String ioEntryPoints = artifacts.getArtifactPath(Artifact.dartIoEntriesTxt, platform, buildMode);

     final List<String> inputPaths = <String>[uiPath, vmServicePath, vmEntryPoints, ioEntryPoints, mainPath];
     final Set<String> outputPaths = new Set<String>();

     final String depfilePath = fs.path.join(outputDir.path, 'snapshot.d');
     final List<String> genSnapshotArgs = <String>[
       '--url_mapping=dart:ui,$uiPath',
       '--url_mapping=dart:vmservice_io,$vmServicePath',
       '--embedder_entry_points_manifest=$vmEntryPoints',
       '--embedder_entry_points_manifest=$ioEntryPoints',
     ];
     genSnapshotArgs.addAll(<String>[
       '--reify-generic-functions',
       '--strong',
       '--sync-async',
     ]);
     if (extraGenSnapshotOptions != null && extraGenSnapshotOptions.isNotEmpty) {
       printTrace('Extra gen_snapshot options: $extraGenSnapshotOptions');
       genSnapshotArgs.addAll(extraGenSnapshotOptions);
     }

     final String assembly = fs.path.join(outputDir.path, 'snapshot_assembly.S');
     if (buildSharedLibrary || platform == TargetPlatform.ios) {
       // Assembly AOT snapshot.
       outputPaths.add(assembly);
       genSnapshotArgs.add('--snapshot_kind=app-aot-assembly');
       genSnapshotArgs.add('--assembly=$assembly');
     } else {
       // Blob AOT snapshot.
       final String vmSnapshotData = fs.path.join(outputDir.path, 'vm_snapshot_data');
       final String isolateSnapshotData = fs.path.join(outputDir.path, 'isolate_snapshot_data');
       final String vmSnapshotInstructions = fs.path.join(outputDir.path, 'vm_snapshot_instr');
       final String isolateSnapshotInstructions = fs.path.join(outputDir.path, 'isolate_snapshot_instr');
       outputPaths.addAll(<String>[vmSnapshotData, isolateSnapshotData, vmSnapshotInstructions, isolateSnapshotInstructions]);
       genSnapshotArgs.addAll(<String>[
         '--snapshot_kind=app-aot-blobs',
         '--vm_snapshot_data=$vmSnapshotData',
         '--isolate_snapshot_data=$isolateSnapshotData',
         '--vm_snapshot_instructions=$vmSnapshotInstructions',
         '--isolate_snapshot_instructions=$isolateSnapshotInstructions',
       ]);
     }

     if (platform == TargetPlatform.android_arm || iosArch == IOSArch.armv7) {
       // Use softfp for Android armv7 devices.
       // Note that this is the default for armv7 iOS builds, but harmless to set.
       // TODO(cbracken): eliminate this when we fix https://github.com/flutter/flutter/issues/17489
       genSnapshotArgs.add('--no-sim-use-hardfp');

       // Not supported by the Pixel in 32-bit mode.
       genSnapshotArgs.add('--no-use-integer-division');
     }

     genSnapshotArgs.add(mainPath);

     // Verify that all required inputs exist.
     final Iterable<String> missingInputs = inputPaths.where((String p) => !fs.isFileSync(p));
     if (missingInputs.isNotEmpty) {
       printError('Missing input files: $missingInputs from $inputPaths');
       return 1;
     }

     // If inputs and outputs have not changed since last run, skip the build.
     final Fingerprinter fingerprinter = new Fingerprinter(
       fingerprintPath: '$depfilePath.fingerprint',
       paths: <String>[mainPath]..addAll(inputPaths)..addAll(outputPaths),
       properties: <String, String>{
         'buildMode': buildMode.toString(),
         'targetPlatform': platform.toString(),
         'entryPoint': mainPath,
         'sharedLib': buildSharedLibrary.toString(),
         'extraGenSnapshotOptions': extraGenSnapshotOptions.join(' '),
       },
       depfilePaths: <String>[],
     );
     if (await fingerprinter.doesFingerprintMatch()) {
       printTrace('Skipping AOT snapshot build. Fingerprint match.');
       return 0;
     }

     final SnapshotType snapshotType = new SnapshotType(platform, buildMode);
     final int genSnapshotExitCode = await genSnapshot.run(
       snapshotType: snapshotType,
       packagesPath: packageMap.packagesPath,
       additionalArgs: genSnapshotArgs,
       iosArch: iosArch,
     );
     if (genSnapshotExitCode != 0) {
       printError('Dart snapshot generator failed with exit code $genSnapshotExitCode');
       return genSnapshotExitCode;
     }

     // Write path to gen_snapshot, since snapshots have to be re-generated when we roll
     // the Dart SDK.
     final String genSnapshotPath = GenSnapshot.getSnapshotterPath(snapshotType);
     await outputDir.childFile('gen_snapshot.d').writeAsString('gen_snapshot.d: $genSnapshotPath\n');

     // On iOS, we use Xcode to compile the snapshot into a dynamic library that the
     // end-developer can link into their app.
     if (platform == TargetPlatform.ios) {
       final RunResult result = await _buildIosFramework(iosArch: iosArch, assemblyPath: assembly, outputPath: outputDir.path);
       if (result.exitCode != 0)
         return result.exitCode;
     } else if (buildSharedLibrary) {
       final RunResult result = await _buildAndroidSharedLibrary(assemblyPath: assembly, outputPath: outputDir.path);
       if (result.exitCode != 0) {
         printError('Failed to build AOT snapshot. Compiler terminated with exit code ${result.exitCode}');
         return result.exitCode;
       }
     }

     // Compute and record build fingerprint.
     await fingerprinter.writeFingerprint();
     return 0;
   }

   /// Builds an iOS framework at [outputPath]/App.framework from the assembly
   /// source at [assemblyPath].
   Future<RunResult> _buildIosFramework({
     @required IOSArch iosArch,
     @required String assemblyPath,
     @required String outputPath,
   }) async {
     final String targetArch = iosArch == IOSArch.armv7 ? 'armv7' : 'arm64';
     printStatus('Building App.framework for $targetArch...');
     final List<String> commonBuildOptions = <String>['-arch', targetArch, '-miphoneos-version-min=8.0'];

     final String assemblyO = fs.path.join(outputPath, 'snapshot_assembly.o');
     final RunResult compileResult = await xcode.cc(commonBuildOptions.toList()..addAll(<String>['-c', assemblyPath, '-o', assemblyO]));
     if (compileResult.exitCode != 0) {
       printError('Failed to compile AOT snapshot. Compiler terminated with exit code ${compileResult.exitCode}');
       return compileResult;
     }

     final String frameworkDir = fs.path.join(outputPath, 'App.framework');
     fs.directory(frameworkDir).createSync(recursive: true);
     final String appLib = fs.path.join(frameworkDir, 'App');
     final List<String> linkArgs = commonBuildOptions.toList()..addAll(<String>[
         '-dynamiclib',
         '-Xlinker', '-rpath', '-Xlinker', '@executable_path/Frameworks',
         '-Xlinker', '-rpath', '-Xlinker', '@loader_path/Frameworks',
         '-install_name', '@rpath/App.framework/App',
         '-o', appLib,
         assemblyO,
     ]);
     final RunResult linkResult = await xcode.clang(linkArgs);
     if (linkResult.exitCode != 0) {
       printError('Failed to link AOT snapshot. Linker terminated with exit code ${compileResult.exitCode}');
     }
     return linkResult;
   }

   /// Builds an Android shared library at [outputPath]/app.so from the assembly
   /// source at [assemblyPath].
   Future<RunResult> _buildAndroidSharedLibrary({
     @required String assemblyPath,
     @required String outputPath,
   }) async {
     // A word of warning: Instead of compiling via two steps, to a .o file and
     // then to a .so file we use only one command. When using two commands
     // gcc will end up putting a .eh_frame and a .debug_frame into the shared
     // library. Without stripping .debug_frame afterwards, unwinding tools
     // based upon libunwind use just one and ignore the contents of the other
     // (which causes it to not look into the other section and therefore not
     // find the correct unwinding information).
     final String assemblySo = fs.path.join(outputPath, 'app.so');
     return await runCheckedAsync(<String>[androidSdk.ndk.compiler]
         ..addAll(androidSdk.ndk.compilerArgs)
         ..addAll(<String>[ '-shared', '-nostdlib', '-o', assemblySo, assemblyPath ]));
   }

   /// Compiles a Dart file to kernel.
   ///
   /// Returns the output kernel file path, or null on failure.
   Future<String> compileKernel({
     @required TargetPlatform platform,
     @required BuildMode buildMode,
     @required String mainPath,
     @required String outputPath,
     List<String> extraFrontEndOptions = const <String>[],
   }) async {
     final Directory outputDir = fs.directory(outputPath);
     outputDir.createSync(recursive: true);

     printTrace('Compiling Dart to kernel: $mainPath');
     final List<String> entryPointsJsonFiles = <String>[
       artifacts.getArtifactPath(Artifact.entryPointsJson, platform, buildMode),
       artifacts.getArtifactPath(Artifact.entryPointsExtraJson, platform, buildMode),
     ];

     if ((extraFrontEndOptions != null) && extraFrontEndOptions.isNotEmpty)
       printTrace('Extra front-end options: $extraFrontEndOptions');

     final String depfilePath = fs.path.join(outputPath, 'kernel_compile.d');
     final CompilerOutput compilerOutput = await kernelCompiler.compile(
       sdkRoot: artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath),
       mainPath: mainPath,
       outputFilePath: fs.path.join(outputPath, 'app.dill'),
       depFilePath: depfilePath,
       extraFrontEndOptions: extraFrontEndOptions,
       linkPlatformKernelIn: true,
       aot: true,
       entryPointsJsonFiles: entryPointsJsonFiles,
       trackWidgetCreation: false,
       targetProductVm: buildMode == BuildMode.release,
     );

     // Write path to frontend_server, since things need to be re-generated when that changes.
     final String frontendPath = artifacts.getArtifactPath(Artifact.frontendServerSnapshotForEngineDartSdk);
     await fs.directory(outputPath).childFile('frontend_server.d').writeAsString('frontend_server.d: $frontendPath\n');

     return compilerOutput?.outputFilename;
   }

   bool _isValidAotPlatform(TargetPlatform platform, BuildMode buildMode) {
     if (buildMode == BuildMode.debug)
       return false;
     return const <TargetPlatform>[
       TargetPlatform.android_arm,
       TargetPlatform.android_arm64,
       TargetPlatform.ios,
     ].contains(platform);
   }

   String _getPackagePath(PackageMap packageMap, String package) {
     return fs.path.dirname(fs.path.fromUri(packageMap.map[package]));
   }
 }

 class CoreJITSnapshotter {
   /// Builds a "Core JIT" VM snapshot of the specified kernel. This snapshot
   /// includes data as well as either machine code or DBC, depending on build
   /// configuration.
   Future<int> build({
     @required TargetPlatform platform,
     @required BuildMode buildMode,
     @required String mainPath,
     @required String packagesPath,
     @required String outputPath,
     @required String compilationTraceFilePath,
     List<String> extraGenSnapshotOptions = const <String>[],
   }) async {
     if (!_isValidCoreJitPlatform(platform)) {
       printError('${getNameForTargetPlatform(platform)} does not support Core JIT compilation.');
       return 1;
     }

     final Directory outputDir = fs.directory(outputPath);
     outputDir.createSync(recursive: true);

     final List<String> inputPaths = <String>[mainPath, compilationTraceFilePath];
     final Set<String> outputPaths = new Set<String>();

     final String depfilePath = fs.path.join(outputDir.path, 'snapshot.d');
     final List<String> genSnapshotArgs = <String>[
       '--reify-generic-functions',
       '--strong',
       '--sync-async',
     ];
     if (buildMode == BuildMode.debug) {
       genSnapshotArgs.add('--enable_asserts');
     }
     if (extraGenSnapshotOptions != null && extraGenSnapshotOptions.isNotEmpty) {
       printTrace('Extra gen_snapshot options: $extraGenSnapshotOptions');
       genSnapshotArgs.addAll(extraGenSnapshotOptions);
     }

     // Blob Core JIT snapshot.
     final String vmSnapshotData = fs.path.join(outputDir.path, 'vm_snapshot_data');
     final String isolateSnapshotData = fs.path.join(outputDir.path, 'isolate_snapshot_data');
     final String vmSnapshotInstructions = fs.path.join(outputDir.path, 'vm_snapshot_instr');
     final String isolateSnapshotInstructions = fs.path.join(outputDir.path, 'isolate_snapshot_instr');
     outputPaths.addAll(<String>[vmSnapshotData, isolateSnapshotData, vmSnapshotInstructions, isolateSnapshotInstructions]);
     genSnapshotArgs.addAll(<String>[
       '--snapshot_kind=core-jit',
       '--vm_snapshot_data=$vmSnapshotData',
       '--isolate_snapshot_data=$isolateSnapshotData',
       '--vm_snapshot_instructions=$vmSnapshotInstructions',
       '--isolate_snapshot_instructions=$isolateSnapshotInstructions',
       '--load_compilation_trace=$compilationTraceFilePath',
     ]);

     if (platform == TargetPlatform.android_arm) {
       // Use softfp for Android armv7 devices.
       // TODO(cbracken): eliminate this when we fix https://github.com/flutter/flutter/issues/17489
       genSnapshotArgs.add('--no-sim-use-hardfp');

       // Not supported by the Pixel in 32-bit mode.
       genSnapshotArgs.add('--no-use-integer-division');
     }

     genSnapshotArgs.add(mainPath);

     // Verify that all required inputs exist.
     final Iterable<String> missingInputs = inputPaths.where((String p) => !fs.isFileSync(p));
     if (missingInputs.isNotEmpty) {
       printError('Missing input files: $missingInputs from $inputPaths');
       return 1;
     }

     // If inputs and outputs have not changed since last run, skip the build.
     final Fingerprinter fingerprinter = new Fingerprinter(
       fingerprintPath: '$depfilePath.fingerprint',
       paths: <String>[mainPath]..addAll(inputPaths)..addAll(outputPaths),
       properties: <String, String>{
         'buildMode': buildMode.toString(),
         'targetPlatform': platform.toString(),
         'entryPoint': mainPath,
         'extraGenSnapshotOptions': extraGenSnapshotOptions.join(' '),
       },
       depfilePaths: <String>[],
     );
     if (await fingerprinter.doesFingerprintMatch()) {
       printTrace('Skipping Core JIT snapshot build. Fingerprint match.');
       return 0;
     }

     final SnapshotType snapshotType = new SnapshotType(platform, buildMode);
     final int genSnapshotExitCode = await genSnapshot.run(
       snapshotType: snapshotType,
       packagesPath: packagesPath,
       additionalArgs: genSnapshotArgs,
     );
     if (genSnapshotExitCode != 0) {
       printError('Dart snapshot generator failed with exit code $genSnapshotExitCode');
       return genSnapshotExitCode;
     }

     // Write path to gen_snapshot, since snapshots have to be re-generated when we roll
     // the Dart SDK.
     final String genSnapshotPath = GenSnapshot.getSnapshotterPath(snapshotType);
     await outputDir.childFile('gen_snapshot.d').writeAsString('gen_snapshot.d: $genSnapshotPath\n');

     // Compute and record build fingerprint.
     await fingerprinter.writeFingerprint();
     return 0;
   }

   bool _isValidCoreJitPlatform(TargetPlatform platform) {
     return const <TargetPlatform>[
       TargetPlatform.android_arm,
       TargetPlatform.android_arm64,
     ].contains(platform);
   }
 }
	// Copyright 2017 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'dart:async';

	import 'package:meta/meta.dart';

	import '../android/android_sdk.dart';
	import '../artifacts.dart';
	import '../build_info.dart';
	import '../compile.dart';
	import '../dart/package_map.dart';
	import '../globals.dart';
	import '../ios/mac.dart';
	import 'context.dart';
	import 'file_system.dart';
	import 'fingerprint.dart';
	import 'process.dart';

	GenSnapshot get genSnapshot => context[GenSnapshot];

	/// A snapshot build configuration.
	class SnapshotType {
	SnapshotType(this.platform, this.mode)
	: assert(mode != null);

	final TargetPlatform platform;
	final BuildMode mode;

	@override
	String toString() => '$platform $mode';
	}

	/// Interface to the gen_snapshot command-line tool.
	class GenSnapshot {
	const GenSnapshot();

	static String getSnapshotterPath(SnapshotType snapshotType) {
	return artifacts.getArtifactPath(
	Artifact.genSnapshot, snapshotType.platform, snapshotType.mode);
	}

	Future<int> run({
	@required SnapshotType snapshotType,
	@required String packagesPath,
	IOSArch iosArch,
	Iterable<String> additionalArgs = const <String>[],
	}) {
	final List<String> args = <String>[
	'--await_is_keyword',
	'--causal_async_stacks',
	'--packages=$packagesPath',
	]..addAll(additionalArgs);

	final String snapshotterPath = getSnapshotterPath(snapshotType);

	// iOS gen_snapshot is a multi-arch binary. Running as an i386 binary will
	// generate armv7 code. Running as an x86_64 binary will generate arm64
	// code. /usr/bin/arch can be used to run binaries with the specified
	// architecture.
	if (snapshotType.platform == TargetPlatform.ios) {
	final String hostArch = iosArch == IOSArch.armv7 ? '-i386' : '-x86_64';
	return runCommandAndStreamOutput(<String>['/usr/bin/arch', hostArch, snapshotterPath]..addAll(args));
	}
	return runCommandAndStreamOutput(<String>[snapshotterPath]..addAll(args));
	}
	}

	class AOTSnapshotter {
	/// Builds an architecture-specific ahead-of-time compiled snapshot of the specified script.
	Future<int> build({
	@required TargetPlatform platform,
	@required BuildMode buildMode,
	@required String mainPath,
	@required String packagesPath,
	@required String outputPath,
	@required bool buildSharedLibrary,
	IOSArch iosArch,
	List<String> extraGenSnapshotOptions = const <String>[],
	}) async {
	if (!_isValidAotPlatform(platform, buildMode)) {
	printError('${getNameForTargetPlatform(platform)} does not support AOT compilation.');
	return 1;
	}
	// TODO(cbracken): replace IOSArch with TargetPlatform.ios_{armv7,arm64}.
	assert(platform != TargetPlatform.ios \|\| iosArch != null);

	// buildSharedLibrary is ignored for iOS builds.
	if (platform == TargetPlatform.ios)
	buildSharedLibrary = false;

	if (buildSharedLibrary && androidSdk.ndk == null) {
	final String explanation = AndroidNdk.explainMissingNdk(androidSdk.directory);
	printError(
	'Could not find NDK in Android SDK at ${androidSdk.directory}:\n'
	'\n'
	' $explanation\n'
	'\n'
	'Unable to build with --build-shared-library\n'
	'To install the NDK, see instructions at https://developer.android.com/ndk/guides/'
	);
	return 1;
	}

	final PackageMap packageMap = new PackageMap(packagesPath);
	final String packageMapError = packageMap.checkValid();
	if (packageMapError != null) {
	printError(packageMapError);
	return 1;
	}

	final Directory outputDir = fs.directory(outputPath);
	outputDir.createSync(recursive: true);

	final String skyEnginePkg = _getPackagePath(packageMap, 'sky_engine');
	final String uiPath = fs.path.join(skyEnginePkg, 'lib', 'ui', 'ui.dart');
	final String vmServicePath = fs.path.join(skyEnginePkg, 'sdk_ext', 'vmservice_io.dart');
	final String vmEntryPoints = artifacts.getArtifactPath(Artifact.dartVmEntryPointsTxt, platform, buildMode);
	final String ioEntryPoints = artifacts.getArtifactPath(Artifact.dartIoEntriesTxt, platform, buildMode);

	final List<String> inputPaths = <String>[uiPath, vmServicePath, vmEntryPoints, ioEntryPoints, mainPath];
	final Set<String> outputPaths = new Set<String>();

	final String depfilePath = fs.path.join(outputDir.path, 'snapshot.d');
	final List<String> genSnapshotArgs = <String>[
	'--url_mapping=dart:ui,$uiPath',
	'--url_mapping=dart:vmservice_io,$vmServicePath',
	'--embedder_entry_points_manifest=$vmEntryPoints',
	'--embedder_entry_points_manifest=$ioEntryPoints',
	];
	genSnapshotArgs.addAll(<String>[
	'--reify-generic-functions',
	'--strong',
	'--sync-async',
	]);
	if (extraGenSnapshotOptions != null && extraGenSnapshotOptions.isNotEmpty) {
	printTrace('Extra gen_snapshot options: $extraGenSnapshotOptions');
	genSnapshotArgs.addAll(extraGenSnapshotOptions);
	}

	final String assembly = fs.path.join(outputDir.path, 'snapshot_assembly.S');
	if (buildSharedLibrary \|\| platform == TargetPlatform.ios) {
	// Assembly AOT snapshot.
	outputPaths.add(assembly);
	genSnapshotArgs.add('--snapshot_kind=app-aot-assembly');
	genSnapshotArgs.add('--assembly=$assembly');
	} else {
	// Blob AOT snapshot.
	final String vmSnapshotData = fs.path.join(outputDir.path, 'vm_snapshot_data');
	final String isolateSnapshotData = fs.path.join(outputDir.path, 'isolate_snapshot_data');
	final String vmSnapshotInstructions = fs.path.join(outputDir.path, 'vm_snapshot_instr');
	final String isolateSnapshotInstructions = fs.path.join(outputDir.path, 'isolate_snapshot_instr');
	outputPaths.addAll(<String>[vmSnapshotData, isolateSnapshotData, vmSnapshotInstructions, isolateSnapshotInstructions]);
	genSnapshotArgs.addAll(<String>[
	'--snapshot_kind=app-aot-blobs',
	'--vm_snapshot_data=$vmSnapshotData',
	'--isolate_snapshot_data=$isolateSnapshotData',
	'--vm_snapshot_instructions=$vmSnapshotInstructions',
	'--isolate_snapshot_instructions=$isolateSnapshotInstructions',
	]);
	}

	if (platform == TargetPlatform.android_arm \|\| iosArch == IOSArch.armv7) {
	// Use softfp for Android armv7 devices.
	// Note that this is the default for armv7 iOS builds, but harmless to set.
	// TODO(cbracken): eliminate this when we fix https://github.com/flutter/flutter/issues/17489
	genSnapshotArgs.add('--no-sim-use-hardfp');

	// Not supported by the Pixel in 32-bit mode.
	genSnapshotArgs.add('--no-use-integer-division');
	}

	genSnapshotArgs.add(mainPath);

	// Verify that all required inputs exist.
	final Iterable<String> missingInputs = inputPaths.where((String p) => !fs.isFileSync(p));
	if (missingInputs.isNotEmpty) {
	printError('Missing input files: $missingInputs from $inputPaths');
	return 1;
	}

	// If inputs and outputs have not changed since last run, skip the build.
	final Fingerprinter fingerprinter = new Fingerprinter(
	fingerprintPath: '$depfilePath.fingerprint',
	paths: <String>[mainPath]..addAll(inputPaths)..addAll(outputPaths),
	properties: <String, String>{
	'buildMode': buildMode.toString(),
	'targetPlatform': platform.toString(),
	'entryPoint': mainPath,
	'sharedLib': buildSharedLibrary.toString(),
	'extraGenSnapshotOptions': extraGenSnapshotOptions.join(' '),
	},
	depfilePaths: <String>[],
	);
	if (await fingerprinter.doesFingerprintMatch()) {
	printTrace('Skipping AOT snapshot build. Fingerprint match.');
	return 0;
	}

	final SnapshotType snapshotType = new SnapshotType(platform, buildMode);
	final int genSnapshotExitCode = await genSnapshot.run(
	snapshotType: snapshotType,
	packagesPath: packageMap.packagesPath,
	additionalArgs: genSnapshotArgs,
	iosArch: iosArch,
	);
	if (genSnapshotExitCode != 0) {
	printError('Dart snapshot generator failed with exit code $genSnapshotExitCode');
	return genSnapshotExitCode;
	}

	// Write path to gen_snapshot, since snapshots have to be re-generated when we roll
	// the Dart SDK.
	final String genSnapshotPath = GenSnapshot.getSnapshotterPath(snapshotType);
	await outputDir.childFile('gen_snapshot.d').writeAsString('gen_snapshot.d: $genSnapshotPath\n');

	// On iOS, we use Xcode to compile the snapshot into a dynamic library that the
	// end-developer can link into their app.
	if (platform == TargetPlatform.ios) {
	final RunResult result = await _buildIosFramework(iosArch: iosArch, assemblyPath: assembly, outputPath: outputDir.path);
	if (result.exitCode != 0)
	return result.exitCode;
	} else if (buildSharedLibrary) {
	final RunResult result = await _buildAndroidSharedLibrary(assemblyPath: assembly, outputPath: outputDir.path);
	if (result.exitCode != 0) {
	printError('Failed to build AOT snapshot. Compiler terminated with exit code ${result.exitCode}');
	return result.exitCode;
	}
	}

	// Compute and record build fingerprint.
	await fingerprinter.writeFingerprint();
	return 0;
	}

	/// Builds an iOS framework at [outputPath]/App.framework from the assembly
	/// source at [assemblyPath].
	Future<RunResult> _buildIosFramework({
	@required IOSArch iosArch,
	@required String assemblyPath,
	@required String outputPath,
	}) async {
	final String targetArch = iosArch == IOSArch.armv7 ? 'armv7' : 'arm64';
	printStatus('Building App.framework for $targetArch...');
	final List<String> commonBuildOptions = <String>['-arch', targetArch, '-miphoneos-version-min=8.0'];

	final String assemblyO = fs.path.join(outputPath, 'snapshot_assembly.o');
	final RunResult compileResult = await xcode.cc(commonBuildOptions.toList()..addAll(<String>['-c', assemblyPath, '-o', assemblyO]));
	if (compileResult.exitCode != 0) {
	printError('Failed to compile AOT snapshot. Compiler terminated with exit code ${compileResult.exitCode}');
	return compileResult;
	}

	final String frameworkDir = fs.path.join(outputPath, 'App.framework');
	fs.directory(frameworkDir).createSync(recursive: true);
	final String appLib = fs.path.join(frameworkDir, 'App');
	final List<String> linkArgs = commonBuildOptions.toList()..addAll(<String>[
	'-dynamiclib',
	'-Xlinker', '-rpath', '-Xlinker', '@executable_path/Frameworks',
	'-Xlinker', '-rpath', '-Xlinker', '@loader_path/Frameworks',
	'-install_name', '@rpath/App.framework/App',
	'-o', appLib,
	assemblyO,
	]);
	final RunResult linkResult = await xcode.clang(linkArgs);
	if (linkResult.exitCode != 0) {
	printError('Failed to link AOT snapshot. Linker terminated with exit code ${compileResult.exitCode}');
	}
	return linkResult;
	}

	/// Builds an Android shared library at [outputPath]/app.so from the assembly
	/// source at [assemblyPath].
	Future<RunResult> _buildAndroidSharedLibrary({
	@required String assemblyPath,
	@required String outputPath,
	}) async {
	// A word of warning: Instead of compiling via two steps, to a .o file and
	// then to a .so file we use only one command. When using two commands
	// gcc will end up putting a .eh_frame and a .debug_frame into the shared
	// library. Without stripping .debug_frame afterwards, unwinding tools
	// based upon libunwind use just one and ignore the contents of the other
	// (which causes it to not look into the other section and therefore not
	// find the correct unwinding information).
	final String assemblySo = fs.path.join(outputPath, 'app.so');
	return await runCheckedAsync(<String>[androidSdk.ndk.compiler]
	..addAll(androidSdk.ndk.compilerArgs)
	..addAll(<String>[ '-shared', '-nostdlib', '-o', assemblySo, assemblyPath ]));
	}

	/// Compiles a Dart file to kernel.
	///
	/// Returns the output kernel file path, or null on failure.
	Future<String> compileKernel({
	@required TargetPlatform platform,
	@required BuildMode buildMode,
	@required String mainPath,
	@required String outputPath,
	List<String> extraFrontEndOptions = const <String>[],
	}) async {
	final Directory outputDir = fs.directory(outputPath);
	outputDir.createSync(recursive: true);

	printTrace('Compiling Dart to kernel: $mainPath');
	final List<String> entryPointsJsonFiles = <String>[
	artifacts.getArtifactPath(Artifact.entryPointsJson, platform, buildMode),
	artifacts.getArtifactPath(Artifact.entryPointsExtraJson, platform, buildMode),
	];

	if ((extraFrontEndOptions != null) && extraFrontEndOptions.isNotEmpty)
	printTrace('Extra front-end options: $extraFrontEndOptions');

	final String depfilePath = fs.path.join(outputPath, 'kernel_compile.d');
	final CompilerOutput compilerOutput = await kernelCompiler.compile(
	sdkRoot: artifacts.getArtifactPath(Artifact.flutterPatchedSdkPath),
	mainPath: mainPath,
	outputFilePath: fs.path.join(outputPath, 'app.dill'),
	depFilePath: depfilePath,
	extraFrontEndOptions: extraFrontEndOptions,
	linkPlatformKernelIn: true,
	aot: true,
	entryPointsJsonFiles: entryPointsJsonFiles,
	trackWidgetCreation: false,
	targetProductVm: buildMode == BuildMode.release,
	);

	// Write path to frontend_server, since things need to be re-generated when that changes.
	final String frontendPath = artifacts.getArtifactPath(Artifact.frontendServerSnapshotForEngineDartSdk);
	await fs.directory(outputPath).childFile('frontend_server.d').writeAsString('frontend_server.d: $frontendPath\n');

	return compilerOutput?.outputFilename;
	}

	bool _isValidAotPlatform(TargetPlatform platform, BuildMode buildMode) {
	if (buildMode == BuildMode.debug)
	return false;
	return const <TargetPlatform>[
	TargetPlatform.android_arm,
	TargetPlatform.android_arm64,
	TargetPlatform.ios,
	].contains(platform);
	}

	String _getPackagePath(PackageMap packageMap, String package) {
	return fs.path.dirname(fs.path.fromUri(packageMap.map[package]));
	}
	}

	class CoreJITSnapshotter {
	/// Builds a "Core JIT" VM snapshot of the specified kernel. This snapshot
	/// includes data as well as either machine code or DBC, depending on build
	/// configuration.
	Future<int> build({
	@required TargetPlatform platform,
	@required BuildMode buildMode,
	@required String mainPath,
	@required String packagesPath,
	@required String outputPath,
	@required String compilationTraceFilePath,
	List<String> extraGenSnapshotOptions = const <String>[],
	}) async {
	if (!_isValidCoreJitPlatform(platform)) {
	printError('${getNameForTargetPlatform(platform)} does not support Core JIT compilation.');
	return 1;
	}

	final Directory outputDir = fs.directory(outputPath);
	outputDir.createSync(recursive: true);

	final List<String> inputPaths = <String>[mainPath, compilationTraceFilePath];
	final Set<String> outputPaths = new Set<String>();

	final String depfilePath = fs.path.join(outputDir.path, 'snapshot.d');
	final List<String> genSnapshotArgs = <String>[
	'--reify-generic-functions',
	'--strong',
	'--sync-async',
	];
	if (buildMode == BuildMode.debug) {
	genSnapshotArgs.add('--enable_asserts');
	}
	if (extraGenSnapshotOptions != null && extraGenSnapshotOptions.isNotEmpty) {
	printTrace('Extra gen_snapshot options: $extraGenSnapshotOptions');
	genSnapshotArgs.addAll(extraGenSnapshotOptions);
	}

	// Blob Core JIT snapshot.
	final String vmSnapshotData = fs.path.join(outputDir.path, 'vm_snapshot_data');
	final String isolateSnapshotData = fs.path.join(outputDir.path, 'isolate_snapshot_data');
	final String vmSnapshotInstructions = fs.path.join(outputDir.path, 'vm_snapshot_instr');
	final String isolateSnapshotInstructions = fs.path.join(outputDir.path, 'isolate_snapshot_instr');
	outputPaths.addAll(<String>[vmSnapshotData, isolateSnapshotData, vmSnapshotInstructions, isolateSnapshotInstructions]);
	genSnapshotArgs.addAll(<String>[
	'--snapshot_kind=core-jit',
	'--vm_snapshot_data=$vmSnapshotData',
	'--isolate_snapshot_data=$isolateSnapshotData',
	'--vm_snapshot_instructions=$vmSnapshotInstructions',
	'--isolate_snapshot_instructions=$isolateSnapshotInstructions',
	'--load_compilation_trace=$compilationTraceFilePath',
	]);

	if (platform == TargetPlatform.android_arm) {
	// Use softfp for Android armv7 devices.
	// TODO(cbracken): eliminate this when we fix https://github.com/flutter/flutter/issues/17489
	genSnapshotArgs.add('--no-sim-use-hardfp');

	// Not supported by the Pixel in 32-bit mode.
	genSnapshotArgs.add('--no-use-integer-division');
	}

	genSnapshotArgs.add(mainPath);

	// Verify that all required inputs exist.
	final Iterable<String> missingInputs = inputPaths.where((String p) => !fs.isFileSync(p));
	if (missingInputs.isNotEmpty) {
	printError('Missing input files: $missingInputs from $inputPaths');
	return 1;
	}

	// If inputs and outputs have not changed since last run, skip the build.
	final Fingerprinter fingerprinter = new Fingerprinter(
	fingerprintPath: '$depfilePath.fingerprint',
	paths: <String>[mainPath]..addAll(inputPaths)..addAll(outputPaths),
	properties: <String, String>{
	'buildMode': buildMode.toString(),
	'targetPlatform': platform.toString(),
	'entryPoint': mainPath,
	'extraGenSnapshotOptions': extraGenSnapshotOptions.join(' '),
	},
	depfilePaths: <String>[],
	);
	if (await fingerprinter.doesFingerprintMatch()) {
	printTrace('Skipping Core JIT snapshot build. Fingerprint match.');
	return 0;
	}

	final SnapshotType snapshotType = new SnapshotType(platform, buildMode);
	final int genSnapshotExitCode = await genSnapshot.run(
	snapshotType: snapshotType,
	packagesPath: packagesPath,
	additionalArgs: genSnapshotArgs,
	);
	if (genSnapshotExitCode != 0) {
	printError('Dart snapshot generator failed with exit code $genSnapshotExitCode');
	return genSnapshotExitCode;
	}

	// Write path to gen_snapshot, since snapshots have to be re-generated when we roll
	// the Dart SDK.
	final String genSnapshotPath = GenSnapshot.getSnapshotterPath(snapshotType);
	await outputDir.childFile('gen_snapshot.d').writeAsString('gen_snapshot.d: $genSnapshotPath\n');

	// Compute and record build fingerprint.
	await fingerprinter.writeFingerprint();
	return 0;
	}

	bool _isValidCoreJitPlatform(TargetPlatform platform) {
	return const <TargetPlatform>[
	TargetPlatform.android_arm,
	TargetPlatform.android_arm64,
	].contains(platform);
	}
	}