runtime/tools/dartfuzz/dartfuzz_test.dart - sdk.git - Git at Google

 // Copyright (c) 2018, 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.

 // @dart = 2.9

 import 'dart:io';
 import 'dart:isolate';
 import 'dart:math';

 import 'package:args/args.dart';

 import 'dartfuzz.dart';

 const debug = false;
 const sigkill = 9;
 const timeout = 60; // in seconds
 const dartHeapSize = 128; // in Mb

 // Status of divergence report.
 enum ReportStatus { reported, ignored, rerun, no_divergence }

 /// Result of running a test.
 class TestResult {
   const TestResult(this.output, this.stderr, this.exitCode);
   final String output;
   final String stderr;
   final int exitCode;
 }

 /// Command runner.
 TestResult runCommand(List<String> cmd, Map<String, String> env) {
   ProcessResult res = Process.runSync(
       'timeout', ['-s', '$sigkill', '$timeout', ...cmd],
       environment: env);
   if (debug) {
     print('\nrunning $cmd yields:\n'
         '${res.exitCode}\n${res.stdout}\n${res.stderr}\n');
   }
   return TestResult(res.stdout, res.stderr, res.exitCode);
 }

 /// Abstraction for running one test in a particular mode.
 abstract class TestRunner {
   TestResult run();
   String description;

   // Factory.
   static TestRunner getTestRunner(String mode, String top, String tmp,
       Map<String, String> env, String fileName, Random rand) {
     String prefix = mode.substring(0, 3).toUpperCase();
     String tag = getTag(mode);
     List<String> extraFlags = [];
     // Every once in a while, stress test JIT.
     if (mode.startsWith('jit') && rand.nextInt(4) == 0) {
       final r = rand.nextInt(7);
       if (r == 0) {
         prefix += '-NOFIELDGUARDS';
         extraFlags += ['--use_field_guards=false'];
       } else if (r == 1) {
         prefix += '-NOINTRINSIFY';
         extraFlags += ['--intrinsify=false'];
       } else if (r == 2) {
         final freq = rand.nextInt(1000) + 500;
         prefix += '-COMPACTEVERY-${freq}';
         extraFlags += ['--gc_every=${freq}', '--use_compactor=true'];
       } else if (r == 3) {
         final freq = rand.nextInt(1000) + 500;
         prefix += '-MARKSWEEPEVERY-${freq}';
         extraFlags += ['--gc_every=${freq}', '--use_compactor=false'];
       } else if (r == 4) {
         final freq = rand.nextInt(100) + 50;
         prefix += '-DEPOPTEVERY-${freq}';
         extraFlags += ['--deoptimize_every=${freq}'];
       } else if (r == 5) {
         final freq = rand.nextInt(100) + 50;
         prefix += '-STACKTRACEEVERY-${freq}';
         extraFlags += ['--stacktrace_every=${freq}'];
       } else if (r == 6) {
         prefix += '-OPTCOUNTER';
         extraFlags += ['--optimization_counter_threshold=1'];
       }
     }
     // Every once in a while, disable VFP on arm32.
     if (mode.contains('arm32') && rand.nextInt(4) == 0) {
       prefix += '-noVFP';
       extraFlags += ['--no-use-vfp'];
     }
     // Every once in a while, use -O3 compiler.
     if (!mode.startsWith('djs') && rand.nextInt(4) == 0) {
       prefix += '-O3';
       extraFlags += ['--optimization_level=3'];
     }
     // Every once in a while, use the slowpath flag.
     if (!mode.startsWith('djs') && rand.nextInt(4) == 0) {
       prefix += '-SLOWPATH';
       extraFlags += ['--use-slow-path'];
     }
     // Every once in a while, use the deterministic flag.
     if (!mode.startsWith('djs') && rand.nextInt(4) == 0) {
       prefix += '-DET';
       extraFlags += ['--deterministic'];
     }
     // Construct runner.
     if (mode.startsWith('jit')) {
       return TestRunnerJIT(prefix, tag, top, tmp, env, fileName, extraFlags);
     } else if (mode.startsWith('aot')) {
       return TestRunnerAOT(prefix, tag, top, tmp, env, fileName, extraFlags);
     } else if (mode.startsWith('djs')) {
       return TestRunnerDJS(prefix, tag, top, tmp, env, fileName);
     }
     throw ('unknown runner in mode: $mode');
   }

   // Convert mode to tag.
   static String getTag(String mode) {
     if (mode.endsWith('debug-ia32')) return 'DebugIA32';
     if (mode.endsWith('debug-x64')) return 'DebugX64';
     if (mode.endsWith('debug-arm32')) return 'DebugSIMARM';
     if (mode.endsWith('debug-arm64')) return 'DebugSIMARM64';
     if (mode.endsWith('ia32')) return 'ReleaseIA32';
     if (mode.endsWith('x64')) return 'ReleaseX64';
     if (mode.endsWith('arm32')) return 'ReleaseSIMARM';
     if (mode.endsWith('arm64')) return 'ReleaseSIMARM64';
     throw ('unknown tag in mode: $mode');
   }

   // Print steps to reproduce build and run.
   void printReproductionCommand();
 }

 /// Concrete test runner of Dart JIT.
 class TestRunnerJIT implements TestRunner {
   TestRunnerJIT(String prefix, String tag, this.top, String tmp, this.env,
       this.fileName, List<String> extraFlags) {
     description = '$prefix-$tag';
     dart = '$top/out/$tag/dart';
     cmd = [
       dart,
       ...extraFlags,
       '--old_gen_heap_size=${dartHeapSize}',
       fileName
     ];
   }

   TestResult run() {
     return runCommand(cmd, env);
   }

   void printReproductionCommand() =>
       print(cmd.join(" ").replaceAll('$top/', ''));

   String description;
   String dart;
   String fileName;
   final String top;
   Map<String, String> env;
   List<String> cmd;
 }

 /// Concrete test runner of Dart AOT.
 class TestRunnerAOT implements TestRunner {
   TestRunnerAOT(String prefix, String tag, this.top, this.tmp,
       Map<String, String> e, this.fileName, List<String> extraFlags) {
     description = '$prefix-$tag';
     precompiler = '$top/pkg/vm/tool/precompiler2';
     dart = '$top/pkg/vm/tool/dart_precompiled_runtime2';
     snapshot = '$tmp/snapshot';
     env = Map<String, String>.from(e);
     env['DART_CONFIGURATION'] = tag;
     env['DART_VM_FLAGS'] = '--enable-asserts';
     cmd = [precompiler, ...extraFlags, fileName, snapshot];
   }

   TestResult run() {
     TestResult result = runCommand(cmd, env);
     if (result.exitCode != 0) {
       return result;
     }
     return runCommand(
         [dart, '--old_gen_heap_size=${dartHeapSize}', snapshot], env);
   }

   void printReproductionCommand() {
     print([
       "DART_CONFIGURATION='${env['DART_CONFIGURATION']}'",
       "DART_VM_FLAGS='${env['DART_VM_FLAGS']}'",
       ...cmd
     ].join(" ").replaceAll('$top/', '').replaceAll('$tmp/', ''));
     print([dart, snapshot]
         .join(" ")
         .replaceAll('$top/', '')
         .replaceAll('$tmp/', ''));
   }

   String description;
   String precompiler;
   String dart;
   String fileName;
   String snapshot;
   final String top;
   final String tmp;
   Map<String, String> env;
   List<String> cmd;
 }

 /// Concrete test runner of Dart2JS.
 class TestRunnerDJS implements TestRunner {
   TestRunnerDJS(
       String prefix, String tag, this.top, this.tmp, this.env, this.fileName) {
     description = '$prefix-$tag';
     dart2js = '$top/sdk/bin/dart2js';
     js = '$tmp/out.js';
   }

   TestResult run() {
     TestResult result = runCommand([dart2js, fileName, '-o', js], env);
     if (result.exitCode != 0) {
       return result;
     }
     return runCommand(['nodejs', js], env);
   }

   void printReproductionCommand() {
     print([dart2js, fileName, '-o', js]
         .join(" ")
         .replaceAll('$top/', '')
         .replaceAll('$tmp/', ''));
     print('nodejs out.js');
   }

   String description;
   String dart2js;
   String fileName;
   String js;
   final String top;
   final String tmp;
   Map<String, String> env;
 }

 /// Class to run fuzz testing.
 class DartFuzzTest {
   DartFuzzTest(
       this.env,
       this.repeat,
       this.time,
       this.numOutputLines,
       this.trueDivergence,
       this.showStats,
       this.top,
       this.mode1,
       this.mode2,
       this.rerun,
       this.dartSdkRevision);

   int run() {
     setup();

     print('\n${isolate}: start');
     if (showStats) {
       showStatistics();
     }

     for (int i = 0; i < repeat; i++) {
       numTests++;
       seed = rand.nextInt(1 << 32);
       generateTest();
       runTest();
       if (showStats) {
         showStatistics();
       }
       // Timeout?
       if (timeIsUp()) {
         break;
       }
     }

     print('\n${isolate}: done');
     showStatistics();
     print('');
     if (timeoutSeeds.isNotEmpty) {
       print('\n${isolate} timeout: ' + timeoutSeeds.join(", "));
       print('');
     }
     if (skippedSeeds.isNotEmpty) {
       print('\n${isolate} skipped: ' + skippedSeeds.join(", "));
       print('');
     }

     cleanup();
     return numDivergences;
   }

   void setup() {
     rand = Random();
     tmpDir = Directory.systemTemp.createTempSync('dart_fuzz');
     fileName = '${tmpDir.path}/fuzz.dart';

     // Testcase generation flags.

     // Only use FP when modes have the same architecture (to avoid false
     // divergences between 32-bit and 64-bit versions).
     fp = sameArchitecture(mode1, mode2);
     // Occasionally test FFI (if capable).
     ffi = ffiCapable(mode1, mode2) && (rand.nextInt(5) == 0);
     // Resort to flat types for the more expensive modes.
     flatTp = !nestedTypesAllowed(mode1, mode2);

     runner1 =
         TestRunner.getTestRunner(mode1, top, tmpDir.path, env, fileName, rand);
     runner2 =
         TestRunner.getTestRunner(mode2, top, tmpDir.path, env, fileName, rand);
     isolate =
         'Isolate (${tmpDir.path}) ${fp ? "" : "NO-"}FP ${ffi ? "" : "NO-"}FFI ${flatTp ? "" : "NO-"}FLAT : '
         '${runner1.description} - ${runner2.description}';

     start_time = DateTime.now().millisecondsSinceEpoch;
     current_time = start_time;
     report_time = start_time;
     end_time = start_time + max(0, time - timeout) * 1000;

     numTests = 0;
     numSuccess = 0;
     numSkipped = 0;
     numRerun = 0;
     numTimeout = 0;
     numDivergences = 0;
     timeoutSeeds = {};
     skippedSeeds = {};
   }

   bool sameArchitecture(String mode1, String mode2) =>
       ((mode1.contains('arm32') && mode2.contains('arm32')) ||
           (mode1.contains('arm64') && mode2.contains('arm64')) ||
           (mode1.contains('x64') && mode2.contains('x64')) ||
           (mode1.contains('ia32') && mode2.contains('ia32')));

   bool ffiCapable(String mode1, String mode2) =>
       mode1.startsWith('jit') &&
       mode2.startsWith('jit') &&
       (!mode1.contains('arm') && !mode2.contains('arm'));

   bool nestedTypesAllowed(String mode1, String mode2) =>
       (!mode1.contains('arm') && !mode2.contains('arm'));

   bool timeIsUp() {
     if (time > 0) {
       current_time = DateTime.now().millisecondsSinceEpoch;
       if (current_time > end_time) {
         return true;
       }
       // Report every 10 minutes.
       if ((current_time - report_time) > (10 * 60 * 1000)) {
         print(
             '\n${isolate}: busy @${numTests} ${current_time - start_time} seconds....');
         report_time = current_time;
       }
     }
     return false;
   }

   void cleanup() {
     tmpDir.delete(recursive: true);
   }

   void showStatistics() {
     stdout.write('\rTests: $numTests Success: $numSuccess (Rerun: $numRerun) '
         'Skipped: $numSkipped Timeout: $numTimeout '
         'Divergences: $numDivergences');
   }

   void generateTest() {
     final file = File(fileName).openSync(mode: FileMode.write);
     DartFuzz(seed, fp, ffi, flatTp, file).run();
     file.closeSync();
   }

   void runTest() {
     TestResult result1 = runner1.run();
     TestResult result2 = runner2.run();
     var report = checkDivergence(result1, result2);
     if (report == ReportStatus.rerun && rerun) {
       print("\nCommencing re-run .... \n");
       numDivergences--;
       result1 = runner1.run();
       result2 = runner2.run();
       report = checkDivergence(result1, result2);
       if (report == ReportStatus.no_divergence) {
         print("\nNo error on re-run\n");
         numRerun++;
       }
     }
     if (report == ReportStatus.reported ||
         (!rerun && report == ReportStatus.rerun)) {
       showReproduce();
     }
   }

   ReportStatus checkDivergence(TestResult result1, TestResult result2) {
     if (result1.exitCode == result2.exitCode) {
       // No divergence in result code.
       switch (result1.exitCode) {
         case 0:
           // Both were successful, inspect output.
           if (result1.output == result2.output) {
             numSuccess++;
           } else {
             reportDivergence(result1, result2);
             return ReportStatus.reported;
           }
           break;
         case -sigkill:
           // Both had a time out.
           numTimeout++;
           timeoutSeeds.add(seed);
           break;
         default:
           // Both had an error.
           numSkipped++;
           skippedSeeds.add(seed);
           break;
       }
     } else {
       // Divergence in result code.
       if (trueDivergence) {
         // When only true divergences are requested, any divergence
         // with at least one time out or out of memory error is
         // treated as a regular time out or skipped test, respectively.
         if (result1.exitCode == -sigkill || result2.exitCode == -sigkill) {
           numTimeout++;
           timeoutSeeds.add(seed);
           return ReportStatus.ignored;
         } else if (result1.exitCode == DartFuzz.oomExitCode ||
             result2.exitCode == DartFuzz.oomExitCode) {
           numSkipped++;
           skippedSeeds.add(seed);
           return ReportStatus.ignored;
         }
       }
       reportDivergence(result1, result2);
       // Exit codes outside [-255,255] are not due to Dart VM exits.
       if (result1.exitCode.abs() > 255 || result2.exitCode.abs() > 255) {
         return ReportStatus.rerun;
       } else {
         return ReportStatus.reported;
       }
     }
     return ReportStatus.no_divergence;
   }

   String generateReport(TestResult result1, TestResult result2) {
     if (result1.exitCode == result2.exitCode) {
       return "output";
     } else {
       return "${result1.exitCode} vs ${result2.exitCode}";
     }
   }

   void printDivergenceOutput(String string, int numLines) {
     final lines = string.split('\n');
     print(lines.sublist(0, min(lines.length, numLines)).join('\n'));
   }

   void reportDivergence(TestResult result1, TestResult result2) {
     numDivergences++;
     String report = generateReport(result1, result2);
     print('\n${isolate}: !DIVERGENCE! $version:$seed (${report})');
     if (result1.exitCode == result2.exitCode) {
       if (numOutputLines > 0) {
         // Only report the actual output divergence details up to
         // numOutputLines, since this output may be lengthy and should be
         // reproducable anyway.
         print('\nout1:\n');
         printDivergenceOutput(result1.output, numOutputLines);
         print('\nout2:\n');
         printDivergenceOutput(result2.output, numOutputLines);
       }
     } else {
       // For any other divergence, always report what went wrong.
       if (result1.exitCode != 0) {
         print(
             '\nfail1:\n${result1.exitCode}\n${result1.output}\n${result1.stderr}\n');
       }
       if (result2.exitCode != 0) {
         print(
             '\nfail2:\n${result2.exitCode}\n${result2.output}\n${result2.stderr}\n');
       }
     }
   }

   void showReproduce() {
     print("\n-- BEGIN REPRODUCE  --\n");
     print("DART SDK REVISION: $dartSdkRevision\n");
     print(
         "dart runtime/tools/dartfuzz/dartfuzz.dart --${fp ? "" : "no-"}fp --${ffi ? "" : "no-"}ffi "
         "--${flatTp ? "" : "no-"}flat "
         "--seed ${seed} fuzz.dart");
     print("\n-- RUN 1 --\n");
     runner1.printReproductionCommand();
     print("\n-- RUN 2 --\n");
     runner2.printReproductionCommand();
     print("\n-- END REPRODUCE  --\n");
   }

   // Context.
   final Map<String, String> env;
   final int repeat;
   final int time;
   final int numOutputLines;
   final bool trueDivergence;
   final bool showStats;
   final String top;
   final String mode1;
   final String mode2;
   final bool rerun;
   final String dartSdkRevision;

   // Test.
   Random rand;
   Directory tmpDir;
   String fileName;
   TestRunner runner1;
   TestRunner runner2;
   bool fp;
   bool ffi;
   bool flatTp;
   String isolate;
   int seed;

   // Timing
   int start_time;
   int current_time;
   int report_time;
   int end_time;

   // Stats.
   int numTests;
   int numSuccess;
   int numSkipped;
   int numRerun;
   int numTimeout;
   int numDivergences;
   Set<int> timeoutSeeds;
   Set<int> skippedSeeds;
 }

 /// Class to start fuzz testing session.
 class DartFuzzTestSession {
   DartFuzzTestSession(
       this.isolates,
       this.repeat,
       this.time,
       this.numOutputLines,
       this.trueDivergence,
       this.showStats,
       String tp,
       this.mode1,
       this.mode2,
       this.rerun)
       : top = getTop(tp),
         dartSdkRevision = getDartSdkRevision(tp);

   start() async {
     print('\n**\n**** Dart Fuzz Testing Session\n**\n');
     print('Fuzz Version      : ${version}');
     print('Dart SDK Revision : ${dartSdkRevision}');
     print('Isolates          : ${isolates}');
     print('Tests             : ${repeat}');
     if (time > 0) {
       print('Time              : ${time} seconds');
     } else {
       print('Time              : unlimited');
     }
     print('True Divergence   : ${trueDivergence}');
     print('Show Stats        : ${showStats}');
     print('Dart Dev          : ${top}');
     // Fork.
     List<ReceivePort> ports = List();
     for (int i = 0; i < isolates; i++) {
       ReceivePort r = ReceivePort();
       ports.add(r);
       port = r.sendPort;
       await Isolate.spawn(run, this);
     }
     // Join.
     int divergences = 0;
     for (int i = 0; i < isolates; i++) {
       var d = await ports[i].first;
       divergences += d;
     }
     if (divergences == 0) {
       print('\nsuccess\n');
     } else {
       print('\nfailure ($divergences divergences)\n');
       exitCode = 1;
     }
   }

   static run(DartFuzzTestSession session) {
     int divergences = 0;
     try {
       final m1 = getMode(session.mode1, null);
       final m2 = getMode(session.mode2, m1);
       final fuzz = DartFuzzTest(
           Platform.environment,
           session.repeat,
           session.time,
           session.numOutputLines,
           session.trueDivergence,
           session.showStats,
           session.top,
           m1,
           m2,
           session.rerun,
           session.dartSdkRevision);
       divergences = fuzz.run();
     } catch (e) {
       print('Isolate: $e');
     }
     session.port.send(divergences);
   }

   // Picks a top directory (command line, environment, or current).
   static String getTop(String top) {
     if (top == null || top == '') {
       top = Platform.environment['DART_TOP'];
     }
     if (top == null || top == '') {
       top = Directory.current.path;
     }
     return top;
   }

   static String getDartSdkRevision(String top) {
     ProcessResult res =
         Process.runSync(Platform.resolvedExecutable, ['--version']);
     return res.stderr;
   }

   // Picks a mode (command line or random).
   static String getMode(String mode, String other) {
     // Random when not set.
     if (mode == null || mode == '') {
       // Pick a mode at random (cluster), different from other.
       Random rand = Random();
       do {
         mode = clusterModes[rand.nextInt(clusterModes.length)];
       } while (mode == other);
     }
     // Verify mode.
     if (modes.contains(mode)) {
       return mode;
     }
     throw ('unknown mode: $mode');
   }

   // Context.
   final int isolates;
   final int repeat;
   final int time;
   final int numOutputLines;
   final bool trueDivergence;
   final bool showStats;
   final bool rerun;
   final String top;
   final String mode1;
   final String mode2;
   final String dartSdkRevision;

   // Passes each port to isolate.
   SendPort port;

   // Modes used on cluster runs.
   static const List<String> clusterModes = [
     'jit-debug-ia32',
     'jit-debug-x64',
     'jit-debug-arm32',
     'jit-debug-arm64',
     'jit-ia32',
     'jit-x64',
     'jit-arm32',
     'jit-arm64',
     'aot-debug-x64',
     'aot-x64',
   ];

   // Modes not used on cluster runs because they have outstanding issues.
   static const List<String> nonClusterModes = [
     // Times out often:
     'aot-debug-arm32',
     'aot-debug-arm64',
     'aot-arm32',
     'aot-arm64',
     // Too many divergences (due to arithmetic):
     'js-x64',
   ];

   // All modes.
   static List<String> modes = clusterModes + nonClusterModes;
 }

 /// Main driver for a fuzz testing session.
 main(List<String> arguments) {
   // Set up argument parser.
   final parser = ArgParser()
     ..addOption('isolates', help: 'number of isolates to use', defaultsTo: '1')
     ..addOption('repeat', help: 'number of tests to run', defaultsTo: '1000')
     ..addOption('time', help: 'time limit in seconds', defaultsTo: '0')
     ..addOption('num-output-lines',
         help:
             'number of output lines to be printed in the case of a divergence',
         defaultsTo: '200')
     ..addFlag('true-divergence',
         negatable: true, help: 'only report true divergences', defaultsTo: true)
     ..addFlag('show-stats',
         negatable: true, help: 'show session statistics', defaultsTo: true)
     ..addOption('dart-top', help: 'explicit value for \$DART_TOP')
     ..addOption('mode1', help: 'execution mode 1')
     ..addOption('mode2', help: 'execution mode 2')
     ..addFlag('rerun',
         negatable: true,
         help: 're-run if test only diverges on return code (not in the output)',
         defaultsTo: true)
     // Undocumented options for cluster runs.
     ..addOption('shards',
         help: 'number of shards used in cluster run', defaultsTo: '1')
     ..addOption('shard', help: 'shard id in cluster run', defaultsTo: '1')
     ..addOption('output_directory',
         help: 'path to output (ignored)', defaultsTo: null)
     ..addOption('output-directory',
         help: 'path to output (ignored)', defaultsTo: null);

   // Starts fuzz testing session.
   try {
     final results = parser.parse(arguments);
     final shards = int.parse(results['shards']);
     final shard = int.parse(results['shard']);
     if (shards > 1) {
       print('\nSHARD $shard OF $shards');
     }
     DartFuzzTestSession(
             int.parse(results['isolates']),
             int.parse(results['repeat']),
             int.parse(results['time']),
             int.parse(results['num-output-lines']),
             results['true-divergence'],
             results['show-stats'],
             results['dart-top'],
             results['mode1'],
             results['mode2'],
             results['rerun'])
         .start();
   } catch (e) {
     print('Usage: dart dartfuzz_test.dart [OPTIONS]\n${parser.usage}\n$e');
     exitCode = 255;
   }
 }
	// Copyright (c) 2018, 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.

	// @dart = 2.9

	import 'dart:io';
	import 'dart:isolate';
	import 'dart:math';

	import 'package:args/args.dart';

	import 'dartfuzz.dart';

	const debug = false;
	const sigkill = 9;
	const timeout = 60; // in seconds
	const dartHeapSize = 128; // in Mb

	// Status of divergence report.
	enum ReportStatus { reported, ignored, rerun, no_divergence }

	/// Result of running a test.
	class TestResult {
	const TestResult(this.output, this.stderr, this.exitCode);
	final String output;
	final String stderr;
	final int exitCode;
	}

	/// Command runner.
	TestResult runCommand(List<String> cmd, Map<String, String> env) {
	ProcessResult res = Process.runSync(
	'timeout', ['-s', '$sigkill', '$timeout', ...cmd],
	environment: env);
	if (debug) {
	print('\nrunning $cmd yields:\n'
	'${res.exitCode}\n${res.stdout}\n${res.stderr}\n');
	}
	return TestResult(res.stdout, res.stderr, res.exitCode);
	}

	/// Abstraction for running one test in a particular mode.
	abstract class TestRunner {
	TestResult run();
	String description;

	// Factory.
	static TestRunner getTestRunner(String mode, String top, String tmp,
	Map<String, String> env, String fileName, Random rand) {
	String prefix = mode.substring(0, 3).toUpperCase();
	String tag = getTag(mode);
	List<String> extraFlags = [];
	// Every once in a while, stress test JIT.
	if (mode.startsWith('jit') && rand.nextInt(4) == 0) {
	final r = rand.nextInt(7);
	if (r == 0) {
	prefix += '-NOFIELDGUARDS';
	extraFlags += ['--use_field_guards=false'];
	} else if (r == 1) {
	prefix += '-NOINTRINSIFY';
	extraFlags += ['--intrinsify=false'];
	} else if (r == 2) {
	final freq = rand.nextInt(1000) + 500;
	prefix += '-COMPACTEVERY-${freq}';
	extraFlags += ['--gc_every=${freq}', '--use_compactor=true'];
	} else if (r == 3) {
	final freq = rand.nextInt(1000) + 500;
	prefix += '-MARKSWEEPEVERY-${freq}';
	extraFlags += ['--gc_every=${freq}', '--use_compactor=false'];
	} else if (r == 4) {
	final freq = rand.nextInt(100) + 50;
	prefix += '-DEPOPTEVERY-${freq}';
	extraFlags += ['--deoptimize_every=${freq}'];
	} else if (r == 5) {
	final freq = rand.nextInt(100) + 50;
	prefix += '-STACKTRACEEVERY-${freq}';
	extraFlags += ['--stacktrace_every=${freq}'];
	} else if (r == 6) {
	prefix += '-OPTCOUNTER';
	extraFlags += ['--optimization_counter_threshold=1'];
	}
	}
	// Every once in a while, disable VFP on arm32.
	if (mode.contains('arm32') && rand.nextInt(4) == 0) {
	prefix += '-noVFP';
	extraFlags += ['--no-use-vfp'];
	}
	// Every once in a while, use -O3 compiler.
	if (!mode.startsWith('djs') && rand.nextInt(4) == 0) {
	prefix += '-O3';
	extraFlags += ['--optimization_level=3'];
	}
	// Every once in a while, use the slowpath flag.
	if (!mode.startsWith('djs') && rand.nextInt(4) == 0) {
	prefix += '-SLOWPATH';
	extraFlags += ['--use-slow-path'];
	}
	// Every once in a while, use the deterministic flag.
	if (!mode.startsWith('djs') && rand.nextInt(4) == 0) {
	prefix += '-DET';
	extraFlags += ['--deterministic'];
	}
	// Construct runner.
	if (mode.startsWith('jit')) {
	return TestRunnerJIT(prefix, tag, top, tmp, env, fileName, extraFlags);
	} else if (mode.startsWith('aot')) {
	return TestRunnerAOT(prefix, tag, top, tmp, env, fileName, extraFlags);
	} else if (mode.startsWith('djs')) {
	return TestRunnerDJS(prefix, tag, top, tmp, env, fileName);
	}
	throw ('unknown runner in mode: $mode');
	}

	// Convert mode to tag.
	static String getTag(String mode) {
	if (mode.endsWith('debug-ia32')) return 'DebugIA32';
	if (mode.endsWith('debug-x64')) return 'DebugX64';
	if (mode.endsWith('debug-arm32')) return 'DebugSIMARM';
	if (mode.endsWith('debug-arm64')) return 'DebugSIMARM64';
	if (mode.endsWith('ia32')) return 'ReleaseIA32';
	if (mode.endsWith('x64')) return 'ReleaseX64';
	if (mode.endsWith('arm32')) return 'ReleaseSIMARM';
	if (mode.endsWith('arm64')) return 'ReleaseSIMARM64';
	throw ('unknown tag in mode: $mode');
	}

	// Print steps to reproduce build and run.
	void printReproductionCommand();
	}

	/// Concrete test runner of Dart JIT.
	class TestRunnerJIT implements TestRunner {
	TestRunnerJIT(String prefix, String tag, this.top, String tmp, this.env,
	this.fileName, List<String> extraFlags) {
	description = '$prefix-$tag';
	dart = '$top/out/$tag/dart';
	cmd = [
	dart,
	...extraFlags,
	'--old_gen_heap_size=${dartHeapSize}',
	fileName
	];
	}

	TestResult run() {
	return runCommand(cmd, env);
	}

	void printReproductionCommand() =>
	print(cmd.join(" ").replaceAll('$top/', ''));

	String description;
	String dart;
	String fileName;
	final String top;
	Map<String, String> env;
	List<String> cmd;
	}

	/// Concrete test runner of Dart AOT.
	class TestRunnerAOT implements TestRunner {
	TestRunnerAOT(String prefix, String tag, this.top, this.tmp,
	Map<String, String> e, this.fileName, List<String> extraFlags) {
	description = '$prefix-$tag';
	precompiler = '$top/pkg/vm/tool/precompiler2';
	dart = '$top/pkg/vm/tool/dart_precompiled_runtime2';
	snapshot = '$tmp/snapshot';
	env = Map<String, String>.from(e);
	env['DART_CONFIGURATION'] = tag;
	env['DART_VM_FLAGS'] = '--enable-asserts';
	cmd = [precompiler, ...extraFlags, fileName, snapshot];
	}

	TestResult run() {
	TestResult result = runCommand(cmd, env);
	if (result.exitCode != 0) {
	return result;
	}
	return runCommand(
	[dart, '--old_gen_heap_size=${dartHeapSize}', snapshot], env);
	}

	void printReproductionCommand() {
	print([
	"DART_CONFIGURATION='${env['DART_CONFIGURATION']}'",
	"DART_VM_FLAGS='${env['DART_VM_FLAGS']}'",
	...cmd
	].join(" ").replaceAll('$top/', '').replaceAll('$tmp/', ''));
	print([dart, snapshot]
	.join(" ")
	.replaceAll('$top/', '')
	.replaceAll('$tmp/', ''));
	}

	String description;
	String precompiler;
	String dart;
	String fileName;
	String snapshot;
	final String top;
	final String tmp;
	Map<String, String> env;
	List<String> cmd;
	}

	/// Concrete test runner of Dart2JS.
	class TestRunnerDJS implements TestRunner {
	TestRunnerDJS(
	String prefix, String tag, this.top, this.tmp, this.env, this.fileName) {
	description = '$prefix-$tag';
	dart2js = '$top/sdk/bin/dart2js';
	js = '$tmp/out.js';
	}

	TestResult run() {
	TestResult result = runCommand([dart2js, fileName, '-o', js], env);
	if (result.exitCode != 0) {
	return result;
	}
	return runCommand(['nodejs', js], env);
	}

	void printReproductionCommand() {
	print([dart2js, fileName, '-o', js]
	.join(" ")
	.replaceAll('$top/', '')
	.replaceAll('$tmp/', ''));
	print('nodejs out.js');
	}

	String description;
	String dart2js;
	String fileName;
	String js;
	final String top;
	final String tmp;
	Map<String, String> env;
	}

	/// Class to run fuzz testing.
	class DartFuzzTest {
	DartFuzzTest(
	this.env,
	this.repeat,
	this.time,
	this.numOutputLines,
	this.trueDivergence,
	this.showStats,
	this.top,
	this.mode1,
	this.mode2,
	this.rerun,
	this.dartSdkRevision);

	int run() {
	setup();

	print('\n${isolate}: start');
	if (showStats) {
	showStatistics();
	}

	for (int i = 0; i < repeat; i++) {
	numTests++;
	seed = rand.nextInt(1 << 32);
	generateTest();
	runTest();
	if (showStats) {
	showStatistics();
	}
	// Timeout?
	if (timeIsUp()) {
	break;
	}
	}

	print('\n${isolate}: done');
	showStatistics();
	print('');
	if (timeoutSeeds.isNotEmpty) {
	print('\n${isolate} timeout: ' + timeoutSeeds.join(", "));
	print('');
	}
	if (skippedSeeds.isNotEmpty) {
	print('\n${isolate} skipped: ' + skippedSeeds.join(", "));
	print('');
	}

	cleanup();
	return numDivergences;
	}

	void setup() {
	rand = Random();
	tmpDir = Directory.systemTemp.createTempSync('dart_fuzz');
	fileName = '${tmpDir.path}/fuzz.dart';

	// Testcase generation flags.

	// Only use FP when modes have the same architecture (to avoid false
	// divergences between 32-bit and 64-bit versions).
	fp = sameArchitecture(mode1, mode2);
	// Occasionally test FFI (if capable).
	ffi = ffiCapable(mode1, mode2) && (rand.nextInt(5) == 0);
	// Resort to flat types for the more expensive modes.
	flatTp = !nestedTypesAllowed(mode1, mode2);

	runner1 =
	TestRunner.getTestRunner(mode1, top, tmpDir.path, env, fileName, rand);
	runner2 =
	TestRunner.getTestRunner(mode2, top, tmpDir.path, env, fileName, rand);
	isolate =
	'Isolate (${tmpDir.path}) ${fp ? "" : "NO-"}FP ${ffi ? "" : "NO-"}FFI ${flatTp ? "" : "NO-"}FLAT : '
	'${runner1.description} - ${runner2.description}';

	start_time = DateTime.now().millisecondsSinceEpoch;
	current_time = start_time;
	report_time = start_time;
	end_time = start_time + max(0, time - timeout) * 1000;

	numTests = 0;
	numSuccess = 0;
	numSkipped = 0;
	numRerun = 0;
	numTimeout = 0;
	numDivergences = 0;
	timeoutSeeds = {};
	skippedSeeds = {};
	}

	bool sameArchitecture(String mode1, String mode2) =>
	((mode1.contains('arm32') && mode2.contains('arm32')) \|\|
	(mode1.contains('arm64') && mode2.contains('arm64')) \|\|
	(mode1.contains('x64') && mode2.contains('x64')) \|\|
	(mode1.contains('ia32') && mode2.contains('ia32')));

	bool ffiCapable(String mode1, String mode2) =>
	mode1.startsWith('jit') &&
	mode2.startsWith('jit') &&
	(!mode1.contains('arm') && !mode2.contains('arm'));

	bool nestedTypesAllowed(String mode1, String mode2) =>
	(!mode1.contains('arm') && !mode2.contains('arm'));

	bool timeIsUp() {
	if (time > 0) {
	current_time = DateTime.now().millisecondsSinceEpoch;
	if (current_time > end_time) {
	return true;
	}
	// Report every 10 minutes.
	if ((current_time - report_time) > (10 * 60 * 1000)) {
	print(
	'\n${isolate}: busy @${numTests} ${current_time - start_time} seconds....');
	report_time = current_time;
	}
	}
	return false;
	}

	void cleanup() {
	tmpDir.delete(recursive: true);
	}

	void showStatistics() {
	stdout.write('\rTests: $numTests Success: $numSuccess (Rerun: $numRerun) '
	'Skipped: $numSkipped Timeout: $numTimeout '
	'Divergences: $numDivergences');
	}

	void generateTest() {
	final file = File(fileName).openSync(mode: FileMode.write);
	DartFuzz(seed, fp, ffi, flatTp, file).run();
	file.closeSync();
	}

	void runTest() {
	TestResult result1 = runner1.run();
	TestResult result2 = runner2.run();
	var report = checkDivergence(result1, result2);
	if (report == ReportStatus.rerun && rerun) {
	print("\nCommencing re-run .... \n");
	numDivergences--;
	result1 = runner1.run();
	result2 = runner2.run();
	report = checkDivergence(result1, result2);
	if (report == ReportStatus.no_divergence) {
	print("\nNo error on re-run\n");
	numRerun++;
	}
	}
	if (report == ReportStatus.reported \|\|
	(!rerun && report == ReportStatus.rerun)) {
	showReproduce();
	}
	}

	ReportStatus checkDivergence(TestResult result1, TestResult result2) {
	if (result1.exitCode == result2.exitCode) {
	// No divergence in result code.
	switch (result1.exitCode) {
	case 0:
	// Both were successful, inspect output.
	if (result1.output == result2.output) {
	numSuccess++;
	} else {
	reportDivergence(result1, result2);
	return ReportStatus.reported;
	}
	break;
	case -sigkill:
	// Both had a time out.
	numTimeout++;
	timeoutSeeds.add(seed);
	break;
	default:
	// Both had an error.
	numSkipped++;
	skippedSeeds.add(seed);
	break;
	}
	} else {
	// Divergence in result code.
	if (trueDivergence) {
	// When only true divergences are requested, any divergence
	// with at least one time out or out of memory error is
	// treated as a regular time out or skipped test, respectively.
	if (result1.exitCode == -sigkill \|\| result2.exitCode == -sigkill) {
	numTimeout++;
	timeoutSeeds.add(seed);
	return ReportStatus.ignored;
	} else if (result1.exitCode == DartFuzz.oomExitCode \|\|
	result2.exitCode == DartFuzz.oomExitCode) {
	numSkipped++;
	skippedSeeds.add(seed);
	return ReportStatus.ignored;
	}
	}
	reportDivergence(result1, result2);
	// Exit codes outside [-255,255] are not due to Dart VM exits.
	if (result1.exitCode.abs() > 255 \|\| result2.exitCode.abs() > 255) {
	return ReportStatus.rerun;
	} else {
	return ReportStatus.reported;
	}
	}
	return ReportStatus.no_divergence;
	}

	String generateReport(TestResult result1, TestResult result2) {
	if (result1.exitCode == result2.exitCode) {
	return "output";
	} else {
	return "${result1.exitCode} vs ${result2.exitCode}";
	}
	}

	void printDivergenceOutput(String string, int numLines) {
	final lines = string.split('\n');
	print(lines.sublist(0, min(lines.length, numLines)).join('\n'));
	}

	void reportDivergence(TestResult result1, TestResult result2) {
	numDivergences++;
	String report = generateReport(result1, result2);
	print('\n${isolate}: !DIVERGENCE! $version:$seed (${report})');
	if (result1.exitCode == result2.exitCode) {
	if (numOutputLines > 0) {
	// Only report the actual output divergence details up to
	// numOutputLines, since this output may be lengthy and should be
	// reproducable anyway.
	print('\nout1:\n');
	printDivergenceOutput(result1.output, numOutputLines);
	print('\nout2:\n');
	printDivergenceOutput(result2.output, numOutputLines);
	}
	} else {
	// For any other divergence, always report what went wrong.
	if (result1.exitCode != 0) {
	print(
	'\nfail1:\n${result1.exitCode}\n${result1.output}\n${result1.stderr}\n');
	}
	if (result2.exitCode != 0) {
	print(
	'\nfail2:\n${result2.exitCode}\n${result2.output}\n${result2.stderr}\n');
	}
	}
	}

	void showReproduce() {
	print("\n-- BEGIN REPRODUCE --\n");
	print("DART SDK REVISION: $dartSdkRevision\n");
	print(
	"dart runtime/tools/dartfuzz/dartfuzz.dart --${fp ? "" : "no-"}fp --${ffi ? "" : "no-"}ffi "
	"--${flatTp ? "" : "no-"}flat "
	"--seed ${seed} fuzz.dart");
	print("\n-- RUN 1 --\n");
	runner1.printReproductionCommand();
	print("\n-- RUN 2 --\n");
	runner2.printReproductionCommand();
	print("\n-- END REPRODUCE --\n");
	}

	// Context.
	final Map<String, String> env;
	final int repeat;
	final int time;
	final int numOutputLines;
	final bool trueDivergence;
	final bool showStats;
	final String top;
	final String mode1;
	final String mode2;
	final bool rerun;
	final String dartSdkRevision;

	// Test.
	Random rand;
	Directory tmpDir;
	String fileName;
	TestRunner runner1;
	TestRunner runner2;
	bool fp;
	bool ffi;
	bool flatTp;
	String isolate;
	int seed;

	// Timing
	int start_time;
	int current_time;
	int report_time;
	int end_time;

	// Stats.
	int numTests;
	int numSuccess;
	int numSkipped;
	int numRerun;
	int numTimeout;
	int numDivergences;
	Set<int> timeoutSeeds;
	Set<int> skippedSeeds;
	}

	/// Class to start fuzz testing session.
	class DartFuzzTestSession {
	DartFuzzTestSession(
	this.isolates,
	this.repeat,
	this.time,
	this.numOutputLines,
	this.trueDivergence,
	this.showStats,
	String tp,
	this.mode1,
	this.mode2,
	this.rerun)
	: top = getTop(tp),
	dartSdkRevision = getDartSdkRevision(tp);

	start() async {
	print('\n\n Dart Fuzz Testing Session\n\n');
	print('Fuzz Version : ${version}');
	print('Dart SDK Revision : ${dartSdkRevision}');
	print('Isolates : ${isolates}');
	print('Tests : ${repeat}');
	if (time > 0) {
	print('Time : ${time} seconds');
	} else {
	print('Time : unlimited');
	}
	print('True Divergence : ${trueDivergence}');
	print('Show Stats : ${showStats}');
	print('Dart Dev : ${top}');
	// Fork.
	List<ReceivePort> ports = List();
	for (int i = 0; i < isolates; i++) {
	ReceivePort r = ReceivePort();
	ports.add(r);
	port = r.sendPort;
	await Isolate.spawn(run, this);
	}
	// Join.
	int divergences = 0;
	for (int i = 0; i < isolates; i++) {
	var d = await ports[i].first;
	divergences += d;
	}
	if (divergences == 0) {
	print('\nsuccess\n');
	} else {
	print('\nfailure ($divergences divergences)\n');
	exitCode = 1;
	}
	}

	static run(DartFuzzTestSession session) {
	int divergences = 0;
	try {
	final m1 = getMode(session.mode1, null);
	final m2 = getMode(session.mode2, m1);
	final fuzz = DartFuzzTest(
	Platform.environment,
	session.repeat,
	session.time,
	session.numOutputLines,
	session.trueDivergence,
	session.showStats,
	session.top,
	m1,
	m2,
	session.rerun,
	session.dartSdkRevision);
	divergences = fuzz.run();
	} catch (e) {
	print('Isolate: $e');
	}
	session.port.send(divergences);
	}

	// Picks a top directory (command line, environment, or current).
	static String getTop(String top) {
	if (top == null \|\| top == '') {
	top = Platform.environment['DART_TOP'];
	}
	if (top == null \|\| top == '') {
	top = Directory.current.path;
	}
	return top;
	}

	static String getDartSdkRevision(String top) {
	ProcessResult res =
	Process.runSync(Platform.resolvedExecutable, ['--version']);
	return res.stderr;
	}

	// Picks a mode (command line or random).
	static String getMode(String mode, String other) {
	// Random when not set.
	if (mode == null \|\| mode == '') {
	// Pick a mode at random (cluster), different from other.
	Random rand = Random();
	do {
	mode = clusterModes[rand.nextInt(clusterModes.length)];
	} while (mode == other);
	}
	// Verify mode.
	if (modes.contains(mode)) {
	return mode;
	}
	throw ('unknown mode: $mode');
	}

	// Context.
	final int isolates;
	final int repeat;
	final int time;
	final int numOutputLines;
	final bool trueDivergence;
	final bool showStats;
	final bool rerun;
	final String top;
	final String mode1;
	final String mode2;
	final String dartSdkRevision;

	// Passes each port to isolate.
	SendPort port;

	// Modes used on cluster runs.
	static const List<String> clusterModes = [
	'jit-debug-ia32',
	'jit-debug-x64',
	'jit-debug-arm32',
	'jit-debug-arm64',
	'jit-ia32',
	'jit-x64',
	'jit-arm32',
	'jit-arm64',
	'aot-debug-x64',
	'aot-x64',
	];

	// Modes not used on cluster runs because they have outstanding issues.
	static const List<String> nonClusterModes = [
	// Times out often:
	'aot-debug-arm32',
	'aot-debug-arm64',
	'aot-arm32',
	'aot-arm64',
	// Too many divergences (due to arithmetic):
	'js-x64',
	];

	// All modes.
	static List<String> modes = clusterModes + nonClusterModes;
	}

	/// Main driver for a fuzz testing session.
	main(List<String> arguments) {
	// Set up argument parser.
	final parser = ArgParser()
	..addOption('isolates', help: 'number of isolates to use', defaultsTo: '1')
	..addOption('repeat', help: 'number of tests to run', defaultsTo: '1000')
	..addOption('time', help: 'time limit in seconds', defaultsTo: '0')
	..addOption('num-output-lines',
	help:
	'number of output lines to be printed in the case of a divergence',
	defaultsTo: '200')
	..addFlag('true-divergence',
	negatable: true, help: 'only report true divergences', defaultsTo: true)
	..addFlag('show-stats',
	negatable: true, help: 'show session statistics', defaultsTo: true)
	..addOption('dart-top', help: 'explicit value for \$DART_TOP')
	..addOption('mode1', help: 'execution mode 1')
	..addOption('mode2', help: 'execution mode 2')
	..addFlag('rerun',
	negatable: true,
	help: 're-run if test only diverges on return code (not in the output)',
	defaultsTo: true)
	// Undocumented options for cluster runs.
	..addOption('shards',
	help: 'number of shards used in cluster run', defaultsTo: '1')
	..addOption('shard', help: 'shard id in cluster run', defaultsTo: '1')
	..addOption('output_directory',
	help: 'path to output (ignored)', defaultsTo: null)
	..addOption('output-directory',
	help: 'path to output (ignored)', defaultsTo: null);

	// Starts fuzz testing session.
	try {
	final results = parser.parse(arguments);
	final shards = int.parse(results['shards']);
	final shard = int.parse(results['shard']);
	if (shards > 1) {
	print('\nSHARD $shard OF $shards');
	}
	DartFuzzTestSession(
	int.parse(results['isolates']),
	int.parse(results['repeat']),
	int.parse(results['time']),
	int.parse(results['num-output-lines']),
	results['true-divergence'],
	results['show-stats'],
	results['dart-top'],
	results['mode1'],
	results['mode2'],
	results['rerun'])
	.start();
	} catch (e) {
	print('Usage: dart dartfuzz_test.dart [OPTIONS]\n${parser.usage}\n$e');
	exitCode = 255;
	}
	}