A/B fasta performance measurement harness

pkg/front_end/tool/fasta/abcompile.dart

Index: pkg/front_end/tool/fasta/abcompile.dart
diff --git a/pkg/front_end/tool/fasta/abcompile.dart b/pkg/front_end/tool/fasta/abcompile.dart
new file mode 100644
index 0000000000000000000000000000000000000000..3bedc4d110a375dca6ecd26f72d04fb26b4ccfa9
--- /dev/null
+++ b/pkg/front_end/tool/fasta/abcompile.dart
@@ -0,0 +1,160 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:math';
+import 'dart:io';
+
+import 'standard_deviation.dart';
+
+const String bRootPath = const String.fromEnvironment("bRoot");
+const int iterations = const int.fromEnvironment("iterations", defaultValue: 1);
+
+/// Compare the performance of two different fast implementations
+/// by alternately launching the compile application in this directory
+/// and the compile application location in the repo specified by "bRoot"
+/// via -DbRoot=/absolute/path/to/other/sdk/repo
+main(List<String> args) async {
+  print(args);
+  if (bRootPath == null) {
+    print('Expected -DbRoot=/absolute/path/to/other/sdk/repo');
+    exit(1);
+  }
+
+  // The root of this Dart SDK repo "A"
+  Uri aRoot = Platform.script.resolve('../../../..');
+
+  // The root of the other Dart SDK repo "B"
+  Uri bRoot = new Uri.directory(bRootPath);
+
+  // Sanity check
+  String relPath = 'pkg/front_end/tool/fasta/compile.dart';
+  Uri aCompile = aRoot.resolve(relPath);
+  if (!new File(aCompile.toFilePath()).existsSync()) {
+    print('Failed to find $aCompile');
+    exit(1);
+  }
+  Uri bCompile = bRoot.resolve(relPath);
+  if (!new File(bCompile.toFilePath()).existsSync()) {
+    print('Failed to find $bCompile');
+    exit(1);
+  }
+
+  print('Comparing:');
+  print('A: $aCompile');
+  print('B: $bCompile');
+  print('');
+
+  List<double> aCold = <double>[];
+  List<double> aWarm = <double>[];
+  List<double> bCold = <double>[];
+  List<double> bWarm = <double>[];
+  for (int count = 0; count < 15; ++count) {
+    await run(aRoot, aCompile, args, aCold, aWarm);
+    await run(bRoot, bCompile, args, bCold, bWarm);
+  }
+
+  print('');
+  print('Raw data:');
+  print('A cold, A warm, B cold, B warm');
+  for (int index = 0; index < aCold.length; ++index) {
+    print('${aCold[index]}, ${aWarm[index]}, ${bCold[index]}, ${bWarm[index]}');
+  }
+
+  double aColdMean = average(aCold);
+  double aWarmMean = average(aWarm);
+  double bColdMean = average(bCold);
+  double bWarmMean = average(bWarm);
+
+  print('');
+  print('Average:');
+  print('$aColdMean, $aWarmMean, $bColdMean, $bWarmMean');
+
+  double aColdStdDev = standardDeviation(aColdMean, aCold);
+  double aWarmStdDev = standardDeviation(aWarmMean, aWarm);
+  double bColdStdDev = standardDeviation(bColdMean, bCold);
+  double bWarmStdDev = standardDeviation(bWarmMean, bWarm);
+
+  double aColdStdDevMean = standardDeviationOfTheMean(aCold, aColdStdDev);
+  double aWarmStdDevMean = standardDeviationOfTheMean(aWarm, aWarmStdDev);
+  double bColdStdDevMean = standardDeviationOfTheMean(bCold, bColdStdDev);
+  double bWarmStdDevMean = standardDeviationOfTheMean(bWarm, bWarmStdDev);
+
+  print('');
+  print('Uncertainty:');
+  print(
+      '$aColdStdDevMean, $aWarmStdDevMean, $bColdStdDevMean, $bWarmStdDevMean');
+
+  double coldDelta = aColdMean - bColdMean;
+  double coldStdDevMean =
+      sqrt(pow(aColdStdDevMean, 2) + pow(bColdStdDevMean, 2));
+  double warmDelta = aWarmMean - bWarmMean;
+  double warmStdDevMean =
+      sqrt(pow(aWarmStdDevMean, 2) + pow(bWarmStdDevMean, 2));
+
+  print('');
+  print('Summary:');
+  print('  A cold start - B cold start : $coldDelta');
+  print('  Uncertainty                 : $coldStdDevMean');
+  print('');
+  print('  A warm runs - B warm runs   : $warmDelta');
+  print('  Uncertainty                 : $warmStdDevMean');
+}
+
+const String _wroteProgram = 'Wrote program to';
+const String _coldStart = 'Cold start (first run):';
+const String _warmRun = 'Warm run average (runs #4';
+
+/// Launch the specified dart program, forwarding all arguments and environment
+/// that was passed to this program
+Future<Null> run(Uri workingDir, Uri dartApp, List<String> args,
+    List<double> cold, List<double> warm) async {
+  print('Running $dartApp');
+
+  void processLine(String line) {
+    if (line.contains(_wroteProgram)) {
+      // Show progress
+      stdout
+        ..write('.')
+        ..flush();
+      return;
+    }
+    int index = line.indexOf(_coldStart);
+    if (index >= 0) {
+      cold.add(double.parse(line.substring(index + _coldStart.length)));
+      print('\ncold: ${cold.last}');
+      return;
+    }
+    index = line.indexOf(_warmRun);
+    if (index >= 0) {
+      index = line.indexOf(':', index + _warmRun.length);
+      warm.add(double.parse(line.substring(index + 1)));
+      print('warm: ${warm.last}');
+      return;
+    }
+  }
+
+  String workingDirPath = workingDir.toFilePath();
+  List<String> procArgs = <String>[
+    '-Diterations=$iterations',
+    dartApp.toFilePath()
+  ];
+  procArgs.addAll(args);
+
+  Process process = await Process.start(Platform.executable, procArgs,
+      workingDirectory: workingDirPath);
+  stderr.addStream(process.stderr);
+  StreamSubscription<String> stdOutSubscription;
+  stdOutSubscription = process.stdout
+      .transform(UTF8.decoder)
+      .transform(new LineSplitter())
+      .listen(processLine, onDone: () {
+    stdOutSubscription.cancel();
+  }, onError: (e) {
+    print('Error: $e');
+    stdOutSubscription.cancel();
+  });
+  int code = await process.exitCode;
+  if (code != 0) {
+    throw 'fail: $code';
+  }
+  print('');
+}