Speed up kernel sanity checks.

pkg/kernel/test/check_bench.dart

+// Copyright (c) 2016, 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.
+
+import 'dart:io';
+import 'package:kernel/checks.dart';
+import 'package:kernel/kernel.dart';
+
+final String usage = '''
+Usage: check_bench FILE.dill
+
+Measures the time it takes to run sanity checks on the given program.
+''';
+
+main(List<String> args) {
+  if (args.length != 1) {
+    print(usage);
+    exit(1);
+  }
+  var program = loadProgramFromBinary(args[0]);
+  var watch = new Stopwatch()..start();
+  runSanityChecks(program);
+  print('Cold: ${watch.elapsedMilliseconds} ms');
+  const int warmUpTrials = 20;
+  for (int i = 0; i < warmUpTrials; ++i) {
+    runSanityChecks(program);
+  }
+  watch.reset();
+  const int numberOfTrials = 100;
+  for (int i = 0; i < numberOfTrials; ++i) {
+    runSanityChecks(program);
+  }
+  double millisecondsPerRun = watch.elapsedMilliseconds / numberOfTrials;
+  print('Hot:  $millisecondsPerRun ms');
+}