Use better hash computer.

pkg/analyzer/lib/src/generated/utilities_general.dart

 // Copyright (c) 2014, 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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.utilities.general;
 
 import 'dart:profiler';
 
 /**
+ * Jenkins hash function, optimized for small integers.
+ * Borrowed from sdk/lib/math/jenkins_smi_hash.dart.
+ */
+class JenkinsSmiHash {
+  static int combine(int hash, int value) {
+    hash = 0x1fffffff & (hash + value);
+    hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
+    return hash ^ (hash >> 6);
+  }
+
+  static int finish(int hash) {
+    hash = 0x1fffffff & (hash + ((0x03ffffff & hash) << 3));
+    hash = hash ^ (hash >> 11);
+    return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
+  }
+
+  static int hash2(a, b) => finish(combine(combine(0, a), b));
+
+  static int hash4(a, b, c, d) =>
+      finish(combine(combine(combine(combine(0, a), b), c), d));
+}
+
+/**
  * Helper class for gathering performance statistics.  This class is modeled on
  * the UserTag class in dart:profiler so that it can interoperate easily with
  * it.
  */
 abstract class PerformanceTag {
   /**
-   * Return the [PerformanceTag] that is initially current.  This is intended
-   * to track time when the system is performing unknown operations.
+   * Return a list of all [PerformanceTag]s which have been created.
    */
-  static PerformanceTag get UNKNOWN => _PerformanceTagImpl.UNKNOWN;
+  static List<PerformanceTag> get all => _PerformanceTagImpl.all.toList();
 
   /**
    * Return the current [PerformanceTag] for the isolate.
    */
   static PerformanceTag get current => _PerformanceTagImpl.current;
 
   /**
+   * Return the [PerformanceTag] that is initially current.  This is intended
+   * to track time when the system is performing unknown operations.
+   */
+  static PerformanceTag get UNKNOWN => _PerformanceTagImpl.UNKNOWN;
+
+  /**
    * Create a [PerformanceTag] having the given [label].  A [UserTag] will also
    * be created, having the same [label], so that performance information can
    * be queried using the observatory.
    */
   factory PerformanceTag(String label) = _PerformanceTagImpl;
 
   /**
-   * Return the label for this [PerformanceTag].
-   */
-  String get label;
-
-  /**
-   * Return a list of all [PerformanceTag]s which have been created.
-   */
-  static List<PerformanceTag> get all => _PerformanceTagImpl.all.toList();
-
-  /**
    * Return the total number of milliseconds that this [PerformanceTag] has
    * been the current [PerformanceTag] for the isolate.
    *
    * This call is safe even if this [PerformanceTag] is current.
    */
   int get elapsedMs;
 
   /**
+   * Return the label for this [PerformanceTag].
+   */
+  String get label;
+
+  /**
    * Make this the current tag for the isolate, and return the previous tag.
    */
   PerformanceTag makeCurrent();
 
   /**
    * Reset the total time tracked by all [PerformanceTag]s to zero.
    */
   static void reset() {
     for (_PerformanceTagImpl tag in _PerformanceTagImpl.all) {
       tag.stopwatch.reset();
     }
   }
 }
 
 class _PerformanceTagImpl implements PerformanceTag {
   /**
    * The current performance tag for the isolate.
    */
   static _PerformanceTagImpl current = UNKNOWN;
 
   static final _PerformanceTagImpl UNKNOWN = new _PerformanceTagImpl('unknown');
 
   /**
    * A list of all performance tags that have been created so far.
    */
   static List<_PerformanceTagImpl> all = <_PerformanceTagImpl>[];
 
-  @override
-  String get label => userTag.label;
-
   /**
    * The [UserTag] associated with this [PerformanceTag].
    */
   final UserTag userTag;
 
   /**
    * Stopwatch tracking the amount of time this [PerformanceTag] has been the
    * current tag for the isolate.
    */
   final Stopwatch stopwatch;
 
   _PerformanceTagImpl(String label)
       : userTag = new UserTag(label), stopwatch = new Stopwatch() {
     all.add(this);
   }
 
   @override
+  int get elapsedMs => stopwatch.elapsedMilliseconds;
+
+  @override
+  String get label => userTag.label;
+
+  @override
   PerformanceTag makeCurrent() {
     if (identical(this, current)) {
       return current;
     }
     _PerformanceTagImpl previous = current;
     previous.stopwatch.stop();
     stopwatch.start();
     current = this;
     userTag.makeCurrent();
     return previous;
   }
-
-  @override
-  int get elapsedMs => stopwatch.elapsedMilliseconds;
 }