1 /*
   2  * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package org.openjdk.bench.vm.compiler;
  24 
  25 import org.openjdk.jmh.annotations.Benchmark;
  26 import org.openjdk.jmh.annotations.BenchmarkMode;
  27 import org.openjdk.jmh.annotations.Mode;
  28 import org.openjdk.jmh.annotations.OutputTimeUnit;
  29 import org.openjdk.jmh.annotations.Scope;
  30 import org.openjdk.jmh.annotations.Setup;
  31 import org.openjdk.jmh.annotations.State;
  32 
  33 import java.util.concurrent.TimeUnit;
  34 
  35 /**
  36  * Benchmark measuring the gain of removing array bound checks in various cases
  37  */
  38 @BenchmarkMode(Mode.AverageTime)
  39 @OutputTimeUnit(TimeUnit.NANOSECONDS)
  40 @State(Scope.Thread)
  41 public class ArrayBoundCheckRemoval {
  42 
  43     private int[] a;
  44     private int j, u, v;
  45 
  46     @Setup
  47     public void setup() {
  48         a = new int[200];
  49     }
  50 
  51     @Benchmark
  52     public int[] testForLoopAccess() throws Exception {
  53         int[] a = this.a;
  54         for (int i = 0; i < a.length; i++) {
  55             a[i] = i;
  56         }
  57         return a;
  58     }
  59 
  60     @Benchmark
  61     public int[] testBubblesortStripped() throws Exception {
  62         int[] a = this.a;
  63         int limit = a.length;
  64         int st = -1;
  65 
  66         while (st < limit) {
  67             st++;
  68             limit--;
  69             for (j = st; j < limit; j++) {
  70                 u = a[j];
  71                 v = a[j + 1];
  72             }
  73         }
  74         return a;
  75     }
  76 
  77     @Benchmark
  78     public int[] testBubblesort() throws Exception {
  79         int[] a = this.a;
  80         int j1;
  81         int limit = a.length;
  82         int st = -1;
  83         while (st < limit) {
  84             boolean flipped = false;
  85             st++;
  86             limit--;
  87             for (j1 = st; j1 < limit; j1++) {
  88                 if (a[j1] > a[j1 + 1]) {
  89                     int T = a[j1];
  90                     a[j1] = a[j1 + 1];
  91                     a[j1 + 1] = T;
  92                     flipped = true;
  93                 }
  94             }
  95             if (!flipped) {
  96                 return a;
  97             }
  98             flipped = false;
  99             for (j1 = limit; --j1 >= st; ) {
 100                 if (a[j1] > a[j1 + 1]) {
 101                     int T = a[j1];
 102                     a[j1] = a[j1 + 1];
 103                     a[j1 + 1] = T;
 104                     flipped = true;
 105                 }
 106             }
 107             if (!flipped) {
 108                 return a;
 109             }
 110         }
 111         return a;
 112     }
 113 
 114 }