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17985
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1 /*
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2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 */
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23
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24 /*
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25 * @test
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26 * @bug 8046516
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27 * @summary Segmentation fault in JVM (easily reproducible)
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28 * @run main/othervm -XX:-TieredCompilation -Xbatch TestLogSum
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29 * @author jackkamm@gmail.com
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30 */
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31
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32 import java.util.Arrays;
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33 import java.util.HashMap;
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34 import java.util.List;
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35 import java.util.Map;
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36 public class TestLogSum {
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37 public static void main(String[] args) {
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38 double sum;
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39
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40 for (int i = 0; i < 6; i++) {
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41 for (int n = 2; n < 30; n++) {
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42 for (int j = 1; j <= n; j++) {
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43 for (int k = 1; k <= j; k++) {
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44 // System.out.println(computeSum(k, j));
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45 sum = computeSum(k, j);
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46 }
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47 }
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48 }
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49 }
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50 }
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51
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52 private static Map<List<Integer>, Double> cache = new HashMap<List<Integer>, Double>();
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53 public static double computeSum(int x, int y) {
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54 List<Integer> key = Arrays.asList(new Integer[] {x, y});
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55
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56 if (!cache.containsKey(key)) {
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57
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58 // explicitly creating/updating a double[] array, instead of using the LogSumArray wrapper object, will prevent the error
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59 LogSumArray toReturn = new LogSumArray(x);
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60
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61 // changing loop indices will prevent the error
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62 // in particular, for(z=0; z<x-1; z++), and then using z+1 in place of z, will not produce error
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63 for (int z = 1; z < x+1; z++) {
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64 double logSummand = Math.log(z + x + y);
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65 toReturn.addLogSummand(logSummand);
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66 }
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67
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68 // returning the value here without cacheing it will prevent the segfault
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69 cache.put(key, toReturn.retrieveLogSum());
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70 }
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71 return cache.get(key);
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72 }
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73
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74 /*
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75 * Given a bunch of logarithms log(X),log(Y),log(Z),...
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76 * This class is used to compute the log of the sum, log(X+Y+Z+...)
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77 */
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78 private static class LogSumArray {
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79 private double[] logSummandArray;
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80 private int currSize;
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81
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82 private double maxLogSummand;
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83
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84 public LogSumArray(int maxEntries) {
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85 this.logSummandArray = new double[maxEntries];
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86
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87 this.currSize = 0;
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88 this.maxLogSummand = Double.NEGATIVE_INFINITY;
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89 }
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90
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91 public void addLogSummand(double logSummand) {
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92 logSummandArray[currSize] = logSummand;
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93 currSize++;
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94 // removing this line will prevent the error
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95 maxLogSummand = Math.max(maxLogSummand, logSummand);
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96 }
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97
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98 public double retrieveLogSum() {
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99 if (maxLogSummand == Double.NEGATIVE_INFINITY) return Double.NEGATIVE_INFINITY;
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100
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101 assert currSize <= logSummandArray.length;
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102
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103 double factorSum = 0;
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104 for (int i = 0; i < currSize; i++) {
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105 factorSum += Math.exp(logSummandArray[i] - maxLogSummand);
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106 }
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107
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108 return Math.log(factorSum) + maxLogSummand;
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109 }
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110 }
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111 }
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