1 /* 2 * Copyright (c) 2016, 2018, 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 24 /* 25 * @test 26 * @bug 8159016 8202949 8203915 27 * @summary Tests correct dominator information after over-unrolling a loop. 28 * @requires vm.gc == "Parallel" | vm.gc == "null" 29 * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:+UnlockDiagnosticVMOptions 30 * -Xcomp -XX:-TieredCompilation -XX:-UseSwitchProfiling 31 * -XX:-UseCountedLoopSafepoints -XX:LoopUnrollLimit=250 32 * -XX:-UseG1GC -XX:+UseParallelGC compiler.loopopts.TestOverunrolling 33 */ 34 35 package compiler.loopopts; 36 37 public class TestOverunrolling { 38 test1(int arg)39 public static Object test1(int arg) { 40 Object arr[] = new Object[3]; 41 int lim = (arg & 3); 42 // The pre loop is executed for one iteration, initializing p[0]. 43 // The main loop is unrolled twice, initializing p[1], p[2], p[3] and p[4]. 44 // The p[3] and p[4] stores are always out of bounds and removed. However, 45 // C2 is unable to remove the "over-unrolled", dead main loop. As a result, 46 // there is a control path from the main loop to the post loop without a 47 // memory path (because the last store was replaced by TOP). We crash 48 // because we use a memory edge from a non-dominating region. 49 for (int i = 0; i < lim; ++i) { 50 arr[i] = new Object(); 51 } 52 // Avoid EA 53 return arr; 54 } 55 56 public static long lFld = 0; 57 public static volatile double dFld = 0; 58 test2()59 public static void test2() { 60 int iArr[] = new int[10]; 61 // The inner for-loop is overunrolled because we fail to determine 62 // the constant lower and upper bound (6,8]. After unrolling multiple times, 63 // the range check dependent CastII/ConvI2L emitted for the iArr access become 64 // TOP because index 'j' is out of bounds. As a result, the memory graph is 65 // corrupted with memory consuming nodes still being reachable because the dead 66 // loop is not (yet) removed (Opaque1 nodes are still guarding the bounds). 67 for (int i = 6; i < 10; i++) { 68 for (int j = 8; j > i; j--) { 69 int k = 1; 70 do { 71 iArr[j] = 0; 72 switch (k) { 73 case 1: 74 lFld = 0; 75 break; 76 case 10: 77 dFld = 0; 78 break; 79 } 80 } while (++k < 1); 81 } 82 } 83 } 84 85 // Similar to test2 but we cannot statically determine the upper bound of 86 // the inner for loop and can therefore not prevent over-unrolling. test3(int[] array)87 public static void test3(int[] array) { 88 int[] iArr = new int[8]; 89 for (int i = 0; i < array.length; i++) { 90 for (int j = 5; j < i; j++) { 91 int k = 1; 92 do { 93 iArr[j] = 0; 94 switch (k) { 95 case 1: 96 lFld = 0; 97 break; 98 case 10: 99 dFld = 0; 100 break; 101 } 102 } while (++k < 1); 103 } 104 } 105 } 106 107 // Similar to test3 but with negative stride and constant outer loop limit test4(int[] array, boolean store)108 public static void test4(int[] array, boolean store) { 109 int[] iArr = new int[8]; 110 for (int i = -8; i < 8; i++) { 111 for (int j = 5; j > i; j--) { 112 int k = 1; 113 do { 114 if (store) { 115 iArr[j] = 0; 116 } 117 switch (k) { 118 case 1: 119 lFld = 0; 120 break; 121 case 10: 122 dFld = 0; 123 break; 124 } 125 } while (++k < 1); 126 } 127 } 128 } 129 130 // The inner for-loop is over-unrolled and vectorized resulting in 131 // a crash in the matcher because the memory input to a vector is top. test5(int[] array)132 public static int test5(int[] array) { 133 int result = 0; 134 int[] iArr = new int[8]; 135 for (int i = 0; i < array.length; i++) { 136 for (int j = 5; j < i; j++) { 137 iArr[j] += array[j]; 138 result += array[j]; 139 } 140 } 141 return result; 142 } 143 main(String args[])144 public static void main(String args[]) { 145 for (int i = 0; i < 42; ++i) { 146 test1(i); 147 } 148 test2(); 149 int[] array = new int[8]; 150 test3(array); 151 test4(array, false); 152 test5(array); 153 } 154 } 155 156