1 /* 2 * Copyright (c) 2019 SAP SE. 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 8221083 27 * @requires vm.gc.Serial 28 * @requires vm.bits == 64 & vm.opt.final.UseCompressedOops == true 29 * @summary On ppc64, C1 erroneously emits a 32-bit compare instruction for oop compares. 30 * @modules java.base/jdk.internal.misc:+open 31 * @library /test/lib / 32 * @build sun.hotspot.WhiteBox 33 * @run driver ClassFileInstaller sun.hotspot.WhiteBox 34 * @run main/othervm -Xbatch -XX:-UseTLAB -Xmx4m -XX:+UseSerialGC -XX:HeapBaseMinAddress=0x700000000 35 * -XX:CompileCommand=compileonly,compiler.codegen.TestOopCmp::nullTest 36 * -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xbootclasspath/a:. 37 * compiler.codegen.TestOopCmp 38 * @author volker.simonis@gmail.com 39 */ 40 41 package compiler.codegen; 42 43 import sun.hotspot.WhiteBox; 44 45 public class TestOopCmp { 46 47 private static Object nullObj = null; 48 49 public static boolean nullTest(Object o) { 50 if (o == nullObj) { 51 return true; 52 } else { 53 return false; 54 } 55 } 56 57 public static void main(String args[]) { 58 59 WhiteBox WB = WhiteBox.getWhiteBox(); 60 61 // The test is started with -XX:HeapBaseMinAddress=0x700000000 and a 62 // small heap of only 4mb. This works pretty reliable and at least on 63 // Linux/Windows we will get a heap starting at 0x700000000. 64 // The test also runs with -XX:+UseSerialGC which means that we'll get 65 // eden starting at 0x700000000. 66 // Calling 'System.gc()' will clean up all the objects from eden, so if 67 // eden starts at 0x700000000 the first allocation right after the 68 // system GC will be allcoated right at address 0x700000000. 69 System.gc(); 70 String s = new String("I'm not null!!!"); 71 if (WB.getObjectAddress(s) == 0x700000000L) { 72 System.out.println("Got object at address 0x700000000"); 73 } 74 75 // We call 'nullTest()' with the newly allocated String object. If it was 76 // allocated at 0x700000000, its 32 least-significant bits will be 0 and a 77 // 32-bit comparison with 'nullObj' (which is 'null') will yield true and 78 // result in a test failure. 79 // If the code generated for 'nullTest()' correctly performs a 64-bit 80 // comparison or if we didn't manage to allcoate 's' at 0x700000000 the 81 // test will always succeed. 82 for (int i = 0; i < 30_000; i++) { 83 if (nullTest(s)) { 84 throw new RuntimeException("Comparing non-null object with null returned 'true'"); 85 } 86 } 87 } 88 }