1 /*
   2  * Copyright (c) 2017, 2018, Red Hat, Inc. 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 TestMaybeNullUnsafeAccess
  26  * @summary cast on before unsafe access moved in dominating null check null path causes crash
  27  * @key gc
  28  * @library /testlibrary
  29  *
  30  * @run main/othervm -XX:-UseOnStackReplacement -XX:-BackgroundCompilation -XX:-TieredCompilation TestMaybeNullUnsafeAccess
  31  *
  32  */
  33 
  34 import sun.misc.Unsafe;
  35 
  36 import java.lang.reflect.Field;
  37 
  38 import com.oracle.java.testlibrary.*;
  39 
  40 public class TestMaybeNullUnsafeAccess {
  41 
  42     static final sun.misc.Unsafe UNSAFE = Utils.getUnsafe();
  43     static final long F_OFFSET;
  44 
  45     static class A {
  46         int f;
  47     }
  48 
  49     static {
  50         try {
  51             Field fField = A.class.getDeclaredField("f");
  52             F_OFFSET = UNSAFE.objectFieldOffset(fField);
  53         } catch (Exception e) {
  54             throw new RuntimeException(e);
  55         }
  56     }
  57 
  58     static A test_helper(Object o) {
  59         return (A) o;
  60     }
  61 
  62     static int test(Object o) {
  63         int f = 0;
  64         for (int i = 0; i < 100; i++) {
  65             A a = test_helper(o);
  66             f = UNSAFE.getInt(a, F_OFFSET);
  67         }
  68         return f;
  69     }
  70 
  71     static public void main(String[] args) {
  72         A a = new A();
  73         for (int i = 0; i < 20000; i++) {
  74             test_helper(null);
  75             test_helper(a);
  76             test(a);
  77         }
  78     }
  79 
  80 }