Java example source code file (C1ObjectSpillInLogicOp.java)

This example Java source code file (C1ObjectSpillInLogicOp.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

atomicreferencearray, c1objectspillinlogicop, integer

The C1ObjectSpillInLogicOp.java Java example source code

/*
 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 8027751
 * @summary C1 crashes generating G1 post-barrier in Unsafe.getAndSetObject() intrinsic because of the new value spill
 * @run main/othervm -XX:+UseG1GC C1ObjectSpillInLogicOp
 *
 * G1 barriers use logical operators (xor) on T_OBJECT mixed with T_LONG or T_INT.
 * The current implementation of logical operations on x86 in C1 doesn't allow for long operands to be on stack.
 * There is a special code in the register allocator that forces long arguments in registers on x86. However T_OBJECT
 * can be spilled just fine, and in that case the xor emission will fail.
 */

import java.util.concurrent.atomic.*;

public class C1ObjectSpillInLogicOp {
  public static void main(String[] args) {
    AtomicReferenceArray<Integer> x = new AtomicReferenceArray(128);
    Integer y = new Integer(0);
    for (int i = 0; i < 50000; i++) {
      x.getAndSet(i % x.length(), y);
    }
  }
}