hotspot/test/compiler/7190310/Test7190310.java
author kvn
Mon, 20 Aug 2012 09:58:58 -0700
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child 15212 bbda5353d846
permissions -rw-r--r--
7190310: Inlining WeakReference.get(), and hoisting $referent may lead to non-terminating loops Summary: In C2 add software membar after load from Reference.referent field to prevent commoning of loads across safepoint since GC can change its value. In C1 always generate Reference.get() intrinsic. Reviewed-by: roland, twisti, dholmes, johnc
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/*
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 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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/*
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 * Manual test
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 */
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import java.lang.ref.*;
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public class Test7190310 {
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  private static Object str = new Object() {
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    public String toString() {
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      return "The Object";
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    }
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    protected void finalize() throws Throwable {
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      System.out.println("The Object is being finalized");
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      super.finalize();
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    }
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  };
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  private final static ReferenceQueue<Object> rq =
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      new ReferenceQueue<Object>();
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  private final static WeakReference<Object> wr =
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      new WeakReference<Object>(str, rq);
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  public static void main(String[] args)
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      throws InterruptedException {
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    Thread reader = new Thread() {
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      public void run() {
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        while (wr.get() != null) {
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        }
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        System.out.println("wr.get() returned null");
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      }
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    };
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    Thread queueReader = new Thread() {
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      public void run() {
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        try {
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          Reference<? extends Object> ref = rq.remove();
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          System.out.println(ref);
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          System.out.println("queueReader returned, ref==wr is "
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              + (ref == wr));
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        } catch (InterruptedException e) {
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          System.err.println("Sleep interrupted - exiting");
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        }
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      }
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    };
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    reader.start();
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    queueReader.start();
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    Thread.sleep(1000);
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    str = null;
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    System.gc();
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  }
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}
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