| /* |
| * Copyright (c) 2021, 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 8268347 |
| * @summary Nested locks optimization may create unbalanced monitor enter/exit code |
| * |
| * @run main/othervm -XX:-BackgroundCompilation |
| * -XX:CompileCommand=dontinline,TestNestedLocksElimination::foo |
| * -XX:CompileCommand=dontinline,TestNestedLocksElimination::getNext |
| * -XX:CompileCommand=dontinline,TestNestedLocksElimination::getHolder |
| * TestNestedLocksElimination |
| */ |
| |
| import java.util.LinkedList; |
| |
| public class TestNestedLocksElimination { |
| |
| private LinkedList<char[]> buffers = new LinkedList<>(); |
| private boolean complete = false; |
| private int bufferSize; |
| |
| void foo(char[] ca) { |
| // Don't inline dummy method |
| } |
| |
| // Don't inline |
| char[] getNext(int length, int count) { |
| if (this.buffers.isEmpty()) { |
| return new char[100]; |
| } |
| char[] b = (char[]) this.buffers.getFirst(); |
| if (count >= 100) { |
| this.complete = true; |
| this.buffers.clear(); // empty |
| } |
| return b; |
| } |
| |
| synchronized boolean isComplete() { |
| return this.complete; |
| } |
| |
| synchronized boolean availableSegment() { |
| return (buffers.isEmpty() == false); |
| } |
| |
| // Don't inline |
| TestNestedLocksElimination getHolder(TestNestedLocksElimination s1, TestNestedLocksElimination s2, int count) { |
| return (count & 7) == 0 ? s2 : s1; |
| } |
| |
| int test(TestNestedLocksElimination s1, TestNestedLocksElimination s2, int maxToSend) { |
| boolean isComplete = true; |
| boolean availableSegment = false; |
| int size = 0; |
| int count = 0; |
| do { |
| TestNestedLocksElimination s = getHolder(s1, s2, count++); |
| |
| synchronized(s) { |
| isComplete = s.isComplete(); |
| availableSegment = s.availableSegment(); |
| } |
| |
| synchronized (this) { |
| size = 0; |
| while (size < maxToSend) { |
| char[] b = null; |
| // This is outer Lock region for object 's'. |
| // Locks from following inlined methods are "nested" |
| // because they reference the same object. |
| synchronized(s) { |
| b = s.getNext(maxToSend - size, count); |
| |
| // The next is bi-morphic call with both calls inlined. |
| // But one is synchronized and the other is not. |
| // Class check for bi-morphic call is loop invariant |
| // and will trigger loop unswitching. |
| // Loop unswitching will create two versions of loop |
| // with gollowing calls inlinined in both versions. |
| |
| isComplete = s.isComplete(); |
| |
| // The next synchronized method availableSegment() is |
| // inlined and its Lock will be "coarsened" with Unlock |
| // in version of loop with inlined synchronized method |
| // isComplete(). |
| // Nested Lock Optimization will mark only this Unlock |
| // as nested (as part of "nested" pair lock/unlock). |
| // Locks elimination will remove "coarsened" Lock from |
| // availableSegment() method leaving unmatched unlock. |
| |
| availableSegment = s.availableSegment(); |
| } |
| foo(b); |
| size += b.length; |
| } |
| } |
| } while (availableSegment == true || isComplete == false); |
| return size; |
| } |
| |
| public static void main(String[] args) { |
| int count = 0; |
| int n = 0; |
| |
| TestNestedLocksElimination t = new TestNestedLocksElimination(); |
| TestNestedLocksElimination s1 = new TestNestedLocksElimination(); |
| TestNestedLocksElimination s2 = new TestNestedLocksEliminationSub(); |
| |
| char[] c = new char[100]; |
| while (n++ < 20_000) { |
| s1.buffers.add(c); |
| s2.buffers.add(c); |
| count += t.test(s1, s2, 10000); |
| } |
| |
| System.out.println(" count: " + count); |
| } |
| } |
| |
| class TestNestedLocksEliminationSub extends TestNestedLocksElimination { |
| public boolean isComplete() { |
| return true; |
| } |
| } |
| |