1 /* 2 * Copyright (c) 2014, 2014, Oracle and/or its affiliates. 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 package jdk.vm.ci.hotspot; 24 25 import java.util.Collection; 26 import java.util.HashSet; 27 import java.util.Set; 28 import java.util.concurrent.ConcurrentLinkedQueue; 29 30 import jdk.vm.ci.meta.JavaConstant; 31 import jdk.vm.ci.meta.SpeculationLog; 32 33 public class HotSpotSpeculationLog implements SpeculationLog { 34 35 /** Written by the C++ code that performs deoptimization. */ 36 private volatile Object lastFailed; 37 38 /** All speculations that have caused a deoptimization. */ 39 private Set<SpeculationReason> failedSpeculations; 40 41 /** Strong references to all reasons embedded in the current nmethod. */ 42 private volatile Collection<SpeculationReason> speculations; 43 44 @Override 45 public synchronized void collectFailedSpeculations() { 46 if (lastFailed != null) { 47 if (failedSpeculations == null) { 48 failedSpeculations = new HashSet<>(2); 49 } 50 failedSpeculations.add((SpeculationReason) lastFailed); 51 lastFailed = null; 52 speculations = null; 53 } 54 } 55 56 @Override 57 public synchronized boolean maySpeculate(SpeculationReason reason) { 58 if (failedSpeculations != null && failedSpeculations.contains(reason)) { 59 return false; 60 } 61 return true; 62 } 63 64 @Override 65 public JavaConstant speculate(SpeculationReason reason) { 66 assert maySpeculate(reason); 67 68 /* 69 * Objects referenced from nmethods are weak references. We need a strong reference to the 70 * reason objects that are embedded in nmethods, so we add them to the speculations 71 * collection. 72 */ 73 if (speculations == null) { 74 synchronized (this) { 75 if (speculations == null) { 76 speculations = new ConcurrentLinkedQueue<>(); 77 } 78 } 79 } 80 speculations.add(reason); 81 82 return HotSpotObjectConstantImpl.forObject(reason); 83 } 84 85 @Override 86 public synchronized boolean hasSpeculations() { 87 return speculations != null && !speculations.isEmpty(); 88 } 89 }