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.HashMap;
  26 import java.util.HashSet;
  27 import java.util.Set;
  28 import java.util.Map;
  29 
  30 import jdk.vm.ci.meta.JavaConstant;
  31 import jdk.vm.ci.meta.SpeculationLog;
  32 
  33 public class HotSpotSpeculationLog implements SpeculationLog {
  34     public static final class HotSpotSpeculation extends Speculation {
  35         private JavaConstant encoding;
  36 
  37         HotSpotSpeculation(SpeculationReason reason, JavaConstant encoding) {
  38             super(reason);
  39             this.encoding = encoding;
  40         }
  41 
  42         public JavaConstant getEncoding() {
  43             return encoding;
  44         }
  45     }
  46 
  47     /** Written by the C++ code that performs deoptimization. */
  48     private volatile long lastFailed;
  49 
  50     /** All speculations that have caused a deoptimization. */
  51     private Set<SpeculationReason> failedSpeculations;
  52 
  53     /** Strong references to all reasons embedded in the current nmethod. */
  54     private Map<Long, SpeculationReason> speculations;
  55 
  56     private long currentSpeculationID;
  57 
  58     @Override
  59     public synchronized void collectFailedSpeculations() {
  60         if (lastFailed != 0) {
  61             if (failedSpeculations == null) {
  62                 failedSpeculations = new HashSet<>(2);
  63             }
  64             if (speculations != null) {
  65                 SpeculationReason lastFailedSpeculation = speculations.get(lastFailed);
  66                 if (lastFailedSpeculation != null) {
  67                     failedSpeculations.add(lastFailedSpeculation);
  68                 }
  69                 lastFailed = 0;
  70                 speculations = null;
  71             }
  72         }
  73     }
  74 
  75     @Override
  76     public synchronized boolean maySpeculate(SpeculationReason reason) {
  77         if (failedSpeculations != null && failedSpeculations.contains(reason)) {
  78             return false;
  79         }
  80         return true;
  81     }
  82 
  83     @Override
  84     public synchronized Speculation speculate(SpeculationReason reason) {
  85         if (speculations == null) {
  86             speculations = new HashMap<>();
  87         }
  88         speculations.put(++currentSpeculationID, reason);
  89         return new HotSpotSpeculation(reason, JavaConstant.forLong(currentSpeculationID));
  90     }
  91 
  92     @Override
  93     public synchronized boolean hasSpeculations() {
  94         return speculations != null && !speculations.isEmpty();
  95     }
  96 
  97     @Override
  98     public synchronized Speculation lookupSpeculation(JavaConstant constant) {
  99         if (constant.isDefaultForKind()) {
 100             return NO_SPECULATION;
 101         }
 102         SpeculationReason reason = speculations.get(constant.asLong());
 103         assert reason != null : "Speculation should have been registered";
 104         return new HotSpotSpeculation(reason, constant);
 105     }
 106 }