1 /*
   2  * Copyright (c) 2012, 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.meta;
  24 



  25 /**
  26  * Manages unique deoptimization reasons. Reasons are embedded in compiled code and can be
  27  * invalidated at run time. Subsequent compilations then should not speculate again on such
  28  * invalidated reasons to avoid repeated deoptimization.
  29  *
  30  * All methods of this interface are called by the compiler. There is no need for API to register
  31  * failed speculations during deoptimization, since every VM has different needs there.
  32  */
  33 public interface SpeculationLog {
  34     /**
  35      * Marker interface for speculation objects that can be added to the speculation log.










  36      */
  37     public interface SpeculationReason {








































  38     }
  39 
  40     /**
  41      * Marker class that indicates that a speculation has no reason.
  42      */
  43     final class NoSpeculationReason implements SpeculationReason {
  44     }
  45 
  46     class Speculation {
  47         private SpeculationReason reason;
  48 
  49         public Speculation(SpeculationReason reason) {
  50             this.reason = reason;
  51         }
  52 
  53         public SpeculationReason getReason() {
  54             return reason;
  55         }
  56 
  57         @Override
  58         public String toString() {
  59             return reason.toString();
  60         }
  61 
  62         @Override
  63         public boolean equals(Object obj) {
  64             if (obj instanceof Speculation) {
  65                 Speculation other = (Speculation) obj;
  66                 return reason.equals(other.reason);
  67             }
  68             return false;
  69         }
  70 
  71         @Override
  72         public int hashCode() {
  73             return getReason().hashCode();
  74         }
  75     }
  76 
  77     Speculation NO_SPECULATION = new Speculation(new NoSpeculationReason());
  78 
  79     /**
  80      * Must be called before compilation, i.e., before a compiler calls {@link #maySpeculate}.

  81      */
  82     void collectFailedSpeculations();
  83 
  84     /**
  85      * If this method returns true, the compiler is allowed to {@link #speculate} with the given
  86      * reason.
  87      */
  88     boolean maySpeculate(SpeculationReason reason);
  89 
  90     /**
  91      * Registers a speculation performed by the compiler. The compiler must guard every call to this
  92      * method for a specific reason with a call to {@link #maySpeculate(SpeculationReason)}.
  93      *
  94      * This API is subject to a benign race where a during the course of a compilation another
  95      * thread might fail a speculation such that {@link #maySpeculate(SpeculationReason)} will
  96      * return false but an earlier call returned true. This method will still return a working
  97      * {@link Speculation} in that case but the compile will eventually be invalidated and the
  98      * compile attempted again without the now invalid speculation.
  99      *
 100      * @param reason an object representing the reason for the speculation

   1 /*
   2  * Copyright (c) 2012, 2019, 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.meta;
  24 
  25 import java.util.Map;
  26 import java.util.function.Supplier;
  27 
  28 /**
  29  * Manages unique {@link SpeculationReason} objects that denote why a deoptimization occurred.
  30  * Reasons are embedded in compiled code for a method. If the compiled code deoptimizes at a
  31  * position associated with a {@link SpeculationReason}, the reason is added to a set of failed
  32  * speculations associated with the method. A subsequent compilation of the method can query the
  33  * failed speculations via a {@link SpeculationLog} to avoid making a speculation based on
  34  * invalidated reasons. This avoids repeated deoptimizations.
  35  */
  36 public interface SpeculationLog {
  37     /**
  38      * The specific attributes of a speculation that a compiler uses to denote a speculation in a
  39      * compiled method. Typical attributes of a speculation are a bytecode position, type
  40      * information about a variable being speculated on and an enum denoting the type of operation
  41      * to which the speculation applies. A {@link SpeculationReason} is used as a key in a
  42      * {@link Map} and so it must implement {@link Object#equals(Object)} and
  43      * {@link Object#hashCode()} in terms of its attributes.
  44      *
  45      * A JVMCI implementation may serialize speculations for storage off heap (e.g. in native memory
  46      * associated with an nmethod). For this reason, the attributes of a {@link SpeculationReason}
  47      * are restricted to those supported by the {@code add...} methods of
  48      * {@link SpeculationReasonEncoding}.
  49      */
  50     public interface SpeculationReason {
  51 
  52         /**
  53          * Encodes the attributes of this reason using a {@link SpeculationReasonEncoding}. For
  54          * efficiency, a {@link SpeculationReason} implementation should cache the returned value
  55          * and return it for all subsequent calls to this method. This also underlines the
  56          * requirement that the encoding for a specific reason instance should be stable.
  57          *
  58          * @param encodingSupplier source of a {@link SpeculationReasonEncoding}
  59          * @return a {@link SpeculationReasonEncoding} that encodes all the attributes that uniquely
  60          *         identify this reason
  61          */
  62         default SpeculationReasonEncoding encode(Supplier<SpeculationReasonEncoding> encodingSupplier) {
  63             return null;
  64         }
  65     }
  66 
  67     /**
  68      * Provides a facility for encoding the attributes of a {@link SpeculationReason}. The encoding
  69      * format is determined by the implementation of this interface.
  70      */
  71     public interface SpeculationReasonEncoding {
  72         void addByte(int value);
  73 
  74         void addShort(int value);
  75 
  76         void addInt(int value);
  77 
  78         void addLong(long value);
  79 
  80         void addMethod(ResolvedJavaMethod method);
  81 
  82         void addType(ResolvedJavaType type);
  83 
  84         void addString(String value);
  85 
  86         default void addField(ResolvedJavaField field) {
  87             addType(field.getDeclaringClass());
  88             addInt(field.getModifiers());
  89             addInt(field.getOffset());
  90         }
  91     }
  92 
  93     /**
  94      * Marker class that indicates that a speculation has no reason.
  95      */
  96     final class NoSpeculationReason implements SpeculationReason {
  97     }
  98 
  99     class Speculation {
 100         private final SpeculationReason reason;
 101 
 102         public Speculation(SpeculationReason reason) {
 103             this.reason = reason;
 104         }
 105 
 106         public SpeculationReason getReason() {
 107             return reason;
 108         }
 109 
 110         @Override
 111         public String toString() {
 112             return reason.toString();
 113         }
 114 
 115         @Override
 116         public boolean equals(Object obj) {
 117             if (obj instanceof Speculation) {
 118                 Speculation other = (Speculation) obj;
 119                 return reason.equals(other.reason);
 120             }
 121             return false;
 122         }
 123 
 124         @Override
 125         public int hashCode() {
 126             return getReason().hashCode();
 127         }
 128     }
 129 
 130     Speculation NO_SPECULATION = new Speculation(new NoSpeculationReason());
 131 
 132     /**
 133      * Updates the set of failed speculations recorded in this log. This must be called before
 134      * compilation.
 135      */
 136     void collectFailedSpeculations();
 137 
 138     /**
 139      * If this method returns true, the compiler is allowed to {@link #speculate} with the given
 140      * reason.
 141      */
 142     boolean maySpeculate(SpeculationReason reason);
 143 
 144     /**
 145      * Registers a speculation performed by the compiler. The compiler must guard every call to this
 146      * method for a specific reason with a call to {@link #maySpeculate(SpeculationReason)}.
 147      *
 148      * This API is subject to a benign race where a during the course of a compilation another
 149      * thread might fail a speculation such that {@link #maySpeculate(SpeculationReason)} will
 150      * return false but an earlier call returned true. This method will still return a working
 151      * {@link Speculation} in that case but the compile will eventually be invalidated and the
 152      * compile attempted again without the now invalid speculation.
 153      *
 154      * @param reason an object representing the reason for the speculation