1 /*
   2  * Copyright (c) 2016, 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 org.graalvm.compiler.hotspot.meta;
  24 
  25 import static org.graalvm.compiler.core.common.GraalOptions.ImmutableCode;
  26 import static org.graalvm.compiler.hotspot.meta.HotSpotGraalConstantFieldProvider.ImmutableCodeLazy.isCalledForSnippets;
  27 import static org.graalvm.compiler.hotspot.stubs.SnippetStub.SnippetGraphUnderConstruction;
  28 
  29 import java.util.ArrayList;
  30 import java.util.List;
  31 
  32 import org.graalvm.compiler.debug.GraalError;
  33 import org.graalvm.compiler.graph.NodeClass;
  34 import org.graalvm.compiler.hotspot.GraalHotSpotVMConfig;
  35 import org.graalvm.compiler.options.StableOptionValue;
  36 import org.graalvm.compiler.replacements.ReplacementsImpl;
  37 import org.graalvm.compiler.replacements.SnippetCounter;
  38 import org.graalvm.compiler.replacements.SnippetTemplate;
  39 import org.graalvm.compiler.replacements.SnippetTemplate.Arguments;
  40 
  41 import jdk.vm.ci.meta.JavaConstant;
  42 import jdk.vm.ci.meta.MetaAccessProvider;
  43 import jdk.vm.ci.meta.ResolvedJavaField;
  44 import jdk.vm.ci.meta.ResolvedJavaMethod;
  45 import jdk.vm.ci.meta.ResolvedJavaType;
  46 import jdk.vm.ci.runtime.JVMCI;
  47 
  48 /**
  49  * Extends {@link HotSpotConstantFieldProvider} to override the implementation of
  50  * {@link #readConstantField} with Graal specific semantics.
  51  */
  52 public class HotSpotGraalConstantFieldProvider extends HotSpotConstantFieldProvider {
  53 
  54     public HotSpotGraalConstantFieldProvider(GraalHotSpotVMConfig config, MetaAccessProvider metaAccess) {
  55         super(config, metaAccess);
  56         this.metaAccess = metaAccess;
  57     }
  58 
  59     @Override
  60     public <T> T readConstantField(ResolvedJavaField field, ConstantFieldTool<T> tool) {
  61         assert !ImmutableCode.getValue() || isCalledForSnippets(metaAccess) || SnippetGraphUnderConstruction.get() != null ||
  62                         FieldReadEnabledInImmutableCode.get() == Boolean.TRUE : tool.getReceiver();
  63         if (!field.isStatic() && field.getName().equals("value")) {
  64             if (getStableOptionValueType().isInstance(tool.getReceiver())) {
  65                 JavaConstant ret = tool.readValue();
  66                 return tool.foldConstant(ret);
  67             }
  68         }
  69 
  70         return super.readConstantField(field, tool);
  71     }
  72 
  73     /**
  74      * In AOT mode, some fields should never be embedded even for snippets/replacements.
  75      */
  76     @Override
  77     protected boolean isStaticFieldConstant(ResolvedJavaField field) {
  78         return super.isStaticFieldConstant(field) && (!ImmutableCode.getValue() || ImmutableCodeLazy.isEmbeddable(field));
  79     }
  80 
  81     @Override
  82     protected boolean isFinalFieldValueConstant(ResolvedJavaField field, JavaConstant value, ConstantFieldTool<?> tool) {
  83         if (super.isFinalFieldValueConstant(field, value, tool)) {
  84             return true;
  85         }
  86 
  87         if (!field.isStatic()) {
  88             JavaConstant receiver = tool.getReceiver();
  89             if (getSnippetCounterType().isInstance(receiver) || getNodeClassType().isInstance(receiver)) {
  90                 return true;
  91             }
  92         }
  93 
  94         return false;
  95     }
  96 
  97     @Override
  98     protected boolean isStableFieldValueConstant(ResolvedJavaField field, JavaConstant value, ConstantFieldTool<?> tool) {
  99         if (super.isStableFieldValueConstant(field, value, tool)) {
 100             return true;
 101         }
 102 
 103         if (!field.isStatic()) {
 104             JavaConstant receiver = tool.getReceiver();
 105             if (getHotSpotVMConfigType().isInstance(receiver)) {
 106                 return true;
 107             }
 108         }
 109 
 110         return false;
 111     }
 112 
 113     private final MetaAccessProvider metaAccess;
 114 
 115     private ResolvedJavaType cachedStableOptionValueType;
 116     private ResolvedJavaType cachedHotSpotVMConfigType;
 117     private ResolvedJavaType cachedSnippetCounterType;
 118     private ResolvedJavaType cachedNodeClassType;
 119 
 120     private ResolvedJavaType getStableOptionValueType() {
 121         if (cachedStableOptionValueType == null) {
 122             cachedStableOptionValueType = metaAccess.lookupJavaType(StableOptionValue.class);
 123         }
 124         return cachedStableOptionValueType;
 125     }
 126 
 127     private ResolvedJavaType getHotSpotVMConfigType() {
 128         if (cachedHotSpotVMConfigType == null) {
 129             cachedHotSpotVMConfigType = metaAccess.lookupJavaType(GraalHotSpotVMConfig.class);
 130         }
 131         return cachedHotSpotVMConfigType;
 132     }
 133 
 134     private ResolvedJavaType getSnippetCounterType() {
 135         if (cachedSnippetCounterType == null) {
 136             cachedSnippetCounterType = metaAccess.lookupJavaType(SnippetCounter.class);
 137         }
 138         return cachedSnippetCounterType;
 139     }
 140 
 141     private ResolvedJavaType getNodeClassType() {
 142         if (cachedNodeClassType == null) {
 143             cachedNodeClassType = metaAccess.lookupJavaType(NodeClass.class);
 144         }
 145         return cachedNodeClassType;
 146     }
 147 
 148     @SuppressWarnings("all")
 149     private static boolean assertionsEnabled() {
 150         boolean enabled = false;
 151         assert enabled = true;
 152         return enabled;
 153     }
 154 
 155     public static final ThreadLocal<Boolean> FieldReadEnabledInImmutableCode = assertionsEnabled() ? new ThreadLocal<>() : null;
 156 
 157     /**
 158      * Compares two {@link StackTraceElement}s for equality, ignoring differences in
 159      * {@linkplain StackTraceElement#getLineNumber() line number}.
 160      */
 161     private static boolean equalsIgnoringLine(StackTraceElement left, StackTraceElement right) {
 162         return left.getClassName().equals(right.getClassName()) && left.getMethodName().equals(right.getMethodName()) && left.getFileName().equals(right.getFileName());
 163     }
 164 
 165     /**
 166      * Separate out the static initialization of {@linkplain #isEmbeddable(ResolvedJavaField)
 167      * embeddable fields} to eliminate cycles between clinit and other locks that could lead to
 168      * deadlock. Static code that doesn't call back into type or field machinery is probably ok but
 169      * anything else should be made lazy.
 170      */
 171     static class ImmutableCodeLazy {
 172 
 173         /**
 174          * If the compiler is configured for AOT mode, {@link #readConstantField} should be only
 175          * called for snippets or replacements.
 176          */
 177         static boolean isCalledForSnippets(MetaAccessProvider metaAccess) {
 178             assert ImmutableCode.getValue();
 179             ResolvedJavaMethod makeGraphMethod = null;
 180             ResolvedJavaMethod initMethod = null;
 181             try {
 182                 Class<?> rjm = ResolvedJavaMethod.class;
 183                 makeGraphMethod = metaAccess.lookupJavaMethod(ReplacementsImpl.class.getDeclaredMethod("makeGraph", rjm, Object[].class, rjm));
 184                 initMethod = metaAccess.lookupJavaMethod(SnippetTemplate.AbstractTemplates.class.getDeclaredMethod("template", Arguments.class));
 185             } catch (NoSuchMethodException | SecurityException e) {
 186                 throw new GraalError(e);
 187             }
 188             StackTraceElement makeGraphSTE = makeGraphMethod.asStackTraceElement(0);
 189             StackTraceElement initSTE = initMethod.asStackTraceElement(0);
 190 
 191             StackTraceElement[] stackTrace = new Exception().getStackTrace();
 192             for (StackTraceElement element : stackTrace) {
 193                 // Ignoring line numbers should not weaken this check too much while at
 194                 // the same time making it more robust against source code changes
 195                 if (equalsIgnoringLine(makeGraphSTE, element) || equalsIgnoringLine(initSTE, element)) {
 196                     return true;
 197                 }
 198             }
 199             return false;
 200         }
 201 
 202         /**
 203          * Determine if it's ok to embed the value of {@code field}.
 204          */
 205         static boolean isEmbeddable(ResolvedJavaField field) {
 206             assert ImmutableCode.getValue();
 207             return !embeddableFields.contains(field);
 208         }
 209 
 210         private static final List<ResolvedJavaField> embeddableFields = new ArrayList<>();
 211         static {
 212             try {
 213                 MetaAccessProvider metaAccess = JVMCI.getRuntime().getHostJVMCIBackend().getMetaAccess();
 214                 embeddableFields.add(metaAccess.lookupJavaField(Boolean.class.getDeclaredField("TRUE")));
 215                 embeddableFields.add(metaAccess.lookupJavaField(Boolean.class.getDeclaredField("FALSE")));
 216 
 217                 Class<?> characterCacheClass = Character.class.getDeclaredClasses()[0];
 218                 assert "java.lang.Character$CharacterCache".equals(characterCacheClass.getName());
 219                 embeddableFields.add(metaAccess.lookupJavaField(characterCacheClass.getDeclaredField("cache")));
 220 
 221                 Class<?> byteCacheClass = Byte.class.getDeclaredClasses()[0];
 222                 assert "java.lang.Byte$ByteCache".equals(byteCacheClass.getName());
 223                 embeddableFields.add(metaAccess.lookupJavaField(byteCacheClass.getDeclaredField("cache")));
 224 
 225                 Class<?> shortCacheClass = Short.class.getDeclaredClasses()[0];
 226                 assert "java.lang.Short$ShortCache".equals(shortCacheClass.getName());
 227                 embeddableFields.add(metaAccess.lookupJavaField(shortCacheClass.getDeclaredField("cache")));
 228 
 229                 Class<?> integerCacheClass = Integer.class.getDeclaredClasses()[0];
 230                 assert "java.lang.Integer$IntegerCache".equals(integerCacheClass.getName());
 231                 embeddableFields.add(metaAccess.lookupJavaField(integerCacheClass.getDeclaredField("cache")));
 232 
 233                 Class<?> longCacheClass = Long.class.getDeclaredClasses()[0];
 234                 assert "java.lang.Long$LongCache".equals(longCacheClass.getName());
 235                 embeddableFields.add(metaAccess.lookupJavaField(longCacheClass.getDeclaredField("cache")));
 236 
 237                 embeddableFields.add(metaAccess.lookupJavaField(Throwable.class.getDeclaredField("UNASSIGNED_STACK")));
 238                 embeddableFields.add(metaAccess.lookupJavaField(Throwable.class.getDeclaredField("SUPPRESSED_SENTINEL")));
 239             } catch (SecurityException | NoSuchFieldException e) {
 240                 throw new GraalError(e);
 241             }
 242         }
 243     }
 244 
 245 }