1 /*
   2  * Copyright (c) 2011, 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.virtual.phases.ea;
  24 
  25 import static org.graalvm.compiler.core.common.GraalOptions.ReadEliminationMaxLoopVisits;
  26 import static org.graalvm.compiler.nodes.NamedLocationIdentity.ARRAY_LENGTH_LOCATION;
  27 
  28 import java.util.EnumMap;
  29 import java.util.Iterator;
  30 import java.util.List;
  31 
  32 import org.graalvm.compiler.core.common.cfg.Loop;
  33 import org.graalvm.compiler.core.common.spi.ConstantFieldProvider;
  34 import org.graalvm.compiler.core.common.type.Stamp;
  35 import org.graalvm.compiler.graph.Node;
  36 import org.graalvm.compiler.nodes.AbstractBeginNode;
  37 import org.graalvm.compiler.nodes.FieldLocationIdentity;
  38 import org.graalvm.compiler.nodes.FixedNode;
  39 import org.graalvm.compiler.nodes.FixedWithNextNode;
  40 import org.graalvm.compiler.nodes.LoopBeginNode;
  41 import org.graalvm.compiler.nodes.LoopExitNode;
  42 import org.graalvm.compiler.nodes.NamedLocationIdentity;
  43 import org.graalvm.compiler.nodes.PhiNode;
  44 import org.graalvm.compiler.nodes.ProxyNode;
  45 import org.graalvm.compiler.nodes.StructuredGraph.ScheduleResult;
  46 import org.graalvm.compiler.nodes.ValueNode;
  47 import org.graalvm.compiler.nodes.ValueProxyNode;
  48 import org.graalvm.compiler.nodes.cfg.Block;
  49 import org.graalvm.compiler.nodes.extended.RawLoadNode;
  50 import org.graalvm.compiler.nodes.extended.RawStoreNode;
  51 import org.graalvm.compiler.nodes.extended.UnboxNode;
  52 import org.graalvm.compiler.nodes.java.ArrayLengthNode;
  53 import org.graalvm.compiler.nodes.java.LoadFieldNode;
  54 import org.graalvm.compiler.nodes.java.LoadIndexedNode;
  55 import org.graalvm.compiler.nodes.java.StoreFieldNode;
  56 import org.graalvm.compiler.nodes.java.StoreIndexedNode;
  57 import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
  58 import org.graalvm.compiler.nodes.spi.LoweringProvider;
  59 import org.graalvm.compiler.nodes.type.StampTool;
  60 import org.graalvm.compiler.nodes.util.GraphUtil;
  61 import org.graalvm.compiler.nodes.virtual.VirtualArrayNode;
  62 import org.graalvm.compiler.options.OptionValues;
  63 import org.graalvm.compiler.virtual.phases.ea.PEReadEliminationBlockState.ReadCacheEntry;
  64 import org.graalvm.util.EconomicMap;
  65 import org.graalvm.util.EconomicSet;
  66 import org.graalvm.util.Equivalence;
  67 import org.graalvm.util.MapCursor;
  68 import org.graalvm.util.Pair;
  69 import org.graalvm.word.LocationIdentity;
  70 
  71 import jdk.vm.ci.meta.ConstantReflectionProvider;
  72 import jdk.vm.ci.meta.JavaConstant;
  73 import jdk.vm.ci.meta.JavaKind;
  74 import jdk.vm.ci.meta.MetaAccessProvider;
  75 import jdk.vm.ci.meta.ResolvedJavaType;
  76 
  77 public final class PEReadEliminationClosure extends PartialEscapeClosure<PEReadEliminationBlockState> {
  78 
  79     private static final EnumMap<JavaKind, LocationIdentity> UNBOX_LOCATIONS;
  80 
  81     static {
  82         UNBOX_LOCATIONS = new EnumMap<>(JavaKind.class);
  83         for (JavaKind kind : JavaKind.values()) {
  84             UNBOX_LOCATIONS.put(kind, NamedLocationIdentity.immutable("PEA unbox " + kind.getJavaName()));
  85         }
  86     }
  87 
  88     public PEReadEliminationClosure(ScheduleResult schedule, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection, ConstantFieldProvider constantFieldProvider,
  89                     LoweringProvider loweringProvider) {
  90         super(schedule, metaAccess, constantReflection, constantFieldProvider, loweringProvider);
  91     }
  92 
  93     @Override
  94     protected PEReadEliminationBlockState getInitialState() {
  95         return new PEReadEliminationBlockState(tool.getOptions(), tool.getDebug());
  96     }
  97 
  98     @Override
  99     protected boolean processNode(Node node, PEReadEliminationBlockState state, GraphEffectList effects, FixedWithNextNode lastFixedNode) {
 100         if (super.processNode(node, state, effects, lastFixedNode)) {
 101             return true;
 102         }
 103 
 104         if (node instanceof LoadFieldNode) {
 105             return processLoadField((LoadFieldNode) node, state, effects);
 106         } else if (node instanceof StoreFieldNode) {
 107             return processStoreField((StoreFieldNode) node, state, effects);
 108         } else if (node instanceof LoadIndexedNode) {
 109             return processLoadIndexed((LoadIndexedNode) node, state, effects);
 110         } else if (node instanceof StoreIndexedNode) {
 111             return processStoreIndexed((StoreIndexedNode) node, state, effects);
 112         } else if (node instanceof ArrayLengthNode) {
 113             return processArrayLength((ArrayLengthNode) node, state, effects);
 114         } else if (node instanceof UnboxNode) {
 115             return processUnbox((UnboxNode) node, state, effects);
 116         } else if (node instanceof RawLoadNode) {
 117             return processUnsafeLoad((RawLoadNode) node, state, effects);
 118         } else if (node instanceof RawStoreNode) {
 119             return processUnsafeStore((RawStoreNode) node, state, effects);
 120         } else if (node instanceof MemoryCheckpoint.Single) {
 121             COUNTER_MEMORYCHECKPOINT.increment(node.getDebug());
 122             LocationIdentity identity = ((MemoryCheckpoint.Single) node).getLocationIdentity();
 123             processIdentity(state, identity);
 124         } else if (node instanceof MemoryCheckpoint.Multi) {
 125             COUNTER_MEMORYCHECKPOINT.increment(node.getDebug());
 126             for (LocationIdentity identity : ((MemoryCheckpoint.Multi) node).getLocationIdentities()) {
 127                 processIdentity(state, identity);
 128             }
 129         }
 130 
 131         return false;
 132     }
 133 
 134     private boolean processStore(FixedNode store, ValueNode object, LocationIdentity identity, int index, JavaKind kind, ValueNode value, PEReadEliminationBlockState state, GraphEffectList effects) {

 135         ValueNode unproxiedObject = GraphUtil.unproxify(object);
 136         ValueNode cachedValue = state.getReadCache(object, identity, index, kind, this);
 137 
 138         ValueNode finalValue = getScalarAlias(value);
 139         boolean result = false;
 140         if (GraphUtil.unproxify(finalValue) == GraphUtil.unproxify(cachedValue)) {
 141             effects.deleteNode(store);
 142             result = true;
 143         }
 144         state.killReadCache(identity, index);
 145         state.addReadCache(unproxiedObject, identity, index, kind, finalValue, this);
 146         return result;
 147     }
 148 
 149     private boolean processLoad(FixedNode load, ValueNode object, LocationIdentity identity, int index, JavaKind kind, PEReadEliminationBlockState state, GraphEffectList effects) {
 150         ValueNode unproxiedObject = GraphUtil.unproxify(object);
 151         ValueNode cachedValue = state.getReadCache(unproxiedObject, identity, index, kind, this);
 152         if (cachedValue != null) {
 153             Stamp loadStamp = load.stamp();
 154             Stamp cachedValueStamp = cachedValue.stamp();
 155             if (!loadStamp.isCompatible(cachedValueStamp)) {
 156                 /*
 157                  * Can either be the first field of a two slot write to a one slot field which would
 158                  * have a non compatible stamp or the second load which will see Illegal.
 159                  */
 160                 assert load.stamp().getStackKind() == JavaKind.Int && (cachedValue.stamp().getStackKind() == JavaKind.Long || cachedValue.getStackKind() == JavaKind.Double ||
 161                                 cachedValue.getStackKind() == JavaKind.Illegal) : "Can only allow different stack kind two slot marker writes on one slot fields.";
 162                 return false;
 163             } else {
 164                 // perform the read elimination
 165                 effects.replaceAtUsages(load, cachedValue, load);
 166                 addScalarAlias(load, cachedValue);
 167                 return true;
 168             }
 169         } else {
 170             state.addReadCache(unproxiedObject, identity, index, kind, load, this);
 171             return false;
 172         }
 173     }
 174 


















 175     private boolean processUnsafeLoad(RawLoadNode load, PEReadEliminationBlockState state, GraphEffectList effects) {
 176         if (load.offset().isConstant()) {
 177             ResolvedJavaType type = StampTool.typeOrNull(load.object());
 178             if (type != null && type.isArray()) {


 179                 long offset = load.offset().asJavaConstant().asLong();
 180                 int index = VirtualArrayNode.entryIndexForOffset(offset, load.accessKind(), type.getComponentType(), Integer.MAX_VALUE);
 181                 ValueNode object = GraphUtil.unproxify(load.object());
 182                 LocationIdentity location = NamedLocationIdentity.getArrayLocation(type.getComponentType().getJavaKind());
 183                 ValueNode cachedValue = state.getReadCache(object, location, index, load.accessKind(), this);
 184                 if (cachedValue != null && load.stamp().isCompatible(cachedValue.stamp())) {

 185                     effects.replaceAtUsages(load, cachedValue, load);
 186                     addScalarAlias(load, cachedValue);
 187                     return true;
 188                 } else {
 189                     state.addReadCache(object, location, index, load.accessKind(), load, this);
 190                 }
 191             }
 192         }
 193         return false;
 194     }
 195 
 196     private boolean processUnsafeStore(RawStoreNode store, PEReadEliminationBlockState state, GraphEffectList effects) {
 197         ResolvedJavaType type = StampTool.typeOrNull(store.object());
 198         if (type != null && type.isArray()) {
 199             LocationIdentity location = NamedLocationIdentity.getArrayLocation(type.getComponentType().getJavaKind());


 200             if (store.offset().isConstant()) {
 201                 long offset = store.offset().asJavaConstant().asLong();
 202                 int index = VirtualArrayNode.entryIndexForOffset(offset, store.accessKind(), type.getComponentType(), Integer.MAX_VALUE);
 203                 return processStore(store, store.object(), location, index, store.accessKind(), store.value(), state, effects);

 204             } else {
 205                 processIdentity(state, location);
 206             }
 207         } else {
 208             state.killReadCache();
 209         }
 210         return false;
 211     }
 212 
 213     private boolean processArrayLength(ArrayLengthNode length, PEReadEliminationBlockState state, GraphEffectList effects) {
 214         return processLoad(length, length.array(), ARRAY_LENGTH_LOCATION, -1, JavaKind.Int, state, effects);
 215     }
 216 
 217     private boolean processStoreField(StoreFieldNode store, PEReadEliminationBlockState state, GraphEffectList effects) {
 218         if (store.isVolatile()) {
 219             state.killReadCache();
 220             return false;
 221         }
 222         return processStore(store, store.object(), new FieldLocationIdentity(store.field()), -1, store.field().getJavaKind(), store.value(), state, effects);

 223     }
 224 
 225     private boolean processLoadField(LoadFieldNode load, PEReadEliminationBlockState state, GraphEffectList effects) {
 226         if (load.isVolatile()) {
 227             state.killReadCache();
 228             return false;
 229         }
 230         return processLoad(load, load.object(), new FieldLocationIdentity(load.field()), -1, load.field().getJavaKind(), state, effects);
 231     }
 232 










 233     private boolean processStoreIndexed(StoreIndexedNode store, PEReadEliminationBlockState state, GraphEffectList effects) {
 234         LocationIdentity arrayLocation = NamedLocationIdentity.getArrayLocation(store.elementKind());
 235         if (store.index().isConstant()) {
 236             int index = ((JavaConstant) store.index().asConstant()).asInt();
 237             return processStore(store, store.array(), arrayLocation, index, store.elementKind(), store.value(), state, effects);











 238         } else {
 239             state.killReadCache(arrayLocation, -1);
 240         }
 241         return false;
 242     }
 243 
 244     private boolean processLoadIndexed(LoadIndexedNode load, PEReadEliminationBlockState state, GraphEffectList effects) {
 245         if (load.index().isConstant()) {
 246             int index = ((JavaConstant) load.index().asConstant()).asInt();
 247             LocationIdentity arrayLocation = NamedLocationIdentity.getArrayLocation(load.elementKind());
 248             return processLoad(load, load.array(), arrayLocation, index, load.elementKind(), state, effects);









 249         }
 250         return false;
 251     }
 252 
 253     private boolean processUnbox(UnboxNode unbox, PEReadEliminationBlockState state, GraphEffectList effects) {
 254         return processLoad(unbox, unbox.getValue(), UNBOX_LOCATIONS.get(unbox.getBoxingKind()), -1, unbox.getBoxingKind(), state, effects);
 255     }
 256 
 257     private static void processIdentity(PEReadEliminationBlockState state, LocationIdentity identity) {
 258         if (identity.isAny()) {
 259             state.killReadCache();
 260         } else {
 261             state.killReadCache(identity, -1);
 262         }
 263     }
 264 
 265     @SuppressWarnings("unchecked")
 266     @Override
 267     protected void processInitialLoopState(Loop<Block> loop, PEReadEliminationBlockState initialState) {
 268         super.processInitialLoopState(loop, initialState);
 269 
 270         if (!initialState.getReadCache().isEmpty()) {
 271             EconomicMap<ValueNode, Pair<ValueNode, Object>> firstValueSet = null;
 272             for (PhiNode phi : ((LoopBeginNode) loop.getHeader().getBeginNode()).phis()) {
 273                 ValueNode firstValue = phi.valueAt(0);
 274                 if (firstValue != null && phi.getStackKind().isObject()) {
 275                     ValueNode unproxified = GraphUtil.unproxify(firstValue);
 276                     if (firstValueSet == null) {
 277                         firstValueSet = EconomicMap.create(Equivalence.IDENTITY_WITH_SYSTEM_HASHCODE);
 278                     }
 279                     Pair<ValueNode, Object> pair = Pair.create(unproxified, firstValueSet.get(unproxified));
 280                     firstValueSet.put(unproxified, pair);
 281                 }
 282             }
 283 
 284             if (firstValueSet != null) {
 285                 ReadCacheEntry[] entries = new ReadCacheEntry[initialState.getReadCache().size()];
 286                 int z = 0;
 287                 for (ReadCacheEntry entry : initialState.getReadCache().getKeys()) {
 288                     entries[z++] = entry;
 289                 }
 290 
 291                 for (ReadCacheEntry entry : entries) {
 292                     ValueNode object = entry.object;
 293                     if (object != null) {
 294                         Pair<ValueNode, Object> pair = firstValueSet.get(object);
 295                         while (pair != null) {
 296                             initialState.addReadCache(pair.getLeft(), entry.identity, entry.index, entry.kind, initialState.getReadCache().get(entry), this);
 297                             pair = (Pair<ValueNode, Object>) pair.getRight();
 298                         }
 299                     }
 300                 }
 301             }
 302         }
 303     }
 304 
 305     @Override
 306     protected void processLoopExit(LoopExitNode exitNode, PEReadEliminationBlockState initialState, PEReadEliminationBlockState exitState, GraphEffectList effects) {
 307         super.processLoopExit(exitNode, initialState, exitState, effects);
 308 
 309         if (exitNode.graph().hasValueProxies()) {
 310             MapCursor<ReadCacheEntry, ValueNode> entry = exitState.getReadCache().getEntries();
 311             while (entry.advance()) {
 312                 if (initialState.getReadCache().get(entry.getKey()) != entry.getValue()) {
 313                     ValueNode value = exitState.getReadCache(entry.getKey().object, entry.getKey().identity, entry.getKey().index, entry.getKey().kind, this);
 314                     assert value != null : "Got null from read cache, entry's value:" + entry.getValue();
 315                     if (!(value instanceof ProxyNode) || ((ProxyNode) value).proxyPoint() != exitNode) {
 316                         ProxyNode proxy = new ValueProxyNode(value, exitNode);
 317                         effects.addFloatingNode(proxy, "readCacheProxy");
 318                         exitState.getReadCache().put(entry.getKey(), proxy);
 319                     }
 320                 }
 321             }
 322         }
 323     }
 324 
 325     @Override
 326     protected PEReadEliminationBlockState cloneState(PEReadEliminationBlockState other) {
 327         return new PEReadEliminationBlockState(other);
 328     }
 329 
 330     @Override
 331     protected MergeProcessor createMergeProcessor(Block merge) {
 332         return new ReadEliminationMergeProcessor(merge);
 333     }
 334 
 335     private class ReadEliminationMergeProcessor extends MergeProcessor {
 336 
 337         ReadEliminationMergeProcessor(Block mergeBlock) {
 338             super(mergeBlock);
 339         }
 340 
 341         @Override
 342         protected void merge(List<PEReadEliminationBlockState> states) {
 343             super.merge(states);
 344 
 345             mergeReadCache(states);
 346         }
 347 
 348         private void mergeReadCache(List<PEReadEliminationBlockState> states) {
 349             MapCursor<ReadCacheEntry, ValueNode> cursor = states.get(0).readCache.getEntries();
 350             while (cursor.advance()) {
 351                 ReadCacheEntry key = cursor.getKey();
 352                 ValueNode value = cursor.getValue();
 353                 boolean phi = false;
 354                 for (int i = 1; i < states.size(); i++) {
 355                     ValueNode otherValue = states.get(i).readCache.get(key);
 356                     // e.g. unsafe loads / stores with different access kinds have different stamps
 357                     // although location, object and offset are the same, in this case we cannot
 358                     // create a phi nor can we set a common value
 359                     if (otherValue == null || !value.stamp().isCompatible(otherValue.stamp())) {
 360                         value = null;
 361                         phi = false;
 362                         break;
 363                     }
 364                     if (!phi && otherValue != value) {
 365                         phi = true;
 366                     }
 367                 }
 368                 if (phi) {
 369                     PhiNode phiNode = getPhi(key, value.stamp().unrestricted());
 370                     mergeEffects.addFloatingNode(phiNode, "mergeReadCache");
 371                     for (int i = 0; i < states.size(); i++) {
 372                         ValueNode v = states.get(i).getReadCache(key.object, key.identity, key.index, key.kind, PEReadEliminationClosure.this);
 373                         assert phiNode.stamp().isCompatible(v.stamp()) : "Cannot create read elimination phi for inputs with incompatible stamps.";
 374                         setPhiInput(phiNode, i, v);
 375                     }
 376                     newState.readCache.put(key, phiNode);
 377                 } else if (value != null) {
 378                     newState.readCache.put(key, value);
 379                 }
 380             }
 381             /*
 382              * For object phis, see if there are known reads on all predecessors, for which we could
 383              * create new phis.
 384              */
 385             for (PhiNode phi : getPhis()) {
 386                 if (phi.getStackKind() == JavaKind.Object) {
 387                     for (ReadCacheEntry entry : states.get(0).readCache.getKeys()) {
 388                         if (entry.object == getPhiValueAt(phi, 0)) {
 389                             mergeReadCachePhi(phi, entry.identity, entry.index, entry.kind, states);
 390                         }
 391                     }
 392                 }
 393             }
 394         }
 395 
 396         private void mergeReadCachePhi(PhiNode phi, LocationIdentity identity, int index, JavaKind kind, List<PEReadEliminationBlockState> states) {
 397             ValueNode[] values = new ValueNode[states.size()];
 398             values[0] = states.get(0).getReadCache(getPhiValueAt(phi, 0), identity, index, kind, PEReadEliminationClosure.this);
 399             if (values[0] != null) {
 400                 for (int i = 1; i < states.size(); i++) {
 401                     ValueNode value = states.get(i).getReadCache(getPhiValueAt(phi, i), identity, index, kind, PEReadEliminationClosure.this);
 402                     // e.g. unsafe loads / stores with same identity and different access kinds see
 403                     // mergeReadCache(states)
 404                     if (value == null || !values[i - 1].stamp().isCompatible(value.stamp())) {
 405                         return;
 406                     }
 407                     values[i] = value;
 408                 }
 409 
 410                 PhiNode phiNode = getPhi(new ReadCacheEntry(identity, phi, index, kind), values[0].stamp().unrestricted());
 411                 mergeEffects.addFloatingNode(phiNode, "mergeReadCachePhi");
 412                 for (int i = 0; i < values.length; i++) {
 413                     setPhiInput(phiNode, i, values[i]);
 414                 }
 415                 newState.readCache.put(new ReadCacheEntry(identity, phi, index, kind), phiNode);
 416             }
 417         }
 418     }
 419 
 420     @Override
 421     protected void processKilledLoopLocations(Loop<Block> loop, PEReadEliminationBlockState initialState, PEReadEliminationBlockState mergedStates) {
 422         assert initialState != null;
 423         assert mergedStates != null;
 424         if (initialState.readCache.size() > 0) {
 425             LoopKillCache loopKilledLocations = loopLocationKillCache.get(loop);
 426             // we have fully processed this loop the first time, remember to cache it the next time
 427             // it is visited
 428             if (loopKilledLocations == null) {
 429                 loopKilledLocations = new LoopKillCache(1/* 1.visit */);
 430                 loopLocationKillCache.put(loop, loopKilledLocations);
 431             } else {
 432                 AbstractBeginNode beginNode = loop.getHeader().getBeginNode();
 433                 OptionValues options = beginNode.getOptions();
 434                 if (loopKilledLocations.visits() > ReadEliminationMaxLoopVisits.getValue(options)) {
 435                     // we have processed the loop too many times, kill all locations so the inner
 436                     // loop will never be processed more than once again on visit
 437                     loopKilledLocations.setKillsAll();
 438                 } else {
 439                     // we have fully processed this loop >1 times, update the killed locations
 440                     EconomicSet<LocationIdentity> forwardEndLiveLocations = EconomicSet.create(Equivalence.DEFAULT);
 441                     for (ReadCacheEntry entry : initialState.readCache.getKeys()) {
 442                         forwardEndLiveLocations.add(entry.identity);
 443                     }
 444                     for (ReadCacheEntry entry : mergedStates.readCache.getKeys()) {
 445                         forwardEndLiveLocations.remove(entry.identity);
 446                     }
 447                     // every location that is alive before the loop but not after is killed by the
 448                     // loop
 449                     for (LocationIdentity location : forwardEndLiveLocations) {
 450                         loopKilledLocations.rememberLoopKilledLocation(location);
 451                     }
 452                     if (debug.isLogEnabled() && loopKilledLocations != null) {
 453                         debug.log("[Early Read Elimination] Setting loop killed locations of loop at node %s with %s",
 454                                         beginNode, forwardEndLiveLocations);
 455                     }
 456                 }
 457                 // remember the loop visit
 458                 loopKilledLocations.visited();
 459             }
 460         }
 461     }
 462 
 463     @Override
 464     protected PEReadEliminationBlockState stripKilledLoopLocations(Loop<Block> loop, PEReadEliminationBlockState originalInitialState) {
 465         PEReadEliminationBlockState initialState = super.stripKilledLoopLocations(loop, originalInitialState);
 466         LoopKillCache loopKilledLocations = loopLocationKillCache.get(loop);
 467         if (loopKilledLocations != null && loopKilledLocations.loopKillsLocations()) {
 468             Iterator<ReadCacheEntry> it = initialState.readCache.getKeys().iterator();
 469             while (it.hasNext()) {
 470                 ReadCacheEntry entry = it.next();
 471                 if (loopKilledLocations.containsLocation(entry.identity)) {
 472                     it.remove();
 473                 }
 474             }
 475         }
 476         return initialState;
 477     }
 478 
 479 }
--- EOF ---