Robust/src/Analysis/Locality/DiscoverConflicts.java

   1 package Analysis.Locality;
   2
   3 import IR.Flat.*;
   4 import java.util.Set;
   5 import java.util.Arrays;
   6 import java.util.HashSet;
   7 import java.util.Iterator;
   8 import java.util.Hashtable;
   9 import IR.State;
  10 import IR.Operation;
  11 import IR.TypeDescriptor;
  12 import IR.MethodDescriptor;
  13 import IR.FieldDescriptor;
  14
  15 public class DiscoverConflicts {
  16   Set<FieldDescriptor> fields;
  17   Set<TypeDescriptor> arrays;
  18   LocalityAnalysis locality;
  19   State state;
  20   Hashtable<LocalityBinding, Set<FlatNode>> treadmap;
  21   Hashtable<LocalityBinding, Set<TempFlatPair>> transreadmap;
  22   Hashtable<LocalityBinding, Set<FlatNode>> srcmap;
  23   Hashtable<LocalityBinding, Set<FlatNode>> leftsrcmap;
  24   Hashtable<LocalityBinding, Set<FlatNode>> rightsrcmap;
  25   TypeAnalysis typeanalysis;
  26   HashSet<FlatNode>cannotdelay;
  27   Hashtable<LocalityBinding, Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>>> lbtofnmap;
  28
  29
  30   public DiscoverConflicts(LocalityAnalysis locality, State state, TypeAnalysis typeanalysis) {
  31     this.locality=locality;
  32     this.fields=new HashSet<FieldDescriptor>();
  33     this.arrays=new HashSet<TypeDescriptor>();
  34     this.state=state;
  35     this.typeanalysis=typeanalysis;
  36     transreadmap=new Hashtable<LocalityBinding, Set<TempFlatPair>>();
  37     treadmap=new Hashtable<LocalityBinding, Set<FlatNode>>();
  38     srcmap=new Hashtable<LocalityBinding, Set<FlatNode>>();
  39     leftsrcmap=new Hashtable<LocalityBinding, Set<FlatNode>>();
  40     rightsrcmap=new Hashtable<LocalityBinding, Set<FlatNode>>();
  41     lbtofnmap=new Hashtable<LocalityBinding, Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>>>();
  42   }
  43
  44   public DiscoverConflicts(LocalityAnalysis locality, State state, TypeAnalysis typeanalysis, HashSet<FlatNode> cannotdelay) {
  45     this.locality=locality;
  46     this.fields=new HashSet<FieldDescriptor>();
  47     this.arrays=new HashSet<TypeDescriptor>();
  48     this.state=state;
  49     this.typeanalysis=typeanalysis;
  50     this.cannotdelay=cannotdelay;
  51     transreadmap=new Hashtable<LocalityBinding, Set<TempFlatPair>>();
  52     treadmap=new Hashtable<LocalityBinding, Set<FlatNode>>();
  53     srcmap=new Hashtable<LocalityBinding, Set<FlatNode>>();
  54     leftsrcmap=new Hashtable<LocalityBinding, Set<FlatNode>>();
  55     rightsrcmap=new Hashtable<LocalityBinding, Set<FlatNode>>();
  56     lbtofnmap=new Hashtable<LocalityBinding, Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>>>();
  57   }
  58
  59   public Set<FieldDescriptor> getFields() {
  60     return fields;
  61   }
  62
  63   public Set<TypeDescriptor> getArrays() {
  64     return arrays;
  65   }
  66
  67   public void doAnalysis() {
  68     //Compute fields and arrays for all transactions.  Note that we
  69     //only look at changes to old objects
  70
  71     Set<LocalityBinding> localityset=locality.getLocalityBindings();
  72     for(Iterator<LocalityBinding> lb=localityset.iterator();lb.hasNext();) {
  73       computeModified(lb.next());
  74     }
  75     expandTypes();
  76     //Compute set of nodes that need transread
  77     for(Iterator<LocalityBinding> lb=localityset.iterator();lb.hasNext();) {
  78       LocalityBinding l=lb.next();
  79       analyzeLocality(l);
  80       setNeedReadTrans(l);
  81     }
  82   }
  83
  84   //Change flatnode/temp pairs to just flatnodes that need transactional reads
  85
  86   public void setNeedReadTrans(LocalityBinding lb) {
  87     HashSet<FlatNode> set=new HashSet<FlatNode>();
  88     for(Iterator<TempFlatPair> it=transreadmap.get(lb).iterator();it.hasNext();) {
  89       TempFlatPair tfp=it.next();
  90       set.add(tfp.f);
  91     }
  92     treadmap.put(lb, set);
  93   }
  94
  95   //We have a set of things we write to, figure out what things this
  96   //could effect.
  97   public void expandTypes() {
  98     Set<TypeDescriptor> expandedarrays=new HashSet<TypeDescriptor>();
  99     for(Iterator<TypeDescriptor> it=arrays.iterator();it.hasNext();) {
 100       TypeDescriptor td=it.next();
 101       expandedarrays.addAll(typeanalysis.expand(td));
 102     }
 103     arrays=expandedarrays;
 104   }
 105
 106   Hashtable<TempDescriptor, Set<TempFlatPair>> doMerge(FlatNode fn, Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>> tmptofnset) {
 107     Hashtable<TempDescriptor, Set<TempFlatPair>> table=new Hashtable<TempDescriptor, Set<TempFlatPair>>();
 108     for(int i=0;i<fn.numPrev();i++) {
 109       FlatNode fprev=fn.getPrev(i);
 110       Hashtable<TempDescriptor, Set<TempFlatPair>> tabset=tmptofnset.get(fprev);
 111       if (tabset!=null) {
 112         for(Iterator<TempDescriptor> tmpit=tabset.keySet().iterator();tmpit.hasNext();) {
 113           TempDescriptor td=tmpit.next();
 114           Set<TempFlatPair> fnset=tabset.get(td);
 115           if (!table.containsKey(td))
 116             table.put(td, new HashSet<TempFlatPair>());
 117           table.get(td).addAll(fnset);
 118         }
 119       }
 120     }
 121     return table;
 122   }
 123
 124   public Set<FlatNode> getNeedSrcTrans(LocalityBinding lb) {
 125     return srcmap.get(lb);
 126   }
 127
 128   public boolean getNeedSrcTrans(LocalityBinding lb, FlatNode fn) {
 129     return srcmap.get(lb).contains(fn);
 130   }
 131
 132   public boolean getNeedLeftSrcTrans(LocalityBinding lb, FlatNode fn) {
 133     return leftsrcmap.get(lb).contains(fn);
 134   }
 135
 136   public boolean getNeedRightSrcTrans(LocalityBinding lb, FlatNode fn) {
 137     return rightsrcmap.get(lb).contains(fn);
 138   }
 139
 140   public boolean getNeedTrans(LocalityBinding lb, FlatNode fn) {
 141     return treadmap.get(lb).contains(fn);
 142   }
 143
 144   public Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>> getMap(LocalityBinding lb) {
 145     return lbtofnmap.get(lb);
 146   }
 147
 148   private void analyzeLocality(LocalityBinding lb) {
 149     MethodDescriptor md=lb.getMethod();
 150     FlatMethod fm=state.getMethodFlat(md);
 151     Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>> fnmap=computeTempSets(lb);
 152     lbtofnmap.put(lb,fnmap);
 153     HashSet<TempFlatPair> tfset=computeTranslationSet(lb, fm, fnmap);
 154     HashSet<FlatNode> srctrans=new HashSet<FlatNode>();
 155     HashSet<FlatNode> leftsrctrans=new HashSet<FlatNode>();
 156     HashSet<FlatNode> rightsrctrans=new HashSet<FlatNode>();
 157     transreadmap.put(lb, tfset);
 158     srcmap.put(lb,srctrans);
 159     leftsrcmap.put(lb,leftsrctrans);
 160     rightsrcmap.put(lb,rightsrctrans);
 161
 162     //compute writes that need translation on source
 163
 164     for(Iterator<FlatNode> fnit=fm.getNodeSet().iterator();fnit.hasNext();) {
 165       FlatNode fn=fnit.next();
 166       Hashtable<FlatNode, Integer> atomictable=locality.getAtomic(lb);
 167       if (atomictable.get(fn).intValue()>0) {
 168         Hashtable<TempDescriptor, Set<TempFlatPair>> tmap=fnmap.get(fn);
 169         switch(fn.kind()) {
 170
 171           //We might need to translate arguments to pointer comparison
 172
 173         case FKind.FlatOpNode: {
 174           FlatOpNode fon=(FlatOpNode)fn;
 175           if (fon.getOp().getOp()==Operation.EQUAL||
 176               fon.getOp().getOp()==Operation.NOTEQUAL) {
 177             if (!fon.getLeft().getType().isPtr())
 178               break;
 179             Set<TempFlatPair> lefttfpset=tmap.get(fon.getLeft());
 180             Set<TempFlatPair> righttfpset=tmap.get(fon.getRight());
 181             //handle left operand
 182             if (lefttfpset!=null) {
 183               for(Iterator<TempFlatPair> tfpit=lefttfpset.iterator();tfpit.hasNext();) {
 184                 TempFlatPair tfp=tfpit.next();
 185                 if (tfset.contains(tfp)||outofscope(tfp)) {
 186                   leftsrctrans.add(fon);
 187                   break;
 188                 }
 189               }
 190             }
 191             //handle right operand
 192             if (righttfpset!=null) {
 193               for(Iterator<TempFlatPair> tfpit=righttfpset.iterator();tfpit.hasNext();) {
 194                 TempFlatPair tfp=tfpit.next();
 195                 if (tfset.contains(tfp)||outofscope(tfp)) {
 196                   rightsrctrans.add(fon);
 197                   break;
 198                 }
 199               }
 200             }
 201           }
 202           break;
 203         }
 204
 205         case FKind.FlatSetFieldNode: {
 206           //need to translate these if the value we read from may be a
 207           //shadow...  check this by seeing if any of the values we
 208           //may read are in the transread set or came from our caller
 209           //or a method we called
 210
 211           FlatSetFieldNode fsfn=(FlatSetFieldNode)fn;
 212           if (!fsfn.getField().getType().isPtr())
 213             break;
 214           Set<TempFlatPair> tfpset=tmap.get(fsfn.getSrc());
 215           if (tfpset!=null) {
 216             for(Iterator<TempFlatPair> tfpit=tfpset.iterator();tfpit.hasNext();) {
 217               TempFlatPair tfp=tfpit.next();
 218               if (tfset.contains(tfp)||outofscope(tfp)) {
 219                 srctrans.add(fsfn);
 220                 break;
 221               }
 222             }
 223           }
 224           break;
 225         }
 226         case FKind.FlatSetElementNode: {
 227           //need to translate these if the value we read from may be a
 228           //shadow...  check this by seeing if any of the values we
 229           //may read are in the transread set or came from our caller
 230           //or a method we called
 231
 232           FlatSetElementNode fsen=(FlatSetElementNode)fn;
 233           if (!fsen.getSrc().getType().isPtr())
 234             break;
 235           Set<TempFlatPair> tfpset=tmap.get(fsen.getSrc());
 236           if (tfpset!=null) {
 237             for(Iterator<TempFlatPair> tfpit=tfpset.iterator();tfpit.hasNext();) {
 238               TempFlatPair tfp=tfpit.next();
 239               if (tfset.contains(tfp)||outofscope(tfp)) {
 240                 srctrans.add(fsen);
 241                 break;
 242               }
 243             }
 244           }
 245           break;
 246         }
 247         default:
 248         }
 249       }
 250     }
 251   }
 252
 253   public boolean outofscope(TempFlatPair tfp) {
 254     FlatNode fn=tfp.f;
 255     return fn.kind()==FKind.FlatCall||fn.kind()==FKind.FlatMethod;
 256   }
 257
 258
 259   /** Need to figure out which nodes need a transread to make local
 260   copies.  Transread conceptually tracks conflicts.  This depends on
 261   what fields/elements are accessed We iterate over all flatnodes that
 262   access fields...If these accesses could conflict, we mark the source
 263   tempflat pair as needing a transread */
 264
 265   HashSet<TempFlatPair> computeTranslationSet(LocalityBinding lb, FlatMethod fm, Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>> fnmap) {
 266     HashSet<TempFlatPair> tfset=new HashSet<TempFlatPair>();
 267
 268     for(Iterator<FlatNode> fnit=fm.getNodeSet().iterator();fnit.hasNext();) {
 269       FlatNode fn=fnit.next();
 270       Hashtable<FlatNode, Integer> atomictable=locality.getAtomic(lb);
 271
 272       //Check whether this node matters for delayed computation
 273       if (cannotdelay!=null&&!cannotdelay.contains(fn))
 274         continue;
 275
 276       if (atomictable.get(fn).intValue()>0) {
 277         Hashtable<TempDescriptor, Set<TempFlatPair>> tmap=fnmap.get(fn);
 278         switch(fn.kind()) {
 279         case FKind.FlatElementNode: {
 280           FlatElementNode fen=(FlatElementNode)fn;
 281           if (arrays.contains(fen.getSrc().getType())) {
 282             //this could cause conflict...figure out conflict set
 283             Set<TempFlatPair> tfpset=tmap.get(fen.getSrc());
 284             if (tfpset!=null)
 285               tfset.addAll(tfpset);
 286           }
 287           break;
 288         }
 289         case FKind.FlatFieldNode: {
 290           FlatFieldNode ffn=(FlatFieldNode)fn;
 291           if (fields.contains(ffn.getField())) {
 292             //this could cause conflict...figure out conflict set
 293             Set<TempFlatPair> tfpset=tmap.get(ffn.getSrc());
 294             if (tfpset!=null)
 295               tfset.addAll(tfpset);
 296           }
 297           break;
 298         }
 299         case FKind.FlatSetFieldNode: {
 300           //definitely need to translate these
 301           FlatSetFieldNode fsfn=(FlatSetFieldNode)fn;
 302           Set<TempFlatPair> tfpset=tmap.get(fsfn.getDst());
 303           if (tfpset!=null)
 304             tfset.addAll(tfpset);
 305           break;
 306         }
 307         case FKind.FlatSetElementNode: {
 308           //definitely need to translate these
 309           FlatSetElementNode fsen=(FlatSetElementNode)fn;
 310           Set<TempFlatPair> tfpset=tmap.get(fsen.getDst());
 311           if (tfpset!=null)
 312             tfset.addAll(tfpset);
 313           break;
 314         }
 315         case FKind.FlatCall: //assume pessimistically that calls do bad things
 316         case FKind.FlatReturnNode: {
 317           TempDescriptor []readarray=fn.readsTemps();
 318           for(int i=0;i<readarray.length;i++) {
 319             TempDescriptor rtmp=readarray[i];
 320             Set<TempFlatPair> tfpset=tmap.get(rtmp);
 321             if (tfpset!=null)
 322               tfset.addAll(tfpset);
 323           }
 324           break;
 325         }
 326         default:
 327           //do nothing
 328         }
 329       }
 330     }
 331     return tfset;
 332   }
 333
 334
 335   //This method generates as output for each node
 336   //A map from from temps to a set of temp/flat pairs that the
 337   //original temp points to
 338   //A temp/flat pair gives the flatnode that the value was created at
 339   //and the original temp
 340
 341   Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>> computeTempSets(LocalityBinding lb) {
 342     Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>> tmptofnset=new Hashtable<FlatNode, Hashtable<TempDescriptor, Set<TempFlatPair>>>();
 343     HashSet<FlatNode> discovered=new HashSet<FlatNode>();
 344     HashSet<FlatNode> tovisit=new HashSet<FlatNode>();
 345     MethodDescriptor md=lb.getMethod();
 346     FlatMethod fm=state.getMethodFlat(md);
 347     Hashtable<FlatNode, Integer> atomictable=locality.getAtomic(lb);
 348     Hashtable<FlatNode, Set<TempDescriptor>> livetemps=locality.computeLiveTemps(fm);
 349     tovisit.add(fm);
 350     discovered.add(fm);
 351
 352     while(!tovisit.isEmpty()) {
 353       FlatNode fn=tovisit.iterator().next();
 354       tovisit.remove(fn);
 355       for(int i=0;i<fn.numNext();i++) {
 356         FlatNode fnext=fn.getNext(i);
 357         if (!discovered.contains(fnext)) {
 358           discovered.add(fnext);
 359           tovisit.add(fnext);
 360         }
 361       }
 362       Hashtable<TempDescriptor, Set<TempFlatPair>> ttofn=null;
 363       if (atomictable.get(fn).intValue()!=0) {
 364         if ((fn.numPrev()>0)&&atomictable.get(fn.getPrev(0)).intValue()==0) {
 365           //atomic node, start with new set
 366           ttofn=new Hashtable<TempDescriptor, Set<TempFlatPair>>();
 367         } else {
 368           ttofn=doMerge(fn, tmptofnset);
 369           switch(fn.kind()) {
 370           case FKind.FlatGlobalConvNode: {
 371             FlatGlobalConvNode fgcn=(FlatGlobalConvNode)fn;
 372             if (lb==fgcn.getLocality()&&
 373                 fgcn.getMakePtr()) {
 374               TempDescriptor[] writes=fn.writesTemps();
 375               for(int i=0;i<writes.length;i++) {
 376                 TempDescriptor wtmp=writes[i];
 377                 HashSet<TempFlatPair> set=new HashSet<TempFlatPair>();
 378                 set.add(new TempFlatPair(wtmp, fn));
 379                 ttofn.put(wtmp, set);
 380               }
 381             }
 382             break;
 383           }
 384           case FKind.FlatFieldNode:
 385           case FKind.FlatElementNode: {
 386             TempDescriptor[] writes=fn.writesTemps();
 387             for(int i=0;i<writes.length;i++) {
 388               TempDescriptor wtmp=writes[i];
 389               HashSet<TempFlatPair> set=new HashSet<TempFlatPair>();
 390               set.add(new TempFlatPair(wtmp, fn));
 391               ttofn.put(wtmp, set);
 392             }
 393             break;
 394           }
 395           case FKind.FlatCall:
 396           case FKind.FlatMethod: {
 397             TempDescriptor[] writes=fn.writesTemps();
 398             for(int i=0;i<writes.length;i++) {
 399               TempDescriptor wtmp=writes[i];
 400               HashSet<TempFlatPair> set=new HashSet<TempFlatPair>();
 401               set.add(new TempFlatPair(wtmp, fn));
 402               ttofn.put(wtmp, set);
 403             }
 404             break;
 405           }
 406           case FKind.FlatOpNode: {
 407             FlatOpNode fon=(FlatOpNode)fn;
 408             if (fon.getOp().getOp()==Operation.ASSIGN&&fon.getDest().getType().isPtr()&&
 409                 ttofn.containsKey(fon.getLeft())) {
 410               ttofn.put(fon.getDest(), new HashSet<TempFlatPair>(ttofn.get(fon.getLeft())));
 411               break;
 412             }
 413           }
 414           default:
 415             //Do kill computation
 416             TempDescriptor[] writes=fn.writesTemps();
 417             for(int i=0;i<writes.length;i++) {
 418               TempDescriptor wtmp=writes[i];
 419               ttofn.remove(writes[i]);
 420             }
 421           }
 422         }
 423         if (ttofn!=null) {
 424           if (!tmptofnset.containsKey(fn)||
 425               !tmptofnset.get(fn).equals(ttofn)) {
 426             //enqueue nodes to process
 427             tmptofnset.put(fn, ttofn);
 428             for(int i=0;i<fn.numNext();i++) {
 429               FlatNode fnext=fn.getNext(i);
 430               tovisit.add(fnext);
 431             }
 432           }
 433         }
 434       }
 435     }
 436     return tmptofnset;
 437   }
 438
 439   /* See what fields and arrays transactions might modify.  We only
 440    * look at changes to old objects. */
 441
 442   public void computeModified(LocalityBinding lb) {
 443     MethodDescriptor md=lb.getMethod();
 444     FlatMethod fm=state.getMethodFlat(md);
 445     Hashtable<FlatNode, Set<TempDescriptor>> oldtemps=computeOldTemps(lb);
 446     for(Iterator<FlatNode> fnit=fm.getNodeSet().iterator();fnit.hasNext();) {
 447       FlatNode fn=fnit.next();
 448       Hashtable<FlatNode, Integer> atomictable=locality.getAtomic(lb);
 449       if (atomictable.get(fn).intValue()>0) {
 450         switch (fn.kind()) {
 451         case FKind.FlatSetFieldNode:
 452           FlatSetFieldNode fsfn=(FlatSetFieldNode) fn;
 453           fields.add(fsfn.getField());
 454           break;
 455         case FKind.FlatSetElementNode:
 456           FlatSetElementNode fsen=(FlatSetElementNode) fn;
 457           arrays.add(fsen.getDst().getType());
 458           break;
 459         default:
 460         }
 461       }
 462     }
 463   }
 464
 465
 466   //Returns a table that maps a flatnode to a set of temporaries
 467   //This set of temporaries is old (meaning they may point to object
 468   //allocated before the beginning of the current transaction
 469
 470   Hashtable<FlatNode, Set<TempDescriptor>> computeOldTemps(LocalityBinding lb) {
 471     Hashtable<FlatNode, Set<TempDescriptor>> fntooldtmp=new Hashtable<FlatNode, Set<TempDescriptor>>();
 472     HashSet<FlatNode> discovered=new HashSet<FlatNode>();
 473     HashSet<FlatNode> tovisit=new HashSet<FlatNode>();
 474     MethodDescriptor md=lb.getMethod();
 475     FlatMethod fm=state.getMethodFlat(md);
 476     Hashtable<FlatNode, Integer> atomictable=locality.getAtomic(lb);
 477     Hashtable<FlatNode, Set<TempDescriptor>> livetemps=locality.computeLiveTemps(fm);
 478     tovisit.add(fm);
 479     discovered.add(fm);
 480
 481     while(!tovisit.isEmpty()) {
 482       FlatNode fn=tovisit.iterator().next();
 483       tovisit.remove(fn);
 484       for(int i=0;i<fn.numNext();i++) {
 485         FlatNode fnext=fn.getNext(i);
 486         if (!discovered.contains(fnext)) {
 487           discovered.add(fnext);
 488           tovisit.add(fnext);
 489         }
 490       }
 491       HashSet<TempDescriptor> oldtemps=null;
 492       if (atomictable.get(fn).intValue()!=0) {
 493         if ((fn.numPrev()>0)&&atomictable.get(fn.getPrev(0)).intValue()==0) {
 494           //Everything live is old
 495           Set<TempDescriptor> lives=livetemps.get(fn);
 496           oldtemps=new HashSet<TempDescriptor>();
 497
 498           for(Iterator<TempDescriptor> it=lives.iterator();it.hasNext();) {
 499             TempDescriptor tmp=it.next();
 500             if (tmp.getType().isPtr()) {
 501               oldtemps.add(tmp);
 502             }
 503           }
 504         } else {
 505           oldtemps=new HashSet<TempDescriptor>();
 506           //Compute union of old temporaries
 507           for(int i=0;i<fn.numPrev();i++) {
 508             Set<TempDescriptor> pset=fntooldtmp.get(fn.getPrev(i));
 509             if (pset!=null)
 510               oldtemps.addAll(pset);
 511           }
 512
 513           switch (fn.kind()) {
 514           case FKind.FlatNew:
 515             oldtemps.removeAll(Arrays.asList(fn.readsTemps()));
 516             break;
 517           case FKind.FlatOpNode: {
 518             FlatOpNode fon=(FlatOpNode)fn;
 519             if (fon.getOp().getOp()==Operation.ASSIGN&&fon.getDest().getType().isPtr()) {
 520               if (oldtemps.contains(fon.getLeft()))
 521                 oldtemps.add(fon.getDest());
 522               else
 523                 oldtemps.remove(fon.getDest());
 524               break;
 525             }
 526           }
 527           default: {
 528             TempDescriptor[] writes=fn.writesTemps();
 529             for(int i=0;i<writes.length;i++) {
 530               TempDescriptor wtemp=writes[i];
 531               if (wtemp.getType().isPtr())
 532                 oldtemps.add(wtemp);
 533             }
 534           }
 535           }
 536         }
 537       }
 538
 539       if (oldtemps!=null) {
 540         if (!fntooldtmp.containsKey(fn)||!fntooldtmp.get(fn).equals(oldtemps)) {
 541           fntooldtmp.put(fn, oldtemps);
 542           //propagate changes
 543           for(int i=0;i<fn.numNext();i++) {
 544             FlatNode fnext=fn.getNext(i);
 545             tovisit.add(fnext);
 546           }
 547         }
 548       }
 549     }
 550     return fntooldtmp;
 551   }
 552 }
 553
 554 class TempFlatPair {
 555     FlatNode f;
 556     TempDescriptor t;
 557     TempFlatPair(TempDescriptor t, FlatNode f) {
 558         this.t=t;
 559         this.f=f;
 560     }
 561
 562     public int hashCode() {
 563         return f.hashCode()^t.hashCode();
 564     }
 565     public boolean equals(Object o) {
 566         TempFlatPair tf=(TempFlatPair)o;
 567         return t.equals(tf.t)&&f.equals(tf.f);
 568     }
 569 }