lib/Analysis/AliasSetTracker.cpp

   1 //===- AliasSetTracker.cpp - Alias Sets Tracker implementation-------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the AliasSetTracker and AliasSet classes.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Analysis/AliasSetTracker.h"
  15 #include "llvm/Analysis/AliasAnalysis.h"
  16 #include "llvm/Instructions.h"
  17 #include "llvm/IntrinsicInst.h"
  18 #include "llvm/LLVMContext.h"
  19 #include "llvm/Pass.h"
  20 #include "llvm/Type.h"
  21 #include "llvm/Target/TargetData.h"
  22 #include "llvm/Assembly/Writer.h"
  23 #include "llvm/Support/Debug.h"
  24 #include "llvm/Support/ErrorHandling.h"
  25 #include "llvm/Support/InstIterator.h"
  26 #include "llvm/Support/raw_ostream.h"
  27 using namespace llvm;
  28
  29 /// mergeSetIn - Merge the specified alias set into this alias set.
  30 ///
  31 void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) {
  32   assert(!AS.Forward && "Alias set is already forwarding!");
  33   assert(!Forward && "This set is a forwarding set!!");
  34
  35   // Update the alias and access types of this set...
  36   AccessTy |= AS.AccessTy;
  37   AliasTy  |= AS.AliasTy;
  38   Volatile |= AS.Volatile;
  39
  40   if (AliasTy == MustAlias) {
  41     // Check that these two merged sets really are must aliases.  Since both
  42     // used to be must-alias sets, we can just check any pointer from each set
  43     // for aliasing.
  44     AliasAnalysis &AA = AST.getAliasAnalysis();
  45     PointerRec *L = getSomePointer();
  46     PointerRec *R = AS.getSomePointer();
  47
  48     // If the pointers are not a must-alias pair, this set becomes a may alias.
  49     if (AA.alias(AliasAnalysis::Location(L->getValue(),
  50                                          L->getSize(),
  51                                          L->getTBAAInfo()),
  52                  AliasAnalysis::Location(R->getValue(),
  53                                          R->getSize(),
  54                                          R->getTBAAInfo()))
  55         != AliasAnalysis::MustAlias)
  56       AliasTy = MayAlias;
  57   }
  58
  59   if (CallSites.empty()) {            // Merge call sites...
  60     if (!AS.CallSites.empty())
  61       std::swap(CallSites, AS.CallSites);
  62   } else if (!AS.CallSites.empty()) {
  63     CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end());
  64     AS.CallSites.clear();
  65   }
  66
  67   AS.Forward = this;  // Forward across AS now...
  68   addRef();           // AS is now pointing to us...
  69
  70   // Merge the list of constituent pointers...
  71   if (AS.PtrList) {
  72     *PtrListEnd = AS.PtrList;
  73     AS.PtrList->setPrevInList(PtrListEnd);
  74     PtrListEnd = AS.PtrListEnd;
  75
  76     AS.PtrList = 0;
  77     AS.PtrListEnd = &AS.PtrList;
  78     assert(*AS.PtrListEnd == 0 && "End of list is not null?");
  79   }
  80 }
  81
  82 void AliasSetTracker::removeAliasSet(AliasSet *AS) {
  83   if (AliasSet *Fwd = AS->Forward) {
  84     Fwd->dropRef(*this);
  85     AS->Forward = 0;
  86   }
  87   AliasSets.erase(AS);
  88 }
  89
  90 void AliasSet::removeFromTracker(AliasSetTracker &AST) {
  91   assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!");
  92   AST.removeAliasSet(this);
  93 }
  94
  95 void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry,
  96                           uint64_t Size, const MDNode *TBAAInfo,
  97                           bool KnownMustAlias) {
  98   assert(!Entry.hasAliasSet() && "Entry already in set!");
  99
 100   // Check to see if we have to downgrade to _may_ alias.
 101   if (isMustAlias() && !KnownMustAlias)
 102     if (PointerRec *P = getSomePointer()) {
 103       AliasAnalysis &AA = AST.getAliasAnalysis();
 104       AliasAnalysis::AliasResult Result =
 105         AA.alias(AliasAnalysis::Location(P->getValue(), P->getSize(),
 106                                          P->getTBAAInfo()),
 107                  AliasAnalysis::Location(Entry.getValue(), Size, TBAAInfo));
 108       if (Result != AliasAnalysis::MustAlias)
 109         AliasTy = MayAlias;
 110       else                  // First entry of must alias must have maximum size!
 111         P->updateSizeAndTBAAInfo(Size, TBAAInfo);
 112       assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!");
 113     }
 114
 115   Entry.setAliasSet(this);
 116   Entry.updateSizeAndTBAAInfo(Size, TBAAInfo);
 117
 118   // Add it to the end of the list...
 119   assert(*PtrListEnd == 0 && "End of list is not null?");
 120   *PtrListEnd = &Entry;
 121   PtrListEnd = Entry.setPrevInList(PtrListEnd);
 122   assert(*PtrListEnd == 0 && "End of list is not null?");
 123   addRef();               // Entry points to alias set.
 124 }
 125
 126 void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) {
 127   CallSites.push_back(CS.getInstruction());
 128
 129   AliasAnalysis::ModRefBehavior Behavior = AA.getModRefBehavior(CS);
 130   if (Behavior == AliasAnalysis::DoesNotAccessMemory)
 131     return;
 132   if (AliasAnalysis::onlyReadsMemory(Behavior)) {
 133     AliasTy = MayAlias;
 134     AccessTy |= Refs;
 135     return;
 136   }
 137
 138   // FIXME: This should use mod/ref information to make this not suck so bad
 139   AliasTy = MayAlias;
 140   AccessTy = ModRef;
 141 }
 142
 143 /// aliasesPointer - Return true if the specified pointer "may" (or must)
 144 /// alias one of the members in the set.
 145 ///
 146 bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
 147                               const MDNode *TBAAInfo,
 148                               AliasAnalysis &AA) const {
 149   if (AliasTy == MustAlias) {
 150     assert(CallSites.empty() && "Illegal must alias set!");
 151
 152     // If this is a set of MustAliases, only check to see if the pointer aliases
 153     // SOME value in the set.
 154     PointerRec *SomePtr = getSomePointer();
 155     assert(SomePtr && "Empty must-alias set??");
 156     return AA.alias(AliasAnalysis::Location(SomePtr->getValue(),
 157                                             SomePtr->getSize(),
 158                                             SomePtr->getTBAAInfo()),
 159                     AliasAnalysis::Location(Ptr, Size, TBAAInfo));
 160   }
 161
 162   // If this is a may-alias set, we have to check all of the pointers in the set
 163   // to be sure it doesn't alias the set...
 164   for (iterator I = begin(), E = end(); I != E; ++I)
 165     if (AA.alias(AliasAnalysis::Location(Ptr, Size, TBAAInfo),
 166                  AliasAnalysis::Location(I.getPointer(), I.getSize(),
 167                                          I.getTBAAInfo())))
 168       return true;
 169
 170   // Check the call sites list and invoke list...
 171   if (!CallSites.empty()) {
 172     for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
 173       if (AA.getModRefInfo(CallSites[i],
 174                            AliasAnalysis::Location(Ptr, Size, TBAAInfo)) !=
 175             AliasAnalysis::NoModRef)
 176         return true;
 177   }
 178
 179   return false;
 180 }
 181
 182 bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
 183   if (AA.doesNotAccessMemory(CS))
 184     return false;
 185
 186   for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
 187     if (AA.getModRefInfo(getCallSite(i), CS) != AliasAnalysis::NoModRef ||
 188         AA.getModRefInfo(CS, getCallSite(i)) != AliasAnalysis::NoModRef)
 189       return true;
 190   }
 191
 192   for (iterator I = begin(), E = end(); I != E; ++I)
 193     if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) !=
 194            AliasAnalysis::NoModRef)
 195       return true;
 196
 197   return false;
 198 }
 199
 200 void AliasSetTracker::clear() {
 201   // Delete all the PointerRec entries.
 202   for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end();
 203        I != E; ++I)
 204     I->second->eraseFromList();
 205
 206   PointerMap.clear();
 207
 208   // The alias sets should all be clear now.
 209   AliasSets.clear();
 210 }
 211
 212
 213 /// findAliasSetForPointer - Given a pointer, find the one alias set to put the
 214 /// instruction referring to the pointer into.  If there are multiple alias sets
 215 /// that may alias the pointer, merge them together and return the unified set.
 216 ///
 217 AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr,
 218                                                   uint64_t Size,
 219                                                   const MDNode *TBAAInfo) {
 220   AliasSet *FoundSet = 0;
 221   for (iterator I = begin(), E = end(); I != E; ++I) {
 222     if (I->Forward || !I->aliasesPointer(Ptr, Size, TBAAInfo, AA)) continue;
 223
 224     if (FoundSet == 0) {  // If this is the first alias set ptr can go into.
 225       FoundSet = I;       // Remember it.
 226     } else {              // Otherwise, we must merge the sets.
 227       FoundSet->mergeSetIn(*I, *this);     // Merge in contents.
 228     }
 229   }
 230
 231   return FoundSet;
 232 }
 233
 234 /// containsPointer - Return true if the specified location is represented by
 235 /// this alias set, false otherwise.  This does not modify the AST object or
 236 /// alias sets.
 237 bool AliasSetTracker::containsPointer(Value *Ptr, uint64_t Size,
 238                                       const MDNode *TBAAInfo) const {
 239   for (const_iterator I = begin(), E = end(); I != E; ++I)
 240     if (!I->Forward && I->aliasesPointer(Ptr, Size, TBAAInfo, AA))
 241       return true;
 242   return false;
 243 }
 244
 245
 246
 247 AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) {
 248   AliasSet *FoundSet = 0;
 249   for (iterator I = begin(), E = end(); I != E; ++I) {
 250     if (I->Forward || !I->aliasesCallSite(CS, AA))
 251       continue;
 252
 253     if (FoundSet == 0)        // If this is the first alias set ptr can go into.
 254       FoundSet = I;           // Remember it.
 255     else if (!I->Forward)     // Otherwise, we must merge the sets.
 256       FoundSet->mergeSetIn(*I, *this);     // Merge in contents.
 257   }
 258   return FoundSet;
 259 }
 260
 261
 262
 263
 264 /// getAliasSetForPointer - Return the alias set that the specified pointer
 265 /// lives in.
 266 AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, uint64_t Size,
 267                                                  const MDNode *TBAAInfo,
 268                                                  bool *New) {
 269   AliasSet::PointerRec &Entry = getEntryFor(Pointer);
 270
 271   // Check to see if the pointer is already known.
 272   if (Entry.hasAliasSet()) {
 273     Entry.updateSizeAndTBAAInfo(Size, TBAAInfo);
 274     // Return the set!
 275     return *Entry.getAliasSet(*this)->getForwardedTarget(*this);
 276   }
 277
 278   if (AliasSet *AS = findAliasSetForPointer(Pointer, Size, TBAAInfo)) {
 279     // Add it to the alias set it aliases.
 280     AS->addPointer(*this, Entry, Size, TBAAInfo);
 281     return *AS;
 282   }
 283
 284   if (New) *New = true;
 285   // Otherwise create a new alias set to hold the loaded pointer.
 286   AliasSets.push_back(new AliasSet());
 287   AliasSets.back().addPointer(*this, Entry, Size, TBAAInfo);
 288   return AliasSets.back();
 289 }
 290
 291 bool AliasSetTracker::add(Value *Ptr, uint64_t Size, const MDNode *TBAAInfo) {
 292   bool NewPtr;
 293   addPointer(Ptr, Size, TBAAInfo, AliasSet::NoModRef, NewPtr);
 294   return NewPtr;
 295 }
 296
 297
 298 bool AliasSetTracker::add(LoadInst *LI) {
 299   bool NewPtr;
 300   AliasSet &AS = addPointer(LI->getOperand(0),
 301                             AA.getTypeStoreSize(LI->getType()),
 302                             LI->getMetadata(LLVMContext::MD_tbaa),
 303                             AliasSet::Refs, NewPtr);
 304   if (LI->isVolatile()) AS.setVolatile();
 305   return NewPtr;
 306 }
 307
 308 bool AliasSetTracker::add(StoreInst *SI) {
 309   bool NewPtr;
 310   Value *Val = SI->getOperand(0);
 311   AliasSet &AS = addPointer(SI->getOperand(1),
 312                             AA.getTypeStoreSize(Val->getType()),
 313                             SI->getMetadata(LLVMContext::MD_tbaa),
 314                             AliasSet::Mods, NewPtr);
 315   if (SI->isVolatile()) AS.setVolatile();
 316   return NewPtr;
 317 }
 318
 319 bool AliasSetTracker::add(VAArgInst *VAAI) {
 320   bool NewPtr;
 321   addPointer(VAAI->getOperand(0), AliasAnalysis::UnknownSize,
 322              VAAI->getMetadata(LLVMContext::MD_tbaa),
 323              AliasSet::ModRef, NewPtr);
 324   return NewPtr;
 325 }
 326
 327
 328 bool AliasSetTracker::add(CallSite CS) {
 329   if (isa<DbgInfoIntrinsic>(CS.getInstruction()))
 330     return true; // Ignore DbgInfo Intrinsics.
 331   if (AA.doesNotAccessMemory(CS))
 332     return true; // doesn't alias anything
 333
 334   AliasSet *AS = findAliasSetForCallSite(CS);
 335   if (AS) {
 336     AS->addCallSite(CS, AA);
 337     return false;
 338   }
 339   AliasSets.push_back(new AliasSet());
 340   AS = &AliasSets.back();
 341   AS->addCallSite(CS, AA);
 342   return true;
 343 }
 344
 345 bool AliasSetTracker::add(Instruction *I) {
 346   // Dispatch to one of the other add methods.
 347   if (LoadInst *LI = dyn_cast<LoadInst>(I))
 348     return add(LI);
 349   if (StoreInst *SI = dyn_cast<StoreInst>(I))
 350     return add(SI);
 351   if (CallInst *CI = dyn_cast<CallInst>(I))
 352     return add(CI);
 353   if (InvokeInst *II = dyn_cast<InvokeInst>(I))
 354     return add(II);
 355   if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
 356     return add(VAAI);
 357   return true;
 358 }
 359
 360 void AliasSetTracker::add(BasicBlock &BB) {
 361   for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
 362     add(I);
 363 }
 364
 365 void AliasSetTracker::add(const AliasSetTracker &AST) {
 366   assert(&AA == &AST.AA &&
 367          "Merging AliasSetTracker objects with different Alias Analyses!");
 368
 369   // Loop over all of the alias sets in AST, adding the pointers contained
 370   // therein into the current alias sets.  This can cause alias sets to be
 371   // merged together in the current AST.
 372   for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) {
 373     if (I->Forward) continue;   // Ignore forwarding alias sets
 374
 375     AliasSet &AS = const_cast<AliasSet&>(*I);
 376
 377     // If there are any call sites in the alias set, add them to this AST.
 378     for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i)
 379       add(AS.CallSites[i]);
 380
 381     // Loop over all of the pointers in this alias set.
 382     bool X;
 383     for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
 384       AliasSet &NewAS = addPointer(ASI.getPointer(), ASI.getSize(),
 385                                    ASI.getTBAAInfo(),
 386                                    (AliasSet::AccessType)AS.AccessTy, X);
 387       if (AS.isVolatile()) NewAS.setVolatile();
 388     }
 389   }
 390 }
 391
 392 /// remove - Remove the specified (potentially non-empty) alias set from the
 393 /// tracker.
 394 void AliasSetTracker::remove(AliasSet &AS) {
 395   // Drop all call sites.
 396   AS.CallSites.clear();
 397
 398   // Clear the alias set.
 399   unsigned NumRefs = 0;
 400   while (!AS.empty()) {
 401     AliasSet::PointerRec *P = AS.PtrList;
 402
 403     Value *ValToRemove = P->getValue();
 404
 405     // Unlink and delete entry from the list of values.
 406     P->eraseFromList();
 407
 408     // Remember how many references need to be dropped.
 409     ++NumRefs;
 410
 411     // Finally, remove the entry.
 412     PointerMap.erase(ValToRemove);
 413   }
 414
 415   // Stop using the alias set, removing it.
 416   AS.RefCount -= NumRefs;
 417   if (AS.RefCount == 0)
 418     AS.removeFromTracker(*this);
 419 }
 420
 421 bool
 422 AliasSetTracker::remove(Value *Ptr, uint64_t Size, const MDNode *TBAAInfo) {
 423   AliasSet *AS = findAliasSetForPointer(Ptr, Size, TBAAInfo);
 424   if (!AS) return false;
 425   remove(*AS);
 426   return true;
 427 }
 428
 429 bool AliasSetTracker::remove(LoadInst *LI) {
 430   uint64_t Size = AA.getTypeStoreSize(LI->getType());
 431   const MDNode *TBAAInfo = LI->getMetadata(LLVMContext::MD_tbaa);
 432   AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size, TBAAInfo);
 433   if (!AS) return false;
 434   remove(*AS);
 435   return true;
 436 }
 437
 438 bool AliasSetTracker::remove(StoreInst *SI) {
 439   uint64_t Size = AA.getTypeStoreSize(SI->getOperand(0)->getType());
 440   const MDNode *TBAAInfo = SI->getMetadata(LLVMContext::MD_tbaa);
 441   AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size, TBAAInfo);
 442   if (!AS) return false;
 443   remove(*AS);
 444   return true;
 445 }
 446
 447 bool AliasSetTracker::remove(VAArgInst *VAAI) {
 448   AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0),
 449                                         AliasAnalysis::UnknownSize,
 450                                         VAAI->getMetadata(LLVMContext::MD_tbaa));
 451   if (!AS) return false;
 452   remove(*AS);
 453   return true;
 454 }
 455
 456 bool AliasSetTracker::remove(CallSite CS) {
 457   if (AA.doesNotAccessMemory(CS))
 458     return false; // doesn't alias anything
 459
 460   AliasSet *AS = findAliasSetForCallSite(CS);
 461   if (!AS) return false;
 462   remove(*AS);
 463   return true;
 464 }
 465
 466 bool AliasSetTracker::remove(Instruction *I) {
 467   // Dispatch to one of the other remove methods...
 468   if (LoadInst *LI = dyn_cast<LoadInst>(I))
 469     return remove(LI);
 470   if (StoreInst *SI = dyn_cast<StoreInst>(I))
 471     return remove(SI);
 472   if (CallInst *CI = dyn_cast<CallInst>(I))
 473     return remove(CI);
 474   if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I))
 475     return remove(VAAI);
 476   return true;
 477 }
 478
 479
 480 // deleteValue method - This method is used to remove a pointer value from the
 481 // AliasSetTracker entirely.  It should be used when an instruction is deleted
 482 // from the program to update the AST.  If you don't use this, you would have
 483 // dangling pointers to deleted instructions.
 484 //
 485 void AliasSetTracker::deleteValue(Value *PtrVal) {
 486   // Notify the alias analysis implementation that this value is gone.
 487   AA.deleteValue(PtrVal);
 488
 489   // If this is a call instruction, remove the callsite from the appropriate
 490   // AliasSet (if present).
 491   if (CallSite CS = PtrVal) {
 492     if (!AA.doesNotAccessMemory(CS)) {
 493       // Scan all the alias sets to see if this call site is contained.
 494       for (iterator I = begin(), E = end(); I != E; ++I) {
 495         if (I->Forward) continue;
 496
 497         I->removeCallSite(CS);
 498       }
 499     }
 500   }
 501
 502   // First, look up the PointerRec for this pointer.
 503   PointerMapType::iterator I = PointerMap.find(PtrVal);
 504   if (I == PointerMap.end()) return;  // Noop
 505
 506   // If we found one, remove the pointer from the alias set it is in.
 507   AliasSet::PointerRec *PtrValEnt = I->second;
 508   AliasSet *AS = PtrValEnt->getAliasSet(*this);
 509
 510   // Unlink and delete from the list of values.
 511   PtrValEnt->eraseFromList();
 512
 513   // Stop using the alias set.
 514   AS->dropRef(*this);
 515
 516   PointerMap.erase(I);
 517 }
 518
 519 // copyValue - This method should be used whenever a preexisting value in the
 520 // program is copied or cloned, introducing a new value.  Note that it is ok for
 521 // clients that use this method to introduce the same value multiple times: if
 522 // the tracker already knows about a value, it will ignore the request.
 523 //
 524 void AliasSetTracker::copyValue(Value *From, Value *To) {
 525   // Notify the alias analysis implementation that this value is copied.
 526   AA.copyValue(From, To);
 527
 528   // First, look up the PointerRec for this pointer.
 529   PointerMapType::iterator I = PointerMap.find(From);
 530   if (I == PointerMap.end())
 531     return;  // Noop
 532   assert(I->second->hasAliasSet() && "Dead entry?");
 533
 534   AliasSet::PointerRec &Entry = getEntryFor(To);
 535   if (Entry.hasAliasSet()) return;    // Already in the tracker!
 536
 537   // Add it to the alias set it aliases...
 538   I = PointerMap.find(From);
 539   AliasSet *AS = I->second->getAliasSet(*this);
 540   AS->addPointer(*this, Entry, I->second->getSize(),
 541                  I->second->getTBAAInfo(),
 542                  true);
 543 }
 544
 545
 546
 547 //===----------------------------------------------------------------------===//
 548 //               AliasSet/AliasSetTracker Printing Support
 549 //===----------------------------------------------------------------------===//
 550
 551 void AliasSet::print(raw_ostream &OS) const {
 552   OS << "  AliasSet[" << (void*)this << ", " << RefCount << "] ";
 553   OS << (AliasTy == MustAlias ? "must" : "may") << " alias, ";
 554   switch (AccessTy) {
 555   case NoModRef: OS << "No access "; break;
 556   case Refs    : OS << "Ref       "; break;
 557   case Mods    : OS << "Mod       "; break;
 558   case ModRef  : OS << "Mod/Ref   "; break;
 559   default: llvm_unreachable("Bad value for AccessTy!");
 560   }
 561   if (isVolatile()) OS << "[volatile] ";
 562   if (Forward)
 563     OS << " forwarding to " << (void*)Forward;
 564
 565
 566   if (!empty()) {
 567     OS << "Pointers: ";
 568     for (iterator I = begin(), E = end(); I != E; ++I) {
 569       if (I != begin()) OS << ", ";
 570       WriteAsOperand(OS << "(", I.getPointer());
 571       OS << ", " << I.getSize() << ")";
 572     }
 573   }
 574   if (!CallSites.empty()) {
 575     OS << "\n    " << CallSites.size() << " Call Sites: ";
 576     for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
 577       if (i) OS << ", ";
 578       WriteAsOperand(OS, CallSites[i]);
 579     }
 580   }
 581   OS << "\n";
 582 }
 583
 584 void AliasSetTracker::print(raw_ostream &OS) const {
 585   OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for "
 586      << PointerMap.size() << " pointer values.\n";
 587   for (const_iterator I = begin(), E = end(); I != E; ++I)
 588     I->print(OS);
 589   OS << "\n";
 590 }
 591
 592 void AliasSet::dump() const { print(dbgs()); }
 593 void AliasSetTracker::dump() const { print(dbgs()); }
 594
 595 //===----------------------------------------------------------------------===//
 596 //                     ASTCallbackVH Class Implementation
 597 //===----------------------------------------------------------------------===//
 598
 599 void AliasSetTracker::ASTCallbackVH::deleted() {
 600   assert(AST && "ASTCallbackVH called with a null AliasSetTracker!");
 601   AST->deleteValue(getValPtr());
 602   // this now dangles!
 603 }
 604
 605 void AliasSetTracker::ASTCallbackVH::allUsesReplacedWith(Value *V) {
 606   AST->copyValue(getValPtr(), V);
 607 }
 608
 609 AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast)
 610   : CallbackVH(V), AST(ast) {}
 611
 612 AliasSetTracker::ASTCallbackVH &
 613 AliasSetTracker::ASTCallbackVH::operator=(Value *V) {
 614   return *this = ASTCallbackVH(V, AST);
 615 }
 616
 617 //===----------------------------------------------------------------------===//
 618 //                            AliasSetPrinter Pass
 619 //===----------------------------------------------------------------------===//
 620
 621 namespace {
 622   class AliasSetPrinter : public FunctionPass {
 623     AliasSetTracker *Tracker;
 624   public:
 625     static char ID; // Pass identification, replacement for typeid
 626     AliasSetPrinter() : FunctionPass(ID) {
 627       initializeAliasSetPrinterPass(*PassRegistry::getPassRegistry());
 628     }
 629
 630     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
 631       AU.setPreservesAll();
 632       AU.addRequired<AliasAnalysis>();
 633     }
 634
 635     virtual bool runOnFunction(Function &F) {
 636       Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>());
 637
 638       for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
 639         Tracker->add(&*I);
 640       Tracker->print(errs());
 641       delete Tracker;
 642       return false;
 643     }
 644   };
 645 }
 646
 647 char AliasSetPrinter::ID = 0;
 648 INITIALIZE_PASS_BEGIN(AliasSetPrinter, "print-alias-sets",
 649                 "Alias Set Printer", false, true)
 650 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
 651 INITIALIZE_PASS_END(AliasSetPrinter, "print-alias-sets",
 652                 "Alias Set Printer", false, true)