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