AliasSetTracker.cpp revision d13db2c59cc94162d6cf0a04187d408bfef6d4a7
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/Debug.h" 23#include "llvm/Support/ErrorHandling.h" 24#include "llvm/Support/InstIterator.h" 25#include "llvm/Support/Format.h" 26#include "llvm/Support/raw_ostream.h" 27using namespace llvm; 28 29/// mergeSetIn - Merge the specified alias set into this alias set. 30/// 31void 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 39 if (AliasTy == MustAlias) { 40 // Check that these two merged sets really are must aliases. Since both 41 // used to be must-alias sets, we can just check any pointer from each set 42 // for aliasing. 43 AliasAnalysis &AA = AST.getAliasAnalysis(); 44 PointerRec *L = getSomePointer(); 45 PointerRec *R = AS.getSomePointer(); 46 47 // If the pointers are not a must-alias pair, this set becomes a may alias. 48 if (AA.alias(L->getValue(), L->getSize(), R->getValue(), R->getSize()) 49 != AliasAnalysis::MustAlias) 50 AliasTy = MayAlias; 51 } 52 53 if (CallSites.empty()) { // Merge call sites... 54 if (!AS.CallSites.empty()) 55 std::swap(CallSites, AS.CallSites); 56 } else if (!AS.CallSites.empty()) { 57 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end()); 58 AS.CallSites.clear(); 59 } 60 61 AS.Forward = this; // Forward across AS now... 62 addRef(); // AS is now pointing to us... 63 64 // Merge the list of constituent pointers... 65 if (AS.PtrList) { 66 *PtrListEnd = AS.PtrList; 67 AS.PtrList->setPrevInList(PtrListEnd); 68 PtrListEnd = AS.PtrListEnd; 69 70 AS.PtrList = 0; 71 AS.PtrListEnd = &AS.PtrList; 72 assert(*AS.PtrListEnd == 0 && "End of list is not null?"); 73 } 74} 75 76void AliasSetTracker::removeAliasSet(AliasSet *AS) { 77 if (AliasSet *Fwd = AS->Forward) { 78 Fwd->dropRef(*this); 79 AS->Forward = 0; 80 } 81 AliasSets.erase(AS); 82} 83 84void AliasSet::removeFromTracker(AliasSetTracker &AST) { 85 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!"); 86 AST.removeAliasSet(this); 87} 88 89void AliasSet::addPointer(AliasSetTracker &AST, PointerRec &Entry, 90 unsigned Size, bool KnownMustAlias) { 91 assert(!Entry.hasAliasSet() && "Entry already in set!"); 92 93 // Check to see if we have to downgrade to _may_ alias. 94 if (isMustAlias() && !KnownMustAlias) 95 if (PointerRec *P = getSomePointer()) { 96 AliasAnalysis &AA = AST.getAliasAnalysis(); 97 AliasAnalysis::AliasResult Result = 98 AA.alias(P->getValue(), P->getSize(), Entry.getValue(), Size); 99 if (Result == AliasAnalysis::MayAlias) 100 AliasTy = MayAlias; 101 else // First entry of must alias must have maximum size! 102 P->updateSize(Size); 103 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!"); 104 } 105 106 Entry.setAliasSet(this); 107 Entry.updateSize(Size); 108 109 // Add it to the end of the list... 110 assert(*PtrListEnd == 0 && "End of list is not null?"); 111 *PtrListEnd = &Entry; 112 PtrListEnd = Entry.setPrevInList(PtrListEnd); 113 assert(*PtrListEnd == 0 && "End of list is not null?"); 114 addRef(); // Entry points to alias set... 115} 116 117void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) { 118 CallSites.push_back(CS); 119 120 AliasAnalysis::ModRefBehavior Behavior = AA.getModRefBehavior(CS); 121 if (Behavior == AliasAnalysis::DoesNotAccessMemory) 122 return; 123 else if (Behavior == AliasAnalysis::OnlyReadsMemory) { 124 AliasTy = MayAlias; 125 AccessTy |= Refs; 126 return; 127 } 128 129 // FIXME: This should use mod/ref information to make this not suck so bad 130 AliasTy = MayAlias; 131 AccessTy = ModRef; 132} 133 134/// aliasesPointer - Return true if the specified pointer "may" (or must) 135/// alias one of the members in the set. 136/// 137bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size, 138 AliasAnalysis &AA) const { 139 if (AliasTy == MustAlias) { 140 assert(CallSites.empty() && "Illegal must alias set!"); 141 142 // If this is a set of MustAliases, only check to see if the pointer aliases 143 // SOME value in the set... 144 PointerRec *SomePtr = getSomePointer(); 145 assert(SomePtr && "Empty must-alias set??"); 146 return AA.alias(SomePtr->getValue(), SomePtr->getSize(), Ptr, Size); 147 } 148 149 // If this is a may-alias set, we have to check all of the pointers in the set 150 // to be sure it doesn't alias the set... 151 for (iterator I = begin(), E = end(); I != E; ++I) 152 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize())) 153 return true; 154 155 // Check the call sites list and invoke list... 156 if (!CallSites.empty()) { 157 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 158 if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size) 159 != AliasAnalysis::NoModRef) 160 return true; 161 } 162 163 return false; 164} 165 166bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const { 167 if (AA.doesNotAccessMemory(CS)) 168 return false; 169 170 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 171 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef || 172 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef) 173 return true; 174 175 for (iterator I = begin(), E = end(); I != E; ++I) 176 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) != 177 AliasAnalysis::NoModRef) 178 return true; 179 180 return false; 181} 182 183void AliasSetTracker::clear() { 184 // Delete all the PointerRec entries. 185 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end(); 186 I != E; ++I) 187 I->second->eraseFromList(); 188 189 PointerMap.clear(); 190 191 // The alias sets should all be clear now. 192 AliasSets.clear(); 193} 194 195 196/// findAliasSetForPointer - Given a pointer, find the one alias set to put the 197/// instruction referring to the pointer into. If there are multiple alias sets 198/// that may alias the pointer, merge them together and return the unified set. 199/// 200AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr, 201 unsigned Size) { 202 AliasSet *FoundSet = 0; 203 for (iterator I = begin(), E = end(); I != E; ++I) 204 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) { 205 if (FoundSet == 0) { // If this is the first alias set ptr can go into. 206 FoundSet = I; // Remember it. 207 } else { // Otherwise, we must merge the sets. 208 FoundSet->mergeSetIn(*I, *this); // Merge in contents. 209 } 210 } 211 212 return FoundSet; 213} 214 215/// containsPointer - Return true if the specified location is represented by 216/// this alias set, false otherwise. This does not modify the AST object or 217/// alias sets. 218bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const { 219 for (const_iterator I = begin(), E = end(); I != E; ++I) 220 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) 221 return true; 222 return false; 223} 224 225 226 227AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) { 228 AliasSet *FoundSet = 0; 229 for (iterator I = begin(), E = end(); I != E; ++I) 230 if (!I->Forward && I->aliasesCallSite(CS, AA)) { 231 if (FoundSet == 0) { // If this is the first alias set ptr can go into. 232 FoundSet = I; // Remember it. 233 } else if (!I->Forward) { // Otherwise, we must merge the sets. 234 FoundSet->mergeSetIn(*I, *this); // Merge in contents. 235 } 236 } 237 238 return FoundSet; 239} 240 241 242 243 244/// getAliasSetForPointer - Return the alias set that the specified pointer 245/// lives in. 246AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size, 247 bool *New) { 248 AliasSet::PointerRec &Entry = getEntryFor(Pointer); 249 250 // Check to see if the pointer is already known... 251 if (Entry.hasAliasSet()) { 252 Entry.updateSize(Size); 253 // Return the set! 254 return *Entry.getAliasSet(*this)->getForwardedTarget(*this); 255 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) { 256 // Add it to the alias set it aliases... 257 AS->addPointer(*this, Entry, Size); 258 return *AS; 259 } else { 260 if (New) *New = true; 261 // Otherwise create a new alias set to hold the loaded pointer... 262 AliasSets.push_back(new AliasSet()); 263 AliasSets.back().addPointer(*this, Entry, Size); 264 return AliasSets.back(); 265 } 266} 267 268bool AliasSetTracker::add(Value *Ptr, unsigned Size) { 269 bool NewPtr; 270 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr); 271 return NewPtr; 272} 273 274 275bool AliasSetTracker::add(LoadInst *LI) { 276 bool NewPtr; 277 AliasSet &AS = addPointer(LI->getOperand(0), 278 AA.getTypeStoreSize(LI->getType()), 279 AliasSet::Refs, NewPtr); 280 if (LI->isVolatile()) AS.setVolatile(); 281 return NewPtr; 282} 283 284bool AliasSetTracker::add(StoreInst *SI) { 285 bool NewPtr; 286 Value *Val = SI->getOperand(0); 287 AliasSet &AS = addPointer(SI->getOperand(1), 288 AA.getTypeStoreSize(Val->getType()), 289 AliasSet::Mods, NewPtr); 290 if (SI->isVolatile()) AS.setVolatile(); 291 return NewPtr; 292} 293 294bool AliasSetTracker::add(VAArgInst *VAAI) { 295 bool NewPtr; 296 addPointer(VAAI->getOperand(0), ~0, AliasSet::ModRef, NewPtr); 297 return NewPtr; 298} 299 300 301bool AliasSetTracker::add(CallSite CS) { 302 if (isa<DbgInfoIntrinsic>(CS.getInstruction())) 303 return true; // Ignore DbgInfo Intrinsics. 304 if (AA.doesNotAccessMemory(CS)) 305 return true; // doesn't alias anything 306 307 AliasSet *AS = findAliasSetForCallSite(CS); 308 if (!AS) { 309 AliasSets.push_back(new AliasSet()); 310 AS = &AliasSets.back(); 311 AS->addCallSite(CS, AA); 312 return true; 313 } else { 314 AS->addCallSite(CS, AA); 315 return false; 316 } 317} 318 319bool AliasSetTracker::add(Instruction *I) { 320 // Dispatch to one of the other add methods... 321 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 322 return add(LI); 323 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 324 return add(SI); 325 else if (CallInst *CI = dyn_cast<CallInst>(I)) 326 return add(CI); 327 else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 328 return add(II); 329 else if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I)) 330 return add(VAAI); 331 return true; 332} 333 334void AliasSetTracker::add(BasicBlock &BB) { 335 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) 336 add(I); 337} 338 339void AliasSetTracker::add(const AliasSetTracker &AST) { 340 assert(&AA == &AST.AA && 341 "Merging AliasSetTracker objects with different Alias Analyses!"); 342 343 // Loop over all of the alias sets in AST, adding the pointers contained 344 // therein into the current alias sets. This can cause alias sets to be 345 // merged together in the current AST. 346 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) 347 if (!I->Forward) { // Ignore forwarding alias sets 348 AliasSet &AS = const_cast<AliasSet&>(*I); 349 350 // If there are any call sites in the alias set, add them to this AST. 351 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i) 352 add(AS.CallSites[i]); 353 354 // Loop over all of the pointers in this alias set... 355 AliasSet::iterator I = AS.begin(), E = AS.end(); 356 bool X; 357 for (; I != E; ++I) { 358 AliasSet &NewAS = addPointer(I.getPointer(), I.getSize(), 359 (AliasSet::AccessType)AS.AccessTy, X); 360 if (AS.isVolatile()) NewAS.setVolatile(); 361 } 362 } 363} 364 365/// remove - Remove the specified (potentially non-empty) alias set from the 366/// tracker. 367void AliasSetTracker::remove(AliasSet &AS) { 368 // Drop all call sites. 369 AS.CallSites.clear(); 370 371 // Clear the alias set. 372 unsigned NumRefs = 0; 373 while (!AS.empty()) { 374 AliasSet::PointerRec *P = AS.PtrList; 375 376 Value *ValToRemove = P->getValue(); 377 378 // Unlink and delete entry from the list of values. 379 P->eraseFromList(); 380 381 // Remember how many references need to be dropped. 382 ++NumRefs; 383 384 // Finally, remove the entry. 385 PointerMap.erase(ValToRemove); 386 } 387 388 // Stop using the alias set, removing it. 389 AS.RefCount -= NumRefs; 390 if (AS.RefCount == 0) 391 AS.removeFromTracker(*this); 392} 393 394bool AliasSetTracker::remove(Value *Ptr, unsigned Size) { 395 AliasSet *AS = findAliasSetForPointer(Ptr, Size); 396 if (!AS) return false; 397 remove(*AS); 398 return true; 399} 400 401bool AliasSetTracker::remove(LoadInst *LI) { 402 unsigned Size = AA.getTypeStoreSize(LI->getType()); 403 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size); 404 if (!AS) return false; 405 remove(*AS); 406 return true; 407} 408 409bool AliasSetTracker::remove(StoreInst *SI) { 410 unsigned Size = AA.getTypeStoreSize(SI->getOperand(0)->getType()); 411 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size); 412 if (!AS) return false; 413 remove(*AS); 414 return true; 415} 416 417bool AliasSetTracker::remove(VAArgInst *VAAI) { 418 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0), ~0); 419 if (!AS) return false; 420 remove(*AS); 421 return true; 422} 423 424bool AliasSetTracker::remove(CallSite CS) { 425 if (AA.doesNotAccessMemory(CS)) 426 return false; // doesn't alias anything 427 428 AliasSet *AS = findAliasSetForCallSite(CS); 429 if (!AS) return false; 430 remove(*AS); 431 return true; 432} 433 434bool AliasSetTracker::remove(Instruction *I) { 435 // Dispatch to one of the other remove methods... 436 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 437 return remove(LI); 438 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 439 return remove(SI); 440 else if (CallInst *CI = dyn_cast<CallInst>(I)) 441 return remove(CI); 442 else if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I)) 443 return remove(VAAI); 444 return true; 445} 446 447 448// deleteValue method - This method is used to remove a pointer value from the 449// AliasSetTracker entirely. It should be used when an instruction is deleted 450// from the program to update the AST. If you don't use this, you would have 451// dangling pointers to deleted instructions. 452// 453void AliasSetTracker::deleteValue(Value *PtrVal) { 454 // Notify the alias analysis implementation that this value is gone. 455 AA.deleteValue(PtrVal); 456 457 // If this is a call instruction, remove the callsite from the appropriate 458 // AliasSet. 459 CallSite CS = CallSite::get(PtrVal); 460 if (CS.getInstruction()) 461 if (!AA.doesNotAccessMemory(CS)) 462 if (AliasSet *AS = findAliasSetForCallSite(CS)) 463 AS->removeCallSite(CS); 464 465 // First, look up the PointerRec for this pointer. 466 PointerMapType::iterator I = PointerMap.find(PtrVal); 467 if (I == PointerMap.end()) return; // Noop 468 469 // If we found one, remove the pointer from the alias set it is in. 470 AliasSet::PointerRec *PtrValEnt = I->second; 471 AliasSet *AS = PtrValEnt->getAliasSet(*this); 472 473 // Unlink and delete from the list of values. 474 PtrValEnt->eraseFromList(); 475 476 // Stop using the alias set. 477 AS->dropRef(*this); 478 479 PointerMap.erase(I); 480} 481 482// copyValue - This method should be used whenever a preexisting value in the 483// program is copied or cloned, introducing a new value. Note that it is ok for 484// clients that use this method to introduce the same value multiple times: if 485// the tracker already knows about a value, it will ignore the request. 486// 487void AliasSetTracker::copyValue(Value *From, Value *To) { 488 // Notify the alias analysis implementation that this value is copied. 489 AA.copyValue(From, To); 490 491 // First, look up the PointerRec for this pointer. 492 PointerMapType::iterator I = PointerMap.find(From); 493 if (I == PointerMap.end()) 494 return; // Noop 495 assert(I->second->hasAliasSet() && "Dead entry?"); 496 497 AliasSet::PointerRec &Entry = getEntryFor(To); 498 if (Entry.hasAliasSet()) return; // Already in the tracker! 499 500 // Add it to the alias set it aliases... 501 I = PointerMap.find(From); 502 AliasSet *AS = I->second->getAliasSet(*this); 503 AS->addPointer(*this, Entry, I->second->getSize(), true); 504} 505 506 507 508//===----------------------------------------------------------------------===// 509// AliasSet/AliasSetTracker Printing Support 510//===----------------------------------------------------------------------===// 511 512void AliasSet::print(raw_ostream &OS) const { 513 OS << " AliasSet[" << format("0x%p", (void*)this) << "," << RefCount << "] "; 514 OS << (AliasTy == MustAlias ? "must" : "may") << " alias, "; 515 switch (AccessTy) { 516 case NoModRef: OS << "No access "; break; 517 case Refs : OS << "Ref "; break; 518 case Mods : OS << "Mod "; break; 519 case ModRef : OS << "Mod/Ref "; break; 520 default: llvm_unreachable("Bad value for AccessTy!"); 521 } 522 if (isVolatile()) OS << "[volatile] "; 523 if (Forward) 524 OS << " forwarding to " << (void*)Forward; 525 526 527 if (!empty()) { 528 OS << "Pointers: "; 529 for (iterator I = begin(), E = end(); I != E; ++I) { 530 if (I != begin()) OS << ", "; 531 WriteAsOperand(OS << "(", I.getPointer()); 532 OS << ", " << I.getSize() << ")"; 533 } 534 } 535 if (!CallSites.empty()) { 536 OS << "\n " << CallSites.size() << " Call Sites: "; 537 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) { 538 if (i) OS << ", "; 539 WriteAsOperand(OS, CallSites[i].getCalledValue()); 540 } 541 } 542 OS << "\n"; 543} 544 545void AliasSetTracker::print(raw_ostream &OS) const { 546 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for " 547 << PointerMap.size() << " pointer values.\n"; 548 for (const_iterator I = begin(), E = end(); I != E; ++I) 549 I->print(OS); 550 OS << "\n"; 551} 552 553void AliasSet::dump() const { print(dbgs()); } 554void AliasSetTracker::dump() const { print(dbgs()); } 555 556//===----------------------------------------------------------------------===// 557// ASTCallbackVH Class Implementation 558//===----------------------------------------------------------------------===// 559 560void AliasSetTracker::ASTCallbackVH::deleted() { 561 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!"); 562 AST->deleteValue(getValPtr()); 563 // this now dangles! 564} 565 566AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast) 567 : CallbackVH(V), AST(ast) {} 568 569AliasSetTracker::ASTCallbackVH & 570AliasSetTracker::ASTCallbackVH::operator=(Value *V) { 571 return *this = ASTCallbackVH(V, AST); 572} 573 574//===----------------------------------------------------------------------===// 575// AliasSetPrinter Pass 576//===----------------------------------------------------------------------===// 577 578namespace { 579 class AliasSetPrinter : public FunctionPass { 580 AliasSetTracker *Tracker; 581 public: 582 static char ID; // Pass identification, replacement for typeid 583 AliasSetPrinter() : FunctionPass(&ID) {} 584 585 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 586 AU.setPreservesAll(); 587 AU.addRequired<AliasAnalysis>(); 588 } 589 590 virtual bool runOnFunction(Function &F) { 591 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>()); 592 593 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) 594 Tracker->add(&*I); 595 Tracker->print(errs()); 596 delete Tracker; 597 return false; 598 } 599 }; 600} 601 602char AliasSetPrinter::ID = 0; 603INITIALIZE_PASS(AliasSetPrinter, "print-alias-sets", 604 "Alias Set Printer", false, true); 605