AliasSetTracker.cpp revision 199989
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" 26using namespace llvm; 27 28/// mergeSetIn - Merge the specified alias set into this alias set. 29/// 30void 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 75void 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 83void AliasSet::removeFromTracker(AliasSetTracker &AST) { 84 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!"); 85 AST.removeAliasSet(this); 86} 87 88void 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 116void 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/// 136bool 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 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 157 if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size) 158 != AliasAnalysis::NoModRef) 159 return true; 160 } 161 162 return false; 163} 164 165bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const { 166 if (AA.doesNotAccessMemory(CS)) 167 return false; 168 169 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 170 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef || 171 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef) 172 return true; 173 174 for (iterator I = begin(), E = end(); I != E; ++I) 175 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) != 176 AliasAnalysis::NoModRef) 177 return true; 178 179 return false; 180} 181 182void AliasSetTracker::clear() { 183 // Delete all the PointerRec entries. 184 for (PointerMapType::iterator I = PointerMap.begin(), E = PointerMap.end(); 185 I != E; ++I) 186 I->second->eraseFromList(); 187 188 PointerMap.clear(); 189 190 // The alias sets should all be clear now. 191 AliasSets.clear(); 192} 193 194 195/// findAliasSetForPointer - Given a pointer, find the one alias set to put the 196/// instruction referring to the pointer into. If there are multiple alias sets 197/// that may alias the pointer, merge them together and return the unified set. 198/// 199AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr, 200 unsigned Size) { 201 AliasSet *FoundSet = 0; 202 for (iterator I = begin(), E = end(); I != E; ++I) 203 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) { 204 if (FoundSet == 0) { // If this is the first alias set ptr can go into. 205 FoundSet = I; // Remember it. 206 } else { // Otherwise, we must merge the sets. 207 FoundSet->mergeSetIn(*I, *this); // Merge in contents. 208 } 209 } 210 211 return FoundSet; 212} 213 214/// containsPointer - Return true if the specified location is represented by 215/// this alias set, false otherwise. This does not modify the AST object or 216/// alias sets. 217bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const { 218 for (const_iterator I = begin(), E = end(); I != E; ++I) 219 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) 220 return true; 221 return false; 222} 223 224 225 226AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) { 227 AliasSet *FoundSet = 0; 228 for (iterator I = begin(), E = end(); I != E; ++I) 229 if (!I->Forward && I->aliasesCallSite(CS, AA)) { 230 if (FoundSet == 0) { // If this is the first alias set ptr can go into. 231 FoundSet = I; // Remember it. 232 } else if (!I->Forward) { // Otherwise, we must merge the sets. 233 FoundSet->mergeSetIn(*I, *this); // Merge in contents. 234 } 235 } 236 237 return FoundSet; 238} 239 240 241 242 243/// getAliasSetForPointer - Return the alias set that the specified pointer 244/// lives in. 245AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size, 246 bool *New) { 247 AliasSet::PointerRec &Entry = getEntryFor(Pointer); 248 249 // Check to see if the pointer is already known... 250 if (Entry.hasAliasSet()) { 251 Entry.updateSize(Size); 252 // Return the set! 253 return *Entry.getAliasSet(*this)->getForwardedTarget(*this); 254 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) { 255 // Add it to the alias set it aliases... 256 AS->addPointer(*this, Entry, Size); 257 return *AS; 258 } else { 259 if (New) *New = true; 260 // Otherwise create a new alias set to hold the loaded pointer... 261 AliasSets.push_back(new AliasSet()); 262 AliasSets.back().addPointer(*this, Entry, Size); 263 return AliasSets.back(); 264 } 265} 266 267bool AliasSetTracker::add(Value *Ptr, unsigned Size) { 268 bool NewPtr; 269 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr); 270 return NewPtr; 271} 272 273 274bool AliasSetTracker::add(LoadInst *LI) { 275 bool NewPtr; 276 AliasSet &AS = addPointer(LI->getOperand(0), 277 AA.getTypeStoreSize(LI->getType()), 278 AliasSet::Refs, NewPtr); 279 if (LI->isVolatile()) AS.setVolatile(); 280 return NewPtr; 281} 282 283bool AliasSetTracker::add(StoreInst *SI) { 284 bool NewPtr; 285 Value *Val = SI->getOperand(0); 286 AliasSet &AS = addPointer(SI->getOperand(1), 287 AA.getTypeStoreSize(Val->getType()), 288 AliasSet::Mods, NewPtr); 289 if (SI->isVolatile()) AS.setVolatile(); 290 return NewPtr; 291} 292 293bool AliasSetTracker::add(VAArgInst *VAAI) { 294 bool NewPtr; 295 addPointer(VAAI->getOperand(0), ~0, AliasSet::ModRef, NewPtr); 296 return NewPtr; 297} 298 299 300bool AliasSetTracker::add(CallSite CS) { 301 if (isa<DbgInfoIntrinsic>(CS.getInstruction())) 302 return true; // Ignore DbgInfo Intrinsics. 303 if (AA.doesNotAccessMemory(CS)) 304 return true; // doesn't alias anything 305 306 AliasSet *AS = findAliasSetForCallSite(CS); 307 if (!AS) { 308 AliasSets.push_back(new AliasSet()); 309 AS = &AliasSets.back(); 310 AS->addCallSite(CS, AA); 311 return true; 312 } else { 313 AS->addCallSite(CS, AA); 314 return false; 315 } 316} 317 318bool AliasSetTracker::add(Instruction *I) { 319 // Dispatch to one of the other add methods... 320 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 321 return add(LI); 322 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 323 return add(SI); 324 else if (CallInst *CI = dyn_cast<CallInst>(I)) 325 return add(CI); 326 else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 327 return add(II); 328 else if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I)) 329 return add(VAAI); 330 return true; 331} 332 333void AliasSetTracker::add(BasicBlock &BB) { 334 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) 335 add(I); 336} 337 338void AliasSetTracker::add(const AliasSetTracker &AST) { 339 assert(&AA == &AST.AA && 340 "Merging AliasSetTracker objects with different Alias Analyses!"); 341 342 // Loop over all of the alias sets in AST, adding the pointers contained 343 // therein into the current alias sets. This can cause alias sets to be 344 // merged together in the current AST. 345 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) 346 if (!I->Forward) { // Ignore forwarding alias sets 347 AliasSet &AS = const_cast<AliasSet&>(*I); 348 349 // If there are any call sites in the alias set, add them to this AST. 350 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i) 351 add(AS.CallSites[i]); 352 353 // Loop over all of the pointers in this alias set... 354 AliasSet::iterator I = AS.begin(), E = AS.end(); 355 bool X; 356 for (; I != E; ++I) { 357 AliasSet &NewAS = addPointer(I.getPointer(), I.getSize(), 358 (AliasSet::AccessType)AS.AccessTy, X); 359 if (AS.isVolatile()) NewAS.setVolatile(); 360 } 361 } 362} 363 364/// remove - Remove the specified (potentially non-empty) alias set from the 365/// tracker. 366void AliasSetTracker::remove(AliasSet &AS) { 367 // Drop all call sites. 368 AS.CallSites.clear(); 369 370 // Clear the alias set. 371 unsigned NumRefs = 0; 372 while (!AS.empty()) { 373 AliasSet::PointerRec *P = AS.PtrList; 374 375 Value *ValToRemove = P->getValue(); 376 377 // Unlink and delete entry from the list of values. 378 P->eraseFromList(); 379 380 // Remember how many references need to be dropped. 381 ++NumRefs; 382 383 // Finally, remove the entry. 384 PointerMap.erase(ValToRemove); 385 } 386 387 // Stop using the alias set, removing it. 388 AS.RefCount -= NumRefs; 389 if (AS.RefCount == 0) 390 AS.removeFromTracker(*this); 391} 392 393bool AliasSetTracker::remove(Value *Ptr, unsigned Size) { 394 AliasSet *AS = findAliasSetForPointer(Ptr, Size); 395 if (!AS) return false; 396 remove(*AS); 397 return true; 398} 399 400bool AliasSetTracker::remove(LoadInst *LI) { 401 unsigned Size = AA.getTypeStoreSize(LI->getType()); 402 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size); 403 if (!AS) return false; 404 remove(*AS); 405 return true; 406} 407 408bool AliasSetTracker::remove(StoreInst *SI) { 409 unsigned Size = AA.getTypeStoreSize(SI->getOperand(0)->getType()); 410 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size); 411 if (!AS) return false; 412 remove(*AS); 413 return true; 414} 415 416bool AliasSetTracker::remove(VAArgInst *VAAI) { 417 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0), ~0); 418 if (!AS) return false; 419 remove(*AS); 420 return true; 421} 422 423bool AliasSetTracker::remove(CallSite CS) { 424 if (AA.doesNotAccessMemory(CS)) 425 return false; // doesn't alias anything 426 427 AliasSet *AS = findAliasSetForCallSite(CS); 428 if (!AS) return false; 429 remove(*AS); 430 return true; 431} 432 433bool AliasSetTracker::remove(Instruction *I) { 434 // Dispatch to one of the other remove methods... 435 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 436 return remove(LI); 437 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 438 return remove(SI); 439 else if (CallInst *CI = dyn_cast<CallInst>(I)) 440 return remove(CI); 441 else if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I)) 442 return remove(VAAI); 443 return true; 444} 445 446 447// deleteValue method - This method is used to remove a pointer value from the 448// AliasSetTracker entirely. It should be used when an instruction is deleted 449// from the program to update the AST. If you don't use this, you would have 450// dangling pointers to deleted instructions. 451// 452void AliasSetTracker::deleteValue(Value *PtrVal) { 453 // Notify the alias analysis implementation that this value is gone. 454 AA.deleteValue(PtrVal); 455 456 // If this is a call instruction, remove the callsite from the appropriate 457 // AliasSet. 458 CallSite CS = CallSite::get(PtrVal); 459 if (CS.getInstruction()) 460 if (!AA.doesNotAccessMemory(CS)) 461 if (AliasSet *AS = findAliasSetForCallSite(CS)) 462 AS->removeCallSite(CS); 463 464 // First, look up the PointerRec for this pointer. 465 PointerMapType::iterator I = PointerMap.find(PtrVal); 466 if (I == PointerMap.end()) return; // Noop 467 468 // If we found one, remove the pointer from the alias set it is in. 469 AliasSet::PointerRec *PtrValEnt = I->second; 470 AliasSet *AS = PtrValEnt->getAliasSet(*this); 471 472 // Unlink and delete from the list of values. 473 PtrValEnt->eraseFromList(); 474 475 // Stop using the alias set. 476 AS->dropRef(*this); 477 478 PointerMap.erase(I); 479} 480 481// copyValue - This method should be used whenever a preexisting value in the 482// program is copied or cloned, introducing a new value. Note that it is ok for 483// clients that use this method to introduce the same value multiple times: if 484// the tracker already knows about a value, it will ignore the request. 485// 486void AliasSetTracker::copyValue(Value *From, Value *To) { 487 // Notify the alias analysis implementation that this value is copied. 488 AA.copyValue(From, To); 489 490 // First, look up the PointerRec for this pointer. 491 PointerMapType::iterator I = PointerMap.find(From); 492 if (I == PointerMap.end()) 493 return; // Noop 494 assert(I->second->hasAliasSet() && "Dead entry?"); 495 496 AliasSet::PointerRec &Entry = getEntryFor(To); 497 if (Entry.hasAliasSet()) return; // Already in the tracker! 498 499 // Add it to the alias set it aliases... 500 I = PointerMap.find(From); 501 AliasSet *AS = I->second->getAliasSet(*this); 502 AS->addPointer(*this, Entry, I->second->getSize(), true); 503} 504 505 506 507//===----------------------------------------------------------------------===// 508// AliasSet/AliasSetTracker Printing Support 509//===----------------------------------------------------------------------===// 510 511void AliasSet::print(raw_ostream &OS) const { 512 OS << " AliasSet[" << format("0x%p", (void*)this) << "," << RefCount << "] "; 513 OS << (AliasTy == MustAlias ? "must" : "may") << " alias, "; 514 switch (AccessTy) { 515 case NoModRef: OS << "No access "; break; 516 case Refs : OS << "Ref "; break; 517 case Mods : OS << "Mod "; break; 518 case ModRef : OS << "Mod/Ref "; break; 519 default: llvm_unreachable("Bad value for AccessTy!"); 520 } 521 if (isVolatile()) OS << "[volatile] "; 522 if (Forward) 523 OS << " forwarding to " << (void*)Forward; 524 525 526 if (!empty()) { 527 OS << "Pointers: "; 528 for (iterator I = begin(), E = end(); I != E; ++I) { 529 if (I != begin()) OS << ", "; 530 WriteAsOperand(OS << "(", I.getPointer()); 531 OS << ", " << I.getSize() << ")"; 532 } 533 } 534 if (!CallSites.empty()) { 535 OS << "\n " << CallSites.size() << " Call Sites: "; 536 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) { 537 if (i) OS << ", "; 538 WriteAsOperand(OS, CallSites[i].getCalledValue()); 539 } 540 } 541 OS << "\n"; 542} 543 544void AliasSetTracker::print(raw_ostream &OS) const { 545 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for " 546 << PointerMap.size() << " pointer values.\n"; 547 for (const_iterator I = begin(), E = end(); I != E; ++I) 548 I->print(OS); 549 OS << "\n"; 550} 551 552void AliasSet::dump() const { print(errs()); } 553void AliasSetTracker::dump() const { print(errs()); } 554 555//===----------------------------------------------------------------------===// 556// ASTCallbackVH Class Implementation 557//===----------------------------------------------------------------------===// 558 559void AliasSetTracker::ASTCallbackVH::deleted() { 560 assert(AST && "ASTCallbackVH called with a null AliasSetTracker!"); 561 AST->deleteValue(getValPtr()); 562 // this now dangles! 563} 564 565AliasSetTracker::ASTCallbackVH::ASTCallbackVH(Value *V, AliasSetTracker *ast) 566 : CallbackVH(V), AST(ast) {} 567 568AliasSetTracker::ASTCallbackVH & 569AliasSetTracker::ASTCallbackVH::operator=(Value *V) { 570 return *this = ASTCallbackVH(V, AST); 571} 572 573//===----------------------------------------------------------------------===// 574// AliasSetPrinter Pass 575//===----------------------------------------------------------------------===// 576 577namespace { 578 class AliasSetPrinter : public FunctionPass { 579 AliasSetTracker *Tracker; 580 public: 581 static char ID; // Pass identification, replacement for typeid 582 AliasSetPrinter() : FunctionPass(&ID) {} 583 584 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 585 AU.setPreservesAll(); 586 AU.addRequired<AliasAnalysis>(); 587 } 588 589 virtual bool runOnFunction(Function &F) { 590 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>()); 591 592 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) 593 Tracker->add(&*I); 594 Tracker->print(errs()); 595 delete Tracker; 596 return false; 597 } 598 }; 599} 600 601char AliasSetPrinter::ID = 0; 602static RegisterPass<AliasSetPrinter> 603X("print-alias-sets", "Alias Set Printer", false, true); 604