AliasSetTracker.cpp revision 844731a7f1909f55935e3514c9e713a62d67662e
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/Pass.h" 18#include "llvm/Type.h" 19#include "llvm/Target/TargetData.h" 20#include "llvm/Assembly/Writer.h" 21#include "llvm/Support/Compiler.h" 22#include "llvm/Support/InstIterator.h" 23#include "llvm/Support/Streams.h" 24using namespace llvm; 25 26/// mergeSetIn - Merge the specified alias set into this alias set. 27/// 28void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) { 29 assert(!AS.Forward && "Alias set is already forwarding!"); 30 assert(!Forward && "This set is a forwarding set!!"); 31 32 // Update the alias and access types of this set... 33 AccessTy |= AS.AccessTy; 34 AliasTy |= AS.AliasTy; 35 36 if (AliasTy == MustAlias) { 37 // Check that these two merged sets really are must aliases. Since both 38 // used to be must-alias sets, we can just check any pointer from each set 39 // for aliasing. 40 AliasAnalysis &AA = AST.getAliasAnalysis(); 41 HashNodePair *L = getSomePointer(); 42 HashNodePair *R = AS.getSomePointer(); 43 44 // If the pointers are not a must-alias pair, this set becomes a may alias. 45 if (AA.alias(L->first, L->second.getSize(), R->first, R->second.getSize()) 46 != AliasAnalysis::MustAlias) 47 AliasTy = MayAlias; 48 } 49 50 if (CallSites.empty()) { // Merge call sites... 51 if (!AS.CallSites.empty()) 52 std::swap(CallSites, AS.CallSites); 53 } else if (!AS.CallSites.empty()) { 54 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end()); 55 AS.CallSites.clear(); 56 } 57 58 AS.Forward = this; // Forward across AS now... 59 addRef(); // AS is now pointing to us... 60 61 // Merge the list of constituent pointers... 62 if (AS.PtrList) { 63 *PtrListEnd = AS.PtrList; 64 AS.PtrList->second.setPrevInList(PtrListEnd); 65 PtrListEnd = AS.PtrListEnd; 66 67 AS.PtrList = 0; 68 AS.PtrListEnd = &AS.PtrList; 69 assert(*AS.PtrListEnd == 0 && "End of list is not null?"); 70 } 71} 72 73void AliasSetTracker::removeAliasSet(AliasSet *AS) { 74 if (AliasSet *Fwd = AS->Forward) { 75 Fwd->dropRef(*this); 76 AS->Forward = 0; 77 } 78 AliasSets.erase(AS); 79} 80 81void AliasSet::removeFromTracker(AliasSetTracker &AST) { 82 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!"); 83 AST.removeAliasSet(this); 84} 85 86void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry, 87 unsigned Size, bool KnownMustAlias) { 88 assert(!Entry.second.hasAliasSet() && "Entry already in set!"); 89 90 // Check to see if we have to downgrade to _may_ alias. 91 if (isMustAlias() && !KnownMustAlias) 92 if (HashNodePair *P = getSomePointer()) { 93 AliasAnalysis &AA = AST.getAliasAnalysis(); 94 AliasAnalysis::AliasResult Result = 95 AA.alias(P->first, P->second.getSize(), Entry.first, Size); 96 if (Result == AliasAnalysis::MayAlias) 97 AliasTy = MayAlias; 98 else // First entry of must alias must have maximum size! 99 P->second.updateSize(Size); 100 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!"); 101 } 102 103 Entry.second.setAliasSet(this); 104 Entry.second.updateSize(Size); 105 106 // Add it to the end of the list... 107 assert(*PtrListEnd == 0 && "End of list is not null?"); 108 *PtrListEnd = &Entry; 109 PtrListEnd = Entry.second.setPrevInList(PtrListEnd); 110 assert(*PtrListEnd == 0 && "End of list is not null?"); 111 addRef(); // Entry points to alias set... 112} 113 114void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) { 115 CallSites.push_back(CS); 116 117 AliasAnalysis::ModRefBehavior Behavior = AA.getModRefBehavior(CS); 118 if (Behavior == AliasAnalysis::DoesNotAccessMemory) 119 return; 120 else if (Behavior == AliasAnalysis::OnlyReadsMemory) { 121 AliasTy = MayAlias; 122 AccessTy |= Refs; 123 return; 124 } 125 126 // FIXME: This should use mod/ref information to make this not suck so bad 127 AliasTy = MayAlias; 128 AccessTy = ModRef; 129} 130 131/// aliasesPointer - Return true if the specified pointer "may" (or must) 132/// alias one of the members in the set. 133/// 134bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size, 135 AliasAnalysis &AA) const { 136 if (AliasTy == MustAlias) { 137 assert(CallSites.empty() && "Illegal must alias set!"); 138 139 // If this is a set of MustAliases, only check to see if the pointer aliases 140 // SOME value in the set... 141 HashNodePair *SomePtr = getSomePointer(); 142 assert(SomePtr && "Empty must-alias set??"); 143 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size); 144 } 145 146 // If this is a may-alias set, we have to check all of the pointers in the set 147 // to be sure it doesn't alias the set... 148 for (iterator I = begin(), E = end(); I != E; ++I) 149 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize())) 150 return true; 151 152 // Check the call sites list and invoke list... 153 if (!CallSites.empty()) { 154 if (AA.hasNoModRefInfoForCalls()) 155 return true; 156 157 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 if (AA.hasNoModRefInfoForCalls()) 171 return true; 172 173 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 174 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef || 175 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef) 176 return true; 177 178 for (iterator I = begin(), E = end(); I != E; ++I) 179 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) != 180 AliasAnalysis::NoModRef) 181 return true; 182 183 return false; 184} 185 186 187/// findAliasSetForPointer - Given a pointer, find the one alias set to put the 188/// instruction referring to the pointer into. If there are multiple alias sets 189/// that may alias the pointer, merge them together and return the unified set. 190/// 191AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr, 192 unsigned Size) { 193 AliasSet *FoundSet = 0; 194 for (iterator I = begin(), E = end(); I != E; ++I) 195 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) { 196 if (FoundSet == 0) { // If this is the first alias set ptr can go into. 197 FoundSet = I; // Remember it. 198 } else { // Otherwise, we must merge the sets. 199 FoundSet->mergeSetIn(*I, *this); // Merge in contents. 200 } 201 } 202 203 return FoundSet; 204} 205 206/// containsPointer - Return true if the specified location is represented by 207/// this alias set, false otherwise. This does not modify the AST object or 208/// alias sets. 209bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const { 210 for (const_iterator I = begin(), E = end(); I != E; ++I) 211 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) 212 return true; 213 return false; 214} 215 216 217 218AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) { 219 AliasSet *FoundSet = 0; 220 for (iterator I = begin(), E = end(); I != E; ++I) 221 if (!I->Forward && I->aliasesCallSite(CS, AA)) { 222 if (FoundSet == 0) { // If this is the first alias set ptr can go into. 223 FoundSet = I; // Remember it. 224 } else if (!I->Forward) { // Otherwise, we must merge the sets. 225 FoundSet->mergeSetIn(*I, *this); // Merge in contents. 226 } 227 } 228 229 return FoundSet; 230} 231 232 233 234 235/// getAliasSetForPointer - Return the alias set that the specified pointer 236/// lives in... 237AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size, 238 bool *New) { 239 AliasSet::HashNodePair &Entry = getEntryFor(Pointer); 240 241 // Check to see if the pointer is already known... 242 if (Entry.second.hasAliasSet()) { 243 Entry.second.updateSize(Size); 244 // Return the set! 245 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this); 246 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) { 247 // Add it to the alias set it aliases... 248 AS->addPointer(*this, Entry, Size); 249 return *AS; 250 } else { 251 if (New) *New = true; 252 // Otherwise create a new alias set to hold the loaded pointer... 253 AliasSets.push_back(new AliasSet()); 254 AliasSets.back().addPointer(*this, Entry, Size); 255 return AliasSets.back(); 256 } 257} 258 259bool AliasSetTracker::add(Value *Ptr, unsigned Size) { 260 bool NewPtr; 261 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr); 262 return NewPtr; 263} 264 265 266bool AliasSetTracker::add(LoadInst *LI) { 267 bool NewPtr; 268 AliasSet &AS = addPointer(LI->getOperand(0), 269 AA.getTargetData().getTypeStoreSize(LI->getType()), 270 AliasSet::Refs, NewPtr); 271 if (LI->isVolatile()) AS.setVolatile(); 272 return NewPtr; 273} 274 275bool AliasSetTracker::add(StoreInst *SI) { 276 bool NewPtr; 277 Value *Val = SI->getOperand(0); 278 AliasSet &AS = addPointer(SI->getOperand(1), 279 AA.getTargetData().getTypeStoreSize(Val->getType()), 280 AliasSet::Mods, NewPtr); 281 if (SI->isVolatile()) AS.setVolatile(); 282 return NewPtr; 283} 284 285bool AliasSetTracker::add(FreeInst *FI) { 286 bool NewPtr; 287 AliasSet &AS = addPointer(FI->getOperand(0), ~0, 288 AliasSet::Mods, NewPtr); 289 290 // Free operations are volatile ops (cannot be moved). 291 AS.setVolatile(); 292 return NewPtr; 293} 294 295bool AliasSetTracker::add(VAArgInst *VAAI) { 296 bool NewPtr; 297 addPointer(VAAI->getOperand(0), ~0, AliasSet::ModRef, NewPtr); 298 return NewPtr; 299} 300 301 302bool AliasSetTracker::add(CallSite CS) { 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 (FreeInst *FI = dyn_cast<FreeInst>(I)) 329 return add(FI); 330 else if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I)) 331 return add(VAAI); 332 return true; 333} 334 335void AliasSetTracker::add(BasicBlock &BB) { 336 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) 337 add(I); 338} 339 340void AliasSetTracker::add(const AliasSetTracker &AST) { 341 assert(&AA == &AST.AA && 342 "Merging AliasSetTracker objects with different Alias Analyses!"); 343 344 // Loop over all of the alias sets in AST, adding the pointers contained 345 // therein into the current alias sets. This can cause alias sets to be 346 // merged together in the current AST. 347 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) 348 if (!I->Forward) { // Ignore forwarding alias sets 349 AliasSet &AS = const_cast<AliasSet&>(*I); 350 351 // If there are any call sites in the alias set, add them to this AST. 352 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i) 353 add(AS.CallSites[i]); 354 355 // Loop over all of the pointers in this alias set... 356 AliasSet::iterator I = AS.begin(), E = AS.end(); 357 bool X; 358 for (; I != E; ++I) { 359 AliasSet &NewAS = addPointer(I.getPointer(), I.getSize(), 360 (AliasSet::AccessType)AS.AccessTy, X); 361 if (AS.isVolatile()) NewAS.setVolatile(); 362 } 363 } 364} 365 366/// remove - Remove the specified (potentially non-empty) alias set from the 367/// tracker. 368void AliasSetTracker::remove(AliasSet &AS) { 369 // Drop all call sites. 370 AS.CallSites.clear(); 371 372 // Clear the alias set. 373 unsigned NumRefs = 0; 374 while (!AS.empty()) { 375 AliasSet::HashNodePair *P = AS.PtrList; 376 377 // Unlink from the list of values. 378 P->second.removeFromList(); 379 380 // Remember how many references need to be dropped. 381 ++NumRefs; 382 383 // Finally, remove the entry. 384 Value *Remove = P->first; // Take a copy because it is invalid to pass 385 PointerMap.erase(Remove); // a reference to the data being erased. 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.getTargetData().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 = 411 AA.getTargetData().getTypeStoreSize(SI->getOperand(0)->getType()); 412 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size); 413 if (!AS) return false; 414 remove(*AS); 415 return true; 416} 417 418bool AliasSetTracker::remove(FreeInst *FI) { 419 AliasSet *AS = findAliasSetForPointer(FI->getOperand(0), ~0); 420 if (!AS) return false; 421 remove(*AS); 422 return true; 423} 424 425bool AliasSetTracker::remove(VAArgInst *VAAI) { 426 AliasSet *AS = findAliasSetForPointer(VAAI->getOperand(0), ~0); 427 if (!AS) return false; 428 remove(*AS); 429 return true; 430} 431 432bool AliasSetTracker::remove(CallSite CS) { 433 if (AA.doesNotAccessMemory(CS)) 434 return false; // doesn't alias anything 435 436 AliasSet *AS = findAliasSetForCallSite(CS); 437 if (!AS) return false; 438 remove(*AS); 439 return true; 440} 441 442bool AliasSetTracker::remove(Instruction *I) { 443 // Dispatch to one of the other remove methods... 444 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 445 return remove(LI); 446 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 447 return remove(SI); 448 else if (CallInst *CI = dyn_cast<CallInst>(I)) 449 return remove(CI); 450 else if (FreeInst *FI = dyn_cast<FreeInst>(I)) 451 return remove(FI); 452 else if (VAArgInst *VAAI = dyn_cast<VAArgInst>(I)) 453 return remove(VAAI); 454 return true; 455} 456 457 458// deleteValue method - This method is used to remove a pointer value from the 459// AliasSetTracker entirely. It should be used when an instruction is deleted 460// from the program to update the AST. If you don't use this, you would have 461// dangling pointers to deleted instructions. 462// 463void AliasSetTracker::deleteValue(Value *PtrVal) { 464 // Notify the alias analysis implementation that this value is gone. 465 AA.deleteValue(PtrVal); 466 467 // If this is a call instruction, remove the callsite from the appropriate 468 // AliasSet. 469 CallSite CS = CallSite::get(PtrVal); 470 if (CS.getInstruction()) 471 if (!AA.doesNotAccessMemory(CS)) 472 if (AliasSet *AS = findAliasSetForCallSite(CS)) 473 AS->removeCallSite(CS); 474 475 // First, look up the PointerRec for this pointer. 476 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal); 477 if (I == PointerMap.end()) return; // Noop 478 479 // If we found one, remove the pointer from the alias set it is in. 480 AliasSet::HashNodePair &PtrValEnt = *I; 481 AliasSet *AS = PtrValEnt.second.getAliasSet(*this); 482 483 // Unlink from the list of values... 484 PtrValEnt.second.removeFromList(); 485 // Stop using the alias set 486 AS->dropRef(*this); 487 PointerMap.erase(I); 488} 489 490// copyValue - This method should be used whenever a preexisting value in the 491// program is copied or cloned, introducing a new value. Note that it is ok for 492// clients that use this method to introduce the same value multiple times: if 493// the tracker already knows about a value, it will ignore the request. 494// 495void AliasSetTracker::copyValue(Value *From, Value *To) { 496 // Notify the alias analysis implementation that this value is copied. 497 AA.copyValue(From, To); 498 499 // First, look up the PointerRec for this pointer. 500 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(From); 501 if (I == PointerMap.end() || !I->second.hasAliasSet()) 502 return; // Noop 503 504 AliasSet::HashNodePair &Entry = getEntryFor(To); 505 if (Entry.second.hasAliasSet()) return; // Already in the tracker! 506 507 // Add it to the alias set it aliases... 508 AliasSet *AS = I->second.getAliasSet(*this); 509 AS->addPointer(*this, Entry, I->second.getSize(), true); 510} 511 512 513 514//===----------------------------------------------------------------------===// 515// AliasSet/AliasSetTracker Printing Support 516//===----------------------------------------------------------------------===// 517 518void AliasSet::print(std::ostream &OS) const { 519 OS << " AliasSet[" << (void*)this << "," << RefCount << "] "; 520 OS << (AliasTy == MustAlias ? "must" : "may") << " alias, "; 521 switch (AccessTy) { 522 case NoModRef: OS << "No access "; break; 523 case Refs : OS << "Ref "; break; 524 case Mods : OS << "Mod "; break; 525 case ModRef : OS << "Mod/Ref "; break; 526 default: assert(0 && "Bad value for AccessTy!"); 527 } 528 if (isVolatile()) OS << "[volatile] "; 529 if (Forward) 530 OS << " forwarding to " << (void*)Forward; 531 532 533 if (!empty()) { 534 OS << "Pointers: "; 535 for (iterator I = begin(), E = end(); I != E; ++I) { 536 if (I != begin()) OS << ", "; 537 WriteAsOperand(OS << "(", I.getPointer()); 538 OS << ", " << I.getSize() << ")"; 539 } 540 } 541 if (!CallSites.empty()) { 542 OS << "\n " << CallSites.size() << " Call Sites: "; 543 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) { 544 if (i) OS << ", "; 545 WriteAsOperand(OS, CallSites[i].getCalledValue()); 546 } 547 } 548 OS << "\n"; 549} 550 551void AliasSetTracker::print(std::ostream &OS) const { 552 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for " 553 << PointerMap.size() << " pointer values.\n"; 554 for (const_iterator I = begin(), E = end(); I != E; ++I) 555 I->print(OS); 556 OS << "\n"; 557} 558 559void AliasSet::dump() const { print (cerr); } 560void AliasSetTracker::dump() const { print(cerr); } 561 562//===----------------------------------------------------------------------===// 563// AliasSetPrinter Pass 564//===----------------------------------------------------------------------===// 565 566namespace { 567 class VISIBILITY_HIDDEN AliasSetPrinter : public FunctionPass { 568 AliasSetTracker *Tracker; 569 public: 570 static char ID; // Pass identification, replacement for typeid 571 AliasSetPrinter() : FunctionPass((intptr_t)&ID) {} 572 573 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 574 AU.setPreservesAll(); 575 AU.addRequired<AliasAnalysis>(); 576 } 577 578 virtual bool runOnFunction(Function &F) { 579 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>()); 580 581 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) 582 Tracker->add(&*I); 583 Tracker->print(cerr); 584 delete Tracker; 585 return false; 586 } 587 }; 588} 589 590char AliasSetPrinter::ID = 0; 591static RegisterPass<AliasSetPrinter> 592X("print-alias-sets", "Alias Set Printer", false, true); 593