AliasSetTracker.cpp revision cc8d524a2433eb393b449005c67868928a5af084
1//===- AliasSetTracker.cpp - Alias Sets Tracker implementation-------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source 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/Target/TargetData.h" 19#include "llvm/Assembly/Writer.h" 20#include "llvm/Support/InstIterator.h" 21#include <iostream> 22using namespace llvm; 23 24/// mergeSetIn - Merge the specified alias set into this alias set. 25/// 26void AliasSet::mergeSetIn(AliasSet &AS, AliasSetTracker &AST) { 27 assert(!AS.Forward && "Alias set is already forwarding!"); 28 assert(!Forward && "This set is a forwarding set!!"); 29 30 // Update the alias and access types of this set... 31 AccessTy |= AS.AccessTy; 32 AliasTy |= AS.AliasTy; 33 34 if (AliasTy == MustAlias) { 35 // Check that these two merged sets really are must aliases. Since both 36 // used to be must-alias sets, we can just check any pointer from each set 37 // for aliasing. 38 AliasAnalysis &AA = AST.getAliasAnalysis(); 39 HashNodePair *L = getSomePointer(); 40 HashNodePair *R = AS.getSomePointer(); 41 42 // If the pointers are not a must-alias pair, this set becomes a may alias. 43 if (AA.alias(L->first, L->second.getSize(), R->first, R->second.getSize()) 44 != AliasAnalysis::MustAlias) 45 AliasTy = MayAlias; 46 } 47 48 if (CallSites.empty()) { // Merge call sites... 49 if (!AS.CallSites.empty()) 50 std::swap(CallSites, AS.CallSites); 51 } else if (!AS.CallSites.empty()) { 52 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end()); 53 AS.CallSites.clear(); 54 } 55 56 AS.Forward = this; // Forward across AS now... 57 addRef(); // AS is now pointing to us... 58 59 // Merge the list of constituent pointers... 60 if (AS.PtrList) { 61 *PtrListEnd = AS.PtrList; 62 AS.PtrList->second.setPrevInList(PtrListEnd); 63 PtrListEnd = AS.PtrListEnd; 64 65 AS.PtrList = 0; 66 AS.PtrListEnd = &AS.PtrList; 67 assert(*AS.PtrListEnd == 0 && "End of list is not null?"); 68 } 69} 70 71void AliasSetTracker::removeAliasSet(AliasSet *AS) { 72 if (AliasSet *Fwd = AS->Forward) { 73 Fwd->dropRef(*this); 74 AS->Forward = 0; 75 } 76 AliasSets.erase(AS); 77} 78 79void AliasSet::removeFromTracker(AliasSetTracker &AST) { 80 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!"); 81 AST.removeAliasSet(this); 82} 83 84void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry, 85 unsigned Size, bool KnownMustAlias) { 86 assert(!Entry.second.hasAliasSet() && "Entry already in set!"); 87 88 // Check to see if we have to downgrade to _may_ alias. 89 if (isMustAlias() && !KnownMustAlias) 90 if (HashNodePair *P = getSomePointer()) { 91 AliasAnalysis &AA = AST.getAliasAnalysis(); 92 AliasAnalysis::AliasResult Result = 93 AA.alias(P->first, P->second.getSize(), Entry.first, Size); 94 if (Result == AliasAnalysis::MayAlias) 95 AliasTy = MayAlias; 96 else // First entry of must alias must have maximum size! 97 P->second.updateSize(Size); 98 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!"); 99 } 100 101 Entry.second.setAliasSet(this); 102 Entry.second.updateSize(Size); 103 104 // Add it to the end of the list... 105 assert(*PtrListEnd == 0 && "End of list is not null?"); 106 *PtrListEnd = &Entry; 107 PtrListEnd = Entry.second.setPrevInList(PtrListEnd); 108 assert(*PtrListEnd == 0 && "End of list is not null?"); 109 addRef(); // Entry points to alias set... 110} 111 112void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) { 113 CallSites.push_back(CS); 114 115 if (Function *F = CS.getCalledFunction()) { 116 if (AA.doesNotAccessMemory(F)) 117 return; 118 else if (AA.onlyReadsMemory(F)) { 119 AliasTy = MayAlias; 120 AccessTy |= Refs; 121 return; 122 } 123 } 124 125 // FIXME: This should use mod/ref information to make this not suck so bad 126 AliasTy = MayAlias; 127 AccessTy = ModRef; 128} 129 130/// aliasesPointer - Return true if the specified pointer "may" (or must) 131/// alias one of the members in the set. 132/// 133bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size, 134 AliasAnalysis &AA) const { 135 if (AliasTy == MustAlias) { 136 assert(CallSites.empty() && "Illegal must alias set!"); 137 138 // If this is a set of MustAliases, only check to see if the pointer aliases 139 // SOME value in the set... 140 HashNodePair *SomePtr = getSomePointer(); 141 assert(SomePtr && "Empty must-alias set??"); 142 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size); 143 } 144 145 // If this is a may-alias set, we have to check all of the pointers in the set 146 // to be sure it doesn't alias the set... 147 for (iterator I = begin(), E = end(); I != E; ++I) 148 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize())) 149 return true; 150 151 // Check the call sites list and invoke list... 152 if (!CallSites.empty()) { 153 if (AA.hasNoModRefInfoForCalls()) 154 return true; 155 156 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 (Function *F = CS.getCalledFunction()) 167 if (AA.doesNotAccessMemory(F)) 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().getTypeSize(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().getTypeSize(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 return NewPtr; 290} 291 292 293bool AliasSetTracker::add(CallSite CS) { 294 if (Function *F = CS.getCalledFunction()) 295 if (AA.doesNotAccessMemory(F)) 296 return true; // doesn't alias anything 297 298 AliasSet *AS = findAliasSetForCallSite(CS); 299 if (!AS) { 300 AliasSets.push_back(new AliasSet()); 301 AS = &AliasSets.back(); 302 AS->addCallSite(CS, AA); 303 return true; 304 } else { 305 AS->addCallSite(CS, AA); 306 return false; 307 } 308} 309 310bool AliasSetTracker::add(Instruction *I) { 311 // Dispatch to one of the other add methods... 312 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 313 return add(LI); 314 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 315 return add(SI); 316 else if (CallInst *CI = dyn_cast<CallInst>(I)) 317 return add(CI); 318 else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 319 return add(II); 320 else if (FreeInst *FI = dyn_cast<FreeInst>(I)) 321 return add(FI); 322 return true; 323} 324 325void AliasSetTracker::add(BasicBlock &BB) { 326 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) 327 add(I); 328} 329 330void AliasSetTracker::add(const AliasSetTracker &AST) { 331 assert(&AA == &AST.AA && 332 "Merging AliasSetTracker objects with different Alias Analyses!"); 333 334 // Loop over all of the alias sets in AST, adding the pointers contained 335 // therein into the current alias sets. This can cause alias sets to be 336 // merged together in the current AST. 337 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) 338 if (!I->Forward) { // Ignore forwarding alias sets 339 AliasSet &AS = const_cast<AliasSet&>(*I); 340 341 // If there are any call sites in the alias set, add them to this AST. 342 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i) 343 add(AS.CallSites[i]); 344 345 // Loop over all of the pointers in this alias set... 346 AliasSet::iterator I = AS.begin(), E = AS.end(); 347 bool X; 348 for (; I != E; ++I) 349 addPointer(I.getPointer(), I.getSize(), 350 (AliasSet::AccessType)AS.AccessTy, X); 351 } 352} 353 354/// remove - Remove the specified (potentially non-empty) alias set from the 355/// tracker. 356void AliasSetTracker::remove(AliasSet &AS) { 357 bool SetDead; 358 do { 359 AliasSet::iterator I = AS.begin(); 360 Value *Ptr = I.getPointer(); ++I; 361 362 // deleteValue will delete the set automatically when the last pointer 363 // reference is destroyed. "Predict" when this will happen. 364 SetDead = I == AS.end(); 365 deleteValue(Ptr); // Delete all of the pointers from the set 366 } while (!SetDead); 367} 368 369bool AliasSetTracker::remove(Value *Ptr, unsigned Size) { 370 AliasSet *AS = findAliasSetForPointer(Ptr, Size); 371 if (!AS) return false; 372 remove(*AS); 373 return true; 374} 375 376bool AliasSetTracker::remove(LoadInst *LI) { 377 unsigned Size = AA.getTargetData().getTypeSize(LI->getType()); 378 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size); 379 if (!AS) return false; 380 remove(*AS); 381 return true; 382} 383 384bool AliasSetTracker::remove(StoreInst *SI) { 385 unsigned Size = AA.getTargetData().getTypeSize(SI->getOperand(0)->getType()); 386 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size); 387 if (!AS) return false; 388 remove(*AS); 389 return true; 390} 391 392bool AliasSetTracker::remove(FreeInst *FI) { 393 AliasSet *AS = findAliasSetForPointer(FI->getOperand(0), ~0); 394 if (!AS) return false; 395 remove(*AS); 396 return true; 397} 398 399bool AliasSetTracker::remove(CallSite CS) { 400 if (Function *F = CS.getCalledFunction()) 401 if (AA.doesNotAccessMemory(F)) 402 return false; // doesn't alias anything 403 404 AliasSet *AS = findAliasSetForCallSite(CS); 405 if (!AS) return false; 406 remove(*AS); 407 return true; 408} 409 410bool AliasSetTracker::remove(Instruction *I) { 411 // Dispatch to one of the other remove methods... 412 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 413 return remove(LI); 414 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 415 return remove(SI); 416 else if (CallInst *CI = dyn_cast<CallInst>(I)) 417 return remove(CI); 418 else if (FreeInst *FI = dyn_cast<FreeInst>(I)) 419 return remove(FI); 420 return true; 421} 422 423 424// deleteValue method - This method is used to remove a pointer value from the 425// AliasSetTracker entirely. It should be used when an instruction is deleted 426// from the program to update the AST. If you don't use this, you would have 427// dangling pointers to deleted instructions. 428// 429void AliasSetTracker::deleteValue(Value *PtrVal) { 430 // Notify the alias analysis implementation that this value is gone. 431 AA.deleteValue(PtrVal); 432 433 // First, look up the PointerRec for this pointer. 434 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal); 435 if (I == PointerMap.end()) return; // Noop 436 437 // If we found one, remove the pointer from the alias set it is in. 438 AliasSet::HashNodePair &PtrValEnt = *I; 439 AliasSet *AS = PtrValEnt.second.getAliasSet(*this); 440 441 // Unlink from the list of values... 442 PtrValEnt.second.removeFromList(); 443 // Stop using the alias set 444 AS->dropRef(*this); 445 PointerMap.erase(I); 446} 447 448// copyValue - This method should be used whenever a preexisting value in the 449// program is copied or cloned, introducing a new value. Note that it is ok for 450// clients that use this method to introduce the same value multiple times: if 451// the tracker already knows about a value, it will ignore the request. 452// 453void AliasSetTracker::copyValue(Value *From, Value *To) { 454 // Notify the alias analysis implementation that this value is copied. 455 AA.copyValue(From, To); 456 457 // First, look up the PointerRec for this pointer. 458 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(From); 459 if (I == PointerMap.end() || !I->second.hasAliasSet()) 460 return; // Noop 461 462 AliasSet::HashNodePair &Entry = getEntryFor(To); 463 if (Entry.second.hasAliasSet()) return; // Already in the tracker! 464 465 // Add it to the alias set it aliases... 466 AliasSet *AS = I->second.getAliasSet(*this); 467 AS->addPointer(*this, Entry, I->second.getSize(), true); 468} 469 470 471 472//===----------------------------------------------------------------------===// 473// AliasSet/AliasSetTracker Printing Support 474//===----------------------------------------------------------------------===// 475 476void AliasSet::print(std::ostream &OS) const { 477 OS << " AliasSet[" << (void*)this << "," << RefCount << "] "; 478 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, "; 479 switch (AccessTy) { 480 case NoModRef: OS << "No access "; break; 481 case Refs : OS << "Ref "; break; 482 case Mods : OS << "Mod "; break; 483 case ModRef : OS << "Mod/Ref "; break; 484 default: assert(0 && "Bad value for AccessTy!"); 485 } 486 if (isVolatile()) OS << "[volatile] "; 487 if (Forward) 488 OS << " forwarding to " << (void*)Forward; 489 490 491 if (begin() != end()) { 492 OS << "Pointers: "; 493 for (iterator I = begin(), E = end(); I != E; ++I) { 494 if (I != begin()) OS << ", "; 495 WriteAsOperand(OS << "(", I.getPointer()); 496 OS << ", " << I.getSize() << ")"; 497 } 498 } 499 if (!CallSites.empty()) { 500 OS << "\n " << CallSites.size() << " Call Sites: "; 501 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) { 502 if (i) OS << ", "; 503 WriteAsOperand(OS, CallSites[i].getCalledValue()); 504 } 505 } 506 OS << "\n"; 507} 508 509void AliasSetTracker::print(std::ostream &OS) const { 510 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for " 511 << PointerMap.size() << " pointer values.\n"; 512 for (const_iterator I = begin(), E = end(); I != E; ++I) 513 I->print(OS); 514 OS << "\n"; 515} 516 517void AliasSet::dump() const { print (std::cerr); } 518void AliasSetTracker::dump() const { print(std::cerr); } 519 520//===----------------------------------------------------------------------===// 521// AliasSetPrinter Pass 522//===----------------------------------------------------------------------===// 523 524namespace { 525 class AliasSetPrinter : public FunctionPass { 526 AliasSetTracker *Tracker; 527 public: 528 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 529 AU.setPreservesAll(); 530 AU.addRequired<AliasAnalysis>(); 531 } 532 533 virtual bool runOnFunction(Function &F) { 534 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>()); 535 536 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) 537 Tracker->add(&*I); 538 return false; 539 } 540 541 /// print - Convert to human readable form 542 virtual void print(std::ostream &OS) const { 543 Tracker->print(OS); 544 } 545 546 virtual void releaseMemory() { 547 delete Tracker; 548 } 549 }; 550 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer", 551 PassInfo::Analysis | PassInfo::Optimization); 552} 553