AliasSetTracker.cpp revision 07bfa52405feb99155304c1a28b71e69d046589c
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) { 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 (CallSites.empty()) { // Merge call sites... 35 if (!AS.CallSites.empty()) 36 std::swap(CallSites, AS.CallSites); 37 } else if (!AS.CallSites.empty()) { 38 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end()); 39 AS.CallSites.clear(); 40 } 41 42 AS.Forward = this; // Forward across AS now... 43 addRef(); // AS is now pointing to us... 44 45 // Merge the list of constituent pointers... 46 if (AS.PtrList) { 47 *PtrListEnd = AS.PtrList; 48 AS.PtrList->second.setPrevInList(PtrListEnd); 49 PtrListEnd = AS.PtrListEnd; 50 51 AS.PtrList = 0; 52 AS.PtrListEnd = &AS.PtrList; 53 assert(*AS.PtrListEnd == 0 && "End of list is not null?"); 54 } 55} 56 57void AliasSetTracker::removeAliasSet(AliasSet *AS) { 58 if (AliasSet *Fwd = AS->Forward) { 59 Fwd->dropRef(*this); 60 AS->Forward = 0; 61 } 62 AliasSets.erase(AS); 63} 64 65void AliasSet::removeFromTracker(AliasSetTracker &AST) { 66 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!"); 67 AST.removeAliasSet(this); 68} 69 70void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry, 71 unsigned Size, bool KnownMustAlias) { 72 assert(!Entry.second.hasAliasSet() && "Entry already in set!"); 73 74 // Check to see if we have to downgrade to _may_ alias. 75 if (isMustAlias() && !KnownMustAlias) 76 if (HashNodePair *P = getSomePointer()) { 77 AliasAnalysis &AA = AST.getAliasAnalysis(); 78 AliasAnalysis::AliasResult Result = 79 AA.alias(P->first, P->second.getSize(), Entry.first, Size); 80 if (Result == AliasAnalysis::MayAlias) 81 AliasTy = MayAlias; 82 else // First entry of must alias must have maximum size! 83 P->second.updateSize(Size); 84 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!"); 85 } 86 87 Entry.second.setAliasSet(this); 88 Entry.second.updateSize(Size); 89 90 // Add it to the end of the list... 91 assert(*PtrListEnd == 0 && "End of list is not null?"); 92 *PtrListEnd = &Entry; 93 PtrListEnd = Entry.second.setPrevInList(PtrListEnd); 94 assert(*PtrListEnd == 0 && "End of list is not null?"); 95 addRef(); // Entry points to alias set... 96} 97 98void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) { 99 CallSites.push_back(CS); 100 101 if (Function *F = CS.getCalledFunction()) { 102 if (AA.doesNotAccessMemory(F)) 103 return; 104 else if (AA.onlyReadsMemory(F)) { 105 AliasTy = MayAlias; 106 AccessTy |= Refs; 107 return; 108 } 109 } 110 111 // FIXME: This should use mod/ref information to make this not suck so bad 112 AliasTy = MayAlias; 113 AccessTy = ModRef; 114} 115 116/// aliasesPointer - Return true if the specified pointer "may" (or must) 117/// alias one of the members in the set. 118/// 119bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size, 120 AliasAnalysis &AA) const { 121 if (AliasTy == MustAlias) { 122 assert(CallSites.empty() && "Illegal must alias set!"); 123 124 // If this is a set of MustAliases, only check to see if the pointer aliases 125 // SOME value in the set... 126 HashNodePair *SomePtr = getSomePointer(); 127 assert(SomePtr && "Empty must-alias set??"); 128 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size); 129 } 130 131 // If this is a may-alias set, we have to check all of the pointers in the set 132 // to be sure it doesn't alias the set... 133 for (iterator I = begin(), E = end(); I != E; ++I) 134 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize())) 135 return true; 136 137 // Check the call sites list and invoke list... 138 if (!CallSites.empty()) { 139 if (AA.hasNoModRefInfoForCalls()) 140 return true; 141 142 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 143 if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size) 144 != AliasAnalysis::NoModRef) 145 return true; 146 } 147 148 return false; 149} 150 151bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const { 152 if (Function *F = CS.getCalledFunction()) 153 if (AA.doesNotAccessMemory(F)) 154 return false; 155 156 if (AA.hasNoModRefInfoForCalls()) 157 return true; 158 159 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 160 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef || 161 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef) 162 return true; 163 164 for (iterator I = begin(), E = end(); I != E; ++I) 165 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) != 166 AliasAnalysis::NoModRef) 167 return true; 168 169 return false; 170} 171 172 173/// findAliasSetForPointer - Given a pointer, find the one alias set to put the 174/// instruction referring to the pointer into. If there are multiple alias sets 175/// that may alias the pointer, merge them together and return the unified set. 176/// 177AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr, 178 unsigned Size) { 179 AliasSet *FoundSet = 0; 180 for (iterator I = begin(), E = end(); I != E; ++I) 181 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) { 182 if (FoundSet == 0) { // If this is the first alias set ptr can go into... 183 FoundSet = I; // Remember it. 184 } else { // Otherwise, we must merge the sets... 185 FoundSet->mergeSetIn(*I); // Merge in contents... 186 } 187 } 188 189 return FoundSet; 190} 191 192/// containsPointer - Return true if the specified location is represented by 193/// this alias set, false otherwise. This does not modify the AST object or 194/// alias sets. 195bool AliasSetTracker::containsPointer(Value *Ptr, unsigned Size) const { 196 for (const_iterator I = begin(), E = end(); I != E; ++I) 197 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) 198 return true; 199 return false; 200} 201 202 203 204AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) { 205 AliasSet *FoundSet = 0; 206 for (iterator I = begin(), E = end(); I != E; ++I) 207 if (!I->Forward && I->aliasesCallSite(CS, AA)) { 208 if (FoundSet == 0) { // If this is the first alias set ptr can go into... 209 FoundSet = I; // Remember it. 210 } else if (!I->Forward) { // Otherwise, we must merge the sets... 211 FoundSet->mergeSetIn(*I); // Merge in contents... 212 } 213 } 214 215 return FoundSet; 216} 217 218 219 220 221/// getAliasSetForPointer - Return the alias set that the specified pointer 222/// lives in... 223AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size, 224 bool *New) { 225 AliasSet::HashNodePair &Entry = getEntryFor(Pointer); 226 227 // Check to see if the pointer is already known... 228 if (Entry.second.hasAliasSet()) { 229 Entry.second.updateSize(Size); 230 // Return the set! 231 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this); 232 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) { 233 // Add it to the alias set it aliases... 234 AS->addPointer(*this, Entry, Size); 235 return *AS; 236 } else { 237 if (New) *New = true; 238 // Otherwise create a new alias set to hold the loaded pointer... 239 AliasSets.push_back(new AliasSet()); 240 AliasSets.back().addPointer(*this, Entry, Size); 241 return AliasSets.back(); 242 } 243} 244 245bool AliasSetTracker::add(Value *Ptr, unsigned Size) { 246 bool NewPtr; 247 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr); 248 return NewPtr; 249} 250 251 252bool AliasSetTracker::add(LoadInst *LI) { 253 bool NewPtr; 254 AliasSet &AS = addPointer(LI->getOperand(0), 255 AA.getTargetData().getTypeSize(LI->getType()), 256 AliasSet::Refs, NewPtr); 257 if (LI->isVolatile()) AS.setVolatile(); 258 return NewPtr; 259} 260 261bool AliasSetTracker::add(StoreInst *SI) { 262 bool NewPtr; 263 Value *Val = SI->getOperand(0); 264 AliasSet &AS = addPointer(SI->getOperand(1), 265 AA.getTargetData().getTypeSize(Val->getType()), 266 AliasSet::Mods, NewPtr); 267 if (SI->isVolatile()) AS.setVolatile(); 268 return NewPtr; 269} 270 271bool AliasSetTracker::add(FreeInst *FI) { 272 bool NewPtr; 273 AliasSet &AS = addPointer(FI->getOperand(0), ~0, 274 AliasSet::Mods, NewPtr); 275 return NewPtr; 276} 277 278 279bool AliasSetTracker::add(CallSite CS) { 280 if (Function *F = CS.getCalledFunction()) 281 if (AA.doesNotAccessMemory(F)) 282 return true; // doesn't alias anything 283 284 AliasSet *AS = findAliasSetForCallSite(CS); 285 if (!AS) { 286 AliasSets.push_back(new AliasSet()); 287 AS = &AliasSets.back(); 288 AS->addCallSite(CS, AA); 289 return true; 290 } else { 291 AS->addCallSite(CS, AA); 292 return false; 293 } 294} 295 296bool AliasSetTracker::add(Instruction *I) { 297 // Dispatch to one of the other add methods... 298 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 299 return add(LI); 300 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 301 return add(SI); 302 else if (CallInst *CI = dyn_cast<CallInst>(I)) 303 return add(CI); 304 else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 305 return add(II); 306 else if (FreeInst *FI = dyn_cast<FreeInst>(I)) 307 return add(FI); 308 return true; 309} 310 311void AliasSetTracker::add(BasicBlock &BB) { 312 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) 313 add(I); 314} 315 316void AliasSetTracker::add(const AliasSetTracker &AST) { 317 assert(&AA == &AST.AA && 318 "Merging AliasSetTracker objects with different Alias Analyses!"); 319 320 // Loop over all of the alias sets in AST, adding the pointers contained 321 // therein into the current alias sets. This can cause alias sets to be 322 // merged together in the current AST. 323 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) 324 if (!I->Forward) { // Ignore forwarding alias sets 325 AliasSet &AS = const_cast<AliasSet&>(*I); 326 327 // If there are any call sites in the alias set, add them to this AST. 328 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i) 329 add(AS.CallSites[i]); 330 331 // Loop over all of the pointers in this alias set... 332 AliasSet::iterator I = AS.begin(), E = AS.end(); 333 bool X; 334 for (; I != E; ++I) 335 addPointer(I.getPointer(), I.getSize(), 336 (AliasSet::AccessType)AS.AccessTy, X); 337 } 338} 339 340/// remove - Remove the specified (potentially non-empty) alias set from the 341/// tracker. 342void AliasSetTracker::remove(AliasSet &AS) { 343 bool SetDead; 344 do { 345 AliasSet::iterator I = AS.begin(); 346 Value *Ptr = I.getPointer(); ++I; 347 348 // deleteValue will delete the set automatically when the last pointer 349 // reference is destroyed. "Predict" when this will happen. 350 SetDead = I == AS.end(); 351 deleteValue(Ptr); // Delete all of the pointers from the set 352 } while (!SetDead); 353} 354 355bool AliasSetTracker::remove(Value *Ptr, unsigned Size) { 356 AliasSet *AS = findAliasSetForPointer(Ptr, Size); 357 if (!AS) return false; 358 remove(*AS); 359 return true; 360} 361 362bool AliasSetTracker::remove(LoadInst *LI) { 363 unsigned Size = AA.getTargetData().getTypeSize(LI->getType()); 364 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size); 365 if (!AS) return false; 366 remove(*AS); 367 return true; 368} 369 370bool AliasSetTracker::remove(StoreInst *SI) { 371 unsigned Size = AA.getTargetData().getTypeSize(SI->getOperand(0)->getType()); 372 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size); 373 if (!AS) return false; 374 remove(*AS); 375 return true; 376} 377 378bool AliasSetTracker::remove(FreeInst *FI) { 379 AliasSet *AS = findAliasSetForPointer(FI->getOperand(0), ~0); 380 if (!AS) return false; 381 remove(*AS); 382 return true; 383} 384 385bool AliasSetTracker::remove(CallSite CS) { 386 if (Function *F = CS.getCalledFunction()) 387 if (AA.doesNotAccessMemory(F)) 388 return false; // doesn't alias anything 389 390 AliasSet *AS = findAliasSetForCallSite(CS); 391 if (!AS) return false; 392 remove(*AS); 393 return true; 394} 395 396bool AliasSetTracker::remove(Instruction *I) { 397 // Dispatch to one of the other remove methods... 398 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 399 return remove(LI); 400 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 401 return remove(SI); 402 else if (CallInst *CI = dyn_cast<CallInst>(I)) 403 return remove(CI); 404 else if (FreeInst *FI = dyn_cast<FreeInst>(I)) 405 return remove(FI); 406 return true; 407} 408 409 410// deleteValue method - This method is used to remove a pointer value from the 411// AliasSetTracker entirely. It should be used when an instruction is deleted 412// from the program to update the AST. If you don't use this, you would have 413// dangling pointers to deleted instructions. 414// 415void AliasSetTracker::deleteValue(Value *PtrVal) { 416 // Notify the alias analysis implementation that this value is gone. 417 AA.deleteValue(PtrVal); 418 419 // First, look up the PointerRec for this pointer. 420 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal); 421 if (I == PointerMap.end()) return; // Noop 422 423 // If we found one, remove the pointer from the alias set it is in. 424 AliasSet::HashNodePair &PtrValEnt = *I; 425 AliasSet *AS = PtrValEnt.second.getAliasSet(*this); 426 427 // Unlink from the list of values... 428 PtrValEnt.second.removeFromList(); 429 // Stop using the alias set 430 AS->dropRef(*this); 431 PointerMap.erase(I); 432} 433 434// copyValue - This method should be used whenever a preexisting value in the 435// program is copied or cloned, introducing a new value. Note that it is ok for 436// clients that use this method to introduce the same value multiple times: if 437// the tracker already knows about a value, it will ignore the request. 438// 439void AliasSetTracker::copyValue(Value *From, Value *To) { 440 // Notify the alias analysis implementation that this value is copied. 441 AA.copyValue(From, To); 442 443 // First, look up the PointerRec for this pointer. 444 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(From); 445 if (I == PointerMap.end() || !I->second.hasAliasSet()) 446 return; // Noop 447 448 AliasSet::HashNodePair &Entry = getEntryFor(To); 449 if (Entry.second.hasAliasSet()) return; // Already in the tracker! 450 451 // Add it to the alias set it aliases... 452 AliasSet *AS = I->second.getAliasSet(*this); 453 AS->addPointer(*this, Entry, I->second.getSize(), true); 454} 455 456 457 458//===----------------------------------------------------------------------===// 459// AliasSet/AliasSetTracker Printing Support 460//===----------------------------------------------------------------------===// 461 462void AliasSet::print(std::ostream &OS) const { 463 OS << " AliasSet[" << (void*)this << "," << RefCount << "] "; 464 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, "; 465 switch (AccessTy) { 466 case NoModRef: OS << "No access "; break; 467 case Refs : OS << "Ref "; break; 468 case Mods : OS << "Mod "; break; 469 case ModRef : OS << "Mod/Ref "; break; 470 default: assert(0 && "Bad value for AccessTy!"); 471 } 472 if (isVolatile()) OS << "[volatile] "; 473 if (Forward) 474 OS << " forwarding to " << (void*)Forward; 475 476 477 if (begin() != end()) { 478 OS << "Pointers: "; 479 for (iterator I = begin(), E = end(); I != E; ++I) { 480 if (I != begin()) OS << ", "; 481 WriteAsOperand(OS << "(", I.getPointer()); 482 OS << ", " << I.getSize() << ")"; 483 } 484 } 485 if (!CallSites.empty()) { 486 OS << "\n " << CallSites.size() << " Call Sites: "; 487 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) { 488 if (i) OS << ", "; 489 WriteAsOperand(OS, CallSites[i].getCalledValue()); 490 } 491 } 492 OS << "\n"; 493} 494 495void AliasSetTracker::print(std::ostream &OS) const { 496 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for " 497 << PointerMap.size() << " pointer values.\n"; 498 for (const_iterator I = begin(), E = end(); I != E; ++I) 499 I->print(OS); 500 OS << "\n"; 501} 502 503void AliasSet::dump() const { print (std::cerr); } 504void AliasSetTracker::dump() const { print(std::cerr); } 505 506//===----------------------------------------------------------------------===// 507// AliasSetPrinter Pass 508//===----------------------------------------------------------------------===// 509 510namespace { 511 class AliasSetPrinter : public FunctionPass { 512 AliasSetTracker *Tracker; 513 public: 514 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 515 AU.setPreservesAll(); 516 AU.addRequired<AliasAnalysis>(); 517 } 518 519 virtual bool runOnFunction(Function &F) { 520 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>()); 521 522 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) 523 Tracker->add(&*I); 524 return false; 525 } 526 527 /// print - Convert to human readable form 528 virtual void print(std::ostream &OS) const { 529 Tracker->print(OS); 530 } 531 532 virtual void releaseMemory() { 533 delete Tracker; 534 } 535 }; 536 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer", 537 PassInfo::Analysis | PassInfo::Optimization); 538} 539