AliasSetTracker.cpp revision efe30ef790ecec920b48aeacfb98ea4fe5516f01
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/iMemory.h" 17#include "llvm/iOther.h" 18#include "llvm/iTerminators.h" 19#include "llvm/Pass.h" 20#include "llvm/Target/TargetData.h" 21#include "llvm/Assembly/Writer.h" 22#include "llvm/Support/InstIterator.h" 23#include <iostream> 24using namespace llvm; 25 26/// mergeSetIn - Merge the specified alias set into this alias set... 27/// 28void AliasSet::mergeSetIn(AliasSet &AS) { 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 (CallSites.empty()) { // Merge call sites... 37 if (!AS.CallSites.empty()) 38 std::swap(CallSites, AS.CallSites); 39 } else if (!AS.CallSites.empty()) { 40 CallSites.insert(CallSites.end(), AS.CallSites.begin(), AS.CallSites.end()); 41 AS.CallSites.clear(); 42 } 43 44 // FIXME: If AS's refcount is zero, nuke it now... 45 assert(RefCount != 0); 46 47 AS.Forward = this; // Forward across AS now... 48 addRef(); // AS is now pointing to us... 49 50 // Merge the list of constituent pointers... 51 if (AS.PtrList) { 52 *PtrListEnd = AS.PtrList; 53 AS.PtrList->second.setPrevInList(PtrListEnd); 54 PtrListEnd = AS.PtrListEnd; 55 56 AS.PtrList = 0; 57 AS.PtrListEnd = &AS.PtrList; 58 } 59} 60 61void AliasSetTracker::removeAliasSet(AliasSet *AS) { 62 if (AliasSet *Fwd = AS->Forward) { 63 Fwd->dropRef(*this); 64 AS->Forward = 0; 65 } 66 AliasSets.erase(AS); 67} 68 69void AliasSet::removeFromTracker(AliasSetTracker &AST) { 70 assert(RefCount == 0 && "Cannot remove non-dead alias set from tracker!"); 71 AST.removeAliasSet(this); 72} 73 74void AliasSet::addPointer(AliasSetTracker &AST, HashNodePair &Entry, 75 unsigned Size) { 76 assert(!Entry.second.hasAliasSet() && "Entry already in set!"); 77 78 AliasAnalysis &AA = AST.getAliasAnalysis(); 79 80 if (isMustAlias()) // Check to see if we have to downgrade to _may_ alias 81 if (HashNodePair *P = getSomePointer()) { 82 AliasAnalysis::AliasResult Result = 83 AA.alias(P->first, P->second.getSize(), Entry.first, Size); 84 if (Result == AliasAnalysis::MayAlias) 85 AliasTy = MayAlias; 86 else // First entry of must alias must have maximum size! 87 P->second.updateSize(Size); 88 assert(Result != AliasAnalysis::NoAlias && "Cannot be part of must set!"); 89 } 90 91 Entry.second.setAliasSet(this); 92 Entry.second.updateSize(Size); 93 94 // Add it to the end of the list... 95 assert(*PtrListEnd == 0 && "End of list is not null?"); 96 *PtrListEnd = &Entry; 97 PtrListEnd = Entry.second.setPrevInList(PtrListEnd); 98 addRef(); // Entry points to alias set... 99} 100 101void AliasSet::addCallSite(CallSite CS, AliasAnalysis &AA) { 102 CallSites.push_back(CS); 103 104 if (Function *F = CS.getCalledFunction()) { 105 if (AA.doesNotAccessMemory(F)) 106 return; 107 else if (AA.onlyReadsMemory(F)) { 108 AliasTy = MayAlias; 109 AccessTy |= Refs; 110 return; 111 } 112 } 113 114 // FIXME: This should use mod/ref information to make this not suck so bad 115 AliasTy = MayAlias; 116 AccessTy = ModRef; 117} 118 119/// aliasesPointer - Return true if the specified pointer "may" (or must) 120/// alias one of the members in the set. 121/// 122bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size, 123 AliasAnalysis &AA) const { 124 if (AliasTy == MustAlias) { 125 assert(CallSites.empty() && "Illegal must alias set!"); 126 127 // If this is a set of MustAliases, only check to see if the pointer aliases 128 // SOME value in the set... 129 HashNodePair *SomePtr = getSomePointer(); 130 assert(SomePtr && "Empty must-alias set??"); 131 return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size); 132 } 133 134 // If this is a may-alias set, we have to check all of the pointers in the set 135 // to be sure it doesn't alias the set... 136 for (iterator I = begin(), E = end(); I != E; ++I) 137 if (AA.alias(Ptr, Size, I.getPointer(), I.getSize())) 138 return true; 139 140 // Check the call sites list and invoke list... 141 if (!CallSites.empty()) { 142 if (AA.hasNoModRefInfoForCalls()) 143 return true; 144 145 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 146 if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size) 147 != AliasAnalysis::NoModRef) 148 return true; 149 } 150 151 return false; 152} 153 154bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const { 155 if (Function *F = CS.getCalledFunction()) 156 if (AA.doesNotAccessMemory(F)) 157 return false; 158 159 if (AA.hasNoModRefInfoForCalls()) 160 return true; 161 162 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) 163 if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef || 164 AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef) 165 return true; 166 167 for (iterator I = begin(), E = end(); I != E; ++I) 168 if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) != 169 AliasAnalysis::NoModRef) 170 return true; 171 172 return false; 173} 174 175 176/// findAliasSetForPointer - Given a pointer, find the one alias set to put the 177/// instruction referring to the pointer into. If there are multiple alias sets 178/// that may alias the pointer, merge them together and return the unified set. 179/// 180AliasSet *AliasSetTracker::findAliasSetForPointer(const Value *Ptr, 181 unsigned Size) { 182 AliasSet *FoundSet = 0; 183 for (iterator I = begin(), E = end(); I != E; ++I) 184 if (!I->Forward && I->aliasesPointer(Ptr, Size, AA)) { 185 if (FoundSet == 0) { // If this is the first alias set ptr can go into... 186 FoundSet = I; // Remember it. 187 } else { // Otherwise, we must merge the sets... 188 FoundSet->mergeSetIn(*I); // Merge in contents... 189 } 190 } 191 192 return FoundSet; 193} 194 195AliasSet *AliasSetTracker::findAliasSetForCallSite(CallSite CS) { 196 AliasSet *FoundSet = 0; 197 for (iterator I = begin(), E = end(); I != E; ++I) 198 if (!I->Forward && I->aliasesCallSite(CS, AA)) { 199 if (FoundSet == 0) { // If this is the first alias set ptr can go into... 200 FoundSet = I; // Remember it. 201 } else if (!I->Forward) { // Otherwise, we must merge the sets... 202 FoundSet->mergeSetIn(*I); // Merge in contents... 203 } 204 } 205 206 return FoundSet; 207} 208 209 210 211 212/// getAliasSetForPointer - Return the alias set that the specified pointer 213/// lives in... 214AliasSet &AliasSetTracker::getAliasSetForPointer(Value *Pointer, unsigned Size, 215 bool *New) { 216 AliasSet::HashNodePair &Entry = getEntryFor(Pointer); 217 218 // Check to see if the pointer is already known... 219 if (Entry.second.hasAliasSet()) { 220 Entry.second.updateSize(Size); 221 // Return the set! 222 return *Entry.second.getAliasSet(*this)->getForwardedTarget(*this); 223 } else if (AliasSet *AS = findAliasSetForPointer(Pointer, Size)) { 224 // Add it to the alias set it aliases... 225 AS->addPointer(*this, Entry, Size); 226 return *AS; 227 } else { 228 if (New) *New = true; 229 // Otherwise create a new alias set to hold the loaded pointer... 230 AliasSets.push_back(new AliasSet()); 231 AliasSets.back().addPointer(*this, Entry, Size); 232 return AliasSets.back(); 233 } 234} 235 236bool AliasSetTracker::add(Value *Ptr, unsigned Size) { 237 bool NewPtr; 238 addPointer(Ptr, Size, AliasSet::NoModRef, NewPtr); 239 return NewPtr; 240} 241 242 243bool AliasSetTracker::add(LoadInst *LI) { 244 bool NewPtr; 245 AliasSet &AS = addPointer(LI->getOperand(0), 246 AA.getTargetData().getTypeSize(LI->getType()), 247 AliasSet::Refs, NewPtr); 248 if (LI->isVolatile()) AS.setVolatile(); 249 return NewPtr; 250} 251 252bool AliasSetTracker::add(StoreInst *SI) { 253 bool NewPtr; 254 Value *Val = SI->getOperand(0); 255 AliasSet &AS = addPointer(SI->getOperand(1), 256 AA.getTargetData().getTypeSize(Val->getType()), 257 AliasSet::Mods, NewPtr); 258 if (SI->isVolatile()) AS.setVolatile(); 259 return NewPtr; 260} 261 262bool AliasSetTracker::add(FreeInst *FI) { 263 bool NewPtr; 264 AliasSet &AS = addPointer(FI->getOperand(0), ~0, 265 AliasSet::Mods, NewPtr); 266 return NewPtr; 267} 268 269 270bool AliasSetTracker::add(CallSite CS) { 271 bool NewPtr; 272 if (Function *F = CS.getCalledFunction()) 273 if (AA.doesNotAccessMemory(F)) 274 return true; // doesn't alias anything 275 276 AliasSet *AS = findAliasSetForCallSite(CS); 277 if (!AS) { 278 AliasSets.push_back(new AliasSet()); 279 AS = &AliasSets.back(); 280 AS->addCallSite(CS, AA); 281 return true; 282 } else { 283 AS->addCallSite(CS, AA); 284 return false; 285 } 286} 287 288bool AliasSetTracker::add(Instruction *I) { 289 // Dispatch to one of the other add methods... 290 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 291 return add(LI); 292 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 293 return add(SI); 294 else if (CallInst *CI = dyn_cast<CallInst>(I)) 295 return add(CI); 296 else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) 297 return add(II); 298 else if (FreeInst *FI = dyn_cast<FreeInst>(I)) 299 return add(FI); 300 return true; 301} 302 303void AliasSetTracker::add(BasicBlock &BB) { 304 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) 305 add(I); 306} 307 308void AliasSetTracker::add(const AliasSetTracker &AST) { 309 assert(&AA == &AST.AA && 310 "Merging AliasSetTracker objects with different Alias Analyses!"); 311 312 // Loop over all of the alias sets in AST, adding the pointers contained 313 // therein into the current alias sets. This can cause alias sets to be 314 // merged together in the current AST. 315 for (const_iterator I = AST.begin(), E = AST.end(); I != E; ++I) 316 if (!I->Forward) { // Ignore forwarding alias sets 317 AliasSet &AS = const_cast<AliasSet&>(*I); 318 319 // If there are any call sites in the alias set, add them to this AST. 320 for (unsigned i = 0, e = AS.CallSites.size(); i != e; ++i) 321 add(AS.CallSites[i]); 322 323 // Loop over all of the pointers in this alias set... 324 AliasSet::iterator I = AS.begin(), E = AS.end(); 325 bool X; 326 for (; I != E; ++I) 327 addPointer(I.getPointer(), I.getSize(), 328 (AliasSet::AccessType)AS.AccessTy, X); 329 } 330} 331 332/// remove - Remove the specified (potentially non-empty) alias set from the 333/// tracker. 334void AliasSetTracker::remove(AliasSet &AS) { 335 bool SetDead; 336 do { 337 AliasSet::iterator I = AS.begin(); 338 Value *Ptr = I.getPointer(); ++I; 339 340 // deleteValue will delete the set automatically when the last pointer 341 // reference is destroyed. "Predict" when this will happen. 342 SetDead = I == AS.end(); 343 deleteValue(Ptr); // Delete all of the pointers from the set 344 } while (!SetDead); 345} 346 347bool AliasSetTracker::remove(Value *Ptr, unsigned Size) { 348 AliasSet *AS = findAliasSetForPointer(Ptr, Size); 349 if (!AS) return false; 350 remove(*AS); 351 return true; 352} 353 354bool AliasSetTracker::remove(LoadInst *LI) { 355 unsigned Size = AA.getTargetData().getTypeSize(LI->getType()); 356 AliasSet *AS = findAliasSetForPointer(LI->getOperand(0), Size); 357 if (!AS) return false; 358 remove(*AS); 359 return true; 360} 361 362bool AliasSetTracker::remove(StoreInst *SI) { 363 unsigned Size = AA.getTargetData().getTypeSize(SI->getOperand(0)->getType()); 364 AliasSet *AS = findAliasSetForPointer(SI->getOperand(1), Size); 365 if (!AS) return false; 366 remove(*AS); 367 return true; 368} 369 370bool AliasSetTracker::remove(FreeInst *FI) { 371 AliasSet *AS = findAliasSetForPointer(FI->getOperand(0), ~0); 372 if (!AS) return false; 373 remove(*AS); 374 return true; 375} 376 377bool AliasSetTracker::remove(CallSite CS) { 378 if (Function *F = CS.getCalledFunction()) 379 if (AA.doesNotAccessMemory(F)) 380 return false; // doesn't alias anything 381 382 AliasSet *AS = findAliasSetForCallSite(CS); 383 if (!AS) return false; 384 remove(*AS); 385 return true; 386} 387 388bool AliasSetTracker::remove(Instruction *I) { 389 // Dispatch to one of the other remove methods... 390 if (LoadInst *LI = dyn_cast<LoadInst>(I)) 391 return remove(LI); 392 else if (StoreInst *SI = dyn_cast<StoreInst>(I)) 393 return remove(SI); 394 else if (CallInst *CI = dyn_cast<CallInst>(I)) 395 return remove(CI); 396 else if (FreeInst *FI = dyn_cast<FreeInst>(I)) 397 return remove(FI); 398 return true; 399} 400 401 402// deleteValue method - This method is used to remove a pointer value from the 403// AliasSetTracker entirely. It should be used when an instruction is deleted 404// from the program to update the AST. If you don't use this, you would have 405// dangling pointers to deleted instructions. 406// 407void AliasSetTracker::deleteValue(Value *PtrVal) { 408 // First, look up the PointerRec for this pointer... 409 hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal); 410 if (I == PointerMap.end()) return; // Noop 411 412 // If we found one, remove the pointer from the alias set it is in. 413 AliasSet::HashNodePair &PtrValEnt = *I; 414 AliasSet *AS = PtrValEnt.second.getAliasSet(*this); 415 416 // Unlink from the list of values... 417 PtrValEnt.second.removeFromList(); 418 // Stop using the alias set 419 AS->dropRef(*this); 420 PointerMap.erase(I); 421} 422 423 424//===----------------------------------------------------------------------===// 425// AliasSet/AliasSetTracker Printing Support 426//===----------------------------------------------------------------------===// 427 428void AliasSet::print(std::ostream &OS) const { 429 OS << " AliasSet[" << (void*)this << "," << RefCount << "] "; 430 OS << (AliasTy == MustAlias ? "must" : "may ") << " alias, "; 431 switch (AccessTy) { 432 case NoModRef: OS << "No access "; break; 433 case Refs : OS << "Ref "; break; 434 case Mods : OS << "Mod "; break; 435 case ModRef : OS << "Mod/Ref "; break; 436 default: assert(0 && "Bad value for AccessTy!"); 437 } 438 if (isVolatile()) OS << "[volatile] "; 439 if (Forward) 440 OS << " forwarding to " << (void*)Forward; 441 442 443 if (begin() != end()) { 444 OS << "Pointers: "; 445 for (iterator I = begin(), E = end(); I != E; ++I) { 446 if (I != begin()) OS << ", "; 447 WriteAsOperand(OS << "(", I.getPointer()); 448 OS << ", " << I.getSize() << ")"; 449 } 450 } 451 if (!CallSites.empty()) { 452 OS << "\n " << CallSites.size() << " Call Sites: "; 453 for (unsigned i = 0, e = CallSites.size(); i != e; ++i) { 454 if (i) OS << ", "; 455 WriteAsOperand(OS, CallSites[i].getCalledValue()); 456 } 457 } 458 OS << "\n"; 459} 460 461void AliasSetTracker::print(std::ostream &OS) const { 462 OS << "Alias Set Tracker: " << AliasSets.size() << " alias sets for " 463 << PointerMap.size() << " pointer values.\n"; 464 for (const_iterator I = begin(), E = end(); I != E; ++I) 465 I->print(OS); 466 OS << "\n"; 467} 468 469void AliasSet::dump() const { print (std::cerr); } 470void AliasSetTracker::dump() const { print(std::cerr); } 471 472//===----------------------------------------------------------------------===// 473// AliasSetPrinter Pass 474//===----------------------------------------------------------------------===// 475 476namespace { 477 class AliasSetPrinter : public FunctionPass { 478 AliasSetTracker *Tracker; 479 public: 480 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 481 AU.setPreservesAll(); 482 AU.addRequired<AliasAnalysis>(); 483 } 484 485 virtual bool runOnFunction(Function &F) { 486 Tracker = new AliasSetTracker(getAnalysis<AliasAnalysis>()); 487 488 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) 489 Tracker->add(&*I); 490 return false; 491 } 492 493 /// print - Convert to human readable form 494 virtual void print(std::ostream &OS) const { 495 Tracker->print(OS); 496 } 497 498 virtual void releaseMemory() { 499 delete Tracker; 500 } 501 }; 502 RegisterPass<AliasSetPrinter> X("print-alias-sets", "Alias Set Printer", 503 PassInfo::Analysis | PassInfo::Optimization); 504} 505