1 //===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===// 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 a simple N^2 alias analysis accuracy evaluator. 11 // Basically, for each function in the program, it simply queries to see how the 12 // alias analysis implementation answers alias queries between each pair of 13 // pointers in the function. 14 // 15 // This is inspired and adapted from code by: Naveen Neelakantam, Francesco 16 // Spadini, and Wojciech Stryjewski. 17 // 18 //===----------------------------------------------------------------------===// 19 20 #include "llvm/Analysis/Passes.h" 21 #include "llvm/ADT/SetVector.h" 22 #include "llvm/Analysis/AliasAnalysis.h" 23 #include "llvm/IR/Constants.h" 24 #include "llvm/IR/DataLayout.h" 25 #include "llvm/IR/DerivedTypes.h" 26 #include "llvm/IR/Function.h" 27 #include "llvm/IR/Module.h" 28 #include "llvm/IR/InstIterator.h" 29 #include "llvm/IR/Instructions.h" 30 #include "llvm/Pass.h" 31 #include "llvm/Support/CommandLine.h" 32 #include "llvm/Support/Debug.h" 33 #include "llvm/Support/raw_ostream.h" 34 using namespace llvm; 35 36 static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden); 37 38 static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden); 39 static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden); 40 static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden); 41 static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden); 42 43 static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden); 44 static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden); 45 static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden); 46 static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden); 47 48 static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden); 49 50 namespace { 51 class AAEval : public FunctionPass { 52 unsigned NoAliasCount, MayAliasCount, PartialAliasCount, MustAliasCount; 53 unsigned NoModRefCount, ModCount, RefCount, ModRefCount; 54 55 public: 56 static char ID; // Pass identification, replacement for typeid 57 AAEval() : FunctionPass(ID) { 58 initializeAAEvalPass(*PassRegistry::getPassRegistry()); 59 } 60 61 void getAnalysisUsage(AnalysisUsage &AU) const override { 62 AU.addRequired<AAResultsWrapperPass>(); 63 AU.setPreservesAll(); 64 } 65 66 bool doInitialization(Module &M) override { 67 NoAliasCount = MayAliasCount = PartialAliasCount = MustAliasCount = 0; 68 NoModRefCount = ModCount = RefCount = ModRefCount = 0; 69 70 if (PrintAll) { 71 PrintNoAlias = PrintMayAlias = true; 72 PrintPartialAlias = PrintMustAlias = true; 73 PrintNoModRef = PrintMod = PrintRef = PrintModRef = true; 74 } 75 return false; 76 } 77 78 bool runOnFunction(Function &F) override; 79 bool doFinalization(Module &M) override; 80 }; 81 } 82 83 char AAEval::ID = 0; 84 INITIALIZE_PASS_BEGIN(AAEval, "aa-eval", 85 "Exhaustive Alias Analysis Precision Evaluator", false, true) 86 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass) 87 INITIALIZE_PASS_END(AAEval, "aa-eval", 88 "Exhaustive Alias Analysis Precision Evaluator", false, true) 89 90 FunctionPass *llvm::createAAEvalPass() { return new AAEval(); } 91 92 static void PrintResults(const char *Msg, bool P, const Value *V1, 93 const Value *V2, const Module *M) { 94 if (P) { 95 std::string o1, o2; 96 { 97 raw_string_ostream os1(o1), os2(o2); 98 V1->printAsOperand(os1, true, M); 99 V2->printAsOperand(os2, true, M); 100 } 101 102 if (o2 < o1) 103 std::swap(o1, o2); 104 errs() << " " << Msg << ":\t" 105 << o1 << ", " 106 << o2 << "\n"; 107 } 108 } 109 110 static inline void 111 PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr, 112 Module *M) { 113 if (P) { 114 errs() << " " << Msg << ": Ptr: "; 115 Ptr->printAsOperand(errs(), true, M); 116 errs() << "\t<->" << *I << '\n'; 117 } 118 } 119 120 static inline void 121 PrintModRefResults(const char *Msg, bool P, CallSite CSA, CallSite CSB, 122 Module *M) { 123 if (P) { 124 errs() << " " << Msg << ": " << *CSA.getInstruction() 125 << " <-> " << *CSB.getInstruction() << '\n'; 126 } 127 } 128 129 static inline void 130 PrintLoadStoreResults(const char *Msg, bool P, const Value *V1, 131 const Value *V2, const Module *M) { 132 if (P) { 133 errs() << " " << Msg << ": " << *V1 134 << " <-> " << *V2 << '\n'; 135 } 136 } 137 138 static inline bool isInterestingPointer(Value *V) { 139 return V->getType()->isPointerTy() 140 && !isa<ConstantPointerNull>(V); 141 } 142 143 bool AAEval::runOnFunction(Function &F) { 144 const DataLayout &DL = F.getParent()->getDataLayout(); 145 AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults(); 146 147 SetVector<Value *> Pointers; 148 SmallSetVector<CallSite, 16> CallSites; 149 SetVector<Value *> Loads; 150 SetVector<Value *> Stores; 151 152 for (auto &I : F.args()) 153 if (I.getType()->isPointerTy()) // Add all pointer arguments. 154 Pointers.insert(&I); 155 156 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) { 157 if (I->getType()->isPointerTy()) // Add all pointer instructions. 158 Pointers.insert(&*I); 159 if (EvalAAMD && isa<LoadInst>(&*I)) 160 Loads.insert(&*I); 161 if (EvalAAMD && isa<StoreInst>(&*I)) 162 Stores.insert(&*I); 163 Instruction &Inst = *I; 164 if (auto CS = CallSite(&Inst)) { 165 Value *Callee = CS.getCalledValue(); 166 // Skip actual functions for direct function calls. 167 if (!isa<Function>(Callee) && isInterestingPointer(Callee)) 168 Pointers.insert(Callee); 169 // Consider formals. 170 for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end(); 171 AI != AE; ++AI) 172 if (isInterestingPointer(*AI)) 173 Pointers.insert(*AI); 174 CallSites.insert(CS); 175 } else { 176 // Consider all operands. 177 for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end(); 178 OI != OE; ++OI) 179 if (isInterestingPointer(*OI)) 180 Pointers.insert(*OI); 181 } 182 } 183 184 if (PrintNoAlias || PrintMayAlias || PrintPartialAlias || PrintMustAlias || 185 PrintNoModRef || PrintMod || PrintRef || PrintModRef) 186 errs() << "Function: " << F.getName() << ": " << Pointers.size() 187 << " pointers, " << CallSites.size() << " call sites\n"; 188 189 // iterate over the worklist, and run the full (n^2)/2 disambiguations 190 for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end(); 191 I1 != E; ++I1) { 192 uint64_t I1Size = MemoryLocation::UnknownSize; 193 Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType(); 194 if (I1ElTy->isSized()) I1Size = DL.getTypeStoreSize(I1ElTy); 195 196 for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) { 197 uint64_t I2Size = MemoryLocation::UnknownSize; 198 Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType(); 199 if (I2ElTy->isSized()) I2Size = DL.getTypeStoreSize(I2ElTy); 200 201 switch (AA.alias(*I1, I1Size, *I2, I2Size)) { 202 case NoAlias: 203 PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent()); 204 ++NoAliasCount; 205 break; 206 case MayAlias: 207 PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent()); 208 ++MayAliasCount; 209 break; 210 case PartialAlias: 211 PrintResults("PartialAlias", PrintPartialAlias, *I1, *I2, 212 F.getParent()); 213 ++PartialAliasCount; 214 break; 215 case MustAlias: 216 PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent()); 217 ++MustAliasCount; 218 break; 219 } 220 } 221 } 222 223 if (EvalAAMD) { 224 // iterate over all pairs of load, store 225 for (SetVector<Value *>::iterator I1 = Loads.begin(), E = Loads.end(); 226 I1 != E; ++I1) { 227 for (SetVector<Value *>::iterator I2 = Stores.begin(), E2 = Stores.end(); 228 I2 != E2; ++I2) { 229 switch (AA.alias(MemoryLocation::get(cast<LoadInst>(*I1)), 230 MemoryLocation::get(cast<StoreInst>(*I2)))) { 231 case NoAlias: 232 PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2, 233 F.getParent()); 234 ++NoAliasCount; 235 break; 236 case MayAlias: 237 PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2, 238 F.getParent()); 239 ++MayAliasCount; 240 break; 241 case PartialAlias: 242 PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2, 243 F.getParent()); 244 ++PartialAliasCount; 245 break; 246 case MustAlias: 247 PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2, 248 F.getParent()); 249 ++MustAliasCount; 250 break; 251 } 252 } 253 } 254 255 // iterate over all pairs of store, store 256 for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end(); 257 I1 != E; ++I1) { 258 for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) { 259 switch (AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)), 260 MemoryLocation::get(cast<StoreInst>(*I2)))) { 261 case NoAlias: 262 PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2, 263 F.getParent()); 264 ++NoAliasCount; 265 break; 266 case MayAlias: 267 PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2, 268 F.getParent()); 269 ++MayAliasCount; 270 break; 271 case PartialAlias: 272 PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2, 273 F.getParent()); 274 ++PartialAliasCount; 275 break; 276 case MustAlias: 277 PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2, 278 F.getParent()); 279 ++MustAliasCount; 280 break; 281 } 282 } 283 } 284 } 285 286 // Mod/ref alias analysis: compare all pairs of calls and values 287 for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) { 288 Instruction *I = C->getInstruction(); 289 290 for (SetVector<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end(); 291 V != Ve; ++V) { 292 uint64_t Size = MemoryLocation::UnknownSize; 293 Type *ElTy = cast<PointerType>((*V)->getType())->getElementType(); 294 if (ElTy->isSized()) Size = DL.getTypeStoreSize(ElTy); 295 296 switch (AA.getModRefInfo(*C, *V, Size)) { 297 case MRI_NoModRef: 298 PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent()); 299 ++NoModRefCount; 300 break; 301 case MRI_Mod: 302 PrintModRefResults("Just Mod", PrintMod, I, *V, F.getParent()); 303 ++ModCount; 304 break; 305 case MRI_Ref: 306 PrintModRefResults("Just Ref", PrintRef, I, *V, F.getParent()); 307 ++RefCount; 308 break; 309 case MRI_ModRef: 310 PrintModRefResults("Both ModRef", PrintModRef, I, *V, F.getParent()); 311 ++ModRefCount; 312 break; 313 } 314 } 315 } 316 317 // Mod/ref alias analysis: compare all pairs of calls 318 for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) { 319 for (auto D = CallSites.begin(); D != Ce; ++D) { 320 if (D == C) 321 continue; 322 switch (AA.getModRefInfo(*C, *D)) { 323 case MRI_NoModRef: 324 PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent()); 325 ++NoModRefCount; 326 break; 327 case MRI_Mod: 328 PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent()); 329 ++ModCount; 330 break; 331 case MRI_Ref: 332 PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent()); 333 ++RefCount; 334 break; 335 case MRI_ModRef: 336 PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent()); 337 ++ModRefCount; 338 break; 339 } 340 } 341 } 342 343 return false; 344 } 345 346 static void PrintPercent(unsigned Num, unsigned Sum) { 347 errs() << "(" << Num*100ULL/Sum << "." 348 << ((Num*1000ULL/Sum) % 10) << "%)\n"; 349 } 350 351 bool AAEval::doFinalization(Module &M) { 352 unsigned AliasSum = 353 NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount; 354 errs() << "===== Alias Analysis Evaluator Report =====\n"; 355 if (AliasSum == 0) { 356 errs() << " Alias Analysis Evaluator Summary: No pointers!\n"; 357 } else { 358 errs() << " " << AliasSum << " Total Alias Queries Performed\n"; 359 errs() << " " << NoAliasCount << " no alias responses "; 360 PrintPercent(NoAliasCount, AliasSum); 361 errs() << " " << MayAliasCount << " may alias responses "; 362 PrintPercent(MayAliasCount, AliasSum); 363 errs() << " " << PartialAliasCount << " partial alias responses "; 364 PrintPercent(PartialAliasCount, AliasSum); 365 errs() << " " << MustAliasCount << " must alias responses "; 366 PrintPercent(MustAliasCount, AliasSum); 367 errs() << " Alias Analysis Evaluator Pointer Alias Summary: " 368 << NoAliasCount * 100 / AliasSum << "%/" 369 << MayAliasCount * 100 / AliasSum << "%/" 370 << PartialAliasCount * 100 / AliasSum << "%/" 371 << MustAliasCount * 100 / AliasSum << "%\n"; 372 } 373 374 // Display the summary for mod/ref analysis 375 unsigned ModRefSum = NoModRefCount + ModCount + RefCount + ModRefCount; 376 if (ModRefSum == 0) { 377 errs() << " Alias Analysis Mod/Ref Evaluator Summary: no " 378 "mod/ref!\n"; 379 } else { 380 errs() << " " << ModRefSum << " Total ModRef Queries Performed\n"; 381 errs() << " " << NoModRefCount << " no mod/ref responses "; 382 PrintPercent(NoModRefCount, ModRefSum); 383 errs() << " " << ModCount << " mod responses "; 384 PrintPercent(ModCount, ModRefSum); 385 errs() << " " << RefCount << " ref responses "; 386 PrintPercent(RefCount, ModRefSum); 387 errs() << " " << ModRefCount << " mod & ref responses "; 388 PrintPercent(ModRefCount, ModRefSum); 389 errs() << " Alias Analysis Evaluator Mod/Ref Summary: " 390 << NoModRefCount * 100 / ModRefSum << "%/" 391 << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum 392 << "%/" << ModRefCount * 100 / ModRefSum << "%\n"; 393 } 394 395 return false; 396 } 397
