lib/Analysis/AliasAnalysisEvaluator.cpp

   1 //===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Analysis/AliasAnalysisEvaluator.h"
  10 #include "llvm/ADT/SetVector.h"
  11 #include "llvm/Analysis/AliasAnalysis.h"
  12 #include "llvm/IR/Constants.h"
  13 #include "llvm/IR/DataLayout.h"
  14 #include "llvm/IR/DerivedTypes.h"
  15 #include "llvm/IR/Function.h"
  16 #include "llvm/IR/InstIterator.h"
  17 #include "llvm/IR/Instructions.h"
  18 #include "llvm/IR/Module.h"
  19 #include "llvm/Pass.h"
  20 #include "llvm/Support/CommandLine.h"
  21 #include "llvm/Support/Debug.h"
  22 #include "llvm/Support/raw_ostream.h"
  23 using namespace llvm;
  24
  25 static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
  26
  27 static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
  28 static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
  29 static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden);
  30 static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
  31
  32 static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
  33 static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
  34 static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
  35 static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
  36 static cl::opt<bool> PrintMust("print-must", cl::ReallyHidden);
  37 static cl::opt<bool> PrintMustRef("print-mustref", cl::ReallyHidden);
  38 static cl::opt<bool> PrintMustMod("print-mustmod", cl::ReallyHidden);
  39 static cl::opt<bool> PrintMustModRef("print-mustmodref", cl::ReallyHidden);
  40
  41 static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden);
  42
  43 static void PrintResults(AliasResult AR, bool P, const Value *V1,
  44                          const Value *V2, const Module *M) {
  45   if (PrintAll || P) {
  46     std::string o1, o2;
  47     {
  48       raw_string_ostream os1(o1), os2(o2);
  49       V1->printAsOperand(os1, true, M);
  50       V2->printAsOperand(os2, true, M);
  51     }
  52
  53     if (o2 < o1)
  54       std::swap(o1, o2);
  55     errs() << "  " << AR << ":\t" << o1 << ", " << o2 << "\n";
  56   }
  57 }
  58
  59 static inline void PrintModRefResults(const char *Msg, bool P, Instruction *I,
  60                                       Value *Ptr, Module *M) {
  61   if (PrintAll || P) {
  62     errs() << "  " << Msg << ":  Ptr: ";
  63     Ptr->printAsOperand(errs(), true, M);
  64     errs() << "\t<->" << *I << '\n';
  65   }
  66 }
  67
  68 static inline void PrintModRefResults(const char *Msg, bool P, CallBase *CallA,
  69                                       CallBase *CallB, Module *M) {
  70   if (PrintAll || P) {
  71     errs() << "  " << Msg << ": " << *CallA << " <-> " << *CallB << '\n';
  72   }
  73 }
  74
  75 static inline void PrintLoadStoreResults(AliasResult AR, bool P,
  76                                          const Value *V1, const Value *V2,
  77                                          const Module *M) {
  78   if (PrintAll || P) {
  79     errs() << "  " << AR << ": " << *V1 << " <-> " << *V2 << '\n';
  80   }
  81 }
  82
  83 static inline bool isInterestingPointer(Value *V) {
  84   return V->getType()->isPointerTy()
  85       && !isa<ConstantPointerNull>(V);
  86 }
  87
  88 PreservedAnalyses AAEvaluator::run(Function &F, FunctionAnalysisManager &AM) {
  89   runInternal(F, AM.getResult<AAManager>(F));
  90   return PreservedAnalyses::all();
  91 }
  92
  93 void AAEvaluator::runInternal(Function &F, AAResults &AA) {
  94   const DataLayout &DL = F.getParent()->getDataLayout();
  95
  96   ++FunctionCount;
  97
  98   SetVector<Value *> Pointers;
  99   SmallSetVector<CallBase *, 16> Calls;
 100   SetVector<Value *> Loads;
 101   SetVector<Value *> Stores;
 102
 103   for (auto &I : F.args())
 104     if (I.getType()->isPointerTy())    // Add all pointer arguments.
 105       Pointers.insert(&I);
 106
 107   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
 108     if (I->getType()->isPointerTy()) // Add all pointer instructions.
 109       Pointers.insert(&*I);
 110     if (EvalAAMD && isa<LoadInst>(&*I))
 111       Loads.insert(&*I);
 112     if (EvalAAMD && isa<StoreInst>(&*I))
 113       Stores.insert(&*I);
 114     Instruction &Inst = *I;
 115     if (auto *Call = dyn_cast<CallBase>(&Inst)) {
 116       Value *Callee = Call->getCalledValue();
 117       // Skip actual functions for direct function calls.
 118       if (!isa<Function>(Callee) && isInterestingPointer(Callee))
 119         Pointers.insert(Callee);
 120       // Consider formals.
 121       for (Use &DataOp : Call->data_ops())
 122         if (isInterestingPointer(DataOp))
 123           Pointers.insert(DataOp);
 124       Calls.insert(Call);
 125     } else {
 126       // Consider all operands.
 127       for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
 128            OI != OE; ++OI)
 129         if (isInterestingPointer(*OI))
 130           Pointers.insert(*OI);
 131     }
 132   }
 133
 134   if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
 135       PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
 136     errs() << "Function: " << F.getName() << ": " << Pointers.size()
 137            << " pointers, " << Calls.size() << " call sites\n";
 138
 139   // iterate over the worklist, and run the full (n^2)/2 disambiguations
 140   for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
 141        I1 != E; ++I1) {
 142     auto I1Size = LocationSize::unknown();
 143     Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
 144     if (I1ElTy->isSized())
 145       I1Size = LocationSize::precise(DL.getTypeStoreSize(I1ElTy));
 146
 147     for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
 148       auto I2Size = LocationSize::unknown();
 149       Type *I2ElTy = cast<PointerType>((*I2)->getType())->getElementType();
 150       if (I2ElTy->isSized())
 151         I2Size = LocationSize::precise(DL.getTypeStoreSize(I2ElTy));
 152
 153       AliasResult AR = AA.alias(*I1, I1Size, *I2, I2Size);
 154       switch (AR) {
 155       case NoAlias:
 156         PrintResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
 157         ++NoAliasCount;
 158         break;
 159       case MayAlias:
 160         PrintResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
 161         ++MayAliasCount;
 162         break;
 163       case PartialAlias:
 164         PrintResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
 165         ++PartialAliasCount;
 166         break;
 167       case MustAlias:
 168         PrintResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
 169         ++MustAliasCount;
 170         break;
 171       }
 172     }
 173   }
 174
 175   if (EvalAAMD) {
 176     // iterate over all pairs of load, store
 177     for (Value *Load : Loads) {
 178       for (Value *Store : Stores) {
 179         AliasResult AR = AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
 180                                   MemoryLocation::get(cast<StoreInst>(Store)));
 181         switch (AR) {
 182         case NoAlias:
 183           PrintLoadStoreResults(AR, PrintNoAlias, Load, Store, F.getParent());
 184           ++NoAliasCount;
 185           break;
 186         case MayAlias:
 187           PrintLoadStoreResults(AR, PrintMayAlias, Load, Store, F.getParent());
 188           ++MayAliasCount;
 189           break;
 190         case PartialAlias:
 191           PrintLoadStoreResults(AR, PrintPartialAlias, Load, Store, F.getParent());
 192           ++PartialAliasCount;
 193           break;
 194         case MustAlias:
 195           PrintLoadStoreResults(AR, PrintMustAlias, Load, Store, F.getParent());
 196           ++MustAliasCount;
 197           break;
 198         }
 199       }
 200     }
 201
 202     // iterate over all pairs of store, store
 203     for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
 204          I1 != E; ++I1) {
 205       for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
 206         AliasResult AR = AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
 207                                   MemoryLocation::get(cast<StoreInst>(*I2)));
 208         switch (AR) {
 209         case NoAlias:
 210           PrintLoadStoreResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
 211           ++NoAliasCount;
 212           break;
 213         case MayAlias:
 214           PrintLoadStoreResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
 215           ++MayAliasCount;
 216           break;
 217         case PartialAlias:
 218           PrintLoadStoreResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
 219           ++PartialAliasCount;
 220           break;
 221         case MustAlias:
 222           PrintLoadStoreResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
 223           ++MustAliasCount;
 224           break;
 225         }
 226       }
 227     }
 228   }
 229
 230   // Mod/ref alias analysis: compare all pairs of calls and values
 231   for (CallBase *Call : Calls) {
 232     for (auto Pointer : Pointers) {
 233       auto Size = LocationSize::unknown();
 234       Type *ElTy = cast<PointerType>(Pointer->getType())->getElementType();
 235       if (ElTy->isSized())
 236         Size = LocationSize::precise(DL.getTypeStoreSize(ElTy));
 237
 238       switch (AA.getModRefInfo(Call, Pointer, Size)) {
 239       case ModRefInfo::NoModRef:
 240         PrintModRefResults("NoModRef", PrintNoModRef, Call, Pointer,
 241                            F.getParent());
 242         ++NoModRefCount;
 243         break;
 244       case ModRefInfo::Mod:
 245         PrintModRefResults("Just Mod", PrintMod, Call, Pointer, F.getParent());
 246         ++ModCount;
 247         break;
 248       case ModRefInfo::Ref:
 249         PrintModRefResults("Just Ref", PrintRef, Call, Pointer, F.getParent());
 250         ++RefCount;
 251         break;
 252       case ModRefInfo::ModRef:
 253         PrintModRefResults("Both ModRef", PrintModRef, Call, Pointer,
 254                            F.getParent());
 255         ++ModRefCount;
 256         break;
 257       case ModRefInfo::Must:
 258         PrintModRefResults("Must", PrintMust, Call, Pointer, F.getParent());
 259         ++MustCount;
 260         break;
 261       case ModRefInfo::MustMod:
 262         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, Call, Pointer,
 263                            F.getParent());
 264         ++MustModCount;
 265         break;
 266       case ModRefInfo::MustRef:
 267         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, Call, Pointer,
 268                            F.getParent());
 269         ++MustRefCount;
 270         break;
 271       case ModRefInfo::MustModRef:
 272         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, Call,
 273                            Pointer, F.getParent());
 274         ++MustModRefCount;
 275         break;
 276       }
 277     }
 278   }
 279
 280   // Mod/ref alias analysis: compare all pairs of calls
 281   for (CallBase *CallA : Calls) {
 282     for (CallBase *CallB : Calls) {
 283       if (CallA == CallB)
 284         continue;
 285       switch (AA.getModRefInfo(CallA, CallB)) {
 286       case ModRefInfo::NoModRef:
 287         PrintModRefResults("NoModRef", PrintNoModRef, CallA, CallB,
 288                            F.getParent());
 289         ++NoModRefCount;
 290         break;
 291       case ModRefInfo::Mod:
 292         PrintModRefResults("Just Mod", PrintMod, CallA, CallB, F.getParent());
 293         ++ModCount;
 294         break;
 295       case ModRefInfo::Ref:
 296         PrintModRefResults("Just Ref", PrintRef, CallA, CallB, F.getParent());
 297         ++RefCount;
 298         break;
 299       case ModRefInfo::ModRef:
 300         PrintModRefResults("Both ModRef", PrintModRef, CallA, CallB,
 301                            F.getParent());
 302         ++ModRefCount;
 303         break;
 304       case ModRefInfo::Must:
 305         PrintModRefResults("Must", PrintMust, CallA, CallB, F.getParent());
 306         ++MustCount;
 307         break;
 308       case ModRefInfo::MustMod:
 309         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, CallA, CallB,
 310                            F.getParent());
 311         ++MustModCount;
 312         break;
 313       case ModRefInfo::MustRef:
 314         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, CallA, CallB,
 315                            F.getParent());
 316         ++MustRefCount;
 317         break;
 318       case ModRefInfo::MustModRef:
 319         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, CallA,
 320                            CallB, F.getParent());
 321         ++MustModRefCount;
 322         break;
 323       }
 324     }
 325   }
 326 }
 327
 328 static void PrintPercent(int64_t Num, int64_t Sum) {
 329   errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
 330          << "%)\n";
 331 }
 332
 333 AAEvaluator::~AAEvaluator() {
 334   if (FunctionCount == 0)
 335     return;
 336
 337   int64_t AliasSum =
 338       NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
 339   errs() << "===== Alias Analysis Evaluator Report =====\n";
 340   if (AliasSum == 0) {
 341     errs() << "  Alias Analysis Evaluator Summary: No pointers!\n";
 342   } else {
 343     errs() << "  " << AliasSum << " Total Alias Queries Performed\n";
 344     errs() << "  " << NoAliasCount << " no alias responses ";
 345     PrintPercent(NoAliasCount, AliasSum);
 346     errs() << "  " << MayAliasCount << " may alias responses ";
 347     PrintPercent(MayAliasCount, AliasSum);
 348     errs() << "  " << PartialAliasCount << " partial alias responses ";
 349     PrintPercent(PartialAliasCount, AliasSum);
 350     errs() << "  " << MustAliasCount << " must alias responses ";
 351     PrintPercent(MustAliasCount, AliasSum);
 352     errs() << "  Alias Analysis Evaluator Pointer Alias Summary: "
 353            << NoAliasCount * 100 / AliasSum << "%/"
 354            << MayAliasCount * 100 / AliasSum << "%/"
 355            << PartialAliasCount * 100 / AliasSum << "%/"
 356            << MustAliasCount * 100 / AliasSum << "%\n";
 357   }
 358
 359   // Display the summary for mod/ref analysis
 360   int64_t ModRefSum = NoModRefCount + RefCount + ModCount + ModRefCount +
 361                       MustCount + MustRefCount + MustModCount + MustModRefCount;
 362   if (ModRefSum == 0) {
 363     errs() << "  Alias Analysis Mod/Ref Evaluator Summary: no "
 364               "mod/ref!\n";
 365   } else {
 366     errs() << "  " << ModRefSum << " Total ModRef Queries Performed\n";
 367     errs() << "  " << NoModRefCount << " no mod/ref responses ";
 368     PrintPercent(NoModRefCount, ModRefSum);
 369     errs() << "  " << ModCount << " mod responses ";
 370     PrintPercent(ModCount, ModRefSum);
 371     errs() << "  " << RefCount << " ref responses ";
 372     PrintPercent(RefCount, ModRefSum);
 373     errs() << "  " << ModRefCount << " mod & ref responses ";
 374     PrintPercent(ModRefCount, ModRefSum);
 375     errs() << "  " << MustCount << " must responses ";
 376     PrintPercent(MustCount, ModRefSum);
 377     errs() << "  " << MustModCount << " must mod responses ";
 378     PrintPercent(MustModCount, ModRefSum);
 379     errs() << "  " << MustRefCount << " must ref responses ";
 380     PrintPercent(MustRefCount, ModRefSum);
 381     errs() << "  " << MustModRefCount << " must mod & ref responses ";
 382     PrintPercent(MustModRefCount, ModRefSum);
 383     errs() << "  Alias Analysis Evaluator Mod/Ref Summary: "
 384            << NoModRefCount * 100 / ModRefSum << "%/"
 385            << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
 386            << "%/" << ModRefCount * 100 / ModRefSum << "%/"
 387            << MustCount * 100 / ModRefSum << "%/"
 388            << MustRefCount * 100 / ModRefSum << "%/"
 389            << MustModCount * 100 / ModRefSum << "%/"
 390            << MustModRefCount * 100 / ModRefSum << "%\n";
 391   }
 392 }
 393
 394 namespace llvm {
 395 class AAEvalLegacyPass : public FunctionPass {
 396   std::unique_ptr<AAEvaluator> P;
 397
 398 public:
 399   static char ID; // Pass identification, replacement for typeid
 400   AAEvalLegacyPass() : FunctionPass(ID) {
 401     initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
 402   }
 403
 404   void getAnalysisUsage(AnalysisUsage &AU) const override {
 405     AU.addRequired<AAResultsWrapperPass>();
 406     AU.setPreservesAll();
 407   }
 408
 409   bool doInitialization(Module &M) override {
 410     P.reset(new AAEvaluator());
 411     return false;
 412   }
 413
 414   bool runOnFunction(Function &F) override {
 415     P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
 416     return false;
 417   }
 418   bool doFinalization(Module &M) override {
 419     P.reset();
 420     return false;
 421   }
 422 };
 423 }
 424
 425 char AAEvalLegacyPass::ID = 0;
 426 INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
 427                       "Exhaustive Alias Analysis Precision Evaluator", false,
 428                       true)
 429 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
 430 INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
 431                     "Exhaustive Alias Analysis Precision Evaluator", false,
 432                     true)
 433
 434 FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }