llvm/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/InitializePasses.h"
  20 #include "llvm/Pass.h"
  21 #include "llvm/Support/CommandLine.h"
  22 #include "llvm/Support/Debug.h"
  23 #include "llvm/Support/raw_ostream.h"
  24 using namespace llvm;
  25
  26 static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
  27
  28 static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
  29 static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
  30 static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden);
  31 static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
  32
  33 static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
  34 static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
  35 static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
  36 static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
  37 static cl::opt<bool> PrintMust("print-must", cl::ReallyHidden);
  38 static cl::opt<bool> PrintMustRef("print-mustref", cl::ReallyHidden);
  39 static cl::opt<bool> PrintMustMod("print-mustmod", cl::ReallyHidden);
  40 static cl::opt<bool> PrintMustModRef("print-mustmodref", cl::ReallyHidden);
  41
  42 static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden);
  43
  44 static void PrintResults(AliasResult AR, bool P, const Value *V1,
  45                          const Value *V2, const Module *M) {
  46   if (PrintAll || P) {
  47     std::string o1, o2;
  48     {
  49       raw_string_ostream os1(o1), os2(o2);
  50       V1->printAsOperand(os1, true, M);
  51       V2->printAsOperand(os2, true, M);
  52     }
  53
  54     if (o2 < o1) {
  55       std::swap(o1, o2);
  56       // Change offset sign for the local AR, for printing only.
  57       AR.swap();
  58     }
  59     errs() << "  " << AR << ":\t" << o1 << ", " << o2 << "\n";
  60   }
  61 }
  62
  63 static inline void PrintModRefResults(const char *Msg, bool P, Instruction *I,
  64                                       Value *Ptr, Module *M) {
  65   if (PrintAll || P) {
  66     errs() << "  " << Msg << ":  Ptr: ";
  67     Ptr->printAsOperand(errs(), true, M);
  68     errs() << "\t<->" << *I << '\n';
  69   }
  70 }
  71
  72 static inline void PrintModRefResults(const char *Msg, bool P, CallBase *CallA,
  73                                       CallBase *CallB, Module *M) {
  74   if (PrintAll || P) {
  75     errs() << "  " << Msg << ": " << *CallA << " <-> " << *CallB << '\n';
  76   }
  77 }
  78
  79 static inline void PrintLoadStoreResults(AliasResult AR, bool P,
  80                                          const Value *V1, const Value *V2,
  81                                          const Module *M) {
  82   if (PrintAll || P) {
  83     errs() << "  " << AR << ": " << *V1 << " <-> " << *V2 << '\n';
  84   }
  85 }
  86
  87 static inline bool isInterestingPointer(Value *V) {
  88   return V->getType()->isPointerTy()
  89       && !isa<ConstantPointerNull>(V);
  90 }
  91
  92 PreservedAnalyses AAEvaluator::run(Function &F, FunctionAnalysisManager &AM) {
  93   runInternal(F, AM.getResult<AAManager>(F));
  94   return PreservedAnalyses::all();
  95 }
  96
  97 void AAEvaluator::runInternal(Function &F, AAResults &AA) {
  98   const DataLayout &DL = F.getParent()->getDataLayout();
  99
 100   ++FunctionCount;
 101
 102   SetVector<Value *> Pointers;
 103   SmallSetVector<CallBase *, 16> Calls;
 104   SetVector<Value *> Loads;
 105   SetVector<Value *> Stores;
 106
 107   for (auto &I : F.args())
 108     if (I.getType()->isPointerTy())    // Add all pointer arguments.
 109       Pointers.insert(&I);
 110
 111   for (Instruction &Inst : instructions(F)) {
 112     if (Inst.getType()->isPointerTy()) // Add all pointer instructions.
 113       Pointers.insert(&Inst);
 114     if (EvalAAMD && isa<LoadInst>(&Inst))
 115       Loads.insert(&Inst);
 116     if (EvalAAMD && isa<StoreInst>(&Inst))
 117       Stores.insert(&Inst);
 118     if (auto *Call = dyn_cast<CallBase>(&Inst)) {
 119       Value *Callee = Call->getCalledOperand();
 120       // Skip actual functions for direct function calls.
 121       if (!isa<Function>(Callee) && isInterestingPointer(Callee))
 122         Pointers.insert(Callee);
 123       // Consider formals.
 124       for (Use &DataOp : Call->data_ops())
 125         if (isInterestingPointer(DataOp))
 126           Pointers.insert(DataOp);
 127       Calls.insert(Call);
 128     } else {
 129       // Consider all operands.
 130       for (Use &Op : Inst.operands())
 131         if (isInterestingPointer(Op))
 132           Pointers.insert(Op);
 133     }
 134   }
 135
 136   if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
 137       PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
 138     errs() << "Function: " << F.getName() << ": " << Pointers.size()
 139            << " pointers, " << Calls.size() << " call sites\n";
 140
 141   // iterate over the worklist, and run the full (n^2)/2 disambiguations
 142   for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
 143        I1 != E; ++I1) {
 144     auto I1Size = LocationSize::afterPointer();
 145     Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
 146     if (I1ElTy->isSized())
 147       I1Size = LocationSize::precise(DL.getTypeStoreSize(I1ElTy));
 148
 149     for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
 150       auto I2Size = LocationSize::afterPointer();
 151       Type *I2ElTy = cast<PointerType>((*I2)->getType())->getElementType();
 152       if (I2ElTy->isSized())
 153         I2Size = LocationSize::precise(DL.getTypeStoreSize(I2ElTy));
 154
 155       AliasResult AR = AA.alias(*I1, I1Size, *I2, I2Size);
 156       switch (AR) {
 157       case AliasResult::NoAlias:
 158         PrintResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
 159         ++NoAliasCount;
 160         break;
 161       case AliasResult::MayAlias:
 162         PrintResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
 163         ++MayAliasCount;
 164         break;
 165       case AliasResult::PartialAlias:
 166         PrintResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
 167         ++PartialAliasCount;
 168         break;
 169       case AliasResult::MustAlias:
 170         PrintResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
 171         ++MustAliasCount;
 172         break;
 173       }
 174     }
 175   }
 176
 177   if (EvalAAMD) {
 178     // iterate over all pairs of load, store
 179     for (Value *Load : Loads) {
 180       for (Value *Store : Stores) {
 181         AliasResult AR = AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
 182                                   MemoryLocation::get(cast<StoreInst>(Store)));
 183         switch (AR) {
 184         case AliasResult::NoAlias:
 185           PrintLoadStoreResults(AR, PrintNoAlias, Load, Store, F.getParent());
 186           ++NoAliasCount;
 187           break;
 188         case AliasResult::MayAlias:
 189           PrintLoadStoreResults(AR, PrintMayAlias, Load, Store, F.getParent());
 190           ++MayAliasCount;
 191           break;
 192         case AliasResult::PartialAlias:
 193           PrintLoadStoreResults(AR, PrintPartialAlias, Load, Store, F.getParent());
 194           ++PartialAliasCount;
 195           break;
 196         case AliasResult::MustAlias:
 197           PrintLoadStoreResults(AR, PrintMustAlias, Load, Store, F.getParent());
 198           ++MustAliasCount;
 199           break;
 200         }
 201       }
 202     }
 203
 204     // iterate over all pairs of store, store
 205     for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
 206          I1 != E; ++I1) {
 207       for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
 208         AliasResult AR = AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
 209                                   MemoryLocation::get(cast<StoreInst>(*I2)));
 210         switch (AR) {
 211         case AliasResult::NoAlias:
 212           PrintLoadStoreResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
 213           ++NoAliasCount;
 214           break;
 215         case AliasResult::MayAlias:
 216           PrintLoadStoreResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
 217           ++MayAliasCount;
 218           break;
 219         case AliasResult::PartialAlias:
 220           PrintLoadStoreResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
 221           ++PartialAliasCount;
 222           break;
 223         case AliasResult::MustAlias:
 224           PrintLoadStoreResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
 225           ++MustAliasCount;
 226           break;
 227         }
 228       }
 229     }
 230   }
 231
 232   // Mod/ref alias analysis: compare all pairs of calls and values
 233   for (CallBase *Call : Calls) {
 234     for (auto Pointer : Pointers) {
 235       auto Size = LocationSize::afterPointer();
 236       Type *ElTy = cast<PointerType>(Pointer->getType())->getElementType();
 237       if (ElTy->isSized())
 238         Size = LocationSize::precise(DL.getTypeStoreSize(ElTy));
 239
 240       switch (AA.getModRefInfo(Call, Pointer, Size)) {
 241       case ModRefInfo::NoModRef:
 242         PrintModRefResults("NoModRef", PrintNoModRef, Call, Pointer,
 243                            F.getParent());
 244         ++NoModRefCount;
 245         break;
 246       case ModRefInfo::Mod:
 247         PrintModRefResults("Just Mod", PrintMod, Call, Pointer, F.getParent());
 248         ++ModCount;
 249         break;
 250       case ModRefInfo::Ref:
 251         PrintModRefResults("Just Ref", PrintRef, Call, Pointer, F.getParent());
 252         ++RefCount;
 253         break;
 254       case ModRefInfo::ModRef:
 255         PrintModRefResults("Both ModRef", PrintModRef, Call, Pointer,
 256                            F.getParent());
 257         ++ModRefCount;
 258         break;
 259       case ModRefInfo::Must:
 260         PrintModRefResults("Must", PrintMust, Call, Pointer, F.getParent());
 261         ++MustCount;
 262         break;
 263       case ModRefInfo::MustMod:
 264         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, Call, Pointer,
 265                            F.getParent());
 266         ++MustModCount;
 267         break;
 268       case ModRefInfo::MustRef:
 269         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, Call, Pointer,
 270                            F.getParent());
 271         ++MustRefCount;
 272         break;
 273       case ModRefInfo::MustModRef:
 274         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, Call,
 275                            Pointer, F.getParent());
 276         ++MustModRefCount;
 277         break;
 278       }
 279     }
 280   }
 281
 282   // Mod/ref alias analysis: compare all pairs of calls
 283   for (CallBase *CallA : Calls) {
 284     for (CallBase *CallB : Calls) {
 285       if (CallA == CallB)
 286         continue;
 287       switch (AA.getModRefInfo(CallA, CallB)) {
 288       case ModRefInfo::NoModRef:
 289         PrintModRefResults("NoModRef", PrintNoModRef, CallA, CallB,
 290                            F.getParent());
 291         ++NoModRefCount;
 292         break;
 293       case ModRefInfo::Mod:
 294         PrintModRefResults("Just Mod", PrintMod, CallA, CallB, F.getParent());
 295         ++ModCount;
 296         break;
 297       case ModRefInfo::Ref:
 298         PrintModRefResults("Just Ref", PrintRef, CallA, CallB, F.getParent());
 299         ++RefCount;
 300         break;
 301       case ModRefInfo::ModRef:
 302         PrintModRefResults("Both ModRef", PrintModRef, CallA, CallB,
 303                            F.getParent());
 304         ++ModRefCount;
 305         break;
 306       case ModRefInfo::Must:
 307         PrintModRefResults("Must", PrintMust, CallA, CallB, F.getParent());
 308         ++MustCount;
 309         break;
 310       case ModRefInfo::MustMod:
 311         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, CallA, CallB,
 312                            F.getParent());
 313         ++MustModCount;
 314         break;
 315       case ModRefInfo::MustRef:
 316         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, CallA, CallB,
 317                            F.getParent());
 318         ++MustRefCount;
 319         break;
 320       case ModRefInfo::MustModRef:
 321         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, CallA,
 322                            CallB, F.getParent());
 323         ++MustModRefCount;
 324         break;
 325       }
 326     }
 327   }
 328 }
 329
 330 static void PrintPercent(int64_t Num, int64_t Sum) {
 331   errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
 332          << "%)\n";
 333 }
 334
 335 AAEvaluator::~AAEvaluator() {
 336   if (FunctionCount == 0)
 337     return;
 338
 339   int64_t AliasSum =
 340       NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
 341   errs() << "===== Alias Analysis Evaluator Report =====\n";
 342   if (AliasSum == 0) {
 343     errs() << "  Alias Analysis Evaluator Summary: No pointers!\n";
 344   } else {
 345     errs() << "  " << AliasSum << " Total Alias Queries Performed\n";
 346     errs() << "  " << NoAliasCount << " no alias responses ";
 347     PrintPercent(NoAliasCount, AliasSum);
 348     errs() << "  " << MayAliasCount << " may alias responses ";
 349     PrintPercent(MayAliasCount, AliasSum);
 350     errs() << "  " << PartialAliasCount << " partial alias responses ";
 351     PrintPercent(PartialAliasCount, AliasSum);
 352     errs() << "  " << MustAliasCount << " must alias responses ";
 353     PrintPercent(MustAliasCount, AliasSum);
 354     errs() << "  Alias Analysis Evaluator Pointer Alias Summary: "
 355            << NoAliasCount * 100 / AliasSum << "%/"
 356            << MayAliasCount * 100 / AliasSum << "%/"
 357            << PartialAliasCount * 100 / AliasSum << "%/"
 358            << MustAliasCount * 100 / AliasSum << "%\n";
 359   }
 360
 361   // Display the summary for mod/ref analysis
 362   int64_t ModRefSum = NoModRefCount + RefCount + ModCount + ModRefCount +
 363                       MustCount + MustRefCount + MustModCount + MustModRefCount;
 364   if (ModRefSum == 0) {
 365     errs() << "  Alias Analysis Mod/Ref Evaluator Summary: no "
 366               "mod/ref!\n";
 367   } else {
 368     errs() << "  " << ModRefSum << " Total ModRef Queries Performed\n";
 369     errs() << "  " << NoModRefCount << " no mod/ref responses ";
 370     PrintPercent(NoModRefCount, ModRefSum);
 371     errs() << "  " << ModCount << " mod responses ";
 372     PrintPercent(ModCount, ModRefSum);
 373     errs() << "  " << RefCount << " ref responses ";
 374     PrintPercent(RefCount, ModRefSum);
 375     errs() << "  " << ModRefCount << " mod & ref responses ";
 376     PrintPercent(ModRefCount, ModRefSum);
 377     errs() << "  " << MustCount << " must responses ";
 378     PrintPercent(MustCount, ModRefSum);
 379     errs() << "  " << MustModCount << " must mod responses ";
 380     PrintPercent(MustModCount, ModRefSum);
 381     errs() << "  " << MustRefCount << " must ref responses ";
 382     PrintPercent(MustRefCount, ModRefSum);
 383     errs() << "  " << MustModRefCount << " must mod & ref responses ";
 384     PrintPercent(MustModRefCount, ModRefSum);
 385     errs() << "  Alias Analysis Evaluator Mod/Ref Summary: "
 386            << NoModRefCount * 100 / ModRefSum << "%/"
 387            << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
 388            << "%/" << ModRefCount * 100 / ModRefSum << "%/"
 389            << MustCount * 100 / ModRefSum << "%/"
 390            << MustRefCount * 100 / ModRefSum << "%/"
 391            << MustModCount * 100 / ModRefSum << "%/"
 392            << MustModRefCount * 100 / ModRefSum << "%\n";
 393   }
 394 }
 395
 396 namespace llvm {
 397 class AAEvalLegacyPass : public FunctionPass {
 398   std::unique_ptr<AAEvaluator> P;
 399
 400 public:
 401   static char ID; // Pass identification, replacement for typeid
 402   AAEvalLegacyPass() : FunctionPass(ID) {
 403     initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
 404   }
 405
 406   void getAnalysisUsage(AnalysisUsage &AU) const override {
 407     AU.addRequired<AAResultsWrapperPass>();
 408     AU.setPreservesAll();
 409   }
 410
 411   bool doInitialization(Module &M) override {
 412     P.reset(new AAEvaluator());
 413     return false;
 414   }
 415
 416   bool runOnFunction(Function &F) override {
 417     P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
 418     return false;
 419   }
 420   bool doFinalization(Module &M) override {
 421     P.reset();
 422     return false;
 423   }
 424 };
 425 }
 426
 427 char AAEvalLegacyPass::ID = 0;
 428 INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
 429                       "Exhaustive Alias Analysis Precision Evaluator", false,
 430                       true)
 431 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
 432 INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
 433                     "Exhaustive Alias Analysis Precision Evaluator", false,
 434                     true)
 435
 436 FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }