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      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 #include "llvm/Analysis/AliasAnalysisEvaluator.h"
     11 #include "llvm/ADT/SetVector.h"
     12 #include "llvm/Analysis/AliasAnalysis.h"
     13 #include "llvm/IR/Constants.h"
     14 #include "llvm/IR/DataLayout.h"
     15 #include "llvm/IR/DerivedTypes.h"
     16 #include "llvm/IR/Function.h"
     17 #include "llvm/IR/Module.h"
     18 #include "llvm/IR/InstIterator.h"
     19 #include "llvm/IR/Instructions.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> PrintMod("print-mod", cl::ReallyHidden);
     35 static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
     36 static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
     37 
     38 static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden);
     39 
     40 static void PrintResults(const char *Msg, bool P, const Value *V1,
     41                          const Value *V2, const Module *M) {
     42   if (PrintAll || P) {
     43     std::string o1, o2;
     44     {
     45       raw_string_ostream os1(o1), os2(o2);
     46       V1->printAsOperand(os1, true, M);
     47       V2->printAsOperand(os2, true, M);
     48     }
     49 
     50     if (o2 < o1)
     51       std::swap(o1, o2);
     52     errs() << "  " << Msg << ":\t"
     53            << o1 << ", "
     54            << o2 << "\n";
     55   }
     56 }
     57 
     58 static inline void
     59 PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
     60                    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
     69 PrintModRefResults(const char *Msg, bool P, CallSite CSA, CallSite CSB,
     70                    Module *M) {
     71   if (PrintAll || P) {
     72     errs() << "  " << Msg << ": " << *CSA.getInstruction()
     73            << " <-> " << *CSB.getInstruction() << '\n';
     74   }
     75 }
     76 
     77 static inline void
     78 PrintLoadStoreResults(const char *Msg, bool P, const Value *V1,
     79                       const Value *V2, const Module *M) {
     80   if (PrintAll || P) {
     81     errs() << "  " << Msg << ": " << *V1
     82            << " <-> " << *V2 << '\n';
     83   }
     84 }
     85 
     86 static inline bool isInterestingPointer(Value *V) {
     87   return V->getType()->isPointerTy()
     88       && !isa<ConstantPointerNull>(V);
     89 }
     90 
     91 PreservedAnalyses AAEvaluator::run(Function &F, AnalysisManager<Function> &AM) {
     92   runInternal(F, AM.getResult<AAManager>(F));
     93   return PreservedAnalyses::all();
     94 }
     95 
     96 void AAEvaluator::runInternal(Function &F, AAResults &AA) {
     97   const DataLayout &DL = F.getParent()->getDataLayout();
     98 
     99   ++FunctionCount;
    100 
    101   SetVector<Value *> Pointers;
    102   SmallSetVector<CallSite, 16> CallSites;
    103   SetVector<Value *> Loads;
    104   SetVector<Value *> Stores;
    105 
    106   for (auto &I : F.args())
    107     if (I.getType()->isPointerTy())    // Add all pointer arguments.
    108       Pointers.insert(&I);
    109 
    110   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
    111     if (I->getType()->isPointerTy()) // Add all pointer instructions.
    112       Pointers.insert(&*I);
    113     if (EvalAAMD && isa<LoadInst>(&*I))
    114       Loads.insert(&*I);
    115     if (EvalAAMD && isa<StoreInst>(&*I))
    116       Stores.insert(&*I);
    117     Instruction &Inst = *I;
    118     if (auto CS = CallSite(&Inst)) {
    119       Value *Callee = CS.getCalledValue();
    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 : CS.data_ops())
    125         if (isInterestingPointer(DataOp))
    126           Pointers.insert(DataOp);
    127       CallSites.insert(CS);
    128     } else {
    129       // Consider all operands.
    130       for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
    131            OI != OE; ++OI)
    132         if (isInterestingPointer(*OI))
    133           Pointers.insert(*OI);
    134     }
    135   }
    136 
    137   if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
    138       PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
    139     errs() << "Function: " << F.getName() << ": " << Pointers.size()
    140            << " pointers, " << CallSites.size() << " call sites\n";
    141 
    142   // iterate over the worklist, and run the full (n^2)/2 disambiguations
    143   for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
    144        I1 != E; ++I1) {
    145     uint64_t I1Size = MemoryLocation::UnknownSize;
    146     Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
    147     if (I1ElTy->isSized()) I1Size = DL.getTypeStoreSize(I1ElTy);
    148 
    149     for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
    150       uint64_t I2Size = MemoryLocation::UnknownSize;
    151       Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
    152       if (I2ElTy->isSized()) I2Size = DL.getTypeStoreSize(I2ElTy);
    153 
    154       switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
    155       case NoAlias:
    156         PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
    157         ++NoAliasCount;
    158         break;
    159       case MayAlias:
    160         PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
    161         ++MayAliasCount;
    162         break;
    163       case PartialAlias:
    164         PrintResults("PartialAlias", PrintPartialAlias, *I1, *I2,
    165                      F.getParent());
    166         ++PartialAliasCount;
    167         break;
    168       case MustAlias:
    169         PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
    170         ++MustAliasCount;
    171         break;
    172       }
    173     }
    174   }
    175 
    176   if (EvalAAMD) {
    177     // iterate over all pairs of load, store
    178     for (Value *Load : Loads) {
    179       for (Value *Store : Stores) {
    180         switch (AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
    181                          MemoryLocation::get(cast<StoreInst>(Store)))) {
    182         case NoAlias:
    183           PrintLoadStoreResults("NoAlias", PrintNoAlias, Load, Store,
    184                                 F.getParent());
    185           ++NoAliasCount;
    186           break;
    187         case MayAlias:
    188           PrintLoadStoreResults("MayAlias", PrintMayAlias, Load, Store,
    189                                 F.getParent());
    190           ++MayAliasCount;
    191           break;
    192         case PartialAlias:
    193           PrintLoadStoreResults("PartialAlias", PrintPartialAlias, Load, Store,
    194                                 F.getParent());
    195           ++PartialAliasCount;
    196           break;
    197         case MustAlias:
    198           PrintLoadStoreResults("MustAlias", PrintMustAlias, Load, Store,
    199                                 F.getParent());
    200           ++MustAliasCount;
    201           break;
    202         }
    203       }
    204     }
    205 
    206     // iterate over all pairs of store, store
    207     for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
    208          I1 != E; ++I1) {
    209       for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
    210         switch (AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
    211                          MemoryLocation::get(cast<StoreInst>(*I2)))) {
    212         case NoAlias:
    213           PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
    214                                 F.getParent());
    215           ++NoAliasCount;
    216           break;
    217         case MayAlias:
    218           PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
    219                                 F.getParent());
    220           ++MayAliasCount;
    221           break;
    222         case PartialAlias:
    223           PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
    224                                 F.getParent());
    225           ++PartialAliasCount;
    226           break;
    227         case MustAlias:
    228           PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
    229                                 F.getParent());
    230           ++MustAliasCount;
    231           break;
    232         }
    233       }
    234     }
    235   }
    236 
    237   // Mod/ref alias analysis: compare all pairs of calls and values
    238   for (CallSite C : CallSites) {
    239     Instruction *I = C.getInstruction();
    240 
    241     for (auto Pointer : Pointers) {
    242       uint64_t Size = MemoryLocation::UnknownSize;
    243       Type *ElTy = cast<PointerType>(Pointer->getType())->getElementType();
    244       if (ElTy->isSized()) Size = DL.getTypeStoreSize(ElTy);
    245 
    246       switch (AA.getModRefInfo(C, Pointer, Size)) {
    247       case MRI_NoModRef:
    248         PrintModRefResults("NoModRef", PrintNoModRef, I, Pointer,
    249                            F.getParent());
    250         ++NoModRefCount;
    251         break;
    252       case MRI_Mod:
    253         PrintModRefResults("Just Mod", PrintMod, I, Pointer, F.getParent());
    254         ++ModCount;
    255         break;
    256       case MRI_Ref:
    257         PrintModRefResults("Just Ref", PrintRef, I, Pointer, F.getParent());
    258         ++RefCount;
    259         break;
    260       case MRI_ModRef:
    261         PrintModRefResults("Both ModRef", PrintModRef, I, Pointer,
    262                            F.getParent());
    263         ++ModRefCount;
    264         break;
    265       }
    266     }
    267   }
    268 
    269   // Mod/ref alias analysis: compare all pairs of calls
    270   for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) {
    271     for (auto D = CallSites.begin(); D != Ce; ++D) {
    272       if (D == C)
    273         continue;
    274       switch (AA.getModRefInfo(*C, *D)) {
    275       case MRI_NoModRef:
    276         PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent());
    277         ++NoModRefCount;
    278         break;
    279       case MRI_Mod:
    280         PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent());
    281         ++ModCount;
    282         break;
    283       case MRI_Ref:
    284         PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent());
    285         ++RefCount;
    286         break;
    287       case MRI_ModRef:
    288         PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent());
    289         ++ModRefCount;
    290         break;
    291       }
    292     }
    293   }
    294 }
    295 
    296 static void PrintPercent(int64_t Num, int64_t Sum) {
    297   errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
    298          << "%)\n";
    299 }
    300 
    301 AAEvaluator::~AAEvaluator() {
    302   if (FunctionCount == 0)
    303     return;
    304 
    305   int64_t AliasSum =
    306       NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
    307   errs() << "===== Alias Analysis Evaluator Report =====\n";
    308   if (AliasSum == 0) {
    309     errs() << "  Alias Analysis Evaluator Summary: No pointers!\n";
    310   } else {
    311     errs() << "  " << AliasSum << " Total Alias Queries Performed\n";
    312     errs() << "  " << NoAliasCount << " no alias responses ";
    313     PrintPercent(NoAliasCount, AliasSum);
    314     errs() << "  " << MayAliasCount << " may alias responses ";
    315     PrintPercent(MayAliasCount, AliasSum);
    316     errs() << "  " << PartialAliasCount << " partial alias responses ";
    317     PrintPercent(PartialAliasCount, AliasSum);
    318     errs() << "  " << MustAliasCount << " must alias responses ";
    319     PrintPercent(MustAliasCount, AliasSum);
    320     errs() << "  Alias Analysis Evaluator Pointer Alias Summary: "
    321            << NoAliasCount * 100 / AliasSum << "%/"
    322            << MayAliasCount * 100 / AliasSum << "%/"
    323            << PartialAliasCount * 100 / AliasSum << "%/"
    324            << MustAliasCount * 100 / AliasSum << "%\n";
    325   }
    326 
    327   // Display the summary for mod/ref analysis
    328   int64_t ModRefSum = NoModRefCount + ModCount + RefCount + ModRefCount;
    329   if (ModRefSum == 0) {
    330     errs() << "  Alias Analysis Mod/Ref Evaluator Summary: no "
    331               "mod/ref!\n";
    332   } else {
    333     errs() << "  " << ModRefSum << " Total ModRef Queries Performed\n";
    334     errs() << "  " << NoModRefCount << " no mod/ref responses ";
    335     PrintPercent(NoModRefCount, ModRefSum);
    336     errs() << "  " << ModCount << " mod responses ";
    337     PrintPercent(ModCount, ModRefSum);
    338     errs() << "  " << RefCount << " ref responses ";
    339     PrintPercent(RefCount, ModRefSum);
    340     errs() << "  " << ModRefCount << " mod & ref responses ";
    341     PrintPercent(ModRefCount, ModRefSum);
    342     errs() << "  Alias Analysis Evaluator Mod/Ref Summary: "
    343            << NoModRefCount * 100 / ModRefSum << "%/"
    344            << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
    345            << "%/" << ModRefCount * 100 / ModRefSum << "%\n";
    346   }
    347 }
    348 
    349 namespace llvm {
    350 class AAEvalLegacyPass : public FunctionPass {
    351   std::unique_ptr<AAEvaluator> P;
    352 
    353 public:
    354   static char ID; // Pass identification, replacement for typeid
    355   AAEvalLegacyPass() : FunctionPass(ID) {
    356     initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
    357   }
    358 
    359   void getAnalysisUsage(AnalysisUsage &AU) const override {
    360     AU.addRequired<AAResultsWrapperPass>();
    361     AU.setPreservesAll();
    362   }
    363 
    364   bool doInitialization(Module &M) override {
    365     P.reset(new AAEvaluator());
    366     return false;
    367   }
    368 
    369   bool runOnFunction(Function &F) override {
    370     P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
    371     return false;
    372   }
    373   bool doFinalization(Module &M) override {
    374     P.reset();
    375     return false;
    376   }
    377 };
    378 }
    379 
    380 char AAEvalLegacyPass::ID = 0;
    381 INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
    382                       "Exhaustive Alias Analysis Precision Evaluator", false,
    383                       true)
    384 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
    385 INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
    386                     "Exhaustive Alias Analysis Precision Evaluator", false,
    387                     true)
    388 
    389 FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }
    390