//===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements a simple N^2 alias analysis accuracy evaluator. // Basically, for each function in the program, it simply queries to see how the // alias analysis implementation answers alias queries between each pair of // pointers in the function. // // This is inspired and adapted from code by: Naveen Neelakantam, Francesco // Spadini, and Wojciech Stryjewski. // //===----------------------------------------------------------------------===// #include "llvm/Analysis/Passes.h" #include "llvm/ADT/SetVector.h" #include "llvm/Analysis/AliasAnalysis.h" #include "llvm/IR/Constants.h" #include "llvm/IR/DerivedTypes.h" #include "llvm/IR/Function.h" #include "llvm/IR/InstIterator.h" #include "llvm/IR/Instructions.h" #include "llvm/Pass.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" using namespace llvm; static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden); static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden); static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden); static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden); static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden); static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden); static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden); static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden); static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden); static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden); namespace { class AAEval : public FunctionPass { unsigned NoAlias, MayAlias, PartialAlias, MustAlias; unsigned NoModRef, Mod, Ref, ModRef; public: static char ID; // Pass identification, replacement for typeid AAEval() : FunctionPass(ID) { initializeAAEvalPass(*PassRegistry::getPassRegistry()); } void getAnalysisUsage(AnalysisUsage &AU) const override { AU.addRequired<AliasAnalysis>(); AU.setPreservesAll(); } bool doInitialization(Module &M) override { NoAlias = MayAlias = PartialAlias = MustAlias = 0; NoModRef = Mod = Ref = ModRef = 0; if (PrintAll) { PrintNoAlias = PrintMayAlias = true; PrintPartialAlias = PrintMustAlias = true; PrintNoModRef = PrintMod = PrintRef = PrintModRef = true; } return false; } bool runOnFunction(Function &F) override; bool doFinalization(Module &M) override; }; } char AAEval::ID = 0; INITIALIZE_PASS_BEGIN(AAEval, "aa-eval", "Exhaustive Alias Analysis Precision Evaluator", false, true) INITIALIZE_AG_DEPENDENCY(AliasAnalysis) INITIALIZE_PASS_END(AAEval, "aa-eval", "Exhaustive Alias Analysis Precision Evaluator", false, true) FunctionPass *llvm::createAAEvalPass() { return new AAEval(); } static void PrintResults(const char *Msg, bool P, const Value *V1, const Value *V2, const Module *M) { if (P) { std::string o1, o2; { raw_string_ostream os1(o1), os2(o2); V1->printAsOperand(os1, true, M); V2->printAsOperand(os2, true, M); } if (o2 < o1) std::swap(o1, o2); errs() << " " << Msg << ":\t" << o1 << ", " << o2 << "\n"; } } static inline void PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr, Module *M) { if (P) { errs() << " " << Msg << ": Ptr: "; Ptr->printAsOperand(errs(), true, M); errs() << "\t<->" << *I << '\n'; } } static inline void PrintModRefResults(const char *Msg, bool P, CallSite CSA, CallSite CSB, Module *M) { if (P) { errs() << " " << Msg << ": " << *CSA.getInstruction() << " <-> " << *CSB.getInstruction() << '\n'; } } static inline void PrintLoadStoreResults(const char *Msg, bool P, const Value *V1, const Value *V2, const Module *M) { if (P) { errs() << " " << Msg << ": " << *V1 << " <-> " << *V2 << '\n'; } } static inline bool isInterestingPointer(Value *V) { return V->getType()->isPointerTy() && !isa<ConstantPointerNull>(V); } bool AAEval::runOnFunction(Function &F) { AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); SetVector<Value *> Pointers; SetVector<CallSite> CallSites; SetVector<Value *> Loads; SetVector<Value *> Stores; for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) if (I->getType()->isPointerTy()) // Add all pointer arguments. Pointers.insert(I); for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) { if (I->getType()->isPointerTy()) // Add all pointer instructions. Pointers.insert(&*I); if (EvalAAMD && isa<LoadInst>(&*I)) Loads.insert(&*I); if (EvalAAMD && isa<StoreInst>(&*I)) Stores.insert(&*I); Instruction &Inst = *I; if (auto CS = CallSite(&Inst)) { Value *Callee = CS.getCalledValue(); // Skip actual functions for direct function calls. if (!isa<Function>(Callee) && isInterestingPointer(Callee)) Pointers.insert(Callee); // Consider formals. for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end(); AI != AE; ++AI) if (isInterestingPointer(*AI)) Pointers.insert(*AI); CallSites.insert(CS); } else { // Consider all operands. for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end(); OI != OE; ++OI) if (isInterestingPointer(*OI)) Pointers.insert(*OI); } } if (PrintNoAlias || PrintMayAlias || PrintPartialAlias || PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef) errs() << "Function: " << F.getName() << ": " << Pointers.size() << " pointers, " << CallSites.size() << " call sites\n"; // iterate over the worklist, and run the full (n^2)/2 disambiguations for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end(); I1 != E; ++I1) { uint64_t I1Size = AliasAnalysis::UnknownSize; Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType(); if (I1ElTy->isSized()) I1Size = AA.getTypeStoreSize(I1ElTy); for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) { uint64_t I2Size = AliasAnalysis::UnknownSize; Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType(); if (I2ElTy->isSized()) I2Size = AA.getTypeStoreSize(I2ElTy); switch (AA.alias(*I1, I1Size, *I2, I2Size)) { case AliasAnalysis::NoAlias: PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent()); ++NoAlias; break; case AliasAnalysis::MayAlias: PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent()); ++MayAlias; break; case AliasAnalysis::PartialAlias: PrintResults("PartialAlias", PrintPartialAlias, *I1, *I2, F.getParent()); ++PartialAlias; break; case AliasAnalysis::MustAlias: PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent()); ++MustAlias; break; } } } if (EvalAAMD) { // iterate over all pairs of load, store for (SetVector<Value *>::iterator I1 = Loads.begin(), E = Loads.end(); I1 != E; ++I1) { for (SetVector<Value *>::iterator I2 = Stores.begin(), E2 = Stores.end(); I2 != E2; ++I2) { switch (AA.alias(AA.getLocation(cast<LoadInst>(*I1)), AA.getLocation(cast<StoreInst>(*I2)))) { case AliasAnalysis::NoAlias: PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent()); ++NoAlias; break; case AliasAnalysis::MayAlias: PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent()); ++MayAlias; break; case AliasAnalysis::PartialAlias: PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2, F.getParent()); ++PartialAlias; break; case AliasAnalysis::MustAlias: PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent()); ++MustAlias; break; } } } // iterate over all pairs of store, store for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end(); I1 != E; ++I1) { for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) { switch (AA.alias(AA.getLocation(cast<StoreInst>(*I1)), AA.getLocation(cast<StoreInst>(*I2)))) { case AliasAnalysis::NoAlias: PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent()); ++NoAlias; break; case AliasAnalysis::MayAlias: PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent()); ++MayAlias; break; case AliasAnalysis::PartialAlias: PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2, F.getParent()); ++PartialAlias; break; case AliasAnalysis::MustAlias: PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent()); ++MustAlias; break; } } } } // Mod/ref alias analysis: compare all pairs of calls and values for (SetVector<CallSite>::iterator C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) { Instruction *I = C->getInstruction(); for (SetVector<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end(); V != Ve; ++V) { uint64_t Size = AliasAnalysis::UnknownSize; Type *ElTy = cast<PointerType>((*V)->getType())->getElementType(); if (ElTy->isSized()) Size = AA.getTypeStoreSize(ElTy); switch (AA.getModRefInfo(*C, *V, Size)) { case AliasAnalysis::NoModRef: PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent()); ++NoModRef; break; case AliasAnalysis::Mod: PrintModRefResults("Just Mod", PrintMod, I, *V, F.getParent()); ++Mod; break; case AliasAnalysis::Ref: PrintModRefResults("Just Ref", PrintRef, I, *V, F.getParent()); ++Ref; break; case AliasAnalysis::ModRef: PrintModRefResults("Both ModRef", PrintModRef, I, *V, F.getParent()); ++ModRef; break; } } } // Mod/ref alias analysis: compare all pairs of calls for (SetVector<CallSite>::iterator C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) { for (SetVector<CallSite>::iterator D = CallSites.begin(); D != Ce; ++D) { if (D == C) continue; switch (AA.getModRefInfo(*C, *D)) { case AliasAnalysis::NoModRef: PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent()); ++NoModRef; break; case AliasAnalysis::Mod: PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent()); ++Mod; break; case AliasAnalysis::Ref: PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent()); ++Ref; break; case AliasAnalysis::ModRef: PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent()); ++ModRef; break; } } } return false; } static void PrintPercent(unsigned Num, unsigned Sum) { errs() << "(" << Num*100ULL/Sum << "." << ((Num*1000ULL/Sum) % 10) << "%)\n"; } bool AAEval::doFinalization(Module &M) { unsigned AliasSum = NoAlias + MayAlias + PartialAlias + MustAlias; errs() << "===== Alias Analysis Evaluator Report =====\n"; if (AliasSum == 0) { errs() << " Alias Analysis Evaluator Summary: No pointers!\n"; } else { errs() << " " << AliasSum << " Total Alias Queries Performed\n"; errs() << " " << NoAlias << " no alias responses "; PrintPercent(NoAlias, AliasSum); errs() << " " << MayAlias << " may alias responses "; PrintPercent(MayAlias, AliasSum); errs() << " " << PartialAlias << " partial alias responses "; PrintPercent(PartialAlias, AliasSum); errs() << " " << MustAlias << " must alias responses "; PrintPercent(MustAlias, AliasSum); errs() << " Alias Analysis Evaluator Pointer Alias Summary: " << NoAlias*100/AliasSum << "%/" << MayAlias*100/AliasSum << "%/" << PartialAlias*100/AliasSum << "%/" << MustAlias*100/AliasSum << "%\n"; } // Display the summary for mod/ref analysis unsigned ModRefSum = NoModRef + Mod + Ref + ModRef; if (ModRefSum == 0) { errs() << " Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n"; } else { errs() << " " << ModRefSum << " Total ModRef Queries Performed\n"; errs() << " " << NoModRef << " no mod/ref responses "; PrintPercent(NoModRef, ModRefSum); errs() << " " << Mod << " mod responses "; PrintPercent(Mod, ModRefSum); errs() << " " << Ref << " ref responses "; PrintPercent(Ref, ModRefSum); errs() << " " << ModRef << " mod & ref responses "; PrintPercent(ModRef, ModRefSum); errs() << " Alias Analysis Evaluator Mod/Ref Summary: " << NoModRef*100/ModRefSum << "%/" << Mod*100/ModRefSum << "%/" << Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n"; } return false; }