AliasAnalysisEvaluator.cpp revision 7f8897f22e88271cfa114998a4d6088e7c8e8e11
1//===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source 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/Constants.h" 21#include "llvm/DerivedTypes.h" 22#include "llvm/Function.h" 23#include "llvm/Instructions.h" 24#include "llvm/Pass.h" 25#include "llvm/Analysis/Passes.h" 26#include "llvm/Analysis/AliasAnalysis.h" 27#include "llvm/Assembly/Writer.h" 28#include "llvm/Target/TargetData.h" 29#include "llvm/Support/InstIterator.h" 30#include "llvm/Support/CommandLine.h" 31#include <iostream> 32#include <set> 33 34using namespace llvm; 35 36namespace { 37 cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden); 38 39 cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden); 40 cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden); 41 cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden); 42 43 cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden); 44 cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden); 45 cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden); 46 cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden); 47 48 class AAEval : public FunctionPass { 49 unsigned NoAlias, MayAlias, MustAlias; 50 unsigned NoModRef, Mod, Ref, ModRef; 51 52 public: 53 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 54 AU.addRequired<AliasAnalysis>(); 55 AU.setPreservesAll(); 56 } 57 58 bool doInitialization(Module &M) { 59 NoAlias = MayAlias = MustAlias = 0; 60 NoModRef = Mod = Ref = ModRef = 0; 61 62 if (PrintAll) { 63 PrintNoAlias = PrintMayAlias = PrintMustAlias = true; 64 PrintNoModRef = PrintMod = PrintRef = PrintModRef = true; 65 } 66 return false; 67 } 68 69 bool runOnFunction(Function &F); 70 bool doFinalization(Module &M); 71 }; 72 73 RegisterPass<AAEval> 74 X("aa-eval", "Exhaustive Alias Analysis Precision Evaluator"); 75} 76 77FunctionPass *llvm::createAAEvalPass() { return new AAEval(); } 78 79static inline void PrintResults(const char *Msg, bool P, Value *V1, Value *V2, 80 Module *M) { 81 if (P) { 82 std::cerr << " " << Msg << ":\t"; 83 WriteAsOperand(std::cerr, V1, true, true, M) << ", "; 84 WriteAsOperand(std::cerr, V2, true, true, M) << "\n"; 85 } 86} 87 88static inline void 89PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr, 90 Module *M) { 91 if (P) { 92 std::cerr << " " << Msg << ": Ptr: "; 93 WriteAsOperand(std::cerr, Ptr, true, true, M); 94 std::cerr << "\t<->" << *I; 95 } 96} 97 98bool AAEval::runOnFunction(Function &F) { 99 AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 100 101 const TargetData &TD = AA.getTargetData(); 102 103 std::set<Value *> Pointers; 104 std::set<CallSite> CallSites; 105 106 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) 107 if (isa<PointerType>(I->getType())) // 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 (isa<PointerType>(I->getType())) // Add all pointer instructions 112 Pointers.insert(&*I); 113 Instruction &Inst = *I; 114 User::op_iterator OI = Inst.op_begin(); 115 if ((isa<InvokeInst>(Inst) || isa<CallInst>(Inst)) && 116 isa<Function>(Inst.getOperand(0))) 117 ++OI; // Skip actual functions for direct function calls. 118 for (; OI != Inst.op_end(); ++OI) 119 if (isa<PointerType>((*OI)->getType()) && !isa<ConstantPointerNull>(*OI)) 120 Pointers.insert(*OI); 121 122 CallSite CS = CallSite::get(&*I); 123 if (CS.getInstruction()) CallSites.insert(CS); 124 } 125 126 if (PrintNoAlias || PrintMayAlias || PrintMustAlias || 127 PrintNoModRef || PrintMod || PrintRef || PrintModRef) 128 std::cerr << "Function: " << F.getName() << ": " << Pointers.size() 129 << " pointers, " << CallSites.size() << " call sites\n"; 130 131 // iterate over the worklist, and run the full (n^2)/2 disambiguations 132 for (std::set<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end(); 133 I1 != E; ++I1) { 134 unsigned I1Size = 0; 135 const Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType(); 136 if (I1ElTy->isSized()) I1Size = TD.getTypeSize(I1ElTy); 137 138 for (std::set<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) { 139 unsigned I2Size = 0; 140 const Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType(); 141 if (I2ElTy->isSized()) I2Size = TD.getTypeSize(I2ElTy); 142 143 switch (AA.alias(*I1, I1Size, *I2, I2Size)) { 144 case AliasAnalysis::NoAlias: 145 PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent()); 146 ++NoAlias; break; 147 case AliasAnalysis::MayAlias: 148 PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent()); 149 ++MayAlias; break; 150 case AliasAnalysis::MustAlias: 151 PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent()); 152 ++MustAlias; break; 153 default: 154 std::cerr << "Unknown alias query result!\n"; 155 } 156 } 157 } 158 159 // Mod/ref alias analysis: compare all pairs of calls and values 160 for (std::set<CallSite>::iterator C = CallSites.begin(), 161 Ce = CallSites.end(); C != Ce; ++C) { 162 Instruction *I = C->getInstruction(); 163 164 for (std::set<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end(); 165 V != Ve; ++V) { 166 unsigned Size = 0; 167 const Type *ElTy = cast<PointerType>((*V)->getType())->getElementType(); 168 if (ElTy->isSized()) Size = TD.getTypeSize(ElTy); 169 170 switch (AA.getModRefInfo(*C, *V, Size)) { 171 case AliasAnalysis::NoModRef: 172 PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent()); 173 ++NoModRef; break; 174 case AliasAnalysis::Mod: 175 PrintModRefResults(" Mod", PrintMod, I, *V, F.getParent()); 176 ++Mod; break; 177 case AliasAnalysis::Ref: 178 PrintModRefResults(" Ref", PrintRef, I, *V, F.getParent()); 179 ++Ref; break; 180 case AliasAnalysis::ModRef: 181 PrintModRefResults(" ModRef", PrintModRef, I, *V, F.getParent()); 182 ++ModRef; break; 183 default: 184 std::cerr << "Unknown alias query result!\n"; 185 } 186 } 187 } 188 189 return false; 190} 191 192static void PrintPercent(unsigned Num, unsigned Sum) { 193 std::cerr << "(" << Num*100ULL/Sum << "." 194 << ((Num*1000ULL/Sum) % 10) << "%)\n"; 195} 196 197bool AAEval::doFinalization(Module &M) { 198 unsigned AliasSum = NoAlias + MayAlias + MustAlias; 199 std::cerr << "===== Alias Analysis Evaluator Report =====\n"; 200 if (AliasSum == 0) { 201 std::cerr << " Alias Analysis Evaluator Summary: No pointers!\n"; 202 } else { 203 std::cerr << " " << AliasSum << " Total Alias Queries Performed\n"; 204 std::cerr << " " << NoAlias << " no alias responses "; 205 PrintPercent(NoAlias, AliasSum); 206 std::cerr << " " << MayAlias << " may alias responses "; 207 PrintPercent(MayAlias, AliasSum); 208 std::cerr << " " << MustAlias << " must alias responses "; 209 PrintPercent(MustAlias, AliasSum); 210 std::cerr << " Alias Analysis Evaluator Pointer Alias Summary: " 211 << NoAlias*100/AliasSum << "%/" << MayAlias*100/AliasSum << "%/" 212 << MustAlias*100/AliasSum << "%\n"; 213 } 214 215 // Display the summary for mod/ref analysis 216 unsigned ModRefSum = NoModRef + Mod + Ref + ModRef; 217 if (ModRefSum == 0) { 218 std::cerr << " Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n"; 219 } else { 220 std::cerr << " " << ModRefSum << " Total ModRef Queries Performed\n"; 221 std::cerr << " " << NoModRef << " no mod/ref responses "; 222 PrintPercent(NoModRef, ModRefSum); 223 std::cerr << " " << Mod << " mod responses "; 224 PrintPercent(Mod, ModRefSum); 225 std::cerr << " " << Ref << " ref responses "; 226 PrintPercent(Ref, ModRefSum); 227 std::cerr << " " << ModRef << " mod & ref responses "; 228 PrintPercent(ModRef, ModRefSum); 229 std::cerr << " Alias Analysis Evaluator Mod/Ref Summary: " 230 << NoModRef*100/ModRefSum << "%/" << Mod*100/ModRefSum << "%/" 231 << Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n"; 232 } 233 234 return false; 235} 236