AliasAnalysisEvaluator.cpp revision 9a4f8ef78757882ceb2edbf90f37439deb112c88
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/Analysis/AliasAnalysis.h" 21#include "llvm/Pass.h" 22#include "llvm/Function.h" 23#include "llvm/Type.h" 24#include "llvm/Support/InstIterator.h" 25#include "llvm/Assembly/Writer.h" 26#include "Support/CommandLine.h" 27#include <set> 28using namespace llvm; 29 30namespace { 31 cl::opt<bool> PrintNo ("print-no-aliases", cl::ReallyHidden); 32 cl::opt<bool> PrintMay ("print-may-aliases", cl::ReallyHidden); 33 cl::opt<bool> PrintMust("print-must-aliases", cl::ReallyHidden); 34 35 class AAEval : public FunctionPass { 36 unsigned No, May, Must; 37 38 public: 39 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 40 AU.addRequired<AliasAnalysis>(); 41 AU.setPreservesAll(); 42 } 43 44 bool doInitialization(Module &M) { No = May = Must = 0; return false; } 45 bool runOnFunction(Function &F); 46 bool doFinalization(Module &M); 47 }; 48 49 RegisterOpt<AAEval> 50 X("aa-eval", "Exhaustive Alias Analysis Precision Evaluator"); 51} 52 53static inline void PrintResults(const char *Msg, bool P, Value *V1, Value *V2, 54 Module *M) { 55 if (P) { 56 std::cerr << " " << Msg << ":\t"; 57 WriteAsOperand(std::cerr, V1, true, true, M) << ", "; 58 WriteAsOperand(std::cerr, V2, true, true, M) << "\n"; 59 } 60} 61 62bool AAEval::runOnFunction(Function &F) { 63 AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 64 65 std::set<Value *> Pointers; 66 67 for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I) 68 if (isa<PointerType>(I->getType())) // Add all pointer arguments 69 Pointers.insert(I); 70 71 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) { 72 if (isa<PointerType>((*I)->getType())) // Add all pointer instructions 73 Pointers.insert(*I); 74 for (User::op_iterator OI = (*I)->op_begin(); OI != (*I)->op_end(); ++OI) 75 if (isa<PointerType>((*OI)->getType())) 76 Pointers.insert(*OI); 77 } 78 79 if (PrintNo || PrintMay || PrintMust) 80 std::cerr << "Function: " << F.getName() << "\n"; 81 82 // iterate over the worklist, and run the full (n^2)/2 disambiguations 83 for (std::set<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end(); 84 I1 != E; ++I1) 85 for (std::set<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) 86 switch (AA.alias(*I1, 0, *I2, 0)) { 87 case AliasAnalysis::NoAlias: 88 PrintResults("No", PrintNo, *I1, *I2, F.getParent()); 89 ++No; break; 90 case AliasAnalysis::MayAlias: 91 PrintResults("May", PrintMay, *I1, *I2, F.getParent()); 92 ++May; break; 93 case AliasAnalysis::MustAlias: 94 PrintResults("Must", PrintMust, *I1, *I2, F.getParent()); 95 ++Must; break; 96 default: 97 std::cerr << "Unknown alias query result!\n"; 98 } 99 100 return false; 101} 102 103bool AAEval::doFinalization(Module &M) { 104 unsigned Sum = No+May+Must; 105 std::cerr << "===== Alias Analysis Evaluator Report =====\n"; 106 if (Sum == 0) { 107 std::cerr << " Alias Analysis Evaluator Summary: No pointers!\n"; 108 return false; 109 } 110 111 std::cerr << " " << Sum << " Total Alias Queries Performed\n"; 112 std::cerr << " " << No << " no alias responses (" << No*100/Sum << "%)\n"; 113 std::cerr << " " << May << " may alias responses (" << May*100/Sum << "%)\n"; 114 std::cerr << " " << Must << " must alias responses (" <<Must*100/Sum<<"%)\n"; 115 std::cerr << " Alias Analysis Evaluator Summary: " << No*100/Sum << "%/" 116 << May*100/Sum << "%/" << Must*100/Sum<<"%\n"; 117 return false; 118} 119