summaryrefslogtreecommitdiff
path: root/lib/Analysis/AliasAnalysisEvaluator.cpp
blob: 1b3daba0ab4187435340d92b357dbedaf0b071f2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
//===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
// 
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and 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/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Support/CommandLine.h"
#include <iostream>
#include <set>

using namespace llvm;

namespace {
  cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);

  cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
  cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
  cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);

  cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
  cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
  cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
  cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);

  class AAEval : public FunctionPass {
    unsigned NoAlias, MayAlias, MustAlias;
    unsigned NoModRef, Mod, Ref, ModRef;

  public:
    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
      AU.addRequired<AliasAnalysis>();
      AU.setPreservesAll();
    }
    
    bool doInitialization(Module &M) { 
      NoAlias = MayAlias = MustAlias = 0; 
      NoModRef = Mod = Ref = ModRef = 0;

      if (PrintAll) {
        PrintNoAlias = PrintMayAlias = PrintMustAlias = true;
        PrintNoModRef = PrintMod = PrintRef = PrintModRef = true;
      }
      return false; 
    }

    bool runOnFunction(Function &F);
    bool doFinalization(Module &M);
  };

  RegisterOpt<AAEval>
  X("aa-eval", "Exhaustive Alias Analysis Precision Evaluator");
}

FunctionPass *llvm::createAAEvalPass() { return new AAEval(); }

static inline void PrintResults(const char *Msg, bool P, Value *V1, Value *V2,
                                Module *M) {
  if (P) {
    std::cerr << "  " << Msg << ":\t";
    WriteAsOperand(std::cerr, V1, true, true, M) << ", ";
    WriteAsOperand(std::cerr, V2, true, true, M) << "\n";
  }
}

static inline void 
PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
                   Module *M) {
  if (P) {
    std::cerr << "  " << Msg << ":  Ptr: ";
    WriteAsOperand(std::cerr, Ptr, true, true, M);
    std::cerr << "\t<->" << *I;
  }
}

bool AAEval::runOnFunction(Function &F) {
  AliasAnalysis &AA = getAnalysis<AliasAnalysis>();

  const TargetData &TD = AA.getTargetData();
  
  std::set<Value *> Pointers;
  std::set<CallSite> CallSites;

  for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
    if (isa<PointerType>(I->getType()))    // Add all pointer arguments
      Pointers.insert(I);

  for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
    if (isa<PointerType>(I->getType())) // Add all pointer instructions
      Pointers.insert(&*I);
    Instruction &Inst = *I;
    User::op_iterator OI = Inst.op_begin();
    if ((isa<InvokeInst>(Inst) || isa<CallInst>(Inst)) &&
        isa<Function>(Inst.getOperand(0)))
      ++OI;  // Skip actual functions for direct function calls.
    for (; OI != Inst.op_end(); ++OI)
      if (isa<PointerType>((*OI)->getType()))
        Pointers.insert(*OI);

    CallSite CS = CallSite::get(&*I);
    if (CS.getInstruction()) CallSites.insert(CS);
  }

  if (PrintNoAlias || PrintMayAlias || PrintMustAlias ||
      PrintNoModRef || PrintMod || PrintRef || PrintModRef)
    std::cerr << "Function: " << F.getName() << ": " << Pointers.size()
              << " pointers, " << CallSites.size() << " call sites\n";

  // iterate over the worklist, and run the full (n^2)/2 disambiguations
  for (std::set<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
       I1 != E; ++I1) {
    unsigned I1Size = 0;
    const Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
    if (I1ElTy->isSized()) I1Size = TD.getTypeSize(I1ElTy);

    for (std::set<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
      unsigned I2Size = 0;
      const Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
      if (I2ElTy->isSized()) I2Size = TD.getTypeSize(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::MustAlias:
        PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
        ++MustAlias; break;
      default:
        std::cerr << "Unknown alias query result!\n";
      }
    }
  }

  // Mod/ref alias analysis: compare all pairs of calls and values
  for (std::set<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
       V != Ve; ++V) {
    unsigned Size = 0;
    const Type *ElTy = cast<PointerType>((*V)->getType())->getElementType();
    if (ElTy->isSized()) Size = TD.getTypeSize(ElTy);

    for (std::set<CallSite>::iterator C = CallSites.begin(), 
           Ce = CallSites.end(); C != Ce; ++C) {
      Instruction *I = C->getInstruction();
      switch (AA.getModRefInfo(*C, *V, Size)) {
      case AliasAnalysis::NoModRef:
        PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
        ++NoModRef; break;
      case AliasAnalysis::Mod:
        PrintModRefResults("     Mod", PrintMod, I, *V, F.getParent());
        ++Mod; break;
      case AliasAnalysis::Ref:
        PrintModRefResults("     Ref", PrintRef, I, *V, F.getParent());
        ++Ref; break;
      case AliasAnalysis::ModRef:
        PrintModRefResults("  ModRef", PrintModRef, I, *V, F.getParent());
        ++ModRef; break;
      default:
        std::cerr << "Unknown alias query result!\n";
      }
    }
  }

  return false;
}

bool AAEval::doFinalization(Module &M) {
  unsigned AliasSum = NoAlias + MayAlias + MustAlias;
  std::cerr << "===== Alias Analysis Evaluator Report =====\n";
  if (AliasSum == 0) {
    std::cerr << "  Alias Analysis Evaluator Summary: No pointers!\n";
  } else { 
    std::cerr << "  " << AliasSum << " Total Alias Queries Performed\n";
    std::cerr << "  " << NoAlias << " no alias responses (" 
              << NoAlias*100/AliasSum << "%)\n";
    std::cerr << "  " << MayAlias << " may alias responses (" 
              << MayAlias*100/AliasSum << "%)\n";
    std::cerr << "  " << MustAlias << " must alias responses (" 
              << MustAlias*100/AliasSum <<"%)\n";
    std::cerr << "  Alias Analysis Evaluator Pointer Alias Summary: " 
              << NoAlias*100/AliasSum  << "%/" << MayAlias*100/AliasSum << "%/" 
              << MustAlias*100/AliasSum << "%\n";
  }

  // Display the summary for mod/ref analysis
  unsigned ModRefSum = NoModRef + Mod + Ref + ModRef;
  if (ModRefSum == 0) {
    std::cerr << "  Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n";
  } else {
    std::cerr << "  " << ModRefSum << " Total ModRef Queries Performed\n";
    std::cerr << "  " << NoModRef << " no mod/ref responses (" 
              << NoModRef*100/ModRefSum << "%)\n";
    std::cerr << "  " << Mod << " mod responses (" 
              << Mod*100/ModRefSum << "%)\n";
    std::cerr << "  " << Ref << " ref responses (" 
              << Ref*100/ModRefSum <<"%)\n";
    std::cerr << "  " << ModRef << " mod & ref responses (" 
              << ModRef*100/ModRefSum <<"%)\n";
    std::cerr << "  Alias Analysis Evaluator Mod/Ref Summary: " 
              << NoModRef*100/ModRefSum  << "%/" << Mod*100/ModRefSum << "%/" 
              << Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n";
  }

  return false;
}