AliasAnalysisCounter.cpp revision 7f8897f22e88271cfa114998a4d6088e7c8e8e11 
1//===- AliasAnalysisCounter.cpp - Alias Analysis Query Counter ------------===//
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 pass which can be used to count how many alias queries
11// are being made and how the alias analysis implementation being used responds.
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/Analysis/Passes.h"
16#include "llvm/Pass.h"
17#include "llvm/Analysis/AliasAnalysis.h"
18#include "llvm/Assembly/Writer.h"
19#include "llvm/Support/CommandLine.h"
20#include <iostream>
21using namespace llvm;
22
23namespace {
24  cl::opt<bool>
25  PrintAll("count-aa-print-all-queries", cl::ReallyHidden);
26  cl::opt<bool>
27  PrintAllFailures("count-aa-print-all-failed-queries", cl::ReallyHidden);
28
29  class AliasAnalysisCounter : public ModulePass, public AliasAnalysis {
30    unsigned No, May, Must;
31    unsigned NoMR, JustRef, JustMod, MR;
32    const char *Name;
33    Module *M;
34  public:
35    AliasAnalysisCounter() {
36      No = May = Must = 0;
37      NoMR = JustRef = JustMod = MR = 0;
38    }
39
40    void printLine(const char *Desc, unsigned Val, unsigned Sum) {
41      std::cerr <<  "  " << Val << " " << Desc << " responses ("
42                << Val*100/Sum << "%)\n";
43    }
44    ~AliasAnalysisCounter() {
45      unsigned AASum = No+May+Must;
46      unsigned MRSum = NoMR+JustRef+JustMod+MR;
47      if (AASum + MRSum) { // Print a report if any counted queries occurred...
48        std::cerr
49          << "\n===== Alias Analysis Counter Report =====\n"
50          << "  Analysis counted: " << Name << "\n"
51          << "  " << AASum << " Total Alias Queries Performed\n";
52        if (AASum) {
53          printLine("no alias",     No, AASum);
54          printLine("may alias",   May, AASum);
55          printLine("must alias", Must, AASum);
56          std::cerr
57            << "  Alias Analysis Counter Summary: " << No*100/AASum << "%/"
58            << May*100/AASum << "%/" << Must*100/AASum<<"%\n\n";
59        }
60
61        std::cerr
62          << "  " << MRSum    << " Total Mod/Ref Queries Performed\n";
63        if (MRSum) {
64          printLine("no mod/ref",    NoMR, MRSum);
65          printLine("ref",        JustRef, MRSum);
66          printLine("mod",        JustMod, MRSum);
67          printLine("mod/ref",         MR, MRSum);
68          std::cerr
69            << "  Mod/Ref Analysis Counter Summary: " << NoMR*100/MRSum<< "%/"
70            << JustRef*100/MRSum << "%/" << JustMod*100/MRSum << "%/"
71            << MR*100/MRSum <<"%\n\n";
72        }
73      }
74    }
75
76    bool runOnModule(Module &M) {
77      this->M = &M;
78      InitializeAliasAnalysis(this);
79      Name = dynamic_cast<Pass*>(&getAnalysis<AliasAnalysis>())->getPassName();
80      return false;
81    }
82
83    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
84      AliasAnalysis::getAnalysisUsage(AU);
85      AU.addRequired<AliasAnalysis>();
86      AU.setPreservesAll();
87    }
88
89    // FIXME: We could count these too...
90    bool pointsToConstantMemory(const Value *P) {
91      return getAnalysis<AliasAnalysis>().pointsToConstantMemory(P);
92    }
93    bool doesNotAccessMemory(Function *F) {
94      return getAnalysis<AliasAnalysis>().doesNotAccessMemory(F);
95    }
96    bool onlyReadsMemory(Function *F) {
97      return getAnalysis<AliasAnalysis>().onlyReadsMemory(F);
98    }
99
100
101    // Forwarding functions: just delegate to a real AA implementation, counting
102    // the number of responses...
103    AliasResult alias(const Value *V1, unsigned V1Size,
104                      const Value *V2, unsigned V2Size);
105
106    ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
107    ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
108      return AliasAnalysis::getModRefInfo(CS1,CS2);
109    }
110  };
111
112  RegisterPass<AliasAnalysisCounter>
113  X("count-aa", "Count Alias Analysis Query Responses");
114  RegisterAnalysisGroup<AliasAnalysis, AliasAnalysisCounter> Y;
115}
116
117ModulePass *llvm::createAliasAnalysisCounterPass() {
118  return new AliasAnalysisCounter();
119}
120
121AliasAnalysis::AliasResult
122AliasAnalysisCounter::alias(const Value *V1, unsigned V1Size,
123                            const Value *V2, unsigned V2Size) {
124  AliasResult R = getAnalysis<AliasAnalysis>().alias(V1, V1Size, V2, V2Size);
125
126  const char *AliasString;
127  switch (R) {
128  default: assert(0 && "Unknown alias type!");
129  case NoAlias:   No++;   AliasString = "No alias"; break;
130  case MayAlias:  May++;  AliasString = "May alias"; break;
131  case MustAlias: Must++; AliasString = "Must alias"; break;
132  }
133
134  if (PrintAll || (PrintAllFailures && R == MayAlias)) {
135    std::cerr << AliasString << ":\t";
136    std::cerr << "[" << V1Size << "B] ";
137    WriteAsOperand(std::cerr, V1, true, true, M) << ", ";
138    std::cerr << "[" << V2Size << "B] ";
139    WriteAsOperand(std::cerr, V2, true, true, M) << "\n";
140  }
141
142  return R;
143}
144
145AliasAnalysis::ModRefResult
146AliasAnalysisCounter::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
147  ModRefResult R = getAnalysis<AliasAnalysis>().getModRefInfo(CS, P, Size);
148
149  const char *MRString;
150  switch (R) {
151  default:       assert(0 && "Unknown mod/ref type!");
152  case NoModRef: NoMR++;     MRString = "NoModRef"; break;
153  case Ref:      JustRef++;  MRString = "JustRef"; break;
154  case Mod:      JustMod++;  MRString = "JustMod"; break;
155  case ModRef:   MR++;       MRString = "ModRef"; break;
156  }
157
158  if (PrintAll || (PrintAllFailures && R == ModRef)) {
159    std::cerr << MRString << ":  Ptr: ";
160    std::cerr << "[" << Size << "B] ";
161    WriteAsOperand(std::cerr, P, true, true, M);
162    std::cerr << "\t<->" << *CS.getInstruction();
163  }
164  return R;
165}
166