AliasAnalysisCounter.cpp revision 791102fb1192ac9483274e54cbc42480c9b1af10 
1//===- AliasAnalysisCounter.cpp - Alias Analysis Query Counter ------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// 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 "llvm/Support/Compiler.h"
21#include "llvm/Support/ErrorHandling.h"
22#include "llvm/Support/raw_ostream.h"
23using namespace llvm;
24
25static cl::opt<bool>
26PrintAll("count-aa-print-all-queries", cl::ReallyHidden);
27static cl::opt<bool>
28PrintAllFailures("count-aa-print-all-failed-queries", cl::ReallyHidden);
29
30namespace {
31  class VISIBILITY_HIDDEN AliasAnalysisCounter
32      : public ModulePass, public AliasAnalysis {
33    unsigned No, May, Must;
34    unsigned NoMR, JustRef, JustMod, MR;
35    const char *Name;
36    Module *M;
37  public:
38    static char ID; // Class identification, replacement for typeinfo
39    AliasAnalysisCounter() : ModulePass(&ID) {
40      No = May = Must = 0;
41      NoMR = JustRef = JustMod = MR = 0;
42    }
43
44    void printLine(const char *Desc, unsigned Val, unsigned Sum) {
45      errs() <<  "  " << Val << " " << Desc << " responses ("
46             << Val*100/Sum << "%)\n";
47    }
48    ~AliasAnalysisCounter() {
49      unsigned AASum = No+May+Must;
50      unsigned MRSum = NoMR+JustRef+JustMod+MR;
51      if (AASum + MRSum) { // Print a report if any counted queries occurred...
52        errs() << "\n===== Alias Analysis Counter Report =====\n"
53               << "  Analysis counted: " << Name << "\n"
54               << "  " << AASum << " Total Alias Queries Performed\n";
55        if (AASum) {
56          printLine("no alias",     No, AASum);
57          printLine("may alias",   May, AASum);
58          printLine("must alias", Must, AASum);
59          errs() << "  Alias Analysis Counter Summary: " << No*100/AASum << "%/"
60                 << May*100/AASum << "%/" << Must*100/AASum<<"%\n\n";
61        }
62
63        errs() << "  " << MRSum    << " Total Mod/Ref Queries Performed\n";
64        if (MRSum) {
65          printLine("no mod/ref",    NoMR, MRSum);
66          printLine("ref",        JustRef, MRSum);
67          printLine("mod",        JustMod, MRSum);
68          printLine("mod/ref",         MR, MRSum);
69          errs() << "  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(CallSite CS) {
94      return getAnalysis<AliasAnalysis>().doesNotAccessMemory(CS);
95    }
96    bool doesNotAccessMemory(Function *F) {
97      return getAnalysis<AliasAnalysis>().doesNotAccessMemory(F);
98    }
99    bool onlyReadsMemory(CallSite CS) {
100      return getAnalysis<AliasAnalysis>().onlyReadsMemory(CS);
101    }
102    bool onlyReadsMemory(Function *F) {
103      return getAnalysis<AliasAnalysis>().onlyReadsMemory(F);
104    }
105
106
107    // Forwarding functions: just delegate to a real AA implementation, counting
108    // the number of responses...
109    AliasResult alias(const Value *V1, unsigned V1Size,
110                      const Value *V2, unsigned V2Size);
111
112    ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
113    ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
114      return AliasAnalysis::getModRefInfo(CS1,CS2);
115    }
116  };
117}
118
119char AliasAnalysisCounter::ID = 0;
120static RegisterPass<AliasAnalysisCounter>
121X("count-aa", "Count Alias Analysis Query Responses", false, true);
122static RegisterAnalysisGroup<AliasAnalysis> Y(X);
123
124ModulePass *llvm::createAliasAnalysisCounterPass() {
125  return new AliasAnalysisCounter();
126}
127
128AliasAnalysis::AliasResult
129AliasAnalysisCounter::alias(const Value *V1, unsigned V1Size,
130                            const Value *V2, unsigned V2Size) {
131  AliasResult R = getAnalysis<AliasAnalysis>().alias(V1, V1Size, V2, V2Size);
132
133  const char *AliasString;
134  switch (R) {
135  default: llvm_unreachable("Unknown alias type!");
136  case NoAlias:   No++;   AliasString = "No alias"; break;
137  case MayAlias:  May++;  AliasString = "May alias"; break;
138  case MustAlias: Must++; AliasString = "Must alias"; break;
139  }
140
141  if (PrintAll || (PrintAllFailures && R == MayAlias)) {
142    errs() << AliasString << ":\t";
143    errs() << "[" << V1Size << "B] ";
144    WriteAsOperand(errs(), V1, true, M);
145    errs() << ", ";
146    errs() << "[" << V2Size << "B] ";
147    WriteAsOperand(errs(), V2, true, M);
148    errs() << "\n";
149  }
150
151  return R;
152}
153
154AliasAnalysis::ModRefResult
155AliasAnalysisCounter::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
156  ModRefResult R = getAnalysis<AliasAnalysis>().getModRefInfo(CS, P, Size);
157
158  const char *MRString;
159  switch (R) {
160  default:       llvm_unreachable("Unknown mod/ref type!");
161  case NoModRef: NoMR++;     MRString = "NoModRef"; break;
162  case Ref:      JustRef++;  MRString = "JustRef"; break;
163  case Mod:      JustMod++;  MRString = "JustMod"; break;
164  case ModRef:   MR++;       MRString = "ModRef"; break;
165  }
166
167  if (PrintAll || (PrintAllFailures && R == ModRef)) {
168    errs() << MRString << ":  Ptr: ";
169    errs() << "[" << Size << "B] ";
170    WriteAsOperand(errs(), P, true, M);
171    errs() << "\t<->" << *CS.getInstruction();
172  }
173  return R;
174}
175