AliasAnalysisCounter.cpp revision 198892 
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/ErrorHandling.h"
21#include "llvm/Support/raw_ostream.h"
22using namespace llvm;
23
24static cl::opt<bool>
25PrintAll("count-aa-print-all-queries", cl::ReallyHidden, cl::init(true));
26static cl::opt<bool>
27PrintAllFailures("count-aa-print-all-failed-queries", cl::ReallyHidden);
28
29namespace {
30  class AliasAnalysisCounter : public ModulePass, public AliasAnalysis {
31    unsigned No, May, Must;
32    unsigned NoMR, JustRef, JustMod, MR;
33    const char *Name;
34    Module *M;
35  public:
36    static char ID; // Class identification, replacement for typeinfo
37    AliasAnalysisCounter() : ModulePass(&ID) {
38      No = May = Must = 0;
39      NoMR = JustRef = JustMod = MR = 0;
40    }
41
42    void printLine(const char *Desc, unsigned Val, unsigned Sum) {
43      errs() <<  "  " << Val << " " << Desc << " responses ("
44             << Val*100/Sum << "%)\n";
45    }
46    ~AliasAnalysisCounter() {
47      unsigned AASum = No+May+Must;
48      unsigned MRSum = NoMR+JustRef+JustMod+MR;
49      if (AASum + MRSum) { // Print a report if any counted queries occurred...
50        errs() << "\n===== Alias Analysis Counter Report =====\n"
51               << "  Analysis counted: " << Name << "\n"
52               << "  " << AASum << " Total Alias Queries Performed\n";
53        if (AASum) {
54          printLine("no alias",     No, AASum);
55          printLine("may alias",   May, AASum);
56          printLine("must alias", Must, AASum);
57          errs() << "  Alias Analysis Counter Summary: " << No*100/AASum << "%/"
58                 << May*100/AASum << "%/" << Must*100/AASum<<"%\n\n";
59        }
60
61        errs() << "  " << MRSum    << " Total Mod/Ref Queries Performed\n";
62        if (MRSum) {
63          printLine("no mod/ref",    NoMR, MRSum);
64          printLine("ref",        JustRef, MRSum);
65          printLine("mod",        JustMod, MRSum);
66          printLine("mod/ref",         MR, MRSum);
67          errs() << "  Mod/Ref Analysis Counter Summary: " <<NoMR*100/MRSum
68                 << "%/" << JustRef*100/MRSum << "%/" << JustMod*100/MRSum
69                 << "%/" << MR*100/MRSum <<"%\n\n";
70        }
71      }
72    }
73
74    bool runOnModule(Module &M) {
75      this->M = &M;
76      InitializeAliasAnalysis(this);
77      Name = dynamic_cast<Pass*>(&getAnalysis<AliasAnalysis>())->getPassName();
78      return false;
79    }
80
81    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
82      AliasAnalysis::getAnalysisUsage(AU);
83      AU.addRequired<AliasAnalysis>();
84      AU.setPreservesAll();
85    }
86
87    // FIXME: We could count these too...
88    bool pointsToConstantMemory(const Value *P) {
89      return getAnalysis<AliasAnalysis>().pointsToConstantMemory(P);
90    }
91
92    // Forwarding functions: just delegate to a real AA implementation, counting
93    // the number of responses...
94    AliasResult alias(const Value *V1, unsigned V1Size,
95                      const Value *V2, unsigned V2Size);
96
97    ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
98    ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
99      return AliasAnalysis::getModRefInfo(CS1,CS2);
100    }
101  };
102}
103
104char AliasAnalysisCounter::ID = 0;
105static RegisterPass<AliasAnalysisCounter>
106X("count-aa", "Count Alias Analysis Query Responses", false, true);
107static RegisterAnalysisGroup<AliasAnalysis> Y(X);
108
109ModulePass *llvm::createAliasAnalysisCounterPass() {
110  return new AliasAnalysisCounter();
111}
112
113AliasAnalysis::AliasResult
114AliasAnalysisCounter::alias(const Value *V1, unsigned V1Size,
115                            const Value *V2, unsigned V2Size) {
116  AliasResult R = getAnalysis<AliasAnalysis>().alias(V1, V1Size, V2, V2Size);
117
118  const char *AliasString;
119  switch (R) {
120  default: llvm_unreachable("Unknown alias type!");
121  case NoAlias:   No++;   AliasString = "No alias"; break;
122  case MayAlias:  May++;  AliasString = "May alias"; break;
123  case MustAlias: Must++; AliasString = "Must alias"; break;
124  }
125
126  if (PrintAll || (PrintAllFailures && R == MayAlias)) {
127    errs() << AliasString << ":\t";
128    errs() << "[" << V1Size << "B] ";
129    WriteAsOperand(errs(), V1, true, M);
130    errs() << ", ";
131    errs() << "[" << V2Size << "B] ";
132    WriteAsOperand(errs(), V2, true, M);
133    errs() << "\n";
134  }
135
136  return R;
137}
138
139AliasAnalysis::ModRefResult
140AliasAnalysisCounter::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
141  ModRefResult R = getAnalysis<AliasAnalysis>().getModRefInfo(CS, P, Size);
142
143  const char *MRString;
144  switch (R) {
145  default:       llvm_unreachable("Unknown mod/ref type!");
146  case NoModRef: NoMR++;     MRString = "NoModRef"; break;
147  case Ref:      JustRef++;  MRString = "JustRef"; break;
148  case Mod:      JustMod++;  MRString = "JustMod"; break;
149  case ModRef:   MR++;       MRString = "ModRef"; break;
150  }
151
152  if (PrintAll || (PrintAllFailures && R == ModRef)) {
153    errs() << MRString << ":  Ptr: ";
154    errs() << "[" << Size << "B] ";
155    WriteAsOperand(errs(), P, true, M);
156    errs() << "\t<->" << *CS.getInstruction();
157  }
158  return R;
159}
160