AliasAnalysisCounter.cpp revision c5e5b3c830db331974ddae3d8fb98e678b3a7152 
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/Debug.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, cl::init(true));
27static cl::opt<bool>
28PrintAllFailures("count-aa-print-all-failed-queries", cl::ReallyHidden);
29
30namespace {
31  class AliasAnalysisCounter : public ModulePass, public AliasAnalysis {
32    unsigned No, May, Must;
33    unsigned NoMR, JustRef, JustMod, MR;
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:\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      return false;
78    }
79
80    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
81      AliasAnalysis::getAnalysisUsage(AU);
82      AU.addRequired<AliasAnalysis>();
83      AU.setPreservesAll();
84    }
85
86    /// getAdjustedAnalysisPointer - This method is used when a pass implements
87    /// an analysis interface through multiple inheritance.  If needed, it
88    /// should override this to adjust the this pointer as needed for the
89    /// specified pass info.
90    virtual void *getAdjustedAnalysisPointer(const PassInfo *PI) {
91      if (PI->isPassID(&AliasAnalysis::ID))
92        return (AliasAnalysis*)this;
93      return this;
94    }
95
96    // FIXME: We could count these too...
97    bool pointsToConstantMemory(const Value *P) {
98      return getAnalysis<AliasAnalysis>().pointsToConstantMemory(P);
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
113char AliasAnalysisCounter::ID = 0;
114static RegisterPass<AliasAnalysisCounter>
115X("count-aa", "Count Alias Analysis Query Responses", false, true);
116static RegisterAnalysisGroup<AliasAnalysis> Y(X);
117
118ModulePass *llvm::createAliasAnalysisCounterPass() {
119  return new AliasAnalysisCounter();
120}
121
122AliasAnalysis::AliasResult
123AliasAnalysisCounter::alias(const Value *V1, unsigned V1Size,
124                            const Value *V2, unsigned V2Size) {
125  AliasResult R = getAnalysis<AliasAnalysis>().alias(V1, V1Size, V2, V2Size);
126
127  const char *AliasString;
128  switch (R) {
129  default: llvm_unreachable("Unknown alias type!");
130  case NoAlias:   No++;   AliasString = "No alias"; break;
131  case MayAlias:  May++;  AliasString = "May alias"; break;
132  case MustAlias: Must++; AliasString = "Must alias"; break;
133  }
134
135  if (PrintAll || (PrintAllFailures && R == MayAlias)) {
136    errs() << AliasString << ":\t";
137    errs() << "[" << V1Size << "B] ";
138    WriteAsOperand(errs(), V1, true, M);
139    errs() << ", ";
140    errs() << "[" << V2Size << "B] ";
141    WriteAsOperand(errs(), V2, true, M);
142    errs() << "\n";
143  }
144
145  return R;
146}
147
148AliasAnalysis::ModRefResult
149AliasAnalysisCounter::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
150  ModRefResult R = getAnalysis<AliasAnalysis>().getModRefInfo(CS, P, Size);
151
152  const char *MRString;
153  switch (R) {
154  default:       llvm_unreachable("Unknown mod/ref type!");
155  case NoModRef: NoMR++;     MRString = "NoModRef"; break;
156  case Ref:      JustRef++;  MRString = "JustRef"; break;
157  case Mod:      JustMod++;  MRString = "JustMod"; break;
158  case ModRef:   MR++;       MRString = "ModRef"; break;
159  }
160
161  if (PrintAll || (PrintAllFailures && R == ModRef)) {
162    errs() << MRString << ":  Ptr: ";
163    errs() << "[" << Size << "B] ";
164    WriteAsOperand(errs(), P, true, M);
165    errs() << "\t<->" << *CS.getInstruction();
166  }
167  return R;
168}
169