LLVM API Documentation

AliasAnalysisCounter.cpp

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00001 //===- AliasAnalysisCounter.cpp - Alias Analysis Query Counter ------------===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file implements a pass which can be used to count how many alias queries
00011 // are being made and how the alias analysis implementation being used responds.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #include "llvm/Analysis/Passes.h"
00016 #include "llvm/Pass.h"
00017 #include "llvm/Analysis/AliasAnalysis.h"
00018 #include "llvm/Assembly/Writer.h"
00019 #include "llvm/Support/CommandLine.h"
00020 #include <iostream>
00021 using namespace llvm;
00022 
00023 namespace {
00024   cl::opt<bool>
00025   PrintAll("count-aa-print-all-queries", cl::ReallyHidden);
00026   cl::opt<bool>
00027   PrintAllFailures("count-aa-print-all-failed-queries", cl::ReallyHidden);
00028 
00029   class AliasAnalysisCounter : public ModulePass, public AliasAnalysis {
00030     unsigned No, May, Must;
00031     unsigned NoMR, JustRef, JustMod, MR;
00032     const char *Name;
00033     Module *M;
00034   public:
00035     AliasAnalysisCounter() {
00036       No = May = Must = 0;
00037       NoMR = JustRef = JustMod = MR = 0;
00038     }
00039 
00040     void printLine(const char *Desc, unsigned Val, unsigned Sum) {
00041       std::cerr <<  "  " << Val << " " << Desc << " responses ("
00042                 << Val*100/Sum << "%)\n";
00043     }
00044     ~AliasAnalysisCounter() {
00045       unsigned AASum = No+May+Must;
00046       unsigned MRSum = NoMR+JustRef+JustMod+MR;
00047       if (AASum + MRSum) { // Print a report if any counted queries occurred...
00048         std::cerr
00049           << "\n===== Alias Analysis Counter Report =====\n"
00050           << "  Analysis counted: " << Name << "\n"
00051           << "  " << AASum << " Total Alias Queries Performed\n";
00052         if (AASum) {
00053           printLine("no alias",     No, AASum);
00054           printLine("may alias",   May, AASum);
00055           printLine("must alias", Must, AASum);
00056           std::cerr
00057             << "  Alias Analysis Counter Summary: " << No*100/AASum << "%/"
00058             << May*100/AASum << "%/" << Must*100/AASum<<"%\n\n";
00059         }
00060 
00061         std::cerr
00062           << "  " << MRSum    << " Total Mod/Ref Queries Performed\n";
00063         if (MRSum) {
00064           printLine("no mod/ref",    NoMR, MRSum);
00065           printLine("ref",        JustRef, MRSum);
00066           printLine("mod",        JustMod, MRSum);
00067           printLine("mod/ref",         MR, MRSum);
00068           std::cerr
00069             << "  Mod/Ref Analysis Counter Summary: " << NoMR*100/MRSum<< "%/"
00070             << JustRef*100/MRSum << "%/" << JustMod*100/MRSum << "%/"
00071             << MR*100/MRSum <<"%\n\n";
00072         }
00073       }
00074     }
00075 
00076     bool runOnModule(Module &M) {
00077       this->M = &M;
00078       InitializeAliasAnalysis(this);
00079       Name = dynamic_cast<Pass*>(&getAnalysis<AliasAnalysis>())->getPassName();
00080       return false;
00081     }
00082 
00083     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
00084       AliasAnalysis::getAnalysisUsage(AU);
00085       AU.addRequired<AliasAnalysis>();
00086       AU.setPreservesAll();
00087     }
00088 
00089     // FIXME: We could count these too...
00090     bool pointsToConstantMemory(const Value *P) {
00091       return getAnalysis<AliasAnalysis>().pointsToConstantMemory(P);
00092     }
00093     bool doesNotAccessMemory(Function *F) {
00094       return getAnalysis<AliasAnalysis>().doesNotAccessMemory(F);
00095     }
00096     bool onlyReadsMemory(Function *F) {
00097       return getAnalysis<AliasAnalysis>().onlyReadsMemory(F);
00098     }
00099 
00100 
00101     // Forwarding functions: just delegate to a real AA implementation, counting
00102     // the number of responses...
00103     AliasResult alias(const Value *V1, unsigned V1Size,
00104                       const Value *V2, unsigned V2Size);
00105 
00106     ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
00107     ModRefResult getModRefInfo(CallSite CS1, CallSite CS2) {
00108       return AliasAnalysis::getModRefInfo(CS1,CS2);
00109     }
00110   };
00111 
00112   RegisterOpt<AliasAnalysisCounter>
00113   X("count-aa", "Count Alias Analysis Query Responses");
00114   RegisterAnalysisGroup<AliasAnalysis, AliasAnalysisCounter> Y;
00115 }
00116 
00117 ModulePass *llvm::createAliasAnalysisCounterPass() {
00118   return new AliasAnalysisCounter();
00119 }
00120 
00121 AliasAnalysis::AliasResult
00122 AliasAnalysisCounter::alias(const Value *V1, unsigned V1Size,
00123                             const Value *V2, unsigned V2Size) {
00124   AliasResult R = getAnalysis<AliasAnalysis>().alias(V1, V1Size, V2, V2Size);
00125 
00126   const char *AliasString;
00127   switch (R) {
00128   default: assert(0 && "Unknown alias type!");
00129   case NoAlias:   No++;   AliasString = "No alias"; break;
00130   case MayAlias:  May++;  AliasString = "May alias"; break;
00131   case MustAlias: Must++; AliasString = "Must alias"; break;
00132   }
00133 
00134   if (PrintAll || (PrintAllFailures && R == MayAlias)) {
00135     std::cerr << AliasString << ":\t";
00136     std::cerr << "[" << V1Size << "B] ";
00137     WriteAsOperand(std::cerr, V1, true, true, M) << ", ";
00138     std::cerr << "[" << V2Size << "B] ";
00139     WriteAsOperand(std::cerr, V2, true, true, M) << "\n";
00140   }
00141 
00142   return R;
00143 }
00144 
00145 AliasAnalysis::ModRefResult
00146 AliasAnalysisCounter::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
00147   ModRefResult R = getAnalysis<AliasAnalysis>().getModRefInfo(CS, P, Size);
00148 
00149   const char *MRString;
00150   switch (R) {
00151   default:       assert(0 && "Unknown mod/ref type!");
00152   case NoModRef: NoMR++;     MRString = "NoModRef"; break;
00153   case Ref:      JustRef++;  MRString = "JustRef"; break;
00154   case Mod:      JustMod++;  MRString = "JustMod"; break;
00155   case ModRef:   MR++;       MRString = "ModRef"; break;
00156   }
00157 
00158   if (PrintAll || (PrintAllFailures && R == ModRef)) {
00159     std::cerr << MRString << ":  Ptr: ";
00160     std::cerr << "[" << Size << "B] ";
00161     WriteAsOperand(std::cerr, P, true, true, M);
00162     std::cerr << "\t<->" << *CS.getInstruction();
00163   }
00164   return R;
00165 }