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      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/Analysis/AliasAnalysis.h"
     17 #include "llvm/Assembly/Writer.h"
     18 #include "llvm/Pass.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"
     23 using namespace llvm;
     24 
     25 static cl::opt<bool>
     26 PrintAll("count-aa-print-all-queries", cl::ReallyHidden, cl::init(true));
     27 static cl::opt<bool>
     28 PrintAllFailures("count-aa-print-all-failed-queries", cl::ReallyHidden);
     29 
     30 namespace {
     31   class AliasAnalysisCounter : public ModulePass, public AliasAnalysis {
     32     unsigned No, May, Partial, 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       initializeAliasAnalysisCounterPass(*PassRegistry::getPassRegistry());
     39       No = May = Partial = Must = 0;
     40       NoMR = JustRef = JustMod = MR = 0;
     41     }
     42 
     43     void printLine(const char *Desc, unsigned Val, unsigned Sum) {
     44       errs() <<  "  " << Val << " " << Desc << " responses ("
     45              << Val*100/Sum << "%)\n";
     46     }
     47     ~AliasAnalysisCounter() {
     48       unsigned AASum = No+May+Partial+Must;
     49       unsigned MRSum = NoMR+JustRef+JustMod+MR;
     50       if (AASum + MRSum) { // Print a report if any counted queries occurred...
     51         errs() << "\n===== Alias Analysis Counter Report =====\n"
     52                << "  Analysis counted:\n"
     53                << "  " << AASum << " Total Alias Queries Performed\n";
     54         if (AASum) {
     55           printLine("no alias",     No, AASum);
     56           printLine("may alias",   May, AASum);
     57           printLine("partial alias", Partial, AASum);
     58           printLine("must alias", Must, AASum);
     59           errs() << "  Alias Analysis Counter Summary: " << No*100/AASum << "%/"
     60                  << May*100/AASum << "%/"
     61                  << Partial*100/AASum << "%/"
     62                  << Must*100/AASum<<"%\n\n";
     63         }
     64 
     65         errs() << "  " << MRSum    << " Total Mod/Ref Queries Performed\n";
     66         if (MRSum) {
     67           printLine("no mod/ref",    NoMR, MRSum);
     68           printLine("ref",        JustRef, MRSum);
     69           printLine("mod",        JustMod, MRSum);
     70           printLine("mod/ref",         MR, MRSum);
     71           errs() << "  Mod/Ref Analysis Counter Summary: " <<NoMR*100/MRSum
     72                  << "%/" << JustRef*100/MRSum << "%/" << JustMod*100/MRSum
     73                  << "%/" << MR*100/MRSum <<"%\n\n";
     74         }
     75       }
     76     }
     77 
     78     bool runOnModule(Module &M) {
     79       this->M = &M;
     80       InitializeAliasAnalysis(this);
     81       return false;
     82     }
     83 
     84     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
     85       AliasAnalysis::getAnalysisUsage(AU);
     86       AU.addRequired<AliasAnalysis>();
     87       AU.setPreservesAll();
     88     }
     89 
     90     /// getAdjustedAnalysisPointer - This method is used when a pass implements
     91     /// an analysis interface through multiple inheritance.  If needed, it
     92     /// should override this to adjust the this pointer as needed for the
     93     /// specified pass info.
     94     virtual void *getAdjustedAnalysisPointer(AnalysisID PI) {
     95       if (PI == &AliasAnalysis::ID)
     96         return (AliasAnalysis*)this;
     97       return this;
     98     }
     99 
    100     // FIXME: We could count these too...
    101     bool pointsToConstantMemory(const Location &Loc, bool OrLocal) {
    102       return getAnalysis<AliasAnalysis>().pointsToConstantMemory(Loc, OrLocal);
    103     }
    104 
    105     // Forwarding functions: just delegate to a real AA implementation, counting
    106     // the number of responses...
    107     AliasResult alias(const Location &LocA, const Location &LocB);
    108 
    109     ModRefResult getModRefInfo(ImmutableCallSite CS,
    110                                const Location &Loc);
    111     ModRefResult getModRefInfo(ImmutableCallSite CS1,
    112                                ImmutableCallSite CS2) {
    113       return AliasAnalysis::getModRefInfo(CS1,CS2);
    114     }
    115   };
    116 }
    117 
    118 char AliasAnalysisCounter::ID = 0;
    119 INITIALIZE_AG_PASS(AliasAnalysisCounter, AliasAnalysis, "count-aa",
    120                    "Count Alias Analysis Query Responses", false, true, false)
    121 
    122 ModulePass *llvm::createAliasAnalysisCounterPass() {
    123   return new AliasAnalysisCounter();
    124 }
    125 
    126 AliasAnalysis::AliasResult
    127 AliasAnalysisCounter::alias(const Location &LocA, const Location &LocB) {
    128   AliasResult R = getAnalysis<AliasAnalysis>().alias(LocA, LocB);
    129 
    130   const char *AliasString = 0;
    131   switch (R) {
    132   case NoAlias:   No++;   AliasString = "No alias"; break;
    133   case MayAlias:  May++;  AliasString = "May alias"; break;
    134   case PartialAlias: Partial++; AliasString = "Partial alias"; break;
    135   case MustAlias: Must++; AliasString = "Must alias"; break;
    136   }
    137 
    138   if (PrintAll || (PrintAllFailures && R == MayAlias)) {
    139     errs() << AliasString << ":\t";
    140     errs() << "[" << LocA.Size << "B] ";
    141     WriteAsOperand(errs(), LocA.Ptr, true, M);
    142     errs() << ", ";
    143     errs() << "[" << LocB.Size << "B] ";
    144     WriteAsOperand(errs(), LocB.Ptr, true, M);
    145     errs() << "\n";
    146   }
    147 
    148   return R;
    149 }
    150 
    151 AliasAnalysis::ModRefResult
    152 AliasAnalysisCounter::getModRefInfo(ImmutableCallSite CS,
    153                                     const Location &Loc) {
    154   ModRefResult R = getAnalysis<AliasAnalysis>().getModRefInfo(CS, Loc);
    155 
    156   const char *MRString = 0;
    157   switch (R) {
    158   case NoModRef: NoMR++;     MRString = "NoModRef"; break;
    159   case Ref:      JustRef++;  MRString = "JustRef"; break;
    160   case Mod:      JustMod++;  MRString = "JustMod"; break;
    161   case ModRef:   MR++;       MRString = "ModRef"; break;
    162   }
    163 
    164   if (PrintAll || (PrintAllFailures && R == ModRef)) {
    165     errs() << MRString << ":  Ptr: ";
    166     errs() << "[" << Loc.Size << "B] ";
    167     WriteAsOperand(errs(), Loc.Ptr, true, M);
    168     errs() << "\t<->" << *CS.getInstruction() << '\n';
    169   }
    170   return R;
    171 }
    172