lib/Analysis/AliasAnalysisCounter.cpp

//===- AliasAnalysisCounter.cpp - Alias Analysis Query Counter ------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a pass which can be used to count how many alias queries
// are being made and how the alias analysis implementation being used responds.
//
//===----------------------------------------------------------------------===//

#include "llvm/Analysis/AliasAnalysisCounter.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;

static cl::opt<bool> PrintAll("count-aa-print-all-queries", cl::ReallyHidden,
                              cl::init(true));
static cl::opt<bool> PrintAllFailures("count-aa-print-all-failed-queries",
                                      cl::ReallyHidden);

char AliasAnalysisCounter::ID = 0;
INITIALIZE_AG_PASS(AliasAnalysisCounter, AliasAnalysis, "count-aa",
                   "Count Alias Analysis Query Responses", false, true, false)

ModulePass *llvm::createAliasAnalysisCounterPass() {
  return new AliasAnalysisCounter();
}

AliasAnalysisCounter::AliasAnalysisCounter() : ModulePass(ID) {
  initializeAliasAnalysisCounterPass(*PassRegistry::getPassRegistry());
  No = May = Partial = Must = 0;
  NoMR = JustRef = JustMod = MR = 0;
}

static void printLine(const char *Desc, unsigned Val, unsigned Sum) {
  errs() << "  " << Val << " " << Desc << " responses (" << Val * 100 / Sum
         << "%)\n";
}

AliasAnalysisCounter::~AliasAnalysisCounter() {
  unsigned AASum = No + May + Partial + Must;
  unsigned MRSum = NoMR + JustRef + JustMod + MR;
  if (AASum + MRSum) { // Print a report if any counted queries occurred...
    errs() << "\n===== Alias Analysis Counter Report =====\n"
           << "  Analysis counted:\n"
           << "  " << AASum << " Total Alias Queries Performed\n";
    if (AASum) {
      printLine("no alias", No, AASum);
      printLine("may alias", May, AASum);
      printLine("partial alias", Partial, AASum);
      printLine("must alias", Must, AASum);
      errs() << "  Alias Analysis Counter Summary: " << No * 100 / AASum << "%/"
             << May * 100 / AASum << "%/" << Partial * 100 / AASum << "%/"
             << Must * 100 / AASum << "%\n\n";
    }

    errs() << "  " << MRSum << " Total MRI_Mod/MRI_Ref Queries Performed\n";
    if (MRSum) {
      printLine("no mod/ref", NoMR, MRSum);
      printLine("ref", JustRef, MRSum);
      printLine("mod", JustMod, MRSum);
      printLine("mod/ref", MR, MRSum);
      errs() << "  MRI_Mod/MRI_Ref Analysis Counter Summary: "
             << NoMR * 100 / MRSum << "%/" << JustRef * 100 / MRSum << "%/"
             << JustMod * 100 / MRSum << "%/" << MR * 100 / MRSum << "%\n\n";
    }
  }
}

bool AliasAnalysisCounter::runOnModule(Module &M) {
  this->M = &M;
  InitializeAliasAnalysis(this, &M.getDataLayout());
  return false;
}

void AliasAnalysisCounter::getAnalysisUsage(AnalysisUsage &AU) const {
  AliasAnalysis::getAnalysisUsage(AU);
  AU.addRequired<AliasAnalysis>();
  AU.setPreservesAll();
}

void *AliasAnalysisCounter::getAdjustedAnalysisPointer(AnalysisID PI) {
  if (PI == &AliasAnalysis::ID)
    return (AliasAnalysis *)this;
  return this;
}

AliasResult AliasAnalysisCounter::alias(const MemoryLocation &LocA,
                                        const MemoryLocation &LocB) {
  AliasResult R = getAnalysis<AliasAnalysis>().alias(LocA, LocB);

  const char *AliasString = nullptr;
  switch (R) {
  case NoAlias:
    No++;
    AliasString = "No alias";
    break;
  case MayAlias:
    May++;
    AliasString = "May alias";
    break;
  case PartialAlias:
    Partial++;
    AliasString = "Partial alias";
    break;
  case MustAlias:
    Must++;
    AliasString = "Must alias";
    break;
  }

  if (PrintAll || (PrintAllFailures && R == MayAlias)) {
    errs() << AliasString << ":\t";
    errs() << "[" << LocA.Size << "B] ";
    LocA.Ptr->printAsOperand(errs(), true, M);
    errs() << ", ";
    errs() << "[" << LocB.Size << "B] ";
    LocB.Ptr->printAsOperand(errs(), true, M);
    errs() << "\n";
  }

  return R;
}

ModRefInfo AliasAnalysisCounter::getModRefInfo(ImmutableCallSite CS,
                                               const MemoryLocation &Loc) {
  ModRefInfo R = getAnalysis<AliasAnalysis>().getModRefInfo(CS, Loc);

  const char *MRString = nullptr;
  switch (R) {
  case MRI_NoModRef:
    NoMR++;
    MRString = "MRI_NoModRef";
    break;
  case MRI_Ref:
    JustRef++;
    MRString = "JustRef";
    break;
  case MRI_Mod:
    JustMod++;
    MRString = "JustMod";
    break;
  case MRI_ModRef:
    MR++;
    MRString = "MRI_ModRef";
    break;
  }

  if (PrintAll || (PrintAllFailures && R == MRI_ModRef)) {
    errs() << MRString << ":  Ptr: ";
    errs() << "[" << Loc.Size << "B] ";
    Loc.Ptr->printAsOperand(errs(), true, M);
    errs() << "\t<->" << *CS.getInstruction() << '\n';
  }
  return R;
}