void CSDataRando::findArgNodes(Module &M) {
  // Create function equivalence classes from the global equivalence classes.
  EquivalenceClasses<const GlobalValue*> &GlobalECs = DSA->getGlobalECs();
  EquivalenceClasses<const Function*> FunctionECs;

  for (auto ei = GlobalECs.begin(), ee = GlobalECs.end(); ei != ee; ei++) {
    // Ignore non-leader values.
    if (!ei->isLeader()) { continue; }

    const Function *Leader = nullptr;
    for (auto mi = GlobalECs.member_begin(ei), me = GlobalECs.member_end();
         mi != me;
         mi++) {
      // Only look at functions.
      if (const Function *F = dyn_cast<Function>(*mi)) {
        if (Leader) {
          FunctionECs.unionSets(Leader, F);
        } else {
          Leader = FunctionECs.getOrInsertLeaderValue(F);
        }
      }
    }
  }

  // Make sure all Functions are part of an equivalence class. This is important
  // since non-address taken functions may not appear in GlobalECs.
  for (Function &F : M) {
    if (!F.isDeclaration()) {
      FunctionECs.insert(&F);
    }
  }

  // Go through all equivalence classes and determine the additional
  // arguments.
  for (auto ei = FunctionECs.begin(), ee = FunctionECs.end();ei != ee; ei++) {
    if (ei->isLeader()) {
      NumFunctionECs++;
      std::vector<const Function*> Functions;
      Functions.insert(Functions.end(), FunctionECs.member_begin(ei), FunctionECs.member_end());

      // If we can't safely replace uses of the function's address with its
      // clone's address then we can't safely transform indirect calls to this
      // equivalence class. We still find the arg nodes for each function to
      // replace direct calls to these functions.
      if (!DSA->canReplaceAddress(ei->getData())) {
        NumFunECsWithExternal++;
        for (const Function *F : Functions) {
          if (!F->isDeclaration()) {
            findFunctionArgNodes(F);
            FunctionInfo[F].CanReplaceAddress = false;
          }
        }
      } else {
        findFunctionArgNodes(Functions);
      }
    }
  }
}
Пример #2
0
MapVector<Instruction *, uint64_t>
llvm::computeMinimumValueSizes(ArrayRef<BasicBlock *> Blocks, DemandedBits &DB,
                               const TargetTransformInfo *TTI) {

  // DemandedBits will give us every value's live-out bits. But we want
  // to ensure no extra casts would need to be inserted, so every DAG
  // of connected values must have the same minimum bitwidth.
  EquivalenceClasses<Value *> ECs;
  SmallVector<Value *, 16> Worklist;
  SmallPtrSet<Value *, 4> Roots;
  SmallPtrSet<Value *, 16> Visited;
  DenseMap<Value *, uint64_t> DBits;
  SmallPtrSet<Instruction *, 4> InstructionSet;
  MapVector<Instruction *, uint64_t> MinBWs;

  // Determine the roots. We work bottom-up, from truncs or icmps.
  bool SeenExtFromIllegalType = false;
  for (auto *BB : Blocks)
    for (auto &I : *BB) {
      InstructionSet.insert(&I);

      if (TTI && (isa<ZExtInst>(&I) || isa<SExtInst>(&I)) &&
          !TTI->isTypeLegal(I.getOperand(0)->getType()))
        SeenExtFromIllegalType = true;

      // Only deal with non-vector integers up to 64-bits wide.
      if ((isa<TruncInst>(&I) || isa<ICmpInst>(&I)) &&
          !I.getType()->isVectorTy() &&
          I.getOperand(0)->getType()->getScalarSizeInBits() <= 64) {
        // Don't make work for ourselves. If we know the loaded type is legal,
        // don't add it to the worklist.
        if (TTI && isa<TruncInst>(&I) && TTI->isTypeLegal(I.getType()))
          continue;

        Worklist.push_back(&I);
        Roots.insert(&I);
      }
    }
  // Early exit.
  if (Worklist.empty() || (TTI && !SeenExtFromIllegalType))
    return MinBWs;

  // Now proceed breadth-first, unioning values together.
  while (!Worklist.empty()) {
    Value *Val = Worklist.pop_back_val();
    Value *Leader = ECs.getOrInsertLeaderValue(Val);

    if (Visited.count(Val))
      continue;
    Visited.insert(Val);

    // Non-instructions terminate a chain successfully.
    if (!isa<Instruction>(Val))
      continue;
    Instruction *I = cast<Instruction>(Val);

    // If we encounter a type that is larger than 64 bits, we can't represent
    // it so bail out.
    if (DB.getDemandedBits(I).getBitWidth() > 64)
      return MapVector<Instruction *, uint64_t>();

    uint64_t V = DB.getDemandedBits(I).getZExtValue();
    DBits[Leader] |= V;
    DBits[I] = V;

    // Casts, loads and instructions outside of our range terminate a chain
    // successfully.
    if (isa<SExtInst>(I) || isa<ZExtInst>(I) || isa<LoadInst>(I) ||
        !InstructionSet.count(I))
      continue;

    // Unsafe casts terminate a chain unsuccessfully. We can't do anything
    // useful with bitcasts, ptrtoints or inttoptrs and it'd be unsafe to
    // transform anything that relies on them.
    if (isa<BitCastInst>(I) || isa<PtrToIntInst>(I) || isa<IntToPtrInst>(I) ||
        !I->getType()->isIntegerTy()) {
      DBits[Leader] |= ~0ULL;
      continue;
    }

    // We don't modify the types of PHIs. Reductions will already have been
    // truncated if possible, and inductions' sizes will have been chosen by
    // indvars.
    if (isa<PHINode>(I))
      continue;

    if (DBits[Leader] == ~0ULL)
      // All bits demanded, no point continuing.
      continue;

    for (Value *O : cast<User>(I)->operands()) {
      ECs.unionSets(Leader, O);
      Worklist.push_back(O);
    }
  }

  // Now we've discovered all values, walk them to see if there are
  // any users we didn't see. If there are, we can't optimize that
  // chain.
  for (auto &I : DBits)
    for (auto *U : I.first->users())
      if (U->getType()->isIntegerTy() && DBits.count(U) == 0)
        DBits[ECs.getOrInsertLeaderValue(I.first)] |= ~0ULL;

  for (auto I = ECs.begin(), E = ECs.end(); I != E; ++I) {
    uint64_t LeaderDemandedBits = 0;
    for (auto MI = ECs.member_begin(I), ME = ECs.member_end(); MI != ME; ++MI)
      LeaderDemandedBits |= DBits[*MI];

    uint64_t MinBW = (sizeof(LeaderDemandedBits) * 8) -
                     llvm::countLeadingZeros(LeaderDemandedBits);
    // Round up to a power of 2
    if (!isPowerOf2_64((uint64_t)MinBW))
      MinBW = NextPowerOf2(MinBW);

    // We don't modify the types of PHIs. Reductions will already have been
    // truncated if possible, and inductions' sizes will have been chosen by
    // indvars.
    // If we are required to shrink a PHI, abandon this entire equivalence class.
    bool Abort = false;
    for (auto MI = ECs.member_begin(I), ME = ECs.member_end(); MI != ME; ++MI)
      if (isa<PHINode>(*MI) && MinBW < (*MI)->getType()->getScalarSizeInBits()) {
        Abort = true;
        break;
      }
    if (Abort)
      continue;

    for (auto MI = ECs.member_begin(I), ME = ECs.member_end(); MI != ME; ++MI) {
      if (!isa<Instruction>(*MI))
        continue;
      Type *Ty = (*MI)->getType();
      if (Roots.count(*MI))
        Ty = cast<Instruction>(*MI)->getOperand(0)->getType();
      if (MinBW < Ty->getScalarSizeInBits())
        MinBWs[cast<Instruction>(*MI)] = MinBW;
    }
  }

  return MinBWs;
}