C++ GetElementPtrInst::getSourceElementType方法代码示例

bool Scalarizer::visitGetElementPtrInst(GetElementPtrInst &GEPI) {
  VectorType *VT = dyn_cast<VectorType>(GEPI.getType());
  if (!VT)
    return false;

  IRBuilder<> Builder(&GEPI);
  unsigned NumElems = VT->getNumElements();
  unsigned NumIndices = GEPI.getNumIndices();

  Scatterer Base = scatter(&GEPI, GEPI.getOperand(0));

  SmallVector<Scatterer, 8> Ops;
  Ops.resize(NumIndices);
  for (unsigned I = 0; I < NumIndices; ++I)
    Ops[I] = scatter(&GEPI, GEPI.getOperand(I + 1));

  ValueVector Res;
  Res.resize(NumElems);
  for (unsigned I = 0; I < NumElems; ++I) {
    SmallVector<Value *, 8> Indices;
    Indices.resize(NumIndices);
    for (unsigned J = 0; J < NumIndices; ++J)
      Indices[J] = Ops[J][I];
    Res[I] = Builder.CreateGEP(GEPI.getSourceElementType(), Base[I], Indices,
                               GEPI.getName() + ".i" + Twine(I));
    if (GEPI.isInBounds())
      if (GetElementPtrInst *NewGEPI = dyn_cast<GetElementPtrInst>(Res[I]))
        NewGEPI->setIsInBounds();
  }
  gather(&GEPI, Res);
  return true;
}

// Returns a clone of `I` with its operands converted to those specified in
// ValueWithNewAddrSpace. Due to potential cycles in the data flow graph, an
// operand whose address space needs to be modified might not exist in
// ValueWithNewAddrSpace. In that case, uses undef as a placeholder operand and
// adds that operand use to UndefUsesToFix so that caller can fix them later.
//
// Note that we do not necessarily clone `I`, e.g., if it is an addrspacecast
// from a pointer whose type already matches. Therefore, this function returns a
// Value* instead of an Instruction*.
static Value *cloneInstructionWithNewAddressSpace(
    Instruction *I, unsigned NewAddrSpace,
    const ValueToValueMapTy &ValueWithNewAddrSpace,
    SmallVectorImpl<const Use *> *UndefUsesToFix) {
  Type *NewPtrType =
      I->getType()->getPointerElementType()->getPointerTo(NewAddrSpace);

  if (I->getOpcode() == Instruction::AddrSpaceCast) {
    Value *Src = I->getOperand(0);
    // Because `I` is flat, the source address space must be specific.
    // Therefore, the inferred address space must be the source space, according
    // to our algorithm.
    assert(Src->getType()->getPointerAddressSpace() == NewAddrSpace);
    if (Src->getType() != NewPtrType)
      return new BitCastInst(Src, NewPtrType);
    return Src;
  }

  // Computes the converted pointer operands.
  SmallVector<Value *, 4> NewPointerOperands;
  for (const Use &OperandUse : I->operands()) {
    if (!OperandUse.get()->getType()->isPointerTy())
      NewPointerOperands.push_back(nullptr);
    else
      NewPointerOperands.push_back(operandWithNewAddressSpaceOrCreateUndef(
                                     OperandUse, NewAddrSpace, ValueWithNewAddrSpace, UndefUsesToFix));
  }

  switch (I->getOpcode()) {
  case Instruction::BitCast:
    return new BitCastInst(NewPointerOperands[0], NewPtrType);
  case Instruction::PHI: {
    assert(I->getType()->isPointerTy());
    PHINode *PHI = cast<PHINode>(I);
    PHINode *NewPHI = PHINode::Create(NewPtrType, PHI->getNumIncomingValues());
    for (unsigned Index = 0; Index < PHI->getNumIncomingValues(); ++Index) {
      unsigned OperandNo = PHINode::getOperandNumForIncomingValue(Index);
      NewPHI->addIncoming(NewPointerOperands[OperandNo],
                          PHI->getIncomingBlock(Index));
    }
    return NewPHI;
  }
  case Instruction::GetElementPtr: {
    GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
    GetElementPtrInst *NewGEP = GetElementPtrInst::Create(
        GEP->getSourceElementType(), NewPointerOperands[0],
        SmallVector<Value *, 4>(GEP->idx_begin(), GEP->idx_end()));
    NewGEP->setIsInBounds(GEP->isInBounds());
    return NewGEP;
  }
  case Instruction::Select: {
    assert(I->getType()->isPointerTy());
    return SelectInst::Create(I->getOperand(0), NewPointerOperands[1],
                              NewPointerOperands[2], "", nullptr, I);
  }
  default:
    llvm_unreachable("Unexpected opcode");
  }
}

bool EfficiencySanitizer::instrumentGetElementPtr(Instruction *I, Module &M) {
  GetElementPtrInst *GepInst = dyn_cast<GetElementPtrInst>(I);
  bool Res = false;
  if (GepInst == nullptr || GepInst->getNumIndices() == 1) {
    ++NumIgnoredGEPs;
    return false;
  }
  Type *SourceTy = GepInst->getSourceElementType();
  StructType *StructTy = nullptr;
  ConstantInt *Idx;
  // Check if GEP calculates address from a struct array.
  if (isa<StructType>(SourceTy)) {
    StructTy = cast<StructType>(SourceTy);
    Idx = dyn_cast<ConstantInt>(GepInst->getOperand(1));
    if ((Idx == nullptr || Idx->getSExtValue() != 0) &&
        !shouldIgnoreStructType(StructTy) && StructTyMap.count(StructTy) != 0)
      Res |= insertCounterUpdate(I, StructTy, getArrayCounterIdx(StructTy));
  }
  // Iterate all (except the first and the last) idx within each GEP instruction
  // for possible nested struct field address calculation.
  for (unsigned i = 1; i < GepInst->getNumIndices(); ++i) {
    SmallVector<Value *, 8> IdxVec(GepInst->idx_begin(),
                                   GepInst->idx_begin() + i);
    Type *Ty = GetElementPtrInst::getIndexedType(SourceTy, IdxVec);
    unsigned CounterIdx = 0;
    if (isa<ArrayType>(Ty)) {
      ArrayType *ArrayTy = cast<ArrayType>(Ty);
      StructTy = dyn_cast<StructType>(ArrayTy->getElementType());
      if (shouldIgnoreStructType(StructTy) || StructTyMap.count(StructTy) == 0)
        continue;
      // The last counter for struct array access.
      CounterIdx = getArrayCounterIdx(StructTy);
    } else if (isa<StructType>(Ty)) {
      StructTy = cast<StructType>(Ty);
      if (shouldIgnoreStructType(StructTy) || StructTyMap.count(StructTy) == 0)
        continue;
      // Get the StructTy's subfield index.
      Idx = cast<ConstantInt>(GepInst->getOperand(i+1));
      assert(Idx->getSExtValue() >= 0 &&
             Idx->getSExtValue() < StructTy->getNumElements());
      CounterIdx = getFieldCounterIdx(StructTy) + Idx->getSExtValue();
    }
    Res |= insertCounterUpdate(I, StructTy, CounterIdx);
  }
  if (Res)
    ++NumInstrumentedGEPs;
  else
    ++NumIgnoredGEPs;
  return Res;
}

Value *PropagateJuliaAddrspaces::LiftPointer(Value *V, Type *LocTy, Instruction *InsertPt) {
    SmallVector<Value *, 4> Stack;
    Value *CurrentV = V;
    // Follow pointer casts back, see if we're based on a pointer in
    // an untracked address space, in which case we're allowed to drop
    // intermediate addrspace casts.
    while (true) {
        Stack.push_back(CurrentV);
        if (isa<BitCastInst>(CurrentV))
            CurrentV = cast<BitCastInst>(CurrentV)->getOperand(0);
        else if (isa<AddrSpaceCastInst>(CurrentV)) {
            CurrentV = cast<AddrSpaceCastInst>(CurrentV)->getOperand(0);
            if (!isSpecialAS(getValueAddrSpace(CurrentV)))
                break;
        }
        else if (isa<GetElementPtrInst>(CurrentV)) {
            if (LiftingMap.count(CurrentV)) {
                CurrentV = LiftingMap[CurrentV];
                break;
            } else if (Visited.count(CurrentV)) {
                return nullptr;
            }
            Visited.insert(CurrentV);
            CurrentV = cast<GetElementPtrInst>(CurrentV)->getOperand(0);
        } else
            break;
    }
    if (!CurrentV->getType()->isPointerTy())
        return nullptr;
    if (isSpecialAS(getValueAddrSpace(CurrentV)))
        return nullptr;
    // Ok, we're allowed to change the address space of this load, go back and
    // reconstitute any GEPs in the new address space.
    for (Value *V : llvm::reverse(Stack)) {
        GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V);
        if (!GEP)
            continue;
        if (LiftingMap.count(GEP)) {
            CurrentV = LiftingMap[GEP];
            continue;
        }
        GetElementPtrInst *NewGEP = cast<GetElementPtrInst>(GEP->clone());
        ToInsert.push_back(std::make_pair(NewGEP, GEP));
        Type *GEPTy = GEP->getSourceElementType();
        Type *NewRetTy = cast<PointerType>(GEP->getType())->getElementType()->getPointerTo(getValueAddrSpace(CurrentV));
        NewGEP->mutateType(NewRetTy);
        if (cast<PointerType>(CurrentV->getType())->getElementType() != GEPTy) {
            auto *BCI = new BitCastInst(CurrentV, GEPTy->getPointerTo());
            ToInsert.push_back(std::make_pair(BCI, NewGEP));
            CurrentV = BCI;
        }
        NewGEP->setOperand(GetElementPtrInst::getPointerOperandIndex(), CurrentV);
        LiftingMap[GEP] = NewGEP;
        CurrentV = NewGEP;
    }
    if (LocTy && cast<PointerType>(CurrentV->getType())->getElementType() != LocTy) {
        auto *BCI = new BitCastInst(CurrentV, LocTy->getPointerTo());
        ToInsert.push_back(std::make_pair(BCI, InsertPt));
        CurrentV = BCI;
    }
    return CurrentV;
}