Beispiel #1
0
/// Look through operations that will be free to find the earliest source of
/// this value.
///
/// @param ValLoc If V has aggegate type, we will be interested in a particular
/// scalar component. This records its address; the reverse of this list gives a
/// sequence of indices appropriate for an extractvalue to locate the important
/// value. This value is updated during the function and on exit will indicate
/// similar information for the Value returned.
///
/// @param DataBits If this function looks through truncate instructions, this
/// will record the smallest size attained.
static const Value *getNoopInput(const Value *V,
                                 SmallVectorImpl<unsigned> &ValLoc,
                                 unsigned &DataBits,
                                 const TargetLoweringBase &TLI) {
  while (true) {
    // Try to look through V1; if V1 is not an instruction, it can't be looked
    // through.
    const Instruction *I = dyn_cast<Instruction>(V);
    if (!I || I->getNumOperands() == 0) return V;
    const Value *NoopInput = 0;

    Value *Op = I->getOperand(0);
    if (isa<BitCastInst>(I)) {
      // Look through truly no-op bitcasts.
      if (isNoopBitcast(Op->getType(), I->getType(), TLI))
        NoopInput = Op;
    } else if (isa<GetElementPtrInst>(I)) {
      // Look through getelementptr
      if (cast<GetElementPtrInst>(I)->hasAllZeroIndices())
        NoopInput = Op;
    } else if (isa<IntToPtrInst>(I)) {
      // Look through inttoptr.
      // Make sure this isn't a truncating or extending cast.  We could
      // support this eventually, but don't bother for now.
      if (!isa<VectorType>(I->getType()) &&
          TLI.getPointerTy().getSizeInBits() ==
          cast<IntegerType>(Op->getType())->getBitWidth())
        NoopInput = Op;
    } else if (isa<PtrToIntInst>(I)) {
      // Look through ptrtoint.
      // Make sure this isn't a truncating or extending cast.  We could
      // support this eventually, but don't bother for now.
      if (!isa<VectorType>(I->getType()) &&
          TLI.getPointerTy().getSizeInBits() ==
          cast<IntegerType>(I->getType())->getBitWidth())
        NoopInput = Op;
    } else if (isa<TruncInst>(I) &&
               TLI.allowTruncateForTailCall(Op->getType(), I->getType())) {
      DataBits = std::min(DataBits, I->getType()->getPrimitiveSizeInBits());
      NoopInput = Op;
    } else if (isa<CallInst>(I)) {
      // Look through call (skipping callee)
      for (User::const_op_iterator i = I->op_begin(), e = I->op_end() - 1;
           i != e; ++i) {
        unsigned attrInd = i - I->op_begin() + 1;
        if (cast<CallInst>(I)->paramHasAttr(attrInd, Attribute::Returned) &&
            isNoopBitcast((*i)->getType(), I->getType(), TLI)) {
          NoopInput = *i;
          break;
        }
      }
    } else if (isa<InvokeInst>(I)) {
      // Look through invoke (skipping BB, BB, Callee)
      for (User::const_op_iterator i = I->op_begin(), e = I->op_end() - 3;
           i != e; ++i) {
        unsigned attrInd = i - I->op_begin() + 1;
        if (cast<InvokeInst>(I)->paramHasAttr(attrInd, Attribute::Returned) &&
            isNoopBitcast((*i)->getType(), I->getType(), TLI)) {
          NoopInput = *i;
          break;
        }
      }
    } else if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(V)) {
      // Value may come from either the aggregate or the scalar
      ArrayRef<unsigned> InsertLoc = IVI->getIndices();
      if (std::equal(InsertLoc.rbegin(), InsertLoc.rend(),
                     ValLoc.rbegin())) {
        // The type being inserted is a nested sub-type of the aggregate; we
        // have to remove those initial indices to get the location we're
        // interested in for the operand.
        ValLoc.resize(ValLoc.size() - InsertLoc.size());
        NoopInput = IVI->getInsertedValueOperand();
      } else {
        // The struct we're inserting into has the value we're interested in, no
        // change of address.
        NoopInput = Op;
      }
    } else if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(V)) {
      // The part we're interested in will inevitably be some sub-section of the
      // previous aggregate. Combine the two paths to obtain the true address of
      // our element.
      ArrayRef<unsigned> ExtractLoc = EVI->getIndices();
      std::copy(ExtractLoc.rbegin(), ExtractLoc.rend(),
                std::back_inserter(ValLoc));
      NoopInput = Op;
    }
    // Terminate if we couldn't find anything to look through.
    if (!NoopInput)
      return V;

    V = NoopInput;
  }
}
Beispiel #2
0
/// Look through operations that will be free to find the earliest source of
/// this value.
///
/// @param ValLoc If V has aggegate type, we will be interested in a particular
/// scalar component. This records its address; the reverse of this list gives a
/// sequence of indices appropriate for an extractvalue to locate the important
/// value. This value is updated during the function and on exit will indicate
/// similar information for the Value returned.
///
/// @param DataBits If this function looks through truncate instructions, this
/// will record the smallest size attained.
static const Value *getNoopInput(const Value *V,
                                 SmallVectorImpl<unsigned> &ValLoc,
                                 unsigned &DataBits,
                                 const TargetLoweringBase &TLI,
                                 const DataLayout &DL) {
  while (true) {
    // Try to look through V1; if V1 is not an instruction, it can't be looked
    // through.
    const Instruction *I = dyn_cast<Instruction>(V);
    if (!I || I->getNumOperands() == 0) return V;
    const Value *NoopInput = nullptr;

    Value *Op = I->getOperand(0);
    if (isa<BitCastInst>(I)) {
      // Look through truly no-op bitcasts.
      if (isNoopBitcast(Op->getType(), I->getType(), TLI))
        NoopInput = Op;
    } else if (isa<GetElementPtrInst>(I)) {
      // Look through getelementptr
      if (cast<GetElementPtrInst>(I)->hasAllZeroIndices())
        NoopInput = Op;
    } else if (isa<IntToPtrInst>(I)) {
      // Look through inttoptr.
      // Make sure this isn't a truncating or extending cast.  We could
      // support this eventually, but don't bother for now.
      if (!isa<VectorType>(I->getType()) &&
          DL.getPointerSizeInBits() ==
              cast<IntegerType>(Op->getType())->getBitWidth())
        NoopInput = Op;
    } else if (isa<PtrToIntInst>(I)) {
      // Look through ptrtoint.
      // Make sure this isn't a truncating or extending cast.  We could
      // support this eventually, but don't bother for now.
      if (!isa<VectorType>(I->getType()) &&
          DL.getPointerSizeInBits() ==
              cast<IntegerType>(I->getType())->getBitWidth())
        NoopInput = Op;
    } else if (isa<TruncInst>(I) &&
               TLI.allowTruncateForTailCall(Op->getType(), I->getType())) {
      DataBits = std::min(DataBits, I->getType()->getPrimitiveSizeInBits());
      NoopInput = Op;
    } else if (auto CS = ImmutableCallSite(I)) {
      const Value *ReturnedOp = CS.getReturnedArgOperand();
      if (ReturnedOp && isNoopBitcast(ReturnedOp->getType(), I->getType(), TLI))
        NoopInput = ReturnedOp;
    } else if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(V)) {
      // Value may come from either the aggregate or the scalar
      ArrayRef<unsigned> InsertLoc = IVI->getIndices();
      if (ValLoc.size() >= InsertLoc.size() &&
          std::equal(InsertLoc.begin(), InsertLoc.end(), ValLoc.rbegin())) {
        // The type being inserted is a nested sub-type of the aggregate; we
        // have to remove those initial indices to get the location we're
        // interested in for the operand.
        ValLoc.resize(ValLoc.size() - InsertLoc.size());
        NoopInput = IVI->getInsertedValueOperand();
      } else {
        // The struct we're inserting into has the value we're interested in, no
        // change of address.
        NoopInput = Op;
      }
    } else if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(V)) {
      // The part we're interested in will inevitably be some sub-section of the
      // previous aggregate. Combine the two paths to obtain the true address of
      // our element.
      ArrayRef<unsigned> ExtractLoc = EVI->getIndices();
      ValLoc.append(ExtractLoc.rbegin(), ExtractLoc.rend());
      NoopInput = Op;
    }
    // Terminate if we couldn't find anything to look through.
    if (!NoopInput)
      return V;

    V = NoopInput;
  }
}