C++ ConstantSDNode::getZExtValue方法代码示例

bool AMDGPUDAGToDAGISel::SelectADDRVTX_READ(SDValue Addr, SDValue &Base,
                                           SDValue &Offset) {
  ConstantSDNode * IMMOffset;

  if (Addr.getOpcode() == ISD::ADD
      && (IMMOffset = dyn_cast<ConstantSDNode>(Addr.getOperand(1)))
      && isInt<16>(IMMOffset->getZExtValue())) {

      Base = Addr.getOperand(0);
      Offset = CurDAG->getTargetConstant(IMMOffset->getZExtValue(), MVT::i32);
      return true;
  // If the pointer address is constant, we can move it to the offset field.
  } else if ((IMMOffset = dyn_cast<ConstantSDNode>(Addr))
             && isInt<16>(IMMOffset->getZExtValue())) {
    Base = CurDAG->getCopyFromReg(CurDAG->getEntryNode(),
                                  SDLoc(CurDAG->getEntryNode()),
                                  AMDGPU::ZERO, MVT::i32);
    Offset = CurDAG->getTargetConstant(IMMOffset->getZExtValue(), MVT::i32);
    return true;
  }

  // Default case, no offset
  Base = Addr;
  Offset = CurDAG->getTargetConstant(0, MVT::i32);
  return true;
}

// Match memory operand of the form [reg], [imm+reg], and [reg+imm]
bool PTXDAGToDAGISel::SelectADDRlocal(SDValue &Addr, SDValue &Base,
                                      SDValue &Offset) {
  //errs() << "SelectADDRlocal: ";
  //Addr.getNode()->dumpr();
  if (isa<FrameIndexSDNode>(Addr)) {
    Base = Addr;
    Offset = CurDAG->getTargetConstant(0, Addr.getValueType().getSimpleVT());
    //errs() << "Success\n";
    return true;
  }

  if (CurDAG->isBaseWithConstantOffset(Addr)) {
    Base = Addr.getOperand(0);
    if (!isa<FrameIndexSDNode>(Base)) {
      //errs() << "Failure\n";
      return false;
    }
    ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
    Offset = CurDAG->getTargetConstant(CN->getZExtValue(), MVT::i32);
    //errs() << "Offset: ";
    //Offset.getNode()->dumpr();
    //errs() << "Success\n";
    return true;
  }

  //errs() << "Failure\n";
  return false;
}

SDValue ARM64SelectionDAGInfo::EmitTargetCodeForMemset(
    SelectionDAG &DAG, SDLoc dl, SDValue Chain, SDValue Dst, SDValue Src,
    SDValue Size, unsigned Align, bool isVolatile,
    MachinePointerInfo DstPtrInfo) const {
  // Check to see if there is a specialized entry-point for memory zeroing.
  ConstantSDNode *V = dyn_cast<ConstantSDNode>(Src);
  ConstantSDNode *SizeValue = dyn_cast<ConstantSDNode>(Size);
  const char *bzeroEntry =
      (V && V->isNullValue()) ? Subtarget->getBZeroEntry() : 0;
  // For small size (< 256), it is not beneficial to use bzero
  // instead of memset.
  if (bzeroEntry && (!SizeValue || SizeValue->getZExtValue() > 256)) {
    const ARM64TargetLowering &TLI = *static_cast<const ARM64TargetLowering *>(
                                          DAG.getTarget().getTargetLowering());

    EVT IntPtr = TLI.getPointerTy();
    Type *IntPtrTy = getDataLayout()->getIntPtrType(*DAG.getContext());
    TargetLowering::ArgListTy Args;
    TargetLowering::ArgListEntry Entry;
    Entry.Node = Dst;
    Entry.Ty = IntPtrTy;
    Args.push_back(Entry);
    Entry.Node = Size;
    Args.push_back(Entry);
    TargetLowering::CallLoweringInfo CLI(
        Chain, Type::getVoidTy(*DAG.getContext()), false, false, false, false,
        0, CallingConv::C, /*isTailCall=*/false,
        /*doesNotRet=*/false, /*isReturnValueUsed=*/false,
        DAG.getExternalSymbol(bzeroEntry, IntPtr), Args, DAG, dl);
    std::pair<SDValue, SDValue> CallResult = TLI.LowerCallTo(CLI);
    return CallResult.second;
  }
  return SDValue();
}

/// ComplexPattern used on Cpu0InstrInfo
/// Used on Cpu0 Load/Store instructions
bool Cpu0DAGToDAGISel::
SelectAddr(SDNode *Parent, SDValue Addr, SDValue &Base, SDValue &Offset) {
  EVT ValTy = Addr.getValueType();

  // If Parent is an unaligned f32 load or store, select a (base + index)
  // floating point load/store instruction (luxc1 or suxc1).
  const LSBaseSDNode* LS = 0;

  if (Parent && (LS = dyn_cast<LSBaseSDNode>(Parent))) {
    EVT VT = LS->getMemoryVT();

    if (VT.getSizeInBits() / 8 > LS->getAlignment()) {
      assert(TLI.allowsUnalignedMemoryAccesses(VT) &&
             "Unaligned loads/stores not supported for this type.");
      if (VT == MVT::f32)
        return false;
    }
  }

  // if Address is FI, get the TargetFrameIndex.
  if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
    Base   = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
    Offset = CurDAG->getTargetConstant(0, ValTy);
    return true;
  }

  // on PIC code Load GA
  if (Addr.getOpcode() == Cpu0ISD::Wrapper) {
    Base   = Addr.getOperand(0);
    Offset = Addr.getOperand(1);
    return true;
  }

  if (TM.getRelocationModel() != Reloc::PIC_) {
    if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||
        Addr.getOpcode() == ISD::TargetGlobalAddress))
      return false;
  }
  
  // Addresses of the form FI+const or FI|const
  if (CurDAG->isBaseWithConstantOffset(Addr)) {
    ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
    if (isInt<16>(CN->getSExtValue())) {

      // If the first operand is a FI, get the TargetFI Node
      if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>
                                  (Addr.getOperand(0)))
        Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
      else
        Base = Addr.getOperand(0);

      Offset = CurDAG->getTargetConstant(CN->getZExtValue(), ValTy);
      return true;
    }
  }

  Base   = Addr;
  Offset = CurDAG->getTargetConstant(0, ValTy);
  return true;
}

bool AMDGPUDAGToDAGISel::SelectADDRIndirect(SDValue Addr, SDValue &Base,
                                            SDValue &Offset) {
  ConstantSDNode *C;

  if ((C = dyn_cast<ConstantSDNode>(Addr))) {
    Base = CurDAG->getRegister(AMDGPU::INDIRECT_BASE_ADDR, MVT::i32);
    Offset = CurDAG->getTargetConstant(C->getZExtValue(), MVT::i32);
  } else if ((Addr.getOpcode() == ISD::ADD || Addr.getOpcode() == ISD::OR) &&
            (C = dyn_cast<ConstantSDNode>(Addr.getOperand(1)))) {
    Base = Addr.getOperand(0);
    Offset = CurDAG->getTargetConstant(C->getZExtValue(), MVT::i32);
  } else {
    Base = Addr;
    Offset = CurDAG->getTargetConstant(0, MVT::i32);
  }

  return true;
}

// Return true if N is a undef or a constant.
// If N was undef, return a (i8imm 0) in Retval
// If N was imm, convert it to i8imm and return in Retval
// Note: The convert to i8imm is required, otherwise the
// pattern matcher inserts a bunch of IMOVi8rr to convert
// the imm to i8imm, and this causes instruction selection
// to fail.
bool NVPTXDAGToDAGISel::UndefOrImm(SDValue Op, SDValue N, SDValue &Retval) {
  if (!(N.getOpcode() == ISD::UNDEF) && !(N.getOpcode() == ISD::Constant))
    return false;

  if (N.getOpcode() == ISD::UNDEF)
    Retval = CurDAG->getTargetConstant(0, MVT::i8);
  else {
    ConstantSDNode *cn = cast<ConstantSDNode>(N.getNode());
    unsigned retval = cn->getZExtValue();
    Retval = CurDAG->getTargetConstant(retval, MVT::i8);
  }
  return true;
}

bool AArch64DAGToDAGISel::SelectLogicalImm(SDValue N, SDValue &Imm) {
  uint32_t Bits;
  uint32_t RegWidth = N.getValueType().getSizeInBits();

  ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N);
  if (!CN) return false;

  if (!A64Imms::isLogicalImm(RegWidth, CN->getZExtValue(), Bits))
    return false;

  Imm = CurDAG->getTargetConstant(Bits, MVT::i32);
  return true;
}

void MipsSEDAGToDAGISel::selectAddESubE(unsigned MOp, SDValue InFlag,
                                        SDValue CmpLHS, const SDLoc &DL,
                                        SDNode *Node) const {
    unsigned Opc = InFlag.getOpcode();
    (void)Opc;

    assert(((Opc == ISD::ADDC || Opc == ISD::ADDE) ||
            (Opc == ISD::SUBC || Opc == ISD::SUBE)) &&
           "(ADD|SUB)E flag operand must come from (ADD|SUB)C/E insn");

    unsigned SLTuOp = Mips::SLTu, ADDuOp = Mips::ADDu;
    if (Subtarget->isGP64bit()) {
        SLTuOp = Mips::SLTu64;
        ADDuOp = Mips::DADDu;
    }

    SDValue Ops[] = { CmpLHS, InFlag.getOperand(1) };
    SDValue LHS = Node->getOperand(0), RHS = Node->getOperand(1);
    EVT VT = LHS.getValueType();

    SDNode *Carry = CurDAG->getMachineNode(SLTuOp, DL, VT, Ops);

    if (Subtarget->isGP64bit()) {
        // On 64-bit targets, sltu produces an i64 but our backend currently says
        // that SLTu64 produces an i32. We need to fix this in the long run but for
        // now, just make the DAG type-correct by asserting the upper bits are zero.
        Carry = CurDAG->getMachineNode(Mips::SUBREG_TO_REG, DL, VT,
                                       CurDAG->getTargetConstant(0, DL, VT),
                                       SDValue(Carry, 0),
                                       CurDAG->getTargetConstant(Mips::sub_32, DL,
                                               VT));
    }

    // Generate a second addition only if we know that RHS is not a
    // constant-zero node.
    SDNode *AddCarry = Carry;
    ConstantSDNode *C = dyn_cast<ConstantSDNode>(RHS);
    if (!C || C->getZExtValue())
        AddCarry = CurDAG->getMachineNode(ADDuOp, DL, VT, SDValue(Carry, 0), RHS);

    CurDAG->SelectNodeTo(Node, MOp, VT, MVT::Glue, LHS, SDValue(AddCarry, 0));
}

SDValue HexagonSelectionDAGInfo::EmitTargetCodeForMemcpy(
    SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src,
    SDValue Size, unsigned Align, bool isVolatile, bool AlwaysInline,
    MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) const {
  ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
  if (AlwaysInline || (Align & 0x3) != 0 || !ConstantSize)
    return SDValue();

  uint64_t SizeVal = ConstantSize->getZExtValue();
  if (SizeVal < 32 || (SizeVal % 8) != 0)
    return SDValue();

  // Special case aligned memcpys with size >= 32 bytes and a multiple of 8.
  //
  const TargetLowering &TLI = *DAG.getSubtarget().getTargetLowering();
  TargetLowering::ArgListTy Args;
  TargetLowering::ArgListEntry Entry;
  Entry.Ty = DAG.getDataLayout().getIntPtrType(*DAG.getContext());
  Entry.Node = Dst;
  Args.push_back(Entry);
  Entry.Node = Src;
  Args.push_back(Entry);
  Entry.Node = Size;
  Args.push_back(Entry);

  const char *SpecialMemcpyName =
      "__hexagon_memcpy_likely_aligned_min32bytes_mult8bytes";

  TargetLowering::CallLoweringInfo CLI(DAG);
  CLI.setDebugLoc(dl)
      .setChain(Chain)
      .setCallee(TLI.getLibcallCallingConv(RTLIB::MEMCPY),
                 Type::getVoidTy(*DAG.getContext()),
                 DAG.getTargetExternalSymbol(
                     SpecialMemcpyName, TLI.getPointerTy(DAG.getDataLayout())),
                 std::move(Args))
      .setDiscardResult();

  std::pair<SDValue, SDValue> CallResult = TLI.LowerCallTo(CLI);
  return CallResult.second;
}

/// Match frameindex+offset and frameindex|offset
bool MipsSEDAGToDAGISel::selectAddrFrameIndexOffset(SDValue Addr, SDValue &Base,
                                                    SDValue &Offset,
                                                    unsigned OffsetBits) const {
  if (CurDAG->isBaseWithConstantOffset(Addr)) {
    ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
    if (isIntN(OffsetBits, CN->getSExtValue())) {
      EVT ValTy = Addr.getValueType();

      // If the first operand is a FI, get the TargetFI Node
      if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>
                                  (Addr.getOperand(0)))
        Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
      else
        Base = Addr.getOperand(0);

      Offset = CurDAG->getTargetConstant(CN->getZExtValue(), ValTy);
      return true;
    }
  }
  return false;
}

/// Used on microMIPS Load/Store unaligned instructions (12-bit offset)
bool MipsSEDAGToDAGISel::selectAddrRegImm12(SDValue Addr, SDValue &Base,
                                            SDValue &Offset) const {
  EVT ValTy = Addr.getValueType();

  // Addresses of the form FI+const or FI|const
  if (CurDAG->isBaseWithConstantOffset(Addr)) {
    ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
    if (isInt<12>(CN->getSExtValue())) {

      // If the first operand is a FI then get the TargetFI Node
      if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>
                                  (Addr.getOperand(0)))
        Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
      else
        Base = Addr.getOperand(0);

      Offset = CurDAG->getTargetConstant(CN->getZExtValue(), ValTy);
      return true;
    }
  }

  return false;
}

SDValue ARMSelectionDAGInfo::EmitTargetCodeForMemcpy(
    SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src,
    SDValue Size, unsigned Align, bool isVolatile, bool AlwaysInline,
    MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) const {
  const ARMSubtarget &Subtarget =
      DAG.getMachineFunction().getSubtarget<ARMSubtarget>();
  // Do repeated 4-byte loads and stores. To be improved.
  // This requires 4-byte alignment.
  if ((Align & 3) != 0)
    return SDValue();
  // This requires the copy size to be a constant, preferably
  // within a subtarget-specific limit.
  ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
  if (!ConstantSize)
    return EmitSpecializedLibcall(DAG, dl, Chain, Dst, Src, Size, Align,
                                  RTLIB::MEMCPY);
  uint64_t SizeVal = ConstantSize->getZExtValue();
  if (!AlwaysInline && SizeVal > Subtarget.getMaxInlineSizeThreshold())
    return EmitSpecializedLibcall(DAG, dl, Chain, Dst, Src, Size, Align,
                                  RTLIB::MEMCPY);

  unsigned BytesLeft = SizeVal & 3;
  unsigned NumMemOps = SizeVal >> 2;
  unsigned EmittedNumMemOps = 0;
  EVT VT = MVT::i32;
  unsigned VTSize = 4;
  unsigned i = 0;
  // Emit a maximum of 4 loads in Thumb1 since we have fewer registers
  const unsigned MaxLoadsInLDM = Subtarget.isThumb1Only() ? 4 : 6;
  SDValue TFOps[6];
  SDValue Loads[6];
  uint64_t SrcOff = 0, DstOff = 0;

  // FIXME: We should invent a VMEMCPY pseudo-instruction that lowers to
  // VLDM/VSTM and make this code emit it when appropriate. This would reduce
  // pressure on the general purpose registers. However this seems harder to map
  // onto the register allocator's view of the world.

  // The number of MEMCPY pseudo-instructions to emit. We use up to
  // MaxLoadsInLDM registers per mcopy, which will get lowered into ldm/stm
  // later on. This is a lower bound on the number of MEMCPY operations we must
  // emit.
  unsigned NumMEMCPYs = (NumMemOps + MaxLoadsInLDM - 1) / MaxLoadsInLDM;

  // Code size optimisation: do not inline memcpy if expansion results in
  // more instructions than the libary call.
  if (NumMEMCPYs > 1 && DAG.getMachineFunction().getFunction().optForMinSize()) {
    return SDValue();
  }

  SDVTList VTs = DAG.getVTList(MVT::i32, MVT::i32, MVT::Other, MVT::Glue);

  for (unsigned I = 0; I != NumMEMCPYs; ++I) {
    // Evenly distribute registers among MEMCPY operations to reduce register
    // pressure.
    unsigned NextEmittedNumMemOps = NumMemOps * (I + 1) / NumMEMCPYs;
    unsigned NumRegs = NextEmittedNumMemOps - EmittedNumMemOps;

    Dst = DAG.getNode(ARMISD::MEMCPY, dl, VTs, Chain, Dst, Src,
                      DAG.getConstant(NumRegs, dl, MVT::i32));
    Src = Dst.getValue(1);
    Chain = Dst.getValue(2);

    DstPtrInfo = DstPtrInfo.getWithOffset(NumRegs * VTSize);
    SrcPtrInfo = SrcPtrInfo.getWithOffset(NumRegs * VTSize);

    EmittedNumMemOps = NextEmittedNumMemOps;
  }

  if (BytesLeft == 0)
    return Chain;

  // Issue loads / stores for the trailing (1 - 3) bytes.
  auto getRemainingValueType = [](unsigned BytesLeft) {
    return (BytesLeft >= 2) ? MVT::i16 : MVT::i8;
  };
  auto getRemainingSize = [](unsigned BytesLeft) {
    return (BytesLeft >= 2) ? 2 : 1;
  };

  unsigned BytesLeftSave = BytesLeft;
  i = 0;
  while (BytesLeft) {
    VT = getRemainingValueType(BytesLeft);
    VTSize = getRemainingSize(BytesLeft);
    Loads[i] = DAG.getLoad(VT, dl, Chain,
                           DAG.getNode(ISD::ADD, dl, MVT::i32, Src,
                                       DAG.getConstant(SrcOff, dl, MVT::i32)),
                           SrcPtrInfo.getWithOffset(SrcOff));
    TFOps[i] = Loads[i].getValue(1);
    ++i;
    SrcOff += VTSize;
    BytesLeft -= VTSize;
  }
  Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
                      makeArrayRef(TFOps, i));

  i = 0;
  BytesLeft = BytesLeftSave;
  while (BytesLeft) {
//.........这里部分代码省略.........

SDValue
X86SelectionDAGInfo::EmitTargetCodeForMemcpy(SelectionDAG &DAG, SDLoc dl,
                                        SDValue Chain, SDValue Dst, SDValue Src,
                                        SDValue Size, unsigned Align,
                                        bool isVolatile, bool AlwaysInline,
                                         MachinePointerInfo DstPtrInfo,
                                         MachinePointerInfo SrcPtrInfo) const {
  // This requires the copy size to be a constant, preferably
  // within a subtarget-specific limit.
  ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
  if (!ConstantSize)
    return SDValue();
  uint64_t SizeVal = ConstantSize->getZExtValue();
  if (!AlwaysInline && SizeVal > Subtarget->getMaxInlineSizeThreshold())
    return SDValue();

  /// If not DWORD aligned, it is more efficient to call the library.  However
  /// if calling the library is not allowed (AlwaysInline), then soldier on as
  /// the code generated here is better than the long load-store sequence we
  /// would otherwise get.
  if (!AlwaysInline && (Align & 3) != 0)
    return SDValue();

  // If to a segment-relative address space, use the default lowering.
  if (DstPtrInfo.getAddrSpace() >= 256 ||
      SrcPtrInfo.getAddrSpace() >= 256)
    return SDValue();

  // ESI might be used as a base pointer, in that case we can't simply overwrite
  // the register.  Fall back to generic code.
  const X86RegisterInfo *TRI =
      static_cast<const X86RegisterInfo *>(DAG.getTarget().getRegisterInfo());
  if (TRI->hasBasePointer(DAG.getMachineFunction()) &&
      TRI->getBaseRegister() == X86::ESI)
    return SDValue();

  MVT AVT;
  if (Align & 1)
    AVT = MVT::i8;
  else if (Align & 2)
    AVT = MVT::i16;
  else if (Align & 4)
    // DWORD aligned
    AVT = MVT::i32;
  else
    // QWORD aligned
    AVT = Subtarget->is64Bit() ? MVT::i64 : MVT::i32;

  unsigned UBytes = AVT.getSizeInBits() / 8;
  unsigned CountVal = SizeVal / UBytes;
  SDValue Count = DAG.getIntPtrConstant(CountVal);
  unsigned BytesLeft = SizeVal % UBytes;

  SDValue InFlag;
  Chain  = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RCX :
                                                              X86::ECX,
                            Count, InFlag);
  InFlag = Chain.getValue(1);
  Chain  = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RDI :
                                                              X86::EDI,
                            Dst, InFlag);
  InFlag = Chain.getValue(1);
  Chain  = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RSI :
                                                              X86::ESI,
                            Src, InFlag);
  InFlag = Chain.getValue(1);

  SDVTList Tys = DAG.getVTList(MVT::Other, MVT::Glue);
  SDValue Ops[] = { Chain, DAG.getValueType(AVT), InFlag };
  SDValue RepMovs = DAG.getNode(X86ISD::REP_MOVS, dl, Tys, Ops);

  SmallVector<SDValue, 4> Results;
  Results.push_back(RepMovs);
  if (BytesLeft) {
    // Handle the last 1 - 7 bytes.
    unsigned Offset = SizeVal - BytesLeft;
    EVT DstVT = Dst.getValueType();
    EVT SrcVT = Src.getValueType();
    EVT SizeVT = Size.getValueType();
    Results.push_back(DAG.getMemcpy(Chain, dl,
                                    DAG.getNode(ISD::ADD, dl, DstVT, Dst,
                                                DAG.getConstant(Offset, DstVT)),
                                    DAG.getNode(ISD::ADD, dl, SrcVT, Src,
                                                DAG.getConstant(Offset, SrcVT)),
                                    DAG.getConstant(BytesLeft, SizeVT),
                                    Align, isVolatile, AlwaysInline,
                                    DstPtrInfo.getWithOffset(Offset),
                                    SrcPtrInfo.getWithOffset(Offset)));
  }

  return DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Results);
}

bool Mips16DAGToDAGISel::selectAddr16(
  SDNode *Parent, SDValue Addr, SDValue &Base, SDValue &Offset,
  SDValue &Alias) {
  EVT ValTy = Addr.getValueType();

  Alias = CurDAG->getTargetConstant(0, ValTy);

  // if Address is FI, get the TargetFrameIndex.
  if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
    Base   = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
    Offset = CurDAG->getTargetConstant(0, ValTy);
    getMips16SPRefReg(Parent, Alias);
    return true;
  }
  // on PIC code Load GA
  if (Addr.getOpcode() == MipsISD::Wrapper) {
    Base   = Addr.getOperand(0);
    Offset = Addr.getOperand(1);
    return true;
  }
  if (TM.getRelocationModel() != Reloc::PIC_) {
    if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||
        Addr.getOpcode() == ISD::TargetGlobalAddress))
      return false;
  }
  // Addresses of the form FI+const or FI|const
  if (CurDAG->isBaseWithConstantOffset(Addr)) {
    ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
    if (isInt<16>(CN->getSExtValue())) {

      // If the first operand is a FI, get the TargetFI Node
      if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>
                                  (Addr.getOperand(0))) {
        Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), ValTy);
        getMips16SPRefReg(Parent, Alias);
      }
      else
        Base = Addr.getOperand(0);

      Offset = CurDAG->getTargetConstant(CN->getZExtValue(), ValTy);
      return true;
    }
  }
  // Operand is a result from an ADD.
  if (Addr.getOpcode() == ISD::ADD) {
    // When loading from constant pools, load the lower address part in
    // the instruction itself. Example, instead of:
    //  lui $2, %hi($CPI1_0)
    //  addiu $2, $2, %lo($CPI1_0)
    //  lwc1 $f0, 0($2)
    // Generate:
    //  lui $2, %hi($CPI1_0)
    //  lwc1 $f0, %lo($CPI1_0)($2)
    if (Addr.getOperand(1).getOpcode() == MipsISD::Lo ||
        Addr.getOperand(1).getOpcode() == MipsISD::GPRel) {
      SDValue Opnd0 = Addr.getOperand(1).getOperand(0);
      if (isa<ConstantPoolSDNode>(Opnd0) || isa<GlobalAddressSDNode>(Opnd0) ||
          isa<JumpTableSDNode>(Opnd0)) {
        Base = Addr.getOperand(0);
        Offset = Opnd0;
        return true;
      }
    }

    // If an indexed floating point load/store can be emitted, return false.
    const LSBaseSDNode *LS = dyn_cast<LSBaseSDNode>(Parent);

    if (LS &&
        (LS->getMemoryVT() == MVT::f32 || LS->getMemoryVT() == MVT::f64) &&
        Subtarget.hasFPIdx())
      return false;
  }
  Base   = Addr;
  Offset = CurDAG->getTargetConstant(0, ValTy);
  return true;
}

SDValue
ARMSelectionDAGInfo::EmitTargetCodeForMemcpy(SelectionDAG &DAG, SDLoc dl,
                                             SDValue Chain,
                                             SDValue Dst, SDValue Src,
                                             SDValue Size, unsigned Align,
                                             bool isVolatile, bool AlwaysInline,
                                             MachinePointerInfo DstPtrInfo,
                                          MachinePointerInfo SrcPtrInfo) const {
  // Do repeated 4-byte loads and stores. To be improved.
  // This requires 4-byte alignment.
  if ((Align & 3) != 0)
    return SDValue();
  // This requires the copy size to be a constant, preferably
  // within a subtarget-specific limit.
  ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
  if (!ConstantSize)
    return SDValue();
  uint64_t SizeVal = ConstantSize->getZExtValue();
  if (!AlwaysInline && SizeVal > Subtarget->getMaxInlineSizeThreshold())
    return SDValue();

  unsigned BytesLeft = SizeVal & 3;
  unsigned NumMemOps = SizeVal >> 2;
  unsigned EmittedNumMemOps = 0;
  EVT VT = MVT::i32;
  unsigned VTSize = 4;
  unsigned i = 0;
  const unsigned MAX_LOADS_IN_LDM = 6;
  SDValue TFOps[MAX_LOADS_IN_LDM];
  SDValue Loads[MAX_LOADS_IN_LDM];
  uint64_t SrcOff = 0, DstOff = 0;

  // Emit up to MAX_LOADS_IN_LDM loads, then a TokenFactor barrier, then the
  // same number of stores.  The loads and stores will get combined into
  // ldm/stm later on.
  while (EmittedNumMemOps < NumMemOps) {
    for (i = 0;
         i < MAX_LOADS_IN_LDM && EmittedNumMemOps + i < NumMemOps; ++i) {
      Loads[i] = DAG.getLoad(VT, dl, Chain,
                             DAG.getNode(ISD::ADD, dl, MVT::i32, Src,
                                         DAG.getConstant(SrcOff, MVT::i32)),
                             SrcPtrInfo.getWithOffset(SrcOff), isVolatile,
                             false, false, 0);
      TFOps[i] = Loads[i].getValue(1);
      SrcOff += VTSize;
    }
    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, &TFOps[0], i);

    for (i = 0;
         i < MAX_LOADS_IN_LDM && EmittedNumMemOps + i < NumMemOps; ++i) {
      TFOps[i] = DAG.getStore(Chain, dl, Loads[i],
                              DAG.getNode(ISD::ADD, dl, MVT::i32, Dst,
                                          DAG.getConstant(DstOff, MVT::i32)),
                              DstPtrInfo.getWithOffset(DstOff),
                              isVolatile, false, 0);
      DstOff += VTSize;
    }
    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, &TFOps[0], i);

    EmittedNumMemOps += i;
  }

  if (BytesLeft == 0)
    return Chain;

  // Issue loads / stores for the trailing (1 - 3) bytes.
  unsigned BytesLeftSave = BytesLeft;
  i = 0;
  while (BytesLeft) {
    if (BytesLeft >= 2) {
      VT = MVT::i16;
      VTSize = 2;
    } else {
      VT = MVT::i8;
      VTSize = 1;
    }

    Loads[i] = DAG.getLoad(VT, dl, Chain,
                           DAG.getNode(ISD::ADD, dl, MVT::i32, Src,
                                       DAG.getConstant(SrcOff, MVT::i32)),
                           SrcPtrInfo.getWithOffset(SrcOff),
                           false, false, false, 0);
    TFOps[i] = Loads[i].getValue(1);
    ++i;
    SrcOff += VTSize;
    BytesLeft -= VTSize;
  }
  Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other, &TFOps[0], i);

  i = 0;
  BytesLeft = BytesLeftSave;
  while (BytesLeft) {
    if (BytesLeft >= 2) {
      VT = MVT::i16;
      VTSize = 2;
    } else {
      VT = MVT::i8;
      VTSize = 1;
    }

//.........这里部分代码省略.........