text: //===- llvm/CodeGen/SelectionDAGNodes.h - SelectionDAG Nodes ----*- C++ -*-===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  // This file declares the SDNode class and derived classes, which are used to
  // represent the nodes and operations present in a SelectionDAG.  These nodes
  // and operations are machine code level operations, with some similarities to
  // the GCC RTL representation.
  //
  // Clients should include the SelectionDAG.h file instead of this file directly.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_CODEGEN_SELECTIONDAGNODES_H
  #define LLVM_CODEGEN_SELECTIONDAGNODES_H
  
  #include "llvm/ADT/APFloat.h"
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/BitVector.h"
  #include "llvm/ADT/FoldingSet.h"
  #include "llvm/ADT/GraphTraits.h"
  #include "llvm/ADT/SmallPtrSet.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/ilist_node.h"
  #include "llvm/ADT/iterator.h"
  #include "llvm/ADT/iterator_range.h"
  #include "llvm/CodeGen/ISDOpcodes.h"
  #include "llvm/CodeGen/MachineMemOperand.h"
  #include "llvm/CodeGen/Register.h"
  #include "llvm/CodeGen/ValueTypes.h"
  #include "llvm/IR/Constants.h"
  #include "llvm/IR/DebugLoc.h"
  #include "llvm/IR/Instruction.h"
  #include "llvm/IR/Instructions.h"
  #include "llvm/IR/Metadata.h"
  #include "llvm/IR/Operator.h"
  #include "llvm/Support/AlignOf.h"
  #include "llvm/Support/AtomicOrdering.h"
  #include "llvm/Support/Casting.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/MachineValueType.h"
  #include "llvm/Support/TypeSize.h"
  #include <algorithm>
  #include <cassert>
  #include <climits>
  #include <cstddef>
  #include <cstdint>
  #include <cstring>
  #include <iterator>
  #include <string>
  #include <tuple>
  
  namespace llvm {
  
  class APInt;
  class Constant;
  template <typename T> struct DenseMapInfo;
  class GlobalValue;
  class MachineBasicBlock;
  class MachineConstantPoolValue;
  class MCSymbol;
  class raw_ostream;
  class SDNode;
  class SelectionDAG;
  class Type;
  class Value;
  
  void checkForCycles(const SDNode *N, const SelectionDAG *DAG = nullptr,
                      bool force = false);
  
  /// This represents a list of ValueType's that has been intern'd by
  /// a SelectionDAG.  Instances of this simple value class are returned by
  /// SelectionDAG::getVTList(...).
  ///
  struct SDVTList {
    const EVT *VTs;
    unsigned int NumVTs;
  };
  
  namespace ISD {
  
    /// Node predicates
  
    /// If N is a BUILD_VECTOR node whose elements are all the same constant or
    /// undefined, return true and return the constant value in \p SplatValue.
    bool isConstantSplatVector(const SDNode *N, APInt &SplatValue);
  
    /// Return true if the specified node is a BUILD_VECTOR where all of the
    /// elements are ~0 or undef.
    bool isBuildVectorAllOnes(const SDNode *N);
  
    /// Return true if the specified node is a BUILD_VECTOR where all of the
    /// elements are 0 or undef.
    bool isBuildVectorAllZeros(const SDNode *N);
  
    /// Return true if the specified node is a BUILD_VECTOR node of all
    /// ConstantSDNode or undef.
    bool isBuildVectorOfConstantSDNodes(const SDNode *N);
  
    /// Return true if the specified node is a BUILD_VECTOR node of all
    /// ConstantFPSDNode or undef.
    bool isBuildVectorOfConstantFPSDNodes(const SDNode *N);
  
    /// Return true if the node has at least one operand and all operands of the
    /// specified node are ISD::UNDEF.
    bool allOperandsUndef(const SDNode *N);
  
  } // end namespace ISD
  
  //===----------------------------------------------------------------------===//
  /// Unlike LLVM values, Selection DAG nodes may return multiple
  /// values as the result of a computation.  Many nodes return multiple values,
  /// from loads (which define a token and a return value) to ADDC (which returns
  /// a result and a carry value), to calls (which may return an arbitrary number
  /// of values).
  ///
  /// As such, each use of a SelectionDAG computation must indicate the node that
  /// computes it as well as which return value to use from that node.  This pair
  /// of information is represented with the SDValue value type.
  ///
  class SDValue {
    friend struct DenseMapInfo<SDValue>;
  
    SDNode *Node = nullptr; // The node defining the value we are using.
    unsigned ResNo = 0;     // Which return value of the node we are using.
  
  public:
    SDValue() = default;
    SDValue(SDNode *node, unsigned resno);
  
    /// get the index which selects a specific result in the SDNode
    unsigned getResNo() const { return ResNo; }
  
    /// get the SDNode which holds the desired result
    SDNode *getNode() const { return Node; }
  
    /// set the SDNode
    void setNode(SDNode *N) { Node = N; }
  
    inline SDNode *operator->() const { return Node; }
  
    bool operator==(const SDValue &O) const {
      return Node == O.Node && ResNo == O.ResNo;
    }
    bool operator!=(const SDValue &O) const {
      return !operator==(O);
    }
    bool operator<(const SDValue &O) const {
      return std::tie(Node, ResNo) < std::tie(O.Node, O.ResNo);
    }
    explicit operator bool() const {
      return Node != nullptr;
    }
  
    SDValue getValue(unsigned R) const {
      return SDValue(Node, R);
    }
  
    /// Return true if this node is an operand of N.
    bool isOperandOf(const SDNode *N) const;
  
    /// Return the ValueType of the referenced return value.
    inline EVT getValueType() const;
  
    /// Return the simple ValueType of the referenced return value.
    MVT getSimpleValueType() const {
      return getValueType().getSimpleVT();
    }
  
    /// Returns the size of the value in bits.
    ///
    /// If the value type is a scalable vector type, the scalable property will
    /// be set and the runtime size will be a positive integer multiple of the
    /// base size.
    TypeSize getValueSizeInBits() const {
      return getValueType().getSizeInBits();
    }
  
    TypeSize getScalarValueSizeInBits() const {
      return getValueType().getScalarType().getSizeInBits();
    }
  
    // Forwarding methods - These forward to the corresponding methods in SDNode.
    inline unsigned getOpcode() const;
    inline unsigned getNumOperands() const;
    inline const SDValue &getOperand(unsigned i) const;
    inline uint64_t getConstantOperandVal(unsigned i) const;
    inline const APInt &getConstantOperandAPInt(unsigned i) const;
    inline bool isTargetMemoryOpcode() const;
    inline bool isTargetOpcode() const;
    inline bool isMachineOpcode() const;
    inline bool isUndef() const;
    inline unsigned getMachineOpcode() const;
    inline const DebugLoc &getDebugLoc() const;
    inline void dump() const;
    inline void dump(const SelectionDAG *G) const;
    inline void dumpr() const;
    inline void dumpr(const SelectionDAG *G) const;
  
    /// Return true if this operand (which must be a chain) reaches the
    /// specified operand without crossing any side-effecting instructions.
    /// In practice, this looks through token factors and non-volatile loads.
    /// In order to remain efficient, this only
    /// looks a couple of nodes in, it does not do an exhaustive search.
    bool reachesChainWithoutSideEffects(SDValue Dest,
                                        unsigned Depth = 2) const;
  
    /// Return true if there are no nodes using value ResNo of Node.
    inline bool use_empty() const;
  
    /// Return true if there is exactly one node using value ResNo of Node.
    inline bool hasOneUse() const;
  };
  
  template<> struct DenseMapInfo<SDValue> {
    static inline SDValue getEmptyKey() {
      SDValue V;
      V.ResNo = -1U;
      return V;
    }
  
    static inline SDValue getTombstoneKey() {
      SDValue V;
      V.ResNo = -2U;
      return V;
    }
  
    static unsigned getHashValue(const SDValue &Val) {
      return ((unsigned)((uintptr_t)Val.getNode() >> 4) ^
              (unsigned)((uintptr_t)Val.getNode() >> 9)) + Val.getResNo();
    }
  
    static bool isEqual(const SDValue &LHS, const SDValue &RHS) {
      return LHS == RHS;
    }
  };
  
  /// Allow casting operators to work directly on
  /// SDValues as if they were SDNode*'s.
  template<> struct simplify_type<SDValue> {
    using SimpleType = SDNode *;
  
    static SimpleType getSimplifiedValue(SDValue &Val) {
      return Val.getNode();
    }
  };
  template<> struct simplify_type<const SDValue> {
    using SimpleType = /*const*/ SDNode *;
  
    static SimpleType getSimplifiedValue(const SDValue &Val) {
      return Val.getNode();
    }
  };
  
  /// Represents a use of a SDNode. This class holds an SDValue,
  /// which records the SDNode being used and the result number, a
  /// pointer to the SDNode using the value, and Next and Prev pointers,
  /// which link together all the uses of an SDNode.
  ///
  class SDUse {
    /// Val - The value being used.
    SDValue Val;
    /// User - The user of this value.
    SDNode *User = nullptr;
    /// Prev, Next - Pointers to the uses list of the SDNode referred by
    /// this operand.
    SDUse **Prev = nullptr;
    SDUse *Next = nullptr;
  
  public:
    SDUse() = default;
    SDUse(const SDUse &U) = delete;
    SDUse &operator=(const SDUse &) = delete;
  
    /// Normally SDUse will just implicitly convert to an SDValue that it holds.
    operator const SDValue&() const { return Val; }
  
    /// If implicit conversion to SDValue doesn't work, the get() method returns
    /// the SDValue.
    const SDValue &get() const { return Val; }
  
    /// This returns the SDNode that contains this Use.
    SDNode *getUser() { return User; }
  
    /// Get the next SDUse in the use list.
    SDUse *getNext() const { return Next; }
  
    /// Convenience function for get().getNode().
    SDNode *getNode() const { return Val.getNode(); }
    /// Convenience function for get().getResNo().
    unsigned getResNo() const { return Val.getResNo(); }
    /// Convenience function for get().getValueType().
    EVT getValueType() const { return Val.getValueType(); }
  
    /// Convenience function for get().operator==
    bool operator==(const SDValue &V) const {
      return Val == V;
    }
  
    /// Convenience function for get().operator!=
    bool operator!=(const SDValue &V) const {
      return Val != V;
    }
  
    /// Convenience function for get().operator<
    bool operator<(const SDValue &V) const {
      return Val < V;
    }
  
  private:
    friend class SelectionDAG;
    friend class SDNode;
    // TODO: unfriend HandleSDNode once we fix its operand handling.
    friend class HandleSDNode;
  
    void setUser(SDNode *p) { User = p; }
  
    /// Remove this use from its existing use list, assign it the
    /// given value, and add it to the new value's node's use list.
    inline void set(const SDValue &V);
    /// Like set, but only supports initializing a newly-allocated
    /// SDUse with a non-null value.
    inline void setInitial(const SDValue &V);
    /// Like set, but only sets the Node portion of the value,
    /// leaving the ResNo portion unmodified.
    inline void setNode(SDNode *N);
  
    void addToList(SDUse **List) {
      Next = *List;
      if (Next) Next->Prev = &Next;
      Prev = List;
      *List = this;
    }
  
    void removeFromList() {
      *Prev = Next;
      if (Next) Next->Prev = Prev;
    }
  };
  
  /// simplify_type specializations - Allow casting operators to work directly on
  /// SDValues as if they were SDNode*'s.
  template<> struct simplify_type<SDUse> {
    using SimpleType = SDNode *;
  
    static SimpleType getSimplifiedValue(SDUse &Val) {
      return Val.getNode();
    }
  };
  
  /// These are IR-level optimization flags that may be propagated to SDNodes.
  /// TODO: This data structure should be shared by the IR optimizer and the
  /// the backend.
  struct SDNodeFlags {
  private:
    // This bit is used to determine if the flags are in a defined state.
    // Flag bits can only be masked out during intersection if the masking flags
    // are defined.
    bool AnyDefined : 1;
  
    bool NoUnsignedWrap : 1;
    bool NoSignedWrap : 1;
    bool Exact : 1;
    bool NoNaNs : 1;
    bool NoInfs : 1;
    bool NoSignedZeros : 1;
    bool AllowReciprocal : 1;
    bool AllowContract : 1;
    bool ApproximateFuncs : 1;
    bool AllowReassociation : 1;
  
    // We assume instructions do not raise floating-point exceptions by default,
    // and only those marked explicitly may do so.  We could choose to represent
    // this via a positive "FPExcept" flags like on the MI level, but having a
    // negative "NoFPExcept" flag here (that defaults to true) makes the flag
    // intersection logic more straightforward.
    bool NoFPExcept : 1;
  
  public:
    /// Default constructor turns off all optimization flags.
    SDNodeFlags()
        : AnyDefined(false), NoUnsignedWrap(false), NoSignedWrap(false),
          Exact(false), NoNaNs(false), NoInfs(false),
          NoSignedZeros(false), AllowReciprocal(false),
          AllowContract(false), ApproximateFuncs(false),
          AllowReassociation(false), NoFPExcept(false) {}
  
    /// Propagate the fast-math-flags from an IR FPMathOperator.
    void copyFMF(const FPMathOperator &FPMO) {
      setNoNaNs(FPMO.hasNoNaNs());
      setNoInfs(FPMO.hasNoInfs());
      setNoSignedZeros(FPMO.hasNoSignedZeros());
      setAllowReciprocal(FPMO.hasAllowReciprocal());
      setAllowContract(FPMO.hasAllowContract());
      setApproximateFuncs(FPMO.hasApproxFunc());
      setAllowReassociation(FPMO.hasAllowReassoc());
    }
  
    /// Sets the state of the flags to the defined state.
    void setDefined() { AnyDefined = true; }
    /// Returns true if the flags are in a defined state.
    bool isDefined() const { return AnyDefined; }
  
    // These are mutators for each flag.
    void setNoUnsignedWrap(bool b) {
      setDefined();
      NoUnsignedWrap = b;
    }
    void setNoSignedWrap(bool b) {
      setDefined();
      NoSignedWrap = b;
    }
    void setExact(bool b) {
      setDefined();
      Exact = b;
    }
    void setNoNaNs(bool b) {
      setDefined();
      NoNaNs = b;
    }
    void setNoInfs(bool b) {
      setDefined();
      NoInfs = b;
    }
    void setNoSignedZeros(bool b) {
      setDefined();
      NoSignedZeros = b;
    }
    void setAllowReciprocal(bool b) {
      setDefined();
      AllowReciprocal = b;
    }
    void setAllowContract(bool b) {
      setDefined();
      AllowContract = b;
    }
    void setApproximateFuncs(bool b) {
      setDefined();
      ApproximateFuncs = b;
    }
    void setAllowReassociation(bool b) {
      setDefined();
      AllowReassociation = b;
    }
    void setNoFPExcept(bool b) {
      setDefined();
      NoFPExcept = b;
    }
  
    // These are accessors for each flag.
    bool hasNoUnsignedWrap() const { return NoUnsignedWrap; }
    bool hasNoSignedWrap() const { return NoSignedWrap; }
    bool hasExact() const { return Exact; }
    bool hasNoNaNs() const { return NoNaNs; }
    bool hasNoInfs() const { return NoInfs; }
    bool hasNoSignedZeros() const { return NoSignedZeros; }
    bool hasAllowReciprocal() const { return AllowReciprocal; }
    bool hasAllowContract() const { return AllowContract; }
    bool hasApproximateFuncs() const { return ApproximateFuncs; }
    bool hasAllowReassociation() const { return AllowReassociation; }
    bool hasNoFPExcept() const { return NoFPExcept; }
  
    /// Clear any flags in this flag set that aren't also set in Flags.
    /// If the given Flags are undefined then don't do anything.
    void intersectWith(const SDNodeFlags Flags) {
      if (!Flags.isDefined())
        return;
      NoUnsignedWrap &= Flags.NoUnsignedWrap;
      NoSignedWrap &= Flags.NoSignedWrap;
      Exact &= Flags.Exact;
      NoNaNs &= Flags.NoNaNs;
      NoInfs &= Flags.NoInfs;
      NoSignedZeros &= Flags.NoSignedZeros;
      AllowReciprocal &= Flags.AllowReciprocal;
      AllowContract &= Flags.AllowContract;
      ApproximateFuncs &= Flags.ApproximateFuncs;
      AllowReassociation &= Flags.AllowReassociation;
      NoFPExcept &= Flags.NoFPExcept;
    }
  };
  
  /// Represents one node in the SelectionDAG.
  ///
  class SDNode : public FoldingSetNode, public ilist_node<SDNode> {
  private:
    /// The operation that this node performs.
    int16_t NodeType;
  
  protected:
    // We define a set of mini-helper classes to help us interpret the bits in our
    // SubclassData.  These are designed to fit within a uint16_t so they pack
    // with NodeType.
  
  #if defined(_AIX) && (!defined(__GNUC__) || defined(__ibmxl__))
  // Except for GCC; by default, AIX compilers store bit-fields in 4-byte words
  // and give the `pack` pragma push semantics.
  #define BEGIN_TWO_BYTE_PACK() _Pragma("pack(2)")
  #define END_TWO_BYTE_PACK() _Pragma("pack(pop)")
  #else
  #define BEGIN_TWO_BYTE_PACK()
  #define END_TWO_BYTE_PACK()
  #endif
  
  BEGIN_TWO_BYTE_PACK()
    class SDNodeBitfields {
      friend class SDNode;
      friend class MemIntrinsicSDNode;
      friend class MemSDNode;
      friend class SelectionDAG;
  
      uint16_t HasDebugValue : 1;
      uint16_t IsMemIntrinsic : 1;
      uint16_t IsDivergent : 1;
    };
    enum { NumSDNodeBits = 3 };
  
    class ConstantSDNodeBitfields {
      friend class ConstantSDNode;
  
      uint16_t : NumSDNodeBits;
  
      uint16_t IsOpaque : 1;
    };
  
    class MemSDNodeBitfields {
      friend class MemSDNode;
      friend class MemIntrinsicSDNode;
      friend class AtomicSDNode;
  
      uint16_t : NumSDNodeBits;
  
      uint16_t IsVolatile : 1;
      uint16_t IsNonTemporal : 1;
      uint16_t IsDereferenceable : 1;
      uint16_t IsInvariant : 1;
    };
    enum { NumMemSDNodeBits = NumSDNodeBits + 4 };
  
    class LSBaseSDNodeBitfields {
      friend class LSBaseSDNode;
      friend class MaskedLoadStoreSDNode;
      friend class MaskedGatherScatterSDNode;
  
      uint16_t : NumMemSDNodeBits;
  
      // This storage is shared between disparate class hierarchies to hold an
      // enumeration specific to the class hierarchy in use.
      //   LSBaseSDNode => enum ISD::MemIndexedMode
      //   MaskedLoadStoreBaseSDNode => enum ISD::MemIndexedMode
      //   MaskedGatherScatterSDNode => enum ISD::MemIndexType
      uint16_t AddressingMode : 3;
    };
    enum { NumLSBaseSDNodeBits = NumMemSDNodeBits + 3 };
  
    class LoadSDNodeBitfields {
      friend class LoadSDNode;
      friend class MaskedLoadSDNode;
  
      uint16_t : NumLSBaseSDNodeBits;
  
      uint16_t ExtTy : 2; // enum ISD::LoadExtType
      uint16_t IsExpanding : 1;
    };
  
    class StoreSDNodeBitfields {
      friend class StoreSDNode;
      friend class MaskedStoreSDNode;
  
      uint16_t : NumLSBaseSDNodeBits;
  
      uint16_t IsTruncating : 1;
      uint16_t IsCompressing : 1;
    };
  
    union {
      char RawSDNodeBits[sizeof(uint16_t)];
      SDNodeBitfields SDNodeBits;
      ConstantSDNodeBitfields ConstantSDNodeBits;
      MemSDNodeBitfields MemSDNodeBits;
      LSBaseSDNodeBitfields LSBaseSDNodeBits;
      LoadSDNodeBitfields LoadSDNodeBits;
      StoreSDNodeBitfields StoreSDNodeBits;
    };
  END_TWO_BYTE_PACK()
  #undef BEGIN_TWO_BYTE_PACK
  #undef END_TWO_BYTE_PACK
  
    // RawSDNodeBits must cover the entirety of the union.  This means that all of
    // the union's members must have size <= RawSDNodeBits.  We write the RHS as
    // "2" instead of sizeof(RawSDNodeBits) because MSVC can't handle the latter.
    static_assert(sizeof(SDNodeBitfields) <= 2, "field too wide");
    static_assert(sizeof(ConstantSDNodeBitfields) <= 2, "field too wide");
    static_assert(sizeof(MemSDNodeBitfields) <= 2, "field too wide");
    static_assert(sizeof(LSBaseSDNodeBitfields) <= 2, "field too wide");
    static_assert(sizeof(LoadSDNodeBitfields) <= 2, "field too wide");
    static_assert(sizeof(StoreSDNodeBitfields) <= 2, "field too wide");
  
  private:
    friend class SelectionDAG;
    // TODO: unfriend HandleSDNode once we fix its operand handling.
    friend class HandleSDNode;
  
    /// Unique id per SDNode in the DAG.
    int NodeId = -1;
  
    /// The values that are used by this operation.
    SDUse *OperandList = nullptr;
  
    /// The types of the values this node defines.  SDNode's may
    /// define multiple values simultaneously.
    const EVT *ValueList;
  
    /// List of uses for this SDNode.
    SDUse *UseList = nullptr;
  
    /// The number of entries in the Operand/Value list.
    unsigned short NumOperands = 0;
    unsigned short NumValues;
  
    // The ordering of the SDNodes. It roughly corresponds to the ordering of the
    // original LLVM instructions.
    // This is used for turning off scheduling, because we'll forgo
    // the normal scheduling algorithms and output the instructions according to
    // this ordering.
    unsigned IROrder;
  
    /// Source line information.
    DebugLoc debugLoc;
  
    /// Return a pointer to the specified value type.
    static const EVT *getValueTypeList(EVT VT);
  
    SDNodeFlags Flags;
  
  public:
    /// Unique and persistent id per SDNode in the DAG.
    /// Used for debug printing.
    uint16_t PersistentId;
  
    //===--------------------------------------------------------------------===//
    //  Accessors
    //
  
    /// Return the SelectionDAG opcode value for this node. For
    /// pre-isel nodes (those for which isMachineOpcode returns false), these
    /// are the opcode values in the ISD and <target>ISD namespaces. For
    /// post-isel opcodes, see getMachineOpcode.
    unsigned getOpcode()  const { return (unsigned short)NodeType; }
  
    /// Test if this node has a target-specific opcode (in the
    /// \<target\>ISD namespace).
    bool isTargetOpcode() const { return NodeType >= ISD::BUILTIN_OP_END; }
  
    /// Test if this node has a target-specific opcode that may raise
    /// FP exceptions (in the \<target\>ISD namespace and greater than
    /// FIRST_TARGET_STRICTFP_OPCODE).  Note that all target memory
    /// opcode are currently automatically considered to possibly raise
    /// FP exceptions as well.
    bool isTargetStrictFPOpcode() const {
      return NodeType >= ISD::FIRST_TARGET_STRICTFP_OPCODE;
    }
  
    /// Test if this node has a target-specific
    /// memory-referencing opcode (in the \<target\>ISD namespace and
    /// greater than FIRST_TARGET_MEMORY_OPCODE).
    bool isTargetMemoryOpcode() const {
      return NodeType >= ISD::FIRST_TARGET_MEMORY_OPCODE;
    }
  
    /// Return true if the type of the node type undefined.
    bool isUndef() const { return NodeType == ISD::UNDEF; }
  
    /// Test if this node is a memory intrinsic (with valid pointer information).
    /// INTRINSIC_W_CHAIN and INTRINSIC_VOID nodes are sometimes created for
    /// non-memory intrinsics (with chains) that are not really instances of
    /// MemSDNode. For such nodes, we need some extra state to determine the
    /// proper classof relationship.
    bool isMemIntrinsic() const {
      return (NodeType == ISD::INTRINSIC_W_CHAIN ||
              NodeType == ISD::INTRINSIC_VOID) &&
             SDNodeBits.IsMemIntrinsic;
    }
  
    /// Test if this node is a strict floating point pseudo-op.
    bool isStrictFPOpcode() {
      switch (NodeType) {
        default:
          return false;
        case ISD::STRICT_FP16_TO_FP:
        case ISD::STRICT_FP_TO_FP16:
  #define DAG_INSTRUCTION(NAME, NARG, ROUND_MODE, INTRINSIC, DAGN)               \
        case ISD::STRICT_##DAGN:
  #include "llvm/IR/ConstrainedOps.def"
          return true;
      }
    }
  
    /// Test if this node has a post-isel opcode, directly
    /// corresponding to a MachineInstr opcode.
    bool isMachineOpcode() const { return NodeType < 0; }
  
    /// This may only be called if isMachineOpcode returns
    /// true. It returns the MachineInstr opcode value that the node's opcode
    /// corresponds to.
    unsigned getMachineOpcode() const {
      assert(isMachineOpcode() && "Not a MachineInstr opcode!");
      return ~NodeType;
    }
  
    bool getHasDebugValue() const { return SDNodeBits.HasDebugValue; }
    void setHasDebugValue(bool b) { SDNodeBits.HasDebugValue = b; }
  
    bool isDivergent() const { return SDNodeBits.IsDivergent; }
  
    /// Return true if there are no uses of this node.
    bool use_empty() const { return UseList == nullptr; }
  
    /// Return true if there is exactly one use of this node.
    bool hasOneUse() const {
      return !use_empty() && std::next(use_begin()) == use_end();
    }
  
    /// Return the number of uses of this node. This method takes
    /// time proportional to the number of uses.
    size_t use_size() const { return std::distance(use_begin(), use_end()); }
  
    /// Return the unique node id.
    int getNodeId() const { return NodeId; }
  
    /// Set unique node id.
    void setNodeId(int Id) { NodeId = Id; }
  
    /// Return the node ordering.
    unsigned getIROrder() const { return IROrder; }
  
    /// Set the node ordering.
    void setIROrder(unsigned Order) { IROrder = Order; }
  
    /// Return the source location info.
    const DebugLoc &getDebugLoc() const { return debugLoc; }
  
    /// Set source location info.  Try to avoid this, putting
    /// it in the constructor is preferable.
    void setDebugLoc(DebugLoc dl) { debugLoc = std::move(dl); }
  
    /// This class provides iterator support for SDUse
    /// operands that use a specific SDNode.
    class use_iterator
      : public std::iterator<std::forward_iterator_tag, SDUse, ptrdiff_t> {
      friend class SDNode;
  
      SDUse *Op = nullptr;
  
      explicit use_iterator(SDUse *op) : Op(op) {}
  
    public:
      using reference = std::iterator<std::forward_iterator_tag,
                                      SDUse, ptrdiff_t>::reference;
      using pointer = std::iterator<std::forward_iterator_tag,
                                    SDUse, ptrdiff_t>::pointer;
  
      use_iterator() = default;
      use_iterator(const use_iterator &I) : Op(I.Op) {}
  
      bool operator==(const use_iterator &x) const {
        return Op == x.Op;
      }
      bool operator!=(const use_iterator &x) const {
        return !operator==(x);
      }
  
      /// Return true if this iterator is at the end of uses list.
      bool atEnd() const { return Op == nullptr; }
  
      // Iterator traversal: forward iteration only.
      use_iterator &operator++() {          // Preincrement
        assert(Op && "Cannot increment end iterator!");
        Op = Op->getNext();
        return *this;
      }
  
      use_iterator operator++(int) {        // Postincrement
        use_iterator tmp = *this; ++*this; return tmp;
      }
  
      /// Retrieve a pointer to the current user node.
      SDNode *operator*() const {
        assert(Op && "Cannot dereference end iterator!");
        return Op->getUser();
      }
  
      SDNode *operator->() const { return operator*(); }
  
      SDUse &getUse() const { return *Op; }
  
      /// Retrieve the operand # of this use in its user.
      unsigned getOperandNo() const {
        assert(Op && "Cannot dereference end iterator!");
        return (unsigned)(Op - Op->getUser()->OperandList);
      }
    };
  
    /// Provide iteration support to walk over all uses of an SDNode.
    use_iterator use_begin() const {
      return use_iterator(UseList);
    }
  
    static use_iterator use_end() { return use_iterator(nullptr); }
  
    inline iterator_range<use_iterator> uses() {
      return make_range(use_begin(), use_end());
    }
    inline iterator_range<use_iterator> uses() const {
      return make_range(use_begin(), use_end());
    }
  
    /// Return true if there are exactly NUSES uses of the indicated value.
    /// This method ignores uses of other values defined by this operation.
    bool hasNUsesOfValue(unsigned NUses, unsigned Value) const;
  
    /// Return true if there are any use of the indicated value.
    /// This method ignores uses of other values defined by this operation.
    bool hasAnyUseOfValue(unsigned Value) const;
  
    /// Return true if this node is the only use of N.
    bool isOnlyUserOf(const SDNode *N) const;
  
    /// Return true if this node is an operand of N.
    bool isOperandOf(const SDNode *N) const;
  
    /// Return true if this node is a predecessor of N.
    /// NOTE: Implemented on top of hasPredecessor and every bit as
    /// expensive. Use carefully.
    bool isPredecessorOf(const SDNode *N) const {
      return N->hasPredecessor(this);
    }
  
    /// Return true if N is a predecessor of this node.
    /// N is either an operand of this node, or can be reached by recursively
    /// traversing up the operands.
    /// NOTE: This is an expensive method. Use it carefully.
    bool hasPredecessor(const SDNode *N) const;
  
    /// Returns true if N is a predecessor of any node in Worklist. This
    /// helper keeps Visited and Worklist sets externally to allow unions
    /// searches to be performed in parallel, caching of results across
    /// queries and incremental addition to Worklist. Stops early if N is
    /// found but will resume. Remember to clear Visited and Worklists
    /// if DAG changes. MaxSteps gives a maximum number of nodes to visit before
    /// giving up. The TopologicalPrune flag signals that positive NodeIds are
    /// topologically ordered (Operands have strictly smaller node id) and search
    /// can be pruned leveraging this.
    static bool hasPredecessorHelper(const SDNode *N,
                                     SmallPtrSetImpl<const SDNode *> &Visited,
                                     SmallVectorImpl<const SDNode *> &Worklist,
                                     unsigned int MaxSteps = 0,
                                     bool TopologicalPrune = false) {
      SmallVector<const SDNode *, 8> DeferredNodes;
      if (Visited.count(N))
        return true;
  
      // Node Id's are assigned in three places: As a topological
      // ordering (> 0), during legalization (results in values set to
      // 0), new nodes (set to -1). If N has a topolgical id then we
      // know that all nodes with ids smaller than it cannot be
      // successors and we need not check them. Filter out all node
      // that can't be matches. We add them to the worklist before exit
      // in case of multiple calls. Note that during selection the topological id
      // may be violated if a node's predecessor is selected before it. We mark
      // this at selection negating the id of unselected successors and
      // restricting topological pruning to positive ids.
  
      int NId = N->getNodeId();
      // If we Invalidated the Id, reconstruct original NId.
      if (NId < -1)
        NId = -(NId + 1);
  
      bool Found = false;
      while (!Worklist.empty()) {
        const SDNode *M = Worklist.pop_back_val();
        int MId = M->getNodeId();
        if (TopologicalPrune && M->getOpcode() != ISD::TokenFactor && (NId > 0) &&
            (MId > 0) && (MId < NId)) {
          DeferredNodes.push_back(M);
          continue;
        }
        for (const SDValue &OpV : M->op_values()) {
          SDNode *Op = OpV.getNode();
          if (Visited.insert(Op).second)
            Worklist.push_back(Op);
          if (Op == N)
            Found = true;
        }
        if (Found)
          break;
        if (MaxSteps != 0 && Visited.size() >= MaxSteps)
          break;
      }
      // Push deferred nodes back on worklist.
      Worklist.append(DeferredNodes.begin(), DeferredNodes.end());
      // If we bailed early, conservatively return found.
      if (MaxSteps != 0 && Visited.size() >= MaxSteps)
        return true;
      return Found;
    }
  
    /// Return true if all the users of N are contained in Nodes.
    /// NOTE: Requires at least one match, but doesn't require them all.
    static bool areOnlyUsersOf(ArrayRef<const SDNode *> Nodes, const SDNode *N);
  
    /// Return the number of values used by this operation.
    unsigned getNumOperands() const { return NumOperands; }
  
    /// Return the maximum number of operands that a SDNode can hold.
    static constexpr size_t getMaxNumOperands() {
      return std::numeric_limits<decltype(SDNode::NumOperands)>::max();
    }
  
    /// Helper method returns the integer value of a ConstantSDNode operand.
    inline uint64_t getConstantOperandVal(unsigned Num) const;
  
    /// Helper method returns the APInt of a ConstantSDNode operand.
    inline const APInt &getConstantOperandAPInt(unsigned Num) const;
  
    const SDValue &getOperand(unsigned Num) const {
      assert(Num < NumOperands && "Invalid child # of SDNode!");
      return OperandList[Num];
    }
  
    using op_iterator = SDUse *;
  
    op_iterator op_begin() const { return OperandList; }
    op_iterator op_end() const { return OperandList+NumOperands; }
    ArrayRef<SDUse> ops() const { return makeArrayRef(op_begin(), op_end()); }
  
    /// Iterator for directly iterating over the operand SDValue's.
    struct value_op_iterator
        : iterator_adaptor_base<value_op_iterator, op_iterator,
                                std::random_access_iterator_tag, SDValue,
                                ptrdiff_t, value_op_iterator *,
                                value_op_iterator *> {
      explicit value_op_iterator(SDUse *U = nullptr)
        : iterator_adaptor_base(U) {}
  
      const SDValue &operator*() const { return I->get(); }
    };
  
    iterator_range<value_op_iterator> op_values() const {
      return make_range(value_op_iterator(op_begin()),
                        value_op_iterator(op_end()));
    }
  
    SDVTList getVTList() const {
      SDVTList X = { ValueList, NumValues };
      return X;
    }
  
    /// If this node has a glue operand, return the node
    /// to which the glue operand points. Otherwise return NULL.
    SDNode *getGluedNode() const {
      if (getNumOperands() != 0 &&
          getOperand(getNumOperands()-1).getValueType() == MVT::Glue)
        return getOperand(getNumOperands()-1).getNode();
      return nullptr;
    }
  
    /// If this node has a glue value with a user, return
    /// the user (there is at most one). Otherwise return NULL.
    SDNode *getGluedUser() const {
      for (use_iterator UI = use_begin(), UE = use_end(); UI != UE; ++UI)
        if (UI.getUse().get().getValueType() == MVT::Glue)
          return *UI;
      return nullptr;
    }
  
    const SDNodeFlags getFlags() const { return Flags; }
    void setFlags(SDNodeFlags NewFlags) { Flags = NewFlags; }
  
    /// Clear any flags in this node that aren't also set in Flags.
    /// If Flags is not in a defined state then this has no effect.
    void intersectFlagsWith(const SDNodeFlags Flags);
  
    /// Return the number of values defined/returned by this operator.
    unsigned getNumValues() const { return NumValues; }
  
    /// Return the type of a specified result.
    EVT getValueType(unsigned ResNo) const {
      assert(ResNo < NumValues && "Illegal result number!");
      return ValueList[ResNo];
    }
  
    /// Return the type of a specified result as a simple type.
    MVT getSimpleValueType(unsigned ResNo) const {
      return getValueType(ResNo).getSimpleVT();
    }
  
    /// Returns MVT::getSizeInBits(getValueType(ResNo)).
    ///
    /// If the value type is a scalable vector type, the scalable property will
    /// be set and the runtime size will be a positive integer multiple of the
    /// base size.
    TypeSize getValueSizeInBits(unsigned ResNo) const {
      return getValueType(ResNo).getSizeInBits();
    }
  
    using value_iterator = const EVT *;
  
    value_iterator value_begin() const { return ValueList; }
    value_iterator value_end() const { return ValueList+NumValues; }
    iterator_range<value_iterator> values() const {
      return llvm::make_range(value_begin(), value_end());
    }
  
    /// Return the opcode of this operation for printing.
    std::string getOperationName(const SelectionDAG *G = nullptr) const;
    static const char* getIndexedModeName(ISD::MemIndexedMode AM);
    void print_types(raw_ostream &OS, const SelectionDAG *G) const;
    void print_details(raw_ostream &OS, const SelectionDAG *G) const;
    void print(raw_ostream &OS, const SelectionDAG *G = nullptr) const;
    void printr(raw_ostream &OS, const SelectionDAG *G = nullptr) const;
  
    /// Print a SelectionDAG node and all children down to
    /// the leaves.  The given SelectionDAG allows target-specific nodes
    /// to be printed in human-readable form.  Unlike printr, this will
    /// print the whole DAG, including children that appear multiple
    /// times.
    ///
    void printrFull(raw_ostream &O, const SelectionDAG *G = nullptr) const;
  
    /// Print a SelectionDAG node and children up to
    /// depth "depth."  The given SelectionDAG allows target-specific
    /// nodes to be printed in human-readable form.  Unlike printr, this
    /// will print children that appear multiple times wherever they are
    /// used.
    ///
    void printrWithDepth(raw_ostream &O, const SelectionDAG *G = nullptr,
                         unsigned depth = 100) const;
  
    /// Dump this node, for debugging.
    void dump() const;
  
    /// Dump (recursively) this node and its use-def subgraph.
    void dumpr() const;
  
    /// Dump this node, for debugging.
    /// The given SelectionDAG allows target-specific nodes to be printed
    /// in human-readable form.
    void dump(const SelectionDAG *G) const;
  
    /// Dump (recursively) this node and its use-def subgraph.
    /// The given SelectionDAG allows target-specific nodes to be printed
    /// in human-readable form.
    void dumpr(const SelectionDAG *G) const;
  
    /// printrFull to dbgs().  The given SelectionDAG allows
    /// target-specific nodes to be printed in human-readable form.
    /// Unlike dumpr, this will print the whole DAG, including children
    /// that appear multiple times.
    void dumprFull(const SelectionDAG *G = nullptr) const;
  
    /// printrWithDepth to dbgs().  The given
    /// SelectionDAG allows target-specific nodes to be printed in
    /// human-readable form.  Unlike dumpr, this will print children
    /// that appear multiple times wherever they are used.
    ///
    void dumprWithDepth(const SelectionDAG *G = nullptr,
                        unsigned depth = 100) const;
  
    /// Gather unique data for the node.
    void Profile(FoldingSetNodeID &ID) const;
  
    /// This method should only be used by the SDUse class.
    void addUse(SDUse &U) { U.addToList(&UseList); }
  
  protected:
    static SDVTList getSDVTList(EVT VT) {
      SDVTList Ret = { getValueTypeList(VT), 1 };
      return Ret;
    }
  
    /// Create an SDNode.
    ///
    /// SDNodes are created without any operands, and never own the operand
    /// storage. To add operands, see SelectionDAG::createOperands.
    SDNode(unsigned Opc, unsigned Order, DebugLoc dl, SDVTList VTs)
        : NodeType(Opc), ValueList(VTs.VTs), NumValues(VTs.NumVTs),
          IROrder(Order), debugLoc(std::move(dl)) {
      memset(&RawSDNodeBits, 0, sizeof(RawSDNodeBits));
      assert(debugLoc.hasTrivialDestructor() && "Expected trivial destructor");
      assert(NumValues == VTs.NumVTs &&
             "NumValues wasn't wide enough for its operands!");
    }
  
    /// Release the operands and set this node to have zero operands.
    void DropOperands();
  };
  
  /// Wrapper class for IR location info (IR ordering and DebugLoc) to be passed
  /// into SDNode creation functions.
  /// When an SDNode is created from the DAGBuilder, the DebugLoc is extracted
  /// from the original Instruction, and IROrder is the ordinal position of
  /// the instruction.
  /// When an SDNode is created after the DAG is being built, both DebugLoc and
  /// the IROrder are propagated from the original SDNode.
  /// So SDLoc class provides two constructors besides the default one, one to
  /// be used by the DAGBuilder, the other to be used by others.
  class SDLoc {
  private:
    DebugLoc DL;
    int IROrder = 0;
  
  public:
    SDLoc() = default;
    SDLoc(const SDNode *N) : DL(N->getDebugLoc()), IROrder(N->getIROrder()) {}
    SDLoc(const SDValue V) : SDLoc(V.getNode()) {}
    SDLoc(const Instruction *I, int Order) : IROrder(Order) {
      assert(Order >= 0 && "bad IROrder");
      if (I)
        DL = I->getDebugLoc();
    }
  
    unsigned getIROrder() const { return IROrder; }
    const DebugLoc &getDebugLoc() const { return DL; }
  };
  
  // Define inline functions from the SDValue class.
  
  inline SDValue::SDValue(SDNode *node, unsigned resno)
      : Node(node), ResNo(resno) {
    // Explicitly check for !ResNo to avoid use-after-free, because there are
    // callers that use SDValue(N, 0) with a deleted N to indicate successful
    // combines.
    assert((!Node || !ResNo || ResNo < Node->getNumValues()) &&
           "Invalid result number for the given node!");
    assert(ResNo < -2U && "Cannot use result numbers reserved for DenseMaps.");
  }
  
  inline unsigned SDValue::getOpcode() const {
    return Node->getOpcode();
  }
  
  inline EVT SDValue::getValueType() const {
    return Node->getValueType(ResNo);
  }
  
  inline unsigned SDValue::getNumOperands() const {
    return Node->getNumOperands();
  }
  
  inline const SDValue &SDValue::getOperand(unsigned i) const {
    return Node->getOperand(i);
  }
  
  inline uint64_t SDValue::getConstantOperandVal(unsigned i) const {
    return Node->getConstantOperandVal(i);
  }
  
  inline const APInt &SDValue::getConstantOperandAPInt(unsigned i) const {
    return Node->getConstantOperandAPInt(i);
  }
  
  inline bool SDValue::isTargetOpcode() const {
    return Node->isTargetOpcode();
  }
  
  inline bool SDValue::isTargetMemoryOpcode() const {
    return Node->isTargetMemoryOpcode();
  }
  
  inline bool SDValue::isMachineOpcode() const {
    return Node->isMachineOpcode();
  }
  
  inline unsigned SDValue::getMachineOpcode() const {
    return Node->getMachineOpcode();
  }
  
  inline bool SDValue::isUndef() const {
    return Node->isUndef();
  }
  
  inline bool SDValue::use_empty() const {
    return !Node->hasAnyUseOfValue(ResNo);
  }
  
  inline bool SDValue::hasOneUse() const {
    return Node->hasNUsesOfValue(1, ResNo);
  }
  
  inline const DebugLoc &SDValue::getDebugLoc() const {
    return Node->getDebugLoc();
  }
  
  inline void SDValue::dump() const {
    return Node->dump();
  }
  
  inline void SDValue::dump(const SelectionDAG *G) const {
    return Node->dump(G);
  }
  
  inline void SDValue::dumpr() const {
    return Node->dumpr();
  }
  
  inline void SDValue::dumpr(const SelectionDAG *G) const {
    return Node->dumpr(G);
  }
  
  // Define inline functions from the SDUse class.
  
  inline void SDUse::set(const SDValue &V) {
    if (Val.getNode()) removeFromList();
    Val = V;
    if (V.getNode()) V.getNode()->addUse(*this);
  }
  
  inline void SDUse::setInitial(const SDValue &V) {
    Val = V;
    V.getNode()->addUse(*this);
  }
  
  inline void SDUse::setNode(SDNode *N) {
    if (Val.getNode()) removeFromList();
    Val.setNode(N);
    if (N) N->addUse(*this);
  }
  
  /// This class is used to form a handle around another node that
  /// is persistent and is updated across invocations of replaceAllUsesWith on its
  /// operand.  This node should be directly created by end-users and not added to
  /// the AllNodes list.
  class HandleSDNode : public SDNode {
    SDUse Op;
  
  public:
    explicit HandleSDNode(SDValue X)
      : SDNode(ISD::HANDLENODE, 0, DebugLoc(), getSDVTList(MVT::Other)) {
      // HandleSDNodes are never inserted into the DAG, so they won't be
      // auto-numbered. Use ID 65535 as a sentinel.
      PersistentId = 0xffff;
  
      // Manually set up the operand list. This node type is special in that it's
      // always stack allocated and SelectionDAG does not manage its operands.
      // TODO: This should either (a) not be in the SDNode hierarchy, or (b) not
      // be so special.
      Op.setUser(this);
      Op.setInitial(X);
      NumOperands = 1;
      OperandList = &Op;
    }
    ~HandleSDNode();
  
    const SDValue &getValue() const { return Op; }
  };
  
  class AddrSpaceCastSDNode : public SDNode {
  private:
    unsigned SrcAddrSpace;
    unsigned DestAddrSpace;
  
  public:
    AddrSpaceCastSDNode(unsigned Order, const DebugLoc &dl, EVT VT,
                        unsigned SrcAS, unsigned DestAS);
  
    unsigned getSrcAddressSpace() const { return SrcAddrSpace; }
    unsigned getDestAddressSpace() const { return DestAddrSpace; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::ADDRSPACECAST;
    }
  };
  
  /// This is an abstract virtual class for memory operations.
  class MemSDNode : public SDNode {
  private:
    // VT of in-memory value.
    EVT MemoryVT;
  
  protected:
    /// Memory reference information.
    MachineMemOperand *MMO;
  
  public:
    MemSDNode(unsigned Opc, unsigned Order, const DebugLoc &dl, SDVTList VTs,
              EVT memvt, MachineMemOperand *MMO);
  
    bool readMem() const { return MMO->isLoad(); }
    bool writeMem() const { return MMO->isStore(); }
  
    /// Returns alignment and volatility of the memory access
    Align getOriginalAlign() const { return MMO->getBaseAlign(); }
    Align getAlign() const { return MMO->getAlign(); }
    LLVM_ATTRIBUTE_DEPRECATED(unsigned getOriginalAlignment() const,
                              "Use getOriginalAlign() instead") {
      return MMO->getBaseAlign().value();
    }
    // FIXME: Remove once transition to getAlign is over.
    unsigned getAlignment() const { return MMO->getAlign().value(); }
  
    /// Return the SubclassData value, without HasDebugValue. This contains an
    /// encoding of the volatile flag, as well as bits used by subclasses. This
    /// function should only be used to compute a FoldingSetNodeID value.
    /// The HasDebugValue bit is masked out because CSE map needs to match
    /// nodes with debug info with nodes without debug info. Same is about
    /// isDivergent bit.
    unsigned getRawSubclassData() const {
      uint16_t Data;
      union {
        char RawSDNodeBits[sizeof(uint16_t)];
        SDNodeBitfields SDNodeBits;
      };
      memcpy(&RawSDNodeBits, &this->RawSDNodeBits, sizeof(this->RawSDNodeBits));
      SDNodeBits.HasDebugValue = 0;
      SDNodeBits.IsDivergent = false;
      memcpy(&Data, &RawSDNodeBits, sizeof(RawSDNodeBits));
      return Data;
    }
  
    bool isVolatile() const { return MemSDNodeBits.IsVolatile; }
    bool isNonTemporal() const { return MemSDNodeBits.IsNonTemporal; }
    bool isDereferenceable() const { return MemSDNodeBits.IsDereferenceable; }
    bool isInvariant() const { return MemSDNodeBits.IsInvariant; }
  
    // Returns the offset from the location of the access.
    int64_t getSrcValueOffset() const { return MMO->getOffset(); }
  
    /// Returns the AA info that describes the dereference.
    AAMDNodes getAAInfo() const { return MMO->getAAInfo(); }
  
    /// Returns the Ranges that describes the dereference.
    const MDNode *getRanges() const { return MMO->getRanges(); }
  
    /// Returns the synchronization scope ID for this memory operation.
    SyncScope::ID getSyncScopeID() const { return MMO->getSyncScopeID(); }
  
    /// Return the atomic ordering requirements for this memory operation. For
    /// cmpxchg atomic operations, return the atomic ordering requirements when
    /// store occurs.
    AtomicOrdering getOrdering() const { return MMO->getOrdering(); }
  
    /// Return true if the memory operation ordering is Unordered or higher.
    bool isAtomic() const { return MMO->isAtomic(); }
  
    /// Returns true if the memory operation doesn't imply any ordering
    /// constraints on surrounding memory operations beyond the normal memory
    /// aliasing rules.
    bool isUnordered() const { return MMO->isUnordered(); }
  
    /// Returns true if the memory operation is neither atomic or volatile.
    bool isSimple() const { return !isAtomic() && !isVolatile(); }
  
    /// Return the type of the in-memory value.
    EVT getMemoryVT() const { return MemoryVT; }
  
    /// Return a MachineMemOperand object describing the memory
    /// reference performed by operation.
    MachineMemOperand *getMemOperand() const { return MMO; }
  
    const MachinePointerInfo &getPointerInfo() const {
      return MMO->getPointerInfo();
    }
  
    /// Return the address space for the associated pointer
    unsigned getAddressSpace() const {
      return getPointerInfo().getAddrSpace();
    }
  
    /// Update this MemSDNode's MachineMemOperand information
    /// to reflect the alignment of NewMMO, if it has a greater alignment.
    /// This must only be used when the new alignment applies to all users of
    /// this MachineMemOperand.
    void refineAlignment(const MachineMemOperand *NewMMO) {
      MMO->refineAlignment(NewMMO);
    }
  
    const SDValue &getChain() const { return getOperand(0); }
  
    const SDValue &getBasePtr() const {
      switch (getOpcode()) {
      case ISD::STORE:
      case ISD::MSTORE:
        return getOperand(2);
      case ISD::MGATHER:
      case ISD::MSCATTER:
        return getOperand(3);
      default:
        return getOperand(1);
      }
    }
  
    // Methods to support isa and dyn_cast
    static bool classof(const SDNode *N) {
      // For some targets, we lower some target intrinsics to a MemIntrinsicNode
      // with either an intrinsic or a target opcode.
      return N->getOpcode() == ISD::LOAD                ||
             N->getOpcode() == ISD::STORE               ||
             N->getOpcode() == ISD::PREFETCH            ||
             N->getOpcode() == ISD::ATOMIC_CMP_SWAP     ||
             N->getOpcode() == ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS ||
             N->getOpcode() == ISD::ATOMIC_SWAP         ||
             N->getOpcode() == ISD::ATOMIC_LOAD_ADD     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_SUB     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_AND     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_CLR     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_OR      ||
             N->getOpcode() == ISD::ATOMIC_LOAD_XOR     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_NAND    ||
             N->getOpcode() == ISD::ATOMIC_LOAD_MIN     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_MAX     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_UMIN    ||
             N->getOpcode() == ISD::ATOMIC_LOAD_UMAX    ||
             N->getOpcode() == ISD::ATOMIC_LOAD_FADD    ||
             N->getOpcode() == ISD::ATOMIC_LOAD_FSUB    ||
             N->getOpcode() == ISD::ATOMIC_LOAD         ||
             N->getOpcode() == ISD::ATOMIC_STORE        ||
             N->getOpcode() == ISD::MLOAD               ||
             N->getOpcode() == ISD::MSTORE              ||
             N->getOpcode() == ISD::MGATHER             ||
             N->getOpcode() == ISD::MSCATTER            ||
             N->isMemIntrinsic()                        ||
             N->isTargetMemoryOpcode();
    }
  };
  
  /// This is an SDNode representing atomic operations.
  class AtomicSDNode : public MemSDNode {
  public:
    AtomicSDNode(unsigned Opc, unsigned Order, const DebugLoc &dl, SDVTList VTL,
                 EVT MemVT, MachineMemOperand *MMO)
      : MemSDNode(Opc, Order, dl, VTL, MemVT, MMO) {
      assert(((Opc != ISD::ATOMIC_LOAD && Opc != ISD::ATOMIC_STORE) ||
              MMO->isAtomic()) && "then why are we using an AtomicSDNode?");
    }
  
    const SDValue &getBasePtr() const { return getOperand(1); }
    const SDValue &getVal() const { return getOperand(2); }
  
    /// Returns true if this SDNode represents cmpxchg atomic operation, false
    /// otherwise.
    bool isCompareAndSwap() const {
      unsigned Op = getOpcode();
      return Op == ISD::ATOMIC_CMP_SWAP ||
             Op == ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS;
    }
  
    /// For cmpxchg atomic operations, return the atomic ordering requirements
    /// when store does not occur.
    AtomicOrdering getFailureOrdering() const {
      assert(isCompareAndSwap() && "Must be cmpxchg operation");
      return MMO->getFailureOrdering();
    }
  
    // Methods to support isa and dyn_cast
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::ATOMIC_CMP_SWAP     ||
             N->getOpcode() == ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS ||
             N->getOpcode() == ISD::ATOMIC_SWAP         ||
             N->getOpcode() == ISD::ATOMIC_LOAD_ADD     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_SUB     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_AND     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_CLR     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_OR      ||
             N->getOpcode() == ISD::ATOMIC_LOAD_XOR     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_NAND    ||
             N->getOpcode() == ISD::ATOMIC_LOAD_MIN     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_MAX     ||
             N->getOpcode() == ISD::ATOMIC_LOAD_UMIN    ||
             N->getOpcode() == ISD::ATOMIC_LOAD_UMAX    ||
             N->getOpcode() == ISD::ATOMIC_LOAD_FADD    ||
             N->getOpcode() == ISD::ATOMIC_LOAD_FSUB    ||
             N->getOpcode() == ISD::ATOMIC_LOAD         ||
             N->getOpcode() == ISD::ATOMIC_STORE;
    }
  };
  
  /// This SDNode is used for target intrinsics that touch
  /// memory and need an associated MachineMemOperand. Its opcode may be
  /// INTRINSIC_VOID, INTRINSIC_W_CHAIN, PREFETCH, or a target-specific opcode
  /// with a value not less than FIRST_TARGET_MEMORY_OPCODE.
  class MemIntrinsicSDNode : public MemSDNode {
  public:
    MemIntrinsicSDNode(unsigned Opc, unsigned Order, const DebugLoc &dl,
                       SDVTList VTs, EVT MemoryVT, MachineMemOperand *MMO)
        : MemSDNode(Opc, Order, dl, VTs, MemoryVT, MMO) {
      SDNodeBits.IsMemIntrinsic = true;
    }
  
    // Methods to support isa and dyn_cast
    static bool classof(const SDNode *N) {
      // We lower some target intrinsics to their target opcode
      // early a node with a target opcode can be of this class
      return N->isMemIntrinsic()             ||
             N->getOpcode() == ISD::PREFETCH ||
             N->isTargetMemoryOpcode();
    }
  };
  
  /// This SDNode is used to implement the code generator
  /// support for the llvm IR shufflevector instruction.  It combines elements
  /// from two input vectors into a new input vector, with the selection and
  /// ordering of elements determined by an array of integers, referred to as
  /// the shuffle mask.  For input vectors of width N, mask indices of 0..N-1
  /// refer to elements from the LHS input, and indices from N to 2N-1 the RHS.
  /// An index of -1 is treated as undef, such that the code generator may put
  /// any value in the corresponding element of the result.
  class ShuffleVectorSDNode : public SDNode {
    // The memory for Mask is owned by the SelectionDAG's OperandAllocator, and
    // is freed when the SelectionDAG object is destroyed.
    const int *Mask;
  
  protected:
    friend class SelectionDAG;
  
    ShuffleVectorSDNode(EVT VT, unsigned Order, const DebugLoc &dl, const int *M)
        : SDNode(ISD::VECTOR_SHUFFLE, Order, dl, getSDVTList(VT)), Mask(M) {}
  
  public:
    ArrayRef<int> getMask() const {
      EVT VT = getValueType(0);
      return makeArrayRef(Mask, VT.getVectorNumElements());
    }
  
    int getMaskElt(unsigned Idx) const {
      assert(Idx < getValueType(0).getVectorNumElements() && "Idx out of range!");
      return Mask[Idx];
    }
  
    bool isSplat() const { return isSplatMask(Mask, getValueType(0)); }
  
    int getSplatIndex() const {
      assert(isSplat() && "Cannot get splat index for non-splat!");
      EVT VT = getValueType(0);
      for (unsigned i = 0, e = VT.getVectorNumElements(); i != e; ++i)
        if (Mask[i] >= 0)
          return Mask[i];
  
      // We can choose any index value here and be correct because all elements
      // are undefined. Return 0 for better potential for callers to simplify.
      return 0;
    }
  
    static bool isSplatMask(const int *Mask, EVT VT);
  
    /// Change values in a shuffle permute mask assuming
    /// the two vector operands have swapped position.
    static void commuteMask(MutableArrayRef<int> Mask) {
      unsigned NumElems = Mask.size();
      for (unsigned i = 0; i != NumElems; ++i) {
        int idx = Mask[i];
        if (idx < 0)
          continue;
        else if (idx < (int)NumElems)
          Mask[i] = idx + NumElems;
        else
          Mask[i] = idx - NumElems;
      }
    }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::VECTOR_SHUFFLE;
    }
  };
  
  class ConstantSDNode : public SDNode {
    friend class SelectionDAG;
  
    const ConstantInt *Value;
  
    ConstantSDNode(bool isTarget, bool isOpaque, const ConstantInt *val, EVT VT)
        : SDNode(isTarget ? ISD::TargetConstant : ISD::Constant, 0, DebugLoc(),
                 getSDVTList(VT)),
          Value(val) {
      ConstantSDNodeBits.IsOpaque = isOpaque;
    }
  
  public:
    const ConstantInt *getConstantIntValue() const { return Value; }
    const APInt &getAPIntValue() const { return Value->getValue(); }
    uint64_t getZExtValue() const { return Value->getZExtValue(); }
    int64_t getSExtValue() const { return Value->getSExtValue(); }
    uint64_t getLimitedValue(uint64_t Limit = UINT64_MAX) {
      return Value->getLimitedValue(Limit);
    }
    MaybeAlign getMaybeAlignValue() const { return Value->getMaybeAlignValue(); }
    Align getAlignValue() const { return Value->getAlignValue(); }
  
    bool isOne() const { return Value->isOne(); }
    bool isNullValue() const { return Value->isZero(); }
    bool isAllOnesValue() const { return Value->isMinusOne(); }
  
    bool isOpaque() const { return ConstantSDNodeBits.IsOpaque; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::Constant ||
             N->getOpcode() == ISD::TargetConstant;
    }
  };
  
  uint64_t SDNode::getConstantOperandVal(unsigned Num) const {
    return cast<ConstantSDNode>(getOperand(Num))->getZExtValue();
  }
  
  const APInt &SDNode::getConstantOperandAPInt(unsigned Num) const {
    return cast<ConstantSDNode>(getOperand(Num))->getAPIntValue();
  }
  
  class ConstantFPSDNode : public SDNode {
    friend class SelectionDAG;
  
    const ConstantFP *Value;
  
    ConstantFPSDNode(bool isTarget, const ConstantFP *val, EVT VT)
        : SDNode(isTarget ? ISD::TargetConstantFP : ISD::ConstantFP, 0,
                 DebugLoc(), getSDVTList(VT)),
          Value(val) {}
  
  public:
    const APFloat& getValueAPF() const { return Value->getValueAPF(); }
    const ConstantFP *getConstantFPValue() const { return Value; }
  
    /// Return true if the value is positive or negative zero.
    bool isZero() const { return Value->isZero(); }
  
    /// Return true if the value is a NaN.
    bool isNaN() const { return Value->isNaN(); }
  
    /// Return true if the value is an infinity
    bool isInfinity() const { return Value->isInfinity(); }
  
    /// Return true if the value is negative.
    bool isNegative() const { return Value->isNegative(); }
  
    /// We don't rely on operator== working on double values, as
    /// it returns true for things that are clearly not equal, like -0.0 and 0.0.
    /// As such, this method can be used to do an exact bit-for-bit comparison of
    /// two floating point values.
  
    /// We leave the version with the double argument here because it's just so
    /// convenient to write "2.0" and the like.  Without this function we'd
    /// have to duplicate its logic everywhere it's called.
    bool isExactlyValue(double V) const {
      return Value->getValueAPF().isExactlyValue(V);
    }
    bool isExactlyValue(const APFloat& V) const;
  
    static bool isValueValidForType(EVT VT, const APFloat& Val);
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::ConstantFP ||
             N->getOpcode() == ISD::TargetConstantFP;
    }
  };
  
  /// Returns true if \p V is a constant integer zero.
  bool isNullConstant(SDValue V);
  
  /// Returns true if \p V is an FP constant with a value of positive zero.
  bool isNullFPConstant(SDValue V);
  
  /// Returns true if \p V is an integer constant with all bits set.
  bool isAllOnesConstant(SDValue V);
  
  /// Returns true if \p V is a constant integer one.
  bool isOneConstant(SDValue V);
  
  /// Return the non-bitcasted source operand of \p V if it exists.
  /// If \p V is not a bitcasted value, it is returned as-is.
  SDValue peekThroughBitcasts(SDValue V);
  
  /// Return the non-bitcasted and one-use source operand of \p V if it exists.
  /// If \p V is not a bitcasted one-use value, it is returned as-is.
  SDValue peekThroughOneUseBitcasts(SDValue V);
  
  /// Return the non-extracted vector source operand of \p V if it exists.
  /// If \p V is not an extracted subvector, it is returned as-is.
  SDValue peekThroughExtractSubvectors(SDValue V);
  
  /// Returns true if \p V is a bitwise not operation. Assumes that an all ones
  /// constant is canonicalized to be operand 1.
  bool isBitwiseNot(SDValue V, bool AllowUndefs = false);
  
  /// Returns the SDNode if it is a constant splat BuildVector or constant int.
  ConstantSDNode *isConstOrConstSplat(SDValue N, bool AllowUndefs = false,
                                      bool AllowTruncation = false);
  
  /// Returns the SDNode if it is a demanded constant splat BuildVector or
  /// constant int.
  ConstantSDNode *isConstOrConstSplat(SDValue N, const APInt &DemandedElts,
                                      bool AllowUndefs = false,
                                      bool AllowTruncation = false);
  
  /// Returns the SDNode if it is a constant splat BuildVector or constant float.
  ConstantFPSDNode *isConstOrConstSplatFP(SDValue N, bool AllowUndefs = false);
  
  /// Returns the SDNode if it is a demanded constant splat BuildVector or
  /// constant float.
  ConstantFPSDNode *isConstOrConstSplatFP(SDValue N, const APInt &DemandedElts,
                                          bool AllowUndefs = false);
  
  /// Return true if the value is a constant 0 integer or a splatted vector of
  /// a constant 0 integer (with no undefs by default).
  /// Build vector implicit truncation is not an issue for null values.
  bool isNullOrNullSplat(SDValue V, bool AllowUndefs = false);
  
  /// Return true if the value is a constant 1 integer or a splatted vector of a
  /// constant 1 integer (with no undefs).
  /// Does not permit build vector implicit truncation.
  bool isOneOrOneSplat(SDValue V);
  
  /// Return true if the value is a constant -1 integer or a splatted vector of a
  /// constant -1 integer (with no undefs).
  /// Does not permit build vector implicit truncation.
  bool isAllOnesOrAllOnesSplat(SDValue V);
  
  class GlobalAddressSDNode : public SDNode {
    friend class SelectionDAG;
  
    const GlobalValue *TheGlobal;
    int64_t Offset;
    unsigned TargetFlags;
  
    GlobalAddressSDNode(unsigned Opc, unsigned Order, const DebugLoc &DL,
                        const GlobalValue *GA, EVT VT, int64_t o,
                        unsigned TF);
  
  public:
    const GlobalValue *getGlobal() const { return TheGlobal; }
    int64_t getOffset() const { return Offset; }
    unsigned getTargetFlags() const { return TargetFlags; }
    // Return the address space this GlobalAddress belongs to.
    unsigned getAddressSpace() const;
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::GlobalAddress ||
             N->getOpcode() == ISD::TargetGlobalAddress ||
             N->getOpcode() == ISD::GlobalTLSAddress ||
             N->getOpcode() == ISD::TargetGlobalTLSAddress;
    }
  };
  
  class FrameIndexSDNode : public SDNode {
    friend class SelectionDAG;
  
    int FI;
  
    FrameIndexSDNode(int fi, EVT VT, bool isTarg)
      : SDNode(isTarg ? ISD::TargetFrameIndex : ISD::FrameIndex,
        0, DebugLoc(), getSDVTList(VT)), FI(fi) {
    }
  
  public:
    int getIndex() const { return FI; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::FrameIndex ||
             N->getOpcode() == ISD::TargetFrameIndex;
    }
  };
  
  /// This SDNode is used for LIFETIME_START/LIFETIME_END values, which indicate
  /// the offet and size that are started/ended in the underlying FrameIndex.
  class LifetimeSDNode : public SDNode {
    friend class SelectionDAG;
    int64_t Size;
    int64_t Offset; // -1 if offset is unknown.
  
    LifetimeSDNode(unsigned Opcode, unsigned Order, const DebugLoc &dl,
                   SDVTList VTs, int64_t Size, int64_t Offset)
        : SDNode(Opcode, Order, dl, VTs), Size(Size), Offset(Offset) {}
  public:
    int64_t getFrameIndex() const {
      return cast<FrameIndexSDNode>(getOperand(1))->getIndex();
    }
  
    bool hasOffset() const { return Offset >= 0; }
    int64_t getOffset() const {
      assert(hasOffset() && "offset is unknown");
      return Offset;
    }
    int64_t getSize() const {
      assert(hasOffset() && "offset is unknown");
      return Size;
    }
  
    // Methods to support isa and dyn_cast
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::LIFETIME_START ||
             N->getOpcode() == ISD::LIFETIME_END;
    }
  };
  
  class JumpTableSDNode : public SDNode {
    friend class SelectionDAG;
  
    int JTI;
    unsigned TargetFlags;
  
    JumpTableSDNode(int jti, EVT VT, bool isTarg, unsigned TF)
      : SDNode(isTarg ? ISD::TargetJumpTable : ISD::JumpTable,
        0, DebugLoc(), getSDVTList(VT)), JTI(jti), TargetFlags(TF) {
    }
  
  public:
    int getIndex() const { return JTI; }
    unsigned getTargetFlags() const { return TargetFlags; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::JumpTable ||
             N->getOpcode() == ISD::TargetJumpTable;
    }
  };
  
  class ConstantPoolSDNode : public SDNode {
    friend class SelectionDAG;
  
    union {
      const Constant *ConstVal;
      MachineConstantPoolValue *MachineCPVal;
    } Val;
    int Offset;  // It's a MachineConstantPoolValue if top bit is set.
    Align Alignment; // Minimum alignment requirement of CP.
    unsigned TargetFlags;
  
    ConstantPoolSDNode(bool isTarget, const Constant *c, EVT VT, int o,
                       Align Alignment, unsigned TF)
        : SDNode(isTarget ? ISD::TargetConstantPool : ISD::ConstantPool, 0,
                 DebugLoc(), getSDVTList(VT)),
          Offset(o), Alignment(Alignment), TargetFlags(TF) {
      assert(Offset >= 0 && "Offset is too large");
      Val.ConstVal = c;
    }
  
    ConstantPoolSDNode(bool isTarget, MachineConstantPoolValue *v, EVT VT, int o,
                       Align Alignment, unsigned TF)
        : SDNode(isTarget ? ISD::TargetConstantPool : ISD::ConstantPool, 0,
                 DebugLoc(), getSDVTList(VT)),
          Offset(o), Alignment(Alignment), TargetFlags(TF) {
      assert(Offset >= 0 && "Offset is too large");
      Val.MachineCPVal = v;
      Offset |= 1 << (sizeof(unsigned)*CHAR_BIT-1);
    }
  
  public:
    bool isMachineConstantPoolEntry() const {
      return Offset < 0;
    }
  
    const Constant *getConstVal() const {
      assert(!isMachineConstantPoolEntry() && "Wrong constantpool type");
      return Val.ConstVal;
    }
  
    MachineConstantPoolValue *getMachineCPVal() const {
      assert(isMachineConstantPoolEntry() && "Wrong constantpool type");
      return Val.MachineCPVal;
    }
  
    int getOffset() const {
      return Offset & ~(1 << (sizeof(unsigned)*CHAR_BIT-1));
    }
  
    // Return the alignment of this constant pool object, which is either 0 (for
    // default alignment) or the desired value.
    Align getAlign() const { return Alignment; }
    unsigned getTargetFlags() const { return TargetFlags; }
  
    Type *getType() const;
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::ConstantPool ||
             N->getOpcode() == ISD::TargetConstantPool;
    }
  };
  
  /// Completely target-dependent object reference.
  class TargetIndexSDNode : public SDNode {
    friend class SelectionDAG;
  
    unsigned TargetFlags;
    int Index;
    int64_t Offset;
  
  public:
    TargetIndexSDNode(int Idx, EVT VT, int64_t Ofs, unsigned TF)
        : SDNode(ISD::TargetIndex, 0, DebugLoc(), getSDVTList(VT)),
          TargetFlags(TF), Index(Idx), Offset(Ofs) {}
  
    unsigned getTargetFlags() const { return TargetFlags; }
    int getIndex() const { return Index; }
    int64_t getOffset() const { return Offset; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::TargetIndex;
    }
  };
  
  class BasicBlockSDNode : public SDNode {
    friend class SelectionDAG;
  
    MachineBasicBlock *MBB;
  
    /// Debug info is meaningful and potentially useful here, but we create
    /// blocks out of order when they're jumped to, which makes it a bit
    /// harder.  Let's see if we need it first.
    explicit BasicBlockSDNode(MachineBasicBlock *mbb)
      : SDNode(ISD::BasicBlock, 0, DebugLoc(), getSDVTList(MVT::Other)), MBB(mbb)
    {}
  
  public:
    MachineBasicBlock *getBasicBlock() const { return MBB; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::BasicBlock;
    }
  };
  
  /// A "pseudo-class" with methods for operating on BUILD_VECTORs.
  class BuildVectorSDNode : public SDNode {
  public:
    // These are constructed as SDNodes and then cast to BuildVectorSDNodes.
    explicit BuildVectorSDNode() = delete;
  
    /// Check if this is a constant splat, and if so, find the
    /// smallest element size that splats the vector.  If MinSplatBits is
    /// nonzero, the element size must be at least that large.  Note that the
    /// splat element may be the entire vector (i.e., a one element vector).
    /// Returns the splat element value in SplatValue.  Any undefined bits in
    /// that value are zero, and the corresponding bits in the SplatUndef mask
    /// are set.  The SplatBitSize value is set to the splat element size in
    /// bits.  HasAnyUndefs is set to true if any bits in the vector are
    /// undefined.  isBigEndian describes the endianness of the target.
    bool isConstantSplat(APInt &SplatValue, APInt &SplatUndef,
                         unsigned &SplatBitSize, bool &HasAnyUndefs,
                         unsigned MinSplatBits = 0,
                         bool isBigEndian = false) const;
  
    /// Returns the demanded splatted value or a null value if this is not a
    /// splat.
    ///
    /// The DemandedElts mask indicates the elements that must be in the splat.
    /// If passed a non-null UndefElements bitvector, it will resize it to match
    /// the vector width and set the bits where elements are undef.
    SDValue getSplatValue(const APInt &DemandedElts,
                          BitVector *UndefElements = nullptr) const;
  
    /// Returns the splatted value or a null value if this is not a splat.
    ///
    /// If passed a non-null UndefElements bitvector, it will resize it to match
    /// the vector width and set the bits where elements are undef.
    SDValue getSplatValue(BitVector *UndefElements = nullptr) const;
  
    /// Returns the demanded splatted constant or null if this is not a constant
    /// splat.
    ///
    /// The DemandedElts mask indicates the elements that must be in the splat.
    /// If passed a non-null UndefElements bitvector, it will resize it to match
    /// the vector width and set the bits where elements are undef.
    ConstantSDNode *
    getConstantSplatNode(const APInt &DemandedElts,
                         BitVector *UndefElements = nullptr) const;
  
    /// Returns the splatted constant or null if this is not a constant
    /// splat.
    ///
    /// If passed a non-null UndefElements bitvector, it will resize it to match
    /// the vector width and set the bits where elements are undef.
    ConstantSDNode *
    getConstantSplatNode(BitVector *UndefElements = nullptr) const;
  
    /// Returns the demanded splatted constant FP or null if this is not a
    /// constant FP splat.
    ///
    /// The DemandedElts mask indicates the elements that must be in the splat.
    /// If passed a non-null UndefElements bitvector, it will resize it to match
    /// the vector width and set the bits where elements are undef.
    ConstantFPSDNode *
    getConstantFPSplatNode(const APInt &DemandedElts,
                           BitVector *UndefElements = nullptr) const;
  
    /// Returns the splatted constant FP or null if this is not a constant
    /// FP splat.
    ///
    /// If passed a non-null UndefElements bitvector, it will resize it to match
    /// the vector width and set the bits where elements are undef.
    ConstantFPSDNode *
    getConstantFPSplatNode(BitVector *UndefElements = nullptr) const;
  
    /// If this is a constant FP splat and the splatted constant FP is an
    /// exact power or 2, return the log base 2 integer value.  Otherwise,
    /// return -1.
    ///
    /// The BitWidth specifies the necessary bit precision.
    int32_t getConstantFPSplatPow2ToLog2Int(BitVector *UndefElements,
                                            uint32_t BitWidth) const;
  
    bool isConstant() const;
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::BUILD_VECTOR;
    }
  };
  
  /// An SDNode that holds an arbitrary LLVM IR Value. This is
  /// used when the SelectionDAG needs to make a simple reference to something
  /// in the LLVM IR representation.
  ///
  class SrcValueSDNode : public SDNode {
    friend class SelectionDAG;
  
    const Value *V;
  
    /// Create a SrcValue for a general value.
    explicit SrcValueSDNode(const Value *v)
      : SDNode(ISD::SRCVALUE, 0, DebugLoc(), getSDVTList(MVT::Other)), V(v) {}
  
  public:
    /// Return the contained Value.
    const Value *getValue() const { return V; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::SRCVALUE;
    }
  };
  
  class MDNodeSDNode : public SDNode {
    friend class SelectionDAG;
  
    const MDNode *MD;
  
    explicit MDNodeSDNode(const MDNode *md)
    : SDNode(ISD::MDNODE_SDNODE, 0, DebugLoc(), getSDVTList(MVT::Other)), MD(md)
    {}
  
  public:
    const MDNode *getMD() const { return MD; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::MDNODE_SDNODE;
    }
  };
  
  class RegisterSDNode : public SDNode {
    friend class SelectionDAG;
  
    Register Reg;
  
    RegisterSDNode(Register reg, EVT VT)
      : SDNode(ISD::Register, 0, DebugLoc(), getSDVTList(VT)), Reg(reg) {}
  
  public:
    Register getReg() const { return Reg; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::Register;
    }
  };
  
  class RegisterMaskSDNode : public SDNode {
    friend class SelectionDAG;
  
    // The memory for RegMask is not owned by the node.
    const uint32_t *RegMask;
  
    RegisterMaskSDNode(const uint32_t *mask)
      : SDNode(ISD::RegisterMask, 0, DebugLoc(), getSDVTList(MVT::Untyped)),
        RegMask(mask) {}
  
  public:
    const uint32_t *getRegMask() const { return RegMask; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::RegisterMask;
    }
  };
  
  class BlockAddressSDNode : public SDNode {
    friend class SelectionDAG;
  
    const BlockAddress *BA;
    int64_t Offset;
    unsigned TargetFlags;
  
    BlockAddressSDNode(unsigned NodeTy, EVT VT, const BlockAddress *ba,
                       int64_t o, unsigned Flags)
      : SDNode(NodeTy, 0, DebugLoc(), getSDVTList(VT)),
               BA(ba), Offset(o), TargetFlags(Flags) {}
  
  public:
    const BlockAddress *getBlockAddress() const { return BA; }
    int64_t getOffset() const { return Offset; }
    unsigned getTargetFlags() const { return TargetFlags; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::BlockAddress ||
             N->getOpcode() == ISD::TargetBlockAddress;
    }
  };
  
  class LabelSDNode : public SDNode {
    friend class SelectionDAG;
  
    MCSymbol *Label;
  
    LabelSDNode(unsigned Opcode, unsigned Order, const DebugLoc &dl, MCSymbol *L)
        : SDNode(Opcode, Order, dl, getSDVTList(MVT::Other)), Label(L) {
      assert(LabelSDNode::classof(this) && "not a label opcode");
    }
  
  public:
    MCSymbol *getLabel() const { return Label; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::EH_LABEL ||
             N->getOpcode() == ISD::ANNOTATION_LABEL;
    }
  };
  
  class ExternalSymbolSDNode : public SDNode {
    friend class SelectionDAG;
  
    const char *Symbol;
    unsigned TargetFlags;
  
    ExternalSymbolSDNode(bool isTarget, const char *Sym, unsigned TF, EVT VT)
        : SDNode(isTarget ? ISD::TargetExternalSymbol : ISD::ExternalSymbol, 0,
                 DebugLoc(), getSDVTList(VT)),
          Symbol(Sym), TargetFlags(TF) {}
  
  public:
    const char *getSymbol() const { return Symbol; }
    unsigned getTargetFlags() const { return TargetFlags; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::ExternalSymbol ||
             N->getOpcode() == ISD::TargetExternalSymbol;
    }
  };
  
  class MCSymbolSDNode : public SDNode {
    friend class SelectionDAG;
  
    MCSymbol *Symbol;
  
    MCSymbolSDNode(MCSymbol *Symbol, EVT VT)
        : SDNode(ISD::MCSymbol, 0, DebugLoc(), getSDVTList(VT)), Symbol(Symbol) {}
  
  public:
    MCSymbol *getMCSymbol() const { return Symbol; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::MCSymbol;
    }
  };
  
  class CondCodeSDNode : public SDNode {
    friend class SelectionDAG;
  
    ISD::CondCode Condition;
  
    explicit CondCodeSDNode(ISD::CondCode Cond)
      : SDNode(ISD::CONDCODE, 0, DebugLoc(), getSDVTList(MVT::Other)),
        Condition(Cond) {}
  
  public:
    ISD::CondCode get() const { return Condition; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::CONDCODE;
    }
  };
  
  /// This class is used to represent EVT's, which are used
  /// to parameterize some operations.
  class VTSDNode : public SDNode {
    friend class SelectionDAG;
  
    EVT ValueType;
  
    explicit VTSDNode(EVT VT)
      : SDNode(ISD::VALUETYPE, 0, DebugLoc(), getSDVTList(MVT::Other)),
        ValueType(VT) {}
  
  public:
    EVT getVT() const { return ValueType; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::VALUETYPE;
    }
  };
  
  /// Base class for LoadSDNode and StoreSDNode
  class LSBaseSDNode : public MemSDNode {
  public:
    LSBaseSDNode(ISD::NodeType NodeTy, unsigned Order, const DebugLoc &dl,
                 SDVTList VTs, ISD::MemIndexedMode AM, EVT MemVT,
                 MachineMemOperand *MMO)
        : MemSDNode(NodeTy, Order, dl, VTs, MemVT, MMO) {
      LSBaseSDNodeBits.AddressingMode = AM;
      assert(getAddressingMode() == AM && "Value truncated");
    }
  
    const SDValue &getOffset() const {
      return getOperand(getOpcode() == ISD::LOAD ? 2 : 3);
    }
  
    /// Return the addressing mode for this load or store:
    /// unindexed, pre-inc, pre-dec, post-inc, or post-dec.
    ISD::MemIndexedMode getAddressingMode() const {
      return static_cast<ISD::MemIndexedMode>(LSBaseSDNodeBits.AddressingMode);
    }
  
    /// Return true if this is a pre/post inc/dec load/store.
    bool isIndexed() const { return getAddressingMode() != ISD::UNINDEXED; }
  
    /// Return true if this is NOT a pre/post inc/dec load/store.
    bool isUnindexed() const { return getAddressingMode() == ISD::UNINDEXED; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::LOAD ||
             N->getOpcode() == ISD::STORE;
    }
  };
  
  /// This class is used to represent ISD::LOAD nodes.
  class LoadSDNode : public LSBaseSDNode {
    friend class SelectionDAG;
  
    LoadSDNode(unsigned Order, const DebugLoc &dl, SDVTList VTs,
               ISD::MemIndexedMode AM, ISD::LoadExtType ETy, EVT MemVT,
               MachineMemOperand *MMO)
        : LSBaseSDNode(ISD::LOAD, Order, dl, VTs, AM, MemVT, MMO) {
      LoadSDNodeBits.ExtTy = ETy;
      assert(readMem() && "Load MachineMemOperand is not a load!");
      assert(!writeMem() && "Load MachineMemOperand is a store!");
    }
  
  public:
    /// Return whether this is a plain node,
    /// or one of the varieties of value-extending loads.
    ISD::LoadExtType getExtensionType() const {
      return static_cast<ISD::LoadExtType>(LoadSDNodeBits.ExtTy);
    }
  
    const SDValue &getBasePtr() const { return getOperand(1); }
    const SDValue &getOffset() const { return getOperand(2); }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::LOAD;
    }
  };
  
  /// This class is used to represent ISD::STORE nodes.
  class StoreSDNode : public LSBaseSDNode {
    friend class SelectionDAG;
  
    StoreSDNode(unsigned Order, const DebugLoc &dl, SDVTList VTs,
                ISD::MemIndexedMode AM, bool isTrunc, EVT MemVT,
                MachineMemOperand *MMO)
        : LSBaseSDNode(ISD::STORE, Order, dl, VTs, AM, MemVT, MMO) {
      StoreSDNodeBits.IsTruncating = isTrunc;
      assert(!readMem() && "Store MachineMemOperand is a load!");
      assert(writeMem() && "Store MachineMemOperand is not a store!");
    }
  
  public:
    /// Return true if the op does a truncation before store.
    /// For integers this is the same as doing a TRUNCATE and storing the result.
    /// For floats, it is the same as doing an FP_ROUND and storing the result.
    bool isTruncatingStore() const { return StoreSDNodeBits.IsTruncating; }
    void setTruncatingStore(bool Truncating) {
      StoreSDNodeBits.IsTruncating = Truncating;
    }
  
    const SDValue &getValue() const { return getOperand(1); }
    const SDValue &getBasePtr() const { return getOperand(2); }
    const SDValue &getOffset() const { return getOperand(3); }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::STORE;
    }
  };
  
  /// This base class is used to represent MLOAD and MSTORE nodes
  class MaskedLoadStoreSDNode : public MemSDNode {
  public:
    friend class SelectionDAG;
  
    MaskedLoadStoreSDNode(ISD::NodeType NodeTy, unsigned Order,
                          const DebugLoc &dl, SDVTList VTs,
                          ISD::MemIndexedMode AM, EVT MemVT,
                          MachineMemOperand *MMO)
        : MemSDNode(NodeTy, Order, dl, VTs, MemVT, MMO) {
      LSBaseSDNodeBits.AddressingMode = AM;
      assert(getAddressingMode() == AM && "Value truncated");
    }
  
    // MaskedLoadSDNode (Chain, ptr, offset, mask, passthru)
    // MaskedStoreSDNode (Chain, data, ptr, offset, mask)
    // Mask is a vector of i1 elements
    const SDValue &getOffset() const {
      return getOperand(getOpcode() == ISD::MLOAD ? 2 : 3);
    }
    const SDValue &getMask() const {
      return getOperand(getOpcode() == ISD::MLOAD ? 3 : 4);
    }
  
    /// Return the addressing mode for this load or store:
    /// unindexed, pre-inc, pre-dec, post-inc, or post-dec.
    ISD::MemIndexedMode getAddressingMode() const {
      return static_cast<ISD::MemIndexedMode>(LSBaseSDNodeBits.AddressingMode);
    }
  
    /// Return true if this is a pre/post inc/dec load/store.
    bool isIndexed() const { return getAddressingMode() != ISD::UNINDEXED; }
  
    /// Return true if this is NOT a pre/post inc/dec load/store.
    bool isUnindexed() const { return getAddressingMode() == ISD::UNINDEXED; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::MLOAD ||
             N->getOpcode() == ISD::MSTORE;
    }
  };
  
  /// This class is used to represent an MLOAD node
  class MaskedLoadSDNode : public MaskedLoadStoreSDNode {
  public:
    friend class SelectionDAG;
  
    MaskedLoadSDNode(unsigned Order, const DebugLoc &dl, SDVTList VTs,
                     ISD::MemIndexedMode AM, ISD::LoadExtType ETy,
                     bool IsExpanding, EVT MemVT, MachineMemOperand *MMO)
        : MaskedLoadStoreSDNode(ISD::MLOAD, Order, dl, VTs, AM, MemVT, MMO) {
      LoadSDNodeBits.ExtTy = ETy;
      LoadSDNodeBits.IsExpanding = IsExpanding;
    }
  
    ISD::LoadExtType getExtensionType() const {
      return static_cast<ISD::LoadExtType>(LoadSDNodeBits.ExtTy);
    }
  
    const SDValue &getBasePtr() const { return getOperand(1); }
    const SDValue &getOffset() const { return getOperand(2); }
    const SDValue &getMask() const { return getOperand(3); }
    const SDValue &getPassThru() const { return getOperand(4); }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::MLOAD;
    }
  
    bool isExpandingLoad() const { return LoadSDNodeBits.IsExpanding; }
  };
  
  /// This class is used to represent an MSTORE node
  class MaskedStoreSDNode : public MaskedLoadStoreSDNode {
  public:
    friend class SelectionDAG;
  
    MaskedStoreSDNode(unsigned Order, const DebugLoc &dl, SDVTList VTs,
                      ISD::MemIndexedMode AM, bool isTrunc, bool isCompressing,
                      EVT MemVT, MachineMemOperand *MMO)
        : MaskedLoadStoreSDNode(ISD::MSTORE, Order, dl, VTs, AM, MemVT, MMO) {
      StoreSDNodeBits.IsTruncating = isTrunc;
      StoreSDNodeBits.IsCompressing = isCompressing;
    }
  
    /// Return true if the op does a truncation before store.
    /// For integers this is the same as doing a TRUNCATE and storing the result.
    /// For floats, it is the same as doing an FP_ROUND and storing the result.
    bool isTruncatingStore() const { return StoreSDNodeBits.IsTruncating; }
  
    /// Returns true if the op does a compression to the vector before storing.
    /// The node contiguously stores the active elements (integers or floats)
    /// in src (those with their respective bit set in writemask k) to unaligned
    /// memory at base_addr.
    bool isCompressingStore() const { return StoreSDNodeBits.IsCompressing; }
  
    const SDValue &getValue() const { return getOperand(1); }
    const SDValue &getBasePtr() const { return getOperand(2); }
    const SDValue &getOffset() const { return getOperand(3); }
    const SDValue &getMask() const { return getOperand(4); }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::MSTORE;
    }
  };
  
  /// This is a base class used to represent
  /// MGATHER and MSCATTER nodes
  ///
  class MaskedGatherScatterSDNode : public MemSDNode {
  public:
    friend class SelectionDAG;
  
    MaskedGatherScatterSDNode(ISD::NodeType NodeTy, unsigned Order,
                              const DebugLoc &dl, SDVTList VTs, EVT MemVT,
                              MachineMemOperand *MMO, ISD::MemIndexType IndexType)
        : MemSDNode(NodeTy, Order, dl, VTs, MemVT, MMO) {
      LSBaseSDNodeBits.AddressingMode = IndexType;
      assert(getIndexType() == IndexType && "Value truncated");
    }
  
    /// How is Index applied to BasePtr when computing addresses.
    ISD::MemIndexType getIndexType() const {
      return static_cast<ISD::MemIndexType>(LSBaseSDNodeBits.AddressingMode);
    }
    bool isIndexScaled() const {
      return (getIndexType() == ISD::SIGNED_SCALED) ||
             (getIndexType() == ISD::UNSIGNED_SCALED);
    }
    bool isIndexSigned() const {
      return (getIndexType() == ISD::SIGNED_SCALED) ||
             (getIndexType() == ISD::SIGNED_UNSCALED);
    }
  
    // In the both nodes address is Op1, mask is Op2:
    // MaskedGatherSDNode  (Chain, passthru, mask, base, index, scale)
    // MaskedScatterSDNode (Chain, value, mask, base, index, scale)
    // Mask is a vector of i1 elements
    const SDValue &getBasePtr() const { return getOperand(3); }
    const SDValue &getIndex()   const { return getOperand(4); }
    const SDValue &getMask()    const { return getOperand(2); }
    const SDValue &getScale()   const { return getOperand(5); }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::MGATHER ||
             N->getOpcode() == ISD::MSCATTER;
    }
  };
  
  /// This class is used to represent an MGATHER node
  ///
  class MaskedGatherSDNode : public MaskedGatherScatterSDNode {
  public:
    friend class SelectionDAG;
  
    MaskedGatherSDNode(unsigned Order, const DebugLoc &dl, SDVTList VTs,
                       EVT MemVT, MachineMemOperand *MMO,
                       ISD::MemIndexType IndexType)
        : MaskedGatherScatterSDNode(ISD::MGATHER, Order, dl, VTs, MemVT, MMO,
                                    IndexType) {}
  
    const SDValue &getPassThru() const { return getOperand(1); }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::MGATHER;
    }
  };
  
  /// This class is used to represent an MSCATTER node
  ///
  class MaskedScatterSDNode : public MaskedGatherScatterSDNode {
  public:
    friend class SelectionDAG;
  
    MaskedScatterSDNode(unsigned Order, const DebugLoc &dl, SDVTList VTs,
                        EVT MemVT, MachineMemOperand *MMO,
                        ISD::MemIndexType IndexType)
        : MaskedGatherScatterSDNode(ISD::MSCATTER, Order, dl, VTs, MemVT, MMO,
                                    IndexType) {}
  
    const SDValue &getValue() const { return getOperand(1); }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::MSCATTER;
    }
  };
  
  /// An SDNode that represents everything that will be needed
  /// to construct a MachineInstr. These nodes are created during the
  /// instruction selection proper phase.
  ///
  /// Note that the only supported way to set the `memoperands` is by calling the
  /// `SelectionDAG::setNodeMemRefs` function as the memory management happens
  /// inside the DAG rather than in the node.
  class MachineSDNode : public SDNode {
  private:
    friend class SelectionDAG;
  
    MachineSDNode(unsigned Opc, unsigned Order, const DebugLoc &DL, SDVTList VTs)
        : SDNode(Opc, Order, DL, VTs) {}
  
    // We use a pointer union between a single `MachineMemOperand` pointer and
    // a pointer to an array of `MachineMemOperand` pointers. This is null when
    // the number of these is zero, the single pointer variant used when the
    // number is one, and the array is used for larger numbers.
    //
    // The array is allocated via the `SelectionDAG`'s allocator and so will
    // always live until the DAG is cleaned up and doesn't require ownership here.
    //
    // We can't use something simpler like `TinyPtrVector` here because `SDNode`
    // subclasses aren't managed in a conforming C++ manner. See the comments on
    // `SelectionDAG::MorphNodeTo` which details what all goes on, but the
    // constraint here is that these don't manage memory with their constructor or
    // destructor and can be initialized to a good state even if they start off
    // uninitialized.
    PointerUnion<MachineMemOperand *, MachineMemOperand **> MemRefs = {};
  
    // Note that this could be folded into the above `MemRefs` member if doing so
    // is advantageous at some point. We don't need to store this in most cases.
    // However, at the moment this doesn't appear to make the allocation any
    // smaller and makes the code somewhat simpler to read.
    int NumMemRefs = 0;
  
  public:
    using mmo_iterator = ArrayRef<MachineMemOperand *>::const_iterator;
  
    ArrayRef<MachineMemOperand *> memoperands() const {
      // Special case the common cases.
      if (NumMemRefs == 0)
        return {};
      if (NumMemRefs == 1)
        return makeArrayRef(MemRefs.getAddrOfPtr1(), 1);
  
      // Otherwise we have an actual array.
      return makeArrayRef(MemRefs.get<MachineMemOperand **>(), NumMemRefs);
    }
    mmo_iterator memoperands_begin() const { return memoperands().begin(); }
    mmo_iterator memoperands_end() const { return memoperands().end(); }
    bool memoperands_empty() const { return memoperands().empty(); }
  
    /// Clear out the memory reference descriptor list.
    void clearMemRefs() {
      MemRefs = nullptr;
      NumMemRefs = 0;
    }
  
    static bool classof(const SDNode *N) {
      return N->isMachineOpcode();
    }
  };
  
  /// An SDNode that records if a register contains a value that is guaranteed to
  /// be aligned accordingly.
  class AssertAlignSDNode : public SDNode {
    Align Alignment;
  
  public:
    AssertAlignSDNode(unsigned Order, const DebugLoc &DL, EVT VT, Align A)
        : SDNode(ISD::AssertAlign, Order, DL, getSDVTList(VT)), Alignment(A) {}
  
    Align getAlign() const { return Alignment; }
  
    static bool classof(const SDNode *N) {
      return N->getOpcode() == ISD::AssertAlign;
    }
  };
  
  class SDNodeIterator : public std::iterator<std::forward_iterator_tag,
                                              SDNode, ptrdiff_t> {
    const SDNode *Node;
    unsigned Operand;
  
    SDNodeIterator(const SDNode *N, unsigned Op) : Node(N), Operand(Op) {}
  
  public:
    bool operator==(const SDNodeIterator& x) const {
      return Operand == x.Operand;
    }
    bool operator!=(const SDNodeIterator& x) const { return !operator==(x); }
  
    pointer operator*() const {
      return Node->getOperand(Operand).getNode();
    }
    pointer operator->() const { return operator*(); }
  
    SDNodeIterator& operator++() {                // Preincrement
      ++Operand;
      return *this;
    }
    SDNodeIterator operator++(int) { // Postincrement
      SDNodeIterator tmp = *this; ++*this; return tmp;
    }
    size_t operator-(SDNodeIterator Other) const {
      assert(Node == Other.Node &&
             "Cannot compare iterators of two different nodes!");
      return Operand - Other.Operand;
    }
  
    static SDNodeIterator begin(const SDNode *N) { return SDNodeIterator(N, 0); }
    static SDNodeIterator end  (const SDNode *N) {
      return SDNodeIterator(N, N->getNumOperands());
    }
  
    unsigned getOperand() const { return Operand; }
    const SDNode *getNode() const { return Node; }
  };
  
  template <> struct GraphTraits<SDNode*> {
    using NodeRef = SDNode *;
    using ChildIteratorType = SDNodeIterator;
  
    static NodeRef getEntryNode(SDNode *N) { return N; }
  
    static ChildIteratorType child_begin(NodeRef N) {
      return SDNodeIterator::begin(N);
    }
  
    static ChildIteratorType child_end(NodeRef N) {
      return SDNodeIterator::end(N);
    }
  };
  
  /// A representation of the largest SDNode, for use in sizeof().
  ///
  /// This needs to be a union because the largest node differs on 32 bit systems
  /// with 4 and 8 byte pointer alignment, respectively.
  using LargestSDNode = AlignedCharArrayUnion<AtomicSDNode, TargetIndexSDNode,
                                              BlockAddressSDNode,
                                              GlobalAddressSDNode>;
  
  /// The SDNode class with the greatest alignment requirement.
  using MostAlignedSDNode = GlobalAddressSDNode;
  
  namespace ISD {
  
    /// Returns true if the specified node is a non-extending and unindexed load.
    inline bool isNormalLoad(const SDNode *N) {
      const LoadSDNode *Ld = dyn_cast<LoadSDNode>(N);
      return Ld && Ld->getExtensionType() == ISD::NON_EXTLOAD &&
        Ld->getAddressingMode() == ISD::UNINDEXED;
    }
  
    /// Returns true if the specified node is a non-extending load.
    inline bool isNON_EXTLoad(const SDNode *N) {
      return isa<LoadSDNode>(N) &&
        cast<LoadSDNode>(N)->getExtensionType() == ISD::NON_EXTLOAD;
    }
  
    /// Returns true if the specified node is a EXTLOAD.
    inline bool isEXTLoad(const SDNode *N) {
      return isa<LoadSDNode>(N) &&
        cast<LoadSDNode>(N)->getExtensionType() == ISD::EXTLOAD;
    }
  
    /// Returns true if the specified node is a SEXTLOAD.
    inline bool isSEXTLoad(const SDNode *N) {
      return isa<LoadSDNode>(N) &&
        cast<LoadSDNode>(N)->getExtensionType() == ISD::SEXTLOAD;
    }
  
    /// Returns true if the specified node is a ZEXTLOAD.
    inline bool isZEXTLoad(const SDNode *N) {
      return isa<LoadSDNode>(N) &&
        cast<LoadSDNode>(N)->getExtensionType() == ISD::ZEXTLOAD;
    }
  
    /// Returns true if the specified node is an unindexed load.
    inline bool isUNINDEXEDLoad(const SDNode *N) {
      return isa<LoadSDNode>(N) &&
        cast<LoadSDNode>(N)->getAddressingMode() == ISD::UNINDEXED;
    }
  
    /// Returns true if the specified node is a non-truncating
    /// and unindexed store.
    inline bool isNormalStore(const SDNode *N) {
      const StoreSDNode *St = dyn_cast<StoreSDNode>(N);
      return St && !St->isTruncatingStore() &&
        St->getAddressingMode() == ISD::UNINDEXED;
    }
  
    /// Returns true if the specified node is a non-truncating store.
    inline bool isNON_TRUNCStore(const SDNode *N) {
      return isa<StoreSDNode>(N) && !cast<StoreSDNode>(N)->isTruncatingStore();
    }
  
    /// Returns true if the specified node is a truncating store.
    inline bool isTRUNCStore(const SDNode *N) {
      return isa<StoreSDNode>(N) && cast<StoreSDNode>(N)->isTruncatingStore();
    }
  
    /// Returns true if the specified node is an unindexed store.
    inline bool isUNINDEXEDStore(const SDNode *N) {
      return isa<StoreSDNode>(N) &&
        cast<StoreSDNode>(N)->getAddressingMode() == ISD::UNINDEXED;
    }
  
    /// Attempt to match a unary predicate against a scalar/splat constant or
    /// every element of a constant BUILD_VECTOR.
    /// If AllowUndef is true, then UNDEF elements will pass nullptr to Match.
    bool matchUnaryPredicate(SDValue Op,
                             std::function<bool(ConstantSDNode *)> Match,
                             bool AllowUndefs = false);
  
    /// Attempt to match a binary predicate against a pair of scalar/splat
    /// constants or every element of a pair of constant BUILD_VECTORs.
    /// If AllowUndef is true, then UNDEF elements will pass nullptr to Match.
    /// If AllowTypeMismatch is true then RetType + ArgTypes don't need to match.
    bool matchBinaryPredicate(
        SDValue LHS, SDValue RHS,
        std::function<bool(ConstantSDNode *, ConstantSDNode *)> Match,
        bool AllowUndefs = false, bool AllowTypeMismatch = false);
  
    /// Returns true if the specified value is the overflow result from one
    /// of the overflow intrinsic nodes.
    inline bool isOverflowIntrOpRes(SDValue Op) {
      unsigned Opc = Op.getOpcode();
      return (Op.getResNo() == 1 &&
              (Opc == ISD::SADDO || Opc == ISD::UADDO || Opc == ISD::SSUBO ||
               Opc == ISD::USUBO || Opc == ISD::SMULO || Opc == ISD::UMULO));
    }
  
  } // end namespace ISD
  
  } // end namespace llvm
  
  #endif // LLVM_CODEGEN_SELECTIONDAGNODES_H
  