text: //===-- llvm/InstrTypes.h - Important Instruction subclasses ----*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file defines various meta classes of instructions that exist in the VM
  // representation.  Specific concrete subclasses of these may be found in the
  // i*.h files...
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_IR_INSTRTYPES_H
  #define LLVM_IR_INSTRTYPES_H
  
  #include "llvm/ADT/Twine.h"
  #include "llvm/IR/DerivedTypes.h"
  #include "llvm/IR/Instruction.h"
  #include "llvm/IR/OperandTraits.h"
  
  namespace llvm {
  
  class LLVMContext;
  
  //===----------------------------------------------------------------------===//
  //                            TerminatorInst Class
  //===----------------------------------------------------------------------===//
  
  /// Subclasses of this class are all able to terminate a basic
  /// block. Thus, these are all the flow control type of operations.
  ///
  class TerminatorInst : public Instruction {
  protected:
    TerminatorInst(Type *Ty, Instruction::TermOps iType,
                   Use *Ops, unsigned NumOps,
                   Instruction *InsertBefore = nullptr)
      : Instruction(Ty, iType, Ops, NumOps, InsertBefore) {}
  
    TerminatorInst(Type *Ty, Instruction::TermOps iType,
                   Use *Ops, unsigned NumOps, BasicBlock *InsertAtEnd)
      : Instruction(Ty, iType, Ops, NumOps, InsertAtEnd) {}
  
    // Out of line virtual method, so the vtable, etc has a home.
    ~TerminatorInst() override;
  
    /// Virtual methods - Terminators should overload these and provide inline
    /// overrides of non-V methods.
    virtual BasicBlock *getSuccessorV(unsigned idx) const = 0;
    virtual unsigned getNumSuccessorsV() const = 0;
    virtual void setSuccessorV(unsigned idx, BasicBlock *B) = 0;
  public:
  
    /// Return the number of successors that this terminator has.
    unsigned getNumSuccessors() const {
      return getNumSuccessorsV();
    }
  
    /// Return the specified successor.
    BasicBlock *getSuccessor(unsigned idx) const {
      return getSuccessorV(idx);
    }
  
    /// Update the specified successor to point at the provided block.
    void setSuccessor(unsigned idx, BasicBlock *B) {
      setSuccessorV(idx, B);
    }
  
    // Methods for support type inquiry through isa, cast, and dyn_cast:
    static inline bool classof(const Instruction *I) {
      return I->isTerminator();
    }
    static inline bool classof(const Value *V) {
      return isa<Instruction>(V) && classof(cast<Instruction>(V));
    }
  };
  
  
  //===----------------------------------------------------------------------===//
  //                          UnaryInstruction Class
  //===----------------------------------------------------------------------===//
  
  class UnaryInstruction : public Instruction {
    void *operator new(size_t, unsigned) = delete;
  
  protected:
    UnaryInstruction(Type *Ty, unsigned iType, Value *V,
                     Instruction *IB = nullptr)
      : Instruction(Ty, iType, &Op<0>(), 1, IB) {
      Op<0>() = V;
    }
    UnaryInstruction(Type *Ty, unsigned iType, Value *V, BasicBlock *IAE)
      : Instruction(Ty, iType, &Op<0>(), 1, IAE) {
      Op<0>() = V;
    }
  public:
    // allocate space for exactly one operand
    void *operator new(size_t s) {
      return User::operator new(s, 1);
    }
  
    // Out of line virtual method, so the vtable, etc has a home.
    ~UnaryInstruction() override;
  
    /// Transparently provide more efficient getOperand methods.
    DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
  
    // Methods for support type inquiry through isa, cast, and dyn_cast:
    static inline bool classof(const Instruction *I) {
      return I->getOpcode() == Instruction::Alloca ||
             I->getOpcode() == Instruction::Load ||
             I->getOpcode() == Instruction::VAArg ||
             I->getOpcode() == Instruction::ExtractValue ||
             (I->getOpcode() >= CastOpsBegin && I->getOpcode() < CastOpsEnd);
    }
    static inline bool classof(const Value *V) {
      return isa<Instruction>(V) && classof(cast<Instruction>(V));
    }
  };
  
  template <>
  struct OperandTraits<UnaryInstruction> :
    public FixedNumOperandTraits<UnaryInstruction, 1> {
  };
  
  DEFINE_TRANSPARENT_OPERAND_ACCESSORS(UnaryInstruction, Value)
  
  //===----------------------------------------------------------------------===//
  //                           BinaryOperator Class
  //===----------------------------------------------------------------------===//
  
  class BinaryOperator : public Instruction {
    void *operator new(size_t, unsigned) = delete;
  protected:
    void init(BinaryOps iType);
    BinaryOperator(BinaryOps iType, Value *S1, Value *S2, Type *Ty,
                   const Twine &Name, Instruction *InsertBefore);
    BinaryOperator(BinaryOps iType, Value *S1, Value *S2, Type *Ty,
                   const Twine &Name, BasicBlock *InsertAtEnd);
  
    // Note: Instruction needs to be a friend here to call cloneImpl.
    friend class Instruction;
    BinaryOperator *cloneImpl() const;
  
  public:
    // allocate space for exactly two operands
    void *operator new(size_t s) {
      return User::operator new(s, 2);
    }
  
    /// Transparently provide more efficient getOperand methods.
    DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
  
    /// Construct a binary instruction, given the opcode and the two
    /// operands.  Optionally (if InstBefore is specified) insert the instruction
    /// into a BasicBlock right before the specified instruction.  The specified
    /// Instruction is allowed to be a dereferenced end iterator.
    ///
    static BinaryOperator *Create(BinaryOps Op, Value *S1, Value *S2,
                                  const Twine &Name = Twine(),
                                  Instruction *InsertBefore = nullptr);
  
    /// Construct a binary instruction, given the opcode and the two
    /// operands.  Also automatically insert this instruction to the end of the
    /// BasicBlock specified.
    ///
    static BinaryOperator *Create(BinaryOps Op, Value *S1, Value *S2,
                                  const Twine &Name, BasicBlock *InsertAtEnd);
  
    /// These methods just forward to Create, and are useful when you
    /// statically know what type of instruction you're going to create.  These
    /// helpers just save some typing.
  #define HANDLE_BINARY_INST(N, OPC, CLASS) \
    static BinaryOperator *Create##OPC(Value *V1, Value *V2, \
                                       const Twine &Name = "") {\
      return Create(Instruction::OPC, V1, V2, Name);\
    }
  #include "llvm/IR/Instruction.def"
  #define HANDLE_BINARY_INST(N, OPC, CLASS) \
    static BinaryOperator *Create##OPC(Value *V1, Value *V2, \
                                       const Twine &Name, BasicBlock *BB) {\
      return Create(Instruction::OPC, V1, V2, Name, BB);\
    }
  #include "llvm/IR/Instruction.def"
  #define HANDLE_BINARY_INST(N, OPC, CLASS) \
    static BinaryOperator *Create##OPC(Value *V1, Value *V2, \
                                       const Twine &Name, Instruction *I) {\
      return Create(Instruction::OPC, V1, V2, Name, I);\
    }
  #include "llvm/IR/Instruction.def"
  
    static BinaryOperator *CreateNSW(BinaryOps Opc, Value *V1, Value *V2,
                                     const Twine &Name = "") {
      BinaryOperator *BO = Create(Opc, V1, V2, Name);
      BO->setHasNoSignedWrap(true);
      return BO;
    }
    static BinaryOperator *CreateNSW(BinaryOps Opc, Value *V1, Value *V2,
                                     const Twine &Name, BasicBlock *BB) {
      BinaryOperator *BO = Create(Opc, V1, V2, Name, BB);
      BO->setHasNoSignedWrap(true);
      return BO;
    }
    static BinaryOperator *CreateNSW(BinaryOps Opc, Value *V1, Value *V2,
                                     const Twine &Name, Instruction *I) {
      BinaryOperator *BO = Create(Opc, V1, V2, Name, I);
      BO->setHasNoSignedWrap(true);
      return BO;
    }
    
    static BinaryOperator *CreateNUW(BinaryOps Opc, Value *V1, Value *V2,
                                     const Twine &Name = "") {
      BinaryOperator *BO = Create(Opc, V1, V2, Name);
      BO->setHasNoUnsignedWrap(true);
      return BO;
    }
    static BinaryOperator *CreateNUW(BinaryOps Opc, Value *V1, Value *V2,
                                     const Twine &Name, BasicBlock *BB) {
      BinaryOperator *BO = Create(Opc, V1, V2, Name, BB);
      BO->setHasNoUnsignedWrap(true);
      return BO;
    }
    static BinaryOperator *CreateNUW(BinaryOps Opc, Value *V1, Value *V2,
                                     const Twine &Name, Instruction *I) {
      BinaryOperator *BO = Create(Opc, V1, V2, Name, I);
      BO->setHasNoUnsignedWrap(true);
      return BO;
    }
    
    static BinaryOperator *CreateExact(BinaryOps Opc, Value *V1, Value *V2,
                                       const Twine &Name = "") {
      BinaryOperator *BO = Create(Opc, V1, V2, Name);
      BO->setIsExact(true);
      return BO;
    }
    static BinaryOperator *CreateExact(BinaryOps Opc, Value *V1, Value *V2,
                                       const Twine &Name, BasicBlock *BB) {
      BinaryOperator *BO = Create(Opc, V1, V2, Name, BB);
      BO->setIsExact(true);
      return BO;
    }
    static BinaryOperator *CreateExact(BinaryOps Opc, Value *V1, Value *V2,
                                       const Twine &Name, Instruction *I) {
      BinaryOperator *BO = Create(Opc, V1, V2, Name, I);
      BO->setIsExact(true);
      return BO;
    }
    
  #define DEFINE_HELPERS(OPC, NUWNSWEXACT)                                     \
    static BinaryOperator *Create ## NUWNSWEXACT ## OPC                        \
             (Value *V1, Value *V2, const Twine &Name = "") {                  \
      return Create ## NUWNSWEXACT(Instruction::OPC, V1, V2, Name);            \
    }                                                                          \
    static BinaryOperator *Create ## NUWNSWEXACT ## OPC                        \
             (Value *V1, Value *V2, const Twine &Name, BasicBlock *BB) {       \
      return Create ## NUWNSWEXACT(Instruction::OPC, V1, V2, Name, BB);        \
    }                                                                          \
    static BinaryOperator *Create ## NUWNSWEXACT ## OPC                        \
             (Value *V1, Value *V2, const Twine &Name, Instruction *I) {       \
      return Create ## NUWNSWEXACT(Instruction::OPC, V1, V2, Name, I);         \
    }
    
    DEFINE_HELPERS(Add, NSW)  // CreateNSWAdd
    DEFINE_HELPERS(Add, NUW)  // CreateNUWAdd
    DEFINE_HELPERS(Sub, NSW)  // CreateNSWSub
    DEFINE_HELPERS(Sub, NUW)  // CreateNUWSub
    DEFINE_HELPERS(Mul, NSW)  // CreateNSWMul
    DEFINE_HELPERS(Mul, NUW)  // CreateNUWMul
    DEFINE_HELPERS(Shl, NSW)  // CreateNSWShl
    DEFINE_HELPERS(Shl, NUW)  // CreateNUWShl
  
    DEFINE_HELPERS(SDiv, Exact)  // CreateExactSDiv
    DEFINE_HELPERS(UDiv, Exact)  // CreateExactUDiv
    DEFINE_HELPERS(AShr, Exact)  // CreateExactAShr
    DEFINE_HELPERS(LShr, Exact)  // CreateExactLShr
  
  #undef DEFINE_HELPERS
    
    /// Helper functions to construct and inspect unary operations (NEG and NOT)
    /// via binary operators SUB and XOR:
    ///
    /// Create the NEG and NOT instructions out of SUB and XOR instructions.
    ///
    static BinaryOperator *CreateNeg(Value *Op, const Twine &Name = "",
                                     Instruction *InsertBefore = nullptr);
    static BinaryOperator *CreateNeg(Value *Op, const Twine &Name,
                                     BasicBlock *InsertAtEnd);
    static BinaryOperator *CreateNSWNeg(Value *Op, const Twine &Name = "",
                                        Instruction *InsertBefore = nullptr);
    static BinaryOperator *CreateNSWNeg(Value *Op, const Twine &Name,
                                        BasicBlock *InsertAtEnd);
    static BinaryOperator *CreateNUWNeg(Value *Op, const Twine &Name = "",
                                        Instruction *InsertBefore = nullptr);
    static BinaryOperator *CreateNUWNeg(Value *Op, const Twine &Name,
                                        BasicBlock *InsertAtEnd);
    static BinaryOperator *CreateFNeg(Value *Op, const Twine &Name = "",
                                      Instruction *InsertBefore = nullptr);
    static BinaryOperator *CreateFNeg(Value *Op, const Twine &Name,
                                      BasicBlock *InsertAtEnd);
    static BinaryOperator *CreateNot(Value *Op, const Twine &Name = "",
                                     Instruction *InsertBefore = nullptr);
    static BinaryOperator *CreateNot(Value *Op, const Twine &Name,
                                     BasicBlock *InsertAtEnd);
  
    /// Check if the given Value is a NEG, FNeg, or NOT instruction.
    ///
    static bool isNeg(const Value *V);
    static bool isFNeg(const Value *V, bool IgnoreZeroSign=false);
    static bool isNot(const Value *V);
  
    /// Helper functions to extract the unary argument of a NEG, FNEG or NOT
    /// operation implemented via Sub, FSub, or Xor.
    ///
    static const Value *getNegArgument(const Value *BinOp);
    static       Value *getNegArgument(      Value *BinOp);
    static const Value *getFNegArgument(const Value *BinOp);
    static       Value *getFNegArgument(      Value *BinOp);
    static const Value *getNotArgument(const Value *BinOp);
    static       Value *getNotArgument(      Value *BinOp);
  
    BinaryOps getOpcode() const {
      return static_cast<BinaryOps>(Instruction::getOpcode());
    }
  
    /// Exchange the two operands to this instruction.
    /// This instruction is safe to use on any binary instruction and
    /// does not modify the semantics of the instruction.  If the instruction
    /// cannot be reversed (ie, it's a Div), then return true.
    ///
    bool swapOperands();
  
    /// Set or clear the nsw flag on this instruction, which must be an operator
    /// which supports this flag. See LangRef.html for the meaning of this flag.
    void setHasNoUnsignedWrap(bool b = true);
  
    /// Set or clear the nsw flag on this instruction, which must be an operator
    /// which supports this flag. See LangRef.html for the meaning of this flag.
    void setHasNoSignedWrap(bool b = true);
  
    /// Set or clear the exact flag on this instruction, which must be an operator
    /// which supports this flag. See LangRef.html for the meaning of this flag.
    void setIsExact(bool b = true);
  
    /// Determine whether the no unsigned wrap flag is set.
    bool hasNoUnsignedWrap() const;
  
    /// Determine whether the no signed wrap flag is set.
    bool hasNoSignedWrap() const;
  
    /// Determine whether the exact flag is set.
    bool isExact() const;
  
    /// Convenience method to copy supported wrapping, exact, and fast-math flags
    /// from V to this instruction.
    void copyIRFlags(const Value *V);
    
    /// Logical 'and' of any supported wrapping, exact, and fast-math flags of
    /// V and this instruction.
    void andIRFlags(const Value *V);
  
    // Methods for support type inquiry through isa, cast, and dyn_cast:
    static inline bool classof(const Instruction *I) {
      return I->isBinaryOp();
    }
    static inline bool classof(const Value *V) {
      return isa<Instruction>(V) && classof(cast<Instruction>(V));
    }
  };
  
  template <>
  struct OperandTraits<BinaryOperator> :
    public FixedNumOperandTraits<BinaryOperator, 2> {
  };
  
  DEFINE_TRANSPARENT_OPERAND_ACCESSORS(BinaryOperator, Value)
  
  //===----------------------------------------------------------------------===//
  //                               CastInst Class
  //===----------------------------------------------------------------------===//
  
  /// This is the base class for all instructions that perform data
  /// casts. It is simply provided so that instruction category testing
  /// can be performed with code like:
  ///
  /// if (isa<CastInst>(Instr)) { ... }
  /// @brief Base class of casting instructions.
  class CastInst : public UnaryInstruction {
    void anchor() override;
  protected:
    /// @brief Constructor with insert-before-instruction semantics for subclasses
    CastInst(Type *Ty, unsigned iType, Value *S,
             const Twine &NameStr = "", Instruction *InsertBefore = nullptr)
      : UnaryInstruction(Ty, iType, S, InsertBefore) {
      setName(NameStr);
    }
    /// @brief Constructor with insert-at-end-of-block semantics for subclasses
    CastInst(Type *Ty, unsigned iType, Value *S,
             const Twine &NameStr, BasicBlock *InsertAtEnd)
      : UnaryInstruction(Ty, iType, S, InsertAtEnd) {
      setName(NameStr);
    }
  public:
    /// Provides a way to construct any of the CastInst subclasses using an
    /// opcode instead of the subclass's constructor. The opcode must be in the
    /// CastOps category (Instruction::isCast(opcode) returns true). This
    /// constructor has insert-before-instruction semantics to automatically
    /// insert the new CastInst before InsertBefore (if it is non-null).
    /// @brief Construct any of the CastInst subclasses
    static CastInst *Create(
      Instruction::CastOps,    ///< The opcode of the cast instruction
      Value *S,                ///< The value to be casted (operand 0)
      Type *Ty,          ///< The type to which cast should be made
      const Twine &Name = "", ///< Name for the instruction
      Instruction *InsertBefore = nullptr ///< Place to insert the instruction
    );
    /// Provides a way to construct any of the CastInst subclasses using an
    /// opcode instead of the subclass's constructor. The opcode must be in the
    /// CastOps category. This constructor has insert-at-end-of-block semantics
    /// to automatically insert the new CastInst at the end of InsertAtEnd (if
    /// its non-null).
    /// @brief Construct any of the CastInst subclasses
    static CastInst *Create(
      Instruction::CastOps,    ///< The opcode for the cast instruction
      Value *S,                ///< The value to be casted (operand 0)
      Type *Ty,          ///< The type to which operand is casted
      const Twine &Name, ///< The name for the instruction
      BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
    );
  
    /// @brief Create a ZExt or BitCast cast instruction
    static CastInst *CreateZExtOrBitCast(
      Value *S,                ///< The value to be casted (operand 0)
      Type *Ty,          ///< The type to which cast should be made
      const Twine &Name = "", ///< Name for the instruction
      Instruction *InsertBefore = nullptr ///< Place to insert the instruction
    );
  
    /// @brief Create a ZExt or BitCast cast instruction
    static CastInst *CreateZExtOrBitCast(
      Value *S,                ///< The value to be casted (operand 0)
      Type *Ty,          ///< The type to which operand is casted
      const Twine &Name, ///< The name for the instruction
      BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
    );
  
    /// @brief Create a SExt or BitCast cast instruction
    static CastInst *CreateSExtOrBitCast(
      Value *S,                ///< The value to be casted (operand 0)
      Type *Ty,          ///< The type to which cast should be made
      const Twine &Name = "", ///< Name for the instruction
      Instruction *InsertBefore = nullptr ///< Place to insert the instruction
    );
  
    /// @brief Create a SExt or BitCast cast instruction
    static CastInst *CreateSExtOrBitCast(
      Value *S,                ///< The value to be casted (operand 0)
      Type *Ty,          ///< The type to which operand is casted
      const Twine &Name, ///< The name for the instruction
      BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
    );
  
    /// @brief Create a BitCast AddrSpaceCast, or a PtrToInt cast instruction.
    static CastInst *CreatePointerCast(
      Value *S,                ///< The pointer value to be casted (operand 0)
      Type *Ty,          ///< The type to which operand is casted
      const Twine &Name, ///< The name for the instruction
      BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
    );
  
    /// @brief Create a BitCast, AddrSpaceCast or a PtrToInt cast instruction.
    static CastInst *CreatePointerCast(
      Value *S,                ///< The pointer value to be casted (operand 0)
      Type *Ty,          ///< The type to which cast should be made
      const Twine &Name = "", ///< Name for the instruction
      Instruction *InsertBefore = nullptr ///< Place to insert the instruction
    );
  
    /// @brief Create a BitCast or an AddrSpaceCast cast instruction.
    static CastInst *CreatePointerBitCastOrAddrSpaceCast(
      Value *S,                ///< The pointer value to be casted (operand 0)
      Type *Ty,          ///< The type to which operand is casted
      const Twine &Name, ///< The name for the instruction
      BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
    );
  
    /// @brief Create a BitCast or an AddrSpaceCast cast instruction.
    static CastInst *CreatePointerBitCastOrAddrSpaceCast(
      Value *S,                ///< The pointer value to be casted (operand 0)
      Type *Ty,          ///< The type to which cast should be made
      const Twine &Name = "", ///< Name for the instruction
      Instruction *InsertBefore = 0 ///< Place to insert the instruction
    );
  
    /// @brief Create a BitCast, a PtrToInt, or an IntToPTr cast instruction.
    ///
    /// If the value is a pointer type and the destination an integer type,
    /// creates a PtrToInt cast. If the value is an integer type and the
    /// destination a pointer type, creates an IntToPtr cast. Otherwise, creates
    /// a bitcast.
    static CastInst *CreateBitOrPointerCast(
      Value *S,                ///< The pointer value to be casted (operand 0)
      Type *Ty,          ///< The type to which cast should be made
      const Twine &Name = "", ///< Name for the instruction
      Instruction *InsertBefore = 0 ///< Place to insert the instruction
    );
  
    /// @brief Create a ZExt, BitCast, or Trunc for int -> int casts.
    static CastInst *CreateIntegerCast(
      Value *S,                ///< The pointer value to be casted (operand 0)
      Type *Ty,          ///< The type to which cast should be made
      bool isSigned,           ///< Whether to regard S as signed or not
      const Twine &Name = "", ///< Name for the instruction
      Instruction *InsertBefore = nullptr ///< Place to insert the instruction
    );
  
    /// @brief Create a ZExt, BitCast, or Trunc for int -> int casts.
    static CastInst *CreateIntegerCast(
      Value *S,                ///< The integer value to be casted (operand 0)
      Type *Ty,          ///< The integer type to which operand is casted
      bool isSigned,           ///< Whether to regard S as signed or not
      const Twine &Name, ///< The name for the instruction
      BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
    );
  
    /// @brief Create an FPExt, BitCast, or FPTrunc for fp -> fp casts
    static CastInst *CreateFPCast(
      Value *S,                ///< The floating point value to be casted
      Type *Ty,          ///< The floating point type to cast to
      const Twine &Name = "", ///< Name for the instruction
      Instruction *InsertBefore = nullptr ///< Place to insert the instruction
    );
  
    /// @brief Create an FPExt, BitCast, or FPTrunc for fp -> fp casts
    static CastInst *CreateFPCast(
      Value *S,                ///< The floating point value to be casted
      Type *Ty,          ///< The floating point type to cast to
      const Twine &Name, ///< The name for the instruction
      BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
    );
  
    /// @brief Create a Trunc or BitCast cast instruction
    static CastInst *CreateTruncOrBitCast(
      Value *S,                ///< The value to be casted (operand 0)
      Type *Ty,          ///< The type to which cast should be made
      const Twine &Name = "", ///< Name for the instruction
      Instruction *InsertBefore = nullptr ///< Place to insert the instruction
    );
  
    /// @brief Create a Trunc or BitCast cast instruction
    static CastInst *CreateTruncOrBitCast(
      Value *S,                ///< The value to be casted (operand 0)
      Type *Ty,          ///< The type to which operand is casted
      const Twine &Name, ///< The name for the instruction
      BasicBlock *InsertAtEnd  ///< The block to insert the instruction into
    );
  
    /// @brief Check whether it is valid to call getCastOpcode for these types.
    static bool isCastable(
      Type *SrcTy, ///< The Type from which the value should be cast.
      Type *DestTy ///< The Type to which the value should be cast.
    );
  
    /// @brief Check whether a bitcast between these types is valid
    static bool isBitCastable(
      Type *SrcTy, ///< The Type from which the value should be cast.
      Type *DestTy ///< The Type to which the value should be cast.
    );
  
    /// @brief Check whether a bitcast, inttoptr, or ptrtoint cast between these
    /// types is valid and a no-op.
    ///
    /// This ensures that any pointer<->integer cast has enough bits in the
    /// integer and any other cast is a bitcast.
    static bool isBitOrNoopPointerCastable(
        Type *SrcTy,  ///< The Type from which the value should be cast.
        Type *DestTy, ///< The Type to which the value should be cast.
        const DataLayout &DL);
  
    /// Returns the opcode necessary to cast Val into Ty using usual casting
    /// rules.
    /// @brief Infer the opcode for cast operand and type
    static Instruction::CastOps getCastOpcode(
      const Value *Val, ///< The value to cast
      bool SrcIsSigned, ///< Whether to treat the source as signed
      Type *Ty,   ///< The Type to which the value should be casted
      bool DstIsSigned  ///< Whether to treate the dest. as signed
    );
  
    /// There are several places where we need to know if a cast instruction
    /// only deals with integer source and destination types. To simplify that
    /// logic, this method is provided.
    /// @returns true iff the cast has only integral typed operand and dest type.
    /// @brief Determine if this is an integer-only cast.
    bool isIntegerCast() const;
  
    /// A lossless cast is one that does not alter the basic value. It implies
    /// a no-op cast but is more stringent, preventing things like int->float,
    /// long->double, or int->ptr.
    /// @returns true iff the cast is lossless.
    /// @brief Determine if this is a lossless cast.
    bool isLosslessCast() const;
  
    /// A no-op cast is one that can be effected without changing any bits.
    /// It implies that the source and destination types are the same size. The
    /// IntPtrTy argument is used to make accurate determinations for casts
    /// involving Integer and Pointer types. They are no-op casts if the integer
    /// is the same size as the pointer. However, pointer size varies with
    /// platform. Generally, the result of DataLayout::getIntPtrType() should be
    /// passed in. If that's not available, use Type::Int64Ty, which will make
    /// the isNoopCast call conservative.
    /// @brief Determine if the described cast is a no-op cast.
    static bool isNoopCast(
      Instruction::CastOps Opcode,  ///< Opcode of cast
      Type *SrcTy,   ///< SrcTy of cast
      Type *DstTy,   ///< DstTy of cast
      Type *IntPtrTy ///< Integer type corresponding to Ptr types
    );
  
    /// @brief Determine if this cast is a no-op cast.
    bool isNoopCast(
      Type *IntPtrTy ///< Integer type corresponding to pointer
    ) const;
  
    /// @brief Determine if this cast is a no-op cast.
    ///
    /// \param DL is the DataLayout to get the Int Ptr type from.
    bool isNoopCast(const DataLayout &DL) const;
  
    /// Determine how a pair of casts can be eliminated, if they can be at all.
    /// This is a helper function for both CastInst and ConstantExpr.
    /// @returns 0 if the CastInst pair can't be eliminated, otherwise
    /// returns Instruction::CastOps value for a cast that can replace
    /// the pair, casting SrcTy to DstTy.
    /// @brief Determine if a cast pair is eliminable
    static unsigned isEliminableCastPair(
      Instruction::CastOps firstOpcode,  ///< Opcode of first cast
      Instruction::CastOps secondOpcode, ///< Opcode of second cast
      Type *SrcTy, ///< SrcTy of 1st cast
      Type *MidTy, ///< DstTy of 1st cast & SrcTy of 2nd cast
      Type *DstTy, ///< DstTy of 2nd cast
      Type *SrcIntPtrTy, ///< Integer type corresponding to Ptr SrcTy, or null
      Type *MidIntPtrTy, ///< Integer type corresponding to Ptr MidTy, or null
      Type *DstIntPtrTy  ///< Integer type corresponding to Ptr DstTy, or null
    );
  
    /// @brief Return the opcode of this CastInst
    Instruction::CastOps getOpcode() const {
      return Instruction::CastOps(Instruction::getOpcode());
    }
  
    /// @brief Return the source type, as a convenience
    Type* getSrcTy() const { return getOperand(0)->getType(); }
    /// @brief Return the destination type, as a convenience
    Type* getDestTy() const { return getType(); }
  
    /// This method can be used to determine if a cast from S to DstTy using
    /// Opcode op is valid or not.
    /// @returns true iff the proposed cast is valid.
    /// @brief Determine if a cast is valid without creating one.
    static bool castIsValid(Instruction::CastOps op, Value *S, Type *DstTy);
  
    /// @brief Methods for support type inquiry through isa, cast, and dyn_cast:
    static inline bool classof(const Instruction *I) {
      return I->isCast();
    }
    static inline bool classof(const Value *V) {
      return isa<Instruction>(V) && classof(cast<Instruction>(V));
    }
  };
  
  //===----------------------------------------------------------------------===//
  //                               CmpInst Class
  //===----------------------------------------------------------------------===//
  
  /// This class is the base class for the comparison instructions.
  /// @brief Abstract base class of comparison instructions.
  class CmpInst : public Instruction {
    void *operator new(size_t, unsigned) = delete;
    CmpInst() = delete;
  protected:
    CmpInst(Type *ty, Instruction::OtherOps op, unsigned short pred,
            Value *LHS, Value *RHS, const Twine &Name = "",
            Instruction *InsertBefore = nullptr);
  
    CmpInst(Type *ty, Instruction::OtherOps op, unsigned short pred,
            Value *LHS, Value *RHS, const Twine &Name,
            BasicBlock *InsertAtEnd);
  
    void anchor() override; // Out of line virtual method.
  public:
    /// This enumeration lists the possible predicates for CmpInst subclasses.
    /// Values in the range 0-31 are reserved for FCmpInst, while values in the
    /// range 32-64 are reserved for ICmpInst. This is necessary to ensure the
    /// predicate values are not overlapping between the classes.
    enum Predicate {
      // Opcode              U L G E    Intuitive operation
      FCMP_FALSE =  0,  ///< 0 0 0 0    Always false (always folded)
      FCMP_OEQ   =  1,  ///< 0 0 0 1    True if ordered and equal
      FCMP_OGT   =  2,  ///< 0 0 1 0    True if ordered and greater than
      FCMP_OGE   =  3,  ///< 0 0 1 1    True if ordered and greater than or equal
      FCMP_OLT   =  4,  ///< 0 1 0 0    True if ordered and less than
      FCMP_OLE   =  5,  ///< 0 1 0 1    True if ordered and less than or equal
      FCMP_ONE   =  6,  ///< 0 1 1 0    True if ordered and operands are unequal
      FCMP_ORD   =  7,  ///< 0 1 1 1    True if ordered (no nans)
      FCMP_UNO   =  8,  ///< 1 0 0 0    True if unordered: isnan(X) | isnan(Y)
      FCMP_UEQ   =  9,  ///< 1 0 0 1    True if unordered or equal
      FCMP_UGT   = 10,  ///< 1 0 1 0    True if unordered or greater than
      FCMP_UGE   = 11,  ///< 1 0 1 1    True if unordered, greater than, or equal
      FCMP_ULT   = 12,  ///< 1 1 0 0    True if unordered or less than
      FCMP_ULE   = 13,  ///< 1 1 0 1    True if unordered, less than, or equal
      FCMP_UNE   = 14,  ///< 1 1 1 0    True if unordered or not equal
      FCMP_TRUE  = 15,  ///< 1 1 1 1    Always true (always folded)
      FIRST_FCMP_PREDICATE = FCMP_FALSE,
      LAST_FCMP_PREDICATE = FCMP_TRUE,
      BAD_FCMP_PREDICATE = FCMP_TRUE + 1,
      ICMP_EQ    = 32,  ///< equal
      ICMP_NE    = 33,  ///< not equal
      ICMP_UGT   = 34,  ///< unsigned greater than
      ICMP_UGE   = 35,  ///< unsigned greater or equal
      ICMP_ULT   = 36,  ///< unsigned less than
      ICMP_ULE   = 37,  ///< unsigned less or equal
      ICMP_SGT   = 38,  ///< signed greater than
      ICMP_SGE   = 39,  ///< signed greater or equal
      ICMP_SLT   = 40,  ///< signed less than
      ICMP_SLE   = 41,  ///< signed less or equal
      FIRST_ICMP_PREDICATE = ICMP_EQ,
      LAST_ICMP_PREDICATE = ICMP_SLE,
      BAD_ICMP_PREDICATE = ICMP_SLE + 1
    };
  
    // allocate space for exactly two operands
    void *operator new(size_t s) {
      return User::operator new(s, 2);
    }
    /// Construct a compare instruction, given the opcode, the predicate and
    /// the two operands.  Optionally (if InstBefore is specified) insert the
    /// instruction into a BasicBlock right before the specified instruction.
    /// The specified Instruction is allowed to be a dereferenced end iterator.
    /// @brief Create a CmpInst
    static CmpInst *Create(OtherOps Op,
                           unsigned short predicate, Value *S1,
                           Value *S2, const Twine &Name = "",
                           Instruction *InsertBefore = nullptr);
  
    /// Construct a compare instruction, given the opcode, the predicate and the
    /// two operands.  Also automatically insert this instruction to the end of
    /// the BasicBlock specified.
    /// @brief Create a CmpInst
    static CmpInst *Create(OtherOps Op, unsigned short predicate, Value *S1,
                           Value *S2, const Twine &Name, BasicBlock *InsertAtEnd);
  
    /// @brief Get the opcode casted to the right type
    OtherOps getOpcode() const {
      return static_cast<OtherOps>(Instruction::getOpcode());
    }
  
    /// @brief Return the predicate for this instruction.
    Predicate getPredicate() const {
      return Predicate(getSubclassDataFromInstruction());
    }
  
    /// @brief Set the predicate for this instruction to the specified value.
    void setPredicate(Predicate P) { setInstructionSubclassData(P); }
  
    static bool isFPPredicate(Predicate P) {
      return P >= FIRST_FCMP_PREDICATE && P <= LAST_FCMP_PREDICATE;
    }
  
    static bool isIntPredicate(Predicate P) {
      return P >= FIRST_ICMP_PREDICATE && P <= LAST_ICMP_PREDICATE;
    }
  
    bool isFPPredicate() const { return isFPPredicate(getPredicate()); }
    bool isIntPredicate() const { return isIntPredicate(getPredicate()); }
  
  
    /// For example, EQ -> NE, UGT -> ULE, SLT -> SGE,
    ///              OEQ -> UNE, UGT -> OLE, OLT -> UGE, etc.
    /// @returns the inverse predicate for the instruction's current predicate.
    /// @brief Return the inverse of the instruction's predicate.
    Predicate getInversePredicate() const {
      return getInversePredicate(getPredicate());
    }
  
    /// For example, EQ -> NE, UGT -> ULE, SLT -> SGE,
    ///              OEQ -> UNE, UGT -> OLE, OLT -> UGE, etc.
    /// @returns the inverse predicate for predicate provided in \p pred.
    /// @brief Return the inverse of a given predicate
    static Predicate getInversePredicate(Predicate pred);
  
    /// For example, EQ->EQ, SLE->SGE, ULT->UGT,
    ///              OEQ->OEQ, ULE->UGE, OLT->OGT, etc.
    /// @returns the predicate that would be the result of exchanging the two
    /// operands of the CmpInst instruction without changing the result
    /// produced.
    /// @brief Return the predicate as if the operands were swapped
    Predicate getSwappedPredicate() const {
      return getSwappedPredicate(getPredicate());
    }
  
    /// This is a static version that you can use without an instruction
    /// available.
    /// @brief Return the predicate as if the operands were swapped.
    static Predicate getSwappedPredicate(Predicate pred);
  
    /// @brief Provide more efficient getOperand methods.
    DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
  
    /// This is just a convenience that dispatches to the subclasses.
    /// @brief Swap the operands and adjust predicate accordingly to retain
    /// the same comparison.
    void swapOperands();
  
    /// This is just a convenience that dispatches to the subclasses.
    /// @brief Determine if this CmpInst is commutative.
    bool isCommutative() const;
  
    /// This is just a convenience that dispatches to the subclasses.
    /// @brief Determine if this is an equals/not equals predicate.
    bool isEquality() const;
  
    /// @returns true if the comparison is signed, false otherwise.
    /// @brief Determine if this instruction is using a signed comparison.
    bool isSigned() const {
      return isSigned(getPredicate());
    }
  
    /// @returns true if the comparison is unsigned, false otherwise.
    /// @brief Determine if this instruction is using an unsigned comparison.
    bool isUnsigned() const {
      return isUnsigned(getPredicate());
    }
  
    /// This is just a convenience.
    /// @brief Determine if this is true when both operands are the same.
    bool isTrueWhenEqual() const {
      return isTrueWhenEqual(getPredicate());
    }
  
    /// This is just a convenience.
    /// @brief Determine if this is false when both operands are the same.
    bool isFalseWhenEqual() const {
      return isFalseWhenEqual(getPredicate());
    }
  
    /// @returns true if the predicate is unsigned, false otherwise.
    /// @brief Determine if the predicate is an unsigned operation.
    static bool isUnsigned(unsigned short predicate);
  
    /// @returns true if the predicate is signed, false otherwise.
    /// @brief Determine if the predicate is an signed operation.
    static bool isSigned(unsigned short predicate);
  
    /// @brief Determine if the predicate is an ordered operation.
    static bool isOrdered(unsigned short predicate);
  
    /// @brief Determine if the predicate is an unordered operation.
    static bool isUnordered(unsigned short predicate);
  
    /// Determine if the predicate is true when comparing a value with itself.
    static bool isTrueWhenEqual(unsigned short predicate);
  
    /// Determine if the predicate is false when comparing a value with itself.
    static bool isFalseWhenEqual(unsigned short predicate);
  
    /// @brief Methods for support type inquiry through isa, cast, and dyn_cast:
    static inline bool classof(const Instruction *I) {
      return I->getOpcode() == Instruction::ICmp ||
             I->getOpcode() == Instruction::FCmp;
    }
    static inline bool classof(const Value *V) {
      return isa<Instruction>(V) && classof(cast<Instruction>(V));
    }
  
    /// @brief Create a result type for fcmp/icmp
    static Type* makeCmpResultType(Type* opnd_type) {
      if (VectorType* vt = dyn_cast<VectorType>(opnd_type)) {
        return VectorType::get(Type::getInt1Ty(opnd_type->getContext()),
                               vt->getNumElements());
      }
      return Type::getInt1Ty(opnd_type->getContext());
    }
  private:
    // Shadow Value::setValueSubclassData with a private forwarding method so that
    // subclasses cannot accidentally use it.
    void setValueSubclassData(unsigned short D) {
      Value::setValueSubclassData(D);
    }
  };
  
  
  // FIXME: these are redundant if CmpInst < BinaryOperator
  template <>
  struct OperandTraits<CmpInst> : public FixedNumOperandTraits<CmpInst, 2> {
  };
  
  DEFINE_TRANSPARENT_OPERAND_ACCESSORS(CmpInst, Value)
  
  } // End llvm namespace
  
  #endif
  