text: //===- llvm/DerivedTypes.h - Classes for handling data types ----*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file contains the declarations of classes that represent "derived
  // types".  These are things like "arrays of x" or "structure of x, y, z" or
  // "function returning x taking (y,z) as parameters", etc...
  //
  // The implementations of these classes live in the Type.cpp file.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_IR_DERIVEDTYPES_H
  #define LLVM_IR_DERIVEDTYPES_H
  
  #include "llvh/ADT/ArrayRef.h"
  #include "llvh/ADT/STLExtras.h"
  #include "llvh/ADT/StringRef.h"
  #include "llvh/IR/Type.h"
  #include "llvh/Support/Casting.h"
  #include "llvh/Support/Compiler.h"
  #include <cassert>
  #include <cstdint>
  
  namespace llvh {
  
  class Value;
  class APInt;
  class LLVMContext;
  
  /// Class to represent integer types. Note that this class is also used to
  /// represent the built-in integer types: Int1Ty, Int8Ty, Int16Ty, Int32Ty and
  /// Int64Ty.
  /// Integer representation type
  class IntegerType : public Type {
    friend class LLVMContextImpl;
  
  protected:
    explicit IntegerType(LLVMContext &C, unsigned NumBits) : Type(C, IntegerTyID){
      setSubclassData(NumBits);
    }
  
  public:
    /// This enum is just used to hold constants we need for IntegerType.
    enum {
      MIN_INT_BITS = 1,        ///< Minimum number of bits that can be specified
      MAX_INT_BITS = (1<<24)-1 ///< Maximum number of bits that can be specified
        ///< Note that bit width is stored in the Type classes SubclassData field
        ///< which has 24 bits. This yields a maximum bit width of 16,777,215
        ///< bits.
    };
  
    /// This static method is the primary way of constructing an IntegerType.
    /// If an IntegerType with the same NumBits value was previously instantiated,
    /// that instance will be returned. Otherwise a new one will be created. Only
    /// one instance with a given NumBits value is ever created.
    /// Get or create an IntegerType instance.
    static IntegerType *get(LLVMContext &C, unsigned NumBits);
  
    /// Get the number of bits in this IntegerType
    unsigned getBitWidth() const { return getSubclassData(); }
  
    /// Return a bitmask with ones set for all of the bits that can be set by an
    /// unsigned version of this type. This is 0xFF for i8, 0xFFFF for i16, etc.
    uint64_t getBitMask() const {
      return ~uint64_t(0UL) >> (64-getBitWidth());
    }
  
    /// Return a uint64_t with just the most significant bit set (the sign bit, if
    /// the value is treated as a signed number).
    uint64_t getSignBit() const {
      return 1ULL << (getBitWidth()-1);
    }
  
    /// For example, this is 0xFF for an 8 bit integer, 0xFFFF for i16, etc.
    /// @returns a bit mask with ones set for all the bits of this type.
    /// Get a bit mask for this type.
    APInt getMask() const;
  
    /// This method determines if the width of this IntegerType is a power-of-2
    /// in terms of 8 bit bytes.
    /// @returns true if this is a power-of-2 byte width.
    /// Is this a power-of-2 byte-width IntegerType ?
    bool isPowerOf2ByteWidth() const;
  
    /// Methods for support type inquiry through isa, cast, and dyn_cast.
    static bool classof(const Type *T) {
      return T->getTypeID() == IntegerTyID;
    }
  };
  
  unsigned Type::getIntegerBitWidth() const {
    return cast<IntegerType>(this)->getBitWidth();
  }
  
  /// Class to represent function types
  ///
  class FunctionType : public Type {
    FunctionType(Type *Result, ArrayRef<Type*> Params, bool IsVarArgs);
  
  public:
    FunctionType(const FunctionType &) = delete;
    FunctionType &operator=(const FunctionType &) = delete;
  
    /// This static method is the primary way of constructing a FunctionType.
    static FunctionType *get(Type *Result,
                             ArrayRef<Type*> Params, bool isVarArg);
  
    /// Create a FunctionType taking no parameters.
    static FunctionType *get(Type *Result, bool isVarArg);
  
    /// Return true if the specified type is valid as a return type.
    static bool isValidReturnType(Type *RetTy);
  
    /// Return true if the specified type is valid as an argument type.
    static bool isValidArgumentType(Type *ArgTy);
  
    bool isVarArg() const { return getSubclassData()!=0; }
    Type *getReturnType() const { return ContainedTys[0]; }
  
    using param_iterator = Type::subtype_iterator;
  
    param_iterator param_begin() const { return ContainedTys + 1; }
    param_iterator param_end() const { return &ContainedTys[NumContainedTys]; }
    ArrayRef<Type *> params() const {
      return makeArrayRef(param_begin(), param_end());
    }
  
    /// Parameter type accessors.
    Type *getParamType(unsigned i) const { return ContainedTys[i+1]; }
  
    /// Return the number of fixed parameters this function type requires.
    /// This does not consider varargs.
    unsigned getNumParams() const { return NumContainedTys - 1; }
  
    /// Methods for support type inquiry through isa, cast, and dyn_cast.
    static bool classof(const Type *T) {
      return T->getTypeID() == FunctionTyID;
    }
  };
  static_assert(alignof(FunctionType) >= alignof(Type *),
                "Alignment sufficient for objects appended to FunctionType");
  
  bool Type::isFunctionVarArg() const {
    return cast<FunctionType>(this)->isVarArg();
  }
  
  Type *Type::getFunctionParamType(unsigned i) const {
    return cast<FunctionType>(this)->getParamType(i);
  }
  
  unsigned Type::getFunctionNumParams() const {
    return cast<FunctionType>(this)->getNumParams();
  }
  
  /// Common super class of ArrayType, StructType and VectorType.
  class CompositeType : public Type {
  protected:
    explicit CompositeType(LLVMContext &C, TypeID tid) : Type(C, tid) {}
  
  public:
    /// Given an index value into the type, return the type of the element.
    Type *getTypeAtIndex(const Value *V) const;
    Type *getTypeAtIndex(unsigned Idx) const;
    bool indexValid(const Value *V) const;
    bool indexValid(unsigned Idx) const;
  
    /// Methods for support type inquiry through isa, cast, and dyn_cast.
    static bool classof(const Type *T) {
      return T->getTypeID() == ArrayTyID ||
             T->getTypeID() == StructTyID ||
             T->getTypeID() == VectorTyID;
    }
  };
  
  /// Class to represent struct types. There are two different kinds of struct
  /// types: Literal structs and Identified structs.
  ///
  /// Literal struct types (e.g. { i32, i32 }) are uniqued structurally, and must
  /// always have a body when created.  You can get one of these by using one of
  /// the StructType::get() forms.
  ///
  /// Identified structs (e.g. %foo or %42) may optionally have a name and are not
  /// uniqued.  The names for identified structs are managed at the LLVMContext
  /// level, so there can only be a single identified struct with a given name in
  /// a particular LLVMContext.  Identified structs may also optionally be opaque
  /// (have no body specified).  You get one of these by using one of the
  /// StructType::create() forms.
  ///
  /// Independent of what kind of struct you have, the body of a struct type are
  /// laid out in memory consecutively with the elements directly one after the
  /// other (if the struct is packed) or (if not packed) with padding between the
  /// elements as defined by DataLayout (which is required to match what the code
  /// generator for a target expects).
  ///
  class StructType : public CompositeType {
    StructType(LLVMContext &C) : CompositeType(C, StructTyID) {}
  
    enum {
      /// This is the contents of the SubClassData field.
      SCDB_HasBody = 1,
      SCDB_Packed = 2,
      SCDB_IsLiteral = 4,
      SCDB_IsSized = 8
    };
  
    /// For a named struct that actually has a name, this is a pointer to the
    /// symbol table entry (maintained by LLVMContext) for the struct.
    /// This is null if the type is an literal struct or if it is a identified
    /// type that has an empty name.
    void *SymbolTableEntry = nullptr;
  
  public:
    StructType(const StructType &) = delete;
    StructType &operator=(const StructType &) = delete;
  
    /// This creates an identified struct.
    static StructType *create(LLVMContext &Context, StringRef Name);
    static StructType *create(LLVMContext &Context);
  
    static StructType *create(ArrayRef<Type *> Elements, StringRef Name,
                              bool isPacked = false);
    static StructType *create(ArrayRef<Type *> Elements);
    static StructType *create(LLVMContext &Context, ArrayRef<Type *> Elements,
                              StringRef Name, bool isPacked = false);
    static StructType *create(LLVMContext &Context, ArrayRef<Type *> Elements);
    template <class... Tys>
    static typename std::enable_if<are_base_of<Type, Tys...>::value,
                                   StructType *>::type
    create(StringRef Name, Type *elt1, Tys *... elts) {
      assert(elt1 && "Cannot create a struct type with no elements with this");
      SmallVector<llvh::Type *, 8> StructFields({elt1, elts...});
      return create(StructFields, Name);
    }
  
    /// This static method is the primary way to create a literal StructType.
    static StructType *get(LLVMContext &Context, ArrayRef<Type*> Elements,
                           bool isPacked = false);
  
    /// Create an empty structure type.
    static StructType *get(LLVMContext &Context, bool isPacked = false);
  
    /// This static method is a convenience method for creating structure types by
    /// specifying the elements as arguments. Note that this method always returns
    /// a non-packed struct, and requires at least one element type.
    template <class... Tys>
    static typename std::enable_if<are_base_of<Type, Tys...>::value,
                                   StructType *>::type
    get(Type *elt1, Tys *... elts) {
      assert(elt1 && "Cannot create a struct type with no elements with this");
      LLVMContext &Ctx = elt1->getContext();
      SmallVector<llvh::Type *, 8> StructFields({elt1, elts...});
      return llvh::StructType::get(Ctx, StructFields);
    }
  
    bool isPacked() const { return (getSubclassData() & SCDB_Packed) != 0; }
  
    /// Return true if this type is uniqued by structural equivalence, false if it
    /// is a struct definition.
    bool isLiteral() const { return (getSubclassData() & SCDB_IsLiteral) != 0; }
  
    /// Return true if this is a type with an identity that has no body specified
    /// yet. These prints as 'opaque' in .ll files.
    bool isOpaque() const { return (getSubclassData() & SCDB_HasBody) == 0; }
  
    /// isSized - Return true if this is a sized type.
    bool isSized(SmallPtrSetImpl<Type *> *Visited = nullptr) const;
  
    /// Return true if this is a named struct that has a non-empty name.
    bool hasName() const { return SymbolTableEntry != nullptr; }
  
    /// Return the name for this struct type if it has an identity.
    /// This may return an empty string for an unnamed struct type.  Do not call
    /// this on an literal type.
    StringRef getName() const;
  
    /// Change the name of this type to the specified name, or to a name with a
    /// suffix if there is a collision. Do not call this on an literal type.
    void setName(StringRef Name);
  
    /// Specify a body for an opaque identified type.
    void setBody(ArrayRef<Type*> Elements, bool isPacked = false);
  
    template <typename... Tys>
    typename std::enable_if<are_base_of<Type, Tys...>::value, void>::type
    setBody(Type *elt1, Tys *... elts) {
      assert(elt1 && "Cannot create a struct type with no elements with this");
      SmallVector<llvh::Type *, 8> StructFields({elt1, elts...});
      setBody(StructFields);
    }
  
    /// Return true if the specified type is valid as a element type.
    static bool isValidElementType(Type *ElemTy);
  
    // Iterator access to the elements.
    using element_iterator = Type::subtype_iterator;
  
    element_iterator element_begin() const { return ContainedTys; }
    element_iterator element_end() const { return &ContainedTys[NumContainedTys];}
    ArrayRef<Type *> const elements() const {
      return makeArrayRef(element_begin(), element_end());
    }
  
    /// Return true if this is layout identical to the specified struct.
    bool isLayoutIdentical(StructType *Other) const;
  
    /// Random access to the elements
    unsigned getNumElements() const { return NumContainedTys; }
    Type *getElementType(unsigned N) const {
      assert(N < NumContainedTys && "Element number out of range!");
      return ContainedTys[N];
    }
  
    /// Methods for support type inquiry through isa, cast, and dyn_cast.
    static bool classof(const Type *T) {
      return T->getTypeID() == StructTyID;
    }
  };
  
  StringRef Type::getStructName() const {
    return cast<StructType>(this)->getName();
  }
  
  unsigned Type::getStructNumElements() const {
    return cast<StructType>(this)->getNumElements();
  }
  
  Type *Type::getStructElementType(unsigned N) const {
    return cast<StructType>(this)->getElementType(N);
  }
  
  /// This is the superclass of the array and vector type classes. Both of these
  /// represent "arrays" in memory. The array type represents a specifically sized
  /// array, and the vector type represents a specifically sized array that allows
  /// for use of SIMD instructions. SequentialType holds the common features of
  /// both, which stem from the fact that both lay their components out in memory
  /// identically.
  class SequentialType : public CompositeType {
    Type *ContainedType;               ///< Storage for the single contained type.
    uint64_t NumElements;
  
  protected:
    SequentialType(TypeID TID, Type *ElType, uint64_t NumElements)
      : CompositeType(ElType->getContext(), TID), ContainedType(ElType),
        NumElements(NumElements) {
      ContainedTys = &ContainedType;
      NumContainedTys = 1;
    }
  
  public:
    SequentialType(const SequentialType &) = delete;
    SequentialType &operator=(const SequentialType &) = delete;
  
    uint64_t getNumElements() const { return NumElements; }
    Type *getElementType() const { return ContainedType; }
  
    /// Methods for support type inquiry through isa, cast, and dyn_cast.
    static bool classof(const Type *T) {
      return T->getTypeID() == ArrayTyID || T->getTypeID() == VectorTyID;
    }
  };
  
  /// Class to represent array types.
  class ArrayType : public SequentialType {
    ArrayType(Type *ElType, uint64_t NumEl);
  
  public:
    ArrayType(const ArrayType &) = delete;
    ArrayType &operator=(const ArrayType &) = delete;
  
    /// This static method is the primary way to construct an ArrayType
    static ArrayType *get(Type *ElementType, uint64_t NumElements);
  
    /// Return true if the specified type is valid as a element type.
    static bool isValidElementType(Type *ElemTy);
  
    /// Methods for support type inquiry through isa, cast, and dyn_cast.
    static bool classof(const Type *T) {
      return T->getTypeID() == ArrayTyID;
    }
  };
  
  uint64_t Type::getArrayNumElements() const {
    return cast<ArrayType>(this)->getNumElements();
  }
  
  /// Class to represent vector types.
  class VectorType : public SequentialType {
    VectorType(Type *ElType, unsigned NumEl);
  
  public:
    VectorType(const VectorType &) = delete;
    VectorType &operator=(const VectorType &) = delete;
  
    /// This static method is the primary way to construct an VectorType.
    static VectorType *get(Type *ElementType, unsigned NumElements);
  
    /// This static method gets a VectorType with the same number of elements as
    /// the input type, and the element type is an integer type of the same width
    /// as the input element type.
    static VectorType *getInteger(VectorType *VTy) {
      unsigned EltBits = VTy->getElementType()->getPrimitiveSizeInBits();
      assert(EltBits && "Element size must be of a non-zero size");
      Type *EltTy = IntegerType::get(VTy->getContext(), EltBits);
      return VectorType::get(EltTy, VTy->getNumElements());
    }
  
    /// This static method is like getInteger except that the element types are
    /// twice as wide as the elements in the input type.
    static VectorType *getExtendedElementVectorType(VectorType *VTy) {
      unsigned EltBits = VTy->getElementType()->getPrimitiveSizeInBits();
      Type *EltTy = IntegerType::get(VTy->getContext(), EltBits * 2);
      return VectorType::get(EltTy, VTy->getNumElements());
    }
  
    /// This static method is like getInteger except that the element types are
    /// half as wide as the elements in the input type.
    static VectorType *getTruncatedElementVectorType(VectorType *VTy) {
      unsigned EltBits = VTy->getElementType()->getPrimitiveSizeInBits();
      assert((EltBits & 1) == 0 &&
             "Cannot truncate vector element with odd bit-width");
      Type *EltTy = IntegerType::get(VTy->getContext(), EltBits / 2);
      return VectorType::get(EltTy, VTy->getNumElements());
    }
  
    /// This static method returns a VectorType with half as many elements as the
    /// input type and the same element type.
    static VectorType *getHalfElementsVectorType(VectorType *VTy) {
      unsigned NumElts = VTy->getNumElements();
      assert ((NumElts & 1) == 0 &&
              "Cannot halve vector with odd number of elements.");
      return VectorType::get(VTy->getElementType(), NumElts/2);
    }
  
    /// This static method returns a VectorType with twice as many elements as the
    /// input type and the same element type.
    static VectorType *getDoubleElementsVectorType(VectorType *VTy) {
      unsigned NumElts = VTy->getNumElements();
      return VectorType::get(VTy->getElementType(), NumElts*2);
    }
  
    /// Return true if the specified type is valid as a element type.
    static bool isValidElementType(Type *ElemTy);
  
    /// Return the number of bits in the Vector type.
    /// Returns zero when the vector is a vector of pointers.
    unsigned getBitWidth() const {
      return getNumElements() * getElementType()->getPrimitiveSizeInBits();
    }
  
    /// Methods for support type inquiry through isa, cast, and dyn_cast.
    static bool classof(const Type *T) {
      return T->getTypeID() == VectorTyID;
    }
  };
  
  unsigned Type::getVectorNumElements() const {
    return cast<VectorType>(this)->getNumElements();
  }
  
  /// Class to represent pointers.
  class PointerType : public Type {
    explicit PointerType(Type *ElType, unsigned AddrSpace);
  
    Type *PointeeTy;
  
  public:
    PointerType(const PointerType &) = delete;
    PointerType &operator=(const PointerType &) = delete;
  
    /// This constructs a pointer to an object of the specified type in a numbered
    /// address space.
    static PointerType *get(Type *ElementType, unsigned AddressSpace);
  
    /// This constructs a pointer to an object of the specified type in the
    /// generic address space (address space zero).
    static PointerType *getUnqual(Type *ElementType) {
      return PointerType::get(ElementType, 0);
    }
  
    Type *getElementType() const { return PointeeTy; }
  
    /// Return true if the specified type is valid as a element type.
    static bool isValidElementType(Type *ElemTy);
  
    /// Return true if we can load or store from a pointer to this type.
    static bool isLoadableOrStorableType(Type *ElemTy);
  
    /// Return the address space of the Pointer type.
    inline unsigned getAddressSpace() const { return getSubclassData(); }
  
    /// Implement support type inquiry through isa, cast, and dyn_cast.
    static bool classof(const Type *T) {
      return T->getTypeID() == PointerTyID;
    }
  };
  
  unsigned Type::getPointerAddressSpace() const {
    return cast<PointerType>(getScalarType())->getAddressSpace();
  }
  
  } // end namespace llvh
  
  #endif // LLVM_IR_DERIVEDTYPES_H
  