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      1 //===-- llvm/DerivedTypes.h - Classes for handling data types ---*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file contains the declarations of classes that represent "derived
     11 // types".  These are things like "arrays of x" or "structure of x, y, z" or
     12 // "function returning x taking (y,z) as parameters", etc...
     13 //
     14 // The implementations of these classes live in the Type.cpp file.
     15 //
     16 //===----------------------------------------------------------------------===//
     17 
     18 #ifndef LLVM_IR_DERIVEDTYPES_H
     19 #define LLVM_IR_DERIVEDTYPES_H
     20 
     21 #include "llvm/IR/Type.h"
     22 #include "llvm/Support/Compiler.h"
     23 #include "llvm/Support/DataTypes.h"
     24 
     25 namespace llvm {
     26 
     27 class Value;
     28 class APInt;
     29 class LLVMContext;
     30 template<typename T> class ArrayRef;
     31 class StringRef;
     32 
     33 /// Class to represent integer types. Note that this class is also used to
     34 /// represent the built-in integer types: Int1Ty, Int8Ty, Int16Ty, Int32Ty and
     35 /// Int64Ty.
     36 /// @brief Integer representation type
     37 class IntegerType : public Type {
     38   friend class LLVMContextImpl;
     39 
     40 protected:
     41   explicit IntegerType(LLVMContext &C, unsigned NumBits) : Type(C, IntegerTyID){
     42     setSubclassData(NumBits);
     43   }
     44 public:
     45   /// This enum is just used to hold constants we need for IntegerType.
     46   enum {
     47     MIN_INT_BITS = 1,        ///< Minimum number of bits that can be specified
     48     MAX_INT_BITS = (1<<23)-1 ///< Maximum number of bits that can be specified
     49       ///< Note that bit width is stored in the Type classes SubclassData field
     50       ///< which has 23 bits. This yields a maximum bit width of 8,388,607 bits.
     51   };
     52 
     53   /// This static method is the primary way of constructing an IntegerType.
     54   /// If an IntegerType with the same NumBits value was previously instantiated,
     55   /// that instance will be returned. Otherwise a new one will be created. Only
     56   /// one instance with a given NumBits value is ever created.
     57   /// @brief Get or create an IntegerType instance.
     58   static IntegerType *get(LLVMContext &C, unsigned NumBits);
     59 
     60   /// @brief Get the number of bits in this IntegerType
     61   unsigned getBitWidth() const { return getSubclassData(); }
     62 
     63   /// getBitMask - Return a bitmask with ones set for all of the bits
     64   /// that can be set by an unsigned version of this type.  This is 0xFF for
     65   /// i8, 0xFFFF for i16, etc.
     66   uint64_t getBitMask() const {
     67     return ~uint64_t(0UL) >> (64-getBitWidth());
     68   }
     69 
     70   /// getSignBit - Return a uint64_t with just the most significant bit set (the
     71   /// sign bit, if the value is treated as a signed number).
     72   uint64_t getSignBit() const {
     73     return 1ULL << (getBitWidth()-1);
     74   }
     75 
     76   /// For example, this is 0xFF for an 8 bit integer, 0xFFFF for i16, etc.
     77   /// @returns a bit mask with ones set for all the bits of this type.
     78   /// @brief Get a bit mask for this type.
     79   APInt getMask() const;
     80 
     81   /// This method determines if the width of this IntegerType is a power-of-2
     82   /// in terms of 8 bit bytes.
     83   /// @returns true if this is a power-of-2 byte width.
     84   /// @brief Is this a power-of-2 byte-width IntegerType ?
     85   bool isPowerOf2ByteWidth() const;
     86 
     87   /// Methods for support type inquiry through isa, cast, and dyn_cast.
     88   static inline bool classof(const Type *T) {
     89     return T->getTypeID() == IntegerTyID;
     90   }
     91 };
     92 
     93 
     94 /// FunctionType - Class to represent function types
     95 ///
     96 class FunctionType : public Type {
     97   FunctionType(const FunctionType &) LLVM_DELETED_FUNCTION;
     98   const FunctionType &operator=(const FunctionType &) LLVM_DELETED_FUNCTION;
     99   FunctionType(Type *Result, ArrayRef<Type*> Params, bool IsVarArgs);
    100 
    101 public:
    102   /// FunctionType::get - This static method is the primary way of constructing
    103   /// a FunctionType.
    104   ///
    105   static FunctionType *get(Type *Result,
    106                            ArrayRef<Type*> Params, bool isVarArg);
    107 
    108   /// FunctionType::get - Create a FunctionType taking no parameters.
    109   ///
    110   static FunctionType *get(Type *Result, bool isVarArg);
    111 
    112   /// isValidReturnType - Return true if the specified type is valid as a return
    113   /// type.
    114   static bool isValidReturnType(Type *RetTy);
    115 
    116   /// isValidArgumentType - Return true if the specified type is valid as an
    117   /// argument type.
    118   static bool isValidArgumentType(Type *ArgTy);
    119 
    120   bool isVarArg() const { return getSubclassData()!=0; }
    121   Type *getReturnType() const { return ContainedTys[0]; }
    122 
    123   typedef Type::subtype_iterator param_iterator;
    124   param_iterator param_begin() const { return ContainedTys + 1; }
    125   param_iterator param_end() const { return &ContainedTys[NumContainedTys]; }
    126 
    127   /// Parameter type accessors.
    128   Type *getParamType(unsigned i) const { return ContainedTys[i+1]; }
    129 
    130   /// getNumParams - Return the number of fixed parameters this function type
    131   /// requires.  This does not consider varargs.
    132   ///
    133   unsigned getNumParams() const { return NumContainedTys - 1; }
    134 
    135   /// Methods for support type inquiry through isa, cast, and dyn_cast.
    136   static inline bool classof(const Type *T) {
    137     return T->getTypeID() == FunctionTyID;
    138   }
    139 };
    140 
    141 
    142 /// CompositeType - Common super class of ArrayType, StructType, PointerType
    143 /// and VectorType.
    144 class CompositeType : public Type {
    145 protected:
    146   explicit CompositeType(LLVMContext &C, TypeID tid) : Type(C, tid) { }
    147 public:
    148 
    149   /// getTypeAtIndex - Given an index value into the type, return the type of
    150   /// the element.
    151   ///
    152   Type *getTypeAtIndex(const Value *V);
    153   Type *getTypeAtIndex(unsigned Idx);
    154   bool indexValid(const Value *V) const;
    155   bool indexValid(unsigned Idx) const;
    156 
    157   /// Methods for support type inquiry through isa, cast, and dyn_cast.
    158   static inline bool classof(const Type *T) {
    159     return T->getTypeID() == ArrayTyID ||
    160            T->getTypeID() == StructTyID ||
    161            T->getTypeID() == PointerTyID ||
    162            T->getTypeID() == VectorTyID;
    163   }
    164 };
    165 
    166 
    167 /// StructType - Class to represent struct types.  There are two different kinds
    168 /// of struct types: Literal structs and Identified structs.
    169 ///
    170 /// Literal struct types (e.g. { i32, i32 }) are uniqued structurally, and must
    171 /// always have a body when created.  You can get one of these by using one of
    172 /// the StructType::get() forms.
    173 ///
    174 /// Identified structs (e.g. %foo or %42) may optionally have a name and are not
    175 /// uniqued.  The names for identified structs are managed at the LLVMContext
    176 /// level, so there can only be a single identified struct with a given name in
    177 /// a particular LLVMContext.  Identified structs may also optionally be opaque
    178 /// (have no body specified).  You get one of these by using one of the
    179 /// StructType::create() forms.
    180 ///
    181 /// Independent of what kind of struct you have, the body of a struct type are
    182 /// laid out in memory consequtively with the elements directly one after the
    183 /// other (if the struct is packed) or (if not packed) with padding between the
    184 /// elements as defined by DataLayout (which is required to match what the code
    185 /// generator for a target expects).
    186 ///
    187 class StructType : public CompositeType {
    188   StructType(const StructType &) LLVM_DELETED_FUNCTION;
    189   const StructType &operator=(const StructType &) LLVM_DELETED_FUNCTION;
    190   StructType(LLVMContext &C)
    191     : CompositeType(C, StructTyID), SymbolTableEntry(0) {}
    192   enum {
    193     /// This is the contents of the SubClassData field.
    194     SCDB_HasBody = 1,
    195     SCDB_Packed = 2,
    196     SCDB_IsLiteral = 4,
    197     SCDB_IsSized = 8
    198   };
    199 
    200   /// SymbolTableEntry - For a named struct that actually has a name, this is a
    201   /// pointer to the symbol table entry (maintained by LLVMContext) for the
    202   /// struct.  This is null if the type is an literal struct or if it is
    203   /// a identified type that has an empty name.
    204   ///
    205   void *SymbolTableEntry;
    206 public:
    207   ~StructType() {
    208     delete [] ContainedTys; // Delete the body.
    209   }
    210 
    211   /// StructType::create - This creates an identified struct.
    212   static StructType *create(LLVMContext &Context, StringRef Name);
    213   static StructType *create(LLVMContext &Context);
    214 
    215   static StructType *create(ArrayRef<Type*> Elements,
    216                             StringRef Name,
    217                             bool isPacked = false);
    218   static StructType *create(ArrayRef<Type*> Elements);
    219   static StructType *create(LLVMContext &Context,
    220                             ArrayRef<Type*> Elements,
    221                             StringRef Name,
    222                             bool isPacked = false);
    223   static StructType *create(LLVMContext &Context, ArrayRef<Type*> Elements);
    224   static StructType *create(StringRef Name, Type *elt1, ...) END_WITH_NULL;
    225 
    226   /// StructType::get - This static method is the primary way to create a
    227   /// literal StructType.
    228   static StructType *get(LLVMContext &Context, ArrayRef<Type*> Elements,
    229                          bool isPacked = false);
    230 
    231   /// StructType::get - Create an empty structure type.
    232   ///
    233   static StructType *get(LLVMContext &Context, bool isPacked = false);
    234 
    235   /// StructType::get - This static method is a convenience method for creating
    236   /// structure types by specifying the elements as arguments.  Note that this
    237   /// method always returns a non-packed struct, and requires at least one
    238   /// element type.
    239   static StructType *get(Type *elt1, ...) END_WITH_NULL;
    240 
    241   bool isPacked() const { return (getSubclassData() & SCDB_Packed) != 0; }
    242 
    243   /// isLiteral - Return true if this type is uniqued by structural
    244   /// equivalence, false if it is a struct definition.
    245   bool isLiteral() const { return (getSubclassData() & SCDB_IsLiteral) != 0; }
    246 
    247   /// isOpaque - Return true if this is a type with an identity that has no body
    248   /// specified yet.  These prints as 'opaque' in .ll files.
    249   bool isOpaque() const { return (getSubclassData() & SCDB_HasBody) == 0; }
    250 
    251   /// isSized - Return true if this is a sized type.
    252   bool isSized() const;
    253 
    254   /// hasName - Return true if this is a named struct that has a non-empty name.
    255   bool hasName() const { return SymbolTableEntry != 0; }
    256 
    257   /// getName - Return the name for this struct type if it has an identity.
    258   /// This may return an empty string for an unnamed struct type.  Do not call
    259   /// this on an literal type.
    260   StringRef getName() const;
    261 
    262   /// setName - Change the name of this type to the specified name, or to a name
    263   /// with a suffix if there is a collision.  Do not call this on an literal
    264   /// type.
    265   void setName(StringRef Name);
    266 
    267   /// setBody - Specify a body for an opaque identified type.
    268   void setBody(ArrayRef<Type*> Elements, bool isPacked = false);
    269   void setBody(Type *elt1, ...) END_WITH_NULL;
    270 
    271   /// isValidElementType - Return true if the specified type is valid as a
    272   /// element type.
    273   static bool isValidElementType(Type *ElemTy);
    274 
    275 
    276   // Iterator access to the elements.
    277   typedef Type::subtype_iterator element_iterator;
    278   element_iterator element_begin() const { return ContainedTys; }
    279   element_iterator element_end() const { return &ContainedTys[NumContainedTys];}
    280 
    281   /// isLayoutIdentical - Return true if this is layout identical to the
    282   /// specified struct.
    283   bool isLayoutIdentical(StructType *Other) const;
    284 
    285   /// Random access to the elements
    286   unsigned getNumElements() const { return NumContainedTys; }
    287   Type *getElementType(unsigned N) const {
    288     assert(N < NumContainedTys && "Element number out of range!");
    289     return ContainedTys[N];
    290   }
    291 
    292   /// Methods for support type inquiry through isa, cast, and dyn_cast.
    293   static inline bool classof(const Type *T) {
    294     return T->getTypeID() == StructTyID;
    295   }
    296 };
    297 
    298 /// SequentialType - This is the superclass of the array, pointer and vector
    299 /// type classes.  All of these represent "arrays" in memory.  The array type
    300 /// represents a specifically sized array, pointer types are unsized/unknown
    301 /// size arrays, vector types represent specifically sized arrays that
    302 /// allow for use of SIMD instructions.  SequentialType holds the common
    303 /// features of all, which stem from the fact that all three lay their
    304 /// components out in memory identically.
    305 ///
    306 class SequentialType : public CompositeType {
    307   Type *ContainedType;               ///< Storage for the single contained type.
    308   SequentialType(const SequentialType &) LLVM_DELETED_FUNCTION;
    309   const SequentialType &operator=(const SequentialType &) LLVM_DELETED_FUNCTION;
    310 
    311 protected:
    312   SequentialType(TypeID TID, Type *ElType)
    313     : CompositeType(ElType->getContext(), TID), ContainedType(ElType) {
    314     ContainedTys = &ContainedType;
    315     NumContainedTys = 1;
    316   }
    317 
    318 public:
    319   Type *getElementType() const { return ContainedTys[0]; }
    320 
    321   /// Methods for support type inquiry through isa, cast, and dyn_cast.
    322   static inline bool classof(const Type *T) {
    323     return T->getTypeID() == ArrayTyID ||
    324            T->getTypeID() == PointerTyID ||
    325            T->getTypeID() == VectorTyID;
    326   }
    327 };
    328 
    329 
    330 /// ArrayType - Class to represent array types.
    331 ///
    332 class ArrayType : public SequentialType {
    333   uint64_t NumElements;
    334 
    335   ArrayType(const ArrayType &) LLVM_DELETED_FUNCTION;
    336   const ArrayType &operator=(const ArrayType &) LLVM_DELETED_FUNCTION;
    337   ArrayType(Type *ElType, uint64_t NumEl);
    338 public:
    339   /// ArrayType::get - This static method is the primary way to construct an
    340   /// ArrayType
    341   ///
    342   static ArrayType *get(Type *ElementType, uint64_t NumElements);
    343 
    344   /// isValidElementType - Return true if the specified type is valid as a
    345   /// element type.
    346   static bool isValidElementType(Type *ElemTy);
    347 
    348   uint64_t getNumElements() const { return NumElements; }
    349 
    350   /// Methods for support type inquiry through isa, cast, and dyn_cast.
    351   static inline bool classof(const Type *T) {
    352     return T->getTypeID() == ArrayTyID;
    353   }
    354 };
    355 
    356 /// VectorType - Class to represent vector types.
    357 ///
    358 class VectorType : public SequentialType {
    359   unsigned NumElements;
    360 
    361   VectorType(const VectorType &) LLVM_DELETED_FUNCTION;
    362   const VectorType &operator=(const VectorType &) LLVM_DELETED_FUNCTION;
    363   VectorType(Type *ElType, unsigned NumEl);
    364 public:
    365   /// VectorType::get - This static method is the primary way to construct an
    366   /// VectorType.
    367   ///
    368   static VectorType *get(Type *ElementType, unsigned NumElements);
    369 
    370   /// VectorType::getInteger - This static method gets a VectorType with the
    371   /// same number of elements as the input type, and the element type is an
    372   /// integer type of the same width as the input element type.
    373   ///
    374   static VectorType *getInteger(VectorType *VTy) {
    375     unsigned EltBits = VTy->getElementType()->getPrimitiveSizeInBits();
    376     assert(EltBits && "Element size must be of a non-zero size");
    377     Type *EltTy = IntegerType::get(VTy->getContext(), EltBits);
    378     return VectorType::get(EltTy, VTy->getNumElements());
    379   }
    380 
    381   /// VectorType::getExtendedElementVectorType - This static method is like
    382   /// getInteger except that the element types are twice as wide as the
    383   /// elements in the input type.
    384   ///
    385   static VectorType *getExtendedElementVectorType(VectorType *VTy) {
    386     unsigned EltBits = VTy->getElementType()->getPrimitiveSizeInBits();
    387     Type *EltTy = IntegerType::get(VTy->getContext(), EltBits * 2);
    388     return VectorType::get(EltTy, VTy->getNumElements());
    389   }
    390 
    391   /// VectorType::getTruncatedElementVectorType - This static method is like
    392   /// getInteger except that the element types are half as wide as the
    393   /// elements in the input type.
    394   ///
    395   static VectorType *getTruncatedElementVectorType(VectorType *VTy) {
    396     unsigned EltBits = VTy->getElementType()->getPrimitiveSizeInBits();
    397     assert((EltBits & 1) == 0 &&
    398            "Cannot truncate vector element with odd bit-width");
    399     Type *EltTy = IntegerType::get(VTy->getContext(), EltBits / 2);
    400     return VectorType::get(EltTy, VTy->getNumElements());
    401   }
    402 
    403   /// isValidElementType - Return true if the specified type is valid as a
    404   /// element type.
    405   static bool isValidElementType(Type *ElemTy);
    406 
    407   /// @brief Return the number of elements in the Vector type.
    408   unsigned getNumElements() const { return NumElements; }
    409 
    410   /// @brief Return the number of bits in the Vector type.
    411   /// Returns zero when the vector is a vector of pointers.
    412   unsigned getBitWidth() const {
    413     return NumElements * getElementType()->getPrimitiveSizeInBits();
    414   }
    415 
    416   /// Methods for support type inquiry through isa, cast, and dyn_cast.
    417   static inline bool classof(const Type *T) {
    418     return T->getTypeID() == VectorTyID;
    419   }
    420 };
    421 
    422 
    423 /// PointerType - Class to represent pointers.
    424 ///
    425 class PointerType : public SequentialType {
    426   PointerType(const PointerType &) LLVM_DELETED_FUNCTION;
    427   const PointerType &operator=(const PointerType &) LLVM_DELETED_FUNCTION;
    428   explicit PointerType(Type *ElType, unsigned AddrSpace);
    429 public:
    430   /// PointerType::get - This constructs a pointer to an object of the specified
    431   /// type in a numbered address space.
    432   static PointerType *get(Type *ElementType, unsigned AddressSpace);
    433 
    434   /// PointerType::getUnqual - This constructs a pointer to an object of the
    435   /// specified type in the generic address space (address space zero).
    436   static PointerType *getUnqual(Type *ElementType) {
    437     return PointerType::get(ElementType, 0);
    438   }
    439 
    440   /// isValidElementType - Return true if the specified type is valid as a
    441   /// element type.
    442   static bool isValidElementType(Type *ElemTy);
    443 
    444   /// @brief Return the address space of the Pointer type.
    445   inline unsigned getAddressSpace() const { return getSubclassData(); }
    446 
    447   /// Implement support type inquiry through isa, cast, and dyn_cast.
    448   static inline bool classof(const Type *T) {
    449     return T->getTypeID() == PointerTyID;
    450   }
    451 };
    452 
    453 } // End llvm namespace
    454 
    455 #endif
    456