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			331 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			331 lines
		
	
	
		
			13 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
//===-- llvm/Target/TargetData.h - Data size & alignment info ---*- C++ -*-===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines target properties related to datatype size/offset/alignment
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// information.  It uses lazy annotations to cache information about how
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// structure types are laid out and used.
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//
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// This structure should be created once, filled in if the defaults are not
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// correct and then passed around by const&.  None of the members functions
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// require modification to the object.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TARGET_TARGETDATA_H
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#define LLVM_TARGET_TARGETDATA_H
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#include "llvm/Pass.h"
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#include "llvm/ADT/SmallVector.h"
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namespace llvm {
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class Value;
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class Type;
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class IntegerType;
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class StructType;
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class StructLayout;
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class GlobalVariable;
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class LLVMContext;
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/// Enum used to categorize the alignment types stored by TargetAlignElem
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enum AlignTypeEnum {
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  INTEGER_ALIGN = 'i',               ///< Integer type alignment
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  VECTOR_ALIGN = 'v',                ///< Vector type alignment
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  FLOAT_ALIGN = 'f',                 ///< Floating point type alignment
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  AGGREGATE_ALIGN = 'a',             ///< Aggregate alignment
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  STACK_ALIGN = 's'                  ///< Stack objects alignment
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};
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/// Target alignment element.
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///
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/// Stores the alignment data associated with a given alignment type (pointer,
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/// integer, vector, float) and type bit width.
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///
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/// @note The unusual order of elements in the structure attempts to reduce
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/// padding and make the structure slightly more cache friendly.
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struct TargetAlignElem {
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  AlignTypeEnum       AlignType : 8;  //< Alignment type (AlignTypeEnum)
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  unsigned char       ABIAlign;       //< ABI alignment for this type/bitw
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  unsigned char       PrefAlign;      //< Pref. alignment for this type/bitw
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  uint32_t            TypeBitWidth;   //< Type bit width
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  /// Initializer
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  static TargetAlignElem get(AlignTypeEnum align_type, unsigned char abi_align,
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                             unsigned char pref_align, uint32_t bit_width);
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  /// Equality predicate
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  bool operator==(const TargetAlignElem &rhs) const;
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};
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class TargetData : public ImmutablePass {
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private:
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  bool          LittleEndian;          ///< Defaults to false
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  unsigned char PointerMemSize;        ///< Pointer size in bytes
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  unsigned char PointerABIAlign;       ///< Pointer ABI alignment
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  unsigned char PointerPrefAlign;      ///< Pointer preferred alignment
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  SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers.
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  /// Alignments- Where the primitive type alignment data is stored.
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  ///
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  /// @sa init().
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  /// @note Could support multiple size pointer alignments, e.g., 32-bit
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  /// pointers vs. 64-bit pointers by extending TargetAlignment, but for now,
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  /// we don't.
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  SmallVector<TargetAlignElem, 16> Alignments;
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  /// InvalidAlignmentElem - This member is a signal that a requested alignment
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  /// type and bit width were not found in the SmallVector.
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  static const TargetAlignElem InvalidAlignmentElem;
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  // The StructType -> StructLayout map.
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  mutable void *LayoutMap;
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  //! Set/initialize target alignments
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  void setAlignment(AlignTypeEnum align_type, unsigned char abi_align,
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                    unsigned char pref_align, uint32_t bit_width);
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  unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
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                            bool ABIAlign, const Type *Ty) const;
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  //! Internal helper method that returns requested alignment for type.
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  unsigned char getAlignment(const Type *Ty, bool abi_or_pref) const;
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  /// Valid alignment predicate.
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  ///
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  /// Predicate that tests a TargetAlignElem reference returned by get() against
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  /// InvalidAlignmentElem.
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  bool validAlignment(const TargetAlignElem &align) const {
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    return &align != &InvalidAlignmentElem;
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  }
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public:
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  /// Default ctor.
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  ///
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  /// @note This has to exist, because this is a pass, but it should never be
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  /// used.
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  TargetData();
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  /// Constructs a TargetData from a specification string. See init().
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  explicit TargetData(StringRef TargetDescription)
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    : ImmutablePass(&ID) {
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    init(TargetDescription);
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  }
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  /// Initialize target data from properties stored in the module.
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  explicit TargetData(const Module *M);
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  TargetData(const TargetData &TD) :
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    ImmutablePass(&ID),
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    LittleEndian(TD.isLittleEndian()),
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    PointerMemSize(TD.PointerMemSize),
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    PointerABIAlign(TD.PointerABIAlign),
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    PointerPrefAlign(TD.PointerPrefAlign),
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    LegalIntWidths(TD.LegalIntWidths),
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    Alignments(TD.Alignments),
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    LayoutMap(0)
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  { }
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  ~TargetData();  // Not virtual, do not subclass this class
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  //! Parse a target data layout string and initialize TargetData alignments.
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  void init(StringRef TargetDescription);
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  /// Target endianness...
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  bool isLittleEndian() const { return LittleEndian; }
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  bool isBigEndian() const { return !LittleEndian; }
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  /// getStringRepresentation - Return the string representation of the
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  /// TargetData.  This representation is in the same format accepted by the
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  /// string constructor above.
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  std::string getStringRepresentation() const;
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  /// isLegalInteger - This function returns true if the specified type is
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  /// known tobe a native integer type supported by the CPU.  For example,
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  /// i64 is not native on most 32-bit CPUs and i37 is not native on any known
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  /// one.  This returns false if the integer width is not legal.
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  ///
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  /// The width is specified in bits.
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  ///
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  bool isLegalInteger(unsigned Width) const {
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    for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
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      if (LegalIntWidths[i] == Width)
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        return true;
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    return false;
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  }
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  bool isIllegalInteger(unsigned Width) const {
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    return !isLegalInteger(Width);
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  }
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  /// Target pointer alignment
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  unsigned char getPointerABIAlignment() const { return PointerABIAlign; }
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  /// Return target's alignment for stack-based pointers
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  unsigned char getPointerPrefAlignment() const { return PointerPrefAlign; }
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  /// Target pointer size
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  unsigned char getPointerSize()         const { return PointerMemSize; }
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  /// Target pointer size, in bits
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  unsigned char getPointerSizeInBits()   const { return 8*PointerMemSize; }
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  /// Size examples:
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  ///
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  /// Type        SizeInBits  StoreSizeInBits  AllocSizeInBits[*]
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  /// ----        ----------  ---------------  ---------------
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  ///  i1            1           8                8
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  ///  i8            8           8                8
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  ///  i19          19          24               32
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  ///  i32          32          32               32
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  ///  i100        100         104              128
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  ///  i128        128         128              128
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  ///  Float        32          32               32
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  ///  Double       64          64               64
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  ///  X86_FP80     80          80               96
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  ///
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  /// [*] The alloc size depends on the alignment, and thus on the target.
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  ///     These values are for x86-32 linux.
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  /// getTypeSizeInBits - Return the number of bits necessary to hold the
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  /// specified type.  For example, returns 36 for i36 and 80 for x86_fp80.
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  uint64_t getTypeSizeInBits(const Type* Ty) const;
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  /// getTypeStoreSize - Return the maximum number of bytes that may be
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  /// overwritten by storing the specified type.  For example, returns 5
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  /// for i36 and 10 for x86_fp80.
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  uint64_t getTypeStoreSize(const Type *Ty) const {
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    return (getTypeSizeInBits(Ty)+7)/8;
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  }
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  /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
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  /// overwritten by storing the specified type; always a multiple of 8.  For
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  /// example, returns 40 for i36 and 80 for x86_fp80.
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  uint64_t getTypeStoreSizeInBits(const Type *Ty) const {
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    return 8*getTypeStoreSize(Ty);
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  }
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  /// getTypeAllocSize - Return the offset in bytes between successive objects
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  /// of the specified type, including alignment padding.  This is the amount
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  /// that alloca reserves for this type.  For example, returns 12 or 16 for
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  /// x86_fp80, depending on alignment.
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  uint64_t getTypeAllocSize(const Type* Ty) const {
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    // Round up to the next alignment boundary.
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    return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
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  }
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  /// getTypeAllocSizeInBits - Return the offset in bits between successive
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  /// objects of the specified type, including alignment padding; always a
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  /// multiple of 8.  This is the amount that alloca reserves for this type.
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  /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
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  uint64_t getTypeAllocSizeInBits(const Type* Ty) const {
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    return 8*getTypeAllocSize(Ty);
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  }
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  /// getABITypeAlignment - Return the minimum ABI-required alignment for the
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  /// specified type.
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  unsigned char getABITypeAlignment(const Type *Ty) const;
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  /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
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  /// for the specified type when it is part of a call frame.
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  unsigned char getCallFrameTypeAlignment(const Type *Ty) const;
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  /// getPrefTypeAlignment - Return the preferred stack/global alignment for
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  /// the specified type.  This is always at least as good as the ABI alignment.
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  unsigned char getPrefTypeAlignment(const Type *Ty) const;
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  /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
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  /// specified type, returned as log2 of the value (a shift amount).
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  ///
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  unsigned char getPreferredTypeAlignmentShift(const Type *Ty) const;
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  /// getIntPtrType - Return an unsigned integer type that is the same size or
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  /// greater to the host pointer size.
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  ///
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  const IntegerType *getIntPtrType(LLVMContext &C) const;
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  /// getIndexedOffset - return the offset from the beginning of the type for
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  /// the specified indices.  This is used to implement getelementptr.
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  ///
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  uint64_t getIndexedOffset(const Type *Ty,
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                            Value* const* Indices, unsigned NumIndices) const;
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  /// getStructLayout - Return a StructLayout object, indicating the alignment
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  /// of the struct, its size, and the offsets of its fields.  Note that this
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  /// information is lazily cached.
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  const StructLayout *getStructLayout(const StructType *Ty) const;
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  /// InvalidateStructLayoutInfo - TargetData speculatively caches StructLayout
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  /// objects.  If a TargetData object is alive when types are being refined and
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  /// removed, this method must be called whenever a StructType is removed to
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  /// avoid a dangling pointer in this cache.
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  void InvalidateStructLayoutInfo(const StructType *Ty) const;
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  /// getPreferredAlignment - Return the preferred alignment of the specified
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  /// global.  This includes an explicitly requested alignment (if the global
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  /// has one).
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  unsigned getPreferredAlignment(const GlobalVariable *GV) const;
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  /// getPreferredAlignmentLog - Return the preferred alignment of the
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  /// specified global, returned in log form.  This includes an explicitly
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  /// requested alignment (if the global has one).
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  unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
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  /// RoundUpAlignment - Round the specified value up to the next alignment
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  /// boundary specified by Alignment.  For example, 7 rounded up to an
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  /// alignment boundary of 4 is 8.  8 rounded up to the alignment boundary of 4
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  /// is 8 because it is already aligned.
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  template <typename UIntTy>
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  static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
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    assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
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    return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
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  }
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  static char ID; // Pass identification, replacement for typeid
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};
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/// StructLayout - used to lazily calculate structure layout information for a
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/// target machine, based on the TargetData structure.
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///
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class StructLayout {
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  uint64_t StructSize;
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  unsigned StructAlignment;
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  unsigned NumElements;
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  uint64_t MemberOffsets[1];  // variable sized array!
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public:
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  uint64_t getSizeInBytes() const {
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    return StructSize;
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  }
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  uint64_t getSizeInBits() const {
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    return 8*StructSize;
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  }
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  unsigned getAlignment() const {
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    return StructAlignment;
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  }
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  /// getElementContainingOffset - Given a valid byte offset into the structure,
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  /// return the structure index that contains it.
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  ///
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  unsigned getElementContainingOffset(uint64_t Offset) const;
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  uint64_t getElementOffset(unsigned Idx) const {
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    assert(Idx < NumElements && "Invalid element idx!");
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    return MemberOffsets[Idx];
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  }
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  uint64_t getElementOffsetInBits(unsigned Idx) const {
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    return getElementOffset(Idx)*8;
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  }
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private:
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  friend class TargetData;   // Only TargetData can create this class
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  StructLayout(const StructType *ST, const TargetData &TD);
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};
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} // End llvm namespace
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#endif
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