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  1. //===- llvm/DataLayout.h - Data size & alignment info -----------*- C++ -*-===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8. //
  9. // This file defines layout properties related to datatype size/offset/alignment
  10. // information.  It uses lazy annotations to cache information about how
  11. // structure types are laid out and used.
  12. //
  13. // This structure should be created once, filled in if the defaults are not
  14. // correct and then passed around by const&.  None of the members functions
  15. // require modification to the object.
  16. //
  17. //===----------------------------------------------------------------------===//
  18.  
  19. #ifndef LLVM_IR_DATALAYOUT_H
  20. #define LLVM_IR_DATALAYOUT_H
  21.  
  22. #include "llvm/ADT/APInt.h"
  23. #include "llvm/ADT/ArrayRef.h"
  24. #include "llvm/ADT/STLExtras.h"
  25. #include "llvm/ADT/SmallVector.h"
  26. #include "llvm/ADT/StringRef.h"
  27. #include "llvm/IR/DerivedTypes.h"
  28. #include "llvm/IR/Type.h"
  29. #include "llvm/Support/Alignment.h"
  30. #include "llvm/Support/Casting.h"
  31. #include "llvm/Support/Compiler.h"
  32. #include "llvm/Support/ErrorHandling.h"
  33. #include "llvm/Support/MathExtras.h"
  34. #include "llvm/Support/TrailingObjects.h"
  35. #include "llvm/Support/TypeSize.h"
  36. #include <cassert>
  37. #include <cstdint>
  38. #include <string>
  39.  
  40. // This needs to be outside of the namespace, to avoid conflict with llvm-c
  41. // decl.
  42. using LLVMTargetDataRef = struct LLVMOpaqueTargetData *;
  43.  
  44. namespace llvm {
  45.  
  46. class GlobalVariable;
  47. class LLVMContext;
  48. class Module;
  49. class StructLayout;
  50. class Triple;
  51. class Value;
  52.  
  53. /// Enum used to categorize the alignment types stored by LayoutAlignElem
  54. enum AlignTypeEnum {
  55.   INVALID_ALIGN = 0,
  56.   INTEGER_ALIGN = 'i',
  57.   VECTOR_ALIGN = 'v',
  58.   FLOAT_ALIGN = 'f',
  59.   AGGREGATE_ALIGN = 'a'
  60. };
  61.  
  62. // FIXME: Currently the DataLayout string carries a "preferred alignment"
  63. // for types. As the DataLayout is module/global, this should likely be
  64. // sunk down to an FTTI element that is queried rather than a global
  65. // preference.
  66.  
  67. /// Layout alignment element.
  68. ///
  69. /// Stores the alignment data associated with a given alignment type (integer,
  70. /// vector, float) and type bit width.
  71. ///
  72. /// \note The unusual order of elements in the structure attempts to reduce
  73. /// padding and make the structure slightly more cache friendly.
  74. struct LayoutAlignElem {
  75.   /// Alignment type from \c AlignTypeEnum
  76.   unsigned AlignType : 8;
  77.   unsigned TypeBitWidth : 24;
  78.   Align ABIAlign;
  79.   Align PrefAlign;
  80.  
  81.   static LayoutAlignElem get(AlignTypeEnum align_type, Align abi_align,
  82.                              Align pref_align, uint32_t bit_width);
  83.  
  84.   bool operator==(const LayoutAlignElem &rhs) const;
  85. };
  86.  
  87. /// Layout pointer alignment element.
  88. ///
  89. /// Stores the alignment data associated with a given pointer and address space.
  90. ///
  91. /// \note The unusual order of elements in the structure attempts to reduce
  92. /// padding and make the structure slightly more cache friendly.
  93. struct PointerAlignElem {
  94.   Align ABIAlign;
  95.   Align PrefAlign;
  96.   uint32_t TypeBitWidth;
  97.   uint32_t AddressSpace;
  98.   uint32_t IndexBitWidth;
  99.  
  100.   /// Initializer
  101.   static PointerAlignElem getInBits(uint32_t AddressSpace, Align ABIAlign,
  102.                                     Align PrefAlign, uint32_t TypeBitWidth,
  103.                                     uint32_t IndexBitWidth);
  104.  
  105.   bool operator==(const PointerAlignElem &rhs) const;
  106. };
  107.  
  108. /// A parsed version of the target data layout string in and methods for
  109. /// querying it.
  110. ///
  111. /// The target data layout string is specified *by the target* - a frontend
  112. /// generating LLVM IR is required to generate the right target data for the
  113. /// target being codegen'd to.
  114. class DataLayout {
  115. public:
  116.   enum class FunctionPtrAlignType {
  117.     /// The function pointer alignment is independent of the function alignment.
  118.     Independent,
  119.     /// The function pointer alignment is a multiple of the function alignment.
  120.     MultipleOfFunctionAlign,
  121.   };
  122. private:
  123.   /// Defaults to false.
  124.   bool BigEndian;
  125.  
  126.   unsigned AllocaAddrSpace;
  127.   MaybeAlign StackNaturalAlign;
  128.   unsigned ProgramAddrSpace;
  129.   unsigned DefaultGlobalsAddrSpace;
  130.  
  131.   MaybeAlign FunctionPtrAlign;
  132.   FunctionPtrAlignType TheFunctionPtrAlignType;
  133.  
  134.   enum ManglingModeT {
  135.     MM_None,
  136.     MM_ELF,
  137.     MM_MachO,
  138.     MM_WinCOFF,
  139.     MM_WinCOFFX86,
  140.     MM_GOFF,
  141.     MM_Mips,
  142.     MM_XCOFF
  143.   };
  144.   ManglingModeT ManglingMode;
  145.  
  146.   SmallVector<unsigned char, 8> LegalIntWidths;
  147.  
  148.   /// Primitive type alignment data. This is sorted by type and bit
  149.   /// width during construction.
  150.   using AlignmentsTy = SmallVector<LayoutAlignElem, 16>;
  151.   AlignmentsTy Alignments;
  152.  
  153.   AlignmentsTy::const_iterator
  154.   findAlignmentLowerBound(AlignTypeEnum AlignType, uint32_t BitWidth) const {
  155.     return const_cast<DataLayout *>(this)->findAlignmentLowerBound(AlignType,
  156.                                                                    BitWidth);
  157.   }
  158.  
  159.   AlignmentsTy::iterator
  160.   findAlignmentLowerBound(AlignTypeEnum AlignType, uint32_t BitWidth);
  161.  
  162.   /// The string representation used to create this DataLayout
  163.   std::string StringRepresentation;
  164.  
  165.   using PointersTy = SmallVector<PointerAlignElem, 8>;
  166.   PointersTy Pointers;
  167.  
  168.   const PointerAlignElem &getPointerAlignElem(uint32_t AddressSpace) const;
  169.  
  170.   // The StructType -> StructLayout map.
  171.   mutable void *LayoutMap = nullptr;
  172.  
  173.   /// Pointers in these address spaces are non-integral, and don't have a
  174.   /// well-defined bitwise representation.
  175.   SmallVector<unsigned, 8> NonIntegralAddressSpaces;
  176.  
  177.   /// Attempts to set the alignment of the given type. Returns an error
  178.   /// description on failure.
  179.   Error setAlignment(AlignTypeEnum align_type, Align abi_align,
  180.                      Align pref_align, uint32_t bit_width);
  181.  
  182.   /// Attempts to set the alignment of a pointer in the given address space.
  183.   /// Returns an error description on failure.
  184.   Error setPointerAlignmentInBits(uint32_t AddrSpace, Align ABIAlign,
  185.                                   Align PrefAlign, uint32_t TypeBitWidth,
  186.                                   uint32_t IndexBitWidth);
  187.  
  188.   /// Internal helper to get alignment for integer of given bitwidth.
  189.   Align getIntegerAlignment(uint32_t BitWidth, bool abi_or_pref) const;
  190.  
  191.   /// Internal helper method that returns requested alignment for type.
  192.   Align getAlignment(Type *Ty, bool abi_or_pref) const;
  193.  
  194.   /// Attempts to parse a target data specification string and reports an error
  195.   /// if the string is malformed.
  196.   Error parseSpecifier(StringRef Desc);
  197.  
  198.   // Free all internal data structures.
  199.   void clear();
  200.  
  201. public:
  202.   /// Constructs a DataLayout from a specification string. See reset().
  203.   explicit DataLayout(StringRef LayoutDescription) {
  204.     reset(LayoutDescription);
  205.   }
  206.  
  207.   /// Initialize target data from properties stored in the module.
  208.   explicit DataLayout(const Module *M);
  209.  
  210.   DataLayout(const DataLayout &DL) { *this = DL; }
  211.  
  212.   ~DataLayout(); // Not virtual, do not subclass this class
  213.  
  214.   DataLayout &operator=(const DataLayout &DL) {
  215.     clear();
  216.     StringRepresentation = DL.StringRepresentation;
  217.     BigEndian = DL.isBigEndian();
  218.     AllocaAddrSpace = DL.AllocaAddrSpace;
  219.     StackNaturalAlign = DL.StackNaturalAlign;
  220.     FunctionPtrAlign = DL.FunctionPtrAlign;
  221.     TheFunctionPtrAlignType = DL.TheFunctionPtrAlignType;
  222.     ProgramAddrSpace = DL.ProgramAddrSpace;
  223.     DefaultGlobalsAddrSpace = DL.DefaultGlobalsAddrSpace;
  224.     ManglingMode = DL.ManglingMode;
  225.     LegalIntWidths = DL.LegalIntWidths;
  226.     Alignments = DL.Alignments;
  227.     Pointers = DL.Pointers;
  228.     NonIntegralAddressSpaces = DL.NonIntegralAddressSpaces;
  229.     return *this;
  230.   }
  231.  
  232.   bool operator==(const DataLayout &Other) const;
  233.   bool operator!=(const DataLayout &Other) const { return !(*this == Other); }
  234.  
  235.   void init(const Module *M);
  236.  
  237.   /// Parse a data layout string (with fallback to default values).
  238.   void reset(StringRef LayoutDescription);
  239.  
  240.   /// Parse a data layout string and return the layout. Return an error
  241.   /// description on failure.
  242.   static Expected<DataLayout> parse(StringRef LayoutDescription);
  243.  
  244.   /// Layout endianness...
  245.   bool isLittleEndian() const { return !BigEndian; }
  246.   bool isBigEndian() const { return BigEndian; }
  247.  
  248.   /// Returns the string representation of the DataLayout.
  249.   ///
  250.   /// This representation is in the same format accepted by the string
  251.   /// constructor above. This should not be used to compare two DataLayout as
  252.   /// different string can represent the same layout.
  253.   const std::string &getStringRepresentation() const {
  254.     return StringRepresentation;
  255.   }
  256.  
  257.   /// Test if the DataLayout was constructed from an empty string.
  258.   bool isDefault() const { return StringRepresentation.empty(); }
  259.  
  260.   /// Returns true if the specified type is known to be a native integer
  261.   /// type supported by the CPU.
  262.   ///
  263.   /// For example, i64 is not native on most 32-bit CPUs and i37 is not native
  264.   /// on any known one. This returns false if the integer width is not legal.
  265.   ///
  266.   /// The width is specified in bits.
  267.   bool isLegalInteger(uint64_t Width) const {
  268.     return llvm::is_contained(LegalIntWidths, Width);
  269.   }
  270.  
  271.   bool isIllegalInteger(uint64_t Width) const { return !isLegalInteger(Width); }
  272.  
  273.   /// Returns true if the given alignment exceeds the natural stack alignment.
  274.   bool exceedsNaturalStackAlignment(Align Alignment) const {
  275.     return StackNaturalAlign && (Alignment > *StackNaturalAlign);
  276.   }
  277.  
  278.   Align getStackAlignment() const {
  279.     assert(StackNaturalAlign && "StackNaturalAlign must be defined");
  280.     return *StackNaturalAlign;
  281.   }
  282.  
  283.   unsigned getAllocaAddrSpace() const { return AllocaAddrSpace; }
  284.  
  285.   /// Returns the alignment of function pointers, which may or may not be
  286.   /// related to the alignment of functions.
  287.   /// \see getFunctionPtrAlignType
  288.   MaybeAlign getFunctionPtrAlign() const { return FunctionPtrAlign; }
  289.  
  290.   /// Return the type of function pointer alignment.
  291.   /// \see getFunctionPtrAlign
  292.   FunctionPtrAlignType getFunctionPtrAlignType() const {
  293.     return TheFunctionPtrAlignType;
  294.   }
  295.  
  296.   unsigned getProgramAddressSpace() const { return ProgramAddrSpace; }
  297.   unsigned getDefaultGlobalsAddressSpace() const {
  298.     return DefaultGlobalsAddrSpace;
  299.   }
  300.  
  301.   bool hasMicrosoftFastStdCallMangling() const {
  302.     return ManglingMode == MM_WinCOFFX86;
  303.   }
  304.  
  305.   /// Returns true if symbols with leading question marks should not receive IR
  306.   /// mangling. True for Windows mangling modes.
  307.   bool doNotMangleLeadingQuestionMark() const {
  308.     return ManglingMode == MM_WinCOFF || ManglingMode == MM_WinCOFFX86;
  309.   }
  310.  
  311.   bool hasLinkerPrivateGlobalPrefix() const { return ManglingMode == MM_MachO; }
  312.  
  313.   StringRef getLinkerPrivateGlobalPrefix() const {
  314.     if (ManglingMode == MM_MachO)
  315.       return "l";
  316.     return "";
  317.   }
  318.  
  319.   char getGlobalPrefix() const {
  320.     switch (ManglingMode) {
  321.     case MM_None:
  322.     case MM_ELF:
  323.     case MM_GOFF:
  324.     case MM_Mips:
  325.     case MM_WinCOFF:
  326.     case MM_XCOFF:
  327.       return '\0';
  328.     case MM_MachO:
  329.     case MM_WinCOFFX86:
  330.       return '_';
  331.     }
  332.     llvm_unreachable("invalid mangling mode");
  333.   }
  334.  
  335.   StringRef getPrivateGlobalPrefix() const {
  336.     switch (ManglingMode) {
  337.     case MM_None:
  338.       return "";
  339.     case MM_ELF:
  340.     case MM_WinCOFF:
  341.       return ".L";
  342.     case MM_GOFF:
  343.       return "@";
  344.     case MM_Mips:
  345.       return "$";
  346.     case MM_MachO:
  347.     case MM_WinCOFFX86:
  348.       return "L";
  349.     case MM_XCOFF:
  350.       return "L..";
  351.     }
  352.     llvm_unreachable("invalid mangling mode");
  353.   }
  354.  
  355.   static const char *getManglingComponent(const Triple &T);
  356.  
  357.   /// Returns true if the specified type fits in a native integer type
  358.   /// supported by the CPU.
  359.   ///
  360.   /// For example, if the CPU only supports i32 as a native integer type, then
  361.   /// i27 fits in a legal integer type but i45 does not.
  362.   bool fitsInLegalInteger(unsigned Width) const {
  363.     for (unsigned LegalIntWidth : LegalIntWidths)
  364.       if (Width <= LegalIntWidth)
  365.         return true;
  366.     return false;
  367.   }
  368.  
  369.   /// Layout pointer alignment
  370.   Align getPointerABIAlignment(unsigned AS) const;
  371.  
  372.   /// Return target's alignment for stack-based pointers
  373.   /// FIXME: The defaults need to be removed once all of
  374.   /// the backends/clients are updated.
  375.   Align getPointerPrefAlignment(unsigned AS = 0) const;
  376.  
  377.   /// Layout pointer size in bytes, rounded up to a whole
  378.   /// number of bytes.
  379.   /// FIXME: The defaults need to be removed once all of
  380.   /// the backends/clients are updated.
  381.   unsigned getPointerSize(unsigned AS = 0) const;
  382.  
  383.   /// Returns the maximum index size over all address spaces.
  384.   unsigned getMaxIndexSize() const;
  385.  
  386.   // Index size in bytes used for address calculation,
  387.   /// rounded up to a whole number of bytes.
  388.   unsigned getIndexSize(unsigned AS) const;
  389.  
  390.   /// Return the address spaces containing non-integral pointers.  Pointers in
  391.   /// this address space don't have a well-defined bitwise representation.
  392.   ArrayRef<unsigned> getNonIntegralAddressSpaces() const {
  393.     return NonIntegralAddressSpaces;
  394.   }
  395.  
  396.   bool isNonIntegralAddressSpace(unsigned AddrSpace) const {
  397.     ArrayRef<unsigned> NonIntegralSpaces = getNonIntegralAddressSpaces();
  398.     return is_contained(NonIntegralSpaces, AddrSpace);
  399.   }
  400.  
  401.   bool isNonIntegralPointerType(PointerType *PT) const {
  402.     return isNonIntegralAddressSpace(PT->getAddressSpace());
  403.   }
  404.  
  405.   bool isNonIntegralPointerType(Type *Ty) const {
  406.     auto *PTy = dyn_cast<PointerType>(Ty);
  407.     return PTy && isNonIntegralPointerType(PTy);
  408.   }
  409.  
  410.   /// Layout pointer size, in bits
  411.   /// FIXME: The defaults need to be removed once all of
  412.   /// the backends/clients are updated.
  413.   unsigned getPointerSizeInBits(unsigned AS = 0) const {
  414.     return getPointerAlignElem(AS).TypeBitWidth;
  415.   }
  416.  
  417.   /// Returns the maximum index size over all address spaces.
  418.   unsigned getMaxIndexSizeInBits() const {
  419.     return getMaxIndexSize() * 8;
  420.   }
  421.  
  422.   /// Size in bits of index used for address calculation in getelementptr.
  423.   unsigned getIndexSizeInBits(unsigned AS) const {
  424.     return getPointerAlignElem(AS).IndexBitWidth;
  425.   }
  426.  
  427.   /// Layout pointer size, in bits, based on the type.  If this function is
  428.   /// called with a pointer type, then the type size of the pointer is returned.
  429.   /// If this function is called with a vector of pointers, then the type size
  430.   /// of the pointer is returned.  This should only be called with a pointer or
  431.   /// vector of pointers.
  432.   unsigned getPointerTypeSizeInBits(Type *) const;
  433.  
  434.   /// Layout size of the index used in GEP calculation.
  435.   /// The function should be called with pointer or vector of pointers type.
  436.   unsigned getIndexTypeSizeInBits(Type *Ty) const;
  437.  
  438.   unsigned getPointerTypeSize(Type *Ty) const {
  439.     return getPointerTypeSizeInBits(Ty) / 8;
  440.   }
  441.  
  442.   /// Size examples:
  443.   ///
  444.   /// Type        SizeInBits  StoreSizeInBits  AllocSizeInBits[*]
  445.   /// ----        ----------  ---------------  ---------------
  446.   ///  i1            1           8                8
  447.   ///  i8            8           8                8
  448.   ///  i19          19          24               32
  449.   ///  i32          32          32               32
  450.   ///  i100        100         104              128
  451.   ///  i128        128         128              128
  452.   ///  Float        32          32               32
  453.   ///  Double       64          64               64
  454.   ///  X86_FP80     80          80               96
  455.   ///
  456.   /// [*] The alloc size depends on the alignment, and thus on the target.
  457.   ///     These values are for x86-32 linux.
  458.  
  459.   /// Returns the number of bits necessary to hold the specified type.
  460.   ///
  461.   /// If Ty is a scalable vector type, the scalable property will be set and
  462.   /// the runtime size will be a positive integer multiple of the base size.
  463.   ///
  464.   /// For example, returns 36 for i36 and 80 for x86_fp80. The type passed must
  465.   /// have a size (Type::isSized() must return true).
  466.   TypeSize getTypeSizeInBits(Type *Ty) const;
  467.  
  468.   /// Returns the maximum number of bytes that may be overwritten by
  469.   /// storing the specified type.
  470.   ///
  471.   /// If Ty is a scalable vector type, the scalable property will be set and
  472.   /// the runtime size will be a positive integer multiple of the base size.
  473.   ///
  474.   /// For example, returns 5 for i36 and 10 for x86_fp80.
  475.   TypeSize getTypeStoreSize(Type *Ty) const {
  476.     TypeSize BaseSize = getTypeSizeInBits(Ty);
  477.     return {divideCeil(BaseSize.getKnownMinValue(), 8), BaseSize.isScalable()};
  478.   }
  479.  
  480.   /// Returns the maximum number of bits that may be overwritten by
  481.   /// storing the specified type; always a multiple of 8.
  482.   ///
  483.   /// If Ty is a scalable vector type, the scalable property will be set and
  484.   /// the runtime size will be a positive integer multiple of the base size.
  485.   ///
  486.   /// For example, returns 40 for i36 and 80 for x86_fp80.
  487.   TypeSize getTypeStoreSizeInBits(Type *Ty) const {
  488.     return 8 * getTypeStoreSize(Ty);
  489.   }
  490.  
  491.   /// Returns true if no extra padding bits are needed when storing the
  492.   /// specified type.
  493.   ///
  494.   /// For example, returns false for i19 that has a 24-bit store size.
  495.   bool typeSizeEqualsStoreSize(Type *Ty) const {
  496.     return getTypeSizeInBits(Ty) == getTypeStoreSizeInBits(Ty);
  497.   }
  498.  
  499.   /// Returns the offset in bytes between successive objects of the
  500.   /// specified type, including alignment padding.
  501.   ///
  502.   /// If Ty is a scalable vector type, the scalable property will be set and
  503.   /// the runtime size will be a positive integer multiple of the base size.
  504.   ///
  505.   /// This is the amount that alloca reserves for this type. For example,
  506.   /// returns 12 or 16 for x86_fp80, depending on alignment.
  507.   TypeSize getTypeAllocSize(Type *Ty) const {
  508.     // Round up to the next alignment boundary.
  509.     return alignTo(getTypeStoreSize(Ty), getABITypeAlign(Ty).value());
  510.   }
  511.  
  512.   /// Returns the offset in bits between successive objects of the
  513.   /// specified type, including alignment padding; always a multiple of 8.
  514.   ///
  515.   /// If Ty is a scalable vector type, the scalable property will be set and
  516.   /// the runtime size will be a positive integer multiple of the base size.
  517.   ///
  518.   /// This is the amount that alloca reserves for this type. For example,
  519.   /// returns 96 or 128 for x86_fp80, depending on alignment.
  520.   TypeSize getTypeAllocSizeInBits(Type *Ty) const {
  521.     return 8 * getTypeAllocSize(Ty);
  522.   }
  523.  
  524.   /// Returns the minimum ABI-required alignment for the specified type.
  525.   /// FIXME: Deprecate this function once migration to Align is over.
  526.   LLVM_DEPRECATED("use getABITypeAlign instead", "getABITypeAlign")
  527.   uint64_t getABITypeAlignment(Type *Ty) const;
  528.  
  529.   /// Returns the minimum ABI-required alignment for the specified type.
  530.   Align getABITypeAlign(Type *Ty) const;
  531.  
  532.   /// Helper function to return `Alignment` if it's set or the result of
  533.   /// `getABITypeAlignment(Ty)`, in any case the result is a valid alignment.
  534.   inline Align getValueOrABITypeAlignment(MaybeAlign Alignment,
  535.                                           Type *Ty) const {
  536.     return Alignment ? *Alignment : getABITypeAlign(Ty);
  537.   }
  538.  
  539.   /// Returns the minimum ABI-required alignment for an integer type of
  540.   /// the specified bitwidth.
  541.   Align getABIIntegerTypeAlignment(unsigned BitWidth) const {
  542.     return getIntegerAlignment(BitWidth, /* abi_or_pref */ true);
  543.   }
  544.  
  545.   /// Returns the preferred stack/global alignment for the specified
  546.   /// type.
  547.   ///
  548.   /// This is always at least as good as the ABI alignment.
  549.   /// FIXME: Deprecate this function once migration to Align is over.
  550.   LLVM_DEPRECATED("use getPrefTypeAlign instead", "getPrefTypeAlign")
  551.   uint64_t getPrefTypeAlignment(Type *Ty) const;
  552.  
  553.   /// Returns the preferred stack/global alignment for the specified
  554.   /// type.
  555.   ///
  556.   /// This is always at least as good as the ABI alignment.
  557.   Align getPrefTypeAlign(Type *Ty) const;
  558.  
  559.   /// Returns an integer type with size at least as big as that of a
  560.   /// pointer in the given address space.
  561.   IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
  562.  
  563.   /// Returns an integer (vector of integer) type with size at least as
  564.   /// big as that of a pointer of the given pointer (vector of pointer) type.
  565.   Type *getIntPtrType(Type *) const;
  566.  
  567.   /// Returns the smallest integer type with size at least as big as
  568.   /// Width bits.
  569.   Type *getSmallestLegalIntType(LLVMContext &C, unsigned Width = 0) const;
  570.  
  571.   /// Returns the largest legal integer type, or null if none are set.
  572.   Type *getLargestLegalIntType(LLVMContext &C) const {
  573.     unsigned LargestSize = getLargestLegalIntTypeSizeInBits();
  574.     return (LargestSize == 0) ? nullptr : Type::getIntNTy(C, LargestSize);
  575.   }
  576.  
  577.   /// Returns the size of largest legal integer type size, or 0 if none
  578.   /// are set.
  579.   unsigned getLargestLegalIntTypeSizeInBits() const;
  580.  
  581.   /// Returns the type of a GEP index.
  582.   /// If it was not specified explicitly, it will be the integer type of the
  583.   /// pointer width - IntPtrType.
  584.   Type *getIndexType(Type *PtrTy) const;
  585.  
  586.   /// Returns the offset from the beginning of the type for the specified
  587.   /// indices.
  588.   ///
  589.   /// Note that this takes the element type, not the pointer type.
  590.   /// This is used to implement getelementptr.
  591.   int64_t getIndexedOffsetInType(Type *ElemTy, ArrayRef<Value *> Indices) const;
  592.  
  593.   /// Get GEP indices to access Offset inside ElemTy. ElemTy is updated to be
  594.   /// the result element type and Offset to be the residual offset.
  595.   SmallVector<APInt> getGEPIndicesForOffset(Type *&ElemTy, APInt &Offset) const;
  596.  
  597.   /// Get single GEP index to access Offset inside ElemTy. Returns std::nullopt
  598.   /// if index cannot be computed, e.g. because the type is not an aggregate.
  599.   /// ElemTy is updated to be the result element type and Offset to be the
  600.   /// residual offset.
  601.   std::optional<APInt> getGEPIndexForOffset(Type *&ElemTy, APInt &Offset) const;
  602.  
  603.   /// Returns a StructLayout object, indicating the alignment of the
  604.   /// struct, its size, and the offsets of its fields.
  605.   ///
  606.   /// Note that this information is lazily cached.
  607.   const StructLayout *getStructLayout(StructType *Ty) const;
  608.  
  609.   /// Returns the preferred alignment of the specified global.
  610.   ///
  611.   /// This includes an explicitly requested alignment (if the global has one).
  612.   Align getPreferredAlign(const GlobalVariable *GV) const;
  613. };
  614.  
  615. inline DataLayout *unwrap(LLVMTargetDataRef P) {
  616.   return reinterpret_cast<DataLayout *>(P);
  617. }
  618.  
  619. inline LLVMTargetDataRef wrap(const DataLayout *P) {
  620.   return reinterpret_cast<LLVMTargetDataRef>(const_cast<DataLayout *>(P));
  621. }
  622.  
  623. /// Used to lazily calculate structure layout information for a target machine,
  624. /// based on the DataLayout structure.
  625. class StructLayout final : public TrailingObjects<StructLayout, uint64_t> {
  626.   uint64_t StructSize;
  627.   Align StructAlignment;
  628.   unsigned IsPadded : 1;
  629.   unsigned NumElements : 31;
  630.  
  631. public:
  632.   uint64_t getSizeInBytes() const { return StructSize; }
  633.  
  634.   uint64_t getSizeInBits() const { return 8 * StructSize; }
  635.  
  636.   Align getAlignment() const { return StructAlignment; }
  637.  
  638.   /// Returns whether the struct has padding or not between its fields.
  639.   /// NB: Padding in nested element is not taken into account.
  640.   bool hasPadding() const { return IsPadded; }
  641.  
  642.   /// Given a valid byte offset into the structure, returns the structure
  643.   /// index that contains it.
  644.   unsigned getElementContainingOffset(uint64_t Offset) const;
  645.  
  646.   MutableArrayRef<uint64_t> getMemberOffsets() {
  647.     return llvm::MutableArrayRef(getTrailingObjects<uint64_t>(),
  648.                                      NumElements);
  649.   }
  650.  
  651.   ArrayRef<uint64_t> getMemberOffsets() const {
  652.     return llvm::ArrayRef(getTrailingObjects<uint64_t>(), NumElements);
  653.   }
  654.  
  655.   uint64_t getElementOffset(unsigned Idx) const {
  656.     assert(Idx < NumElements && "Invalid element idx!");
  657.     return getMemberOffsets()[Idx];
  658.   }
  659.  
  660.   uint64_t getElementOffsetInBits(unsigned Idx) const {
  661.     return getElementOffset(Idx) * 8;
  662.   }
  663.  
  664. private:
  665.   friend class DataLayout; // Only DataLayout can create this class
  666.  
  667.   StructLayout(StructType *ST, const DataLayout &DL);
  668.  
  669.   size_t numTrailingObjects(OverloadToken<uint64_t>) const {
  670.     return NumElements;
  671.   }
  672. };
  673.  
  674. // The implementation of this method is provided inline as it is particularly
  675. // well suited to constant folding when called on a specific Type subclass.
  676. inline TypeSize DataLayout::getTypeSizeInBits(Type *Ty) const {
  677.   assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
  678.   switch (Ty->getTypeID()) {
  679.   case Type::LabelTyID:
  680.     return TypeSize::Fixed(getPointerSizeInBits(0));
  681.   case Type::PointerTyID:
  682.     return TypeSize::Fixed(getPointerSizeInBits(Ty->getPointerAddressSpace()));
  683.   case Type::ArrayTyID: {
  684.     ArrayType *ATy = cast<ArrayType>(Ty);
  685.     return ATy->getNumElements() *
  686.            getTypeAllocSizeInBits(ATy->getElementType());
  687.   }
  688.   case Type::StructTyID:
  689.     // Get the layout annotation... which is lazily created on demand.
  690.     return TypeSize::Fixed(
  691.                         getStructLayout(cast<StructType>(Ty))->getSizeInBits());
  692.   case Type::IntegerTyID:
  693.     return TypeSize::Fixed(Ty->getIntegerBitWidth());
  694.   case Type::HalfTyID:
  695.   case Type::BFloatTyID:
  696.     return TypeSize::Fixed(16);
  697.   case Type::FloatTyID:
  698.     return TypeSize::Fixed(32);
  699.   case Type::DoubleTyID:
  700.   case Type::X86_MMXTyID:
  701.     return TypeSize::Fixed(64);
  702.   case Type::PPC_FP128TyID:
  703.   case Type::FP128TyID:
  704.     return TypeSize::Fixed(128);
  705.   case Type::X86_AMXTyID:
  706.     return TypeSize::Fixed(8192);
  707.   // In memory objects this is always aligned to a higher boundary, but
  708.   // only 80 bits contain information.
  709.   case Type::X86_FP80TyID:
  710.     return TypeSize::Fixed(80);
  711.   case Type::FixedVectorTyID:
  712.   case Type::ScalableVectorTyID: {
  713.     VectorType *VTy = cast<VectorType>(Ty);
  714.     auto EltCnt = VTy->getElementCount();
  715.     uint64_t MinBits = EltCnt.getKnownMinValue() *
  716.                        getTypeSizeInBits(VTy->getElementType()).getFixedValue();
  717.     return TypeSize(MinBits, EltCnt.isScalable());
  718.   }
  719.   case Type::TargetExtTyID: {
  720.     Type *LayoutTy = cast<TargetExtType>(Ty)->getLayoutType();
  721.     return getTypeSizeInBits(LayoutTy);
  722.   }
  723.   default:
  724.     llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
  725.   }
  726. }
  727.  
  728. } // end namespace llvm
  729.  
  730. #endif // LLVM_IR_DATALAYOUT_H
  731.