git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165242 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/DataLayout.h

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+//===-- llvm/Target/TargetData.h - Data size & alignment info ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines target properties related to datatype size/offset/alignment
+// information.  It uses lazy annotations to cache information about how
+// structure types are laid out and used.
+//
+// This structure should be created once, filled in if the defaults are not
+// correct and then passed around by const&.  None of the members functions
+// require modification to the object.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TARGET_TARGETDATA_H
+#define LLVM_TARGET_TARGETDATA_H
+
+#include "llvm/Pass.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
+
+class Value;
+class Type;
+class IntegerType;
+class StructType;
+class StructLayout;
+class GlobalVariable;
+class LLVMContext;
+template<typename T>
+class ArrayRef;
+
+/// Enum used to categorize the alignment types stored by TargetAlignElem
+enum AlignTypeEnum {
+  INTEGER_ALIGN = 'i',               ///< Integer type alignment
+  VECTOR_ALIGN = 'v',                ///< Vector type alignment
+  FLOAT_ALIGN = 'f',                 ///< Floating point type alignment
+  AGGREGATE_ALIGN = 'a',             ///< Aggregate alignment
+  STACK_ALIGN = 's'                  ///< Stack objects alignment
+};
+
+/// Target alignment element.
+///
+/// Stores the alignment data associated with a given alignment type (pointer,
+/// integer, vector, float) and type bit width.
+///
+/// @note The unusual order of elements in the structure attempts to reduce
+/// padding and make the structure slightly more cache friendly.
+struct TargetAlignElem {
+  unsigned AlignType    : 8;  ///< Alignment type (AlignTypeEnum)
+  unsigned TypeBitWidth : 24; ///< Type bit width
+  unsigned ABIAlign     : 16; ///< ABI alignment for this type/bitw
+  unsigned PrefAlign    : 16; ///< Pref. alignment for this type/bitw
+
+  /// Initializer
+  static TargetAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
+                             unsigned pref_align, uint32_t bit_width);
+  /// Equality predicate
+  bool operator==(const TargetAlignElem &rhs) const;
+};
+
+/// TargetData - This class holds a parsed version of the target data layout
+/// string in a module and provides methods for querying it.  The target data
+/// layout string is specified *by the target* - a frontend generating LLVM IR
+/// is required to generate the right target data for the target being codegen'd
+/// to.  If some measure of portability is desired, an empty string may be
+/// specified in the module.
+class TargetData : public ImmutablePass {
+private:
+  bool          LittleEndian;          ///< Defaults to false
+  unsigned      PointerMemSize;        ///< Pointer size in bytes
+  unsigned      PointerABIAlign;       ///< Pointer ABI alignment
+  unsigned      PointerPrefAlign;      ///< Pointer preferred alignment
+  unsigned      StackNaturalAlign;     ///< Stack natural alignment
+
+  SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers.
+
+  /// Alignments- Where the primitive type alignment data is stored.
+  ///
+  /// @sa init().
+  /// @note Could support multiple size pointer alignments, e.g., 32-bit
+  /// pointers vs. 64-bit pointers by extending TargetAlignment, but for now,
+  /// we don't.
+  SmallVector<TargetAlignElem, 16> Alignments;
+
+  /// InvalidAlignmentElem - This member is a signal that a requested alignment
+  /// type and bit width were not found in the SmallVector.
+  static const TargetAlignElem InvalidAlignmentElem;
+
+  // The StructType -> StructLayout map.
+  mutable void *LayoutMap;
+
+  //! Set/initialize target alignments
+  void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
+                    unsigned pref_align, uint32_t bit_width);
+  unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
+                            bool ABIAlign, Type *Ty) const;
+  //! Internal helper method that returns requested alignment for type.
+  unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
+
+  /// Valid alignment predicate.
+  ///
+  /// Predicate that tests a TargetAlignElem reference returned by get() against
+  /// InvalidAlignmentElem.
+  bool validAlignment(const TargetAlignElem &align) const {
+    return &align != &InvalidAlignmentElem;
+  }
+
+  /// Initialise a TargetData object with default values, ensure that the
+  /// target data pass is registered.
+  void init();
+
+public:
+  /// Default ctor.
+  ///
+  /// @note This has to exist, because this is a pass, but it should never be
+  /// used.
+  TargetData();
+
+  /// Constructs a TargetData from a specification string. See init().
+  explicit TargetData(StringRef TargetDescription)
+    : ImmutablePass(ID) {
+    std::string errMsg = parseSpecifier(TargetDescription, this);
+    assert(errMsg == "" && "Invalid target data layout string.");
+    (void)errMsg;
+  }
+
+  /// Parses a target data specification string. Returns an error message
+  /// if the string is malformed, or the empty string on success. Optionally
+  /// initialises a TargetData object if passed a non-null pointer.
+  static std::string parseSpecifier(StringRef TargetDescription, TargetData* td = 0);
+
+  /// Initialize target data from properties stored in the module.
+  explicit TargetData(const Module *M);
+
+  TargetData(const TargetData &TD) :
+    ImmutablePass(ID),
+    LittleEndian(TD.isLittleEndian()),
+    PointerMemSize(TD.PointerMemSize),
+    PointerABIAlign(TD.PointerABIAlign),
+    PointerPrefAlign(TD.PointerPrefAlign),
+    LegalIntWidths(TD.LegalIntWidths),
+    Alignments(TD.Alignments),
+    LayoutMap(0)
+  { }
+
+  ~TargetData();  // Not virtual, do not subclass this class
+
+  /// Target endianness...
+  bool isLittleEndian() const { return LittleEndian; }
+  bool isBigEndian() const { return !LittleEndian; }
+
+  /// getStringRepresentation - Return the string representation of the
+  /// TargetData.  This representation is in the same format accepted by the
+  /// string constructor above.
+  std::string getStringRepresentation() const;
+
+  /// isLegalInteger - This function returns true if the specified type is
+  /// known to be a native integer type supported by the CPU.  For example,
+  /// i64 is not native on most 32-bit CPUs and i37 is not native on any known
+  /// one.  This returns false if the integer width is not legal.
+  ///
+  /// The width is specified in bits.
+  ///
+  bool isLegalInteger(unsigned Width) const {
+    for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
+      if (LegalIntWidths[i] == Width)
+        return true;
+    return false;
+  }
+
+  bool isIllegalInteger(unsigned Width) const {
+    return !isLegalInteger(Width);
+  }
+
+  /// Returns true if the given alignment exceeds the natural stack alignment.
+  bool exceedsNaturalStackAlignment(unsigned Align) const {
+    return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
+  }
+
+  /// fitsInLegalInteger - This function returns true if the specified type fits
+  /// in a native integer type supported by the CPU.  For example, if the CPU
+  /// only supports i32 as a native integer type, then i27 fits in a legal
+  // integer type but i45 does not.
+  bool fitsInLegalInteger(unsigned Width) const {
+    for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
+      if (Width <= LegalIntWidths[i])
+        return true;
+    return false;
+  }
+
+  /// Target pointer alignment
+  unsigned getPointerABIAlignment() const { return PointerABIAlign; }
+  /// Return target's alignment for stack-based pointers
+  unsigned getPointerPrefAlignment() const { return PointerPrefAlign; }
+  /// Target pointer size
+  unsigned getPointerSize()         const { return PointerMemSize; }
+  /// Target pointer size, in bits
+  unsigned getPointerSizeInBits()   const { return 8*PointerMemSize; }
+
+  /// Size examples:
+  ///
+  /// Type        SizeInBits  StoreSizeInBits  AllocSizeInBits[*]
+  /// ----        ----------  ---------------  ---------------
+  ///  i1            1           8                8
+  ///  i8            8           8                8
+  ///  i19          19          24               32
+  ///  i32          32          32               32
+  ///  i100        100         104              128
+  ///  i128        128         128              128
+  ///  Float        32          32               32
+  ///  Double       64          64               64
+  ///  X86_FP80     80          80               96
+  ///
+  /// [*] The alloc size depends on the alignment, and thus on the target.
+  ///     These values are for x86-32 linux.
+
+  /// getTypeSizeInBits - Return the number of bits necessary to hold the
+  /// specified type.  For example, returns 36 for i36 and 80 for x86_fp80.
+  uint64_t getTypeSizeInBits(Type* Ty) const;
+
+  /// getTypeStoreSize - Return the maximum number of bytes that may be
+  /// overwritten by storing the specified type.  For example, returns 5
+  /// for i36 and 10 for x86_fp80.
+  uint64_t getTypeStoreSize(Type *Ty) const {
+    return (getTypeSizeInBits(Ty)+7)/8;
+  }
+
+  /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
+  /// overwritten by storing the specified type; always a multiple of 8.  For
+  /// example, returns 40 for i36 and 80 for x86_fp80.
+  uint64_t getTypeStoreSizeInBits(Type *Ty) const {
+    return 8*getTypeStoreSize(Ty);
+  }
+
+  /// getTypeAllocSize - Return the offset in bytes between successive objects
+  /// of the specified type, including alignment padding.  This is the amount
+  /// that alloca reserves for this type.  For example, returns 12 or 16 for
+  /// x86_fp80, depending on alignment.
+  uint64_t getTypeAllocSize(Type* Ty) const {
+    // Round up to the next alignment boundary.
+    return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
+  }
+
+  /// getTypeAllocSizeInBits - Return the offset in bits between successive
+  /// objects of the specified type, including alignment padding; always a
+  /// multiple of 8.  This is the amount that alloca reserves for this type.
+  /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
+  uint64_t getTypeAllocSizeInBits(Type* Ty) const {
+    return 8*getTypeAllocSize(Ty);
+  }
+
+  /// getABITypeAlignment - Return the minimum ABI-required alignment for the
+  /// specified type.
+  unsigned getABITypeAlignment(Type *Ty) const;
+
+  /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
+  /// an integer type of the specified bitwidth.
+  unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
+
+
+  /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
+  /// for the specified type when it is part of a call frame.
+  unsigned getCallFrameTypeAlignment(Type *Ty) const;
+
+
+  /// getPrefTypeAlignment - Return the preferred stack/global alignment for
+  /// the specified type.  This is always at least as good as the ABI alignment.
+  unsigned getPrefTypeAlignment(Type *Ty) const;
+
+  /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
+  /// specified type, returned as log2 of the value (a shift amount).
+  ///
+  unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
+
+  /// getIntPtrType - Return an unsigned integer type that is the same size or
+  /// greater to the host pointer size.
+  ///
+  IntegerType *getIntPtrType(LLVMContext &C) const;
+
+  /// getIndexedOffset - return the offset from the beginning of the type for
+  /// the specified indices.  This is used to implement getelementptr.
+  ///
+  uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
+
+  /// getStructLayout - Return a StructLayout object, indicating the alignment
+  /// of the struct, its size, and the offsets of its fields.  Note that this
+  /// information is lazily cached.
+  const StructLayout *getStructLayout(StructType *Ty) const;
+
+  /// getPreferredAlignment - Return the preferred alignment of the specified
+  /// global.  This includes an explicitly requested alignment (if the global
+  /// has one).
+  unsigned getPreferredAlignment(const GlobalVariable *GV) const;
+
+  /// getPreferredAlignmentLog - Return the preferred alignment of the
+  /// specified global, returned in log form.  This includes an explicitly
+  /// requested alignment (if the global has one).
+  unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
+
+  /// RoundUpAlignment - Round the specified value up to the next alignment
+  /// boundary specified by Alignment.  For example, 7 rounded up to an
+  /// alignment boundary of 4 is 8.  8 rounded up to the alignment boundary of 4
+  /// is 8 because it is already aligned.
+  template <typename UIntTy>
+  static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
+    assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
+    return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
+  }
+
+  static char ID; // Pass identification, replacement for typeid
+};
+
+/// StructLayout - used to lazily calculate structure layout information for a
+/// target machine, based on the TargetData structure.
+///
+class StructLayout {
+  uint64_t StructSize;
+  unsigned StructAlignment;
+  unsigned NumElements;
+  uint64_t MemberOffsets[1];  // variable sized array!
+public:
+
+  uint64_t getSizeInBytes() const {
+    return StructSize;
+  }
+
+  uint64_t getSizeInBits() const {
+    return 8*StructSize;
+  }
+
+  unsigned getAlignment() const {
+    return StructAlignment;
+  }
+
+  /// getElementContainingOffset - Given a valid byte offset into the structure,
+  /// return the structure index that contains it.
+  ///
+  unsigned getElementContainingOffset(uint64_t Offset) const;
+
+  uint64_t getElementOffset(unsigned Idx) const {
+    assert(Idx < NumElements && "Invalid element idx!");
+    return MemberOffsets[Idx];
+  }
+
+  uint64_t getElementOffsetInBits(unsigned Idx) const {
+    return getElementOffset(Idx)*8;
+  }
+
+private:
+  friend class TargetData;   // Only TargetData can create this class
+  StructLayout(StructType *ST, const TargetData &TD);
+};
+
+} // End llvm namespace
+
+#endif