TargetData.h revision 34695381d626485a560594f162701088079589df 
1//===-- llvm/Target/TargetData.h - Data size & alignment info ---*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines target properties related to datatype size/offset/alignment
11// information.  It uses lazy annotations to cache information about how
12// structure types are laid out and used.
13//
14// This structure should be created once, filled in if the defaults are not
15// correct and then passed around by const&.  None of the members functions
16// require modification to the object.
17//
18//===----------------------------------------------------------------------===//
19
20#ifndef LLVM_TARGET_TARGETDATA_H
21#define LLVM_TARGET_TARGETDATA_H
22
23#include "llvm/Pass.h"
24#include "llvm/Support/DataTypes.h"
25#include <vector>
26#include <string>
27
28namespace llvm {
29
30class Value;
31class Type;
32class StructType;
33class StructLayout;
34
35class TargetData : public ImmutablePass {
36  bool          LittleEndian;          // Defaults to false
37  unsigned char BoolAlignment;         // Defaults to 1 byte
38  unsigned char ByteAlignment;         // Defaults to 1 byte
39  unsigned char ShortAlignment;        // Defaults to 2 bytes
40  unsigned char IntAlignment;          // Defaults to 4 bytes
41  unsigned char LongAlignment;         // Defaults to 8 bytes
42  unsigned char FloatAlignment;        // Defaults to 4 bytes
43  unsigned char DoubleAlignment;       // Defaults to 8 bytes
44  unsigned char PointerSize;           // Defaults to 8 bytes
45  unsigned char PointerAlignment;      // Defaults to 8 bytes
46
47public:
48  TargetData(const std::string &TargetName = "",
49             bool LittleEndian = false,
50             unsigned char PtrSize = 8,
51             unsigned char PtrAl   = 8, unsigned char DoubleAl = 8,
52             unsigned char FloatAl = 4, unsigned char LongAl   = 8,
53             unsigned char IntAl   = 4, unsigned char ShortAl  = 2,
54             unsigned char ByteAl  = 1, unsigned char BoolAl   = 1);
55
56  // Copy constructor
57  TargetData (const TargetData &TD) :
58    ImmutablePass(),
59    LittleEndian(TD.isLittleEndian()),
60    BoolAlignment(TD.getBoolAlignment()),
61    ByteAlignment(TD.getByteAlignment()),
62    ShortAlignment(TD.getShortAlignment()),
63    IntAlignment(TD.getIntAlignment()),
64    LongAlignment(TD.getLongAlignment()),
65    FloatAlignment(TD.getFloatAlignment()),
66    DoubleAlignment(TD.getDoubleAlignment()),
67    PointerSize(TD.getPointerSize()),
68    PointerAlignment(TD.getPointerAlignment()) {
69  }
70
71  TargetData(const std::string &ToolName, const Module *M);
72  ~TargetData();  // Not virtual, do not subclass this class
73
74  /// Target endianness...
75  bool          isLittleEndian()      const { return     LittleEndian; }
76  bool          isBigEndian()         const { return    !LittleEndian; }
77
78  /// Target alignment constraints
79  unsigned char getBoolAlignment()    const { return    BoolAlignment; }
80  unsigned char getByteAlignment()    const { return    ByteAlignment; }
81  unsigned char getShortAlignment()   const { return   ShortAlignment; }
82  unsigned char getIntAlignment()     const { return     IntAlignment; }
83  unsigned char getLongAlignment()    const { return    LongAlignment; }
84  unsigned char getFloatAlignment()   const { return   FloatAlignment; }
85  unsigned char getDoubleAlignment()  const { return  DoubleAlignment; }
86  unsigned char getPointerAlignment() const { return PointerAlignment; }
87  unsigned char getPointerSize()      const { return      PointerSize; }
88
89  /// getTypeSize - Return the number of bytes necessary to hold the specified
90  /// type.
91  uint64_t getTypeSize(const Type *Ty) const;
92
93  /// getTypeAlignment - Return the minimum required alignment for the specified
94  /// type.
95  unsigned char getTypeAlignment(const Type *Ty) const;
96
97  /// getTypeAlignmentShift - Return the minimum required alignment for the
98  /// specified type, returned as log2 of the value (a shift amount).
99  unsigned char getTypeAlignmentShift(const Type *Ty) const;
100
101  /// getIntPtrType - Return an unsigned integer type that is the same size or
102  /// greater to the host pointer size.
103  const Type *getIntPtrType() const;
104
105  /// getIndexOffset - return the offset from the beginning of the type for the
106  /// specified indices.  This is used to implement getelementptr.
107  ///
108  uint64_t getIndexedOffset(const Type *Ty,
109                            const std::vector<Value*> &Indices) const;
110
111  const StructLayout *getStructLayout(const StructType *Ty) const;
112};
113
114// This object is used to lazily calculate structure layout information for a
115// target machine, based on the TargetData structure.
116//
117class StructLayout {
118public:
119  std::vector<uint64_t> MemberOffsets;
120  uint64_t StructSize;
121  unsigned StructAlignment;
122
123  /// getElementContainingOffset - Given a valid offset into the structure,
124  /// return the structure index that contains it.
125  unsigned getElementContainingOffset(uint64_t Offset) const;
126
127private:
128  friend class TargetData;   // Only TargetData can create this class
129  StructLayout(const StructType *ST, const TargetData &TD);
130};
131
132} // End llvm namespace
133
134#endif
135