LDSection.h revision 22add6ff3426df1a85089fe6a6e1597ee3b6f300 
1//===- LDSection.h --------------------------------------------------------===//
2//
3//                     The MCLinker Project
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef MCLD_LD_LDSECTION_H
11#define MCLD_LD_LDSECTION_H
12#ifdef ENABLE_UNITTEST
13#include <gtest.h>
14#endif
15
16#include <llvm/Support/DataTypes.h>
17#include <mcld/Support/Allocators.h>
18#include <mcld/Config/Config.h>
19#include <mcld/LD/LDFileFormat.h>
20#include <string>
21
22namespace mcld {
23
24class SectionData;
25class RelocData;
26class EhFrame;
27
28/** \class LDSection
29 *  \brief LDSection represents a section header entry. It is a unified
30 *  abstraction of a section header entry for various file formats.
31 */
32class LDSection
33{
34private:
35  friend class Chunk<LDSection, MCLD_SECTIONS_PER_INPUT>;
36
37  LDSection();
38
39  LDSection(const std::string& pName,
40            LDFileFormat::Kind pKind,
41            uint32_t pType,
42            uint32_t pFlag,
43            uint64_t pSize = 0,
44            uint64_t pAddr = 0);
45
46public:
47  ~LDSection();
48
49  static LDSection* Create(const std::string& pName,
50                           LDFileFormat::Kind pKind,
51                           uint32_t pType,
52                           uint32_t pFlag,
53                           uint64_t pSize = 0,
54                           uint64_t pAddr = 0);
55
56  static void Destroy(LDSection*& pSection);
57
58  static void Clear();
59
60  bool hasOffset() const;
61
62  /// name - the name of this section.
63  const std::string& name() const
64  { return m_Name; }
65
66  /// kind - the kind of this section, such as Text, BSS, GOT, and so on.
67  /// from LDFileFormat::Kind
68  LDFileFormat::Kind kind() const
69  { return m_Kind; }
70
71  /// type - The categorizes the section's contents and semantics. It's
72  /// different from llvm::SectionKind. Type is format-dependent, but
73  /// llvm::SectionKind is format independent and is used for bit-code.
74  ///   In ELF, it is sh_type
75  ///   In MachO, it's type field of struct section::flags
76  uint32_t type() const
77  { return m_Type; }
78
79  /// flag - An integer describes miscellaneous attributes.
80  ///   In ELF, it is sh_flags.
81  ///   In MachO, it's attribute field of struct section::flags
82  uint32_t flag() const
83  { return m_Flag; }
84
85  /// size - An integer specifying the size in bytes of the virtual memory
86  /// occupied by this section.
87  ///   In ELF, if the type() is SHT_NOBITS, this function return zero.
88  ///   Before layouting, output's LDSection::size() should return zero.
89  uint64_t size() const
90  { return m_Size; }
91
92  /// offset - An integer specifying the offset of this section in the file.
93  ///   Before layouting, output's LDSection::offset() should return zero.
94  uint64_t offset() const
95  { return m_Offset; }
96
97  /// addr - An integer specifying the virtual address of this section in the
98  /// virtual image.
99  ///   Before layouting, output's LDSection::offset() should return zero.
100  ///   ELF uses sh_addralign to set alignment constraints. In LLVM, alignment
101  ///   constraint is set in SectionData::setAlignment. addr() contains the
102  ///   original ELF::sh_addr. Modulo sh_addr by sh_addralign is not necessary.
103  ///   MachO uses the same scenario.
104  ///
105  ///   Because addr() in output is changing during linking, MCLinker does not
106  ///   store the address of the output here. The address is in Layout
107  uint64_t addr() const
108  { return m_Addr; }
109
110  /// align - An integer specifying the align of this section in the file.
111  ///   Before layouting, output's LDSection::align() should return zero.
112  uint32_t align() const
113  { return m_Align; }
114
115  size_t index() const
116  { return m_Index; }
117
118  /// getLink - return the Link. When a section A needs the other section B
119  /// during linking or loading, we say B is A's Link section.
120  /// In ELF, InfoLink section control the ElfNN_Shdr::sh_link and sh_info.
121  ///
122  /// @return if the section needs no other sections, return NULL
123  LDSection* getLink()
124  { return m_pLink; }
125
126  const LDSection* getLink() const
127  { return m_pLink; }
128
129  size_t getInfo() const
130  { return m_Info; }
131
132  void setKind(LDFileFormat::Kind pKind)
133  { m_Kind = pKind; }
134
135  void setSize(uint64_t size)
136  { m_Size = size; }
137
138  void setOffset(uint64_t Offset)
139  { m_Offset = Offset; }
140
141  void setAddr(uint64_t addr)
142  { m_Addr = addr; }
143
144  void setAlign(uint32_t align)
145  { m_Align = align; }
146
147  void setFlag(uint32_t flag)
148  { m_Flag = flag; }
149
150  void setType(uint32_t type)
151  { m_Type = type; }
152
153  // -----  SectionData  ----- //
154  const SectionData* getSectionData() const { return m_Data.sect_data; }
155  SectionData*       getSectionData()       { return m_Data.sect_data; }
156
157  void setSectionData(SectionData* pSD) { m_Data.sect_data = pSD; }
158
159  bool hasSectionData() const;
160
161  // ------  RelocData  ------ //
162  const RelocData* getRelocData() const { return m_Data.reloc_data; }
163  RelocData*       getRelocData()       { return m_Data.reloc_data; }
164
165  void setRelocData(RelocData* pRD) { m_Data.reloc_data = pRD; }
166
167  bool hasRelocData() const;
168
169  // ------  EhFrame  ------ //
170  const EhFrame* getEhFrame() const { return m_Data.eh_frame; }
171  EhFrame*       getEhFrame()       { return m_Data.eh_frame; }
172
173  void setEhFrame(EhFrame* pEhFrame) { m_Data.eh_frame = pEhFrame; }
174
175  bool hasEhFrame() const;
176
177  /// setLink - set the sections should link with.
178  /// if pLink is NULL, no Link section is set.
179  void setLink(LDSection* pLink)
180  { m_pLink = pLink; }
181
182  void setInfo(size_t pInfo)
183  { m_Info = pInfo; }
184
185  void setIndex(size_t pIndex)
186  { m_Index = pIndex; }
187
188private:
189  union SectOrRelocData
190  {
191    SectionData* sect_data;
192    RelocData*   reloc_data;
193    EhFrame*     eh_frame;
194  };
195
196private:
197  std::string m_Name;
198
199  LDFileFormat::Kind m_Kind;
200  uint32_t m_Type;
201  uint32_t m_Flag;
202
203  uint64_t m_Size;
204  uint64_t m_Offset;
205  uint64_t m_Addr;
206  uint32_t m_Align;
207
208  size_t m_Info;
209  LDSection* m_pLink;
210
211  /// m_Data - the SectionData or RelocData of this section
212  SectOrRelocData m_Data;
213
214  /// m_Index - the index of the file
215  size_t m_Index;
216
217}; // end of LDSection
218
219} // end namespace mcld
220
221#endif
222
223