LDSection.h revision 533eae20118036f425f27bf0536ef0ccbb090b65 
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
13#include <llvm/Support/DataTypes.h>
14#include <mcld/Support/Allocators.h>
15#include <mcld/Config/Config.h>
16#include <mcld/LD/LDFileFormat.h>
17#include <string>
18
19namespace mcld {
20
21class SectionData;
22class RelocData;
23class EhFrame;
24
25/** \class LDSection
26 *  \brief LDSection represents a section header entry. It is a unified
27 *  abstraction of a section header entry for various file formats.
28 */
29class LDSection
30{
31private:
32  friend class Chunk<LDSection, MCLD_SECTIONS_PER_INPUT>;
33
34  LDSection();
35
36  LDSection(const std::string& pName,
37            LDFileFormat::Kind pKind,
38            uint32_t pType,
39            uint32_t pFlag,
40            uint64_t pSize = 0,
41            uint64_t pAddr = 0);
42
43public:
44  ~LDSection();
45
46  static LDSection* Create(const std::string& pName,
47                           LDFileFormat::Kind pKind,
48                           uint32_t pType,
49                           uint32_t pFlag,
50                           uint64_t pSize = 0,
51                           uint64_t pAddr = 0);
52
53  static void Destroy(LDSection*& pSection);
54
55  static void Clear();
56
57  bool hasOffset() const;
58
59  /// name - the name of this section.
60  const std::string& name() const
61  { return m_Name; }
62
63  /// kind - the kind of this section, such as Text, BSS, GOT, and so on.
64  /// from LDFileFormat::Kind
65  LDFileFormat::Kind kind() const
66  { return m_Kind; }
67
68  /// type - The categorizes the section's contents and semantics. It's
69  /// different from llvm::SectionKind. Type is format-dependent, but
70  /// llvm::SectionKind is format independent and is used for bit-code.
71  ///   In ELF, it is sh_type
72  ///   In MachO, it's type field of struct section::flags
73  uint32_t type() const
74  { return m_Type; }
75
76  /// flag - An integer describes miscellaneous attributes.
77  ///   In ELF, it is sh_flags.
78  ///   In MachO, it's attribute field of struct section::flags
79  uint32_t flag() const
80  { return m_Flag; }
81
82  /// size - An integer specifying the size in bytes of the virtual memory
83  /// occupied by this section.
84  ///   In ELF, if the type() is SHT_NOBITS, this function return zero.
85  ///   Before layouting, output's LDSection::size() should return zero.
86  uint64_t size() const
87  { return m_Size; }
88
89  /// offset - An integer specifying the offset of this section in the file.
90  ///   Before layouting, output's LDSection::offset() should return zero.
91  uint64_t offset() const
92  { return m_Offset; }
93
94  /// addr - An integer specifying the virtual address of this section in the
95  /// virtual image.
96  ///   Before layouting, output's LDSection::offset() should return zero.
97  ///   ELF uses sh_addralign to set alignment constraints. In LLVM, alignment
98  ///   constraint is set in SectionData::setAlignment. addr() contains the
99  ///   original ELF::sh_addr. Modulo sh_addr by sh_addralign is not necessary.
100  ///   MachO uses the same scenario.
101  ///
102  ///   Because addr() in output is changing during linking, MCLinker does not
103  ///   store the address of the output here. The address is in Layout
104  uint64_t addr() const
105  { return m_Addr; }
106
107  /// align - An integer specifying the align of this section in the file.
108  ///   Before layouting, output's LDSection::align() should return zero.
109  uint32_t align() const
110  { return m_Align; }
111
112  size_t index() const
113  { return m_Index; }
114
115  /// getLink - return the Link. When a section A needs the other section B
116  /// during linking or loading, we say B is A's Link section.
117  /// In ELF, InfoLink section control the ElfNN_Shdr::sh_link and sh_info.
118  ///
119  /// @return if the section needs no other sections, return NULL
120  LDSection* getLink()
121  { return m_pLink; }
122
123  const LDSection* getLink() const
124  { return m_pLink; }
125
126  size_t getInfo() const
127  { return m_Info; }
128
129  void setKind(LDFileFormat::Kind pKind)
130  { m_Kind = pKind; }
131
132  void setSize(uint64_t size)
133  { m_Size = size; }
134
135  void setOffset(uint64_t Offset)
136  { m_Offset = Offset; }
137
138  void setAddr(uint64_t addr)
139  { m_Addr = addr; }
140
141  void setAlign(uint32_t align)
142  { m_Align = align; }
143
144  void setFlag(uint32_t flag)
145  { m_Flag = flag; }
146
147  void setType(uint32_t type)
148  { m_Type = type; }
149
150  // -----  SectionData  ----- //
151  const SectionData* getSectionData() const { return m_Data.sect_data; }
152  SectionData*       getSectionData()       { return m_Data.sect_data; }
153
154  void setSectionData(SectionData* pSD) { m_Data.sect_data = pSD; }
155
156  bool hasSectionData() const;
157
158  // ------  RelocData  ------ //
159  const RelocData* getRelocData() const { return m_Data.reloc_data; }
160  RelocData*       getRelocData()       { return m_Data.reloc_data; }
161
162  void setRelocData(RelocData* pRD) { m_Data.reloc_data = pRD; }
163
164  bool hasRelocData() const;
165
166  // ------  EhFrame  ------ //
167  const EhFrame* getEhFrame() const { return m_Data.eh_frame; }
168  EhFrame*       getEhFrame()       { return m_Data.eh_frame; }
169
170  void setEhFrame(EhFrame* pEhFrame) { m_Data.eh_frame = pEhFrame; }
171
172  bool hasEhFrame() const;
173
174  /// setLink - set the sections should link with.
175  /// if pLink is NULL, no Link section is set.
176  void setLink(LDSection* pLink)
177  { m_pLink = pLink; }
178
179  void setInfo(size_t pInfo)
180  { m_Info = pInfo; }
181
182  void setIndex(size_t pIndex)
183  { m_Index = pIndex; }
184
185private:
186  union SectOrRelocData
187  {
188    SectionData* sect_data;
189    RelocData*   reloc_data;
190    EhFrame*     eh_frame;
191  };
192
193private:
194  std::string m_Name;
195
196  LDFileFormat::Kind m_Kind;
197  uint32_t m_Type;
198  uint32_t m_Flag;
199
200  uint64_t m_Size;
201  uint64_t m_Offset;
202  uint64_t m_Addr;
203  uint32_t m_Align;
204
205  size_t m_Info;
206  LDSection* m_pLink;
207
208  /// m_Data - the SectionData or RelocData of this section
209  SectOrRelocData m_Data;
210
211  /// m_Index - the index of the file
212  size_t m_Index;
213
214}; // end of LDSection
215
216} // end namespace mcld
217
218#endif
219
220