LDSection.h revision abe0db302735bbdf9cd84caee2a36e6c4538fc4d 
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/MC/MCSection.h>
17#include <llvm/MC/MCAssembler.h>
18#include <llvm/ADT/StringRef.h>
19#include <llvm/Support/DataTypes.h>
20#include <mcld/LD/LDFileFormat.h>
21#include <string>
22
23namespace llvm {
24
25class MCAsmInfo;
26class raw_ostream;
27
28} // namespace of llvm
29
30namespace mcld {
31/** \class LDSection
32 *  \brief LDSection represents a section header entry. It is a unified
33 *  abstraction for various file formats.
34 *
35 *  LDSection contains both the format-dependent data and LLVM specific data.
36 *
37 */
38class LDSection : public llvm::MCSection
39{
40public:
41  LDSection(const std::string& pName,
42            LDFileFormat::Kind pKind,
43            uint32_t pType,
44            uint32_t pFlag,
45            uint64_t pSize = 0,
46            uint64_t pOffset = 0,
47            uint64_t pAddr = 0);
48
49  /// name - the name of this section.
50  const std::string& name() const
51  { return m_Name; }
52
53  /// kind - the kind of this section, such as Text, BSS, GOT, and so on.
54  /// from LDFileFormat::Kind
55  LDFileFormat::Kind kind() const
56  { return m_Kind; }
57
58  /// type - The categorizes the section's contents and semantics. It's
59  /// different from llvm::SectionKind. Type is format-dependent, but
60  /// llvm::SectionKind is format independent and is used for bit-code.
61  ///   In ELF, it is sh_type
62  ///   In MachO, it's type field of struct section::flags
63  uint32_t type() const
64  { return m_Type; }
65
66  /// flag - An integer describes miscellaneous attributes.
67  ///   In ELF, it is sh_flags.
68  ///   In MachO, it's attribute field of struct section::flags
69  uint32_t flag() const
70  { return m_Flag; }
71
72  /// size - An integer specifying the size in bytes of the virtual memory
73  /// occupied by this section.
74  ///   In ELF, if the type() is SHT_NOBITS, this function return zero.
75  ///   Before layouting, output's LDSection::size() should return zero.
76  uint64_t size() const
77  { return m_Size; }
78
79  /// offset - An integer specifying the offset of this section in the file.
80  ///   Before layouting, output's LDSection::offset() should return zero.
81  uint64_t offset() const
82  { return m_Offset; }
83
84  /// addr - An integer specifying the virtual address of this section in the
85  /// virtual image.
86  ///   Before layouting, output's LDSection::offset() should return zero.
87  ///   ELF uses sh_addralign to set alignment constraints. In LLVM, alignment
88  ///   constraint is set in MCSectionData::setAlignment. addr() contains the
89  ///   original ELF::sh_addr. Modulo sh_addr by sh_addralign is not necessary.
90  ///   MachO uses the same scenario.
91  ///
92  ///   Because addr() in output is changing during linking, MCLinker does not
93  ///   store the address of the output here. The address is in Layout
94  uint64_t addr() const
95  { return m_Addr; }
96
97  /// align - An integer specifying the align of this section in the file.
98  ///   Before layouting, output's LDSection::align() should return zero.
99  uint32_t align() const
100  { return m_Align; }
101
102  size_t index() const
103  { return m_Index; }
104
105  /// getLink - return the Link. When a section A needs the other section B
106  /// during linking or loading, we say B is A's Link section.
107  /// In ELF, InfoLink section control the ElfNN_Shdr::sh_link and sh_info.
108  ///
109  /// @return if the section needs no other sections, return NULL
110  LDSection* getLink()
111  { return m_pLink; }
112
113  const LDSection* getLink() const
114  { return m_pLink; }
115
116  size_t getInfo() const
117  { return m_Info; }
118
119  void setKind(LDFileFormat::Kind pKind)
120  { m_Kind = pKind; }
121
122  void setSize(uint64_t size)
123  { m_Size = size; }
124
125  void setOffset(uint64_t Offset)
126  { m_Offset = Offset; }
127
128  void setAddr(uint64_t addr)
129  { m_Addr = addr; }
130
131  void setAlign(uint32_t align)
132  { m_Align = align; }
133
134  void setFlag(uint32_t flag)
135  { m_Flag = flag; }
136
137  void setType(uint32_t type)
138  { m_Type = type; }
139
140  static bool classof(const MCSection *S)
141  { return S->getVariant() == SV_LDContext; }
142
143  static bool classof(const LDSection *)
144  { return true; }
145
146  // -----  methods for adapt to llvm::MCSection  ----- //
147  void PrintSwitchToSection(const llvm::MCAsmInfo &MAI,
148                            llvm::raw_ostream &OS) const
149  { }
150
151  bool UseCodeAlign() const
152  { return true; }
153
154  bool isVirtualSection() const
155  { return false; }
156
157  llvm::MCSectionData* getSectionData()
158  { return m_pSectionData; }
159
160  const llvm::MCSectionData* getSectionData() const
161  { return m_pSectionData; }
162
163  void setSectionData(llvm::MCSectionData* pSD)
164  { m_pSectionData = pSD; }
165
166  bool hasSectionData() const
167  { return (NULL != m_pSectionData); }
168
169  /// setLink - set the sections should link with.
170  /// if pLink is NULL, no Link section is set.
171  void setLink(LDSection* pLink)
172  { m_pLink = pLink; }
173
174  void setInfo(size_t pInfo)
175  { m_Info = pInfo; }
176
177  void setIndex(size_t pIndex)
178  { m_Index = pIndex; }
179
180private:
181  std::string m_Name;
182  LDFileFormat::Kind m_Kind;
183  uint32_t m_Type;
184  uint32_t m_Flag;
185
186  uint64_t m_Size;
187  uint64_t m_Offset;
188  uint64_t m_Addr;
189  uint32_t m_Align;
190
191  size_t m_Info;
192  LDSection* m_pLink;
193
194  // pointer to MCSectionData.
195  llvm::MCSectionData* m_pSectionData;
196
197  // the index of the file
198  size_t m_Index;
199
200}; // end of LDSection
201
202} // end namespace mcld
203
204#endif
205