1 //===- MCSectionELF.h - ELF Machine Code Sections ---------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares the MCSectionELF class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_MC_MCSECTIONELF_H
15 #define LLVM_MC_MCSECTIONELF_H
17 #include "llvm/MC/MCSection.h"
21 /// MCSectionELF - This represents a section on linux, lots of unix variants
22 /// and some bare metal systems.
23 class MCSectionELF : public MCSection {
24 std::string SectionName;
26 /// Type - This is the sh_type field of a section, drawn from the enums below.
29 /// Flags - This is the sh_flags field of a section, drawn from the enums.
33 /// HasCrazyBSS - PPC/Linux doesn't support the .bss directive, it
34 /// needs .section .bss. TODO: replace this with a TAI method.
37 /// IsExplicit - Indicates that this section comes from globals with an
38 /// explicit section specfied.
41 MCSectionELF(const StringRef &Section, unsigned T, unsigned F,
42 SectionKind K, bool hasCrazyBSS, bool isExplicit)
43 : MCSection(K), SectionName(Section.str()), Type(T), Flags(F),
44 HasCrazyBSS(hasCrazyBSS), IsExplicit(isExplicit) {}
47 static MCSectionELF *Create(const StringRef &Section, unsigned Type,
48 unsigned Flags, SectionKind K,
49 bool hasCrazyBSS, bool isExplicit,
52 /// ShouldOmitSectionDirective - Decides whether a '.section' directive
53 /// should be printed before the section name
54 bool ShouldOmitSectionDirective(const char *Name) const;
56 /// ShouldPrintSectionType - Only prints the section type if supported
57 bool ShouldPrintSectionType(unsigned Ty) const;
59 /// IsCommon - True if this section contains only common symbols
60 bool IsCommon() const;
62 /// These are the section type and flags fields. An ELF section can have
63 /// only one Type, but can have more than one of the flags specified.
65 /// Valid section types.
67 // This value marks the section header as inactive.
70 // Holds information defined by the program, with custom format and meaning.
73 // This section holds a symbol table.
76 // The section holds a string table.
79 // The section holds relocation entries with explicit addends.
82 // The section holds a symbol hash table.
85 // Information for dynamic linking.
88 // The section holds information that marks the file in some way.
91 // A section of this type occupies no space in the file.
94 // The section holds relocation entries without explicit addends.
97 // This section type is reserved but has unspecified semantics.
100 // This section holds a symbol table.
103 // This section contains an array of pointers to initialization functions.
104 SHT_INIT_ARRAY = 0x0eU,
106 // This section contains an array of pointers to termination functions.
107 SHT_FINI_ARRAY = 0x0fU,
109 // This section contains an array of pointers to functions that are invoked
110 // before all other initialization functions.
111 SHT_PREINIT_ARRAY = 0x10U,
113 // A section group is a set of sections that are related and that must be
114 // treated specially by the linker.
117 // This section is associated with a section of type SHT_SYMTAB, when the
118 // referenced symbol table contain the escape value SHN_XINDEX
119 SHT_SYMTAB_SHNDX = 0x12U,
121 LAST_KNOWN_SECTION_TYPE = SHT_SYMTAB_SHNDX
124 /// Valid section flags.
126 // The section contains data that should be writable.
129 // The section occupies memory during execution.
132 // The section contains executable machine instructions.
133 SHF_EXECINSTR = 0x4U,
135 // The data in the section may be merged to eliminate duplication.
138 // Elements in the section consist of null-terminated character strings.
141 // A field in this section holds a section header table index.
142 SHF_INFO_LINK = 0x40U,
144 // Adds special ordering requirements for link editors.
145 SHF_LINK_ORDER = 0x80U,
147 // This section requires special OS-specific processing to avoid incorrect
149 SHF_OS_NONCONFORMING = 0x100U,
151 // This section is a member of a section group.
154 // This section holds Thread-Local Storage.
158 StringRef getSectionName() const {
159 return StringRef(SectionName);
162 unsigned getType() const { return Type; }
163 unsigned getFlags() const { return Flags; }
165 virtual void PrintSwitchToSection(const TargetAsmInfo &TAI,
166 raw_ostream &OS) const;
169 } // end namespace llvm