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//===- MCSectionELF.h - ELF Machine Code Sections ---------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the MCSectionELF class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCSECTIONELF_H
#define LLVM_MC_MCSECTIONELF_H
#include "llvm/MC/MCSection.h"
namespace llvm {
/// MCSectionELF - This represents a section on linux, lots of unix variants
/// and some bare metal systems.
class MCSectionELF : public MCSection {
std::string SectionName;
/// Type - This is the sh_type field of a section, drawn from the enums below.
unsigned Type;
/// Flags - This is the sh_flags field of a section, drawn from the enums.
/// below.
unsigned Flags;
/// IsExplicit - Indicates that this section comes from globals with an
/// explicit section specfied.
bool IsExplicit;
protected:
MCSectionELF(const StringRef &Section, unsigned type, unsigned flags,
SectionKind K, bool isExplicit)
: MCSection(K), SectionName(Section.str()), Type(type), Flags(flags),
IsExplicit(isExplicit) {}
public:
static MCSectionELF *Create(const StringRef &Section, unsigned Type,
unsigned Flags, SectionKind K, bool isExplicit,
MCContext &Ctx);
/// ShouldOmitSectionDirective - Decides whether a '.section' directive
/// should be printed before the section name
bool ShouldOmitSectionDirective(const char *Name,
const MCAsmInfo &TAI) const;
/// ShouldPrintSectionType - Only prints the section type if supported
bool ShouldPrintSectionType(unsigned Ty) const;
/// HasCommonSymbols - True if this section holds common symbols, this is
/// indicated on the ELF object file by a symbol with SHN_COMMON section
/// header index.
bool HasCommonSymbols() const;
/// These are the section type and flags fields. An ELF section can have
/// only one Type, but can have more than one of the flags specified.
///
/// Valid section types.
enum {
// This value marks the section header as inactive.
SHT_NULL = 0x00U,
// Holds information defined by the program, with custom format and meaning.
SHT_PROGBITS = 0x01U,
// This section holds a symbol table.
SHT_SYMTAB = 0x02U,
// The section holds a string table.
SHT_STRTAB = 0x03U,
// The section holds relocation entries with explicit addends.
SHT_RELA = 0x04U,
// The section holds a symbol hash table.
SHT_HASH = 0x05U,
// Information for dynamic linking.
SHT_DYNAMIC = 0x06U,
// The section holds information that marks the file in some way.
SHT_NOTE = 0x07U,
// A section of this type occupies no space in the file.
SHT_NOBITS = 0x08U,
// The section holds relocation entries without explicit addends.
SHT_REL = 0x09U,
// This section type is reserved but has unspecified semantics.
SHT_SHLIB = 0x0AU,
// This section holds a symbol table.
SHT_DYNSYM = 0x0BU,
// This section contains an array of pointers to initialization functions.
SHT_INIT_ARRAY = 0x0EU,
// This section contains an array of pointers to termination functions.
SHT_FINI_ARRAY = 0x0FU,
// This section contains an array of pointers to functions that are invoked
// before all other initialization functions.
SHT_PREINIT_ARRAY = 0x10U,
// A section group is a set of sections that are related and that must be
// treated specially by the linker.
SHT_GROUP = 0x11U,
// This section is associated with a section of type SHT_SYMTAB, when the
// referenced symbol table contain the escape value SHN_XINDEX
SHT_SYMTAB_SHNDX = 0x12U,
LAST_KNOWN_SECTION_TYPE = SHT_SYMTAB_SHNDX
};
/// Valid section flags.
enum {
// The section contains data that should be writable.
SHF_WRITE = 0x1U,
// The section occupies memory during execution.
SHF_ALLOC = 0x2U,
// The section contains executable machine instructions.
SHF_EXECINSTR = 0x4U,
// The data in the section may be merged to eliminate duplication.
SHF_MERGE = 0x10U,
// Elements in the section consist of null-terminated character strings.
SHF_STRINGS = 0x20U,
// A field in this section holds a section header table index.
SHF_INFO_LINK = 0x40U,
// Adds special ordering requirements for link editors.
SHF_LINK_ORDER = 0x80U,
// This section requires special OS-specific processing to avoid incorrect
// behavior.
SHF_OS_NONCONFORMING = 0x100U,
// This section is a member of a section group.
SHF_GROUP = 0x200U,
// This section holds Thread-Local Storage.
SHF_TLS = 0x400U,
/// FIRST_TARGET_DEP_FLAG - This is the first flag that subclasses are
/// allowed to specify.
FIRST_TARGET_DEP_FLAG = 0x800U,
/// TARGET_INDEP_SHF - This is the bitmask for all the target independent
/// section flags. Targets can define their own target flags above these.
/// If they do that, they should implement their own MCSectionELF subclasses
/// and implement the virtual method hooks below to handle printing needs.
TARGET_INDEP_SHF = FIRST_TARGET_DEP_FLAG-1U
};
StringRef getSectionName() const {
return StringRef(SectionName);
}
unsigned getType() const { return Type; }
unsigned getFlags() const { return Flags; }
virtual void PrintSwitchToSection(const MCAsmInfo &TAI,
raw_ostream &OS) const;
/// PrintTargetSpecificSectionFlags - Targets that define their own
/// MCSectionELF subclasses with target specific section flags should
/// implement this method if they end up adding letters to the attributes
/// list.
virtual void PrintTargetSpecificSectionFlags(const MCAsmInfo &TAI,
raw_ostream &OS) const {
}
};
} // end namespace llvm
#endif
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