//===- 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 { /// SectionName - This is the name of the section. The referenced memory is /// owned by TargetLoweringObjectFileELF's ELFUniqueMap. StringRef 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 specified. bool IsExplicit; /// EntrySize - The size of each entry in this section. This size only /// makes sense for sections that contain fixed-sized entries. If a /// section does not contain fixed-sized entries 'EntrySize' will be 0. unsigned EntrySize; private: friend class MCContext; MCSectionELF(StringRef Section, unsigned type, unsigned flags, SectionKind K, bool isExplicit, unsigned entrySize) : MCSection(SV_ELF, K), SectionName(Section), Type(type), Flags(flags), IsExplicit(isExplicit), EntrySize(entrySize) {} ~MCSectionELF(); public: /// ShouldOmitSectionDirective - Decides whether a '.section' directive /// should be printed before the section name bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) 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, // Start of target-specific flags. // Exception Index table SHT_ARM_EXIDX = 0x70000001U, // BPABI DLL dynamic linking pre-emption map SHT_ARM_PREEMPTMAP = 0x70000002U, // Object file compatibility attributes SHT_ARM_ATTRIBUTES = 0x70000003U, SHT_ARM_DEBUGOVERLAY = 0x70000004U, SHT_ARM_OVERLAYSECTION = 0x70000005U, LAST_KNOWN_SECTION_TYPE = SHT_ARM_OVERLAYSECTION }; /// 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, // Start of target-specific flags. /// XCORE_SHF_CP_SECTION - All sections with the "c" flag are grouped /// together by the linker to form the constant pool and the cp register is /// set to the start of the constant pool by the boot code. XCORE_SHF_CP_SECTION = 0x800U, /// XCORE_SHF_DP_SECTION - All sections with the "d" flag are grouped /// together by the linker to form the data section and the dp register is /// set to the start of the section by the boot code. XCORE_SHF_DP_SECTION = 0x1000U }; StringRef getSectionName() const { return SectionName; } unsigned getType() const { return Type; } unsigned getFlags() const { return Flags; } unsigned getEntrySize() const { return EntrySize; } void PrintSwitchToSection(const MCAsmInfo &MAI, raw_ostream &OS) const; virtual bool UseCodeAlign() const; /// isBaseAddressKnownZero - We know that non-allocatable sections (like /// debug info) have a base of zero. virtual bool isBaseAddressKnownZero() const { return (getFlags() & SHF_ALLOC) == 0; } static bool classof(const MCSection *S) { return S->getVariant() == SV_ELF; } static bool classof(const MCSectionELF *) { return true; } // Return the entry size for sections with fixed-width data. static unsigned DetermineEntrySize(SectionKind Kind); }; } // end namespace llvm #endif