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llvm/lib/CodeGen/MachO.h

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//=== MachO.h - Mach-O structures and constants -----------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines MachO .
//
//===----------------------------------------------------------------------===//
#ifndef MACHO_H
#define MACHO_H
#include "llvm/CodeGen/BinaryObject.h"
#include <string>
#include <vector>
namespace llvm {
class GlobalValue;
class TargetAsmInfo;
/// MachOSym - This struct contains information about each symbol that is
/// added to logical symbol table for the module. This is eventually
/// turned into a real symbol table in the file.
struct MachOSym {
const GlobalValue *GV; // The global value this corresponds to.
std::string GVName; // The mangled name of the global value.
uint32_t n_strx; // index into the string table
uint8_t n_type; // type flag
uint8_t n_sect; // section number or NO_SECT
int16_t n_desc; // see <mach-o/stab.h>
uint64_t n_value; // value for this symbol (or stab offset)
// Constants for the n_sect field
// see <mach-o/nlist.h>
enum { NO_SECT = 0 }; // symbol is not in any section
// Constants for the n_type field
// see <mach-o/nlist.h>
enum { N_UNDF = 0x0, // undefined, n_sect == NO_SECT
N_ABS = 0x2, // absolute, n_sect == NO_SECT
N_SECT = 0xe, // defined in section number n_sect
N_PBUD = 0xc, // prebound undefined (defined in a dylib)
N_INDR = 0xa // indirect
};
// The following bits are OR'd into the types above. For example, a type
// of 0x0f would be an external N_SECT symbol (0x0e | 0x01).
enum { N_EXT = 0x01, // external symbol bit
N_PEXT = 0x10 // private external symbol bit
};
// Constants for the n_desc field
// see <mach-o/loader.h>
enum { REFERENCE_FLAG_UNDEFINED_NON_LAZY = 0,
REFERENCE_FLAG_UNDEFINED_LAZY = 1,
REFERENCE_FLAG_DEFINED = 2,
REFERENCE_FLAG_PRIVATE_DEFINED = 3,
REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY = 4,
REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY = 5
};
enum { N_NO_DEAD_STRIP = 0x0020, // symbol is not to be dead stripped
N_WEAK_REF = 0x0040, // symbol is weak referenced
N_WEAK_DEF = 0x0080 // coalesced symbol is a weak definition
};
MachOSym(const GlobalValue *gv, std::string name, uint8_t sect,
const TargetAsmInfo *TAI);
struct SymCmp {
// FIXME: this does not appear to be sorting 'f' after 'F'
bool operator()(const MachOSym &LHS, const MachOSym &RHS) {
return LHS.GVName < RHS.GVName;
}
};
/// PartitionByLocal - Simple boolean predicate that returns true if Sym is
/// a local symbol rather than an external symbol.
static inline bool PartitionByLocal(const MachOSym &Sym) {
return (Sym.n_type & (MachOSym::N_EXT | MachOSym::N_PEXT)) == 0;
}
/// PartitionByDefined - Simple boolean predicate that returns true if Sym is
/// defined in this module.
static inline bool PartitionByDefined(const MachOSym &Sym) {
// FIXME: Do N_ABS or N_INDR count as defined?
return (Sym.n_type & MachOSym::N_SECT) == MachOSym::N_SECT;
}
}; // end struct MachOSym
/// MachOHeader - This struct contains the header information about a
/// specific architecture type/subtype pair that is emitted to the file.
struct MachOHeader {
uint32_t magic; // mach magic number identifier
uint32_t filetype; // type of file
uint32_t ncmds; // number of load commands
uint32_t sizeofcmds; // the size of all the load commands
uint32_t flags; // flags
uint32_t reserved; // 64-bit only
/// HeaderData - The actual data for the header which we are building
/// up for emission to the file.
std::vector<unsigned char> HeaderData;
// Constants for the filetype field
// see <mach-o/loader.h> for additional info on the various types
enum { MH_OBJECT = 1, // relocatable object file
MH_EXECUTE = 2, // demand paged executable file
MH_FVMLIB = 3, // fixed VM shared library file
MH_CORE = 4, // core file
MH_PRELOAD = 5, // preloaded executable file
MH_DYLIB = 6, // dynamically bound shared library
MH_DYLINKER = 7, // dynamic link editor
MH_BUNDLE = 8, // dynamically bound bundle file
MH_DYLIB_STUB = 9, // shared library stub for static linking only
MH_DSYM = 10 // companion file wiht only debug sections
};
// Constants for the flags field
enum { MH_NOUNDEFS = 1 << 0,
// the object file has no undefined references
MH_INCRLINK = 1 << 1,
// the object file is the output of an incremental link against
// a base file and cannot be link edited again
MH_DYLDLINK = 1 << 2,
// the object file is input for the dynamic linker and cannot be
// statically link edited again.
MH_BINDATLOAD = 1 << 3,
// the object file's undefined references are bound by the
// dynamic linker when loaded.
MH_PREBOUND = 1 << 4,
// the file has its dynamic undefined references prebound
MH_SPLIT_SEGS = 1 << 5,
// the file has its read-only and read-write segments split
// see <mach/shared_memory_server.h>
MH_LAZY_INIT = 1 << 6,
// the shared library init routine is to be run lazily via
// catching memory faults to its writable segments (obsolete)
MH_TWOLEVEL = 1 << 7,
// the image is using two-level namespace bindings
MH_FORCE_FLAT = 1 << 8,
// the executable is forcing all images to use flat namespace
// bindings.
MH_NOMULTIDEFS = 1 << 8,
// this umbrella guarantees no multiple definitions of symbols
// in its sub-images so the two-level namespace hints can
// always be used.
MH_NOFIXPREBINDING = 1 << 10,
// do not have dyld notify the prebidning agent about this
// executable.
MH_PREBINDABLE = 1 << 11,
// the binary is not prebound but can have its prebinding
// redone. only used when MH_PREBOUND is not set.
MH_ALLMODSBOUND = 1 << 12,
// indicates that this binary binds to all two-level namespace
// modules of its dependent libraries. Only used when
// MH_PREBINDABLE and MH_TWOLEVEL are both set.
MH_SUBSECTIONS_VIA_SYMBOLS = 1 << 13,
// safe to divide up the sections into sub-sections via symbols
// for dead code stripping.
MH_CANONICAL = 1 << 14,
// the binary has been canonicalized via the unprebind operation
MH_WEAK_DEFINES = 1 << 15,
// the final linked image contains external weak symbols
MH_BINDS_TO_WEAK = 1 << 16,
// the final linked image uses weak symbols
MH_ALLOW_STACK_EXECUTION = 1 << 17
// When this bit is set, all stacks in the task will be given
// stack execution privilege. Only used in MH_EXECUTE filetype
};
MachOHeader() : magic(0), filetype(0), ncmds(0), sizeofcmds(0), flags(0),
reserved(0) {}
/// cmdSize - This routine returns the size of the MachOSection as written
/// to disk, depending on whether the destination is a 64 bit Mach-O file.
unsigned cmdSize(bool is64Bit) const {
if (is64Bit)
return 8 * sizeof(uint32_t);
else
return 7 * sizeof(uint32_t);
}
/// setMagic - This routine sets the appropriate value for the 'magic'
/// field based on pointer size and endianness.
void setMagic(bool isLittleEndian, bool is64Bit) {
if (isLittleEndian)
if (is64Bit) magic = 0xcffaedfe;
else magic = 0xcefaedfe;
else
if (is64Bit) magic = 0xfeedfacf;
else magic = 0xfeedface;
}
}; // end struct MachOHeader
/// MachOSegment - This struct contains the necessary information to
/// emit the load commands for each section in the file.
struct MachOSegment {
uint32_t cmd; // LC_SEGMENT or LC_SEGMENT_64
uint32_t cmdsize; // Total size of this struct and section commands
std::string segname; // segment name
uint64_t vmaddr; // address of this segment
uint64_t vmsize; // size of this segment, may be larger than filesize
uint64_t fileoff; // offset in file
uint64_t filesize; // amount to read from file
uint32_t maxprot; // maximum VM protection
uint32_t initprot; // initial VM protection
uint32_t nsects; // number of sections in this segment
uint32_t flags; // flags
// The following constants are getting pulled in by one of the
// system headers, which creates a neat clash with the enum.
#if !defined(VM_PROT_NONE)
#define VM_PROT_NONE 0x00
#endif
#if !defined(VM_PROT_READ)
#define VM_PROT_READ 0x01
#endif
#if !defined(VM_PROT_WRITE)
#define VM_PROT_WRITE 0x02
#endif
#if !defined(VM_PROT_EXECUTE)
#define VM_PROT_EXECUTE 0x04
#endif
#if !defined(VM_PROT_ALL)
#define VM_PROT_ALL 0x07
#endif
// Constants for the vm protection fields
// see <mach-o/vm_prot.h>
enum { SEG_VM_PROT_NONE = VM_PROT_NONE,
SEG_VM_PROT_READ = VM_PROT_READ, // read permission
SEG_VM_PROT_WRITE = VM_PROT_WRITE, // write permission
SEG_VM_PROT_EXECUTE = VM_PROT_EXECUTE,
SEG_VM_PROT_ALL = VM_PROT_ALL
};
// Constants for the cmd field
// see <mach-o/loader.h>
enum { LC_SEGMENT = 0x01, // segment of this file to be mapped
LC_SEGMENT_64 = 0x19 // 64-bit segment of this file to be mapped
};
/// cmdSize - This routine returns the size of the MachOSection as written
/// to disk, depending on whether the destination is a 64 bit Mach-O file.
unsigned cmdSize(bool is64Bit) const {
if (is64Bit)
return 6 * sizeof(uint32_t) + 4 * sizeof(uint64_t) + 16;
else
return 10 * sizeof(uint32_t) + 16; // addresses only 32 bits
}
MachOSegment(const std::string &seg, bool is64Bit)
: cmd(is64Bit ? LC_SEGMENT_64 : LC_SEGMENT), cmdsize(0), segname(seg),
vmaddr(0), vmsize(0), fileoff(0), filesize(0), maxprot(VM_PROT_ALL),
initprot(VM_PROT_ALL), nsects(0), flags(0) { }
};
/// MachOSection - This struct contains information about each section in a
/// particular segment that is emitted to the file. This is eventually
/// turned into the SectionCommand in the load command for a particlar
/// segment.
struct MachOSection : public BinaryObject {
std::string sectname; // name of this section,
std::string segname; // segment this section goes in
uint64_t addr; // memory address of this section
uint32_t offset; // file offset of this section
uint32_t align; // section alignment (power of 2)
uint32_t reloff; // file offset of relocation entries
uint32_t nreloc; // number of relocation entries
uint32_t flags; // flags (section type and attributes)
uint32_t reserved1; // reserved (for offset or index)
uint32_t reserved2; // reserved (for count or sizeof)
uint32_t reserved3; // reserved (64 bit only)
/// A unique number for this section, which will be used to match symbols
/// to the correct section.
uint32_t Index;
/// RelocBuffer - A buffer to hold the mach-o relocations before we write
/// them out at the appropriate location in the file.
std::vector<unsigned char> RelocBuffer;
// Constants for the section types (low 8 bits of flags field)
// see <mach-o/loader.h>
enum { S_REGULAR = 0,
// regular section
S_ZEROFILL = 1,
// zero fill on demand section
S_CSTRING_LITERALS = 2,
// section with only literal C strings
S_4BYTE_LITERALS = 3,
// section with only 4 byte literals
S_8BYTE_LITERALS = 4,
// section with only 8 byte literals
S_LITERAL_POINTERS = 5,
// section with only pointers to literals
S_NON_LAZY_SYMBOL_POINTERS = 6,
// section with only non-lazy symbol pointers
S_LAZY_SYMBOL_POINTERS = 7,
// section with only lazy symbol pointers
S_SYMBOL_STUBS = 8,
// section with only symbol stubs
// byte size of stub in the reserved2 field
S_MOD_INIT_FUNC_POINTERS = 9,
// section with only function pointers for initialization
S_MOD_TERM_FUNC_POINTERS = 10,
// section with only function pointers for termination
S_COALESCED = 11,
// section contains symbols that are coalesced
S_GB_ZEROFILL = 12,
// zero fill on demand section (that can be larger than 4GB)
S_INTERPOSING = 13,
// section with only pairs of function pointers for interposing
S_16BYTE_LITERALS = 14
// section with only 16 byte literals
};
// Constants for the section flags (high 24 bits of flags field)
// see <mach-o/loader.h>
enum { S_ATTR_PURE_INSTRUCTIONS = 1 << 31,
// section contains only true machine instructions
S_ATTR_NO_TOC = 1 << 30,
// section contains coalesced symbols that are not to be in a
// ranlib table of contents
S_ATTR_STRIP_STATIC_SYMS = 1 << 29,
// ok to strip static symbols in this section in files with the
// MY_DYLDLINK flag
S_ATTR_NO_DEAD_STRIP = 1 << 28,
// no dead stripping
S_ATTR_LIVE_SUPPORT = 1 << 27,
// blocks are live if they reference live blocks
S_ATTR_SELF_MODIFYING_CODE = 1 << 26,
// used with i386 code stubs written on by dyld
S_ATTR_DEBUG = 1 << 25,
// a debug section
S_ATTR_SOME_INSTRUCTIONS = 1 << 10,
// section contains some machine instructions
S_ATTR_EXT_RELOC = 1 << 9,
// section has external relocation entries
S_ATTR_LOC_RELOC = 1 << 8
// section has local relocation entries
};
/// cmdSize - This routine returns the size of the MachOSection as written
/// to disk, depending on whether the destination is a 64 bit Mach-O file.
unsigned cmdSize(bool is64Bit) const {
if (is64Bit)
return 7 * sizeof(uint32_t) + 2 * sizeof(uint64_t) + 32;
else
return 9 * sizeof(uint32_t) + 32; // addresses only 32 bits
}
MachOSection(const std::string &seg, const std::string &sect)
: BinaryObject(), sectname(sect), segname(seg), addr(0), offset(0),
align(2), reloff(0), nreloc(0), flags(0), reserved1(0), reserved2(0),
reserved3(0) { }
}; // end struct MachOSection
/// MachOSymTab - This struct contains information about the offsets and
/// size of symbol table information.
/// segment.
struct MachODySymTab {
uint32_t cmd; // LC_DYSYMTAB
uint32_t cmdsize; // sizeof(MachODySymTab)
uint32_t ilocalsym; // index to local symbols
uint32_t nlocalsym; // number of local symbols
uint32_t iextdefsym; // index to externally defined symbols
uint32_t nextdefsym; // number of externally defined symbols
uint32_t iundefsym; // index to undefined symbols
uint32_t nundefsym; // number of undefined symbols
uint32_t tocoff; // file offset to table of contents
uint32_t ntoc; // number of entries in table of contents
uint32_t modtaboff; // file offset to module table
uint32_t nmodtab; // number of module table entries
uint32_t extrefsymoff; // offset to referenced symbol table
uint32_t nextrefsyms; // number of referenced symbol table entries
uint32_t indirectsymoff; // file offset to the indirect symbol table
uint32_t nindirectsyms; // number of indirect symbol table entries
uint32_t extreloff; // offset to external relocation entries
uint32_t nextrel; // number of external relocation entries
uint32_t locreloff; // offset to local relocation entries
uint32_t nlocrel; // number of local relocation entries
// Constants for the cmd field
// see <mach-o/loader.h>
enum { LC_DYSYMTAB = 0x0B // dynamic link-edit symbol table info
};
MachODySymTab() : cmd(LC_DYSYMTAB), cmdsize(20 * sizeof(uint32_t)),
ilocalsym(0), nlocalsym(0), iextdefsym(0), nextdefsym(0),
iundefsym(0), nundefsym(0), tocoff(0), ntoc(0), modtaboff(0),
nmodtab(0), extrefsymoff(0), nextrefsyms(0), indirectsymoff(0),
nindirectsyms(0), extreloff(0), nextrel(0), locreloff(0), nlocrel(0) {}
}; // end struct MachODySymTab
} // end namespace llvm
#endif
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