//=== MachOWriter.h - Target-independent Mach-O writer support --*- 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 the MachOWriter class. // //===----------------------------------------------------------------------===// #ifndef MACHOWRITER_H #define MACHOWRITER_H #include "llvm/Constants.h" #include "llvm/DerivedTypes.h" #include "llvm/CodeGen/MachineFunctionPass.h" #include "llvm/CodeGen/MachineRelocation.h" #include "llvm/Target/TargetData.h" #include "llvm/Target/TargetMachine.h" #include "llvm/Target/TargetMachOWriterInfo.h" #include <map> namespace llvm { class GlobalVariable; class Mangler; class MachineCodeEmitter; class MachOCodeEmitter; class OutputBuffer; class raw_ostream; /// 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, TargetMachine &TM); }; /// MachOWriter - This class implements the common target-independent code for /// writing Mach-O files. Targets should derive a class from this to /// parameterize the output format. /// class MachOWriter : public MachineFunctionPass { friend class MachOCodeEmitter; public: static char ID; MachineCodeEmitter &getMachineCodeEmitter() const { return *(MachineCodeEmitter*)MCE; } MachOWriter(raw_ostream &O, TargetMachine &TM); virtual ~MachOWriter(); virtual const char *getPassName() const { return "Mach-O Writer"; } typedef std::vector<unsigned char> DataBuffer; protected: /// Output stream to send the resultant object file to. /// raw_ostream &O; /// Target machine description. /// TargetMachine &TM; /// Mang - The object used to perform name mangling for this module. /// Mangler *Mang; /// MCE - The MachineCodeEmitter object that we are exposing to emit machine /// code for functions to the .o file. MachOCodeEmitter *MCE; /// is64Bit/isLittleEndian - This information is inferred from the target /// machine directly, indicating what header values and flags to set. bool is64Bit, isLittleEndian; /// doInitialization - Emit the file header and all of the global variables /// for the module to the Mach-O file. bool doInitialization(Module &M); bool runOnMachineFunction(MachineFunction &MF); /// doFinalization - Now that the module has been completely processed, emit /// the Mach-O file to 'O'. bool doFinalization(Module &M); /// 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. DataBuffer 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; } }; /// Header - An instance of MachOHeader that we will update while we build /// the file, and then emit during finalization. MachOHeader Header; /// 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 { std::string sectname; // name of this section, std::string segname; // segment this section goes in uint64_t addr; // memory address of this section uint64_t size; // size in bytes 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; /// SectionData - The actual data for this section which we are building /// up for emission to the file. DataBuffer SectionData; /// RelocBuffer - A buffer to hold the mach-o relocations before we write /// them out at the appropriate location in the file. DataBuffer RelocBuffer; /// Relocations - The relocations that we have encountered so far in this /// section that we will need to convert to MachORelocation entries when /// the file is written. std::vector<MachineRelocation> Relocations; // 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 §) : sectname(sect), segname(seg), addr(0), size(0), offset(0), align(2), reloff(0), nreloc(0), flags(0), reserved1(0), reserved2(0), reserved3(0) { } }; private: /// SectionList - This is the list of sections that we have emitted to the /// file. Once the file has been completely built, the segment load command /// SectionCommands are constructed from this info. std::vector<MachOSection*> SectionList; /// SectionLookup - This is a mapping from section name to SectionList entry std::map<std::string, MachOSection*> SectionLookup; /// GVSection - This is a mapping from a GlobalValue to a MachOSection, /// to aid in emitting relocations. std::map<GlobalValue*, MachOSection*> GVSection; /// GVOffset - This is a mapping from a GlobalValue to an offset from the /// start of the section in which the GV resides, to aid in emitting /// relocations. std::map<GlobalValue*, intptr_t> GVOffset; /// getSection - Return the section with the specified name, creating a new /// section if one does not already exist. MachOSection *getSection(const std::string &seg, const std::string §, unsigned Flags = 0) { MachOSection *MOS = SectionLookup[seg+sect]; if (MOS) return MOS; MOS = new MachOSection(seg, sect); SectionList.push_back(MOS); MOS->Index = SectionList.size(); MOS->flags = MachOSection::S_REGULAR | Flags; SectionLookup[seg+sect] = MOS; return MOS; } MachOSection *getTextSection(bool isCode = true) { if (isCode) return getSection("__TEXT", "__text", MachOSection::S_ATTR_PURE_INSTRUCTIONS | MachOSection::S_ATTR_SOME_INSTRUCTIONS); else return getSection("__TEXT", "__text"); } MachOSection *getBSSSection() { return getSection("__DATA", "__bss", MachOSection::S_ZEROFILL); } MachOSection *getDataSection() { return getSection("__DATA", "__data"); } MachOSection *getConstSection(Constant *C) { const ConstantArray *CVA = dyn_cast<ConstantArray>(C); if (CVA && CVA->isCString()) return getSection("__TEXT", "__cstring", MachOSection::S_CSTRING_LITERALS); const Type *Ty = C->getType(); if (Ty->isPrimitiveType() || Ty->isInteger()) { unsigned Size = TM.getTargetData()->getTypePaddedSize(Ty); switch(Size) { default: break; // Fall through to __TEXT,__const case 4: return getSection("__TEXT", "__literal4", MachOSection::S_4BYTE_LITERALS); case 8: return getSection("__TEXT", "__literal8", MachOSection::S_8BYTE_LITERALS); case 16: return getSection("__TEXT", "__literal16", MachOSection::S_16BYTE_LITERALS); } } return getSection("__TEXT", "__const"); } MachOSection *getJumpTableSection() { if (TM.getRelocationModel() == Reloc::PIC_) return getTextSection(false); else return getSection("__TEXT", "__const"); } /// MachOSymTab - This struct contains information about the offsets and /// size of symbol table information. /// segment. struct MachOSymTab { uint32_t cmd; // LC_SYMTAB uint32_t cmdsize; // sizeof( MachOSymTab ) uint32_t symoff; // symbol table offset uint32_t nsyms; // number of symbol table entries uint32_t stroff; // string table offset uint32_t strsize; // string table size in bytes // Constants for the cmd field // see <mach-o/loader.h> enum { LC_SYMTAB = 0x02 // link-edit stab symbol table info }; MachOSymTab() : cmd(LC_SYMTAB), cmdsize(6 * sizeof(uint32_t)), symoff(0), nsyms(0), stroff(0), strsize(0) { } }; /// 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) { } }; /// SymTab - The "stab" style symbol table information MachOSymTab SymTab; /// DySymTab - symbol table info for the dynamic link editor MachODySymTab DySymTab; struct MachOSymCmp { // 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 bool PartitionByLocal(const MachOSym &Sym); /// PartitionByDefined - Simple boolean predicate that returns true if Sym /// is defined in this module. static bool PartitionByDefined(const MachOSym &Sym); protected: /// SymbolTable - This is the list of symbols we have emitted to the file. /// This actually gets rearranged before emission to the file (to put the /// local symbols first in the list). std::vector<MachOSym> SymbolTable; /// SymT - A buffer to hold the symbol table before we write it out at the /// appropriate location in the file. DataBuffer SymT; /// StrT - A buffer to hold the string table before we write it out at the /// appropriate location in the file. DataBuffer StrT; /// PendingSyms - This is a list of externally defined symbols that we have /// been asked to emit, but have not seen a reference to. When a reference /// is seen, the symbol will move from this list to the SymbolTable. std::vector<GlobalValue*> PendingGlobals; /// DynamicSymbolTable - This is just a vector of indices into /// SymbolTable to aid in emitting the DYSYMTAB load command. std::vector<unsigned> DynamicSymbolTable; static void InitMem(const Constant *C, void *Addr, intptr_t Offset, const TargetData *TD, std::vector<MachineRelocation> &MRs); private: void AddSymbolToSection(MachOSection *MOS, GlobalVariable *GV); void EmitGlobal(GlobalVariable *GV); void EmitHeaderAndLoadCommands(); void EmitSections(); void BufferSymbolAndStringTable(); void CalculateRelocations(MachOSection &MOS); MachineRelocation GetJTRelocation(unsigned Offset, MachineBasicBlock *MBB) const { return TM.getMachOWriterInfo()->GetJTRelocation(Offset, MBB); } /// GetTargetRelocation - Returns the number of relocations. unsigned GetTargetRelocation(MachineRelocation &MR, unsigned FromIdx, unsigned ToAddr, unsigned ToIndex, OutputBuffer &RelocOut, OutputBuffer &SecOut, bool Scattered, bool Extern) { return TM.getMachOWriterInfo()->GetTargetRelocation(MR, FromIdx, ToAddr, ToIndex, RelocOut, SecOut, Scattered, Extern); } }; } #endif