lib/CodeGen/MachOWriter.h

   1 //=== MachOWriter.h - Target-independent Mach-O writer support --*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines the MachOWriter class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef MACHOWRITER_H
  15 #define MACHOWRITER_H
  16
  17 #include "llvm/CodeGen/MachineFunctionPass.h"
  18 #include <vector>
  19 #include <map>
  20
  21 namespace llvm {
  22   class Constant;
  23   class GlobalVariable;
  24   class Mangler;
  25   class MachineRelocation;
  26   class MachOCodeEmitter;
  27   struct MachODySymTab;
  28   struct MachOHeader;
  29   struct MachOSection;
  30   struct MachOSym;
  31   class TargetData;
  32   class TargetMachine;
  33   class TargetAsmInfo;
  34   class ObjectCodeEmitter;
  35   class OutputBuffer;
  36   class raw_ostream;
  37
  38   /// MachOWriter - This class implements the common target-independent code for
  39   /// writing Mach-O files.  Targets should derive a class from this to
  40   /// parameterize the output format.
  41   ///
  42   class MachOWriter : public MachineFunctionPass {
  43     friend class MachOCodeEmitter;
  44   public:
  45     static char ID;
  46
  47     ObjectCodeEmitter *getObjectCodeEmitter() {
  48       return reinterpret_cast<ObjectCodeEmitter*>(MachOCE);
  49     }
  50
  51     MachOWriter(raw_ostream &O, TargetMachine &TM);
  52     virtual ~MachOWriter();
  53
  54     virtual const char *getPassName() const {
  55       return "Mach-O Writer";
  56     }
  57
  58   protected:
  59     /// Output stream to send the resultant object file to.
  60     ///
  61     raw_ostream &O;
  62
  63     /// Target machine description.
  64     ///
  65     TargetMachine &TM;
  66
  67     /// Mang - The object used to perform name mangling for this module.
  68     ///
  69     Mangler *Mang;
  70
  71     /// MachOCE - The MachineCodeEmitter object that we are exposing to emit
  72     /// machine code for functions to the .o file.
  73     MachOCodeEmitter *MachOCE;
  74
  75     /// is64Bit/isLittleEndian - This information is inferred from the target
  76     /// machine directly, indicating what header values and flags to set.
  77     bool is64Bit, isLittleEndian;
  78
  79     // Target Asm Info
  80     const TargetAsmInfo *TAI;
  81
  82     /// Header - An instance of MachOHeader that we will update while we build
  83     /// the file, and then emit during finalization.
  84     MachOHeader Header;
  85
  86     /// doInitialization - Emit the file header and all of the global variables
  87     /// for the module to the Mach-O file.
  88     bool doInitialization(Module &M);
  89
  90     bool runOnMachineFunction(MachineFunction &MF);
  91
  92     /// doFinalization - Now that the module has been completely processed, emit
  93     /// the Mach-O file to 'O'.
  94     bool doFinalization(Module &M);
  95
  96   private:
  97
  98     /// SectionList - This is the list of sections that we have emitted to the
  99     /// file.  Once the file has been completely built, the segment load command
 100     /// SectionCommands are constructed from this info.
 101     std::vector<MachOSection*> SectionList;
 102
 103     /// SectionLookup - This is a mapping from section name to SectionList entry
 104     std::map<std::string, MachOSection*> SectionLookup;
 105
 106     /// GVSection - This is a mapping from a GlobalValue to a MachOSection,
 107     /// to aid in emitting relocations.
 108     std::map<GlobalValue*, MachOSection*> GVSection;
 109
 110     /// GVOffset - This is a mapping from a GlobalValue to an offset from the
 111     /// start of the section in which the GV resides, to aid in emitting
 112     /// relocations.
 113     std::map<GlobalValue*, intptr_t> GVOffset;
 114
 115     /// getSection - Return the section with the specified name, creating a new
 116     /// section if one does not already exist.
 117     MachOSection *getSection(const std::string &seg, const std::string &sect,
 118                              unsigned Flags = 0);
 119
 120     /// getTextSection - Return text section with different flags for code/data
 121     MachOSection *getTextSection(bool isCode = true);
 122
 123     MachOSection *getDataSection() {
 124       return getSection("__DATA", "__data");
 125     }
 126
 127     MachOSection *getBSSSection();
 128     MachOSection *getConstSection(Constant *C);
 129     MachOSection *getJumpTableSection();
 130
 131     /// MachOSymTab - This struct contains information about the offsets and
 132     /// size of symbol table information.
 133     /// segment.
 134     struct MachOSymTab {
 135       uint32_t cmd;     // LC_SYMTAB
 136       uint32_t cmdsize; // sizeof( MachOSymTab )
 137       uint32_t symoff;  // symbol table offset
 138       uint32_t nsyms;   // number of symbol table entries
 139       uint32_t stroff;  // string table offset
 140       uint32_t strsize; // string table size in bytes
 141
 142       // Constants for the cmd field
 143       // see <mach-o/loader.h>
 144       enum { LC_SYMTAB = 0x02  // link-edit stab symbol table info
 145       };
 146
 147       MachOSymTab() : cmd(LC_SYMTAB), cmdsize(6 * sizeof(uint32_t)), symoff(0),
 148         nsyms(0), stroff(0), strsize(0) { }
 149     };
 150
 151     /// SymTab - The "stab" style symbol table information
 152     MachOSymTab SymTab;
 153     /// DySymTab - symbol table info for the dynamic link editor
 154     MachODySymTab DySymTab;
 155
 156   protected:
 157
 158     /// SymbolTable - This is the list of symbols we have emitted to the file.
 159     /// This actually gets rearranged before emission to the file (to put the
 160     /// local symbols first in the list).
 161     std::vector<MachOSym> SymbolTable;
 162
 163     /// SymT - A buffer to hold the symbol table before we write it out at the
 164     /// appropriate location in the file.
 165     std::vector<unsigned char> SymT;
 166
 167     /// StrT - A buffer to hold the string table before we write it out at the
 168     /// appropriate location in the file.
 169     std::vector<unsigned char> StrT;
 170
 171     /// PendingSyms - This is a list of externally defined symbols that we have
 172     /// been asked to emit, but have not seen a reference to.  When a reference
 173     /// is seen, the symbol will move from this list to the SymbolTable.
 174     std::vector<GlobalValue*> PendingGlobals;
 175
 176     /// DynamicSymbolTable - This is just a vector of indices into
 177     /// SymbolTable to aid in emitting the DYSYMTAB load command.
 178     std::vector<unsigned> DynamicSymbolTable;
 179
 180     static void InitMem(const Constant *C, uintptr_t Offset,
 181                         const TargetData *TD, MachOSection* mos);
 182
 183   private:
 184     void AddSymbolToSection(MachOSection *MOS, GlobalVariable *GV);
 185     void EmitGlobal(GlobalVariable *GV);
 186     void EmitHeaderAndLoadCommands();
 187     void EmitSections();
 188     void EmitRelocations();
 189     void BufferSymbolAndStringTable();
 190     void CalculateRelocations(MachOSection &MOS);
 191
 192     // GetJTRelocation - Get a relocation a new BB relocation based
 193     // on target information.
 194     MachineRelocation GetJTRelocation(unsigned Offset,
 195                                       MachineBasicBlock *MBB) const;
 196
 197     /// GetTargetRelocation - Returns the number of relocations.
 198     unsigned GetTargetRelocation(MachineRelocation &MR, unsigned FromIdx,
 199                                  unsigned ToAddr, unsigned ToIndex,
 200                                  OutputBuffer &RelocOut, OutputBuffer &SecOut,
 201                                  bool Scattered, bool Extern);
 202   };
 203 }
 204
 205 #endif