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      1 //===- ELFObjectWriter.h --------------------------------------------------===//
      2 //
      3 //                     The MCLinker Project
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 #ifndef MCLD_LD_ELFOBJECTWRITER_H_
     10 #define MCLD_LD_ELFOBJECTWRITER_H_
     11 #include "mcld/LD/ObjectWriter.h"
     12 #include "mcld/Support/FileOutputBuffer.h"
     13 
     14 #include <cassert>
     15 
     16 namespace mcld {
     17 
     18 class EhFrame;
     19 class GNULDBackend;
     20 class LDSection;
     21 class LinkerConfig;
     22 class Module;
     23 class RelocData;
     24 class SectionData;
     25 
     26 /** \class ELFObjectWriter
     27  *  \brief ELFObjectWriter writes the target-independent parts of object files.
     28  *  ELFObjectWriter reads a MCLDFile and writes into raw_ostream
     29  *
     30  */
     31 class ELFObjectWriter : public ObjectWriter {
     32  public:
     33   ELFObjectWriter(GNULDBackend& pBackend, const LinkerConfig& pConfig);
     34 
     35   ~ELFObjectWriter();
     36 
     37   std::error_code writeObject(Module& pModule, FileOutputBuffer& pOutput);
     38 
     39   size_t getOutputSize(const Module& pModule) const;
     40 
     41  private:
     42   void writeSection(Module& pModule,
     43                     FileOutputBuffer& pOutput,
     44                     LDSection* section);
     45 
     46   const GNULDBackend& target() const { return m_Backend; }
     47   GNULDBackend& target() { return m_Backend; }
     48 
     49   // writeELFHeader - emit ElfXX_Ehdr
     50   template <size_t SIZE>
     51   void writeELFHeader(const LinkerConfig& pConfig,
     52                       const Module& pModule,
     53                       FileOutputBuffer& pOutput) const;
     54 
     55   uint64_t getEntryPoint(const LinkerConfig& pConfig,
     56                          const Module& pModule) const;
     57 
     58   // emitSectionHeader - emit ElfXX_Shdr
     59   template <size_t SIZE>
     60   void emitSectionHeader(const Module& pModule,
     61                          const LinkerConfig& pConfig,
     62                          FileOutputBuffer& pOutput) const;
     63 
     64   // emitProgramHeader - emit ElfXX_Phdr
     65   template <size_t SIZE>
     66   void emitProgramHeader(FileOutputBuffer& pOutput) const;
     67 
     68   // emitShStrTab - emit .shstrtab
     69   void emitShStrTab(const LDSection& pShStrTab,
     70                     const Module& pModule,
     71                     FileOutputBuffer& pOutput);
     72 
     73   void emitSectionData(const LDSection& pSection, MemoryRegion& pRegion) const;
     74 
     75   void emitEhFrame(Module& pModule,
     76                    EhFrame& pFrame,
     77                    MemoryRegion& pRegion) const;
     78 
     79   void emitRelocation(const LinkerConfig& pConfig,
     80                       const LDSection& pSection,
     81                       MemoryRegion& pRegion) const;
     82 
     83   // emitRel - emit ElfXX_Rel
     84   template <size_t SIZE>
     85   void emitRel(const LinkerConfig& pConfig,
     86                const RelocData& pRelocData,
     87                MemoryRegion& pRegion) const;
     88 
     89   // emitRela - emit ElfXX_Rela
     90   template <size_t SIZE>
     91   void emitRela(const LinkerConfig& pConfig,
     92                 const RelocData& pRelocData,
     93                 MemoryRegion& pRegion) const;
     94 
     95   // getSectEntrySize - compute ElfXX_Shdr::sh_entsize
     96   template <size_t SIZE>
     97   uint64_t getSectEntrySize(const LDSection& pSection) const;
     98 
     99   // getSectLink - compute ElfXX_Shdr::sh_link
    100   uint64_t getSectLink(const LDSection& pSection,
    101                        const LinkerConfig& pConfig) const;
    102 
    103   // getSectInfo - compute ElfXX_Shdr::sh_info
    104   uint64_t getSectInfo(const LDSection& pSection) const;
    105 
    106   template <size_t SIZE>
    107   uint64_t getLastStartOffset(const Module& pModule) const {
    108     assert(0 && "Call invalid ELFObjectWriter::getLastStartOffset");
    109     return 0;
    110   }
    111 
    112   void emitSectionData(const SectionData& pSD, MemoryRegion& pRegion) const;
    113 
    114  private:
    115   GNULDBackend& m_Backend;
    116 
    117   const LinkerConfig& m_Config;
    118 };
    119 
    120 template <>
    121 uint64_t ELFObjectWriter::getLastStartOffset<32>(const Module& pModule) const;
    122 
    123 template <>
    124 uint64_t ELFObjectWriter::getLastStartOffset<64>(const Module& pModule) const;
    125 
    126 }  // namespace mcld
    127 
    128 #endif  // MCLD_LD_ELFOBJECTWRITER_H_
    129