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      1 //===- MipsLDBackend.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 MIPS_LDBACKEND_H
     10 #define MIPS_LDBACKEND_H
     11 #include <mcld/Target/GNULDBackend.h>
     12 #include "MipsELFDynamic.h"
     13 #include "MipsGOT.h"
     14 
     15 namespace mcld {
     16 
     17 class LinkerConfig;
     18 class OutputRelocSection;
     19 class SectionMap;
     20 class MemoryArea;
     21 class MipsGNUInfo;
     22 
     23 //===----------------------------------------------------------------------===//
     24 /// MipsGNULDBackend - linker backend of Mips target of GNU ELF format
     25 ///
     26 class MipsGNULDBackend : public GNULDBackend
     27 {
     28 public:
     29   typedef std::vector<LDSymbol*> SymbolListType;
     30 
     31 public:
     32   MipsGNULDBackend(const LinkerConfig& pConfig, MipsGNUInfo* pInfo);
     33   ~MipsGNULDBackend();
     34 
     35 public:
     36   /// initTargetSections - initialize target dependent sections in output
     37   void initTargetSections(Module& pModule, ObjectBuilder& pBuilder);
     38 
     39   /// initTargetSymbols - initialize target dependent symbols in output.
     40   void initTargetSymbols(IRBuilder& pBuilder, Module& pModule);
     41 
     42   /// initRelocator - create and initialize Relocator.
     43   bool initRelocator();
     44 
     45   /// getRelocator - return relocator.
     46   Relocator* getRelocator();
     47 
     48   /// preLayout - Backend can do any needed modification before layout
     49   void doPreLayout(IRBuilder& pBuilder);
     50 
     51   /// postLayout - Backend can do any needed modification after layout
     52   void doPostLayout(Module& pModule, IRBuilder& pBuilder);
     53 
     54   /// dynamic - the dynamic section of the target machine.
     55   /// Use co-variant return type to return its own dynamic section.
     56   MipsELFDynamic& dynamic();
     57 
     58   /// dynamic - the dynamic section of the target machine.
     59   /// Use co-variant return type to return its own dynamic section.
     60   const MipsELFDynamic& dynamic() const;
     61 
     62   /// emitSectionData - write out the section data into the memory region.
     63   /// When writers get a LDSection whose kind is LDFileFormat::Target, writers
     64   /// call back target backend to emit the data.
     65   ///
     66   /// Backends handle the target-special tables (plt, gp,...) by themselves.
     67   /// Backend can put the data of the tables in SectionData directly
     68   ///  - LDSection.getSectionData can get the section data.
     69   /// Or, backend can put the data into special data structure
     70   ///  - backend can maintain its own map<LDSection, table> to get the table
     71   /// from given LDSection.
     72   ///
     73   /// @param pSection - the given LDSection
     74   /// @param pRegion - the region to write out data
     75   /// @return the size of the table in the file.
     76   uint64_t emitSectionData(const LDSection& pSection,
     77                            MemoryRegion& pRegion) const;
     78 
     79   /// hasEntryInStrTab - symbol has an entry in a .strtab
     80   bool hasEntryInStrTab(const LDSymbol& pSym) const;
     81 
     82   /// orderSymbolTable - order symbol table before emitting
     83   void orderSymbolTable(Module& pModule);
     84 
     85   MipsGOT& getGOT();
     86   const MipsGOT& getGOT() const;
     87 
     88   OutputRelocSection& getRelDyn();
     89   const OutputRelocSection& getRelDyn() const;
     90 
     91   LDSymbol*             getGOTSymbo()            { return m_pGOTSymbol;    }
     92   const LDSymbol*       getGOTSymbo() const      { return m_pGOTSymbol;    }
     93 
     94   LDSymbol*             getGpDispSymbol()        { return m_pGpDispSymbol; }
     95   const LDSymbol*       getGpDispSymbol() const  { return m_pGpDispSymbol; }
     96 
     97   SymbolListType&       getGlobalGOTSyms()       { return m_GlobalGOTSyms; }
     98   const SymbolListType& getGlobalGOTSyms() const { return m_GlobalGOTSyms; }
     99 
    100   /// getTargetSectionOrder - compute the layout order of ARM target sections
    101   unsigned int getTargetSectionOrder(const LDSection& pSectHdr) const;
    102 
    103   /// finalizeSymbol - finalize the symbol value
    104   bool finalizeTargetSymbols();
    105 
    106   /// allocateCommonSymbols - allocate common symbols in the corresponding
    107   /// sections.
    108   bool allocateCommonSymbols(Module& pModule);
    109 
    110 private:
    111   void defineGOTSymbol(IRBuilder& pBuilder);
    112 
    113   /// emitSymbol32 - emit an ELF32 symbol, override parent's function
    114   void emitSymbol32(llvm::ELF::Elf32_Sym& pSym32,
    115                     LDSymbol& pSymbol,
    116                     char* pStrtab,
    117                     size_t pStrtabsize,
    118                     size_t pSymtabIdx);
    119 
    120   /// getRelEntrySize - the size in BYTE of rel type relocation
    121   size_t getRelEntrySize()
    122   { return 8; }
    123 
    124   /// getRelEntrySize - the size in BYTE of rela type relocation
    125   size_t getRelaEntrySize()
    126   { return 12; }
    127 
    128   /// doCreateProgramHdrs - backend can implement this function to create the
    129   /// target-dependent segments
    130   void doCreateProgramHdrs(Module& pModule);
    131 
    132 private:
    133   Relocator* m_pRelocator;
    134 
    135   MipsGOT* m_pGOT;                      // .got
    136   OutputRelocSection* m_pRelDyn;        // .rel.dyn
    137 
    138   MipsELFDynamic* m_pDynamic;
    139   LDSymbol* m_pGOTSymbol;
    140   LDSymbol* m_pGpDispSymbol;
    141 
    142   SymbolListType m_GlobalGOTSyms;
    143 };
    144 
    145 } // namespace of mcld
    146 
    147 #endif
    148 
    149