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      1 //===-- llvm/Target/TargetLDBackend.h - Target LD Backend -----*- C++ -*-===//
      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 LLVM_TARGET_TARGETLDBACKEND_H
     10 #define LLVM_TARGET_TARGETLDBACKEND_H
     11 
     12 #include <llvm/Support/DataTypes.h>
     13 #include <mcld/MC/MCLDOutput.h>
     14 
     15 namespace mcld {
     16 
     17 class MCLinker;
     18 class Relocation;
     19 class RelocationFactory;
     20 class Layout;
     21 class ArchiveReader;
     22 class ObjectReader;
     23 class DynObjReader;
     24 class ObjectWriter;
     25 class DynObjWriter;
     26 class LDContext;
     27 class SectionMap;
     28 class Output;
     29 class MCLDInfo;
     30 class SymbolCategory;
     31 class Input;
     32 class LDFileFormat;
     33 class GOT;
     34 
     35 //===----------------------------------------------------------------------===//
     36 /// TargetLDBackend - Generic interface to target specific assembler backends.
     37 ///
     38 class TargetLDBackend
     39 {
     40   TargetLDBackend(const TargetLDBackend &);   // DO NOT IMPLEMENT
     41   void operator=(const TargetLDBackend &);  // DO NOT IMPLEMENT
     42 
     43 protected:
     44   TargetLDBackend();
     45 
     46 public:
     47   virtual ~TargetLDBackend();
     48 
     49   // -----  target dependent  ----- //
     50   virtual bool initTargetSectionMap(SectionMap& pSectionMap) { return true;}
     51   virtual void initTargetSegments(MCLinker& pLinker) { }
     52   virtual void initTargetSections(MCLinker& pLinker) { }
     53   virtual void initTargetSymbols(MCLinker& pLinker) { }
     54   virtual void initTargetRelocation(MCLinker& pLinker) { }
     55   virtual bool initStandardSymbols(MCLinker& pLinker) = 0;
     56   virtual bool initRelocFactory(const MCLinker& pLinker) = 0;
     57 
     58   virtual RelocationFactory* getRelocFactory() = 0;
     59 
     60   /// scanRelocation - When read in relocations, backend can do any modification
     61   /// to relocation and generate empty entries, such as GOT, dynamic relocation
     62   /// entries and other target dependent entries. These entries are generated
     63   /// for layout to adjust the ouput offset.
     64   /// @param pReloc - a read in relocation entry
     65   /// @param pInputSym - the input LDSymbol of relocation target symbol
     66   /// @param pOutput - the ouput file
     67   virtual void scanRelocation(Relocation& pReloc,
     68                               const LDSymbol& pInputSym,
     69                               MCLinker& pLinker,
     70                               const MCLDInfo& pLDInfo,
     71                               const Output& pOutput) = 0;
     72 
     73   // -----  format dependent  ----- //
     74   virtual bool initArchiveReader(MCLinker&, MCLDInfo&) = 0;
     75   virtual bool initObjectReader(MCLinker&) = 0;
     76   virtual bool initDynObjReader(MCLinker&) = 0;
     77   virtual bool initObjectWriter(MCLinker&) = 0;
     78   virtual bool initDynObjWriter(MCLinker&) = 0;
     79 
     80   virtual bool initExecSections(MCLinker&) = 0;
     81   virtual bool initDynObjSections(MCLinker&) = 0;
     82 
     83   virtual ArchiveReader *getArchiveReader() = 0;
     84   virtual ObjectReader *getObjectReader() = 0;
     85   virtual DynObjReader *getDynObjReader() = 0;
     86   virtual ObjectWriter *getObjectWriter() = 0;
     87   virtual DynObjWriter *getDynObjWriter() = 0;
     88 
     89   virtual LDFileFormat* getDynObjFileFormat() = 0;
     90   virtual LDFileFormat* getExecFileFormat() = 0;
     91 
     92   /// preLayout - Backend can do any needed modification before layout
     93   virtual void preLayout(const Output& pOutput,
     94                          const MCLDInfo& pInfo,
     95                          MCLinker& pLinker) = 0;
     96 
     97   /// postLayout -Backend can do any needed modification after layout
     98   virtual void postLayout(const Output& pOutput,
     99                           const MCLDInfo& pInfo,
    100                           MCLinker& pLinker) = 0;
    101 
    102   /// Is the target machine little endian? **/
    103   virtual bool isLittleEndian() const = 0;
    104 
    105   /// bit class. the bit length of the target machine, 32 or 64 **/
    106   virtual unsigned int bitclass() const = 0;
    107 
    108   /// the page size of the target machine
    109   virtual unsigned int pagesize() const = 0;
    110 
    111   /// section start offset in the output file
    112   virtual size_t sectionStartOffset() const = 0;
    113 
    114   /// computeSectionOrder - compute the layout order of the given section
    115   virtual unsigned int getSectionOrder(const Output& pOutput,
    116                                        const LDSection& pSectHdr) const = 0;
    117 
    118   /// sizeNamePools - compute the size of regular name pools
    119   /// In ELF executable files, regular name pools are .symtab, .strtab.,
    120   /// .dynsym, .dynstr, and .hash
    121   virtual void
    122   sizeNamePools(const Output& pOutput,
    123                 const SymbolCategory& pSymbols,
    124                 const MCLDInfo& pLDInfo) = 0;
    125 
    126   /// finalizeSymbol - Linker checks pSymbol.reserved() if it's not zero,
    127   /// then it will ask backend to finalize the symbol value.
    128   /// @return ture - if backend set the symbol value sucessfully
    129   /// @return false - if backend do not recognize the symbol
    130   virtual bool finalizeSymbol(LDSymbol& pSymbol) const = 0;
    131 
    132   /// allocateCommonSymbols - allocate common symbols in the corresponding
    133   /// sections.
    134   virtual bool allocateCommonSymbols(const MCLDInfo& pLDInfo, MCLinker& pLinker) const = 0;
    135 
    136   /// readSection - read a target dependent section
    137   virtual bool readSection(Input& pInput,
    138                            MCLinker& pLinker,
    139                            LDSection& pInputSectHdr)
    140   { return true; }
    141 
    142 };
    143 
    144 } // End mcld namespace
    145 
    146 #endif
    147