Home | History | Annotate | Download | only in LD 
      1 //===- BranchIsland.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_BRANCHISLAND_H_
     10 #define MCLD_LD_BRANCHISLAND_H_
     11 
     12 #include "mcld/ADT/HashEntry.h"
     13 #include "mcld/ADT/HashTable.h"
     14 #include "mcld/ADT/StringHash.h"
     15 #include "mcld/LD/SectionData.h"
     16 #include "mcld/Fragment/FragmentRef.h"
     17 #include "mcld/Fragment/Stub.h"
     18 #include "mcld/LD/LDSymbol.h"
     19 
     20 #include <llvm/Support/DataTypes.h>
     21 #include <llvm/ADT/StringRef.h>
     22 
     23 #include <string>
     24 
     25 namespace mcld {
     26 
     27 class Relocation;
     28 class Stub;
     29 
     30 /** \class BranchIsland
     31  *  \brief BranchIsland is a collection of stubs
     32  *
     33  */
     34 class BranchIsland {
     35  public:
     36   typedef SectionData::iterator iterator;
     37   typedef SectionData::const_iterator const_iterator;
     38 
     39   typedef std::vector<Relocation*> RelocationListType;
     40   typedef RelocationListType::iterator reloc_iterator;
     41   typedef RelocationListType::const_iterator const_reloc_iterator;
     42 
     43  public:
     44   /*
     45    *               ----------
     46    *  --- Entry -> | Island | -> Exit ---
     47    *               ----------
     48    */
     49 
     50   /// BranchIsland - constructor
     51   /// @param pEntryFrag - the entry fragment to the island
     52   /// @param pMaxSize   - the max size the island can be
     53   /// @param pIndex     - the inedx in the island factory
     54   BranchIsland(Fragment& pEntryFrag, size_t pMaxSize, size_t pIndex);
     55 
     56   ~BranchIsland();
     57 
     58   /// fragment iterators of the island
     59   iterator begin();
     60 
     61   const_iterator begin() const;
     62 
     63   iterator end();
     64 
     65   const_iterator end() const;
     66 
     67   /// relocation iterators of the island
     68   reloc_iterator reloc_begin() { return m_Relocations.begin(); }
     69 
     70   const_reloc_iterator reloc_begin() const { return m_Relocations.begin(); }
     71 
     72   reloc_iterator reloc_end() { return m_Relocations.end(); }
     73 
     74   const_reloc_iterator reloc_end() const { return m_Relocations.end(); }
     75 
     76   /// observers
     77   uint64_t offset() const;
     78 
     79   size_t size() const;
     80 
     81   size_t maxSize() const;
     82 
     83   const std::string& name() const;
     84 
     85   size_t numOfStubs() const;
     86 
     87   /// findStub - return true if there is a stub built from the given prototype
     88   ///            for the given relocation
     89   Stub* findStub(const Stub* pPrototype, const Relocation& pReloc);
     90 
     91   /// addStub - add a stub into the island
     92   bool addStub(const Stub* pPrototype, const Relocation& pReloc, Stub& pStub);
     93 
     94   /// addRelocation - add a relocation into island
     95   bool addRelocation(Relocation& pReloc);
     96 
     97  private:
     98   /** \class Key
     99    *  \brief Key to recognize a stub in the island.
    100    *
    101    */
    102   class Key {
    103    public:
    104     Key(const Stub* pPrototype, const LDSymbol* pSymbol, Stub::SWord pAddend)
    105         : m_pPrototype(pPrototype), m_pSymbol(pSymbol), m_Addend(pAddend) {}
    106 
    107     ~Key() {}
    108 
    109     const Stub* prototype() const { return m_pPrototype; }
    110 
    111     const LDSymbol* symbol() const { return m_pSymbol; }
    112 
    113     Stub::SWord addend() const { return m_Addend; }
    114 
    115     struct Hash {
    116       size_t operator()(const Key& KEY) const {
    117         llvm::StringRef sym_name(KEY.symbol()->name());
    118         hash::StringHash<hash::DJB> str_hasher;
    119         return (size_t((uintptr_t)KEY.prototype())) ^ str_hasher(sym_name) ^
    120                KEY.addend();
    121       }
    122     };
    123 
    124     struct Compare {
    125       bool operator()(const Key& KEY1, const Key& KEY2) const {
    126         bool res = false;
    127         if ((KEY1.prototype() == KEY2.prototype()) &&
    128             (KEY1.addend() == KEY2.addend())) {
    129           if (KEY1.symbol() == KEY2.symbol()) {
    130             res = true;
    131           } else {
    132             // Folded symbols may use the existing stub.
    133             if (KEY1.symbol()->hasFragRef() && KEY2.symbol()->hasFragRef()) {
    134               const FragmentRef* ref1 = KEY1.symbol()->fragRef();
    135               const FragmentRef* ref2 = KEY2.symbol()->fragRef();
    136               if ((ref1->offset() == ref2->offset()) &&
    137                   (ref1->frag()->getOffset() == ref2->frag()->getOffset())) {
    138                 res = true;
    139               }
    140             }
    141           }
    142         }
    143         return res;
    144       }
    145     };
    146 
    147    private:
    148     const Stub* m_pPrototype;
    149     const LDSymbol* m_pSymbol;
    150     Stub::SWord m_Addend;
    151   };
    152 
    153   typedef HashEntry<Key, Stub*, Key::Compare> StubEntryType;
    154 
    155   typedef HashTable<StubEntryType, Key::Hash, EntryFactory<StubEntryType> >
    156       StubMapType;
    157 
    158  private:
    159   Fragment& m_Entry;  // entry fragment of the island
    160   Fragment* m_pExit;  // exit fragment of the island
    161   Fragment* m_pRear;  // rear fragment of the island
    162   size_t m_MaxSize;
    163   std::string m_Name;
    164   StubMapType m_StubMap;
    165   /// m_Relocations - list of relocations created for stubs in this island
    166   RelocationListType m_Relocations;
    167 };
    168 
    169 }  // namespace mcld
    170 
    171 #endif  // MCLD_LD_BRANCHISLAND_H_
    172