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      1 //===- IdenticalCodeFolding.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_IDENTICALCODEFOLDING_H_
     10 #define MCLD_LD_IDENTICALCODEFOLDING_H_
     11 
     12 #include <llvm/ADT/MapVector.h>
     13 
     14 #include <string>
     15 #include <vector>
     16 
     17 namespace mcld {
     18 
     19 class Input;
     20 class LDSection;
     21 class LinkerConfig;
     22 class Module;
     23 class Relocation;
     24 class TargetLDBackend;
     25 
     26 /** \class IdenticalCodeFolding
     27  *  \brief Implementation of identical code folding for --icf=[none|all|safe]
     28  *  @ref Safe ICF: Pointer Safe and Unwinding Aware Identical Code Folding in
     29  *       Gold, http://research.google.com/pubs/pub36912.html
     30  */
     31 class IdenticalCodeFolding {
     32  public:
     33   typedef std::pair<Input*, size_t> ObjectAndId;
     34   typedef llvm::MapVector<LDSection*, ObjectAndId> KeptSections;
     35 
     36  private:
     37   class FoldingCandidate {
     38    public:
     39     FoldingCandidate() : sect(NULL), reloc_sect(NULL), obj(NULL) {}
     40     FoldingCandidate(LDSection* pCode, LDSection* pReloc, Input* pInput)
     41         : sect(pCode), reloc_sect(pReloc), obj(pInput) {}
     42 
     43     void initConstantContent(
     44         const TargetLDBackend& pBackend,
     45         const IdenticalCodeFolding::KeptSections& pKeptSections);
     46     std::string getContentWithVariables(
     47         const TargetLDBackend& pBackend,
     48         const IdenticalCodeFolding::KeptSections& pKeptSections);
     49 
     50     LDSection* sect;
     51     LDSection* reloc_sect;
     52     Input* obj;
     53     std::string content;
     54     std::vector<Relocation*> variable_relocs;
     55   };
     56 
     57   typedef std::vector<FoldingCandidate> FoldingCandidates;
     58 
     59  public:
     60   IdenticalCodeFolding(const LinkerConfig& pConfig,
     61                        const TargetLDBackend& pBackend,
     62                        Module& pModule);
     63 
     64   void foldIdenticalCode();
     65 
     66  private:
     67   void findCandidates(FoldingCandidates& pCandidateList);
     68 
     69   bool matchCandidates(FoldingCandidates& pCandidateList);
     70 
     71  private:
     72   const LinkerConfig& m_Config;
     73   const TargetLDBackend& m_Backend;
     74   Module& m_Module;
     75   KeptSections m_KeptSections;
     76 };
     77 
     78 }  // namespace mcld
     79 
     80 #endif  // MCLD_LD_IDENTICALCODEFOLDING_H_
     81