146 lines
		
	
	
		
			5.4 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			146 lines
		
	
	
		
			5.4 KiB
		
	
	
	
		
			C++
		
	
	
	
//===- SymbolTable.h --------------------------------------------*- C++ -*-===//
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//
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//                             The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLD_ELF_SYMBOL_TABLE_H
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#define LLD_ELF_SYMBOL_TABLE_H
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#include "InputFiles.h"
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#include "LTO.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/Support/Regex.h"
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namespace lld {
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namespace elf {
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class Lazy;
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template <class ELFT> class OutputSectionBase;
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struct Symbol;
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typedef llvm::CachedHash<StringRef> SymName;
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// SymbolTable is a bucket of all known symbols, including defined,
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// undefined, or lazy symbols (the last one is symbols in archive
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// files whose archive members are not yet loaded).
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//
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// We put all symbols of all files to a SymbolTable, and the
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// SymbolTable selects the "best" symbols if there are name
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// conflicts. For example, obviously, a defined symbol is better than
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// an undefined symbol. Or, if there's a conflict between a lazy and a
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// undefined, it'll read an archive member to read a real definition
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// to replace the lazy symbol. The logic is implemented in the
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// add*() functions, which are called by input files as they are parsed. There
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// is one add* function per symbol type.
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template <class ELFT> class SymbolTable {
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  typedef typename ELFT::Sym Elf_Sym;
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  typedef typename ELFT::uint uintX_t;
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public:
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  void addFile(InputFile *File);
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  void addCombinedLtoObject();
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  llvm::ArrayRef<Symbol *> getSymbols() const { return SymVector; }
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  const std::vector<ObjectFile<ELFT> *> &getObjectFiles() const {
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    return ObjectFiles;
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  }
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  const std::vector<SharedFile<ELFT> *> &getSharedFiles() const {
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    return SharedFiles;
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  }
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  DefinedRegular<ELFT> *addAbsolute(StringRef Name,
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                                    uint8_t Visibility = llvm::ELF::STV_HIDDEN);
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  DefinedRegular<ELFT> *addIgnored(StringRef Name,
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                                   uint8_t Visibility = llvm::ELF::STV_HIDDEN);
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  Symbol *addUndefined(StringRef Name);
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  Symbol *addUndefined(StringRef Name, uint8_t Binding, uint8_t StOther,
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                       uint8_t Type, bool CanOmitFromDynSym,
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                       bool HasUnnamedAddr, InputFile *File);
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  Symbol *addRegular(StringRef Name, const Elf_Sym &Sym,
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                     InputSectionBase<ELFT> *Section);
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  Symbol *addRegular(StringRef Name, uint8_t Binding, uint8_t StOther);
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  Symbol *addSynthetic(StringRef N, OutputSectionBase<ELFT> *Section,
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                       uintX_t Value, uint8_t StOther);
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  void addShared(SharedFile<ELFT> *F, StringRef Name, const Elf_Sym &Sym,
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                 const typename ELFT::Verdef *Verdef);
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  void addLazyArchive(ArchiveFile *F, const llvm::object::Archive::Symbol S);
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  void addLazyObject(StringRef Name, LazyObjectFile &Obj);
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  Symbol *addBitcode(StringRef Name, uint8_t Binding, uint8_t StOther,
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                     uint8_t Type, bool CanOmitFromDynSym, bool HasUnnamedAddr,
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                     BitcodeFile *File);
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  Symbol *addCommon(StringRef N, uint64_t Size, uint64_t Alignment,
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                    uint8_t Binding, uint8_t StOther, uint8_t Type,
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                    bool HasUnnamedAddr, InputFile *File);
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  void scanUndefinedFlags();
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  void scanShlibUndefined();
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  void scanDynamicList();
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  void scanVersionScript();
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  SymbolBody *find(StringRef Name);
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  void trace(StringRef Name);
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  void wrap(StringRef Name);
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private:
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  std::vector<SymbolBody *> findAll(const llvm::Regex &Re);
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  std::pair<Symbol *, bool> insert(StringRef &Name);
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  std::pair<Symbol *, bool> insert(StringRef &Name, uint8_t Type,
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                                   uint8_t Visibility, bool CanOmitFromDynSym,
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                                   bool HasUnnamedAddr, InputFile *File);
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  std::string conflictMsg(SymbolBody *Existing, InputFile *NewFile);
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  void reportDuplicate(SymbolBody *Existing, InputFile *NewFile);
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  std::map<std::string, std::vector<SymbolBody *>> getDemangledSyms();
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  void handleAnonymousVersion();
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  struct SymIndex {
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    SymIndex(int Idx, bool Traced) : Idx(Idx), Traced(Traced) {}
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    int Idx : 31;
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    unsigned Traced : 1;
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  };
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  // The order the global symbols are in is not defined. We can use an arbitrary
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  // order, but it has to be reproducible. That is true even when cross linking.
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  // The default hashing of StringRef produces different results on 32 and 64
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  // bit systems so we use a map to a vector. That is arbitrary, deterministic
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  // but a bit inefficient.
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  // FIXME: Experiment with passing in a custom hashing or sorting the symbols
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  // once symbol resolution is finished.
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  llvm::DenseMap<SymName, SymIndex> Symtab;
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  std::vector<Symbol *> SymVector;
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  llvm::BumpPtrAllocator Alloc;
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  // Comdat groups define "link once" sections. If two comdat groups have the
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  // same name, only one of them is linked, and the other is ignored. This set
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  // is used to uniquify them.
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  llvm::DenseSet<StringRef> ComdatGroups;
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  std::vector<ObjectFile<ELFT> *> ObjectFiles;
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  std::vector<SharedFile<ELFT> *> SharedFiles;
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  std::vector<BitcodeFile *> BitcodeFiles;
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  // Set of .so files to not link the same shared object file more than once.
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  llvm::DenseSet<StringRef> SoNames;
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  std::unique_ptr<BitcodeCompiler> Lto;
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};
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template <class ELFT> struct Symtab { static SymbolTable<ELFT> *X; };
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template <class ELFT> SymbolTable<ELFT> *Symtab<ELFT>::X;
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} // namespace elf
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} // namespace lld
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#endif
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