1 //===- SymbolTable.h --------------------------------------------*- C++ -*-===//
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLD_ELF_SYMBOL_TABLE_H
11 #define LLD_ELF_SYMBOL_TABLE_H
13 #include "InputFiles.h"
15 #include "lld/Common/Strings.h"
16 #include "llvm/ADT/CachedHashString.h"
17 #include "llvm/ADT/DenseMap.h"
24 // SymbolTable is a bucket of all known symbols, including defined,
25 // undefined, or lazy symbols (the last one is symbols in archive
26 // files whose archive members are not yet loaded).
28 // We put all symbols of all files to a SymbolTable, and the
29 // SymbolTable selects the "best" symbols if there are name
30 // conflicts. For example, obviously, a defined symbol is better than
31 // an undefined symbol. Or, if there's a conflict between a lazy and a
32 // undefined, it'll read an archive member to read a real definition
33 // to replace the lazy symbol. The logic is implemented in the
34 // add*() functions, which are called by input files as they are parsed. There
35 // is one add* function per symbol type.
38 template <class ELFT> void addFile(InputFile *File);
39 template <class ELFT> void addCombinedLTOObject();
40 void wrap(Symbol *Sym, Symbol *Real, Symbol *Wrap);
42 ArrayRef<Symbol *> getSymbols() const { return SymVector; }
45 Symbol *addUndefined(StringRef Name, uint8_t Binding, uint8_t StOther,
46 uint8_t Type, bool CanOmitFromDynSym, InputFile *File);
48 Defined *addDefined(StringRef Name, uint8_t StOther, uint8_t Type,
49 uint64_t Value, uint64_t Size, uint8_t Binding,
50 SectionBase *Section, InputFile *File);
53 void addShared(StringRef Name, SharedFile<ELFT> &F,
54 const typename ELFT::Sym &Sym, uint32_t Alignment,
55 uint32_t VerdefIndex);
58 void addLazyArchive(StringRef Name, ArchiveFile &F,
59 const llvm::object::Archive::Symbol S);
61 template <class ELFT> void addLazyObject(StringRef Name, LazyObjFile &Obj);
63 Symbol *addBitcode(StringRef Name, uint8_t Binding, uint8_t StOther,
64 uint8_t Type, bool CanOmitFromDynSym, BitcodeFile &File);
66 Symbol *addCommon(StringRef Name, uint64_t Size, uint32_t Alignment,
67 uint8_t Binding, uint8_t StOther, uint8_t Type,
70 std::pair<Symbol *, bool> insert(StringRef Name, uint8_t Visibility,
71 bool CanOmitFromDynSym, InputFile *File);
73 template <class ELFT> void fetchLazy(Symbol *Sym);
75 void scanVersionScript();
77 Symbol *find(StringRef Name);
79 void trace(StringRef Name);
81 void handleDynamicList();
83 // Set of .so files to not link the same shared object file more than once.
84 llvm::DenseMap<StringRef, InputFile *> SoNames;
87 std::pair<Symbol *, bool> insertName(StringRef Name);
89 std::vector<Symbol *> findByVersion(SymbolVersion Ver);
90 std::vector<Symbol *> findAllByVersion(SymbolVersion Ver);
92 llvm::StringMap<std::vector<Symbol *>> &getDemangledSyms();
93 void assignExactVersion(SymbolVersion Ver, uint16_t VersionId,
94 StringRef VersionName);
95 void assignWildcardVersion(SymbolVersion Ver, uint16_t VersionId);
97 // The order the global symbols are in is not defined. We can use an arbitrary
98 // order, but it has to be reproducible. That is true even when cross linking.
99 // The default hashing of StringRef produces different results on 32 and 64
100 // bit systems so we use a map to a vector. That is arbitrary, deterministic
101 // but a bit inefficient.
102 // FIXME: Experiment with passing in a custom hashing or sorting the symbols
103 // once symbol resolution is finished.
104 llvm::DenseMap<llvm::CachedHashStringRef, int> SymMap;
105 std::vector<Symbol *> SymVector;
107 // Comdat groups define "link once" sections. If two comdat groups have the
108 // same name, only one of them is linked, and the other is ignored. This set
109 // is used to uniquify them.
110 llvm::DenseSet<llvm::CachedHashStringRef> ComdatGroups;
112 // A map from demangled symbol names to their symbol objects.
113 // This mapping is 1:N because two symbols with different versions
114 // can have the same name. We use this map to handle "extern C++ {}"
115 // directive in version scripts.
116 llvm::Optional<llvm::StringMap<std::vector<Symbol *>>> DemangledSyms;
119 std::unique_ptr<BitcodeCompiler> LTO;
122 extern SymbolTable *Symtab;