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 template <class ELFT> void addSymbolWrap(StringRef Name);
41 void applySymbolWrap();
43 ArrayRef<Symbol *> getSymbols() const { return SymVector; }
45 Defined *addAbsolute(StringRef Name,
46 uint8_t Visibility = llvm::ELF::STV_HIDDEN,
47 uint8_t Binding = llvm::ELF::STB_GLOBAL);
49 template <class ELFT> Symbol *addUndefined(StringRef Name);
51 Symbol *addUndefined(StringRef Name, uint8_t Binding, uint8_t StOther,
52 uint8_t Type, bool CanOmitFromDynSym, InputFile *File);
53 Symbol *addRegular(StringRef Name, uint8_t StOther, uint8_t Type,
54 uint64_t Value, uint64_t Size, uint8_t Binding,
55 SectionBase *Section, InputFile *File);
58 void addShared(StringRef Name, SharedFile<ELFT> &F,
59 const typename ELFT::Sym &Sym, uint32_t Alignment,
60 uint32_t VerdefIndex);
63 void addLazyArchive(StringRef Name, ArchiveFile &F,
64 const llvm::object::Archive::Symbol S);
66 template <class ELFT> void addLazyObject(StringRef Name, LazyObjFile &Obj);
68 Symbol *addBitcode(StringRef Name, uint8_t Binding, uint8_t StOther,
69 uint8_t Type, bool CanOmitFromDynSym, BitcodeFile &File);
71 Symbol *addCommon(StringRef Name, uint64_t Size, uint32_t Alignment,
72 uint8_t Binding, uint8_t StOther, uint8_t Type,
75 std::pair<Symbol *, bool> insert(StringRef Name);
76 std::pair<Symbol *, bool> insert(StringRef Name, uint8_t Type,
77 uint8_t Visibility, bool CanOmitFromDynSym,
80 template <class ELFT> void fetchLazy(Symbol *Sym);
82 void scanVersionScript();
84 Symbol *find(StringRef Name);
86 void trace(StringRef Name);
88 void handleDynamicList();
91 std::vector<Symbol *> findByVersion(SymbolVersion Ver);
92 std::vector<Symbol *> findAllByVersion(SymbolVersion Ver);
94 llvm::StringMap<std::vector<Symbol *>> &getDemangledSyms();
95 void handleAnonymousVersion();
96 void assignExactVersion(SymbolVersion Ver, uint16_t VersionId,
97 StringRef VersionName);
98 void assignWildcardVersion(SymbolVersion Ver, uint16_t VersionId);
100 // The order the global symbols are in is not defined. We can use an arbitrary
101 // order, but it has to be reproducible. That is true even when cross linking.
102 // The default hashing of StringRef produces different results on 32 and 64
103 // bit systems so we use a map to a vector. That is arbitrary, deterministic
104 // but a bit inefficient.
105 // FIXME: Experiment with passing in a custom hashing or sorting the symbols
106 // once symbol resolution is finished.
107 llvm::DenseMap<llvm::CachedHashStringRef, int> SymMap;
108 std::vector<Symbol *> SymVector;
110 // Comdat groups define "link once" sections. If two comdat groups have the
111 // same name, only one of them is linked, and the other is ignored. This set
112 // is used to uniquify them.
113 llvm::DenseSet<llvm::CachedHashStringRef> ComdatGroups;
115 // Set of .so files to not link the same shared object file more than once.
116 llvm::DenseSet<StringRef> SoNames;
118 // A map from demangled symbol names to their symbol objects.
119 // This mapping is 1:N because two symbols with different versions
120 // can have the same name. We use this map to handle "extern C++ {}"
121 // directive in version scripts.
122 llvm::Optional<llvm::StringMap<std::vector<Symbol *>>> DemangledSyms;
124 struct WrappedSymbol {
131 std::vector<WrappedSymbol> WrappedSymbols;
134 std::unique_ptr<BitcodeCompiler> LTO;
137 extern SymbolTable *Symtab;