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"
16 #include "llvm/ADT/CachedHashString.h"
17 #include "llvm/ADT/DenseMap.h"
22 class OutputSectionBase;
25 // SymbolTable is a bucket of all known symbols, including defined,
26 // undefined, or lazy symbols (the last one is symbols in archive
27 // files whose archive members are not yet loaded).
29 // We put all symbols of all files to a SymbolTable, and the
30 // SymbolTable selects the "best" symbols if there are name
31 // conflicts. For example, obviously, a defined symbol is better than
32 // an undefined symbol. Or, if there's a conflict between a lazy and a
33 // undefined, it'll read an archive member to read a real definition
34 // to replace the lazy symbol. The logic is implemented in the
35 // add*() functions, which are called by input files as they are parsed. There
36 // is one add* function per symbol type.
37 template <class ELFT> class SymbolTable {
38 typedef typename ELFT::Sym Elf_Sym;
39 typedef typename ELFT::uint uintX_t;
42 void addFile(InputFile *File);
43 void addCombinedLTOObject();
45 ArrayRef<Symbol *> getSymbols() const { return SymVector; }
46 ArrayRef<ObjectFile<ELFT> *> getObjectFiles() const { return ObjectFiles; }
47 ArrayRef<BinaryFile *> getBinaryFiles() const { return BinaryFiles; }
48 ArrayRef<SharedFile<ELFT> *> getSharedFiles() const { return SharedFiles; }
50 DefinedRegular<ELFT> *addAbsolute(StringRef Name,
51 uint8_t Visibility = llvm::ELF::STV_HIDDEN,
52 uint8_t Binding = llvm::ELF::STB_GLOBAL);
53 DefinedRegular<ELFT> *addIgnored(StringRef Name,
54 uint8_t Visibility = llvm::ELF::STV_HIDDEN);
56 Symbol *addUndefined(StringRef Name);
57 Symbol *addUndefined(StringRef Name, bool IsLocal, uint8_t Binding,
58 uint8_t StOther, uint8_t Type, bool CanOmitFromDynSym,
61 Symbol *addRegular(StringRef Name, uint8_t StOther, uint8_t Type,
62 uintX_t Value, uintX_t Size, uint8_t Binding,
63 InputSectionBase<ELFT> *Section, InputFile *File);
65 Symbol *addSynthetic(StringRef N, const OutputSectionBase *Section,
66 uintX_t Value, uint8_t StOther);
68 void addShared(SharedFile<ELFT> *F, StringRef Name, const Elf_Sym &Sym,
69 const typename ELFT::Verdef *Verdef);
71 void addLazyArchive(ArchiveFile *F, const llvm::object::Archive::Symbol S);
72 void addLazyObject(StringRef Name, LazyObjectFile &Obj);
73 Symbol *addBitcode(StringRef Name, uint8_t Binding, uint8_t StOther,
74 uint8_t Type, bool CanOmitFromDynSym, BitcodeFile *File);
76 Symbol *addCommon(StringRef N, uint64_t Size, uint64_t Alignment,
77 uint8_t Binding, uint8_t StOther, uint8_t Type,
80 void scanUndefinedFlags();
81 void scanShlibUndefined();
82 void scanVersionScript();
84 SymbolBody *find(StringRef Name);
85 SymbolBody *findInCurrentDSO(StringRef Name);
87 void trace(StringRef Name);
88 void wrap(StringRef Name);
90 std::vector<InputSectionBase<ELFT> *> Sections;
93 std::pair<Symbol *, bool> insert(StringRef Name);
94 std::pair<Symbol *, bool> insert(StringRef Name, uint8_t Type,
95 uint8_t Visibility, bool CanOmitFromDynSym,
98 std::vector<SymbolBody *> findByVersion(SymbolVersion Ver);
99 std::vector<SymbolBody *> findAllByVersion(SymbolVersion Ver);
101 llvm::StringMap<std::vector<SymbolBody *>> &getDemangledSyms();
102 void handleAnonymousVersion();
103 void assignExactVersion(SymbolVersion Ver, uint16_t VersionId,
104 StringRef VersionName);
105 void assignWildcardVersion(SymbolVersion Ver, uint16_t VersionId);
108 SymIndex(int Idx, bool Traced) : Idx(Idx), Traced(Traced) {}
113 // The order the global symbols are in is not defined. We can use an arbitrary
114 // order, but it has to be reproducible. That is true even when cross linking.
115 // The default hashing of StringRef produces different results on 32 and 64
116 // bit systems so we use a map to a vector. That is arbitrary, deterministic
117 // but a bit inefficient.
118 // FIXME: Experiment with passing in a custom hashing or sorting the symbols
119 // once symbol resolution is finished.
120 llvm::DenseMap<llvm::CachedHashStringRef, SymIndex> Symtab;
121 std::vector<Symbol *> SymVector;
123 // Comdat groups define "link once" sections. If two comdat groups have the
124 // same name, only one of them is linked, and the other is ignored. This set
125 // is used to uniquify them.
126 llvm::DenseSet<llvm::CachedHashStringRef> ComdatGroups;
128 std::vector<ObjectFile<ELFT> *> ObjectFiles;
129 std::vector<SharedFile<ELFT> *> SharedFiles;
130 std::vector<BitcodeFile *> BitcodeFiles;
131 std::vector<BinaryFile *> BinaryFiles;
133 // Set of .so files to not link the same shared object file more than once.
134 llvm::DenseSet<StringRef> SoNames;
136 // A map from demangled symbol names to their symbol objects.
137 // This mapping is 1:N because two symbols with different versions
138 // can have the same name. We use this map to handle "extern C++ {}"
139 // directive in version scripts.
140 llvm::Optional<llvm::StringMap<std::vector<SymbolBody *>>> DemangledSyms;
143 std::unique_ptr<BitcodeCompiler> LTO;
146 template <class ELFT> struct Symtab { static SymbolTable<ELFT> *X; };
147 template <class ELFT> SymbolTable<ELFT> *Symtab<ELFT>::X;