1//===- SymbolTable.h --------------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLD_COFF_SYMBOL_TABLE_H
10#define LLD_COFF_SYMBOL_TABLE_H
11
12#include "InputFiles.h"
13#include "LTO.h"
14#include "llvm/ADT/CachedHashString.h"
15#include "llvm/ADT/DenseMap.h"
16#include "llvm/ADT/DenseMapInfo.h"
17#include "llvm/Support/raw_ostream.h"
18
19namespace llvm {
20struct LTOCodeGenerator;
21}
22
23namespace lld::coff {
24
25class Chunk;
26class CommonChunk;
27class COFFLinkerContext;
28class Defined;
29class DefinedAbsolute;
30class DefinedRegular;
31class DefinedRelative;
32class LazyArchive;
33class SectionChunk;
34class Symbol;
35
36// SymbolTable is a bucket of all known symbols, including defined,
37// undefined, or lazy symbols (the last one is symbols in archive
38// files whose archive members are not yet loaded).
39//
40// We put all symbols of all files to a SymbolTable, and the
41// SymbolTable selects the "best" symbols if there are name
42// conflicts. For example, obviously, a defined symbol is better than
43// an undefined symbol. Or, if there's a conflict between a lazy and a
44// undefined, it'll read an archive member to read a real definition
45// to replace the lazy symbol. The logic is implemented in the
46// add*() functions, which are called by input files as they are parsed.
47// There is one add* function per symbol type.
48class SymbolTable {
49public:
50 SymbolTable(COFFLinkerContext &c) : ctx(c) {}
51
52 void addFile(InputFile *file);
53
54 // Emit errors for symbols that cannot be resolved.
55 void reportUnresolvable();
56
57 // Try to resolve any undefined symbols and update the symbol table
58 // accordingly, then print an error message for any remaining undefined
59 // symbols and warn about imported local symbols.
60 void resolveRemainingUndefines();
61
62 // Load lazy objects that are needed for MinGW automatic import and for
63 // doing stdcall fixups.
64 void loadMinGWSymbols();
65 bool handleMinGWAutomaticImport(Symbol *sym, StringRef name);
66
67 // Returns a list of chunks of selected symbols.
68 std::vector<Chunk *> getChunks() const;
69
70 // Returns a symbol for a given name. Returns a nullptr if not found.
71 Symbol *find(StringRef name) const;
72 Symbol *findUnderscore(StringRef name) const;
73
74 // Occasionally we have to resolve an undefined symbol to its
75 // mangled symbol. This function tries to find a mangled name
76 // for U from the symbol table, and if found, set the symbol as
77 // a weak alias for U.
78 Symbol *findMangle(StringRef name);
79
80 // Build a set of COFF objects representing the combined contents of
81 // BitcodeFiles and add them to the symbol table. Called after all files are
82 // added and before the writer writes results to a file.
83 void compileBitcodeFiles();
84
85 // Creates an Undefined symbol for a given name.
86 Symbol *addUndefined(StringRef name);
87
88 Symbol *addSynthetic(StringRef n, Chunk *c);
89 Symbol *addAbsolute(StringRef n, uint64_t va);
90
91 Symbol *addUndefined(StringRef name, InputFile *f, bool isWeakAlias);
92 void addLazyArchive(ArchiveFile *f, const Archive::Symbol &sym);
93 void addLazyObject(InputFile *f, StringRef n);
94 void addLazyDLLSymbol(DLLFile *f, DLLFile::Symbol *sym, StringRef n);
95 Symbol *addAbsolute(StringRef n, COFFSymbolRef s);
96 Symbol *addRegular(InputFile *f, StringRef n,
97 const llvm::object::coff_symbol_generic *s = nullptr,
98 SectionChunk *c = nullptr, uint32_t sectionOffset = 0,
99 bool isWeak = false);
100 std::pair<DefinedRegular *, bool>
101 addComdat(InputFile *f, StringRef n,
102 const llvm::object::coff_symbol_generic *s = nullptr);
103 Symbol *addCommon(InputFile *f, StringRef n, uint64_t size,
104 const llvm::object::coff_symbol_generic *s = nullptr,
105 CommonChunk *c = nullptr);
106 Symbol *addImportData(StringRef n, ImportFile *f);
107 Symbol *addImportThunk(StringRef name, DefinedImportData *s,
108 uint16_t machine);
109 void addLibcall(StringRef name);
110
111 void reportDuplicate(Symbol *existing, InputFile *newFile,
112 SectionChunk *newSc = nullptr,
113 uint32_t newSectionOffset = 0);
114
115 // A list of chunks which to be added to .rdata.
116 std::vector<Chunk *> localImportChunks;
117
118 // Iterates symbols in non-determinstic hash table order.
119 template <typename T> void forEachSymbol(T callback) {
120 for (auto &pair : symMap)
121 callback(pair.second);
122 }
123
124private:
125 /// Given a name without "__imp_" prefix, returns a defined symbol
126 /// with the "__imp_" prefix, if it exists.
127 Defined *impSymbol(StringRef name);
128 /// Inserts symbol if not already present.
129 std::pair<Symbol *, bool> insert(StringRef name);
130 /// Same as insert(Name), but also sets isUsedInRegularObj.
131 std::pair<Symbol *, bool> insert(StringRef name, InputFile *f);
132
133 std::vector<Symbol *> getSymsWithPrefix(StringRef prefix);
134
135 llvm::DenseMap<llvm::CachedHashStringRef, Symbol *> symMap;
136 std::unique_ptr<BitcodeCompiler> lto;
137
138 COFFLinkerContext &ctx;
139};
140
141std::vector<std::string> getSymbolLocations(ObjFile *file, uint32_t symIndex);
142
143StringRef ltrim1(StringRef s, const char *chars);
144
145} // namespace lld::coff
146
147#endif
148

source code of lld/COFF/SymbolTable.h