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 LazyArchive;
32class SectionChunk;
33class Symbol;
34
35// SymbolTable is a bucket of all known symbols, including defined,
36// undefined, or lazy symbols (the last one is symbols in archive
37// files whose archive members are not yet loaded).
38//
39// We put all symbols of all files to a SymbolTable, and the
40// SymbolTable selects the "best" symbols if there are name
41// conflicts. For example, obviously, a defined symbol is better than
42// an undefined symbol. Or, if there's a conflict between a lazy and a
43// undefined, it'll read an archive member to read a real definition
44// to replace the lazy symbol. The logic is implemented in the
45// add*() functions, which are called by input files as they are parsed.
46// There is one add* function per symbol type.
47class SymbolTable {
48public:
49 SymbolTable(COFFLinkerContext &c) : ctx(c) {}
50
51 void addFile(InputFile *file);
52
53 // Emit errors for symbols that cannot be resolved.
54 void reportUnresolvable();
55
56 // Try to resolve any undefined symbols and update the symbol table
57 // accordingly, then print an error message for any remaining undefined
58 // symbols and warn about imported local symbols.
59 void resolveRemainingUndefines();
60
61 // Load lazy objects that are needed for MinGW automatic import and for
62 // doing stdcall fixups.
63 void loadMinGWSymbols();
64 bool handleMinGWAutomaticImport(Symbol *sym, StringRef name);
65
66 // Returns a list of chunks of selected symbols.
67 std::vector<Chunk *> getChunks() const;
68
69 // Returns a symbol for a given name. Returns a nullptr if not found.
70 Symbol *find(StringRef name) const;
71 Symbol *findUnderscore(StringRef name) const;
72
73 // Occasionally we have to resolve an undefined symbol to its
74 // mangled symbol. This function tries to find a mangled name
75 // for U from the symbol table, and if found, set the symbol as
76 // a weak alias for U.
77 Symbol *findMangle(StringRef name);
78
79 // Build a set of COFF objects representing the combined contents of
80 // BitcodeFiles and add them to the symbol table. Called after all files are
81 // added and before the writer writes results to a file.
82 void compileBitcodeFiles();
83
84 // Creates an Undefined symbol for a given name.
85 Symbol *addUndefined(StringRef name);
86
87 Symbol *addSynthetic(StringRef n, Chunk *c);
88 Symbol *addAbsolute(StringRef n, uint64_t va);
89
90 Symbol *addUndefined(StringRef name, InputFile *f, bool isWeakAlias);
91 void addLazyArchive(ArchiveFile *f, const Archive::Symbol &sym);
92 void addLazyObject(InputFile *f, StringRef n);
93 void addLazyDLLSymbol(DLLFile *f, DLLFile::Symbol *sym, StringRef n);
94 Symbol *addAbsolute(StringRef n, COFFSymbolRef s);
95 Symbol *addRegular(InputFile *f, StringRef n,
96 const llvm::object::coff_symbol_generic *s = nullptr,
97 SectionChunk *c = nullptr, uint32_t sectionOffset = 0,
98 bool isWeak = false);
99 std::pair<DefinedRegular *, bool>
100 addComdat(InputFile *f, StringRef n,
101 const llvm::object::coff_symbol_generic *s = nullptr);
102 Symbol *addCommon(InputFile *f, StringRef n, uint64_t size,
103 const llvm::object::coff_symbol_generic *s = nullptr,
104 CommonChunk *c = nullptr);
105 Symbol *addImportData(StringRef n, ImportFile *f);
106 Symbol *addImportThunk(StringRef name, DefinedImportData *s,
107 uint16_t machine);
108 void addLibcall(StringRef name);
109
110 void reportDuplicate(Symbol *existing, InputFile *newFile,
111 SectionChunk *newSc = nullptr,
112 uint32_t newSectionOffset = 0);
113
114 // A list of chunks which to be added to .rdata.
115 std::vector<Chunk *> localImportChunks;
116
117 // Iterates symbols in non-determinstic hash table order.
118 template <typename T> void forEachSymbol(T callback) {
119 for (auto &pair : symMap)
120 callback(pair.second);
121 }
122
123private:
124 /// Given a name without "__imp_" prefix, returns a defined symbol
125 /// with the "__imp_" prefix, if it exists.
126 Defined *impSymbol(StringRef name);
127 /// Inserts symbol if not already present.
128 std::pair<Symbol *, bool> insert(StringRef name);
129 /// Same as insert(Name), but also sets isUsedInRegularObj.
130 std::pair<Symbol *, bool> insert(StringRef name, InputFile *f);
131
132 std::vector<Symbol *> getSymsWithPrefix(StringRef prefix);
133
134 llvm::DenseMap<llvm::CachedHashStringRef, Symbol *> symMap;
135 std::unique_ptr<BitcodeCompiler> lto;
136 bool ltoCompilationDone = false;
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

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source code of lld/COFF/SymbolTable.h