SymbolTable.h revision 360784 
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 {
24namespace coff {
25
26class Chunk;
27class CommonChunk;
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  void addFile(InputFile *file);
51
52  // Emit errors for symbols that cannot be resolved.
53  void reportUnresolvable();
54
55  // Try to resolve any undefined symbols and update the symbol table
56  // accordingly, then print an error message for any remaining undefined
57  // symbols and warn about imported local symbols.
58  void resolveRemainingUndefines();
59
60  void loadMinGWAutomaticImports();
61  bool handleMinGWAutomaticImport(Symbol *sym, StringRef name);
62
63  // Returns a list of chunks of selected symbols.
64  std::vector<Chunk *> getChunks();
65
66  // Returns a symbol for a given name. Returns a nullptr if not found.
67  Symbol *find(StringRef name);
68  Symbol *findUnderscore(StringRef name);
69
70  // Occasionally we have to resolve an undefined symbol to its
71  // mangled symbol. This function tries to find a mangled name
72  // for U from the symbol table, and if found, set the symbol as
73  // a weak alias for U.
74  Symbol *findMangle(StringRef name);
75
76  // Build a set of COFF objects representing the combined contents of
77  // BitcodeFiles and add them to the symbol table. Called after all files are
78  // added and before the writer writes results to a file.
79  void addCombinedLTOObjects();
80  std::vector<StringRef> compileBitcodeFiles();
81
82  // Creates an Undefined symbol for a given name.
83  Symbol *addUndefined(StringRef name);
84
85  Symbol *addSynthetic(StringRef n, Chunk *c);
86  Symbol *addAbsolute(StringRef n, uint64_t va);
87
88  Symbol *addUndefined(StringRef name, InputFile *f, bool isWeakAlias);
89  void addLazyArchive(ArchiveFile *f, const Archive::Symbol &sym);
90  void addLazyObject(LazyObjFile *f, StringRef n);
91  Symbol *addAbsolute(StringRef n, COFFSymbolRef s);
92  Symbol *addRegular(InputFile *f, StringRef n,
93                     const llvm::object::coff_symbol_generic *s = nullptr,
94                     SectionChunk *c = nullptr, uint32_t sectionOffset = 0);
95  std::pair<DefinedRegular *, bool>
96  addComdat(InputFile *f, StringRef n,
97            const llvm::object::coff_symbol_generic *s = nullptr);
98  Symbol *addCommon(InputFile *f, StringRef n, uint64_t size,
99                    const llvm::object::coff_symbol_generic *s = nullptr,
100                    CommonChunk *c = nullptr);
101  Symbol *addImportData(StringRef n, ImportFile *f);
102  Symbol *addImportThunk(StringRef name, DefinedImportData *s,
103                         uint16_t machine);
104  void addLibcall(StringRef name);
105
106  void reportDuplicate(Symbol *existing, InputFile *newFile,
107                       SectionChunk *newSc = nullptr,
108                       uint32_t newSectionOffset = 0);
109
110  // A list of chunks which to be added to .rdata.
111  std::vector<Chunk *> localImportChunks;
112
113  // Iterates symbols in non-determinstic hash table order.
114  template <typename T> void forEachSymbol(T callback) {
115    for (auto &pair : symMap)
116      callback(pair.second);
117  }
118
119private:
120  /// Given a name without "__imp_" prefix, returns a defined symbol
121  /// with the "__imp_" prefix, if it exists.
122  Defined *impSymbol(StringRef name);
123  /// Inserts symbol if not already present.
124  std::pair<Symbol *, bool> insert(StringRef name);
125  /// Same as insert(Name), but also sets isUsedInRegularObj.
126  std::pair<Symbol *, bool> insert(StringRef name, InputFile *f);
127
128  std::vector<Symbol *> getSymsWithPrefix(StringRef prefix);
129
130  llvm::DenseMap<llvm::CachedHashStringRef, Symbol *> symMap;
131  std::unique_ptr<BitcodeCompiler> lto;
132};
133
134extern SymbolTable *symtab;
135
136std::vector<std::string> getSymbolLocations(ObjFile *file, uint32_t symIndex);
137
138} // namespace coff
139} // namespace lld
140
141#endif
142