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_ELF_SYMBOL_TABLE_H
10#define LLD_ELF_SYMBOL_TABLE_H
11
12#include "Symbols.h"
13#include "llvm/ADT/CachedHashString.h"
14#include "llvm/ADT/DenseMap.h"
15#include "llvm/Support/Compiler.h"
16
17namespace lld::elf {
18
19class InputFile;
20class SharedFile;
21
22struct ArmCmseEntryFunction {
23 Symbol *acleSeSym;
24 Symbol *sym;
25};
26
27// SymbolTable is a bucket of all known symbols, including defined,
28// undefined, or lazy symbols (the last one is symbols in archive
29// files whose archive members are not yet loaded).
30//
31// We put all symbols of all files to a SymbolTable, and the
32// SymbolTable selects the "best" symbols if there are name
33// conflicts. For example, obviously, a defined symbol is better than
34// an undefined symbol. Or, if there's a conflict between a lazy and a
35// undefined, it'll read an archive member to read a real definition
36// to replace the lazy symbol. The logic is implemented in the
37// add*() functions, which are called by input files as they are parsed. There
38// is one add* function per symbol type.
39class SymbolTable {
40public:
41 ArrayRef<Symbol *> getSymbols() const { return symVector; }
42
43 void wrap(Symbol *sym, Symbol *real, Symbol *wrap);
44
45 Symbol *insert(StringRef name);
46
47 template <typename T> Symbol *addSymbol(const T &newSym) {
48 Symbol *sym = insert(name: newSym.getName());
49 sym->resolve(newSym);
50 return sym;
51 }
52 Symbol *addAndCheckDuplicate(const Defined &newSym);
53
54 void scanVersionScript();
55
56 Symbol *find(StringRef name);
57
58 void handleDynamicList();
59
60 Symbol *addUnusedUndefined(StringRef name,
61 uint8_t binding = llvm::ELF::STB_GLOBAL);
62
63 // Set of .so files to not link the same shared object file more than once.
64 llvm::DenseMap<llvm::CachedHashStringRef, SharedFile *> soNames;
65
66 // Comdat groups define "link once" sections. If two comdat groups have the
67 // same name, only one of them is linked, and the other is ignored. This map
68 // is used to uniquify them.
69 llvm::DenseMap<llvm::CachedHashStringRef, const InputFile *> comdatGroups;
70
71 // The Map of __acle_se_<sym>, <sym> pairs found in the input objects.
72 // Key is the <sym> name.
73 llvm::SmallMapVector<StringRef, ArmCmseEntryFunction, 1> cmseSymMap;
74
75 // Map of symbols defined in the Arm CMSE import library. The linker must
76 // preserve the addresses in the output objects.
77 llvm::StringMap<Defined *> cmseImportLib;
78
79 // True if <sym> from the input Arm CMSE import library is written to the
80 // output Arm CMSE import library.
81 llvm::StringMap<bool> inCMSEOutImpLib;
82
83private:
84 SmallVector<Symbol *, 0> findByVersion(SymbolVersion ver);
85 SmallVector<Symbol *, 0> findAllByVersion(SymbolVersion ver,
86 bool includeNonDefault);
87
88 llvm::StringMap<SmallVector<Symbol *, 0>> &getDemangledSyms();
89 bool assignExactVersion(SymbolVersion ver, uint16_t versionId,
90 StringRef versionName, bool includeNonDefault);
91 void assignWildcardVersion(SymbolVersion ver, uint16_t versionId,
92 bool includeNonDefault);
93
94 // Global symbols and a map from symbol name to the index. The order is not
95 // defined. We can use an arbitrary order, but it has to be deterministic even
96 // when cross linking.
97 llvm::DenseMap<llvm::CachedHashStringRef, int> symMap;
98 SmallVector<Symbol *, 0> symVector;
99
100 // A map from demangled symbol names to their symbol objects.
101 // This mapping is 1:N because two symbols with different versions
102 // can have the same name. We use this map to handle "extern C++ {}"
103 // directive in version scripts.
104 std::optional<llvm::StringMap<SmallVector<Symbol *, 0>>> demangledSyms;
105};
106
107LLVM_LIBRARY_VISIBILITY extern SymbolTable symtab;
108
109} // namespace lld::elf
110
111#endif
112