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 {
18struct Ctx;
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 SymbolTable(Ctx &ctx) : ctx(ctx) {}
42 ArrayRef<Symbol *> getSymbols() const { return symVector; }
43
44 void wrap(Symbol *sym, Symbol *real, Symbol *wrap);
45
46 Symbol *insert(StringRef name);
47
48 template <typename T> Symbol *addSymbol(const T &newSym) {
49 Symbol *sym = insert(name: newSym.getName());
50 sym->resolve(ctx, newSym);
51 return sym;
52 }
53 Symbol *addAndCheckDuplicate(Ctx &, const Defined &newSym);
54
55 void scanVersionScript();
56
57 Symbol *find(StringRef name);
58
59 void handleDynamicList();
60
61 Symbol *addUnusedUndefined(StringRef name,
62 uint8_t binding = llvm::ELF::STB_GLOBAL);
63
64 // Set of .so files to not link the same shared object file more than once.
65 llvm::DenseMap<llvm::CachedHashStringRef, SharedFile *> soNames;
66
67 // Comdat groups define "link once" sections. If two comdat groups have the
68 // same name, only one of them is linked, and the other is ignored. This map
69 // is used to uniquify them.
70 llvm::DenseMap<llvm::CachedHashStringRef, const InputFile *> comdatGroups;
71
72 // The Map of __acle_se_<sym>, <sym> pairs found in the input objects.
73 // Key is the <sym> name.
74 llvm::SmallMapVector<StringRef, ArmCmseEntryFunction, 1> cmseSymMap;
75
76 // Map of symbols defined in the Arm CMSE import library. The linker must
77 // preserve the addresses in the output objects.
78 llvm::StringMap<Defined *> cmseImportLib;
79
80 // True if <sym> from the input Arm CMSE import library is written to the
81 // output Arm CMSE import library.
82 llvm::StringMap<bool> inCMSEOutImpLib;
83
84private:
85 SmallVector<Symbol *, 0> findByVersion(SymbolVersion ver);
86 SmallVector<Symbol *, 0> findAllByVersion(SymbolVersion ver,
87 bool includeNonDefault);
88
89 llvm::StringMap<SmallVector<Symbol *, 0>> &getDemangledSyms();
90 bool assignExactVersion(SymbolVersion ver, uint16_t versionId,
91 StringRef versionName, bool includeNonDefault);
92 void assignWildcardVersion(SymbolVersion ver, uint16_t versionId,
93 bool includeNonDefault);
94
95 Ctx &ctx;
96
97 // Global symbols and a map from symbol name to the index. The order is not
98 // defined. We can use an arbitrary order, but it has to be deterministic even
99 // when cross linking.
100 llvm::DenseMap<llvm::CachedHashStringRef, int> symMap;
101 SmallVector<Symbol *, 0> symVector;
102
103 // A map from demangled symbol names to their symbol objects.
104 // This mapping is 1:N because two symbols with different versions
105 // can have the same name. We use this map to handle "extern C++ {}"
106 // directive in version scripts.
107 std::optional<llvm::StringMap<SmallVector<Symbol *, 0>>> demangledSyms;
108};
109
110} // namespace lld::elf
111
112#endif
113