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 17 namespace lld::elf { 18 19 class InputFile; 20 class SharedFile; 21 22 struct 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. 39 class SymbolTable { 40 public: getSymbols()41 ArrayRef<Symbol *> getSymbols() const { return symVector; } 42 43 void wrap(Symbol *sym, Symbol *real, Symbol *wrap); 44 45 Symbol *insert(StringRef name); 46 addSymbol(const T & newSym)47 template <typename T> Symbol *addSymbol(const T &newSym) { 48 Symbol *sym = insert(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 83 private: 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 }; 106 107 LLVM_LIBRARY_VISIBILITY extern SymbolTable symtab; 108 109 } // namespace lld::elf 110 111 #endif 112