1 //===- Symbols.cpp --------------------------------------------------------===// 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 #include "Symbols.h" 10 #include "InputFiles.h" 11 #include "lld/Common/ErrorHandler.h" 12 #include "lld/Common/Memory.h" 13 #include "lld/Common/Strings.h" 14 #include "llvm/ADT/STLExtras.h" 15 #include "llvm/Demangle/Demangle.h" 16 #include "llvm/Support/Debug.h" 17 #include "llvm/Support/raw_ostream.h" 18 19 using namespace llvm; 20 using namespace llvm::object; 21 22 using namespace lld::coff; 23 24 namespace lld { 25 26 static_assert(sizeof(SymbolUnion) <= 48, 27 "symbols should be optimized for memory usage"); 28 29 // Returns a symbol name for an error message. 30 static std::string maybeDemangleSymbol(StringRef symName) { 31 if (config->demangle) { 32 std::string prefix; 33 StringRef prefixless = symName; 34 if (prefixless.consume_front("__imp_")) 35 prefix = "__declspec(dllimport) "; 36 StringRef demangleInput = prefixless; 37 if (config->machine == I386) 38 demangleInput.consume_front("_"); 39 std::string demangled = demangle(std::string(demangleInput)); 40 if (demangled != demangleInput) 41 return prefix + demangle(std::string(demangleInput)); 42 return (prefix + prefixless).str(); 43 } 44 return std::string(symName); 45 } 46 std::string toString(coff::Symbol &b) { 47 return maybeDemangleSymbol(b.getName()); 48 } 49 std::string toCOFFString(const Archive::Symbol &b) { 50 return maybeDemangleSymbol(b.getName()); 51 } 52 53 namespace coff { 54 55 void Symbol::computeName() { 56 assert(nameData == nullptr && 57 "should only compute the name once for DefinedCOFF symbols"); 58 auto *d = cast<DefinedCOFF>(this); 59 StringRef nameStr = 60 check(cast<ObjFile>(d->file)->getCOFFObj()->getSymbolName(d->sym)); 61 nameData = nameStr.data(); 62 nameSize = nameStr.size(); 63 assert(nameSize == nameStr.size() && "name length truncated"); 64 } 65 66 InputFile *Symbol::getFile() { 67 if (auto *sym = dyn_cast<DefinedCOFF>(this)) 68 return sym->file; 69 if (auto *sym = dyn_cast<LazyArchive>(this)) 70 return sym->file; 71 if (auto *sym = dyn_cast<LazyObject>(this)) 72 return sym->file; 73 if (auto *sym = dyn_cast<LazyDLLSymbol>(this)) 74 return sym->file; 75 return nullptr; 76 } 77 78 bool Symbol::isLive() const { 79 if (auto *r = dyn_cast<DefinedRegular>(this)) 80 return r->getChunk()->live; 81 if (auto *imp = dyn_cast<DefinedImportData>(this)) 82 return imp->file->live; 83 if (auto *imp = dyn_cast<DefinedImportThunk>(this)) 84 return imp->wrappedSym->file->thunkLive; 85 // Assume any other kind of symbol is live. 86 return true; 87 } 88 89 // MinGW specific. 90 void Symbol::replaceKeepingName(Symbol *other, size_t size) { 91 StringRef origName = getName(); 92 memcpy(this, other, size); 93 nameData = origName.data(); 94 nameSize = origName.size(); 95 } 96 97 COFFSymbolRef DefinedCOFF::getCOFFSymbol() { 98 size_t symSize = cast<ObjFile>(file)->getCOFFObj()->getSymbolTableEntrySize(); 99 if (symSize == sizeof(coff_symbol16)) 100 return COFFSymbolRef(reinterpret_cast<const coff_symbol16 *>(sym)); 101 assert(symSize == sizeof(coff_symbol32)); 102 return COFFSymbolRef(reinterpret_cast<const coff_symbol32 *>(sym)); 103 } 104 105 uint16_t DefinedAbsolute::numOutputSections; 106 107 static Chunk *makeImportThunk(DefinedImportData *s, uint16_t machine) { 108 if (machine == AMD64) 109 return make<ImportThunkChunkX64>(s); 110 if (machine == I386) 111 return make<ImportThunkChunkX86>(s); 112 if (machine == ARM64) 113 return make<ImportThunkChunkARM64>(s); 114 assert(machine == ARMNT); 115 return make<ImportThunkChunkARM>(s); 116 } 117 118 DefinedImportThunk::DefinedImportThunk(StringRef name, DefinedImportData *s, 119 uint16_t machine) 120 : Defined(DefinedImportThunkKind, name), wrappedSym(s), 121 data(makeImportThunk(s, machine)) {} 122 123 Defined *Undefined::getWeakAlias() { 124 // A weak alias may be a weak alias to another symbol, so check recursively. 125 for (Symbol *a = weakAlias; a; a = cast<Undefined>(a)->weakAlias) 126 if (auto *d = dyn_cast<Defined>(a)) 127 return d; 128 return nullptr; 129 } 130 131 MemoryBufferRef LazyArchive::getMemberBuffer() { 132 Archive::Child c = 133 CHECK(sym.getMember(), 134 "could not get the member for symbol " + toCOFFString(sym)); 135 return CHECK(c.getMemoryBufferRef(), 136 "could not get the buffer for the member defining symbol " + 137 toCOFFString(sym)); 138 } 139 } // namespace coff 140 } // namespace lld 141