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 "SyntheticSections.h" 12 #include "llvm/Demangle/Demangle.h" 13 14 using namespace llvm; 15 using namespace lld; 16 using namespace lld::macho; 17 18 static_assert(sizeof(void *) != 8 || sizeof(Symbol) == 56, 19 "Try to minimize Symbol's size; we create many instances"); 20 21 // The Microsoft ABI doesn't support using parent class tail padding for child 22 // members, hence the _MSC_VER check. 23 #if !defined(_MSC_VER) 24 static_assert(sizeof(void *) != 8 || sizeof(Defined) == 88, 25 "Try to minimize Defined's size; we create many instances"); 26 #endif 27 28 static_assert(sizeof(SymbolUnion) == sizeof(Defined), 29 "Defined should be the largest Symbol kind"); 30 31 // Returns a symbol name for an error message. 32 static std::string maybeDemangleSymbol(StringRef symName) { 33 if (config->demangle) { 34 symName.consume_front("_"); 35 return demangle(symName); 36 } 37 return symName.str(); 38 } 39 40 std::string lld::toString(const Symbol &sym) { 41 return maybeDemangleSymbol(sym.getName()); 42 } 43 44 std::string lld::toMachOString(const object::Archive::Symbol &b) { 45 return maybeDemangleSymbol(b.getName()); 46 } 47 48 uint64_t Symbol::getStubVA() const { return in.stubs->getVA(stubsIndex); } 49 uint64_t Symbol::getLazyPtrVA() const { 50 return in.lazyPointers->getVA(stubsIndex); 51 } 52 uint64_t Symbol::getGotVA() const { return in.got->getVA(gotIndex); } 53 uint64_t Symbol::getTlvVA() const { return in.tlvPointers->getVA(gotIndex); } 54 55 Defined::Defined(StringRefZ name, InputFile *file, InputSection *isec, 56 uint64_t value, uint64_t size, bool isWeakDef, bool isExternal, 57 bool isPrivateExtern, bool includeInSymtab, 58 bool isReferencedDynamically, bool noDeadStrip, 59 bool canOverrideWeakDef, bool isWeakDefCanBeHidden, 60 bool interposable) 61 : Symbol(DefinedKind, name, file), overridesWeakDef(canOverrideWeakDef), 62 privateExtern(isPrivateExtern), includeInSymtab(includeInSymtab), 63 wasIdenticalCodeFolded(false), 64 referencedDynamically(isReferencedDynamically), noDeadStrip(noDeadStrip), 65 interposable(interposable), weakDefCanBeHidden(isWeakDefCanBeHidden), 66 weakDef(isWeakDef), external(isExternal), originalIsec(isec), 67 value(value), size(size) { 68 if (isec) { 69 isec->symbols.push_back(this); 70 // Maintain sorted order. 71 for (auto it = isec->symbols.rbegin(), rend = isec->symbols.rend(); 72 it != rend; ++it) { 73 auto next = std::next(it); 74 if (next == rend) 75 break; 76 if ((*it)->value < (*next)->value) 77 std::swap(*next, *it); 78 else 79 break; 80 } 81 } 82 } 83 84 bool Defined::isTlv() const { 85 return !isAbsolute() && isThreadLocalVariables(originalIsec->getFlags()); 86 } 87 88 uint64_t Defined::getVA() const { 89 assert(isLive() && "this should only be called for live symbols"); 90 91 if (isAbsolute()) 92 return value; 93 94 if (!isec()->isFinal) { 95 // A target arch that does not use thunks ought never ask for 96 // the address of a function that has not yet been finalized. 97 assert(target->usesThunks()); 98 99 // ConcatOutputSection::finalize() can seek the address of a 100 // function before its address is assigned. The thunking algorithm 101 // knows that unfinalized functions will be out of range, so it is 102 // expedient to return a contrived out-of-range address. 103 return TargetInfo::outOfRangeVA; 104 } 105 return isec()->getVA(value); 106 } 107 108 ObjFile *Defined::getObjectFile() const { 109 return originalIsec ? dyn_cast_or_null<ObjFile>(originalIsec->getFile()) 110 : nullptr; 111 } 112 113 std::string Defined::getSourceLocation() { 114 if (!originalIsec) 115 return {}; 116 return originalIsec->getSourceLocation(value); 117 } 118 119 // Get the canonical InputSection of the symbol. 120 InputSection *Defined::isec() const { 121 return originalIsec ? originalIsec->canonical() : nullptr; 122 } 123 124 // Get the canonical unwind entry of the symbol. 125 ConcatInputSection *Defined::unwindEntry() const { 126 return originalUnwindEntry ? originalUnwindEntry->canonical() : nullptr; 127 } 128 129 uint64_t DylibSymbol::getVA() const { 130 return isInStubs() ? getStubVA() : Symbol::getVA(); 131 } 132 133 void LazyArchive::fetchArchiveMember() { getFile()->fetch(sym); } 134