diff options
Diffstat (limited to 'lld/MachO/SymbolTable.cpp')
| -rw-r--r-- | lld/MachO/SymbolTable.cpp | 235 |
1 files changed, 178 insertions, 57 deletions
diff --git a/lld/MachO/SymbolTable.cpp b/lld/MachO/SymbolTable.cpp index 2f0844fadaaa..c5808a89bf57 100644 --- a/lld/MachO/SymbolTable.cpp +++ b/lld/MachO/SymbolTable.cpp @@ -7,9 +7,11 @@ //===----------------------------------------------------------------------===// #include "SymbolTable.h" +#include "ConcatOutputSection.h" #include "Config.h" #include "InputFiles.h" #include "Symbols.h" +#include "SyntheticSections.h" #include "lld/Common/ErrorHandler.h" #include "lld/Common/Memory.h" @@ -17,72 +19,99 @@ using namespace llvm; using namespace lld; using namespace lld::macho; -Symbol *SymbolTable::find(StringRef name) { - auto it = symMap.find(CachedHashStringRef(name)); +Symbol *SymbolTable::find(CachedHashStringRef cachedName) { + auto it = symMap.find(cachedName); if (it == symMap.end()) return nullptr; return symVector[it->second]; } -std::pair<Symbol *, bool> SymbolTable::insert(StringRef name) { +std::pair<Symbol *, bool> SymbolTable::insert(StringRef name, + const InputFile *file) { auto p = symMap.insert({CachedHashStringRef(name), (int)symVector.size()}); - // Name already present in the symbol table. - if (!p.second) - return {symVector[p.first->second], false}; + Symbol *sym; + if (!p.second) { + // Name already present in the symbol table. + sym = symVector[p.first->second]; + } else { + // Name is a new symbol. + sym = reinterpret_cast<Symbol *>(make<SymbolUnion>()); + symVector.push_back(sym); + } - // Name is a new symbol. - Symbol *sym = reinterpret_cast<Symbol *>(make<SymbolUnion>()); - symVector.push_back(sym); - return {sym, true}; + sym->isUsedInRegularObj |= !file || isa<ObjFile>(file); + return {sym, p.second}; } -Symbol *SymbolTable::addDefined(StringRef name, InputSection *isec, - uint32_t value, bool isWeakDef, - bool isPrivateExtern) { +Defined *SymbolTable::addDefined(StringRef name, InputFile *file, + InputSection *isec, uint64_t value, + uint64_t size, bool isWeakDef, + bool isPrivateExtern, bool isThumb, + bool isReferencedDynamically, + bool noDeadStrip) { Symbol *s; bool wasInserted; bool overridesWeakDef = false; - std::tie(s, wasInserted) = insert(name); + std::tie(s, wasInserted) = insert(name, file); + + assert(!isWeakDef || (isa<BitcodeFile>(file) && !isec) || + (isa<ObjFile>(file) && file == isec->getFile())); if (!wasInserted) { if (auto *defined = dyn_cast<Defined>(s)) { if (isWeakDef) { - // Both old and new symbol weak (e.g. inline function in two TUs): - // If one of them isn't private extern, the merged symbol isn't. - if (defined->isWeakDef()) + if (defined->isWeakDef()) { + // Both old and new symbol weak (e.g. inline function in two TUs): + // If one of them isn't private extern, the merged symbol isn't. defined->privateExtern &= isPrivateExtern; - return s; + defined->referencedDynamically |= isReferencedDynamically; + defined->noDeadStrip |= noDeadStrip; + + // FIXME: Handle this for bitcode files. + // FIXME: We currently only do this if both symbols are weak. + // We could do this if either is weak (but getting the + // case where !isWeakDef && defined->isWeakDef() right + // requires some care and testing). + if (auto concatIsec = dyn_cast_or_null<ConcatInputSection>(isec)) + concatIsec->wasCoalesced = true; + } + + return defined; } if (!defined->isWeakDef()) - error("duplicate symbol: " + name); + error("duplicate symbol: " + name + "\n>>> defined in " + + toString(defined->getFile()) + "\n>>> defined in " + + toString(file)); } else if (auto *dysym = dyn_cast<DylibSymbol>(s)) { overridesWeakDef = !isWeakDef && dysym->isWeakDef(); + dysym->unreference(); } // Defined symbols take priority over other types of symbols, so in case // of a name conflict, we fall through to the replaceSymbol() call below. } - Defined *defined = - replaceSymbol<Defined>(s, name, isec, value, isWeakDef, - /*isExternal=*/true, isPrivateExtern); + Defined *defined = replaceSymbol<Defined>( + s, name, file, isec, value, size, isWeakDef, /*isExternal=*/true, + isPrivateExtern, isThumb, isReferencedDynamically, noDeadStrip); defined->overridesWeakDef = overridesWeakDef; - return s; + return defined; } -Symbol *SymbolTable::addUndefined(StringRef name, bool isWeakRef) { +Symbol *SymbolTable::addUndefined(StringRef name, InputFile *file, + bool isWeakRef) { Symbol *s; bool wasInserted; - std::tie(s, wasInserted) = insert(name); + std::tie(s, wasInserted) = insert(name, file); - auto refState = isWeakRef ? RefState::Weak : RefState::Strong; + RefState refState = isWeakRef ? RefState::Weak : RefState::Strong; if (wasInserted) - replaceSymbol<Undefined>(s, name, refState); + replaceSymbol<Undefined>(s, name, file, refState); else if (auto *lazy = dyn_cast<LazySymbol>(s)) lazy->fetchArchiveMember(); else if (auto *dynsym = dyn_cast<DylibSymbol>(s)) - dynsym->refState = std::max(dynsym->refState, refState); + dynsym->reference(refState); else if (auto *undefined = dyn_cast<Undefined>(s)) undefined->refState = std::max(undefined->refState, refState); return s; @@ -92,7 +121,7 @@ Symbol *SymbolTable::addCommon(StringRef name, InputFile *file, uint64_t size, uint32_t align, bool isPrivateExtern) { Symbol *s; bool wasInserted; - std::tie(s, wasInserted) = insert(name); + std::tie(s, wasInserted) = insert(name, file); if (!wasInserted) { if (auto *common = dyn_cast<CommonSymbol>(s)) { @@ -113,9 +142,9 @@ Symbol *SymbolTable::addDylib(StringRef name, DylibFile *file, bool isWeakDef, bool isTlv) { Symbol *s; bool wasInserted; - std::tie(s, wasInserted) = insert(name); + std::tie(s, wasInserted) = insert(name, file); - auto refState = RefState::Unreferenced; + RefState refState = RefState::Unreferenced; if (!wasInserted) { if (auto *defined = dyn_cast<Defined>(s)) { if (isWeakDef && !defined->isWeakDef()) @@ -123,22 +152,32 @@ Symbol *SymbolTable::addDylib(StringRef name, DylibFile *file, bool isWeakDef, } else if (auto *undefined = dyn_cast<Undefined>(s)) { refState = undefined->refState; } else if (auto *dysym = dyn_cast<DylibSymbol>(s)) { - refState = dysym->refState; + refState = dysym->getRefState(); } } + bool isDynamicLookup = file == nullptr; if (wasInserted || isa<Undefined>(s) || - (isa<DylibSymbol>(s) && !isWeakDef && s->isWeakDef())) + (isa<DylibSymbol>(s) && + ((!isWeakDef && s->isWeakDef()) || + (!isDynamicLookup && cast<DylibSymbol>(s)->isDynamicLookup())))) { + if (auto *dynsym = dyn_cast<DylibSymbol>(s)) + dynsym->unreference(); replaceSymbol<DylibSymbol>(s, file, name, isWeakDef, refState, isTlv); + } return s; } +Symbol *SymbolTable::addDynamicLookup(StringRef name) { + return addDylib(name, /*file=*/nullptr, /*isWeakDef=*/false, /*isTlv=*/false); +} + Symbol *SymbolTable::addLazy(StringRef name, ArchiveFile *file, const object::Archive::Symbol &sym) { Symbol *s; bool wasInserted; - std::tie(s, wasInserted) = insert(name); + std::tie(s, wasInserted) = insert(name, file); if (wasInserted) replaceSymbol<LazySymbol>(s, file, sym); @@ -147,37 +186,119 @@ Symbol *SymbolTable::addLazy(StringRef name, ArchiveFile *file, return s; } -Symbol *SymbolTable::addDSOHandle(const MachHeaderSection *header) { - Symbol *s; - bool wasInserted; - std::tie(s, wasInserted) = insert(DSOHandle::name); - if (!wasInserted) { - // FIXME: Make every symbol (including absolute symbols) contain a - // reference to their originating file, then add that file name to this - // error message. - if (isa<Defined>(s)) - error("found defined symbol with illegal name " + DSOHandle::name); - } - replaceSymbol<DSOHandle>(s, header); +Defined *SymbolTable::addSynthetic(StringRef name, InputSection *isec, + uint64_t value, bool isPrivateExtern, + bool includeInSymtab, + bool referencedDynamically) { + Defined *s = addDefined(name, nullptr, isec, value, /*size=*/0, + /*isWeakDef=*/false, isPrivateExtern, + /*isThumb=*/false, referencedDynamically, + /*noDeadStrip=*/false); + s->includeInSymtab = includeInSymtab; return s; } -void lld::macho::treatUndefinedSymbol(StringRef symbolName, - StringRef fileName) { - std::string message = ("undefined symbol: " + symbolName).str(); - if (!fileName.empty()) - message += ("\n>>> referenced by " + fileName).str(); +enum class Boundary { + Start, + End, +}; + +static Defined *createBoundarySymbol(const Undefined &sym) { + return symtab->addSynthetic( + sym.getName(), /*isec=*/nullptr, /*value=*/-1, /*isPrivateExtern=*/true, + /*includeInSymtab=*/false, /*referencedDynamically=*/false); +} + +static void handleSectionBoundarySymbol(const Undefined &sym, StringRef segSect, + Boundary which) { + StringRef segName, sectName; + std::tie(segName, sectName) = segSect.split('$'); + + // Attach the symbol to any InputSection that will end up in the right + // OutputSection -- it doesn't matter which one we pick. + // Don't bother looking through inputSections for a matching + // ConcatInputSection -- we need to create ConcatInputSection for + // non-existing sections anyways, and that codepath works even if we should + // already have a ConcatInputSection with the right name. + + OutputSection *osec = nullptr; + // This looks for __TEXT,__cstring etc. + for (SyntheticSection *ssec : syntheticSections) + if (ssec->segname == segName && ssec->name == sectName) { + osec = ssec->isec->parent; + break; + } + + if (!osec) { + ConcatInputSection *isec = make<ConcatInputSection>(segName, sectName); + + // This runs after markLive() and is only called for Undefineds that are + // live. Marking the isec live ensures an OutputSection is created that the + // start/end symbol can refer to. + assert(sym.isLive()); + isec->live = true; + + // This runs after gatherInputSections(), so need to explicitly set parent + // and add to inputSections. + osec = isec->parent = ConcatOutputSection::getOrCreateForInput(isec); + inputSections.push_back(isec); + } + + if (which == Boundary::Start) + osec->sectionStartSymbols.push_back(createBoundarySymbol(sym)); + else + osec->sectionEndSymbols.push_back(createBoundarySymbol(sym)); +} + +static void handleSegmentBoundarySymbol(const Undefined &sym, StringRef segName, + Boundary which) { + OutputSegment *seg = getOrCreateOutputSegment(segName); + if (which == Boundary::Start) + seg->segmentStartSymbols.push_back(createBoundarySymbol(sym)); + else + seg->segmentEndSymbols.push_back(createBoundarySymbol(sym)); +} + +void lld::macho::treatUndefinedSymbol(const Undefined &sym, StringRef source) { + // Handle start/end symbols. + StringRef name = sym.getName(); + if (name.consume_front("section$start$")) + return handleSectionBoundarySymbol(sym, name, Boundary::Start); + if (name.consume_front("section$end$")) + return handleSectionBoundarySymbol(sym, name, Boundary::End); + if (name.consume_front("segment$start$")) + return handleSegmentBoundarySymbol(sym, name, Boundary::Start); + if (name.consume_front("segment$end$")) + return handleSegmentBoundarySymbol(sym, name, Boundary::End); + + // Handle -U. + if (config->explicitDynamicLookups.count(sym.getName())) { + symtab->addDynamicLookup(sym.getName()); + return; + } + + // Handle -undefined. + auto message = [source, &sym]() { + std::string message = "undefined symbol"; + if (config->archMultiple) + message += (" for arch " + getArchitectureName(config->arch())).str(); + message += ": " + toString(sym); + if (!source.empty()) + message += "\n>>> referenced by " + source.str(); + else + message += "\n>>> referenced by " + toString(sym.getFile()); + return message; + }; switch (config->undefinedSymbolTreatment) { - case UndefinedSymbolTreatment::suppress: - break; case UndefinedSymbolTreatment::error: - error(message); + error(message()); break; case UndefinedSymbolTreatment::warning: - warn(message); - break; + warn(message()); + LLVM_FALLTHROUGH; case UndefinedSymbolTreatment::dynamic_lookup: - error("dynamic_lookup unimplemented for " + message); + case UndefinedSymbolTreatment::suppress: + symtab->addDynamicLookup(sym.getName()); break; case UndefinedSymbolTreatment::unknown: llvm_unreachable("unknown -undefined TREATMENT"); |