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//===- Symbols.cpp --------------------------------------------------------===//
// The LLVM Linker
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
#include "Symbols.h"
#include "InputFiles.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/Memory.h"
#include "lld/Common/Strings.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace llvm::object;
// Returns a symbol name for an error message.
std::string lld::toString(coff::Symbol &B) {
if (Optional<std::string> S = lld::demangleMSVC(B.getName()))
return ("\"" + *S + "\" (" + B.getName() + ")").str();
return B.getName();
namespace lld {
namespace coff {
StringRef Symbol::getName() {
// COFF symbol names are read lazily for a performance reason.
// Non-external symbol names are never used by the linker except for logging
// or debugging. Their internal references are resolved not by name but by
// symbol index. And because they are not external, no one can refer them by
// name. Object files contain lots of non-external symbols, and creating
// StringRefs for them (which involves lots of strlen() on the string table)
// is a waste of time.
if (Name.empty()) {
auto *D = cast<DefinedCOFF>(this);
cast<ObjFile>(D->File)->getCOFFObj()->getSymbolName(D->Sym, Name);
return Name;
InputFile *Symbol::getFile() {
if (auto *Sym = dyn_cast<DefinedCOFF>(this))
return Sym->File;
if (auto *Sym = dyn_cast<Lazy>(this))
return Sym->File;
return nullptr;
bool Symbol::isLive() const {
if (auto *R = dyn_cast<DefinedRegular>(this))
return R->getChunk()->isLive();
if (auto *Imp = dyn_cast<DefinedImportData>(this))
return Imp->File->Live;
if (auto *Imp = dyn_cast<DefinedImportThunk>(this))
return Imp->WrappedSym->File->ThunkLive;
// Assume any other kind of symbol is live.
return true;
COFFSymbolRef DefinedCOFF::getCOFFSymbol() {
size_t SymSize = cast<ObjFile>(File)->getCOFFObj()->getSymbolTableEntrySize();
if (SymSize == sizeof(coff_symbol16))
return COFFSymbolRef(reinterpret_cast<const coff_symbol16 *>(Sym));
assert(SymSize == sizeof(coff_symbol32));
return COFFSymbolRef(reinterpret_cast<const coff_symbol32 *>(Sym));
uint16_t DefinedAbsolute::NumOutputSections;
static Chunk *makeImportThunk(DefinedImportData *S, uint16_t Machine) {
if (Machine == AMD64)
return make<ImportThunkChunkX64>(S);
if (Machine == I386)
return make<ImportThunkChunkX86>(S);
if (Machine == ARM64)
return make<ImportThunkChunkARM64>(S);
assert(Machine == ARMNT);
return make<ImportThunkChunkARM>(S);
DefinedImportThunk::DefinedImportThunk(StringRef Name, DefinedImportData *S,
uint16_t Machine)
: Defined(DefinedImportThunkKind, Name), WrappedSym(S),
Data(makeImportThunk(S, Machine)) {}
Defined *Undefined::getWeakAlias() {
// A weak alias may be a weak alias to another symbol, so check recursively.
for (Symbol *A = WeakAlias; A; A = cast<Undefined>(A)->WeakAlias)
if (auto *D = dyn_cast<Defined>(A))
return D;
return nullptr;
} // namespace coff
} // namespace lld