Symbol *SymbolTable<ELFT>::addCommon(StringRef N, uint64_t Size,
uint64_t Alignment, uint8_t Binding,
uint8_t StOther, uint8_t Type,
InputFile *File) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) =
insert(N, Type, StOther & 3, /*CanOmitFromDynSym*/ false,
/*IsUsedInRegularObj*/ true, File);
int Cmp = compareDefined(S, WasInserted, Binding);
if (Cmp > 0) {
S->Binding = Binding;
replaceBody<DefinedCommon>(S, N, Size, Alignment, StOther, Type, File);
} else if (Cmp == 0) {
auto *C = dyn_cast<DefinedCommon>(S->body());
if (!C) {
// Non-common symbols take precedence over common symbols.
if (Config->WarnCommon)
warning("common " + S->body()->getName() + " is overridden");
return S;
}
if (Config->WarnCommon)
warning("multiple common of " + S->body()->getName());
C->Size = std::max(C->Size, Size);
C->Alignment = std::max(C->Alignment, Alignment);
}
return S;
}
void SymbolTable<ELFT>::addLazyArchive(ArchiveFile *F,
const object::Archive::Symbol Sym) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Sym.getName());
if (WasInserted) {
replaceBody<LazyArchive>(S, *F, Sym, SymbolBody::UnknownType);
return;
}
if (!S->body()->isUndefined())
return;
// Weak undefined symbols should not fetch members from archives. If we were
// to keep old symbol we would not know that an archive member was available
// if a strong undefined symbol shows up afterwards in the link. If a strong
// undefined symbol never shows up, this lazy symbol will get to the end of
// the link and must be treated as the weak undefined one. We already marked
// this symbol as used when we added it to the symbol table, but we also need
// to preserve its type. FIXME: Move the Type field to Symbol.
if (S->isWeak()) {
replaceBody<LazyArchive>(S, *F, Sym, S->body()->Type);
return;
}
MemoryBufferRef MBRef = F->getMember(&Sym);
if (!MBRef.getBuffer().empty())
addFile(createObjectFile(MBRef, F->getName()));
}
Symbol *SymbolTable<ELFT>::addUndefined(StringRef Name, uint8_t Binding,
uint8_t StOther, uint8_t Type,
bool CanOmitFromDynSym,
InputFile *File) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) =
insert(Name, Type, StOther & 3, CanOmitFromDynSym,
/*IsUsedInRegularObj*/ !File || !isa<BitcodeFile>(File), File);
if (WasInserted) {
S->Binding = Binding;
replaceBody<Undefined>(S, Name, StOther, Type, File);
return S;
}
if (Binding != STB_WEAK) {
if (S->body()->isShared() || S->body()->isLazy())
S->Binding = Binding;
if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(S->body()))
SS->file()->IsUsed = true;
}
if (auto *L = dyn_cast<Lazy>(S->body())) {
// An undefined weak will not fetch archive members, but we have to remember
// its type. See also comment in addLazyArchive.
if (S->isWeak())
L->Type = Type;
else if (auto F = L->fetch())
addFile(std::move(F));
}
return S;
}
void Writer::fixSafeSEHSymbols() {
if (!SEHTable)
return;
// Replace the absolute table symbol with a synthetic symbol pointing to the
// SEHTable chunk so that we can emit base relocations for it and resolve
// section relative relocations.
Symbol *T = Symtab->find("___safe_se_handler_table");
Symbol *C = Symtab->find("___safe_se_handler_count");
replaceBody<DefinedSynthetic>(T, T->body()->getName(), SEHTable);
cast<DefinedAbsolute>(C->body())->setVA(SEHTable->getSize() / 4);
}
DefinedRegular<ELFT> *SymbolTable<ELFT>::addAbsolute(StringRef Name,
uint8_t Visibility,
uint8_t Binding) {
Symbol *Sym =
addRegular(Name, Visibility, STT_NOTYPE, 0, 0, Binding, nullptr, nullptr);
return cast<DefinedRegular<ELFT>>(Sym->body());
}
void BitcodeCompiler::add(BitcodeFile &F) {
lto::InputFile &Obj = *F.Obj;
if (Obj.getDataLayoutStr().empty())
fatal("invalid bitcode file: " + F.getName() + " has no datalayout");
unsigned SymNum = 0;
std::vector<Symbol *> Syms = F.getSymbols();
std::vector<lto::SymbolResolution> Resols(Syms.size());
// Provide a resolution to the LTO API for each symbol.
for (const lto::InputFile::Symbol &ObjSym : Obj.symbols()) {
Symbol *Sym = Syms[SymNum];
lto::SymbolResolution &R = Resols[SymNum];
++SymNum;
SymbolBody *B = Sym->body();
// Ideally we shouldn't check for SF_Undefined but currently IRObjectFile
// reports two symbols for module ASM defined. Without this check, lld
// flags an undefined in IR with a definition in ASM as prevailing.
// Once IRObjectFile is fixed to report only one symbol this hack can
// be removed.
R.Prevailing =
!(ObjSym.getFlags() & object::BasicSymbolRef::SF_Undefined) &&
B->File == &F;
R.VisibleToRegularObj =
Sym->IsUsedInRegularObj || (R.Prevailing && Sym->includeInDynsym());
if (R.Prevailing)
undefine(Sym);
}
checkError(LtoObj->add(std::move(F.Obj), Resols));
}
std::pair<Symbol *, bool>
SymbolTable<ELFT>::insert(StringRef Name, uint8_t Type, uint8_t Visibility,
bool CanOmitFromDynSym, InputFile *File) {
bool IsUsedInRegularObj = !File || File->kind() == InputFile::ObjectKind;
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name);
// Merge in the new symbol's visibility.
S->Visibility = getMinVisibility(S->Visibility, Visibility);
if (!CanOmitFromDynSym && (Config->Shared || Config->ExportDynamic))
S->ExportDynamic = true;
if (IsUsedInRegularObj)
S->IsUsedInRegularObj = true;
if (!WasInserted && S->body()->Type != SymbolBody::UnknownType &&
((Type == STT_TLS) != S->body()->isTls()))
error("TLS attribute mismatch for symbol " + conflictMsg(S->body(), File));
return {S, WasInserted};
}
void SymbolTable<ELFT>::addLazyObject(StringRef Name, LazyObjectFile &Obj) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name);
if (WasInserted) {
replaceBody<LazyObject>(S, Name, Obj, SymbolBody::UnknownType);
return;
}
if (!S->body()->isUndefined())
return;
// See comment for addLazyArchive above.
if (S->isWeak()) {
replaceBody<LazyObject>(S, Name, Obj, S->body()->Type);
} else {
MemoryBufferRef MBRef = Obj.getBuffer();
if (!MBRef.getBuffer().empty())
addFile(createObjectFile(MBRef));
}
}
Symbol *SymbolTable<ELFT>::addRegular(StringRef Name, uint8_t Binding,
uint8_t StOther) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) =
insert(Name, STT_NOTYPE, StOther & 3, /*CanOmitFromDynSym*/ false,
/*IsUsedInRegularObj*/ true, nullptr);
int Cmp = compareDefinedNonCommon(S, WasInserted, Binding);
if (Cmp > 0)
replaceBody<DefinedRegular<ELFT>>(S, Name, StOther);
else if (Cmp == 0)
reportDuplicate(S->body(), nullptr);
return S;
}
Symbol *SymbolTable<ELFT>::addBitcode(StringRef Name, bool IsWeak,
uint8_t StOther, uint8_t Type,
bool CanOmitFromDynSym, BitcodeFile *F) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name, Type, StOther & 3, CanOmitFromDynSym,
/*IsUsedInRegularObj*/ false, F);
int Cmp =
compareDefinedNonCommon(S, WasInserted, IsWeak ? STB_WEAK : STB_GLOBAL);
if (Cmp > 0)
replaceBody<DefinedBitcode>(S, Name, StOther, Type, F);
else if (Cmp == 0)
reportDuplicate(S->body(), F);
return S;
}
Symbol *SymbolTable<ELFT>::addSynthetic(StringRef N,
OutputSectionBase<ELFT> *Section,
uintX_t Value) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) =
insert(N, STT_NOTYPE, STV_HIDDEN, /*CanOmitFromDynSym*/ false,
/*IsUsedInRegularObj*/ true, nullptr);
int Cmp = compareDefinedNonCommon(S, WasInserted, STB_GLOBAL);
if (Cmp > 0)
replaceBody<DefinedSynthetic<ELFT>>(S, N, Value, Section);
else if (Cmp == 0)
reportDuplicate(S->body(), nullptr);
return S;
}
Symbol *SymbolTable<ELFT>::addRegular(StringRef Name, const Elf_Sym &Sym,
InputSectionBase<ELFT> *Section) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) =
insert(Name, Sym.getType(), Sym.getVisibility(),
/*CanOmitFromDynSym*/ false, /*IsUsedInRegularObj*/ true,
Section ? Section->getFile() : nullptr);
int Cmp = compareDefinedNonCommon(S, WasInserted, Sym.getBinding());
if (Cmp > 0)
replaceBody<DefinedRegular<ELFT>>(S, Name, Sym, Section);
else if (Cmp == 0)
reportDuplicate(S->body(), Section->getFile());
return S;
}
Symbol *SymbolTable<ELFT>::addSynthetic(StringRef N,
const OutputSectionBase *Section,
uintX_t Value, uint8_t StOther) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(N, STT_NOTYPE, getVisibility(StOther),
/*CanOmitFromDynSym*/ false, nullptr);
int Cmp = compareDefinedNonCommon<ELFT>(S, WasInserted, STB_GLOBAL,
/*IsAbsolute*/ false, /*Value*/ 0);
if (Cmp > 0)
replaceBody<DefinedSynthetic>(S, N, Value, Section);
else if (Cmp == 0)
reportDuplicate(S->body(), nullptr);
return S;
}
Symbol *SymbolTable<ELFT>::addBitcode(StringRef Name, uint8_t Binding,
uint8_t StOther, uint8_t Type,
bool CanOmitFromDynSym, BitcodeFile *F) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) =
insert(Name, Type, getVisibility(StOther), CanOmitFromDynSym, F);
int Cmp = compareDefinedNonCommon<ELFT>(S, WasInserted, Binding,
/*IsAbs*/ false, /*Value*/ 0);
if (Cmp > 0)
replaceBody<DefinedRegular<ELFT>>(S, Name, /*IsLocal=*/false, StOther, Type,
0, 0, nullptr, F);
else if (Cmp == 0)
reportDuplicate(S->body(), F);
return S;
}
Symbol *SymbolTable<ELFT>::addRegular(StringRef Name, uint8_t StOther,
uint8_t Type, uintX_t Value, uintX_t Size,
uint8_t Binding,
InputSectionBase<ELFT> *Section,
InputFile *File) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name, Type, getVisibility(StOther),
/*CanOmitFromDynSym*/ false, File);
int Cmp = compareDefinedNonCommon<ELFT>(S, WasInserted, Binding,
Section == nullptr, Value);
if (Cmp > 0)
replaceBody<DefinedRegular<ELFT>>(S, Name, /*IsLocal=*/false, StOther, Type,
Value, Size, Section, File);
else if (Cmp == 0)
reportDuplicate(S->body(), Section, Value);
return S;
}
void SymbolTable<ELFT>::addShared(SharedFile<ELFT> *F, StringRef Name,
const Elf_Sym &Sym,
const typename ELFT::Verdef *Verdef) {
// DSO symbols do not affect visibility in the output, so we pass STV_DEFAULT
// as the visibility, which will leave the visibility in the symbol table
// unchanged.
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) =
insert(Name, Sym.getType(), STV_DEFAULT, /*CanOmitFromDynSym*/ true,
/*IsUsedInRegularObj*/ false, F);
// Make sure we preempt DSO symbols with default visibility.
if (Sym.getVisibility() == STV_DEFAULT)
S->ExportDynamic = true;
if (WasInserted || isa<Undefined>(S->body())) {
replaceBody<SharedSymbol<ELFT>>(S, F, Name, Sym, Verdef);
if (!S->isWeak())
F->IsUsed = true;
}
}
void SymbolTable<ELFT>::addShared(SharedFile<ELFT> *F, StringRef Name,
const Elf_Sym &Sym,
const typename ELFT::Verdef *Verdef) {
// DSO symbols do not affect visibility in the output, so we pass STV_DEFAULT
// as the visibility, which will leave the visibility in the symbol table
// unchanged.
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) =
insert(Name, Sym.getType(), STV_DEFAULT, /*CanOmitFromDynSym*/ true, F);
// Make sure we preempt DSO symbols with default visibility.
if (Sym.getVisibility() == STV_DEFAULT) {
S->ExportDynamic = true;
// Exporting preempting symbols takes precedence over linker scripts.
if (S->VersionId == VER_NDX_LOCAL)
S->VersionId = VER_NDX_GLOBAL;
}
if (WasInserted || isa<Undefined<ELFT>>(S->body())) {
replaceBody<SharedSymbol<ELFT>>(S, F, Name, Sym, Verdef);
if (!S->isWeak())
F->IsUsed = true;
}
}
void BitcodeCompiler::add(BitcodeFile &F) {
std::unique_ptr<IRObjectFile> Obj = std::move(F.Obj);
std::vector<GlobalValue *> Keep;
unsigned BodyIndex = 0;
ArrayRef<Symbol *> Syms = F.getSymbols();
Module &M = Obj->getModule();
if (M.getDataLayoutStr().empty())
fatal("invalid bitcode file: " + F.getName() + " has no datalayout");
// Discard non-compatible debug infos if necessary.
M.materializeMetadata();
UpgradeDebugInfo(M);
// If a symbol appears in @llvm.used, the linker is required
// to treat the symbol as there is a reference to the symbol
// that it cannot see. Therefore, we can't internalize.
SmallPtrSet<GlobalValue *, 8> Used;
collectUsedGlobalVariables(M, Used, /* CompilerUsed */ false);
for (const BasicSymbolRef &Sym : Obj->symbols()) {
uint32_t Flags = Sym.getFlags();
GlobalValue *GV = Obj->getSymbolGV(Sym.getRawDataRefImpl());
if (GV && GV->hasAppendingLinkage())
Keep.push_back(GV);
if (BitcodeFile::shouldSkip(Flags))
continue;
Symbol *S = Syms[BodyIndex++];
if (Flags & BasicSymbolRef::SF_Undefined) {
handleUndefinedAsmRefs(Sym, GV, AsmUndefinedRefs);
continue;
}
auto *B = dyn_cast<DefinedBitcode>(S->body());
if (!B || B->File != &F)
continue;
// We collect the set of symbols we want to internalize here
// and change the linkage after the IRMover executed, i.e. after
// we imported the symbols and satisfied undefined references
// to it. We can't just change linkage here because otherwise
// the IRMover will just rename the symbol.
if (GV && shouldInternalize(Used, S, GV))
InternalizedSyms.insert(GV->getName());
// At this point we know that either the combined LTO object will provide a
// definition of a symbol, or we will internalize it. In either case, we
// need to undefine the symbol. In the former case, the real definition
// needs to be able to replace the original definition without conflicting.
// In the latter case, we need to allow the combined LTO object to provide a
// definition with the same name, for example when doing parallel codegen.
undefine(S);
if (!GV)
// Module asm symbol.
continue;
switch (GV->getLinkage()) {
default:
break;
case llvm::GlobalValue::LinkOnceAnyLinkage:
GV->setLinkage(GlobalValue::WeakAnyLinkage);
break;
case llvm::GlobalValue::LinkOnceODRLinkage:
GV->setLinkage(GlobalValue::WeakODRLinkage);
break;
}
Keep.push_back(GV);
}
if (Error E = Mover.move(Obj->takeModule(), Keep,
[](GlobalValue &, IRMover::ValueAdder) {})) {
handleAllErrors(std::move(E), [&](const llvm::ErrorInfoBase &EIB) {
fatal("failed to link module " + F.getName() + ": " + EIB.message());
});
}
}
