blob: c5808a89bf57f78518b9cb6a51908a147bb131c7 [file] [log] [blame]
//===- SymbolTable.cpp ----------------------------------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#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"
using namespace llvm;
using namespace lld;
using namespace lld::macho;
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,
const InputFile *file) {
auto p = symMap.insert({CachedHashStringRef(name), (int)symVector.size()});
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>());
sym->isUsedInRegularObj |= !file || isa<ObjFile>(file);
return {sym, p.second};
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, file);
assert(!isWeakDef || (isa<BitcodeFile>(file) && !isec) ||
(isa<ObjFile>(file) && file == isec->getFile()));
if (!wasInserted) {
if (auto *defined = dyn_cast<Defined>(s)) {
if (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;
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 + "\n>>> defined in " +
toString(defined->getFile()) + "\n>>> defined in " +
} else if (auto *dysym = dyn_cast<DylibSymbol>(s)) {
overridesWeakDef = !isWeakDef && dysym->isWeakDef();
// 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, file, isec, value, size, isWeakDef, /*isExternal=*/true,
isPrivateExtern, isThumb, isReferencedDynamically, noDeadStrip);
defined->overridesWeakDef = overridesWeakDef;
return defined;
Symbol *SymbolTable::addUndefined(StringRef name, InputFile *file,
bool isWeakRef) {
Symbol *s;
bool wasInserted;
std::tie(s, wasInserted) = insert(name, file);
RefState refState = isWeakRef ? RefState::Weak : RefState::Strong;
if (wasInserted)
replaceSymbol<Undefined>(s, name, file, refState);
else if (auto *lazy = dyn_cast<LazySymbol>(s))
else if (auto *dynsym = dyn_cast<DylibSymbol>(s))
else if (auto *undefined = dyn_cast<Undefined>(s))
undefined->refState = std::max(undefined->refState, refState);
return s;
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, file);
if (!wasInserted) {
if (auto *common = dyn_cast<CommonSymbol>(s)) {
if (size < common->size)
return s;
} else if (isa<Defined>(s)) {
return s;
// Common symbols take priority over all non-Defined symbols, so in case of
// a name conflict, we fall through to the replaceSymbol() call below.
replaceSymbol<CommonSymbol>(s, name, file, size, align, isPrivateExtern);
return s;
Symbol *SymbolTable::addDylib(StringRef name, DylibFile *file, bool isWeakDef,
bool isTlv) {
Symbol *s;
bool wasInserted;
std::tie(s, wasInserted) = insert(name, file);
RefState refState = RefState::Unreferenced;
if (!wasInserted) {
if (auto *defined = dyn_cast<Defined>(s)) {
if (isWeakDef && !defined->isWeakDef())
defined->overridesWeakDef = true;
} else if (auto *undefined = dyn_cast<Undefined>(s)) {
refState = undefined->refState;
} else if (auto *dysym = dyn_cast<DylibSymbol>(s)) {
refState = dysym->getRefState();
bool isDynamicLookup = file == nullptr;
if (wasInserted || isa<Undefined>(s) ||
(isa<DylibSymbol>(s) &&
((!isWeakDef && s->isWeakDef()) ||
(!isDynamicLookup && cast<DylibSymbol>(s)->isDynamicLookup())))) {
if (auto *dynsym = dyn_cast<DylibSymbol>(s))
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, file);
if (wasInserted)
replaceSymbol<LazySymbol>(s, file, sym);
else if (isa<Undefined>(s) || (isa<DylibSymbol>(s) && s->isWeakDef()))
return s;
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,
s->includeInSymtab = includeInSymtab;
return s;
enum class Boundary {
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('$');
// Attach the symbol to any InputSection that will end up in the right
// OutputSection -- it doesn't matter which one we pick.
// Don't bother looking through inputSections for a matching
// ConcatInputSection -- we need to create ConcatInputSection for
// non-existing sections anyways, and that codepath works even if we should
// already have a ConcatInputSection with the right name.
OutputSection *osec = nullptr;
// This looks for __TEXT,__cstring etc.
for (SyntheticSection *ssec : syntheticSections)
if (ssec->segname == segName && ssec->name == sectName) {
osec = ssec->isec->parent;
if (!osec) {
ConcatInputSection *isec = make<ConcatInputSection>(segName, sectName);
// This runs after markLive() and is only called for Undefineds that are
// live. Marking the isec live ensures an OutputSection is created that the
// start/end symbol can refer to.
isec->live = true;
// This runs after gatherInputSections(), so need to explicitly set parent
// and add to inputSections.
osec = isec->parent = ConcatOutputSection::getOrCreateForInput(isec);
if (which == Boundary::Start)
static void handleSegmentBoundarySymbol(const Undefined &sym, StringRef segName,
Boundary which) {
OutputSegment *seg = getOrCreateOutputSegment(segName);
if (which == Boundary::Start)
void lld::macho::treatUndefinedSymbol(const Undefined &sym, StringRef source) {
// Handle start/end symbols.
StringRef name = sym.getName();
if (name.consume_front("section$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())) {
// 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();
message += "\n>>> referenced by " + toString(sym.getFile());
return message;
switch (config->undefinedSymbolTreatment) {
case UndefinedSymbolTreatment::error:
case UndefinedSymbolTreatment::warning:
case UndefinedSymbolTreatment::dynamic_lookup:
case UndefinedSymbolTreatment::suppress:
case UndefinedSymbolTreatment::unknown:
llvm_unreachable("unknown -undefined TREATMENT");
SymbolTable *macho::symtab;