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llvm-project/lld/ELF/SymbolTable.cpp

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//===- SymbolTable.cpp ----------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Symbol table is a bag of all known symbols. We put all symbols of
// all input files to the symbol table. The symbol table is basically
// a hash table with the logic to resolve symbol name conflicts using
// the symbol types.
//
//===----------------------------------------------------------------------===//
#include "SymbolTable.h"
#include "Config.h"
#include "LinkerScript.h"
#include "Symbols.h"
#include "SyntheticSections.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/Memory.h"
#include "lld/Common/Strings.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
using namespace llvm::object;
using namespace llvm::ELF;
using namespace lld;
using namespace lld::elf;
SymbolTable *elf::Symtab;
static InputFile *getFirstElf() {
if (!ObjectFiles.empty())
return ObjectFiles[0];
if (!SharedFiles.empty())
return SharedFiles[0];
return BitcodeFiles[0];
}
// All input object files must be for the same architecture
// (e.g. it does not make sense to link x86 object files with
// MIPS object files.) This function checks for that error.
static bool isCompatible(InputFile *F) {
if (!F->isElf() && !isa<BitcodeFile>(F))
return true;
if (F->EKind == Config->EKind && F->EMachine == Config->EMachine) {
if (Config->EMachine != EM_MIPS)
return true;
if (isMipsN32Abi(F) == Config->MipsN32Abi)
return true;
}
if (!Config->Emulation.empty())
error(toString(F) + " is incompatible with " + Config->Emulation);
else
error(toString(F) + " is incompatible with " + toString(getFirstElf()));
return false;
}
// Add symbols in File to the symbol table.
template <class ELFT> void SymbolTable::addFile(InputFile *File) {
if (!isCompatible(File))
return;
// Binary file
if (auto *F = dyn_cast<BinaryFile>(File)) {
BinaryFiles.push_back(F);
F->parse();
return;
}
// .a file
if (auto *F = dyn_cast<ArchiveFile>(File)) {
F->parse<ELFT>();
return;
}
// Lazy object file
if (auto *F = dyn_cast<LazyObjFile>(File)) {
LazyObjFiles.push_back(F);
F->parse<ELFT>();
return;
}
if (Config->Trace)
message(toString(File));
// .so file
if (auto *F = dyn_cast<SharedFile<ELFT>>(File)) {
// DSOs are uniquified not by filename but by soname.
F->parseSoName();
if (errorCount() || !SoNames.insert(F->SoName).second)
return;
SharedFiles.push_back(F);
F->parseRest();
return;
}
// LLVM bitcode file
if (auto *F = dyn_cast<BitcodeFile>(File)) {
BitcodeFiles.push_back(F);
F->parse<ELFT>(ComdatGroups);
return;
}
// Regular object file
ObjectFiles.push_back(File);
cast<ObjFile<ELFT>>(File)->parse(ComdatGroups);
}
// This function is where all the optimizations of link-time
// optimization happens. When LTO is in use, some input files are
// not in native object file format but in the LLVM bitcode format.
// This function compiles bitcode files into a few big native files
// using LLVM functions and replaces bitcode symbols with the results.
// Because all bitcode files that the program consists of are passed
// to the compiler at once, it can do whole-program optimization.
template <class ELFT> void SymbolTable::addCombinedLTOObject() {
if (BitcodeFiles.empty())
return;
// Compile bitcode files and replace bitcode symbols.
LTO.reset(new BitcodeCompiler);
for (BitcodeFile *F : BitcodeFiles)
LTO->add(*F);
for (InputFile *File : LTO->compile()) {
DenseSet<CachedHashStringRef> DummyGroups;
auto *Obj = cast<ObjFile<ELFT>>(File);
Obj->parse(DummyGroups);
for (Symbol *Sym : Obj->getGlobalSymbols())
Sym->parseSymbolVersion();
ObjectFiles.push_back(File);
}
}
Defined *SymbolTable::addAbsolute(StringRef Name, uint8_t Visibility,
uint8_t Binding) {
Symbol *Sym =
addRegular(Name, Visibility, STT_NOTYPE, 0, 0, Binding, nullptr, nullptr);
return cast<Defined>(Sym);
}
// Set a flag for --trace-symbol so that we can print out a log message
// if a new symbol with the same name is inserted into the symbol table.
void SymbolTable::trace(StringRef Name) {
SymMap.insert({CachedHashStringRef(Name), -1});
}
// Rename SYM as __wrap_SYM. The original symbol is preserved as __real_SYM.
// Used to implement --wrap.
template <class ELFT> void SymbolTable::addSymbolWrap(StringRef Name) {
Symbol *Sym = find(Name);
if (!Sym)
return;
// Do not wrap the same symbol twice.
for (const WrappedSymbol &S : WrappedSymbols)
if (S.Sym == Sym)
return;
Symbol *Real = addUndefined<ELFT>(Saver.save("__real_" + Name));
Symbol *Wrap = addUndefined<ELFT>(Saver.save("__wrap_" + Name));
WrappedSymbols.push_back({Sym, Real, Wrap});
// We want to tell LTO not to inline symbols to be overwritten
// because LTO doesn't know the final symbol contents after renaming.
Real->CanInline = false;
Sym->CanInline = false;
// Tell LTO not to eliminate these symbols.
Sym->IsUsedInRegularObj = true;
Wrap->IsUsedInRegularObj = true;
}
// Apply symbol renames created by -wrap. The renames are created
// before LTO in addSymbolWrap() to have a chance to inform LTO (if
// LTO is running) not to include these symbols in IPO. Now that the
// symbols are finalized, we can perform the replacement.
void SymbolTable::applySymbolWrap() {
// This function rotates 3 symbols:
//
// __real_sym becomes sym
// sym becomes __wrap_sym
// __wrap_sym becomes __real_sym
//
// The last part is special in that we don't want to change what references to
// __wrap_sym point to, we just want have __real_sym in the symbol table.
for (WrappedSymbol &W : WrappedSymbols) {
// First, make a copy of __real_sym.
Symbol *Real = nullptr;
if (W.Real->isDefined()) {
Real = reinterpret_cast<Symbol *>(make<SymbolUnion>());
memcpy(Real, W.Real, sizeof(SymbolUnion));
}
// Replace __real_sym with sym and sym with __wrap_sym.
memcpy(W.Real, W.Sym, sizeof(SymbolUnion));
memcpy(W.Sym, W.Wrap, sizeof(SymbolUnion));
// We now have two copies of __wrap_sym. Drop one.
W.Wrap->IsUsedInRegularObj = false;
if (Real)
SymVector.push_back(Real);
}
}
// Apply changes caused by relocations to wrapped symbols
// This is needed for direct calls to __wrap_sym
void SymbolTable::applySymbolWrapReloc() {
for (WrappedSymbol &W : WrappedSymbols) {
memcpy(W.Wrap, W.Sym, sizeof(SymbolUnion));
// Keep this so that this copy of the symbol remains dropped
W.Wrap->IsUsedInRegularObj = false;
}
}
static uint8_t getMinVisibility(uint8_t VA, uint8_t VB) {
if (VA == STV_DEFAULT)
return VB;
if (VB == STV_DEFAULT)
return VA;
return std::min(VA, VB);
}
// Find an existing symbol or create and insert a new one.
std::pair<Symbol *, bool> SymbolTable::insert(StringRef Name) {
// <name>@@<version> means the symbol is the default version. In that
// case <name>@@<version> will be used to resolve references to <name>.
//
// Since this is a hot path, the following string search code is
// optimized for speed. StringRef::find(char) is much faster than
// StringRef::find(StringRef).
size_t Pos = Name.find('@');
if (Pos != StringRef::npos && Pos + 1 < Name.size() && Name[Pos + 1] == '@')
Name = Name.take_front(Pos);
auto P = SymMap.insert({CachedHashStringRef(Name), (int)SymVector.size()});
int &SymIndex = P.first->second;
bool IsNew = P.second;
bool Traced = false;
if (SymIndex == -1) {
SymIndex = SymVector.size();
IsNew = Traced = true;
}
Symbol *Sym;
if (IsNew) {
Sym = reinterpret_cast<Symbol *>(make<SymbolUnion>());
Sym->Visibility = STV_DEFAULT;
Sym->IsUsedInRegularObj = false;
Sym->ExportDynamic = false;
Sym->CanInline = true;
Sym->Traced = Traced;
Sym->VersionId = Config->DefaultSymbolVersion;
SymVector.push_back(Sym);
} else {
Sym = SymVector[SymIndex];
}
return {Sym, IsNew};
}
// Find an existing symbol or create and insert a new one, then apply the given
// attributes.
std::pair<Symbol *, bool> SymbolTable::insert(StringRef Name, uint8_t Type,
uint8_t Visibility,
bool CanOmitFromDynSym,
InputFile *File) {
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 (!File || File->kind() == InputFile::ObjKind)
S->IsUsedInRegularObj = true;
if (!WasInserted && S->Type != Symbol::UnknownType &&
((Type == STT_TLS) != S->isTls())) {
error("TLS attribute mismatch: " + toString(*S) + "\n>>> defined in " +
toString(S->File) + "\n>>> defined in " + toString(File));
}
return {S, WasInserted};
}
template <class ELFT> Symbol *SymbolTable::addUndefined(StringRef Name) {
return addUndefined<ELFT>(Name, STB_GLOBAL, STV_DEFAULT,
/*Type*/ 0,
/*CanOmitFromDynSym*/ false, /*File*/ nullptr);
}
static uint8_t getVisibility(uint8_t StOther) { return StOther & 3; }
template <class ELFT>
Symbol *SymbolTable::addUndefined(StringRef Name, uint8_t Binding,
uint8_t StOther, uint8_t Type,
bool CanOmitFromDynSym, InputFile *File) {
Symbol *S;
bool WasInserted;
uint8_t Visibility = getVisibility(StOther);
std::tie(S, WasInserted) =
insert(Name, Type, Visibility, CanOmitFromDynSym, File);
// An undefined symbol with non default visibility must be satisfied
// in the same DSO.
if (WasInserted || (isa<SharedSymbol>(S) && Visibility != STV_DEFAULT)) {
replaceSymbol<Undefined>(S, File, Name, Binding, StOther, Type);
return S;
}
if (S->isShared() || S->isLazy() || (S->isUndefined() && Binding != STB_WEAK))
S->Binding = Binding;
if (!Config->GcSections && Binding != STB_WEAK)
if (auto *SS = dyn_cast<SharedSymbol>(S))
SS->getFile<ELFT>().IsNeeded = true;
if (S->isLazy()) {
// An undefined weak will not fetch archive members. See comment on Lazy in
// Symbols.h for the details.
if (Binding == STB_WEAK) {
S->Type = Type;
return S;
}
// Do extra check for --warn-backrefs.
//
// --warn-backrefs is an option to prevent an undefined reference from
// fetching an archive member written earlier in the command line. It can be
// used to keep compatibility with GNU linkers to some degree.
// I'll explain the feature and why you may find it useful in this comment.
//
// lld's symbol resolution semantics is more relaxed than traditional Unix
// linkers. For example,
//
// ld.lld foo.a bar.o
//
// succeeds even if bar.o contains an undefined symbol that has to be
// resolved by some object file in foo.a. Traditional Unix linkers don't
// allow this kind of backward reference, as they visit each file only once
// from left to right in the command line while resolving all undefined
// symbols at the moment of visiting.
//
// In the above case, since there's no undefined symbol when a linker visits
// foo.a, no files are pulled out from foo.a, and because the linker forgets
// about foo.a after visiting, it can't resolve undefined symbols in bar.o
// that could have been resolved otherwise.
//
// That lld accepts more relaxed form means that (besides it'd make more
// sense) you can accidentally write a command line or a build file that
// works only with lld, even if you have a plan to distribute it to wider
// users who may be using GNU linkers. With --warn-backrefs, you can detect
// a library order that doesn't work with other Unix linkers.
//
// The option is also useful to detect cyclic dependencies between static
// archives. Again, lld accepts
//
// ld.lld foo.a bar.a
//
// even if foo.a and bar.a depend on each other. With --warn-backrefs, it is
// handled as an error.
//
// Here is how the option works. We assign a group ID to each file. A file
// with a smaller group ID can pull out object files from an archive file
// with an equal or greater group ID. Otherwise, it is a reverse dependency
// and an error.
//
// A file outside --{start,end}-group gets a fresh ID when instantiated. All
// files within the same --{start,end}-group get the same group ID. E.g.
//
// ld.lld A B --start-group C D --end-group E
//
// A forms group 0. B form group 1. C and D (including their member object
// files) form group 2. E forms group 3. I think that you can see how this
// group assignment rule simulates the traditional linker's semantics.
bool Backref =
Config->WarnBackrefs && File && S->File->GroupId < File->GroupId;
fetchLazy<ELFT>(S);
// We don't report backward references to weak symbols as they can be
// overridden later.
if (Backref && S->Binding != STB_WEAK)
warn("backward reference detected: " + Name + " in " + toString(File) +
" refers to " + toString(S->File));
}
return S;
}
// Using .symver foo,foo@@VER unfortunately creates two symbols: foo and
// foo@@VER. We want to effectively ignore foo, so give precedence to
// foo@@VER.
// FIXME: If users can transition to using
// .symver foo,foo@@@VER
// we can delete this hack.
static int compareVersion(Symbol *S, StringRef Name) {
bool A = Name.contains("@@");
bool B = S->getName().contains("@@");
if (A && !B)
return 1;
if (!A && B)
return -1;
return 0;
}
// We have a new defined symbol with the specified binding. Return 1 if the new
// symbol should win, -1 if the new symbol should lose, or 0 if both symbols are
// strong defined symbols.
static int compareDefined(Symbol *S, bool WasInserted, uint8_t Binding,
StringRef Name) {
if (WasInserted)
return 1;
if (!S->isDefined())
return 1;
if (int R = compareVersion(S, Name))
return R;
if (Binding == STB_WEAK)
return -1;
if (S->isWeak())
return 1;
return 0;
}
// We have a new non-common defined symbol with the specified binding. Return 1
// if the new symbol should win, -1 if the new symbol should lose, or 0 if there
// is a conflict. If the new symbol wins, also update the binding.
static int compareDefinedNonCommon(Symbol *S, bool WasInserted, uint8_t Binding,
bool IsAbsolute, uint64_t Value,
StringRef Name) {
if (int Cmp = compareDefined(S, WasInserted, Binding, Name))
return Cmp;
if (auto *R = dyn_cast<Defined>(S)) {
if (R->Section && isa<BssSection>(R->Section)) {
// Non-common symbols take precedence over common symbols.
if (Config->WarnCommon)
warn("common " + S->getName() + " is overridden");
return 1;
}
if (R->Section == nullptr && Binding == STB_GLOBAL && IsAbsolute &&
R->Value == Value)
return -1;
}
return 0;
}
Symbol *SymbolTable::addCommon(StringRef N, uint64_t Size, uint32_t Alignment,
uint8_t Binding, uint8_t StOther, uint8_t Type,
InputFile &File) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(N, Type, getVisibility(StOther),
/*CanOmitFromDynSym*/ false, &File);
int Cmp = compareDefined(S, WasInserted, Binding, N);
if (Cmp < 0)
return S;
if (Cmp > 0) {
auto *Bss = make<BssSection>("COMMON", Size, Alignment);
Bss->File = &File;
Bss->Live = !Config->GcSections;
InputSections.push_back(Bss);
replaceSymbol<Defined>(S, &File, N, Binding, StOther, Type, 0, Size, Bss);
return S;
}
auto *D = cast<Defined>(S);
auto *Bss = dyn_cast_or_null<BssSection>(D->Section);
if (!Bss) {
// Non-common symbols take precedence over common symbols.
if (Config->WarnCommon)
warn("common " + S->getName() + " is overridden");
return S;
}
if (Config->WarnCommon)
warn("multiple common of " + D->getName());
Bss->Alignment = std::max(Bss->Alignment, Alignment);
if (Size > Bss->Size) {
D->File = Bss->File = &File;
D->Size = Bss->Size = Size;
}
return S;
}
static void reportDuplicate(Symbol *Sym, InputFile *NewFile) {
if (!Config->AllowMultipleDefinition)
error("duplicate symbol: " + toString(*Sym) + "\n>>> defined in " +
toString(Sym->File) + "\n>>> defined in " + toString(NewFile));
}
static void reportDuplicate(Symbol *Sym, InputFile *NewFile,
InputSectionBase *ErrSec, uint64_t ErrOffset) {
if (Config->AllowMultipleDefinition)
return;
Defined *D = cast<Defined>(Sym);
if (!D->Section || !ErrSec) {
reportDuplicate(Sym, NewFile);
return;
}
// Construct and print an error message in the form of:
//
// ld.lld: error: duplicate symbol: foo
// >>> defined at bar.c:30
// >>> bar.o (/home/alice/src/bar.o)
// >>> defined at baz.c:563
// >>> baz.o in archive libbaz.a
auto *Sec1 = cast<InputSectionBase>(D->Section);
std::string Src1 = Sec1->getSrcMsg(*Sym, D->Value);
std::string Obj1 = Sec1->getObjMsg(D->Value);
std::string Src2 = ErrSec->getSrcMsg(*Sym, ErrOffset);
std::string Obj2 = ErrSec->getObjMsg(ErrOffset);
std::string Msg = "duplicate symbol: " + toString(*Sym) + "\n>>> defined at ";
if (!Src1.empty())
Msg += Src1 + "\n>>> ";
Msg += Obj1 + "\n>>> defined at ";
if (!Src2.empty())
Msg += Src2 + "\n>>> ";
Msg += Obj2;
error(Msg);
}
Symbol *SymbolTable::addRegular(StringRef Name, uint8_t StOther, uint8_t Type,
uint64_t Value, uint64_t Size, uint8_t Binding,
SectionBase *Section, InputFile *File) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = insert(Name, Type, getVisibility(StOther),
/*CanOmitFromDynSym*/ false, File);
int Cmp = compareDefinedNonCommon(S, WasInserted, Binding, Section == nullptr,
Value, Name);
if (Cmp > 0)
replaceSymbol<Defined>(S, File, Name, Binding, StOther, Type, Value, Size,
Section);
else if (Cmp == 0)
reportDuplicate(S, File, dyn_cast_or_null<InputSectionBase>(Section),
Value);
return S;
}
template <typename ELFT>
void SymbolTable::addShared(StringRef Name, SharedFile<ELFT> &File,
const typename ELFT::Sym &Sym, uint32_t Alignment,
uint32_t VerdefIndex) {
// 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, &File);
// Make sure we preempt DSO symbols with default visibility.
if (Sym.getVisibility() == STV_DEFAULT)
S->ExportDynamic = true;
// An undefined symbol with non default visibility must be satisfied
// in the same DSO.
if (WasInserted ||
((S->isUndefined() || S->isLazy()) && S->Visibility == STV_DEFAULT)) {
uint8_t Binding = S->Binding;
bool WasUndefined = S->isUndefined();
replaceSymbol<SharedSymbol>(S, File, Name, Sym.getBinding(), Sym.st_other,
Sym.getType(), Sym.st_value, Sym.st_size,
Alignment, VerdefIndex);
if (!WasInserted) {
S->Binding = Binding;
if (!S->isWeak() && !Config->GcSections && WasUndefined)
File.IsNeeded = true;
}
}
}
Symbol *SymbolTable::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(S, WasInserted, Binding,
/*IsAbs*/ false, /*Value*/ 0, Name);
if (Cmp > 0)
replaceSymbol<Defined>(S, &F, Name, Binding, StOther, Type, 0, 0, nullptr);
else if (Cmp == 0)
reportDuplicate(S, &F);
return S;
}
Symbol *SymbolTable::find(StringRef Name) {
auto It = SymMap.find(CachedHashStringRef(Name));
if (It == SymMap.end())
return nullptr;
if (It->second == -1)
return nullptr;
return SymVector[It->second];
}
// This is used to handle lazy symbols. May replace existent
// symbol with lazy version or request to Fetch it.
template <class ELFT, typename LazyT, typename... ArgT>
static void replaceOrFetchLazy(StringRef Name, InputFile &File,
llvm::function_ref<InputFile *()> Fetch,
ArgT &&... Arg) {
Symbol *S;
bool WasInserted;
std::tie(S, WasInserted) = Symtab->insert(Name);
if (WasInserted) {
replaceSymbol<LazyT>(S, File, Symbol::UnknownType,
std::forward<ArgT>(Arg)...);
return;
}
if (!S->isUndefined())
return;
// An undefined weak will not fetch archive members. See comment on Lazy in
// Symbols.h for the details.
if (S->isWeak()) {
replaceSymbol<LazyT>(S, File, S->Type, std::forward<ArgT>(Arg)...);
S->Binding = STB_WEAK;
return;
}
if (InputFile *F = Fetch())
Symtab->addFile<ELFT>(F);
}
template <class ELFT>
void SymbolTable::addLazyArchive(StringRef Name, ArchiveFile &F,
const object::Archive::Symbol Sym) {
replaceOrFetchLazy<ELFT, LazyArchive>(Name, F, [&]() { return F.fetch(Sym); },
Sym);
}
template <class ELFT>
void SymbolTable::addLazyObject(StringRef Name, LazyObjFile &Obj) {
replaceOrFetchLazy<ELFT, LazyObject>(Name, Obj, [&]() { return Obj.fetch(); },
Name);
}
template <class ELFT> void SymbolTable::fetchLazy(Symbol *Sym) {
if (auto *S = dyn_cast<LazyArchive>(Sym)) {
if (InputFile *File = S->fetch())
addFile<ELFT>(File);
return;
}
auto *S = cast<LazyObject>(Sym);
if (InputFile *File = cast<LazyObjFile>(S->File)->fetch())
addFile<ELFT>(File);
}
// Initialize DemangledSyms with a map from demangled symbols to symbol
// objects. Used to handle "extern C++" directive in version scripts.
//
// The map will contain all demangled symbols. That can be very large,
// and in LLD we generally want to avoid do anything for each symbol.
// Then, why are we doing this? Here's why.
//
// Users can use "extern C++ {}" directive to match against demangled
// C++ symbols. For example, you can write a pattern such as
// "llvm::*::foo(int, ?)". Obviously, there's no way to handle this
// other than trying to match a pattern against all demangled symbols.
// So, if "extern C++" feature is used, we need to demangle all known
// symbols.
StringMap<std::vector<Symbol *>> &SymbolTable::getDemangledSyms() {
if (!DemangledSyms) {
DemangledSyms.emplace();
for (Symbol *Sym : SymVector) {
if (!Sym->isDefined())
continue;
if (Optional<std::string> S = demangleItanium(Sym->getName()))
(*DemangledSyms)[*S].push_back(Sym);
else
(*DemangledSyms)[Sym->getName()].push_back(Sym);
}
}
return *DemangledSyms;
}
std::vector<Symbol *> SymbolTable::findByVersion(SymbolVersion Ver) {
if (Ver.IsExternCpp)
return getDemangledSyms().lookup(Ver.Name);
if (Symbol *B = find(Ver.Name))
if (B->isDefined())
return {B};
return {};
}
std::vector<Symbol *> SymbolTable::findAllByVersion(SymbolVersion Ver) {
std::vector<Symbol *> Res;
StringMatcher M(Ver.Name);
if (Ver.IsExternCpp) {
for (auto &P : getDemangledSyms())
if (M.match(P.first()))
Res.insert(Res.end(), P.second.begin(), P.second.end());
return Res;
}
for (Symbol *Sym : SymVector)
if (Sym->isDefined() && M.match(Sym->getName()))
Res.push_back(Sym);
return Res;
}
// If there's only one anonymous version definition in a version
// script file, the script does not actually define any symbol version,
// but just specifies symbols visibilities.
void SymbolTable::handleAnonymousVersion() {
for (SymbolVersion &Ver : Config->VersionScriptGlobals)
assignExactVersion(Ver, VER_NDX_GLOBAL, "global");
for (SymbolVersion &Ver : Config->VersionScriptGlobals)
assignWildcardVersion(Ver, VER_NDX_GLOBAL);
for (SymbolVersion &Ver : Config->VersionScriptLocals)
assignExactVersion(Ver, VER_NDX_LOCAL, "local");
for (SymbolVersion &Ver : Config->VersionScriptLocals)
assignWildcardVersion(Ver, VER_NDX_LOCAL);
}
// Handles -dynamic-list.
void SymbolTable::handleDynamicList() {
for (SymbolVersion &Ver : Config->DynamicList) {
std::vector<Symbol *> Syms;
if (Ver.HasWildcard)
Syms = findAllByVersion(Ver);
else
Syms = findByVersion(Ver);
for (Symbol *B : Syms) {
if (!Config->Shared)
B->ExportDynamic = true;
else if (B->includeInDynsym())
B->IsPreemptible = true;
}
}
}
// Set symbol versions to symbols. This function handles patterns
// containing no wildcard characters.
void SymbolTable::assignExactVersion(SymbolVersion Ver, uint16_t VersionId,
StringRef VersionName) {
if (Ver.HasWildcard)
return;
// Get a list of symbols which we need to assign the version to.
std::vector<Symbol *> Syms = findByVersion(Ver);
if (Syms.empty()) {
if (!Config->UndefinedVersion)
error("version script assignment of '" + VersionName + "' to symbol '" +
Ver.Name + "' failed: symbol not defined");
return;
}
// Assign the version.
for (Symbol *Sym : Syms) {
// Skip symbols containing version info because symbol versions
// specified by symbol names take precedence over version scripts.
// See parseSymbolVersion().
if (Sym->getName().contains('@'))
continue;
if (Sym->VersionId != Config->DefaultSymbolVersion &&
Sym->VersionId != VersionId)
error("duplicate symbol '" + Ver.Name + "' in version script");
Sym->VersionId = VersionId;
}
}
void SymbolTable::assignWildcardVersion(SymbolVersion Ver, uint16_t VersionId) {
if (!Ver.HasWildcard)
return;
// Exact matching takes precendence over fuzzy matching,
// so we set a version to a symbol only if no version has been assigned
// to the symbol. This behavior is compatible with GNU.
for (Symbol *B : findAllByVersion(Ver))
if (B->VersionId == Config->DefaultSymbolVersion)
B->VersionId = VersionId;
}
// This function processes version scripts by updating VersionId
// member of symbols.
void SymbolTable::scanVersionScript() {
// Handle edge cases first.
handleAnonymousVersion();
handleDynamicList();
// Now we have version definitions, so we need to set version ids to symbols.
// Each version definition has a glob pattern, and all symbols that match
// with the pattern get that version.
// First, we assign versions to exact matching symbols,
// i.e. version definitions not containing any glob meta-characters.
for (VersionDefinition &V : Config->VersionDefinitions)
for (SymbolVersion &Ver : V.Globals)
assignExactVersion(Ver, V.Id, V.Name);
// Next, we assign versions to fuzzy matching symbols,
// i.e. version definitions containing glob meta-characters.
// Note that because the last match takes precedence over previous matches,
// we iterate over the definitions in the reverse order.
for (VersionDefinition &V : llvm::reverse(Config->VersionDefinitions))
for (SymbolVersion &Ver : V.Globals)
assignWildcardVersion(Ver, V.Id);
// Symbol themselves might know their versions because symbols
// can contain versions in the form of <name>@<version>.
// Let them parse and update their names to exclude version suffix.
for (Symbol *Sym : SymVector)
Sym->parseSymbolVersion();
}
template void SymbolTable::addFile<ELF32LE>(InputFile *);
template void SymbolTable::addFile<ELF32BE>(InputFile *);
template void SymbolTable::addFile<ELF64LE>(InputFile *);
template void SymbolTable::addFile<ELF64BE>(InputFile *);
template void SymbolTable::addSymbolWrap<ELF32LE>(StringRef);
template void SymbolTable::addSymbolWrap<ELF32BE>(StringRef);
template void SymbolTable::addSymbolWrap<ELF64LE>(StringRef);
template void SymbolTable::addSymbolWrap<ELF64BE>(StringRef);
template Symbol *SymbolTable::addUndefined<ELF32LE>(StringRef);
template Symbol *SymbolTable::addUndefined<ELF32BE>(StringRef);
template Symbol *SymbolTable::addUndefined<ELF64LE>(StringRef);
template Symbol *SymbolTable::addUndefined<ELF64BE>(StringRef);
template Symbol *SymbolTable::addUndefined<ELF32LE>(StringRef, uint8_t, uint8_t,
uint8_t, bool, InputFile *);
template Symbol *SymbolTable::addUndefined<ELF32BE>(StringRef, uint8_t, uint8_t,
uint8_t, bool, InputFile *);
template Symbol *SymbolTable::addUndefined<ELF64LE>(StringRef, uint8_t, uint8_t,
uint8_t, bool, InputFile *);
template Symbol *SymbolTable::addUndefined<ELF64BE>(StringRef, uint8_t, uint8_t,
uint8_t, bool, InputFile *);
template void SymbolTable::addCombinedLTOObject<ELF32LE>();
template void SymbolTable::addCombinedLTOObject<ELF32BE>();
template void SymbolTable::addCombinedLTOObject<ELF64LE>();
template void SymbolTable::addCombinedLTOObject<ELF64BE>();
template void
SymbolTable::addLazyArchive<ELF32LE>(StringRef, ArchiveFile &,
const object::Archive::Symbol);
template void
SymbolTable::addLazyArchive<ELF32BE>(StringRef, ArchiveFile &,
const object::Archive::Symbol);
template void
SymbolTable::addLazyArchive<ELF64LE>(StringRef, ArchiveFile &,
const object::Archive::Symbol);
template void
SymbolTable::addLazyArchive<ELF64BE>(StringRef, ArchiveFile &,
const object::Archive::Symbol);
template void SymbolTable::addLazyObject<ELF32LE>(StringRef, LazyObjFile &);
template void SymbolTable::addLazyObject<ELF32BE>(StringRef, LazyObjFile &);
template void SymbolTable::addLazyObject<ELF64LE>(StringRef, LazyObjFile &);
template void SymbolTable::addLazyObject<ELF64BE>(StringRef, LazyObjFile &);
template void SymbolTable::fetchLazy<ELF32LE>(Symbol *);
template void SymbolTable::fetchLazy<ELF32BE>(Symbol *);
template void SymbolTable::fetchLazy<ELF64LE>(Symbol *);
template void SymbolTable::fetchLazy<ELF64BE>(Symbol *);
template void SymbolTable::addShared<ELF32LE>(StringRef, SharedFile<ELF32LE> &,
const typename ELF32LE::Sym &,
uint32_t Alignment, uint32_t);
template void SymbolTable::addShared<ELF32BE>(StringRef, SharedFile<ELF32BE> &,
const typename ELF32BE::Sym &,
uint32_t Alignment, uint32_t);
template void SymbolTable::addShared<ELF64LE>(StringRef, SharedFile<ELF64LE> &,
const typename ELF64LE::Sym &,
uint32_t Alignment, uint32_t);
template void SymbolTable::addShared<ELF64BE>(StringRef, SharedFile<ELF64BE> &,
const typename ELF64BE::Sym &,
uint32_t Alignment, uint32_t);
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