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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 "Error.h"
#include "LinkerScript.h"
#include "Memory.h"
#include "Symbols.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
using namespace llvm::object;
using namespace llvm::ELF;
using namespace lld;
using namespace lld::elf;
// 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.
template <class ELFT> static bool isCompatible(InputFile *F) {
if (!isa<ELFFileBase<ELFT>>(F) && !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(Config->FirstElf));
return false;
}
// Add symbols in File to the symbol table.
template <class ELFT> void SymbolTable<ELFT>::addFile(InputFile *File) {
if (!Config->FirstElf && isa<ELFFileBase<ELFT>>(File))
Config->FirstElf = File;
if (!isCompatible<ELFT>(File))
return;
// Binary file
if (auto *F = dyn_cast<BinaryFile>(File)) {
BinaryFiles.push_back(F);
F->parse<ELFT>();
return;
}
// .a file
if (auto *F = dyn_cast<ArchiveFile>(File)) {
F->parse<ELFT>();
return;
}
// Lazy object file
if (auto *F = dyn_cast<LazyObjectFile>(File)) {
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
auto *F = cast<ObjectFile<ELFT>>(File);
ObjectFiles.push_back(F);
F->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 consist of a program are passed
// to the compiler at once, it can do whole-program optimization.
template <class ELFT> void SymbolTable<ELFT>::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()) {
ObjectFile<ELFT> *Obj = cast<ObjectFile<ELFT>>(File);
DenseSet<CachedHashStringRef> DummyGroups;
Obj->parse(DummyGroups);
ObjectFiles.push_back(Obj);
}
}
template <class ELFT>
DefinedRegular *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>(Sym->body());
}
// Add Name as an "ignored" symbol. An ignored symbol is a regular
// linker-synthesized defined symbol, but is only defined if needed.
template <class ELFT>
DefinedRegular *SymbolTable<ELFT>::addIgnored(StringRef Name,
uint8_t Visibility) {
SymbolBody *S = find(Name);
if (!S || S->isInCurrentDSO())
return nullptr;
return addAbsolute(Name, Visibility);
}
// 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.
template <class ELFT> void SymbolTable<ELFT>::trace(StringRef Name) {
Symtab.insert({CachedHashStringRef(Name), {-1, true}});
}
// Rename SYM as __wrap_SYM. The original symbol is preserved as __real_SYM.
// Used to implement --wrap.
template <class ELFT> void SymbolTable<ELFT>::addSymbolWrap(StringRef Name) {
SymbolBody *B = find(Name);
if (!B)
return;
Symbol *Sym = B->symbol();
Symbol *Real = addUndefined(Saver.save("__real_" + Name));
Symbol *Wrap = addUndefined(Saver.save("__wrap_" + Name));
// Tell LTO not to eliminate this symbol
Wrap->IsUsedInRegularObj = true;
Config->RenamedSymbols[Real] = {Sym, Real->Binding};
Config->RenamedSymbols[Sym] = {Wrap, Sym->Binding};
}
// Creates alias for symbol. Used to implement --defsym=ALIAS=SYM.
template <class ELFT> void SymbolTable<ELFT>::addSymbolAlias(StringRef Alias,
StringRef Name) {
SymbolBody *B = find(Name);
if (!B) {
error("-defsym: undefined symbol: " + Name);
return;
}
Symbol *Sym = B->symbol();
Symbol *AliasSym = addUndefined(Alias);
// Tell LTO not to eliminate this symbol
Sym->IsUsedInRegularObj = true;
Config->RenamedSymbols[AliasSym] = {Sym, AliasSym->Binding};
}
// Apply symbol renames created by -wrap and -defsym. The renames are created
// before LTO in addSymbolWrap() and addSymbolAlias() 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.
template <class ELFT> void SymbolTable<ELFT>::applySymbolRenames() {
for (auto &KV : Config->RenamedSymbols) {
Symbol *Dst = KV.first;
Symbol *Src = KV.second.Target;
Dst->body()->copy(Src->body());
Dst->Binding = KV.second.OriginalBinding;
}
}
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.
template <class ELFT>
std::pair<Symbol *, bool> SymbolTable<ELFT>::insert(StringRef Name) {
// <name>@@<version> means the symbol is the default version. In that
// case symbol <name> must exist and <name>@@<version> will be used to
// resolve references to <name>.
size_t Pos = Name.find("@@");
if (Pos != StringRef::npos)
Name = Name.take_front(Pos);
auto P = Symtab.insert(
{CachedHashStringRef(Name), SymIndex((int)SymVector.size(), false)});
SymIndex &V = P.first->second;
bool IsNew = P.second;
if (V.Idx == -1) {
IsNew = true;
V = SymIndex((int)SymVector.size(), true);
}
Symbol *Sym;
if (IsNew) {
Sym = make<Symbol>();
Sym->InVersionScript = false;
Sym->Binding = STB_WEAK;
Sym->Visibility = STV_DEFAULT;
Sym->IsUsedInRegularObj = false;
Sym->ExportDynamic = false;
Sym->Traced = V.Traced;
Sym->VersionId = Config->DefaultSymbolVersion;
SymVector.push_back(Sym);
} else {
Sym = SymVector[V.Idx];
}
return {Sym, IsNew};
}
// Find an existing symbol or create and insert a new one, then apply the given
// attributes.
template <class ELFT>
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: " + toString(*S->body()) +
"\n>>> defined in " + toString(S->body()->File) +
"\n>>> defined in " + toString(File));
}
return {S, WasInserted};
}
template <class ELFT> Symbol *SymbolTable<ELFT>::addUndefined(StringRef Name) {
return addUndefined(Name, /*IsLocal=*/false, 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<ELFT>::addUndefined(StringRef Name, bool IsLocal,
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->body()) && Visibility != STV_DEFAULT)) {
S->Binding = Binding;
replaceBody<Undefined>(S, Name, IsLocal, StOther, Type, File);
return S;
}
if (Binding != STB_WEAK) {
SymbolBody *B = S->body();
if (B->isShared() || B->isLazy() || B->isUndefined())
S->Binding = Binding;
if (auto *SS = dyn_cast<SharedSymbol>(B))
cast<SharedFile<ELFT>>(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 (InputFile *F = L->fetch())
addFile(F);
}
return S;
}
// 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) {
if (WasInserted)
return 1;
SymbolBody *Body = S->body();
if (!Body->isInCurrentDSO())
return 1;
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.
template <typename ELFT>
static int compareDefinedNonCommon(Symbol *S, bool WasInserted, uint8_t Binding,
bool IsAbsolute, typename ELFT::uint Value) {
if (int Cmp = compareDefined(S, WasInserted, Binding)) {
if (Cmp > 0)
S->Binding = Binding;
return Cmp;
}
SymbolBody *B = S->body();
if (isa<DefinedCommon>(B)) {
// Non-common symbols take precedence over common symbols.
if (Config->WarnCommon)
warn("common " + S->body()->getName() + " is overridden");
return 1;
} else if (auto *R = dyn_cast<DefinedRegular>(B)) {
if (R->Section == nullptr && Binding == STB_GLOBAL && IsAbsolute &&
R->Value == Value)
return -1;
}
return 0;
}
template <class ELFT>
Symbol *SymbolTable<ELFT>::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);
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)
warn("common " + S->body()->getName() + " is overridden");
return S;
}
if (Config->WarnCommon)
warn("multiple common of " + S->body()->getName());
Alignment = C->Alignment = std::max(C->Alignment, Alignment);
if (Size > C->Size)
replaceBody<DefinedCommon>(S, N, Size, Alignment, StOther, Type, File);
}
return S;
}
static void warnOrError(const Twine &Msg) {
if (Config->AllowMultipleDefinition)
warn(Msg);
else
error(Msg);
}
static void reportDuplicate(SymbolBody *Sym, InputFile *NewFile) {
warnOrError("duplicate symbol: " + toString(*Sym) +
"\n>>> defined in " + toString(Sym->File) +
"\n>>> defined in " + toString(NewFile));
}
template <class ELFT>
static void reportDuplicate(SymbolBody *Sym, InputSectionBase *ErrSec,
typename ELFT::uint ErrOffset) {
DefinedRegular *D = dyn_cast<DefinedRegular>(Sym);
if (!D || !D->Section || !ErrSec) {
reportDuplicate(Sym, ErrSec ? ErrSec->getFile<ELFT>() : nullptr);
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<ELFT>(D->Value);
std::string Obj1 = Sec1->getObjMsg<ELFT>(D->Value);
std::string Src2 = ErrSec->getSrcMsg<ELFT>(ErrOffset);
std::string Obj2 = ErrSec->getObjMsg<ELFT>(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;
warnOrError(Msg);
}
template <typename ELFT>
Symbol *SymbolTable<ELFT>::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<ELFT>(S, WasInserted, Binding,
Section == nullptr, Value);
if (Cmp > 0)
replaceBody<DefinedRegular>(S, Name, /*IsLocal=*/false, StOther, Type,
Value, Size, Section, File);
else if (Cmp == 0)
reportDuplicate<ELFT>(S->body(),
dyn_cast_or_null<InputSectionBase>(Section), Value);
return S;
}
template <typename ELFT>
void SymbolTable<ELFT>::addShared(SharedFile<ELFT> *File, 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, File);
// Make sure we preempt DSO symbols with default visibility.
if (Sym.getVisibility() == STV_DEFAULT)
S->ExportDynamic = true;
SymbolBody *Body = S->body();
// An undefined symbol with non default visibility must be satisfied
// in the same DSO.
if (WasInserted ||
(isa<Undefined>(Body) && Body->getVisibility() == STV_DEFAULT)) {
replaceBody<SharedSymbol>(S, File, Name, Sym.st_other, Sym.getType(), &Sym,
Verdef);
if (!S->isWeak())
File->IsUsed = true;
}
}
template <class ELFT>
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>(S, Name, /*IsLocal=*/false, StOther, Type, 0, 0,
nullptr, F);
else if (Cmp == 0)
reportDuplicate(S->body(), F);
return S;
}
template <class ELFT> SymbolBody *SymbolTable<ELFT>::find(StringRef Name) {
auto It = Symtab.find(CachedHashStringRef(Name));
if (It == Symtab.end())
return nullptr;
SymIndex V = It->second;
if (V.Idx == -1)
return nullptr;
return SymVector[V.Idx]->body();
}
template <class ELFT>
SymbolBody *SymbolTable<ELFT>::findInCurrentDSO(StringRef Name) {
if (SymbolBody *S = find(Name))
if (S->isInCurrentDSO())
return S;
return nullptr;
}
template <class ELFT>
Symbol *SymbolTable<ELFT>::addLazyArchive(ArchiveFile *F,
const object::Archive::Symbol Sym) {
Symbol *S;
bool WasInserted;
StringRef Name = Sym.getName();
std::tie(S, WasInserted) = insert(Name);
if (WasInserted) {
replaceBody<LazyArchive>(S, *F, Sym, SymbolBody::UnknownType);
return S;
}
if (!S->body()->isUndefined())
return S;
// 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 S;
}
std::pair<MemoryBufferRef, uint64_t> MBInfo = F->getMember(&Sym);
if (!MBInfo.first.getBuffer().empty())
addFile(createObjectFile(MBInfo.first, F->getName(), MBInfo.second));
return S;
}
template <class ELFT>
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 if (InputFile *F = Obj.fetch())
addFile(F);
}
// Process undefined (-u) flags by loading lazy symbols named by those flags.
template <class ELFT> void SymbolTable<ELFT>::scanUndefinedFlags() {
for (StringRef S : Config->Undefined)
if (auto *L = dyn_cast_or_null<Lazy>(find(S)))
if (InputFile *File = L->fetch())
addFile(File);
}
// This function takes care of the case in which shared libraries depend on
// the user program (not the other way, which is usual). Shared libraries
// may have undefined symbols, expecting that the user program provides
// the definitions for them. An example is BSD's __progname symbol.
// We need to put such symbols to the main program's .dynsym so that
// shared libraries can find them.
// Except this, we ignore undefined symbols in DSOs.
template <class ELFT> void SymbolTable<ELFT>::scanShlibUndefined() {
for (SharedFile<ELFT> *File : SharedFiles) {
for (StringRef U : File->getUndefinedSymbols()) {
SymbolBody *Sym = find(U);
if (!Sym || !Sym->isDefined())
continue;
Sym->symbol()->ExportDynamic = true;
// If -dynamic-list is given, the default version is set to
// VER_NDX_LOCAL, which prevents a symbol to be exported via .dynsym.
// Set to VER_NDX_GLOBAL so the symbol will be handled as if it were
// specified by -dynamic-list.
Sym->symbol()->VersionId = VER_NDX_GLOBAL;
}
}
}
// 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.
template <class ELFT>
StringMap<std::vector<SymbolBody *>> &SymbolTable<ELFT>::getDemangledSyms() {
if (!DemangledSyms) {
DemangledSyms.emplace();
for (Symbol *Sym : SymVector) {
SymbolBody *B = Sym->body();
if (B->isUndefined())
continue;
if (Optional<std::string> S = demangle(B->getName()))
(*DemangledSyms)[*S].push_back(B);
else
(*DemangledSyms)[B->getName()].push_back(B);
}
}
return *DemangledSyms;
}
template <class ELFT>
std::vector<SymbolBody *> SymbolTable<ELFT>::findByVersion(SymbolVersion Ver) {
if (Ver.IsExternCpp)
return getDemangledSyms().lookup(Ver.Name);
if (SymbolBody *B = find(Ver.Name))
if (!B->isUndefined())
return {B};
return {};
}
template <class ELFT>
std::vector<SymbolBody *>
SymbolTable<ELFT>::findAllByVersion(SymbolVersion Ver) {
std::vector<SymbolBody *> 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) {
SymbolBody *B = Sym->body();
if (!B->isUndefined() && M.match(B->getName()))
Res.push_back(B);
}
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.
template <class ELFT> void SymbolTable<ELFT>::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);
}
// Set symbol versions to symbols. This function handles patterns
// containing no wildcard characters.
template <class ELFT>
void SymbolTable<ELFT>::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<SymbolBody *> Syms = findByVersion(Ver);
if (Syms.empty()) {
if (Config->NoUndefinedVersion)
error("version script assignment of '" + VersionName + "' to symbol '" +
Ver.Name + "' failed: symbol not defined");
return;
}
// Assign the version.
for (SymbolBody *B : Syms) {
// Skip symbols containing version info because symbol versions
// specified by symbol names take precedence over version scripts.
// See parseSymbolVersion().
if (B->getName().find('@') != StringRef::npos)
continue;
Symbol *Sym = B->symbol();
if (Sym->InVersionScript)
warn("duplicate symbol '" + Ver.Name + "' in version script");
Sym->VersionId = VersionId;
Sym->InVersionScript = true;
}
}
template <class ELFT>
void SymbolTable<ELFT>::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 (SymbolBody *B : findAllByVersion(Ver))
if (B->symbol()->VersionId == Config->DefaultSymbolVersion)
B->symbol()->VersionId = VersionId;
}
// This function processes version scripts by updating VersionId
// member of symbols.
template <class ELFT> void SymbolTable<ELFT>::scanVersionScript() {
// Handle edge cases first.
handleAnonymousVersion();
// 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->body()->parseSymbolVersion();
}
template class elf::SymbolTable<ELF32LE>;
template class elf::SymbolTable<ELF32BE>;
template class elf::SymbolTable<ELF64LE>;
template class elf::SymbolTable<ELF64BE>;
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