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//===- SymbolTable.h --------------------------------------------*- C++ -*-===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLD_ELF_SYMBOL_TABLE_H
#define LLD_ELF_SYMBOL_TABLE_H
#include "InputFiles.h"
#include "LTO.h"
#include "Strings.h"
#include "llvm/ADT/CachedHashString.h"
#include "llvm/ADT/DenseMap.h"
namespace lld {
namespace elf {
class Defined;
class SectionBase;
// SymbolTable is a bucket of all known symbols, including defined,
// undefined, or lazy symbols (the last one is symbols in archive
// files whose archive members are not yet loaded).
//
// We put all symbols of all files to a SymbolTable, and the
// SymbolTable selects the "best" symbols if there are name
// conflicts. For example, obviously, a defined symbol is better than
// an undefined symbol. Or, if there's a conflict between a lazy and a
// undefined, it'll read an archive member to read a real definition
// to replace the lazy symbol. The logic is implemented in the
// add*() functions, which are called by input files as they are parsed. There
// is one add* function per symbol type.
class SymbolTable {
public:
template <class ELFT> void addFile(InputFile *File);
template <class ELFT> void addCombinedLTOObject();
template <class ELFT> void addSymbolWrap(StringRef Name);
void applySymbolWrap();
ArrayRef<Symbol *> getSymbols() const { return SymVector; }
Defined *addAbsolute(StringRef Name,
uint8_t Visibility = llvm::ELF::STV_HIDDEN,
uint8_t Binding = llvm::ELF::STB_GLOBAL);
template <class ELFT> Symbol *addUndefined(StringRef Name);
template <class ELFT>
Symbol *addUndefined(StringRef Name, uint8_t Binding, uint8_t StOther,
uint8_t Type, bool CanOmitFromDynSym, InputFile *File);
Symbol *addRegular(StringRef Name, uint8_t StOther, uint8_t Type,
uint64_t Value, uint64_t Size, uint8_t Binding,
SectionBase *Section, InputFile *File);
template <class ELFT>
void addShared(StringRef Name, SharedFile<ELFT> &F,
const typename ELFT::Sym &Sym, uint32_t Alignment,
uint32_t VerdefIndex);
template <class ELFT>
Symbol *addLazyArchive(StringRef Name, ArchiveFile &F,
const llvm::object::Archive::Symbol S);
template <class ELFT> void addLazyObject(StringRef Name, LazyObjFile &Obj);
Symbol *addBitcode(StringRef Name, uint8_t Binding, uint8_t StOther,
uint8_t Type, bool CanOmitFromDynSym, BitcodeFile &File);
Symbol *addCommon(StringRef Name, uint64_t Size, uint32_t Alignment,
uint8_t Binding, uint8_t StOther, uint8_t Type,
InputFile &File);
std::pair<Symbol *, bool> insert(StringRef Name);
std::pair<Symbol *, bool> insert(StringRef Name, uint8_t Type,
uint8_t Visibility, bool CanOmitFromDynSym,
InputFile *File);
template <class ELFT> void fetchIfLazy(StringRef Name);
template <class ELFT> void scanShlibUndefined();
void scanVersionScript();
Symbol *find(StringRef Name);
void trace(StringRef Name);
void handleDynamicList();
private:
std::vector<Symbol *> findByVersion(SymbolVersion Ver);
std::vector<Symbol *> findAllByVersion(SymbolVersion Ver);
void defsym(Symbol *Dst, Symbol *Src);
llvm::StringMap<std::vector<Symbol *>> &getDemangledSyms();
void handleAnonymousVersion();
void assignExactVersion(SymbolVersion Ver, uint16_t VersionId,
StringRef VersionName);
void assignWildcardVersion(SymbolVersion Ver, uint16_t VersionId);
// The order the global symbols are in is not defined. We can use an arbitrary
// order, but it has to be reproducible. That is true even when cross linking.
// The default hashing of StringRef produces different results on 32 and 64
// bit systems so we use a map to a vector. That is arbitrary, deterministic
// but a bit inefficient.
// FIXME: Experiment with passing in a custom hashing or sorting the symbols
// once symbol resolution is finished.
llvm::DenseMap<llvm::CachedHashStringRef, int> SymMap;
std::vector<Symbol *> SymVector;
// Comdat groups define "link once" sections. If two comdat groups have the
// same name, only one of them is linked, and the other is ignored. This set
// is used to uniquify them.
llvm::DenseSet<llvm::CachedHashStringRef> ComdatGroups;
// Set of .so files to not link the same shared object file more than once.
llvm::DenseSet<StringRef> SoNames;
// A map from demangled symbol names to their symbol objects.
// This mapping is 1:N because two symbols with different versions
// can have the same name. We use this map to handle "extern C++ {}"
// directive in version scripts.
llvm::Optional<llvm::StringMap<std::vector<Symbol *>>> DemangledSyms;
struct WrappedSymbol {
Symbol *Sym;
Symbol *Real;
Symbol *Wrap;
};
// For -wrap.
std::vector<WrappedSymbol> WrappedSymbols;
// For LTO.
std::unique_ptr<BitcodeCompiler> LTO;
};
extern SymbolTable *Symtab;
} // namespace elf
} // namespace lld
#endif
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