llvm/lld/ELF/SymbolTable.cpp

//===- SymbolTable.cpp ----------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// 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 "InputFiles.h"
#include "Symbols.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/Memory.h"
#include "lld/Common/Strings.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Demangle/Demangle.h"

usingnamespacellvm;
usingnamespacellvm::object;
usingnamespacellvm::ELF;
usingnamespacelld;
usingnamespacelld::elf;

void SymbolTable::wrap(Symbol *sym, Symbol *real, Symbol *wrap) { … }

// Find an existing symbol or create a new one.
Symbol *SymbolTable::insert(StringRef name) { … }

// This variant of addSymbol is used by BinaryFile::parse to check duplicate
// symbol errors.
Symbol *SymbolTable::addAndCheckDuplicate(const Defined &newSym) { … }

Symbol *SymbolTable::find(StringRef name) { … }

// A version script/dynamic list is only meaningful for a Defined symbol.
// A CommonSymbol will be converted to a Defined in replaceCommonSymbols().
// A lazy symbol may be made Defined if an LTO libcall extracts it.
static bool canBeVersioned(const Symbol &sym) { … }

// 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<SmallVector<Symbol *, 0>> &SymbolTable::getDemangledSyms() { … }

SmallVector<Symbol *, 0> SymbolTable::findByVersion(SymbolVersion ver) { … }

SmallVector<Symbol *, 0> SymbolTable::findAllByVersion(SymbolVersion ver,
                                                       bool includeNonDefault) { … }

void SymbolTable::handleDynamicList() { … }

// Set symbol versions to symbols. This function handles patterns containing no
// wildcard characters. Return false if no symbol definition matches ver.
bool SymbolTable::assignExactVersion(SymbolVersion ver, uint16_t versionId,
                                     StringRef versionName,
                                     bool includeNonDefault) { … }

void SymbolTable::assignWildcardVersion(SymbolVersion ver, uint16_t versionId,
                                        bool includeNonDefault) { … }

// This function processes version scripts by updating the versionId
// member of symbols.
// 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::scanVersionScript() { … }

Symbol *SymbolTable::addUnusedUndefined(StringRef name, uint8_t binding) { … }