forked from OSchip/llvm-project
113 lines
3.9 KiB
C++
113 lines
3.9 KiB
C++
//===- SymbolTable.h --------------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLD_ELF_SYMBOL_TABLE_H
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#define LLD_ELF_SYMBOL_TABLE_H
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#include "InputFiles.h"
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#include "LTO.h"
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#include "lld/Common/Strings.h"
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#include "llvm/ADT/CachedHashString.h"
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#include "llvm/ADT/DenseMap.h"
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namespace lld {
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namespace elf {
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class CommonSymbol;
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class Defined;
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class LazyArchive;
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class LazyObject;
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class SectionBase;
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class SharedSymbol;
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class Undefined;
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// SymbolTable is a bucket of all known symbols, including defined,
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// undefined, or lazy symbols (the last one is symbols in archive
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// files whose archive members are not yet loaded).
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//
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// We put all symbols of all files to a SymbolTable, and the
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// SymbolTable selects the "best" symbols if there are name
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// conflicts. For example, obviously, a defined symbol is better than
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// an undefined symbol. Or, if there's a conflict between a lazy and a
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// undefined, it'll read an archive member to read a real definition
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// to replace the lazy symbol. The logic is implemented in the
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// add*() functions, which are called by input files as they are parsed. There
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// is one add* function per symbol type.
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class SymbolTable {
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public:
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template <class ELFT> void addCombinedLTOObject();
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void wrap(Symbol *Sym, Symbol *Real, Symbol *Wrap);
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ArrayRef<Symbol *> getSymbols() const { return SymVector; }
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Symbol *addUndefined(const Undefined &New);
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Symbol *addDefined(const Defined &New);
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Symbol *addShared(const SharedSymbol &New);
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Symbol *addLazyArchive(const LazyArchive &New);
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Symbol *addLazyObject(const LazyObject &New);
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Symbol *addCommon(const CommonSymbol &New);
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Symbol *insert(const Symbol &New);
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void mergeProperties(Symbol *Old, const Symbol &New);
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void fetchLazy(Symbol *Sym);
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void scanVersionScript();
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Symbol *find(StringRef Name);
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void trace(StringRef Name);
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void handleDynamicList();
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// Set of .so files to not link the same shared object file more than once.
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llvm::DenseMap<StringRef, SharedFile *> SoNames;
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private:
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template <class LazyT> Symbol *addLazy(const LazyT &New);
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std::vector<Symbol *> findByVersion(SymbolVersion Ver);
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std::vector<Symbol *> findAllByVersion(SymbolVersion Ver);
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llvm::StringMap<std::vector<Symbol *>> &getDemangledSyms();
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void handleAnonymousVersion();
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void assignExactVersion(SymbolVersion Ver, uint16_t VersionId,
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StringRef VersionName);
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void assignWildcardVersion(SymbolVersion Ver, uint16_t VersionId);
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// The order the global symbols are in is not defined. We can use an arbitrary
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// order, but it has to be reproducible. That is true even when cross linking.
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// The default hashing of StringRef produces different results on 32 and 64
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// bit systems so we use a map to a vector. That is arbitrary, deterministic
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// but a bit inefficient.
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// FIXME: Experiment with passing in a custom hashing or sorting the symbols
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// once symbol resolution is finished.
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llvm::DenseMap<llvm::CachedHashStringRef, int> SymMap;
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std::vector<Symbol *> SymVector;
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// Comdat groups define "link once" sections. If two comdat groups have the
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// same name, only one of them is linked, and the other is ignored. This set
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// is used to uniquify them.
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llvm::DenseSet<llvm::CachedHashStringRef> ComdatGroups;
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// A map from demangled symbol names to their symbol objects.
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// This mapping is 1:N because two symbols with different versions
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// can have the same name. We use this map to handle "extern C++ {}"
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// directive in version scripts.
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llvm::Optional<llvm::StringMap<std::vector<Symbol *>>> DemangledSyms;
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// For LTO.
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std::unique_ptr<BitcodeCompiler> LTO;
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};
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extern SymbolTable *Symtab;
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} // namespace elf
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} // namespace lld
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#endif
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