SymbolTable.h
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//===- Core/SymbolTable.h - Main Symbol Table -----------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef LLD_CORE_SYMBOL_TABLE_H
#define LLD_CORE_SYMBOL_TABLE_H
#include "lld/Common/LLVM.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/Support/DJB.h"
#include <cstring>
#include <map>
#include <vector>
namespace lld {
class AbsoluteAtom;
class Atom;
class DefinedAtom;
class LinkingContext;
class ResolverOptions;
class SharedLibraryAtom;
class UndefinedAtom;
/// The SymbolTable class is responsible for coalescing atoms.
///
/// All atoms coalescable by-name or by-content should be added.
/// The method replacement() can be used to find the replacement atom
/// if an atom has been coalesced away.
class SymbolTable {
public:
/// add atom to symbol table
bool add(const DefinedAtom &);
/// add atom to symbol table
bool add(const UndefinedAtom &);
/// add atom to symbol table
bool add(const SharedLibraryAtom &);
/// add atom to symbol table
bool add(const AbsoluteAtom &);
/// returns atom in symbol table for specified name (or nullptr)
const Atom *findByName(StringRef sym);
/// returns vector of remaining UndefinedAtoms
std::vector<const UndefinedAtom *> undefines();
/// if atom has been coalesced away, return replacement, else return atom
const Atom *replacement(const Atom *);
/// if atom has been coalesced away, return true
bool isCoalescedAway(const Atom *);
private:
typedef llvm::DenseMap<const Atom *, const Atom *> AtomToAtom;
struct StringRefMappingInfo {
static StringRef getEmptyKey() { return StringRef(); }
static StringRef getTombstoneKey() { return StringRef(" ", 1); }
static unsigned getHashValue(StringRef const val) {
return llvm::djbHash(val, 0);
}
static bool isEqual(StringRef const lhs, StringRef const rhs) {
return lhs.equals(rhs);
}
};
typedef llvm::DenseMap<StringRef, const Atom *,
StringRefMappingInfo> NameToAtom;
struct AtomMappingInfo {
static const DefinedAtom * getEmptyKey() { return nullptr; }
static const DefinedAtom * getTombstoneKey() { return (DefinedAtom*)(-1); }
static unsigned getHashValue(const DefinedAtom * const Val);
static bool isEqual(const DefinedAtom * const LHS,
const DefinedAtom * const RHS);
};
typedef llvm::DenseSet<const DefinedAtom*, AtomMappingInfo> AtomContentSet;
bool addByName(const Atom &);
bool addByContent(const DefinedAtom &);
AtomToAtom _replacedAtoms;
NameToAtom _nameTable;
AtomContentSet _contentTable;
};
} // namespace lld
#endif // LLD_CORE_SYMBOL_TABLE_H