wasm/SymbolTable.h

//===- 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_WASM_SYMBOL_TABLE_H
#define LLD_WASM_SYMBOL_TABLE_H

#include "InputFiles.h"
#include "Symbols.h"

#include "llvm/ADT/CachedHashString.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/raw_ostream.h"

using llvm::object::WasmSymbol;
using llvm::wasm::WasmSignature;

namespace lld {
namespace wasm {

class InputSegment;

// 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:
  void addFile(InputFile *File);

  std::vector<ObjFile *> ObjectFiles;

  void reportDuplicate(Symbol *Existing, InputFile *NewFile);
  void reportRemainingUndefines();

  ArrayRef<Symbol *> getSymbols() const { return SymVector; }
  Symbol *find(StringRef Name);

  Symbol *addDefined(InputFile *F, const WasmSymbol *Sym,
                     const InputSegment *Segment = nullptr);
  Symbol *addUndefined(InputFile *F, const WasmSymbol *Sym);
  Symbol *addUndefinedFunction(StringRef Name, const WasmSignature *Type);
  Symbol *addDefinedGlobal(StringRef Name);
  void addLazy(ArchiveFile *F, const Archive::Symbol *Sym);

private:
  std::pair<Symbol *, bool> insert(StringRef Name);

  llvm::DenseMap<llvm::CachedHashStringRef, Symbol *> SymMap;
  std::vector<Symbol *> SymVector;
};

extern SymbolTable *Symtab;

} // namespace wasm
} // namespace lld

#endif