forked from OSchip/llvm-project
104 lines
3.6 KiB
C++
104 lines
3.6 KiB
C++
//===- SymbolTable.h ------------------------------------------------------===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLD_COFF_SYMBOL_TABLE_H
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#define LLD_COFF_SYMBOL_TABLE_H
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#include "InputFiles.h"
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#include "llvm/Support/Allocator.h"
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#include <unordered_map>
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namespace llvm {
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struct LTOCodeGenerator;
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}
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namespace lld {
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namespace coff {
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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 resolve().
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class SymbolTable {
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public:
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SymbolTable();
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std::error_code addFile(std::unique_ptr<InputFile> File);
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size_t getVersion() { return Version; }
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// Print an error message on undefined symbols.
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bool reportRemainingUndefines();
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// Returns a list of chunks of selected symbols.
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std::vector<Chunk *> getChunks();
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// Returns a symbol for a given name. It's not guaranteed that the
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// returned symbol actually has the same name (because of various
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// mechanisms to allow aliases, a name can be resolved to a
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// different symbol). Returns a nullptr if not found.
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Defined *find(StringRef Name);
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// Windows specific -- `main` is not the only main function in Windows.
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// You can choose one from these four -- {w,}{WinMain,main}.
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// There are four different entry point functions for them,
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// {w,}{WinMain,main}CRTStartup, respectively. The linker needs to
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// choose the right one depending on which `main` function is defined.
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// This function looks up the symbol table and resolve corresponding
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// entry point name.
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ErrorOr<StringRef> findDefaultEntry();
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// Dump contents of the symbol table to stderr.
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void dump();
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// Build a COFF object representing the combined contents of BitcodeFiles
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// and add it to the symbol table. Called after all files are added and
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// before the writer writes results to a file.
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std::error_code addCombinedLTOObject();
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// The writer needs to handle DLL import libraries specially in
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// order to create the import descriptor table.
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std::vector<std::unique_ptr<ImportFile>> ImportFiles;
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// The writer needs to infer the machine type from the object files.
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std::vector<std::unique_ptr<ObjectFile>> ObjectFiles;
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// Creates an Undefined symbol for a given name.
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std::error_code addUndefined(StringRef Name);
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// Rename From -> To in the symbol table.
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std::error_code rename(StringRef From, StringRef To);
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private:
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std::error_code addDirectives(InputFile *File);
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std::error_code resolve(SymbolBody *Body);
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std::error_code resolveLazy(StringRef Name);
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std::error_code addMemberFile(Lazy *Body);
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ErrorOr<ObjectFile *> createLTOObject(llvm::LTOCodeGenerator *CG);
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std::unordered_map<StringRef, Symbol *> Symtab;
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std::vector<std::unique_ptr<ArchiveFile>> ArchiveFiles;
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std::vector<std::unique_ptr<BitcodeFile>> BitcodeFiles;
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std::unique_ptr<MemoryBuffer> LTOMB;
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llvm::BumpPtrAllocator Alloc;
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// This variable is incremented every time Symtab is updated.
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size_t Version = 0;
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};
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} // namespace coff
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} // namespace lld
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#endif
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