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//===- SymbolTable.cpp ----------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "Config.h"
#include "Driver.h"
#include "SymbolTable.h"
#include "lld/Core/Error.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
namespace lld {
namespace coff {
SymbolTable::SymbolTable() {
addSymbol(new DefinedAbsolute("__ImageBase", Config->ImageBase));
if (!Config->EntryName.empty())
addSymbol(new Undefined(Config->EntryName));
}
std::error_code SymbolTable::addFile(std::unique_ptr<InputFile> File) {
if (auto EC = File->parse())
return EC;
InputFile *FileP = File.release();
if (auto *P = dyn_cast<ObjectFile>(FileP))
return addObject(P);
if (auto *P = dyn_cast<ArchiveFile>(FileP))
return addArchive(P);
return addImport(cast<ImportFile>(FileP));
}
std::error_code SymbolTable::addObject(ObjectFile *File) {
ObjectFiles.emplace_back(File);
for (SymbolBody *Body : File->getSymbols())
if (Body->isExternal())
if (auto EC = resolve(Body))
return EC;
// If an object file contains .drectve section, read it and add
// files listed in the section.
StringRef Dir = File->getDirectives();
if (!Dir.empty()) {
std::vector<std::unique_ptr<InputFile>> Libs;
if (auto EC = parseDirectives(Dir, &Libs, &StringAlloc))
return EC;
for (std::unique_ptr<InputFile> &Lib : Libs)
addFile(std::move(Lib));
}
return std::error_code();
}
std::error_code SymbolTable::addArchive(ArchiveFile *File) {
ArchiveFiles.emplace_back(File);
for (SymbolBody *Body : File->getSymbols())
if (auto EC = resolve(Body))
return EC;
return std::error_code();
}
std::error_code SymbolTable::addImport(ImportFile *File) {
ImportFiles.emplace_back(File);
for (SymbolBody *Body : File->getSymbols())
if (auto EC = resolve(Body))
return EC;
return std::error_code();
}
bool SymbolTable::reportRemainingUndefines() {
bool Ret = false;
for (auto &I : Symtab) {
Symbol *Sym = I.second;
auto *Undef = dyn_cast<Undefined>(Sym->Body);
if (!Undef)
continue;
if (SymbolBody *Alias = Undef->getWeakAlias()) {
Sym->Body = Alias->getReplacement();
if (!isa<Defined>(Sym->Body)) {
// Aliases are yet another symbols pointed by other symbols
// that could also remain undefined.
llvm::errs() << "undefined symbol: " << Undef->getName() << "\n";
Ret = true;
}
continue;
}
llvm::errs() << "undefined symbol: " << Undef->getName() << "\n";
Ret = true;
}
return Ret;
}
// This function resolves conflicts if there's an existing symbol with
// the same name. Decisions are made based on symbol type.
std::error_code SymbolTable::resolve(SymbolBody *New) {
// Find an existing Symbol or create and insert a new one.
StringRef Name = New->getName();
Symbol *&Sym = Symtab[Name];
if (!Sym) {
Sym = new (Alloc) Symbol(New);
New->setBackref(Sym);
return std::error_code();
}
New->setBackref(Sym);
// compare() returns -1, 0, or 1 if the lhs symbol is less preferable,
// equivalent (conflicting), or more preferable, respectively.
SymbolBody *Existing = Sym->Body;
int comp = Existing->compare(New);
if (comp < 0)
Sym->Body = New;
if (comp == 0)
return make_dynamic_error_code(Twine("duplicate symbol: ") + Name);
// If we have an Undefined symbol for a Lazy symbol, we need
// to read an archive member to replace the Lazy symbol with
// a Defined symbol.
if (isa<Undefined>(Existing) || isa<Undefined>(New))
if (auto *B = dyn_cast<Lazy>(Sym->Body))
return addMemberFile(B);
return std::error_code();
}
// Reads an archive member file pointed by a given symbol.
std::error_code SymbolTable::addMemberFile(Lazy *Body) {
auto FileOrErr = Body->getMember();
if (auto EC = FileOrErr.getError())
return EC;
std::unique_ptr<InputFile> File = std::move(FileOrErr.get());
// getMember returns an empty buffer if the member was already
// read from the library.
if (!File)
return std::error_code();
if (Config->Verbose)
llvm::dbgs() << "Loaded " << File->getShortName() << " for "
<< Body->getName() << "\n";
return addFile(std::move(File));
}
std::vector<Chunk *> SymbolTable::getChunks() {
std::vector<Chunk *> Res;
for (std::unique_ptr<ObjectFile> &File : ObjectFiles) {
std::vector<Chunk *> &V = File->getChunks();
Res.insert(Res.end(), V.begin(), V.end());
}
return Res;
}
Defined *SymbolTable::find(StringRef Name) {
auto It = Symtab.find(Name);
if (It == Symtab.end())
return nullptr;
if (auto *Def = dyn_cast<Defined>(It->second->Body))
return Def;
return nullptr;
}
// Link default entry point name.
ErrorOr<StringRef> SymbolTable::findDefaultEntry() {
static const char *Entries[][2] = {
{"mainCRTStartup", "mainCRTStartup"},
{"wmainCRTStartup", "wmainCRTStartup"},
{"WinMainCRTStartup", "WinMainCRTStartup"},
{"wWinMainCRTStartup", "wWinMainCRTStartup"},
{"main", "mainCRTStartup"},
{"wmain", "wmainCRTStartup"},
{"WinMain", "WinMainCRTStartup"},
{"wWinMain", "wWinMainCRTStartup"},
};
for (size_t I = 0; I < sizeof(Entries); ++I) {
if (!find(Entries[I][0]))
continue;
if (auto EC = addSymbol(new Undefined(Entries[I][1])))
return EC;
return StringRef(Entries[I][1]);
}
return make_dynamic_error_code("entry point must be defined");
}
std::error_code SymbolTable::addSymbol(SymbolBody *Body) {
OwningSymbols.push_back(std::unique_ptr<SymbolBody>(Body));
return resolve(Body);
}
void SymbolTable::dump() {
for (auto &P : Symtab) {
Symbol *Ref = P.second;
if (auto *Body = dyn_cast<Defined>(Ref->Body))
llvm::dbgs() << Twine::utohexstr(Config->ImageBase + Body->getRVA())
<< " " << Body->getName() << "\n";
}
}
} // namespace coff
} // namespace lld
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