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Driver.cpp
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Driver.cpp
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//===- Driver.cpp ---------------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "Driver.h"
#include "Config.h"
#include "ICF.h"
#include "InputFiles.h"
#include "MarkLive.h"
#include "MinGW.h"
#include "SymbolTable.h"
#include "Symbols.h"
#include "Writer.h"
#include "lld/Common/Args.h"
#include "lld/Common/Driver.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/Memory.h"
#include "lld/Common/Timer.h"
#include "lld/Common/Version.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/BinaryFormat/Magic.h"
#include "llvm/Object/ArchiveWriter.h"
#include "llvm/Object/COFFImportFile.h"
#include "llvm/Object/COFFModuleDefinition.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/ArgList.h"
#include "llvm/Option/Option.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Process.h"
#include "llvm/Support/TarWriter.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ToolDrivers/llvm-lib/LibDriver.h"
#include <algorithm>
#include <future>
#include <memory>
using namespace llvm;
using namespace llvm::object;
using namespace llvm::COFF;
using llvm::sys::Process;
namespace lld {
namespace coff {
static Timer InputFileTimer("Input File Reading", Timer::root());
Configuration *Config;
LinkerDriver *Driver;
bool link(ArrayRef<const char *> Args, bool CanExitEarly, raw_ostream &Diag) {
errorHandler().LogName = args::getFilenameWithoutExe(Args[0]);
errorHandler().ErrorOS = &Diag;
errorHandler().ColorDiagnostics = Diag.has_colors();
errorHandler().ErrorLimitExceededMsg =
"too many errors emitted, stopping now"
" (use /errorlimit:0 to see all errors)";
errorHandler().ExitEarly = CanExitEarly;
Config = make<Configuration>();
Symtab = make<SymbolTable>();
Driver = make<LinkerDriver>();
Driver->link(Args);
// Call exit() if we can to avoid calling destructors.
if (CanExitEarly)
exitLld(errorCount() ? 1 : 0);
freeArena();
ObjFile::Instances.clear();
ImportFile::Instances.clear();
BitcodeFile::Instances.clear();
return !errorCount();
}
// Drop directory components and replace extension with ".exe" or ".dll".
static std::string getOutputPath(StringRef Path) {
auto P = Path.find_last_of("\\/");
StringRef S = (P == StringRef::npos) ? Path : Path.substr(P + 1);
const char* E = Config->DLL ? ".dll" : ".exe";
return (S.substr(0, S.rfind('.')) + E).str();
}
// ErrorOr is not default constructible, so it cannot be used as the type
// parameter of a future.
// FIXME: We could open the file in createFutureForFile and avoid needing to
// return an error here, but for the moment that would cost us a file descriptor
// (a limited resource on Windows) for the duration that the future is pending.
typedef std::pair<std::unique_ptr<MemoryBuffer>, std::error_code> MBErrPair;
// Create a std::future that opens and maps a file using the best strategy for
// the host platform.
static std::future<MBErrPair> createFutureForFile(std::string Path) {
#if _WIN32
// On Windows, file I/O is relatively slow so it is best to do this
// asynchronously.
auto Strategy = std::launch::async;
#else
auto Strategy = std::launch::deferred;
#endif
return std::async(Strategy, [=]() {
auto MBOrErr = MemoryBuffer::getFile(Path,
/*FileSize*/ -1,
/*RequiresNullTerminator*/ false);
if (!MBOrErr)
return MBErrPair{nullptr, MBOrErr.getError()};
return MBErrPair{std::move(*MBOrErr), std::error_code()};
});
}
// Symbol names are mangled by prepending "_" on x86.
static StringRef mangle(StringRef Sym) {
assert(Config->Machine != IMAGE_FILE_MACHINE_UNKNOWN);
if (Config->Machine == I386)
return Saver.save("_" + Sym);
return Sym;
}
static bool findUnderscoreMangle(StringRef Sym) {
StringRef Entry = Symtab->findMangle(mangle(Sym));
return !Entry.empty() && !isa<Undefined>(Symtab->find(Entry));
}
MemoryBufferRef LinkerDriver::takeBuffer(std::unique_ptr<MemoryBuffer> MB) {
MemoryBufferRef MBRef = *MB;
make<std::unique_ptr<MemoryBuffer>>(std::move(MB)); // take ownership
if (Driver->Tar)
Driver->Tar->append(relativeToRoot(MBRef.getBufferIdentifier()),
MBRef.getBuffer());
return MBRef;
}
void LinkerDriver::addBuffer(std::unique_ptr<MemoryBuffer> MB,
bool WholeArchive) {
StringRef Filename = MB->getBufferIdentifier();
MemoryBufferRef MBRef = takeBuffer(std::move(MB));
FilePaths.push_back(Filename);
// File type is detected by contents, not by file extension.
switch (identify_magic(MBRef.getBuffer())) {
case file_magic::windows_resource:
Resources.push_back(MBRef);
break;
case file_magic::archive:
if (WholeArchive) {
std::unique_ptr<Archive> File =
CHECK(Archive::create(MBRef), Filename + ": failed to parse archive");
for (MemoryBufferRef M : getArchiveMembers(File.get()))
addArchiveBuffer(M, "<whole-archive>", Filename);
return;
}
Symtab->addFile(make<ArchiveFile>(MBRef));
break;
case file_magic::bitcode:
Symtab->addFile(make<BitcodeFile>(MBRef));
break;
case file_magic::coff_object:
case file_magic::coff_import_library:
Symtab->addFile(make<ObjFile>(MBRef));
break;
case file_magic::coff_cl_gl_object:
error(Filename + ": is not a native COFF file. Recompile without /GL");
break;
case file_magic::pecoff_executable:
if (Filename.endswith_lower(".dll")) {
error(Filename + ": bad file type. Did you specify a DLL instead of an "
"import library?");
break;
}
LLVM_FALLTHROUGH;
default:
error(MBRef.getBufferIdentifier() + ": unknown file type");
break;
}
}
void LinkerDriver::enqueuePath(StringRef Path, bool WholeArchive) {
auto Future =
std::make_shared<std::future<MBErrPair>>(createFutureForFile(Path));
std::string PathStr = Path;
enqueueTask([=]() {
auto MBOrErr = Future->get();
if (MBOrErr.second)
error("could not open " + PathStr + ": " + MBOrErr.second.message());
else
Driver->addBuffer(std::move(MBOrErr.first), WholeArchive);
});
}
void LinkerDriver::addArchiveBuffer(MemoryBufferRef MB, StringRef SymName,
StringRef ParentName) {
file_magic Magic = identify_magic(MB.getBuffer());
if (Magic == file_magic::coff_import_library) {
Symtab->addFile(make<ImportFile>(MB));
return;
}
InputFile *Obj;
if (Magic == file_magic::coff_object) {
Obj = make<ObjFile>(MB);
} else if (Magic == file_magic::bitcode) {
Obj = make<BitcodeFile>(MB);
} else {
error("unknown file type: " + MB.getBufferIdentifier());
return;
}
Obj->ParentName = ParentName;
Symtab->addFile(Obj);
log("Loaded " + toString(Obj) + " for " + SymName);
}
void LinkerDriver::enqueueArchiveMember(const Archive::Child &C,
StringRef SymName,
StringRef ParentName) {
if (!C.getParent()->isThin()) {
MemoryBufferRef MB = CHECK(
C.getMemoryBufferRef(),
"could not get the buffer for the member defining symbol " + SymName);
enqueueTask([=]() { Driver->addArchiveBuffer(MB, SymName, ParentName); });
return;
}
auto Future = std::make_shared<std::future<MBErrPair>>(createFutureForFile(
CHECK(C.getFullName(),
"could not get the filename for the member defining symbol " +
SymName)));
enqueueTask([=]() {
auto MBOrErr = Future->get();
if (MBOrErr.second)
fatal("could not get the buffer for the member defining " + SymName +
": " + MBOrErr.second.message());
Driver->addArchiveBuffer(takeBuffer(std::move(MBOrErr.first)), SymName,
ParentName);
});
}
static bool isDecorated(StringRef Sym) {
return Sym.startswith("@") || Sym.contains("@@") || Sym.startswith("?") ||
(!Config->MinGW && Sym.contains('@'));
}
// Parses .drectve section contents and returns a list of files
// specified by /defaultlib.
void LinkerDriver::parseDirectives(StringRef S) {
ArgParser Parser;
// .drectve is always tokenized using Windows shell rules.
// /EXPORT: option can appear too many times, processing in fastpath.
opt::InputArgList Args;
std::vector<StringRef> Exports;
std::tie(Args, Exports) = Parser.parseDirectives(S);
for (StringRef E : Exports) {
// If a common header file contains dllexported function
// declarations, many object files may end up with having the
// same /EXPORT options. In order to save cost of parsing them,
// we dedup them first.
if (!DirectivesExports.insert(E).second)
continue;
Export Exp = parseExport(E);
if (Config->Machine == I386 && Config->MinGW) {
if (!isDecorated(Exp.Name))
Exp.Name = Saver.save("_" + Exp.Name);
if (!Exp.ExtName.empty() && !isDecorated(Exp.ExtName))
Exp.ExtName = Saver.save("_" + Exp.ExtName);
}
Exp.Directives = true;
Config->Exports.push_back(Exp);
}
for (auto *Arg : Args) {
switch (Arg->getOption().getUnaliasedOption().getID()) {
case OPT_aligncomm:
parseAligncomm(Arg->getValue());
break;
case OPT_alternatename:
parseAlternateName(Arg->getValue());
break;
case OPT_defaultlib:
if (Optional<StringRef> Path = findLib(Arg->getValue()))
enqueuePath(*Path, false);
break;
case OPT_entry:
Config->Entry = addUndefined(mangle(Arg->getValue()));
break;
case OPT_failifmismatch:
checkFailIfMismatch(Arg->getValue());
break;
case OPT_incl:
addUndefined(Arg->getValue());
break;
case OPT_merge:
parseMerge(Arg->getValue());
break;
case OPT_nodefaultlib:
Config->NoDefaultLibs.insert(doFindLib(Arg->getValue()));
break;
case OPT_section:
parseSection(Arg->getValue());
break;
case OPT_subsystem:
parseSubsystem(Arg->getValue(), &Config->Subsystem,
&Config->MajorOSVersion, &Config->MinorOSVersion);
break;
case OPT_editandcontinue:
case OPT_fastfail:
case OPT_guardsym:
case OPT_natvis:
case OPT_throwingnew:
break;
default:
error(Arg->getSpelling() + " is not allowed in .drectve");
}
}
}
// Find file from search paths. You can omit ".obj", this function takes
// care of that. Note that the returned path is not guaranteed to exist.
StringRef LinkerDriver::doFindFile(StringRef Filename) {
bool HasPathSep = (Filename.find_first_of("/\\") != StringRef::npos);
if (HasPathSep)
return Filename;
bool HasExt = Filename.contains('.');
for (StringRef Dir : SearchPaths) {
SmallString<128> Path = Dir;
sys::path::append(Path, Filename);
if (sys::fs::exists(Path.str()))
return Saver.save(Path.str());
if (!HasExt) {
Path.append(".obj");
if (sys::fs::exists(Path.str()))
return Saver.save(Path.str());
}
}
return Filename;
}
static Optional<sys::fs::UniqueID> getUniqueID(StringRef Path) {
sys::fs::UniqueID Ret;
if (sys::fs::getUniqueID(Path, Ret))
return None;
return Ret;
}
// Resolves a file path. This never returns the same path
// (in that case, it returns None).
Optional<StringRef> LinkerDriver::findFile(StringRef Filename) {
StringRef Path = doFindFile(Filename);
if (Optional<sys::fs::UniqueID> ID = getUniqueID(Path)) {
bool Seen = !VisitedFiles.insert(*ID).second;
if (Seen)
return None;
}
if (Path.endswith_lower(".lib"))
VisitedLibs.insert(sys::path::filename(Path));
return Path;
}
// MinGW specific. If an embedded directive specified to link to
// foo.lib, but it isn't found, try libfoo.a instead.
StringRef LinkerDriver::doFindLibMinGW(StringRef Filename) {
if (Filename.contains('/') || Filename.contains('\\'))
return Filename;
SmallString<128> S = Filename;
sys::path::replace_extension(S, ".a");
StringRef LibName = Saver.save("lib" + S.str());
return doFindFile(LibName);
}
// Find library file from search path.
StringRef LinkerDriver::doFindLib(StringRef Filename) {
// Add ".lib" to Filename if that has no file extension.
bool HasExt = Filename.contains('.');
if (!HasExt)
Filename = Saver.save(Filename + ".lib");
StringRef Ret = doFindFile(Filename);
// For MinGW, if the find above didn't turn up anything, try
// looking for a MinGW formatted library name.
if (Config->MinGW && Ret == Filename)
return doFindLibMinGW(Filename);
return Ret;
}
// Resolves a library path. /nodefaultlib options are taken into
// consideration. This never returns the same path (in that case,
// it returns None).
Optional<StringRef> LinkerDriver::findLib(StringRef Filename) {
if (Config->NoDefaultLibAll)
return None;
if (!VisitedLibs.insert(Filename.lower()).second)
return None;
StringRef Path = doFindLib(Filename);
if (Config->NoDefaultLibs.count(Path))
return None;
if (Optional<sys::fs::UniqueID> ID = getUniqueID(Path))
if (!VisitedFiles.insert(*ID).second)
return None;
return Path;
}
// Parses LIB environment which contains a list of search paths.
void LinkerDriver::addLibSearchPaths() {
Optional<std::string> EnvOpt = Process::GetEnv("LIB");
if (!EnvOpt.hasValue())
return;
StringRef Env = Saver.save(*EnvOpt);
while (!Env.empty()) {
StringRef Path;
std::tie(Path, Env) = Env.split(';');
SearchPaths.push_back(Path);
}
}
Symbol *LinkerDriver::addUndefined(StringRef Name) {
Symbol *B = Symtab->addUndefined(Name);
if (!B->IsGCRoot) {
B->IsGCRoot = true;
Config->GCRoot.push_back(B);
}
return B;
}
// Windows specific -- find default entry point name.
//
// There are four different entry point functions for Windows executables,
// each of which corresponds to a user-defined "main" function. This function
// infers an entry point from a user-defined "main" function.
StringRef LinkerDriver::findDefaultEntry() {
assert(Config->Subsystem != IMAGE_SUBSYSTEM_UNKNOWN &&
"must handle /subsystem before calling this");
if (Config->MinGW)
return mangle(Config->Subsystem == IMAGE_SUBSYSTEM_WINDOWS_GUI
? "WinMainCRTStartup"
: "mainCRTStartup");
if (Config->Subsystem == IMAGE_SUBSYSTEM_WINDOWS_GUI) {
if (findUnderscoreMangle("wWinMain")) {
if (!findUnderscoreMangle("WinMain"))
return mangle("wWinMainCRTStartup");
warn("found both wWinMain and WinMain; using latter");
}
return mangle("WinMainCRTStartup");
}
if (findUnderscoreMangle("wmain")) {
if (!findUnderscoreMangle("main"))
return mangle("wmainCRTStartup");
warn("found both wmain and main; using latter");
}
return mangle("mainCRTStartup");
}
WindowsSubsystem LinkerDriver::inferSubsystem() {
if (Config->DLL)
return IMAGE_SUBSYSTEM_WINDOWS_GUI;
if (Config->MinGW)
return IMAGE_SUBSYSTEM_WINDOWS_CUI;
// Note that link.exe infers the subsystem from the presence of these
// functions even if /entry: or /nodefaultlib are passed which causes them
// to not be called.
bool HaveMain = findUnderscoreMangle("main");
bool HaveWMain = findUnderscoreMangle("wmain");
bool HaveWinMain = findUnderscoreMangle("WinMain");
bool HaveWWinMain = findUnderscoreMangle("wWinMain");
if (HaveMain || HaveWMain) {
if (HaveWinMain || HaveWWinMain) {
warn(std::string("found ") + (HaveMain ? "main" : "wmain") + " and " +
(HaveWinMain ? "WinMain" : "wWinMain") +
"; defaulting to /subsystem:console");
}
return IMAGE_SUBSYSTEM_WINDOWS_CUI;
}
if (HaveWinMain || HaveWWinMain)
return IMAGE_SUBSYSTEM_WINDOWS_GUI;
return IMAGE_SUBSYSTEM_UNKNOWN;
}
static uint64_t getDefaultImageBase() {
if (Config->is64())
return Config->DLL ? 0x180000000 : 0x140000000;
return Config->DLL ? 0x10000000 : 0x400000;
}
static std::string createResponseFile(const opt::InputArgList &Args,
ArrayRef<StringRef> FilePaths,
ArrayRef<StringRef> SearchPaths) {
SmallString<0> Data;
raw_svector_ostream OS(Data);
for (auto *Arg : Args) {
switch (Arg->getOption().getID()) {
case OPT_linkrepro:
case OPT_INPUT:
case OPT_defaultlib:
case OPT_libpath:
case OPT_manifest:
case OPT_manifest_colon:
case OPT_manifestdependency:
case OPT_manifestfile:
case OPT_manifestinput:
case OPT_manifestuac:
break;
default:
OS << toString(*Arg) << "\n";
}
}
for (StringRef Path : SearchPaths) {
std::string RelPath = relativeToRoot(Path);
OS << "/libpath:" << quote(RelPath) << "\n";
}
for (StringRef Path : FilePaths)
OS << quote(relativeToRoot(Path)) << "\n";
return Data.str();
}
enum class DebugKind { Unknown, None, Full, FastLink, GHash, Dwarf, Symtab };
static DebugKind parseDebugKind(const opt::InputArgList &Args) {
auto *A = Args.getLastArg(OPT_debug, OPT_debug_opt);
if (!A)
return DebugKind::None;
if (A->getNumValues() == 0)
return DebugKind::Full;
DebugKind Debug = StringSwitch<DebugKind>(A->getValue())
.CaseLower("none", DebugKind::None)
.CaseLower("full", DebugKind::Full)
.CaseLower("fastlink", DebugKind::FastLink)
// LLD extensions
.CaseLower("ghash", DebugKind::GHash)
.CaseLower("dwarf", DebugKind::Dwarf)
.CaseLower("symtab", DebugKind::Symtab)
.Default(DebugKind::Unknown);
if (Debug == DebugKind::FastLink) {
warn("/debug:fastlink unsupported; using /debug:full");
return DebugKind::Full;
}
if (Debug == DebugKind::Unknown) {
error("/debug: unknown option: " + Twine(A->getValue()));
return DebugKind::None;
}
return Debug;
}
static unsigned parseDebugTypes(const opt::InputArgList &Args) {
unsigned DebugTypes = static_cast<unsigned>(DebugType::None);
if (auto *A = Args.getLastArg(OPT_debugtype)) {
SmallVector<StringRef, 3> Types;
A->getSpelling().split(Types, ',', /*KeepEmpty=*/false);
for (StringRef Type : Types) {
unsigned V = StringSwitch<unsigned>(Type.lower())
.Case("cv", static_cast<unsigned>(DebugType::CV))
.Case("pdata", static_cast<unsigned>(DebugType::PData))
.Case("fixup", static_cast<unsigned>(DebugType::Fixup))
.Default(0);
if (V == 0) {
warn("/debugtype: unknown option: " + Twine(A->getValue()));
continue;
}
DebugTypes |= V;
}
return DebugTypes;
}
// Default debug types
DebugTypes = static_cast<unsigned>(DebugType::CV);
if (Args.hasArg(OPT_driver))
DebugTypes |= static_cast<unsigned>(DebugType::PData);
if (Args.hasArg(OPT_profile))
DebugTypes |= static_cast<unsigned>(DebugType::Fixup);
return DebugTypes;
}
static std::string getMapFile(const opt::InputArgList &Args) {
auto *Arg = Args.getLastArg(OPT_lldmap, OPT_lldmap_file);
if (!Arg)
return "";
if (Arg->getOption().getID() == OPT_lldmap_file)
return Arg->getValue();
assert(Arg->getOption().getID() == OPT_lldmap);
StringRef OutFile = Config->OutputFile;
return (OutFile.substr(0, OutFile.rfind('.')) + ".map").str();
}
static std::string getImplibPath() {
if (!Config->Implib.empty())
return Config->Implib;
SmallString<128> Out = StringRef(Config->OutputFile);
sys::path::replace_extension(Out, ".lib");
return Out.str();
}
//
// The import name is caculated as the following:
//
// | LIBRARY w/ ext | LIBRARY w/o ext | no LIBRARY
// -----+----------------+---------------------+------------------
// LINK | {value} | {value}.{.dll/.exe} | {output name}
// LIB | {value} | {value}.dll | {output name}.dll
//
static std::string getImportName(bool AsLib) {
SmallString<128> Out;
if (Config->ImportName.empty()) {
Out.assign(sys::path::filename(Config->OutputFile));
if (AsLib)
sys::path::replace_extension(Out, ".dll");
} else {
Out.assign(Config->ImportName);
if (!sys::path::has_extension(Out))
sys::path::replace_extension(Out,
(Config->DLL || AsLib) ? ".dll" : ".exe");
}
return Out.str();
}
static void createImportLibrary(bool AsLib) {
std::vector<COFFShortExport> Exports;
for (Export &E1 : Config->Exports) {
COFFShortExport E2;
E2.Name = E1.Name;
E2.SymbolName = E1.SymbolName;
E2.ExtName = E1.ExtName;
E2.Ordinal = E1.Ordinal;
E2.Noname = E1.Noname;
E2.Data = E1.Data;
E2.Private = E1.Private;
E2.Constant = E1.Constant;
Exports.push_back(E2);
}
auto HandleError = [](Error &&E) {
handleAllErrors(std::move(E),
[](ErrorInfoBase &EIB) { error(EIB.message()); });
};
std::string LibName = getImportName(AsLib);
std::string Path = getImplibPath();
if (!Config->Incremental) {
HandleError(writeImportLibrary(LibName, Path, Exports, Config->Machine,
Config->MinGW));
return;
}
// If the import library already exists, replace it only if the contents
// have changed.
ErrorOr<std::unique_ptr<MemoryBuffer>> OldBuf = MemoryBuffer::getFile(
Path, /*FileSize*/ -1, /*RequiresNullTerminator*/ false);
if (!OldBuf) {
HandleError(writeImportLibrary(LibName, Path, Exports, Config->Machine,
Config->MinGW));
return;
}
SmallString<128> TmpName;
if (std::error_code EC =
sys::fs::createUniqueFile(Path + ".tmp-%%%%%%%%.lib", TmpName))
fatal("cannot create temporary file for import library " + Path + ": " +
EC.message());
if (Error E = writeImportLibrary(LibName, TmpName, Exports, Config->Machine,
Config->MinGW)) {
HandleError(std::move(E));
return;
}
std::unique_ptr<MemoryBuffer> NewBuf = check(MemoryBuffer::getFile(
TmpName, /*FileSize*/ -1, /*RequiresNullTerminator*/ false));
if ((*OldBuf)->getBuffer() != NewBuf->getBuffer()) {
OldBuf->reset();
HandleError(errorCodeToError(sys::fs::rename(TmpName, Path)));
} else {
sys::fs::remove(TmpName);
}
}
static void parseModuleDefs(StringRef Path) {
std::unique_ptr<MemoryBuffer> MB = CHECK(
MemoryBuffer::getFile(Path, -1, false, true), "could not open " + Path);
COFFModuleDefinition M = check(parseCOFFModuleDefinition(
MB->getMemBufferRef(), Config->Machine, Config->MinGW));
if (Config->OutputFile.empty())
Config->OutputFile = Saver.save(M.OutputFile);
Config->ImportName = Saver.save(M.ImportName);
if (M.ImageBase)
Config->ImageBase = M.ImageBase;
if (M.StackReserve)
Config->StackReserve = M.StackReserve;
if (M.StackCommit)
Config->StackCommit = M.StackCommit;
if (M.HeapReserve)
Config->HeapReserve = M.HeapReserve;
if (M.HeapCommit)
Config->HeapCommit = M.HeapCommit;
if (M.MajorImageVersion)
Config->MajorImageVersion = M.MajorImageVersion;
if (M.MinorImageVersion)
Config->MinorImageVersion = M.MinorImageVersion;
if (M.MajorOSVersion)
Config->MajorOSVersion = M.MajorOSVersion;
if (M.MinorOSVersion)
Config->MinorOSVersion = M.MinorOSVersion;
for (COFFShortExport E1 : M.Exports) {
Export E2;
// In simple cases, only Name is set. Renamed exports are parsed
// and set as "ExtName = Name". If Name has the form "OtherDll.Func",
// it shouldn't be a normal exported function but a forward to another
// DLL instead. This is supported by both MS and GNU linkers.
if (E1.ExtName != E1.Name && StringRef(E1.Name).contains('.')) {
E2.Name = Saver.save(E1.ExtName);
E2.ForwardTo = Saver.save(E1.Name);
Config->Exports.push_back(E2);
continue;
}
E2.Name = Saver.save(E1.Name);
E2.ExtName = Saver.save(E1.ExtName);
E2.Ordinal = E1.Ordinal;
E2.Noname = E1.Noname;
E2.Data = E1.Data;
E2.Private = E1.Private;
E2.Constant = E1.Constant;
Config->Exports.push_back(E2);
}
}
void LinkerDriver::enqueueTask(std::function<void()> Task) {
TaskQueue.push_back(std::move(Task));
}
bool LinkerDriver::run() {
ScopedTimer T(InputFileTimer);
bool DidWork = !TaskQueue.empty();
while (!TaskQueue.empty()) {
TaskQueue.front()();
TaskQueue.pop_front();
}
return DidWork;
}
// Parse an /order file. If an option is given, the linker places
// COMDAT sections in the same order as their names appear in the
// given file.
static void parseOrderFile(StringRef Arg) {
// For some reason, the MSVC linker requires a filename to be
// preceded by "@".
if (!Arg.startswith("@")) {
error("malformed /order option: '@' missing");
return;
}
// Get a list of all comdat sections for error checking.
DenseSet<StringRef> Set;
for (Chunk *C : Symtab->getChunks())
if (auto *Sec = dyn_cast<SectionChunk>(C))
if (Sec->Sym)
Set.insert(Sec->Sym->getName());
// Open a file.
StringRef Path = Arg.substr(1);
std::unique_ptr<MemoryBuffer> MB = CHECK(
MemoryBuffer::getFile(Path, -1, false, true), "could not open " + Path);
// Parse a file. An order file contains one symbol per line.
// All symbols that were not present in a given order file are
// considered to have the lowest priority 0 and are placed at
// end of an output section.
for (std::string S : args::getLines(MB->getMemBufferRef())) {
if (Config->Machine == I386 && !isDecorated(S))
S = "_" + S;
if (Set.count(S) == 0) {
if (Config->WarnMissingOrderSymbol)
warn("/order:" + Arg + ": missing symbol: " + S + " [LNK4037]");
}
else
Config->Order[S] = INT_MIN + Config->Order.size();
}
}
static void markAddrsig(Symbol *S) {
if (auto *D = dyn_cast_or_null<Defined>(S))
if (Chunk *C = D->getChunk())
C->KeepUnique = true;
}
static void findKeepUniqueSections() {
// Exported symbols could be address-significant in other executables or DSOs,
// so we conservatively mark them as address-significant.
for (Export &R : Config->Exports)
markAddrsig(R.Sym);
// Visit the address-significance table in each object file and mark each
// referenced symbol as address-significant.
for (ObjFile *Obj : ObjFile::Instances) {
ArrayRef<Symbol *> Syms = Obj->getSymbols();
if (Obj->AddrsigSec) {
ArrayRef<uint8_t> Contents;
Obj->getCOFFObj()->getSectionContents(Obj->AddrsigSec, Contents);
const uint8_t *Cur = Contents.begin();
while (Cur != Contents.end()) {
unsigned Size;
const char *Err;
uint64_t SymIndex = decodeULEB128(Cur, &Size, Contents.end(), &Err);
if (Err)
fatal(toString(Obj) + ": could not decode addrsig section: " + Err);
if (SymIndex >= Syms.size())
fatal(toString(Obj) + ": invalid symbol index in addrsig section");
markAddrsig(Syms[SymIndex]);
Cur += Size;
}
} else {
// If an object file does not have an address-significance table,
// conservatively mark all of its symbols as address-significant.
for (Symbol *S : Syms)
markAddrsig(S);
}
}
}
// link.exe replaces each %foo% in AltPath with the contents of environment
// variable foo, and adds the two magic env vars _PDB (expands to the basename
// of pdb's output path) and _EXT (expands to the extension of the output
// binary).
// lld only supports %_PDB% and %_EXT% and warns on references to all other env
// vars.
static void parsePDBAltPath(StringRef AltPath) {
SmallString<128> Buf;
StringRef PDBBasename =
sys::path::filename(Config->PDBPath, sys::path::Style::windows);
StringRef BinaryExtension =
sys::path::extension(Config->OutputFile, sys::path::Style::windows);
if (!BinaryExtension.empty())
BinaryExtension = BinaryExtension.substr(1); // %_EXT% does not include '.'.
// Invariant:
// +--------- Cursor ('a...' might be the empty string).
// | +----- FirstMark
// | | +- SecondMark
// v v v
// a...%...%...
size_t Cursor = 0;
while (Cursor < AltPath.size()) {
size_t FirstMark, SecondMark;
if ((FirstMark = AltPath.find('%', Cursor)) == StringRef::npos ||
(SecondMark = AltPath.find('%', FirstMark + 1)) == StringRef::npos) {
// Didn't find another full fragment, treat rest of string as literal.
Buf.append(AltPath.substr(Cursor));
break;
}
// Found a full fragment. Append text in front of first %, and interpret
// text between first and second % as variable name.
Buf.append(AltPath.substr(Cursor, FirstMark - Cursor));
StringRef Var = AltPath.substr(FirstMark, SecondMark - FirstMark + 1);
if (Var.equals_lower("%_pdb%"))
Buf.append(PDBBasename);
else if (Var.equals_lower("%_ext%"))
Buf.append(BinaryExtension);
else {
warn("only %_PDB% and %_EXT% supported in /pdbaltpath:, keeping " +
Var + " as literal");
Buf.append(Var);
}
Cursor = SecondMark + 1;
}
Config->PDBAltPath = Buf;
}
void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
// If the first command line argument is "/lib", link.exe acts like lib.exe.
// We call our own implementation of lib.exe that understands bitcode files.
if (ArgsArr.size() > 1 && StringRef(ArgsArr[1]).equals_lower("/lib")) {
if (llvm::libDriverMain(ArgsArr.slice(1)) != 0)
fatal("lib failed");
return;
}
// Needed for LTO.
InitializeAllTargetInfos();
InitializeAllTargets();
InitializeAllTargetMCs();
InitializeAllAsmParsers();
InitializeAllAsmPrinters();
// Parse command line options.
ArgParser Parser;
opt::InputArgList Args = Parser.parseLINK(ArgsArr);
// Parse and evaluate -mllvm options.
std::vector<const char *> V;
V.push_back("lld-link (LLVM option parsing)");
for (auto *Arg : Args.filtered(OPT_mllvm))
V.push_back(Arg->getValue());
cl::ParseCommandLineOptions(V.size(), V.data());
// Handle /errorlimit early, because error() depends on it.
if (auto *Arg = Args.getLastArg(OPT_errorlimit)) {
int N = 20;
StringRef S = Arg->getValue();
if (S.getAsInteger(10, N))
error(Arg->getSpelling() + " number expected, but got " + S);
errorHandler().ErrorLimit = N;
}
// Handle /help
if (Args.hasArg(OPT_help)) {
printHelp(ArgsArr[0]);
return;
}
if (Args.hasArg(OPT_show_timing))
Config->ShowTiming = true;
ScopedTimer T(Timer::root());
// Handle --version, which is an lld extension. This option is a bit odd
// because it doesn't start with "/", but we deliberately chose "--" to
// avoid conflict with /version and for compatibility with clang-cl.
if (Args.hasArg(OPT_dash_dash_version)) {
outs() << getLLDVersion() << "\n";
return;
}
// Handle /lldmingw early, since it can potentially affect how other
// options are handled.
Config->MinGW = Args.hasArg(OPT_lldmingw);
if (auto *Arg = Args.getLastArg(OPT_linkrepro)) {
SmallString<64> Path = StringRef(Arg->getValue());
sys::path::append(Path, "repro.tar");
Expected<std::unique_ptr<TarWriter>> ErrOrWriter =
TarWriter::create(Path, "repro");
if (ErrOrWriter) {
Tar = std::move(*ErrOrWriter);
} else {
error("/linkrepro: failed to open " + Path + ": " +
toString(ErrOrWriter.takeError()));
}
}
if (!Args.hasArg(OPT_INPUT)) {
if (Args.hasArg(OPT_deffile))
Config->NoEntry = true;
else
fatal("no input files");
}
// Construct search path list.
SearchPaths.push_back("");
for (auto *Arg : Args.filtered(OPT_libpath))
SearchPaths.push_back(Arg->getValue());
addLibSearchPaths();
// Handle /ignore
for (auto *Arg : Args.filtered(OPT_ignore)) {
SmallVector<StringRef, 8> Vec;
StringRef(Arg->getValue()).split(Vec, ',');
for (StringRef S : Vec) {
if (S == "4037")
Config->WarnMissingOrderSymbol = false;
else if (S == "4099")
Config->WarnDebugInfoUnusable = false;
else if (S == "4217")
Config->WarnLocallyDefinedImported = false;
// Other warning numbers are ignored.
}
}