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llvm-project/lld/COFF/Driver.cpp

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//===- Driver.cpp ---------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "Driver.h"
#include "Config.h"
#include "DebugTypes.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/Filesystem.h"
#include "lld/Common/Memory.h"
#include "lld/Common/Threads.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/LTO/LTO.h"
#include "llvm/Object/ArchiveWriter.h"
#include "llvm/Object/COFFImportFile.h"
#include "llvm/Object/COFFModuleDefinition.h"
#include "llvm/Object/WindowsMachineFlag.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/MathExtras.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 namespace llvm::sys;
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().errorLimitExceededMsg =
"too many errors emitted, stopping now"
" (use /errorlimit:0 to see all errors)";
errorHandler().exitEarly = canExitEarly;
enableColors(diag.has_colors());
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();
memset(MergeChunk::instances, 0, sizeof(MergeChunk::instances));
return !errorCount();
}
// Parse options of the form "old;new".
static std::pair<StringRef, StringRef> getOldNewOptions(opt::InputArgList &args,
unsigned id) {
auto *arg = args.getLastArg(id);
if (!arg)
return {"", ""};
StringRef s = arg->getValue();
std::pair<StringRef, StringRef> ret = s.split(';');
if (ret.second.empty())
error(arg->getSpelling() + " expects 'old;new' format, but got " + s);
return ret;
}
// 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();
}
// Returns true if S matches /crtend.?\.o$/.
static bool isCrtend(StringRef s) {
if (!s.endswith(".o"))
return false;
s = s.drop_back(2);
if (s.endswith("crtend"))
return true;
return !s.empty() && s.drop_back().endswith("crtend");
}
// 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.
using MBErrPair = std::pair<std::unique_ptr<MemoryBuffer>, std::error_code>;
// 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) {
Symbol *s = symtab->findMangle(mangle(sym));
return s && !isa<Undefined>(s);
}
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, bool lazy) {
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");
Archive *archive = file.get();
make<std::unique_ptr<Archive>>(std::move(file)); // take ownership
int memberIndex = 0;
for (MemoryBufferRef m : getArchiveMembers(archive))
addArchiveBuffer(m, "<whole-archive>", filename, memberIndex++);
return;
}
symtab->addFile(make<ArchiveFile>(mbref));
break;
case file_magic::bitcode:
if (lazy)
symtab->addFile(make<LazyObjFile>(mbref));
else
symtab->addFile(make<BitcodeFile>(mbref, "", 0));
break;
case file_magic::coff_object:
case file_magic::coff_import_library:
if (lazy)
symtab->addFile(make<LazyObjFile>(mbref));
else
symtab->addFile(make<ObjFile>(mbref));
break;
case file_magic::pdb:
loadTypeServerSource(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, bool lazy) {
auto future =
std::make_shared<std::future<MBErrPair>>(createFutureForFile(path));
std::string pathStr = path;
enqueueTask([=]() {
auto mbOrErr = future->get();
if (mbOrErr.second) {
std::string msg =
"could not open '" + pathStr + "': " + mbOrErr.second.message();
// Check if the filename is a typo for an option flag. OptTable thinks
// that all args that are not known options and that start with / are
// filenames, but e.g. `/nodefaultlibs` is more likely a typo for
// the option `/nodefaultlib` than a reference to a file in the root
// directory.
std::string nearest;
if (COFFOptTable().findNearest(pathStr, nearest) > 1)
error(msg);
else
error(msg + "; did you mean '" + nearest + "'");
} else
driver->addBuffer(std::move(mbOrErr.first), wholeArchive, lazy);
});
}
void LinkerDriver::addArchiveBuffer(MemoryBufferRef mb, StringRef symName,
StringRef parentName,
uint64_t offsetInArchive) {
file_magic magic = identify_magic(mb.getBuffer());
if (magic == file_magic::coff_import_library) {
InputFile *imp = make<ImportFile>(mb);
imp->parentName = parentName;
symtab->addFile(imp);
return;
}
InputFile *obj;
if (magic == file_magic::coff_object) {
obj = make<ObjFile>(mb);
} else if (magic == file_magic::bitcode) {
obj = make<BitcodeFile>(mb, parentName, offsetInArchive);
} 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,
const Archive::Symbol &sym,
StringRef parentName) {
auto reportBufferError = [=](Error &&e, StringRef childName) {
fatal("could not get the buffer for the member defining symbol " +
toCOFFString(sym) + ": " + parentName + "(" + childName + "): " +
toString(std::move(e)));
};
if (!c.getParent()->isThin()) {
uint64_t offsetInArchive = c.getChildOffset();
Expected<MemoryBufferRef> mbOrErr = c.getMemoryBufferRef();
if (!mbOrErr)
reportBufferError(mbOrErr.takeError(), check(c.getFullName()));
MemoryBufferRef mb = mbOrErr.get();
enqueueTask([=]() {
driver->addArchiveBuffer(mb, toCOFFString(sym), parentName,
offsetInArchive);
});
return;
}
std::string childName = CHECK(
c.getFullName(),
"could not get the filename for the member defining symbol " +
toCOFFString(sym));
auto future = std::make_shared<std::future<MBErrPair>>(
createFutureForFile(childName));
enqueueTask([=]() {
auto mbOrErr = future->get();
if (mbOrErr.second)
reportBufferError(errorCodeToError(mbOrErr.second), childName);
// Pass empty string as archive name so that the original filename is
// used as the buffer identifier.
driver->addArchiveBuffer(takeBuffer(std::move(mbOrErr.first)),
toCOFFString(sym), "", /*OffsetInArchive=*/0);
});
}
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(InputFile *file) {
StringRef s = file->getDirectives();
if (s.empty())
return;
log("Directives: " + toString(file) + ": " + 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().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, false);
break;
case OPT_entry:
config->entry = addUndefined(mangle(arg->getValue()));
break;
case OPT_failifmismatch:
checkFailIfMismatch(arg->getValue(), file);
break;
case OPT_incl:
addUndefined(arg->getValue());
break;
case OPT_merge:
parseMerge(arg->getValue());
break;
case OPT_nodefaultlib:
config->noDefaultLibs.insert(doFindLib(arg->getValue()).lower());
break;
case OPT_section:
parseSection(arg->getValue());
break;
case OPT_subsystem:
parseSubsystem(arg->getValue(), &config->subsystem,
&config->majorOSVersion, &config->minorOSVersion);
break;
// Only add flags here that link.exe accepts in
// `#pragma comment(linker, "/flag")`-generated sections.
case OPT_editandcontinue:
case OPT_guardsym:
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.lower()))
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;
}
StringRef LinkerDriver::mangleMaybe(Symbol *s) {
// If the plain symbol name has already been resolved, do nothing.
Undefined *unmangled = dyn_cast<Undefined>(s);
if (!unmangled)
return "";
// Otherwise, see if a similar, mangled symbol exists in the symbol table.
Symbol *mangled = symtab->findMangle(unmangled->getName());
if (!mangled)
return "";
// If we find a similar mangled symbol, make this an alias to it and return
// its name.
log(unmangled->getName() + " aliased to " + mangled->getName());
unmangled->weakAlias = symtab->addUndefined(mangled->getName());
return mangled->getName();
}
// 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;
case OPT_implib:
case OPT_pdb:
case OPT_out:
os << arg->getSpelling() << sys::path::filename(arg->getValue()) << "\n";
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;
StringRef(a->getValue())
.split(types, ',', /*MaxSplit=*/-1, /*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 '" + type + "'");
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.isPrivate;
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.isPrivate = 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 (SectionChunk *c = dyn_cast_or_null<SectionChunk>(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;
cantFail(
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;
}
/// Convert resource files and potentially merge input resource object
/// trees into one resource tree.
/// Call after ObjFile::Instances is complete.
void LinkerDriver::convertResources() {
std::vector<ObjFile *> resourceObjFiles;
for (ObjFile *f : ObjFile::instances) {
if (f->isResourceObjFile())
resourceObjFiles.push_back(f);
}
if (!config->mingw &&
(resourceObjFiles.size() > 1 ||
(resourceObjFiles.size() == 1 && !resources.empty()))) {
error((!resources.empty() ? "internal .obj file created from .res files"
: toString(resourceObjFiles[1])) +
": more than one resource obj file not allowed, already got " +
toString(resourceObjFiles.front()));
return;
}
if (resources.empty() && resourceObjFiles.size() <= 1) {
// No resources to convert, and max one resource object file in
// the input. Keep that preconverted resource section as is.
for (ObjFile *f : resourceObjFiles)
f->includeResourceChunks();
return;
}
ObjFile *f = make<ObjFile>(convertResToCOFF(resources, resourceObjFiles));
symtab->addFile(f);
f->includeResourceChunks();
}
// In MinGW, if no symbols are chosen to be exported, then all symbols are
// automatically exported by default. This behavior can be forced by the
// -export-all-symbols option, so that it happens even when exports are
// explicitly specified. The automatic behavior can be disabled using the
// -exclude-all-symbols option, so that lld-link behaves like link.exe rather
// than MinGW in the case that nothing is explicitly exported.
void LinkerDriver::maybeExportMinGWSymbols(const opt::InputArgList &args) {
if (!config->dll)
return;
if (!args.hasArg(OPT_export_all_symbols)) {
if (!config->exports.empty())
return;
if (args.hasArg(OPT_exclude_all_symbols))
return;
}
AutoExporter exporter;
for (auto *arg : args.filtered(OPT_wholearchive_file))
if (Optional<StringRef> path = doFindFile(arg->getValue()))
exporter.addWholeArchive(*path);
symtab->forEachSymbol([&](Symbol *s) {
auto *def = dyn_cast<Defined>(s);
if (!exporter.shouldExport(def))
return;
Export e;
e.name = def->getName();
e.sym = def;
if (Chunk *c = def->getChunk())
if (!(c->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE))
e.data = true;
config->exports.push_back(e);
});
}
void LinkerDriver::link(ArrayRef<const char *> argsArr) {
// Needed for LTO.
InitializeAllTargetInfos();
InitializeAllTargets();
InitializeAllTargetMCs();
InitializeAllAsmParsers();
InitializeAllAsmPrinters();
// 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;
}
// Parse command line options.
ArgParser parser;
opt::InputArgList args = parser.parse(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;
}
lld::threadsEnabled = args.hasFlag(OPT_threads, OPT_threads_no, true);
if (args.hasArg(OPT_show_timing))
config->showTiming = true;
config->showSummary = args.hasArg(OPT_summary);
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)) {
const char *path = arg->getValue();
Expected<std::unique_ptr<TarWriter>> errOrWriter =
TarWriter::create(path, path::stem(path));
if (errOrWriter) {
tar = std::move(*errOrWriter);
tar->append("version.txt", getLLDVersion() + "\n");
} else {
error("/linkrepro: " + 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());
if (!args.hasArg(OPT_lldignoreenv))
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.
}
}
// Handle /out
if (auto *arg = args.getLastArg(OPT_out))
config->outputFile = arg->getValue();
// Handle /verbose
if (args.hasArg(OPT_verbose))
config->verbose = true;
errorHandler().verbose = config->verbose;
// Handle /force or /force:unresolved
if (args.hasArg(OPT_force, OPT_force_unresolved))
config->forceUnresolved = true;
// Handle /force or /force:multiple
if (args.hasArg(OPT_force, OPT_force_multiple))
config->forceMultiple = true;
// Handle /force or /force:multipleres
if (args.hasArg(OPT_force, OPT_force_multipleres))
config->forceMultipleRes = true;
// Handle /debug
DebugKind debug = parseDebugKind(args);
if (debug == DebugKind::Full || debug == DebugKind::Dwarf ||
debug == DebugKind::GHash) {
config->debug = true;
config->incremental = true;
}
// Handle /demangle
config->demangle = args.hasFlag(OPT_demangle, OPT_demangle_no);
// Handle /debugtype
config->debugTypes = parseDebugTypes(args);
// Handle /pdb
bool shouldCreatePDB =
(debug == DebugKind::Full || debug == DebugKind::GHash);
if (shouldCreatePDB) {
if (auto *arg = args.getLastArg(OPT_pdb))
config->pdbPath = arg->getValue();
if (auto *arg = args.getLastArg(OPT_pdbaltpath))
config->pdbAltPath = arg->getValue();
if (args.hasArg(OPT_natvis))
config->natvisFiles = args.getAllArgValues(OPT_natvis);
if (auto *arg = args.getLastArg(OPT_pdb_source_path))
config->pdbSourcePath = arg->getValue();
}
// Handle /noentry
if (args.hasArg(OPT_noentry)) {
if (args.hasArg(OPT_dll))
config->noEntry = true;
else
error("/noentry must be specified with /dll");
}
// Handle /dll
if (args.hasArg(OPT_dll)) {
config->dll = true;
config->manifestID = 2;
}
// Handle /dynamicbase and /fixed. We can't use hasFlag for /dynamicbase
// because we need to explicitly check whether that option or its inverse was
// present in the argument list in order to handle /fixed.
auto *dynamicBaseArg = args.getLastArg(OPT_dynamicbase, OPT_dynamicbase_no);
if (dynamicBaseArg &&
dynamicBaseArg->getOption().getID() == OPT_dynamicbase_no)
config->dynamicBase = false;
// MSDN claims "/FIXED:NO is the default setting for a DLL, and /FIXED is the
// default setting for any other project type.", but link.exe defaults to
// /FIXED:NO for exe outputs as well. Match behavior, not docs.
bool fixed = args.hasFlag(OPT_fixed, OPT_fixed_no, false);
if (fixed) {
if (dynamicBaseArg &&
dynamicBaseArg->getOption().getID() == OPT_dynamicbase) {
error("/fixed must not be specified with /dynamicbase");
} else {
config->relocatable = false;
config->dynamicBase = false;
}
}
// Handle /appcontainer
config->appContainer =
args.hasFlag(OPT_appcontainer, OPT_appcontainer_no, false);
// Handle /machine
if (auto *arg = args.getLastArg(OPT_machine)) {
config->machine = getMachineType(arg->getValue());
if (config->machine == IMAGE_FILE_MACHINE_UNKNOWN)
fatal(Twine("unknown /machine argument: ") + arg->getValue());
}
// Handle /nodefaultlib:<filename>
for (auto *arg : args.filtered(OPT_nodefaultlib))
config->noDefaultLibs.insert(doFindLib(arg->getValue()).lower());
// Handle /nodefaultlib
if (args.hasArg(OPT_nodefaultlib_all))
config->noDefaultLibAll = true;
// Handle /base
if (auto *arg = args.getLastArg(OPT_base))
parseNumbers(arg->getValue(), &config->imageBase);
// Handle /filealign
if (auto *arg = args.getLastArg(OPT_filealign)) {
parseNumbers(arg->getValue(), &config->fileAlign);
if (!isPowerOf2_64(config->fileAlign))
error("/filealign: not a power of two: " + Twine(config->fileAlign));
}
// Handle /stack
if (auto *arg = args.getLastArg(OPT_stack))
parseNumbers(arg->getValue(), &config->stackReserve, &config->stackCommit);
// Handle /guard:cf
if (auto *arg = args.getLastArg(OPT_guard))
parseGuard(arg->getValue());
// Handle /heap
if (auto *arg = args.getLastArg(OPT_heap))
parseNumbers(arg->getValue(), &config->heapReserve, &config->heapCommit);
// Handle /version
if (auto *arg = args.getLastArg(OPT_version))
parseVersion(arg->getValue(), &config->majorImageVersion,
&config->minorImageVersion);
// Handle /subsystem
if (auto *arg = args.getLastArg(OPT_subsystem))
parseSubsystem(arg->getValue(), &config->subsystem, &config->majorOSVersion,
&config->minorOSVersion);
// Handle /timestamp
if (llvm::opt::Arg *arg = args.getLastArg(OPT_timestamp, OPT_repro)) {
if (arg->getOption().getID() == OPT_repro) {
config->timestamp = 0;
config->repro = true;
} else {
config->repro = false;
StringRef value(arg->getValue());
if (value.getAsInteger(0, config->timestamp))
fatal(Twine("invalid timestamp: ") + value +
". Expected 32-bit integer");
}
} else {
config->repro = false;
config->timestamp = time(nullptr);
}
// Handle /alternatename
for (auto *arg : args.filtered(OPT_alternatename))
parseAlternateName(arg->getValue());
// Handle /include
for (auto *arg : args.filtered(OPT_incl))
addUndefined(arg->getValue());
// Handle /implib
if (auto *arg = args.getLastArg(OPT_implib))
config->implib = arg->getValue();
// Handle /opt.
bool doGC = debug == DebugKind::None || args.hasArg(OPT_profile);
unsigned icfLevel =
args.hasArg(OPT_profile) ? 0 : 1; // 0: off, 1: limited, 2: on
unsigned tailMerge = 1;
for (auto *arg : args.filtered(OPT_opt)) {
std::string str = StringRef(arg->getValue()).lower();
SmallVector<StringRef, 1> vec;
StringRef(str).split(vec, ',');
for (StringRef s : vec) {
if (s == "ref") {
doGC = true;
} else if (s == "noref") {
doGC = false;
} else if (s == "icf" || s.startswith("icf=")) {
icfLevel = 2;
} else if (s == "noicf") {
icfLevel = 0;
} else if (s == "lldtailmerge") {
tailMerge = 2;
} else if (s == "nolldtailmerge") {
tailMerge = 0;
} else if (s.startswith("lldlto=")) {
StringRef optLevel = s.substr(7);
if (optLevel.getAsInteger(10, config->ltoo) || config->ltoo > 3)
error("/opt:lldlto: invalid optimization level: " + optLevel);
} else if (s.startswith("lldltojobs=")) {
StringRef jobs = s.substr(11);
if (jobs.getAsInteger(10, config->thinLTOJobs) ||
config->thinLTOJobs == 0)
error("/opt:lldltojobs: invalid job count: " + jobs);
} else if (s.startswith("lldltopartitions=")) {
StringRef n = s.substr(17);
if (n.getAsInteger(10, config->ltoPartitions) ||
config->ltoPartitions == 0)
error("/opt:lldltopartitions: invalid partition count: " + n);
} else if (s != "lbr" && s != "nolbr")
error("/opt: unknown option: " + s);
}
}
// Limited ICF is enabled if GC is enabled and ICF was never mentioned
// explicitly.
// FIXME: LLD only implements "limited" ICF, i.e. it only merges identical
// code. If the user passes /OPT:ICF explicitly, LLD should merge identical
// comdat readonly data.
if (icfLevel == 1 && !doGC)
icfLevel = 0;
config->doGC = doGC;
config->doICF = icfLevel > 0;
config->tailMerge = (tailMerge == 1 && config->doICF) || tailMerge == 2;
// Handle /lldsavetemps
if (args.hasArg(OPT_lldsavetemps))
config->saveTemps = true;
// Handle /kill-at
if (args.hasArg(OPT_kill_at))
config->killAt = true;
// Handle /lldltocache
if (auto *arg = args.getLastArg(OPT_lldltocache))
config->ltoCache = arg->getValue();
// Handle /lldsavecachepolicy
if (auto *arg = args.getLastArg(OPT_lldltocachepolicy))
config->ltoCachePolicy = CHECK(
parseCachePruningPolicy(arg->getValue()),
Twine("/lldltocachepolicy: invalid cache policy: ") + arg->getValue());
// Handle /failifmismatch
for (auto *arg : args.filtered(OPT_failifmismatch))
checkFailIfMismatch(arg->getValue(), nullptr);
// Handle /merge
for (auto *arg : args.filtered(OPT_merge))
parseMerge(arg->getValue());
// Add default section merging rules after user rules. User rules take
// precedence, but we will emit a warning if there is a conflict.
parseMerge(".idata=.rdata");
parseMerge(".didat=.rdata");
parseMerge(".edata=.rdata");
parseMerge(".xdata=.rdata");
parseMerge(".bss=.data");
if (config->mingw) {
parseMerge(".ctors=.rdata");
parseMerge(".dtors=.rdata");
parseMerge(".CRT=.rdata");
}
// Handle /section
for (auto *arg : args.filtered(OPT_section))
parseSection(arg->getValue());
// Handle /align
if (auto *arg = args.getLastArg(OPT_align)) {
parseNumbers(arg->getValue(), &config->align);
if (!isPowerOf2_64(config->align))
error("/align: not a power of two: " + StringRef(arg->getValue()));
}
// Handle /aligncomm
for (auto *arg : args.filtered(OPT_aligncomm))
parseAligncomm(arg->getValue());
// Handle /manifestdependency. This enables /manifest unless /manifest:no is
// also passed.
if (auto *arg = args.getLastArg(OPT_manifestdependency)) {
config->manifestDependency = arg->getValue();
config->manifest = Configuration::SideBySide;
}
// Handle /manifest and /manifest:
if (auto *arg = args.getLastArg(OPT_manifest, OPT_manifest_colon)) {
if (arg->getOption().getID() == OPT_manifest)
config->manifest = Configuration::SideBySide;
else
parseManifest(arg->getValue());
}
// Handle /manifestuac
if (auto *arg = args.getLastArg(OPT_manifestuac))
parseManifestUAC(arg->getValue());
// Handle /manifestfile
if (auto *arg = args.getLastArg(OPT_manifestfile))
config->manifestFile = arg->getValue();
// Handle /manifestinput
for (auto *arg : args.filtered(OPT_manifestinput))
config->manifestInput.push_back(arg->getValue());
if (!config->manifestInput.empty() &&
config->manifest != Configuration::Embed) {
fatal("/manifestinput: requires /manifest:embed");
}
config->thinLTOEmitImportsFiles = args.hasArg(OPT_thinlto_emit_imports_files);
config->thinLTOIndexOnly = args.hasArg(OPT_thinlto_index_only) ||
args.hasArg(OPT_thinlto_index_only_arg);
config->thinLTOIndexOnlyArg =
args.getLastArgValue(OPT_thinlto_index_only_arg);
config->thinLTOPrefixReplace =
getOldNewOptions(args, OPT_thinlto_prefix_replace);
config->thinLTOObjectSuffixReplace =
getOldNewOptions(args, OPT_thinlto_object_suffix_replace);
config->ltoObjPath = args.getLastArgValue(OPT_lto_obj_path);
// Handle miscellaneous boolean flags.
config->allowBind = args.hasFlag(OPT_allowbind, OPT_allowbind_no, true);
config->allowIsolation =
args.hasFlag(OPT_allowisolation, OPT_allowisolation_no, true);
config->incremental =
args.hasFlag(OPT_incremental, OPT_incremental_no,
!config->doGC && !config->doICF && !args.hasArg(OPT_order) &&
!args.hasArg(OPT_profile));
config->integrityCheck =
args.hasFlag(OPT_integritycheck, OPT_integritycheck_no, false);
config->nxCompat = args.hasFlag(OPT_nxcompat, OPT_nxcompat_no, true);
for (auto *arg : args.filtered(OPT_swaprun))
parseSwaprun(arg->getValue());
config->terminalServerAware =
!config->dll && args.hasFlag(OPT_tsaware, OPT_tsaware_no, true);
config->debugDwarf = debug == DebugKind::Dwarf;
config->debugGHashes = debug == DebugKind::GHash;
config->debugSymtab = debug == DebugKind::Symtab;
config->mapFile = getMapFile(args);
if (config->incremental && args.hasArg(OPT_profile)) {
warn("ignoring '/incremental' due to '/profile' specification");
config->incremental = false;
}
if (config->incremental && args.hasArg(OPT_order)) {
warn("ignoring '/incremental' due to '/order' specification");
config->incremental = false;
}
if (config->incremental && config->doGC) {
warn("ignoring '/incremental' because REF is enabled; use '/opt:noref' to "
"disable");
config->incremental = false;
}
if (config->incremental && config->doICF) {
warn("ignoring '/incremental' because ICF is enabled; use '/opt:noicf' to "
"disable");
config->incremental = false;
}
if (errorCount())
return;
std::set<sys::fs::UniqueID> wholeArchives;
for (auto *arg : args.filtered(OPT_wholearchive_file))
if (Optional<StringRef> path = doFindFile(arg->getValue()))
if (Optional<sys::fs::UniqueID> id = getUniqueID(*path))
wholeArchives.insert(*id);
// A predicate returning true if a given path is an argument for
// /wholearchive:, or /wholearchive is enabled globally.
// This function is a bit tricky because "foo.obj /wholearchive:././foo.obj"
// needs to be handled as "/wholearchive:foo.obj foo.obj".
auto isWholeArchive = [&](StringRef path) -> bool {
if (args.hasArg(OPT_wholearchive_flag))
return true;
if (Optional<sys::fs::UniqueID> id = getUniqueID(path))
return wholeArchives.count(*id);
return false;
};
// Create a list of input files. These can be given as OPT_INPUT options
// and OPT_wholearchive_file options, and we also need to track OPT_start_lib
// and OPT_end_lib.
bool inLib = false;
for (auto *arg : args) {
switch (arg->getOption().getID()) {
case OPT_end_lib:
if (!inLib)
error("stray " + arg->getSpelling());
inLib = false;
break;
case OPT_start_lib:
if (inLib)
error("nested " + arg->getSpelling());
inLib = true;
break;
case OPT_wholearchive_file:
if (Optional<StringRef> path = findFile(arg->getValue()))
enqueuePath(*path, true, inLib);
break;
case OPT_INPUT:
if (Optional<StringRef> path = findFile(arg->getValue()))
enqueuePath(*path, isWholeArchive(*path), inLib);
break;
default:
// Ignore other options.
break;
}
}
// Process files specified as /defaultlib. These should be enequeued after
// other files, which is why they are in a separate loop.
for (auto *arg : args.filtered(OPT_defaultlib))
if (Optional<StringRef> path = findLib(arg->getValue()))
enqueuePath(*path, false, false);
// Windows specific -- Create a resource file containing a manifest file.
if (config->manifest == Configuration::Embed)
addBuffer(createManifestRes(), false, false);
// Read all input files given via the command line.
run();
if (errorCount())
return;
// We should have inferred a machine type by now from the input files, but if
// not we assume x64.
if (config->machine == IMAGE_FILE_MACHINE_UNKNOWN) {
warn("/machine is not specified. x64 is assumed");
config->machine = AMD64;
}
config->wordsize = config->is64() ? 8 : 4;
// Handle /safeseh, x86 only, on by default, except for mingw.
if (config->machine == I386 &&
args.hasFlag(OPT_safeseh, OPT_safeseh_no, !config->mingw))
config->safeSEH = true;
// Handle /functionpadmin
for (auto *arg : args.filtered(OPT_functionpadmin, OPT_functionpadmin_opt))
parseFunctionPadMin(arg, config->machine);
if (tar)
tar->append("response.txt",
createResponseFile(args, filePaths,
ArrayRef<StringRef>(searchPaths).slice(1)));
// Handle /largeaddressaware
config->largeAddressAware = args.hasFlag(
OPT_largeaddressaware, OPT_largeaddressaware_no, config->is64());
// Handle /highentropyva
config->highEntropyVA =
config->is64() &&
args.hasFlag(OPT_highentropyva, OPT_highentropyva_no, true);
if (!config->dynamicBase &&
(config->machine == ARMNT || config->machine == ARM64))
error("/dynamicbase:no is not compatible with " +
machineToStr(config->machine));
// Handle /export
for (auto *arg : args.filtered(OPT_export)) {
Export e = parseExport(arg->getValue());
if (config->machine == I386) {
if (!isDecorated(e.name))
e.name = saver.save("_" + e.name);
if (!e.extName.empty() && !isDecorated(e.extName))
e.extName = saver.save("_" + e.extName);
}
config->exports.push_back(e);
}
// Handle /def
if (auto *arg = args.getLastArg(OPT_deffile)) {
// parseModuleDefs mutates Config object.
parseModuleDefs(arg->getValue());
}
// Handle generation of import library from a def file.
if (!args.hasArg(OPT_INPUT)) {
fixupExports();
createImportLibrary(/*asLib=*/true);
return;
}
// Windows specific -- if no /subsystem is given, we need to infer
// that from entry point name. Must happen before /entry handling,
// and after the early return when just writing an import library.
if (config->subsystem == IMAGE_SUBSYSTEM_UNKNOWN) {
config->subsystem = inferSubsystem();
if (config->subsystem == IMAGE_SUBSYSTEM_UNKNOWN)
fatal("subsystem must be defined");
}
// Handle /entry and /dll
if (auto *arg = args.getLastArg(OPT_entry)) {
config->entry = addUndefined(mangle(arg->getValue()));
} else if (!config->entry && !config->noEntry) {
if (args.hasArg(OPT_dll)) {
StringRef s = (config->machine == I386) ? "__DllMainCRTStartup@12"
: "_DllMainCRTStartup";
config->entry = addUndefined(s);
} else {
// Windows specific -- If entry point name is not given, we need to
// infer that from user-defined entry name.
StringRef s = findDefaultEntry();
if (s.empty())
fatal("entry point must be defined");
config->entry = addUndefined(s);
log("Entry name inferred: " + s);
}
}
// Handle /delayload
for (auto *arg : args.filtered(OPT_delayload)) {
config->delayLoads.insert(StringRef(arg->getValue()).lower());
if (config->machine == I386) {
config->delayLoadHelper = addUndefined("___delayLoadHelper2@8");
} else {
config->delayLoadHelper = addUndefined("__delayLoadHelper2");
}
}
// Set default image name if neither /out or /def set it.
if (config->outputFile.empty()) {
config->outputFile =
getOutputPath((*args.filtered(OPT_INPUT).begin())->getValue());
}
// Fail early if an output file is not writable.
if (auto e = tryCreateFile(config->outputFile)) {
error("cannot open output file " + config->outputFile + ": " + e.message());
return;
}
if (shouldCreatePDB) {
// Put the PDB next to the image if no /pdb flag was passed.
if (config->pdbPath.empty()) {
config->pdbPath = config->outputFile;
sys::path::replace_extension(config->pdbPath, ".pdb");
}
// The embedded PDB path should be the absolute path to the PDB if no
// /pdbaltpath flag was passed.
if (config->pdbAltPath.empty()) {
config->pdbAltPath = config->pdbPath;
// It's important to make the path absolute and remove dots. This path
// will eventually be written into the PE header, and certain Microsoft
// tools won't work correctly if these assumptions are not held.
sys::fs::make_absolute(config->pdbAltPath);
sys::path::remove_dots(config->pdbAltPath);
} else {
// Don't do this earlier, so that Config->OutputFile is ready.
parsePDBAltPath(config->pdbAltPath);
}
}
// Set default image base if /base is not given.
if (config->imageBase == uint64_t(-1))
config->imageBase = getDefaultImageBase();
symtab->addSynthetic(mangle("__ImageBase"), nullptr);
if (config->machine == I386) {
symtab->addAbsolute("___safe_se_handler_table", 0);
symtab->addAbsolute("___safe_se_handler_count", 0);
}
symtab->addAbsolute(mangle("__guard_fids_count"), 0);
symtab->addAbsolute(mangle("__guard_fids_table"), 0);
symtab->addAbsolute(mangle("__guard_flags"), 0);
symtab->addAbsolute(mangle("__guard_iat_count"), 0);
symtab->addAbsolute(mangle("__guard_iat_table"), 0);
symtab->addAbsolute(mangle("__guard_longjmp_count"), 0);
symtab->addAbsolute(mangle("__guard_longjmp_table"), 0);
// Needed for MSVC 2017 15.5 CRT.
symtab->addAbsolute(mangle("__enclave_config"), 0);
if (config->mingw) {
symtab->addAbsolute(mangle("__RUNTIME_PSEUDO_RELOC_LIST__"), 0);
symtab->addAbsolute(mangle("__RUNTIME_PSEUDO_RELOC_LIST_END__"), 0);
symtab->addAbsolute(mangle("__CTOR_LIST__"), 0);
symtab->addAbsolute(mangle("__DTOR_LIST__"), 0);
}
// This code may add new undefined symbols to the link, which may enqueue more
// symbol resolution tasks, so we need to continue executing tasks until we
// converge.
do {
// Windows specific -- if entry point is not found,
// search for its mangled names.
if (config->entry)
mangleMaybe(config->entry);
// Windows specific -- Make sure we resolve all dllexported symbols.
for (Export &e : config->exports) {
if (!e.forwardTo.empty())
continue;
e.sym = addUndefined(e.name);
if (!e.directives)
e.symbolName = mangleMaybe(e.sym);
}
// Add weak aliases. Weak aliases is a mechanism to give remaining
// undefined symbols final chance to be resolved successfully.
for (auto pair : config->alternateNames) {
StringRef from = pair.first;
StringRef to = pair.second;
Symbol *sym = symtab->find(from);
if (!sym)
continue;
if (auto *u = dyn_cast<Undefined>(sym))
if (!u->weakAlias)
u->weakAlias = symtab->addUndefined(to);
}
// If any inputs are bitcode files, the LTO code generator may create
// references to library functions that are not explicit in the bitcode
// file's symbol table. If any of those library functions are defined in a
// bitcode file in an archive member, we need to arrange to use LTO to
// compile those archive members by adding them to the link beforehand.
if (!BitcodeFile::instances.empty())
for (auto *s : lto::LTO::getRuntimeLibcallSymbols())
symtab->addLibcall(s);
// Windows specific -- if __load_config_used can be resolved, resolve it.
if (symtab->findUnderscore("_load_config_used"))
addUndefined(mangle("_load_config_used"));
} while (run());
if (args.hasArg(OPT_include_optional)) {
// Handle /includeoptional
for (auto *arg : args.filtered(OPT_include_optional))
if (dyn_cast_or_null<LazyArchive>(symtab->find(arg->getValue())))
addUndefined(arg->getValue());
while (run());
}
if (config->mingw) {
// Load any further object files that might be needed for doing automatic
// imports.
//
// For cases with no automatically imported symbols, this iterates once
// over the symbol table and doesn't do anything.
//
// For the normal case with a few automatically imported symbols, this
// should only need to be run once, since each new object file imported
// is an import library and wouldn't add any new undefined references,
// but there's nothing stopping the __imp_ symbols from coming from a
// normal object file as well (although that won't be used for the
// actual autoimport later on). If this pass adds new undefined references,
// we won't iterate further to resolve them.
symtab->loadMinGWAutomaticImports();
run();
}
// At this point, we should not have any symbols that cannot be resolved.
// If we are going to do codegen for link-time optimization, check for
// unresolvable symbols first, so we don't spend time generating code that
// will fail to link anyway.
if (!BitcodeFile::instances.empty() && !config->forceUnresolved)
symtab->reportUnresolvable();
if (errorCount())
return;
// Do LTO by compiling bitcode input files to a set of native COFF files then
// link those files (unless -thinlto-index-only was given, in which case we
// resolve symbols and write indices, but don't generate native code or link).
symtab->addCombinedLTOObjects();
// If -thinlto-index-only is given, we should create only "index
// files" and not object files. Index file creation is already done
// in addCombinedLTOObject, so we are done if that's the case.
if (config->thinLTOIndexOnly)
return;
// If we generated native object files from bitcode files, this resolves
// references to the symbols we use from them.
run();
// Resolve remaining undefined symbols and warn about imported locals.
symtab->resolveRemainingUndefines();
if (errorCount())
return;
config->hadExplicitExports = !config->exports.empty();
if (config->mingw) {
// In MinGW, all symbols are automatically exported if no symbols
// are chosen to be exported.
maybeExportMinGWSymbols(args);
// Make sure the crtend.o object is the last object file. This object
// file can contain terminating section chunks that need to be placed
// last. GNU ld processes files and static libraries explicitly in the
// order provided on the command line, while lld will pull in needed
// files from static libraries only after the last object file on the
// command line.
for (auto i = ObjFile::instances.begin(), e = ObjFile::instances.end();
i != e; i++) {
ObjFile *file = *i;
if (isCrtend(file->getName())) {
ObjFile::instances.erase(i);
ObjFile::instances.push_back(file);
break;
}
}
}
// Windows specific -- when we are creating a .dll file, we also
// need to create a .lib file. In MinGW mode, we only do that when the
// -implib option is given explicitly, for compatibility with GNU ld.
if (!config->exports.empty() || config->dll) {
fixupExports();
if (!config->mingw || !config->implib.empty())
createImportLibrary(/*asLib=*/false);
assignExportOrdinals();
}
// Handle /output-def (MinGW specific).
if (auto *arg = args.getLastArg(OPT_output_def))
writeDefFile(arg->getValue());
// Set extra alignment for .comm symbols
for (auto pair : config->alignComm) {
StringRef name = pair.first;
uint32_t alignment = pair.second;
Symbol *sym = symtab->find(name);
if (!sym) {
warn("/aligncomm symbol " + name + " not found");
continue;
}
// If the symbol isn't common, it must have been replaced with a regular
// symbol, which will carry its own alignment.
auto *dc = dyn_cast<DefinedCommon>(sym);
if (!dc)
continue;
CommonChunk *c = dc->getChunk();
c->setAlignment(std::max(c->getAlignment(), alignment));
}
// Windows specific -- Create a side-by-side manifest file.
if (config->manifest == Configuration::SideBySide)
createSideBySideManifest();
// Handle /order. We want to do this at this moment because we
// need a complete list of comdat sections to warn on nonexistent
// functions.
if (auto *arg = args.getLastArg(OPT_order))
parseOrderFile(arg->getValue());
// Identify unreferenced COMDAT sections.
if (config->doGC)
markLive(symtab->getChunks());
// Needs to happen after the last call to addFile().
convertResources();
// Identify identical COMDAT sections to merge them.
if (config->doICF) {
findKeepUniqueSections();
doICF(symtab->getChunks());
}
// Write the result.
writeResult();
// Stop early so we can print the results.
Timer::root().stop();
if (config->showTiming)
Timer::root().print();
}
} // namespace coff
} // namespace lld
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