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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/CommandLine.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 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 &stdoutOS,
raw_ostream &stderrOS) {
lld::stdoutOS = &stdoutOS;
lld::stderrOS = &stderrOS;
errorHandler().logName = args::getFilenameWithoutExe(args[0]);
errorHandler().errorLimitExceededMsg =
"too many errors emitted, stopping now"
" (use /errorlimit:0 to see all errors)";
errorHandler().exitEarly = canExitEarly;
stderrOS.enable_colors(stderrOS.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", ".dll" or ".sys".
static std::string getOutputPath(StringRef path) {
StringRef ext = ".exe";
if (config->dll)
ext = ".dll";
else if (config->driver)
ext = ".sys";
return (sys::path::stem(path) + ext).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_reproduce:
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 calculated as follows:
//
// | 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 " +