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llvm-project/lld/COFF/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/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[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>();
Config->Argv = {Args.begin(), Args.end()};
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();
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()};
});
}
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;
}
// 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");
return doFindFile(Filename);
}
// 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;
}
// Symbol names are mangled by appending "_" prefix on x86.
StringRef LinkerDriver::mangle(StringRef Sym) {
assert(Config->Machine != IMAGE_FILE_MACHINE_UNKNOWN);
if (Config->Machine == I386)
return Saver.save("_" + Sym);
return Sym;
}
// 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() {
// As a special case, if /nodefaultlib is given, we directly look for an
// entry point. This is because, if no default library is linked, users
// need to define an entry point instead of a "main".
if (Config->NoDefaultLibAll) {
for (StringRef S : {"mainCRTStartup", "wmainCRTStartup",
"WinMainCRTStartup", "wWinMainCRTStartup"}) {
StringRef Entry = Symtab->findMangle(S);
if (!Entry.empty() && !isa<Undefined>(Symtab->find(Entry)))
return mangle(S);
}
return "";
}
// User-defined main functions and their corresponding entry points.
static const char *Entries[][2] = {
{"main", "mainCRTStartup"},
{"wmain", "wmainCRTStartup"},
{"WinMain", "WinMainCRTStartup"},
{"wWinMain", "wWinMainCRTStartup"},
};
for (auto E : Entries) {
StringRef Entry = Symtab->findMangle(mangle(E[0]));
if (!Entry.empty() && !isa<Undefined>(Symtab->find(Entry)))
return mangle(E[1]);
}
return "";
}
WindowsSubsystem LinkerDriver::inferSubsystem() {
if (Config->DLL)
return IMAGE_SUBSYSTEM_WINDOWS_GUI;
if (Symtab->findUnderscore("main") || Symtab->findUnderscore("wmain"))
return IMAGE_SUBSYSTEM_WINDOWS_CUI;
if (Symtab->findUnderscore("WinMain") || Symtab->findUnderscore("wWinMain"))
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();
}
static unsigned getDefaultDebugType(const opt::InputArgList &Args) {
unsigned 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 unsigned parseDebugType(StringRef Arg) {
SmallVector<StringRef, 3> Types;
Arg.split(Types, ',', /*KeepEmpty=*/false);
unsigned DebugTypes = static_cast<unsigned>(DebugType::None);
for (StringRef Type : Types)
DebugTypes |= 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);
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);
}
}
// A helper function for filterBitcodeFiles.
static bool needsRebuilding(MemoryBufferRef MB) {
// The MSVC linker doesn't support thin archives, so if it's a thin
// archive, we always need to rebuild it.
std::unique_ptr<Archive> File =
CHECK(Archive::create(MB), "Failed to read " + MB.getBufferIdentifier());
if (File->isThin())
return true;
// Returns true if the archive contains at least one bitcode file.
for (MemoryBufferRef Member : getArchiveMembers(File.get()))
if (identify_magic(Member.getBuffer()) == file_magic::bitcode)
return true;
return false;
}
// Opens a given path as an archive file and removes bitcode files
// from them if exists. This function is to appease the MSVC linker as
// their linker doesn't like archive files containing non-native
// object files.
//
// If a given archive doesn't contain bitcode files, the archive path
// is returned as-is. Otherwise, a new temporary file is created and
// its path is returned.
static Optional<std::string>
filterBitcodeFiles(StringRef Path, std::vector<std::string> &TemporaryFiles) {
std::unique_ptr<MemoryBuffer> MB = CHECK(
MemoryBuffer::getFile(Path, -1, false, true), "could not open " + Path);
MemoryBufferRef MBRef = MB->getMemBufferRef();
file_magic Magic = identify_magic(MBRef.getBuffer());
if (Magic == file_magic::bitcode)
return None;
if (Magic != file_magic::archive)
return Path.str();
if (!needsRebuilding(MBRef))
return Path.str();
std::unique_ptr<Archive> File =
CHECK(Archive::create(MBRef),
MBRef.getBufferIdentifier() + ": failed to parse archive");
std::vector<NewArchiveMember> New;
for (MemoryBufferRef Member : getArchiveMembers(File.get()))
if (identify_magic(Member.getBuffer()) != file_magic::bitcode)
New.emplace_back(Member);
if (New.empty())
return None;
log("Creating a temporary archive for " + Path + " to remove bitcode files");
SmallString<128> S;
if (std::error_code EC = sys::fs::createTemporaryFile(
"lld-" + sys::path::stem(Path), ".lib", S))
fatal("cannot create a temporary file: " + EC.message());
std::string Temp = S.str();
TemporaryFiles.push_back(Temp);
Error E =
llvm::writeArchive(Temp, New, /*WriteSymtab=*/true, Archive::Kind::K_GNU,
/*Deterministics=*/true,
/*Thin=*/false);
handleAllErrors(std::move(E), [&](const ErrorInfoBase &EI) {
error("failed to create a new archive " + S.str() + ": " + EI.message());
});
return Temp;
}
// Create response file contents and invoke the MSVC linker.
void LinkerDriver::invokeMSVC(opt::InputArgList &Args) {
std::string Rsp = "/nologo\n";
std::vector<std::string> Temps;
// Write out archive members that we used in symbol resolution and pass these
// to MSVC before any archives, so that MSVC uses the same objects to satisfy
// references.
for (ObjFile *Obj : ObjFile::Instances) {
if (Obj->ParentName.empty())
continue;
SmallString<128> S;
int Fd;
if (auto EC = sys::fs::createTemporaryFile(
"lld-" + sys::path::filename(Obj->ParentName), ".obj", Fd, S))
fatal("cannot create a temporary file: " + EC.message());
raw_fd_ostream OS(Fd, /*shouldClose*/ true);
OS << Obj->MB.getBuffer();
Temps.push_back(S.str());
Rsp += quote(S) + "\n";
}
for (auto *Arg : Args) {
switch (Arg->getOption().getID()) {
case OPT_linkrepro:
case OPT_lldmap:
case OPT_lldmap_file:
case OPT_lldsavetemps:
case OPT_msvclto:
// LLD-specific options are stripped.
break;
case OPT_opt:
if (!StringRef(Arg->getValue()).startswith("lld"))
Rsp += toString(*Arg) + " ";
break;
case OPT_INPUT: {
if (Optional<StringRef> Path = doFindFile(Arg->getValue())) {
if (Optional<std::string> S = filterBitcodeFiles(*Path, Temps))
Rsp += quote(*S) + "\n";
continue;
}
Rsp += quote(Arg->getValue()) + "\n";
break;
}
default:
Rsp += toString(*Arg) + "\n";
}
}
std::vector<StringRef> ObjFiles = Symtab->compileBitcodeFiles();
runMSVCLinker(Rsp, ObjFiles);
for (StringRef Path : Temps)
sys::fs::remove(Path);
}
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();
}
}
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.slice(1));
// 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)) {
if (StringRef(Arg->getValue()) == "4037")
Config->WarnMissingOrderSymbol = false;
else if (StringRef(Arg->getValue()) == "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->Force = true;
// Handle /debug
if (Args.hasArg(OPT_debug, OPT_debug_dwarf, OPT_debug_ghash)) {
Config->Debug = true;
Config->Incremental = true;
if (auto *Arg = Args.getLastArg(OPT_debugtype))
Config->DebugTypes = parseDebugType(Arg->getValue());
else
Config->DebugTypes = getDefaultDebugType(Args);
}
// Handle /pdb
bool ShouldCreatePDB = Args.hasArg(OPT_debug, OPT_debug_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());
// Handle /nodefaultlib:<filename>
for (auto *Arg : Args.filtered(OPT_nodefaultlib))
Config->NoDefaultLibs.insert(doFindLib(Arg->getValue()));
// 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 /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 = !Args.hasArg(OPT_debug) || 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());
// 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");
// Handle /section
for (auto *Arg : Args.filtered(OPT_section))
parseSection(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");
}
// 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);
Config->TerminalServerAware =
!Config->DLL && Args.hasFlag(OPT_tsaware, OPT_tsaware_no, true);
Config->DebugDwarf = Args.hasArg(OPT_debug_dwarf);
Config->DebugGHashes = Args.hasArg(OPT_debug_ghash);
Config->DebugSymtab = Args.hasArg(OPT_debug_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. Files can be given as arguments
// for /defaultlib option.
for (auto *Arg : Args.filtered(OPT_INPUT, OPT_wholearchive_file))
if (Optional<StringRef> Path = findFile(Arg->getValue()))
enqueuePath(*Path, IsWholeArchive(*Path));
for (auto *Arg : Args.filtered(OPT_defaultlib))
if (Optional<StringRef> Path = findLib(Arg->getValue()))
enqueuePath(*Path, false);
// Windows specific -- Create a resource file containing a manifest file.
if (Config->Manifest == Configuration::Embed)
addBuffer(createManifestRes(), false);
// Read all input files given via the command line.
run();
// 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;
}
// Input files can be Windows resource files (.res files). We use
// WindowsResource to convert resource files to a regular COFF file,
// then link the resulting file normally.
if (!Resources.empty())
Symtab->addFile(make<ObjFile>(convertResToCOFF(Resources)));
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 /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 /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;
}
// 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());
}
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);
}
}
// 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);
// 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)
Symtab->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)
Symtab->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);
}
// 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 (errorCount())
return;
// If /msvclto is given, we use the MSVC linker to link LTO output files.
// This is useful because MSVC link.exe can generate complete PDBs.
if (Args.hasArg(OPT_msvclto)) {
invokeMSVC(Args);
return;
}
// Do LTO by compiling bitcode input files to a set of native COFF files then
// link those files.
Symtab->addCombinedLTOObjects();
run();
// Make sure we have resolved all symbols.
Symtab->reportRemainingUndefines();
if (errorCount())
return;
// Windows specific -- if no /subsystem is given, we need to infer
// that from entry point name.
if (Config->Subsystem == IMAGE_SUBSYSTEM_UNKNOWN) {
Config->Subsystem = inferSubsystem();
if (Config->Subsystem == IMAGE_SUBSYSTEM_UNKNOWN)
fatal("subsystem must be defined");
}
// Handle /safeseh.
if (Args.hasFlag(OPT_safeseh, OPT_safeseh_no, false)) {
for (ObjFile *File : ObjFile::Instances)
if (!File->hasSafeSEH())
error("/safeseh: " + File->getName() + " is not compatible with SEH");
if (errorCount())
return;
}
// In MinGW, all symbols are automatically exported if no symbols
// are chosen to be exported.
if (Config->DLL && ((Config->MinGW && Config->Exports.empty()) ||
Args.hasArg(OPT_export_all_symbols))) {
AutoExporter Exporter;
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 (Def->getChunk() &&
!(Def->getChunk()->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE))
E.Data = true;
Config->Exports.push_back(E);
});
}
// Windows specific -- when we are creating a .dll file, we also
// need to create a .lib file.
if (!Config->Exports.empty() || Config->DLL) {
fixupExports();
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;
}
auto *DC = dyn_cast<DefinedCommon>(Sym);
if (!DC) {
warn("/aligncomm symbol " + Name + " of wrong kind");
continue;
}
CommonChunk *C = DC->getChunk();
C->Alignment = std::max(C->Alignment, 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());
// Identify identical COMDAT sections to merge them.
if (Config->DoICF)
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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