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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
//
//===----------------------------------------------------------------------===//
//
// The driver drives the entire linking process. It is responsible for
// parsing command line options and doing whatever it is instructed to do.
//
// One notable thing in the LLD's driver when compared to other linkers is
// that the LLD's driver is agnostic on the host operating system.
// Other linkers usually have implicit default values (such as a dynamic
// linker path or library paths) for each host OS.
//
// I don't think implicit default values are useful because they are
// usually explicitly specified by the compiler ctx.driver. They can even
// be harmful when you are doing cross-linking. Therefore, in LLD, we
// simply trust the compiler driver to pass all required options and
// don't try to make effort on our side.
//
//===----------------------------------------------------------------------===//
#include "Driver.h"
#include "Config.h"
#include "ICF.h"
#include "InputFiles.h"
#include "InputSection.h"
#include "LTO.h"
#include "LinkerScript.h"
#include "MarkLive.h"
#include "OutputSections.h"
#include "ScriptParser.h"
#include "SymbolTable.h"
#include "Symbols.h"
#include "SyntheticSections.h"
#include "Target.h"
#include "Writer.h"
#include "lld/Common/Args.h"
#include "lld/Common/CommonLinkerContext.h"
#include "lld/Common/Driver.h"
#include "lld/Common/ErrorHandler.h"
#include "lld/Common/Filesystem.h"
#include "lld/Common/Memory.h"
#include "lld/Common/Strings.h"
#include "lld/Common/TargetOptionsCommandFlags.h"
#include "lld/Common/Version.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/LTO/LTO.h"
#include "llvm/Object/Archive.h"
#include "llvm/Object/IRObjectFile.h"
#include "llvm/Remarks/HotnessThresholdParser.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/Compression.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/GlobPattern.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/Parallel.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/TarWriter.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/TimeProfiler.h"
#include "llvm/Support/raw_ostream.h"
#include <cstdlib>
#include <tuple>
#include <utility>
using namespace llvm;
using namespace llvm::ELF;
using namespace llvm::object;
using namespace llvm::sys;
using namespace llvm::support;
using namespace lld;
using namespace lld::elf;
static void setConfigs(Ctx &ctx, opt::InputArgList &args);
static void readConfigs(Ctx &ctx, opt::InputArgList &args);
ELFSyncStream elf::Log(Ctx &ctx) { return {ctx, DiagLevel::Log}; }
ELFSyncStream elf::Msg(Ctx &ctx) { return {ctx, DiagLevel::Msg}; }
ELFSyncStream elf::Warn(Ctx &ctx) { return {ctx, DiagLevel::Warn}; }
ELFSyncStream elf::Err(Ctx &ctx) {
return {ctx, ctx.arg.noinhibitExec ? DiagLevel::Warn : DiagLevel::Err};
}
ELFSyncStream elf::ErrAlways(Ctx &ctx) { return {ctx, DiagLevel::Err}; }
ELFSyncStream elf::Fatal(Ctx &ctx) { return {ctx, DiagLevel::Fatal}; }
uint64_t elf::errCount(Ctx &ctx) { return ctx.e.errorCount; }
ELFSyncStream elf::InternalErr(Ctx &ctx, const uint8_t *buf) {
ELFSyncStream s(ctx, DiagLevel::Err);
s << "internal linker error: ";
return s;
}
Ctx::Ctx() : driver(*this) {}
llvm::raw_fd_ostream Ctx::openAuxiliaryFile(llvm::StringRef filename,
std::error_code &ec) {
using namespace llvm::sys::fs;
OpenFlags flags =
auxiliaryFiles.insert(filename).second ? OF_None : OF_Append;
return {filename, ec, flags};
}
namespace lld {
namespace elf {
bool link(ArrayRef<const char *> args, llvm::raw_ostream &stdoutOS,
llvm::raw_ostream &stderrOS, bool exitEarly, bool disableOutput) {
// This driver-specific context will be freed later by unsafeLldMain().
auto *context = new Ctx;
Ctx &ctx = *context;
context->e.initialize(stdoutOS, stderrOS, exitEarly, disableOutput);
context->e.logName = args::getFilenameWithoutExe(args[0]);
context->e.errorLimitExceededMsg =
"too many errors emitted, stopping now (use "
"--error-limit=0 to see all errors)";
LinkerScript script(ctx);
ctx.script = &script;
ctx.symAux.emplace_back();
ctx.symtab = std::make_unique<SymbolTable>(ctx);
ctx.partitions.clear();
ctx.partitions.emplace_back(ctx);
ctx.arg.progName = args[0];
ctx.driver.linkerMain(args);
return errCount(ctx) == 0;
}
} // namespace elf
} // namespace lld
// Parses a linker -m option.
static std::tuple<ELFKind, uint16_t, uint8_t> parseEmulation(Ctx &ctx,
StringRef emul) {
uint8_t osabi = 0;
StringRef s = emul;
if (s.ends_with("_fbsd")) {
s = s.drop_back(5);
osabi = ELFOSABI_FREEBSD;
}
std::pair<ELFKind, uint16_t> ret =
StringSwitch<std::pair<ELFKind, uint16_t>>(s)
.Cases("aarch64elf", "aarch64linux", {ELF64LEKind, EM_AARCH64})
.Cases("aarch64elfb", "aarch64linuxb", {ELF64BEKind, EM_AARCH64})
.Cases("armelf", "armelf_linux_eabi", {ELF32LEKind, EM_ARM})
.Cases("armelfb", "armelfb_linux_eabi", {ELF32BEKind, EM_ARM})
.Case("elf32_x86_64", {ELF32LEKind, EM_X86_64})
.Cases("elf32btsmip", "elf32btsmipn32", {ELF32BEKind, EM_MIPS})
.Cases("elf32ltsmip", "elf32ltsmipn32", {ELF32LEKind, EM_MIPS})
.Case("elf32lriscv", {ELF32LEKind, EM_RISCV})
.Cases("elf32ppc", "elf32ppclinux", {ELF32BEKind, EM_PPC})
.Cases("elf32lppc", "elf32lppclinux", {ELF32LEKind, EM_PPC})
.Case("elf32loongarch", {ELF32LEKind, EM_LOONGARCH})
.Case("elf64btsmip", {ELF64BEKind, EM_MIPS})
.Case("elf64ltsmip", {ELF64LEKind, EM_MIPS})
.Case("elf64lriscv", {ELF64LEKind, EM_RISCV})
.Case("elf64ppc", {ELF64BEKind, EM_PPC64})
.Case("elf64lppc", {ELF64LEKind, EM_PPC64})
.Cases("elf_amd64", "elf_x86_64", {ELF64LEKind, EM_X86_64})
.Case("elf_i386", {ELF32LEKind, EM_386})
.Case("elf_iamcu", {ELF32LEKind, EM_IAMCU})
.Case("elf64_sparc", {ELF64BEKind, EM_SPARCV9})
.Case("msp430elf", {ELF32LEKind, EM_MSP430})
.Case("elf64_amdgpu", {ELF64LEKind, EM_AMDGPU})
.Case("elf64loongarch", {ELF64LEKind, EM_LOONGARCH})
.Case("elf64_s390", {ELF64BEKind, EM_S390})
.Case("hexagonelf", {ELF32LEKind, EM_HEXAGON})
.Default({ELFNoneKind, EM_NONE});
if (ret.first == ELFNoneKind)
ErrAlways(ctx) << "unknown emulation: " << emul;
if (ret.second == EM_MSP430)
osabi = ELFOSABI_STANDALONE;
else if (ret.second == EM_AMDGPU)
osabi = ELFOSABI_AMDGPU_HSA;
return std::make_tuple(ret.first, ret.second, osabi);
}
// Returns slices of MB by parsing MB as an archive file.
// Each slice consists of a member file in the archive.
std::vector<std::pair<MemoryBufferRef, uint64_t>> static getArchiveMembers(
Ctx &ctx, MemoryBufferRef mb) {
std::unique_ptr<Archive> file =
CHECK(Archive::create(mb),
mb.getBufferIdentifier() + ": failed to parse archive");
std::vector<std::pair<MemoryBufferRef, uint64_t>> v;
Error err = Error::success();
bool addToTar = file->isThin() && ctx.tar;
for (const Archive::Child &c : file->children(err)) {
MemoryBufferRef mbref =
CHECK(c.getMemoryBufferRef(),
mb.getBufferIdentifier() +
": could not get the buffer for a child of the archive");
if (addToTar)
ctx.tar->append(relativeToRoot(check(c.getFullName())),
mbref.getBuffer());
v.push_back(std::make_pair(mbref, c.getChildOffset()));
}
if (err)
Fatal(ctx) << mb.getBufferIdentifier()
<< ": Archive::children failed: " << std::move(err);
// Take ownership of memory buffers created for members of thin archives.
std::vector<std::unique_ptr<MemoryBuffer>> mbs = file->takeThinBuffers();
std::move(mbs.begin(), mbs.end(), std::back_inserter(ctx.memoryBuffers));
return v;
}
static bool isBitcode(MemoryBufferRef mb) {
return identify_magic(mb.getBuffer()) == llvm::file_magic::bitcode;
}
bool LinkerDriver::tryAddFatLTOFile(MemoryBufferRef mb, StringRef archiveName,
uint64_t offsetInArchive, bool lazy) {
if (!ctx.arg.fatLTOObjects)
return false;
Expected<MemoryBufferRef> fatLTOData =
IRObjectFile::findBitcodeInMemBuffer(mb);
if (errorToBool(fatLTOData.takeError()))
return false;
files.push_back(std::make_unique<BitcodeFile>(ctx, *fatLTOData, archiveName,
offsetInArchive, lazy));
return true;
}
// Opens a file and create a file object. Path has to be resolved already.
void LinkerDriver::addFile(StringRef path, bool withLOption) {
using namespace sys::fs;
std::optional<MemoryBufferRef> buffer = readFile(ctx, path);
if (!buffer)
return;
MemoryBufferRef mbref = *buffer;
if (ctx.arg.formatBinary) {
files.push_back(std::make_unique<BinaryFile>(ctx, mbref));
return;
}
switch (identify_magic(mbref.getBuffer())) {
case file_magic::unknown:
readLinkerScript(ctx, mbref);
return;
case file_magic::archive: {
auto members = getArchiveMembers(ctx, mbref);
if (inWholeArchive) {
for (const std::pair<MemoryBufferRef, uint64_t> &p : members) {
if (isBitcode(p.first))
files.push_back(std::make_unique<BitcodeFile>(ctx, p.first, path,
p.second, false));
else if (!tryAddFatLTOFile(p.first, path, p.second, false))
files.push_back(createObjFile(ctx, p.first, path));
}
return;
}
archiveFiles.emplace_back(path, members.size());
// Handle archives and --start-lib/--end-lib using the same code path. This
// scans all the ELF relocatable object files and bitcode files in the
// archive rather than just the index file, with the benefit that the
// symbols are only loaded once. For many projects archives see high
// utilization rates and it is a net performance win. --start-lib scans
// symbols in the same order that llvm-ar adds them to the index, so in the
// common case the semantics are identical. If the archive symbol table was
// created in a different order, or is incomplete, this strategy has
// different semantics. Such output differences are considered user error.
//
// All files within the archive get the same group ID to allow mutual
// references for --warn-backrefs.
SaveAndRestore saved(isInGroup, true);
for (const std::pair<MemoryBufferRef, uint64_t> &p : members) {
auto magic = identify_magic(p.first.getBuffer());
if (magic == file_magic::elf_relocatable) {
if (!tryAddFatLTOFile(p.first, path, p.second, true))
files.push_back(createObjFile(ctx, p.first, path, true));
} else if (magic == file_magic::bitcode)
files.push_back(
std::make_unique<BitcodeFile>(ctx, p.first, path, p.second, true));
else
Warn(ctx) << path << ": archive member '"
<< p.first.getBufferIdentifier()
<< "' is neither ET_REL nor LLVM bitcode";
}
if (!saved.get())
++nextGroupId;
return;
}
case file_magic::elf_shared_object: {
if (ctx.arg.isStatic) {
ErrAlways(ctx) << "attempted static link of dynamic object " << path;
return;
}
// Shared objects are identified by soname. soname is (if specified)
// DT_SONAME and falls back to filename. If a file was specified by -lfoo,
// the directory part is ignored. Note that path may be a temporary and
// cannot be stored into SharedFile::soName.
path = mbref.getBufferIdentifier();
auto f = std::make_unique<SharedFile>(
ctx, mbref, withLOption ? path::filename(path) : path);
f->init();
files.push_back(std::move(f));
return;
}
case file_magic::bitcode:
files.push_back(std::make_unique<BitcodeFile>(ctx, mbref, "", 0, inLib));
break;
case file_magic::elf_relocatable:
if (!tryAddFatLTOFile(mbref, "", 0, inLib))
files.push_back(createObjFile(ctx, mbref, "", inLib));
break;
default:
ErrAlways(ctx) << path << ": unknown file type";
}
}
// Add a given library by searching it from input search paths.
void LinkerDriver::addLibrary(StringRef name) {
if (std::optional<std::string> path = searchLibrary(ctx, name))
addFile(ctx.saver.save(*path), /*withLOption=*/true);
else
ctx.e.error("unable to find library -l" + name, ErrorTag::LibNotFound,
{name});
}
// This function is called on startup. We need this for LTO since
// LTO calls LLVM functions to compile bitcode files to native code.
// Technically this can be delayed until we read bitcode files, but
// we don't bother to do lazily because the initialization is fast.
static void initLLVM() {
InitializeAllTargets();
InitializeAllTargetMCs();
InitializeAllAsmPrinters();
InitializeAllAsmParsers();
}
// Some command line options or some combinations of them are not allowed.
// This function checks for such errors.
static void checkOptions(Ctx &ctx) {
// The MIPS ABI as of 2016 does not support the GNU-style symbol lookup
// table which is a relatively new feature.
if (ctx.arg.emachine == EM_MIPS && ctx.arg.gnuHash)
ErrAlways(ctx)
<< "the .gnu.hash section is not compatible with the MIPS target";
if (ctx.arg.emachine == EM_ARM) {
if (!ctx.arg.cmseImplib) {
if (!ctx.arg.cmseInputLib.empty())
ErrAlways(ctx) << "--in-implib may not be used without --cmse-implib";
if (!ctx.arg.cmseOutputLib.empty())
ErrAlways(ctx) << "--out-implib may not be used without --cmse-implib";
}
} else {
if (ctx.arg.cmseImplib)
ErrAlways(ctx) << "--cmse-implib is only supported on ARM targets";
if (!ctx.arg.cmseInputLib.empty())
ErrAlways(ctx) << "--in-implib is only supported on ARM targets";
if (!ctx.arg.cmseOutputLib.empty())
ErrAlways(ctx) << "--out-implib is only supported on ARM targets";
}
if (ctx.arg.fixCortexA53Errata843419 && ctx.arg.emachine != EM_AARCH64)
ErrAlways(ctx)
<< "--fix-cortex-a53-843419 is only supported on AArch64 targets";
if (ctx.arg.fixCortexA8 && ctx.arg.emachine != EM_ARM)
ErrAlways(ctx) << "--fix-cortex-a8 is only supported on ARM targets";
if (ctx.arg.armBe8 && ctx.arg.emachine != EM_ARM)
ErrAlways(ctx) << "--be8 is only supported on ARM targets";
if (ctx.arg.fixCortexA8 && !ctx.arg.isLE)
ErrAlways(ctx) << "--fix-cortex-a8 is not supported on big endian targets";
if (ctx.arg.tocOptimize && ctx.arg.emachine != EM_PPC64)
ErrAlways(ctx) << "--toc-optimize is only supported on PowerPC64 targets";
if (ctx.arg.pcRelOptimize && ctx.arg.emachine != EM_PPC64)
ErrAlways(ctx) << "--pcrel-optimize is only supported on PowerPC64 targets";
if (ctx.arg.relaxGP && ctx.arg.emachine != EM_RISCV)
ErrAlways(ctx) << "--relax-gp is only supported on RISC-V targets";
if (ctx.arg.pie && ctx.arg.shared)
ErrAlways(ctx) << "-shared and -pie may not be used together";
if (!ctx.arg.shared && !ctx.arg.filterList.empty())
ErrAlways(ctx) << "-F may not be used without -shared";
if (!ctx.arg.shared && !ctx.arg.auxiliaryList.empty())
ErrAlways(ctx) << "-f may not be used without -shared";
if (ctx.arg.strip == StripPolicy::All && ctx.arg.emitRelocs)
ErrAlways(ctx) << "--strip-all and --emit-relocs may not be used together";
if (ctx.arg.zText && ctx.arg.zIfuncNoplt)
ErrAlways(ctx) << "-z text and -z ifunc-noplt may not be used together";
if (ctx.arg.relocatable) {
if (ctx.arg.shared)
ErrAlways(ctx) << "-r and -shared may not be used together";
if (ctx.arg.gdbIndex)
ErrAlways(ctx) << "-r and --gdb-index may not be used together";
if (ctx.arg.icf != ICFLevel::None)
ErrAlways(ctx) << "-r and --icf may not be used together";
if (ctx.arg.pie)
ErrAlways(ctx) << "-r and -pie may not be used together";
if (ctx.arg.exportDynamic)
ErrAlways(ctx) << "-r and --export-dynamic may not be used together";
if (ctx.arg.debugNames)
ErrAlways(ctx) << "-r and --debug-names may not be used together";
if (!ctx.arg.zSectionHeader)
ErrAlways(ctx) << "-r and -z nosectionheader may not be used together";
}
if (ctx.arg.executeOnly) {
if (ctx.arg.emachine != EM_AARCH64)
ErrAlways(ctx) << "--execute-only is only supported on AArch64 targets";
if (ctx.arg.singleRoRx && !ctx.script->hasSectionsCommand)
ErrAlways(ctx)
<< "--execute-only and --no-rosegment cannot be used together";
}
if (ctx.arg.zRetpolineplt && ctx.arg.zForceIbt)
ErrAlways(ctx) << "-z force-ibt may not be used with -z retpolineplt";
if (ctx.arg.emachine != EM_AARCH64) {
if (ctx.arg.zPacPlt)
ErrAlways(ctx) << "-z pac-plt only supported on AArch64";
if (ctx.arg.zForceBti)
ErrAlways(ctx) << "-z force-bti only supported on AArch64";
if (ctx.arg.zBtiReport != "none")
ErrAlways(ctx) << "-z bti-report only supported on AArch64";
if (ctx.arg.zPauthReport != "none")
ErrAlways(ctx) << "-z pauth-report only supported on AArch64";
if (ctx.arg.zGcsReport != "none")
ErrAlways(ctx) << "-z gcs-report only supported on AArch64";
if (ctx.arg.zGcs != GcsPolicy::Implicit)
ErrAlways(ctx) << "-z gcs only supported on AArch64";
}
if (ctx.arg.emachine != EM_386 && ctx.arg.emachine != EM_X86_64 &&
ctx.arg.zCetReport != "none")
ErrAlways(ctx) << "-z cet-report only supported on X86 and X86_64";
}
static const char *getReproduceOption(opt::InputArgList &args) {
if (auto *arg = args.getLastArg(OPT_reproduce))
return arg->getValue();
return getenv("LLD_REPRODUCE");
}
static bool hasZOption(opt::InputArgList &args, StringRef key) {
bool ret = false;
for (auto *arg : args.filtered(OPT_z))
if (key == arg->getValue()) {
ret = true;
arg->claim();
}
return ret;
}
static bool getZFlag(opt::InputArgList &args, StringRef k1, StringRef k2,
bool defaultValue) {
for (auto *arg : args.filtered(OPT_z)) {
StringRef v = arg->getValue();
if (k1 == v)
defaultValue = true;
else if (k2 == v)
defaultValue = false;
else
continue;
arg->claim();
}
return defaultValue;
}
static SeparateSegmentKind getZSeparate(opt::InputArgList &args) {
auto ret = SeparateSegmentKind::None;
for (auto *arg : args.filtered(OPT_z)) {
StringRef v = arg->getValue();
if (v == "noseparate-code")
ret = SeparateSegmentKind::None;
else if (v == "separate-code")
ret = SeparateSegmentKind::Code;
else if (v == "separate-loadable-segments")
ret = SeparateSegmentKind::Loadable;
else
continue;
arg->claim();
}
return ret;
}
static GnuStackKind getZGnuStack(opt::InputArgList &args) {
auto ret = GnuStackKind::NoExec;
for (auto *arg : args.filtered(OPT_z)) {
StringRef v = arg->getValue();
if (v == "execstack")
ret = GnuStackKind::Exec;
else if (v == "noexecstack")
ret = GnuStackKind::NoExec;
else if (v == "nognustack")
ret = GnuStackKind::None;
else
continue;
arg->claim();
}
return ret;
}
static uint8_t getZStartStopVisibility(Ctx &ctx, opt::InputArgList &args) {
uint8_t ret = STV_PROTECTED;
for (auto *arg : args.filtered(OPT_z)) {
std::pair<StringRef, StringRef> kv = StringRef(arg->getValue()).split('=');
if (kv.first == "start-stop-visibility") {
arg->claim();
if (kv.second == "default")
ret = STV_DEFAULT;
else if (kv.second == "internal")
ret = STV_INTERNAL;
else if (kv.second == "hidden")
ret = STV_HIDDEN;
else if (kv.second == "protected")
ret = STV_PROTECTED;
else
ErrAlways(ctx) << "unknown -z start-stop-visibility= value: "
<< StringRef(kv.second);
}
}
return ret;
}
static GcsPolicy getZGcs(Ctx &ctx, opt::InputArgList &args) {
GcsPolicy ret = GcsPolicy::Implicit;
for (auto *arg : args.filtered(OPT_z)) {
std::pair<StringRef, StringRef> kv = StringRef(arg->getValue()).split('=');
if (kv.first == "gcs") {
arg->claim();
if (kv.second == "implicit")
ret = GcsPolicy::Implicit;
else if (kv.second == "never")
ret = GcsPolicy::Never;
else if (kv.second == "always")
ret = GcsPolicy::Always;
else
ErrAlways(ctx) << "unknown -z gcs= value: " << kv.second;
}
}
return ret;
}
// Report a warning for an unknown -z option.
static void checkZOptions(Ctx &ctx, opt::InputArgList &args) {
// This function is called before getTarget(), when certain options are not
// initialized yet. Claim them here.
args::getZOptionValue(args, OPT_z, "max-page-size", 0);
args::getZOptionValue(args, OPT_z, "common-page-size", 0);
getZFlag(args, "rel", "rela", false);
for (auto *arg : args.filtered(OPT_z))
if (!arg->isClaimed())
Warn(ctx) << "unknown -z value: " << StringRef(arg->getValue());
}
constexpr const char *saveTempsValues[] = {
"resolution", "preopt", "promote", "internalize", "import",
"opt", "precodegen", "prelink", "combinedindex"};
LinkerDriver::LinkerDriver(Ctx &ctx) : ctx(ctx) {}
void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
ELFOptTable parser;
opt::InputArgList args = parser.parse(ctx, argsArr.slice(1));
// Interpret these flags early because Err/Warn depend on them.
ctx.e.errorLimit = args::getInteger(args, OPT_error_limit, 20);
ctx.e.fatalWarnings =
args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false) &&
!args.hasArg(OPT_no_warnings);
ctx.e.suppressWarnings = args.hasArg(OPT_no_warnings);
// Handle -help
if (args.hasArg(OPT_help)) {
printHelp(ctx);
return;
}
// Handle -v or -version.
//
// A note about "compatible with GNU linkers" message: this is a hack for
// scripts generated by GNU Libtool up to 2021-10 to recognize LLD as
// a GNU compatible linker. See
// <https://lists.gnu.org/archive/html/libtool/2017-01/msg00007.html>.
//
// This is somewhat ugly hack, but in reality, we had no choice other
// than doing this. Considering the very long release cycle of Libtool,
// it is not easy to improve it to recognize LLD as a GNU compatible
// linker in a timely manner. Even if we can make it, there are still a
// lot of "configure" scripts out there that are generated by old version
// of Libtool. We cannot convince every software developer to migrate to
// the latest version and re-generate scripts. So we have this hack.
if (args.hasArg(OPT_v) || args.hasArg(OPT_version))
Msg(ctx) << getLLDVersion() << " (compatible with GNU linkers)";
if (const char *path = getReproduceOption(args)) {
// Note that --reproduce is a debug option so you can ignore it
// if you are trying to understand the whole picture of the code.
Expected<std::unique_ptr<TarWriter>> errOrWriter =
TarWriter::create(path, path::stem(path));
if (errOrWriter) {
ctx.tar = std::move(*errOrWriter);
ctx.tar->append("response.txt", createResponseFile(args));
ctx.tar->append("version.txt", getLLDVersion() + "\n");
StringRef ltoSampleProfile = args.getLastArgValue(OPT_lto_sample_profile);
if (!ltoSampleProfile.empty())
readFile(ctx, ltoSampleProfile);
} else {
ErrAlways(ctx) << "--reproduce: " << errOrWriter.takeError();
}
}
readConfigs(ctx, args);
checkZOptions(ctx, args);
// The behavior of -v or --version is a bit strange, but this is
// needed for compatibility with GNU linkers.
if (args.hasArg(OPT_v) && !args.hasArg(OPT_INPUT))
return;
if (args.hasArg(OPT_version))
return;
// Initialize time trace profiler.
if (ctx.arg.timeTraceEnabled)
timeTraceProfilerInitialize(ctx.arg.timeTraceGranularity, ctx.arg.progName);
{
llvm::TimeTraceScope timeScope("ExecuteLinker");
initLLVM();
createFiles(args);
if (errCount(ctx))
return;
inferMachineType();
setConfigs(ctx, args);
checkOptions(ctx);
if (errCount(ctx))
return;
invokeELFT(link, args);
}
if (ctx.arg.timeTraceEnabled) {
checkError(ctx.e, timeTraceProfilerWrite(
args.getLastArgValue(OPT_time_trace_eq).str(),
ctx.arg.outputFile));
timeTraceProfilerCleanup();
}
}
static std::string getRpath(opt::InputArgList &args) {
SmallVector<StringRef, 0> v = args::getStrings(args, OPT_rpath);
return llvm::join(v.begin(), v.end(), ":");
}
// Determines what we should do if there are remaining unresolved
// symbols after the name resolution.
static void setUnresolvedSymbolPolicy(Ctx &ctx, opt::InputArgList &args) {
UnresolvedPolicy errorOrWarn = args.hasFlag(OPT_error_unresolved_symbols,
OPT_warn_unresolved_symbols, true)
? UnresolvedPolicy::ReportError
: UnresolvedPolicy::Warn;
// -shared implies --unresolved-symbols=ignore-all because missing
// symbols are likely to be resolved at runtime.
bool diagRegular = !ctx.arg.shared, diagShlib = !ctx.arg.shared;
for (const opt::Arg *arg : args) {
switch (arg->getOption().getID()) {
case OPT_unresolved_symbols: {
StringRef s = arg->getValue();
if (s == "ignore-all") {
diagRegular = false;
diagShlib = false;
} else if (s == "ignore-in-object-files") {
diagRegular = false;
diagShlib = true;
} else if (s == "ignore-in-shared-libs") {
diagRegular = true;
diagShlib = false;
} else if (s == "report-all") {
diagRegular = true;
diagShlib = true;
} else {
ErrAlways(ctx) << "unknown --unresolved-symbols value: " << s;
}
break;
}
case OPT_no_undefined:
diagRegular = true;
break;
case OPT_z:
if (StringRef(arg->getValue()) == "defs")
diagRegular = true;
else if (StringRef(arg->getValue()) == "undefs")
diagRegular = false;
else
break;
arg->claim();
break;
case OPT_allow_shlib_undefined:
diagShlib = false;
break;
case OPT_no_allow_shlib_undefined:
diagShlib = true;
break;
}
}
ctx.arg.unresolvedSymbols =
diagRegular ? errorOrWarn : UnresolvedPolicy::Ignore;
ctx.arg.unresolvedSymbolsInShlib =
diagShlib ? errorOrWarn : UnresolvedPolicy::Ignore;
}
static Target2Policy getTarget2(Ctx &ctx, opt::InputArgList &args) {
StringRef s = args.getLastArgValue(OPT_target2, "got-rel");
if (s == "rel")
return Target2Policy::Rel;
if (s == "abs")
return Target2Policy::Abs;
if (s == "got-rel")
return Target2Policy::GotRel;
ErrAlways(ctx) << "unknown --target2 option: " << s;
return Target2Policy::GotRel;
}
static bool isOutputFormatBinary(Ctx &ctx, opt::InputArgList &args) {
StringRef s = args.getLastArgValue(OPT_oformat, "elf");
if (s == "binary")
return true;
if (!s.starts_with("elf"))
ErrAlways(ctx) << "unknown --oformat value: " << s;
return false;
}
static DiscardPolicy getDiscard(opt::InputArgList &args) {
auto *arg =
args.getLastArg(OPT_discard_all, OPT_discard_locals, OPT_discard_none);
if (!arg)
return DiscardPolicy::Default;
if (arg->getOption().getID() == OPT_discard_all)
return DiscardPolicy::All;
if (arg->getOption().getID() == OPT_discard_locals)
return DiscardPolicy::Locals;
return DiscardPolicy::None;
}
static StringRef getDynamicLinker(Ctx &ctx, opt::InputArgList &args) {
auto *arg = args.getLastArg(OPT_dynamic_linker, OPT_no_dynamic_linker);
if (!arg)
return "";
if (arg->getOption().getID() == OPT_no_dynamic_linker) {
// --no-dynamic-linker suppresses undefined weak symbols in .dynsym
ctx.arg.noDynamicLinker = true;
return "";
}
return arg->getValue();
}
static int getMemtagMode(Ctx &ctx, opt::InputArgList &args) {
StringRef memtagModeArg = args.getLastArgValue(OPT_android_memtag_mode);
if (memtagModeArg.empty()) {
if (ctx.arg.androidMemtagStack)
Warn(ctx) << "--android-memtag-mode is unspecified, leaving "
"--android-memtag-stack a no-op";
else if (ctx.arg.androidMemtagHeap)
Warn(ctx) << "--android-memtag-mode is unspecified, leaving "
"--android-memtag-heap a no-op";
return ELF::NT_MEMTAG_LEVEL_NONE;
}
if (memtagModeArg == "sync")
return ELF::NT_MEMTAG_LEVEL_SYNC;
if (memtagModeArg == "async")
return ELF::NT_MEMTAG_LEVEL_ASYNC;
if (memtagModeArg == "none")
return ELF::NT_MEMTAG_LEVEL_NONE;
ErrAlways(ctx) << "unknown --android-memtag-mode value: \"" << memtagModeArg
<< "\", should be one of {async, sync, none}";
return ELF::NT_MEMTAG_LEVEL_NONE;
}
static ICFLevel getICF(opt::InputArgList &args) {
auto *arg = args.getLastArg(OPT_icf_none, OPT_icf_safe, OPT_icf_all);
if (!arg || arg->getOption().getID() == OPT_icf_none)
return ICFLevel::None;
if (arg->getOption().getID() == OPT_icf_safe)
return ICFLevel::Safe;
return ICFLevel::All;
}
static StripPolicy getStrip(Ctx &ctx, opt::InputArgList &args) {
if (args.hasArg(OPT_relocatable))
return StripPolicy::None;
if (!ctx.arg.zSectionHeader)
return StripPolicy::All;
auto *arg = args.getLastArg(OPT_strip_all, OPT_strip_debug);
if (!arg)
return StripPolicy::None;
if (arg->getOption().getID() == OPT_strip_all)
return StripPolicy::All;
return StripPolicy::Debug;
}
static uint64_t parseSectionAddress(Ctx &ctx, StringRef s,
opt::InputArgList &args,
const opt::Arg &arg) {
uint64_t va = 0;
s.consume_front("0x");
if (!to_integer(s, va, 16))
ErrAlways(ctx) << "invalid argument: " << arg.getAsString(args);
return va;
}
static StringMap<uint64_t> getSectionStartMap(Ctx &ctx,
opt::InputArgList &args) {
StringMap<uint64_t> ret;
for (auto *arg : args.filtered(OPT_section_start)) {
StringRef name;
StringRef addr;
std::tie(name, addr) = StringRef(arg->getValue()).split('=');
ret[name] = parseSectionAddress(ctx, addr, args, *arg);
}
if (auto *arg = args.getLastArg(OPT_Ttext))
ret[".text"] = parseSectionAddress(ctx, arg->getValue(), args, *arg);
if (auto *arg = args.getLastArg(OPT_Tdata))
ret[".data"] = parseSectionAddress(ctx, arg->getValue(), args, *arg);
if (auto *arg = args.getLastArg(OPT_Tbss))
ret[".bss"] = parseSectionAddress(ctx, arg->getValue(), args, *arg);
return ret;
}
static SortSectionPolicy getSortSection(Ctx &ctx, opt::InputArgList &args) {
StringRef s = args.getLastArgValue(OPT_sort_section);
if (s == "alignment")
return SortSectionPolicy::Alignment;
if (s == "name")
return SortSectionPolicy::Name;
if (!s.empty())
ErrAlways(ctx) << "unknown --sort-section rule: " << s;
return SortSectionPolicy::Default;
}
static OrphanHandlingPolicy getOrphanHandling(Ctx &ctx,
opt::InputArgList &args) {
StringRef s = args.getLastArgValue(OPT_orphan_handling, "place");
if (s == "warn")
return OrphanHandlingPolicy::Warn;
if (s == "error")
return OrphanHandlingPolicy::Error;
if (s != "place")
ErrAlways(ctx) << "unknown --orphan-handling mode: " << s;
return OrphanHandlingPolicy::Place;
}
// Parse --build-id or --build-id=<style>. We handle "tree" as a
// synonym for "sha1" because all our hash functions including
// --build-id=sha1 are actually tree hashes for performance reasons.
static std::pair<BuildIdKind, SmallVector<uint8_t, 0>>
getBuildId(Ctx &ctx, opt::InputArgList &args) {
auto *arg = args.getLastArg(OPT_build_id);
if (!arg)
return {BuildIdKind::None, {}};
StringRef s = arg->getValue();
if (s == "fast")
return {BuildIdKind::Fast, {}};
if (s == "md5")
return {BuildIdKind::Md5, {}};
if (s == "sha1" || s == "tree")
return {BuildIdKind::Sha1, {}};
if (s == "uuid")
return {BuildIdKind::Uuid, {}};
if (s.starts_with("0x"))
return {BuildIdKind::Hexstring, parseHex(s.substr(2))};
if (s != "none")
ErrAlways(ctx) << "unknown --build-id style: " << s;
return {BuildIdKind::None, {}};
}
static std::pair<bool, bool> getPackDynRelocs(Ctx &ctx,
opt::InputArgList &args) {
StringRef s = args.getLastArgValue(OPT_pack_dyn_relocs, "none");
if (s == "android")
return {true, false};
if (s == "relr")
return {false, true};
if (s == "android+relr")
return {true, true};
if (s != "none")
ErrAlways(ctx) << "unknown --pack-dyn-relocs format: " << s;
return {false, false};
}
static void readCallGraph(Ctx &ctx, MemoryBufferRef mb) {
// Build a map from symbol name to section
DenseMap<StringRef, Symbol *> map;
for (ELFFileBase *file : ctx.objectFiles)
for (Symbol *sym : file->getSymbols())
map[sym->getName()] = sym;
auto findSection = [&](StringRef name) -> InputSectionBase * {
Symbol *sym = map.lookup(name);
if (!sym) {
if (ctx.arg.warnSymbolOrdering)
Warn(ctx) << mb.getBufferIdentifier() << ": no such symbol: " << name;
return nullptr;
}
maybeWarnUnorderableSymbol(ctx, sym);
if (Defined *dr = dyn_cast_or_null<Defined>(sym))
return dyn_cast_or_null<InputSectionBase>(dr->section);
return nullptr;
};
for (StringRef line : args::getLines(mb)) {
SmallVector<StringRef, 3> fields;
line.split(fields, ' ');
uint64_t count;
if (fields.size() != 3 || !to_integer(fields[2], count)) {
ErrAlways(ctx) << mb.getBufferIdentifier() << ": parse error";
return;
}
if (InputSectionBase *from = findSection(fields[0]))
if (InputSectionBase *to = findSection(fields[1]))
ctx.arg.callGraphProfile[std::make_pair(from, to)] += count;
}
}
// If SHT_LLVM_CALL_GRAPH_PROFILE and its relocation section exist, returns
// true and populates cgProfile and symbolIndices.
template <class ELFT>
static bool
processCallGraphRelocations(Ctx &ctx, SmallVector<uint32_t, 32> &symbolIndices,
ArrayRef<typename ELFT::CGProfile> &cgProfile,
ObjFile<ELFT> *inputObj) {
if (inputObj->cgProfileSectionIndex == SHN_UNDEF)
return false;
ArrayRef<Elf_Shdr_Impl<ELFT>> objSections =
inputObj->template getELFShdrs<ELFT>();
symbolIndices.clear();
const ELFFile<ELFT> &obj = inputObj->getObj();
cgProfile =
check(obj.template getSectionContentsAsArray<typename ELFT::CGProfile>(
objSections[inputObj->cgProfileSectionIndex]));
for (size_t i = 0, e = objSections.size(); i < e; ++i) {
const Elf_Shdr_Impl<ELFT> &sec = objSections[i];
if (sec.sh_info == inputObj->cgProfileSectionIndex) {
if (sec.sh_type == SHT_CREL) {
auto crels =
CHECK(obj.crels(sec), "could not retrieve cg profile rela section");
for (const auto &rel : crels.first)
symbolIndices.push_back(rel.getSymbol(false));
for (const auto &rel : crels.second)
symbolIndices.push_back(rel.getSymbol(false));
break;
}
if (sec.sh_type == SHT_RELA) {
ArrayRef<typename ELFT::Rela> relas =
CHECK(obj.relas(sec), "could not retrieve cg profile rela section");
for (const typename ELFT::Rela &rel : relas)
symbolIndices.push_back(rel.getSymbol(ctx.arg.isMips64EL));
break;
}
if (sec.sh_type == SHT_REL) {
ArrayRef<typename ELFT::Rel> rels =