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diff --git a/contrib/llvm-project/lld/ELF/InputFiles.cpp b/contrib/llvm-project/lld/ELF/InputFiles.cpp
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+++ b/contrib/llvm-project/lld/ELF/InputFiles.cpp
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+//===- InputFiles.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 "InputFiles.h"
+#include "Driver.h"
+#include "InputSection.h"
+#include "LinkerScript.h"
+#include "SymbolTable.h"
+#include "Symbols.h"
+#include "SyntheticSections.h"
+#include "lld/Common/ErrorHandler.h"
+#include "lld/Common/Memory.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/Analysis.h"
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/LTO/LTO.h"
+#include "llvm/MC/StringTableBuilder.h"
+#include "llvm/Object/ELFObjectFile.h"
+#include "llvm/Support/ARMAttributeParser.h"
+#include "llvm/Support/ARMBuildAttributes.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/TarWriter.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+using namespace llvm::ELF;
+using namespace llvm::object;
+using namespace llvm::sys;
+using namespace llvm::sys::fs;
+using namespace llvm::support::endian;
+
+using namespace lld;
+using namespace lld::elf;
+
+bool InputFile::isInGroup;
+uint32_t InputFile::nextGroupId;
+std::vector<BinaryFile *> elf::binaryFiles;
+std::vector<BitcodeFile *> elf::bitcodeFiles;
+std::vector<LazyObjFile *> elf::lazyObjFiles;
+std::vector<InputFile *> elf::objectFiles;
+std::vector<SharedFile *> elf::sharedFiles;
+
+std::unique_ptr<TarWriter> elf::tar;
+
+static ELFKind getELFKind(MemoryBufferRef mb, StringRef archiveName) {
+ unsigned char size;
+ unsigned char endian;
+ std::tie(size, endian) = getElfArchType(mb.getBuffer());
+
+ auto report = [&](StringRef msg) {
+ StringRef filename = mb.getBufferIdentifier();
+ if (archiveName.empty())
+ fatal(filename + ": " + msg);
+ else
+ fatal(archiveName + "(" + filename + "): " + msg);
+ };
+
+ if (!mb.getBuffer().startswith(ElfMagic))
+ report("not an ELF file");
+ if (endian != ELFDATA2LSB && endian != ELFDATA2MSB)
+ report("corrupted ELF file: invalid data encoding");
+ if (size != ELFCLASS32 && size != ELFCLASS64)
+ report("corrupted ELF file: invalid file class");
+
+ size_t bufSize = mb.getBuffer().size();
+ if ((size == ELFCLASS32 && bufSize < sizeof(Elf32_Ehdr)) ||
+ (size == ELFCLASS64 && bufSize < sizeof(Elf64_Ehdr)))
+ report("corrupted ELF file: file is too short");
+
+ if (size == ELFCLASS32)
+ return (endian == ELFDATA2LSB) ? ELF32LEKind : ELF32BEKind;
+ return (endian == ELFDATA2LSB) ? ELF64LEKind : ELF64BEKind;
+}
+
+InputFile::InputFile(Kind k, MemoryBufferRef m)
+ : mb(m), groupId(nextGroupId), fileKind(k) {
+ // All files within the same --{start,end}-group get the same group ID.
+ // Otherwise, a new file will get a new group ID.
+ if (!isInGroup)
+ ++nextGroupId;
+}
+
+Optional<MemoryBufferRef> elf::readFile(StringRef path) {
+ // The --chroot option changes our virtual root directory.
+ // This is useful when you are dealing with files created by --reproduce.
+ if (!config->chroot.empty() && path.startswith("/"))
+ path = saver.save(config->chroot + path);
+
+ log(path);
+
+ auto mbOrErr = MemoryBuffer::getFile(path, -1, false);
+ if (auto ec = mbOrErr.getError()) {
+ error("cannot open " + path + ": " + ec.message());
+ return None;
+ }
+
+ std::unique_ptr<MemoryBuffer> &mb = *mbOrErr;
+ MemoryBufferRef mbref = mb->getMemBufferRef();
+ make<std::unique_ptr<MemoryBuffer>>(std::move(mb)); // take MB ownership
+
+ if (tar)
+ tar->append(relativeToRoot(path), mbref.getBuffer());
+ return mbref;
+}
+
+// All input object files must be for the same architecture
+// (e.g. it does not make sense to link x86 object files with
+// MIPS object files.) This function checks for that error.
+static bool isCompatible(InputFile *file) {
+ if (!file->isElf() && !isa<BitcodeFile>(file))
+ return true;
+
+ if (file->ekind == config->ekind && file->emachine == config->emachine) {
+ if (config->emachine != EM_MIPS)
+ return true;
+ if (isMipsN32Abi(file) == config->mipsN32Abi)
+ return true;
+ }
+
+ if (!config->emulation.empty()) {
+ error(toString(file) + " is incompatible with " + config->emulation);
+ } else {
+ InputFile *existing;
+ if (!objectFiles.empty())
+ existing = objectFiles[0];
+ else if (!sharedFiles.empty())
+ existing = sharedFiles[0];
+ else
+ existing = bitcodeFiles[0];
+
+ error(toString(file) + " is incompatible with " + toString(existing));
+ }
+
+ return false;
+}
+
+template <class ELFT> static void doParseFile(InputFile *file) {
+ if (!isCompatible(file))
+ return;
+
+ // Binary file
+ if (auto *f = dyn_cast<BinaryFile>(file)) {
+ binaryFiles.push_back(f);
+ f->parse();
+ return;
+ }
+
+ // .a file
+ if (auto *f = dyn_cast<ArchiveFile>(file)) {
+ f->parse();
+ return;
+ }
+
+ // Lazy object file
+ if (auto *f = dyn_cast<LazyObjFile>(file)) {
+ lazyObjFiles.push_back(f);
+ f->parse<ELFT>();
+ return;
+ }
+
+ if (config->trace)
+ message(toString(file));
+
+ // .so file
+ if (auto *f = dyn_cast<SharedFile>(file)) {
+ f->parse<ELFT>();
+ return;
+ }
+
+ // LLVM bitcode file
+ if (auto *f = dyn_cast<BitcodeFile>(file)) {
+ bitcodeFiles.push_back(f);
+ f->parse<ELFT>();
+ return;
+ }
+
+ // Regular object file
+ objectFiles.push_back(file);
+ cast<ObjFile<ELFT>>(file)->parse();
+}
+
+// Add symbols in File to the symbol table.
+void elf::parseFile(InputFile *file) {
+ switch (config->ekind) {
+ case ELF32LEKind:
+ doParseFile<ELF32LE>(file);
+ return;
+ case ELF32BEKind:
+ doParseFile<ELF32BE>(file);
+ return;
+ case ELF64LEKind:
+ doParseFile<ELF64LE>(file);
+ return;
+ case ELF64BEKind:
+ doParseFile<ELF64BE>(file);
+ return;
+ default:
+ llvm_unreachable("unknown ELFT");
+ }
+}
+
+// Concatenates arguments to construct a string representing an error location.
+static std::string createFileLineMsg(StringRef path, unsigned line) {
+ std::string filename = path::filename(path);
+ std::string lineno = ":" + std::to_string(line);
+ if (filename == path)
+ return filename + lineno;
+ return filename + lineno + " (" + path.str() + lineno + ")";
+}
+
+template <class ELFT>
+static std::string getSrcMsgAux(ObjFile<ELFT> &file, const Symbol &sym,
+ InputSectionBase &sec, uint64_t offset) {
+ // In DWARF, functions and variables are stored to different places.
+ // First, lookup a function for a given offset.
+ if (Optional<DILineInfo> info = file.getDILineInfo(&sec, offset))
+ return createFileLineMsg(info->FileName, info->Line);
+
+ // If it failed, lookup again as a variable.
+ if (Optional<std::pair<std::string, unsigned>> fileLine =
+ file.getVariableLoc(sym.getName()))
+ return createFileLineMsg(fileLine->first, fileLine->second);
+
+ // File.sourceFile contains STT_FILE symbol, and that is a last resort.
+ return file.sourceFile;
+}
+
+std::string InputFile::getSrcMsg(const Symbol &sym, InputSectionBase &sec,
+ uint64_t offset) {
+ if (kind() != ObjKind)
+ return "";
+ switch (config->ekind) {
+ default:
+ llvm_unreachable("Invalid kind");
+ case ELF32LEKind:
+ return getSrcMsgAux(cast<ObjFile<ELF32LE>>(*this), sym, sec, offset);
+ case ELF32BEKind:
+ return getSrcMsgAux(cast<ObjFile<ELF32BE>>(*this), sym, sec, offset);
+ case ELF64LEKind:
+ return getSrcMsgAux(cast<ObjFile<ELF64LE>>(*this), sym, sec, offset);
+ case ELF64BEKind:
+ return getSrcMsgAux(cast<ObjFile<ELF64BE>>(*this), sym, sec, offset);
+ }
+}
+
+template <class ELFT> void ObjFile<ELFT>::initializeDwarf() {
+ dwarf = llvm::make_unique<DWARFContext>(make_unique<LLDDwarfObj<ELFT>>(this));
+ for (std::unique_ptr<DWARFUnit> &cu : dwarf->compile_units()) {
+ auto report = [](Error err) {
+ handleAllErrors(std::move(err),
+ [](ErrorInfoBase &info) { warn(info.message()); });
+ };
+ Expected<const DWARFDebugLine::LineTable *> expectedLT =
+ dwarf->getLineTableForUnit(cu.get(), report);
+ const DWARFDebugLine::LineTable *lt = nullptr;
+ if (expectedLT)
+ lt = *expectedLT;
+ else
+ report(expectedLT.takeError());
+ if (!lt)
+ continue;
+ lineTables.push_back(lt);
+
+ // Loop over variable records and insert them to variableLoc.
+ for (const auto &entry : cu->dies()) {
+ DWARFDie die(cu.get(), &entry);
+ // Skip all tags that are not variables.
+ if (die.getTag() != dwarf::DW_TAG_variable)
+ continue;
+
+ // Skip if a local variable because we don't need them for generating
+ // error messages. In general, only non-local symbols can fail to be
+ // linked.
+ if (!dwarf::toUnsigned(die.find(dwarf::DW_AT_external), 0))
+ continue;
+
+ // Get the source filename index for the variable.
+ unsigned file = dwarf::toUnsigned(die.find(dwarf::DW_AT_decl_file), 0);
+ if (!lt->hasFileAtIndex(file))
+ continue;
+
+ // Get the line number on which the variable is declared.
+ unsigned line = dwarf::toUnsigned(die.find(dwarf::DW_AT_decl_line), 0);
+
+ // Here we want to take the variable name to add it into variableLoc.
+ // Variable can have regular and linkage name associated. At first, we try
+ // to get linkage name as it can be different, for example when we have
+ // two variables in different namespaces of the same object. Use common
+ // name otherwise, but handle the case when it also absent in case if the
+ // input object file lacks some debug info.
+ StringRef name =
+ dwarf::toString(die.find(dwarf::DW_AT_linkage_name),
+ dwarf::toString(die.find(dwarf::DW_AT_name), ""));
+ if (!name.empty())
+ variableLoc.insert({name, {lt, file, line}});
+ }
+ }
+}
+
+// Returns the pair of file name and line number describing location of data
+// object (variable, array, etc) definition.
+template <class ELFT>
+Optional<std::pair<std::string, unsigned>>
+ObjFile<ELFT>::getVariableLoc(StringRef name) {
+ llvm::call_once(initDwarfLine, [this]() { initializeDwarf(); });
+
+ // Return if we have no debug information about data object.
+ auto it = variableLoc.find(name);
+ if (it == variableLoc.end())
+ return None;
+
+ // Take file name string from line table.
+ std::string fileName;
+ if (!it->second.lt->getFileNameByIndex(
+ it->second.file, {},
+ DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, fileName))
+ return None;
+
+ return std::make_pair(fileName, it->second.line);
+}
+
+// Returns source line information for a given offset
+// using DWARF debug info.
+template <class ELFT>
+Optional<DILineInfo> ObjFile<ELFT>::getDILineInfo(InputSectionBase *s,
+ uint64_t offset) {
+ llvm::call_once(initDwarfLine, [this]() { initializeDwarf(); });
+
+ // Detect SectionIndex for specified section.
+ uint64_t sectionIndex = object::SectionedAddress::UndefSection;
+ ArrayRef<InputSectionBase *> sections = s->file->getSections();
+ for (uint64_t curIndex = 0; curIndex < sections.size(); ++curIndex) {
+ if (s == sections[curIndex]) {
+ sectionIndex = curIndex;
+ break;
+ }
+ }
+
+ // Use fake address calcuated by adding section file offset and offset in
+ // section. See comments for ObjectInfo class.
+ DILineInfo info;
+ for (const llvm::DWARFDebugLine::LineTable *lt : lineTables) {
+ if (lt->getFileLineInfoForAddress(
+ {s->getOffsetInFile() + offset, sectionIndex}, nullptr,
+ DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, info))
+ return info;
+ }
+ return None;
+}
+
+// Returns "<internal>", "foo.a(bar.o)" or "baz.o".
+std::string lld::toString(const InputFile *f) {
+ if (!f)
+ return "<internal>";
+
+ if (f->toStringCache.empty()) {
+ if (f->archiveName.empty())
+ f->toStringCache = f->getName();
+ else
+ f->toStringCache = (f->archiveName + "(" + f->getName() + ")").str();
+ }
+ return f->toStringCache;
+}
+
+ELFFileBase::ELFFileBase(Kind k, MemoryBufferRef mb) : InputFile(k, mb) {
+ ekind = getELFKind(mb, "");
+
+ switch (ekind) {
+ case ELF32LEKind:
+ init<ELF32LE>();
+ break;
+ case ELF32BEKind:
+ init<ELF32BE>();
+ break;
+ case ELF64LEKind:
+ init<ELF64LE>();
+ break;
+ case ELF64BEKind:
+ init<ELF64BE>();
+ break;
+ default:
+ llvm_unreachable("getELFKind");
+ }
+}
+
+template <typename Elf_Shdr>
+static const Elf_Shdr *findSection(ArrayRef<Elf_Shdr> sections, uint32_t type) {
+ for (const Elf_Shdr &sec : sections)
+ if (sec.sh_type == type)
+ return &sec;
+ return nullptr;
+}
+
+template <class ELFT> void ELFFileBase::init() {
+ using Elf_Shdr = typename ELFT::Shdr;
+ using Elf_Sym = typename ELFT::Sym;
+
+ // Initialize trivial attributes.
+ const ELFFile<ELFT> &obj = getObj<ELFT>();
+ emachine = obj.getHeader()->e_machine;
+ osabi = obj.getHeader()->e_ident[llvm::ELF::EI_OSABI];
+ abiVersion = obj.getHeader()->e_ident[llvm::ELF::EI_ABIVERSION];
+
+ ArrayRef<Elf_Shdr> sections = CHECK(obj.sections(), this);
+
+ // Find a symbol table.
+ bool isDSO =
+ (identify_magic(mb.getBuffer()) == file_magic::elf_shared_object);
+ const Elf_Shdr *symtabSec =
+ findSection(sections, isDSO ? SHT_DYNSYM : SHT_SYMTAB);
+
+ if (!symtabSec)
+ return;
+
+ // Initialize members corresponding to a symbol table.
+ firstGlobal = symtabSec->sh_info;
+
+ ArrayRef<Elf_Sym> eSyms = CHECK(obj.symbols(symtabSec), this);
+ if (firstGlobal == 0 || firstGlobal > eSyms.size())
+ fatal(toString(this) + ": invalid sh_info in symbol table");
+
+ elfSyms = reinterpret_cast<const void *>(eSyms.data());
+ numELFSyms = eSyms.size();
+ stringTable = CHECK(obj.getStringTableForSymtab(*symtabSec, sections), this);
+}
+
+template <class ELFT>
+uint32_t ObjFile<ELFT>::getSectionIndex(const Elf_Sym &sym) const {
+ return CHECK(
+ this->getObj().getSectionIndex(&sym, getELFSyms<ELFT>(), shndxTable),
+ this);
+}
+
+template <class ELFT> ArrayRef<Symbol *> ObjFile<ELFT>::getLocalSymbols() {
+ if (this->symbols.empty())
+ return {};
+ return makeArrayRef(this->symbols).slice(1, this->firstGlobal - 1);
+}
+
+template <class ELFT> ArrayRef<Symbol *> ObjFile<ELFT>::getGlobalSymbols() {
+ return makeArrayRef(this->symbols).slice(this->firstGlobal);
+}
+
+template <class ELFT> void ObjFile<ELFT>::parse(bool ignoreComdats) {
+ // Read a section table. justSymbols is usually false.
+ if (this->justSymbols)
+ initializeJustSymbols();
+ else
+ initializeSections(ignoreComdats);
+
+ // Read a symbol table.
+ initializeSymbols();
+}
+
+// Sections with SHT_GROUP and comdat bits define comdat section groups.
+// They are identified and deduplicated by group name. This function
+// returns a group name.
+template <class ELFT>
+StringRef ObjFile<ELFT>::getShtGroupSignature(ArrayRef<Elf_Shdr> sections,
+ const Elf_Shdr &sec) {
+ typename ELFT::SymRange symbols = this->getELFSyms<ELFT>();
+ if (sec.sh_info >= symbols.size())
+ fatal(toString(this) + ": invalid symbol index");
+ const typename ELFT::Sym &sym = symbols[sec.sh_info];
+ StringRef signature = CHECK(sym.getName(this->stringTable), this);
+
+ // As a special case, if a symbol is a section symbol and has no name,
+ // we use a section name as a signature.
+ //
+ // Such SHT_GROUP sections are invalid from the perspective of the ELF
+ // standard, but GNU gold 1.14 (the newest version as of July 2017) or
+ // older produce such sections as outputs for the -r option, so we need
+ // a bug-compatibility.
+ if (signature.empty() && sym.getType() == STT_SECTION)
+ return getSectionName(sec);
+ return signature;
+}
+
+template <class ELFT> bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &sec) {
+ // On a regular link we don't merge sections if -O0 (default is -O1). This
+ // sometimes makes the linker significantly faster, although the output will
+ // be bigger.
+ //
+ // Doing the same for -r would create a problem as it would combine sections
+ // with different sh_entsize. One option would be to just copy every SHF_MERGE
+ // section as is to the output. While this would produce a valid ELF file with
+ // usable SHF_MERGE sections, tools like (llvm-)?dwarfdump get confused when
+ // they see two .debug_str. We could have separate logic for combining
+ // SHF_MERGE sections based both on their name and sh_entsize, but that seems
+ // to be more trouble than it is worth. Instead, we just use the regular (-O1)
+ // logic for -r.
+ if (config->optimize == 0 && !config->relocatable)
+ return false;
+
+ // A mergeable section with size 0 is useless because they don't have
+ // any data to merge. A mergeable string section with size 0 can be
+ // argued as invalid because it doesn't end with a null character.
+ // We'll avoid a mess by handling them as if they were non-mergeable.
+ if (sec.sh_size == 0)
+ return false;
+
+ // Check for sh_entsize. The ELF spec is not clear about the zero
+ // sh_entsize. It says that "the member [sh_entsize] contains 0 if
+ // the section does not hold a table of fixed-size entries". We know
+ // that Rust 1.13 produces a string mergeable section with a zero
+ // sh_entsize. Here we just accept it rather than being picky about it.
+ uint64_t entSize = sec.sh_entsize;
+ if (entSize == 0)
+ return false;
+ if (sec.sh_size % entSize)
+ fatal(toString(this) +
+ ": SHF_MERGE section size must be a multiple of sh_entsize");
+
+ uint64_t flags = sec.sh_flags;
+ if (!(flags & SHF_MERGE))
+ return false;
+ if (flags & SHF_WRITE)
+ fatal(toString(this) + ": writable SHF_MERGE section is not supported");
+
+ return true;
+}
+
+// This is for --just-symbols.
+//
+// --just-symbols is a very minor feature that allows you to link your
+// output against other existing program, so that if you load both your
+// program and the other program into memory, your output can refer the
+// other program's symbols.
+//
+// When the option is given, we link "just symbols". The section table is
+// initialized with null pointers.
+template <class ELFT> void ObjFile<ELFT>::initializeJustSymbols() {
+ ArrayRef<Elf_Shdr> sections = CHECK(this->getObj().sections(), this);
+ this->sections.resize(sections.size());
+}
+
+// An ELF object file may contain a `.deplibs` section. If it exists, the
+// section contains a list of library specifiers such as `m` for libm. This
+// function resolves a given name by finding the first matching library checking
+// the various ways that a library can be specified to LLD. This ELF extension
+// is a form of autolinking and is called `dependent libraries`. It is currently
+// unique to LLVM and lld.
+static void addDependentLibrary(StringRef specifier, const InputFile *f) {
+ if (!config->dependentLibraries)
+ return;
+ if (fs::exists(specifier))
+ driver->addFile(specifier, /*withLOption=*/false);
+ else if (Optional<std::string> s = findFromSearchPaths(specifier))
+ driver->addFile(*s, /*withLOption=*/true);
+ else if (Optional<std::string> s = searchLibraryBaseName(specifier))
+ driver->addFile(*s, /*withLOption=*/true);
+ else
+ error(toString(f) +
+ ": unable to find library from dependent library specifier: " +
+ specifier);
+}
+
+template <class ELFT>
+void ObjFile<ELFT>::initializeSections(bool ignoreComdats) {
+ const ELFFile<ELFT> &obj = this->getObj();
+
+ ArrayRef<Elf_Shdr> objSections = CHECK(obj.sections(), this);
+ uint64_t size = objSections.size();
+ this->sections.resize(size);
+ this->sectionStringTable =
+ CHECK(obj.getSectionStringTable(objSections), this);
+
+ for (size_t i = 0, e = objSections.size(); i < e; i++) {
+ if (this->sections[i] == &InputSection::discarded)
+ continue;
+ const Elf_Shdr &sec = objSections[i];
+
+ if (sec.sh_type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
+ cgProfile =
+ check(obj.template getSectionContentsAsArray<Elf_CGProfile>(&sec));
+
+ // SHF_EXCLUDE'ed sections are discarded by the linker. However,
+ // if -r is given, we'll let the final link discard such sections.
+ // This is compatible with GNU.
+ if ((sec.sh_flags & SHF_EXCLUDE) && !config->relocatable) {
+ if (sec.sh_type == SHT_LLVM_ADDRSIG) {
+ // We ignore the address-significance table if we know that the object
+ // file was created by objcopy or ld -r. This is because these tools
+ // will reorder the symbols in the symbol table, invalidating the data
+ // in the address-significance table, which refers to symbols by index.
+ if (sec.sh_link != 0)
+ this->addrsigSec = &sec;
+ else if (config->icf == ICFLevel::Safe)
+ warn(toString(this) + ": --icf=safe is incompatible with object "
+ "files created using objcopy or ld -r");
+ }
+ this->sections[i] = &InputSection::discarded;
+ continue;
+ }
+
+ switch (sec.sh_type) {
+ case SHT_GROUP: {
+ // De-duplicate section groups by their signatures.
+ StringRef signature = getShtGroupSignature(objSections, sec);
+ this->sections[i] = &InputSection::discarded;
+
+
+ ArrayRef<Elf_Word> entries =
+ CHECK(obj.template getSectionContentsAsArray<Elf_Word>(&sec), this);
+ if (entries.empty())
+ fatal(toString(this) + ": empty SHT_GROUP");
+
+ // The first word of a SHT_GROUP section contains flags. Currently,
+ // the standard defines only "GRP_COMDAT" flag for the COMDAT group.
+ // An group with the empty flag doesn't define anything; such sections
+ // are just skipped.
+ if (entries[0] == 0)
+ continue;
+
+ if (entries[0] != GRP_COMDAT)
+ fatal(toString(this) + ": unsupported SHT_GROUP format");
+
+ bool isNew =
+ ignoreComdats ||
+ symtab->comdatGroups.try_emplace(CachedHashStringRef(signature), this)
+ .second;
+ if (isNew) {
+ if (config->relocatable)
+ this->sections[i] = createInputSection(sec);
+ continue;
+ }
+
+ // Otherwise, discard group members.
+ for (uint32_t secIndex : entries.slice(1)) {
+ if (secIndex >= size)
+ fatal(toString(this) +
+ ": invalid section index in group: " + Twine(secIndex));
+ this->sections[secIndex] = &InputSection::discarded;
+ }
+ break;
+ }
+ case SHT_SYMTAB_SHNDX:
+ shndxTable = CHECK(obj.getSHNDXTable(sec, objSections), this);
+ break;
+ case SHT_SYMTAB:
+ case SHT_STRTAB:
+ case SHT_NULL:
+ break;
+ default:
+ this->sections[i] = createInputSection(sec);
+ }
+
+ // .ARM.exidx sections have a reverse dependency on the InputSection they
+ // have a SHF_LINK_ORDER dependency, this is identified by the sh_link.
+ if (sec.sh_flags & SHF_LINK_ORDER) {
+ InputSectionBase *linkSec = nullptr;
+ if (sec.sh_link < this->sections.size())
+ linkSec = this->sections[sec.sh_link];
+ if (!linkSec)
+ fatal(toString(this) +
+ ": invalid sh_link index: " + Twine(sec.sh_link));
+
+ InputSection *isec = cast<InputSection>(this->sections[i]);
+ linkSec->dependentSections.push_back(isec);
+ if (!isa<InputSection>(linkSec))
+ error("a section " + isec->name +
+ " with SHF_LINK_ORDER should not refer a non-regular "
+ "section: " +
+ toString(linkSec));
+ }
+ }
+}
+
+// For ARM only, to set the EF_ARM_ABI_FLOAT_SOFT or EF_ARM_ABI_FLOAT_HARD
+// flag in the ELF Header we need to look at Tag_ABI_VFP_args to find out how
+// the input objects have been compiled.
+static void updateARMVFPArgs(const ARMAttributeParser &attributes,
+ const InputFile *f) {
+ if (!attributes.hasAttribute(ARMBuildAttrs::ABI_VFP_args))
+ // If an ABI tag isn't present then it is implicitly given the value of 0
+ // which maps to ARMBuildAttrs::BaseAAPCS. However many assembler files,
+ // including some in glibc that don't use FP args (and should have value 3)
+ // don't have the attribute so we do not consider an implicit value of 0
+ // as a clash.
+ return;
+
+ unsigned vfpArgs = attributes.getAttributeValue(ARMBuildAttrs::ABI_VFP_args);
+ ARMVFPArgKind arg;
+ switch (vfpArgs) {
+ case ARMBuildAttrs::BaseAAPCS:
+ arg = ARMVFPArgKind::Base;
+ break;
+ case ARMBuildAttrs::HardFPAAPCS:
+ arg = ARMVFPArgKind::VFP;
+ break;
+ case ARMBuildAttrs::ToolChainFPPCS:
+ // Tool chain specific convention that conforms to neither AAPCS variant.
+ arg = ARMVFPArgKind::ToolChain;
+ break;
+ case ARMBuildAttrs::CompatibleFPAAPCS:
+ // Object compatible with all conventions.
+ return;
+ default:
+ error(toString(f) + ": unknown Tag_ABI_VFP_args value: " + Twine(vfpArgs));
+ return;
+ }
+ // Follow ld.bfd and error if there is a mix of calling conventions.
+ if (config->armVFPArgs != arg && config->armVFPArgs != ARMVFPArgKind::Default)
+ error(toString(f) + ": incompatible Tag_ABI_VFP_args");
+ else
+ config->armVFPArgs = arg;
+}
+
+// The ARM support in lld makes some use of instructions that are not available
+// on all ARM architectures. Namely:
+// - Use of BLX instruction for interworking between ARM and Thumb state.
+// - Use of the extended Thumb branch encoding in relocation.
+// - Use of the MOVT/MOVW instructions in Thumb Thunks.
+// The ARM Attributes section contains information about the architecture chosen
+// at compile time. We follow the convention that if at least one input object
+// is compiled with an architecture that supports these features then lld is
+// permitted to use them.
+static void updateSupportedARMFeatures(const ARMAttributeParser &attributes) {
+ if (!attributes.hasAttribute(ARMBuildAttrs::CPU_arch))
+ return;
+ auto arch = attributes.getAttributeValue(ARMBuildAttrs::CPU_arch);
+ switch (arch) {
+ case ARMBuildAttrs::Pre_v4:
+ case ARMBuildAttrs::v4:
+ case ARMBuildAttrs::v4T:
+ // Architectures prior to v5 do not support BLX instruction
+ break;
+ case ARMBuildAttrs::v5T:
+ case ARMBuildAttrs::v5TE:
+ case ARMBuildAttrs::v5TEJ:
+ case ARMBuildAttrs::v6:
+ case ARMBuildAttrs::v6KZ:
+ case ARMBuildAttrs::v6K:
+ config->armHasBlx = true;
+ // Architectures used in pre-Cortex processors do not support
+ // The J1 = 1 J2 = 1 Thumb branch range extension, with the exception
+ // of Architecture v6T2 (arm1156t2-s and arm1156t2f-s) that do.
+ break;
+ default:
+ // All other Architectures have BLX and extended branch encoding
+ config->armHasBlx = true;
+ config->armJ1J2BranchEncoding = true;
+ if (arch != ARMBuildAttrs::v6_M && arch != ARMBuildAttrs::v6S_M)
+ // All Architectures used in Cortex processors with the exception
+ // of v6-M and v6S-M have the MOVT and MOVW instructions.
+ config->armHasMovtMovw = true;
+ break;
+ }
+}
+
+// If a source file is compiled with x86 hardware-assisted call flow control
+// enabled, the generated object file contains feature flags indicating that
+// fact. This function reads the feature flags and returns it.
+//
+// Essentially we want to read a single 32-bit value in this function, but this
+// function is rather complicated because the value is buried deep inside a
+// .note.gnu.property section.
+//
+// The section consists of one or more NOTE records. Each NOTE record consists
+// of zero or more type-length-value fields. We want to find a field of a
+// certain type. It seems a bit too much to just store a 32-bit value, perhaps
+// the ABI is unnecessarily complicated.
+template <class ELFT>
+static uint32_t readAndFeatures(ObjFile<ELFT> *obj, ArrayRef<uint8_t> data) {
+ using Elf_Nhdr = typename ELFT::Nhdr;
+ using Elf_Note = typename ELFT::Note;
+
+ uint32_t featuresSet = 0;
+ while (!data.empty()) {
+ // Read one NOTE record.
+ if (data.size() < sizeof(Elf_Nhdr))
+ fatal(toString(obj) + ": .note.gnu.property: section too short");
+
+ auto *nhdr = reinterpret_cast<const Elf_Nhdr *>(data.data());
+ if (data.size() < nhdr->getSize())
+ fatal(toString(obj) + ": .note.gnu.property: section too short");
+
+ Elf_Note note(*nhdr);
+ if (nhdr->n_type != NT_GNU_PROPERTY_TYPE_0 || note.getName() != "GNU") {
+ data = data.slice(nhdr->getSize());
+ continue;
+ }
+
+ uint32_t featureAndType = config->emachine == EM_AARCH64
+ ? GNU_PROPERTY_AARCH64_FEATURE_1_AND
+ : GNU_PROPERTY_X86_FEATURE_1_AND;
+
+ // Read a body of a NOTE record, which consists of type-length-value fields.
+ ArrayRef<uint8_t> desc = note.getDesc();
+ while (!desc.empty()) {
+ if (desc.size() < 8)
+ fatal(toString(obj) + ": .note.gnu.property: section too short");
+
+ uint32_t type = read32le(desc.data());
+ uint32_t size = read32le(desc.data() + 4);
+
+ if (type == featureAndType) {
+ // We found a FEATURE_1_AND field. There may be more than one of these
+ // in a .note.gnu.propery section, for a relocatable object we
+ // accumulate the bits set.
+ featuresSet |= read32le(desc.data() + 8);
+ }
+
+ // On 64-bit, a payload may be followed by a 4-byte padding to make its
+ // size a multiple of 8.
+ if (ELFT::Is64Bits)
+ size = alignTo(size, 8);
+
+ desc = desc.slice(size + 8); // +8 for Type and Size
+ }
+
+ // Go to next NOTE record to look for more FEATURE_1_AND descriptions.
+ data = data.slice(nhdr->getSize());
+ }
+
+ return featuresSet;
+}
+
+template <class ELFT>
+InputSectionBase *ObjFile<ELFT>::getRelocTarget(const Elf_Shdr &sec) {
+ uint32_t idx = sec.sh_info;
+ if (idx >= this->sections.size())
+ fatal(toString(this) + ": invalid relocated section index: " + Twine(idx));
+ InputSectionBase *target = this->sections[idx];
+
+ // Strictly speaking, a relocation section must be included in the
+ // group of the section it relocates. However, LLVM 3.3 and earlier
+ // would fail to do so, so we gracefully handle that case.
+ if (target == &InputSection::discarded)
+ return nullptr;
+
+ if (!target)
+ fatal(toString(this) + ": unsupported relocation reference");
+ return target;
+}
+
+// Create a regular InputSection class that has the same contents
+// as a given section.
+static InputSection *toRegularSection(MergeInputSection *sec) {
+ return make<InputSection>(sec->file, sec->flags, sec->type, sec->alignment,
+ sec->data(), sec->name);
+}
+
+template <class ELFT>
+InputSectionBase *ObjFile<ELFT>::createInputSection(const Elf_Shdr &sec) {
+ StringRef name = getSectionName(sec);
+
+ switch (sec.sh_type) {
+ case SHT_ARM_ATTRIBUTES: {
+ if (config->emachine != EM_ARM)
+ break;
+ ARMAttributeParser attributes;
+ ArrayRef<uint8_t> contents = check(this->getObj().getSectionContents(&sec));
+ attributes.Parse(contents, /*isLittle*/ config->ekind == ELF32LEKind);
+ updateSupportedARMFeatures(attributes);
+ updateARMVFPArgs(attributes, this);
+
+ // FIXME: Retain the first attribute section we see. The eglibc ARM
+ // dynamic loaders require the presence of an attribute section for dlopen
+ // to work. In a full implementation we would merge all attribute sections.
+ if (in.armAttributes == nullptr) {
+ in.armAttributes = make<InputSection>(*this, sec, name);
+ return in.armAttributes;
+ }
+ return &InputSection::discarded;
+ }
+ case SHT_LLVM_DEPENDENT_LIBRARIES: {
+ if (config->relocatable)
+ break;
+ ArrayRef<char> data =
+ CHECK(this->getObj().template getSectionContentsAsArray<char>(&sec), this);
+ if (!data.empty() && data.back() != '\0') {
+ error(toString(this) +
+ ": corrupted dependent libraries section (unterminated string): " +
+ name);
+ return &InputSection::discarded;
+ }
+ for (const char *d = data.begin(), *e = data.end(); d < e;) {
+ StringRef s(d);
+ addDependentLibrary(s, this);
+ d += s.size() + 1;
+ }
+ return &InputSection::discarded;
+ }
+ case SHT_RELA:
+ case SHT_REL: {
+ // Find a relocation target section and associate this section with that.
+ // Target may have been discarded if it is in a different section group
+ // and the group is discarded, even though it's a violation of the
+ // spec. We handle that situation gracefully by discarding dangling
+ // relocation sections.
+ InputSectionBase *target = getRelocTarget(sec);
+ if (!target)
+ return nullptr;
+
+ // This section contains relocation information.
+ // If -r is given, we do not interpret or apply relocation
+ // but just copy relocation sections to output.
+ if (config->relocatable) {
+ InputSection *relocSec = make<InputSection>(*this, sec, name);
+ // We want to add a dependency to target, similar like we do for
+ // -emit-relocs below. This is useful for the case when linker script
+ // contains the "/DISCARD/". It is perhaps uncommon to use a script with
+ // -r, but we faced it in the Linux kernel and have to handle such case
+ // and not to crash.
+ target->dependentSections.push_back(relocSec);
+ return relocSec;
+ }
+
+ if (target->firstRelocation)
+ fatal(toString(this) +
+ ": multiple relocation sections to one section are not supported");
+
+ // ELF spec allows mergeable sections with relocations, but they are
+ // rare, and it is in practice hard to merge such sections by contents,
+ // because applying relocations at end of linking changes section
+ // contents. So, we simply handle such sections as non-mergeable ones.
+ // Degrading like this is acceptable because section merging is optional.
+ if (auto *ms = dyn_cast<MergeInputSection>(target)) {
+ target = toRegularSection(ms);
+ this->sections[sec.sh_info] = target;
+ }
+
+ if (sec.sh_type == SHT_RELA) {
+ ArrayRef<Elf_Rela> rels = CHECK(getObj().relas(&sec), this);
+ target->firstRelocation = rels.begin();
+ target->numRelocations = rels.size();
+ target->areRelocsRela = true;
+ } else {
+ ArrayRef<Elf_Rel> rels = CHECK(getObj().rels(&sec), this);
+ target->firstRelocation = rels.begin();
+ target->numRelocations = rels.size();
+ target->areRelocsRela = false;
+ }
+ assert(isUInt<31>(target->numRelocations));
+
+ // Relocation sections processed by the linker are usually removed
+ // from the output, so returning `nullptr` for the normal case.
+ // However, if -emit-relocs is given, we need to leave them in the output.
+ // (Some post link analysis tools need this information.)
+ if (config->emitRelocs) {
+ InputSection *relocSec = make<InputSection>(*this, sec, name);
+ // We will not emit relocation section if target was discarded.
+ target->dependentSections.push_back(relocSec);
+ return relocSec;
+ }
+ return nullptr;
+ }
+ }
+
+ // The GNU linker uses .note.GNU-stack section as a marker indicating
+ // that the code in the object file does not expect that the stack is
+ // executable (in terms of NX bit). If all input files have the marker,
+ // the GNU linker adds a PT_GNU_STACK segment to tells the loader to
+ // make the stack non-executable. Most object files have this section as
+ // of 2017.
+ //
+ // But making the stack non-executable is a norm today for security
+ // reasons. Failure to do so may result in a serious security issue.
+ // Therefore, we make LLD always add PT_GNU_STACK unless it is
+ // explicitly told to do otherwise (by -z execstack). Because the stack
+ // executable-ness is controlled solely by command line options,
+ // .note.GNU-stack sections are simply ignored.
+ if (name == ".note.GNU-stack")
+ return &InputSection::discarded;
+
+ // Object files that use processor features such as Intel Control-Flow
+ // Enforcement (CET) or AArch64 Branch Target Identification BTI, use a
+ // .note.gnu.property section containing a bitfield of feature bits like the
+ // GNU_PROPERTY_X86_FEATURE_1_IBT flag. Read a bitmap containing the flag.
+ //
+ // Since we merge bitmaps from multiple object files to create a new
+ // .note.gnu.property containing a single AND'ed bitmap, we discard an input
+ // file's .note.gnu.property section.
+ if (name == ".note.gnu.property") {
+ ArrayRef<uint8_t> contents = check(this->getObj().getSectionContents(&sec));
+ this->andFeatures = readAndFeatures(this, contents);
+ return &InputSection::discarded;
+ }
+
+ // Split stacks is a feature to support a discontiguous stack,
+ // commonly used in the programming language Go. For the details,
+ // see https://gcc.gnu.org/wiki/SplitStacks. An object file compiled
+ // for split stack will include a .note.GNU-split-stack section.
+ if (name == ".note.GNU-split-stack") {
+ if (config->relocatable) {
+ error("cannot mix split-stack and non-split-stack in a relocatable link");
+ return &InputSection::discarded;
+ }
+ this->splitStack = true;
+ return &InputSection::discarded;
+ }
+
+ // An object file cmpiled for split stack, but where some of the
+ // functions were compiled with the no_split_stack_attribute will
+ // include a .note.GNU-no-split-stack section.
+ if (name == ".note.GNU-no-split-stack") {
+ this->someNoSplitStack = true;
+ return &InputSection::discarded;
+ }
+
+ // The linkonce feature is a sort of proto-comdat. Some glibc i386 object
+ // files contain definitions of symbol "__x86.get_pc_thunk.bx" in linkonce
+ // sections. Drop those sections to avoid duplicate symbol errors.
+ // FIXME: This is glibc PR20543, we should remove this hack once that has been
+ // fixed for a while.
+ if (name == ".gnu.linkonce.t.__x86.get_pc_thunk.bx" ||
+ name == ".gnu.linkonce.t.__i686.get_pc_thunk.bx")
+ return &InputSection::discarded;
+
+ // If we are creating a new .build-id section, strip existing .build-id
+ // sections so that the output won't have more than one .build-id.
+ // This is not usually a problem because input object files normally don't
+ // have .build-id sections, but you can create such files by
+ // "ld.{bfd,gold,lld} -r --build-id", and we want to guard against it.
+ if (name == ".note.gnu.build-id" && config->buildId != BuildIdKind::None)
+ return &InputSection::discarded;
+
+ // The linker merges EH (exception handling) frames and creates a
+ // .eh_frame_hdr section for runtime. So we handle them with a special
+ // class. For relocatable outputs, they are just passed through.
+ if (name == ".eh_frame" && !config->relocatable)
+ return make<EhInputSection>(*this, sec, name);
+
+ if (shouldMerge(sec))
+ return make<MergeInputSection>(*this, sec, name);
+ return make<InputSection>(*this, sec, name);
+}
+
+template <class ELFT>
+StringRef ObjFile<ELFT>::getSectionName(const Elf_Shdr &sec) {
+ return CHECK(getObj().getSectionName(&sec, sectionStringTable), this);
+}
+
+// Initialize this->Symbols. this->Symbols is a parallel array as
+// its corresponding ELF symbol table.
+template <class ELFT> void ObjFile<ELFT>::initializeSymbols() {
+ ArrayRef<Elf_Sym> eSyms = this->getELFSyms<ELFT>();
+ this->symbols.resize(eSyms.size());
+
+ // Our symbol table may have already been partially initialized
+ // because of LazyObjFile.
+ for (size_t i = 0, end = eSyms.size(); i != end; ++i)
+ if (!this->symbols[i] && eSyms[i].getBinding() != STB_LOCAL)
+ this->symbols[i] =
+ symtab->insert(CHECK(eSyms[i].getName(this->stringTable), this));
+
+ // Fill this->Symbols. A symbol is either local or global.
+ for (size_t i = 0, end = eSyms.size(); i != end; ++i) {
+ const Elf_Sym &eSym = eSyms[i];
+
+ // Read symbol attributes.
+ uint32_t secIdx = getSectionIndex(eSym);
+ if (secIdx >= this->sections.size())
+ fatal(toString(this) + ": invalid section index: " + Twine(secIdx));
+
+ InputSectionBase *sec = this->sections[secIdx];
+ uint8_t binding = eSym.getBinding();
+ uint8_t stOther = eSym.st_other;
+ uint8_t type = eSym.getType();
+ uint64_t value = eSym.st_value;
+ uint64_t size = eSym.st_size;
+ StringRefZ name = this->stringTable.data() + eSym.st_name;
+
+ // Handle local symbols. Local symbols are not added to the symbol
+ // table because they are not visible from other object files. We
+ // allocate symbol instances and add their pointers to Symbols.
+ if (binding == STB_LOCAL) {
+ if (eSym.getType() == STT_FILE)
+ sourceFile = CHECK(eSym.getName(this->stringTable), this);
+
+ if (this->stringTable.size() <= eSym.st_name)
+ fatal(toString(this) + ": invalid symbol name offset");
+
+ if (eSym.st_shndx == SHN_UNDEF)
+ this->symbols[i] = make<Undefined>(this, name, binding, stOther, type);
+ else if (sec == &InputSection::discarded)
+ this->symbols[i] = make<Undefined>(this, name, binding, stOther, type,
+ /*DiscardedSecIdx=*/secIdx);
+ else
+ this->symbols[i] =
+ make<Defined>(this, name, binding, stOther, type, value, size, sec);
+ continue;
+ }
+
+ // Handle global undefined symbols.
+ if (eSym.st_shndx == SHN_UNDEF) {
+ this->symbols[i]->resolve(Undefined{this, name, binding, stOther, type});
+ continue;
+ }
+
+ // Handle global common symbols.
+ if (eSym.st_shndx == SHN_COMMON) {
+ if (value == 0 || value >= UINT32_MAX)
+ fatal(toString(this) + ": common symbol '" + StringRef(name.data) +
+ "' has invalid alignment: " + Twine(value));
+ this->symbols[i]->resolve(
+ CommonSymbol{this, name, binding, stOther, type, value, size});
+ continue;
+ }
+
+ // If a defined symbol is in a discarded section, handle it as if it
+ // were an undefined symbol. Such symbol doesn't comply with the
+ // standard, but in practice, a .eh_frame often directly refer
+ // COMDAT member sections, and if a comdat group is discarded, some
+ // defined symbol in a .eh_frame becomes dangling symbols.
+ if (sec == &InputSection::discarded) {
+ this->symbols[i]->resolve(
+ Undefined{this, name, binding, stOther, type, secIdx});
+ continue;
+ }
+
+ // Handle global defined symbols.
+ if (binding == STB_GLOBAL || binding == STB_WEAK ||
+ binding == STB_GNU_UNIQUE) {
+ this->symbols[i]->resolve(
+ Defined{this, name, binding, stOther, type, value, size, sec});
+ continue;
+ }
+
+ fatal(toString(this) + ": unexpected binding: " + Twine((int)binding));
+ }
+}
+
+ArchiveFile::ArchiveFile(std::unique_ptr<Archive> &&file)
+ : InputFile(ArchiveKind, file->getMemoryBufferRef()),
+ file(std::move(file)) {}
+
+void ArchiveFile::parse() {
+ for (const Archive::Symbol &sym : file->symbols())
+ symtab->addSymbol(LazyArchive{*this, sym});
+}
+
+// Returns a buffer pointing to a member file containing a given symbol.
+void ArchiveFile::fetch(const Archive::Symbol &sym) {
+ Archive::Child c =
+ CHECK(sym.getMember(), toString(this) +
+ ": could not get the member for symbol " +
+ toELFString(sym));
+
+ if (!seen.insert(c.getChildOffset()).second)
+ return;
+
+ MemoryBufferRef mb =
+ CHECK(c.getMemoryBufferRef(),
+ toString(this) +
+ ": could not get the buffer for the member defining symbol " +
+ toELFString(sym));
+
+ if (tar && c.getParent()->isThin())
+ tar->append(relativeToRoot(CHECK(c.getFullName(), this)), mb.getBuffer());
+
+ InputFile *file = createObjectFile(
+ mb, getName(), c.getParent()->isThin() ? 0 : c.getChildOffset());
+ file->groupId = groupId;
+ parseFile(file);
+}
+
+unsigned SharedFile::vernauxNum;
+
+// Parse the version definitions in the object file if present, and return a
+// vector whose nth element contains a pointer to the Elf_Verdef for version
+// identifier n. Version identifiers that are not definitions map to nullptr.
+template <typename ELFT>
+static std::vector<const void *> parseVerdefs(const uint8_t *base,
+ const typename ELFT::Shdr *sec) {
+ if (!sec)
+ return {};
+
+ // We cannot determine the largest verdef identifier without inspecting
+ // every Elf_Verdef, but both bfd and gold assign verdef identifiers
+ // sequentially starting from 1, so we predict that the largest identifier
+ // will be verdefCount.
+ unsigned verdefCount = sec->sh_info;
+ std::vector<const void *> verdefs(verdefCount + 1);
+
+ // Build the Verdefs array by following the chain of Elf_Verdef objects
+ // from the start of the .gnu.version_d section.
+ const uint8_t *verdef = base + sec->sh_offset;
+ for (unsigned i = 0; i != verdefCount; ++i) {
+ auto *curVerdef = reinterpret_cast<const typename ELFT::Verdef *>(verdef);
+ verdef += curVerdef->vd_next;
+ unsigned verdefIndex = curVerdef->vd_ndx;
+ verdefs.resize(verdefIndex + 1);
+ verdefs[verdefIndex] = curVerdef;
+ }
+ return verdefs;
+}
+
+// We do not usually care about alignments of data in shared object
+// files because the loader takes care of it. However, if we promote a
+// DSO symbol to point to .bss due to copy relocation, we need to keep
+// the original alignment requirements. We infer it in this function.
+template <typename ELFT>
+static uint64_t getAlignment(ArrayRef<typename ELFT::Shdr> sections,
+ const typename ELFT::Sym &sym) {
+ uint64_t ret = UINT64_MAX;
+ if (sym.st_value)
+ ret = 1ULL << countTrailingZeros((uint64_t)sym.st_value);
+ if (0 < sym.st_shndx && sym.st_shndx < sections.size())
+ ret = std::min<uint64_t>(ret, sections[sym.st_shndx].sh_addralign);
+ return (ret > UINT32_MAX) ? 0 : ret;
+}
+
+// Fully parse the shared object file.
+//
+// This function parses symbol versions. If a DSO has version information,
+// the file has a ".gnu.version_d" section which contains symbol version
+// definitions. Each symbol is associated to one version through a table in
+// ".gnu.version" section. That table is a parallel array for the symbol
+// table, and each table entry contains an index in ".gnu.version_d".
+//
+// The special index 0 is reserved for VERF_NDX_LOCAL and 1 is for
+// VER_NDX_GLOBAL. There's no table entry for these special versions in
+// ".gnu.version_d".
+//
+// The file format for symbol versioning is perhaps a bit more complicated
+// than necessary, but you can easily understand the code if you wrap your
+// head around the data structure described above.
+template <class ELFT> void SharedFile::parse() {
+ using Elf_Dyn = typename ELFT::Dyn;
+ using Elf_Shdr = typename ELFT::Shdr;
+ using Elf_Sym = typename ELFT::Sym;
+ using Elf_Verdef = typename ELFT::Verdef;
+ using Elf_Versym = typename ELFT::Versym;
+
+ ArrayRef<Elf_Dyn> dynamicTags;
+ const ELFFile<ELFT> obj = this->getObj<ELFT>();
+ ArrayRef<Elf_Shdr> sections = CHECK(obj.sections(), this);
+
+ const Elf_Shdr *versymSec = nullptr;
+ const Elf_Shdr *verdefSec = nullptr;
+
+ // Search for .dynsym, .dynamic, .symtab, .gnu.version and .gnu.version_d.
+ for (const Elf_Shdr &sec : sections) {
+ switch (sec.sh_type) {
+ default:
+ continue;
+ case SHT_DYNAMIC:
+ dynamicTags =
+ CHECK(obj.template getSectionContentsAsArray<Elf_Dyn>(&sec), this);
+ break;
+ case SHT_GNU_versym:
+ versymSec = &sec;
+ break;
+ case SHT_GNU_verdef:
+ verdefSec = &sec;
+ break;
+ }
+ }
+
+ if (versymSec && numELFSyms == 0) {
+ error("SHT_GNU_versym should be associated with symbol table");
+ return;
+ }
+
+ // Search for a DT_SONAME tag to initialize this->soName.
+ for (const Elf_Dyn &dyn : dynamicTags) {
+ if (dyn.d_tag == DT_NEEDED) {
+ uint64_t val = dyn.getVal();
+ if (val >= this->stringTable.size())
+ fatal(toString(this) + ": invalid DT_NEEDED entry");
+ dtNeeded.push_back(this->stringTable.data() + val);
+ } else if (dyn.d_tag == DT_SONAME) {
+ uint64_t val = dyn.getVal();
+ if (val >= this->stringTable.size())
+ fatal(toString(this) + ": invalid DT_SONAME entry");
+ soName = this->stringTable.data() + val;
+ }
+ }
+
+ // DSOs are uniquified not by filename but by soname.
+ DenseMap<StringRef, SharedFile *>::iterator it;
+ bool wasInserted;
+ std::tie(it, wasInserted) = symtab->soNames.try_emplace(soName, this);
+
+ // If a DSO appears more than once on the command line with and without
+ // --as-needed, --no-as-needed takes precedence over --as-needed because a
+ // user can add an extra DSO with --no-as-needed to force it to be added to
+ // the dependency list.
+ it->second->isNeeded |= isNeeded;
+ if (!wasInserted)
+ return;
+
+ sharedFiles.push_back(this);
+
+ verdefs = parseVerdefs<ELFT>(obj.base(), verdefSec);
+
+ // Parse ".gnu.version" section which is a parallel array for the symbol
+ // table. If a given file doesn't have a ".gnu.version" section, we use
+ // VER_NDX_GLOBAL.
+ size_t size = numELFSyms - firstGlobal;
+ std::vector<uint32_t> versyms(size, VER_NDX_GLOBAL);
+ if (versymSec) {
+ ArrayRef<Elf_Versym> versym =
+ CHECK(obj.template getSectionContentsAsArray<Elf_Versym>(versymSec),
+ this)
+ .slice(firstGlobal);
+ for (size_t i = 0; i < size; ++i)
+ versyms[i] = versym[i].vs_index;
+ }
+
+ // System libraries can have a lot of symbols with versions. Using a
+ // fixed buffer for computing the versions name (foo@ver) can save a
+ // lot of allocations.
+ SmallString<0> versionedNameBuffer;
+
+ // Add symbols to the symbol table.
+ ArrayRef<Elf_Sym> syms = this->getGlobalELFSyms<ELFT>();
+ for (size_t i = 0; i < syms.size(); ++i) {
+ const Elf_Sym &sym = syms[i];
+
+ // ELF spec requires that all local symbols precede weak or global
+ // symbols in each symbol table, and the index of first non-local symbol
+ // is stored to sh_info. If a local symbol appears after some non-local
+ // symbol, that's a violation of the spec.
+ StringRef name = CHECK(sym.getName(this->stringTable), this);
+ if (sym.getBinding() == STB_LOCAL) {
+ warn("found local symbol '" + name +
+ "' in global part of symbol table in file " + toString(this));
+ continue;
+ }
+
+ if (sym.isUndefined()) {
+ Symbol *s = symtab->addSymbol(
+ Undefined{this, name, sym.getBinding(), sym.st_other, sym.getType()});
+ s->exportDynamic = true;
+ continue;
+ }
+
+ // MIPS BFD linker puts _gp_disp symbol into DSO files and incorrectly
+ // assigns VER_NDX_LOCAL to this section global symbol. Here is a
+ // workaround for this bug.
+ uint32_t idx = versyms[i] & ~VERSYM_HIDDEN;
+ if (config->emachine == EM_MIPS && idx == VER_NDX_LOCAL &&
+ name == "_gp_disp")
+ continue;
+
+ uint32_t alignment = getAlignment<ELFT>(sections, sym);
+ if (!(versyms[i] & VERSYM_HIDDEN)) {
+ symtab->addSymbol(SharedSymbol{*this, name, sym.getBinding(),
+ sym.st_other, sym.getType(), sym.st_value,
+ sym.st_size, alignment, idx});
+ }
+
+ // Also add the symbol with the versioned name to handle undefined symbols
+ // with explicit versions.
+ if (idx == VER_NDX_GLOBAL)
+ continue;
+
+ if (idx >= verdefs.size() || idx == VER_NDX_LOCAL) {
+ error("corrupt input file: version definition index " + Twine(idx) +
+ " for symbol " + name + " is out of bounds\n>>> defined in " +
+ toString(this));
+ continue;
+ }
+
+ StringRef verName =
+ this->stringTable.data() +
+ reinterpret_cast<const Elf_Verdef *>(verdefs[idx])->getAux()->vda_name;
+ versionedNameBuffer.clear();
+ name = (name + "@" + verName).toStringRef(versionedNameBuffer);
+ symtab->addSymbol(SharedSymbol{*this, saver.save(name), sym.getBinding(),
+ sym.st_other, sym.getType(), sym.st_value,
+ sym.st_size, alignment, idx});
+ }
+}
+
+static ELFKind getBitcodeELFKind(const Triple &t) {
+ if (t.isLittleEndian())
+ return t.isArch64Bit() ? ELF64LEKind : ELF32LEKind;
+ return t.isArch64Bit() ? ELF64BEKind : ELF32BEKind;
+}
+
+static uint8_t getBitcodeMachineKind(StringRef path, const Triple &t) {
+ switch (t.getArch()) {
+ case Triple::aarch64:
+ return EM_AARCH64;
+ case Triple::amdgcn:
+ case Triple::r600:
+ return EM_AMDGPU;
+ case Triple::arm:
+ case Triple::thumb:
+ return EM_ARM;
+ case Triple::avr:
+ return EM_AVR;
+ case Triple::mips:
+ case Triple::mipsel:
+ case Triple::mips64:
+ case Triple::mips64el:
+ return EM_MIPS;
+ case Triple::msp430:
+ return EM_MSP430;
+ case Triple::ppc:
+ return EM_PPC;
+ case Triple::ppc64:
+ case Triple::ppc64le:
+ return EM_PPC64;
+ case Triple::riscv32:
+ case Triple::riscv64:
+ return EM_RISCV;
+ case Triple::x86:
+ return t.isOSIAMCU() ? EM_IAMCU : EM_386;
+ case Triple::x86_64:
+ return EM_X86_64;
+ default:
+ error(path + ": could not infer e_machine from bitcode target triple " +
+ t.str());
+ return EM_NONE;
+ }
+}
+
+BitcodeFile::BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
+ uint64_t offsetInArchive)
+ : InputFile(BitcodeKind, mb) {
+ this->archiveName = archiveName;
+
+ std::string path = mb.getBufferIdentifier().str();
+ if (config->thinLTOIndexOnly)
+ path = replaceThinLTOSuffix(mb.getBufferIdentifier());
+
+ // ThinLTO assumes that all MemoryBufferRefs given to it have a unique
+ // name. If two archives define two members with the same name, this
+ // causes a collision which result in only one of the objects being taken
+ // into consideration at LTO time (which very likely causes undefined
+ // symbols later in the link stage). So we append file offset to make
+ // filename unique.
+ StringRef name = archiveName.empty()
+ ? saver.save(path)
+ : saver.save(archiveName + "(" + path + " at " +
+ utostr(offsetInArchive) + ")");
+ MemoryBufferRef mbref(mb.getBuffer(), name);
+
+ obj = CHECK(lto::InputFile::create(mbref), this);
+
+ Triple t(obj->getTargetTriple());
+ ekind = getBitcodeELFKind(t);
+ emachine = getBitcodeMachineKind(mb.getBufferIdentifier(), t);
+}
+
+static uint8_t mapVisibility(GlobalValue::VisibilityTypes gvVisibility) {
+ switch (gvVisibility) {
+ case GlobalValue::DefaultVisibility:
+ return STV_DEFAULT;
+ case GlobalValue::HiddenVisibility:
+ return STV_HIDDEN;
+ case GlobalValue::ProtectedVisibility:
+ return STV_PROTECTED;
+ }
+ llvm_unreachable("unknown visibility");
+}
+
+template <class ELFT>
+static Symbol *createBitcodeSymbol(const std::vector<bool> &keptComdats,
+ const lto::InputFile::Symbol &objSym,
+ BitcodeFile &f) {
+ StringRef name = saver.save(objSym.getName());
+ uint8_t binding = objSym.isWeak() ? STB_WEAK : STB_GLOBAL;
+ uint8_t type = objSym.isTLS() ? STT_TLS : STT_NOTYPE;
+ uint8_t visibility = mapVisibility(objSym.getVisibility());
+ bool canOmitFromDynSym = objSym.canBeOmittedFromSymbolTable();
+
+ int c = objSym.getComdatIndex();
+ if (objSym.isUndefined() || (c != -1 && !keptComdats[c])) {
+ Undefined New(&f, name, binding, visibility, type);
+ if (canOmitFromDynSym)
+ New.exportDynamic = false;
+ return symtab->addSymbol(New);
+ }
+
+ if (objSym.isCommon())
+ return symtab->addSymbol(
+ CommonSymbol{&f, name, binding, visibility, STT_OBJECT,
+ objSym.getCommonAlignment(), objSym.getCommonSize()});
+
+ Defined New(&f, name, binding, visibility, type, 0, 0, nullptr);
+ if (canOmitFromDynSym)
+ New.exportDynamic = false;
+ return symtab->addSymbol(New);
+}
+
+template <class ELFT> void BitcodeFile::parse() {
+ std::vector<bool> keptComdats;
+ for (StringRef s : obj->getComdatTable())
+ keptComdats.push_back(
+ symtab->comdatGroups.try_emplace(CachedHashStringRef(s), this).second);
+
+ for (const lto::InputFile::Symbol &objSym : obj->symbols())
+ symbols.push_back(createBitcodeSymbol<ELFT>(keptComdats, objSym, *this));
+
+ for (auto l : obj->getDependentLibraries())
+ addDependentLibrary(l, this);
+}
+
+void BinaryFile::parse() {
+ ArrayRef<uint8_t> data = arrayRefFromStringRef(mb.getBuffer());
+ auto *section = make<InputSection>(this, SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
+ 8, data, ".data");
+ sections.push_back(section);
+
+ // For each input file foo that is embedded to a result as a binary
+ // blob, we define _binary_foo_{start,end,size} symbols, so that
+ // user programs can access blobs by name. Non-alphanumeric
+ // characters in a filename are replaced with underscore.
+ std::string s = "_binary_" + mb.getBufferIdentifier().str();
+ for (size_t i = 0; i < s.size(); ++i)
+ if (!isAlnum(s[i]))
+ s[i] = '_';
+
+ symtab->addSymbol(Defined{nullptr, saver.save(s + "_start"), STB_GLOBAL,
+ STV_DEFAULT, STT_OBJECT, 0, 0, section});
+ symtab->addSymbol(Defined{nullptr, saver.save(s + "_end"), STB_GLOBAL,
+ STV_DEFAULT, STT_OBJECT, data.size(), 0, section});
+ symtab->addSymbol(Defined{nullptr, saver.save(s + "_size"), STB_GLOBAL,
+ STV_DEFAULT, STT_OBJECT, data.size(), 0, nullptr});
+}
+
+InputFile *elf::createObjectFile(MemoryBufferRef mb, StringRef archiveName,
+ uint64_t offsetInArchive) {
+ if (isBitcode(mb))
+ return make<BitcodeFile>(mb, archiveName, offsetInArchive);
+
+ switch (getELFKind(mb, archiveName)) {
+ case ELF32LEKind:
+ return make<ObjFile<ELF32LE>>(mb, archiveName);
+ case ELF32BEKind:
+ return make<ObjFile<ELF32BE>>(mb, archiveName);
+ case ELF64LEKind:
+ return make<ObjFile<ELF64LE>>(mb, archiveName);
+ case ELF64BEKind:
+ return make<ObjFile<ELF64BE>>(mb, archiveName);
+ default:
+ llvm_unreachable("getELFKind");
+ }
+}
+
+void LazyObjFile::fetch() {
+ if (mb.getBuffer().empty())
+ return;
+
+ InputFile *file = createObjectFile(mb, archiveName, offsetInArchive);
+ file->groupId = groupId;
+
+ mb = {};
+
+ // Copy symbol vector so that the new InputFile doesn't have to
+ // insert the same defined symbols to the symbol table again.
+ file->symbols = std::move(symbols);
+
+ parseFile(file);
+}
+
+template <class ELFT> void LazyObjFile::parse() {
+ using Elf_Sym = typename ELFT::Sym;
+
+ // A lazy object file wraps either a bitcode file or an ELF file.
+ if (isBitcode(this->mb)) {
+ std::unique_ptr<lto::InputFile> obj =
+ CHECK(lto::InputFile::create(this->mb), this);
+ for (const lto::InputFile::Symbol &sym : obj->symbols()) {
+ if (sym.isUndefined())
+ continue;
+ symtab->addSymbol(LazyObject{*this, saver.save(sym.getName())});
+ }
+ return;
+ }
+
+ if (getELFKind(this->mb, archiveName) != config->ekind) {
+ error("incompatible file: " + this->mb.getBufferIdentifier());
+ return;
+ }
+
+ // Find a symbol table.
+ ELFFile<ELFT> obj = check(ELFFile<ELFT>::create(mb.getBuffer()));
+ ArrayRef<typename ELFT::Shdr> sections = CHECK(obj.sections(), this);
+
+ for (const typename ELFT::Shdr &sec : sections) {
+ if (sec.sh_type != SHT_SYMTAB)
+ continue;
+
+ // A symbol table is found.
+ ArrayRef<Elf_Sym> eSyms = CHECK(obj.symbols(&sec), this);
+ uint32_t firstGlobal = sec.sh_info;
+ StringRef strtab = CHECK(obj.getStringTableForSymtab(sec, sections), this);
+ this->symbols.resize(eSyms.size());
+
+ // Get existing symbols or insert placeholder symbols.
+ for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i)
+ if (eSyms[i].st_shndx != SHN_UNDEF)
+ this->symbols[i] = symtab->insert(CHECK(eSyms[i].getName(strtab), this));
+
+ // Replace existing symbols with LazyObject symbols.
+ //
+ // resolve() may trigger this->fetch() if an existing symbol is an
+ // undefined symbol. If that happens, this LazyObjFile has served
+ // its purpose, and we can exit from the loop early.
+ for (Symbol *sym : this->symbols) {
+ if (!sym)
+ continue;
+ sym->resolve(LazyObject{*this, sym->getName()});
+
+ // MemoryBuffer is emptied if this file is instantiated as ObjFile.
+ if (mb.getBuffer().empty())
+ return;
+ }
+ return;
+ }
+}
+
+std::string elf::replaceThinLTOSuffix(StringRef path) {
+ StringRef suffix = config->thinLTOObjectSuffixReplace.first;
+ StringRef repl = config->thinLTOObjectSuffixReplace.second;
+
+ if (path.consume_back(suffix))
+ return (path + repl).str();
+ return path;
+}
+
+template void BitcodeFile::parse<ELF32LE>();
+template void BitcodeFile::parse<ELF32BE>();
+template void BitcodeFile::parse<ELF64LE>();
+template void BitcodeFile::parse<ELF64BE>();
+
+template void LazyObjFile::parse<ELF32LE>();
+template void LazyObjFile::parse<ELF32BE>();
+template void LazyObjFile::parse<ELF64LE>();
+template void LazyObjFile::parse<ELF64BE>();
+
+template class elf::ObjFile<ELF32LE>;
+template class elf::ObjFile<ELF32BE>;
+template class elf::ObjFile<ELF64LE>;
+template class elf::ObjFile<ELF64BE>;
+
+template void SharedFile::parse<ELF32LE>();
+template void SharedFile::parse<ELF32BE>();
+template void SharedFile::parse<ELF64LE>();
+template void SharedFile::parse<ELF64BE>();
generated by cgit v1.2.3 (git 2.25.1) at 2025-12-09 08:43:47 +0000