forked from OSchip/llvm-project
1262 lines
47 KiB
C++
1262 lines
47 KiB
C++
//===- InputFiles.cpp -----------------------------------------------------===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "InputFiles.h"
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#include "InputSection.h"
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#include "LinkerScript.h"
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#include "SymbolTable.h"
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#include "Symbols.h"
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#include "SyntheticSections.h"
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#include "lld/Common/ErrorHandler.h"
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#include "lld/Common/Memory.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/CodeGen/Analysis.h"
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#include "llvm/DebugInfo/DWARF/DWARFContext.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Module.h"
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#include "llvm/LTO/LTO.h"
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#include "llvm/MC/StringTableBuilder.h"
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#include "llvm/Object/ELFObjectFile.h"
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#include "llvm/Support/ARMAttributeParser.h"
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#include "llvm/Support/ARMBuildAttributes.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/TarWriter.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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using namespace llvm::ELF;
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using namespace llvm::object;
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using namespace llvm::sys;
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using namespace llvm::sys::fs;
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using namespace lld;
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using namespace lld::elf;
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std::vector<BinaryFile *> elf::BinaryFiles;
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std::vector<BitcodeFile *> elf::BitcodeFiles;
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std::vector<InputFile *> elf::ObjectFiles;
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std::vector<InputFile *> elf::SharedFiles;
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TarWriter *elf::Tar;
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InputFile::InputFile(Kind K, MemoryBufferRef M) : MB(M), FileKind(K) {}
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Optional<MemoryBufferRef> elf::readFile(StringRef Path) {
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// The --chroot option changes our virtual root directory.
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// This is useful when you are dealing with files created by --reproduce.
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if (!Config->Chroot.empty() && Path.startswith("/"))
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Path = Saver.save(Config->Chroot + Path);
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log(Path);
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auto MBOrErr = MemoryBuffer::getFile(Path);
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if (auto EC = MBOrErr.getError()) {
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error("cannot open " + Path + ": " + EC.message());
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return None;
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}
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std::unique_ptr<MemoryBuffer> &MB = *MBOrErr;
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MemoryBufferRef MBRef = MB->getMemBufferRef();
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make<std::unique_ptr<MemoryBuffer>>(std::move(MB)); // take MB ownership
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if (Tar)
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Tar->append(relativeToRoot(Path), MBRef.getBuffer());
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return MBRef;
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}
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// Concatenates arguments to construct a string representing an error location.
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static std::string createFileLineMsg(StringRef Path, unsigned Line) {
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std::string Filename = path::filename(Path);
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std::string Lineno = ":" + std::to_string(Line);
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if (Filename == Path)
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return Filename + Lineno;
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return Filename + Lineno + " (" + Path.str() + Lineno + ")";
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}
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template <class ELFT>
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static std::string getSrcMsgAux(ObjFile<ELFT> &File, const Symbol &Sym,
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InputSectionBase &Sec, uint64_t Offset) {
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// In DWARF, functions and variables are stored to different places.
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// First, lookup a function for a given offset.
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if (Optional<DILineInfo> Info = File.getDILineInfo(&Sec, Offset))
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return createFileLineMsg(Info->FileName, Info->Line);
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// If it failed, lookup again as a variable.
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if (Optional<std::pair<std::string, unsigned>> FileLine =
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File.getVariableLoc(Sym.getName()))
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return createFileLineMsg(FileLine->first, FileLine->second);
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// File.SourceFile contains STT_FILE symbol, and that is a last resort.
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return File.SourceFile;
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}
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std::string InputFile::getSrcMsg(const Symbol &Sym, InputSectionBase &Sec,
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uint64_t Offset) {
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if (kind() != ObjKind)
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return "";
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switch (Config->EKind) {
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default:
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llvm_unreachable("Invalid kind");
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case ELF32LEKind:
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return getSrcMsgAux(cast<ObjFile<ELF32LE>>(*this), Sym, Sec, Offset);
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case ELF32BEKind:
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return getSrcMsgAux(cast<ObjFile<ELF32BE>>(*this), Sym, Sec, Offset);
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case ELF64LEKind:
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return getSrcMsgAux(cast<ObjFile<ELF64LE>>(*this), Sym, Sec, Offset);
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case ELF64BEKind:
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return getSrcMsgAux(cast<ObjFile<ELF64BE>>(*this), Sym, Sec, Offset);
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}
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}
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template <class ELFT> void ObjFile<ELFT>::initializeDwarf() {
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Dwarf = llvm::make_unique<DWARFContext>(make_unique<LLDDwarfObj<ELFT>>(this));
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const DWARFObject &Obj = Dwarf->getDWARFObj();
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DwarfLine.reset(new DWARFDebugLine);
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DWARFDataExtractor LineData(Obj, Obj.getLineSection(), Config->IsLE,
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Config->Wordsize);
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for (std::unique_ptr<DWARFCompileUnit> &CU : Dwarf->compile_units()) {
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const DWARFDebugLine::LineTable *LT = Dwarf->getLineTableForUnit(CU.get());
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if (!LT)
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continue;
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LineTables.push_back(LT);
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// Loop over variable records and insert them to VariableLoc.
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for (const auto &Entry : CU->dies()) {
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DWARFDie Die(CU.get(), &Entry);
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// Skip all tags that are not variables.
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if (Die.getTag() != dwarf::DW_TAG_variable)
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continue;
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// Skip if a local variable because we don't need them for generating
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// error messages. In general, only non-local symbols can fail to be
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// linked.
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if (!dwarf::toUnsigned(Die.find(dwarf::DW_AT_external), 0))
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continue;
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// Get the source filename index for the variable.
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unsigned File = dwarf::toUnsigned(Die.find(dwarf::DW_AT_decl_file), 0);
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if (!LT->hasFileAtIndex(File))
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continue;
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// Get the line number on which the variable is declared.
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unsigned Line = dwarf::toUnsigned(Die.find(dwarf::DW_AT_decl_line), 0);
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// Get the name of the variable and add the collected information to
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// VariableLoc. Usually Name is non-empty, but it can be empty if the
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// input object file lacks some debug info.
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StringRef Name = dwarf::toString(Die.find(dwarf::DW_AT_name), "");
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if (!Name.empty())
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VariableLoc.insert({Name, {LT, File, Line}});
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}
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}
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}
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// Returns the pair of file name and line number describing location of data
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// object (variable, array, etc) definition.
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template <class ELFT>
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Optional<std::pair<std::string, unsigned>>
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ObjFile<ELFT>::getVariableLoc(StringRef Name) {
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llvm::call_once(InitDwarfLine, [this]() { initializeDwarf(); });
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// Return if we have no debug information about data object.
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auto It = VariableLoc.find(Name);
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if (It == VariableLoc.end())
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return None;
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// Take file name string from line table.
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std::string FileName;
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if (!It->second.LT->getFileNameByIndex(
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It->second.File, nullptr,
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DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, FileName))
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return None;
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return std::make_pair(FileName, It->second.Line);
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}
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// Returns source line information for a given offset
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// using DWARF debug info.
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template <class ELFT>
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Optional<DILineInfo> ObjFile<ELFT>::getDILineInfo(InputSectionBase *S,
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uint64_t Offset) {
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llvm::call_once(InitDwarfLine, [this]() { initializeDwarf(); });
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// Use fake address calcuated by adding section file offset and offset in
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// section. See comments for ObjectInfo class.
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DILineInfo Info;
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for (const llvm::DWARFDebugLine::LineTable *LT : LineTables)
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if (LT->getFileLineInfoForAddress(
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S->getOffsetInFile() + Offset, nullptr,
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DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, Info))
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return Info;
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return None;
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}
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// Returns source line information for a given offset using DWARF debug info.
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template <class ELFT>
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std::string ObjFile<ELFT>::getLineInfo(InputSectionBase *S, uint64_t Offset) {
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if (Optional<DILineInfo> Info = getDILineInfo(S, Offset))
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return Info->FileName + ":" + std::to_string(Info->Line);
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return "";
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}
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// Returns "<internal>", "foo.a(bar.o)" or "baz.o".
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std::string lld::toString(const InputFile *F) {
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if (!F)
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return "<internal>";
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if (F->ToStringCache.empty()) {
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if (F->ArchiveName.empty())
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F->ToStringCache = F->getName();
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else
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F->ToStringCache = (F->ArchiveName + "(" + F->getName() + ")").str();
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}
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return F->ToStringCache;
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}
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template <class ELFT>
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ELFFileBase<ELFT>::ELFFileBase(Kind K, MemoryBufferRef MB) : InputFile(K, MB) {
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if (ELFT::TargetEndianness == support::little)
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EKind = ELFT::Is64Bits ? ELF64LEKind : ELF32LEKind;
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else
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EKind = ELFT::Is64Bits ? ELF64BEKind : ELF32BEKind;
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EMachine = getObj().getHeader()->e_machine;
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OSABI = getObj().getHeader()->e_ident[llvm::ELF::EI_OSABI];
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}
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template <class ELFT>
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typename ELFT::SymRange ELFFileBase<ELFT>::getGlobalELFSyms() {
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return makeArrayRef(ELFSyms.begin() + FirstGlobal, ELFSyms.end());
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}
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template <class ELFT>
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uint32_t ELFFileBase<ELFT>::getSectionIndex(const Elf_Sym &Sym) const {
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return CHECK(getObj().getSectionIndex(&Sym, ELFSyms, SymtabSHNDX), this);
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}
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template <class ELFT>
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void ELFFileBase<ELFT>::initSymtab(ArrayRef<Elf_Shdr> Sections,
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const Elf_Shdr *Symtab) {
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FirstGlobal = Symtab->sh_info;
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ELFSyms = CHECK(getObj().symbols(Symtab), this);
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if (FirstGlobal == 0 || FirstGlobal > ELFSyms.size())
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fatal(toString(this) + ": invalid sh_info in symbol table");
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StringTable =
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CHECK(getObj().getStringTableForSymtab(*Symtab, Sections), this);
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}
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template <class ELFT>
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ObjFile<ELFT>::ObjFile(MemoryBufferRef M, StringRef ArchiveName)
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: ELFFileBase<ELFT>(Base::ObjKind, M) {
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this->ArchiveName = ArchiveName;
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}
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template <class ELFT> ArrayRef<Symbol *> ObjFile<ELFT>::getLocalSymbols() {
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if (this->Symbols.empty())
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return {};
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return makeArrayRef(this->Symbols).slice(1, this->FirstGlobal - 1);
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}
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template <class ELFT> ArrayRef<Symbol *> ObjFile<ELFT>::getGlobalSymbols() {
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return makeArrayRef(this->Symbols).slice(this->FirstGlobal);
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}
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template <class ELFT>
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void ObjFile<ELFT>::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
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// Read section and symbol tables.
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initializeSections(ComdatGroups);
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initializeSymbols();
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}
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// Sections with SHT_GROUP and comdat bits define comdat section groups.
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// They are identified and deduplicated by group name. This function
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// returns a group name.
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template <class ELFT>
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StringRef ObjFile<ELFT>::getShtGroupSignature(ArrayRef<Elf_Shdr> Sections,
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const Elf_Shdr &Sec) {
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// Group signatures are stored as symbol names in object files.
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// sh_info contains a symbol index, so we fetch a symbol and read its name.
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if (this->ELFSyms.empty())
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this->initSymtab(
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Sections, CHECK(object::getSection<ELFT>(Sections, Sec.sh_link), this));
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const Elf_Sym *Sym =
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CHECK(object::getSymbol<ELFT>(this->ELFSyms, Sec.sh_info), this);
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StringRef Signature = CHECK(Sym->getName(this->StringTable), this);
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// As a special case, if a symbol is a section symbol and has no name,
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// we use a section name as a signature.
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//
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// Such SHT_GROUP sections are invalid from the perspective of the ELF
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// standard, but GNU gold 1.14 (the newest version as of July 2017) or
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// older produce such sections as outputs for the -r option, so we need
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// a bug-compatibility.
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if (Signature.empty() && Sym->getType() == STT_SECTION)
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return getSectionName(Sec);
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return Signature;
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}
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template <class ELFT>
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ArrayRef<typename ObjFile<ELFT>::Elf_Word>
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ObjFile<ELFT>::getShtGroupEntries(const Elf_Shdr &Sec) {
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const ELFFile<ELFT> &Obj = this->getObj();
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ArrayRef<Elf_Word> Entries =
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CHECK(Obj.template getSectionContentsAsArray<Elf_Word>(&Sec), this);
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if (Entries.empty() || Entries[0] != GRP_COMDAT)
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fatal(toString(this) + ": unsupported SHT_GROUP format");
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return Entries.slice(1);
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}
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template <class ELFT> bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
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// On a regular link we don't merge sections if -O0 (default is -O1). This
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// sometimes makes the linker significantly faster, although the output will
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// be bigger.
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//
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// Doing the same for -r would create a problem as it would combine sections
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// with different sh_entsize. One option would be to just copy every SHF_MERGE
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// section as is to the output. While this would produce a valid ELF file with
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// usable SHF_MERGE sections, tools like (llvm-)?dwarfdump get confused when
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// they see two .debug_str. We could have separate logic for combining
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// SHF_MERGE sections based both on their name and sh_entsize, but that seems
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// to be more trouble than it is worth. Instead, we just use the regular (-O1)
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// logic for -r.
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if (Config->Optimize == 0 && !Config->Relocatable)
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return false;
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// A mergeable section with size 0 is useless because they don't have
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// any data to merge. A mergeable string section with size 0 can be
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// argued as invalid because it doesn't end with a null character.
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// We'll avoid a mess by handling them as if they were non-mergeable.
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if (Sec.sh_size == 0)
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return false;
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// Check for sh_entsize. The ELF spec is not clear about the zero
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// sh_entsize. It says that "the member [sh_entsize] contains 0 if
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// the section does not hold a table of fixed-size entries". We know
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// that Rust 1.13 produces a string mergeable section with a zero
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// sh_entsize. Here we just accept it rather than being picky about it.
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uint64_t EntSize = Sec.sh_entsize;
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if (EntSize == 0)
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return false;
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if (Sec.sh_size % EntSize)
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fatal(toString(this) +
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": SHF_MERGE section size must be a multiple of sh_entsize");
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uint64_t Flags = Sec.sh_flags;
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if (!(Flags & SHF_MERGE))
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return false;
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if (Flags & SHF_WRITE)
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fatal(toString(this) + ": writable SHF_MERGE section is not supported");
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return true;
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}
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template <class ELFT>
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void ObjFile<ELFT>::initializeSections(
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DenseSet<CachedHashStringRef> &ComdatGroups) {
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const ELFFile<ELFT> &Obj = this->getObj();
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ArrayRef<Elf_Shdr> ObjSections = CHECK(this->getObj().sections(), this);
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uint64_t Size = ObjSections.size();
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this->Sections.resize(Size);
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this->SectionStringTable =
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CHECK(Obj.getSectionStringTable(ObjSections), this);
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for (size_t I = 0, E = ObjSections.size(); I < E; I++) {
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if (this->Sections[I] == &InputSection::Discarded)
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continue;
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const Elf_Shdr &Sec = ObjSections[I];
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// SHF_EXCLUDE'ed sections are discarded by the linker. However,
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// if -r is given, we'll let the final link discard such sections.
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// This is compatible with GNU.
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if ((Sec.sh_flags & SHF_EXCLUDE) && !Config->Relocatable) {
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this->Sections[I] = &InputSection::Discarded;
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continue;
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}
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switch (Sec.sh_type) {
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case SHT_GROUP: {
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// De-duplicate section groups by their signatures.
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StringRef Signature = getShtGroupSignature(ObjSections, Sec);
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bool IsNew = ComdatGroups.insert(CachedHashStringRef(Signature)).second;
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this->Sections[I] = &InputSection::Discarded;
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// If it is a new section group, we want to keep group members.
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// Group leader sections, which contain indices of group members, are
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// discarded because they are useless beyond this point. The only
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// exception is the -r option because in order to produce re-linkable
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// object files, we want to pass through basically everything.
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if (IsNew) {
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if (Config->Relocatable)
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this->Sections[I] = createInputSection(Sec);
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continue;
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}
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// Otherwise, discard group members.
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for (uint32_t SecIndex : getShtGroupEntries(Sec)) {
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if (SecIndex >= Size)
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fatal(toString(this) +
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": invalid section index in group: " + Twine(SecIndex));
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this->Sections[SecIndex] = &InputSection::Discarded;
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}
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break;
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}
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case SHT_SYMTAB:
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this->initSymtab(ObjSections, &Sec);
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break;
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case SHT_SYMTAB_SHNDX:
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this->SymtabSHNDX = CHECK(Obj.getSHNDXTable(Sec, ObjSections), this);
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break;
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case SHT_STRTAB:
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case SHT_NULL:
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break;
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default:
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this->Sections[I] = createInputSection(Sec);
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}
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// .ARM.exidx sections have a reverse dependency on the InputSection they
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// have a SHF_LINK_ORDER dependency, this is identified by the sh_link.
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if (Sec.sh_flags & SHF_LINK_ORDER) {
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if (Sec.sh_link >= this->Sections.size())
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fatal(toString(this) +
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": invalid sh_link index: " + Twine(Sec.sh_link));
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InputSectionBase *LinkSec = this->Sections[Sec.sh_link];
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InputSection *IS = cast<InputSection>(this->Sections[I]);
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LinkSec->DependentSections.push_back(IS);
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if (!isa<InputSection>(LinkSec))
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error("a section " + IS->Name +
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" with SHF_LINK_ORDER should not refer a non-regular "
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"section: " +
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toString(LinkSec));
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}
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}
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}
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// The ARM support in lld makes some use of instructions that are not available
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// on all ARM architectures. Namely:
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// - Use of BLX instruction for interworking between ARM and Thumb state.
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// - Use of the extended Thumb branch encoding in relocation.
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// - Use of the MOVT/MOVW instructions in Thumb Thunks.
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// The ARM Attributes section contains information about the architecture chosen
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// at compile time. We follow the convention that if at least one input object
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// is compiled with an architecture that supports these features then lld is
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// permitted to use them.
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static void updateSupportedARMFeatures(const ARMAttributeParser &Attributes) {
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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;
|
|
}
|
|
}
|
|
|
|
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);
|
|
// 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 (InX::ARMAttributes == nullptr) {
|
|
InX::ARMAttributes = make<InputSection>(*this, Sec, Name);
|
|
return InX::ARMAttributes;
|
|
}
|
|
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)
|
|
return make<InputSection>(*this, Sec, Name);
|
|
|
|
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(this->getObj().relas(&Sec), this);
|
|
Target->FirstRelocation = Rels.begin();
|
|
Target->NumRelocations = Rels.size();
|
|
Target->AreRelocsRela = true;
|
|
} else {
|
|
ArrayRef<Elf_Rel> Rels = CHECK(this->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;
|
|
|
|
// Split stacks is a feature to support a discontiguous stack. At least
|
|
// as of 2017, it seems that the feature is not being used widely.
|
|
// Only GNU gold supports that. We don't. For the details about that,
|
|
// see https://gcc.gnu.org/wiki/SplitStacks
|
|
if (Name == ".note.GNU-split-stack") {
|
|
error(toString(this) +
|
|
": object file compiled with -fsplit-stack is not supported");
|
|
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.startswith(".gnu.linkonce."))
|
|
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(this->getObj().getSectionName(&Sec, SectionStringTable), this);
|
|
}
|
|
|
|
template <class ELFT> void ObjFile<ELFT>::initializeSymbols() {
|
|
this->Symbols.reserve(this->ELFSyms.size());
|
|
for (const Elf_Sym &Sym : this->ELFSyms)
|
|
this->Symbols.push_back(createSymbol(&Sym));
|
|
}
|
|
|
|
template <class ELFT> Symbol *ObjFile<ELFT>::createSymbol(const Elf_Sym *Sym) {
|
|
int Binding = Sym->getBinding();
|
|
|
|
uint32_t SecIdx = this->getSectionIndex(*Sym);
|
|
if (SecIdx >= this->Sections.size())
|
|
fatal(toString(this) + ": invalid section index: " + Twine(SecIdx));
|
|
|
|
InputSectionBase *Sec = this->Sections[SecIdx];
|
|
uint8_t StOther = Sym->st_other;
|
|
uint8_t Type = Sym->getType();
|
|
uint64_t Value = Sym->st_value;
|
|
uint64_t Size = Sym->st_size;
|
|
|
|
if (Binding == STB_LOCAL) {
|
|
if (Sym->getType() == STT_FILE)
|
|
SourceFile = CHECK(Sym->getName(this->StringTable), this);
|
|
|
|
if (this->StringTable.size() <= Sym->st_name)
|
|
fatal(toString(this) + ": invalid symbol name offset");
|
|
|
|
StringRefZ Name = this->StringTable.data() + Sym->st_name;
|
|
if (Sym->st_shndx == SHN_UNDEF)
|
|
return make<Undefined>(this, Name, Binding, StOther, Type);
|
|
|
|
return make<Defined>(this, Name, Binding, StOther, Type, Value, Size, Sec);
|
|
}
|
|
|
|
StringRef Name = CHECK(Sym->getName(this->StringTable), this);
|
|
|
|
switch (Sym->st_shndx) {
|
|
case SHN_UNDEF:
|
|
return Symtab->addUndefined<ELFT>(Name, Binding, StOther, Type,
|
|
/*CanOmitFromDynSym=*/false, this);
|
|
case SHN_COMMON:
|
|
if (Value == 0 || Value >= UINT32_MAX)
|
|
fatal(toString(this) + ": common symbol '" + Name +
|
|
"' has invalid alignment: " + Twine(Value));
|
|
return Symtab->addCommon(Name, Size, Value, Binding, StOther, Type, *this);
|
|
}
|
|
|
|
switch (Binding) {
|
|
default:
|
|
fatal(toString(this) + ": unexpected binding: " + Twine(Binding));
|
|
case STB_GLOBAL:
|
|
case STB_WEAK:
|
|
case STB_GNU_UNIQUE:
|
|
if (Sec == &InputSection::Discarded)
|
|
return Symtab->addUndefined<ELFT>(Name, Binding, StOther, Type,
|
|
/*CanOmitFromDynSym=*/false, this);
|
|
return Symtab->addRegular(Name, StOther, Type, Value, Size, Binding, Sec,
|
|
this);
|
|
}
|
|
}
|
|
|
|
ArchiveFile::ArchiveFile(std::unique_ptr<Archive> &&File)
|
|
: InputFile(ArchiveKind, File->getMemoryBufferRef()),
|
|
File(std::move(File)) {}
|
|
|
|
template <class ELFT> void ArchiveFile::parse() {
|
|
for (const Archive::Symbol &Sym : File->symbols())
|
|
Symtab->addLazyArchive<ELFT>(Sym.getName(), *this, Sym);
|
|
}
|
|
|
|
// Returns a buffer pointing to a member file containing a given symbol.
|
|
std::pair<MemoryBufferRef, uint64_t>
|
|
ArchiveFile::getMember(const Archive::Symbol *Sym) {
|
|
Archive::Child C =
|
|
CHECK(Sym->getMember(), toString(this) +
|
|
": could not get the member for symbol " +
|
|
Sym->getName());
|
|
|
|
if (!Seen.insert(C.getChildOffset()).second)
|
|
return {MemoryBufferRef(), 0};
|
|
|
|
MemoryBufferRef Ret =
|
|
CHECK(C.getMemoryBufferRef(),
|
|
toString(this) +
|
|
": could not get the buffer for the member defining symbol " +
|
|
Sym->getName());
|
|
|
|
if (C.getParent()->isThin() && Tar)
|
|
Tar->append(relativeToRoot(CHECK(C.getFullName(), this)), Ret.getBuffer());
|
|
if (C.getParent()->isThin())
|
|
return {Ret, 0};
|
|
return {Ret, C.getChildOffset()};
|
|
}
|
|
|
|
template <class ELFT>
|
|
SharedFile<ELFT>::SharedFile(MemoryBufferRef M, StringRef DefaultSoName)
|
|
: ELFFileBase<ELFT>(Base::SharedKind, M), SoName(DefaultSoName),
|
|
IsNeeded(!Config->AsNeeded) {}
|
|
|
|
// Partially parse the shared object file so that we can call
|
|
// getSoName on this object.
|
|
template <class ELFT> void SharedFile<ELFT>::parseSoName() {
|
|
const Elf_Shdr *DynamicSec = nullptr;
|
|
const ELFFile<ELFT> Obj = this->getObj();
|
|
ArrayRef<Elf_Shdr> Sections = CHECK(Obj.sections(), this);
|
|
|
|
// 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_DYNSYM:
|
|
this->initSymtab(Sections, &Sec);
|
|
break;
|
|
case SHT_DYNAMIC:
|
|
DynamicSec = &Sec;
|
|
break;
|
|
case SHT_SYMTAB_SHNDX:
|
|
this->SymtabSHNDX = CHECK(Obj.getSHNDXTable(Sec, Sections), this);
|
|
break;
|
|
case SHT_GNU_versym:
|
|
this->VersymSec = &Sec;
|
|
break;
|
|
case SHT_GNU_verdef:
|
|
this->VerdefSec = &Sec;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (this->VersymSec && this->ELFSyms.empty())
|
|
error("SHT_GNU_versym should be associated with symbol table");
|
|
|
|
// Search for a DT_SONAME tag to initialize this->SoName.
|
|
if (!DynamicSec)
|
|
return;
|
|
ArrayRef<Elf_Dyn> Arr =
|
|
CHECK(Obj.template getSectionContentsAsArray<Elf_Dyn>(DynamicSec), this);
|
|
for (const Elf_Dyn &Dyn : Arr) {
|
|
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;
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Parses ".gnu.version" section which is a parallel array for the symbol table.
|
|
// If a given file doesn't have ".gnu.version" section, returns VER_NDX_GLOBAL.
|
|
template <class ELFT> std::vector<uint32_t> SharedFile<ELFT>::parseVersyms() {
|
|
size_t Size = this->ELFSyms.size() - this->FirstGlobal;
|
|
if (!VersymSec)
|
|
return std::vector<uint32_t>(Size, VER_NDX_GLOBAL);
|
|
|
|
const char *Base = this->MB.getBuffer().data();
|
|
const Elf_Versym *Versym =
|
|
reinterpret_cast<const Elf_Versym *>(Base + VersymSec->sh_offset) +
|
|
this->FirstGlobal;
|
|
|
|
std::vector<uint32_t> Ret(Size);
|
|
for (size_t I = 0; I < Size; ++I)
|
|
Ret[I] = Versym[I].vs_index;
|
|
return Ret;
|
|
}
|
|
|
|
// Parse the version definitions in the object file if present. Returns 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 <class ELFT>
|
|
std::vector<const typename ELFT::Verdef *> SharedFile<ELFT>::parseVerdefs() {
|
|
if (!VerdefSec)
|
|
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 = VerdefSec->sh_info;
|
|
std::vector<const Elf_Verdef *> 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 char *Base = this->MB.getBuffer().data();
|
|
const char *Verdef = Base + VerdefSec->sh_offset;
|
|
for (unsigned I = 0; I != VerdefCount; ++I) {
|
|
auto *CurVerdef = reinterpret_cast<const Elf_Verdef *>(Verdef);
|
|
Verdef += CurVerdef->vd_next;
|
|
unsigned VerdefIndex = CurVerdef->vd_ndx;
|
|
if (Verdefs.size() <= VerdefIndex)
|
|
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 <class ELFT>
|
|
uint32_t SharedFile<ELFT>::getAlignment(ArrayRef<Elf_Shdr> Sections,
|
|
const Elf_Sym &Sym) {
|
|
uint64_t Ret = 1;
|
|
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);
|
|
|
|
if (Ret > UINT32_MAX)
|
|
error(toString(this) + ": alignment too large: " +
|
|
CHECK(Sym.getName(this->StringTable), this));
|
|
return Ret;
|
|
}
|
|
|
|
// Fully parse the shared object file. This must be called after parseSoName().
|
|
//
|
|
// 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<ELFT>::parseRest() {
|
|
Verdefs = parseVerdefs(); // parse .gnu.version_d
|
|
std::vector<uint32_t> Versyms = parseVersyms(); // parse .gnu.version
|
|
ArrayRef<Elf_Shdr> Sections = CHECK(this->getObj().sections(), this);
|
|
|
|
// Add symbols to the symbol table.
|
|
ArrayRef<Elf_Sym> Syms = this->getGlobalELFSyms();
|
|
for (size_t I = 0; I < Syms.size(); ++I) {
|
|
const Elf_Sym &Sym = Syms[I];
|
|
|
|
StringRef Name = CHECK(Sym.getName(this->StringTable), this);
|
|
if (Sym.isUndefined()) {
|
|
Symbol *S = Symtab->addUndefined<ELFT>(Name, Sym.getBinding(),
|
|
Sym.st_other, Sym.getType(),
|
|
/*CanOmitFromDynSym=*/false, this);
|
|
S->ExportDynamic = true;
|
|
continue;
|
|
}
|
|
|
|
// 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.
|
|
if (Sym.getBinding() == STB_LOCAL) {
|
|
warn("found local symbol '" + Name +
|
|
"' in global part of symbol table in file " + toString(this));
|
|
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;
|
|
|
|
uint64_t Alignment = getAlignment(Sections, Sym);
|
|
if (!(Versyms[I] & VERSYM_HIDDEN))
|
|
Symtab->addShared(Name, *this, Sym, 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() + Verdefs[Idx]->getAux()->vda_name;
|
|
Name = Saver.save(Name + "@" + VerName);
|
|
Symtab->addShared(Name, *this, Sym, 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::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::ppc:
|
|
return EM_PPC;
|
|
case Triple::ppc64:
|
|
return EM_PPC64;
|
|
case Triple::x86:
|
|
return T.isOSIAMCU() ? EM_IAMCU : EM_386;
|
|
case Triple::x86_64:
|
|
return EM_X86_64;
|
|
default:
|
|
fatal(Path + ": could not infer e_machine from bitcode target triple " +
|
|
T.str());
|
|
}
|
|
}
|
|
|
|
BitcodeFile::BitcodeFile(MemoryBufferRef MB, StringRef ArchiveName,
|
|
uint64_t OffsetInArchive)
|
|
: InputFile(BitcodeKind, MB) {
|
|
this->ArchiveName = ArchiveName;
|
|
|
|
// Here we pass a new MemoryBufferRef which is identified by ArchiveName
|
|
// (the fully resolved path of the archive) + member name + offset of the
|
|
// member in the archive.
|
|
// ThinLTO uses the MemoryBufferRef identifier to access its internal
|
|
// data structures and 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).
|
|
MemoryBufferRef MBRef(MB.getBuffer(),
|
|
Saver.save(ArchiveName + MB.getBufferIdentifier() +
|
|
utostr(OffsetInArchive)));
|
|
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 NameRef = Saver.save(ObjSym.getName());
|
|
uint32_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 (C != -1 && !KeptComdats[C])
|
|
return Symtab->addUndefined<ELFT>(NameRef, Binding, Visibility, Type,
|
|
CanOmitFromDynSym, &F);
|
|
|
|
if (ObjSym.isUndefined())
|
|
return Symtab->addUndefined<ELFT>(NameRef, Binding, Visibility, Type,
|
|
CanOmitFromDynSym, &F);
|
|
|
|
if (ObjSym.isCommon())
|
|
return Symtab->addCommon(NameRef, ObjSym.getCommonSize(),
|
|
ObjSym.getCommonAlignment(), Binding, Visibility,
|
|
STT_OBJECT, F);
|
|
|
|
return Symtab->addBitcode(NameRef, Binding, Visibility, Type,
|
|
CanOmitFromDynSym, F);
|
|
}
|
|
|
|
template <class ELFT>
|
|
void BitcodeFile::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
|
|
std::vector<bool> KeptComdats;
|
|
for (StringRef S : Obj->getComdatTable())
|
|
KeptComdats.push_back(ComdatGroups.insert(CachedHashStringRef(S)).second);
|
|
|
|
for (const lto::InputFile::Symbol &ObjSym : Obj->symbols())
|
|
Symbols.push_back(createBitcodeSymbol<ELFT>(KeptComdats, ObjSym, *this));
|
|
}
|
|
|
|
static ELFKind getELFKind(MemoryBufferRef MB) {
|
|
unsigned char Size;
|
|
unsigned char Endian;
|
|
std::tie(Size, Endian) = getElfArchType(MB.getBuffer());
|
|
|
|
if (Endian != ELFDATA2LSB && Endian != ELFDATA2MSB)
|
|
fatal(MB.getBufferIdentifier() + ": invalid data encoding");
|
|
if (Size != ELFCLASS32 && Size != ELFCLASS64)
|
|
fatal(MB.getBufferIdentifier() + ": invalid file class");
|
|
|
|
size_t BufSize = MB.getBuffer().size();
|
|
if ((Size == ELFCLASS32 && BufSize < sizeof(Elf32_Ehdr)) ||
|
|
(Size == ELFCLASS64 && BufSize < sizeof(Elf64_Ehdr)))
|
|
fatal(MB.getBufferIdentifier() + ": file is too short");
|
|
|
|
if (Size == ELFCLASS32)
|
|
return (Endian == ELFDATA2LSB) ? ELF32LEKind : ELF32BEKind;
|
|
return (Endian == ELFDATA2LSB) ? ELF64LEKind : ELF64BEKind;
|
|
}
|
|
|
|
void BinaryFile::parse() {
|
|
ArrayRef<uint8_t> Data = toArrayRef(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->addRegular(Saver.save(S + "_start"), STV_DEFAULT, STT_OBJECT, 0, 0,
|
|
STB_GLOBAL, Section, nullptr);
|
|
Symtab->addRegular(Saver.save(S + "_end"), STV_DEFAULT, STT_OBJECT,
|
|
Data.size(), 0, STB_GLOBAL, Section, nullptr);
|
|
Symtab->addRegular(Saver.save(S + "_size"), STV_DEFAULT, STT_OBJECT,
|
|
Data.size(), 0, STB_GLOBAL, nullptr, nullptr);
|
|
}
|
|
|
|
static bool isBitcode(MemoryBufferRef MB) {
|
|
using namespace sys::fs;
|
|
return identify_magic(MB.getBuffer()) == file_magic::bitcode;
|
|
}
|
|
|
|
InputFile *elf::createObjectFile(MemoryBufferRef MB, StringRef ArchiveName,
|
|
uint64_t OffsetInArchive) {
|
|
if (isBitcode(MB))
|
|
return make<BitcodeFile>(MB, ArchiveName, OffsetInArchive);
|
|
|
|
switch (getELFKind(MB)) {
|
|
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");
|
|
}
|
|
}
|
|
|
|
InputFile *elf::createSharedFile(MemoryBufferRef MB, StringRef DefaultSoName) {
|
|
switch (getELFKind(MB)) {
|
|
case ELF32LEKind:
|
|
return make<SharedFile<ELF32LE>>(MB, DefaultSoName);
|
|
case ELF32BEKind:
|
|
return make<SharedFile<ELF32BE>>(MB, DefaultSoName);
|
|
case ELF64LEKind:
|
|
return make<SharedFile<ELF64LE>>(MB, DefaultSoName);
|
|
case ELF64BEKind:
|
|
return make<SharedFile<ELF64BE>>(MB, DefaultSoName);
|
|
default:
|
|
llvm_unreachable("getELFKind");
|
|
}
|
|
}
|
|
|
|
MemoryBufferRef LazyObjFile::getBuffer() {
|
|
if (Seen)
|
|
return MemoryBufferRef();
|
|
Seen = true;
|
|
return MB;
|
|
}
|
|
|
|
InputFile *LazyObjFile::fetch() {
|
|
MemoryBufferRef MBRef = getBuffer();
|
|
if (MBRef.getBuffer().empty())
|
|
return nullptr;
|
|
return createObjectFile(MBRef, ArchiveName, OffsetInArchive);
|
|
}
|
|
|
|
template <class ELFT> void LazyObjFile::parse() {
|
|
// 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())
|
|
Symtab->addLazyObject<ELFT>(Saver.save(Sym.getName()), *this);
|
|
return;
|
|
}
|
|
|
|
switch (getELFKind(this->MB)) {
|
|
case ELF32LEKind:
|
|
addElfSymbols<ELF32LE>();
|
|
return;
|
|
case ELF32BEKind:
|
|
addElfSymbols<ELF32BE>();
|
|
return;
|
|
case ELF64LEKind:
|
|
addElfSymbols<ELF64LE>();
|
|
return;
|
|
case ELF64BEKind:
|
|
addElfSymbols<ELF64BE>();
|
|
return;
|
|
default:
|
|
llvm_unreachable("getELFKind");
|
|
}
|
|
}
|
|
|
|
template <class ELFT> void LazyObjFile::addElfSymbols() {
|
|
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;
|
|
|
|
typename ELFT::SymRange Syms = CHECK(Obj.symbols(&Sec), this);
|
|
uint32_t FirstGlobal = Sec.sh_info;
|
|
StringRef StringTable =
|
|
CHECK(Obj.getStringTableForSymtab(Sec, Sections), this);
|
|
|
|
for (const typename ELFT::Sym &Sym : Syms.slice(FirstGlobal))
|
|
if (Sym.st_shndx != SHN_UNDEF)
|
|
Symtab->addLazyObject<ELFT>(CHECK(Sym.getName(StringTable), this),
|
|
*this);
|
|
return;
|
|
}
|
|
}
|
|
|
|
// This is for --just-symbols.
|
|
//
|
|
// This option 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 use program's symbols.
|
|
//
|
|
// What we are doing here is to read defined symbols from a given ELF
|
|
// file and add them as absolute symbols.
|
|
template <class ELFT> void elf::readJustSymbolsFile(MemoryBufferRef MB) {
|
|
typedef typename ELFT::Shdr Elf_Shdr;
|
|
typedef typename ELFT::Sym Elf_Sym;
|
|
typedef typename ELFT::SymRange Elf_Sym_Range;
|
|
|
|
StringRef ObjName = MB.getBufferIdentifier();
|
|
ELFFile<ELFT> Obj = check(ELFFile<ELFT>::create(MB.getBuffer()));
|
|
ArrayRef<Elf_Shdr> Sections = CHECK(Obj.sections(), ObjName);
|
|
|
|
for (const Elf_Shdr &Sec : Sections) {
|
|
if (Sec.sh_type != SHT_SYMTAB)
|
|
continue;
|
|
|
|
Elf_Sym_Range Syms = CHECK(Obj.symbols(&Sec), ObjName);
|
|
uint32_t FirstGlobal = Sec.sh_info;
|
|
StringRef StringTable =
|
|
CHECK(Obj.getStringTableForSymtab(Sec, Sections), ObjName);
|
|
|
|
for (const Elf_Sym &Sym : Syms.slice(FirstGlobal))
|
|
if (Sym.st_shndx != SHN_UNDEF)
|
|
Symtab->addRegular(CHECK(Sym.getName(StringTable), ObjName),
|
|
Sym.st_other, Sym.getType(), Sym.st_value,
|
|
Sym.st_size, Sym.getBinding(), nullptr, nullptr);
|
|
return;
|
|
}
|
|
}
|
|
|
|
template void ArchiveFile::parse<ELF32LE>();
|
|
template void ArchiveFile::parse<ELF32BE>();
|
|
template void ArchiveFile::parse<ELF64LE>();
|
|
template void ArchiveFile::parse<ELF64BE>();
|
|
|
|
template void BitcodeFile::parse<ELF32LE>(DenseSet<CachedHashStringRef> &);
|
|
template void BitcodeFile::parse<ELF32BE>(DenseSet<CachedHashStringRef> &);
|
|
template void BitcodeFile::parse<ELF64LE>(DenseSet<CachedHashStringRef> &);
|
|
template void BitcodeFile::parse<ELF64BE>(DenseSet<CachedHashStringRef> &);
|
|
|
|
template void LazyObjFile::parse<ELF32LE>();
|
|
template void LazyObjFile::parse<ELF32BE>();
|
|
template void LazyObjFile::parse<ELF64LE>();
|
|
template void LazyObjFile::parse<ELF64BE>();
|
|
|
|
template class elf::ELFFileBase<ELF32LE>;
|
|
template class elf::ELFFileBase<ELF32BE>;
|
|
template class elf::ELFFileBase<ELF64LE>;
|
|
template class elf::ELFFileBase<ELF64BE>;
|
|
|
|
template class elf::ObjFile<ELF32LE>;
|
|
template class elf::ObjFile<ELF32BE>;
|
|
template class elf::ObjFile<ELF64LE>;
|
|
template class elf::ObjFile<ELF64BE>;
|
|
|
|
template class elf::SharedFile<ELF32LE>;
|
|
template class elf::SharedFile<ELF32BE>;
|
|
template class elf::SharedFile<ELF64LE>;
|
|
template class elf::SharedFile<ELF64BE>;
|
|
|
|
template void elf::readJustSymbolsFile<ELF32LE>(MemoryBufferRef);
|
|
template void elf::readJustSymbolsFile<ELF32BE>(MemoryBufferRef);
|
|
template void elf::readJustSymbolsFile<ELF64LE>(MemoryBufferRef);
|
|
template void elf::readJustSymbolsFile<ELF64BE>(MemoryBufferRef);
|