forked from OSchip/llvm-project
1011 lines
36 KiB
C++
1011 lines
36 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 "Error.h"
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#include "InputSection.h"
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#include "LinkerScript.h"
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#include "Memory.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 "llvm/ADT/STLExtras.h"
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#include "llvm/Bitcode/BitcodeReader.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/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::fs;
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using namespace lld;
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using namespace lld::elf;
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TarWriter *elf::Tar;
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namespace {
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// In ELF object file all section addresses are zero. If we have multiple
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// .text sections (when using -ffunction-section or comdat group) then
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// LLVM DWARF parser will not be able to parse .debug_line correctly, unless
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// we assign each section some unique address. This callback method assigns
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// each section an address equal to its offset in ELF object file.
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class ObjectInfo : public LoadedObjectInfo {
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public:
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uint64_t getSectionLoadAddress(const object::SectionRef &Sec) const override {
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return static_cast<const ELFSectionRef &>(Sec).getOffset();
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}
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std::unique_ptr<LoadedObjectInfo> clone() const override {
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return std::unique_ptr<LoadedObjectInfo>();
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}
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};
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}
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Optional<MemoryBufferRef> elf::readFile(StringRef 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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template <class ELFT> void elf::ObjectFile<ELFT>::initializeDwarfLine() {
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std::unique_ptr<object::ObjectFile> Obj =
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check(object::ObjectFile::createObjectFile(this->MB),
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"createObjectFile failed");
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ObjectInfo ObjInfo;
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DWARFContextInMemory Dwarf(*Obj, &ObjInfo);
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DwarfLine.reset(new DWARFDebugLine(&Dwarf.getLineSection().Relocs));
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DataExtractor LineData(Dwarf.getLineSection().Data,
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ELFT::TargetEndianness == support::little,
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ELFT::Is64Bits ? 8 : 4);
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// The second parameter is offset in .debug_line section
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// for compilation unit (CU) of interest. We have only one
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// CU (object file), so offset is always 0.
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DwarfLine->getOrParseLineTable(LineData, 0);
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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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std::string elf::ObjectFile<ELFT>::getLineInfo(InputSectionBase *S,
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uint64_t Offset) {
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if (!DwarfLine)
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initializeDwarfLine();
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// The offset to CU is 0.
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const DWARFDebugLine::LineTable *Tbl = DwarfLine->getLineTable(0);
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if (!Tbl)
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return "";
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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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Tbl->getFileLineInfoForAddress(
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S->Offset + Offset, nullptr,
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DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, Info);
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if (Info.Line == 0)
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return "";
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return Info.FileName + ":" + std::to_string(Info.Line);
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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->ArchiveName.empty())
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return (F->ArchiveName + "(" + F->getName() + ")").str();
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return F->getName();
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}
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template <class ELFT> static ELFKind getELFKind() {
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if (ELFT::TargetEndianness == support::little)
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return ELFT::Is64Bits ? ELF64LEKind : ELF32LEKind;
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return ELFT::Is64Bits ? ELF64BEKind : ELF32BEKind;
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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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EKind = getELFKind<ELFT>();
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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>::getGlobalSymbols() {
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return makeArrayRef(Symbols.begin() + FirstNonLocal, Symbols.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, Symbols, SymtabSHNDX));
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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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FirstNonLocal = Symtab->sh_info;
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Symbols = check(getObj().symbols(Symtab));
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if (FirstNonLocal == 0 || FirstNonLocal > Symbols.size())
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fatal(toString(this) + ": invalid sh_info in symbol table");
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StringTable = check(getObj().getStringTableForSymtab(*Symtab, Sections));
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}
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template <class ELFT>
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elf::ObjectFile<ELFT>::ObjectFile(MemoryBufferRef M)
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: ELFFileBase<ELFT>(Base::ObjectKind, M) {}
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template <class ELFT>
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ArrayRef<SymbolBody *> elf::ObjectFile<ELFT>::getNonLocalSymbols() {
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return makeArrayRef(this->SymbolBodies).slice(this->FirstNonLocal);
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}
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template <class ELFT>
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ArrayRef<SymbolBody *> elf::ObjectFile<ELFT>::getLocalSymbols() {
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if (this->SymbolBodies.empty())
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return this->SymbolBodies;
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return makeArrayRef(this->SymbolBodies).slice(1, this->FirstNonLocal - 1);
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}
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template <class ELFT>
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ArrayRef<SymbolBody *> elf::ObjectFile<ELFT>::getSymbols() {
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if (this->SymbolBodies.empty())
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return this->SymbolBodies;
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return makeArrayRef(this->SymbolBodies).slice(1);
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}
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template <class ELFT>
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void elf::ObjectFile<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
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elf::ObjectFile<ELFT>::getShtGroupSignature(ArrayRef<Elf_Shdr> Sections,
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const Elf_Shdr &Sec) {
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if (this->Symbols.empty())
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this->initSymtab(Sections,
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check(object::getSection<ELFT>(Sections, Sec.sh_link)));
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const Elf_Sym *Sym =
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check(object::getSymbol<ELFT>(this->Symbols, Sec.sh_info));
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return check(Sym->getName(this->StringTable));
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}
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template <class ELFT>
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ArrayRef<typename elf::ObjectFile<ELFT>::Elf_Word>
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elf::ObjectFile<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));
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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>
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bool elf::ObjectFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
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// We don't merge sections if -O0 (default is -O1). This makes sometimes
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// the linker significantly faster, although the output will be bigger.
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if (Config->Optimize == 0)
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return false;
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// Do not merge sections if generating a relocatable object. It makes
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// the code simpler because we do not need to update relocation addends
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// to reflect changes introduced by merging. Instead of that we write
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// such "merge" sections into separate OutputSections and keep SHF_MERGE
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// / SHF_STRINGS flags and sh_entsize value to be able to perform merging
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// later during a final linking.
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if (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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// Don't try to merge if the alignment is larger than the sh_entsize and this
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// is not SHF_STRINGS.
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//
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// Since this is not a SHF_STRINGS, we would need to pad after every entity.
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// It would be equivalent for the producer of the .o to just set a larger
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// sh_entsize.
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if (Flags & SHF_STRINGS)
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return true;
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return Sec.sh_addralign <= EntSize;
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}
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template <class ELFT>
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void elf::ObjectFile<ELFT>::initializeSections(
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DenseSet<CachedHashStringRef> &ComdatGroups) {
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ArrayRef<Elf_Shdr> ObjSections = check(this->getObj().sections());
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const ELFFile<ELFT> &Obj = this->getObj();
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uint64_t Size = ObjSections.size();
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Sections.resize(Size);
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unsigned I = -1;
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StringRef SectionStringTable = check(Obj.getSectionStringTable(ObjSections));
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for (const Elf_Shdr &Sec : ObjSections) {
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++I;
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if (Sections[I] == &InputSection::Discarded)
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continue;
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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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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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Sections[I] = &InputSection::Discarded;
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if (ComdatGroups.insert(CachedHashStringRef(
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getShtGroupSignature(ObjSections, Sec)))
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.second)
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continue;
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for (uint32_t SecIndex : getShtGroupEntries(Sec)) {
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if (SecIndex >= Size)
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fatal(toString(this) + ": invalid section index in group: " +
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Twine(SecIndex));
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Sections[SecIndex] = &InputSection::Discarded;
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}
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break;
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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));
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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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Sections[I] = createInputSection(Sec, SectionStringTable);
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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 >= Sections.size())
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fatal(toString(this) + ": invalid sh_link index: " +
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Twine(Sec.sh_link));
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Sections[Sec.sh_link]->DependentSections.push_back(Sections[I]);
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}
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}
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}
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template <class ELFT>
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InputSectionBase *elf::ObjectFile<ELFT>::getRelocTarget(const Elf_Shdr &Sec) {
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uint32_t Idx = Sec.sh_info;
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if (Idx >= Sections.size())
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fatal(toString(this) + ": invalid relocated section index: " + Twine(Idx));
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InputSectionBase *Target = Sections[Idx];
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// Strictly speaking, a relocation section must be included in the
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// group of the section it relocates. However, LLVM 3.3 and earlier
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// would fail to do so, so we gracefully handle that case.
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if (Target == &InputSection::Discarded)
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return nullptr;
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if (!Target)
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fatal(toString(this) + ": unsupported relocation reference");
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return Target;
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}
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template <class ELFT>
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InputSectionBase *
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elf::ObjectFile<ELFT>::createInputSection(const Elf_Shdr &Sec,
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StringRef SectionStringTable) {
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StringRef Name =
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check(this->getObj().getSectionName(&Sec, SectionStringTable));
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switch (Sec.sh_type) {
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case SHT_ARM_ATTRIBUTES:
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// FIXME: ARM meta-data section. Retain the first attribute section
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// we see. The eglibc ARM dynamic loaders require the presence of an
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// attribute section for dlopen to work.
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// In a full implementation we would merge all attribute sections.
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if (In<ELFT>::ARMAttributes == nullptr) {
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In<ELFT>::ARMAttributes = make<InputSection>(this, &Sec, Name);
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return In<ELFT>::ARMAttributes;
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}
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return &InputSection::Discarded;
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case SHT_RELA:
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case SHT_REL: {
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// Find the relocation target section and associate this
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// section with it. Target can be discarded, for example
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// if it is a duplicated member of SHT_GROUP section, we
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// do not create or proccess relocatable sections then.
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InputSectionBase *Target = getRelocTarget(Sec);
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if (!Target)
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return nullptr;
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// This section contains relocation information.
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// If -r is given, we do not interpret or apply relocation
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// but just copy relocation sections to output.
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if (Config->Relocatable)
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return make<InputSection>(this, &Sec, Name);
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if (Target->FirstRelocation)
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fatal(toString(this) +
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": multiple relocation sections to one section are not supported");
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if (isa<MergeInputSection<ELFT>>(Target))
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fatal(toString(this) +
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": relocations pointing to SHF_MERGE are not supported");
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size_t NumRelocations;
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if (Sec.sh_type == SHT_RELA) {
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ArrayRef<Elf_Rela> Rels = check(this->getObj().relas(&Sec));
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Target->FirstRelocation = Rels.begin();
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NumRelocations = Rels.size();
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Target->AreRelocsRela = true;
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} else {
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ArrayRef<Elf_Rel> Rels = check(this->getObj().rels(&Sec));
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Target->FirstRelocation = Rels.begin();
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NumRelocations = Rels.size();
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Target->AreRelocsRela = false;
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}
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assert(isUInt<31>(NumRelocations));
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Target->NumRelocations = NumRelocations;
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// Relocation sections processed by the linker are usually removed
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// from the output, so returning `nullptr` for the normal case.
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// However, if -emit-relocs is given, we need to leave them in the output.
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// (Some post link analysis tools need this information.)
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if (Config->EmitRelocs) {
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InputSection *RelocSec = make<InputSection>(this, &Sec, Name);
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// We will not emit relocation section if target was discarded.
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Target->DependentSections.push_back(RelocSec);
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return RelocSec;
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}
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return nullptr;
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}
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}
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// The GNU linker uses .note.GNU-stack section as a marker indicating
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// that the code in the object file does not expect that the stack is
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// executable (in terms of NX bit). If all input files have the marker,
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// the GNU linker adds a PT_GNU_STACK segment to tells the loader to
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// make the stack non-executable. Most object files have this section as
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// of 2017.
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//
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// But making the stack non-executable is a norm today for security
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// reasons. Failure to do so may result in a serious security issue.
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// Therefore, we make LLD always add PT_GNU_STACK unless it is
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// explicitly told to do otherwise (by -z execstack). Because the stack
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// executable-ness is controlled solely by command line options,
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// .note.GNU-stack sections are simply ignored.
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if (Name == ".note.GNU-stack")
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return &InputSection::Discarded;
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// Split stacks is a feature to support a discontiguous stack. At least
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// as of 2017, it seems that the feature is not being used widely.
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// Only GNU gold supports that. We don't. For the details about that,
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// see https://gcc.gnu.org/wiki/SplitStacks
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if (Name == ".note.GNU-split-stack") {
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error(toString(this) +
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": object file compiled with -fsplit-stack is not supported");
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return &InputSection::Discarded;
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}
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if (Config->Strip != StripPolicy::None && Name.startswith(".debug"))
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return &InputSection::Discarded;
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// The linkonce feature is a sort of proto-comdat. Some glibc i386 object
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|
// files contain definitions of symbol "__x86.get_pc_thunk.bx" in linkonce
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// sections. Drop those sections to avoid duplicate symbol errors.
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// FIXME: This is glibc PR20543, we should remove this hack once that has been
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// fixed for a while.
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if (Name.startswith(".gnu.linkonce."))
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return &InputSection::Discarded;
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// The linker merges EH (exception handling) frames and creates a
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// .eh_frame_hdr section for runtime. So we handle them with a special
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// class. For relocatable outputs, they are just passed through.
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if (Name == ".eh_frame" && !Config->Relocatable)
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return make<EhInputSection<ELFT>>(this, &Sec, Name);
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if (shouldMerge(Sec))
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return make<MergeInputSection<ELFT>>(this, &Sec, Name);
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return make<InputSection>(this, &Sec, Name);
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}
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|
|
template <class ELFT> void elf::ObjectFile<ELFT>::initializeSymbols() {
|
|
SymbolBodies.reserve(this->Symbols.size());
|
|
for (const Elf_Sym &Sym : this->Symbols)
|
|
SymbolBodies.push_back(createSymbolBody(&Sym));
|
|
}
|
|
|
|
template <class ELFT>
|
|
InputSectionBase *elf::ObjectFile<ELFT>::getSection(const Elf_Sym &Sym) const {
|
|
uint32_t Index = this->getSectionIndex(Sym);
|
|
if (Index >= Sections.size())
|
|
fatal(toString(this) + ": invalid section index: " + Twine(Index));
|
|
InputSectionBase *S = Sections[Index];
|
|
|
|
// We found that GNU assembler 2.17.50 [FreeBSD] 2007-07-03 could
|
|
// generate broken objects. STT_SECTION/STT_NOTYPE symbols can be
|
|
// associated with SHT_REL[A]/SHT_SYMTAB/SHT_STRTAB sections.
|
|
// In this case it is fine for section to be null here as we do not
|
|
// allocate sections of these types.
|
|
if (!S) {
|
|
if (Index == 0 || Sym.getType() == STT_SECTION ||
|
|
Sym.getType() == STT_NOTYPE)
|
|
return nullptr;
|
|
fatal(toString(this) + ": invalid section index: " + Twine(Index));
|
|
}
|
|
|
|
if (S == &InputSection::Discarded)
|
|
return S;
|
|
return S->Repl;
|
|
}
|
|
|
|
template <class ELFT>
|
|
SymbolBody *elf::ObjectFile<ELFT>::createSymbolBody(const Elf_Sym *Sym) {
|
|
int Binding = Sym->getBinding();
|
|
InputSectionBase *Sec = getSection(*Sym);
|
|
|
|
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));
|
|
|
|
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>(Name, /*IsLocal=*/true, StOther, Type, this);
|
|
|
|
return make<DefinedRegular>(Name, /*IsLocal=*/true, StOther, Type, Value,
|
|
Size, Sec, this);
|
|
}
|
|
|
|
StringRef Name = check(Sym->getName(this->StringTable));
|
|
|
|
switch (Sym->st_shndx) {
|
|
case SHN_UNDEF:
|
|
return elf::Symtab<ELFT>::X
|
|
->addUndefined(Name, /*IsLocal=*/false, Binding, StOther, Type,
|
|
/*CanOmitFromDynSym=*/false, this)
|
|
->body();
|
|
case SHN_COMMON:
|
|
if (Value == 0 || Value >= UINT32_MAX)
|
|
fatal(toString(this) + ": common symbol '" + Name +
|
|
"' has invalid alignment: " + Twine(Value));
|
|
return elf::Symtab<ELFT>::X
|
|
->addCommon(Name, Size, Value, Binding, StOther, Type, this)
|
|
->body();
|
|
}
|
|
|
|
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 elf::Symtab<ELFT>::X
|
|
->addUndefined(Name, /*IsLocal=*/false, Binding, StOther, Type,
|
|
/*CanOmitFromDynSym=*/false, this)
|
|
->body();
|
|
return elf::Symtab<ELFT>::X
|
|
->addRegular(Name, StOther, Type, Value, Size, Binding, Sec, this)
|
|
->body();
|
|
}
|
|
}
|
|
|
|
template <class ELFT> void ArchiveFile::parse() {
|
|
File = check(Archive::create(MB),
|
|
MB.getBufferIdentifier() + ": failed to parse archive");
|
|
|
|
// Read the symbol table to construct Lazy objects.
|
|
for (const Archive::Symbol &Sym : File->symbols())
|
|
Symtab<ELFT>::X->addLazyArchive(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(),
|
|
"could not get the member for symbol " + Sym->getName());
|
|
|
|
if (!Seen.insert(C.getChildOffset()).second)
|
|
return {MemoryBufferRef(), 0};
|
|
|
|
MemoryBufferRef Ret =
|
|
check(C.getMemoryBufferRef(),
|
|
"could not get the buffer for the member defining symbol " +
|
|
Sym->getName());
|
|
|
|
if (C.getParent()->isThin() && Tar)
|
|
Tar->append(relativeToRoot(check(C.getFullName())), Ret.getBuffer());
|
|
if (C.getParent()->isThin())
|
|
return {Ret, 0};
|
|
return {Ret, C.getChildOffset()};
|
|
}
|
|
|
|
template <class ELFT>
|
|
SharedFile<ELFT>::SharedFile(MemoryBufferRef M)
|
|
: ELFFileBase<ELFT>(Base::SharedKind, M), AsNeeded(Config->AsNeeded) {}
|
|
|
|
template <class ELFT>
|
|
const typename ELFT::Shdr *
|
|
SharedFile<ELFT>::getSection(const Elf_Sym &Sym) const {
|
|
return check(
|
|
this->getObj().getSection(&Sym, this->Symbols, this->SymtabSHNDX));
|
|
}
|
|
|
|
// 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());
|
|
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));
|
|
break;
|
|
case SHT_GNU_versym:
|
|
this->VersymSec = &Sec;
|
|
break;
|
|
case SHT_GNU_verdef:
|
|
this->VerdefSec = &Sec;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (this->VersymSec && this->Symbols.empty())
|
|
error("SHT_GNU_versym should be associated with symbol table");
|
|
|
|
// DSOs are identified by soname, and they usually contain
|
|
// DT_SONAME tag in their header. But if they are missing,
|
|
// filenames are used as default sonames.
|
|
SoName = sys::path::filename(this->getName());
|
|
|
|
if (!DynamicSec)
|
|
return;
|
|
|
|
ArrayRef<Elf_Dyn> Arr =
|
|
check(Obj.template getSectionContentsAsArray<Elf_Dyn>(DynamicSec),
|
|
toString(this) + ": getSectionContentsAsArray failed");
|
|
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 = StringRef(this->StringTable.data() + Val);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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. The array
|
|
// always has at least length 1.
|
|
template <class ELFT>
|
|
std::vector<const typename ELFT::Verdef *>
|
|
SharedFile<ELFT>::parseVerdefs(const Elf_Versym *&Versym) {
|
|
std::vector<const Elf_Verdef *> Verdefs(1);
|
|
// We only need to process symbol versions for this DSO if it has both a
|
|
// versym and a verdef section, which indicates that the DSO contains symbol
|
|
// version definitions.
|
|
if (!VersymSec || !VerdefSec)
|
|
return Verdefs;
|
|
|
|
// The location of the first global versym entry.
|
|
const char *Base = this->MB.getBuffer().data();
|
|
Versym = reinterpret_cast<const Elf_Versym *>(Base + VersymSec->sh_offset) +
|
|
this->FirstNonLocal;
|
|
|
|
// 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;
|
|
Verdefs.resize(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 *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;
|
|
}
|
|
|
|
// Fully parse the shared object file. This must be called after parseSoName().
|
|
template <class ELFT> void SharedFile<ELFT>::parseRest() {
|
|
// Create mapping from version identifiers to Elf_Verdef entries.
|
|
const Elf_Versym *Versym = nullptr;
|
|
std::vector<const Elf_Verdef *> Verdefs = parseVerdefs(Versym);
|
|
|
|
Elf_Sym_Range Syms = this->getGlobalSymbols();
|
|
for (const Elf_Sym &Sym : Syms) {
|
|
unsigned VersymIndex = 0;
|
|
if (Versym) {
|
|
VersymIndex = Versym->vs_index;
|
|
++Versym;
|
|
}
|
|
bool Hidden = VersymIndex & VERSYM_HIDDEN;
|
|
VersymIndex = VersymIndex & ~VERSYM_HIDDEN;
|
|
|
|
StringRef Name = check(Sym.getName(this->StringTable));
|
|
if (Sym.isUndefined()) {
|
|
Undefs.push_back(Name);
|
|
continue;
|
|
}
|
|
|
|
// Ignore local symbols.
|
|
if (Versym && VersymIndex == VER_NDX_LOCAL)
|
|
continue;
|
|
|
|
const Elf_Verdef *V =
|
|
VersymIndex == VER_NDX_GLOBAL ? nullptr : Verdefs[VersymIndex];
|
|
|
|
if (!Hidden)
|
|
elf::Symtab<ELFT>::X->addShared(this, Name, Sym, V);
|
|
|
|
// Also add the symbol with the versioned name to handle undefined symbols
|
|
// with explicit versions.
|
|
if (V) {
|
|
StringRef VerName = this->StringTable.data() + V->getAux()->vda_name;
|
|
Name = Saver.save(Twine(Name) + "@" + VerName);
|
|
elf::Symtab<ELFT>::X->addShared(this, Name, Sym, V);
|
|
}
|
|
}
|
|
}
|
|
|
|
static ELFKind getBitcodeELFKind(MemoryBufferRef MB) {
|
|
Triple T(check(getBitcodeTargetTriple(MB)));
|
|
if (T.isLittleEndian())
|
|
return T.isArch64Bit() ? ELF64LEKind : ELF32LEKind;
|
|
return T.isArch64Bit() ? ELF64BEKind : ELF32BEKind;
|
|
}
|
|
|
|
static uint8_t getBitcodeMachineKind(MemoryBufferRef MB) {
|
|
Triple T(check(getBitcodeTargetTriple(MB)));
|
|
switch (T.getArch()) {
|
|
case Triple::aarch64:
|
|
return EM_AARCH64;
|
|
case Triple::arm:
|
|
case Triple::thumb:
|
|
return EM_ARM;
|
|
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(MB.getBufferIdentifier() +
|
|
": could not infer e_machine from bitcode target triple " + T.str());
|
|
}
|
|
}
|
|
|
|
BitcodeFile::BitcodeFile(MemoryBufferRef MB) : InputFile(BitcodeKind, MB) {
|
|
EKind = getBitcodeELFKind(MB);
|
|
EMachine = getBitcodeMachineKind(MB);
|
|
}
|
|
|
|
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 Flags = ObjSym.getFlags();
|
|
uint32_t Binding = (Flags & BasicSymbolRef::SF_Weak) ? 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 = check(ObjSym.getComdatIndex());
|
|
if (C != -1 && !KeptComdats[C])
|
|
return Symtab<ELFT>::X->addUndefined(NameRef, /*IsLocal=*/false, Binding,
|
|
Visibility, Type, CanOmitFromDynSym,
|
|
F);
|
|
|
|
if (Flags & BasicSymbolRef::SF_Undefined)
|
|
return Symtab<ELFT>::X->addUndefined(NameRef, /*IsLocal=*/false, Binding,
|
|
Visibility, Type, CanOmitFromDynSym,
|
|
F);
|
|
|
|
if (Flags & BasicSymbolRef::SF_Common)
|
|
return Symtab<ELFT>::X->addCommon(NameRef, ObjSym.getCommonSize(),
|
|
ObjSym.getCommonAlignment(), Binding,
|
|
Visibility, STT_OBJECT, F);
|
|
|
|
return Symtab<ELFT>::X->addBitcode(NameRef, Binding, Visibility, Type,
|
|
CanOmitFromDynSym, F);
|
|
}
|
|
|
|
template <class ELFT>
|
|
void BitcodeFile::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
|
|
|
|
// 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).
|
|
Obj = check(lto::InputFile::create(MemoryBufferRef(
|
|
MB.getBuffer(), Saver.save(ArchiveName + MB.getBufferIdentifier() +
|
|
utostr(OffsetInArchive)))));
|
|
|
|
std::vector<bool> KeptComdats;
|
|
for (StringRef S : Obj->getComdatTable()) {
|
|
StringRef N = Saver.save(S);
|
|
KeptComdats.push_back(ComdatGroups.insert(CachedHashStringRef(N)).second);
|
|
}
|
|
|
|
for (const lto::InputFile::Symbol &ObjSym : Obj->symbols())
|
|
Symbols.push_back(createBitcodeSymbol<ELFT>(KeptComdats, ObjSym, this));
|
|
}
|
|
|
|
template <template <class> class T>
|
|
static InputFile *createELFFile(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");
|
|
|
|
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");
|
|
|
|
InputFile *Obj;
|
|
if (Size == ELFCLASS32 && Endian == ELFDATA2LSB)
|
|
Obj = make<T<ELF32LE>>(MB);
|
|
else if (Size == ELFCLASS32 && Endian == ELFDATA2MSB)
|
|
Obj = make<T<ELF32BE>>(MB);
|
|
else if (Size == ELFCLASS64 && Endian == ELFDATA2LSB)
|
|
Obj = make<T<ELF64LE>>(MB);
|
|
else if (Size == ELFCLASS64 && Endian == ELFDATA2MSB)
|
|
Obj = make<T<ELF64BE>>(MB);
|
|
else
|
|
fatal(MB.getBufferIdentifier() + ": invalid file class");
|
|
|
|
if (!Config->FirstElf)
|
|
Config->FirstElf = Obj;
|
|
return Obj;
|
|
}
|
|
|
|
template <class ELFT> void BinaryFile::parse() {
|
|
StringRef Buf = MB.getBuffer();
|
|
ArrayRef<uint8_t> Data =
|
|
makeArrayRef<uint8_t>((const uint8_t *)Buf.data(), Buf.size());
|
|
|
|
std::string Filename = MB.getBufferIdentifier();
|
|
std::transform(Filename.begin(), Filename.end(), Filename.begin(),
|
|
[](char C) { return isalnum(C) ? C : '_'; });
|
|
Filename = "_binary_" + Filename;
|
|
StringRef StartName = Saver.save(Twine(Filename) + "_start");
|
|
StringRef EndName = Saver.save(Twine(Filename) + "_end");
|
|
StringRef SizeName = Saver.save(Twine(Filename) + "_size");
|
|
|
|
auto *Section =
|
|
make<InputSection>(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS, 8, Data, ".data");
|
|
Sections.push_back(Section);
|
|
|
|
elf::Symtab<ELFT>::X->addRegular(StartName, STV_DEFAULT, STT_OBJECT, 0, 0,
|
|
STB_GLOBAL, Section, nullptr);
|
|
elf::Symtab<ELFT>::X->addRegular(EndName, STV_DEFAULT, STT_OBJECT,
|
|
Data.size(), 0, STB_GLOBAL, Section,
|
|
nullptr);
|
|
elf::Symtab<ELFT>::X->addRegular(SizeName, 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) {
|
|
InputFile *F =
|
|
isBitcode(MB) ? make<BitcodeFile>(MB) : createELFFile<ObjectFile>(MB);
|
|
F->ArchiveName = ArchiveName;
|
|
F->OffsetInArchive = OffsetInArchive;
|
|
return F;
|
|
}
|
|
|
|
InputFile *elf::createSharedFile(MemoryBufferRef MB) {
|
|
return createELFFile<SharedFile>(MB);
|
|
}
|
|
|
|
MemoryBufferRef LazyObjectFile::getBuffer() {
|
|
if (Seen)
|
|
return MemoryBufferRef();
|
|
Seen = true;
|
|
return MB;
|
|
}
|
|
|
|
template <class ELFT> void LazyObjectFile::parse() {
|
|
for (StringRef Sym : getSymbols())
|
|
Symtab<ELFT>::X->addLazyObject(Sym, *this);
|
|
}
|
|
|
|
template <class ELFT> std::vector<StringRef> LazyObjectFile::getElfSymbols() {
|
|
typedef typename ELFT::Shdr Elf_Shdr;
|
|
typedef typename ELFT::Sym Elf_Sym;
|
|
typedef typename ELFT::SymRange Elf_Sym_Range;
|
|
|
|
const ELFFile<ELFT> Obj(this->MB.getBuffer());
|
|
ArrayRef<Elf_Shdr> Sections = check(Obj.sections());
|
|
for (const Elf_Shdr &Sec : Sections) {
|
|
if (Sec.sh_type != SHT_SYMTAB)
|
|
continue;
|
|
Elf_Sym_Range Syms = check(Obj.symbols(&Sec));
|
|
uint32_t FirstNonLocal = Sec.sh_info;
|
|
StringRef StringTable = check(Obj.getStringTableForSymtab(Sec, Sections));
|
|
std::vector<StringRef> V;
|
|
for (const Elf_Sym &Sym : Syms.slice(FirstNonLocal))
|
|
if (Sym.st_shndx != SHN_UNDEF)
|
|
V.push_back(check(Sym.getName(StringTable)));
|
|
return V;
|
|
}
|
|
return {};
|
|
}
|
|
|
|
std::vector<StringRef> LazyObjectFile::getBitcodeSymbols() {
|
|
std::unique_ptr<lto::InputFile> Obj = check(lto::InputFile::create(this->MB));
|
|
std::vector<StringRef> V;
|
|
for (const lto::InputFile::Symbol &Sym : Obj->symbols())
|
|
if (!(Sym.getFlags() & BasicSymbolRef::SF_Undefined))
|
|
V.push_back(Saver.save(Sym.getName()));
|
|
return V;
|
|
}
|
|
|
|
// Returns a vector of globally-visible defined symbol names.
|
|
std::vector<StringRef> LazyObjectFile::getSymbols() {
|
|
if (isBitcode(this->MB))
|
|
return getBitcodeSymbols();
|
|
|
|
unsigned char Size;
|
|
unsigned char Endian;
|
|
std::tie(Size, Endian) = getElfArchType(this->MB.getBuffer());
|
|
if (Size == ELFCLASS32) {
|
|
if (Endian == ELFDATA2LSB)
|
|
return getElfSymbols<ELF32LE>();
|
|
return getElfSymbols<ELF32BE>();
|
|
}
|
|
if (Endian == ELFDATA2LSB)
|
|
return getElfSymbols<ELF64LE>();
|
|
return getElfSymbols<ELF64BE>();
|
|
}
|
|
|
|
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 LazyObjectFile::parse<ELF32LE>();
|
|
template void LazyObjectFile::parse<ELF32BE>();
|
|
template void LazyObjectFile::parse<ELF64LE>();
|
|
template void LazyObjectFile::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::ObjectFile<ELF32LE>;
|
|
template class elf::ObjectFile<ELF32BE>;
|
|
template class elf::ObjectFile<ELF64LE>;
|
|
template class elf::ObjectFile<ELF64BE>;
|
|
|
|
template class elf::SharedFile<ELF32LE>;
|
|
template class elf::SharedFile<ELF32BE>;
|
|
template class elf::SharedFile<ELF64LE>;
|
|
template class elf::SharedFile<ELF64BE>;
|
|
|
|
template void BinaryFile::parse<ELF32LE>();
|
|
template void BinaryFile::parse<ELF32BE>();
|
|
template void BinaryFile::parse<ELF64LE>();
|
|
template void BinaryFile::parse<ELF64BE>();
|