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-rw-r--r--contrib/llvm/lib/MC/ELFObjectWriter.cpp1838
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diff --git a/contrib/llvm/lib/MC/ELFObjectWriter.cpp b/contrib/llvm/lib/MC/ELFObjectWriter.cpp
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+++ b/contrib/llvm/lib/MC/ELFObjectWriter.cpp
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+//===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -----------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements ELF object file writer information.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCELFObjectWriter.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/MC/MCAsmBackend.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCAsmLayout.h"
+#include "llvm/MC/MCAssembler.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCELF.h"
+#include "llvm/MC/MCELFSymbolFlags.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCFixupKindInfo.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCValue.h"
+#include "llvm/MC/StringTableBuilder.h"
+#include "llvm/Support/Compression.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/ELF.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <vector>
+using namespace llvm;
+
+#undef DEBUG_TYPE
+#define DEBUG_TYPE "reloc-info"
+
+namespace {
+class FragmentWriter {
+ bool IsLittleEndian;
+
+public:
+ FragmentWriter(bool IsLittleEndian);
+ template <typename T> void write(MCDataFragment &F, T Val);
+};
+
+typedef DenseMap<const MCSectionELF *, uint32_t> SectionIndexMapTy;
+
+class SymbolTableWriter {
+ MCAssembler &Asm;
+ FragmentWriter &FWriter;
+ bool Is64Bit;
+ SectionIndexMapTy &SectionIndexMap;
+
+ // The symbol .symtab fragment we are writting to.
+ MCDataFragment *SymtabF;
+
+ // .symtab_shndx fragment we are writting to.
+ MCDataFragment *ShndxF;
+
+ // The numbel of symbols written so far.
+ unsigned NumWritten;
+
+ void createSymtabShndx();
+
+ template <typename T> void write(MCDataFragment &F, T Value);
+
+public:
+ SymbolTableWriter(MCAssembler &Asm, FragmentWriter &FWriter, bool Is64Bit,
+ SectionIndexMapTy &SectionIndexMap,
+ MCDataFragment *SymtabF);
+
+ void writeSymbol(uint32_t name, uint8_t info, uint64_t value, uint64_t size,
+ uint8_t other, uint32_t shndx, bool Reserved);
+};
+
+struct ELFRelocationEntry {
+ uint64_t Offset; // Where is the relocation.
+ bool UseSymbol; // Relocate with a symbol, not the section.
+ union {
+ const MCSymbol *Symbol; // The symbol to relocate with.
+ const MCSectionData *Section; // The section to relocate with.
+ };
+ unsigned Type; // The type of the relocation.
+ uint64_t Addend; // The addend to use.
+
+ ELFRelocationEntry(uint64_t Offset, const MCSymbol *Symbol, unsigned Type,
+ uint64_t Addend)
+ : Offset(Offset), UseSymbol(true), Symbol(Symbol), Type(Type),
+ Addend(Addend) {}
+
+ ELFRelocationEntry(uint64_t Offset, const MCSectionData *Section,
+ unsigned Type, uint64_t Addend)
+ : Offset(Offset), UseSymbol(false), Section(Section), Type(Type),
+ Addend(Addend) {}
+};
+
+class ELFObjectWriter : public MCObjectWriter {
+ FragmentWriter FWriter;
+
+ protected:
+
+ static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
+ static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant);
+ static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout);
+ static bool isInSymtab(const MCAsmLayout &Layout, const MCSymbolData &Data,
+ bool Used, bool Renamed);
+ static bool isLocal(const MCSymbolData &Data, bool isUsedInReloc);
+ static bool IsELFMetaDataSection(const MCSectionData &SD);
+ static uint64_t DataSectionSize(const MCSectionData &SD);
+ static uint64_t GetSectionFileSize(const MCAsmLayout &Layout,
+ const MCSectionData &SD);
+ static uint64_t GetSectionAddressSize(const MCAsmLayout &Layout,
+ const MCSectionData &SD);
+
+ void WriteDataSectionData(MCAssembler &Asm,
+ const MCAsmLayout &Layout,
+ const MCSectionELF &Section);
+
+ /*static bool isFixupKindX86RIPRel(unsigned Kind) {
+ return Kind == X86::reloc_riprel_4byte ||
+ Kind == X86::reloc_riprel_4byte_movq_load;
+ }*/
+
+ /// ELFSymbolData - Helper struct for containing some precomputed
+ /// information on symbols.
+ struct ELFSymbolData {
+ MCSymbolData *SymbolData;
+ uint64_t StringIndex;
+ uint32_t SectionIndex;
+ StringRef Name;
+
+ // Support lexicographic sorting.
+ bool operator<(const ELFSymbolData &RHS) const {
+ return Name < RHS.Name;
+ }
+ };
+
+ /// The target specific ELF writer instance.
+ std::unique_ptr<MCELFObjectTargetWriter> TargetObjectWriter;
+
+ SmallPtrSet<const MCSymbol *, 16> UsedInReloc;
+ SmallPtrSet<const MCSymbol *, 16> WeakrefUsedInReloc;
+ DenseMap<const MCSymbol *, const MCSymbol *> Renames;
+
+ llvm::DenseMap<const MCSectionData *, std::vector<ELFRelocationEntry>>
+ Relocations;
+ StringTableBuilder ShStrTabBuilder;
+
+ /// @}
+ /// @name Symbol Table Data
+ /// @{
+
+ StringTableBuilder StrTabBuilder;
+ std::vector<uint64_t> FileSymbolData;
+ std::vector<ELFSymbolData> LocalSymbolData;
+ std::vector<ELFSymbolData> ExternalSymbolData;
+ std::vector<ELFSymbolData> UndefinedSymbolData;
+
+ /// @}
+
+ bool NeedsGOT;
+
+ // This holds the symbol table index of the last local symbol.
+ unsigned LastLocalSymbolIndex;
+ // This holds the .strtab section index.
+ unsigned StringTableIndex;
+ // This holds the .symtab section index.
+ unsigned SymbolTableIndex;
+
+ unsigned ShstrtabIndex;
+
+
+ // TargetObjectWriter wrappers.
+ bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
+ bool hasRelocationAddend() const {
+ return TargetObjectWriter->hasRelocationAddend();
+ }
+ unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
+ bool IsPCRel) const {
+ return TargetObjectWriter->GetRelocType(Target, Fixup, IsPCRel);
+ }
+
+ public:
+ ELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &_OS,
+ bool IsLittleEndian)
+ : MCObjectWriter(_OS, IsLittleEndian), FWriter(IsLittleEndian),
+ TargetObjectWriter(MOTW), NeedsGOT(false) {}
+
+ virtual ~ELFObjectWriter();
+
+ void WriteWord(uint64_t W) {
+ if (is64Bit())
+ Write64(W);
+ else
+ Write32(W);
+ }
+
+ template <typename T> void write(MCDataFragment &F, T Value) {
+ FWriter.write(F, Value);
+ }
+
+ void WriteHeader(const MCAssembler &Asm,
+ uint64_t SectionDataSize,
+ unsigned NumberOfSections);
+
+ void WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD,
+ const MCAsmLayout &Layout);
+
+ void WriteSymbolTable(MCDataFragment *SymtabF, MCAssembler &Asm,
+ const MCAsmLayout &Layout,
+ SectionIndexMapTy &SectionIndexMap);
+
+ bool shouldRelocateWithSymbol(const MCAssembler &Asm,
+ const MCSymbolRefExpr *RefA,
+ const MCSymbolData *SD, uint64_t C,
+ unsigned Type) const;
+
+ void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
+ const MCFragment *Fragment, const MCFixup &Fixup,
+ MCValue Target, bool &IsPCRel,
+ uint64_t &FixedValue) override;
+
+ uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
+ const MCSymbol *S);
+
+ // Map from a group section to the signature symbol
+ typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
+ // Map from a signature symbol to the group section
+ typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
+ // Map from a section to the section with the relocations
+ typedef DenseMap<const MCSectionELF*, const MCSectionELF*> RelMapTy;
+ // Map from a section to its offset
+ typedef DenseMap<const MCSectionELF*, uint64_t> SectionOffsetMapTy;
+
+ /// Compute the symbol table data
+ ///
+ /// \param Asm - The assembler.
+ /// \param SectionIndexMap - Maps a section to its index.
+ /// \param RevGroupMap - Maps a signature symbol to the group section.
+ /// \param NumRegularSections - Number of non-relocation sections.
+ void computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
+ const SectionIndexMapTy &SectionIndexMap,
+ RevGroupMapTy RevGroupMap,
+ unsigned NumRegularSections);
+
+ void ComputeIndexMap(MCAssembler &Asm,
+ SectionIndexMapTy &SectionIndexMap,
+ const RelMapTy &RelMap);
+
+ void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout,
+ RelMapTy &RelMap);
+
+ void CompressDebugSections(MCAssembler &Asm, MCAsmLayout &Layout);
+
+ void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
+ const RelMapTy &RelMap);
+
+ void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
+ SectionIndexMapTy &SectionIndexMap,
+ const RelMapTy &RelMap);
+
+ // Create the sections that show up in the symbol table. Currently
+ // those are the .note.GNU-stack section and the group sections.
+ void CreateIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout,
+ GroupMapTy &GroupMap,
+ RevGroupMapTy &RevGroupMap,
+ SectionIndexMapTy &SectionIndexMap,
+ const RelMapTy &RelMap);
+
+ void ExecutePostLayoutBinding(MCAssembler &Asm,
+ const MCAsmLayout &Layout) override;
+
+ void WriteSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap,
+ const MCAsmLayout &Layout,
+ const SectionIndexMapTy &SectionIndexMap,
+ const SectionOffsetMapTy &SectionOffsetMap);
+
+ void ComputeSectionOrder(MCAssembler &Asm,
+ std::vector<const MCSectionELF*> &Sections);
+
+ void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
+ uint64_t Address, uint64_t Offset,
+ uint64_t Size, uint32_t Link, uint32_t Info,
+ uint64_t Alignment, uint64_t EntrySize);
+
+ void WriteRelocationsFragment(const MCAssembler &Asm,
+ MCDataFragment *F,
+ const MCSectionData *SD);
+
+ bool
+ IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
+ const MCSymbolData &DataA,
+ const MCFragment &FB,
+ bool InSet,
+ bool IsPCRel) const override;
+
+ void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
+ void WriteSection(MCAssembler &Asm,
+ const SectionIndexMapTy &SectionIndexMap,
+ uint32_t GroupSymbolIndex,
+ uint64_t Offset, uint64_t Size, uint64_t Alignment,
+ const MCSectionELF &Section);
+ };
+}
+
+FragmentWriter::FragmentWriter(bool IsLittleEndian)
+ : IsLittleEndian(IsLittleEndian) {}
+
+template <typename T> void FragmentWriter::write(MCDataFragment &F, T Val) {
+ if (IsLittleEndian)
+ Val = support::endian::byte_swap<T, support::little>(Val);
+ else
+ Val = support::endian::byte_swap<T, support::big>(Val);
+ const char *Start = (const char *)&Val;
+ F.getContents().append(Start, Start + sizeof(T));
+}
+
+void SymbolTableWriter::createSymtabShndx() {
+ if (ShndxF)
+ return;
+
+ MCContext &Ctx = Asm.getContext();
+ const MCSectionELF *SymtabShndxSection =
+ Ctx.getELFSection(".symtab_shndxr", ELF::SHT_SYMTAB_SHNDX, 0,
+ SectionKind::getReadOnly(), 4, "");
+ MCSectionData *SymtabShndxSD =
+ &Asm.getOrCreateSectionData(*SymtabShndxSection);
+ SymtabShndxSD->setAlignment(4);
+ ShndxF = new MCDataFragment(SymtabShndxSD);
+ unsigned Index = SectionIndexMap.size() + 1;
+ SectionIndexMap[SymtabShndxSection] = Index;
+
+ for (unsigned I = 0; I < NumWritten; ++I)
+ write(*ShndxF, uint32_t(0));
+}
+
+template <typename T>
+void SymbolTableWriter::write(MCDataFragment &F, T Value) {
+ FWriter.write(F, Value);
+}
+
+SymbolTableWriter::SymbolTableWriter(MCAssembler &Asm, FragmentWriter &FWriter,
+ bool Is64Bit,
+ SectionIndexMapTy &SectionIndexMap,
+ MCDataFragment *SymtabF)
+ : Asm(Asm), FWriter(FWriter), Is64Bit(Is64Bit),
+ SectionIndexMap(SectionIndexMap), SymtabF(SymtabF), ShndxF(nullptr),
+ NumWritten(0) {}
+
+void SymbolTableWriter::writeSymbol(uint32_t name, uint8_t info, uint64_t value,
+ uint64_t size, uint8_t other,
+ uint32_t shndx, bool Reserved) {
+ bool LargeIndex = shndx >= ELF::SHN_LORESERVE && !Reserved;
+
+ if (LargeIndex)
+ createSymtabShndx();
+
+ if (ShndxF) {
+ if (LargeIndex)
+ write(*ShndxF, shndx);
+ else
+ write(*ShndxF, uint32_t(0));
+ }
+
+ uint16_t Index = LargeIndex ? uint16_t(ELF::SHN_XINDEX) : shndx;
+
+ raw_svector_ostream OS(SymtabF->getContents());
+
+ if (Is64Bit) {
+ write(*SymtabF, name); // st_name
+ write(*SymtabF, info); // st_info
+ write(*SymtabF, other); // st_other
+ write(*SymtabF, Index); // st_shndx
+ write(*SymtabF, value); // st_value
+ write(*SymtabF, size); // st_size
+ } else {
+ write(*SymtabF, name); // st_name
+ write(*SymtabF, uint32_t(value)); // st_value
+ write(*SymtabF, uint32_t(size)); // st_size
+ write(*SymtabF, info); // st_info
+ write(*SymtabF, other); // st_other
+ write(*SymtabF, Index); // st_shndx
+ }
+
+ ++NumWritten;
+}
+
+bool ELFObjectWriter::isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) {
+ const MCFixupKindInfo &FKI =
+ Asm.getBackend().getFixupKindInfo((MCFixupKind) Kind);
+
+ return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel;
+}
+
+bool ELFObjectWriter::RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) {
+ switch (Variant) {
+ default:
+ return false;
+ case MCSymbolRefExpr::VK_GOT:
+ case MCSymbolRefExpr::VK_PLT:
+ case MCSymbolRefExpr::VK_GOTPCREL:
+ case MCSymbolRefExpr::VK_GOTOFF:
+ case MCSymbolRefExpr::VK_TPOFF:
+ case MCSymbolRefExpr::VK_TLSGD:
+ case MCSymbolRefExpr::VK_GOTTPOFF:
+ case MCSymbolRefExpr::VK_INDNTPOFF:
+ case MCSymbolRefExpr::VK_NTPOFF:
+ case MCSymbolRefExpr::VK_GOTNTPOFF:
+ case MCSymbolRefExpr::VK_TLSLDM:
+ case MCSymbolRefExpr::VK_DTPOFF:
+ case MCSymbolRefExpr::VK_TLSLD:
+ return true;
+ }
+}
+
+ELFObjectWriter::~ELFObjectWriter()
+{}
+
+// Emit the ELF header.
+void ELFObjectWriter::WriteHeader(const MCAssembler &Asm,
+ uint64_t SectionDataSize,
+ unsigned NumberOfSections) {
+ // ELF Header
+ // ----------
+ //
+ // Note
+ // ----
+ // emitWord method behaves differently for ELF32 and ELF64, writing
+ // 4 bytes in the former and 8 in the latter.
+
+ Write8(0x7f); // e_ident[EI_MAG0]
+ Write8('E'); // e_ident[EI_MAG1]
+ Write8('L'); // e_ident[EI_MAG2]
+ Write8('F'); // e_ident[EI_MAG3]
+
+ Write8(is64Bit() ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
+
+ // e_ident[EI_DATA]
+ Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
+
+ Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION]
+ // e_ident[EI_OSABI]
+ Write8(TargetObjectWriter->getOSABI());
+ Write8(0); // e_ident[EI_ABIVERSION]
+
+ WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
+
+ Write16(ELF::ET_REL); // e_type
+
+ Write16(TargetObjectWriter->getEMachine()); // e_machine = target
+
+ Write32(ELF::EV_CURRENT); // e_version
+ WriteWord(0); // e_entry, no entry point in .o file
+ WriteWord(0); // e_phoff, no program header for .o
+ WriteWord(SectionDataSize + (is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
+ sizeof(ELF::Elf32_Ehdr))); // e_shoff = sec hdr table off in bytes
+
+ // e_flags = whatever the target wants
+ Write32(Asm.getELFHeaderEFlags());
+
+ // e_ehsize = ELF header size
+ Write16(is64Bit() ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr));
+
+ Write16(0); // e_phentsize = prog header entry size
+ Write16(0); // e_phnum = # prog header entries = 0
+
+ // e_shentsize = Section header entry size
+ Write16(is64Bit() ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr));
+
+ // e_shnum = # of section header ents
+ if (NumberOfSections >= ELF::SHN_LORESERVE)
+ Write16(ELF::SHN_UNDEF);
+ else
+ Write16(NumberOfSections);
+
+ // e_shstrndx = Section # of '.shstrtab'
+ if (ShstrtabIndex >= ELF::SHN_LORESERVE)
+ Write16(ELF::SHN_XINDEX);
+ else
+ Write16(ShstrtabIndex);
+}
+
+uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data,
+ const MCAsmLayout &Layout) {
+ if (Data.isCommon() && Data.isExternal())
+ return Data.getCommonAlignment();
+
+ uint64_t Res;
+ if (!Layout.getSymbolOffset(&Data, Res))
+ return 0;
+
+ if (Layout.getAssembler().isThumbFunc(&Data.getSymbol()))
+ Res |= 1;
+
+ return Res;
+}
+
+void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
+ const MCAsmLayout &Layout) {
+ // The presence of symbol versions causes undefined symbols and
+ // versions declared with @@@ to be renamed.
+
+ for (MCSymbolData &OriginalData : Asm.symbols()) {
+ const MCSymbol &Alias = OriginalData.getSymbol();
+
+ // Not an alias.
+ if (!Alias.isVariable())
+ continue;
+ auto *Ref = dyn_cast<MCSymbolRefExpr>(Alias.getVariableValue());
+ if (!Ref)
+ continue;
+ const MCSymbol &Symbol = Ref->getSymbol();
+ MCSymbolData &SD = Asm.getSymbolData(Symbol);
+
+ StringRef AliasName = Alias.getName();
+ size_t Pos = AliasName.find('@');
+ if (Pos == StringRef::npos)
+ continue;
+
+ // Aliases defined with .symvar copy the binding from the symbol they alias.
+ // This is the first place we are able to copy this information.
+ OriginalData.setExternal(SD.isExternal());
+ MCELF::SetBinding(OriginalData, MCELF::GetBinding(SD));
+
+ StringRef Rest = AliasName.substr(Pos);
+ if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
+ continue;
+
+ // FIXME: produce a better error message.
+ if (Symbol.isUndefined() && Rest.startswith("@@") &&
+ !Rest.startswith("@@@"))
+ report_fatal_error("A @@ version cannot be undefined");
+
+ Renames.insert(std::make_pair(&Symbol, &Alias));
+ }
+}
+
+static uint8_t mergeTypeForSet(uint8_t origType, uint8_t newType) {
+ uint8_t Type = newType;
+
+ // Propagation rules:
+ // IFUNC > FUNC > OBJECT > NOTYPE
+ // TLS_OBJECT > OBJECT > NOTYPE
+ //
+ // dont let the new type degrade the old type
+ switch (origType) {
+ default:
+ break;
+ case ELF::STT_GNU_IFUNC:
+ if (Type == ELF::STT_FUNC || Type == ELF::STT_OBJECT ||
+ Type == ELF::STT_NOTYPE || Type == ELF::STT_TLS)
+ Type = ELF::STT_GNU_IFUNC;
+ break;
+ case ELF::STT_FUNC:
+ if (Type == ELF::STT_OBJECT || Type == ELF::STT_NOTYPE ||
+ Type == ELF::STT_TLS)
+ Type = ELF::STT_FUNC;
+ break;
+ case ELF::STT_OBJECT:
+ if (Type == ELF::STT_NOTYPE)
+ Type = ELF::STT_OBJECT;
+ break;
+ case ELF::STT_TLS:
+ if (Type == ELF::STT_OBJECT || Type == ELF::STT_NOTYPE ||
+ Type == ELF::STT_GNU_IFUNC || Type == ELF::STT_FUNC)
+ Type = ELF::STT_TLS;
+ break;
+ }
+
+ return Type;
+}
+
+void ELFObjectWriter::WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD,
+ const MCAsmLayout &Layout) {
+ MCSymbolData &OrigData = *MSD.SymbolData;
+ assert((!OrigData.getFragment() ||
+ (&OrigData.getFragment()->getParent()->getSection() ==
+ &OrigData.getSymbol().getSection())) &&
+ "The symbol's section doesn't match the fragment's symbol");
+ const MCSymbol *Base = Layout.getBaseSymbol(OrigData.getSymbol());
+
+ // This has to be in sync with when computeSymbolTable uses SHN_ABS or
+ // SHN_COMMON.
+ bool IsReserved = !Base || OrigData.isCommon();
+
+ // Binding and Type share the same byte as upper and lower nibbles
+ uint8_t Binding = MCELF::GetBinding(OrigData);
+ uint8_t Type = MCELF::GetType(OrigData);
+ MCSymbolData *BaseSD = nullptr;
+ if (Base) {
+ BaseSD = &Layout.getAssembler().getSymbolData(*Base);
+ Type = mergeTypeForSet(Type, MCELF::GetType(*BaseSD));
+ }
+ uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
+
+ // Other and Visibility share the same byte with Visibility using the lower
+ // 2 bits
+ uint8_t Visibility = MCELF::GetVisibility(OrigData);
+ uint8_t Other = MCELF::getOther(OrigData) << (ELF_STO_Shift - ELF_STV_Shift);
+ Other |= Visibility;
+
+ uint64_t Value = SymbolValue(OrigData, Layout);
+ uint64_t Size = 0;
+
+ const MCExpr *ESize = OrigData.getSize();
+ if (!ESize && Base)
+ ESize = BaseSD->getSize();
+
+ if (ESize) {
+ int64_t Res;
+ if (!ESize->EvaluateAsAbsolute(Res, Layout))
+ report_fatal_error("Size expression must be absolute.");
+ Size = Res;
+ }
+
+ // Write out the symbol table entry
+ Writer.writeSymbol(MSD.StringIndex, Info, Value, Size, Other,
+ MSD.SectionIndex, IsReserved);
+}
+
+void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
+ MCAssembler &Asm,
+ const MCAsmLayout &Layout,
+ SectionIndexMapTy &SectionIndexMap) {
+ // The string table must be emitted first because we need the index
+ // into the string table for all the symbol names.
+
+ // FIXME: Make sure the start of the symbol table is aligned.
+
+ SymbolTableWriter Writer(Asm, FWriter, is64Bit(), SectionIndexMap, SymtabF);
+
+ // The first entry is the undefined symbol entry.
+ Writer.writeSymbol(0, 0, 0, 0, 0, 0, false);
+
+ for (unsigned i = 0, e = FileSymbolData.size(); i != e; ++i) {
+ Writer.writeSymbol(FileSymbolData[i], ELF::STT_FILE | ELF::STB_LOCAL, 0, 0,
+ ELF::STV_DEFAULT, ELF::SHN_ABS, true);
+ }
+
+ // Write the symbol table entries.
+ LastLocalSymbolIndex = FileSymbolData.size() + LocalSymbolData.size() + 1;
+
+ for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) {
+ ELFSymbolData &MSD = LocalSymbolData[i];
+ WriteSymbol(Writer, MSD, Layout);
+ }
+
+ // Write out a symbol table entry for each regular section.
+ for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e;
+ ++i) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(i->getSection());
+ if (Section.getType() == ELF::SHT_RELA ||
+ Section.getType() == ELF::SHT_REL ||
+ Section.getType() == ELF::SHT_STRTAB ||
+ Section.getType() == ELF::SHT_SYMTAB ||
+ Section.getType() == ELF::SHT_SYMTAB_SHNDX)
+ continue;
+ Writer.writeSymbol(0, ELF::STT_SECTION, 0, 0, ELF::STV_DEFAULT,
+ SectionIndexMap.lookup(&Section), false);
+ LastLocalSymbolIndex++;
+ }
+
+ for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) {
+ ELFSymbolData &MSD = ExternalSymbolData[i];
+ MCSymbolData &Data = *MSD.SymbolData;
+ assert(((Data.getFlags() & ELF_STB_Global) ||
+ (Data.getFlags() & ELF_STB_Weak)) &&
+ "External symbol requires STB_GLOBAL or STB_WEAK flag");
+ WriteSymbol(Writer, MSD, Layout);
+ if (MCELF::GetBinding(Data) == ELF::STB_LOCAL)
+ LastLocalSymbolIndex++;
+ }
+
+ for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) {
+ ELFSymbolData &MSD = UndefinedSymbolData[i];
+ MCSymbolData &Data = *MSD.SymbolData;
+ WriteSymbol(Writer, MSD, Layout);
+ if (MCELF::GetBinding(Data) == ELF::STB_LOCAL)
+ LastLocalSymbolIndex++;
+ }
+}
+
+// It is always valid to create a relocation with a symbol. It is preferable
+// to use a relocation with a section if that is possible. Using the section
+// allows us to omit some local symbols from the symbol table.
+bool ELFObjectWriter::shouldRelocateWithSymbol(const MCAssembler &Asm,
+ const MCSymbolRefExpr *RefA,
+ const MCSymbolData *SD,
+ uint64_t C,
+ unsigned Type) const {
+ // A PCRel relocation to an absolute value has no symbol (or section). We
+ // represent that with a relocation to a null section.
+ if (!RefA)
+ return false;
+
+ MCSymbolRefExpr::VariantKind Kind = RefA->getKind();
+ switch (Kind) {
+ default:
+ break;
+ // The .odp creation emits a relocation against the symbol ".TOC." which
+ // create a R_PPC64_TOC relocation. However the relocation symbol name
+ // in final object creation should be NULL, since the symbol does not
+ // really exist, it is just the reference to TOC base for the current
+ // object file. Since the symbol is undefined, returning false results
+ // in a relocation with a null section which is the desired result.
+ case MCSymbolRefExpr::VK_PPC_TOCBASE:
+ return false;
+
+ // These VariantKind cause the relocation to refer to something other than
+ // the symbol itself, like a linker generated table. Since the address of
+ // symbol is not relevant, we cannot replace the symbol with the
+ // section and patch the difference in the addend.
+ case MCSymbolRefExpr::VK_GOT:
+ case MCSymbolRefExpr::VK_PLT:
+ case MCSymbolRefExpr::VK_GOTPCREL:
+ case MCSymbolRefExpr::VK_Mips_GOT:
+ case MCSymbolRefExpr::VK_PPC_GOT_LO:
+ case MCSymbolRefExpr::VK_PPC_GOT_HI:
+ case MCSymbolRefExpr::VK_PPC_GOT_HA:
+ return true;
+ }
+
+ // An undefined symbol is not in any section, so the relocation has to point
+ // to the symbol itself.
+ const MCSymbol &Sym = SD->getSymbol();
+ if (Sym.isUndefined())
+ return true;
+
+ unsigned Binding = MCELF::GetBinding(*SD);
+ switch(Binding) {
+ default:
+ llvm_unreachable("Invalid Binding");
+ case ELF::STB_LOCAL:
+ break;
+ case ELF::STB_WEAK:
+ // If the symbol is weak, it might be overridden by a symbol in another
+ // file. The relocation has to point to the symbol so that the linker
+ // can update it.
+ return true;
+ case ELF::STB_GLOBAL:
+ // Global ELF symbols can be preempted by the dynamic linker. The relocation
+ // has to point to the symbol for a reason analogous to the STB_WEAK case.
+ return true;
+ }
+
+ // If a relocation points to a mergeable section, we have to be careful.
+ // If the offset is zero, a relocation with the section will encode the
+ // same information. With a non-zero offset, the situation is different.
+ // For example, a relocation can point 42 bytes past the end of a string.
+ // If we change such a relocation to use the section, the linker would think
+ // that it pointed to another string and subtracting 42 at runtime will
+ // produce the wrong value.
+ auto &Sec = cast<MCSectionELF>(Sym.getSection());
+ unsigned Flags = Sec.getFlags();
+ if (Flags & ELF::SHF_MERGE) {
+ if (C != 0)
+ return true;
+
+ // It looks like gold has a bug (http://sourceware.org/PR16794) and can
+ // only handle section relocations to mergeable sections if using RELA.
+ if (!hasRelocationAddend())
+ return true;
+ }
+
+ // Most TLS relocations use a got, so they need the symbol. Even those that
+ // are just an offset (@tpoff), require a symbol in some linkers (gold,
+ // but not bfd ld).
+ if (Flags & ELF::SHF_TLS)
+ return true;
+
+ // If the symbol is a thumb function the final relocation must set the lowest
+ // bit. With a symbol that is done by just having the symbol have that bit
+ // set, so we would lose the bit if we relocated with the section.
+ // FIXME: We could use the section but add the bit to the relocation value.
+ if (Asm.isThumbFunc(&Sym))
+ return true;
+
+ if (TargetObjectWriter->needsRelocateWithSymbol(*SD, Type))
+ return true;
+ return false;
+}
+
+static const MCSymbol *getWeakRef(const MCSymbolRefExpr &Ref) {
+ const MCSymbol &Sym = Ref.getSymbol();
+
+ if (Ref.getKind() == MCSymbolRefExpr::VK_WEAKREF)
+ return &Sym;
+
+ if (!Sym.isVariable())
+ return nullptr;
+
+ const MCExpr *Expr = Sym.getVariableValue();
+ const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
+ if (!Inner)
+ return nullptr;
+
+ if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
+ return &Inner->getSymbol();
+ return nullptr;
+}
+
+void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
+ const MCAsmLayout &Layout,
+ const MCFragment *Fragment,
+ const MCFixup &Fixup,
+ MCValue Target,
+ bool &IsPCRel,
+ uint64_t &FixedValue) {
+ const MCSectionData *FixupSection = Fragment->getParent();
+ uint64_t C = Target.getConstant();
+ uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
+
+ if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
+ assert(RefB->getKind() == MCSymbolRefExpr::VK_None &&
+ "Should not have constructed this");
+
+ // Let A, B and C being the components of Target and R be the location of
+ // the fixup. If the fixup is not pcrel, we want to compute (A - B + C).
+ // If it is pcrel, we want to compute (A - B + C - R).
+
+ // In general, ELF has no relocations for -B. It can only represent (A + C)
+ // or (A + C - R). If B = R + K and the relocation is not pcrel, we can
+ // replace B to implement it: (A - R - K + C)
+ if (IsPCRel)
+ Asm.getContext().FatalError(
+ Fixup.getLoc(),
+ "No relocation available to represent this relative expression");
+
+ const MCSymbol &SymB = RefB->getSymbol();
+
+ if (SymB.isUndefined())
+ Asm.getContext().FatalError(
+ Fixup.getLoc(),
+ Twine("symbol '") + SymB.getName() +
+ "' can not be undefined in a subtraction expression");
+
+ assert(!SymB.isAbsolute() && "Should have been folded");
+ const MCSection &SecB = SymB.getSection();
+ if (&SecB != &FixupSection->getSection())
+ Asm.getContext().FatalError(
+ Fixup.getLoc(), "Cannot represent a difference across sections");
+
+ const MCSymbolData &SymBD = Asm.getSymbolData(SymB);
+ uint64_t SymBOffset = Layout.getSymbolOffset(&SymBD);
+ uint64_t K = SymBOffset - FixupOffset;
+ IsPCRel = true;
+ C -= K;
+ }
+
+ // We either rejected the fixup or folded B into C at this point.
+ const MCSymbolRefExpr *RefA = Target.getSymA();
+ const MCSymbol *SymA = RefA ? &RefA->getSymbol() : nullptr;
+ const MCSymbolData *SymAD = SymA ? &Asm.getSymbolData(*SymA) : nullptr;
+
+ unsigned Type = GetRelocType(Target, Fixup, IsPCRel);
+ bool RelocateWithSymbol = shouldRelocateWithSymbol(Asm, RefA, SymAD, C, Type);
+ if (!RelocateWithSymbol && SymA && !SymA->isUndefined())
+ C += Layout.getSymbolOffset(SymAD);
+
+ uint64_t Addend = 0;
+ if (hasRelocationAddend()) {
+ Addend = C;
+ C = 0;
+ }
+
+ FixedValue = C;
+
+ // FIXME: What is this!?!?
+ MCSymbolRefExpr::VariantKind Modifier =
+ RefA ? RefA->getKind() : MCSymbolRefExpr::VK_None;
+ if (RelocNeedsGOT(Modifier))
+ NeedsGOT = true;
+
+ if (!RelocateWithSymbol) {
+ const MCSection *SecA =
+ (SymA && !SymA->isUndefined()) ? &SymA->getSection() : nullptr;
+ const MCSectionData *SecAD = SecA ? &Asm.getSectionData(*SecA) : nullptr;
+ ELFRelocationEntry Rec(FixupOffset, SecAD, Type, Addend);
+ Relocations[FixupSection].push_back(Rec);
+ return;
+ }
+
+ if (SymA) {
+ if (const MCSymbol *R = Renames.lookup(SymA))
+ SymA = R;
+
+ if (const MCSymbol *WeakRef = getWeakRef(*RefA))
+ WeakrefUsedInReloc.insert(WeakRef);
+ else
+ UsedInReloc.insert(SymA);
+ }
+ ELFRelocationEntry Rec(FixupOffset, SymA, Type, Addend);
+ Relocations[FixupSection].push_back(Rec);
+ return;
+}
+
+
+uint64_t
+ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
+ const MCSymbol *S) {
+ const MCSymbolData &SD = Asm.getSymbolData(*S);
+ return SD.getIndex();
+}
+
+bool ELFObjectWriter::isInSymtab(const MCAsmLayout &Layout,
+ const MCSymbolData &Data, bool Used,
+ bool Renamed) {
+ const MCSymbol &Symbol = Data.getSymbol();
+ if (Symbol.isVariable()) {
+ const MCExpr *Expr = Symbol.getVariableValue();
+ if (const MCSymbolRefExpr *Ref = dyn_cast<MCSymbolRefExpr>(Expr)) {
+ if (Ref->getKind() == MCSymbolRefExpr::VK_WEAKREF)
+ return false;
+ }
+ }
+
+ if (Used)
+ return true;
+
+ if (Renamed)
+ return false;
+
+ if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
+ return true;
+
+ if (Symbol.isVariable()) {
+ const MCSymbol *Base = Layout.getBaseSymbol(Symbol);
+ if (Base && Base->isUndefined())
+ return false;
+ }
+
+ bool IsGlobal = MCELF::GetBinding(Data) == ELF::STB_GLOBAL;
+ if (!Symbol.isVariable() && Symbol.isUndefined() && !IsGlobal)
+ return false;
+
+ if (Symbol.isTemporary())
+ return false;
+
+ return true;
+}
+
+bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isUsedInReloc) {
+ if (Data.isExternal())
+ return false;
+
+ const MCSymbol &Symbol = Data.getSymbol();
+ if (Symbol.isDefined())
+ return true;
+
+ if (isUsedInReloc)
+ return false;
+
+ return true;
+}
+
+void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
+ SectionIndexMapTy &SectionIndexMap,
+ const RelMapTy &RelMap) {
+ unsigned Index = 1;
+ for (MCAssembler::iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF &>(it->getSection());
+ if (Section.getType() != ELF::SHT_GROUP)
+ continue;
+ SectionIndexMap[&Section] = Index++;
+ }
+
+ for (MCAssembler::iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF &>(it->getSection());
+ if (Section.getType() == ELF::SHT_GROUP ||
+ Section.getType() == ELF::SHT_REL ||
+ Section.getType() == ELF::SHT_RELA)
+ continue;
+ SectionIndexMap[&Section] = Index++;
+ const MCSectionELF *RelSection = RelMap.lookup(&Section);
+ if (RelSection)
+ SectionIndexMap[RelSection] = Index++;
+ }
+}
+
+void
+ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
+ const SectionIndexMapTy &SectionIndexMap,
+ RevGroupMapTy RevGroupMap,
+ unsigned NumRegularSections) {
+ // FIXME: Is this the correct place to do this?
+ // FIXME: Why is an undefined reference to _GLOBAL_OFFSET_TABLE_ needed?
+ if (NeedsGOT) {
+ StringRef Name = "_GLOBAL_OFFSET_TABLE_";
+ MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name);
+ MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym);
+ Data.setExternal(true);
+ MCELF::SetBinding(Data, ELF::STB_GLOBAL);
+ }
+
+ // Add the data for the symbols.
+ for (MCSymbolData &SD : Asm.symbols()) {
+ const MCSymbol &Symbol = SD.getSymbol();
+
+ bool Used = UsedInReloc.count(&Symbol);
+ bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
+ bool isSignature = RevGroupMap.count(&Symbol);
+
+ if (!isInSymtab(Layout, SD,
+ Used || WeakrefUsed || isSignature,
+ Renames.count(&Symbol)))
+ continue;
+
+ ELFSymbolData MSD;
+ MSD.SymbolData = &SD;
+ const MCSymbol *BaseSymbol = Layout.getBaseSymbol(Symbol);
+
+ // Undefined symbols are global, but this is the first place we
+ // are able to set it.
+ bool Local = isLocal(SD, Used);
+ if (!Local && MCELF::GetBinding(SD) == ELF::STB_LOCAL) {
+ assert(BaseSymbol);
+ MCSymbolData &BaseData = Asm.getSymbolData(*BaseSymbol);
+ MCELF::SetBinding(SD, ELF::STB_GLOBAL);
+ MCELF::SetBinding(BaseData, ELF::STB_GLOBAL);
+ }
+
+ if (!BaseSymbol) {
+ MSD.SectionIndex = ELF::SHN_ABS;
+ } else if (SD.isCommon()) {
+ assert(!Local);
+ MSD.SectionIndex = ELF::SHN_COMMON;
+ } else if (BaseSymbol->isUndefined()) {
+ if (isSignature && !Used)
+ MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
+ else
+ MSD.SectionIndex = ELF::SHN_UNDEF;
+ if (!Used && WeakrefUsed)
+ MCELF::SetBinding(SD, ELF::STB_WEAK);
+ } else {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(BaseSymbol->getSection());
+ MSD.SectionIndex = SectionIndexMap.lookup(&Section);
+ assert(MSD.SectionIndex && "Invalid section index!");
+ }
+
+ // The @@@ in symbol version is replaced with @ in undefined symbols and
+ // @@ in defined ones.
+ StringRef Name = Symbol.getName();
+ SmallString<32> Buf;
+ size_t Pos = Name.find("@@@");
+ if (Pos != StringRef::npos) {
+ Buf += Name.substr(0, Pos);
+ unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
+ Buf += Name.substr(Pos + Skip);
+ Name = Buf;
+ }
+ MSD.Name = StrTabBuilder.add(Name);
+
+ if (MSD.SectionIndex == ELF::SHN_UNDEF)
+ UndefinedSymbolData.push_back(MSD);
+ else if (Local)
+ LocalSymbolData.push_back(MSD);
+ else
+ ExternalSymbolData.push_back(MSD);
+ }
+
+ for (auto i = Asm.file_names_begin(), e = Asm.file_names_end(); i != e; ++i)
+ StrTabBuilder.add(*i);
+
+ StrTabBuilder.finalize();
+
+ for (auto i = Asm.file_names_begin(), e = Asm.file_names_end(); i != e; ++i)
+ FileSymbolData.push_back(StrTabBuilder.getOffset(*i));
+
+ for (ELFSymbolData& MSD : LocalSymbolData)
+ MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name);
+ for (ELFSymbolData& MSD : ExternalSymbolData)
+ MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name);
+ for (ELFSymbolData& MSD : UndefinedSymbolData)
+ MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name);
+
+ // Symbols are required to be in lexicographic order.
+ array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end());
+ array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
+ array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
+
+ // Set the symbol indices. Local symbols must come before all other
+ // symbols with non-local bindings.
+ unsigned Index = FileSymbolData.size() + 1;
+ for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
+ LocalSymbolData[i].SymbolData->setIndex(Index++);
+
+ Index += NumRegularSections;
+
+ for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
+ ExternalSymbolData[i].SymbolData->setIndex(Index++);
+ for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
+ UndefinedSymbolData[i].SymbolData->setIndex(Index++);
+}
+
+void ELFObjectWriter::CreateRelocationSections(MCAssembler &Asm,
+ MCAsmLayout &Layout,
+ RelMapTy &RelMap) {
+ for (MCAssembler::const_iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ const MCSectionData &SD = *it;
+ if (Relocations[&SD].empty())
+ continue;
+
+ MCContext &Ctx = Asm.getContext();
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(SD.getSection());
+
+ const StringRef SectionName = Section.getSectionName();
+ std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel";
+ RelaSectionName += SectionName;
+
+ unsigned EntrySize;
+ if (hasRelocationAddend())
+ EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
+ else
+ EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
+
+ unsigned Flags = 0;
+ StringRef Group = "";
+ if (Section.getFlags() & ELF::SHF_GROUP) {
+ Flags = ELF::SHF_GROUP;
+ Group = Section.getGroup()->getName();
+ }
+
+ const MCSectionELF *RelaSection =
+ Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ?
+ ELF::SHT_RELA : ELF::SHT_REL, Flags,
+ SectionKind::getReadOnly(),
+ EntrySize, Group);
+ RelMap[&Section] = RelaSection;
+ Asm.getOrCreateSectionData(*RelaSection);
+ }
+}
+
+static SmallVector<char, 128>
+getUncompressedData(MCAsmLayout &Layout,
+ MCSectionData::FragmentListType &Fragments) {
+ SmallVector<char, 128> UncompressedData;
+ for (const MCFragment &F : Fragments) {
+ const SmallVectorImpl<char> *Contents;
+ switch (F.getKind()) {
+ case MCFragment::FT_Data:
+ Contents = &cast<MCDataFragment>(F).getContents();
+ break;
+ case MCFragment::FT_Dwarf:
+ Contents = &cast<MCDwarfLineAddrFragment>(F).getContents();
+ break;
+ case MCFragment::FT_DwarfFrame:
+ Contents = &cast<MCDwarfCallFrameFragment>(F).getContents();
+ break;
+ default:
+ llvm_unreachable(
+ "Not expecting any other fragment types in a debug_* section");
+ }
+ UncompressedData.append(Contents->begin(), Contents->end());
+ }
+ return UncompressedData;
+}
+
+// Include the debug info compression header:
+// "ZLIB" followed by 8 bytes representing the uncompressed size of the section,
+// useful for consumers to preallocate a buffer to decompress into.
+static bool
+prependCompressionHeader(uint64_t Size,
+ SmallVectorImpl<char> &CompressedContents) {
+ static const StringRef Magic = "ZLIB";
+ if (Size <= Magic.size() + sizeof(Size) + CompressedContents.size())
+ return false;
+ if (sys::IsLittleEndianHost)
+ sys::swapByteOrder(Size);
+ CompressedContents.insert(CompressedContents.begin(),
+ Magic.size() + sizeof(Size), 0);
+ std::copy(Magic.begin(), Magic.end(), CompressedContents.begin());
+ std::copy(reinterpret_cast<char *>(&Size),
+ reinterpret_cast<char *>(&Size + 1),
+ CompressedContents.begin() + Magic.size());
+ return true;
+}
+
+// Return a single fragment containing the compressed contents of the whole
+// section. Null if the section was not compressed for any reason.
+static std::unique_ptr<MCDataFragment>
+getCompressedFragment(MCAsmLayout &Layout,
+ MCSectionData::FragmentListType &Fragments) {
+ std::unique_ptr<MCDataFragment> CompressedFragment(new MCDataFragment());
+
+ // Gather the uncompressed data from all the fragments, recording the
+ // alignment fragment, if seen, and any fixups.
+ SmallVector<char, 128> UncompressedData =
+ getUncompressedData(Layout, Fragments);
+
+ SmallVectorImpl<char> &CompressedContents = CompressedFragment->getContents();
+
+ zlib::Status Success = zlib::compress(
+ StringRef(UncompressedData.data(), UncompressedData.size()),
+ CompressedContents);
+ if (Success != zlib::StatusOK)
+ return nullptr;
+
+ if (!prependCompressionHeader(UncompressedData.size(), CompressedContents))
+ return nullptr;
+
+ return CompressedFragment;
+}
+
+typedef DenseMap<const MCSectionData *, std::vector<MCSymbolData *>>
+DefiningSymbolMap;
+
+static void UpdateSymbols(const MCAsmLayout &Layout,
+ const std::vector<MCSymbolData *> &Symbols,
+ MCFragment &NewFragment) {
+ for (MCSymbolData *Sym : Symbols) {
+ Sym->setOffset(Sym->getOffset() +
+ Layout.getFragmentOffset(Sym->getFragment()));
+ Sym->setFragment(&NewFragment);
+ }
+}
+
+static void CompressDebugSection(MCAssembler &Asm, MCAsmLayout &Layout,
+ const DefiningSymbolMap &DefiningSymbols,
+ const MCSectionELF &Section,
+ MCSectionData &SD) {
+ StringRef SectionName = Section.getSectionName();
+ MCSectionData::FragmentListType &Fragments = SD.getFragmentList();
+
+ std::unique_ptr<MCDataFragment> CompressedFragment =
+ getCompressedFragment(Layout, Fragments);
+
+ // Leave the section as-is if the fragments could not be compressed.
+ if (!CompressedFragment)
+ return;
+
+ // Update the fragment+offsets of any symbols referring to fragments in this
+ // section to refer to the new fragment.
+ auto I = DefiningSymbols.find(&SD);
+ if (I != DefiningSymbols.end())
+ UpdateSymbols(Layout, I->second, *CompressedFragment);
+
+ // Invalidate the layout for the whole section since it will have new and
+ // different fragments now.
+ Layout.invalidateFragmentsFrom(&Fragments.front());
+ Fragments.clear();
+
+ // Complete the initialization of the new fragment
+ CompressedFragment->setParent(&SD);
+ CompressedFragment->setLayoutOrder(0);
+ Fragments.push_back(CompressedFragment.release());
+
+ // Rename from .debug_* to .zdebug_*
+ Asm.getContext().renameELFSection(&Section,
+ (".z" + SectionName.drop_front(1)).str());
+}
+
+void ELFObjectWriter::CompressDebugSections(MCAssembler &Asm,
+ MCAsmLayout &Layout) {
+ if (!Asm.getContext().getAsmInfo()->compressDebugSections())
+ return;
+
+ DefiningSymbolMap DefiningSymbols;
+
+ for (MCSymbolData &SD : Asm.symbols())
+ if (MCFragment *F = SD.getFragment())
+ DefiningSymbols[F->getParent()].push_back(&SD);
+
+ for (MCSectionData &SD : Asm) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF &>(SD.getSection());
+ StringRef SectionName = Section.getSectionName();
+
+ // Compressing debug_frame requires handling alignment fragments which is
+ // more work (possibly generalizing MCAssembler.cpp:writeFragment to allow
+ // for writing to arbitrary buffers) for little benefit.
+ if (!SectionName.startswith(".debug_") || SectionName == ".debug_frame")
+ continue;
+
+ CompressDebugSection(Asm, Layout, DefiningSymbols, Section, SD);
+ }
+}
+
+void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout,
+ const RelMapTy &RelMap) {
+ for (MCAssembler::const_iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ const MCSectionData &SD = *it;
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(SD.getSection());
+
+ const MCSectionELF *RelaSection = RelMap.lookup(&Section);
+ if (!RelaSection)
+ continue;
+ MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
+ RelaSD.setAlignment(is64Bit() ? 8 : 4);
+
+ MCDataFragment *F = new MCDataFragment(&RelaSD);
+ WriteRelocationsFragment(Asm, F, &*it);
+ }
+}
+
+void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type,
+ uint64_t Flags, uint64_t Address,
+ uint64_t Offset, uint64_t Size,
+ uint32_t Link, uint32_t Info,
+ uint64_t Alignment,
+ uint64_t EntrySize) {
+ Write32(Name); // sh_name: index into string table
+ Write32(Type); // sh_type
+ WriteWord(Flags); // sh_flags
+ WriteWord(Address); // sh_addr
+ WriteWord(Offset); // sh_offset
+ WriteWord(Size); // sh_size
+ Write32(Link); // sh_link
+ Write32(Info); // sh_info
+ WriteWord(Alignment); // sh_addralign
+ WriteWord(EntrySize); // sh_entsize
+}
+
+// ELF doesn't require relocations to be in any order. We sort by the r_offset,
+// just to match gnu as for easier comparison. The use type is an arbitrary way
+// of making the sort deterministic.
+static int cmpRel(const ELFRelocationEntry *AP, const ELFRelocationEntry *BP) {
+ const ELFRelocationEntry &A = *AP;
+ const ELFRelocationEntry &B = *BP;
+ if (A.Offset != B.Offset)
+ return B.Offset - A.Offset;
+ if (B.Type != A.Type)
+ return A.Type - B.Type;
+ llvm_unreachable("ELFRelocs might be unstable!");
+}
+
+static void sortRelocs(const MCAssembler &Asm,
+ std::vector<ELFRelocationEntry> &Relocs) {
+ array_pod_sort(Relocs.begin(), Relocs.end(), cmpRel);
+}
+
+void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
+ MCDataFragment *F,
+ const MCSectionData *SD) {
+ std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
+
+ sortRelocs(Asm, Relocs);
+
+ for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
+ const ELFRelocationEntry &Entry = Relocs[e - i - 1];
+
+ unsigned Index;
+ if (Entry.UseSymbol) {
+ Index = getSymbolIndexInSymbolTable(Asm, Entry.Symbol);
+ } else {
+ const MCSectionData *Sec = Entry.Section;
+ if (Sec)
+ Index = Sec->getOrdinal() + FileSymbolData.size() +
+ LocalSymbolData.size() + 1;
+ else
+ Index = 0;
+ }
+
+ if (is64Bit()) {
+ write(*F, Entry.Offset);
+ if (TargetObjectWriter->isN64()) {
+ write(*F, uint32_t(Index));
+
+ write(*F, TargetObjectWriter->getRSsym(Entry.Type));
+ write(*F, TargetObjectWriter->getRType3(Entry.Type));
+ write(*F, TargetObjectWriter->getRType2(Entry.Type));
+ write(*F, TargetObjectWriter->getRType(Entry.Type));
+ } else {
+ struct ELF::Elf64_Rela ERE64;
+ ERE64.setSymbolAndType(Index, Entry.Type);
+ write(*F, ERE64.r_info);
+ }
+ if (hasRelocationAddend())
+ write(*F, Entry.Addend);
+ } else {
+ write(*F, uint32_t(Entry.Offset));
+
+ struct ELF::Elf32_Rela ERE32;
+ ERE32.setSymbolAndType(Index, Entry.Type);
+ write(*F, ERE32.r_info);
+
+ if (hasRelocationAddend())
+ write(*F, uint32_t(Entry.Addend));
+ }
+ }
+}
+
+void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
+ MCAsmLayout &Layout,
+ SectionIndexMapTy &SectionIndexMap,
+ const RelMapTy &RelMap) {
+ MCContext &Ctx = Asm.getContext();
+ MCDataFragment *F;
+
+ unsigned EntrySize = is64Bit() ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
+
+ // We construct .shstrtab, .symtab and .strtab in this order to match gnu as.
+ const MCSectionELF *ShstrtabSection =
+ Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0,
+ SectionKind::getReadOnly());
+ MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
+ ShstrtabSD.setAlignment(1);
+
+ const MCSectionELF *SymtabSection =
+ Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
+ SectionKind::getReadOnly(),
+ EntrySize, "");
+ MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
+ SymtabSD.setAlignment(is64Bit() ? 8 : 4);
+
+ const MCSectionELF *StrtabSection;
+ StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
+ SectionKind::getReadOnly());
+ MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
+ StrtabSD.setAlignment(1);
+
+ ComputeIndexMap(Asm, SectionIndexMap, RelMap);
+
+ ShstrtabIndex = SectionIndexMap.lookup(ShstrtabSection);
+ SymbolTableIndex = SectionIndexMap.lookup(SymtabSection);
+ StringTableIndex = SectionIndexMap.lookup(StrtabSection);
+
+ // Symbol table
+ F = new MCDataFragment(&SymtabSD);
+ WriteSymbolTable(F, Asm, Layout, SectionIndexMap);
+
+ F = new MCDataFragment(&StrtabSD);
+ F->getContents().append(StrTabBuilder.data().begin(),
+ StrTabBuilder.data().end());
+
+ F = new MCDataFragment(&ShstrtabSD);
+
+ // Section header string table.
+ for (auto it = Asm.begin(), ie = Asm.end(); it != ie; ++it) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(it->getSection());
+ ShStrTabBuilder.add(Section.getSectionName());
+ }
+ ShStrTabBuilder.finalize();
+ F->getContents().append(ShStrTabBuilder.data().begin(),
+ ShStrTabBuilder.data().end());
+}
+
+void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm,
+ MCAsmLayout &Layout,
+ GroupMapTy &GroupMap,
+ RevGroupMapTy &RevGroupMap,
+ SectionIndexMapTy &SectionIndexMap,
+ const RelMapTy &RelMap) {
+ // Create the .note.GNU-stack section if needed.
+ MCContext &Ctx = Asm.getContext();
+ if (Asm.getNoExecStack()) {
+ const MCSectionELF *GnuStackSection =
+ Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS, 0,
+ SectionKind::getReadOnly());
+ Asm.getOrCreateSectionData(*GnuStackSection);
+ }
+
+ // Build the groups
+ for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
+ it != ie; ++it) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(it->getSection());
+ if (!(Section.getFlags() & ELF::SHF_GROUP))
+ continue;
+
+ const MCSymbol *SignatureSymbol = Section.getGroup();
+ Asm.getOrCreateSymbolData(*SignatureSymbol);
+ const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
+ if (!Group) {
+ Group = Ctx.CreateELFGroupSection();
+ MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
+ Data.setAlignment(4);
+ MCDataFragment *F = new MCDataFragment(&Data);
+ write(*F, uint32_t(ELF::GRP_COMDAT));
+ }
+ GroupMap[Group] = SignatureSymbol;
+ }
+
+ ComputeIndexMap(Asm, SectionIndexMap, RelMap);
+
+ // Add sections to the groups
+ for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
+ it != ie; ++it) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(it->getSection());
+ if (!(Section.getFlags() & ELF::SHF_GROUP))
+ continue;
+ const MCSectionELF *Group = RevGroupMap[Section.getGroup()];
+ MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
+ // FIXME: we could use the previous fragment
+ MCDataFragment *F = new MCDataFragment(&Data);
+ uint32_t Index = SectionIndexMap.lookup(&Section);
+ write(*F, Index);
+ }
+}
+
+void ELFObjectWriter::WriteSection(MCAssembler &Asm,
+ const SectionIndexMapTy &SectionIndexMap,
+ uint32_t GroupSymbolIndex,
+ uint64_t Offset, uint64_t Size,
+ uint64_t Alignment,
+ const MCSectionELF &Section) {
+ uint64_t sh_link = 0;
+ uint64_t sh_info = 0;
+
+ switch(Section.getType()) {
+ case ELF::SHT_DYNAMIC:
+ sh_link = ShStrTabBuilder.getOffset(Section.getSectionName());
+ sh_info = 0;
+ break;
+
+ case ELF::SHT_REL:
+ case ELF::SHT_RELA: {
+ const MCSectionELF *SymtabSection;
+ const MCSectionELF *InfoSection;
+ SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB,
+ 0,
+ SectionKind::getReadOnly());
+ sh_link = SectionIndexMap.lookup(SymtabSection);
+ assert(sh_link && ".symtab not found");
+
+ // Remove ".rel" and ".rela" prefixes.
+ unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
+ StringRef SectionName = Section.getSectionName().substr(SecNameLen);
+ StringRef GroupName =
+ Section.getGroup() ? Section.getGroup()->getName() : "";
+
+ InfoSection = Asm.getContext().getELFSection(SectionName, ELF::SHT_PROGBITS,
+ 0, SectionKind::getReadOnly(),
+ 0, GroupName);
+ sh_info = SectionIndexMap.lookup(InfoSection);
+ break;
+ }
+
+ case ELF::SHT_SYMTAB:
+ case ELF::SHT_DYNSYM:
+ sh_link = StringTableIndex;
+ sh_info = LastLocalSymbolIndex;
+ break;
+
+ case ELF::SHT_SYMTAB_SHNDX:
+ sh_link = SymbolTableIndex;
+ break;
+
+ case ELF::SHT_PROGBITS:
+ case ELF::SHT_STRTAB:
+ case ELF::SHT_NOBITS:
+ case ELF::SHT_NOTE:
+ case ELF::SHT_NULL:
+ case ELF::SHT_ARM_ATTRIBUTES:
+ case ELF::SHT_INIT_ARRAY:
+ case ELF::SHT_FINI_ARRAY:
+ case ELF::SHT_PREINIT_ARRAY:
+ case ELF::SHT_X86_64_UNWIND:
+ case ELF::SHT_MIPS_REGINFO:
+ case ELF::SHT_MIPS_OPTIONS:
+ case ELF::SHT_MIPS_ABIFLAGS:
+ // Nothing to do.
+ break;
+
+ case ELF::SHT_GROUP:
+ sh_link = SymbolTableIndex;
+ sh_info = GroupSymbolIndex;
+ break;
+
+ default:
+ llvm_unreachable("FIXME: sh_type value not supported!");
+ }
+
+ if (TargetObjectWriter->getEMachine() == ELF::EM_ARM &&
+ Section.getType() == ELF::SHT_ARM_EXIDX) {
+ StringRef SecName(Section.getSectionName());
+ if (SecName == ".ARM.exidx") {
+ sh_link = SectionIndexMap.lookup(
+ Asm.getContext().getELFSection(".text",
+ ELF::SHT_PROGBITS,
+ ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
+ SectionKind::getText()));
+ } else if (SecName.startswith(".ARM.exidx")) {
+ StringRef GroupName =
+ Section.getGroup() ? Section.getGroup()->getName() : "";
+ sh_link = SectionIndexMap.lookup(Asm.getContext().getELFSection(
+ SecName.substr(sizeof(".ARM.exidx") - 1), ELF::SHT_PROGBITS,
+ ELF::SHF_EXECINSTR | ELF::SHF_ALLOC, SectionKind::getText(), 0,
+ GroupName));
+ }
+ }
+
+ WriteSecHdrEntry(ShStrTabBuilder.getOffset(Section.getSectionName()),
+ Section.getType(),
+ Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
+ Alignment, Section.getEntrySize());
+}
+
+bool ELFObjectWriter::IsELFMetaDataSection(const MCSectionData &SD) {
+ return SD.getOrdinal() == ~UINT32_C(0) &&
+ !SD.getSection().isVirtualSection();
+}
+
+uint64_t ELFObjectWriter::DataSectionSize(const MCSectionData &SD) {
+ uint64_t Ret = 0;
+ for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
+ ++i) {
+ const MCFragment &F = *i;
+ assert(F.getKind() == MCFragment::FT_Data);
+ Ret += cast<MCDataFragment>(F).getContents().size();
+ }
+ return Ret;
+}
+
+uint64_t ELFObjectWriter::GetSectionFileSize(const MCAsmLayout &Layout,
+ const MCSectionData &SD) {
+ if (IsELFMetaDataSection(SD))
+ return DataSectionSize(SD);
+ return Layout.getSectionFileSize(&SD);
+}
+
+uint64_t ELFObjectWriter::GetSectionAddressSize(const MCAsmLayout &Layout,
+ const MCSectionData &SD) {
+ if (IsELFMetaDataSection(SD))
+ return DataSectionSize(SD);
+ return Layout.getSectionAddressSize(&SD);
+}
+
+void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm,
+ const MCAsmLayout &Layout,
+ const MCSectionELF &Section) {
+ const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
+
+ uint64_t Padding = OffsetToAlignment(OS.tell(), SD.getAlignment());
+ WriteZeros(Padding);
+
+ if (IsELFMetaDataSection(SD)) {
+ for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
+ ++i) {
+ const MCFragment &F = *i;
+ assert(F.getKind() == MCFragment::FT_Data);
+ WriteBytes(cast<MCDataFragment>(F).getContents());
+ }
+ } else {
+ Asm.writeSectionData(&SD, Layout);
+ }
+}
+
+void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm,
+ const GroupMapTy &GroupMap,
+ const MCAsmLayout &Layout,
+ const SectionIndexMapTy &SectionIndexMap,
+ const SectionOffsetMapTy &SectionOffsetMap) {
+ const unsigned NumSections = Asm.size() + 1;
+
+ std::vector<const MCSectionELF*> Sections;
+ Sections.resize(NumSections - 1);
+
+ for (SectionIndexMapTy::const_iterator i=
+ SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) {
+ const std::pair<const MCSectionELF*, uint32_t> &p = *i;
+ Sections[p.second - 1] = p.first;
+ }
+
+ // Null section first.
+ uint64_t FirstSectionSize =
+ NumSections >= ELF::SHN_LORESERVE ? NumSections : 0;
+ uint32_t FirstSectionLink =
+ ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0;
+ WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0);
+
+ for (unsigned i = 0; i < NumSections - 1; ++i) {
+ const MCSectionELF &Section = *Sections[i];
+ const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
+ uint32_t GroupSymbolIndex;
+ if (Section.getType() != ELF::SHT_GROUP)
+ GroupSymbolIndex = 0;
+ else
+ GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm,
+ GroupMap.lookup(&Section));
+
+ uint64_t Size = GetSectionAddressSize(Layout, SD);
+
+ WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
+ SectionOffsetMap.lookup(&Section), Size,
+ SD.getAlignment(), Section);
+ }
+}
+
+void ELFObjectWriter::ComputeSectionOrder(MCAssembler &Asm,
+ std::vector<const MCSectionELF*> &Sections) {
+ for (MCAssembler::iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF &>(it->getSection());
+ if (Section.getType() == ELF::SHT_GROUP)
+ Sections.push_back(&Section);
+ }
+
+ for (MCAssembler::iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF &>(it->getSection());
+ if (Section.getType() != ELF::SHT_GROUP &&
+ Section.getType() != ELF::SHT_REL &&
+ Section.getType() != ELF::SHT_RELA)
+ Sections.push_back(&Section);
+ }
+
+ for (MCAssembler::iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF &>(it->getSection());
+ if (Section.getType() == ELF::SHT_REL ||
+ Section.getType() == ELF::SHT_RELA)
+ Sections.push_back(&Section);
+ }
+}
+
+void ELFObjectWriter::WriteObject(MCAssembler &Asm,
+ const MCAsmLayout &Layout) {
+ GroupMapTy GroupMap;
+ RevGroupMapTy RevGroupMap;
+ SectionIndexMapTy SectionIndexMap;
+
+ unsigned NumUserSections = Asm.size();
+
+ CompressDebugSections(Asm, const_cast<MCAsmLayout &>(Layout));
+
+ DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap;
+ CreateRelocationSections(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
+
+ const unsigned NumUserAndRelocSections = Asm.size();
+ CreateIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
+ RevGroupMap, SectionIndexMap, RelMap);
+ const unsigned AllSections = Asm.size();
+ const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections;
+
+ unsigned NumRegularSections = NumUserSections + NumIndexedSections;
+
+ // Compute symbol table information.
+ computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap,
+ NumRegularSections);
+
+ WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
+
+ CreateMetadataSections(const_cast<MCAssembler&>(Asm),
+ const_cast<MCAsmLayout&>(Layout),
+ SectionIndexMap,
+ RelMap);
+
+ uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
+ uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
+ sizeof(ELF::Elf32_Ehdr);
+ uint64_t FileOff = HeaderSize;
+
+ std::vector<const MCSectionELF*> Sections;
+ ComputeSectionOrder(Asm, Sections);
+ unsigned NumSections = Sections.size();
+ SectionOffsetMapTy SectionOffsetMap;
+ for (unsigned i = 0; i < NumRegularSections + 1; ++i) {
+ const MCSectionELF &Section = *Sections[i];
+ const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
+
+ FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
+
+ // Remember the offset into the file for this section.
+ SectionOffsetMap[&Section] = FileOff;
+
+ // Get the size of the section in the output file (including padding).
+ FileOff += GetSectionFileSize(Layout, SD);
+ }
+
+ FileOff = RoundUpToAlignment(FileOff, NaturalAlignment);
+
+ const unsigned SectionHeaderOffset = FileOff - HeaderSize;
+
+ uint64_t SectionHeaderEntrySize = is64Bit() ?
+ sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr);
+ FileOff += (NumSections + 1) * SectionHeaderEntrySize;
+
+ for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) {
+ const MCSectionELF &Section = *Sections[i];
+ const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
+
+ FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
+
+ // Remember the offset into the file for this section.
+ SectionOffsetMap[&Section] = FileOff;
+
+ // Get the size of the section in the output file (including padding).
+ FileOff += GetSectionFileSize(Layout, SD);
+ }
+
+ // Write out the ELF header ...
+ WriteHeader(Asm, SectionHeaderOffset, NumSections + 1);
+
+ // ... then the regular sections ...
+ // + because of .shstrtab
+ for (unsigned i = 0; i < NumRegularSections + 1; ++i)
+ WriteDataSectionData(Asm, Layout, *Sections[i]);
+
+ uint64_t Padding = OffsetToAlignment(OS.tell(), NaturalAlignment);
+ WriteZeros(Padding);
+
+ // ... then the section header table ...
+ WriteSectionHeader(Asm, GroupMap, Layout, SectionIndexMap,
+ SectionOffsetMap);
+
+ // ... and then the remaining sections ...
+ for (unsigned i = NumRegularSections + 1; i < NumSections; ++i)
+ WriteDataSectionData(Asm, Layout, *Sections[i]);
+}
+
+bool
+ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
+ const MCSymbolData &DataA,
+ const MCFragment &FB,
+ bool InSet,
+ bool IsPCRel) const {
+ if (DataA.getFlags() & ELF_STB_Weak || MCELF::GetType(DataA) == ELF::STT_GNU_IFUNC)
+ return false;
+ return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
+ Asm, DataA, FB,InSet, IsPCRel);
+}
+
+MCObjectWriter *llvm::createELFObjectWriter(MCELFObjectTargetWriter *MOTW,
+ raw_ostream &OS,
+ bool IsLittleEndian) {
+ return new ELFObjectWriter(MOTW, OS, IsLittleEndian);
+}
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