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-rw-r--r--contrib/llvm/lib/MC/ELFObjectWriter.cpp973
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diff --git a/contrib/llvm/lib/MC/ELFObjectWriter.cpp 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/ELFObjectWriter.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/MC/MCAssembler.h"
+#include "llvm/MC/MCAsmLayout.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCELFSymbolFlags.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCValue.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/ELF.h"
+#include "llvm/Target/TargetAsmBackend.h"
+
+#include "../Target/X86/X86FixupKinds.h"
+
+#include <vector>
+using namespace llvm;
+
+namespace {
+
+ class ELFObjectWriterImpl {
+ static bool isFixupKindX86PCRel(unsigned Kind) {
+ switch (Kind) {
+ default:
+ return false;
+ case X86::reloc_pcrel_1byte:
+ case X86::reloc_pcrel_4byte:
+ case X86::reloc_riprel_4byte:
+ case X86::reloc_riprel_4byte_movq_load:
+ return true;
+ }
+ }
+
+ /*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;
+
+ // Support lexicographic sorting.
+ bool operator<(const ELFSymbolData &RHS) const {
+ return SymbolData->getSymbol().getName() <
+ RHS.SymbolData->getSymbol().getName();
+ }
+ };
+
+ /// @name Relocation Data
+ /// @{
+
+ struct ELFRelocationEntry {
+ // Make these big enough for both 32-bit and 64-bit
+ uint64_t r_offset;
+ uint64_t r_info;
+ uint64_t r_addend;
+
+ // Support lexicographic sorting.
+ bool operator<(const ELFRelocationEntry &RE) const {
+ return RE.r_offset < r_offset;
+ }
+ };
+
+ llvm::DenseMap<const MCSectionData*,
+ std::vector<ELFRelocationEntry> > Relocations;
+ DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
+
+ /// @}
+ /// @name Symbol Table Data
+ /// @{
+
+ SmallString<256> StringTable;
+ std::vector<ELFSymbolData> LocalSymbolData;
+ std::vector<ELFSymbolData> ExternalSymbolData;
+ std::vector<ELFSymbolData> UndefinedSymbolData;
+
+ /// @}
+
+ ELFObjectWriter *Writer;
+
+ raw_ostream &OS;
+
+ // This holds the current offset into the object file.
+ size_t FileOff;
+
+ unsigned Is64Bit : 1;
+
+ bool HasRelocationAddend;
+
+ // This holds the symbol table index of the last local symbol.
+ unsigned LastLocalSymbolIndex;
+ // This holds the .strtab section index.
+ unsigned StringTableIndex;
+
+ unsigned ShstrtabIndex;
+
+ public:
+ ELFObjectWriterImpl(ELFObjectWriter *_Writer, bool _Is64Bit,
+ bool _HasRelAddend)
+ : Writer(_Writer), OS(Writer->getStream()), FileOff(0),
+ Is64Bit(_Is64Bit), HasRelocationAddend(_HasRelAddend) {
+ }
+
+ void Write8(uint8_t Value) { Writer->Write8(Value); }
+ void Write16(uint16_t Value) { Writer->Write16(Value); }
+ void Write32(uint32_t Value) { Writer->Write32(Value); }
+ //void Write64(uint64_t Value) { Writer->Write64(Value); }
+ void WriteZeros(unsigned N) { Writer->WriteZeros(N); }
+ //void WriteBytes(StringRef Str, unsigned ZeroFillSize = 0) {
+ // Writer->WriteBytes(Str, ZeroFillSize);
+ //}
+
+ void WriteWord(uint64_t W) {
+ if (Is64Bit)
+ Writer->Write64(W);
+ else
+ Writer->Write32(W);
+ }
+
+ void String8(char *buf, uint8_t Value) {
+ buf[0] = Value;
+ }
+
+ void StringLE16(char *buf, uint16_t Value) {
+ buf[0] = char(Value >> 0);
+ buf[1] = char(Value >> 8);
+ }
+
+ void StringLE32(char *buf, uint32_t Value) {
+ StringLE16(buf, uint16_t(Value >> 0));
+ StringLE16(buf + 2, uint16_t(Value >> 16));
+ }
+
+ void StringLE64(char *buf, uint64_t Value) {
+ StringLE32(buf, uint32_t(Value >> 0));
+ StringLE32(buf + 4, uint32_t(Value >> 32));
+ }
+
+ void StringBE16(char *buf ,uint16_t Value) {
+ buf[0] = char(Value >> 8);
+ buf[1] = char(Value >> 0);
+ }
+
+ void StringBE32(char *buf, uint32_t Value) {
+ StringBE16(buf, uint16_t(Value >> 16));
+ StringBE16(buf + 2, uint16_t(Value >> 0));
+ }
+
+ void StringBE64(char *buf, uint64_t Value) {
+ StringBE32(buf, uint32_t(Value >> 32));
+ StringBE32(buf + 4, uint32_t(Value >> 0));
+ }
+
+ void String16(char *buf, uint16_t Value) {
+ if (Writer->isLittleEndian())
+ StringLE16(buf, Value);
+ else
+ StringBE16(buf, Value);
+ }
+
+ void String32(char *buf, uint32_t Value) {
+ if (Writer->isLittleEndian())
+ StringLE32(buf, Value);
+ else
+ StringBE32(buf, Value);
+ }
+
+ void String64(char *buf, uint64_t Value) {
+ if (Writer->isLittleEndian())
+ StringLE64(buf, Value);
+ else
+ StringBE64(buf, Value);
+ }
+
+ void WriteHeader(uint64_t SectionDataSize, unsigned NumberOfSections);
+
+ void WriteSymbolEntry(MCDataFragment *F, uint64_t name, uint8_t info,
+ uint64_t value, uint64_t size,
+ uint8_t other, uint16_t shndx);
+
+ void WriteSymbol(MCDataFragment *F, ELFSymbolData &MSD,
+ const MCAsmLayout &Layout);
+
+ void WriteSymbolTable(MCDataFragment *F, const MCAssembler &Asm,
+ const MCAsmLayout &Layout);
+
+ void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
+ const MCFragment *Fragment, const MCFixup &Fixup,
+ MCValue Target, uint64_t &FixedValue);
+
+ uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
+ const MCSymbol *S);
+
+ /// ComputeSymbolTable - Compute the symbol table data
+ ///
+ /// \param StringTable [out] - The string table data.
+ /// \param StringIndexMap [out] - Map from symbol names to offsets in the
+ /// string table.
+ void ComputeSymbolTable(MCAssembler &Asm);
+
+ void WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
+ const MCSectionData &SD);
+
+ void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout) {
+ for (MCAssembler::const_iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ WriteRelocation(Asm, Layout, *it);
+ }
+ }
+
+ void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout);
+
+ void ExecutePostLayoutBinding(MCAssembler &Asm) {
+ // Compute symbol table information.
+ ComputeSymbolTable(Asm);
+ }
+
+ 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);
+
+ void WriteObject(const MCAssembler &Asm, const MCAsmLayout &Layout);
+ };
+
+}
+
+// Emit the ELF header.
+void ELFObjectWriterImpl::WriteHeader(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(Writer->isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
+
+ Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION]
+ Write8(ELF::ELFOSABI_LINUX); // e_ident[EI_OSABI]
+ Write8(0); // e_ident[EI_ABIVERSION]
+
+ WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
+
+ Write16(ELF::ET_REL); // e_type
+
+ // FIXME: Make this configurable
+ Write16(Is64Bit ? ELF::EM_X86_64 : ELF::EM_386); // 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
+
+ // FIXME: Make this configurable.
+ Write32(0); // e_flags = whatever the target wants
+
+ // 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
+ Write16(NumberOfSections);
+
+ // e_shstrndx = Section # of '.shstrtab'
+ Write16(ShstrtabIndex);
+}
+
+void ELFObjectWriterImpl::WriteSymbolEntry(MCDataFragment *F, uint64_t name,
+ uint8_t info, uint64_t value,
+ uint64_t size, uint8_t other,
+ uint16_t shndx) {
+ if (Is64Bit) {
+ char buf[8];
+
+ String32(buf, name);
+ F->getContents() += StringRef(buf, 4); // st_name
+
+ String8(buf, info);
+ F->getContents() += StringRef(buf, 1); // st_info
+
+ String8(buf, other);
+ F->getContents() += StringRef(buf, 1); // st_other
+
+ String16(buf, shndx);
+ F->getContents() += StringRef(buf, 2); // st_shndx
+
+ String64(buf, value);
+ F->getContents() += StringRef(buf, 8); // st_value
+
+ String64(buf, size);
+ F->getContents() += StringRef(buf, 8); // st_size
+ } else {
+ char buf[4];
+
+ String32(buf, name);
+ F->getContents() += StringRef(buf, 4); // st_name
+
+ String32(buf, value);
+ F->getContents() += StringRef(buf, 4); // st_value
+
+ String32(buf, size);
+ F->getContents() += StringRef(buf, 4); // st_size
+
+ String8(buf, info);
+ F->getContents() += StringRef(buf, 1); // st_info
+
+ String8(buf, other);
+ F->getContents() += StringRef(buf, 1); // st_other
+
+ String16(buf, shndx);
+ F->getContents() += StringRef(buf, 2); // st_shndx
+ }
+}
+
+void ELFObjectWriterImpl::WriteSymbol(MCDataFragment *F, ELFSymbolData &MSD,
+ const MCAsmLayout &Layout) {
+ MCSymbolData &Data = *MSD.SymbolData;
+ uint8_t Info = (Data.getFlags() & 0xff);
+ uint8_t Other = ((Data.getFlags() & 0xf00) >> ELF_STV_Shift);
+ uint64_t Value = 0;
+ uint64_t Size = 0;
+ const MCExpr *ESize;
+
+ if (Data.isCommon() && Data.isExternal())
+ Value = Data.getCommonAlignment();
+
+ if (!Data.isCommon())
+ if (MCFragment *FF = Data.getFragment())
+ Value = Layout.getSymbolAddress(&Data) -
+ Layout.getSectionAddress(FF->getParent());
+
+ ESize = Data.getSize();
+ if (Data.getSize()) {
+ MCValue Res;
+ if (ESize->getKind() == MCExpr::Binary) {
+ const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(ESize);
+
+ if (BE->EvaluateAsRelocatable(Res, &Layout)) {
+ MCSymbolData &A =
+ Layout.getAssembler().getSymbolData(Res.getSymA()->getSymbol());
+ MCSymbolData &B =
+ Layout.getAssembler().getSymbolData(Res.getSymB()->getSymbol());
+
+ Size = Layout.getSymbolAddress(&A) - Layout.getSymbolAddress(&B);
+ }
+ } else if (ESize->getKind() == MCExpr::Constant) {
+ Size = static_cast<const MCConstantExpr *>(ESize)->getValue();
+ } else {
+ assert(0 && "Unsupported size expression");
+ }
+ }
+
+ // Write out the symbol table entry
+ WriteSymbolEntry(F, MSD.StringIndex, Info, Value,
+ Size, Other, MSD.SectionIndex);
+}
+
+void ELFObjectWriterImpl::WriteSymbolTable(MCDataFragment *F,
+ const MCAssembler &Asm,
+ const MCAsmLayout &Layout) {
+ // The string table must be emitted first because we need the index
+ // into the string table for all the symbol names.
+ assert(StringTable.size() && "Missing string table");
+
+ // FIXME: Make sure the start of the symbol table is aligned.
+
+ // The first entry is the undefined symbol entry.
+ unsigned EntrySize = Is64Bit ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
+ F->getContents().append(EntrySize, '\x00');
+
+ // Write the symbol table entries.
+ LastLocalSymbolIndex = LocalSymbolData.size() + 1;
+ for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) {
+ ELFSymbolData &MSD = LocalSymbolData[i];
+ WriteSymbol(F, MSD, Layout);
+ }
+
+ // Write out a symbol table entry for each section.
+ // leaving out the just added .symtab which is at
+ // the very end
+ unsigned Index = 1;
+ for (MCAssembler::const_iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it, ++Index) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(it->getSection());
+ // Leave out relocations so we don't have indexes within
+ // the relocations messed up
+ if (Section.getType() == ELF::SHT_RELA || Section.getType() == ELF::SHT_REL)
+ continue;
+ if (Index == Asm.size())
+ continue;
+ WriteSymbolEntry(F, 0, ELF::STT_SECTION, 0, 0, ELF::STV_DEFAULT, Index);
+ 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) &&
+ "External symbol requires STB_GLOBAL flag");
+ WriteSymbol(F, MSD, Layout);
+ if (Data.getFlags() & ELF_STB_Local)
+ LastLocalSymbolIndex++;
+ }
+
+ for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) {
+ ELFSymbolData &MSD = UndefinedSymbolData[i];
+ MCSymbolData &Data = *MSD.SymbolData;
+ Data.setFlags(Data.getFlags() | ELF_STB_Global);
+ WriteSymbol(F, MSD, Layout);
+ if (Data.getFlags() & ELF_STB_Local)
+ LastLocalSymbolIndex++;
+ }
+}
+
+// FIXME: this is currently X86/X86_64 only
+void ELFObjectWriterImpl::RecordRelocation(const MCAssembler &Asm,
+ const MCAsmLayout &Layout,
+ const MCFragment *Fragment,
+ const MCFixup &Fixup,
+ MCValue Target,
+ uint64_t &FixedValue) {
+ int64_t Addend = 0;
+ unsigned Index = 0;
+ int64_t Value = Target.getConstant();
+
+ if (!Target.isAbsolute()) {
+ const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
+ MCSymbolData &SD = Asm.getSymbolData(*Symbol);
+ const MCSymbolData *Base = Asm.getAtom(Layout, &SD);
+ MCFragment *F = SD.getFragment();
+
+ if (Base) {
+ if (F && (!Symbol->isInSection() || SD.isCommon()) && !SD.isExternal()) {
+ Index = F->getParent()->getOrdinal() + LocalSymbolData.size() + 1;
+ Value += Layout.getSymbolAddress(&SD);
+ } else
+ Index = getSymbolIndexInSymbolTable(Asm, Symbol);
+ if (Base != &SD)
+ Value += Layout.getSymbolAddress(&SD) - Layout.getSymbolAddress(Base);
+ Addend = Value;
+ // Compensate for the addend on i386.
+ if (Is64Bit)
+ Value = 0;
+ } else {
+ if (F) {
+ // Index of the section in .symtab against this symbol
+ // is being relocated + 2 (empty section + abs. symbols).
+ Index = F->getParent()->getOrdinal() + LocalSymbolData.size() + 1;
+
+ MCSectionData *FSD = F->getParent();
+ // Offset of the symbol in the section
+ Addend = Layout.getSymbolAddress(&SD) - Layout.getSectionAddress(FSD);
+ } else {
+ FixedValue = Value;
+ return;
+ }
+ }
+ }
+
+ FixedValue = Value;
+
+ // determine the type of the relocation
+ bool IsPCRel = isFixupKindX86PCRel(Fixup.getKind());
+ unsigned Type;
+ if (Is64Bit) {
+ if (IsPCRel) {
+ Type = ELF::R_X86_64_PC32;
+ } else {
+ switch ((unsigned)Fixup.getKind()) {
+ default: llvm_unreachable("invalid fixup kind!");
+ case FK_Data_8: Type = ELF::R_X86_64_64; break;
+ case X86::reloc_pcrel_4byte:
+ case FK_Data_4:
+ // check that the offset fits within a signed long
+ if (isInt<32>(Target.getConstant()))
+ Type = ELF::R_X86_64_32S;
+ else
+ Type = ELF::R_X86_64_32;
+ break;
+ case FK_Data_2: Type = ELF::R_X86_64_16; break;
+ case X86::reloc_pcrel_1byte:
+ case FK_Data_1: Type = ELF::R_X86_64_8; break;
+ }
+ }
+ } else {
+ if (IsPCRel) {
+ Type = ELF::R_386_PC32;
+ } else {
+ switch ((unsigned)Fixup.getKind()) {
+ default: llvm_unreachable("invalid fixup kind!");
+ case X86::reloc_pcrel_4byte:
+ case FK_Data_4: Type = ELF::R_386_32; break;
+ case FK_Data_2: Type = ELF::R_386_16; break;
+ case X86::reloc_pcrel_1byte:
+ case FK_Data_1: Type = ELF::R_386_8; break;
+ }
+ }
+ }
+
+ ELFRelocationEntry ERE;
+
+ if (Is64Bit) {
+ struct ELF::Elf64_Rela ERE64;
+ ERE64.setSymbolAndType(Index, Type);
+ ERE.r_info = ERE64.r_info;
+ } else {
+ struct ELF::Elf32_Rela ERE32;
+ ERE32.setSymbolAndType(Index, Type);
+ ERE.r_info = ERE32.r_info;
+ }
+
+ ERE.r_offset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
+
+ if (HasRelocationAddend)
+ ERE.r_addend = Addend;
+ else
+ ERE.r_addend = 0; // Silence compiler warning.
+
+ Relocations[Fragment->getParent()].push_back(ERE);
+}
+
+uint64_t
+ELFObjectWriterImpl::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
+ const MCSymbol *S) {
+ MCSymbolData &SD = Asm.getSymbolData(*S);
+
+ // Local symbol.
+ if (!SD.isExternal() && !S->isUndefined())
+ return SD.getIndex() + /* empty symbol */ 1;
+
+ // External or undefined symbol.
+ return SD.getIndex() + Asm.size() + /* empty symbol */ 1;
+}
+
+void ELFObjectWriterImpl::ComputeSymbolTable(MCAssembler &Asm) {
+ // Build section lookup table.
+ DenseMap<const MCSection*, uint8_t> SectionIndexMap;
+ unsigned Index = 1;
+ for (MCAssembler::iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it, ++Index)
+ SectionIndexMap[&it->getSection()] = Index;
+
+ // Index 0 is always the empty string.
+ StringMap<uint64_t> StringIndexMap;
+ StringTable += '\x00';
+
+ // Add the data for local symbols.
+ for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
+ ie = Asm.symbol_end(); it != ie; ++it) {
+ const MCSymbol &Symbol = it->getSymbol();
+
+ // Ignore non-linker visible symbols.
+ if (!Asm.isSymbolLinkerVisible(Symbol))
+ continue;
+
+ if (it->isExternal() || Symbol.isUndefined())
+ continue;
+
+ uint64_t &Entry = StringIndexMap[Symbol.getName()];
+ if (!Entry) {
+ Entry = StringTable.size();
+ StringTable += Symbol.getName();
+ StringTable += '\x00';
+ }
+
+ ELFSymbolData MSD;
+ MSD.SymbolData = it;
+ MSD.StringIndex = Entry;
+
+ if (Symbol.isAbsolute()) {
+ MSD.SectionIndex = ELF::SHN_ABS;
+ LocalSymbolData.push_back(MSD);
+ } else {
+ MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
+ assert(MSD.SectionIndex && "Invalid section index!");
+ LocalSymbolData.push_back(MSD);
+ }
+ }
+
+ // Now add non-local symbols.
+ for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
+ ie = Asm.symbol_end(); it != ie; ++it) {
+ const MCSymbol &Symbol = it->getSymbol();
+
+ // Ignore non-linker visible symbols.
+ if (!Asm.isSymbolLinkerVisible(Symbol))
+ continue;
+
+ if (!it->isExternal() && !Symbol.isUndefined())
+ continue;
+
+ uint64_t &Entry = StringIndexMap[Symbol.getName()];
+ if (!Entry) {
+ Entry = StringTable.size();
+ StringTable += Symbol.getName();
+ StringTable += '\x00';
+ }
+
+ ELFSymbolData MSD;
+ MSD.SymbolData = it;
+ MSD.StringIndex = Entry;
+
+ if (Symbol.isUndefined()) {
+ MSD.SectionIndex = ELF::SHN_UNDEF;
+ // XXX: for some reason we dont Emit* this
+ it->setFlags(it->getFlags() | ELF_STB_Global);
+ UndefinedSymbolData.push_back(MSD);
+ } else if (Symbol.isAbsolute()) {
+ MSD.SectionIndex = ELF::SHN_ABS;
+ ExternalSymbolData.push_back(MSD);
+ } else if (it->isCommon()) {
+ MSD.SectionIndex = ELF::SHN_COMMON;
+ ExternalSymbolData.push_back(MSD);
+ } else {
+ MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
+ assert(MSD.SectionIndex && "Invalid section index!");
+ ExternalSymbolData.push_back(MSD);
+ }
+ }
+
+ // 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.
+ Index = 0;
+ for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
+ LocalSymbolData[i].SymbolData->setIndex(Index++);
+ 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 ELFObjectWriterImpl::WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
+ const MCSectionData &SD) {
+ if (!Relocations[&SD].empty()) {
+ MCContext &Ctx = Asm.getContext();
+ const MCSection *RelaSection;
+ 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);
+
+ RelaSection = Ctx.getELFSection(RelaSectionName, HasRelocationAddend ?
+ ELF::SHT_RELA : ELF::SHT_REL, 0,
+ SectionKind::getReadOnly(),
+ false, EntrySize);
+
+ MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
+ RelaSD.setAlignment(1);
+
+ MCDataFragment *F = new MCDataFragment(&RelaSD);
+
+ WriteRelocationsFragment(Asm, F, &SD);
+
+ Asm.AddSectionToTheEnd(RelaSD, Layout);
+ }
+}
+
+void ELFObjectWriterImpl::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
+}
+
+void ELFObjectWriterImpl::WriteRelocationsFragment(const MCAssembler &Asm,
+ MCDataFragment *F,
+ const MCSectionData *SD) {
+ std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
+ // sort by the r_offset just like gnu as does
+ array_pod_sort(Relocs.begin(), Relocs.end());
+
+ for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
+ ELFRelocationEntry entry = Relocs[e - i - 1];
+
+ unsigned WordSize = Is64Bit ? 8 : 4;
+ F->getContents() += StringRef((const char *)&entry.r_offset, WordSize);
+ F->getContents() += StringRef((const char *)&entry.r_info, WordSize);
+
+ if (HasRelocationAddend)
+ F->getContents() += StringRef((const char *)&entry.r_addend, WordSize);
+ }
+}
+
+void ELFObjectWriterImpl::CreateMetadataSections(MCAssembler &Asm,
+ MCAsmLayout &Layout) {
+ MCContext &Ctx = Asm.getContext();
+ MCDataFragment *F;
+
+ WriteRelocations(Asm, Layout);
+
+ const MCSection *SymtabSection;
+ unsigned EntrySize = Is64Bit ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
+
+ SymtabSection = Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
+ SectionKind::getReadOnly(),
+ false, EntrySize);
+
+ MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
+
+ SymtabSD.setAlignment(Is64Bit ? 8 : 4);
+
+ F = new MCDataFragment(&SymtabSD);
+
+ // Symbol table
+ WriteSymbolTable(F, Asm, Layout);
+ Asm.AddSectionToTheEnd(SymtabSD, Layout);
+
+ const MCSection *StrtabSection;
+ StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
+ SectionKind::getReadOnly(), false);
+
+ MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
+ StrtabSD.setAlignment(1);
+
+ // FIXME: This isn't right. If the sections get rearranged this will
+ // be wrong. We need a proper lookup.
+ StringTableIndex = Asm.size();
+
+ F = new MCDataFragment(&StrtabSD);
+ F->getContents().append(StringTable.begin(), StringTable.end());
+ Asm.AddSectionToTheEnd(StrtabSD, Layout);
+
+ const MCSection *ShstrtabSection;
+ ShstrtabSection = Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0,
+ SectionKind::getReadOnly(), false);
+
+ MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
+ ShstrtabSD.setAlignment(1);
+
+ F = new MCDataFragment(&ShstrtabSD);
+
+ // FIXME: This isn't right. If the sections get rearranged this will
+ // be wrong. We need a proper lookup.
+ ShstrtabIndex = Asm.size();
+
+ // Section header string table.
+ //
+ // The first entry of a string table holds a null character so skip
+ // section 0.
+ uint64_t Index = 1;
+ F->getContents() += '\x00';
+
+ for (MCAssembler::const_iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF&>(it->getSection());
+
+ // Remember the index into the string table so we can write it
+ // into the sh_name field of the section header table.
+ SectionStringTableIndex[&it->getSection()] = Index;
+
+ Index += Section.getSectionName().size() + 1;
+ F->getContents() += Section.getSectionName();
+ F->getContents() += '\x00';
+ }
+
+ Asm.AddSectionToTheEnd(ShstrtabSD, Layout);
+}
+
+void ELFObjectWriterImpl::WriteObject(const MCAssembler &Asm,
+ const MCAsmLayout &Layout) {
+ CreateMetadataSections(const_cast<MCAssembler&>(Asm),
+ const_cast<MCAsmLayout&>(Layout));
+
+ // Add 1 for the null section.
+ unsigned NumSections = Asm.size() + 1;
+
+ uint64_t SectionDataSize = 0;
+
+ for (MCAssembler::const_iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ const MCSectionData &SD = *it;
+
+ // Get the size of the section in the output file (including padding).
+ uint64_t Size = Layout.getSectionFileSize(&SD);
+ SectionDataSize += Size;
+ }
+
+ // Write out the ELF header ...
+ WriteHeader(SectionDataSize, NumSections);
+ FileOff = Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr);
+
+ // ... then all of the sections ...
+ DenseMap<const MCSection*, uint64_t> SectionOffsetMap;
+
+ DenseMap<const MCSection*, uint8_t> SectionIndexMap;
+
+ unsigned Index = 1;
+ for (MCAssembler::const_iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ // Remember the offset into the file for this section.
+ SectionOffsetMap[&it->getSection()] = FileOff;
+
+ SectionIndexMap[&it->getSection()] = Index++;
+
+ const MCSectionData &SD = *it;
+ FileOff += Layout.getSectionFileSize(&SD);
+
+ Asm.WriteSectionData(it, Layout, Writer);
+ }
+
+ // ... and then the section header table.
+ // Should we align the section header table?
+ //
+ // Null section first.
+ WriteSecHdrEntry(0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
+
+ 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());
+
+ uint64_t sh_link = 0;
+ uint64_t sh_info = 0;
+
+ switch(Section.getType()) {
+ case ELF::SHT_DYNAMIC:
+ sh_link = SectionStringTableIndex[&it->getSection()];
+ sh_info = 0;
+ break;
+
+ case ELF::SHT_REL:
+ case ELF::SHT_RELA: {
+ const MCSection *SymtabSection;
+ const MCSection *InfoSection;
+
+ SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
+ SectionKind::getReadOnly(),
+ false);
+ sh_link = SectionIndexMap[SymtabSection];
+
+ // Remove ".rel" and ".rela" prefixes.
+ unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
+ StringRef SectionName = Section.getSectionName().substr(SecNameLen);
+
+ InfoSection = Asm.getContext().getELFSection(SectionName,
+ ELF::SHT_PROGBITS, 0,
+ SectionKind::getReadOnly(),
+ false);
+ sh_info = SectionIndexMap[InfoSection];
+ break;
+ }
+
+ case ELF::SHT_SYMTAB:
+ case ELF::SHT_DYNSYM:
+ sh_link = StringTableIndex;
+ sh_info = LastLocalSymbolIndex;
+ break;
+
+ case ELF::SHT_PROGBITS:
+ case ELF::SHT_STRTAB:
+ case ELF::SHT_NOBITS:
+ case ELF::SHT_NULL:
+ // Nothing to do.
+ break;
+
+ case ELF::SHT_HASH:
+ case ELF::SHT_GROUP:
+ case ELF::SHT_SYMTAB_SHNDX:
+ default:
+ assert(0 && "FIXME: sh_type value not supported!");
+ break;
+ }
+
+ WriteSecHdrEntry(SectionStringTableIndex[&it->getSection()],
+ Section.getType(), Section.getFlags(),
+ Layout.getSectionAddress(&SD),
+ SectionOffsetMap.lookup(&SD.getSection()),
+ Layout.getSectionSize(&SD), sh_link,
+ sh_info, SD.getAlignment(),
+ Section.getEntrySize());
+ }
+}
+
+ELFObjectWriter::ELFObjectWriter(raw_ostream &OS,
+ bool Is64Bit,
+ bool IsLittleEndian,
+ bool HasRelocationAddend)
+ : MCObjectWriter(OS, IsLittleEndian)
+{
+ Impl = new ELFObjectWriterImpl(this, Is64Bit, HasRelocationAddend);
+}
+
+ELFObjectWriter::~ELFObjectWriter() {
+ delete (ELFObjectWriterImpl*) Impl;
+}
+
+void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm) {
+ ((ELFObjectWriterImpl*) Impl)->ExecutePostLayoutBinding(Asm);
+}
+
+void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
+ const MCAsmLayout &Layout,
+ const MCFragment *Fragment,
+ const MCFixup &Fixup, MCValue Target,
+ uint64_t &FixedValue) {
+ ((ELFObjectWriterImpl*) Impl)->RecordRelocation(Asm, Layout, Fragment, Fixup,
+ Target, FixedValue);
+}
+
+void ELFObjectWriter::WriteObject(const MCAssembler &Asm,
+ const MCAsmLayout &Layout) {
+ ((ELFObjectWriterImpl*) Impl)->WriteObject(Asm, Layout);
+}
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