1 //===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements ELF object file writer information.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/ADT/SmallPtrSet.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/StringMap.h"
17 #include "llvm/ADT/Twine.h"
18 #include "llvm/MC/MCAssembler.h"
19 #include "llvm/MC/MCAsmLayout.h"
20 #include "llvm/MC/MCContext.h"
21 #include "llvm/MC/MCELFSymbolFlags.h"
22 #include "llvm/MC/MCExpr.h"
23 #include "llvm/MC/MCObjectWriter.h"
24 #include "llvm/MC/MCSectionELF.h"
25 #include "llvm/MC/MCSymbol.h"
26 #include "llvm/MC/MCValue.h"
27 #include "llvm/Support/Debug.h"
28 #include "llvm/Support/ErrorHandling.h"
29 #include "llvm/Support/ELF.h"
30 #include "llvm/Target/TargetAsmBackend.h"
32 #include "../Target/X86/X86FixupKinds.h"
33 #include "../Target/ARM/ARMFixupKinds.h"
38 static unsigned GetType(const MCSymbolData &SD) {
39 uint32_t Type = (SD.getFlags() & (0xf << ELF_STT_Shift)) >> ELF_STT_Shift;
40 assert(Type == ELF::STT_NOTYPE || Type == ELF::STT_OBJECT ||
41 Type == ELF::STT_FUNC || Type == ELF::STT_SECTION ||
42 Type == ELF::STT_FILE || Type == ELF::STT_COMMON ||
43 Type == ELF::STT_TLS);
47 static unsigned GetBinding(const MCSymbolData &SD) {
48 uint32_t Binding = (SD.getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift;
49 assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
50 Binding == ELF::STB_WEAK);
54 static void SetBinding(MCSymbolData &SD, unsigned Binding) {
55 assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
56 Binding == ELF::STB_WEAK);
57 uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STB_Shift);
58 SD.setFlags(OtherFlags | (Binding << ELF_STB_Shift));
61 static unsigned GetVisibility(MCSymbolData &SD) {
63 (SD.getFlags() & (0xf << ELF_STV_Shift)) >> ELF_STV_Shift;
64 assert(Visibility == ELF::STV_DEFAULT || Visibility == ELF::STV_INTERNAL ||
65 Visibility == ELF::STV_HIDDEN || Visibility == ELF::STV_PROTECTED);
70 static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) {
74 case MCSymbolRefExpr::VK_GOT:
75 case MCSymbolRefExpr::VK_PLT:
76 case MCSymbolRefExpr::VK_GOTPCREL:
77 case MCSymbolRefExpr::VK_TPOFF:
78 case MCSymbolRefExpr::VK_TLSGD:
79 case MCSymbolRefExpr::VK_GOTTPOFF:
80 case MCSymbolRefExpr::VK_INDNTPOFF:
81 case MCSymbolRefExpr::VK_NTPOFF:
82 case MCSymbolRefExpr::VK_GOTNTPOFF:
83 case MCSymbolRefExpr::VK_TLSLDM:
84 case MCSymbolRefExpr::VK_DTPOFF:
85 case MCSymbolRefExpr::VK_TLSLD:
91 class ELFObjectWriter : public MCObjectWriter {
93 /*static bool isFixupKindX86RIPRel(unsigned Kind) {
94 return Kind == X86::reloc_riprel_4byte ||
95 Kind == X86::reloc_riprel_4byte_movq_load;
99 /// ELFSymbolData - Helper struct for containing some precomputed information
101 struct ELFSymbolData {
102 MCSymbolData *SymbolData;
103 uint64_t StringIndex;
104 uint32_t SectionIndex;
106 // Support lexicographic sorting.
107 bool operator<(const ELFSymbolData &RHS) const {
108 if (GetType(*SymbolData) == ELF::STT_FILE)
110 if (GetType(*RHS.SymbolData) == ELF::STT_FILE)
112 return SymbolData->getSymbol().getName() <
113 RHS.SymbolData->getSymbol().getName();
117 /// @name Relocation Data
120 struct ELFRelocationEntry {
121 // Make these big enough for both 32-bit and 64-bit
125 const MCSymbol *Symbol;
129 : r_offset(0), Index(0), Type(0), Symbol(0), r_addend(0) {}
131 ELFRelocationEntry(uint64_t RelocOffset, int Idx,
132 unsigned RelType, const MCSymbol *Sym,
134 : r_offset(RelocOffset), Index(Idx), Type(RelType),
135 Symbol(Sym), r_addend(Addend) {}
137 // Support lexicographic sorting.
138 bool operator<(const ELFRelocationEntry &RE) const {
139 return RE.r_offset < r_offset;
143 SmallPtrSet<const MCSymbol *, 16> UsedInReloc;
144 SmallPtrSet<const MCSymbol *, 16> WeakrefUsedInReloc;
145 DenseMap<const MCSymbol *, const MCSymbol *> Renames;
147 llvm::DenseMap<const MCSectionData*,
148 std::vector<ELFRelocationEntry> > Relocations;
149 DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
152 /// @name Symbol Table Data
155 SmallString<256> StringTable;
156 std::vector<ELFSymbolData> LocalSymbolData;
157 std::vector<ELFSymbolData> ExternalSymbolData;
158 std::vector<ELFSymbolData> UndefinedSymbolData;
164 bool NeedsSymtabShndx;
166 unsigned Is64Bit : 1;
168 bool HasRelocationAddend;
170 Triple::OSType OSType;
174 // This holds the symbol table index of the last local symbol.
175 unsigned LastLocalSymbolIndex;
176 // This holds the .strtab section index.
177 unsigned StringTableIndex;
178 // This holds the .symtab section index.
179 unsigned SymbolTableIndex;
181 unsigned ShstrtabIndex;
184 const MCSymbol *SymbolToReloc(const MCAssembler &Asm,
185 const MCValue &Target,
186 const MCFragment &F) const;
189 ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
190 uint16_t _EMachine, bool _HasRelAddend,
191 Triple::OSType _OSType)
192 : MCObjectWriter(_OS, IsLittleEndian),
193 NeedsGOT(false), NeedsSymtabShndx(false),
194 Is64Bit(_Is64Bit), HasRelocationAddend(_HasRelAddend),
195 OSType(_OSType), EMachine(_EMachine) {
198 virtual ~ELFObjectWriter();
200 void WriteWord(uint64_t W) {
207 void StringLE16(char *buf, uint16_t Value) {
208 buf[0] = char(Value >> 0);
209 buf[1] = char(Value >> 8);
212 void StringLE32(char *buf, uint32_t Value) {
213 StringLE16(buf, uint16_t(Value >> 0));
214 StringLE16(buf + 2, uint16_t(Value >> 16));
217 void StringLE64(char *buf, uint64_t Value) {
218 StringLE32(buf, uint32_t(Value >> 0));
219 StringLE32(buf + 4, uint32_t(Value >> 32));
222 void StringBE16(char *buf ,uint16_t Value) {
223 buf[0] = char(Value >> 8);
224 buf[1] = char(Value >> 0);
227 void StringBE32(char *buf, uint32_t Value) {
228 StringBE16(buf, uint16_t(Value >> 16));
229 StringBE16(buf + 2, uint16_t(Value >> 0));
232 void StringBE64(char *buf, uint64_t Value) {
233 StringBE32(buf, uint32_t(Value >> 32));
234 StringBE32(buf + 4, uint32_t(Value >> 0));
237 void String8(MCDataFragment &F, uint8_t Value) {
240 F.getContents() += StringRef(buf, 1);
243 void String16(MCDataFragment &F, uint16_t Value) {
245 if (isLittleEndian())
246 StringLE16(buf, Value);
248 StringBE16(buf, Value);
249 F.getContents() += StringRef(buf, 2);
252 void String32(MCDataFragment &F, uint32_t Value) {
254 if (isLittleEndian())
255 StringLE32(buf, Value);
257 StringBE32(buf, Value);
258 F.getContents() += StringRef(buf, 4);
261 void String64(MCDataFragment &F, uint64_t Value) {
263 if (isLittleEndian())
264 StringLE64(buf, Value);
266 StringBE64(buf, Value);
267 F.getContents() += StringRef(buf, 8);
270 virtual void WriteHeader(uint64_t SectionDataSize, unsigned NumberOfSections);
272 virtual void WriteSymbolEntry(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
273 uint64_t name, uint8_t info,
274 uint64_t value, uint64_t size,
275 uint8_t other, uint32_t shndx,
278 virtual void WriteSymbol(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
280 const MCAsmLayout &Layout);
282 typedef DenseMap<const MCSectionELF*, uint32_t> SectionIndexMapTy;
283 virtual void WriteSymbolTable(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
284 const MCAssembler &Asm,
285 const MCAsmLayout &Layout,
286 const SectionIndexMapTy &SectionIndexMap);
288 virtual void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
289 const MCFragment *Fragment, const MCFixup &Fixup,
290 MCValue Target, uint64_t &FixedValue);
292 virtual uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
295 // Map from a group section to the signature symbol
296 typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
297 // Map from a signature symbol to the group section
298 typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
300 /// ComputeSymbolTable - Compute the symbol table data
302 /// \param StringTable [out] - The string table data.
303 /// \param StringIndexMap [out] - Map from symbol names to offsets in the
305 virtual void ComputeSymbolTable(MCAssembler &Asm,
306 const SectionIndexMapTy &SectionIndexMap,
307 RevGroupMapTy RevGroupMap);
309 virtual void ComputeIndexMap(MCAssembler &Asm,
310 SectionIndexMapTy &SectionIndexMap);
312 virtual void WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
313 const MCSectionData &SD);
315 virtual void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout) {
316 for (MCAssembler::const_iterator it = Asm.begin(),
317 ie = Asm.end(); it != ie; ++it) {
318 WriteRelocation(Asm, Layout, *it);
322 virtual void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
323 const SectionIndexMapTy &SectionIndexMap);
325 virtual void CreateGroupSections(MCAssembler &Asm, MCAsmLayout &Layout,
326 GroupMapTy &GroupMap, RevGroupMapTy &RevGroupMap);
328 virtual void ExecutePostLayoutBinding(MCAssembler &Asm);
330 virtual void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
331 uint64_t Address, uint64_t Offset,
332 uint64_t Size, uint32_t Link, uint32_t Info,
333 uint64_t Alignment, uint64_t EntrySize);
335 virtual void WriteRelocationsFragment(const MCAssembler &Asm, MCDataFragment *F,
336 const MCSectionData *SD);
338 virtual bool IsFixupFullyResolved(const MCAssembler &Asm,
339 const MCValue Target,
341 const MCFragment *DF) const;
343 virtual void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
344 virtual void WriteSection(MCAssembler &Asm,
345 const SectionIndexMapTy &SectionIndexMap,
346 uint32_t GroupSymbolIndex,
347 uint64_t Offset, uint64_t Size, uint64_t Alignment,
348 const MCSectionELF &Section);
351 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
352 bool IsPCRel, bool IsRelocWithSymbol,
355 virtual bool isFixupKindPCRel(unsigned Kind) const = 0;
358 //===- X86ELFObjectWriter -------------------------------------------===//
360 class X86ELFObjectWriter : public ELFObjectWriter {
362 X86ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
363 uint16_t _EMachine, bool _HasRelAddend,
364 Triple::OSType _OSType);
366 virtual ~X86ELFObjectWriter();
368 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
369 bool IsPCRel, bool IsRelocWithSymbol,
372 virtual bool isFixupKindPCRel(unsigned Kind) const {
379 case X86::reloc_riprel_4byte:
380 case X86::reloc_riprel_4byte_movq_load:
387 //===- ARMELFObjectWriter -------------------------------------------===//
389 class ARMELFObjectWriter : public ELFObjectWriter {
391 ARMELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
392 uint16_t _EMachine, bool _HasRelAddend,
393 Triple::OSType _OSType);
395 virtual ~ARMELFObjectWriter();
397 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
398 bool IsPCRel, bool IsRelocWithSymbol,
400 virtual bool isFixupKindPCRel(unsigned Kind) const {
407 case ARM::fixup_arm_ldst_pcrel_12:
408 case ARM::fixup_arm_pcrel_10:
409 case ARM::fixup_arm_branch:
415 //===- MBlazeELFObjectWriter -------------------------------------------===//
417 class MBlazeELFObjectWriter : public ELFObjectWriter {
419 MBlazeELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
420 uint16_t _EMachine, bool _HasRelAddend,
421 Triple::OSType _OSType);
423 virtual ~MBlazeELFObjectWriter();
425 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
426 bool IsPCRel, bool IsRelocWithSymbol,
429 virtual bool isFixupKindPCRel(unsigned Kind) const {
442 ELFObjectWriter::~ELFObjectWriter()
445 // Emit the ELF header.
446 void ELFObjectWriter::WriteHeader(uint64_t SectionDataSize,
447 unsigned NumberOfSections) {
453 // emitWord method behaves differently for ELF32 and ELF64, writing
454 // 4 bytes in the former and 8 in the latter.
456 Write8(0x7f); // e_ident[EI_MAG0]
457 Write8('E'); // e_ident[EI_MAG1]
458 Write8('L'); // e_ident[EI_MAG2]
459 Write8('F'); // e_ident[EI_MAG3]
461 Write8(Is64Bit ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
464 Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
466 Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION]
469 case Triple::FreeBSD: Write8(ELF::ELFOSABI_FREEBSD); break;
470 case Triple::Linux: Write8(ELF::ELFOSABI_LINUX); break;
471 default: Write8(ELF::ELFOSABI_NONE); break;
473 Write8(0); // e_ident[EI_ABIVERSION]
475 WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
477 Write16(ELF::ET_REL); // e_type
479 Write16(EMachine); // e_machine = target
481 Write32(ELF::EV_CURRENT); // e_version
482 WriteWord(0); // e_entry, no entry point in .o file
483 WriteWord(0); // e_phoff, no program header for .o
484 WriteWord(SectionDataSize + (Is64Bit ? sizeof(ELF::Elf64_Ehdr) :
485 sizeof(ELF::Elf32_Ehdr))); // e_shoff = sec hdr table off in bytes
487 // FIXME: Make this configurable.
488 Write32(0); // e_flags = whatever the target wants
490 // e_ehsize = ELF header size
491 Write16(Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr));
493 Write16(0); // e_phentsize = prog header entry size
494 Write16(0); // e_phnum = # prog header entries = 0
496 // e_shentsize = Section header entry size
497 Write16(Is64Bit ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr));
499 // e_shnum = # of section header ents
500 if (NumberOfSections >= ELF::SHN_LORESERVE)
503 Write16(NumberOfSections);
505 // e_shstrndx = Section # of '.shstrtab'
506 if (NumberOfSections >= ELF::SHN_LORESERVE)
507 Write16(ELF::SHN_XINDEX);
509 Write16(ShstrtabIndex);
512 void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF,
513 MCDataFragment *ShndxF,
515 uint8_t info, uint64_t value,
516 uint64_t size, uint8_t other,
520 if (shndx >= ELF::SHN_LORESERVE && !Reserved)
521 String32(*ShndxF, shndx);
523 String32(*ShndxF, 0);
526 uint16_t Index = (shndx >= ELF::SHN_LORESERVE && !Reserved) ?
527 uint16_t(ELF::SHN_XINDEX) : shndx;
530 String32(*SymtabF, name); // st_name
531 String8(*SymtabF, info); // st_info
532 String8(*SymtabF, other); // st_other
533 String16(*SymtabF, Index); // st_shndx
534 String64(*SymtabF, value); // st_value
535 String64(*SymtabF, size); // st_size
537 String32(*SymtabF, name); // st_name
538 String32(*SymtabF, value); // st_value
539 String32(*SymtabF, size); // st_size
540 String8(*SymtabF, info); // st_info
541 String8(*SymtabF, other); // st_other
542 String16(*SymtabF, Index); // st_shndx
546 static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout) {
547 if (Data.isCommon() && Data.isExternal())
548 return Data.getCommonAlignment();
550 const MCSymbol &Symbol = Data.getSymbol();
551 if (!Symbol.isInSection())
554 if (Data.getFragment())
555 return Layout.getSymbolOffset(&Data);
560 void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm) {
561 // The presence of symbol versions causes undefined symbols and
562 // versions declared with @@@ to be renamed.
564 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
565 ie = Asm.symbol_end(); it != ie; ++it) {
566 const MCSymbol &Alias = it->getSymbol();
567 const MCSymbol &Symbol = Alias.AliasedSymbol();
568 MCSymbolData &SD = Asm.getSymbolData(Symbol);
571 if (&Symbol == &Alias)
574 StringRef AliasName = Alias.getName();
575 size_t Pos = AliasName.find('@');
576 if (Pos == StringRef::npos)
579 // Aliases defined with .symvar copy the binding from the symbol they alias.
580 // This is the first place we are able to copy this information.
581 it->setExternal(SD.isExternal());
582 SetBinding(*it, GetBinding(SD));
584 StringRef Rest = AliasName.substr(Pos);
585 if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
588 // FIXME: produce a better error message.
589 if (Symbol.isUndefined() && Rest.startswith("@@") &&
590 !Rest.startswith("@@@"))
591 report_fatal_error("A @@ version cannot be undefined");
593 Renames.insert(std::make_pair(&Symbol, &Alias));
597 void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
598 MCDataFragment *ShndxF,
600 const MCAsmLayout &Layout) {
601 MCSymbolData &OrigData = *MSD.SymbolData;
603 Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
605 bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
606 Data.getSymbol().isVariable();
608 uint8_t Binding = GetBinding(OrigData);
609 uint8_t Visibility = GetVisibility(OrigData);
610 uint8_t Type = GetType(Data);
612 uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
613 uint8_t Other = Visibility;
615 uint64_t Value = SymbolValue(Data, Layout);
619 assert(!(Data.isCommon() && !Data.isExternal()));
621 ESize = Data.getSize();
622 if (Data.getSize()) {
624 if (ESize->getKind() == MCExpr::Binary) {
625 const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(ESize);
627 if (BE->EvaluateAsRelocatable(Res, &Layout)) {
628 assert(!Res.getSymA() || !Res.getSymA()->getSymbol().isDefined());
629 assert(!Res.getSymB() || !Res.getSymB()->getSymbol().isDefined());
630 Size = Res.getConstant();
632 } else if (ESize->getKind() == MCExpr::Constant) {
633 Size = static_cast<const MCConstantExpr *>(ESize)->getValue();
635 assert(0 && "Unsupported size expression");
639 // Write out the symbol table entry
640 WriteSymbolEntry(SymtabF, ShndxF, MSD.StringIndex, Info, Value,
641 Size, Other, MSD.SectionIndex, IsReserved);
644 void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
645 MCDataFragment *ShndxF,
646 const MCAssembler &Asm,
647 const MCAsmLayout &Layout,
648 const SectionIndexMapTy &SectionIndexMap) {
649 // The string table must be emitted first because we need the index
650 // into the string table for all the symbol names.
651 assert(StringTable.size() && "Missing string table");
653 // FIXME: Make sure the start of the symbol table is aligned.
655 // The first entry is the undefined symbol entry.
656 WriteSymbolEntry(SymtabF, ShndxF, 0, 0, 0, 0, 0, 0, false);
658 // Write the symbol table entries.
659 LastLocalSymbolIndex = LocalSymbolData.size() + 1;
660 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) {
661 ELFSymbolData &MSD = LocalSymbolData[i];
662 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
665 // Write out a symbol table entry for each regular section.
666 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e;
668 const MCSectionELF &Section =
669 static_cast<const MCSectionELF&>(i->getSection());
670 if (Section.getType() == ELF::SHT_RELA ||
671 Section.getType() == ELF::SHT_REL ||
672 Section.getType() == ELF::SHT_STRTAB ||
673 Section.getType() == ELF::SHT_SYMTAB)
675 WriteSymbolEntry(SymtabF, ShndxF, 0, ELF::STT_SECTION, 0, 0,
676 ELF::STV_DEFAULT, SectionIndexMap.lookup(&Section), false);
677 LastLocalSymbolIndex++;
680 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) {
681 ELFSymbolData &MSD = ExternalSymbolData[i];
682 MCSymbolData &Data = *MSD.SymbolData;
683 assert(((Data.getFlags() & ELF_STB_Global) ||
684 (Data.getFlags() & ELF_STB_Weak)) &&
685 "External symbol requires STB_GLOBAL or STB_WEAK flag");
686 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
687 if (GetBinding(Data) == ELF::STB_LOCAL)
688 LastLocalSymbolIndex++;
691 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) {
692 ELFSymbolData &MSD = UndefinedSymbolData[i];
693 MCSymbolData &Data = *MSD.SymbolData;
694 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
695 if (GetBinding(Data) == ELF::STB_LOCAL)
696 LastLocalSymbolIndex++;
700 const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
701 const MCValue &Target,
702 const MCFragment &F) const {
703 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
704 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
705 const MCSymbol *Renamed = Renames.lookup(&Symbol);
706 const MCSymbolData &SD = Asm.getSymbolData(Symbol);
708 if (ASymbol.isUndefined()) {
714 if (SD.isExternal()) {
720 const MCSectionELF &Section =
721 static_cast<const MCSectionELF&>(ASymbol.getSection());
722 const SectionKind secKind = Section.getKind();
727 if (secKind.isThreadLocal()) {
733 MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
734 const MCSectionELF &Sec2 =
735 static_cast<const MCSectionELF&>(F.getParent()->getSection());
737 if (&Sec2 != &Section &&
738 (Kind == MCSymbolRefExpr::VK_PLT ||
739 Kind == MCSymbolRefExpr::VK_GOTPCREL ||
740 Kind == MCSymbolRefExpr::VK_GOTOFF)) {
746 if (Section.getFlags() & MCSectionELF::SHF_MERGE) {
747 if (Target.getConstant() == 0)
758 void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
759 const MCAsmLayout &Layout,
760 const MCFragment *Fragment,
761 const MCFixup &Fixup,
763 uint64_t &FixedValue) {
766 int64_t Value = Target.getConstant();
767 const MCSymbol *RelocSymbol = NULL;
769 bool IsPCRel = isFixupKindPCRel(Fixup.getKind());
770 if (!Target.isAbsolute()) {
771 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
772 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
773 RelocSymbol = SymbolToReloc(Asm, Target, *Fragment);
775 if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
776 const MCSymbol &SymbolB = RefB->getSymbol();
777 MCSymbolData &SDB = Asm.getSymbolData(SymbolB);
780 // Offset of the symbol in the section
781 int64_t a = Layout.getSymbolOffset(&SDB);
783 // Ofeset of the relocation in the section
784 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
789 MCSymbolData &SD = Asm.getSymbolData(ASymbol);
790 MCFragment *F = SD.getFragment();
792 Index = F->getParent()->getOrdinal() + 1;
794 // Offset of the symbol in the section
795 Value += Layout.getSymbolOffset(&SD);
797 if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
798 WeakrefUsedInReloc.insert(RelocSymbol);
800 UsedInReloc.insert(RelocSymbol);
804 // Compensate for the addend on i386.
810 unsigned Type = GetRelocType(Target, Fixup, IsPCRel,
811 (RelocSymbol != 0), Addend);
813 uint64_t RelocOffset = Layout.getFragmentOffset(Fragment) +
816 if (!HasRelocationAddend) Addend = 0;
817 ELFRelocationEntry ERE(RelocOffset, Index, Type, RelocSymbol, Addend);
818 Relocations[Fragment->getParent()].push_back(ERE);
823 ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
825 MCSymbolData &SD = Asm.getSymbolData(*S);
826 return SD.getIndex();
829 static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
830 bool Used, bool Renamed) {
831 if (Data.getFlags() & ELF_Other_Weakref)
840 const MCSymbol &Symbol = Data.getSymbol();
842 if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
845 const MCSymbol &A = Symbol.AliasedSymbol();
846 if (!A.isVariable() && A.isUndefined() && !Data.isCommon())
849 if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
852 if (Symbol.isTemporary())
858 static bool isLocal(const MCSymbolData &Data, bool isSignature,
859 bool isUsedInReloc) {
860 if (Data.isExternal())
863 const MCSymbol &Symbol = Data.getSymbol();
864 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
866 if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
867 if (isSignature && !isUsedInReloc)
876 void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
877 SectionIndexMapTy &SectionIndexMap) {
879 for (MCAssembler::iterator it = Asm.begin(),
880 ie = Asm.end(); it != ie; ++it) {
881 const MCSectionELF &Section =
882 static_cast<const MCSectionELF &>(it->getSection());
883 if (Section.getType() != ELF::SHT_GROUP)
885 SectionIndexMap[&Section] = Index++;
888 for (MCAssembler::iterator it = Asm.begin(),
889 ie = Asm.end(); it != ie; ++it) {
890 const MCSectionELF &Section =
891 static_cast<const MCSectionELF &>(it->getSection());
892 if (Section.getType() == ELF::SHT_GROUP)
894 SectionIndexMap[&Section] = Index++;
898 void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
899 const SectionIndexMapTy &SectionIndexMap,
900 RevGroupMapTy RevGroupMap) {
901 // FIXME: Is this the correct place to do this?
903 llvm::StringRef Name = "_GLOBAL_OFFSET_TABLE_";
904 MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name);
905 MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym);
906 Data.setExternal(true);
907 SetBinding(Data, ELF::STB_GLOBAL);
910 // Build section lookup table.
911 int NumRegularSections = Asm.size();
913 // Index 0 is always the empty string.
914 StringMap<uint64_t> StringIndexMap;
915 StringTable += '\x00';
917 // Add the data for the symbols.
918 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
919 ie = Asm.symbol_end(); it != ie; ++it) {
920 const MCSymbol &Symbol = it->getSymbol();
922 bool Used = UsedInReloc.count(&Symbol);
923 bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
924 bool isSignature = RevGroupMap.count(&Symbol);
926 if (!isInSymtab(Asm, *it,
927 Used || WeakrefUsed || isSignature,
928 Renames.count(&Symbol)))
933 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
935 // Undefined symbols are global, but this is the first place we
936 // are able to set it.
937 bool Local = isLocal(*it, isSignature, Used);
938 if (!Local && GetBinding(*it) == ELF::STB_LOCAL) {
939 MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
940 SetBinding(*it, ELF::STB_GLOBAL);
941 SetBinding(SD, ELF::STB_GLOBAL);
944 if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
945 SetBinding(*it, ELF::STB_WEAK);
947 if (it->isCommon()) {
949 MSD.SectionIndex = ELF::SHN_COMMON;
950 } else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
951 MSD.SectionIndex = ELF::SHN_ABS;
952 } else if (RefSymbol.isUndefined()) {
953 if (isSignature && !Used)
954 MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
956 MSD.SectionIndex = ELF::SHN_UNDEF;
958 const MCSectionELF &Section =
959 static_cast<const MCSectionELF&>(RefSymbol.getSection());
960 MSD.SectionIndex = SectionIndexMap.lookup(&Section);
961 if (MSD.SectionIndex >= ELF::SHN_LORESERVE)
962 NeedsSymtabShndx = true;
963 assert(MSD.SectionIndex && "Invalid section index!");
966 // The @@@ in symbol version is replaced with @ in undefined symbols and
967 // @@ in defined ones.
968 StringRef Name = Symbol.getName();
971 size_t Pos = Name.find("@@@");
972 if (Pos != StringRef::npos) {
973 Buf += Name.substr(0, Pos);
974 unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
975 Buf += Name.substr(Pos + Skip);
979 uint64_t &Entry = StringIndexMap[Name];
981 Entry = StringTable.size();
983 StringTable += '\x00';
985 MSD.StringIndex = Entry;
986 if (MSD.SectionIndex == ELF::SHN_UNDEF)
987 UndefinedSymbolData.push_back(MSD);
989 LocalSymbolData.push_back(MSD);
991 ExternalSymbolData.push_back(MSD);
994 // Symbols are required to be in lexicographic order.
995 array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end());
996 array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
997 array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
999 // Set the symbol indices. Local symbols must come before all other
1000 // symbols with non-local bindings.
1002 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
1003 LocalSymbolData[i].SymbolData->setIndex(Index++);
1005 Index += NumRegularSections;
1007 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
1008 ExternalSymbolData[i].SymbolData->setIndex(Index++);
1009 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
1010 UndefinedSymbolData[i].SymbolData->setIndex(Index++);
1013 void ELFObjectWriter::WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
1014 const MCSectionData &SD) {
1015 if (!Relocations[&SD].empty()) {
1016 MCContext &Ctx = Asm.getContext();
1017 const MCSectionELF *RelaSection;
1018 const MCSectionELF &Section =
1019 static_cast<const MCSectionELF&>(SD.getSection());
1021 const StringRef SectionName = Section.getSectionName();
1022 std::string RelaSectionName = HasRelocationAddend ? ".rela" : ".rel";
1023 RelaSectionName += SectionName;
1026 if (HasRelocationAddend)
1027 EntrySize = Is64Bit ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
1029 EntrySize = Is64Bit ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
1031 RelaSection = Ctx.getELFSection(RelaSectionName, HasRelocationAddend ?
1032 ELF::SHT_RELA : ELF::SHT_REL, 0,
1033 SectionKind::getReadOnly(),
1036 MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
1037 RelaSD.setAlignment(Is64Bit ? 8 : 4);
1039 MCDataFragment *F = new MCDataFragment(&RelaSD);
1041 WriteRelocationsFragment(Asm, F, &SD);
1045 void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type,
1046 uint64_t Flags, uint64_t Address,
1047 uint64_t Offset, uint64_t Size,
1048 uint32_t Link, uint32_t Info,
1050 uint64_t EntrySize) {
1051 Write32(Name); // sh_name: index into string table
1052 Write32(Type); // sh_type
1053 WriteWord(Flags); // sh_flags
1054 WriteWord(Address); // sh_addr
1055 WriteWord(Offset); // sh_offset
1056 WriteWord(Size); // sh_size
1057 Write32(Link); // sh_link
1058 Write32(Info); // sh_info
1059 WriteWord(Alignment); // sh_addralign
1060 WriteWord(EntrySize); // sh_entsize
1063 void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
1065 const MCSectionData *SD) {
1066 std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
1067 // sort by the r_offset just like gnu as does
1068 array_pod_sort(Relocs.begin(), Relocs.end());
1070 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
1071 ELFRelocationEntry entry = Relocs[e - i - 1];
1075 else if (entry.Index < 0)
1076 entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol);
1078 entry.Index += LocalSymbolData.size();
1080 String64(*F, entry.r_offset);
1082 struct ELF::Elf64_Rela ERE64;
1083 ERE64.setSymbolAndType(entry.Index, entry.Type);
1084 String64(*F, ERE64.r_info);
1086 if (HasRelocationAddend)
1087 String64(*F, entry.r_addend);
1089 String32(*F, entry.r_offset);
1091 struct ELF::Elf32_Rela ERE32;
1092 ERE32.setSymbolAndType(entry.Index, entry.Type);
1093 String32(*F, ERE32.r_info);
1095 if (HasRelocationAddend)
1096 String32(*F, entry.r_addend);
1101 void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
1102 MCAsmLayout &Layout,
1103 const SectionIndexMapTy &SectionIndexMap) {
1104 MCContext &Ctx = Asm.getContext();
1107 unsigned EntrySize = Is64Bit ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
1109 // We construct .shstrtab, .symtab and .strtab in this order to match gnu as.
1110 const MCSectionELF *ShstrtabSection =
1111 Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0,
1112 SectionKind::getReadOnly());
1113 MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
1114 ShstrtabSD.setAlignment(1);
1115 ShstrtabIndex = Asm.size();
1117 const MCSectionELF *SymtabSection =
1118 Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
1119 SectionKind::getReadOnly(),
1121 MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
1122 SymtabSD.setAlignment(Is64Bit ? 8 : 4);
1123 SymbolTableIndex = Asm.size();
1125 MCSectionData *SymtabShndxSD = NULL;
1127 if (NeedsSymtabShndx) {
1128 const MCSectionELF *SymtabShndxSection =
1129 Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0,
1130 SectionKind::getReadOnly(), 4, "");
1131 SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection);
1132 SymtabShndxSD->setAlignment(4);
1135 const MCSection *StrtabSection;
1136 StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
1137 SectionKind::getReadOnly());
1138 MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
1139 StrtabSD.setAlignment(1);
1140 StringTableIndex = Asm.size();
1142 WriteRelocations(Asm, Layout);
1145 F = new MCDataFragment(&SymtabSD);
1146 MCDataFragment *ShndxF = NULL;
1147 if (NeedsSymtabShndx) {
1148 ShndxF = new MCDataFragment(SymtabShndxSD);
1150 WriteSymbolTable(F, ShndxF, Asm, Layout, SectionIndexMap);
1152 F = new MCDataFragment(&StrtabSD);
1153 F->getContents().append(StringTable.begin(), StringTable.end());
1155 F = new MCDataFragment(&ShstrtabSD);
1157 // Section header string table.
1159 // The first entry of a string table holds a null character so skip
1162 F->getContents() += '\x00';
1164 StringMap<uint64_t> SecStringMap;
1165 for (MCAssembler::const_iterator it = Asm.begin(),
1166 ie = Asm.end(); it != ie; ++it) {
1167 const MCSectionELF &Section =
1168 static_cast<const MCSectionELF&>(it->getSection());
1169 // FIXME: We could merge suffixes like in .text and .rela.text.
1171 StringRef Name = Section.getSectionName();
1172 if (SecStringMap.count(Name)) {
1173 SectionStringTableIndex[&Section] = SecStringMap[Name];
1176 // Remember the index into the string table so we can write it
1177 // into the sh_name field of the section header table.
1178 SectionStringTableIndex[&Section] = Index;
1179 SecStringMap[Name] = Index;
1181 Index += Name.size() + 1;
1182 F->getContents() += Name;
1183 F->getContents() += '\x00';
1187 bool ELFObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
1188 const MCValue Target,
1190 const MCFragment *DF) const {
1191 // If this is a PCrel relocation, find the section this fixup value is
1193 const MCSection *BaseSection = 0;
1195 BaseSection = &DF->getParent()->getSection();
1196 assert(BaseSection);
1199 const MCSection *SectionA = 0;
1200 const MCSymbol *SymbolA = 0;
1201 if (const MCSymbolRefExpr *A = Target.getSymA()) {
1202 SymbolA = &A->getSymbol();
1203 SectionA = &SymbolA->AliasedSymbol().getSection();
1206 const MCSection *SectionB = 0;
1207 const MCSymbol *SymbolB = 0;
1208 if (const MCSymbolRefExpr *B = Target.getSymB()) {
1209 SymbolB = &B->getSymbol();
1210 SectionB = &SymbolB->AliasedSymbol().getSection();
1214 return SectionA == SectionB;
1219 // Absolute address but PCrel instruction, so we need a relocation.
1223 // FIXME: This is in here just to match gnu as output. If the two ends
1224 // are in the same section, there is nothing that the linker can do to
1226 const MCSymbolData &DataA = Asm.getSymbolData(*SymbolA);
1227 if (DataA.isExternal())
1230 return BaseSection == SectionA;
1233 void ELFObjectWriter::CreateGroupSections(MCAssembler &Asm,
1234 MCAsmLayout &Layout,
1235 GroupMapTy &GroupMap,
1236 RevGroupMapTy &RevGroupMap) {
1238 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1240 const MCSectionELF &Section =
1241 static_cast<const MCSectionELF&>(it->getSection());
1242 if (!(Section.getFlags() & MCSectionELF::SHF_GROUP))
1245 const MCSymbol *SignatureSymbol = Section.getGroup();
1246 Asm.getOrCreateSymbolData(*SignatureSymbol);
1247 const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
1249 Group = Asm.getContext().CreateELFGroupSection();
1250 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1251 Data.setAlignment(4);
1252 MCDataFragment *F = new MCDataFragment(&Data);
1253 String32(*F, ELF::GRP_COMDAT);
1255 GroupMap[Group] = SignatureSymbol;
1258 // Add sections to the groups
1260 unsigned NumGroups = RevGroupMap.size();
1261 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1262 it != ie; ++it, ++Index) {
1263 const MCSectionELF &Section =
1264 static_cast<const MCSectionELF&>(it->getSection());
1265 if (!(Section.getFlags() & MCSectionELF::SHF_GROUP))
1267 const MCSectionELF *Group = RevGroupMap[Section.getGroup()];
1268 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1269 // FIXME: we could use the previous fragment
1270 MCDataFragment *F = new MCDataFragment(&Data);
1271 String32(*F, NumGroups + Index);
1275 void ELFObjectWriter::WriteSection(MCAssembler &Asm,
1276 const SectionIndexMapTy &SectionIndexMap,
1277 uint32_t GroupSymbolIndex,
1278 uint64_t Offset, uint64_t Size,
1280 const MCSectionELF &Section) {
1281 uint64_t sh_link = 0;
1282 uint64_t sh_info = 0;
1284 switch(Section.getType()) {
1285 case ELF::SHT_DYNAMIC:
1286 sh_link = SectionStringTableIndex[&Section];
1291 case ELF::SHT_RELA: {
1292 const MCSectionELF *SymtabSection;
1293 const MCSectionELF *InfoSection;
1294 SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB,
1296 SectionKind::getReadOnly());
1297 sh_link = SectionIndexMap.lookup(SymtabSection);
1298 assert(sh_link && ".symtab not found");
1300 // Remove ".rel" and ".rela" prefixes.
1301 unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
1302 StringRef SectionName = Section.getSectionName().substr(SecNameLen);
1304 InfoSection = Asm.getContext().getELFSection(SectionName,
1305 ELF::SHT_PROGBITS, 0,
1306 SectionKind::getReadOnly());
1307 sh_info = SectionIndexMap.lookup(InfoSection);
1311 case ELF::SHT_SYMTAB:
1312 case ELF::SHT_DYNSYM:
1313 sh_link = StringTableIndex;
1314 sh_info = LastLocalSymbolIndex;
1317 case ELF::SHT_SYMTAB_SHNDX:
1318 sh_link = SymbolTableIndex;
1321 case ELF::SHT_PROGBITS:
1322 case ELF::SHT_STRTAB:
1323 case ELF::SHT_NOBITS:
1325 case ELF::SHT_ARM_ATTRIBUTES:
1329 case ELF::SHT_GROUP: {
1330 sh_link = SymbolTableIndex;
1331 sh_info = GroupSymbolIndex;
1336 assert(0 && "FIXME: sh_type value not supported!");
1340 WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(),
1341 Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
1342 Alignment, Section.getEntrySize());
1345 static bool IsELFMetaDataSection(const MCSectionData &SD) {
1346 return SD.getOrdinal() == ~UINT32_C(0) &&
1347 !SD.getSection().isVirtualSection();
1350 static uint64_t DataSectionSize(const MCSectionData &SD) {
1352 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1354 const MCFragment &F = *i;
1355 assert(F.getKind() == MCFragment::FT_Data);
1356 Ret += cast<MCDataFragment>(F).getContents().size();
1361 static uint64_t GetSectionFileSize(const MCAsmLayout &Layout,
1362 const MCSectionData &SD) {
1363 if (IsELFMetaDataSection(SD))
1364 return DataSectionSize(SD);
1365 return Layout.getSectionFileSize(&SD);
1368 static uint64_t GetSectionSize(const MCAsmLayout &Layout,
1369 const MCSectionData &SD) {
1370 if (IsELFMetaDataSection(SD))
1371 return DataSectionSize(SD);
1372 return Layout.getSectionSize(&SD);
1375 static void WriteDataSectionData(ELFObjectWriter *W, const MCSectionData &SD) {
1376 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1378 const MCFragment &F = *i;
1379 assert(F.getKind() == MCFragment::FT_Data);
1380 W->WriteBytes(cast<MCDataFragment>(F).getContents().str());
1384 void ELFObjectWriter::WriteObject(MCAssembler &Asm,
1385 const MCAsmLayout &Layout) {
1386 GroupMapTy GroupMap;
1387 RevGroupMapTy RevGroupMap;
1388 CreateGroupSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
1391 SectionIndexMapTy SectionIndexMap;
1393 ComputeIndexMap(Asm, SectionIndexMap);
1395 // Compute symbol table information.
1396 ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap);
1398 CreateMetadataSections(const_cast<MCAssembler&>(Asm),
1399 const_cast<MCAsmLayout&>(Layout),
1402 // Update to include the metadata sections.
1403 ComputeIndexMap(Asm, SectionIndexMap);
1405 // Add 1 for the null section.
1406 unsigned NumSections = Asm.size() + 1;
1407 uint64_t NaturalAlignment = Is64Bit ? 8 : 4;
1408 uint64_t HeaderSize = Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr);
1409 uint64_t FileOff = HeaderSize;
1411 std::vector<const MCSectionELF*> Sections;
1412 Sections.resize(NumSections);
1414 for (SectionIndexMapTy::const_iterator i=
1415 SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) {
1416 const std::pair<const MCSectionELF*, uint32_t> &p = *i;
1417 Sections[p.second] = p.first;
1420 for (unsigned i = 1; i < NumSections; ++i) {
1421 const MCSectionELF &Section = *Sections[i];
1422 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1424 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
1426 // Get the size of the section in the output file (including padding).
1427 FileOff += GetSectionFileSize(Layout, SD);
1430 FileOff = RoundUpToAlignment(FileOff, NaturalAlignment);
1432 // Write out the ELF header ...
1433 WriteHeader(FileOff - HeaderSize, NumSections);
1435 FileOff = HeaderSize;
1437 // ... then all of the sections ...
1438 DenseMap<const MCSection*, uint64_t> SectionOffsetMap;
1440 for (unsigned i = 1; i < NumSections; ++i) {
1441 const MCSectionELF &Section = *Sections[i];
1442 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1444 uint64_t Padding = OffsetToAlignment(FileOff, SD.getAlignment());
1445 WriteZeros(Padding);
1448 // Remember the offset into the file for this section.
1449 SectionOffsetMap[&Section] = FileOff;
1451 FileOff += GetSectionFileSize(Layout, SD);
1453 if (IsELFMetaDataSection(SD))
1454 WriteDataSectionData(this, SD);
1456 Asm.WriteSectionData(&SD, Layout, this);
1459 uint64_t Padding = OffsetToAlignment(FileOff, NaturalAlignment);
1460 WriteZeros(Padding);
1463 // ... and then the section header table.
1464 // Should we align the section header table?
1466 // Null section first.
1467 uint64_t FirstSectionSize =
1468 NumSections >= ELF::SHN_LORESERVE ? NumSections : 0;
1469 uint32_t FirstSectionLink =
1470 ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0;
1471 WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0);
1473 for (unsigned i = 1; i < NumSections; ++i) {
1474 const MCSectionELF &Section = *Sections[i];
1475 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1476 uint32_t GroupSymbolIndex;
1477 if (Section.getType() != ELF::SHT_GROUP)
1478 GroupSymbolIndex = 0;
1480 GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm, GroupMap[&Section]);
1482 uint64_t Size = GetSectionSize(Layout, SD);
1484 WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
1485 SectionOffsetMap[&Section], Size,
1486 SD.getAlignment(), Section);
1490 MCObjectWriter *llvm::createELFObjectWriter(raw_ostream &OS,
1492 Triple::OSType OSType,
1494 bool IsLittleEndian,
1495 bool HasRelocationAddend) {
1498 case ELF::EM_X86_64:
1499 return new X86ELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
1500 HasRelocationAddend, OSType); break;
1502 return new ARMELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
1503 HasRelocationAddend, OSType); break;
1504 case ELF::EM_MBLAZE:
1505 return new MBlazeELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
1506 HasRelocationAddend, OSType); break;
1507 default: llvm_unreachable("Unsupported architecture"); break;
1512 /// START OF SUBCLASSES for ELFObjectWriter
1513 //===- ARMELFObjectWriter -------------------------------------------===//
1515 ARMELFObjectWriter::ARMELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
1516 bool _IsLittleEndian,
1517 uint16_t _EMachine, bool _HasRelocationAddend,
1518 Triple::OSType _OSType)
1519 : ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
1520 _HasRelocationAddend, _OSType)
1523 ARMELFObjectWriter::~ARMELFObjectWriter()
1526 unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target,
1527 const MCFixup &Fixup,
1529 bool IsRelocWithSymbol,
1531 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
1532 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
1536 default: assert(0 && "Unimplemented Modifier");
1537 case MCSymbolRefExpr::VK_None: break;
1539 switch ((unsigned)Fixup.getKind()) {
1540 default: assert(0 && "Unimplemented");
1541 case ARM::fixup_arm_branch: return ELF::R_ARM_CALL; break;
1544 switch ((unsigned)Fixup.getKind()) {
1545 default: llvm_unreachable("invalid fixup kind!");
1546 case ARM::fixup_arm_ldst_pcrel_12:
1547 case ARM::fixup_arm_pcrel_10:
1548 case ARM::fixup_arm_adr_pcrel_12:
1549 case ARM::fixup_arm_thumb_bl:
1550 assert(0 && "Unimplemented"); break;
1551 case ARM::fixup_arm_branch:
1552 return ELF::R_ARM_CALL; break;
1553 case ARM::fixup_arm_movt_hi16:
1554 return ELF::R_ARM_MOVT_ABS; break;
1555 case ARM::fixup_arm_movw_lo16:
1556 return ELF::R_ARM_MOVW_ABS_NC; break;
1560 if (RelocNeedsGOT(Modifier))
1565 //===- MBlazeELFObjectWriter -------------------------------------------===//
1567 MBlazeELFObjectWriter::MBlazeELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
1568 bool _IsLittleEndian,
1570 bool _HasRelocationAddend,
1571 Triple::OSType _OSType)
1572 : ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
1573 _HasRelocationAddend, _OSType) {
1576 MBlazeELFObjectWriter::~MBlazeELFObjectWriter() {
1579 unsigned MBlazeELFObjectWriter::GetRelocType(const MCValue &Target,
1580 const MCFixup &Fixup,
1582 bool IsRelocWithSymbol,
1584 // determine the type of the relocation
1587 switch ((unsigned)Fixup.getKind()) {
1589 llvm_unreachable("Unimplemented");
1591 Type = ELF::R_MICROBLAZE_64_PCREL;
1594 Type = ELF::R_MICROBLAZE_32_PCREL;
1598 switch ((unsigned)Fixup.getKind()) {
1599 default: llvm_unreachable("invalid fixup kind!");
1601 Type = ((IsRelocWithSymbol || Addend !=0)
1602 ? ELF::R_MICROBLAZE_32
1603 : ELF::R_MICROBLAZE_64);
1606 Type = ELF::R_MICROBLAZE_32;
1613 //===- X86ELFObjectWriter -------------------------------------------===//
1616 X86ELFObjectWriter::X86ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
1617 bool _IsLittleEndian,
1618 uint16_t _EMachine, bool _HasRelocationAddend,
1619 Triple::OSType _OSType)
1620 : ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
1621 _HasRelocationAddend, _OSType)
1624 X86ELFObjectWriter::~X86ELFObjectWriter()
1627 unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
1628 const MCFixup &Fixup,
1630 bool IsRelocWithSymbol,
1632 // determine the type of the relocation
1634 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
1635 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
1641 llvm_unreachable("Unimplemented");
1642 case MCSymbolRefExpr::VK_None:
1643 Type = ELF::R_X86_64_PC32;
1645 case MCSymbolRefExpr::VK_PLT:
1646 Type = ELF::R_X86_64_PLT32;
1648 case MCSymbolRefExpr::VK_GOTPCREL:
1649 Type = ELF::R_X86_64_GOTPCREL;
1651 case MCSymbolRefExpr::VK_GOTTPOFF:
1652 Type = ELF::R_X86_64_GOTTPOFF;
1654 case MCSymbolRefExpr::VK_TLSGD:
1655 Type = ELF::R_X86_64_TLSGD;
1657 case MCSymbolRefExpr::VK_TLSLD:
1658 Type = ELF::R_X86_64_TLSLD;
1662 switch ((unsigned)Fixup.getKind()) {
1663 default: llvm_unreachable("invalid fixup kind!");
1664 case FK_Data_8: Type = ELF::R_X86_64_64; break;
1665 case X86::reloc_signed_4byte:
1667 assert(isInt<32>(Target.getConstant()));
1670 llvm_unreachable("Unimplemented");
1671 case MCSymbolRefExpr::VK_None:
1672 Type = ELF::R_X86_64_32S;
1674 case MCSymbolRefExpr::VK_GOT:
1675 Type = ELF::R_X86_64_GOT32;
1677 case MCSymbolRefExpr::VK_GOTPCREL:
1678 Type = ELF::R_X86_64_GOTPCREL;
1680 case MCSymbolRefExpr::VK_TPOFF:
1681 Type = ELF::R_X86_64_TPOFF32;
1683 case MCSymbolRefExpr::VK_DTPOFF:
1684 Type = ELF::R_X86_64_DTPOFF32;
1689 Type = ELF::R_X86_64_32;
1691 case FK_Data_2: Type = ELF::R_X86_64_16; break;
1693 case FK_Data_1: Type = ELF::R_X86_64_8; break;
1700 llvm_unreachable("Unimplemented");
1701 case MCSymbolRefExpr::VK_None:
1702 Type = ELF::R_386_PC32;
1704 case MCSymbolRefExpr::VK_PLT:
1705 Type = ELF::R_386_PLT32;
1709 switch ((unsigned)Fixup.getKind()) {
1710 default: llvm_unreachable("invalid fixup kind!");
1712 case X86::reloc_global_offset_table:
1713 Type = ELF::R_386_GOTPC;
1716 // FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode
1718 case X86::reloc_signed_4byte:
1723 llvm_unreachable("Unimplemented");
1724 case MCSymbolRefExpr::VK_None:
1725 Type = ELF::R_386_32;
1727 case MCSymbolRefExpr::VK_GOT:
1728 Type = ELF::R_386_GOT32;
1730 case MCSymbolRefExpr::VK_GOTOFF:
1731 Type = ELF::R_386_GOTOFF;
1733 case MCSymbolRefExpr::VK_TLSGD:
1734 Type = ELF::R_386_TLS_GD;
1736 case MCSymbolRefExpr::VK_TPOFF:
1737 Type = ELF::R_386_TLS_LE_32;
1739 case MCSymbolRefExpr::VK_INDNTPOFF:
1740 Type = ELF::R_386_TLS_IE;
1742 case MCSymbolRefExpr::VK_NTPOFF:
1743 Type = ELF::R_386_TLS_LE;
1745 case MCSymbolRefExpr::VK_GOTNTPOFF:
1746 Type = ELF::R_386_TLS_GOTIE;
1748 case MCSymbolRefExpr::VK_TLSLDM:
1749 Type = ELF::R_386_TLS_LDM;
1751 case MCSymbolRefExpr::VK_DTPOFF:
1752 Type = ELF::R_386_TLS_LDO_32;
1756 case FK_Data_2: Type = ELF::R_386_16; break;
1758 case FK_Data_1: Type = ELF::R_386_8; break;
1763 if (RelocNeedsGOT(Modifier))