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:
90 static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) {
91 const MCFixupKindInfo &FKI =
92 Asm.getBackend().getFixupKindInfo((MCFixupKind) Kind);
94 return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel;
98 class ELFObjectWriter : public MCObjectWriter {
100 /*static bool isFixupKindX86RIPRel(unsigned Kind) {
101 return Kind == X86::reloc_riprel_4byte ||
102 Kind == X86::reloc_riprel_4byte_movq_load;
106 /// ELFSymbolData - Helper struct for containing some precomputed information
108 struct ELFSymbolData {
109 MCSymbolData *SymbolData;
110 uint64_t StringIndex;
111 uint32_t SectionIndex;
113 // Support lexicographic sorting.
114 bool operator<(const ELFSymbolData &RHS) const {
115 if (GetType(*SymbolData) == ELF::STT_FILE)
117 if (GetType(*RHS.SymbolData) == ELF::STT_FILE)
119 return SymbolData->getSymbol().getName() <
120 RHS.SymbolData->getSymbol().getName();
124 /// @name Relocation Data
127 struct ELFRelocationEntry {
128 // Make these big enough for both 32-bit and 64-bit
132 const MCSymbol *Symbol;
136 : r_offset(0), Index(0), Type(0), Symbol(0), r_addend(0) {}
138 ELFRelocationEntry(uint64_t RelocOffset, int Idx,
139 unsigned RelType, const MCSymbol *Sym,
141 : r_offset(RelocOffset), Index(Idx), Type(RelType),
142 Symbol(Sym), r_addend(Addend) {}
144 // Support lexicographic sorting.
145 bool operator<(const ELFRelocationEntry &RE) const {
146 return RE.r_offset < r_offset;
150 SmallPtrSet<const MCSymbol *, 16> UsedInReloc;
151 SmallPtrSet<const MCSymbol *, 16> WeakrefUsedInReloc;
152 DenseMap<const MCSymbol *, const MCSymbol *> Renames;
154 llvm::DenseMap<const MCSectionData*,
155 std::vector<ELFRelocationEntry> > Relocations;
156 DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
159 /// @name Symbol Table Data
162 SmallString<256> StringTable;
163 std::vector<ELFSymbolData> LocalSymbolData;
164 std::vector<ELFSymbolData> ExternalSymbolData;
165 std::vector<ELFSymbolData> UndefinedSymbolData;
171 bool NeedsSymtabShndx;
173 unsigned Is64Bit : 1;
175 bool HasRelocationAddend;
177 Triple::OSType OSType;
181 // This holds the symbol table index of the last local symbol.
182 unsigned LastLocalSymbolIndex;
183 // This holds the .strtab section index.
184 unsigned StringTableIndex;
185 // This holds the .symtab section index.
186 unsigned SymbolTableIndex;
188 unsigned ShstrtabIndex;
191 const MCSymbol *SymbolToReloc(const MCAssembler &Asm,
192 const MCValue &Target,
193 const MCFragment &F) const;
196 ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
197 uint16_t _EMachine, bool _HasRelAddend,
198 Triple::OSType _OSType)
199 : MCObjectWriter(_OS, IsLittleEndian),
200 NeedsGOT(false), NeedsSymtabShndx(false),
201 Is64Bit(_Is64Bit), HasRelocationAddend(_HasRelAddend),
202 OSType(_OSType), EMachine(_EMachine) {
205 virtual ~ELFObjectWriter();
207 void WriteWord(uint64_t W) {
214 void StringLE16(char *buf, uint16_t Value) {
215 buf[0] = char(Value >> 0);
216 buf[1] = char(Value >> 8);
219 void StringLE32(char *buf, uint32_t Value) {
220 StringLE16(buf, uint16_t(Value >> 0));
221 StringLE16(buf + 2, uint16_t(Value >> 16));
224 void StringLE64(char *buf, uint64_t Value) {
225 StringLE32(buf, uint32_t(Value >> 0));
226 StringLE32(buf + 4, uint32_t(Value >> 32));
229 void StringBE16(char *buf ,uint16_t Value) {
230 buf[0] = char(Value >> 8);
231 buf[1] = char(Value >> 0);
234 void StringBE32(char *buf, uint32_t Value) {
235 StringBE16(buf, uint16_t(Value >> 16));
236 StringBE16(buf + 2, uint16_t(Value >> 0));
239 void StringBE64(char *buf, uint64_t Value) {
240 StringBE32(buf, uint32_t(Value >> 32));
241 StringBE32(buf + 4, uint32_t(Value >> 0));
244 void String8(MCDataFragment &F, uint8_t Value) {
247 F.getContents() += StringRef(buf, 1);
250 void String16(MCDataFragment &F, uint16_t Value) {
252 if (isLittleEndian())
253 StringLE16(buf, Value);
255 StringBE16(buf, Value);
256 F.getContents() += StringRef(buf, 2);
259 void String32(MCDataFragment &F, uint32_t Value) {
261 if (isLittleEndian())
262 StringLE32(buf, Value);
264 StringBE32(buf, Value);
265 F.getContents() += StringRef(buf, 4);
268 void String64(MCDataFragment &F, uint64_t Value) {
270 if (isLittleEndian())
271 StringLE64(buf, Value);
273 StringBE64(buf, Value);
274 F.getContents() += StringRef(buf, 8);
277 virtual void WriteHeader(uint64_t SectionDataSize, unsigned NumberOfSections);
279 virtual void WriteSymbolEntry(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
280 uint64_t name, uint8_t info,
281 uint64_t value, uint64_t size,
282 uint8_t other, uint32_t shndx,
285 virtual void WriteSymbol(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
287 const MCAsmLayout &Layout);
289 typedef DenseMap<const MCSectionELF*, uint32_t> SectionIndexMapTy;
290 virtual void WriteSymbolTable(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
291 const MCAssembler &Asm,
292 const MCAsmLayout &Layout,
293 const SectionIndexMapTy &SectionIndexMap);
295 virtual void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
296 const MCFragment *Fragment, const MCFixup &Fixup,
297 MCValue Target, uint64_t &FixedValue);
299 virtual uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
302 // Map from a group section to the signature symbol
303 typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
304 // Map from a signature symbol to the group section
305 typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
307 /// ComputeSymbolTable - Compute the symbol table data
309 /// \param StringTable [out] - The string table data.
310 /// \param StringIndexMap [out] - Map from symbol names to offsets in the
312 virtual void ComputeSymbolTable(MCAssembler &Asm,
313 const SectionIndexMapTy &SectionIndexMap,
314 RevGroupMapTy RevGroupMap);
316 virtual void ComputeIndexMap(MCAssembler &Asm,
317 SectionIndexMapTy &SectionIndexMap);
319 virtual void WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
320 const MCSectionData &SD);
322 virtual void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout) {
323 for (MCAssembler::const_iterator it = Asm.begin(),
324 ie = Asm.end(); it != ie; ++it) {
325 WriteRelocation(Asm, Layout, *it);
329 virtual void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
330 const SectionIndexMapTy &SectionIndexMap);
332 virtual void CreateGroupSections(MCAssembler &Asm, MCAsmLayout &Layout,
333 GroupMapTy &GroupMap, RevGroupMapTy &RevGroupMap);
335 virtual void ExecutePostLayoutBinding(MCAssembler &Asm,
336 const MCAsmLayout &Layout);
338 virtual void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
339 uint64_t Address, uint64_t Offset,
340 uint64_t Size, uint32_t Link, uint32_t Info,
341 uint64_t Alignment, uint64_t EntrySize);
343 virtual void WriteRelocationsFragment(const MCAssembler &Asm,
345 const MCSectionData *SD);
348 IsSymbolRefDifferenceFullyResolved(const MCAssembler &Asm,
349 const MCSymbolRefExpr *A,
350 const MCSymbolRefExpr *B) const {
351 // FIXME: Implement this!
355 virtual bool IsFixupFullyResolved(const MCAssembler &Asm,
356 const MCValue Target,
358 const MCFragment *DF) const;
360 virtual void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
361 virtual void WriteSection(MCAssembler &Asm,
362 const SectionIndexMapTy &SectionIndexMap,
363 uint32_t GroupSymbolIndex,
364 uint64_t Offset, uint64_t Size, uint64_t Alignment,
365 const MCSectionELF &Section);
368 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
369 bool IsPCRel, bool IsRelocWithSymbol,
373 //===- X86ELFObjectWriter -------------------------------------------===//
375 class X86ELFObjectWriter : public ELFObjectWriter {
377 X86ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
378 uint16_t _EMachine, bool _HasRelAddend,
379 Triple::OSType _OSType);
381 virtual ~X86ELFObjectWriter();
383 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
384 bool IsPCRel, bool IsRelocWithSymbol,
389 //===- ARMELFObjectWriter -------------------------------------------===//
391 class ARMELFObjectWriter : public ELFObjectWriter {
393 ARMELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
394 uint16_t _EMachine, bool _HasRelAddend,
395 Triple::OSType _OSType);
397 virtual ~ARMELFObjectWriter();
399 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
400 bool IsPCRel, bool IsRelocWithSymbol,
404 //===- MBlazeELFObjectWriter -------------------------------------------===//
406 class MBlazeELFObjectWriter : public ELFObjectWriter {
408 MBlazeELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
409 uint16_t _EMachine, bool _HasRelAddend,
410 Triple::OSType _OSType);
412 virtual ~MBlazeELFObjectWriter();
414 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
415 bool IsPCRel, bool IsRelocWithSymbol,
420 ELFObjectWriter::~ELFObjectWriter()
423 // Emit the ELF header.
424 void ELFObjectWriter::WriteHeader(uint64_t SectionDataSize,
425 unsigned NumberOfSections) {
431 // emitWord method behaves differently for ELF32 and ELF64, writing
432 // 4 bytes in the former and 8 in the latter.
434 Write8(0x7f); // e_ident[EI_MAG0]
435 Write8('E'); // e_ident[EI_MAG1]
436 Write8('L'); // e_ident[EI_MAG2]
437 Write8('F'); // e_ident[EI_MAG3]
439 Write8(Is64Bit ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
442 Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
444 Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION]
447 case Triple::FreeBSD: Write8(ELF::ELFOSABI_FREEBSD); break;
448 case Triple::Linux: Write8(ELF::ELFOSABI_LINUX); break;
449 default: Write8(ELF::ELFOSABI_NONE); break;
451 Write8(0); // e_ident[EI_ABIVERSION]
453 WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
455 Write16(ELF::ET_REL); // e_type
457 Write16(EMachine); // e_machine = target
459 Write32(ELF::EV_CURRENT); // e_version
460 WriteWord(0); // e_entry, no entry point in .o file
461 WriteWord(0); // e_phoff, no program header for .o
462 WriteWord(SectionDataSize + (Is64Bit ? sizeof(ELF::Elf64_Ehdr) :
463 sizeof(ELF::Elf32_Ehdr))); // e_shoff = sec hdr table off in bytes
465 // FIXME: Make this configurable.
466 Write32(0); // e_flags = whatever the target wants
468 // e_ehsize = ELF header size
469 Write16(Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr));
471 Write16(0); // e_phentsize = prog header entry size
472 Write16(0); // e_phnum = # prog header entries = 0
474 // e_shentsize = Section header entry size
475 Write16(Is64Bit ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr));
477 // e_shnum = # of section header ents
478 if (NumberOfSections >= ELF::SHN_LORESERVE)
481 Write16(NumberOfSections);
483 // e_shstrndx = Section # of '.shstrtab'
484 if (NumberOfSections >= ELF::SHN_LORESERVE)
485 Write16(ELF::SHN_XINDEX);
487 Write16(ShstrtabIndex);
490 void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF,
491 MCDataFragment *ShndxF,
493 uint8_t info, uint64_t value,
494 uint64_t size, uint8_t other,
498 if (shndx >= ELF::SHN_LORESERVE && !Reserved)
499 String32(*ShndxF, shndx);
501 String32(*ShndxF, 0);
504 uint16_t Index = (shndx >= ELF::SHN_LORESERVE && !Reserved) ?
505 uint16_t(ELF::SHN_XINDEX) : shndx;
508 String32(*SymtabF, name); // st_name
509 String8(*SymtabF, info); // st_info
510 String8(*SymtabF, other); // st_other
511 String16(*SymtabF, Index); // st_shndx
512 String64(*SymtabF, value); // st_value
513 String64(*SymtabF, size); // st_size
515 String32(*SymtabF, name); // st_name
516 String32(*SymtabF, value); // st_value
517 String32(*SymtabF, size); // st_size
518 String8(*SymtabF, info); // st_info
519 String8(*SymtabF, other); // st_other
520 String16(*SymtabF, Index); // st_shndx
524 static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout) {
525 if (Data.isCommon() && Data.isExternal())
526 return Data.getCommonAlignment();
528 const MCSymbol &Symbol = Data.getSymbol();
529 if (!Symbol.isInSection())
532 if (Data.getFragment())
533 return Layout.getSymbolOffset(&Data);
538 void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
539 const MCAsmLayout &Layout) {
540 // The presence of symbol versions causes undefined symbols and
541 // versions declared with @@@ to be renamed.
543 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
544 ie = Asm.symbol_end(); it != ie; ++it) {
545 const MCSymbol &Alias = it->getSymbol();
546 const MCSymbol &Symbol = Alias.AliasedSymbol();
547 MCSymbolData &SD = Asm.getSymbolData(Symbol);
550 if (&Symbol == &Alias)
553 StringRef AliasName = Alias.getName();
554 size_t Pos = AliasName.find('@');
555 if (Pos == StringRef::npos)
558 // Aliases defined with .symvar copy the binding from the symbol they alias.
559 // This is the first place we are able to copy this information.
560 it->setExternal(SD.isExternal());
561 SetBinding(*it, GetBinding(SD));
563 StringRef Rest = AliasName.substr(Pos);
564 if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
567 // FIXME: produce a better error message.
568 if (Symbol.isUndefined() && Rest.startswith("@@") &&
569 !Rest.startswith("@@@"))
570 report_fatal_error("A @@ version cannot be undefined");
572 Renames.insert(std::make_pair(&Symbol, &Alias));
576 void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
577 MCDataFragment *ShndxF,
579 const MCAsmLayout &Layout) {
580 MCSymbolData &OrigData = *MSD.SymbolData;
582 Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
584 bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
585 Data.getSymbol().isVariable();
587 uint8_t Binding = GetBinding(OrigData);
588 uint8_t Visibility = GetVisibility(OrigData);
589 uint8_t Type = GetType(Data);
591 uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
592 uint8_t Other = Visibility;
594 uint64_t Value = SymbolValue(Data, Layout);
598 assert(!(Data.isCommon() && !Data.isExternal()));
600 ESize = Data.getSize();
601 if (Data.getSize()) {
603 if (ESize->getKind() == MCExpr::Binary) {
604 const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(ESize);
606 if (BE->EvaluateAsRelocatable(Res, &Layout)) {
607 assert(!Res.getSymA() || !Res.getSymA()->getSymbol().isDefined());
608 assert(!Res.getSymB() || !Res.getSymB()->getSymbol().isDefined());
609 Size = Res.getConstant();
611 } else if (ESize->getKind() == MCExpr::Constant) {
612 Size = static_cast<const MCConstantExpr *>(ESize)->getValue();
614 assert(0 && "Unsupported size expression");
618 // Write out the symbol table entry
619 WriteSymbolEntry(SymtabF, ShndxF, MSD.StringIndex, Info, Value,
620 Size, Other, MSD.SectionIndex, IsReserved);
623 void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
624 MCDataFragment *ShndxF,
625 const MCAssembler &Asm,
626 const MCAsmLayout &Layout,
627 const SectionIndexMapTy &SectionIndexMap) {
628 // The string table must be emitted first because we need the index
629 // into the string table for all the symbol names.
630 assert(StringTable.size() && "Missing string table");
632 // FIXME: Make sure the start of the symbol table is aligned.
634 // The first entry is the undefined symbol entry.
635 WriteSymbolEntry(SymtabF, ShndxF, 0, 0, 0, 0, 0, 0, false);
637 // Write the symbol table entries.
638 LastLocalSymbolIndex = LocalSymbolData.size() + 1;
639 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) {
640 ELFSymbolData &MSD = LocalSymbolData[i];
641 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
644 // Write out a symbol table entry for each regular section.
645 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e;
647 const MCSectionELF &Section =
648 static_cast<const MCSectionELF&>(i->getSection());
649 if (Section.getType() == ELF::SHT_RELA ||
650 Section.getType() == ELF::SHT_REL ||
651 Section.getType() == ELF::SHT_STRTAB ||
652 Section.getType() == ELF::SHT_SYMTAB)
654 WriteSymbolEntry(SymtabF, ShndxF, 0, ELF::STT_SECTION, 0, 0,
655 ELF::STV_DEFAULT, SectionIndexMap.lookup(&Section), false);
656 LastLocalSymbolIndex++;
659 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) {
660 ELFSymbolData &MSD = ExternalSymbolData[i];
661 MCSymbolData &Data = *MSD.SymbolData;
662 assert(((Data.getFlags() & ELF_STB_Global) ||
663 (Data.getFlags() & ELF_STB_Weak)) &&
664 "External symbol requires STB_GLOBAL or STB_WEAK flag");
665 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
666 if (GetBinding(Data) == ELF::STB_LOCAL)
667 LastLocalSymbolIndex++;
670 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) {
671 ELFSymbolData &MSD = UndefinedSymbolData[i];
672 MCSymbolData &Data = *MSD.SymbolData;
673 WriteSymbol(SymtabF, ShndxF, MSD, Layout);
674 if (GetBinding(Data) == ELF::STB_LOCAL)
675 LastLocalSymbolIndex++;
679 const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
680 const MCValue &Target,
681 const MCFragment &F) const {
682 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
683 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
684 const MCSymbol *Renamed = Renames.lookup(&Symbol);
685 const MCSymbolData &SD = Asm.getSymbolData(Symbol);
687 if (ASymbol.isUndefined()) {
693 if (SD.isExternal()) {
699 const MCSectionELF &Section =
700 static_cast<const MCSectionELF&>(ASymbol.getSection());
701 const SectionKind secKind = Section.getKind();
706 if (secKind.isThreadLocal()) {
712 MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
713 const MCSectionELF &Sec2 =
714 static_cast<const MCSectionELF&>(F.getParent()->getSection());
716 if (&Sec2 != &Section &&
717 (Kind == MCSymbolRefExpr::VK_PLT ||
718 Kind == MCSymbolRefExpr::VK_GOTPCREL ||
719 Kind == MCSymbolRefExpr::VK_GOTOFF)) {
725 if (Section.getFlags() & MCSectionELF::SHF_MERGE) {
726 if (Target.getConstant() == 0)
737 void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
738 const MCAsmLayout &Layout,
739 const MCFragment *Fragment,
740 const MCFixup &Fixup,
742 uint64_t &FixedValue) {
745 int64_t Value = Target.getConstant();
746 const MCSymbol *RelocSymbol = NULL;
748 bool IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
749 if (!Target.isAbsolute()) {
750 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
751 const MCSymbol &ASymbol = Symbol.AliasedSymbol();
752 RelocSymbol = SymbolToReloc(Asm, Target, *Fragment);
754 if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
755 const MCSymbol &SymbolB = RefB->getSymbol();
756 MCSymbolData &SDB = Asm.getSymbolData(SymbolB);
759 // Offset of the symbol in the section
760 int64_t a = Layout.getSymbolOffset(&SDB);
762 // Ofeset of the relocation in the section
763 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
768 MCSymbolData &SD = Asm.getSymbolData(ASymbol);
769 MCFragment *F = SD.getFragment();
771 Index = F->getParent()->getOrdinal() + 1;
773 // Offset of the symbol in the section
774 Value += Layout.getSymbolOffset(&SD);
776 if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
777 WeakrefUsedInReloc.insert(RelocSymbol);
779 UsedInReloc.insert(RelocSymbol);
783 // Compensate for the addend on i386.
789 unsigned Type = GetRelocType(Target, Fixup, IsPCRel,
790 (RelocSymbol != 0), Addend);
792 uint64_t RelocOffset = Layout.getFragmentOffset(Fragment) +
795 if (!HasRelocationAddend) Addend = 0;
796 ELFRelocationEntry ERE(RelocOffset, Index, Type, RelocSymbol, Addend);
797 Relocations[Fragment->getParent()].push_back(ERE);
802 ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
804 MCSymbolData &SD = Asm.getSymbolData(*S);
805 return SD.getIndex();
808 static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
809 bool Used, bool Renamed) {
810 if (Data.getFlags() & ELF_Other_Weakref)
819 const MCSymbol &Symbol = Data.getSymbol();
821 if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
824 const MCSymbol &A = Symbol.AliasedSymbol();
825 if (!A.isVariable() && A.isUndefined() && !Data.isCommon())
828 if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
831 if (Symbol.isTemporary())
837 static bool isLocal(const MCSymbolData &Data, bool isSignature,
838 bool isUsedInReloc) {
839 if (Data.isExternal())
842 const MCSymbol &Symbol = Data.getSymbol();
843 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
845 if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
846 if (isSignature && !isUsedInReloc)
855 void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
856 SectionIndexMapTy &SectionIndexMap) {
858 for (MCAssembler::iterator it = Asm.begin(),
859 ie = Asm.end(); it != ie; ++it) {
860 const MCSectionELF &Section =
861 static_cast<const MCSectionELF &>(it->getSection());
862 if (Section.getType() != ELF::SHT_GROUP)
864 SectionIndexMap[&Section] = Index++;
867 for (MCAssembler::iterator it = Asm.begin(),
868 ie = Asm.end(); it != ie; ++it) {
869 const MCSectionELF &Section =
870 static_cast<const MCSectionELF &>(it->getSection());
871 if (Section.getType() == ELF::SHT_GROUP)
873 SectionIndexMap[&Section] = Index++;
877 void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
878 const SectionIndexMapTy &SectionIndexMap,
879 RevGroupMapTy RevGroupMap) {
880 // FIXME: Is this the correct place to do this?
882 llvm::StringRef Name = "_GLOBAL_OFFSET_TABLE_";
883 MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name);
884 MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym);
885 Data.setExternal(true);
886 SetBinding(Data, ELF::STB_GLOBAL);
889 // Build section lookup table.
890 int NumRegularSections = Asm.size();
892 // Index 0 is always the empty string.
893 StringMap<uint64_t> StringIndexMap;
894 StringTable += '\x00';
896 // Add the data for the symbols.
897 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
898 ie = Asm.symbol_end(); it != ie; ++it) {
899 const MCSymbol &Symbol = it->getSymbol();
901 bool Used = UsedInReloc.count(&Symbol);
902 bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
903 bool isSignature = RevGroupMap.count(&Symbol);
905 if (!isInSymtab(Asm, *it,
906 Used || WeakrefUsed || isSignature,
907 Renames.count(&Symbol)))
912 const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
914 // Undefined symbols are global, but this is the first place we
915 // are able to set it.
916 bool Local = isLocal(*it, isSignature, Used);
917 if (!Local && GetBinding(*it) == ELF::STB_LOCAL) {
918 MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
919 SetBinding(*it, ELF::STB_GLOBAL);
920 SetBinding(SD, ELF::STB_GLOBAL);
923 if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
924 SetBinding(*it, ELF::STB_WEAK);
926 if (it->isCommon()) {
928 MSD.SectionIndex = ELF::SHN_COMMON;
929 } else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
930 MSD.SectionIndex = ELF::SHN_ABS;
931 } else if (RefSymbol.isUndefined()) {
932 if (isSignature && !Used)
933 MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
935 MSD.SectionIndex = ELF::SHN_UNDEF;
937 const MCSectionELF &Section =
938 static_cast<const MCSectionELF&>(RefSymbol.getSection());
939 MSD.SectionIndex = SectionIndexMap.lookup(&Section);
940 if (MSD.SectionIndex >= ELF::SHN_LORESERVE)
941 NeedsSymtabShndx = true;
942 assert(MSD.SectionIndex && "Invalid section index!");
945 // The @@@ in symbol version is replaced with @ in undefined symbols and
946 // @@ in defined ones.
947 StringRef Name = Symbol.getName();
950 size_t Pos = Name.find("@@@");
951 if (Pos != StringRef::npos) {
952 Buf += Name.substr(0, Pos);
953 unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
954 Buf += Name.substr(Pos + Skip);
958 uint64_t &Entry = StringIndexMap[Name];
960 Entry = StringTable.size();
962 StringTable += '\x00';
964 MSD.StringIndex = Entry;
965 if (MSD.SectionIndex == ELF::SHN_UNDEF)
966 UndefinedSymbolData.push_back(MSD);
968 LocalSymbolData.push_back(MSD);
970 ExternalSymbolData.push_back(MSD);
973 // Symbols are required to be in lexicographic order.
974 array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end());
975 array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
976 array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
978 // Set the symbol indices. Local symbols must come before all other
979 // symbols with non-local bindings.
981 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
982 LocalSymbolData[i].SymbolData->setIndex(Index++);
984 Index += NumRegularSections;
986 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
987 ExternalSymbolData[i].SymbolData->setIndex(Index++);
988 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
989 UndefinedSymbolData[i].SymbolData->setIndex(Index++);
992 void ELFObjectWriter::WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
993 const MCSectionData &SD) {
994 if (!Relocations[&SD].empty()) {
995 MCContext &Ctx = Asm.getContext();
996 const MCSectionELF *RelaSection;
997 const MCSectionELF &Section =
998 static_cast<const MCSectionELF&>(SD.getSection());
1000 const StringRef SectionName = Section.getSectionName();
1001 std::string RelaSectionName = HasRelocationAddend ? ".rela" : ".rel";
1002 RelaSectionName += SectionName;
1005 if (HasRelocationAddend)
1006 EntrySize = Is64Bit ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
1008 EntrySize = Is64Bit ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
1010 RelaSection = Ctx.getELFSection(RelaSectionName, HasRelocationAddend ?
1011 ELF::SHT_RELA : ELF::SHT_REL, 0,
1012 SectionKind::getReadOnly(),
1015 MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
1016 RelaSD.setAlignment(Is64Bit ? 8 : 4);
1018 MCDataFragment *F = new MCDataFragment(&RelaSD);
1020 WriteRelocationsFragment(Asm, F, &SD);
1024 void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type,
1025 uint64_t Flags, uint64_t Address,
1026 uint64_t Offset, uint64_t Size,
1027 uint32_t Link, uint32_t Info,
1029 uint64_t EntrySize) {
1030 Write32(Name); // sh_name: index into string table
1031 Write32(Type); // sh_type
1032 WriteWord(Flags); // sh_flags
1033 WriteWord(Address); // sh_addr
1034 WriteWord(Offset); // sh_offset
1035 WriteWord(Size); // sh_size
1036 Write32(Link); // sh_link
1037 Write32(Info); // sh_info
1038 WriteWord(Alignment); // sh_addralign
1039 WriteWord(EntrySize); // sh_entsize
1042 void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
1044 const MCSectionData *SD) {
1045 std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
1046 // sort by the r_offset just like gnu as does
1047 array_pod_sort(Relocs.begin(), Relocs.end());
1049 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
1050 ELFRelocationEntry entry = Relocs[e - i - 1];
1054 else if (entry.Index < 0)
1055 entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol);
1057 entry.Index += LocalSymbolData.size();
1059 String64(*F, entry.r_offset);
1061 struct ELF::Elf64_Rela ERE64;
1062 ERE64.setSymbolAndType(entry.Index, entry.Type);
1063 String64(*F, ERE64.r_info);
1065 if (HasRelocationAddend)
1066 String64(*F, entry.r_addend);
1068 String32(*F, entry.r_offset);
1070 struct ELF::Elf32_Rela ERE32;
1071 ERE32.setSymbolAndType(entry.Index, entry.Type);
1072 String32(*F, ERE32.r_info);
1074 if (HasRelocationAddend)
1075 String32(*F, entry.r_addend);
1080 void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
1081 MCAsmLayout &Layout,
1082 const SectionIndexMapTy &SectionIndexMap) {
1083 MCContext &Ctx = Asm.getContext();
1086 unsigned EntrySize = Is64Bit ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
1088 // We construct .shstrtab, .symtab and .strtab in this order to match gnu as.
1089 const MCSectionELF *ShstrtabSection =
1090 Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0,
1091 SectionKind::getReadOnly());
1092 MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
1093 ShstrtabSD.setAlignment(1);
1094 ShstrtabIndex = Asm.size();
1096 const MCSectionELF *SymtabSection =
1097 Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
1098 SectionKind::getReadOnly(),
1100 MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
1101 SymtabSD.setAlignment(Is64Bit ? 8 : 4);
1102 SymbolTableIndex = Asm.size();
1104 MCSectionData *SymtabShndxSD = NULL;
1106 if (NeedsSymtabShndx) {
1107 const MCSectionELF *SymtabShndxSection =
1108 Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0,
1109 SectionKind::getReadOnly(), 4, "");
1110 SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection);
1111 SymtabShndxSD->setAlignment(4);
1114 const MCSection *StrtabSection;
1115 StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
1116 SectionKind::getReadOnly());
1117 MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
1118 StrtabSD.setAlignment(1);
1119 StringTableIndex = Asm.size();
1121 WriteRelocations(Asm, Layout);
1124 F = new MCDataFragment(&SymtabSD);
1125 MCDataFragment *ShndxF = NULL;
1126 if (NeedsSymtabShndx) {
1127 ShndxF = new MCDataFragment(SymtabShndxSD);
1129 WriteSymbolTable(F, ShndxF, Asm, Layout, SectionIndexMap);
1131 F = new MCDataFragment(&StrtabSD);
1132 F->getContents().append(StringTable.begin(), StringTable.end());
1134 F = new MCDataFragment(&ShstrtabSD);
1136 // Section header string table.
1138 // The first entry of a string table holds a null character so skip
1141 F->getContents() += '\x00';
1143 StringMap<uint64_t> SecStringMap;
1144 for (MCAssembler::const_iterator it = Asm.begin(),
1145 ie = Asm.end(); it != ie; ++it) {
1146 const MCSectionELF &Section =
1147 static_cast<const MCSectionELF&>(it->getSection());
1148 // FIXME: We could merge suffixes like in .text and .rela.text.
1150 StringRef Name = Section.getSectionName();
1151 if (SecStringMap.count(Name)) {
1152 SectionStringTableIndex[&Section] = SecStringMap[Name];
1155 // Remember the index into the string table so we can write it
1156 // into the sh_name field of the section header table.
1157 SectionStringTableIndex[&Section] = Index;
1158 SecStringMap[Name] = Index;
1160 Index += Name.size() + 1;
1161 F->getContents() += Name;
1162 F->getContents() += '\x00';
1166 bool ELFObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
1167 const MCValue Target,
1169 const MCFragment *DF) const {
1170 // If this is a PCrel relocation, find the section this fixup value is
1172 const MCSection *BaseSection = 0;
1174 BaseSection = &DF->getParent()->getSection();
1175 assert(BaseSection);
1178 const MCSection *SectionA = 0;
1179 const MCSymbol *SymbolA = 0;
1180 if (const MCSymbolRefExpr *A = Target.getSymA()) {
1181 SymbolA = &A->getSymbol();
1182 SectionA = &SymbolA->AliasedSymbol().getSection();
1185 const MCSection *SectionB = 0;
1186 const MCSymbol *SymbolB = 0;
1187 if (const MCSymbolRefExpr *B = Target.getSymB()) {
1188 SymbolB = &B->getSymbol();
1189 SectionB = &SymbolB->AliasedSymbol().getSection();
1193 return SectionA == SectionB;
1198 // Absolute address but PCrel instruction, so we need a relocation.
1202 // FIXME: This is in here just to match gnu as output. If the two ends
1203 // are in the same section, there is nothing that the linker can do to
1205 const MCSymbolData &DataA = Asm.getSymbolData(*SymbolA);
1206 if (DataA.isExternal())
1209 return BaseSection == SectionA;
1212 void ELFObjectWriter::CreateGroupSections(MCAssembler &Asm,
1213 MCAsmLayout &Layout,
1214 GroupMapTy &GroupMap,
1215 RevGroupMapTy &RevGroupMap) {
1217 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1219 const MCSectionELF &Section =
1220 static_cast<const MCSectionELF&>(it->getSection());
1221 if (!(Section.getFlags() & MCSectionELF::SHF_GROUP))
1224 const MCSymbol *SignatureSymbol = Section.getGroup();
1225 Asm.getOrCreateSymbolData(*SignatureSymbol);
1226 const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
1228 Group = Asm.getContext().CreateELFGroupSection();
1229 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1230 Data.setAlignment(4);
1231 MCDataFragment *F = new MCDataFragment(&Data);
1232 String32(*F, ELF::GRP_COMDAT);
1234 GroupMap[Group] = SignatureSymbol;
1237 // Add sections to the groups
1239 unsigned NumGroups = RevGroupMap.size();
1240 for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1241 it != ie; ++it, ++Index) {
1242 const MCSectionELF &Section =
1243 static_cast<const MCSectionELF&>(it->getSection());
1244 if (!(Section.getFlags() & MCSectionELF::SHF_GROUP))
1246 const MCSectionELF *Group = RevGroupMap[Section.getGroup()];
1247 MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1248 // FIXME: we could use the previous fragment
1249 MCDataFragment *F = new MCDataFragment(&Data);
1250 String32(*F, NumGroups + Index);
1254 void ELFObjectWriter::WriteSection(MCAssembler &Asm,
1255 const SectionIndexMapTy &SectionIndexMap,
1256 uint32_t GroupSymbolIndex,
1257 uint64_t Offset, uint64_t Size,
1259 const MCSectionELF &Section) {
1260 uint64_t sh_link = 0;
1261 uint64_t sh_info = 0;
1263 switch(Section.getType()) {
1264 case ELF::SHT_DYNAMIC:
1265 sh_link = SectionStringTableIndex[&Section];
1270 case ELF::SHT_RELA: {
1271 const MCSectionELF *SymtabSection;
1272 const MCSectionELF *InfoSection;
1273 SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB,
1275 SectionKind::getReadOnly());
1276 sh_link = SectionIndexMap.lookup(SymtabSection);
1277 assert(sh_link && ".symtab not found");
1279 // Remove ".rel" and ".rela" prefixes.
1280 unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
1281 StringRef SectionName = Section.getSectionName().substr(SecNameLen);
1283 InfoSection = Asm.getContext().getELFSection(SectionName,
1284 ELF::SHT_PROGBITS, 0,
1285 SectionKind::getReadOnly());
1286 sh_info = SectionIndexMap.lookup(InfoSection);
1290 case ELF::SHT_SYMTAB:
1291 case ELF::SHT_DYNSYM:
1292 sh_link = StringTableIndex;
1293 sh_info = LastLocalSymbolIndex;
1296 case ELF::SHT_SYMTAB_SHNDX:
1297 sh_link = SymbolTableIndex;
1300 case ELF::SHT_PROGBITS:
1301 case ELF::SHT_STRTAB:
1302 case ELF::SHT_NOBITS:
1304 case ELF::SHT_ARM_ATTRIBUTES:
1308 case ELF::SHT_GROUP: {
1309 sh_link = SymbolTableIndex;
1310 sh_info = GroupSymbolIndex;
1315 assert(0 && "FIXME: sh_type value not supported!");
1319 WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(),
1320 Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
1321 Alignment, Section.getEntrySize());
1324 static bool IsELFMetaDataSection(const MCSectionData &SD) {
1325 return SD.getOrdinal() == ~UINT32_C(0) &&
1326 !SD.getSection().isVirtualSection();
1329 static uint64_t DataSectionSize(const MCSectionData &SD) {
1331 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1333 const MCFragment &F = *i;
1334 assert(F.getKind() == MCFragment::FT_Data);
1335 Ret += cast<MCDataFragment>(F).getContents().size();
1340 static uint64_t GetSectionFileSize(const MCAsmLayout &Layout,
1341 const MCSectionData &SD) {
1342 if (IsELFMetaDataSection(SD))
1343 return DataSectionSize(SD);
1344 return Layout.getSectionFileSize(&SD);
1347 static uint64_t GetSectionAddressSize(const MCAsmLayout &Layout,
1348 const MCSectionData &SD) {
1349 if (IsELFMetaDataSection(SD))
1350 return DataSectionSize(SD);
1351 return Layout.getSectionAddressSize(&SD);
1354 static void WriteDataSectionData(ELFObjectWriter *W, const MCSectionData &SD) {
1355 for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1357 const MCFragment &F = *i;
1358 assert(F.getKind() == MCFragment::FT_Data);
1359 W->WriteBytes(cast<MCDataFragment>(F).getContents().str());
1363 void ELFObjectWriter::WriteObject(MCAssembler &Asm,
1364 const MCAsmLayout &Layout) {
1365 GroupMapTy GroupMap;
1366 RevGroupMapTy RevGroupMap;
1367 CreateGroupSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
1370 SectionIndexMapTy SectionIndexMap;
1372 ComputeIndexMap(Asm, SectionIndexMap);
1374 // Compute symbol table information.
1375 ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap);
1377 CreateMetadataSections(const_cast<MCAssembler&>(Asm),
1378 const_cast<MCAsmLayout&>(Layout),
1381 // Update to include the metadata sections.
1382 ComputeIndexMap(Asm, SectionIndexMap);
1384 // Add 1 for the null section.
1385 unsigned NumSections = Asm.size() + 1;
1386 uint64_t NaturalAlignment = Is64Bit ? 8 : 4;
1387 uint64_t HeaderSize = Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr);
1388 uint64_t FileOff = HeaderSize;
1390 std::vector<const MCSectionELF*> Sections;
1391 Sections.resize(NumSections);
1393 for (SectionIndexMapTy::const_iterator i=
1394 SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) {
1395 const std::pair<const MCSectionELF*, uint32_t> &p = *i;
1396 Sections[p.second] = p.first;
1399 for (unsigned i = 1; i < NumSections; ++i) {
1400 const MCSectionELF &Section = *Sections[i];
1401 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1403 FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
1405 // Get the size of the section in the output file (including padding).
1406 FileOff += GetSectionFileSize(Layout, SD);
1409 FileOff = RoundUpToAlignment(FileOff, NaturalAlignment);
1411 // Write out the ELF header ...
1412 WriteHeader(FileOff - HeaderSize, NumSections);
1414 FileOff = HeaderSize;
1416 // ... then all of the sections ...
1417 DenseMap<const MCSection*, uint64_t> SectionOffsetMap;
1419 for (unsigned i = 1; i < NumSections; ++i) {
1420 const MCSectionELF &Section = *Sections[i];
1421 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1423 uint64_t Padding = OffsetToAlignment(FileOff, SD.getAlignment());
1424 WriteZeros(Padding);
1427 // Remember the offset into the file for this section.
1428 SectionOffsetMap[&Section] = FileOff;
1430 FileOff += GetSectionFileSize(Layout, SD);
1432 if (IsELFMetaDataSection(SD))
1433 WriteDataSectionData(this, SD);
1435 Asm.WriteSectionData(&SD, Layout);
1438 uint64_t Padding = OffsetToAlignment(FileOff, NaturalAlignment);
1439 WriteZeros(Padding);
1442 // ... and then the section header table.
1443 // Should we align the section header table?
1445 // Null section first.
1446 uint64_t FirstSectionSize =
1447 NumSections >= ELF::SHN_LORESERVE ? NumSections : 0;
1448 uint32_t FirstSectionLink =
1449 ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0;
1450 WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0);
1452 for (unsigned i = 1; i < NumSections; ++i) {
1453 const MCSectionELF &Section = *Sections[i];
1454 const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1455 uint32_t GroupSymbolIndex;
1456 if (Section.getType() != ELF::SHT_GROUP)
1457 GroupSymbolIndex = 0;
1459 GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm, GroupMap[&Section]);
1461 uint64_t Size = GetSectionAddressSize(Layout, SD);
1463 WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
1464 SectionOffsetMap[&Section], Size,
1465 SD.getAlignment(), Section);
1469 MCObjectWriter *llvm::createELFObjectWriter(raw_ostream &OS,
1471 Triple::OSType OSType,
1473 bool IsLittleEndian,
1474 bool HasRelocationAddend) {
1477 case ELF::EM_X86_64:
1478 return new X86ELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
1479 HasRelocationAddend, OSType); break;
1481 return new ARMELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
1482 HasRelocationAddend, OSType); break;
1483 case ELF::EM_MBLAZE:
1484 return new MBlazeELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
1485 HasRelocationAddend, OSType); break;
1486 default: llvm_unreachable("Unsupported architecture"); break;
1491 /// START OF SUBCLASSES for ELFObjectWriter
1492 //===- ARMELFObjectWriter -------------------------------------------===//
1494 ARMELFObjectWriter::ARMELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
1495 bool _IsLittleEndian,
1496 uint16_t _EMachine, bool _HasRelocationAddend,
1497 Triple::OSType _OSType)
1498 : ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
1499 _HasRelocationAddend, _OSType)
1502 ARMELFObjectWriter::~ARMELFObjectWriter()
1505 unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target,
1506 const MCFixup &Fixup,
1508 bool IsRelocWithSymbol,
1510 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
1511 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
1515 switch ((unsigned)Fixup.getKind()) {
1516 default: assert(0 && "Unimplemented");
1519 default: llvm_unreachable("Unsupported Modifier");
1520 case MCSymbolRefExpr::VK_None:
1521 Type = ELF::R_ARM_BASE_PREL; break;
1522 case MCSymbolRefExpr::VK_ARM_TLSGD:
1523 assert(0 && "unimplemented"); break;
1524 case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
1525 Type = ELF::R_ARM_TLS_IE32;
1527 case ARM::fixup_arm_branch:
1529 case MCSymbolRefExpr::VK_ARM_PLT:
1530 Type = ELF::R_ARM_PLT32; break;
1532 Type = ELF::R_ARM_CALL; break;
1536 switch ((unsigned)Fixup.getKind()) {
1537 default: llvm_unreachable("invalid fixup kind!");
1540 default: llvm_unreachable("Unsupported Modifier"); break;
1541 case MCSymbolRefExpr::VK_ARM_GOT:
1542 Type = ELF::R_ARM_GOT_BREL; break;
1543 case MCSymbolRefExpr::VK_ARM_TLSGD:
1544 Type = ELF::R_ARM_TLS_GD32; break;
1545 case MCSymbolRefExpr::VK_ARM_TPOFF:
1546 Type = ELF::R_ARM_TLS_LE32; break;
1547 case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
1548 Type = ELF::R_ARM_TLS_IE32; break;
1549 case MCSymbolRefExpr::VK_None:
1550 Type = ELF::R_ARM_ABS32; break;
1551 case MCSymbolRefExpr::VK_ARM_GOTOFF:
1552 Type = ELF::R_ARM_GOTOFF32; break;
1554 case ARM::fixup_arm_ldst_pcrel_12:
1555 case ARM::fixup_arm_pcrel_10:
1556 case ARM::fixup_arm_adr_pcrel_12:
1557 case ARM::fixup_arm_thumb_bl:
1558 case ARM::fixup_arm_thumb_cb:
1559 case ARM::fixup_arm_thumb_cp:
1560 case ARM::fixup_arm_thumb_br:
1561 assert(0 && "Unimplemented"); break;
1562 case ARM::fixup_arm_branch:
1563 // FIXME: Differentiate between R_ARM_CALL and
1564 // R_ARM_JUMP24 (latter used for conditional jumps)
1565 Type = ELF::R_ARM_CALL; break;
1566 case ARM::fixup_arm_movt_hi16:
1567 Type = ELF::R_ARM_MOVT_ABS; break;
1568 case ARM::fixup_arm_movw_lo16:
1569 Type = ELF::R_ARM_MOVW_ABS_NC; break;
1573 if (RelocNeedsGOT(Modifier))
1579 //===- MBlazeELFObjectWriter -------------------------------------------===//
1581 MBlazeELFObjectWriter::MBlazeELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
1582 bool _IsLittleEndian,
1584 bool _HasRelocationAddend,
1585 Triple::OSType _OSType)
1586 : ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
1587 _HasRelocationAddend, _OSType) {
1590 MBlazeELFObjectWriter::~MBlazeELFObjectWriter() {
1593 unsigned MBlazeELFObjectWriter::GetRelocType(const MCValue &Target,
1594 const MCFixup &Fixup,
1596 bool IsRelocWithSymbol,
1598 // determine the type of the relocation
1601 switch ((unsigned)Fixup.getKind()) {
1603 llvm_unreachable("Unimplemented");
1605 Type = ELF::R_MICROBLAZE_64_PCREL;
1608 Type = ELF::R_MICROBLAZE_32_PCREL;
1612 switch ((unsigned)Fixup.getKind()) {
1613 default: llvm_unreachable("invalid fixup kind!");
1615 Type = ((IsRelocWithSymbol || Addend !=0)
1616 ? ELF::R_MICROBLAZE_32
1617 : ELF::R_MICROBLAZE_64);
1620 Type = ELF::R_MICROBLAZE_32;
1627 //===- X86ELFObjectWriter -------------------------------------------===//
1630 X86ELFObjectWriter::X86ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
1631 bool _IsLittleEndian,
1632 uint16_t _EMachine, bool _HasRelocationAddend,
1633 Triple::OSType _OSType)
1634 : ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
1635 _HasRelocationAddend, _OSType)
1638 X86ELFObjectWriter::~X86ELFObjectWriter()
1641 unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
1642 const MCFixup &Fixup,
1644 bool IsRelocWithSymbol,
1646 // determine the type of the relocation
1648 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
1649 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
1655 llvm_unreachable("Unimplemented");
1656 case MCSymbolRefExpr::VK_None:
1657 Type = ELF::R_X86_64_PC32;
1659 case MCSymbolRefExpr::VK_PLT:
1660 Type = ELF::R_X86_64_PLT32;
1662 case MCSymbolRefExpr::VK_GOTPCREL:
1663 Type = ELF::R_X86_64_GOTPCREL;
1665 case MCSymbolRefExpr::VK_GOTTPOFF:
1666 Type = ELF::R_X86_64_GOTTPOFF;
1668 case MCSymbolRefExpr::VK_TLSGD:
1669 Type = ELF::R_X86_64_TLSGD;
1671 case MCSymbolRefExpr::VK_TLSLD:
1672 Type = ELF::R_X86_64_TLSLD;
1676 switch ((unsigned)Fixup.getKind()) {
1677 default: llvm_unreachable("invalid fixup kind!");
1678 case FK_Data_8: Type = ELF::R_X86_64_64; break;
1679 case X86::reloc_signed_4byte:
1681 assert(isInt<32>(Target.getConstant()));
1684 llvm_unreachable("Unimplemented");
1685 case MCSymbolRefExpr::VK_None:
1686 Type = ELF::R_X86_64_32S;
1688 case MCSymbolRefExpr::VK_GOT:
1689 Type = ELF::R_X86_64_GOT32;
1691 case MCSymbolRefExpr::VK_GOTPCREL:
1692 Type = ELF::R_X86_64_GOTPCREL;
1694 case MCSymbolRefExpr::VK_TPOFF:
1695 Type = ELF::R_X86_64_TPOFF32;
1697 case MCSymbolRefExpr::VK_DTPOFF:
1698 Type = ELF::R_X86_64_DTPOFF32;
1703 Type = ELF::R_X86_64_32;
1705 case FK_Data_2: Type = ELF::R_X86_64_16; break;
1707 case FK_Data_1: Type = ELF::R_X86_64_8; break;
1714 llvm_unreachable("Unimplemented");
1715 case MCSymbolRefExpr::VK_None:
1716 Type = ELF::R_386_PC32;
1718 case MCSymbolRefExpr::VK_PLT:
1719 Type = ELF::R_386_PLT32;
1723 switch ((unsigned)Fixup.getKind()) {
1724 default: llvm_unreachable("invalid fixup kind!");
1726 case X86::reloc_global_offset_table:
1727 Type = ELF::R_386_GOTPC;
1730 // FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode
1732 case X86::reloc_signed_4byte:
1737 llvm_unreachable("Unimplemented");
1738 case MCSymbolRefExpr::VK_None:
1739 Type = ELF::R_386_32;
1741 case MCSymbolRefExpr::VK_GOT:
1742 Type = ELF::R_386_GOT32;
1744 case MCSymbolRefExpr::VK_GOTOFF:
1745 Type = ELF::R_386_GOTOFF;
1747 case MCSymbolRefExpr::VK_TLSGD:
1748 Type = ELF::R_386_TLS_GD;
1750 case MCSymbolRefExpr::VK_TPOFF:
1751 Type = ELF::R_386_TLS_LE_32;
1753 case MCSymbolRefExpr::VK_INDNTPOFF:
1754 Type = ELF::R_386_TLS_IE;
1756 case MCSymbolRefExpr::VK_NTPOFF:
1757 Type = ELF::R_386_TLS_LE;
1759 case MCSymbolRefExpr::VK_GOTNTPOFF:
1760 Type = ELF::R_386_TLS_GOTIE;
1762 case MCSymbolRefExpr::VK_TLSLDM:
1763 Type = ELF::R_386_TLS_LDM;
1765 case MCSymbolRefExpr::VK_DTPOFF:
1766 Type = ELF::R_386_TLS_LDO_32;
1770 case FK_Data_2: Type = ELF::R_386_16; break;
1772 case FK_Data_1: Type = ELF::R_386_8; break;
1777 if (RelocNeedsGOT(Modifier))