ELFObjectWriter.cpp revision 285b3e5b61af15f11e59a7700375aefa2a326bd8 
1//===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements ELF object file writer information.
11//
12//===----------------------------------------------------------------------===//
13
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/MCELFObjectWriter.h"
24#include "llvm/MC/MCObjectWriter.h"
25#include "llvm/MC/MCSectionELF.h"
26#include "llvm/MC/MCSymbol.h"
27#include "llvm/MC/MCValue.h"
28#include "llvm/Support/Debug.h"
29#include "llvm/Support/ErrorHandling.h"
30#include "llvm/Support/ELF.h"
31#include "llvm/Target/TargetAsmBackend.h"
32
33#include "../Target/X86/X86FixupKinds.h"
34#include "../Target/ARM/ARMFixupKinds.h"
35
36#include <vector>
37using namespace llvm;
38
39static unsigned GetType(const MCSymbolData &SD) {
40  uint32_t Type = (SD.getFlags() & (0xf << ELF_STT_Shift)) >> ELF_STT_Shift;
41  assert(Type == ELF::STT_NOTYPE || Type == ELF::STT_OBJECT ||
42         Type == ELF::STT_FUNC || Type == ELF::STT_SECTION ||
43         Type == ELF::STT_FILE || Type == ELF::STT_COMMON ||
44         Type == ELF::STT_TLS);
45  return Type;
46}
47
48static unsigned GetBinding(const MCSymbolData &SD) {
49  uint32_t Binding = (SD.getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift;
50  assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
51         Binding == ELF::STB_WEAK);
52  return Binding;
53}
54
55static void SetBinding(MCSymbolData &SD, unsigned Binding) {
56  assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
57         Binding == ELF::STB_WEAK);
58  uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STB_Shift);
59  SD.setFlags(OtherFlags | (Binding << ELF_STB_Shift));
60}
61
62static unsigned GetVisibility(MCSymbolData &SD) {
63  unsigned Visibility =
64    (SD.getFlags() & (0xf << ELF_STV_Shift)) >> ELF_STV_Shift;
65  assert(Visibility == ELF::STV_DEFAULT || Visibility == ELF::STV_INTERNAL ||
66         Visibility == ELF::STV_HIDDEN || Visibility == ELF::STV_PROTECTED);
67  return Visibility;
68}
69
70
71static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) {
72  switch (Variant) {
73  default:
74    return false;
75  case MCSymbolRefExpr::VK_GOT:
76  case MCSymbolRefExpr::VK_PLT:
77  case MCSymbolRefExpr::VK_GOTPCREL:
78  case MCSymbolRefExpr::VK_TPOFF:
79  case MCSymbolRefExpr::VK_TLSGD:
80  case MCSymbolRefExpr::VK_GOTTPOFF:
81  case MCSymbolRefExpr::VK_INDNTPOFF:
82  case MCSymbolRefExpr::VK_NTPOFF:
83  case MCSymbolRefExpr::VK_GOTNTPOFF:
84  case MCSymbolRefExpr::VK_TLSLDM:
85  case MCSymbolRefExpr::VK_DTPOFF:
86  case MCSymbolRefExpr::VK_TLSLD:
87    return true;
88  }
89}
90
91static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) {
92  const MCFixupKindInfo &FKI =
93    Asm.getBackend().getFixupKindInfo((MCFixupKind) Kind);
94
95  return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel;
96}
97
98namespace {
99  class ELFObjectWriter : public MCObjectWriter {
100  protected:
101    /*static bool isFixupKindX86RIPRel(unsigned Kind) {
102      return Kind == X86::reloc_riprel_4byte ||
103        Kind == X86::reloc_riprel_4byte_movq_load;
104    }*/
105
106
107    /// ELFSymbolData - Helper struct for containing some precomputed information
108    /// on symbols.
109    struct ELFSymbolData {
110      MCSymbolData *SymbolData;
111      uint64_t StringIndex;
112      uint32_t SectionIndex;
113
114      // Support lexicographic sorting.
115      bool operator<(const ELFSymbolData &RHS) const {
116        if (GetType(*SymbolData) == ELF::STT_FILE)
117          return true;
118        if (GetType(*RHS.SymbolData) == ELF::STT_FILE)
119          return false;
120        return SymbolData->getSymbol().getName() <
121               RHS.SymbolData->getSymbol().getName();
122      }
123    };
124
125    /// @name Relocation Data
126    /// @{
127
128    struct ELFRelocationEntry {
129      // Make these big enough for both 32-bit and 64-bit
130      uint64_t r_offset;
131      int Index;
132      unsigned Type;
133      const MCSymbol *Symbol;
134      uint64_t r_addend;
135
136      ELFRelocationEntry()
137        : r_offset(0), Index(0), Type(0), Symbol(0), r_addend(0) {}
138
139      ELFRelocationEntry(uint64_t RelocOffset, int Idx,
140                         unsigned RelType, const MCSymbol *Sym,
141                         uint64_t Addend)
142        : r_offset(RelocOffset), Index(Idx), Type(RelType),
143          Symbol(Sym), r_addend(Addend) {}
144
145      // Support lexicographic sorting.
146      bool operator<(const ELFRelocationEntry &RE) const {
147        return RE.r_offset < r_offset;
148      }
149    };
150
151    SmallPtrSet<const MCSymbol *, 16> UsedInReloc;
152    SmallPtrSet<const MCSymbol *, 16> WeakrefUsedInReloc;
153    DenseMap<const MCSymbol *, const MCSymbol *> Renames;
154
155    llvm::DenseMap<const MCSectionData*,
156                   std::vector<ELFRelocationEntry> > Relocations;
157    DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
158
159    /// @}
160    /// @name Symbol Table Data
161    /// @{
162
163    SmallString<256> StringTable;
164    std::vector<ELFSymbolData> LocalSymbolData;
165    std::vector<ELFSymbolData> ExternalSymbolData;
166    std::vector<ELFSymbolData> UndefinedSymbolData;
167
168    /// @}
169
170    bool NeedsGOT;
171
172    bool NeedsSymtabShndx;
173
174    unsigned Is64Bit : 1;
175
176    bool HasRelocationAddend;
177
178    Triple::OSType OSType;
179
180    uint16_t EMachine;
181
182    // This holds the symbol table index of the last local symbol.
183    unsigned LastLocalSymbolIndex;
184    // This holds the .strtab section index.
185    unsigned StringTableIndex;
186    // This holds the .symtab section index.
187    unsigned SymbolTableIndex;
188
189    unsigned ShstrtabIndex;
190
191
192    const MCSymbol *SymbolToReloc(const MCAssembler &Asm,
193                                  const MCValue &Target,
194                                  const MCFragment &F) const;
195
196  public:
197    ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
198                    uint16_t _EMachine, bool _HasRelAddend,
199                    Triple::OSType _OSType)
200      : MCObjectWriter(_OS, IsLittleEndian),
201        NeedsGOT(false), NeedsSymtabShndx(false),
202        Is64Bit(_Is64Bit), HasRelocationAddend(_HasRelAddend),
203        OSType(_OSType), EMachine(_EMachine) {
204    }
205
206    virtual ~ELFObjectWriter();
207
208    void WriteWord(uint64_t W) {
209      if (Is64Bit)
210        Write64(W);
211      else
212        Write32(W);
213    }
214
215    void StringLE16(char *buf, uint16_t Value) {
216      buf[0] = char(Value >> 0);
217      buf[1] = char(Value >> 8);
218    }
219
220    void StringLE32(char *buf, uint32_t Value) {
221      StringLE16(buf, uint16_t(Value >> 0));
222      StringLE16(buf + 2, uint16_t(Value >> 16));
223    }
224
225    void StringLE64(char *buf, uint64_t Value) {
226      StringLE32(buf, uint32_t(Value >> 0));
227      StringLE32(buf + 4, uint32_t(Value >> 32));
228    }
229
230    void StringBE16(char *buf ,uint16_t Value) {
231      buf[0] = char(Value >> 8);
232      buf[1] = char(Value >> 0);
233    }
234
235    void StringBE32(char *buf, uint32_t Value) {
236      StringBE16(buf, uint16_t(Value >> 16));
237      StringBE16(buf + 2, uint16_t(Value >> 0));
238    }
239
240    void StringBE64(char *buf, uint64_t Value) {
241      StringBE32(buf, uint32_t(Value >> 32));
242      StringBE32(buf + 4, uint32_t(Value >> 0));
243    }
244
245    void String8(MCDataFragment &F, uint8_t Value) {
246      char buf[1];
247      buf[0] = Value;
248      F.getContents() += StringRef(buf, 1);
249    }
250
251    void String16(MCDataFragment &F, uint16_t Value) {
252      char buf[2];
253      if (isLittleEndian())
254        StringLE16(buf, Value);
255      else
256        StringBE16(buf, Value);
257      F.getContents() += StringRef(buf, 2);
258    }
259
260    void String32(MCDataFragment &F, uint32_t Value) {
261      char buf[4];
262      if (isLittleEndian())
263        StringLE32(buf, Value);
264      else
265        StringBE32(buf, Value);
266      F.getContents() += StringRef(buf, 4);
267    }
268
269    void String64(MCDataFragment &F, uint64_t Value) {
270      char buf[8];
271      if (isLittleEndian())
272        StringLE64(buf, Value);
273      else
274        StringBE64(buf, Value);
275      F.getContents() += StringRef(buf, 8);
276    }
277
278    virtual void WriteHeader(uint64_t SectionDataSize, unsigned NumberOfSections);
279
280    virtual void WriteSymbolEntry(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
281                          uint64_t name, uint8_t info,
282                          uint64_t value, uint64_t size,
283                          uint8_t other, uint32_t shndx,
284                          bool Reserved);
285
286    virtual void WriteSymbol(MCDataFragment *SymtabF,  MCDataFragment *ShndxF,
287                     ELFSymbolData &MSD,
288                     const MCAsmLayout &Layout);
289
290    typedef DenseMap<const MCSectionELF*, uint32_t> SectionIndexMapTy;
291    virtual void WriteSymbolTable(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
292                          const MCAssembler &Asm,
293                          const MCAsmLayout &Layout,
294                          const SectionIndexMapTy &SectionIndexMap);
295
296    virtual void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
297                                  const MCFragment *Fragment, const MCFixup &Fixup,
298                                  MCValue Target, uint64_t &FixedValue);
299
300    virtual uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
301                                         const MCSymbol *S);
302
303    // Map from a group section to the signature symbol
304    typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
305    // Map from a signature symbol to the group section
306    typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
307
308    /// ComputeSymbolTable - Compute the symbol table data
309    ///
310    /// \param StringTable [out] - The string table data.
311    /// \param StringIndexMap [out] - Map from symbol names to offsets in the
312    /// string table.
313    virtual void ComputeSymbolTable(MCAssembler &Asm,
314                            const SectionIndexMapTy &SectionIndexMap,
315                            RevGroupMapTy RevGroupMap);
316
317    virtual void ComputeIndexMap(MCAssembler &Asm,
318                         SectionIndexMapTy &SectionIndexMap);
319
320    virtual void WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
321                         const MCSectionData &SD);
322
323    virtual void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout) {
324      for (MCAssembler::const_iterator it = Asm.begin(),
325             ie = Asm.end(); it != ie; ++it) {
326        WriteRelocation(Asm, Layout, *it);
327      }
328    }
329
330    virtual void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
331                                const SectionIndexMapTy &SectionIndexMap);
332
333    virtual void CreateGroupSections(MCAssembler &Asm, MCAsmLayout &Layout,
334                             GroupMapTy &GroupMap, RevGroupMapTy &RevGroupMap);
335
336    virtual void ExecutePostLayoutBinding(MCAssembler &Asm,
337                                          const MCAsmLayout &Layout);
338
339    virtual void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
340                          uint64_t Address, uint64_t Offset,
341                          uint64_t Size, uint32_t Link, uint32_t Info,
342                          uint64_t Alignment, uint64_t EntrySize);
343
344    virtual void WriteRelocationsFragment(const MCAssembler &Asm,
345                                          MCDataFragment *F,
346                                          const MCSectionData *SD);
347
348    virtual bool
349    IsSymbolRefDifferenceFullyResolved(const MCAssembler &Asm,
350                                       const MCSymbolRefExpr *A,
351                                       const MCSymbolRefExpr *B) const {
352      // FIXME: Implement this!
353      return false;
354    }
355
356    virtual bool IsFixupFullyResolved(const MCAssembler &Asm,
357                              const MCValue Target,
358                              bool IsPCRel,
359                              const MCFragment *DF) const;
360
361    virtual void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
362    virtual void WriteSection(MCAssembler &Asm,
363                      const SectionIndexMapTy &SectionIndexMap,
364                      uint32_t GroupSymbolIndex,
365                      uint64_t Offset, uint64_t Size, uint64_t Alignment,
366                      const MCSectionELF &Section);
367
368  protected:
369    virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
370                                  bool IsPCRel, bool IsRelocWithSymbol,
371                                  int64_t Addend) = 0;
372  };
373
374  //===- X86ELFObjectWriter -------------------------------------------===//
375
376  class X86ELFObjectWriter : public ELFObjectWriter {
377  public:
378    X86ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
379                       uint16_t _EMachine, bool _HasRelAddend,
380                       Triple::OSType _OSType);
381
382    virtual ~X86ELFObjectWriter();
383  protected:
384    virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
385                                  bool IsPCRel, bool IsRelocWithSymbol,
386                                  int64_t Addend);
387  };
388
389
390  //===- ARMELFObjectWriter -------------------------------------------===//
391
392  class ARMELFObjectWriter : public ELFObjectWriter {
393  public:
394    ARMELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
395                       uint16_t _EMachine, bool _HasRelAddend,
396                       Triple::OSType _OSType);
397
398    virtual ~ARMELFObjectWriter();
399  protected:
400    virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
401                                  bool IsPCRel, bool IsRelocWithSymbol,
402                                  int64_t Addend);
403  };
404
405  //===- MBlazeELFObjectWriter -------------------------------------------===//
406
407  class MBlazeELFObjectWriter : public ELFObjectWriter {
408  public:
409    MBlazeELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
410                          uint16_t _EMachine, bool _HasRelAddend,
411                          Triple::OSType _OSType);
412
413    virtual ~MBlazeELFObjectWriter();
414  protected:
415    virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
416                                  bool IsPCRel, bool IsRelocWithSymbol,
417                                  int64_t Addend);
418  };
419}
420
421ELFObjectWriter::~ELFObjectWriter()
422{}
423
424// Emit the ELF header.
425void ELFObjectWriter::WriteHeader(uint64_t SectionDataSize,
426                                  unsigned NumberOfSections) {
427  // ELF Header
428  // ----------
429  //
430  // Note
431  // ----
432  // emitWord method behaves differently for ELF32 and ELF64, writing
433  // 4 bytes in the former and 8 in the latter.
434
435  Write8(0x7f); // e_ident[EI_MAG0]
436  Write8('E');  // e_ident[EI_MAG1]
437  Write8('L');  // e_ident[EI_MAG2]
438  Write8('F');  // e_ident[EI_MAG3]
439
440  Write8(Is64Bit ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
441
442  // e_ident[EI_DATA]
443  Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
444
445  Write8(ELF::EV_CURRENT);        // e_ident[EI_VERSION]
446  // e_ident[EI_OSABI]
447  switch (OSType) {
448    case Triple::FreeBSD:  Write8(ELF::ELFOSABI_FREEBSD); break;
449    case Triple::Linux:    Write8(ELF::ELFOSABI_LINUX); break;
450    default:               Write8(ELF::ELFOSABI_NONE); break;
451  }
452  Write8(0);                  // e_ident[EI_ABIVERSION]
453
454  WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
455
456  Write16(ELF::ET_REL);             // e_type
457
458  Write16(EMachine); // e_machine = target
459
460  Write32(ELF::EV_CURRENT);         // e_version
461  WriteWord(0);                    // e_entry, no entry point in .o file
462  WriteWord(0);                    // e_phoff, no program header for .o
463  WriteWord(SectionDataSize + (Is64Bit ? sizeof(ELF::Elf64_Ehdr) :
464            sizeof(ELF::Elf32_Ehdr)));  // e_shoff = sec hdr table off in bytes
465
466  // FIXME: Make this configurable.
467  Write32(0);   // e_flags = whatever the target wants
468
469  // e_ehsize = ELF header size
470  Write16(Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr));
471
472  Write16(0);                  // e_phentsize = prog header entry size
473  Write16(0);                  // e_phnum = # prog header entries = 0
474
475  // e_shentsize = Section header entry size
476  Write16(Is64Bit ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr));
477
478  // e_shnum     = # of section header ents
479  if (NumberOfSections >= ELF::SHN_LORESERVE)
480    Write16(0);
481  else
482    Write16(NumberOfSections);
483
484  // e_shstrndx  = Section # of '.shstrtab'
485  if (NumberOfSections >= ELF::SHN_LORESERVE)
486    Write16(ELF::SHN_XINDEX);
487  else
488    Write16(ShstrtabIndex);
489}
490
491void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF,
492                                       MCDataFragment *ShndxF,
493                                       uint64_t name,
494                                       uint8_t info, uint64_t value,
495                                       uint64_t size, uint8_t other,
496                                       uint32_t shndx,
497                                       bool Reserved) {
498  if (ShndxF) {
499    if (shndx >= ELF::SHN_LORESERVE && !Reserved)
500      String32(*ShndxF, shndx);
501    else
502      String32(*ShndxF, 0);
503  }
504
505  uint16_t Index = (shndx >= ELF::SHN_LORESERVE && !Reserved) ?
506    uint16_t(ELF::SHN_XINDEX) : shndx;
507
508  if (Is64Bit) {
509    String32(*SymtabF, name);  // st_name
510    String8(*SymtabF, info);   // st_info
511    String8(*SymtabF, other);  // st_other
512    String16(*SymtabF, Index); // st_shndx
513    String64(*SymtabF, value); // st_value
514    String64(*SymtabF, size);  // st_size
515  } else {
516    String32(*SymtabF, name);  // st_name
517    String32(*SymtabF, value); // st_value
518    String32(*SymtabF, size);  // st_size
519    String8(*SymtabF, info);   // st_info
520    String8(*SymtabF, other);  // st_other
521    String16(*SymtabF, Index); // st_shndx
522  }
523}
524
525static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout) {
526  if (Data.isCommon() && Data.isExternal())
527    return Data.getCommonAlignment();
528
529  const MCSymbol &Symbol = Data.getSymbol();
530  if (!Symbol.isInSection())
531    return 0;
532
533  if (Data.getFragment())
534    return Layout.getSymbolOffset(&Data);
535
536  return 0;
537}
538
539void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
540                                               const MCAsmLayout &Layout) {
541  // The presence of symbol versions causes undefined symbols and
542  // versions declared with @@@ to be renamed.
543
544  for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
545         ie = Asm.symbol_end(); it != ie; ++it) {
546    const MCSymbol &Alias = it->getSymbol();
547    const MCSymbol &Symbol = Alias.AliasedSymbol();
548    MCSymbolData &SD = Asm.getSymbolData(Symbol);
549
550    // Not an alias.
551    if (&Symbol == &Alias)
552      continue;
553
554    StringRef AliasName = Alias.getName();
555    size_t Pos = AliasName.find('@');
556    if (Pos == StringRef::npos)
557      continue;
558
559    // Aliases defined with .symvar copy the binding from the symbol they alias.
560    // This is the first place we are able to copy this information.
561    it->setExternal(SD.isExternal());
562    SetBinding(*it, GetBinding(SD));
563
564    StringRef Rest = AliasName.substr(Pos);
565    if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
566      continue;
567
568    // FIXME: produce a better error message.
569    if (Symbol.isUndefined() && Rest.startswith("@@") &&
570        !Rest.startswith("@@@"))
571      report_fatal_error("A @@ version cannot be undefined");
572
573    Renames.insert(std::make_pair(&Symbol, &Alias));
574  }
575}
576
577void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
578                                  MCDataFragment *ShndxF,
579                                  ELFSymbolData &MSD,
580                                  const MCAsmLayout &Layout) {
581  MCSymbolData &OrigData = *MSD.SymbolData;
582  MCSymbolData &Data =
583    Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
584
585  bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
586    Data.getSymbol().isVariable();
587
588  uint8_t Binding = GetBinding(OrigData);
589  uint8_t Visibility = GetVisibility(OrigData);
590  uint8_t Type = GetType(Data);
591
592  uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
593  uint8_t Other = Visibility;
594
595  uint64_t Value = SymbolValue(Data, Layout);
596  uint64_t Size = 0;
597  const MCExpr *ESize;
598
599  assert(!(Data.isCommon() && !Data.isExternal()));
600
601  ESize = Data.getSize();
602  if (Data.getSize()) {
603    MCValue Res;
604    if (ESize->getKind() == MCExpr::Binary) {
605      const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(ESize);
606
607      if (BE->EvaluateAsRelocatable(Res, &Layout)) {
608        assert(!Res.getSymA() || !Res.getSymA()->getSymbol().isDefined());
609        assert(!Res.getSymB() || !Res.getSymB()->getSymbol().isDefined());
610        Size = Res.getConstant();
611      }
612    } else if (ESize->getKind() == MCExpr::Constant) {
613      Size = static_cast<const MCConstantExpr *>(ESize)->getValue();
614    } else {
615      assert(0 && "Unsupported size expression");
616    }
617  }
618
619  // Write out the symbol table entry
620  WriteSymbolEntry(SymtabF, ShndxF, MSD.StringIndex, Info, Value,
621                   Size, Other, MSD.SectionIndex, IsReserved);
622}
623
624void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
625                                       MCDataFragment *ShndxF,
626                                       const MCAssembler &Asm,
627                                       const MCAsmLayout &Layout,
628                                     const SectionIndexMapTy &SectionIndexMap) {
629  // The string table must be emitted first because we need the index
630  // into the string table for all the symbol names.
631  assert(StringTable.size() && "Missing string table");
632
633  // FIXME: Make sure the start of the symbol table is aligned.
634
635  // The first entry is the undefined symbol entry.
636  WriteSymbolEntry(SymtabF, ShndxF, 0, 0, 0, 0, 0, 0, false);
637
638  // Write the symbol table entries.
639  LastLocalSymbolIndex = LocalSymbolData.size() + 1;
640  for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) {
641    ELFSymbolData &MSD = LocalSymbolData[i];
642    WriteSymbol(SymtabF, ShndxF, MSD, Layout);
643  }
644
645  // Write out a symbol table entry for each regular section.
646  for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e;
647       ++i) {
648    const MCSectionELF &Section =
649      static_cast<const MCSectionELF&>(i->getSection());
650    if (Section.getType() == ELF::SHT_RELA ||
651        Section.getType() == ELF::SHT_REL ||
652        Section.getType() == ELF::SHT_STRTAB ||
653        Section.getType() == ELF::SHT_SYMTAB)
654      continue;
655    WriteSymbolEntry(SymtabF, ShndxF, 0, ELF::STT_SECTION, 0, 0,
656                     ELF::STV_DEFAULT, SectionIndexMap.lookup(&Section), false);
657    LastLocalSymbolIndex++;
658  }
659
660  for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) {
661    ELFSymbolData &MSD = ExternalSymbolData[i];
662    MCSymbolData &Data = *MSD.SymbolData;
663    assert(((Data.getFlags() & ELF_STB_Global) ||
664            (Data.getFlags() & ELF_STB_Weak)) &&
665           "External symbol requires STB_GLOBAL or STB_WEAK flag");
666    WriteSymbol(SymtabF, ShndxF, MSD, Layout);
667    if (GetBinding(Data) == ELF::STB_LOCAL)
668      LastLocalSymbolIndex++;
669  }
670
671  for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) {
672    ELFSymbolData &MSD = UndefinedSymbolData[i];
673    MCSymbolData &Data = *MSD.SymbolData;
674    WriteSymbol(SymtabF, ShndxF, MSD, Layout);
675    if (GetBinding(Data) == ELF::STB_LOCAL)
676      LastLocalSymbolIndex++;
677  }
678}
679
680const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
681                                               const MCValue &Target,
682                                               const MCFragment &F) const {
683  const MCSymbol &Symbol = Target.getSymA()->getSymbol();
684  const MCSymbol &ASymbol = Symbol.AliasedSymbol();
685  const MCSymbol *Renamed = Renames.lookup(&Symbol);
686  const MCSymbolData &SD = Asm.getSymbolData(Symbol);
687
688  if (ASymbol.isUndefined()) {
689    if (Renamed)
690      return Renamed;
691    return &ASymbol;
692  }
693
694  if (SD.isExternal()) {
695    if (Renamed)
696      return Renamed;
697    return &Symbol;
698  }
699
700  const MCSectionELF &Section =
701    static_cast<const MCSectionELF&>(ASymbol.getSection());
702  const SectionKind secKind = Section.getKind();
703
704  if (secKind.isBSS())
705    return NULL;
706
707  if (secKind.isThreadLocal()) {
708    if (Renamed)
709      return Renamed;
710    return &Symbol;
711  }
712
713  MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
714  const MCSectionELF &Sec2 =
715    static_cast<const MCSectionELF&>(F.getParent()->getSection());
716
717  if (&Sec2 != &Section &&
718      (Kind == MCSymbolRefExpr::VK_PLT ||
719       Kind == MCSymbolRefExpr::VK_GOTPCREL ||
720       Kind == MCSymbolRefExpr::VK_GOTOFF)) {
721    if (Renamed)
722      return Renamed;
723    return &Symbol;
724  }
725
726  if (Section.getFlags() & MCSectionELF::SHF_MERGE) {
727    if (Target.getConstant() == 0)
728      return NULL;
729    if (Renamed)
730      return Renamed;
731    return &Symbol;
732  }
733
734  return NULL;
735}
736
737
738void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
739                                       const MCAsmLayout &Layout,
740                                       const MCFragment *Fragment,
741                                       const MCFixup &Fixup,
742                                       MCValue Target,
743                                       uint64_t &FixedValue) {
744  int64_t Addend = 0;
745  int Index = 0;
746  int64_t Value = Target.getConstant();
747  const MCSymbol *RelocSymbol = NULL;
748
749  bool IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
750  if (!Target.isAbsolute()) {
751    const MCSymbol &Symbol = Target.getSymA()->getSymbol();
752    const MCSymbol &ASymbol = Symbol.AliasedSymbol();
753    RelocSymbol = SymbolToReloc(Asm, Target, *Fragment);
754
755    if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
756      const MCSymbol &SymbolB = RefB->getSymbol();
757      MCSymbolData &SDB = Asm.getSymbolData(SymbolB);
758      IsPCRel = true;
759
760      // Offset of the symbol in the section
761      int64_t a = Layout.getSymbolOffset(&SDB);
762
763      // Ofeset of the relocation in the section
764      int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
765      Value += b - a;
766    }
767
768    if (!RelocSymbol) {
769      MCSymbolData &SD = Asm.getSymbolData(ASymbol);
770      MCFragment *F = SD.getFragment();
771
772      Index = F->getParent()->getOrdinal() + 1;
773
774      // Offset of the symbol in the section
775      Value += Layout.getSymbolOffset(&SD);
776    } else {
777      if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
778        WeakrefUsedInReloc.insert(RelocSymbol);
779      else
780        UsedInReloc.insert(RelocSymbol);
781      Index = -1;
782    }
783    Addend = Value;
784    // Compensate for the addend on i386.
785    if (Is64Bit)
786      Value = 0;
787  }
788
789  FixedValue = Value;
790  unsigned Type = GetRelocType(Target, Fixup, IsPCRel,
791                               (RelocSymbol != 0), Addend);
792
793  uint64_t RelocOffset = Layout.getFragmentOffset(Fragment) +
794    Fixup.getOffset();
795
796  if (!HasRelocationAddend) Addend = 0;
797  ELFRelocationEntry ERE(RelocOffset, Index, Type, RelocSymbol, Addend);
798  Relocations[Fragment->getParent()].push_back(ERE);
799}
800
801
802uint64_t
803ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
804                                             const MCSymbol *S) {
805  MCSymbolData &SD = Asm.getSymbolData(*S);
806  return SD.getIndex();
807}
808
809static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
810                       bool Used, bool Renamed) {
811  if (Data.getFlags() & ELF_Other_Weakref)
812    return false;
813
814  if (Used)
815    return true;
816
817  if (Renamed)
818    return false;
819
820  const MCSymbol &Symbol = Data.getSymbol();
821
822  if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
823    return true;
824
825  const MCSymbol &A = Symbol.AliasedSymbol();
826  if (!A.isVariable() && A.isUndefined() && !Data.isCommon())
827    return false;
828
829  if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
830    return false;
831
832  if (Symbol.isTemporary())
833    return false;
834
835  return true;
836}
837
838static bool isLocal(const MCSymbolData &Data, bool isSignature,
839                    bool isUsedInReloc) {
840  if (Data.isExternal())
841    return false;
842
843  const MCSymbol &Symbol = Data.getSymbol();
844  const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
845
846  if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
847    if (isSignature && !isUsedInReloc)
848      return true;
849
850    return false;
851  }
852
853  return true;
854}
855
856void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
857                                      SectionIndexMapTy &SectionIndexMap) {
858  unsigned Index = 1;
859  for (MCAssembler::iterator it = Asm.begin(),
860         ie = Asm.end(); it != ie; ++it) {
861    const MCSectionELF &Section =
862      static_cast<const MCSectionELF &>(it->getSection());
863    if (Section.getType() != ELF::SHT_GROUP)
864      continue;
865    SectionIndexMap[&Section] = Index++;
866  }
867
868  for (MCAssembler::iterator it = Asm.begin(),
869         ie = Asm.end(); it != ie; ++it) {
870    const MCSectionELF &Section =
871      static_cast<const MCSectionELF &>(it->getSection());
872    if (Section.getType() == ELF::SHT_GROUP)
873      continue;
874    SectionIndexMap[&Section] = Index++;
875  }
876}
877
878void ELFObjectWriter::ComputeSymbolTable(MCAssembler &Asm,
879                                      const SectionIndexMapTy &SectionIndexMap,
880                                      RevGroupMapTy RevGroupMap) {
881  // FIXME: Is this the correct place to do this?
882  if (NeedsGOT) {
883    llvm::StringRef Name = "_GLOBAL_OFFSET_TABLE_";
884    MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name);
885    MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym);
886    Data.setExternal(true);
887    SetBinding(Data, ELF::STB_GLOBAL);
888  }
889
890  // Build section lookup table.
891  int NumRegularSections = Asm.size();
892
893  // Index 0 is always the empty string.
894  StringMap<uint64_t> StringIndexMap;
895  StringTable += '\x00';
896
897  // Add the data for the symbols.
898  for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
899         ie = Asm.symbol_end(); it != ie; ++it) {
900    const MCSymbol &Symbol = it->getSymbol();
901
902    bool Used = UsedInReloc.count(&Symbol);
903    bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
904    bool isSignature = RevGroupMap.count(&Symbol);
905
906    if (!isInSymtab(Asm, *it,
907                    Used || WeakrefUsed || isSignature,
908                    Renames.count(&Symbol)))
909      continue;
910
911    ELFSymbolData MSD;
912    MSD.SymbolData = it;
913    const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
914
915    // Undefined symbols are global, but this is the first place we
916    // are able to set it.
917    bool Local = isLocal(*it, isSignature, Used);
918    if (!Local && GetBinding(*it) == ELF::STB_LOCAL) {
919      MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
920      SetBinding(*it, ELF::STB_GLOBAL);
921      SetBinding(SD, ELF::STB_GLOBAL);
922    }
923
924    if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
925      SetBinding(*it, ELF::STB_WEAK);
926
927    if (it->isCommon()) {
928      assert(!Local);
929      MSD.SectionIndex = ELF::SHN_COMMON;
930    } else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
931      MSD.SectionIndex = ELF::SHN_ABS;
932    } else if (RefSymbol.isUndefined()) {
933      if (isSignature && !Used)
934        MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
935      else
936        MSD.SectionIndex = ELF::SHN_UNDEF;
937    } else {
938      const MCSectionELF &Section =
939        static_cast<const MCSectionELF&>(RefSymbol.getSection());
940      MSD.SectionIndex = SectionIndexMap.lookup(&Section);
941      if (MSD.SectionIndex >= ELF::SHN_LORESERVE)
942        NeedsSymtabShndx = true;
943      assert(MSD.SectionIndex && "Invalid section index!");
944    }
945
946    // The @@@ in symbol version is replaced with @ in undefined symbols and
947    // @@ in defined ones.
948    StringRef Name = Symbol.getName();
949    SmallString<32> Buf;
950
951    size_t Pos = Name.find("@@@");
952    if (Pos != StringRef::npos) {
953      Buf += Name.substr(0, Pos);
954      unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1;
955      Buf += Name.substr(Pos + Skip);
956      Name = Buf;
957    }
958
959    uint64_t &Entry = StringIndexMap[Name];
960    if (!Entry) {
961      Entry = StringTable.size();
962      StringTable += Name;
963      StringTable += '\x00';
964    }
965    MSD.StringIndex = Entry;
966    if (MSD.SectionIndex == ELF::SHN_UNDEF)
967      UndefinedSymbolData.push_back(MSD);
968    else if (Local)
969      LocalSymbolData.push_back(MSD);
970    else
971      ExternalSymbolData.push_back(MSD);
972  }
973
974  // Symbols are required to be in lexicographic order.
975  array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end());
976  array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
977  array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
978
979  // Set the symbol indices. Local symbols must come before all other
980  // symbols with non-local bindings.
981  unsigned Index = 1;
982  for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
983    LocalSymbolData[i].SymbolData->setIndex(Index++);
984
985  Index += NumRegularSections;
986
987  for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
988    ExternalSymbolData[i].SymbolData->setIndex(Index++);
989  for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
990    UndefinedSymbolData[i].SymbolData->setIndex(Index++);
991}
992
993void ELFObjectWriter::WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
994                                      const MCSectionData &SD) {
995  if (!Relocations[&SD].empty()) {
996    MCContext &Ctx = Asm.getContext();
997    const MCSectionELF *RelaSection;
998    const MCSectionELF &Section =
999      static_cast<const MCSectionELF&>(SD.getSection());
1000
1001    const StringRef SectionName = Section.getSectionName();
1002    std::string RelaSectionName = HasRelocationAddend ? ".rela" : ".rel";
1003    RelaSectionName += SectionName;
1004
1005    unsigned EntrySize;
1006    if (HasRelocationAddend)
1007      EntrySize = Is64Bit ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela);
1008    else
1009      EntrySize = Is64Bit ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel);
1010
1011    RelaSection = Ctx.getELFSection(RelaSectionName, HasRelocationAddend ?
1012                                    ELF::SHT_RELA : ELF::SHT_REL, 0,
1013                                    SectionKind::getReadOnly(),
1014                                    EntrySize, "");
1015
1016    MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
1017    RelaSD.setAlignment(Is64Bit ? 8 : 4);
1018
1019    MCDataFragment *F = new MCDataFragment(&RelaSD);
1020
1021    WriteRelocationsFragment(Asm, F, &SD);
1022  }
1023}
1024
1025void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type,
1026                                       uint64_t Flags, uint64_t Address,
1027                                       uint64_t Offset, uint64_t Size,
1028                                       uint32_t Link, uint32_t Info,
1029                                       uint64_t Alignment,
1030                                       uint64_t EntrySize) {
1031  Write32(Name);        // sh_name: index into string table
1032  Write32(Type);        // sh_type
1033  WriteWord(Flags);     // sh_flags
1034  WriteWord(Address);   // sh_addr
1035  WriteWord(Offset);    // sh_offset
1036  WriteWord(Size);      // sh_size
1037  Write32(Link);        // sh_link
1038  Write32(Info);        // sh_info
1039  WriteWord(Alignment); // sh_addralign
1040  WriteWord(EntrySize); // sh_entsize
1041}
1042
1043void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
1044                                               MCDataFragment *F,
1045                                               const MCSectionData *SD) {
1046  std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
1047  // sort by the r_offset just like gnu as does
1048  array_pod_sort(Relocs.begin(), Relocs.end());
1049
1050  for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
1051    ELFRelocationEntry entry = Relocs[e - i - 1];
1052
1053    if (!entry.Index)
1054      ;
1055    else if (entry.Index < 0)
1056      entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol);
1057    else
1058      entry.Index += LocalSymbolData.size();
1059    if (Is64Bit) {
1060      String64(*F, entry.r_offset);
1061
1062      struct ELF::Elf64_Rela ERE64;
1063      ERE64.setSymbolAndType(entry.Index, entry.Type);
1064      String64(*F, ERE64.r_info);
1065
1066      if (HasRelocationAddend)
1067        String64(*F, entry.r_addend);
1068    } else {
1069      String32(*F, entry.r_offset);
1070
1071      struct ELF::Elf32_Rela ERE32;
1072      ERE32.setSymbolAndType(entry.Index, entry.Type);
1073      String32(*F, ERE32.r_info);
1074
1075      if (HasRelocationAddend)
1076        String32(*F, entry.r_addend);
1077    }
1078  }
1079}
1080
1081void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
1082                                             MCAsmLayout &Layout,
1083                                    const SectionIndexMapTy &SectionIndexMap) {
1084  MCContext &Ctx = Asm.getContext();
1085  MCDataFragment *F;
1086
1087  unsigned EntrySize = Is64Bit ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
1088
1089  // We construct .shstrtab, .symtab and .strtab in this order to match gnu as.
1090  const MCSectionELF *ShstrtabSection =
1091    Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0,
1092                      SectionKind::getReadOnly());
1093  MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
1094  ShstrtabSD.setAlignment(1);
1095  ShstrtabIndex = Asm.size();
1096
1097  const MCSectionELF *SymtabSection =
1098    Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
1099                      SectionKind::getReadOnly(),
1100                      EntrySize, "");
1101  MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
1102  SymtabSD.setAlignment(Is64Bit ? 8 : 4);
1103  SymbolTableIndex = Asm.size();
1104
1105  MCSectionData *SymtabShndxSD = NULL;
1106
1107  if (NeedsSymtabShndx) {
1108    const MCSectionELF *SymtabShndxSection =
1109      Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0,
1110                        SectionKind::getReadOnly(), 4, "");
1111    SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection);
1112    SymtabShndxSD->setAlignment(4);
1113  }
1114
1115  const MCSection *StrtabSection;
1116  StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
1117                                    SectionKind::getReadOnly());
1118  MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
1119  StrtabSD.setAlignment(1);
1120  StringTableIndex = Asm.size();
1121
1122  WriteRelocations(Asm, Layout);
1123
1124  // Symbol table
1125  F = new MCDataFragment(&SymtabSD);
1126  MCDataFragment *ShndxF = NULL;
1127  if (NeedsSymtabShndx) {
1128    ShndxF = new MCDataFragment(SymtabShndxSD);
1129  }
1130  WriteSymbolTable(F, ShndxF, Asm, Layout, SectionIndexMap);
1131
1132  F = new MCDataFragment(&StrtabSD);
1133  F->getContents().append(StringTable.begin(), StringTable.end());
1134
1135  F = new MCDataFragment(&ShstrtabSD);
1136
1137  // Section header string table.
1138  //
1139  // The first entry of a string table holds a null character so skip
1140  // section 0.
1141  uint64_t Index = 1;
1142  F->getContents() += '\x00';
1143
1144  StringMap<uint64_t> SecStringMap;
1145  for (MCAssembler::const_iterator it = Asm.begin(),
1146         ie = Asm.end(); it != ie; ++it) {
1147    const MCSectionELF &Section =
1148      static_cast<const MCSectionELF&>(it->getSection());
1149    // FIXME: We could merge suffixes like in .text and .rela.text.
1150
1151    StringRef Name = Section.getSectionName();
1152    if (SecStringMap.count(Name)) {
1153      SectionStringTableIndex[&Section] =  SecStringMap[Name];
1154      continue;
1155    }
1156    // Remember the index into the string table so we can write it
1157    // into the sh_name field of the section header table.
1158    SectionStringTableIndex[&Section] = Index;
1159    SecStringMap[Name] = Index;
1160
1161    Index += Name.size() + 1;
1162    F->getContents() += Name;
1163    F->getContents() += '\x00';
1164  }
1165}
1166
1167bool ELFObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
1168                                           const MCValue Target,
1169                                           bool IsPCRel,
1170                                           const MCFragment *DF) const {
1171  // If this is a PCrel relocation, find the section this fixup value is
1172  // relative to.
1173  const MCSection *BaseSection = 0;
1174  if (IsPCRel) {
1175    BaseSection = &DF->getParent()->getSection();
1176    assert(BaseSection);
1177  }
1178
1179  const MCSection *SectionA = 0;
1180  const MCSymbol *SymbolA = 0;
1181  if (const MCSymbolRefExpr *A = Target.getSymA()) {
1182    SymbolA = &A->getSymbol();
1183    SectionA = &SymbolA->AliasedSymbol().getSection();
1184  }
1185
1186  const MCSection *SectionB = 0;
1187  const MCSymbol *SymbolB = 0;
1188  if (const MCSymbolRefExpr *B = Target.getSymB()) {
1189    SymbolB = &B->getSymbol();
1190    SectionB = &SymbolB->AliasedSymbol().getSection();
1191  }
1192
1193  if (!BaseSection)
1194    return SectionA == SectionB;
1195
1196  if (SymbolB)
1197    return false;
1198
1199  // Absolute address but PCrel instruction, so we need a relocation.
1200  if (!SymbolA)
1201    return false;
1202
1203  // FIXME: This is in here just to match gnu as output. If the two ends
1204  // are in the same section, there is nothing that the linker can do to
1205  // break it.
1206  const MCSymbolData &DataA = Asm.getSymbolData(*SymbolA);
1207  if (DataA.isExternal())
1208    return false;
1209
1210  return BaseSection == SectionA;
1211}
1212
1213void ELFObjectWriter::CreateGroupSections(MCAssembler &Asm,
1214                                          MCAsmLayout &Layout,
1215                                          GroupMapTy &GroupMap,
1216                                          RevGroupMapTy &RevGroupMap) {
1217  // Build the groups
1218  for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1219       it != ie; ++it) {
1220    const MCSectionELF &Section =
1221      static_cast<const MCSectionELF&>(it->getSection());
1222    if (!(Section.getFlags() & MCSectionELF::SHF_GROUP))
1223      continue;
1224
1225    const MCSymbol *SignatureSymbol = Section.getGroup();
1226    Asm.getOrCreateSymbolData(*SignatureSymbol);
1227    const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
1228    if (!Group) {
1229      Group = Asm.getContext().CreateELFGroupSection();
1230      MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1231      Data.setAlignment(4);
1232      MCDataFragment *F = new MCDataFragment(&Data);
1233      String32(*F, ELF::GRP_COMDAT);
1234    }
1235    GroupMap[Group] = SignatureSymbol;
1236  }
1237
1238  // Add sections to the groups
1239  unsigned Index = 1;
1240  unsigned NumGroups = RevGroupMap.size();
1241  for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
1242       it != ie; ++it, ++Index) {
1243    const MCSectionELF &Section =
1244      static_cast<const MCSectionELF&>(it->getSection());
1245    if (!(Section.getFlags() & MCSectionELF::SHF_GROUP))
1246      continue;
1247    const MCSectionELF *Group = RevGroupMap[Section.getGroup()];
1248    MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
1249    // FIXME: we could use the previous fragment
1250    MCDataFragment *F = new MCDataFragment(&Data);
1251    String32(*F, NumGroups + Index);
1252  }
1253}
1254
1255void ELFObjectWriter::WriteSection(MCAssembler &Asm,
1256                                   const SectionIndexMapTy &SectionIndexMap,
1257                                   uint32_t GroupSymbolIndex,
1258                                   uint64_t Offset, uint64_t Size,
1259                                   uint64_t Alignment,
1260                                   const MCSectionELF &Section) {
1261  uint64_t sh_link = 0;
1262  uint64_t sh_info = 0;
1263
1264  switch(Section.getType()) {
1265  case ELF::SHT_DYNAMIC:
1266    sh_link = SectionStringTableIndex[&Section];
1267    sh_info = 0;
1268    break;
1269
1270  case ELF::SHT_REL:
1271  case ELF::SHT_RELA: {
1272    const MCSectionELF *SymtabSection;
1273    const MCSectionELF *InfoSection;
1274    SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB,
1275                                                   0,
1276                                                   SectionKind::getReadOnly());
1277    sh_link = SectionIndexMap.lookup(SymtabSection);
1278    assert(sh_link && ".symtab not found");
1279
1280    // Remove ".rel" and ".rela" prefixes.
1281    unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
1282    StringRef SectionName = Section.getSectionName().substr(SecNameLen);
1283
1284    InfoSection = Asm.getContext().getELFSection(SectionName,
1285                                                 ELF::SHT_PROGBITS, 0,
1286                                                 SectionKind::getReadOnly());
1287    sh_info = SectionIndexMap.lookup(InfoSection);
1288    break;
1289  }
1290
1291  case ELF::SHT_SYMTAB:
1292  case ELF::SHT_DYNSYM:
1293    sh_link = StringTableIndex;
1294    sh_info = LastLocalSymbolIndex;
1295    break;
1296
1297  case ELF::SHT_SYMTAB_SHNDX:
1298    sh_link = SymbolTableIndex;
1299    break;
1300
1301  case ELF::SHT_PROGBITS:
1302  case ELF::SHT_STRTAB:
1303  case ELF::SHT_NOBITS:
1304  case ELF::SHT_NULL:
1305  case ELF::SHT_ARM_ATTRIBUTES:
1306    // Nothing to do.
1307    break;
1308
1309  case ELF::SHT_GROUP: {
1310    sh_link = SymbolTableIndex;
1311    sh_info = GroupSymbolIndex;
1312    break;
1313  }
1314
1315  default:
1316    assert(0 && "FIXME: sh_type value not supported!");
1317    break;
1318  }
1319
1320  WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(),
1321                   Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
1322                   Alignment, Section.getEntrySize());
1323}
1324
1325static bool IsELFMetaDataSection(const MCSectionData &SD) {
1326  return SD.getOrdinal() == ~UINT32_C(0) &&
1327    !SD.getSection().isVirtualSection();
1328}
1329
1330static uint64_t DataSectionSize(const MCSectionData &SD) {
1331  uint64_t Ret = 0;
1332  for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1333       ++i) {
1334    const MCFragment &F = *i;
1335    assert(F.getKind() == MCFragment::FT_Data);
1336    Ret += cast<MCDataFragment>(F).getContents().size();
1337  }
1338  return Ret;
1339}
1340
1341static uint64_t GetSectionFileSize(const MCAsmLayout &Layout,
1342                                   const MCSectionData &SD) {
1343  if (IsELFMetaDataSection(SD))
1344    return DataSectionSize(SD);
1345  return Layout.getSectionFileSize(&SD);
1346}
1347
1348static uint64_t GetSectionAddressSize(const MCAsmLayout &Layout,
1349                                      const MCSectionData &SD) {
1350  if (IsELFMetaDataSection(SD))
1351    return DataSectionSize(SD);
1352  return Layout.getSectionAddressSize(&SD);
1353}
1354
1355static void WriteDataSectionData(ELFObjectWriter *W, const MCSectionData &SD) {
1356  for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
1357       ++i) {
1358    const MCFragment &F = *i;
1359    assert(F.getKind() == MCFragment::FT_Data);
1360    W->WriteBytes(cast<MCDataFragment>(F).getContents().str());
1361  }
1362}
1363
1364void ELFObjectWriter::WriteObject(MCAssembler &Asm,
1365                                  const MCAsmLayout &Layout) {
1366  GroupMapTy GroupMap;
1367  RevGroupMapTy RevGroupMap;
1368  CreateGroupSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
1369                      RevGroupMap);
1370
1371  SectionIndexMapTy SectionIndexMap;
1372
1373  ComputeIndexMap(Asm, SectionIndexMap);
1374
1375  // Compute symbol table information.
1376  ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap);
1377
1378  CreateMetadataSections(const_cast<MCAssembler&>(Asm),
1379                         const_cast<MCAsmLayout&>(Layout),
1380                         SectionIndexMap);
1381
1382  // Update to include the metadata sections.
1383  ComputeIndexMap(Asm, SectionIndexMap);
1384
1385  // Add 1 for the null section.
1386  unsigned NumSections = Asm.size() + 1;
1387  uint64_t NaturalAlignment = Is64Bit ? 8 : 4;
1388  uint64_t HeaderSize = Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr);
1389  uint64_t FileOff = HeaderSize;
1390
1391  std::vector<const MCSectionELF*> Sections;
1392  Sections.resize(NumSections);
1393
1394  for (SectionIndexMapTy::const_iterator i=
1395         SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) {
1396    const std::pair<const MCSectionELF*, uint32_t> &p = *i;
1397    Sections[p.second] = p.first;
1398  }
1399
1400  for (unsigned i = 1; i < NumSections; ++i) {
1401    const MCSectionELF &Section = *Sections[i];
1402    const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1403
1404    FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
1405
1406    // Get the size of the section in the output file (including padding).
1407    FileOff += GetSectionFileSize(Layout, SD);
1408  }
1409
1410  FileOff = RoundUpToAlignment(FileOff, NaturalAlignment);
1411
1412  // Write out the ELF header ...
1413  WriteHeader(FileOff - HeaderSize, NumSections);
1414
1415  FileOff = HeaderSize;
1416
1417  // ... then all of the sections ...
1418  DenseMap<const MCSection*, uint64_t> SectionOffsetMap;
1419
1420  for (unsigned i = 1; i < NumSections; ++i) {
1421    const MCSectionELF &Section = *Sections[i];
1422    const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1423
1424    uint64_t Padding = OffsetToAlignment(FileOff, SD.getAlignment());
1425    WriteZeros(Padding);
1426    FileOff += Padding;
1427
1428    // Remember the offset into the file for this section.
1429    SectionOffsetMap[&Section] = FileOff;
1430
1431    FileOff += GetSectionFileSize(Layout, SD);
1432
1433    if (IsELFMetaDataSection(SD))
1434      WriteDataSectionData(this, SD);
1435    else
1436      Asm.WriteSectionData(&SD, Layout);
1437  }
1438
1439  uint64_t Padding = OffsetToAlignment(FileOff, NaturalAlignment);
1440  WriteZeros(Padding);
1441  FileOff += Padding;
1442
1443  // ... and then the section header table.
1444  // Should we align the section header table?
1445  //
1446  // Null section first.
1447  uint64_t FirstSectionSize =
1448    NumSections >= ELF::SHN_LORESERVE ? NumSections : 0;
1449  uint32_t FirstSectionLink =
1450    ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0;
1451  WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0);
1452
1453  for (unsigned i = 1; i < NumSections; ++i) {
1454    const MCSectionELF &Section = *Sections[i];
1455    const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
1456    uint32_t GroupSymbolIndex;
1457    if (Section.getType() != ELF::SHT_GROUP)
1458      GroupSymbolIndex = 0;
1459    else
1460      GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm, GroupMap[&Section]);
1461
1462    uint64_t Size = GetSectionAddressSize(Layout, SD);
1463
1464    WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
1465                 SectionOffsetMap[&Section], Size,
1466                 SD.getAlignment(), Section);
1467  }
1468}
1469
1470MCObjectWriter *llvm::createELFObjectWriter(raw_ostream &OS,
1471                                            bool Is64Bit,
1472                                            Triple::OSType OSType,
1473                                            uint16_t EMachine,
1474                                            bool IsLittleEndian,
1475                                            bool HasRelocationAddend) {
1476  switch (EMachine) {
1477    case ELF::EM_386:
1478    case ELF::EM_X86_64:
1479      return new X86ELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
1480                                    HasRelocationAddend, OSType); break;
1481    case ELF::EM_ARM:
1482      return new ARMELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
1483                                    HasRelocationAddend, OSType); break;
1484    case ELF::EM_MBLAZE:
1485      return new MBlazeELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
1486                                       HasRelocationAddend, OSType); break;
1487    default: llvm_unreachable("Unsupported architecture"); break;
1488  }
1489}
1490
1491
1492/// START OF SUBCLASSES for ELFObjectWriter
1493//===- ARMELFObjectWriter -------------------------------------------===//
1494
1495ARMELFObjectWriter::ARMELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
1496                                       bool _IsLittleEndian,
1497                                       uint16_t _EMachine, bool _HasRelocationAddend,
1498                                       Triple::OSType _OSType)
1499  : ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
1500                    _HasRelocationAddend, _OSType)
1501{}
1502
1503ARMELFObjectWriter::~ARMELFObjectWriter()
1504{}
1505
1506unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target,
1507                                          const MCFixup &Fixup,
1508                                          bool IsPCRel,
1509                                          bool IsRelocWithSymbol,
1510                                          int64_t Addend) {
1511  MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
1512    MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
1513
1514  unsigned Type = 0;
1515  if (IsPCRel) {
1516    switch ((unsigned)Fixup.getKind()) {
1517    default: assert(0 && "Unimplemented");
1518    case FK_Data_4:
1519      switch (Modifier) {
1520      default: llvm_unreachable("Unsupported Modifier");
1521      case MCSymbolRefExpr::VK_None:
1522        Type = ELF::R_ARM_BASE_PREL; break;
1523      case MCSymbolRefExpr::VK_ARM_TLSGD:
1524        assert(0 && "unimplemented"); break;
1525      case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
1526        Type = ELF::R_ARM_TLS_IE32;
1527      } break;
1528    case ARM::fixup_arm_branch:
1529      switch (Modifier) {
1530      case MCSymbolRefExpr::VK_ARM_PLT:
1531        Type = ELF::R_ARM_PLT32; break;
1532      default:
1533        Type = ELF::R_ARM_CALL; break;
1534      } break;
1535    }
1536  } else {
1537    switch ((unsigned)Fixup.getKind()) {
1538    default: llvm_unreachable("invalid fixup kind!");
1539    case FK_Data_4:
1540      switch (Modifier) {
1541      default: llvm_unreachable("Unsupported Modifier"); break;
1542      case MCSymbolRefExpr::VK_ARM_GOT:
1543        Type = ELF::R_ARM_GOT_BREL; break;
1544      case MCSymbolRefExpr::VK_ARM_TLSGD:
1545        Type = ELF::R_ARM_TLS_GD32; break;
1546      case MCSymbolRefExpr::VK_ARM_TPOFF:
1547        Type = ELF::R_ARM_TLS_LE32; break;
1548      case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
1549        Type = ELF::R_ARM_TLS_IE32; break;
1550      case MCSymbolRefExpr::VK_None:
1551        Type = ELF::R_ARM_ABS32; break;
1552      case MCSymbolRefExpr::VK_ARM_GOTOFF:
1553        Type = ELF::R_ARM_GOTOFF32; break;
1554      } break;
1555    case ARM::fixup_arm_ldst_pcrel_12:
1556    case ARM::fixup_arm_pcrel_10:
1557    case ARM::fixup_arm_adr_pcrel_12:
1558    case ARM::fixup_arm_thumb_bl:
1559    case ARM::fixup_arm_thumb_cb:
1560    case ARM::fixup_arm_thumb_cp:
1561    case ARM::fixup_arm_thumb_br:
1562      assert(0 && "Unimplemented"); break;
1563    case ARM::fixup_arm_branch:
1564      // FIXME: Differentiate between R_ARM_CALL and
1565      // R_ARM_JUMP24 (latter used for conditional jumps)
1566      Type = ELF::R_ARM_CALL; break;
1567    case ARM::fixup_arm_movt_hi16:
1568      Type = ELF::R_ARM_MOVT_ABS; break;
1569    case ARM::fixup_arm_movw_lo16:
1570      Type = ELF::R_ARM_MOVW_ABS_NC; break;
1571    }
1572  }
1573
1574  if (RelocNeedsGOT(Modifier))
1575    NeedsGOT = true;
1576
1577  return Type;
1578}
1579
1580//===- MBlazeELFObjectWriter -------------------------------------------===//
1581
1582MBlazeELFObjectWriter::MBlazeELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
1583                                             bool _IsLittleEndian,
1584                                             uint16_t _EMachine,
1585                                             bool _HasRelocationAddend,
1586                                             Triple::OSType _OSType)
1587  : ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
1588                    _HasRelocationAddend, _OSType) {
1589}
1590
1591MBlazeELFObjectWriter::~MBlazeELFObjectWriter() {
1592}
1593
1594unsigned MBlazeELFObjectWriter::GetRelocType(const MCValue &Target,
1595                                             const MCFixup &Fixup,
1596                                             bool IsPCRel,
1597                                             bool IsRelocWithSymbol,
1598                                             int64_t Addend) {
1599  // determine the type of the relocation
1600  unsigned Type;
1601  if (IsPCRel) {
1602    switch ((unsigned)Fixup.getKind()) {
1603    default:
1604      llvm_unreachable("Unimplemented");
1605    case FK_PCRel_4:
1606      Type = ELF::R_MICROBLAZE_64_PCREL;
1607      break;
1608    case FK_PCRel_2:
1609      Type = ELF::R_MICROBLAZE_32_PCREL;
1610      break;
1611    }
1612  } else {
1613    switch ((unsigned)Fixup.getKind()) {
1614    default: llvm_unreachable("invalid fixup kind!");
1615    case FK_Data_4:
1616      Type = ((IsRelocWithSymbol || Addend !=0)
1617              ? ELF::R_MICROBLAZE_32
1618              : ELF::R_MICROBLAZE_64);
1619      break;
1620    case FK_Data_2:
1621      Type = ELF::R_MICROBLAZE_32;
1622      break;
1623    }
1624  }
1625  return Type;
1626}
1627
1628//===- X86ELFObjectWriter -------------------------------------------===//
1629
1630
1631X86ELFObjectWriter::X86ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
1632                                       bool _IsLittleEndian,
1633                                       uint16_t _EMachine, bool _HasRelocationAddend,
1634                                       Triple::OSType _OSType)
1635  : ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
1636                    _HasRelocationAddend, _OSType)
1637{}
1638
1639X86ELFObjectWriter::~X86ELFObjectWriter()
1640{}
1641
1642unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
1643                                          const MCFixup &Fixup,
1644                                          bool IsPCRel,
1645                                          bool IsRelocWithSymbol,
1646                                          int64_t Addend) {
1647  // determine the type of the relocation
1648
1649  MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
1650    MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
1651  unsigned Type;
1652  if (Is64Bit) {
1653    if (IsPCRel) {
1654      switch (Modifier) {
1655      default:
1656        llvm_unreachable("Unimplemented");
1657      case MCSymbolRefExpr::VK_None:
1658        Type = ELF::R_X86_64_PC32;
1659        break;
1660      case MCSymbolRefExpr::VK_PLT:
1661        Type = ELF::R_X86_64_PLT32;
1662        break;
1663      case MCSymbolRefExpr::VK_GOTPCREL:
1664        Type = ELF::R_X86_64_GOTPCREL;
1665        break;
1666      case MCSymbolRefExpr::VK_GOTTPOFF:
1667        Type = ELF::R_X86_64_GOTTPOFF;
1668        break;
1669      case MCSymbolRefExpr::VK_TLSGD:
1670        Type = ELF::R_X86_64_TLSGD;
1671        break;
1672      case MCSymbolRefExpr::VK_TLSLD:
1673        Type = ELF::R_X86_64_TLSLD;
1674        break;
1675      }
1676    } else {
1677      switch ((unsigned)Fixup.getKind()) {
1678      default: llvm_unreachable("invalid fixup kind!");
1679      case FK_Data_8: Type = ELF::R_X86_64_64; break;
1680      case X86::reloc_signed_4byte:
1681      case FK_PCRel_4:
1682        assert(isInt<32>(Target.getConstant()));
1683        switch (Modifier) {
1684        default:
1685          llvm_unreachable("Unimplemented");
1686        case MCSymbolRefExpr::VK_None:
1687          Type = ELF::R_X86_64_32S;
1688          break;
1689        case MCSymbolRefExpr::VK_GOT:
1690          Type = ELF::R_X86_64_GOT32;
1691          break;
1692        case MCSymbolRefExpr::VK_GOTPCREL:
1693          Type = ELF::R_X86_64_GOTPCREL;
1694          break;
1695        case MCSymbolRefExpr::VK_TPOFF:
1696          Type = ELF::R_X86_64_TPOFF32;
1697          break;
1698        case MCSymbolRefExpr::VK_DTPOFF:
1699          Type = ELF::R_X86_64_DTPOFF32;
1700          break;
1701        }
1702        break;
1703      case FK_Data_4:
1704        Type = ELF::R_X86_64_32;
1705        break;
1706      case FK_Data_2: Type = ELF::R_X86_64_16; break;
1707      case FK_PCRel_1:
1708      case FK_Data_1: Type = ELF::R_X86_64_8; break;
1709      }
1710    }
1711  } else {
1712    if (IsPCRel) {
1713      switch (Modifier) {
1714      default:
1715        llvm_unreachable("Unimplemented");
1716      case MCSymbolRefExpr::VK_None:
1717        Type = ELF::R_386_PC32;
1718        break;
1719      case MCSymbolRefExpr::VK_PLT:
1720        Type = ELF::R_386_PLT32;
1721        break;
1722      }
1723    } else {
1724      switch ((unsigned)Fixup.getKind()) {
1725      default: llvm_unreachable("invalid fixup kind!");
1726
1727      case X86::reloc_global_offset_table:
1728        Type = ELF::R_386_GOTPC;
1729        break;
1730
1731      // FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode
1732      // instead?
1733      case X86::reloc_signed_4byte:
1734      case FK_PCRel_4:
1735      case FK_Data_4:
1736        switch (Modifier) {
1737        default:
1738          llvm_unreachable("Unimplemented");
1739        case MCSymbolRefExpr::VK_None:
1740          Type = ELF::R_386_32;
1741          break;
1742        case MCSymbolRefExpr::VK_GOT:
1743          Type = ELF::R_386_GOT32;
1744          break;
1745        case MCSymbolRefExpr::VK_GOTOFF:
1746          Type = ELF::R_386_GOTOFF;
1747          break;
1748        case MCSymbolRefExpr::VK_TLSGD:
1749          Type = ELF::R_386_TLS_GD;
1750          break;
1751        case MCSymbolRefExpr::VK_TPOFF:
1752          Type = ELF::R_386_TLS_LE_32;
1753          break;
1754        case MCSymbolRefExpr::VK_INDNTPOFF:
1755          Type = ELF::R_386_TLS_IE;
1756          break;
1757        case MCSymbolRefExpr::VK_NTPOFF:
1758          Type = ELF::R_386_TLS_LE;
1759          break;
1760        case MCSymbolRefExpr::VK_GOTNTPOFF:
1761          Type = ELF::R_386_TLS_GOTIE;
1762          break;
1763        case MCSymbolRefExpr::VK_TLSLDM:
1764          Type = ELF::R_386_TLS_LDM;
1765          break;
1766        case MCSymbolRefExpr::VK_DTPOFF:
1767          Type = ELF::R_386_TLS_LDO_32;
1768          break;
1769        }
1770        break;
1771      case FK_Data_2: Type = ELF::R_386_16; break;
1772      case FK_PCRel_1:
1773      case FK_Data_1: Type = ELF::R_386_8; break;
1774      }
1775    }
1776  }
1777
1778  if (RelocNeedsGOT(Modifier))
1779    NeedsGOT = true;
1780
1781  return Type;
1782}
1783