WinCOFFObjectWriter.cpp revision 9cf23a9ab466a900bc0f937bc930d398d6097766 
1//===-- llvm/MC/WinCOFFObjectWriter.cpp -------------------------*- C++ -*-===//
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 contains an implementation of a Win32 COFF object file writer.
11//
12//===----------------------------------------------------------------------===//
13
14#define DEBUG_TYPE "WinCOFFObjectWriter"
15
16#include "llvm/MC/MCObjectWriter.h"
17#include "llvm/MC/MCSection.h"
18#include "llvm/MC/MCContext.h"
19#include "llvm/MC/MCSymbol.h"
20#include "llvm/MC/MCExpr.h"
21#include "llvm/MC/MCValue.h"
22#include "llvm/MC/MCAssembler.h"
23#include "llvm/MC/MCAsmLayout.h"
24#include "llvm/MC/MCSectionCOFF.h"
25
26#include "llvm/ADT/DenseMap.h"
27#include "llvm/ADT/StringMap.h"
28#include "llvm/ADT/StringRef.h"
29
30#include "llvm/Support/COFF.h"
31#include "llvm/Support/Debug.h"
32#include "llvm/Support/ErrorHandling.h"
33
34#include "llvm/System/TimeValue.h"
35
36#include "../Target/X86/X86FixupKinds.h"
37
38#include <cstdio>
39
40using namespace llvm;
41
42namespace {
43typedef llvm::SmallString<COFF::NameSize> name;
44
45enum AuxiliaryType {
46  ATFunctionDefinition,
47  ATbfAndefSymbol,
48  ATWeakExternal,
49  ATFile,
50  ATSectionDefinition
51};
52
53struct AuxSymbol {
54  AuxiliaryType   AuxType;
55  COFF::Auxiliary Aux;
56};
57
58class COFFSymbol;
59class COFFSection;
60
61class COFFSymbol {
62public:
63  COFF::symbol Data;
64
65  typedef llvm::SmallVector<AuxSymbol, 1> AuxiliarySymbols;
66
67  name             Name;
68  int              Index;
69  AuxiliarySymbols Aux;
70  COFFSymbol      *Other;
71  COFFSection     *Section;
72  int              Relocations;
73
74  MCSymbolData const *MCData;
75
76  COFFSymbol(llvm::StringRef name);
77  size_t size() const;
78  void set_name_offset(uint32_t Offset);
79
80  bool should_keep() const;
81};
82
83// This class contains staging data for a COFF relocation entry.
84struct COFFRelocation {
85  COFF::relocation Data;
86  COFFSymbol          *Symb;
87
88  COFFRelocation() : Symb(NULL) {}
89  static size_t size() { return COFF::RelocationSize; }
90};
91
92typedef std::vector<COFFRelocation> relocations;
93
94class COFFSection {
95public:
96  COFF::section Header;
97
98  std::string          Name;
99  int                  Number;
100  MCSectionData const *MCData;
101  COFFSymbol          *Symbol;
102  relocations          Relocations;
103
104  COFFSection(llvm::StringRef name);
105  static size_t size();
106};
107
108// This class holds the COFF string table.
109class StringTable {
110  typedef llvm::StringMap<size_t> map;
111  map Map;
112
113  void update_length();
114public:
115  std::vector<char> Data;
116
117  StringTable();
118  size_t size() const;
119  size_t insert(llvm::StringRef String);
120};
121
122class WinCOFFObjectWriter : public MCObjectWriter {
123public:
124
125  typedef std::vector<COFFSymbol*>  symbols;
126  typedef std::vector<COFFSection*> sections;
127
128  typedef StringMap<COFFSymbol *>  name_symbol_map;
129  typedef StringMap<COFFSection *> name_section_map;
130
131  typedef DenseMap<MCSymbolData const *, COFFSymbol *>   symbol_map;
132  typedef DenseMap<MCSectionData const *, COFFSection *> section_map;
133
134  // Root level file contents.
135  bool Is64Bit;
136  COFF::header Header;
137  sections     Sections;
138  symbols      Symbols;
139  StringTable  Strings;
140
141  // Maps used during object file creation.
142  section_map SectionMap;
143  symbol_map  SymbolMap;
144
145  WinCOFFObjectWriter(raw_ostream &OS, bool is64Bit);
146  ~WinCOFFObjectWriter();
147
148  COFFSymbol *createSymbol(llvm::StringRef Name);
149  COFFSection *createSection(llvm::StringRef Name);
150
151  template <typename object_t, typename list_t>
152  object_t *createCOFFEntity(llvm::StringRef Name, list_t &List);
153
154  void DefineSection(MCSectionData const &SectionData);
155  void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler);
156
157  void MakeSymbolReal(COFFSymbol &S, size_t Index);
158  void MakeSectionReal(COFFSection &S, size_t Number);
159
160  bool ExportSection(COFFSection const *S);
161  bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm);
162
163  bool IsPhysicalSection(COFFSection *S);
164
165  // Entity writing methods.
166
167  void WriteFileHeader(const COFF::header &Header);
168  void WriteSymbol(const COFFSymbol *S);
169  void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
170  void WriteSectionHeader(const COFF::section &S);
171  void WriteRelocation(const COFF::relocation &R);
172
173  // MCObjectWriter interface implementation.
174
175  void ExecutePostLayoutBinding(MCAssembler &Asm);
176
177  void RecordRelocation(const MCAssembler &Asm,
178                        const MCAsmLayout &Layout,
179                        const MCFragment *Fragment,
180                        const MCFixup &Fixup,
181                        MCValue Target,
182                        uint64_t &FixedValue);
183
184  void WriteObject(const MCAssembler &Asm, const MCAsmLayout &Layout);
185};
186}
187
188static inline void write_uint32_le(void *Data, uint32_t const &Value) {
189  uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
190  Ptr[0] = (Value & 0x000000FF) >>  0;
191  Ptr[1] = (Value & 0x0000FF00) >>  8;
192  Ptr[2] = (Value & 0x00FF0000) >> 16;
193  Ptr[3] = (Value & 0xFF000000) >> 24;
194}
195
196static inline void write_uint16_le(void *Data, uint16_t const &Value) {
197  uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
198  Ptr[0] = (Value & 0x00FF) >> 0;
199  Ptr[1] = (Value & 0xFF00) >> 8;
200}
201
202static inline void write_uint8_le(void *Data, uint8_t const &Value) {
203  uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
204  Ptr[0] = (Value & 0xFF) >> 0;
205}
206
207//------------------------------------------------------------------------------
208// Symbol class implementation
209
210COFFSymbol::COFFSymbol(llvm::StringRef name)
211  : Name(name.begin(), name.end())
212  , Other(NULL)
213  , Section(NULL)
214  , Relocations(0)
215  , MCData(NULL) {
216  memset(&Data, 0, sizeof(Data));
217}
218
219size_t COFFSymbol::size() const {
220  return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
221}
222
223// In the case that the name does not fit within 8 bytes, the offset
224// into the string table is stored in the last 4 bytes instead, leaving
225// the first 4 bytes as 0.
226void COFFSymbol::set_name_offset(uint32_t Offset) {
227  write_uint32_le(Data.Name + 0, 0);
228  write_uint32_le(Data.Name + 4, Offset);
229}
230
231/// logic to decide if the symbol should be reported in the symbol table
232bool COFFSymbol::should_keep() const {
233  // no section means its external, keep it
234  if (Section == NULL)
235    return true;
236
237  // if it has relocations pointing at it, keep it
238  if (Relocations > 0)   {
239    assert(Section->Number != -1 && "Sections with relocations must be real!");
240    return true;
241  }
242
243  // if the section its in is being droped, drop it
244  if (Section->Number == -1)
245      return false;
246
247  // if it is the section symbol, keep it
248  if (Section->Symbol == this)
249    return true;
250
251  // if its temporary, drop it
252  if (MCData && MCData->getSymbol().isTemporary())
253      return false;
254
255  // otherwise, keep it
256  return true;
257}
258
259//------------------------------------------------------------------------------
260// Section class implementation
261
262COFFSection::COFFSection(llvm::StringRef name)
263  : Name(name)
264  , MCData(NULL)
265  , Symbol(NULL) {
266  memset(&Header, 0, sizeof(Header));
267}
268
269size_t COFFSection::size() {
270  return COFF::SectionSize;
271}
272
273//------------------------------------------------------------------------------
274// StringTable class implementation
275
276/// Write the length of the string table into Data.
277/// The length of the string table includes uint32 length header.
278void StringTable::update_length() {
279  write_uint32_le(&Data.front(), Data.size());
280}
281
282StringTable::StringTable() {
283  // The string table data begins with the length of the entire string table
284  // including the length header. Allocate space for this header.
285  Data.resize(4);
286}
287
288size_t StringTable::size() const {
289  return Data.size();
290}
291
292/// Add String to the table iff it is not already there.
293/// @returns the index into the string table where the string is now located.
294size_t StringTable::insert(llvm::StringRef String) {
295  map::iterator i = Map.find(String);
296
297  if (i != Map.end())
298    return i->second;
299
300  size_t Offset = Data.size();
301
302  // Insert string data into string table.
303  Data.insert(Data.end(), String.begin(), String.end());
304  Data.push_back('\0');
305
306  // Put a reference to it in the map.
307  Map[String] = Offset;
308
309  // Update the internal length field.
310  update_length();
311
312  return Offset;
313}
314
315//------------------------------------------------------------------------------
316// WinCOFFObjectWriter class implementation
317
318WinCOFFObjectWriter::WinCOFFObjectWriter(raw_ostream &OS, bool is64Bit)
319  : MCObjectWriter(OS, true)
320  , Is64Bit(is64Bit) {
321  memset(&Header, 0, sizeof(Header));
322
323  Is64Bit ? Header.Machine = COFF::IMAGE_FILE_MACHINE_AMD64
324          : Header.Machine = COFF::IMAGE_FILE_MACHINE_I386;
325}
326
327WinCOFFObjectWriter::~WinCOFFObjectWriter() {
328  for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I)
329    delete *I;
330  for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I)
331    delete *I;
332}
333
334COFFSymbol *WinCOFFObjectWriter::createSymbol(llvm::StringRef Name) {
335  return createCOFFEntity<COFFSymbol>(Name, Symbols);
336}
337
338COFFSection *WinCOFFObjectWriter::createSection(llvm::StringRef Name) {
339  return createCOFFEntity<COFFSection>(Name, Sections);
340}
341
342/// A template used to lookup or create a symbol/section, and initialize it if
343/// needed.
344template <typename object_t, typename list_t>
345object_t *WinCOFFObjectWriter::createCOFFEntity(llvm::StringRef Name,
346                                                list_t &List) {
347  object_t *Object = new object_t(Name);
348
349  List.push_back(Object);
350
351  return Object;
352}
353
354/// This function takes a section data object from the assembler
355/// and creates the associated COFF section staging object.
356void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
357  // FIXME: Not sure how to verify this (at least in a debug build).
358  MCSectionCOFF const &Sec =
359    static_cast<MCSectionCOFF const &>(SectionData.getSection());
360
361  COFFSection *coff_section = createSection(Sec.getSectionName());
362  COFFSymbol  *coff_symbol = createSymbol(Sec.getSectionName());
363
364  coff_section->Symbol = coff_symbol;
365  coff_symbol->Section = coff_section;
366  coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
367
368  // In this case the auxiliary symbol is a Section Definition.
369  coff_symbol->Aux.resize(1);
370  memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
371  coff_symbol->Aux[0].AuxType = ATSectionDefinition;
372  coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
373
374  coff_section->Header.Characteristics = Sec.getCharacteristics();
375
376  uint32_t &Characteristics = coff_section->Header.Characteristics;
377  switch (SectionData.getAlignment()) {
378  case 1:    Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES;    break;
379  case 2:    Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES;    break;
380  case 4:    Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES;    break;
381  case 8:    Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES;    break;
382  case 16:   Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES;   break;
383  case 32:   Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES;   break;
384  case 64:   Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES;   break;
385  case 128:  Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES;  break;
386  case 256:  Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES;  break;
387  case 512:  Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES;  break;
388  case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
389  case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
390  case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
391  case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
392  default:
393    llvm_unreachable("unsupported section alignment");
394  }
395
396  // Bind internal COFF section to MC section.
397  coff_section->MCData = &SectionData;
398  SectionMap[&SectionData] = coff_section;
399}
400
401/// This function takes a section data object from the assembler
402/// and creates the associated COFF symbol staging object.
403void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
404                                       MCAssembler &Assembler) {
405  assert(!SymbolData.getSymbol().isVariable()
406    && "Cannot define a symbol that is a variable!");
407  COFFSymbol *coff_symbol = createSymbol(SymbolData.getSymbol().getName());
408
409  coff_symbol->Data.Type         = (SymbolData.getFlags() & 0x0000FFFF) >>  0;
410  coff_symbol->Data.StorageClass = (SymbolData.getFlags() & 0x00FF0000) >> 16;
411
412  // If no storage class was specified in the streamer, define it here.
413  if (coff_symbol->Data.StorageClass == 0) {
414    bool external = SymbolData.isExternal() || (SymbolData.Fragment == NULL);
415
416    coff_symbol->Data.StorageClass =
417      external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_LABEL;
418  }
419
420  if (SymbolData.getFlags() & COFF::SF_WeakReference) {
421    coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
422
423    const MCExpr *Value = SymbolData.getSymbol().getVariableValue();
424
425    // FIXME: This assert message isn't very good.
426    assert(Value->getKind() == MCExpr::SymbolRef &&
427           "Value must be a SymbolRef!");
428
429    const MCSymbolRefExpr *SymbolRef =
430      static_cast<const MCSymbolRefExpr *>(Value);
431
432    const MCSymbolData &OtherSymbolData =
433      Assembler.getSymbolData(SymbolRef->getSymbol());
434
435    // FIXME: This assert message isn't very good.
436    assert(SymbolMap.find(&OtherSymbolData) != SymbolMap.end() &&
437           "OtherSymbolData must be in the symbol map!");
438
439    coff_symbol->Other = SymbolMap[&OtherSymbolData];
440
441    // Setup the Weak External auxiliary symbol.
442    coff_symbol->Aux.resize(1);
443    memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
444    coff_symbol->Aux[0].AuxType = ATWeakExternal;
445    coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
446    coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
447                                        COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
448  }
449
450  if (SymbolData.Fragment != NULL)
451    coff_symbol->Section = SectionMap[SymbolData.Fragment->getParent()];
452
453  // Bind internal COFF symbol to MC symbol.
454  coff_symbol->MCData = &SymbolData;
455  SymbolMap[&SymbolData] = coff_symbol;
456}
457
458/// making a section real involves assigned it a number and putting
459/// name into the string table if needed
460void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
461  if (S.Name.size() > COFF::NameSize) {
462    size_t StringTableEntry = Strings.insert(S.Name.c_str());
463
464    // FIXME: Why is this number 999999? This number is never mentioned in the
465    // spec. I'm assuming this is due to the printed value needing to fit into
466    // the S.Header.Name field. In which case why not 9999999 (7 9's instead of
467    // 6)? The spec does not state if this entry should be null terminated in
468    // this case, and thus this seems to be the best way to do it. I think I
469    // just solved my own FIXME...
470    if (StringTableEntry > 999999)
471      report_fatal_error("COFF string table is greater than 999999 bytes.");
472
473    std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
474  } else
475    std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
476
477  S.Number = Number;
478  S.Symbol->Data.SectionNumber = S.Number;
479  S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
480}
481
482void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
483  if (S.Name.size() > COFF::NameSize) {
484    size_t StringTableEntry = Strings.insert(S.Name.c_str());
485
486    S.set_name_offset(StringTableEntry);
487  } else
488    std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
489  S.Index = Index;
490}
491
492bool WinCOFFObjectWriter::ExportSection(COFFSection const *S) {
493  return !S->MCData->getFragmentList().empty();
494}
495
496bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
497                                       MCAssembler &Asm) {
498  // This doesn't seem to be right. Strings referred to from the .data section
499  // need symbols so they can be linked to code in the .text section right?
500
501  // return Asm.isSymbolLinkerVisible (&SymbolData);
502
503  // For now, all non-variable symbols are exported,
504  // the linker will sort the rest out for us.
505  return !SymbolData.getSymbol().isVariable();
506}
507
508bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
509  return (S->Header.Characteristics
510         & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
511}
512
513//------------------------------------------------------------------------------
514// entity writing methods
515
516void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
517  WriteLE16(Header.Machine);
518  WriteLE16(Header.NumberOfSections);
519  WriteLE32(Header.TimeDateStamp);
520  WriteLE32(Header.PointerToSymbolTable);
521  WriteLE32(Header.NumberOfSymbols);
522  WriteLE16(Header.SizeOfOptionalHeader);
523  WriteLE16(Header.Characteristics);
524}
525
526void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
527  WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
528  WriteLE32(S->Data.Value);
529  WriteLE16(S->Data.SectionNumber);
530  WriteLE16(S->Data.Type);
531  Write8(S->Data.StorageClass);
532  Write8(S->Data.NumberOfAuxSymbols);
533  WriteAuxiliarySymbols(S->Aux);
534}
535
536void WinCOFFObjectWriter::WriteAuxiliarySymbols(
537                                        const COFFSymbol::AuxiliarySymbols &S) {
538  for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
539      i != e; ++i) {
540    switch(i->AuxType) {
541    case ATFunctionDefinition:
542      WriteLE32(i->Aux.FunctionDefinition.TagIndex);
543      WriteLE32(i->Aux.FunctionDefinition.TotalSize);
544      WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
545      WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
546      WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
547      break;
548    case ATbfAndefSymbol:
549      WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
550      WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
551      WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
552      WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
553      WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
554      break;
555    case ATWeakExternal:
556      WriteLE32(i->Aux.WeakExternal.TagIndex);
557      WriteLE32(i->Aux.WeakExternal.Characteristics);
558      WriteZeros(sizeof(i->Aux.WeakExternal.unused));
559      break;
560    case ATFile:
561      WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
562                 sizeof(i->Aux.File.FileName)));
563      break;
564    case ATSectionDefinition:
565      WriteLE32(i->Aux.SectionDefinition.Length);
566      WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
567      WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
568      WriteLE32(i->Aux.SectionDefinition.CheckSum);
569      WriteLE16(i->Aux.SectionDefinition.Number);
570      Write8(i->Aux.SectionDefinition.Selection);
571      WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
572      break;
573    }
574  }
575}
576
577void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
578  WriteBytes(StringRef(S.Name, COFF::NameSize));
579
580  WriteLE32(S.VirtualSize);
581  WriteLE32(S.VirtualAddress);
582  WriteLE32(S.SizeOfRawData);
583  WriteLE32(S.PointerToRawData);
584  WriteLE32(S.PointerToRelocations);
585  WriteLE32(S.PointerToLineNumbers);
586  WriteLE16(S.NumberOfRelocations);
587  WriteLE16(S.NumberOfLineNumbers);
588  WriteLE32(S.Characteristics);
589}
590
591void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
592  WriteLE32(R.VirtualAddress);
593  WriteLE32(R.SymbolTableIndex);
594  WriteLE16(R.Type);
595}
596
597////////////////////////////////////////////////////////////////////////////////
598// MCObjectWriter interface implementations
599
600void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm) {
601  // "Define" each section & symbol. This creates section & symbol
602  // entries in the staging area.
603
604  for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
605    DefineSection(*i);
606
607  for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
608                                          e = Asm.symbol_end(); i != e; i++) {
609    if (ExportSymbol(*i, Asm))
610      DefineSymbol(*i, Asm);
611  }
612}
613
614void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
615                                           const MCAsmLayout &Layout,
616                                           const MCFragment *Fragment,
617                                           const MCFixup &Fixup,
618                                           MCValue Target,
619                                           uint64_t &FixedValue) {
620  assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
621
622  const MCSymbol *A = &Target.getSymA()->getSymbol();
623  MCSymbolData &A_SD = Asm.getSymbolData(*A);
624
625  MCSectionData const *SectionData = Fragment->getParent();
626
627  // Mark this symbol as requiring an entry in the symbol table.
628  assert(SectionMap.find(SectionData) != SectionMap.end() &&
629         "Section must already have been defined in ExecutePostLayoutBinding!");
630  assert(SymbolMap.find(&A_SD) != SymbolMap.end() &&
631         "Symbol must already have been defined in ExecutePostLayoutBinding!");
632
633  COFFSection *coff_section = SectionMap[SectionData];
634  COFFSymbol *coff_symbol = SymbolMap[&A_SD];
635
636  if (Target.getSymB()) {
637    const MCSymbol *B = &Target.getSymB()->getSymbol();
638    MCSymbolData &B_SD = Asm.getSymbolData(*B);
639
640    FixedValue = Layout.getSymbolAddress(&A_SD) - Layout.getSymbolAddress(&B_SD);
641
642    // In the case where we have SymbA and SymB, we just need to store the delta
643    // between the two symbols.  Update FixedValue to account for the delta, and
644    // skip recording the relocation.
645    return;
646  } else {
647    FixedValue = Target.getConstant();
648  }
649
650  COFFRelocation Reloc;
651
652  Reloc.Data.SymbolTableIndex = 0;
653  Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
654
655  // turn relocations for temporary symbols into section relocations
656  if (coff_symbol->MCData->getSymbol().isTemporary()) {
657    Reloc.Symb = coff_symbol->Section->Symbol;
658    FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment);
659  } else
660    Reloc.Symb = coff_symbol;
661
662  ++Reloc.Symb->Relocations;
663
664  Reloc.Data.VirtualAddress += Fixup.getOffset();
665
666  switch (Fixup.getKind()) {
667  case X86::reloc_pcrel_4byte:
668  case X86::reloc_riprel_4byte:
669  case X86::reloc_riprel_4byte_movq_load:
670    Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_REL32
671                              : COFF::IMAGE_REL_I386_REL32;
672    // FIXME: Can anyone explain what this does other than adjust for the size
673    // of the offset?
674    FixedValue += 4;
675    break;
676  case FK_Data_4:
677    Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_ADDR32
678                              : COFF::IMAGE_REL_I386_DIR32;
679    break;
680  case FK_Data_8:
681    if (Is64Bit)
682      Reloc.Data.Type = COFF::IMAGE_REL_AMD64_ADDR64;
683    else
684      llvm_unreachable("unsupported relocation type");
685    break;
686  default:
687    llvm_unreachable("unsupported relocation type");
688  }
689
690  coff_section->Relocations.push_back(Reloc);
691}
692
693void WinCOFFObjectWriter::WriteObject(const MCAssembler &Asm,
694                                      const MCAsmLayout &Layout) {
695  // Assign symbol and section indexes and offsets.
696  Header.NumberOfSections = 0;
697
698  for (sections::iterator i = Sections.begin(),
699                          e = Sections.end(); i != e; i++) {
700    if (Layout.getSectionSize((*i)->MCData) > 0) {
701      MakeSectionReal(**i, ++Header.NumberOfSections);
702    } else {
703      (*i)->Number = -1;
704    }
705  }
706
707  Header.NumberOfSymbols = 0;
708
709  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
710    COFFSymbol *coff_symbol = *i;
711    MCSymbolData const *SymbolData = coff_symbol->MCData;
712
713    // Update section number & offset for symbols that have them.
714    if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
715      assert(coff_symbol->Section != NULL);
716
717      coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
718      coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
719                              + SymbolData->Offset;
720    }
721
722    if (coff_symbol->should_keep()) {
723      MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
724
725      // Update auxiliary symbol info.
726      coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
727      Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
728    } else
729      coff_symbol->Index = -1;
730  }
731
732  // Fixup weak external references.
733  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
734    COFFSymbol *coff_symbol = *i;
735    if (coff_symbol->Other != NULL) {
736      assert(coff_symbol->Index != -1);
737      assert(coff_symbol->Aux.size() == 1 &&
738             "Symbol must contain one aux symbol!");
739      assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
740             "Symbol's aux symbol must be a Weak External!");
741      coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
742    }
743  }
744
745  // Assign file offsets to COFF object file structures.
746
747  unsigned offset = 0;
748
749  offset += COFF::HeaderSize;
750  offset += COFF::SectionSize * Header.NumberOfSections;
751
752  for (MCAssembler::const_iterator i = Asm.begin(),
753                                   e = Asm.end();
754                                   i != e; i++) {
755    COFFSection *Sec = SectionMap[i];
756
757    if (Sec->Number == -1)
758      continue;
759
760    Sec->Header.SizeOfRawData = Layout.getSectionFileSize(i);
761
762    if (IsPhysicalSection(Sec)) {
763      Sec->Header.PointerToRawData = offset;
764
765      offset += Sec->Header.SizeOfRawData;
766    }
767
768    if (Sec->Relocations.size() > 0) {
769      Sec->Header.NumberOfRelocations = Sec->Relocations.size();
770      Sec->Header.PointerToRelocations = offset;
771
772      offset += COFF::RelocationSize * Sec->Relocations.size();
773
774      for (relocations::iterator cr = Sec->Relocations.begin(),
775                                 er = Sec->Relocations.end();
776                                 cr != er; ++cr) {
777        assert((*cr).Symb->Index != -1);
778        (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
779      }
780    }
781
782    assert(Sec->Symbol->Aux.size() == 1
783      && "Section's symbol must have one aux!");
784    AuxSymbol &Aux = Sec->Symbol->Aux[0];
785    assert(Aux.AuxType == ATSectionDefinition &&
786           "Section's symbol's aux symbol must be a Section Definition!");
787    Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
788    Aux.Aux.SectionDefinition.NumberOfRelocations =
789                                                Sec->Header.NumberOfRelocations;
790    Aux.Aux.SectionDefinition.NumberOfLinenumbers =
791                                                Sec->Header.NumberOfLineNumbers;
792  }
793
794  Header.PointerToSymbolTable = offset;
795
796  Header.TimeDateStamp = sys::TimeValue::now().toEpochTime();
797
798  // Write it all to disk...
799  WriteFileHeader(Header);
800
801  {
802    sections::iterator i, ie;
803    MCAssembler::const_iterator j, je;
804
805    for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
806      if ((*i)->Number != -1)
807        WriteSectionHeader((*i)->Header);
808
809    for (i = Sections.begin(), ie = Sections.end(),
810         j = Asm.begin(), je = Asm.end();
811         (i != ie) && (j != je); ++i, ++j) {
812
813      if ((*i)->Number == -1)
814        continue;
815
816      if ((*i)->Header.PointerToRawData != 0) {
817        assert(OS.tell() == (*i)->Header.PointerToRawData &&
818               "Section::PointerToRawData is insane!");
819
820        Asm.WriteSectionData(j, Layout, this);
821      }
822
823      if ((*i)->Relocations.size() > 0) {
824        assert(OS.tell() == (*i)->Header.PointerToRelocations &&
825               "Section::PointerToRelocations is insane!");
826
827        for (relocations::const_iterator k = (*i)->Relocations.begin(),
828                                               ke = (*i)->Relocations.end();
829                                               k != ke; k++) {
830          WriteRelocation(k->Data);
831        }
832      } else
833        assert((*i)->Header.PointerToRelocations == 0 &&
834               "Section::PointerToRelocations is insane!");
835    }
836  }
837
838  assert(OS.tell() == Header.PointerToSymbolTable &&
839         "Header::PointerToSymbolTable is insane!");
840
841  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
842    if ((*i)->Index != -1)
843      WriteSymbol(*i);
844
845  OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
846}
847
848//------------------------------------------------------------------------------
849// WinCOFFObjectWriter factory function
850
851namespace llvm {
852  MCObjectWriter *createWinCOFFObjectWriter(raw_ostream &OS, bool is64Bit) {
853    return new WinCOFFObjectWriter(OS, is64Bit);
854  }
855}
856