WinCOFFObjectWriter.cpp revision d47f4a9c982d264e46a6a2fe0f357288768bb5b9 
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  virtual bool IsFixupFullyResolved(const MCAssembler &Asm,
185                                    const MCValue Target,
186                                    bool IsPCRel,
187                                    const MCFragment *DF) const;
188
189  void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
190};
191}
192
193static inline void write_uint32_le(void *Data, uint32_t const &Value) {
194  uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
195  Ptr[0] = (Value & 0x000000FF) >>  0;
196  Ptr[1] = (Value & 0x0000FF00) >>  8;
197  Ptr[2] = (Value & 0x00FF0000) >> 16;
198  Ptr[3] = (Value & 0xFF000000) >> 24;
199}
200
201static inline void write_uint16_le(void *Data, uint16_t const &Value) {
202  uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
203  Ptr[0] = (Value & 0x00FF) >> 0;
204  Ptr[1] = (Value & 0xFF00) >> 8;
205}
206
207static inline void write_uint8_le(void *Data, uint8_t const &Value) {
208  uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
209  Ptr[0] = (Value & 0xFF) >> 0;
210}
211
212//------------------------------------------------------------------------------
213// Symbol class implementation
214
215COFFSymbol::COFFSymbol(llvm::StringRef name)
216  : Name(name.begin(), name.end())
217  , Other(NULL)
218  , Section(NULL)
219  , Relocations(0)
220  , MCData(NULL) {
221  memset(&Data, 0, sizeof(Data));
222}
223
224size_t COFFSymbol::size() const {
225  return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
226}
227
228// In the case that the name does not fit within 8 bytes, the offset
229// into the string table is stored in the last 4 bytes instead, leaving
230// the first 4 bytes as 0.
231void COFFSymbol::set_name_offset(uint32_t Offset) {
232  write_uint32_le(Data.Name + 0, 0);
233  write_uint32_le(Data.Name + 4, Offset);
234}
235
236/// logic to decide if the symbol should be reported in the symbol table
237bool COFFSymbol::should_keep() const {
238  // no section means its external, keep it
239  if (Section == NULL)
240    return true;
241
242  // if it has relocations pointing at it, keep it
243  if (Relocations > 0)   {
244    assert(Section->Number != -1 && "Sections with relocations must be real!");
245    return true;
246  }
247
248  // if the section its in is being droped, drop it
249  if (Section->Number == -1)
250      return false;
251
252  // if it is the section symbol, keep it
253  if (Section->Symbol == this)
254    return true;
255
256  // if its temporary, drop it
257  if (MCData && MCData->getSymbol().isTemporary())
258      return false;
259
260  // otherwise, keep it
261  return true;
262}
263
264//------------------------------------------------------------------------------
265// Section class implementation
266
267COFFSection::COFFSection(llvm::StringRef name)
268  : Name(name)
269  , MCData(NULL)
270  , Symbol(NULL) {
271  memset(&Header, 0, sizeof(Header));
272}
273
274size_t COFFSection::size() {
275  return COFF::SectionSize;
276}
277
278//------------------------------------------------------------------------------
279// StringTable class implementation
280
281/// Write the length of the string table into Data.
282/// The length of the string table includes uint32 length header.
283void StringTable::update_length() {
284  write_uint32_le(&Data.front(), Data.size());
285}
286
287StringTable::StringTable() {
288  // The string table data begins with the length of the entire string table
289  // including the length header. Allocate space for this header.
290  Data.resize(4);
291}
292
293size_t StringTable::size() const {
294  return Data.size();
295}
296
297/// Add String to the table iff it is not already there.
298/// @returns the index into the string table where the string is now located.
299size_t StringTable::insert(llvm::StringRef String) {
300  map::iterator i = Map.find(String);
301
302  if (i != Map.end())
303    return i->second;
304
305  size_t Offset = Data.size();
306
307  // Insert string data into string table.
308  Data.insert(Data.end(), String.begin(), String.end());
309  Data.push_back('\0');
310
311  // Put a reference to it in the map.
312  Map[String] = Offset;
313
314  // Update the internal length field.
315  update_length();
316
317  return Offset;
318}
319
320//------------------------------------------------------------------------------
321// WinCOFFObjectWriter class implementation
322
323WinCOFFObjectWriter::WinCOFFObjectWriter(raw_ostream &OS, bool is64Bit)
324  : MCObjectWriter(OS, true)
325  , Is64Bit(is64Bit) {
326  memset(&Header, 0, sizeof(Header));
327
328  Is64Bit ? Header.Machine = COFF::IMAGE_FILE_MACHINE_AMD64
329          : Header.Machine = COFF::IMAGE_FILE_MACHINE_I386;
330}
331
332WinCOFFObjectWriter::~WinCOFFObjectWriter() {
333  for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I)
334    delete *I;
335  for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I)
336    delete *I;
337}
338
339COFFSymbol *WinCOFFObjectWriter::createSymbol(llvm::StringRef Name) {
340  return createCOFFEntity<COFFSymbol>(Name, Symbols);
341}
342
343COFFSection *WinCOFFObjectWriter::createSection(llvm::StringRef Name) {
344  return createCOFFEntity<COFFSection>(Name, Sections);
345}
346
347/// A template used to lookup or create a symbol/section, and initialize it if
348/// needed.
349template <typename object_t, typename list_t>
350object_t *WinCOFFObjectWriter::createCOFFEntity(llvm::StringRef Name,
351                                                list_t &List) {
352  object_t *Object = new object_t(Name);
353
354  List.push_back(Object);
355
356  return Object;
357}
358
359/// This function takes a section data object from the assembler
360/// and creates the associated COFF section staging object.
361void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
362  assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
363    && "Got non COFF section in the COFF backend!");
364  // FIXME: Not sure how to verify this (at least in a debug build).
365  MCSectionCOFF const &Sec =
366    static_cast<MCSectionCOFF const &>(SectionData.getSection());
367
368  COFFSection *coff_section = createSection(Sec.getSectionName());
369  COFFSymbol  *coff_symbol = createSymbol(Sec.getSectionName());
370
371  coff_section->Symbol = coff_symbol;
372  coff_symbol->Section = coff_section;
373  coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
374
375  // In this case the auxiliary symbol is a Section Definition.
376  coff_symbol->Aux.resize(1);
377  memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
378  coff_symbol->Aux[0].AuxType = ATSectionDefinition;
379  coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
380
381  coff_section->Header.Characteristics = Sec.getCharacteristics();
382
383  uint32_t &Characteristics = coff_section->Header.Characteristics;
384  switch (SectionData.getAlignment()) {
385  case 1:    Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES;    break;
386  case 2:    Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES;    break;
387  case 4:    Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES;    break;
388  case 8:    Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES;    break;
389  case 16:   Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES;   break;
390  case 32:   Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES;   break;
391  case 64:   Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES;   break;
392  case 128:  Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES;  break;
393  case 256:  Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES;  break;
394  case 512:  Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES;  break;
395  case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
396  case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
397  case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
398  case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
399  default:
400    llvm_unreachable("unsupported section alignment");
401  }
402
403  // Bind internal COFF section to MC section.
404  coff_section->MCData = &SectionData;
405  SectionMap[&SectionData] = coff_section;
406}
407
408/// This function takes a section data object from the assembler
409/// and creates the associated COFF symbol staging object.
410void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
411                                       MCAssembler &Assembler) {
412  assert(!SymbolData.getSymbol().isVariable()
413    && "Cannot define a symbol that is a variable!");
414  COFFSymbol *coff_symbol = createSymbol(SymbolData.getSymbol().getName());
415
416  coff_symbol->Data.Type         = (SymbolData.getFlags() & 0x0000FFFF) >>  0;
417  coff_symbol->Data.StorageClass = (SymbolData.getFlags() & 0x00FF0000) >> 16;
418
419  // If no storage class was specified in the streamer, define it here.
420  if (coff_symbol->Data.StorageClass == 0) {
421    bool external = SymbolData.isExternal() || (SymbolData.Fragment == NULL);
422
423    coff_symbol->Data.StorageClass =
424      external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC;
425  }
426
427  if (SymbolData.getFlags() & COFF::SF_WeakReference) {
428    coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
429
430    const MCExpr *Value = SymbolData.getSymbol().getVariableValue();
431
432    // FIXME: This assert message isn't very good.
433    assert(Value->getKind() == MCExpr::SymbolRef &&
434           "Value must be a SymbolRef!");
435
436    const MCSymbolRefExpr *SymbolRef =
437      static_cast<const MCSymbolRefExpr *>(Value);
438
439    const MCSymbolData &OtherSymbolData =
440      Assembler.getSymbolData(SymbolRef->getSymbol());
441
442    // FIXME: This assert message isn't very good.
443    assert(SymbolMap.find(&OtherSymbolData) != SymbolMap.end() &&
444           "OtherSymbolData must be in the symbol map!");
445
446    coff_symbol->Other = SymbolMap[&OtherSymbolData];
447
448    // Setup the Weak External auxiliary symbol.
449    coff_symbol->Aux.resize(1);
450    memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
451    coff_symbol->Aux[0].AuxType = ATWeakExternal;
452    coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
453    coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
454                                        COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
455  }
456
457  if (SymbolData.Fragment != NULL)
458    coff_symbol->Section = SectionMap[SymbolData.Fragment->getParent()];
459
460  // Bind internal COFF symbol to MC symbol.
461  coff_symbol->MCData = &SymbolData;
462  SymbolMap[&SymbolData] = coff_symbol;
463}
464
465/// making a section real involves assigned it a number and putting
466/// name into the string table if needed
467void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
468  if (S.Name.size() > COFF::NameSize) {
469    size_t StringTableEntry = Strings.insert(S.Name.c_str());
470
471    // FIXME: Why is this number 999999? This number is never mentioned in the
472    // spec. I'm assuming this is due to the printed value needing to fit into
473    // the S.Header.Name field. In which case why not 9999999 (7 9's instead of
474    // 6)? The spec does not state if this entry should be null terminated in
475    // this case, and thus this seems to be the best way to do it. I think I
476    // just solved my own FIXME...
477    if (StringTableEntry > 999999)
478      report_fatal_error("COFF string table is greater than 999999 bytes.");
479
480    std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
481  } else
482    std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
483
484  S.Number = Number;
485  S.Symbol->Data.SectionNumber = S.Number;
486  S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
487}
488
489void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
490  if (S.Name.size() > COFF::NameSize) {
491    size_t StringTableEntry = Strings.insert(S.Name.c_str());
492
493    S.set_name_offset(StringTableEntry);
494  } else
495    std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
496  S.Index = Index;
497}
498
499bool WinCOFFObjectWriter::ExportSection(COFFSection const *S) {
500  return !S->MCData->getFragmentList().empty();
501}
502
503bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
504                                       MCAssembler &Asm) {
505  // This doesn't seem to be right. Strings referred to from the .data section
506  // need symbols so they can be linked to code in the .text section right?
507
508  // return Asm.isSymbolLinkerVisible (&SymbolData);
509
510  // For now, all non-variable symbols are exported,
511  // the linker will sort the rest out for us.
512  return !SymbolData.getSymbol().isVariable();
513}
514
515bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
516  return (S->Header.Characteristics
517         & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
518}
519
520//------------------------------------------------------------------------------
521// entity writing methods
522
523void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
524  WriteLE16(Header.Machine);
525  WriteLE16(Header.NumberOfSections);
526  WriteLE32(Header.TimeDateStamp);
527  WriteLE32(Header.PointerToSymbolTable);
528  WriteLE32(Header.NumberOfSymbols);
529  WriteLE16(Header.SizeOfOptionalHeader);
530  WriteLE16(Header.Characteristics);
531}
532
533void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
534  WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
535  WriteLE32(S->Data.Value);
536  WriteLE16(S->Data.SectionNumber);
537  WriteLE16(S->Data.Type);
538  Write8(S->Data.StorageClass);
539  Write8(S->Data.NumberOfAuxSymbols);
540  WriteAuxiliarySymbols(S->Aux);
541}
542
543void WinCOFFObjectWriter::WriteAuxiliarySymbols(
544                                        const COFFSymbol::AuxiliarySymbols &S) {
545  for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
546      i != e; ++i) {
547    switch(i->AuxType) {
548    case ATFunctionDefinition:
549      WriteLE32(i->Aux.FunctionDefinition.TagIndex);
550      WriteLE32(i->Aux.FunctionDefinition.TotalSize);
551      WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
552      WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
553      WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
554      break;
555    case ATbfAndefSymbol:
556      WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
557      WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
558      WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
559      WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
560      WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
561      break;
562    case ATWeakExternal:
563      WriteLE32(i->Aux.WeakExternal.TagIndex);
564      WriteLE32(i->Aux.WeakExternal.Characteristics);
565      WriteZeros(sizeof(i->Aux.WeakExternal.unused));
566      break;
567    case ATFile:
568      WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
569                 sizeof(i->Aux.File.FileName)));
570      break;
571    case ATSectionDefinition:
572      WriteLE32(i->Aux.SectionDefinition.Length);
573      WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
574      WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
575      WriteLE32(i->Aux.SectionDefinition.CheckSum);
576      WriteLE16(i->Aux.SectionDefinition.Number);
577      Write8(i->Aux.SectionDefinition.Selection);
578      WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
579      break;
580    }
581  }
582}
583
584void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
585  WriteBytes(StringRef(S.Name, COFF::NameSize));
586
587  WriteLE32(S.VirtualSize);
588  WriteLE32(S.VirtualAddress);
589  WriteLE32(S.SizeOfRawData);
590  WriteLE32(S.PointerToRawData);
591  WriteLE32(S.PointerToRelocations);
592  WriteLE32(S.PointerToLineNumbers);
593  WriteLE16(S.NumberOfRelocations);
594  WriteLE16(S.NumberOfLineNumbers);
595  WriteLE32(S.Characteristics);
596}
597
598void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
599  WriteLE32(R.VirtualAddress);
600  WriteLE32(R.SymbolTableIndex);
601  WriteLE16(R.Type);
602}
603
604////////////////////////////////////////////////////////////////////////////////
605// MCObjectWriter interface implementations
606
607void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm) {
608  // "Define" each section & symbol. This creates section & symbol
609  // entries in the staging area.
610
611  for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
612    DefineSection(*i);
613
614  for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
615                                          e = Asm.symbol_end(); i != e; i++) {
616    if (ExportSymbol(*i, Asm))
617      DefineSymbol(*i, Asm);
618  }
619}
620
621void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
622                                           const MCAsmLayout &Layout,
623                                           const MCFragment *Fragment,
624                                           const MCFixup &Fixup,
625                                           MCValue Target,
626                                           uint64_t &FixedValue) {
627  assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
628
629  const MCSymbol *A = &Target.getSymA()->getSymbol();
630  MCSymbolData &A_SD = Asm.getSymbolData(*A);
631
632  MCSectionData const *SectionData = Fragment->getParent();
633
634  // Mark this symbol as requiring an entry in the symbol table.
635  assert(SectionMap.find(SectionData) != SectionMap.end() &&
636         "Section must already have been defined in ExecutePostLayoutBinding!");
637  assert(SymbolMap.find(&A_SD) != SymbolMap.end() &&
638         "Symbol must already have been defined in ExecutePostLayoutBinding!");
639
640  COFFSection *coff_section = SectionMap[SectionData];
641  COFFSymbol *coff_symbol = SymbolMap[&A_SD];
642
643  if (Target.getSymB()) {
644    if (&Target.getSymA()->getSymbol().getSection()
645     != &Target.getSymB()->getSymbol().getSection()) {
646      llvm_unreachable("Symbol relative relocations are only allowed between "
647                       "symbols in the same section");
648    }
649    const MCSymbol *B = &Target.getSymB()->getSymbol();
650    MCSymbolData &B_SD = Asm.getSymbolData(*B);
651
652    FixedValue = Layout.getSymbolAddress(&A_SD) - Layout.getSymbolAddress(&B_SD);
653
654    // In the case where we have SymbA and SymB, we just need to store the delta
655    // between the two symbols.  Update FixedValue to account for the delta, and
656    // skip recording the relocation.
657    return;
658  } else {
659    FixedValue = Target.getConstant();
660  }
661
662  COFFRelocation Reloc;
663
664  Reloc.Data.SymbolTableIndex = 0;
665  Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
666
667  // Turn relocations for temporary symbols into section relocations.
668  if (coff_symbol->MCData->getSymbol().isTemporary()) {
669    Reloc.Symb = coff_symbol->Section->Symbol;
670    FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
671                + coff_symbol->MCData->getOffset();
672  } else
673    Reloc.Symb = coff_symbol;
674
675  ++Reloc.Symb->Relocations;
676
677  Reloc.Data.VirtualAddress += Fixup.getOffset();
678
679  switch (Fixup.getKind()) {
680  case X86::reloc_pcrel_4byte:
681  case X86::reloc_riprel_4byte:
682  case X86::reloc_riprel_4byte_movq_load:
683    Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_REL32
684                              : COFF::IMAGE_REL_I386_REL32;
685    // FIXME: Can anyone explain what this does other than adjust for the size
686    // of the offset?
687    FixedValue += 4;
688    break;
689  case FK_Data_4:
690  case X86::reloc_signed_4byte:
691    Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_ADDR32
692                              : COFF::IMAGE_REL_I386_DIR32;
693    break;
694  case FK_Data_8:
695    if (Is64Bit)
696      Reloc.Data.Type = COFF::IMAGE_REL_AMD64_ADDR64;
697    else
698      llvm_unreachable("unsupported relocation type");
699    break;
700  default:
701    llvm_unreachable("unsupported relocation type");
702  }
703
704  coff_section->Relocations.push_back(Reloc);
705}
706
707bool WinCOFFObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
708                                               const MCValue Target,
709                                               bool IsPCRel,
710                                               const MCFragment *DF) const {
711  // If this is a PCrel relocation, find the section this fixup value is
712  // relative to.
713  const MCSection *BaseSection = 0;
714  if (IsPCRel) {
715    BaseSection = &DF->getParent()->getSection();
716    assert(BaseSection);
717  }
718
719  const MCSection *SectionA = 0;
720  const MCSymbol *SymbolA = 0;
721  if (const MCSymbolRefExpr *A = Target.getSymA()) {
722    SymbolA = &A->getSymbol();
723    SectionA = &SymbolA->getSection();
724  }
725
726  const MCSection *SectionB = 0;
727  if (const MCSymbolRefExpr *B = Target.getSymB()) {
728    SectionB = &B->getSymbol().getSection();
729  }
730
731  if (!BaseSection)
732    return SectionA == SectionB;
733
734  return !SectionB && BaseSection == SectionA;
735}
736
737void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
738                                      const MCAsmLayout &Layout) {
739  // Assign symbol and section indexes and offsets.
740  Header.NumberOfSections = 0;
741
742  for (sections::iterator i = Sections.begin(),
743                          e = Sections.end(); i != e; i++) {
744    if (Layout.getSectionSize((*i)->MCData) > 0) {
745      MakeSectionReal(**i, ++Header.NumberOfSections);
746    } else {
747      (*i)->Number = -1;
748    }
749  }
750
751  Header.NumberOfSymbols = 0;
752
753  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
754    COFFSymbol *coff_symbol = *i;
755    MCSymbolData const *SymbolData = coff_symbol->MCData;
756
757    // Update section number & offset for symbols that have them.
758    if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
759      assert(coff_symbol->Section != NULL);
760
761      coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
762      coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
763                              + SymbolData->Offset;
764    }
765
766    if (coff_symbol->should_keep()) {
767      MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
768
769      // Update auxiliary symbol info.
770      coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
771      Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
772    } else
773      coff_symbol->Index = -1;
774  }
775
776  // Fixup weak external references.
777  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
778    COFFSymbol *coff_symbol = *i;
779    if (coff_symbol->Other != NULL) {
780      assert(coff_symbol->Index != -1);
781      assert(coff_symbol->Aux.size() == 1 &&
782             "Symbol must contain one aux symbol!");
783      assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
784             "Symbol's aux symbol must be a Weak External!");
785      coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
786    }
787  }
788
789  // Assign file offsets to COFF object file structures.
790
791  unsigned offset = 0;
792
793  offset += COFF::HeaderSize;
794  offset += COFF::SectionSize * Header.NumberOfSections;
795
796  for (MCAssembler::const_iterator i = Asm.begin(),
797                                   e = Asm.end();
798                                   i != e; i++) {
799    COFFSection *Sec = SectionMap[i];
800
801    if (Sec->Number == -1)
802      continue;
803
804    Sec->Header.SizeOfRawData = Layout.getSectionFileSize(i);
805
806    if (IsPhysicalSection(Sec)) {
807      Sec->Header.PointerToRawData = offset;
808
809      offset += Sec->Header.SizeOfRawData;
810    }
811
812    if (Sec->Relocations.size() > 0) {
813      Sec->Header.NumberOfRelocations = Sec->Relocations.size();
814      Sec->Header.PointerToRelocations = offset;
815
816      offset += COFF::RelocationSize * Sec->Relocations.size();
817
818      for (relocations::iterator cr = Sec->Relocations.begin(),
819                                 er = Sec->Relocations.end();
820                                 cr != er; ++cr) {
821        assert((*cr).Symb->Index != -1);
822        (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
823      }
824    }
825
826    assert(Sec->Symbol->Aux.size() == 1
827      && "Section's symbol must have one aux!");
828    AuxSymbol &Aux = Sec->Symbol->Aux[0];
829    assert(Aux.AuxType == ATSectionDefinition &&
830           "Section's symbol's aux symbol must be a Section Definition!");
831    Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
832    Aux.Aux.SectionDefinition.NumberOfRelocations =
833                                                Sec->Header.NumberOfRelocations;
834    Aux.Aux.SectionDefinition.NumberOfLinenumbers =
835                                                Sec->Header.NumberOfLineNumbers;
836  }
837
838  Header.PointerToSymbolTable = offset;
839
840  Header.TimeDateStamp = sys::TimeValue::now().toEpochTime();
841
842  // Write it all to disk...
843  WriteFileHeader(Header);
844
845  {
846    sections::iterator i, ie;
847    MCAssembler::const_iterator j, je;
848
849    for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
850      if ((*i)->Number != -1)
851        WriteSectionHeader((*i)->Header);
852
853    for (i = Sections.begin(), ie = Sections.end(),
854         j = Asm.begin(), je = Asm.end();
855         (i != ie) && (j != je); ++i, ++j) {
856
857      if ((*i)->Number == -1)
858        continue;
859
860      if ((*i)->Header.PointerToRawData != 0) {
861        assert(OS.tell() == (*i)->Header.PointerToRawData &&
862               "Section::PointerToRawData is insane!");
863
864        Asm.WriteSectionData(j, Layout, this);
865      }
866
867      if ((*i)->Relocations.size() > 0) {
868        assert(OS.tell() == (*i)->Header.PointerToRelocations &&
869               "Section::PointerToRelocations is insane!");
870
871        for (relocations::const_iterator k = (*i)->Relocations.begin(),
872                                               ke = (*i)->Relocations.end();
873                                               k != ke; k++) {
874          WriteRelocation(k->Data);
875        }
876      } else
877        assert((*i)->Header.PointerToRelocations == 0 &&
878               "Section::PointerToRelocations is insane!");
879    }
880  }
881
882  assert(OS.tell() == Header.PointerToSymbolTable &&
883         "Header::PointerToSymbolTable is insane!");
884
885  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
886    if ((*i)->Index != -1)
887      WriteSymbol(*i);
888
889  OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
890}
891
892//------------------------------------------------------------------------------
893// WinCOFFObjectWriter factory function
894
895namespace llvm {
896  MCObjectWriter *createWinCOFFObjectWriter(raw_ostream &OS, bool is64Bit) {
897    return new WinCOFFObjectWriter(OS, is64Bit);
898  }
899}
900