1 //===-- llvm/MC/WinCOFFObjectWriter.cpp -------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains an implementation of a Win32 COFF object file writer.
12 //===----------------------------------------------------------------------===//
14 #define DEBUG_TYPE "WinCOFFObjectWriter"
16 #include "llvm/MC/MCWinCOFFObjectWriter.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/OwningPtr.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/ADT/Twine.h"
22 #include "llvm/MC/MCAsmLayout.h"
23 #include "llvm/MC/MCAssembler.h"
24 #include "llvm/MC/MCContext.h"
25 #include "llvm/MC/MCExpr.h"
26 #include "llvm/MC/MCObjectWriter.h"
27 #include "llvm/MC/MCSection.h"
28 #include "llvm/MC/MCSectionCOFF.h"
29 #include "llvm/MC/MCSymbol.h"
30 #include "llvm/MC/MCValue.h"
31 #include "llvm/Support/COFF.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/TimeValue.h"
40 typedef SmallString<COFF::NameSize> name;
51 AuxiliaryType AuxType;
62 typedef SmallVector<AuxSymbol, 1> AuxiliarySymbols;
71 MCSymbolData const *MCData;
73 COFFSymbol(StringRef name);
75 void set_name_offset(uint32_t Offset);
77 bool should_keep() const;
80 // This class contains staging data for a COFF relocation entry.
81 struct COFFRelocation {
82 COFF::relocation Data;
85 COFFRelocation() : Symb(NULL) {}
86 static size_t size() { return COFF::RelocationSize; }
89 typedef std::vector<COFFRelocation> relocations;
97 MCSectionData const *MCData;
99 relocations Relocations;
101 COFFSection(StringRef name);
102 static size_t size();
105 // This class holds the COFF string table.
107 typedef StringMap<size_t> map;
110 void update_length();
112 std::vector<char> Data;
116 size_t insert(StringRef String);
119 class WinCOFFObjectWriter : public MCObjectWriter {
122 typedef std::vector<COFFSymbol*> symbols;
123 typedef std::vector<COFFSection*> sections;
125 typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map;
126 typedef DenseMap<MCSection const *, COFFSection *> section_map;
128 llvm::OwningPtr<MCWinCOFFObjectTargetWriter> TargetObjectWriter;
130 // Root level file contents.
136 // Maps used during object file creation.
137 section_map SectionMap;
138 symbol_map SymbolMap;
140 WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, raw_ostream &OS);
141 virtual ~WinCOFFObjectWriter();
143 COFFSymbol *createSymbol(StringRef Name);
144 COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol);
145 COFFSection *createSection(StringRef Name);
147 template <typename object_t, typename list_t>
148 object_t *createCOFFEntity(StringRef Name, list_t &List);
150 void DefineSection(MCSectionData const &SectionData);
151 void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler,
152 const MCAsmLayout &Layout);
154 void MakeSymbolReal(COFFSymbol &S, size_t Index);
155 void MakeSectionReal(COFFSection &S, size_t Number);
157 bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm);
159 bool IsPhysicalSection(COFFSection *S);
161 // Entity writing methods.
163 void WriteFileHeader(const COFF::header &Header);
164 void WriteSymbol(const COFFSymbol *S);
165 void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
166 void WriteSectionHeader(const COFF::section &S);
167 void WriteRelocation(const COFF::relocation &R);
169 // MCObjectWriter interface implementation.
171 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout);
173 void RecordRelocation(const MCAssembler &Asm,
174 const MCAsmLayout &Layout,
175 const MCFragment *Fragment,
176 const MCFixup &Fixup,
178 uint64_t &FixedValue);
180 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
184 static inline void write_uint32_le(void *Data, uint32_t const &Value) {
185 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
186 Ptr[0] = (Value & 0x000000FF) >> 0;
187 Ptr[1] = (Value & 0x0000FF00) >> 8;
188 Ptr[2] = (Value & 0x00FF0000) >> 16;
189 Ptr[3] = (Value & 0xFF000000) >> 24;
192 //------------------------------------------------------------------------------
193 // Symbol class implementation
195 COFFSymbol::COFFSymbol(StringRef name)
196 : Name(name.begin(), name.end())
201 memset(&Data, 0, sizeof(Data));
204 size_t COFFSymbol::size() const {
205 return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
208 // In the case that the name does not fit within 8 bytes, the offset
209 // into the string table is stored in the last 4 bytes instead, leaving
210 // the first 4 bytes as 0.
211 void COFFSymbol::set_name_offset(uint32_t Offset) {
212 write_uint32_le(Data.Name + 0, 0);
213 write_uint32_le(Data.Name + 4, Offset);
216 /// logic to decide if the symbol should be reported in the symbol table
217 bool COFFSymbol::should_keep() const {
218 // no section means its external, keep it
222 // if it has relocations pointing at it, keep it
223 if (Relocations > 0) {
224 assert(Section->Number != -1 && "Sections with relocations must be real!");
228 // if the section its in is being droped, drop it
229 if (Section->Number == -1)
232 // if it is the section symbol, keep it
233 if (Section->Symbol == this)
236 // if its temporary, drop it
237 if (MCData && MCData->getSymbol().isTemporary())
240 // otherwise, keep it
244 //------------------------------------------------------------------------------
245 // Section class implementation
247 COFFSection::COFFSection(StringRef name)
251 memset(&Header, 0, sizeof(Header));
254 size_t COFFSection::size() {
255 return COFF::SectionSize;
258 //------------------------------------------------------------------------------
259 // StringTable class implementation
261 /// Write the length of the string table into Data.
262 /// The length of the string table includes uint32 length header.
263 void StringTable::update_length() {
264 write_uint32_le(&Data.front(), Data.size());
267 StringTable::StringTable() {
268 // The string table data begins with the length of the entire string table
269 // including the length header. Allocate space for this header.
274 size_t StringTable::size() const {
278 /// Add String to the table iff it is not already there.
279 /// @returns the index into the string table where the string is now located.
280 size_t StringTable::insert(StringRef String) {
281 map::iterator i = Map.find(String);
286 size_t Offset = Data.size();
288 // Insert string data into string table.
289 Data.insert(Data.end(), String.begin(), String.end());
290 Data.push_back('\0');
292 // Put a reference to it in the map.
293 Map[String] = Offset;
295 // Update the internal length field.
301 //------------------------------------------------------------------------------
302 // WinCOFFObjectWriter class implementation
304 WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
306 : MCObjectWriter(OS, true)
307 , TargetObjectWriter(MOTW) {
308 memset(&Header, 0, sizeof(Header));
310 Header.Machine = TargetObjectWriter->getMachine();
313 WinCOFFObjectWriter::~WinCOFFObjectWriter() {
314 for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I)
316 for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I)
320 COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
321 return createCOFFEntity<COFFSymbol>(Name, Symbols);
324 COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
325 symbol_map::iterator i = SymbolMap.find(Symbol);
326 if (i != SymbolMap.end())
328 COFFSymbol *RetSymbol
329 = createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
330 SymbolMap[Symbol] = RetSymbol;
334 COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) {
335 return createCOFFEntity<COFFSection>(Name, Sections);
338 /// A template used to lookup or create a symbol/section, and initialize it if
340 template <typename object_t, typename list_t>
341 object_t *WinCOFFObjectWriter::createCOFFEntity(StringRef Name,
343 object_t *Object = new object_t(Name);
345 List.push_back(Object);
350 /// This function takes a section data object from the assembler
351 /// and creates the associated COFF section staging object.
352 void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
353 assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
354 && "Got non-COFF section in the COFF backend!");
355 // FIXME: Not sure how to verify this (at least in a debug build).
356 MCSectionCOFF const &Sec =
357 static_cast<MCSectionCOFF const &>(SectionData.getSection());
359 COFFSection *coff_section = createSection(Sec.getSectionName());
360 COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
362 coff_section->Symbol = coff_symbol;
363 coff_symbol->Section = coff_section;
364 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
366 // In this case the auxiliary symbol is a Section Definition.
367 coff_symbol->Aux.resize(1);
368 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
369 coff_symbol->Aux[0].AuxType = ATSectionDefinition;
370 coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
372 coff_section->Header.Characteristics = Sec.getCharacteristics();
374 uint32_t &Characteristics = coff_section->Header.Characteristics;
375 switch (SectionData.getAlignment()) {
376 case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break;
377 case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break;
378 case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break;
379 case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break;
380 case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break;
381 case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break;
382 case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break;
383 case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break;
384 case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break;
385 case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break;
386 case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
387 case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
388 case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
389 case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
391 llvm_unreachable("unsupported section alignment");
394 // Bind internal COFF section to MC section.
395 coff_section->MCData = &SectionData;
396 SectionMap[&SectionData.getSection()] = coff_section;
399 /// This function takes a section data object from the assembler
400 /// and creates the associated COFF symbol staging object.
401 void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
402 MCAssembler &Assembler,
403 const MCAsmLayout &Layout) {
404 MCSymbol const &Symbol = SymbolData.getSymbol();
405 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol);
406 SymbolMap[&Symbol] = coff_symbol;
408 if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
409 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
411 if (Symbol.isVariable()) {
412 const MCSymbolRefExpr *SymRef =
413 dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue());
416 report_fatal_error("Weak externals may only alias symbols");
418 coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol());
420 std::string WeakName = std::string(".weak.")
421 + Symbol.getName().str()
423 COFFSymbol *WeakDefault = createSymbol(WeakName);
424 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
425 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
426 WeakDefault->Data.Type = 0;
427 WeakDefault->Data.Value = 0;
428 coff_symbol->Other = WeakDefault;
431 // Setup the Weak External auxiliary symbol.
432 coff_symbol->Aux.resize(1);
433 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
434 coff_symbol->Aux[0].AuxType = ATWeakExternal;
435 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
436 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
437 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
439 coff_symbol->MCData = &SymbolData;
441 const MCSymbolData &ResSymData =
442 Assembler.getSymbolData(Symbol.AliasedSymbol());
444 if (Symbol.isVariable()) {
446 if (Symbol.getVariableValue()->EvaluateAsAbsolute(Addr, Layout))
447 coff_symbol->Data.Value = Addr;
450 coff_symbol->Data.Type = (ResSymData.getFlags() & 0x0000FFFF) >> 0;
451 coff_symbol->Data.StorageClass = (ResSymData.getFlags() & 0x00FF0000) >> 16;
453 // If no storage class was specified in the streamer, define it here.
454 if (coff_symbol->Data.StorageClass == 0) {
455 bool external = ResSymData.isExternal() || (ResSymData.Fragment == NULL);
457 coff_symbol->Data.StorageClass =
458 external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC;
461 if (Symbol.isAbsolute() || Symbol.AliasedSymbol().isVariable())
462 coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
463 else if (ResSymData.Fragment != NULL)
464 coff_symbol->Section =
465 SectionMap[&ResSymData.Fragment->getParent()->getSection()];
467 coff_symbol->MCData = &ResSymData;
471 // Maximum offsets for different string table entry encodings.
472 static const unsigned Max6DecimalOffset = 999999;
473 static const unsigned Max7DecimalOffset = 9999999;
474 static const uint64_t MaxBase64Offset = 0xFFFFFFFFFULL; // 64^6, including 0
476 // Encode a string table entry offset in base 64, padded to 6 chars, and
477 // prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
478 // Buffer must be at least 8 bytes large. No terminating null appended.
479 static void encodeBase64StringEntry(char* Buffer, uint64_t Value) {
480 assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
481 "Illegal section name encoding for value");
483 static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
484 "abcdefghijklmnopqrstuvwxyz"
490 char* Ptr = Buffer + 7;
491 for (unsigned i = 0; i < 6; ++i) {
492 unsigned Rem = Value % 64;
494 *(Ptr--) = Alphabet[Rem];
498 /// making a section real involves assigned it a number and putting
499 /// name into the string table if needed
500 void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
501 if (S.Name.size() > COFF::NameSize) {
502 uint64_t StringTableEntry = Strings.insert(S.Name.c_str());
504 if (StringTableEntry <= Max6DecimalOffset) {
505 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
506 } else if (StringTableEntry <= Max7DecimalOffset) {
507 // With seven digits, we have to skip the terminating null. Because
508 // sprintf always appends it, we use a larger temporary buffer.
509 char buffer[9] = { };
510 std::sprintf(buffer, "/%d", unsigned(StringTableEntry));
511 std::memcpy(S.Header.Name, buffer, 8);
512 } else if (StringTableEntry <= MaxBase64Offset) {
513 // Starting with 10,000,000, offsets are encoded as base64.
514 encodeBase64StringEntry(S.Header.Name, StringTableEntry);
516 report_fatal_error("COFF string table is greater than 64 GB.");
519 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
522 S.Symbol->Data.SectionNumber = S.Number;
523 S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
526 void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
527 if (S.Name.size() > COFF::NameSize) {
528 size_t StringTableEntry = Strings.insert(S.Name.c_str());
530 S.set_name_offset(StringTableEntry);
532 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
536 bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
538 // This doesn't seem to be right. Strings referred to from the .data section
539 // need symbols so they can be linked to code in the .text section right?
541 // return Asm.isSymbolLinkerVisible (&SymbolData);
543 // For now, all non-variable symbols are exported,
544 // the linker will sort the rest out for us.
545 return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable();
548 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
549 return (S->Header.Characteristics
550 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
553 //------------------------------------------------------------------------------
554 // entity writing methods
556 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
557 WriteLE16(Header.Machine);
558 WriteLE16(Header.NumberOfSections);
559 WriteLE32(Header.TimeDateStamp);
560 WriteLE32(Header.PointerToSymbolTable);
561 WriteLE32(Header.NumberOfSymbols);
562 WriteLE16(Header.SizeOfOptionalHeader);
563 WriteLE16(Header.Characteristics);
566 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
567 WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
568 WriteLE32(S->Data.Value);
569 WriteLE16(S->Data.SectionNumber);
570 WriteLE16(S->Data.Type);
571 Write8(S->Data.StorageClass);
572 Write8(S->Data.NumberOfAuxSymbols);
573 WriteAuxiliarySymbols(S->Aux);
576 void WinCOFFObjectWriter::WriteAuxiliarySymbols(
577 const COFFSymbol::AuxiliarySymbols &S) {
578 for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
581 case ATFunctionDefinition:
582 WriteLE32(i->Aux.FunctionDefinition.TagIndex);
583 WriteLE32(i->Aux.FunctionDefinition.TotalSize);
584 WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
585 WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
586 WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
588 case ATbfAndefSymbol:
589 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
590 WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
591 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
592 WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
593 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
596 WriteLE32(i->Aux.WeakExternal.TagIndex);
597 WriteLE32(i->Aux.WeakExternal.Characteristics);
598 WriteZeros(sizeof(i->Aux.WeakExternal.unused));
601 WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
602 sizeof(i->Aux.File.FileName)));
604 case ATSectionDefinition:
605 WriteLE32(i->Aux.SectionDefinition.Length);
606 WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
607 WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
608 WriteLE32(i->Aux.SectionDefinition.CheckSum);
609 WriteLE16(i->Aux.SectionDefinition.Number);
610 Write8(i->Aux.SectionDefinition.Selection);
611 WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
617 void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
618 WriteBytes(StringRef(S.Name, COFF::NameSize));
620 WriteLE32(S.VirtualSize);
621 WriteLE32(S.VirtualAddress);
622 WriteLE32(S.SizeOfRawData);
623 WriteLE32(S.PointerToRawData);
624 WriteLE32(S.PointerToRelocations);
625 WriteLE32(S.PointerToLineNumbers);
626 WriteLE16(S.NumberOfRelocations);
627 WriteLE16(S.NumberOfLineNumbers);
628 WriteLE32(S.Characteristics);
631 void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
632 WriteLE32(R.VirtualAddress);
633 WriteLE32(R.SymbolTableIndex);
637 ////////////////////////////////////////////////////////////////////////////////
638 // MCObjectWriter interface implementations
640 void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
641 const MCAsmLayout &Layout) {
642 // "Define" each section & symbol. This creates section & symbol
643 // entries in the staging area.
645 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
648 for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
649 e = Asm.symbol_end();
651 if (ExportSymbol(*i, Asm)) {
652 DefineSymbol(*i, Asm, Layout);
657 void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
658 const MCAsmLayout &Layout,
659 const MCFragment *Fragment,
660 const MCFixup &Fixup,
662 uint64_t &FixedValue) {
663 assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
665 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
666 const MCSymbol &A = Symbol.AliasedSymbol();
667 if (!Asm.hasSymbolData(A))
668 Asm.getContext().FatalError(
670 Twine("symbol '") + A.getName() + "' can not be undefined");
672 MCSymbolData &A_SD = Asm.getSymbolData(A);
674 MCSectionData const *SectionData = Fragment->getParent();
676 // Mark this symbol as requiring an entry in the symbol table.
677 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
678 "Section must already have been defined in ExecutePostLayoutBinding!");
679 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
680 "Symbol must already have been defined in ExecutePostLayoutBinding!");
682 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
683 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
684 const MCSymbolRefExpr *SymB = Target.getSymB();
685 bool CrossSection = false;
688 const MCSymbol *B = &SymB->getSymbol();
689 MCSymbolData &B_SD = Asm.getSymbolData(*B);
690 if (!B_SD.getFragment())
691 Asm.getContext().FatalError(
693 Twine("symbol '") + B->getName() +
694 "' can not be undefined in a subtraction expression");
696 if (!A_SD.getFragment())
697 Asm.getContext().FatalError(
699 Twine("symbol '") + Symbol.getName() +
700 "' can not be undefined in a subtraction expression");
702 CrossSection = &Symbol.getSection() != &B->getSection();
704 // Offset of the symbol in the section
705 int64_t a = Layout.getSymbolOffset(&B_SD);
707 // Ofeset of the relocation in the section
708 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
711 // In the case where we have SymbA and SymB, we just need to store the delta
712 // between the two symbols. Update FixedValue to account for the delta, and
713 // skip recording the relocation.
717 FixedValue = Target.getConstant();
720 COFFRelocation Reloc;
722 Reloc.Data.SymbolTableIndex = 0;
723 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
725 // Turn relocations for temporary symbols into section relocations.
726 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
727 Reloc.Symb = coff_symbol->Section->Symbol;
728 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
729 + coff_symbol->MCData->getOffset();
731 Reloc.Symb = coff_symbol;
733 ++Reloc.Symb->Relocations;
735 Reloc.Data.VirtualAddress += Fixup.getOffset();
736 Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup,
739 // FIXME: Can anyone explain what this does other than adjust for the size
741 if (Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32 ||
742 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32)
745 coff_section->Relocations.push_back(Reloc);
748 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
749 const MCAsmLayout &Layout) {
750 // Assign symbol and section indexes and offsets.
751 Header.NumberOfSections = 0;
753 DenseMap<COFFSection *, uint16_t> SectionIndices;
754 for (sections::iterator i = Sections.begin(),
755 e = Sections.end(); i != e; i++) {
756 if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
757 size_t Number = ++Header.NumberOfSections;
758 SectionIndices[*i] = Number;
759 MakeSectionReal(**i, Number);
765 Header.NumberOfSymbols = 0;
767 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
768 COFFSymbol *coff_symbol = *i;
769 MCSymbolData const *SymbolData = coff_symbol->MCData;
771 // Update section number & offset for symbols that have them.
772 if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
773 assert(coff_symbol->Section != NULL);
775 coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
776 coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
777 + SymbolData->Offset;
780 if (coff_symbol->should_keep()) {
781 MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
783 // Update auxiliary symbol info.
784 coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
785 Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
787 coff_symbol->Index = -1;
790 // Fixup weak external references.
791 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
792 COFFSymbol *coff_symbol = *i;
793 if (coff_symbol->Other != NULL) {
794 assert(coff_symbol->Index != -1);
795 assert(coff_symbol->Aux.size() == 1 &&
796 "Symbol must contain one aux symbol!");
797 assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
798 "Symbol's aux symbol must be a Weak External!");
799 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
803 // Fixup associative COMDAT sections.
804 for (sections::iterator i = Sections.begin(),
805 e = Sections.end(); i != e; i++) {
806 if ((*i)->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
807 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
810 const MCSectionCOFF &MCSec = static_cast<const MCSectionCOFF &>(
811 (*i)->MCData->getSection());
813 COFFSection *Assoc = SectionMap.lookup(MCSec.getAssocSection());
815 report_fatal_error(Twine("Missing associated COMDAT section ") +
816 MCSec.getAssocSection()->getSectionName() +
817 " for section " + MCSec.getSectionName());
820 // Skip this section if the associated section is unused.
821 if (Assoc->Number == -1)
824 (*i)->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
828 // Assign file offsets to COFF object file structures.
832 offset += COFF::HeaderSize;
833 offset += COFF::SectionSize * Header.NumberOfSections;
835 for (MCAssembler::const_iterator i = Asm.begin(),
838 COFFSection *Sec = SectionMap[&i->getSection()];
840 if (Sec->Number == -1)
843 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);
845 if (IsPhysicalSection(Sec)) {
846 Sec->Header.PointerToRawData = offset;
848 offset += Sec->Header.SizeOfRawData;
851 if (Sec->Relocations.size() > 0) {
852 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
854 if (RelocationsOverflow) {
855 // Signal overflow by setting NumberOfSections to max value. Actual
856 // size is found in reloc #0. Microsoft tools understand this.
857 Sec->Header.NumberOfRelocations = 0xffff;
859 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
861 Sec->Header.PointerToRelocations = offset;
863 if (RelocationsOverflow) {
864 // Reloc #0 will contain actual count, so make room for it.
865 offset += COFF::RelocationSize;
868 offset += COFF::RelocationSize * Sec->Relocations.size();
870 for (relocations::iterator cr = Sec->Relocations.begin(),
871 er = Sec->Relocations.end();
873 assert((*cr).Symb->Index != -1);
874 (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
878 assert(Sec->Symbol->Aux.size() == 1
879 && "Section's symbol must have one aux!");
880 AuxSymbol &Aux = Sec->Symbol->Aux[0];
881 assert(Aux.AuxType == ATSectionDefinition &&
882 "Section's symbol's aux symbol must be a Section Definition!");
883 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
884 Aux.Aux.SectionDefinition.NumberOfRelocations =
885 Sec->Header.NumberOfRelocations;
886 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
887 Sec->Header.NumberOfLineNumbers;
890 Header.PointerToSymbolTable = offset;
892 // We want a deterministic output. It looks like GNU as also writes 0 in here.
893 Header.TimeDateStamp = 0;
895 // Write it all to disk...
896 WriteFileHeader(Header);
899 sections::iterator i, ie;
900 MCAssembler::const_iterator j, je;
902 for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
903 if ((*i)->Number != -1) {
904 if ((*i)->Relocations.size() >= 0xffff) {
905 (*i)->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
907 WriteSectionHeader((*i)->Header);
910 for (i = Sections.begin(), ie = Sections.end(),
911 j = Asm.begin(), je = Asm.end();
912 (i != ie) && (j != je); ++i, ++j) {
914 if ((*i)->Number == -1)
917 if ((*i)->Header.PointerToRawData != 0) {
918 assert(OS.tell() == (*i)->Header.PointerToRawData &&
919 "Section::PointerToRawData is insane!");
921 Asm.writeSectionData(j, Layout);
924 if ((*i)->Relocations.size() > 0) {
925 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
926 "Section::PointerToRelocations is insane!");
928 if ((*i)->Relocations.size() >= 0xffff) {
929 // In case of overflow, write actual relocation count as first
930 // relocation. Including the synthetic reloc itself (+ 1).
932 r.VirtualAddress = (*i)->Relocations.size() + 1;
933 r.SymbolTableIndex = 0;
938 for (relocations::const_iterator k = (*i)->Relocations.begin(),
939 ke = (*i)->Relocations.end();
941 WriteRelocation(k->Data);
944 assert((*i)->Header.PointerToRelocations == 0 &&
945 "Section::PointerToRelocations is insane!");
949 assert(OS.tell() == Header.PointerToSymbolTable &&
950 "Header::PointerToSymbolTable is insane!");
952 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
953 if ((*i)->Index != -1)
956 OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
959 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :
963 // Pin the vtable to this file.
964 void MCWinCOFFObjectTargetWriter::anchor() {}
966 //------------------------------------------------------------------------------
967 // WinCOFFObjectWriter factory function
970 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
972 return new WinCOFFObjectWriter(MOTW, OS);