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 // Encode a string table entry offset in base 64, padded to 6 chars, and
472 // prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
473 // Buffer must be at least 8 bytes large. No terminating null appended.
474 static void encodeBase64StringEntry(char* Buffer, uint64_t Value) {
475 assert(Value > 9999999 && Value <= 0xFFFFFFFFF &&
476 "Illegal section name encoding for value");
478 static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
479 "abcdefghijklmnopqrstuvwxyz"
485 char* Ptr = Buffer + 7;
486 for (unsigned i = 0; i < 6; ++i) {
487 unsigned Rem = Value % 64;
489 *(Ptr--) = Alphabet[Rem];
493 /// making a section real involves assigned it a number and putting
494 /// name into the string table if needed
495 void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
496 if (S.Name.size() > COFF::NameSize) {
497 const unsigned Max6DecimalSize = 999999;
498 const unsigned Max7DecimalSize = 9999999;
499 const uint64_t MaxBase64Size = 0xFFFFFFFFF; // 64^6, including 0
500 uint64_t StringTableEntry = Strings.insert(S.Name.c_str());
502 if (StringTableEntry <= Max6DecimalSize) {
503 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
504 } else if (StringTableEntry <= Max7DecimalSize) {
505 // With seven digits, we have to skip the terminating null. Because
506 // sprintf always appends it, we use a larger temporary buffer.
507 char buffer[9] = { };
508 std::sprintf(buffer, "/%d", unsigned(StringTableEntry));
509 std::memcpy(S.Header.Name, buffer, 8);
510 } else if (StringTableEntry <= MaxBase64Size) {
511 // Starting with 10,000,000, offsets are encoded as base64.
512 encodeBase64StringEntry(S.Header.Name, StringTableEntry);
514 report_fatal_error("COFF string table is greater than 64 GB.");
517 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
520 S.Symbol->Data.SectionNumber = S.Number;
521 S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
524 void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
525 if (S.Name.size() > COFF::NameSize) {
526 size_t StringTableEntry = Strings.insert(S.Name.c_str());
528 S.set_name_offset(StringTableEntry);
530 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
534 bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
536 // This doesn't seem to be right. Strings referred to from the .data section
537 // need symbols so they can be linked to code in the .text section right?
539 // return Asm.isSymbolLinkerVisible (&SymbolData);
541 // For now, all non-variable symbols are exported,
542 // the linker will sort the rest out for us.
543 return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable();
546 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
547 return (S->Header.Characteristics
548 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
551 //------------------------------------------------------------------------------
552 // entity writing methods
554 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
555 WriteLE16(Header.Machine);
556 WriteLE16(Header.NumberOfSections);
557 WriteLE32(Header.TimeDateStamp);
558 WriteLE32(Header.PointerToSymbolTable);
559 WriteLE32(Header.NumberOfSymbols);
560 WriteLE16(Header.SizeOfOptionalHeader);
561 WriteLE16(Header.Characteristics);
564 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
565 WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
566 WriteLE32(S->Data.Value);
567 WriteLE16(S->Data.SectionNumber);
568 WriteLE16(S->Data.Type);
569 Write8(S->Data.StorageClass);
570 Write8(S->Data.NumberOfAuxSymbols);
571 WriteAuxiliarySymbols(S->Aux);
574 void WinCOFFObjectWriter::WriteAuxiliarySymbols(
575 const COFFSymbol::AuxiliarySymbols &S) {
576 for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
579 case ATFunctionDefinition:
580 WriteLE32(i->Aux.FunctionDefinition.TagIndex);
581 WriteLE32(i->Aux.FunctionDefinition.TotalSize);
582 WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
583 WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
584 WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
586 case ATbfAndefSymbol:
587 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
588 WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
589 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
590 WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
591 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
594 WriteLE32(i->Aux.WeakExternal.TagIndex);
595 WriteLE32(i->Aux.WeakExternal.Characteristics);
596 WriteZeros(sizeof(i->Aux.WeakExternal.unused));
599 WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
600 sizeof(i->Aux.File.FileName)));
602 case ATSectionDefinition:
603 WriteLE32(i->Aux.SectionDefinition.Length);
604 WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
605 WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
606 WriteLE32(i->Aux.SectionDefinition.CheckSum);
607 WriteLE16(i->Aux.SectionDefinition.Number);
608 Write8(i->Aux.SectionDefinition.Selection);
609 WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
615 void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
616 WriteBytes(StringRef(S.Name, COFF::NameSize));
618 WriteLE32(S.VirtualSize);
619 WriteLE32(S.VirtualAddress);
620 WriteLE32(S.SizeOfRawData);
621 WriteLE32(S.PointerToRawData);
622 WriteLE32(S.PointerToRelocations);
623 WriteLE32(S.PointerToLineNumbers);
624 WriteLE16(S.NumberOfRelocations);
625 WriteLE16(S.NumberOfLineNumbers);
626 WriteLE32(S.Characteristics);
629 void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
630 WriteLE32(R.VirtualAddress);
631 WriteLE32(R.SymbolTableIndex);
635 ////////////////////////////////////////////////////////////////////////////////
636 // MCObjectWriter interface implementations
638 void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
639 const MCAsmLayout &Layout) {
640 // "Define" each section & symbol. This creates section & symbol
641 // entries in the staging area.
643 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
646 for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
647 e = Asm.symbol_end();
649 if (ExportSymbol(*i, Asm)) {
650 DefineSymbol(*i, Asm, Layout);
655 void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
656 const MCAsmLayout &Layout,
657 const MCFragment *Fragment,
658 const MCFixup &Fixup,
660 uint64_t &FixedValue) {
661 assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
663 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
664 const MCSymbol &A = Symbol.AliasedSymbol();
665 if (!Asm.hasSymbolData(A))
666 Asm.getContext().FatalError(
668 Twine("symbol '") + A.getName() + "' can not be undefined");
670 MCSymbolData &A_SD = Asm.getSymbolData(A);
672 MCSectionData const *SectionData = Fragment->getParent();
674 // Mark this symbol as requiring an entry in the symbol table.
675 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
676 "Section must already have been defined in ExecutePostLayoutBinding!");
677 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
678 "Symbol must already have been defined in ExecutePostLayoutBinding!");
680 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
681 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
682 const MCSymbolRefExpr *SymB = Target.getSymB();
683 bool CrossSection = false;
686 const MCSymbol *B = &SymB->getSymbol();
687 MCSymbolData &B_SD = Asm.getSymbolData(*B);
688 if (!B_SD.getFragment())
689 Asm.getContext().FatalError(
691 Twine("symbol '") + B->getName() +
692 "' can not be undefined in a subtraction expression");
694 if (!A_SD.getFragment())
695 Asm.getContext().FatalError(
697 Twine("symbol '") + Symbol.getName() +
698 "' can not be undefined in a subtraction expression");
700 CrossSection = &Symbol.getSection() != &B->getSection();
702 // Offset of the symbol in the section
703 int64_t a = Layout.getSymbolOffset(&B_SD);
705 // Ofeset of the relocation in the section
706 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
709 // In the case where we have SymbA and SymB, we just need to store the delta
710 // between the two symbols. Update FixedValue to account for the delta, and
711 // skip recording the relocation.
715 FixedValue = Target.getConstant();
718 COFFRelocation Reloc;
720 Reloc.Data.SymbolTableIndex = 0;
721 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
723 // Turn relocations for temporary symbols into section relocations.
724 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
725 Reloc.Symb = coff_symbol->Section->Symbol;
726 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
727 + coff_symbol->MCData->getOffset();
729 Reloc.Symb = coff_symbol;
731 ++Reloc.Symb->Relocations;
733 Reloc.Data.VirtualAddress += Fixup.getOffset();
734 Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup,
737 // FIXME: Can anyone explain what this does other than adjust for the size
739 if (Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32 ||
740 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32)
743 coff_section->Relocations.push_back(Reloc);
746 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
747 const MCAsmLayout &Layout) {
748 // Assign symbol and section indexes and offsets.
749 Header.NumberOfSections = 0;
751 DenseMap<COFFSection *, uint16_t> SectionIndices;
752 for (sections::iterator i = Sections.begin(),
753 e = Sections.end(); i != e; i++) {
754 if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
755 size_t Number = ++Header.NumberOfSections;
756 SectionIndices[*i] = Number;
757 MakeSectionReal(**i, Number);
763 Header.NumberOfSymbols = 0;
765 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
766 COFFSymbol *coff_symbol = *i;
767 MCSymbolData const *SymbolData = coff_symbol->MCData;
769 // Update section number & offset for symbols that have them.
770 if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
771 assert(coff_symbol->Section != NULL);
773 coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
774 coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
775 + SymbolData->Offset;
778 if (coff_symbol->should_keep()) {
779 MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
781 // Update auxiliary symbol info.
782 coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
783 Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
785 coff_symbol->Index = -1;
788 // Fixup weak external references.
789 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
790 COFFSymbol *coff_symbol = *i;
791 if (coff_symbol->Other != NULL) {
792 assert(coff_symbol->Index != -1);
793 assert(coff_symbol->Aux.size() == 1 &&
794 "Symbol must contain one aux symbol!");
795 assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
796 "Symbol's aux symbol must be a Weak External!");
797 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
801 // Fixup associative COMDAT sections.
802 for (sections::iterator i = Sections.begin(),
803 e = Sections.end(); i != e; i++) {
804 if ((*i)->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
805 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
808 const MCSectionCOFF &MCSec = static_cast<const MCSectionCOFF &>(
809 (*i)->MCData->getSection());
811 COFFSection *Assoc = SectionMap.lookup(MCSec.getAssocSection());
813 report_fatal_error(Twine("Missing associated COMDAT section ") +
814 MCSec.getAssocSection()->getSectionName() +
815 " for section " + MCSec.getSectionName());
818 // Skip this section if the associated section is unused.
819 if (Assoc->Number == -1)
822 (*i)->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
826 // Assign file offsets to COFF object file structures.
830 offset += COFF::HeaderSize;
831 offset += COFF::SectionSize * Header.NumberOfSections;
833 for (MCAssembler::const_iterator i = Asm.begin(),
836 COFFSection *Sec = SectionMap[&i->getSection()];
838 if (Sec->Number == -1)
841 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);
843 if (IsPhysicalSection(Sec)) {
844 Sec->Header.PointerToRawData = offset;
846 offset += Sec->Header.SizeOfRawData;
849 if (Sec->Relocations.size() > 0) {
850 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
852 if (RelocationsOverflow) {
853 // Signal overflow by setting NumberOfSections to max value. Actual
854 // size is found in reloc #0. Microsoft tools understand this.
855 Sec->Header.NumberOfRelocations = 0xffff;
857 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
859 Sec->Header.PointerToRelocations = offset;
861 if (RelocationsOverflow) {
862 // Reloc #0 will contain actual count, so make room for it.
863 offset += COFF::RelocationSize;
866 offset += COFF::RelocationSize * Sec->Relocations.size();
868 for (relocations::iterator cr = Sec->Relocations.begin(),
869 er = Sec->Relocations.end();
871 assert((*cr).Symb->Index != -1);
872 (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
876 assert(Sec->Symbol->Aux.size() == 1
877 && "Section's symbol must have one aux!");
878 AuxSymbol &Aux = Sec->Symbol->Aux[0];
879 assert(Aux.AuxType == ATSectionDefinition &&
880 "Section's symbol's aux symbol must be a Section Definition!");
881 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
882 Aux.Aux.SectionDefinition.NumberOfRelocations =
883 Sec->Header.NumberOfRelocations;
884 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
885 Sec->Header.NumberOfLineNumbers;
888 Header.PointerToSymbolTable = offset;
890 // We want a deterministic output. It looks like GNU as also writes 0 in here.
891 Header.TimeDateStamp = 0;
893 // Write it all to disk...
894 WriteFileHeader(Header);
897 sections::iterator i, ie;
898 MCAssembler::const_iterator j, je;
900 for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
901 if ((*i)->Number != -1) {
902 if ((*i)->Relocations.size() >= 0xffff) {
903 (*i)->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
905 WriteSectionHeader((*i)->Header);
908 for (i = Sections.begin(), ie = Sections.end(),
909 j = Asm.begin(), je = Asm.end();
910 (i != ie) && (j != je); ++i, ++j) {
912 if ((*i)->Number == -1)
915 if ((*i)->Header.PointerToRawData != 0) {
916 assert(OS.tell() == (*i)->Header.PointerToRawData &&
917 "Section::PointerToRawData is insane!");
919 Asm.writeSectionData(j, Layout);
922 if ((*i)->Relocations.size() > 0) {
923 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
924 "Section::PointerToRelocations is insane!");
926 if ((*i)->Relocations.size() >= 0xffff) {
927 // In case of overflow, write actual relocation count as first
928 // relocation. Including the synthetic reloc itself (+ 1).
930 r.VirtualAddress = (*i)->Relocations.size() + 1;
931 r.SymbolTableIndex = 0;
936 for (relocations::const_iterator k = (*i)->Relocations.begin(),
937 ke = (*i)->Relocations.end();
939 WriteRelocation(k->Data);
942 assert((*i)->Header.PointerToRelocations == 0 &&
943 "Section::PointerToRelocations is insane!");
947 assert(OS.tell() == Header.PointerToSymbolTable &&
948 "Header::PointerToSymbolTable is insane!");
950 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
951 if ((*i)->Index != -1)
954 OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
957 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :
961 // Pin the vtable to this file.
962 void MCWinCOFFObjectTargetWriter::anchor() {}
964 //------------------------------------------------------------------------------
965 // WinCOFFObjectWriter factory function
968 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
970 return new WinCOFFObjectWriter(MOTW, OS);