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/StringMap.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/ADT/Twine.h"
21 #include "llvm/MC/MCAsmLayout.h"
22 #include "llvm/MC/MCAssembler.h"
23 #include "llvm/MC/MCContext.h"
24 #include "llvm/MC/MCExpr.h"
25 #include "llvm/MC/MCObjectWriter.h"
26 #include "llvm/MC/MCSection.h"
27 #include "llvm/MC/MCSectionCOFF.h"
28 #include "llvm/MC/MCSymbol.h"
29 #include "llvm/MC/MCValue.h"
30 #include "llvm/Support/COFF.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Support/ErrorHandling.h"
33 #include "llvm/Support/TimeValue.h"
39 typedef SmallString<COFF::NameSize> name;
50 AuxiliaryType AuxType;
61 typedef SmallVector<AuxSymbol, 1> AuxiliarySymbols;
70 MCSymbolData const *MCData;
72 COFFSymbol(StringRef name);
74 void set_name_offset(uint32_t Offset);
76 bool should_keep() const;
79 // This class contains staging data for a COFF relocation entry.
80 struct COFFRelocation {
81 COFF::relocation Data;
84 COFFRelocation() : Symb(NULL) {}
85 static size_t size() { return COFF::RelocationSize; }
88 typedef std::vector<COFFRelocation> relocations;
96 MCSectionData const *MCData;
98 relocations Relocations;
100 COFFSection(StringRef name);
101 static size_t size();
104 // This class holds the COFF string table.
106 typedef StringMap<size_t> map;
109 void update_length();
111 std::vector<char> Data;
115 size_t insert(StringRef String);
118 class WinCOFFObjectWriter : public MCObjectWriter {
121 typedef std::vector<COFFSymbol*> symbols;
122 typedef std::vector<COFFSection*> sections;
124 typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map;
125 typedef DenseMap<MCSection const *, COFFSection *> section_map;
127 std::unique_ptr<MCWinCOFFObjectTargetWriter> TargetObjectWriter;
129 // Root level file contents.
135 // Maps used during object file creation.
136 section_map SectionMap;
137 symbol_map SymbolMap;
139 WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, raw_ostream &OS);
140 virtual ~WinCOFFObjectWriter();
142 COFFSymbol *createSymbol(StringRef Name);
143 COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol);
144 COFFSection *createSection(StringRef Name);
146 template <typename object_t, typename list_t>
147 object_t *createCOFFEntity(StringRef Name, list_t &List);
149 void DefineSection(MCSectionData const &SectionData);
150 void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler,
151 const MCAsmLayout &Layout);
153 void MakeSymbolReal(COFFSymbol &S, size_t Index);
154 void MakeSectionReal(COFFSection &S, size_t Number);
156 bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm);
158 bool IsPhysicalSection(COFFSection *S);
160 // Entity writing methods.
162 void WriteFileHeader(const COFF::header &Header);
163 void WriteSymbol(const COFFSymbol *S);
164 void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
165 void WriteSectionHeader(const COFF::section &S);
166 void WriteRelocation(const COFF::relocation &R);
168 // MCObjectWriter interface implementation.
170 void ExecutePostLayoutBinding(MCAssembler &Asm,
171 const MCAsmLayout &Layout) override;
173 void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
174 const MCFragment *Fragment, const MCFixup &Fixup,
175 MCValue Target, bool &IsPCRel,
176 uint64_t &FixedValue) override;
178 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
182 static inline void write_uint32_le(void *Data, uint32_t const &Value) {
183 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
184 Ptr[0] = (Value & 0x000000FF) >> 0;
185 Ptr[1] = (Value & 0x0000FF00) >> 8;
186 Ptr[2] = (Value & 0x00FF0000) >> 16;
187 Ptr[3] = (Value & 0xFF000000) >> 24;
190 //------------------------------------------------------------------------------
191 // Symbol class implementation
193 COFFSymbol::COFFSymbol(StringRef name)
194 : Name(name.begin(), name.end())
199 memset(&Data, 0, sizeof(Data));
202 size_t COFFSymbol::size() const {
203 return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
206 // In the case that the name does not fit within 8 bytes, the offset
207 // into the string table is stored in the last 4 bytes instead, leaving
208 // the first 4 bytes as 0.
209 void COFFSymbol::set_name_offset(uint32_t Offset) {
210 write_uint32_le(Data.Name + 0, 0);
211 write_uint32_le(Data.Name + 4, Offset);
214 /// logic to decide if the symbol should be reported in the symbol table
215 bool COFFSymbol::should_keep() const {
216 // no section means its external, keep it
220 // if it has relocations pointing at it, keep it
221 if (Relocations > 0) {
222 assert(Section->Number != -1 && "Sections with relocations must be real!");
226 // if the section its in is being droped, drop it
227 if (Section->Number == -1)
230 // if it is the section symbol, keep it
231 if (Section->Symbol == this)
234 // if its temporary, drop it
235 if (MCData && MCData->getSymbol().isTemporary())
238 // otherwise, keep it
242 //------------------------------------------------------------------------------
243 // Section class implementation
245 COFFSection::COFFSection(StringRef name)
249 memset(&Header, 0, sizeof(Header));
252 size_t COFFSection::size() {
253 return COFF::SectionSize;
256 //------------------------------------------------------------------------------
257 // StringTable class implementation
259 /// Write the length of the string table into Data.
260 /// The length of the string table includes uint32 length header.
261 void StringTable::update_length() {
262 write_uint32_le(&Data.front(), Data.size());
265 StringTable::StringTable() {
266 // The string table data begins with the length of the entire string table
267 // including the length header. Allocate space for this header.
272 size_t StringTable::size() const {
276 /// Add String to the table iff it is not already there.
277 /// @returns the index into the string table where the string is now located.
278 size_t StringTable::insert(StringRef String) {
279 map::iterator i = Map.find(String);
284 size_t Offset = Data.size();
286 // Insert string data into string table.
287 Data.insert(Data.end(), String.begin(), String.end());
288 Data.push_back('\0');
290 // Put a reference to it in the map.
291 Map[String] = Offset;
293 // Update the internal length field.
299 //------------------------------------------------------------------------------
300 // WinCOFFObjectWriter class implementation
302 WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
304 : MCObjectWriter(OS, true)
305 , TargetObjectWriter(MOTW) {
306 memset(&Header, 0, sizeof(Header));
308 Header.Machine = TargetObjectWriter->getMachine();
311 WinCOFFObjectWriter::~WinCOFFObjectWriter() {
312 for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I)
314 for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I)
318 COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
319 return createCOFFEntity<COFFSymbol>(Name, Symbols);
322 COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
323 symbol_map::iterator i = SymbolMap.find(Symbol);
324 if (i != SymbolMap.end())
326 COFFSymbol *RetSymbol
327 = createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
328 SymbolMap[Symbol] = RetSymbol;
332 COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) {
333 return createCOFFEntity<COFFSection>(Name, Sections);
336 /// A template used to lookup or create a symbol/section, and initialize it if
338 template <typename object_t, typename list_t>
339 object_t *WinCOFFObjectWriter::createCOFFEntity(StringRef Name,
341 object_t *Object = new object_t(Name);
343 List.push_back(Object);
348 /// This function takes a section data object from the assembler
349 /// and creates the associated COFF section staging object.
350 void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
351 assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
352 && "Got non-COFF section in the COFF backend!");
353 // FIXME: Not sure how to verify this (at least in a debug build).
354 MCSectionCOFF const &Sec =
355 static_cast<MCSectionCOFF const &>(SectionData.getSection());
357 COFFSection *coff_section = createSection(Sec.getSectionName());
358 COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
360 coff_section->Symbol = coff_symbol;
361 coff_symbol->Section = coff_section;
362 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
364 // In this case the auxiliary symbol is a Section Definition.
365 coff_symbol->Aux.resize(1);
366 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
367 coff_symbol->Aux[0].AuxType = ATSectionDefinition;
368 coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
370 coff_section->Header.Characteristics = Sec.getCharacteristics();
372 uint32_t &Characteristics = coff_section->Header.Characteristics;
373 switch (SectionData.getAlignment()) {
374 case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break;
375 case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break;
376 case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break;
377 case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break;
378 case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break;
379 case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break;
380 case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break;
381 case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break;
382 case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break;
383 case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break;
384 case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
385 case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
386 case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
387 case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
389 llvm_unreachable("unsupported section alignment");
392 // Bind internal COFF section to MC section.
393 coff_section->MCData = &SectionData;
394 SectionMap[&SectionData.getSection()] = coff_section;
397 /// This function takes a symbol data object from the assembler
398 /// and creates the associated COFF symbol staging object.
399 void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
400 MCAssembler &Assembler,
401 const MCAsmLayout &Layout) {
402 MCSymbol const &Symbol = SymbolData.getSymbol();
403 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol);
404 SymbolMap[&Symbol] = coff_symbol;
406 if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
407 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
409 if (Symbol.isVariable()) {
410 const MCSymbolRefExpr *SymRef =
411 dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue());
414 report_fatal_error("Weak externals may only alias symbols");
416 coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol());
418 std::string WeakName = std::string(".weak.")
419 + Symbol.getName().str()
421 COFFSymbol *WeakDefault = createSymbol(WeakName);
422 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
423 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
424 WeakDefault->Data.Type = 0;
425 WeakDefault->Data.Value = 0;
426 coff_symbol->Other = WeakDefault;
429 // Setup the Weak External auxiliary symbol.
430 coff_symbol->Aux.resize(1);
431 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
432 coff_symbol->Aux[0].AuxType = ATWeakExternal;
433 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
434 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
435 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
437 coff_symbol->MCData = &SymbolData;
439 const MCSymbolData &ResSymData =
440 Assembler.getSymbolData(Symbol.AliasedSymbol());
442 if (Symbol.isVariable()) {
444 if (Symbol.getVariableValue()->EvaluateAsAbsolute(Addr, Layout))
445 coff_symbol->Data.Value = Addr;
446 } else if (SymbolData.isExternal() && SymbolData.isCommon()) {
447 coff_symbol->Data.Value = SymbolData.getCommonSize();
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,
663 uint64_t &FixedValue) {
664 assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
666 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
667 const MCSymbol &A = Symbol.AliasedSymbol();
668 if (!Asm.hasSymbolData(A))
669 Asm.getContext().FatalError(
671 Twine("symbol '") + A.getName() + "' can not be undefined");
673 MCSymbolData &A_SD = Asm.getSymbolData(A);
675 MCSectionData const *SectionData = Fragment->getParent();
677 // Mark this symbol as requiring an entry in the symbol table.
678 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
679 "Section must already have been defined in ExecutePostLayoutBinding!");
680 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
681 "Symbol must already have been defined in ExecutePostLayoutBinding!");
683 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
684 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
685 const MCSymbolRefExpr *SymB = Target.getSymB();
686 bool CrossSection = false;
689 const MCSymbol *B = &SymB->getSymbol();
690 MCSymbolData &B_SD = Asm.getSymbolData(*B);
691 if (!B_SD.getFragment())
692 Asm.getContext().FatalError(
694 Twine("symbol '") + B->getName() +
695 "' can not be undefined in a subtraction expression");
697 if (!A_SD.getFragment())
698 Asm.getContext().FatalError(
700 Twine("symbol '") + Symbol.getName() +
701 "' can not be undefined in a subtraction expression");
703 CrossSection = &Symbol.getSection() != &B->getSection();
705 // Offset of the symbol in the section
706 int64_t a = Layout.getSymbolOffset(&B_SD);
708 // Ofeset of the relocation in the section
709 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
712 // In the case where we have SymbA and SymB, we just need to store the delta
713 // between the two symbols. Update FixedValue to account for the delta, and
714 // skip recording the relocation.
718 FixedValue = Target.getConstant();
721 COFFRelocation Reloc;
723 Reloc.Data.SymbolTableIndex = 0;
724 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
726 // Turn relocations for temporary symbols into section relocations.
727 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
728 Reloc.Symb = coff_symbol->Section->Symbol;
729 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
730 + coff_symbol->MCData->getOffset();
732 Reloc.Symb = coff_symbol;
734 ++Reloc.Symb->Relocations;
736 Reloc.Data.VirtualAddress += Fixup.getOffset();
737 Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup,
740 // FIXME: Can anyone explain what this does other than adjust for the size
742 if (Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32 ||
743 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32)
746 coff_section->Relocations.push_back(Reloc);
749 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
750 const MCAsmLayout &Layout) {
751 // Assign symbol and section indexes and offsets.
752 Header.NumberOfSections = 0;
754 DenseMap<COFFSection *, uint16_t> SectionIndices;
755 for (sections::iterator i = Sections.begin(),
756 e = Sections.end(); i != e; i++) {
757 if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
758 size_t Number = ++Header.NumberOfSections;
759 SectionIndices[*i] = Number;
760 MakeSectionReal(**i, Number);
766 Header.NumberOfSymbols = 0;
768 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
769 COFFSymbol *coff_symbol = *i;
770 MCSymbolData const *SymbolData = coff_symbol->MCData;
772 // Update section number & offset for symbols that have them.
773 if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
774 assert(coff_symbol->Section != NULL);
776 coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
777 coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
778 + SymbolData->Offset;
781 if (coff_symbol->should_keep()) {
782 MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
784 // Update auxiliary symbol info.
785 coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
786 Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
788 coff_symbol->Index = -1;
791 // Fixup weak external references.
792 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
793 COFFSymbol *coff_symbol = *i;
794 if (coff_symbol->Other != NULL) {
795 assert(coff_symbol->Index != -1);
796 assert(coff_symbol->Aux.size() == 1 &&
797 "Symbol must contain one aux symbol!");
798 assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
799 "Symbol's aux symbol must be a Weak External!");
800 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
804 // Fixup associative COMDAT sections.
805 for (sections::iterator i = Sections.begin(),
806 e = Sections.end(); i != e; i++) {
807 if ((*i)->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
808 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
811 const MCSectionCOFF &MCSec = static_cast<const MCSectionCOFF &>(
812 (*i)->MCData->getSection());
814 COFFSection *Assoc = SectionMap.lookup(MCSec.getAssocSection());
816 report_fatal_error(Twine("Missing associated COMDAT section ") +
817 MCSec.getAssocSection()->getSectionName() +
818 " for section " + MCSec.getSectionName());
821 // Skip this section if the associated section is unused.
822 if (Assoc->Number == -1)
825 (*i)->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
829 // Assign file offsets to COFF object file structures.
833 offset += COFF::HeaderSize;
834 offset += COFF::SectionSize * Header.NumberOfSections;
836 for (MCAssembler::const_iterator i = Asm.begin(),
839 COFFSection *Sec = SectionMap[&i->getSection()];
841 if (Sec->Number == -1)
844 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);
846 if (IsPhysicalSection(Sec)) {
847 Sec->Header.PointerToRawData = offset;
849 offset += Sec->Header.SizeOfRawData;
852 if (Sec->Relocations.size() > 0) {
853 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
855 if (RelocationsOverflow) {
856 // Signal overflow by setting NumberOfSections to max value. Actual
857 // size is found in reloc #0. Microsoft tools understand this.
858 Sec->Header.NumberOfRelocations = 0xffff;
860 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
862 Sec->Header.PointerToRelocations = offset;
864 if (RelocationsOverflow) {
865 // Reloc #0 will contain actual count, so make room for it.
866 offset += COFF::RelocationSize;
869 offset += COFF::RelocationSize * Sec->Relocations.size();
871 for (relocations::iterator cr = Sec->Relocations.begin(),
872 er = Sec->Relocations.end();
874 assert((*cr).Symb->Index != -1);
875 (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
879 assert(Sec->Symbol->Aux.size() == 1
880 && "Section's symbol must have one aux!");
881 AuxSymbol &Aux = Sec->Symbol->Aux[0];
882 assert(Aux.AuxType == ATSectionDefinition &&
883 "Section's symbol's aux symbol must be a Section Definition!");
884 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
885 Aux.Aux.SectionDefinition.NumberOfRelocations =
886 Sec->Header.NumberOfRelocations;
887 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
888 Sec->Header.NumberOfLineNumbers;
891 Header.PointerToSymbolTable = offset;
893 // We want a deterministic output. It looks like GNU as also writes 0 in here.
894 Header.TimeDateStamp = 0;
896 // Write it all to disk...
897 WriteFileHeader(Header);
900 sections::iterator i, ie;
901 MCAssembler::const_iterator j, je;
903 for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
904 if ((*i)->Number != -1) {
905 if ((*i)->Relocations.size() >= 0xffff) {
906 (*i)->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
908 WriteSectionHeader((*i)->Header);
911 for (i = Sections.begin(), ie = Sections.end(),
912 j = Asm.begin(), je = Asm.end();
913 (i != ie) && (j != je); ++i, ++j) {
915 if ((*i)->Number == -1)
918 if ((*i)->Header.PointerToRawData != 0) {
919 assert(OS.tell() == (*i)->Header.PointerToRawData &&
920 "Section::PointerToRawData is insane!");
922 Asm.writeSectionData(j, Layout);
925 if ((*i)->Relocations.size() > 0) {
926 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
927 "Section::PointerToRelocations is insane!");
929 if ((*i)->Relocations.size() >= 0xffff) {
930 // In case of overflow, write actual relocation count as first
931 // relocation. Including the synthetic reloc itself (+ 1).
933 r.VirtualAddress = (*i)->Relocations.size() + 1;
934 r.SymbolTableIndex = 0;
939 for (relocations::const_iterator k = (*i)->Relocations.begin(),
940 ke = (*i)->Relocations.end();
942 WriteRelocation(k->Data);
945 assert((*i)->Header.PointerToRelocations == 0 &&
946 "Section::PointerToRelocations is insane!");
950 assert(OS.tell() == Header.PointerToSymbolTable &&
951 "Header::PointerToSymbolTable is insane!");
953 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
954 if ((*i)->Index != -1)
957 OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
960 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :
964 // Pin the vtable to this file.
965 void MCWinCOFFObjectTargetWriter::anchor() {}
967 //------------------------------------------------------------------------------
968 // WinCOFFObjectWriter factory function
971 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
973 return new WinCOFFObjectWriter(MOTW, OS);