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, const MCAsmLayout &Layout);
172 void RecordRelocation(const MCAssembler &Asm,
173 const MCAsmLayout &Layout,
174 const MCFragment *Fragment,
175 const MCFixup &Fixup,
177 uint64_t &FixedValue);
179 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
183 static inline void write_uint32_le(void *Data, uint32_t const &Value) {
184 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
185 Ptr[0] = (Value & 0x000000FF) >> 0;
186 Ptr[1] = (Value & 0x0000FF00) >> 8;
187 Ptr[2] = (Value & 0x00FF0000) >> 16;
188 Ptr[3] = (Value & 0xFF000000) >> 24;
191 //------------------------------------------------------------------------------
192 // Symbol class implementation
194 COFFSymbol::COFFSymbol(StringRef name)
195 : Name(name.begin(), name.end())
200 memset(&Data, 0, sizeof(Data));
203 size_t COFFSymbol::size() const {
204 return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
207 // In the case that the name does not fit within 8 bytes, the offset
208 // into the string table is stored in the last 4 bytes instead, leaving
209 // the first 4 bytes as 0.
210 void COFFSymbol::set_name_offset(uint32_t Offset) {
211 write_uint32_le(Data.Name + 0, 0);
212 write_uint32_le(Data.Name + 4, Offset);
215 /// logic to decide if the symbol should be reported in the symbol table
216 bool COFFSymbol::should_keep() const {
217 // no section means its external, keep it
221 // if it has relocations pointing at it, keep it
222 if (Relocations > 0) {
223 assert(Section->Number != -1 && "Sections with relocations must be real!");
227 // if the section its in is being droped, drop it
228 if (Section->Number == -1)
231 // if it is the section symbol, keep it
232 if (Section->Symbol == this)
235 // if its temporary, drop it
236 if (MCData && MCData->getSymbol().isTemporary())
239 // otherwise, keep it
243 //------------------------------------------------------------------------------
244 // Section class implementation
246 COFFSection::COFFSection(StringRef name)
250 memset(&Header, 0, sizeof(Header));
253 size_t COFFSection::size() {
254 return COFF::SectionSize;
257 //------------------------------------------------------------------------------
258 // StringTable class implementation
260 /// Write the length of the string table into Data.
261 /// The length of the string table includes uint32 length header.
262 void StringTable::update_length() {
263 write_uint32_le(&Data.front(), Data.size());
266 StringTable::StringTable() {
267 // The string table data begins with the length of the entire string table
268 // including the length header. Allocate space for this header.
273 size_t StringTable::size() const {
277 /// Add String to the table iff it is not already there.
278 /// @returns the index into the string table where the string is now located.
279 size_t StringTable::insert(StringRef String) {
280 map::iterator i = Map.find(String);
285 size_t Offset = Data.size();
287 // Insert string data into string table.
288 Data.insert(Data.end(), String.begin(), String.end());
289 Data.push_back('\0');
291 // Put a reference to it in the map.
292 Map[String] = Offset;
294 // Update the internal length field.
300 //------------------------------------------------------------------------------
301 // WinCOFFObjectWriter class implementation
303 WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
305 : MCObjectWriter(OS, true)
306 , TargetObjectWriter(MOTW) {
307 memset(&Header, 0, sizeof(Header));
309 Header.Machine = TargetObjectWriter->getMachine();
312 WinCOFFObjectWriter::~WinCOFFObjectWriter() {
313 for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I)
315 for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I)
319 COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
320 return createCOFFEntity<COFFSymbol>(Name, Symbols);
323 COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
324 symbol_map::iterator i = SymbolMap.find(Symbol);
325 if (i != SymbolMap.end())
327 COFFSymbol *RetSymbol
328 = createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
329 SymbolMap[Symbol] = RetSymbol;
333 COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) {
334 return createCOFFEntity<COFFSection>(Name, Sections);
337 /// A template used to lookup or create a symbol/section, and initialize it if
339 template <typename object_t, typename list_t>
340 object_t *WinCOFFObjectWriter::createCOFFEntity(StringRef Name,
342 object_t *Object = new object_t(Name);
344 List.push_back(Object);
349 /// This function takes a section data object from the assembler
350 /// and creates the associated COFF section staging object.
351 void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
352 assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
353 && "Got non-COFF section in the COFF backend!");
354 // FIXME: Not sure how to verify this (at least in a debug build).
355 MCSectionCOFF const &Sec =
356 static_cast<MCSectionCOFF const &>(SectionData.getSection());
358 COFFSection *coff_section = createSection(Sec.getSectionName());
359 COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
361 coff_section->Symbol = coff_symbol;
362 coff_symbol->Section = coff_section;
363 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
365 // In this case the auxiliary symbol is a Section Definition.
366 coff_symbol->Aux.resize(1);
367 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
368 coff_symbol->Aux[0].AuxType = ATSectionDefinition;
369 coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
371 coff_section->Header.Characteristics = Sec.getCharacteristics();
373 uint32_t &Characteristics = coff_section->Header.Characteristics;
374 switch (SectionData.getAlignment()) {
375 case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break;
376 case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break;
377 case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break;
378 case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break;
379 case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break;
380 case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break;
381 case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break;
382 case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break;
383 case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break;
384 case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break;
385 case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
386 case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
387 case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
388 case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
390 llvm_unreachable("unsupported section alignment");
393 // Bind internal COFF section to MC section.
394 coff_section->MCData = &SectionData;
395 SectionMap[&SectionData.getSection()] = coff_section;
398 /// This function takes a section data object from the assembler
399 /// and creates the associated COFF symbol staging object.
400 void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
401 MCAssembler &Assembler,
402 const MCAsmLayout &Layout) {
403 MCSymbol const &Symbol = SymbolData.getSymbol();
404 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol);
405 SymbolMap[&Symbol] = coff_symbol;
407 if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
408 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
410 if (Symbol.isVariable()) {
411 const MCSymbolRefExpr *SymRef =
412 dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue());
415 report_fatal_error("Weak externals may only alias symbols");
417 coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol());
419 std::string WeakName = std::string(".weak.")
420 + Symbol.getName().str()
422 COFFSymbol *WeakDefault = createSymbol(WeakName);
423 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
424 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
425 WeakDefault->Data.Type = 0;
426 WeakDefault->Data.Value = 0;
427 coff_symbol->Other = WeakDefault;
430 // Setup the Weak External auxiliary symbol.
431 coff_symbol->Aux.resize(1);
432 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
433 coff_symbol->Aux[0].AuxType = ATWeakExternal;
434 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
435 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
436 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
438 coff_symbol->MCData = &SymbolData;
440 const MCSymbolData &ResSymData =
441 Assembler.getSymbolData(Symbol.AliasedSymbol());
443 if (Symbol.isVariable()) {
445 if (Symbol.getVariableValue()->EvaluateAsAbsolute(Addr, Layout))
446 coff_symbol->Data.Value = Addr;
449 coff_symbol->Data.Type = (ResSymData.getFlags() & 0x0000FFFF) >> 0;
450 coff_symbol->Data.StorageClass = (ResSymData.getFlags() & 0x00FF0000) >> 16;
452 // If no storage class was specified in the streamer, define it here.
453 if (coff_symbol->Data.StorageClass == 0) {
454 bool external = ResSymData.isExternal() || (ResSymData.Fragment == NULL);
456 coff_symbol->Data.StorageClass =
457 external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC;
460 if (Symbol.isAbsolute() || Symbol.AliasedSymbol().isVariable())
461 coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
462 else if (ResSymData.Fragment != NULL)
463 coff_symbol->Section =
464 SectionMap[&ResSymData.Fragment->getParent()->getSection()];
466 coff_symbol->MCData = &ResSymData;
470 // Maximum offsets for different string table entry encodings.
471 static const unsigned Max6DecimalOffset = 999999;
472 static const unsigned Max7DecimalOffset = 9999999;
473 static const uint64_t MaxBase64Offset = 0xFFFFFFFFFULL; // 64^6, including 0
475 // Encode a string table entry offset in base 64, padded to 6 chars, and
476 // prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
477 // Buffer must be at least 8 bytes large. No terminating null appended.
478 static void encodeBase64StringEntry(char* Buffer, uint64_t Value) {
479 assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
480 "Illegal section name encoding for value");
482 static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
483 "abcdefghijklmnopqrstuvwxyz"
489 char* Ptr = Buffer + 7;
490 for (unsigned i = 0; i < 6; ++i) {
491 unsigned Rem = Value % 64;
493 *(Ptr--) = Alphabet[Rem];
497 /// making a section real involves assigned it a number and putting
498 /// name into the string table if needed
499 void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
500 if (S.Name.size() > COFF::NameSize) {
501 uint64_t StringTableEntry = Strings.insert(S.Name.c_str());
503 if (StringTableEntry <= Max6DecimalOffset) {
504 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
505 } else if (StringTableEntry <= Max7DecimalOffset) {
506 // With seven digits, we have to skip the terminating null. Because
507 // sprintf always appends it, we use a larger temporary buffer.
508 char buffer[9] = { };
509 std::sprintf(buffer, "/%d", unsigned(StringTableEntry));
510 std::memcpy(S.Header.Name, buffer, 8);
511 } else if (StringTableEntry <= MaxBase64Offset) {
512 // Starting with 10,000,000, offsets are encoded as base64.
513 encodeBase64StringEntry(S.Header.Name, StringTableEntry);
515 report_fatal_error("COFF string table is greater than 64 GB.");
518 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
521 S.Symbol->Data.SectionNumber = S.Number;
522 S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
525 void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
526 if (S.Name.size() > COFF::NameSize) {
527 size_t StringTableEntry = Strings.insert(S.Name.c_str());
529 S.set_name_offset(StringTableEntry);
531 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
535 bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
537 // This doesn't seem to be right. Strings referred to from the .data section
538 // need symbols so they can be linked to code in the .text section right?
540 // return Asm.isSymbolLinkerVisible (&SymbolData);
542 // For now, all non-variable symbols are exported,
543 // the linker will sort the rest out for us.
544 return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable();
547 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
548 return (S->Header.Characteristics
549 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
552 //------------------------------------------------------------------------------
553 // entity writing methods
555 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
556 WriteLE16(Header.Machine);
557 WriteLE16(Header.NumberOfSections);
558 WriteLE32(Header.TimeDateStamp);
559 WriteLE32(Header.PointerToSymbolTable);
560 WriteLE32(Header.NumberOfSymbols);
561 WriteLE16(Header.SizeOfOptionalHeader);
562 WriteLE16(Header.Characteristics);
565 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
566 WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
567 WriteLE32(S->Data.Value);
568 WriteLE16(S->Data.SectionNumber);
569 WriteLE16(S->Data.Type);
570 Write8(S->Data.StorageClass);
571 Write8(S->Data.NumberOfAuxSymbols);
572 WriteAuxiliarySymbols(S->Aux);
575 void WinCOFFObjectWriter::WriteAuxiliarySymbols(
576 const COFFSymbol::AuxiliarySymbols &S) {
577 for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
580 case ATFunctionDefinition:
581 WriteLE32(i->Aux.FunctionDefinition.TagIndex);
582 WriteLE32(i->Aux.FunctionDefinition.TotalSize);
583 WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
584 WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
585 WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
587 case ATbfAndefSymbol:
588 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
589 WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
590 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
591 WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
592 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
595 WriteLE32(i->Aux.WeakExternal.TagIndex);
596 WriteLE32(i->Aux.WeakExternal.Characteristics);
597 WriteZeros(sizeof(i->Aux.WeakExternal.unused));
600 WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
601 sizeof(i->Aux.File.FileName)));
603 case ATSectionDefinition:
604 WriteLE32(i->Aux.SectionDefinition.Length);
605 WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
606 WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
607 WriteLE32(i->Aux.SectionDefinition.CheckSum);
608 WriteLE16(i->Aux.SectionDefinition.Number);
609 Write8(i->Aux.SectionDefinition.Selection);
610 WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
616 void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
617 WriteBytes(StringRef(S.Name, COFF::NameSize));
619 WriteLE32(S.VirtualSize);
620 WriteLE32(S.VirtualAddress);
621 WriteLE32(S.SizeOfRawData);
622 WriteLE32(S.PointerToRawData);
623 WriteLE32(S.PointerToRelocations);
624 WriteLE32(S.PointerToLineNumbers);
625 WriteLE16(S.NumberOfRelocations);
626 WriteLE16(S.NumberOfLineNumbers);
627 WriteLE32(S.Characteristics);
630 void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
631 WriteLE32(R.VirtualAddress);
632 WriteLE32(R.SymbolTableIndex);
636 ////////////////////////////////////////////////////////////////////////////////
637 // MCObjectWriter interface implementations
639 void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
640 const MCAsmLayout &Layout) {
641 // "Define" each section & symbol. This creates section & symbol
642 // entries in the staging area.
644 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
647 for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
648 e = Asm.symbol_end();
650 if (ExportSymbol(*i, Asm)) {
651 DefineSymbol(*i, Asm, Layout);
656 void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
657 const MCAsmLayout &Layout,
658 const MCFragment *Fragment,
659 const MCFixup &Fixup,
661 uint64_t &FixedValue) {
662 assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
664 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
665 const MCSymbol &A = Symbol.AliasedSymbol();
666 if (!Asm.hasSymbolData(A))
667 Asm.getContext().FatalError(
669 Twine("symbol '") + A.getName() + "' can not be undefined");
671 MCSymbolData &A_SD = Asm.getSymbolData(A);
673 MCSectionData const *SectionData = Fragment->getParent();
675 // Mark this symbol as requiring an entry in the symbol table.
676 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
677 "Section must already have been defined in ExecutePostLayoutBinding!");
678 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
679 "Symbol must already have been defined in ExecutePostLayoutBinding!");
681 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
682 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
683 const MCSymbolRefExpr *SymB = Target.getSymB();
684 bool CrossSection = false;
687 const MCSymbol *B = &SymB->getSymbol();
688 MCSymbolData &B_SD = Asm.getSymbolData(*B);
689 if (!B_SD.getFragment())
690 Asm.getContext().FatalError(
692 Twine("symbol '") + B->getName() +
693 "' can not be undefined in a subtraction expression");
695 if (!A_SD.getFragment())
696 Asm.getContext().FatalError(
698 Twine("symbol '") + Symbol.getName() +
699 "' can not be undefined in a subtraction expression");
701 CrossSection = &Symbol.getSection() != &B->getSection();
703 // Offset of the symbol in the section
704 int64_t a = Layout.getSymbolOffset(&B_SD);
706 // Ofeset of the relocation in the section
707 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
710 // In the case where we have SymbA and SymB, we just need to store the delta
711 // between the two symbols. Update FixedValue to account for the delta, and
712 // skip recording the relocation.
716 FixedValue = Target.getConstant();
719 COFFRelocation Reloc;
721 Reloc.Data.SymbolTableIndex = 0;
722 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
724 // Turn relocations for temporary symbols into section relocations.
725 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
726 Reloc.Symb = coff_symbol->Section->Symbol;
727 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
728 + coff_symbol->MCData->getOffset();
730 Reloc.Symb = coff_symbol;
732 ++Reloc.Symb->Relocations;
734 Reloc.Data.VirtualAddress += Fixup.getOffset();
735 Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup,
738 // FIXME: Can anyone explain what this does other than adjust for the size
740 if (Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32 ||
741 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32)
744 coff_section->Relocations.push_back(Reloc);
747 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
748 const MCAsmLayout &Layout) {
749 // Assign symbol and section indexes and offsets.
750 Header.NumberOfSections = 0;
752 DenseMap<COFFSection *, uint16_t> SectionIndices;
753 for (sections::iterator i = Sections.begin(),
754 e = Sections.end(); i != e; i++) {
755 if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
756 size_t Number = ++Header.NumberOfSections;
757 SectionIndices[*i] = Number;
758 MakeSectionReal(**i, Number);
764 Header.NumberOfSymbols = 0;
766 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
767 COFFSymbol *coff_symbol = *i;
768 MCSymbolData const *SymbolData = coff_symbol->MCData;
770 // Update section number & offset for symbols that have them.
771 if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
772 assert(coff_symbol->Section != NULL);
774 coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
775 coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
776 + SymbolData->Offset;
779 if (coff_symbol->should_keep()) {
780 MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
782 // Update auxiliary symbol info.
783 coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
784 Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
786 coff_symbol->Index = -1;
789 // Fixup weak external references.
790 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
791 COFFSymbol *coff_symbol = *i;
792 if (coff_symbol->Other != NULL) {
793 assert(coff_symbol->Index != -1);
794 assert(coff_symbol->Aux.size() == 1 &&
795 "Symbol must contain one aux symbol!");
796 assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
797 "Symbol's aux symbol must be a Weak External!");
798 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
802 // Fixup associative COMDAT sections.
803 for (sections::iterator i = Sections.begin(),
804 e = Sections.end(); i != e; i++) {
805 if ((*i)->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
806 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
809 const MCSectionCOFF &MCSec = static_cast<const MCSectionCOFF &>(
810 (*i)->MCData->getSection());
812 COFFSection *Assoc = SectionMap.lookup(MCSec.getAssocSection());
814 report_fatal_error(Twine("Missing associated COMDAT section ") +
815 MCSec.getAssocSection()->getSectionName() +
816 " for section " + MCSec.getSectionName());
819 // Skip this section if the associated section is unused.
820 if (Assoc->Number == -1)
823 (*i)->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
827 // Assign file offsets to COFF object file structures.
831 offset += COFF::HeaderSize;
832 offset += COFF::SectionSize * Header.NumberOfSections;
834 for (MCAssembler::const_iterator i = Asm.begin(),
837 COFFSection *Sec = SectionMap[&i->getSection()];
839 if (Sec->Number == -1)
842 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);
844 if (IsPhysicalSection(Sec)) {
845 Sec->Header.PointerToRawData = offset;
847 offset += Sec->Header.SizeOfRawData;
850 if (Sec->Relocations.size() > 0) {
851 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
853 if (RelocationsOverflow) {
854 // Signal overflow by setting NumberOfSections to max value. Actual
855 // size is found in reloc #0. Microsoft tools understand this.
856 Sec->Header.NumberOfRelocations = 0xffff;
858 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
860 Sec->Header.PointerToRelocations = offset;
862 if (RelocationsOverflow) {
863 // Reloc #0 will contain actual count, so make room for it.
864 offset += COFF::RelocationSize;
867 offset += COFF::RelocationSize * Sec->Relocations.size();
869 for (relocations::iterator cr = Sec->Relocations.begin(),
870 er = Sec->Relocations.end();
872 assert((*cr).Symb->Index != -1);
873 (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
877 assert(Sec->Symbol->Aux.size() == 1
878 && "Section's symbol must have one aux!");
879 AuxSymbol &Aux = Sec->Symbol->Aux[0];
880 assert(Aux.AuxType == ATSectionDefinition &&
881 "Section's symbol's aux symbol must be a Section Definition!");
882 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
883 Aux.Aux.SectionDefinition.NumberOfRelocations =
884 Sec->Header.NumberOfRelocations;
885 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
886 Sec->Header.NumberOfLineNumbers;
889 Header.PointerToSymbolTable = offset;
891 // We want a deterministic output. It looks like GNU as also writes 0 in here.
892 Header.TimeDateStamp = 0;
894 // Write it all to disk...
895 WriteFileHeader(Header);
898 sections::iterator i, ie;
899 MCAssembler::const_iterator j, je;
901 for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
902 if ((*i)->Number != -1) {
903 if ((*i)->Relocations.size() >= 0xffff) {
904 (*i)->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
906 WriteSectionHeader((*i)->Header);
909 for (i = Sections.begin(), ie = Sections.end(),
910 j = Asm.begin(), je = Asm.end();
911 (i != ie) && (j != je); ++i, ++j) {
913 if ((*i)->Number == -1)
916 if ((*i)->Header.PointerToRawData != 0) {
917 assert(OS.tell() == (*i)->Header.PointerToRawData &&
918 "Section::PointerToRawData is insane!");
920 Asm.writeSectionData(j, Layout);
923 if ((*i)->Relocations.size() > 0) {
924 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
925 "Section::PointerToRelocations is insane!");
927 if ((*i)->Relocations.size() >= 0xffff) {
928 // In case of overflow, write actual relocation count as first
929 // relocation. Including the synthetic reloc itself (+ 1).
931 r.VirtualAddress = (*i)->Relocations.size() + 1;
932 r.SymbolTableIndex = 0;
937 for (relocations::const_iterator k = (*i)->Relocations.begin(),
938 ke = (*i)->Relocations.end();
940 WriteRelocation(k->Data);
943 assert((*i)->Header.PointerToRelocations == 0 &&
944 "Section::PointerToRelocations is insane!");
948 assert(OS.tell() == Header.PointerToSymbolTable &&
949 "Header::PointerToSymbolTable is insane!");
951 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
952 if ((*i)->Index != -1)
955 OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
958 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :
962 // Pin the vtable to this file.
963 void MCWinCOFFObjectTargetWriter::anchor() {}
965 //------------------------------------------------------------------------------
966 // WinCOFFObjectWriter factory function
969 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
971 return new WinCOFFObjectWriter(MOTW, OS);