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 #include "llvm/MC/MCWinCOFFObjectWriter.h"
15 #include "llvm/ADT/DenseMap.h"
16 #include "llvm/ADT/StringMap.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/Twine.h"
20 #include "llvm/MC/MCAsmLayout.h"
21 #include "llvm/MC/MCAssembler.h"
22 #include "llvm/MC/MCContext.h"
23 #include "llvm/MC/MCExpr.h"
24 #include "llvm/MC/MCObjectWriter.h"
25 #include "llvm/MC/MCSection.h"
26 #include "llvm/MC/MCSectionCOFF.h"
27 #include "llvm/MC/MCSymbol.h"
28 #include "llvm/MC/MCValue.h"
29 #include "llvm/Support/COFF.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/Endian.h"
32 #include "llvm/Support/ErrorHandling.h"
33 #include "llvm/Support/TimeValue.h"
38 #define DEBUG_TYPE "WinCOFFObjectWriter"
41 typedef SmallString<COFF::NameSize> name;
52 AuxiliaryType AuxType;
63 typedef SmallVector<AuxSymbol, 1> AuxiliarySymbols;
72 MCSymbolData const *MCData;
74 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(nullptr) {}
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);
124 class WinCOFFObjectWriter : public MCObjectWriter {
127 typedef std::vector<std::unique_ptr<COFFSymbol>> symbols;
128 typedef std::vector<std::unique_ptr<COFFSection>> sections;
130 typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map;
131 typedef DenseMap<MCSection const *, COFFSection *> section_map;
133 std::unique_ptr<MCWinCOFFObjectTargetWriter> TargetObjectWriter;
135 // Root level file contents.
141 // Maps used during object file creation.
142 section_map SectionMap;
143 symbol_map SymbolMap;
147 WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, raw_ostream &OS);
149 void reset() override {
150 memset(&Header, 0, sizeof(Header));
151 Header.Machine = TargetObjectWriter->getMachine();
157 MCObjectWriter::reset();
160 COFFSymbol *createSymbol(StringRef Name);
161 COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol);
162 COFFSection *createSection(StringRef Name);
164 template <typename object_t, typename list_t>
165 object_t *createCOFFEntity(StringRef Name, list_t &List);
167 void DefineSection(MCSectionData const &SectionData);
168 void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler,
169 const MCAsmLayout &Layout);
171 void MakeSymbolReal(COFFSymbol &S, size_t Index);
172 void MakeSectionReal(COFFSection &S, size_t Number);
174 bool ExportSymbol(const MCSymbol &Symbol, MCAssembler &Asm);
176 bool IsPhysicalSection(COFFSection *S);
178 // Entity writing methods.
180 void WriteFileHeader(const COFF::header &Header);
181 void WriteSymbol(const COFFSymbol &S);
182 void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
183 void WriteSectionHeader(const COFF::section &S);
184 void WriteRelocation(const COFF::relocation &R);
186 // MCObjectWriter interface implementation.
188 void ExecutePostLayoutBinding(MCAssembler &Asm,
189 const MCAsmLayout &Layout) override;
191 void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
192 const MCFragment *Fragment, const MCFixup &Fixup,
193 MCValue Target, bool &IsPCRel,
194 uint64_t &FixedValue) override;
196 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
200 static inline void write_uint32_le(void *Data, uint32_t Value) {
201 support::endian::write<uint32_t, support::little, support::unaligned>(Data,
205 //------------------------------------------------------------------------------
206 // Symbol class implementation
208 COFFSymbol::COFFSymbol(StringRef name)
209 : Name(name.begin(), name.end())
214 memset(&Data, 0, sizeof(Data));
217 // In the case that the name does not fit within 8 bytes, the offset
218 // into the string table is stored in the last 4 bytes instead, leaving
219 // the first 4 bytes as 0.
220 void COFFSymbol::set_name_offset(uint32_t Offset) {
221 write_uint32_le(Data.Name + 0, 0);
222 write_uint32_le(Data.Name + 4, Offset);
225 /// logic to decide if the symbol should be reported in the symbol table
226 bool COFFSymbol::should_keep() const {
227 // no section means its external, keep it
231 // if it has relocations pointing at it, keep it
232 if (Relocations > 0) {
233 assert(Section->Number != -1 && "Sections with relocations must be real!");
237 // if the section its in is being droped, drop it
238 if (Section->Number == -1)
241 // if it is the section symbol, keep it
242 if (Section->Symbol == this)
245 // if its temporary, drop it
246 if (MCData && MCData->getSymbol().isTemporary())
249 // otherwise, keep it
253 //------------------------------------------------------------------------------
254 // Section class implementation
256 COFFSection::COFFSection(StringRef name)
260 memset(&Header, 0, sizeof(Header));
263 size_t COFFSection::size() {
264 return COFF::SectionSize;
267 //------------------------------------------------------------------------------
268 // StringTable class implementation
270 /// Write the length of the string table into Data.
271 /// The length of the string table includes uint32 length header.
272 void StringTable::update_length() {
273 write_uint32_le(&Data.front(), Data.size());
276 StringTable::StringTable() {
277 // The string table data begins with the length of the entire string table
278 // including the length header. Allocate space for this header.
283 size_t StringTable::size() const {
287 /// Add String to the table iff it is not already there.
288 /// @returns the index into the string table where the string is now located.
289 size_t StringTable::insert(StringRef String) {
290 map::iterator i = Map.find(String);
295 size_t Offset = Data.size();
297 // Insert string data into string table.
298 Data.insert(Data.end(), String.begin(), String.end());
299 Data.push_back('\0');
301 // Put a reference to it in the map.
302 Map[String] = Offset;
304 // Update the internal length field.
310 //------------------------------------------------------------------------------
311 // WinCOFFObjectWriter class implementation
313 WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
315 : MCObjectWriter(OS, true), TargetObjectWriter(MOTW) {
316 memset(&Header, 0, sizeof(Header));
318 Header.Machine = TargetObjectWriter->getMachine();
321 COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
322 return createCOFFEntity<COFFSymbol>(Name, Symbols);
325 COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
326 symbol_map::iterator i = SymbolMap.find(Symbol);
327 if (i != SymbolMap.end())
329 COFFSymbol *RetSymbol
330 = createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
331 SymbolMap[Symbol] = RetSymbol;
335 COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) {
336 return createCOFFEntity<COFFSection>(Name, Sections);
339 /// A template used to lookup or create a symbol/section, and initialize it if
341 template <typename object_t, typename list_t>
342 object_t *WinCOFFObjectWriter::createCOFFEntity(StringRef Name,
344 List.push_back(make_unique<object_t>(Name));
346 return List.back().get();
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());
360 if (Sec.getSelection() != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
361 if (const MCSymbol *S = Sec.getCOMDATSymbol()) {
362 COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(S);
363 if (COMDATSymbol->Section)
364 report_fatal_error("two sections have the same comdat");
365 COMDATSymbol->Section = coff_section;
369 coff_section->Symbol = coff_symbol;
370 coff_symbol->Section = coff_section;
371 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
373 // In this case the auxiliary symbol is a Section Definition.
374 coff_symbol->Aux.resize(1);
375 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
376 coff_symbol->Aux[0].AuxType = ATSectionDefinition;
377 coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
379 coff_section->Header.Characteristics = Sec.getCharacteristics();
381 uint32_t &Characteristics = coff_section->Header.Characteristics;
382 switch (SectionData.getAlignment()) {
383 case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break;
384 case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break;
385 case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break;
386 case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break;
387 case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break;
388 case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break;
389 case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break;
390 case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break;
391 case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break;
392 case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break;
393 case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
394 case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
395 case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
396 case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
398 llvm_unreachable("unsupported section alignment");
401 // Bind internal COFF section to MC section.
402 coff_section->MCData = &SectionData;
403 SectionMap[&SectionData.getSection()] = coff_section;
406 static uint64_t getSymbolValue(const MCSymbolData &Data,
407 const MCAsmLayout &Layout) {
408 if (Data.isCommon() && Data.isExternal())
409 return Data.getCommonSize();
412 if (!Layout.getSymbolOffset(&Data, Res))
418 /// This function takes a symbol data object from the assembler
419 /// and creates the associated COFF symbol staging object.
420 void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
421 MCAssembler &Assembler,
422 const MCAsmLayout &Layout) {
423 MCSymbol const &Symbol = SymbolData.getSymbol();
424 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol);
425 SymbolMap[&Symbol] = coff_symbol;
427 if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
428 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
430 if (Symbol.isVariable()) {
431 const MCSymbolRefExpr *SymRef =
432 dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue());
435 report_fatal_error("Weak externals may only alias symbols");
437 coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol());
439 std::string WeakName = std::string(".weak.")
440 + Symbol.getName().str()
442 COFFSymbol *WeakDefault = createSymbol(WeakName);
443 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
444 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
445 WeakDefault->Data.Type = 0;
446 WeakDefault->Data.Value = 0;
447 coff_symbol->Other = WeakDefault;
450 // Setup the Weak External auxiliary symbol.
451 coff_symbol->Aux.resize(1);
452 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
453 coff_symbol->Aux[0].AuxType = ATWeakExternal;
454 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
455 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
456 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
458 coff_symbol->MCData = &SymbolData;
460 const MCSymbolData &ResSymData = Assembler.getSymbolData(Symbol);
461 const MCSymbol *Base = Layout.getBaseSymbol(Symbol);
462 coff_symbol->Data.Value = getSymbolValue(ResSymData, Layout);
464 coff_symbol->Data.Type = (ResSymData.getFlags() & 0x0000FFFF) >> 0;
465 coff_symbol->Data.StorageClass = (ResSymData.getFlags() & 0x00FF0000) >> 16;
467 // If no storage class was specified in the streamer, define it here.
468 if (coff_symbol->Data.StorageClass == 0) {
470 ResSymData.isExternal() ||
471 (!ResSymData.getFragment() && !ResSymData.getSymbol().isVariable());
473 coff_symbol->Data.StorageClass = IsExternal
474 ? COFF::IMAGE_SYM_CLASS_EXTERNAL
475 : COFF::IMAGE_SYM_CLASS_STATIC;
479 coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
481 const MCSymbolData &BaseData = Assembler.getSymbolData(*Base);
482 if (BaseData.Fragment) {
484 SectionMap[&BaseData.Fragment->getParent()->getSection()];
486 if (coff_symbol->Section && coff_symbol->Section != Sec)
487 report_fatal_error("conflicting sections for symbol");
489 coff_symbol->Section = Sec;
493 coff_symbol->MCData = &ResSymData;
497 // Maximum offsets for different string table entry encodings.
498 static const unsigned Max6DecimalOffset = 999999;
499 static const unsigned Max7DecimalOffset = 9999999;
500 static const uint64_t MaxBase64Offset = 0xFFFFFFFFFULL; // 64^6, including 0
502 // Encode a string table entry offset in base 64, padded to 6 chars, and
503 // prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
504 // Buffer must be at least 8 bytes large. No terminating null appended.
505 static void encodeBase64StringEntry(char* Buffer, uint64_t Value) {
506 assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
507 "Illegal section name encoding for value");
509 static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
510 "abcdefghijklmnopqrstuvwxyz"
516 char* Ptr = Buffer + 7;
517 for (unsigned i = 0; i < 6; ++i) {
518 unsigned Rem = Value % 64;
520 *(Ptr--) = Alphabet[Rem];
524 /// making a section real involves assigned it a number and putting
525 /// name into the string table if needed
526 void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
527 if (S.Name.size() > COFF::NameSize) {
528 uint64_t StringTableEntry = Strings.insert(S.Name.c_str());
530 if (StringTableEntry <= Max6DecimalOffset) {
531 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
532 } else if (StringTableEntry <= Max7DecimalOffset) {
533 // With seven digits, we have to skip the terminating null. Because
534 // sprintf always appends it, we use a larger temporary buffer.
535 char buffer[9] = { };
536 std::sprintf(buffer, "/%d", unsigned(StringTableEntry));
537 std::memcpy(S.Header.Name, buffer, 8);
538 } else if (StringTableEntry <= MaxBase64Offset) {
539 // Starting with 10,000,000, offsets are encoded as base64.
540 encodeBase64StringEntry(S.Header.Name, StringTableEntry);
542 report_fatal_error("COFF string table is greater than 64 GB.");
545 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
548 S.Symbol->Data.SectionNumber = S.Number;
549 S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
552 void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
553 if (S.Name.size() > COFF::NameSize) {
554 size_t StringTableEntry = Strings.insert(S.Name.c_str());
556 S.set_name_offset(StringTableEntry);
558 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
562 bool WinCOFFObjectWriter::ExportSymbol(const MCSymbol &Symbol,
564 // This doesn't seem to be right. Strings referred to from the .data section
565 // need symbols so they can be linked to code in the .text section right?
567 // return Asm.isSymbolLinkerVisible(Symbol);
569 // Non-temporary labels should always be visible to the linker.
570 if (!Symbol.isTemporary())
573 // Absolute temporary labels are never visible.
574 if (!Symbol.isInSection())
577 // For now, all non-variable symbols are exported,
578 // the linker will sort the rest out for us.
579 return !Symbol.isVariable();
582 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
583 return (S->Header.Characteristics
584 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
587 //------------------------------------------------------------------------------
588 // entity writing methods
590 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
592 WriteLE16(COFF::IMAGE_FILE_MACHINE_UNKNOWN);
594 WriteLE16(COFF::BigObjHeader::MinBigObjectVersion);
595 WriteLE16(Header.Machine);
596 WriteLE32(Header.TimeDateStamp);
597 for (uint8_t MagicChar : COFF::BigObjMagic)
603 WriteLE32(Header.NumberOfSections);
604 WriteLE32(Header.PointerToSymbolTable);
605 WriteLE32(Header.NumberOfSymbols);
607 WriteLE16(Header.Machine);
608 WriteLE16(static_cast<int16_t>(Header.NumberOfSections));
609 WriteLE32(Header.TimeDateStamp);
610 WriteLE32(Header.PointerToSymbolTable);
611 WriteLE32(Header.NumberOfSymbols);
612 WriteLE16(Header.SizeOfOptionalHeader);
613 WriteLE16(Header.Characteristics);
617 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol &S) {
618 WriteBytes(StringRef(S.Data.Name, COFF::NameSize));
619 WriteLE32(S.Data.Value);
621 WriteLE32(S.Data.SectionNumber);
623 WriteLE16(static_cast<int16_t>(S.Data.SectionNumber));
624 WriteLE16(S.Data.Type);
625 Write8(S.Data.StorageClass);
626 Write8(S.Data.NumberOfAuxSymbols);
627 WriteAuxiliarySymbols(S.Aux);
630 void WinCOFFObjectWriter::WriteAuxiliarySymbols(
631 const COFFSymbol::AuxiliarySymbols &S) {
632 for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
635 case ATFunctionDefinition:
636 WriteLE32(i->Aux.FunctionDefinition.TagIndex);
637 WriteLE32(i->Aux.FunctionDefinition.TotalSize);
638 WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
639 WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
640 WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
642 WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
644 case ATbfAndefSymbol:
645 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
646 WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
647 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
648 WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
649 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
651 WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
654 WriteLE32(i->Aux.WeakExternal.TagIndex);
655 WriteLE32(i->Aux.WeakExternal.Characteristics);
656 WriteZeros(sizeof(i->Aux.WeakExternal.unused));
658 WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
662 StringRef(reinterpret_cast<const char *>(&i->Aux),
663 UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size));
665 case ATSectionDefinition:
666 WriteLE32(i->Aux.SectionDefinition.Length);
667 WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
668 WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
669 WriteLE32(i->Aux.SectionDefinition.CheckSum);
670 WriteLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number));
671 Write8(i->Aux.SectionDefinition.Selection);
672 WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
673 WriteLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number >> 16));
675 WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
681 void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
682 WriteBytes(StringRef(S.Name, COFF::NameSize));
684 WriteLE32(S.VirtualSize);
685 WriteLE32(S.VirtualAddress);
686 WriteLE32(S.SizeOfRawData);
687 WriteLE32(S.PointerToRawData);
688 WriteLE32(S.PointerToRelocations);
689 WriteLE32(S.PointerToLineNumbers);
690 WriteLE16(S.NumberOfRelocations);
691 WriteLE16(S.NumberOfLineNumbers);
692 WriteLE32(S.Characteristics);
695 void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
696 WriteLE32(R.VirtualAddress);
697 WriteLE32(R.SymbolTableIndex);
701 ////////////////////////////////////////////////////////////////////////////////
702 // MCObjectWriter interface implementations
704 void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
705 const MCAsmLayout &Layout) {
706 // "Define" each section & symbol. This creates section & symbol
707 // entries in the staging area.
708 for (const auto & Section : Asm)
709 DefineSection(Section);
711 for (MCSymbolData &SD : Asm.symbols())
712 if (ExportSymbol(SD.getSymbol(), Asm))
713 DefineSymbol(SD, Asm, Layout);
716 void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
717 const MCAsmLayout &Layout,
718 const MCFragment *Fragment,
719 const MCFixup &Fixup,
722 uint64_t &FixedValue) {
723 assert(Target.getSymA() && "Relocation must reference a symbol!");
725 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
726 const MCSymbol &A = Symbol.AliasedSymbol();
727 if (!Asm.hasSymbolData(A))
728 Asm.getContext().FatalError(
730 Twine("symbol '") + A.getName() + "' can not be undefined");
732 const MCSymbolData &A_SD = Asm.getSymbolData(A);
734 MCSectionData const *SectionData = Fragment->getParent();
736 // Mark this symbol as requiring an entry in the symbol table.
737 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
738 "Section must already have been defined in ExecutePostLayoutBinding!");
739 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
740 "Symbol must already have been defined in ExecutePostLayoutBinding!");
742 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
743 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
744 const MCSymbolRefExpr *SymB = Target.getSymB();
745 bool CrossSection = false;
748 const MCSymbol *B = &SymB->getSymbol();
749 const MCSymbolData &B_SD = Asm.getSymbolData(*B);
750 if (!B_SD.getFragment())
751 Asm.getContext().FatalError(
753 Twine("symbol '") + B->getName() +
754 "' can not be undefined in a subtraction expression");
756 if (!A_SD.getFragment())
757 Asm.getContext().FatalError(
759 Twine("symbol '") + Symbol.getName() +
760 "' can not be undefined in a subtraction expression");
762 CrossSection = &Symbol.getSection() != &B->getSection();
764 // Offset of the symbol in the section
765 int64_t a = Layout.getSymbolOffset(&B_SD);
767 // Ofeset of the relocation in the section
768 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
771 // In the case where we have SymbA and SymB, we just need to store the delta
772 // between the two symbols. Update FixedValue to account for the delta, and
773 // skip recording the relocation.
777 FixedValue = Target.getConstant();
780 COFFRelocation Reloc;
782 Reloc.Data.SymbolTableIndex = 0;
783 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
785 // Turn relocations for temporary symbols into section relocations.
786 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
787 Reloc.Symb = coff_symbol->Section->Symbol;
788 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
789 + coff_symbol->MCData->getOffset();
791 Reloc.Symb = coff_symbol;
793 ++Reloc.Symb->Relocations;
795 Reloc.Data.VirtualAddress += Fixup.getOffset();
796 Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup,
799 // FIXME: Can anyone explain what this does other than adjust for the size
801 if ((Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64 &&
802 Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32) ||
803 (Header.Machine == COFF::IMAGE_FILE_MACHINE_I386 &&
804 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32))
807 if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) {
808 switch (Reloc.Data.Type) {
809 case COFF::IMAGE_REL_ARM_ABSOLUTE:
810 case COFF::IMAGE_REL_ARM_ADDR32:
811 case COFF::IMAGE_REL_ARM_ADDR32NB:
812 case COFF::IMAGE_REL_ARM_TOKEN:
813 case COFF::IMAGE_REL_ARM_SECTION:
814 case COFF::IMAGE_REL_ARM_SECREL:
816 case COFF::IMAGE_REL_ARM_BRANCH11:
817 case COFF::IMAGE_REL_ARM_BLX11:
818 // IMAGE_REL_ARM_BRANCH11 and IMAGE_REL_ARM_BLX11 are only used for
819 // pre-ARMv7, which implicitly rules it out of ARMNT (it would be valid
821 case COFF::IMAGE_REL_ARM_BRANCH24:
822 case COFF::IMAGE_REL_ARM_BLX24:
823 case COFF::IMAGE_REL_ARM_MOV32A:
824 // IMAGE_REL_ARM_BRANCH24, IMAGE_REL_ARM_BLX24, IMAGE_REL_ARM_MOV32A are
825 // only used for ARM mode code, which is documented as being unsupported
826 // by Windows on ARM. Empirical proof indicates that masm is able to
827 // generate the relocations however the rest of the MSVC toolchain is
828 // unable to handle it.
829 llvm_unreachable("unsupported relocation");
831 case COFF::IMAGE_REL_ARM_MOV32T:
833 case COFF::IMAGE_REL_ARM_BRANCH20T:
834 case COFF::IMAGE_REL_ARM_BRANCH24T:
835 case COFF::IMAGE_REL_ARM_BLX23T:
836 // IMAGE_REL_BRANCH20T, IMAGE_REL_ARM_BRANCH24T, IMAGE_REL_ARM_BLX23T all
837 // perform a 4 byte adjustment to the relocation. Relative branches are
838 // offset by 4 on ARM, however, because there is no RELA relocations, all
839 // branches are offset by 4.
840 FixedValue = FixedValue + 4;
845 if (TargetObjectWriter->recordRelocation(Fixup))
846 coff_section->Relocations.push_back(Reloc);
849 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
850 const MCAsmLayout &Layout) {
851 size_t SectionsSize = Sections.size();
852 if (SectionsSize > static_cast<size_t>(INT32_MAX))
854 "PE COFF object files can't have more than 2147483647 sections");
856 // Assign symbol and section indexes and offsets.
857 int32_t NumberOfSections = static_cast<int32_t>(SectionsSize);
859 UseBigObj = NumberOfSections > COFF::MaxNumberOfSections16;
861 DenseMap<COFFSection *, int32_t> SectionIndices(
862 NextPowerOf2(NumberOfSections));
864 for (const auto &Section : Sections) {
865 SectionIndices[Section.get()] = Number;
866 MakeSectionReal(*Section, Number);
870 Header.NumberOfSections = NumberOfSections;
871 Header.NumberOfSymbols = 0;
873 for (auto FI = Asm.file_names_begin(), FE = Asm.file_names_end();
875 // round up to calculate the number of auxiliary symbols required
876 unsigned SymbolSize = UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size;
877 unsigned Count = (FI->size() + SymbolSize - 1) / SymbolSize;
879 COFFSymbol *file = createSymbol(".file");
880 file->Data.SectionNumber = COFF::IMAGE_SYM_DEBUG;
881 file->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE;
882 file->Aux.resize(Count);
885 unsigned Length = FI->size();
886 for (auto & Aux : file->Aux) {
887 Aux.AuxType = ATFile;
889 if (Length > SymbolSize) {
890 memcpy(&Aux.Aux, FI->c_str() + Offset, SymbolSize);
891 Length = Length - SymbolSize;
893 memcpy(&Aux.Aux, FI->c_str() + Offset, Length);
894 memset((char *)&Aux.Aux + Length, 0, SymbolSize - Length);
898 Offset += SymbolSize;
902 for (auto &Symbol : Symbols) {
903 // Update section number & offset for symbols that have them.
905 Symbol->Data.SectionNumber = Symbol->Section->Number;
907 if (Symbol->should_keep()) {
908 MakeSymbolReal(*Symbol, Header.NumberOfSymbols++);
910 // Update auxiliary symbol info.
911 Symbol->Data.NumberOfAuxSymbols = Symbol->Aux.size();
912 Header.NumberOfSymbols += Symbol->Data.NumberOfAuxSymbols;
917 // Fixup weak external references.
918 for (auto & Symbol : Symbols) {
920 assert(Symbol->Index != -1);
921 assert(Symbol->Aux.size() == 1 && "Symbol must contain one aux symbol!");
922 assert(Symbol->Aux[0].AuxType == ATWeakExternal &&
923 "Symbol's aux symbol must be a Weak External!");
924 Symbol->Aux[0].Aux.WeakExternal.TagIndex = Symbol->Other->Index;
928 // Fixup associative COMDAT sections.
929 for (auto & Section : Sections) {
930 if (Section->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
931 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
934 const MCSectionCOFF &MCSec =
935 static_cast<const MCSectionCOFF &>(Section->MCData->getSection());
937 const MCSymbol *COMDAT = MCSec.getCOMDATSymbol();
939 COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(COMDAT);
940 assert(COMDATSymbol);
941 COFFSection *Assoc = COMDATSymbol->Section;
944 Twine("Missing associated COMDAT section for section ") +
945 MCSec.getSectionName());
947 // Skip this section if the associated section is unused.
948 if (Assoc->Number == -1)
951 Section->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
955 // Assign file offsets to COFF object file structures.
960 offset += COFF::Header32Size;
962 offset += COFF::Header16Size;
963 offset += COFF::SectionSize * Header.NumberOfSections;
965 for (const auto & Section : Asm) {
966 COFFSection *Sec = SectionMap[&Section.getSection()];
968 if (Sec->Number == -1)
971 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(&Section);
973 if (IsPhysicalSection(Sec)) {
974 Sec->Header.PointerToRawData = offset;
976 offset += Sec->Header.SizeOfRawData;
979 if (Sec->Relocations.size() > 0) {
980 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
982 if (RelocationsOverflow) {
983 // Signal overflow by setting NumberOfRelocations to max value. Actual
984 // size is found in reloc #0. Microsoft tools understand this.
985 Sec->Header.NumberOfRelocations = 0xffff;
987 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
989 Sec->Header.PointerToRelocations = offset;
991 if (RelocationsOverflow) {
992 // Reloc #0 will contain actual count, so make room for it.
993 offset += COFF::RelocationSize;
996 offset += COFF::RelocationSize * Sec->Relocations.size();
998 for (auto & Relocation : Sec->Relocations) {
999 assert(Relocation.Symb->Index != -1);
1000 Relocation.Data.SymbolTableIndex = Relocation.Symb->Index;
1004 assert(Sec->Symbol->Aux.size() == 1 &&
1005 "Section's symbol must have one aux!");
1006 AuxSymbol &Aux = Sec->Symbol->Aux[0];
1007 assert(Aux.AuxType == ATSectionDefinition &&
1008 "Section's symbol's aux symbol must be a Section Definition!");
1009 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
1010 Aux.Aux.SectionDefinition.NumberOfRelocations =
1011 Sec->Header.NumberOfRelocations;
1012 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
1013 Sec->Header.NumberOfLineNumbers;
1016 Header.PointerToSymbolTable = offset;
1018 // We want a deterministic output. It looks like GNU as also writes 0 in here.
1019 Header.TimeDateStamp = 0;
1021 // Write it all to disk...
1022 WriteFileHeader(Header);
1025 sections::iterator i, ie;
1026 MCAssembler::const_iterator j, je;
1028 for (auto & Section : Sections) {
1029 if (Section->Number != -1) {
1030 if (Section->Relocations.size() >= 0xffff)
1031 Section->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
1032 WriteSectionHeader(Section->Header);
1036 for (i = Sections.begin(), ie = Sections.end(),
1037 j = Asm.begin(), je = Asm.end();
1038 (i != ie) && (j != je); ++i, ++j) {
1040 if ((*i)->Number == -1)
1043 if ((*i)->Header.PointerToRawData != 0) {
1044 assert(OS.tell() == (*i)->Header.PointerToRawData &&
1045 "Section::PointerToRawData is insane!");
1047 Asm.writeSectionData(j, Layout);
1050 if ((*i)->Relocations.size() > 0) {
1051 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
1052 "Section::PointerToRelocations is insane!");
1054 if ((*i)->Relocations.size() >= 0xffff) {
1055 // In case of overflow, write actual relocation count as first
1056 // relocation. Including the synthetic reloc itself (+ 1).
1058 r.VirtualAddress = (*i)->Relocations.size() + 1;
1059 r.SymbolTableIndex = 0;
1064 for (const auto & Relocation : (*i)->Relocations)
1065 WriteRelocation(Relocation.Data);
1067 assert((*i)->Header.PointerToRelocations == 0 &&
1068 "Section::PointerToRelocations is insane!");
1072 assert(OS.tell() == Header.PointerToSymbolTable &&
1073 "Header::PointerToSymbolTable is insane!");
1075 for (auto & Symbol : Symbols)
1076 if (Symbol->Index != -1)
1077 WriteSymbol(*Symbol);
1079 OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
1082 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :
1086 // Pin the vtable to this file.
1087 void MCWinCOFFObjectTargetWriter::anchor() {}
1089 //------------------------------------------------------------------------------
1090 // WinCOFFObjectWriter factory function
1093 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
1095 return new WinCOFFObjectWriter(MOTW, OS);