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/MC/StringTableBuilder.h"
30 #include "llvm/Support/COFF.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Support/Endian.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/TimeValue.h"
39 #define DEBUG_TYPE "WinCOFFObjectWriter"
42 typedef SmallString<COFF::NameSize> name;
53 AuxiliaryType AuxType;
64 typedef SmallVector<AuxSymbol, 1> AuxiliarySymbols;
73 MCSymbolData const *MCData;
75 COFFSymbol(StringRef name);
76 void set_name_offset(uint32_t Offset);
78 bool should_keep() const;
81 // This class contains staging data for a COFF relocation entry.
82 struct COFFRelocation {
83 COFF::relocation Data;
86 COFFRelocation() : Symb(nullptr) {}
87 static size_t size() { return COFF::RelocationSize; }
90 typedef std::vector<COFFRelocation> relocations;
98 MCSectionData const *MCData;
100 relocations Relocations;
102 COFFSection(StringRef name);
103 static size_t size();
106 class WinCOFFObjectWriter : public MCObjectWriter {
109 typedef std::vector<std::unique_ptr<COFFSymbol>> symbols;
110 typedef std::vector<std::unique_ptr<COFFSection>> sections;
112 typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map;
113 typedef DenseMap<MCSection const *, COFFSection *> section_map;
115 std::unique_ptr<MCWinCOFFObjectTargetWriter> TargetObjectWriter;
117 // Root level file contents.
121 StringTableBuilder Strings;
123 // Maps used during object file creation.
124 section_map SectionMap;
125 symbol_map SymbolMap;
129 WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, raw_ostream &OS);
131 void reset() override {
132 memset(&Header, 0, sizeof(Header));
133 Header.Machine = TargetObjectWriter->getMachine();
139 MCObjectWriter::reset();
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 SetSymbolName(COFFSymbol &S);
154 void SetSectionName(COFFSection &S);
156 bool ExportSymbol(const MCSymbol &Symbol, 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 Value) {
183 support::endian::write<uint32_t, support::little, support::unaligned>(Data,
187 //------------------------------------------------------------------------------
188 // Symbol class implementation
190 COFFSymbol::COFFSymbol(StringRef name)
191 : Name(name.begin(), name.end())
196 memset(&Data, 0, sizeof(Data));
199 // In the case that the name does not fit within 8 bytes, the offset
200 // into the string table is stored in the last 4 bytes instead, leaving
201 // the first 4 bytes as 0.
202 void COFFSymbol::set_name_offset(uint32_t Offset) {
203 write_uint32_le(Data.Name + 0, 0);
204 write_uint32_le(Data.Name + 4, Offset);
207 /// logic to decide if the symbol should be reported in the symbol table
208 bool COFFSymbol::should_keep() const {
209 // no section means its external, keep it
213 // if it has relocations pointing at it, keep it
214 if (Relocations > 0) {
215 assert(Section->Number != -1 && "Sections with relocations must be real!");
219 // if the section its in is being droped, drop it
220 if (Section->Number == -1)
223 // if it is the section symbol, keep it
224 if (Section->Symbol == this)
227 // if its temporary, drop it
228 if (MCData && MCData->getSymbol().isTemporary())
231 // otherwise, keep it
235 //------------------------------------------------------------------------------
236 // Section class implementation
238 COFFSection::COFFSection(StringRef name)
242 memset(&Header, 0, sizeof(Header));
245 size_t COFFSection::size() {
246 return COFF::SectionSize;
249 //------------------------------------------------------------------------------
250 // WinCOFFObjectWriter class implementation
252 WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
254 : MCObjectWriter(OS, true), TargetObjectWriter(MOTW) {
255 memset(&Header, 0, sizeof(Header));
257 Header.Machine = TargetObjectWriter->getMachine();
260 COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
261 return createCOFFEntity<COFFSymbol>(Name, Symbols);
264 COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
265 symbol_map::iterator i = SymbolMap.find(Symbol);
266 if (i != SymbolMap.end())
268 COFFSymbol *RetSymbol
269 = createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
270 SymbolMap[Symbol] = RetSymbol;
274 COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) {
275 return createCOFFEntity<COFFSection>(Name, Sections);
278 /// A template used to lookup or create a symbol/section, and initialize it if
280 template <typename object_t, typename list_t>
281 object_t *WinCOFFObjectWriter::createCOFFEntity(StringRef Name,
283 List.push_back(make_unique<object_t>(Name));
285 return List.back().get();
288 /// This function takes a section data object from the assembler
289 /// and creates the associated COFF section staging object.
290 void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
291 assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
292 && "Got non-COFF section in the COFF backend!");
293 // FIXME: Not sure how to verify this (at least in a debug build).
294 MCSectionCOFF const &Sec =
295 static_cast<MCSectionCOFF const &>(SectionData.getSection());
297 COFFSection *coff_section = createSection(Sec.getSectionName());
298 COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
299 if (Sec.getSelection() != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
300 if (const MCSymbol *S = Sec.getCOMDATSymbol()) {
301 COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(S);
302 if (COMDATSymbol->Section)
303 report_fatal_error("two sections have the same comdat");
304 COMDATSymbol->Section = coff_section;
308 coff_section->Symbol = coff_symbol;
309 coff_symbol->Section = coff_section;
310 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
312 // In this case the auxiliary symbol is a Section Definition.
313 coff_symbol->Aux.resize(1);
314 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
315 coff_symbol->Aux[0].AuxType = ATSectionDefinition;
316 coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
318 coff_section->Header.Characteristics = Sec.getCharacteristics();
320 uint32_t &Characteristics = coff_section->Header.Characteristics;
321 switch (SectionData.getAlignment()) {
322 case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break;
323 case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break;
324 case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break;
325 case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break;
326 case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break;
327 case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break;
328 case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break;
329 case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break;
330 case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break;
331 case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break;
332 case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
333 case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
334 case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
335 case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
337 llvm_unreachable("unsupported section alignment");
340 // Bind internal COFF section to MC section.
341 coff_section->MCData = &SectionData;
342 SectionMap[&SectionData.getSection()] = coff_section;
345 static uint64_t getSymbolValue(const MCSymbolData &Data,
346 const MCAsmLayout &Layout) {
347 if (Data.isCommon() && Data.isExternal())
348 return Data.getCommonSize();
351 if (!Layout.getSymbolOffset(&Data, Res))
357 /// This function takes a symbol data object from the assembler
358 /// and creates the associated COFF symbol staging object.
359 void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
360 MCAssembler &Assembler,
361 const MCAsmLayout &Layout) {
362 MCSymbol const &Symbol = SymbolData.getSymbol();
363 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol);
364 SymbolMap[&Symbol] = coff_symbol;
366 if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
367 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
369 if (Symbol.isVariable()) {
370 const MCSymbolRefExpr *SymRef =
371 dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue());
374 report_fatal_error("Weak externals may only alias symbols");
376 coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol());
378 std::string WeakName = std::string(".weak.")
379 + Symbol.getName().str()
381 COFFSymbol *WeakDefault = createSymbol(WeakName);
382 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
383 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
384 WeakDefault->Data.Type = 0;
385 WeakDefault->Data.Value = 0;
386 coff_symbol->Other = WeakDefault;
389 // Setup the Weak External auxiliary symbol.
390 coff_symbol->Aux.resize(1);
391 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
392 coff_symbol->Aux[0].AuxType = ATWeakExternal;
393 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
394 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
395 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
397 coff_symbol->MCData = &SymbolData;
399 const MCSymbolData &ResSymData = Assembler.getSymbolData(Symbol);
400 const MCSymbol *Base = Layout.getBaseSymbol(Symbol);
401 coff_symbol->Data.Value = getSymbolValue(ResSymData, Layout);
403 coff_symbol->Data.Type = (ResSymData.getFlags() & 0x0000FFFF) >> 0;
404 coff_symbol->Data.StorageClass = (ResSymData.getFlags() & 0x00FF0000) >> 16;
406 // If no storage class was specified in the streamer, define it here.
407 if (coff_symbol->Data.StorageClass == 0) {
409 ResSymData.isExternal() ||
410 (!ResSymData.getFragment() && !ResSymData.getSymbol().isVariable());
412 coff_symbol->Data.StorageClass = IsExternal
413 ? COFF::IMAGE_SYM_CLASS_EXTERNAL
414 : COFF::IMAGE_SYM_CLASS_STATIC;
418 coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
420 const MCSymbolData &BaseData = Assembler.getSymbolData(*Base);
421 if (BaseData.getFragment()) {
423 SectionMap[&BaseData.getFragment()->getParent()->getSection()];
425 if (coff_symbol->Section && coff_symbol->Section != Sec)
426 report_fatal_error("conflicting sections for symbol");
428 coff_symbol->Section = Sec;
432 coff_symbol->MCData = &ResSymData;
436 // Maximum offsets for different string table entry encodings.
437 static const unsigned Max6DecimalOffset = 999999;
438 static const unsigned Max7DecimalOffset = 9999999;
439 static const uint64_t MaxBase64Offset = 0xFFFFFFFFFULL; // 64^6, including 0
441 // Encode a string table entry offset in base 64, padded to 6 chars, and
442 // prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
443 // Buffer must be at least 8 bytes large. No terminating null appended.
444 static void encodeBase64StringEntry(char* Buffer, uint64_t Value) {
445 assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
446 "Illegal section name encoding for value");
448 static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
449 "abcdefghijklmnopqrstuvwxyz"
455 char* Ptr = Buffer + 7;
456 for (unsigned i = 0; i < 6; ++i) {
457 unsigned Rem = Value % 64;
459 *(Ptr--) = Alphabet[Rem];
463 void WinCOFFObjectWriter::SetSectionName(COFFSection &S) {
464 if (S.Name.size() > COFF::NameSize) {
465 uint64_t StringTableEntry = Strings.getOffset(S.Name);
467 if (StringTableEntry <= Max6DecimalOffset) {
468 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
469 } else if (StringTableEntry <= Max7DecimalOffset) {
470 // With seven digits, we have to skip the terminating null. Because
471 // sprintf always appends it, we use a larger temporary buffer.
472 char buffer[9] = { };
473 std::sprintf(buffer, "/%d", unsigned(StringTableEntry));
474 std::memcpy(S.Header.Name, buffer, 8);
475 } else if (StringTableEntry <= MaxBase64Offset) {
476 // Starting with 10,000,000, offsets are encoded as base64.
477 encodeBase64StringEntry(S.Header.Name, StringTableEntry);
479 report_fatal_error("COFF string table is greater than 64 GB.");
482 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
485 void WinCOFFObjectWriter::SetSymbolName(COFFSymbol &S) {
486 if (S.Name.size() > COFF::NameSize)
487 S.set_name_offset(Strings.getOffset(S.Name));
489 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
492 bool WinCOFFObjectWriter::ExportSymbol(const MCSymbol &Symbol,
494 // This doesn't seem to be right. Strings referred to from the .data section
495 // need symbols so they can be linked to code in the .text section right?
497 // return Asm.isSymbolLinkerVisible(Symbol);
499 // Non-temporary labels should always be visible to the linker.
500 if (!Symbol.isTemporary())
503 // Absolute temporary labels are never visible.
504 if (!Symbol.isInSection())
507 // For now, all non-variable symbols are exported,
508 // the linker will sort the rest out for us.
509 return !Symbol.isVariable();
512 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
513 return (S->Header.Characteristics
514 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
517 //------------------------------------------------------------------------------
518 // entity writing methods
520 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
522 WriteLE16(COFF::IMAGE_FILE_MACHINE_UNKNOWN);
524 WriteLE16(COFF::BigObjHeader::MinBigObjectVersion);
525 WriteLE16(Header.Machine);
526 WriteLE32(Header.TimeDateStamp);
527 for (uint8_t MagicChar : COFF::BigObjMagic)
533 WriteLE32(Header.NumberOfSections);
534 WriteLE32(Header.PointerToSymbolTable);
535 WriteLE32(Header.NumberOfSymbols);
537 WriteLE16(Header.Machine);
538 WriteLE16(static_cast<int16_t>(Header.NumberOfSections));
539 WriteLE32(Header.TimeDateStamp);
540 WriteLE32(Header.PointerToSymbolTable);
541 WriteLE32(Header.NumberOfSymbols);
542 WriteLE16(Header.SizeOfOptionalHeader);
543 WriteLE16(Header.Characteristics);
547 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol &S) {
548 WriteBytes(StringRef(S.Data.Name, COFF::NameSize));
549 WriteLE32(S.Data.Value);
551 WriteLE32(S.Data.SectionNumber);
553 WriteLE16(static_cast<int16_t>(S.Data.SectionNumber));
554 WriteLE16(S.Data.Type);
555 Write8(S.Data.StorageClass);
556 Write8(S.Data.NumberOfAuxSymbols);
557 WriteAuxiliarySymbols(S.Aux);
560 void WinCOFFObjectWriter::WriteAuxiliarySymbols(
561 const COFFSymbol::AuxiliarySymbols &S) {
562 for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
565 case ATFunctionDefinition:
566 WriteLE32(i->Aux.FunctionDefinition.TagIndex);
567 WriteLE32(i->Aux.FunctionDefinition.TotalSize);
568 WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
569 WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
570 WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
572 WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
574 case ATbfAndefSymbol:
575 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
576 WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
577 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
578 WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
579 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
581 WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
584 WriteLE32(i->Aux.WeakExternal.TagIndex);
585 WriteLE32(i->Aux.WeakExternal.Characteristics);
586 WriteZeros(sizeof(i->Aux.WeakExternal.unused));
588 WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
592 StringRef(reinterpret_cast<const char *>(&i->Aux),
593 UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size));
595 case ATSectionDefinition:
596 WriteLE32(i->Aux.SectionDefinition.Length);
597 WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
598 WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
599 WriteLE32(i->Aux.SectionDefinition.CheckSum);
600 WriteLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number));
601 Write8(i->Aux.SectionDefinition.Selection);
602 WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
603 WriteLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number >> 16));
605 WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
611 void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
612 WriteBytes(StringRef(S.Name, COFF::NameSize));
614 WriteLE32(S.VirtualSize);
615 WriteLE32(S.VirtualAddress);
616 WriteLE32(S.SizeOfRawData);
617 WriteLE32(S.PointerToRawData);
618 WriteLE32(S.PointerToRelocations);
619 WriteLE32(S.PointerToLineNumbers);
620 WriteLE16(S.NumberOfRelocations);
621 WriteLE16(S.NumberOfLineNumbers);
622 WriteLE32(S.Characteristics);
625 void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
626 WriteLE32(R.VirtualAddress);
627 WriteLE32(R.SymbolTableIndex);
631 ////////////////////////////////////////////////////////////////////////////////
632 // MCObjectWriter interface implementations
634 void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
635 const MCAsmLayout &Layout) {
636 // "Define" each section & symbol. This creates section & symbol
637 // entries in the staging area.
638 for (const auto & Section : Asm)
639 DefineSection(Section);
641 for (MCSymbolData &SD : Asm.symbols())
642 if (ExportSymbol(SD.getSymbol(), Asm))
643 DefineSymbol(SD, Asm, Layout);
646 void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
647 const MCAsmLayout &Layout,
648 const MCFragment *Fragment,
649 const MCFixup &Fixup,
652 uint64_t &FixedValue) {
653 assert(Target.getSymA() && "Relocation must reference a symbol!");
655 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
656 const MCSymbol &A = Symbol.AliasedSymbol();
657 if (!Asm.hasSymbolData(A))
658 Asm.getContext().FatalError(
660 Twine("symbol '") + A.getName() + "' can not be undefined");
662 const MCSymbolData &A_SD = Asm.getSymbolData(A);
664 MCSectionData const *SectionData = Fragment->getParent();
666 // Mark this symbol as requiring an entry in the symbol table.
667 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
668 "Section must already have been defined in ExecutePostLayoutBinding!");
669 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
670 "Symbol must already have been defined in ExecutePostLayoutBinding!");
672 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
673 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
674 const MCSymbolRefExpr *SymB = Target.getSymB();
675 bool CrossSection = false;
678 const MCSymbol *B = &SymB->getSymbol();
679 const MCSymbolData &B_SD = Asm.getSymbolData(*B);
680 if (!B_SD.getFragment())
681 Asm.getContext().FatalError(
683 Twine("symbol '") + B->getName() +
684 "' can not be undefined in a subtraction expression");
686 if (!A_SD.getFragment())
687 Asm.getContext().FatalError(
689 Twine("symbol '") + Symbol.getName() +
690 "' can not be undefined in a subtraction expression");
692 CrossSection = &Symbol.getSection() != &B->getSection();
694 // Offset of the symbol in the section
695 int64_t a = Layout.getSymbolOffset(&B_SD);
697 // Ofeset of the relocation in the section
698 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
701 // In the case where we have SymbA and SymB, we just need to store the delta
702 // between the two symbols. Update FixedValue to account for the delta, and
703 // skip recording the relocation.
707 FixedValue = Target.getConstant();
710 COFFRelocation Reloc;
712 Reloc.Data.SymbolTableIndex = 0;
713 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
715 // Turn relocations for temporary symbols into section relocations.
716 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
717 Reloc.Symb = coff_symbol->Section->Symbol;
718 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->getFragment()) +
719 coff_symbol->MCData->getOffset();
721 Reloc.Symb = coff_symbol;
723 ++Reloc.Symb->Relocations;
725 Reloc.Data.VirtualAddress += Fixup.getOffset();
726 Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup,
729 // FIXME: Can anyone explain what this does other than adjust for the size
731 if ((Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64 &&
732 Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32) ||
733 (Header.Machine == COFF::IMAGE_FILE_MACHINE_I386 &&
734 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32))
737 if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) {
738 switch (Reloc.Data.Type) {
739 case COFF::IMAGE_REL_ARM_ABSOLUTE:
740 case COFF::IMAGE_REL_ARM_ADDR32:
741 case COFF::IMAGE_REL_ARM_ADDR32NB:
742 case COFF::IMAGE_REL_ARM_TOKEN:
743 case COFF::IMAGE_REL_ARM_SECTION:
744 case COFF::IMAGE_REL_ARM_SECREL:
746 case COFF::IMAGE_REL_ARM_BRANCH11:
747 case COFF::IMAGE_REL_ARM_BLX11:
748 // IMAGE_REL_ARM_BRANCH11 and IMAGE_REL_ARM_BLX11 are only used for
749 // pre-ARMv7, which implicitly rules it out of ARMNT (it would be valid
751 case COFF::IMAGE_REL_ARM_BRANCH24:
752 case COFF::IMAGE_REL_ARM_BLX24:
753 case COFF::IMAGE_REL_ARM_MOV32A:
754 // IMAGE_REL_ARM_BRANCH24, IMAGE_REL_ARM_BLX24, IMAGE_REL_ARM_MOV32A are
755 // only used for ARM mode code, which is documented as being unsupported
756 // by Windows on ARM. Empirical proof indicates that masm is able to
757 // generate the relocations however the rest of the MSVC toolchain is
758 // unable to handle it.
759 llvm_unreachable("unsupported relocation");
761 case COFF::IMAGE_REL_ARM_MOV32T:
763 case COFF::IMAGE_REL_ARM_BRANCH20T:
764 case COFF::IMAGE_REL_ARM_BRANCH24T:
765 case COFF::IMAGE_REL_ARM_BLX23T:
766 // IMAGE_REL_BRANCH20T, IMAGE_REL_ARM_BRANCH24T, IMAGE_REL_ARM_BLX23T all
767 // perform a 4 byte adjustment to the relocation. Relative branches are
768 // offset by 4 on ARM, however, because there is no RELA relocations, all
769 // branches are offset by 4.
770 FixedValue = FixedValue + 4;
775 if (TargetObjectWriter->recordRelocation(Fixup))
776 coff_section->Relocations.push_back(Reloc);
779 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
780 const MCAsmLayout &Layout) {
781 size_t SectionsSize = Sections.size();
782 if (SectionsSize > static_cast<size_t>(INT32_MAX))
784 "PE COFF object files can't have more than 2147483647 sections");
786 // Assign symbol and section indexes and offsets.
787 int32_t NumberOfSections = static_cast<int32_t>(SectionsSize);
789 UseBigObj = NumberOfSections > COFF::MaxNumberOfSections16;
791 DenseMap<COFFSection *, int32_t> SectionIndices(
792 NextPowerOf2(NumberOfSections));
794 // Assign section numbers.
796 for (const auto &Section : Sections) {
797 SectionIndices[Section.get()] = Number;
798 Section->Number = Number;
799 Section->Symbol->Data.SectionNumber = Number;
800 Section->Symbol->Aux[0].Aux.SectionDefinition.Number = Number;
804 Header.NumberOfSections = NumberOfSections;
805 Header.NumberOfSymbols = 0;
807 for (auto FI = Asm.file_names_begin(), FE = Asm.file_names_end();
809 // round up to calculate the number of auxiliary symbols required
810 unsigned SymbolSize = UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size;
811 unsigned Count = (FI->size() + SymbolSize - 1) / SymbolSize;
813 COFFSymbol *file = createSymbol(".file");
814 file->Data.SectionNumber = COFF::IMAGE_SYM_DEBUG;
815 file->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE;
816 file->Aux.resize(Count);
819 unsigned Length = FI->size();
820 for (auto & Aux : file->Aux) {
821 Aux.AuxType = ATFile;
823 if (Length > SymbolSize) {
824 memcpy(&Aux.Aux, FI->c_str() + Offset, SymbolSize);
825 Length = Length - SymbolSize;
827 memcpy(&Aux.Aux, FI->c_str() + Offset, Length);
828 memset((char *)&Aux.Aux + Length, 0, SymbolSize - Length);
832 Offset += SymbolSize;
836 for (auto &Symbol : Symbols) {
837 // Update section number & offset for symbols that have them.
839 Symbol->Data.SectionNumber = Symbol->Section->Number;
840 if (Symbol->should_keep()) {
841 Symbol->Index = Header.NumberOfSymbols++;
842 // Update auxiliary symbol info.
843 Symbol->Data.NumberOfAuxSymbols = Symbol->Aux.size();
844 Header.NumberOfSymbols += Symbol->Data.NumberOfAuxSymbols;
849 // Build string table.
850 for (const auto &S : Sections)
851 if (S->Name.size() > COFF::NameSize)
852 Strings.add(S->Name);
853 for (const auto &S : Symbols)
854 if (S->should_keep() && S->Name.size() > COFF::NameSize)
855 Strings.add(S->Name);
856 Strings.finalize(StringTableBuilder::WinCOFF);
859 for (const auto &S : Sections)
861 for (auto &S : Symbols)
862 if (S->should_keep())
865 // Fixup weak external references.
866 for (auto & Symbol : Symbols) {
868 assert(Symbol->Index != -1);
869 assert(Symbol->Aux.size() == 1 && "Symbol must contain one aux symbol!");
870 assert(Symbol->Aux[0].AuxType == ATWeakExternal &&
871 "Symbol's aux symbol must be a Weak External!");
872 Symbol->Aux[0].Aux.WeakExternal.TagIndex = Symbol->Other->Index;
876 // Fixup associative COMDAT sections.
877 for (auto & Section : Sections) {
878 if (Section->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
879 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
882 const MCSectionCOFF &MCSec =
883 static_cast<const MCSectionCOFF &>(Section->MCData->getSection());
885 const MCSymbol *COMDAT = MCSec.getCOMDATSymbol();
887 COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(COMDAT);
888 assert(COMDATSymbol);
889 COFFSection *Assoc = COMDATSymbol->Section;
892 Twine("Missing associated COMDAT section for section ") +
893 MCSec.getSectionName());
895 // Skip this section if the associated section is unused.
896 if (Assoc->Number == -1)
899 Section->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
903 // Assign file offsets to COFF object file structures.
908 offset += COFF::Header32Size;
910 offset += COFF::Header16Size;
911 offset += COFF::SectionSize * Header.NumberOfSections;
913 for (const auto & Section : Asm) {
914 COFFSection *Sec = SectionMap[&Section.getSection()];
916 if (Sec->Number == -1)
919 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(&Section);
921 if (IsPhysicalSection(Sec)) {
922 Sec->Header.PointerToRawData = offset;
924 offset += Sec->Header.SizeOfRawData;
927 if (Sec->Relocations.size() > 0) {
928 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
930 if (RelocationsOverflow) {
931 // Signal overflow by setting NumberOfRelocations to max value. Actual
932 // size is found in reloc #0. Microsoft tools understand this.
933 Sec->Header.NumberOfRelocations = 0xffff;
935 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
937 Sec->Header.PointerToRelocations = offset;
939 if (RelocationsOverflow) {
940 // Reloc #0 will contain actual count, so make room for it.
941 offset += COFF::RelocationSize;
944 offset += COFF::RelocationSize * Sec->Relocations.size();
946 for (auto & Relocation : Sec->Relocations) {
947 assert(Relocation.Symb->Index != -1);
948 Relocation.Data.SymbolTableIndex = Relocation.Symb->Index;
952 assert(Sec->Symbol->Aux.size() == 1 &&
953 "Section's symbol must have one aux!");
954 AuxSymbol &Aux = Sec->Symbol->Aux[0];
955 assert(Aux.AuxType == ATSectionDefinition &&
956 "Section's symbol's aux symbol must be a Section Definition!");
957 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
958 Aux.Aux.SectionDefinition.NumberOfRelocations =
959 Sec->Header.NumberOfRelocations;
960 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
961 Sec->Header.NumberOfLineNumbers;
964 Header.PointerToSymbolTable = offset;
966 // We want a deterministic output. It looks like GNU as also writes 0 in here.
967 Header.TimeDateStamp = 0;
969 // Write it all to disk...
970 WriteFileHeader(Header);
973 sections::iterator i, ie;
974 MCAssembler::const_iterator j, je;
976 for (auto & Section : Sections) {
977 if (Section->Number != -1) {
978 if (Section->Relocations.size() >= 0xffff)
979 Section->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
980 WriteSectionHeader(Section->Header);
984 for (i = Sections.begin(), ie = Sections.end(),
985 j = Asm.begin(), je = Asm.end();
986 (i != ie) && (j != je); ++i, ++j) {
988 if ((*i)->Number == -1)
991 if ((*i)->Header.PointerToRawData != 0) {
992 assert(OS.tell() == (*i)->Header.PointerToRawData &&
993 "Section::PointerToRawData is insane!");
995 Asm.writeSectionData(j, Layout);
998 if ((*i)->Relocations.size() > 0) {
999 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
1000 "Section::PointerToRelocations is insane!");
1002 if ((*i)->Relocations.size() >= 0xffff) {
1003 // In case of overflow, write actual relocation count as first
1004 // relocation. Including the synthetic reloc itself (+ 1).
1006 r.VirtualAddress = (*i)->Relocations.size() + 1;
1007 r.SymbolTableIndex = 0;
1012 for (const auto & Relocation : (*i)->Relocations)
1013 WriteRelocation(Relocation.Data);
1015 assert((*i)->Header.PointerToRelocations == 0 &&
1016 "Section::PointerToRelocations is insane!");
1020 assert(OS.tell() == Header.PointerToSymbolTable &&
1021 "Header::PointerToSymbolTable is insane!");
1023 for (auto & Symbol : Symbols)
1024 if (Symbol->Index != -1)
1025 WriteSymbol(*Symbol);
1027 OS.write(Strings.data().data(), Strings.data().size());
1030 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :
1034 // Pin the vtable to this file.
1035 void MCWinCOFFObjectTargetWriter::anchor() {}
1037 //------------------------------------------------------------------------------
1038 // WinCOFFObjectWriter factory function
1041 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
1043 return new WinCOFFObjectWriter(MOTW, OS);