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/STLExtras.h"
17 #include "llvm/ADT/StringMap.h"
18 #include "llvm/ADT/StringRef.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;
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_pwrite_stream &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(const MCSymbol &Symbol, 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 bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
174 const MCSymbol &SymA,
175 const MCFragment &FB, bool InSet,
176 bool IsPCRel) const override;
178 bool isWeak(const MCSymbol &Sym) const override;
180 void RecordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
181 const MCFragment *Fragment, const MCFixup &Fixup,
182 MCValue Target, bool &IsPCRel,
183 uint64_t &FixedValue) override;
185 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
189 static inline void write_uint32_le(void *Data, uint32_t Value) {
190 support::endian::write<uint32_t, support::little, support::unaligned>(Data,
194 //------------------------------------------------------------------------------
195 // Symbol class implementation
197 COFFSymbol::COFFSymbol(StringRef name)
198 : Name(name.begin(), name.end()), Other(nullptr), Section(nullptr),
199 Relocations(0), MC(nullptr) {
200 memset(&Data, 0, sizeof(Data));
203 // In the case that the name does not fit within 8 bytes, the offset
204 // into the string table is stored in the last 4 bytes instead, leaving
205 // the first 4 bytes as 0.
206 void COFFSymbol::set_name_offset(uint32_t Offset) {
207 write_uint32_le(Data.Name + 0, 0);
208 write_uint32_le(Data.Name + 4, Offset);
211 /// logic to decide if the symbol should be reported in the symbol table
212 bool COFFSymbol::should_keep() const {
213 // no section means its external, keep it
217 // if it has relocations pointing at it, keep it
218 if (Relocations > 0) {
219 assert(Section->Number != -1 && "Sections with relocations must be real!");
223 // if the section its in is being droped, drop it
224 if (Section->Number == -1)
227 // if it is the section symbol, keep it
228 if (Section->Symbol == this)
231 // if its temporary, drop it
232 if (MC && MC->isTemporary())
235 // otherwise, keep it
239 //------------------------------------------------------------------------------
240 // Section class implementation
242 COFFSection::COFFSection(StringRef name)
246 memset(&Header, 0, sizeof(Header));
249 size_t COFFSection::size() {
250 return COFF::SectionSize;
253 //------------------------------------------------------------------------------
254 // WinCOFFObjectWriter class implementation
256 WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
257 raw_pwrite_stream &OS)
258 : MCObjectWriter(OS, true), TargetObjectWriter(MOTW) {
259 memset(&Header, 0, sizeof(Header));
261 Header.Machine = TargetObjectWriter->getMachine();
264 COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
265 return createCOFFEntity<COFFSymbol>(Name, Symbols);
268 COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol *Symbol) {
269 symbol_map::iterator i = SymbolMap.find(Symbol);
270 if (i != SymbolMap.end())
272 COFFSymbol *RetSymbol =
273 createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
274 SymbolMap[Symbol] = RetSymbol;
278 COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) {
279 return createCOFFEntity<COFFSection>(Name, Sections);
282 /// A template used to lookup or create a symbol/section, and initialize it if
284 template <typename object_t, typename list_t>
285 object_t *WinCOFFObjectWriter::createCOFFEntity(StringRef Name,
287 List.push_back(make_unique<object_t>(Name));
289 return List.back().get();
292 /// This function takes a section data object from the assembler
293 /// and creates the associated COFF section staging object.
294 void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
295 assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
296 && "Got non-COFF section in the COFF backend!");
297 // FIXME: Not sure how to verify this (at least in a debug build).
298 MCSectionCOFF const &Sec =
299 static_cast<MCSectionCOFF const &>(SectionData.getSection());
301 COFFSection *coff_section = createSection(Sec.getSectionName());
302 COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
303 if (Sec.getSelection() != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
304 if (const MCSymbol *S = Sec.getCOMDATSymbol()) {
305 COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(S);
306 if (COMDATSymbol->Section)
307 report_fatal_error("two sections have the same comdat");
308 COMDATSymbol->Section = coff_section;
312 coff_section->Symbol = coff_symbol;
313 coff_symbol->Section = coff_section;
314 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
316 // In this case the auxiliary symbol is a Section Definition.
317 coff_symbol->Aux.resize(1);
318 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
319 coff_symbol->Aux[0].AuxType = ATSectionDefinition;
320 coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
322 coff_section->Header.Characteristics = Sec.getCharacteristics();
324 uint32_t &Characteristics = coff_section->Header.Characteristics;
325 switch (Sec.getAlignment()) {
326 case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break;
327 case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break;
328 case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break;
329 case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break;
330 case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break;
331 case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break;
332 case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break;
333 case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break;
334 case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break;
335 case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break;
336 case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
337 case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
338 case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
339 case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
341 llvm_unreachable("unsupported section alignment");
344 // Bind internal COFF section to MC section.
345 coff_section->MCData = &SectionData;
346 SectionMap[&SectionData.getSection()] = coff_section;
349 static uint64_t getSymbolValue(const MCSymbol &Symbol,
350 const MCAsmLayout &Layout) {
351 const MCSymbolData &Data = Symbol.getData();
352 if (Data.isCommon() && Data.isExternal())
353 return Data.getCommonSize();
356 if (!Layout.getSymbolOffset(Symbol, Res))
362 /// This function takes a symbol data object from the assembler
363 /// and creates the associated COFF symbol staging object.
364 void WinCOFFObjectWriter::DefineSymbol(const MCSymbol &Symbol,
365 MCAssembler &Assembler,
366 const MCAsmLayout &Layout) {
367 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol);
368 SymbolMap[&Symbol] = coff_symbol;
370 if (Symbol.getData().getFlags() & COFF::SF_WeakExternal) {
371 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
373 if (Symbol.isVariable()) {
374 const MCSymbolRefExpr *SymRef =
375 dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue());
378 report_fatal_error("Weak externals may only alias symbols");
380 coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol());
382 std::string WeakName = (".weak." + Symbol.getName() + ".default").str();
383 COFFSymbol *WeakDefault = createSymbol(WeakName);
384 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
385 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
386 WeakDefault->Data.Type = 0;
387 WeakDefault->Data.Value = 0;
388 coff_symbol->Other = WeakDefault;
391 // Setup the Weak External auxiliary symbol.
392 coff_symbol->Aux.resize(1);
393 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
394 coff_symbol->Aux[0].AuxType = ATWeakExternal;
395 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
396 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
397 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
399 coff_symbol->MC = &Symbol;
401 const MCSymbolData &ResSymData = Assembler.getSymbolData(Symbol);
402 const MCSymbol *Base = Layout.getBaseSymbol(Symbol);
403 coff_symbol->Data.Value = getSymbolValue(Symbol, Layout);
405 coff_symbol->Data.Type = (ResSymData.getFlags() & 0x0000FFFF) >> 0;
406 coff_symbol->Data.StorageClass = (ResSymData.getFlags() & 0x00FF0000) >> 16;
408 // If no storage class was specified in the streamer, define it here.
409 if (coff_symbol->Data.StorageClass == 0) {
410 bool IsExternal = ResSymData.isExternal() ||
411 (!ResSymData.getFragment() && !Symbol.isVariable());
413 coff_symbol->Data.StorageClass = IsExternal
414 ? COFF::IMAGE_SYM_CLASS_EXTERNAL
415 : COFF::IMAGE_SYM_CLASS_STATIC;
419 coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
421 const MCSymbolData &BaseData = Assembler.getSymbolData(*Base);
422 if (BaseData.getFragment()) {
424 SectionMap[&BaseData.getFragment()->getParent()->getSection()];
426 if (coff_symbol->Section && coff_symbol->Section != Sec)
427 report_fatal_error("conflicting sections for symbol");
429 coff_symbol->Section = Sec;
433 coff_symbol->MC = &Symbol;
437 // Maximum offsets for different string table entry encodings.
438 static const unsigned Max6DecimalOffset = 999999;
439 static const unsigned Max7DecimalOffset = 9999999;
440 static const uint64_t MaxBase64Offset = 0xFFFFFFFFFULL; // 64^6, including 0
442 // Encode a string table entry offset in base 64, padded to 6 chars, and
443 // prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
444 // Buffer must be at least 8 bytes large. No terminating null appended.
445 static void encodeBase64StringEntry(char* Buffer, uint64_t Value) {
446 assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
447 "Illegal section name encoding for value");
449 static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
450 "abcdefghijklmnopqrstuvwxyz"
456 char* Ptr = Buffer + 7;
457 for (unsigned i = 0; i < 6; ++i) {
458 unsigned Rem = Value % 64;
460 *(Ptr--) = Alphabet[Rem];
464 void WinCOFFObjectWriter::SetSectionName(COFFSection &S) {
465 if (S.Name.size() > COFF::NameSize) {
466 uint64_t StringTableEntry = Strings.getOffset(S.Name);
468 if (StringTableEntry <= Max6DecimalOffset) {
469 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
470 } else if (StringTableEntry <= Max7DecimalOffset) {
471 // With seven digits, we have to skip the terminating null. Because
472 // sprintf always appends it, we use a larger temporary buffer.
473 char buffer[9] = { };
474 std::sprintf(buffer, "/%d", unsigned(StringTableEntry));
475 std::memcpy(S.Header.Name, buffer, 8);
476 } else if (StringTableEntry <= MaxBase64Offset) {
477 // Starting with 10,000,000, offsets are encoded as base64.
478 encodeBase64StringEntry(S.Header.Name, StringTableEntry);
480 report_fatal_error("COFF string table is greater than 64 GB.");
483 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
486 void WinCOFFObjectWriter::SetSymbolName(COFFSymbol &S) {
487 if (S.Name.size() > COFF::NameSize)
488 S.set_name_offset(Strings.getOffset(S.Name));
490 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
493 bool WinCOFFObjectWriter::ExportSymbol(const MCSymbol &Symbol,
495 // This doesn't seem to be right. Strings referred to from the .data section
496 // need symbols so they can be linked to code in the .text section right?
498 // return Asm.isSymbolLinkerVisible(Symbol);
500 // Non-temporary labels should always be visible to the linker.
501 if (!Symbol.isTemporary())
504 // Absolute temporary labels are never visible.
505 if (!Symbol.isInSection())
508 // For now, all non-variable symbols are exported,
509 // the linker will sort the rest out for us.
510 return !Symbol.isVariable();
513 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
514 return (S->Header.Characteristics
515 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
518 //------------------------------------------------------------------------------
519 // entity writing methods
521 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
523 WriteLE16(COFF::IMAGE_FILE_MACHINE_UNKNOWN);
525 WriteLE16(COFF::BigObjHeader::MinBigObjectVersion);
526 WriteLE16(Header.Machine);
527 WriteLE32(Header.TimeDateStamp);
528 WriteBytes(StringRef(COFF::BigObjMagic, sizeof(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.getSectionData());
641 for (const MCSymbol &Symbol : Asm.symbols())
642 if (ExportSymbol(Symbol, Asm))
643 DefineSymbol(Symbol, Asm, Layout);
646 bool WinCOFFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
647 const MCAssembler &Asm, const MCSymbol &SymA, const MCFragment &FB,
648 bool InSet, bool IsPCRel) const {
649 // MS LINK expects to be able to replace all references to a function with a
650 // thunk to implement their /INCREMENTAL feature. Make sure we don't optimize
651 // away any relocations to functions.
652 if ((((SymA.getData().getFlags() & COFF::SF_TypeMask) >>
653 COFF::SF_TypeShift) >>
654 COFF::SCT_COMPLEX_TYPE_SHIFT) == COFF::IMAGE_SYM_DTYPE_FUNCTION)
656 return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(Asm, SymA, FB,
660 bool WinCOFFObjectWriter::isWeak(const MCSymbol &Sym) const {
661 const MCSymbolData &SD = Sym.getData();
662 if (!SD.isExternal())
665 if (!Sym.isInSection())
668 const auto &Sec = cast<MCSectionCOFF>(Sym.getSection());
669 if (!Sec.getCOMDATSymbol())
672 // It looks like for COFF it is invalid to replace a reference to a global
673 // in a comdat with a reference to a local.
674 // FIXME: Add a specification reference if available.
678 void WinCOFFObjectWriter::RecordRelocation(
679 MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment,
680 const MCFixup &Fixup, MCValue Target, bool &IsPCRel, uint64_t &FixedValue) {
681 assert(Target.getSymA() && "Relocation must reference a symbol!");
683 const MCSymbol &Symbol = Target.getSymA()->getSymbol();
684 const MCSymbol &A = Symbol;
685 if (!Asm.hasSymbolData(A))
686 Asm.getContext().reportFatalError(
688 Twine("symbol '") + A.getName() + "' can not be undefined");
690 const MCSymbolData &A_SD = Asm.getSymbolData(A);
692 MCSectionData const *SectionData = Fragment->getParent();
694 // Mark this symbol as requiring an entry in the symbol table.
695 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
696 "Section must already have been defined in ExecutePostLayoutBinding!");
697 assert(SymbolMap.find(&A) != SymbolMap.end() &&
698 "Symbol must already have been defined in ExecutePostLayoutBinding!");
700 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
701 COFFSymbol *coff_symbol = SymbolMap[&A];
702 const MCSymbolRefExpr *SymB = Target.getSymB();
703 bool CrossSection = false;
706 const MCSymbol *B = &SymB->getSymbol();
707 const MCSymbolData &B_SD = Asm.getSymbolData(*B);
708 if (!B_SD.getFragment())
709 Asm.getContext().reportFatalError(
711 Twine("symbol '") + B->getName() +
712 "' can not be undefined in a subtraction expression");
714 if (!A_SD.getFragment())
715 Asm.getContext().reportFatalError(
717 Twine("symbol '") + Symbol.getName() +
718 "' can not be undefined in a subtraction expression");
720 CrossSection = &Symbol.getSection() != &B->getSection();
722 // Offset of the symbol in the section
723 int64_t OffsetOfB = Layout.getSymbolOffset(*B);
725 // In the case where we have SymbA and SymB, we just need to store the delta
726 // between the two symbols. Update FixedValue to account for the delta, and
727 // skip recording the relocation.
729 int64_t OffsetOfA = Layout.getSymbolOffset(A);
730 FixedValue = (OffsetOfA - OffsetOfB) + Target.getConstant();
734 // Offset of the relocation in the section
735 int64_t OffsetOfRelocation =
736 Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
738 FixedValue = (OffsetOfRelocation - OffsetOfB) + Target.getConstant();
740 FixedValue = Target.getConstant();
743 COFFRelocation Reloc;
745 Reloc.Data.SymbolTableIndex = 0;
746 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
748 // Turn relocations for temporary symbols into section relocations.
749 if (coff_symbol->MC->isTemporary() || CrossSection) {
750 Reloc.Symb = coff_symbol->Section->Symbol;
752 Layout.getFragmentOffset(coff_symbol->MC->getData().getFragment()) +
753 coff_symbol->MC->getData().getOffset();
755 Reloc.Symb = coff_symbol;
757 ++Reloc.Symb->Relocations;
759 Reloc.Data.VirtualAddress += Fixup.getOffset();
761 TargetObjectWriter->getRelocType(Target, Fixup, CrossSection,
764 // FIXME: Can anyone explain what this does other than adjust for the size
766 if ((Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64 &&
767 Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32) ||
768 (Header.Machine == COFF::IMAGE_FILE_MACHINE_I386 &&
769 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32))
772 if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) {
773 switch (Reloc.Data.Type) {
774 case COFF::IMAGE_REL_ARM_ABSOLUTE:
775 case COFF::IMAGE_REL_ARM_ADDR32:
776 case COFF::IMAGE_REL_ARM_ADDR32NB:
777 case COFF::IMAGE_REL_ARM_TOKEN:
778 case COFF::IMAGE_REL_ARM_SECTION:
779 case COFF::IMAGE_REL_ARM_SECREL:
781 case COFF::IMAGE_REL_ARM_BRANCH11:
782 case COFF::IMAGE_REL_ARM_BLX11:
783 // IMAGE_REL_ARM_BRANCH11 and IMAGE_REL_ARM_BLX11 are only used for
784 // pre-ARMv7, which implicitly rules it out of ARMNT (it would be valid
786 case COFF::IMAGE_REL_ARM_BRANCH24:
787 case COFF::IMAGE_REL_ARM_BLX24:
788 case COFF::IMAGE_REL_ARM_MOV32A:
789 // IMAGE_REL_ARM_BRANCH24, IMAGE_REL_ARM_BLX24, IMAGE_REL_ARM_MOV32A are
790 // only used for ARM mode code, which is documented as being unsupported
791 // by Windows on ARM. Empirical proof indicates that masm is able to
792 // generate the relocations however the rest of the MSVC toolchain is
793 // unable to handle it.
794 llvm_unreachable("unsupported relocation");
796 case COFF::IMAGE_REL_ARM_MOV32T:
798 case COFF::IMAGE_REL_ARM_BRANCH20T:
799 case COFF::IMAGE_REL_ARM_BRANCH24T:
800 case COFF::IMAGE_REL_ARM_BLX23T:
801 // IMAGE_REL_BRANCH20T, IMAGE_REL_ARM_BRANCH24T, IMAGE_REL_ARM_BLX23T all
802 // perform a 4 byte adjustment to the relocation. Relative branches are
803 // offset by 4 on ARM, however, because there is no RELA relocations, all
804 // branches are offset by 4.
805 FixedValue = FixedValue + 4;
810 if (TargetObjectWriter->recordRelocation(Fixup))
811 coff_section->Relocations.push_back(Reloc);
814 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
815 const MCAsmLayout &Layout) {
816 size_t SectionsSize = Sections.size();
817 if (SectionsSize > static_cast<size_t>(INT32_MAX))
819 "PE COFF object files can't have more than 2147483647 sections");
821 // Assign symbol and section indexes and offsets.
822 int32_t NumberOfSections = static_cast<int32_t>(SectionsSize);
824 UseBigObj = NumberOfSections > COFF::MaxNumberOfSections16;
826 DenseMap<COFFSection *, int32_t> SectionIndices(
827 NextPowerOf2(NumberOfSections));
829 // Assign section numbers.
831 for (const auto &Section : Sections) {
832 SectionIndices[Section.get()] = Number;
833 Section->Number = Number;
834 Section->Symbol->Data.SectionNumber = Number;
835 Section->Symbol->Aux[0].Aux.SectionDefinition.Number = Number;
839 Header.NumberOfSections = NumberOfSections;
840 Header.NumberOfSymbols = 0;
842 for (auto FI = Asm.file_names_begin(), FE = Asm.file_names_end();
844 // round up to calculate the number of auxiliary symbols required
845 unsigned SymbolSize = UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size;
846 unsigned Count = (FI->size() + SymbolSize - 1) / SymbolSize;
848 COFFSymbol *file = createSymbol(".file");
849 file->Data.SectionNumber = COFF::IMAGE_SYM_DEBUG;
850 file->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE;
851 file->Aux.resize(Count);
854 unsigned Length = FI->size();
855 for (auto &Aux : file->Aux) {
856 Aux.AuxType = ATFile;
858 if (Length > SymbolSize) {
859 memcpy(&Aux.Aux, FI->c_str() + Offset, SymbolSize);
860 Length = Length - SymbolSize;
862 memcpy(&Aux.Aux, FI->c_str() + Offset, Length);
863 memset((char *)&Aux.Aux + Length, 0, SymbolSize - Length);
867 Offset += SymbolSize;
871 for (auto &Symbol : Symbols) {
872 // Update section number & offset for symbols that have them.
874 Symbol->Data.SectionNumber = Symbol->Section->Number;
875 if (Symbol->should_keep()) {
876 Symbol->Index = Header.NumberOfSymbols++;
877 // Update auxiliary symbol info.
878 Symbol->Data.NumberOfAuxSymbols = Symbol->Aux.size();
879 Header.NumberOfSymbols += Symbol->Data.NumberOfAuxSymbols;
884 // Build string table.
885 for (const auto &S : Sections)
886 if (S->Name.size() > COFF::NameSize)
887 Strings.add(S->Name);
888 for (const auto &S : Symbols)
889 if (S->should_keep() && S->Name.size() > COFF::NameSize)
890 Strings.add(S->Name);
891 Strings.finalize(StringTableBuilder::WinCOFF);
894 for (const auto &S : Sections)
896 for (auto &S : Symbols)
897 if (S->should_keep())
900 // Fixup weak external references.
901 for (auto &Symbol : Symbols) {
903 assert(Symbol->Index != -1);
904 assert(Symbol->Aux.size() == 1 && "Symbol must contain one aux symbol!");
905 assert(Symbol->Aux[0].AuxType == ATWeakExternal &&
906 "Symbol's aux symbol must be a Weak External!");
907 Symbol->Aux[0].Aux.WeakExternal.TagIndex = Symbol->Other->Index;
911 // Fixup associative COMDAT sections.
912 for (auto &Section : Sections) {
913 if (Section->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
914 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
917 const MCSectionCOFF &MCSec =
918 static_cast<const MCSectionCOFF &>(Section->MCData->getSection());
920 const MCSymbol *COMDAT = MCSec.getCOMDATSymbol();
922 COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(COMDAT);
923 assert(COMDATSymbol);
924 COFFSection *Assoc = COMDATSymbol->Section;
927 Twine("Missing associated COMDAT section for section ") +
928 MCSec.getSectionName());
930 // Skip this section if the associated section is unused.
931 if (Assoc->Number == -1)
934 Section->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
938 // Assign file offsets to COFF object file structures.
943 offset += COFF::Header32Size;
945 offset += COFF::Header16Size;
946 offset += COFF::SectionSize * Header.NumberOfSections;
948 for (const auto &Section : Asm) {
949 COFFSection *Sec = SectionMap[&Section];
951 if (Sec->Number == -1)
954 Sec->Header.SizeOfRawData =
955 Layout.getSectionAddressSize(&Section.getSectionData());
957 if (IsPhysicalSection(Sec)) {
958 // Align the section data to a four byte boundary.
959 offset = RoundUpToAlignment(offset, 4);
960 Sec->Header.PointerToRawData = offset;
962 offset += Sec->Header.SizeOfRawData;
965 if (Sec->Relocations.size() > 0) {
966 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
968 if (RelocationsOverflow) {
969 // Signal overflow by setting NumberOfRelocations to max value. Actual
970 // size is found in reloc #0. Microsoft tools understand this.
971 Sec->Header.NumberOfRelocations = 0xffff;
973 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
975 Sec->Header.PointerToRelocations = offset;
977 if (RelocationsOverflow) {
978 // Reloc #0 will contain actual count, so make room for it.
979 offset += COFF::RelocationSize;
982 offset += COFF::RelocationSize * Sec->Relocations.size();
984 for (auto &Relocation : Sec->Relocations) {
985 assert(Relocation.Symb->Index != -1);
986 Relocation.Data.SymbolTableIndex = Relocation.Symb->Index;
990 assert(Sec->Symbol->Aux.size() == 1 &&
991 "Section's symbol must have one aux!");
992 AuxSymbol &Aux = Sec->Symbol->Aux[0];
993 assert(Aux.AuxType == ATSectionDefinition &&
994 "Section's symbol's aux symbol must be a Section Definition!");
995 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
996 Aux.Aux.SectionDefinition.NumberOfRelocations =
997 Sec->Header.NumberOfRelocations;
998 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
999 Sec->Header.NumberOfLineNumbers;
1002 Header.PointerToSymbolTable = offset;
1004 // We want a deterministic output. It looks like GNU as also writes 0 in here.
1005 Header.TimeDateStamp = 0;
1007 // Write it all to disk...
1008 WriteFileHeader(Header);
1011 sections::iterator i, ie;
1012 MCAssembler::const_iterator j, je;
1014 for (auto &Section : Sections) {
1015 if (Section->Number != -1) {
1016 if (Section->Relocations.size() >= 0xffff)
1017 Section->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
1018 WriteSectionHeader(Section->Header);
1022 for (i = Sections.begin(), ie = Sections.end(),
1023 j = Asm.begin(), je = Asm.end();
1024 (i != ie) && (j != je); ++i, ++j) {
1026 if ((*i)->Number == -1)
1029 if ((*i)->Header.PointerToRawData != 0) {
1030 assert(OS.tell() <= (*i)->Header.PointerToRawData &&
1031 "Section::PointerToRawData is insane!");
1033 unsigned SectionDataPadding = (*i)->Header.PointerToRawData - OS.tell();
1034 assert(SectionDataPadding < 4 &&
1035 "Should only need at most three bytes of padding!");
1037 WriteZeros(SectionDataPadding);
1039 Asm.writeSectionData(&j->getSectionData(), Layout);
1042 if ((*i)->Relocations.size() > 0) {
1043 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
1044 "Section::PointerToRelocations is insane!");
1046 if ((*i)->Relocations.size() >= 0xffff) {
1047 // In case of overflow, write actual relocation count as first
1048 // relocation. Including the synthetic reloc itself (+ 1).
1050 r.VirtualAddress = (*i)->Relocations.size() + 1;
1051 r.SymbolTableIndex = 0;
1056 for (const auto &Relocation : (*i)->Relocations)
1057 WriteRelocation(Relocation.Data);
1059 assert((*i)->Header.PointerToRelocations == 0 &&
1060 "Section::PointerToRelocations is insane!");
1064 assert(OS.tell() == Header.PointerToSymbolTable &&
1065 "Header::PointerToSymbolTable is insane!");
1067 for (auto &Symbol : Symbols)
1068 if (Symbol->Index != -1)
1069 WriteSymbol(*Symbol);
1071 OS.write(Strings.data().data(), Strings.data().size());
1074 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :
1078 // Pin the vtable to this file.
1079 void MCWinCOFFObjectTargetWriter::anchor() {}
1081 //------------------------------------------------------------------------------
1082 // WinCOFFObjectWriter factory function
1085 llvm::createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
1086 raw_pwrite_stream &OS) {
1087 return new WinCOFFObjectWriter(MOTW, OS);