1//===- llvm/MC/WinCOFFObjectWriter.cpp ------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains an implementation of a Win32 COFF object file writer.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/ADT/DenseMap.h"
14#include "llvm/ADT/DenseSet.h"
15#include "llvm/ADT/STLExtras.h"
16#include "llvm/ADT/SmallString.h"
17#include "llvm/ADT/SmallVector.h"
18#include "llvm/ADT/StringRef.h"
19#include "llvm/ADT/Twine.h"
20#include "llvm/BinaryFormat/COFF.h"
21#include "llvm/MC/MCAssembler.h"
22#include "llvm/MC/MCContext.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCFixup.h"
25#include "llvm/MC/MCObjectWriter.h"
26#include "llvm/MC/MCSection.h"
27#include "llvm/MC/MCSectionCOFF.h"
28#include "llvm/MC/MCSymbol.h"
29#include "llvm/MC/MCSymbolCOFF.h"
30#include "llvm/MC/MCValue.h"
31#include "llvm/MC/MCWinCOFFObjectWriter.h"
32#include "llvm/MC/StringTableBuilder.h"
33#include "llvm/Support/CRC.h"
34#include "llvm/Support/Casting.h"
35#include "llvm/Support/EndianStream.h"
36#include "llvm/Support/ErrorHandling.h"
37#include "llvm/Support/LEB128.h"
38#include "llvm/Support/MathExtras.h"
39#include "llvm/Support/raw_ostream.h"
40#include <cassert>
41#include <cstdint>
42#include <cstring>
43#include <ctime>
44#include <memory>
45#include <string>
46#include <vector>
47
48using namespace llvm;
49using llvm::support::endian::write32le;
50
51#define DEBUG_TYPE "WinCOFFObjectWriter"
52
53namespace {
54
55constexpr int OffsetLabelIntervalBits = 20;
56
57using name = SmallString<COFF::NameSize>;
58
59enum AuxiliaryType { ATWeakExternal, ATFile, ATSectionDefinition };
60
61struct AuxSymbol {
62 AuxiliaryType AuxType;
63 COFF::Auxiliary Aux;
64};
65
66class COFFSection;
67
68class COFFSymbol {
69public:
70 COFF::symbol Data = {};
71
72 using AuxiliarySymbols = SmallVector<AuxSymbol, 1>;
73
74 name Name;
75 int Index = 0;
76 AuxiliarySymbols Aux;
77 COFFSymbol *Other = nullptr;
78 COFFSection *Section = nullptr;
79 int Relocations = 0;
80 const MCSymbol *MC = nullptr;
81
82 COFFSymbol(StringRef Name) : Name(Name) {}
83
84 void set_name_offset(uint32_t Offset);
85
86 int64_t getIndex() const { return Index; }
87 void setIndex(int Value) {
88 Index = Value;
89 if (MC)
90 MC->setIndex(static_cast<uint32_t>(Value));
91 }
92};
93
94// This class contains staging data for a COFF relocation entry.
95struct COFFRelocation {
96 COFF::relocation Data;
97 COFFSymbol *Symb = nullptr;
98
99 COFFRelocation() = default;
100
101 static size_t size() { return COFF::RelocationSize; }
102};
103
104using relocations = std::vector<COFFRelocation>;
105
106class COFFSection {
107public:
108 COFF::section Header = {};
109
110 std::string Name;
111 int Number = 0;
112 MCSectionCOFF const *MCSection = nullptr;
113 COFFSymbol *Symbol = nullptr;
114 relocations Relocations;
115
116 COFFSection(StringRef Name) : Name(std::string(Name)) {}
117
118 SmallVector<COFFSymbol *, 1> OffsetSymbols;
119};
120} // namespace
121
122class llvm::WinCOFFWriter {
123 WinCOFFObjectWriter &OWriter;
124 support::endian::Writer W;
125 MCAssembler *Asm = nullptr;
126
127 using symbols = std::vector<std::unique_ptr<COFFSymbol>>;
128 using sections = std::vector<std::unique_ptr<COFFSection>>;
129
130 using symbol_map = DenseMap<MCSymbol const *, COFFSymbol *>;
131 using section_map = DenseMap<MCSection const *, COFFSection *>;
132
133 using symbol_list = DenseSet<COFFSymbol *>;
134
135 // Root level file contents.
136 COFF::header Header = {};
137 sections Sections;
138 symbols Symbols;
139 StringTableBuilder Strings{StringTableBuilder::WinCOFF};
140
141 // Maps used during object file creation.
142 section_map SectionMap;
143 symbol_map SymbolMap;
144
145 symbol_list WeakDefaults;
146
147 bool UseBigObj;
148 bool UseOffsetLabels = false;
149
150public:
151 enum DwoMode {
152 AllSections,
153 NonDwoOnly,
154 DwoOnly,
155 } Mode;
156
157 WinCOFFWriter(WinCOFFObjectWriter &OWriter, raw_pwrite_stream &OS,
158 DwoMode Mode);
159
160 void reset();
161 void setAssembler(MCAssembler *A) { Asm = A; }
162 void executePostLayoutBinding();
163 void recordRelocation(const MCFragment &F, const MCFixup &Fixup,
164 MCValue Target, uint64_t &FixedValue);
165 uint64_t writeObject();
166 int getSectionNumber(const MCSection &Section) const;
167
168private:
169 MCContext &getContext() const { return OWriter.getContext(); }
170 COFFSymbol *createSymbol(StringRef Name);
171 COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol *Symbol);
172 COFFSection *createSection(StringRef Name);
173
174 void defineSection(MCSectionCOFF const &Sec);
175
176 COFFSymbol *getLinkedSymbol(const MCSymbol &Symbol);
177 void defineSymbol(const MCSymbol &Symbol);
178
179 void SetSymbolName(COFFSymbol &S);
180 void SetSectionName(COFFSection &S);
181
182 bool IsPhysicalSection(COFFSection *S);
183
184 // Entity writing methods.
185 void WriteFileHeader(const COFF::header &Header);
186 void WriteSymbol(const COFFSymbol &S);
187 void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
188 void writeSectionHeaders();
189 void WriteRelocation(const COFF::relocation &R);
190 uint32_t writeSectionContents(const MCSection &MCSec);
191 void writeSection(const COFFSection &Sec);
192
193 void createFileSymbols();
194 void setWeakDefaultNames();
195 void assignSectionNumbers();
196 void assignFileOffsets();
197};
198
199WinCOFFObjectWriter::WinCOFFObjectWriter(
200 std::unique_ptr<MCWinCOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS)
201 : TargetObjectWriter(std::move(MOTW)),
202 ObjWriter(std::make_unique<WinCOFFWriter>(args&: *this, args&: OS,
203 args: WinCOFFWriter::AllSections)) {}
204WinCOFFObjectWriter::WinCOFFObjectWriter(
205 std::unique_ptr<MCWinCOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS,
206 raw_pwrite_stream &DwoOS)
207 : TargetObjectWriter(std::move(MOTW)),
208 ObjWriter(std::make_unique<WinCOFFWriter>(args&: *this, args&: OS,
209 args: WinCOFFWriter::NonDwoOnly)),
210 DwoWriter(std::make_unique<WinCOFFWriter>(args&: *this, args&: DwoOS,
211 args: WinCOFFWriter::DwoOnly)) {}
212
213static bool isDwoSection(const MCSection &Sec) {
214 return Sec.getName().ends_with(Suffix: ".dwo");
215}
216
217//------------------------------------------------------------------------------
218// Symbol class implementation
219
220// In the case that the name does not fit within 8 bytes, the offset
221// into the string table is stored in the last 4 bytes instead, leaving
222// the first 4 bytes as 0.
223void COFFSymbol::set_name_offset(uint32_t Offset) {
224 write32le(P: Data.Name + 0, V: 0);
225 write32le(P: Data.Name + 4, V: Offset);
226}
227
228//------------------------------------------------------------------------------
229// WinCOFFWriter class implementation
230
231WinCOFFWriter::WinCOFFWriter(WinCOFFObjectWriter &OWriter,
232 raw_pwrite_stream &OS, DwoMode Mode)
233 : OWriter(OWriter), W(OS, llvm::endianness::little), Mode(Mode) {
234 Header.Machine = OWriter.TargetObjectWriter->getMachine();
235 // Some relocations on ARM64 (the 21 bit ADRP relocations) have a slightly
236 // limited range for the immediate offset (+/- 1 MB); create extra offset
237 // label symbols with regular intervals to allow referencing a
238 // non-temporary symbol that is close enough.
239 UseOffsetLabels = COFF::isAnyArm64(Machine: Header.Machine);
240}
241
242COFFSymbol *WinCOFFWriter::createSymbol(StringRef Name) {
243 Symbols.push_back(x: std::make_unique<COFFSymbol>(args&: Name));
244 return Symbols.back().get();
245}
246
247COFFSymbol *WinCOFFWriter::GetOrCreateCOFFSymbol(const MCSymbol *Symbol) {
248 COFFSymbol *&Ret = SymbolMap[Symbol];
249 if (!Ret)
250 Ret = createSymbol(Name: Symbol->getName());
251 return Ret;
252}
253
254COFFSection *WinCOFFWriter::createSection(StringRef Name) {
255 Sections.emplace_back(args: std::make_unique<COFFSection>(args&: Name));
256 return Sections.back().get();
257}
258
259static uint32_t getAlignment(const MCSectionCOFF &Sec) {
260 switch (Sec.getAlign().value()) {
261 case 1:
262 return COFF::IMAGE_SCN_ALIGN_1BYTES;
263 case 2:
264 return COFF::IMAGE_SCN_ALIGN_2BYTES;
265 case 4:
266 return COFF::IMAGE_SCN_ALIGN_4BYTES;
267 case 8:
268 return COFF::IMAGE_SCN_ALIGN_8BYTES;
269 case 16:
270 return COFF::IMAGE_SCN_ALIGN_16BYTES;
271 case 32:
272 return COFF::IMAGE_SCN_ALIGN_32BYTES;
273 case 64:
274 return COFF::IMAGE_SCN_ALIGN_64BYTES;
275 case 128:
276 return COFF::IMAGE_SCN_ALIGN_128BYTES;
277 case 256:
278 return COFF::IMAGE_SCN_ALIGN_256BYTES;
279 case 512:
280 return COFF::IMAGE_SCN_ALIGN_512BYTES;
281 case 1024:
282 return COFF::IMAGE_SCN_ALIGN_1024BYTES;
283 case 2048:
284 return COFF::IMAGE_SCN_ALIGN_2048BYTES;
285 case 4096:
286 return COFF::IMAGE_SCN_ALIGN_4096BYTES;
287 case 8192:
288 return COFF::IMAGE_SCN_ALIGN_8192BYTES;
289 }
290 llvm_unreachable("unsupported section alignment");
291}
292
293/// This function takes a section data object from the assembler
294/// and creates the associated COFF section staging object.
295void WinCOFFWriter::defineSection(const MCSectionCOFF &MCSec) {
296 COFFSection *Section = createSection(Name: MCSec.getName());
297 COFFSymbol *Symbol = createSymbol(Name: MCSec.getName());
298 Section->Symbol = Symbol;
299 SymbolMap[MCSec.getBeginSymbol()] = Symbol;
300 Symbol->Section = Section;
301 Symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
302
303 // Create a COMDAT symbol if needed.
304 if (MCSec.getSelection() != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
305 if (const MCSymbol *S = MCSec.getCOMDATSymbol()) {
306 COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(Symbol: S);
307 if (COMDATSymbol->Section)
308 report_fatal_error(reason: "two sections have the same comdat");
309 COMDATSymbol->Section = Section;
310 }
311 }
312
313 // In this case the auxiliary symbol is a Section Definition.
314 Symbol->Aux.resize(N: 1);
315 Symbol->Aux[0] = {};
316 Symbol->Aux[0].AuxType = ATSectionDefinition;
317 Symbol->Aux[0].Aux.SectionDefinition.Selection = MCSec.getSelection();
318
319 // Set section alignment.
320 Section->Header.Characteristics = MCSec.getCharacteristics();
321 Section->Header.Characteristics |= getAlignment(Sec: MCSec);
322
323 // Bind internal COFF section to MC section.
324 Section->MCSection = &MCSec;
325 SectionMap[&MCSec] = Section;
326
327 if (UseOffsetLabels) {
328 const uint32_t Interval = 1 << OffsetLabelIntervalBits;
329 uint32_t N = 1;
330 for (uint32_t Off = Interval, E = Asm->getSectionAddressSize(Sec: MCSec);
331 Off < E; Off += Interval) {
332 auto Name = ("$L" + MCSec.getName() + "_" + Twine(N++)).str();
333 COFFSymbol *Label = createSymbol(Name);
334 Label->Section = Section;
335 Label->Data.StorageClass = COFF::IMAGE_SYM_CLASS_LABEL;
336 Label->Data.Value = Off;
337 Section->OffsetSymbols.push_back(Elt: Label);
338 }
339 }
340}
341
342static uint64_t getSymbolValue(const MCSymbol &Symbol, const MCAssembler &Asm) {
343 if (Symbol.isCommon() && Symbol.isExternal())
344 return Symbol.getCommonSize();
345
346 uint64_t Res;
347 if (!Asm.getSymbolOffset(S: Symbol, Val&: Res))
348 return 0;
349
350 return Res;
351}
352
353COFFSymbol *WinCOFFWriter::getLinkedSymbol(const MCSymbol &Symbol) {
354 if (!Symbol.isVariable())
355 return nullptr;
356
357 const MCSymbolRefExpr *SymRef =
358 dyn_cast<MCSymbolRefExpr>(Val: Symbol.getVariableValue());
359 if (!SymRef)
360 return nullptr;
361
362 const MCSymbol &Aliasee = SymRef->getSymbol();
363 if (Aliasee.isUndefined() || Aliasee.isExternal())
364 return GetOrCreateCOFFSymbol(Symbol: &Aliasee);
365 else
366 return nullptr;
367}
368
369/// This function takes a symbol data object from the assembler
370/// and creates the associated COFF symbol staging object.
371void WinCOFFWriter::defineSymbol(const MCSymbol &MCSym) {
372 const MCSymbol *Base = Asm->getBaseSymbol(Symbol: MCSym);
373 COFFSection *Sec = nullptr;
374 MCSectionCOFF *MCSec = nullptr;
375 if (Base && Base->getFragment()) {
376 MCSec = cast<MCSectionCOFF>(Val: Base->getFragment()->getParent());
377 Sec = SectionMap[MCSec];
378 }
379
380 if (Mode == NonDwoOnly && MCSec && isDwoSection(Sec: *MCSec))
381 return;
382
383 COFFSymbol *Sym = GetOrCreateCOFFSymbol(Symbol: &MCSym);
384 COFFSymbol *Local = nullptr;
385 if (cast<MCSymbolCOFF>(Val: MCSym).getWeakExternalCharacteristics()) {
386 Sym->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
387 Sym->Section = nullptr;
388
389 COFFSymbol *WeakDefault = getLinkedSymbol(Symbol: MCSym);
390 if (!WeakDefault) {
391 std::string WeakName = (".weak." + MCSym.getName() + ".default").str();
392 WeakDefault = createSymbol(Name: WeakName);
393 if (!Sec)
394 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
395 else
396 WeakDefault->Section = Sec;
397 WeakDefaults.insert(V: WeakDefault);
398 Local = WeakDefault;
399 }
400
401 Sym->Other = WeakDefault;
402
403 // Setup the Weak External auxiliary symbol.
404 Sym->Aux.resize(N: 1);
405 memset(s: &Sym->Aux[0], c: 0, n: sizeof(Sym->Aux[0]));
406 Sym->Aux[0].AuxType = ATWeakExternal;
407 Sym->Aux[0].Aux.WeakExternal.TagIndex = 0; // Filled in later
408 Sym->Aux[0].Aux.WeakExternal.Characteristics =
409 cast<MCSymbolCOFF>(Val: MCSym).getWeakExternalCharacteristics();
410 } else {
411 if (!Base)
412 Sym->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
413 else
414 Sym->Section = Sec;
415 Local = Sym;
416 }
417
418 if (Local) {
419 Local->Data.Value = getSymbolValue(Symbol: MCSym, Asm: *Asm);
420
421 const MCSymbolCOFF &SymbolCOFF = cast<MCSymbolCOFF>(Val: MCSym);
422 Local->Data.Type = SymbolCOFF.getType();
423 Local->Data.StorageClass = SymbolCOFF.getClass();
424
425 // If no storage class was specified in the streamer, define it here.
426 if (Local->Data.StorageClass == COFF::IMAGE_SYM_CLASS_NULL) {
427 bool IsExternal =
428 MCSym.isExternal() || (!MCSym.getFragment() && !MCSym.isVariable());
429
430 Local->Data.StorageClass = IsExternal ? COFF::IMAGE_SYM_CLASS_EXTERNAL
431 : COFF::IMAGE_SYM_CLASS_STATIC;
432 }
433 }
434
435 Sym->MC = &MCSym;
436}
437
438void WinCOFFWriter::SetSectionName(COFFSection &S) {
439 if (S.Name.size() <= COFF::NameSize) {
440 std::memcpy(dest: S.Header.Name, src: S.Name.c_str(), n: S.Name.size());
441 return;
442 }
443
444 uint64_t StringTableEntry = Strings.getOffset(S: S.Name);
445 if (!COFF::encodeSectionName(Out: S.Header.Name, Offset: StringTableEntry))
446 report_fatal_error(reason: "COFF string table is greater than 64 GB.");
447}
448
449void WinCOFFWriter::SetSymbolName(COFFSymbol &S) {
450 if (S.Name.size() > COFF::NameSize)
451 S.set_name_offset(Strings.getOffset(S: S.Name));
452 else
453 std::memcpy(dest: S.Data.Name, src: S.Name.c_str(), n: S.Name.size());
454}
455
456bool WinCOFFWriter::IsPhysicalSection(COFFSection *S) {
457 return (S->Header.Characteristics & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) ==
458 0;
459}
460
461//------------------------------------------------------------------------------
462// entity writing methods
463
464void WinCOFFWriter::WriteFileHeader(const COFF::header &Header) {
465 if (UseBigObj) {
466 W.write<uint16_t>(Val: COFF::IMAGE_FILE_MACHINE_UNKNOWN);
467 W.write<uint16_t>(Val: 0xFFFF);
468 W.write<uint16_t>(Val: COFF::BigObjHeader::MinBigObjectVersion);
469 W.write<uint16_t>(Val: Header.Machine);
470 W.write<uint32_t>(Val: Header.TimeDateStamp);
471 W.OS.write(Ptr: COFF::BigObjMagic, Size: sizeof(COFF::BigObjMagic));
472 W.write<uint32_t>(Val: 0);
473 W.write<uint32_t>(Val: 0);
474 W.write<uint32_t>(Val: 0);
475 W.write<uint32_t>(Val: 0);
476 W.write<uint32_t>(Val: Header.NumberOfSections);
477 W.write<uint32_t>(Val: Header.PointerToSymbolTable);
478 W.write<uint32_t>(Val: Header.NumberOfSymbols);
479 } else {
480 W.write<uint16_t>(Val: Header.Machine);
481 W.write<uint16_t>(Val: static_cast<int16_t>(Header.NumberOfSections));
482 W.write<uint32_t>(Val: Header.TimeDateStamp);
483 W.write<uint32_t>(Val: Header.PointerToSymbolTable);
484 W.write<uint32_t>(Val: Header.NumberOfSymbols);
485 W.write<uint16_t>(Val: Header.SizeOfOptionalHeader);
486 W.write<uint16_t>(Val: Header.Characteristics);
487 }
488}
489
490void WinCOFFWriter::WriteSymbol(const COFFSymbol &S) {
491 W.OS.write(Ptr: S.Data.Name, Size: COFF::NameSize);
492 W.write<uint32_t>(Val: S.Data.Value);
493 if (UseBigObj)
494 W.write<uint32_t>(Val: S.Data.SectionNumber);
495 else
496 W.write<uint16_t>(Val: static_cast<int16_t>(S.Data.SectionNumber));
497 W.write<uint16_t>(Val: S.Data.Type);
498 W.OS << char(S.Data.StorageClass);
499 W.OS << char(S.Data.NumberOfAuxSymbols);
500 WriteAuxiliarySymbols(S: S.Aux);
501}
502
503void WinCOFFWriter::WriteAuxiliarySymbols(
504 const COFFSymbol::AuxiliarySymbols &S) {
505 for (const AuxSymbol &i : S) {
506 switch (i.AuxType) {
507 case ATWeakExternal:
508 W.write<uint32_t>(Val: i.Aux.WeakExternal.TagIndex);
509 W.write<uint32_t>(Val: i.Aux.WeakExternal.Characteristics);
510 W.OS.write_zeros(NumZeros: sizeof(i.Aux.WeakExternal.unused));
511 if (UseBigObj)
512 W.OS.write_zeros(NumZeros: COFF::Symbol32Size - COFF::Symbol16Size);
513 break;
514 case ATFile:
515 W.OS.write(Ptr: reinterpret_cast<const char *>(&i.Aux),
516 Size: UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size);
517 break;
518 case ATSectionDefinition:
519 W.write<uint32_t>(Val: i.Aux.SectionDefinition.Length);
520 W.write<uint16_t>(Val: i.Aux.SectionDefinition.NumberOfRelocations);
521 W.write<uint16_t>(Val: i.Aux.SectionDefinition.NumberOfLinenumbers);
522 W.write<uint32_t>(Val: i.Aux.SectionDefinition.CheckSum);
523 W.write<uint16_t>(Val: static_cast<int16_t>(i.Aux.SectionDefinition.Number));
524 W.OS << char(i.Aux.SectionDefinition.Selection);
525 W.OS.write_zeros(NumZeros: sizeof(i.Aux.SectionDefinition.unused));
526 W.write<uint16_t>(
527 Val: static_cast<int16_t>(i.Aux.SectionDefinition.Number >> 16));
528 if (UseBigObj)
529 W.OS.write_zeros(NumZeros: COFF::Symbol32Size - COFF::Symbol16Size);
530 break;
531 }
532 }
533}
534
535// Write the section header.
536void WinCOFFWriter::writeSectionHeaders() {
537 // Section numbers must be monotonically increasing in the section
538 // header, but our Sections array is not sorted by section number,
539 // so make a copy of Sections and sort it.
540 std::vector<COFFSection *> Arr;
541 for (auto &Section : Sections)
542 Arr.push_back(x: Section.get());
543 llvm::sort(C&: Arr, Comp: [](const COFFSection *A, const COFFSection *B) {
544 return A->Number < B->Number;
545 });
546
547 for (auto &Section : Arr) {
548 if (Section->Number == -1)
549 continue;
550
551 COFF::section &S = Section->Header;
552 if (Section->Relocations.size() >= 0xffff)
553 S.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
554 W.OS.write(Ptr: S.Name, Size: COFF::NameSize);
555 W.write<uint32_t>(Val: S.VirtualSize);
556 W.write<uint32_t>(Val: S.VirtualAddress);
557 W.write<uint32_t>(Val: S.SizeOfRawData);
558 W.write<uint32_t>(Val: S.PointerToRawData);
559 W.write<uint32_t>(Val: S.PointerToRelocations);
560 W.write<uint32_t>(Val: S.PointerToLineNumbers);
561 W.write<uint16_t>(Val: S.NumberOfRelocations);
562 W.write<uint16_t>(Val: S.NumberOfLineNumbers);
563 W.write<uint32_t>(Val: S.Characteristics);
564 }
565}
566
567void WinCOFFWriter::WriteRelocation(const COFF::relocation &R) {
568 W.write<uint32_t>(Val: R.VirtualAddress);
569 W.write<uint32_t>(Val: R.SymbolTableIndex);
570 W.write<uint16_t>(Val: R.Type);
571}
572
573// Write MCSec's contents. What this function does is essentially
574// "Asm.writeSectionData(&MCSec)", but it's a bit complicated
575// because it needs to compute a CRC.
576uint32_t WinCOFFWriter::writeSectionContents(const MCSection &MCSec) {
577 // Save the contents of the section to a temporary buffer, we need this
578 // to CRC the data before we dump it into the object file.
579 SmallVector<char, 128> Buf;
580 raw_svector_ostream VecOS(Buf);
581 Asm->writeSectionData(OS&: VecOS, Section: &MCSec);
582
583 // Write the section contents to the object file.
584 W.OS << Buf;
585
586 // Calculate our CRC with an initial value of '0', this is not how
587 // JamCRC is specified but it aligns with the expected output.
588 JamCRC JC(/*Init=*/0);
589 JC.update(Data: ArrayRef(reinterpret_cast<uint8_t *>(Buf.data()), Buf.size()));
590 return JC.getCRC();
591}
592
593void WinCOFFWriter::writeSection(const COFFSection &Sec) {
594 if (Sec.Number == -1)
595 return;
596
597 // Write the section contents.
598 if (Sec.Header.PointerToRawData != 0) {
599 assert(W.OS.tell() == Sec.Header.PointerToRawData &&
600 "Section::PointerToRawData is insane!");
601
602 uint32_t CRC = writeSectionContents(MCSec: *Sec.MCSection);
603
604 // Update the section definition auxiliary symbol to record the CRC.
605 COFFSymbol::AuxiliarySymbols &AuxSyms = Sec.Symbol->Aux;
606 assert(AuxSyms.size() == 1 && AuxSyms[0].AuxType == ATSectionDefinition);
607 AuxSymbol &SecDef = AuxSyms[0];
608 SecDef.Aux.SectionDefinition.CheckSum = CRC;
609 }
610
611 // Write relocations for this section.
612 if (Sec.Relocations.empty()) {
613 assert(Sec.Header.PointerToRelocations == 0 &&
614 "Section::PointerToRelocations is insane!");
615 return;
616 }
617
618 assert(W.OS.tell() == Sec.Header.PointerToRelocations &&
619 "Section::PointerToRelocations is insane!");
620
621 if (Sec.Relocations.size() >= 0xffff) {
622 // In case of overflow, write actual relocation count as first
623 // relocation. Including the synthetic reloc itself (+ 1).
624 COFF::relocation R;
625 R.VirtualAddress = Sec.Relocations.size() + 1;
626 R.SymbolTableIndex = 0;
627 R.Type = 0;
628 WriteRelocation(R);
629 }
630
631 for (const auto &Relocation : Sec.Relocations)
632 WriteRelocation(R: Relocation.Data);
633}
634
635// Create .file symbols.
636void WinCOFFWriter::createFileSymbols() {
637 for (const std::pair<std::string, size_t> &It : OWriter.getFileNames()) {
638 // round up to calculate the number of auxiliary symbols required
639 const std::string &Name = It.first;
640 unsigned SymbolSize = UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size;
641 unsigned Count = (Name.size() + SymbolSize - 1) / SymbolSize;
642
643 COFFSymbol *File = createSymbol(Name: ".file");
644 File->Data.SectionNumber = COFF::IMAGE_SYM_DEBUG;
645 File->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE;
646 File->Aux.resize(N: Count);
647
648 unsigned Offset = 0;
649 unsigned Length = Name.size();
650 for (auto &Aux : File->Aux) {
651 Aux.AuxType = ATFile;
652
653 if (Length > SymbolSize) {
654 memcpy(dest: &Aux.Aux, src: Name.c_str() + Offset, n: SymbolSize);
655 Length = Length - SymbolSize;
656 } else {
657 memcpy(dest: &Aux.Aux, src: Name.c_str() + Offset, n: Length);
658 memset(s: (char *)&Aux.Aux + Length, c: 0, n: SymbolSize - Length);
659 break;
660 }
661
662 Offset += SymbolSize;
663 }
664 }
665}
666
667void WinCOFFWriter::setWeakDefaultNames() {
668 if (WeakDefaults.empty())
669 return;
670
671 // If multiple object files use a weak symbol (either with a regular
672 // defined default, or an absolute zero symbol as default), the defaults
673 // cause duplicate definitions unless their names are made unique. Look
674 // for a defined extern symbol, that isn't comdat - that should be unique
675 // unless there are other duplicate definitions. And if none is found,
676 // allow picking a comdat symbol, as that's still better than nothing.
677
678 COFFSymbol *Unique = nullptr;
679 for (bool AllowComdat : {false, true}) {
680 for (auto &Sym : Symbols) {
681 // Don't include the names of the defaults themselves
682 if (WeakDefaults.count(V: Sym.get()))
683 continue;
684 // Only consider external symbols
685 if (Sym->Data.StorageClass != COFF::IMAGE_SYM_CLASS_EXTERNAL)
686 continue;
687 // Only consider symbols defined in a section or that are absolute
688 if (!Sym->Section && Sym->Data.SectionNumber != COFF::IMAGE_SYM_ABSOLUTE)
689 continue;
690 if (!AllowComdat && Sym->Section &&
691 Sym->Section->Header.Characteristics & COFF::IMAGE_SCN_LNK_COMDAT)
692 continue;
693 Unique = Sym.get();
694 break;
695 }
696 if (Unique)
697 break;
698 }
699 // If we didn't find any unique symbol to use for the names, just skip this.
700 if (!Unique)
701 return;
702 for (auto *Sym : WeakDefaults) {
703 Sym->Name.append(RHS: ".");
704 Sym->Name.append(RHS: Unique->Name);
705 }
706}
707
708static bool isAssociative(const COFFSection &Section) {
709 return Section.Symbol->Aux[0].Aux.SectionDefinition.Selection ==
710 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
711}
712
713void WinCOFFWriter::assignSectionNumbers() {
714 size_t I = 1;
715 auto Assign = [&](COFFSection &Section) {
716 Section.Number = I;
717 Section.Symbol->Data.SectionNumber = I;
718 Section.Symbol->Aux[0].Aux.SectionDefinition.Number = I;
719 ++I;
720 };
721
722 // Although it is not explicitly requested by the Microsoft COFF spec,
723 // we should avoid emitting forward associative section references,
724 // because MSVC link.exe as of 2017 cannot handle that.
725 for (const std::unique_ptr<COFFSection> &Section : Sections)
726 if (!isAssociative(Section: *Section))
727 Assign(*Section);
728 for (const std::unique_ptr<COFFSection> &Section : Sections)
729 if (isAssociative(Section: *Section))
730 Assign(*Section);
731}
732
733// Assign file offsets to COFF object file structures.
734void WinCOFFWriter::assignFileOffsets() {
735 unsigned Offset = W.OS.tell();
736
737 Offset += UseBigObj ? COFF::Header32Size : COFF::Header16Size;
738 Offset += COFF::SectionSize * Header.NumberOfSections;
739
740 for (const auto &Section : *Asm) {
741 COFFSection *Sec = SectionMap[&Section];
742
743 if (!Sec || Sec->Number == -1)
744 continue;
745
746 Sec->Header.SizeOfRawData = Asm->getSectionAddressSize(Sec: Section);
747
748 if (IsPhysicalSection(S: Sec)) {
749 Sec->Header.PointerToRawData = Offset;
750 Offset += Sec->Header.SizeOfRawData;
751 }
752
753 if (!Sec->Relocations.empty()) {
754 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
755
756 if (RelocationsOverflow) {
757 // Signal overflow by setting NumberOfRelocations to max value. Actual
758 // size is found in reloc #0. Microsoft tools understand this.
759 Sec->Header.NumberOfRelocations = 0xffff;
760 } else {
761 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
762 }
763 Sec->Header.PointerToRelocations = Offset;
764
765 if (RelocationsOverflow) {
766 // Reloc #0 will contain actual count, so make room for it.
767 Offset += COFF::RelocationSize;
768 }
769
770 Offset += COFF::RelocationSize * Sec->Relocations.size();
771
772 for (auto &Relocation : Sec->Relocations) {
773 assert(Relocation.Symb->getIndex() != -1);
774 if (Header.Machine != COFF::IMAGE_FILE_MACHINE_R4000 ||
775 Relocation.Data.Type != COFF::IMAGE_REL_MIPS_PAIR) {
776 Relocation.Data.SymbolTableIndex = Relocation.Symb->getIndex();
777 }
778 }
779 }
780
781 assert(Sec->Symbol->Aux.size() == 1 &&
782 "Section's symbol must have one aux!");
783 AuxSymbol &Aux = Sec->Symbol->Aux[0];
784 assert(Aux.AuxType == ATSectionDefinition &&
785 "Section's symbol's aux symbol must be a Section Definition!");
786 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
787 Aux.Aux.SectionDefinition.NumberOfRelocations =
788 Sec->Header.NumberOfRelocations;
789 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
790 Sec->Header.NumberOfLineNumbers;
791 }
792
793 Header.PointerToSymbolTable = Offset;
794}
795
796void WinCOFFWriter::reset() {
797 memset(s: &Header, c: 0, n: sizeof(Header));
798 Header.Machine = OWriter.TargetObjectWriter->getMachine();
799 Sections.clear();
800 Symbols.clear();
801 Strings.clear();
802 SectionMap.clear();
803 SymbolMap.clear();
804 WeakDefaults.clear();
805}
806
807void WinCOFFWriter::executePostLayoutBinding() {
808 // "Define" each section & symbol. This creates section & symbol
809 // entries in the staging area.
810 for (const auto &Section : *Asm) {
811 if ((Mode == NonDwoOnly && isDwoSection(Sec: Section)) ||
812 (Mode == DwoOnly && !isDwoSection(Sec: Section)))
813 continue;
814 defineSection(MCSec: static_cast<const MCSectionCOFF &>(Section));
815 }
816
817 if (Mode != DwoOnly)
818 for (const MCSymbol &Symbol : Asm->symbols())
819 // Define non-temporary or temporary static (private-linkage) symbols
820 if (!Symbol.isTemporary() ||
821 cast<MCSymbolCOFF>(Val: Symbol).getClass() == COFF::IMAGE_SYM_CLASS_STATIC)
822 defineSymbol(MCSym: Symbol);
823
824 UseBigObj = Sections.size() > COFF::MaxNumberOfSections16;
825 Header.NumberOfSections = Sections.size();
826 Header.NumberOfSymbols = 0;
827 if (Sections.size() > INT32_MAX)
828 report_fatal_error(
829 reason: "PE COFF object files can't have more than 2147483647 sections");
830
831 assignSectionNumbers();
832}
833
834void WinCOFFWriter::recordRelocation(const MCFragment &F, const MCFixup &Fixup,
835 MCValue Target, uint64_t &FixedValue) {
836 assert(Target.getAddSym() && "Relocation must reference a symbol!");
837
838 const MCSymbol &A = *Target.getAddSym();
839 if (!A.isRegistered()) {
840 getContext().reportError(L: Fixup.getLoc(), Msg: Twine("symbol '") + A.getName() +
841 "' can not be undefined");
842 return;
843 }
844 if (A.isTemporary() && A.isUndefined()) {
845 getContext().reportError(L: Fixup.getLoc(), Msg: Twine("assembler label '") +
846 A.getName() +
847 "' can not be undefined");
848 return;
849 }
850
851 MCSection *MCSec = F.getParent();
852
853 // Mark this symbol as requiring an entry in the symbol table.
854 assert(SectionMap.contains(MCSec) &&
855 "Section must already have been defined in executePostLayoutBinding!");
856
857 COFFSection *Sec = SectionMap[MCSec];
858 if (const MCSymbol *B = Target.getSubSym()) {
859 if (!B->getFragment()) {
860 getContext().reportError(
861 L: Fixup.getLoc(),
862 Msg: Twine("symbol '") + B->getName() +
863 "' can not be undefined in a subtraction expression");
864 return;
865 }
866
867 // Offset of the symbol in the section
868 int64_t OffsetOfB = Asm->getSymbolOffset(S: *B);
869
870 // Offset of the relocation in the section
871 int64_t OffsetOfRelocation = Asm->getFragmentOffset(F) + Fixup.getOffset();
872
873 FixedValue = (OffsetOfRelocation - OffsetOfB) + Target.getConstant();
874 } else {
875 FixedValue = Target.getConstant();
876 }
877
878 COFFRelocation Reloc;
879
880 Reloc.Data.SymbolTableIndex = 0;
881 Reloc.Data.VirtualAddress = Asm->getFragmentOffset(F);
882
883 // Turn relocations for temporary symbols into section relocations.
884 if (A.isTemporary() && !SymbolMap[&A]) {
885 MCSection *TargetSection = &A.getSection();
886 assert(
887 SectionMap.contains(TargetSection) &&
888 "Section must already have been defined in executePostLayoutBinding!");
889 COFFSection *Section = SectionMap[TargetSection];
890 Reloc.Symb = Section->Symbol;
891 FixedValue += Asm->getSymbolOffset(S: A);
892 // Technically, we should do the final adjustments of FixedValue (below)
893 // before picking an offset symbol, otherwise we might choose one which
894 // is slightly too far away. The relocations where it really matters
895 // (arm64 adrp relocations) don't get any offset though.
896 if (UseOffsetLabels && !Section->OffsetSymbols.empty()) {
897 uint64_t LabelIndex = FixedValue >> OffsetLabelIntervalBits;
898 if (LabelIndex > 0) {
899 if (LabelIndex <= Section->OffsetSymbols.size())
900 Reloc.Symb = Section->OffsetSymbols[LabelIndex - 1];
901 else
902 Reloc.Symb = Section->OffsetSymbols.back();
903 FixedValue -= Reloc.Symb->Data.Value;
904 }
905 }
906 } else {
907 assert(
908 SymbolMap.contains(&A) &&
909 "Symbol must already have been defined in executePostLayoutBinding!");
910 Reloc.Symb = SymbolMap[&A];
911 }
912
913 ++Reloc.Symb->Relocations;
914
915 Reloc.Data.VirtualAddress += Fixup.getOffset();
916 Reloc.Data.Type = OWriter.TargetObjectWriter->getRelocType(
917 Ctx&: getContext(), Target, Fixup, IsCrossSection: Target.getSubSym(), MAB: Asm->getBackend());
918
919 // The *_REL32 relocations are relative to the end of the relocation,
920 // not to the start.
921 if ((Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64 &&
922 Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32) ||
923 (Header.Machine == COFF::IMAGE_FILE_MACHINE_I386 &&
924 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32) ||
925 (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT &&
926 Reloc.Data.Type == COFF::IMAGE_REL_ARM_REL32) ||
927 (COFF::isAnyArm64(Machine: Header.Machine) &&
928 Reloc.Data.Type == COFF::IMAGE_REL_ARM64_REL32))
929 FixedValue += 4;
930
931 if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) {
932 switch (Reloc.Data.Type) {
933 case COFF::IMAGE_REL_ARM_ABSOLUTE:
934 case COFF::IMAGE_REL_ARM_ADDR32:
935 case COFF::IMAGE_REL_ARM_ADDR32NB:
936 case COFF::IMAGE_REL_ARM_TOKEN:
937 case COFF::IMAGE_REL_ARM_SECTION:
938 case COFF::IMAGE_REL_ARM_SECREL:
939 break;
940 case COFF::IMAGE_REL_ARM_BRANCH11:
941 case COFF::IMAGE_REL_ARM_BLX11:
942 // IMAGE_REL_ARM_BRANCH11 and IMAGE_REL_ARM_BLX11 are only used for
943 // pre-ARMv7, which implicitly rules it out of ARMNT (it would be valid
944 // for Windows CE).
945 case COFF::IMAGE_REL_ARM_BRANCH24:
946 case COFF::IMAGE_REL_ARM_BLX24:
947 case COFF::IMAGE_REL_ARM_MOV32A:
948 // IMAGE_REL_ARM_BRANCH24, IMAGE_REL_ARM_BLX24, IMAGE_REL_ARM_MOV32A are
949 // only used for ARM mode code, which is documented as being unsupported
950 // by Windows on ARM. Empirical proof indicates that masm is able to
951 // generate the relocations however the rest of the MSVC toolchain is
952 // unable to handle it.
953 llvm_unreachable("unsupported relocation");
954 break;
955 case COFF::IMAGE_REL_ARM_MOV32T:
956 break;
957 case COFF::IMAGE_REL_ARM_BRANCH20T:
958 case COFF::IMAGE_REL_ARM_BRANCH24T:
959 case COFF::IMAGE_REL_ARM_BLX23T:
960 // IMAGE_REL_BRANCH20T, IMAGE_REL_ARM_BRANCH24T, IMAGE_REL_ARM_BLX23T all
961 // perform a 4 byte adjustment to the relocation. Relative branches are
962 // offset by 4 on ARM, however, because there is no RELA relocations, all
963 // branches are offset by 4.
964 FixedValue = FixedValue + 4;
965 break;
966 }
967 }
968
969 // The fixed value never makes sense for section indices, ignore it.
970 if (Fixup.getKind() == FK_SecRel_2)
971 FixedValue = 0;
972
973 if (OWriter.TargetObjectWriter->recordRelocation(Fixup)) {
974 Sec->Relocations.push_back(x: Reloc);
975 if (Header.Machine == COFF::IMAGE_FILE_MACHINE_R4000 &&
976 (Reloc.Data.Type == COFF::IMAGE_REL_MIPS_REFHI ||
977 Reloc.Data.Type == COFF::IMAGE_REL_MIPS_SECRELHI)) {
978 // IMAGE_REL_MIPS_REFHI and IMAGE_REL_MIPS_SECRELHI *must*
979 // be followed by IMAGE_REL_MIPS_PAIR
980 auto RelocPair = Reloc;
981 RelocPair.Data.Type = COFF::IMAGE_REL_MIPS_PAIR;
982 Sec->Relocations.push_back(x: RelocPair);
983 }
984 }
985}
986
987static std::time_t getTime() {
988 std::time_t Now = time(timer: nullptr);
989 if (Now < 0 || !isUInt<32>(x: Now))
990 return UINT32_MAX;
991 return Now;
992}
993
994uint64_t WinCOFFWriter::writeObject() {
995 uint64_t StartOffset = W.OS.tell();
996
997 setWeakDefaultNames();
998 if (Mode != DwoOnly)
999 createFileSymbols();
1000
1001 for (auto &Symbol : Symbols) {
1002 // Update section number & offset for symbols that have them.
1003 if (Symbol->Section)
1004 Symbol->Data.SectionNumber = Symbol->Section->Number;
1005 Symbol->setIndex(Header.NumberOfSymbols++);
1006 // Update auxiliary symbol info.
1007 Symbol->Data.NumberOfAuxSymbols = Symbol->Aux.size();
1008 Header.NumberOfSymbols += Symbol->Data.NumberOfAuxSymbols;
1009 }
1010
1011 // Build string table.
1012 for (const auto &S : Sections)
1013 if (S->Name.size() > COFF::NameSize)
1014 Strings.add(S: S->Name);
1015 for (const auto &S : Symbols)
1016 if (S->Name.size() > COFF::NameSize)
1017 Strings.add(S: S->Name);
1018 Strings.finalize();
1019
1020 // Set names.
1021 for (const auto &S : Sections)
1022 SetSectionName(*S);
1023 for (auto &S : Symbols)
1024 SetSymbolName(*S);
1025
1026 // Fixup weak external references.
1027 for (auto &Symbol : Symbols) {
1028 if (Symbol->Other) {
1029 assert(Symbol->getIndex() != -1);
1030 assert(Symbol->Aux.size() == 1 && "Symbol must contain one aux symbol!");
1031 assert(Symbol->Aux[0].AuxType == ATWeakExternal &&
1032 "Symbol's aux symbol must be a Weak External!");
1033 Symbol->Aux[0].Aux.WeakExternal.TagIndex = Symbol->Other->getIndex();
1034 }
1035 }
1036
1037 // Fixup associative COMDAT sections.
1038 for (auto &Section : Sections) {
1039 if (Section->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
1040 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
1041 continue;
1042
1043 const MCSectionCOFF &MCSec = *Section->MCSection;
1044 const MCSymbol *AssocMCSym = MCSec.getCOMDATSymbol();
1045 assert(AssocMCSym);
1046
1047 // It's an error to try to associate with an undefined symbol or a symbol
1048 // without a section.
1049 if (!AssocMCSym->isInSection()) {
1050 getContext().reportError(
1051 L: SMLoc(), Msg: Twine("cannot make section ") + MCSec.getName() +
1052 Twine(" associative with sectionless symbol ") +
1053 AssocMCSym->getName());
1054 continue;
1055 }
1056
1057 const auto *AssocMCSec = cast<MCSectionCOFF>(Val: &AssocMCSym->getSection());
1058 assert(SectionMap.count(AssocMCSec));
1059 COFFSection *AssocSec = SectionMap[AssocMCSec];
1060
1061 // Skip this section if the associated section is unused.
1062 if (AssocSec->Number == -1)
1063 continue;
1064
1065 Section->Symbol->Aux[0].Aux.SectionDefinition.Number = AssocSec->Number;
1066 }
1067
1068 // Create the contents of the .llvm_addrsig section.
1069 if (Mode != DwoOnly && OWriter.getEmitAddrsigSection()) {
1070 auto *Sec = getContext().getCOFFSection(Section: ".llvm_addrsig",
1071 Characteristics: COFF::IMAGE_SCN_LNK_REMOVE);
1072 auto *Frag = cast<MCDataFragment>(Val: Sec->curFragList()->Head);
1073 raw_svector_ostream OS(Frag->getContentsForAppending());
1074 for (const MCSymbol *S : OWriter.AddrsigSyms) {
1075 if (!S->isRegistered())
1076 continue;
1077 if (!S->isTemporary()) {
1078 encodeULEB128(Value: S->getIndex(), OS);
1079 continue;
1080 }
1081
1082 MCSection *TargetSection = &S->getSection();
1083 assert(SectionMap.contains(TargetSection) &&
1084 "Section must already have been defined in "
1085 "executePostLayoutBinding!");
1086 encodeULEB128(Value: SectionMap[TargetSection]->Symbol->getIndex(), OS);
1087 }
1088 Frag->doneAppending();
1089 }
1090
1091 // Create the contents of the .llvm.call-graph-profile section.
1092 if (Mode != DwoOnly && !OWriter.getCGProfile().empty()) {
1093 auto *Sec = getContext().getCOFFSection(Section: ".llvm.call-graph-profile",
1094 Characteristics: COFF::IMAGE_SCN_LNK_REMOVE);
1095 auto *Frag = cast<MCDataFragment>(Val: Sec->curFragList()->Head);
1096 raw_svector_ostream OS(Frag->getContentsForAppending());
1097 for (const auto &CGPE : OWriter.getCGProfile()) {
1098 uint32_t FromIndex = CGPE.From->getSymbol().getIndex();
1099 uint32_t ToIndex = CGPE.To->getSymbol().getIndex();
1100 support::endian::write(os&: OS, value: FromIndex, endian: W.Endian);
1101 support::endian::write(os&: OS, value: ToIndex, endian: W.Endian);
1102 support::endian::write(os&: OS, value: CGPE.Count, endian: W.Endian);
1103 }
1104 Frag->doneAppending();
1105 }
1106
1107 assignFileOffsets();
1108
1109 // MS LINK expects to be able to use this timestamp to implement their
1110 // /INCREMENTAL feature.
1111 if (OWriter.IncrementalLinkerCompatible) {
1112 Header.TimeDateStamp = getTime();
1113 } else {
1114 // Have deterministic output if /INCREMENTAL isn't needed. Also matches GNU.
1115 Header.TimeDateStamp = 0;
1116 }
1117
1118 // Write it all to disk...
1119 WriteFileHeader(Header);
1120 writeSectionHeaders();
1121
1122#ifndef NDEBUG
1123 sections::iterator I = Sections.begin();
1124 sections::iterator IE = Sections.end();
1125 auto J = Asm->begin();
1126 auto JE = Asm->end();
1127 for (; I != IE && J != JE; ++I, ++J) {
1128 while (J != JE && ((Mode == NonDwoOnly && isDwoSection(*J)) ||
1129 (Mode == DwoOnly && !isDwoSection(*J))))
1130 ++J;
1131 assert(J != JE && (**I).MCSection == &*J && "Wrong bound MCSection");
1132 }
1133#endif
1134
1135 // Write section contents.
1136 for (std::unique_ptr<COFFSection> &Sec : Sections)
1137 writeSection(Sec: *Sec);
1138
1139 assert(W.OS.tell() == Header.PointerToSymbolTable &&
1140 "Header::PointerToSymbolTable is insane!");
1141
1142 // Write a symbol table.
1143 for (auto &Symbol : Symbols)
1144 if (Symbol->getIndex() != -1)
1145 WriteSymbol(S: *Symbol);
1146
1147 // Write a string table, which completes the entire COFF file.
1148 Strings.write(OS&: W.OS);
1149
1150 return W.OS.tell() - StartOffset;
1151}
1152
1153int WinCOFFWriter::getSectionNumber(const MCSection &Section) const {
1154 return SectionMap.at(Val: &Section)->Number;
1155}
1156
1157//------------------------------------------------------------------------------
1158// WinCOFFObjectWriter class implementation
1159
1160////////////////////////////////////////////////////////////////////////////////
1161// MCObjectWriter interface implementations
1162
1163void WinCOFFObjectWriter::reset() {
1164 IncrementalLinkerCompatible = false;
1165 ObjWriter->reset();
1166 if (DwoWriter)
1167 DwoWriter->reset();
1168 MCObjectWriter::reset();
1169}
1170
1171void WinCOFFObjectWriter::setAssembler(MCAssembler *Asm) {
1172 MCObjectWriter::setAssembler(Asm);
1173 ObjWriter->setAssembler(Asm);
1174 if (DwoWriter)
1175 DwoWriter->setAssembler(Asm);
1176}
1177
1178bool WinCOFFObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
1179 const MCSymbol &SymA, const MCFragment &FB, bool InSet,
1180 bool IsPCRel) const {
1181 // Don't drop relocations between functions, even if they are in the same text
1182 // section. Multiple Visual C++ linker features depend on having the
1183 // relocations present. The /INCREMENTAL flag will cause these relocations to
1184 // point to thunks, and the /GUARD:CF flag assumes that it can use relocations
1185 // to approximate the set of all address taken functions. LLD's implementation
1186 // of /GUARD:CF also relies on the existance of these relocations.
1187 uint16_t Type = cast<MCSymbolCOFF>(Val: SymA).getType();
1188 if ((Type >> COFF::SCT_COMPLEX_TYPE_SHIFT) == COFF::IMAGE_SYM_DTYPE_FUNCTION)
1189 return false;
1190 return &SymA.getSection() == FB.getParent();
1191}
1192
1193void WinCOFFObjectWriter::executePostLayoutBinding() {
1194 ObjWriter->executePostLayoutBinding();
1195 if (DwoWriter)
1196 DwoWriter->executePostLayoutBinding();
1197}
1198
1199void WinCOFFObjectWriter::recordRelocation(const MCFragment &F,
1200 const MCFixup &Fixup, MCValue Target,
1201 uint64_t &FixedValue) {
1202 assert(!isDwoSection(*F.getParent()) && "No relocation in Dwo sections");
1203 ObjWriter->recordRelocation(F, Fixup, Target, FixedValue);
1204}
1205
1206uint64_t WinCOFFObjectWriter::writeObject() {
1207 // If the assember had an error, then layout will not have completed, so we
1208 // cannot write an object file.
1209 if (getContext().hadError())
1210 return 0;
1211
1212 uint64_t TotalSize = ObjWriter->writeObject();
1213 if (DwoWriter)
1214 TotalSize += DwoWriter->writeObject();
1215 return TotalSize;
1216}
1217
1218int WinCOFFObjectWriter::getSectionNumber(const MCSection &Section) const {
1219 return ObjWriter->getSectionNumber(Section);
1220}
1221
1222MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_)
1223 : Machine(Machine_) {}
1224
1225// Pin the vtable to this file.
1226void MCWinCOFFObjectTargetWriter::anchor() {}
1227
1228//------------------------------------------------------------------------------
1229// WinCOFFObjectWriter factory function
1230
1231std::unique_ptr<MCObjectWriter> llvm::createWinCOFFObjectWriter(
1232 std::unique_ptr<MCWinCOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS) {
1233 return std::make_unique<WinCOFFObjectWriter>(args: std::move(MOTW), args&: OS);
1234}
1235
1236std::unique_ptr<MCObjectWriter> llvm::createWinCOFFDwoObjectWriter(
1237 std::unique_ptr<MCWinCOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS,
1238 raw_pwrite_stream &DwoOS) {
1239 return std::make_unique<WinCOFFObjectWriter>(args: std::move(MOTW), args&: OS, args&: DwoOS);
1240}
1241