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 &Sym);
172 COFFSection *createSection(StringRef Name);
173
174 void defineSection(MCSectionCOFF const &Sec);
175
176 COFFSymbol *getLinkedSymbol(const MCSymbol &Symbol);
177 void defineSymbol(const MCSymbolCOFF &Symbol);
178
179 void SetSymbolName(COFFSymbol &S);
180 void SetSectionName(COFFSection &S);
181
182 bool isUninitializedData(const 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 &Sym) {
248 COFFSymbol *&Ret = SymbolMap[&Sym];
249 if (!Ret)
250 Ret = createSymbol(Name: Sym.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(Sym: *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 MCSymbolCOFF &Symbol,
343 const MCAssembler &Asm) {
344 if (Symbol.isCommon() && Symbol.isExternal())
345 return Symbol.getCommonSize();
346
347 uint64_t Res;
348 if (!Asm.getSymbolOffset(S: Symbol, Val&: Res))
349 return 0;
350
351 return Res;
352}
353
354COFFSymbol *WinCOFFWriter::getLinkedSymbol(const MCSymbol &Symbol) {
355 if (!Symbol.isVariable())
356 return nullptr;
357
358 const auto *SymRef = dyn_cast<MCSymbolRefExpr>(Val: Symbol.getVariableValue());
359 if (!SymRef)
360 return nullptr;
361
362 auto &Aliasee = static_cast<const MCSymbolCOFF &>(SymRef->getSymbol());
363 if (Aliasee.isUndefined() || Aliasee.isExternal())
364 return getOrCreateCOFFSymbol(Sym: 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 MCSymbolCOFF &MCSym) {
372 const MCSymbol *Base = Asm->getBaseSymbol(Symbol: MCSym);
373 COFFSection *Sec = nullptr;
374 MCSectionCOFF *MCSec = nullptr;
375 if (Base && Base->getFragment()) {
376 MCSec = static_cast<MCSectionCOFF *>(Base->getFragment()->getParent());
377 Sec = SectionMap[MCSec];
378 }
379
380 if (Mode == NonDwoOnly && MCSec && isDwoSection(Sec: *MCSec))
381 return;
382
383 COFFSymbol *Sym = getOrCreateCOFFSymbol(Sym: MCSym);
384 COFFSymbol *Local = nullptr;
385 if (static_cast<const MCSymbolCOFF &>(MCSym)
386 .getWeakExternalCharacteristics()) {
387 Sym->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
388 Sym->Section = nullptr;
389
390 COFFSymbol *WeakDefault = getLinkedSymbol(Symbol: MCSym);
391 if (!WeakDefault) {
392 std::string WeakName = (".weak." + MCSym.getName() + ".default").str();
393 WeakDefault = createSymbol(Name: WeakName);
394 if (!Sec)
395 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
396 else
397 WeakDefault->Section = Sec;
398 WeakDefaults.insert(V: WeakDefault);
399 Local = WeakDefault;
400 }
401
402 Sym->Other = WeakDefault;
403
404 // Setup the Weak External auxiliary symbol.
405 Sym->Aux.resize(N: 1);
406 memset(s: &Sym->Aux[0], c: 0, n: sizeof(Sym->Aux[0]));
407 Sym->Aux[0].AuxType = ATWeakExternal;
408 Sym->Aux[0].Aux.WeakExternal.TagIndex = 0; // Filled in later
409 Sym->Aux[0].Aux.WeakExternal.Characteristics =
410 static_cast<const MCSymbolCOFF &>(MCSym)
411 .getWeakExternalCharacteristics();
412 } else {
413 if (!Base)
414 Sym->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
415 else
416 Sym->Section = Sec;
417 Local = Sym;
418 }
419
420 if (Local) {
421 Local->Data.Value = getSymbolValue(Symbol: MCSym, Asm: *Asm);
422
423 auto &SymbolCOFF = static_cast<const MCSymbolCOFF &>(MCSym);
424 Local->Data.Type = SymbolCOFF.getType();
425 Local->Data.StorageClass = SymbolCOFF.getClass();
426
427 // If no storage class was specified in the streamer, define it here.
428 if (Local->Data.StorageClass == COFF::IMAGE_SYM_CLASS_NULL) {
429 bool IsExternal =
430 MCSym.isExternal() || (!MCSym.getFragment() && !MCSym.isVariable());
431
432 Local->Data.StorageClass = IsExternal ? COFF::IMAGE_SYM_CLASS_EXTERNAL
433 : COFF::IMAGE_SYM_CLASS_STATIC;
434 }
435 }
436
437 Sym->MC = &MCSym;
438}
439
440void WinCOFFWriter::SetSectionName(COFFSection &S) {
441 if (S.Name.size() <= COFF::NameSize) {
442 std::memcpy(dest: S.Header.Name, src: S.Name.c_str(), n: S.Name.size());
443 return;
444 }
445
446 uint64_t StringTableEntry = Strings.getOffset(S: S.Name);
447 if (!COFF::encodeSectionName(Out: S.Header.Name, Offset: StringTableEntry))
448 report_fatal_error(reason: "COFF string table is greater than 64 GB.");
449}
450
451void WinCOFFWriter::SetSymbolName(COFFSymbol &S) {
452 if (S.Name.size() > COFF::NameSize)
453 S.set_name_offset(Strings.getOffset(S: S.Name));
454 else
455 std::memcpy(dest: S.Data.Name, src: S.Name.c_str(), n: S.Name.size());
456}
457
458bool WinCOFFWriter::isUninitializedData(const COFFSection &S) {
459 return (S.Header.Characteristics & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) !=
460 0;
461}
462
463//------------------------------------------------------------------------------
464// entity writing methods
465
466void WinCOFFWriter::WriteFileHeader(const COFF::header &Header) {
467 if (UseBigObj) {
468 W.write<uint16_t>(Val: COFF::IMAGE_FILE_MACHINE_UNKNOWN);
469 W.write<uint16_t>(Val: 0xFFFF);
470 W.write<uint16_t>(Val: COFF::BigObjHeader::MinBigObjectVersion);
471 W.write<uint16_t>(Val: Header.Machine);
472 W.write<uint32_t>(Val: Header.TimeDateStamp);
473 W.OS.write(Ptr: COFF::BigObjMagic, Size: sizeof(COFF::BigObjMagic));
474 W.write<uint32_t>(Val: 0);
475 W.write<uint32_t>(Val: 0);
476 W.write<uint32_t>(Val: 0);
477 W.write<uint32_t>(Val: 0);
478 W.write<uint32_t>(Val: Header.NumberOfSections);
479 W.write<uint32_t>(Val: Header.PointerToSymbolTable);
480 W.write<uint32_t>(Val: Header.NumberOfSymbols);
481 } else {
482 W.write<uint16_t>(Val: Header.Machine);
483 W.write<uint16_t>(Val: static_cast<int16_t>(Header.NumberOfSections));
484 W.write<uint32_t>(Val: Header.TimeDateStamp);
485 W.write<uint32_t>(Val: Header.PointerToSymbolTable);
486 W.write<uint32_t>(Val: Header.NumberOfSymbols);
487 W.write<uint16_t>(Val: Header.SizeOfOptionalHeader);
488 W.write<uint16_t>(Val: Header.Characteristics);
489 }
490}
491
492void WinCOFFWriter::WriteSymbol(const COFFSymbol &S) {
493 W.OS.write(Ptr: S.Data.Name, Size: COFF::NameSize);
494 W.write<uint32_t>(Val: S.Data.Value);
495 if (UseBigObj)
496 W.write<uint32_t>(Val: S.Data.SectionNumber);
497 else
498 W.write<uint16_t>(Val: static_cast<int16_t>(S.Data.SectionNumber));
499 W.write<uint16_t>(Val: S.Data.Type);
500 W.OS << char(S.Data.StorageClass);
501 W.OS << char(S.Data.NumberOfAuxSymbols);
502 WriteAuxiliarySymbols(S: S.Aux);
503}
504
505void WinCOFFWriter::WriteAuxiliarySymbols(
506 const COFFSymbol::AuxiliarySymbols &S) {
507 for (const AuxSymbol &i : S) {
508 switch (i.AuxType) {
509 case ATWeakExternal:
510 W.write<uint32_t>(Val: i.Aux.WeakExternal.TagIndex);
511 W.write<uint32_t>(Val: i.Aux.WeakExternal.Characteristics);
512 W.OS.write_zeros(NumZeros: sizeof(i.Aux.WeakExternal.unused));
513 if (UseBigObj)
514 W.OS.write_zeros(NumZeros: COFF::Symbol32Size - COFF::Symbol16Size);
515 break;
516 case ATFile:
517 W.OS.write(Ptr: reinterpret_cast<const char *>(&i.Aux),
518 Size: UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size);
519 break;
520 case ATSectionDefinition:
521 W.write<uint32_t>(Val: i.Aux.SectionDefinition.Length);
522 W.write<uint16_t>(Val: i.Aux.SectionDefinition.NumberOfRelocations);
523 W.write<uint16_t>(Val: i.Aux.SectionDefinition.NumberOfLinenumbers);
524 W.write<uint32_t>(Val: i.Aux.SectionDefinition.CheckSum);
525 W.write<uint16_t>(Val: static_cast<int16_t>(i.Aux.SectionDefinition.Number));
526 W.OS << char(i.Aux.SectionDefinition.Selection);
527 W.OS.write_zeros(NumZeros: sizeof(i.Aux.SectionDefinition.unused));
528 W.write<uint16_t>(
529 Val: static_cast<int16_t>(i.Aux.SectionDefinition.Number >> 16));
530 if (UseBigObj)
531 W.OS.write_zeros(NumZeros: COFF::Symbol32Size - COFF::Symbol16Size);
532 break;
533 }
534 }
535}
536
537// Write the section header.
538void WinCOFFWriter::writeSectionHeaders() {
539 // Section numbers must be monotonically increasing in the section
540 // header, but our Sections array is not sorted by section number,
541 // so make a copy of Sections and sort it.
542 std::vector<COFFSection *> Arr;
543 for (auto &Section : Sections)
544 Arr.push_back(x: Section.get());
545 llvm::sort(C&: Arr, Comp: [](const COFFSection *A, const COFFSection *B) {
546 return A->Number < B->Number;
547 });
548
549 for (auto &Section : Arr) {
550 if (Section->Number == -1)
551 continue;
552
553 COFF::section &S = Section->Header;
554 if (Section->Relocations.size() >= 0xffff)
555 S.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
556 W.OS.write(Ptr: S.Name, Size: COFF::NameSize);
557 W.write<uint32_t>(Val: S.VirtualSize);
558 W.write<uint32_t>(Val: S.VirtualAddress);
559 W.write<uint32_t>(Val: S.SizeOfRawData);
560 W.write<uint32_t>(Val: S.PointerToRawData);
561 W.write<uint32_t>(Val: S.PointerToRelocations);
562 W.write<uint32_t>(Val: S.PointerToLineNumbers);
563 W.write<uint16_t>(Val: S.NumberOfRelocations);
564 W.write<uint16_t>(Val: S.NumberOfLineNumbers);
565 W.write<uint32_t>(Val: S.Characteristics);
566 }
567}
568
569void WinCOFFWriter::WriteRelocation(const COFF::relocation &R) {
570 W.write<uint32_t>(Val: R.VirtualAddress);
571 W.write<uint32_t>(Val: R.SymbolTableIndex);
572 W.write<uint16_t>(Val: R.Type);
573}
574
575// Write MCSec's contents. What this function does is essentially
576// "Asm.writeSectionData(&MCSec)", but it's a bit complicated
577// because it needs to compute a CRC.
578uint32_t WinCOFFWriter::writeSectionContents(const MCSection &MCSec) {
579 // Save the contents of the section to a temporary buffer, we need this
580 // to CRC the data before we dump it into the object file.
581 SmallVector<char, 128> Buf;
582 raw_svector_ostream VecOS(Buf);
583 Asm->writeSectionData(OS&: VecOS, Section: &MCSec);
584
585 // Write the section contents to the object file.
586 W.OS << Buf;
587
588 // Calculate our CRC with an initial value of '0', this is not how
589 // JamCRC is specified but it aligns with the expected output.
590 JamCRC JC(/*Init=*/0);
591 JC.update(Data: ArrayRef(reinterpret_cast<uint8_t *>(Buf.data()), Buf.size()));
592 return JC.getCRC();
593}
594
595void WinCOFFWriter::writeSection(const COFFSection &Sec) {
596 if (Sec.Number == -1)
597 return;
598
599 // Write the section contents.
600 if (Sec.Header.PointerToRawData != 0) {
601 assert(W.OS.tell() == Sec.Header.PointerToRawData &&
602 "Section::PointerToRawData is insane!");
603
604 uint32_t CRC = writeSectionContents(MCSec: *Sec.MCSection);
605
606 // Update the section definition auxiliary symbol to record the CRC.
607 COFFSymbol::AuxiliarySymbols &AuxSyms = Sec.Symbol->Aux;
608 assert(AuxSyms.size() == 1 && AuxSyms[0].AuxType == ATSectionDefinition);
609 AuxSymbol &SecDef = AuxSyms[0];
610 SecDef.Aux.SectionDefinition.CheckSum = CRC;
611 } else if (isUninitializedData(S: Sec)) {
612 // Error if fixups or non-zero bytes are present.
613 writeSectionContents(MCSec: *Sec.MCSection);
614 }
615
616 // Write relocations for this section.
617 if (Sec.Relocations.empty()) {
618 assert(Sec.Header.PointerToRelocations == 0 &&
619 "Section::PointerToRelocations is insane!");
620 return;
621 }
622
623 assert(W.OS.tell() == Sec.Header.PointerToRelocations &&
624 "Section::PointerToRelocations is insane!");
625
626 if (Sec.Relocations.size() >= 0xffff) {
627 // In case of overflow, write actual relocation count as first
628 // relocation. Including the synthetic reloc itself (+ 1).
629 COFF::relocation R;
630 R.VirtualAddress = Sec.Relocations.size() + 1;
631 R.SymbolTableIndex = 0;
632 R.Type = 0;
633 WriteRelocation(R);
634 }
635
636 for (const auto &Relocation : Sec.Relocations)
637 WriteRelocation(R: Relocation.Data);
638}
639
640// Create .file symbols.
641void WinCOFFWriter::createFileSymbols() {
642 for (const std::pair<std::string, size_t> &It : OWriter.getFileNames()) {
643 // round up to calculate the number of auxiliary symbols required
644 const std::string &Name = It.first;
645 unsigned SymbolSize = UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size;
646 unsigned Count = (Name.size() + SymbolSize - 1) / SymbolSize;
647
648 COFFSymbol *File = createSymbol(Name: ".file");
649 File->Data.SectionNumber = COFF::IMAGE_SYM_DEBUG;
650 File->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE;
651 File->Aux.resize(N: Count);
652
653 unsigned Offset = 0;
654 unsigned Length = Name.size();
655 for (auto &Aux : File->Aux) {
656 Aux.AuxType = ATFile;
657
658 if (Length > SymbolSize) {
659 memcpy(dest: &Aux.Aux, src: Name.c_str() + Offset, n: SymbolSize);
660 Length = Length - SymbolSize;
661 } else {
662 memcpy(dest: &Aux.Aux, src: Name.c_str() + Offset, n: Length);
663 memset(s: (char *)&Aux.Aux + Length, c: 0, n: SymbolSize - Length);
664 break;
665 }
666
667 Offset += SymbolSize;
668 }
669 }
670}
671
672void WinCOFFWriter::setWeakDefaultNames() {
673 if (WeakDefaults.empty())
674 return;
675
676 // If multiple object files use a weak symbol (either with a regular
677 // defined default, or an absolute zero symbol as default), the defaults
678 // cause duplicate definitions unless their names are made unique. Look
679 // for a defined extern symbol, that isn't comdat - that should be unique
680 // unless there are other duplicate definitions. And if none is found,
681 // allow picking a comdat symbol, as that's still better than nothing.
682
683 COFFSymbol *Unique = nullptr;
684 for (bool AllowComdat : {false, true}) {
685 for (auto &Sym : Symbols) {
686 // Don't include the names of the defaults themselves
687 if (WeakDefaults.count(V: Sym.get()))
688 continue;
689 // Only consider external symbols
690 if (Sym->Data.StorageClass != COFF::IMAGE_SYM_CLASS_EXTERNAL)
691 continue;
692 // Only consider symbols defined in a section or that are absolute
693 if (!Sym->Section && Sym->Data.SectionNumber != COFF::IMAGE_SYM_ABSOLUTE)
694 continue;
695 if (!AllowComdat && Sym->Section &&
696 Sym->Section->Header.Characteristics & COFF::IMAGE_SCN_LNK_COMDAT)
697 continue;
698 Unique = Sym.get();
699 break;
700 }
701 if (Unique)
702 break;
703 }
704 // If we didn't find any unique symbol to use for the names, just skip this.
705 if (!Unique)
706 return;
707 for (auto *Sym : WeakDefaults) {
708 Sym->Name.append(RHS: ".");
709 Sym->Name.append(RHS: Unique->Name);
710 }
711}
712
713static bool isAssociative(const COFFSection &Section) {
714 return Section.Symbol->Aux[0].Aux.SectionDefinition.Selection ==
715 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
716}
717
718void WinCOFFWriter::assignSectionNumbers() {
719 size_t I = 1;
720 auto Assign = [&](COFFSection &Section) {
721 Section.Number = I;
722 Section.Symbol->Data.SectionNumber = I;
723 Section.Symbol->Aux[0].Aux.SectionDefinition.Number = I;
724 ++I;
725 };
726
727 // Although it is not explicitly requested by the Microsoft COFF spec,
728 // we should avoid emitting forward associative section references,
729 // because MSVC link.exe as of 2017 cannot handle that.
730 for (const std::unique_ptr<COFFSection> &Section : Sections)
731 if (!isAssociative(Section: *Section))
732 Assign(*Section);
733 for (const std::unique_ptr<COFFSection> &Section : Sections)
734 if (isAssociative(Section: *Section))
735 Assign(*Section);
736}
737
738// Assign file offsets to COFF object file structures.
739void WinCOFFWriter::assignFileOffsets() {
740 unsigned Offset = W.OS.tell();
741
742 Offset += UseBigObj ? COFF::Header32Size : COFF::Header16Size;
743 Offset += COFF::SectionSize * Header.NumberOfSections;
744
745 for (const auto &Section : *Asm) {
746 COFFSection *Sec = SectionMap[&Section];
747
748 if (!Sec || Sec->Number == -1)
749 continue;
750
751 Sec->Header.SizeOfRawData = Asm->getSectionAddressSize(Sec: Section);
752
753 if (!isUninitializedData(S: *Sec)) {
754 Sec->Header.PointerToRawData = Offset;
755 Offset += Sec->Header.SizeOfRawData;
756 }
757
758 if (!Sec->Relocations.empty()) {
759 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
760
761 if (RelocationsOverflow) {
762 // Signal overflow by setting NumberOfRelocations to max value. Actual
763 // size is found in reloc #0. Microsoft tools understand this.
764 Sec->Header.NumberOfRelocations = 0xffff;
765 } else {
766 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
767 }
768 Sec->Header.PointerToRelocations = Offset;
769
770 if (RelocationsOverflow) {
771 // Reloc #0 will contain actual count, so make room for it.
772 Offset += COFF::RelocationSize;
773 }
774
775 Offset += COFF::RelocationSize * Sec->Relocations.size();
776
777 for (auto &Relocation : Sec->Relocations) {
778 assert(Relocation.Symb->getIndex() != -1);
779 if (Header.Machine != COFF::IMAGE_FILE_MACHINE_R4000 ||
780 Relocation.Data.Type != COFF::IMAGE_REL_MIPS_PAIR) {
781 Relocation.Data.SymbolTableIndex = Relocation.Symb->getIndex();
782 }
783 }
784 }
785
786 assert(Sec->Symbol->Aux.size() == 1 &&
787 "Section's symbol must have one aux!");
788 AuxSymbol &Aux = Sec->Symbol->Aux[0];
789 assert(Aux.AuxType == ATSectionDefinition &&
790 "Section's symbol's aux symbol must be a Section Definition!");
791 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
792 Aux.Aux.SectionDefinition.NumberOfRelocations =
793 Sec->Header.NumberOfRelocations;
794 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
795 Sec->Header.NumberOfLineNumbers;
796 }
797
798 Header.PointerToSymbolTable = Offset;
799}
800
801void WinCOFFWriter::reset() {
802 memset(s: &Header, c: 0, n: sizeof(Header));
803 Header.Machine = OWriter.TargetObjectWriter->getMachine();
804 Sections.clear();
805 Symbols.clear();
806 Strings.clear();
807 SectionMap.clear();
808 SymbolMap.clear();
809 WeakDefaults.clear();
810}
811
812void WinCOFFWriter::executePostLayoutBinding() {
813 // "Define" each section & symbol. This creates section & symbol
814 // entries in the staging area.
815 for (const auto &Section : *Asm) {
816 if ((Mode == NonDwoOnly && isDwoSection(Sec: Section)) ||
817 (Mode == DwoOnly && !isDwoSection(Sec: Section)))
818 continue;
819 defineSection(MCSec: static_cast<const MCSectionCOFF &>(Section));
820 }
821
822 if (Mode != DwoOnly) {
823 for (const MCSymbol &Symbol : Asm->symbols()) {
824 auto &Sym = static_cast<const MCSymbolCOFF &>(Symbol);
825 // Define non-temporary or temporary static (private-linkage) symbols
826 if (!Sym.isTemporary() || Sym.getClass() == COFF::IMAGE_SYM_CLASS_STATIC)
827 defineSymbol(MCSym: Sym);
828 }
829 }
830
831 UseBigObj = Sections.size() > COFF::MaxNumberOfSections16;
832 Header.NumberOfSections = Sections.size();
833 Header.NumberOfSymbols = 0;
834 if (Sections.size() > INT32_MAX)
835 report_fatal_error(
836 reason: "PE COFF object files can't have more than 2147483647 sections");
837
838 assignSectionNumbers();
839}
840
841void WinCOFFWriter::recordRelocation(const MCFragment &F, const MCFixup &Fixup,
842 MCValue Target, uint64_t &FixedValue) {
843 assert(Target.getAddSym() && "Relocation must reference a symbol!");
844
845 const MCSymbol &A = *Target.getAddSym();
846 if (!A.isRegistered()) {
847 getContext().reportError(L: Fixup.getLoc(), Msg: Twine("symbol '") + A.getName() +
848 "' can not be undefined");
849 return;
850 }
851 if (A.isTemporary() && A.isUndefined()) {
852 getContext().reportError(L: Fixup.getLoc(), Msg: Twine("assembler label '") +
853 A.getName() +
854 "' can not be undefined");
855 return;
856 }
857
858 MCSection *MCSec = F.getParent();
859
860 // Mark this symbol as requiring an entry in the symbol table.
861 assert(SectionMap.contains(MCSec) &&
862 "Section must already have been defined in executePostLayoutBinding!");
863
864 COFFSection *Sec = SectionMap[MCSec];
865 if (const MCSymbol *B = Target.getSubSym()) {
866 if (!B->getFragment()) {
867 getContext().reportError(
868 L: Fixup.getLoc(),
869 Msg: Twine("symbol '") + B->getName() +
870 "' can not be undefined in a subtraction expression");
871 return;
872 }
873
874 // Offset of the symbol in the section
875 int64_t OffsetOfB = Asm->getSymbolOffset(S: *B);
876
877 // Offset of the relocation in the section
878 int64_t OffsetOfRelocation = Asm->getFragmentOffset(F) + Fixup.getOffset();
879
880 FixedValue = (OffsetOfRelocation - OffsetOfB) + Target.getConstant();
881 } else {
882 FixedValue = Target.getConstant();
883 }
884
885 COFFRelocation Reloc;
886
887 Reloc.Data.SymbolTableIndex = 0;
888 Reloc.Data.VirtualAddress = Asm->getFragmentOffset(F);
889
890 // Turn relocations for temporary symbols into section relocations.
891 if (A.isTemporary() && !SymbolMap[&A]) {
892 MCSection *TargetSection = &A.getSection();
893 assert(
894 SectionMap.contains(TargetSection) &&
895 "Section must already have been defined in executePostLayoutBinding!");
896 COFFSection *Section = SectionMap[TargetSection];
897 Reloc.Symb = Section->Symbol;
898 FixedValue += Asm->getSymbolOffset(S: A);
899 // Technically, we should do the final adjustments of FixedValue (below)
900 // before picking an offset symbol, otherwise we might choose one which
901 // is slightly too far away. The relocations where it really matters
902 // (arm64 adrp relocations) don't get any offset though.
903 if (UseOffsetLabels && !Section->OffsetSymbols.empty()) {
904 uint64_t LabelIndex = FixedValue >> OffsetLabelIntervalBits;
905 if (LabelIndex > 0) {
906 if (LabelIndex <= Section->OffsetSymbols.size())
907 Reloc.Symb = Section->OffsetSymbols[LabelIndex - 1];
908 else
909 Reloc.Symb = Section->OffsetSymbols.back();
910 FixedValue -= Reloc.Symb->Data.Value;
911 }
912 }
913 } else {
914 assert(
915 SymbolMap.contains(&A) &&
916 "Symbol must already have been defined in executePostLayoutBinding!");
917 Reloc.Symb = SymbolMap[&A];
918 }
919
920 ++Reloc.Symb->Relocations;
921
922 Reloc.Data.VirtualAddress += Fixup.getOffset();
923 Reloc.Data.Type = OWriter.TargetObjectWriter->getRelocType(
924 Ctx&: getContext(), Target, Fixup, IsCrossSection: Target.getSubSym(), MAB: Asm->getBackend());
925
926 // The *_REL32 relocations are relative to the end of the relocation,
927 // not to the start.
928 if ((Header.Machine == COFF::IMAGE_FILE_MACHINE_AMD64 &&
929 Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32) ||
930 (Header.Machine == COFF::IMAGE_FILE_MACHINE_I386 &&
931 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32) ||
932 (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT &&
933 Reloc.Data.Type == COFF::IMAGE_REL_ARM_REL32) ||
934 (COFF::isAnyArm64(Machine: Header.Machine) &&
935 Reloc.Data.Type == COFF::IMAGE_REL_ARM64_REL32))
936 FixedValue += 4;
937
938 if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) {
939 switch (Reloc.Data.Type) {
940 case COFF::IMAGE_REL_ARM_ABSOLUTE:
941 case COFF::IMAGE_REL_ARM_ADDR32:
942 case COFF::IMAGE_REL_ARM_ADDR32NB:
943 case COFF::IMAGE_REL_ARM_TOKEN:
944 case COFF::IMAGE_REL_ARM_SECTION:
945 case COFF::IMAGE_REL_ARM_SECREL:
946 break;
947 case COFF::IMAGE_REL_ARM_BRANCH11:
948 case COFF::IMAGE_REL_ARM_BLX11:
949 // IMAGE_REL_ARM_BRANCH11 and IMAGE_REL_ARM_BLX11 are only used for
950 // pre-ARMv7, which implicitly rules it out of ARMNT (it would be valid
951 // for Windows CE).
952 case COFF::IMAGE_REL_ARM_BRANCH24:
953 case COFF::IMAGE_REL_ARM_BLX24:
954 case COFF::IMAGE_REL_ARM_MOV32A:
955 // IMAGE_REL_ARM_BRANCH24, IMAGE_REL_ARM_BLX24, IMAGE_REL_ARM_MOV32A are
956 // only used for ARM mode code, which is documented as being unsupported
957 // by Windows on ARM. Empirical proof indicates that masm is able to
958 // generate the relocations however the rest of the MSVC toolchain is
959 // unable to handle it.
960 llvm_unreachable("unsupported relocation");
961 break;
962 case COFF::IMAGE_REL_ARM_MOV32T:
963 break;
964 case COFF::IMAGE_REL_ARM_BRANCH20T:
965 case COFF::IMAGE_REL_ARM_BRANCH24T:
966 case COFF::IMAGE_REL_ARM_BLX23T:
967 // IMAGE_REL_BRANCH20T, IMAGE_REL_ARM_BRANCH24T, IMAGE_REL_ARM_BLX23T all
968 // perform a 4 byte adjustment to the relocation. Relative branches are
969 // offset by 4 on ARM, however, because there is no RELA relocations, all
970 // branches are offset by 4.
971 FixedValue = FixedValue + 4;
972 break;
973 }
974 }
975
976 // The fixed value never makes sense for section indices, ignore it.
977 if (Fixup.getKind() == FK_SecRel_2)
978 FixedValue = 0;
979
980 if (OWriter.TargetObjectWriter->recordRelocation(Fixup)) {
981 Sec->Relocations.push_back(x: Reloc);
982 if (Header.Machine == COFF::IMAGE_FILE_MACHINE_R4000 &&
983 (Reloc.Data.Type == COFF::IMAGE_REL_MIPS_REFHI ||
984 Reloc.Data.Type == COFF::IMAGE_REL_MIPS_SECRELHI)) {
985 // IMAGE_REL_MIPS_REFHI and IMAGE_REL_MIPS_SECRELHI *must*
986 // be followed by IMAGE_REL_MIPS_PAIR
987 auto RelocPair = Reloc;
988 RelocPair.Data.Type = COFF::IMAGE_REL_MIPS_PAIR;
989 Sec->Relocations.push_back(x: RelocPair);
990 }
991 }
992}
993
994static std::time_t getTime() {
995 std::time_t Now = time(timer: nullptr);
996 if (Now < 0 || !isUInt<32>(x: Now))
997 return UINT32_MAX;
998 return Now;
999}
1000
1001uint64_t WinCOFFWriter::writeObject() {
1002 uint64_t StartOffset = W.OS.tell();
1003
1004 setWeakDefaultNames();
1005 if (Mode != DwoOnly)
1006 createFileSymbols();
1007
1008 for (auto &Symbol : Symbols) {
1009 // Update section number & offset for symbols that have them.
1010 if (Symbol->Section)
1011 Symbol->Data.SectionNumber = Symbol->Section->Number;
1012 Symbol->setIndex(Header.NumberOfSymbols++);
1013 // Update auxiliary symbol info.
1014 Symbol->Data.NumberOfAuxSymbols = Symbol->Aux.size();
1015 Header.NumberOfSymbols += Symbol->Data.NumberOfAuxSymbols;
1016 }
1017
1018 // Build string table.
1019 for (const auto &S : Sections)
1020 if (S->Name.size() > COFF::NameSize)
1021 Strings.add(S: S->Name);
1022 for (const auto &S : Symbols)
1023 if (S->Name.size() > COFF::NameSize)
1024 Strings.add(S: S->Name);
1025 Strings.finalize();
1026
1027 // Set names.
1028 for (const auto &S : Sections)
1029 SetSectionName(*S);
1030 for (auto &S : Symbols)
1031 SetSymbolName(*S);
1032
1033 // Fixup weak external references.
1034 for (auto &Symbol : Symbols) {
1035 if (Symbol->Other) {
1036 assert(Symbol->getIndex() != -1);
1037 assert(Symbol->Aux.size() == 1 && "Symbol must contain one aux symbol!");
1038 assert(Symbol->Aux[0].AuxType == ATWeakExternal &&
1039 "Symbol's aux symbol must be a Weak External!");
1040 Symbol->Aux[0].Aux.WeakExternal.TagIndex = Symbol->Other->getIndex();
1041 }
1042 }
1043
1044 // Fixup associative COMDAT sections.
1045 for (auto &Section : Sections) {
1046 if (Section->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
1047 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
1048 continue;
1049
1050 const MCSectionCOFF &MCSec = *Section->MCSection;
1051 const MCSymbol *AssocMCSym = MCSec.getCOMDATSymbol();
1052 assert(AssocMCSym);
1053
1054 // It's an error to try to associate with an undefined symbol or a symbol
1055 // without a section.
1056 if (!AssocMCSym->isInSection()) {
1057 getContext().reportError(
1058 L: SMLoc(), Msg: Twine("cannot make section ") + MCSec.getName() +
1059 Twine(" associative with sectionless symbol ") +
1060 AssocMCSym->getName());
1061 continue;
1062 }
1063
1064 const auto *AssocMCSec =
1065 static_cast<const MCSectionCOFF *>(&AssocMCSym->getSection());
1066 assert(SectionMap.count(AssocMCSec));
1067 COFFSection *AssocSec = SectionMap[AssocMCSec];
1068
1069 // Skip this section if the associated section is unused.
1070 if (AssocSec->Number == -1)
1071 continue;
1072
1073 Section->Symbol->Aux[0].Aux.SectionDefinition.Number = AssocSec->Number;
1074 }
1075
1076 // Create the contents of the .llvm_addrsig section.
1077 if (Mode != DwoOnly && OWriter.getEmitAddrsigSection()) {
1078 SmallString<0> Content;
1079 raw_svector_ostream OS(Content);
1080 for (const MCSymbol *S : OWriter.AddrsigSyms) {
1081 if (!S->isRegistered())
1082 continue;
1083 if (!S->isTemporary()) {
1084 encodeULEB128(Value: S->getIndex(), OS);
1085 continue;
1086 }
1087
1088 MCSection *TargetSection = &S->getSection();
1089 assert(SectionMap.contains(TargetSection) &&
1090 "Section must already have been defined in "
1091 "executePostLayoutBinding!");
1092 encodeULEB128(Value: SectionMap[TargetSection]->Symbol->getIndex(), OS);
1093 }
1094 auto *Sec = getContext().getCOFFSection(Section: ".llvm_addrsig",
1095 Characteristics: COFF::IMAGE_SCN_LNK_REMOVE);
1096 Sec->curFragList()->Tail->setVarContents(OS.str());
1097 }
1098
1099 // Create the contents of the .llvm.call-graph-profile section.
1100 if (Mode != DwoOnly && !OWriter.getCGProfile().empty()) {
1101 SmallString<0> Content;
1102 raw_svector_ostream OS(Content);
1103 for (const auto &CGPE : OWriter.getCGProfile()) {
1104 uint32_t FromIndex = CGPE.From->getSymbol().getIndex();
1105 uint32_t ToIndex = CGPE.To->getSymbol().getIndex();
1106 support::endian::write(os&: OS, value: FromIndex, endian: W.Endian);
1107 support::endian::write(os&: OS, value: ToIndex, endian: W.Endian);
1108 support::endian::write(os&: OS, value: CGPE.Count, endian: W.Endian);
1109 }
1110 auto *Sec = getContext().getCOFFSection(Section: ".llvm.call-graph-profile",
1111 Characteristics: COFF::IMAGE_SCN_LNK_REMOVE);
1112 Sec->curFragList()->Tail->setVarContents(OS.str());
1113 }
1114
1115 assignFileOffsets();
1116
1117 // MS LINK expects to be able to use this timestamp to implement their
1118 // /INCREMENTAL feature.
1119 if (OWriter.IncrementalLinkerCompatible) {
1120 Header.TimeDateStamp = getTime();
1121 } else {
1122 // Have deterministic output if /INCREMENTAL isn't needed. Also matches GNU.
1123 Header.TimeDateStamp = 0;
1124 }
1125
1126 // Write it all to disk...
1127 WriteFileHeader(Header);
1128 writeSectionHeaders();
1129
1130#ifndef NDEBUG
1131 sections::iterator I = Sections.begin();
1132 sections::iterator IE = Sections.end();
1133 auto J = Asm->begin();
1134 auto JE = Asm->end();
1135 for (; I != IE && J != JE; ++I, ++J) {
1136 while (J != JE && ((Mode == NonDwoOnly && isDwoSection(*J)) ||
1137 (Mode == DwoOnly && !isDwoSection(*J))))
1138 ++J;
1139 assert(J != JE && (**I).MCSection == &*J && "Wrong bound MCSection");
1140 }
1141#endif
1142
1143 // Write section contents.
1144 for (std::unique_ptr<COFFSection> &Sec : Sections)
1145 writeSection(Sec: *Sec);
1146
1147 assert(W.OS.tell() == Header.PointerToSymbolTable &&
1148 "Header::PointerToSymbolTable is insane!");
1149
1150 // Write a symbol table.
1151 for (auto &Symbol : Symbols)
1152 if (Symbol->getIndex() != -1)
1153 WriteSymbol(S: *Symbol);
1154
1155 // Write a string table, which completes the entire COFF file.
1156 Strings.write(OS&: W.OS);
1157
1158 return W.OS.tell() - StartOffset;
1159}
1160
1161int WinCOFFWriter::getSectionNumber(const MCSection &Section) const {
1162 return SectionMap.at(Val: &Section)->Number;
1163}
1164
1165//------------------------------------------------------------------------------
1166// WinCOFFObjectWriter class implementation
1167
1168////////////////////////////////////////////////////////////////////////////////
1169// MCObjectWriter interface implementations
1170
1171void WinCOFFObjectWriter::reset() {
1172 IncrementalLinkerCompatible = false;
1173 ObjWriter->reset();
1174 if (DwoWriter)
1175 DwoWriter->reset();
1176 MCObjectWriter::reset();
1177}
1178
1179void WinCOFFObjectWriter::setAssembler(MCAssembler *Asm) {
1180 MCObjectWriter::setAssembler(Asm);
1181 ObjWriter->setAssembler(Asm);
1182 if (DwoWriter)
1183 DwoWriter->setAssembler(Asm);
1184}
1185
1186bool WinCOFFObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
1187 const MCSymbol &SymA, const MCFragment &FB, bool InSet,
1188 bool IsPCRel) const {
1189 // Don't drop relocations between functions, even if they are in the same text
1190 // section. Multiple Visual C++ linker features depend on having the
1191 // relocations present. The /INCREMENTAL flag will cause these relocations to
1192 // point to thunks, and the /GUARD:CF flag assumes that it can use relocations
1193 // to approximate the set of all address taken functions. LLD's implementation
1194 // of /GUARD:CF also relies on the existance of these relocations.
1195 uint16_t Type = static_cast<const MCSymbolCOFF &>(SymA).getType();
1196 if ((Type >> COFF::SCT_COMPLEX_TYPE_SHIFT) == COFF::IMAGE_SYM_DTYPE_FUNCTION)
1197 return false;
1198 return &SymA.getSection() == FB.getParent();
1199}
1200
1201void WinCOFFObjectWriter::executePostLayoutBinding() {
1202 ObjWriter->executePostLayoutBinding();
1203 if (DwoWriter)
1204 DwoWriter->executePostLayoutBinding();
1205}
1206
1207void WinCOFFObjectWriter::recordRelocation(const MCFragment &F,
1208 const MCFixup &Fixup, MCValue Target,
1209 uint64_t &FixedValue) {
1210 assert(!isDwoSection(*F.getParent()) && "No relocation in Dwo sections");
1211 ObjWriter->recordRelocation(F, Fixup, Target, FixedValue);
1212}
1213
1214uint64_t WinCOFFObjectWriter::writeObject() {
1215 // If the assember had an error, then layout will not have completed, so we
1216 // cannot write an object file.
1217 if (getContext().hadError())
1218 return 0;
1219
1220 uint64_t TotalSize = ObjWriter->writeObject();
1221 if (DwoWriter)
1222 TotalSize += DwoWriter->writeObject();
1223 return TotalSize;
1224}
1225
1226int WinCOFFObjectWriter::getSectionNumber(const MCSection &Section) const {
1227 return ObjWriter->getSectionNumber(Section);
1228}
1229
1230MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_)
1231 : Machine(Machine_) {}
1232
1233// Pin the vtable to this file.
1234void MCWinCOFFObjectTargetWriter::anchor() {}
1235
1236//------------------------------------------------------------------------------
1237// WinCOFFObjectWriter factory function
1238
1239std::unique_ptr<MCObjectWriter> llvm::createWinCOFFObjectWriter(
1240 std::unique_ptr<MCWinCOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS) {
1241 return std::make_unique<WinCOFFObjectWriter>(args: std::move(MOTW), args&: OS);
1242}
1243
1244std::unique_ptr<MCObjectWriter> llvm::createWinCOFFDwoObjectWriter(
1245 std::unique_ptr<MCWinCOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS,
1246 raw_pwrite_stream &DwoOS) {
1247 return std::make_unique<WinCOFFObjectWriter>(args: std::move(MOTW), args&: OS, args&: DwoOS);
1248}
1249