1 //===-- llvm/MC/WinCOFFObjectWriter.cpp -------------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains an implementation of a Win32 COFF object file writer.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #define DEBUG_TYPE "WinCOFFObjectWriter"
15
16 #include "llvm/MC/MCObjectWriter.h"
17 #include "llvm/MC/MCSection.h"
18 #include "llvm/MC/MCContext.h"
19 #include "llvm/MC/MCSymbol.h"
20 #include "llvm/MC/MCExpr.h"
21 #include "llvm/MC/MCValue.h"
22 #include "llvm/MC/MCAssembler.h"
23 #include "llvm/MC/MCAsmLayout.h"
24 #include "llvm/MC/MCSectionCOFF.h"
25 #include "llvm/MC/MCWinCOFFObjectWriter.h"
26
27 #include "llvm/ADT/DenseMap.h"
28 #include "llvm/ADT/OwningPtr.h"
29 #include "llvm/ADT/StringMap.h"
30 #include "llvm/ADT/StringRef.h"
31
32 #include "llvm/Support/COFF.h"
33 #include "llvm/Support/Debug.h"
34 #include "llvm/Support/ErrorHandling.h"
35
36 #include "llvm/Support/TimeValue.h"
37
38 #include <cstdio>
39
40 using namespace llvm;
41
42 namespace {
43 typedef llvm::SmallString<COFF::NameSize> name;
44
45 enum AuxiliaryType {
46 ATFunctionDefinition,
47 ATbfAndefSymbol,
48 ATWeakExternal,
49 ATFile,
50 ATSectionDefinition
51 };
52
53 struct AuxSymbol {
54 AuxiliaryType AuxType;
55 COFF::Auxiliary Aux;
56 };
57
58 class COFFSymbol;
59 class COFFSection;
60
61 class COFFSymbol {
62 public:
63 COFF::symbol Data;
64
65 typedef llvm::SmallVector<AuxSymbol, 1> AuxiliarySymbols;
66
67 name Name;
68 int Index;
69 AuxiliarySymbols Aux;
70 COFFSymbol *Other;
71 COFFSection *Section;
72 int Relocations;
73
74 MCSymbolData const *MCData;
75
76 COFFSymbol(llvm::StringRef name);
77 size_t size() const;
78 void set_name_offset(uint32_t Offset);
79
80 bool should_keep() const;
81 };
82
83 // This class contains staging data for a COFF relocation entry.
84 struct COFFRelocation {
85 COFF::relocation Data;
86 COFFSymbol *Symb;
87
COFFRelocation__anon39a7a0d70111::COFFRelocation88 COFFRelocation() : Symb(NULL) {}
size__anon39a7a0d70111::COFFRelocation89 static size_t size() { return COFF::RelocationSize; }
90 };
91
92 typedef std::vector<COFFRelocation> relocations;
93
94 class COFFSection {
95 public:
96 COFF::section Header;
97
98 std::string Name;
99 int Number;
100 MCSectionData const *MCData;
101 COFFSymbol *Symbol;
102 relocations Relocations;
103
104 COFFSection(llvm::StringRef name);
105 static size_t size();
106 };
107
108 // This class holds the COFF string table.
109 class StringTable {
110 typedef llvm::StringMap<size_t> map;
111 map Map;
112
113 void update_length();
114 public:
115 std::vector<char> Data;
116
117 StringTable();
118 size_t size() const;
119 size_t insert(llvm::StringRef String);
120 };
121
122 class WinCOFFObjectWriter : public MCObjectWriter {
123 public:
124
125 typedef std::vector<COFFSymbol*> symbols;
126 typedef std::vector<COFFSection*> sections;
127
128 typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map;
129 typedef DenseMap<MCSection const *, COFFSection *> section_map;
130
131 llvm::OwningPtr<MCWinCOFFObjectTargetWriter> TargetObjectWriter;
132
133 // Root level file contents.
134 COFF::header Header;
135 sections Sections;
136 symbols Symbols;
137 StringTable Strings;
138
139 // Maps used during object file creation.
140 section_map SectionMap;
141 symbol_map SymbolMap;
142
143 WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, raw_ostream &OS);
144 ~WinCOFFObjectWriter();
145
146 COFFSymbol *createSymbol(StringRef Name);
147 COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol);
148 COFFSection *createSection(StringRef Name);
149
150 template <typename object_t, typename list_t>
151 object_t *createCOFFEntity(llvm::StringRef Name, list_t &List);
152
153 void DefineSection(MCSectionData const &SectionData);
154 void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler);
155
156 void MakeSymbolReal(COFFSymbol &S, size_t Index);
157 void MakeSectionReal(COFFSection &S, size_t Number);
158
159 bool ExportSection(COFFSection const *S);
160 bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm);
161
162 bool IsPhysicalSection(COFFSection *S);
163
164 // Entity writing methods.
165
166 void WriteFileHeader(const COFF::header &Header);
167 void WriteSymbol(const COFFSymbol *S);
168 void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
169 void WriteSectionHeader(const COFF::section &S);
170 void WriteRelocation(const COFF::relocation &R);
171
172 // MCObjectWriter interface implementation.
173
174 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout);
175
176 void RecordRelocation(const MCAssembler &Asm,
177 const MCAsmLayout &Layout,
178 const MCFragment *Fragment,
179 const MCFixup &Fixup,
180 MCValue Target,
181 uint64_t &FixedValue);
182
183 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
184 };
185 }
186
write_uint32_le(void * Data,uint32_t const & Value)187 static inline void write_uint32_le(void *Data, uint32_t const &Value) {
188 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
189 Ptr[0] = (Value & 0x000000FF) >> 0;
190 Ptr[1] = (Value & 0x0000FF00) >> 8;
191 Ptr[2] = (Value & 0x00FF0000) >> 16;
192 Ptr[3] = (Value & 0xFF000000) >> 24;
193 }
194
write_uint16_le(void * Data,uint16_t const & Value)195 static inline void write_uint16_le(void *Data, uint16_t const &Value) {
196 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
197 Ptr[0] = (Value & 0x00FF) >> 0;
198 Ptr[1] = (Value & 0xFF00) >> 8;
199 }
200
write_uint8_le(void * Data,uint8_t const & Value)201 static inline void write_uint8_le(void *Data, uint8_t const &Value) {
202 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
203 Ptr[0] = (Value & 0xFF) >> 0;
204 }
205
206 //------------------------------------------------------------------------------
207 // Symbol class implementation
208
COFFSymbol(llvm::StringRef name)209 COFFSymbol::COFFSymbol(llvm::StringRef name)
210 : Name(name.begin(), name.end())
211 , Other(NULL)
212 , Section(NULL)
213 , Relocations(0)
214 , MCData(NULL) {
215 memset(&Data, 0, sizeof(Data));
216 }
217
size() const218 size_t COFFSymbol::size() const {
219 return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
220 }
221
222 // In the case that the name does not fit within 8 bytes, the offset
223 // into the string table is stored in the last 4 bytes instead, leaving
224 // the first 4 bytes as 0.
set_name_offset(uint32_t Offset)225 void COFFSymbol::set_name_offset(uint32_t Offset) {
226 write_uint32_le(Data.Name + 0, 0);
227 write_uint32_le(Data.Name + 4, Offset);
228 }
229
230 /// logic to decide if the symbol should be reported in the symbol table
should_keep() const231 bool COFFSymbol::should_keep() const {
232 // no section means its external, keep it
233 if (Section == NULL)
234 return true;
235
236 // if it has relocations pointing at it, keep it
237 if (Relocations > 0) {
238 assert(Section->Number != -1 && "Sections with relocations must be real!");
239 return true;
240 }
241
242 // if the section its in is being droped, drop it
243 if (Section->Number == -1)
244 return false;
245
246 // if it is the section symbol, keep it
247 if (Section->Symbol == this)
248 return true;
249
250 // if its temporary, drop it
251 if (MCData && MCData->getSymbol().isTemporary())
252 return false;
253
254 // otherwise, keep it
255 return true;
256 }
257
258 //------------------------------------------------------------------------------
259 // Section class implementation
260
COFFSection(llvm::StringRef name)261 COFFSection::COFFSection(llvm::StringRef name)
262 : Name(name)
263 , MCData(NULL)
264 , Symbol(NULL) {
265 memset(&Header, 0, sizeof(Header));
266 }
267
size()268 size_t COFFSection::size() {
269 return COFF::SectionSize;
270 }
271
272 //------------------------------------------------------------------------------
273 // StringTable class implementation
274
275 /// Write the length of the string table into Data.
276 /// The length of the string table includes uint32 length header.
update_length()277 void StringTable::update_length() {
278 write_uint32_le(&Data.front(), Data.size());
279 }
280
StringTable()281 StringTable::StringTable() {
282 // The string table data begins with the length of the entire string table
283 // including the length header. Allocate space for this header.
284 Data.resize(4);
285 update_length();
286 }
287
size() const288 size_t StringTable::size() const {
289 return Data.size();
290 }
291
292 /// Add String to the table iff it is not already there.
293 /// @returns the index into the string table where the string is now located.
insert(llvm::StringRef String)294 size_t StringTable::insert(llvm::StringRef String) {
295 map::iterator i = Map.find(String);
296
297 if (i != Map.end())
298 return i->second;
299
300 size_t Offset = Data.size();
301
302 // Insert string data into string table.
303 Data.insert(Data.end(), String.begin(), String.end());
304 Data.push_back('\0');
305
306 // Put a reference to it in the map.
307 Map[String] = Offset;
308
309 // Update the internal length field.
310 update_length();
311
312 return Offset;
313 }
314
315 //------------------------------------------------------------------------------
316 // WinCOFFObjectWriter class implementation
317
WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter * MOTW,raw_ostream & OS)318 WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
319 raw_ostream &OS)
320 : MCObjectWriter(OS, true)
321 , TargetObjectWriter(MOTW) {
322 memset(&Header, 0, sizeof(Header));
323
324 Header.Machine = TargetObjectWriter->getMachine();
325 }
326
~WinCOFFObjectWriter()327 WinCOFFObjectWriter::~WinCOFFObjectWriter() {
328 for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I)
329 delete *I;
330 for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I)
331 delete *I;
332 }
333
createSymbol(StringRef Name)334 COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
335 return createCOFFEntity<COFFSymbol>(Name, Symbols);
336 }
337
GetOrCreateCOFFSymbol(const MCSymbol * Symbol)338 COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
339 symbol_map::iterator i = SymbolMap.find(Symbol);
340 if (i != SymbolMap.end())
341 return i->second;
342 COFFSymbol *RetSymbol
343 = createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
344 SymbolMap[Symbol] = RetSymbol;
345 return RetSymbol;
346 }
347
createSection(llvm::StringRef Name)348 COFFSection *WinCOFFObjectWriter::createSection(llvm::StringRef Name) {
349 return createCOFFEntity<COFFSection>(Name, Sections);
350 }
351
352 /// A template used to lookup or create a symbol/section, and initialize it if
353 /// needed.
354 template <typename object_t, typename list_t>
createCOFFEntity(llvm::StringRef Name,list_t & List)355 object_t *WinCOFFObjectWriter::createCOFFEntity(llvm::StringRef Name,
356 list_t &List) {
357 object_t *Object = new object_t(Name);
358
359 List.push_back(Object);
360
361 return Object;
362 }
363
364 /// This function takes a section data object from the assembler
365 /// and creates the associated COFF section staging object.
DefineSection(MCSectionData const & SectionData)366 void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
367 assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
368 && "Got non COFF section in the COFF backend!");
369 // FIXME: Not sure how to verify this (at least in a debug build).
370 MCSectionCOFF const &Sec =
371 static_cast<MCSectionCOFF const &>(SectionData.getSection());
372
373 COFFSection *coff_section = createSection(Sec.getSectionName());
374 COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
375
376 coff_section->Symbol = coff_symbol;
377 coff_symbol->Section = coff_section;
378 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
379
380 // In this case the auxiliary symbol is a Section Definition.
381 coff_symbol->Aux.resize(1);
382 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
383 coff_symbol->Aux[0].AuxType = ATSectionDefinition;
384 coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
385
386 coff_section->Header.Characteristics = Sec.getCharacteristics();
387
388 uint32_t &Characteristics = coff_section->Header.Characteristics;
389 switch (SectionData.getAlignment()) {
390 case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break;
391 case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break;
392 case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break;
393 case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break;
394 case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break;
395 case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break;
396 case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break;
397 case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break;
398 case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break;
399 case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break;
400 case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
401 case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
402 case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
403 case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
404 default:
405 llvm_unreachable("unsupported section alignment");
406 }
407
408 // Bind internal COFF section to MC section.
409 coff_section->MCData = &SectionData;
410 SectionMap[&SectionData.getSection()] = coff_section;
411 }
412
413 /// This function takes a section data object from the assembler
414 /// and creates the associated COFF symbol staging object.
DefineSymbol(MCSymbolData const & SymbolData,MCAssembler & Assembler)415 void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
416 MCAssembler &Assembler) {
417 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&SymbolData.getSymbol());
418
419 coff_symbol->Data.Type = (SymbolData.getFlags() & 0x0000FFFF) >> 0;
420 coff_symbol->Data.StorageClass = (SymbolData.getFlags() & 0x00FF0000) >> 16;
421
422 if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
423 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
424
425 if (SymbolData.getSymbol().isVariable()) {
426 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
427 const MCExpr *Value = SymbolData.getSymbol().getVariableValue();
428
429 // FIXME: This assert message isn't very good.
430 assert(Value->getKind() == MCExpr::SymbolRef &&
431 "Value must be a SymbolRef!");
432
433 const MCSymbolRefExpr *SymbolRef =
434 static_cast<const MCSymbolRefExpr *>(Value);
435 coff_symbol->Other = GetOrCreateCOFFSymbol(&SymbolRef->getSymbol());
436 } else {
437 std::string WeakName = std::string(".weak.")
438 + SymbolData.getSymbol().getName().str()
439 + ".default";
440 COFFSymbol *WeakDefault = createSymbol(WeakName);
441 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
442 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
443 WeakDefault->Data.Type = 0;
444 WeakDefault->Data.Value = 0;
445 coff_symbol->Other = WeakDefault;
446 }
447
448 // Setup the Weak External auxiliary symbol.
449 coff_symbol->Aux.resize(1);
450 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
451 coff_symbol->Aux[0].AuxType = ATWeakExternal;
452 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
453 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
454 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
455 }
456
457 // If no storage class was specified in the streamer, define it here.
458 if (coff_symbol->Data.StorageClass == 0) {
459 bool external = SymbolData.isExternal() || (SymbolData.Fragment == NULL);
460
461 coff_symbol->Data.StorageClass =
462 external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC;
463 }
464
465 if (SymbolData.Fragment != NULL)
466 coff_symbol->Section =
467 SectionMap[&SymbolData.Fragment->getParent()->getSection()];
468
469 // Bind internal COFF symbol to MC symbol.
470 coff_symbol->MCData = &SymbolData;
471 SymbolMap[&SymbolData.getSymbol()] = coff_symbol;
472 }
473
474 /// making a section real involves assigned it a number and putting
475 /// name into the string table if needed
MakeSectionReal(COFFSection & S,size_t Number)476 void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
477 if (S.Name.size() > COFF::NameSize) {
478 size_t StringTableEntry = Strings.insert(S.Name.c_str());
479
480 // FIXME: Why is this number 999999? This number is never mentioned in the
481 // spec. I'm assuming this is due to the printed value needing to fit into
482 // the S.Header.Name field. In which case why not 9999999 (7 9's instead of
483 // 6)? The spec does not state if this entry should be null terminated in
484 // this case, and thus this seems to be the best way to do it. I think I
485 // just solved my own FIXME...
486 if (StringTableEntry > 999999)
487 report_fatal_error("COFF string table is greater than 999999 bytes.");
488
489 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
490 } else
491 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
492
493 S.Number = Number;
494 S.Symbol->Data.SectionNumber = S.Number;
495 S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
496 }
497
MakeSymbolReal(COFFSymbol & S,size_t Index)498 void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
499 if (S.Name.size() > COFF::NameSize) {
500 size_t StringTableEntry = Strings.insert(S.Name.c_str());
501
502 S.set_name_offset(StringTableEntry);
503 } else
504 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
505 S.Index = Index;
506 }
507
ExportSection(COFFSection const * S)508 bool WinCOFFObjectWriter::ExportSection(COFFSection const *S) {
509 return !S->MCData->getFragmentList().empty();
510 }
511
ExportSymbol(MCSymbolData const & SymbolData,MCAssembler & Asm)512 bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
513 MCAssembler &Asm) {
514 // This doesn't seem to be right. Strings referred to from the .data section
515 // need symbols so they can be linked to code in the .text section right?
516
517 // return Asm.isSymbolLinkerVisible (&SymbolData);
518
519 // For now, all non-variable symbols are exported,
520 // the linker will sort the rest out for us.
521 return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable();
522 }
523
IsPhysicalSection(COFFSection * S)524 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
525 return (S->Header.Characteristics
526 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
527 }
528
529 //------------------------------------------------------------------------------
530 // entity writing methods
531
WriteFileHeader(const COFF::header & Header)532 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
533 WriteLE16(Header.Machine);
534 WriteLE16(Header.NumberOfSections);
535 WriteLE32(Header.TimeDateStamp);
536 WriteLE32(Header.PointerToSymbolTable);
537 WriteLE32(Header.NumberOfSymbols);
538 WriteLE16(Header.SizeOfOptionalHeader);
539 WriteLE16(Header.Characteristics);
540 }
541
WriteSymbol(const COFFSymbol * S)542 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
543 WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
544 WriteLE32(S->Data.Value);
545 WriteLE16(S->Data.SectionNumber);
546 WriteLE16(S->Data.Type);
547 Write8(S->Data.StorageClass);
548 Write8(S->Data.NumberOfAuxSymbols);
549 WriteAuxiliarySymbols(S->Aux);
550 }
551
WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols & S)552 void WinCOFFObjectWriter::WriteAuxiliarySymbols(
553 const COFFSymbol::AuxiliarySymbols &S) {
554 for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
555 i != e; ++i) {
556 switch(i->AuxType) {
557 case ATFunctionDefinition:
558 WriteLE32(i->Aux.FunctionDefinition.TagIndex);
559 WriteLE32(i->Aux.FunctionDefinition.TotalSize);
560 WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
561 WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
562 WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
563 break;
564 case ATbfAndefSymbol:
565 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
566 WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
567 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
568 WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
569 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
570 break;
571 case ATWeakExternal:
572 WriteLE32(i->Aux.WeakExternal.TagIndex);
573 WriteLE32(i->Aux.WeakExternal.Characteristics);
574 WriteZeros(sizeof(i->Aux.WeakExternal.unused));
575 break;
576 case ATFile:
577 WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
578 sizeof(i->Aux.File.FileName)));
579 break;
580 case ATSectionDefinition:
581 WriteLE32(i->Aux.SectionDefinition.Length);
582 WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
583 WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
584 WriteLE32(i->Aux.SectionDefinition.CheckSum);
585 WriteLE16(i->Aux.SectionDefinition.Number);
586 Write8(i->Aux.SectionDefinition.Selection);
587 WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
588 break;
589 }
590 }
591 }
592
WriteSectionHeader(const COFF::section & S)593 void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
594 WriteBytes(StringRef(S.Name, COFF::NameSize));
595
596 WriteLE32(S.VirtualSize);
597 WriteLE32(S.VirtualAddress);
598 WriteLE32(S.SizeOfRawData);
599 WriteLE32(S.PointerToRawData);
600 WriteLE32(S.PointerToRelocations);
601 WriteLE32(S.PointerToLineNumbers);
602 WriteLE16(S.NumberOfRelocations);
603 WriteLE16(S.NumberOfLineNumbers);
604 WriteLE32(S.Characteristics);
605 }
606
WriteRelocation(const COFF::relocation & R)607 void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
608 WriteLE32(R.VirtualAddress);
609 WriteLE32(R.SymbolTableIndex);
610 WriteLE16(R.Type);
611 }
612
613 ////////////////////////////////////////////////////////////////////////////////
614 // MCObjectWriter interface implementations
615
ExecutePostLayoutBinding(MCAssembler & Asm,const MCAsmLayout & Layout)616 void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
617 const MCAsmLayout &Layout) {
618 // "Define" each section & symbol. This creates section & symbol
619 // entries in the staging area.
620
621 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
622 DefineSection(*i);
623
624 for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
625 e = Asm.symbol_end(); i != e; i++) {
626 if (ExportSymbol(*i, Asm))
627 DefineSymbol(*i, Asm);
628 }
629 }
630
RecordRelocation(const MCAssembler & Asm,const MCAsmLayout & Layout,const MCFragment * Fragment,const MCFixup & Fixup,MCValue Target,uint64_t & FixedValue)631 void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
632 const MCAsmLayout &Layout,
633 const MCFragment *Fragment,
634 const MCFixup &Fixup,
635 MCValue Target,
636 uint64_t &FixedValue) {
637 assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
638
639 const MCSymbol *A = &Target.getSymA()->getSymbol();
640 MCSymbolData &A_SD = Asm.getSymbolData(*A);
641
642 MCSectionData const *SectionData = Fragment->getParent();
643
644 // Mark this symbol as requiring an entry in the symbol table.
645 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
646 "Section must already have been defined in ExecutePostLayoutBinding!");
647 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
648 "Symbol must already have been defined in ExecutePostLayoutBinding!");
649
650 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
651 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
652 const MCSymbolRefExpr *SymA = Target.getSymA();
653 const MCSymbolRefExpr *SymB = Target.getSymB();
654 const bool CrossSection = SymB &&
655 &SymA->getSymbol().getSection() != &SymB->getSymbol().getSection();
656
657 if (Target.getSymB()) {
658 const MCSymbol *B = &Target.getSymB()->getSymbol();
659 MCSymbolData &B_SD = Asm.getSymbolData(*B);
660
661 // Offset of the symbol in the section
662 int64_t a = Layout.getSymbolOffset(&B_SD);
663
664 // Ofeset of the relocation in the section
665 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
666
667 FixedValue = b - a;
668 // In the case where we have SymbA and SymB, we just need to store the delta
669 // between the two symbols. Update FixedValue to account for the delta, and
670 // skip recording the relocation.
671 if (!CrossSection)
672 return;
673 } else {
674 FixedValue = Target.getConstant();
675 }
676
677 COFFRelocation Reloc;
678
679 Reloc.Data.SymbolTableIndex = 0;
680 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
681
682 // Turn relocations for temporary symbols into section relocations.
683 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
684 Reloc.Symb = coff_symbol->Section->Symbol;
685 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
686 + coff_symbol->MCData->getOffset();
687 } else
688 Reloc.Symb = coff_symbol;
689
690 ++Reloc.Symb->Relocations;
691
692 Reloc.Data.VirtualAddress += Fixup.getOffset();
693
694 unsigned FixupKind = Fixup.getKind();
695
696 if (CrossSection)
697 FixupKind = FK_PCRel_4;
698
699 Reloc.Data.Type = TargetObjectWriter->getRelocType(FixupKind);
700
701 // FIXME: Can anyone explain what this does other than adjust for the size
702 // of the offset?
703 if (Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32 ||
704 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32)
705 FixedValue += 4;
706
707 coff_section->Relocations.push_back(Reloc);
708 }
709
WriteObject(MCAssembler & Asm,const MCAsmLayout & Layout)710 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
711 const MCAsmLayout &Layout) {
712 // Assign symbol and section indexes and offsets.
713 Header.NumberOfSections = 0;
714
715 for (sections::iterator i = Sections.begin(),
716 e = Sections.end(); i != e; i++) {
717 if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
718 MakeSectionReal(**i, ++Header.NumberOfSections);
719 } else {
720 (*i)->Number = -1;
721 }
722 }
723
724 Header.NumberOfSymbols = 0;
725
726 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
727 COFFSymbol *coff_symbol = *i;
728 MCSymbolData const *SymbolData = coff_symbol->MCData;
729
730 // Update section number & offset for symbols that have them.
731 if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
732 assert(coff_symbol->Section != NULL);
733
734 coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
735 coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
736 + SymbolData->Offset;
737 }
738
739 if (coff_symbol->should_keep()) {
740 MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
741
742 // Update auxiliary symbol info.
743 coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
744 Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
745 } else
746 coff_symbol->Index = -1;
747 }
748
749 // Fixup weak external references.
750 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
751 COFFSymbol *coff_symbol = *i;
752 if (coff_symbol->Other != NULL) {
753 assert(coff_symbol->Index != -1);
754 assert(coff_symbol->Aux.size() == 1 &&
755 "Symbol must contain one aux symbol!");
756 assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
757 "Symbol's aux symbol must be a Weak External!");
758 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
759 }
760 }
761
762 // Assign file offsets to COFF object file structures.
763
764 unsigned offset = 0;
765
766 offset += COFF::HeaderSize;
767 offset += COFF::SectionSize * Header.NumberOfSections;
768
769 for (MCAssembler::const_iterator i = Asm.begin(),
770 e = Asm.end();
771 i != e; i++) {
772 COFFSection *Sec = SectionMap[&i->getSection()];
773
774 if (Sec->Number == -1)
775 continue;
776
777 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);
778
779 if (IsPhysicalSection(Sec)) {
780 Sec->Header.PointerToRawData = offset;
781
782 offset += Sec->Header.SizeOfRawData;
783 }
784
785 if (Sec->Relocations.size() > 0) {
786 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
787
788 if (RelocationsOverflow) {
789 // Signal overflow by setting NumberOfSections to max value. Actual
790 // size is found in reloc #0. Microsoft tools understand this.
791 Sec->Header.NumberOfRelocations = 0xffff;
792 } else {
793 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
794 }
795 Sec->Header.PointerToRelocations = offset;
796
797 if (RelocationsOverflow) {
798 // Reloc #0 will contain actual count, so make room for it.
799 offset += COFF::RelocationSize;
800 }
801
802 offset += COFF::RelocationSize * Sec->Relocations.size();
803
804 for (relocations::iterator cr = Sec->Relocations.begin(),
805 er = Sec->Relocations.end();
806 cr != er; ++cr) {
807 assert((*cr).Symb->Index != -1);
808 (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
809 }
810 }
811
812 assert(Sec->Symbol->Aux.size() == 1
813 && "Section's symbol must have one aux!");
814 AuxSymbol &Aux = Sec->Symbol->Aux[0];
815 assert(Aux.AuxType == ATSectionDefinition &&
816 "Section's symbol's aux symbol must be a Section Definition!");
817 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
818 Aux.Aux.SectionDefinition.NumberOfRelocations =
819 Sec->Header.NumberOfRelocations;
820 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
821 Sec->Header.NumberOfLineNumbers;
822 }
823
824 Header.PointerToSymbolTable = offset;
825
826 Header.TimeDateStamp = sys::TimeValue::now().toEpochTime();
827
828 // Write it all to disk...
829 WriteFileHeader(Header);
830
831 {
832 sections::iterator i, ie;
833 MCAssembler::const_iterator j, je;
834
835 for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
836 if ((*i)->Number != -1) {
837 if ((*i)->Relocations.size() >= 0xffff) {
838 (*i)->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
839 }
840 WriteSectionHeader((*i)->Header);
841 }
842
843 for (i = Sections.begin(), ie = Sections.end(),
844 j = Asm.begin(), je = Asm.end();
845 (i != ie) && (j != je); ++i, ++j) {
846
847 if ((*i)->Number == -1)
848 continue;
849
850 if ((*i)->Header.PointerToRawData != 0) {
851 assert(OS.tell() == (*i)->Header.PointerToRawData &&
852 "Section::PointerToRawData is insane!");
853
854 Asm.writeSectionData(j, Layout);
855 }
856
857 if ((*i)->Relocations.size() > 0) {
858 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
859 "Section::PointerToRelocations is insane!");
860
861 if ((*i)->Relocations.size() >= 0xffff) {
862 // In case of overflow, write actual relocation count as first
863 // relocation. Including the synthetic reloc itself (+ 1).
864 COFF::relocation r;
865 r.VirtualAddress = (*i)->Relocations.size() + 1;
866 r.SymbolTableIndex = 0;
867 r.Type = 0;
868 WriteRelocation(r);
869 }
870
871 for (relocations::const_iterator k = (*i)->Relocations.begin(),
872 ke = (*i)->Relocations.end();
873 k != ke; k++) {
874 WriteRelocation(k->Data);
875 }
876 } else
877 assert((*i)->Header.PointerToRelocations == 0 &&
878 "Section::PointerToRelocations is insane!");
879 }
880 }
881
882 assert(OS.tell() == Header.PointerToSymbolTable &&
883 "Header::PointerToSymbolTable is insane!");
884
885 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
886 if ((*i)->Index != -1)
887 WriteSymbol(*i);
888
889 OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
890 }
891
MCWinCOFFObjectTargetWriter(unsigned Machine_)892 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :
893 Machine(Machine_) {
894 }
895
896 //------------------------------------------------------------------------------
897 // WinCOFFObjectWriter factory function
898
899 namespace llvm {
createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter * MOTW,raw_ostream & OS)900 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
901 raw_ostream &OS) {
902 return new WinCOFFObjectWriter(MOTW, OS);
903 }
904 }
905