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
26 #include "llvm/ADT/DenseMap.h"
27 #include "llvm/ADT/StringMap.h"
28 #include "llvm/ADT/StringRef.h"
29
30 #include "llvm/Support/COFF.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Support/ErrorHandling.h"
33
34 #include "llvm/Support/TimeValue.h"
35
36 #include "../Target/X86/MCTargetDesc/X86FixupKinds.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__anon8d2f65060111::COFFRelocation88 COFFRelocation() : Symb(NULL) {}
size__anon8d2f65060111::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 // Root level file contents.
132 bool Is64Bit;
133 COFF::header Header;
134 sections Sections;
135 symbols Symbols;
136 StringTable Strings;
137
138 // Maps used during object file creation.
139 section_map SectionMap;
140 symbol_map SymbolMap;
141
142 WinCOFFObjectWriter(raw_ostream &OS, bool is64Bit);
143 ~WinCOFFObjectWriter();
144
145 COFFSymbol *createSymbol(StringRef Name);
146 COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol);
147 COFFSection *createSection(StringRef Name);
148
149 template <typename object_t, typename list_t>
150 object_t *createCOFFEntity(llvm::StringRef Name, list_t &List);
151
152 void DefineSection(MCSectionData const &SectionData);
153 void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler);
154
155 void MakeSymbolReal(COFFSymbol &S, size_t Index);
156 void MakeSectionReal(COFFSection &S, size_t Number);
157
158 bool ExportSection(COFFSection const *S);
159 bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm);
160
161 bool IsPhysicalSection(COFFSection *S);
162
163 // Entity writing methods.
164
165 void WriteFileHeader(const COFF::header &Header);
166 void WriteSymbol(const COFFSymbol *S);
167 void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
168 void WriteSectionHeader(const COFF::section &S);
169 void WriteRelocation(const COFF::relocation &R);
170
171 // MCObjectWriter interface implementation.
172
173 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout);
174
175 void RecordRelocation(const MCAssembler &Asm,
176 const MCAsmLayout &Layout,
177 const MCFragment *Fragment,
178 const MCFixup &Fixup,
179 MCValue Target,
180 uint64_t &FixedValue);
181
182 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
183 };
184 }
185
write_uint32_le(void * Data,uint32_t const & Value)186 static inline void write_uint32_le(void *Data, uint32_t const &Value) {
187 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
188 Ptr[0] = (Value & 0x000000FF) >> 0;
189 Ptr[1] = (Value & 0x0000FF00) >> 8;
190 Ptr[2] = (Value & 0x00FF0000) >> 16;
191 Ptr[3] = (Value & 0xFF000000) >> 24;
192 }
193
write_uint16_le(void * Data,uint16_t const & Value)194 static inline void write_uint16_le(void *Data, uint16_t const &Value) {
195 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
196 Ptr[0] = (Value & 0x00FF) >> 0;
197 Ptr[1] = (Value & 0xFF00) >> 8;
198 }
199
write_uint8_le(void * Data,uint8_t const & Value)200 static inline void write_uint8_le(void *Data, uint8_t const &Value) {
201 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
202 Ptr[0] = (Value & 0xFF) >> 0;
203 }
204
205 //------------------------------------------------------------------------------
206 // Symbol class implementation
207
COFFSymbol(llvm::StringRef name)208 COFFSymbol::COFFSymbol(llvm::StringRef name)
209 : Name(name.begin(), name.end())
210 , Other(NULL)
211 , Section(NULL)
212 , Relocations(0)
213 , MCData(NULL) {
214 memset(&Data, 0, sizeof(Data));
215 }
216
size() const217 size_t COFFSymbol::size() const {
218 return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
219 }
220
221 // In the case that the name does not fit within 8 bytes, the offset
222 // into the string table is stored in the last 4 bytes instead, leaving
223 // the first 4 bytes as 0.
set_name_offset(uint32_t Offset)224 void COFFSymbol::set_name_offset(uint32_t Offset) {
225 write_uint32_le(Data.Name + 0, 0);
226 write_uint32_le(Data.Name + 4, Offset);
227 }
228
229 /// logic to decide if the symbol should be reported in the symbol table
should_keep() const230 bool COFFSymbol::should_keep() const {
231 // no section means its external, keep it
232 if (Section == NULL)
233 return true;
234
235 // if it has relocations pointing at it, keep it
236 if (Relocations > 0) {
237 assert(Section->Number != -1 && "Sections with relocations must be real!");
238 return true;
239 }
240
241 // if the section its in is being droped, drop it
242 if (Section->Number == -1)
243 return false;
244
245 // if it is the section symbol, keep it
246 if (Section->Symbol == this)
247 return true;
248
249 // if its temporary, drop it
250 if (MCData && MCData->getSymbol().isTemporary())
251 return false;
252
253 // otherwise, keep it
254 return true;
255 }
256
257 //------------------------------------------------------------------------------
258 // Section class implementation
259
COFFSection(llvm::StringRef name)260 COFFSection::COFFSection(llvm::StringRef name)
261 : Name(name)
262 , MCData(NULL)
263 , Symbol(NULL) {
264 memset(&Header, 0, sizeof(Header));
265 }
266
size()267 size_t COFFSection::size() {
268 return COFF::SectionSize;
269 }
270
271 //------------------------------------------------------------------------------
272 // StringTable class implementation
273
274 /// Write the length of the string table into Data.
275 /// The length of the string table includes uint32 length header.
update_length()276 void StringTable::update_length() {
277 write_uint32_le(&Data.front(), Data.size());
278 }
279
StringTable()280 StringTable::StringTable() {
281 // The string table data begins with the length of the entire string table
282 // including the length header. Allocate space for this header.
283 Data.resize(4);
284 }
285
size() const286 size_t StringTable::size() const {
287 return Data.size();
288 }
289
290 /// Add String to the table iff it is not already there.
291 /// @returns the index into the string table where the string is now located.
insert(llvm::StringRef String)292 size_t StringTable::insert(llvm::StringRef String) {
293 map::iterator i = Map.find(String);
294
295 if (i != Map.end())
296 return i->second;
297
298 size_t Offset = Data.size();
299
300 // Insert string data into string table.
301 Data.insert(Data.end(), String.begin(), String.end());
302 Data.push_back('\0');
303
304 // Put a reference to it in the map.
305 Map[String] = Offset;
306
307 // Update the internal length field.
308 update_length();
309
310 return Offset;
311 }
312
313 //------------------------------------------------------------------------------
314 // WinCOFFObjectWriter class implementation
315
WinCOFFObjectWriter(raw_ostream & OS,bool is64Bit)316 WinCOFFObjectWriter::WinCOFFObjectWriter(raw_ostream &OS, bool is64Bit)
317 : MCObjectWriter(OS, true)
318 , Is64Bit(is64Bit) {
319 memset(&Header, 0, sizeof(Header));
320
321 Is64Bit ? Header.Machine = COFF::IMAGE_FILE_MACHINE_AMD64
322 : Header.Machine = COFF::IMAGE_FILE_MACHINE_I386;
323 }
324
~WinCOFFObjectWriter()325 WinCOFFObjectWriter::~WinCOFFObjectWriter() {
326 for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I)
327 delete *I;
328 for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I)
329 delete *I;
330 }
331
createSymbol(StringRef Name)332 COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
333 return createCOFFEntity<COFFSymbol>(Name, Symbols);
334 }
335
GetOrCreateCOFFSymbol(const MCSymbol * Symbol)336 COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
337 symbol_map::iterator i = SymbolMap.find(Symbol);
338 if (i != SymbolMap.end())
339 return i->second;
340 COFFSymbol *RetSymbol
341 = createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
342 SymbolMap[Symbol] = RetSymbol;
343 return RetSymbol;
344 }
345
createSection(llvm::StringRef Name)346 COFFSection *WinCOFFObjectWriter::createSection(llvm::StringRef Name) {
347 return createCOFFEntity<COFFSection>(Name, Sections);
348 }
349
350 /// A template used to lookup or create a symbol/section, and initialize it if
351 /// needed.
352 template <typename object_t, typename list_t>
createCOFFEntity(llvm::StringRef Name,list_t & List)353 object_t *WinCOFFObjectWriter::createCOFFEntity(llvm::StringRef Name,
354 list_t &List) {
355 object_t *Object = new object_t(Name);
356
357 List.push_back(Object);
358
359 return Object;
360 }
361
362 /// This function takes a section data object from the assembler
363 /// and creates the associated COFF section staging object.
DefineSection(MCSectionData const & SectionData)364 void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
365 assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
366 && "Got non COFF section in the COFF backend!");
367 // FIXME: Not sure how to verify this (at least in a debug build).
368 MCSectionCOFF const &Sec =
369 static_cast<MCSectionCOFF const &>(SectionData.getSection());
370
371 COFFSection *coff_section = createSection(Sec.getSectionName());
372 COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
373
374 coff_section->Symbol = coff_symbol;
375 coff_symbol->Section = coff_section;
376 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
377
378 // In this case the auxiliary symbol is a Section Definition.
379 coff_symbol->Aux.resize(1);
380 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
381 coff_symbol->Aux[0].AuxType = ATSectionDefinition;
382 coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
383
384 coff_section->Header.Characteristics = Sec.getCharacteristics();
385
386 uint32_t &Characteristics = coff_section->Header.Characteristics;
387 switch (SectionData.getAlignment()) {
388 case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break;
389 case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break;
390 case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break;
391 case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break;
392 case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break;
393 case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break;
394 case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break;
395 case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break;
396 case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break;
397 case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break;
398 case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
399 case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
400 case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
401 case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
402 default:
403 llvm_unreachable("unsupported section alignment");
404 }
405
406 // Bind internal COFF section to MC section.
407 coff_section->MCData = &SectionData;
408 SectionMap[&SectionData.getSection()] = coff_section;
409 }
410
411 /// This function takes a section data object from the assembler
412 /// and creates the associated COFF symbol staging object.
DefineSymbol(MCSymbolData const & SymbolData,MCAssembler & Assembler)413 void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
414 MCAssembler &Assembler) {
415 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&SymbolData.getSymbol());
416
417 coff_symbol->Data.Type = (SymbolData.getFlags() & 0x0000FFFF) >> 0;
418 coff_symbol->Data.StorageClass = (SymbolData.getFlags() & 0x00FF0000) >> 16;
419
420 if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
421 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
422
423 if (SymbolData.getSymbol().isVariable()) {
424 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
425 const MCExpr *Value = SymbolData.getSymbol().getVariableValue();
426
427 // FIXME: This assert message isn't very good.
428 assert(Value->getKind() == MCExpr::SymbolRef &&
429 "Value must be a SymbolRef!");
430
431 const MCSymbolRefExpr *SymbolRef =
432 static_cast<const MCSymbolRefExpr *>(Value);
433 coff_symbol->Other = GetOrCreateCOFFSymbol(&SymbolRef->getSymbol());
434 } else {
435 std::string WeakName = std::string(".weak.")
436 + SymbolData.getSymbol().getName().str()
437 + ".default";
438 COFFSymbol *WeakDefault = createSymbol(WeakName);
439 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
440 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
441 WeakDefault->Data.Type = 0;
442 WeakDefault->Data.Value = 0;
443 coff_symbol->Other = WeakDefault;
444 }
445
446 // Setup the Weak External auxiliary symbol.
447 coff_symbol->Aux.resize(1);
448 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
449 coff_symbol->Aux[0].AuxType = ATWeakExternal;
450 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
451 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
452 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
453 }
454
455 // If no storage class was specified in the streamer, define it here.
456 if (coff_symbol->Data.StorageClass == 0) {
457 bool external = SymbolData.isExternal() || (SymbolData.Fragment == NULL);
458
459 coff_symbol->Data.StorageClass =
460 external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC;
461 }
462
463 if (SymbolData.Fragment != NULL)
464 coff_symbol->Section =
465 SectionMap[&SymbolData.Fragment->getParent()->getSection()];
466
467 // Bind internal COFF symbol to MC symbol.
468 coff_symbol->MCData = &SymbolData;
469 SymbolMap[&SymbolData.getSymbol()] = coff_symbol;
470 }
471
472 /// making a section real involves assigned it a number and putting
473 /// name into the string table if needed
MakeSectionReal(COFFSection & S,size_t Number)474 void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
475 if (S.Name.size() > COFF::NameSize) {
476 size_t StringTableEntry = Strings.insert(S.Name.c_str());
477
478 // FIXME: Why is this number 999999? This number is never mentioned in the
479 // spec. I'm assuming this is due to the printed value needing to fit into
480 // the S.Header.Name field. In which case why not 9999999 (7 9's instead of
481 // 6)? The spec does not state if this entry should be null terminated in
482 // this case, and thus this seems to be the best way to do it. I think I
483 // just solved my own FIXME...
484 if (StringTableEntry > 999999)
485 report_fatal_error("COFF string table is greater than 999999 bytes.");
486
487 #if defined(__ANDROID__) || defined(ANDROID)
488 // bionic defines sprintf as __builtin___sprintf_chk, which is not available
489 // in std.
490 sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
491 #else
492 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
493 #endif
494 } else
495 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
496
497 S.Number = Number;
498 S.Symbol->Data.SectionNumber = S.Number;
499 S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
500 }
501
MakeSymbolReal(COFFSymbol & S,size_t Index)502 void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
503 if (S.Name.size() > COFF::NameSize) {
504 size_t StringTableEntry = Strings.insert(S.Name.c_str());
505
506 S.set_name_offset(StringTableEntry);
507 } else
508 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
509 S.Index = Index;
510 }
511
ExportSection(COFFSection const * S)512 bool WinCOFFObjectWriter::ExportSection(COFFSection const *S) {
513 return !S->MCData->getFragmentList().empty();
514 }
515
ExportSymbol(MCSymbolData const & SymbolData,MCAssembler & Asm)516 bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
517 MCAssembler &Asm) {
518 // This doesn't seem to be right. Strings referred to from the .data section
519 // need symbols so they can be linked to code in the .text section right?
520
521 // return Asm.isSymbolLinkerVisible (&SymbolData);
522
523 // For now, all non-variable symbols are exported,
524 // the linker will sort the rest out for us.
525 return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable();
526 }
527
IsPhysicalSection(COFFSection * S)528 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
529 return (S->Header.Characteristics
530 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
531 }
532
533 //------------------------------------------------------------------------------
534 // entity writing methods
535
WriteFileHeader(const COFF::header & Header)536 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
537 WriteLE16(Header.Machine);
538 WriteLE16(Header.NumberOfSections);
539 WriteLE32(Header.TimeDateStamp);
540 WriteLE32(Header.PointerToSymbolTable);
541 WriteLE32(Header.NumberOfSymbols);
542 WriteLE16(Header.SizeOfOptionalHeader);
543 WriteLE16(Header.Characteristics);
544 }
545
WriteSymbol(const COFFSymbol * S)546 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
547 WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
548 WriteLE32(S->Data.Value);
549 WriteLE16(S->Data.SectionNumber);
550 WriteLE16(S->Data.Type);
551 Write8(S->Data.StorageClass);
552 Write8(S->Data.NumberOfAuxSymbols);
553 WriteAuxiliarySymbols(S->Aux);
554 }
555
WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols & S)556 void WinCOFFObjectWriter::WriteAuxiliarySymbols(
557 const COFFSymbol::AuxiliarySymbols &S) {
558 for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
559 i != e; ++i) {
560 switch(i->AuxType) {
561 case ATFunctionDefinition:
562 WriteLE32(i->Aux.FunctionDefinition.TagIndex);
563 WriteLE32(i->Aux.FunctionDefinition.TotalSize);
564 WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
565 WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
566 WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
567 break;
568 case ATbfAndefSymbol:
569 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
570 WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
571 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
572 WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
573 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
574 break;
575 case ATWeakExternal:
576 WriteLE32(i->Aux.WeakExternal.TagIndex);
577 WriteLE32(i->Aux.WeakExternal.Characteristics);
578 WriteZeros(sizeof(i->Aux.WeakExternal.unused));
579 break;
580 case ATFile:
581 WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
582 sizeof(i->Aux.File.FileName)));
583 break;
584 case ATSectionDefinition:
585 WriteLE32(i->Aux.SectionDefinition.Length);
586 WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
587 WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
588 WriteLE32(i->Aux.SectionDefinition.CheckSum);
589 WriteLE16(i->Aux.SectionDefinition.Number);
590 Write8(i->Aux.SectionDefinition.Selection);
591 WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
592 break;
593 }
594 }
595 }
596
WriteSectionHeader(const COFF::section & S)597 void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
598 WriteBytes(StringRef(S.Name, COFF::NameSize));
599
600 WriteLE32(S.VirtualSize);
601 WriteLE32(S.VirtualAddress);
602 WriteLE32(S.SizeOfRawData);
603 WriteLE32(S.PointerToRawData);
604 WriteLE32(S.PointerToRelocations);
605 WriteLE32(S.PointerToLineNumbers);
606 WriteLE16(S.NumberOfRelocations);
607 WriteLE16(S.NumberOfLineNumbers);
608 WriteLE32(S.Characteristics);
609 }
610
WriteRelocation(const COFF::relocation & R)611 void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
612 WriteLE32(R.VirtualAddress);
613 WriteLE32(R.SymbolTableIndex);
614 WriteLE16(R.Type);
615 }
616
617 ////////////////////////////////////////////////////////////////////////////////
618 // MCObjectWriter interface implementations
619
ExecutePostLayoutBinding(MCAssembler & Asm,const MCAsmLayout & Layout)620 void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
621 const MCAsmLayout &Layout) {
622 // "Define" each section & symbol. This creates section & symbol
623 // entries in the staging area.
624
625 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
626 DefineSection(*i);
627
628 for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
629 e = Asm.symbol_end(); i != e; i++) {
630 if (ExportSymbol(*i, Asm))
631 DefineSymbol(*i, Asm);
632 }
633 }
634
RecordRelocation(const MCAssembler & Asm,const MCAsmLayout & Layout,const MCFragment * Fragment,const MCFixup & Fixup,MCValue Target,uint64_t & FixedValue)635 void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
636 const MCAsmLayout &Layout,
637 const MCFragment *Fragment,
638 const MCFixup &Fixup,
639 MCValue Target,
640 uint64_t &FixedValue) {
641 assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
642
643 const MCSymbol *A = &Target.getSymA()->getSymbol();
644 MCSymbolData &A_SD = Asm.getSymbolData(*A);
645
646 MCSectionData const *SectionData = Fragment->getParent();
647
648 // Mark this symbol as requiring an entry in the symbol table.
649 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
650 "Section must already have been defined in ExecutePostLayoutBinding!");
651 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
652 "Symbol must already have been defined in ExecutePostLayoutBinding!");
653
654 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
655 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
656 const MCSymbolRefExpr *SymA = Target.getSymA();
657 const MCSymbolRefExpr *SymB = Target.getSymB();
658 const bool CrossSection = SymB &&
659 &SymA->getSymbol().getSection() != &SymB->getSymbol().getSection();
660
661 if (Target.getSymB()) {
662 const MCSymbol *B = &Target.getSymB()->getSymbol();
663 MCSymbolData &B_SD = Asm.getSymbolData(*B);
664
665 // Offset of the symbol in the section
666 int64_t a = Layout.getSymbolOffset(&B_SD);
667
668 // Ofeset of the relocation in the section
669 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
670
671 FixedValue = b - a;
672 // In the case where we have SymbA and SymB, we just need to store the delta
673 // between the two symbols. Update FixedValue to account for the delta, and
674 // skip recording the relocation.
675 if (!CrossSection)
676 return;
677 } else {
678 FixedValue = Target.getConstant();
679 }
680
681 COFFRelocation Reloc;
682
683 Reloc.Data.SymbolTableIndex = 0;
684 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
685
686 // Turn relocations for temporary symbols into section relocations.
687 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
688 Reloc.Symb = coff_symbol->Section->Symbol;
689 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
690 + coff_symbol->MCData->getOffset();
691 } else
692 Reloc.Symb = coff_symbol;
693
694 ++Reloc.Symb->Relocations;
695
696 Reloc.Data.VirtualAddress += Fixup.getOffset();
697
698 unsigned FixupKind = Fixup.getKind();
699
700 if (CrossSection)
701 FixupKind = FK_PCRel_4;
702
703 switch (FixupKind) {
704 case FK_PCRel_4:
705 case X86::reloc_riprel_4byte:
706 case X86::reloc_riprel_4byte_movq_load:
707 Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_REL32
708 : COFF::IMAGE_REL_I386_REL32;
709 // FIXME: Can anyone explain what this does other than adjust for the size
710 // of the offset?
711 FixedValue += 4;
712 break;
713 case FK_Data_4:
714 case X86::reloc_signed_4byte:
715 Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_ADDR32
716 : COFF::IMAGE_REL_I386_DIR32;
717 break;
718 case FK_Data_8:
719 if (Is64Bit)
720 Reloc.Data.Type = COFF::IMAGE_REL_AMD64_ADDR64;
721 else
722 llvm_unreachable("unsupported relocation type");
723 break;
724 default:
725 llvm_unreachable("unsupported relocation type");
726 }
727
728 coff_section->Relocations.push_back(Reloc);
729 }
730
WriteObject(MCAssembler & Asm,const MCAsmLayout & Layout)731 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
732 const MCAsmLayout &Layout) {
733 // Assign symbol and section indexes and offsets.
734 Header.NumberOfSections = 0;
735
736 for (sections::iterator i = Sections.begin(),
737 e = Sections.end(); i != e; i++) {
738 if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
739 MakeSectionReal(**i, ++Header.NumberOfSections);
740 } else {
741 (*i)->Number = -1;
742 }
743 }
744
745 Header.NumberOfSymbols = 0;
746
747 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
748 COFFSymbol *coff_symbol = *i;
749 MCSymbolData const *SymbolData = coff_symbol->MCData;
750
751 // Update section number & offset for symbols that have them.
752 if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
753 assert(coff_symbol->Section != NULL);
754
755 coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
756 coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
757 + SymbolData->Offset;
758 }
759
760 if (coff_symbol->should_keep()) {
761 MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
762
763 // Update auxiliary symbol info.
764 coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
765 Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
766 } else
767 coff_symbol->Index = -1;
768 }
769
770 // Fixup weak external references.
771 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
772 COFFSymbol *coff_symbol = *i;
773 if (coff_symbol->Other != NULL) {
774 assert(coff_symbol->Index != -1);
775 assert(coff_symbol->Aux.size() == 1 &&
776 "Symbol must contain one aux symbol!");
777 assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
778 "Symbol's aux symbol must be a Weak External!");
779 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
780 }
781 }
782
783 // Assign file offsets to COFF object file structures.
784
785 unsigned offset = 0;
786
787 offset += COFF::HeaderSize;
788 offset += COFF::SectionSize * Header.NumberOfSections;
789
790 for (MCAssembler::const_iterator i = Asm.begin(),
791 e = Asm.end();
792 i != e; i++) {
793 COFFSection *Sec = SectionMap[&i->getSection()];
794
795 if (Sec->Number == -1)
796 continue;
797
798 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);
799
800 if (IsPhysicalSection(Sec)) {
801 Sec->Header.PointerToRawData = offset;
802
803 offset += Sec->Header.SizeOfRawData;
804 }
805
806 if (Sec->Relocations.size() > 0) {
807 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
808 Sec->Header.PointerToRelocations = offset;
809
810 offset += COFF::RelocationSize * Sec->Relocations.size();
811
812 for (relocations::iterator cr = Sec->Relocations.begin(),
813 er = Sec->Relocations.end();
814 cr != er; ++cr) {
815 assert((*cr).Symb->Index != -1);
816 (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
817 }
818 }
819
820 assert(Sec->Symbol->Aux.size() == 1
821 && "Section's symbol must have one aux!");
822 AuxSymbol &Aux = Sec->Symbol->Aux[0];
823 assert(Aux.AuxType == ATSectionDefinition &&
824 "Section's symbol's aux symbol must be a Section Definition!");
825 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
826 Aux.Aux.SectionDefinition.NumberOfRelocations =
827 Sec->Header.NumberOfRelocations;
828 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
829 Sec->Header.NumberOfLineNumbers;
830 }
831
832 Header.PointerToSymbolTable = offset;
833
834 Header.TimeDateStamp = sys::TimeValue::now().toEpochTime();
835
836 // Write it all to disk...
837 WriteFileHeader(Header);
838
839 {
840 sections::iterator i, ie;
841 MCAssembler::const_iterator j, je;
842
843 for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
844 if ((*i)->Number != -1)
845 WriteSectionHeader((*i)->Header);
846
847 for (i = Sections.begin(), ie = Sections.end(),
848 j = Asm.begin(), je = Asm.end();
849 (i != ie) && (j != je); ++i, ++j) {
850
851 if ((*i)->Number == -1)
852 continue;
853
854 if ((*i)->Header.PointerToRawData != 0) {
855 assert(OS.tell() == (*i)->Header.PointerToRawData &&
856 "Section::PointerToRawData is insane!");
857
858 Asm.WriteSectionData(j, Layout);
859 }
860
861 if ((*i)->Relocations.size() > 0) {
862 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
863 "Section::PointerToRelocations is insane!");
864
865 for (relocations::const_iterator k = (*i)->Relocations.begin(),
866 ke = (*i)->Relocations.end();
867 k != ke; k++) {
868 WriteRelocation(k->Data);
869 }
870 } else
871 assert((*i)->Header.PointerToRelocations == 0 &&
872 "Section::PointerToRelocations is insane!");
873 }
874 }
875
876 assert(OS.tell() == Header.PointerToSymbolTable &&
877 "Header::PointerToSymbolTable is insane!");
878
879 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
880 if ((*i)->Index != -1)
881 WriteSymbol(*i);
882
883 OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
884 }
885
886 //------------------------------------------------------------------------------
887 // WinCOFFObjectWriter factory function
888
889 namespace llvm {
createWinCOFFObjectWriter(raw_ostream & OS,bool is64Bit)890 MCObjectWriter *createWinCOFFObjectWriter(raw_ostream &OS, bool is64Bit) {
891 return new WinCOFFObjectWriter(OS, is64Bit);
892 }
893 }
894