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/MCWinCOFFObjectWriter.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/OwningPtr.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/StringRef.h"
21 #include "llvm/MC/MCAsmLayout.h"
22 #include "llvm/MC/MCAssembler.h"
23 #include "llvm/MC/MCContext.h"
24 #include "llvm/MC/MCExpr.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/MCValue.h"
30 #include "llvm/Support/COFF.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Support/ErrorHandling.h"
33 #include "llvm/Support/TimeValue.h"
34 #include <cstdio>
35
36 using namespace llvm;
37
38 namespace {
39 typedef SmallString<COFF::NameSize> name;
40
41 enum AuxiliaryType {
42 ATFunctionDefinition,
43 ATbfAndefSymbol,
44 ATWeakExternal,
45 ATFile,
46 ATSectionDefinition
47 };
48
49 struct AuxSymbol {
50 AuxiliaryType AuxType;
51 COFF::Auxiliary Aux;
52 };
53
54 class COFFSymbol;
55 class COFFSection;
56
57 class COFFSymbol {
58 public:
59 COFF::symbol Data;
60
61 typedef SmallVector<AuxSymbol, 1> AuxiliarySymbols;
62
63 name Name;
64 int Index;
65 AuxiliarySymbols Aux;
66 COFFSymbol *Other;
67 COFFSection *Section;
68 int Relocations;
69
70 MCSymbolData const *MCData;
71
72 COFFSymbol(StringRef name);
73 size_t size() const;
74 void set_name_offset(uint32_t Offset);
75
76 bool should_keep() const;
77 };
78
79 // This class contains staging data for a COFF relocation entry.
80 struct COFFRelocation {
81 COFF::relocation Data;
82 COFFSymbol *Symb;
83
COFFRelocation__anon094d99f70111::COFFRelocation84 COFFRelocation() : Symb(NULL) {}
size__anon094d99f70111::COFFRelocation85 static size_t size() { return COFF::RelocationSize; }
86 };
87
88 typedef std::vector<COFFRelocation> relocations;
89
90 class COFFSection {
91 public:
92 COFF::section Header;
93
94 std::string Name;
95 int Number;
96 MCSectionData const *MCData;
97 COFFSymbol *Symbol;
98 relocations Relocations;
99
100 COFFSection(StringRef name);
101 static size_t size();
102 };
103
104 // This class holds the COFF string table.
105 class StringTable {
106 typedef StringMap<size_t> map;
107 map Map;
108
109 void update_length();
110 public:
111 std::vector<char> Data;
112
113 StringTable();
114 size_t size() const;
115 size_t insert(StringRef String);
116 };
117
118 class WinCOFFObjectWriter : public MCObjectWriter {
119 public:
120
121 typedef std::vector<COFFSymbol*> symbols;
122 typedef std::vector<COFFSection*> sections;
123
124 typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map;
125 typedef DenseMap<MCSection const *, COFFSection *> section_map;
126
127 llvm::OwningPtr<MCWinCOFFObjectTargetWriter> TargetObjectWriter;
128
129 // Root level file contents.
130 COFF::header Header;
131 sections Sections;
132 symbols Symbols;
133 StringTable Strings;
134
135 // Maps used during object file creation.
136 section_map SectionMap;
137 symbol_map SymbolMap;
138
139 WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, raw_ostream &OS);
140 ~WinCOFFObjectWriter();
141
142 COFFSymbol *createSymbol(StringRef Name);
143 COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol);
144 COFFSection *createSection(StringRef Name);
145
146 template <typename object_t, typename list_t>
147 object_t *createCOFFEntity(StringRef Name, list_t &List);
148
149 void DefineSection(MCSectionData const &SectionData);
150 void DefineSymbol(MCSymbol const &Symbol,
151 MCSymbolData const &SymbolData,
152 MCAssembler &Assembler);
153
154 void MakeSymbolReal(COFFSymbol &S, size_t Index);
155 void MakeSectionReal(COFFSection &S, size_t Number);
156
157 bool ExportSection(COFFSection const *S);
158 bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm);
159
160 bool IsPhysicalSection(COFFSection *S);
161
162 // Entity writing methods.
163
164 void WriteFileHeader(const COFF::header &Header);
165 void WriteSymbol(const COFFSymbol *S);
166 void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
167 void WriteSectionHeader(const COFF::section &S);
168 void WriteRelocation(const COFF::relocation &R);
169
170 // MCObjectWriter interface implementation.
171
172 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout);
173
174 void RecordRelocation(const MCAssembler &Asm,
175 const MCAsmLayout &Layout,
176 const MCFragment *Fragment,
177 const MCFixup &Fixup,
178 MCValue Target,
179 uint64_t &FixedValue);
180
181 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
182 };
183 }
184
write_uint32_le(void * Data,uint32_t const & Value)185 static inline void write_uint32_le(void *Data, uint32_t const &Value) {
186 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
187 Ptr[0] = (Value & 0x000000FF) >> 0;
188 Ptr[1] = (Value & 0x0000FF00) >> 8;
189 Ptr[2] = (Value & 0x00FF0000) >> 16;
190 Ptr[3] = (Value & 0xFF000000) >> 24;
191 }
192
write_uint16_le(void * Data,uint16_t const & Value)193 static inline void write_uint16_le(void *Data, uint16_t const &Value) {
194 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
195 Ptr[0] = (Value & 0x00FF) >> 0;
196 Ptr[1] = (Value & 0xFF00) >> 8;
197 }
198
write_uint8_le(void * Data,uint8_t const & Value)199 static inline void write_uint8_le(void *Data, uint8_t const &Value) {
200 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
201 Ptr[0] = (Value & 0xFF) >> 0;
202 }
203
204 //------------------------------------------------------------------------------
205 // Symbol class implementation
206
COFFSymbol(StringRef name)207 COFFSymbol::COFFSymbol(StringRef name)
208 : Name(name.begin(), name.end())
209 , Other(NULL)
210 , Section(NULL)
211 , Relocations(0)
212 , MCData(NULL) {
213 memset(&Data, 0, sizeof(Data));
214 }
215
size() const216 size_t COFFSymbol::size() const {
217 return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
218 }
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.
set_name_offset(uint32_t Offset)223 void COFFSymbol::set_name_offset(uint32_t Offset) {
224 write_uint32_le(Data.Name + 0, 0);
225 write_uint32_le(Data.Name + 4, Offset);
226 }
227
228 /// logic to decide if the symbol should be reported in the symbol table
should_keep() const229 bool COFFSymbol::should_keep() const {
230 // no section means its external, keep it
231 if (Section == NULL)
232 return true;
233
234 // if it has relocations pointing at it, keep it
235 if (Relocations > 0) {
236 assert(Section->Number != -1 && "Sections with relocations must be real!");
237 return true;
238 }
239
240 // if the section its in is being droped, drop it
241 if (Section->Number == -1)
242 return false;
243
244 // if it is the section symbol, keep it
245 if (Section->Symbol == this)
246 return true;
247
248 // if its temporary, drop it
249 if (MCData && MCData->getSymbol().isTemporary())
250 return false;
251
252 // otherwise, keep it
253 return true;
254 }
255
256 //------------------------------------------------------------------------------
257 // Section class implementation
258
COFFSection(StringRef name)259 COFFSection::COFFSection(StringRef name)
260 : Name(name)
261 , MCData(NULL)
262 , Symbol(NULL) {
263 memset(&Header, 0, sizeof(Header));
264 }
265
size()266 size_t COFFSection::size() {
267 return COFF::SectionSize;
268 }
269
270 //------------------------------------------------------------------------------
271 // StringTable class implementation
272
273 /// Write the length of the string table into Data.
274 /// The length of the string table includes uint32 length header.
update_length()275 void StringTable::update_length() {
276 write_uint32_le(&Data.front(), Data.size());
277 }
278
StringTable()279 StringTable::StringTable() {
280 // The string table data begins with the length of the entire string table
281 // including the length header. Allocate space for this header.
282 Data.resize(4);
283 update_length();
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(StringRef String)292 size_t StringTable::insert(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(MCWinCOFFObjectTargetWriter * MOTW,raw_ostream & OS)316 WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
317 raw_ostream &OS)
318 : MCObjectWriter(OS, true)
319 , TargetObjectWriter(MOTW) {
320 memset(&Header, 0, sizeof(Header));
321
322 Header.Machine = TargetObjectWriter->getMachine();
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(StringRef Name)346 COFFSection *WinCOFFObjectWriter::createSection(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(StringRef Name,list_t & List)353 object_t *WinCOFFObjectWriter::createCOFFEntity(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(MCSymbol const & Symbol,MCSymbolData const & SymbolData,MCAssembler & Assembler)413 void WinCOFFObjectWriter::DefineSymbol(MCSymbol const &Symbol,
414 MCSymbolData const &SymbolData,
415 MCAssembler &Assembler) {
416 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol);
417
418 coff_symbol->Data.Type = (SymbolData.getFlags() & 0x0000FFFF) >> 0;
419 coff_symbol->Data.StorageClass = (SymbolData.getFlags() & 0x00FF0000) >> 16;
420
421 if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
422 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
423
424 if (Symbol.isVariable()) {
425 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
426
427 // FIXME: This assert message isn't very good.
428 assert(Symbol.getVariableValue()->getKind() == MCExpr::SymbolRef &&
429 "Value must be a SymbolRef!");
430
431 coff_symbol->Other = GetOrCreateCOFFSymbol(&Symbol);
432 } else {
433 std::string WeakName = std::string(".weak.")
434 + Symbol.getName().str()
435 + ".default";
436 COFFSymbol *WeakDefault = createSymbol(WeakName);
437 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
438 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
439 WeakDefault->Data.Type = 0;
440 WeakDefault->Data.Value = 0;
441 coff_symbol->Other = WeakDefault;
442 }
443
444 // Setup the Weak External auxiliary symbol.
445 coff_symbol->Aux.resize(1);
446 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
447 coff_symbol->Aux[0].AuxType = ATWeakExternal;
448 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
449 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
450 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
451 }
452
453 // If no storage class was specified in the streamer, define it here.
454 if (coff_symbol->Data.StorageClass == 0) {
455 bool external = SymbolData.isExternal() || (SymbolData.Fragment == NULL);
456
457 coff_symbol->Data.StorageClass =
458 external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC;
459 }
460
461 if (SymbolData.Fragment != NULL)
462 coff_symbol->Section =
463 SectionMap[&SymbolData.Fragment->getParent()->getSection()];
464
465 // Bind internal COFF symbol to MC symbol.
466 coff_symbol->MCData = &SymbolData;
467 SymbolMap[&Symbol] = coff_symbol;
468 }
469
470 /// making a section real involves assigned it a number and putting
471 /// name into the string table if needed
MakeSectionReal(COFFSection & S,size_t Number)472 void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
473 if (S.Name.size() > COFF::NameSize) {
474 size_t StringTableEntry = Strings.insert(S.Name.c_str());
475
476 // FIXME: Why is this number 999999? This number is never mentioned in the
477 // spec. I'm assuming this is due to the printed value needing to fit into
478 // the S.Header.Name field. In which case why not 9999999 (7 9's instead of
479 // 6)? The spec does not state if this entry should be null terminated in
480 // this case, and thus this seems to be the best way to do it. I think I
481 // just solved my own FIXME...
482 if (StringTableEntry > 999999)
483 report_fatal_error("COFF string table is greater than 999999 bytes.");
484
485 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
486 } else
487 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
488
489 S.Number = Number;
490 S.Symbol->Data.SectionNumber = S.Number;
491 S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
492 }
493
MakeSymbolReal(COFFSymbol & S,size_t Index)494 void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
495 if (S.Name.size() > COFF::NameSize) {
496 size_t StringTableEntry = Strings.insert(S.Name.c_str());
497
498 S.set_name_offset(StringTableEntry);
499 } else
500 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
501 S.Index = Index;
502 }
503
ExportSection(COFFSection const * S)504 bool WinCOFFObjectWriter::ExportSection(COFFSection const *S) {
505 return !S->MCData->getFragmentList().empty();
506 }
507
ExportSymbol(MCSymbolData const & SymbolData,MCAssembler & Asm)508 bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
509 MCAssembler &Asm) {
510 // This doesn't seem to be right. Strings referred to from the .data section
511 // need symbols so they can be linked to code in the .text section right?
512
513 // return Asm.isSymbolLinkerVisible (&SymbolData);
514
515 // For now, all non-variable symbols are exported,
516 // the linker will sort the rest out for us.
517 return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable();
518 }
519
IsPhysicalSection(COFFSection * S)520 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
521 return (S->Header.Characteristics
522 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
523 }
524
525 //------------------------------------------------------------------------------
526 // entity writing methods
527
WriteFileHeader(const COFF::header & Header)528 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
529 WriteLE16(Header.Machine);
530 WriteLE16(Header.NumberOfSections);
531 WriteLE32(Header.TimeDateStamp);
532 WriteLE32(Header.PointerToSymbolTable);
533 WriteLE32(Header.NumberOfSymbols);
534 WriteLE16(Header.SizeOfOptionalHeader);
535 WriteLE16(Header.Characteristics);
536 }
537
WriteSymbol(const COFFSymbol * S)538 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
539 WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
540 WriteLE32(S->Data.Value);
541 WriteLE16(S->Data.SectionNumber);
542 WriteLE16(S->Data.Type);
543 Write8(S->Data.StorageClass);
544 Write8(S->Data.NumberOfAuxSymbols);
545 WriteAuxiliarySymbols(S->Aux);
546 }
547
WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols & S)548 void WinCOFFObjectWriter::WriteAuxiliarySymbols(
549 const COFFSymbol::AuxiliarySymbols &S) {
550 for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
551 i != e; ++i) {
552 switch(i->AuxType) {
553 case ATFunctionDefinition:
554 WriteLE32(i->Aux.FunctionDefinition.TagIndex);
555 WriteLE32(i->Aux.FunctionDefinition.TotalSize);
556 WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
557 WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
558 WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
559 break;
560 case ATbfAndefSymbol:
561 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
562 WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
563 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
564 WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
565 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
566 break;
567 case ATWeakExternal:
568 WriteLE32(i->Aux.WeakExternal.TagIndex);
569 WriteLE32(i->Aux.WeakExternal.Characteristics);
570 WriteZeros(sizeof(i->Aux.WeakExternal.unused));
571 break;
572 case ATFile:
573 WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
574 sizeof(i->Aux.File.FileName)));
575 break;
576 case ATSectionDefinition:
577 WriteLE32(i->Aux.SectionDefinition.Length);
578 WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
579 WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
580 WriteLE32(i->Aux.SectionDefinition.CheckSum);
581 WriteLE16(i->Aux.SectionDefinition.Number);
582 Write8(i->Aux.SectionDefinition.Selection);
583 WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
584 break;
585 }
586 }
587 }
588
WriteSectionHeader(const COFF::section & S)589 void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
590 WriteBytes(StringRef(S.Name, COFF::NameSize));
591
592 WriteLE32(S.VirtualSize);
593 WriteLE32(S.VirtualAddress);
594 WriteLE32(S.SizeOfRawData);
595 WriteLE32(S.PointerToRawData);
596 WriteLE32(S.PointerToRelocations);
597 WriteLE32(S.PointerToLineNumbers);
598 WriteLE16(S.NumberOfRelocations);
599 WriteLE16(S.NumberOfLineNumbers);
600 WriteLE32(S.Characteristics);
601 }
602
WriteRelocation(const COFF::relocation & R)603 void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
604 WriteLE32(R.VirtualAddress);
605 WriteLE32(R.SymbolTableIndex);
606 WriteLE16(R.Type);
607 }
608
609 ////////////////////////////////////////////////////////////////////////////////
610 // MCObjectWriter interface implementations
611
ExecutePostLayoutBinding(MCAssembler & Asm,const MCAsmLayout & Layout)612 void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
613 const MCAsmLayout &Layout) {
614 // "Define" each section & symbol. This creates section & symbol
615 // entries in the staging area.
616
617 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
618 DefineSection(*i);
619
620 for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
621 e = Asm.symbol_end(); i != e; i++) {
622 if (ExportSymbol(*i, Asm)) {
623 const MCSymbol &Alias = i->getSymbol();
624 const MCSymbol &Symbol = Alias.AliasedSymbol();
625 DefineSymbol(Alias, Asm.getSymbolData(Symbol), Asm);
626 }
627 }
628 }
629
RecordRelocation(const MCAssembler & Asm,const MCAsmLayout & Layout,const MCFragment * Fragment,const MCFixup & Fixup,MCValue Target,uint64_t & FixedValue)630 void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
631 const MCAsmLayout &Layout,
632 const MCFragment *Fragment,
633 const MCFixup &Fixup,
634 MCValue Target,
635 uint64_t &FixedValue) {
636 assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
637
638 const MCSymbol *A = &Target.getSymA()->getSymbol();
639 MCSymbolData &A_SD = Asm.getSymbolData(*A);
640
641 MCSectionData const *SectionData = Fragment->getParent();
642
643 // Mark this symbol as requiring an entry in the symbol table.
644 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
645 "Section must already have been defined in ExecutePostLayoutBinding!");
646 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
647 "Symbol must already have been defined in ExecutePostLayoutBinding!");
648
649 COFFSection *coff_section = SectionMap[&SectionData->getSection()];
650 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
651 const MCSymbolRefExpr *SymA = Target.getSymA();
652 const MCSymbolRefExpr *SymB = Target.getSymB();
653 const bool CrossSection = SymB &&
654 &SymA->getSymbol().getSection() != &SymB->getSymbol().getSection();
655
656 if (Target.getSymB()) {
657 const MCSymbol *B = &Target.getSymB()->getSymbol();
658 MCSymbolData &B_SD = Asm.getSymbolData(*B);
659
660 // Offset of the symbol in the section
661 int64_t a = Layout.getSymbolOffset(&B_SD);
662
663 // Ofeset of the relocation in the section
664 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
665
666 FixedValue = b - a;
667 // In the case where we have SymbA and SymB, we just need to store the delta
668 // between the two symbols. Update FixedValue to account for the delta, and
669 // skip recording the relocation.
670 if (!CrossSection)
671 return;
672 } else {
673 FixedValue = Target.getConstant();
674 }
675
676 COFFRelocation Reloc;
677
678 Reloc.Data.SymbolTableIndex = 0;
679 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
680
681 // Turn relocations for temporary symbols into section relocations.
682 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
683 Reloc.Symb = coff_symbol->Section->Symbol;
684 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
685 + coff_symbol->MCData->getOffset();
686 } else
687 Reloc.Symb = coff_symbol;
688
689 ++Reloc.Symb->Relocations;
690
691 Reloc.Data.VirtualAddress += Fixup.getOffset();
692
693 unsigned FixupKind = Fixup.getKind();
694
695 if (CrossSection)
696 FixupKind = FK_PCRel_4;
697
698 Reloc.Data.Type = TargetObjectWriter->getRelocType(FixupKind);
699
700 // FIXME: Can anyone explain what this does other than adjust for the size
701 // of the offset?
702 if (Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32 ||
703 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32)
704 FixedValue += 4;
705
706 coff_section->Relocations.push_back(Reloc);
707 }
708
WriteObject(MCAssembler & Asm,const MCAsmLayout & Layout)709 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
710 const MCAsmLayout &Layout) {
711 // Assign symbol and section indexes and offsets.
712 Header.NumberOfSections = 0;
713
714 for (sections::iterator i = Sections.begin(),
715 e = Sections.end(); i != e; i++) {
716 if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
717 MakeSectionReal(**i, ++Header.NumberOfSections);
718 } else {
719 (*i)->Number = -1;
720 }
721 }
722
723 Header.NumberOfSymbols = 0;
724
725 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
726 COFFSymbol *coff_symbol = *i;
727 MCSymbolData const *SymbolData = coff_symbol->MCData;
728
729 // Update section number & offset for symbols that have them.
730 if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
731 assert(coff_symbol->Section != NULL);
732
733 coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
734 coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
735 + SymbolData->Offset;
736 }
737
738 if (coff_symbol->should_keep()) {
739 MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
740
741 // Update auxiliary symbol info.
742 coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
743 Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
744 } else
745 coff_symbol->Index = -1;
746 }
747
748 // Fixup weak external references.
749 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
750 COFFSymbol *coff_symbol = *i;
751 if (coff_symbol->Other != NULL) {
752 assert(coff_symbol->Index != -1);
753 assert(coff_symbol->Aux.size() == 1 &&
754 "Symbol must contain one aux symbol!");
755 assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
756 "Symbol's aux symbol must be a Weak External!");
757 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
758 }
759 }
760
761 // Assign file offsets to COFF object file structures.
762
763 unsigned offset = 0;
764
765 offset += COFF::HeaderSize;
766 offset += COFF::SectionSize * Header.NumberOfSections;
767
768 for (MCAssembler::const_iterator i = Asm.begin(),
769 e = Asm.end();
770 i != e; i++) {
771 COFFSection *Sec = SectionMap[&i->getSection()];
772
773 if (Sec->Number == -1)
774 continue;
775
776 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);
777
778 if (IsPhysicalSection(Sec)) {
779 Sec->Header.PointerToRawData = offset;
780
781 offset += Sec->Header.SizeOfRawData;
782 }
783
784 if (Sec->Relocations.size() > 0) {
785 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
786
787 if (RelocationsOverflow) {
788 // Signal overflow by setting NumberOfSections to max value. Actual
789 // size is found in reloc #0. Microsoft tools understand this.
790 Sec->Header.NumberOfRelocations = 0xffff;
791 } else {
792 Sec->Header.NumberOfRelocations = Sec->Relocations.size();
793 }
794 Sec->Header.PointerToRelocations = offset;
795
796 if (RelocationsOverflow) {
797 // Reloc #0 will contain actual count, so make room for it.
798 offset += COFF::RelocationSize;
799 }
800
801 offset += COFF::RelocationSize * Sec->Relocations.size();
802
803 for (relocations::iterator cr = Sec->Relocations.begin(),
804 er = Sec->Relocations.end();
805 cr != er; ++cr) {
806 assert((*cr).Symb->Index != -1);
807 (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
808 }
809 }
810
811 assert(Sec->Symbol->Aux.size() == 1
812 && "Section's symbol must have one aux!");
813 AuxSymbol &Aux = Sec->Symbol->Aux[0];
814 assert(Aux.AuxType == ATSectionDefinition &&
815 "Section's symbol's aux symbol must be a Section Definition!");
816 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
817 Aux.Aux.SectionDefinition.NumberOfRelocations =
818 Sec->Header.NumberOfRelocations;
819 Aux.Aux.SectionDefinition.NumberOfLinenumbers =
820 Sec->Header.NumberOfLineNumbers;
821 }
822
823 Header.PointerToSymbolTable = offset;
824
825 Header.TimeDateStamp = sys::TimeValue::now().toEpochTime();
826
827 // Write it all to disk...
828 WriteFileHeader(Header);
829
830 {
831 sections::iterator i, ie;
832 MCAssembler::const_iterator j, je;
833
834 for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
835 if ((*i)->Number != -1) {
836 if ((*i)->Relocations.size() >= 0xffff) {
837 (*i)->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
838 }
839 WriteSectionHeader((*i)->Header);
840 }
841
842 for (i = Sections.begin(), ie = Sections.end(),
843 j = Asm.begin(), je = Asm.end();
844 (i != ie) && (j != je); ++i, ++j) {
845
846 if ((*i)->Number == -1)
847 continue;
848
849 if ((*i)->Header.PointerToRawData != 0) {
850 assert(OS.tell() == (*i)->Header.PointerToRawData &&
851 "Section::PointerToRawData is insane!");
852
853 Asm.writeSectionData(j, Layout);
854 }
855
856 if ((*i)->Relocations.size() > 0) {
857 assert(OS.tell() == (*i)->Header.PointerToRelocations &&
858 "Section::PointerToRelocations is insane!");
859
860 if ((*i)->Relocations.size() >= 0xffff) {
861 // In case of overflow, write actual relocation count as first
862 // relocation. Including the synthetic reloc itself (+ 1).
863 COFF::relocation r;
864 r.VirtualAddress = (*i)->Relocations.size() + 1;
865 r.SymbolTableIndex = 0;
866 r.Type = 0;
867 WriteRelocation(r);
868 }
869
870 for (relocations::const_iterator k = (*i)->Relocations.begin(),
871 ke = (*i)->Relocations.end();
872 k != ke; k++) {
873 WriteRelocation(k->Data);
874 }
875 } else
876 assert((*i)->Header.PointerToRelocations == 0 &&
877 "Section::PointerToRelocations is insane!");
878 }
879 }
880
881 assert(OS.tell() == Header.PointerToSymbolTable &&
882 "Header::PointerToSymbolTable is insane!");
883
884 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
885 if ((*i)->Index != -1)
886 WriteSymbol(*i);
887
888 OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
889 }
890
MCWinCOFFObjectTargetWriter(unsigned Machine_)891 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :
892 Machine(Machine_) {
893 }
894
895 //------------------------------------------------------------------------------
896 // WinCOFFObjectWriter factory function
897
898 namespace llvm {
createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter * MOTW,raw_ostream & OS)899 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
900 raw_ostream &OS) {
901 return new WinCOFFObjectWriter(MOTW, OS);
902 }
903 }
904