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 84 COFFRelocation() : Symb(NULL) {} 85 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 } 184 185 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 } 192 193 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 } 198 199 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 206 207 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 } 215 216 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. 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 229 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 258 259 COFFSection::COFFSection(StringRef name) 260 : Name(name) 261 , MCData(NULL) 262 , Symbol(NULL) { 263 memset(&Header, 0, sizeof(Header)); 264 } 265 266 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. 275 void StringTable::update_length() { 276 write_uint32_le(&Data.front(), Data.size()); 277 } 278 279 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 } 285 286 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. 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 315 316 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 } 324 325 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 } 331 332 COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) { 333 return createCOFFEntity<COFFSymbol>(Name, Symbols); 334 } 335 336 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 } 345 346 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> 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. 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. 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 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 } 493 494 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 } 503 504 bool WinCOFFObjectWriter::ExportSection(COFFSection const *S) { 505 return !S->MCData->getFragmentList().empty(); 506 } 507 508 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 } 519 520 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 527 528 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 } 537 538 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 } 547 548 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 } 588 589 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 } 602 603 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 611 612 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 } 629 630 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 } 708 709 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 } 890 891 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) : 892 Machine(Machine_) { 893 } 894 895 //------------------------------------------------------------------------------ 896 // WinCOFFObjectWriter factory function 897 898 namespace llvm { 899 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, 900 raw_ostream &OS) { 901 return new WinCOFFObjectWriter(MOTW, OS); 902 } 903 } 904
