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 88 COFFRelocation() : Symb(NULL) {} 89 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 } 185 186 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 } 193 194 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 } 199 200 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 207 208 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 } 216 217 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. 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 230 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 259 260 COFFSection::COFFSection(llvm::StringRef name) 261 : Name(name) 262 , MCData(NULL) 263 , Symbol(NULL) { 264 memset(&Header, 0, sizeof(Header)); 265 } 266 267 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. 276 void StringTable::update_length() { 277 write_uint32_le(&Data.front(), Data.size()); 278 } 279 280 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 } 285 286 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(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 315 316 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 } 324 325 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(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> 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. 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(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 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 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry)); 488 } else 489 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size()); 490 491 S.Number = Number; 492 S.Symbol->Data.SectionNumber = S.Number; 493 S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number; 494 } 495 496 void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) { 497 if (S.Name.size() > COFF::NameSize) { 498 size_t StringTableEntry = Strings.insert(S.Name.c_str()); 499 500 S.set_name_offset(StringTableEntry); 501 } else 502 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size()); 503 S.Index = Index; 504 } 505 506 bool WinCOFFObjectWriter::ExportSection(COFFSection const *S) { 507 return !S->MCData->getFragmentList().empty(); 508 } 509 510 bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData, 511 MCAssembler &Asm) { 512 // This doesn't seem to be right. Strings referred to from the .data section 513 // need symbols so they can be linked to code in the .text section right? 514 515 // return Asm.isSymbolLinkerVisible (&SymbolData); 516 517 // For now, all non-variable symbols are exported, 518 // the linker will sort the rest out for us. 519 return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable(); 520 } 521 522 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) { 523 return (S->Header.Characteristics 524 & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0; 525 } 526 527 //------------------------------------------------------------------------------ 528 // entity writing methods 529 530 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) { 531 WriteLE16(Header.Machine); 532 WriteLE16(Header.NumberOfSections); 533 WriteLE32(Header.TimeDateStamp); 534 WriteLE32(Header.PointerToSymbolTable); 535 WriteLE32(Header.NumberOfSymbols); 536 WriteLE16(Header.SizeOfOptionalHeader); 537 WriteLE16(Header.Characteristics); 538 } 539 540 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) { 541 WriteBytes(StringRef(S->Data.Name, COFF::NameSize)); 542 WriteLE32(S->Data.Value); 543 WriteLE16(S->Data.SectionNumber); 544 WriteLE16(S->Data.Type); 545 Write8(S->Data.StorageClass); 546 Write8(S->Data.NumberOfAuxSymbols); 547 WriteAuxiliarySymbols(S->Aux); 548 } 549 550 void WinCOFFObjectWriter::WriteAuxiliarySymbols( 551 const COFFSymbol::AuxiliarySymbols &S) { 552 for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end(); 553 i != e; ++i) { 554 switch(i->AuxType) { 555 case ATFunctionDefinition: 556 WriteLE32(i->Aux.FunctionDefinition.TagIndex); 557 WriteLE32(i->Aux.FunctionDefinition.TotalSize); 558 WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber); 559 WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction); 560 WriteZeros(sizeof(i->Aux.FunctionDefinition.unused)); 561 break; 562 case ATbfAndefSymbol: 563 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1)); 564 WriteLE16(i->Aux.bfAndefSymbol.Linenumber); 565 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2)); 566 WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction); 567 WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3)); 568 break; 569 case ATWeakExternal: 570 WriteLE32(i->Aux.WeakExternal.TagIndex); 571 WriteLE32(i->Aux.WeakExternal.Characteristics); 572 WriteZeros(sizeof(i->Aux.WeakExternal.unused)); 573 break; 574 case ATFile: 575 WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName), 576 sizeof(i->Aux.File.FileName))); 577 break; 578 case ATSectionDefinition: 579 WriteLE32(i->Aux.SectionDefinition.Length); 580 WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations); 581 WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers); 582 WriteLE32(i->Aux.SectionDefinition.CheckSum); 583 WriteLE16(i->Aux.SectionDefinition.Number); 584 Write8(i->Aux.SectionDefinition.Selection); 585 WriteZeros(sizeof(i->Aux.SectionDefinition.unused)); 586 break; 587 } 588 } 589 } 590 591 void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) { 592 WriteBytes(StringRef(S.Name, COFF::NameSize)); 593 594 WriteLE32(S.VirtualSize); 595 WriteLE32(S.VirtualAddress); 596 WriteLE32(S.SizeOfRawData); 597 WriteLE32(S.PointerToRawData); 598 WriteLE32(S.PointerToRelocations); 599 WriteLE32(S.PointerToLineNumbers); 600 WriteLE16(S.NumberOfRelocations); 601 WriteLE16(S.NumberOfLineNumbers); 602 WriteLE32(S.Characteristics); 603 } 604 605 void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) { 606 WriteLE32(R.VirtualAddress); 607 WriteLE32(R.SymbolTableIndex); 608 WriteLE16(R.Type); 609 } 610 611 //////////////////////////////////////////////////////////////////////////////// 612 // MCObjectWriter interface implementations 613 614 void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm, 615 const MCAsmLayout &Layout) { 616 // "Define" each section & symbol. This creates section & symbol 617 // entries in the staging area. 618 619 for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++) 620 DefineSection(*i); 621 622 for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(), 623 e = Asm.symbol_end(); i != e; i++) { 624 if (ExportSymbol(*i, Asm)) 625 DefineSymbol(*i, Asm); 626 } 627 } 628 629 void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm, 630 const MCAsmLayout &Layout, 631 const MCFragment *Fragment, 632 const MCFixup &Fixup, 633 MCValue Target, 634 uint64_t &FixedValue) { 635 assert(Target.getSymA() != NULL && "Relocation must reference a symbol!"); 636 637 const MCSymbol *A = &Target.getSymA()->getSymbol(); 638 MCSymbolData &A_SD = Asm.getSymbolData(*A); 639 640 MCSectionData const *SectionData = Fragment->getParent(); 641 642 // Mark this symbol as requiring an entry in the symbol table. 643 assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() && 644 "Section must already have been defined in ExecutePostLayoutBinding!"); 645 assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() && 646 "Symbol must already have been defined in ExecutePostLayoutBinding!"); 647 648 COFFSection *coff_section = SectionMap[&SectionData->getSection()]; 649 COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()]; 650 const MCSymbolRefExpr *SymA = Target.getSymA(); 651 const MCSymbolRefExpr *SymB = Target.getSymB(); 652 const bool CrossSection = SymB && 653 &SymA->getSymbol().getSection() != &SymB->getSymbol().getSection(); 654 655 if (Target.getSymB()) { 656 const MCSymbol *B = &Target.getSymB()->getSymbol(); 657 MCSymbolData &B_SD = Asm.getSymbolData(*B); 658 659 // Offset of the symbol in the section 660 int64_t a = Layout.getSymbolOffset(&B_SD); 661 662 // Ofeset of the relocation in the section 663 int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); 664 665 FixedValue = b - a; 666 // In the case where we have SymbA and SymB, we just need to store the delta 667 // between the two symbols. Update FixedValue to account for the delta, and 668 // skip recording the relocation. 669 if (!CrossSection) 670 return; 671 } else { 672 FixedValue = Target.getConstant(); 673 } 674 675 COFFRelocation Reloc; 676 677 Reloc.Data.SymbolTableIndex = 0; 678 Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment); 679 680 // Turn relocations for temporary symbols into section relocations. 681 if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) { 682 Reloc.Symb = coff_symbol->Section->Symbol; 683 FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment) 684 + coff_symbol->MCData->getOffset(); 685 } else 686 Reloc.Symb = coff_symbol; 687 688 ++Reloc.Symb->Relocations; 689 690 Reloc.Data.VirtualAddress += Fixup.getOffset(); 691 692 unsigned FixupKind = Fixup.getKind(); 693 694 if (CrossSection) 695 FixupKind = FK_PCRel_4; 696 697 switch (FixupKind) { 698 case FK_PCRel_4: 699 case X86::reloc_riprel_4byte: 700 case X86::reloc_riprel_4byte_movq_load: 701 Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_REL32 702 : COFF::IMAGE_REL_I386_REL32; 703 // FIXME: Can anyone explain what this does other than adjust for the size 704 // of the offset? 705 FixedValue += 4; 706 break; 707 case FK_Data_4: 708 case X86::reloc_signed_4byte: 709 Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_ADDR32 710 : COFF::IMAGE_REL_I386_DIR32; 711 break; 712 case FK_Data_8: 713 if (Is64Bit) 714 Reloc.Data.Type = COFF::IMAGE_REL_AMD64_ADDR64; 715 else 716 llvm_unreachable("unsupported relocation type"); 717 break; 718 default: 719 llvm_unreachable("unsupported relocation type"); 720 } 721 722 coff_section->Relocations.push_back(Reloc); 723 } 724 725 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm, 726 const MCAsmLayout &Layout) { 727 // Assign symbol and section indexes and offsets. 728 Header.NumberOfSections = 0; 729 730 for (sections::iterator i = Sections.begin(), 731 e = Sections.end(); i != e; i++) { 732 if (Layout.getSectionAddressSize((*i)->MCData) > 0) { 733 MakeSectionReal(**i, ++Header.NumberOfSections); 734 } else { 735 (*i)->Number = -1; 736 } 737 } 738 739 Header.NumberOfSymbols = 0; 740 741 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) { 742 COFFSymbol *coff_symbol = *i; 743 MCSymbolData const *SymbolData = coff_symbol->MCData; 744 745 // Update section number & offset for symbols that have them. 746 if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) { 747 assert(coff_symbol->Section != NULL); 748 749 coff_symbol->Data.SectionNumber = coff_symbol->Section->Number; 750 coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment) 751 + SymbolData->Offset; 752 } 753 754 if (coff_symbol->should_keep()) { 755 MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++); 756 757 // Update auxiliary symbol info. 758 coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size(); 759 Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols; 760 } else 761 coff_symbol->Index = -1; 762 } 763 764 // Fixup weak external references. 765 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) { 766 COFFSymbol *coff_symbol = *i; 767 if (coff_symbol->Other != NULL) { 768 assert(coff_symbol->Index != -1); 769 assert(coff_symbol->Aux.size() == 1 && 770 "Symbol must contain one aux symbol!"); 771 assert(coff_symbol->Aux[0].AuxType == ATWeakExternal && 772 "Symbol's aux symbol must be a Weak External!"); 773 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index; 774 } 775 } 776 777 // Assign file offsets to COFF object file structures. 778 779 unsigned offset = 0; 780 781 offset += COFF::HeaderSize; 782 offset += COFF::SectionSize * Header.NumberOfSections; 783 784 for (MCAssembler::const_iterator i = Asm.begin(), 785 e = Asm.end(); 786 i != e; i++) { 787 COFFSection *Sec = SectionMap[&i->getSection()]; 788 789 if (Sec->Number == -1) 790 continue; 791 792 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i); 793 794 if (IsPhysicalSection(Sec)) { 795 Sec->Header.PointerToRawData = offset; 796 797 offset += Sec->Header.SizeOfRawData; 798 } 799 800 if (Sec->Relocations.size() > 0) { 801 Sec->Header.NumberOfRelocations = Sec->Relocations.size(); 802 Sec->Header.PointerToRelocations = offset; 803 804 offset += COFF::RelocationSize * Sec->Relocations.size(); 805 806 for (relocations::iterator cr = Sec->Relocations.begin(), 807 er = Sec->Relocations.end(); 808 cr != er; ++cr) { 809 assert((*cr).Symb->Index != -1); 810 (*cr).Data.SymbolTableIndex = (*cr).Symb->Index; 811 } 812 } 813 814 assert(Sec->Symbol->Aux.size() == 1 815 && "Section's symbol must have one aux!"); 816 AuxSymbol &Aux = Sec->Symbol->Aux[0]; 817 assert(Aux.AuxType == ATSectionDefinition && 818 "Section's symbol's aux symbol must be a Section Definition!"); 819 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData; 820 Aux.Aux.SectionDefinition.NumberOfRelocations = 821 Sec->Header.NumberOfRelocations; 822 Aux.Aux.SectionDefinition.NumberOfLinenumbers = 823 Sec->Header.NumberOfLineNumbers; 824 } 825 826 Header.PointerToSymbolTable = offset; 827 828 Header.TimeDateStamp = sys::TimeValue::now().toEpochTime(); 829 830 // Write it all to disk... 831 WriteFileHeader(Header); 832 833 { 834 sections::iterator i, ie; 835 MCAssembler::const_iterator j, je; 836 837 for (i = Sections.begin(), ie = Sections.end(); i != ie; i++) 838 if ((*i)->Number != -1) 839 WriteSectionHeader((*i)->Header); 840 841 for (i = Sections.begin(), ie = Sections.end(), 842 j = Asm.begin(), je = Asm.end(); 843 (i != ie) && (j != je); ++i, ++j) { 844 845 if ((*i)->Number == -1) 846 continue; 847 848 if ((*i)->Header.PointerToRawData != 0) { 849 assert(OS.tell() == (*i)->Header.PointerToRawData && 850 "Section::PointerToRawData is insane!"); 851 852 Asm.WriteSectionData(j, Layout); 853 } 854 855 if ((*i)->Relocations.size() > 0) { 856 assert(OS.tell() == (*i)->Header.PointerToRelocations && 857 "Section::PointerToRelocations is insane!"); 858 859 for (relocations::const_iterator k = (*i)->Relocations.begin(), 860 ke = (*i)->Relocations.end(); 861 k != ke; k++) { 862 WriteRelocation(k->Data); 863 } 864 } else 865 assert((*i)->Header.PointerToRelocations == 0 && 866 "Section::PointerToRelocations is insane!"); 867 } 868 } 869 870 assert(OS.tell() == Header.PointerToSymbolTable && 871 "Header::PointerToSymbolTable is insane!"); 872 873 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) 874 if ((*i)->Index != -1) 875 WriteSymbol(*i); 876 877 OS.write((char const *)&Strings.Data.front(), Strings.Data.size()); 878 } 879 880 //------------------------------------------------------------------------------ 881 // WinCOFFObjectWriter factory function 882 883 namespace llvm { 884 MCObjectWriter *createWinCOFFObjectWriter(raw_ostream &OS, bool is64Bit) { 885 return new WinCOFFObjectWriter(OS, is64Bit); 886 } 887 } 888
