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/ADT/Twine.h" 22#include "llvm/MC/MCAsmLayout.h" 23#include "llvm/MC/MCAssembler.h" 24#include "llvm/MC/MCContext.h" 25#include "llvm/MC/MCExpr.h" 26#include "llvm/MC/MCObjectWriter.h" 27#include "llvm/MC/MCSection.h" 28#include "llvm/MC/MCSectionCOFF.h" 29#include "llvm/MC/MCSymbol.h" 30#include "llvm/MC/MCValue.h" 31#include "llvm/Support/COFF.h" 32#include "llvm/Support/Debug.h" 33#include "llvm/Support/ErrorHandling.h" 34#include "llvm/Support/TimeValue.h" 35#include <cstdio> 36 37using namespace llvm; 38 39namespace { 40typedef SmallString<COFF::NameSize> name; 41 42enum AuxiliaryType { 43 ATFunctionDefinition, 44 ATbfAndefSymbol, 45 ATWeakExternal, 46 ATFile, 47 ATSectionDefinition 48}; 49 50struct AuxSymbol { 51 AuxiliaryType AuxType; 52 COFF::Auxiliary Aux; 53}; 54 55class COFFSymbol; 56class COFFSection; 57 58class COFFSymbol { 59public: 60 COFF::symbol Data; 61 62 typedef SmallVector<AuxSymbol, 1> AuxiliarySymbols; 63 64 name Name; 65 int Index; 66 AuxiliarySymbols Aux; 67 COFFSymbol *Other; 68 COFFSection *Section; 69 int Relocations; 70 71 MCSymbolData const *MCData; 72 73 COFFSymbol(StringRef name); 74 size_t size() const; 75 void set_name_offset(uint32_t Offset); 76 77 bool should_keep() const; 78}; 79 80// This class contains staging data for a COFF relocation entry. 81struct COFFRelocation { 82 COFF::relocation Data; 83 COFFSymbol *Symb; 84 85 COFFRelocation() : Symb(NULL) {} 86 static size_t size() { return COFF::RelocationSize; } 87}; 88 89typedef std::vector<COFFRelocation> relocations; 90 91class COFFSection { 92public: 93 COFF::section Header; 94 95 std::string Name; 96 int Number; 97 MCSectionData const *MCData; 98 COFFSymbol *Symbol; 99 relocations Relocations; 100 101 COFFSection(StringRef name); 102 static size_t size(); 103}; 104 105// This class holds the COFF string table. 106class StringTable { 107 typedef StringMap<size_t> map; 108 map Map; 109 110 void update_length(); 111public: 112 std::vector<char> Data; 113 114 StringTable(); 115 size_t size() const; 116 size_t insert(StringRef String); 117}; 118 119class WinCOFFObjectWriter : public MCObjectWriter { 120public: 121 122 typedef std::vector<COFFSymbol*> symbols; 123 typedef std::vector<COFFSection*> sections; 124 125 typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map; 126 typedef DenseMap<MCSection const *, COFFSection *> section_map; 127 128 llvm::OwningPtr<MCWinCOFFObjectTargetWriter> TargetObjectWriter; 129 130 // Root level file contents. 131 COFF::header Header; 132 sections Sections; 133 symbols Symbols; 134 StringTable Strings; 135 136 // Maps used during object file creation. 137 section_map SectionMap; 138 symbol_map SymbolMap; 139 140 WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, raw_ostream &OS); 141 virtual ~WinCOFFObjectWriter(); 142 143 COFFSymbol *createSymbol(StringRef Name); 144 COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol); 145 COFFSection *createSection(StringRef Name); 146 147 template <typename object_t, typename list_t> 148 object_t *createCOFFEntity(StringRef Name, list_t &List); 149 150 void DefineSection(MCSectionData const &SectionData); 151 void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler, 152 const MCAsmLayout &Layout); 153 154 void MakeSymbolReal(COFFSymbol &S, size_t Index); 155 void MakeSectionReal(COFFSection &S, size_t Number); 156 157 bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm); 158 159 bool IsPhysicalSection(COFFSection *S); 160 161 // Entity writing methods. 162 163 void WriteFileHeader(const COFF::header &Header); 164 void WriteSymbol(const COFFSymbol *S); 165 void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S); 166 void WriteSectionHeader(const COFF::section &S); 167 void WriteRelocation(const COFF::relocation &R); 168 169 // MCObjectWriter interface implementation. 170 171 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout); 172 173 void RecordRelocation(const MCAssembler &Asm, 174 const MCAsmLayout &Layout, 175 const MCFragment *Fragment, 176 const MCFixup &Fixup, 177 MCValue Target, 178 uint64_t &FixedValue); 179 180 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout); 181}; 182} 183 184static inline void write_uint32_le(void *Data, uint32_t const &Value) { 185 uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data); 186 Ptr[0] = (Value & 0x000000FF) >> 0; 187 Ptr[1] = (Value & 0x0000FF00) >> 8; 188 Ptr[2] = (Value & 0x00FF0000) >> 16; 189 Ptr[3] = (Value & 0xFF000000) >> 24; 190} 191 192//------------------------------------------------------------------------------ 193// Symbol class implementation 194 195COFFSymbol::COFFSymbol(StringRef name) 196 : Name(name.begin(), name.end()) 197 , Other(NULL) 198 , Section(NULL) 199 , Relocations(0) 200 , MCData(NULL) { 201 memset(&Data, 0, sizeof(Data)); 202} 203 204size_t COFFSymbol::size() const { 205 return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize); 206} 207 208// In the case that the name does not fit within 8 bytes, the offset 209// into the string table is stored in the last 4 bytes instead, leaving 210// the first 4 bytes as 0. 211void COFFSymbol::set_name_offset(uint32_t Offset) { 212 write_uint32_le(Data.Name + 0, 0); 213 write_uint32_le(Data.Name + 4, Offset); 214} 215 216/// logic to decide if the symbol should be reported in the symbol table 217bool COFFSymbol::should_keep() const { 218 // no section means its external, keep it 219 if (Section == NULL) 220 return true; 221 222 // if it has relocations pointing at it, keep it 223 if (Relocations > 0) { 224 assert(Section->Number != -1 && "Sections with relocations must be real!"); 225 return true; 226 } 227 228 // if the section its in is being droped, drop it 229 if (Section->Number == -1) 230 return false; 231 232 // if it is the section symbol, keep it 233 if (Section->Symbol == this) 234 return true; 235 236 // if its temporary, drop it 237 if (MCData && MCData->getSymbol().isTemporary()) 238 return false; 239 240 // otherwise, keep it 241 return true; 242} 243 244//------------------------------------------------------------------------------ 245// Section class implementation 246 247COFFSection::COFFSection(StringRef name) 248 : Name(name) 249 , MCData(NULL) 250 , Symbol(NULL) { 251 memset(&Header, 0, sizeof(Header)); 252} 253 254size_t COFFSection::size() { 255 return COFF::SectionSize; 256} 257 258//------------------------------------------------------------------------------ 259// StringTable class implementation 260 261/// Write the length of the string table into Data. 262/// The length of the string table includes uint32 length header. 263void StringTable::update_length() { 264 write_uint32_le(&Data.front(), Data.size()); 265} 266 267StringTable::StringTable() { 268 // The string table data begins with the length of the entire string table 269 // including the length header. Allocate space for this header. 270 Data.resize(4); 271 update_length(); 272} 273 274size_t StringTable::size() const { 275 return Data.size(); 276} 277 278/// Add String to the table iff it is not already there. 279/// @returns the index into the string table where the string is now located. 280size_t StringTable::insert(StringRef String) { 281 map::iterator i = Map.find(String); 282 283 if (i != Map.end()) 284 return i->second; 285 286 size_t Offset = Data.size(); 287 288 // Insert string data into string table. 289 Data.insert(Data.end(), String.begin(), String.end()); 290 Data.push_back('\0'); 291 292 // Put a reference to it in the map. 293 Map[String] = Offset; 294 295 // Update the internal length field. 296 update_length(); 297 298 return Offset; 299} 300 301//------------------------------------------------------------------------------ 302// WinCOFFObjectWriter class implementation 303 304WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, 305 raw_ostream &OS) 306 : MCObjectWriter(OS, true) 307 , TargetObjectWriter(MOTW) { 308 memset(&Header, 0, sizeof(Header)); 309 310 Header.Machine = TargetObjectWriter->getMachine(); 311} 312 313WinCOFFObjectWriter::~WinCOFFObjectWriter() { 314 for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I) 315 delete *I; 316 for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I) 317 delete *I; 318} 319 320COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) { 321 return createCOFFEntity<COFFSymbol>(Name, Symbols); 322} 323 324COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){ 325 symbol_map::iterator i = SymbolMap.find(Symbol); 326 if (i != SymbolMap.end()) 327 return i->second; 328 COFFSymbol *RetSymbol 329 = createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols); 330 SymbolMap[Symbol] = RetSymbol; 331 return RetSymbol; 332} 333 334COFFSection *WinCOFFObjectWriter::createSection(StringRef Name) { 335 return createCOFFEntity<COFFSection>(Name, Sections); 336} 337 338/// A template used to lookup or create a symbol/section, and initialize it if 339/// needed. 340template <typename object_t, typename list_t> 341object_t *WinCOFFObjectWriter::createCOFFEntity(StringRef Name, 342 list_t &List) { 343 object_t *Object = new object_t(Name); 344 345 List.push_back(Object); 346 347 return Object; 348} 349 350/// This function takes a section data object from the assembler 351/// and creates the associated COFF section staging object. 352void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) { 353 assert(SectionData.getSection().getVariant() == MCSection::SV_COFF 354 && "Got non COFF section in the COFF backend!"); 355 // FIXME: Not sure how to verify this (at least in a debug build). 356 MCSectionCOFF const &Sec = 357 static_cast<MCSectionCOFF const &>(SectionData.getSection()); 358 359 COFFSection *coff_section = createSection(Sec.getSectionName()); 360 COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName()); 361 362 coff_section->Symbol = coff_symbol; 363 coff_symbol->Section = coff_section; 364 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC; 365 366 // In this case the auxiliary symbol is a Section Definition. 367 coff_symbol->Aux.resize(1); 368 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0])); 369 coff_symbol->Aux[0].AuxType = ATSectionDefinition; 370 coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection(); 371 372 coff_section->Header.Characteristics = Sec.getCharacteristics(); 373 374 uint32_t &Characteristics = coff_section->Header.Characteristics; 375 switch (SectionData.getAlignment()) { 376 case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break; 377 case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break; 378 case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break; 379 case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break; 380 case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break; 381 case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break; 382 case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break; 383 case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break; 384 case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break; 385 case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break; 386 case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break; 387 case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break; 388 case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break; 389 case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break; 390 default: 391 llvm_unreachable("unsupported section alignment"); 392 } 393 394 // Bind internal COFF section to MC section. 395 coff_section->MCData = &SectionData; 396 SectionMap[&SectionData.getSection()] = coff_section; 397} 398 399/// This function takes a section data object from the assembler 400/// and creates the associated COFF symbol staging object. 401void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData, 402 MCAssembler &Assembler, 403 const MCAsmLayout &Layout) { 404 MCSymbol const &Symbol = SymbolData.getSymbol(); 405 COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&Symbol); 406 SymbolMap[&Symbol] = coff_symbol; 407 408 if (SymbolData.getFlags() & COFF::SF_WeakExternal) { 409 coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL; 410 411 if (Symbol.isVariable()) { 412 const MCSymbolRefExpr *SymRef = 413 dyn_cast<MCSymbolRefExpr>(Symbol.getVariableValue()); 414 415 if (!SymRef) 416 report_fatal_error("Weak externals may only alias symbols"); 417 418 coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol()); 419 } else { 420 std::string WeakName = std::string(".weak.") 421 + Symbol.getName().str() 422 + ".default"; 423 COFFSymbol *WeakDefault = createSymbol(WeakName); 424 WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE; 425 WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL; 426 WeakDefault->Data.Type = 0; 427 WeakDefault->Data.Value = 0; 428 coff_symbol->Other = WeakDefault; 429 } 430 431 // Setup the Weak External auxiliary symbol. 432 coff_symbol->Aux.resize(1); 433 memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0])); 434 coff_symbol->Aux[0].AuxType = ATWeakExternal; 435 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0; 436 coff_symbol->Aux[0].Aux.WeakExternal.Characteristics = 437 COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY; 438 439 coff_symbol->MCData = &SymbolData; 440 } else { 441 const MCSymbolData &ResSymData = 442 Assembler.getSymbolData(Symbol.AliasedSymbol()); 443 444 if (Symbol.isVariable()) { 445 int64_t Addr; 446 if (Symbol.getVariableValue()->EvaluateAsAbsolute(Addr, Layout)) 447 coff_symbol->Data.Value = Addr; 448 } 449 450 coff_symbol->Data.Type = (ResSymData.getFlags() & 0x0000FFFF) >> 0; 451 coff_symbol->Data.StorageClass = (ResSymData.getFlags() & 0x00FF0000) >> 16; 452 453 // If no storage class was specified in the streamer, define it here. 454 if (coff_symbol->Data.StorageClass == 0) { 455 bool external = ResSymData.isExternal() || (ResSymData.Fragment == NULL); 456 457 coff_symbol->Data.StorageClass = 458 external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC; 459 } 460 461 if (Symbol.isAbsolute() || Symbol.AliasedSymbol().isVariable()) 462 coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE; 463 else if (ResSymData.Fragment != NULL) 464 coff_symbol->Section = 465 SectionMap[&ResSymData.Fragment->getParent()->getSection()]; 466 467 coff_symbol->MCData = &ResSymData; 468 } 469} 470 471/// making a section real involves assigned it a number and putting 472/// name into the string table if needed 473void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) { 474 if (S.Name.size() > COFF::NameSize) { 475 const unsigned Max6DecimalSize = 999999; 476 const unsigned Max7DecimalSize = 9999999; 477 uint64_t StringTableEntry = Strings.insert(S.Name.c_str()); 478 479 if (StringTableEntry <= Max6DecimalSize) { 480 std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry)); 481 } else if (StringTableEntry <= Max7DecimalSize) { 482 // With seven digits, we have to skip the terminating null. Because 483 // sprintf always appends it, we use a larger temporary buffer. 484 char buffer[9] = { }; 485 std::sprintf(buffer, "/%d", unsigned(StringTableEntry)); 486 std::memcpy(S.Header.Name, buffer, 8); 487 } else { 488 report_fatal_error("COFF string table is greater than 9,999,999 bytes."); 489 } 490 } else 491 std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size()); 492 493 S.Number = Number; 494 S.Symbol->Data.SectionNumber = S.Number; 495 S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number; 496} 497 498void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) { 499 if (S.Name.size() > COFF::NameSize) { 500 size_t StringTableEntry = Strings.insert(S.Name.c_str()); 501 502 S.set_name_offset(StringTableEntry); 503 } else 504 std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size()); 505 S.Index = Index; 506} 507 508bool 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 520bool 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 528void 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 538void 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 548void 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 589void 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 603void 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 612void 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(); 622 i != e; i++) { 623 if (ExportSymbol(*i, Asm)) { 624 DefineSymbol(*i, Asm, Layout); 625 } 626 } 627} 628 629void 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 &Symbol = Target.getSymA()->getSymbol(); 638 const MCSymbol &A = Symbol.AliasedSymbol(); 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 Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup, 693 CrossSection); 694 695 // FIXME: Can anyone explain what this does other than adjust for the size 696 // of the offset? 697 if (Reloc.Data.Type == COFF::IMAGE_REL_AMD64_REL32 || 698 Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32) 699 FixedValue += 4; 700 701 coff_section->Relocations.push_back(Reloc); 702} 703 704void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm, 705 const MCAsmLayout &Layout) { 706 // Assign symbol and section indexes and offsets. 707 Header.NumberOfSections = 0; 708 709 DenseMap<COFFSection *, uint16_t> SectionIndices; 710 for (sections::iterator i = Sections.begin(), 711 e = Sections.end(); i != e; i++) { 712 if (Layout.getSectionAddressSize((*i)->MCData) > 0) { 713 size_t Number = ++Header.NumberOfSections; 714 SectionIndices[*i] = Number; 715 MakeSectionReal(**i, Number); 716 } else { 717 (*i)->Number = -1; 718 } 719 } 720 721 Header.NumberOfSymbols = 0; 722 723 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) { 724 COFFSymbol *coff_symbol = *i; 725 MCSymbolData const *SymbolData = coff_symbol->MCData; 726 727 // Update section number & offset for symbols that have them. 728 if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) { 729 assert(coff_symbol->Section != NULL); 730 731 coff_symbol->Data.SectionNumber = coff_symbol->Section->Number; 732 coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment) 733 + SymbolData->Offset; 734 } 735 736 if (coff_symbol->should_keep()) { 737 MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++); 738 739 // Update auxiliary symbol info. 740 coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size(); 741 Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols; 742 } else 743 coff_symbol->Index = -1; 744 } 745 746 // Fixup weak external references. 747 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) { 748 COFFSymbol *coff_symbol = *i; 749 if (coff_symbol->Other != NULL) { 750 assert(coff_symbol->Index != -1); 751 assert(coff_symbol->Aux.size() == 1 && 752 "Symbol must contain one aux symbol!"); 753 assert(coff_symbol->Aux[0].AuxType == ATWeakExternal && 754 "Symbol's aux symbol must be a Weak External!"); 755 coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index; 756 } 757 } 758 759 // Fixup associative COMDAT sections. 760 for (sections::iterator i = Sections.begin(), 761 e = Sections.end(); i != e; i++) { 762 if ((*i)->Symbol->Aux[0].Aux.SectionDefinition.Selection != 763 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) 764 continue; 765 766 const MCSectionCOFF &MCSec = static_cast<const MCSectionCOFF &>( 767 (*i)->MCData->getSection()); 768 769 COFFSection *Assoc = SectionMap.lookup(MCSec.getAssocSection()); 770 if (!Assoc) { 771 report_fatal_error(Twine("Missing associated COMDAT section ") + 772 MCSec.getAssocSection()->getSectionName() + 773 " for section " + MCSec.getSectionName()); 774 } 775 776 // Skip this section if the associated section is unused. 777 if (Assoc->Number == -1) 778 continue; 779 780 (*i)->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc]; 781 } 782 783 784 // Assign file offsets to COFF object file structures. 785 786 unsigned offset = 0; 787 788 offset += COFF::HeaderSize; 789 offset += COFF::SectionSize * Header.NumberOfSections; 790 791 for (MCAssembler::const_iterator i = Asm.begin(), 792 e = Asm.end(); 793 i != e; i++) { 794 COFFSection *Sec = SectionMap[&i->getSection()]; 795 796 if (Sec->Number == -1) 797 continue; 798 799 Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i); 800 801 if (IsPhysicalSection(Sec)) { 802 Sec->Header.PointerToRawData = offset; 803 804 offset += Sec->Header.SizeOfRawData; 805 } 806 807 if (Sec->Relocations.size() > 0) { 808 bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff; 809 810 if (RelocationsOverflow) { 811 // Signal overflow by setting NumberOfSections to max value. Actual 812 // size is found in reloc #0. Microsoft tools understand this. 813 Sec->Header.NumberOfRelocations = 0xffff; 814 } else { 815 Sec->Header.NumberOfRelocations = Sec->Relocations.size(); 816 } 817 Sec->Header.PointerToRelocations = offset; 818 819 if (RelocationsOverflow) { 820 // Reloc #0 will contain actual count, so make room for it. 821 offset += COFF::RelocationSize; 822 } 823 824 offset += COFF::RelocationSize * Sec->Relocations.size(); 825 826 for (relocations::iterator cr = Sec->Relocations.begin(), 827 er = Sec->Relocations.end(); 828 cr != er; ++cr) { 829 assert((*cr).Symb->Index != -1); 830 (*cr).Data.SymbolTableIndex = (*cr).Symb->Index; 831 } 832 } 833 834 assert(Sec->Symbol->Aux.size() == 1 835 && "Section's symbol must have one aux!"); 836 AuxSymbol &Aux = Sec->Symbol->Aux[0]; 837 assert(Aux.AuxType == ATSectionDefinition && 838 "Section's symbol's aux symbol must be a Section Definition!"); 839 Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData; 840 Aux.Aux.SectionDefinition.NumberOfRelocations = 841 Sec->Header.NumberOfRelocations; 842 Aux.Aux.SectionDefinition.NumberOfLinenumbers = 843 Sec->Header.NumberOfLineNumbers; 844 } 845 846 Header.PointerToSymbolTable = offset; 847 848 Header.TimeDateStamp = sys::TimeValue::now().toEpochTime(); 849 850 // Write it all to disk... 851 WriteFileHeader(Header); 852 853 { 854 sections::iterator i, ie; 855 MCAssembler::const_iterator j, je; 856 857 for (i = Sections.begin(), ie = Sections.end(); i != ie; i++) 858 if ((*i)->Number != -1) { 859 if ((*i)->Relocations.size() >= 0xffff) { 860 (*i)->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL; 861 } 862 WriteSectionHeader((*i)->Header); 863 } 864 865 for (i = Sections.begin(), ie = Sections.end(), 866 j = Asm.begin(), je = Asm.end(); 867 (i != ie) && (j != je); ++i, ++j) { 868 869 if ((*i)->Number == -1) 870 continue; 871 872 if ((*i)->Header.PointerToRawData != 0) { 873 assert(OS.tell() == (*i)->Header.PointerToRawData && 874 "Section::PointerToRawData is insane!"); 875 876 Asm.writeSectionData(j, Layout); 877 } 878 879 if ((*i)->Relocations.size() > 0) { 880 assert(OS.tell() == (*i)->Header.PointerToRelocations && 881 "Section::PointerToRelocations is insane!"); 882 883 if ((*i)->Relocations.size() >= 0xffff) { 884 // In case of overflow, write actual relocation count as first 885 // relocation. Including the synthetic reloc itself (+ 1). 886 COFF::relocation r; 887 r.VirtualAddress = (*i)->Relocations.size() + 1; 888 r.SymbolTableIndex = 0; 889 r.Type = 0; 890 WriteRelocation(r); 891 } 892 893 for (relocations::const_iterator k = (*i)->Relocations.begin(), 894 ke = (*i)->Relocations.end(); 895 k != ke; k++) { 896 WriteRelocation(k->Data); 897 } 898 } else 899 assert((*i)->Header.PointerToRelocations == 0 && 900 "Section::PointerToRelocations is insane!"); 901 } 902 } 903 904 assert(OS.tell() == Header.PointerToSymbolTable && 905 "Header::PointerToSymbolTable is insane!"); 906 907 for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) 908 if ((*i)->Index != -1) 909 WriteSymbol(*i); 910 911 OS.write((char const *)&Strings.Data.front(), Strings.Data.size()); 912} 913 914MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) : 915 Machine(Machine_) { 916} 917 918// Pin the vtable to this file. 919void MCWinCOFFObjectTargetWriter::anchor() {} 920 921//------------------------------------------------------------------------------ 922// WinCOFFObjectWriter factory function 923 924namespace llvm { 925 MCObjectWriter *createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, 926 raw_ostream &OS) { 927 return new WinCOFFObjectWriter(MOTW, OS); 928 } 929} 930