lib/MC/WinCOFFObjectWriter.cpp

   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/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 }