tools/dsymutil/DwarfStreamer.cpp

   1 //===- tools/dsymutil/DwarfStreamer.cpp - Dwarf Streamer ------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "DwarfStreamer.h"
  10 #include "CompileUnit.h"
  11 #include "LinkUtils.h"
  12 #include "MachOUtils.h"
  13 #include "llvm/ADT/Triple.h"
  14 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
  15 #include "llvm/MC/MCTargetOptions.h"
  16 #include "llvm/MC/MCTargetOptionsCommandFlags.inc"
  17 #include "llvm/Support/LEB128.h"
  18 #include "llvm/Support/TargetRegistry.h"
  19 #include "llvm/Target/TargetMachine.h"
  20 #include "llvm/Target/TargetOptions.h"
  21
  22 namespace llvm {
  23 namespace dsymutil {
  24
  25 /// Retrieve the section named \a SecName in \a Obj.
  26 ///
  27 /// To accommodate for platform discrepancies, the name passed should be
  28 /// (for example) 'debug_info' to match either '__debug_info' or '.debug_info'.
  29 /// This function will strip the initial platform-specific characters.
  30 static Optional<object::SectionRef>
  31 getSectionByName(const object::ObjectFile &Obj, StringRef SecName) {
  32   for (const object::SectionRef &Section : Obj.sections()) {
  33     StringRef SectionName;
  34     if (Expected<StringRef> NameOrErr = Section.getName())
  35       SectionName = *NameOrErr;
  36     else
  37       consumeError(NameOrErr.takeError());
  38
  39     SectionName = SectionName.substr(SectionName.find_first_not_of("._"));
  40     if (SectionName != SecName)
  41       continue;
  42     return Section;
  43   }
  44   return None;
  45 }
  46
  47 bool DwarfStreamer::init(Triple TheTriple) {
  48   std::string ErrorStr;
  49   std::string TripleName;
  50   StringRef Context = "dwarf streamer init";
  51
  52   // Get the target.
  53   const Target *TheTarget =
  54       TargetRegistry::lookupTarget(TripleName, TheTriple, ErrorStr);
  55   if (!TheTarget)
  56     return error(ErrorStr, Context);
  57   TripleName = TheTriple.getTriple();
  58
  59   // Create all the MC Objects.
  60   MRI.reset(TheTarget->createMCRegInfo(TripleName));
  61   if (!MRI)
  62     return error(Twine("no register info for target ") + TripleName, Context);
  63
  64   MAI.reset(TheTarget->createMCAsmInfo(*MRI, TripleName));
  65   if (!MAI)
  66     return error("no asm info for target " + TripleName, Context);
  67
  68   MOFI.reset(new MCObjectFileInfo);
  69   MC.reset(new MCContext(MAI.get(), MRI.get(), MOFI.get()));
  70   MOFI->InitMCObjectFileInfo(TheTriple, /*PIC*/ false, *MC);
  71
  72   MSTI.reset(TheTarget->createMCSubtargetInfo(TripleName, "", ""));
  73   if (!MSTI)
  74     return error("no subtarget info for target " + TripleName, Context);
  75
  76   MCTargetOptions MCOptions = InitMCTargetOptionsFromFlags();
  77   MAB = TheTarget->createMCAsmBackend(*MSTI, *MRI, MCOptions);
  78   if (!MAB)
  79     return error("no asm backend for target " + TripleName, Context);
  80
  81   MII.reset(TheTarget->createMCInstrInfo());
  82   if (!MII)
  83     return error("no instr info info for target " + TripleName, Context);
  84
  85   MCE = TheTarget->createMCCodeEmitter(*MII, *MRI, *MC);
  86   if (!MCE)
  87     return error("no code emitter for target " + TripleName, Context);
  88
  89   switch (Options.FileType) {
  90   case OutputFileType::Assembly: {
  91     MIP = TheTarget->createMCInstPrinter(TheTriple, MAI->getAssemblerDialect(),
  92                                          *MAI, *MII, *MRI);
  93     MS = TheTarget->createAsmStreamer(
  94         *MC, std::make_unique<formatted_raw_ostream>(OutFile), true, true, MIP,
  95         std::unique_ptr<MCCodeEmitter>(MCE), std::unique_ptr<MCAsmBackend>(MAB),
  96         true);
  97     break;
  98   }
  99   case OutputFileType::Object: {
 100     MS = TheTarget->createMCObjectStreamer(
 101         TheTriple, *MC, std::unique_ptr<MCAsmBackend>(MAB),
 102         MAB->createObjectWriter(OutFile), std::unique_ptr<MCCodeEmitter>(MCE),
 103         *MSTI, MCOptions.MCRelaxAll, MCOptions.MCIncrementalLinkerCompatible,
 104         /*DWARFMustBeAtTheEnd*/ false);
 105     break;
 106   }
 107   }
 108
 109   if (!MS)
 110     return error("no object streamer for target " + TripleName, Context);
 111
 112   // Finally create the AsmPrinter we'll use to emit the DIEs.
 113   TM.reset(TheTarget->createTargetMachine(TripleName, "", "", TargetOptions(),
 114                                           None));
 115   if (!TM)
 116     return error("no target machine for target " + TripleName, Context);
 117
 118   Asm.reset(TheTarget->createAsmPrinter(*TM, std::unique_ptr<MCStreamer>(MS)));
 119   if (!Asm)
 120     return error("no asm printer for target " + TripleName, Context);
 121
 122   RangesSectionSize = 0;
 123   LocSectionSize = 0;
 124   LineSectionSize = 0;
 125   FrameSectionSize = 0;
 126
 127   return true;
 128 }
 129
 130 bool DwarfStreamer::finish(const DebugMap &DM, SymbolMapTranslator &T) {
 131   bool Result = true;
 132   if (DM.getTriple().isOSDarwin() && !DM.getBinaryPath().empty() &&
 133       Options.FileType == OutputFileType::Object)
 134     Result = MachOUtils::generateDsymCompanion(DM, T, *MS, OutFile);
 135   else
 136     MS->Finish();
 137   return Result;
 138 }
 139
 140 void DwarfStreamer::switchToDebugInfoSection(unsigned DwarfVersion) {
 141   MS->SwitchSection(MOFI->getDwarfInfoSection());
 142   MC->setDwarfVersion(DwarfVersion);
 143 }
 144
 145 /// Emit the compilation unit header for \p Unit in the debug_info section.
 146 ///
 147 /// A Dwarf section header is encoded as:
 148 ///  uint32_t   Unit length (omitting this field)
 149 ///  uint16_t   Version
 150 ///  uint32_t   Abbreviation table offset
 151 ///  uint8_t    Address size
 152 ///
 153 /// Leading to a total of 11 bytes.
 154 void DwarfStreamer::emitCompileUnitHeader(CompileUnit &Unit) {
 155   unsigned Version = Unit.getOrigUnit().getVersion();
 156   switchToDebugInfoSection(Version);
 157
 158   /// The start of the unit within its section.
 159   Unit.setLabelBegin(Asm->createTempSymbol("cu_begin"));
 160   Asm->OutStreamer->EmitLabel(Unit.getLabelBegin());
 161
 162   // Emit size of content not including length itself. The size has already
 163   // been computed in CompileUnit::computeOffsets(). Subtract 4 to that size to
 164   // account for the length field.
 165   Asm->emitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset() - 4);
 166   Asm->emitInt16(Version);
 167
 168   // We share one abbreviations table across all units so it's always at the
 169   // start of the section.
 170   Asm->emitInt32(0);
 171   Asm->emitInt8(Unit.getOrigUnit().getAddressByteSize());
 172
 173   // Remember this CU.
 174   EmittedUnits.push_back({Unit.getUniqueID(), Unit.getLabelBegin()});
 175 }
 176
 177 /// Emit the \p Abbrevs array as the shared abbreviation table
 178 /// for the linked Dwarf file.
 179 void DwarfStreamer::emitAbbrevs(
 180     const std::vector<std::unique_ptr<DIEAbbrev>> &Abbrevs,
 181     unsigned DwarfVersion) {
 182   MS->SwitchSection(MOFI->getDwarfAbbrevSection());
 183   MC->setDwarfVersion(DwarfVersion);
 184   Asm->emitDwarfAbbrevs(Abbrevs);
 185 }
 186
 187 /// Recursively emit the DIE tree rooted at \p Die.
 188 void DwarfStreamer::emitDIE(DIE &Die) {
 189   MS->SwitchSection(MOFI->getDwarfInfoSection());
 190   Asm->emitDwarfDIE(Die);
 191 }
 192
 193 /// Emit the debug_str section stored in \p Pool.
 194 void DwarfStreamer::emitStrings(const NonRelocatableStringpool &Pool) {
 195   Asm->OutStreamer->SwitchSection(MOFI->getDwarfStrSection());
 196   std::vector<DwarfStringPoolEntryRef> Entries = Pool.getEntriesForEmission();
 197   for (auto Entry : Entries) {
 198     // Emit the string itself.
 199     Asm->OutStreamer->EmitBytes(Entry.getString());
 200     // Emit a null terminator.
 201     Asm->emitInt8(0);
 202   }
 203 }
 204
 205 void DwarfStreamer::emitDebugNames(
 206     AccelTable<DWARF5AccelTableStaticData> &Table) {
 207   if (EmittedUnits.empty())
 208     return;
 209
 210   // Build up data structures needed to emit this section.
 211   std::vector<MCSymbol *> CompUnits;
 212   DenseMap<unsigned, size_t> UniqueIdToCuMap;
 213   unsigned Id = 0;
 214   for (auto &CU : EmittedUnits) {
 215     CompUnits.push_back(CU.LabelBegin);
 216     // We might be omitting CUs, so we need to remap them.
 217     UniqueIdToCuMap[CU.ID] = Id++;
 218   }
 219
 220   Asm->OutStreamer->SwitchSection(MOFI->getDwarfDebugNamesSection());
 221   emitDWARF5AccelTable(
 222       Asm.get(), Table, CompUnits,
 223       [&UniqueIdToCuMap](const DWARF5AccelTableStaticData &Entry) {
 224         return UniqueIdToCuMap[Entry.getCUIndex()];
 225       });
 226 }
 227
 228 void DwarfStreamer::emitAppleNamespaces(
 229     AccelTable<AppleAccelTableStaticOffsetData> &Table) {
 230   Asm->OutStreamer->SwitchSection(MOFI->getDwarfAccelNamespaceSection());
 231   auto *SectionBegin = Asm->createTempSymbol("namespac_begin");
 232   Asm->OutStreamer->EmitLabel(SectionBegin);
 233   emitAppleAccelTable(Asm.get(), Table, "namespac", SectionBegin);
 234 }
 235
 236 void DwarfStreamer::emitAppleNames(
 237     AccelTable<AppleAccelTableStaticOffsetData> &Table) {
 238   Asm->OutStreamer->SwitchSection(MOFI->getDwarfAccelNamesSection());
 239   auto *SectionBegin = Asm->createTempSymbol("names_begin");
 240   Asm->OutStreamer->EmitLabel(SectionBegin);
 241   emitAppleAccelTable(Asm.get(), Table, "names", SectionBegin);
 242 }
 243
 244 void DwarfStreamer::emitAppleObjc(
 245     AccelTable<AppleAccelTableStaticOffsetData> &Table) {
 246   Asm->OutStreamer->SwitchSection(MOFI->getDwarfAccelObjCSection());
 247   auto *SectionBegin = Asm->createTempSymbol("objc_begin");
 248   Asm->OutStreamer->EmitLabel(SectionBegin);
 249   emitAppleAccelTable(Asm.get(), Table, "objc", SectionBegin);
 250 }
 251
 252 void DwarfStreamer::emitAppleTypes(
 253     AccelTable<AppleAccelTableStaticTypeData> &Table) {
 254   Asm->OutStreamer->SwitchSection(MOFI->getDwarfAccelTypesSection());
 255   auto *SectionBegin = Asm->createTempSymbol("types_begin");
 256   Asm->OutStreamer->EmitLabel(SectionBegin);
 257   emitAppleAccelTable(Asm.get(), Table, "types", SectionBegin);
 258 }
 259
 260 /// Emit the swift_ast section stored in \p Buffers.
 261 void DwarfStreamer::emitSwiftAST(StringRef Buffer) {
 262   MCSection *SwiftASTSection = MOFI->getDwarfSwiftASTSection();
 263   SwiftASTSection->setAlignment(llvm::Align(32));
 264   MS->SwitchSection(SwiftASTSection);
 265   MS->EmitBytes(Buffer);
 266 }
 267
 268 /// Emit the debug_range section contents for \p FuncRange by
 269 /// translating the original \p Entries. The debug_range section
 270 /// format is totally trivial, consisting just of pairs of address
 271 /// sized addresses describing the ranges.
 272 void DwarfStreamer::emitRangesEntries(
 273     int64_t UnitPcOffset, uint64_t OrigLowPc,
 274     const FunctionIntervals::const_iterator &FuncRange,
 275     const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
 276     unsigned AddressSize) {
 277   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
 278
 279   // Offset each range by the right amount.
 280   int64_t PcOffset = Entries.empty() ? 0 : FuncRange.value() + UnitPcOffset;
 281   for (const auto &Range : Entries) {
 282     if (Range.isBaseAddressSelectionEntry(AddressSize)) {
 283       warn("unsupported base address selection operation",
 284            "emitting debug_ranges");
 285       break;
 286     }
 287     // Do not emit empty ranges.
 288     if (Range.StartAddress == Range.EndAddress)
 289       continue;
 290
 291     // All range entries should lie in the function range.
 292     if (!(Range.StartAddress + OrigLowPc >= FuncRange.start() &&
 293           Range.EndAddress + OrigLowPc <= FuncRange.stop()))
 294       warn("inconsistent range data.", "emitting debug_ranges");
 295     MS->EmitIntValue(Range.StartAddress + PcOffset, AddressSize);
 296     MS->EmitIntValue(Range.EndAddress + PcOffset, AddressSize);
 297     RangesSectionSize += 2 * AddressSize;
 298   }
 299
 300   // Add the terminator entry.
 301   MS->EmitIntValue(0, AddressSize);
 302   MS->EmitIntValue(0, AddressSize);
 303   RangesSectionSize += 2 * AddressSize;
 304 }
 305
 306 /// Emit the debug_aranges contribution of a unit and
 307 /// if \p DoDebugRanges is true the debug_range contents for a
 308 /// compile_unit level DW_AT_ranges attribute (Which are basically the
 309 /// same thing with a different base address).
 310 /// Just aggregate all the ranges gathered inside that unit.
 311 void DwarfStreamer::emitUnitRangesEntries(CompileUnit &Unit,
 312                                           bool DoDebugRanges) {
 313   unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
 314   // Gather the ranges in a vector, so that we can simplify them. The
 315   // IntervalMap will have coalesced the non-linked ranges, but here
 316   // we want to coalesce the linked addresses.
 317   std::vector<std::pair<uint64_t, uint64_t>> Ranges;
 318   const auto &FunctionRanges = Unit.getFunctionRanges();
 319   for (auto Range = FunctionRanges.begin(), End = FunctionRanges.end();
 320        Range != End; ++Range)
 321     Ranges.push_back(std::make_pair(Range.start() + Range.value(),
 322                                     Range.stop() + Range.value()));
 323
 324   // The object addresses where sorted, but again, the linked
 325   // addresses might end up in a different order.
 326   llvm::sort(Ranges);
 327
 328   if (!Ranges.empty()) {
 329     MS->SwitchSection(MC->getObjectFileInfo()->getDwarfARangesSection());
 330
 331     MCSymbol *BeginLabel = Asm->createTempSymbol("Barange");
 332     MCSymbol *EndLabel = Asm->createTempSymbol("Earange");
 333
 334     unsigned HeaderSize =
 335         sizeof(int32_t) + // Size of contents (w/o this field
 336         sizeof(int16_t) + // DWARF ARange version number
 337         sizeof(int32_t) + // Offset of CU in the .debug_info section
 338         sizeof(int8_t) +  // Pointer Size (in bytes)
 339         sizeof(int8_t);   // Segment Size (in bytes)
 340
 341     unsigned TupleSize = AddressSize * 2;
 342     unsigned Padding = offsetToAlignment(HeaderSize, llvm::Align(TupleSize));
 343
 344     Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Arange length
 345     Asm->OutStreamer->EmitLabel(BeginLabel);
 346     Asm->emitInt16(dwarf::DW_ARANGES_VERSION); // Version number
 347     Asm->emitInt32(Unit.getStartOffset());     // Corresponding unit's offset
 348     Asm->emitInt8(AddressSize);                // Address size
 349     Asm->emitInt8(0);                          // Segment size
 350
 351     Asm->OutStreamer->emitFill(Padding, 0x0);
 352
 353     for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End;
 354          ++Range) {
 355       uint64_t RangeStart = Range->first;
 356       MS->EmitIntValue(RangeStart, AddressSize);
 357       while ((Range + 1) != End && Range->second == (Range + 1)->first)
 358         ++Range;
 359       MS->EmitIntValue(Range->second - RangeStart, AddressSize);
 360     }
 361
 362     // Emit terminator
 363     Asm->OutStreamer->EmitIntValue(0, AddressSize);
 364     Asm->OutStreamer->EmitIntValue(0, AddressSize);
 365     Asm->OutStreamer->EmitLabel(EndLabel);
 366   }
 367
 368   if (!DoDebugRanges)
 369     return;
 370
 371   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
 372   // Offset each range by the right amount.
 373   int64_t PcOffset = -Unit.getLowPc();
 374   // Emit coalesced ranges.
 375   for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End; ++Range) {
 376     MS->EmitIntValue(Range->first + PcOffset, AddressSize);
 377     while (Range + 1 != End && Range->second == (Range + 1)->first)
 378       ++Range;
 379     MS->EmitIntValue(Range->second + PcOffset, AddressSize);
 380     RangesSectionSize += 2 * AddressSize;
 381   }
 382
 383   // Add the terminator entry.
 384   MS->EmitIntValue(0, AddressSize);
 385   MS->EmitIntValue(0, AddressSize);
 386   RangesSectionSize += 2 * AddressSize;
 387 }
 388
 389 /// Emit location lists for \p Unit and update attributes to point to the new
 390 /// entries.
 391 void DwarfStreamer::emitLocationsForUnit(
 392     const CompileUnit &Unit, DWARFContext &Dwarf,
 393     std::function<void(StringRef, SmallVectorImpl<uint8_t> &)> ProcessExpr) {
 394   const auto &Attributes = Unit.getLocationAttributes();
 395
 396   if (Attributes.empty())
 397     return;
 398
 399   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLocSection());
 400
 401   unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
 402   const DWARFSection &InputSec = Dwarf.getDWARFObj().getLocSection();
 403   DataExtractor Data(InputSec.Data, Dwarf.isLittleEndian(), AddressSize);
 404   DWARFUnit &OrigUnit = Unit.getOrigUnit();
 405   auto OrigUnitDie = OrigUnit.getUnitDIE(false);
 406   int64_t UnitPcOffset = 0;
 407   if (auto OrigLowPc = dwarf::toAddress(OrigUnitDie.find(dwarf::DW_AT_low_pc)))
 408     UnitPcOffset = int64_t(*OrigLowPc) - Unit.getLowPc();
 409
 410   SmallVector<uint8_t, 32> Buffer;
 411   for (const auto &Attr : Attributes) {
 412     uint64_t Offset = Attr.first.get();
 413     Attr.first.set(LocSectionSize);
 414     // This is the quantity to add to the old location address to get
 415     // the correct address for the new one.
 416     int64_t LocPcOffset = Attr.second + UnitPcOffset;
 417     while (Data.isValidOffset(Offset)) {
 418       uint64_t Low = Data.getUnsigned(&Offset, AddressSize);
 419       uint64_t High = Data.getUnsigned(&Offset, AddressSize);
 420       LocSectionSize += 2 * AddressSize;
 421       if (Low == 0 && High == 0) {
 422         Asm->OutStreamer->EmitIntValue(0, AddressSize);
 423         Asm->OutStreamer->EmitIntValue(0, AddressSize);
 424         break;
 425       }
 426       Asm->OutStreamer->EmitIntValue(Low + LocPcOffset, AddressSize);
 427       Asm->OutStreamer->EmitIntValue(High + LocPcOffset, AddressSize);
 428       uint64_t Length = Data.getU16(&Offset);
 429       Asm->OutStreamer->EmitIntValue(Length, 2);
 430       // Copy the bytes into to the buffer, process them, emit them.
 431       Buffer.reserve(Length);
 432       Buffer.resize(0);
 433       StringRef Input = InputSec.Data.substr(Offset, Length);
 434       ProcessExpr(Input, Buffer);
 435       Asm->OutStreamer->EmitBytes(
 436           StringRef((const char *)Buffer.data(), Length));
 437       Offset += Length;
 438       LocSectionSize += Length + 2;
 439     }
 440   }
 441 }
 442
 443 void DwarfStreamer::emitLineTableForUnit(MCDwarfLineTableParams Params,
 444                                          StringRef PrologueBytes,
 445                                          unsigned MinInstLength,
 446                                          std::vector<DWARFDebugLine::Row> &Rows,
 447                                          unsigned PointerSize) {
 448   // Switch to the section where the table will be emitted into.
 449   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection());
 450   MCSymbol *LineStartSym = MC->createTempSymbol();
 451   MCSymbol *LineEndSym = MC->createTempSymbol();
 452
 453   // The first 4 bytes is the total length of the information for this
 454   // compilation unit (not including these 4 bytes for the length).
 455   Asm->EmitLabelDifference(LineEndSym, LineStartSym, 4);
 456   Asm->OutStreamer->EmitLabel(LineStartSym);
 457   // Copy Prologue.
 458   MS->EmitBytes(PrologueBytes);
 459   LineSectionSize += PrologueBytes.size() + 4;
 460
 461   SmallString<128> EncodingBuffer;
 462   raw_svector_ostream EncodingOS(EncodingBuffer);
 463
 464   if (Rows.empty()) {
 465     // We only have the dummy entry, dsymutil emits an entry with a 0
 466     // address in that case.
 467     MCDwarfLineAddr::Encode(*MC, Params, std::numeric_limits<int64_t>::max(), 0,
 468                             EncodingOS);
 469     MS->EmitBytes(EncodingOS.str());
 470     LineSectionSize += EncodingBuffer.size();
 471     MS->EmitLabel(LineEndSym);
 472     return;
 473   }
 474
 475   // Line table state machine fields
 476   unsigned FileNum = 1;
 477   unsigned LastLine = 1;
 478   unsigned Column = 0;
 479   unsigned IsStatement = 1;
 480   unsigned Isa = 0;
 481   uint64_t Address = -1ULL;
 482
 483   unsigned RowsSinceLastSequence = 0;
 484
 485   for (unsigned Idx = 0; Idx < Rows.size(); ++Idx) {
 486     auto &Row = Rows[Idx];
 487
 488     int64_t AddressDelta;
 489     if (Address == -1ULL) {
 490       MS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
 491       MS->EmitULEB128IntValue(PointerSize + 1);
 492       MS->EmitIntValue(dwarf::DW_LNE_set_address, 1);
 493       MS->EmitIntValue(Row.Address.Address, PointerSize);
 494       LineSectionSize += 2 + PointerSize + getULEB128Size(PointerSize + 1);
 495       AddressDelta = 0;
 496     } else {
 497       AddressDelta = (Row.Address.Address - Address) / MinInstLength;
 498     }
 499
 500     // FIXME: code copied and transformed from MCDwarf.cpp::EmitDwarfLineTable.
 501     // We should find a way to share this code, but the current compatibility
 502     // requirement with classic dsymutil makes it hard. Revisit that once this
 503     // requirement is dropped.
 504
 505     if (FileNum != Row.File) {
 506       FileNum = Row.File;
 507       MS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
 508       MS->EmitULEB128IntValue(FileNum);
 509       LineSectionSize += 1 + getULEB128Size(FileNum);
 510     }
 511     if (Column != Row.Column) {
 512       Column = Row.Column;
 513       MS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
 514       MS->EmitULEB128IntValue(Column);
 515       LineSectionSize += 1 + getULEB128Size(Column);
 516     }
 517
 518     // FIXME: We should handle the discriminator here, but dsymutil doesn't
 519     // consider it, thus ignore it for now.
 520
 521     if (Isa != Row.Isa) {
 522       Isa = Row.Isa;
 523       MS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
 524       MS->EmitULEB128IntValue(Isa);
 525       LineSectionSize += 1 + getULEB128Size(Isa);
 526     }
 527     if (IsStatement != Row.IsStmt) {
 528       IsStatement = Row.IsStmt;
 529       MS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
 530       LineSectionSize += 1;
 531     }
 532     if (Row.BasicBlock) {
 533       MS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
 534       LineSectionSize += 1;
 535     }
 536
 537     if (Row.PrologueEnd) {
 538       MS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
 539       LineSectionSize += 1;
 540     }
 541
 542     if (Row.EpilogueBegin) {
 543       MS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
 544       LineSectionSize += 1;
 545     }
 546
 547     int64_t LineDelta = int64_t(Row.Line) - LastLine;
 548     if (!Row.EndSequence) {
 549       MCDwarfLineAddr::Encode(*MC, Params, LineDelta, AddressDelta, EncodingOS);
 550       MS->EmitBytes(EncodingOS.str());
 551       LineSectionSize += EncodingBuffer.size();
 552       EncodingBuffer.resize(0);
 553       Address = Row.Address.Address;
 554       LastLine = Row.Line;
 555       RowsSinceLastSequence++;
 556     } else {
 557       if (LineDelta) {
 558         MS->EmitIntValue(dwarf::DW_LNS_advance_line, 1);
 559         MS->EmitSLEB128IntValue(LineDelta);
 560         LineSectionSize += 1 + getSLEB128Size(LineDelta);
 561       }
 562       if (AddressDelta) {
 563         MS->EmitIntValue(dwarf::DW_LNS_advance_pc, 1);
 564         MS->EmitULEB128IntValue(AddressDelta);
 565         LineSectionSize += 1 + getULEB128Size(AddressDelta);
 566       }
 567       MCDwarfLineAddr::Encode(*MC, Params, std::numeric_limits<int64_t>::max(),
 568                               0, EncodingOS);
 569       MS->EmitBytes(EncodingOS.str());
 570       LineSectionSize += EncodingBuffer.size();
 571       EncodingBuffer.resize(0);
 572       Address = -1ULL;
 573       LastLine = FileNum = IsStatement = 1;
 574       RowsSinceLastSequence = Column = Isa = 0;
 575     }
 576   }
 577
 578   if (RowsSinceLastSequence) {
 579     MCDwarfLineAddr::Encode(*MC, Params, std::numeric_limits<int64_t>::max(), 0,
 580                             EncodingOS);
 581     MS->EmitBytes(EncodingOS.str());
 582     LineSectionSize += EncodingBuffer.size();
 583     EncodingBuffer.resize(0);
 584   }
 585
 586   MS->EmitLabel(LineEndSym);
 587 }
 588
 589 /// Copy the debug_line over to the updated binary while unobfuscating the file
 590 /// names and directories.
 591 void DwarfStreamer::translateLineTable(DataExtractor Data, uint64_t Offset) {
 592   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection());
 593   StringRef Contents = Data.getData();
 594
 595   // We have to deconstruct the line table header, because it contains to
 596   // length fields that will need to be updated when we change the length of
 597   // the files and directories in there.
 598   unsigned UnitLength = Data.getU32(&Offset);
 599   uint64_t UnitEnd = Offset + UnitLength;
 600   MCSymbol *BeginLabel = MC->createTempSymbol();
 601   MCSymbol *EndLabel = MC->createTempSymbol();
 602   unsigned Version = Data.getU16(&Offset);
 603
 604   if (Version > 5) {
 605     warn("Unsupported line table version: dropping contents and not "
 606          "unobfsucating line table.");
 607     return;
 608   }
 609
 610   Asm->EmitLabelDifference(EndLabel, BeginLabel, 4);
 611   Asm->OutStreamer->EmitLabel(BeginLabel);
 612   Asm->emitInt16(Version);
 613   LineSectionSize += 6;
 614
 615   MCSymbol *HeaderBeginLabel = MC->createTempSymbol();
 616   MCSymbol *HeaderEndLabel = MC->createTempSymbol();
 617   Asm->EmitLabelDifference(HeaderEndLabel, HeaderBeginLabel, 4);
 618   Asm->OutStreamer->EmitLabel(HeaderBeginLabel);
 619   Offset += 4;
 620   LineSectionSize += 4;
 621
 622   uint64_t AfterHeaderLengthOffset = Offset;
 623   // Skip to the directories.
 624   Offset += (Version >= 4) ? 5 : 4;
 625   unsigned OpcodeBase = Data.getU8(&Offset);
 626   Offset += OpcodeBase - 1;
 627   Asm->OutStreamer->EmitBytes(Contents.slice(AfterHeaderLengthOffset, Offset));
 628   LineSectionSize += Offset - AfterHeaderLengthOffset;
 629
 630   // Offset points to the first directory.
 631   while (const char *Dir = Data.getCStr(&Offset)) {
 632     if (Dir[0] == 0)
 633       break;
 634
 635     StringRef Translated = Options.Translator(Dir);
 636     Asm->OutStreamer->EmitBytes(Translated);
 637     Asm->emitInt8(0);
 638     LineSectionSize += Translated.size() + 1;
 639   }
 640   Asm->emitInt8(0);
 641   LineSectionSize += 1;
 642
 643   while (const char *File = Data.getCStr(&Offset)) {
 644     if (File[0] == 0)
 645       break;
 646
 647     StringRef Translated = Options.Translator(File);
 648     Asm->OutStreamer->EmitBytes(Translated);
 649     Asm->emitInt8(0);
 650     LineSectionSize += Translated.size() + 1;
 651
 652     uint64_t OffsetBeforeLEBs = Offset;
 653     Asm->EmitULEB128(Data.getULEB128(&Offset));
 654     Asm->EmitULEB128(Data.getULEB128(&Offset));
 655     Asm->EmitULEB128(Data.getULEB128(&Offset));
 656     LineSectionSize += Offset - OffsetBeforeLEBs;
 657   }
 658   Asm->emitInt8(0);
 659   LineSectionSize += 1;
 660
 661   Asm->OutStreamer->EmitLabel(HeaderEndLabel);
 662
 663   // Copy the actual line table program over.
 664   Asm->OutStreamer->EmitBytes(Contents.slice(Offset, UnitEnd));
 665   LineSectionSize += UnitEnd - Offset;
 666
 667   Asm->OutStreamer->EmitLabel(EndLabel);
 668   Offset = UnitEnd;
 669 }
 670
 671 static void emitSectionContents(const object::ObjectFile &Obj,
 672                                 StringRef SecName, MCStreamer *MS) {
 673   if (auto Sec = getSectionByName(Obj, SecName)) {
 674     if (Expected<StringRef> E = Sec->getContents())
 675       MS->EmitBytes(*E);
 676     else
 677       consumeError(E.takeError());
 678   }
 679 }
 680
 681 void DwarfStreamer::copyInvariantDebugSection(const object::ObjectFile &Obj) {
 682   if (!Options.Translator) {
 683     MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection());
 684     emitSectionContents(Obj, "debug_line", MS);
 685   }
 686
 687   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLocSection());
 688   emitSectionContents(Obj, "debug_loc", MS);
 689
 690   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
 691   emitSectionContents(Obj, "debug_ranges", MS);
 692
 693   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());
 694   emitSectionContents(Obj, "debug_frame", MS);
 695
 696   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfARangesSection());
 697   emitSectionContents(Obj, "debug_aranges", MS);
 698 }
 699
 700 /// Emit the pubnames or pubtypes section contribution for \p
 701 /// Unit into \p Sec. The data is provided in \p Names.
 702 void DwarfStreamer::emitPubSectionForUnit(
 703     MCSection *Sec, StringRef SecName, const CompileUnit &Unit,
 704     const std::vector<CompileUnit::AccelInfo> &Names) {
 705   if (Names.empty())
 706     return;
 707
 708   // Start the dwarf pubnames section.
 709   Asm->OutStreamer->SwitchSection(Sec);
 710   MCSymbol *BeginLabel = Asm->createTempSymbol("pub" + SecName + "_begin");
 711   MCSymbol *EndLabel = Asm->createTempSymbol("pub" + SecName + "_end");
 712
 713   bool HeaderEmitted = false;
 714   // Emit the pubnames for this compilation unit.
 715   for (const auto &Name : Names) {
 716     if (Name.SkipPubSection)
 717       continue;
 718
 719     if (!HeaderEmitted) {
 720       // Emit the header.
 721       Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Length
 722       Asm->OutStreamer->EmitLabel(BeginLabel);
 723       Asm->emitInt16(dwarf::DW_PUBNAMES_VERSION); // Version
 724       Asm->emitInt32(Unit.getStartOffset());      // Unit offset
 725       Asm->emitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset()); // Size
 726       HeaderEmitted = true;
 727     }
 728     Asm->emitInt32(Name.Die->getOffset());
 729
 730     // Emit the string itself.
 731     Asm->OutStreamer->EmitBytes(Name.Name.getString());
 732     // Emit a null terminator.
 733     Asm->emitInt8(0);
 734   }
 735
 736   if (!HeaderEmitted)
 737     return;
 738   Asm->emitInt32(0); // End marker.
 739   Asm->OutStreamer->EmitLabel(EndLabel);
 740 }
 741
 742 /// Emit .debug_pubnames for \p Unit.
 743 void DwarfStreamer::emitPubNamesForUnit(const CompileUnit &Unit) {
 744   emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubNamesSection(),
 745                         "names", Unit, Unit.getPubnames());
 746 }
 747
 748 /// Emit .debug_pubtypes for \p Unit.
 749 void DwarfStreamer::emitPubTypesForUnit(const CompileUnit &Unit) {
 750   emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubTypesSection(),
 751                         "types", Unit, Unit.getPubtypes());
 752 }
 753
 754 /// Emit a CIE into the debug_frame section.
 755 void DwarfStreamer::emitCIE(StringRef CIEBytes) {
 756   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());
 757
 758   MS->EmitBytes(CIEBytes);
 759   FrameSectionSize += CIEBytes.size();
 760 }
 761
 762 /// Emit a FDE into the debug_frame section. \p FDEBytes
 763 /// contains the FDE data without the length, CIE offset and address
 764 /// which will be replaced with the parameter values.
 765 void DwarfStreamer::emitFDE(uint32_t CIEOffset, uint32_t AddrSize,
 766                             uint32_t Address, StringRef FDEBytes) {
 767   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfFrameSection());
 768
 769   MS->EmitIntValue(FDEBytes.size() + 4 + AddrSize, 4);
 770   MS->EmitIntValue(CIEOffset, 4);
 771   MS->EmitIntValue(Address, AddrSize);
 772   MS->EmitBytes(FDEBytes);
 773   FrameSectionSize += FDEBytes.size() + 8 + AddrSize;
 774 }
 775
 776 } // namespace dsymutil
 777 } // namespace llvm