llvm/lib/DWP/DWP.cpp

   1 //===-- llvm-dwp.cpp - Split DWARF merging tool for llvm ------------------===//
   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 // A utility for merging DWARF 5 Split DWARF .dwo files into .dwp (DWARF
  10 // package files).
  11 //
  12 //===----------------------------------------------------------------------===//
  13 #include "llvm/DWP/DWP.h"
  14 #include "llvm/DWP/DWPError.h"
  15 #include "llvm/MC/MCContext.h"
  16 #include "llvm/MC/MCObjectFileInfo.h"
  17 #include "llvm/MC/MCTargetOptionsCommandFlags.h"
  18 #include "llvm/Object/Decompressor.h"
  19
  20 using namespace llvm;
  21 using namespace llvm::object;
  22
  23 static mc::RegisterMCTargetOptionsFlags MCTargetOptionsFlags;
  24
  25 // Returns the size of debug_str_offsets section headers in bytes.
  26 static uint64_t debugStrOffsetsHeaderSize(DataExtractor StrOffsetsData,
  27                                           uint16_t DwarfVersion) {
  28   if (DwarfVersion <= 4)
  29     return 0; // There is no header before dwarf 5.
  30   uint64_t Offset = 0;
  31   uint64_t Length = StrOffsetsData.getU32(&Offset);
  32   if (Length == llvm::dwarf::DW_LENGTH_DWARF64)
  33     return 16; // unit length: 12 bytes, version: 2 bytes, padding: 2 bytes.
  34   return 8;    // unit length: 4 bytes, version: 2 bytes, padding: 2 bytes.
  35 }
  36
  37 static uint64_t getCUAbbrev(StringRef Abbrev, uint64_t AbbrCode) {
  38   uint64_t Offset = 0;
  39   DataExtractor AbbrevData(Abbrev, true, 0);
  40   while (AbbrevData.getULEB128(&Offset) != AbbrCode) {
  41     // Tag
  42     AbbrevData.getULEB128(&Offset);
  43     // DW_CHILDREN
  44     AbbrevData.getU8(&Offset);
  45     // Attributes
  46     while (AbbrevData.getULEB128(&Offset) | AbbrevData.getULEB128(&Offset))
  47       ;
  48   }
  49   return Offset;
  50 }
  51
  52 static Expected<const char *>
  53 getIndexedString(dwarf::Form Form, DataExtractor InfoData, uint64_t &InfoOffset,
  54                  StringRef StrOffsets, StringRef Str, uint16_t Version) {
  55   if (Form == dwarf::DW_FORM_string)
  56     return InfoData.getCStr(&InfoOffset);
  57   uint64_t StrIndex;
  58   switch (Form) {
  59   case dwarf::DW_FORM_strx1:
  60     StrIndex = InfoData.getU8(&InfoOffset);
  61     break;
  62   case dwarf::DW_FORM_strx2:
  63     StrIndex = InfoData.getU16(&InfoOffset);
  64     break;
  65   case dwarf::DW_FORM_strx3:
  66     StrIndex = InfoData.getU24(&InfoOffset);
  67     break;
  68   case dwarf::DW_FORM_strx4:
  69     StrIndex = InfoData.getU32(&InfoOffset);
  70     break;
  71   case dwarf::DW_FORM_strx:
  72   case dwarf::DW_FORM_GNU_str_index:
  73     StrIndex = InfoData.getULEB128(&InfoOffset);
  74     break;
  75   default:
  76     return make_error<DWPError>(
  77         "string field must be encoded with one of the following: "
  78         "DW_FORM_string, DW_FORM_strx, DW_FORM_strx1, DW_FORM_strx2, "
  79         "DW_FORM_strx3, DW_FORM_strx4, or DW_FORM_GNU_str_index.");
  80   }
  81   DataExtractor StrOffsetsData(StrOffsets, true, 0);
  82   uint64_t StrOffsetsOffset = 4 * StrIndex;
  83   StrOffsetsOffset += debugStrOffsetsHeaderSize(StrOffsetsData, Version);
  84
  85   uint64_t StrOffset = StrOffsetsData.getU32(&StrOffsetsOffset);
  86   DataExtractor StrData(Str, true, 0);
  87   return StrData.getCStr(&StrOffset);
  88 }
  89
  90 static Expected<CompileUnitIdentifiers>
  91 getCUIdentifiers(InfoSectionUnitHeader &Header, StringRef Abbrev,
  92                  StringRef Info, StringRef StrOffsets, StringRef Str) {
  93   DataExtractor InfoData(Info, true, 0);
  94   uint64_t Offset = Header.HeaderSize;
  95   if (Header.Version >= 5 && Header.UnitType != dwarf::DW_UT_split_compile)
  96     return make_error<DWPError>(
  97         std::string("unit type DW_UT_split_compile type not found in "
  98                     "debug_info header. Unexpected unit type 0x" +
  99                     utostr(Header.UnitType) + " found"));
 100
 101   CompileUnitIdentifiers ID;
 102
 103   uint32_t AbbrCode = InfoData.getULEB128(&Offset);
 104   DataExtractor AbbrevData(Abbrev, true, 0);
 105   uint64_t AbbrevOffset = getCUAbbrev(Abbrev, AbbrCode);
 106   auto Tag = static_cast<dwarf::Tag>(AbbrevData.getULEB128(&AbbrevOffset));
 107   if (Tag != dwarf::DW_TAG_compile_unit)
 108     return make_error<DWPError>("top level DIE is not a compile unit");
 109   // DW_CHILDREN
 110   AbbrevData.getU8(&AbbrevOffset);
 111   uint32_t Name;
 112   dwarf::Form Form;
 113   while ((Name = AbbrevData.getULEB128(&AbbrevOffset)) |
 114              (Form = static_cast<dwarf::Form>(
 115                   AbbrevData.getULEB128(&AbbrevOffset))) &&
 116          (Name != 0 || Form != 0)) {
 117     switch (Name) {
 118     case dwarf::DW_AT_name: {
 119       Expected<const char *> EName = getIndexedString(
 120           Form, InfoData, Offset, StrOffsets, Str, Header.Version);
 121       if (!EName)
 122         return EName.takeError();
 123       ID.Name = *EName;
 124       break;
 125     }
 126     case dwarf::DW_AT_GNU_dwo_name:
 127     case dwarf::DW_AT_dwo_name: {
 128       Expected<const char *> EName = getIndexedString(
 129           Form, InfoData, Offset, StrOffsets, Str, Header.Version);
 130       if (!EName)
 131         return EName.takeError();
 132       ID.DWOName = *EName;
 133       break;
 134     }
 135     case dwarf::DW_AT_GNU_dwo_id:
 136       Header.Signature = InfoData.getU64(&Offset);
 137       break;
 138     default:
 139       DWARFFormValue::skipValue(
 140           Form, InfoData, &Offset,
 141           dwarf::FormParams({Header.Version, Header.AddrSize, Header.Format}));
 142     }
 143   }
 144   if (!Header.Signature)
 145     return make_error<DWPError>("compile unit missing dwo_id");
 146   ID.Signature = *Header.Signature;
 147   return ID;
 148 }
 149
 150 static bool isSupportedSectionKind(DWARFSectionKind Kind) {
 151   return Kind != DW_SECT_EXT_unknown;
 152 }
 153
 154 namespace llvm {
 155 // Convert an internal section identifier into the index to use with
 156 // UnitIndexEntry::Contributions.
 157 unsigned getContributionIndex(DWARFSectionKind Kind, uint32_t IndexVersion) {
 158   assert(serializeSectionKind(Kind, IndexVersion) >= DW_SECT_INFO);
 159   return serializeSectionKind(Kind, IndexVersion) - DW_SECT_INFO;
 160 }
 161 } // namespace llvm
 162
 163 // Convert a UnitIndexEntry::Contributions index to the corresponding on-disk
 164 // value of the section identifier.
 165 static unsigned getOnDiskSectionId(unsigned Index) {
 166   return Index + DW_SECT_INFO;
 167 }
 168
 169 static StringRef getSubsection(StringRef Section,
 170                                const DWARFUnitIndex::Entry &Entry,
 171                                DWARFSectionKind Kind) {
 172   const auto *Off = Entry.getContribution(Kind);
 173   if (!Off)
 174     return StringRef();
 175   return Section.substr(Off->Offset, Off->Length);
 176 }
 177
 178 static void
 179 addAllTypesFromDWP(MCStreamer &Out,
 180                    MapVector<uint64_t, UnitIndexEntry> &TypeIndexEntries,
 181                    const DWARFUnitIndex &TUIndex, MCSection *OutputTypes,
 182                    StringRef Types, const UnitIndexEntry &TUEntry,
 183                    uint32_t &TypesOffset, unsigned TypesContributionIndex) {
 184   Out.SwitchSection(OutputTypes);
 185   for (const DWARFUnitIndex::Entry &E : TUIndex.getRows()) {
 186     auto *I = E.getContributions();
 187     if (!I)
 188       continue;
 189     auto P = TypeIndexEntries.insert(std::make_pair(E.getSignature(), TUEntry));
 190     if (!P.second)
 191       continue;
 192     auto &Entry = P.first->second;
 193     // Zero out the debug_info contribution
 194     Entry.Contributions[0] = {};
 195     for (auto Kind : TUIndex.getColumnKinds()) {
 196       if (!isSupportedSectionKind(Kind))
 197         continue;
 198       auto &C =
 199           Entry.Contributions[getContributionIndex(Kind, TUIndex.getVersion())];
 200       C.Offset += I->Offset;
 201       C.Length = I->Length;
 202       ++I;
 203     }
 204     auto &C = Entry.Contributions[TypesContributionIndex];
 205     Out.emitBytes(Types.substr(
 206         C.Offset - TUEntry.Contributions[TypesContributionIndex].Offset,
 207         C.Length));
 208     C.Offset = TypesOffset;
 209     TypesOffset += C.Length;
 210   }
 211 }
 212
 213 static void addAllTypesFromTypesSection(
 214     MCStreamer &Out, MapVector<uint64_t, UnitIndexEntry> &TypeIndexEntries,
 215     MCSection *OutputTypes, const std::vector<StringRef> &TypesSections,
 216     const UnitIndexEntry &CUEntry, uint32_t &TypesOffset) {
 217   for (StringRef Types : TypesSections) {
 218     Out.SwitchSection(OutputTypes);
 219     uint64_t Offset = 0;
 220     DataExtractor Data(Types, true, 0);
 221     while (Data.isValidOffset(Offset)) {
 222       UnitIndexEntry Entry = CUEntry;
 223       // Zero out the debug_info contribution
 224       Entry.Contributions[0] = {};
 225       auto &C = Entry.Contributions[getContributionIndex(DW_SECT_EXT_TYPES, 2)];
 226       C.Offset = TypesOffset;
 227       auto PrevOffset = Offset;
 228       // Length of the unit, including the 4 byte length field.
 229       C.Length = Data.getU32(&Offset) + 4;
 230
 231       Data.getU16(&Offset); // Version
 232       Data.getU32(&Offset); // Abbrev offset
 233       Data.getU8(&Offset);  // Address size
 234       auto Signature = Data.getU64(&Offset);
 235       Offset = PrevOffset + C.Length;
 236
 237       auto P = TypeIndexEntries.insert(std::make_pair(Signature, Entry));
 238       if (!P.second)
 239         continue;
 240
 241       Out.emitBytes(Types.substr(PrevOffset, C.Length));
 242       TypesOffset += C.Length;
 243     }
 244   }
 245 }
 246
 247 static std::string buildDWODescription(StringRef Name, StringRef DWPName,
 248                                        StringRef DWOName) {
 249   std::string Text = "\'";
 250   Text += Name;
 251   Text += '\'';
 252   if (!DWPName.empty()) {
 253     Text += " (from ";
 254     if (!DWOName.empty()) {
 255       Text += '\'';
 256       Text += DWOName;
 257       Text += "' in ";
 258     }
 259     Text += '\'';
 260     Text += DWPName;
 261     Text += "')";
 262   }
 263   return Text;
 264 }
 265
 266 static Error createError(StringRef Name, Error E) {
 267   return make_error<DWPError>(
 268       ("failure while decompressing compressed section: '" + Name + "', " +
 269        llvm::toString(std::move(E)))
 270           .str());
 271 }
 272
 273 static Error
 274 handleCompressedSection(std::deque<SmallString<32>> &UncompressedSections,
 275                         StringRef &Name, StringRef &Contents) {
 276   if (!Decompressor::isGnuStyle(Name))
 277     return Error::success();
 278
 279   Expected<Decompressor> Dec =
 280       Decompressor::create(Name, Contents, false /*IsLE*/, false /*Is64Bit*/);
 281   if (!Dec)
 282     return createError(Name, Dec.takeError());
 283
 284   UncompressedSections.emplace_back();
 285   if (Error E = Dec->resizeAndDecompress(UncompressedSections.back()))
 286     return createError(Name, std::move(E));
 287
 288   Name = Name.substr(2); // Drop ".z"
 289   Contents = UncompressedSections.back();
 290   return Error::success();
 291 }
 292
 293 namespace llvm {
 294 // Parse and return the header of an info section compile/type unit.
 295 Expected<InfoSectionUnitHeader> parseInfoSectionUnitHeader(StringRef Info) {
 296   InfoSectionUnitHeader Header;
 297   Error Err = Error::success();
 298   uint64_t Offset = 0;
 299   DWARFDataExtractor InfoData(Info, true, 0);
 300   std::tie(Header.Length, Header.Format) =
 301       InfoData.getInitialLength(&Offset, &Err);
 302   if (Err)
 303     return make_error<DWPError>("cannot parse compile unit length: " +
 304                                 llvm::toString(std::move(Err)));
 305
 306   if (!InfoData.isValidOffset(Offset + (Header.Length - 1))) {
 307     return make_error<DWPError>(
 308         "compile unit exceeds .debug_info section range: " +
 309         utostr(Offset + Header.Length) + " >= " + utostr(InfoData.size()));
 310   }
 311
 312   Header.Version = InfoData.getU16(&Offset, &Err);
 313   if (Err)
 314     return make_error<DWPError>("cannot parse compile unit version: " +
 315                                 llvm::toString(std::move(Err)));
 316
 317   uint64_t MinHeaderLength;
 318   if (Header.Version >= 5) {
 319     // Size: Version (2), UnitType (1), AddrSize (1), DebugAbbrevOffset (4),
 320     // Signature (8)
 321     MinHeaderLength = 16;
 322   } else {
 323     // Size: Version (2), DebugAbbrevOffset (4), AddrSize (1)
 324     MinHeaderLength = 7;
 325   }
 326   if (Header.Length < MinHeaderLength) {
 327     return make_error<DWPError>("unit length is too small: expected at least " +
 328                                 utostr(MinHeaderLength) + " got " +
 329                                 utostr(Header.Length) + ".");
 330   }
 331   if (Header.Version >= 5) {
 332     Header.UnitType = InfoData.getU8(&Offset);
 333     Header.AddrSize = InfoData.getU8(&Offset);
 334     Header.DebugAbbrevOffset = InfoData.getU32(&Offset);
 335     Header.Signature = InfoData.getU64(&Offset);
 336     if (Header.UnitType == dwarf::DW_UT_split_type) {
 337       // Type offset.
 338       MinHeaderLength += 4;
 339       if (Header.Length < MinHeaderLength)
 340         return make_error<DWPError>("type unit is missing type offset");
 341       InfoData.getU32(&Offset);
 342     }
 343   } else {
 344     // Note that, address_size and debug_abbrev_offset fields have switched
 345     // places between dwarf version 4 and 5.
 346     Header.DebugAbbrevOffset = InfoData.getU32(&Offset);
 347     Header.AddrSize = InfoData.getU8(&Offset);
 348   }
 349
 350   Header.HeaderSize = Offset;
 351   return Header;
 352 }
 353
 354 void writeStringsAndOffsets(MCStreamer &Out, DWPStringPool &Strings,
 355                             MCSection *StrOffsetSection,
 356                             StringRef CurStrSection,
 357                             StringRef CurStrOffsetSection, uint16_t Version) {
 358   // Could possibly produce an error or warning if one of these was non-null but
 359   // the other was null.
 360   if (CurStrSection.empty() || CurStrOffsetSection.empty())
 361     return;
 362
 363   DenseMap<uint64_t, uint32_t> OffsetRemapping;
 364
 365   DataExtractor Data(CurStrSection, true, 0);
 366   uint64_t LocalOffset = 0;
 367   uint64_t PrevOffset = 0;
 368   while (const char *S = Data.getCStr(&LocalOffset)) {
 369     OffsetRemapping[PrevOffset] =
 370         Strings.getOffset(S, LocalOffset - PrevOffset);
 371     PrevOffset = LocalOffset;
 372   }
 373
 374   Data = DataExtractor(CurStrOffsetSection, true, 0);
 375
 376   Out.SwitchSection(StrOffsetSection);
 377
 378   uint64_t HeaderSize = debugStrOffsetsHeaderSize(Data, Version);
 379   uint64_t Offset = 0;
 380   uint64_t Size = CurStrOffsetSection.size();
 381   // FIXME: This can be caused by bad input and should be handled as such.
 382   assert(HeaderSize <= Size && "StrOffsetSection size is less than its header");
 383   // Copy the header to the output.
 384   Out.emitBytes(Data.getBytes(&Offset, HeaderSize));
 385   while (Offset < Size) {
 386     auto OldOffset = Data.getU32(&Offset);
 387     auto NewOffset = OffsetRemapping[OldOffset];
 388     Out.emitIntValue(NewOffset, 4);
 389   }
 390 }
 391
 392 void writeIndexTable(
 393     MCStreamer &Out, ArrayRef<unsigned> ContributionOffsets,
 394     const MapVector<uint64_t, UnitIndexEntry> &IndexEntries,
 395     uint32_t DWARFUnitIndex::Entry::SectionContribution::*Field) {
 396   for (const auto &E : IndexEntries)
 397     for (size_t I = 0; I != array_lengthof(E.second.Contributions); ++I)
 398       if (ContributionOffsets[I])
 399         Out.emitIntValue(E.second.Contributions[I].*Field, 4);
 400 }
 401
 402 void writeIndex(MCStreamer &Out, MCSection *Section,
 403                 ArrayRef<unsigned> ContributionOffsets,
 404                 const MapVector<uint64_t, UnitIndexEntry> &IndexEntries,
 405                 uint32_t IndexVersion) {
 406   if (IndexEntries.empty())
 407     return;
 408
 409   unsigned Columns = 0;
 410   for (auto &C : ContributionOffsets)
 411     if (C)
 412       ++Columns;
 413
 414   std::vector<unsigned> Buckets(NextPowerOf2(3 * IndexEntries.size() / 2));
 415   uint64_t Mask = Buckets.size() - 1;
 416   size_t I = 0;
 417   for (const auto &P : IndexEntries) {
 418     auto S = P.first;
 419     auto H = S & Mask;
 420     auto HP = ((S >> 32) & Mask) | 1;
 421     while (Buckets[H]) {
 422       assert(S != IndexEntries.begin()[Buckets[H] - 1].first &&
 423              "Duplicate unit");
 424       H = (H + HP) & Mask;
 425     }
 426     Buckets[H] = I + 1;
 427     ++I;
 428   }
 429
 430   Out.SwitchSection(Section);
 431   Out.emitIntValue(IndexVersion, 4);        // Version
 432   Out.emitIntValue(Columns, 4);             // Columns
 433   Out.emitIntValue(IndexEntries.size(), 4); // Num Units
 434   Out.emitIntValue(Buckets.size(), 4);      // Num Buckets
 435
 436   // Write the signatures.
 437   for (const auto &I : Buckets)
 438     Out.emitIntValue(I ? IndexEntries.begin()[I - 1].first : 0, 8);
 439
 440   // Write the indexes.
 441   for (const auto &I : Buckets)
 442     Out.emitIntValue(I, 4);
 443
 444   // Write the column headers (which sections will appear in the table)
 445   for (size_t I = 0; I != ContributionOffsets.size(); ++I)
 446     if (ContributionOffsets[I])
 447       Out.emitIntValue(getOnDiskSectionId(I), 4);
 448
 449   // Write the offsets.
 450   writeIndexTable(Out, ContributionOffsets, IndexEntries,
 451                   &DWARFUnitIndex::Entry::SectionContribution::Offset);
 452
 453   // Write the lengths.
 454   writeIndexTable(Out, ContributionOffsets, IndexEntries,
 455                   &DWARFUnitIndex::Entry::SectionContribution::Length);
 456 }
 457
 458 Error buildDuplicateError(const std::pair<uint64_t, UnitIndexEntry> &PrevE,
 459                           const CompileUnitIdentifiers &ID, StringRef DWPName) {
 460   return make_error<DWPError>(
 461       std::string("duplicate DWO ID (") + utohexstr(PrevE.first) + ") in " +
 462       buildDWODescription(PrevE.second.Name, PrevE.second.DWPName,
 463                           PrevE.second.DWOName) +
 464       " and " + buildDWODescription(ID.Name, DWPName, ID.DWOName));
 465 }
 466
 467 Error handleSection(
 468     const StringMap<std::pair<MCSection *, DWARFSectionKind>> &KnownSections,
 469     const MCSection *StrSection, const MCSection *StrOffsetSection,
 470     const MCSection *TypesSection, const MCSection *CUIndexSection,
 471     const MCSection *TUIndexSection, const MCSection *InfoSection,
 472     const SectionRef &Section, MCStreamer &Out,
 473     std::deque<SmallString<32>> &UncompressedSections,
 474     uint32_t (&ContributionOffsets)[8], UnitIndexEntry &CurEntry,
 475     StringRef &CurStrSection, StringRef &CurStrOffsetSection,
 476     std::vector<StringRef> &CurTypesSection,
 477     std::vector<StringRef> &CurInfoSection, StringRef &AbbrevSection,
 478     StringRef &CurCUIndexSection, StringRef &CurTUIndexSection,
 479     std::vector<std::pair<DWARFSectionKind, uint32_t>> &SectionLength) {
 480   if (Section.isBSS())
 481     return Error::success();
 482
 483   if (Section.isVirtual())
 484     return Error::success();
 485
 486   Expected<StringRef> NameOrErr = Section.getName();
 487   if (!NameOrErr)
 488     return NameOrErr.takeError();
 489   StringRef Name = *NameOrErr;
 490
 491   Expected<StringRef> ContentsOrErr = Section.getContents();
 492   if (!ContentsOrErr)
 493     return ContentsOrErr.takeError();
 494   StringRef Contents = *ContentsOrErr;
 495
 496   if (auto Err = handleCompressedSection(UncompressedSections, Name, Contents))
 497     return Err;
 498
 499   Name = Name.substr(Name.find_first_not_of("._"));
 500
 501   auto SectionPair = KnownSections.find(Name);
 502   if (SectionPair == KnownSections.end())
 503     return Error::success();
 504
 505   if (DWARFSectionKind Kind = SectionPair->second.second) {
 506     if (Kind != DW_SECT_EXT_TYPES && Kind != DW_SECT_INFO) {
 507       SectionLength.push_back(std::make_pair(Kind, Contents.size()));
 508     }
 509
 510     if (Kind == DW_SECT_ABBREV) {
 511       AbbrevSection = Contents;
 512     }
 513   }
 514
 515   MCSection *OutSection = SectionPair->second.first;
 516   if (OutSection == StrOffsetSection)
 517     CurStrOffsetSection = Contents;
 518   else if (OutSection == StrSection)
 519     CurStrSection = Contents;
 520   else if (OutSection == TypesSection)
 521     CurTypesSection.push_back(Contents);
 522   else if (OutSection == CUIndexSection)
 523     CurCUIndexSection = Contents;
 524   else if (OutSection == TUIndexSection)
 525     CurTUIndexSection = Contents;
 526   else if (OutSection == InfoSection)
 527     CurInfoSection.push_back(Contents);
 528   else {
 529     Out.SwitchSection(OutSection);
 530     Out.emitBytes(Contents);
 531   }
 532   return Error::success();
 533 }
 534
 535 Error write(MCStreamer &Out, ArrayRef<std::string> Inputs) {
 536   const auto &MCOFI = *Out.getContext().getObjectFileInfo();
 537   MCSection *const StrSection = MCOFI.getDwarfStrDWOSection();
 538   MCSection *const StrOffsetSection = MCOFI.getDwarfStrOffDWOSection();
 539   MCSection *const TypesSection = MCOFI.getDwarfTypesDWOSection();
 540   MCSection *const CUIndexSection = MCOFI.getDwarfCUIndexSection();
 541   MCSection *const TUIndexSection = MCOFI.getDwarfTUIndexSection();
 542   MCSection *const InfoSection = MCOFI.getDwarfInfoDWOSection();
 543   const StringMap<std::pair<MCSection *, DWARFSectionKind>> KnownSections = {
 544       {"debug_info.dwo", {InfoSection, DW_SECT_INFO}},
 545       {"debug_types.dwo", {MCOFI.getDwarfTypesDWOSection(), DW_SECT_EXT_TYPES}},
 546       {"debug_str_offsets.dwo", {StrOffsetSection, DW_SECT_STR_OFFSETS}},
 547       {"debug_str.dwo", {StrSection, static_cast<DWARFSectionKind>(0)}},
 548       {"debug_loc.dwo", {MCOFI.getDwarfLocDWOSection(), DW_SECT_EXT_LOC}},
 549       {"debug_line.dwo", {MCOFI.getDwarfLineDWOSection(), DW_SECT_LINE}},
 550       {"debug_macro.dwo", {MCOFI.getDwarfMacroDWOSection(), DW_SECT_MACRO}},
 551       {"debug_abbrev.dwo", {MCOFI.getDwarfAbbrevDWOSection(), DW_SECT_ABBREV}},
 552       {"debug_loclists.dwo",
 553        {MCOFI.getDwarfLoclistsDWOSection(), DW_SECT_LOCLISTS}},
 554       {"debug_rnglists.dwo",
 555        {MCOFI.getDwarfRnglistsDWOSection(), DW_SECT_RNGLISTS}},
 556       {"debug_cu_index", {CUIndexSection, static_cast<DWARFSectionKind>(0)}},
 557       {"debug_tu_index", {TUIndexSection, static_cast<DWARFSectionKind>(0)}}};
 558
 559   MapVector<uint64_t, UnitIndexEntry> IndexEntries;
 560   MapVector<uint64_t, UnitIndexEntry> TypeIndexEntries;
 561
 562   uint32_t ContributionOffsets[8] = {};
 563   uint16_t Version = 0;
 564   uint32_t IndexVersion = 0;
 565
 566   DWPStringPool Strings(Out, StrSection);
 567
 568   SmallVector<OwningBinary<object::ObjectFile>, 128> Objects;
 569   Objects.reserve(Inputs.size());
 570
 571   std::deque<SmallString<32>> UncompressedSections;
 572
 573   for (const auto &Input : Inputs) {
 574     auto ErrOrObj = object::ObjectFile::createObjectFile(Input);
 575     if (!ErrOrObj)
 576       return ErrOrObj.takeError();
 577
 578     auto &Obj = *ErrOrObj->getBinary();
 579     Objects.push_back(std::move(*ErrOrObj));
 580
 581     UnitIndexEntry CurEntry = {};
 582
 583     StringRef CurStrSection;
 584     StringRef CurStrOffsetSection;
 585     std::vector<StringRef> CurTypesSection;
 586     std::vector<StringRef> CurInfoSection;
 587     StringRef AbbrevSection;
 588     StringRef CurCUIndexSection;
 589     StringRef CurTUIndexSection;
 590
 591     // This maps each section contained in this file to its length.
 592     // This information is later on used to calculate the contributions,
 593     // i.e. offset and length, of each compile/type unit to a section.
 594     std::vector<std::pair<DWARFSectionKind, uint32_t>> SectionLength;
 595
 596     for (const auto &Section : Obj.sections())
 597       if (auto Err = handleSection(
 598               KnownSections, StrSection, StrOffsetSection, TypesSection,
 599               CUIndexSection, TUIndexSection, InfoSection, Section, Out,
 600               UncompressedSections, ContributionOffsets, CurEntry,
 601               CurStrSection, CurStrOffsetSection, CurTypesSection,
 602               CurInfoSection, AbbrevSection, CurCUIndexSection,
 603               CurTUIndexSection, SectionLength))
 604         return Err;
 605
 606     if (CurInfoSection.empty())
 607       continue;
 608
 609     Expected<InfoSectionUnitHeader> HeaderOrErr =
 610         parseInfoSectionUnitHeader(CurInfoSection.front());
 611     if (!HeaderOrErr)
 612       return HeaderOrErr.takeError();
 613     InfoSectionUnitHeader &Header = *HeaderOrErr;
 614
 615     if (Version == 0) {
 616       Version = Header.Version;
 617       IndexVersion = Version < 5 ? 2 : 5;
 618     } else if (Version != Header.Version) {
 619       return make_error<DWPError>("incompatible DWARF compile unit versions.");
 620     }
 621
 622     writeStringsAndOffsets(Out, Strings, StrOffsetSection, CurStrSection,
 623                            CurStrOffsetSection, Header.Version);
 624
 625     for (auto Pair : SectionLength) {
 626       auto Index = getContributionIndex(Pair.first, IndexVersion);
 627       CurEntry.Contributions[Index].Offset = ContributionOffsets[Index];
 628       ContributionOffsets[Index] +=
 629           (CurEntry.Contributions[Index].Length = Pair.second);
 630     }
 631
 632     uint32_t &InfoSectionOffset =
 633         ContributionOffsets[getContributionIndex(DW_SECT_INFO, IndexVersion)];
 634     if (CurCUIndexSection.empty()) {
 635       bool FoundCUUnit = false;
 636       Out.SwitchSection(InfoSection);
 637       for (StringRef Info : CurInfoSection) {
 638         uint64_t UnitOffset = 0;
 639         while (Info.size() > UnitOffset) {
 640           Expected<InfoSectionUnitHeader> HeaderOrError =
 641               parseInfoSectionUnitHeader(Info.substr(UnitOffset, Info.size()));
 642           if (!HeaderOrError)
 643             return HeaderOrError.takeError();
 644           InfoSectionUnitHeader &Header = *HeaderOrError;
 645
 646           UnitIndexEntry Entry = CurEntry;
 647           auto &C = Entry.Contributions[getContributionIndex(DW_SECT_INFO,
 648                                                              IndexVersion)];
 649           C.Offset = InfoSectionOffset;
 650           C.Length = Header.Length + 4;
 651           UnitOffset += C.Length;
 652           if (Header.Version < 5 ||
 653               Header.UnitType == dwarf::DW_UT_split_compile) {
 654             Expected<CompileUnitIdentifiers> EID =
 655                 getCUIdentifiers(Header, AbbrevSection,
 656                                  Info.substr(UnitOffset - C.Length, C.Length),
 657                                  CurStrOffsetSection, CurStrSection);
 658
 659             if (!EID)
 660               return createFileError(Input, EID.takeError());
 661             const auto &ID = *EID;
 662             auto P = IndexEntries.insert(std::make_pair(ID.Signature, Entry));
 663             if (!P.second)
 664               return buildDuplicateError(*P.first, ID, "");
 665             P.first->second.Name = ID.Name;
 666             P.first->second.DWOName = ID.DWOName;
 667
 668             FoundCUUnit = true;
 669           } else if (Header.UnitType == dwarf::DW_UT_split_type) {
 670             auto P = TypeIndexEntries.insert(
 671                 std::make_pair(Header.Signature.getValue(), Entry));
 672             if (!P.second)
 673               continue;
 674           }
 675           Out.emitBytes(Info.substr(UnitOffset - C.Length, C.Length));
 676           InfoSectionOffset += C.Length;
 677         }
 678       }
 679
 680       if (!FoundCUUnit)
 681         return make_error<DWPError>("no compile unit found in file: " + Input);
 682
 683       if (IndexVersion == 2) {
 684         // Add types from the .debug_types section from DWARF < 5.
 685         addAllTypesFromTypesSection(
 686             Out, TypeIndexEntries, TypesSection, CurTypesSection, CurEntry,
 687             ContributionOffsets[getContributionIndex(DW_SECT_EXT_TYPES, 2)]);
 688       }
 689       continue;
 690     }
 691
 692     if (CurInfoSection.size() != 1)
 693       return make_error<DWPError>("expected exactly one occurrence of a debug "
 694                                   "info section in a .dwp file");
 695     StringRef DwpSingleInfoSection = CurInfoSection.front();
 696
 697     DWARFUnitIndex CUIndex(DW_SECT_INFO);
 698     DataExtractor CUIndexData(CurCUIndexSection, Obj.isLittleEndian(), 0);
 699     if (!CUIndex.parse(CUIndexData))
 700       return make_error<DWPError>("failed to parse cu_index");
 701     if (CUIndex.getVersion() != IndexVersion)
 702       return make_error<DWPError>("incompatible cu_index versions, found " +
 703                                   utostr(CUIndex.getVersion()) +
 704                                   " and expecting " + utostr(IndexVersion));
 705
 706     Out.SwitchSection(InfoSection);
 707     for (const DWARFUnitIndex::Entry &E : CUIndex.getRows()) {
 708       auto *I = E.getContributions();
 709       if (!I)
 710         continue;
 711       auto P = IndexEntries.insert(std::make_pair(E.getSignature(), CurEntry));
 712       StringRef CUInfoSection =
 713           getSubsection(DwpSingleInfoSection, E, DW_SECT_INFO);
 714       Expected<InfoSectionUnitHeader> HeaderOrError =
 715           parseInfoSectionUnitHeader(CUInfoSection);
 716       if (!HeaderOrError)
 717         return HeaderOrError.takeError();
 718       InfoSectionUnitHeader &Header = *HeaderOrError;
 719
 720       Expected<CompileUnitIdentifiers> EID = getCUIdentifiers(
 721           Header, getSubsection(AbbrevSection, E, DW_SECT_ABBREV),
 722           CUInfoSection,
 723           getSubsection(CurStrOffsetSection, E, DW_SECT_STR_OFFSETS),
 724           CurStrSection);
 725       if (!EID)
 726         return createFileError(Input, EID.takeError());
 727       const auto &ID = *EID;
 728       if (!P.second)
 729         return buildDuplicateError(*P.first, ID, Input);
 730       auto &NewEntry = P.first->second;
 731       NewEntry.Name = ID.Name;
 732       NewEntry.DWOName = ID.DWOName;
 733       NewEntry.DWPName = Input;
 734       for (auto Kind : CUIndex.getColumnKinds()) {
 735         if (!isSupportedSectionKind(Kind))
 736           continue;
 737         auto &C =
 738             NewEntry.Contributions[getContributionIndex(Kind, IndexVersion)];
 739         C.Offset += I->Offset;
 740         C.Length = I->Length;
 741         ++I;
 742       }
 743       unsigned Index = getContributionIndex(DW_SECT_INFO, IndexVersion);
 744       auto &C = NewEntry.Contributions[Index];
 745       Out.emitBytes(CUInfoSection);
 746       C.Offset = InfoSectionOffset;
 747       InfoSectionOffset += C.Length;
 748     }
 749
 750     if (!CurTUIndexSection.empty()) {
 751       llvm::DWARFSectionKind TUSectionKind;
 752       MCSection *OutSection;
 753       StringRef TypeInputSection;
 754       // Write type units into debug info section for DWARFv5.
 755       if (Version >= 5) {
 756         TUSectionKind = DW_SECT_INFO;
 757         OutSection = InfoSection;
 758         TypeInputSection = DwpSingleInfoSection;
 759       } else {
 760         // Write type units into debug types section for DWARF < 5.
 761         if (CurTypesSection.size() != 1)
 762           return make_error<DWPError>(
 763               "multiple type unit sections in .dwp file");
 764
 765         TUSectionKind = DW_SECT_EXT_TYPES;
 766         OutSection = TypesSection;
 767         TypeInputSection = CurTypesSection.front();
 768       }
 769
 770       DWARFUnitIndex TUIndex(TUSectionKind);
 771       DataExtractor TUIndexData(CurTUIndexSection, Obj.isLittleEndian(), 0);
 772       if (!TUIndex.parse(TUIndexData))
 773         return make_error<DWPError>("failed to parse tu_index");
 774       if (TUIndex.getVersion() != IndexVersion)
 775         return make_error<DWPError>("incompatible tu_index versions, found " +
 776                                     utostr(TUIndex.getVersion()) +
 777                                     " and expecting " + utostr(IndexVersion));
 778
 779       unsigned TypesContributionIndex =
 780           getContributionIndex(TUSectionKind, IndexVersion);
 781       addAllTypesFromDWP(Out, TypeIndexEntries, TUIndex, OutSection,
 782                          TypeInputSection, CurEntry,
 783                          ContributionOffsets[TypesContributionIndex],
 784                          TypesContributionIndex);
 785     }
 786   }
 787
 788   if (Version < 5) {
 789     // Lie about there being no info contributions so the TU index only includes
 790     // the type unit contribution for DWARF < 5. In DWARFv5 the TU index has a
 791     // contribution to the info section, so we do not want to lie about it.
 792     ContributionOffsets[0] = 0;
 793   }
 794   writeIndex(Out, MCOFI.getDwarfTUIndexSection(), ContributionOffsets,
 795              TypeIndexEntries, IndexVersion);
 796
 797   if (Version < 5) {
 798     // Lie about the type contribution for DWARF < 5. In DWARFv5 the type
 799     // section does not exist, so no need to do anything about this.
 800     ContributionOffsets[getContributionIndex(DW_SECT_EXT_TYPES, 2)] = 0;
 801     // Unlie about the info contribution
 802     ContributionOffsets[0] = 1;
 803   }
 804
 805   writeIndex(Out, MCOFI.getDwarfCUIndexSection(), ContributionOffsets,
 806              IndexEntries, IndexVersion);
 807
 808   return Error::success();
 809 }
 810 } // namespace llvm