xref: /freebsd/contrib/llvm-project/llvm/lib/DWP/DWP.cpp (revision 7ef62cebc2f965b0f640263e179276928885e33d) 
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 #include "llvm/Object/ELFObjectFile.h"
20 #include "llvm/Support/MemoryBuffer.h"
21 #include <limits>
22 
23 using namespace llvm;
24 using namespace llvm::object;
25 
26 static mc::RegisterMCTargetOptionsFlags MCTargetOptionsFlags;
27 
28 // Returns the size of debug_str_offsets section headers in bytes.
29 static uint64_t debugStrOffsetsHeaderSize(DataExtractor StrOffsetsData,
30                                           uint16_t DwarfVersion) {
31   if (DwarfVersion <= 4)
32     return 0; // There is no header before dwarf 5.
33   uint64_t Offset = 0;
34   uint64_t Length = StrOffsetsData.getU32(&Offset);
35   if (Length == llvm::dwarf::DW_LENGTH_DWARF64)
36     return 16; // unit length: 12 bytes, version: 2 bytes, padding: 2 bytes.
37   return 8;    // unit length: 4 bytes, version: 2 bytes, padding: 2 bytes.
38 }
39 
40 static uint64_t getCUAbbrev(StringRef Abbrev, uint64_t AbbrCode) {
41   uint64_t Offset = 0;
42   DataExtractor AbbrevData(Abbrev, true, 0);
43   while (AbbrevData.getULEB128(&Offset) != AbbrCode) {
44     // Tag
45     AbbrevData.getULEB128(&Offset);
46     // DW_CHILDREN
47     AbbrevData.getU8(&Offset);
48     // Attributes
49     while (AbbrevData.getULEB128(&Offset) | AbbrevData.getULEB128(&Offset))
50       ;
51   }
52   return Offset;
53 }
54 
55 static Expected<const char *>
56 getIndexedString(dwarf::Form Form, DataExtractor InfoData, uint64_t &InfoOffset,
57                  StringRef StrOffsets, StringRef Str, uint16_t Version) {
58   if (Form == dwarf::DW_FORM_string)
59     return InfoData.getCStr(&InfoOffset);
60   uint64_t StrIndex;
61   switch (Form) {
62   case dwarf::DW_FORM_strx1:
63     StrIndex = InfoData.getU8(&InfoOffset);
64     break;
65   case dwarf::DW_FORM_strx2:
66     StrIndex = InfoData.getU16(&InfoOffset);
67     break;
68   case dwarf::DW_FORM_strx3:
69     StrIndex = InfoData.getU24(&InfoOffset);
70     break;
71   case dwarf::DW_FORM_strx4:
72     StrIndex = InfoData.getU32(&InfoOffset);
73     break;
74   case dwarf::DW_FORM_strx:
75   case dwarf::DW_FORM_GNU_str_index:
76     StrIndex = InfoData.getULEB128(&InfoOffset);
77     break;
78   default:
79     return make_error<DWPError>(
80         "string field must be encoded with one of the following: "
81         "DW_FORM_string, DW_FORM_strx, DW_FORM_strx1, DW_FORM_strx2, "
82         "DW_FORM_strx3, DW_FORM_strx4, or DW_FORM_GNU_str_index.");
83   }
84   DataExtractor StrOffsetsData(StrOffsets, true, 0);
85   uint64_t StrOffsetsOffset = 4 * StrIndex;
86   StrOffsetsOffset += debugStrOffsetsHeaderSize(StrOffsetsData, Version);
87 
88   uint64_t StrOffset = StrOffsetsData.getU32(&StrOffsetsOffset);
89   DataExtractor StrData(Str, true, 0);
90   return StrData.getCStr(&StrOffset);
91 }
92 
93 static Expected<CompileUnitIdentifiers>
94 getCUIdentifiers(InfoSectionUnitHeader &Header, StringRef Abbrev,
95                  StringRef Info, StringRef StrOffsets, StringRef Str) {
96   DataExtractor InfoData(Info, true, 0);
97   uint64_t Offset = Header.HeaderSize;
98   if (Header.Version >= 5 && Header.UnitType != dwarf::DW_UT_split_compile)
99     return make_error<DWPError>(
100         std::string("unit type DW_UT_split_compile type not found in "
101                     "debug_info header. Unexpected unit type 0x" +
102                     utostr(Header.UnitType) + " found"));
103 
104   CompileUnitIdentifiers ID;
105 
106   uint32_t AbbrCode = InfoData.getULEB128(&Offset);
107   DataExtractor AbbrevData(Abbrev, true, 0);
108   uint64_t AbbrevOffset = getCUAbbrev(Abbrev, AbbrCode);
109   auto Tag = static_cast<dwarf::Tag>(AbbrevData.getULEB128(&AbbrevOffset));
110   if (Tag != dwarf::DW_TAG_compile_unit)
111     return make_error<DWPError>("top level DIE is not a compile unit");
112   // DW_CHILDREN
113   AbbrevData.getU8(&AbbrevOffset);
114   uint32_t Name;
115   dwarf::Form Form;
116   while ((Name = AbbrevData.getULEB128(&AbbrevOffset)) |
117              (Form = static_cast<dwarf::Form>(
118                   AbbrevData.getULEB128(&AbbrevOffset))) &&
119          (Name != 0 || Form != 0)) {
120     switch (Name) {
121     case dwarf::DW_AT_name: {
122       Expected<const char *> EName = getIndexedString(
123           Form, InfoData, Offset, StrOffsets, Str, Header.Version);
124       if (!EName)
125         return EName.takeError();
126       ID.Name = *EName;
127       break;
128     }
129     case dwarf::DW_AT_GNU_dwo_name:
130     case dwarf::DW_AT_dwo_name: {
131       Expected<const char *> EName = getIndexedString(
132           Form, InfoData, Offset, StrOffsets, Str, Header.Version);
133       if (!EName)
134         return EName.takeError();
135       ID.DWOName = *EName;
136       break;
137     }
138     case dwarf::DW_AT_GNU_dwo_id:
139       Header.Signature = InfoData.getU64(&Offset);
140       break;
141     default:
142       DWARFFormValue::skipValue(
143           Form, InfoData, &Offset,
144           dwarf::FormParams({Header.Version, Header.AddrSize, Header.Format}));
145     }
146   }
147   if (!Header.Signature)
148     return make_error<DWPError>("compile unit missing dwo_id");
149   ID.Signature = *Header.Signature;
150   return ID;
151 }
152 
153 static bool isSupportedSectionKind(DWARFSectionKind Kind) {
154   return Kind != DW_SECT_EXT_unknown;
155 }
156 
157 namespace llvm {
158 // Convert an internal section identifier into the index to use with
159 // UnitIndexEntry::Contributions.
160 unsigned getContributionIndex(DWARFSectionKind Kind, uint32_t IndexVersion) {
161   assert(serializeSectionKind(Kind, IndexVersion) >= DW_SECT_INFO);
162   return serializeSectionKind(Kind, IndexVersion) - DW_SECT_INFO;
163 }
164 } // namespace llvm
165 
166 // Convert a UnitIndexEntry::Contributions index to the corresponding on-disk
167 // value of the section identifier.
168 static unsigned getOnDiskSectionId(unsigned Index) {
169   return Index + DW_SECT_INFO;
170 }
171 
172 static StringRef getSubsection(StringRef Section,
173                                const DWARFUnitIndex::Entry &Entry,
174                                DWARFSectionKind Kind) {
175   const auto *Off = Entry.getContribution(Kind);
176   if (!Off)
177     return StringRef();
178   return Section.substr(Off->getOffset(), Off->getLength());
179 }
180 
181 static void
182 addAllTypesFromDWP(MCStreamer &Out,
183                    MapVector<uint64_t, UnitIndexEntry> &TypeIndexEntries,
184                    const DWARFUnitIndex &TUIndex, MCSection *OutputTypes,
185                    StringRef Types, const UnitIndexEntry &TUEntry,
186                    uint32_t &TypesOffset, unsigned TypesContributionIndex) {
187   Out.switchSection(OutputTypes);
188   for (const DWARFUnitIndex::Entry &E : TUIndex.getRows()) {
189     auto *I = E.getContributions();
190     if (!I)
191       continue;
192     auto P = TypeIndexEntries.insert(std::make_pair(E.getSignature(), TUEntry));
193     if (!P.second)
194       continue;
195     auto &Entry = P.first->second;
196     // Zero out the debug_info contribution
197     Entry.Contributions[0] = {};
198     for (auto Kind : TUIndex.getColumnKinds()) {
199       if (!isSupportedSectionKind(Kind))
200         continue;
201       auto &C =
202           Entry.Contributions[getContributionIndex(Kind, TUIndex.getVersion())];
203       C.setOffset(C.getOffset() + I->getOffset());
204       C.setLength(I->getLength());
205       ++I;
206     }
207     auto &C = Entry.Contributions[TypesContributionIndex];
208     Out.emitBytes(Types.substr(
209         C.getOffset() -
210             TUEntry.Contributions[TypesContributionIndex].getOffset(),
211         C.getLength()));
212     C.setOffset(TypesOffset);
213     TypesOffset += C.getLength();
214   }
215 }
216 
217 static void addAllTypesFromTypesSection(
218     MCStreamer &Out, MapVector<uint64_t, UnitIndexEntry> &TypeIndexEntries,
219     MCSection *OutputTypes, const std::vector<StringRef> &TypesSections,
220     const UnitIndexEntry &CUEntry, uint32_t &TypesOffset) {
221   for (StringRef Types : TypesSections) {
222     Out.switchSection(OutputTypes);
223     uint64_t Offset = 0;
224     DataExtractor Data(Types, true, 0);
225     while (Data.isValidOffset(Offset)) {
226       UnitIndexEntry Entry = CUEntry;
227       // Zero out the debug_info contribution
228       Entry.Contributions[0] = {};
229       auto &C = Entry.Contributions[getContributionIndex(DW_SECT_EXT_TYPES, 2)];
230       C.setOffset(TypesOffset);
231       auto PrevOffset = Offset;
232       // Length of the unit, including the 4 byte length field.
233       C.setLength(Data.getU32(&Offset) + 4);
234 
235       Data.getU16(&Offset); // Version
236       Data.getU32(&Offset); // Abbrev offset
237       Data.getU8(&Offset);  // Address size
238       auto Signature = Data.getU64(&Offset);
239       Offset = PrevOffset + C.getLength32();
240 
241       auto P = TypeIndexEntries.insert(std::make_pair(Signature, Entry));
242       if (!P.second)
243         continue;
244 
245       Out.emitBytes(Types.substr(PrevOffset, C.getLength32()));
246       TypesOffset += C.getLength32();
247     }
248   }
249 }
250 
251 static std::string buildDWODescription(StringRef Name, StringRef DWPName,
252                                        StringRef DWOName) {
253   std::string Text = "\'";
254   Text += Name;
255   Text += '\'';
256   bool HasDWO = !DWOName.empty();
257   bool HasDWP = !DWPName.empty();
258   if (HasDWO || HasDWP) {
259     Text += " (from ";
260     if (HasDWO) {
261       Text += '\'';
262       Text += DWOName;
263       Text += '\'';
264     }
265     if (HasDWO && HasDWP)
266       Text += " in ";
267     if (!DWPName.empty()) {
268       Text += '\'';
269       Text += DWPName;
270       Text += '\'';
271     }
272     Text += ")";
273   }
274   return Text;
275 }
276 
277 static Error createError(StringRef Name, Error E) {
278   return make_error<DWPError>(
279       ("failure while decompressing compressed section: '" + Name + "', " +
280        llvm::toString(std::move(E)))
281           .str());
282 }
283 
284 static Error
285 handleCompressedSection(std::deque<SmallString<32>> &UncompressedSections,
286                         SectionRef Sec, StringRef Name, StringRef &Contents) {
287   auto *Obj = dyn_cast<ELFObjectFileBase>(Sec.getObject());
288   if (!Obj ||
289       !(static_cast<ELFSectionRef>(Sec).getFlags() & ELF::SHF_COMPRESSED))
290     return Error::success();
291   bool IsLE = isa<object::ELF32LEObjectFile>(Obj) ||
292               isa<object::ELF64LEObjectFile>(Obj);
293   bool Is64 = isa<object::ELF64LEObjectFile>(Obj) ||
294               isa<object::ELF64BEObjectFile>(Obj);
295   Expected<Decompressor> Dec = Decompressor::create(Name, Contents, IsLE, Is64);
296   if (!Dec)
297     return createError(Name, Dec.takeError());
298 
299   UncompressedSections.emplace_back();
300   if (Error E = Dec->resizeAndDecompress(UncompressedSections.back()))
301     return createError(Name, std::move(E));
302 
303   Contents = UncompressedSections.back();
304   return Error::success();
305 }
306 
307 namespace llvm {
308 // Parse and return the header of an info section compile/type unit.
309 Expected<InfoSectionUnitHeader> parseInfoSectionUnitHeader(StringRef Info) {
310   InfoSectionUnitHeader Header;
311   Error Err = Error::success();
312   uint64_t Offset = 0;
313   DWARFDataExtractor InfoData(Info, true, 0);
314   std::tie(Header.Length, Header.Format) =
315       InfoData.getInitialLength(&Offset, &Err);
316   if (Err)
317     return make_error<DWPError>("cannot parse compile unit length: " +
318                                 llvm::toString(std::move(Err)));
319 
320   if (!InfoData.isValidOffset(Offset + (Header.Length - 1))) {
321     return make_error<DWPError>(
322         "compile unit exceeds .debug_info section range: " +
323         utostr(Offset + Header.Length) + " >= " + utostr(InfoData.size()));
324   }
325 
326   Header.Version = InfoData.getU16(&Offset, &Err);
327   if (Err)
328     return make_error<DWPError>("cannot parse compile unit version: " +
329                                 llvm::toString(std::move(Err)));
330 
331   uint64_t MinHeaderLength;
332   if (Header.Version >= 5) {
333     // Size: Version (2), UnitType (1), AddrSize (1), DebugAbbrevOffset (4),
334     // Signature (8)
335     MinHeaderLength = 16;
336   } else {
337     // Size: Version (2), DebugAbbrevOffset (4), AddrSize (1)
338     MinHeaderLength = 7;
339   }
340   if (Header.Length < MinHeaderLength) {
341     return make_error<DWPError>("unit length is too small: expected at least " +
342                                 utostr(MinHeaderLength) + " got " +
343                                 utostr(Header.Length) + ".");
344   }
345   if (Header.Version >= 5) {
346     Header.UnitType = InfoData.getU8(&Offset);
347     Header.AddrSize = InfoData.getU8(&Offset);
348     Header.DebugAbbrevOffset = InfoData.getU32(&Offset);
349     Header.Signature = InfoData.getU64(&Offset);
350     if (Header.UnitType == dwarf::DW_UT_split_type) {
351       // Type offset.
352       MinHeaderLength += 4;
353       if (Header.Length < MinHeaderLength)
354         return make_error<DWPError>("type unit is missing type offset");
355       InfoData.getU32(&Offset);
356     }
357   } else {
358     // Note that, address_size and debug_abbrev_offset fields have switched
359     // places between dwarf version 4 and 5.
360     Header.DebugAbbrevOffset = InfoData.getU32(&Offset);
361     Header.AddrSize = InfoData.getU8(&Offset);
362   }
363 
364   Header.HeaderSize = Offset;
365   return Header;
366 }
367 
368 void writeStringsAndOffsets(MCStreamer &Out, DWPStringPool &Strings,
369                             MCSection *StrOffsetSection,
370                             StringRef CurStrSection,
371                             StringRef CurStrOffsetSection, uint16_t Version) {
372   // Could possibly produce an error or warning if one of these was non-null but
373   // the other was null.
374   if (CurStrSection.empty() || CurStrOffsetSection.empty())
375     return;
376 
377   DenseMap<uint64_t, uint32_t> OffsetRemapping;
378 
379   DataExtractor Data(CurStrSection, true, 0);
380   uint64_t LocalOffset = 0;
381   uint64_t PrevOffset = 0;
382   while (const char *S = Data.getCStr(&LocalOffset)) {
383     OffsetRemapping[PrevOffset] =
384         Strings.getOffset(S, LocalOffset - PrevOffset);
385     PrevOffset = LocalOffset;
386   }
387 
388   Data = DataExtractor(CurStrOffsetSection, true, 0);
389 
390   Out.switchSection(StrOffsetSection);
391 
392   uint64_t HeaderSize = debugStrOffsetsHeaderSize(Data, Version);
393   uint64_t Offset = 0;
394   uint64_t Size = CurStrOffsetSection.size();
395   // FIXME: This can be caused by bad input and should be handled as such.
396   assert(HeaderSize <= Size && "StrOffsetSection size is less than its header");
397   // Copy the header to the output.
398   Out.emitBytes(Data.getBytes(&Offset, HeaderSize));
399   while (Offset < Size) {
400     auto OldOffset = Data.getU32(&Offset);
401     auto NewOffset = OffsetRemapping[OldOffset];
402     Out.emitIntValue(NewOffset, 4);
403   }
404 }
405 
406 enum AccessField { Offset, Length };
407 void writeIndexTable(MCStreamer &Out, ArrayRef<unsigned> ContributionOffsets,
408                      const MapVector<uint64_t, UnitIndexEntry> &IndexEntries,
409                      const AccessField &Field) {
410   for (const auto &E : IndexEntries)
411     for (size_t I = 0; I != std::size(E.second.Contributions); ++I)
412       if (ContributionOffsets[I])
413         Out.emitIntValue((Field == AccessField::Offset
414                               ? E.second.Contributions[I].getOffset32()
415                               : E.second.Contributions[I].getLength32()),
416                          4);
417 }
418 
419 void writeIndex(MCStreamer &Out, MCSection *Section,
420                 ArrayRef<unsigned> ContributionOffsets,
421                 const MapVector<uint64_t, UnitIndexEntry> &IndexEntries,
422                 uint32_t IndexVersion) {
423   if (IndexEntries.empty())
424     return;
425 
426   unsigned Columns = 0;
427   for (auto &C : ContributionOffsets)
428     if (C)
429       ++Columns;
430 
431   std::vector<unsigned> Buckets(NextPowerOf2(3 * IndexEntries.size() / 2));
432   uint64_t Mask = Buckets.size() - 1;
433   size_t I = 0;
434   for (const auto &P : IndexEntries) {
435     auto S = P.first;
436     auto H = S & Mask;
437     auto HP = ((S >> 32) & Mask) | 1;
438     while (Buckets[H]) {
439       assert(S != IndexEntries.begin()[Buckets[H] - 1].first &&
440              "Duplicate unit");
441       H = (H + HP) & Mask;
442     }
443     Buckets[H] = I + 1;
444     ++I;
445   }
446 
447   Out.switchSection(Section);
448   Out.emitIntValue(IndexVersion, 4);        // Version
449   Out.emitIntValue(Columns, 4);             // Columns
450   Out.emitIntValue(IndexEntries.size(), 4); // Num Units
451   Out.emitIntValue(Buckets.size(), 4);      // Num Buckets
452 
453   // Write the signatures.
454   for (const auto &I : Buckets)
455     Out.emitIntValue(I ? IndexEntries.begin()[I - 1].first : 0, 8);
456 
457   // Write the indexes.
458   for (const auto &I : Buckets)
459     Out.emitIntValue(I, 4);
460 
461   // Write the column headers (which sections will appear in the table)
462   for (size_t I = 0; I != ContributionOffsets.size(); ++I)
463     if (ContributionOffsets[I])
464       Out.emitIntValue(getOnDiskSectionId(I), 4);
465 
466   // Write the offsets.
467   writeIndexTable(Out, ContributionOffsets, IndexEntries, AccessField::Offset);
468 
469   // Write the lengths.
470   writeIndexTable(Out, ContributionOffsets, IndexEntries, AccessField::Length);
471 }
472 
473 Error buildDuplicateError(const std::pair<uint64_t, UnitIndexEntry> &PrevE,
474                           const CompileUnitIdentifiers &ID, StringRef DWPName) {
475   return make_error<DWPError>(
476       std::string("duplicate DWO ID (") + utohexstr(PrevE.first) + ") in " +
477       buildDWODescription(PrevE.second.Name, PrevE.second.DWPName,
478                           PrevE.second.DWOName) +
479       " and " + buildDWODescription(ID.Name, DWPName, ID.DWOName));
480 }
481 
482 Error handleSection(
483     const StringMap<std::pair<MCSection *, DWARFSectionKind>> &KnownSections,
484     const MCSection *StrSection, const MCSection *StrOffsetSection,
485     const MCSection *TypesSection, const MCSection *CUIndexSection,
486     const MCSection *TUIndexSection, const MCSection *InfoSection,
487     const SectionRef &Section, MCStreamer &Out,
488     std::deque<SmallString<32>> &UncompressedSections,
489     uint32_t (&ContributionOffsets)[8], UnitIndexEntry &CurEntry,
490     StringRef &CurStrSection, StringRef &CurStrOffsetSection,
491     std::vector<StringRef> &CurTypesSection,
492     std::vector<StringRef> &CurInfoSection, StringRef &AbbrevSection,
493     StringRef &CurCUIndexSection, StringRef &CurTUIndexSection,
494     std::vector<std::pair<DWARFSectionKind, uint32_t>> &SectionLength) {
495   if (Section.isBSS())
496     return Error::success();
497 
498   if (Section.isVirtual())
499     return Error::success();
500 
501   Expected<StringRef> NameOrErr = Section.getName();
502   if (!NameOrErr)
503     return NameOrErr.takeError();
504   StringRef Name = *NameOrErr;
505 
506   Expected<StringRef> ContentsOrErr = Section.getContents();
507   if (!ContentsOrErr)
508     return ContentsOrErr.takeError();
509   StringRef Contents = *ContentsOrErr;
510 
511   if (auto Err = handleCompressedSection(UncompressedSections, Section, Name,
512                                          Contents))
513     return Err;
514 
515   Name = Name.substr(Name.find_first_not_of("._"));
516 
517   auto SectionPair = KnownSections.find(Name);
518   if (SectionPair == KnownSections.end())
519     return Error::success();
520 
521   if (DWARFSectionKind Kind = SectionPair->second.second) {
522     if (Kind != DW_SECT_EXT_TYPES && Kind != DW_SECT_INFO) {
523       SectionLength.push_back(std::make_pair(Kind, Contents.size()));
524     }
525 
526     if (Kind == DW_SECT_ABBREV) {
527       AbbrevSection = Contents;
528     }
529   }
530 
531   MCSection *OutSection = SectionPair->second.first;
532   if (OutSection == StrOffsetSection)
533     CurStrOffsetSection = Contents;
534   else if (OutSection == StrSection)
535     CurStrSection = Contents;
536   else if (OutSection == TypesSection)
537     CurTypesSection.push_back(Contents);
538   else if (OutSection == CUIndexSection)
539     CurCUIndexSection = Contents;
540   else if (OutSection == TUIndexSection)
541     CurTUIndexSection = Contents;
542   else if (OutSection == InfoSection)
543     CurInfoSection.push_back(Contents);
544   else {
545     Out.switchSection(OutSection);
546     Out.emitBytes(Contents);
547   }
548   return Error::success();
549 }
550 
551 Error write(MCStreamer &Out, ArrayRef<std::string> Inputs) {
552   const auto &MCOFI = *Out.getContext().getObjectFileInfo();
553   MCSection *const StrSection = MCOFI.getDwarfStrDWOSection();
554   MCSection *const StrOffsetSection = MCOFI.getDwarfStrOffDWOSection();
555   MCSection *const TypesSection = MCOFI.getDwarfTypesDWOSection();
556   MCSection *const CUIndexSection = MCOFI.getDwarfCUIndexSection();
557   MCSection *const TUIndexSection = MCOFI.getDwarfTUIndexSection();
558   MCSection *const InfoSection = MCOFI.getDwarfInfoDWOSection();
559   const StringMap<std::pair<MCSection *, DWARFSectionKind>> KnownSections = {
560       {"debug_info.dwo", {InfoSection, DW_SECT_INFO}},
561       {"debug_types.dwo", {MCOFI.getDwarfTypesDWOSection(), DW_SECT_EXT_TYPES}},
562       {"debug_str_offsets.dwo", {StrOffsetSection, DW_SECT_STR_OFFSETS}},
563       {"debug_str.dwo", {StrSection, static_cast<DWARFSectionKind>(0)}},
564       {"debug_loc.dwo", {MCOFI.getDwarfLocDWOSection(), DW_SECT_EXT_LOC}},
565       {"debug_line.dwo", {MCOFI.getDwarfLineDWOSection(), DW_SECT_LINE}},
566       {"debug_macro.dwo", {MCOFI.getDwarfMacroDWOSection(), DW_SECT_MACRO}},
567       {"debug_abbrev.dwo", {MCOFI.getDwarfAbbrevDWOSection(), DW_SECT_ABBREV}},
568       {"debug_loclists.dwo",
569        {MCOFI.getDwarfLoclistsDWOSection(), DW_SECT_LOCLISTS}},
570       {"debug_rnglists.dwo",
571        {MCOFI.getDwarfRnglistsDWOSection(), DW_SECT_RNGLISTS}},
572       {"debug_cu_index", {CUIndexSection, static_cast<DWARFSectionKind>(0)}},
573       {"debug_tu_index", {TUIndexSection, static_cast<DWARFSectionKind>(0)}}};
574 
575   MapVector<uint64_t, UnitIndexEntry> IndexEntries;
576   MapVector<uint64_t, UnitIndexEntry> TypeIndexEntries;
577 
578   uint32_t ContributionOffsets[8] = {};
579   uint16_t Version = 0;
580   uint32_t IndexVersion = 0;
581 
582   DWPStringPool Strings(Out, StrSection);
583 
584   SmallVector<OwningBinary<object::ObjectFile>, 128> Objects;
585   Objects.reserve(Inputs.size());
586 
587   std::deque<SmallString<32>> UncompressedSections;
588 
589   for (const auto &Input : Inputs) {
590     auto ErrOrObj = object::ObjectFile::createObjectFile(Input);
591     if (!ErrOrObj) {
592       return handleErrors(ErrOrObj.takeError(),
593                           [&](std::unique_ptr<ECError> EC) -> Error {
594                             return createFileError(Input, Error(std::move(EC)));
595                           });
596     }
597 
598     auto &Obj = *ErrOrObj->getBinary();
599     Objects.push_back(std::move(*ErrOrObj));
600 
601     UnitIndexEntry CurEntry = {};
602 
603     StringRef CurStrSection;
604     StringRef CurStrOffsetSection;
605     std::vector<StringRef> CurTypesSection;
606     std::vector<StringRef> CurInfoSection;
607     StringRef AbbrevSection;
608     StringRef CurCUIndexSection;
609     StringRef CurTUIndexSection;
610 
611     // This maps each section contained in this file to its length.
612     // This information is later on used to calculate the contributions,
613     // i.e. offset and length, of each compile/type unit to a section.
614     std::vector<std::pair<DWARFSectionKind, uint32_t>> SectionLength;
615 
616     for (const auto &Section : Obj.sections())
617       if (auto Err = handleSection(
618               KnownSections, StrSection, StrOffsetSection, TypesSection,
619               CUIndexSection, TUIndexSection, InfoSection, Section, Out,
620               UncompressedSections, ContributionOffsets, CurEntry,
621               CurStrSection, CurStrOffsetSection, CurTypesSection,
622               CurInfoSection, AbbrevSection, CurCUIndexSection,
623               CurTUIndexSection, SectionLength))
624         return Err;
625 
626     if (CurInfoSection.empty())
627       continue;
628 
629     Expected<InfoSectionUnitHeader> HeaderOrErr =
630         parseInfoSectionUnitHeader(CurInfoSection.front());
631     if (!HeaderOrErr)
632       return HeaderOrErr.takeError();
633     InfoSectionUnitHeader &Header = *HeaderOrErr;
634 
635     if (Version == 0) {
636       Version = Header.Version;
637       IndexVersion = Version < 5 ? 2 : 5;
638     } else if (Version != Header.Version) {
639       return make_error<DWPError>("incompatible DWARF compile unit versions.");
640     }
641 
642     writeStringsAndOffsets(Out, Strings, StrOffsetSection, CurStrSection,
643                            CurStrOffsetSection, Header.Version);
644 
645     for (auto Pair : SectionLength) {
646       auto Index = getContributionIndex(Pair.first, IndexVersion);
647       CurEntry.Contributions[Index].setOffset(ContributionOffsets[Index]);
648       CurEntry.Contributions[Index].setLength(Pair.second);
649       ContributionOffsets[Index] += CurEntry.Contributions[Index].getLength32();
650     }
651 
652     uint32_t &InfoSectionOffset =
653         ContributionOffsets[getContributionIndex(DW_SECT_INFO, IndexVersion)];
654     if (CurCUIndexSection.empty()) {
655       bool FoundCUUnit = false;
656       Out.switchSection(InfoSection);
657       for (StringRef Info : CurInfoSection) {
658         uint64_t UnitOffset = 0;
659         while (Info.size() > UnitOffset) {
660           Expected<InfoSectionUnitHeader> HeaderOrError =
661               parseInfoSectionUnitHeader(Info.substr(UnitOffset, Info.size()));
662           if (!HeaderOrError)
663             return HeaderOrError.takeError();
664           InfoSectionUnitHeader &Header = *HeaderOrError;
665 
666           UnitIndexEntry Entry = CurEntry;
667           auto &C = Entry.Contributions[getContributionIndex(DW_SECT_INFO,
668                                                              IndexVersion)];
669           C.setOffset(InfoSectionOffset);
670           C.setLength(Header.Length + 4);
671 
672           if (std::numeric_limits<uint32_t>::max() - InfoSectionOffset <
673               C.getLength32())
674             return make_error<DWPError>(
675                 "debug information section offset is greater than 4GB");
676 
677           UnitOffset += C.getLength32();
678           if (Header.Version < 5 ||
679               Header.UnitType == dwarf::DW_UT_split_compile) {
680             Expected<CompileUnitIdentifiers> EID = getCUIdentifiers(
681                 Header, AbbrevSection,
682                 Info.substr(UnitOffset - C.getLength32(), C.getLength32()),
683                 CurStrOffsetSection, CurStrSection);
684 
685             if (!EID)
686               return createFileError(Input, EID.takeError());
687             const auto &ID = *EID;
688             auto P = IndexEntries.insert(std::make_pair(ID.Signature, Entry));
689             if (!P.second)
690               return buildDuplicateError(*P.first, ID, "");
691             P.first->second.Name = ID.Name;
692             P.first->second.DWOName = ID.DWOName;
693 
694             FoundCUUnit = true;
695           } else if (Header.UnitType == dwarf::DW_UT_split_type) {
696             auto P = TypeIndexEntries.insert(
697                 std::make_pair(*Header.Signature, Entry));
698             if (!P.second)
699               continue;
700           }
701           Out.emitBytes(
702               Info.substr(UnitOffset - C.getLength32(), C.getLength32()));
703           InfoSectionOffset += C.getLength32();
704         }
705       }
706 
707       if (!FoundCUUnit)
708         return make_error<DWPError>("no compile unit found in file: " + Input);
709 
710       if (IndexVersion == 2) {
711         // Add types from the .debug_types section from DWARF < 5.
712         addAllTypesFromTypesSection(
713             Out, TypeIndexEntries, TypesSection, CurTypesSection, CurEntry,
714             ContributionOffsets[getContributionIndex(DW_SECT_EXT_TYPES, 2)]);
715       }
716       continue;
717     }
718 
719     if (CurInfoSection.size() != 1)
720       return make_error<DWPError>("expected exactly one occurrence of a debug "
721                                   "info section in a .dwp file");
722     StringRef DwpSingleInfoSection = CurInfoSection.front();
723 
724     DWARFUnitIndex CUIndex(DW_SECT_INFO);
725     DataExtractor CUIndexData(CurCUIndexSection, Obj.isLittleEndian(), 0);
726     if (!CUIndex.parse(CUIndexData))
727       return make_error<DWPError>("failed to parse cu_index");
728     if (CUIndex.getVersion() != IndexVersion)
729       return make_error<DWPError>("incompatible cu_index versions, found " +
730                                   utostr(CUIndex.getVersion()) +
731                                   " and expecting " + utostr(IndexVersion));
732 
733     Out.switchSection(InfoSection);
734     for (const DWARFUnitIndex::Entry &E : CUIndex.getRows()) {
735       auto *I = E.getContributions();
736       if (!I)
737         continue;
738       auto P = IndexEntries.insert(std::make_pair(E.getSignature(), CurEntry));
739       StringRef CUInfoSection =
740           getSubsection(DwpSingleInfoSection, E, DW_SECT_INFO);
741       Expected<InfoSectionUnitHeader> HeaderOrError =
742           parseInfoSectionUnitHeader(CUInfoSection);
743       if (!HeaderOrError)
744         return HeaderOrError.takeError();
745       InfoSectionUnitHeader &Header = *HeaderOrError;
746 
747       Expected<CompileUnitIdentifiers> EID = getCUIdentifiers(
748           Header, getSubsection(AbbrevSection, E, DW_SECT_ABBREV),
749           CUInfoSection,
750           getSubsection(CurStrOffsetSection, E, DW_SECT_STR_OFFSETS),
751           CurStrSection);
752       if (!EID)
753         return createFileError(Input, EID.takeError());
754       const auto &ID = *EID;
755       if (!P.second)
756         return buildDuplicateError(*P.first, ID, Input);
757       auto &NewEntry = P.first->second;
758       NewEntry.Name = ID.Name;
759       NewEntry.DWOName = ID.DWOName;
760       NewEntry.DWPName = Input;
761       for (auto Kind : CUIndex.getColumnKinds()) {
762         if (!isSupportedSectionKind(Kind))
763           continue;
764         auto &C =
765             NewEntry.Contributions[getContributionIndex(Kind, IndexVersion)];
766         C.setOffset(C.getOffset() + I->getOffset());
767         C.setLength(I->getLength());
768         ++I;
769       }
770       unsigned Index = getContributionIndex(DW_SECT_INFO, IndexVersion);
771       auto &C = NewEntry.Contributions[Index];
772       Out.emitBytes(CUInfoSection);
773       C.setOffset(InfoSectionOffset);
774       InfoSectionOffset += C.getLength32();
775     }
776 
777     if (!CurTUIndexSection.empty()) {
778       llvm::DWARFSectionKind TUSectionKind;
779       MCSection *OutSection;
780       StringRef TypeInputSection;
781       // Write type units into debug info section for DWARFv5.
782       if (Version >= 5) {
783         TUSectionKind = DW_SECT_INFO;
784         OutSection = InfoSection;
785         TypeInputSection = DwpSingleInfoSection;
786       } else {
787         // Write type units into debug types section for DWARF < 5.
788         if (CurTypesSection.size() != 1)
789           return make_error<DWPError>(
790               "multiple type unit sections in .dwp file");
791 
792         TUSectionKind = DW_SECT_EXT_TYPES;
793         OutSection = TypesSection;
794         TypeInputSection = CurTypesSection.front();
795       }
796 
797       DWARFUnitIndex TUIndex(TUSectionKind);
798       DataExtractor TUIndexData(CurTUIndexSection, Obj.isLittleEndian(), 0);
799       if (!TUIndex.parse(TUIndexData))
800         return make_error<DWPError>("failed to parse tu_index");
801       if (TUIndex.getVersion() != IndexVersion)
802         return make_error<DWPError>("incompatible tu_index versions, found " +
803                                     utostr(TUIndex.getVersion()) +
804                                     " and expecting " + utostr(IndexVersion));
805 
806       unsigned TypesContributionIndex =
807           getContributionIndex(TUSectionKind, IndexVersion);
808       addAllTypesFromDWP(Out, TypeIndexEntries, TUIndex, OutSection,
809                          TypeInputSection, CurEntry,
810                          ContributionOffsets[TypesContributionIndex],
811                          TypesContributionIndex);
812     }
813   }
814 
815   if (Version < 5) {
816     // Lie about there being no info contributions so the TU index only includes
817     // the type unit contribution for DWARF < 5. In DWARFv5 the TU index has a
818     // contribution to the info section, so we do not want to lie about it.
819     ContributionOffsets[0] = 0;
820   }
821   writeIndex(Out, MCOFI.getDwarfTUIndexSection(), ContributionOffsets,
822              TypeIndexEntries, IndexVersion);
823 
824   if (Version < 5) {
825     // Lie about the type contribution for DWARF < 5. In DWARFv5 the type
826     // section does not exist, so no need to do anything about this.
827     ContributionOffsets[getContributionIndex(DW_SECT_EXT_TYPES, 2)] = 0;
828     // Unlie about the info contribution
829     ContributionOffsets[0] = 1;
830   }
831 
832   writeIndex(Out, MCOFI.getDwarfCUIndexSection(), ContributionOffsets,
833              IndexEntries, IndexVersion);
834 
835   return Error::success();
836 }
837 } // namespace llvm
838