xref: /freebsd/contrib/llvm-project/llvm/tools/llvm-dwp/llvm-dwp.cpp (revision 19261079b74319502c6ffa1249920079f0f69a72) 
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 "DWPError.h"
14 #include "DWPStringPool.h"
15 #include "llvm/ADT/MapVector.h"
16 #include "llvm/ADT/Optional.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
19 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
20 #include "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
21 #include "llvm/MC/MCAsmBackend.h"
22 #include "llvm/MC/MCAsmInfo.h"
23 #include "llvm/MC/MCCodeEmitter.h"
24 #include "llvm/MC/MCContext.h"
25 #include "llvm/MC/MCInstrInfo.h"
26 #include "llvm/MC/MCObjectFileInfo.h"
27 #include "llvm/MC/MCObjectWriter.h"
28 #include "llvm/MC/MCRegisterInfo.h"
29 #include "llvm/MC/MCStreamer.h"
30 #include "llvm/MC/MCTargetOptionsCommandFlags.h"
31 #include "llvm/Object/Decompressor.h"
32 #include "llvm/Object/ObjectFile.h"
33 #include "llvm/Support/CommandLine.h"
34 #include "llvm/Support/DataExtractor.h"
35 #include "llvm/Support/Error.h"
36 #include "llvm/Support/FileSystem.h"
37 #include "llvm/Support/InitLLVM.h"
38 #include "llvm/Support/MathExtras.h"
39 #include "llvm/Support/MemoryBuffer.h"
40 #include "llvm/Support/Path.h"
41 #include "llvm/Support/TargetRegistry.h"
42 #include "llvm/Support/TargetSelect.h"
43 #include "llvm/Support/ToolOutputFile.h"
44 #include "llvm/Support/WithColor.h"
45 #include "llvm/Support/raw_ostream.h"
46 
47 using namespace llvm;
48 using namespace llvm::object;
49 
50 static mc::RegisterMCTargetOptionsFlags MCTargetOptionsFlags;
51 
52 cl::OptionCategory DwpCategory("Specific Options");
53 static cl::list<std::string> InputFiles(cl::Positional, cl::ZeroOrMore,
54                                         cl::desc("<input files>"),
55                                         cl::cat(DwpCategory));
56 
57 static cl::list<std::string> ExecFilenames(
58     "e", cl::ZeroOrMore,
59     cl::desc("Specify the executable/library files to get the list of *.dwo from"),
60     cl::value_desc("filename"), cl::cat(DwpCategory));
61 
62 static cl::opt<std::string> OutputFilename(cl::Required, "o",
63                                            cl::desc("Specify the output file."),
64                                            cl::value_desc("filename"),
65                                            cl::cat(DwpCategory));
66 
67 static void writeStringsAndOffsets(MCStreamer &Out, DWPStringPool &Strings,
68                                    MCSection *StrOffsetSection,
69                                    StringRef CurStrSection,
70                                    StringRef CurStrOffsetSection) {
71   // Could possibly produce an error or warning if one of these was non-null but
72   // the other was null.
73   if (CurStrSection.empty() || CurStrOffsetSection.empty())
74     return;
75 
76   DenseMap<uint64_t, uint32_t> OffsetRemapping;
77 
78   DataExtractor Data(CurStrSection, true, 0);
79   uint64_t LocalOffset = 0;
80   uint64_t PrevOffset = 0;
81   while (const char *s = Data.getCStr(&LocalOffset)) {
82     OffsetRemapping[PrevOffset] =
83         Strings.getOffset(s, LocalOffset - PrevOffset);
84     PrevOffset = LocalOffset;
85   }
86 
87   Data = DataExtractor(CurStrOffsetSection, true, 0);
88 
89   Out.SwitchSection(StrOffsetSection);
90 
91   uint64_t Offset = 0;
92   uint64_t Size = CurStrOffsetSection.size();
93   while (Offset < Size) {
94     auto OldOffset = Data.getU32(&Offset);
95     auto NewOffset = OffsetRemapping[OldOffset];
96     Out.emitIntValue(NewOffset, 4);
97   }
98 }
99 
100 static uint64_t getCUAbbrev(StringRef Abbrev, uint64_t AbbrCode) {
101   uint64_t CurCode;
102   uint64_t Offset = 0;
103   DataExtractor AbbrevData(Abbrev, true, 0);
104   while ((CurCode = AbbrevData.getULEB128(&Offset)) != AbbrCode) {
105     // Tag
106     AbbrevData.getULEB128(&Offset);
107     // DW_CHILDREN
108     AbbrevData.getU8(&Offset);
109     // Attributes
110     while (AbbrevData.getULEB128(&Offset) | AbbrevData.getULEB128(&Offset))
111       ;
112   }
113   return Offset;
114 }
115 
116 struct CompileUnitIdentifiers {
117   uint64_t Signature = 0;
118   const char *Name = "";
119   const char *DWOName = "";
120 };
121 
122 static Expected<const char *>
123 getIndexedString(dwarf::Form Form, DataExtractor InfoData,
124                  uint64_t &InfoOffset, StringRef StrOffsets, StringRef Str) {
125   if (Form == dwarf::DW_FORM_string)
126     return InfoData.getCStr(&InfoOffset);
127   if (Form != dwarf::DW_FORM_GNU_str_index)
128     return make_error<DWPError>(
129         "string field encoded without DW_FORM_string or DW_FORM_GNU_str_index");
130   auto StrIndex = InfoData.getULEB128(&InfoOffset);
131   DataExtractor StrOffsetsData(StrOffsets, true, 0);
132   uint64_t StrOffsetsOffset = 4 * StrIndex;
133   uint64_t StrOffset = StrOffsetsData.getU32(&StrOffsetsOffset);
134   DataExtractor StrData(Str, true, 0);
135   return StrData.getCStr(&StrOffset);
136 }
137 
138 static Expected<CompileUnitIdentifiers> getCUIdentifiers(StringRef Abbrev,
139                                                          StringRef Info,
140                                                          StringRef StrOffsets,
141                                                          StringRef Str) {
142   uint64_t Offset = 0;
143   DataExtractor InfoData(Info, true, 0);
144   dwarf::DwarfFormat Format = dwarf::DwarfFormat::DWARF32;
145   uint64_t Length = InfoData.getU32(&Offset);
146   CompileUnitIdentifiers ID;
147   Optional<uint64_t> Signature = None;
148   // If the length is 0xffffffff, then this indictes that this is a DWARF 64
149   // stream and the length is actually encoded into a 64 bit value that follows.
150   if (Length == 0xffffffffU) {
151     Format = dwarf::DwarfFormat::DWARF64;
152     Length = InfoData.getU64(&Offset);
153   }
154   uint16_t Version = InfoData.getU16(&Offset);
155   if (Version >= 5) {
156     auto UnitType = InfoData.getU8(&Offset);
157     if (UnitType != dwarf::DW_UT_split_compile)
158       return make_error<DWPError>(
159           std::string("unit type DW_UT_split_compile type not found in "
160                       "debug_info header. Unexpected unit type 0x" +
161                       utostr(UnitType) + " found"));
162   }
163   InfoData.getU32(&Offset); // Abbrev offset (should be zero)
164   uint8_t AddrSize = InfoData.getU8(&Offset);
165   if (Version >= 5)
166     Signature = InfoData.getU64(&Offset);
167   uint32_t AbbrCode = InfoData.getULEB128(&Offset);
168 
169   DataExtractor AbbrevData(Abbrev, true, 0);
170   uint64_t AbbrevOffset = getCUAbbrev(Abbrev, AbbrCode);
171   auto Tag = static_cast<dwarf::Tag>(AbbrevData.getULEB128(&AbbrevOffset));
172   if (Tag != dwarf::DW_TAG_compile_unit)
173     return make_error<DWPError>("top level DIE is not a compile unit");
174   // DW_CHILDREN
175   AbbrevData.getU8(&AbbrevOffset);
176   uint32_t Name;
177   dwarf::Form Form;
178   while ((Name = AbbrevData.getULEB128(&AbbrevOffset)) |
179          (Form = static_cast<dwarf::Form>(AbbrevData.getULEB128(&AbbrevOffset))) &&
180          (Name != 0 || Form != 0)) {
181     switch (Name) {
182     case dwarf::DW_AT_name: {
183       Expected<const char *> EName =
184           getIndexedString(Form, InfoData, Offset, StrOffsets, Str);
185       if (!EName)
186         return EName.takeError();
187       ID.Name = *EName;
188       break;
189     }
190     case dwarf::DW_AT_GNU_dwo_name:
191     case dwarf::DW_AT_dwo_name: {
192       Expected<const char *> EName =
193           getIndexedString(Form, InfoData, Offset, StrOffsets, Str);
194       if (!EName)
195         return EName.takeError();
196       ID.DWOName = *EName;
197       break;
198     }
199     case dwarf::DW_AT_GNU_dwo_id:
200       Signature = InfoData.getU64(&Offset);
201       break;
202     default:
203       DWARFFormValue::skipValue(Form, InfoData, &Offset,
204                                 dwarf::FormParams({Version, AddrSize, Format}));
205     }
206   }
207   if (!Signature)
208     return make_error<DWPError>("compile unit missing dwo_id");
209   ID.Signature = *Signature;
210   return ID;
211 }
212 
213 struct UnitIndexEntry {
214   DWARFUnitIndex::Entry::SectionContribution Contributions[8];
215   std::string Name;
216   std::string DWOName;
217   StringRef DWPName;
218 };
219 
220 static bool isSupportedSectionKind(DWARFSectionKind Kind) {
221   return Kind != DW_SECT_EXT_unknown;
222 }
223 
224 // Convert an internal section identifier into the index to use with
225 // UnitIndexEntry::Contributions.
226 static unsigned getContributionIndex(DWARFSectionKind Kind) {
227   // Assuming the pre-standard DWP format.
228   assert(serializeSectionKind(Kind, 2) >= DW_SECT_INFO);
229   return serializeSectionKind(Kind, 2) - DW_SECT_INFO;
230 }
231 
232 // Convert a UnitIndexEntry::Contributions index to the corresponding on-disk
233 // value of the section identifier.
234 static unsigned getOnDiskSectionId(unsigned Index) {
235   return Index + DW_SECT_INFO;
236 }
237 
238 static StringRef getSubsection(StringRef Section,
239                                const DWARFUnitIndex::Entry &Entry,
240                                DWARFSectionKind Kind) {
241   const auto *Off = Entry.getContribution(Kind);
242   if (!Off)
243     return StringRef();
244   return Section.substr(Off->Offset, Off->Length);
245 }
246 
247 static void addAllTypesFromDWP(
248     MCStreamer &Out, MapVector<uint64_t, UnitIndexEntry> &TypeIndexEntries,
249     const DWARFUnitIndex &TUIndex, MCSection *OutputTypes, StringRef Types,
250     const UnitIndexEntry &TUEntry, uint32_t &TypesOffset) {
251   Out.SwitchSection(OutputTypes);
252   for (const DWARFUnitIndex::Entry &E : TUIndex.getRows()) {
253     auto *I = E.getContributions();
254     if (!I)
255       continue;
256     auto P = TypeIndexEntries.insert(std::make_pair(E.getSignature(), TUEntry));
257     if (!P.second)
258       continue;
259     auto &Entry = P.first->second;
260     // Zero out the debug_info contribution
261     Entry.Contributions[0] = {};
262     for (auto Kind : TUIndex.getColumnKinds()) {
263       if (!isSupportedSectionKind(Kind))
264         continue;
265       auto &C = Entry.Contributions[getContributionIndex(Kind)];
266       C.Offset += I->Offset;
267       C.Length = I->Length;
268       ++I;
269     }
270     unsigned TypesIndex = getContributionIndex(DW_SECT_EXT_TYPES);
271     auto &C = Entry.Contributions[TypesIndex];
272     Out.emitBytes(Types.substr(
273         C.Offset - TUEntry.Contributions[TypesIndex].Offset, C.Length));
274     C.Offset = TypesOffset;
275     TypesOffset += C.Length;
276   }
277 }
278 
279 static void addAllTypes(MCStreamer &Out,
280                         MapVector<uint64_t, UnitIndexEntry> &TypeIndexEntries,
281                         MCSection *OutputTypes,
282                         const std::vector<StringRef> &TypesSections,
283                         const UnitIndexEntry &CUEntry, uint32_t &TypesOffset) {
284   for (StringRef Types : TypesSections) {
285     Out.SwitchSection(OutputTypes);
286     uint64_t Offset = 0;
287     DataExtractor Data(Types, true, 0);
288     while (Data.isValidOffset(Offset)) {
289       UnitIndexEntry Entry = CUEntry;
290       // Zero out the debug_info contribution
291       Entry.Contributions[0] = {};
292       auto &C = Entry.Contributions[getContributionIndex(DW_SECT_EXT_TYPES)];
293       C.Offset = TypesOffset;
294       auto PrevOffset = Offset;
295       // Length of the unit, including the 4 byte length field.
296       C.Length = Data.getU32(&Offset) + 4;
297 
298       Data.getU16(&Offset); // Version
299       Data.getU32(&Offset); // Abbrev offset
300       Data.getU8(&Offset);  // Address size
301       auto Signature = Data.getU64(&Offset);
302       Offset = PrevOffset + C.Length;
303 
304       auto P = TypeIndexEntries.insert(std::make_pair(Signature, Entry));
305       if (!P.second)
306         continue;
307 
308       Out.emitBytes(Types.substr(PrevOffset, C.Length));
309       TypesOffset += C.Length;
310     }
311   }
312 }
313 
314 static void
315 writeIndexTable(MCStreamer &Out, ArrayRef<unsigned> ContributionOffsets,
316                 const MapVector<uint64_t, UnitIndexEntry> &IndexEntries,
317                 uint32_t DWARFUnitIndex::Entry::SectionContribution::*Field) {
318   for (const auto &E : IndexEntries)
319     for (size_t i = 0; i != array_lengthof(E.second.Contributions); ++i)
320       if (ContributionOffsets[i])
321         Out.emitIntValue(E.second.Contributions[i].*Field, 4);
322 }
323 
324 static void
325 writeIndex(MCStreamer &Out, MCSection *Section,
326            ArrayRef<unsigned> ContributionOffsets,
327            const MapVector<uint64_t, UnitIndexEntry> &IndexEntries) {
328   if (IndexEntries.empty())
329     return;
330 
331   unsigned Columns = 0;
332   for (auto &C : ContributionOffsets)
333     if (C)
334       ++Columns;
335 
336   std::vector<unsigned> Buckets(NextPowerOf2(3 * IndexEntries.size() / 2));
337   uint64_t Mask = Buckets.size() - 1;
338   size_t i = 0;
339   for (const auto &P : IndexEntries) {
340     auto S = P.first;
341     auto H = S & Mask;
342     auto HP = ((S >> 32) & Mask) | 1;
343     while (Buckets[H]) {
344       assert(S != IndexEntries.begin()[Buckets[H] - 1].first &&
345              "Duplicate unit");
346       H = (H + HP) & Mask;
347     }
348     Buckets[H] = i + 1;
349     ++i;
350   }
351 
352   Out.SwitchSection(Section);
353   Out.emitIntValue(2, 4);                   // Version
354   Out.emitIntValue(Columns, 4);             // Columns
355   Out.emitIntValue(IndexEntries.size(), 4); // Num Units
356   Out.emitIntValue(Buckets.size(), 4);      // Num Buckets
357 
358   // Write the signatures.
359   for (const auto &I : Buckets)
360     Out.emitIntValue(I ? IndexEntries.begin()[I - 1].first : 0, 8);
361 
362   // Write the indexes.
363   for (const auto &I : Buckets)
364     Out.emitIntValue(I, 4);
365 
366   // Write the column headers (which sections will appear in the table)
367   for (size_t i = 0; i != ContributionOffsets.size(); ++i)
368     if (ContributionOffsets[i])
369       Out.emitIntValue(getOnDiskSectionId(i), 4);
370 
371   // Write the offsets.
372   writeIndexTable(Out, ContributionOffsets, IndexEntries,
373                   &DWARFUnitIndex::Entry::SectionContribution::Offset);
374 
375   // Write the lengths.
376   writeIndexTable(Out, ContributionOffsets, IndexEntries,
377                   &DWARFUnitIndex::Entry::SectionContribution::Length);
378 }
379 
380 static std::string buildDWODescription(StringRef Name, StringRef DWPName,
381                                        StringRef DWOName) {
382   std::string Text = "\'";
383   Text += Name;
384   Text += '\'';
385   if (!DWPName.empty()) {
386     Text += " (from ";
387     if (!DWOName.empty()) {
388       Text += '\'';
389       Text += DWOName;
390       Text += "' in ";
391     }
392     Text += '\'';
393     Text += DWPName;
394     Text += "')";
395   }
396   return Text;
397 }
398 
399 static Error createError(StringRef Name, Error E) {
400   return make_error<DWPError>(
401       ("failure while decompressing compressed section: '" + Name + "', " +
402        llvm::toString(std::move(E)))
403           .str());
404 }
405 
406 static Error
407 handleCompressedSection(std::deque<SmallString<32>> &UncompressedSections,
408                         StringRef &Name, StringRef &Contents) {
409   if (!Decompressor::isGnuStyle(Name))
410     return Error::success();
411 
412   Expected<Decompressor> Dec =
413       Decompressor::create(Name, Contents, false /*IsLE*/, false /*Is64Bit*/);
414   if (!Dec)
415     return createError(Name, Dec.takeError());
416 
417   UncompressedSections.emplace_back();
418   if (Error E = Dec->resizeAndDecompress(UncompressedSections.back()))
419     return createError(Name, std::move(E));
420 
421   Name = Name.substr(2); // Drop ".z"
422   Contents = UncompressedSections.back();
423   return Error::success();
424 }
425 
426 static Error handleSection(
427     const StringMap<std::pair<MCSection *, DWARFSectionKind>> &KnownSections,
428     const MCSection *StrSection, const MCSection *StrOffsetSection,
429     const MCSection *TypesSection, const MCSection *CUIndexSection,
430     const MCSection *TUIndexSection, const SectionRef &Section, MCStreamer &Out,
431     std::deque<SmallString<32>> &UncompressedSections,
432     uint32_t (&ContributionOffsets)[8], UnitIndexEntry &CurEntry,
433     StringRef &CurStrSection, StringRef &CurStrOffsetSection,
434     std::vector<StringRef> &CurTypesSection, StringRef &InfoSection,
435     StringRef &AbbrevSection, StringRef &CurCUIndexSection,
436     StringRef &CurTUIndexSection) {
437   if (Section.isBSS())
438     return Error::success();
439 
440   if (Section.isVirtual())
441     return Error::success();
442 
443   Expected<StringRef> NameOrErr = Section.getName();
444   if (!NameOrErr)
445     return NameOrErr.takeError();
446   StringRef Name = *NameOrErr;
447 
448   Expected<StringRef> ContentsOrErr = Section.getContents();
449   if (!ContentsOrErr)
450     return ContentsOrErr.takeError();
451   StringRef Contents = *ContentsOrErr;
452 
453   if (auto Err = handleCompressedSection(UncompressedSections, Name, Contents))
454     return Err;
455 
456   Name = Name.substr(Name.find_first_not_of("._"));
457 
458   auto SectionPair = KnownSections.find(Name);
459   if (SectionPair == KnownSections.end())
460     return Error::success();
461 
462   if (DWARFSectionKind Kind = SectionPair->second.second) {
463     auto Index = getContributionIndex(Kind);
464     if (Kind != DW_SECT_EXT_TYPES) {
465       CurEntry.Contributions[Index].Offset = ContributionOffsets[Index];
466       ContributionOffsets[Index] +=
467           (CurEntry.Contributions[Index].Length = Contents.size());
468     }
469 
470     switch (Kind) {
471     case DW_SECT_INFO:
472       InfoSection = Contents;
473       break;
474     case DW_SECT_ABBREV:
475       AbbrevSection = Contents;
476       break;
477     default:
478       break;
479     }
480   }
481 
482   MCSection *OutSection = SectionPair->second.first;
483   if (OutSection == StrOffsetSection)
484     CurStrOffsetSection = Contents;
485   else if (OutSection == StrSection)
486     CurStrSection = Contents;
487   else if (OutSection == TypesSection)
488     CurTypesSection.push_back(Contents);
489   else if (OutSection == CUIndexSection)
490     CurCUIndexSection = Contents;
491   else if (OutSection == TUIndexSection)
492     CurTUIndexSection = Contents;
493   else {
494     Out.SwitchSection(OutSection);
495     Out.emitBytes(Contents);
496   }
497   return Error::success();
498 }
499 
500 static Error
501 buildDuplicateError(const std::pair<uint64_t, UnitIndexEntry> &PrevE,
502                     const CompileUnitIdentifiers &ID, StringRef DWPName) {
503   return make_error<DWPError>(
504       std::string("duplicate DWO ID (") + utohexstr(PrevE.first) + ") in " +
505       buildDWODescription(PrevE.second.Name, PrevE.second.DWPName,
506                           PrevE.second.DWOName) +
507       " and " + buildDWODescription(ID.Name, DWPName, ID.DWOName));
508 }
509 
510 static Expected<SmallVector<std::string, 16>>
511 getDWOFilenames(StringRef ExecFilename) {
512   auto ErrOrObj = object::ObjectFile::createObjectFile(ExecFilename);
513   if (!ErrOrObj)
514     return ErrOrObj.takeError();
515 
516   const ObjectFile &Obj = *ErrOrObj.get().getBinary();
517   std::unique_ptr<DWARFContext> DWARFCtx = DWARFContext::create(Obj);
518 
519   SmallVector<std::string, 16> DWOPaths;
520   for (const auto &CU : DWARFCtx->compile_units()) {
521     const DWARFDie &Die = CU->getUnitDIE();
522     std::string DWOName = dwarf::toString(
523         Die.find({dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}), "");
524     if (DWOName.empty())
525       continue;
526     std::string DWOCompDir =
527         dwarf::toString(Die.find(dwarf::DW_AT_comp_dir), "");
528     if (!DWOCompDir.empty()) {
529       SmallString<16> DWOPath(std::move(DWOName));
530       sys::fs::make_absolute(DWOCompDir, DWOPath);
531       DWOPaths.emplace_back(DWOPath.data(), DWOPath.size());
532     } else {
533       DWOPaths.push_back(std::move(DWOName));
534     }
535   }
536   return std::move(DWOPaths);
537 }
538 
539 static Error write(MCStreamer &Out, ArrayRef<std::string> Inputs) {
540   const auto &MCOFI = *Out.getContext().getObjectFileInfo();
541   MCSection *const StrSection = MCOFI.getDwarfStrDWOSection();
542   MCSection *const StrOffsetSection = MCOFI.getDwarfStrOffDWOSection();
543   MCSection *const TypesSection = MCOFI.getDwarfTypesDWOSection();
544   MCSection *const CUIndexSection = MCOFI.getDwarfCUIndexSection();
545   MCSection *const TUIndexSection = MCOFI.getDwarfTUIndexSection();
546   const StringMap<std::pair<MCSection *, DWARFSectionKind>> KnownSections = {
547       {"debug_info.dwo", {MCOFI.getDwarfInfoDWOSection(), DW_SECT_INFO}},
548       {"debug_types.dwo", {MCOFI.getDwarfTypesDWOSection(), DW_SECT_EXT_TYPES}},
549       {"debug_str_offsets.dwo", {StrOffsetSection, DW_SECT_STR_OFFSETS}},
550       {"debug_str.dwo", {StrSection, static_cast<DWARFSectionKind>(0)}},
551       {"debug_loc.dwo", {MCOFI.getDwarfLocDWOSection(), DW_SECT_EXT_LOC}},
552       {"debug_line.dwo", {MCOFI.getDwarfLineDWOSection(), DW_SECT_LINE}},
553       {"debug_abbrev.dwo", {MCOFI.getDwarfAbbrevDWOSection(), DW_SECT_ABBREV}},
554       {"debug_cu_index", {CUIndexSection, static_cast<DWARFSectionKind>(0)}},
555       {"debug_tu_index", {TUIndexSection, static_cast<DWARFSectionKind>(0)}}};
556 
557   MapVector<uint64_t, UnitIndexEntry> IndexEntries;
558   MapVector<uint64_t, UnitIndexEntry> TypeIndexEntries;
559 
560   uint32_t ContributionOffsets[8] = {};
561 
562   DWPStringPool Strings(Out, StrSection);
563 
564   SmallVector<OwningBinary<object::ObjectFile>, 128> Objects;
565   Objects.reserve(Inputs.size());
566 
567   std::deque<SmallString<32>> UncompressedSections;
568 
569   for (const auto &Input : Inputs) {
570     auto ErrOrObj = object::ObjectFile::createObjectFile(Input);
571     if (!ErrOrObj)
572       return ErrOrObj.takeError();
573 
574     auto &Obj = *ErrOrObj->getBinary();
575     Objects.push_back(std::move(*ErrOrObj));
576 
577     UnitIndexEntry CurEntry = {};
578 
579     StringRef CurStrSection;
580     StringRef CurStrOffsetSection;
581     std::vector<StringRef> CurTypesSection;
582     StringRef InfoSection;
583     StringRef AbbrevSection;
584     StringRef CurCUIndexSection;
585     StringRef CurTUIndexSection;
586 
587     for (const auto &Section : Obj.sections())
588       if (auto Err = handleSection(
589               KnownSections, StrSection, StrOffsetSection, TypesSection,
590               CUIndexSection, TUIndexSection, Section, Out,
591               UncompressedSections, ContributionOffsets, CurEntry,
592               CurStrSection, CurStrOffsetSection, CurTypesSection, InfoSection,
593               AbbrevSection, CurCUIndexSection, CurTUIndexSection))
594         return Err;
595 
596     if (InfoSection.empty())
597       continue;
598 
599     writeStringsAndOffsets(Out, Strings, StrOffsetSection, CurStrSection,
600                            CurStrOffsetSection);
601 
602     if (CurCUIndexSection.empty()) {
603       Expected<CompileUnitIdentifiers> EID = getCUIdentifiers(
604           AbbrevSection, InfoSection, CurStrOffsetSection, CurStrSection);
605       if (!EID)
606         return createFileError(Input, EID.takeError());
607       const auto &ID = *EID;
608       auto P = IndexEntries.insert(std::make_pair(ID.Signature, CurEntry));
609       if (!P.second)
610         return buildDuplicateError(*P.first, ID, "");
611       P.first->second.Name = ID.Name;
612       P.first->second.DWOName = ID.DWOName;
613       addAllTypes(Out, TypeIndexEntries, TypesSection, CurTypesSection,
614                   CurEntry,
615                   ContributionOffsets[getContributionIndex(DW_SECT_EXT_TYPES)]);
616       continue;
617     }
618 
619     DWARFUnitIndex CUIndex(DW_SECT_INFO);
620     DataExtractor CUIndexData(CurCUIndexSection, Obj.isLittleEndian(), 0);
621     if (!CUIndex.parse(CUIndexData))
622       return make_error<DWPError>("failed to parse cu_index");
623     if (CUIndex.getVersion() != 2)
624       return make_error<DWPError>(
625           "unsupported cu_index version: " + utostr(CUIndex.getVersion()) +
626           " (only version 2 is supported)");
627 
628     for (const DWARFUnitIndex::Entry &E : CUIndex.getRows()) {
629       auto *I = E.getContributions();
630       if (!I)
631         continue;
632       auto P = IndexEntries.insert(std::make_pair(E.getSignature(), CurEntry));
633       Expected<CompileUnitIdentifiers> EID = getCUIdentifiers(
634           getSubsection(AbbrevSection, E, DW_SECT_ABBREV),
635           getSubsection(InfoSection, E, DW_SECT_INFO),
636           getSubsection(CurStrOffsetSection, E, DW_SECT_STR_OFFSETS),
637           CurStrSection);
638       if (!EID)
639         return createFileError(Input, EID.takeError());
640       const auto &ID = *EID;
641       if (!P.second)
642         return buildDuplicateError(*P.first, ID, Input);
643       auto &NewEntry = P.first->second;
644       NewEntry.Name = ID.Name;
645       NewEntry.DWOName = ID.DWOName;
646       NewEntry.DWPName = Input;
647       for (auto Kind : CUIndex.getColumnKinds()) {
648         if (!isSupportedSectionKind(Kind))
649           continue;
650         auto &C = NewEntry.Contributions[getContributionIndex(Kind)];
651         C.Offset += I->Offset;
652         C.Length = I->Length;
653         ++I;
654       }
655     }
656 
657     if (!CurTypesSection.empty()) {
658       if (CurTypesSection.size() != 1)
659         return make_error<DWPError>("multiple type unit sections in .dwp file");
660       DWARFUnitIndex TUIndex(DW_SECT_EXT_TYPES);
661       DataExtractor TUIndexData(CurTUIndexSection, Obj.isLittleEndian(), 0);
662       if (!TUIndex.parse(TUIndexData))
663         return make_error<DWPError>("failed to parse tu_index");
664       if (TUIndex.getVersion() != 2)
665         return make_error<DWPError>(
666             "unsupported tu_index version: " + utostr(TUIndex.getVersion()) +
667             " (only version 2 is supported)");
668 
669       addAllTypesFromDWP(
670           Out, TypeIndexEntries, TUIndex, TypesSection, CurTypesSection.front(),
671           CurEntry,
672           ContributionOffsets[getContributionIndex(DW_SECT_EXT_TYPES)]);
673     }
674   }
675 
676   // Lie about there being no info contributions so the TU index only includes
677   // the type unit contribution
678   ContributionOffsets[0] = 0;
679   writeIndex(Out, MCOFI.getDwarfTUIndexSection(), ContributionOffsets,
680              TypeIndexEntries);
681 
682   // Lie about the type contribution
683   ContributionOffsets[getContributionIndex(DW_SECT_EXT_TYPES)] = 0;
684   // Unlie about the info contribution
685   ContributionOffsets[0] = 1;
686 
687   writeIndex(Out, MCOFI.getDwarfCUIndexSection(), ContributionOffsets,
688              IndexEntries);
689 
690   return Error::success();
691 }
692 
693 static int error(const Twine &Error, const Twine &Context) {
694   errs() << Twine("while processing ") + Context + ":\n";
695   errs() << Twine("error: ") + Error + "\n";
696   return 1;
697 }
698 
699 static Expected<Triple> readTargetTriple(StringRef FileName) {
700   auto ErrOrObj = object::ObjectFile::createObjectFile(FileName);
701   if (!ErrOrObj)
702     return ErrOrObj.takeError();
703 
704   return ErrOrObj->getBinary()->makeTriple();
705 }
706 
707 int main(int argc, char **argv) {
708   InitLLVM X(argc, argv);
709 
710   cl::ParseCommandLineOptions(argc, argv, "merge split dwarf (.dwo) files\n");
711 
712   llvm::InitializeAllTargetInfos();
713   llvm::InitializeAllTargetMCs();
714   llvm::InitializeAllTargets();
715   llvm::InitializeAllAsmPrinters();
716 
717   std::vector<std::string> DWOFilenames = InputFiles;
718   for (const auto &ExecFilename : ExecFilenames) {
719     auto DWOs = getDWOFilenames(ExecFilename);
720     if (!DWOs) {
721       logAllUnhandledErrors(DWOs.takeError(), WithColor::error());
722       return 1;
723     }
724     DWOFilenames.insert(DWOFilenames.end(),
725                         std::make_move_iterator(DWOs->begin()),
726                         std::make_move_iterator(DWOs->end()));
727   }
728 
729   if (DWOFilenames.empty())
730     return 0;
731 
732   std::string ErrorStr;
733   StringRef Context = "dwarf streamer init";
734 
735   auto ErrOrTriple = readTargetTriple(DWOFilenames.front());
736   if (!ErrOrTriple) {
737     logAllUnhandledErrors(ErrOrTriple.takeError(), WithColor::error());
738     return 1;
739   }
740 
741   // Get the target.
742   const Target *TheTarget =
743       TargetRegistry::lookupTarget("", *ErrOrTriple, ErrorStr);
744   if (!TheTarget)
745     return error(ErrorStr, Context);
746   std::string TripleName = ErrOrTriple->getTriple();
747 
748   // Create all the MC Objects.
749   std::unique_ptr<MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TripleName));
750   if (!MRI)
751     return error(Twine("no register info for target ") + TripleName, Context);
752 
753   MCTargetOptions MCOptions = llvm::mc::InitMCTargetOptionsFromFlags();
754   std::unique_ptr<MCAsmInfo> MAI(
755       TheTarget->createMCAsmInfo(*MRI, TripleName, MCOptions));
756   if (!MAI)
757     return error("no asm info for target " + TripleName, Context);
758 
759   MCObjectFileInfo MOFI;
760   MCContext MC(MAI.get(), MRI.get(), &MOFI);
761   MOFI.InitMCObjectFileInfo(*ErrOrTriple, /*PIC*/ false, MC);
762 
763   std::unique_ptr<MCSubtargetInfo> MSTI(
764       TheTarget->createMCSubtargetInfo(TripleName, "", ""));
765   if (!MSTI)
766     return error("no subtarget info for target " + TripleName, Context);
767 
768   MCTargetOptions Options;
769   auto MAB = TheTarget->createMCAsmBackend(*MSTI, *MRI, Options);
770   if (!MAB)
771     return error("no asm backend for target " + TripleName, Context);
772 
773   std::unique_ptr<MCInstrInfo> MII(TheTarget->createMCInstrInfo());
774   if (!MII)
775     return error("no instr info info for target " + TripleName, Context);
776 
777   MCCodeEmitter *MCE = TheTarget->createMCCodeEmitter(*MII, *MRI, MC);
778   if (!MCE)
779     return error("no code emitter for target " + TripleName, Context);
780 
781   // Create the output file.
782   std::error_code EC;
783   ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_None);
784   Optional<buffer_ostream> BOS;
785   raw_pwrite_stream *OS;
786   if (EC)
787     return error(Twine(OutputFilename) + ": " + EC.message(), Context);
788   if (OutFile.os().supportsSeeking()) {
789     OS = &OutFile.os();
790   } else {
791     BOS.emplace(OutFile.os());
792     OS = BOS.getPointer();
793   }
794 
795   std::unique_ptr<MCStreamer> MS(TheTarget->createMCObjectStreamer(
796       *ErrOrTriple, MC, std::unique_ptr<MCAsmBackend>(MAB),
797       MAB->createObjectWriter(*OS), std::unique_ptr<MCCodeEmitter>(MCE), *MSTI,
798       MCOptions.MCRelaxAll, MCOptions.MCIncrementalLinkerCompatible,
799       /*DWARFMustBeAtTheEnd*/ false));
800   if (!MS)
801     return error("no object streamer for target " + TripleName, Context);
802 
803   if (auto Err = write(*MS, DWOFilenames)) {
804     logAllUnhandledErrors(std::move(Err), WithColor::error());
805     return 1;
806   }
807 
808   MS->Finish();
809   OutFile.keep();
810   return 0;
811 }
812