1 //===- tools/dsymutil/DwarfLinker.cpp - Dwarf debug info linker -----------===//
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "BinaryHolder.h"
13 #include "llvm/ADT/IntervalMap.h"
14 #include "llvm/ADT/StringMap.h"
15 #include "llvm/ADT/STLExtras.h"
16 #include "llvm/CodeGen/AsmPrinter.h"
17 #include "llvm/CodeGen/DIE.h"
18 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
19 #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h"
20 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
21 #include "llvm/MC/MCAsmBackend.h"
22 #include "llvm/MC/MCAsmInfo.h"
23 #include "llvm/MC/MCContext.h"
24 #include "llvm/MC/MCCodeEmitter.h"
25 #include "llvm/MC/MCDwarf.h"
26 #include "llvm/MC/MCInstrInfo.h"
27 #include "llvm/MC/MCObjectFileInfo.h"
28 #include "llvm/MC/MCRegisterInfo.h"
29 #include "llvm/MC/MCStreamer.h"
30 #include "llvm/Object/MachO.h"
31 #include "llvm/Support/Dwarf.h"
32 #include "llvm/Support/LEB128.h"
33 #include "llvm/Support/TargetRegistry.h"
34 #include "llvm/Target/TargetMachine.h"
35 #include "llvm/Target/TargetOptions.h"
44 void warn(const Twine &Warning, const Twine &Context) {
45 errs() << Twine("while processing ") + Context + ":\n";
46 errs() << Twine("warning: ") + Warning + "\n";
49 bool error(const Twine &Error, const Twine &Context) {
50 errs() << Twine("while processing ") + Context + ":\n";
51 errs() << Twine("error: ") + Error + "\n";
55 template <typename KeyT, typename ValT>
56 using HalfOpenIntervalMap =
57 IntervalMap<KeyT, ValT, IntervalMapImpl::NodeSizer<KeyT, ValT>::LeafSize,
58 IntervalMapHalfOpenInfo<KeyT>>;
60 typedef HalfOpenIntervalMap<uint64_t, int64_t> FunctionIntervals;
62 /// \brief Stores all information relating to a compile unit, be it in
63 /// its original instance in the object file to its brand new cloned
64 /// and linked DIE tree.
67 /// \brief Information gathered about a DIE in the object file.
69 int64_t AddrAdjust; ///< Address offset to apply to the described entity.
70 DIE *Clone; ///< Cloned version of that DIE.
71 uint32_t ParentIdx; ///< The index of this DIE's parent.
72 bool Keep; ///< Is the DIE part of the linked output?
73 bool InDebugMap; ///< Was this DIE's entity found in the map?
76 CompileUnit(DWARFUnit &OrigUnit, unsigned ID)
77 : OrigUnit(OrigUnit), ID(ID), LowPc(UINT64_MAX), HighPc(0), RangeAlloc(),
78 Ranges(RangeAlloc), UnitRangeAttribute(nullptr) {
79 Info.resize(OrigUnit.getNumDIEs());
82 CompileUnit(CompileUnit &&RHS)
83 : OrigUnit(RHS.OrigUnit), Info(std::move(RHS.Info)),
84 CUDie(std::move(RHS.CUDie)), StartOffset(RHS.StartOffset),
85 NextUnitOffset(RHS.NextUnitOffset), RangeAlloc(), Ranges(RangeAlloc) {
86 // The CompileUnit container has been 'reserve()'d with the right
87 // size. We cannot move the IntervalMap anyway.
88 llvm_unreachable("CompileUnits should not be moved.");
91 DWARFUnit &getOrigUnit() const { return OrigUnit; }
93 unsigned getUniqueID() const { return ID; }
95 DIE *getOutputUnitDIE() const { return CUDie.get(); }
96 void setOutputUnitDIE(DIE *Die) { CUDie.reset(Die); }
98 DIEInfo &getInfo(unsigned Idx) { return Info[Idx]; }
99 const DIEInfo &getInfo(unsigned Idx) const { return Info[Idx]; }
101 uint64_t getStartOffset() const { return StartOffset; }
102 uint64_t getNextUnitOffset() const { return NextUnitOffset; }
103 void setStartOffset(uint64_t DebugInfoSize) { StartOffset = DebugInfoSize; }
105 uint64_t getLowPc() const { return LowPc; }
106 uint64_t getHighPc() const { return HighPc; }
108 DIEInteger *getUnitRangesAttribute() const { return UnitRangeAttribute; }
109 const FunctionIntervals &getFunctionRanges() const { return Ranges; }
110 const std::vector<DIEInteger *> &getRangesAttributes() const {
111 return RangeAttributes;
114 const std::vector<std::pair<DIEInteger *, int64_t>> &
115 getLocationAttributes() const {
116 return LocationAttributes;
119 /// \brief Compute the end offset for this unit. Must be
120 /// called after the CU's DIEs have been cloned.
121 /// \returns the next unit offset (which is also the current
122 /// debug_info section size).
123 uint64_t computeNextUnitOffset();
125 /// \brief Keep track of a forward reference to DIE \p Die in \p
126 /// RefUnit by \p Attr. The attribute should be fixed up later to
127 /// point to the absolute offset of \p Die in the debug_info section.
128 void noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
131 /// \brief Apply all fixups recored by noteForwardReference().
132 void fixupForwardReferences();
134 /// \brief Add a function range [\p LowPC, \p HighPC) that is
135 /// relocatad by applying offset \p PCOffset.
136 void addFunctionRange(uint64_t LowPC, uint64_t HighPC, int64_t PCOffset);
138 /// \brief Keep track of a DW_AT_range attribute that we will need to
140 void noteRangeAttribute(const DIE &Die, DIEInteger *Attr);
142 /// \brief Keep track of a location attribute pointing to a location
143 /// list in the debug_loc section.
144 void noteLocationAttribute(DIEInteger *Attr, int64_t PcOffset);
149 std::vector<DIEInfo> Info; ///< DIE info indexed by DIE index.
150 std::unique_ptr<DIE> CUDie; ///< Root of the linked DIE tree.
152 uint64_t StartOffset;
153 uint64_t NextUnitOffset;
158 /// \brief A list of attributes to fixup with the absolute offset of
159 /// a DIE in the debug_info section.
161 /// The offsets for the attributes in this array couldn't be set while
162 /// cloning because for cross-cu forward refences the target DIE's
163 /// offset isn't known you emit the reference attribute.
164 std::vector<std::tuple<DIE *, const CompileUnit *, DIEInteger *>>
165 ForwardDIEReferences;
167 FunctionIntervals::Allocator RangeAlloc;
168 /// \brief The ranges in that interval map are the PC ranges for
169 /// functions in this unit, associated with the PC offset to apply
170 /// to the addresses to get the linked address.
171 FunctionIntervals Ranges;
173 /// \brief DW_AT_ranges attributes to patch after we have gathered
174 /// all the unit's function addresses.
176 std::vector<DIEInteger *> RangeAttributes;
177 DIEInteger *UnitRangeAttribute;
180 /// \brief Location attributes that need to be transfered from th
181 /// original debug_loc section to the liked one. They are stored
182 /// along with the PC offset that is to be applied to their
183 /// function's address.
184 std::vector<std::pair<DIEInteger *, int64_t>> LocationAttributes;
187 uint64_t CompileUnit::computeNextUnitOffset() {
188 NextUnitOffset = StartOffset + 11 /* Header size */;
189 // The root DIE might be null, meaning that the Unit had nothing to
190 // contribute to the linked output. In that case, we will emit the
191 // unit header without any actual DIE.
193 NextUnitOffset += CUDie->getSize();
194 return NextUnitOffset;
197 /// \brief Keep track of a forward cross-cu reference from this unit
198 /// to \p Die that lives in \p RefUnit.
199 void CompileUnit::noteForwardReference(DIE *Die, const CompileUnit *RefUnit,
201 ForwardDIEReferences.emplace_back(Die, RefUnit, Attr);
204 /// \brief Apply all fixups recorded by noteForwardReference().
205 void CompileUnit::fixupForwardReferences() {
206 for (const auto &Ref : ForwardDIEReferences) {
208 const CompileUnit *RefUnit;
210 std::tie(RefDie, RefUnit, Attr) = Ref;
211 Attr->setValue(RefDie->getOffset() + RefUnit->getStartOffset());
215 void CompileUnit::addFunctionRange(uint64_t FuncLowPc, uint64_t FuncHighPc,
217 Ranges.insert(FuncLowPc, FuncHighPc, PcOffset);
218 this->LowPc = std::min(LowPc, FuncLowPc + PcOffset);
219 this->HighPc = std::max(HighPc, FuncHighPc + PcOffset);
222 void CompileUnit::noteRangeAttribute(const DIE &Die, DIEInteger *Attr) {
223 if (Die.getTag() != dwarf::DW_TAG_compile_unit)
224 RangeAttributes.push_back(Attr);
226 UnitRangeAttribute = Attr;
229 void CompileUnit::noteLocationAttribute(DIEInteger *Attr, int64_t PcOffset) {
230 LocationAttributes.emplace_back(Attr, PcOffset);
233 /// \brief A string table that doesn't need relocations.
235 /// We are doing a final link, no need for a string table that
236 /// has relocation entries for every reference to it. This class
237 /// provides this ablitity by just associating offsets with
239 class NonRelocatableStringpool {
241 /// \brief Entries are stored into the StringMap and simply linked
242 /// together through the second element of this pair in order to
243 /// keep track of insertion order.
244 typedef StringMap<std::pair<uint32_t, StringMapEntryBase *>, BumpPtrAllocator>
247 NonRelocatableStringpool()
248 : CurrentEndOffset(0), Sentinel(0), Last(&Sentinel) {
249 // Legacy dsymutil puts an empty string at the start of the line
254 /// \brief Get the offset of string \p S in the string table. This
255 /// can insert a new element or return the offset of a preexisitng
257 uint32_t getStringOffset(StringRef S);
259 /// \brief Get permanent storage for \p S (but do not necessarily
260 /// emit \p S in the output section).
261 /// \returns The StringRef that points to permanent storage to use
262 /// in place of \p S.
263 StringRef internString(StringRef S);
265 // \brief Return the first entry of the string table.
266 const MapTy::MapEntryTy *getFirstEntry() const {
267 return getNextEntry(&Sentinel);
270 // \brief Get the entry following \p E in the string table or null
271 // if \p E was the last entry.
272 const MapTy::MapEntryTy *getNextEntry(const MapTy::MapEntryTy *E) const {
273 return static_cast<const MapTy::MapEntryTy *>(E->getValue().second);
276 uint64_t getSize() { return CurrentEndOffset; }
280 uint32_t CurrentEndOffset;
281 MapTy::MapEntryTy Sentinel, *Last;
284 /// \brief Get the offset of string \p S in the string table. This
285 /// can insert a new element or return the offset of a preexisitng
287 uint32_t NonRelocatableStringpool::getStringOffset(StringRef S) {
288 if (S.empty() && !Strings.empty())
291 std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr);
295 // A non-empty string can't be at offset 0, so if we have an entry
296 // with a 0 offset, it must be a previously interned string.
297 std::tie(It, Inserted) = Strings.insert(std::make_pair(S, Entry));
298 if (Inserted || It->getValue().first == 0) {
299 // Set offset and chain at the end of the entries list.
300 It->getValue().first = CurrentEndOffset;
301 CurrentEndOffset += S.size() + 1; // +1 for the '\0'.
302 Last->getValue().second = &*It;
305 return It->getValue().first;
308 /// \brief Put \p S into the StringMap so that it gets permanent
309 /// storage, but do not actually link it in the chain of elements
310 /// that go into the output section. A latter call to
311 /// getStringOffset() with the same string will chain it though.
312 StringRef NonRelocatableStringpool::internString(StringRef S) {
313 std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr);
314 auto InsertResult = Strings.insert(std::make_pair(S, Entry));
315 return InsertResult.first->getKey();
318 /// \brief The Dwarf streaming logic
320 /// All interactions with the MC layer that is used to build the debug
321 /// information binary representation are handled in this class.
322 class DwarfStreamer {
323 /// \defgroup MCObjects MC layer objects constructed by the streamer
325 std::unique_ptr<MCRegisterInfo> MRI;
326 std::unique_ptr<MCAsmInfo> MAI;
327 std::unique_ptr<MCObjectFileInfo> MOFI;
328 std::unique_ptr<MCContext> MC;
329 MCAsmBackend *MAB; // Owned by MCStreamer
330 std::unique_ptr<MCInstrInfo> MII;
331 std::unique_ptr<MCSubtargetInfo> MSTI;
332 MCCodeEmitter *MCE; // Owned by MCStreamer
333 MCStreamer *MS; // Owned by AsmPrinter
334 std::unique_ptr<TargetMachine> TM;
335 std::unique_ptr<AsmPrinter> Asm;
338 /// \brief the file we stream the linked Dwarf to.
339 std::unique_ptr<raw_fd_ostream> OutFile;
341 uint32_t RangesSectionSize;
342 uint32_t LocSectionSize;
343 uint32_t LineSectionSize;
346 /// \brief Actually create the streamer and the ouptut file.
348 /// This could be done directly in the constructor, but it feels
349 /// more natural to handle errors through return value.
350 bool init(Triple TheTriple, StringRef OutputFilename);
352 /// \brief Dump the file to the disk.
355 AsmPrinter &getAsmPrinter() const { return *Asm; }
357 /// \brief Set the current output section to debug_info and change
358 /// the MC Dwarf version to \p DwarfVersion.
359 void switchToDebugInfoSection(unsigned DwarfVersion);
361 /// \brief Emit the compilation unit header for \p Unit in the
362 /// debug_info section.
364 /// As a side effect, this also switches the current Dwarf version
365 /// of the MC layer to the one of U.getOrigUnit().
366 void emitCompileUnitHeader(CompileUnit &Unit);
368 /// \brief Recursively emit the DIE tree rooted at \p Die.
369 void emitDIE(DIE &Die);
371 /// \brief Emit the abbreviation table \p Abbrevs to the
372 /// debug_abbrev section.
373 void emitAbbrevs(const std::vector<DIEAbbrev *> &Abbrevs);
375 /// \brief Emit the string table described by \p Pool.
376 void emitStrings(const NonRelocatableStringpool &Pool);
378 /// \brief Emit debug_ranges for \p FuncRange by translating the
379 /// original \p Entries.
380 void emitRangesEntries(
381 int64_t UnitPcOffset, uint64_t OrigLowPc,
382 FunctionIntervals::const_iterator FuncRange,
383 const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
384 unsigned AddressSize);
386 /// \brief Emit debug_aranges entries for \p Unit and if \p
387 /// DoRangesSection is true, also emit the debug_ranges entries for
388 /// the DW_TAG_compile_unit's DW_AT_ranges attribute.
389 void emitUnitRangesEntries(CompileUnit &Unit, bool DoRangesSection);
391 uint32_t getRangesSectionSize() const { return RangesSectionSize; }
393 /// \brief Emit the debug_loc contribution for \p Unit by copying
394 /// the entries from \p Dwarf and offseting them. Update the
395 /// location attributes to point to the new entries.
396 void emitLocationsForUnit(const CompileUnit &Unit, DWARFContext &Dwarf);
398 /// \brief Emit the line table described in \p Rows into the
399 /// debug_line section.
400 void emitLineTableForUnit(StringRef PrologueBytes, unsigned MinInstLength,
401 std::vector<DWARFDebugLine::Row> &Rows,
402 unsigned AdddressSize);
404 uint32_t getLineSectionSize() const { return LineSectionSize; }
407 bool DwarfStreamer::init(Triple TheTriple, StringRef OutputFilename) {
408 std::string ErrorStr;
409 std::string TripleName;
410 StringRef Context = "dwarf streamer init";
413 const Target *TheTarget =
414 TargetRegistry::lookupTarget(TripleName, TheTriple, ErrorStr);
416 return error(ErrorStr, Context);
417 TripleName = TheTriple.getTriple();
419 // Create all the MC Objects.
420 MRI.reset(TheTarget->createMCRegInfo(TripleName));
422 return error(Twine("no register info for target ") + TripleName, Context);
424 MAI.reset(TheTarget->createMCAsmInfo(*MRI, TripleName));
426 return error("no asm info for target " + TripleName, Context);
428 MOFI.reset(new MCObjectFileInfo);
429 MC.reset(new MCContext(MAI.get(), MRI.get(), MOFI.get()));
430 MOFI->InitMCObjectFileInfo(TripleName, Reloc::Default, CodeModel::Default,
433 MAB = TheTarget->createMCAsmBackend(*MRI, TripleName, "");
435 return error("no asm backend for target " + TripleName, Context);
437 MII.reset(TheTarget->createMCInstrInfo());
439 return error("no instr info info for target " + TripleName, Context);
441 MSTI.reset(TheTarget->createMCSubtargetInfo(TripleName, "", ""));
443 return error("no subtarget info for target " + TripleName, Context);
445 MCE = TheTarget->createMCCodeEmitter(*MII, *MRI, *MC);
447 return error("no code emitter for target " + TripleName, Context);
449 // Create the output file.
452 llvm::make_unique<raw_fd_ostream>(OutputFilename, EC, sys::fs::F_None);
454 return error(Twine(OutputFilename) + ": " + EC.message(), Context);
456 MS = TheTarget->createMCObjectStreamer(TripleName, *MC, *MAB, *OutFile, MCE,
459 return error("no object streamer for target " + TripleName, Context);
461 // Finally create the AsmPrinter we'll use to emit the DIEs.
462 TM.reset(TheTarget->createTargetMachine(TripleName, "", "", TargetOptions()));
464 return error("no target machine for target " + TripleName, Context);
466 Asm.reset(TheTarget->createAsmPrinter(*TM, std::unique_ptr<MCStreamer>(MS)));
468 return error("no asm printer for target " + TripleName, Context);
470 RangesSectionSize = 0;
477 bool DwarfStreamer::finish() {
482 /// \brief Set the current output section to debug_info and change
483 /// the MC Dwarf version to \p DwarfVersion.
484 void DwarfStreamer::switchToDebugInfoSection(unsigned DwarfVersion) {
485 MS->SwitchSection(MOFI->getDwarfInfoSection());
486 MC->setDwarfVersion(DwarfVersion);
489 /// \brief Emit the compilation unit header for \p Unit in the
490 /// debug_info section.
492 /// A Dwarf scetion header is encoded as:
493 /// uint32_t Unit length (omiting this field)
495 /// uint32_t Abbreviation table offset
496 /// uint8_t Address size
498 /// Leading to a total of 11 bytes.
499 void DwarfStreamer::emitCompileUnitHeader(CompileUnit &Unit) {
500 unsigned Version = Unit.getOrigUnit().getVersion();
501 switchToDebugInfoSection(Version);
503 // Emit size of content not including length itself. The size has
504 // already been computed in CompileUnit::computeOffsets(). Substract
505 // 4 to that size to account for the length field.
506 Asm->EmitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset() - 4);
507 Asm->EmitInt16(Version);
508 // We share one abbreviations table across all units so it's always at the
509 // start of the section.
511 Asm->EmitInt8(Unit.getOrigUnit().getAddressByteSize());
514 /// \brief Emit the \p Abbrevs array as the shared abbreviation table
515 /// for the linked Dwarf file.
516 void DwarfStreamer::emitAbbrevs(const std::vector<DIEAbbrev *> &Abbrevs) {
517 MS->SwitchSection(MOFI->getDwarfAbbrevSection());
518 Asm->emitDwarfAbbrevs(Abbrevs);
521 /// \brief Recursively emit the DIE tree rooted at \p Die.
522 void DwarfStreamer::emitDIE(DIE &Die) {
523 MS->SwitchSection(MOFI->getDwarfInfoSection());
524 Asm->emitDwarfDIE(Die);
527 /// \brief Emit the debug_str section stored in \p Pool.
528 void DwarfStreamer::emitStrings(const NonRelocatableStringpool &Pool) {
529 Asm->OutStreamer.SwitchSection(MOFI->getDwarfStrSection());
530 for (auto *Entry = Pool.getFirstEntry(); Entry;
531 Entry = Pool.getNextEntry(Entry))
532 Asm->OutStreamer.EmitBytes(
533 StringRef(Entry->getKey().data(), Entry->getKey().size() + 1));
536 /// \brief Emit the debug_range section contents for \p FuncRange by
537 /// translating the original \p Entries. The debug_range section
538 /// format is totally trivial, consisting just of pairs of address
539 /// sized addresses describing the ranges.
540 void DwarfStreamer::emitRangesEntries(
541 int64_t UnitPcOffset, uint64_t OrigLowPc,
542 FunctionIntervals::const_iterator FuncRange,
543 const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries,
544 unsigned AddressSize) {
545 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
547 // Offset each range by the right amount.
548 int64_t PcOffset = FuncRange.value() + UnitPcOffset;
549 for (const auto &Range : Entries) {
550 if (Range.isBaseAddressSelectionEntry(AddressSize)) {
551 warn("unsupported base address selection operation",
552 "emitting debug_ranges");
555 // Do not emit empty ranges.
556 if (Range.StartAddress == Range.EndAddress)
559 // All range entries should lie in the function range.
560 if (!(Range.StartAddress + OrigLowPc >= FuncRange.start() &&
561 Range.EndAddress + OrigLowPc <= FuncRange.stop()))
562 warn("inconsistent range data.", "emitting debug_ranges");
563 MS->EmitIntValue(Range.StartAddress + PcOffset, AddressSize);
564 MS->EmitIntValue(Range.EndAddress + PcOffset, AddressSize);
565 RangesSectionSize += 2 * AddressSize;
568 // Add the terminator entry.
569 MS->EmitIntValue(0, AddressSize);
570 MS->EmitIntValue(0, AddressSize);
571 RangesSectionSize += 2 * AddressSize;
574 /// \brief Emit the debug_aranges contribution of a unit and
575 /// if \p DoDebugRanges is true the debug_range contents for a
576 /// compile_unit level DW_AT_ranges attribute (Which are basically the
577 /// same thing with a different base address).
578 /// Just aggregate all the ranges gathered inside that unit.
579 void DwarfStreamer::emitUnitRangesEntries(CompileUnit &Unit,
580 bool DoDebugRanges) {
581 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
582 // Gather the ranges in a vector, so that we can simplify them. The
583 // IntervalMap will have coalesced the non-linked ranges, but here
584 // we want to coalesce the linked addresses.
585 std::vector<std::pair<uint64_t, uint64_t>> Ranges;
586 const auto &FunctionRanges = Unit.getFunctionRanges();
587 for (auto Range = FunctionRanges.begin(), End = FunctionRanges.end();
588 Range != End; ++Range)
589 Ranges.push_back(std::make_pair(Range.start() + Range.value(),
590 Range.stop() + Range.value()));
592 // The object addresses where sorted, but again, the linked
593 // addresses might end up in a different order.
594 std::sort(Ranges.begin(), Ranges.end());
596 if (!Ranges.empty()) {
597 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfARangesSection());
599 MCSymbol *BeginLabel = Asm->GetTempSymbol("Barange", Unit.getUniqueID());
600 MCSymbol *EndLabel = Asm->GetTempSymbol("Earange", Unit.getUniqueID());
602 unsigned HeaderSize =
603 sizeof(int32_t) + // Size of contents (w/o this field
604 sizeof(int16_t) + // DWARF ARange version number
605 sizeof(int32_t) + // Offset of CU in the .debug_info section
606 sizeof(int8_t) + // Pointer Size (in bytes)
607 sizeof(int8_t); // Segment Size (in bytes)
609 unsigned TupleSize = AddressSize * 2;
610 unsigned Padding = OffsetToAlignment(HeaderSize, TupleSize);
612 Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Arange length
613 Asm->OutStreamer.EmitLabel(BeginLabel);
614 Asm->EmitInt16(dwarf::DW_ARANGES_VERSION); // Version number
615 Asm->EmitInt32(Unit.getStartOffset()); // Corresponding unit's offset
616 Asm->EmitInt8(AddressSize); // Address size
617 Asm->EmitInt8(0); // Segment size
619 Asm->OutStreamer.EmitFill(Padding, 0x0);
621 for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End;
623 uint64_t RangeStart = Range->first;
624 MS->EmitIntValue(RangeStart, AddressSize);
625 while ((Range + 1) != End && Range->second == (Range + 1)->first)
627 MS->EmitIntValue(Range->second - RangeStart, AddressSize);
631 Asm->OutStreamer.EmitIntValue(0, AddressSize);
632 Asm->OutStreamer.EmitIntValue(0, AddressSize);
633 Asm->OutStreamer.EmitLabel(EndLabel);
639 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection());
640 // Offset each range by the right amount.
641 int64_t PcOffset = -Unit.getLowPc();
642 // Emit coalesced ranges.
643 for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End; ++Range) {
644 MS->EmitIntValue(Range->first + PcOffset, AddressSize);
645 while (Range + 1 != End && Range->second == (Range + 1)->first)
647 MS->EmitIntValue(Range->second + PcOffset, AddressSize);
648 RangesSectionSize += 2 * AddressSize;
651 // Add the terminator entry.
652 MS->EmitIntValue(0, AddressSize);
653 MS->EmitIntValue(0, AddressSize);
654 RangesSectionSize += 2 * AddressSize;
657 /// \brief Emit location lists for \p Unit and update attribtues to
658 /// point to the new entries.
659 void DwarfStreamer::emitLocationsForUnit(const CompileUnit &Unit,
660 DWARFContext &Dwarf) {
661 const std::vector<std::pair<DIEInteger *, int64_t>> &Attributes =
662 Unit.getLocationAttributes();
664 if (Attributes.empty())
667 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLocSection());
669 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
670 const DWARFSection &InputSec = Dwarf.getLocSection();
671 DataExtractor Data(InputSec.Data, Dwarf.isLittleEndian(), AddressSize);
672 DWARFUnit &OrigUnit = Unit.getOrigUnit();
673 const auto *OrigUnitDie = OrigUnit.getCompileUnitDIE(false);
674 int64_t UnitPcOffset = 0;
675 uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress(
676 &OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
677 if (OrigLowPc != -1ULL)
678 UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc();
680 for (const auto &Attr : Attributes) {
681 uint32_t Offset = Attr.first->getValue();
682 Attr.first->setValue(LocSectionSize);
683 // This is the quantity to add to the old location address to get
684 // the correct address for the new one.
685 int64_t LocPcOffset = Attr.second + UnitPcOffset;
686 while (Data.isValidOffset(Offset)) {
687 uint64_t Low = Data.getUnsigned(&Offset, AddressSize);
688 uint64_t High = Data.getUnsigned(&Offset, AddressSize);
689 LocSectionSize += 2 * AddressSize;
690 if (Low == 0 && High == 0) {
691 Asm->OutStreamer.EmitIntValue(0, AddressSize);
692 Asm->OutStreamer.EmitIntValue(0, AddressSize);
695 Asm->OutStreamer.EmitIntValue(Low + LocPcOffset, AddressSize);
696 Asm->OutStreamer.EmitIntValue(High + LocPcOffset, AddressSize);
697 uint64_t Length = Data.getU16(&Offset);
698 Asm->OutStreamer.EmitIntValue(Length, 2);
699 // Just copy the bytes over.
700 Asm->OutStreamer.EmitBytes(
701 StringRef(InputSec.Data.substr(Offset, Length)));
703 LocSectionSize += Length + 2;
708 void DwarfStreamer::emitLineTableForUnit(StringRef PrologueBytes,
709 unsigned MinInstLength,
710 std::vector<DWARFDebugLine::Row> &Rows,
711 unsigned PointerSize) {
712 // Switch to the section where the table will be emitted into.
713 MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection());
714 MCSymbol *LineStartSym = MC->CreateTempSymbol();
715 MCSymbol *LineEndSym = MC->CreateTempSymbol();
717 // The first 4 bytes is the total length of the information for this
718 // compilation unit (not including these 4 bytes for the length).
719 Asm->EmitLabelDifference(LineEndSym, LineStartSym, 4);
720 Asm->OutStreamer.EmitLabel(LineStartSym);
722 MS->EmitBytes(PrologueBytes);
723 LineSectionSize += PrologueBytes.size() + 4;
725 SmallString<16> EncodingBuffer;
726 raw_svector_ostream EncodingOS(EncodingBuffer);
729 // We only have the dummy entry, dsymutil emits an entry with a 0
730 // address in that case.
731 MCDwarfLineAddr::Encode(*MC, INT64_MAX, 0, EncodingOS);
732 MS->EmitBytes(EncodingOS.str());
733 LineSectionSize += EncodingBuffer.size();
734 EncodingBuffer.resize(0);
735 MS->EmitLabel(LineEndSym);
739 // Line table state machine fields
740 unsigned FileNum = 1;
741 unsigned LastLine = 1;
743 unsigned IsStatement = 1;
745 uint64_t Address = -1ULL;
747 unsigned RowsSinceLastSequence = 0;
749 for (unsigned Idx = 0; Idx < Rows.size(); ++Idx) {
750 auto &Row = Rows[Idx];
752 int64_t AddressDelta;
753 if (Address == -1ULL) {
754 MS->EmitIntValue(dwarf::DW_LNS_extended_op, 1);
755 MS->EmitULEB128IntValue(PointerSize + 1);
756 MS->EmitIntValue(dwarf::DW_LNE_set_address, 1);
757 MS->EmitIntValue(Row.Address, PointerSize);
758 LineSectionSize += 2 + PointerSize + getULEB128Size(PointerSize + 1);
761 AddressDelta = (Row.Address - Address) / MinInstLength;
764 // FIXME: code copied and transfromed from
765 // MCDwarf.cpp::EmitDwarfLineTable. We should find a way to share
766 // this code, but the current compatibility requirement with
767 // classic dsymutil makes it hard. Revisit that once this
768 // requirement is dropped.
770 if (FileNum != Row.File) {
772 MS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
773 MS->EmitULEB128IntValue(FileNum);
774 LineSectionSize += 1 + getULEB128Size(FileNum);
776 if (Column != Row.Column) {
778 MS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
779 MS->EmitULEB128IntValue(Column);
780 LineSectionSize += 1 + getULEB128Size(Column);
783 // FIXME: We should handle the discriminator here, but dsymutil
784 // doesn' consider it, thus ignore it for now.
786 if (Isa != Row.Isa) {
788 MS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
789 MS->EmitULEB128IntValue(Isa);
790 LineSectionSize += 1 + getULEB128Size(Isa);
792 if (IsStatement != Row.IsStmt) {
793 IsStatement = Row.IsStmt;
794 MS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
795 LineSectionSize += 1;
797 if (Row.BasicBlock) {
798 MS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
799 LineSectionSize += 1;
802 if (Row.PrologueEnd) {
803 MS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
804 LineSectionSize += 1;
807 if (Row.EpilogueBegin) {
808 MS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
809 LineSectionSize += 1;
812 int64_t LineDelta = int64_t(Row.Line) - LastLine;
813 if (!Row.EndSequence) {
814 MCDwarfLineAddr::Encode(*MC, LineDelta, AddressDelta, EncodingOS);
815 MS->EmitBytes(EncodingOS.str());
816 LineSectionSize += EncodingBuffer.size();
817 EncodingBuffer.resize(0);
818 Address = Row.Address;
820 RowsSinceLastSequence++;
823 MS->EmitIntValue(dwarf::DW_LNS_advance_line, 1);
824 MS->EmitSLEB128IntValue(LineDelta);
825 LineSectionSize += 1 + getSLEB128Size(LineDelta);
828 MS->EmitIntValue(dwarf::DW_LNS_advance_pc, 1);
829 MS->EmitULEB128IntValue(AddressDelta);
830 LineSectionSize += 1 + getULEB128Size(AddressDelta);
832 MCDwarfLineAddr::Encode(*MC, INT64_MAX, 0, EncodingOS);
833 MS->EmitBytes(EncodingOS.str());
834 LineSectionSize += EncodingBuffer.size();
835 EncodingBuffer.resize(0);
838 LastLine = FileNum = IsStatement = 1;
839 RowsSinceLastSequence = Column = Isa = 0;
843 if (RowsSinceLastSequence) {
844 MCDwarfLineAddr::Encode(*MC, INT64_MAX, 0, EncodingOS);
845 MS->EmitBytes(EncodingOS.str());
846 LineSectionSize += EncodingBuffer.size();
847 EncodingBuffer.resize(0);
850 MS->EmitLabel(LineEndSym);
853 /// \brief The core of the Dwarf linking logic.
855 /// The link of the dwarf information from the object files will be
856 /// driven by the selection of 'root DIEs', which are DIEs that
857 /// describe variables or functions that are present in the linked
858 /// binary (and thus have entries in the debug map). All the debug
859 /// information that will be linked (the DIEs, but also the line
860 /// tables, ranges, ...) is derived from that set of root DIEs.
862 /// The root DIEs are identified because they contain relocations that
863 /// correspond to a debug map entry at specific places (the low_pc for
864 /// a function, the location for a variable). These relocations are
865 /// called ValidRelocs in the DwarfLinker and are gathered as a very
866 /// first step when we start processing a DebugMapObject.
869 DwarfLinker(StringRef OutputFilename, const LinkOptions &Options)
870 : OutputFilename(OutputFilename), Options(Options),
871 BinHolder(Options.Verbose) {}
874 for (auto *Abbrev : Abbreviations)
878 /// \brief Link the contents of the DebugMap.
879 bool link(const DebugMap &);
882 /// \brief Called at the start of a debug object link.
883 void startDebugObject(DWARFContext &, DebugMapObject &);
885 /// \brief Called at the end of a debug object link.
886 void endDebugObject();
888 /// \defgroup FindValidRelocations Translate debug map into a list
889 /// of relevant relocations
896 const DebugMapObject::DebugMapEntry *Mapping;
898 ValidReloc(uint32_t Offset, uint32_t Size, uint64_t Addend,
899 const DebugMapObject::DebugMapEntry *Mapping)
900 : Offset(Offset), Size(Size), Addend(Addend), Mapping(Mapping) {}
902 bool operator<(const ValidReloc &RHS) const { return Offset < RHS.Offset; }
905 /// \brief The valid relocations for the current DebugMapObject.
906 /// This vector is sorted by relocation offset.
907 std::vector<ValidReloc> ValidRelocs;
909 /// \brief Index into ValidRelocs of the next relocation to
910 /// consider. As we walk the DIEs in acsending file offset and as
911 /// ValidRelocs is sorted by file offset, keeping this index
912 /// uptodate is all we have to do to have a cheap lookup during the
913 /// root DIE selection and during DIE cloning.
914 unsigned NextValidReloc;
916 bool findValidRelocsInDebugInfo(const object::ObjectFile &Obj,
917 const DebugMapObject &DMO);
919 bool findValidRelocs(const object::SectionRef &Section,
920 const object::ObjectFile &Obj,
921 const DebugMapObject &DMO);
923 void findValidRelocsMachO(const object::SectionRef &Section,
924 const object::MachOObjectFile &Obj,
925 const DebugMapObject &DMO);
928 /// \defgroup FindRootDIEs Find DIEs corresponding to debug map entries.
931 /// \brief Recursively walk the \p DIE tree and look for DIEs to
932 /// keep. Store that information in \p CU's DIEInfo.
933 void lookForDIEsToKeep(const DWARFDebugInfoEntryMinimal &DIE,
934 const DebugMapObject &DMO, CompileUnit &CU,
937 /// \brief Flags passed to DwarfLinker::lookForDIEsToKeep
939 TF_Keep = 1 << 0, ///< Mark the traversed DIEs as kept.
940 TF_InFunctionScope = 1 << 1, ///< Current scope is a fucntion scope.
941 TF_DependencyWalk = 1 << 2, ///< Walking the dependencies of a kept DIE.
942 TF_ParentWalk = 1 << 3, ///< Walking up the parents of a kept DIE.
945 /// \brief Mark the passed DIE as well as all the ones it depends on
947 void keepDIEAndDenpendencies(const DWARFDebugInfoEntryMinimal &DIE,
948 CompileUnit::DIEInfo &MyInfo,
949 const DebugMapObject &DMO, CompileUnit &CU,
952 unsigned shouldKeepDIE(const DWARFDebugInfoEntryMinimal &DIE,
953 CompileUnit &Unit, CompileUnit::DIEInfo &MyInfo,
956 unsigned shouldKeepVariableDIE(const DWARFDebugInfoEntryMinimal &DIE,
958 CompileUnit::DIEInfo &MyInfo, unsigned Flags);
960 unsigned shouldKeepSubprogramDIE(const DWARFDebugInfoEntryMinimal &DIE,
962 CompileUnit::DIEInfo &MyInfo,
965 bool hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
966 CompileUnit::DIEInfo &Info);
969 /// \defgroup Linking Methods used to link the debug information
972 /// \brief Recursively clone \p InputDIE into an tree of DIE objects
973 /// where useless (as decided by lookForDIEsToKeep()) bits have been
974 /// stripped out and addresses have been rewritten according to the
977 /// \param OutOffset is the offset the cloned DIE in the output
979 /// \param PCOffset (while cloning a function scope) is the offset
980 /// applied to the entry point of the function to get the linked address.
982 /// \returns the root of the cloned tree.
983 DIE *cloneDIE(const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &U,
984 int64_t PCOffset, uint32_t OutOffset);
986 typedef DWARFAbbreviationDeclaration::AttributeSpec AttributeSpec;
988 /// \brief Information gathered and exchanged between the various
989 /// clone*Attributes helpers about the attributes of a particular DIE.
990 struct AttributesInfo {
991 uint64_t OrigHighPc; ///< Value of AT_high_pc in the input DIE
992 int64_t PCOffset; ///< Offset to apply to PC addresses inside a function.
994 AttributesInfo() : OrigHighPc(0), PCOffset(0) {}
997 /// \brief Helper for cloneDIE.
998 unsigned cloneAttribute(DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE,
999 CompileUnit &U, const DWARFFormValue &Val,
1000 const AttributeSpec AttrSpec, unsigned AttrSize,
1001 AttributesInfo &AttrInfo);
1003 /// \brief Helper for cloneDIE.
1004 unsigned cloneStringAttribute(DIE &Die, AttributeSpec AttrSpec,
1005 const DWARFFormValue &Val, const DWARFUnit &U);
1007 /// \brief Helper for cloneDIE.
1009 cloneDieReferenceAttribute(DIE &Die,
1010 const DWARFDebugInfoEntryMinimal &InputDIE,
1011 AttributeSpec AttrSpec, unsigned AttrSize,
1012 const DWARFFormValue &Val, CompileUnit &Unit);
1014 /// \brief Helper for cloneDIE.
1015 unsigned cloneBlockAttribute(DIE &Die, AttributeSpec AttrSpec,
1016 const DWARFFormValue &Val, unsigned AttrSize);
1018 /// \brief Helper for cloneDIE.
1019 unsigned cloneAddressAttribute(DIE &Die, AttributeSpec AttrSpec,
1020 const DWARFFormValue &Val,
1021 const CompileUnit &Unit, AttributesInfo &Info);
1023 /// \brief Helper for cloneDIE.
1024 unsigned cloneScalarAttribute(DIE &Die,
1025 const DWARFDebugInfoEntryMinimal &InputDIE,
1026 CompileUnit &U, AttributeSpec AttrSpec,
1027 const DWARFFormValue &Val, unsigned AttrSize,
1028 const AttributesInfo &Info);
1030 /// \brief Helper for cloneDIE.
1031 bool applyValidRelocs(MutableArrayRef<char> Data, uint32_t BaseOffset,
1032 bool isLittleEndian);
1034 /// \brief Assign an abbreviation number to \p Abbrev
1035 void AssignAbbrev(DIEAbbrev &Abbrev);
1037 /// \brief FoldingSet that uniques the abbreviations.
1038 FoldingSet<DIEAbbrev> AbbreviationsSet;
1039 /// \brief Storage for the unique Abbreviations.
1040 /// This is passed to AsmPrinter::emitDwarfAbbrevs(), thus it cannot
1041 /// be changed to a vecot of unique_ptrs.
1042 std::vector<DIEAbbrev *> Abbreviations;
1044 /// \brief Compute and emit debug_ranges section for \p Unit, and
1045 /// patch the attributes referencing it.
1046 void patchRangesForUnit(const CompileUnit &Unit, DWARFContext &Dwarf) const;
1048 /// \brief Generate and emit the DW_AT_ranges attribute for a
1049 /// compile_unit if it had one.
1050 void generateUnitRanges(CompileUnit &Unit) const;
1052 /// \brief Extract the line tables fromt he original dwarf, extract
1053 /// the relevant parts according to the linked function ranges and
1054 /// emit the result in the debug_line section.
1055 void patchLineTableForUnit(CompileUnit &Unit, DWARFContext &OrigDwarf);
1057 /// \brief DIELoc objects that need to be destructed (but not freed!).
1058 std::vector<DIELoc *> DIELocs;
1059 /// \brief DIEBlock objects that need to be destructed (but not freed!).
1060 std::vector<DIEBlock *> DIEBlocks;
1061 /// \brief Allocator used for all the DIEValue objects.
1062 BumpPtrAllocator DIEAlloc;
1065 /// \defgroup Helpers Various helper methods.
1068 const DWARFDebugInfoEntryMinimal *
1069 resolveDIEReference(DWARFFormValue &RefValue, const DWARFUnit &Unit,
1070 const DWARFDebugInfoEntryMinimal &DIE,
1071 CompileUnit *&ReferencedCU);
1073 CompileUnit *getUnitForOffset(unsigned Offset);
1075 void reportWarning(const Twine &Warning, const DWARFUnit *Unit = nullptr,
1076 const DWARFDebugInfoEntryMinimal *DIE = nullptr) const;
1078 bool createStreamer(Triple TheTriple, StringRef OutputFilename);
1082 std::string OutputFilename;
1083 LinkOptions Options;
1084 BinaryHolder BinHolder;
1085 std::unique_ptr<DwarfStreamer> Streamer;
1087 /// The units of the current debug map object.
1088 std::vector<CompileUnit> Units;
1090 /// The debug map object curently under consideration.
1091 DebugMapObject *CurrentDebugObject;
1093 /// \brief The Dwarf string pool
1094 NonRelocatableStringpool StringPool;
1096 /// \brief This map is keyed by the entry PC of functions in that
1097 /// debug object and the associated value is a pair storing the
1098 /// corresponding end PC and the offset to apply to get the linked
1101 /// See startDebugObject() for a more complete description of its use.
1102 std::map<uint64_t, std::pair<uint64_t, int64_t>> Ranges;
1105 /// \brief Similar to DWARFUnitSection::getUnitForOffset(), but
1106 /// returning our CompileUnit object instead.
1107 CompileUnit *DwarfLinker::getUnitForOffset(unsigned Offset) {
1109 std::upper_bound(Units.begin(), Units.end(), Offset,
1110 [](uint32_t LHS, const CompileUnit &RHS) {
1111 return LHS < RHS.getOrigUnit().getNextUnitOffset();
1113 return CU != Units.end() ? &*CU : nullptr;
1116 /// \brief Resolve the DIE attribute reference that has been
1117 /// extracted in \p RefValue. The resulting DIE migh be in another
1118 /// CompileUnit which is stored into \p ReferencedCU.
1119 /// \returns null if resolving fails for any reason.
1120 const DWARFDebugInfoEntryMinimal *DwarfLinker::resolveDIEReference(
1121 DWARFFormValue &RefValue, const DWARFUnit &Unit,
1122 const DWARFDebugInfoEntryMinimal &DIE, CompileUnit *&RefCU) {
1123 assert(RefValue.isFormClass(DWARFFormValue::FC_Reference));
1124 uint64_t RefOffset = *RefValue.getAsReference(&Unit);
1126 if ((RefCU = getUnitForOffset(RefOffset)))
1127 if (const auto *RefDie = RefCU->getOrigUnit().getDIEForOffset(RefOffset))
1130 reportWarning("could not find referenced DIE", &Unit, &DIE);
1134 /// \brief Report a warning to the user, optionaly including
1135 /// information about a specific \p DIE related to the warning.
1136 void DwarfLinker::reportWarning(const Twine &Warning, const DWARFUnit *Unit,
1137 const DWARFDebugInfoEntryMinimal *DIE) const {
1138 StringRef Context = "<debug map>";
1139 if (CurrentDebugObject)
1140 Context = CurrentDebugObject->getObjectFilename();
1141 warn(Warning, Context);
1143 if (!Options.Verbose || !DIE)
1146 errs() << " in DIE:\n";
1147 DIE->dump(errs(), const_cast<DWARFUnit *>(Unit), 0 /* RecurseDepth */,
1151 bool DwarfLinker::createStreamer(Triple TheTriple, StringRef OutputFilename) {
1152 if (Options.NoOutput)
1155 Streamer = llvm::make_unique<DwarfStreamer>();
1156 return Streamer->init(TheTriple, OutputFilename);
1159 /// \brief Recursive helper to gather the child->parent relationships in the
1160 /// original compile unit.
1161 static void gatherDIEParents(const DWARFDebugInfoEntryMinimal *DIE,
1162 unsigned ParentIdx, CompileUnit &CU) {
1163 unsigned MyIdx = CU.getOrigUnit().getDIEIndex(DIE);
1164 CU.getInfo(MyIdx).ParentIdx = ParentIdx;
1166 if (DIE->hasChildren())
1167 for (auto *Child = DIE->getFirstChild(); Child && !Child->isNULL();
1168 Child = Child->getSibling())
1169 gatherDIEParents(Child, MyIdx, CU);
1172 static bool dieNeedsChildrenToBeMeaningful(uint32_t Tag) {
1176 case dwarf::DW_TAG_subprogram:
1177 case dwarf::DW_TAG_lexical_block:
1178 case dwarf::DW_TAG_subroutine_type:
1179 case dwarf::DW_TAG_structure_type:
1180 case dwarf::DW_TAG_class_type:
1181 case dwarf::DW_TAG_union_type:
1184 llvm_unreachable("Invalid Tag");
1187 void DwarfLinker::startDebugObject(DWARFContext &Dwarf, DebugMapObject &Obj) {
1188 Units.reserve(Dwarf.getNumCompileUnits());
1190 // Iterate over the debug map entries and put all the ones that are
1191 // functions (because they have a size) into the Ranges map. This
1192 // map is very similar to the FunctionRanges that are stored in each
1193 // unit, with 2 notable differences:
1194 // - obviously this one is global, while the other ones are per-unit.
1195 // - this one contains not only the functions described in the DIE
1196 // tree, but also the ones that are only in the debug map.
1197 // The latter information is required to reproduce dsymutil's logic
1198 // while linking line tables. The cases where this information
1199 // matters look like bugs that need to be investigated, but for now
1200 // we need to reproduce dsymutil's behavior.
1201 // FIXME: Once we understood exactly if that information is needed,
1202 // maybe totally remove this (or try to use it to do a real
1203 // -gline-tables-only on Darwin.
1204 for (const auto &Entry : Obj.symbols()) {
1205 const auto &Mapping = Entry.getValue();
1207 Ranges[Mapping.ObjectAddress] = std::make_pair(
1208 Mapping.ObjectAddress + Mapping.Size,
1209 int64_t(Mapping.BinaryAddress) - Mapping.ObjectAddress);
1213 void DwarfLinker::endDebugObject() {
1215 ValidRelocs.clear();
1218 for (auto *Block : DIEBlocks)
1220 for (auto *Loc : DIELocs)
1228 /// \brief Iterate over the relocations of the given \p Section and
1229 /// store the ones that correspond to debug map entries into the
1230 /// ValidRelocs array.
1231 void DwarfLinker::findValidRelocsMachO(const object::SectionRef &Section,
1232 const object::MachOObjectFile &Obj,
1233 const DebugMapObject &DMO) {
1235 Section.getContents(Contents);
1236 DataExtractor Data(Contents, Obj.isLittleEndian(), 0);
1238 for (const object::RelocationRef &Reloc : Section.relocations()) {
1239 object::DataRefImpl RelocDataRef = Reloc.getRawDataRefImpl();
1240 MachO::any_relocation_info MachOReloc = Obj.getRelocation(RelocDataRef);
1241 unsigned RelocSize = 1 << Obj.getAnyRelocationLength(MachOReloc);
1243 if ((RelocSize != 4 && RelocSize != 8) || Reloc.getOffset(Offset64)) {
1244 reportWarning(" unsupported relocation in debug_info section.");
1247 uint32_t Offset = Offset64;
1248 // Mach-o uses REL relocations, the addend is at the relocation offset.
1249 uint64_t Addend = Data.getUnsigned(&Offset, RelocSize);
1251 auto Sym = Reloc.getSymbol();
1252 if (Sym != Obj.symbol_end()) {
1253 StringRef SymbolName;
1254 if (Sym->getName(SymbolName)) {
1255 reportWarning("error getting relocation symbol name.");
1258 if (const auto *Mapping = DMO.lookupSymbol(SymbolName))
1259 ValidRelocs.emplace_back(Offset64, RelocSize, Addend, Mapping);
1260 } else if (const auto *Mapping = DMO.lookupObjectAddress(Addend)) {
1261 // Do not store the addend. The addend was the address of the
1262 // symbol in the object file, the address in the binary that is
1263 // stored in the debug map doesn't need to be offseted.
1264 ValidRelocs.emplace_back(Offset64, RelocSize, 0, Mapping);
1269 /// \brief Dispatch the valid relocation finding logic to the
1270 /// appropriate handler depending on the object file format.
1271 bool DwarfLinker::findValidRelocs(const object::SectionRef &Section,
1272 const object::ObjectFile &Obj,
1273 const DebugMapObject &DMO) {
1274 // Dispatch to the right handler depending on the file type.
1275 if (auto *MachOObj = dyn_cast<object::MachOObjectFile>(&Obj))
1276 findValidRelocsMachO(Section, *MachOObj, DMO);
1278 reportWarning(Twine("unsupported object file type: ") + Obj.getFileName());
1280 if (ValidRelocs.empty())
1283 // Sort the relocations by offset. We will walk the DIEs linearly in
1284 // the file, this allows us to just keep an index in the relocation
1285 // array that we advance during our walk, rather than resorting to
1286 // some associative container. See DwarfLinker::NextValidReloc.
1287 std::sort(ValidRelocs.begin(), ValidRelocs.end());
1291 /// \brief Look for relocations in the debug_info section that match
1292 /// entries in the debug map. These relocations will drive the Dwarf
1293 /// link by indicating which DIEs refer to symbols present in the
1295 /// \returns wether there are any valid relocations in the debug info.
1296 bool DwarfLinker::findValidRelocsInDebugInfo(const object::ObjectFile &Obj,
1297 const DebugMapObject &DMO) {
1298 // Find the debug_info section.
1299 for (const object::SectionRef &Section : Obj.sections()) {
1300 StringRef SectionName;
1301 Section.getName(SectionName);
1302 SectionName = SectionName.substr(SectionName.find_first_not_of("._"));
1303 if (SectionName != "debug_info")
1305 return findValidRelocs(Section, Obj, DMO);
1310 /// \brief Checks that there is a relocation against an actual debug
1311 /// map entry between \p StartOffset and \p NextOffset.
1313 /// This function must be called with offsets in strictly ascending
1314 /// order because it never looks back at relocations it already 'went past'.
1315 /// \returns true and sets Info.InDebugMap if it is the case.
1316 bool DwarfLinker::hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset,
1317 CompileUnit::DIEInfo &Info) {
1318 assert(NextValidReloc == 0 ||
1319 StartOffset > ValidRelocs[NextValidReloc - 1].Offset);
1320 if (NextValidReloc >= ValidRelocs.size())
1323 uint64_t RelocOffset = ValidRelocs[NextValidReloc].Offset;
1325 // We might need to skip some relocs that we didn't consider. For
1326 // example the high_pc of a discarded DIE might contain a reloc that
1327 // is in the list because it actually corresponds to the start of a
1328 // function that is in the debug map.
1329 while (RelocOffset < StartOffset && NextValidReloc < ValidRelocs.size() - 1)
1330 RelocOffset = ValidRelocs[++NextValidReloc].Offset;
1332 if (RelocOffset < StartOffset || RelocOffset >= EndOffset)
1335 const auto &ValidReloc = ValidRelocs[NextValidReloc++];
1336 if (Options.Verbose)
1337 outs() << "Found valid debug map entry: " << ValidReloc.Mapping->getKey()
1338 << " " << format("\t%016" PRIx64 " => %016" PRIx64,
1339 ValidReloc.Mapping->getValue().ObjectAddress,
1340 ValidReloc.Mapping->getValue().BinaryAddress);
1342 Info.AddrAdjust = int64_t(ValidReloc.Mapping->getValue().BinaryAddress) +
1344 ValidReloc.Mapping->getValue().ObjectAddress;
1345 Info.InDebugMap = true;
1349 /// \brief Get the starting and ending (exclusive) offset for the
1350 /// attribute with index \p Idx descibed by \p Abbrev. \p Offset is
1351 /// supposed to point to the position of the first attribute described
1353 /// \return [StartOffset, EndOffset) as a pair.
1354 static std::pair<uint32_t, uint32_t>
1355 getAttributeOffsets(const DWARFAbbreviationDeclaration *Abbrev, unsigned Idx,
1356 unsigned Offset, const DWARFUnit &Unit) {
1357 DataExtractor Data = Unit.getDebugInfoExtractor();
1359 for (unsigned i = 0; i < Idx; ++i)
1360 DWARFFormValue::skipValue(Abbrev->getFormByIndex(i), Data, &Offset, &Unit);
1362 uint32_t End = Offset;
1363 DWARFFormValue::skipValue(Abbrev->getFormByIndex(Idx), Data, &End, &Unit);
1365 return std::make_pair(Offset, End);
1368 /// \brief Check if a variable describing DIE should be kept.
1369 /// \returns updated TraversalFlags.
1370 unsigned DwarfLinker::shouldKeepVariableDIE(
1371 const DWARFDebugInfoEntryMinimal &DIE, CompileUnit &Unit,
1372 CompileUnit::DIEInfo &MyInfo, unsigned Flags) {
1373 const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
1375 // Global variables with constant value can always be kept.
1376 if (!(Flags & TF_InFunctionScope) &&
1377 Abbrev->findAttributeIndex(dwarf::DW_AT_const_value) != -1U) {
1378 MyInfo.InDebugMap = true;
1379 return Flags | TF_Keep;
1382 uint32_t LocationIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_location);
1383 if (LocationIdx == -1U)
1386 uint32_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
1387 const DWARFUnit &OrigUnit = Unit.getOrigUnit();
1388 uint32_t LocationOffset, LocationEndOffset;
1389 std::tie(LocationOffset, LocationEndOffset) =
1390 getAttributeOffsets(Abbrev, LocationIdx, Offset, OrigUnit);
1392 // See if there is a relocation to a valid debug map entry inside
1393 // this variable's location. The order is important here. We want to
1394 // always check in the variable has a valid relocation, so that the
1395 // DIEInfo is filled. However, we don't want a static variable in a
1396 // function to force us to keep the enclosing function.
1397 if (!hasValidRelocation(LocationOffset, LocationEndOffset, MyInfo) ||
1398 (Flags & TF_InFunctionScope))
1401 if (Options.Verbose)
1402 DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */);
1404 return Flags | TF_Keep;
1407 /// \brief Check if a function describing DIE should be kept.
1408 /// \returns updated TraversalFlags.
1409 unsigned DwarfLinker::shouldKeepSubprogramDIE(
1410 const DWARFDebugInfoEntryMinimal &DIE, CompileUnit &Unit,
1411 CompileUnit::DIEInfo &MyInfo, unsigned Flags) {
1412 const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
1414 Flags |= TF_InFunctionScope;
1416 uint32_t LowPcIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_low_pc);
1417 if (LowPcIdx == -1U)
1420 uint32_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
1421 const DWARFUnit &OrigUnit = Unit.getOrigUnit();
1422 uint32_t LowPcOffset, LowPcEndOffset;
1423 std::tie(LowPcOffset, LowPcEndOffset) =
1424 getAttributeOffsets(Abbrev, LowPcIdx, Offset, OrigUnit);
1427 DIE.getAttributeValueAsAddress(&OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
1428 assert(LowPc != -1ULL && "low_pc attribute is not an address.");
1429 if (LowPc == -1ULL ||
1430 !hasValidRelocation(LowPcOffset, LowPcEndOffset, MyInfo))
1433 if (Options.Verbose)
1434 DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */);
1438 DWARFFormValue HighPcValue;
1439 if (!DIE.getAttributeValue(&OrigUnit, dwarf::DW_AT_high_pc, HighPcValue)) {
1440 reportWarning("Function without high_pc. Range will be discarded.\n",
1446 if (HighPcValue.isFormClass(DWARFFormValue::FC_Address)) {
1447 HighPc = *HighPcValue.getAsAddress(&OrigUnit);
1449 assert(HighPcValue.isFormClass(DWARFFormValue::FC_Constant));
1450 HighPc = LowPc + *HighPcValue.getAsUnsignedConstant();
1453 // Replace the debug map range with a more accurate one.
1454 Ranges[LowPc] = std::make_pair(HighPc, MyInfo.AddrAdjust);
1455 Unit.addFunctionRange(LowPc, HighPc, MyInfo.AddrAdjust);
1459 /// \brief Check if a DIE should be kept.
1460 /// \returns updated TraversalFlags.
1461 unsigned DwarfLinker::shouldKeepDIE(const DWARFDebugInfoEntryMinimal &DIE,
1463 CompileUnit::DIEInfo &MyInfo,
1465 switch (DIE.getTag()) {
1466 case dwarf::DW_TAG_constant:
1467 case dwarf::DW_TAG_variable:
1468 return shouldKeepVariableDIE(DIE, Unit, MyInfo, Flags);
1469 case dwarf::DW_TAG_subprogram:
1470 return shouldKeepSubprogramDIE(DIE, Unit, MyInfo, Flags);
1471 case dwarf::DW_TAG_module:
1472 case dwarf::DW_TAG_imported_module:
1473 case dwarf::DW_TAG_imported_declaration:
1474 case dwarf::DW_TAG_imported_unit:
1475 // We always want to keep these.
1476 return Flags | TF_Keep;
1482 /// \brief Mark the passed DIE as well as all the ones it depends on
1485 /// This function is called by lookForDIEsToKeep on DIEs that are
1486 /// newly discovered to be needed in the link. It recursively calls
1487 /// back to lookForDIEsToKeep while adding TF_DependencyWalk to the
1488 /// TraversalFlags to inform it that it's not doing the primary DIE
1490 void DwarfLinker::keepDIEAndDenpendencies(const DWARFDebugInfoEntryMinimal &DIE,
1491 CompileUnit::DIEInfo &MyInfo,
1492 const DebugMapObject &DMO,
1493 CompileUnit &CU, unsigned Flags) {
1494 const DWARFUnit &Unit = CU.getOrigUnit();
1497 // First mark all the parent chain as kept.
1498 unsigned AncestorIdx = MyInfo.ParentIdx;
1499 while (!CU.getInfo(AncestorIdx).Keep) {
1500 lookForDIEsToKeep(*Unit.getDIEAtIndex(AncestorIdx), DMO, CU,
1501 TF_ParentWalk | TF_Keep | TF_DependencyWalk);
1502 AncestorIdx = CU.getInfo(AncestorIdx).ParentIdx;
1505 // Then we need to mark all the DIEs referenced by this DIE's
1506 // attributes as kept.
1507 DataExtractor Data = Unit.getDebugInfoExtractor();
1508 const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
1509 uint32_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
1511 // Mark all DIEs referenced through atttributes as kept.
1512 for (const auto &AttrSpec : Abbrev->attributes()) {
1513 DWARFFormValue Val(AttrSpec.Form);
1515 if (!Val.isFormClass(DWARFFormValue::FC_Reference)) {
1516 DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset, &Unit);
1520 Val.extractValue(Data, &Offset, &Unit);
1521 CompileUnit *ReferencedCU;
1522 if (const auto *RefDIE = resolveDIEReference(Val, Unit, DIE, ReferencedCU))
1523 lookForDIEsToKeep(*RefDIE, DMO, *ReferencedCU,
1524 TF_Keep | TF_DependencyWalk);
1528 /// \brief Recursively walk the \p DIE tree and look for DIEs to
1529 /// keep. Store that information in \p CU's DIEInfo.
1531 /// This function is the entry point of the DIE selection
1532 /// algorithm. It is expected to walk the DIE tree in file order and
1533 /// (though the mediation of its helper) call hasValidRelocation() on
1534 /// each DIE that might be a 'root DIE' (See DwarfLinker class
1536 /// While walking the dependencies of root DIEs, this function is
1537 /// also called, but during these dependency walks the file order is
1538 /// not respected. The TF_DependencyWalk flag tells us which kind of
1539 /// traversal we are currently doing.
1540 void DwarfLinker::lookForDIEsToKeep(const DWARFDebugInfoEntryMinimal &DIE,
1541 const DebugMapObject &DMO, CompileUnit &CU,
1543 unsigned Idx = CU.getOrigUnit().getDIEIndex(&DIE);
1544 CompileUnit::DIEInfo &MyInfo = CU.getInfo(Idx);
1545 bool AlreadyKept = MyInfo.Keep;
1547 // If the Keep flag is set, we are marking a required DIE's
1548 // dependencies. If our target is already marked as kept, we're all
1550 if ((Flags & TF_DependencyWalk) && AlreadyKept)
1553 // We must not call shouldKeepDIE while called from keepDIEAndDenpendencies,
1554 // because it would screw up the relocation finding logic.
1555 if (!(Flags & TF_DependencyWalk))
1556 Flags = shouldKeepDIE(DIE, CU, MyInfo, Flags);
1558 // If it is a newly kept DIE mark it as well as all its dependencies as kept.
1559 if (!AlreadyKept && (Flags & TF_Keep))
1560 keepDIEAndDenpendencies(DIE, MyInfo, DMO, CU, Flags);
1562 // The TF_ParentWalk flag tells us that we are currently walking up
1563 // the parent chain of a required DIE, and we don't want to mark all
1564 // the children of the parents as kept (consider for example a
1565 // DW_TAG_namespace node in the parent chain). There are however a
1566 // set of DIE types for which we want to ignore that directive and still
1567 // walk their children.
1568 if (dieNeedsChildrenToBeMeaningful(DIE.getTag()))
1569 Flags &= ~TF_ParentWalk;
1571 if (!DIE.hasChildren() || (Flags & TF_ParentWalk))
1574 for (auto *Child = DIE.getFirstChild(); Child && !Child->isNULL();
1575 Child = Child->getSibling())
1576 lookForDIEsToKeep(*Child, DMO, CU, Flags);
1579 /// \brief Assign an abbreviation numer to \p Abbrev.
1581 /// Our DIEs get freed after every DebugMapObject has been processed,
1582 /// thus the FoldingSet we use to unique DIEAbbrevs cannot refer to
1583 /// the instances hold by the DIEs. When we encounter an abbreviation
1584 /// that we don't know, we create a permanent copy of it.
1585 void DwarfLinker::AssignAbbrev(DIEAbbrev &Abbrev) {
1586 // Check the set for priors.
1587 FoldingSetNodeID ID;
1590 DIEAbbrev *InSet = AbbreviationsSet.FindNodeOrInsertPos(ID, InsertToken);
1592 // If it's newly added.
1594 // Assign existing abbreviation number.
1595 Abbrev.setNumber(InSet->getNumber());
1597 // Add to abbreviation list.
1598 Abbreviations.push_back(
1599 new DIEAbbrev(Abbrev.getTag(), Abbrev.hasChildren()));
1600 for (const auto &Attr : Abbrev.getData())
1601 Abbreviations.back()->AddAttribute(Attr.getAttribute(), Attr.getForm());
1602 AbbreviationsSet.InsertNode(Abbreviations.back(), InsertToken);
1603 // Assign the unique abbreviation number.
1604 Abbrev.setNumber(Abbreviations.size());
1605 Abbreviations.back()->setNumber(Abbreviations.size());
1609 /// \brief Clone a string attribute described by \p AttrSpec and add
1611 /// \returns the size of the new attribute.
1612 unsigned DwarfLinker::cloneStringAttribute(DIE &Die, AttributeSpec AttrSpec,
1613 const DWARFFormValue &Val,
1614 const DWARFUnit &U) {
1615 // Switch everything to out of line strings.
1616 const char *String = *Val.getAsCString(&U);
1617 unsigned Offset = StringPool.getStringOffset(String);
1618 Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::DW_FORM_strp,
1619 new (DIEAlloc) DIEInteger(Offset));
1623 /// \brief Clone an attribute referencing another DIE and add
1625 /// \returns the size of the new attribute.
1626 unsigned DwarfLinker::cloneDieReferenceAttribute(
1627 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE,
1628 AttributeSpec AttrSpec, unsigned AttrSize, const DWARFFormValue &Val,
1629 CompileUnit &Unit) {
1630 uint32_t Ref = *Val.getAsReference(&Unit.getOrigUnit());
1631 DIE *NewRefDie = nullptr;
1632 CompileUnit *RefUnit = nullptr;
1633 const DWARFDebugInfoEntryMinimal *RefDie = nullptr;
1635 if (!(RefUnit = getUnitForOffset(Ref)) ||
1636 !(RefDie = RefUnit->getOrigUnit().getDIEForOffset(Ref))) {
1637 const char *AttributeString = dwarf::AttributeString(AttrSpec.Attr);
1638 if (!AttributeString)
1639 AttributeString = "DW_AT_???";
1640 reportWarning(Twine("Missing DIE for ref in attribute ") + AttributeString +
1642 &Unit.getOrigUnit(), &InputDIE);
1646 unsigned Idx = RefUnit->getOrigUnit().getDIEIndex(RefDie);
1647 CompileUnit::DIEInfo &RefInfo = RefUnit->getInfo(Idx);
1648 if (!RefInfo.Clone) {
1649 assert(Ref > InputDIE.getOffset());
1650 // We haven't cloned this DIE yet. Just create an empty one and
1651 // store it. It'll get really cloned when we process it.
1652 RefInfo.Clone = new DIE(dwarf::Tag(RefDie->getTag()));
1654 NewRefDie = RefInfo.Clone;
1656 if (AttrSpec.Form == dwarf::DW_FORM_ref_addr) {
1657 // We cannot currently rely on a DIEEntry to emit ref_addr
1658 // references, because the implementation calls back to DwarfDebug
1659 // to find the unit offset. (We don't have a DwarfDebug)
1660 // FIXME: we should be able to design DIEEntry reliance on
1663 if (Ref < InputDIE.getOffset()) {
1664 // We must have already cloned that DIE.
1665 uint32_t NewRefOffset =
1666 RefUnit->getStartOffset() + NewRefDie->getOffset();
1667 Attr = new (DIEAlloc) DIEInteger(NewRefOffset);
1669 // A forward reference. Note and fixup later.
1670 Attr = new (DIEAlloc) DIEInteger(0xBADDEF);
1671 Unit.noteForwardReference(NewRefDie, RefUnit, Attr);
1673 Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::DW_FORM_ref_addr,
1678 Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::Form(AttrSpec.Form),
1679 new (DIEAlloc) DIEEntry(*NewRefDie));
1683 /// \brief Clone an attribute of block form (locations, constants) and add
1685 /// \returns the size of the new attribute.
1686 unsigned DwarfLinker::cloneBlockAttribute(DIE &Die, AttributeSpec AttrSpec,
1687 const DWARFFormValue &Val,
1688 unsigned AttrSize) {
1691 DIELoc *Loc = nullptr;
1692 DIEBlock *Block = nullptr;
1693 // Just copy the block data over.
1694 if (AttrSpec.Form == dwarf::DW_FORM_exprloc) {
1695 Loc = new (DIEAlloc) DIELoc();
1696 DIELocs.push_back(Loc);
1698 Block = new (DIEAlloc) DIEBlock();
1699 DIEBlocks.push_back(Block);
1701 Attr = Loc ? static_cast<DIE *>(Loc) : static_cast<DIE *>(Block);
1702 Value = Loc ? static_cast<DIEValue *>(Loc) : static_cast<DIEValue *>(Block);
1703 ArrayRef<uint8_t> Bytes = *Val.getAsBlock();
1704 for (auto Byte : Bytes)
1705 Attr->addValue(static_cast<dwarf::Attribute>(0), dwarf::DW_FORM_data1,
1706 new (DIEAlloc) DIEInteger(Byte));
1707 // FIXME: If DIEBlock and DIELoc just reuses the Size field of
1708 // the DIE class, this if could be replaced by
1709 // Attr->setSize(Bytes.size()).
1712 Loc->ComputeSize(&Streamer->getAsmPrinter());
1714 Block->ComputeSize(&Streamer->getAsmPrinter());
1716 Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::Form(AttrSpec.Form),
1721 /// \brief Clone an address attribute and add it to \p Die.
1722 /// \returns the size of the new attribute.
1723 unsigned DwarfLinker::cloneAddressAttribute(DIE &Die, AttributeSpec AttrSpec,
1724 const DWARFFormValue &Val,
1725 const CompileUnit &Unit,
1726 AttributesInfo &Info) {
1727 uint64_t Addr = *Val.getAsAddress(&Unit.getOrigUnit());
1728 if (AttrSpec.Attr == dwarf::DW_AT_low_pc) {
1729 if (Die.getTag() == dwarf::DW_TAG_inlined_subroutine ||
1730 Die.getTag() == dwarf::DW_TAG_lexical_block)
1731 Addr += Info.PCOffset;
1732 else if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
1733 Addr = Unit.getLowPc();
1734 if (Addr == UINT64_MAX)
1737 } else if (AttrSpec.Attr == dwarf::DW_AT_high_pc) {
1738 if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
1739 if (uint64_t HighPc = Unit.getHighPc())
1744 // If we have a high_pc recorded for the input DIE, use
1745 // it. Otherwise (when no relocations where applied) just use the
1746 // one we just decoded.
1747 Addr = (Info.OrigHighPc ? Info.OrigHighPc : Addr) + Info.PCOffset;
1750 Die.addValue(static_cast<dwarf::Attribute>(AttrSpec.Attr),
1751 static_cast<dwarf::Form>(AttrSpec.Form),
1752 new (DIEAlloc) DIEInteger(Addr));
1753 return Unit.getOrigUnit().getAddressByteSize();
1756 /// \brief Clone a scalar attribute and add it to \p Die.
1757 /// \returns the size of the new attribute.
1758 unsigned DwarfLinker::cloneScalarAttribute(
1759 DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit,
1760 AttributeSpec AttrSpec, const DWARFFormValue &Val, unsigned AttrSize,
1761 const AttributesInfo &Info) {
1763 if (AttrSpec.Attr == dwarf::DW_AT_high_pc &&
1764 Die.getTag() == dwarf::DW_TAG_compile_unit) {
1765 if (Unit.getLowPc() == -1ULL)
1767 // Dwarf >= 4 high_pc is an size, not an address.
1768 Value = Unit.getHighPc() - Unit.getLowPc();
1769 } else if (AttrSpec.Form == dwarf::DW_FORM_sec_offset)
1770 Value = *Val.getAsSectionOffset();
1771 else if (AttrSpec.Form == dwarf::DW_FORM_sdata)
1772 Value = *Val.getAsSignedConstant();
1773 else if (auto OptionalValue = Val.getAsUnsignedConstant())
1774 Value = *OptionalValue;
1776 reportWarning("Unsupported scalar attribute form. Dropping attribute.",
1777 &Unit.getOrigUnit(), &InputDIE);
1780 DIEInteger *Attr = new (DIEAlloc) DIEInteger(Value);
1781 if (AttrSpec.Attr == dwarf::DW_AT_ranges)
1782 Unit.noteRangeAttribute(Die, Attr);
1783 // A more generic way to check for location attributes would be
1784 // nice, but it's very unlikely that any other attribute needs a
1786 else if (AttrSpec.Attr == dwarf::DW_AT_location ||
1787 AttrSpec.Attr == dwarf::DW_AT_frame_base)
1788 Unit.noteLocationAttribute(Attr, Info.PCOffset);
1790 Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::Form(AttrSpec.Form),
1795 /// \brief Clone \p InputDIE's attribute described by \p AttrSpec with
1796 /// value \p Val, and add it to \p Die.
1797 /// \returns the size of the cloned attribute.
1798 unsigned DwarfLinker::cloneAttribute(DIE &Die,
1799 const DWARFDebugInfoEntryMinimal &InputDIE,
1801 const DWARFFormValue &Val,
1802 const AttributeSpec AttrSpec,
1803 unsigned AttrSize, AttributesInfo &Info) {
1804 const DWARFUnit &U = Unit.getOrigUnit();
1806 switch (AttrSpec.Form) {
1807 case dwarf::DW_FORM_strp:
1808 case dwarf::DW_FORM_string:
1809 return cloneStringAttribute(Die, AttrSpec, Val, U);
1810 case dwarf::DW_FORM_ref_addr:
1811 case dwarf::DW_FORM_ref1:
1812 case dwarf::DW_FORM_ref2:
1813 case dwarf::DW_FORM_ref4:
1814 case dwarf::DW_FORM_ref8:
1815 return cloneDieReferenceAttribute(Die, InputDIE, AttrSpec, AttrSize, Val,
1817 case dwarf::DW_FORM_block:
1818 case dwarf::DW_FORM_block1:
1819 case dwarf::DW_FORM_block2:
1820 case dwarf::DW_FORM_block4:
1821 case dwarf::DW_FORM_exprloc:
1822 return cloneBlockAttribute(Die, AttrSpec, Val, AttrSize);
1823 case dwarf::DW_FORM_addr:
1824 return cloneAddressAttribute(Die, AttrSpec, Val, Unit, Info);
1825 case dwarf::DW_FORM_data1:
1826 case dwarf::DW_FORM_data2:
1827 case dwarf::DW_FORM_data4:
1828 case dwarf::DW_FORM_data8:
1829 case dwarf::DW_FORM_udata:
1830 case dwarf::DW_FORM_sdata:
1831 case dwarf::DW_FORM_sec_offset:
1832 case dwarf::DW_FORM_flag:
1833 case dwarf::DW_FORM_flag_present:
1834 return cloneScalarAttribute(Die, InputDIE, Unit, AttrSpec, Val, AttrSize,
1837 reportWarning("Unsupported attribute form in cloneAttribute. Dropping.", &U,
1844 /// \brief Apply the valid relocations found by findValidRelocs() to
1845 /// the buffer \p Data, taking into account that Data is at \p BaseOffset
1846 /// in the debug_info section.
1848 /// Like for findValidRelocs(), this function must be called with
1849 /// monotonic \p BaseOffset values.
1851 /// \returns wether any reloc has been applied.
1852 bool DwarfLinker::applyValidRelocs(MutableArrayRef<char> Data,
1853 uint32_t BaseOffset, bool isLittleEndian) {
1854 assert((NextValidReloc == 0 ||
1855 BaseOffset > ValidRelocs[NextValidReloc - 1].Offset) &&
1856 "BaseOffset should only be increasing.");
1857 if (NextValidReloc >= ValidRelocs.size())
1860 // Skip relocs that haven't been applied.
1861 while (NextValidReloc < ValidRelocs.size() &&
1862 ValidRelocs[NextValidReloc].Offset < BaseOffset)
1865 bool Applied = false;
1866 uint64_t EndOffset = BaseOffset + Data.size();
1867 while (NextValidReloc < ValidRelocs.size() &&
1868 ValidRelocs[NextValidReloc].Offset >= BaseOffset &&
1869 ValidRelocs[NextValidReloc].Offset < EndOffset) {
1870 const auto &ValidReloc = ValidRelocs[NextValidReloc++];
1871 assert(ValidReloc.Offset - BaseOffset < Data.size());
1872 assert(ValidReloc.Offset - BaseOffset + ValidReloc.Size <= Data.size());
1874 uint64_t Value = ValidReloc.Mapping->getValue().BinaryAddress;
1875 Value += ValidReloc.Addend;
1876 for (unsigned i = 0; i != ValidReloc.Size; ++i) {
1877 unsigned Index = isLittleEndian ? i : (ValidReloc.Size - i - 1);
1878 Buf[i] = uint8_t(Value >> (Index * 8));
1880 assert(ValidReloc.Size <= sizeof(Buf));
1881 memcpy(&Data[ValidReloc.Offset - BaseOffset], Buf, ValidReloc.Size);
1888 /// \brief Recursively clone \p InputDIE's subtrees that have been
1889 /// selected to appear in the linked output.
1891 /// \param OutOffset is the Offset where the newly created DIE will
1892 /// lie in the linked compile unit.
1894 /// \returns the cloned DIE object or null if nothing was selected.
1895 DIE *DwarfLinker::cloneDIE(const DWARFDebugInfoEntryMinimal &InputDIE,
1896 CompileUnit &Unit, int64_t PCOffset,
1897 uint32_t OutOffset) {
1898 DWARFUnit &U = Unit.getOrigUnit();
1899 unsigned Idx = U.getDIEIndex(&InputDIE);
1900 CompileUnit::DIEInfo &Info = Unit.getInfo(Idx);
1902 // Should the DIE appear in the output?
1903 if (!Unit.getInfo(Idx).Keep)
1906 uint32_t Offset = InputDIE.getOffset();
1907 // The DIE might have been already created by a forward reference
1908 // (see cloneDieReferenceAttribute()).
1909 DIE *Die = Info.Clone;
1911 Die = Info.Clone = new DIE(dwarf::Tag(InputDIE.getTag()));
1912 assert(Die->getTag() == InputDIE.getTag());
1913 Die->setOffset(OutOffset);
1915 // Extract and clone every attribute.
1916 DataExtractor Data = U.getDebugInfoExtractor();
1917 uint32_t NextOffset = U.getDIEAtIndex(Idx + 1)->getOffset();
1918 AttributesInfo AttrInfo;
1920 // We could copy the data only if we need to aply a relocation to
1921 // it. After testing, it seems there is no performance downside to
1922 // doing the copy unconditionally, and it makes the code simpler.
1923 SmallString<40> DIECopy(Data.getData().substr(Offset, NextOffset - Offset));
1924 Data = DataExtractor(DIECopy, Data.isLittleEndian(), Data.getAddressSize());
1925 // Modify the copy with relocated addresses.
1926 if (applyValidRelocs(DIECopy, Offset, Data.isLittleEndian())) {
1927 // If we applied relocations, we store the value of high_pc that was
1928 // potentially stored in the input DIE. If high_pc is an address
1929 // (Dwarf version == 2), then it might have been relocated to a
1930 // totally unrelated value (because the end address in the object
1931 // file might be start address of another function which got moved
1932 // independantly by the linker). The computation of the actual
1933 // high_pc value is done in cloneAddressAttribute().
1934 AttrInfo.OrigHighPc =
1935 InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_high_pc, 0);
1938 // Reset the Offset to 0 as we will be working on the local copy of
1942 const auto *Abbrev = InputDIE.getAbbreviationDeclarationPtr();
1943 Offset += getULEB128Size(Abbrev->getCode());
1945 // We are entering a subprogram. Get and propagate the PCOffset.
1946 if (Die->getTag() == dwarf::DW_TAG_subprogram)
1947 PCOffset = Info.AddrAdjust;
1948 AttrInfo.PCOffset = PCOffset;
1950 for (const auto &AttrSpec : Abbrev->attributes()) {
1951 DWARFFormValue Val(AttrSpec.Form);
1952 uint32_t AttrSize = Offset;
1953 Val.extractValue(Data, &Offset, &U);
1954 AttrSize = Offset - AttrSize;
1957 cloneAttribute(*Die, InputDIE, Unit, Val, AttrSpec, AttrSize, AttrInfo);
1960 DIEAbbrev &NewAbbrev = Die->getAbbrev();
1961 // If a scope DIE is kept, we must have kept at least one child. If
1962 // it's not the case, we'll just be emitting one wasteful end of
1963 // children marker, but things won't break.
1964 if (InputDIE.hasChildren())
1965 NewAbbrev.setChildrenFlag(dwarf::DW_CHILDREN_yes);
1966 // Assign a permanent abbrev number
1967 AssignAbbrev(Die->getAbbrev());
1969 // Add the size of the abbreviation number to the output offset.
1970 OutOffset += getULEB128Size(Die->getAbbrevNumber());
1972 if (!Abbrev->hasChildren()) {
1974 Die->setSize(OutOffset - Die->getOffset());
1978 // Recursively clone children.
1979 for (auto *Child = InputDIE.getFirstChild(); Child && !Child->isNULL();
1980 Child = Child->getSibling()) {
1981 if (DIE *Clone = cloneDIE(*Child, Unit, PCOffset, OutOffset)) {
1982 Die->addChild(std::unique_ptr<DIE>(Clone));
1983 OutOffset = Clone->getOffset() + Clone->getSize();
1987 // Account for the end of children marker.
1988 OutOffset += sizeof(int8_t);
1990 Die->setSize(OutOffset - Die->getOffset());
1994 /// \brief Patch the input object file relevant debug_ranges entries
1995 /// and emit them in the output file. Update the relevant attributes
1996 /// to point at the new entries.
1997 void DwarfLinker::patchRangesForUnit(const CompileUnit &Unit,
1998 DWARFContext &OrigDwarf) const {
1999 DWARFDebugRangeList RangeList;
2000 const auto &FunctionRanges = Unit.getFunctionRanges();
2001 unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
2002 DataExtractor RangeExtractor(OrigDwarf.getRangeSection(),
2003 OrigDwarf.isLittleEndian(), AddressSize);
2004 auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
2005 DWARFUnit &OrigUnit = Unit.getOrigUnit();
2006 const auto *OrigUnitDie = OrigUnit.getCompileUnitDIE(false);
2007 uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress(
2008 &OrigUnit, dwarf::DW_AT_low_pc, -1ULL);
2009 // Ranges addresses are based on the unit's low_pc. Compute the
2010 // offset we need to apply to adapt to the the new unit's low_pc.
2011 int64_t UnitPcOffset = 0;
2012 if (OrigLowPc != -1ULL)
2013 UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc();
2015 for (const auto &RangeAttribute : Unit.getRangesAttributes()) {
2016 uint32_t Offset = RangeAttribute->getValue();
2017 RangeAttribute->setValue(Streamer->getRangesSectionSize());
2018 RangeList.extract(RangeExtractor, &Offset);
2019 const auto &Entries = RangeList.getEntries();
2020 const DWARFDebugRangeList::RangeListEntry &First = Entries.front();
2022 if (CurrRange == InvalidRange || First.StartAddress < CurrRange.start() ||
2023 First.StartAddress >= CurrRange.stop()) {
2024 CurrRange = FunctionRanges.find(First.StartAddress + OrigLowPc);
2025 if (CurrRange == InvalidRange ||
2026 CurrRange.start() > First.StartAddress + OrigLowPc) {
2027 reportWarning("no mapping for range.");
2032 Streamer->emitRangesEntries(UnitPcOffset, OrigLowPc, CurrRange, Entries,
2037 /// \brief Generate the debug_aranges entries for \p Unit and if the
2038 /// unit has a DW_AT_ranges attribute, also emit the debug_ranges
2039 /// contribution for this attribute.
2040 /// FIXME: this could actually be done right in patchRangesForUnit,
2041 /// but for the sake of initial bit-for-bit compatibility with legacy
2042 /// dsymutil, we have to do it in a delayed pass.
2043 void DwarfLinker::generateUnitRanges(CompileUnit &Unit) const {
2044 DIEInteger *Attr = Unit.getUnitRangesAttribute();
2046 Attr->setValue(Streamer->getRangesSectionSize());
2047 Streamer->emitUnitRangesEntries(Unit, Attr != nullptr);
2050 /// \brief Insert the new line info sequence \p Seq into the current
2051 /// set of already linked line info \p Rows.
2052 static void insertLineSequence(std::vector<DWARFDebugLine::Row> &Seq,
2053 std::vector<DWARFDebugLine::Row> &Rows) {
2057 if (!Rows.empty() && Rows.back().Address < Seq.front().Address) {
2058 Rows.insert(Rows.end(), Seq.begin(), Seq.end());
2063 auto InsertPoint = std::lower_bound(
2064 Rows.begin(), Rows.end(), Seq.front(),
2065 [](const DWARFDebugLine::Row &LHS, const DWARFDebugLine::Row &RHS) {
2066 return LHS.Address < RHS.Address;
2069 // FIXME: this only removes the unneeded end_sequence if the
2070 // sequences have been inserted in order. using a global sort like
2071 // described in patchLineTableForUnit() and delaying the end_sequene
2072 // elimination to emitLineTableForUnit() we can get rid of all of them.
2073 if (InsertPoint != Rows.end() &&
2074 InsertPoint->Address == Seq.front().Address && InsertPoint->EndSequence) {
2075 *InsertPoint = Seq.front();
2076 Rows.insert(InsertPoint + 1, Seq.begin() + 1, Seq.end());
2078 Rows.insert(InsertPoint, Seq.begin(), Seq.end());
2084 /// \brief Extract the line table for \p Unit from \p OrigDwarf, and
2085 /// recreate a relocated version of these for the address ranges that
2086 /// are present in the binary.
2087 void DwarfLinker::patchLineTableForUnit(CompileUnit &Unit,
2088 DWARFContext &OrigDwarf) {
2089 const DWARFDebugInfoEntryMinimal *CUDie =
2090 Unit.getOrigUnit().getCompileUnitDIE();
2091 uint64_t StmtList = CUDie->getAttributeValueAsSectionOffset(
2092 &Unit.getOrigUnit(), dwarf::DW_AT_stmt_list, -1ULL);
2093 if (StmtList == -1ULL)
2096 // Update the cloned DW_AT_stmt_list with the correct debug_line offset.
2097 if (auto *OutputDIE = Unit.getOutputUnitDIE()) {
2098 const auto &Abbrev = OutputDIE->getAbbrev().getData();
2099 auto Stmt = std::find_if(
2100 Abbrev.begin(), Abbrev.end(), [](const DIEAbbrevData &AbbrevData) {
2101 return AbbrevData.getAttribute() == dwarf::DW_AT_stmt_list;
2103 assert(Stmt < Abbrev.end() && "Didn't find DW_AT_stmt_list in cloned DIE!");
2104 DIEInteger *StmtAttr =
2105 cast<DIEInteger>(OutputDIE->getValues()[Stmt - Abbrev.begin()]);
2106 StmtAttr->setValue(Streamer->getLineSectionSize());
2109 // Parse the original line info for the unit.
2110 DWARFDebugLine::LineTable LineTable;
2111 uint32_t StmtOffset = StmtList;
2112 StringRef LineData = OrigDwarf.getLineSection().Data;
2113 DataExtractor LineExtractor(LineData, OrigDwarf.isLittleEndian(),
2114 Unit.getOrigUnit().getAddressByteSize());
2115 LineTable.parse(LineExtractor, &OrigDwarf.getLineSection().Relocs,
2118 // This vector is the output line table.
2119 std::vector<DWARFDebugLine::Row> NewRows;
2120 NewRows.reserve(LineTable.Rows.size());
2122 // Current sequence of rows being extracted, before being inserted
2124 std::vector<DWARFDebugLine::Row> Seq;
2125 const auto &FunctionRanges = Unit.getFunctionRanges();
2126 auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
2128 // FIXME: This logic is meant to generate exactly the same output as
2129 // Darwin's classic dsynutil. There is a nicer way to implement this
2130 // by simply putting all the relocated line info in NewRows and simply
2131 // sorting NewRows before passing it to emitLineTableForUnit. This
2132 // should be correct as sequences for a function should stay
2133 // together in the sorted output. There are a few corner cases that
2134 // look suspicious though, and that required to implement the logic
2135 // this way. Revisit that once initial validation is finished.
2137 // Iterate over the object file line info and extract the sequences
2138 // that correspond to linked functions.
2139 for (auto &Row : LineTable.Rows) {
2140 // Check wether we stepped out of the range. The range is
2141 // half-open, but consider accept the end address of the range if
2142 // it is marked as end_sequence in the input (because in that
2143 // case, the relocation offset is accurate and that entry won't
2144 // serve as the start of another function).
2145 if (CurrRange == InvalidRange || Row.Address < CurrRange.start() ||
2146 Row.Address > CurrRange.stop() ||
2147 (Row.Address == CurrRange.stop() && !Row.EndSequence)) {
2148 // We just stepped out of a known range. Insert a end_sequence
2149 // corresponding to the end of the range.
2150 uint64_t StopAddress = CurrRange != InvalidRange
2151 ? CurrRange.stop() + CurrRange.value()
2153 CurrRange = FunctionRanges.find(Row.Address);
2154 bool CurrRangeValid =
2155 CurrRange != InvalidRange && CurrRange.start() <= Row.Address;
2156 if (!CurrRangeValid) {
2157 CurrRange = InvalidRange;
2158 if (StopAddress != -1ULL) {
2159 // Try harder by looking in the DebugMapObject function
2160 // ranges map. There are corner cases where this finds a
2161 // valid entry. It's unclear if this is right or wrong, but
2162 // for now do as dsymutil.
2163 // FIXME: Understand exactly what cases this addresses and
2164 // potentially remove it along with the Ranges map.
2165 auto Range = Ranges.lower_bound(Row.Address);
2166 if (Range != Ranges.begin() && Range != Ranges.end())
2169 if (Range != Ranges.end() && Range->first <= Row.Address &&
2170 Range->second.first >= Row.Address) {
2171 StopAddress = Row.Address + Range->second.second;
2175 if (StopAddress != -1ULL && !Seq.empty()) {
2176 // Insert end sequence row with the computed end address, but
2177 // the same line as the previous one.
2178 Seq.emplace_back(Seq.back());
2179 Seq.back().Address = StopAddress;
2180 Seq.back().EndSequence = 1;
2181 Seq.back().PrologueEnd = 0;
2182 Seq.back().BasicBlock = 0;
2183 Seq.back().EpilogueBegin = 0;
2184 insertLineSequence(Seq, NewRows);
2187 if (!CurrRangeValid)
2191 // Ignore empty sequences.
2192 if (Row.EndSequence && Seq.empty())
2195 // Relocate row address and add it to the current sequence.
2196 Row.Address += CurrRange.value();
2197 Seq.emplace_back(Row);
2199 if (Row.EndSequence)
2200 insertLineSequence(Seq, NewRows);
2203 // Finished extracting, now emit the line tables.
2204 uint32_t PrologueEnd = StmtList + 10 + LineTable.Prologue.PrologueLength;
2205 // FIXME: LLVM hardcodes it's prologue values. We just copy the
2206 // prologue over and that works because we act as both producer and
2207 // consumer. It would be nicer to have a real configurable line
2209 if (LineTable.Prologue.Version != 2 ||
2210 LineTable.Prologue.DefaultIsStmt != DWARF2_LINE_DEFAULT_IS_STMT ||
2211 LineTable.Prologue.LineBase != -5 || LineTable.Prologue.LineRange != 14 ||
2212 LineTable.Prologue.OpcodeBase != 13)
2213 reportWarning("line table paramters mismatch. Cannot emit.");
2215 Streamer->emitLineTableForUnit(LineData.slice(StmtList + 4, PrologueEnd),
2216 LineTable.Prologue.MinInstLength, NewRows,
2217 Unit.getOrigUnit().getAddressByteSize());
2220 bool DwarfLinker::link(const DebugMap &Map) {
2222 if (Map.begin() == Map.end()) {
2223 errs() << "Empty debug map.\n";
2227 if (!createStreamer(Map.getTriple(), OutputFilename))
2230 // Size of the DIEs (and headers) generated for the linked output.
2231 uint64_t OutputDebugInfoSize = 0;
2232 // A unique ID that identifies each compile unit.
2233 unsigned UnitID = 0;
2234 for (const auto &Obj : Map.objects()) {
2235 CurrentDebugObject = Obj.get();
2237 if (Options.Verbose)
2238 outs() << "DEBUG MAP OBJECT: " << Obj->getObjectFilename() << "\n";
2239 auto ErrOrObj = BinHolder.GetObjectFile(Obj->getObjectFilename());
2240 if (std::error_code EC = ErrOrObj.getError()) {
2241 reportWarning(Twine(Obj->getObjectFilename()) + ": " + EC.message());
2245 // Look for relocations that correspond to debug map entries.
2246 if (!findValidRelocsInDebugInfo(*ErrOrObj, *Obj)) {
2247 if (Options.Verbose)
2248 outs() << "No valid relocations found. Skipping.\n";
2252 // Setup access to the debug info.
2253 DWARFContextInMemory DwarfContext(*ErrOrObj);
2254 startDebugObject(DwarfContext, *Obj);
2256 // In a first phase, just read in the debug info and store the DIE
2257 // parent links that we will use during the next phase.
2258 for (const auto &CU : DwarfContext.compile_units()) {
2259 auto *CUDie = CU->getCompileUnitDIE(false);
2260 if (Options.Verbose) {
2261 outs() << "Input compilation unit:";
2262 CUDie->dump(outs(), CU.get(), 0);
2264 Units.emplace_back(*CU, UnitID++);
2265 gatherDIEParents(CUDie, 0, Units.back());
2268 // Then mark all the DIEs that need to be present in the linked
2269 // output and collect some information about them. Note that this
2270 // loop can not be merged with the previous one becaue cross-cu
2271 // references require the ParentIdx to be setup for every CU in
2272 // the object file before calling this.
2273 for (auto &CurrentUnit : Units)
2274 lookForDIEsToKeep(*CurrentUnit.getOrigUnit().getCompileUnitDIE(), *Obj,
2277 // The calls to applyValidRelocs inside cloneDIE will walk the
2278 // reloc array again (in the same way findValidRelocsInDebugInfo()
2279 // did). We need to reset the NextValidReloc index to the beginning.
2282 // Construct the output DIE tree by cloning the DIEs we chose to
2283 // keep above. If there are no valid relocs, then there's nothing
2285 if (!ValidRelocs.empty())
2286 for (auto &CurrentUnit : Units) {
2287 const auto *InputDIE = CurrentUnit.getOrigUnit().getCompileUnitDIE();
2288 CurrentUnit.setStartOffset(OutputDebugInfoSize);
2289 DIE *OutputDIE = cloneDIE(*InputDIE, CurrentUnit, 0 /* PCOffset */,
2290 11 /* Unit Header size */);
2291 CurrentUnit.setOutputUnitDIE(OutputDIE);
2292 OutputDebugInfoSize = CurrentUnit.computeNextUnitOffset();
2293 if (Options.NoOutput)
2295 // FIXME: for compatibility with the classic dsymutil, we emit
2296 // an empty line table for the unit, even if the unit doesn't
2297 // actually exist in the DIE tree.
2298 patchLineTableForUnit(CurrentUnit, DwarfContext);
2301 patchRangesForUnit(CurrentUnit, DwarfContext);
2302 Streamer->emitLocationsForUnit(CurrentUnit, DwarfContext);
2305 // Emit all the compile unit's debug information.
2306 if (!ValidRelocs.empty() && !Options.NoOutput)
2307 for (auto &CurrentUnit : Units) {
2308 generateUnitRanges(CurrentUnit);
2309 CurrentUnit.fixupForwardReferences();
2310 Streamer->emitCompileUnitHeader(CurrentUnit);
2311 if (!CurrentUnit.getOutputUnitDIE())
2313 Streamer->emitDIE(*CurrentUnit.getOutputUnitDIE());
2316 // Clean-up before starting working on the next object.
2320 // Emit everything that's global.
2321 if (!Options.NoOutput) {
2322 Streamer->emitAbbrevs(Abbreviations);
2323 Streamer->emitStrings(StringPool);
2326 return Options.NoOutput ? true : Streamer->finish();
2330 bool linkDwarf(StringRef OutputFilename, const DebugMap &DM,
2331 const LinkOptions &Options) {
2332 DwarfLinker Linker(OutputFilename, Options);
2333 return Linker.link(DM);