1 //===- DWARFDie.cpp -------------------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
11 #include "llvm/ADT/None.h"
12 #include "llvm/ADT/Optional.h"
13 #include "llvm/ADT/SmallSet.h"
14 #include "llvm/ADT/StringRef.h"
15 #include "llvm/BinaryFormat/Dwarf.h"
16 #include "llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h"
17 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
18 #include "llvm/DebugInfo/DWARF/DWARFDebugRangeList.h"
19 #include "llvm/DebugInfo/DWARF/DWARFExpression.h"
20 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
21 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
22 #include "llvm/Object/ObjectFile.h"
23 #include "llvm/Support/DataExtractor.h"
24 #include "llvm/Support/Format.h"
25 #include "llvm/Support/FormatVariadic.h"
26 #include "llvm/Support/MathExtras.h"
27 #include "llvm/Support/WithColor.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include <algorithm>
30 #include <cassert>
31 #include <cinttypes>
32 #include <cstdint>
33 #include <string>
34 #include <utility>
35 
36 using namespace llvm;
37 using namespace dwarf;
38 using namespace object;
39 
40 static void dumpApplePropertyAttribute(raw_ostream &OS, uint64_t Val) {
41   OS << " (";
42   do {
43     uint64_t Shift = countTrailingZeros(Val);
44     assert(Shift < 64 && "undefined behavior");
45     uint64_t Bit = 1ULL << Shift;
46     auto PropName = ApplePropertyString(Bit);
47     if (!PropName.empty())
48       OS << PropName;
49     else
50       OS << format("DW_APPLE_PROPERTY_0x%" PRIx64, Bit);
51     if (!(Val ^= Bit))
52       break;
53     OS << ", ";
54   } while (true);
55   OS << ")";
56 }
57 
58 static void dumpRanges(const DWARFObject &Obj, raw_ostream &OS,
59                        const DWARFAddressRangesVector &Ranges,
60                        unsigned AddressSize, unsigned Indent,
61                        const DIDumpOptions &DumpOpts) {
62   ArrayRef<SectionName> SectionNames;
63   if (DumpOpts.Verbose)
64     SectionNames = Obj.getSectionNames();
65 
66   for (const DWARFAddressRange &R : Ranges) {
67 
68     OS << '\n';
69     OS.indent(Indent);
70     R.dump(OS, AddressSize);
71 
72     if (SectionNames.empty() || R.SectionIndex == -1ULL)
73       continue;
74 
75     StringRef Name = SectionNames[R.SectionIndex].Name;
76     OS << " \"" << Name << '\"';
77 
78     // Print section index if name is not unique.
79     if (!SectionNames[R.SectionIndex].IsNameUnique)
80       OS << format(" [%" PRIu64 "]", R.SectionIndex);
81   }
82 }
83 
84 static void dumpLocation(raw_ostream &OS, DWARFFormValue &FormValue,
85                          DWARFUnit *U, unsigned Indent,
86                          DIDumpOptions DumpOpts) {
87   DWARFContext &Ctx = U->getContext();
88   const DWARFObject &Obj = Ctx.getDWARFObj();
89   const MCRegisterInfo *MRI = Ctx.getRegisterInfo();
90   if (FormValue.isFormClass(DWARFFormValue::FC_Block) ||
91       FormValue.isFormClass(DWARFFormValue::FC_Exprloc)) {
92     ArrayRef<uint8_t> Expr = *FormValue.getAsBlock();
93     DataExtractor Data(StringRef((const char *)Expr.data(), Expr.size()),
94                        Ctx.isLittleEndian(), 0);
95     DWARFExpression(Data, U->getVersion(), U->getAddressByteSize())
96         .print(OS, MRI);
97     return;
98   }
99 
100   FormValue.dump(OS, DumpOpts);
101   if (FormValue.isFormClass(DWARFFormValue::FC_SectionOffset)) {
102     const DWARFSection &LocSection = Obj.getLocSection();
103     const DWARFSection &LocDWOSection = Obj.getLocDWOSection();
104     uint32_t Offset = *FormValue.getAsSectionOffset();
105     if (!LocSection.Data.empty()) {
106       DWARFDebugLoc DebugLoc;
107       DWARFDataExtractor Data(Obj, LocSection, Ctx.isLittleEndian(),
108                               Obj.getAddressSize());
109       auto LL = DebugLoc.parseOneLocationList(Data, &Offset);
110       if (LL) {
111         uint64_t BaseAddr = 0;
112         if (Optional<BaseAddress> BA = U->getBaseAddress())
113           BaseAddr = BA->Address;
114         LL->dump(OS, Ctx.isLittleEndian(), Obj.getAddressSize(), MRI, BaseAddr,
115                  Indent);
116       } else
117         OS << "error extracting location list.";
118     } else if (!LocDWOSection.Data.empty()) {
119       DataExtractor Data(LocDWOSection.Data, Ctx.isLittleEndian(), 0);
120       auto LL = DWARFDebugLocDWO::parseOneLocationList(Data, &Offset);
121       if (LL)
122         LL->dump(OS, Ctx.isLittleEndian(), Obj.getAddressSize(), MRI, Indent);
123       else
124         OS << "error extracting location list.";
125     }
126   }
127 }
128 
129 /// Dump the name encoded in the type tag.
130 static void dumpTypeTagName(raw_ostream &OS, dwarf::Tag T) {
131   StringRef TagStr = TagString(T);
132   if (!TagStr.startswith("DW_TAG_") || !TagStr.endswith("_type"))
133     return;
134   OS << TagStr.substr(7, TagStr.size() - 12) << " ";
135 }
136 
137 /// Recursively dump the DIE type name when applicable.
138 static void dumpTypeName(raw_ostream &OS, const DWARFDie &Die) {
139   DWARFDie D = Die.getAttributeValueAsReferencedDie(DW_AT_type);
140 
141   if (!D.isValid())
142     return;
143 
144   if (const char *Name = D.getName(DINameKind::LinkageName)) {
145     OS << Name;
146     return;
147   }
148 
149   // FIXME: We should have pretty printers per language. Currently we print
150   // everything as if it was C++ and fall back to the TAG type name.
151   const dwarf::Tag T = D.getTag();
152   switch (T) {
153   case DW_TAG_array_type:
154   case DW_TAG_pointer_type:
155   case DW_TAG_ptr_to_member_type:
156   case DW_TAG_reference_type:
157   case DW_TAG_rvalue_reference_type:
158     break;
159   default:
160     dumpTypeTagName(OS, T);
161   }
162 
163   // Follow the DW_AT_type if possible.
164   dumpTypeName(OS, D);
165 
166   switch (T) {
167   case DW_TAG_array_type:
168     OS << "[]";
169     break;
170   case DW_TAG_pointer_type:
171     OS << '*';
172     break;
173   case DW_TAG_ptr_to_member_type:
174     OS << '*';
175     break;
176   case DW_TAG_reference_type:
177     OS << '&';
178     break;
179   case DW_TAG_rvalue_reference_type:
180     OS << "&&";
181     break;
182   default:
183     break;
184   }
185 }
186 
187 static void dumpAttribute(raw_ostream &OS, const DWARFDie &Die,
188                           uint32_t *OffsetPtr, dwarf::Attribute Attr,
189                           dwarf::Form Form, unsigned Indent,
190                           DIDumpOptions DumpOpts) {
191   if (!Die.isValid())
192     return;
193   const char BaseIndent[] = "            ";
194   OS << BaseIndent;
195   OS.indent(Indent + 2);
196   WithColor(OS, HighlightColor::Attribute) << formatv("{0}", Attr);
197 
198   if (DumpOpts.Verbose || DumpOpts.ShowForm)
199     OS << formatv(" [{0}]", Form);
200 
201   DWARFUnit *U = Die.getDwarfUnit();
202   DWARFFormValue formValue(Form);
203 
204   if (!formValue.extractValue(U->getDebugInfoExtractor(), OffsetPtr,
205                               U->getFormParams(), U))
206     return;
207 
208   OS << "\t(";
209 
210   StringRef Name;
211   std::string File;
212   auto Color = HighlightColor::Enumerator;
213   if (Attr == DW_AT_decl_file || Attr == DW_AT_call_file) {
214     Color = HighlightColor::String;
215     if (const auto *LT = U->getContext().getLineTableForUnit(U))
216       if (LT->getFileNameByIndex(
217               formValue.getAsUnsignedConstant().getValue(),
218               U->getCompilationDir(),
219               DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, File)) {
220         File = '"' + File + '"';
221         Name = File;
222       }
223   } else if (Optional<uint64_t> Val = formValue.getAsUnsignedConstant())
224     Name = AttributeValueString(Attr, *Val);
225 
226   if (!Name.empty())
227     WithColor(OS, Color) << Name;
228   else if (Attr == DW_AT_decl_line || Attr == DW_AT_call_line)
229     OS << *formValue.getAsUnsignedConstant();
230   else if (Attr == DW_AT_high_pc && !DumpOpts.ShowForm && !DumpOpts.Verbose &&
231            formValue.getAsUnsignedConstant()) {
232     if (DumpOpts.ShowAddresses) {
233       // Print the actual address rather than the offset.
234       uint64_t LowPC, HighPC, Index;
235       if (Die.getLowAndHighPC(LowPC, HighPC, Index))
236         OS << format("0x%016" PRIx64, HighPC);
237       else
238         formValue.dump(OS, DumpOpts);
239     }
240   } else if (Attr == DW_AT_location || Attr == DW_AT_frame_base ||
241              Attr == DW_AT_data_member_location ||
242              Attr == DW_AT_GNU_call_site_value)
243     dumpLocation(OS, formValue, U, sizeof(BaseIndent) + Indent + 4, DumpOpts);
244   else
245     formValue.dump(OS, DumpOpts);
246 
247   // We have dumped the attribute raw value. For some attributes
248   // having both the raw value and the pretty-printed value is
249   // interesting. These attributes are handled below.
250   if (Attr == DW_AT_specification || Attr == DW_AT_abstract_origin) {
251     if (const char *Name = Die.getAttributeValueAsReferencedDie(Attr).getName(
252             DINameKind::LinkageName))
253       OS << " \"" << Name << '\"';
254   } else if (Attr == DW_AT_type) {
255     OS << " \"";
256     dumpTypeName(OS, Die);
257     OS << '"';
258   } else if (Attr == DW_AT_APPLE_property_attribute) {
259     if (Optional<uint64_t> OptVal = formValue.getAsUnsignedConstant())
260       dumpApplePropertyAttribute(OS, *OptVal);
261   } else if (Attr == DW_AT_ranges) {
262     const DWARFObject &Obj = Die.getDwarfUnit()->getContext().getDWARFObj();
263     // For DW_FORM_rnglistx we need to dump the offset separately, since
264     // we have only dumped the index so far.
265     Optional<DWARFFormValue> Value = Die.find(DW_AT_ranges);
266     if (Value && Value->getForm() == DW_FORM_rnglistx)
267       if (auto RangeListOffset =
268               U->getRnglistOffset(*Value->getAsSectionOffset())) {
269         DWARFFormValue FV(dwarf::DW_FORM_sec_offset);
270         FV.setUValue(*RangeListOffset);
271         FV.dump(OS, DumpOpts);
272       }
273     if (auto RangesOrError = Die.getAddressRanges())
274       dumpRanges(Obj, OS, RangesOrError.get(), U->getAddressByteSize(),
275                  sizeof(BaseIndent) + Indent + 4, DumpOpts);
276     else
277       WithColor::error() << "decoding address ranges: "
278                          << toString(RangesOrError.takeError()) << '\n';
279   }
280 
281   OS << ")\n";
282 }
283 
284 bool DWARFDie::isSubprogramDIE() const { return getTag() == DW_TAG_subprogram; }
285 
286 bool DWARFDie::isSubroutineDIE() const {
287   auto Tag = getTag();
288   return Tag == DW_TAG_subprogram || Tag == DW_TAG_inlined_subroutine;
289 }
290 
291 Optional<DWARFFormValue> DWARFDie::find(dwarf::Attribute Attr) const {
292   if (!isValid())
293     return None;
294   auto AbbrevDecl = getAbbreviationDeclarationPtr();
295   if (AbbrevDecl)
296     return AbbrevDecl->getAttributeValue(getOffset(), Attr, *U);
297   return None;
298 }
299 
300 Optional<DWARFFormValue>
301 DWARFDie::find(ArrayRef<dwarf::Attribute> Attrs) const {
302   if (!isValid())
303     return None;
304   auto AbbrevDecl = getAbbreviationDeclarationPtr();
305   if (AbbrevDecl) {
306     for (auto Attr : Attrs) {
307       if (auto Value = AbbrevDecl->getAttributeValue(getOffset(), Attr, *U))
308         return Value;
309     }
310   }
311   return None;
312 }
313 
314 Optional<DWARFFormValue>
315 DWARFDie::findRecursively(ArrayRef<dwarf::Attribute> Attrs) const {
316   std::vector<DWARFDie> Worklist;
317   Worklist.push_back(*this);
318 
319   // Keep track if DIEs already seen to prevent infinite recursion.
320   // Empirically we rarely see a depth of more than 3 when dealing with valid
321   // DWARF. This corresponds to following the DW_AT_abstract_origin and
322   // DW_AT_specification just once.
323   SmallSet<DWARFDie, 3> Seen;
324 
325   while (!Worklist.empty()) {
326     DWARFDie Die = Worklist.back();
327     Worklist.pop_back();
328 
329     if (!Die.isValid())
330       continue;
331 
332     if (Seen.count(Die))
333       continue;
334 
335     Seen.insert(Die);
336 
337     if (auto Value = Die.find(Attrs))
338       return Value;
339 
340     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_abstract_origin))
341       Worklist.push_back(D);
342 
343     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_specification))
344       Worklist.push_back(D);
345   }
346 
347   return None;
348 }
349 
350 DWARFDie
351 DWARFDie::getAttributeValueAsReferencedDie(dwarf::Attribute Attr) const {
352   if (auto SpecRef = toReference(find(Attr))) {
353     if (auto SpecUnit = U->getUnitSection().getUnitForOffset(*SpecRef))
354       return SpecUnit->getDIEForOffset(*SpecRef);
355   }
356   return DWARFDie();
357 }
358 
359 Optional<uint64_t> DWARFDie::getRangesBaseAttribute() const {
360   return toSectionOffset(find({DW_AT_rnglists_base, DW_AT_GNU_ranges_base}));
361 }
362 
363 Optional<uint64_t> DWARFDie::getHighPC(uint64_t LowPC) const {
364   if (auto FormValue = find(DW_AT_high_pc)) {
365     if (auto Address = FormValue->getAsAddress()) {
366       // High PC is an address.
367       return Address;
368     }
369     if (auto Offset = FormValue->getAsUnsignedConstant()) {
370       // High PC is an offset from LowPC.
371       return LowPC + *Offset;
372     }
373   }
374   return None;
375 }
376 
377 bool DWARFDie::getLowAndHighPC(uint64_t &LowPC, uint64_t &HighPC,
378                                uint64_t &SectionIndex) const {
379   auto F = find(DW_AT_low_pc);
380   auto LowPcAddr = toAddress(F);
381   if (!LowPcAddr)
382     return false;
383   if (auto HighPcAddr = getHighPC(*LowPcAddr)) {
384     LowPC = *LowPcAddr;
385     HighPC = *HighPcAddr;
386     SectionIndex = F->getSectionIndex();
387     return true;
388   }
389   return false;
390 }
391 
392 Expected<DWARFAddressRangesVector> DWARFDie::getAddressRanges() const {
393   if (isNULL())
394     return DWARFAddressRangesVector();
395   // Single range specified by low/high PC.
396   uint64_t LowPC, HighPC, Index;
397   if (getLowAndHighPC(LowPC, HighPC, Index))
398     return DWARFAddressRangesVector{{LowPC, HighPC, Index}};
399 
400   Optional<DWARFFormValue> Value = find(DW_AT_ranges);
401   if (Value) {
402     if (Value->getForm() == DW_FORM_rnglistx)
403       return U->findRnglistFromIndex(*Value->getAsSectionOffset());
404     return U->findRnglistFromOffset(*Value->getAsSectionOffset());
405   }
406   return DWARFAddressRangesVector();
407 }
408 
409 void DWARFDie::collectChildrenAddressRanges(
410     DWARFAddressRangesVector &Ranges) const {
411   if (isNULL())
412     return;
413   if (isSubprogramDIE()) {
414     if (auto DIERangesOrError = getAddressRanges())
415       Ranges.insert(Ranges.end(), DIERangesOrError.get().begin(),
416                     DIERangesOrError.get().end());
417     else
418       llvm::consumeError(DIERangesOrError.takeError());
419   }
420 
421   for (auto Child : children())
422     Child.collectChildrenAddressRanges(Ranges);
423 }
424 
425 bool DWARFDie::addressRangeContainsAddress(const uint64_t Address) const {
426   auto RangesOrError = getAddressRanges();
427   if (!RangesOrError) {
428     llvm::consumeError(RangesOrError.takeError());
429     return false;
430   }
431 
432   for (const auto &R : RangesOrError.get())
433     if (R.LowPC <= Address && Address < R.HighPC)
434       return true;
435   return false;
436 }
437 
438 const char *DWARFDie::getSubroutineName(DINameKind Kind) const {
439   if (!isSubroutineDIE())
440     return nullptr;
441   return getName(Kind);
442 }
443 
444 const char *DWARFDie::getName(DINameKind Kind) const {
445   if (!isValid() || Kind == DINameKind::None)
446     return nullptr;
447   // Try to get mangled name only if it was asked for.
448   if (Kind == DINameKind::LinkageName) {
449     if (auto Name = dwarf::toString(
450             findRecursively({DW_AT_MIPS_linkage_name, DW_AT_linkage_name}),
451             nullptr))
452       return Name;
453   }
454   if (auto Name = dwarf::toString(findRecursively(DW_AT_name), nullptr))
455     return Name;
456   return nullptr;
457 }
458 
459 uint64_t DWARFDie::getDeclLine() const {
460   return toUnsigned(findRecursively(DW_AT_decl_line), 0);
461 }
462 
463 void DWARFDie::getCallerFrame(uint32_t &CallFile, uint32_t &CallLine,
464                               uint32_t &CallColumn,
465                               uint32_t &CallDiscriminator) const {
466   CallFile = toUnsigned(find(DW_AT_call_file), 0);
467   CallLine = toUnsigned(find(DW_AT_call_line), 0);
468   CallColumn = toUnsigned(find(DW_AT_call_column), 0);
469   CallDiscriminator = toUnsigned(find(DW_AT_GNU_discriminator), 0);
470 }
471 
472 /// Helper to dump a DIE with all of its parents, but no siblings.
473 static unsigned dumpParentChain(DWARFDie Die, raw_ostream &OS, unsigned Indent,
474                                 DIDumpOptions DumpOpts) {
475   if (!Die)
476     return Indent;
477   Indent = dumpParentChain(Die.getParent(), OS, Indent, DumpOpts);
478   Die.dump(OS, Indent, DumpOpts);
479   return Indent + 2;
480 }
481 
482 void DWARFDie::dump(raw_ostream &OS, unsigned Indent,
483                     DIDumpOptions DumpOpts) const {
484   if (!isValid())
485     return;
486   DWARFDataExtractor debug_info_data = U->getDebugInfoExtractor();
487   const uint32_t Offset = getOffset();
488   uint32_t offset = Offset;
489   if (DumpOpts.ShowParents) {
490     DIDumpOptions ParentDumpOpts = DumpOpts;
491     ParentDumpOpts.ShowParents = false;
492     ParentDumpOpts.ShowChildren = false;
493     Indent = dumpParentChain(getParent(), OS, Indent, ParentDumpOpts);
494   }
495 
496   if (debug_info_data.isValidOffset(offset)) {
497     uint32_t abbrCode = debug_info_data.getULEB128(&offset);
498     if (DumpOpts.ShowAddresses)
499       WithColor(OS, HighlightColor::Address).get()
500           << format("\n0x%8.8x: ", Offset);
501 
502     if (abbrCode) {
503       auto AbbrevDecl = getAbbreviationDeclarationPtr();
504       if (AbbrevDecl) {
505         WithColor(OS, HighlightColor::Tag).get().indent(Indent)
506             << formatv("{0}", getTag());
507         if (DumpOpts.Verbose)
508           OS << format(" [%u] %c", abbrCode,
509                        AbbrevDecl->hasChildren() ? '*' : ' ');
510         OS << '\n';
511 
512         // Dump all data in the DIE for the attributes.
513         for (const auto &AttrSpec : AbbrevDecl->attributes()) {
514           if (AttrSpec.Form == DW_FORM_implicit_const) {
515             // We are dumping .debug_info section ,
516             // implicit_const attribute values are not really stored here,
517             // but in .debug_abbrev section. So we just skip such attrs.
518             continue;
519           }
520           dumpAttribute(OS, *this, &offset, AttrSpec.Attr, AttrSpec.Form,
521                         Indent, DumpOpts);
522         }
523 
524         DWARFDie child = getFirstChild();
525         if (DumpOpts.ShowChildren && DumpOpts.RecurseDepth > 0 && child) {
526           DumpOpts.RecurseDepth--;
527           DIDumpOptions ChildDumpOpts = DumpOpts;
528           ChildDumpOpts.ShowParents = false;
529           while (child) {
530             child.dump(OS, Indent + 2, ChildDumpOpts);
531             child = child.getSibling();
532           }
533         }
534       } else {
535         OS << "Abbreviation code not found in 'debug_abbrev' class for code: "
536            << abbrCode << '\n';
537       }
538     } else {
539       OS.indent(Indent) << "NULL\n";
540     }
541   }
542 }
543 
544 LLVM_DUMP_METHOD void DWARFDie::dump() const { dump(llvm::errs(), 0); }
545 
546 DWARFDie DWARFDie::getParent() const {
547   if (isValid())
548     return U->getParent(Die);
549   return DWARFDie();
550 }
551 
552 DWARFDie DWARFDie::getSibling() const {
553   if (isValid())
554     return U->getSibling(Die);
555   return DWARFDie();
556 }
557 
558 DWARFDie DWARFDie::getPreviousSibling() const {
559   if (isValid())
560     return U->getPreviousSibling(Die);
561   return DWARFDie();
562 }
563 
564 DWARFDie DWARFDie::getFirstChild() const {
565   if (isValid())
566     return U->getFirstChild(Die);
567   return DWARFDie();
568 }
569 
570 DWARFDie DWARFDie::getLastChild() const {
571   if (isValid())
572     return U->getLastChild(Die);
573   return DWARFDie();
574 }
575 
576 iterator_range<DWARFDie::attribute_iterator> DWARFDie::attributes() const {
577   return make_range(attribute_iterator(*this, false),
578                     attribute_iterator(*this, true));
579 }
580 
581 DWARFDie::attribute_iterator::attribute_iterator(DWARFDie D, bool End)
582     : Die(D), AttrValue(0), Index(0) {
583   auto AbbrDecl = Die.getAbbreviationDeclarationPtr();
584   assert(AbbrDecl && "Must have abbreviation declaration");
585   if (End) {
586     // This is the end iterator so we set the index to the attribute count.
587     Index = AbbrDecl->getNumAttributes();
588   } else {
589     // This is the begin iterator so we extract the value for this->Index.
590     AttrValue.Offset = D.getOffset() + AbbrDecl->getCodeByteSize();
591     updateForIndex(*AbbrDecl, 0);
592   }
593 }
594 
595 void DWARFDie::attribute_iterator::updateForIndex(
596     const DWARFAbbreviationDeclaration &AbbrDecl, uint32_t I) {
597   Index = I;
598   // AbbrDecl must be valid before calling this function.
599   auto NumAttrs = AbbrDecl.getNumAttributes();
600   if (Index < NumAttrs) {
601     AttrValue.Attr = AbbrDecl.getAttrByIndex(Index);
602     // Add the previous byte size of any previous attribute value.
603     AttrValue.Offset += AttrValue.ByteSize;
604     AttrValue.Value.setForm(AbbrDecl.getFormByIndex(Index));
605     uint32_t ParseOffset = AttrValue.Offset;
606     auto U = Die.getDwarfUnit();
607     assert(U && "Die must have valid DWARF unit");
608     bool b = AttrValue.Value.extractValue(U->getDebugInfoExtractor(),
609                                           &ParseOffset, U->getFormParams(), U);
610     (void)b;
611     assert(b && "extractValue cannot fail on fully parsed DWARF");
612     AttrValue.ByteSize = ParseOffset - AttrValue.Offset;
613   } else {
614     assert(Index == NumAttrs && "Indexes should be [0, NumAttrs) only");
615     AttrValue.clear();
616   }
617 }
618 
619 DWARFDie::attribute_iterator &DWARFDie::attribute_iterator::operator++() {
620   if (auto AbbrDecl = Die.getAbbreviationDeclarationPtr())
621     updateForIndex(*AbbrDecl, Index + 1);
622   return *this;
623 }
624