xref: /freebsd/contrib/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp (revision 6132212808e8dccedc9e5d85fea4390c2f38059a) 
1 //===- DWARFDie.cpp -------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
10 #include "llvm/ADT/None.h"
11 #include "llvm/ADT/Optional.h"
12 #include "llvm/ADT/SmallSet.h"
13 #include "llvm/ADT/StringRef.h"
14 #include "llvm/BinaryFormat/Dwarf.h"
15 #include "llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h"
16 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
17 #include "llvm/DebugInfo/DWARF/DWARFDebugRangeList.h"
18 #include "llvm/DebugInfo/DWARF/DWARFExpression.h"
19 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
20 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
21 #include "llvm/Object/ObjectFile.h"
22 #include "llvm/Support/DataExtractor.h"
23 #include "llvm/Support/Format.h"
24 #include "llvm/Support/FormatAdapters.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   if (!DumpOpts.ShowAddresses)
63     return;
64 
65   for (const DWARFAddressRange &R : Ranges) {
66     OS << '\n';
67     OS.indent(Indent);
68     R.dump(OS, AddressSize, DumpOpts, &Obj);
69   }
70 }
71 
72 static void dumpLocation(raw_ostream &OS, DWARFFormValue &FormValue,
73                          DWARFUnit *U, unsigned Indent,
74                          DIDumpOptions DumpOpts) {
75   DWARFContext &Ctx = U->getContext();
76   const MCRegisterInfo *MRI = Ctx.getRegisterInfo();
77   if (FormValue.isFormClass(DWARFFormValue::FC_Block) ||
78       FormValue.isFormClass(DWARFFormValue::FC_Exprloc)) {
79     ArrayRef<uint8_t> Expr = *FormValue.getAsBlock();
80     DataExtractor Data(StringRef((const char *)Expr.data(), Expr.size()),
81                        Ctx.isLittleEndian(), 0);
82     DWARFExpression(Data, U->getAddressByteSize(), U->getFormParams().Format)
83         .print(OS, MRI, U);
84     return;
85   }
86 
87   if (FormValue.isFormClass(DWARFFormValue::FC_SectionOffset)) {
88     uint64_t Offset = *FormValue.getAsSectionOffset();
89 
90     if (FormValue.getForm() == DW_FORM_loclistx) {
91       FormValue.dump(OS, DumpOpts);
92 
93       if (auto LoclistOffset = U->getLoclistOffset(Offset))
94         Offset = *LoclistOffset;
95       else
96         return;
97     }
98     U->getLocationTable().dumpLocationList(&Offset, OS, U->getBaseAddress(),
99                                            MRI, Ctx.getDWARFObj(), U, DumpOpts,
100                                            Indent);
101     return;
102   }
103 
104   FormValue.dump(OS, DumpOpts);
105 }
106 
107 /// Dump the name encoded in the type tag.
108 static void dumpTypeTagName(raw_ostream &OS, dwarf::Tag T) {
109   StringRef TagStr = TagString(T);
110   if (!TagStr.startswith("DW_TAG_") || !TagStr.endswith("_type"))
111     return;
112   OS << TagStr.substr(7, TagStr.size() - 12) << " ";
113 }
114 
115 static void dumpArrayType(raw_ostream &OS, const DWARFDie &D) {
116   Optional<uint64_t> Bound;
117   for (const DWARFDie &C : D.children())
118     if (C.getTag() == DW_TAG_subrange_type) {
119       Optional<uint64_t> LB;
120       Optional<uint64_t> Count;
121       Optional<uint64_t> UB;
122       Optional<unsigned> DefaultLB;
123       if (Optional<DWARFFormValue> L = C.find(DW_AT_lower_bound))
124         LB = L->getAsUnsignedConstant();
125       if (Optional<DWARFFormValue> CountV = C.find(DW_AT_count))
126         Count = CountV->getAsUnsignedConstant();
127       if (Optional<DWARFFormValue> UpperV = C.find(DW_AT_upper_bound))
128         UB = UpperV->getAsUnsignedConstant();
129       if (Optional<DWARFFormValue> LV =
130               D.getDwarfUnit()->getUnitDIE().find(DW_AT_language))
131         if (Optional<uint64_t> LC = LV->getAsUnsignedConstant())
132           if ((DefaultLB =
133                    LanguageLowerBound(static_cast<dwarf::SourceLanguage>(*LC))))
134             if (LB && *LB == *DefaultLB)
135               LB = None;
136       if (!LB && !Count && !UB)
137         OS << "[]";
138       else if (!LB && (Count || UB) && DefaultLB)
139         OS << '[' << (Count ? *Count : *UB - *DefaultLB + 1) << ']';
140       else {
141         OS << "[[";
142         if (LB)
143           OS << *LB;
144         else
145           OS << '?';
146         OS << ", ";
147         if (Count)
148           if (LB)
149             OS << *LB + *Count;
150           else
151             OS << "? + " << *Count;
152         else if (UB)
153           OS << *UB + 1;
154         else
155           OS << '?';
156         OS << ")]";
157       }
158     }
159 }
160 
161 /// Recursively dump the DIE type name when applicable.
162 static void dumpTypeName(raw_ostream &OS, const DWARFDie &D) {
163   if (!D.isValid())
164     return;
165 
166   if (const char *Name = D.getName(DINameKind::LinkageName)) {
167     OS << Name;
168     return;
169   }
170 
171   // FIXME: We should have pretty printers per language. Currently we print
172   // everything as if it was C++ and fall back to the TAG type name.
173   const dwarf::Tag T = D.getTag();
174   switch (T) {
175   case DW_TAG_array_type:
176   case DW_TAG_pointer_type:
177   case DW_TAG_ptr_to_member_type:
178   case DW_TAG_reference_type:
179   case DW_TAG_rvalue_reference_type:
180   case DW_TAG_subroutine_type:
181     break;
182   default:
183     dumpTypeTagName(OS, T);
184   }
185 
186   // Follow the DW_AT_type if possible.
187   DWARFDie TypeDie = D.getAttributeValueAsReferencedDie(DW_AT_type);
188   dumpTypeName(OS, TypeDie);
189 
190   switch (T) {
191   case DW_TAG_subroutine_type: {
192     if (!TypeDie)
193       OS << "void";
194     OS << '(';
195     bool First = true;
196     for (const DWARFDie &C : D.children()) {
197       if (C.getTag() == DW_TAG_formal_parameter) {
198         if (!First)
199           OS << ", ";
200         First = false;
201         dumpTypeName(OS, C.getAttributeValueAsReferencedDie(DW_AT_type));
202       }
203     }
204     OS << ')';
205     break;
206   }
207   case DW_TAG_array_type: {
208     dumpArrayType(OS, D);
209     break;
210   }
211   case DW_TAG_pointer_type:
212     OS << '*';
213     break;
214   case DW_TAG_ptr_to_member_type:
215     if (DWARFDie Cont =
216             D.getAttributeValueAsReferencedDie(DW_AT_containing_type)) {
217       dumpTypeName(OS << ' ', Cont);
218       OS << "::";
219     }
220     OS << '*';
221     break;
222   case DW_TAG_reference_type:
223     OS << '&';
224     break;
225   case DW_TAG_rvalue_reference_type:
226     OS << "&&";
227     break;
228   default:
229     break;
230   }
231 }
232 
233 static void dumpAttribute(raw_ostream &OS, const DWARFDie &Die,
234                           uint64_t *OffsetPtr, dwarf::Attribute Attr,
235                           dwarf::Form Form, unsigned Indent,
236                           DIDumpOptions DumpOpts) {
237   if (!Die.isValid())
238     return;
239   const char BaseIndent[] = "            ";
240   OS << BaseIndent;
241   OS.indent(Indent + 2);
242   WithColor(OS, HighlightColor::Attribute) << formatv("{0}", Attr);
243 
244   if (DumpOpts.Verbose || DumpOpts.ShowForm)
245     OS << formatv(" [{0}]", Form);
246 
247   DWARFUnit *U = Die.getDwarfUnit();
248   DWARFFormValue FormValue = DWARFFormValue::createFromUnit(Form, U, OffsetPtr);
249 
250   OS << "\t(";
251 
252   StringRef Name;
253   std::string File;
254   auto Color = HighlightColor::Enumerator;
255   if (Attr == DW_AT_decl_file || Attr == DW_AT_call_file) {
256     Color = HighlightColor::String;
257     if (const auto *LT = U->getContext().getLineTableForUnit(U))
258       if (LT->getFileNameByIndex(
259               FormValue.getAsUnsignedConstant().getValue(),
260               U->getCompilationDir(),
261               DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, File)) {
262         File = '"' + File + '"';
263         Name = File;
264       }
265   } else if (Optional<uint64_t> Val = FormValue.getAsUnsignedConstant())
266     Name = AttributeValueString(Attr, *Val);
267 
268   if (!Name.empty())
269     WithColor(OS, Color) << Name;
270   else if (Attr == DW_AT_decl_line || Attr == DW_AT_call_line)
271     OS << *FormValue.getAsUnsignedConstant();
272   else if (Attr == DW_AT_high_pc && !DumpOpts.ShowForm && !DumpOpts.Verbose &&
273            FormValue.getAsUnsignedConstant()) {
274     if (DumpOpts.ShowAddresses) {
275       // Print the actual address rather than the offset.
276       uint64_t LowPC, HighPC, Index;
277       if (Die.getLowAndHighPC(LowPC, HighPC, Index))
278         OS << format("0x%016" PRIx64, HighPC);
279       else
280         FormValue.dump(OS, DumpOpts);
281     }
282   } else if (Form == dwarf::Form::DW_FORM_exprloc ||
283              DWARFAttribute::mayHaveLocationDescription(Attr))
284     dumpLocation(OS, FormValue, U, sizeof(BaseIndent) + Indent + 4, DumpOpts);
285   else
286     FormValue.dump(OS, DumpOpts);
287 
288   std::string Space = DumpOpts.ShowAddresses ? " " : "";
289 
290   // We have dumped the attribute raw value. For some attributes
291   // having both the raw value and the pretty-printed value is
292   // interesting. These attributes are handled below.
293   if (Attr == DW_AT_specification || Attr == DW_AT_abstract_origin) {
294     if (const char *Name =
295             Die.getAttributeValueAsReferencedDie(FormValue).getName(
296                 DINameKind::LinkageName))
297       OS << Space << "\"" << Name << '\"';
298   } else if (Attr == DW_AT_type) {
299     OS << Space << "\"";
300     dumpTypeName(OS, Die.getAttributeValueAsReferencedDie(FormValue));
301     OS << '"';
302   } else if (Attr == DW_AT_APPLE_property_attribute) {
303     if (Optional<uint64_t> OptVal = FormValue.getAsUnsignedConstant())
304       dumpApplePropertyAttribute(OS, *OptVal);
305   } else if (Attr == DW_AT_ranges) {
306     const DWARFObject &Obj = Die.getDwarfUnit()->getContext().getDWARFObj();
307     // For DW_FORM_rnglistx we need to dump the offset separately, since
308     // we have only dumped the index so far.
309     if (FormValue.getForm() == DW_FORM_rnglistx)
310       if (auto RangeListOffset =
311               U->getRnglistOffset(*FormValue.getAsSectionOffset())) {
312         DWARFFormValue FV = DWARFFormValue::createFromUValue(
313             dwarf::DW_FORM_sec_offset, *RangeListOffset);
314         FV.dump(OS, DumpOpts);
315       }
316     if (auto RangesOrError = Die.getAddressRanges())
317       dumpRanges(Obj, OS, RangesOrError.get(), U->getAddressByteSize(),
318                  sizeof(BaseIndent) + Indent + 4, DumpOpts);
319     else
320       DumpOpts.RecoverableErrorHandler(createStringError(
321           errc::invalid_argument, "decoding address ranges: %s",
322           toString(RangesOrError.takeError()).c_str()));
323   }
324 
325   OS << ")\n";
326 }
327 
328 bool DWARFDie::isSubprogramDIE() const { return getTag() == DW_TAG_subprogram; }
329 
330 bool DWARFDie::isSubroutineDIE() const {
331   auto Tag = getTag();
332   return Tag == DW_TAG_subprogram || Tag == DW_TAG_inlined_subroutine;
333 }
334 
335 Optional<DWARFFormValue> DWARFDie::find(dwarf::Attribute Attr) const {
336   if (!isValid())
337     return None;
338   auto AbbrevDecl = getAbbreviationDeclarationPtr();
339   if (AbbrevDecl)
340     return AbbrevDecl->getAttributeValue(getOffset(), Attr, *U);
341   return None;
342 }
343 
344 Optional<DWARFFormValue>
345 DWARFDie::find(ArrayRef<dwarf::Attribute> Attrs) const {
346   if (!isValid())
347     return None;
348   auto AbbrevDecl = getAbbreviationDeclarationPtr();
349   if (AbbrevDecl) {
350     for (auto Attr : Attrs) {
351       if (auto Value = AbbrevDecl->getAttributeValue(getOffset(), Attr, *U))
352         return Value;
353     }
354   }
355   return None;
356 }
357 
358 Optional<DWARFFormValue>
359 DWARFDie::findRecursively(ArrayRef<dwarf::Attribute> Attrs) const {
360   SmallVector<DWARFDie, 3> Worklist;
361   Worklist.push_back(*this);
362 
363   // Keep track if DIEs already seen to prevent infinite recursion.
364   // Empirically we rarely see a depth of more than 3 when dealing with valid
365   // DWARF. This corresponds to following the DW_AT_abstract_origin and
366   // DW_AT_specification just once.
367   SmallSet<DWARFDie, 3> Seen;
368   Seen.insert(*this);
369 
370   while (!Worklist.empty()) {
371     DWARFDie Die = Worklist.back();
372     Worklist.pop_back();
373 
374     if (!Die.isValid())
375       continue;
376 
377     if (auto Value = Die.find(Attrs))
378       return Value;
379 
380     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_abstract_origin))
381       if (Seen.insert(D).second)
382         Worklist.push_back(D);
383 
384     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_specification))
385       if (Seen.insert(D).second)
386         Worklist.push_back(D);
387   }
388 
389   return None;
390 }
391 
392 DWARFDie
393 DWARFDie::getAttributeValueAsReferencedDie(dwarf::Attribute Attr) const {
394   if (Optional<DWARFFormValue> F = find(Attr))
395     return getAttributeValueAsReferencedDie(*F);
396   return DWARFDie();
397 }
398 
399 DWARFDie
400 DWARFDie::getAttributeValueAsReferencedDie(const DWARFFormValue &V) const {
401   if (auto SpecRef = V.getAsRelativeReference()) {
402     if (SpecRef->Unit)
403       return SpecRef->Unit->getDIEForOffset(SpecRef->Unit->getOffset() + SpecRef->Offset);
404     if (auto SpecUnit = U->getUnitVector().getUnitForOffset(SpecRef->Offset))
405       return SpecUnit->getDIEForOffset(SpecRef->Offset);
406   }
407   return DWARFDie();
408 }
409 
410 Optional<uint64_t> DWARFDie::getRangesBaseAttribute() const {
411   return toSectionOffset(find({DW_AT_rnglists_base, DW_AT_GNU_ranges_base}));
412 }
413 
414 Optional<uint64_t> DWARFDie::getLocBaseAttribute() const {
415   return toSectionOffset(find(DW_AT_loclists_base));
416 }
417 
418 Optional<uint64_t> DWARFDie::getHighPC(uint64_t LowPC) const {
419   if (auto FormValue = find(DW_AT_high_pc)) {
420     if (auto Address = FormValue->getAsAddress()) {
421       // High PC is an address.
422       return Address;
423     }
424     if (auto Offset = FormValue->getAsUnsignedConstant()) {
425       // High PC is an offset from LowPC.
426       return LowPC + *Offset;
427     }
428   }
429   return None;
430 }
431 
432 bool DWARFDie::getLowAndHighPC(uint64_t &LowPC, uint64_t &HighPC,
433                                uint64_t &SectionIndex) const {
434   auto F = find(DW_AT_low_pc);
435   auto LowPcAddr = toSectionedAddress(F);
436   if (!LowPcAddr)
437     return false;
438   if (auto HighPcAddr = getHighPC(LowPcAddr->Address)) {
439     LowPC = LowPcAddr->Address;
440     HighPC = *HighPcAddr;
441     SectionIndex = LowPcAddr->SectionIndex;
442     return true;
443   }
444   return false;
445 }
446 
447 Expected<DWARFAddressRangesVector> DWARFDie::getAddressRanges() const {
448   if (isNULL())
449     return DWARFAddressRangesVector();
450   // Single range specified by low/high PC.
451   uint64_t LowPC, HighPC, Index;
452   if (getLowAndHighPC(LowPC, HighPC, Index))
453     return DWARFAddressRangesVector{{LowPC, HighPC, Index}};
454 
455   Optional<DWARFFormValue> Value = find(DW_AT_ranges);
456   if (Value) {
457     if (Value->getForm() == DW_FORM_rnglistx)
458       return U->findRnglistFromIndex(*Value->getAsSectionOffset());
459     return U->findRnglistFromOffset(*Value->getAsSectionOffset());
460   }
461   return DWARFAddressRangesVector();
462 }
463 
464 void DWARFDie::collectChildrenAddressRanges(
465     DWARFAddressRangesVector &Ranges) const {
466   if (isNULL())
467     return;
468   if (isSubprogramDIE()) {
469     if (auto DIERangesOrError = getAddressRanges())
470       Ranges.insert(Ranges.end(), DIERangesOrError.get().begin(),
471                     DIERangesOrError.get().end());
472     else
473       llvm::consumeError(DIERangesOrError.takeError());
474   }
475 
476   for (auto Child : children())
477     Child.collectChildrenAddressRanges(Ranges);
478 }
479 
480 bool DWARFDie::addressRangeContainsAddress(const uint64_t Address) const {
481   auto RangesOrError = getAddressRanges();
482   if (!RangesOrError) {
483     llvm::consumeError(RangesOrError.takeError());
484     return false;
485   }
486 
487   for (const auto &R : RangesOrError.get())
488     if (R.LowPC <= Address && Address < R.HighPC)
489       return true;
490   return false;
491 }
492 
493 Expected<DWARFLocationExpressionsVector>
494 DWARFDie::getLocations(dwarf::Attribute Attr) const {
495   Optional<DWARFFormValue> Location = find(Attr);
496   if (!Location)
497     return createStringError(inconvertibleErrorCode(), "No %s",
498                              dwarf::AttributeString(Attr).data());
499 
500   if (Optional<uint64_t> Off = Location->getAsSectionOffset()) {
501     uint64_t Offset = *Off;
502 
503     if (Location->getForm() == DW_FORM_loclistx) {
504       if (auto LoclistOffset = U->getLoclistOffset(Offset))
505         Offset = *LoclistOffset;
506       else
507         return createStringError(inconvertibleErrorCode(),
508                                  "Loclist table not found");
509     }
510     return U->findLoclistFromOffset(Offset);
511   }
512 
513   if (Optional<ArrayRef<uint8_t>> Expr = Location->getAsBlock()) {
514     return DWARFLocationExpressionsVector{
515         DWARFLocationExpression{None, to_vector<4>(*Expr)}};
516   }
517 
518   return createStringError(
519       inconvertibleErrorCode(), "Unsupported %s encoding: %s",
520       dwarf::AttributeString(Attr).data(),
521       dwarf::FormEncodingString(Location->getForm()).data());
522 }
523 
524 const char *DWARFDie::getSubroutineName(DINameKind Kind) const {
525   if (!isSubroutineDIE())
526     return nullptr;
527   return getName(Kind);
528 }
529 
530 const char *DWARFDie::getName(DINameKind Kind) const {
531   if (!isValid() || Kind == DINameKind::None)
532     return nullptr;
533   // Try to get mangled name only if it was asked for.
534   if (Kind == DINameKind::LinkageName) {
535     if (auto Name = getLinkageName())
536       return Name;
537   }
538   return getShortName();
539 }
540 
541 const char *DWARFDie::getShortName() const {
542   if (!isValid())
543     return nullptr;
544 
545   return dwarf::toString(findRecursively(dwarf::DW_AT_name), nullptr);
546 }
547 
548 const char *DWARFDie::getLinkageName() const {
549   if (!isValid())
550     return nullptr;
551 
552   return dwarf::toString(findRecursively({dwarf::DW_AT_MIPS_linkage_name,
553                                           dwarf::DW_AT_linkage_name}),
554                          nullptr);
555 }
556 
557 uint64_t DWARFDie::getDeclLine() const {
558   return toUnsigned(findRecursively(DW_AT_decl_line), 0);
559 }
560 
561 void DWARFDie::getCallerFrame(uint32_t &CallFile, uint32_t &CallLine,
562                               uint32_t &CallColumn,
563                               uint32_t &CallDiscriminator) const {
564   CallFile = toUnsigned(find(DW_AT_call_file), 0);
565   CallLine = toUnsigned(find(DW_AT_call_line), 0);
566   CallColumn = toUnsigned(find(DW_AT_call_column), 0);
567   CallDiscriminator = toUnsigned(find(DW_AT_GNU_discriminator), 0);
568 }
569 
570 /// Helper to dump a DIE with all of its parents, but no siblings.
571 static unsigned dumpParentChain(DWARFDie Die, raw_ostream &OS, unsigned Indent,
572                                 DIDumpOptions DumpOpts, unsigned Depth = 0) {
573   if (!Die)
574     return Indent;
575   if (DumpOpts.ParentRecurseDepth > 0 && Depth >= DumpOpts.ParentRecurseDepth)
576     return Indent;
577   Indent = dumpParentChain(Die.getParent(), OS, Indent, DumpOpts, Depth + 1);
578   Die.dump(OS, Indent, DumpOpts);
579   return Indent + 2;
580 }
581 
582 void DWARFDie::dump(raw_ostream &OS, unsigned Indent,
583                     DIDumpOptions DumpOpts) const {
584   if (!isValid())
585     return;
586   DWARFDataExtractor debug_info_data = U->getDebugInfoExtractor();
587   const uint64_t Offset = getOffset();
588   uint64_t offset = Offset;
589   if (DumpOpts.ShowParents) {
590     DIDumpOptions ParentDumpOpts = DumpOpts;
591     ParentDumpOpts.ShowParents = false;
592     ParentDumpOpts.ShowChildren = false;
593     Indent = dumpParentChain(getParent(), OS, Indent, ParentDumpOpts);
594   }
595 
596   if (debug_info_data.isValidOffset(offset)) {
597     uint32_t abbrCode = debug_info_data.getULEB128(&offset);
598     if (DumpOpts.ShowAddresses)
599       WithColor(OS, HighlightColor::Address).get()
600           << format("\n0x%8.8" PRIx64 ": ", Offset);
601 
602     if (abbrCode) {
603       auto AbbrevDecl = getAbbreviationDeclarationPtr();
604       if (AbbrevDecl) {
605         WithColor(OS, HighlightColor::Tag).get().indent(Indent)
606             << formatv("{0}", getTag());
607         if (DumpOpts.Verbose)
608           OS << format(" [%u] %c", abbrCode,
609                        AbbrevDecl->hasChildren() ? '*' : ' ');
610         OS << '\n';
611 
612         // Dump all data in the DIE for the attributes.
613         for (const auto &AttrSpec : AbbrevDecl->attributes()) {
614           if (AttrSpec.Form == DW_FORM_implicit_const) {
615             // We are dumping .debug_info section ,
616             // implicit_const attribute values are not really stored here,
617             // but in .debug_abbrev section. So we just skip such attrs.
618             continue;
619           }
620           dumpAttribute(OS, *this, &offset, AttrSpec.Attr, AttrSpec.Form,
621                         Indent, DumpOpts);
622         }
623 
624         DWARFDie child = getFirstChild();
625         if (DumpOpts.ShowChildren && DumpOpts.ChildRecurseDepth > 0 && child) {
626           DumpOpts.ChildRecurseDepth--;
627           DIDumpOptions ChildDumpOpts = DumpOpts;
628           ChildDumpOpts.ShowParents = false;
629           while (child) {
630             child.dump(OS, Indent + 2, ChildDumpOpts);
631             child = child.getSibling();
632           }
633         }
634       } else {
635         OS << "Abbreviation code not found in 'debug_abbrev' class for code: "
636            << abbrCode << '\n';
637       }
638     } else {
639       OS.indent(Indent) << "NULL\n";
640     }
641   }
642 }
643 
644 LLVM_DUMP_METHOD void DWARFDie::dump() const { dump(llvm::errs(), 0); }
645 
646 DWARFDie DWARFDie::getParent() const {
647   if (isValid())
648     return U->getParent(Die);
649   return DWARFDie();
650 }
651 
652 DWARFDie DWARFDie::getSibling() const {
653   if (isValid())
654     return U->getSibling(Die);
655   return DWARFDie();
656 }
657 
658 DWARFDie DWARFDie::getPreviousSibling() const {
659   if (isValid())
660     return U->getPreviousSibling(Die);
661   return DWARFDie();
662 }
663 
664 DWARFDie DWARFDie::getFirstChild() const {
665   if (isValid())
666     return U->getFirstChild(Die);
667   return DWARFDie();
668 }
669 
670 DWARFDie DWARFDie::getLastChild() const {
671   if (isValid())
672     return U->getLastChild(Die);
673   return DWARFDie();
674 }
675 
676 iterator_range<DWARFDie::attribute_iterator> DWARFDie::attributes() const {
677   return make_range(attribute_iterator(*this, false),
678                     attribute_iterator(*this, true));
679 }
680 
681 DWARFDie::attribute_iterator::attribute_iterator(DWARFDie D, bool End)
682     : Die(D), Index(0) {
683   auto AbbrDecl = Die.getAbbreviationDeclarationPtr();
684   assert(AbbrDecl && "Must have abbreviation declaration");
685   if (End) {
686     // This is the end iterator so we set the index to the attribute count.
687     Index = AbbrDecl->getNumAttributes();
688   } else {
689     // This is the begin iterator so we extract the value for this->Index.
690     AttrValue.Offset = D.getOffset() + AbbrDecl->getCodeByteSize();
691     updateForIndex(*AbbrDecl, 0);
692   }
693 }
694 
695 void DWARFDie::attribute_iterator::updateForIndex(
696     const DWARFAbbreviationDeclaration &AbbrDecl, uint32_t I) {
697   Index = I;
698   // AbbrDecl must be valid before calling this function.
699   auto NumAttrs = AbbrDecl.getNumAttributes();
700   if (Index < NumAttrs) {
701     AttrValue.Attr = AbbrDecl.getAttrByIndex(Index);
702     // Add the previous byte size of any previous attribute value.
703     AttrValue.Offset += AttrValue.ByteSize;
704     uint64_t ParseOffset = AttrValue.Offset;
705     auto U = Die.getDwarfUnit();
706     assert(U && "Die must have valid DWARF unit");
707     AttrValue.Value = DWARFFormValue::createFromUnit(
708         AbbrDecl.getFormByIndex(Index), U, &ParseOffset);
709     AttrValue.ByteSize = ParseOffset - AttrValue.Offset;
710   } else {
711     assert(Index == NumAttrs && "Indexes should be [0, NumAttrs) only");
712     AttrValue = {};
713   }
714 }
715 
716 DWARFDie::attribute_iterator &DWARFDie::attribute_iterator::operator++() {
717   if (auto AbbrDecl = Die.getAbbreviationDeclarationPtr())
718     updateForIndex(*AbbrDecl, Index + 1);
719   return *this;
720 }
721 
722 bool DWARFAttribute::mayHaveLocationDescription(dwarf::Attribute Attr) {
723   switch (Attr) {
724   // From the DWARF v5 specification.
725   case DW_AT_location:
726   case DW_AT_byte_size:
727   case DW_AT_bit_size:
728   case DW_AT_string_length:
729   case DW_AT_lower_bound:
730   case DW_AT_return_addr:
731   case DW_AT_bit_stride:
732   case DW_AT_upper_bound:
733   case DW_AT_count:
734   case DW_AT_data_member_location:
735   case DW_AT_frame_base:
736   case DW_AT_segment:
737   case DW_AT_static_link:
738   case DW_AT_use_location:
739   case DW_AT_vtable_elem_location:
740   case DW_AT_allocated:
741   case DW_AT_associated:
742   case DW_AT_byte_stride:
743   case DW_AT_rank:
744   case DW_AT_call_value:
745   case DW_AT_call_origin:
746   case DW_AT_call_target:
747   case DW_AT_call_target_clobbered:
748   case DW_AT_call_data_location:
749   case DW_AT_call_data_value:
750   // Extensions.
751   case DW_AT_GNU_call_site_value:
752   case DW_AT_GNU_call_site_target:
753     return true;
754   default:
755     return false;
756   }
757 }
758