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, DumpOpts, 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   for (const DWARFDie &C : D.children())
117     if (C.getTag() == DW_TAG_subrange_type) {
118       Optional<uint64_t> LB;
119       Optional<uint64_t> Count;
120       Optional<uint64_t> UB;
121       Optional<unsigned> DefaultLB;
122       if (Optional<DWARFFormValue> L = C.find(DW_AT_lower_bound))
123         LB = L->getAsUnsignedConstant();
124       if (Optional<DWARFFormValue> CountV = C.find(DW_AT_count))
125         Count = CountV->getAsUnsignedConstant();
126       if (Optional<DWARFFormValue> UpperV = C.find(DW_AT_upper_bound))
127         UB = UpperV->getAsUnsignedConstant();
128       if (Optional<DWARFFormValue> LV =
129               D.getDwarfUnit()->getUnitDIE().find(DW_AT_language))
130         if (Optional<uint64_t> LC = LV->getAsUnsignedConstant())
131           if ((DefaultLB =
132                    LanguageLowerBound(static_cast<dwarf::SourceLanguage>(*LC))))
133             if (LB && *LB == *DefaultLB)
134               LB = None;
135       if (!LB && !Count && !UB)
136         OS << "[]";
137       else if (!LB && (Count || UB) && DefaultLB)
138         OS << '[' << (Count ? *Count : *UB - *DefaultLB + 1) << ']';
139       else {
140         OS << "[[";
141         if (LB)
142           OS << *LB;
143         else
144           OS << '?';
145         OS << ", ";
146         if (Count)
147           if (LB)
148             OS << *LB + *Count;
149           else
150             OS << "? + " << *Count;
151         else if (UB)
152           OS << *UB + 1;
153         else
154           OS << '?';
155         OS << ")]";
156       }
157     }
158 }
159 
160 /// Recursively dump the DIE type name when applicable.
161 static void dumpTypeName(raw_ostream &OS, const DWARFDie &D) {
162   if (!D.isValid())
163     return;
164 
165   if (const char *Name = D.getName(DINameKind::LinkageName)) {
166     OS << Name;
167     return;
168   }
169 
170   // FIXME: We should have pretty printers per language. Currently we print
171   // everything as if it was C++ and fall back to the TAG type name.
172   const dwarf::Tag T = D.getTag();
173   switch (T) {
174   case DW_TAG_array_type:
175   case DW_TAG_pointer_type:
176   case DW_TAG_ptr_to_member_type:
177   case DW_TAG_reference_type:
178   case DW_TAG_rvalue_reference_type:
179   case DW_TAG_subroutine_type:
180     break;
181   default:
182     dumpTypeTagName(OS, T);
183   }
184 
185   // Follow the DW_AT_type if possible.
186   DWARFDie TypeDie = D.getAttributeValueAsReferencedDie(DW_AT_type);
187   dumpTypeName(OS, TypeDie);
188 
189   switch (T) {
190   case DW_TAG_subroutine_type: {
191     if (!TypeDie)
192       OS << "void";
193     OS << '(';
194     bool First = true;
195     for (const DWARFDie &C : D.children()) {
196       if (C.getTag() == DW_TAG_formal_parameter) {
197         if (!First)
198           OS << ", ";
199         First = false;
200         dumpTypeName(OS, C.getAttributeValueAsReferencedDie(DW_AT_type));
201       }
202     }
203     OS << ')';
204     break;
205   }
206   case DW_TAG_array_type: {
207     dumpArrayType(OS, D);
208     break;
209   }
210   case DW_TAG_pointer_type:
211     OS << '*';
212     break;
213   case DW_TAG_ptr_to_member_type:
214     if (DWARFDie Cont =
215             D.getAttributeValueAsReferencedDie(DW_AT_containing_type)) {
216       dumpTypeName(OS << ' ', Cont);
217       OS << "::";
218     }
219     OS << '*';
220     break;
221   case DW_TAG_reference_type:
222     OS << '&';
223     break;
224   case DW_TAG_rvalue_reference_type:
225     OS << "&&";
226     break;
227   default:
228     break;
229   }
230 }
231 
232 static void dumpAttribute(raw_ostream &OS, const DWARFDie &Die,
233                           uint64_t *OffsetPtr, dwarf::Attribute Attr,
234                           dwarf::Form Form, unsigned Indent,
235                           DIDumpOptions DumpOpts) {
236   if (!Die.isValid())
237     return;
238   const char BaseIndent[] = "            ";
239   OS << BaseIndent;
240   OS.indent(Indent + 2);
241   WithColor(OS, HighlightColor::Attribute) << formatv("{0}", Attr);
242 
243   if (DumpOpts.Verbose || DumpOpts.ShowForm)
244     OS << formatv(" [{0}]", Form);
245 
246   DWARFUnit *U = Die.getDwarfUnit();
247   DWARFFormValue FormValue = DWARFFormValue::createFromUnit(Form, U, OffsetPtr);
248 
249   OS << "\t(";
250 
251   StringRef Name;
252   std::string File;
253   auto Color = HighlightColor::Enumerator;
254   if (Attr == DW_AT_decl_file || Attr == DW_AT_call_file) {
255     Color = HighlightColor::String;
256     if (const auto *LT = U->getContext().getLineTableForUnit(U))
257       if (LT->getFileNameByIndex(
258               FormValue.getAsUnsignedConstant().getValue(),
259               U->getCompilationDir(),
260               DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, File)) {
261         File = '"' + File + '"';
262         Name = File;
263       }
264   } else if (Optional<uint64_t> Val = FormValue.getAsUnsignedConstant())
265     Name = AttributeValueString(Attr, *Val);
266 
267   if (!Name.empty())
268     WithColor(OS, Color) << Name;
269   else if (Attr == DW_AT_decl_line || Attr == DW_AT_call_line)
270     OS << *FormValue.getAsUnsignedConstant();
271   else if (Attr == DW_AT_low_pc &&
272            (FormValue.getAsAddress() ==
273             dwarf::computeTombstoneAddress(U->getAddressByteSize()))) {
274     if (DumpOpts.Verbose) {
275       FormValue.dump(OS, DumpOpts);
276       OS << " (";
277     }
278     OS << "dead code";
279     if (DumpOpts.Verbose)
280       OS << ')';
281   } else if (Attr == DW_AT_high_pc && !DumpOpts.ShowForm && !DumpOpts.Verbose &&
282              FormValue.getAsUnsignedConstant()) {
283     if (DumpOpts.ShowAddresses) {
284       // Print the actual address rather than the offset.
285       uint64_t LowPC, HighPC, Index;
286       if (Die.getLowAndHighPC(LowPC, HighPC, Index))
287         DWARFFormValue::dumpAddress(OS, U->getAddressByteSize(), HighPC);
288       else
289         FormValue.dump(OS, DumpOpts);
290     }
291   } else if (Form == dwarf::Form::DW_FORM_exprloc ||
292              DWARFAttribute::mayHaveLocationDescription(Attr))
293     dumpLocation(OS, FormValue, U, sizeof(BaseIndent) + Indent + 4, DumpOpts);
294   else
295     FormValue.dump(OS, DumpOpts);
296 
297   std::string Space = DumpOpts.ShowAddresses ? " " : "";
298 
299   // We have dumped the attribute raw value. For some attributes
300   // having both the raw value and the pretty-printed value is
301   // interesting. These attributes are handled below.
302   if (Attr == DW_AT_specification || Attr == DW_AT_abstract_origin) {
303     if (const char *Name =
304             Die.getAttributeValueAsReferencedDie(FormValue).getName(
305                 DINameKind::LinkageName))
306       OS << Space << "\"" << Name << '\"';
307   } else if (Attr == DW_AT_type) {
308     OS << Space << "\"";
309     dumpTypeName(OS, Die.getAttributeValueAsReferencedDie(FormValue));
310     OS << '"';
311   } else if (Attr == DW_AT_APPLE_property_attribute) {
312     if (Optional<uint64_t> OptVal = FormValue.getAsUnsignedConstant())
313       dumpApplePropertyAttribute(OS, *OptVal);
314   } else if (Attr == DW_AT_ranges) {
315     const DWARFObject &Obj = Die.getDwarfUnit()->getContext().getDWARFObj();
316     // For DW_FORM_rnglistx we need to dump the offset separately, since
317     // we have only dumped the index so far.
318     if (FormValue.getForm() == DW_FORM_rnglistx)
319       if (auto RangeListOffset =
320               U->getRnglistOffset(*FormValue.getAsSectionOffset())) {
321         DWARFFormValue FV = DWARFFormValue::createFromUValue(
322             dwarf::DW_FORM_sec_offset, *RangeListOffset);
323         FV.dump(OS, DumpOpts);
324       }
325     if (auto RangesOrError = Die.getAddressRanges())
326       dumpRanges(Obj, OS, RangesOrError.get(), U->getAddressByteSize(),
327                  sizeof(BaseIndent) + Indent + 4, DumpOpts);
328     else
329       DumpOpts.RecoverableErrorHandler(createStringError(
330           errc::invalid_argument, "decoding address ranges: %s",
331           toString(RangesOrError.takeError()).c_str()));
332   }
333 
334   OS << ")\n";
335 }
336 
337 bool DWARFDie::isSubprogramDIE() const { return getTag() == DW_TAG_subprogram; }
338 
339 bool DWARFDie::isSubroutineDIE() const {
340   auto Tag = getTag();
341   return Tag == DW_TAG_subprogram || Tag == DW_TAG_inlined_subroutine;
342 }
343 
344 Optional<DWARFFormValue> DWARFDie::find(dwarf::Attribute Attr) const {
345   if (!isValid())
346     return None;
347   auto AbbrevDecl = getAbbreviationDeclarationPtr();
348   if (AbbrevDecl)
349     return AbbrevDecl->getAttributeValue(getOffset(), Attr, *U);
350   return None;
351 }
352 
353 Optional<DWARFFormValue>
354 DWARFDie::find(ArrayRef<dwarf::Attribute> Attrs) const {
355   if (!isValid())
356     return None;
357   auto AbbrevDecl = getAbbreviationDeclarationPtr();
358   if (AbbrevDecl) {
359     for (auto Attr : Attrs) {
360       if (auto Value = AbbrevDecl->getAttributeValue(getOffset(), Attr, *U))
361         return Value;
362     }
363   }
364   return None;
365 }
366 
367 Optional<DWARFFormValue>
368 DWARFDie::findRecursively(ArrayRef<dwarf::Attribute> Attrs) const {
369   SmallVector<DWARFDie, 3> Worklist;
370   Worklist.push_back(*this);
371 
372   // Keep track if DIEs already seen to prevent infinite recursion.
373   // Empirically we rarely see a depth of more than 3 when dealing with valid
374   // DWARF. This corresponds to following the DW_AT_abstract_origin and
375   // DW_AT_specification just once.
376   SmallSet<DWARFDie, 3> Seen;
377   Seen.insert(*this);
378 
379   while (!Worklist.empty()) {
380     DWARFDie Die = Worklist.back();
381     Worklist.pop_back();
382 
383     if (!Die.isValid())
384       continue;
385 
386     if (auto Value = Die.find(Attrs))
387       return Value;
388 
389     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_abstract_origin))
390       if (Seen.insert(D).second)
391         Worklist.push_back(D);
392 
393     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_specification))
394       if (Seen.insert(D).second)
395         Worklist.push_back(D);
396   }
397 
398   return None;
399 }
400 
401 DWARFDie
402 DWARFDie::getAttributeValueAsReferencedDie(dwarf::Attribute Attr) const {
403   if (Optional<DWARFFormValue> F = find(Attr))
404     return getAttributeValueAsReferencedDie(*F);
405   return DWARFDie();
406 }
407 
408 DWARFDie
409 DWARFDie::getAttributeValueAsReferencedDie(const DWARFFormValue &V) const {
410   if (auto SpecRef = V.getAsRelativeReference()) {
411     if (SpecRef->Unit)
412       return SpecRef->Unit->getDIEForOffset(SpecRef->Unit->getOffset() + SpecRef->Offset);
413     if (auto SpecUnit = U->getUnitVector().getUnitForOffset(SpecRef->Offset))
414       return SpecUnit->getDIEForOffset(SpecRef->Offset);
415   }
416   return DWARFDie();
417 }
418 
419 Optional<uint64_t> DWARFDie::getRangesBaseAttribute() const {
420   return toSectionOffset(find({DW_AT_rnglists_base, DW_AT_GNU_ranges_base}));
421 }
422 
423 Optional<uint64_t> DWARFDie::getLocBaseAttribute() const {
424   return toSectionOffset(find(DW_AT_loclists_base));
425 }
426 
427 Optional<uint64_t> DWARFDie::getHighPC(uint64_t LowPC) const {
428   uint64_t Tombstone = dwarf::computeTombstoneAddress(U->getAddressByteSize());
429   if (LowPC == Tombstone)
430     return None;
431   if (auto FormValue = find(DW_AT_high_pc)) {
432     if (auto Address = FormValue->getAsAddress()) {
433       // High PC is an address.
434       return Address;
435     }
436     if (auto Offset = FormValue->getAsUnsignedConstant()) {
437       // High PC is an offset from LowPC.
438       return LowPC + *Offset;
439     }
440   }
441   return None;
442 }
443 
444 bool DWARFDie::getLowAndHighPC(uint64_t &LowPC, uint64_t &HighPC,
445                                uint64_t &SectionIndex) const {
446   auto F = find(DW_AT_low_pc);
447   auto LowPcAddr = toSectionedAddress(F);
448   if (!LowPcAddr)
449     return false;
450   if (auto HighPcAddr = getHighPC(LowPcAddr->Address)) {
451     LowPC = LowPcAddr->Address;
452     HighPC = *HighPcAddr;
453     SectionIndex = LowPcAddr->SectionIndex;
454     return true;
455   }
456   return false;
457 }
458 
459 Expected<DWARFAddressRangesVector> DWARFDie::getAddressRanges() const {
460   if (isNULL())
461     return DWARFAddressRangesVector();
462   // Single range specified by low/high PC.
463   uint64_t LowPC, HighPC, Index;
464   if (getLowAndHighPC(LowPC, HighPC, Index))
465     return DWARFAddressRangesVector{{LowPC, HighPC, Index}};
466 
467   Optional<DWARFFormValue> Value = find(DW_AT_ranges);
468   if (Value) {
469     if (Value->getForm() == DW_FORM_rnglistx)
470       return U->findRnglistFromIndex(*Value->getAsSectionOffset());
471     return U->findRnglistFromOffset(*Value->getAsSectionOffset());
472   }
473   return DWARFAddressRangesVector();
474 }
475 
476 void DWARFDie::collectChildrenAddressRanges(
477     DWARFAddressRangesVector &Ranges) const {
478   if (isNULL())
479     return;
480   if (isSubprogramDIE()) {
481     if (auto DIERangesOrError = getAddressRanges())
482       Ranges.insert(Ranges.end(), DIERangesOrError.get().begin(),
483                     DIERangesOrError.get().end());
484     else
485       llvm::consumeError(DIERangesOrError.takeError());
486   }
487 
488   for (auto Child : children())
489     Child.collectChildrenAddressRanges(Ranges);
490 }
491 
492 bool DWARFDie::addressRangeContainsAddress(const uint64_t Address) const {
493   auto RangesOrError = getAddressRanges();
494   if (!RangesOrError) {
495     llvm::consumeError(RangesOrError.takeError());
496     return false;
497   }
498 
499   for (const auto &R : RangesOrError.get())
500     if (R.LowPC <= Address && Address < R.HighPC)
501       return true;
502   return false;
503 }
504 
505 Expected<DWARFLocationExpressionsVector>
506 DWARFDie::getLocations(dwarf::Attribute Attr) const {
507   Optional<DWARFFormValue> Location = find(Attr);
508   if (!Location)
509     return createStringError(inconvertibleErrorCode(), "No %s",
510                              dwarf::AttributeString(Attr).data());
511 
512   if (Optional<uint64_t> Off = Location->getAsSectionOffset()) {
513     uint64_t Offset = *Off;
514 
515     if (Location->getForm() == DW_FORM_loclistx) {
516       if (auto LoclistOffset = U->getLoclistOffset(Offset))
517         Offset = *LoclistOffset;
518       else
519         return createStringError(inconvertibleErrorCode(),
520                                  "Loclist table not found");
521     }
522     return U->findLoclistFromOffset(Offset);
523   }
524 
525   if (Optional<ArrayRef<uint8_t>> Expr = Location->getAsBlock()) {
526     return DWARFLocationExpressionsVector{
527         DWARFLocationExpression{None, to_vector<4>(*Expr)}};
528   }
529 
530   return createStringError(
531       inconvertibleErrorCode(), "Unsupported %s encoding: %s",
532       dwarf::AttributeString(Attr).data(),
533       dwarf::FormEncodingString(Location->getForm()).data());
534 }
535 
536 const char *DWARFDie::getSubroutineName(DINameKind Kind) const {
537   if (!isSubroutineDIE())
538     return nullptr;
539   return getName(Kind);
540 }
541 
542 const char *DWARFDie::getName(DINameKind Kind) const {
543   if (!isValid() || Kind == DINameKind::None)
544     return nullptr;
545   // Try to get mangled name only if it was asked for.
546   if (Kind == DINameKind::LinkageName) {
547     if (auto Name = getLinkageName())
548       return Name;
549   }
550   return getShortName();
551 }
552 
553 const char *DWARFDie::getShortName() const {
554   if (!isValid())
555     return nullptr;
556 
557   return dwarf::toString(findRecursively(dwarf::DW_AT_name), nullptr);
558 }
559 
560 const char *DWARFDie::getLinkageName() const {
561   if (!isValid())
562     return nullptr;
563 
564   return dwarf::toString(findRecursively({dwarf::DW_AT_MIPS_linkage_name,
565                                           dwarf::DW_AT_linkage_name}),
566                          nullptr);
567 }
568 
569 uint64_t DWARFDie::getDeclLine() const {
570   return toUnsigned(findRecursively(DW_AT_decl_line), 0);
571 }
572 
573 std::string
574 DWARFDie::getDeclFile(DILineInfoSpecifier::FileLineInfoKind Kind) const {
575   std::string FileName;
576   if (auto DeclFile = toUnsigned(findRecursively(DW_AT_decl_file))) {
577     if (const auto *LT = U->getContext().getLineTableForUnit(U)) {
578       LT->getFileNameByIndex(*DeclFile, U->getCompilationDir(), Kind, FileName);
579     }
580   }
581   return FileName;
582 }
583 
584 void DWARFDie::getCallerFrame(uint32_t &CallFile, uint32_t &CallLine,
585                               uint32_t &CallColumn,
586                               uint32_t &CallDiscriminator) const {
587   CallFile = toUnsigned(find(DW_AT_call_file), 0);
588   CallLine = toUnsigned(find(DW_AT_call_line), 0);
589   CallColumn = toUnsigned(find(DW_AT_call_column), 0);
590   CallDiscriminator = toUnsigned(find(DW_AT_GNU_discriminator), 0);
591 }
592 
593 /// Helper to dump a DIE with all of its parents, but no siblings.
594 static unsigned dumpParentChain(DWARFDie Die, raw_ostream &OS, unsigned Indent,
595                                 DIDumpOptions DumpOpts, unsigned Depth = 0) {
596   if (!Die)
597     return Indent;
598   if (DumpOpts.ParentRecurseDepth > 0 && Depth >= DumpOpts.ParentRecurseDepth)
599     return Indent;
600   Indent = dumpParentChain(Die.getParent(), OS, Indent, DumpOpts, Depth + 1);
601   Die.dump(OS, Indent, DumpOpts);
602   return Indent + 2;
603 }
604 
605 void DWARFDie::dump(raw_ostream &OS, unsigned Indent,
606                     DIDumpOptions DumpOpts) const {
607   if (!isValid())
608     return;
609   DWARFDataExtractor debug_info_data = U->getDebugInfoExtractor();
610   const uint64_t Offset = getOffset();
611   uint64_t offset = Offset;
612   if (DumpOpts.ShowParents) {
613     DIDumpOptions ParentDumpOpts = DumpOpts;
614     ParentDumpOpts.ShowParents = false;
615     ParentDumpOpts.ShowChildren = false;
616     Indent = dumpParentChain(getParent(), OS, Indent, ParentDumpOpts);
617   }
618 
619   if (debug_info_data.isValidOffset(offset)) {
620     uint32_t abbrCode = debug_info_data.getULEB128(&offset);
621     if (DumpOpts.ShowAddresses)
622       WithColor(OS, HighlightColor::Address).get()
623           << format("\n0x%8.8" PRIx64 ": ", Offset);
624 
625     if (abbrCode) {
626       auto AbbrevDecl = getAbbreviationDeclarationPtr();
627       if (AbbrevDecl) {
628         WithColor(OS, HighlightColor::Tag).get().indent(Indent)
629             << formatv("{0}", getTag());
630         if (DumpOpts.Verbose)
631           OS << format(" [%u] %c", abbrCode,
632                        AbbrevDecl->hasChildren() ? '*' : ' ');
633         OS << '\n';
634 
635         // Dump all data in the DIE for the attributes.
636         for (const auto &AttrSpec : AbbrevDecl->attributes()) {
637           if (AttrSpec.Form == DW_FORM_implicit_const) {
638             // We are dumping .debug_info section ,
639             // implicit_const attribute values are not really stored here,
640             // but in .debug_abbrev section. So we just skip such attrs.
641             continue;
642           }
643           dumpAttribute(OS, *this, &offset, AttrSpec.Attr, AttrSpec.Form,
644                         Indent, DumpOpts);
645         }
646 
647         DWARFDie child = getFirstChild();
648         if (DumpOpts.ShowChildren && DumpOpts.ChildRecurseDepth > 0 && child) {
649           DumpOpts.ChildRecurseDepth--;
650           DIDumpOptions ChildDumpOpts = DumpOpts;
651           ChildDumpOpts.ShowParents = false;
652           while (child) {
653             child.dump(OS, Indent + 2, ChildDumpOpts);
654             child = child.getSibling();
655           }
656         }
657       } else {
658         OS << "Abbreviation code not found in 'debug_abbrev' class for code: "
659            << abbrCode << '\n';
660       }
661     } else {
662       OS.indent(Indent) << "NULL\n";
663     }
664   }
665 }
666 
667 LLVM_DUMP_METHOD void DWARFDie::dump() const { dump(llvm::errs(), 0); }
668 
669 DWARFDie DWARFDie::getParent() const {
670   if (isValid())
671     return U->getParent(Die);
672   return DWARFDie();
673 }
674 
675 DWARFDie DWARFDie::getSibling() const {
676   if (isValid())
677     return U->getSibling(Die);
678   return DWARFDie();
679 }
680 
681 DWARFDie DWARFDie::getPreviousSibling() const {
682   if (isValid())
683     return U->getPreviousSibling(Die);
684   return DWARFDie();
685 }
686 
687 DWARFDie DWARFDie::getFirstChild() const {
688   if (isValid())
689     return U->getFirstChild(Die);
690   return DWARFDie();
691 }
692 
693 DWARFDie DWARFDie::getLastChild() const {
694   if (isValid())
695     return U->getLastChild(Die);
696   return DWARFDie();
697 }
698 
699 iterator_range<DWARFDie::attribute_iterator> DWARFDie::attributes() const {
700   return make_range(attribute_iterator(*this, false),
701                     attribute_iterator(*this, true));
702 }
703 
704 DWARFDie::attribute_iterator::attribute_iterator(DWARFDie D, bool End)
705     : Die(D), Index(0) {
706   auto AbbrDecl = Die.getAbbreviationDeclarationPtr();
707   assert(AbbrDecl && "Must have abbreviation declaration");
708   if (End) {
709     // This is the end iterator so we set the index to the attribute count.
710     Index = AbbrDecl->getNumAttributes();
711   } else {
712     // This is the begin iterator so we extract the value for this->Index.
713     AttrValue.Offset = D.getOffset() + AbbrDecl->getCodeByteSize();
714     updateForIndex(*AbbrDecl, 0);
715   }
716 }
717 
718 void DWARFDie::attribute_iterator::updateForIndex(
719     const DWARFAbbreviationDeclaration &AbbrDecl, uint32_t I) {
720   Index = I;
721   // AbbrDecl must be valid before calling this function.
722   auto NumAttrs = AbbrDecl.getNumAttributes();
723   if (Index < NumAttrs) {
724     AttrValue.Attr = AbbrDecl.getAttrByIndex(Index);
725     // Add the previous byte size of any previous attribute value.
726     AttrValue.Offset += AttrValue.ByteSize;
727     uint64_t ParseOffset = AttrValue.Offset;
728     auto U = Die.getDwarfUnit();
729     assert(U && "Die must have valid DWARF unit");
730     AttrValue.Value = DWARFFormValue::createFromUnit(
731         AbbrDecl.getFormByIndex(Index), U, &ParseOffset);
732     AttrValue.ByteSize = ParseOffset - AttrValue.Offset;
733   } else {
734     assert(Index == NumAttrs && "Indexes should be [0, NumAttrs) only");
735     AttrValue = {};
736   }
737 }
738 
739 DWARFDie::attribute_iterator &DWARFDie::attribute_iterator::operator++() {
740   if (auto AbbrDecl = Die.getAbbreviationDeclarationPtr())
741     updateForIndex(*AbbrDecl, Index + 1);
742   return *this;
743 }
744 
745 bool DWARFAttribute::mayHaveLocationDescription(dwarf::Attribute Attr) {
746   switch (Attr) {
747   // From the DWARF v5 specification.
748   case DW_AT_location:
749   case DW_AT_byte_size:
750   case DW_AT_bit_size:
751   case DW_AT_string_length:
752   case DW_AT_lower_bound:
753   case DW_AT_return_addr:
754   case DW_AT_bit_stride:
755   case DW_AT_upper_bound:
756   case DW_AT_count:
757   case DW_AT_data_member_location:
758   case DW_AT_frame_base:
759   case DW_AT_segment:
760   case DW_AT_static_link:
761   case DW_AT_use_location:
762   case DW_AT_vtable_elem_location:
763   case DW_AT_allocated:
764   case DW_AT_associated:
765   case DW_AT_byte_stride:
766   case DW_AT_rank:
767   case DW_AT_call_value:
768   case DW_AT_call_origin:
769   case DW_AT_call_target:
770   case DW_AT_call_target_clobbered:
771   case DW_AT_call_data_location:
772   case DW_AT_call_data_value:
773   // Extensions.
774   case DW_AT_GNU_call_site_value:
775   case DW_AT_GNU_call_site_target:
776     return true;
777   default:
778     return false;
779   }
780 }
781