xref: /freebsd/contrib/llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp (revision 13ec1e3155c7e9bf037b12af186351b7fa9b9450) 
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 dumpLocationList(raw_ostream &OS, const DWARFFormValue &FormValue,
73                              DWARFUnit *U, unsigned Indent,
74                              DIDumpOptions DumpOpts) {
75   assert(FormValue.isFormClass(DWARFFormValue::FC_SectionOffset) &&
76          "bad FORM for location list");
77   DWARFContext &Ctx = U->getContext();
78   const MCRegisterInfo *MRI = Ctx.getRegisterInfo();
79   uint64_t Offset = *FormValue.getAsSectionOffset();
80 
81   if (FormValue.getForm() == DW_FORM_loclistx) {
82     FormValue.dump(OS, DumpOpts);
83 
84     if (auto LoclistOffset = U->getLoclistOffset(Offset))
85       Offset = *LoclistOffset;
86     else
87       return;
88   }
89   U->getLocationTable().dumpLocationList(&Offset, OS, U->getBaseAddress(), MRI,
90                                          Ctx.getDWARFObj(), U, DumpOpts,
91                                          Indent);
92   return;
93 }
94 
95 static void dumpLocationExpr(raw_ostream &OS, const DWARFFormValue &FormValue,
96                              DWARFUnit *U, unsigned Indent,
97                              DIDumpOptions DumpOpts) {
98   assert((FormValue.isFormClass(DWARFFormValue::FC_Block) ||
99           FormValue.isFormClass(DWARFFormValue::FC_Exprloc)) &&
100          "bad FORM for location expression");
101   DWARFContext &Ctx = U->getContext();
102   const MCRegisterInfo *MRI = Ctx.getRegisterInfo();
103   ArrayRef<uint8_t> Expr = *FormValue.getAsBlock();
104   DataExtractor Data(StringRef((const char *)Expr.data(), Expr.size()),
105                      Ctx.isLittleEndian(), 0);
106   DWARFExpression(Data, U->getAddressByteSize(), U->getFormParams().Format)
107       .print(OS, DumpOpts, MRI, U);
108   return;
109 }
110 
111 /// Dump the name encoded in the type tag.
112 static void dumpTypeTagName(raw_ostream &OS, dwarf::Tag T) {
113   StringRef TagStr = TagString(T);
114   if (!TagStr.startswith("DW_TAG_") || !TagStr.endswith("_type"))
115     return;
116   OS << TagStr.substr(7, TagStr.size() - 12) << " ";
117 }
118 
119 static void dumpArrayType(raw_ostream &OS, const DWARFDie &D) {
120   for (const DWARFDie &C : D.children())
121     if (C.getTag() == DW_TAG_subrange_type) {
122       Optional<uint64_t> LB;
123       Optional<uint64_t> Count;
124       Optional<uint64_t> UB;
125       Optional<unsigned> DefaultLB;
126       if (Optional<DWARFFormValue> L = C.find(DW_AT_lower_bound))
127         LB = L->getAsUnsignedConstant();
128       if (Optional<DWARFFormValue> CountV = C.find(DW_AT_count))
129         Count = CountV->getAsUnsignedConstant();
130       if (Optional<DWARFFormValue> UpperV = C.find(DW_AT_upper_bound))
131         UB = UpperV->getAsUnsignedConstant();
132       if (Optional<DWARFFormValue> LV =
133               D.getDwarfUnit()->getUnitDIE().find(DW_AT_language))
134         if (Optional<uint64_t> LC = LV->getAsUnsignedConstant())
135           if ((DefaultLB =
136                    LanguageLowerBound(static_cast<dwarf::SourceLanguage>(*LC))))
137             if (LB && *LB == *DefaultLB)
138               LB = None;
139       if (!LB && !Count && !UB)
140         OS << "[]";
141       else if (!LB && (Count || UB) && DefaultLB)
142         OS << '[' << (Count ? *Count : *UB - *DefaultLB + 1) << ']';
143       else {
144         OS << "[[";
145         if (LB)
146           OS << *LB;
147         else
148           OS << '?';
149         OS << ", ";
150         if (Count)
151           if (LB)
152             OS << *LB + *Count;
153           else
154             OS << "? + " << *Count;
155         else if (UB)
156           OS << *UB + 1;
157         else
158           OS << '?';
159         OS << ")]";
160       }
161     }
162 }
163 
164 /// Recursively dump the DIE type name when applicable.
165 static void dumpTypeName(raw_ostream &OS, const DWARFDie &D) {
166   if (!D.isValid())
167     return;
168 
169   if (const char *Name = D.getName(DINameKind::LinkageName)) {
170     OS << Name;
171     return;
172   }
173 
174   // FIXME: We should have pretty printers per language. Currently we print
175   // everything as if it was C++ and fall back to the TAG type name.
176   const dwarf::Tag T = D.getTag();
177   switch (T) {
178   case DW_TAG_array_type:
179   case DW_TAG_pointer_type:
180   case DW_TAG_ptr_to_member_type:
181   case DW_TAG_reference_type:
182   case DW_TAG_rvalue_reference_type:
183   case DW_TAG_subroutine_type:
184     break;
185   default:
186     dumpTypeTagName(OS, T);
187   }
188 
189   // Follow the DW_AT_type if possible.
190   DWARFDie TypeDie = D.getAttributeValueAsReferencedDie(DW_AT_type);
191   dumpTypeName(OS, TypeDie);
192 
193   switch (T) {
194   case DW_TAG_subroutine_type: {
195     if (!TypeDie)
196       OS << "void";
197     OS << '(';
198     bool First = true;
199     for (const DWARFDie &C : D.children()) {
200       if (C.getTag() == DW_TAG_formal_parameter) {
201         if (!First)
202           OS << ", ";
203         First = false;
204         dumpTypeName(OS, C.getAttributeValueAsReferencedDie(DW_AT_type));
205       }
206     }
207     OS << ')';
208     break;
209   }
210   case DW_TAG_array_type: {
211     dumpArrayType(OS, D);
212     break;
213   }
214   case DW_TAG_pointer_type:
215     OS << '*';
216     break;
217   case DW_TAG_ptr_to_member_type:
218     if (DWARFDie Cont =
219             D.getAttributeValueAsReferencedDie(DW_AT_containing_type)) {
220       dumpTypeName(OS << ' ', Cont);
221       OS << "::";
222     }
223     OS << '*';
224     break;
225   case DW_TAG_reference_type:
226     OS << '&';
227     break;
228   case DW_TAG_rvalue_reference_type:
229     OS << "&&";
230     break;
231   default:
232     break;
233   }
234 }
235 
236 static void dumpAttribute(raw_ostream &OS, const DWARFDie &Die,
237                           const DWARFAttribute &AttrValue, unsigned Indent,
238                           DIDumpOptions DumpOpts) {
239   if (!Die.isValid())
240     return;
241   const char BaseIndent[] = "            ";
242   OS << BaseIndent;
243   OS.indent(Indent + 2);
244   dwarf::Attribute Attr = AttrValue.Attr;
245   WithColor(OS, HighlightColor::Attribute) << formatv("{0}", Attr);
246 
247   dwarf::Form Form = AttrValue.Value.getForm();
248   if (DumpOpts.Verbose || DumpOpts.ShowForm)
249     OS << formatv(" [{0}]", Form);
250 
251   DWARFUnit *U = Die.getDwarfUnit();
252   const DWARFFormValue &FormValue = AttrValue.Value;
253 
254   OS << "\t(";
255 
256   StringRef Name;
257   std::string File;
258   auto Color = HighlightColor::Enumerator;
259   if (Attr == DW_AT_decl_file || Attr == DW_AT_call_file) {
260     Color = HighlightColor::String;
261     if (const auto *LT = U->getContext().getLineTableForUnit(U))
262       if (LT->getFileNameByIndex(
263               FormValue.getAsUnsignedConstant().getValue(),
264               U->getCompilationDir(),
265               DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, File)) {
266         File = '"' + File + '"';
267         Name = File;
268       }
269   } else if (Optional<uint64_t> Val = FormValue.getAsUnsignedConstant())
270     Name = AttributeValueString(Attr, *Val);
271 
272   if (!Name.empty())
273     WithColor(OS, Color) << Name;
274   else if (Attr == DW_AT_decl_line || Attr == DW_AT_call_line)
275     OS << *FormValue.getAsUnsignedConstant();
276   else if (Attr == DW_AT_low_pc &&
277            (FormValue.getAsAddress() ==
278             dwarf::computeTombstoneAddress(U->getAddressByteSize()))) {
279     if (DumpOpts.Verbose) {
280       FormValue.dump(OS, DumpOpts);
281       OS << " (";
282     }
283     OS << "dead code";
284     if (DumpOpts.Verbose)
285       OS << ')';
286   } else if (Attr == DW_AT_high_pc && !DumpOpts.ShowForm && !DumpOpts.Verbose &&
287              FormValue.getAsUnsignedConstant()) {
288     if (DumpOpts.ShowAddresses) {
289       // Print the actual address rather than the offset.
290       uint64_t LowPC, HighPC, Index;
291       if (Die.getLowAndHighPC(LowPC, HighPC, Index))
292         DWARFFormValue::dumpAddress(OS, U->getAddressByteSize(), HighPC);
293       else
294         FormValue.dump(OS, DumpOpts);
295     }
296   } else if (DWARFAttribute::mayHaveLocationList(Attr) &&
297              FormValue.isFormClass(DWARFFormValue::FC_SectionOffset))
298     dumpLocationList(OS, FormValue, U, sizeof(BaseIndent) + Indent + 4,
299                      DumpOpts);
300   else if (FormValue.isFormClass(DWARFFormValue::FC_Exprloc) ||
301            (DWARFAttribute::mayHaveLocationExpr(Attr) &&
302             FormValue.isFormClass(DWARFFormValue::FC_Block)))
303     dumpLocationExpr(OS, FormValue, U, sizeof(BaseIndent) + Indent + 4,
304                      DumpOpts);
305   else
306     FormValue.dump(OS, DumpOpts);
307 
308   std::string Space = DumpOpts.ShowAddresses ? " " : "";
309 
310   // We have dumped the attribute raw value. For some attributes
311   // having both the raw value and the pretty-printed value is
312   // interesting. These attributes are handled below.
313   if (Attr == DW_AT_specification || Attr == DW_AT_abstract_origin) {
314     if (const char *Name =
315             Die.getAttributeValueAsReferencedDie(FormValue).getName(
316                 DINameKind::LinkageName))
317       OS << Space << "\"" << Name << '\"';
318   } else if (Attr == DW_AT_type) {
319     OS << Space << "\"";
320     dumpTypeName(OS, Die.getAttributeValueAsReferencedDie(FormValue));
321     OS << '"';
322   } else if (Attr == DW_AT_APPLE_property_attribute) {
323     if (Optional<uint64_t> OptVal = FormValue.getAsUnsignedConstant())
324       dumpApplePropertyAttribute(OS, *OptVal);
325   } else if (Attr == DW_AT_ranges) {
326     const DWARFObject &Obj = Die.getDwarfUnit()->getContext().getDWARFObj();
327     // For DW_FORM_rnglistx we need to dump the offset separately, since
328     // we have only dumped the index so far.
329     if (FormValue.getForm() == DW_FORM_rnglistx)
330       if (auto RangeListOffset =
331               U->getRnglistOffset(*FormValue.getAsSectionOffset())) {
332         DWARFFormValue FV = DWARFFormValue::createFromUValue(
333             dwarf::DW_FORM_sec_offset, *RangeListOffset);
334         FV.dump(OS, DumpOpts);
335       }
336     if (auto RangesOrError = Die.getAddressRanges())
337       dumpRanges(Obj, OS, RangesOrError.get(), U->getAddressByteSize(),
338                  sizeof(BaseIndent) + Indent + 4, DumpOpts);
339     else
340       DumpOpts.RecoverableErrorHandler(createStringError(
341           errc::invalid_argument, "decoding address ranges: %s",
342           toString(RangesOrError.takeError()).c_str()));
343   }
344 
345   OS << ")\n";
346 }
347 
348 bool DWARFDie::isSubprogramDIE() const { return getTag() == DW_TAG_subprogram; }
349 
350 bool DWARFDie::isSubroutineDIE() const {
351   auto Tag = getTag();
352   return Tag == DW_TAG_subprogram || Tag == DW_TAG_inlined_subroutine;
353 }
354 
355 Optional<DWARFFormValue> DWARFDie::find(dwarf::Attribute Attr) const {
356   if (!isValid())
357     return None;
358   auto AbbrevDecl = getAbbreviationDeclarationPtr();
359   if (AbbrevDecl)
360     return AbbrevDecl->getAttributeValue(getOffset(), Attr, *U);
361   return None;
362 }
363 
364 Optional<DWARFFormValue>
365 DWARFDie::find(ArrayRef<dwarf::Attribute> Attrs) const {
366   if (!isValid())
367     return None;
368   auto AbbrevDecl = getAbbreviationDeclarationPtr();
369   if (AbbrevDecl) {
370     for (auto Attr : Attrs) {
371       if (auto Value = AbbrevDecl->getAttributeValue(getOffset(), Attr, *U))
372         return Value;
373     }
374   }
375   return None;
376 }
377 
378 Optional<DWARFFormValue>
379 DWARFDie::findRecursively(ArrayRef<dwarf::Attribute> Attrs) const {
380   SmallVector<DWARFDie, 3> Worklist;
381   Worklist.push_back(*this);
382 
383   // Keep track if DIEs already seen to prevent infinite recursion.
384   // Empirically we rarely see a depth of more than 3 when dealing with valid
385   // DWARF. This corresponds to following the DW_AT_abstract_origin and
386   // DW_AT_specification just once.
387   SmallSet<DWARFDie, 3> Seen;
388   Seen.insert(*this);
389 
390   while (!Worklist.empty()) {
391     DWARFDie Die = Worklist.pop_back_val();
392 
393     if (!Die.isValid())
394       continue;
395 
396     if (auto Value = Die.find(Attrs))
397       return Value;
398 
399     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_abstract_origin))
400       if (Seen.insert(D).second)
401         Worklist.push_back(D);
402 
403     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_specification))
404       if (Seen.insert(D).second)
405         Worklist.push_back(D);
406   }
407 
408   return None;
409 }
410 
411 DWARFDie
412 DWARFDie::getAttributeValueAsReferencedDie(dwarf::Attribute Attr) const {
413   if (Optional<DWARFFormValue> F = find(Attr))
414     return getAttributeValueAsReferencedDie(*F);
415   return DWARFDie();
416 }
417 
418 DWARFDie
419 DWARFDie::getAttributeValueAsReferencedDie(const DWARFFormValue &V) const {
420   if (auto SpecRef = V.getAsRelativeReference()) {
421     if (SpecRef->Unit)
422       return SpecRef->Unit->getDIEForOffset(SpecRef->Unit->getOffset() + SpecRef->Offset);
423     if (auto SpecUnit = U->getUnitVector().getUnitForOffset(SpecRef->Offset))
424       return SpecUnit->getDIEForOffset(SpecRef->Offset);
425   }
426   return DWARFDie();
427 }
428 
429 Optional<uint64_t> DWARFDie::getRangesBaseAttribute() const {
430   return toSectionOffset(find({DW_AT_rnglists_base, DW_AT_GNU_ranges_base}));
431 }
432 
433 Optional<uint64_t> DWARFDie::getLocBaseAttribute() const {
434   return toSectionOffset(find(DW_AT_loclists_base));
435 }
436 
437 Optional<uint64_t> DWARFDie::getHighPC(uint64_t LowPC) const {
438   uint64_t Tombstone = dwarf::computeTombstoneAddress(U->getAddressByteSize());
439   if (LowPC == Tombstone)
440     return None;
441   if (auto FormValue = find(DW_AT_high_pc)) {
442     if (auto Address = FormValue->getAsAddress()) {
443       // High PC is an address.
444       return Address;
445     }
446     if (auto Offset = FormValue->getAsUnsignedConstant()) {
447       // High PC is an offset from LowPC.
448       return LowPC + *Offset;
449     }
450   }
451   return None;
452 }
453 
454 bool DWARFDie::getLowAndHighPC(uint64_t &LowPC, uint64_t &HighPC,
455                                uint64_t &SectionIndex) const {
456   auto F = find(DW_AT_low_pc);
457   auto LowPcAddr = toSectionedAddress(F);
458   if (!LowPcAddr)
459     return false;
460   if (auto HighPcAddr = getHighPC(LowPcAddr->Address)) {
461     LowPC = LowPcAddr->Address;
462     HighPC = *HighPcAddr;
463     SectionIndex = LowPcAddr->SectionIndex;
464     return true;
465   }
466   return false;
467 }
468 
469 Expected<DWARFAddressRangesVector> DWARFDie::getAddressRanges() const {
470   if (isNULL())
471     return DWARFAddressRangesVector();
472   // Single range specified by low/high PC.
473   uint64_t LowPC, HighPC, Index;
474   if (getLowAndHighPC(LowPC, HighPC, Index))
475     return DWARFAddressRangesVector{{LowPC, HighPC, Index}};
476 
477   Optional<DWARFFormValue> Value = find(DW_AT_ranges);
478   if (Value) {
479     if (Value->getForm() == DW_FORM_rnglistx)
480       return U->findRnglistFromIndex(*Value->getAsSectionOffset());
481     return U->findRnglistFromOffset(*Value->getAsSectionOffset());
482   }
483   return DWARFAddressRangesVector();
484 }
485 
486 void DWARFDie::collectChildrenAddressRanges(
487     DWARFAddressRangesVector &Ranges) const {
488   if (isNULL())
489     return;
490   if (isSubprogramDIE()) {
491     if (auto DIERangesOrError = getAddressRanges())
492       llvm::append_range(Ranges, DIERangesOrError.get());
493     else
494       llvm::consumeError(DIERangesOrError.takeError());
495   }
496 
497   for (auto Child : children())
498     Child.collectChildrenAddressRanges(Ranges);
499 }
500 
501 bool DWARFDie::addressRangeContainsAddress(const uint64_t Address) const {
502   auto RangesOrError = getAddressRanges();
503   if (!RangesOrError) {
504     llvm::consumeError(RangesOrError.takeError());
505     return false;
506   }
507 
508   for (const auto &R : RangesOrError.get())
509     if (R.LowPC <= Address && Address < R.HighPC)
510       return true;
511   return false;
512 }
513 
514 Expected<DWARFLocationExpressionsVector>
515 DWARFDie::getLocations(dwarf::Attribute Attr) const {
516   Optional<DWARFFormValue> Location = find(Attr);
517   if (!Location)
518     return createStringError(inconvertibleErrorCode(), "No %s",
519                              dwarf::AttributeString(Attr).data());
520 
521   if (Optional<uint64_t> Off = Location->getAsSectionOffset()) {
522     uint64_t Offset = *Off;
523 
524     if (Location->getForm() == DW_FORM_loclistx) {
525       if (auto LoclistOffset = U->getLoclistOffset(Offset))
526         Offset = *LoclistOffset;
527       else
528         return createStringError(inconvertibleErrorCode(),
529                                  "Loclist table not found");
530     }
531     return U->findLoclistFromOffset(Offset);
532   }
533 
534   if (Optional<ArrayRef<uint8_t>> Expr = Location->getAsBlock()) {
535     return DWARFLocationExpressionsVector{
536         DWARFLocationExpression{None, to_vector<4>(*Expr)}};
537   }
538 
539   return createStringError(
540       inconvertibleErrorCode(), "Unsupported %s encoding: %s",
541       dwarf::AttributeString(Attr).data(),
542       dwarf::FormEncodingString(Location->getForm()).data());
543 }
544 
545 const char *DWARFDie::getSubroutineName(DINameKind Kind) const {
546   if (!isSubroutineDIE())
547     return nullptr;
548   return getName(Kind);
549 }
550 
551 const char *DWARFDie::getName(DINameKind Kind) const {
552   if (!isValid() || Kind == DINameKind::None)
553     return nullptr;
554   // Try to get mangled name only if it was asked for.
555   if (Kind == DINameKind::LinkageName) {
556     if (auto Name = getLinkageName())
557       return Name;
558   }
559   return getShortName();
560 }
561 
562 const char *DWARFDie::getShortName() const {
563   if (!isValid())
564     return nullptr;
565 
566   return dwarf::toString(findRecursively(dwarf::DW_AT_name), nullptr);
567 }
568 
569 const char *DWARFDie::getLinkageName() const {
570   if (!isValid())
571     return nullptr;
572 
573   return dwarf::toString(findRecursively({dwarf::DW_AT_MIPS_linkage_name,
574                                           dwarf::DW_AT_linkage_name}),
575                          nullptr);
576 }
577 
578 uint64_t DWARFDie::getDeclLine() const {
579   return toUnsigned(findRecursively(DW_AT_decl_line), 0);
580 }
581 
582 std::string
583 DWARFDie::getDeclFile(DILineInfoSpecifier::FileLineInfoKind Kind) const {
584   auto D = getAttributeValueAsReferencedDie(DW_AT_abstract_origin);
585   if (!D)
586     D = *this;
587   std::string FileName;
588   if (auto DeclFile = toUnsigned(D.find(DW_AT_decl_file))) {
589     if (const auto *LineTable =
590             getDwarfUnit()->getContext().getLineTableForUnit(
591                 D.getDwarfUnit()->getLinkedUnit()))
592       LineTable->getFileNameByIndex(
593           *DeclFile, D.getDwarfUnit()->getCompilationDir(), Kind, FileName);
594   }
595   return FileName;
596 }
597 
598 void DWARFDie::getCallerFrame(uint32_t &CallFile, uint32_t &CallLine,
599                               uint32_t &CallColumn,
600                               uint32_t &CallDiscriminator) const {
601   CallFile = toUnsigned(find(DW_AT_call_file), 0);
602   CallLine = toUnsigned(find(DW_AT_call_line), 0);
603   CallColumn = toUnsigned(find(DW_AT_call_column), 0);
604   CallDiscriminator = toUnsigned(find(DW_AT_GNU_discriminator), 0);
605 }
606 
607 /// Helper to dump a DIE with all of its parents, but no siblings.
608 static unsigned dumpParentChain(DWARFDie Die, raw_ostream &OS, unsigned Indent,
609                                 DIDumpOptions DumpOpts, unsigned Depth = 0) {
610   if (!Die)
611     return Indent;
612   if (DumpOpts.ParentRecurseDepth > 0 && Depth >= DumpOpts.ParentRecurseDepth)
613     return Indent;
614   Indent = dumpParentChain(Die.getParent(), OS, Indent, DumpOpts, Depth + 1);
615   Die.dump(OS, Indent, DumpOpts);
616   return Indent + 2;
617 }
618 
619 void DWARFDie::dump(raw_ostream &OS, unsigned Indent,
620                     DIDumpOptions DumpOpts) const {
621   if (!isValid())
622     return;
623   DWARFDataExtractor debug_info_data = U->getDebugInfoExtractor();
624   const uint64_t Offset = getOffset();
625   uint64_t offset = Offset;
626   if (DumpOpts.ShowParents) {
627     DIDumpOptions ParentDumpOpts = DumpOpts;
628     ParentDumpOpts.ShowParents = false;
629     ParentDumpOpts.ShowChildren = false;
630     Indent = dumpParentChain(getParent(), OS, Indent, ParentDumpOpts);
631   }
632 
633   if (debug_info_data.isValidOffset(offset)) {
634     uint32_t abbrCode = debug_info_data.getULEB128(&offset);
635     if (DumpOpts.ShowAddresses)
636       WithColor(OS, HighlightColor::Address).get()
637           << format("\n0x%8.8" PRIx64 ": ", Offset);
638 
639     if (abbrCode) {
640       auto AbbrevDecl = getAbbreviationDeclarationPtr();
641       if (AbbrevDecl) {
642         WithColor(OS, HighlightColor::Tag).get().indent(Indent)
643             << formatv("{0}", getTag());
644         if (DumpOpts.Verbose)
645           OS << format(" [%u] %c", abbrCode,
646                        AbbrevDecl->hasChildren() ? '*' : ' ');
647         OS << '\n';
648 
649         // Dump all data in the DIE for the attributes.
650         for (const DWARFAttribute &AttrValue : attributes())
651           dumpAttribute(OS, *this, AttrValue, Indent, DumpOpts);
652 
653         if (DumpOpts.ShowChildren && DumpOpts.ChildRecurseDepth > 0) {
654           DWARFDie Child = getFirstChild();
655           DumpOpts.ChildRecurseDepth--;
656           DIDumpOptions ChildDumpOpts = DumpOpts;
657           ChildDumpOpts.ShowParents = false;
658           while (Child) {
659             Child.dump(OS, Indent + 2, ChildDumpOpts);
660             Child = Child.getSibling();
661           }
662         }
663       } else {
664         OS << "Abbreviation code not found in 'debug_abbrev' class for code: "
665            << abbrCode << '\n';
666       }
667     } else {
668       OS.indent(Indent) << "NULL\n";
669     }
670   }
671 }
672 
673 LLVM_DUMP_METHOD void DWARFDie::dump() const { dump(llvm::errs(), 0); }
674 
675 DWARFDie DWARFDie::getParent() const {
676   if (isValid())
677     return U->getParent(Die);
678   return DWARFDie();
679 }
680 
681 DWARFDie DWARFDie::getSibling() const {
682   if (isValid())
683     return U->getSibling(Die);
684   return DWARFDie();
685 }
686 
687 DWARFDie DWARFDie::getPreviousSibling() const {
688   if (isValid())
689     return U->getPreviousSibling(Die);
690   return DWARFDie();
691 }
692 
693 DWARFDie DWARFDie::getFirstChild() const {
694   if (isValid())
695     return U->getFirstChild(Die);
696   return DWARFDie();
697 }
698 
699 DWARFDie DWARFDie::getLastChild() const {
700   if (isValid())
701     return U->getLastChild(Die);
702   return DWARFDie();
703 }
704 
705 iterator_range<DWARFDie::attribute_iterator> DWARFDie::attributes() const {
706   return make_range(attribute_iterator(*this, false),
707                     attribute_iterator(*this, true));
708 }
709 
710 DWARFDie::attribute_iterator::attribute_iterator(DWARFDie D, bool End)
711     : Die(D), Index(0) {
712   auto AbbrDecl = Die.getAbbreviationDeclarationPtr();
713   assert(AbbrDecl && "Must have abbreviation declaration");
714   if (End) {
715     // This is the end iterator so we set the index to the attribute count.
716     Index = AbbrDecl->getNumAttributes();
717   } else {
718     // This is the begin iterator so we extract the value for this->Index.
719     AttrValue.Offset = D.getOffset() + AbbrDecl->getCodeByteSize();
720     updateForIndex(*AbbrDecl, 0);
721   }
722 }
723 
724 void DWARFDie::attribute_iterator::updateForIndex(
725     const DWARFAbbreviationDeclaration &AbbrDecl, uint32_t I) {
726   Index = I;
727   // AbbrDecl must be valid before calling this function.
728   auto NumAttrs = AbbrDecl.getNumAttributes();
729   if (Index < NumAttrs) {
730     AttrValue.Attr = AbbrDecl.getAttrByIndex(Index);
731     // Add the previous byte size of any previous attribute value.
732     AttrValue.Offset += AttrValue.ByteSize;
733     uint64_t ParseOffset = AttrValue.Offset;
734     if (AbbrDecl.getAttrIsImplicitConstByIndex(Index))
735       AttrValue.Value = DWARFFormValue::createFromSValue(
736           AbbrDecl.getFormByIndex(Index),
737           AbbrDecl.getAttrImplicitConstValueByIndex(Index));
738     else {
739       auto U = Die.getDwarfUnit();
740       assert(U && "Die must have valid DWARF unit");
741       AttrValue.Value = DWARFFormValue::createFromUnit(
742           AbbrDecl.getFormByIndex(Index), U, &ParseOffset);
743     }
744     AttrValue.ByteSize = ParseOffset - AttrValue.Offset;
745   } else {
746     assert(Index == NumAttrs && "Indexes should be [0, NumAttrs) only");
747     AttrValue = {};
748   }
749 }
750 
751 DWARFDie::attribute_iterator &DWARFDie::attribute_iterator::operator++() {
752   if (auto AbbrDecl = Die.getAbbreviationDeclarationPtr())
753     updateForIndex(*AbbrDecl, Index + 1);
754   return *this;
755 }
756 
757 bool DWARFAttribute::mayHaveLocationList(dwarf::Attribute Attr) {
758   switch(Attr) {
759   case DW_AT_location:
760   case DW_AT_string_length:
761   case DW_AT_return_addr:
762   case DW_AT_data_member_location:
763   case DW_AT_frame_base:
764   case DW_AT_static_link:
765   case DW_AT_segment:
766   case DW_AT_use_location:
767   case DW_AT_vtable_elem_location:
768     return true;
769   default:
770     return false;
771   }
772 }
773 
774 bool DWARFAttribute::mayHaveLocationExpr(dwarf::Attribute Attr) {
775   switch (Attr) {
776   // From the DWARF v5 specification.
777   case DW_AT_location:
778   case DW_AT_byte_size:
779   case DW_AT_bit_offset:
780   case DW_AT_bit_size:
781   case DW_AT_string_length:
782   case DW_AT_lower_bound:
783   case DW_AT_return_addr:
784   case DW_AT_bit_stride:
785   case DW_AT_upper_bound:
786   case DW_AT_count:
787   case DW_AT_data_member_location:
788   case DW_AT_frame_base:
789   case DW_AT_segment:
790   case DW_AT_static_link:
791   case DW_AT_use_location:
792   case DW_AT_vtable_elem_location:
793   case DW_AT_allocated:
794   case DW_AT_associated:
795   case DW_AT_data_location:
796   case DW_AT_byte_stride:
797   case DW_AT_rank:
798   case DW_AT_call_value:
799   case DW_AT_call_origin:
800   case DW_AT_call_target:
801   case DW_AT_call_target_clobbered:
802   case DW_AT_call_data_location:
803   case DW_AT_call_data_value:
804   // Extensions.
805   case DW_AT_GNU_call_site_value:
806   case DW_AT_GNU_call_site_target:
807     return true;
808   default:
809     return false;
810   }
811 }
812