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 namespace {
112 
113 // FIXME: We should have pretty printers per language. Currently we print
114 // everything as if it was C++ and fall back to the TAG type name.
115 struct DWARFTypePrinter {
116   raw_ostream &OS;
117   bool Word = true;
118   bool EndedWithTemplate = false;
119 
120   DWARFTypePrinter(raw_ostream &OS) : OS(OS) {}
121 
122   /// Dump the name encoded in the type tag.
123   void appendTypeTagName(dwarf::Tag T) {
124     StringRef TagStr = TagString(T);
125     static constexpr StringRef Prefix = "DW_TAG_";
126     static constexpr StringRef Suffix = "_type";
127     if (!TagStr.startswith(Prefix) || !TagStr.endswith(Suffix))
128       return;
129     OS << TagStr.substr(Prefix.size(),
130                         TagStr.size() - (Prefix.size() + Suffix.size()))
131        << " ";
132   }
133 
134   void appendArrayType(const DWARFDie &D) {
135     for (const DWARFDie &C : D.children()) {
136       if (C.getTag() != DW_TAG_subrange_type)
137         continue;
138       Optional<uint64_t> LB;
139       Optional<uint64_t> Count;
140       Optional<uint64_t> UB;
141       Optional<unsigned> DefaultLB;
142       if (Optional<DWARFFormValue> L = C.find(DW_AT_lower_bound))
143         LB = L->getAsUnsignedConstant();
144       if (Optional<DWARFFormValue> CountV = C.find(DW_AT_count))
145         Count = CountV->getAsUnsignedConstant();
146       if (Optional<DWARFFormValue> UpperV = C.find(DW_AT_upper_bound))
147         UB = UpperV->getAsUnsignedConstant();
148       if (Optional<DWARFFormValue> LV =
149               D.getDwarfUnit()->getUnitDIE().find(DW_AT_language))
150         if (Optional<uint64_t> LC = LV->getAsUnsignedConstant())
151           if ((DefaultLB =
152                    LanguageLowerBound(static_cast<dwarf::SourceLanguage>(*LC))))
153             if (LB && *LB == *DefaultLB)
154               LB = None;
155       if (!LB && !Count && !UB)
156         OS << "[]";
157       else if (!LB && (Count || UB) && DefaultLB)
158         OS << '[' << (Count ? *Count : *UB - *DefaultLB + 1) << ']';
159       else {
160         OS << "[[";
161         if (LB)
162           OS << *LB;
163         else
164           OS << '?';
165         OS << ", ";
166         if (Count)
167           if (LB)
168             OS << *LB + *Count;
169           else
170             OS << "? + " << *Count;
171         else if (UB)
172           OS << *UB + 1;
173         else
174           OS << '?';
175         OS << ")]";
176       }
177     }
178   }
179 
180   DWARFDie skipQualifiers(DWARFDie D) {
181     while (D && (D.getTag() == DW_TAG_const_type ||
182                  D.getTag() == DW_TAG_volatile_type))
183       D = D.getAttributeValueAsReferencedDie(DW_AT_type);
184     return D;
185   }
186 
187   bool needsParens(DWARFDie D) {
188     D = skipQualifiers(D);
189     return D && (D.getTag() == DW_TAG_subroutine_type || D.getTag() == DW_TAG_array_type);
190   }
191 
192   void appendPointerLikeTypeBefore(DWARFDie D, DWARFDie Inner, StringRef Ptr) {
193     appendQualifiedNameBefore(Inner);
194     if (Word)
195       OS << ' ';
196     if (needsParens(Inner))
197       OS << '(';
198     OS << Ptr;
199     Word = false;
200   }
201 
202   DWARFDie appendUnqualifiedNameBefore(DWARFDie D) {
203     Word = true;
204     if (!D) {
205       OS << "void";
206       return DWARFDie();
207     }
208     DWARFDie Inner = D.getAttributeValueAsReferencedDie(DW_AT_type);
209     const dwarf::Tag T = D.getTag();
210     switch (T) {
211     case DW_TAG_pointer_type: {
212       appendPointerLikeTypeBefore(D, Inner, "*");
213       break;
214     }
215     case DW_TAG_subroutine_type: {
216       appendQualifiedNameBefore(Inner);
217       if (Word) {
218         OS << ' ';
219       }
220       Word = false;
221       break;
222     }
223     case DW_TAG_array_type: {
224       appendQualifiedNameBefore(Inner);
225       if (Word)
226         OS << ' ';
227       Word = false;
228       break;
229     }
230     case DW_TAG_reference_type:
231       appendPointerLikeTypeBefore(D, Inner, "&");
232       break;
233     case DW_TAG_rvalue_reference_type:
234       appendPointerLikeTypeBefore(D, Inner, "&&");
235       break;
236     case DW_TAG_ptr_to_member_type: {
237       appendQualifiedNameBefore(Inner);
238       if (needsParens(Inner))
239         OS << '(';
240       else if (Word)
241         OS << ' ';
242       if (DWARFDie Cont =
243               D.getAttributeValueAsReferencedDie(DW_AT_containing_type)) {
244         appendQualifiedName(Cont);
245         OS << "::";
246       }
247       OS << "*";
248       Word = false;
249       break;
250     }
251     case DW_TAG_const_type:
252     case DW_TAG_volatile_type:
253       appendConstVolatileQualifierBefore(D);
254       break;
255     case DW_TAG_namespace: {
256       if (const char *Name = dwarf::toString(D.find(DW_AT_name), nullptr))
257         OS << Name;
258       else
259         OS << "(anonymous namespace)";
260       break;
261     }
262     case DW_TAG_unspecified_type: {
263       StringRef TypeName = D.getShortName();
264       if (TypeName == "decltype(nullptr)")
265         TypeName = "std::nullptr_t";
266       Word = true;
267       OS << TypeName;
268       EndedWithTemplate = false;
269       break;
270     }
271     default:
272       const char *NamePtr = dwarf::toString(D.find(DW_AT_name), nullptr);
273       if (!NamePtr) {
274         appendTypeTagName(D.getTag());
275         break;
276       }
277       OS << NamePtr;
278       break;
279     }
280     return Inner;
281   }
282 
283   void appendUnqualifiedNameAfter(DWARFDie D, DWARFDie Inner,
284                                   bool SkipFirstParamIfArtificial = false) {
285     if (!D)
286       return;
287     switch (D.getTag()) {
288     case DW_TAG_subroutine_type: {
289       appendSubroutineNameAfter(D, Inner, SkipFirstParamIfArtificial, false,
290                                 false);
291       break;
292     }
293     case DW_TAG_array_type: {
294       appendArrayType(D);
295       break;
296     }
297     case DW_TAG_const_type:
298     case DW_TAG_volatile_type:
299       appendConstVolatileQualifierAfter(D);
300       break;
301     case DW_TAG_ptr_to_member_type:
302     case DW_TAG_reference_type:
303     case DW_TAG_rvalue_reference_type:
304     case DW_TAG_pointer_type: {
305       if (needsParens(Inner))
306         OS << ')';
307       appendUnqualifiedNameAfter(
308           Inner, Inner.getAttributeValueAsReferencedDie(DW_AT_type),
309           /*SkipFirstParamIfArtificial=*/D.getTag() ==
310               DW_TAG_ptr_to_member_type);
311       break;
312     }
313     default:
314       break;
315     }
316   }
317 
318   void appendQualifiedName(DWARFDie D) {
319     if (D)
320       appendScopes(D.getParent());
321     appendUnqualifiedName(D);
322   }
323   DWARFDie appendQualifiedNameBefore(DWARFDie D) {
324     if (D)
325       appendScopes(D.getParent());
326     return appendUnqualifiedNameBefore(D);
327   }
328   void decomposeConstVolatile(DWARFDie &N, DWARFDie &T, DWARFDie &C,
329                               DWARFDie &V) {
330     (N.getTag() == DW_TAG_const_type ? C : V) = N;
331     T = N.getAttributeValueAsReferencedDie(DW_AT_type);
332     if (T) {
333       auto Tag = T.getTag();
334       if (Tag == DW_TAG_const_type) {
335         C = T;
336         T = T.getAttributeValueAsReferencedDie(DW_AT_type);
337       } else if (Tag == DW_TAG_volatile_type) {
338         V = T;
339         T = T.getAttributeValueAsReferencedDie(DW_AT_type);
340       }
341     }
342   }
343   void appendConstVolatileQualifierAfter(DWARFDie N) {
344     DWARFDie C;
345     DWARFDie V;
346     DWARFDie T;
347     decomposeConstVolatile(N, T, C, V);
348     if (T && T.getTag() == DW_TAG_subroutine_type)
349       appendSubroutineNameAfter(T,
350                                 T.getAttributeValueAsReferencedDie(DW_AT_type),
351                                 false, C.isValid(), V.isValid());
352     else
353       appendUnqualifiedNameAfter(
354           T, T.getAttributeValueAsReferencedDie(DW_AT_type));
355   }
356   void appendConstVolatileQualifierBefore(DWARFDie N) {
357     DWARFDie C;
358     DWARFDie V;
359     DWARFDie T;
360     decomposeConstVolatile(N, T, C, V);
361     bool Subroutine = T && T.getTag() == DW_TAG_subroutine_type;
362     DWARFDie A = T;
363     while (A && A.getTag() == DW_TAG_array_type)
364       A = A.getAttributeValueAsReferencedDie(DW_AT_type);
365     bool Leading =
366         (!A || (A.getTag() != DW_TAG_pointer_type &&
367                 A.getTag() != llvm::dwarf::DW_TAG_ptr_to_member_type)) &&
368         !Subroutine;
369     if (Leading) {
370       if (C)
371         OS << "const ";
372       if (V)
373         OS << "volatile ";
374     }
375     appendQualifiedNameBefore(T);
376     if (!Leading && !Subroutine) {
377       Word = true;
378       if (C)
379         OS << "const";
380       if (V) {
381         if (C)
382           OS << ' ';
383         OS << "volatile";
384       }
385     }
386   }
387 
388   /// Recursively append the DIE type name when applicable.
389   void appendUnqualifiedName(const DWARFDie &D) {
390     // FIXME: We should have pretty printers per language. Currently we print
391     // everything as if it was C++ and fall back to the TAG type name.
392     DWARFDie Inner = appendUnqualifiedNameBefore(D);
393     appendUnqualifiedNameAfter(D, Inner);
394   }
395 
396   void appendSubroutineNameAfter(DWARFDie D, DWARFDie Inner,
397                                  bool SkipFirstParamIfArtificial, bool Const,
398                                  bool Volatile) {
399     DWARFDie FirstParamIfArtificial;
400     OS << '(';
401     EndedWithTemplate = false;
402     bool First = true;
403     bool RealFirst = true;
404     for (DWARFDie P : D) {
405       if (P.getTag() != DW_TAG_formal_parameter)
406         return;
407       DWARFDie T = P.getAttributeValueAsReferencedDie(DW_AT_type);
408       if (SkipFirstParamIfArtificial && RealFirst && P.find(DW_AT_artificial)) {
409         FirstParamIfArtificial = T;
410         RealFirst = false;
411         continue;
412       }
413       if (!First) {
414         OS << ", ";
415       }
416       First = false;
417       appendQualifiedName(T);
418     }
419     EndedWithTemplate = false;
420     OS << ')';
421     if (FirstParamIfArtificial) {
422       if (DWARFDie P = FirstParamIfArtificial) {
423         if (P.getTag() == DW_TAG_pointer_type) {
424           DWARFDie C;
425           DWARFDie V;
426           auto CVStep = [&](DWARFDie CV) {
427             if (DWARFDie U = CV.getAttributeValueAsReferencedDie(DW_AT_type)) {
428               if (U.getTag() == DW_TAG_const_type)
429                 return C = U;
430               if (U.getTag() == DW_TAG_volatile_type)
431                 return V = U;
432             }
433             return DWARFDie();
434           };
435           if (DWARFDie CV = CVStep(P)) {
436             CVStep(CV);
437           }
438           if (C)
439             OS << " const";
440           if (V)
441             OS << " volatile";
442         }
443       }
444     } else {
445       if (Const)
446         OS << " const";
447       if (Volatile)
448         OS << " volatile";
449     }
450     if (D.find(DW_AT_reference))
451       OS << " &";
452     if (D.find(DW_AT_rvalue_reference))
453       OS << " &&";
454     appendUnqualifiedNameAfter(
455         Inner, Inner.getAttributeValueAsReferencedDie(DW_AT_type));
456   }
457   void appendScopes(DWARFDie D) {
458     if (D.getTag() == DW_TAG_compile_unit)
459       return;
460     if (D.getTag() == DW_TAG_type_unit)
461       return;
462     if (D.getTag() == llvm::dwarf::DW_TAG_skeleton_unit)
463       return;
464     if (D.getTag() == DW_TAG_subprogram)
465       return;
466     if (DWARFDie P = D.getParent())
467       appendScopes(P);
468     appendUnqualifiedName(D);
469     OS << "::";
470   }
471 };
472 } // anonymous namespace
473 
474 static void dumpAttribute(raw_ostream &OS, const DWARFDie &Die,
475                           const DWARFAttribute &AttrValue, unsigned Indent,
476                           DIDumpOptions DumpOpts) {
477   if (!Die.isValid())
478     return;
479   const char BaseIndent[] = "            ";
480   OS << BaseIndent;
481   OS.indent(Indent + 2);
482   dwarf::Attribute Attr = AttrValue.Attr;
483   WithColor(OS, HighlightColor::Attribute) << formatv("{0}", Attr);
484 
485   dwarf::Form Form = AttrValue.Value.getForm();
486   if (DumpOpts.Verbose || DumpOpts.ShowForm)
487     OS << formatv(" [{0}]", Form);
488 
489   DWARFUnit *U = Die.getDwarfUnit();
490   const DWARFFormValue &FormValue = AttrValue.Value;
491 
492   OS << "\t(";
493 
494   StringRef Name;
495   std::string File;
496   auto Color = HighlightColor::Enumerator;
497   if (Attr == DW_AT_decl_file || Attr == DW_AT_call_file) {
498     Color = HighlightColor::String;
499     if (const auto *LT = U->getContext().getLineTableForUnit(U))
500       if (LT->getFileNameByIndex(
501               FormValue.getAsUnsignedConstant().getValue(),
502               U->getCompilationDir(),
503               DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, File)) {
504         File = '"' + File + '"';
505         Name = File;
506       }
507   } else if (Optional<uint64_t> Val = FormValue.getAsUnsignedConstant())
508     Name = AttributeValueString(Attr, *Val);
509 
510   if (!Name.empty())
511     WithColor(OS, Color) << Name;
512   else if (Attr == DW_AT_decl_line || Attr == DW_AT_call_line)
513     OS << *FormValue.getAsUnsignedConstant();
514   else if (Attr == DW_AT_low_pc &&
515            (FormValue.getAsAddress() ==
516             dwarf::computeTombstoneAddress(U->getAddressByteSize()))) {
517     if (DumpOpts.Verbose) {
518       FormValue.dump(OS, DumpOpts);
519       OS << " (";
520     }
521     OS << "dead code";
522     if (DumpOpts.Verbose)
523       OS << ')';
524   } else if (Attr == DW_AT_high_pc && !DumpOpts.ShowForm && !DumpOpts.Verbose &&
525              FormValue.getAsUnsignedConstant()) {
526     if (DumpOpts.ShowAddresses) {
527       // Print the actual address rather than the offset.
528       uint64_t LowPC, HighPC, Index;
529       if (Die.getLowAndHighPC(LowPC, HighPC, Index))
530         DWARFFormValue::dumpAddress(OS, U->getAddressByteSize(), HighPC);
531       else
532         FormValue.dump(OS, DumpOpts);
533     }
534   } else if (DWARFAttribute::mayHaveLocationList(Attr) &&
535              FormValue.isFormClass(DWARFFormValue::FC_SectionOffset))
536     dumpLocationList(OS, FormValue, U, sizeof(BaseIndent) + Indent + 4,
537                      DumpOpts);
538   else if (FormValue.isFormClass(DWARFFormValue::FC_Exprloc) ||
539            (DWARFAttribute::mayHaveLocationExpr(Attr) &&
540             FormValue.isFormClass(DWARFFormValue::FC_Block)))
541     dumpLocationExpr(OS, FormValue, U, sizeof(BaseIndent) + Indent + 4,
542                      DumpOpts);
543   else
544     FormValue.dump(OS, DumpOpts);
545 
546   std::string Space = DumpOpts.ShowAddresses ? " " : "";
547 
548   // We have dumped the attribute raw value. For some attributes
549   // having both the raw value and the pretty-printed value is
550   // interesting. These attributes are handled below.
551   if (Attr == DW_AT_specification || Attr == DW_AT_abstract_origin) {
552     if (const char *Name =
553             Die.getAttributeValueAsReferencedDie(FormValue).getName(
554                 DINameKind::LinkageName))
555       OS << Space << "\"" << Name << '\"';
556   } else if (Attr == DW_AT_type) {
557     DWARFDie D = Die.getAttributeValueAsReferencedDie(FormValue);
558     if (D && !D.isNULL()) {
559       OS << Space << "\"";
560       DWARFTypePrinter(OS).appendQualifiedName(D);
561       OS << '"';
562     }
563   } else if (Attr == DW_AT_APPLE_property_attribute) {
564     if (Optional<uint64_t> OptVal = FormValue.getAsUnsignedConstant())
565       dumpApplePropertyAttribute(OS, *OptVal);
566   } else if (Attr == DW_AT_ranges) {
567     const DWARFObject &Obj = Die.getDwarfUnit()->getContext().getDWARFObj();
568     // For DW_FORM_rnglistx we need to dump the offset separately, since
569     // we have only dumped the index so far.
570     if (FormValue.getForm() == DW_FORM_rnglistx)
571       if (auto RangeListOffset =
572               U->getRnglistOffset(*FormValue.getAsSectionOffset())) {
573         DWARFFormValue FV = DWARFFormValue::createFromUValue(
574             dwarf::DW_FORM_sec_offset, *RangeListOffset);
575         FV.dump(OS, DumpOpts);
576       }
577     if (auto RangesOrError = Die.getAddressRanges())
578       dumpRanges(Obj, OS, RangesOrError.get(), U->getAddressByteSize(),
579                  sizeof(BaseIndent) + Indent + 4, DumpOpts);
580     else
581       DumpOpts.RecoverableErrorHandler(createStringError(
582           errc::invalid_argument, "decoding address ranges: %s",
583           toString(RangesOrError.takeError()).c_str()));
584   }
585 
586   OS << ")\n";
587 }
588 
589 bool DWARFDie::isSubprogramDIE() const { return getTag() == DW_TAG_subprogram; }
590 
591 bool DWARFDie::isSubroutineDIE() const {
592   auto Tag = getTag();
593   return Tag == DW_TAG_subprogram || Tag == DW_TAG_inlined_subroutine;
594 }
595 
596 Optional<DWARFFormValue> DWARFDie::find(dwarf::Attribute Attr) const {
597   if (!isValid())
598     return None;
599   auto AbbrevDecl = getAbbreviationDeclarationPtr();
600   if (AbbrevDecl)
601     return AbbrevDecl->getAttributeValue(getOffset(), Attr, *U);
602   return None;
603 }
604 
605 Optional<DWARFFormValue>
606 DWARFDie::find(ArrayRef<dwarf::Attribute> Attrs) const {
607   if (!isValid())
608     return None;
609   auto AbbrevDecl = getAbbreviationDeclarationPtr();
610   if (AbbrevDecl) {
611     for (auto Attr : Attrs) {
612       if (auto Value = AbbrevDecl->getAttributeValue(getOffset(), Attr, *U))
613         return Value;
614     }
615   }
616   return None;
617 }
618 
619 Optional<DWARFFormValue>
620 DWARFDie::findRecursively(ArrayRef<dwarf::Attribute> Attrs) const {
621   SmallVector<DWARFDie, 3> Worklist;
622   Worklist.push_back(*this);
623 
624   // Keep track if DIEs already seen to prevent infinite recursion.
625   // Empirically we rarely see a depth of more than 3 when dealing with valid
626   // DWARF. This corresponds to following the DW_AT_abstract_origin and
627   // DW_AT_specification just once.
628   SmallSet<DWARFDie, 3> Seen;
629   Seen.insert(*this);
630 
631   while (!Worklist.empty()) {
632     DWARFDie Die = Worklist.pop_back_val();
633 
634     if (!Die.isValid())
635       continue;
636 
637     if (auto Value = Die.find(Attrs))
638       return Value;
639 
640     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_abstract_origin))
641       if (Seen.insert(D).second)
642         Worklist.push_back(D);
643 
644     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_specification))
645       if (Seen.insert(D).second)
646         Worklist.push_back(D);
647   }
648 
649   return None;
650 }
651 
652 DWARFDie
653 DWARFDie::getAttributeValueAsReferencedDie(dwarf::Attribute Attr) const {
654   if (Optional<DWARFFormValue> F = find(Attr))
655     return getAttributeValueAsReferencedDie(*F);
656   return DWARFDie();
657 }
658 
659 DWARFDie
660 DWARFDie::getAttributeValueAsReferencedDie(const DWARFFormValue &V) const {
661   if (auto SpecRef = V.getAsRelativeReference()) {
662     if (SpecRef->Unit)
663       return SpecRef->Unit->getDIEForOffset(SpecRef->Unit->getOffset() + SpecRef->Offset);
664     if (auto SpecUnit = U->getUnitVector().getUnitForOffset(SpecRef->Offset))
665       return SpecUnit->getDIEForOffset(SpecRef->Offset);
666   }
667   return DWARFDie();
668 }
669 
670 Optional<uint64_t> DWARFDie::getRangesBaseAttribute() const {
671   return toSectionOffset(find({DW_AT_rnglists_base, DW_AT_GNU_ranges_base}));
672 }
673 
674 Optional<uint64_t> DWARFDie::getLocBaseAttribute() const {
675   return toSectionOffset(find(DW_AT_loclists_base));
676 }
677 
678 Optional<uint64_t> DWARFDie::getHighPC(uint64_t LowPC) const {
679   uint64_t Tombstone = dwarf::computeTombstoneAddress(U->getAddressByteSize());
680   if (LowPC == Tombstone)
681     return None;
682   if (auto FormValue = find(DW_AT_high_pc)) {
683     if (auto Address = FormValue->getAsAddress()) {
684       // High PC is an address.
685       return Address;
686     }
687     if (auto Offset = FormValue->getAsUnsignedConstant()) {
688       // High PC is an offset from LowPC.
689       return LowPC + *Offset;
690     }
691   }
692   return None;
693 }
694 
695 bool DWARFDie::getLowAndHighPC(uint64_t &LowPC, uint64_t &HighPC,
696                                uint64_t &SectionIndex) const {
697   auto F = find(DW_AT_low_pc);
698   auto LowPcAddr = toSectionedAddress(F);
699   if (!LowPcAddr)
700     return false;
701   if (auto HighPcAddr = getHighPC(LowPcAddr->Address)) {
702     LowPC = LowPcAddr->Address;
703     HighPC = *HighPcAddr;
704     SectionIndex = LowPcAddr->SectionIndex;
705     return true;
706   }
707   return false;
708 }
709 
710 Expected<DWARFAddressRangesVector> DWARFDie::getAddressRanges() const {
711   if (isNULL())
712     return DWARFAddressRangesVector();
713   // Single range specified by low/high PC.
714   uint64_t LowPC, HighPC, Index;
715   if (getLowAndHighPC(LowPC, HighPC, Index))
716     return DWARFAddressRangesVector{{LowPC, HighPC, Index}};
717 
718   Optional<DWARFFormValue> Value = find(DW_AT_ranges);
719   if (Value) {
720     if (Value->getForm() == DW_FORM_rnglistx)
721       return U->findRnglistFromIndex(*Value->getAsSectionOffset());
722     return U->findRnglistFromOffset(*Value->getAsSectionOffset());
723   }
724   return DWARFAddressRangesVector();
725 }
726 
727 bool DWARFDie::addressRangeContainsAddress(const uint64_t Address) const {
728   auto RangesOrError = getAddressRanges();
729   if (!RangesOrError) {
730     llvm::consumeError(RangesOrError.takeError());
731     return false;
732   }
733 
734   for (const auto &R : RangesOrError.get())
735     if (R.LowPC <= Address && Address < R.HighPC)
736       return true;
737   return false;
738 }
739 
740 Expected<DWARFLocationExpressionsVector>
741 DWARFDie::getLocations(dwarf::Attribute Attr) const {
742   Optional<DWARFFormValue> Location = find(Attr);
743   if (!Location)
744     return createStringError(inconvertibleErrorCode(), "No %s",
745                              dwarf::AttributeString(Attr).data());
746 
747   if (Optional<uint64_t> Off = Location->getAsSectionOffset()) {
748     uint64_t Offset = *Off;
749 
750     if (Location->getForm() == DW_FORM_loclistx) {
751       if (auto LoclistOffset = U->getLoclistOffset(Offset))
752         Offset = *LoclistOffset;
753       else
754         return createStringError(inconvertibleErrorCode(),
755                                  "Loclist table not found");
756     }
757     return U->findLoclistFromOffset(Offset);
758   }
759 
760   if (Optional<ArrayRef<uint8_t>> Expr = Location->getAsBlock()) {
761     return DWARFLocationExpressionsVector{
762         DWARFLocationExpression{None, to_vector<4>(*Expr)}};
763   }
764 
765   return createStringError(
766       inconvertibleErrorCode(), "Unsupported %s encoding: %s",
767       dwarf::AttributeString(Attr).data(),
768       dwarf::FormEncodingString(Location->getForm()).data());
769 }
770 
771 const char *DWARFDie::getSubroutineName(DINameKind Kind) const {
772   if (!isSubroutineDIE())
773     return nullptr;
774   return getName(Kind);
775 }
776 
777 const char *DWARFDie::getName(DINameKind Kind) const {
778   if (!isValid() || Kind == DINameKind::None)
779     return nullptr;
780   // Try to get mangled name only if it was asked for.
781   if (Kind == DINameKind::LinkageName) {
782     if (auto Name = getLinkageName())
783       return Name;
784   }
785   return getShortName();
786 }
787 
788 const char *DWARFDie::getShortName() const {
789   if (!isValid())
790     return nullptr;
791 
792   return dwarf::toString(findRecursively(dwarf::DW_AT_name), nullptr);
793 }
794 
795 const char *DWARFDie::getLinkageName() const {
796   if (!isValid())
797     return nullptr;
798 
799   return dwarf::toString(findRecursively({dwarf::DW_AT_MIPS_linkage_name,
800                                           dwarf::DW_AT_linkage_name}),
801                          nullptr);
802 }
803 
804 uint64_t DWARFDie::getDeclLine() const {
805   return toUnsigned(findRecursively(DW_AT_decl_line), 0);
806 }
807 
808 std::string
809 DWARFDie::getDeclFile(DILineInfoSpecifier::FileLineInfoKind Kind) const {
810   if (auto FormValue = findRecursively(DW_AT_decl_file))
811     if (auto OptString = FormValue->getAsFile(Kind))
812       return *OptString;
813   return {};
814 }
815 
816 void DWARFDie::getCallerFrame(uint32_t &CallFile, uint32_t &CallLine,
817                               uint32_t &CallColumn,
818                               uint32_t &CallDiscriminator) const {
819   CallFile = toUnsigned(find(DW_AT_call_file), 0);
820   CallLine = toUnsigned(find(DW_AT_call_line), 0);
821   CallColumn = toUnsigned(find(DW_AT_call_column), 0);
822   CallDiscriminator = toUnsigned(find(DW_AT_GNU_discriminator), 0);
823 }
824 
825 /// Helper to dump a DIE with all of its parents, but no siblings.
826 static unsigned dumpParentChain(DWARFDie Die, raw_ostream &OS, unsigned Indent,
827                                 DIDumpOptions DumpOpts, unsigned Depth = 0) {
828   if (!Die)
829     return Indent;
830   if (DumpOpts.ParentRecurseDepth > 0 && Depth >= DumpOpts.ParentRecurseDepth)
831     return Indent;
832   Indent = dumpParentChain(Die.getParent(), OS, Indent, DumpOpts, Depth + 1);
833   Die.dump(OS, Indent, DumpOpts);
834   return Indent + 2;
835 }
836 
837 void DWARFDie::dump(raw_ostream &OS, unsigned Indent,
838                     DIDumpOptions DumpOpts) const {
839   if (!isValid())
840     return;
841   DWARFDataExtractor debug_info_data = U->getDebugInfoExtractor();
842   const uint64_t Offset = getOffset();
843   uint64_t offset = Offset;
844   if (DumpOpts.ShowParents) {
845     DIDumpOptions ParentDumpOpts = DumpOpts;
846     ParentDumpOpts.ShowParents = false;
847     ParentDumpOpts.ShowChildren = false;
848     Indent = dumpParentChain(getParent(), OS, Indent, ParentDumpOpts);
849   }
850 
851   if (debug_info_data.isValidOffset(offset)) {
852     uint32_t abbrCode = debug_info_data.getULEB128(&offset);
853     if (DumpOpts.ShowAddresses)
854       WithColor(OS, HighlightColor::Address).get()
855           << format("\n0x%8.8" PRIx64 ": ", Offset);
856 
857     if (abbrCode) {
858       auto AbbrevDecl = getAbbreviationDeclarationPtr();
859       if (AbbrevDecl) {
860         WithColor(OS, HighlightColor::Tag).get().indent(Indent)
861             << formatv("{0}", getTag());
862         if (DumpOpts.Verbose)
863           OS << format(" [%u] %c", abbrCode,
864                        AbbrevDecl->hasChildren() ? '*' : ' ');
865         OS << '\n';
866 
867         // Dump all data in the DIE for the attributes.
868         for (const DWARFAttribute &AttrValue : attributes())
869           dumpAttribute(OS, *this, AttrValue, Indent, DumpOpts);
870 
871         if (DumpOpts.ShowChildren && DumpOpts.ChildRecurseDepth > 0) {
872           DWARFDie Child = getFirstChild();
873           DumpOpts.ChildRecurseDepth--;
874           DIDumpOptions ChildDumpOpts = DumpOpts;
875           ChildDumpOpts.ShowParents = false;
876           while (Child) {
877             Child.dump(OS, Indent + 2, ChildDumpOpts);
878             Child = Child.getSibling();
879           }
880         }
881       } else {
882         OS << "Abbreviation code not found in 'debug_abbrev' class for code: "
883            << abbrCode << '\n';
884       }
885     } else {
886       OS.indent(Indent) << "NULL\n";
887     }
888   }
889 }
890 
891 LLVM_DUMP_METHOD void DWARFDie::dump() const { dump(llvm::errs(), 0); }
892 
893 DWARFDie DWARFDie::getParent() const {
894   if (isValid())
895     return U->getParent(Die);
896   return DWARFDie();
897 }
898 
899 DWARFDie DWARFDie::getSibling() const {
900   if (isValid())
901     return U->getSibling(Die);
902   return DWARFDie();
903 }
904 
905 DWARFDie DWARFDie::getPreviousSibling() const {
906   if (isValid())
907     return U->getPreviousSibling(Die);
908   return DWARFDie();
909 }
910 
911 DWARFDie DWARFDie::getFirstChild() const {
912   if (isValid())
913     return U->getFirstChild(Die);
914   return DWARFDie();
915 }
916 
917 DWARFDie DWARFDie::getLastChild() const {
918   if (isValid())
919     return U->getLastChild(Die);
920   return DWARFDie();
921 }
922 
923 iterator_range<DWARFDie::attribute_iterator> DWARFDie::attributes() const {
924   return make_range(attribute_iterator(*this, false),
925                     attribute_iterator(*this, true));
926 }
927 
928 DWARFDie::attribute_iterator::attribute_iterator(DWARFDie D, bool End)
929     : Die(D), Index(0) {
930   auto AbbrDecl = Die.getAbbreviationDeclarationPtr();
931   assert(AbbrDecl && "Must have abbreviation declaration");
932   if (End) {
933     // This is the end iterator so we set the index to the attribute count.
934     Index = AbbrDecl->getNumAttributes();
935   } else {
936     // This is the begin iterator so we extract the value for this->Index.
937     AttrValue.Offset = D.getOffset() + AbbrDecl->getCodeByteSize();
938     updateForIndex(*AbbrDecl, 0);
939   }
940 }
941 
942 void DWARFDie::attribute_iterator::updateForIndex(
943     const DWARFAbbreviationDeclaration &AbbrDecl, uint32_t I) {
944   Index = I;
945   // AbbrDecl must be valid before calling this function.
946   auto NumAttrs = AbbrDecl.getNumAttributes();
947   if (Index < NumAttrs) {
948     AttrValue.Attr = AbbrDecl.getAttrByIndex(Index);
949     // Add the previous byte size of any previous attribute value.
950     AttrValue.Offset += AttrValue.ByteSize;
951     uint64_t ParseOffset = AttrValue.Offset;
952     if (AbbrDecl.getAttrIsImplicitConstByIndex(Index))
953       AttrValue.Value = DWARFFormValue::createFromSValue(
954           AbbrDecl.getFormByIndex(Index),
955           AbbrDecl.getAttrImplicitConstValueByIndex(Index));
956     else {
957       auto U = Die.getDwarfUnit();
958       assert(U && "Die must have valid DWARF unit");
959       AttrValue.Value = DWARFFormValue::createFromUnit(
960           AbbrDecl.getFormByIndex(Index), U, &ParseOffset);
961     }
962     AttrValue.ByteSize = ParseOffset - AttrValue.Offset;
963   } else {
964     assert(Index == NumAttrs && "Indexes should be [0, NumAttrs) only");
965     AttrValue = {};
966   }
967 }
968 
969 DWARFDie::attribute_iterator &DWARFDie::attribute_iterator::operator++() {
970   if (auto AbbrDecl = Die.getAbbreviationDeclarationPtr())
971     updateForIndex(*AbbrDecl, Index + 1);
972   return *this;
973 }
974 
975 bool DWARFAttribute::mayHaveLocationList(dwarf::Attribute Attr) {
976   switch(Attr) {
977   case DW_AT_location:
978   case DW_AT_string_length:
979   case DW_AT_return_addr:
980   case DW_AT_data_member_location:
981   case DW_AT_frame_base:
982   case DW_AT_static_link:
983   case DW_AT_segment:
984   case DW_AT_use_location:
985   case DW_AT_vtable_elem_location:
986     return true;
987   default:
988     return false;
989   }
990 }
991 
992 bool DWARFAttribute::mayHaveLocationExpr(dwarf::Attribute Attr) {
993   switch (Attr) {
994   // From the DWARF v5 specification.
995   case DW_AT_location:
996   case DW_AT_byte_size:
997   case DW_AT_bit_offset:
998   case DW_AT_bit_size:
999   case DW_AT_string_length:
1000   case DW_AT_lower_bound:
1001   case DW_AT_return_addr:
1002   case DW_AT_bit_stride:
1003   case DW_AT_upper_bound:
1004   case DW_AT_count:
1005   case DW_AT_data_member_location:
1006   case DW_AT_frame_base:
1007   case DW_AT_segment:
1008   case DW_AT_static_link:
1009   case DW_AT_use_location:
1010   case DW_AT_vtable_elem_location:
1011   case DW_AT_allocated:
1012   case DW_AT_associated:
1013   case DW_AT_data_location:
1014   case DW_AT_byte_stride:
1015   case DW_AT_rank:
1016   case DW_AT_call_value:
1017   case DW_AT_call_origin:
1018   case DW_AT_call_target:
1019   case DW_AT_call_target_clobbered:
1020   case DW_AT_call_data_location:
1021   case DW_AT_call_data_value:
1022   // Extensions.
1023   case DW_AT_GNU_call_site_value:
1024   case DW_AT_GNU_call_site_target:
1025     return true;
1026   default:
1027     return false;
1028   }
1029 }
1030