lib/DebugInfo/DWARF/DWARFDie.cpp

   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   ArrayRef<SectionName> SectionNames;
  66   if (DumpOpts.Verbose)
  67     SectionNames = Obj.getSectionNames();
  68
  69   for (const DWARFAddressRange &R : Ranges) {
  70     OS << '\n';
  71     OS.indent(Indent);
  72     R.dump(OS, AddressSize);
  73
  74     DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, R.SectionIndex);
  75   }
  76 }
  77
  78 static void dumpLocation(raw_ostream &OS, DWARFFormValue &FormValue,
  79                          DWARFUnit *U, unsigned Indent,
  80                          DIDumpOptions DumpOpts) {
  81   DWARFContext &Ctx = U->getContext();
  82   const DWARFObject &Obj = Ctx.getDWARFObj();
  83   const MCRegisterInfo *MRI = Ctx.getRegisterInfo();
  84   if (FormValue.isFormClass(DWARFFormValue::FC_Block) ||
  85       FormValue.isFormClass(DWARFFormValue::FC_Exprloc)) {
  86     ArrayRef<uint8_t> Expr = *FormValue.getAsBlock();
  87     DataExtractor Data(StringRef((const char *)Expr.data(), Expr.size()),
  88                        Ctx.isLittleEndian(), 0);
  89     DWARFExpression(Data, U->getVersion(), U->getAddressByteSize())
  90         .print(OS, MRI, U);
  91     return;
  92   }
  93
  94   FormValue.dump(OS, DumpOpts);
  95   const auto &DumpLL = [&](auto ExpectedLL) {
  96     if (ExpectedLL) {
  97       uint64_t BaseAddr = 0;
  98       if (Optional<object::SectionedAddress> BA = U->getBaseAddress())
  99         BaseAddr = BA->Address;
 100       ExpectedLL->dump(OS, BaseAddr, Ctx.isLittleEndian(), Obj.getAddressSize(),
 101                        MRI, U, Indent);
 102     } else {
 103       OS << '\n';
 104       OS.indent(Indent);
 105       OS << formatv("error extracting location list: {0}",
 106                     fmt_consume(ExpectedLL.takeError()));
 107     }
 108   };
 109   if (FormValue.isFormClass(DWARFFormValue::FC_SectionOffset)) {
 110     uint64_t Offset = *FormValue.getAsSectionOffset();
 111     if (!U->isDWOUnit() && !U->getLocSection()->Data.empty()) {
 112       DWARFDebugLoc DebugLoc;
 113       DWARFDataExtractor Data(Obj, *U->getLocSection(), Ctx.isLittleEndian(),
 114                               Obj.getAddressSize());
 115       DumpLL(DebugLoc.parseOneLocationList(Data, &Offset));
 116       return;
 117     }
 118
 119     bool UseLocLists = !U->isDWOUnit();
 120     StringRef LoclistsSectionData =
 121         UseLocLists ? Obj.getLoclistsSection().Data : U->getLocSectionData();
 122
 123     if (!LoclistsSectionData.empty()) {
 124       DataExtractor Data(LoclistsSectionData, Ctx.isLittleEndian(),
 125                          Obj.getAddressSize());
 126
 127       // Old-style location list were used in DWARF v4 (.debug_loc.dwo section).
 128       // Modern locations list (.debug_loclists) are used starting from v5.
 129       // Ideally we should take the version from the .debug_loclists section
 130       // header, but using CU's version for simplicity.
 131       DumpLL(DWARFDebugLoclists::parseOneLocationList(
 132           Data, &Offset, UseLocLists ? U->getVersion() : 4));
 133     }
 134   }
 135 }
 136
 137 /// Dump the name encoded in the type tag.
 138 static void dumpTypeTagName(raw_ostream &OS, dwarf::Tag T) {
 139   StringRef TagStr = TagString(T);
 140   if (!TagStr.startswith("DW_TAG_") || !TagStr.endswith("_type"))
 141     return;
 142   OS << TagStr.substr(7, TagStr.size() - 12) << " ";
 143 }
 144
 145 static void dumpArrayType(raw_ostream &OS, const DWARFDie &D) {
 146   Optional<uint64_t> Bound;
 147   for (const DWARFDie &C : D.children())
 148     if (C.getTag() == DW_TAG_subrange_type) {
 149       Optional<uint64_t> LB;
 150       Optional<uint64_t> Count;
 151       Optional<uint64_t> UB;
 152       Optional<unsigned> DefaultLB;
 153       if (Optional<DWARFFormValue> L = C.find(DW_AT_lower_bound))
 154         LB = L->getAsUnsignedConstant();
 155       if (Optional<DWARFFormValue> CountV = C.find(DW_AT_count))
 156         Count = CountV->getAsUnsignedConstant();
 157       if (Optional<DWARFFormValue> UpperV = C.find(DW_AT_upper_bound))
 158         UB = UpperV->getAsUnsignedConstant();
 159       if (Optional<DWARFFormValue> LV =
 160               D.getDwarfUnit()->getUnitDIE().find(DW_AT_language))
 161         if (Optional<uint64_t> LC = LV->getAsUnsignedConstant())
 162           if ((DefaultLB =
 163                    LanguageLowerBound(static_cast<dwarf::SourceLanguage>(*LC))))
 164             if (LB && *LB == *DefaultLB)
 165               LB = None;
 166       if (!LB && !Count && !UB)
 167         OS << "[]";
 168       else if (!LB && (Count || UB) && DefaultLB)
 169         OS << '[' << (Count ? *Count : *UB - *DefaultLB + 1) << ']';
 170       else {
 171         OS << "[[";
 172         if (LB)
 173           OS << *LB;
 174         else
 175           OS << '?';
 176         OS << ", ";
 177         if (Count)
 178           if (LB)
 179             OS << *LB + *Count;
 180           else
 181             OS << "? + " << *Count;
 182         else if (UB)
 183           OS << *UB + 1;
 184         else
 185           OS << '?';
 186         OS << ")]";
 187       }
 188     }
 189 }
 190
 191 /// Recursively dump the DIE type name when applicable.
 192 static void dumpTypeName(raw_ostream &OS, const DWARFDie &D) {
 193   if (!D.isValid())
 194     return;
 195
 196   if (const char *Name = D.getName(DINameKind::LinkageName)) {
 197     OS << Name;
 198     return;
 199   }
 200
 201   // FIXME: We should have pretty printers per language. Currently we print
 202   // everything as if it was C++ and fall back to the TAG type name.
 203   const dwarf::Tag T = D.getTag();
 204   switch (T) {
 205   case DW_TAG_array_type:
 206   case DW_TAG_pointer_type:
 207   case DW_TAG_ptr_to_member_type:
 208   case DW_TAG_reference_type:
 209   case DW_TAG_rvalue_reference_type:
 210   case DW_TAG_subroutine_type:
 211     break;
 212   default:
 213     dumpTypeTagName(OS, T);
 214   }
 215
 216   // Follow the DW_AT_type if possible.
 217   DWARFDie TypeDie = D.getAttributeValueAsReferencedDie(DW_AT_type);
 218   dumpTypeName(OS, TypeDie);
 219
 220   switch (T) {
 221   case DW_TAG_subroutine_type: {
 222     if (!TypeDie)
 223       OS << "void";
 224     OS << '(';
 225     bool First = true;
 226     for (const DWARFDie &C : D.children()) {
 227       if (C.getTag() == DW_TAG_formal_parameter) {
 228         if (!First)
 229           OS << ", ";
 230         First = false;
 231         dumpTypeName(OS, C.getAttributeValueAsReferencedDie(DW_AT_type));
 232       }
 233     }
 234     OS << ')';
 235     break;
 236   }
 237   case DW_TAG_array_type: {
 238     dumpArrayType(OS, D);
 239     break;
 240   }
 241   case DW_TAG_pointer_type:
 242     OS << '*';
 243     break;
 244   case DW_TAG_ptr_to_member_type:
 245     if (DWARFDie Cont =
 246             D.getAttributeValueAsReferencedDie(DW_AT_containing_type)) {
 247       dumpTypeName(OS << ' ', Cont);
 248       OS << "::";
 249     }
 250     OS << '*';
 251     break;
 252   case DW_TAG_reference_type:
 253     OS << '&';
 254     break;
 255   case DW_TAG_rvalue_reference_type:
 256     OS << "&&";
 257     break;
 258   default:
 259     break;
 260   }
 261 }
 262
 263 static void dumpAttribute(raw_ostream &OS, const DWARFDie &Die,
 264                           uint64_t *OffsetPtr, dwarf::Attribute Attr,
 265                           dwarf::Form Form, unsigned Indent,
 266                           DIDumpOptions DumpOpts) {
 267   if (!Die.isValid())
 268     return;
 269   const char BaseIndent[] = "            ";
 270   OS << BaseIndent;
 271   OS.indent(Indent + 2);
 272   WithColor(OS, HighlightColor::Attribute) << formatv("{0}", Attr);
 273
 274   if (DumpOpts.Verbose || DumpOpts.ShowForm)
 275     OS << formatv(" [{0}]", Form);
 276
 277   DWARFUnit *U = Die.getDwarfUnit();
 278   DWARFFormValue FormValue = DWARFFormValue::createFromUnit(Form, U, OffsetPtr);
 279
 280   OS << "\t(";
 281
 282   StringRef Name;
 283   std::string File;
 284   auto Color = HighlightColor::Enumerator;
 285   if (Attr == DW_AT_decl_file || Attr == DW_AT_call_file) {
 286     Color = HighlightColor::String;
 287     if (const auto *LT = U->getContext().getLineTableForUnit(U))
 288       if (LT->getFileNameByIndex(
 289               FormValue.getAsUnsignedConstant().getValue(),
 290               U->getCompilationDir(),
 291               DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, File)) {
 292         File = '"' + File + '"';
 293         Name = File;
 294       }
 295   } else if (Optional<uint64_t> Val = FormValue.getAsUnsignedConstant())
 296     Name = AttributeValueString(Attr, *Val);
 297
 298   if (!Name.empty())
 299     WithColor(OS, Color) << Name;
 300   else if (Attr == DW_AT_decl_line || Attr == DW_AT_call_line)
 301     OS << *FormValue.getAsUnsignedConstant();
 302   else if (Attr == DW_AT_high_pc && !DumpOpts.ShowForm && !DumpOpts.Verbose &&
 303            FormValue.getAsUnsignedConstant()) {
 304     if (DumpOpts.ShowAddresses) {
 305       // Print the actual address rather than the offset.
 306       uint64_t LowPC, HighPC, Index;
 307       if (Die.getLowAndHighPC(LowPC, HighPC, Index))
 308         OS << format("0x%016" PRIx64, HighPC);
 309       else
 310         FormValue.dump(OS, DumpOpts);
 311     }
 312   } else if (DWARFAttribute::mayHaveLocationDescription(Attr))
 313     dumpLocation(OS, FormValue, U, sizeof(BaseIndent) + Indent + 4, DumpOpts);
 314   else
 315     FormValue.dump(OS, DumpOpts);
 316
 317   std::string Space = DumpOpts.ShowAddresses ? " " : "";
 318
 319   // We have dumped the attribute raw value. For some attributes
 320   // having both the raw value and the pretty-printed value is
 321   // interesting. These attributes are handled below.
 322   if (Attr == DW_AT_specification || Attr == DW_AT_abstract_origin) {
 323     if (const char *Name =
 324             Die.getAttributeValueAsReferencedDie(FormValue).getName(
 325                 DINameKind::LinkageName))
 326       OS << Space << "\"" << Name << '\"';
 327   } else if (Attr == DW_AT_type) {
 328     OS << Space << "\"";
 329     dumpTypeName(OS, Die.getAttributeValueAsReferencedDie(FormValue));
 330     OS << '"';
 331   } else if (Attr == DW_AT_APPLE_property_attribute) {
 332     if (Optional<uint64_t> OptVal = FormValue.getAsUnsignedConstant())
 333       dumpApplePropertyAttribute(OS, *OptVal);
 334   } else if (Attr == DW_AT_ranges) {
 335     const DWARFObject &Obj = Die.getDwarfUnit()->getContext().getDWARFObj();
 336     // For DW_FORM_rnglistx we need to dump the offset separately, since
 337     // we have only dumped the index so far.
 338     if (FormValue.getForm() == DW_FORM_rnglistx)
 339       if (auto RangeListOffset =
 340               U->getRnglistOffset(*FormValue.getAsSectionOffset())) {
 341         DWARFFormValue FV = DWARFFormValue::createFromUValue(
 342             dwarf::DW_FORM_sec_offset, *RangeListOffset);
 343         FV.dump(OS, DumpOpts);
 344       }
 345     if (auto RangesOrError = Die.getAddressRanges())
 346       dumpRanges(Obj, OS, RangesOrError.get(), U->getAddressByteSize(),
 347                  sizeof(BaseIndent) + Indent + 4, DumpOpts);
 348     else
 349       WithColor::error() << "decoding address ranges: "
 350                          << toString(RangesOrError.takeError()) << '\n';
 351   }
 352
 353   OS << ")\n";
 354 }
 355
 356 bool DWARFDie::isSubprogramDIE() const { return getTag() == DW_TAG_subprogram; }
 357
 358 bool DWARFDie::isSubroutineDIE() const {
 359   auto Tag = getTag();
 360   return Tag == DW_TAG_subprogram || Tag == DW_TAG_inlined_subroutine;
 361 }
 362
 363 Optional<DWARFFormValue> DWARFDie::find(dwarf::Attribute Attr) const {
 364   if (!isValid())
 365     return None;
 366   auto AbbrevDecl = getAbbreviationDeclarationPtr();
 367   if (AbbrevDecl)
 368     return AbbrevDecl->getAttributeValue(getOffset(), Attr, *U);
 369   return None;
 370 }
 371
 372 Optional<DWARFFormValue>
 373 DWARFDie::find(ArrayRef<dwarf::Attribute> Attrs) const {
 374   if (!isValid())
 375     return None;
 376   auto AbbrevDecl = getAbbreviationDeclarationPtr();
 377   if (AbbrevDecl) {
 378     for (auto Attr : Attrs) {
 379       if (auto Value = AbbrevDecl->getAttributeValue(getOffset(), Attr, *U))
 380         return Value;
 381     }
 382   }
 383   return None;
 384 }
 385
 386 Optional<DWARFFormValue>
 387 DWARFDie::findRecursively(ArrayRef<dwarf::Attribute> Attrs) const {
 388   std::vector<DWARFDie> Worklist;
 389   Worklist.push_back(*this);
 390
 391   // Keep track if DIEs already seen to prevent infinite recursion.
 392   // Empirically we rarely see a depth of more than 3 when dealing with valid
 393   // DWARF. This corresponds to following the DW_AT_abstract_origin and
 394   // DW_AT_specification just once.
 395   SmallSet<DWARFDie, 3> Seen;
 396   Seen.insert(*this);
 397
 398   while (!Worklist.empty()) {
 399     DWARFDie Die = Worklist.back();
 400     Worklist.pop_back();
 401
 402     if (!Die.isValid())
 403       continue;
 404
 405     if (auto Value = Die.find(Attrs))
 406       return Value;
 407
 408     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_abstract_origin))
 409       if (Seen.insert(D).second)
 410         Worklist.push_back(D);
 411
 412     if (auto D = Die.getAttributeValueAsReferencedDie(DW_AT_specification))
 413       if (Seen.insert(D).second)
 414         Worklist.push_back(D);
 415   }
 416
 417   return None;
 418 }
 419
 420 DWARFDie
 421 DWARFDie::getAttributeValueAsReferencedDie(dwarf::Attribute Attr) const {
 422   if (Optional<DWARFFormValue> F = find(Attr))
 423     return getAttributeValueAsReferencedDie(*F);
 424   return DWARFDie();
 425 }
 426
 427 DWARFDie
 428 DWARFDie::getAttributeValueAsReferencedDie(const DWARFFormValue &V) const {
 429   if (auto SpecRef = V.getAsRelativeReference()) {
 430     if (SpecRef->Unit)
 431       return SpecRef->Unit->getDIEForOffset(SpecRef->Unit->getOffset() + SpecRef->Offset);
 432     if (auto SpecUnit = U->getUnitVector().getUnitForOffset(SpecRef->Offset))
 433       return SpecUnit->getDIEForOffset(SpecRef->Offset);
 434   }
 435   return DWARFDie();
 436 }
 437
 438 Optional<uint64_t> DWARFDie::getRangesBaseAttribute() const {
 439   return toSectionOffset(find({DW_AT_rnglists_base, DW_AT_GNU_ranges_base}));
 440 }
 441
 442 Optional<uint64_t> DWARFDie::getHighPC(uint64_t LowPC) const {
 443   if (auto FormValue = find(DW_AT_high_pc)) {
 444     if (auto Address = FormValue->getAsAddress()) {
 445       // High PC is an address.
 446       return Address;
 447     }
 448     if (auto Offset = FormValue->getAsUnsignedConstant()) {
 449       // High PC is an offset from LowPC.
 450       return LowPC + *Offset;
 451     }
 452   }
 453   return None;
 454 }
 455
 456 bool DWARFDie::getLowAndHighPC(uint64_t &LowPC, uint64_t &HighPC,
 457                                uint64_t &SectionIndex) const {
 458   auto F = find(DW_AT_low_pc);
 459   auto LowPcAddr = toSectionedAddress(F);
 460   if (!LowPcAddr)
 461     return false;
 462   if (auto HighPcAddr = getHighPC(LowPcAddr->Address)) {
 463     LowPC = LowPcAddr->Address;
 464     HighPC = *HighPcAddr;
 465     SectionIndex = LowPcAddr->SectionIndex;
 466     return true;
 467   }
 468   return false;
 469 }
 470
 471 Expected<DWARFAddressRangesVector> DWARFDie::getAddressRanges() const {
 472   if (isNULL())
 473     return DWARFAddressRangesVector();
 474   // Single range specified by low/high PC.
 475   uint64_t LowPC, HighPC, Index;
 476   if (getLowAndHighPC(LowPC, HighPC, Index))
 477     return DWARFAddressRangesVector{{LowPC, HighPC, Index}};
 478
 479   Optional<DWARFFormValue> Value = find(DW_AT_ranges);
 480   if (Value) {
 481     if (Value->getForm() == DW_FORM_rnglistx)
 482       return U->findRnglistFromIndex(*Value->getAsSectionOffset());
 483     return U->findRnglistFromOffset(*Value->getAsSectionOffset());
 484   }
 485   return DWARFAddressRangesVector();
 486 }
 487
 488 void DWARFDie::collectChildrenAddressRanges(
 489     DWARFAddressRangesVector &Ranges) const {
 490   if (isNULL())
 491     return;
 492   if (isSubprogramDIE()) {
 493     if (auto DIERangesOrError = getAddressRanges())
 494       Ranges.insert(Ranges.end(), DIERangesOrError.get().begin(),
 495                     DIERangesOrError.get().end());
 496     else
 497       llvm::consumeError(DIERangesOrError.takeError());
 498   }
 499
 500   for (auto Child : children())
 501     Child.collectChildrenAddressRanges(Ranges);
 502 }
 503
 504 bool DWARFDie::addressRangeContainsAddress(const uint64_t Address) const {
 505   auto RangesOrError = getAddressRanges();
 506   if (!RangesOrError) {
 507     llvm::consumeError(RangesOrError.takeError());
 508     return false;
 509   }
 510
 511   for (const auto &R : RangesOrError.get())
 512     if (R.LowPC <= Address && Address < R.HighPC)
 513       return true;
 514   return false;
 515 }
 516
 517 const char *DWARFDie::getSubroutineName(DINameKind Kind) const {
 518   if (!isSubroutineDIE())
 519     return nullptr;
 520   return getName(Kind);
 521 }
 522
 523 const char *DWARFDie::getName(DINameKind Kind) const {
 524   if (!isValid() || Kind == DINameKind::None)
 525     return nullptr;
 526   // Try to get mangled name only if it was asked for.
 527   if (Kind == DINameKind::LinkageName) {
 528     if (auto Name = dwarf::toString(
 529             findRecursively({DW_AT_MIPS_linkage_name, DW_AT_linkage_name}),
 530             nullptr))
 531       return Name;
 532   }
 533   if (auto Name = dwarf::toString(findRecursively(DW_AT_name), nullptr))
 534     return Name;
 535   return nullptr;
 536 }
 537
 538 uint64_t DWARFDie::getDeclLine() const {
 539   return toUnsigned(findRecursively(DW_AT_decl_line), 0);
 540 }
 541
 542 void DWARFDie::getCallerFrame(uint32_t &CallFile, uint32_t &CallLine,
 543                               uint32_t &CallColumn,
 544                               uint32_t &CallDiscriminator) const {
 545   CallFile = toUnsigned(find(DW_AT_call_file), 0);
 546   CallLine = toUnsigned(find(DW_AT_call_line), 0);
 547   CallColumn = toUnsigned(find(DW_AT_call_column), 0);
 548   CallDiscriminator = toUnsigned(find(DW_AT_GNU_discriminator), 0);
 549 }
 550
 551 /// Helper to dump a DIE with all of its parents, but no siblings.
 552 static unsigned dumpParentChain(DWARFDie Die, raw_ostream &OS, unsigned Indent,
 553                                 DIDumpOptions DumpOpts, unsigned Depth = 0) {
 554   if (!Die)
 555     return Indent;
 556   if (DumpOpts.ParentRecurseDepth > 0 && Depth >= DumpOpts.ParentRecurseDepth)
 557     return Indent;
 558   Indent = dumpParentChain(Die.getParent(), OS, Indent, DumpOpts, Depth + 1);
 559   Die.dump(OS, Indent, DumpOpts);
 560   return Indent + 2;
 561 }
 562
 563 void DWARFDie::dump(raw_ostream &OS, unsigned Indent,
 564                     DIDumpOptions DumpOpts) const {
 565   if (!isValid())
 566     return;
 567   DWARFDataExtractor debug_info_data = U->getDebugInfoExtractor();
 568   const uint64_t Offset = getOffset();
 569   uint64_t offset = Offset;
 570   if (DumpOpts.ShowParents) {
 571     DIDumpOptions ParentDumpOpts = DumpOpts;
 572     ParentDumpOpts.ShowParents = false;
 573     ParentDumpOpts.ShowChildren = false;
 574     Indent = dumpParentChain(getParent(), OS, Indent, ParentDumpOpts);
 575   }
 576
 577   if (debug_info_data.isValidOffset(offset)) {
 578     uint32_t abbrCode = debug_info_data.getULEB128(&offset);
 579     if (DumpOpts.ShowAddresses)
 580       WithColor(OS, HighlightColor::Address).get()
 581           << format("\n0x%8.8" PRIx64 ": ", Offset);
 582
 583     if (abbrCode) {
 584       auto AbbrevDecl = getAbbreviationDeclarationPtr();
 585       if (AbbrevDecl) {
 586         WithColor(OS, HighlightColor::Tag).get().indent(Indent)
 587             << formatv("{0}", getTag());
 588         if (DumpOpts.Verbose)
 589           OS << format(" [%u] %c", abbrCode,
 590                        AbbrevDecl->hasChildren() ? '*' : ' ');
 591         OS << '\n';
 592
 593         // Dump all data in the DIE for the attributes.
 594         for (const auto &AttrSpec : AbbrevDecl->attributes()) {
 595           if (AttrSpec.Form == DW_FORM_implicit_const) {
 596             // We are dumping .debug_info section ,
 597             // implicit_const attribute values are not really stored here,
 598             // but in .debug_abbrev section. So we just skip such attrs.
 599             continue;
 600           }
 601           dumpAttribute(OS, *this, &offset, AttrSpec.Attr, AttrSpec.Form,
 602                         Indent, DumpOpts);
 603         }
 604
 605         DWARFDie child = getFirstChild();
 606         if (DumpOpts.ShowChildren && DumpOpts.ChildRecurseDepth > 0 && child) {
 607           DumpOpts.ChildRecurseDepth--;
 608           DIDumpOptions ChildDumpOpts = DumpOpts;
 609           ChildDumpOpts.ShowParents = false;
 610           while (child) {
 611             child.dump(OS, Indent + 2, ChildDumpOpts);
 612             child = child.getSibling();
 613           }
 614         }
 615       } else {
 616         OS << "Abbreviation code not found in 'debug_abbrev' class for code: "
 617            << abbrCode << '\n';
 618       }
 619     } else {
 620       OS.indent(Indent) << "NULL\n";
 621     }
 622   }
 623 }
 624
 625 LLVM_DUMP_METHOD void DWARFDie::dump() const { dump(llvm::errs(), 0); }
 626
 627 DWARFDie DWARFDie::getParent() const {
 628   if (isValid())
 629     return U->getParent(Die);
 630   return DWARFDie();
 631 }
 632
 633 DWARFDie DWARFDie::getSibling() const {
 634   if (isValid())
 635     return U->getSibling(Die);
 636   return DWARFDie();
 637 }
 638
 639 DWARFDie DWARFDie::getPreviousSibling() const {
 640   if (isValid())
 641     return U->getPreviousSibling(Die);
 642   return DWARFDie();
 643 }
 644
 645 DWARFDie DWARFDie::getFirstChild() const {
 646   if (isValid())
 647     return U->getFirstChild(Die);
 648   return DWARFDie();
 649 }
 650
 651 DWARFDie DWARFDie::getLastChild() const {
 652   if (isValid())
 653     return U->getLastChild(Die);
 654   return DWARFDie();
 655 }
 656
 657 iterator_range<DWARFDie::attribute_iterator> DWARFDie::attributes() const {
 658   return make_range(attribute_iterator(*this, false),
 659                     attribute_iterator(*this, true));
 660 }
 661
 662 DWARFDie::attribute_iterator::attribute_iterator(DWARFDie D, bool End)
 663     : Die(D), Index(0) {
 664   auto AbbrDecl = Die.getAbbreviationDeclarationPtr();
 665   assert(AbbrDecl && "Must have abbreviation declaration");
 666   if (End) {
 667     // This is the end iterator so we set the index to the attribute count.
 668     Index = AbbrDecl->getNumAttributes();
 669   } else {
 670     // This is the begin iterator so we extract the value for this->Index.
 671     AttrValue.Offset = D.getOffset() + AbbrDecl->getCodeByteSize();
 672     updateForIndex(*AbbrDecl, 0);
 673   }
 674 }
 675
 676 void DWARFDie::attribute_iterator::updateForIndex(
 677     const DWARFAbbreviationDeclaration &AbbrDecl, uint32_t I) {
 678   Index = I;
 679   // AbbrDecl must be valid before calling this function.
 680   auto NumAttrs = AbbrDecl.getNumAttributes();
 681   if (Index < NumAttrs) {
 682     AttrValue.Attr = AbbrDecl.getAttrByIndex(Index);
 683     // Add the previous byte size of any previous attribute value.
 684     AttrValue.Offset += AttrValue.ByteSize;
 685     uint64_t ParseOffset = AttrValue.Offset;
 686     auto U = Die.getDwarfUnit();
 687     assert(U && "Die must have valid DWARF unit");
 688     AttrValue.Value = DWARFFormValue::createFromUnit(
 689         AbbrDecl.getFormByIndex(Index), U, &ParseOffset);
 690     AttrValue.ByteSize = ParseOffset - AttrValue.Offset;
 691   } else {
 692     assert(Index == NumAttrs && "Indexes should be [0, NumAttrs) only");
 693     AttrValue = {};
 694   }
 695 }
 696
 697 DWARFDie::attribute_iterator &DWARFDie::attribute_iterator::operator++() {
 698   if (auto AbbrDecl = Die.getAbbreviationDeclarationPtr())
 699     updateForIndex(*AbbrDecl, Index + 1);
 700   return *this;
 701 }
 702
 703 bool DWARFAttribute::mayHaveLocationDescription(dwarf::Attribute Attr) {
 704   switch (Attr) {
 705   // From the DWARF v5 specification.
 706   case DW_AT_location:
 707   case DW_AT_byte_size:
 708   case DW_AT_bit_size:
 709   case DW_AT_string_length:
 710   case DW_AT_lower_bound:
 711   case DW_AT_return_addr:
 712   case DW_AT_bit_stride:
 713   case DW_AT_upper_bound:
 714   case DW_AT_count:
 715   case DW_AT_data_member_location:
 716   case DW_AT_frame_base:
 717   case DW_AT_segment:
 718   case DW_AT_static_link:
 719   case DW_AT_use_location:
 720   case DW_AT_vtable_elem_location:
 721   case DW_AT_allocated:
 722   case DW_AT_associated:
 723   case DW_AT_byte_stride:
 724   case DW_AT_rank:
 725   case DW_AT_call_value:
 726   case DW_AT_call_origin:
 727   case DW_AT_call_target:
 728   case DW_AT_call_target_clobbered:
 729   case DW_AT_call_data_location:
 730   case DW_AT_call_data_value:
 731   // Extensions.
 732   case DW_AT_GNU_call_site_value:
 733   case DW_AT_GNU_call_site_target:
 734     return true;
 735   default:
 736     return false;
 737   }
 738 }