DWARFLinkerCompileUnit.cpp

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//=== DWARFLinkerCompileUnit.cpp ------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "DWARFLinkerCompileUnit.h"
#include "AcceleratorRecordsSaver.h"
#include "DIEAttributeCloner.h"
#include "DIEGenerator.h"
#include "DependencyTracker.h"
#include "SyntheticTypeNameBuilder.h"
#include "llvm/DWARFLinker/Utils.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugAbbrev.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugMacro.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/Path.h"
#include <utility>
 
using namespace llvm;
using namespace dwarf_linker;
using namespace dwarf_linker::parallel;
 
CompileUnit::CompileUnit(LinkingGlobalData &GlobalData, unsigned ID,
                         StringRef ClangModuleName, DWARFFile &File,
                         OffsetToUnitTy UnitFromOffset,
                         dwarf::FormParams Format, llvm::endianness Endianess)
    : DwarfUnit(GlobalData, ID, ClangModuleName), File(File),
      getUnitFromOffset(UnitFromOffset), Stage(Stage::CreatedNotLoaded),
      AcceleratorRecords(&GlobalData.getAllocator()) {
  UnitName = File.FileName;
  setOutputFormat(Format, Endianess);
  getOrCreateSectionDescriptor(DebugSectionKind::DebugInfo);
}
 
CompileUnit::CompileUnit(LinkingGlobalData &GlobalData, DWARFUnit &OrigUnit,
                         unsigned ID, StringRef ClangModuleName,
                         DWARFFile &File, OffsetToUnitTy UnitFromOffset,
                         dwarf::FormParams Format, llvm::endianness Endianess)
    : DwarfUnit(GlobalData, ID, ClangModuleName), File(File),
      OrigUnit(&OrigUnit), getUnitFromOffset(UnitFromOffset),
      Stage(Stage::CreatedNotLoaded),
      AcceleratorRecords(&GlobalData.getAllocator()) {
  setOutputFormat(Format, Endianess);
  getOrCreateSectionDescriptor(DebugSectionKind::DebugInfo);
 
  DWARFDie CUDie = OrigUnit.getUnitDIE();
  if (!CUDie)
    return;
 
  Language = CUDie.getLanguage();
 
  if (!GlobalData.getOptions().NoODR && Language.has_value() &&
      isODRLanguage(*Language))
    NoODR = false;
 
  if (const char *CUName = CUDie.getName(DINameKind::ShortName))
    UnitName = CUName;
  else
    UnitName = File.FileName;
  SysRoot = dwarf::toStringRef(CUDie.find(dwarf::DW_AT_LLVM_sysroot)).str();
}
 
void CompileUnit::loadLineTable() {
  LineTablePtr = File.Dwarf->getLineTableForUnit(&getOrigUnit());
}
 
void CompileUnit::maybeResetToLoadedStage() {
  // Nothing to reset if stage is less than "Loaded".
  if (getStage() < Stage::Loaded)
    return;
 
  // Note: We need to do erasing for "Loaded" stage because
  // if live analysys failed then we will have "Loaded" stage
  // with marking from "LivenessAnalysisDone" stage partially
  // done. That marking should be cleared.
 
  for (DIEInfo &Info : DieInfoArray)
    Info.unsetFlagsWhichSetDuringLiveAnalysis();
 
  LowPc = std::nullopt;
  HighPc = 0;
  Labels.clear();
  Ranges.clear();
  Dependencies.reset(nullptr);
 
  if (getStage() < Stage::Cloned) {
    setStage(Stage::Loaded);
    return;
  }
 
  AcceleratorRecords.erase();
  AbbreviationsSet.clear();
  Abbreviations.clear();
  OutUnitDIE = nullptr;
  DebugAddrIndexMap.clear();
  StmtSeqListAttributes.clear();
 
  llvm::fill(OutDieOffsetArray, 0);
  llvm::fill(TypeEntries, nullptr);
  eraseSections();
 
  setStage(Stage::CreatedNotLoaded);
}
 
bool CompileUnit::loadInputDIEs() {
  DWARFDie InputUnitDIE = getUnitDIE(false);
  if (!InputUnitDIE)
    return false;
 
  // load input dies, resize Info structures array.
  DieInfoArray.resize(getOrigUnit().getNumDIEs());
  OutDieOffsetArray.resize(getOrigUnit().getNumDIEs(), 0);
  if (!NoODR)
    TypeEntries.resize(getOrigUnit().getNumDIEs());
  return true;
}
 
void CompileUnit::analyzeDWARFStructureRec(const DWARFDebugInfoEntry *DieEntry,
                                           bool IsODRUnavailableFunctionScope) {
  CompileUnit::DIEInfo &DieInfo = getDIEInfo(DieEntry);
 
  for (const DWARFDebugInfoEntry *CurChild = getFirstChildEntry(DieEntry);
       CurChild && CurChild->getAbbreviationDeclarationPtr();
       CurChild = getSiblingEntry(CurChild)) {
    CompileUnit::DIEInfo &ChildInfo = getDIEInfo(CurChild);
    bool ChildIsODRUnavailableFunctionScope = IsODRUnavailableFunctionScope;
 
    if (DieInfo.getIsInMouduleScope())
      ChildInfo.setIsInMouduleScope();
 
    if (DieInfo.getIsInFunctionScope())
      ChildInfo.setIsInFunctionScope();
 
    if (DieInfo.getIsInAnonNamespaceScope())
      ChildInfo.setIsInAnonNamespaceScope();
 
    switch (CurChild->getTag()) {
    case dwarf::DW_TAG_module:
      ChildInfo.setIsInMouduleScope();
      if (DieEntry->getTag() == dwarf::DW_TAG_compile_unit &&
          dwarf::toString(find(CurChild, dwarf::DW_AT_name), "") !=
              getClangModuleName())
        analyzeImportedModule(CurChild);
      break;
    case dwarf::DW_TAG_subprogram:
      ChildInfo.setIsInFunctionScope();
      if (!ChildIsODRUnavailableFunctionScope &&
          !ChildInfo.getIsInMouduleScope()) {
        if (find(CurChild,
                 {dwarf::DW_AT_abstract_origin, dwarf::DW_AT_specification}))
          ChildIsODRUnavailableFunctionScope = true;
      }
      break;
    case dwarf::DW_TAG_namespace: {
      UnitEntryPairTy NamespaceEntry = {this, CurChild};
 
      if (find(CurChild, dwarf::DW_AT_extension))
        NamespaceEntry = NamespaceEntry.getNamespaceOrigin();
 
      if (!NamespaceEntry.CU->find(NamespaceEntry.DieEntry, dwarf::DW_AT_name))
        ChildInfo.setIsInAnonNamespaceScope();
    } break;
    default:
      break;
    }
 
    if (!isClangModule() && !getGlobalData().getOptions().UpdateIndexTablesOnly)
      ChildInfo.setTrackLiveness();
 
    if ((!ChildInfo.getIsInAnonNamespaceScope() &&
         !ChildIsODRUnavailableFunctionScope && !NoODR))
      ChildInfo.setODRAvailable();
 
    if (CurChild->hasChildren())
      analyzeDWARFStructureRec(CurChild, ChildIsODRUnavailableFunctionScope);
  }
}
 
StringEntry *CompileUnit::getFileName(unsigned FileIdx,
                                      StringPool &GlobalStrings) {
  if (LineTablePtr) {
    if (LineTablePtr->hasFileAtIndex(FileIdx)) {
      // Cache the resolved paths based on the index in the line table,
      // because calling realpath is expensive.
      ResolvedPathsMap::const_iterator It = ResolvedFullPaths.find(FileIdx);
      if (It == ResolvedFullPaths.end()) {
        std::string OrigFileName;
        bool FoundFileName = LineTablePtr->getFileNameByIndex(
            FileIdx, getOrigUnit().getCompilationDir(),
            DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath,
            OrigFileName);
        (void)FoundFileName;
        assert(FoundFileName && "Must get file name from line table");
 
        // Second level of caching, this time based on the file's parent
        // path.
        StringRef FileName = sys::path::filename(OrigFileName);
        StringRef ParentPath = sys::path::parent_path(OrigFileName);
 
        // If the ParentPath has not yet been resolved, resolve and cache it for
        // future look-ups.
        StringMap<StringEntry *>::iterator ParentIt =
            ResolvedParentPaths.find(ParentPath);
        if (ParentIt == ResolvedParentPaths.end()) {
          SmallString<256> RealPath;
          sys::fs::real_path(ParentPath, RealPath);
          ParentIt =
              ResolvedParentPaths
                  .insert({ParentPath, GlobalStrings.insert(RealPath).first})
                  .first;
        }
 
        // Join the file name again with the resolved path.
        SmallString<256> ResolvedPath(ParentIt->second->first());
        sys::path::append(ResolvedPath, FileName);
 
        It = ResolvedFullPaths
                 .insert(std::make_pair(
                     FileIdx, GlobalStrings.insert(ResolvedPath).first))
                 .first;
      }
 
      return It->second;
    }
  }
 
  return nullptr;
}
 
llvm::Error CompileUnit::setPriority(uint64_t ObjFileIdx, uint64_t LocalIdx) {
  if (ObjFileIdx > std::numeric_limits<uint32_t>::max())
    return llvm::createStringError("cannot compute priority when number of "
                                   "object files exceeds UINT32_MAX");
  if (LocalIdx > std::numeric_limits<uint32_t>::max())
    return llvm::createStringError("cannot compute priority when number of "
                                   "local index exceeds UINT32_MAX");
 
  Priority = (ObjFileIdx << 32) | LocalIdx;
  return llvm::Error::success();
}
 
void CompileUnit::cleanupDataAfterClonning() {
  AbbreviationsSet.clear();
  ResolvedFullPaths.shrink_and_clear();
  ResolvedParentPaths.clear();
  FileNames.shrink_and_clear();
  DieInfoArray = SmallVector<DIEInfo>();
  OutDieOffsetArray = SmallVector<uint64_t>();
  TypeEntries = SmallVector<TypeEntry *>();
  Dependencies.reset(nullptr);
  StmtSeqListAttributes.clear();
  getOrigUnit().clear();
}
 
bool CompileUnit::getModulePath(const DWARFDebugInfoEntry *DieEntry,
                                SmallVectorImpl<char> &Path) {
  assert(DieEntry->getTag() == dwarf::DW_TAG_module);
 
  SmallVector<StringRef, 4> Names;
  for (const DWARFDebugInfoEntry *CurEntry = DieEntry;
       CurEntry && CurEntry->getTag() == dwarf::DW_TAG_module;
       CurEntry = getParent(CurEntry).getDebugInfoEntry()) {
    StringRef Name = dwarf::toStringRef(find(CurEntry, dwarf::DW_AT_name));
    if (Name.empty())
      return false;
    Names.push_back(Name);
  }
 
  for (StringRef Name : reverse(Names)) {
    Path.append(Name.begin(), Name.end());
    Path.push_back('\0');
  }
 
  return true;
}
 
void CompileUnit::noteModuleAnchors() {
  const DWARFDebugInfoEntry *UnitEntry = getUnitDIE().getDebugInfoEntry();
  assert(UnitEntry && "unit reached cloning without loaded DIEs");
 
  // Find the root, ignoring the skeletons for the imported module.
  const DWARFDebugInfoEntry *Root = nullptr;
  for (const DWARFDebugInfoEntry *CurChild = getFirstChildEntry(UnitEntry);
       CurChild && CurChild->getAbbreviationDeclarationPtr();
       CurChild = getSiblingEntry(CurChild)) {
    if (CurChild->getTag() == dwarf::DW_TAG_module &&
        dwarf::toStringRef(find(CurChild, dwarf::DW_AT_name)) ==
            getClangModuleName()) {
      Root = CurChild;
      break;
    }
  }
  if (!Root)
    return;
 
  SmallString<128> Path;
 
  // Submodules nest inside the module which declares them, so following the
  // DW_TAG_module chain down from the root visits every module this unit
  // describes, without walking the types they contain.
  SmallVector<const DWARFDebugInfoEntry *, 4> WorkList = {Root};
  while (!WorkList.empty()) {
    const DWARFDebugInfoEntry *DieEntry = WorkList.pop_back_val();
 
    for (const DWARFDebugInfoEntry *CurChild = getFirstChildEntry(DieEntry);
         CurChild && CurChild->getAbbreviationDeclarationPtr();
         CurChild = getSiblingEntry(CurChild))
      if (CurChild->getTag() == dwarf::DW_TAG_module)
        WorkList.push_back(CurChild);
 
    Path.clear();
    if (!getModulePath(DieEntry, Path))
      continue;
 
    ModuleAnchor Anchor;
    Anchor.Priority = getPriority();
    if (getDIEInfo(DieEntry).needToPlaceInTypeTable())
      Anchor.TypeName = getDieTypeEntry(DieEntry);
    if (!Anchor.TypeName) {
      // Don't create a dangling reference to a DIE without a type entry or
      // output offset.
      uint64_t OutOffset = getDieOutOffset(DieEntry);
      if (!OutOffset)
        continue;
      Anchor.Section = &getSectionDescriptor(DebugSectionKind::DebugInfo);
      Anchor.LocalOffset = OutOffset;
    }
 
    getGlobalData().getModulePool().set(Path, Anchor);
  }
}
 
/// Collect references to parseable Swift interfaces in imported
/// DW_TAG_module blocks.
void CompileUnit::analyzeImportedModule(const DWARFDebugInfoEntry *DieEntry) {
  if (!Language || Language != dwarf::DW_LANG_Swift)
    return;
 
  if (!GlobalData.getOptions().ParseableSwiftInterfaces)
    return;
 
  StringRef Path =
      dwarf::toStringRef(find(DieEntry, dwarf::DW_AT_LLVM_include_path));
  if (!Path.ends_with(".swiftinterface"))
    return;
  // Don't track interfaces that are part of the SDK.
  StringRef SysRoot =
      dwarf::toStringRef(find(DieEntry, dwarf::DW_AT_LLVM_sysroot));
  if (SysRoot.empty())
    SysRoot = getSysRoot();
  if (!SysRoot.empty() && Path.starts_with(SysRoot))
    return;
  // Don't track interfaces that are part of the toolchain.
  // For example: Swift, _Concurrency, ...
  StringRef DeveloperDir = guessDeveloperDir(SysRoot);
  if (!DeveloperDir.empty() && Path.starts_with(DeveloperDir))
    return;
  if (isInToolchainDir(Path))
    return;
  if (std::optional<DWARFFormValue> Val = find(DieEntry, dwarf::DW_AT_name)) {
    Expected<const char *> Name = Val->getAsCString();
    if (!Name) {
      warn(Name.takeError());
      return;
    }
 
    // The prepend path is applied later when copying.
    SmallString<128> ResolvedPath;
    if (sys::path::is_relative(Path))
      sys::path::append(
          ResolvedPath,
          dwarf::toString(getUnitDIE().find(dwarf::DW_AT_comp_dir), ""));
    sys::path::append(ResolvedPath, Path);
 
    // Stage the entry. It will be merged into the shared
    // ParseableSwiftInterfaces map after the parallel analysis phase so that
    // the final contents and any conflict warnings are deterministic.
    PendingSwiftInterfaces.emplace_back(*Name, ResolvedPath);
  }
}
 
void CompileUnit::mergeSwiftInterfaces(
    DWARFLinkerBase::SwiftInterfacesMapTy &Map) {
  for (auto &Pending : PendingSwiftInterfaces) {
    auto &Entry = Map[Pending.ModuleName];
    if (!Entry.empty() && Entry != Pending.ResolvedPath)
      warn(Twine("conflicting parseable interfaces for Swift Module ") +
           Pending.ModuleName + ": " + Entry + " and " + Pending.ResolvedPath +
           ".");
    Entry = Pending.ResolvedPath;
  }
  PendingSwiftInterfaces.clear();
}
 
Error CompileUnit::assignTypeNames(TypePool &TypePoolRef) {
  if (!getUnitDIE().isValid())
    return Error::success();
 
  SyntheticTypeNameBuilder NameBuilder(TypePoolRef);
  return assignTypeNamesRec(getDebugInfoEntry(0), NameBuilder);
}
 
Error CompileUnit::assignTypeNamesRec(const DWARFDebugInfoEntry *DieEntry,
                                      SyntheticTypeNameBuilder &NameBuilder) {
  OrderedChildrenIndexAssigner ChildrenIndexAssigner(*this, DieEntry);
  for (const DWARFDebugInfoEntry *CurChild = getFirstChildEntry(DieEntry);
       CurChild && CurChild->getAbbreviationDeclarationPtr();
       CurChild = getSiblingEntry(CurChild)) {
    CompileUnit::DIEInfo &ChildInfo = getDIEInfo(CurChild);
    if (!ChildInfo.needToPlaceInTypeTable())
      continue;
 
    assert(ChildInfo.getODRAvailable());
    if (Error Err = NameBuilder.assignName(
            {this, CurChild},
            ChildrenIndexAssigner.getChildIndex(*this, CurChild)))
      return Err;
 
    if (Error Err = assignTypeNamesRec(CurChild, NameBuilder))
      return Err;
  }
 
  return Error::success();
}
 
void CompileUnit::updateDieRefPatchesWithClonedOffsets() {
  if (std::optional<SectionDescriptor *> DebugInfoSection =
          tryGetSectionDescriptor(DebugSectionKind::DebugInfo)) {
 
    (*DebugInfoSection)
        ->ListDebugDieRefPatch.forEach([&](DebugDieRefPatch &Patch) {
          /// Replace stored DIE indexes with DIE output offsets.
          Patch.RefDieIdxOrClonedOffset =
              Patch.RefCU.getPointer()->getDieOutOffset(
                  Patch.RefDieIdxOrClonedOffset);
        });
 
    (*DebugInfoSection)
        ->ListDebugULEB128DieRefPatch.forEach(
            [&](DebugULEB128DieRefPatch &Patch) {
              /// Replace stored DIE indexes with DIE output offsets.
              Patch.RefDieIdxOrClonedOffset =
                  Patch.RefCU.getPointer()->getDieOutOffset(
                      Patch.RefDieIdxOrClonedOffset);
            });
 
    (*DebugInfoSection)
        ->ListDebugDieModuleRefPatch.forEach(
            [&](DebugDieModuleRefPatch &Patch) {
              /// Replace stored DIE indexes with DIE output offsets.
              Patch.RefDieIdxOrClonedOffset =
                  Patch.RefCU.getPointer()->getDieOutOffset(
                      Patch.RefDieIdxOrClonedOffset);
            });
  }
 
  if (std::optional<SectionDescriptor *> DebugLocSection =
          tryGetSectionDescriptor(DebugSectionKind::DebugLoc)) {
    (*DebugLocSection)
        ->ListDebugULEB128DieRefPatch.forEach(
            [](DebugULEB128DieRefPatch &Patch) {
              /// Replace stored DIE indexes with DIE output offsets.
              Patch.RefDieIdxOrClonedOffset =
                  Patch.RefCU.getPointer()->getDieOutOffset(
                      Patch.RefDieIdxOrClonedOffset);
            });
  }
 
  if (std::optional<SectionDescriptor *> DebugLocListsSection =
          tryGetSectionDescriptor(DebugSectionKind::DebugLocLists)) {
    (*DebugLocListsSection)
        ->ListDebugULEB128DieRefPatch.forEach(
            [](DebugULEB128DieRefPatch &Patch) {
              /// Replace stored DIE indexes with DIE output offsets.
              Patch.RefDieIdxOrClonedOffset =
                  Patch.RefCU.getPointer()->getDieOutOffset(
                      Patch.RefDieIdxOrClonedOffset);
            });
  }
}
 
std::optional<UnitEntryPairTy> CompileUnit::resolveDIEReference(
    const DWARFFormValue &RefValue,
    ResolveInterCUReferencesMode CanResolveInterCUReferences) {
  CompileUnit *RefCU;
  uint64_t RefDIEOffset;
  if (std::optional<uint64_t> Offset = RefValue.getAsRelativeReference()) {
    RefCU = this;
    RefDIEOffset = RefValue.getUnit()->getOffset() + *Offset;
  } else if (Offset = RefValue.getAsDebugInfoReference(); Offset) {
    RefCU = getUnitFromOffset(*Offset);
    RefDIEOffset = *Offset;
  } else {
    return std::nullopt;
  }
 
  if (RefCU == this) {
    // Referenced DIE is in current compile unit.
    if (std::optional<uint32_t> RefDieIdx =
            getDIEIndexForOffset(RefDIEOffset)) {
      const DWARFDebugInfoEntry *RefEntry = getDebugInfoEntry(*RefDieIdx);
      // In a file with broken references, an attribute might point to a
      // NULL DIE. Treat that as a resolution failure so callers can warn.
      if (RefEntry && RefEntry->getAbbreviationDeclarationPtr())
        return UnitEntryPairTy{this, RefEntry};
    }
  } else if (RefCU && CanResolveInterCUReferences) {
    // Referenced DIE is in other compile unit.
 
    // Check whether DIEs are loaded for that compile unit.
    enum Stage ReferredCUStage = RefCU->getStage();
    if (ReferredCUStage < Stage::Loaded || ReferredCUStage > Stage::Cloned)
      return UnitEntryPairTy{RefCU, nullptr};
 
    if (std::optional<uint32_t> RefDieIdx =
            RefCU->getDIEIndexForOffset(RefDIEOffset)) {
      const DWARFDebugInfoEntry *RefEntry =
          RefCU->getDebugInfoEntry(*RefDieIdx);
      if (RefEntry && RefEntry->getAbbreviationDeclarationPtr())
        return UnitEntryPairTy{RefCU, RefEntry};
    }
  } else {
    return UnitEntryPairTy{RefCU, nullptr};
  }
  return std::nullopt;
}
 
std::optional<UnitEntryPairTy> CompileUnit::resolveDIEReference(
    const DWARFDebugInfoEntry *DieEntry, dwarf::Attribute Attr,
    ResolveInterCUReferencesMode CanResolveInterCUReferences) {
  if (std::optional<DWARFFormValue> AttrVal = find(DieEntry, Attr))
    return resolveDIEReference(*AttrVal, CanResolveInterCUReferences);
 
  return std::nullopt;
}
 
void CompileUnit::addFunctionRange(uint64_t FuncLowPc, uint64_t FuncHighPc,
                                   int64_t PcOffset) {
  std::lock_guard<std::mutex> Guard(RangesMutex);
 
  Ranges.insert({FuncLowPc, FuncHighPc}, PcOffset);
  if (LowPc)
    LowPc = std::min(*LowPc, FuncLowPc + PcOffset);
  else
    LowPc = FuncLowPc + PcOffset;
  this->HighPc = std::max(HighPc, FuncHighPc + PcOffset);
}
 
void CompileUnit::addLabelLowPc(uint64_t LabelLowPc, int64_t PcOffset) {
  std::lock_guard<std::mutex> Guard(LabelsMutex);
  Labels.insert({LabelLowPc, PcOffset});
}
 
Error CompileUnit::cloneAndEmitDebugLocations() {
  if (getGlobalData().getOptions().UpdateIndexTablesOnly)
    return Error::success();
 
  if (getOrigUnit().getVersion() < 5) {
    emitLocations(DebugSectionKind::DebugLoc);
    return Error::success();
  }
 
  emitLocations(DebugSectionKind::DebugLocLists);
  return Error::success();
}
 
void CompileUnit::emitLocations(DebugSectionKind LocationSectionKind) {
  SectionDescriptor &DebugInfoSection =
      getOrCreateSectionDescriptor(DebugSectionKind::DebugInfo);
 
  if (!DebugInfoSection.ListDebugLocPatch.empty()) {
    SectionDescriptor &OutLocationSection =
        getOrCreateSectionDescriptor(LocationSectionKind);
    DWARFUnit &OrigUnit = getOrigUnit();
 
    uint64_t OffsetAfterUnitLength = emitLocListHeader(OutLocationSection);
 
    DebugInfoSection.ListDebugLocPatch.forEach([&](DebugLocPatch &Patch) {
      // Get location expressions vector corresponding to the current
      // attribute from the source DWARF.
      uint64_t InputDebugLocSectionOffset = DebugInfoSection.getIntVal(
          Patch.PatchOffset,
          DebugInfoSection.getFormParams().getDwarfOffsetByteSize());
      Expected<DWARFLocationExpressionsVector> OriginalLocations =
          OrigUnit.findLoclistFromOffset(InputDebugLocSectionOffset);
 
      if (!OriginalLocations) {
        warn(OriginalLocations.takeError());
        return;
      }
 
      LinkedLocationExpressionsVector LinkedLocationExpressions;
      for (DWARFLocationExpression &CurExpression : *OriginalLocations) {
        LinkedLocationExpressionsWithOffsetPatches LinkedExpression;
 
        if (CurExpression.Range) {
          // Relocate address range.
          LinkedExpression.Expression.Range = {
              CurExpression.Range->LowPC + Patch.AddrAdjustmentValue,
              CurExpression.Range->HighPC + Patch.AddrAdjustmentValue};
        }
 
        DataExtractor Data(CurExpression.Expr, OrigUnit.isLittleEndian());
 
        DWARFExpression InputExpression(Data, OrigUnit.getAddressByteSize(),
                                        OrigUnit.getFormParams().Format);
        cloneDieAttrExpression(InputExpression,
                               LinkedExpression.Expression.Expr,
                               OutLocationSection, Patch.AddrAdjustmentValue,
                               LinkedExpression.Patches);
 
        LinkedLocationExpressions.push_back({LinkedExpression});
      }
 
      // Emit locations list table fragment corresponding to the CurLocAttr.
      DebugInfoSection.apply(Patch.PatchOffset, dwarf::DW_FORM_sec_offset,
                             OutLocationSection.OS.tell());
      emitLocListFragment(LinkedLocationExpressions, OutLocationSection);
    });
 
    if (OffsetAfterUnitLength > 0) {
      assert(OffsetAfterUnitLength -
                 OutLocationSection.getFormParams().getDwarfOffsetByteSize() <
             OffsetAfterUnitLength);
      OutLocationSection.apply(
          OffsetAfterUnitLength -
              OutLocationSection.getFormParams().getDwarfOffsetByteSize(),
          dwarf::DW_FORM_sec_offset,
          OutLocationSection.OS.tell() - OffsetAfterUnitLength);
    }
  }
}
 
/// Emit debug locations(.debug_loc, .debug_loclists) header.
uint64_t CompileUnit::emitLocListHeader(SectionDescriptor &OutLocationSection) {
  if (getOrigUnit().getVersion() < 5)
    return 0;
 
  // unit_length.
  OutLocationSection.emitUnitLength(0xBADDEF);
  uint64_t OffsetAfterUnitLength = OutLocationSection.OS.tell();
 
  // Version.
  OutLocationSection.emitIntVal(5, 2);
 
  // Address size.
  OutLocationSection.emitIntVal(OutLocationSection.getFormParams().AddrSize, 1);
 
  // Seg_size
  OutLocationSection.emitIntVal(0, 1);
 
  // Offset entry count
  OutLocationSection.emitIntVal(0, 4);
 
  return OffsetAfterUnitLength;
}
 
/// Emit debug locations(.debug_loc, .debug_loclists) fragment.
uint64_t CompileUnit::emitLocListFragment(
    const LinkedLocationExpressionsVector &LinkedLocationExpression,
    SectionDescriptor &OutLocationSection) {
  uint64_t OffsetBeforeLocationExpression = 0;
 
  if (getOrigUnit().getVersion() < 5) {
    uint64_t BaseAddress = 0;
    if (std::optional<uint64_t> LowPC = getLowPc())
      BaseAddress = *LowPC;
 
    for (const LinkedLocationExpressionsWithOffsetPatches &LocExpression :
         LinkedLocationExpression) {
      if (LocExpression.Expression.Range) {
        OutLocationSection.emitIntVal(
            LocExpression.Expression.Range->LowPC - BaseAddress,
            OutLocationSection.getFormParams().AddrSize);
        OutLocationSection.emitIntVal(
            LocExpression.Expression.Range->HighPC - BaseAddress,
            OutLocationSection.getFormParams().AddrSize);
      }
 
      OutLocationSection.emitIntVal(LocExpression.Expression.Expr.size(), 2);
      OffsetBeforeLocationExpression = OutLocationSection.OS.tell();
      for (uint64_t *OffsetPtr : LocExpression.Patches)
        *OffsetPtr += OffsetBeforeLocationExpression;
 
      OutLocationSection.OS
          << StringRef((const char *)LocExpression.Expression.Expr.data(),
                       LocExpression.Expression.Expr.size());
    }
 
    // Emit the terminator entry.
    OutLocationSection.emitIntVal(0,
                                  OutLocationSection.getFormParams().AddrSize);
    OutLocationSection.emitIntVal(0,
                                  OutLocationSection.getFormParams().AddrSize);
    return OffsetBeforeLocationExpression;
  }
 
  std::optional<uint64_t> BaseAddress;
  for (const LinkedLocationExpressionsWithOffsetPatches &LocExpression :
       LinkedLocationExpression) {
    if (LocExpression.Expression.Range) {
      // Check whether base address is set. If it is not set yet
      // then set current base address and emit base address selection entry.
      if (!BaseAddress) {
        BaseAddress = LocExpression.Expression.Range->LowPC;
 
        // Emit base address.
        OutLocationSection.emitIntVal(dwarf::DW_LLE_base_addressx, 1);
        encodeULEB128(DebugAddrIndexMap.getValueIndex(*BaseAddress),
                      OutLocationSection.OS);
      }
 
      // Emit type of entry.
      OutLocationSection.emitIntVal(dwarf::DW_LLE_offset_pair, 1);
 
      // Emit start offset relative to base address.
      encodeULEB128(LocExpression.Expression.Range->LowPC - *BaseAddress,
                    OutLocationSection.OS);
 
      // Emit end offset relative to base address.
      encodeULEB128(LocExpression.Expression.Range->HighPC - *BaseAddress,
                    OutLocationSection.OS);
    } else
      // Emit type of entry.
      OutLocationSection.emitIntVal(dwarf::DW_LLE_default_location, 1);
 
    encodeULEB128(LocExpression.Expression.Expr.size(), OutLocationSection.OS);
    OffsetBeforeLocationExpression = OutLocationSection.OS.tell();
    for (uint64_t *OffsetPtr : LocExpression.Patches)
      *OffsetPtr += OffsetBeforeLocationExpression;
 
    OutLocationSection.OS << StringRef(
        (const char *)LocExpression.Expression.Expr.data(),
        LocExpression.Expression.Expr.size());
  }
 
  // Emit the terminator entry.
  OutLocationSection.emitIntVal(dwarf::DW_LLE_end_of_list, 1);
  return OffsetBeforeLocationExpression;
}
 
Error CompileUnit::emitDebugAddrSection() {
  if (GlobalData.getOptions().UpdateIndexTablesOnly)
    return Error::success();
 
  if (getVersion() < 5)
    return Error::success();
 
  if (DebugAddrIndexMap.empty())
    return Error::success();
 
  SectionDescriptor &OutAddrSection =
      getOrCreateSectionDescriptor(DebugSectionKind::DebugAddr);
 
  // Emit section header.
 
  //   Emit length.
  OutAddrSection.emitUnitLength(0xBADDEF);
  uint64_t OffsetAfterSectionLength = OutAddrSection.OS.tell();
 
  //   Emit version.
  OutAddrSection.emitIntVal(5, 2);
 
  //   Emit address size.
  OutAddrSection.emitIntVal(getFormParams().AddrSize, 1);
 
  //   Emit segment size.
  OutAddrSection.emitIntVal(0, 1);
 
  // Emit addresses.
  for (uint64_t AddrValue : DebugAddrIndexMap.getValues())
    OutAddrSection.emitIntVal(AddrValue, getFormParams().AddrSize);
 
  // Patch section length.
  OutAddrSection.apply(
      OffsetAfterSectionLength -
          OutAddrSection.getFormParams().getDwarfOffsetByteSize(),
      dwarf::DW_FORM_sec_offset,
      OutAddrSection.OS.tell() - OffsetAfterSectionLength);
 
  return Error::success();
}
 
Error CompileUnit::cloneAndEmitRanges() {
  if (getGlobalData().getOptions().UpdateIndexTablesOnly)
    return Error::success();
 
  // Build set of linked address ranges for unit function ranges.
  AddressRanges LinkedFunctionRanges;
  for (const AddressRangeValuePair &Range : getFunctionRanges())
    LinkedFunctionRanges.insert(
        {Range.Range.start() + Range.Value, Range.Range.end() + Range.Value});
 
  emitAranges(LinkedFunctionRanges);
 
  if (getOrigUnit().getVersion() < 5) {
    cloneAndEmitRangeList(DebugSectionKind::DebugRange, LinkedFunctionRanges);
    return Error::success();
  }
 
  cloneAndEmitRangeList(DebugSectionKind::DebugRngLists, LinkedFunctionRanges);
  return Error::success();
}
 
void CompileUnit::cloneAndEmitRangeList(DebugSectionKind RngSectionKind,
                                        AddressRanges &LinkedFunctionRanges) {
  SectionDescriptor &DebugInfoSection =
      getOrCreateSectionDescriptor(DebugSectionKind::DebugInfo);
  SectionDescriptor &OutRangeSection =
      getOrCreateSectionDescriptor(RngSectionKind);
 
  if (!DebugInfoSection.ListDebugRangePatch.empty()) {
    std::optional<AddressRangeValuePair> CachedRange;
    uint64_t OffsetAfterUnitLength = emitRangeListHeader(OutRangeSection);
 
    DebugRangePatch *CompileUnitRangePtr = nullptr;
    DebugInfoSection.ListDebugRangePatch.forEach([&](DebugRangePatch &Patch) {
      if (Patch.IsCompileUnitRanges) {
        CompileUnitRangePtr = &Patch;
      } else {
        // Get ranges from the source DWARF corresponding to the current
        // attribute.
        AddressRanges LinkedRanges;
        uint64_t InputDebugRangesSectionOffset = DebugInfoSection.getIntVal(
            Patch.PatchOffset,
            DebugInfoSection.getFormParams().getDwarfOffsetByteSize());
        if (Expected<DWARFAddressRangesVector> InputRanges =
                getOrigUnit().findRnglistFromOffset(
                    InputDebugRangesSectionOffset)) {
          // Apply relocation adjustment.
          for (const auto &Range : *InputRanges) {
            if (!CachedRange || !CachedRange->Range.contains(Range.LowPC))
              CachedRange =
                  getFunctionRanges().getRangeThatContains(Range.LowPC);
 
            // All range entries should lie in the function range.
            if (!CachedRange) {
              warn("inconsistent range data.");
              continue;
            }
 
            // Store range for emiting.
            LinkedRanges.insert({Range.LowPC + CachedRange->Value,
                                 Range.HighPC + CachedRange->Value});
          }
        } else {
          llvm::consumeError(InputRanges.takeError());
          warn("invalid range list ignored.");
        }
 
        // Emit linked ranges.
        DebugInfoSection.apply(Patch.PatchOffset, dwarf::DW_FORM_sec_offset,
                               OutRangeSection.OS.tell());
        emitRangeListFragment(LinkedRanges, OutRangeSection);
      }
    });
 
    if (CompileUnitRangePtr != nullptr) {
      // Emit compile unit ranges last to be binary compatible with classic
      // dsymutil.
      DebugInfoSection.apply(CompileUnitRangePtr->PatchOffset,
                             dwarf::DW_FORM_sec_offset,
                             OutRangeSection.OS.tell());
      emitRangeListFragment(LinkedFunctionRanges, OutRangeSection);
    }
 
    if (OffsetAfterUnitLength > 0) {
      assert(OffsetAfterUnitLength -
                 OutRangeSection.getFormParams().getDwarfOffsetByteSize() <
             OffsetAfterUnitLength);
      OutRangeSection.apply(
          OffsetAfterUnitLength -
              OutRangeSection.getFormParams().getDwarfOffsetByteSize(),
          dwarf::DW_FORM_sec_offset,
          OutRangeSection.OS.tell() - OffsetAfterUnitLength);
    }
  }
}
 
uint64_t CompileUnit::emitRangeListHeader(SectionDescriptor &OutRangeSection) {
  if (OutRangeSection.getFormParams().Version < 5)
    return 0;
 
  // unit_length.
  OutRangeSection.emitUnitLength(0xBADDEF);
  uint64_t OffsetAfterUnitLength = OutRangeSection.OS.tell();
 
  // Version.
  OutRangeSection.emitIntVal(5, 2);
 
  // Address size.
  OutRangeSection.emitIntVal(OutRangeSection.getFormParams().AddrSize, 1);
 
  // Seg_size
  OutRangeSection.emitIntVal(0, 1);
 
  // Offset entry count
  OutRangeSection.emitIntVal(0, 4);
 
  return OffsetAfterUnitLength;
}
 
void CompileUnit::emitRangeListFragment(const AddressRanges &LinkedRanges,
                                        SectionDescriptor &OutRangeSection) {
  if (OutRangeSection.getFormParams().Version < 5) {
    // Emit ranges.
    uint64_t BaseAddress = 0;
    if (std::optional<uint64_t> LowPC = getLowPc())
      BaseAddress = *LowPC;
 
    for (const AddressRange &Range : LinkedRanges) {
      OutRangeSection.emitIntVal(Range.start() - BaseAddress,
                                 OutRangeSection.getFormParams().AddrSize);
      OutRangeSection.emitIntVal(Range.end() - BaseAddress,
                                 OutRangeSection.getFormParams().AddrSize);
    }
 
    // Add the terminator entry.
    OutRangeSection.emitIntVal(0, OutRangeSection.getFormParams().AddrSize);
    OutRangeSection.emitIntVal(0, OutRangeSection.getFormParams().AddrSize);
    return;
  }
 
  std::optional<uint64_t> BaseAddress;
  for (const AddressRange &Range : LinkedRanges) {
    if (!BaseAddress) {
      BaseAddress = Range.start();
 
      // Emit base address.
      OutRangeSection.emitIntVal(dwarf::DW_RLE_base_addressx, 1);
      encodeULEB128(getDebugAddrIndex(*BaseAddress), OutRangeSection.OS);
    }
 
    // Emit type of entry.
    OutRangeSection.emitIntVal(dwarf::DW_RLE_offset_pair, 1);
 
    // Emit start offset relative to base address.
    encodeULEB128(Range.start() - *BaseAddress, OutRangeSection.OS);
 
    // Emit end offset relative to base address.
    encodeULEB128(Range.end() - *BaseAddress, OutRangeSection.OS);
  }
 
  // Emit the terminator entry.
  OutRangeSection.emitIntVal(dwarf::DW_RLE_end_of_list, 1);
}
 
void CompileUnit::emitAranges(AddressRanges &LinkedFunctionRanges) {
  if (LinkedFunctionRanges.empty())
    return;
 
  SectionDescriptor &DebugInfoSection =
      getOrCreateSectionDescriptor(DebugSectionKind::DebugInfo);
  SectionDescriptor &OutArangesSection =
      getOrCreateSectionDescriptor(DebugSectionKind::DebugARanges);
 
  // Emit Header.
  unsigned HeaderSize =
      sizeof(int32_t) + // Size of contents (w/o this field
      sizeof(int16_t) + // DWARF ARange version number
      sizeof(int32_t) + // Offset of CU in the .debug_info section
      sizeof(int8_t) +  // Pointer Size (in bytes)
      sizeof(int8_t);   // Segment Size (in bytes)
 
  unsigned TupleSize = OutArangesSection.getFormParams().AddrSize * 2;
  unsigned Padding = offsetToAlignment(HeaderSize, Align(TupleSize));
 
  OutArangesSection.emitOffset(0xBADDEF); // Aranges length
  uint64_t OffsetAfterArangesLengthField = OutArangesSection.OS.tell();
 
  OutArangesSection.emitIntVal(dwarf::DW_ARANGES_VERSION, 2); // Version number
  OutArangesSection.notePatch(
      DebugOffsetPatch{OutArangesSection.OS.tell(), &DebugInfoSection});
  OutArangesSection.emitOffset(0xBADDEF); // Corresponding unit's offset
  OutArangesSection.emitIntVal(OutArangesSection.getFormParams().AddrSize,
                               1);    // Address size
  OutArangesSection.emitIntVal(0, 1); // Segment size
 
  for (size_t Idx = 0; Idx < Padding; Idx++)
    OutArangesSection.emitIntVal(0, 1); // Padding
 
  // Emit linked ranges.
  for (const AddressRange &Range : LinkedFunctionRanges) {
    OutArangesSection.emitIntVal(Range.start(),
                                 OutArangesSection.getFormParams().AddrSize);
    OutArangesSection.emitIntVal(Range.end() - Range.start(),
                                 OutArangesSection.getFormParams().AddrSize);
  }
 
  // Emit terminator.
  OutArangesSection.emitIntVal(0, OutArangesSection.getFormParams().AddrSize);
  OutArangesSection.emitIntVal(0, OutArangesSection.getFormParams().AddrSize);
 
  uint64_t OffsetAfterArangesEnd = OutArangesSection.OS.tell();
 
  // Update Aranges lentgh.
  OutArangesSection.apply(
      OffsetAfterArangesLengthField -
          OutArangesSection.getFormParams().getDwarfOffsetByteSize(),
      dwarf::DW_FORM_sec_offset,
      OffsetAfterArangesEnd - OffsetAfterArangesLengthField);
}
 
Error CompileUnit::cloneAndEmitDebugMacro() {
  if (getOutUnitDIE() == nullptr)
    return Error::success();
 
  DWARFUnit &OrigUnit = getOrigUnit();
  DWARFDie OrigUnitDie = OrigUnit.getUnitDIE();
 
  // Check for .debug_macro table.
  if (std::optional<uint64_t> MacroAttr =
          dwarf::toSectionOffset(OrigUnitDie.find(dwarf::DW_AT_macros))) {
    if (const DWARFDebugMacro *Table =
            getContainingFile().Dwarf->getDebugMacro()) {
      emitMacroTableImpl(Table, *MacroAttr, true);
    }
  }
 
  // Check for .debug_macinfo table.
  if (std::optional<uint64_t> MacroAttr =
          dwarf::toSectionOffset(OrigUnitDie.find(dwarf::DW_AT_macro_info))) {
    if (const DWARFDebugMacro *Table =
            getContainingFile().Dwarf->getDebugMacinfo()) {
      emitMacroTableImpl(Table, *MacroAttr, false);
    }
  }
 
  return Error::success();
}
 
void CompileUnit::emitMacroTableImpl(const DWARFDebugMacro *MacroTable,
                                     uint64_t OffsetToMacroTable,
                                     bool hasDWARFv5Header) {
  SectionDescriptor &OutSection =
      hasDWARFv5Header
          ? getOrCreateSectionDescriptor(DebugSectionKind::DebugMacro)
          : getOrCreateSectionDescriptor(DebugSectionKind::DebugMacinfo);
 
  bool DefAttributeIsReported = false;
  bool UndefAttributeIsReported = false;
  bool ImportAttributeIsReported = false;
 
  for (const DWARFDebugMacro::MacroList &List : MacroTable->MacroLists) {
    if (OffsetToMacroTable == List.Offset) {
      // Write DWARFv5 header.
      if (hasDWARFv5Header) {
        // Write header version.
        OutSection.emitIntVal(List.Header.Version, sizeof(List.Header.Version));
 
        uint8_t Flags = List.Header.Flags;
 
        // Check for OPCODE_OPERANDS_TABLE.
        if (Flags &
            DWARFDebugMacro::HeaderFlagMask::MACRO_OPCODE_OPERANDS_TABLE) {
          Flags &=
              ~DWARFDebugMacro::HeaderFlagMask::MACRO_OPCODE_OPERANDS_TABLE;
          warn("opcode_operands_table is not supported yet.");
        }
 
        // Check for DEBUG_LINE_OFFSET.
        std::optional<uint64_t> StmtListOffset;
        if (Flags & DWARFDebugMacro::HeaderFlagMask::MACRO_DEBUG_LINE_OFFSET) {
          // Get offset to the line table from the cloned compile unit.
          for (auto &V : getOutUnitDIE()->values()) {
            if (V.getAttribute() == dwarf::DW_AT_stmt_list) {
              StmtListOffset = V.getDIEInteger().getValue();
              break;
            }
          }
 
          if (!StmtListOffset) {
            Flags &= ~DWARFDebugMacro::HeaderFlagMask::MACRO_DEBUG_LINE_OFFSET;
            warn("couldn`t find line table for macro table.");
          }
        }
 
        // Write flags.
        OutSection.emitIntVal(Flags, sizeof(Flags));
 
        // Write offset to line table.
        if (StmtListOffset) {
          OutSection.notePatch(DebugOffsetPatch{
              OutSection.OS.tell(),
              &getOrCreateSectionDescriptor(DebugSectionKind::DebugLine)});
          // TODO: check that List.Header.getOffsetByteSize() and
          // DebugOffsetPatch agree on size.
          OutSection.emitIntVal(0xBADDEF, List.Header.getOffsetByteSize());
        }
      }
 
      // Write macro entries.
      for (const DWARFDebugMacro::Entry &MacroEntry : List.Macros) {
        if (MacroEntry.Type == 0) {
          encodeULEB128(MacroEntry.Type, OutSection.OS);
          continue;
        }
 
        uint8_t MacroType = MacroEntry.Type;
        switch (MacroType) {
        default: {
          bool HasVendorSpecificExtension =
              (!hasDWARFv5Header &&
               MacroType == dwarf::DW_MACINFO_vendor_ext) ||
              (hasDWARFv5Header && (MacroType >= dwarf::DW_MACRO_lo_user &&
                                    MacroType <= dwarf::DW_MACRO_hi_user));
 
          if (HasVendorSpecificExtension) {
            // Write macinfo type.
            OutSection.emitIntVal(MacroType, 1);
 
            // Write vendor extension constant.
            encodeULEB128(MacroEntry.ExtConstant, OutSection.OS);
 
            // Write vendor extension string.
            OutSection.emitString(dwarf::DW_FORM_string, MacroEntry.ExtStr);
          } else
            warn("unknown macro type. skip.");
        } break;
        // debug_macro and debug_macinfo share some common encodings.
        // DW_MACRO_define     == DW_MACINFO_define
        // DW_MACRO_undef      == DW_MACINFO_undef
        // DW_MACRO_start_file == DW_MACINFO_start_file
        // DW_MACRO_end_file   == DW_MACINFO_end_file
        // For readibility/uniformity we are using DW_MACRO_*.
        case dwarf::DW_MACRO_define:
        case dwarf::DW_MACRO_undef: {
          // Write macinfo type.
          OutSection.emitIntVal(MacroType, 1);
 
          // Write source line.
          encodeULEB128(MacroEntry.Line, OutSection.OS);
 
          // Write macro string.
          OutSection.emitString(dwarf::DW_FORM_string, MacroEntry.MacroStr);
        } break;
        case dwarf::DW_MACRO_define_strp:
        case dwarf::DW_MACRO_undef_strp:
        case dwarf::DW_MACRO_define_strx:
        case dwarf::DW_MACRO_undef_strx: {
          // DW_MACRO_*_strx forms are not supported currently.
          // Convert to *_strp.
          switch (MacroType) {
          case dwarf::DW_MACRO_define_strx: {
            MacroType = dwarf::DW_MACRO_define_strp;
            if (!DefAttributeIsReported) {
              warn("DW_MACRO_define_strx unsupported yet. Convert to "
                   "DW_MACRO_define_strp.");
              DefAttributeIsReported = true;
            }
          } break;
          case dwarf::DW_MACRO_undef_strx: {
            MacroType = dwarf::DW_MACRO_undef_strp;
            if (!UndefAttributeIsReported) {
              warn("DW_MACRO_undef_strx unsupported yet. Convert to "
                   "DW_MACRO_undef_strp.");
              UndefAttributeIsReported = true;
            }
          } break;
          default:
            // Nothing to do.
            break;
          }
 
          // Write macinfo type.
          OutSection.emitIntVal(MacroType, 1);
 
          // Write source line.
          encodeULEB128(MacroEntry.Line, OutSection.OS);
 
          // Write macro string.
          OutSection.emitString(dwarf::DW_FORM_strp, MacroEntry.MacroStr);
          break;
        }
        case dwarf::DW_MACRO_start_file: {
          // Write macinfo type.
          OutSection.emitIntVal(MacroType, 1);
          // Write source line.
          encodeULEB128(MacroEntry.Line, OutSection.OS);
          // Write source file id.
          encodeULEB128(MacroEntry.File, OutSection.OS);
        } break;
        case dwarf::DW_MACRO_end_file: {
          // Write macinfo type.
          OutSection.emitIntVal(MacroType, 1);
        } break;
        case dwarf::DW_MACRO_import:
        case dwarf::DW_MACRO_import_sup: {
          if (!ImportAttributeIsReported) {
            warn("DW_MACRO_import and DW_MACRO_import_sup are unsupported "
                 "yet. remove.");
            ImportAttributeIsReported = true;
          }
        } break;
        }
      }
 
      return;
    }
  }
}
 
void CompileUnit::cloneDieAttrExpression(
    const DWARFExpression &InputExpression,
    SmallVectorImpl<uint8_t> &OutputExpression, SectionDescriptor &Section,
    std::optional<int64_t> VarAddressAdjustment,
    OffsetsPtrVector &PatchesOffsets) {
  using Encoding = DWARFExpression::Operation::Encoding;
 
  DWARFUnit &OrigUnit = getOrigUnit();
  uint8_t OrigAddressByteSize = OrigUnit.getAddressByteSize();
 
  uint64_t OpOffset = 0;
  for (auto &Op : InputExpression) {
    if (Op.isError()) {
      // The operation could not be decoded, so neither it nor anything after
      // it can be located. Its end offset is the offset it started at, so the
      // slice copied below would be empty and the rest of the expression
      // would be silently dropped. Preserve the remaining bytes instead.
      warn("cannot decode a DW_OP, copying the rest of the expression "
           "unmodified.");
      StringRef Bytes = InputExpression.getData().substr(OpOffset);
      OutputExpression.append(Bytes.begin(), Bytes.end());
      return;
    }
    auto Desc = Op.getDescription();
    // DW_OP_const_type is variable-length and has 3
    // operands. Thus far we only support 2.
    if ((Desc.Op.size() == 2 && Desc.Op[0] == Encoding::BaseTypeRef) ||
        (Desc.Op.size() == 2 && Desc.Op[1] == Encoding::BaseTypeRef &&
         Desc.Op[0] != Encoding::Size1))
      warn("unsupported DW_OP encoding.");
 
    if ((Desc.Op.size() == 1 && Desc.Op[0] == Encoding::BaseTypeRef) ||
        (Desc.Op.size() == 2 && Desc.Op[1] == Encoding::BaseTypeRef &&
         Desc.Op[0] == Encoding::Size1)) {
      // This code assumes that the other non-typeref operand fits into 1 byte.
      assert(OpOffset < Op.getEndOffset());
      uint32_t ULEBsize = Op.getEndOffset() - OpOffset - 1;
      assert(ULEBsize <= 16);
 
      // Copy over the operation.
      assert(!Op.getSubCode() && "SubOps not yet supported");
      OutputExpression.push_back(Op.getCode());
      uint64_t RefOffset;
      if (Desc.Op.size() == 1) {
        RefOffset = Op.getRawOperand(0);
      } else {
        OutputExpression.push_back(Op.getRawOperand(0));
        RefOffset = Op.getRawOperand(1);
      }
      uint8_t ULEB[16];
      uint32_t Offset = 0;
      unsigned RealSize = 0;
      // Look up the base type. For DW_OP_convert, the operand may be 0 to
      // instead indicate the generic type. The same holds for
      // DW_OP_reinterpret, which is currently not supported.
      if (RefOffset > 0 || Op.getCode() != dwarf::DW_OP_convert) {
        RefOffset += OrigUnit.getOffset();
        uint32_t RefDieIdx = 0;
        if (std::optional<uint32_t> Idx =
                OrigUnit.getDIEIndexForOffset(RefOffset))
          RefDieIdx = *Idx;
 
        // Use fixed size for ULEB128 data, since we need to update that size
        // later with the proper offsets. Use 5 for DWARF32, 9 for DWARF64.
        ULEBsize = getFormParams().getDwarfOffsetByteSize() + 1;
 
        RealSize = encodeULEB128(0xBADDEF, ULEB, ULEBsize);
 
        Section.notePatchWithOffsetUpdate(
            DebugULEB128DieRefPatch(OutputExpression.size(), this, this,
                                    RefDieIdx),
            PatchesOffsets);
      } else
        RealSize = encodeULEB128(Offset, ULEB, ULEBsize);
 
      if (RealSize > ULEBsize) {
        // Emit the generic type as a fallback.
        RealSize = encodeULEB128(0, ULEB, ULEBsize);
        warn("base type ref doesn't fit.");
      }
      assert(RealSize == ULEBsize && "padding failed");
      ArrayRef<uint8_t> ULEBbytes(ULEB, ULEBsize);
      OutputExpression.append(ULEBbytes.begin(), ULEBbytes.end());
    } else if (!getGlobalData().getOptions().UpdateIndexTablesOnly &&
               Op.getCode() == dwarf::DW_OP_addrx) {
      if (std::optional<object::SectionedAddress> SA =
              OrigUnit.getAddrOffsetSectionItem(Op.getRawOperand(0))) {
        // DWARFLinker does not use addrx forms since it generates relocated
        // addresses. Replace DW_OP_addrx with DW_OP_addr here.
        // Argument of DW_OP_addrx should be relocated here as it is not
        // processed by applyValidRelocs.
        OutputExpression.push_back(dwarf::DW_OP_addr);
        uint64_t LinkedAddress =
            SA->Address +
            getContainingFile()
                .Addresses->getAddrIndexRelocAdjustment(OrigUnit, Op, false)
                .value_or(VarAddressAdjustment.value_or(0));
        if (getEndianness() != llvm::endianness::native)
          sys::swapByteOrder(LinkedAddress);
        ArrayRef<uint8_t> AddressBytes(
            reinterpret_cast<const uint8_t *>(&LinkedAddress),
            OrigAddressByteSize);
        OutputExpression.append(AddressBytes.begin(), AddressBytes.end());
      } else
        warn("cann't read DW_OP_addrx operand.");
    } else if (!getGlobalData().getOptions().UpdateIndexTablesOnly &&
               Op.getCode() == dwarf::DW_OP_constx) {
      if (std::optional<object::SectionedAddress> SA =
              OrigUnit.getAddrOffsetSectionItem(Op.getRawOperand(0))) {
        // DWARFLinker does not use constx forms since it generates relocated
        // addresses. Replace DW_OP_constx with DW_OP_const[*]u here.
        // Argument of DW_OP_constx should be relocated here as it is not
        // processed by applyValidRelocs.
        std::optional<uint8_t> OutOperandKind;
        switch (OrigAddressByteSize) {
        case 2:
          OutOperandKind = dwarf::DW_OP_const2u;
          break;
        case 4:
          OutOperandKind = dwarf::DW_OP_const4u;
          break;
        case 8:
          OutOperandKind = dwarf::DW_OP_const8u;
          break;
        default:
          warn(
              formatv(("unsupported address size: {0}."), OrigAddressByteSize));
          break;
        }
 
        if (OutOperandKind) {
          OutputExpression.push_back(*OutOperandKind);
          uint64_t LinkedAddress =
              SA->Address +
              getContainingFile()
                  .Addresses->getAddrIndexRelocAdjustment(OrigUnit, Op, false)
                  .value_or(VarAddressAdjustment.value_or(0));
          if (getEndianness() != llvm::endianness::native)
            sys::swapByteOrder(LinkedAddress);
          ArrayRef<uint8_t> AddressBytes(
              reinterpret_cast<const uint8_t *>(&LinkedAddress),
              OrigAddressByteSize);
          OutputExpression.append(AddressBytes.begin(), AddressBytes.end());
        }
      } else
        warn("cann't read DW_OP_constx operand.");
    } else {
      // Copy over everything else unmodified.
      StringRef Bytes =
          InputExpression.getData().slice(OpOffset, Op.getEndOffset());
      OutputExpression.append(Bytes.begin(), Bytes.end());
    }
    OpOffset = Op.getEndOffset();
  }
}
 
Error CompileUnit::cloneAndEmit(
    std::optional<std::reference_wrapper<const Triple>> TargetTriple,
    TypeUnit *ArtificialTypeUnit) {
  BumpPtrAllocator Allocator;
 
  DWARFDie OrigUnitDIE = getOrigUnit().getUnitDIE();
  if (!OrigUnitDIE.isValid())
    return Error::success();
 
  TypeEntry *RootEntry = nullptr;
  if (ArtificialTypeUnit)
    RootEntry = ArtificialTypeUnit->getTypePool().getRoot();
 
  // Clone input DIE entry recursively.
  std::pair<DIE *, TypeEntry *> OutCUDie = cloneDIE(
      OrigUnitDIE.getDebugInfoEntry(), RootEntry, getDebugInfoHeaderSize(),
      std::nullopt, std::nullopt, Allocator, ArtificialTypeUnit);
  setOutUnitDIE(OutCUDie.first);
 
  if (!TargetTriple.has_value() || (OutCUDie.first == nullptr))
    return Error::success();
 
  if (Error Err = cloneAndEmitLineTable((*TargetTriple).get()))
    return Err;
 
  if (Error Err = cloneAndEmitDebugMacro())
    return Err;
 
  getOrCreateSectionDescriptor(DebugSectionKind::DebugInfo);
  if (Error Err = emitDebugInfo((*TargetTriple).get()))
    return Err;
 
  // ASSUMPTION: .debug_info section should already be emitted at this point.
  // cloneAndEmitRanges & cloneAndEmitDebugLocations use .debug_info section
  // data.
 
  if (Error Err = cloneAndEmitRanges())
    return Err;
 
  if (Error Err = cloneAndEmitDebugLocations())
    return Err;
 
  if (Error Err = emitDebugAddrSection())
    return Err;
 
  // Generate Pub accelerator tables.
  if (llvm::is_contained(GlobalData.getOptions().AccelTables,
                         DWARFLinker::AccelTableKind::Pub))
    emitPubAccelerators();
 
  if (Error Err = emitDebugStringOffsetSection())
    return Err;
 
  return emitAbbreviations();
}
 
std::pair<DIE *, TypeEntry *> CompileUnit::cloneDIE(
    const DWARFDebugInfoEntry *InputDieEntry, TypeEntry *ClonedParentTypeDIE,
    uint64_t OutOffset, std::optional<int64_t> FuncAddressAdjustment,
    std::optional<int64_t> VarAddressAdjustment, BumpPtrAllocator &Allocator,
    TypeUnit *ArtificialTypeUnit, uint32_t SiblingOrdinal) {
  uint32_t InputDieIdx = getDIEIndex(InputDieEntry);
  CompileUnit::DIEInfo &Info = getDIEInfo(InputDieIdx);
 
  bool NeedToClonePlainDIE = Info.needToKeepInPlainDwarf();
  bool NeedToCloneTypeDIE =
      (InputDieEntry->getTag() != dwarf::DW_TAG_compile_unit) &&
      Info.needToPlaceInTypeTable();
  std::pair<DIE *, TypeEntry *> ClonedDIE;
 
  DIEGenerator PlainDIEGenerator(Allocator, *this);
 
  if (NeedToClonePlainDIE)
    // Create a cloned DIE which would be placed into the cloned version
    // of input compile unit.
    ClonedDIE.first = createPlainDIEandCloneAttributes(
        InputDieEntry, PlainDIEGenerator, OutOffset, FuncAddressAdjustment,
        VarAddressAdjustment);
  if (NeedToCloneTypeDIE) {
    // Create a cloned DIE which would be placed into the artificial type
    // unit.
    assert(ArtificialTypeUnit != nullptr);
    DIEGenerator TypeDIEGenerator(
        ArtificialTypeUnit->getTypePool().getThreadLocalAllocator(), *this);
 
    ClonedDIE.second = createTypeDIEandCloneAttributes(
        InputDieEntry, TypeDIEGenerator, ClonedParentTypeDIE,
        ArtificialTypeUnit, SiblingOrdinal);
  }
  TypeEntry *TypeParentForChild =
      ClonedDIE.second ? ClonedDIE.second : ClonedParentTypeDIE;
 
  bool HasPlainChildrenToClone =
      (ClonedDIE.first && Info.getKeepPlainChildren());
 
  bool HasTypeChildrenToClone =
      ((ClonedDIE.second ||
        InputDieEntry->getTag() == dwarf::DW_TAG_compile_unit) &&
       Info.getKeepTypeChildren());
 
  // Recursively clone children.
  if (HasPlainChildrenToClone || HasTypeChildrenToClone) {
    uint32_t ChildOrdinal = 0;
    for (const DWARFDebugInfoEntry *CurChild =
             getFirstChildEntry(InputDieEntry);
         CurChild && CurChild->getAbbreviationDeclarationPtr();
         CurChild = getSiblingEntry(CurChild), ++ChildOrdinal) {
      std::pair<DIE *, TypeEntry *> ClonedChild = cloneDIE(
          CurChild, TypeParentForChild, OutOffset, FuncAddressAdjustment,
          VarAddressAdjustment, Allocator, ArtificialTypeUnit, ChildOrdinal);
 
      if (ClonedChild.first) {
        OutOffset =
            ClonedChild.first->getOffset() + ClonedChild.first->getSize();
        PlainDIEGenerator.addChild(ClonedChild.first);
      }
    }
    assert(ClonedDIE.first == nullptr ||
           HasPlainChildrenToClone == ClonedDIE.first->hasChildren());
 
    // Account for the end of children marker.
    if (HasPlainChildrenToClone)
      OutOffset += sizeof(int8_t);
  }
 
  // Update our size.
  if (ClonedDIE.first != nullptr)
    ClonedDIE.first->setSize(OutOffset - ClonedDIE.first->getOffset());
 
  return ClonedDIE;
}
 
DIE *CompileUnit::createPlainDIEandCloneAttributes(
    const DWARFDebugInfoEntry *InputDieEntry, DIEGenerator &PlainDIEGenerator,
    uint64_t &OutOffset, std::optional<int64_t> &FuncAddressAdjustment,
    std::optional<int64_t> &VarAddressAdjustment) {
  uint32_t InputDieIdx = getDIEIndex(InputDieEntry);
  CompileUnit::DIEInfo &Info = getDIEInfo(InputDieIdx);
  DIE *ClonedDIE = nullptr;
  bool HasLocationExpressionAddress = false;
  if (InputDieEntry->getTag() == dwarf::DW_TAG_subprogram) {
    // Get relocation adjustment value for the current function.
    FuncAddressAdjustment =
        getContainingFile().Addresses->getSubprogramRelocAdjustment(
            getDIE(InputDieEntry), false);
  } else if (InputDieEntry->getTag() == dwarf::DW_TAG_label) {
    // Get relocation adjustment value for the current label.
    std::optional<uint64_t> lowPC =
        dwarf::toAddress(find(InputDieEntry, dwarf::DW_AT_low_pc));
    if (lowPC) {
      LabelMapTy::iterator It = Labels.find(*lowPC);
      if (It != Labels.end())
        FuncAddressAdjustment = It->second;
    }
  } else if (InputDieEntry->getTag() == dwarf::DW_TAG_variable) {
    // Get relocation adjustment value for the current variable.
    std::pair<bool, std::optional<int64_t>> LocExprAddrAndRelocAdjustment =
        getContainingFile().Addresses->getVariableRelocAdjustment(
            getDIE(InputDieEntry), false);
 
    HasLocationExpressionAddress = LocExprAddrAndRelocAdjustment.first;
    if (LocExprAddrAndRelocAdjustment.first &&
        LocExprAddrAndRelocAdjustment.second)
      VarAddressAdjustment = *LocExprAddrAndRelocAdjustment.second;
  }
 
  ClonedDIE = PlainDIEGenerator.createDIE(InputDieEntry->getTag(), OutOffset);
 
  // Offset to the DIE would be used after output DIE tree is deleted.
  // Thus we need to remember DIE offset separately.
  rememberDieOutOffset(InputDieIdx, OutOffset);
 
  // Clone Attributes.
  DIEAttributeCloner AttributesCloner(ClonedDIE, *this, this, InputDieEntry,
                                      PlainDIEGenerator, FuncAddressAdjustment,
                                      VarAddressAdjustment,
                                      HasLocationExpressionAddress);
  AttributesCloner.clone();
 
  // Remember accelerator info.
  AcceleratorRecordsSaver AccelRecordsSaver(getGlobalData(), *this, this);
  AccelRecordsSaver.save(InputDieEntry, ClonedDIE, AttributesCloner.AttrInfo,
                         nullptr);
 
  OutOffset =
      AttributesCloner.finalizeAbbreviations(Info.getKeepPlainChildren());
 
  return ClonedDIE;
}
 
/// Allocates output DIE for the specified \p TypeDescriptor.
DIE *CompileUnit::allocateTypeDie(TypeEntryBody *TypeDescriptor,
                                  DIEGenerator &TypeDIEGenerator,
                                  dwarf::Tag DieTag, bool IsDeclaration,
                                  bool IsParentDeclaration) {
  uint64_t Priority = getPriority();
 
  // Lock-free pre-checks: skip the lock (and downstream cloning) when this CU
  // has no chance of winning the type slot.
  if (!IsDeclaration && !IsParentDeclaration) {
    // DiePriority only ever decreases, so a relaxed read that is <= our
    // priority means we definitely cannot win.
    if (Priority >= TypeDescriptor->DiePriority.load(std::memory_order_relaxed))
      return nullptr;
  } else {
    // Once a definition exists the declaration slot is dead.
    if (TypeDescriptor->Die.load(std::memory_order_relaxed))
      return nullptr;
  }
 
  while (TypeDescriptor->Lock.test_and_set(std::memory_order_acquire))
    ; // spin
 
  DIE *Result = nullptr;
 
  if (!IsDeclaration && !IsParentDeclaration) {
    // Definition: lowest priority wins.
    if (Priority <
        TypeDescriptor->DiePriority.load(std::memory_order_relaxed)) {
      TypeDescriptor->DiePriority.store(Priority, std::memory_order_relaxed);
      Result = TypeDIEGenerator.createDIE(DieTag, 0);
      TypeDescriptor->Die.store(Result, std::memory_order_relaxed);
    }
  } else if (!TypeDescriptor->Die.load(std::memory_order_relaxed)) {
    // Declaration (no definition exists yet).
    // Prefer declarations whose parent is a definition (better context);
    // break ties by CU priority (lower wins).
    bool WorseParent =
        IsParentDeclaration && !TypeDescriptor->DeclarationParentIsDeclaration;
    bool BetterParent =
        !IsParentDeclaration && TypeDescriptor->DeclarationParentIsDeclaration;
    if (!WorseParent &&
        (BetterParent || Priority < TypeDescriptor->DeclarationDiePriority)) {
      TypeDescriptor->DeclarationDiePriority = Priority;
      TypeDescriptor->DeclarationParentIsDeclaration = IsParentDeclaration;
      Result = TypeDIEGenerator.createDIE(DieTag, 0);
      TypeDescriptor->DeclarationDie.store(Result, std::memory_order_relaxed);
    }
  }
 
  TypeDescriptor->Lock.clear(std::memory_order_release);
  return Result;
}
 
TypeEntry *CompileUnit::createTypeDIEandCloneAttributes(
    const DWARFDebugInfoEntry *InputDieEntry, DIEGenerator &TypeDIEGenerator,
    TypeEntry *ClonedParentTypeDIE, TypeUnit *ArtificialTypeUnit,
    uint32_t SiblingOrdinal) {
  assert(ArtificialTypeUnit != nullptr);
  uint32_t InputDieIdx = getDIEIndex(InputDieEntry);
 
  TypeEntry *Entry = getDieTypeEntry(InputDieIdx);
  assert(Entry != nullptr);
  assert(ClonedParentTypeDIE != nullptr);
  TypeEntryBody *EntryBody =
      ArtificialTypeUnit->getTypePool().getOrCreateTypeEntryBody(
          Entry, ClonedParentTypeDIE);
  assert(EntryBody);
 
  // Min-merge this child's ordinal in its parent's child list so children of
  // record-like types (class/struct/union/interface) sort in source order.
  // Min across CUs because Clang appends template instantiations lazily, so
  // positions vary between CUs.
  if (std::optional<uint32_t> ParentIdx = InputDieEntry->getParentIdx()) {
    dwarf::Tag ParentTag = getDebugInfoEntry(*ParentIdx)->getTag();
    if (ParentTag == dwarf::DW_TAG_structure_type ||
        ParentTag == dwarf::DW_TAG_class_type ||
        ParentTag == dwarf::DW_TAG_union_type ||
        ParentTag == dwarf::DW_TAG_interface_type) {
      uint32_t Prev = EntryBody->SortKey.load(std::memory_order_relaxed);
      while (SiblingOrdinal < Prev &&
             !EntryBody->SortKey.compare_exchange_weak(
                 Prev, SiblingOrdinal, std::memory_order_relaxed,
                 std::memory_order_relaxed))
        ;
    }
  }
 
  bool IsDeclaration =
      dwarf::toUnsigned(find(InputDieEntry, dwarf::DW_AT_declaration), 0);
 
  bool ParentIsDeclaration = false;
  if (std::optional<uint32_t> ParentIdx = InputDieEntry->getParentIdx())
    ParentIsDeclaration =
        dwarf::toUnsigned(find(*ParentIdx, dwarf::DW_AT_declaration), 0);
 
  DIE *OutDIE =
      allocateTypeDie(EntryBody, TypeDIEGenerator, InputDieEntry->getTag(),
                      IsDeclaration, ParentIsDeclaration);
 
  if (OutDIE != nullptr) {
    assert(ArtificialTypeUnit != nullptr);
    ArtificialTypeUnit->getSectionDescriptor(DebugSectionKind::DebugInfo);
 
    DIEAttributeCloner AttributesCloner(OutDIE, *this, ArtificialTypeUnit,
                                        InputDieEntry, TypeDIEGenerator,
                                        std::nullopt, std::nullopt, false);
    AttributesCloner.clone();
 
    // Remember accelerator info.
    AcceleratorRecordsSaver AccelRecordsSaver(getGlobalData(), *this,
                                              ArtificialTypeUnit);
    AccelRecordsSaver.save(InputDieEntry, OutDIE, AttributesCloner.AttrInfo,
                           Entry);
 
    // if AttributesCloner.getOutOffset() == 0 then we need to add
    // 1 to avoid assertion for zero size. We will subtract it back later.
    OutDIE->setSize(AttributesCloner.getOutOffset() + 1);
  }
 
  return Entry;
}
 
Error CompileUnit::cloneAndEmitLineTable(const Triple &TargetTriple) {
  const DWARFDebugLine::LineTable *InputLineTable =
      getContainingFile().Dwarf->getLineTableForUnit(&getOrigUnit());
  if (InputLineTable == nullptr) {
    if (getOrigUnit().getUnitDIE().find(dwarf::DW_AT_stmt_list))
      warn("cann't load line table.");
    return Error::success();
  }
 
  DWARFDebugLine::LineTable OutLineTable;
 
  // Set Line Table header.
  OutLineTable.Prologue = InputLineTable->Prologue;
  OutLineTable.Prologue.FormParams.AddrSize = getFormParams().AddrSize;
 
  // Set Line Table Rows.
  if (getGlobalData().getOptions().UpdateIndexTablesOnly) {
    OutLineTable.Rows = InputLineTable->Rows;
    // If all the line table contains is a DW_LNE_end_sequence, clear the line
    // table rows, it will be inserted again in the DWARFStreamer.
    if (OutLineTable.Rows.size() == 1 && OutLineTable.Rows[0].EndSequence)
      OutLineTable.Rows.clear();
 
    OutLineTable.Sequences = InputLineTable->Sequences;
    return emitDebugLine(TargetTriple, OutLineTable);
  }
 
  SmallVector<uint64_t> OrigRowIndices;
  filterLineTableRows(*InputLineTable, OutLineTable.Rows, OrigRowIndices);
 
  if (StmtSeqListAttributes.empty())
    return emitDebugLine(TargetTriple, OutLineTable);
 
  // When DW_AT_LLVM_stmt_sequence attributes on this CU need their values
  // rewritten to point at the correct output sequence, have the emitter
  // record, for every row that originated from an input row, the byte
  // offset of the DW_LNE_set_address that opens the sequence containing
  // that row. Keying the map on the input row index (rather than on an
  // output address) avoids collisions when two input sequences would
  // relocate to the same output address — e.g. ICF folding two functions
  // from the same CU to a single output range.
  //
  // The patching below MUST run before emitDebugInfo() serializes the
  // DIE bytes and before OutputSections::applyPatches() runs for this
  // unit's .debug_info — it writes a local offset into the DIEValue that
  // the serializer then emits, and a DebugOffsetPatch (registered at DIE
  // cloning time) later adds the CU's .debug_line start offset to reach
  // the final absolute value.
  DenseMap<uint64_t, uint64_t> RowIndexToSeqStartOffset;
  if (Error Err = emitDebugLine(TargetTriple, OutLineTable, OrigRowIndices,
                                &RowIndexToSeqStartOffset))
    return Err;
 
  DenseMap<uint64_t, uint64_t> SeqOffsetToFirstRowIndex =
      buildStmtSeqOffsetToFirstRowIndex(*InputLineTable);
  patchStmtSeqAttributes(SeqOffsetToFirstRowIndex, RowIndexToSeqStartOffset);
  return Error::success();
}
 
void CompileUnit::filterLineTableRows(
    const DWARFDebugLine::LineTable &InputLineTable,
    std::vector<DWARFDebugLine::Row> &NewRows,
    SmallVectorImpl<uint64_t> &NewRowIndices) {
  NewRows.reserve(InputLineTable.Rows.size());
  NewRowIndices.reserve(InputLineTable.Rows.size());
 
  // Current sequence of rows being extracted, before being inserted
  // in NewRows. Kept in lockstep with SeqIndices, which stores the
  // originating input row index (or InvalidRowIndex for manufactured
  // end-of-range rows).
  std::vector<DWARFDebugLine::Row> Seq;
  SmallVector<uint64_t> SeqIndices;
  constexpr uint64_t InvalidRowIndex = std::numeric_limits<uint64_t>::max();
 
  const auto &FunctionRanges = getFunctionRanges();
  std::optional<AddressRangeValuePair> CurrRange;
 
  // FIXME: This logic is meant to generate exactly the same output as
  // Darwin's classic dsymutil. There is a nicer way to implement this
  // by simply putting all the relocated line info in NewRows and simply
  // sorting NewRows before passing it to emitLineTableForUnit. This
  // should be correct as sequences for a function should stay
  // together in the sorted output. There are a few corner cases that
  // look suspicious though, and that required to implement the logic
  // this way. Revisit that once initial validation is finished.
 
  // Iterate over the object file line info and extract the sequences
  // that correspond to linked functions.
  for (auto [InputRowIdx, InputRow] : llvm::enumerate(InputLineTable.Rows)) {
    DWARFDebugLine::Row Row = InputRow;
    // Check whether we stepped out of the range. The range is
    // half-open, but consider accept the end address of the range if
    // it is marked as end_sequence in the input (because in that
    // case, the relocation offset is accurate and that entry won't
    // serve as the start of another function).
    if (!CurrRange || !CurrRange->Range.contains(Row.Address.Address)) {
      // We just stepped out of a known range. Insert a end_sequence
      // corresponding to the end of the range.
      uint64_t StopAddress =
          CurrRange ? CurrRange->Range.end() + CurrRange->Value : -1ULL;
      CurrRange = FunctionRanges.getRangeThatContains(Row.Address.Address);
      if (StopAddress != -1ULL && !Seq.empty()) {
        // Insert end sequence row with the computed end address, but
        // the same line as the previous one. This row is synthesised
        // and has no input counterpart, so tag it with
        // InvalidRowIndex.
        auto NextLine = Seq.back();
        NextLine.Address.Address = StopAddress;
        NextLine.EndSequence = 1;
        NextLine.PrologueEnd = 0;
        NextLine.BasicBlock = 0;
        NextLine.EpilogueBegin = 0;
        Seq.push_back(NextLine);
        SeqIndices.push_back(InvalidRowIndex);
        insertLineSequence(Seq, SeqIndices, NewRows, NewRowIndices);
      }
 
      if (!CurrRange)
        continue;
    }
 
    // Ignore empty sequences.
    if (Row.EndSequence && Seq.empty())
      continue;
 
    // Relocate row address and add it to the current sequence.
    Row.Address.Address += CurrRange->Value;
    Seq.emplace_back(Row);
    SeqIndices.push_back(InputRowIdx);
 
    if (Row.EndSequence)
      insertLineSequence(Seq, SeqIndices, NewRows, NewRowIndices);
  }
}
 
void CompileUnit::patchStmtSeqAttributes(
    const DenseMap<uint64_t, uint64_t> &SeqOffsetToFirstRowIndex,
    const DenseMap<uint64_t, uint64_t> &RowIndexToSeqStartOffset) {
  const uint64_t InvalidOffset = getFormParams().getDwarfMaxOffset();
 
  for (const CompileUnit::StmtSeqPatch &Patch : StmtSeqListAttributes) {
    uint64_t NewStmtSeq = InvalidOffset;
    auto RowIt = SeqOffsetToFirstRowIndex.find(Patch.InputStmtSeqOffset);
    if (RowIt != SeqOffsetToFirstRowIndex.end()) {
      auto OffIt = RowIndexToSeqStartOffset.find(RowIt->second);
      if (OffIt != RowIndexToSeqStartOffset.end())
        NewStmtSeq = OffIt->second;
    }
    // When resolution fails, the InvalidOffset sentinel must survive the
    // combination-time section-offset fixup. The patch applier preserves
    // InvalidOffset as-is so consumers see a clean invalid marker rather
    // than StartOffset - 1.
    *Patch.Value = DIEValue(Patch.Value->getAttribute(), Patch.Value->getForm(),
                            DIEInteger(NewStmtSeq));
  }
}
 
DenseMap<uint64_t, uint64_t> CompileUnit::buildStmtSeqOffsetToFirstRowIndex(
    const DWARFDebugLine::LineTable &InputLineTable) const {
  // Collect this CU's stmt-sequence attribute values (input offsets),
  // sorted ascending and deduplicated.
  SmallVector<uint64_t> StmtAttrs;
  StmtAttrs.reserve(StmtSeqListAttributes.size());
  for (const StmtSeqPatch &Patch : StmtSeqListAttributes)
    StmtAttrs.push_back(Patch.InputStmtSeqOffset);
  llvm::sort(StmtAttrs);
  StmtAttrs.erase(llvm::unique(StmtAttrs), StmtAttrs.end());
 
  DenseMap<uint64_t, uint64_t> Result;
  dwarf_linker::buildStmtSeqOffsetToFirstRowIndex(InputLineTable, StmtAttrs,
                                                  Result);
  return Result;
}
 
void CompileUnit::insertLineSequence(std::vector<DWARFDebugLine::Row> &Seq,
                                     SmallVectorImpl<uint64_t> &SeqIndices,
                                     std::vector<DWARFDebugLine::Row> &Rows,
                                     SmallVectorImpl<uint64_t> &RowIndices) {
  assert(Seq.size() == SeqIndices.size() &&
         "Seq and SeqIndices must be kept in lockstep");
  assert(Rows.size() == RowIndices.size() &&
         "Rows and RowIndices must be kept in lockstep");
  if (Seq.empty())
    return;
 
  auto ClearSeq = [&] {
    Seq.clear();
    SeqIndices.clear();
  };
 
  if (!Rows.empty() && Rows.back().Address < Seq.front().Address) {
    llvm::append_range(Rows, Seq);
    llvm::append_range(RowIndices, SeqIndices);
    ClearSeq();
    return;
  }
 
  object::SectionedAddress Front = Seq.front().Address;
  auto InsertPoint = partition_point(
      Rows, [=](const DWARFDebugLine::Row &O) { return O.Address < Front; });
  size_t InsertIdx = std::distance(Rows.begin(), InsertPoint);
 
  // FIXME: this only removes the unneeded end_sequence if the
  // sequences have been inserted in order. Using a global sort like
  // described in cloneAndEmitLineTable() and delaying the end_sequene
  // elimination to DebugLineEmitter::emit() we can get rid of all of them.
  if (InsertPoint != Rows.end() && InsertPoint->Address == Front &&
      InsertPoint->EndSequence) {
    *InsertPoint = Seq.front();
    RowIndices[InsertIdx] = SeqIndices.front();
    Rows.insert(InsertPoint + 1, Seq.begin() + 1, Seq.end());
    RowIndices.insert(RowIndices.begin() + InsertIdx + 1,
                      SeqIndices.begin() + 1, SeqIndices.end());
  } else {
    Rows.insert(InsertPoint, Seq.begin(), Seq.end());
    RowIndices.insert(RowIndices.begin() + InsertIdx, SeqIndices.begin(),
                      SeqIndices.end());
  }
 
  ClearSeq();
}
 
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void CompileUnit::DIEInfo::dump() {
  llvm::errs() << "{";
  llvm::errs() << "  Placement: ";
  switch (getPlacement()) {
  case NotSet:
    llvm::errs() << "NotSet";
    break;
  case TypeTable:
    llvm::errs() << "TypeTable";
    break;
  case PlainDwarf:
    llvm::errs() << "PlainDwarf";
    break;
  case Both:
    llvm::errs() << "Both";
    break;
  }
 
  llvm::errs() << "  Keep: " << getKeep();
  llvm::errs() << "  KeepPlainChildren: " << getKeepPlainChildren();
  llvm::errs() << "  KeepTypeChildren: " << getKeepTypeChildren();
  llvm::errs() << "  IsInMouduleScope: " << getIsInMouduleScope();
  llvm::errs() << "  IsInFunctionScope: " << getIsInFunctionScope();
  llvm::errs() << "  IsInAnonNamespaceScope: " << getIsInAnonNamespaceScope();
  llvm::errs() << "  ODRAvailable: " << getODRAvailable();
  llvm::errs() << "  TrackLiveness: " << getTrackLiveness();
  llvm::errs() << "}\n";
}
#endif // if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 
std::optional<std::pair<StringRef, StringRef>>
CompileUnit::getDirAndFilenameFromLineTable(
    const DWARFFormValue &FileIdxValue) {
  uint64_t FileIdx;
  if (std::optional<uint64_t> Val = FileIdxValue.getAsUnsignedConstant())
    FileIdx = *Val;
  else if (std::optional<int64_t> Val = FileIdxValue.getAsSignedConstant())
    FileIdx = *Val;
  else if (std::optional<uint64_t> Val = FileIdxValue.getAsSectionOffset())
    FileIdx = *Val;
  else
    return std::nullopt;
 
  return getDirAndFilenameFromLineTable(FileIdx);
}
 
std::optional<std::pair<StringRef, StringRef>>
CompileUnit::getDirAndFilenameFromLineTable(uint64_t FileIdx) {
  std::lock_guard<std::mutex> Guard(FileNamesMutex);
  FileNamesCache::iterator FileData = FileNames.find(FileIdx);
  if (FileData != FileNames.end())
    return {{StringRef(FileData->second->first),
             StringRef(FileData->second->second)}};
 
  if (const DWARFDebugLine::LineTable *LineTable =
          getOrigUnit().getContext().getLineTableForUnit(&getOrigUnit())) {
    if (LineTable->hasFileAtIndex(FileIdx)) {
 
      const llvm::DWARFDebugLine::FileNameEntry &Entry =
          LineTable->Prologue.getFileNameEntry(FileIdx);
 
      Expected<const char *> Name = Entry.Name.getAsCString();
      if (!Name) {
        warn(Name.takeError());
        return std::nullopt;
      }
 
      std::string FileName = *Name;
      if (isPathAbsoluteOnWindowsOrPosix(FileName)) {
        FileNamesCache::iterator FileData =
            FileNames
                .insert({FileIdx,
                         std::make_unique<std::pair<std::string, std::string>>(
                             std::string(""), std::move(FileName))})
                .first;
        return {{StringRef(FileData->second->first),
                 StringRef(FileData->second->second)}};
      }
 
      SmallString<256> FilePath;
      StringRef IncludeDir;
      // Be defensive about the contents of Entry.
      if (getVersion() >= 5) {
        // DirIdx 0 is the compilation directory, so don't include it for
        // relative names.
        if ((Entry.DirIdx != 0) &&
            Entry.DirIdx < LineTable->Prologue.IncludeDirectories.size()) {
          Expected<const char *> DirName =
              LineTable->Prologue.IncludeDirectories[Entry.DirIdx]
                  .getAsCString();
          if (DirName)
            IncludeDir = *DirName;
          else {
            warn(DirName.takeError());
            return std::nullopt;
          }
        }
      } else {
        if (0 < Entry.DirIdx &&
            Entry.DirIdx <= LineTable->Prologue.IncludeDirectories.size()) {
          Expected<const char *> DirName =
              LineTable->Prologue.IncludeDirectories[Entry.DirIdx - 1]
                  .getAsCString();
          if (DirName)
            IncludeDir = *DirName;
          else {
            warn(DirName.takeError());
            return std::nullopt;
          }
        }
      }
 
      StringRef CompDir = getOrigUnit().getCompilationDir();
 
      if (!CompDir.empty() && !isPathAbsoluteOnWindowsOrPosix(IncludeDir)) {
        sys::path::append(FilePath, sys::path::Style::native, CompDir);
      }
 
      sys::path::append(FilePath, sys::path::Style::native, IncludeDir);
 
      FileNamesCache::iterator FileData =
          FileNames
              .insert({FileIdx,
                       std::make_unique<std::pair<std::string, std::string>>(
                           std::string(FilePath), std::move(FileName))})
              .first;
      return {{StringRef(FileData->second->first),
               StringRef(FileData->second->second)}};
    }
  }
 
  return std::nullopt;
}
 
#define MAX_REFERENCIES_DEPTH 1000
UnitEntryPairTy UnitEntryPairTy::getNamespaceOrigin() {
  UnitEntryPairTy CUDiePair(*this);
  std::optional<UnitEntryPairTy> RefDiePair;
  int refDepth = 0;
  do {
    RefDiePair = CUDiePair.CU->resolveDIEReference(
        CUDiePair.DieEntry, dwarf::DW_AT_extension,
        ResolveInterCUReferencesMode::Resolve);
    if (!RefDiePair || !RefDiePair->DieEntry)
      return CUDiePair;
 
    CUDiePair = *RefDiePair;
  } while (refDepth++ < MAX_REFERENCIES_DEPTH);
 
  return CUDiePair;
}
 
std::optional<UnitEntryPairTy> UnitEntryPairTy::getParent() {
  if (std::optional<uint32_t> ParentIdx = DieEntry->getParentIdx())
    return UnitEntryPairTy{CU, CU->getDebugInfoEntry(*ParentIdx)};
 
  return std::nullopt;
}
 
CompileUnit::OutputUnitVariantPtr::OutputUnitVariantPtr(CompileUnit *U)
    : Ptr(U) {
  assert(U != nullptr);
}
 
CompileUnit::OutputUnitVariantPtr::OutputUnitVariantPtr(TypeUnit *U) : Ptr(U) {
  assert(U != nullptr);
}
 
DwarfUnit *CompileUnit::OutputUnitVariantPtr::operator->() {
  if (isCompileUnit())
    return getAsCompileUnit();
  else
    return getAsTypeUnit();
}
 
bool CompileUnit::OutputUnitVariantPtr::isCompileUnit() {
  return isa<CompileUnit *>(Ptr);
}
 
bool CompileUnit::OutputUnitVariantPtr::isTypeUnit() {
  return isa<TypeUnit *>(Ptr);
}
 
CompileUnit *CompileUnit::OutputUnitVariantPtr::getAsCompileUnit() {
  return cast<CompileUnit *>(Ptr);
}
 
TypeUnit *CompileUnit::OutputUnitVariantPtr::getAsTypeUnit() {
  return cast<TypeUnit *>(Ptr);
}
 
bool CompileUnit::resolveDependenciesAndMarkLiveness(
    bool InterCUProcessingStarted, std::atomic<bool> &HasNewInterconnectedCUs) {
  if (!Dependencies)
    Dependencies.reset(new DependencyTracker(*this));
 
  return Dependencies->resolveDependenciesAndMarkLiveness(
      InterCUProcessingStarted, HasNewInterconnectedCUs);
}
 
bool CompileUnit::updateDependenciesCompleteness() {
  assert(Dependencies.get());
 
  return Dependencies->updateDependenciesCompleteness();
}
 
void CompileUnit::verifyDependencies() {
  assert(Dependencies.get());
 
  Dependencies->verifyKeepChain();
}
 
ArrayRef<dwarf::Attribute> dwarf_linker::parallel::getODRAttributes() {
  static dwarf::Attribute ODRAttributes[] = {
      dwarf::DW_AT_type, dwarf::DW_AT_specification,
      dwarf::DW_AT_abstract_origin, dwarf::DW_AT_import,
      dwarf::DW_AT_LLVM_alloc_type};
 
  return ODRAttributes;
}