vendor/llvm-project/llvmorg-18-init-14265-ga17671084db1

3 files changed, 222 insertions, 202 deletions

diff --git a/llvm/lib/DWARFLinker/DWARFLinker.cpp b/llvm/lib/DWARFLinker/DWARFLinker.cpp
index e6eccb20114a..1a7ea47adc5c 100644
--- a/llvm/lib/DWARFLinker/DWARFLinker.cpp
+++ b/llvm/lib/DWARFLinker/DWARFLinker.cpp
@@ -15,6 +15,7 @@
 #include "llvm/DWARFLinker/DWARFLinkerDeclContext.h"
 #include "llvm/DWARFLinker/DWARFStreamer.h"
 #include "llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h"
+#include "llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h"
 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
 #include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugLine.h"
@@ -140,37 +141,6 @@ AddressesMap::~AddressesMap() = default;
 
 DwarfEmitter::~DwarfEmitter() = default;
 
-static std::optional<StringRef> StripTemplateParameters(StringRef Name) {
-  // We are looking for template parameters to strip from Name. e.g.
-  //
-  //  operator<<B>
-  //
-  // We look for > at the end but if it does not contain any < then we
-  // have something like operator>>. We check for the operator<=> case.
-  if (!Name.endswith(">") || Name.count("<") == 0 || Name.endswith("<=>"))
-    return {};
-
-  // How many < until we have the start of the template parameters.
-  size_t NumLeftAnglesToSkip = 1;
-
-  // If we have operator<=> then we need to skip its < as well.
-  NumLeftAnglesToSkip += Name.count("<=>");
-
-  size_t RightAngleCount = Name.count('>');
-  size_t LeftAngleCount = Name.count('<');
-
-  // If we have more < than > we have operator< or operator<<
-  // we to account for their < as well.
-  if (LeftAngleCount > RightAngleCount)
-    NumLeftAnglesToSkip += LeftAngleCount - RightAngleCount;
-
-  size_t StartOfTemplate = 0;
-  while (NumLeftAnglesToSkip--)
-    StartOfTemplate = Name.find('<', StartOfTemplate) + 1;
-
-  return Name.substr(0, StartOfTemplate - 1);
-}
-
 bool DWARFLinker::DIECloner::getDIENames(const DWARFDie &Die,
                                          AttributesInfo &Info,
                                          OffsetsStringPool &StringPool,
@@ -207,6 +177,20 @@ static void resolveRelativeObjectPath(SmallVectorImpl<char> &Buf, DWARFDie CU) {
   sys::path::append(Buf, dwarf::toString(CU.find(dwarf::DW_AT_comp_dir), ""));
 }
 
+/// Make a best effort to guess the
+/// Xcode.app/Contents/Developer/Toolchains/ path from an SDK path.
+static SmallString<128> guessToolchainBaseDir(StringRef SysRoot) {
+  SmallString<128> Result;
+  // Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk
+  StringRef Base = sys::path::parent_path(SysRoot);
+  if (sys::path::filename(Base) != "SDKs")
+    return Result;
+  Base = sys::path::parent_path(Base);
+  Result = Base;
+  Result += "/Toolchains";
+  return Result;
+}
+
 /// Collect references to parseable Swift interfaces in imported
 /// DW_TAG_module blocks.
 static void analyzeImportedModule(
@@ -228,6 +212,11 @@ static void analyzeImportedModule(
     SysRoot = CU.getSysRoot();
   if (!SysRoot.empty() && Path.startswith(SysRoot))
     return;
+  // Don't track interfaces that are part of the toolchain.
+  // For example: Swift, _Concurrency, ...
+  SmallString<128> Toolchain = guessToolchainBaseDir(SysRoot);
+  if (!Toolchain.empty() && Path.startswith(Toolchain))
+    return;
   std::optional<const char *> Name =
       dwarf::toString(DIE.find(dwarf::DW_AT_name));
   if (!Name)
@@ -474,8 +463,10 @@ DWARFLinker::getVariableRelocAdjustment(AddressesMap &RelocMgr,
 
     const DWARFExpression::Operation &Op = *It;
     switch (Op.getCode()) {
+    case dwarf::DW_OP_const2u:
     case dwarf::DW_OP_const4u:
     case dwarf::DW_OP_const8u:
+    case dwarf::DW_OP_const2s:
     case dwarf::DW_OP_const4s:
     case dwarf::DW_OP_const8s:
       if (NextIt == Expression.end() || !isTlsAddressCode(NextIt->getCode()))
@@ -1044,32 +1035,45 @@ void DWARFLinker::assignAbbrev(DIEAbbrev &Abbrev) {
 unsigned DWARFLinker::DIECloner::cloneStringAttribute(DIE &Die,
                                                       AttributeSpec AttrSpec,
                                                       const DWARFFormValue &Val,
-                                                      const DWARFUnit &,
+                                                      const DWARFUnit &U,
                                                       AttributesInfo &Info) {
   std::optional<const char *> String = dwarf::toString(Val);
   if (!String)
     return 0;
-
   DwarfStringPoolEntryRef StringEntry;
   if (AttrSpec.Form == dwarf::DW_FORM_line_strp) {
     StringEntry = DebugLineStrPool.getEntry(*String);
   } else {
     StringEntry = DebugStrPool.getEntry(*String);
 
+    if (AttrSpec.Attr == dwarf::DW_AT_APPLE_origin) {
+      Info.HasAppleOrigin = true;
+      if (std::optional<StringRef> FileName =
+              ObjFile.Addresses->getLibraryInstallName()) {
+        StringEntry = DebugStrPool.getEntry(*FileName);
+      }
+    }
+
     // Update attributes info.
     if (AttrSpec.Attr == dwarf::DW_AT_name)
       Info.Name = StringEntry;
     else if (AttrSpec.Attr == dwarf::DW_AT_MIPS_linkage_name ||
              AttrSpec.Attr == dwarf::DW_AT_linkage_name)
       Info.MangledName = StringEntry;
-
+    if (U.getVersion() >= 5) {
+      // Switch everything to DW_FORM_strx strings.
+      auto StringOffsetIndex =
+          StringOffsetPool.getValueIndex(StringEntry.getOffset());
+      return Die
+          .addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
+                    dwarf::DW_FORM_strx, DIEInteger(StringOffsetIndex))
+          ->sizeOf(U.getFormParams());
+    }
     // Switch everything to out of line strings.
     AttrSpec.Form = dwarf::DW_FORM_strp;
   }
-
   Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr), AttrSpec.Form,
                DIEInteger(StringEntry.getOffset()));
-
   return 4;
 }
 
@@ -1389,7 +1393,7 @@ unsigned DWARFLinker::DIECloner::cloneAddressAttribute(
     return Unit.getOrigUnit().getAddressByteSize();
   }
 
-  auto AddrIndex = AddrPool.getAddrIndex(*Addr);
+  auto AddrIndex = AddrPool.getValueIndex(*Addr);
 
   return Die
       .addValue(DIEAlloc, static_cast<dwarf::Attribute>(AttrSpec.Attr),
@@ -1421,6 +1425,17 @@ unsigned DWARFLinker::DIECloner::cloneScalarAttribute(
     }
   }
 
+  if (AttrSpec.Attr == dwarf::DW_AT_str_offsets_base) {
+    // DWARFLinker generates common .debug_str_offsets table used for all
+    // compile units. The offset to the common .debug_str_offsets table is 8 on
+    // DWARF32.
+    Info.AttrStrOffsetBaseSeen = true;
+    return Die
+        .addValue(DIEAlloc, dwarf::DW_AT_str_offsets_base,
+                  dwarf::DW_FORM_sec_offset, DIEInteger(8))
+        ->sizeOf(Unit.getOrigUnit().getFormParams());
+  }
+
   if (LLVM_UNLIKELY(Linker.Options.Update)) {
     if (auto OptionalValue = Val.getAsUnsignedConstant())
       Value = *OptionalValue;
@@ -1600,51 +1615,25 @@ unsigned DWARFLinker::DIECloner::cloneAttribute(
   return 0;
 }
 
-static bool isObjCSelector(StringRef Name) {
-  return Name.size() > 2 && (Name[0] == '-' || Name[0] == '+') &&
-         (Name[1] == '[');
-}
-
 void DWARFLinker::DIECloner::addObjCAccelerator(CompileUnit &Unit,
                                                 const DIE *Die,
                                                 DwarfStringPoolEntryRef Name,
                                                 OffsetsStringPool &StringPool,
                                                 bool SkipPubSection) {
-  assert(isObjCSelector(Name.getString()) && "not an objc selector");
-  // Objective C method or class function.
-  // "- [Class(Category) selector :withArg ...]"
-  StringRef ClassNameStart(Name.getString().drop_front(2));
-  size_t FirstSpace = ClassNameStart.find(' ');
-  if (FirstSpace == StringRef::npos)
+  std::optional<ObjCSelectorNames> Names =
+      getObjCNamesIfSelector(Name.getString());
+  if (!Names)
     return;
-
-  StringRef SelectorStart(ClassNameStart.data() + FirstSpace + 1);
-  if (!SelectorStart.size())
-    return;
-
-  StringRef Selector(SelectorStart.data(), SelectorStart.size() - 1);
-  Unit.addNameAccelerator(Die, StringPool.getEntry(Selector), SkipPubSection);
-
-  // Add an entry for the class name that points to this
-  // method/class function.
-  StringRef ClassName(ClassNameStart.data(), FirstSpace);
-  Unit.addObjCAccelerator(Die, StringPool.getEntry(ClassName), SkipPubSection);
-
-  if (ClassName[ClassName.size() - 1] == ')') {
-    size_t OpenParens = ClassName.find('(');
-    if (OpenParens != StringRef::npos) {
-      StringRef ClassNameNoCategory(ClassName.data(), OpenParens);
-      Unit.addObjCAccelerator(Die, StringPool.getEntry(ClassNameNoCategory),
-                              SkipPubSection);
-
-      std::string MethodNameNoCategory(Name.getString().data(), OpenParens + 2);
-      // FIXME: The missing space here may be a bug, but
-      //        dsymutil-classic also does it this way.
-      MethodNameNoCategory.append(std::string(SelectorStart));
-      Unit.addNameAccelerator(Die, StringPool.getEntry(MethodNameNoCategory),
-                              SkipPubSection);
-    }
-  }
+  Unit.addNameAccelerator(Die, StringPool.getEntry(Names->Selector),
+                          SkipPubSection);
+  Unit.addObjCAccelerator(Die, StringPool.getEntry(Names->ClassName),
+                          SkipPubSection);
+  if (Names->ClassNameNoCategory)
+    Unit.addObjCAccelerator(
+        Die, StringPool.getEntry(*Names->ClassNameNoCategory), SkipPubSection);
+  if (Names->MethodNameNoCategory)
+    Unit.addNameAccelerator(
+        Die, StringPool.getEntry(*Names->MethodNameNoCategory), SkipPubSection);
 }
 
 static bool
@@ -1664,9 +1653,6 @@ shouldSkipAttribute(bool Update,
     // Since DW_AT_rnglists_base is used for only DW_FORM_rnglistx the
     // DW_AT_rnglists_base is removed.
     return !Update;
-  case dwarf::DW_AT_str_offsets_base:
-    // FIXME: Use the string offset table with Dwarf 5.
-    return true;
   case dwarf::DW_AT_loclists_base:
     // In case !Update the .debug_addr table is not generated/preserved.
     // Thus instead of DW_FORM_loclistx the DW_FORM_sec_offset is used.
@@ -1679,6 +1665,12 @@ shouldSkipAttribute(bool Update,
   }
 }
 
+struct AttributeLinkedOffsetFixup {
+  int64_t LinkedOffsetFixupVal;
+  uint64_t InputAttrStartOffset;
+  uint64_t InputAttrEndOffset;
+};
+
 DIE *DWARFLinker::DIECloner::cloneDIE(const DWARFDie &InputDIE,
                                       const DWARFFile &File, CompileUnit &Unit,
                                       int64_t PCOffset, uint32_t OutOffset,
@@ -1762,6 +1754,9 @@ DIE *DWARFLinker::DIECloner::cloneDIE(const DWARFDie &InputDIE,
       Flags |= TF_SkipPC;
   }
 
+  std::optional<StringRef> LibraryInstallName =
+      ObjFile.Addresses->getLibraryInstallName();
+  SmallVector<AttributeLinkedOffsetFixup> AttributesFixups;
   for (const auto &AttrSpec : Abbrev->attributes()) {
     if (shouldSkipAttribute(Update, AttrSpec, Flags & TF_SkipPC)) {
       DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset,
@@ -1769,17 +1764,41 @@ DIE *DWARFLinker::DIECloner::cloneDIE(const DWARFDie &InputDIE,
       continue;
     }
 
+    AttributeLinkedOffsetFixup CurAttrFixup;
+    CurAttrFixup.InputAttrStartOffset = InputDIE.getOffset() + Offset;
+    CurAttrFixup.LinkedOffsetFixupVal =
+        Unit.getStartOffset() + OutOffset - CurAttrFixup.InputAttrStartOffset;
+
     DWARFFormValue Val = AttrSpec.getFormValue();
     uint64_t AttrSize = Offset;
     Val.extractValue(Data, &Offset, U.getFormParams(), &U);
+    CurAttrFixup.InputAttrEndOffset = InputDIE.getOffset() + Offset;
     AttrSize = Offset - AttrSize;
 
-    OutOffset += cloneAttribute(*Die, InputDIE, File, Unit, Val, AttrSpec,
-                                AttrSize, AttrInfo, IsLittleEndian);
+    uint64_t FinalAttrSize =
+        cloneAttribute(*Die, InputDIE, File, Unit, Val, AttrSpec, AttrSize,
+                       AttrInfo, IsLittleEndian);
+    if (FinalAttrSize != 0 && ObjFile.Addresses->needToSaveValidRelocs())
+      AttributesFixups.push_back(CurAttrFixup);
+
+    OutOffset += FinalAttrSize;
   }
 
-  // Look for accelerator entries.
   uint16_t Tag = InputDIE.getTag();
+  // Add the DW_AT_APPLE_origin attribute to Compile Unit die if we have
+  // an install name and the DWARF doesn't have the attribute yet.
+  const bool NeedsAppleOrigin = (Tag == dwarf::DW_TAG_compile_unit) &&
+                                LibraryInstallName.has_value() &&
+                                !AttrInfo.HasAppleOrigin;
+  if (NeedsAppleOrigin) {
+    auto StringEntry = DebugStrPool.getEntry(LibraryInstallName.value());
+    Die->addValue(DIEAlloc, dwarf::Attribute(dwarf::DW_AT_APPLE_origin),
+                  dwarf::DW_FORM_strp, DIEInteger(StringEntry.getOffset()));
+    AttrInfo.Name = StringEntry;
+    OutOffset += 4;
+  }
+
+  // Look for accelerator entries.
   // FIXME: This is slightly wrong. An inline_subroutine without a
   // low_pc, but with AT_ranges might be interesting to get into the
   // accelerator tables too. For now stick with dsymutil's behavior.
@@ -1797,7 +1816,7 @@ DIE *DWARFLinker::DIECloner::cloneDIE(const DWARFDie &InputDIE,
       Unit.addNameAccelerator(Die, AttrInfo.Name,
                               Tag == dwarf::DW_TAG_inlined_subroutine);
     }
-    if (AttrInfo.Name && isObjCSelector(AttrInfo.Name.getString()))
+    if (AttrInfo.Name)
       addObjCAccelerator(Unit, Die, AttrInfo.Name, DebugStrPool,
                          /* SkipPubSection =*/true);
 
@@ -1833,6 +1852,14 @@ DIE *DWARFLinker::DIECloner::cloneDIE(const DWARFDie &InputDIE,
     }
   }
 
+  if (Unit.getOrigUnit().getVersion() >= 5 && !AttrInfo.AttrStrOffsetBaseSeen &&
+      Die->getTag() == dwarf::DW_TAG_compile_unit) {
+    // No DW_AT_str_offsets_base seen, add it to the DIE.
+    Die->addValue(DIEAlloc, dwarf::DW_AT_str_offsets_base,
+                  dwarf::DW_FORM_sec_offset, DIEInteger(8));
+    OutOffset += 4;
+  }
+
   DIEAbbrev NewAbbrev = Die->generateAbbrev();
   if (HasChildren)
     NewAbbrev.setChildrenFlag(dwarf::DW_CHILDREN_yes);
@@ -1840,8 +1867,19 @@ DIE *DWARFLinker::DIECloner::cloneDIE(const DWARFDie &InputDIE,
   Linker.assignAbbrev(NewAbbrev);
   Die->setAbbrevNumber(NewAbbrev.getNumber());
 
+  uint64_t AbbrevNumberSize = getULEB128Size(Die->getAbbrevNumber());
+
   // Add the size of the abbreviation number to the output offset.
-  OutOffset += getULEB128Size(Die->getAbbrevNumber());
+  OutOffset += AbbrevNumberSize;
+
+  // Update fixups with the size of the abbreviation number
+  for (AttributeLinkedOffsetFixup &F : AttributesFixups)
+    F.LinkedOffsetFixupVal += AbbrevNumberSize;
+
+  for (AttributeLinkedOffsetFixup &F : AttributesFixups)
+    ObjFile.Addresses->updateAndSaveValidRelocs(
+        Unit.getOrigUnit().getVersion() >= 5, Unit.getOrigUnit().getOffset(),
+        F.LinkedOffsetFixupVal, F.InputAttrStartOffset, F.InputAttrEndOffset);
 
   if (!HasChildren) {
     // Update our size.
@@ -1868,8 +1906,8 @@ DIE *DWARFLinker::DIECloner::cloneDIE(const DWARFDie &InputDIE,
 /// Patch the input object file relevant debug_ranges or debug_rnglists
 /// entries and emit them in the output file. Update the relevant attributes
 /// to point at the new entries.
-void DWARFLinker::generateUnitRanges(CompileUnit &Unit,
-                                     const DWARFFile &File) const {
+void DWARFLinker::generateUnitRanges(CompileUnit &Unit, const DWARFFile &File,
+                                     DebugDieValuePool &AddrPool) const {
   if (LLVM_UNLIKELY(Options.Update))
     return;
 
@@ -1922,14 +1960,14 @@ void DWARFLinker::generateUnitRanges(CompileUnit &Unit,
       }
 
       // Emit linked ranges.
-      TheDwarfEmitter->emitDwarfDebugRangeListFragment(Unit, LinkedRanges,
-                                                       AttributePatch);
+      TheDwarfEmitter->emitDwarfDebugRangeListFragment(
+          Unit, LinkedRanges, AttributePatch, AddrPool);
     }
 
     // Emit ranges for Unit AT_ranges attribute.
     if (UnitRngListAttribute.has_value())
       TheDwarfEmitter->emitDwarfDebugRangeListFragment(
-          Unit, LinkedFunctionRanges, *UnitRngListAttribute);
+          Unit, LinkedFunctionRanges, *UnitRngListAttribute, AddrPool);
 
     // Emit ranges footer.
     TheDwarfEmitter->emitDwarfDebugRangeListFooter(Unit, EndLabel);
@@ -2011,13 +2049,14 @@ void DWARFLinker::DIECloner::emitDebugAddrSection(
   if (DwarfVersion < 5)
     return;
 
-  if (AddrPool.Addrs.empty())
+  if (AddrPool.DieValues.empty())
     return;
 
   MCSymbol *EndLabel = Emitter->emitDwarfDebugAddrsHeader(Unit);
   patchAddrBase(*Unit.getOutputUnitDIE(),
                 DIEInteger(Emitter->getDebugAddrSectionSize()));
-  Emitter->emitDwarfDebugAddrs(AddrPool.Addrs, Unit.getOrigUnit().getAddressByteSize());
+  Emitter->emitDwarfDebugAddrs(AddrPool.DieValues,
+                               Unit.getOrigUnit().getAddressByteSize());
   Emitter->emitDwarfDebugAddrsFooter(Unit, EndLabel);
 }
 
@@ -2571,7 +2610,7 @@ uint64_t DWARFLinker::DIECloner::cloneAllCompileUnits(
       if (LLVM_UNLIKELY(Linker.Options.Update))
         continue;
 
-      Linker.generateUnitRanges(*CurrentUnit, File);
+      Linker.generateUnitRanges(*CurrentUnit, File, AddrPool);
 
       auto ProcessExpr = [&](SmallVectorImpl<uint8_t> &SrcBytes,
                              SmallVectorImpl<uint8_t> &OutBytes,
@@ -2617,69 +2656,6 @@ uint64_t DWARFLinker::DIECloner::cloneAllCompileUnits(
   return OutputDebugInfoSize - StartOutputDebugInfoSize;
 }
 
-bool DWARFLinker::emitPaperTrailWarnings(const DWARFFile &File,
-                                         OffsetsStringPool &StringPool) {
-
-  if (File.Warnings.empty())
-    return false;
-
-  DIE *CUDie = DIE::get(DIEAlloc, dwarf::DW_TAG_compile_unit);
-  CUDie->setOffset(11);
-  StringRef Producer;
-  StringRef WarningHeader;
-
-  switch (DwarfLinkerClientID) {
-  case DwarfLinkerClient::Dsymutil:
-    Producer = StringPool.internString("dsymutil");
-    WarningHeader = "dsymutil_warning";
-    break;
-
-  default:
-    Producer = StringPool.internString("dwarfopt");
-    WarningHeader = "dwarfopt_warning";
-    break;
-  }
-
-  StringRef FileName = StringPool.internString(File.FileName);
-  CUDie->addValue(DIEAlloc, dwarf::DW_AT_producer, dwarf::DW_FORM_strp,
-                  DIEInteger(StringPool.getStringOffset(Producer)));
-  DIEBlock *String = new (DIEAlloc) DIEBlock();
-  DIEBlocks.push_back(String);
-  for (auto &C : FileName)
-    String->addValue(DIEAlloc, dwarf::Attribute(0), dwarf::DW_FORM_data1,
-                     DIEInteger(C));
-  String->addValue(DIEAlloc, dwarf::Attribute(0), dwarf::DW_FORM_data1,
-                   DIEInteger(0));
-
-  CUDie->addValue(DIEAlloc, dwarf::DW_AT_name, dwarf::DW_FORM_string, String);
-  for (const auto &Warning : File.Warnings) {
-    DIE &ConstDie = CUDie->addChild(DIE::get(DIEAlloc, dwarf::DW_TAG_constant));
-    ConstDie.addValue(DIEAlloc, dwarf::DW_AT_name, dwarf::DW_FORM_strp,
-                      DIEInteger(StringPool.getStringOffset(WarningHeader)));
-    ConstDie.addValue(DIEAlloc, dwarf::DW_AT_artificial, dwarf::DW_FORM_flag,
-                      DIEInteger(1));
-    ConstDie.addValue(DIEAlloc, dwarf::DW_AT_const_value, dwarf::DW_FORM_strp,
-                      DIEInteger(StringPool.getStringOffset(Warning)));
-  }
-  unsigned Size = 4 /* FORM_strp */ + FileName.size() + 1 +
-                  File.Warnings.size() * (4 + 1 + 4) + 1 /* End of children */;
-  DIEAbbrev Abbrev = CUDie->generateAbbrev();
-  assignAbbrev(Abbrev);
-  CUDie->setAbbrevNumber(Abbrev.getNumber());
-  Size += getULEB128Size(Abbrev.getNumber());
-  // Abbreviation ordering needed for classic compatibility.
-  for (auto &Child : CUDie->children()) {
-    Abbrev = Child.generateAbbrev();
-    assignAbbrev(Abbrev);
-    Child.setAbbrevNumber(Abbrev.getNumber());
-    Size += getULEB128Size(Abbrev.getNumber());
-  }
-  CUDie->setSize(Size);
-  TheDwarfEmitter->emitPaperTrailWarningsDie(*CUDie);
-
-  return true;
-}
-
 void DWARFLinker::copyInvariantDebugSection(DWARFContext &Dwarf) {
   TheDwarfEmitter->emitSectionContents(Dwarf.getDWARFObj().getLocSection().Data,
                                        "debug_loc");
@@ -2731,6 +2707,7 @@ Error DWARFLinker::link() {
   // reproducibility.
   OffsetsStringPool DebugStrPool(StringsTranslator, true);
   OffsetsStringPool DebugLineStrPool(StringsTranslator, false);
+  DebugDieValuePool StringOffsetPool;
 
   // ODR Contexts for the optimize.
   DeclContextTree ODRContexts;
@@ -2743,9 +2720,6 @@ Error DWARFLinker::link() {
         outs() << "OBJECT FILE: " << OptContext.File.FileName << "\n";
     }
 
-    if (emitPaperTrailWarnings(OptContext.File, DebugStrPool))
-      continue;
-
     if (!OptContext.File.Dwarf)
       continue;
 
@@ -2780,12 +2754,12 @@ Error DWARFLinker::link() {
       continue;
     }
 
-    // In a first phase, just read in the debug info and load all clang modules.
+    // Clone all the clang modules with requires extracting the DIE units. We
+    // don't need the full debug info until the Analyze phase.
     OptContext.CompileUnits.reserve(
         OptContext.File.Dwarf->getNumCompileUnits());
-
     for (const auto &CU : OptContext.File.Dwarf->compile_units()) {
-      auto CUDie = CU->getUnitDIE(false);
+      auto CUDie = CU->getUnitDIE(/*ExtractUnitDIEOnly=*/true);
       if (Options.Verbose) {
         outs() << "Input compilation unit:";
         DIDumpOptions DumpOpts;
@@ -2797,7 +2771,7 @@ Error DWARFLinker::link() {
 
     for (auto &CU : OptContext.ModuleUnits) {
       if (Error Err = cloneModuleUnit(OptContext, CU, ODRContexts, DebugStrPool,
-                                      DebugLineStrPool))
+                                      DebugLineStrPool, StringOffsetPool))
         reportWarning(toString(std::move(Err)), CU.File);
     }
   }
@@ -2826,9 +2800,9 @@ Error DWARFLinker::link() {
       return;
 
     for (const auto &CU : Context.File.Dwarf->compile_units()) {
-      // The !isClangModuleRef condition effectively skips over fully resolved
-      // skeleton units.
-      auto CUDie = CU->getUnitDIE();
+      // Previously we only extracted the unit DIEs. We need the full debug info
+      // now.
+      auto CUDie = CU->getUnitDIE(/*ExtractUnitDIEOnly=*/false);
       std::string PCMFile = getPCMFile(CUDie, Options.ObjectPrefixMap);
 
       if (!CUDie || LLVM_UNLIKELY(Options.Update) ||
@@ -2894,7 +2868,7 @@ Error DWARFLinker::link() {
       SizeByObject[OptContext.File.FileName].Output =
           DIECloner(*this, TheDwarfEmitter.get(), OptContext.File, DIEAlloc,
                     OptContext.CompileUnits, Options.Update, DebugStrPool,
-                    DebugLineStrPool)
+                    DebugLineStrPool, StringOffsetPool)
               .cloneAllCompileUnits(*OptContext.File.Dwarf, OptContext.File,
                                     OptContext.File.Dwarf->isLittleEndian());
     }
@@ -2911,6 +2885,8 @@ Error DWARFLinker::link() {
     if (TheDwarfEmitter != nullptr) {
       TheDwarfEmitter->emitAbbrevs(Abbreviations, Options.TargetDWARFVersion);
       TheDwarfEmitter->emitStrings(DebugStrPool);
+      TheDwarfEmitter->emitStringOffsets(StringOffsetPool.DieValues,
+                                         Options.TargetDWARFVersion);
       TheDwarfEmitter->emitLineStrings(DebugLineStrPool);
       for (AccelTableKind TableKind : Options.AccelTables) {
         switch (TableKind) {
@@ -3027,6 +3003,7 @@ Error DWARFLinker::cloneModuleUnit(LinkContext &Context, RefModuleUnit &Unit,
                                    DeclContextTree &ODRContexts,
                                    OffsetsStringPool &DebugStrPool,
                                    OffsetsStringPool &DebugLineStrPool,
+                                   DebugDieValuePool &StringOffsetPool,
                                    unsigned Indent) {
   assert(Unit.Unit.get() != nullptr);
 
@@ -3053,7 +3030,7 @@ Error DWARFLinker::cloneModuleUnit(LinkContext &Context, RefModuleUnit &Unit,
   CompileUnits.emplace_back(std::move(Unit.Unit));
   assert(TheDwarfEmitter);
   DIECloner(*this, TheDwarfEmitter.get(), Unit.File, DIEAlloc, CompileUnits,
-            Options.Update, DebugStrPool, DebugLineStrPool)
+            Options.Update, DebugStrPool, DebugLineStrPool, StringOffsetPool)
       .cloneAllCompileUnits(*Unit.File.Dwarf, Unit.File,
                             Unit.File.Dwarf->isLittleEndian());
   return Error::success();
@@ -3062,11 +3039,13 @@ Error DWARFLinker::cloneModuleUnit(LinkContext &Context, RefModuleUnit &Unit,
 void DWARFLinker::verifyInput(const DWARFFile &File) {
   assert(File.Dwarf);
 
-  raw_ostream &os = Options.Verbose ? errs() : nulls();
+
+  std::string Buffer;
+  raw_string_ostream OS(Buffer);
   DIDumpOptions DumpOpts;
-  if (!File.Dwarf->verify(os, DumpOpts.noImplicitRecursion())) {
+  if (!File.Dwarf->verify(OS, DumpOpts.noImplicitRecursion())) {
     if (Options.InputVerificationHandler)
-      Options.InputVerificationHandler(File);
+      Options.InputVerificationHandler(File, OS.str());
   }
 }
 
diff --git a/llvm/lib/DWARFLinker/DWARFLinkerCompileUnit.cpp b/llvm/lib/DWARFLinker/DWARFLinkerCompileUnit.cpp
index add0d94da73f..06559bc38c86 100644
--- a/llvm/lib/DWARFLinker/DWARFLinkerCompileUnit.cpp
+++ b/llvm/lib/DWARFLinker/DWARFLinkerCompileUnit.cpp
@@ -97,8 +97,10 @@ void CompileUnit::markEverythingAsKept() {
         ++NextIt;
 
         switch (It->getCode()) {
+        case dwarf::DW_OP_const2u:
         case dwarf::DW_OP_const4u:
         case dwarf::DW_OP_const8u:
+        case dwarf::DW_OP_const2s:
         case dwarf::DW_OP_const4s:
         case dwarf::DW_OP_const8s:
           if (NextIt == Expression.end() ||
diff --git a/llvm/lib/DWARFLinker/DWARFStreamer.cpp b/llvm/lib/DWARFLinker/DWARFStreamer.cpp
index fbd89dcf1ca1..cd649c328ed9 100644
--- a/llvm/lib/DWARFLinker/DWARFStreamer.cpp
+++ b/llvm/lib/DWARFLinker/DWARFStreamer.cpp
@@ -234,18 +234,6 @@ void DwarfStreamer::emitSectionContents(StringRef SecData, StringRef SecName) {
   }
 }
 
-/// Emit DIE containing warnings.
-void DwarfStreamer::emitPaperTrailWarningsDie(DIE &Die) {
-  switchToDebugInfoSection(/* Version */ 2);
-  auto &Asm = getAsmPrinter();
-  Asm.emitInt32(11 + Die.getSize() - 4);
-  Asm.emitInt16(2);
-  Asm.emitInt32(0);
-  Asm.emitInt8(MC->getTargetTriple().isArch64Bit() ? 8 : 4);
-  DebugInfoSectionSize += 11;
-  emitDIE(Die);
-}
-
 /// Emit the debug_str section stored in \p Pool.
 void DwarfStreamer::emitStrings(const NonRelocatableStringpool &Pool) {
   Asm->OutStreamer->switchSection(MOFI->getDwarfStrSection());
@@ -258,6 +246,39 @@ void DwarfStreamer::emitStrings(const NonRelocatableStringpool &Pool) {
   }
 }
 
+/// Emit the debug string offset table described by \p StringOffsets into the
+/// .debug_str_offsets table.
+void DwarfStreamer::emitStringOffsets(
+    const SmallVector<uint64_t> &StringOffsets, uint16_t TargetDWARFVersion) {
+
+  if (TargetDWARFVersion < 5 || StringOffsets.empty())
+    return;
+
+  Asm->OutStreamer->switchSection(MOFI->getDwarfStrOffSection());
+
+  MCSymbol *BeginLabel = Asm->createTempSymbol("Bdebugstroff");
+  MCSymbol *EndLabel = Asm->createTempSymbol("Edebugstroff");
+
+  // Length.
+  Asm->emitLabelDifference(EndLabel, BeginLabel, sizeof(uint32_t));
+  Asm->OutStreamer->emitLabel(BeginLabel);
+  StrOffsetSectionSize += sizeof(uint32_t);
+
+  // Version.
+  MS->emitInt16(5);
+  StrOffsetSectionSize += sizeof(uint16_t);
+
+  // Padding.
+  MS->emitInt16(0);
+  StrOffsetSectionSize += sizeof(uint16_t);
+
+  for (auto Off : StringOffsets) {
+    Asm->OutStreamer->emitInt32(Off);
+    StrOffsetSectionSize += sizeof(uint32_t);
+  }
+  Asm->OutStreamer->emitLabel(EndLabel);
+}
+
 /// Emit the debug_line_str section stored in \p Pool.
 void DwarfStreamer::emitLineStrings(const NonRelocatableStringpool &Pool) {
   Asm->OutStreamer->switchSection(MOFI->getDwarfLineStrSection());
@@ -270,14 +291,13 @@ void DwarfStreamer::emitLineStrings(const NonRelocatableStringpool &Pool) {
   }
 }
 
-void DwarfStreamer::emitDebugNames(
-    AccelTable<DWARF5AccelTableStaticData> &Table) {
+void DwarfStreamer::emitDebugNames(DWARF5AccelTable &Table) {
   if (EmittedUnits.empty())
     return;
 
   // Build up data structures needed to emit this section.
-  std::vector<MCSymbol *> CompUnits;
-  DenseMap<unsigned, size_t> UniqueIdToCuMap;
+  std::vector<std::variant<MCSymbol *, uint64_t>> CompUnits;
+  DenseMap<unsigned, unsigned> UniqueIdToCuMap;
   unsigned Id = 0;
   for (auto &CU : EmittedUnits) {
     CompUnits.push_back(CU.LabelBegin);
@@ -286,10 +306,19 @@ void DwarfStreamer::emitDebugNames(
   }
 
   Asm->OutStreamer->switchSection(MOFI->getDwarfDebugNamesSection());
+  dwarf::Form Form = DIEInteger::BestForm(/*IsSigned*/ false,
+                                          (uint64_t)UniqueIdToCuMap.size() - 1);
+  /// llvm-dwarfutil doesn't support type units + .debug_names right now.
+  // FIXME: add support for type units + .debug_names. For now the behavior is
+  // unsuported.
   emitDWARF5AccelTable(
       Asm.get(), Table, CompUnits,
-      [&UniqueIdToCuMap](const DWARF5AccelTableStaticData &Entry) {
-        return UniqueIdToCuMap[Entry.getCUIndex()];
+      [&](const DWARF5AccelTableData &Entry)
+          -> std::optional<DWARF5AccelTable::UnitIndexAndEncoding> {
+        if (UniqueIdToCuMap.size() > 1)
+          return {{UniqueIdToCuMap[Entry.getUnitID()],
+                   {dwarf::DW_IDX_compile_unit, Form}}};
+        return std::nullopt;
       });
 }
 
@@ -455,13 +484,13 @@ DwarfStreamer::emitDwarfDebugRangeListHeader(const CompileUnit &Unit) {
 
 void DwarfStreamer::emitDwarfDebugRangeListFragment(
     const CompileUnit &Unit, const AddressRanges &LinkedRanges,
-    PatchLocation Patch) {
+    PatchLocation Patch, DebugDieValuePool &AddrPool) {
   if (Unit.getOrigUnit().getVersion() < 5) {
     emitDwarfDebugRangesTableFragment(Unit, LinkedRanges, Patch);
     return;
   }
 
-  emitDwarfDebugRngListsTableFragment(Unit, LinkedRanges, Patch);
+  emitDwarfDebugRngListsTableFragment(Unit, LinkedRanges, Patch, AddrPool);
 }
 
 void DwarfStreamer::emitDwarfDebugRangeListFooter(const CompileUnit &Unit,
@@ -478,25 +507,35 @@ void DwarfStreamer::emitDwarfDebugRangeListFooter(const CompileUnit &Unit,
 
 void DwarfStreamer::emitDwarfDebugRngListsTableFragment(
     const CompileUnit &Unit, const AddressRanges &LinkedRanges,
-    PatchLocation Patch) {
+    PatchLocation Patch, DebugDieValuePool &AddrPool) {
   Patch.set(RngListsSectionSize);
 
   // Make .debug_rnglists to be current section.
   MS->switchSection(MC->getObjectFileInfo()->getDwarfRnglistsSection());
-
-  unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
+  std::optional<uint64_t> BaseAddress;
 
   for (const AddressRange &Range : LinkedRanges) {
+
+    if (!BaseAddress) {
+      BaseAddress = Range.start();
+
+      // Emit base address.
+      MS->emitInt8(dwarf::DW_RLE_base_addressx);
+      RngListsSectionSize += 1;
+      RngListsSectionSize +=
+          MS->emitULEB128IntValue(AddrPool.getValueIndex(*BaseAddress));
+    }
+
     // Emit type of entry.
-    MS->emitInt8(dwarf::DW_RLE_start_length);
+    MS->emitInt8(dwarf::DW_RLE_offset_pair);
     RngListsSectionSize += 1;
 
-    // Emit start address.
-    MS->emitIntValue(Range.start(), AddressSize);
-    RngListsSectionSize += AddressSize;
+    // Emit start offset relative to base address.
+    RngListsSectionSize +=
+        MS->emitULEB128IntValue(Range.start() - *BaseAddress);
 
-    // Emit length of the range.
-    RngListsSectionSize += MS->emitULEB128IntValue(Range.end() - Range.start());
+    // Emit end offset relative to base address.
+    RngListsSectionSize += MS->emitULEB128IntValue(Range.end() - *BaseAddress);
   }
 
   // Emit the terminator entry.
@@ -544,7 +583,7 @@ MCSymbol *DwarfStreamer::emitDwarfDebugLocListHeader(const CompileUnit &Unit) {
 void DwarfStreamer::emitDwarfDebugLocListFragment(
     const CompileUnit &Unit,
     const DWARFLocationExpressionsVector &LinkedLocationExpression,
-    PatchLocation Patch, DebugAddrPool &AddrPool) {
+    PatchLocation Patch, DebugDieValuePool &AddrPool) {
   if (Unit.getOrigUnit().getVersion() < 5) {
     emitDwarfDebugLocTableFragment(Unit, LinkedLocationExpression, Patch);
     return;
@@ -662,7 +701,7 @@ void DwarfStreamer::emitDwarfDebugAddrsFooter(const CompileUnit &Unit,
 void DwarfStreamer::emitDwarfDebugLocListsTableFragment(
     const CompileUnit &Unit,
     const DWARFLocationExpressionsVector &LinkedLocationExpression,
-    PatchLocation Patch, DebugAddrPool &AddrPool) {
+    PatchLocation Patch, DebugDieValuePool &AddrPool) {
   Patch.set(LocListsSectionSize);
 
   // Make .debug_loclists the current section.
@@ -681,7 +720,7 @@ void DwarfStreamer::emitDwarfDebugLocListsTableFragment(
         MS->emitInt8(dwarf::DW_LLE_base_addressx);
         LocListsSectionSize += 1;
         LocListsSectionSize +=
-            MS->emitULEB128IntValue(AddrPool.getAddrIndex(*BaseAddress));
+            MS->emitULEB128IntValue(AddrPool.getValueIndex(*BaseAddress));
       }
 
       // Emit type of entry.