Use delegation instead of inheritance

[• rafael]

Summary

This changes DwarfContext to delegate to DwarfObj instead of having pure virtual methods.

With this DwarfContextInMemory is a trivial class that uses a new implementation of a DwarfObj which can be in a .cpp file.

This is more verbose than I was hopping for, but does allow lld to just implement a DwarfObj. Let me know if you think this is too verbose and I can subclass DwarfContext in lld instead.

[• rafael]

Use dummy values instead of unreachable.

[dblaikie]

Might be helpful to have a bit of a summary about what's changing here, separate from looking at all the source manually - what operations stayed in DWARFContext{,InMemory} versus those that moved out into DWARFObject?

Do all the operations need wrappers in DWARFContext, or could many of those be removed because they're probably only used internally within DWARFContext & could be replaced with "Obj->thing" instead? (though that's more refactoring/churn, I realize)

include/llvm/DebugInfo/DWARF/DWARFContext.h

56

Why do these all need default implementations? Guessing there's a reason they're not pure virtual? Though it seems like it'd make using this class more difficult if there are implicit contracts about which subset of operations are implemented and which ones are not?

[• rafael]

Inline trivial functions.

[dblaikie]

Generally looks good to me - few bits to be tidied up, etc.
Haven't looked meticulously closely at the bits of code that moved around, but I assume there wasn't anything particularly novel there.

Might be worth waiting for a few more eyes, but doesn't seem too crazy.

include/llvm/DebugInfo/DWARF/DWARFContext.h

56

Pull this out into a separate file, probably? (& maybe even pull DWARFObjInMemory into a separate file too - we do end up with some pretty big/glommy headers)

(no need to do this pre-emptively, if you want to wait to see how the design choices shake out)

60

default?

91–95

Given that DWARFSection is now only StringRef - why not return by value & return "" like the rest? (& I sitll don't know whether DWARFSection needs to exist at all if it's only a wrapper around StringRef - it makes this whole class look a bit random/arbitrary between some functions returning StringRef for a section, and others returning const DWARFSection&)

156

Why is this non-owning and DWARFContextInMemory owning?

Are tehre any other implementations of DWARFContext (other than DWARFContextInMemory) or should we just do away with the abstraction if it's unused?

include/llvm/DebugInfo/DWARF/DWARFSection.h

18–24

What's the reason for this split? Is DWARFSection much use if it's a straight up wrapper around StringRef?

[• rafael]

Move some code to another header.

[• rafael]

Move DWARFContextInMemory to a .cpp file I will completely delete it tomorrow.

[• rafael]

Delete DWARFContextInMemory.

[• rafael]

Rebased.

[dblaikie]

include/llvm/DebugInfo/DWARF/DWARFObj.h

24 ↗

(On Diff #107377)

I'd wonder about the name - DWARFObject? DWARFObjectSections?

unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp

2186 ↗

(On Diff #107377)

"*Obj.get()" can probably be "*Obj"? (similarly above)

[• espindola]

308543

include/llvm/DebugInfo/DWARF/DWARFContext.h

 class MemoryBuffer;
 class raw_ostream;
 
+// This is responsible for low level access to the object file. It
+// knows how to find the required sections and compute relocated
+// values.
+// The default implementations of the get<Section> methods return dummy values.
+// This is to allow clients that only need some of those to implement just the
+// ones they need. We can't use unreachable for as many cases because the parser
+// implementation is eager and will call some of these methods even if the
+// result is not used.
+class DWARFObj {
+  DWARFSection Dummy;
+
+public:
+  virtual ~DWARFObj() {}
+  virtual StringRef getFileName() const { llvm_unreachable("unimplemented"); }
+  virtual bool isLittleEndian() const = 0;
+  virtual uint8_t getAddressSize() const { llvm_unreachable("unimplemented"); }
+  virtual const DWARFSection &getInfoSection() const { return Dummy; }
+  virtual void
+  forEachTypesSections(function_ref<void(const DWARFSection &)> F) const {}
+  virtual StringRef getAbbrevSection() const { return ""; }
+  virtual const DWARFSection &getLocSection() const { return Dummy; }
+  virtual StringRef getARangeSection() const { return ""; }
+  virtual StringRef getDebugFrameSection() const { return ""; }
+  virtual StringRef getEHFrameSection() const { return ""; }
+  virtual const DWARFSection &getLineSection() const { return Dummy; }
+  virtual StringRef getStringSection() const { return ""; }
+  virtual const DWARFSection &getRangeSection() const { return Dummy; }
+  virtual StringRef getMacinfoSection() const { return ""; }
+  virtual StringRef getPubNamesSection() const { return ""; }
+  virtual StringRef getPubTypesSection() const { return ""; }
+  virtual StringRef getGnuPubNamesSection() const { return ""; }
+  virtual StringRef getGnuPubTypesSection() const { return ""; }
+  virtual const DWARFSection &getStringOffsetSection() const { return Dummy; }
+  virtual const DWARFSection &getInfoDWOSection() const { return Dummy; }
+  virtual void
+  forEachTypesDWOSections(function_ref<void(const DWARFSection &)> F) const {}
+  virtual StringRef getAbbrevDWOSection() const { return ""; }
+  virtual const DWARFSection &getLineDWOSection() const { return Dummy; }
+  virtual const DWARFSection &getLocDWOSection() const { return Dummy; }
+  virtual StringRef getStringDWOSection() const { return ""; }
+  virtual const DWARFSection &getStringOffsetDWOSection() const {
+    return Dummy;
+  }
+  virtual const DWARFSection &getRangeDWOSection() const { return Dummy; }
+  virtual const DWARFSection &getAddrSection() const { return Dummy; }
+  virtual const DWARFSection &getAppleNamesSection() const { return Dummy; }
+  virtual const DWARFSection &getAppleTypesSection() const { return Dummy; }
+  virtual const DWARFSection &getAppleNamespacesSection() const {
+    return Dummy;
+  }
+  virtual const DWARFSection &getAppleObjCSection() const { return Dummy; }
+  virtual StringRef getCUIndexSection() const { return ""; }
+  virtual StringRef getGdbIndexSection() const { return ""; }
+  virtual StringRef getTUIndexSection() const { return ""; }
+  virtual Optional<RelocAddrEntry> find(const DWARFSection &Sec,
+                                        uint64_t Pos) const = 0;
+};
+
 /// DWARFContext
 /// This data structure is the top level entity that deals with dwarf debug
-/// information parsing. The actual data is supplied through pure virtual
-/// methods that a concrete implementation provides.
+/// information parsing. The actual data is supplied through DWARFObj.
 class DWARFContext : public DIContext {
   DWARFUnitSection<DWARFCompileUnit> CUs;
   std::deque<DWARFUnitSection<DWARFTypeUnit>> TUs;

   /// and store them in DWOTUs.
   void parseDWOTypeUnits();
 
+protected:
+  const DWARFObj &DObj;
+
 public:
-  DWARFContext() : DIContext(CK_DWARF) {}
+  DWARFContext(const DWARFObj &DObj) : DIContext(CK_DWARF), DObj(DObj) {}
   DWARFContext(DWARFContext &) = delete;
   DWARFContext &operator=(DWARFContext &) = delete;
 
+  const DWARFObj &getDWARFObj() const { return DObj; }
+
   static bool classof(const DIContext *DICtx) {
     return DICtx->getKind() == CK_DWARF;
   }

   DIInliningInfo getInliningInfoForAddress(uint64_t Address,
       DILineInfoSpecifier Specifier = DILineInfoSpecifier()) override;
 
-  virtual StringRef getFileName() const = 0;
-  virtual bool isLittleEndian() const = 0;
-  virtual uint8_t getAddressSize() const = 0;
-  virtual const DWARFSection &getInfoSection() = 0;
-  virtual void forEachTypesSections(function_ref<void(DWARFSection &)> F) = 0;
-  virtual StringRef getAbbrevSection() = 0;
-  virtual const DWARFSection &getLocSection() = 0;
-  virtual StringRef getARangeSection() = 0;
-  virtual StringRef getDebugFrameSection() = 0;
-  virtual StringRef getEHFrameSection() = 0;
-  virtual const DWARFSection &getLineSection() = 0;
-  virtual StringRef getStringSection() = 0;
-  virtual const DWARFSection& getRangeSection() = 0;
-  virtual StringRef getMacinfoSection() = 0;
-  virtual StringRef getPubNamesSection() = 0;
-  virtual StringRef getPubTypesSection() = 0;
-  virtual StringRef getGnuPubNamesSection() = 0;
-  virtual StringRef getGnuPubTypesSection() = 0;
-
-  /// DWARF v5
-  /// @{
-  virtual const DWARFSection &getStringOffsetSection() = 0;
-  /// @}
-
-  // Sections for DWARF5 split dwarf proposal.
-  virtual const DWARFSection &getInfoDWOSection() = 0;
-  virtual void
-  forEachTypesDWOSections(function_ref<void(DWARFSection &)> F) = 0;
-  virtual StringRef getAbbrevDWOSection() = 0;
-  virtual const DWARFSection &getLineDWOSection() = 0;
-  virtual const DWARFSection &getLocDWOSection() = 0;
-  virtual StringRef getStringDWOSection() = 0;
-  virtual const DWARFSection &getStringOffsetDWOSection() = 0;
-  virtual const DWARFSection &getRangeDWOSection() = 0;
-  virtual const DWARFSection &getAddrSection() = 0;
-  virtual const DWARFSection& getAppleNamesSection() = 0;
-  virtual const DWARFSection& getAppleTypesSection() = 0;
-  virtual const DWARFSection& getAppleNamespacesSection() = 0;
-  virtual const DWARFSection& getAppleObjCSection() = 0;
-  virtual StringRef getCUIndexSection() = 0;
-  virtual StringRef getGdbIndexSection() = 0;
-  virtual StringRef getTUIndexSection() = 0;
-
+  bool isLittleEndian() const { return DObj.isLittleEndian(); }
   static bool isSupportedVersion(unsigned version) {
     return version == 2 || version == 3 || version == 4 || version == 5;
   }

 /// DWARFContext. It assumes all content is available in memory and stores
 /// pointers to it.
 class DWARFContextInMemory : public DWARFContext {
-  virtual void anchor();
-
-  using TypeSectionMap = MapVector<object::SectionRef, DWARFSection,
-                                   std::map<object::SectionRef, unsigned>>;
-
-  StringRef FileName;
-  bool IsLittleEndian;
-  uint8_t AddressSize;
-  DWARFSection InfoSection;
-  TypeSectionMap TypesSections;
-  StringRef AbbrevSection;
-  DWARFSection LocSection;
-  StringRef ARangeSection;
-  StringRef DebugFrameSection;
-  StringRef EHFrameSection;
-  DWARFSection LineSection;
-  StringRef StringSection;
-  DWARFSection RangeSection;
-  StringRef MacinfoSection;
-  StringRef PubNamesSection;
-  StringRef PubTypesSection;
-  StringRef GnuPubNamesSection;
-  StringRef GnuPubTypesSection;
-
-  /// DWARF v5
-  /// @{
-  DWARFSection StringOffsetSection;
-  /// @}
-
-  // Sections for DWARF5 split dwarf proposal.
-  DWARFSection InfoDWOSection;
-  TypeSectionMap TypesDWOSections;
-  StringRef AbbrevDWOSection;
-  DWARFSection LineDWOSection;
-  DWARFSection LocDWOSection;
-  StringRef StringDWOSection;
-  DWARFSection StringOffsetDWOSection;
-  DWARFSection RangeDWOSection;
-  DWARFSection AddrSection;
-  DWARFSection AppleNamesSection;
-  DWARFSection AppleTypesSection;
-  DWARFSection AppleNamespacesSection;
-  DWARFSection AppleObjCSection;
-  StringRef CUIndexSection;
-  StringRef GdbIndexSection;
-  StringRef TUIndexSection;
-
-  SmallVector<SmallString<32>, 4> UncompressedSections;
-
-  DWARFSection *mapNameToDWARFSection(StringRef Name);
-  StringRef *mapSectionToMember(StringRef Name);
-
-  /// If Sec is compressed section, decompresses and updates its contents
-  /// provided by Data. Otherwise leaves it unchanged.
-  Error maybeDecompress(const object::SectionRef &Sec, StringRef Name,
-                        StringRef &Data);
+  std::unique_ptr<const DWARFObj> DObjP;
 
   /// Function used to handle default error reporting policy. Prints a error
   /// message and returns Continue, so DWARF context ignores the error.

                        uint8_t AddrSize,
                        bool isLittleEndian = sys::IsLittleEndianHost);
 
-  StringRef getFileName() const override { return FileName; }
-  bool isLittleEndian() const override { return IsLittleEndian; }
-  uint8_t getAddressSize() const override { return AddressSize; }
-  const DWARFSection &getInfoSection() override { return InfoSection; }
-  void forEachTypesSections(function_ref<void(DWARFSection &)> F) override {
-    for (auto &P : TypesSections)
-      F(P.second);
-  }
-  StringRef getAbbrevSection() override { return AbbrevSection; }
-  const DWARFSection &getLocSection() override { return LocSection; }
-  StringRef getARangeSection() override { return ARangeSection; }
-  StringRef getDebugFrameSection() override { return DebugFrameSection; }
-  StringRef getEHFrameSection() override { return EHFrameSection; }
-  const DWARFSection &getLineSection() override { return LineSection; }
-  StringRef getStringSection() override { return StringSection; }
-  const DWARFSection &getRangeSection() override { return RangeSection; }
-  StringRef getMacinfoSection() override { return MacinfoSection; }
-  StringRef getPubNamesSection() override { return PubNamesSection; }
-  StringRef getPubTypesSection() override { return PubTypesSection; }
-  StringRef getGnuPubNamesSection() override { return GnuPubNamesSection; }
-  StringRef getGnuPubTypesSection() override { return GnuPubTypesSection; }
-  const DWARFSection& getAppleNamesSection() override { return AppleNamesSection; }
-  const DWARFSection& getAppleTypesSection() override { return AppleTypesSection; }
-  const DWARFSection& getAppleNamespacesSection() override { return AppleNamespacesSection; }
-  const DWARFSection& getAppleObjCSection() override { return AppleObjCSection; }
-
-  // DWARF v5
-  const DWARFSection &getStringOffsetSection() override {
-    return StringOffsetSection;
-  }
-
-  // Sections for DWARF5 split dwarf proposal.
-  const DWARFSection &getInfoDWOSection() override { return InfoDWOSection; }
-
-  void forEachTypesDWOSections(function_ref<void(DWARFSection &)> F) override {
-    for (auto &P : TypesDWOSections)
-      F(P.second);
-  }
-
-  StringRef getAbbrevDWOSection() override { return AbbrevDWOSection; }
-  const DWARFSection &getLineDWOSection() override { return LineDWOSection; }
-  const DWARFSection &getLocDWOSection() override { return LocDWOSection; }
-  StringRef getStringDWOSection() override { return StringDWOSection; }
-
-  const DWARFSection &getStringOffsetDWOSection() override {
-    return StringOffsetDWOSection;
-  }
-
-  const DWARFSection &getRangeDWOSection() override { return RangeDWOSection; }
-
-  const DWARFSection &getAddrSection() override { return AddrSection; }
-
-  StringRef getCUIndexSection() override { return CUIndexSection; }
-  StringRef getGdbIndexSection() override { return GdbIndexSection; }
-  StringRef getTUIndexSection() override { return TUIndexSection; }
 };
 
 } // end namespace llvm

include/llvm/DebugInfo/DWARF/DWARFDataExtractor.h

 #include "llvm/Support/DataExtractor.h"
 
 namespace llvm {
+class DWARFObj;
 
 /// A DataExtractor (typically for an in-memory copy of an object-file section)
 /// plus a relocation map for that section, if there is one.
 class DWARFDataExtractor : public DataExtractor {
-  const RelocAddrMap *RelocMap = nullptr;
+  const DWARFObj *Obj = nullptr;
+  const DWARFSection *Section = nullptr;
+
 public:
   /// Constructor for the normal case of extracting data from a DWARF section.
   /// The DWARFSection's lifetime must be at least as long as the extractor's.
-  DWARFDataExtractor(const DWARFSection &Section, bool IsLittleEndian,
-                     uint8_t AddressSize)
-    : DataExtractor(Section.Data, IsLittleEndian, AddressSize),
-      RelocMap(&Section.Relocs) {}
+  DWARFDataExtractor(const DWARFObj &Obj, const DWARFSection &Section,
+                     bool IsLittleEndian, uint8_t AddressSize)
+      : DataExtractor(Section.Data, IsLittleEndian, AddressSize), Obj(&Obj),
+        Section(&Section) {}
 
   /// Constructor for cases when there are no relocations.
   DWARFDataExtractor(StringRef Data, bool IsLittleEndian, uint8_t AddressSize)

include/llvm/DebugInfo/DWARF/DWARFSection.h

 
 struct DWARFSection {
   StringRef Data;
+};
+
+struct DWARFSectionMap final : public DWARFSection {
   RelocAddrMap Relocs;
 };
 

include/llvm/DebugInfo/DWARF/DWARFUnit.h

   bool getAddrOffsetSectionItem(uint32_t Index, uint64_t &Result) const;
   bool getStringOffsetSectionItem(uint32_t Index, uint64_t &Result) const;
 
-  DWARFDataExtractor getDebugInfoExtractor() const {
-    return DWARFDataExtractor(InfoSection, isLittleEndian,
-                              getAddressByteSize());
-  }
+  DWARFDataExtractor getDebugInfoExtractor() const;
 
   DataExtractor getStringExtractor() const {
     return DataExtractor(StringSection, false, 0);
   }
 
-  const RelocAddrMap *getRelocMap() const { return &InfoSection.Relocs; }
-  const RelocAddrMap &getStringOffsetsRelocMap() const {
-    return StringOffsetSection.Relocs;
-  }
 
   bool extract(DataExtractor debug_info, uint32_t* offset_ptr);
 

lib/DebugInfo/DWARF/DWARFContext.cpp

 using FunctionNameKind = DILineInfoSpecifier::FunctionNameKind;
 
 static void dumpAccelSection(raw_ostream &OS, StringRef Name,
-                             const DWARFSection& Section, StringRef StringSection,
-                             bool LittleEndian) {
-  DWARFDataExtractor AccelSection(Section, LittleEndian, 0);
+                             const DWARFObj &Obj, const DWARFSection &Section,
+                             StringRef StringSection, bool LittleEndian) {
+  DWARFDataExtractor AccelSection(Obj, Section, LittleEndian, 0);
   DataExtractor StrData(StringSection, LittleEndian, 0);
   OS << "\n." << Name << " contents:\n";
   DWARFAcceleratorTable Accel(AccelSection, StrData);

 
 static void
 dumpDWARFv5StringOffsetsSection(raw_ostream &OS, StringRef SectionName,
+                                const DWARFObj &Obj,
                                 const DWARFSection &StringOffsetsSection,
                                 StringRef StringSection, bool LittleEndian) {
-  DWARFDataExtractor StrOffsetExt(StringOffsetsSection, LittleEndian, 0);
+  DWARFDataExtractor StrOffsetExt(Obj, StringOffsetsSection, LittleEndian, 0);
   uint32_t Offset = 0;
   uint64_t SectionSize = StringOffsetsSection.Data.size();
 

 // monolithic series of string offsets, as generated by the pre-DWARF v5
 // implementation of split DWARF.
 static void dumpStringOffsetsSection(raw_ostream &OS, StringRef SectionName,
+                                     const DWARFObj &Obj,
                                      const DWARFSection &StringOffsetsSection,
                                      StringRef StringSection, bool LittleEndian,
                                      unsigned MaxVersion) {

   // we assume that the section is formatted like a DWARF v5 string offsets
   // section.
   if (MaxVersion >= 5)
-    dumpDWARFv5StringOffsetsSection(OS, SectionName, StringOffsetsSection,
+    dumpDWARFv5StringOffsetsSection(OS, SectionName, Obj, StringOffsetsSection,
                                     StringSection, LittleEndian);
   else {
     DataExtractor strOffsetExt(StringOffsetsSection.Data, LittleEndian, 0);

   uint32_t offset = 0;
   if (DumpType == DIDT_All || DumpType == DIDT_Aranges) {
     OS << "\n.debug_aranges contents:\n";
-    DataExtractor arangesData(getARangeSection(), isLittleEndian(), 0);
+    DataExtractor arangesData(DObj.getARangeSection(), isLittleEndian(), 0);
     DWARFDebugArangeSet set;
     while (set.extract(arangesData, &offset))
       set.dump(OS);

       if (!CUDIE)
         continue;
       if (auto StmtOffset = toSectionOffset(CUDIE.find(DW_AT_stmt_list))) {
-        DWARFDataExtractor lineData(getLineSection(), isLittleEndian(),
-                                    savedAddressByteSize);
+        DWARFDataExtractor lineData(DObj, DObj.getLineSection(),
+                                    isLittleEndian(), savedAddressByteSize);
         DWARFDebugLine::LineTable LineTable;
         uint32_t Offset = *StmtOffset;
         LineTable.parse(lineData, &Offset);

   if (DumpType == DIDT_All || DumpType == DIDT_LineDwo) {
     OS << "\n.debug_line.dwo contents:\n";
     unsigned stmtOffset = 0;
-    DWARFDataExtractor lineData(getLineDWOSection(), isLittleEndian(),
-                                savedAddressByteSize);
+    DWARFDataExtractor lineData(DObj, DObj.getLineDWOSection(),
+                                isLittleEndian(), savedAddressByteSize);
     DWARFDebugLine::LineTable LineTable;
     while (LineTable.Prologue.parse(lineData, &stmtOffset)) {
       LineTable.dump(OS);

 
   if (DumpType == DIDT_All || DumpType == DIDT_Str) {
     OS << "\n.debug_str contents:\n";
-    DataExtractor strData(getStringSection(), isLittleEndian(), 0);
+    DataExtractor strData(DObj.getStringSection(), isLittleEndian(), 0);
     offset = 0;
     uint32_t strOffset = 0;
     while (const char *s = strData.getCStr(&offset)) {

   }
 
   if ((DumpType == DIDT_All || DumpType == DIDT_StrDwo) &&
-      !getStringDWOSection().empty()) {
+      !DObj.getStringDWOSection().empty()) {
     OS << "\n.debug_str.dwo contents:\n";
-    DataExtractor strDWOData(getStringDWOSection(), isLittleEndian(), 0);
+    DataExtractor strDWOData(DObj.getStringDWOSection(), isLittleEndian(), 0);
     offset = 0;
     uint32_t strDWOOffset = 0;
     while (const char *s = strDWOData.getCStr(&offset)) {

     // sizes, but for simplicity we just use the address byte size of the last
     // compile unit (there is no easy and fast way to associate address range
     // list and the compile unit it describes).
-    DWARFDataExtractor rangesData(getRangeSection(), isLittleEndian(),
-                                  savedAddressByteSize);
+    DWARFDataExtractor rangesData(DObj, DObj.getRangeSection(),
+                                  isLittleEndian(), savedAddressByteSize);
     offset = 0;
     DWARFDebugRangeList rangeList;
     while (rangeList.extract(rangesData, &offset))

   }
 
   if (DumpType == DIDT_All || DumpType == DIDT_Pubnames)
-    DWARFDebugPubTable(getPubNamesSection(), isLittleEndian(), false)
+    DWARFDebugPubTable(DObj.getPubNamesSection(), isLittleEndian(), false)
         .dump("debug_pubnames", OS);
 
   if (DumpType == DIDT_All || DumpType == DIDT_Pubtypes)
-    DWARFDebugPubTable(getPubTypesSection(), isLittleEndian(), false)
+    DWARFDebugPubTable(DObj.getPubTypesSection(), isLittleEndian(), false)
         .dump("debug_pubtypes", OS);
 
   if (DumpType == DIDT_All || DumpType == DIDT_GnuPubnames)
-    DWARFDebugPubTable(getGnuPubNamesSection(), isLittleEndian(),
+    DWARFDebugPubTable(DObj.getGnuPubNamesSection(), isLittleEndian(),
                        true /* GnuStyle */)
         .dump("debug_gnu_pubnames", OS);
 
   if (DumpType == DIDT_All || DumpType == DIDT_GnuPubtypes)
-    DWARFDebugPubTable(getGnuPubTypesSection(), isLittleEndian(),
+    DWARFDebugPubTable(DObj.getGnuPubTypesSection(), isLittleEndian(),
                        true /* GnuStyle */)
         .dump("debug_gnu_pubtypes", OS);
 
   if (DumpType == DIDT_All || DumpType == DIDT_StrOffsets)
-    dumpStringOffsetsSection(OS, "debug_str_offsets", getStringOffsetSection(),
-                             getStringSection(), isLittleEndian(),
-                             getMaxVersion());
+    dumpStringOffsetsSection(
+        OS, "debug_str_offsets", DObj, DObj.getStringOffsetSection(),
+        DObj.getStringSection(), isLittleEndian(), getMaxVersion());
 
   if (DumpType == DIDT_All || DumpType == DIDT_StrOffsetsDwo) {
-    dumpStringOffsetsSection(OS, "debug_str_offsets.dwo",
-                             getStringOffsetDWOSection(), getStringDWOSection(),
-                             isLittleEndian(), getMaxVersion());
+    dumpStringOffsetsSection(
+        OS, "debug_str_offsets.dwo", DObj, DObj.getStringOffsetDWOSection(),
+        DObj.getStringDWOSection(), isLittleEndian(), getMaxVersion());
   }
 
   if ((DumpType == DIDT_All || DumpType == DIDT_GdbIndex) &&
-      !getGdbIndexSection().empty()) {
+      !DObj.getGdbIndexSection().empty()) {
     OS << "\n.gnu_index contents:\n";
     getGdbIndex().dump(OS);
   }
 
   if (DumpType == DIDT_All || DumpType == DIDT_AppleNames)
-    dumpAccelSection(OS, "apple_names", getAppleNamesSection(),
-                     getStringSection(), isLittleEndian());
+    dumpAccelSection(OS, "apple_names", DObj, DObj.getAppleNamesSection(),
+                     DObj.getStringSection(), isLittleEndian());
 
   if (DumpType == DIDT_All || DumpType == DIDT_AppleTypes)
-    dumpAccelSection(OS, "apple_types", getAppleTypesSection(),
-                     getStringSection(), isLittleEndian());
+    dumpAccelSection(OS, "apple_types", DObj, DObj.getAppleTypesSection(),
+                     DObj.getStringSection(), isLittleEndian());
 
   if (DumpType == DIDT_All || DumpType == DIDT_AppleNamespaces)
-    dumpAccelSection(OS, "apple_namespaces", getAppleNamespacesSection(),
-                     getStringSection(), isLittleEndian());
+    dumpAccelSection(OS, "apple_namespaces", DObj,
+                     DObj.getAppleNamespacesSection(), DObj.getStringSection(),
+                     isLittleEndian());
 
   if (DumpType == DIDT_All || DumpType == DIDT_AppleObjC)
-    dumpAccelSection(OS, "apple_objc", getAppleObjCSection(),
-                     getStringSection(), isLittleEndian());
+    dumpAccelSection(OS, "apple_objc", DObj, DObj.getAppleObjCSection(),
+                     DObj.getStringSection(), isLittleEndian());
 }
 
 DWARFCompileUnit *DWARFContext::getDWOCompileUnitForHash(uint64_t Hash) {

   if (CUIndex)
     return *CUIndex;
 
-  DataExtractor CUIndexData(getCUIndexSection(), isLittleEndian(), 0);
+  DataExtractor CUIndexData(DObj.getCUIndexSection(), isLittleEndian(), 0);
 
   CUIndex = llvm::make_unique<DWARFUnitIndex>(DW_SECT_INFO);
   CUIndex->parse(CUIndexData);

   if (TUIndex)
     return *TUIndex;
 
-  DataExtractor TUIndexData(getTUIndexSection(), isLittleEndian(), 0);
+  DataExtractor TUIndexData(DObj.getTUIndexSection(), isLittleEndian(), 0);
 
   TUIndex = llvm::make_unique<DWARFUnitIndex>(DW_SECT_TYPES);
   TUIndex->parse(TUIndexData);

   if (GdbIndex)
     return *GdbIndex;
 
-  DataExtractor GdbIndexData(getGdbIndexSection(), true /*LE*/, 0);
+  DataExtractor GdbIndexData(DObj.getGdbIndexSection(), true /*LE*/, 0);
   GdbIndex = llvm::make_unique<DWARFGdbIndex>();
   GdbIndex->parse(GdbIndexData);
   return *GdbIndex;

   if (Abbrev)
     return Abbrev.get();
 
-  DataExtractor abbrData(getAbbrevSection(), isLittleEndian(), 0);
+  DataExtractor abbrData(DObj.getAbbrevSection(), isLittleEndian(), 0);
 
   Abbrev.reset(new DWARFDebugAbbrev());
   Abbrev->extract(abbrData);

   if (AbbrevDWO)
     return AbbrevDWO.get();
 
-  DataExtractor abbrData(getAbbrevDWOSection(), isLittleEndian(), 0);
+  DataExtractor abbrData(DObj.getAbbrevDWOSection(), isLittleEndian(), 0);
   AbbrevDWO.reset(new DWARFDebugAbbrev());
   AbbrevDWO->extract(abbrData);
   return AbbrevDWO.get();

   Loc.reset(new DWARFDebugLoc);
   // assume all compile units have the same address byte size
   if (getNumCompileUnits()) {
-    DWARFDataExtractor LocData(getLocSection(), isLittleEndian(),
+    DWARFDataExtractor LocData(DObj, DObj.getLocSection(), isLittleEndian(),
                                getCompileUnitAtIndex(0)->getAddressByteSize());
     Loc->parse(LocData);
   }

   if (LocDWO)
     return LocDWO.get();
 
-  DataExtractor LocData(getLocDWOSection().Data, isLittleEndian(), 0);
+  DataExtractor LocData(DObj.getLocDWOSection().Data, isLittleEndian(), 0);
   LocDWO.reset(new DWARFDebugLocDWO());
   LocDWO->parse(LocData);
   return LocDWO.get();

   // provides this information). This problem is fixed in DWARFv4
   // See this dwarf-discuss discussion for more details:
   // http://lists.dwarfstd.org/htdig.cgi/dwarf-discuss-dwarfstd.org/2011-December/001173.html
-  DataExtractor debugFrameData(getDebugFrameSection(), isLittleEndian(),
-                               getAddressSize());
+  DataExtractor debugFrameData(DObj.getDebugFrameSection(), isLittleEndian(),
+                               DObj.getAddressSize());
   DebugFrame.reset(new DWARFDebugFrame(false /* IsEH */));
   DebugFrame->parse(debugFrameData);
   return DebugFrame.get();

   if (EHFrame)
     return EHFrame.get();
 
-  DataExtractor debugFrameData(getEHFrameSection(), isLittleEndian(),
-                               getAddressSize());
+  DataExtractor debugFrameData(DObj.getEHFrameSection(), isLittleEndian(),
+                               DObj.getAddressSize());
   DebugFrame.reset(new DWARFDebugFrame(true /* IsEH */));
   DebugFrame->parse(debugFrameData);
   return DebugFrame.get();

   if (Macro)
     return Macro.get();
 
-  DataExtractor MacinfoData(getMacinfoSection(), isLittleEndian(), 0);
+  DataExtractor MacinfoData(DObj.getMacinfoSection(), isLittleEndian(), 0);
   Macro.reset(new DWARFDebugMacro());
   Macro->parse(MacinfoData);
   return Macro.get();

     return nullptr;  
 
   // We have to parse it first.
-  DWARFDataExtractor lineData(U->getLineSection(), isLittleEndian(),
+  DWARFDataExtractor lineData(DObj, U->getLineSection(), isLittleEndian(),
                               U->getAddressByteSize());
   return Line->getOrParseLineTable(lineData, stmtOffset);
 }
 
 void DWARFContext::parseCompileUnits() {
-  CUs.parse(*this, getInfoSection());
+  CUs.parse(*this, DObj.getInfoSection());
 }
 
 void DWARFContext::parseTypeUnits() {
   if (!TUs.empty())
     return;
-  forEachTypesSections([&](const DWARFSection &S) {
+  DObj.forEachTypesSections([&](const DWARFSection &S) {
     TUs.emplace_back();
     TUs.back().parse(*this, S);
   });
 }
 
 void DWARFContext::parseDWOCompileUnits() {
-  DWOCUs.parseDWO(*this, getInfoDWOSection());
+  DWOCUs.parseDWO(*this, DObj.getInfoDWOSection());
 }
 
 void DWARFContext::parseDWOTypeUnits() {
   if (!DWOTUs.empty())
     return;
-  forEachTypesDWOSections([&](const DWARFSection &S) {
+  DObj.forEachTypesDWOSections([&](const DWARFSection &S) {
     DWOTUs.emplace_back();
     DWOTUs.back().parseDWO(*this, S);
   });

   SmallString<128> DWPName;
   Expected<OwningBinary<ObjectFile>> Obj = [&] {
     if (!CheckedForDWP) {
-      (getFileName() + ".dwp").toVector(DWPName);
+      (DObj.getFileName() + ".dwp").toVector(DWPName);
       auto Obj = object::ObjectFile::createObjectFile(DWPName);
       if (Obj) {
         Entry = &DWP;

   return MachObj->isRelocationScattered(RelocInfo);
 }
 
-Error DWARFContextInMemory::maybeDecompress(const SectionRef &Sec,
-                                            StringRef Name, StringRef &Data) {
-  if (!Decompressor::isCompressed(Sec))
-    return Error::success();
+ErrorPolicy DWARFContextInMemory::defaultErrorHandler(Error E) {
+  errs() << "error: " + toString(std::move(E)) << '\n';
+  return ErrorPolicy::Continue;
+}
 
-  Expected<Decompressor> Decompressor =
-      Decompressor::create(Name, Data, IsLittleEndian, AddressSize == 8);
-  if (!Decompressor)
-    return Decompressor.takeError();
+class DWARFObjInMemory final : public DWARFObj {
+  bool IsLittleEndian;
+  uint8_t AddressSize;
+  StringRef FileName;
+
+  using TypeSectionMap = MapVector<object::SectionRef, DWARFSectionMap,
+                                   std::map<object::SectionRef, unsigned>>;
+
+  TypeSectionMap TypesSections;
+  TypeSectionMap TypesDWOSections;
+
+  DWARFSectionMap InfoSection;
+  DWARFSectionMap LocSection;
+  DWARFSectionMap LineSection;
+  DWARFSectionMap RangeSection;
+  DWARFSectionMap StringOffsetSection;
+  DWARFSectionMap InfoDWOSection;
+  DWARFSectionMap LineDWOSection;
+  DWARFSectionMap LocDWOSection;
+  DWARFSectionMap StringOffsetDWOSection;
+  DWARFSectionMap RangeDWOSection;
+  DWARFSectionMap AddrSection;
+  DWARFSectionMap AppleNamesSection;
+  DWARFSectionMap AppleTypesSection;
+  DWARFSectionMap AppleNamespacesSection;
+  DWARFSectionMap AppleObjCSection;
+
+  DWARFSectionMap *mapNameToDWARFSection(StringRef Name) {
+    return StringSwitch<DWARFSectionMap *>(Name)
+        .Case("debug_info", &InfoSection)
+        .Case("debug_loc", &LocSection)
+        .Case("debug_line", &LineSection)
+        .Case("debug_str_offsets", &StringOffsetSection)
+        .Case("debug_ranges", &RangeSection)
+        .Case("debug_info.dwo", &InfoDWOSection)
+        .Case("debug_loc.dwo", &LocDWOSection)
+        .Case("debug_line.dwo", &LineDWOSection)
+        .Case("debug_str_offsets.dwo", &StringOffsetDWOSection)
+        .Case("debug_addr", &AddrSection)
+        .Case("apple_names", &AppleNamesSection)
+        .Case("apple_types", &AppleTypesSection)
+        .Case("apple_namespaces", &AppleNamespacesSection)
+        .Case("apple_namespac", &AppleNamespacesSection)
+        .Case("apple_objc", &AppleObjCSection)
+        .Default(nullptr);
+  }
 
-  SmallString<32> Out;
-  if (auto Err = Decompressor->resizeAndDecompress(Out))
-    return Err;
+  StringRef AbbrevSection;
+  StringRef ARangeSection;
+  StringRef DebugFrameSection;
+  StringRef EHFrameSection;
+  StringRef StringSection;
+  StringRef MacinfoSection;
+  StringRef PubNamesSection;
+  StringRef PubTypesSection;
+  StringRef GnuPubNamesSection;
+  StringRef AbbrevDWOSection;
+  StringRef StringDWOSection;
+  StringRef GnuPubTypesSection;
+  StringRef CUIndexSection;
+  StringRef GdbIndexSection;
+  StringRef TUIndexSection;
+
+  SmallVector<SmallString<32>, 4> UncompressedSections;
+
+  StringRef *mapSectionToMember(StringRef Name) {
+    if (DWARFSection *Sec = mapNameToDWARFSection(Name))
+      return &Sec->Data;
+    return StringSwitch<StringRef *>(Name)
+        .Case("debug_abbrev", &AbbrevSection)
+        .Case("debug_aranges", &ARangeSection)
+        .Case("debug_frame", &DebugFrameSection)
+        .Case("eh_frame", &EHFrameSection)
+        .Case("debug_str", &StringSection)
+        .Case("debug_macinfo", &MacinfoSection)
+        .Case("debug_pubnames", &PubNamesSection)
+        .Case("debug_pubtypes", &PubTypesSection)
+        .Case("debug_gnu_pubnames", &GnuPubNamesSection)
+        .Case("debug_gnu_pubtypes", &GnuPubTypesSection)
+        .Case("debug_abbrev.dwo", &AbbrevDWOSection)
+        .Case("debug_str.dwo", &StringDWOSection)
+        .Case("debug_cu_index", &CUIndexSection)
+        .Case("debug_tu_index", &TUIndexSection)
+        .Case("gdb_index", &GdbIndexSection)
+        // Any more debug info sections go here.
+        .Default(nullptr);
+  }
 
-  UncompressedSections.emplace_back(std::move(Out));
-  Data = UncompressedSections.back();
+  /// If Sec is compressed section, decompresses and updates its contents
+  /// provided by Data. Otherwise leaves it unchanged.
+  Error maybeDecompress(const object::SectionRef &Sec, StringRef Name,
+                        StringRef &Data) {
+    if (!Decompressor::isCompressed(Sec))
+      return Error::success();
 
-  return Error::success();
-}
+    Expected<Decompressor> Decompressor =
+        Decompressor::create(Name, Data, IsLittleEndian, AddressSize == 8);
+    if (!Decompressor)
+      return Decompressor.takeError();
 
-ErrorPolicy DWARFContextInMemory::defaultErrorHandler(Error E) {
-  errs() << "error: " + toString(std::move(E)) << '\n';
-  return ErrorPolicy::Continue;
-}
+    SmallString<32> Out;
+    if (auto Err = Decompressor->resizeAndDecompress(Out))
+      return Err;
 
-DWARFContextInMemory::DWARFContextInMemory(
-    const object::ObjectFile &Obj, const LoadedObjectInfo *L,
-    function_ref<ErrorPolicy(Error)> HandleError)
-    : FileName(Obj.getFileName()), IsLittleEndian(Obj.isLittleEndian()),
-      AddressSize(Obj.getBytesInAddress()) {
-  for (const SectionRef &Section : Obj.sections()) {
-    StringRef Name;
-    Section.getName(Name);
-    // Skip BSS and Virtual sections, they aren't interesting.
-    if (Section.isBSS() || Section.isVirtual())
-      continue;
-
-    StringRef Data;
-    section_iterator RelocatedSection = Section.getRelocatedSection();
-    // Try to obtain an already relocated version of this section.
-    // Else use the unrelocated section from the object file. We'll have to
-    // apply relocations ourselves later.
-    if (!L || !L->getLoadedSectionContents(*RelocatedSection, Data))
-      Section.getContents(Data);
-
-    if (auto Err = maybeDecompress(Section, Name, Data)) {
-      ErrorPolicy EP = HandleError(
-          createError("failed to decompress '" + Name + "', ", std::move(Err)));
-      if (EP == ErrorPolicy::Halt)
-        return;
-      continue;
-    }
+    UncompressedSections.emplace_back(std::move(Out));
+    Data = UncompressedSections.back();
+
+    return Error::success();
+  }
 
-    // Compressed sections names in GNU style starts from ".z",
-    // at this point section is decompressed and we drop compression prefix.
-    Name = Name.substr(
-        Name.find_first_not_of("._z")); // Skip ".", "z" and "_" prefixes.
+public:
+  DWARFObjInMemory(const StringMap<std::unique_ptr<MemoryBuffer>> &Sections,
+                   uint8_t AddrSize, bool IsLittleEndian)
+      : IsLittleEndian(IsLittleEndian) {
+    for (const auto &SecIt : Sections) {
+      if (StringRef *SectionData = mapSectionToMember(SecIt.first()))
+        *SectionData = SecIt.second->getBuffer();
+    }
+  }
+  DWARFObjInMemory(const object::ObjectFile &Obj, const LoadedObjectInfo *L,
+                   function_ref<ErrorPolicy(Error)> HandleError)
+      : IsLittleEndian(Obj.isLittleEndian()),
+        AddressSize(Obj.getBytesInAddress()), FileName(Obj.getFileName()) {
+
+    for (const SectionRef &Section : Obj.sections()) {
+      StringRef Name;
+      Section.getName(Name);
+      // Skip BSS and Virtual sections, they aren't interesting.
+      if (Section.isBSS() || Section.isVirtual())
+        continue;
 
-    // Map platform specific debug section names to DWARF standard section
-    // names.
-    Name = Obj.mapDebugSectionName(Name);
+      StringRef Data;
+      section_iterator RelocatedSection = Section.getRelocatedSection();
+      // Try to obtain an already relocated version of this section.
+      // Else use the unrelocated section from the object file. We'll have to
+      // apply relocations ourselves later.
+      if (!L || !L->getLoadedSectionContents(*RelocatedSection, Data))
+        Section.getContents(Data);
+
+      if (auto Err = maybeDecompress(Section, Name, Data)) {
+        ErrorPolicy EP = HandleError(createError(
+            "failed to decompress '" + Name + "', ", std::move(Err)));
+        if (EP == ErrorPolicy::Halt)
+          return;
+        continue;
+      }
 
-    if (StringRef *SectionData = mapSectionToMember(Name)) {
-      *SectionData = Data;
-      if (Name == "debug_ranges") {
-        // FIXME: Use the other dwo range section when we emit it.
-        RangeDWOSection.Data = Data;
+      // Compressed sections names in GNU style starts from ".z",
+      // at this point section is decompressed and we drop compression prefix.
+      Name = Name.substr(
+          Name.find_first_not_of("._z")); // Skip ".", "z" and "_" prefixes.
+
+      // Map platform specific debug section names to DWARF standard section
+      // names.
+      Name = Obj.mapDebugSectionName(Name);
+
+      if (StringRef *SectionData = mapSectionToMember(Name)) {
+        *SectionData = Data;
+        if (Name == "debug_ranges") {
+          // FIXME: Use the other dwo range section when we emit it.
+          RangeDWOSection.Data = Data;
+        }
+      } else if (Name == "debug_types") {
+        // Find debug_types data by section rather than name as there are
+        // multiple, comdat grouped, debug_types sections.
+        TypesSections[Section].Data = Data;
+      } else if (Name == "debug_types.dwo") {
+        TypesDWOSections[Section].Data = Data;
       }
-    } else if (Name == "debug_types") {
-      // Find debug_types data by section rather than name as there are
-      // multiple, comdat grouped, debug_types sections.
-      TypesSections[Section].Data = Data;
-    } else if (Name == "debug_types.dwo") {
-      TypesDWOSections[Section].Data = Data;
-    }
 
       if (RelocatedSection == Obj.section_end())
-      continue;
-
-    StringRef RelSecName;
-    StringRef RelSecData;
-    RelocatedSection->getName(RelSecName);
-
-    // If the section we're relocating was relocated already by the JIT,
-    // then we used the relocated version above, so we do not need to process
-    // relocations for it now.
-    if (L && L->getLoadedSectionContents(*RelocatedSection, RelSecData))
-      continue;
-
-    // In Mach-o files, the relocations do not need to be applied if
-    // there is no load offset to apply. The value read at the
-    // relocation point already factors in the section address
-    // (actually applying the relocations will produce wrong results
-    // as the section address will be added twice).
-    if (!L && isa<MachOObjectFile>(&Obj))
-      continue;
-
-    RelSecName = RelSecName.substr(
-        RelSecName.find_first_not_of("._z")); // Skip . and _ prefixes.
-
-    // TODO: Add support for relocations in other sections as needed.
-    // Record relocations for the debug_info and debug_line sections.
-    DWARFSection *Sec = mapNameToDWARFSection(RelSecName);
-    RelocAddrMap *Map = Sec ? &Sec->Relocs : nullptr;
-    if (!Map) {
-      // Find debug_types relocs by section rather than name as there are
-      // multiple, comdat grouped, debug_types sections.
-      if (RelSecName == "debug_types")
-        Map = &TypesSections[*RelocatedSection].Relocs;
-      else if (RelSecName == "debug_types.dwo")
-        Map = &TypesDWOSections[*RelocatedSection].Relocs;
-      else
         continue;
-    }
 
-    if (Section.relocation_begin() == Section.relocation_end())
-      continue;
+      StringRef RelSecName;
+      StringRef RelSecData;
+      RelocatedSection->getName(RelSecName);
 
-    // Symbol to [address, section index] cache mapping.
-    std::map<SymbolRef, SymInfo> AddrCache;
-    for (const RelocationRef &Reloc : Section.relocations()) {
-      // FIXME: it's not clear how to correctly handle scattered
-      // relocations.
-      if (isRelocScattered(Obj, Reloc))
+      // If the section we're relocating was relocated already by the JIT,
+      // then we used the relocated version above, so we do not need to process
+      // relocations for it now.
+      if (L && L->getLoadedSectionContents(*RelocatedSection, RelSecData))
         continue;
 
-      Expected<SymInfo> SymInfoOrErr = getSymbolInfo(Obj, Reloc, L, AddrCache);
-      if (!SymInfoOrErr) {
-        if (HandleError(SymInfoOrErr.takeError()) == ErrorPolicy::Halt)
-          return;
+      // In Mach-o files, the relocations do not need to be applied if
+      // there is no load offset to apply. The value read at the
+      // relocation point already factors in the section address
+      // (actually applying the relocations will produce wrong results
+      // as the section address will be added twice).
+      if (!L && isa<MachOObjectFile>(&Obj))
         continue;
+
+      RelSecName = RelSecName.substr(
+          RelSecName.find_first_not_of("._z")); // Skip . and _ prefixes.
+
+      // TODO: Add support for relocations in other sections as needed.
+      // Record relocations for the debug_info and debug_line sections.
+      DWARFSectionMap *Sec = mapNameToDWARFSection(RelSecName);
+      RelocAddrMap *Map = Sec ? &Sec->Relocs : nullptr;
+      if (!Map) {
+        // Find debug_types relocs by section rather than name as there are
+        // multiple, comdat grouped, debug_types sections.
+        if (RelSecName == "debug_types")
+          Map =
+              &static_cast<DWARFSectionMap &>(TypesSections[*RelocatedSection])
+                   .Relocs;
+        else if (RelSecName == "debug_types.dwo")
+          Map = &static_cast<DWARFSectionMap &>(
+                     TypesDWOSections[*RelocatedSection])
+                     .Relocs;
+        else
+          continue;
       }
 
-      object::RelocVisitor V(Obj);
-      uint64_t Val = V.visit(Reloc.getType(), Reloc, SymInfoOrErr->Address);
-      if (V.error()) {
-        SmallString<32> Type;
-        Reloc.getTypeName(Type);
-        ErrorPolicy EP = HandleError(
-            createError("failed to compute relocation: " + Type + ", ",
-                        errorCodeToError(object_error::parse_failed)));
-        if (EP == ErrorPolicy::Halt)
-          return;
+      if (Section.relocation_begin() == Section.relocation_end())
         continue;
+
+      // Symbol to [address, section index] cache mapping.
+      std::map<SymbolRef, SymInfo> AddrCache;
+      for (const RelocationRef &Reloc : Section.relocations()) {
+        // FIXME: it's not clear how to correctly handle scattered
+        // relocations.
+        if (isRelocScattered(Obj, Reloc))
+          continue;
+
+        Expected<SymInfo> SymInfoOrErr =
+            getSymbolInfo(Obj, Reloc, L, AddrCache);
+        if (!SymInfoOrErr) {
+          if (HandleError(SymInfoOrErr.takeError()) == ErrorPolicy::Halt)
+            return;
+          continue;
+        }
+
+        object::RelocVisitor V(Obj);
+        uint64_t Val = V.visit(Reloc.getType(), Reloc, SymInfoOrErr->Address);
+        if (V.error()) {
+          SmallString<32> Type;
+          Reloc.getTypeName(Type);
+          ErrorPolicy EP = HandleError(
+              createError("failed to compute relocation: " + Type + ", ",
+                          errorCodeToError(object_error::parse_failed)));
+          if (EP == ErrorPolicy::Halt)
+            return;
+          continue;
+        }
+        RelocAddrEntry Rel = {SymInfoOrErr->SectionIndex, Val};
+        Map->insert({Reloc.getOffset(), Rel});
       }
-      RelocAddrEntry Rel = {SymInfoOrErr->SectionIndex, Val};
-      Map->insert({Reloc.getOffset(), Rel});
     }
   }
-}
 
-DWARFContextInMemory::DWARFContextInMemory(
-    const StringMap<std::unique_ptr<MemoryBuffer>> &Sections, uint8_t AddrSize,
-    bool isLittleEndian)
-    : IsLittleEndian(isLittleEndian), AddressSize(AddrSize) {
-  for (const auto &SecIt : Sections) {
-    if (StringRef *SectionData = mapSectionToMember(SecIt.first()))
-      *SectionData = SecIt.second->getBuffer();
+  Optional<RelocAddrEntry> find(const DWARFSection &S,
+                                uint64_t Pos) const override {
+    auto &Sec = static_cast<const DWARFSectionMap &>(S);
+    RelocAddrMap::const_iterator AI = Sec.Relocs.find(Pos);
+    if (AI == Sec.Relocs.end())
+      return None;
+    return AI->second;
   }
-}
 
-DWARFSection *DWARFContextInMemory::mapNameToDWARFSection(StringRef Name) {
-  return StringSwitch<DWARFSection *>(Name)
-      .Case("debug_info", &InfoSection)
-      .Case("debug_loc", &LocSection)
-      .Case("debug_line", &LineSection)
-      .Case("debug_str_offsets", &StringOffsetSection)
-      .Case("debug_ranges", &RangeSection)
-      .Case("debug_info.dwo", &InfoDWOSection)
-      .Case("debug_loc.dwo", &LocDWOSection)
-      .Case("debug_line.dwo", &LineDWOSection)
-      .Case("debug_str_offsets.dwo", &StringOffsetDWOSection)
-      .Case("debug_addr", &AddrSection)
-      .Case("apple_names", &AppleNamesSection)
-      .Case("apple_types", &AppleTypesSection)
-      .Case("apple_namespaces", &AppleNamespacesSection)
-      .Case("apple_namespac", &AppleNamespacesSection)
-      .Case("apple_objc", &AppleObjCSection)
-      .Default(nullptr);
-}
+  bool isLittleEndian() const override { return IsLittleEndian; }
+  StringRef getAbbrevDWOSection() const override { return AbbrevDWOSection; }
+  const DWARFSection &getLineDWOSection() const override {
+    return LineDWOSection;
+  }
+  const DWARFSection &getLocDWOSection() const override {
+    return LocDWOSection;
+  }
+  StringRef getStringDWOSection() const override { return StringDWOSection; }
+  const DWARFSection &getStringOffsetDWOSection() const override {
+    return StringOffsetDWOSection;
+  }
+  const DWARFSection &getRangeDWOSection() const override {
+    return RangeDWOSection;
+  }
+  const DWARFSection &getAddrSection() const override { return AddrSection; }
+  StringRef getCUIndexSection() const override { return CUIndexSection; }
+  StringRef getGdbIndexSection() const override { return GdbIndexSection; }
+  StringRef getTUIndexSection() const override { return TUIndexSection; }
+
+  // DWARF v5
+  const DWARFSection &getStringOffsetSection() const override {
+    return StringOffsetSection;
+  }
 
-StringRef *DWARFContextInMemory::mapSectionToMember(StringRef Name) {
-  if (DWARFSection *Sec = mapNameToDWARFSection(Name))
-    return &Sec->Data;
-  return StringSwitch<StringRef *>(Name)
-      .Case("debug_abbrev", &AbbrevSection)
-      .Case("debug_aranges", &ARangeSection)
-      .Case("debug_frame", &DebugFrameSection)
-      .Case("eh_frame", &EHFrameSection)
-      .Case("debug_str", &StringSection)
-      .Case("debug_macinfo", &MacinfoSection)
-      .Case("debug_pubnames", &PubNamesSection)
-      .Case("debug_pubtypes", &PubTypesSection)
-      .Case("debug_gnu_pubnames", &GnuPubNamesSection)
-      .Case("debug_gnu_pubtypes", &GnuPubTypesSection)
-      .Case("debug_abbrev.dwo", &AbbrevDWOSection)
-      .Case("debug_str.dwo", &StringDWOSection)
-      .Case("debug_cu_index", &CUIndexSection)
-      .Case("debug_tu_index", &TUIndexSection)
-      .Case("gdb_index", &GdbIndexSection)
-      // Any more debug info sections go here.
-      .Default(nullptr);
+  // Sections for DWARF5 split dwarf proposal.
+  const DWARFSection &getInfoDWOSection() const override {
+    return InfoDWOSection;
+  }
+  void forEachTypesDWOSections(
+      function_ref<void(const DWARFSection &)> F) const override {
+    for (auto &P : TypesDWOSections)
+      F(P.second);
+  }
+
+  StringRef getAbbrevSection() const override { return AbbrevSection; }
+  const DWARFSection &getLocSection() const override { return LocSection; }
+  StringRef getARangeSection() const override { return ARangeSection; }
+  StringRef getDebugFrameSection() const override { return DebugFrameSection; }
+  StringRef getEHFrameSection() const override { return EHFrameSection; }
+  const DWARFSection &getLineSection() const override { return LineSection; }
+  StringRef getStringSection() const override { return StringSection; }
+  const DWARFSection &getRangeSection() const override { return RangeSection; }
+  StringRef getMacinfoSection() const override { return MacinfoSection; }
+  StringRef getPubNamesSection() const override { return PubNamesSection; }
+  StringRef getPubTypesSection() const override { return PubTypesSection; }
+  StringRef getGnuPubNamesSection() const override {
+    return GnuPubNamesSection;
+  }
+  StringRef getGnuPubTypesSection() const override {
+    return GnuPubTypesSection;
+  }
+  const DWARFSection &getAppleNamesSection() const override {
+    return AppleNamesSection;
+  }
+  const DWARFSection &getAppleTypesSection() const override {
+    return AppleTypesSection;
+  }
+  const DWARFSection &getAppleNamespacesSection() const override {
+    return AppleNamespacesSection;
+  }
+  const DWARFSection &getAppleObjCSection() const override {
+    return AppleObjCSection;
+  }
+
+  StringRef getFileName() const override { return FileName; }
+  uint8_t getAddressSize() const override { return AddressSize; }
+  const DWARFSection &getInfoSection() const override { return InfoSection; }
+  void forEachTypesSections(
+      function_ref<void(const DWARFSection &)> F) const override {
+    for (auto &P : TypesSections)
+      F(P.second);
+  }
+};
+
+DWARFContextInMemory::DWARFContextInMemory(
+    const object::ObjectFile &Obj, const LoadedObjectInfo *L,
+    function_ref<ErrorPolicy(Error)> HandleError)
+    : DWARFContext(*new DWARFObjInMemory(Obj, L, HandleError)) {
+  DObjP.reset(&this->DObj);
 }
 
-void DWARFContextInMemory::anchor() {}
+DWARFContextInMemory::DWARFContextInMemory(
+    const StringMap<std::unique_ptr<MemoryBuffer>> &Sections, uint8_t AddrSize,
+    bool IsLittleEndian)
+    : DWARFContext(*new DWARFObjInMemory(Sections, AddrSize, IsLittleEndian)) {
+  DObjP.reset(&this->DObj);
+}

lib/DebugInfo/DWARF/DWARFDataExtractor.cpp

 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
 
 using namespace llvm;
 
 uint64_t DWARFDataExtractor::getRelocatedValue(uint32_t Size, uint32_t *Off,
                                                uint64_t *SecNdx) const {
-  if (!RelocMap)
+  if (!Section)
     return getUnsigned(Off, Size);
-  RelocAddrMap::const_iterator AI = RelocMap->find(*Off);
-  if (AI == RelocMap->end())
+  Optional<RelocAddrEntry> Rel = Obj->find(*Section, *Off);
+  if (!Rel)
     return getUnsigned(Off, Size);
   if (SecNdx)
-    *SecNdx = AI->second.SectionIndex;
-  return getUnsigned(Off, Size) + AI->second.Value;
+    *SecNdx = Rel->SectionIndex;
+  return getUnsigned(Off, Size) + Rel->Value;
 }

lib/DebugInfo/DWARF/DWARFDebugAranges.cpp

     return;
 
   // Extract aranges from .debug_aranges section.
-  DataExtractor ArangesData(CTX->getARangeSection(), CTX->isLittleEndian(), 0);
+  DataExtractor ArangesData(CTX->getDWARFObj().getARangeSection(),
+                            CTX->isLittleEndian(), 0);
   extract(ArangesData);
 
   // Generate aranges from DIEs: even if .debug_aranges section is present,

lib/DebugInfo/DWARF/DWARFUnit.cpp

 using namespace dwarf;
 
 void DWARFUnitSectionBase::parse(DWARFContext &C, const DWARFSection &Section) {
-  parseImpl(C, Section, C.getDebugAbbrev(), &C.getRangeSection(),
-            C.getStringSection(), C.getStringOffsetSection(),
-            &C.getAddrSection(), C.getLineSection(), C.isLittleEndian(), false);
+  const DWARFObj &D = C.getDWARFObj();
+  parseImpl(C, Section, C.getDebugAbbrev(), &D.getRangeSection(),
+            D.getStringSection(), D.getStringOffsetSection(),
+            &D.getAddrSection(), D.getLineSection(), D.isLittleEndian(), false);
 }
 
 void DWARFUnitSectionBase::parseDWO(DWARFContext &C,
                                     const DWARFSection &DWOSection,
                                     DWARFUnitIndex *Index) {
-  parseImpl(C, DWOSection, C.getDebugAbbrevDWO(), &C.getRangeDWOSection(),
-            C.getStringDWOSection(), C.getStringOffsetDWOSection(),
-            &C.getAddrSection(), C.getLineDWOSection(), C.isLittleEndian(),
+  const DWARFObj &D = C.getDWARFObj();
+  parseImpl(C, DWOSection, C.getDebugAbbrevDWO(), &D.getRangeDWOSection(),
+            D.getStringDWOSection(), D.getStringOffsetDWOSection(),
+            &D.getAddrSection(), D.getLineDWOSection(), C.isLittleEndian(),
             true);
 }
 

 
 DWARFUnit::~DWARFUnit() = default;
 
+DWARFDataExtractor DWARFUnit::getDebugInfoExtractor() const {
+  return DWARFDataExtractor(Context.getDWARFObj(), InfoSection, isLittleEndian,
+                            getAddressByteSize());
+}
+
 bool DWARFUnit::getAddrOffsetSectionItem(uint32_t Index,
                                                 uint64_t &Result) const {
   uint32_t Offset = AddrOffsetSectionBase + Index * getAddressByteSize();
   if (AddrOffsetSection->Data.size() < Offset + getAddressByteSize())
     return false;
-  DWARFDataExtractor DA(*AddrOffsetSection, isLittleEndian,
-                        getAddressByteSize());
+  DWARFDataExtractor DA(Context.getDWARFObj(), *AddrOffsetSection,
+                        isLittleEndian, getAddressByteSize());
   Result = DA.getRelocatedAddress(&Offset);
   return true;
 }

   uint32_t Offset = StringOffsetSectionBase + Index * ItemSize;
   if (StringOffsetSection.Data.size() < Offset + ItemSize)
     return false;
-  DWARFDataExtractor DA(StringOffsetSection, isLittleEndian, 0);
+  DWARFDataExtractor DA(Context.getDWARFObj(), StringOffsetSection,
+                        isLittleEndian, 0);
   Result = DA.getRelocatedValue(ItemSize, &Offset);
   return true;
 }

                                  DWARFDebugRangeList &RangeList) const {
   // Require that compile unit is extracted.
   assert(!DieArray.empty());
-  DWARFDataExtractor RangesData(*RangeSection, isLittleEndian,
-                                getAddressByteSize());
+  DWARFDataExtractor RangesData(Context.getDWARFObj(), *RangeSection,
+                                isLittleEndian, getAddressByteSize());
   uint32_t ActualRangeListOffset = RangeSectionBase + RangeListOffset;
   return RangeList.extract(RangesData, &ActualRangeListOffset);
 }

lib/DebugInfo/DWARF/DWARFVerifier.cpp

   case DW_AT_ranges:
     // Make sure the offset in the DW_AT_ranges attribute is valid.
     if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
-      if (*SectionOffset >= DCtx.getRangeSection().Data.size()) {
+      if (*SectionOffset >= DCtx.getDWARFObj().getRangeSection().Data.size()) {
         ++NumDebugInfoErrors;
         OS << "error: DW_AT_ranges offset is beyond .debug_ranges "
               "bounds:\n";

   case DW_AT_stmt_list:
     // Make sure the offset in the DW_AT_stmt_list attribute is valid.
     if (auto SectionOffset = AttrValue.Value.getAsSectionOffset()) {
-      if (*SectionOffset >= DCtx.getLineSection().Data.size()) {
+      if (*SectionOffset >= DCtx.getDWARFObj().getLineSection().Data.size()) {
         ++NumDebugInfoErrors;
         OS << "error: DW_AT_stmt_list offset is beyond .debug_line "
               "bounds: "

 
 void DWARFVerifier::verifyDebugInfoForm(const DWARFDie &Die,
                                         DWARFAttribute &AttrValue) {
+  const DWARFObj &D = DCtx.getDWARFObj();
   const auto Form = AttrValue.Value.getForm();
   switch (Form) {
   case DW_FORM_ref1:

     Optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
     assert(RefVal);
     if (RefVal) {
-      if (*RefVal >= DCtx.getInfoSection().Data.size()) {
+      if (*RefVal >= D.getInfoSection().Data.size()) {
         ++NumDebugInfoErrors;
         OS << "error: DW_FORM_ref_addr offset beyond .debug_info "
               "bounds:\n";

   case DW_FORM_strp: {
     auto SecOffset = AttrValue.Value.getAsSectionOffset();
     assert(SecOffset); // DW_FORM_strp is a section offset.
-    if (SecOffset && *SecOffset >= DCtx.getStringSection().size()) {
+    if (SecOffset && *SecOffset >= D.getStringSection().size()) {
       ++NumDebugInfoErrors;
       OS << "error: DW_FORM_strp offset beyond .debug_str bounds:\n";
       Die.dump(OS, 0);

       continue;
     const uint32_t LineTableOffset = *StmtSectionOffset;
     auto LineTable = DCtx.getLineTableForUnit(CU.get());
-    if (LineTableOffset < DCtx.getLineSection().Data.size()) {
+    if (LineTableOffset < DCtx.getDWARFObj().getLineSection().Data.size()) {
       if (!LineTable) {
         ++NumDebugLineErrors;
         OS << "error: .debug_line[" << format("0x%08" PRIx32, LineTableOffset)

 
 bool DWARFVerifier::handleAppleNames() {
   NumAppleNamesErrors = 0;
-
-  DWARFDataExtractor AppleNamesSection(DCtx.getAppleNamesSection(),
+  const DWARFObj &D = DCtx.getDWARFObj();
+  DWARFDataExtractor AppleNamesSection(D, D.getAppleNamesSection(),
                                        DCtx.isLittleEndian(), 0);
-  DataExtractor StrData(DCtx.getStringSection(), DCtx.isLittleEndian(), 0);
+  DataExtractor StrData(D.getStringSection(), DCtx.isLittleEndian(), 0);
   DWARFAcceleratorTable AppleNames(AppleNamesSection, StrData);
 
   if (!AppleNames.extract()) {

tools/dsymutil/DwarfLinker.cpp

   MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLocSection());
 
   unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
-  const DWARFSection &InputSec = Dwarf.getLocSection();
+  const DWARFSection &InputSec = Dwarf.getDWARFObj().getLocSection();
   DataExtractor Data(InputSec.Data, Dwarf.isLittleEndian(), AddressSize);
   DWARFUnit &OrigUnit = Unit.getOrigUnit();
   auto OrigUnitDie = OrigUnit.getUnitDIE(false);

   DWARFDebugRangeList RangeList;
   const auto &FunctionRanges = Unit.getFunctionRanges();
   unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
-  DWARFDataExtractor RangeExtractor(OrigDwarf.getRangeSection(),
+  DWARFDataExtractor RangeExtractor(OrigDwarf.getDWARFObj(),
+                                    OrigDwarf.getDWARFObj().getRangeSection(),
                                     OrigDwarf.isLittleEndian(), AddressSize);
   auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
   DWARFUnit &OrigUnit = Unit.getOrigUnit();

   // Parse the original line info for the unit.
   DWARFDebugLine::LineTable LineTable;
   uint32_t StmtOffset = *StmtList;
-  DWARFDataExtractor LineExtractor(OrigDwarf.getLineSection(),
-                                   OrigDwarf.isLittleEndian(),
-                                   Unit.getOrigUnit().getAddressByteSize());
+  DWARFDataExtractor LineExtractor(
+      OrigDwarf.getDWARFObj(), OrigDwarf.getDWARFObj().getLineSection(),
+      OrigDwarf.isLittleEndian(), Unit.getOrigUnit().getAddressByteSize());
   LineTable.parse(LineExtractor, &StmtOffset);
 
   // This vector is the output line table.

       LineTable.Prologue.OpcodeBase > 13)
     reportWarning("line table parameters mismatch. Cannot emit.");
   else {
-    StringRef LineData = OrigDwarf.getLineSection().Data;
+    StringRef LineData = OrigDwarf.getDWARFObj().getLineSection().Data;
     MCDwarfLineTableParams Params;
     Params.DWARF2LineOpcodeBase = LineTable.Prologue.OpcodeBase;
     Params.DWARF2LineBase = LineTable.Prologue.LineBase;

 void DwarfLinker::patchFrameInfoForObject(const DebugMapObject &DMO,
                                           DWARFContext &OrigDwarf,
                                           unsigned AddrSize) {
-  StringRef FrameData = OrigDwarf.getDebugFrameSection();
+  StringRef FrameData = OrigDwarf.getDWARFObj().getDebugFrameSection();
   if (FrameData.empty())
     return;
 

tools/obj2yaml/dwarf2yaml.cpp

 }
 
 void dumpDebugStrings(DWARFContextInMemory &DCtx, DWARFYAML::Data &Y) {
-  StringRef RemainingTable = DCtx.getStringSection();
+  StringRef RemainingTable = DCtx.getDWARFObj().getStringSection();
   while (RemainingTable.size() > 0) {
     auto SymbolPair = RemainingTable.split('\0');
     RemainingTable = SymbolPair.second;

 }
 
 void dumpDebugARanges(DWARFContextInMemory &DCtx, DWARFYAML::Data &Y) {
-  DataExtractor ArangesData(DCtx.getARangeSection(), DCtx.isLittleEndian(), 0);
+  DataExtractor ArangesData(DCtx.getDWARFObj().getARangeSection(),
+                            DCtx.isLittleEndian(), 0);
   uint32_t Offset = 0;
   DWARFDebugArangeSet Set;
 

 }
 
 void dumpDebugPubSections(DWARFContextInMemory &DCtx, DWARFYAML::Data &Y) {
+  const DWARFObj &D = DCtx.getDWARFObj();
   Y.PubNames.IsGNUStyle = false;
-  dumpPubSection(DCtx, Y.PubNames, DCtx.getPubNamesSection());
+  dumpPubSection(DCtx, Y.PubNames, D.getPubNamesSection());
 
   Y.PubTypes.IsGNUStyle = false;
-  dumpPubSection(DCtx, Y.PubTypes, DCtx.getPubTypesSection());
+  dumpPubSection(DCtx, Y.PubTypes, D.getPubTypesSection());
 
   Y.GNUPubNames.IsGNUStyle = true;
-  dumpPubSection(DCtx, Y.GNUPubNames, DCtx.getGnuPubNamesSection());
+  dumpPubSection(DCtx, Y.GNUPubNames, D.getGnuPubNamesSection());
 
   Y.GNUPubTypes.IsGNUStyle = true;
-  dumpPubSection(DCtx, Y.GNUPubTypes, DCtx.getGnuPubTypesSection());
+  dumpPubSection(DCtx, Y.GNUPubTypes, D.getGnuPubTypesSection());
 }
 
 void dumpDebugInfo(DWARFContextInMemory &DCtx, DWARFYAML::Data &Y) {

     if (auto StmtOffset =
             dwarf::toSectionOffset(CUDIE.find(dwarf::DW_AT_stmt_list))) {
       DWARFYAML::LineTable DebugLines;
-      DataExtractor LineData(DCtx.getLineSection().Data, DCtx.isLittleEndian(),
-                             CU->getAddressByteSize());
+      DataExtractor LineData(DCtx.getDWARFObj().getLineSection().Data,
+                             DCtx.isLittleEndian(), CU->getAddressByteSize());
       uint32_t Offset = *StmtOffset;
       dumpInitialLength(LineData, Offset, DebugLines.Length);
       uint64_t LineTableLength = DebugLines.Length.getLength();