[NFC] Refactor Apple Accelerator Tables

[JDevlieghere]

Summary

[NFC] Refactor Apple Accelerator Tables

This patch completely overhauls the accelerator table and makes them
truly generic. There have been several attempts to do this in the past:

• D8215 & D8216: Using a union and partial hardcoding.
• D11805: Using inheritance.
• D42246: Using a callback.

In the end I didn't like either of them, because for some reason or
another parts of it felt hacky or decreased runtime performance. I
didn't want to completely rewrite them as I was hoping that we could
reuse parts for the successor in the DWARF standard. However, it seems
less and less likely that there will be a lot of opportunities for
sharing code and/or an interface. I just went for what I think is the
proper solution to our problem.

A quick summary for why these changes are necessary: dsymutil likes to
reuse the current implementation of the Apple accelerator tables.
However, LLDB expects a slightly different interface than what is
currently emitted. Additionally, in dsymutil we only have offsets and no
actual DIEs.

Although a lot of code seems to have changed, in the end this change is
pretty straightforward:

• We turned HashDataContents into a template parameter.
• We created two implementations of this class, one for type tables and one for everything else. There will be a third one for dsymutil with just an offset.
• We use the supplied class to deduct the atoms for the header which makes the structure of the table fully self contained.
• We renamed the prefix from DWARF- to Apple- to make space for the future implementation of .debug_names.

One could argue that the latter should've been a separate patch, but
since this refactoring touches almost every line, it doesn't really
matter.

The disadvantage of this is of course that a lot of the code is moved to
the header. One mitigation was splitting off the header class so we could
have the ::Emit() method implemented in the cpp file. With regards to
includes we only need to import two more headers than before
(CodeGen/AsmPrinter.h and llvm/MC/MCStreamer.h) which seems
reasonable.

[aprantl]

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

195

Reading just the struct definition I'm a little puzzled why this needs to be a template if we are only storing a pointer to DataT. i wonder if we could get away with just templateizing one or two methods instead of the entire class.

410

Could you convert this to LLVM style with capitalized variable names?

448

does this look better as a range-based-for?

[JDevlieghere]

Thanks a lot for the prompt review Adrian!

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

195

I don't think there's anything preventing this, I just liked this approach better because:

1. No overhead of virtual calls.
2. No risk of accidentally mixing different types of data in one table. (make interfaces easy to use correctly and hard to use incorrectly)
3. No need to explicitly specify the atoms in the constructor and having it abstracted and self contained in the templated class. (same reason as 2)

Because of (2) and (3) it makes sense to have an emit interface where you call the appropriate methods to emit the data, because the atoms are right there and you have a guarantee about their form. If this is not the case, I think we should go for an interface similar to D42246 where DataT has an interface to get the data for a given atom and emit the correct form based on the atom's form; which means a loop and more function calls.

tl;dr it's an interface design decision and not a technical limitation.

410

Sure! I left it like this based on Chandler's comment here: https://reviews.llvm.org/D40987?id=126062#inline-357702

448

Definitely. I removed most of them but this one slipped through the cracks. Thanks!

[aprantl]

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

195

I'm mostly worried about code size. My understanding (please let me know if this is misinformed) is that by having the entire class be a template we will get N copies of all methods including the ones that don't depend on the templated type such as the constructor.

No overhead of virtual calls.

Do you mean virtual calls when calling methods on the Values stored in the vector?
You could templateize the emit method itself and/or create a non-template AppleAccelTableBase class that contains all the generic code and templated AppleAccelTable<DataT> inheriting from that class. That's a common pattern I've seen used all over LLVM.

[JDevlieghere]

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

195

Indeed, the virtual call would be the ::emit() method in DataT, so one indirect call for every entry in the list. Inheriting from a common base class isn't really feasible either, as every function (indirectly) depends on DataT.

As we discussed offline, I share your code size concerns. There should be at most 3 different instantiations of the template, so the growth is limited as long as no new configuration of tables are added, which is a realistic assumption given the existence of DWARFv5 accelerator tables. This also means that as we move to the DWARFv5 implementation on darwin, this will becomes less of a hot path and it might be worth settling for a little runtime overhead to save on code size.

I encourage everyone to share which of the two trade-offs they feel we should pursue.

[aprantl]

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

195

That is good point. Since this destined to become legacy code path that we will need to carry around for an indefinite time (because of backwards deployment), optimizing for code size sounds like the right approach to me. Does the implementation on opensource.apple.com also use virtual function calls or would this be a regression?

[JDevlieghere]

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

195

Alright, I will update the patch to optimize for code size. Indeed, our internal implementation already uses a the virtual call, so this would not be a regression.

[JDevlieghere]

Optimize for code size and use virtual call to ::emit().

[JDevlieghere]

Fix discrepancies with the LLVM coding standards.

[labath]

I've uploaded D42420 so you can see my current work on the debug_names generation. It's still quite ugly and there are several interactions that I still have to figure out (e.g., how do I get the list of CUs I am indexing), but the thing I want to show is that there are more opportunities for code sharing here than on the parsing side: obviously the header is completely different, but the code for emission of some individual subtables can be shared as long as we can customize the top-level emit() function to control the order. Also, the functions for gathering and processing the data (AddName, finalize) can largely be shared.

The one idea I think could make things cleaner, but I haven't tried out yet, is to split this code into two parts:

• one would deal purely with abstract data representation: gathering names, computing hashes, bucket counts, etc. This one would identical for both tables.
• the other part would deal with serialization of the abstract representation. Here we would have two classes for the two table kinds plus a base class for common functionality.

I don't think any of that affects this patch directly, but it may be interesting for you to see where the common functionality is.

[JDevlieghere]

In D42334#985062, @labath wrote:

I've uploaded D42420 so you can see my current work on the debug_names generation. It's still quite ugly and there are several interactions that I still have to figure out (e.g., how do I get the list of CUs I am indexing), but the thing I want to show is that there are more opportunities for code sharing here than on the parsing side: obviously the header is completely different, but the code for emission of some individual subtables can be shared as long as we can customize the top-level emit() function to control the order. Also, the functions for gathering and processing the data (AddName, finalize) can largely be shared.

Great, this is definitely very interesting. I'm pleasantly surprised by what you managed to push down into the AccelTable base class.

The one idea I think could make things cleaner, but I haven't tried out yet, is to split this code into two parts:

• one would deal purely with abstract data representation: gathering names, computing hashes, bucket counts, etc. This one would identical for both tables.
• the other part would deal with serialization of the abstract representation. Here we would have two classes for the two table kinds plus a base class for common functionality.

That sounds great, you have my full support on that. Let me know if/how I can help. Do you have anything particular in mind to achieve this?

I don't think any of that affects this patch directly, but it may be interesting for you to see where the common functionality is.

Definitely. This is part of the reason I want to get this change upstream now. The current implementation doesn't support all of Apple's use cases and making a change like this *after* having factored out the common parts will only make things harder. Especially because we want to support the same use cases with the DWARFv5 tables as well.

[aprantl]

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

69

Can you be specific as to which variant of accel table this is referring to?

100–102

... Conceptually it is a column with ...

325

This is just me being curious: Would it make sense to have users pass the new (Allocator) DataT(D) and not make this a template at all?

[JDevlieghere]

• Feedback Adrian

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

325

Wouldn't you agree that exposing the allocator to the caller makes a horrible interface?

[aprantl]

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

325

Fair point.

[aprantl]

I'm happy with this now, please be sure to address any outstanding feedback from Pavel, though, if any.

[JDevlieghere]

Alright!

@labath Do you have any comments/concerns/feedback?

[labath]

I find the fact that you have to specify type of data in the addName call a bit weird. This means you cannot guarantee the homogeneity of the table, as different addName calls on the same table may use different types (and none of them needs to match the atom array you passed to the constructor). It sounds to me like the data type should really a part of the table type (but you have not done that because of the code size concerns et al.).

This "non-template base class" idea has already been proposed earlier in the thread by Adrian, but got dismissed because at that point you were still trying to optimize everything for speed. Now that you already have a base class for the data types, it should be fairly trivial to implement: put everything except the constructor and the addName function in the base class; the templated constructor can implicitly take the atom array as T::Atoms, and addName will automatically construct entries of type T. That should guarantee consistency with only a tiny code size increase.

What do you think?

[JDevlieghere]

In D42334#986126, @labath wrote:

I find the fact that you have to specify type of data in the addName call a bit weird. This means you cannot guarantee the homogeneity of the table, as different addName calls on the same table may use different types (and none of them needs to match the atom array you passed to the constructor). It sounds to me like the data type should really a part of the table type (but you have not done that because of the code size concerns et al.).

Exactly.

This "non-template base class" idea has already been proposed earlier in the thread by Adrian, but got dismissed because at that point you were still trying to optimize everything for speed.

Correct, because by templating the data type we don't need a virtual call.

Now that you already have a base class for the data types, it should be fairly trivial to implement: put everything except the constructor and the addName function in the base class; the templated constructor can implicitly take the atom array as T::Atoms, and addName will automatically construct entries of type T. That should guarantee consistency with only a tiny code size increase.

What do you think?

I think it's a great idea! This would allow us to regain the strong interface I was aiming for.

[JDevlieghere]

• Split base class from templated implementation.

[labath]

Cool, thanks.

[JDevlieghere]

Thanks Pavel!

I'll wait on D42501 to land this, as I need both to merge these changes internally.

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

 // as an index into the hashes table and look at each successive hash as long
 // as the hash value is still the same modulo result (bucket value) as earlier.
 // If we have a match we look at that same entry in the offsets table and
 // grab the offset in the data for our final match.
 
 namespace llvm {
 
 class AsmPrinter;
-class DwarfDebug;
 
-class DwarfAccelTable {
-  // Helper function to compute the number of buckets needed based on
-  // the number of unique hashes.
-  void ComputeBucketCount();
-
-  struct TableHeader {
-    uint32_t magic = MagicHash; // 'HASH' magic value to allow endian detection
-    uint16_t version = 1;       // Version number.
-    uint16_t hash_function = dwarf::DW_hash_function_djb;
-    // The hash function enumeration that was used.
-    uint32_t bucket_count = 0;  // The number of buckets in this hash table.
-    uint32_t hashes_count = 0;  // The total number of unique hash values
-                                // and hash data offsets in this table.
-    uint32_t header_data_len;   // The bytes to skip to get to the hash
-                                // indexes (buckets) for correct alignment.
-    // Also written to disk is the implementation specific header data.
+/// Representation of the header of an Apple accelerator table. This consists
+/// of the fixed header and the header data. The latter contains the atoms
+/// which define the columns of the table.
+class AppleAccelTableHeader {
+  struct Header {
+    uint32_t Magic = MagicHash;
+    uint16_t Version = 1;
+    uint16_t HashFunction = dwarf::DW_hash_function_djb;
+    uint32_t BucketCount = 0;
+    uint32_t HashCount = 0;
+    uint32_t HeaderDataLength;
 
+    /// 'HASH' magic value to detect endianness.
     static const uint32_t MagicHash = 0x48415348;
 
-    TableHeader(uint32_t data_len) : header_data_len(data_len) {}
+    Header(uint32_t DataLength) : HeaderDataLength(DataLength) {}
 
 #ifndef NDEBUG
-    void print(raw_ostream &OS) {
-      OS << "Magic: " << format("0x%x", magic) << "\n"
-         << "Version: " << version << "\n"
-         << "Hash Function: " << hash_function << "\n"
-         << "Bucket Count: " << bucket_count << "\n"
-         << "Header Data Length: " << header_data_len << "\n";
+    void print(raw_ostream &OS) const {
+      OS << "Magic: " << format("0x%x", Magic) << "\n"
+         << "Version: " << Version << "\n"
+         << "Hash Function: " << HashFunction << "\n"
+         << "Bucket Count: " << BucketCount << "\n"
+         << "Header Data Length: " << HeaderDataLength << "\n";
     }
 
-    void dump() { print(dbgs()); }
+    void dump() const { print(dbgs()); }
 #endif
   };
 
 public:
-  // The HeaderData describes the form of each set of data. In general this
-  // is as a list of atoms (atom_count) where each atom contains a type
-  // (AtomType type) of data, and an encoding form (form). In the case of
-  // data that is referenced via DW_FORM_ref_* the die_offset_base is
-  // used to describe the offset for all forms in the list of atoms.
-  // This also serves as a public interface of sorts.
-  // When written to disk this will have the form:
-  //
-  // uint32_t die_offset_base
-  // uint32_t atom_count
-  // atom_count Atoms
-
-  // Make these public so that they can be used as a general interface to
-  // the class.
+  /// An Atom defines the form of the data in the accelerator table.
+  /// Conceptually it is a column in the accelerator consisting of a type and a
+  /// specification of the form of its data.
   struct Atom {
-    uint16_t type; // enum AtomType
-    uint16_t form; // DWARF DW_FORM_ defines
+    /// Atom Type.
+    const uint16_t Type;
+    /// DWARF Form.
+    const uint16_t Form;
 
-    constexpr Atom(uint16_t type, uint16_t form) : type(type), form(form) {}
+    constexpr Atom(uint16_t Type, uint16_t Form) : Type(Type), Form(Form) {}
 
 #ifndef NDEBUG
-    void print(raw_ostream &OS) {
-      OS << "Type: " << dwarf::AtomTypeString(type) << "\n"
-         << "Form: " << dwarf::FormEncodingString(form) << "\n";
+    void print(raw_ostream &OS) const {
+      OS << "Type: " << dwarf::AtomTypeString(Type) << "\n"
+         << "Form: " << dwarf::FormEncodingString(Form) << "\n";
     }
 
-    void dump() { print(dbgs()); }
+    void dump() const { print(dbgs()); }
 #endif
   };
 
 private:
-  struct TableHeaderData {
-    uint32_t die_offset_base;
+  /// The HeaderData describes the structure of the accelerator table through a
+  /// list of Atoms.
+  struct HeaderData {
+    /// In the case of data that is referenced via DW_FORM_ref_* the offset
+    /// base is used to describe the offset for all forms in the list of atoms.
+    uint32_t DieOffsetBase;
+
     SmallVector<Atom, 3> Atoms;
 
-    TableHeaderData(ArrayRef<Atom> AtomList, uint32_t offset = 0)
-        : die_offset_base(offset), Atoms(AtomList.begin(), AtomList.end()) {}
+    HeaderData(ArrayRef<Atom> AtomList, uint32_t Offset = 0)
+        : DieOffsetBase(Offset), Atoms(AtomList.begin(), AtomList.end()) {}
 
 #ifndef NDEBUG
-    void print(raw_ostream &OS) {
-      OS << "die_offset_base: " << die_offset_base << "\n";
-      for (size_t i = 0; i < Atoms.size(); i++)
-        Atoms[i].print(OS);
+    void print(raw_ostream &OS) const {
+      OS << "DIE Offset Base: " << DieOffsetBase << "\n";
+      for (auto Atom : Atoms)
+        Atom.print(OS);
     }
 
-    void dump() { print(dbgs()); }
+    void dump() const { print(dbgs()); }
 #endif
   };
 
-  // The data itself consists of a str_offset, a count of the DIEs in the
-  // hash and the offsets to the DIEs themselves.
-  // On disk each data section is ended with a 0 KeyType as the end of the
-  // hash chain.
-  // On output this looks like:
-  // uint32_t str_offset
-  // uint32_t hash_data_count
-  // HashData[hash_data_count]
+  Header Header;
+  HeaderData HeaderData;
+
 public:
-  struct HashDataContents {
-    const DIE *Die;   // Offsets
-    char Flags; // Specific flags to output
+  /// The length of the header data is always going to be 4 + 4 + 4*NumAtoms.
+  AppleAccelTableHeader(ArrayRef<AppleAccelTableHeader::Atom> Atoms)
+      : Header(8 + (Atoms.size() * 4)), HeaderData(Atoms) {}
 
-    HashDataContents(const DIE *D, char Flags) : Die(D), Flags(Flags) {}
+  /// Update header with hash and bucket count.
+  void setBucketAndHashCount(uint32_t HashCount);
+
+  uint32_t getHashCount() const { return Header.HashCount; }
+  uint32_t getBucketCount() const { return Header.BucketCount; }
+
+  /// Emits the header via the AsmPrinter.
+  void emit(AsmPrinter *);
 
 #ifndef NDEBUG
-    void print(raw_ostream &OS) const {
-      OS << "  Offset: " << Die->getOffset() << "\n"
-         << "  Tag: " << dwarf::TagString(Die->getTag()) << "\n"
-         << "  Flags: " << Flags << "\n";
-    }
+    Header.print(OS);
+    HeaderData.print(OS);
+
+  void dump() const { print(dbgs()); }
 #endif
-  };
 
-private:
-  // String Data
+/// Interface which the different types of accelerator table data have to
+/// conform.
+class AppleAccelTableData {
+public:
+  virtual ~AppleAccelTableData() = default;
+
+  virtual void emit(AsmPrinter *Asm) const = 0;
+
+  bool operator<(const AppleAccelTableData &Other) const {
+    return order() < Other.order();
+  }
+
+#ifndef NDEBUG
+  virtual void print(raw_ostream &OS) const = 0;
+#endif
+protected:
+  virtual uint64_t order() const;
+};
+
+/// Apple-style accelerator table.
+class AppleAccelTable {
   struct DataArray {
     DwarfStringPoolEntryRef Name;
-    std::vector<HashDataContents *> Values;
+    std::vector<AppleAccelTableData *> Values;
   };
 
   friend struct HashData;
 
   struct HashData {
     StringRef Str;
     uint32_t HashValue;
     MCSymbol *Sym;
-    DwarfAccelTable::DataArray &Data; // offsets
+    AppleAccelTable::DataArray &Data;
 
-    HashData(StringRef S, DwarfAccelTable::DataArray &Data)
+    HashData(StringRef S, AppleAccelTable::DataArray &Data)
         : Str(S), Data(Data) {
       HashValue = dwarf::djbHash(S);
     }
 
 #ifndef NDEBUG
     void print(raw_ostream &OS) {
       OS << "Name: " << Str << "\n";
       OS << "  Hash Value: " << format("0x%x", HashValue) << "\n";
       OS << "  Symbol: ";
       if (Sym)
         OS << *Sym;
       else
         OS << "<none>";
       OS << "\n";
-      for (HashDataContents *C : Data.Values) {
-        OS << "  Offset: " << C->Die->getOffset() << "\n";
-        OS << "  Tag: " << dwarf::TagString(C->Die->getTag()) << "\n";
-        OS << "  Flags: " << C->Flags << "\n";
-      }
+      for (auto *Value : Data.Values)
+        Value->print(OS);
     }
 
     void dump() { print(dbgs()); }
 #endif
   };
 
-  // Internal Functions
-  void EmitHeader(AsmPrinter *);
-  void EmitBuckets(AsmPrinter *);
-  void EmitHashes(AsmPrinter *);
+  /// Emits the header for the table via the AsmPrinter.
+  void emitHeader(AsmPrinter *Asm);
+
+  /// Helper function to compute the number of buckets needed based on the
+  /// number of unique hashes.
+  void computeBucketCount();
+
+  /// Walk through and emit the buckets for the table. Each index is an offset
+  /// into the list of hashes.
+  void emitBuckets(AsmPrinter *);
+
+  /// Walk through the buckets and emit the individual hashes for each bucket.
+  void emitHashes(AsmPrinter *);
+
+  /// Walk through the buckets and emit the individual offsets for each element
+  /// in each bucket. This is done via a symbol subtraction from the beginning
+  /// of the section. The non-section symbol will be output later when we emit
+  /// the actual data.
   void emitOffsets(AsmPrinter *, const MCSymbol *);
-  void EmitData(AsmPrinter *, DwarfDebug *D);
 
-  // Allocator for HashData and HashDataContents.
+  /// Walk through the buckets and emit the full data for each element in the
+  /// bucket. For the string case emit the dies and the various offsets.
+  /// Terminate each HashData bucket with 0.
+  void emitData(AsmPrinter *);
+
+  /// Allocator for HashData and Values.
   BumpPtrAllocator Allocator;
 
-  // Output Variables
-  TableHeader Header;
-  TableHeaderData HeaderData;
+  /// Header containing both the header and header data.
+  AppleAccelTableHeader Header;
   std::vector<HashData *> Data;
 
   using StringEntries = StringMap<DataArray, BumpPtrAllocator &>;
-
   StringEntries Entries;
 
-  // Buckets/Hashes/Offsets
   using HashList = std::vector<HashData *>;
+  HashList Hashes;
+
   using BucketList = std::vector<HashList>;
   BucketList Buckets;
-  HashList Hashes;
 
-  // Public Implementation
 public:
-  DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom>);
-  DwarfAccelTable(const DwarfAccelTable &) = delete;
-  DwarfAccelTable &operator=(const DwarfAccelTable &) = delete;
-
-  void AddName(DwarfStringPoolEntryRef Name, const DIE *Die, char Flags = 0);
-  void FinalizeTable(AsmPrinter *, StringRef);
-  void emit(AsmPrinter *, const MCSymbol *, DwarfDebug *);
+  AppleAccelTable(ArrayRef<AppleAccelTableHeader::Atom> Atoms)
+      : Header(Atoms), Entries(Allocator) {}
+
+  AppleAccelTable(const AppleAccelTable &) = delete;
+  AppleAccelTable &operator=(const AppleAccelTable &) = delete;
+
+  template <typename DataT>
+  void addName(DwarfStringPoolEntryRef Name, typename DataT::DataType D);
+
+  void finalizeTable(AsmPrinter *, StringRef);
+
+  void emit(AsmPrinter *Asm, const MCSymbol *SecBegin) {
+    emitHeader(Asm);
+    emitBuckets(Asm);
+    emitHashes(Asm);
+    emitOffsets(Asm, SecBegin);
+    emitData(Asm);
+  }
+
 #ifndef NDEBUG
-  void print(raw_ostream &OS);
-  void dump() { print(dbgs()); }
+  void print(raw_ostream &OS) const {
+    // Print Header.
+    Header.print(OS);
+
+    // Print Content.
+    OS << "Entries: \n";
+    for (const auto &Entry : Entries) {
+      OS << "Name: " << Entry.first() << "\n";
+      for (auto *V : Entry.second.Values)
+        V->print(OS);
+    }
+
+    OS << "Buckets and Hashes: \n";
+    for (auto &Bucket : Buckets)
+      for (auto &Hash : Bucket)
+        Hash->print(OS);
+
+    OS << "Data: \n";
+    for (auto &D : Data)
+      D->print(OS);
+  }
+  void dump() const { print(dbgs()); }
+#endif
+};
+
+template <typename DataT>
+void AppleAccelTable::addName(DwarfStringPoolEntryRef Name,
+                              typename DataT::DataType D) {
+  assert(Data.empty() && "Already finalized!");
+  // If the string is in the list already then add this die to the list
+  // otherwise add a new one.
+  DataArray &DA = Entries[Name.getString()];
+  assert(!DA.Name || DA.Name == Name);
+  DA.Name = Name;
+  DA.Values.push_back(new (Allocator) DataT(D));
+}
+
+/// Accelerator table data implementation for simple accelerator tables with
+/// just a DIE reference.
+class AppleAccelTableOffsetData : public AppleAccelTableData {
+public:
+  typedef const DIE *DataType;
+
+  AppleAccelTableOffsetData(DataType D) : Die(D) {}
+
+  void emit(AsmPrinter *Asm) const override;
+
+  static constexpr AppleAccelTableHeader::Atom Atoms[] = {
+      AppleAccelTableHeader::Atom(dwarf::DW_ATOM_die_offset,
+                                  dwarf::DW_FORM_data4)};
+
+#ifndef NDEBUG
+  void print(raw_ostream &OS) const override {
+    OS << "  Offset: " << Die->getOffset() << "\n";
+  }
+
+#endif
+protected:
+  uint64_t order() const override { return Die->getOffset(); }
+
+  DataType Die;
+};
+
+/// Accelerator table data implementation for type accelerator tables.
+class AppleAccelTableTypeData : public AppleAccelTableOffsetData {
+public:
+  AppleAccelTableTypeData(const DIE *D) : AppleAccelTableOffsetData(D) {}
+
+  void emit(AsmPrinter *Asm) const override;
+
+  static constexpr AppleAccelTableHeader::Atom Atoms[] = {
+      AppleAccelTableHeader::Atom(dwarf::DW_ATOM_die_offset,
+                                  dwarf::DW_FORM_data4),
+      AppleAccelTableHeader::Atom(dwarf::DW_ATOM_die_tag, dwarf::DW_FORM_data2),
+      AppleAccelTableHeader::Atom(dwarf::DW_ATOM_type_flags,
+                                  dwarf::DW_FORM_data1)};
+
+#ifndef NDEBUG
+  void print(raw_ostream &OS) const override {
+    OS << "  Offset: " << Die->getOffset() << "\n";
+    OS << "  Tag: " << dwarf::TagString(Die->getTag()) << "\n";
+  }
 #endif
 };
 
 } // end namespace llvm
 
 #endif // LLVM_LIB_CODEGEN_ASMPRINTER_DWARFACCELTABLE_H

lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp

 #include "llvm/ADT/Twine.h"
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/CodeGen/DIE.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
-#include <cassert>
 #include <cstddef>
 #include <cstdint>
-#include <iterator>
 #include <limits>
 #include <vector>
 
 using namespace llvm;
 
-// The length of the header data is always going to be 4 + 4 + 4*NumAtoms.
-DwarfAccelTable::DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom> atomList)
-    : Header(8 + (atomList.size() * 4)), HeaderData(atomList),
-      Entries(Allocator) {}
-
-void DwarfAccelTable::AddName(DwarfStringPoolEntryRef Name, const DIE *die,
-                              char Flags) {
-  assert(Data.empty() && "Already finalized!");
-  // If the string is in the list already then add this die to the list
-  // otherwise add a new one.
-  DataArray &DIEs = Entries[Name.getString()];
-  assert(!DIEs.Name || DIEs.Name == Name);
-  DIEs.Name = Name;
-  DIEs.Values.push_back(new (Allocator) HashDataContents(die, Flags));
-}
-
-void DwarfAccelTable::ComputeBucketCount() {
-  // First get the number of unique hashes.
-  std::vector<uint32_t> uniques(Data.size());
-  for (size_t i = 0, e = Data.size(); i < e; ++i)
-    uniques[i] = Data[i]->HashValue;
-  array_pod_sort(uniques.begin(), uniques.end());
-  std::vector<uint32_t>::iterator p =
-      std::unique(uniques.begin(), uniques.end());
-  uint32_t num = std::distance(uniques.begin(), p);
-
-  // Then compute the bucket size, minimum of 1 bucket.
-  if (num > 1024)
-    Header.bucket_count = num / 4;
-  else if (num > 16)
-    Header.bucket_count = num / 2;
-  else
-    Header.bucket_count = num > 0 ? num : 1;
-
-  Header.hashes_count = num;
-}
-
-// compareDIEs - comparison predicate that sorts DIEs by their offset.
-static bool compareDIEs(const DwarfAccelTable::HashDataContents *A,
-                        const DwarfAccelTable::HashDataContents *B) {
-  return A->Die->getOffset() < B->Die->getOffset();
-}
-
-void DwarfAccelTable::FinalizeTable(AsmPrinter *Asm, StringRef Prefix) {
-  // Create the individual hash data outputs.
-  Data.reserve(Entries.size());
-  for (StringMap<DataArray>::iterator EI = Entries.begin(), EE = Entries.end();
-       EI != EE; ++EI) {
-
-    // Unique the entries.
-    std::stable_sort(EI->second.Values.begin(), EI->second.Values.end(), compareDIEs);
-    EI->second.Values.erase(
-        std::unique(EI->second.Values.begin(), EI->second.Values.end()),
-        EI->second.Values.end());
-
-    HashData *Entry = new (Allocator) HashData(EI->getKey(), EI->second);
-    Data.push_back(Entry);
-  }
-
-  // Figure out how many buckets we need, then compute the bucket
-  // contents and the final ordering. We'll emit the hashes and offsets
-  // by doing a walk during the emission phase. We add temporary
-  // symbols to the data so that we can reference them during the offset
-  // later, we'll emit them when we emit the data.
-  ComputeBucketCount();
-
-  // Compute bucket contents and final ordering.
-  Buckets.resize(Header.bucket_count);
-  for (size_t i = 0, e = Data.size(); i < e; ++i) {
-    uint32_t bucket = Data[i]->HashValue % Header.bucket_count;
-    Buckets[bucket].push_back(Data[i]);
-    Data[i]->Sym = Asm->createTempSymbol(Prefix);
-  }
-
-  // Sort the contents of the buckets by hash value so that hash
-  // collisions end up together. Stable sort makes testing easier and
-  // doesn't cost much more.
-  for (size_t i = 0; i < Buckets.size(); ++i)
-    std::stable_sort(Buckets[i].begin(), Buckets[i].end(),
-                     [] (HashData *LHS, HashData *RHS) {
-                       return LHS->HashValue < RHS->HashValue;
-                     });
-}
-
-// Emits the header for the table via the AsmPrinter.
-void DwarfAccelTable::EmitHeader(AsmPrinter *Asm) {
+void AppleAccelTableHeader::emit(AsmPrinter *Asm) {
+  // Emit Header.
   Asm->OutStreamer->AddComment("Header Magic");
-  Asm->EmitInt32(Header.magic);
+  Asm->EmitInt32(Header.Magic);
   Asm->OutStreamer->AddComment("Header Version");
-  Asm->EmitInt16(Header.version);
+  Asm->EmitInt16(Header.Version);
   Asm->OutStreamer->AddComment("Header Hash Function");
-  Asm->EmitInt16(Header.hash_function);
+  Asm->EmitInt16(Header.HashFunction);
   Asm->OutStreamer->AddComment("Header Bucket Count");
-  Asm->EmitInt32(Header.bucket_count);
+  Asm->EmitInt32(Header.BucketCount);
   Asm->OutStreamer->AddComment("Header Hash Count");
-  Asm->EmitInt32(Header.hashes_count);
+  Asm->EmitInt32(Header.HashCount);
   Asm->OutStreamer->AddComment("Header Data Length");
-  Asm->EmitInt32(Header.header_data_len);
+  Asm->EmitInt32(Header.HeaderDataLength);
+
+  //  Emit Header Data
   Asm->OutStreamer->AddComment("HeaderData Die Offset Base");
-  Asm->EmitInt32(HeaderData.die_offset_base);
+  Asm->EmitInt32(HeaderData.DieOffsetBase);
   Asm->OutStreamer->AddComment("HeaderData Atom Count");
   Asm->EmitInt32(HeaderData.Atoms.size());
+
   for (size_t i = 0; i < HeaderData.Atoms.size(); i++) {
     Atom A = HeaderData.Atoms[i];
-    Asm->OutStreamer->AddComment(dwarf::AtomTypeString(A.type));
-    Asm->EmitInt16(A.type);
-    Asm->OutStreamer->AddComment(dwarf::FormEncodingString(A.form));
-    Asm->EmitInt16(A.form);
-  }
+    Asm->OutStreamer->AddComment(dwarf::AtomTypeString(A.Type));
+    Asm->EmitInt16(A.Type);
+    Asm->OutStreamer->AddComment(dwarf::FormEncodingString(A.Form));
+    Asm->EmitInt16(A.Form);
+  }
+
+void AppleAccelTableHeader::setBucketAndHashCount(uint32_t HashCount) {
+  if (HashCount > 1024)
+    Header.BucketCount = HashCount / 4;
+  else if (HashCount > 16)
+    Header.BucketCount = HashCount / 2;
+  else
+    Header.BucketCount = HashCount > 0 ? HashCount : 1;
+
+  Header.HashCount = HashCount;
 }
 
-// Walk through and emit the buckets for the table. Each index is
-// an offset into the list of hashes.
-void DwarfAccelTable::EmitBuckets(AsmPrinter *Asm) {
+constexpr AppleAccelTableHeader::Atom AppleAccelTableTypeData::Atoms[];
+constexpr AppleAccelTableHeader::Atom AppleAccelTableOffsetData::Atoms[];
+
+void AppleAccelTable::emitHeader(AsmPrinter *Asm) { Header.emit(Asm); }
+
+void AppleAccelTable::emitBuckets(AsmPrinter *Asm) {
   unsigned index = 0;
   for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
     Asm->OutStreamer->AddComment("Bucket " + Twine(i));
     if (!Buckets[i].empty())
       Asm->EmitInt32(index);
     else
       Asm->EmitInt32(std::numeric_limits<uint32_t>::max());
-    // Buckets point in the list of hashes, not to the data. Do not
-    // increment the index multiple times in case of hash collisions.
+    // Buckets point in the list of hashes, not to the data. Do not increment
+    // the index multiple times in case of hash collisions.
     uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
     for (auto *HD : Buckets[i]) {
       uint32_t HashValue = HD->HashValue;
       if (PrevHash != HashValue)
         ++index;
       PrevHash = HashValue;
     }
   }
 }
 
-// Walk through the buckets and emit the individual hashes for each
-// bucket.
-void DwarfAccelTable::EmitHashes(AsmPrinter *Asm) {
+void AppleAccelTable::emitHashes(AsmPrinter *Asm) {
   uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
-  for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
-    for (HashList::const_iterator HI = Buckets[i].begin(),
-                                  HE = Buckets[i].end();
-         HI != HE; ++HI) {
-      uint32_t HashValue = (*HI)->HashValue;
+  unsigned BucketIdx = 0;
+  for (auto &Bucket : Buckets) {
+    for (auto &Hash : Bucket) {
+      uint32_t HashValue = Hash->HashValue;
       if (PrevHash == HashValue)
         continue;
-      Asm->OutStreamer->AddComment("Hash in Bucket " + Twine(i));
+      Asm->OutStreamer->AddComment("Hash in Bucket " + Twine(BucketIdx));
       Asm->EmitInt32(HashValue);
       PrevHash = HashValue;
     }
+    BucketIdx++;
   }
 }
 
-// Walk through the buckets and emit the individual offsets for each
-// element in each bucket. This is done via a symbol subtraction from the
-// beginning of the section. The non-section symbol will be output later
-// when we emit the actual data.
-void DwarfAccelTable::emitOffsets(AsmPrinter *Asm, const MCSymbol *SecBegin) {
+void AppleAccelTable::emitOffsets(AsmPrinter *Asm, const MCSymbol *SecBegin) {
   uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
   for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
-    for (HashList::const_iterator HI = Buckets[i].begin(),
-                                  HE = Buckets[i].end();
-         HI != HE; ++HI) {
+    for (auto HI = Buckets[i].begin(), HE = Buckets[i].end(); HI != HE; ++HI) {
       uint32_t HashValue = (*HI)->HashValue;
       if (PrevHash == HashValue)
         continue;
       PrevHash = HashValue;
       Asm->OutStreamer->AddComment("Offset in Bucket " + Twine(i));
       MCContext &Context = Asm->OutStreamer->getContext();
       const MCExpr *Sub = MCBinaryExpr::createSub(
           MCSymbolRefExpr::create((*HI)->Sym, Context),
           MCSymbolRefExpr::create(SecBegin, Context), Context);
       Asm->OutStreamer->EmitValue(Sub, sizeof(uint32_t));
     }
   }
 }
 
-// Walk through the buckets and emit the full data for each element in
-// the bucket. For the string case emit the dies and the various offsets.
-// Terminate each HashData bucket with 0.
-void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfDebug *D) {
+void AppleAccelTable::emitData(AsmPrinter *Asm) {
   for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
     uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
-    for (HashList::const_iterator HI = Buckets[i].begin(),
-                                  HE = Buckets[i].end();
-         HI != HE; ++HI) {
-      // Terminate the previous entry if there is no hash collision
-      // with the current one.
+    for (auto &Hash : Buckets[i]) {
+      // Terminate the previous entry if there is no hash collision with the
+      // current one.
       if (PrevHash != std::numeric_limits<uint64_t>::max() &&
-          PrevHash != (*HI)->HashValue)
+          PrevHash != Hash->HashValue)
         Asm->EmitInt32(0);
       // Remember to emit the label for our offset.
-      Asm->OutStreamer->EmitLabel((*HI)->Sym);
-      Asm->OutStreamer->AddComment((*HI)->Str);
-      Asm->emitDwarfStringOffset((*HI)->Data.Name);
+      Asm->OutStreamer->EmitLabel(Hash->Sym);
+      Asm->OutStreamer->AddComment(Hash->Str);
+      Asm->emitDwarfStringOffset(Hash->Data.Name);
       Asm->OutStreamer->AddComment("Num DIEs");
-      Asm->EmitInt32((*HI)->Data.Values.size());
-      for (HashDataContents *HD : (*HI)->Data.Values) {
-        // Emit the DIE offset
-        Asm->EmitInt32(HD->Die->getDebugSectionOffset());
-        // If we have multiple Atoms emit that info too.
-        // FIXME: A bit of a hack, we either emit only one atom or all info.
-        if (HeaderData.Atoms.size() > 1) {
-          Asm->EmitInt16(HD->Die->getTag());
-          Asm->EmitInt8(HD->Flags);
-        }
-      }
-      PrevHash = (*HI)->HashValue;
+      Asm->EmitInt32(Hash->Data.Values.size());
+      for (const auto *V : Hash->Data.Values) {
+        V->emit(Asm);
+      PrevHash = Hash->HashValue;
     }
     // Emit the final end marker for the bucket.
     if (!Buckets[i].empty())
       Asm->EmitInt32(0);
   }
 }
 
-// Emit the entire data structure to the output file.
-void DwarfAccelTable::emit(AsmPrinter *Asm, const MCSymbol *SecBegin,
-                           DwarfDebug *D) {
-  // Emit the header.
-  EmitHeader(Asm);
-
-  // Emit the buckets.
-  EmitBuckets(Asm);
-
-  // Emit the hashes.
-  EmitHashes(Asm);
-
-  // Emit the offsets.
-  emitOffsets(Asm, SecBegin);
-
-  // Emit the hash data.
-  EmitData(Asm, D);
-}
-
-#ifndef NDEBUG
-void DwarfAccelTable::print(raw_ostream &OS) {
-  Header.print(OS);
-  HeaderData.print(OS);
-
-  OS << "Entries: \n";
-  for (StringMap<DataArray>::const_iterator EI = Entries.begin(),
-                                            EE = Entries.end();
-       EI != EE; ++EI) {
-    OS << "Name: " << EI->getKeyData() << "\n";
-    for (HashDataContents *HD : EI->second.Values)
-      HD->print(OS);
-  }
-
-  OS << "Buckets and Hashes: \n";
-  for (size_t i = 0, e = Buckets.size(); i < e; ++i)
-    for (HashList::const_iterator HI = Buckets[i].begin(),
-                                  HE = Buckets[i].end();
-         HI != HE; ++HI)
-      (*HI)->print(OS);
-
-  OS << "Data: \n";
-  for (std::vector<HashData *>::const_iterator DI = Data.begin(),
-                                               DE = Data.end();
-       DI != DE; ++DI)
-    (*DI)->print(OS);
+void AppleAccelTable::computeBucketCount() {
+  // First get the number of unique hashes.
+  std::vector<uint32_t> uniques(Data.size());
+  for (size_t i = 0, e = Data.size(); i < e; ++i)
+    uniques[i] = Data[i]->HashValue;
+  array_pod_sort(uniques.begin(), uniques.end());
+  std::vector<uint32_t>::iterator p =
+      std::unique(uniques.begin(), uniques.end());
+
+  // Compute the hashes count and use it to set that together with the bucket
+  // count in the header.
+  Header.setBucketAndHashCount(std::distance(uniques.begin(), p));
+}
+
+void AppleAccelTable::finalizeTable(AsmPrinter *Asm, StringRef Prefix) {
+  // Create the individual hash data outputs.
+  Data.reserve(Entries.size());
+  for (auto &E : Entries) {
+    // Unique the entries.
+    std::stable_sort(E.second.Values.begin(), E.second.Values.end(),
+                     [](const AppleAccelTableData *A,
+                        const AppleAccelTableData *B) { return *A < *B; });
+    E.second.Values.erase(
+        std::unique(E.second.Values.begin(), E.second.Values.end()),
+        E.second.Values.end());
+
+    HashData *Entry = new (Allocator) HashData(E.first(), E.second);
+    Data.push_back(Entry);
+  }
+
+  // Figure out how many buckets we need, then compute the bucket contents and
+  // the final ordering. We'll emit the hashes and offsets by doing a walk
+  // during the emission phase. We add temporary symbols to the data so that we
+  // can reference them during the offset later, we'll emit them when we emit
+  // the data.
+  computeBucketCount();
+
+  // Compute bucket contents and final ordering.
+  Buckets.resize(Header.getBucketCount());
+  for (auto &D : Data) {
+    uint32_t bucket = D->HashValue % Header.getBucketCount();
+    Buckets[bucket].push_back(D);
+    D->Sym = Asm->createTempSymbol(Prefix);
+  }
+
+  // Sort the contents of the buckets by hash value so that hash collisions end
+  // up together. Stable sort makes testing easier and doesn't cost much more.
+  for (auto &Bucket : Buckets)
+    std::stable_sort(Bucket.begin(), Bucket.end(),
+                     [](HashData *LHS, HashData *RHS) {
+                       return LHS->HashValue < RHS->HashValue;
+                     });
+}
+
+void AppleAccelTableOffsetData::emit(AsmPrinter *Asm) const {
+  Asm->EmitInt32(Die->getDebugSectionOffset());
+}
+
+void AppleAccelTableTypeData::emit(AsmPrinter *Asm) const {
+  Asm->EmitInt32(Die->getDebugSectionOffset());
+  Asm->EmitInt16(Die->getTag());
+  Asm->EmitInt8(0);
 }
-#endif

lib/CodeGen/AsmPrinter/DwarfDebug.h

class DwarfDebug : public DebugHandlerBase {
   /// @}
 
   /// True iff there are multiple CUs in this module.
   bool SingleCU;
   bool IsDarwin;
 
   AddressPool AddrPool;
 
-  DwarfAccelTable AccelNames;
-  DwarfAccelTable AccelObjC;
-  DwarfAccelTable AccelNamespace;
-  DwarfAccelTable AccelTypes;
+  AppleAccelTable AccelNames;
+  AppleAccelTable AccelObjC;
+  AppleAccelTable AccelNamespace;
+  AppleAccelTable AccelTypes;
 
   // Identify a debugger for "tuning" the debug info.
   DebuggerKind DebuggerTuning = DebuggerKind::Default;
 
   MCDwarfDwoLineTable *getDwoLineTable(const DwarfCompileUnit &);
 
   const SmallVectorImpl<std::unique_ptr<DwarfCompileUnit>> &getUnits() {
     return InfoHolder.getUnits();
class DwarfDebug : public DebugHandlerBase {
 
   /// Emit the debug info section.
   void emitDebugInfo();
 
   /// Emit the abbreviation section.
   void emitAbbreviations();
 
   /// Emit a specified accelerator table.
-  void emitAccel(DwarfAccelTable &Accel, MCSection *Section,
+  void emitAccel(AppleAccelTable &Accel, MCSection *Section,
                  StringRef TableName);
 
   /// Emit visible names into a hashed accelerator table section.
   void emitAccelNames();
 
   /// Emit objective C classes and categories into a hashed
   /// accelerator table section.
   void emitAccelObjC();

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

void DbgVariable::addMMIEntry(const DbgVariable &V) {
   assert((FrameIndexExprs.size() == 1 ||
           llvm::all_of(FrameIndexExprs,
                        [](FrameIndexExpr &FIE) {
                          return FIE.Expr && FIE.Expr->isFragment();
                        })) &&
          "conflicting locations for variable");
 }
 
-static const DwarfAccelTable::Atom TypeAtoms[] = {
-    DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset, dwarf::DW_FORM_data4),
-    DwarfAccelTable::Atom(dwarf::DW_ATOM_die_tag, dwarf::DW_FORM_data2),
-    DwarfAccelTable::Atom(dwarf::DW_ATOM_type_flags, dwarf::DW_FORM_data1)};
-
 DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
     : DebugHandlerBase(A), DebugLocs(A->OutStreamer->isVerboseAsm()),
       InfoHolder(A, "info_string", DIEValueAllocator),
       SkeletonHolder(A, "skel_string", DIEValueAllocator),
       IsDarwin(A->TM.getTargetTriple().isOSDarwin()),
-      AccelNames(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset,
-                                       dwarf::DW_FORM_data4)),
-      AccelObjC(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset,
-                                      dwarf::DW_FORM_data4)),
-      AccelNamespace(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset,
-                                           dwarf::DW_FORM_data4)),
-      AccelTypes(TypeAtoms) {
+      AccelNames(AppleAccelTableOffsetData::Atoms),
+      AccelObjC(AppleAccelTableOffsetData::Atoms),
+      AccelNamespace(AppleAccelTableOffsetData::Atoms),
+      AccelTypes(AppleAccelTableTypeData::Atoms) {
   const Triple &TT = Asm->TM.getTargetTriple();
 
   // Make sure we know our "debugger tuning."  The target option takes
   // precedence; fall back to triple-based defaults.
   if (Asm->TM.Options.DebuggerTuning != DebuggerKind::Default)
     DebuggerTuning = Asm->TM.Options.DebuggerTuning;
   else if (IsDarwin)
     DebuggerTuning = DebuggerKind::LLDB;

 
 // Emit the abbreviation section.
 void DwarfDebug::emitAbbreviations() {
   DwarfFile &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
 
   Holder.emitAbbrevs(Asm->getObjFileLowering().getDwarfAbbrevSection());
 }
 
-void DwarfDebug::emitAccel(DwarfAccelTable &Accel, MCSection *Section,
+void DwarfDebug::emitAccel(AppleAccelTable &Accel, MCSection *Section,
                            StringRef TableName) {
-  Accel.FinalizeTable(Asm, TableName);
+  Accel.finalizeTable(Asm, TableName);
   Asm->OutStreamer->SwitchSection(Section);
 
   // Emit the full data.
-  Accel.emit(Asm, Section->getBeginSymbol(), this);
+  Accel.emit(Asm, Section->getBeginSymbol());
 }
 
 // Emit visible names into a hashed accelerator table section.
 void DwarfDebug::emitAccelNames() {
   emitAccel(AccelNames, Asm->getObjFileLowering().getDwarfAccelNamesSection(),
             "Names");
 }
 

 
 // Accelerator table mutators - add each name along with its companion
 // DIE to the proper table while ensuring that the name that we're going
 // to reference is in the string table. We do this since the names we
 // add may not only be identical to the names in the DIE.
 void DwarfDebug::addAccelName(StringRef Name, const DIE &Die) {
   if (!useDwarfAccelTables())
     return;
-  AccelNames.AddName(InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
+  AccelNames.addName<AppleAccelTableOffsetData>(
+      InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
 }
 
 void DwarfDebug::addAccelObjC(StringRef Name, const DIE &Die) {
   if (!useDwarfAccelTables())
     return;
-  AccelObjC.AddName(InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
+  AccelObjC.addName<AppleAccelTableOffsetData>(
+      InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
 }
 
 void DwarfDebug::addAccelNamespace(StringRef Name, const DIE &Die) {
   if (!useDwarfAccelTables())
     return;
-  AccelNamespace.AddName(InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
+  AccelNamespace.addName<AppleAccelTableOffsetData>(
+      InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
 }
 
 void DwarfDebug::addAccelType(StringRef Name, const DIE &Die, char Flags) {
   if (!useDwarfAccelTables())
     return;
-  AccelTypes.AddName(InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
+  AccelTypes.addName<AppleAccelTableTypeData>(
+      InfoHolder.getStringPool().getEntry(*Asm, Name), &Die);
 }
 
 uint16_t DwarfDebug::getDwarfVersion() const {
   return Asm->OutStreamer->getContext().getDwarfVersion();
 }