DwarfDebug: emit type units immediately.

Rather than storing type units in a vector and emitting them at the end
of code generation, emit them immediately and destroy them, reclaiming the
memory we were using for their DIEs.

In one benchmark carried out against Chromium's 50 largest (by bitcode
file size) translation units, total peak memory consumption with type units
decreased by median 17%, or by 7% when compared against disabling type units.

Tested using check-{llvm,clang}, the GDB 7.5 test suite (with
'-fdebug-types-section') and by eyeballing llvm-dwarfdump output on those
Chromium translation units with split DWARF both disabled and enabled, and
verifying that the only changes were to addresses and abbreviation ordering.

Differential Revision: http://reviews.llvm.org/D17118

llvm-svn: 260578

10 files changed, 88 insertions, 85 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
index bf794f7f70f..2aaa85a5809 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -479,20 +479,6 @@ void DIEEntry::print(raw_ostream &O) const {
 }
 
 //===----------------------------------------------------------------------===//
-// DIETypeSignature Implementation
-//===----------------------------------------------------------------------===//
-void DIETypeSignature::EmitValue(const AsmPrinter *Asm,
-                                 dwarf::Form Form) const {
-  assert(Form == dwarf::DW_FORM_ref_sig8);
-  Asm->OutStreamer->EmitIntValue(Unit->getTypeSignature(), 8);
-}
-
-LLVM_DUMP_METHOD
-void DIETypeSignature::print(raw_ostream &O) const {
-  O << format("Type Unit: 0x%lx", Unit->getTypeSignature());
-}
-
-//===----------------------------------------------------------------------===//
 // DIELoc Implementation
 //===----------------------------------------------------------------------===//
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
index 02010654a6f..91684c2681c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
@@ -353,7 +353,6 @@ void DIEHash::hashAttribute(DIEValue Value, dwarf::Tag Tag) {
   case DIEValue::isExpr:
   case DIEValue::isLabel:
   case DIEValue::isDelta:
-  case DIEValue::isTypeSignature:
     llvm_unreachable("Add support for additional value types.");
   }
 }
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index cad3b2a464c..9dd5040ce81 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -19,7 +19,7 @@ namespace llvm {
 DwarfCompileUnit::DwarfCompileUnit(unsigned UID, const DICompileUnit *Node,
                                    AsmPrinter *A, DwarfDebug *DW,
                                    DwarfFile *DWU)
-    : DwarfUnit(UID, dwarf::DW_TAG_compile_unit, Node, A, DW, DWU),
+    : DwarfUnit(dwarf::DW_TAG_compile_unit, Node, A, DW, DWU), UniqueID(UID),
       Skeleton(nullptr), BaseAddress(nullptr) {
   insertDIE(Node, &getUnitDie());
   MacroLabelBegin = Asm->createTempSymbol("cu_macro_begin");
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
index 2c89f5006c2..bacf87d95c4 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -29,6 +29,12 @@ class MCSymbol;
 class LexicalScope;
 
 class DwarfCompileUnit : public DwarfUnit {
+  /// A numeric ID unique among all CUs in the module
+  unsigned UniqueID;
+
+  /// Offset of the UnitDie from beginning of debug info section.
+  unsigned DebugInfoOffset = 0;
+
   /// The attribute index of DW_AT_stmt_list in the compile unit DIE, avoiding
   /// the need to search for it in applyStmtList.
   DIE::value_iterator StmtListValue;
@@ -77,6 +83,10 @@ public:
   DwarfCompileUnit(unsigned UID, const DICompileUnit *Node, AsmPrinter *A,
                    DwarfDebug *DW, DwarfFile *DWU);
 
+  unsigned getUniqueID() const { return UniqueID; }
+  unsigned getDebugInfoOffset() const { return DebugInfoOffset; }
+  void setDebugInfoOffset(unsigned DbgInfoOff) { DebugInfoOffset = DbgInfoOff; }
+
   DwarfCompileUnit *getSkeleton() const {
     return Skeleton;
   }
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index ec7329eafb7..9b376827e54 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1628,9 +1628,10 @@ void DwarfDebug::emitDebugARanges() {
   }
 
   // Sort the CU list (again, to ensure consistent output order).
-  std::sort(CUs.begin(), CUs.end(), [](const DwarfUnit *A, const DwarfUnit *B) {
-    return A->getUniqueID() < B->getUniqueID();
-  });
+  std::sort(CUs.begin(), CUs.end(),
+            [](const DwarfCompileUnit *A, const DwarfCompileUnit *B) {
+              return A->getUniqueID() < B->getUniqueID();
+            });
 
   // Emit an arange table for each CU we used.
   for (DwarfCompileUnit *CU : CUs) {
@@ -1793,7 +1794,7 @@ void DwarfDebug::emitDebugMacinfo() {
 // DWARF5 Experimental Separate Dwarf emitters.
 
 void DwarfDebug::initSkeletonUnit(const DwarfUnit &U, DIE &Die,
-                                  std::unique_ptr<DwarfUnit> NewU) {
+                                  std::unique_ptr<DwarfCompileUnit> NewU) {
   NewU->addString(Die, dwarf::DW_AT_GNU_dwo_name,
                   U.getCUNode()->getSplitDebugFilename());
 
@@ -1882,21 +1883,19 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
   if (!TypeUnitsUnderConstruction.empty() && AddrPool.hasBeenUsed())
     return;
 
-  const DwarfTypeUnit *&TU = DwarfTypeUnits[CTy];
-  if (TU) {
-    CU.addDIETypeSignature(RefDie, *TU);
+  auto Ins = TypeSignatures.insert(std::make_pair(CTy, 0));
+  if (!Ins.second) {
+    CU.addDIETypeSignature(RefDie, Ins.first->second);
     return;
   }
 
   bool TopLevelType = TypeUnitsUnderConstruction.empty();
   AddrPool.resetUsedFlag();
 
-  auto OwnedUnit = make_unique<DwarfTypeUnit>(
-      InfoHolder.getUnits().size() + TypeUnitsUnderConstruction.size(), CU, Asm,
-      this, &InfoHolder, getDwoLineTable(CU));
+  auto OwnedUnit = make_unique<DwarfTypeUnit>(CU, Asm, this, &InfoHolder,
+                                              getDwoLineTable(CU));
   DwarfTypeUnit &NewTU = *OwnedUnit;
   DIE &UnitDie = NewTU.getUnitDie();
-  TU = &NewTU;
   TypeUnitsUnderConstruction.push_back(
       std::make_pair(std::move(OwnedUnit), CTy));
 
@@ -1905,6 +1904,7 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
 
   uint64_t Signature = makeTypeSignature(Identifier);
   NewTU.setTypeSignature(Signature);
+  Ins.first->second = Signature;
 
   if (useSplitDwarf())
     NewTU.initSection(Asm->getObjFileLowering().getDwarfTypesDWOSection());
@@ -1928,7 +1928,7 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
       // This is pessimistic as some of these types might not be dependent on
       // the type that used an address.
       for (const auto &TU : TypeUnitsToAdd)
-        DwarfTypeUnits.erase(TU.second);
+        TypeSignatures.erase(TU.second);
 
       // Construct this type in the CU directly.
       // This is inefficient because all the dependent types will be rebuilt
@@ -1940,10 +1940,12 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
 
     // If the type wasn't dependent on fission addresses, finish adding the type
     // and all its dependent types.
-    for (auto &TU : TypeUnitsToAdd)
-      InfoHolder.addUnit(std::move(TU.first));
+    for (auto &TU : TypeUnitsToAdd) {
+      InfoHolder.computeSizeAndOffsetsForUnit(TU.first.get());
+      InfoHolder.emitUnit(TU.first.get(), useSplitDwarf());
+    }
   }
-  CU.addDIETypeSignature(RefDie, NewTU);
+  CU.addDIETypeSignature(RefDie, Signature);
 }
 
 // Accelerator table mutators - add each name along with its companion
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 720507a60d8..31303e4ba38 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -235,9 +235,9 @@ class DwarfDebug : public DebugHandlerBase {
   /// Holders for the various debug information flags that we might need to
   /// have exposed. See accessor functions below for description.
 
-  /// Map from MDNodes for user-defined types to the type units that
-  /// describe them.
-  DenseMap<const MDNode *, const DwarfTypeUnit *> DwarfTypeUnits;
+  /// Map from MDNodes for user-defined types to their type signatures. Also
+  /// used to keep track of which types we have emitted type units for.
+  DenseMap<const MDNode *, uint64_t> TypeSignatures;
 
   SmallVector<
       std::pair<std::unique_ptr<DwarfTypeUnit>, const DICompositeType *>, 1>
@@ -295,7 +295,7 @@ class DwarfDebug : public DebugHandlerBase {
 
   MCDwarfDwoLineTable *getDwoLineTable(const DwarfCompileUnit &);
 
-  const SmallVectorImpl<std::unique_ptr<DwarfUnit>> &getUnits() {
+  const SmallVectorImpl<std::unique_ptr<DwarfCompileUnit>> &getUnits() {
     return InfoHolder.getUnits();
   }
 
@@ -391,7 +391,7 @@ class DwarfDebug : public DebugHandlerBase {
 
   /// Initialize common features of skeleton units.
   void initSkeletonUnit(const DwarfUnit &U, DIE &Die,
-                        std::unique_ptr<DwarfUnit> NewU);
+                        std::unique_ptr<DwarfCompileUnit> NewU);
 
   /// Construct the split debug info compile unit for the debug info
   /// section.
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
index 51b27b462a7..e9fe98ab3cf 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "DwarfFile.h"
+#include "DwarfCompileUnit.h"
 #include "DwarfDebug.h"
 #include "DwarfUnit.h"
 #include "llvm/ADT/STLExtras.h"
@@ -50,22 +51,25 @@ DIEAbbrev &DwarfFile::assignAbbrevNumber(DIE &Die) {
   return *New;
 }
 
-void DwarfFile::addUnit(std::unique_ptr<DwarfUnit> U) {
+void DwarfFile::addUnit(std::unique_ptr<DwarfCompileUnit> U) {
   CUs.push_back(std::move(U));
 }
 
 // Emit the various dwarf units to the unit section USection with
 // the abbreviations going into ASection.
 void DwarfFile::emitUnits(bool UseOffsets) {
-  for (const auto &TheU : CUs) {
-    DIE &Die = TheU->getUnitDie();
-    MCSection *USection = TheU->getSection();
-    Asm->OutStreamer->SwitchSection(USection);
+  for (const auto &TheU : CUs)
+    emitUnit(TheU.get(), UseOffsets);
+}
 
-    TheU->emitHeader(UseOffsets);
+void DwarfFile::emitUnit(DwarfUnit *TheU, bool UseOffsets) {
+  DIE &Die = TheU->getUnitDie();
+  MCSection *USection = TheU->getSection();
+  Asm->OutStreamer->SwitchSection(USection);
 
-    Asm->emitDwarfDIE(Die);
-  }
+  TheU->emitHeader(UseOffsets);
+
+  Asm->emitDwarfDIE(Die);
 }
 
 // Compute the size and offset for each DIE.
@@ -77,17 +81,20 @@ void DwarfFile::computeSizeAndOffsets() {
   // DIE within each compile unit. All offsets are CU relative.
   for (const auto &TheU : CUs) {
     TheU->setDebugInfoOffset(SecOffset);
+    SecOffset += computeSizeAndOffsetsForUnit(TheU.get());
+  }
+}
 
-    // CU-relative offset is reset to 0 here.
-    unsigned Offset = sizeof(int32_t) +      // Length of Unit Info
-                      TheU->getHeaderSize(); // Unit-specific headers
+unsigned DwarfFile::computeSizeAndOffsetsForUnit(DwarfUnit *TheU) {
+  // CU-relative offset is reset to 0 here.
+  unsigned Offset = sizeof(int32_t) +      // Length of Unit Info
+                    TheU->getHeaderSize(); // Unit-specific headers
 
-    // EndOffset here is CU-relative, after laying out
-    // all of the CU DIE.
-    unsigned EndOffset = computeSizeAndOffset(TheU->getUnitDie(), Offset);
-    SecOffset += EndOffset;
-  }
+  // The return value here is CU-relative, after laying out
+  // all of the CU DIE.
+  return computeSizeAndOffset(TheU->getUnitDie(), Offset);
 }
+
 // Compute the size and offset of a DIE. The offset is relative to start of the
 // CU. It returns the offset after laying out the DIE.
 unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) {
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.h b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.h
index 291319c05fc..8b4e3347265 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.h
@@ -25,6 +25,7 @@
 namespace llvm {
 class AsmPrinter;
 class DbgVariable;
+class DwarfCompileUnit;
 class DwarfUnit;
 class DIEAbbrev;
 class MCSymbol;
@@ -47,7 +48,7 @@ class DwarfFile {
   std::vector<DIEAbbrev *> Abbreviations;
 
   // A pointer to all units in the section.
-  SmallVector<std::unique_ptr<DwarfUnit>, 1> CUs;
+  SmallVector<std::unique_ptr<DwarfCompileUnit>, 1> CUs;
 
   DwarfStringPool StrPool;
 
@@ -67,7 +68,9 @@ public:
 
   ~DwarfFile();
 
-  const SmallVectorImpl<std::unique_ptr<DwarfUnit>> &getUnits() { return CUs; }
+  const SmallVectorImpl<std::unique_ptr<DwarfCompileUnit>> &getUnits() {
+    return CUs;
+  }
 
   /// \brief Compute the size and offset of a DIE given an incoming Offset.
   unsigned computeSizeAndOffset(DIE &Die, unsigned Offset);
@@ -75,6 +78,10 @@ public:
   /// \brief Compute the size and offset of all the DIEs.
   void computeSizeAndOffsets();
 
+  /// \brief Compute the size and offset of all the DIEs in the given unit.
+  /// \returns The size of the root DIE.
+  unsigned computeSizeAndOffsetsForUnit(DwarfUnit *TheU);
+
   /// Define a unique number for the abbreviation.
   ///
   /// Compute the abbreviation for \c Die, look up its unique number, and
@@ -82,12 +89,15 @@ public:
   DIEAbbrev &assignAbbrevNumber(DIE &Die);
 
   /// \brief Add a unit to the list of CUs.
-  void addUnit(std::unique_ptr<DwarfUnit> U);
+  void addUnit(std::unique_ptr<DwarfCompileUnit> U);
 
   /// \brief Emit all of the units to the section listed with the given
   /// abbreviation section.
   void emitUnits(bool UseOffsets);
 
+  /// \brief Emit the given unit to its section.
+  void emitUnit(DwarfUnit *U, bool UseOffsets);
+
   /// \brief Emit a set of abbreviations to the specific section.
   void emitAbbrevs(MCSection *);
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index d75fea5d8c8..d2cf8effdc2 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -63,21 +63,19 @@ bool DIEDwarfExpression::isFrameRegister(unsigned MachineReg) {
   return MachineReg == TRI.getFrameRegister(*AP.MF);
 }
 
-DwarfUnit::DwarfUnit(unsigned UID, dwarf::Tag UnitTag,
-                     const DICompileUnit *Node, AsmPrinter *A, DwarfDebug *DW,
-                     DwarfFile *DWU)
-    : UniqueID(UID), CUNode(Node),
-      UnitDie(*DIE::get(DIEValueAllocator, UnitTag)), DebugInfoOffset(0),
-      Asm(A), DD(DW), DU(DWU), IndexTyDie(nullptr), Section(nullptr) {
+DwarfUnit::DwarfUnit(dwarf::Tag UnitTag, const DICompileUnit *Node,
+                     AsmPrinter *A, DwarfDebug *DW, DwarfFile *DWU)
+    : CUNode(Node), UnitDie(*DIE::get(DIEValueAllocator, UnitTag)), Asm(A),
+      DD(DW), DU(DWU), IndexTyDie(nullptr), Section(nullptr) {
   assert(UnitTag == dwarf::DW_TAG_compile_unit ||
          UnitTag == dwarf::DW_TAG_type_unit);
 }
 
-DwarfTypeUnit::DwarfTypeUnit(unsigned UID, DwarfCompileUnit &CU, AsmPrinter *A,
+DwarfTypeUnit::DwarfTypeUnit(DwarfCompileUnit &CU, AsmPrinter *A,
                              DwarfDebug *DW, DwarfFile *DWU,
                              MCDwarfDwoLineTable *SplitLineTable)
-    : DwarfUnit(UID, dwarf::DW_TAG_type_unit, CU.getCUNode(), A, DW, DWU),
-      CU(CU), SplitLineTable(SplitLineTable) {
+    : DwarfUnit(dwarf::DW_TAG_type_unit, CU.getCUNode(), A, DW, DWU), CU(CU),
+      SplitLineTable(SplitLineTable) {
   if (SplitLineTable)
     addSectionOffset(UnitDie, dwarf::DW_AT_stmt_list, 0);
 }
@@ -268,7 +266,7 @@ void DwarfUnit::addDIEEntry(DIE &Die, dwarf::Attribute Attribute, DIE &Entry) {
   addDIEEntry(Die, Attribute, DIEEntry(Entry));
 }
 
-void DwarfUnit::addDIETypeSignature(DIE &Die, const DwarfTypeUnit &Type) {
+void DwarfUnit::addDIETypeSignature(DIE &Die, uint64_t Signature) {
   // Flag the type unit reference as a declaration so that if it contains
   // members (implicit special members, static data member definitions, member
   // declarations for definitions in this CU, etc) consumers don't get confused
@@ -276,7 +274,7 @@ void DwarfUnit::addDIETypeSignature(DIE &Die, const DwarfTypeUnit &Type) {
   addFlag(Die, dwarf::DW_AT_declaration);
 
   Die.addValue(DIEValueAllocator, dwarf::DW_AT_signature,
-               dwarf::DW_FORM_ref_sig8, DIETypeSignature(Type));
+               dwarf::DW_FORM_ref_sig8, DIEInteger(Signature));
 }
 
 void DwarfUnit::addDIETypeSignature(DIE &Die, dwarf::Attribute Attribute,
@@ -1524,8 +1522,11 @@ void DwarfUnit::emitHeader(bool UseOffsets) {
   // start of the section. Use a relocatable offset where needed to ensure
   // linking doesn't invalidate that offset.
   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
-  Asm->emitDwarfSymbolReference(TLOF.getDwarfAbbrevSection()->getBeginSymbol(),
-                                UseOffsets);
+  if (UseOffsets)
+    Asm->EmitInt32(0);
+  else
+    Asm->emitDwarfSymbolReference(
+        TLOF.getDwarfAbbrevSection()->getBeginSymbol(), false);
 
   Asm->OutStreamer->AddComment("Address Size (in bytes)");
   Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index 82760bf2183..a79add630b3 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -67,9 +67,6 @@ public:
 /// source file.
 class DwarfUnit {
 protected:
-  /// A numeric ID unique among all CUs in the module
-  unsigned UniqueID;
-
   /// MDNode for the compile unit.
   const DICompileUnit *CUNode;
 
@@ -79,9 +76,6 @@ protected:
   /// Unit debug information entry.
   DIE &UnitDie;
 
-  /// Offset of the UnitDie from beginning of debug info section.
-  unsigned DebugInfoOffset;
-
   /// Target of Dwarf emission.
   AsmPrinter *Asm;
 
@@ -110,8 +104,8 @@ protected:
   /// The section this unit will be emitted in.
   MCSection *Section;
 
-  DwarfUnit(unsigned UID, dwarf::Tag, const DICompileUnit *CU, AsmPrinter *A,
-            DwarfDebug *DW, DwarfFile *DWU);
+  DwarfUnit(dwarf::Tag, const DICompileUnit *CU, AsmPrinter *A, DwarfDebug *DW,
+            DwarfFile *DWU);
 
   bool applySubprogramDefinitionAttributes(const DISubprogram *SP, DIE &SPDie);
 
@@ -127,14 +121,10 @@ public:
 
   // Accessors.
   AsmPrinter* getAsmPrinter() const { return Asm; }
-  unsigned getUniqueID() const { return UniqueID; }
   uint16_t getLanguage() const { return CUNode->getSourceLanguage(); }
   const DICompileUnit *getCUNode() const { return CUNode; }
   DIE &getUnitDie() { return UnitDie; }
 
-  unsigned getDebugInfoOffset() const { return DebugInfoOffset; }
-  void setDebugInfoOffset(unsigned DbgInfoOff) { DebugInfoOffset = DbgInfoOff; }
-
   /// Return true if this compile unit has something to write out.
   bool hasContent() const { return UnitDie.hasChildren(); }
 
@@ -221,7 +211,7 @@ public:
   void addDIEEntry(DIE &Die, dwarf::Attribute Attribute, DIEEntry Entry);
 
   /// Add a type's DW_AT_signature and set the  declaration flag.
-  void addDIETypeSignature(DIE &Die, const DwarfTypeUnit &Type);
+  void addDIETypeSignature(DIE &Die, uint64_t Signature);
   /// Add an attribute containing the type signature for a unique identifier.
   void addDIETypeSignature(DIE &Die, dwarf::Attribute Attribute,
                            StringRef Identifier);
@@ -383,12 +373,10 @@ class DwarfTypeUnit : public DwarfUnit {
   bool isDwoUnit() const override;
 
 public:
-  DwarfTypeUnit(unsigned UID, DwarfCompileUnit &CU, AsmPrinter *A,
-                DwarfDebug *DW, DwarfFile *DWU,
-                MCDwarfDwoLineTable *SplitLineTable = nullptr);
+  DwarfTypeUnit(DwarfCompileUnit &CU, AsmPrinter *A, DwarfDebug *DW,
+                DwarfFile *DWU, MCDwarfDwoLineTable *SplitLineTable = nullptr);
 
   void setTypeSignature(uint64_t Signature) { TypeSignature = Signature; }
-  uint64_t getTypeSignature() const { return TypeSignature; }
   void setType(const DIE *Ty) { this->Ty = Ty; }
 
   /// Emit the header for this unit, not including the initial length field.