3 files changed, 30 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 66ac0e7271d..147f03e2c6d 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -690,7 +690,10 @@ void DwarfCompileUnit::emitHeader(bool UseOffsets) {
     Asm->OutStreamer->EmitLabel(LabelBegin);
   }
 
-  DwarfUnit::emitHeader(UseOffsets);
+  dwarf::UnitType UT = Skeleton ? dwarf::DW_UT_split_compile
+                                : DD->useSplitDwarf() ? dwarf::DW_UT_skeleton
+                                                      : dwarf::DW_UT_compile;
+  DwarfUnit::emitCommonHeader(UseOffsets, UT);
 }
 
 /// addGlobalName - Add a new global name to the compile unit.
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 0c57f8222ee..f74d7bf2cb1 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -1531,18 +1531,27 @@ DIE *DwarfUnit::getOrCreateStaticMemberDIE(const DIDerivedType *DT) {
   return &StaticMemberDIE;
 }
 
-void DwarfUnit::emitHeader(bool UseOffsets) {
+void DwarfUnit::emitCommonHeader(bool UseOffsets, dwarf::UnitType UT) {
   // Emit size of content not including length itself
   Asm->OutStreamer->AddComment("Length of Unit");
   Asm->EmitInt32(getHeaderSize() + getUnitDie().getSize());
 
   Asm->OutStreamer->AddComment("DWARF version number");
-  Asm->EmitInt16(DD->getDwarfVersion());
-  Asm->OutStreamer->AddComment("Offset Into Abbrev. Section");
+  unsigned Version = DD->getDwarfVersion();
+  Asm->EmitInt16(Version);
+
+  // DWARF v5 reorders the address size and adds a unit type.
+  if (Version >= 5) {
+    Asm->OutStreamer->AddComment("DWARF Unit Type");
+    Asm->EmitInt8(UT);
+    Asm->OutStreamer->AddComment("Address Size (in bytes)");
+    Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
+  }
 
   // We share one abbreviations table across all units so it's always at the
   // start of the section. Use a relocatable offset where needed to ensure
   // linking doesn't invalidate that offset.
+  Asm->OutStreamer->AddComment("Offset Into Abbrev. Section");
   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
   if (UseOffsets)
     Asm->EmitInt32(0);
@@ -1550,12 +1559,16 @@ void DwarfUnit::emitHeader(bool UseOffsets) {
     Asm->emitDwarfSymbolReference(
         TLOF.getDwarfAbbrevSection()->getBeginSymbol(), false);
 
-  Asm->OutStreamer->AddComment("Address Size (in bytes)");
-  Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
+  if (Version <= 4) {
+    Asm->OutStreamer->AddComment("Address Size (in bytes)");
+    Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
+  }
 }
 
 void DwarfTypeUnit::emitHeader(bool UseOffsets) {
-  DwarfUnit::emitHeader(UseOffsets);
+  DwarfUnit::emitCommonHeader(UseOffsets, 
+                              DD->useSplitDwarf() ? dwarf::DW_UT_split_type
+                                                  : dwarf::DW_UT_type);
   Asm->OutStreamer->AddComment("Type Signature");
   Asm->OutStreamer->EmitIntValue(TypeSignature, sizeof(TypeSignature));
   Asm->OutStreamer->AddComment("Type DIE Offset");
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index 89e654b33d0..a48b976a6fa 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -279,11 +279,13 @@ public:
   virtual unsigned getHeaderSize() const {
     return sizeof(int16_t) + // DWARF version number
            sizeof(int32_t) + // Offset Into Abbrev. Section
-           sizeof(int8_t);   // Pointer Size (in bytes)
+           sizeof(int8_t) +  // Pointer Size (in bytes)
+           (DD->getDwarfVersion() >= 5 ? sizeof(int8_t)
+                                       : 0); // DWARF v5 unit type
   }
 
   /// Emit the header for this unit, not including the initial length field.
-  virtual void emitHeader(bool UseOffsets);
+  virtual void emitHeader(bool UseOffsets) = 0;
 
   virtual DwarfCompileUnit &getCU() = 0;
 
@@ -308,6 +310,9 @@ protected:
   void updateAcceleratorTables(const DIScope *Context, const DIType *Ty,
                                const DIE &TyDIE);
 
+  /// Emit the common part of the header for this unit.
+  void emitCommonHeader(bool UseOffsets, dwarf::UnitType UT);
+
 private:
   void constructTypeDIE(DIE &Buffer, const DIBasicType *BTy);
   void constructTypeDIE(DIE &Buffer, const DIDerivedType *DTy);