3 files changed, 15 insertions, 1 deletions
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
index 0bfa1d46008..78ccad48141 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
@@ -47,6 +47,9 @@ void DwarfFile::emitUnit(DwarfUnit *TheU, bool UseOffsets) {
   Asm->OutStreamer->SwitchSection(S);
   TheU->emitHeader(UseOffsets);
   Asm->emitDwarfDIE(TheU->getUnitDie());
+
+  if (MCSymbol *EndLabel = TheU->getEndLabel())
+    Asm->OutStreamer->EmitLabel(EndLabel);
 }
 
 // Compute the size and offset for each DIE.
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 062eb3a8892..991dac7cf35 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -1553,7 +1553,14 @@ DIE *DwarfUnit::getOrCreateStaticMemberDIE(const DIDerivedType *DT) {
 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());
+  if (!DD->useSectionsAsReferences()) {
+    StringRef Prefix = isDwoUnit() ? "debug_info_dwo_" : "debug_info_";
+    MCSymbol *BeginLabel = Asm->createTempSymbol(Prefix + "start");
+    EndLabel = Asm->createTempSymbol(Prefix + "end");
+    Asm->EmitLabelDifference(EndLabel, BeginLabel, 4);
+    Asm->OutStreamer->EmitLabel(BeginLabel);
+  } else
+    Asm->emitInt32(getHeaderSize() + getUnitDie().getSize());
 
   Asm->OutStreamer->AddComment("DWARF version number");
   unsigned Version = DD->getDwarfVersion();
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index c5cb7e1bc33..a59ebb7c146 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -49,6 +49,9 @@ protected:
   /// Target of Dwarf emission.
   AsmPrinter *Asm;
 
+  /// Emitted at the end of the CU and used to compute the CU Length field.
+  MCSymbol *EndLabel = nullptr;
+
   // Holders for some common dwarf information.
   DwarfDebug *DD;
   DwarfFile *DU;
@@ -82,6 +85,7 @@ protected:
 public:
   // Accessors.
   AsmPrinter* getAsmPrinter() const { return Asm; }
+  MCSymbol *getEndLabel() const { return EndLabel; }
   uint16_t getLanguage() const { return CUNode->getSourceLanguage(); }
   const DICompileUnit *getCUNode() const { return CUNode; }