1 files changed, 11 insertions, 17 deletions
diff --git a/lib/DebugInfo/CodeView/DebugSubsectionRecord.cpp b/lib/DebugInfo/CodeView/DebugSubsectionRecord.cpp
index cfd1c5d3ab0c..e9124e68fe82 100644
--- a/lib/DebugInfo/CodeView/DebugSubsectionRecord.cpp
+++ b/lib/DebugInfo/CodeView/DebugSubsectionRecord.cpp
@@ -34,14 +34,6 @@ Error DebugSubsectionRecord::initialize(BinaryStreamRef Stream,
 
   DebugSubsectionKind Kind =
       static_cast<DebugSubsectionKind>(uint32_t(Header->Kind));
-  switch (Kind) {
-  case DebugSubsectionKind::FileChecksums:
-  case DebugSubsectionKind::Lines:
-  case DebugSubsectionKind::InlineeLines:
-    break;
-  default:
-    llvm_unreachable("Unexpected debug fragment kind!");
-  }
   if (auto EC = Reader.readStreamRef(Info.Data, Header->Length))
     return EC;
   Info.Container = Container;
@@ -50,9 +42,7 @@ Error DebugSubsectionRecord::initialize(BinaryStreamRef Stream,
 }
 
 uint32_t DebugSubsectionRecord::getRecordLength() const {
-  uint32_t Result = sizeof(DebugSubsectionHeader) + Data.getLength();
-  assert(Result % alignOf(Container) == 0);
-  return Result;
+  return sizeof(DebugSubsectionHeader) + Data.getLength();
 }
 
 DebugSubsectionKind DebugSubsectionRecord::kind() const { return Kind; }
@@ -64,25 +54,29 @@ DebugSubsectionRecordBuilder::DebugSubsectionRecordBuilder(
     : Subsection(std::move(Subsection)), Container(Container) {}
 
 uint32_t DebugSubsectionRecordBuilder::calculateSerializedLength() {
-  uint32_t Size =
-      sizeof(DebugSubsectionHeader) +
-      alignTo(Subsection->calculateSerializedSize(), alignOf(Container));
+  // The length of the entire subsection is always padded to 4 bytes, regardless
+  // of the container kind.
+  uint32_t Size = sizeof(DebugSubsectionHeader) +
+                  alignTo(Subsection->calculateSerializedSize(), 4);
   return Size;
 }
 
-Error DebugSubsectionRecordBuilder::commit(BinaryStreamWriter &Writer) {
+Error DebugSubsectionRecordBuilder::commit(BinaryStreamWriter &Writer) const {
   assert(Writer.getOffset() % alignOf(Container) == 0 &&
          "Debug Subsection not properly aligned");
 
   DebugSubsectionHeader Header;
   Header.Kind = uint32_t(Subsection->kind());
-  Header.Length = calculateSerializedLength() - sizeof(DebugSubsectionHeader);
+  // The value written into the Header's Length field is only padded to the
+  // container's alignment
+  Header.Length =
+      alignTo(Subsection->calculateSerializedSize(), alignOf(Container));
 
   if (auto EC = Writer.writeObject(Header))
     return EC;
   if (auto EC = Subsection->commit(Writer))
     return EC;
-  if (auto EC = Writer.padToAlignment(alignOf(Container)))
+  if (auto EC = Writer.padToAlignment(4))
     return EC;
 
   return Error::success();