1 files changed, 24 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 6fd0032f84c..ae95dd8ed66 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -2374,6 +2374,30 @@ llvm::DICompositeType *CGDebugInfo::CreateLimitedType(const RecordType *Ty) {
       getTagForRecord(RD), RDName, RDContext, DefUnit, Line, 0, Size, Align, 0,
       FullName);
 
+  // Elements of composite types usually have back to the type, creating
+  // uniquing cycles.  Distinct nodes are more efficient.
+  switch (RealDecl->getTag()) {
+  default:
+    llvm_unreachable("invalid composite type tag");
+
+  case llvm::dwarf::DW_TAG_array_type:
+  case llvm::dwarf::DW_TAG_enumeration_type:
+    // Array elements and most enumeration elements don't have back references,
+    // so they don't tend to be involved in uniquing cycles and there is some
+    // chance of merging them when linking together two modules.  Only make
+    // them distinct if they are ODR-uniqued.
+    if (FullName.empty())
+      break;
+
+  case llvm::dwarf::DW_TAG_structure_type:
+  case llvm::dwarf::DW_TAG_union_type:
+  case llvm::dwarf::DW_TAG_class_type:
+    // Immediatley resolve to a distinct node.
+    RealDecl =
+        llvm::MDNode::replaceWithDistinct(llvm::TempDICompositeType(RealDecl));
+    break;
+  }
+
   RegionMap[Ty->getDecl()].reset(RealDecl);
   TypeCache[QualType(Ty, 0).getAsOpaquePtr()].reset(RealDecl);