Add some helpful comments on DIEValue types that we expect to hash.

llvm-svn: 203055
diff --git a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
index bc8c695..ea0c1cf 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
@@ -346,12 +346,15 @@
       hashBlockData(cast<DIELoc>(Value)->getValues());
     }
     break;
+    // FIXME: Handle loclistptr.
+  case DIEValue::isLocList:
+    // FIXME: It's uncertain whether or not we should handle this at the moment.
   case DIEValue::isExpr:
   case DIEValue::isLabel:
   case DIEValue::isDelta:
+    // These two were handled above.
   case DIEValue::isEntry:
   case DIEValue::isTypeSignature:
-  case DIEValue::isLocList:
     llvm_unreachable("Add support for additional value types.");
   }
 }