Debug Info Testing: use null instead of an empty string in context field.

llvm-svn: 190284
diff --git a/llvm/test/CodeGen/Hexagon/hwloop-dbg.ll b/llvm/test/CodeGen/Hexagon/hwloop-dbg.ll
index 1c7f6a2..e5eb086 100644
--- a/llvm/test/CodeGen/Hexagon/hwloop-dbg.ll
+++ b/llvm/test/CodeGen/Hexagon/hwloop-dbg.ll
@@ -41,7 +41,7 @@
 !3 = metadata !{metadata !5}
 !5 = metadata !{i32 786478, metadata !28, null, metadata !"foo", metadata !"foo", metadata !"", i32 1, metadata !7, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 true, void (i32*, i32*)* @foo, null, null, metadata !11, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [foo]
 !6 = metadata !{i32 786473, metadata !28} ; [ DW_TAG_file_type ]
-!7 = metadata !{i32 786453, i32 0, metadata !"", i32 0, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !8, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{i32 786453, i32 0, null, i32 0, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !8, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
 !8 = metadata !{null, metadata !9, metadata !9}
 !9 = metadata !{i32 786447, null, null, metadata !"", i32 0, i64 32, i64 32, i64 0, i32 0, metadata !10} ; [ DW_TAG_pointer_type ] [line 0, size 32, align 32, offset 0] [from int]
 !10 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]