[llvm-objdump] Add warning messages if disassembly + source for problematic inputs

Summary: Addresses https://bugs.llvm.org/show_bug.cgi?id=41905

Reviewers: jhenderson, rupprecht, grimar

Reviewed By: jhenderson, grimar

Subscribers: RKSimon, MaskRay, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62462

llvm-svn: 368963
diff --git a/llvm/tools/llvm-xray/func-id-helper.cpp b/llvm/tools/llvm-xray/func-id-helper.cpp
index dc821a4..afc912a 100644
--- a/llvm/tools/llvm-xray/func-id-helper.cpp
+++ b/llvm/tools/llvm-xray/func-id-helper.cpp
@@ -36,7 +36,7 @@
   ModuleAddress.SectionIndex = object::SectionedAddress::UndefSection;
   if (auto ResOrErr = Symbolizer.symbolizeCode(BinaryInstrMap, ModuleAddress)) {
     auto &DI = *ResOrErr;
-    if (DI.FunctionName == "<invalid>")
+    if (DI.FunctionName == DILineInfo::BadString)
       F << "@(" << std::hex << It->second << ")";
     else
       F << DI.FunctionName;