[ObjectYAML] [COFF] Support multiple symbols with the same name

Differential Revision: https://reviews.llvm.org/D56294

llvm-svn: 350566
diff --git a/llvm/lib/ObjectYAML/COFFYAML.cpp b/llvm/lib/ObjectYAML/COFFYAML.cpp
index 9351ef9..fdd94f4 100644
--- a/llvm/lib/ObjectYAML/COFFYAML.cpp
+++ b/llvm/lib/ObjectYAML/COFFYAML.cpp
@@ -407,7 +407,8 @@
 void MappingTraits<COFFYAML::Relocation>::mapping(IO &IO,
                                                   COFFYAML::Relocation &Rel) {
   IO.mapRequired("VirtualAddress", Rel.VirtualAddress);
-  IO.mapRequired("SymbolName", Rel.SymbolName);
+  IO.mapOptional("SymbolName", Rel.SymbolName, StringRef());
+  IO.mapOptional("SymbolTableIndex", Rel.SymbolTableIndex);
 
   COFF::header &H = *static_cast<COFF::header *>(IO.getContext());
   if (H.Machine == COFF::IMAGE_FILE_MACHINE_I386) {