Explain why this is here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63342 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/DAGISelEmitter.cpp b/utils/TableGen/DAGISelEmitter.cpp
index ace15e5..773b06a 100644
--- a/utils/TableGen/DAGISelEmitter.cpp
+++ b/utils/TableGen/DAGISelEmitter.cpp
@@ -1060,6 +1060,7 @@
       std::string Code = "Opc" + utostr(OpcNo);
 
       if (!isRoot || (InputHasChain && !NodeHasChain))
+        // For call to "getTargetNode()".
         Code += ", N.getDebugLoc()";
 
       emitOpcode(II.Namespace + "::" + II.TheDef->getName());