DAG Debugging

Hi
   I am running into an issue with creation of an unexpected node. Can
some one tell me how one can find where the particular node is being
created? For instance, what might be a good point to break point and
looking for what ?
The dump of the nodes gets printed as unknown node.

thanks
shrey

The dump of the nodes gets printed as unknown node.

"Unknown" nodes are usually just target-specific ones.