the patch attatched adds the option -view-dag-color-node=<list> to llc. The list of strings is matched with the names of the labels of nodes when displaying a graph, so that matching nodes are displayed in a colored bold style. I find this extremely usful on selectionDAGs to spot specific nodes in larger graphs.
You may complain that the implementation should be interacting more with the DOTGraphTraits class, but OTOH this might be an interesting feature for any type of graph, and as such it is certainly the lightest implementation.
Anyway, if this is considered an interesting feature for the mainline but unacceptable this way please let me know, I might eventually change it according to your suggestions.
GraphWriter_color.patch (2.18 KB)