How to preserve net names in DC while synthesis

There's no easy way if you want the best optimization. The signals connected to registers are usually preserved, but after that you're more or less at the mercy of the synthesis tool. If you absolutely need to get some signals preserved, I'm not sure dont_touch will help that much. Probably the best way is to bring internal signals to the top as output ports and ask DC not to optimize them away if they're not connected. I assume there must a flag for this somewhere, though I haven't really looked into it.

We've pretty much given up on even trying to get a nice match and have formal equivalence check validate the correctness of the netlist. Yes, this makes netlist hacking extremely painful: just try to make sure your RTL is correct. :-)

Tom