The next step is to have some flavour of nextpnr succeed with my netlist.
Tried nextpnr-xilinx -> crash
```
  terminate called after throwing an instance of 'std::out_of_range'
    what():  vector::_M_range_check: __n (which is 1) >= this->size() (which is 1)
```
Tried nextpnr-himbaechel -> issue at mapping the DSPs
Issue opened https://github.com/YosysHQ/nextpnr/issues/1361