digraph G {
yosys [label="yosys\narch=xilinx\noutput_format=edif"]
vpnr [label="vivado\nsynth=none"]
"$project.bit" [shape=box,style=filled]
"$project.v" [shape=box,style=filled]
frontends -> yosys[label="synth==yosys         "];
frontends -> "vivado"[label="synth!=yosys"];
yosys -> "vpnr";
vivado -> "$project.v"[label="pnr==none"];
vivado -> "$project.bit"[label="pnr!=none"];
"vpnr" -> "$project.bit";
}