Thx @User saw the HA and FA - yes, my experience show that it depends on constraints, loading and HDL/circuit whethrr its used. I just dont know if yosys supports + and * like Genus and DC. As I said before, within many of my high speed designs I typically see gates other than FA and HA cells. Again it varies but yes SKY130 cells have HA and FA in them. We hope to add a FA and HA cell to OSUs library soon.