Yes, my impression is that many production-grade compiler dev teams have technique like this, though often they do not talk much about it, often they are propri

Yes, my impression is that many production-grade compiler dev teams have technique like this, though often they do not talk much about it, often they are proprietary and/or covered by NDAs, and often they are, as you say, 'selected' code bases. I'm very curious for other compiler teams to say more about what they do here.