It was an old joke that the opposite of "goto" is "come from", or that if goto is considered harmful, nobody said anything about a "come from". Marking something as a branch target reminds me of this.
COMEFROM considered harm-mitigating
It ingeniously makes Return Oriented Programming (ROP) a lot harder.
You know, that’d be a fantastic OpenBSD release name.
Here’s hoping a dev sees this comment; there’s already been a few commenting in this thread.