I'm enormously frustrated that Google has been killing off advanced-search tools.
The loss of '+' is annoying, particularly since quoted and non-quoted mixtures are unreliable. Searching on "freebsd" "meltdown" might have solved your problem, but it's too unpredictable to be sure. My experience suggests that Google is doing something with site-level search, such that a site with only 'freebsd' won't appear but a site with 'freebsd' and 'meltdown' on different pages still might.
'-', meanwhile, seems to simply be disabled some of the time.
I'm primarily a DDG user, and I get annoyed that it often drops terms from my query as well. However, if you prefix the term with a +, such as `+freebsd +meltdown`, it will reliably keep that term in my query and show me what I want. So my queries often get overwritten, but at least I can reliably override it.
Lately I've also been noticing that the behaviour of some google search operators are broken. " something " "otherthing" is not considered as an AND " something " OR "otherthing" is not considered as an OR. Google shows me the results it wants. I recently tried to research FreeBSD and Meltdown (I tried many times: "FreeBSD" "Meltdown", "FreeBSD" AND "Meltdown" etc.) and almost no result involved the terms both FreeBSD and Meltdown. The interesting thing was, Google did not say there was no results matching my criteria, it kept showing me popular IT news, linux news etc. It was extremely frustrating.
The only operators that work are site, date and filetype. The logical operators do not work reliably or do not work at all.
If you're searching for something popular google finds it best, but if your search patterns are deviant google ignores you and even thinks you're a bot and refuses to service you.