How are regexen implemented in Emacs?

[Marcin Borkowski]

Hi all,

some time ago I read (well, skimmed) this article:
https://swtch.com/~rsc/regexp/regexp1.html

I looked at
https://www.gnu.org/software/emacs/manual/html_node/elisp/Regexp-Problems.html
and started to wonder if the hints there mean that Emacs has a "naive",
backtracking regex engine or a FA-based one?

Before I get yelled at, let me make it clear: I'm not accusing Emacs
devs of sloppy programming.  In fact, my confusion might result from me
not understanding something.  But the warnings in the manual about some
regexen being slow worry me a tiny little bit.

Best,

-- 
Marcin Borkowski
http://mbork.pl