Re: [PATCH] add compiled regexp primitive lisp object

[Stefan Monnier]

>>> 1. They could be inspected from Elisp, and hopefully optimized
>>>    better. For now, there is simply no way to detect which parts of
>>>    regexps are slow and which are not.
>> You can now/already use `re--describe-compiled` to inspect the compiled
>> regexps used by Emacs's regexp engine.
> But only when Emacs is compiled with --enable-checking. Also, no
> documentation about the output is available. So, in its current form,
> `re--describe-compiled' is only usable for debugging Emacs itself. Not
> on Elisp-hacker level.
> `re--describe-compiled' can certainly be improved.

It's definitely crude, yes.
Mattias also had an ELisp package that did a better job and should now
work even without `--enable-checking`: https://github.com/mattiase/regexp-disasm


        Stefan