Subject: Re: bug#66750: Unhelpful text in C-h v for variables with a lambda form as value

From: Alan Mackenzie <[email-masked]>
Date: Sat, 28 Oct 2023 15:59:26 +0000

Hello, Stefan.

On Sat, Oct 28, 2023 at 08:04:00 -0700, Stefan Kangas wrote:
> Alan Mackenzie <[email-masked]> writes:

> > Currently feature/named-lambdas is mostly working, not fully working.
> > Probably the most pressing of these deficiencies is that native compiled
> > lambda functions don't yet get their defining symbol set.

As I've said, this is now fixed.

> > There have been substantial amendments compared with the master branch,
> > and it has not been tested much by anybody but me.

> > Assuming it can be brought to a fully working state, there would be an
> > extra symbol in each function definition which would make Emacs
> > marginally bigger.

> Does it have any performance implications?

Yes, but very little.

If I scroll through xdisp.c, displaying all the time, in C Mode:
(i) master:                  18.850s, 18.767s, 18.747s.
(ii) feature/named-lambdas:  18.630s, 18.738s, 18.782s.

If I likewise scroll through osprey_reg_map_macro.h (a 4 MB .h file
specifying some hardware registers), in c-ts-mode:
(i) master:                  10.157s, 10.203s, 10.169s
(ii) feature/named-lambdas:  10.207s, 10.219s, 10.257s

..  Not a very scientific timing, not done from emacs -Q, but a fair
test.  It would seem any slowdown is less than 1%.

-- 
Alan Mackenzie (Nuremberg, Germany).