Re: Native compilation on as default?

[Eli Zaretskii]

> From: brickviking <brickviking@gmail.com>
> Date: Thu, 26 Oct 2023 16:55:08 +1300
> 
> To add to what RMS has stated, I'm on an older machine with not a lot of room 
> left on the primary
> partition. I understand that's on me, but I wanted to add my notes about my 
> local experience.
> 
> I compiled Emacs as a test with AOT turned on, and found that it started 
> creating *.eln files. Lots of
> them. I recompile Emacs on a fairly regular basis, and after one 
> compile/install of Emacs, I noted at
> least an extra 40Mb after about an hour's running with erc, org-mode and 
> ef-themes (amongst
> others). On my older 2008-era machine that's starting to really show its age, 
> the extra .eln files were
> not really worth it for me. I wish I had better news, I've been wanting a 
> sped-up emacs for a little while
> now. To be fair, I _thought_ I saw a speed increase in what amounts to 
> display code, but I'm not a
> programmer, mainly a user.

As with any optional Emacs feature, even those which are ON by
default, disabling them is easy if for some reason you don't want it.
In this case, in addition to --without-native-compilation, you can
simply make sure libgccjit is not available on your system, and then
native compilation will be disabled in your build.

So I see no problems here that would unnecessarily inconvenience users
of old/slow systems.

> Is there a facility to purge out-of-date versions of the .eln files for a 
> version that is installed later, and
> is that facility easy enough to look for via C-h f? This might make native 
> compilation easier to
> swallow.

See the command native-compile-prune-cache, which is new in Emacs 29.

For *.eln files that are installed under /usr/local, you will need to
uninstall the old Emacs version or manually delete its versioned
subdirectories.