Re: Ahead of time compilation?

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 14 Sep 2018 18:16:36 -0400
> From: "Perry E. Metzger" <perry@piermont.com>
> 
> Given the recent JIT discussion, it occurs to me that a large
> fraction of the elisp infrastructure in the average emacs is the
> stuff that gets slurped in and undumped. Perhaps all that stuff could
> get ahead of time compiled before undump for performance? Build time
> isn't nearly as relevant for me as speed during execution, and on
> platforms that don't have the infra, the interpreter could continue
> to be use for that stuff.

IMO, before we decide to do this, we should convince ourselves that
JIT in the libjit branch indeed speeds up things significantly enough
for us to bother doing the above.  There was contradictory evidence
about that in the past, see recent threads on this list.  As one data
point I measured myself, the time it took to byte-compile all of the
Lisp files in the Emacs tree was almost exactly the same with and
without JIT.

Benchmarks of JIT performance as compared to byte-compiled code are
therefore greatly appreciated.  For the issue you raise above, I guess
we should try benchmarking code that gets dumped into the Emacs
executable, from preloaded packages; you can see them listed in
loadup.el.

Thanks.