Re: The Emacs master is much slower than the emacs-27 branch.

[Eli Zaretskii]

> Date: Sat, 05 Dec 2020 08:44:38 +0000
> From: Gregory Heytings <ghe@sdf.org>
> cc: acm@muc.de, stephen.berman@gmx.net, emacs-devel@gnu.org
> 
> > I don't know what happens on your computer (what is your 
> > platform/compiler?) but on mine (Debian GNU/Linux with the latest Linux 
> > kernel and the latest GCC) the effect on -O0 is almost the same as on 
> > -Og for this particular benchmark.  I just tried again on the emacs-27 
> > branch:
> >
> > -Og: ~67s
> > -O0: ~63s
> > -O1: ~26s
> > -O2: ~18s
> > -O3: ~17s
> >
> 
> I'm sure you'll ask, so to avoid another round: yes, with make bootstrap, 
> on a fresh clone.  And I used CLFAGS='-Og -g3', CLFAGS='-O0 -g3', 
> CLFAGS='-O1 -g3', CLFAGS='-O2 -g3' and CLFAGS='-O3 -g3'.  If you need 
> other timings, feel free to ask.

I wasn't going to ask that, but I would like to point out one more
potential difference: I didn't compare two builds of master before and
after that commit.  Instead, I timed 32-bit builds of the current
emacs-27 and master branches which were both built with the following
optional switches to configure:

  --with-wide-int --with-modules --enable-checking=yes,glyphs 'CFLAGS=-O0 
-gdwarf-4 -g3'

Again, I don't expect any of this to matter so dramatically, so this
is just for completeness' sake.