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

[Eli Zaretskii]

> From: Óscar Fuentes <ofv@wanadoo.es>
> Date: Fri, 04 Dec 2020 17:28:36 +0100
> 
> Stephen Berman <stephen.berman@gmx.net> writes:
> 
> > emacs-27:
> >
> > system-configuration-options
> > "'CFLAGS=-Og -g3' PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig"
> >
> > system-configuration-features
> > "XPM JPEG TIFF GIF PNG RSVG SOUND DBUS GSETTINGS GLIB NOTIFY INOTIFY ACL
> > GNUTLS LIBXML2 FREETYPE HARFBUZZ XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11
> > XDBE XIM MODULES THREADS LIBSYSTEMD PDUMPER LCMS2 GMP"
> >
> > master:
> >
> > system-configuration-options
> > "--with-xwidgets 'CFLAGS=-Og -g3' PKG_CONFIG_PATH=/opt/qt5/lib/pkgconfig"
> >
> > system-configuration-features
> > "XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND DBUS GSETTINGS GLIB NOTIFY
> > INOTIFY ACL GNUTLS LIBXML2 FREETYPE HARFBUZZ ZLIB TOOLKIT_SCROLL_BARS
> > GTK3 X11 XDBE XIM MODULES THREADS XWIDGETS LIBSYSTEMD PDUMPER LCMS2"
> 
> Please correct me if I'm wrong, but overriding CFLAGS means that gcc
> compiles with default optimization level, wich is -O0, hence you are
> comparing unoptimized builds, right?

No, because CFLAGS say -Og in both cases, which means the compiler
uses optimization level slightly lower than -O1.

> In that case, a tiny change on some often-used macro or function can
> make a big difference.

But I see no significant difference in my unoptimized builds of both
branches.