From: "Óscar Fuentes" <ofv@wanadoo.es>
To: emacs-devel@gnu.org
Subject: Re: Default compiler optimization level for building dev sources
Date: Fri, 22 Apr 2016 17:00:38 +0200 [thread overview]
Message-ID: <87h9etvgbt.fsf@wanadoo.es> (raw)
In-Reply-To: 8360v9671f.fsf@gnu.org
Eli Zaretskii <eliz@gnu.org> writes:
>> I'm using Emacs 25.0.92 on Windows and it seems remarkably slower than
>> the previous binary. This one was built with a plain config && make
>> while the previous one had CFLAGS set to -O3 and other extra
>> optimization flags.
>
> So you are saying that -O2 (that's the default) is significantly
> slower than -O3?
No, I'm saying that this binary feels quite slower than the previous
one.
> That's strange, my experience is that -O3 is
> generally not faster than -O2 and sometimes slower.
No arguing here. The cause must be elsewhere. The previous binary was
one year old and the current one is from a few days old master but I
doubt that such performance deterioration was caused by the introduced
changes with nobody noticing until now.
I need to investigate further.
>> Maybe the build does not turn on optimizations when it detects that the
>> sources are on a repo. Sorry for asking here instead of checking it
>> myself but today I have no access to the sources nor the web.
>
> I don't think so. The default is -O2, so if you want -O3, you need to
> request it by saying "CFLAGS='-O3' ./configure ...".
>
> Do you still have the source directory tree where you b uilt the
> previous binary? If so, please tell what configure-time switches you
> used and which compiler switches do you see in src/Makefile.
I *think* that the build dir is still around, but I have no access to
that VM for now. I trust you on the default CFLAGS, but maybe
makepkg-mingw (this is the MSYS2 way of building packages) did something
on its own. I'll check the Makefile and re-launch the build with some
flag for showing the compile command instead of just `CC foo.c' (I guess
that `make VERBOSE=1' will do.)
Thank you.
next prev parent reply other threads:[~2016-04-22 15:00 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-22 14:17 Default compiler optimization level for building dev sources Óscar Fuentes
2016-04-22 14:40 ` Eli Zaretskii
2016-04-22 15:00 ` Óscar Fuentes [this message]
2016-04-22 17:56 ` John Wiegley
2016-04-22 18:40 ` Eli Zaretskii
2016-04-22 18:53 ` Andreas Schwab
2016-04-22 20:18 ` Óscar Fuentes
2016-04-22 20:25 ` John Mastro
2016-04-22 20:41 ` Eli Zaretskii
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