delorie.com/archives/browse.cgi   search  
Mail Archives: djgpp/1999/12/09/09:40:26

Date: Thu, 9 Dec 1999 16:05:46 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender: eliz AT is
To: George Ryot <ryot AT bigfoot DOT com>
cc: djgpp AT delorie DOT com
Subject: Re: fftw give nonsense with float ok with double
In-Reply-To: <384e8f71.5388976@news.clara.net>
Message-ID: <Pine.SUN.3.91.991209160327.22560E-100000@is>
MIME-Version: 1.0
Reply-To: djgpp AT delorie DOT com
X-Mailing-List: djgpp AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com

On Wed, 8 Dec 1999, George Ryot wrote:

> Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> wrote:
> 
> >  2. Why do you use -O3?  If you don't have any special reason, try -O2
> >     instead, it usually yields better results anyway.
> 
> I am wondering in what way does -O2 yield better results than -O3, are
> you refering to code size or is there another consideration?

No, I meant speed.  In many cases, -O2 yields a faster program, the usual 
cause being code cache overflow.

In addition, -O2 is much better tested, since it is the usual 
optimization level, so many programs, including the compiler itself, are 
compiled with it.  Therefore, bugs are less probable to happen with -O2.

- Raw text -


  webmaster     delorie software   privacy  
  Copyright 2019   by DJ Delorie     Updated Jul 2019