From: "John M. Aldrich" <fighteer AT cs DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Compile extensions
Date: Thu, 16 Jan 1997 19:05:04 -0800
Organization: Two pounds of chaos and a pinch of salt
Lines: 28
Message-ID: <32DEEC60.2F98@cs.com>
References: <01bc03eb$6be81120$492449c2 AT default>
Reply-To: fighteer AT cs DOT com
NNTP-Posting-Host: ppp106.cs.com
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Thomas Harte wrote:
> 
>         Which extensions to the regular GCC command line do you all recommend to
> use when compiling for speed over size. My programs use a lot of fixed
> point maths, and some occasional floating point, and use both the Allegro
> and SB_LIB libraries.

Look into the gcc docs for Optimization Flags.  In general, you want to
use one of -O, -O2, or -O3, with each level attempting to achieve a
higher speed-size tradeoff.  Generally, -O2 is the best overall choice,
giving you maximum speed for very little increase in size, and sometimes
even a decrease!  -O3 goes all out, inlining as much code as it can. 
This significantly bloats your program's size, but doesn't always
improve speed to compensate.

You can also specify various -f switches to directly control what
optimizations are and aren't used.

A word of advice:  Definitely read all of chapter 14 of the FAQ; it
contains some excellent tips on speed and optimization.

-- 
---------------------------------------------------------------------
| John M. Aldrich, aka Fighteer I      |   mailto:fighteer AT cs DOT com   |
| God's final message to His Creation: | http://www.cs.com/fighteer |
| "We apologize for the inconvenience."| Fight against proprietary  |
|                      - Douglas Adams | software - support the FSF!|
---------------------------------------------------------------------