Mail Archives: djgpp/1997/01/17/00:51:29
From: | "John M. Aldrich" <fighteer AT cs DOT com>
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Newsgroups: | comp.os.msdos.djgpp
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Subject: | Re: Compile extensions
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Date: | Thu, 16 Jan 1997 19:05:04 -0800
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Organization: | Two pounds of chaos and a pinch of salt
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Lines: | 28
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Message-ID: | <32DEEC60.2F98@cs.com>
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References: | <01bc03eb$6be81120$492449c2 AT default>
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Reply-To: | fighteer AT cs DOT com
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NNTP-Posting-Host: | ppp106.cs.com
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Mime-Version: | 1.0
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To: | djgpp AT delorie DOT com
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DJ-Gateway: | from newsgroup comp.os.msdos.djgpp
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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.
--
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