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Re: [avr-gcc-list] More on optimization

From: Joerg Wunsch
Subject: Re: [avr-gcc-list] More on optimization
Date: Thu, 17 Oct 2002 13:14:43 +0200 (MET DST)

"Tvrtko A. Ursulin" <address@hidden> wrote:

> Nothing about -09 which I found was used in some Makefiles floating
> around the net ?

You can even write -O999 and it won't become more than -O3. ;-) Some
people blindly believe by just writing something there, they'll indeed
get better code as long as the compiler doesn't complain about it...
Even -O3 can already become a pessimization (it tries to inline very
much), and the frequently found -mcpu=pentiumoftheday switches were
often happy if they would optimize at least 1 % better (in terms of
overall execution speed)...

In terms of code size, i found that AVRs are usually best with just
-O1 (perhaps plus some micro-optimization in -f or -m options).  Even
-Os is usually already larger.

J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/
avr-gcc-list at http://avr1.org

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