Date: Mon, 10 May 1999 21:53:24 +0200
To: pgcc AT delorie DOT com
Subject: Re: Optimization question
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In-Reply-To: <Pine.LNX.4.04.9905100834040.13078-100000@sal.physics.ucsb.edu>; from David Whysong on Mon, May 10, 1999 at 09:09:25AM -0700
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From: Marc Lehmann <pcg AT goof DOT com>
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On Mon, May 10, 1999 at 09:09:25AM -0700, David Whysong wrote:
> On Mon, 10 May 1999, Dr H. T. Leung wrote:
> 
> >If you had read the mailing list archive, it is terribly unfair to people
> >on the list to cc you replies when you are not on the list. If you want to
> >ask a question, subscribe, read on for a while, then post (then maybe
> >unsubscribe). 
> 
> That's EXTREMELY strange. Anyway I'm now subscribed to the list. Sorry...

It would be strange, yes ;) Hello, btw!

> Thanks, this is exactly what I wanted to know. Optimizing comiplers like
> egcs/pgcc do "strength reduction", but I wasn't sure if this kind of

strength reduction is only for loops, however, when your code is in a
loop...

A problem with strentgh reduction, however, is that it creates a lot
more registers, which the x86 doens't have, so strentgh reduction might
atcually hurt (though you need it for loop unrolling).

> construct would be taken care of by the compiler, or if I need to do it by
> hand.

It should be automatic, but this is a very extreme case, so this might be
worthwhile!

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