From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marc Lehmann <pcg@goof.com>
To: egcs@cygnus.com
Subject: Re: Optimizations
Date: Mon, 15 Dec 1997 05:38:00 -0000
Message-id: <19971215135439.50575@cerebro.laendle>
References: <199712142230.RAA10693@tweedledumb.cygnus.com>
X-SW-Source: 1997-12/msg00833.html

On Sun, Dec 14, 1997 at 05:30:48PM -0500, meissner@cygnus.com wrote:
> | Marc Lehmann wrote:
> | > -fschedule-insns is a *loss* on x86 cpu's!
> | 
> | care to explain why it is a loss (and most probably also -fschedule-insns2)
> 
> The problem is that -fschedule-insns, -funroll-{,all-}loops, and
> -fstrength-reduce all tend to work by creating more registers to hold

The really intersting point is that -fschedule-insns ins generally a loss
on x86, while -funroll-all-loops is generally a win! (even more
so that -funroll-loops)

I guess loop unrolling should be more clever, i.e. while it should
unroll loops without constant number ofm iterations, it should'nt
unroll all of them.

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      ---==---(_)__  __ ____  __       Marc Lehmann       +--
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    The choice of a GNU generation                        |
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