From mboxrd@z Thu Jan  1 00:00:00 1970
From: Zack Weinberg <zack@codesourcery.com>
To: Brad Lucier <lucier@math.purdue.edu>
Cc: gcc@gcc.gnu.org, Jan Hubicka <jh@suse.cz>
Subject: Re: Some statement counts for gcc
Date: Mon, 26 Aug 2002 00:17:00 -0000
Message-id: <20020826071657.GD28065@codesourcery.com>
References: <200208252304.g7PN4Bc18560@banach.math.purdue.edu>
X-SW-Source: 2002-08/msg01573.html

On Sun, Aug 25, 2002 at 06:04:11PM -0500, Brad Lucier wrote:

>  branch prediction     : 165.11 (33%) usr   0.07 ( 1%) sys 165.50 (33%) wall
...
> A surprising (to me) number of lines in real.c are executed; I might look
> there to see what's going on.

The branch predictor uses emulated floating point numbers internally.
Jan Hubicka has explained why this is currently necessary -- can't
find the message at the moment though.  However, real.c is indeed
quite slow; I suspect that accounts entirely for the amount of time
spent in this patch

If I remember correctly this code has a very complicated flow graph,
and branch prediction may not help much; perhaps the right thing is
to detect code like this and disable that optimization.

zw