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| Date: | Tue, 11 May 1999 00:41:13 +0200 |
| To: | David Whysong <dwhysong AT physics DOT ucsb DOT edu> |
| Cc: | Marc Lehmann <pcg AT goof DOT com>, pgcc AT delorie DOT com |
| Subject: | Re: Optimization question |
| Message-ID: | <19990511004113.N22062@cerebro.laendle> |
| Mail-Followup-To: | David Whysong <dwhysong AT physics DOT ucsb DOT edu>, |
| Marc Lehmann <pcg AT goof DOT com>, pgcc AT delorie DOT com | |
| References: | <19990510201927 DOT E10032 AT cerebro DOT laendle> <Pine DOT LNX DOT 4 DOT 04 DOT 9905101436230 DOT 15547-100000 AT sal DOT physics DOT ucsb DOT edu> |
| Mime-Version: | 1.0 |
| In-Reply-To: | <Pine.LNX.4.04.9905101436230.15547-100000@sal.physics.ucsb.edu>; from David Whysong on Mon, May 10, 1999 at 03:34:44PM -0700 |
| X-Operating-System: | Linux version 2.2.7 (root AT cerebro) (gcc driver version pgcc-2.93.09 19990221 (gcc2 ss-980929 experimental) executing gcc version 2.7.2.3) |
| From: | Marc Lehmann <pcg AT goof DOT com> |
| Reply-To: | pgcc AT delorie DOT com |
| X-Mailing-List: | pgcc AT delorie DOT com |
| X-Unsubscribes-To: | listserv AT delorie DOT com |
On Mon, May 10, 1999 at 03:34:44PM -0700, David Whysong wrote:
> Theory doesn't seem to fit the data very well then. :-) I have gained
> nearly a factor of two in speed after doing some CSE by hand. Even on the
> simple code fragment I posted, a little "hand optimizing" significantly
> reduced the number of fmul ops. As far as I can see, very little or no CSE
> was being done at all.
Have you benchmarked it? fmuls are not really slower than fadds, for
example. However, if you can manage to get a (sensibly sized ;) example
of where cse fails I'd be happy to look into it!
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