From: Marius Vollmer <mvo@zagadka.de>
Cc: guile-user@gnu.org
Subject: Re: Does anyone have a better scm_string_hash ?
Date: Mon, 17 Nov 2003 17:29:48 +0100 [thread overview]
Message-ID: <87n0avq7pf.fsf@zagadka.ping.de> (raw)
In-Reply-To: <87u153q8yk.fsf@zagadka.ping.de> (Marius Vollmer's message of "Mon, 17 Nov 2003 17:02:43 +0100")
Marius Vollmer <mvo@zagadka.de> writes:
> Just for kicks, I'm now going to see what kind of code GCC generates
> for h*37 as compared to (h<<5) + (h<<2) + h...
Interesting. For h = a + (h<<5) + (h<<2) + h we get this sequence
(one line is one machine instruction):
x = h
x = x << 5
a = a + x
a = a + h*4
h = a + h
and for h = a + h*37 we get
x = h + h*8
x = h + x*4
h = x + a*1
which is nearly twice as clever...
--
GPG: D5D4E405 - 2F9B BCCC 8527 692A 04E3 331E FAF8 226A D5D4 E405
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next prev parent reply other threads:[~2003-11-17 16:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E1AKPRR-00036l-00@surf.glug.org>
[not found] ` <8765hnf308.fsf@zagadka.ping.de>
[not found] ` <1068823738.13123.54.camel@localhost>
[not found] ` <20031114155148.GI16650@powergnu.laas.fr>
[not found] ` <1069058032.1638.21.camel@localhost>
[not found] ` <874qx3rogk.fsf@zagadka.ping.de>
2003-11-17 16:02 ` Does anyone have a better scm_string_hash ? Marius Vollmer
2003-11-17 16:29 ` Marius Vollmer [this message]
2003-11-18 20:15 ` Kevin Ryde
2003-11-19 9:04 ` Ludovic Courtès
2003-11-19 15:02 ` Marius Vollmer
2003-11-20 15:48 Stephen Compall
2003-11-20 17:29 ` Marius Vollmer
-- strict thread matches above, loose matches on Subject: below --
2003-11-14 18:11 Roland Orre
2003-11-14 20:09 ` Andreas Rottmann
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