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: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-13 21:55 cmod-play 1 available + modsup.h additions Thien-Thi Nguyen
2003-11-14 8:26 ` Ludovic Courtès
2003-11-14 13:10 ` Thien-Thi Nguyen
2003-11-14 13:37 ` Ludovic Courtès
2003-11-14 17:38 ` Thien-Thi Nguyen
2003-11-14 14:29 ` Marius Vollmer
2003-11-14 14:17 ` Marius Vollmer
2003-11-14 15:28 ` Does anyone have a better scm_string_hash ? Roland Orre
2003-11-14 15:51 ` Ludovic Courtès
2003-11-17 8:33 ` Roland Orre
2003-11-17 13:01 ` Ludovic Courtès
2003-11-17 15:42 ` Marius Vollmer
2003-11-17 16:02 ` Marius Vollmer
2003-11-17 16:29 ` Marius Vollmer [this message]
2003-11-17 16:48 ` Allister MacLeod
2003-11-17 17:57 ` Marius Vollmer
2003-11-17 19:17 ` OT: x86 assembly timings/size (was Re: Does anyone have a better scm_string_hash ?) Allister MacLeod
2003-11-17 21:27 ` OT: x86 assembly timings/size Marius Vollmer
2003-11-19 9:04 ` Does anyone have a better scm_string_hash ? Ludovic Courtès
2003-11-19 15:02 ` Marius Vollmer
2003-11-14 17:40 ` cmod-play 1 available + modsup.h additions Thien-Thi Nguyen
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