From: "H. Peter Anvin" <hpa@zytor.com>
To: Petr Tesarik <ptesarik@suse.cz>
Cc: "Robert P. J. Day" <rpjday@crashcourse.ca>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] Introduce a boolean "single_bit_set" function.
Date: Mon, 29 Jun 2009 11:50:40 -0700 [thread overview]
Message-ID: <4A490D00.4020908@zytor.com> (raw)
In-Reply-To: <1243516357.8310.4.camel@nathan.suse.cz>
Petr Tesarik wrote:
>
> Ok, then my only concern is that the hweight* functions return the exact
> weight, which might be much less efficient if all we need is to know
> whether it's 1.
>
> Theoretically, gcc should be able to optimize things out, but I'm not
> all that optimistic about how well it does it.
>
I can almost guarantee it won't in this case.
-hpa
prev parent reply other threads:[~2009-06-29 18:51 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-23 17:43 [PATCH] Introduce a boolean "single_bit_set" function Robert P. J. Day
2009-04-23 19:57 ` David Daney
2009-04-23 20:11 ` Robert P. J. Day
2009-04-23 23:57 ` Andrew Morton
2009-04-24 10:40 ` Robert P. J. Day
2009-04-24 17:46 ` Andrew Morton
2009-04-25 22:09 ` Robert P. J. Day
2009-06-29 18:15 ` Petr Tesarik
2009-06-29 18:50 ` Robert P. J. Day
2009-06-30 6:12 ` Petr Tesarik
2009-06-30 10:18 ` Robert P. J. Day
2009-04-24 13:51 ` Robert P. J. Day
2009-05-28 12:21 ` Petr Tesarik
2009-05-28 12:27 ` Robert P. J. Day
2009-05-28 12:32 ` Robert P. J. Day
2009-05-28 13:12 ` Petr Tesarik
2009-06-29 18:50 ` H. Peter Anvin [this message]
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