From: David Howells <dhowells@redhat.com>
To: Namhyung Kim <namhyung@gmail.com>
Cc: dhowells@redhat.com, Arnd Bergmann <arnd@arndb.de>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] introduce ptr_diff()
Date: Thu, 19 Aug 2010 13:03:12 +0100 [thread overview]
Message-ID: <5790.1282219392@redhat.com> (raw)
In-Reply-To: <1282217856-8625-1-git-send-email-namhyung@gmail.com>
Namhyung Kim <namhyung@gmail.com> wrote:
> + if (is_power_of_2(__size)) \
> + __diff = (__addr1 - __addr2) >> ilog2(__size); \
> + else \
> + __diff = (__addr1 - __addr2) / __size; \
You shouldn't need to do this. The compiler's optimiser should switch a
divide to a shift for a power-of-2 divisor.
David
next prev parent reply other threads:[~2010-08-19 12:03 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-19 11:37 [RFC][PATCH] introduce ptr_diff() Namhyung Kim
2010-08-19 11:57 ` Bernd Petrovitsch
2010-08-19 12:03 ` David Howells [this message]
2010-08-19 16:18 ` Måns Rullgård
2010-08-19 12:23 ` Andi Kleen
2010-08-19 12:40 ` Matthew Wilcox
2010-08-19 12:58 ` Andi Kleen
2010-08-19 12:48 ` Bernd Petrovitsch
2010-08-19 12:59 ` Andi Kleen
2010-08-19 13:05 ` Bernd Petrovitsch
2010-08-19 13:39 ` Andi Kleen
2010-08-20 12:12 ` Al Viro
2010-08-19 15:53 ` Namhyung Kim
2010-08-19 16:04 ` Bernd Petrovitsch
2010-08-19 16:12 ` Namhyung Kim
2010-08-20 12:07 ` Al Viro
2010-08-20 12:49 ` Matthew Wilcox
2010-08-20 12:57 ` Andi Kleen
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