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From: "George Spelvin" <linux@horizon.com>
To: linux@rasmusvillemoes.dk, yury.norov@gmail.com
Cc: akpm@linux-foundation.org, chris@chris-wilson.co.uk,
	davem@davemloft.net, dborkman@redhat.com,
	hannes@stressinduktion.org, klimov.linux@gmail.com,
	laijs@cn.fujitsu.com, linux-kernel@vger.kernel.org,
	linux@horizon.com, msalter@redhat.com,
	takahiro.akashi@linaro.org, tgraf@suug.ch,
	valentinrothberg@gmail.com, y.norov@samsung.com
Subject: Re: [PATCH v2 1/3] lib: find_*_bit reimplementation
Date: 2 Feb 2015 06:47:59 -0500	[thread overview]
Message-ID: <20150202114759.25525.qmail@ns.horizon.com> (raw)
In-Reply-To: <878uggr3tm.fsf@rasmusvillemoes.dk>

Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote:
> ... and this be part of _find_next_bit? Can find_next_bit not be simply
> 'return _find_next_bit(addr, size, offset, 1);', and similarly for
> find_next_zero_bit? Btw., passing true and false for the boolean
> parameter may be a little clearer.

Looking at the generated code, it would be better to replace the boolean
parameter with 0ul or ~0ul and XOR with it.  The same number of registers,
and saves a conditional branch.

(I was hoping GCC would figure that trick out, but it didn't.)

  reply	other threads:[~2015-02-02 11:48 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-31 20:58 yury.norov
2015-01-31 20:58 ` [PATCH v2 2/3] lib: move find_last_bit to lib/find_next_bit.c yury.norov
2015-01-31 20:58 ` [PATCH v2 3/3] lib: rename lib/find_next_bit.c to lib/find_bit.c yury.norov
2015-02-02 11:09   ` Rasmus Villemoes
2015-02-02  3:17 ` [PATCH v2 1/3] lib: find_*_bit reimplementation George Spelvin
2015-02-04 23:07   ` Yury
2015-02-02 10:43 ` Rasmus Villemoes
2015-02-02 11:47   ` George Spelvin [this message]
2015-02-02 12:56     ` Rasmus Villemoes
2015-02-04 23:45       ` Yury
2015-02-05 14:51         ` Rasmus Villemoes
2015-02-04 22:52   ` Yury
2015-02-05 15:01     ` Rasmus Villemoes
2015-02-05 23:07 Alexey Klimov

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