From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Matthew Wilcox <mawilcox@linuxonhyperv.com>
Cc: Yury Norov <yury.norov@gmail.com>,
George Spelvin <linux@horizon.com>,
Akinobu Mita <akinobu.mita@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Matthew Wilcox <mawilcox@microsoft.com>
Subject: Re: [PATCH] find_bit: Micro-optimise find_next_*_bit
Date: Fri, 23 Dec 2016 21:43:46 +0100 [thread overview]
Message-ID: <878tr65qbh.fsf@rasmusvillemoes.dk> (raw)
In-Reply-To: <1482513603-9630-1-git-send-email-mawilcox@linuxonhyperv.com> (Matthew Wilcox's message of "Fri, 23 Dec 2016 09:20:03 -0800")
On Fri, Dec 23 2016, Matthew Wilcox <mawilcox@linuxonhyperv.com> wrote:
> From: Matthew Wilcox <mawilcox@microsoft.com>
>
> First, the first half of the test: (!nbits || start >= nbits) is
> trivially a subset of the second half, since nbits and start are both unsigned.
Yeah, I filed that as a missed optimization bug with gcc a year ago, but
it seems that even 6.3 still does two tests - clang 3.6 is a bit
smarter. Anyway,
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
next prev parent reply other threads:[~2016-12-23 20:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-23 17:20 [PATCH] find_bit: Micro-optimise find_next_*_bit Matthew Wilcox
2016-12-23 20:43 ` Rasmus Villemoes [this message]
2016-12-24 6:43 ` Yury Norov
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