linux-kernel - Re: Improved Swapping Method In sort.c

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Message-ID: <alpine.LNX.1.10.0804301929360.5623@fbirervta.pbzchgretzou.qr>
Date:	Wed, 30 Apr 2008 19:30:45 +0200 (CEST)
From:	Jan Engelhardt <jengelh@...ozas.de>
To:	Soumyadip Das Mahapatra <dip_kernel@...oo.co.in>
cc:	linux-kernel@...r.kernel.org
Subject: Re: Improved Swapping Method In sort.c


On Wednesday 2008-04-30 19:09, Soumyadip Das Mahapatra wrote:

>Hello everybody, The swapping method (in function void u32_swap() line no.. 14
>to 16) in lib/sort.c can be improved by using the following code *(u32 *)b ^=
>*(u32 *)a ^= *(u32 *)b ^= *(u32 *)a instead of the code given.

GCC is smart enough to optimize the current instructions into a
bswap instruction or similar. While with xor, some are said to fail -
and three xor operations are surely slower than a swap if there is
a swap instruction.

Never heard of that?
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