linux-kernel - Re: [RFC 3/3] kernel.h: use new typechecking macros in min()/max() and friends

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Message-ID: <1334437288.2528.111.camel@twins>
Date:	Sat, 14 Apr 2012 23:01:28 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Sasha Levin <levinsasha928@...il.com>
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	mingo@...e.hu, hpa@...or.com, tglx@...utronix.de,
	srivatsa.bhat@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org
Subject: Re: [RFC 3/3] kernel.h: use new typechecking macros in min()/max()
 and friends

On Sat, 2012-04-14 at 18:14 -0400, Sasha Levin wrote:
>  #define min(x, y) ({                           \
> -       typeof(x) _min1 = (x);                  \
> -       typeof(y) _min2 = (y);                  \
> -       (void) (&_min1 == &_min2);              \
> -       _min1 < _min2 ? _min1 : _min2; })
> +       typecmp2((x), (y));                             \
> +       (x) < (y) ? (x) : (y); }) 

Problem with this is that it evaluates x and y multiple times.
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