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From: Denis Efremov <efremov@linux.com>
To: Julia Lawall <julia.lawall@lip6.fr>
Cc: Michal Marek <michal.lkml@markovi.net>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Nicolas Palix <nicolas.palix@imag.fr>,
	linux-kernel@vger.kernel.org, Joe Perches <joe@perches.com>,
	cocci@systeme.lip6.fr
Subject: Re: [Cocci] [PATCH] scripts: coccinelle: check for !(un)?likely usage
Date: Wed, 28 Aug 2019 16:57:26 +0300	[thread overview]
Message-ID: <e48665b3-eeb6-a258-18bb-779e09313e40@linux.com> (raw)
In-Reply-To: <496b3d09-47a2-3836-2899-d964267993d3@linux.com>

On 8/28/19 3:41 PM, Denis Efremov wrote:
> 
>>
>> As a human I am confused. Is !likely(x) equivalent to x or !x?
>>
>> Julia
>>
> 
> As far as I could understand it:
> 
> # define likely(x)	__builtin_expect(!!(x), 1)
> !likely(x)
> !__builtin_expect(!!(x), 1)
> !((!!(x)) == 1)
> (!!(x)) != 1, since !! could result in 0 or 1
> (!!(x)) == 0
> !(!!(x))
> !!!(x)
> !(x)
> 

Thanks Rasmus for the explanation, this should be:
!likely(x)
!__builtin_expect(!!(x), 1)
!(!!(x))
!!!(x)
!(x)

Denis

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WARNING: multiple messages have this Message-ID (diff)
From: Denis Efremov <efremov@linux.com>
To: Julia Lawall <julia.lawall@lip6.fr>
Cc: Joe Perches <joe@perches.com>,
	cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org,
	Gilles Muller <Gilles.Muller@lip6.fr>,
	Nicolas Palix <nicolas.palix@imag.fr>,
	Michal Marek <michal.lkml@markovi.net>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: Re: [PATCH] scripts: coccinelle: check for !(un)?likely usage
Date: Wed, 28 Aug 2019 16:57:26 +0300	[thread overview]
Message-ID: <e48665b3-eeb6-a258-18bb-779e09313e40@linux.com> (raw)
In-Reply-To: <496b3d09-47a2-3836-2899-d964267993d3@linux.com>

On 8/28/19 3:41 PM, Denis Efremov wrote:
> 
>>
>> As a human I am confused. Is !likely(x) equivalent to x or !x?
>>
>> Julia
>>
> 
> As far as I could understand it:
> 
> # define likely(x)	__builtin_expect(!!(x), 1)
> !likely(x)
> !__builtin_expect(!!(x), 1)
> !((!!(x)) == 1)
> (!!(x)) != 1, since !! could result in 0 or 1
> (!!(x)) == 0
> !(!!(x))
> !!!(x)
> !(x)
> 

Thanks Rasmus for the explanation, this should be:
!likely(x)
!__builtin_expect(!!(x), 1)
!(!!(x))
!!!(x)
!(x)

Denis


  reply	other threads:[~2019-08-28 13:57 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-25 13:05 [Cocci] [PATCH] scripts: coccinelle: check for !(un)?likely usage Denis Efremov
2019-08-25 13:05 ` Denis Efremov
2019-08-25 15:30 ` [Cocci] " Markus Elfring
2019-08-25 15:30   ` Markus Elfring
2019-08-25 21:06   ` [Cocci] " Denis Efremov
2019-08-25 21:06     ` Denis Efremov
2019-08-25 15:30 ` [Cocci] " Markus Elfring
2019-08-25 15:30   ` Markus Elfring
2019-08-25 16:37 ` [Cocci] " Joe Perches
2019-08-25 16:37   ` Joe Perches
2019-08-25 18:59   ` [Cocci] " Denis Efremov
2019-08-25 18:59     ` Denis Efremov
2019-08-25 19:19     ` [Cocci] " Julia Lawall
2019-08-25 19:19       ` Julia Lawall
2019-08-28 11:33       ` [Cocci] " Rasmus Villemoes
2019-08-28 11:33         ` Rasmus Villemoes
2019-08-28 11:59         ` [Cocci] " Joe Perches
2019-08-28 11:59           ` Joe Perches
2019-08-28 12:33         ` [Cocci] " Denis Efremov
2019-08-28 12:33           ` Denis Efremov
2019-08-28 13:05           ` Rasmus Villemoes
2019-08-28 13:14             ` Denis Efremov
2019-08-28 12:33         ` [Cocci] " Julia Lawall
2019-08-28 12:33           ` Julia Lawall
2019-08-28 12:41       ` [Cocci] " Denis Efremov
2019-08-28 12:41         ` Denis Efremov
2019-08-28 13:57         ` Denis Efremov [this message]
2019-08-28 13:57           ` Denis Efremov
2019-08-25 21:19     ` [Cocci] " Denis Efremov
2019-08-25 21:19       ` Denis Efremov
2019-09-01 17:24   ` Pavel Machek
2019-09-01 17:39     ` [Cocci] " Denis Efremov
2019-09-01 17:39       ` Denis Efremov
2019-08-29 17:10 ` [Cocci] [PATCH v2] " Denis Efremov
2019-08-29 17:10   ` Denis Efremov
2019-08-29 17:13   ` [Cocci] " Denis Efremov
2019-08-29 17:13     ` Denis Efremov
2019-08-30  0:42     ` [Cocci] " Julia Lawall
2019-08-30  0:42       ` Julia Lawall
2019-08-30  6:56       ` [Cocci] " Denis Efremov
2019-08-30  6:56         ` Denis Efremov
2019-08-30  8:06         ` [Cocci] " Rasmus Villemoes
2019-08-30  8:06           ` Rasmus Villemoes
2019-08-29 20:07   ` [Cocci] " Markus Elfring
2019-08-29 20:07     ` Markus Elfring
2019-08-30  7:55   ` [Cocci] " Markus Elfring
2019-08-30  7:55     ` Markus Elfring
2019-08-30  7:55     ` Markus Elfring
2019-09-06 20:19   ` [Cocci] " Julia Lawall
2019-09-06 20:19     ` Julia Lawall
2019-09-06 20:55     ` [Cocci] " Denis Efremov
2019-09-06 20:55       ` Denis Efremov
2019-09-07  8:05       ` [Cocci] [v2] " Markus Elfring
2019-09-07  8:05         ` Markus Elfring

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