linux-kernel - Re: [PATCH] scripts: coccinelle: check for !(un)?likely usage

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Date:   Wed, 28 Aug 2019 15:41:43 +0300
From:   Denis Efremov <efremov@...ux.com>
To:     Julia Lawall <julia.lawall@...6.fr>
Cc:     Joe Perches <joe@...ches.com>, cocci@...teme.lip6.fr,
        linux-kernel@...r.kernel.org,
        Gilles Muller <Gilles.Muller@...6.fr>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Michal Marek <michal.lkml@...kovi.net>
Subject: Re: [PATCH] scripts: coccinelle: check for !(un)?likely usage


> 
> 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,
Denis