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Subject: Re: [PATCH v2] scripts: coccinelle: check for !(un)?likely usage
To:     Denis Efremov <efremov@linux.com>, cocci@systeme.lip6.fr,
        kernel-janitors@vger.kernel.org,
        Gilles Muller <Gilles.Muller@lip6.fr>,
        Julia Lawall <Julia.Lawall@lip6.fr>,
        Joe Perches <joe@perches.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Nicolas Palix <nicolas.palix@imag.fr>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc:     linux-kernel@vger.kernel.org
References: <20190825130536.14683-1-efremov@linux.com>
 <20190829171013.22956-1-efremov@linux.com>
From:   Markus Elfring <Markus.Elfring@web.de>
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Date:   Fri, 30 Aug 2019 09:55:41 +0200
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> +/// Notations !unlikely(x) and !likely(x) are confusing.

I am curious if more software developers will share their views around
these likeliness annotations.

* How much does the scope matter for expressions?

* Are different coding style preferences involved?


> +//----------------------------------------------------------
> +//  For context mode
> +//----------------------------------------------------------
> +
> +@depends on context disable unlikely@

I wonder about the need for such a comment when the specification
of SmPL rule dependencies should be sufficient.


> +@depends on patch disable unlikely@
> +expression E;
> +@@
> +
> +(
> +-!likely(!E)
> ++unlikely(E)
> +|
> +-!likely(E)
> ++unlikely(!E)
> +|
> +-!unlikely(!E)
> ++likely(E)
> +|
> +-!unlikely(E)
> ++likely(!E)
> +)

Will another variant for the change specification with the semantic
patch language influence corresponding readability concerns?

+@replacement depends on patch disable unlikely@
+expression x;
+@@
+-!
+(
+(
+-unlikely
++likely
+|
+-likely
++unlikely
+)
+       (
+-       !
+        x
+       )
+|
+(
+-unlikely
++likely
+|
+-likely
++unlikely
+)
+       (
++       !
+        x
+       )
+)


Can the use of nested SmPL disjunctions help here together with
an other SmPL code formatting?

Regards,
Markus