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From: Julia Lawall <julia.lawall@inria.fr>
To: Denis Efremov <efremov@linux.com>
Cc: cocci@systeme.lip6.fr, linux-kernel@vger.kernel.org
Subject: Re: [Cocci] [PATCH] coccinelle: misc: add minmax script
Date: Wed, 17 Feb 2021 22:17:56 +0100 (CET)
Message-ID: <alpine.DEB.2.22.394.2102172208030.3081@hadrien> (raw)
In-Reply-To: <20210216160326.1341741-1-efremov@linux.com>



On Tue, 16 Feb 2021, Denis Efremov wrote:

> Check for opencoded min(), max() implementations.

Some cases that could be improved:

diff -u -p a/drivers/platform/x86/asus-laptop.c
b/drivers/platform/x86/asus-laptop.c
--- a/drivers/platform/x86/asus-laptop.c
+++ b/drivers/platform/x86/asus-laptop.c
@@ -1195,7 +1195,7 @@ static ssize_t ls_level_store(struct dev
        if (rv < 0)
                return rv;

-       value = (0 < value) ? ((15 < value) ? 15 : value) : 0;
+       value = (0 < value) ? (min(15, value)) : 0;
        /* 0 <= value <= 15 */
        asus_als_level(asus, value);


diff -u -p a/sound/pci/ctxfi/ctatc.c b/sound/pci/ctxfi/ctatc.c
--- a/sound/pci/ctxfi/ctatc.c
+++ b/sound/pci/ctxfi/ctatc.c
@@ -382,7 +382,7 @@ static int atc_pcm_playback_start(struct
	apcm->started = 1;

        max_cisz = src->multi * src->rsc.msr;
-       max_cisz = 0x80 * (max_cisz < 8 ? max_cisz : 8);
+       max_cisz = 0x80 * (min(max_cisz, 8));


> +func(...)
> +{
> +	... when any
> +*	(x cmp y) ?@p x : y
> +	... when any
> +}

In all cases, this would be more efficient as:

func(...)
{
 <...
* (x cmp y) ?@p x : y
 ...>
}

There is an optimization that causes this to be just a search through the
nodes of the control-flow graph, rather than following the actual control
flow from the beginning of the function to the end.

> +@script:python depends on report@
> +p << rmax.p;
> +@@
> +
> +coccilib.report.print_report(p[0], "WARNING opportunity for max()")
> +
> +@script:python depends on org@
> +p << rmax.p;
> +@@
> +
> +coccilib.report.print_todo(p[0], "WARNING opportunity for max()")

All of the org cases should be coccilib.org, not coccilib.report.

julia
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Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-16 16:03 Denis Efremov
2021-02-17 21:17 ` Julia Lawall [this message]
2021-02-19  9:06 ` [Cocci] [PATCH v2 RESEND] " Denis Efremov
2021-03-06 14:08   ` Julia Lawall
2021-03-05 10:16 ` [Cocci] [PATCH v3] " Denis Efremov
2021-03-08  7:04 ` [Cocci] [PATCH v4] " Denis Efremov
2021-03-08 21:30   ` Julia Lawall
2021-03-09  6:39 ` [Cocci] [PATCH v5] " Denis Efremov
2021-03-20 21:31   ` Julia Lawall

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