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From:   Denis Efremov <efremov@linux.com>
To:     Julia Lawall <julia.lawall@inria.fr>
Cc:     Denis Efremov <efremov@linux.com>, cocci@systeme.lip6.fr,
        linux-kernel@vger.kernel.org
Subject: [PATCH v3] coccinelle: misc: add minmax script
Date:   Fri,  5 Mar 2021 13:16:40 +0300
Message-Id: <20210305101640.7717-1-efremov@linux.com>
In-Reply-To: <20210216160326.1341741-1-efremov@linux.com>
References: <20210216160326.1341741-1-efremov@linux.com>
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Check for opencoded min(), max() implementations.

Signed-off-by: Denis Efremov <efremov@linux.com>
---
Changes in v2:
 - <... ...> instead of ... when any
 - org mode reports fixed
 - patch rule to drop excessive ()
Changes in v3:
 - "depends on patch && (pmax || pmaxif || pmin || pminif)" fixed

 scripts/coccinelle/misc/minmax.cocci | 224 +++++++++++++++++++++++++++
 1 file changed, 224 insertions(+)
 create mode 100644 scripts/coccinelle/misc/minmax.cocci

diff --git a/scripts/coccinelle/misc/minmax.cocci b/scripts/coccinelle/misc/minmax.cocci
new file mode 100644
index 000000000000..f577f08d1e6e
--- /dev/null
+++ b/scripts/coccinelle/misc/minmax.cocci
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0-only
+///
+/// Check for opencoded min(), max() implementations.
+/// Generated patches sometimes require adding a cast to fix compile warning.
+/// Warnings/patches scope intentionally limited to a function body.
+///
+// Confidence: Medium
+// Copyright: (C) 2021 Denis Efremov ISPRAS
+// Options: --no-includes --include-headers
+//
+// Keywords: min, max
+//
+
+
+virtual report
+virtual org
+virtual context
+virtual patch
+
+@rmax depends on !patch@
+identifier func;
+expression x, y;
+binary operator cmp = {>, >=};
+position p;
+@@
+
+func(...)
+{
+	<...
+*	x cmp@p y ? x : y
+	...>
+}
+
+@rmaxif depends on !patch@
+identifier func;
+expression x, y;
+expression max_val;
+binary operator cmp = {>, >=};
+position p;
+@@
+
+func(...)
+{
+	<...
+*	if (x cmp@p y) {
+*		max_val = x;
+*	} else {
+*		max_val = y;
+*	}
+	...>
+}
+
+@rmin depends on !patch@
+identifier func;
+expression x, y;
+binary operator cmp = {<, <=};
+position p;
+@@
+
+func(...)
+{
+	<...
+*	x cmp@p y ? x : y
+	...>
+}
+
+@rminif depends on !patch@
+identifier func;
+expression x, y;
+expression min_val;
+binary operator cmp = {<, <=};
+position p;
+@@
+
+func(...)
+{
+	<...
+*	if (x cmp@p y) {
+*		min_val = x;
+*	} else {
+*		min_val = y;
+*	}
+	...>
+}
+
+@pmax depends on patch@
+identifier func;
+expression x, y;
+binary operator cmp = {>=, >};
+position p;
+@@
+
+func@p(...)
+{
+	<...
+-	x cmp y ? x : y
++	max(x, y)
+	...>
+}
+
+@pmaxif depends on patch@
+identifier func;
+expression x, y;
+expression max_val;
+binary operator cmp = {>=, >};
+position p;
+@@
+
+func@p(...)
+{
+	<...
+-	if (x cmp y) {
+-		max_val = x;
+-	} else {
+-		max_val = y;
+-	}
++	max_val = max(x, y);
+	...>
+}
+
+@pmin depends on patch@
+identifier func;
+expression x, y;
+binary operator cmp = {<=, <};
+position p;
+@@
+
+func@p(...)
+{
+	<...
+-	x cmp y ? x : y
++	min(x, y)
+	...>
+}
+
+@pminif depends on patch@
+identifier func;
+expression x, y;
+expression min_val;
+binary operator cmp = {<=, <};
+position p;
+@@
+
+func@p(...)
+{
+	<...
+-	if (x cmp y) {
+-		min_val = x;
+-	} else {
+-		min_val = y;
+-	}
++	min_val = min(x, y);
+	...>
+}
+
+@depends on patch && (pmax || pmaxif || pmin || pminif)@
+identifier func;
+expression x, y;
+position p;
+// FIXME: Coccinelle consumes all available ram and
+// and timeouts on every file.
+// position p = { pmin.p, pminif.p, pmax.p, pmaxif.p };
+@@
+
+func@p(...)
+{
+	<...
+(
+-	(min((x), (y)))
++	min(x, y)
+|
+-	(max((x), (y)))
++	max(x, y)
+)
+	...>
+}
+
+@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.org.print_todo(p[0], "WARNING opportunity for max()")
+
+@script:python depends on report@
+p << rmaxif.p;
+@@
+
+coccilib.report.print_report(p[0], "WARNING opportunity for max()")
+
+@script:python depends on org@
+p << rmaxif.p;
+@@
+
+coccilib.org.print_todo(p[0], "WARNING opportunity for max()")
+
+@script:python depends on report@
+p << rmin.p;
+@@
+
+coccilib.report.print_report(p[0], "WARNING opportunity for min()")
+
+@script:python depends on org@
+p << rmin.p;
+@@
+
+coccilib.org.print_todo(p[0], "WARNING opportunity for min()")
+
+@script:python depends on report@
+p << rminif.p;
+@@
+
+coccilib.report.print_report(p[0], "WARNING opportunity for min()")
+
+@script:python depends on org@
+p << rminif.p;
+@@
+
+coccilib.org.print_todo(p[0], "WARNING opportunity for min()")
-- 
2.26.2