coccinelle: misc: add minmax script

Check for opencoded min(), max() implementations.
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>

scripts/coccinelle/misc/minmax.cocci

+// 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 = {>=, >};
+@@
+
+func(...)
+{
+	<...
+-	((x) cmp (y) ? (x) : (y))
++	max(x, y)
+	...>
+}
+
+@pmaxif depends on patch@
+identifier func;
+expression x, y;
+expression max_val;
+binary operator cmp = {>=, >};
+@@
+
+func(...)
+{
+	<...
+-	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 = {<=, <};
+@@
+
+func(...)
+{
+	<...
+-	((x) cmp (y) ? (x) : (y))
++	min(x, y)
+	...>
+}
+
+@pminif depends on patch@
+identifier func;
+expression x, y;
+expression min_val;
+binary operator cmp = {<=, <};
+@@
+
+func(...)
+{
+	<...
+-	if ((x) cmp (y)) {
+-		min_val = x;
+-	} else {
+-		min_val = y;
+-	}
++	min_val = min(x, y);
+	...>
+}
+
+@script:python depends on report@
+p << rmax.p;
+@@
+
+for p0 in p:
+	coccilib.report.print_report(p0, "WARNING opportunity for max()")
+
+@script:python depends on org@
+p << rmax.p;
+@@
+
+for p0 in p:
+	coccilib.org.print_todo(p0, "WARNING opportunity for max()")
+
+@script:python depends on report@
+p << rmaxif.p;
+@@
+
+for p0 in p:
+	coccilib.report.print_report(p0, "WARNING opportunity for max()")
+
+@script:python depends on org@
+p << rmaxif.p;
+@@
+
+for p0 in p:
+	coccilib.org.print_todo(p0, "WARNING opportunity for max()")
+
+@script:python depends on report@
+p << rmin.p;
+@@
+
+for p0 in p:
+	coccilib.report.print_report(p0, "WARNING opportunity for min()")
+
+@script:python depends on org@
+p << rmin.p;
+@@
+
+for p0 in p:
+	coccilib.org.print_todo(p0, "WARNING opportunity for min()")
+
+@script:python depends on report@
+p << rminif.p;
+@@
+
+for p0 in p:
+	coccilib.report.print_report(p0, "WARNING opportunity for min()")
+
+@script:python depends on org@
+p << rminif.p;
+@@
+
+for p0 in p:
+	coccilib.org.print_todo(p0, "WARNING opportunity for min()")