linux-kernel - [PATCH 5/7] minmax: Factor out the zero-extension logic from umin/umax

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Message-ID: <f19f6d98fba44c39b347f3c0fbb5bdba@AcuMS.aculab.com>
Date: Wed, 24 Jul 2024 14:31:45 +0000
From: David Laight <David.Laight@...LAB.COM>
To: "'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>, "'Linus
 Torvalds'" <torvalds@...uxfoundation.org>
CC: "'Matthew Wilcox (Oracle)'" <willy@...radead.org>, 'Christoph Hellwig'
	<hch@...radead.org>, 'Andrew Morton' <akpm@...ux-foundation.org>, "'Andy
 Shevchenko'" <andriy.shevchenko@...ux.intel.com>, 'Dan Carpenter'
	<dan.carpenter@...aro.org>, 'Arnd Bergmann' <arnd@...nel.org>,
	"'Jason@...c4.com'" <Jason@...c4.com>, "'hch@...radead.org'"
	<hch@...radead.org>, "'pedro.falcato@...il.com'" <pedro.falcato@...il.com>,
	'Mateusz Guzik' <mjguzik@...il.com>, "'linux-mm@...ck.org'"
	<linux-mm@...ck.org>
Subject: [PATCH 5/7] minmax: Factor out the zero-extension logic from
 umin/umax

The '+ 0u + 0ul + 0ull' to zero extend to 64bit on both 32bit and
64bit systems was replicated 4 times.
Factor out and then join up some 'not overlong' lines.

Signed-off-by: David Laight <david.laight@...lab.com>
---
 include/linux/minmax.h | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index d3ac65c1add7..e250957036a1 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -28,7 +28,7 @@
 
 /* Allow unsigned compares against non-negative signed constants. */
 #define __is_ok_unsigned(x) \
-	((is_unsigned_type(typeof(x)) ? 0 : __if_constexpr(x, (x) + 0, -1)) >= 0)
+	((is_unsigned_type(typeof(x)) ? 0 : __if_constexpr(x, x, -1)) >= 0)
 
 /* Check for signed after promoting unsigned char/short to int */
 #define __is_ok_signed(x) is_signed_type(typeof((x) + 0))
@@ -69,22 +69,26 @@
  */
 #define max(x, y)	__careful_cmp(max, x, y)
 
+/*
+ * Zero extend a non-negative value to 64bits.
+ * Undefined for negative values.
+ * The extension to 64 bits is often optimised away.
+ */
+#define __zero_extend(x) ((x) + 0u + 0ul + 0ull)
+
 /**
  * umin - return minimum of two non-negative values
- *   Signed types are zero extended to match a larger unsigned type.
  * @x: first value
  * @y: second value
  */
-#define umin(x, y)	\
-	__careful_cmp(min, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull)
+#define umin(x, y)	__careful_cmp(min, __zero_extend(x), __zero_extend(y))
 
 /**
  * umax - return maximum of two non-negative values
  * @x: first value
  * @y: second value
  */
-#define umax(x, y)	\
-	__careful_cmp(max, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull)
+#define umax(x, y)	__careful_cmp(max, __zero_extend(x), __zero_extend(y))
 
 /**
  * min3 - return minimum of three values
-- 
2.17.1

-
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