linux-kernel - [PATCH next 3/7] minmax.h: Reduce the #define expansion of min(), max() and clamp()

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Message-ID: <051afc171806425da991908ed8688a98@AcuMS.aculab.com>
Date: Mon, 18 Nov 2024 19:12:50 +0000
From: David Laight <David.Laight@...LAB.COM>
To: Linus Torvalds <torvalds@...ux-foundation.org>
CC: 'Arnd Bergmann' <arnd@...nel.org>, "'linux-kernel@...r.kernel.org'"
	<linux-kernel@...r.kernel.org>, 'Jens Axboe' <axboe@...nel.dk>, "'Matthew
 Wilcox'" <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>, "'Jason A . Donenfeld'" <Jason@...c4.com>,
	"'pedro.falcato@...il.com'" <pedro.falcato@...il.com>, 'Mateusz Guzik'
	<mjguzik@...il.com>, "'linux-mm@...ck.org'" <linux-mm@...ck.org>, "'Lorenzo
 Stoakes'" <lorenzo.stoakes@...cle.com>
Subject: [PATCH next 3/7] minmax.h: Reduce the #define expansion of min(),
 max() and clamp()

Since the test for signed values being non-negative only relies on
__builtion_constant_p() (not is_constexpr()) it can use the 'ux'
variable instead of the caller supplied expression.
This means that the #define parameters are only expanded twice.
Once in the code and once quoted in the error message.

Signed-off-by: David Laight <david.laight@...lab.com>
---
 include/linux/minmax.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index 24e4b372649a..6f7ea669d305 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -46,10 +46,10 @@
  * comparison, and these expressions only need to be careful to not cause
  * warnings for pointer use.
  */
-#define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux))
-#define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4))
-#define __sign_use(x, ux) (is_signed_type(typeof(ux)) ? \
-	__signed_type_use(x, ux) : __unsigned_type_use(x, ux))
+#define __signed_type_use(ux) (2 + __is_nonneg(ux))
+#define __unsigned_type_use(ux) (1 + 2 * (sizeof(ux) < 4))
+#define __sign_use(ux) (is_signed_type(typeof(ux)) ? \
+	__signed_type_use(ux) : __unsigned_type_use(ux))
 
 /*
  * Check whether a signed value is always non-negative.
@@ -71,13 +71,13 @@
 #else
   #define __signed_type(ux) typeof(__builtin_choose_expr(sizeof(ux) > 4, 1LL, 1L))
 #endif
-#define __is_nonneg(x, ux) statically_true((__signed_type(ux))(x) >= 0)
+#define __is_nonneg(ux) statically_true((__signed_type(ux))(ux) >= 0)
 
-#define __types_ok(x, y, ux, uy) \
-	(__sign_use(x, ux) & __sign_use(y, uy))
+#define __types_ok(ux, uy) \
+	(__sign_use(ux) & __sign_use(uy))
 
-#define __types_ok3(x, y, z, ux, uy, uz) \
-	(__sign_use(x, ux) & __sign_use(y, uy) & __sign_use(z, uz))
+#define __types_ok3(ux, uy, uz) \
+	(__sign_use(ux) & __sign_use(uy) & __sign_use(uz))
 
 #define __cmp_op_min <
 #define __cmp_op_max >
@@ -92,7 +92,7 @@
 
 #define __careful_cmp_once(op, x, y, ux, uy) ({		\
 	__auto_type ux = (x); __auto_type uy = (y);	\
-	BUILD_BUG_ON_MSG(!__types_ok(x, y, ux, uy),	\
+	BUILD_BUG_ON_MSG(!__types_ok(ux, uy),		\
 		#op"("#x", "#y") signedness error");	\
 	__cmp(op, ux, uy); })
 
@@ -109,7 +109,7 @@
 	static_assert(__builtin_choose_expr(__is_constexpr((lo) > (hi)), 	\
 			(lo) <= (hi), true),					\
 		"clamp() low limit " #lo " greater than high limit " #hi);	\
-	BUILD_BUG_ON_MSG(!__types_ok3(val, lo, hi, uval, ulo, uhi),		\
+	BUILD_BUG_ON_MSG(!__types_ok3(uval, ulo, uhi),				\
 		"clamp("#val", "#lo", "#hi") signedness error");		\
 	__clamp(uval, ulo, uhi); })
 
@@ -149,7 +149,7 @@
 
 #define __careful_op3(op, x, y, z, ux, uy, uz) ({			\
 	__auto_type ux = (x); __auto_type uy = (y);__auto_type uz = (z);\
-	BUILD_BUG_ON_MSG(!__types_ok3(x, y, z, ux, uy, uz),		\
+	BUILD_BUG_ON_MSG(!__types_ok3(ux, uy, uz),			\
 		#op"3("#x", "#y", "#z") signedness error");		\
 	__cmp(op, ux, __cmp(op, uy, uz)); })
 
-- 
2.17.1

-
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