Commit b280bb27 authored by David Laight's avatar David Laight Committed by Andrew Morton
Browse files

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.

Link: https://lkml.kernel.org/r/051afc171806425da991908ed8688a98@AcuMS.aculab.com


Signed-off-by: default avatarDavid Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 10666e99

include/linux/minmax.h

+12 −12
Original line number Diff line number Diff line
@@ -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)); })