Commit 017fa3e8 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

minmax: simplify and clarify min_t()/max_t() implementation 



This simplifies the min_t() and max_t() macros by no longer making them
work in the context of a C constant expression.

That means that you can no longer use them for static initializers or
for array sizes in type definitions, but there were only a couple of
such uses, and all of them were converted (famous last words) to use
MIN_T/MAX_T instead.

Cc: David Laight <David.Laight@aculab.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4477b39c

include/linux/minmax.h

+11 −8
Original line number Diff line number Diff line
@@ -45,17 +45,20 @@ 


#define __cmp(op, x, y)	((x) __cmp_op_##op (y) ? (x) : (y))



#define __cmp_once(op, x, y, unique_x, unique_y) ({	\

	typeof(x) unique_x = (x);			\

	typeof(y) unique_y = (y);			\

#define __cmp_once_unique(op, type, x, y, ux, uy) \

	({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })



#define __cmp_once(op, type, x, y) \

	__cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))



#define __careful_cmp_once(op, x, y) ({			\

	static_assert(__types_ok(x, y),			\

		#op "(" #x ", " #y ") signedness error, fix types or consider u" #op "() before " #op "_t()"); \

	__cmp(op, unique_x, unique_y); })

	__cmp_once(op, __auto_type, x, y); })



#define __careful_cmp(op, x, y)					\

	__builtin_choose_expr(__is_constexpr((x) - (y)),	\

		__cmp(op, x, y),				\

		__cmp_once(op, x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y)))

		__cmp(op, x, y), __careful_cmp_once(op, x, y))



#define __clamp(val, lo, hi)	\

	((val) >= (hi) ? (hi) : ((val) <= (lo) ? (lo) : (val)))
@@ -158,7 +161,7 @@ 
 * @x: first value

 * @y: second value

 */

#define min_t(type, x, y)	__careful_cmp(min, (type)(x), (type)(y))

#define min_t(type, x, y) __cmp_once(min, type, x, y)



/**

 * max_t - return maximum of two values, using the specified type
@@ -166,7 +169,7 @@ 
 * @x: first value

 * @y: second value

 */

#define max_t(type, x, y)	__careful_cmp(max, (type)(x), (type)(y))

#define max_t(type, x, y) __cmp_once(max, type, x, y)



/*

 * Do not check the array parameter using __must_be_array().