Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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: Linus Torvalds <torvalds@linux-foundation.org>
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include/linux/minmax.h
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include/linux/minmax.h
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#define __cmp(op, x, y) ((x) __cmp_op_##op (y) ? (x) : (y))
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#define __cmp_once(op, x, y, unique_x, unique_y) ({ \
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typeof(x) unique_x = (x); \
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typeof(y) unique_y = (y); \
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#define __cmp_once_unique(op, type, x, y, ux, uy) \
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({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
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#define __cmp_once(op, type, x, y) \
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__cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
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+
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#define __careful_cmp_once(op, x, y) ({ \
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static_assert(__types_ok(x, y), \
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#op "(" #x ", " #y ") signedness error, fix types or consider u" #op "() before " #op "_t()"); \
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__cmp(op, unique_x, unique_y); })
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__cmp_once(op, __auto_type, x, y); })
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#define __careful_cmp(op, x, y) \
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__builtin_choose_expr(__is_constexpr((x) - (y)), \
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__cmp(op, x, y), \
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__cmp_once(op, x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y)))
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__cmp(op, x, y), __careful_cmp_once(op, x, y))
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#define __clamp(val, lo, hi) \
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((val) >= (hi) ? (hi) : ((val) <= (lo) ? (lo) : (val)))
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* @x: first value
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* @y: second value
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*/
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#define min_t(type, x, y) __careful_cmp(min, (type)(x), (type)(y))
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#define min_t(type, x, y) __cmp_once(min, type, x, y)
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/**
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* max_t - return maximum of two values, using the specified type
···
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* @x: first value
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* @y: second value
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*/
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#define max_t(type, x, y) __careful_cmp(max, (type)(x), (type)(y))
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#define max_t(type, x, y) __cmp_once(max, type, x, y)
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/*
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* Do not check the array parameter using __must_be_array().