It is enough to check that both 'x' and 'y' are valid for either a signed compare or an unsigned compare. For unsigned they must be an unsigned type or a positive constant. For signed they must be signed after unsigned char/short are promoted. Order the expressions to avoid warnings about comparisons that are always true. Signed-off-by: David Laight <david.laight@xxxxxxxxxx> --- Changes for v2: - Wrap is_signed_type() to avoid issues with pointer types because (foo *)1 isn't a compile time constant. - Remove the '+ 0' from __is_ok_unsigned(). This converted 'bool' to 'int' to avoid a compiler warning and is no longer needed because of the implicit conversion dome by ?:. include/linux/minmax.h | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index ab64b2e73ae5..b9b5348a3879 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -8,7 +8,7 @@ #include <linux/types.h> /* - * min()/max()/clamp() macros must accomplish three things: + * min()/max()/clamp() macros must accomplish several things: * * - Avoid multiple evaluations of the arguments (so side-effects like * "x++" happen only once) when non-constant. @@ -26,19 +26,20 @@ #define __typecheck(x, y) \ (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) -/* is_signed_type() isn't a constexpr for pointer types */ -#define __is_signed(x) \ - __builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))), \ - is_signed_type(typeof(x)), 0) +#define __is_signed(x) \ + __if_constexpr((typeof(x))1, is_signed_type(typeof(x)), 0) -/* True for a non-negative signed int constant */ -#define __is_noneg_int(x) \ - (__builtin_choose_expr(__is_constexpr(x) && __is_signed(x), x, -1) >= 0) +/* Allow unsigned compares against non-negative signed constants. */ +#define __is_ok_unsigned(x) \ + ((!__is_signed((x)) ? 0 : __if_constexpr(x, x, -1)) >= 0) -#define __types_ok(x, y) \ - (__is_signed(x) == __is_signed(y) || \ - __is_signed((x) + 0) == __is_signed((y) + 0) || \ - __is_noneg_int(x) || __is_noneg_int(y)) +/* Check for signed after promoting unsigned char/short to int */ +#define __is_ok_signed(x) __is_signed((x) + 0) + +/* Allow if both x and y are valid for either signed or unsigned compares. */ +#define __types_ok(x, y) \ + ((__is_ok_signed(x) && __is_ok_signed(y)) || \ + (__is_ok_unsigned(x) && __is_ok_unsigned(y))) #define __cmp_op_min < #define __cmp_op_max > -- 2.17.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
