Messages in this thread |  | | Date | Wed, 13 Apr 2011 22:20:31 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] remove abs64() |
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On 04/13, Andrew Morton wrote: > > On Wed, 13 Apr 2011 16:27:03 +0200 > Oleg Nesterov <oleg@redhat.com> wrote: > > > On 04/13, Alexey Dobriyan wrote: > > > > > > +#define abs(x) \ > > > +({ \ > > > + typeof(x) _x = (x); \ > > > + \ > > > + __builtin_choose_expr( \ > > > + __builtin_types_compatible_p(typeof(_x), signed char), \ > > > + (unsigned char)({ _x < 0 ? -_x : _x; }), \ > > > + __builtin_choose_expr( \ > > > + __builtin_types_compatible_p(typeof(_x), short), \ > > > + (unsigned short)({ _x < 0 ? -_x : _x; }), \ > > > + __builtin_choose_expr( \ > > > + __builtin_types_compatible_p(typeof(_x), int), \ > > > + (unsigned int)({ _x < 0 ? -_x : _x; }), \ > > > + __builtin_choose_expr( \ > > > + __builtin_types_compatible_p(typeof(_x), long), \ > > > + (unsigned long)({ _x < 0 ? -_x : _x; }), \ > > > + __builtin_choose_expr( \ > > > + __builtin_types_compatible_p(typeof(_x), long long), \ > > > + (unsigned long long)({ _x < 0 ? -_x : _x; }), \ > > > + _x))))); \ > > > +}) > > > > Personally I agree. > > > > But, we have some stupid users which do something like abs(u32_value) > > and expecting that abs() should treat this value as "signed". > > > > um, yes, I'd forgotten that one. That's a show-stopper.
May be we can demand to fix them?
I agree with Alexey, it is a bit ugly to have abs() and abs64(), and abs() itself doesn't look very nice.
What if we simply add
BUILD_BUG_ON( (typeof(_x)-1) > 0 );
into abs()?
After that it would be trivial to find the offenders and fix them,
- abs(unsigned_int) + abs((int) unsigned_int)
Oleg.
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