Messages in this thread | | | Date | Tue, 12 Apr 2011 14:07:26 -0700 | From | Randy Dunlap <> | Subject | Re: [PATCH] remove abs64() |
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On Wed, 13 Apr 2011 00:00:45 +0300 Alexey Dobriyan wrote:
> We don't need no stinking abs64() given some GCC extensions > (especially __builtin_choose_expr()). > > One abs() implementation is better than two abs() implementations.
questionable.
> New abs() doesn't expand type needlessly. > > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> > --- > > drivers/gpu/drm/drm_irq.c | 4 ++-- > include/linux/kernel.h | 43 +++++++++++++++++++++---------------------- > lib/div64.c | 2 +- > 3 files changed, 24 insertions(+), 25 deletions(-)
> --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -143,28 +143,27 @@ extern int _cond_resched(void); > > #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) > > -/* > - * abs() handles unsigned and signed longs, ints, shorts and chars. For all > - * input types abs() returns a signed long. > - * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64() > - * for those. > - */ > -#define abs(x) ({ \ > - long ret; \ > - if (sizeof(x) == sizeof(long)) { \ > - long __x = (x); \ > - ret = (__x < 0) ? -__x : __x; \ > - } else { \ > - int __x = (x); \ > - ret = (__x < 0) ? -__x : __x; \ > - } \ > - ret; \ > - }) > - > -#define abs64(x) ({ \ > - s64 __x = (x); \ > - (__x < 0) ? -__x : __x; \ > - }) > +#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))))); \ > +})
that is better?
--- ~Randy
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