Neal Becker <ndbecker2@xxxxxxxxx> writes:
> cmath has patterns like this (taking cos as an example):
>
> using ::cos;
>
> inline float
> cos(float __x)
> { return __builtin_cosf(__x); }
>
> inline long double
> cos(long double __x)
> { return __builtin_cosl(__x); }
>
> template<typename _Tp>
> inline typename __gnu_cxx::__enable_if<__is_integer<_Tp>::__value,
> double>::__type
> cos(_Tp __x)
> { return __builtin_cos(__x); }
>
> Do I understand correctly, that this means float, long double will use
> __builtin_cos(xxx), but plain double will not use __builtin_cos???
>
> I've tried tracing the generated code, and that's the way it looks. It
> appears to just call the cos function in glibc.
>
> Is this correct and if so, would not __builtin_cos be faster?
Unless you are using an unusual option like -ffreestanding, the compiler
should automatically recognize cos and treat it like __builtin_cos.
Ian
