On Mon, 15 Dec 2014, James Greenhalgh wrote:
> > @@ -22792,6 +22792,12 @@ vsqrtq_f32 (float32x4_t a)
> > return __builtin_aarch64_sqrtv4sf (a);
> > }
> >
> > +__extension__ static __inline float64x1_t __attribute__
> > ((__always_inline__))
> > +vsqrt_f64 (float64x1_t a)
> > +{
> > + return (float64x1_t) { __builtin_sqrt (a[0]) };
> > +}
>
> Hi Kyrill,
>
> Does this introduce an implicit need to link against a maths library if
> we want arm_neon.h to work correctly? If so, I think we need to take a
> different approach.
>
> At O0 I've started to see:
>
> " undefined reference to `sqrt' "
>
> When checking a large arm_neon.h testcase.
>
> It does seem strange that the mid-end would convert a __builtin_sqrt back
> to a library call at O0 when the target has an optab for it, so perhaps
> there is a bug there to go hunt?
__builtin_sqrt has the same semantics as the sqrt library function. This
includes setting errno for negative arguments (other than -0 and -NaN).
The semantics also include that it's always OK to expand to a call to that
library function (generally, __builtin_foo may always expand to a call to
foo, if there is such a library function).
--
Joseph S. Myers
[email protected]
