[PATCH 7/8] math: Use stdbit.h instead of builtin in math_config.h

[Florian Weimer]

* Adhemerval Zanella:

> ---
>  sysdeps/ieee754/flt-32/math_config.h | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/sysdeps/ieee754/flt-32/math_config.h b/sysdeps/ieee754/flt-32/math_config.h
> index 6bb5c3324cc..230aee591ce 100644
> --- a/sysdeps/ieee754/flt-32/math_config.h
> +++ b/sysdeps/ieee754/flt-32/math_config.h
> @@ -23,6 +23,7 @@
>  #include <math_private.h>
>  #include <nan-high-order-bit.h>
>  #include <stdint.h>
> +#include <stdbit.h>
>  
>  #ifndef WANT_ROUNDING
>  /* Correct special case results in non-nearest rounding modes.  */
> @@ -77,7 +78,7 @@ roundeven_finite (double x)
>      {
>        union { double f; uint64_t i; } u = {y};
>        union { double f; uint64_t i; } v = {y - copysign (1.0, x)};
> -      if (__builtin_ctzll (v.i) > __builtin_ctzll (u.i))
> +      if (stdc_trailing_zeros (v.i) > stdc_trailing_zeros (u.i))
>          y = v.f;
>      }
>    return y;
> @@ -101,8 +102,8 @@ roundevenf_finite (float x)
>    if (fabs (x - y) == 0.5)
>      {
>        union { float f; uint32_t i; } u = {y};
> -      union { float f; uint32_t i; } v = {y - copysignf (1.0, x)};
> -      if (__builtin_ctzl (v.i) > __builtin_ctzl (u.i))
> +      union { float f; uint32_t i; } v = {y - copysignf (1.0f, x)};
> +      if (stdc_trailing_zeros (v.i) > stdc_trailing_zeros (u.i))
>          y = v.f;
>      }
>    return y;

Is this potentially a pessimization because stdc_trailing_zeros has a
defined value at zero?

Thanks,
Florian