[PATCH] Fix expf overflow limit
Corinna Vinschen
vinschen@redhat.com
Thu Feb 10 15:01:51 GMT 2022
On Feb 9 14:52, Andoni Arregi wrote:
> Correct the overflow limit in the variable o_threshold to be consistent
> with the FLT_UWORD_LOG_MAX variable used by the internal implementation
> of the expf algorithm itself.
> The u_threshold variable has also been modified to be written in the
> same format.
>
> Note that this fix improves the situation but does not completely
> correct the inconsistencies regarding the overflow and underflow limits
> between the expf wrapper (wf_exp.c) and the expf algorithm itself
> (ef_exp.c).
>
> Currently these limits are different for the
> _FLT_LARGEST_EXPONENT_IS_NORMAL and _FLT_NO_DENORMALS cases as well as
> for the case where __OBSOLETE_MATH is not defined (only for the
> underflow limit in this case).
> ---
> newlib/libm/math/wf_exp.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/newlib/libm/math/wf_exp.c b/newlib/libm/math/wf_exp.c
> index 38cacd95a..075b5bb0a 100644
> --- a/newlib/libm/math/wf_exp.c
> +++ b/newlib/libm/math/wf_exp.c
> @@ -26,8 +26,8 @@ static const float
> #else
> static float
> #endif
> -o_threshold= 8.8721679688e+01, /* 0x42b17180 */
> -u_threshold= -1.0397208405e+02; /* 0xc2cff1b5 */
> +o_threshold= 0x1.62e42ep+06, /* 0x42b17217 */
> +u_threshold= -0x1.9fe36ap+06; /* 0xc2cff1b5 */
>
> #ifdef __STDC__
> float expf(float x) /* wrapper expf */
> --
> 2.35.1
Pushed.
Thanks,
Corinna
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