regression in Newlib 4.2.0 (lgammaf)

[Andoni Arregi]

Dear Paul,

here again, although we can provide a fix, we cannot understand well
enough why this didn't seem to be present in Newlib 4.1.0. The source
code regarding the incorrect limit at |x|<2**-70 has been there since
decades.

Best regards

On Sat, 2022-02-05 at 07:38 +0100, Paul Zimmermann wrote:
>        Hi,
> 
> a third regression in Newlib 4.2.0 for single precision:
> 
> Checking lgamma with newlib-4.2.0.20211231
> MPFR library: 4.1.0       
> MPFR header:  4.1.0 (based on 4.1.0)
> Checking function mylgammaf with MPFR_RNDN
> libm wrong by up to 8.93e+43 ulp(s) for x=-0x1p-70
> mylgamma      gives inf
> mpfr_mylgamma gives 0x1.842994p+5
> 
> The largest error for lgammaf in Newlib 4.1.0 was 7.50e6 ulps
> (for x=-0x1.3a7fcap+1).
> 
> Paul

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Andoni Arregi
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