Re: [Discuss-gnuradio] ffast-math

[Albin Stigö]

ffast-math disables signed zero by design I think...

I'm particularly interested in problems of numeric stability and loss of dynamic range.

--Albin

On Mon, Sep 2, 2019, 15:27 Johannes Demel <address@hidden> wrote:

Hi Albin,

one of my students reported a little oddity about `-ffast-math`. Assume
you want to set a float to -0, i.e. set the sign bit only. In this case
`-ffast-math` seems to remove the sign bit.

In VOLK this might be an issue with `_mm256_conjugate_ps` in
`include/volk/volk_avx_intrinsics.h`. I didn't check for other potential
error sources.

Cheers
Johannes

Am 01.09.19 um 16:10 schrieb Albin Stigö:
> Anyone has experience with the real world impact of using gcc
> -ffast-math with SDR in general, and GNURadio/Volk in particular?
>
>
> --Albin SM6WJM
>
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