Re: [PATCH] softfloat: Fix BAD_SHIFT from normalizeFloatx80Subnormal

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> All other calls to normalize*Subnormal detect zero input before
> the call -- this is the only outlier.  This case can happen with
> +0.0 + +0.0 = +0.0 or -0.0 + -0.0 = -0.0, so return a zero of
> the correct sign.
>
> Reported-by: Coverity (CID 1421991)
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Queued to for-5.0/random-fixes, thanks.

> ---
>  fpu/softfloat.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/fpu/softfloat.c b/fpu/softfloat.c
> index 301ce3b537..ae6ba71854 100644
> --- a/fpu/softfloat.c
> +++ b/fpu/softfloat.c
> @@ -5856,6 +5856,9 @@ static floatx80 addFloatx80Sigs(floatx80 a, floatx80 b, flag zSign,
>          zSig1 = 0;
>          zSig0 = aSig + bSig;
>          if ( aExp == 0 ) {
> +            if (zSig0 == 0) {
> +                return packFloatx80(zSign, 0, 0);
> +            }
>              normalizeFloatx80Subnormal( zSig0, &zExp, &zSig0 );
>              goto roundAndPack;
>          }


-- 
Alex Bennée