Re: [Qemu-devel] [PATCH v5 01/28] fpu/softfloat: Fix conversion from uint64 to float128

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

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

> From: Petr Tesarik <ptesarik@suse.com>
>
> The significand is passed to normalizeRoundAndPackFloat128() as high
> first, low second. The current code passes the integer first, so the
> result is incorrectly shifted left by 64 bits.
>
> This bug affects the emulation of s390x instruction CXLGBR (convert
> from logical 64-bit binary-integer operand to extended BFP result).
>
> Cc: qemu-stable@nongnu.org
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Petr Tesarik <ptesarik@suse.com>
> Message-Id: <20180511071052.1443-1-ptesarik@suse.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  fpu/softfloat.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fpu/softfloat.c b/fpu/softfloat.c
> index bc0f52fa54..d07419324a 100644
> --- a/fpu/softfloat.c
> +++ b/fpu/softfloat.c
> @@ -3147,7 +3147,7 @@ float128 uint64_to_float128(uint64_t a, float_status *status)
>      if (a == 0) {
>          return float128_zero;
>      }
> -    return normalizeRoundAndPackFloat128(0, 0x406E, a, 0, status);
> +    return normalizeRoundAndPackFloat128(0, 0x406E, 0, a, status);

This brings back memories :-/

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

--
Alex Bennée