Re: [PATCH] softfloat: Fix the incorrect computation in float32_exp2()

[Richard Henderson <richard.henderson@linaro.org>]

On 5/4/23 06:21, Shivaprasad G Bhat wrote:
> Hi Richard,
> 
> 
> On 5/3/23 01:11, Richard Henderson wrote:
>> On 5/2/23 16:25, Shivaprasad G Bhat wrote:
>>> The float32_exp2() is computing wrong exponent of 2.
>>> For example, with the following set of values {0.1, 2.0, 2.0, -1.0},
>>> the expected output would be {1.071773, 4.000000, 4.000000, 0.500000}.
>>> Instead, the function is computing {1.119102, 3.382044, 3.382044, -0.191022}
>>>
> <snip>
>>> his is because instead of the xnp which holds the numerator,
>>> parts_muladd is using the xp which is just 'x'. The commit '572c4d862ff2'
>>> refactored this function, and it seems mistakenly using xp instead of xnp.
>>>
>>> The patches fixes this possible typo.
>>>
>>> Fixes: 572c4d862ff2 "softfloat: Convert float32_exp2 to FloatParts"
>>> Partially-Resolves:https://gitlab.com/qemu-project/qemu/-/issues/1623
>>> Reported-By: Luca Barbato (https://gitlab.com/lu-zero)
>>> Signed-off-by: Shivaprasad G Bhat<sbhat@linux.ibm.com>
>>> Signed-off-by: Vaibhav Jain<vaibhat@linux.ibm.com>
>>> ---
>>>   fpu/softfloat.c |    2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Whoops.  Good catch.
>>
> 
> If you are fine with the patch, could you fix the mail id for Vaibhav Jain as
> 
>   <vaibhav@linux.ibm.com> while pulling ?

Done.  Queued to tcg-next.

r~