Re: [Qemu-devel] [PATCH v3 19/22] fpu/softfloat: re-factor scalbn

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

On 01/29/2018 03:59 AM, Alex Bennée wrote:
> 
> Richard Henderson <richard.henderson@linaro.org> writes:
> 
>> On 01/24/2018 05:13 AM, Alex Bennée wrote:
>>> +/* Multiply A by 2 raised to the power N.  */
>>> +static FloatParts scalbn_decomposed(FloatParts a, int n,
>>> +                                          float_status *s)
>>> +{
>>> +    if (a.cls == float_class_normal) {
>>> +        a.exp += n;
>>> +    }
>>> +    return a;
>>> +}
>>
>> ...
>>
>>> -    if ( aExp == 0x7FF ) {
>>> -        if ( aSig ) {
>>> -            return propagateFloat64NaN(a, a, status);
>>
>> This is where we used to raise inexact.
>> In the new function we need to handle this as in round_to_int.
> 
> Why is the handling in round_canonical not good enough for this?

This is scalbn -- you don't call round_canonical.


r~