Re: [PATCH 5/5] target/loongarch: div if x/0 set dividend to 0

[Qi Hu]

On 2022/9/19 19:45, gaosong wrote:
> 在 2022/9/17 下午6:12, Richard Henderson 写道:
> > On 9/17/22 11:12, gaosong wrote:
> > > 在 2022/9/17 下午4:59, Qi Hu 写道:
> > > > On 2022/9/17 15:59, Song Gao wrote:
> > > > > div.d, div.du, div,w, div.wu, the LoongArch host if x/0  the 
> > > > > result is 0.
> > > >
> > > > The message has a typo: "div,w" => "div.w"
> > > >
> > > > Also I don't know why we need to do this, since the manual say: 
> > > > "When the divisor is 0, the result can be any value".
> > > I tested on LoongArch host,   the result is always 0.
> >
> > But it is legal for a different loongarch host implementation to 
> > return some other value.  Therefore the test itself is not correct.
> I think the manual maybe not correct,  the hardware engineer said that 
> they need to comfirm  whether the result is always 0.
>
> Thanks.
> Song Gao

Hi,

The hardware designers suggested that 0 should not be used as the 
default value when "div 0" occurs. The behavior is not guaranteed in 
future processors.

So I think there are some ways to solve this:

- Remove this case("div 0") from risu test.

- Keep this patch by yourself. If you want to do risu test, patch it. :-)


regards,

Qi

> > r~