Re: [PATCH] target: i386: Check float overflow about register stack

[Chen Gang]

On 2020/2/24 下午8:43, Paolo Bonzini wrote:
> On 22/02/20 13:25, Chen Gang wrote:
>> On 2020/2/22 下午3:37, Paolo Bonzini wrote:
>>> On 22/02/20 03:10, Chen Gang wrote:
>>>> Set C1 to 1 if stack overflow occurred; set to 0 otherwise".
>>>>
>>>> In helper_fxam_ST0, I guess, we need "env->fpus |= 0x200" (but I don't
>>>> know wheter it will be conflict with SIGND(temp)). And we have to still
>>>> need foverflow, because all env->fptags being 0 doesn't mean overflow.
>>>
>>> No, you need to add "env->fpus |= 0x200" and "env->fpus &= ~0x200"
>>> directly to fpush, fpop, etc.
>>>
>>
>> OK. The content below is my next TODO, welcome your opinions.
>>
>> When overflow occurs, for me, we need keep everything no touch except
>> set C1 flag.
> 
> No, push will overwrite the top entry if there is overflow.
> 
>> In fxam, we don't clear C1, but keep no touch for clearning
>> C1 in another places.
> 
> FXAM is neither push nor pop, it just detects an empty slot via fptags.
>  FXAM should be okay with my patch.
> 

OK. I am not quite clear about it, but it fixes the current issues at
least. Please apply your patch.

Thanks.