Re: [Qemu-devel] [PATCH v4 1/4] target-tilegx: Add floating point shared functions

[Richard Henderson <rth@twiddle.net>]

On 12/24/2015 07:38 AM, Chen Gang wrote:
>
> On 12/24/15 06:51, Richard Henderson wrote:
>> On 12/23/2015 01:48 PM, chengang@emindsoft.com.cn wrote:
>>> +extern float_status fp_status;
>>
>> No.  Locally declared in e.g. main_calc.
>>
>
> OK, thanks. Since fp_status need to be initialized to be 0, so I will
> declared it statically, too (need we consider about thread safe for it?
> I guess not).

While qemu is not currently thread-safe, there's work going on to make that 
happen.  There is no need to exacerbate the problem.

Also, I think using an on-stack automatic variable, initialized each time, 
emphasizes the fact there there is no state that is preserved across operations.

This should really be as simple as

   float_status fp_status = {
     .float_rounding_mode = float_round_nearest_even
   };

(I realize float_round_nearest_even is *also* zero, but humor me.  At least the 
other members are either flags or booleans.)


r~