Fix csin, csinh, ccos, ccosh missing underflows (bug 15405)

[Andreas Jaeger]

On 04/26/2013 07:15 PM, Joseph S. Myers wrote:
> On Fri, 26 Apr 2013, Andreas Jaeger wrote:
>
>>> +	  if (fabs (__real__ retval) < DBL_MIN)
>>> +	    {
>>> +	      volatile double force_underflow
>>> +		= __real__ retval * __real__ retval;
>>> +	      (void) force_underflow;
>>> +	    }
>>> +	  if (fabs (__imag__ retval) < DBL_MIN)
>>> +	    {
>>> +	      volatile double force_underflow
>>> +		= __imag__ retval * __imag__ retval;
>>> +	      (void) force_underflow;
>>> +	    }
>>
>> Couldn't this be an else if? I expect we only need to raise underflow once if
>> both are underflowing, aren't we?
>
> Generically the reason to avoid "else if" in such cases is to avoid issues
> in the case where the first part was an exact zero (so meets the if
> condition, but the multiplication shouldn't and doesn't cause underflow)
> while the second is a genuine underflow that needs the multiplication to
> get the exception.  Maybe the case of exact zero doesn't occur here, but
> it's more obvious without the "else" that the exception will always be
> raised if needed (and I don't think either the zero case or the underflow
> case is going to be the common case).


OK, then let's use the patch as is,

Thanks,
Andreas


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