GDC release 0.23

[Anders F Björklund]

Don Clugston wrote:

>>>> Older versions of PPC operating systems used 64-bit for "long double",
>>>> newer versions use 128-bit. Both are still in use, so we won't know.
>>>
>>> Ugh. That's really horrible.
>>
>> It's called progress :-)
> 
> I was referring to the entire section, not just that line.

Seriously, there was a lot of effort put into supporting 128-bit
long doubles - but I guess it was done with less emphasis on it
being IEEE correct and handling exceptions then what D demands ?

The D spec should probably mention whether it absolutely requires
the type to conform to the IEEE floating-point standard or not...
i.e. whether it should just map over to C/C++ "long double" or not.

>> I'll let David decide which one wins: D real === C long double, or
>> the definition of "largest hardware implemented floating point size"
> 
> There's just no way D real can be equal to C long double in general, 
> when the C long double is playing silly games. The only reason gcc can 
> even do that, is that the C spec for floating point is ridiculously 
> vague, and consequently no-one actually uses long double. To mimic it is 
> to immediately break D's support for IEEE.

We can equate D "real" with C "long double", and just avoid using
it on those platforms where it doesn't match the hardware size ?
But then "real" would be a bad name for it, that I agree with...

> Seriously, the viability of D as a numeric computing platform is at 
> stake here.

Only on the PowerPC platform, though. Maybe on SPARC too, not sure.
(it might have real 128-bit ?) But not on the DMD platform: Intel,
there it will have full 80-bit support (even if not too portable).

--anders