Remove real type

[Robert Jacques]

On Thu, 22 Apr 2010 20:51:44 -0300, bearophile <bearophileHUGS at lycos.com>  
wrote:
> BCS:
>> If you have no special reason to use float or double and are not IO or  
>> memory
>> space bound, use real. Every machine I know the details of will use it  
>> in
>> the FPU so the only general advantage to not using it is IO speed and  
>> data
>> size.
>
> Take one of the little ray-tracers written in D from my site, test its  
> running speed compiled with ldc, replace doubles with reals, and time it  
> again. You will see a nice performance difference. LDC FP performance is  
> not good if it doesn't use SSE registers.
>
> Bye,
> bearophile

Ray-tracers are insanely memory IO bound, not compute bound, bearophile.  
So what you're seeing is the difference between 80-bits and 64-bits of  
memory, not the FP performance.