Loop optimization

[Don]

bearophile wrote:
> kai:
>> Any ideas? Am I somehow not hitting a vital compiler optimization?
> 
> DMD compiler doesn't perform many optimizations, especially on floating point computations.

More precisely:
In terms of optimizations performed, DMD isn't too far behind gcc. But 
it performs almost no optimization on floating point. Also, the inliner 
doesn't yet support the newer D features (this won't be hard to fix) and 
the scheduler is based on Pentium1.