August 10, 2007
renoX Wrote:
> 2x?
> Your code must do a lot of 64b computation!

Yes.  Lots of 64-bit integer shifts of pointer values.  The only other difference is that 32-bit pointer addresses are closer together.  The result: The exact same code compiled for 32- or 64-bit has a 2x speed difference.

> When the AMD64 was released benchmarks made showed at best a 20% improvement, which is quite a lot to get with a simple recompilation assuming the code is 64b clean of course but is nowhere 2x.

Yes. 20% is a good rule of thumb.  That's what we usually see, for general object-oriented programming.  System-level programming is different.

I'll try gdc someday....