N-body bench

[Stanislav Blinov]

On Thursday, 30 January 2014 at 16:53:22 UTC, bearophile wrote:

> Yes. The older version of LDC2 doesn't even compile the code. I 
> need to use 0.13.0-alpha1.

Hmm.

> Your D code with small changes:
> http://codepad.org/xqqScd42

That won't compile with dmd (at least, with 2.064.2): it expects 
constants as initializers for vectors. :( That's why I rolled up 
that toDouble2() function.

> With N = 5_000_000 my timings on an old CPU are 2.23 seconds 
> for ldc2 and 1.83 seconds for g++. So there's some performance 
> difference.

What about 50_000_000?

>
> I have tried to unroll manually the loop in the D code, but I 
> see worse performance. I'll try some more later.

I'm also fiddling :)