Matrix Multiplication benchmark

[Timon Gehr]

On 08/16/2012 03:15 PM, Matthias Pleh wrote:
> I've created a simple 4x4 Matrix struct and have made some tests, with
> surprising results. (although I've heard from similar results in c++)
>
> struct mat4 {
>   float[4][4] m;
>   mat4 opMul(in mat4 _m);
> }
> mat4 mul(in mat4 m1, in mat4 m2);
>
>
> I've tested this 2 multiplication functions (overloaded and free).
>
> Result (100_000 times, windows7 64bit, 32bit build):
>
> DMD: (dmd -O -inline -release)
> opMul: 20 msecs
> mul : 1355 msecs
>
> GDC: (gdc -m32 -O3 -frelease)
> opMul: 10 msecs
> mul : 1481 msecs
>
>
> Why this huge difference in performance?

Note that you have missed to provide the full benchmark code listing.