On 5/30/2013 6:26 PM, finalpatch wrote:
Recently I ported a simple ray tracer I wrote in C++11 to D. Thanks to the similarity between D and C++ it was almost a line by line translation, in other words, very very close. However, the D verson runs much slower than the C++11 version. On Windows, with MinGW GCC and GDC, the C++ version is twice as fast as the D version. On OSX, I used Clang++ and LDC, and the C++11 version was 4x faster than D verson. Since the comparison were between compilers that share the same codegen backends I suppose that's a relatively fair comparison. (flags used for GDC: -O3 -fno-bounds-check -frelease, flags used for LDC: -O3 -release)
For max speed using dmd, use the flags: -O -release -inline -noboundscheck The -inline is especially important.
I really like the features offered by D but it's the raw performance that's worrying me. From what I read D should offer similar performance when doing similar things but my own test results is not consistent with this claim. I want to know whether this slowness is inherent to the language or it's something I was not doing right (very possible because I have only a few days of experience with D). Below is the link to the D and C++ code, in case anyone is interested to have a look. https://dl.dropboxusercontent.com/u/974356/raytracer.d https://dl.dropboxusercontent.com/u/974356/raytracer.cpp
