On Friday, 31 May 2013 at 01:26:13 UTC, 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)
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
Greetings.
After few fast changes I manage to get such results:
[raz@d3 tmp]$ ./a.out
rendering time 276 ms
[raz@d3 tmp]$ ./test
346 ms, 814 μs, and 5 hnsecs
./a.out being binary compiled with clang++ ./test.cxx -std=c++11
-lSDL -O3
./test being binary compiled with ldmd2 -O3 -release -inline
-noboundscheck ./test.d (Actually I used rdmd with
--compiler=ldmd2 but I omitted it because it was rather long cmd
line :p)
Here is source code with changes I applied to D-code (I hope you
don't mind repasting it): http://dpaste.dzfl.pl/84bb308d
I am sure there is way more room for improvements and at minimum
achieving C++ performance.
