On Wednesday, 9 September 2015 at 07:59:48 UTC, qznc wrote:
I'm not sure if I understand you correctly. What is "high
level" and "low level" optimization?
Low level are local optimizations, which basically will be the
same if you use the same backend (like LLVM). It would just
measure the programmer's approach and not the compiler.
What I want to know is a) how fast is "idiomatic" D code (using
ranges etc) compared to "idiomatic" C/C++ and b) how do they
compare if you push performance to the limits (code beauty be
damned).
For a) you want a similar implementation although C/C++ will
most certainly always loose in terms of length and convenience.
For b) we don't care. C/C++ is free to use builtins, pragmas,
and whatnot. If for loops are faster than ranges in D, then we
will use for loops here.
The problem with a) is that in C++ there are many libraries and
you'll have a hard time finding comparable alternatives on both
sides... People don't stick to the standard libraries in C++.
For b) C++ will be slightly faster because of things like modular
arithmetics and OpenMP support.
I think the better approach is to write up the same algorithms in
a high level fashion (using generic templates on both sides) from
the ground up using the same constructs and measure the ability
to optimize.
Otherwise you end up comparing apples and oranges in a rather
subjective manner.
