Woeful performance of D compared to C++

[Bill Lear]

Pragma <ericanderton at yahoo.removeme.com> writes:

> rael at seesig.com wrote:
> > In other benchmarks I've seen, D seems quite competitive with C/C++.
> > I seem to have written a very simple program that shows D in a very
> > poor light compared to C++.  I wonder if it is my inexperience.
> [snip]
> > Any help would be appreciated.
> 
> I'm gobsmacked.  No array concatenation, strings, large allocations,
> or even floating point.  Just integer math and comparisons.
> 
> Check the obvious stuff first: disable the GC, compile with "-inline
> -release" for GDC to match the "-O3 -o" that you're using on GCC.

Hmm, tried -release and -O -inline, but not disable GC.  I'll
throw a spare whirl that way and see how that goes.

> The only part of that loop that is of any consequence is the call to
> rand() - odds are they are two completely different algorithms, with
> D's being slower (performance test anyone?).  Everything else should
> reduce to almost the same exact machine code.

The rand() call is definitely the most expensive.  When I remove it
from both the C++ and the D program, the times plummet (to 0.003
and 0.013 seconds, respectively --- still, however, leaving the D
program running in 4.3 times that of the C++ program;-).


Bill
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Bill Lear
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