Re: [OT] GCC vs Intel C++ compiler benchmark

[Andreas Jaeger <aj at suse dot de>]

Claus Fischer <claus.fischer@clausfischer.com> writes:

> The rather biased article on http://www.open-mag.com/754088105111.htm
> compares Intel's C++ favourably to GCC, without disclosing many
> enlightening details.
>
> I'm not concerned with that but with the notable OS difference
> between Linux (SuSE 7.3) and Windows (XP Pro). IMHO a CPU bound
> benchmark should see less than 1 % influence from OS and C library.
> The graphics shows roughly 7% better performance on Windows for the
> same (Intel) compiler.

I've done some measurements myself on Linux and the Intel compiler on
Linux is really superior. 


> Are there any ABI differences which would justify such a difference?

The Intel compiler uses different calling conventions for local
functions, can handle whole program optimizations, ...  I don't have a
full list of optimizations that the Intel compiler handles better but
it would be interesting to know what kind of optimizations really help
most for which CPUs.  

GCC 3.1 is in some areas already superior to GCC 3.0 and I expect
further improvements for the future with the ongoing projects like the
AST-Optimizer Branch, the new register allocator, midlevel RTL and the
work on the cfg-branch.

> Register use conventions? Other stuff that you could identify?
>
> Unfortunately the benchmark gives no details about compiler options,
> so presumably the answer is `the benchmark is flawed' and `go ask
> them'. In this case don't bother to answer.

Just have a look at my SPEC pages which also point to some Windows
results using the Intel Compilers as comparison:
http://www.suse.de/~aj,

Note, I didn't check the URL you've given,

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj