darwin may lose primary target status on FSF gcc

[vincent habchi]

Jack,

> http://www.nabble.com/x86_64-apple-darwin-Polyhedron-2005-benchmarks-td25108861.html

These figures are very interesting, but I don't understand why they  
lack the gcc 4.2.4 -m64 performance; was that unavailable at that  
time? I would be also curious to see the relative performance of the  
two compilers on C-based scientific benchmarks (like BLAS or gsl or  
whatever). I know that because of aliasing, C compilers cannot  
optimize as much as Fortran ones do, but that may be at least partly  
solved by using the new C99 syntax.

It also raises other questions:

1. Could we compare those figures with the ones obtained with a  
"professional" compiler like, e.g. the Intel C/Fortran compilers for  
Mac?

2. What are the relative possibilities of progression of GCC and LLVM?  
I mean, maybe LLVM is lagging these days, but if the intermediate code  
representation it uses is potentially more powerful that the one  
chosen for GCC (as it is publicized), it might be just a matter of  
months before the results get close to a draw.

3. What is the place of Fortran in modern scientific computing  
compared to C-based languages? More specifically, in the scientific  
packages available in MacPorts like, e.g. SparseSuite, what part of  
the Fortran code is actively under development and what part is only  
legacy code?

4. What is the place of Open-CL? Of course, Open-CL is brand new, but  
with its capacities to unleashed massive parallel computing power, it  
could represent an awesome tool for matrix operations. Yet, I  
understand that due to the overhead of moving data to and fro the  
video RAM, Open-CL is inefficient for small matrix sizes; but that's  
also simply where optimization of CPU code is not really significant  
either.

Vincent