[LLVMdev] gfortran benchmarks

[Bill Wendling]

On Jan 24, 2009, at 7:35 PM, Jack Howarth wrote:

>   Since the fact that gfortran performance has improved
> over the major releases, I decided to benchmark the current
> releases on a MacPro with the Polyhedron 2005 benchmarks
> using -ffast-math -funroll-loops -msse3 -O3. The results
> are...
>
>                    gcc release
>            gcc 4.2.4      gcc 4.3.3    gcc 4.4-pre   gcc 4.3.3/    
> gcc 4.4-pre/
>                                                      gcc 4.2.4     
> gcc 4.2.4
> ac          15.32          13.04        12.65         0.851         
> 0.826
> aermod      22.96          26.65        25.52         1.161         
> 1.111
> air         8.15           7.58         7.10          0.930         
> 0.871
> capacita    52.16          52.45        49.56         1.006         
> 0.950
> channel     5.17           3.39         1.81          0.656         
> 0.350
> doduc       34.43          34.89        35.28         1.013         
> 1.025
> fatigue     12.57          10.92        10.13         0.869         
> 0.806
> gas_dyn     13.59          7.68         7.63          0.565         
> 0.561
> induct      28.61          48.46        14.88         1.694         
> 0.520
> linpk       15.46          15.48        15.50         1.001         
> 1.003
> mdbx        12.41          12.94        12.36         1.043         
> 0.996
> nf          27.08          27.25        25.50         1.006         
> 0.942
> protein     41.61          41.18        39.12         0.990         
> 0.940
> rnflow      35.37          32.58        30.68         0.921         
> 0.867
> test_fpu    11.94          10.79        10.50         0.904         
> 0.879
> tfft        2.13           2.11         2.08          0.991         
> 0.977
>
> Certainly it would be nice eventually resync llvm-gcc against  
> something
> newer.

There are some heavy licensing issues involved in this (which I won't  
go into here) that make this difficult. I don't think that the problem  
is the version of GCC we're using as a front-end, but rather how our  
optimizations perform compared with GCC's optimizations. We don't  
really use any of GCC's optimizations for the code we generate.

-bw