[patch] Merge to trunk from Graphite branch

[Jack Howarth]

On Mon, Mar 15, 2010 at 03:11:21PM +0100, Richard Guenther wrote:
> 
> Sorry, but the biggest win for 4.5 is the various improvements
> SUSE / AMD has contributed to improve SPEC CPU 2006 scores
> (7% overall SPEC FP improvement).
> 
> Updating the default x86 arch does bring you nothing (well, if
> you're not clueless in case you shouldn't build GCC yourself).

   I mentioned that because of the 2% improvement in the Polyhedron
2005 benchmarks which coincided with the x86 arch changes which
enabled -msse2 across the board...

http://gcc.gnu.org/ml/gcc/2010-03/msg00075.html

> 
> As far as I know Graphite does not bring any performance advantages
> yet, so I see no reason to enable it by default.
> 
> If you want a specific benchmark to run faster you have to start
> analyzing why it is slow (it helps to have a competing compiler
> generate faster code), produce a testcase and at least file
> a missed-optimization bugreport.  Of course even better if you
> can think of a solution and implement it.
> 
> I am not aware of any major vectorization missed-optimizations
> vs for example the Intel compiler for SPEC CPU 2006.

    Don't we still lack the ability to vectorize the cases described
here?

http://gcc.gnu.org/ml/gcc/2009-08/msg00057.html

Perhaps current graphite already would handle some of those if the
vectorization wasn't getting accidentally lost.
                     Jack


> 
> Richard.
> 
> >> >                    Jack
> >