RFA: Patch to solve one PR37242 problem

[Jeff Law]

Vladimir Makarov wrote:
> The patch solves IR degradation on rethrow6.C reported in PR37242.
> 
> The analysis of the problem is in
> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37243
> 
> The solution is to prevent assigning hard-registers to global allocnos 
> for -O0 as the old register allocator does.
> 
> 2008-08-27  Vladimir Makarov  <vmakarov@redhat.com>
> 
>    PR rtl-opt/37243
>    * ira-color (ira_fast_allocation): Don't assign hard registers to
>    global allocnos.
> 
OK.  Please install if you haven't already.

Thanks,
Jeff