[tree-ssa] some manual store sinking for tree-dfa

[Jan Hubicka]

> 
> Measuring with ENABLE_CHECKING enabled and no optimization can be
> misleading :-)

Well, most of my CPU cycles are spent by such a compiler so it is the
only mode where I do worry about performance :), and I was
measuring perofmrance of verify_ssa that would not be very interesting
without checking.
> 
> I'll add it once everything is working. Im "enjoying" getting everything
> working in the presence of all the GGCing between phases now :-)

Good luck then :)

Honza
> 
> Andrew