[cfg-branch] Iteration number counting using symbolic simplifications

[Jan Hubicka]

> Hello.
> 
> > > this patch adds the symbolic way of predicting number of iterations we've
> > > talked about.  I now have count_loop_iterations that count number of iterations
> > > in the stupid way - assuming that the loop is not paradoxical and
> > > test_for_iteration returning RTX expression of the comparison at given
> > > iteration count.
> > > 
> > Hi,
> > It has died in the stage3 of bootstrap, so I've fixed some bugs around and
> > re-started testing
> 
> I like it :-). The only thing I would change is:
OK,
I have to leave soon, so I am commiting the patch.  It built working cc1 for
stage3, I don't have time to wait for other optimizers, but I am optimistic :)

Honza