[PATCH] Fix IVOPTs problem

[Daniel Berlin]

> > This is because of how the operand scanner works. The points-to set
> is 
> > attached to the pointer, and not pruned based on what the rest of
> the 
> > access expression is.
> Yes.  This was one of the things I wanted to fix with my aliasing
> changes, but alas, certain things have happened in my life which have
> prevented me from finishing that work.

Diego and I plan on fixing it on the new branch by passing down the
necessary info to be able to prune the set (or something of the sort).

> 
> 
> 
> > > I don't know our aliasing code well enough if there's a way to
> avoid
> > > the loss in precision when we transform the structure + array
> access
> > > into pointer arithmetic.
> > 
> > We can avoid some of the loss in the new aliaser (because it can
> figure 
> > out what offsets you can possibly point to, and what fields those 
> > offsets land on), but I punted on that for 4.1 in order to make
> deadlines 
> > because Diego wanted to put the new aliaser in :).

> Note that with this particular testcase, there isn't enough
> information
> in the TARGET_MEM_REF to know what the aliasing relationships should
> be.
> To properly determine the aliasing relationships we need to look at
> the
> whole loop to determine what values the index variable may have.

Yes, but we  know that from the scalar evolutions information and
bb->loop_father->number_of_iterations, when available. 

> 
> Jeff