Prevent copy propagation from a non-frame related insn to a frame related insn

[Eric Botcazou]

> I would deeply appreciate if the community can provide feedback as to
> whether preventing hardreg copy propagation based on the frame-relatedness
> of the instructions is fine.

This looks like the most straightforward approach, so I'd give it a try and 
post a patch along these lines on the gcc-patches@ list (you can CC me on it).
If other people come up with a better idea, we can further discuss from there.

-- 
Eric Botcazou