[Bug tree-optimization/82450] loop flattening should be done

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82450

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
We once had a very aggressive pass to do this as part of graphite transforms,
it's on the GCC 4.7 branch.