[Bug tree-optimization/79721] Scalar evolution introduces signed overflow

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79721

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 40844
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40844&action=edit
untested patch

After this patch re-writing to unsigned in final value replacement shouldn't be
needed anymore.