[Bug rtl-optimization/64081] [5/6/7 Regression] r217827 prevents RTL loop unroll

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64081

--- Comment #56 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Yes, and a function that computes a "more permissive" version should
not have "simple_loop" in its name, it is very misleading.  Reusing
existing functions to do something different may seem attractive at
first ("less churn") but is more expensive in the long run; we have
spent more time on this PR alone than doing things properly would have
taken in the first place.