[Bug tree-optimization/64183] [5.0 Regression] Complete unroll doesn't happen for a while-loop

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64183

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Which is

(instantiate_scev
  (instantiate_below = 10)
  (evolution_loop = 2)
  (chrec = (24 - (unsigned int) prephitmp_36) / 8)
  (res = (24 - (unsigned int) prephitmp_36) / 8))
  (set_nb_iterations_in_loop = scev_not_known))

vs.

(instantiate_scev
  (instantiate_below = 4)
  (evolution_loop = 1)
  (chrec = (24 - (unsigned int) bits.0_8) / 8)
  (res = (24 - (unsigned int) bits.0_8) / 8))
  (set_nb_iterations_in_loop = (unsigned int) bits.0_8 + 1 <= 25 ? (24 -
(unsigned int) bits.0_8) / 8 : 0))

with otherwise exactly the same scalar evolution analysis...