[Bug tree-optimization/108757] We do not simplify (a - (N*M)) / N + M -> a / N

[segher at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108757

--- Comment #6 from Segher Boessenkool <segher at gcc dot gnu.org> ---
No?  Take a=59 as counterexample:

(a - (N*M)) / N + M = (59 - 2*30)/30 + 2 = ~0UL/30 + 2

but

a / N = 59/30 = 1

Integer division in C is division towards zero, almost no normal algebraic
simplifications apply there.