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

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

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

--- Comment #23 from Jiu Fu Guo <guojiufu at gcc dot gnu.org> ---
/* Simplify ((t + -N*M) / N + M) -> t / N: (t + -C) >> N + (C>>N) ==> t >> N */
(for div (trunc_div exact_div)
 (simplify
  (plus (rshift (plus @0 INTEGER_CST@1) INTEGER_CST@2) INTEGER_CST@3)
  (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type) &&
       (wi::to_wide (@3) << wi::to_wide (@2)) == -wi::to_wide (@1))
   (if (TYPE_OVERFLOW_UNDEFINED (type))
    (div @0 @2)
#if GIMPLE
    (with
     {
       bool overflowed = true;
       value_range vr0;
       if (get_range_query (cfun)->range_of_expr (vr0, @0)
           && !vr0.varying_p () && !vr0.undefined_p ())
         {
           wide_int wmin0 = vr0.lower_bound ();
           wide_int wmax0 = vr0.upper_bound ();
           wide_int w1 = -wi::to_wide (@1);
           wi::overflow_type min_ovf, max_ovf;
           wi::sub (wmin0, w1, TYPE_SIGN (type), &min_ovf);
           wi::sub (wmax0, w1, TYPE_SIGN (type), &max_ovf);
           if (min_ovf == wi::OVF_NONE && max_ovf == wi::OVF_NONE)
             overflowed = false;
         }
     }
    (if (!overflowed)
     (rshift @0 @2)))
#endif
   ))))

Got one match for the case.
Checking if it is safe(condition) or how to support other forms:
signed type, negative N, non-power2 N, negative M ...