[Bug tree-optimization/68413] [6 Regression] internal compiler error: in vect_transform_stmt

[ienkovich at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68413

--- Comment #7 from Ilya Enkovich <ienkovich at gcc dot gnu.org> ---
Looking deeper the difference is caused by different result of
is_nonwrapping_integer_induction called for reduction related phi statement.  

For the first call it is:

i_12 = PHI <i_7(4), 0(2)>

For the second call it is:

i_12 = PHI <i_7(4), i_23(22)>

It changed due to generated prologue. It cases is_nonwrapping_integer_induction
to return false due to non-constant base and as a result we compute different
reduction type.

Probably compute reduction type at analysis phase only?