[Bug tree-optimization/69720] [4.9/5/6 Regression] wrong code at -O3 on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69720

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
vect_finalize_reduction:
...

  /* 2.5 Adjust the final result by the initial value of the reduction
         variable. (When such adjustment is not needed, then
         'adjustment_def' is zero).  For example, if code is PLUS we create:
         new_temp = loop_exit_def + adjustment_def  */

  if (adjustment_def)
    {
      gcc_assert (!slp_reduc);

misses support for ncopies > 1.

Bah, stupid spaghetti in this function.