[Bug tree-optimization/114485] [13/14 Regression] Wrong code with -O3 -march=rv64gcv on riscv or `-O3 -march=armv9-a` for aarch64

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114485

--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
  /* Init_expr will be update by vect_update_ivs_after_vectorizer,
     if niters or vf is unkown:
     For shift, when shift mount >= precision, there would be UD.
     For mult, don't known how to generate
     init_expr * pow (step, niters) for variable niters.
     For neg, it should be ok, since niters of vectorized main loop
     will always be multiple of 2.

well, for partial vectors that's of course not true.