[Bug tree-optimization/57275] [4.9 Regression] Error in data dependence analysis during gather vectorization

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57275

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
There is:

  /* Independent data accesses.  */
  if (DDR_ARE_DEPENDENT (ddr) == chrec_known)
    return false;

  if (dra == drb
      || (DR_IS_READ (dra) && DR_IS_READ (drb)))
    return false;

a few lines before this.