[Bug rtl-optimization/68636] unnecessary unaligned load on mips o32

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68636

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
And we also return true thus "known" which will override the type alignment
present on the MEM_REF:

      /* When EXP is an actual memory reference then we can use
         TYPE_ALIGN of a pointer indirection to derive alignment.
         Do so only if get_pointer_alignment_1 did not reveal absolute
         alignment knowledge and if using that alignment would
         improve the situation.  */
      if (!addr_p && !known_alignment
          && TYPE_ALIGN (TREE_TYPE (exp)) > align)
        align = TYPE_ALIGN (TREE_TYPE (exp));