PR tree-optimization/23320

        * tree-data-ref.c (base_addr_differ_p): Add comment. Check
        data-refs' types instead of base object nullness. Add check for
        pointer type data-refs before first location comparison. Remove
        assert.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@103076 138bc75d-0d04-0410-961f-82ee72b054a4