Check array indices in object_address_invariant_in_loop_p (PR 84357)

Check array indices in object_address_invariant_in_loop_p (PR 84357)

object_address_invariant_in_loop_p ignored ARRAY_REF indices on
the basis that:

	  /* Index of the ARRAY_REF was zeroed in analyze_indices, thus we only
	     need to check the stride and the lower bound of the reference.  */

That was true back in 2007 when the code was added:

static void
dr_analyze_indices (struct data_reference *dr, struct loop *nest)
{
  [...]
  while (handled_component_p (aref))
    {
      if (TREE_CODE (aref) == ARRAY_REF)
        {
          op = TREE_OPERAND (aref, 1);
          access_fn = analyze_scalar_evolution (loop, op);
          access_fn = resolve_mixers (nest, access_fn);
          VEC_safe_push (tree, heap, access_fns, access_fn);

          TREE_OPERAND (aref, 1) = build_int_cst (TREE_TYPE (op), 0);
        }

      aref = TREE_OPERAND (aref, 0);
    }

but the assignment was removed a few years ago.  We were therefore
treating "two->arr[i]" and "three->arr[i]" as loop invariant.

2018-02-14  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	PR tree-optimization/84357
	* tree-data-ref.c (object_address_invariant_in_loop_p): Check
	operand 1 of an ARRAY_REF too.

gcc/testsuite/
	PR tree-optimization/84357
	* gcc.dg/vect/pr84357.c: New test.

From-SVN: r257657