&& ptr_difference_const (arg0, arg1, &diff))
return build_int_cst_type (type, diff);
}
-
+
+ /* Fold &a[i] - &a[j] to i-j. */
+ if (TREE_CODE (arg0) == ADDR_EXPR
+ && TREE_CODE (TREE_OPERAND (arg0, 0)) == ARRAY_REF
+ && TREE_CODE (arg1) == ADDR_EXPR
+ && TREE_CODE (TREE_OPERAND (arg1, 0)) == ARRAY_REF)
+ {
+ tree aref0 = TREE_OPERAND (arg0, 0);
+ tree aref1 = TREE_OPERAND (arg1, 0);
+ if (operand_equal_p (TREE_OPERAND (aref0, 0),
+ TREE_OPERAND (aref1, 0), 0))
+ {
+ tree op0 = fold_convert (type, TREE_OPERAND (aref0, 1));
+ tree op1 = fold_convert (type, TREE_OPERAND (aref1, 1));
+ tree esz = array_ref_element_size (aref0);
+ tree diff = build2 (MINUS_EXPR, type, op0, op1);
+ return fold_build2 (MULT_EXPR, type, diff,
+ fold_convert (type, esz));
+
+ }
+ }
+
/* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step
of the array. Loop optimizer sometimes produce this type of
expressions. */