Indirect addressing, including memory indirect addressing, which takes a base address (register), an index (register), a size (immediate), two offsets (immediate), and an address stored in memory somewhere.

You could, in one single instruction,

  struct B {
    int x, y, z;
  };
  struct A {
    int a, b, c;
    struct B *ptr;
  };

  void func(struct A *array, int i) {
    array[i].ptr->z = 3;
  }

Unless I am remembering how it works incorrectly.