Even though instanceof check (and reflective Class.isInstance call) narrows operand's type, sharpened type information is not explicitly materialized in the IR.

There's a SubTypeCheck node present, but it doesn't cover all the cases.

The difference can be illustrated with the following simple cases:

   class A { void m() {} }
   class B extends A { void m() {} }

    void testInstanceOf(A obj) {
        if (obj instanceof B) {
            obj.m();
        }
    }

167 11 b InstanceOf::testInstanceOf (12 bytes)
                            @ 8 InstanceOf$A::m (0 bytes) failed to inline: virtual call

vs

    void testInstanceOfCast(A obj) {
        if (obj instanceof B) {
            B b = (B)obj;
            b.m();
        }
    }

173 12 b InstanceOf::testInstanceOfCast (17 bytes)
                            @ 13 InstanceOf$B::m (1 bytes) inline (hot)