1. A method of identifying deprecated routines invoked by a software application implementing subtype polymorphism, said method comprising: receiving software instructions constituting said software application; identifying, in said software application, a set of polymorphic data types, a plurality of variables of said set of polymorphic data types and a corresponding set of assignments for each of said plurality of variables; finding, in said software application, a first set of instructions, with each of said first set of instructions containing an invocation of a routine associated with one of said plurality of variables; determining, based on said corresponding set of assignments, a first plurality of routines that would be caused to be invoked for the invocation specified in said first set of instructions; ascertaining a first set of the routines of said first plurality of routines which are deprecated; and generating a report indicating the instructions causing invocation of said first set of routines, wherein said identifying and said finding are performed by examination of said software instructions, without having to execute said software instructions.