Protecting computer code against ROP attacks

A method, computer product and computerized system, the method comprising: obtaining computer code, wherein the computer code is comprised of code blocks arranged in a first order and providing a functionality, wherein each code block of the code blocks comprises one or more program instructions; determining, by a processor, one or more constraints on reordering the code blocks in a second order, such that a second computer code comprising the code blocks arranged in the second order, when executed, provides the functionality; and providing the constraints to an automatic solver for determining the second order.