One or more processors receive a breakpoint. The breakpoint is paired with a resume point. One or more processors execute a set of machine instructions on a virtual processor model. One or more processors halt execution of the set of machine instructions on the virtual processor model at the breakpoint. One or more processors execute a fragment of a program instruction on a physical processor. The fragment is logically equivalent to the set of machine instructions between the breakpoint and the resume point. One or more processors load a processed result into the virtual processor model. The processed result results from executing the fragment on the physical processor. One or more processors resume the execution of the set of machine instructions on the virtual processor model at the resume point.