US Patent 10445216 Debugging program code at instruction level through emulation

Methods and systems are disclosed for debugging program code at instruction level by emulating an epilog. Issues with retrieving values that a caller function has stored in non-volatile registers before calling a callee function are addressed at the instruction code level by through emulation. The epilog of the callee function may be emulated after copying a computing environment of the target program code from a target system to an emulation system. When the debugged code does not include an epilog, values that a caller function stored before calling a callee function in non-volatile registers may be retrieved by emulating the calling function forward from the breakpoint.