retrieved and execution then carries on with the current instruction stream which will analyse the returned data block or the data returned in the register or registers since the conventional cpu already has an instruction fetch unit 110 and a decode unit 140 for normal execution of program instructions there are few or no additional hardware elements required the performance of the u2018 analysethis u2019 instruction within the cpu instruction set is not very important because the set of instructions currently being carried out in software to figure out what an instruction does is complex thus the u2018 analysethis u2019 instruction doesn 39 t have to be performed very quickly to still be much better than implementing it in software the method of fig2 of analysis of a computer program instruction allows a code analyzer program such as a tracing program debugger or similar to analyse instructions which it is proposed to replace with a trap i e a program interrupt or by a call to a debug program that analysis may conclude that the instruction is one that can be replaced without any harm that is without affecting the operation of the program up to the point where it is reached or subsequently the code analyzer program does not have to manually decode exactly what.