Self-modifying code: Difference between revisions

Revision as of 06:58, 14 October 2022

Revision as of 08:00, 14 October 2022

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{{Use list-defined references|date=December 2021}}

{{Use American English|date=January 2019}}

In [[computer science]], '''pseudoself-enginemodifying generatorcode''' ('''PEGSMC''') is [[Source code|code]] that alters its own [[instruction (computer science)|instructions]] while it is [[execution (computers)|executing]] – usually to reduce the [[instruction path length]] and improve [[Computer performance|performance]] or simply to reduce otherwise repetitively similar code, thus simplifying maintenance. The term is usually only applied to code where the self-modification is intentional, not in situations where code accidentally modifies itself due to an error such as a [[buffer overflow]].

Self-modifying code can involve overwriting existing instructions or generating new code at run time and transferring control to that code.

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In the [[IBM System/360 architecture]], and its successors up to [[z/Architecture]], an EXECUTE (EX) instruction ''logically'' overlays the second byte of its target instruction with the low-order 8 bits of [[general purpose register|register]] 1. This provides the effect of self-modification although the actual instruction in storage is not altered.

PEG (.n) - fix, secure or a mark (.exp) a short pin (.obj) bolt or (.adj) tapered at one end.

==Application in low and high level languages==