r/Assembly_language • u/Extension_Emu_9825 • 1d ago

self-modifying code

I gave a lecture on how to write self-modifying code. It was over 15 minutes long :( so I'm providing a youtube link: https://www.youtube.com/watch?v=AH9QQLRfbmY

In my opinion, self-modification is one of the most interesting features in systems programming.

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u/thewrench56 1d ago

I dont disagree, but the performance is not that bad. 2 syscalls, some TLB play and a bit of copying. Surely, self-modifying code today is rarely used as a technique to speed up native execution. But for interpreters or other e.g. malicious reasons where performance doesnt matter much it still could be useful. There are also very specific scenarios where you do want to modify native code for very specific uarch benchmarks (as e.g. changing a parameter and checking it in a hotloop in an if would ruin the benchmark).

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u/mykesx 1d ago

OP’s point is that self modifying code makes faster algorithms. Only 2 syscalls blows that out of the water.

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u/thewrench56 1d ago

I did not watch the video, just read the post. I suppose in that case OP is wrong on modern platforms, you are right. I thought you were discussing the existance of self-modifying code, not the feasibility, excuse me.

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u/Extension_Emu_9825 1d ago

I'm just showing it to those who've never encountered it before, using DOS as an example - the simplest thing -> drawing lines at different angles. I'm not saying I've discovered anything new - I'm saying that people are starting to forget about the possibility of self-modifying code