Comment by pbasista
25 days ago
> How good are you at writing assembly?
How is that relevant to the topic of this discussion?
Compilation from higher order languages to the machine code is deterministic. It is sufficient to review and well-test the tool which does the translation. Given the same input, the output will always be the same.
Transformation of a natural language prompt to code by an AI tool is non-deterministic. The outputs will vary between runs. Therefore, it is always necessary to verify them.
That is the difference.
Compilation is not deterministic, see JITs and GCs. What is deterministic is the resulting program output, but not its performance. So with compilers, we traded away the determinism over performance in exchange for ease of programming.
With LLMs, we are trading away the determinism of the program output as well, in exchange for even more easier programming. Is it a good or bad thing? There are ways to mitigate the problem, just like there are with compilers.
You could argue the determinism of the program output was never really there, because the specification at the high enough level was always unclear. So we are not really losing that much, just accepting more messy reality.
Then the only question remains, can these computer programs (LLMs) do a better job (and where) than a SW developer, who is supposed to translate unclear specifications into a formal language (source code). It happened with compilers - eventually they got better than all of assembler programmers. Same happened to chess players.
> Compilation is not deterministic, see JITs and GCs. What is deterministic is the resulting program output, but not its performance.
Does JIT compiles some other program code instead of the one being run? Does it produce bytecodes for a differenr VM? Does it tries to compile parts of the program that have not been executed or aren’t going to be?
Does GC destroy objects being in use? Does it ignores instances and memory that has been properly released?
JITs and GC are deterministic algorithms, you can predict its behavior by just reading their code. LLM tooling involves an actual random generator for its output.
> Does JIT compiles some other program code instead of the one being run? Does it produce bytecodes for a different VM? Does it tries to compile parts of the program that have not been executed or aren’t going to be?
Sure, but the same is true for LLMs - the lead models no longer make trivial mistakes like answering "What is the capital of France?" wrong.
> JITs and GC are deterministic algorithms, you can predict its behavior by just reading their code.
On large enough systems, you can't, just like it's difficult to predict weather. Determinism has little to do with it. At work, I have just witnessed a bug in JIT (it seems to have been fixed in OpenJDK 25). It inlined a wrong method. We weren't able to reproduce the error conditions without a private customer dataset.
And the fact is, historically, there have been many bugs in compilers, or they have been bad at their job, writing performant programs. The output (resulting program) of a good compiler is difficult to understand (because it is written to be efficient). LLMs (for the programming use case) are different quantitatively, not qualitatively.
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> Compilation from higher order languages to the machine code is deterministic. but that's not the analogy. there are problems that you can solve better if you can go deeper in the stack, and they can have different solutions.