What in the holy hell is a pointer to function and function pointer.I guess they have a purpose, I hate their existence. It's solely because it is complicated

They aren’t so bad.

They're necessary for implementing callbacks, closures, vtables, coroutines, threads, runtime incrementally optimized functions (think JIT compilers), and other low level hackery.

I mean it's literally just like any other pointer.

What is a function pointer?
`jmp (eax)`

Any function is basically just a pointer to a region in memory where the function starts. That's it.

Pointers are essentially as complicated as you make them to be while really being a very simple concept.

@RememberMe do you know resources for learning about jit?

@iiii I use LLVM for stuff sometimes. Found that the standard tutorial (kaleidoscope) includes using the inbuilt JIT compiler (it's literally like 5 extra lines or something). You can play around with that. I also built a basic lisp interpreter that had an incredibly crap JIT compiler. Didn't use any resource as such, you just write your compiled binary output to a page (I just used clang to compile the C output of my lisp compiler...like I said, crap), mark it as executable, and jump to that pointer, literally all there is to it.

I believe LuaJIT is a relatively simple thing you can look at too.

@RememberMe I've heard LLVM being pretty slow to compile on the fly 🤔

@iiii yeah I don't think anyone uses LLVM for JIT, it's just there for convenience in case you want to hot reload and stuff. A good JIT compiler is intimately tied to a good runtime system, and LLVM does not provide a runtime system, that's not in its scope.

Making a good one is really really tricky. I'd say JavaScript engines do it best, along with JVMs and the CLR. Not something I know much about though.

You people won't let me rant peacefully 😂. I know their importance, it's just a rant. That's what I told in my initial rant. I guess I am that guy who just complains about everything, no matter what 🥱

Your program is just data that happens to correspond to CPU instructions.

A pointer to a function is just that - a pointer to some of that data. Like a pointer to a variable or whatnot.

What's confusing about it?

@RememberMe Definitely use LLVM for JIT. Check out Terra - we use it there for JIT.

@junon I meant using it as is. LLVM's JIT isn't terribly fast from what I remember, and you have to build tracing and on-the-fly optimization etc. on top of it anyway, that's the actually hard part of JIT. I could imagine it being used just for the compile step.

@RememberMe What do you mean used "as-is"?