[Micoloth]

I’ll take advantage of this comment to ask the tangential question: Where can i learn how llvm “compilation” works in Julia?

I know code is only supposed to be JIT’ed and then executed by the runtime (that’s why PackageCompiler exists), but still I’d like to know more about how it works..

Like, if i write a simple pure function in Julia and call code_llvm on it… How “standalone” is the llvm code (if that is even a thing)? When does GC get called? How exactly does the generated code depend on the runtime?

Is there any good explanation of this?

[staticfloat]

To add to Keno's sibling comment, Julia, as a JIT compiler, essentially creates large chunks of standalone, "static" code, and runs those as much as it can, breaking out into the "dynamic" runtime when it has reached the limits of type inference or for some other reason needs to return to the runtime to perform dynamic dispatch etc... in these instances, we break out of the standalone code and start using the runtime to do things like determine where to jump next (or whether to compile another chunk of static code and jump to that). Note that these chunks of static code can be both smaller or larger than a function, it all depends on what Julia can compile in one go without needing to break out into the dynamic environment.

[KenoFischer]

> Like, if i write a simple pure function in Julia and call code_llvm on it… How “standalone” is the llvm code (if that is even a thing)? When does GC get called? How exactly does the generated code depend on the runtime?

It's standalone unless there's explicit calls to the runtime in it. The most common runtime support is probably heap allocation, so if you see a `jl_alloc_obj` in there, that gets lowered to runtime calls eventually. GC gets called during allocation if the runtime thinks there's been enough garbage generated to have a collection be worth it.