Need help about LLVM build coroutine

[Dakota]

On Saturday, 2 March 2024 at 12:32:32 UTC, Richard (Rikki) Andrew 
Cattermole wrote:
> From what I'm reading of the documentation, it looks like you 
> have to work at the IR level to declare a coroutine.
>
> This isn't something you can do with only intrinsics in library 
> code.
>
> https://llvm.org/docs/Coroutines.html#introduction
>
> Take note of the function attribute ``presplitcoroutine`` under 
> coroutine representation.
>
> https://llvm.org/docs/Coroutines.html#coroutine-representation

Thanks for the tips. I dont understand LLVM IR.  I want to create 
a LLIR function which accept 2 parameters,  first one is a 
pointer of coroutine function entry, the other is a pointer to a 
struct look like this:

```d
struct coroutine_object {
     void* coro_handler;
     void* core_argv;
     size_t core_argc;
}
```


this llvm IR should create one new coroutine, and save the 
handler into arg2.coro_handler, then start enter the coroutine to 
execute.


I use chatGPT get this code.  any one can help me fix it and 
export to `extern(C)`

```ir

define void @start_coroutine(i8* %func_ptr, i8** 
%coro_handle_ptr) {
entry:
   %func = bitcast i8* %func_ptr to void (i8*)*

   %coro_begin = call i8* @llvm.coro.begin(token none, i8* null, 
i8* null)

   store i8* %coro_begin, i8** %coro_handle_ptr

   call void @llvm.coro.alloc(i8* %coro_begin, i8* bitcast (void 
(i8*)* @coro_func to i8*))

   call void @llvm.coro.init(token none, i8* %coro_begin, i8* 
%coro_begin)

   call void @llvm.coro.save(i8* %coro_begin, i8** null)

   call void @llvm.coro.resume(i8* %coro_begin)

   ret void
}

declare token @llvm.coro.begin(token, i8*, i8*)
declare void @llvm.coro.alloc(i8*, i8*)
declare void @llvm.coro.init(token, i8*, i8*)
declare void @llvm.coro.save(i8*, i8**)
declare void @llvm.coro.resume(i8*)
```

to build it use :

```sh
llvm-as -o coro.bc coro.ll
llvm-ar rcs libcoro.a coro.bc
```