[LLVMdev] using external functions from llvm

[Alec Benzer]

> I'm afraid that you might be utterly confused about how to use LLVM.

Er, I don't think so? I think I was mostly just confused about interfacing
with external functions, since whoever wrote that blog post (
http://www.gearleaf.com/blog/post/44) didn't seem to know what he was
talking about (or he was doing stuff that once worked but now doesn't? I
don't know). If you glance at that post I think you'll understand why I was
doing what I was doing.

anyway, I think I get it now, what I was trying to do seems to be working
how I expect it to.

On Thu, Aug 19, 2010 at 8:55 PM, Óscar Fuentes <ofv at wanadoo.es> wrote:

> The following message is a courtesy copy of an article
> that has been posted to gmane.comp.compilers.llvm.devel as well.
>
> Alec Benzer <alecbenzer at gmail.com> writes:
>
> > Ok, so calling lle_X_FUNCTIONNAME instead of FUNCTIONNAME works (is there
> > any reason the post used the lle_X_ prefix other than convention? was it
> > once possible to call external functions as I was originally trying, or,
> why
> > did the blog post think it was possible?)
>
> AFAIK you can name the function as you please (with some reasonable
> restrictions on the character set, etc)
>
> > I'm now running into trouble when trying to access arguments however.
> > printing args.size() from the function yields 12105250188025543488. The
> > generated call to it looks like:
> >
> > %object_tmp = call %object_structure* @lle_X_create_number_object(double
> > 5.000000e+00) ; <%object_structure*> [#uses=1]
>
> You are calling a function that takes a single argument of type
> `double'. But on a previous post you showed the function with this
> signature:
>
> llvm::GenericValue
> lle_X_create_number_object(llvm::FunctionType* ft,
>                           const std::vector<llvm::GenericValue>& args)
>
> so as the execution enters the function above from your call, the stack
> can be considered corrupt. Also, the return type of the `call' might not
> be right (it depends on the ABI of your platform.)
>
> It is strange to generate GenericValue's from JITted code. Are you doing
> some kind of meta-interpreter? I'm afraid that you might be utterly
> confused about how to use LLVM.
>
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