[LLVMdev] Using a function from another module

[Jeffrey Yasskin]

The JIT tries to handle this in some cases
(http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/ExecutionEngine.cpp?annotate=92771#l942),
but doesn't handle it for functions. There aren't any tests, so I'm
not surprised it's broken.

The JIT would be simpler if we just dropped multiple-module support
and asked people to link their modules together before trying to JIT
them.  Is there a reason you can't do that?

If there is, could you write a test for
http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ExecutionEngine/JIT/
that exercises the behavior you want, and file a bug with it attached?
I'm not likely to actually implement that any time soon, but having a
bug with a test will make it easier for someone else to pick it up.

Thanks,
Jeffrey

On Fri, Jan 8, 2010 at 4:49 PM, Michael Muller <mmuller at enduden.com> wrote:
>
> Hi all,
>
> I'm trying to use a function defined in one LLVM module from another module
> (in the JIT) but for some reason it's not working out.  My sequence of
> activity is roughly like this:
>
>  1) Create moduleA
>  2) Create moduleB with "func()"
>  3) execEng = ExecutionEngine::create(
>         new ExistingModuleProvider(moduleB));
>  4) execute "func()" (this works fine)
>  4) add "func()" to moduleA as a declaration (no code blocks) with External
>     linkage.
>  5) execEng->addModuleProvider(new ExistingModuleProvider(moduleA));
>  6) run a function in moduleA that calls "func()"
>
> I get:
>  LLVM ERROR: Program used external function 'func' which could not be resolved!
>
> I'm guessing I'm either going about this wrong or missing something.  Can
> anyone offer me some insight?
>
> =============================================================================
> michaelMuller = mmuller at enduden.com | http://www.mindhog.net/~mmuller
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