[LLVMdev] Interpreter with multiple modules.

Garrison Venn gvenn.cfe.dev at gmail.com
Wed Feb 3 07:29:10 PST 2010

Hi James,

> This is interesting. I've just implemented dynamic loading of bitcode modules into lli for my project. I did this by hacking lli using the Linker class. Is ExecutionEngine::addGlobalMapping() preferred for this purpose?

I'm not sure about the preferred way, but at least for the JIT, here is an email from Jeffrey 
concerning a previous thread. The issue in that thread was solved via use of 
ExecutionEngine::addGlobalMapping(...). I don't know if the inability of the JIT or
interpreter systems to automatically search in other modules is by design or not.


On Jan 11, 2010, at 14:39, Jeffrey Yasskin wrote:

> 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
>> -----------------------------------------------------------------------------
>> We are the music-makers, and we are the dreamers of dreams
>>  - Arthur O'Shaughnessy
>> =============================================================================
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