llvm dev - Jun 2008 - [LLVMdev] ExecutionEngine::create returns 0

> Now to compare it in detail with the much smaller program I've got and
> maybe I'll figure out what's wrong with my call to
> ExecutionEngine::create.
That call is perfectly valid, actually. It works for me when linked with:

g++ -o b b.o `llvm-config --ldflags` `llvm-config --libs engine jit`

Cheers,
-Mahadevan.

On Tue, 10 Jun 2008 07:07:35 +0530, Mahadevan R wrote:
>> Now to compare it in detail with the much smaller program I've got
and
>> maybe I'll figure out what's wrong with my call to
>> ExecutionEngine::create.
> 
> That call is perfectly valid, actually. It works for me when linked
> with:
> 
> g++ -o b b.o `llvm-config --ldflags` `llvm-config --libs engine jit`
> 
> Cheers,
> -Mahadevan.
Thanks.  It's compiling and executing now.

The story appears to be this:

  llvm::ExecutionEngine::create requires particular libraries (presumably 
those that involve execution, JIT code generation, or interpretation) to 
be linked into the executable (the executable that contains the call to 
llvm::ExecutionEngine::create), or else it returns NULL.  However, 
llvm::ExecutionEngine::create does not itself contains references to 
entry-points that would cause the necessary libraries to be sought by the 
linker, so no linker failure results.

Would it be possible to include this information in the documentation for 
llvm::ExecutionEngine::create?

-- hendrik

Hendrik Boom-2 wrote:
> 
> On Tue, 10 Jun 2008 07:07:35 +0530, Mahadevan R wrote:
> 
>>> Now to compare it in detail with the much smaller program I've
got and
>>> maybe I'll figure out what's wrong with my call to
>>> ExecutionEngine::create.
>> 
>> That call is perfectly valid, actually. It works for me when linked
>> with:
>> 
>> g++ -o b b.o `llvm-config --ldflags` `llvm-config --libs engine jit`
>> 
>> Cheers,
>> -Mahadevan.
> 
> Thanks.  It's compiling and executing now.
> 
> The story appears to be this:
> 
>   llvm::ExecutionEngine::create requires particular libraries (presumably 
> those that involve execution, JIT code generation, or interpretation) to 
> be linked into the executable (the executable that contains the call to 
> llvm::ExecutionEngine::create), or else it returns NULL.  However, 
> llvm::ExecutionEngine::create does not itself contains references to 
> entry-points that would cause the necessary libraries to be sought by the 
> linker, so no linker failure results.
> 
> Would it be possible to include this information in the documentation for 
> llvm::ExecutionEngine::create?
> 
> -- hendrik
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> 
> 
I am using llvm 2.6 and I am getting the same error. I tried using
llvm-config with flags '--libs core engine jit native'. But
ExecutionEngine
returns NULL. I even tried including the JIT.h. No luck there too.

Here is my code listing:
        llvm::ExecutionEngine* ee  = llvm::ExecutionEngine::create(mModule);
	llvm::Function* func = ee->FindFunctionNamed("main");
	typedef void (*PFN)();
	PFN pfn = reinterpret_cast<PFN> (ee->getPointerToFunction(func));
	pfn();
	delete ee;

thanks, 
subramanyam
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