llvm dev - Sep 2010 - [LLVMdev] ExecutionEngine::create returns 0

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
> 
> _______________________________________________
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> 
> 
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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> 
> 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;
More information would be helpful, if you have a program that someone else can
compile or take a look at we might be able to help.

That said, 2.6 is pretty old at this point and I'm really only willing to
look at failures with ToT. The HowToUseJIT example compiles and links just fine
on ToT for me.


-eric

On Sep 28, 2010, at 1:53 AM, Subramanyam P.U.R. wrote:
> I am using Fedora 10 and I installed LLVM2.6 from binaries. I use gcc
front-end(not Clang). Do I need to install something else, to be able to add JIT
support?
> 
I don't know, I don't package it.
> I am able to compile HowToUseJIT example. The compilation command is
> g++ -g -rdynamic toy.cpp `llvm-config --cppflags --ldflags --libs core jit
native` -O3 -o toy
> 
> But I am getting segmentation fault because of the NULL returned by
ExecutionEngine::create(Module*) method.
> 
Not surprising since you're dereferencing a NULL pointer.
> Here is the error I get when I run HowToUseJIT example
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x080b02f6 in llvm::ExecutionEngine::getTargetData () at
/home/subbu/llvm/install/include/llvm/ExecutionEngine/ExecutionEngine.h:167
> 167	  const TargetData *getTargetData() const { return TD; }
> 
Is that using 2.6 or something newer? My guess is that, of course, you don't
have a target data.  You'll need to debug why you can't seem to create
one for your host.  That said, if you can't get it to work with the 2.8
branch let me know.

-eric