[llvm-dev] llvm interpreter does not find function defined by addGlobalMapping

[via llvm-dev]

 Hi Lang,

> What happens if you set the data layout on pModule before creating the
> engine?

The output of pExecutionEngine->getDataLayout().getStringRepresentation() is an empty string if I do not set the layout on pModule before creating the interpreter engine. If I set the layout before, the output is the specified layout. But unfortunately, the error is still there.

Markus

> 
> - Lang.
> 
> On Mon, Sep 19, 2016 at 5:34 AM, via llvm-dev <llvm-dev at lists.llvm.org>
> wrote:
> 
> > Hi,
> >
> > I want to use a function defined in c(++)-code from code generated by
> > llvm. For this I use ExecutionEngine.addGlobalMapping(). I started with
> > the JIT execution engine and everything worked, then I switched to the
> > interpreter engine and it stopped working, but only if compiled on a
> Linux
> > system. More precisely it works if I use
> >
> >     llvm 3.8.1 + gcc (Linux) + JIT
> >     llvm 3.8.0 + mingw-gcc (Windows) + JIT
> >     llvm 3.8.0 + mingw-gcc (Windows) + Interpreter
> >
> > But it does not work for llvm 3.8.1 + gcc (Linux) + Interpreter. In that
> > case I get the error message "LLVM ERROR: Tried to execute an unknown
> > external function: testFunction." Am I using
> ExecutionEngine.addGlobalMapping()
> > in the wrong way, even it works in three out of four scenarios?
> >
> > #include <llvm/Support/TargetSelect.h>
> > #include <llvm/Analysis/Passes.h>
> > #include <llvm/Transforms/Scalar.h>
> > #include <llvm/Transforms/IPO/PassManagerBuilder.h>
> > #include <llvm/Transforms/IPO.h>
> > #include <llvm/IR/Verifier.h>
> > #include <llvm/ExecutionEngine/ExecutionEngine.h>
> > #include <llvm/ExecutionEngine/Interpreter.h>
> > #include <llvm/ExecutionEngine/MCJIT.h>
> > #include <llvm/ExecutionEngine/GenericValue.h>
> > #include <llvm/IR/LegacyPassManager.h>
> > #include <llvm/IR/IRBuilder.h>
> >
> > extern "C" double testFunction(){
> >   return 42.0;
> > }
> >
> > int main() {
> >   // initialization needed for JIT
> >   llvm::InitializeNativeTarget();
> >   llvm::InitializeNativeTargetAsmPrinter();
> >   llvm::InitializeNativeTargetAsmParser();
> >
> >   llvm::LLVMContext &context(llvm::getGlobalContext());
> >   llvm::Module *pModule = new llvm::Module("a module", context);
> >
> >   // Here the EngineKind-flag decides if JIT or interpreter is used.
> >   auto pExecutionEngine = llvm::EngineBuilder(std::
> > unique_ptr<llvm::Module>(pModule)
> >     ).setEngineKind(llvm::EngineKind::Interpreter).create();
> >   pModule->setDataLayout(pExecutionEngine->getDataLayout());
> >
> >   // declaration of the c function.
> >   std::vector<llvm::Type *> noArgTypes;
> >   llvm::FunctionType* ft = llvm::FunctionType::get(llvm::
> > Type::getDoubleTy(context),noArgTypes, false);
> >   auto pFunction = llvm::Function::Create(ft,
> llvm::Function::ExternalLinkage,
> > "testFunction",pModule);
> >   pExecutionEngine->addGlobalMapping(pFunction,reinterpret_cast<void*>(&
> > testFunction));
> >
> >   // generation of llvm code
> >   auto pBlock = llvm::BasicBlock::Create(context, "evaluation");
> >   llvm::IRBuilder<> builder(context);
> >   builder.SetInsertPoint(pBlock);
> >
> >   // code for call of the c function.
> >   auto pFunction2 = pModule->getFunction("testFunction");
> >   auto temp = builder.CreateCall(pFunction2, std::vector<llvm::Value*>(),
> > "calltmp");
> >   builder.CreateRet(temp);
> >
> >   // generation of the llvm function calling the c function
> >   llvm::FunctionType* ftWrapper = llvm::FunctionType::get(llvm::
> > Type::getDoubleTy(context),noArgTypes, false);
> >   auto pWrapperFunction = llvm::Function::Create(ftWrapper,
> > llvm::Function::ExternalLinkage, "AFunction",pModule);
> >   pWrapperFunction->getBasicBlockList().push_back(pBlock);
> >
> >   // calling the generated llvm function
> >   pExecutionEngine->finalizeObject();
> >   pExecutionEngine->runFunction(pWrapperFunction,std::vector<
> > llvm::GenericValue>());
> > }
> >
> > Thanks for any help,
> > Markus
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >
>