Call LLVM Jit from c program

Question

I have generated a bc file with the online compiler on llvm.org, and I would like to know if it is possible to load this bc file from a c or c++ program, execute the IR in the bc file with the llvm jit (programmatically in the c program), and get the results.

How can I accomplish this?

Answer 1

Here's some working code based on Nathan Howell's:

#include <string>
#include <memory>
#include <iostream>

#include <llvm/LLVMContext.h>
#include <llvm/Target/TargetSelect.h>
#include <llvm/Bitcode/ReaderWriter.h>
#include <llvm/ExecutionEngine/ExecutionEngine.h>
#include <llvm/ModuleProvider.h>
#include <llvm/Support/MemoryBuffer.h>
#include <llvm/ExecutionEngine/JIT.h>

using namespace std;
using namespace llvm;

int main()
{
    InitializeNativeTarget();
    llvm_start_multithreaded();
    LLVMContext context;
    string error;
    Module *m = ParseBitcodeFile(MemoryBuffer::getFile("tst.bc"), context, &error);
    ExecutionEngine *ee = ExecutionEngine::create(m);

    Function* func = ee->FindFunctionNamed("main");

    typedef void (*PFN)();
    PFN pfn = reinterpret_cast<PFN>(ee->getPointerToFunction(func));
    pfn();
    delete ee;
}

One oddity was that without the final include, ee is NULL. Bizarre.

To generate my tst.bc, I used http://llvm.org/demo/index.cgi and the llvm-as command-line tool.