[LLVMdev] 2.6/trunk Execution Engine question

[Kenneth Uildriks]

And I should not forget to mention that passing "true" as the last
parameter to ExecutionEngine::create makes the test program work and
finish with the output line "gv = 24601"

On Tue, Oct 6, 2009 at 6:45 PM, Kenneth Uildriks <kennethuil at gmail.com> wrote:
>>
>> It just occurred to me... in the case where it's failing, the
>> ExecutionEngine was trying to JIT a global, and it had never JITted
>> any functions!  I'll work up a small test case, but I think it's
>> relevant since the thing is trying to allocate the globals with the
>> functions.
>>
>
> That was it!  The following small test program crashes in getPointerToGlobal:
>
> #include "llvm/Module.h"
> #include "llvm/Function.h"
> #include "llvm/InlineAsm.h"
> #include "llvm/Support/IRBuilder.h"
> #include "llvm/ModuleProvider.h"
> #include "llvm/ExecutionEngine/ExecutionEngine.h"
> #include "llvm/Support/raw_os_ostream.h"
> #include "llvm/Bitcode/ReaderWriter.h"
> #include "llvm/Support/raw_ostream.h"
> #include "llvm/Target/TargetSelect.h"
> #include "llvm/ExecutionEngine/JIT.h"
>
> #include <assert.h>
>
> using namespace llvm;
>
> static raw_stdout_ostream raw_cout;
>
> int main(int argc, char** argv)
> {
>        // Test JITting a variable without JITting any functions.'
>        Module* mod = new Module("test", getGlobalContext());
>        GlobalVariable* gv = cast<GlobalVariable>(mod->getOrInsertGlobal("TestGV",
>                        Type::getInt32Ty(getGlobalContext())));
>        gv->setInitializer(ConstantInt::get(
>                Type::getInt32Ty(getGlobalContext()), 24601));
>
>        ModuleProvider* modp = new ExistingModuleProvider(mod);
>        InitializeNativeTarget();
>        std::string errstring;
>
>        ExecutionEngine* eeng = ExecutionEngine::create(modp, false, &errstring,
>                        CodeGenOpt::Default, true);
>        if ( eeng == NULL )
>        {
>                raw_cout << errstring << "\n";
>                exit(-1);
>        }
>        raw_cout << "Fixing to get pointer to global\n";
>        void* gvp = eeng->getPointerToGlobal(gv);
>        raw_cout << "Got pointer to global\n";
>        raw_cout << "gv = " << *((int*)gvp) << "\n";
>        exit(0);
> }
>