MCJIT/interpreter and iostream

As of LLVM 3.2, is it possible to use iostream with the MCJIT or interpreter execution engines? I'm getting some errors...

Each of these commands correctly prints "hello":

  echo -e '#include <stdio.h>\nint main(){ printf("hello"); }' | clang -cc1 -emit-llvm-bc -x c++ | lli -use-mcjit

  echo -e '#include <iostream>\nint main(){ std::cout << "hello" << std::endl; }' | clang -cc1 -emit-llvm-bc -x c++ | lli

Each of these commands results in "LLVM ERROR: Could not resolve external global address: __dso_handle":

  echo -e '#include <iostream>\nint main(){ std::cout << "hello" << std::endl; }' | clang -cc1 -emit-llvm-bc -x c++ | lli -force-interpreter=true

  echo -e '#include <iostream>\nint main(){ std::cout << "hello" << std::endl; }' | clang -cc1 -emit-llvm-bc -x c++ | lli -use-mcjit

This command correctly prints "hello":

  echo -e '#include <iostream>\nextern "C" {void *__dso_handle = NULL;} int main(){ std::cout << "hello" << std::endl; }' | clang -cc1 -emit-llvm-bc -x c++ | lli

This command results in "LLVM ERROR: Tried to execute an unknown external function: _ZNSt8ios_base4InitC1Ev"

  echo -e '#include <iostream>\nextern "C" {void *__dso_handle = NULL;} int main(){ std::cout << "hello" << std::endl; }' | clang -cc1 -emit-llvm-bc -x c++ | lli -force-interpreter=true

This command results in "Assertion failed: (FPtr && "Pointer to fn's code was null after getPointerToFunction"), function runFunction, file MCJIT.cpp, line 180."

  echo -e '#include <iostream>\nextern "C" {void *__dso_handle = NULL;} int main(){ std::cout << "hello" << std::endl; }' | clang -cc1 -emit-llvm-bc -x c++ | lli -use-mcjit

Try using '-fno-use-cxa-atexit' with clang. That should get rid of the use of '__dso_handle'.

Arguably, MCJIT and the interpreter should be able to handle this case, but they currently don't. There's a very old bug against the interpreter regarding this (http://llvm.org/bugs/show_bug.cgi?id=7847). If anyone needs this in MCJIT, we should probably open a bugzilla report for that too.

-Andy