[LLVMdev] MCJIT/interpreter and iostream

[Jaymie Strecker]

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


---
Jaymie Strecker
jstr...@kosada.com




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[Kaylor, Andrew]

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