Compiling Python 3.4 with emscripten on Ubuntu (linkage errors)

Question

I am trying to build Python 3.4 from source, using emscripten.

I have downloaded and successfully installed emscripten. I have created a build folder outside the source tree. These are the steps I have carried out so far:

Run configure: $ emconfigure ../Python-3.4.3/configure --without-threads --without-pymalloc --enable-shared --disable-ipv6 --build=i686-linux-gnu
I noticed that a check for LONG_BIT in ../Python-3.4.3/Include/pyport.h conflicts with the #define SIZEOF_LONG defined in one of emscriptens headers, so I have commented out the check in ../Python-3.4.3/Include/pyport.h
After running configure successfully, I then run emmmake make in my build folder
I check that the built python file is indeed LLVM bytecode by running file python. Having satisfied myself that all is well, I attempt to link the generated libpython3-4.so with the bytecode as follows:

$ llvm-link libpython3.4.so python -o python.bc

I get the following error message:

ERROR: Linking globals named '_Py_open_cloexec_works': symbol multiply defined!

A quick search through the source code shows the symbol is NOT multiply defined:

$ grep -rnw ../Python-3.4.3 -e "_Py_open_cloexec_works" --include=\*.{c,h}
../Python-3.4.3/Python/fileutils.c:33:int _Py_open_cloexec_works = -1;
../Python-3.4.3/Python/fileutils.c:784:    atomic_flag_works = &_Py_open_cloexec_works;
../Python-3.4.3/Modules/posixmodule.c:7702:extern int _Py_open_cloexec_works;
../Python-3.4.3/Modules/posixmodule.c:7725:    int *atomic_flag_works = &_Py_open_cloexec_works;
../Python-3.4.3/Modules/_io/fileio.c:210:extern int _Py_open_cloexec_works;
../Python-3.4.3/Modules/_io/fileio.c:232:    int *atomic_flag_works = &_Py_open_cloexec_works;

So I run nm on libpython3.4.so, to check the exported symbols, and I got the following error message:

nm: libpython3.4.so: File format not recognised

I have run out of ideas now. Can anyone help me solve the linkage issues?

[[ Additional Info ]]

clang version 3.6.0
LLVM version 3.6.0svn

Cosmin Iovan · Accepted Answer · 2015-05-05 19:24:42Z

0

Instead of nm, you can use the powerful objdump. Try objdump -t you_file or objdump -T you_file.

Example: objdump -t lib.o

answered May 5, 2015 at 19:24

Cosmin Iovan

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2 Comments

Homunculus Reticulli Over a year ago

I just checked the file type for the generated .so file. It turns out its LLVM bitcode, so nm and objdump both do not recognise the file format.

Cosmin Iovan Over a year ago

Try to compile python with g++5 , for me worked perfect.

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