This is just a guess, but the DVB-T Viterbi decoder uses SSE2 intrinsics
for performance. In gnuradio/gr-dtv/lib/CMakeLists.txt, the flag
"-msse2" is added to CMAKE_CXX_FLAGS.
Ron
On 7/9/19 05:39, Corentin Basler wrote:
Hello everyone,
I'm actually doing my bachelor thesis about Just In Time compiler and
I want to integrate this technology in GNURadio. I've already created
OOT module with integrated JIT functionality. I'm now trying to add an
in-tree module. I'm trying to do that by copying the dvbt viterbi
decoder block. The JIT compiler that I use is : ClangJIT
<https://github.com/hfinkel/llvm-project-cxxjit/wiki> . For testing, I
use the example dvbt_rx_8k. I’m working from the maint-3.7 branch. I
added my new block and replace the originalviterbi decoderin the
example. Unfortunately, when running the application, I have the
following error :
Traceback (most recent call last):
File "/home/pacco/TB/gnuRadio_perf/dvbt_rx_demo_8k_jit.py", line 21,
in <module>
from gnuradio import dtv
File
"/opt/gnuradioClangJit/lib/python2.7/dist-packages/gnuradio/dtv/__init__.py",
line 34, in <module>
from dtv_swig import *
File
"/opt/gnuradioClangJit/lib/python2.7/dist-packages/gnuradio/dtv/dtv_swig.py",
line 17, in <module>
_dtv_swig = swig_import_helper()
File
"/opt/gnuradioClangJit/lib/python2.7/dist-packages/gnuradio/dtv/dtv_swig.py",
line 14, in swig_import_helper
return importlib.import_module(mname)
File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
__import__(name)
ImportError:
/opt/gnuradioClangJit/lib/libgnuradio-dtv-3.7.13.5.so.0.0.0: undefined
symbol:
_ZN2gr3dtv29dvbt_viterbi_decoder_jit_impl28dvbt_viterbi_get_output_sse2IXdtdefpT12d_ntracebackEEEhPDv2_xS4_Ph
I’ve already search in the mailing list for solution, but all the
solution that I’ve found are for OOT module.
When running c++filt, I get the following result :
unsigned char
gr::dtv::dvbt_viterbi_decoder_jit_impl::dvbt_viterbi_get_output_sse2<(*this).d_ntraceback>(long
long __vector(2)*, long long __vector(2)*, unsigned char*)
Which is the result I wanted to see.
I use the following cmake command when building from source :
cmake -DCMAKE_C_COMPILER=/opt/release/llvm/bin/clang
-DCMAKE_CXX_COMPILER=/opt/release/llvm/bin/clang++
-DPYTHON_EXECUTABLE=/usr/bin/python2
-DPYTHON_LIBRARY=/usr/lib/x86_64-linux-gnu/libpython2.7.so
-DCMAKE_INSTALL_PREFIX=/opt/gnuradioClangJit -DJIT_ENABLE=ON
-DENABLE_GR_UHD=OFF ../
CMAKE_C_COMPILER and CMAKE_CXX_COMPILER points to the llvm version
with clangJIT (see link above). JIT_ENABLE enable the flags for the
JIT compiler.
Every change that I’ve made are on the following git (and commit ):
https://github.com/Pacco1217/gnuradio/commit/14d656e5aecc998bb1cda9259de8a639dabf6d04
About the computer :
Kernel : 4.18.0-25-generic
OS : Ubuntu 18.10
Does anyone has already faced the same difficulties or having a
possible solution to this problem ?
Thanks in advance for your answers,
Basler Corentin
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