Error compiling Boost.Log

Question

I am trying to compile the boost log library and I keep getting this error from the dump_avx2.cpp file

error: always_inline function '_mm256_set1_epi32' requires target feature 'sse4.2', but would be inlined into function 'dump_data_avx2' that is compiled without support for 'sse4.2'
boost/boost/libs/log/src/dump_avx2.cpp:71:31: note: expanded from macro 'BOOST_LOG_AUX_MM_CONSTANTS'
    const __m256i mm_char_0 = _mm256_set1_epi32(0x30303030);\
                              ^

I get a lot of errors that are very similar to the one above, all of them have the same error message but different locations in the file where they occur, for reference I am on the commit hash 68701167a1020b0b4c47b76e31d3a3da9e2faf3f for the Boost.Log submodule as fetched from the github repo (https://github.com/boostorg/boost)

Does anyone know how I can go about resolving this issue? I am building with a C++14 compiler and this is what I get when I type g++ --version

Apple LLVM version 8.0.0 (clang-800.0.42.1)

Thanks!

Note I should clarify that in this context it is required that I compile this library separately.

Note There seem to be two related source files dump_ssse3.cpp and the mentioned dump_avx2.cpp file, do I have to compile only one of them? I cannot make out what to do from the Jamfile in the build folder :(

Answer 1

That looks like a bug in clang (LLVM). First, the intrinsic belongs to AVX2, not SSE4.2. Second, the whole dump_avx2.cpp file is compiled with -mavx2, so the required extensions are enabled. You can see the compiler switches in the error message from b2. And no, both dump_ssse3.cpp and dump_avx2.cpp should be compiled. The library does runtime detection of the available instructions in the CPU and selects the proper implementation.