Troubleshooting

You can enable verbose logging using two environment variables:

• DEBUG: if set, enable additional (possibly costly) run-time checks, and some more verbose output
• TRACE: if set, the DEBUG level will be activated, in addition with a trace of every call to the underlying library

In order to avoid run-time cost for checking the log level, these flags are implemented by means of global constants. As a result, you need to run Julia with precompilation disabled if you want to modify these flags:

$ TRACE=1 julia --compilecache=no examples/sum.jl 1 2
TRACE: LLVM.jl is running in trace mode, this will generate a lot of additional output
...

Enabling colors with --color=yes is also recommended as it color-codes the output.

Building llvm-extra fails due to C++11 ABI issues

The build step might fail at building the llvm-extra wrapper with errors like the following:

IR/Pass.o:(.data.rel.ro._ZTVN4llvm15JuliaModulePassE[_ZTVN4llvm15JuliaModulePassE]+0x40): undefined reference to `llvm::ModulePass::createPrinterPass(llvm::raw_ostream&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
IR/Pass.o:(.data.rel.ro._ZTVN4llvm17JuliaFunctionPassE[_ZTVN4llvm17JuliaFunctionPassE]+0x40): undefined reference to `llvm::FunctionPass::createPrinterPass(llvm::raw_ostream&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
IR/Pass.o:(.data.rel.ro._ZTVN4llvm19JuliaBasicBlockPassE[_ZTVN4llvm19JuliaBasicBlockPassE]+0x40): undefined reference to `llvm::BasicBlockPass::createPrinterPass(llvm::raw_ostream&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
collect2: error: ld returned 1 exit status

IR/Pass.o:(.data.rel.ro._ZTVN4llvm15JuliaModulePassE[_ZTVN4llvm15JuliaModulePassE]+0x40): undefined reference to `llvm::ModulePass::createPrinterPass(llvm::raw_ostream&, std::string const&) const'
IR/Pass.o:(.data.rel.ro._ZTVN4llvm17JuliaFunctionPassE[_ZTVN4llvm17JuliaFunctionPassE]+0x40): undefined reference to `llvm::FunctionPass::createPrinterPass(llvm::raw_ostream&, std::string const&) const'
IR/Pass.o:(.data.rel.ro._ZTVN4llvm19JuliaBasicBlockPassE[_ZTVN4llvm19JuliaBasicBlockPassE]+0x40): undefined reference to `llvm::BasicBlockPass::createPrinterPass(llvm::raw_ostream&, std::string const&) const'
collect2: error: ld returned 1 exit status

These indicate a mismatch between the C++ ABI of the LLVM library (more specifically, caused by the C++11 ABI change), and what your compiler selects by default. The Makefile in this package tries to detect any C++11 ABI symbols in the selected LLVM library and configures GLIBC accordingly, but this detection might fail when objdump is not available on your system, or might not help if the target compiler doesn't support said ABI.

Most if these issues can be fixed by using the same compiler LLVM was build with to compile llvm-extra. You can override the selected compiler by defining the CC and CXX environment variables, eg. CC=clang CXX=clang++ julia -e 'Pkg.build("LLVM")'.