[LLVMdev] Dynamic linking (dlopen/dlsym) against LLVM from a C program

[Jonathan Roelofs]

On 4/1/15 3:48 PM, Greg Stark wrote:
> [Resending as my previous message was sent to moderation. The list
> info page doesn't mention this is a subscriber only list]
>
> I'm trying to write a .so which will be loaded using dlopen and called
> using dlopen. The application is written in C and I want to use the
> LLVM C API jfrom it. Obviously it will end up calling C++ functions
> internally but as long as I expose a C API to the application I should
> be ok.
>
> I have a code that compiles fine but when I try to call it from the
> application dlopen complains about missing C++ symbols. It seems for
> some reason the LLVM shared libraries aren't being added to the ELF
> NEEDED lines even though other shared libraries are. I switched
> --as-needed to --no-as-needed but it hasn't helped.
>
> The link line I'm using is:
>
> clang -Wall -Wmissing-prototypes -Wpointer-arith
> -Wdeclaration-after-statement -Wendif-labels
> -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing
> -fwrapv -g -g -O0 -fpic -I/usr/lib/llvm-3.5/include  -DNDEBUG
> -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS
> -D__STDC_LIMIT_MACROS -g -O2 -fomit-frame-pointer -fPIC
> -Wno-ignored-attributes -shared -o pgjit.so pgjit.o
> -L/usr/local/pgsql/lib -Wl,--no-as-needed
> -Wl,-rpath,'/usr/local/pgsql/lib',-rpath,'/usr/lib/llvm-3.5/lib',--enable-new-dtags
> -I/usr/lib/llvm-3.5/include  -DNDEBUG -D_GNU_SOURCE
> -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
> -g -O2 -fomit-frame-pointer -std=c++11 -fvisibility-inlines-hidden
> -fno-exceptions -fPIC -Woverloaded-virtual -ffunction-sections
> -fdata-sections -Wcast-qual -L/usr/lib/llvm-3.5/lib  -lLLVMBitWriter
> -lLLVMX86Disassembler -lLLVMX86AsmParser -lLLVMX86CodeGen
> -lLLVMSelectionDAG -lLLVMAsmPrinter -lLLVMX86Desc -lLLVMObject
> -lLLVMMCParser -lLLVMBitReader -lLLVMX86Info -lLLVMX86AsmPrinter
> -lLLVMX86Utils -lLLVMInterpreter -lLLVMJIT -lLLVMCodeGen
> -lLLVMScalarOpts -lLLVMInstCombine -lLLVMTransformUtils -lLLVMipa
> -lLLVMAnalysis -lLLVMTarget -lLLVMExecutionEngine -lLLVMMC -lLLVMCore
> -lLLVMSupport -lz -lpthread -lffi -ledit -ltinfo -ldl -lm   -lm
>
> And the error I'm getting from dlopen is ERROR:  could not load
> library "/home/stark/src/pgjit/pgjit.so":
> /home/stark/src/pgjit/pgjit.so: undefined symbol:
> _ZTVN10__cxxabiv120__si_class_type_infoE

That particular symbol is in libcxxabi. I think you need `-lcxxabi -lc++`

>
> The NEEDED lines list all the non-llvm libraries but none of the llvm libraries:
>
> Dynamic Section:
>    NEEDED               libz.so.1
>    NEEDED               libpthread.so.0
>    NEEDED               libffi.so.6
>    NEEDED               libedit.so.2
>    NEEDED               libtinfo.so.5
>    NEEDED               libdl.so.2
>    NEEDED               libm.so.6
>    NEEDED               libgcc_s.so.1
>    NEEDED               libc.so.6
>    RUNPATH              /usr/local/pgsql/lib:/usr/lib/llvm-3.5/lib
>
> What am I doing wrong here?
>

-- 
Jon Roelofs
jonathan at codesourcery.com
CodeSourcery / Mentor Embedded