Trouble linking against LLVM with project including Flex and Bison

问题

I've been working through a tutorial on writing compilers with Flex, Bison, and LLVM (http://gnuu.org/2009/09/18/writing-your-own-toy-compiler/), and attempting to compile the final binary fails with many of the following "undefined reference" errors:

g++ -o parser `llvm-config --libs core jit native --cxxflags --ldflags` *.cpp
/tmp/ccl0CSyi.o: In function `NBinaryOperator::codeGen(CodeGenContext&)':
codegen.cpp:(.text+0x2ce): undefined reference to     `llvm::BinaryOperator::Create(llvm::Instruction::BinaryOps, llvm::Value*, llvm::Value*,     llvm::Twine const&, llvm::BasicBlock*)'
/tmp/ccl0CSyi.o: In function `NDouble::codeGen(CodeGenContext&)':
codegen.cpp:(.text+0x3db): undefined reference to `llvm::getGlobalContext()'
codegen.cpp:(.text+0x3e3): undefined reference to     `llvm::Type::getDoubleTy(llvm::LLVMContext&)'
/tmp/ccl0CSyi.o: In function `NInteger::codeGen(CodeGenContext&)':
...
collect2: ld returned 1 exit status
make: *** [parser] Error 1

As far as I know, I have all the necessary includes and the llvm-config script is working correctly --- does anybody have any idea how to resolve these errors?

回答1:

You need to put the libraries AFTER the source files on the command line

回答2:

You may use:

clang++ -g -O3 toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core` -o toy

Hope this helps.

来源：https://stackoverflow.com/questions/5207734/trouble-linking-against-llvm-with-project-including-flex-and-bison