32

我正在学习 LLVM Tutorial，但我在编译时遇到了问题。我写了一个最小的例子来重现这个问题：

#include "llvm/Module.h"
#include "llvm/LLVMContext.h"

int main(int argc, char **argv) {
    llvm::Module *module = new llvm::Module("test", llvm::getGlobalContext());
    return 0;
}

当我尝试编译时，我得到一堆“未定义的引用”错误：

clang++ `llvm-config --cxxflags`   -c -o test.o test.cpp
clang++  test.o  `llvm-config --ldflags --libs core` -o test
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Signals.o): In function `PrintStackTrace(void*)':
(.text+0x6c): undefined reference to `dladdr'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Signals.o): In function `PrintStackTrace(void*)':
(.text+0x1f6): undefined reference to `dladdr'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Mutex.o): In function `llvm::sys::MutexImpl::MutexImpl(bool)':
(.text+0x53): undefined reference to `pthread_mutexattr_init'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Mutex.o): In function `llvm::sys::MutexImpl::MutexImpl(bool)':
(.text+0x64): undefined reference to `pthread_mutexattr_settype'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Mutex.o): In function `llvm::sys::MutexImpl::MutexImpl(bool)':
(.text+0x74): undefined reference to `pthread_mutexattr_setpshared'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Mutex.o): In function `llvm::sys::MutexImpl::MutexImpl(bool)':
(.text+0x88): undefined reference to `pthread_mutexattr_destroy'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Mutex.o): In function `llvm::sys::MutexImpl::tryacquire()':
(.text+0x179): undefined reference to `pthread_mutex_trylock'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::RWMutexImpl()':
(.text+0x3e): undefined reference to `pthread_rwlock_init'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::~RWMutexImpl()':
(.text+0x80): undefined reference to `pthread_rwlock_destroy'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::reader_acquire()':
(.text+0xb9): undefined reference to `pthread_rwlock_rdlock'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::reader_release()':
(.text+0xe9): undefined reference to `pthread_rwlock_unlock'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::writer_acquire()':
(.text+0x119): undefined reference to `pthread_rwlock_wrlock'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::writer_release()':
(.text+0x149): undefined reference to `pthread_rwlock_unlock'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Threading.o): In function `llvm::llvm_execute_on_thread(void (*)(void*), void*, unsigned int)':
(.text+0x1cc): undefined reference to `pthread_create'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Threading.o): In function `llvm::llvm_execute_on_thread(void (*)(void*), void*, unsigned int)':
(.text+0x208): undefined reference to `pthread_attr_setstacksize'
/usr/lib/llvm-2.9/lib/libLLVMSupport.a(Threading.o): In function `llvm::llvm_execute_on_thread(void (*)(void*), void*, unsigned int)':
(.text+0x228): undefined reference to `pthread_join'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [test] Error 1

如果我查看 dladdr 的手册页，它说我需要链接到-ldl. 但我已经这样做了llvm-config：

$ llvm-config --ldflags --libs core
-L/usr/lib/llvm-2.9/lib  -lpthread -lffi -ldl -lm 
-lLLVMCore -lLLVMSupport -L/usr/lib/llvm-2.9/lib

此外，-ldl以正确的顺序出现（即，在.o需要符号的文件之后）。

我对调试此问题的下一步感到茫然。谁能指出我正确的方向？我在 Ubuntu 12.04 上运行 LVVM 2.9-7。

4

2 回答 2

35

需要符号的库包含在 中-lLLVMSupport，因此-ldl必须在 之后-lLLVMSupport。我改变了这个：

`llvm-config --ldflags --libs core`

对此：

`llvm-config --libs core` `llvm-config --ldflags`

并且链接器是成功的。

于 2012-10-20T23:15:17.790 回答
12

在浏览 llvm-3.4 的 LLVM 教程时，我遇到了同样的问题，不幸的是，Matthew 的回答没有帮助。为了将来参考，我发布了一个新的答案，其中包含我遇到的问题以及我如何解决它。

我已经在 中安装了 LLVM ~/dev/llvm/install，所以我使用的是教程中给出的命令，但替换llvm-config为我的 llvm 安装路径：

clang++ -g -O3 toy.cpp `../llvm/install/bin/llvm-config --cppflags --ldflags --libs core` -o toy

我有很多错误，第一个是：

filipe@filipe-Kubuntu:~/dev/kaleidoscope$ clang++ -g -O3 toy.cpp `../llvm/install/bin/llvm-config --cppflags --ldflags --libs core` -o toy
In file included from toy.cpp:1:
In file included from /home/filipe/dev/llvm/install/include/llvm/IR/Verifier.h:24:
/home/filipe/dev/llvm/install/include/llvm/ADT/StringRef.h:342:14: error: no template named 'enable_if' in namespace 'std'; did you mean
      '__gnu_cxx::__enable_if'?
    typename std::enable_if<std::numeric_limits<T>::is_signed, bool>::type
             ^~~~~~~~~~~~~~
             __gnu_cxx::__enable_if
/usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/ext/type_traits.h:43:12: note: '__gnu_cxx::__enable_if' declared here
    struct __enable_if 
           ^

这是因为此时 LLVM 需要 C++11 编译器；添加-std=c++11到clang++选项解决了它。但后来我得到：

filipe@filipe-Kubuntu:~/dev/kaleidoscope$ clang++ -std=c++11 -g -O3 toy.cpp `../llvm/install/bin/llvm-config --cppflags --ldflags --libs core` -o toy
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(Process.o): In function `terminalHasColors(int)':
/home/filipe/dev/llvm/llvm/lib/Support/Unix/Process.inc:273: undefined reference to `setupterm'
/home/filipe/dev/llvm/llvm/lib/Support/Unix/Process.inc:291: undefined reference to `tigetnum'
/home/filipe/dev/llvm/llvm/lib/Support/Unix/Process.inc:295: undefined reference to `set_curterm'
/home/filipe/dev/llvm/llvm/lib/Support/Unix/Process.inc:296: undefined reference to `del_curterm'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(Signals.o): In function `llvm::sys::PrintStackTrace(_IO_FILE*)':
/home/filipe/dev/llvm/llvm/lib/Support/Unix/Signals.inc:278: undefined reference to `dladdr'
/home/filipe/dev/llvm/llvm/lib/Support/Unix/Signals.inc:290: undefined reference to `dladdr'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(Mutex.o): In function `MutexImpl':
/home/filipe/dev/llvm/llvm/lib/Support/Mutex.cpp:53: undefined reference to `pthread_mutexattr_init'
/home/filipe/dev/llvm/llvm/lib/Support/Mutex.cpp:59: undefined reference to `pthread_mutexattr_settype'
/home/filipe/dev/llvm/llvm/lib/Support/Mutex.cpp:67: undefined reference to `pthread_mutexattr_destroy'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(Mutex.o): In function `llvm::sys::MutexImpl::tryacquire()':
/home/filipe/dev/llvm/llvm/lib/Support/Mutex.cpp:109: undefined reference to `pthread_mutex_trylock'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(RWMutex.o): In function `RWMutexImpl':
/home/filipe/dev/llvm/llvm/lib/Support/RWMutex.cpp:59: undefined reference to `pthread_rwlock_init'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(RWMutex.o): In function `~RWMutexImpl':
/home/filipe/dev/llvm/llvm/lib/Support/RWMutex.cpp:72: undefined reference to `pthread_rwlock_destroy'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::reader_acquire()':
/home/filipe/dev/llvm/llvm/lib/Support/RWMutex.cpp:82: undefined reference to `pthread_rwlock_rdlock'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::reader_release()':
/home/filipe/dev/llvm/llvm/lib/Support/RWMutex.cpp:92: undefined reference to `pthread_rwlock_unlock'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::writer_acquire()':
/home/filipe/dev/llvm/llvm/lib/Support/RWMutex.cpp:102: undefined reference to `pthread_rwlock_wrlock'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(RWMutex.o): In function `llvm::sys::RWMutexImpl::writer_release()':
/home/filipe/dev/llvm/llvm/lib/Support/RWMutex.cpp:112: undefined reference to `pthread_rwlock_unlock'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(ThreadLocal.o): In function `ThreadLocalImpl':
/home/filipe/dev/llvm/llvm/lib/Support/ThreadLocal.cpp:56: undefined reference to `pthread_key_create'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(ThreadLocal.o): In function `~ThreadLocalImpl':
/home/filipe/dev/llvm/llvm/lib/Support/ThreadLocal.cpp:63: undefined reference to `pthread_key_delete'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(ThreadLocal.o): In function `llvm::sys::ThreadLocalImpl::setInstance(void const*)':
/home/filipe/dev/llvm/llvm/lib/Support/ThreadLocal.cpp:70: undefined reference to `pthread_setspecific'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(ThreadLocal.o): In function `llvm::sys::ThreadLocalImpl::getInstance()':
/home/filipe/dev/llvm/llvm/lib/Support/ThreadLocal.cpp:77: undefined reference to `pthread_getspecific'
/home/filipe/dev/llvm/install/lib/libLLVMSupport.a(Threading.o): In function `llvm::llvm_execute_on_thread(void (*)(void*), void*, unsigned int)':
/home/filipe/dev/llvm/llvm/lib/Support/Threading.cpp:91: undefined reference to `pthread_attr_setstacksize'
/home/filipe/dev/llvm/llvm/lib/Support/Threading.cpp:96: undefined reference to `pthread_create'
/home/filipe/dev/llvm/llvm/lib/Support/Threading.cpp:100: undefined reference to `pthread_join'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

与原始问题的作者发生的情况相反，我注意到llvm-config甚至没有链接到任何系统库。然后我想我需要使用--system-libs才能将所需的系统库包含到链接过程中：

clang++ -std=c++11 -g -O3 toy.cpp `../llvm/install/bin/llvm-config --cppflags --libs core --ldflags --system-libs` -o toy

始终放在--system-libs最后很重要，以便链接器引入所有缺少的依赖项。

使用 LLVM 3.4 和 Kubuntu 14.04 测试

于 2014-04-26T18:00:58.447 回答