如何在 CentOS 7 上通过 clang 构建 libcxx 和 libcxxabi
我想在 CentOS 7 上使用带有 clang/clang++ 的 C++11 或 C++14.如何构建这个构建环境?
I want to use C++11 or C++14 with clang/clang++ on CentOS 7. How do I build this building environment?
推荐答案
本文讲授如何在 CentOS 7 上搭建 C++11 构建环境:RHEL 的 EPEL repo 提供 Clang 包，但没有 C++ 库包.所以，这些部分手工制作有点麻烦.为 Clang 定制的 C++ 库是 libc++ (libcxx) [1].然后，libcxx 还需要一个 ABI 库，libc++abi (libcxxabi) [2].不幸的是，这两个库存在循环依赖问题.为了打破循环依赖问题，可以不链接 libc++abi 构建 libc++.然后，有了这个 libc++，我们就可以构建链接 libc++ 的 libc++abi.最后，通过libc++abi，我们可以构建一个新的libc++链接libc++abi.
This article teaches how to build C++11 building environment on CentOS 7: RHEL's EPEL repo provides Clang packages, but no C++ library packages. So, these parts are a bit troublesome to be built by hand. The customized C++ libraries for Clang is libc++ (libcxx) [1]. Then, libcxx also needs an ABI library, libc++abi (libcxxabi) [2]. Unfortunately, these two libraries have a circular dependency problem. For breaking the circular dependency problem, libc++ can be built without linking libc++abi. Then, with this libc++, we can build libc++abi linking libc++. Finally, with the libc++abi, we can build a new libc++ linking libc++abi.
clang、libc++、libc++abi环境搭建步骤如下:
The clang, libc++, and libc++abi environment building steps are given in the following：
添加 RHEL 的 EPEL 存储库.打开以下链接并找到如何使用这些额外的软件包?"部分https://fedoraproject.org/wiki/EPEL
找到你的 CentOS 版本的 epel 包.例如:
Add RHEL's EPEL repo. Open the following link and find the section "How can I use these extra packages?" https://fedoraproject.org/wiki/EPEL
Find the epel package for your CentOS version. E.g.,:
sudo rpm -i https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
安装 Subversion 以获得最新的 libcxx 和 libcxxabi.
Install Subversion for getting the latest libcxx and libcxxabi.
sudo yum install svn
安装 Clang 和 llvm-devel(使用 llvm-config).
Install Clang and llvm-devel (with llvm-config).
sudo yum install clang llvm-devel
安装 cmake.
Install cmake.
cd /usr/local
wget https://cmake.org/files/v3.5/cmake-3.5.2-Linux-i386.sh
sudo chmod 755 cmake-3.5.2-Linux-i386.sh
sudo ./cmake-3.5.2-Linux-i386.sh
# Check cmake is in /usr/local/bin.
在没有 libcxxabi 的情况下构建 libcxx 的第一轮.
1st round to build libcxx without libcxxabi.
# Get libcxx.
svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx
cd libcxx
# It is not recommended to build libcxx in the source root directory.
# So, we make a tmp directory.
mkdir tmp
cd tmp
# Specifying CMAKE_BUILD_TYPE to Release shall generate performance optimized code.
# The CMAKE_INSTALL_PREFIX changes the install path from the default /usr/local to /usr.
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ ..
sudo make install
cd ..
rm tmp -rf
cd ..
使用 libc++ 构建 libcxxabi.
Build libcxxabi with libc++.
# Get libcxxabi.
svn co http://llvm.org/svn/llvm-project/libcxxabi/trunk libcxxabi
cd libcxxabi
mkdir tmp
cd tmp
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DLIBCXXABI_LIBCXX_INCLUDES=../../libcxx/include ..
sudo make install
cd ../..
第二轮用 libcxxabi 构建 libcxx.
2nd round to build libcxx with libcxxabi.
cd libcxx
mkdir tmp
cd tmp
# This time, we want to compile libcxx with libcxxabi, so we have to specify LIBCXX_CXX_ABI=libcxxabi and the path to libcxxabi headers, LIBCXX_LIBCXXABI_INCLUDE_PATHS.
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DLIBCXX_CXX_ABI=libcxxabi -DLIBCXX_CXX_ABI_INCLUDE_PATHS=../../libcxxabi/include ..
sudo make install
编写一个 C++ 测试程序.
Write a C++ test program.
// t.cpp
#include <iostream>
using namespace std;
int main() {
cout << "Hello world!" << endl;
}
通过clang++测试C++编译.
Test C++ compilation by clang++.
# -std specifies the C++ standard. -stdlib specifies the C++ library you want to use with clang/clang++. -lc++abi is necessary, because the new LD (linker and loader) on CentOS 7 doesn't allow indirect library linking.
clang++ -std=c++11 -stdlib=libc++ -lc++abi t.cpp
./a.out
参考:
[1] http://libcxx.llvm.org/
[2] http://libcxxabi.llvm.org/
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