我试图在Mavericks上让我的程序运行openmp，但是当我尝试使用标志-fopenmp编译时，我会得到以下错误：
ld: library not found for -lgomp
clang: error: linker command failed with exit code 1 (use -v to see invocation)
gcc myProgram.cpp -fopenmp -o myProgram
此外，当我运行gcc时，会出现Clang的警告，这让我感到非常奇怪。而查看/usr/bin/gcc时，似乎没有链接到Clang。
有什么建议可以修复我的Clang错误并使openmp编译成功吗？
brew install gcc49]，但似乎gcc仍然被链接到Clang。$g++ --version Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn) Target: x86_64-apple-darwin13.0.0 Thread model: posix/usr/local目录下安装软件。请确保/usr/local/bin已经被添加到了$PATH环境变量中，并且它在/usr/bin之前。此外，从Homebrew安装的GCC二进制文件可能会带有版本后缀，例如gcc-4.9而不是简单的gcc。 - Hristo Iliev我最近解决了这个问题，并根据官方说明编写了获取所有工作内容的脚本。
该脚本将下载所有内容到~/code以便于维护，并将正确的环境变量附加到您的~/.profile文件中。对于高级用户，请选择一个您想要手动移动lib、bin和include的好位置。脚本依赖于了解来自Intel的最新OpenMP运行时，可以在脚本顶部更改。
该脚本应该可以直接在普通Mavericks上使用，除了一个小问题。在OpenML运行时创建脚本时，它不可靠地接受指定的clang并继续默认的GCC。因此，如果您没有安装GCC（这在开箱即用的Mavericks上不是正常情况），它将无法构建。为了解决此问题，您必须注释掉两行代码（如脚本中所示），基于OpenMP的libomp_20131209_oss.tgz版本。更新的OpenML版本可能会破坏此脚本，因此在较新的版本上使用需自担风险。
只需将此脚本保存到文件中，运行'chmod +x filename.sh'，然后从终端运行'./filename.sh'即可。构建LLVM和Clang需要一段时间，请耐心等待。
编辑：这个脚本在Yosemite上很可能会失败，我在将操作系统更新到10.10的dev版本后使用内置的clang2出现了问题。
INTEL_OPENMP_LATEST_BUILD_LINK=https://www.openmprtl.org/sites/default/files/libomp_20131209_oss.tgz
DEST_FOLDER = ~/code
CLANG_INCLUDE=${DEST_FOLDER}/llvm/include
CLANG_BIN=${DEST_FOLDER}/llvm/build/Debug+Asserts/bin
CLANG_LIB=${DEST_FOLDER}/llvm/build/Debug+Asserts/lib
OPENMP_INCLUDE=${DEST_FOLDER}/libomp_oss/exports/common/include
OPENMP_LIB=${DEST_FOLDER}/libomp_oss/exports/mac_32e/lib.thin
mkdir ${DEST_FOLDER}
cd ${DEST_FOLDER}
git clone https://github.com/clang-omp/llvm
git clone https://github.com/clang-omp/compiler-rt llvm/projects/compiler-rt
git clone -b clang-omp https://github.com/clang-omp/clang llvm/tools/clang
cd llvm
mkdir build
cd build
../configure
make
cd Debug+Asserts/bin
mv clang clang2
rm -rf clang++
ln -s clang2 clang2++
echo "LLVM+Clang+OpenMP Include Path : " ${CLANG_INCLUDE}
echo "LLVM+Clang+OpenMP Bin Path : " ${CLANG_BIN}
echo "LLVM+Clang+OpenMP Lib Path : " ${CLANG_LIB}
cd ${DEST_FOLDER}
curl ${INTEL_OPENMP_LATEST_BUILD_LINK} -o libomp_oss_temp.tgz
gunzip -c libomp_oss_temp.tgz | tar xopf -
rm -rf libomp_oss_temp.tgz
cd libomp_oss
echo "You need to do one or two things:"
echo "1.) [Required] Comment out line 433 from libomp_oss/src/makefile.mk"
echo "2.) [Optional] If you do not have GCC installed (not normal on vanilla Mavericks), you must comment out lines 450-451 in libomp_oss/tools/check-tools.pl. Have you done this or want to compile anyway?"
select yn in "Yes" "No"; do
case $yn in
Yes ) make compiler=clang; break;;
No ) exit;;
esac
done
echo "OpenMP Runtime Include Path : " ${OPENMP_INCLUDE}
echo "OpenMP Runtime Lib Path : " ${OPENMP_LIB}
(echo 'export PATH='${CLANG_BIN}':$PATH';
echo 'export C_INCLUDE_PATH='${CLANG_INCLUDE}':'${OPENMP_INCLUDE}':$C_INCLUDE_PATH';
echo 'export CPLUS_INCLUDE_PATH='${CLANG_INCLUDE}':'${OPENMP_INCLUDE}':$CPLUS_INCLUDE_PATH';
echo 'export LIBRARY_PATH='${CLANG_LIB}':'${OPENMP_LIB}':$LIBRARY_PATH';
echo 'export DYLD_LIBRARY_PATH='${CLANG_LIB}':'${OPENMP_LIB}':$DYLD_LIBRARY_PATH}') >> ~/.profile
source ~/.profile
echo "LLVM+Clang+OpenMP is now accessible through [ clang2 ] via terminal and does not conflict with Apple's clang"
我刚刚解决了这个问题。以下是答案以及如何在Xcode中使用它。
Grab the latest version of openMP runtime library from https://www.openmprtl.org/download
unzip and compile it by
mkdir build && cd build && cmake .. && make && sudo make install
install it by
sudo cp ./libiomp5.dylib /usr/lib/
sudo cp ./omp.h /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/
Grab openmp/clang from Git following the instructions on http://clang-omp.github.io/
compile openmp/clang
cd llvm && mkdir build && cd build && ../configure --enable-optimized && make -j
sudo make install
normally it would install clang/clang++ into /usr/local/bin, we need replace the Apple clang with our version
cd /usr/bin
sudo mv clang clang-apple
sudo mv clang++ clang++-apple
sudo ln -s /usr/local/bin/clang ./clang
sudo ln -s /usr/local/bin/clang++ ./clang++
cd /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
sudo mv clang clang-apple
sudo mv clang++ clang++-apple
sudo ln -s /usr/local/bin/clang ./clang
sudo ln -s /usr/local/bin/clang++ ./clang++
cd /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1
sudo mv -f * ../../
Create a project in Xcode, using the Hello World code on clang-openmp website for test. After created, add "-fopenmp" to Custom Compiler Flags -> Other C Flags in project settings; add /usr/lib/libiomp5.dylib to the build phases of project (project settings -> Build Phases -> Drag /usr/lib/libiomp5.dylib into Link Binary with Libraries)
It should work. Yosemite + Xcode 6 is tested.
注意：自定义的clang不如苹果公司的稳定。如果编译后出现奇怪的指令错误，请切换回原先的版本。
gcc吗？你能检查一下gcc --version吗？ - keltar$gcc --version
配置为：--prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM版本5.0（clang-500.2.79）（基于LLVM 3.3svn）
目标：x86_64-apple-darwin13.0.0
线程模型：posix - Davy Li