Clang openmp mac os

• Add a new user-defined setting CC with the value /usr/local/bin/clang-omp
• Add -fopenmp to Other C Flags
• Add /usr/local/include to Header Search Paths
• Set Enable Modules (C and Objective-C) to No .

• Add /usr/local/lib/libiomp5.dylib to Link Binary With Libraries

A simple example

Confirm that the compiler is working correctly by saving the above code to a file.

Compilation should proceed with no errors or warnings.

Execute the output ./hello . You should see more than one “Hello” line with different thread numbers. Note that the lines may be mixed together. If you see only one, try setting the environment variable OMP_NUM_THREADS to some number (say 4) and try again.

If you would like to see performance impact, you can try to compile and execute a more complex example Matrices Multiplication.

Contribute

We welcome contributions of all kinds: patches, code reviews, testing and bug reports.

However, as any other open source project, we have to maintain some level of control to prevent complete chaos and keep a single architectural direction. You can send your patches here for review and commit; also, we are very open with granting commit access rights to recognized members of Clang/LLVM community.

We plan eventually to contribute this OpenMP implementation to the Clang trunk, where it will be governed by existing Clang/LLVM community development policies.

Status

Full support for OpenMP 3.1 and most of OpenMP 4.0 features (except for offloading) are implemented. This implementation relies on the Intel OpenMP API, and should be used along with Intel® OpenMP* Runtime Library that supports that API (available from www.openmprtl.org).

The following openly available OpenMP test suites pass:

• OpenMP Validation Suite by OpenUH Research Compiler — passed 119 tests of 123.

Supported platforms

OS: Linux or Mac OS X
Architecture: x86, x86-64, PowerPC, Arm

Important Note

Please note that this is a preliminary version. While everything is carefully tested and works fine, there are known internal design quality issues. We plan to refactor some parts of the code before submitting them to Clang trunk. And yes, any help with this would be appreciated!

Among known design issues are:

• Combined constructs ( #pragma omp parallel for and #pragma omp parallel sections ). Currently these constructs are represented as a pair of #pragma omp parallel and #pragma omp for/sections constructs. This solution leads to ugly representation in AST because of the troubles with the variables capturing.
• Calculation of iteration indices for #pragma omp for is not quite optimal. AST representation of this construct also is not very good and should be re-designed.
• Analysis of atomic constructs and loops should be reworked for better diagnostics and readability.

Also, please note that this development is based on latest released clang (3.5), not what is currently under development in clang trunk.

External Projects

License

LLVM, Clang, and Compiler-rt are distributed under LLVM’s the University of Illinois/NCSA Open Source License. In addition to the «UIUC» BSD-Style license license, the runtime library component of LLVM (Compiler_rt) is also licensed under the MIT License. For details, including information about third-party components, see LICENSE.txt in the code repositories.

Contact

If you would like to report a bug, or make a feature request, you can submit an issue in Github here.

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Использование OpenMP с C ++ 11 в Mac OS

Я пытаюсь использовать некоторые функции многопоточности OpenMP в моем коде C ++ 11, например:

Когда я пытаюсь скомпилировать с помощью:

Я получаю ошибку ниже:

В качестве альтернативы я попытался с помощью компиляции:

Но это дает точно такую ​​же ошибку.

Был бы очень признателен, если бы вы могли посоветовать, как я могу скомпилировать код C ++ 11, который имеет функции OpenMP в Mac OS 10.12. Другие вопросы о постах здесь и в других местах объясняют компиляцию кода C для OpenMP, однако я не смог найти ничего для C ++ 11.

При попытке установить libiomp я получаю сообщение об ошибке:

Если я использую g ++ — 6, основываясь на посте Марка Сетчелла, приведенного ниже, он работает нормально, спасибо, однако я получаю следующие предупреждения, буду признателен за любые предложения о том, как их избежать:

Решение

Обновленный ответ

Поскольку мой оригинальный ответ ниже, ситуация улучшилась, и вы можете легко использовать OpenMP с clang++ компилятор — ураааай!

Для этого сначала используйте доморощенного установить brew install libomp :

Тогда при использовании clang++ используйте эти флаги:

Оригинальный ответ

Если вы хотите скомпилировать код C ++ 11 OpenMP на OSX, самый простой способ — это использовать gcc который вы можете установить через homebrew ,

Сначала проверьте доступные варианты:

Пример вывода

Итак, я подозреваю, что вы хотите:

После того, как вы установили его, вы должны убедиться, что вы используете homebrew версия, а не та, которую поставляет Apple. Вы должны знать, что homebrew устанавливает все в /usr/local/bin и что компилятор C ++ g++-6 , Итак, вам нужно либо скомпилировать:

или настройте свой PATH в своем профиле входа в систему:

тогда вы можете просто сделать:

Обратите внимание, что если вы выберете второй вариант выше (то есть export PATH=. вариант), вам также нужно будет также ввести export введите команду в текущем сеансе один раз, чтобы активировать ее, или выйдите из системы и снова войдите в систему, поскольку команды вашего профиля выполняются только при входе в систему.

AFAIK, нет необходимости явно устанавливать libiomp — не уверен, почему ты это сделал.

Другие решения

Clang, который поставляется с XCode, не поддерживает OpenMP, однако тот из llvm.org поддерживает. Есть инструкция по установке .

По умолчанию в OSX GCC является просто символической ссылкой на Clang (согласно комментарию к Компиляция программ OpenMP с компилятором gcc на OS X Yosemite ). Вы можете установить настоящий GCC из Homebrew, который определенно поддерживает OpenMP.

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OpenMP on macOS with Xcode tools

OpenMP support in Xcode

Apple has explicitly disabled OpenMP support in compilers that they ship in Xcode: even though clang had OpenMP support for quite a long time now (great thanks to the folks at Intel providing their library as open source!). In fact, the clang compiler in Xcode can generate all the necessary code for OpenMP. It can be tricked into performing its designed function by using -Xclang -fopenmp flags.

The unfortunate part about this is that Apple is not shipping the necesssary libomp.dylib run-time library needed for OpenMP support. To make things worse, the version of the library you need depends on the clang version used, which Apple obfuscates so that it’s non-trivial to reverse-engineer it. Fortunately, some clever folks were able to find the traces in Apple’s released source so we can build the binaries that correspond to the clang version used. It is sometimes possible to use a more recent version of the runtime than the version of Apple clang.

OpenMP run-time downloads

How to enable OpenMP in packages

• Download the libomp run-time corresponding to the Xcode version you use from the links above
• add -Xclang -fopenmp to CPPFLAGS, add -lomp to LIBS

How you do the latter depends on the package, but if the package does not set these environment variables itself, you can try If that doesn’t work, please consult the package’s documentation, and liaise with its maintainer. It is also possible to add those flags globally by adding the following to

/.R/Makevars: but be very careful when doing this, always check your

/.R/Makevars whenever you upgrade R, macOS or Xcode.

Side notes

License and sources

Acknowledgements

Trademark notices

• The OpenMP name and the OpenMP logo are registered trademarks of the OpenMP Architecture Review Board.
• Intel is a trademark of Intel Corporation in the U.S. and/or other countries.
• Apple, Xcode and macOS are trademarks of Apple Inc., registered in the U.S. and other countries.

Last modified on 2020/05/01 by Simon Urbanek

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Using OpenMP with C++11 on Mac OS

I am trying to use some OpenMP multithreading features in my C++11 code like:

When I try to compile using:

I get the below error:

I alternatively tried compiling using:

But this gives the exact same error.

Would appreciate very much if you could advise how can I compile C++11 code that has OpenMP features on Mac OS 10.12. The other questions on posts here and elsewhere explain compiling C code for OpenMP, however, I couldn’t find anything for C++11.

I get an error when I try to install libiomp, I get errors:

If I run using g++-6, based on Mark Setchell’s post below, it works fine, thanks, I however get the below warnings, would appreciate any suggestions on how to avoid these:

2 Answers 2

Updated Answer

Since my original answer below, the situation has improved and you can easily use OpenMP with the clang++ compiler — hurraaaay!

To do that, first use homebrew to install brew install libomp :

Then when using clang++ , use these flags:

Original Answer

If you want to compile C++11 OpenMP code on OSX, the easiest way is to use gcc which you can install via homebrew .

First, check the available options:

Sample Output

So, I suspect you want:

Once you have got it installed, you need to make sure you are using the homebrew version rather than the one Apple supplies. You need to know that homebrew installs everything in /usr/local/bin and that the C++ compiler is g++-6 . So, you either need to compile with:

or, set up your PATH in your login profile:

then you can just do:

Note that if you choose the second option above (i.e. the export PATH=. option), you will either need to also type the export command in your current session once to activate it, or log out and log back in since your profile commands are only executed on login.

AFAIK, there is no need to explicitly install libiomp — not sure why you did that.

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