# FindOpenMP

Finds Open Multi-Processing (OpenMP) support.

This module can be used to detect OpenMP support in a compiler. If the compiler supports OpenMP, the flags required to compile with OpenMP support are returned in variables for the different languages. The variables may be empty if the compiler does not need a special flag to support OpenMP.

Added in version 3.5: Clang support.

## Input Variables

The following variables may be set to influence this module's behavior:

`OpenMP_RUNTIME_MSVC`

  Added in version 3.30.

  Specify the OpenMP Runtime when compiling with MSVC. If set to a non-empty value, such as `experimental` or `llvm`, it will be passed as the value of the `-openmp:` flag.

## Result Variables

Added in version 3.10: The module exposes the components `C`, `CXX`, and `Fortran`. Each of these controls the various languages to search OpenMP support for.

Added in version 3.31: The `CUDA` language component is supported when using a CUDA compiler that supports OpenMP on the host.

Depending on the enabled components the following variables will be set:

`OpenMP_FOUND`

  Variable indicating that OpenMP flags for all requested languages have been found. If no components are specified, this is true if OpenMP settings for all enabled languages were detected.

`OpenMP_VERSION`

  Minimal version of the OpenMP standard detected among the requested languages, or all enabled languages if no components were specified.

This module will set the following variables per language in your project, where `<lang>` is one of C, CXX, CUDA, or Fortran:

`OpenMP_<lang>_FOUND`

  Variable indicating if OpenMP support for `<lang>` was detected.

`OpenMP_<lang>_FLAGS`

  OpenMP compiler flags for `<lang>`, separated by spaces.

`OpenMP_<lang>_INCLUDE_DIRS`

  Directories that must be added to the header search path for `<lang>` when using OpenMP.

For linking with OpenMP code written in `<lang>`, the following variables are provided:

`OpenMP_<lang>_LIB_NAMES`

  ;-list of libraries for OpenMP programs for `<lang>`.

`OpenMP_<libname>_LIBRARY`

  Location of the individual libraries needed for OpenMP support in `<lang>`.

`OpenMP_<lang>_LIBRARIES`

  A list of libraries needed to link with OpenMP code written in `<lang>`.

Additionally, the module provides `IMPORTED` targets:

`OpenMP::OpenMP_<lang>`

  Target for using OpenMP from `<lang>`.

Specifically for Fortran, the module sets the following variables:

`OpenMP_Fortran_HAVE_OMPLIB_HEADER`

  Boolean indicating if OpenMP is accessible through `omp_lib.h`.

`OpenMP_Fortran_HAVE_OMPLIB_MODULE`

  Boolean indicating if OpenMP is accessible through the `omp_lib` Fortran module.

The module will also try to provide the OpenMP version variables:

`OpenMP_<lang>_SPEC_DATE`

  Added in version 3.7.

  Date of the OpenMP specification implemented by the `<lang>` compiler.

`OpenMP_<lang>_VERSION_MAJOR`

  Major version of OpenMP implemented by the `<lang>` compiler.

`OpenMP_<lang>_VERSION_MINOR`

  Minor version of OpenMP implemented by the `<lang>` compiler.

`OpenMP_<lang>_VERSION`

  OpenMP version implemented by the `<lang>` compiler.

The specification date is formatted as given in the OpenMP standard: `yyyymm` where `yyyy` and `mm` represents the year and month of the OpenMP specification implemented by the `<lang>` compiler.

For some compilers, it may be necessary to add a header search path to find the relevant OpenMP headers. This location may be language-specific. Where this is needed, the module may attempt to find the location, but it can be provided directly by setting the `OpenMP_<lang>_INCLUDE_DIR` cache variable. Note that this variable is an _input_ control to the module. Project code should use the `OpenMP_<lang>_INCLUDE_DIRS` _output_ variable if it needs to know what include directories are needed.