FindOpenMP

Finds Open Multi-Processing (OpenMP) support in a compiler:

find_package(OpenMP [<version>] [COMPONENTS <components>...] [...])

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.

Components

This module supports components that can be specified using the standard syntax:

find_package(OpenMP [COMPONENTS <components>...])

Each of these components controls the various languages to search OpenMP support for. The following components are exposed:

C

Added in version 3.10.

CXX

Added in version 3.10.

Fortran

Added in version 3.10.

CUDA

Added in version 3.31.

The CUDA language component is supported when using a CUDA compiler that supports OpenMP on the host.

If no components are specified, module checks for all of them automatically.

Imported Targets

This module provides the following Imported Targets:

OpenMP::OpenMP_<lang>

Added in version 3.9.

Target encapsulating the OpenMP usage requirements for language <lang>.

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

This module defines the following variables:

OpenMP_FOUND

Boolean 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 the 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

semicolon-separated 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>.

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.

Examples

Finding OpenMP support and linking the imported target to a project target using the C language component:

find_package(OpenMP)
target_link_libraries(project_target PRIVATE OpenMP::OpenMP_C)