Add an OpenMP dependency.

This works similarly to the thread dependency which stores the various
inconsistent flags in each compiler.

14 files changed, 151 insertions, 4 deletions

diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 916f680..694700e 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -540,6 +540,8 @@ class Backend:
             # pkg-config puts the thread flags itself via `Cflags:`
             if dep.need_threads():
                 commands += compiler.thread_flags(self.environment)
+            elif dep.need_openmp():
+                commands += compiler.openmp_flags()
         # Fortran requires extra include directives.
         if compiler.language == 'fortran':
             for lt in target.link_targets:
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index 7d86473..7bdd2d1 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -2551,6 +2551,8 @@ rule FORTRAN_DEP_HACK
         for d in target.external_deps:
             if d.need_threads():
                 commands += linker.thread_link_flags(self.environment)
+            elif d.need_openmp():
+                commands += linker.openmp_flags()
         # Only non-static built targets need link args and link dependencies
         if not isinstance(target, build.StaticLibrary):
             commands += target.link_args
diff --git a/mesonbuild/backend/vs2010backend.py b/mesonbuild/backend/vs2010backend.py
index e9a3519..4959e6e 100644
--- a/mesonbuild/backend/vs2010backend.py
+++ b/mesonbuild/backend/vs2010backend.py
@@ -824,7 +824,10 @@ class Vs2010Backend(backends.Backend):
         for d in reversed(target.get_external_deps()):
             # Cflags required by external deps might have UNIX-specific flags,
             # so filter them out if needed
-            d_compile_args = compiler.unix_args_to_native(d.get_compile_args())
+            if isinstance(d, dependencies.OpenMPDependency):
+                d_compile_args = compiler.openmp_flags()
+            else:
+                d_compile_args = compiler.unix_args_to_native(d.get_compile_args())
             for arg in d_compile_args:
                 if arg.startswith(('-D', '/D')):
                     define = arg[2:]
@@ -915,11 +918,17 @@ class Vs2010Backend(backends.Backend):
             for dep in target.get_external_deps():
                 # Extend without reordering or de-dup to preserve `-L -l` sets
                 # https://github.com/mesonbuild/meson/issues/1718
-                extra_link_args.extend_direct(dep.get_link_args())
+                if isinstance(dep, dependencies.OpenMPDependency):
+                    extra_link_args.extend_direct(compiler.openmp_flags())
+                else:
+                    extra_link_args.extend_direct(dep.get_link_args())
             for d in target.get_dependencies():
                 if isinstance(d, build.StaticLibrary):
                     for dep in d.get_external_deps():
-                        extra_link_args.extend_direct(dep.get_link_args())
+                        if isinstance(dep, dependencies.OpenMPDependency):
+                            extra_link_args.extend_direct(compiler.openmp_flags())
+                        else:
+                            extra_link_args.extend_direct(dep.get_link_args())
         # Add link args for c_* or cpp_* build options. Currently this only
         # adds c_winlibs and cpp_winlibs when building for Windows. This needs
         # to be after all internal and external libraries so that unresolved
diff --git a/mesonbuild/compilers/c.py b/mesonbuild/compilers/c.py
index 4263536..279e435 100644
--- a/mesonbuild/compilers/c.py
+++ b/mesonbuild/compilers/c.py
@@ -296,6 +296,8 @@ class CCompiler(Compiler):
             args += d.get_compile_args()
             if d.need_threads():
                 args += self.thread_flags(env)
+            elif d.need_openmp():
+                args += self.openmp_flags()
             if mode == 'link':
                 # Add link flags needed to find dependencies
                 args += d.get_link_args()
@@ -1086,6 +1088,9 @@ class VisualStudioCCompiler(CCompiler):
     def build_rpath_args(self, build_dir, from_dir, rpath_paths, build_rpath, install_rpath):
         return []
 
+    def openmp_flags(self):
+        return ['/openmp']
+
     # FIXME, no idea what these should be.
     def thread_flags(self, env):
         return []
diff --git a/mesonbuild/compilers/compilers.py b/mesonbuild/compilers/compilers.py
index 99e9164..a383095 100644
--- a/mesonbuild/compilers/compilers.py
+++ b/mesonbuild/compilers/compilers.py
@@ -937,6 +937,9 @@ class Compiler:
     def thread_flags(self, env):
         return []
 
+    def openmp_flags(self):
+        raise EnvironmentException('Language %s does not support OpenMP flags.' % self.get_display_language())
+
 
 GCC_STANDARD = 0
 GCC_OSX = 1
@@ -1152,6 +1155,9 @@ class GnuCompiler:
     def get_default_include_dirs(self):
         return gnulike_default_include_dirs(self.exelist, self.language)
 
+    def openmp_flags(self):
+        return ['-fopenmp']
+
 
 class ElbrusCompiler(GnuCompiler):
     # Elbrus compiler is nearly like GCC, but does not support
@@ -1270,6 +1276,14 @@ class ClangCompiler:
     def get_default_include_dirs(self):
         return gnulike_default_include_dirs(self.exelist, self.language)
 
+    def openmp_flags(self):
+        if version_compare(self.version, '>=3.8.0'):
+            return ['-fopenmp']
+        elif version_compare(self.version, '>=3.7.0'):
+            return ['-fopenmp=libomp']
+        else:
+            return None
+
 
 # Tested on linux for ICC 14.0.3, 15.0.6, 16.0.4, 17.0.1
 class IntelCompiler:
@@ -1332,6 +1346,12 @@ class IntelCompiler:
     def get_default_include_dirs(self):
         return gnulike_default_include_dirs(self.exelist, self.language)
 
+    def openmp_flags(self):
+        if version_compare(self.version, '>=15.0.0'):
+            return ['-qopenmp']
+        else:
+            return ['-openmp']
+
 
 class ArmCompiler:
     # Functionality that is common to all ARM family compilers.
diff --git a/mesonbuild/compilers/fortran.py b/mesonbuild/compilers/fortran.py
index 5bb3ec9..9d3240f 100644
--- a/mesonbuild/compilers/fortran.py
+++ b/mesonbuild/compilers/fortran.py
@@ -180,6 +180,9 @@ class GnuFortranCompiler(FortranCompiler):
         """
         return ['-Wl,--out-implib=' + implibname]
 
+    def openmp_flags(self):
+        return ['-fopenmp']
+
 
 class ElbrusFortranCompiler(GnuFortranCompiler, ElbrusCompiler):
     def __init__(self, exelist, version, gcc_type, is_cross, exe_wrapper=None, defines=None, **kwargs):
@@ -231,6 +234,9 @@ class SunFortranCompiler(FortranCompiler):
     def get_module_outdir_args(self, path):
         return ['-moddir=' + path]
 
+    def openmp_flags(self):
+        return ['-xopenmp']
+
 
 class IntelFortranCompiler(IntelCompiler, FortranCompiler):
     std_warn_args = ['-warn', 'all']
@@ -263,6 +269,10 @@ class PathScaleFortranCompiler(FortranCompiler):
     def get_std_warn_args(self, level):
         return PathScaleFortranCompiler.std_warn_args
 
+    def openmp_flags(self):
+        return ['-mp']
+
+
 class PGIFortranCompiler(FortranCompiler):
     std_warn_args = ['-Minform=inform']
 
@@ -282,6 +292,9 @@ class PGIFortranCompiler(FortranCompiler):
     def get_no_warn_args(self):
         return ['-silent']
 
+    def openmp_flags(self):
+        return ['-fopenmp']
+
 
 class Open64FortranCompiler(FortranCompiler):
     std_warn_args = ['-fullwarn']
@@ -296,6 +309,9 @@ class Open64FortranCompiler(FortranCompiler):
     def get_warn_args(self, level):
         return Open64FortranCompiler.std_warn_args
 
+    def openmp_flags(self):
+        return ['-mp']
+
 
 class NAGFortranCompiler(FortranCompiler):
     std_warn_args = []
@@ -309,3 +325,6 @@ class NAGFortranCompiler(FortranCompiler):
 
     def get_warn_args(self, level):
         return NAGFortranCompiler.std_warn_args
+
+    def openmp_flags(self):
+        return ['-openmp']
diff --git a/mesonbuild/dependencies/__init__.py b/mesonbuild/dependencies/__init__.py
index 4796980..1c67311 100644
--- a/mesonbuild/dependencies/__init__.py
+++ b/mesonbuild/dependencies/__init__.py
@@ -18,7 +18,7 @@ from .base import (  # noqa: F401
     ExternalDependency, ExternalLibrary, ExtraFrameworkDependency, InternalDependency,
     PkgConfigDependency, find_external_dependency, get_dep_identifier, packages, _packages_accept_language)
 from .dev import GMockDependency, GTestDependency, LLVMDependency, ValgrindDependency
-from .misc import (MPIDependency, Python3Dependency, ThreadDependency, PcapDependency, CupsDependency, LibWmfDependency)
+from .misc import (MPIDependency, OpenMPDependency, Python3Dependency, ThreadDependency, PcapDependency, CupsDependency, LibWmfDependency)
 from .platform import AppleFrameworks
 from .ui import GLDependency, GnuStepDependency, Qt4Dependency, Qt5Dependency, SDL2Dependency, WxDependency, VulkanDependency
 
@@ -33,6 +33,7 @@ packages.update({
     # From misc:
     'boost': BoostDependency,
     'mpi': MPIDependency,
+    'openmp': OpenMPDependency,
     'python3': Python3Dependency,
     'threads': ThreadDependency,
     'pcap': PcapDependency,
@@ -53,4 +54,5 @@ packages.update({
 })
 _packages_accept_language.update({
     'mpi',
+    'openmp',
 })
diff --git a/mesonbuild/dependencies/base.py b/mesonbuild/dependencies/base.py
index 4127081..2a19544 100644
--- a/mesonbuild/dependencies/base.py
+++ b/mesonbuild/dependencies/base.py
@@ -134,6 +134,9 @@ class Dependency:
     def get_exe_args(self, compiler):
         return []
 
+    def need_openmp(self):
+        return False
+
     def need_threads(self):
         return False
 
diff --git a/mesonbuild/dependencies/misc.py b/mesonbuild/dependencies/misc.py
index 2a218be..30cb541 100644
--- a/mesonbuild/dependencies/misc.py
+++ b/mesonbuild/dependencies/misc.py
@@ -237,6 +237,19 @@ class MPIDependency(ExternalDependency):
                     [os.path.join(libdir, 'msmpi.lib')])
 
 
+class OpenMPDependency(ExternalDependency):
+    def __init__(self, environment, kwargs):
+        super().__init__('openmp', environment, None, {})
+        self.is_found = True
+        mlog.log('Dependency', mlog.bold(self.name), 'found:', mlog.green('YES'))
+
+    def need_openmp(self):
+        return True
+
+    def get_version(self):
+        return 'unknown'
+
+
 class ThreadDependency(ExternalDependency):
     def __init__(self, environment, kwargs):
         super().__init__('threads', environment, None, {})
diff --git a/mesonbuild/linkers.py b/mesonbuild/linkers.py
index 8e491d9..cb07c5e 100644
--- a/mesonbuild/linkers.py
+++ b/mesonbuild/linkers.py
@@ -56,6 +56,9 @@ class VisualStudioLinker(StaticLinker):
     def thread_link_flags(self, env):
         return []
 
+    def openmp_flags(self):
+        return []
+
     def get_option_link_args(self, options):
         return []
 
@@ -114,6 +117,9 @@ class ArLinker(StaticLinker):
     def thread_link_flags(self, env):
         return []
 
+    def openmp_flags(self):
+        return []
+
     def get_option_link_args(self, options):
         return []
 
diff --git a/test cases/common/190 openmp/main.c b/test cases/common/190 openmp/main.c
new file mode 100644
index 0000000..cc81f48
--- /dev/null
+++ b/test cases/common/190 openmp/main.c
@@ -0,0 +1,16 @@
+#include <stdio.h>
+#include <omp.h>
+
+int main(void) {
+#ifdef _OPENMP
+    if (omp_get_max_threads() == 2) {
+        return 0;
+    } else {
+        printf("Max threads is %d not 2.\n", omp_get_max_threads());
+        return 1;
+    }
+#else
+    printf("_OPENMP is not defined; is OpenMP compilation working?\n");
+    return 1;
+#endif
+}
diff --git a/test cases/common/190 openmp/main.cpp b/test cases/common/190 openmp/main.cpp
new file mode 100644
index 0000000..b12be3f
--- /dev/null
+++ b/test cases/common/190 openmp/main.cpp
@@ -0,0 +1,16 @@
+#include <iostream>
+#include <omp.h>
+
+int main(void) {
+#ifdef _OPENMP
+    if (omp_get_max_threads() == 2) {
+        return 0;
+    } else {
+        std::cout << "Max threads is " << omp_get_max_threads() << " not 2." << std::endl;
+        return 1;
+    }
+#else
+    printf("_OPENMP is not defined; is OpenMP compilation working?\n");
+    return 1;
+#endif
+}
diff --git a/test cases/common/190 openmp/main.f90 b/test cases/common/190 openmp/main.f90
new file mode 100644
index 0000000..c062d86
--- /dev/null
+++ b/test cases/common/190 openmp/main.f90
@@ -0,0 +1,8 @@
+program main
+    if (omp_get_max_threads() .eq. 2) then
+        stop 0
+    else
+        print *, 'Max threads is', omp_get_max_threads(), 'not 2.'
+        stop 1
+    endif
+end program main
diff --git a/test cases/common/190 openmp/meson.build b/test cases/common/190 openmp/meson.build
new file mode 100644
index 0000000..0455955
--- /dev/null
+++ b/test cases/common/190 openmp/meson.build
@@ -0,0 +1,26 @@
+project('openmp', 'c', 'cpp')
+
+openmp = dependency('openmp')
+
+exec = executable('exec',
+  'main.c',
+  dependencies : [openmp])
+
+execpp = executable('execpp',
+  'main.cpp',
+  dependencies : [openmp])
+
+env = environment()
+env.set('OMP_NUM_THREADS', '2')
+
+test('OpenMP C', exec, env : env)
+test('OpenMP C++', execpp, env : env)
+
+
+if add_languages('fortran', required : false)
+  exef = executable('exef',
+    'main.f90',
+    dependencies : [openmp])
+
+  test('OpenMP Fortran', execpp, env : env)
+endif