From 2c336a4d74461b9ff3a65bfcc630a3f9449894af Mon Sep 17 00:00:00 2001
From: Grzegorz Kowal <grzegorz@amuncode.org>
Date: Tue, 7 Dec 2021 10:37:56 -0300
Subject: [PATCH] CMAKE, MAKE: Add support for OpenMP.

Signed-off-by: Grzegorz Kowal <grzegorz@amuncode.org>
---
 CMakeLists.txt      | 10 ++++++++++
 build/hosts/default | 12 ++++++++++++
 build/make.default  |  2 ++
 sources/amun.F90    | 15 ++++++++++++++-
 4 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ddf8ada..0f1d8e4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -64,6 +64,16 @@ if(ENABLE_MPI)
 	endif()
 endif()
 
+option(ENABLE_OMP "Enable OpenMP support" ON)
+if(ENABLE_OMP)
+	find_package(OpenMP COMPONENTS Fortran)
+	if(OpenMP_Fortran_FOUND)
+		include_directories(${OpenMP_Fortran_INCLUDE_DIRS})
+		target_compile_options(amun.x PRIVATE "${OpenMP_Fortran_FLAGS}")
+		target_link_libraries(amun.x ${OpenMP_Fortran_LIBRARIES})
+	endif()
+endif()
+
 option(ENABLE_SIGNALS "Enables signal handler support" ON)
 if(ENABLE_SIGNALS)
 	target_compile_definitions(amun.x PRIVATE SIGNALS)
diff --git a/build/hosts/default b/build/hosts/default
index 173dde3..a296ebe 100644
--- a/build/hosts/default
+++ b/build/hosts/default
@@ -27,6 +27,9 @@ FFLAGS    = -Og -g -DDEBUG -fcheck=all
 else
 FFLAGS    = -O2 -march=native -pipe
 endif
+ifeq ($(OPENMP),Y)
+FFLAGS   += -fopenmp
+endif
 LDFLAGS   = $(FFLAGS)
 ifeq ($(STATIC),Y)
 LDFLAGS  += -static
@@ -56,6 +59,9 @@ FFLAGS    = -O0 -g -Mbounds -Mchkptr -Mcache_align -Mnovintr -Mchkstk -DDEBUG
 else
 FFLAGS    = -fast -O3
 endif
+ifeq ($(OPENMP),Y)
+FFLAGS   += -mp
+endif
 LDFLAGS   = $(FFLAGS)
 ifeq ($(STATIC),Y)
 LDFLAGS  += -Bstatic
@@ -85,6 +91,9 @@ FFLAGS    = -O -g -DDEBUG
 else
 FFLAGS    = -fast
 endif
+ifeq ($(OPENMP),Y)
+FFLAGS   += -mp
+endif
 LDFLAGS   = $(FFLAGS)
 ifeq ($(STATIC),Y)
 LDFLAGS  += -Bstatic
@@ -114,6 +123,9 @@ FFLAGS    = -O -g -DDEBUG
 else
 FFLAGS    = -O2 -xHost
 endif
+ifeq ($(OPENMP),Y)
+FFLAGS   += -openmp
+endif
 LDFLAGS   = $(FFLAGS)
 ifeq ($(STATIC),Y)
 LDFLAGS  += -static
diff --git a/build/make.default b/build/make.default
index 3bd5019..94fc1a5 100644
--- a/build/make.default
+++ b/build/make.default
@@ -15,8 +15,10 @@ SIGNALS      = N
 # parallelization flags:
 #
 #   MPI          - enable or disable MPI parallelization
+#   OPENMP       - enable or disable OpenMP parallelization
 #
 MPI          = N
+OPENMP       = N
 
 # output data format:
 #
diff --git a/sources/amun.F90 b/sources/amun.F90
index b51c864..725714e 100644
--- a/sources/amun.F90
+++ b/sources/amun.F90
@@ -65,6 +65,11 @@ program amun
   integer :: iin, iev, itm
   integer :: ed, eh, em, es
 
+! OpenMP
+!
+  integer :: nthreads = 1
+!$ integer :: omp_get_num_threads
+
 ! the format string
 !
   character(len=80) :: sfmt
@@ -131,8 +136,16 @@ program amun
   call print_welcome(verbose)
 #ifdef MPI
   call print_section(verbose, "Parallelization")
-  call print_parameter(verbose, "MPI processes", nprocs)
+  call print_parameter(verbose, "MPI processes" , nprocs)
+#else /* MPI */
+!$ call print_section(verbose, "Parallelization")
 #endif /* MPI */
+!$omp parallel
+!$omp master
+!$ nthreads = omp_get_num_threads()
+!$ call print_parameter(verbose, "OpenMP threads", nthreads)
+!$omp end master
+!$omp end parallel
 
 ! read parameters
 !