Add omp API for omp set get nested which is need by mkl

src/intel_hpxMP.cpp

@@ -1002,4 +1002,11 @@ void omp_unset_nest_lock(omp_lock_t **lock) {
     (*lock)->unlock();
 }
 
+void omp_set_nested(int val){
+    #if defined DEBUG && defined HPXMP_HAVE_TRACE
+        std::cout<<"hpxMP always sets nested to true"<<std::endl;
+    #endif
+    start_backend();
+};
+int omp_get_nested(){return 1;};
 

src/intel_hpxMP.h

@@ -265,6 +265,9 @@ extern "C" void omp_unset_nest_lock(omp_lock_t **lock);
 extern "C" int omp_test_lock(omp_lock_t **lock);
 extern "C" int omp_test_nest_lock(omp_lock_t **lock);
 
+extern "C" void omp_set_nested(int val);
+extern "C" int omp_get_nested();
+
 #if HPXMP_HAVE_OMP_50_ENABLED
 extern "C" void *__kmpc_task_reduction_init(int gtid, int num, void *data);
 extern "C" void *__kmpc_task_reduction_get_th_data(int gtid, void *tskgrp, void *data);

tests/openmp/unit/CMakeLists.txt

@@ -22,6 +22,7 @@ set(tests
         for_static
         master
         max_threads
+        omp_set_get_nested
         par_for
         par_nested
         par_single

tests/openmp/unit/omp_set_get_nested.cpp

@@ -0,0 +1,34 @@
+// Copyright (c) 2018 Tianyi Zhang
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <iostream>
+#include <stdio.h>
+#include <omp.h>
+
+using namespace std;
+
+int main()
+{
+    int number;
+    int i;
+    omp_set_num_threads(4);
+    omp_set_nested(1); // 1 - enables nested parallelism; 0 - disables nested parallelism.
+
+#pragma omp parallel // parallel region begins
+    {
+        printf("outer parallel region Thread ID == %d\n", omp_get_thread_num());
+        /*
+            Code for work to be done by outer parallel region threads over here.
+        */
+#pragma omp parallel num_threads(2) // nested parallel region
+        {
+            /*
+                Code for work to be done by inner parallel region threads over here.
+            */
+            printf("inner parallel region thread id %d\n", omp_get_thread_num());
+        }
+    }
+    return 0;
+}