Update

openmp/6-fibo-deps-v0.cpp

+#include <iostream>
+#include <omp.h>
+
+int fibonacci(int n)
+{
+  if (n<2)
+   return n;
+
+  int sum;
+  int r1;
+  int r2;
+  #pragma omp task depend(out:r1) shared(r1) firstprivate(n)
+    r1 = fibonacci(n-1);
+  #pragma omp task depend(out:r2) shared(r2) firstprivate(n)
+    r2 = fibonacci(n-2);
+  #pragma omp task depend(out:sum) depend(in:r1,r2) shared(r1,r2,sum)
+    sum = r1 + r2;
+  #pragma omp taskwait
+  return sum;
+}
+
+int main(int argc, char** argv)
+{
+  int r, n;
+  n = atoi(argv[1]);
+  double t0 = omp_get_wtime();
+#pragma omp parallel shared(r) firstprivate(n)
+  {
+#pragma omp master
+    {
+#pragma omp task depend(out:r) firstprivate(n) shared(r)
+      r = fibonacci( n );
+#pragma omp task depend(in:r) firstprivate(n) shared(r)
+      {
+        double t1 = omp_get_wtime();
+        std::cout <<"Fibonacci(" << n << ") =" << r << std::endl;
+        std::cout << "Time: " << t1-t0 << std::endl;
+      }
+    }
+  }
+
+  return 0;
+}

openmp/6-fibo-deps-v1.cpp

+#include <iostream>
+#include <omp.h>
+
+int fibonacci(int n)
+{
+  if (n<2)
+   return n;
+
+  int sum;
+  int r1;
+  int r2;
+  #pragma omp task if (n>20) depend(out:r1) shared(r1) firstprivate(n)
+    r1 = fibonacci(n-1);
+  #pragma omp task if (n>20) depend(out:r2) shared(r2) firstprivate(n)
+    r2 = fibonacci(n-2);
+  #pragma omp task if (n>20) depend(out:sum) depend(in:r1,r2) shared(r1,r2,sum)
+    sum = r1 + r2;
+  #pragma omp taskwait
+  return sum;
+}
+
+int main(int argc, char** argv)
+{
+  int r, n;
+  n = atoi(argv[1]);
+  double t0 = omp_get_wtime();
+#pragma omp parallel shared(r) firstprivate(n)
+  {
+#pragma omp master
+    {
+#pragma omp task depend(out:r) firstprivate(n) shared(r)
+      r = fibonacci( n );
+#pragma omp task depend(in:r) firstprivate(n) shared(r)
+      {
+        double t1 = omp_get_wtime();
+        std::cout <<"Fibonacci(" << n << ") =" << r << std::endl;
+        std::cout << "Time: " << t1-t0 << std::endl;
+      }
+    }
+  }
+
+  return 0;
+}

openmp/6-fibo-v0.cpp

+#include <iostream>
+#include <omp.h>
+
+int fibonacci(const int n)
+{
+  if (n<2)
+    return n;
+  else {
+    int r1,r2;
+#pragma omp task shared(r2) firstprivate(n)
+    r2 = fibonacci( n-2 );
+#pragma omp task shared(r1) firstprivate(n)
+    r1 = fibonacci( n-1 );
+#pragma omp taskwait
+    return r1 + r2;
+  }
+}
+
+int main(int argc, char** argv)
+{
+  int r, n;
+  n = atoi(argv[1]);
+  double t0 = omp_get_wtime();
+#pragma omp parallel shared(r) firstprivate(n)
+  {
+#pragma omp master
+    {
+#pragma omp task shared(r) firstprivate(n)
+      r = fibonacci( n );
+#pragma omp taskwait
+    }
+  }
+  double t1 = omp_get_wtime();
+  std::cout << "Fibonacci(" << n << ") =" << r << std::endl;
+  std::cout << "Time: " << t1-t0 << std::endl;
+  
+  return 0;
+}
+

openmp/6-fibo-v1.cpp

+#include <iostream>
+#include <omp.h>
+
+int fibonacci(const int n)
+{
+  if (n<2)
+    return n;
+  else {
+    int r1,r2;
+#pragma omp task shared(r2) firstprivate(n)
+    r2 = fibonacci( n-2 );
+
+    r1 = fibonacci( n-1 );
+#pragma omp taskwait
+    return r1 + r2;
+  }
+}
+
+int main(int argc, char** argv)
+{
+  int r, n;
+  n = atoi(argv[1]);
+  double t0 = omp_get_wtime();
+#pragma omp parallel shared(r) firstprivate(n)
+  {
+#pragma omp master
+    {
+#pragma omp task shared(r) firstprivate(n)
+      r = fibonacci( n );
+    }
+  }
+  double t1 = omp_get_wtime();
+  std::cout <<"Fibonacci(" << n << ") =" << r << std::endl;
+  std::cout << "Time: " << t1-t0 << std::endl;
+
+  return 0;
+}
+

openmp/6-fibo-v2.cpp

+#include <iostream>
+#include <omp.h>
+
+int fibonacci(const int n)
+{
+  if (n<2)
+    return n;
+  else {
+    int r1,r2;
+#pragma omp task if (n>10) shared(r2) firstprivate(n)
+    r2 = fibonacci( n-2 );
+
+    r1 = fibonacci( n-1 );
+#pragma omp taskwait
+    return r1 + r2;
+  }
+}
+
+int main(int argc, char** argv)
+{
+  int r, n;
+  n = atoi(argv[1]);
+  double t0 = omp_get_wtime();
+#pragma omp parallel shared(r) firstprivate(n)
+  {
+#pragma omp master
+    {
+#pragma omp task shared(r) firstprivate(n)
+      r = fibonacci( n );
+    }
+  }
+  double t1 = omp_get_wtime();
+  std::cout <<"Fibonacci(" << n << ") =" << r << std::endl;
+  std::cout << "Time: " << t1-t0 << std::endl;
+
+  return 0;
+}
+