--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libgomp/testsuite/libgomp.c/appendix-a/a.18.1.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,67 @@
+/* { dg-do run } */
+
+#include <omp.h>
+#include <stdio.h>
+
+extern void abort (void);
+
+#define NUMBER_OF_THREADS 4
+
+int synch[NUMBER_OF_THREADS];
+int work[NUMBER_OF_THREADS];
+int result[NUMBER_OF_THREADS];
+int
+fn1 (int i)
+{
+  return i * 2;
+}
+
+int
+fn2 (int a, int b)
+{
+  return a + b;
+}
+
+int
+main ()
+{
+  int i, iam, neighbor;
+  omp_set_num_threads (NUMBER_OF_THREADS);
+#pragma omp parallel private(iam,neighbor) shared(work,synch)
+  {
+    iam = omp_get_thread_num ();
+    synch[iam] = 0;
+#pragma omp barrier
+    /*Do computation into my portion of work array */
+    work[iam] = fn1 (iam);
+    /* Announce that I am done with my work. The first flush
+     * ensures that my work is made visible before synch.
+     * The second flush ensures that synch is made visible.
+     */
+#pragma omp flush(work,synch)
+    synch[iam] = 1;
+#pragma omp flush(synch)
+    /* Wait for neighbor. The first flush ensures that synch is read
+     * from memory, rather than from the temporary view of memory.
+     * The second flush ensures that work is read from memory, and
+     * is done so after the while loop exits.
+     */
+    neighbor = (iam > 0 ? iam : omp_get_num_threads ()) - 1;
+    while (synch[neighbor] == 0)
+      {
+#pragma omp flush(synch)
+      }
+#pragma omp flush(work,synch)
+    /* Read neighbor's values of work array */
+    result[iam] = fn2 (work[neighbor], work[iam]);
+  }
+  /* output result here */
+  for (i = 0; i < NUMBER_OF_THREADS; i++)
+    {
+      neighbor = (i > 0 ? i : NUMBER_OF_THREADS) - 1;
+      if (result[i] != i * 2 + neighbor * 2)
+	abort ();
+    }
+
+  return 0;
+}