libgomp/testsuite/libgomp.c/appendix-a/a.2.1.c

   1 /* { dg-do run } */
   2
   3 #include <stdio.h>
   4 #include <omp.h>
   5 extern void abort (void);
   6 int
   7 main ()
   8 {
   9   int bad, x;
  10   x = 2;
  11   bad = 0;
  12 #pragma omp parallel num_threads(2) shared(x, bad)
  13   {
  14     if (omp_get_thread_num () == 0)
  15       {
  16         volatile int i;
  17         for (i = 0; i < 100000000; i++)
  18           x = 5;
  19       }
  20     else
  21       {
  22         /* Print 1: the following read of x has a race */
  23         if (x != 2 && x != 5)
  24           bad = 1;
  25       }
  26 #pragma omp barrier
  27     if (omp_get_thread_num () == 0)
  28       {
  29         /* x must be 5 now.  */
  30         if (x != 5)
  31           bad = 1;
  32       }
  33     else
  34       {
  35         /* x must be 5 now.  */
  36         if (x != 5)
  37           bad = 1;
  38       }
  39   }
  40
  41   if (bad)
  42     abort ();
  43
  44   return 0;
  45 }