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int simulate_thread_fini = 0;

void __attribute__((noinline))

simulate_thread_done ()

{

  simulate_thread_fini = 1;

}

/* A hostile thread is one which changes a memory location so quickly

   that another thread may never see the same value again.  This is

   simulated when simulate_thread_other_thread() is defined to modify

   a memory location every cycle.

   A process implementing a dependency on this value can run into

   difficulties with such a hostile thread.  For instance,

   implementing an add with a compare_and_swap loop goes something

   like:

     expected = *mem;

   loop:

     new = expected += value;

     if (!succeed (expected = compare_and_swap (mem, expected, new)))

       goto loop;

   If the content of 'mem' are changed every cycle by

   simulate_thread_other_thread () this will become an infinite loop

   since the value *mem will never be 'expected' by the time the

   compare_and_swap is executed.

   HOSTILE_THREAD_THRESHOLD defines the number of intructions which a

   program will execute before triggering the hostile thread

   pause. The pause will last for HOSTILE_THREAD_PAUSE instructions,

   and then the counter will reset and begin again.  During the pause

   period, simulate_thread_other_thread will not be called.

   This provides a chance for forward progress to be made and the

   infinite loop to be avoided.

   If the testcase defines HOSTILE_PAUSE_ERROR, then it will be

   considered a RUNTIME FAILURE if the hostile pause is triggered.

   This will allow to test for guaranteed forward progress routines.

   If the default values for HOSTILE_THREAD_THRESHOLD or

   HOSTILE_THREAD_PAUSE are insufficient, then the testcase may

   override these by defining the values before including this file.

   Most testcase are intended to run for very short periods of time,

   so these defaults are considered to be high enough to not trigger

   on a typical case, but not drag the test time out too much if a

   hostile condition is interferring.  */

/* Define the threshold instruction count to start pausing the hostile

   thread.  To avoid huge potential log files when things are not going well,

   set this number very low.  If a test specifically requires that the forward

   progress guarantee is made, this number should be raised by the testcase. */

#if !defined (HOSTILE_THREAD_THRESHOLD)

#define HOSTILE_THREAD_THRESHOLD        50

#endif

/* Define the length of pause in cycles for the hostile thread to pause to

   allow forward progress to be made.  If this number is too low, a

   compare_and_swap loop may not have time to finish, especially on a

   128 bit operation. */

#if !defined (HOSTILE_THREAD_PAUSE)

#define HOSTILE_THREAD_PAUSE    20

#endif

/* Define the number of instructions which are allowed to be executed before

   the testcase is deemed to fail.  This is primarily to avoid huge log files

   when a testcase goes into an infinte loop.  */

#if !defined (INSN_COUNT_THRESHOLD)

#define INSN_COUNT_THRESHOLD    10000

#endif

void simulate_thread_other_threads (void);

int simulate_thread_final_verify (void);

static int simulate_thread_hostile_pause = 0;

/* This function wraps simulate_thread_other_threads an monitors for

   an infinite loop.  If the threshold value HOSTILE_THREAD_THRESHOLD

   is reached, the other_thread process is paused for

   HOSTILE_THREAD_PAUSE cycles before resuming, and the counters start

   again.  */

int

simulate_thread_wrapper_other_threads()

{

  static int insn_count = 0;

  static int hostile_count = 0;

  static int hostile_pause = 0;

  if (++insn_count >= INSN_COUNT_THRESHOLD)

    {

      printf ("FAIL: Testcase exceeded maximum instruction count threshold\n");

      return 1;

    }

  if (++hostile_count >= HOSTILE_THREAD_THRESHOLD)

    {

      if (!simulate_thread_hostile_pause)

        simulate_thread_hostile_pause = 1;

      /* Count cycles before calling the hostile thread again.  */

      if (hostile_pause++ < HOSTILE_THREAD_PAUSE)

        return 0;

      /* Reset the pause counter, as well as the thread counter.  */

      hostile_pause = 0;

      hostile_count = 0;

    }

  simulate_thread_other_threads ();

  return 0;

}

/* If the test case defines HOSTILE_PAUSE_ERROR, then the test case

   will fail execution if it had a hostile pause.  */

int

simulate_thread_wrapper_final_verify ()

{

  int ret = simulate_thread_final_verify ();

#if defined (HOSTILE_PAUSE_ERROR)

  if (simulate_thread_hostile_pause)

    {

      printf ("FAIL: Forward progress made only by pausing hostile thread\n");

      ret = ret | 1;    /* 0 indicates proper comnpletion.  */

    }

#endif

  return ret;

}