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// RUN: %libomp-compile-and-run
#include <stdio.h>
#include <stdlib.h>
#include <omp.h>
#include "omp_my_sleep.h"
int a = 0, b = 0;
int task_grabbed = 0, task_can_proceed = 0;
int task2_grabbed = 0, task2_can_proceed = 0;
static void wait_on_flag(int *flag) {
int flag_value;
int timelimit = 30;
int secs = 0;
do {
#pragma omp atomic read
flag_value = *flag;
my_sleep(1.0);
secs++;
if (secs == timelimit) {
fprintf(stderr, "error: timeout in wait_on_flag()\n");
exit(EXIT_FAILURE);
}
} while (flag_value == 0);
}
static void signal_flag(int *flag) {
#pragma omp atomic
(*flag)++;
}
int main(int argc, char** argv) {
// Ensure two threads are running
int num_threads = omp_get_max_threads();
if (num_threads < 2)
omp_set_num_threads(2);
#pragma omp parallel shared(a)
{
int a_value;
// Let us be extra safe here
if (omp_get_num_threads() > 1) {
#pragma omp single nowait
{
// Schedule independent child task that
// waits to be flagged after sebsequent taskwait depend()
#pragma omp task
{
signal_flag(&task_grabbed);
wait_on_flag(&task_can_proceed);
}
// Let another worker thread grab the task to execute
wait_on_flag(&task_grabbed);
// This should be ignored since the task above has
// no dependency information
#pragma omp task if(0) depend(inout: a)
{}
// Signal the independent task to proceed
signal_flag(&task_can_proceed);
// Schedule child task with dependencies that taskwait does
// not care about
#pragma omp task depend(inout: b)
{
signal_flag(&task2_grabbed);
wait_on_flag(&task2_can_proceed);
#pragma omp atomic
b++;
}
// Let another worker thread grab the task to execute
wait_on_flag(&task2_grabbed);
// This should be ignored since the task above has
// dependency information on b instead of a
#pragma omp task if(0) depend(inout: a)
{}
// Signal the task to proceed
signal_flag(&task2_can_proceed);
// Generate one child task for taskwait
#pragma omp task shared(a) depend(inout: a)
{
my_sleep(1.0);
#pragma omp atomic
a++;
}
#pragma omp task if(0) depend(inout: a)
{}
#pragma omp atomic read
a_value = a;
if (a_value != 1) {
fprintf(stderr, "error: dependent task was not executed before "
"taskwait finished\n");
exit(EXIT_FAILURE);
}
} // #pragma omp single
} // if (num_threads > 1)
} // #pragma omp parallel
return EXIT_SUCCESS;
}
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