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