Fix restarted tags by separating the "same tag used by several instances of the same task" and the "same tag signaled by several tasks" thanks to setting submitted to 2 in the former case.

src/core/dependencies/tags.c

@@ -233,7 +233,12 @@ void _starpu_tag_declare(starpu_tag_t id, struct _starpu_job *job)
 
 	/* the tag is now associated to a job */
 	_starpu_spin_lock(&tag->lock);
-	if (tag->state != STARPU_DONE)
+	/* When the same tag may be signaled several times by different tasks,
+	 * and it's already done, we should not reset the "done" state.
+	 * When the tag is simply used by the same task several times, we have
+	 * to do so. */
+	if (job->task->regenerate || job->submitted == 2 ||
+			tag->state != STARPU_DONE)
 		tag->state = STARPU_ASSOCIATED;
 	_starpu_spin_unlock(&tag->lock);
 }

src/core/jobs.c

@@ -277,7 +277,10 @@ static unsigned _starpu_not_all_tag_deps_are_fulfilled(struct _starpu_job *j)
 	else
 	{
 		/* existing deps (if any) are fulfilled */
-		if (tag->state != STARPU_DONE)
+		/* If the same tag is being signaled by several tasks, do not
+		 * clear a DONE state. If it's the same job submitted several
+		 * times with the same tag, we have to do it */
+		if (j->submitted == 2 || tag->state != STARPU_DONE)
 			tag->state = STARPU_READY;
 		/* already prepare for next run */
 		tag_successors->ndeps_completed = 0;

src/core/jobs.h

@@ -91,7 +91,9 @@ LIST_TYPE(_starpu_job,
 	uint32_t footprint;
 
 	/* Indicates whether the task associated to that job has already been
-	 * submitted to StarPU or not (using starpu_task_submit). */
+	 * submitted to StarPU (1) or not (0) (using starpu_task_submit).
+	 * Becomes and stays 2 when the task is submitted several times.
+	 */
 	unsigned submitted;
 
 	/* Indicates whether the task associated to this job is terminated or

src/core/task.c

@@ -215,7 +215,10 @@ int _starpu_submit_job(struct _starpu_job *j)
 	/* Need to atomically set submitted to 1 and check dependencies, since
 	 * this is concucrent with _starpu_notify_cg */
 	j->terminated = 0;
-	j->submitted = 1;
+	if (!j->submitted)
+		j->submitted = 1;
+	else
+		j->submitted = 2;
 
 	int ret = _starpu_enforce_deps_and_schedule(j);