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Fixed problem introduced by part of https://reviews.llvm.org/D21196. 

Check Task Scheduling Constraint (TSC) on stealing of untied task.
This is needed because the untied task can produce tied children
those can break TSC if untied is not a descendant of current task.
This can cause live lock on complex tyasking tests
(e.g. kastors/strassen-task-dep).

Differential Revision: https://reviews.llvm.org/D26182

llvm-svn: 285703
This commit is contained in:
Andrey Churbanov 2016-11-01 16:19:04 +00:00
parent 1408bf7231
commit 51107e0abc
1 changed files with 2 additions and 2 deletions
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4
openmp/runtime/src/kmp_tasking.c
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@ -1801,8 +1801,8 @@ __kmp_steal_task( kmp_info_t *victim, kmp_int32 gtid, kmp_task_team_t *task_team
parent = parent->td_parent; // check generation up to the level of the current task
KMP_DEBUG_ASSERT(parent != NULL);
}
if ( parent != current && (taskdata->td_flags.tiedness == TASK_TIED) ) { // untied is always allowed to be stolen
// If the tail task is not a child, then no other childs can appear in the deque (?).
if ( parent != current ) {
// If the tail task is not a descendant of the current task then do not steal it.
__kmp_release_bootstrap_lock( & victim_td -> td.td_deque_lock );
KA_TRACE(10, ("__kmp_steal_task(exit #2): T#%d could not steal from T#%d: task_team=%p "
"ntasks=%d head=%u tail=%u\n",