Bug fix for hang when tasks used in nested parallel
Bug fix for hang when omp task and nested parallelism used together.
Still some problem remains with task state saving/restoring, but
user's case works fine now. All tasking unit tests passed as well.
Patch by Andrey Churbanov
Differential Revision: http://reviews.llvm.org/D21558
llvm-svn: 273297
diff --git a/openmp/runtime/src/kmp_runtime.c b/openmp/runtime/src/kmp_runtime.c
index 446dccb..55d080b 100644
--- a/openmp/runtime/src/kmp_runtime.c
+++ b/openmp/runtime/src/kmp_runtime.c
@@ -1459,8 +1459,8 @@
// Nested level will be an index in the nested nthreads array
level = parent_team->t.t_level;
-#if OMP_40_ENABLED
active_level = parent_team->t.t_active_level; // is used to launch non-serial teams even if nested is not allowed
+#if OMP_40_ENABLED
teams_level = master_th->th.th_teams_level; // needed to check nesting inside the teams
#endif
#if KMP_NESTED_HOT_TEAMS
@@ -2051,7 +2051,7 @@
__kmp_gtid_from_thread( master_th ), master_th->th.th_task_team,
parent_team, team->t.t_task_team[master_th->th.th_task_state], team ) );
- if ( level || master_th->th.th_task_team ) {
+ if ( active_level || master_th->th.th_task_team ) {
// Take a memo of master's task_state
KMP_DEBUG_ASSERT(master_th->th.th_task_state_memo_stack);
if (master_th->th.th_task_state_top >= master_th->th.th_task_state_stack_sz) { // increase size
@@ -2074,7 +2074,7 @@
master_th->th.th_task_state_memo_stack[master_th->th.th_task_state_top] = master_th->th.th_task_state;
master_th->th.th_task_state_top++;
#if KMP_NESTED_HOT_TEAMS
- if (team == master_th->th.th_hot_teams[level].hot_team) { // Restore master's nested state if nested hot team
+ if (team == master_th->th.th_hot_teams[active_level].hot_team) { // Restore master's nested state if nested hot team
master_th->th.th_task_state = master_th->th.th_task_state_memo_stack[master_th->th.th_task_state_top];
}
else {
diff --git a/openmp/runtime/test/tasking/nested_parallel_tasking.c b/openmp/runtime/test/tasking/nested_parallel_tasking.c
new file mode 100644
index 0000000..4374d6e
--- /dev/null
+++ b/openmp/runtime/test/tasking/nested_parallel_tasking.c
@@ -0,0 +1,32 @@
+// RUN: %libomp-compile-and-run
+#include <stdio.h>
+#include <omp.h>
+
+/*
+ * This test would hang when level instead of active level
+ * used to push task state.
+ */
+
+int main()
+{
+ // If num_threads is changed to a value greater than 1, then the test passes
+ #pragma omp parallel num_threads(1)
+ {
+ #pragma omp parallel
+ printf("Hello World from thread %d\n", omp_get_thread_num());
+ }
+
+ printf("omp_num_threads: %d\n", omp_get_max_threads());
+
+ #pragma omp parallel
+ {
+ #pragma omp master
+ #pragma omp task default(none)
+ {
+ printf("%d is executing this task\n", omp_get_thread_num());
+ }
+ }
+
+ printf("pass\n");
+ return 0;
+}