[OpenMP] Clean up for hidden helper task

This patch makes some clean up for code of hidden helper task.

Reviewed By: protze.joachim

Differential Revision: https://reviews.llvm.org/D107008

Author: shiltian

openmp/runtime/src/kmp.h

@@ -2421,13 +2421,6 @@ struct kmp_taskdata { /* aligned during dynamic allocation       */
   kmp_depnode_t
       *td_depnode; // Pointer to graph node if this task has dependencies
   kmp_task_team_t *td_task_team;
-  // The global thread id of the encountering thread. We need it because when a
-  // regular task depends on a hidden helper task, and the hidden helper task
-  // is finished on a hidden helper thread, it will call __kmp_release_deps to
-  // release all dependences. If now the task is a regular task, we need to pass
-  // the encountering gtid such that the task will be picked up and executed by
-  // its encountering team instead of hidden helper team.
-  kmp_int32 encountering_gtid;
   size_t td_size_alloc; // Size of task structure, including shareds etc.
 #if defined(KMP_GOMP_COMPAT)
   // 4 or 8 byte integers for the loop bounds in GOMP_taskloop

openmp/runtime/src/kmp_taskdeps.h

@@ -144,9 +144,10 @@ static inline void __kmp_release_deps(kmp_int32 gtid, kmp_taskdata_t *task) {
           // encountering thread's queue; otherwise, it can be pushed to its own
           // queue.
           if (!next_taskdata->td_flags.hidden_helper) {
-            __kmpc_give_task(
-                successor->dn.task,
-                __kmp_tid_from_gtid(next_taskdata->encountering_gtid));
+            kmp_int32 encountering_gtid =
+                next_taskdata->td_alloc_thread->th.th_info.ds.ds_gtid;
+            kmp_int32 encountering_tid = __kmp_tid_from_gtid(encountering_gtid);
+            __kmpc_give_task(successor->dn.task, encountering_tid);
           } else {
             __kmp_omp_task(gtid, successor->dn.task, false);
           }

openmp/runtime/src/kmp_tasking.cpp

@@ -1192,7 +1192,6 @@ kmp_task_t *__kmp_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
   kmp_task_t *task;
   kmp_taskdata_t *taskdata;
   kmp_info_t *thread = __kmp_threads[gtid];
-  kmp_info_t *encountering_thread = thread;
   kmp_team_t *team = thread->th.th_team;
   kmp_taskdata_t *parent_task = thread->th.th_current_task;
   size_t shareds_offset;
@@ -1204,15 +1203,6 @@ kmp_task_t *__kmp_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
     if (__kmp_enable_hidden_helper) {
       if (!TCR_4(__kmp_init_hidden_helper))
         __kmp_hidden_helper_initialize();
-
-      // For a hidden helper task encountered by a regular thread, we will push
-      // the task to the (gtid%__kmp_hidden_helper_threads_num)-th hidden helper
-      // thread.
-      if (!KMP_HIDDEN_HELPER_THREAD(gtid)) {
-        thread = __kmp_threads[KMP_GTID_TO_SHADOW_GTID(gtid)];
-        // We don't change the parent-child relation for hidden helper task as
-        // we need that to do per-task-region synchronization.
-      }
     } else {
       // If the hidden helper task is not enabled, reset the flag to FALSE.
       flags->hidden_helper = FALSE;
@@ -1235,8 +1225,7 @@ kmp_task_t *__kmp_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
     // Untied task encountered causes the TSC algorithm to check entire deque of
     // the victim thread. If no untied task encountered, then checking the head
     // of the deque should be enough.
-    KMP_CHECK_UPDATE(
-        encountering_thread->th.th_task_team->tt.tt_untied_task_encountered, 1);
+    KMP_CHECK_UPDATE(thread->th.th_task_team->tt.tt_untied_task_encountered, 1);
   }
 
   // Detachable tasks are not proxy tasks yet but could be in the future. Doing
@@ -1250,32 +1239,30 @@ kmp_task_t *__kmp_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
     }
     /* are we running in a sequential parallel or tskm_immediate_exec... we need
        tasking support enabled */
-    if ((encountering_thread->th.th_task_team) == NULL) {
+    if ((thread->th.th_task_team) == NULL) {
       /* This should only happen if the team is serialized
           setup a task team and propagate it to the thread */
       KMP_DEBUG_ASSERT(team->t.t_serialized);
       KA_TRACE(30,
                ("T#%d creating task team in __kmp_task_alloc for proxy task\n",
                 gtid));
-      __kmp_task_team_setup(
-          encountering_thread, team,
-          1); // 1 indicates setup the current team regardless of nthreads
-      encountering_thread->th.th_task_team =
-          team->t.t_task_team[encountering_thread->th.th_task_state];
+      // 1 indicates setup the current team regardless of nthreads
+      __kmp_task_team_setup(thread, team, 1);
+      thread->th.th_task_team = team->t.t_task_team[thread->th.th_task_state];
     }
-    kmp_task_team_t *task_team = encountering_thread->th.th_task_team;
+    kmp_task_team_t *task_team = thread->th.th_task_team;
 
     /* tasking must be enabled now as the task might not be pushed */
     if (!KMP_TASKING_ENABLED(task_team)) {
       KA_TRACE(
           30,
           ("T#%d enabling tasking in __kmp_task_alloc for proxy task\n", gtid));
-      __kmp_enable_tasking(task_team, encountering_thread);
-      kmp_int32 tid = encountering_thread->th.th_info.ds.ds_tid;
+      __kmp_enable_tasking(task_team, thread);
+      kmp_int32 tid = thread->th.th_info.ds.ds_tid;
       kmp_thread_data_t *thread_data = &task_team->tt.tt_threads_data[tid];
       // No lock needed since only owner can allocate
       if (thread_data->td.td_deque == NULL) {
-        __kmp_alloc_task_deque(encountering_thread, thread_data);
+        __kmp_alloc_task_deque(thread, thread_data);
       }
     }
 
@@ -1300,11 +1287,11 @@ kmp_task_t *__kmp_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
 
   // Avoid double allocation here by combining shareds with taskdata
 #if USE_FAST_MEMORY
-  taskdata = (kmp_taskdata_t *)__kmp_fast_allocate(
-      encountering_thread, shareds_offset + sizeof_shareds);
+  taskdata = (kmp_taskdata_t *)__kmp_fast_allocate(thread, shareds_offset +
+                                                               sizeof_shareds);
 #else /* ! USE_FAST_MEMORY */
-  taskdata = (kmp_taskdata_t *)__kmp_thread_malloc(
-      encountering_thread, shareds_offset + sizeof_shareds);
+  taskdata = (kmp_taskdata_t *)__kmp_thread_malloc(thread, shareds_offset +
+                                                               sizeof_shareds);
 #endif /* USE_FAST_MEMORY */
 
   task = KMP_TASKDATA_TO_TASK(taskdata);
@@ -1331,7 +1318,7 @@ kmp_task_t *__kmp_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
 
   taskdata->td_task_id = KMP_GEN_TASK_ID();
   taskdata->td_team = thread->th.th_team;
-  taskdata->td_alloc_thread = encountering_thread;
+  taskdata->td_alloc_thread = thread;
   taskdata->td_parent = parent_task;
   taskdata->td_level = parent_task->td_level + 1; // increment nesting level
   KMP_ATOMIC_ST_RLX(&taskdata->td_untied_count, 0);
@@ -1345,10 +1332,16 @@ kmp_task_t *__kmp_task_alloc(ident_t *loc_ref, kmp_int32 gtid,
     copy_icvs(&taskdata->td_icvs, &taskdata->td_parent->td_icvs);
 
   taskdata->td_flags = *flags;
-  taskdata->encountering_gtid = gtid;
   taskdata->td_task_team = thread->th.th_task_team;
   taskdata->td_size_alloc = shareds_offset + sizeof_shareds;
   taskdata->td_flags.tasktype = TASK_EXPLICIT;
+  // If it is hidden helper task, we need to set the team and task team
+  // correspondingly.
+  if (flags->hidden_helper) {
+    kmp_info_t *shadow_thread = __kmp_threads[KMP_GTID_TO_SHADOW_GTID(gtid)];
+    taskdata->td_team = shadow_thread->th.th_team;
+    taskdata->td_task_team = shadow_thread->th.th_task_team;
+  }
 
   // GEH - TODO: fix this to copy parent task's value of tasking_ser flag
   taskdata->td_flags.tasking_ser = (__kmp_tasking_mode == tskm_immediate_exec);
@@ -3957,7 +3950,7 @@ void __kmpc_give_task(kmp_task_t *ptask, kmp_int32 start = 0) {
 
   // This should be similar to start_k = __kmp_get_random( thread ) % nthreads
   // but we cannot use __kmp_get_random here
-  kmp_int32 start_k = start;
+  kmp_int32 start_k = start % nthreads;
   kmp_int32 pass = 1;
   kmp_int32 k = start_k;