Reduce overhead of OMPT

[jmellorcrummey]

Summary

Avoid computing state needed only by OMPT unless the ompt_enabled flag is set.

Properly handle a corner case in OMPT where team == NULL.

[Hahnfeld]

LGTM. The change for __kmpc_for_static_fini may be applied to much more functions. I don't know whether this is relevant for the performance or the compiler is smart enough...

[jlpeyton]

LGTM as well.

openmp/trunk/runtime/src/kmp_csupport.c

 Mark the end of a statically scheduled loop.
 */
 void
 __kmpc_for_static_fini( ident_t *loc, kmp_int32 global_tid )
 {
     KE_TRACE( 10, ("__kmpc_for_static_fini called T#%d\n", global_tid));
 
 #if OMPT_SUPPORT && OMPT_TRACE
-    kmp_info_t *this_thr        = __kmp_threads[ global_tid ];
-    kmp_team_t *team            = this_thr -> th.th_team;
+    if (ompt_enabled &&
+        ompt_callbacks.ompt_callback(ompt_event_loop_end)) {
+        kmp_info_t *this_thr = __kmp_threads[ global_tid ];
+        kmp_team_t *team     = this_thr -> th.th_team;
         int tid = __kmp_tid_from_gtid( global_tid );
 
-    if (ompt_enabled &&
-        ompt_callbacks.ompt_callback(ompt_event_loop_end)) {
         ompt_callbacks.ompt_callback(ompt_event_loop_end)(
             team->t.ompt_team_info.parallel_id,
             team->t.t_implicit_task_taskdata[tid].ompt_task_info.task_id);
     }
 #endif
 
     if ( __kmp_env_consistency_check )
      __kmp_pop_workshare( global_tid, ct_pdo, loc );

openmp/trunk/runtime/src/kmp_sched.cpp

) {
     register kmp_int32   gtid = global_tid;
     register kmp_uint32  tid;
     register kmp_uint32  nth;
     register UT          trip_count;
     register kmp_team_t *team;
     register kmp_info_t *th = __kmp_threads[ gtid ];
 
 #if OMPT_SUPPORT && OMPT_TRACE
-    ompt_team_info_t *team_info = __ompt_get_teaminfo(0, NULL);
-    ompt_task_info_t *task_info = __ompt_get_taskinfo(0);
+    ompt_team_info_t *team_info = NULL; 
+    ompt_task_info_t *task_info = NULL; 
+
+    if (ompt_enabled) {
+        // Only fully initialize variables needed by OMPT if OMPT is enabled.
+        team_info = __ompt_get_teaminfo(0, NULL);
+        task_info = __ompt_get_taskinfo(0);
+    }
 #endif
 
     KMP_DEBUG_ASSERT( plastiter && plower && pupper && pstride );
     KE_TRACE( 10, ("__kmpc_for_static_init called (%d)\n", global_tid));
     #ifdef KMP_DEBUG
     {
         const char * buff;
         // create format specifiers before the debug output

openmp/trunk/runtime/src/ompt-specific.c

 
 ompt_team_info_t *
 __ompt_get_teaminfo(int depth, int *size)
 {
     kmp_info_t *thr = ompt_get_thread();
 
     if (thr) {
         kmp_team *team = thr->th.th_team;
+        if (team == NULL) return NULL;
+
         ompt_lw_taskteam_t *lwt = LWT_FROM_TEAM(team);
 
         while(depth > 0) {
             // next lightweight team (if any)
             if (lwt) lwt = lwt->parent;
 
             // next heavyweight team (if any) after
             // lightweight teams are exhausted