Fix for bug https://llvm.org/bugs/show_bug.cgi?id=30889

[AndreyChurbanov]

Summary

Assertion should not work on exit from OpenMP teams construct where task team field can be different in thread structure and in team structure. Added check that a thread does not exit the teams.

[grokos]

I am not an expert here and I'm not sure exactly how this works, but it seems to fix the problem.

One question though: The same assertion can be found throughout kmp_runtime.cpp, do other instances need this patching as well? E.g. line 2050, where there is a comment about a forthcoming patch that fixes the preconditions which spuriously make assertions to trigger.

runtime/src/kmp_runtime.cpp

2050–2051

What about here?

[grokos]

Ping.

[AndreyChurbanov]

runtime/src/kmp_runtime.cpp

2050–2051

This is a different problem related with inconsistent references to task team in thread and team structures. It was actually fixed by the commit r249711 (https://reviews.llvm.org/D13353).

I will submit separate patch to re-enable this assertion.

[omalyshe]

LGTM.

runtime/src/kmp_runtime.cpp

 #endif
 
     // Update the floating point rounding in the team if required.
     propagateFPControl(team);
 
     if ( __kmp_tasking_mode != tskm_immediate_exec ) {
         // Set master's task team to team's task team. Unless this is hot team, it should be NULL.
 #if 0
         // Patch out an assertion that trips while the runtime seems to operate correctly.
         // Avoiding the preconditions that cause the assertion to trip has been promised as a forthcoming patch.
         KMP_DEBUG_ASSERT(master_th->th.th_task_team == parent_team->t.t_task_team[master_th->th.th_task_state]);
 #endif
         KA_TRACE( 20, ( "__kmp_fork_call: Master T#%d pushing task_team %p / team %p, new task_team %p / team %p\n",
                       __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 ( active_level || master_th->th.th_task_team ) {
             // Take a memo of master's task_state

 
 #if OMPT_SUPPORT
     if (ompt_enabled) {
         master_th->th.ompt_thread_info.state = ompt_state_overhead;
     }
 #endif
 
 #if KMP_DEBUG
-    if ( __kmp_tasking_mode != tskm_immediate_exec ) {
+    if ( __kmp_tasking_mode != tskm_immediate_exec && !exit_teams) {
         KA_TRACE( 20, ( "__kmp_join_call: T#%d, old team = %p old task_team = %p, th_task_team = %p\n",
                          __kmp_gtid_from_thread( master_th ), team,
                          team->t.t_task_team[master_th->th.th_task_state], master_th->th.th_task_team) );
         KMP_DEBUG_ASSERT( master_th->th.th_task_team == team->t.t_task_team[master_th->th.th_task_state] );
     }
 #endif
 
     if( team->t.t_serialized ) {