Fix initialization of th_task_state on each thread on expanding hot teams.

The th_task_state was initialized from the master thread's value, or
from its memo stack, but this causes problems because neither of those
may have the right value at the right time. However, other threads in
the team are guaranteed to have the right values, so we change the
initialize the new threads' th_task_state from the th_task_state of
the last of the older threads in the hot team.

Differential Revision: https://reviews.llvm.org/D142247
Fix #56307.

diff --git a/openmp/runtime/src/kmp_runtime.cpp b/openmp/runtime/src/kmp_runtime.cpp
index 7393dba..f9fd0ca 100644 (file)
--- a/openmp/runtime/src/kmp_runtime.cpp
+++ b/openmp/runtime/src/kmp_runtime.cpp
@@ -5445,21 +5445,10 @@ __kmp_allocate_team(kmp_root_t *root, int new_nproc, int max_nproc,
         __kmp_initialize_info(team->t.t_threads[f], team, f,
                               __kmp_gtid_from_tid(f, team));
 
-      if (level) { // set th_task_state for new threads in nested hot team
-        // __kmp_initialize_info() no longer zeroes th_task_state, so we should
-        // only need to set the th_task_state for the new threads. th_task_state
-        // for primary thread will not be accurate until after this in
-        // __kmp_fork_call(), so we look to the primary thread's memo_stack to
-        // get the correct value.
-        for (f = old_nproc; f < team->t.t_nproc; ++f)
-          team->t.t_threads[f]->th.th_task_state =
-              team->t.t_threads[0]->th.th_task_state_memo_stack[level];
-      } else { // set th_task_state for new threads in non-nested hot team
-        // copy primary thread's state
-        kmp_uint8 old_state = team->t.t_threads[0]->th.th_task_state;
-        for (f = old_nproc; f < team->t.t_nproc; ++f)
-          team->t.t_threads[f]->th.th_task_state = old_state;
-      }
+      // set th_task_state for new threads in hot team with older thread's state
+      kmp_uint8 old_state = team->t.t_threads[old_nproc - 1]->th.th_task_state;
+      for (f = old_nproc; f < team->t.t_nproc; ++f)
+        team->t.t_threads[f]->th.th_task_state = old_state;
 
 #ifdef KMP_DEBUG
       for (f = 0; f < team->t.t_nproc; ++f) {