[OpenMP] libomp: Fix crash in case application send us negative thread_limit value

[AndreyChurbanov]

Summary

Fix crash in case non-conforming application send us negative thread_limit value.

Issue warning and continue with default value instead of crash silently.

[tlwilmar]

LGTM

openmp/runtime/src/i18n/en_US.txt

 FailedToCreateTeam           "Failed to create teams between lower bound (%1$d) and upper bound (%2$d)."
 AffHWSubsetManyGeneric       "KMP_HW_SUBSET ignored: %1$s: too many requested."
 AffHWSubsetNotExistGeneric   "KMP_HW_SUBSET ignored: %1$s: level not detected in machine topology."
 AffHWSubsetEqvLayers         "KMP_HW_SUBSET ignored: %1$s, %2$s: layers are equivalent, please only specify one."
 AffHWSubsetOutOfOrder        "KMP_HW_SUBSET ignored: %1$s layer should come after %2$s."
 AffEqualTopologyTypes        "%1$s: topology layer \"%2$s\" is equivalent to \"%3$s\"."
 AffGranTooCoarseProcGroup    "%1$s: granularity=%2$s is too coarse, setting granularity=group."
 StgDeprecatedValue           "%1$s: \"%2$s\" value is deprecated. Please use \"%3$s\" instead."
+NumTeamsNotPositive          "num_teams value must be positive, it is %1$d, using %2$d instead."
 
 # --------------------------------------------------------------------------------------------------
 -*- HINTS -*-
 # --------------------------------------------------------------------------------------------------
 
 # Hints. Hint may be printed after a message. Usually it is longer explanation text or suggestion.
 # To maintain hint numbers (they are visible to customers), add new hints to the end.
 

openmp/runtime/src/kmp_runtime.cpp

if (num_threads == 0) {
     } // prevent team size to exceed thread-limit-var
     if (num_teams * num_threads > __kmp_teams_max_nth) {
       num_threads = __kmp_teams_max_nth / num_teams;
     }
     if (num_threads == 0) {
       num_threads = 1;
     }
   } else {
+    if (num_threads < 0) {
+      __kmp_msg(kmp_ms_warning, KMP_MSG(CantFormThrTeam, num_threads, 1),
+                __kmp_msg_null);
+      num_threads = 1;
+    }
     // This thread will be the primary thread of the league primary threads
     // Store new thread limit; old limit is saved in th_cg_roots list
     thr->th.th_current_task->td_icvs.thread_limit = num_threads;
     // num_threads = min(num_threads, nthreads-var)
     if (num_threads > __kmp_dflt_team_nth) {
       num_threads = __kmp_dflt_team_nth; // honor nthreads-var ICV
     }
     if (num_teams * num_threads > __kmp_teams_max_nth) {
static void __kmp_push_thread_limit(kmp_info_t *thr, int num_teams,
   thr->th.th_teams_size.nth = num_threads;
 }
 
 /* this sets the requested number of teams for the teams region and/or
    the number of threads for the next parallel region encountered  */
 void __kmp_push_num_teams(ident_t *id, int gtid, int num_teams,
                           int num_threads) {
   kmp_info_t *thr = __kmp_threads[gtid];
-  KMP_DEBUG_ASSERT(num_teams >= 0);
-  KMP_DEBUG_ASSERT(num_threads >= 0);
-
+  if (num_teams < 0) {
+    // OpenMP specification requires requested values to be positive,
+    // but people can send us any value, so we'd better check
+    __kmp_msg(kmp_ms_warning, KMP_MSG(NumTeamsNotPositive, num_teams, 1),
+              __kmp_msg_null);
+    num_teams = 1;
+  }
   if (num_teams == 0) {
     if (__kmp_nteams > 0) {
       num_teams = __kmp_nteams;
     } else {
       num_teams = 1; // default number of teams is 1.
     }
   }
   if (num_teams > __kmp_teams_max_nth) { // if too many teams requested?
if (num_teams > __kmp_teams_max_nth) {
                   KMP_MSG(CantFormThrTeam, num_teams, __kmp_teams_max_nth),
                   KMP_HNT(Unset_ALL_THREADS), __kmp_msg_null);
       }
       num_teams = __kmp_teams_max_nth;
     }
   } else if (num_teams_lb == num_teams_ub) { // requires exact number of teams
     num_teams = num_teams_ub;
   } else { // num_teams_lb <= num_teams <= num_teams_ub
-    if (num_threads == 0) {
+    if (num_threads <= 0) {
       if (num_teams_ub > __kmp_teams_max_nth) {
         num_teams = num_teams_lb;
       } else {
         num_teams = num_teams_ub;
       }
     } else {
       num_teams = (num_threads > __kmp_teams_max_nth)
                       ? num_teams