<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/94260>94260</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [OpenMP] Debug assert hit with nesting parallels
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          mikaoP
      </td>
    </tr>
</table>

<pre>
    ```cpp
//  This is a simplification of task_teams_stress_test.cpp test
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <omp.h>

// The number of times to run each test
#define NTIMES 2

// Every thread creates a single "increment" task
void test_tasks() {
  for (int i = 0; i < 100; ++i)
  #pragma omp task
 {
  int tid = omp_get_thread_num();
  }
}

// Testing single level of parallelism with increment tasks
void test_base(int nthreads) {
#ifdef VERBOSE
#pragma omp master
  printf(" test_base(%d)\n", nthreads);
#endif
#pragma omp parallel num_threads(nthreads)
  { test_tasks(); }
}

// Testing nested parallel with increment tasks
// first = nthreads of outer parallel
// second = nthreads of nested parallel
void test_nest(int first, int second) {
#ifdef VERBOSE
#pragma omp master
  printf("   test_nest(%d, %d)\n", first, second);
#endif
#pragma omp parallel num_threads(first)
  {
  for (int i = 0; i < 100; ++i)
  #pragma omp task
  {
  int tid = omp_get_thread_num();
  }
 test_base(second);
  }
}

template <typename... Args>
void run_ntimes(int n, void (*func)(Args...), Args... args) {
  for (int i = 0; i < n; ++i) {
    func(args...);
  }
}

int main() {
 omp_set_max_active_levels(5);

  run_ntimes(NTIMES, test_nest, 4, 3);
  run_ntimes(NTIMES, test_nest, 2, 1);

 printf("PASS\n");
  return EXIT_SUCCESS;
}
```
`Assertion failure at kmp_tasking.cpp(3238): victim_tid < task_team->tt.tt_nproc.`
`clang++ -fopenmp t1.cpp -o t1 && while taskset -c 0-1 env KMP_USE_YIELD=0 ./t1 || break; do date; done`
Aparently it is necessary `KMP_USE_YIELD=0`. I've not managed how to reproduce it with 1 or 2. Also less cpus than threads is needed.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy0Vl1v6zYM_TXKCxHDkfP5kId8FSi2u1ssvcP2ZMgWbWu1JUOi0_XfD5ITN7lttwK7A4pGCkMenkOKknBOlRpxzWZbNtuPREeVsetGPQnzMMqMfFmzedz_5W3L4j2LN4zfMX4H8FgpB8qBAKeatlaFygUpo8EUQMI9pYSicakji86lhI6ivG3BLy6BEqXzupMILNkJ59BSVLHk8J7ZkVTmn6y1yj40d1o5kh-aTdNe265ZPlYIumsytIGWatABGbCdBhR5dctGYqE0wi-P918OR-DvhDuc0L4AVRaFhNyiIOwF1GWNwDhXOrfYoCbGeVCxdz8ZJQNW6r9zjC8ZXwFbbHszQGEsML5UmkABS_YQs2QbljuYxGHD-JbxrWJ8dXFiPGmtKBsBpmmv0K4D-4ikZIhpmjYtkdI-_1R3TZ8IS4afs8X-THhY3MiJjpQuL4RrPGHthW2FFXWNtXINPCuqYNABesLfqZAJh2e6us_G3Qji61tILOC3w6_br8fXql_xbYQjtJfEW6s0FYEPv8FgfCY9x9lOM84Z310jDswZT1BLVbwHdCHnGykdfJfXYQb1tm-qHEr3OVU1OkL5ivexkmfHQllHobSXZHwxTEdohyg3Dg5zo-Ubj--Av6-WN5-rFRC9iH7TR_uRhYMbwL50O3hbwiGNIYX_UslztOsy_j_n8kcczJvmfkv_4yNM2LS1oDAx6aVFLRqMogg2tnTD8AxFt51OdZiVlzPqpQ6mkNem6HTuQfnSO0dRFDY7OO9A-JCfH3D6VsZrN4Aeaylegf6dqkdphNJv5qwX2iGljfgrFTmpE6Zhhnmis5suOiPcSNFfDJ7oVZfuYOr_JbeZfcYvdPLkHdTrI_GwOR6Hxr9BQOqshsPv94_p8dtudzgeX-MMclxu_2G7Cde0v-YLoerOIgiCp6YNI0vp0t_xjC8TnvQNuIGTykk1ad-ru9enwZglB6KIKNWtNXl0jZLXQpd9RWFcmBa1PwiT8IAYG6AJMD5nfA7Plaqxn2xIMM4hHk8A9Ql--vKQfjse0j_uDz_vWbKPIWL8zjsudmyxg8yiePJ9Iw1IQdgvNQ5ZbFphUVP9Aor8M0djjs4J-wJsHr-JzuZxBPeML04I2vju0aJECZV5Du8FbK2RXY4-WBjLEzAWeASb2hmo0TnI284BVULDZbIGVJQoo5FcJ3KVrMQI15PFZDFNZvGMj6r1fJov-UwulnGRr-bLlcwynIp5kec5FqLIRmrNYz6N53Hi_ZJJtFjIosBsKafJFOczzqYxNkLVUV2fmsjYcqSc63C9mvJ5PKpFhrUL70PONT5DMPpmmu1Hdu19xllXOjaNa-XIvUYhRXV4WH5tUX95YLM97DHrSugfelBdlNDn2-syXN2os_W6ImodS84XT6mo6rIoNw3jdx7i_DFurfkTc2L8LiTmGL_rEz-t-d8BAAD__7YmN34">