[OpenMP] avoid segv for a lock that has already been destroyed

  This can happen in static destructors when called after the
  runtime is already shutdown (e.g., by ompt_finalize_tool). Even
  though it is technically an error to call omp_destroy_lock after
  shutdown, the application doesn't necessarily know that omp_destroy_lock
  was already called. This is safe becaues all indirect locks are
  destoryed in __kmp_cleanup_indirect_user_locks so the return
  value will always be valid or a nullptr, not garbage.

Author: lfmeadow

openmp/runtime/src/kmp_lock.cpp

@@ -3242,6 +3242,8 @@ static void __kmp_destroy_indirect_lock(kmp_dyna_lock_t *lock) {
   kmp_uint32 gtid = __kmp_entry_gtid();
   kmp_indirect_lock_t *l =
       __kmp_lookup_indirect_lock((void **)lock, "omp_destroy_lock");
+  if (l == nullptr)
+    return; // avoid segv if lock already destroyed
   KMP_I_LOCK_FUNC(l, destroy)(l->lock);
   kmp_indirect_locktag_t tag = l->type;
 

openmp/runtime/test/ompt/misc/lock_double_destroy.cpp

@@ -0,0 +1,40 @@
+// RUN: %libomp-cxx-compile-and-run | FileCheck %s
+// REQUIRES: ompt
+#include "callback.h"
+#include "omp_testsuite.h"
+
+// tests that the destructor doesn't segv even though
+// ompt_finalize_tool() destroys the lock
+struct myLock {
+  omp_lock_t lock;
+  myLock() { omp_init_lock(&lock); }
+  ~myLock() { omp_destroy_lock(&lock); }
+};
+
+myLock lock;
+
+int main() {
+  go_parallel_nthreads(2);
+
+  printf("Before ompt_finalize_tool\n");
+  ompt_finalize_tool();
+  printf("After ompt_finalize_tool\n");
+
+  return get_exit_value();
+}
+
+// CHECK: 0: NULL_POINTER=[[NULL:.*$]]
+// CHECK: {{^}}[[THREAD_ID:[0-9]+]]: ompt_event_thread_begin:
+// CHECK-SAME: thread_type=ompt_thread_initial=1
+
+// CHECK: {{^}}[[THREAD_ID]]: ompt_event_init_lock
+
+// CHECK: {{^}}[[THREAD_ID]]: ompt_event_parallel_begin
+// CHECK: {{^}}[[THREAD_ID]]: ompt_event_parallel_end
+
+// CHECK: {{^}}Before ompt_finalize_tool
+
+// CHECK: {{^}}[[THREAD_ID]]: ompt_event_thread_end: thread_id=[[THREAD_ID]]
+// CHECK: 0: ompt_event_runtime_shutdown
+
+// CHECK: {{^}}After ompt_finalize_tool