[OMPT] Fix unsafe initialization of ompt_data_t objects.

[hbae]

Summary

Initializing an ompt_data_t object using the pointer union member is potentially unsafe in 32-bit programs.
This change fixes the issue by using the constant, ompt_data_none.

[protze.joachim]

LGTM

openmp/trunk/runtime/src/kmp_runtime.cpp

if (this_thr->th.th_current_task->td_icvs.proc_bind == proc_bind_false) {
     // of proc-bind-var for this parallel region.
     proc_bind = this_thr->th.th_current_task->td_icvs.proc_bind;
   }
   // Reset for next parallel region
   this_thr->th.th_set_proc_bind = proc_bind_default;
 #endif /* OMP_40_ENABLED */
 
 #if OMPT_SUPPORT
-  ompt_data_t ompt_parallel_data;
-  ompt_parallel_data.ptr = NULL;
+  ompt_data_t ompt_parallel_data = ompt_data_none;
   ompt_data_t *implicit_task_data;
   void *codeptr = OMPT_LOAD_RETURN_ADDRESS(global_tid);
   if (ompt_enabled.enabled &&
       this_thr->th.ompt_thread_info.state != omp_state_overhead) {
 
     ompt_task_info_t *parent_task_info;
     parent_task_info = OMPT_CUR_TASK_INFO(this_thr);
 
#endif
     parent_team = master_th->th.th_team;
     master_tid = master_th->th.th_info.ds.ds_tid;
     master_this_cons = master_th->th.th_local.this_construct;
     root = master_th->th.th_root;
     master_active = root->r.r_active;
     master_set_numthreads = master_th->th.th_set_nproc;
 
 #if OMPT_SUPPORT
-    ompt_data_t ompt_parallel_data;
-    ompt_parallel_data.ptr = NULL;
+    ompt_data_t ompt_parallel_data = ompt_data_none;
     ompt_data_t *parent_task_data;
     omp_frame_t *ompt_frame;
     ompt_data_t *implicit_task_data;
     void *return_address = NULL;
 
     if (ompt_enabled.enabled) {
       __ompt_get_task_info_internal(0, NULL, &parent_task_data, &ompt_frame,
                                     NULL, NULL);
if (root->r.r_uber_thread) {
     root_thread = root->r.r_uber_thread;
   } else {
     root_thread = (kmp_info_t *)__kmp_allocate(sizeof(kmp_info_t));
     if (__kmp_storage_map) {
       __kmp_print_thread_storage_map(root_thread, gtid);
     }
     root_thread->th.th_info.ds.ds_gtid = gtid;
 #if OMPT_SUPPORT
-    root_thread->th.ompt_thread_info.thread_data.ptr = NULL;
+    root_thread->th.ompt_thread_info.thread_data = ompt_data_none;
 #endif
     root_thread->th.th_root = root;
     if (__kmp_env_consistency_check) {
       root_thread->th.th_cons = __kmp_allocate_cons_stack(gtid);
     }
 #if USE_FAST_MEMORY
     __kmp_initialize_fast_memory(root_thread);
 #endif /* USE_FAST_MEMORY */
void *__kmp_launch_thread(kmp_info_t *this_thr) {
   if (__kmp_env_consistency_check) {
     this_thr->th.th_cons = __kmp_allocate_cons_stack(gtid); // ATT: Memory leak?
   }
 
 #if OMPT_SUPPORT
   ompt_data_t *thread_data;
   if (ompt_enabled.enabled) {
     thread_data = &(this_thr->th.ompt_thread_info.thread_data);
-    thread_data->ptr = NULL;
+    *thread_data = ompt_data_none;
 
     this_thr->th.ompt_thread_info.state = omp_state_overhead;
     this_thr->th.ompt_thread_info.wait_id = 0;
     this_thr->th.ompt_thread_info.idle_frame = OMPT_GET_FRAME_ADDRESS(0);
     if (ompt_enabled.ompt_callback_thread_begin) {
       ompt_callbacks.ompt_callback(ompt_callback_thread_begin)(
           ompt_thread_worker, thread_data);
     }