[OpenMP] libomp cleanup: check presence of hwloc objects CORE, PACKAGE

hwloc documentation guarantees the only object that is always present
in the topology is PU. We can check the presence of other objects
in the topology, just in case.

Differential Revision: https://reviews.llvm.org/D84065

Author: AndreyChurbanov

openmp/runtime/src/kmp_affinity.cpp

@@ -577,11 +577,17 @@ static int __kmp_affinity_create_hwloc_map(AddrUnsPair **address2os,
     // Hack to try and infer the machine topology using only the data
     // available from cpuid on the current thread, and __kmp_xproc.
     KMP_ASSERT(__kmp_affinity_type == affinity_none);
-
-    nCoresPerPkg = __kmp_hwloc_get_nobjs_under_obj(
-        hwloc_get_obj_by_type(tp, HWLOC_OBJ_PACKAGE, 0), HWLOC_OBJ_CORE);
-    __kmp_nThreadsPerCore = __kmp_hwloc_get_nobjs_under_obj(
-        hwloc_get_obj_by_type(tp, HWLOC_OBJ_CORE, 0), HWLOC_OBJ_PU);
+    // hwloc only guarantees existance of PU object, so check PACKAGE and CORE
+    hwloc_obj_t o = hwloc_get_obj_by_type(tp, HWLOC_OBJ_PACKAGE, 0);
+    if (o != NULL)
+      nCoresPerPkg = __kmp_hwloc_get_nobjs_under_obj(o, HWLOC_OBJ_CORE);
+    else
+      nCoresPerPkg = 1; // no PACKAGE found
+    o = hwloc_get_obj_by_type(tp, HWLOC_OBJ_CORE, 0);
+    if (o != NULL)
+      __kmp_nThreadsPerCore = __kmp_hwloc_get_nobjs_under_obj(o, HWLOC_OBJ_PU);
+    else
+      __kmp_nThreadsPerCore = 1; // no CORE found
     __kmp_ncores = __kmp_xproc / __kmp_nThreadsPerCore;
     nPackages = (__kmp_xproc + nCoresPerPkg - 1) / nCoresPerPkg;
     if (__kmp_affinity_verbose) {