[OpenMP][libomp] Fix disabled affinity

[jlpeyton]

Summary

Fix setting affinity type and topology method when affinity is disabled
and fix places that were not taking into account that affinity can be
explicitly disabled by putting proper KMP_AFFINITY_CAPABLE() check.

[jlpeyton]

@mgorny , This patch should fix the issues you were seeing after https://reviews.llvm.org/D135113. Can you confirm?

[mgorny]

Can't say much about the code but I can confirm that this makes the tests pass for me.

openmp/runtime/src/kmp.h

static inline void __kmp_assign_root_init_mask() {
   int gtid = __kmp_entry_gtid();
   kmp_root_t *r = __kmp_threads[gtid]->th.th_root;
   if (r->r.r_uber_thread == __kmp_threads[gtid] && !r->r.r_affinity_assigned) {
     __kmp_affinity_set_init_mask(gtid, TRUE);
     r->r.r_affinity_assigned = TRUE;
   }
 }
 static inline void __kmp_reset_root_init_mask(int gtid) {
+  if (!KMP_AFFINITY_CAPABLE())
+    return;
   kmp_info_t *th = __kmp_threads[gtid];
   kmp_root_t *r = th->th.th_root;
   if (r->r.r_uber_thread == th && r->r.r_affinity_assigned) {
     __kmp_set_system_affinity(__kmp_affin_origMask, FALSE);
     KMP_CPU_COPY(th->th.th_affin_mask, __kmp_affin_origMask);
     r->r.r_affinity_assigned = FALSE;
   }
 }

openmp/runtime/src/kmp_affinity.cpp

 
 void kmp_topology_t::print(const char *env_var) const {
   kmp_str_buf_t buf;
   int print_types_depth;
   __kmp_str_buf_init(&buf);
   kmp_hw_t print_types[KMP_HW_LAST + 2];
 
   // Num Available Threads
+  if (num_hw_threads) {
     KMP_INFORM(AvailableOSProc, env_var, num_hw_threads);
+  } else {
+    KMP_INFORM(AvailableOSProc, env_var, __kmp_xproc);
+  }
 
   // Uniform or not
   if (is_uniform()) {
     KMP_INFORM(Uniform, env_var);
   } else {
     KMP_INFORM(NonUniform, env_var);
   }
 
#endif // KMP_OS_LINUX && USE_SYSFS_INFO
       }
       if (threadInfo[0][pkgIdIndex] == UINT_MAX) {
         CLEANUP_THREAD_INFO;
         *msg_id = kmp_i18n_str_MissingPhysicalIDField;
         return false;
       }
 
       // Skip this proc if it is not included in the machine model.
-      if (!KMP_CPU_ISSET(threadInfo[num_avail][osIdIndex],
+      if (KMP_AFFINITY_CAPABLE() &&
+          !KMP_CPU_ISSET(threadInfo[num_avail][osIdIndex],
                          __kmp_affin_fullMask)) {
         INIT_PROC_INFO(threadInfo[num_avail]);
         continue;
       }
 
       // We have a successful parse of this proc's info.
       // Increment the counter, and prepare for the next proc.
       num_avail++;
if (affinity->masks != NULL)
       KMP_CPU_FREE_ARRAY(affinity->masks, affinity->num_masks);
     if (affinity->os_id_masks != NULL)
       KMP_CPU_FREE_ARRAY(affinity->os_id_masks, affinity->num_os_id_masks);
     if (affinity->proclist != NULL)
       __kmp_free(affinity->proclist);
     *affinity = KMP_AFFINITY_INIT(affinity->env_var);
   }
   if (__kmp_affin_origMask != NULL) {
+    if (KMP_AFFINITY_CAPABLE()) {
+      __kmp_set_system_affinity(__kmp_affin_origMask, FALSE);
+    }
     KMP_CPU_FREE(__kmp_affin_origMask);
     __kmp_affin_origMask = NULL;
   }
   __kmp_affinity_num_places = 0;
   if (procarr != NULL) {
     __kmp_free(procarr);
     procarr = NULL;
   }

openmp/runtime/src/kmp_settings.cpp

#endif
           {
             __kmp_hh_affinity.gran = KMP_HW_CORE;
           }
         }
         if (__kmp_affinity_top_method == affinity_top_method_default) {
           __kmp_affinity_top_method = affinity_top_method_all;
         }
       }
+    } else {
+      // If affinity is disabled, then still need to assign topology method
+      // to attempt machine detection and affinity types
+      if (__kmp_affinity_top_method == affinity_top_method_default)
+        __kmp_affinity_top_method = affinity_top_method_all;
+      if (__kmp_affinity.type == affinity_default)
+        __kmp_affinity.type = affinity_disabled;
+      if (__kmp_hh_affinity.type == affinity_default)
+        __kmp_hh_affinity.type = affinity_disabled;
     }
 
 #ifdef KMP_DEBUG
     for (const kmp_affinity_t *affinity : __kmp_affinities)
       __kmp_print_affinity_settings(affinity);
     KMP_DEBUG_ASSERT(__kmp_nested_proc_bind.bind_types[0] != proc_bind_default);
     K_DIAG(1, ("__kmp_nested_proc_bind.bind_types[0] == %d\n",
                __kmp_nested_proc_bind.bind_types[0]));

openmp/runtime/test/affinity/disabled.c

+// RUN: %libomp-compile
+// RUN: env KMP_AFFINITY=disabled %libomp-run
+// RUN: env KMP_AFFINITY=disabled,reset %libomp-run
+// REQUIRES: affinity
+#include <stdio.h>
+#include <stdlib.h>
+#include <omp.h>
+
+int main() {
+  int nthreads, correct_value;;
+  int a = 0;
+  #pragma omp parallel reduction(+: a)
+  {
+    a += omp_get_thread_num();
+    #pragma omp single
+    nthreads = omp_get_num_threads();
+  }
+  correct_value = nthreads * (nthreads - 1) / 2;
+  if (a != correct_value) {
+    printf("Incorrect value: %d should be %d\n", a, correct_value);
+    return EXIT_FAILURE;
+  }
+  return EXIT_SUCCESS;
+}
+