Use 'critical' reduction method when 'atomic' is not available but re…

…quested.

In case atomic reduction method is not available (the compiler can't generate
it) the assertion failure occurred if KMP_FORCE_REDUCTION=atomic was specified.
This change replaces the assertion with a warning and sets the reduction method
to the default one - 'critical'.

Patch by Olga Malysheva

Differential Revision: https://reviews.llvm.org/D23990

llvm-svn: 280519

openmp/runtime/src/i18n/en_US.txt

@@ -38,7 +38,7 @@ Language "English"
 Country  "USA"
 LangId   "1033"
 Version  "2"
-Revision "20160405"
+Revision "20160714"
 
 
 
@@ -410,6 +410,7 @@ AffIgnoringHwloc             "%1$s: Ignoring hwloc mechanism."
 AffHwlocErrorOccurred        "%1$s: Hwloc failed in %2$s. Relying on internal affinity mechanisms."
 EnvSerialWarn                "%1$s must be set prior to OpenMP runtime library initialization; ignored."
 EnvVarDeprecated             "%1$s variable deprecated, please use %2$s instead."
+RedMethodNotSupported        "KMP_FORCE_REDUCTION: %1$s method is not supported; using critical."
 
 
 # --------------------------------------------------------------------------------------------------

openmp/runtime/src/kmp_runtime.c

@@ -7585,27 +7585,34 @@ __kmp_determine_reduction_method( ident_t *loc, kmp_int32 global_tid,
     // method and stay with the unsynchronized method (empty_reduce_block)
     if( __kmp_force_reduction_method != reduction_method_not_defined && team_size != 1) {
 
-        PACKED_REDUCTION_METHOD_T forced_retval;
+        PACKED_REDUCTION_METHOD_T forced_retval = critical_reduce_block;
 
         int atomic_available, tree_available;
 
         switch( ( forced_retval = __kmp_force_reduction_method ) )
         {
-            case critical_reduce_block:
+        case critical_reduce_block:
                 KMP_ASSERT( lck );              // lck should be != 0
                 break;
 
             case atomic_reduce_block:
                 atomic_available = FAST_REDUCTION_ATOMIC_METHOD_GENERATED;
-                KMP_ASSERT( atomic_available ); // atomic_available should be != 0
+                if( ! atomic_available ) {
+                    KMP_WARNING(RedMethodNotSupported, "atomic");
+                    forced_retval = critical_reduce_block;
+                }
                 break;
 
             case tree_reduce_block:
                 tree_available = FAST_REDUCTION_TREE_METHOD_GENERATED;
-                KMP_ASSERT( tree_available );   // tree_available should be != 0
-                #if KMP_FAST_REDUCTION_BARRIER
-                forced_retval = TREE_REDUCE_BLOCK_WITH_REDUCTION_BARRIER;
-                #endif
+                if( ! tree_available ) {
+                    KMP_WARNING(RedMethodNotSupported, "tree");
+                    forced_retval = critical_reduce_block;
+                } else {
+                    #if KMP_FAST_REDUCTION_BARRIER
+                    forced_retval = TREE_REDUCE_BLOCK_WITH_REDUCTION_BARRIER;
+                    #endif
+                }
                 break;
 
             default: