--- a/hotspot/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.code/src/org/graalvm/compiler/code/CompilationResult.java	Mon Dec 12 16:16:27 2016 +0300
+++ b/hotspot/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.code/src/org/graalvm/compiler/code/CompilationResult.java	Wed Mar 22 13:42:45 2017 -0700
@@ -34,6 +34,7 @@
 import java.util.Objects;
 
 import org.graalvm.compiler.graph.NodeSourcePosition;
+import org.graalvm.util.EconomicSet;
 
 import jdk.vm.ci.code.DebugInfo;
 import jdk.vm.ci.code.StackSlot;
@@ -363,9 +364,10 @@
      *
      * @param accessedFields the collected set of fields accessed during compilation
      */
-    public void setFields(Collection<ResolvedJavaField> accessedFields) {
-        assert accessedFields != null;
-        fields = accessedFields.toArray(new ResolvedJavaField[accessedFields.size()]);
+    public void setFields(EconomicSet<ResolvedJavaField> accessedFields) {
+        if (accessedFields != null) {
+            fields = accessedFields.toArray(new ResolvedJavaField[accessedFields.size()]);
+        }
     }
 
     /**