--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core.common/src/org/graalvm/compiler/core/common/type/AbstractPointerStamp.java	Thu Nov 15 21:05:47 2018 +0100
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core.common/src/org/graalvm/compiler/core/common/type/AbstractPointerStamp.java	Thu Nov 15 09:04:07 2018 -0800
@@ -142,10 +142,13 @@
     @Override
     public Constant asConstant() {
         if (alwaysNull) {
-            return JavaConstant.NULL_POINTER;
-        } else {
-            return null;
+            return nullConstant();
         }
+        return super.asConstant();
+    }
+
+    public JavaConstant nullConstant() {
+        return JavaConstant.NULL_POINTER;
     }
 
     @Override