--- old/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core.common/src/org/graalvm/compiler/core/common/type/AbstractObjectStamp.java	2019-03-12 08:08:42.687229542 +0100
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core.common/src/org/graalvm/compiler/core/common/type/AbstractObjectStamp.java	2019-03-12 08:08:42.307227070 +0100
@@ -48,6 +48,13 @@
         this.exactType = exactType;
     }
 
+    @Override
+    public void accept(Visitor v) {
+        super.accept(v);
+        v.visitObject(type);
+        v.visitBoolean(exactType);
+    }
+
     protected abstract AbstractObjectStamp copyWith(ResolvedJavaType newType, boolean newExactType, boolean newNonNull, boolean newAlwaysNull);
 
     @Override