--- old/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.graph/src/org/graalvm/compiler/graph/Node.java	2017-09-12 22:24:29.818959853 -0700
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.graph/src/org/graalvm/compiler/graph/Node.java	2017-09-12 22:24:29.679953589 -0700
@@ -38,6 +38,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
 
 import org.graalvm.compiler.core.common.Fields;
 import org.graalvm.compiler.core.common.type.AbstractPointerStamp;
@@ -598,6 +599,15 @@
         }
     }
 
+    /**
+     * Update the source position only if it is null.
+     */
+    public void updateNodeSourcePosition(Supplier<NodeSourcePosition> sourcePositionSupp) {
+        if (this.sourcePosition == null) {
+            setNodeSourcePosition(sourcePositionSupp.get());
+        }
+    }
+
     public DebugCloseable withNodeSourcePosition() {
         return graph.withNodeSourcePosition(this);
     }