--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/stubs/SnippetStub.java	Fri Sep 14 13:18:52 2018 +0800
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot/src/org/graalvm/compiler/hotspot/stubs/SnippetStub.java	Thu Sep 13 22:45:12 2018 -0700
@@ -107,9 +107,15 @@
         plugins.prependParameterPlugin(new ConstantBindingParameterPlugin(makeConstArgs(), metaAccess, snippetReflection));
         GraphBuilderConfiguration config = GraphBuilderConfiguration.getSnippetDefault(plugins);
 
+        // @formatter:off
         // Stubs cannot have optimistic assumptions since they have
         // to be valid for the entire run of the VM.
-        final StructuredGraph graph = new StructuredGraph.Builder(options, debug).method(method).compilationId(compilationId).build();
+        final StructuredGraph graph = new StructuredGraph.Builder(options, debug).
+                        method(method).
+                        compilationId(compilationId).
+                        setIsSubstitution(true).
+                        build();
+        // @formatter:on
         try (DebugContext.Scope outer = debug.scope("SnippetStub", graph)) {
             graph.disableUnsafeAccessTracking();