--- a/graal/com.oracle.graal.api.replacements/src/com/oracle/graal/api/replacements/MethodSubstitution.java	Mon Apr 08 19:37:23 2013 +0200
+++ b/graal/com.oracle.graal.api.replacements/src/com/oracle/graal/api/replacements/MethodSubstitution.java	Mon Apr 08 20:15:44 2013 +0200
@@ -60,4 +60,11 @@
      * not important.
      */
     boolean isForcedInlining() default false;
+
+    /**
+     * Determines if the substitution is for a method that may not be part of the runtime. For
+     * example, a method introduced in a later JDK version. Substitutions for such methods are
+     * omitted if the original method cannot be found.
+     */
+    boolean optional() default false;
 }

--- a/graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/spi/MacroSubstitution.java	Mon Apr 08 19:37:23 2013 +0200
+++ b/graal/com.oracle.graal.nodes/src/com/oracle/graal/nodes/spi/MacroSubstitution.java	Mon Apr 08 20:15:44 2013 +0200
@@ -61,6 +61,13 @@
     String signature() default "";
 
     /**
+     * Determines if the substitution is for a method that may not be part of the runtime. For
+     * example, a method introduced in a later JDK version. Substitutions for such methods are
+     * omitted if the original method cannot be found.
+     */
+    boolean optional() default false;
+
+    /**
      * The node class with which the method invocation should be replaced. It needs to be a subclass
      * of {@link FixedWithNextNode}, and it is expected to provide a public constructor that takes
      * an {@link InvokeNode} as a parameter.

--- a/graal/com.oracle.graal.replacements/src/com/oracle/graal/replacements/ReplacementsImpl.java	Mon Apr 08 19:37:23 2013 +0200
+++ b/graal/com.oracle.graal.replacements/src/com/oracle/graal/replacements/ReplacementsImpl.java	Mon Apr 08 20:15:44 2013 +0200
@@ -146,7 +146,7 @@
                 }
                 String originalName = originalName(substituteMethod, methodSubstitution.value());
                 Class[] originalParameters = originalParameters(substituteMethod, methodSubstitution.signature(), methodSubstitution.isStatic());
-                Member originalMethod = originalMethod(classSubstitution, originalName, originalParameters);
+                Member originalMethod = originalMethod(classSubstitution, methodSubstitution.optional(), originalName, originalParameters);
                 if (originalMethod != null) {
                     ResolvedJavaMethod original = registerMethodSubstitution(originalMethod, substituteMethod);
                     if (original != null && methodSubstitution.isForcedInlining()) {
@@ -157,7 +157,7 @@
             if (macroSubstitution != null) {
                 String originalName = originalName(substituteMethod, macroSubstitution.value());
                 Class[] originalParameters = originalParameters(substituteMethod, macroSubstitution.signature(), macroSubstitution.isStatic());
-                Member originalMethod = originalMethod(classSubstitution, originalName, originalParameters);
+                Member originalMethod = originalMethod(classSubstitution, macroSubstitution.optional(), originalName, originalParameters);
                 if (originalMethod != null) {
                     ResolvedJavaMethod original = registerMacroSubstitution(originalMethod, macroSubstitution.macro());
                     if (original != null && macroSubstitution.isForcedInlining()) {
@@ -462,7 +462,7 @@
         return parameters;
     }
 
-    private static Member originalMethod(ClassSubstitution classSubstitution, String name, Class[] parameters) {
+    private static Member originalMethod(ClassSubstitution classSubstitution, boolean optional, String name, Class[] parameters) {
         Class<?> originalClass = classSubstitution.value();
         if (originalClass == ClassSubstitution.class) {
             originalClass = resolveType(classSubstitution.className(), classSubstitution.optional());
@@ -478,6 +478,9 @@
                 return originalClass.getDeclaredMethod(name, parameters);
             }
         } catch (NoSuchMethodException | SecurityException e) {
+            if (optional) {
+                return null;
+            }
             throw new GraalInternalError(e);
         }
     }