*** old/src/java.base/share/classes/java/lang/invoke/MethodHandle.java	Thu Jan 22 20:49:32 2015
--- new/src/java.base/share/classes/java/lang/invoke/MethodHandle.java	Thu Jan 22 20:49:32 2015

*** 432,441 ****
--- 432,443 ----
      private final MethodType type;
      /*private*/ final LambdaForm form;
      // form is not private so that invokers can easily fetch it
      /*private*/ MethodHandle asTypeCache;
      // asTypeCache is not private so that invokers can easily fetch it
+     /*non-public*/ byte customizationCount;
+     // customizationCount should be accessible from invokers
  
      /**
       * Reports the type of this method handle.
       * Every invocation of this method handle via {@code invokeExact} must exactly match this type.
       * @return the method handle type

*** 452,464 ****
--- 454,466 ----
      // @param type type (permanently assigned) of the new method handle
      /*non-public*/ MethodHandle(MethodType type, LambdaForm form) {
          type.getClass();  // explicit NPE
          form.getClass();  // explicit NPE
          this.type = type;
!         this.form = form.uncustomize();
  
!         this.form.prepare();  // TO DO:  Try to delay this step until just before invocation.
      }
  
      /**
       * Invokes the method handle, allowing any caller type descriptor, but requiring an exact type match.
       * The symbolic type descriptor at the call site of {@code invokeExact} must

*** 1423,1438 ****
--- 1425,1452 ----
       * but it is likely that the new one will be preferred for new executions.
       * Use with discretion.
       */
      /*non-public*/
      void updateForm(LambdaForm newForm) {
+         assert(newForm.customized == null || newForm.customized == this);
          if (form == newForm)  return;
          newForm.prepare();  // as in MethodHandle.<init>
          UNSAFE.putObject(this, FORM_OFFSET, newForm);
          UNSAFE.fullFence();
      }
  
+     /** Craft a LambdaForm customized for this particular MethodHandle */
+     /*non-public*/
+     void customize() {
+         if (form.customized == null) {
+             LambdaForm newForm = form.customize(this);
+             updateForm(newForm);
+         } else {
+             assert(form.customized == this);
+         }
+     }
+ 
      private static final long FORM_OFFSET;
      static {
          try {
              FORM_OFFSET = UNSAFE.objectFieldOffset(MethodHandle.class.getDeclaredField("form"));
          } catch (ReflectiveOperationException ex) {