*** old/src/share/vm/opto/library_call.cpp	Tue Oct 21 16:47:08 2014
--- new/src/share/vm/opto/library_call.cpp	Tue Oct 21 16:47:08 2014

*** 266,275 ****
--- 266,276 ----
    bool inline_unsafe_ordered_store(BasicType type);
    bool inline_unsafe_fence(vmIntrinsics::ID id);
    bool inline_fp_conversions(vmIntrinsics::ID id);
    bool inline_number_methods(vmIntrinsics::ID id);
    bool inline_reference_get();
+   bool inline_Class_cast();
    bool inline_aescrypt_Block(vmIntrinsics::ID id);
    bool inline_cipherBlockChaining_AESCrypt(vmIntrinsics::ID id);
    Node* inline_cipherBlockChaining_AESCrypt_predicate(bool decrypting);
    Node* get_key_start_from_aescrypt_object(Node* aescrypt_object);
    Node* get_original_key_start_from_aescrypt_object(Node* aescrypt_object);

*** 867,876 ****
--- 868,879 ----
  
    case vmIntrinsics::_getCallerClass:           return inline_native_Reflection_getCallerClass();
  
    case vmIntrinsics::_Reference_get:            return inline_reference_get();
  
+   case vmIntrinsics::_class_cast:               return inline_Class_cast();
+ 
    case vmIntrinsics::_aescrypt_encryptBlock:
    case vmIntrinsics::_aescrypt_decryptBlock:    return inline_aescrypt_Block(intrinsic_id());
  
    case vmIntrinsics::_cipherBlockChaining_encryptAESCrypt:
    case vmIntrinsics::_cipherBlockChaining_decryptAESCrypt:

*** 3544,3553 ****
--- 3547,3599 ----
    C->set_has_split_ifs(true); // Has chance for split-if optimization
    set_result(region, phi);
    return true;
  }
  
+ //-------------------------inline_Class_cast-------------------
+ bool LibraryCallKit::inline_Class_cast() {
+   // See if we can statically collapse isInstance() check in Class.cast();
+   Node* mirror = argument(0); // Class
+   Node* obj    = argument(1);
+ 
+   const TypeInstPtr* mirror_con = _gvn.type(mirror)->isa_instptr();
+   if (mirror_con == NULL) {
+     return false;  // cannot happen?
+   }
+   const TypeOopPtr* obj_type = _gvn.type(obj)->isa_oopptr();
+   if (obj_type == NULL) {
+     return false;  // skip NULL_PTR and TOP
+   }
+ 
+   assert(mirror_con->klass()->as_instance_klass() == C->env()->Class_klass(), "sanity");
+   // We are loading a special hidden field from a Class mirror object,
+   // the field which points to the VM's Klass metaobject.
+ 
+   // java_mirror_type returns non-null for compile-time Class constants.
+   ciType* t = mirror_con->java_mirror_type();
+   if (t == NULL || !t->is_klass()) {
+     return false; // non-constant or primitive Class
+   }
+   // constant oop => constant klass
+   const TypeKlassPtr* superklass = TypeKlassPtr::make(t->as_klass());
+ 
+   if (superklass->singleton()) {
+     ciKlass* superk = superklass->klass();
+     ciKlass* subk = obj_type->klass();
+     if (subk != NULL && subk->is_loaded()) {
+       int static_res = C->static_subtype_check(superk, subk);
+       if (static_res == Compile::SSC_always_true) {
+         // isInstance() is true
+         set_result(obj);
+         return true;
+       }
+     }
+   }
+ 
+   return false;
+ }
+ 
  //--------------------------inline_native_subtype_check------------------------
  // This intrinsic takes the JNI calls out of the heart of
  // UnsafeFieldAccessorImpl.set, which improves Field.set, readObject, etc.
  bool LibraryCallKit::inline_native_subtype_check() {
    // Pull both arguments off the stack.