Only check the new portion of an expanded range.

runtime/vm/code_generator.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/code_generator.h"
 
 #include "vm/assembler.h"
 #include "vm/ast.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
@@ skipping 1088 matching lines @@
   if (target_function.IsNull()) {
     target_function = InlineCacheMissHelper(receiver, descriptor, name);
   }
   if (target_function.IsNull()) {
     ASSERT(!FLAG_lazy_dispatchers);
   } else {
     ic_data.AddReceiverCheck(receiver.GetClassId(), target_function);
   }
 
   if (old_target.raw() == target_function.raw()) {
-    intptr_t lower, upper;
+    intptr_t lower, upper, unchecked_lower, unchecked_upper;
     if (receiver.GetClassId() < cache.lower_limit()) {
       lower = receiver.GetClassId();
+      unchecked_lower = receiver.GetClassId();
       upper = cache.upper_limit();
+      unchecked_upper = cache.lower_limit() - 1;
     } else {
       lower = cache.lower_limit();
+      unchecked_lower = cache.upper_limit() + 1;
       upper = receiver.GetClassId();
+      unchecked_upper = receiver.GetClassId();
     }
 
-    if (IsSingleTarget(isolate, zone, lower, upper, target_function, name)) {
+    if (IsSingleTarget(isolate, zone, unchecked_lower, unchecked_upper,
+                       target_function, name)) {
       cache.set_lower_limit(lower);
       cache.set_upper_limit(upper);
       // Return the ICData. The single target stub will jump to continue in the
       // IC call stub.
       arguments.SetReturn(ic_data);
       return;
     }
   }
 
   // Call site is not single target, switch to call using ICData.
@@ skipping 1087 matching lines @@
   const intptr_t elm_size = old_data.ElementSizeInBytes();
   const TypedData& new_data =
       TypedData::Handle(TypedData::New(cid, new_size, Heap::kOld));
   TypedData::Copy(new_data, 0, old_data, 0, old_size * elm_size);
   typed_data_cell.SetAt(0, new_data);
   arguments.SetReturn(new_data);
 }
 
 
 }  // namespace dart