Fall back to megamorphic stub when dispatching calls to rare classes.

runtime/vm/object.h

 // Copyright (c) 2012, 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.
 
 #ifndef RUNTIME_VM_OBJECT_H_
 #define RUNTIME_VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 1888 matching lines @@
   void ResetSwitchable(Zone* zone) const;
 
 // Note: only deopts with reasons before Unknown in this list are recorded in
 // the ICData. All other reasons are used purely for informational messages
 // printed during deoptimization itself.
 #define DEOPT_REASONS(V)                                                       \
   V(BinarySmiOp)                                                               \
   V(BinaryMintOp)                                                              \
   V(DoubleToSmi)                                                               \
   V(CheckSmi)                                                                  \
+  V(CheckClass)                                                                \
   V(Unknown)                                                                   \
   V(PolymorphicInstanceCallTestFail)                                           \
   V(UnaryMintOp)                                                               \
   V(BinaryDoubleOp)                                                            \
   V(UnaryOp)                                                                   \
   V(UnboxInteger)                                                              \
-  V(CheckClass)                                                                \
   V(CheckArrayBound)                                                           \
   V(AtCall)                                                                    \
   V(GuardField)                                                                \
   V(TestCids)                                                                  \
   V(NumReasons)
 
   enum DeoptReasonId {
 #define DEFINE_ENUM_LIST(name) kDeopt##name,
     DEOPT_REASONS(DEFINE_ENUM_LIST)
 #undef DEFINE_ENUM_LIST
@@ skipping 7066 matching lines @@
 
 inline void TypeArguments::SetHash(intptr_t value) const {
   // This is only safe because we create a new Smi, which does not cause
   // heap allocation.
   StoreSmi(&raw_ptr()->hash_, Smi::New(value));
 }
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_OBJECT_H_