Simplify type argument instantiation cache lookup by introducing an array

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 VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 349 matching lines @@
   }
   static const TypeArguments& null_type_arguments() {
     ASSERT(null_type_arguments_ != NULL);
     return *null_type_arguments_;
   }
 
   static const Array& empty_array() {
     ASSERT(empty_array_ != NULL);
     return *empty_array_;
   }
+  static const Array& zero_array() {
+    ASSERT(zero_array_ != NULL);
+    return *zero_array_;
+  }
 
   static const PcDescriptors& empty_descriptors() {
     ASSERT(empty_descriptors_ != NULL);
     return *empty_descriptors_;
   }
 
   // The sentinel is a value that cannot be produced by Dart code.
   // It can be used to mark special values, for example to distinguish
   // "uninitialized" fields.
   static const Instance& sentinel() {
@@ skipping 227 matching lines @@
   static RawClass* unwind_error_class_;  // Class of UnwindError.
 
   // The static values below are read-only handle pointers for singleton
   // objects that are shared between the different isolates.
   static Object* null_object_;
   static Array* null_array_;
   static String* null_string_;
   static Instance* null_instance_;
   static TypeArguments* null_type_arguments_;
   static Array* empty_array_;
+  static Array* zero_array_;
   static PcDescriptors* empty_descriptors_;
   static Instance* sentinel_;
   static Instance* transition_sentinel_;
   static Instance* unknown_constant_;
   static Instance* non_constant_;
   static Bool* bool_true_;
   static Bool* bool_false_;
   static Smi* smi_illegal_cid_;
   static LanguageError* snapshot_writer_error_;
   static LanguageError* branch_offset_error_;
@@ skipping 5989 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_