Optimize function at its entry instead of at exit.

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 2231 matching lines @@
     kTryIndexEntry = 4,     // Try block index.
     // We would potentially be adding other objects here like
     // pointer maps for optimized functions, local variables information  etc.
     kNumberOfEntries = 5,
   };
 
  public:
   enum Kind {
     kDeoptBefore = 0,  // Deoptimization continuation point before instruction.
     kDeoptAfter,       // Deoptimization continuation point after instruction.
+    kEntryPatch,       // Location where to patch entry.
     kPatchCode,        // Buffer for patching code entry.
     kLazyDeoptJump,    // Lazy deoptimization trampoline.
     kIcCall,           // IC call.
     kFuncCall,         // Call to known target, e.g. static call, closure call.
     kReturn,           // Return from function.
     kOther
   };
 
   intptr_t Length() const;
 
@@ skipping 3981 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_