Add a helper function for allocation of deoptimization history.

runtime/vm/compiler.cc

 // 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.
 
 #include "vm/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/code_generator.h"
@@ skipping 481 matching lines @@
 
       if (optimized) {
         CodePatcher::PatchEntry(Code::Handle(function.CurrentCode()));
         function.SetCode(code);
         if (FLAG_trace_compiler) {
           OS::Print("--> patching entry %#"Px"\n",
                     Code::Handle(function.unoptimized_code()).EntryPoint());
         }
 
         // If not yet present, allocate deoptimization history array.
-        Array& deopt_history = Array::Handle(function.deopt_history());
-        if (deopt_history.IsNull()) {
-          deopt_history = Array::New(FLAG_deoptimization_counter_threshold);
-          function.set_deopt_history(deopt_history);
-        }
+        function.EnsureDeoptHistory();
 
         for (intptr_t i = 0; i < guarded_fields.length(); i++) {
           const Field& field = *guarded_fields[i];
           field.RegisterDependentCode(code);
         }
       } else {
         function.set_unoptimized_code(code);
         function.SetCode(code);
         ASSERT(CodePatcher::CodeIsPatchable(code));
       }
@@ skipping 351 matching lines @@
       Object::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
     isolate->set_long_jump_base(base);
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart