Merge array allocation and List._copyFromObjectArray to provide fast path for large arrays.

runtime/vm/intermediate_language.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/intermediate_language.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/bit_vector.h"
 #include "vm/cpu.h"
 #include "vm/dart_entry.h"
@@ skipping 1583 matching lines @@
   StaticCallInstr* call = instance()->definition()->AsStaticCall();
   if (call != NULL) {
     if (call->is_known_list_constructor() &&
         IsFixedLengthArrayCid(call->Type()->ToCid())) {
       return call->ArgumentAt(1);
     }
     if (call->is_native_list_factory()) {
       return call->ArgumentAt(0);
     }
   }
+
+  CreateArrayInstr* create_array = instance()->definition()->AsCreateArray();
+  if ((create_array != NULL) &&
+      (recognized_kind() == MethodRecognizer::kObjectArrayLength)) {
+    return create_array->num_elements()->definition();
+  }
+
   // For arrays with guarded lengths, replace the length load
   // with a constant.
   LoadFieldInstr* load_array = instance()->definition()->AsLoadField();
   if (load_array != NULL) {
     const Field* field = load_array->field();
     if ((field != NULL) && (field->guarded_list_length() >= 0)) {
       return flow_graph->GetConstant(
           Smi::Handle(Smi::New(field->guarded_list_length())));
     }
   }
@@ skipping 1474 matching lines @@
     case Token::kTRUNCDIV: return 0;
     case Token::kMOD: return 1;
     default: UNIMPLEMENTED(); return -1;
   }
 }
 
 
 #undef __
 
 }  // namespace dart