Basic array capacity feedback via allocation sites.

src/builtins.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/base/once.h"
 #include "src/bootstrapper.h"
@@ skipping 330 matching lines @@
       int capacity = new_length + (new_length >> 1) + 16;
       Handle<FixedArray> new_elms =
           isolate->factory()->NewUninitializedFixedArray(capacity);
 
       ElementsAccessor* accessor = array->GetElementsAccessor();
       accessor->CopyElements(
           elms_obj, 0, kind, new_elms, 0,
           ElementsAccessor::kCopyToEndAndInitializeToHole);
 
       elms = new_elms;
+
+      // Do we have an AllocationMemento, to store this feedback?
+      AllocationMemento* memento =
+          isolate->heap()->FindAllocationMemento(*array);
+      if (memento != NULL && memento->IsValid()) {
+        AllocationSite* site = memento->GetAllocationSite();
+        site->DigestInitialElementsCapacityFeedback(new_length);
+      }
     }
 
     // Add the provided values.
     DisallowHeapAllocation no_gc;
     WriteBarrierMode mode = elms->GetWriteBarrierMode(no_gc);
     for (int index = 0; index < to_add; index++) {
       elms->set(index + len, args[index + 1], mode);
     }
 
     if (*elms != array->elements()) {
@@ skipping 1284 matching lines @@
 }
 BUILTIN_LIST_C(DEFINE_BUILTIN_ACCESSOR_C)
 BUILTIN_LIST_A(DEFINE_BUILTIN_ACCESSOR_A)
 BUILTIN_LIST_H(DEFINE_BUILTIN_ACCESSOR_H)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 
 
 } }  // namespace v8::internal