Reuse empty StoreBufferBlocks.

runtime/vm/scavenger.cc

 // Copyright (c) 2011, 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/scavenger.h"
 
 #include <algorithm>
 #include <map>
 #include <utility>
 
@@ skipping 508 matching lines @@
   // Iterating through the store buffers.
   // Grab the deduplication sets out of the isolate's consolidated store buffer.
   StoreBufferBlock* pending = isolate->store_buffer()->Blocks();
   intptr_t total_count = 0;
   while (pending != NULL) {
     StoreBufferBlock* next = pending->next();
     // Generated code appends to store buffers; tell MemorySanitizer.
     MSAN_UNPOISON(pending, sizeof(*pending));
     intptr_t count = pending->Count();
     total_count += count;
-    for (intptr_t i = 0; i < count; i++) {
-      RawObject* raw_object = pending->At(i);
+    while (!pending->IsEmpty()) {
+      RawObject* raw_object = pending->Pop();
       ASSERT(raw_object->IsRemembered());
       raw_object->ClearRememberedBit();
       visitor->VisitingOldObject(raw_object);
       raw_object->VisitPointers(visitor);
     }
-    delete pending;
+    pending->Reset();
+    isolate->store_buffer()->PushBlock(pending);
     pending = next;
   }
   heap_->RecordData(kStoreBufferEntries, total_count);
   heap_->RecordData(kDataUnused1, 0);
   heap_->RecordData(kDataUnused2, 0);
   // Done iterating through old objects remembered in the store buffers.
   visitor->VisitingOldObject(NULL);
 }
 
 
@@ skipping 355 matching lines @@
 }
 
 
 void Scavenger::FreeExternal(intptr_t size) {
   ASSERT(size >= 0);
   external_size_ -= size;
   ASSERT(external_size_ >= 0);
 }
 
 }  // namespace dart