Drain StoreBufferBlock into store buffer instead of iterating over it directly.

runtime/vm/store_buffer.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/store_buffer.h"
 
 #include "platform/assert.h"
 #include "vm/runtime_entry.h"
 
 namespace dart {
 
 DEFINE_LEAF_RUNTIME_ENTRY(void, StoreBufferBlockProcess, Isolate* isolate) {
   isolate->store_buffer_block()->ProcessBuffer(isolate);
 }
 END_LEAF_RUNTIME_ENTRY
 
 
 void StoreBufferBlock::ProcessBuffer() {
   ProcessBuffer(Isolate::Current());
 }
 
 
 void StoreBufferBlock::ProcessBuffer(Isolate* isolate) {
-  StoreBuffer* buffer = isolate->store_buffer();
-  int32_t end = top_;
-  for (int32_t i = 0; i < end; i++) {
-    buffer->AddPointer(pointers_[i]);
-  }
-  top_ = 0;  // Reset back to the beginning.
+  isolate->store_buffer()->ProcessBlock(this);
 }
 
 
 bool StoreBufferBlock::Contains(uword pointer) {
   for (int32_t i = 0; i < top_; i++) {
     if (pointers_[i] == pointer) {
       return true;
     }
   }
   return false;
@@ skipping 14 matching lines @@
 void StoreBuffer::Reset() {
   DedupSet* current = DedupSets();
   while (current != NULL) {
     DedupSet* next = current->next();
     delete current;
     current = next;
   }
 }
 
 
+bool StoreBuffer::AddPointerInternal(uword address) {
+  ASSERT(dedup_sets_ != NULL);
+  ASSERT(Isolate::Current()->heap()->OldContains(address));
+  ASSERT((address & kSmiTagMask) != kSmiTag);
+  if (!dedup_sets_->set()->Add(address)) {
+    // Add a new DedupSet.
+    dedup_sets_ = new DedupSet(dedup_sets_);
+    count_++;
+    return true;
+  }
+  return false;
+}
+
+
 void StoreBuffer::AddPointer(uword address) {
-  ASSERT(dedup_sets_ != NULL);
-  ASSERT(Isolate::Current()->heap()->OldContains(address));
-  ASSERT((address & kSmiTagMask) != kSmiTag);
-  if (!dedup_sets_->set()->Add(address)) {
-    // Add a new DedupSet. Schedule an interrupt if we have run over the max
-    // number of DedupSets.
-    dedup_sets_ = new DedupSet(dedup_sets_);
-    count_++;
-    // TODO(iposva): Fix magic number.
-    if (count_ > 100) {
-      Isolate::Current()->ScheduleInterrupts(Isolate::kStoreBufferInterrupt);
-    }
+  if (AddPointerInternal(address)) {
+    // Had to create a new DedupSet.
+    CheckThreshold();
   }
 }
 
+
+bool StoreBuffer::DrainBlock(StoreBufferBlock* block) {
+  const intptr_t old_count = count_;
+  intptr_t entries = block->Count();
+  for (intptr_t i = 0; i < entries; i++) {
+    AddPointerInternal(block->At(i));
+  }
+  block->Reset();
+  return (count_ > old_count);
+}
+
+
+void StoreBuffer::CheckThreshold() {
+  // Schedule an interrupt if we have run over the max number of DedupSets.
+  // TODO(iposva): Fix magic number.
+  if (count_ > 100) {
+    Isolate::Current()->ScheduleInterrupts(Isolate::kStoreBufferInterrupt);
+  }
+}
+
+
+void StoreBuffer::ProcessBlock(StoreBufferBlock* block) {
+  if (DrainBlock(block)) {
+    CheckThreshold();
+  }
+}
+
 }  // namespace dart