Use heap iterator in store buffer when page was swept precisely.

src/store-buffer.cc

 // Copyright 2011 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/store-buffer.h"
 
 #include <algorithm>
 
 #include "src/v8.h"
 
@@ skipping 497 matching lines @@
             if (page->parallel_sweeping() > MemoryChunk::SWEEPING_FINALIZE) {
               heap_->mark_compact_collector()->SweepInParallel(page, owner);
               if (page->parallel_sweeping() > MemoryChunk::SWEEPING_FINALIZE) {
                 // We were not able to sweep that page, i.e., a concurrent
                 // sweeper thread currently owns this page.
                 // TODO(hpayer): This may introduce a huge pause here. We
                 // just care about finish sweeping of the scan on scavenge page.
                 heap_->mark_compact_collector()->EnsureSweepingCompleted();
               }
             }
-            FindPointersToNewSpaceInRegion(
-                start, end, slot_callback, clear_maps);
+            // TODO(hpayer): remove the special casing and merge map and pointer
+            // space handling as soon as we removed conservative sweeping.
+            CHECK(page->owner() == heap_->old_pointer_space());
+            if (heap_->old_pointer_space()->swept_precisely()) {
+              HeapObjectIterator iterator(page, NULL);
+              for (HeapObject* heap_object = iterator.Next();
+                   heap_object != NULL; heap_object = iterator.Next()) {
+                // We iterate over objects that contain pointers only.

[rmcilroy, 2014/07/24 10:24:48]

nit - new space pointers only.

[Hannes Payer (out of office), 2014/07/24 10:40:08]

Done.

+                if (heap_object->MayContainNewSpacePointers()) {
+                  FindPointersToNewSpaceInRegion(
+                      heap_object->address() + HeapObject::kHeaderSize,
+                      heap_object->address() + heap_object->Size(),
+                      slot_callback, clear_maps);
+                }
+              }
+            } else {
+              FindPointersToNewSpaceInRegion(start, end, slot_callback,
+                                             clear_maps);
+            }
           }
         }
       }
     }
     if (callback_ != NULL) {
       (*callback_)(heap_, NULL, kStoreBufferScanningPageEvent);
     }
   }
 }
 
@@ skipping 45 matching lines @@
     }
     old_buffer_is_sorted_ = false;
     old_buffer_is_filtered_ = false;
     *old_top_++ = reinterpret_cast<Address>(int_addr << kPointerSizeLog2);
     ASSERT(old_top_ <= old_limit_);
   }
   heap_->isolate()->counters()->store_buffer_compactions()->Increment();
 }
 
 } }  // namespace v8::internal