Simple non-incremental compaction by evacuation.

src/store-buffer.cc

Index: src/store-buffer.cc
diff --git a/src/store-buffer.cc b/src/store-buffer.cc
index 027c2f39eaaa954f700e9a715f512478275efe8f..18e972185d81c72ec48bf5821356e77683796471 100644
--- a/src/store-buffer.cc
+++ b/src/store-buffer.cc
@@ -555,13 +555,9 @@ void StoreBuffer::FindPointersToNewSpaceOnPage(
 }
 
 
-
-void StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback) {
-  // We do not sort or remove duplicated entries from the store buffer because
-  // we expect that callback will rebuild the store buffer thus removing
-  // all duplicates and pointers to old space.
-  bool some_pages_to_scan = PrepareForIteration();
-
+template<StoreBuffer::IterationMode mode>
+void StoreBuffer::IteratePointersInStoreBuffer(
+    ObjectSlotCallback slot_callback) {
   Address* limit = old_top_;
   old_top_ = old_start_;
   {
@@ -571,6 +567,11 @@ void StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback) {
       Address* saved_top = old_top_;
 #endif
       Object** slot = reinterpret_cast<Object**>(*current);
+
+      // TODO(gc): we want to skip slots on evacuation candidates
+      // but we can't simply figure that out from slot address
+      // because slot can belong to a large object.

[Erik Corry, 2011/06/20 20:41:26]

Pity.  I was looking forward to seeing how you would do that :-)

+
       Object* object = *slot;
       if (heap_->InFromSpace(object)) {
         HeapObject* heap_object = reinterpret_cast<HeapObject*>(object);
@@ -582,6 +583,26 @@ void StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback) {
       ASSERT(old_top_ == saved_top + 1 || old_top_ == saved_top);
     }
   }
+

[Erik Corry, 2011/06/20 20:41:26]

Spurious blank line.

[Vyacheslav Egorov (Chromium), 2011/06/21 11:44:48]

Done.

+}
+
+
+void StoreBuffer::IteratePointersToNewSpace(ObjectSlotCallback slot_callback,
+                                            IterationMode mode) {
+  // We do not sort or remove duplicated entries from the store buffer because
+  // we expect that callback will rebuild the store buffer thus removing
+  // all duplicates and pointers to old space.
+  bool some_pages_to_scan = PrepareForIteration();
+
+  if (mode == SKIP_SLOTS_IN_EVACUATION_CANDIDATES) {
+    IteratePointersInStoreBuffer<SKIP_SLOTS_IN_EVACUATION_CANDIDATES>(
+        slot_callback);
+  } else {
+    ASSERT(mode == VISIT_ALL_SLOTS);
+    IteratePointersInStoreBuffer<VISIT_ALL_SLOTS>(slot_callback);
+  }
+
+
   // We are done scanning all the pointers that were in the store buffer, but
   // there may be some pages marked scan_on_scavenge that have pointers to new
   // space that are not in the store buffer.  We must scan them now.  As we