Implemented lazy sweeping of new space.

src/store-buffer.h

Index: src/store-buffer.h
diff --git a/src/store-buffer.h b/src/store-buffer.h
index 520cbc01626b698607928dbd83638ba220096fb2..ca92a6a7b31e15731e7f2102e47c095b394f0336 100644
--- a/src/store-buffer.h
+++ b/src/store-buffer.h
@@ -43,8 +43,10 @@ class StoreBuffer;
 
 typedef void (*ObjectSlotCallback)(HeapObject** from, HeapObject* to);
 
-typedef void (StoreBuffer::*RegionCallback)(
-    Address start, Address end, ObjectSlotCallback slot_callback);
+typedef void (StoreBuffer::*RegionCallback)(Address start,
+                                            Address end,
+                                            ObjectSlotCallback slot_callback,
+                                            bool clear_maps);
 
 // Used to implement the write barrier by collecting addresses of pointers
 // between spaces.
@@ -81,7 +83,7 @@ class StoreBuffer {
   // Iterates over all pointers that go from old space to new space.  It will
   // delete the store buffer as it starts so the callback should reenter
   // surviving old-to-new pointers into the store buffer to rebuild it.
-  void IteratePointersToNewSpace(ObjectSlotCallback callback);
+  void IteratePointersToNewSpace(ObjectSlotCallback callback, bool clear_maps);

[titzer, 2013/07/10 17:06:35]

Boolean flags of doom be gone! Recommend to have two separate methods, one which
clears and one which does not clear. The private implementation can use internal
booleans to avoid duplicating the guts, but the public interface should be more
well-defined.

Either that, or you could have the callback itself doing the clearing...

[Hannes Payer (out of office), 2013/07/11 07:30:40]

Done.

 
   static const int kStoreBufferOverflowBit = 1 << (14 + kPointerSizeLog2);
   static const int kStoreBufferSize = kStoreBufferOverflowBit;
@@ -166,7 +168,8 @@ class StoreBuffer {
 
   void FindPointersToNewSpaceInRegion(Address start,
                                       Address end,
-                                      ObjectSlotCallback slot_callback);
+                                      ObjectSlotCallback slot_callback,
+                                      bool clear_maps);
 
   // For each region of pointers on a page in use from an old space call
   // visit_pointer_region callback.
@@ -182,20 +185,24 @@ class StoreBuffer {
   void FindPointersToNewSpaceInMaps(
     Address start,
     Address end,
-    ObjectSlotCallback slot_callback);
+    ObjectSlotCallback slot_callback,
+    bool clear_maps);
 
   void FindPointersToNewSpaceInMapsRegion(
     Address start,
     Address end,
-    ObjectSlotCallback slot_callback);
+    ObjectSlotCallback slot_callback,
+    bool clear_maps);
 
   void FindPointersToNewSpaceOnPage(
     PagedSpace* space,
     Page* page,
     RegionCallback region_callback,
-    ObjectSlotCallback slot_callback);
+    ObjectSlotCallback slot_callback,
+    bool clear_maps);
 
-  void IteratePointersInStoreBuffer(ObjectSlotCallback slot_callback);
+  void IteratePointersInStoreBuffer(ObjectSlotCallback slot_callback,
+                                    bool clear_maps);
 
 #ifdef VERIFY_HEAP
   void VerifyPointers(PagedSpace* space, RegionCallback region_callback);