Reverting r4703.

src/heap.h

Index: src/heap.h
===================================================================
--- src/heap.h	(revision 4703)
+++ src/heap.h	(working copy)
@@ -206,11 +206,7 @@
 
 typedef String* (*ExternalStringTableUpdaterCallback)(Object** pointer);
 
-typedef bool (*DirtyRegionCallback)(Address start,
-                                    Address end,
-                                    ObjectSlotCallback copy_object_func);
 
-
 // The all static Heap captures the interface to the global object heap.
 // All JavaScript contexts by this process share the same object heap.
 
@@ -744,55 +740,18 @@
   // Iterates over all the other roots in the heap.
   static void IterateWeakRoots(ObjectVisitor* v, VisitMode mode);
 
-  enum ExpectedPageWatermarkState {
-    WATERMARK_SHOULD_BE_VALID,
-    WATERMARK_CAN_BE_INVALID
-  };
+  // Iterates remembered set of an old space.
+  static void IterateRSet(PagedSpace* space, ObjectSlotCallback callback);
 
-  // For each dirty region on a page in use from an old space call
-  // visit_dirty_region callback.
-  // If either visit_dirty_region or callback can cause an allocation
-  // in old space and changes in allocation watermark then
-  // can_preallocate_during_iteration should be set to true.
-  // All pages will be marked as having invalid watermark upon
-  // iteration completion.
-  static void IterateDirtyRegions(
-      PagedSpace* space,
-      DirtyRegionCallback visit_dirty_region,
-      ObjectSlotCallback callback,
-      ExpectedPageWatermarkState expected_page_watermark_state);
+  // Iterates a range of remembered set addresses starting with rset_start
+  // corresponding to the range of allocated pointers
+  // [object_start, object_end).
+  // Returns the number of bits that were set.
+  static int IterateRSetRange(Address object_start,
+                              Address object_end,
+                              Address rset_start,
+                              ObjectSlotCallback copy_object_func);
 
-  // Interpret marks as a bitvector of dirty marks for regions of size
-  // Page::kRegionSize aligned by Page::kRegionAlignmentMask and covering
-  // memory interval from start to top. For each dirty region call a
-  // visit_dirty_region callback. Return updated bitvector of dirty marks.
-  static uint32_t IterateDirtyRegions(uint32_t marks,
-                                      Address start,
-                                      Address end,
-                                      DirtyRegionCallback visit_dirty_region,
-                                      ObjectSlotCallback callback);
-
-  // Iterate pointers to new space found in memory interval from start to end.
-  // Update dirty marks for page containing start address.
-  static void IterateAndMarkPointersToNewSpace(Address start,
-                                               Address end,
-                                               ObjectSlotCallback callback);
-
-  // Iterate pointers to new space found in memory interval from start to end.
-  // Return true if pointers to new space was found.
-  static bool IteratePointersInDirtyRegion(Address start,
-                                           Address end,
-                                           ObjectSlotCallback callback);
-
-
-  // Iterate pointers to new space found in memory interval from start to end.
-  // This interval is considered to belong to the map space.
-  // Return true if pointers to new space was found.
-  static bool IteratePointersInDirtyMapsRegion(Address start,
-                                               Address end,
-                                               ObjectSlotCallback callback);
-
-
   // Returns whether the object resides in new space.
   static inline bool InNewSpace(Object* object);
   static inline bool InFromSpace(Object* object);
@@ -893,6 +852,17 @@
   static void ScavengePointer(HeapObject** p);
   static inline void ScavengeObject(HeapObject** p, HeapObject* object);
 
+  // Clear a range of remembered set addresses corresponding to the object
+  // area address 'start' with size 'size_in_bytes', eg, when adding blocks
+  // to the free list.
+  static void ClearRSetRange(Address start, int size_in_bytes);
+
+  // Rebuild remembered set in old and map spaces.
+  static void RebuildRSets();
+
+  // Update an old object's remembered set
+  static int UpdateRSet(HeapObject* obj);
+
   // Commits from space if it is uncommitted.
   static void EnsureFromSpaceIsCommitted();
 
@@ -985,20 +955,12 @@
 
   // Copy block of memory from src to dst. Size of block should be aligned
   // by pointer size.
-  static inline void CopyBlock(Address dst, Address src, int byte_size);
+  static inline void CopyBlock(Object** dst, Object** src, int byte_size);
 
-  static inline void CopyBlockToOldSpaceAndUpdateRegionMarks(Address dst,
-                                                             Address src,
-                                                             int byte_size);
-
   // Optimized version of memmove for blocks with pointer size aligned sizes and
   // pointer size aligned addresses.
-  static inline void MoveBlock(Address dst, Address src, int byte_size);
+  static inline void MoveBlock(Object** dst, Object** src, int byte_size);
 
-  static inline void MoveBlockToOldSpaceAndUpdateRegionMarks(Address dst,
-                                                             Address src,
-                                                             int byte_size);
-
   // Check new space expansion criteria and expand semispaces if it was hit.
   static void CheckNewSpaceExpansionCriteria();
 
@@ -1245,6 +1207,12 @@
   static void ReportStatisticsAfterGC();
 #endif
 
+  // Rebuild remembered set in an old space.
+  static void RebuildRSets(PagedSpace* space);
+
+  // Rebuild remembered set in the large object space.
+  static void RebuildRSets(LargeObjectSpace* space);
+
   // Slow part of scavenge object.
   static void ScavengeObjectSlow(HeapObject** p, HeapObject* object);
 
@@ -1333,11 +1301,11 @@
 
 
 #ifdef DEBUG
-// Visitor class to verify interior pointers in spaces that do not contain
-// or care about intergenerational references. All heap object pointers have to
-// point into the heap to a location that has a map pointer at its first word.
-// Caveat: Heap::Contains is an approximation because it can return true for
-// objects in a heap space but above the allocation pointer.
+// Visitor class to verify interior pointers that do not have remembered set
+// bits.  All heap object pointers have to point into the heap to a location
+// that has a map pointer at its first word.  Caveat: Heap::Contains is an
+// approximation because it can return true for objects in a heap space but
+// above the allocation pointer.
 class VerifyPointersVisitor: public ObjectVisitor {
  public:
   void VisitPointers(Object** start, Object** end) {
@@ -1352,11 +1320,10 @@
 };
 
 
-// Visitor class to verify interior pointers in spaces that use region marks
-// to keep track of intergenerational references.
-// As VerifyPointersVisitor but also checks that dirty marks are set
-// for regions covering intergenerational references.
-class VerifyPointersAndDirtyRegionsVisitor: public ObjectVisitor {
+// Visitor class to verify interior pointers that have remembered set bits.
+// As VerifyPointersVisitor but also checks that remembered set bits are
+// always set for pointers into new space.
+class VerifyPointersAndRSetVisitor: public ObjectVisitor {
  public:
   void VisitPointers(Object** start, Object** end) {
     for (Object** current = start; current < end; current++) {
@@ -1365,9 +1332,7 @@
         ASSERT(Heap::Contains(object));
         ASSERT(object->map()->IsMap());
         if (Heap::InNewSpace(object)) {
-          ASSERT(Heap::InToSpace(object));
-          Address addr = reinterpret_cast<Address>(current);
-          ASSERT(Page::FromAddress(addr)->IsRegionDirty(addr));
+          ASSERT(Page::IsRSetSet(reinterpret_cast<Address>(current), 0));
         }
       }
     }