Virtually dispatched scavengers

Use virtually dispatched specialized scavengers instead of single generic ScavengeObjectSlow implementation.

Rollback of r5041 with assertion checking callback alignment removed. Map space is iterated in a special fashion during scavenges so special callback alignment is not required.

Review URL: http://codereview.chromium.org/2950003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5047 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/bootstrapper.cc

@@ -812,6 +812,9 @@ void Genesis::InitializeGlobal(Handle<GlobalObject> inner_global,
     initial_map->set_instance_size(
         initial_map->instance_size() + 5 * kPointerSize);
     initial_map->set_instance_descriptors(*descriptors);
+    initial_map->set_scavenger(
+        Heap::GetScavenger(initial_map->instance_type(),
+                           initial_map->instance_size()));
   }
 
   {  // -- J S O N

src/factory.cc

@@ -277,6 +277,8 @@ Handle<Map> Factory::CopyMap(Handle<Map> src,
   copy->set_inobject_properties(inobject_properties);
   copy->set_unused_property_fields(inobject_properties);
   copy->set_instance_size(copy->instance_size() + instance_size_delta);
+  copy->set_scavenger(Heap::GetScavenger(copy->instance_type(),
+                                         copy->instance_size()));
   return copy;
 }
 

src/heap.h

@@ -774,11 +774,12 @@ class Heap : public AllStatic {
                                       DirtyRegionCallback visit_dirty_region,
                                       ObjectSlotCallback callback);
 
-  // Iterate pointers to new space found in memory interval from start to end.
+  // Iterate pointers to from semispace of 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);
+  static void IterateAndMarkPointersToFromSpace(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.
@@ -985,6 +986,8 @@ class Heap : public AllStatic {
 
   static void RecordStats(HeapStats* stats);
 
+  static Scavenger GetScavenger(int instance_type, int instance_size);
+
   // 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);
@@ -1232,17 +1235,7 @@ class Heap : public AllStatic {
     set_instanceof_cache_function(the_hole_value());
   }
 
-  // Helper function used by CopyObject to copy a source object to an
-  // allocated target object and update the forwarding pointer in the source
-  // object.  Returns the target object.
-  static inline HeapObject* MigrateObject(HeapObject* source,
-                                          HeapObject* target,
-                                          int size);
-
 #if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
-  // Record the copy of an object in the NewSpace's statistics.
-  static void RecordCopiedObject(HeapObject* obj);
-
   // Record statistics before and after garbage collection.
   static void ReportStatisticsBeforeGC();
   static void ReportStatisticsAfterGC();

src/mark-compact.cc

@@ -425,8 +425,10 @@ void MarkCompactCollector::MarkMapContents(Map* map) {
   // Since the descriptor array has been marked already, it is fine
   // that one of these fields contains a pointer to it.
   MarkingVisitor visitor;  // Has no state or contents.
-  visitor.VisitPointers(HeapObject::RawField(map, Map::kPrototypeOffset),
-                        HeapObject::RawField(map, Map::kSize));
+  visitor.VisitPointers(HeapObject::RawField(map,
+                                             Map::kPointerFieldsBeginOffset),
+                        HeapObject::RawField(map,
+                                             Map::kPointerFieldsEndOffset));
 }
 
 

src/objects-inl.h

@@ -2060,6 +2060,21 @@ void ExternalFloatArray::set(int index, float value) {
   ptr[index] = value;
 }
 
+inline Scavenger Map::scavenger() {
+  Scavenger callback = reinterpret_cast<Scavenger>(
+      READ_INTPTR_FIELD(this, kScavengerCallbackOffset));
+
+  ASSERT(callback == Heap::GetScavenger(instance_type(),
+                                        instance_size()));
+
+  return callback;
+}
+
+inline void Map::set_scavenger(Scavenger callback) {
+  WRITE_INTPTR_FIELD(this,
+                     kScavengerCallbackOffset,
+                     reinterpret_cast<intptr_t>(callback));
+}
 
 int Map::instance_size() {
   return READ_BYTE_FIELD(this, kInstanceSizeOffset) << kPointerSizeLog2;

src/objects.cc

@@ -2190,6 +2190,8 @@ Object* JSObject::NormalizeProperties(PropertyNormalizationMode mode,
     int new_instance_size = map()->instance_size() - instance_size_delta;
     new_map->set_inobject_properties(0);
     new_map->set_instance_size(new_instance_size);
+    new_map->set_scavenger(Heap::GetScavenger(new_map->instance_type(),
+                                              new_map->instance_size()));
     Heap::CreateFillerObjectAt(this->address() + new_instance_size,
                                instance_size_delta);
   }
@@ -5033,7 +5035,7 @@ void Map::ClearNonLiveTransitions(Object* real_prototype) {
 
 void Map::MapIterateBody(ObjectVisitor* v) {
   // Assumes all Object* members are contiguously allocated!
-  IteratePointers(v, kPrototypeOffset, kCodeCacheOffset + kPointerSize);
+  IteratePointers(v, kPointerFieldsBeginOffset, kPointerFieldsEndOffset);
 }
 
 

src/objects.h

@@ -2899,6 +2899,7 @@ class Code: public HeapObject {
   DISALLOW_IMPLICIT_CONSTRUCTORS(Code);
 };
 
+typedef void (*Scavenger)(Map* map, HeapObject** slot, HeapObject* object);
 
 // All heap objects have a Map that describes their structure.
 //  A Map contains information about:
@@ -3100,6 +3101,13 @@ class Map: public HeapObject {
   void MapVerify();
 #endif
 
+  inline Scavenger scavenger();
+  inline void set_scavenger(Scavenger callback);
+
+  inline void Scavenge(HeapObject** slot, HeapObject* obj) {
+    scavenger()(this, slot, obj);
+  }
+
   static const int kMaxPreAllocatedPropertyFields = 255;
 
   // Layout description.
@@ -3110,7 +3118,8 @@ class Map: public HeapObject {
   static const int kInstanceDescriptorsOffset =
       kConstructorOffset + kPointerSize;
   static const int kCodeCacheOffset = kInstanceDescriptorsOffset + kPointerSize;
-  static const int kPadStart = kCodeCacheOffset + kPointerSize;
+  static const int kScavengerCallbackOffset = kCodeCacheOffset + kPointerSize;
+  static const int kPadStart = kScavengerCallbackOffset + kPointerSize;
   static const int kSize = MAP_POINTER_ALIGN(kPadStart);
 
   // Layout of pointer fields. Heap iteration code relies on them

src/serialize.cc

@@ -673,6 +673,14 @@ void Deserializer::ReadObject(int space_number,
     LOG(SnapshotPositionEvent(address, source_->position()));
   }
   ReadChunk(current, limit, space_number, address);
+
+  if (space == Heap::map_space()) {
+    ASSERT(size == Map::kSize);
+    HeapObject* obj = HeapObject::FromAddress(address);
+    Map* map = reinterpret_cast<Map*>(obj);
+    map->set_scavenger(Heap::GetScavenger(map->instance_type(),
+                                          map->instance_size()));
+  }
 }