Made iteration of global handles more efficient on scavenges.

Review URL: http://codereview.chromium.org/355041


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3230 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/global-handles.cc

@@ -390,8 +390,8 @@ void GlobalHandles::PostGarbageCollectionProcessing() {
 }
 
 
-void GlobalHandles::IterateRoots(ObjectVisitor* v) {
-  // Traversal of global handles marked as NORMAL or NEAR_DEATH.
+void GlobalHandles::IterateStrongRoots(ObjectVisitor* v) {
+  // Traversal of global handles marked as NORMAL.
   for (Node* current = head_; current != NULL; current = current->next()) {
     if (current->state_ == Node::NORMAL) {
       v->VisitPointer(&current->object_);
@@ -400,6 +400,15 @@ void GlobalHandles::IterateRoots(ObjectVisitor* v) {
 }
 
 
+void GlobalHandles::IterateAllRoots(ObjectVisitor* v) {
+  for (Node* current = head_; current != NULL; current = current->next()) {
+    if (current->state_ != Node::DESTROYED) {
+      v->VisitPointer(&current->object_);
+    }
+  }
+}
+
+
 void GlobalHandles::TearDown() {
   // Reset all the lists.
   set_head(NULL);

src/global-handles.h

@@ -95,8 +95,11 @@ class GlobalHandles : public AllStatic {
   // Process pending weak handles.
   static void PostGarbageCollectionProcessing();
 
+  // Iterates over all strong handles.
+  static void IterateStrongRoots(ObjectVisitor* v);
+
   // Iterates over all handles.
-  static void IterateRoots(ObjectVisitor* v);
+  static void IterateAllRoots(ObjectVisitor* v);
 
   // Iterates over all weak roots in heap.
   static void IterateWeakRoots(ObjectVisitor* v);

src/globals.h

@@ -295,6 +295,8 @@ enum GarbageCollector { SCAVENGER, MARK_COMPACTOR };
 
 enum Executability { NOT_EXECUTABLE, EXECUTABLE };
 
+enum VisitMode { VISIT_ALL, VISIT_ONLY_STRONG };
+
 
 // A CodeDesc describes a buffer holding instructions and relocation
 // information. The instructions start at the beginning of the buffer

src/heap-profiler.cc

@@ -536,7 +536,7 @@ RetainerHeapProfile::RetainerHeapProfile()
     : zscope_(DELETE_ON_EXIT) {
   JSObjectsCluster roots(JSObjectsCluster::ROOTS);
   ReferencesExtractor extractor(roots, this);
-  Heap::IterateRoots(&extractor);
+  Heap::IterateRoots(&extractor, VISIT_ONLY_STRONG);
 }
 
 

src/heap.cc

@@ -733,10 +733,7 @@ void Heap::Scavenge() {
 
   ScavengeVisitor scavenge_visitor;
   // Copy roots.
-  IterateRoots(&scavenge_visitor);
-
-  // Copy objects reachable from weak pointers.
-  GlobalHandles::IterateWeakRoots(&scavenge_visitor);
+  IterateRoots(&scavenge_visitor, VISIT_ALL);
 
   // Copy objects reachable from the old generation.  By definition,
   // there are no intergenerational pointers in code or data spaces.
@@ -3117,7 +3114,7 @@ void Heap::Verify() {
   ASSERT(HasBeenSetup());
 
   VerifyPointersVisitor visitor;
-  IterateRoots(&visitor);
+  IterateRoots(&visitor, VISIT_ONLY_STRONG);
 
   new_space_.Verify();
 
@@ -3244,14 +3241,14 @@ void Heap::IterateRSet(PagedSpace* space, ObjectSlotCallback copy_object_func) {
 }
 
 
-void Heap::IterateRoots(ObjectVisitor* v) {
-  IterateStrongRoots(v);
+void Heap::IterateRoots(ObjectVisitor* v, VisitMode mode) {
+  IterateStrongRoots(v, mode);
   v->VisitPointer(reinterpret_cast<Object**>(&roots_[kSymbolTableRootIndex]));
   v->Synchronize("symbol_table");
 }
 
 
-void Heap::IterateStrongRoots(ObjectVisitor* v) {
+void Heap::IterateStrongRoots(ObjectVisitor* v, VisitMode mode) {
   v->VisitPointers(&roots_[0], &roots_[kStrongRootListLength]);
   v->Synchronize("strong_root_list");
 
@@ -3284,7 +3281,11 @@ void Heap::IterateStrongRoots(ObjectVisitor* v) {
   v->Synchronize("builtins");
 
   // Iterate over global handles.
-  GlobalHandles::IterateRoots(v);
+  if (mode == VISIT_ONLY_STRONG) {
+    GlobalHandles::IterateStrongRoots(v);
+  } else {
+    GlobalHandles::IterateAllRoots(v);
+  }
   v->Synchronize("globalhandles");
 
   // Iterate over pointers being held by inactive threads.
@@ -3893,7 +3894,7 @@ void Heap::TracePathToObject() {
   search_for_any_global = false;
 
   MarkRootVisitor root_visitor;
-  IterateRoots(&root_visitor);
+  IterateRoots(&root_visitor, VISIT_ONLY_STRONG);
 }
 
 
@@ -3905,7 +3906,7 @@ void Heap::TracePathToGlobal() {
   search_for_any_global = true;
 
   MarkRootVisitor root_visitor;
-  IterateRoots(&root_visitor);
+  IterateRoots(&root_visitor, VISIT_ONLY_STRONG);
 }
 #endif
 

src/heap.h

@@ -730,9 +730,9 @@ class Heap : public AllStatic {
   static String* hidden_symbol() { return hidden_symbol_; }
 
   // Iterates over all roots in the heap.
-  static void IterateRoots(ObjectVisitor* v);
+  static void IterateRoots(ObjectVisitor* v, VisitMode mode);
   // Iterates over all strong roots in the heap.
-  static void IterateStrongRoots(ObjectVisitor* v);
+  static void IterateStrongRoots(ObjectVisitor* v, VisitMode mode);
 
   // Iterates remembered set of an old space.
   static void IterateRSet(PagedSpace* space, ObjectSlotCallback callback);

src/mark-compact.cc

@@ -593,7 +593,7 @@ void MarkCompactCollector::MarkSymbolTable() {
 void MarkCompactCollector::MarkRoots(RootMarkingVisitor* visitor) {
   // Mark the heap roots including global variables, stack variables,
   // etc., and all objects reachable from them.
-  Heap::IterateStrongRoots(visitor);
+  Heap::IterateStrongRoots(visitor, VISIT_ONLY_STRONG);
 
   // Handle the symbol table specially.
   MarkSymbolTable();
@@ -1455,7 +1455,7 @@ void MarkCompactCollector::UpdatePointers() {
   state_ = UPDATE_POINTERS;
 #endif
   UpdatingVisitor updating_visitor;
-  Heap::IterateRoots(&updating_visitor);
+  Heap::IterateRoots(&updating_visitor, VISIT_ONLY_STRONG);
   GlobalHandles::IterateWeakRoots(&updating_visitor);
 
   int live_maps = IterateLiveObjects(Heap::map_space(),

src/serialize.cc

@@ -1101,7 +1101,7 @@ void Serializer::Serialize() {
   InitializeAllocators();
   reference_encoder_ = new ExternalReferenceEncoder();
   PutHeader();
-  Heap::IterateRoots(this);
+  Heap::IterateRoots(this, VISIT_ONLY_STRONG);
   PutLog();
   PutContextStack();
   Disable();
@@ -1204,7 +1204,7 @@ void Serializer::PutHeader() {
   writer_->PutC('G');
   writer_->PutC('[');
   GlobalHandlesRetriever ghr(&global_handles_);
-  GlobalHandles::IterateRoots(&ghr);
+  GlobalHandles::IterateStrongRoots(&ghr);
   for (int i = 0; i < global_handles_.length(); i++) {
     writer_->PutC('N');
   }
@@ -1441,7 +1441,7 @@ class GlobalHandleDestroyer : public ObjectVisitor {
 void Deserializer::Deserialize() {
   // No global handles.
   NoGlobalHandlesChecker checker;
-  GlobalHandles::IterateRoots(&checker);
+  GlobalHandles::IterateStrongRoots(&checker);
   // No active threads.
   ASSERT_EQ(NULL, ThreadState::FirstInUse());
   // No active handles.
@@ -1450,12 +1450,12 @@ void Deserializer::Deserialize() {
   // By setting linear allocation only, we forbid the use of free list
   // allocation which is not predicted by SimulatedAddress.
   GetHeader();
-  Heap::IterateRoots(this);
+  Heap::IterateRoots(this, VISIT_ONLY_STRONG);
   GetContextStack();
   // Any global handles that have been set up by deserialization are leaked
   // since noone is keeping track of them.  So we discard them now.
   GlobalHandleDestroyer destroyer;
-  GlobalHandles::IterateRoots(&destroyer);
+  GlobalHandles::IterateStrongRoots(&destroyer);
 }
 
 
@@ -1858,7 +1858,7 @@ void Deserializer2::Deserialize() {
   ASSERT(HandleScopeImplementer::instance()->blocks()->is_empty());
   ASSERT(external_reference_decoder_ == NULL);
   external_reference_decoder_ = new ExternalReferenceDecoder();
-  Heap::IterateRoots(this);
+  Heap::IterateRoots(this, VISIT_ONLY_STRONG);
   ASSERT(source_->AtEOF());
   delete external_reference_decoder_;
   external_reference_decoder_ = NULL;
@@ -2129,7 +2129,7 @@ void Serializer2::Serialize() {
   CHECK_EQ(0, GlobalHandles::NumberOfWeakHandles());
   ASSERT(external_reference_encoder_ == NULL);
   external_reference_encoder_ = new ExternalReferenceEncoder();
-  Heap::IterateRoots(this);
+  Heap::IterateRoots(this, VISIT_ONLY_STRONG);
   delete external_reference_encoder_;
   external_reference_encoder_ = NULL;
 }