Make InToSpace/InFromSpace use the page header.

src/spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 373 matching lines @@
 }
 
 
 void Page::InitializeAsAnchor(PagedSpace* owner) {
   set_owner(owner);
   set_prev_page(this);
   set_next_page(this);
 }
 
 
-NewSpacePage* NewSpacePage::Initialize(Heap* heap, Address start) {
+NewSpacePage* NewSpacePage::Initialize(Heap* heap,
+                                       Address start,
+                                       SemiSpaceId semispace_id) {
   MemoryChunk* chunk = MemoryChunk::Initialize(heap,
                                                start,
                                                Page::kPageSize,
                                                NOT_EXECUTABLE,
                                                heap->new_space());
+  chunk->set_next_chunk(NULL);
+  chunk->set_prev_chunk(NULL);
   chunk->initialize_scan_on_scavenge(true);
-  chunk->SetFlag(MemoryChunk::IN_NEW_SPACE);
+  bool in_to_space = (semispace_id != kFromSpace);
+  chunk->SetFlag(in_to_space ? MemoryChunk::IN_TO_SPACE
+                             : MemoryChunk::IN_FROM_SPACE);
+  ASSERT(!chunk->IsFlagSet(in_to_space ? MemoryChunk::IN_FROM_SPACE
+                                       : MemoryChunk::IN_TO_SPACE));
   heap->incremental_marking()->SetNewSpacePageFlags(chunk);
   return static_cast<NewSpacePage*>(chunk);
 }
 
 
 MemoryChunk* MemoryChunk::Initialize(Heap* heap,
                                      Address base,
                                      size_t size,
                                      Executability executable,
                                      Space* owner) {
@@ skipping 513 matching lines @@
 }
 
 #endif
 
 
 void NewSpace::Flip() {
   SemiSpace tmp = from_space_;
   from_space_ = to_space_;
   to_space_ = tmp;
 
-  NewSpacePage* old_active_page = from_space_.current_page();
-  NewSpacePage* new_active_page = to_space_.current_page();
-  new_active_page->CopyFlagsFrom(old_active_page);
+  // Copy GC flags from old active space (from-space) to new (to-space).
+  intptr_t flags = from_space_.current_page()->GetFlags();
+  to_space_.Flip(flags, NewSpacePage::kCopyOnFlipFlagsMask);
+
+  from_space_.Flip(0, 0);
 }
 
 
 void NewSpace::Grow() {
   ASSERT(Capacity() < MaximumCapacity());
   if (to_space_.Grow()) {
     // Only grow from space if we managed to grow to space.
     if (!from_space_.Grow()) {
       // If we managed to grow to space but couldn't grow from space,
       // attempt to shrink to space.
@@ skipping 80 matching lines @@
 
 bool SemiSpace::Commit() {
   ASSERT(!is_committed());
   if (!heap()->isolate()->memory_allocator()->CommitBlock(
       start_, capacity_, executable())) {
     return false;
   }
   committed_ = true;
   // TODO(gc): When more than one page is present, initialize and
   // chain them all.
-  current_page_ = NewSpacePage::Initialize(heap(), start_);
+  current_page_ = NewSpacePage::Initialize(heap(), start_, id_);
   return true;
 }
 
 
 bool SemiSpace::Uncommit() {
   ASSERT(is_committed());
   if (!heap()->isolate()->memory_allocator()->UncommitBlock(
       start_, capacity_)) {
     return false;
   }
@@ skipping 78 matching lines @@
   ASSERT(IsAligned(delta, OS::AllocateAlignment()));
   if (!heap()->isolate()->memory_allocator()->UncommitBlock(
       high() - delta, delta)) {
     return false;
   }
   capacity_ = new_capacity;
   return true;
 }
 
 
+void SemiSpace::Flip(intptr_t flags, intptr_t mask) {
+  bool becomes_to_space = (id_ == kFromSpace);
+  id_ = becomes_to_space ? kToSpace : kFromSpace;

[Erik Corry, 2011/05/24 12:38:36]

This can all be rewritten in terms of SetFlag and ClearFlag on each page.

+  intptr_t semi_space_mask =
+    (1 << MemoryChunk::IN_FROM_SPACE) | (1 << MemoryChunk::IN_TO_SPACE);
+  flags &= ~semi_space_mask;
+  if (becomes_to_space) {
+    flags |= 1 << MemoryChunk::IN_TO_SPACE;
+  } else {
+    flags |= 1 << MemoryChunk::IN_FROM_SPACE;
+  }
+  mask |= semi_space_mask;
+  NewSpacePage* page = NewSpacePage::FromAddress(start_);
+  while (page != NULL) {
+    page->SetFlags(flags, mask);
+    page = page->next_page();
+  }
+}
+
 #ifdef DEBUG
 void SemiSpace::Print() { }
 
 
 void SemiSpace::Verify() { }
 #endif
 
 
 // -----------------------------------------------------------------------------
 // SemiSpaceIterator implementation.
@@ skipping 1118 matching lines @@
   for (HeapObject* obj = obj_it.Next(); obj != NULL; obj = obj_it.Next()) {
     if (obj->IsCode()) {
       Code* code = Code::cast(obj);
       isolate->code_kind_statistics()[code->kind()] += code->Size();
     }
   }
 }
 #endif  // DEBUG
 
 } }  // namespace v8::internal