Make InToSpace/InFromSpace use the page header.

src/spaces.cc

Index: src/spaces.cc
diff --git a/src/spaces.cc b/src/spaces.cc
index 157458d4680d2064274f730026d76c5b9e269103..ed414fb38bb4fad5db499fee667e6e3cbb514598 100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -391,14 +391,20 @@ void Page::InitializeAsAnchor(PagedSpace* owner) {
 }
 
 
-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->SetFlagTo(MemoryChunk::IN_TO_SPACE, in_to_space);
   heap->incremental_marking()->SetNewSpacePageFlags(chunk);
   return static_cast<NewSpacePage*>(chunk);
 }
@@ -932,9 +938,18 @@ void NewSpace::Flip() {
   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();
+  // GC related flags.
+  intptr_t mask =
+    (1 << MemoryChunk::WAS_SWEPT_CONSERVATIVELY) |
+    (1 << MemoryChunk::CONTAINS_ONLY_DATA) |
+    (1 << MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING) |
+    (1 << MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING) |
+    (1 << MemoryChunk::SCAN_ON_SCAVENGE);

[Lasse Reichstein, 2011/05/24 10:54:57]

Vyacheslav, is this the correct flags to move? Or more or less?

[Vyacheslav Egorov (Chromium), 2011/05/24 10:58:47]

I think POINTERS_FROM_HERE_ARE_INTERESTING  POINTERS_TO_HERE_ARE_INTERESTING,
SCAN_ON_SCAVENGE should be enough. Other flags should not be set on a new space
page.

I recommend moving this mask to the spaces.h where flags enum is defined so
we'll keep it up to date when we add more flags.

[Lasse Reichstein, 2011/05/24 12:29:03]

Reduced and added as constant in NewSpacePage.

+  to_space_.Flip(flags, mask);
+
+  from_space_.Flip(0, 0);
 }
 
 
@@ -1035,7 +1050,8 @@ bool SemiSpace::Commit() {
   committed_ = true;
   // TODO(gc): When more than one page is present, initialize and
   // chain them all.
-  current_page_ = NewSpacePage::Initialize(heap(), start_);
+  SemiSpaceId semispace = is_to_space_ ? kToSpace : kFromSpace;
+  current_page_ = NewSpacePage::Initialize(heap(), start_, semispace);
   return true;
 }
 
@@ -1134,6 +1150,22 @@ bool SemiSpace::ShrinkTo(int new_capacity) {
 }
 
 
+void SemiSpace::Flip(intptr_t flags, intptr_t mask) {
+  is_to_space_ = !is_to_space_;

[Erik Corry, 2011/05/24 11:25:50]

This can be written in terms of GetFlag and SetFlag for more clarity.

[Lasse Reichstein, 2011/05/24 12:29:03]

No, it works on the "flags" argument, not the "flags_" field.

+  intptr_t in_to_space_mask = (1 << MemoryChunk::IN_TO_SPACE);
+  if (is_to_space_) {
+    flags |= in_to_space_mask;
+  } else {
+    flags &= ~in_to_space_mask;
+  }
+  mask |= in_to_space_mask;
+  NewSpacePage* page = NewSpacePage::FromAddress(start_);
+  while (page != NULL) {
+    page->SetFlags(flags, mask);
+    page = page->next_page();
+  }
+}
+
 #ifdef DEBUG
 void SemiSpace::Print() { }